WorldWideScience

Sample records for valves problems tests

  1. 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.

  2. Risks for Heart Valve Problems

    Science.gov (United States)

    ... Thromboembolism Aortic Aneurysm More Risks for Heart Valve Problems Updated:Jan 18,2017 Who is at risk ... content was last reviewed May 2016. Heart Valve Problems and Disease • Home • About Heart Valves • Heart Valve ...

  3. Problem: Mitral Valve Regurgitation

    Science.gov (United States)

    ... State SELECT YOUR LANGUAGE Español (Spanish) 简体中文 (Traditional Chinese) 繁体中文 (Simplified Chinese) Tiếng Việt (Vietnamese) Healthy Living for Heart.org ... each time the left ventricle contracts. Watch an animation of mitral valve regurgitation A leaking mitral valve ...

  4. Problem: Heart Valve Regurgitation

    Science.gov (United States)

    ... State SELECT YOUR LANGUAGE Español (Spanish) 简体中文 (Traditional Chinese) 繁体中文 (Simplified Chinese) Tiếng Việt (Vietnamese) Healthy Living for Heart.org ... should be completely closed For example: Watch an animation of mitral valve regurgitation A leaking mitral valve ...

  5. Potential problems will drillstring safety valves

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-06-01

    In the paper titled ``New generation drill string safety valves,`` presented at the IADC Well Control Conference for Europe, Aberdeen, May 22--24, 1996, documented limitations of presently available drillstring safety valves commonly used as kelly valves and stabbing valves were presented, and industry efforts to develop solutions to these problems were described. Authors of the paper are B.A. Tarr and R.A. Sukup (Mobil E and P Technology Center, Dallas), Dr. R. Luy (ITE, Clausthal, Germany), G. Rabby (Hi-Kalibre, Edmonton, Alberta) and J. Mertsch (ITAG, Celle, Germany). In 1995, the Task Group developed a draft of a new spec, and a DSSV testing program was initiated as a joint industry project, with the Gas Research Institute (GRI) as the major sponsor. Two manufacturers, Hi-Kalibre and ITAG, agreed to build new valves for the testing program. Hi-Kalibre, Edmonton, Alberta, supplied an already-commercial twin floating ball valve for November 1995 testing. This product is being used by Tesco in its portable top drive system. ITAG of Germany supplied a radically improved DSSV design, which was tested in December, and was to be retested in May following modifications.

  6. 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)

  7. Large scale steam valve test: Performance testing of large butterfly valves and full scale high flowrate steam testing

    Energy Technology Data Exchange (ETDEWEB)

    Meadows, J.B.; Robbins, G.E.; Roselius, D.G. [and others

    1995-05-01

    This report presents the results of the design testing of large (36-inch diameter) butterfly valves under high flow conditions. The two butterfly valves were pneumatically operated air-open, air-shut valves (termed valves 1 and 2). These butterfly valves were redesigned to improve their ability to function under high flow conditions. Concern was raised regarding the ability of the butterfly valves to function as required with high flow-induced torque imposed on the valve discs during high steam flow conditions. High flow testing was required to address the flow-induced torque concerns. The valve testing was done using a heavily instrumented piping system. This test program was called the Large Scale Steam Valve Test (LSSVT). The LSSVT program demonstrated that the redesigned valves operated satisfactorily under high flow conditions.

  8. Europa Propulsion Valve Seat Material Testing

    Science.gov (United States)

    Addona, Brad M.

    2017-01-01

    The Europa mission and spacecraft design presented unique challenges for selection of valve seat materials that met the fluid compatibility requirements, and combined fluid compatibility and high radiation exposure level requirements. The Europa spacecraft pressurization system valves will be exposed to fully saturated propellant vapor for the duration of the mission. The effects of Nitrogen Tetroxide (NTO) and Monomethylhydrazine (MMH) propellant vapors on heritage valve seat materials, such as Vespel SP-1 and Polychlorotrifluoroethylene (PCTFE), were evaluated to determine if an alternate material is required. In liquid system applications, Teflon is the only available compatible valve seat material. Radiation exposure data for Teflon in an air or vacuum environment has been previously documented. Radiation exposure data for Teflon in an oxidizer environment such as NTO, was not available, and it was unknown whether the effects would be similar to those on air-exposed samples. Material testing was conducted by Marshall Space Flight Center (MSFC) and White Sands Test Facility (WSTF) to determine the effects of propellant vapor on heritage seat materials for pressurization valve applications, and the effects of combined radiation and NTO propellant exposure on Teflon. The results indicated that changes in heritage pressurization valve seat materials' properties rendered them unsuitable for the Europa application. The combined radiation and NTO exposure testing of Teflon produced results equivalent to combined radiation and air exposure results.

  9. Experimental apparatus to test air trap valves

    Science.gov (United States)

    Lemos De Lucca, Y. de F.; de Aquino, G. A.; Filho, J. G. D.

    2010-08-01

    It is known that the presence of trapped air within water distribution pipes can lead to irregular operation or even damage to the distribution systems and their components. The presence of trapped air may occur while the pipes are being filled with water, or while the pumping systems are in operation. The formation of large air pockets can produce the water hammer phenomenon, the instability and the loss of pressure in the water distribution networks. As a result, it can overload the pumps, increase the consumption of electricity, and damage the pumping system. In order to avoid its formation, all of the trapped air should be removed through "air trap valves". In Brazil, manufacturers frequently have unreliable sizing charts, which cause malfunctioning of the "air trap valves". The result of these malfunctions causes accidents of substantial damage. The construction of a test facility will provide a foundation of technical information that will be used to help make decisions when designing a system of pipelines where "air trap valves" are used. To achieve this, all of the valve characteristics (geometric, mechanic, hydraulic and dynamic) should be determined. This paper aims to describe and analyze the experimental apparatus and test procedure to be used to test "air trap valves". The experimental apparatus and test facility will be located at the University of Campinas, Brazil at the College of Civil Engineering, Architecture, and Urbanism in the Hydraulics and Fluid Mechanics laboratory. The experimental apparatus will be comprised of various components (pumps, steel pipes, butterfly valves to control the discharge, flow meter and reservoirs) and instrumentation (pressure transducers, anemometer and proximity sensor). It should be emphasized that all theoretical and experimental procedures should be defined while taking into consideration flow parameters and fluid properties that influence the tests.

  10. Experimental apparatus to test air trap valves

    Energy Technology Data Exchange (ETDEWEB)

    Lemos De Lucca, Y de F [CTH-DAEE-USP/FAAP/UNICAMP (Brazil); Aquino, G A de [SABESP/UNICAMP (Brazil); Filho, J G D, E-mail: yvone.lucca@gmail.co [Water Resources Department, University of Campinas-UNICAMP, Av. Albert Einstein, 951, Cidade Universitaria-Barao Geraldo-Campinas, S.P., 13083-852 (Brazil)

    2010-08-15

    It is known that the presence of trapped air within water distribution pipes can lead to irregular operation or even damage to the distribution systems and their components. The presence of trapped air may occur while the pipes are being filled with water, or while the pumping systems are in operation. The formation of large air pockets can produce the water hammer phenomenon, the instability and the loss of pressure in the water distribution networks. As a result, it can overload the pumps, increase the consumption of electricity, and damage the pumping system. In order to avoid its formation, all of the trapped air should be removed through 'air trap valves'. In Brazil, manufacturers frequently have unreliable sizing charts, which cause malfunctioning of the 'air trap valves'. The result of these malfunctions causes accidents of substantial damage. The construction of a test facility will provide a foundation of technical information that will be used to help make decisions when designing a system of pipelines where 'air trap valves' are used. To achieve this, all of the valve characteristics (geometric, mechanic, hydraulic and dynamic) should be determined. This paper aims to describe and analyze the experimental apparatus and test procedure to be used to test 'air trap valves'. The experimental apparatus and test facility will be located at the University of Campinas, Brazil at the College of Civil Engineering, Architecture, and Urbanism in the Hydraulics and Fluid Mechanics laboratory. The experimental apparatus will be comprised of various components (pumps, steel pipes, butterfly valves to control the discharge, flow meter and reservoirs) and instrumentation (pressure transducers, anemometer and proximity sensor). It should be emphasized that all theoretical and experimental procedures should be defined while taking into consideration flow parameters and fluid properties that influence the tests.

  11. AeroValve Experimental Test Data Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Noakes, Mark W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-09-01

    This report documents the collection of experimental test data and presents performance characteristics for the AeroValve brand prototype pneumatic bidirectional solenoid valves tested at the Oak Ridge National Laboratory (ORNL) in July/August 2014 as part of a validation of AeroValve energy efficiency claims. The test stand and control programs were provided by AeroValve. All raw data and processing are included in the report attachments.

  12. Reliability Evaluation of Concentric Butterfly Valve Using Statistical Hypothesis Test

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Mu Seong; Choi, Jong Sik; Choi, Byung Oh; Kim, Do Sik [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2015-12-15

    A butterfly valve is a type of flow-control device typically used to regulate a fluid flow. This paper presents an estimation of the shape parameter of the Weibull distribution, characteristic life, and B10 life for a concentric butterfly valve based on a statistical analysis of the reliability test data taken before and after the valve improvement. The difference in the shape and scale parameters between the existing and improved valves is reviewed using a statistical hypothesis test. The test results indicate that the shape parameter of the improved valve is similar to that of the existing valve, and that the scale parameter of the improved valve is found to have increased. These analysis results are particularly useful for a reliability qualification test and the determination of the service life cycles.

  13. Investigation of valve failure problems in LWR power plants

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-04-01

    An analysis of component failures from information in the computerized Nuclear Safety Information Center (NSIC) data bank shows that for both PWR and BWR plants the component category most responsible for approximately 19.3% of light water reactor (LWR) power plant shutdowns. This investigation by Burns and Roe, Inc. shows that the greatest cause of shutdowns in LWRs due to valve failures is leakage from valve stem packing. Both BWR plants and PWR plants have stem leakage problems (BWRs, 21% and PWRs, 34%).

  14. Simulant Development for Hanford Tank Farms Double Valve Isolation (DVI) Valves Testing

    Energy Technology Data Exchange (ETDEWEB)

    Wells, Beric E.

    2012-12-21

    Leakage testing of a representative sample of the safety-significant isolation valves for Double Valve Isolation (DVI) in an environment that simulates the abrasive characteristics of the Hanford Tank Farms Waste Transfer System during waste feed delivery to the Waste Treatment and Immobilization Plant (WTP) is to be conducted. The testing will consist of periodic leak performed on the DVI valves after prescribed numbers of valve cycles (open and close) in a simulated environment representative of the abrasive properties of the waste and the Waste Transfer System. The valve operations include exposure to cycling conditions that include gravity drain and flush operation following slurry transfer. The simulant test will establish the performance characteristics and verify compliance with the Documented Safety Analysis. Proper simulant development is essential to ensure that the critical process streams characteristics are represented, National Research Council report “Advice on the Department of Energy's Cleanup Technology Roadmap: Gaps and Bridges”

  15. The Development of the Code Safety Valve Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang Hyun; Kim, Young Ae; Park, Jong Woon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

    2007-07-01

    The Pressurizer Safety Valves (PSV) in Pressurized Water Reactors (PWRs) are required to provide the overpressure protection for the Reactor Coolant System (RCS) during the overpressure transients. According to the ASME OM code, all safety valves should be tested every 5 years with the acceptance tolerance of 1%. If one valve failed to meet this criterion, other two additional valves should be tested and if these valves don't meet the requirement, all valves should be tested. These frequent tests may make the valves decrepit and become a cause of leak. Therefore, increase of the acceptance tolerance is vital for the safe operation of the plant. In the United States, the acceptance tolerances are enlarged up to about 3% in most plants. This requires re-analysis of relevant accidents in FSAR. Also, the technical background data for the valve pop-up characteristics and the loop seal dynamics (if the plant has the loop seal in the upstream of PSV) are needed for the new safety analysis. Korea Hydro and Nuclear Power Company (KHNP) plans to build the PSV test facility for the purpose of providing the background data. This paper describes the preliminary design of the facility and studies on the system dynamics using GOTHIC-7.2a code to verify the pressure vessel capacities and to find the best operating condition.

  16. Aortic Calcification: An Early Sign of Heart Valve Problems?

    Science.gov (United States)

    ... the aortic valve — a condition called aortic valve stenosis. Aortic valve calcification may be an early sign ... have any other heart disease symptoms. Calcification and stenosis generally affects people older than age 65. When ...

  17. Fluid Dynamic Characterization of a Polymeric Heart Valve Prototype (Poli-Valve) tested under Continuous and Pulsatile Flow Conditions

    Science.gov (United States)

    De Gaetano, Francesco; Serrani, Marta; Bagnoli, Paola; Brubert, Jacob; Stasiak, Joanna; Moggridge, Geoff D.; Costantino, Maria Laura

    2016-01-01

    Introduction Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy, the latter display better fluid dynamic behaviour but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the haemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of two groups of newly developed supra-annular tri-leaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. Methods Two types of Poli-Valves made of SBC differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. An ad - hoc designed pulse duplicator allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the valve’s behaviour. Results Both types Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by ISO 5840 Standard. Results were compared with five mechanical heart valves (MHVs) and five tissue heart valves (THVs), currently available on the market. Conclusion Based on these results, polymeric heart valves based on styrenic block copolymers, as Poli-Valves are, can be considered as promising alternative for heart valve replacement in near future. PMID:26689146

  18. Test Rig for Valves of Digital Displacement Machines

    DEFF Research Database (Denmark)

    Nørgård, Christian; Christensen, Jeppe Haals; Bech, Michael Møller

    2017-01-01

    A test rig for the valves of digital displacement machines has been developed at Aalborg University. It is composed of a commercial radial piston machine, which has been modified to facilitate Digital Displacement operation for a single piston. Prototype valves have been optimized, designed...... and manufactured for testing and this paper presents examples of experimental results along with a thorough description of the test rig....

  19. Pressurizer Heater and Safety Valve Test for SPACE code

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Hyuk; Youn, Bum Soo; Jun, Hwang Yong; Kim, Se Yun; Ha, Sang Jun [KEPCO Research Institute, Daejeon (Korea, Republic of)

    2011-05-15

    The Korea nuclear industry has been developing a thermal-hydraulic analysis code for safety analysis of PWR(pressurized water reactor). The new code is named SPACE(Safety and Performance Analysis Code for Nuclear Power Plant). In this paper, the pressurizer heater model and safety valve for SPACE code is tested. The SPACE code input for pressurizer is developed and simulations are performed. Calculations were performed with and without heater and safety valve model and results are compared to confirm effectiveness of heater and safety valve

  20. Unsteady Analyses of Valve Systems in Rocket Engine Testing Environments

    Science.gov (United States)

    Shipman, Jeremy; Hosangadi, Ashvin; Ahuja, Vineet

    2004-01-01

    This paper discusses simulation technology used to support the testing of rocket propulsion systems by performing high fidelity analyses of feed system components. A generalized multi-element framework has been used to perform simulations of control valve systems. This framework provides the flexibility to resolve the structural and functional complexities typically associated with valve-based high pressure feed systems that are difficult to deal with using traditional Computational Fluid Dynamics (CFD) methods. In order to validate this framework for control valve systems, results are presented for simulations of a cryogenic control valve at various plug settings and compared to both experimental data and simulation results obtained at NASA Stennis Space Center. A detailed unsteady analysis has also been performed for a pressure regulator type control valve used to support rocket engine and component testing at Stennis Space Center. The transient simulation captures the onset of a modal instability that has been observed in the operation of the valve. A discussion of the flow physics responsible for the instability and a prediction of the dominant modes associated with the fluctuations is presented.

  1. LMFBR large valve development. Task II. IHTS isolation valve internals water test. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    DeWall, L.; Perschler, J.

    1975-01-01

    The purpose of this program was to perform proof-of-principle (POP) testing in water of a reduced bore rotating offset ball valve as required by AEC Contract No. AT(04-3)-1035. The water POP test article is shown on AMCO Drawing 16-E-4020, Sheets 1 through 4, dated 3-18-74. This report presents the water flow test results and the leakage results for one of the three seal designs.

  2. VERIFICATION TEST PROBLEMS

    Energy Technology Data Exchange (ETDEWEB)

    Moran, B

    2007-08-08

    We present analytic solutions to two test problems that can be used to check the hydrodynamic implementation in computer codes designed to calculate the propagation of shocks in spherically convergent geometry. Our analysis is restricted to fluid materials with constant bulk modulus. In the first problem we present the exact initial acceleration and pressure gradient at the outer surface of a sphere subjected to an exponentially decaying pressure of the form P(t) = P{sub 0}e{sup -at}. We show that finely-zoned hydro-code simulations are in good agreement with our analytic solution. In the second problem we discuss the implosions of incompressible spherical fluid shells and we present the radial pressure profile across the shell thickness. We also discuss a semi-analytic solution to the time-evolution of a nearly spherical shell with arbitrary but small initial 3-dimensional (3-D) perturbations on its inner and outer surfaces.

  3. Exercise Testing and Stress Imaging in Mitral Valve Disease.

    Science.gov (United States)

    Voilliot, Damien; Lancellotti, Patrizio

    2017-03-01

    Mitral valve disease represented by mitral stenosis and mitral regurgitation is the second most frequent valvulopathy. Mitral stenosis leads to an increased left atrial pressure whereas mitral regurgitation leads to an increased left atrial pressure associated with a volume overload. Secondary to an upstream transmission of this overpressure, both mitral stenosis and regurgitation lead to pulmonary hypertension and right heart failure. In addition, mitral regurgitation also leads to left ventricular dilatation and dysfunction with left heart failure. Depending on the anatomy of the valvular and subvalvular apparatus, valve repair (percutaneous mitral commissurotomy for mitral stenosis and valvuloplasty for mitral regurgitation) might be possible. If the anatomy is not favorable, valve replacement by mechanical or biological prosthesis is indicated. Most of the intervention indications are based on clinical symptoms and resting transthoracic echocardiography. Outcomes of patients operated based upon resting echo abnormalities might however not be optimal. Therefore early intervention might be beneficial based upon abnormal exercise testing, which has been demonstrated to more sensitive to identify high-risk patients. In this last decade, especially exercise echocardiography has been found to be a crucial tool in the management of patients with mitral valve disease.

  4. Design of Bioprosthetic Aortic Valves using biaxial test data.

    Science.gov (United States)

    Dabiri, Y; Paulson, K; Tyberg, J; Ronsky, J; Ali, I; Di Martino, E; Narine, K

    2015-01-01

    Bioprosthetic Aortic Valves (BAVs) do not have the serious limitations of mechanical aortic valves in terms of thrombosis. However, the lifetime of BAVs is too short, often requiring repeated surgeries. The lifetime of BAVs might be improved by using computer simulations of the structural behavior of the leaflets. The goal of this study was to develop a numerical model applicable to the optimization of durability of BAVs. The constitutive equations were derived using biaxial tensile tests. Using a Fung model, stress and strain data were computed from biaxial test data. SolidWorks was used to develop the geometry of the leaflets, and ABAQUS finite element software package was used for finite element calculations. Results showed the model is consistent with experimental observations. Reaction forces computed by the model corresponded with experimental measurements when the biaxial test was simulated. As well, the location of maximum stresses corresponded to the locations of frequent tearing of BAV leaflets. Results suggest that BAV design can be optimized with respect to durability.

  5. Solving economic dispatch problem with valve-point effects using swarm-based mean–variance mapping optimization (MVMOS

    Directory of Open Access Journals (Sweden)

    T.H. Khoa

    2015-12-01

    Full Text Available Mean–variance mapping optimization (MVMO is a new population-based metaheuristic technique which is successfully applied for different power system optimization problems. The special feature of MVMO is the mapping function applied for the mutation based on the mean and variance of n-best population. Recently, the modified version of MVMO has been developed to become more powerful, named as swarm-based mean–variance mapping optimization (MVMOS. This paper proposes MVMOS as a new approach for solving the economic dispatch (ED problem considering valve-point effects. To validate the performance of the proposed method, the MVMOS is tested on three systems including 3, 13, and 40 thermal generating units with valve-point effects and the obtained results from MVMOS are compared to those from other existing methods in the literature. Test results have indicated that the proposed MVMOS is more robust and produces better solution quality than many other methods. Therefore, the MVMOS is efficient for solving the ED with valve-point effects.

  6. Application of risk-based methods to inservice testing of check valves

    Energy Technology Data Exchange (ETDEWEB)

    Closky, N.B.; Balkey, K.R.; McAllister, W.J. [and others

    1996-12-01

    Research efforts have been underway in the American Society of Mechanical Engineers (ASME) and industry to define appropriate methods for the application of risk-based technology in the development of inservice testing (IST) programs for pumps and valves in nuclear steam supply systems. This paper discusses a pilot application of these methods to the inservice testing of check valves in the emergency core cooling system of Georgia Power`s Vogtle nuclear power station. The results of the probabilistic safety assessment (PSA) are used to divide the check valves into risk-significant and less-risk-significant groups. This information is reviewed by a plant expert panel along with the consideration of appropriate deterministic insights to finally categorize the check valves into more safety-significant and less safety-significant component groups. All of the more safety-significant check valves are further evaluated in detail using a failure modes and causes analysis (FMCA) to assist in defining effective IST strategies. A template has been designed to evaluate how effective current and emerging tests for check valves are in detecting failures or in finding significant conditions that are precursors to failure for the likely failure causes. This information is then used to design and evaluate appropriate IST strategies that consider both the test method and frequency. A few of the less safety-significant check valves are also evaluated using this process since differences exist in check valve design, function, and operating conditions. Appropriate test strategies are selected for each check valve that has been evaluated based on safety and cost considerations. Test strategies are inferred from this information for the other check valves based on similar check valve conditions. Sensitivity studies are performed using the PSA model to arrive at an overall IST program that maintains or enhances safety at the lowest achievable cost.

  7. Effects on fatigue life of gate valves due to higher torque switch settings during operability testing

    Energy Technology Data Exchange (ETDEWEB)

    Richins, W.D.; Snow, S.D.; Miller, G.K.; Russell, M.J.; Ware, A.G.

    1995-12-01

    Some motor operated valves now have higher torque switch settings due to regulatory requirements to ensure valve operability with appropriate margins at design basis conditions. Verifying operability with these settings imposes higher stem loads during periodic inservice testing. These higher test loads increase stresses in the various valve internal parts which may in turn increase the fatigue usage factors. This increased fatigue is judged to be a concern primarily in the valve disks, seats, yokes, stems, and stem nuts. Although the motor operators may also have significantly increased loading, they are being evaluated by the manufacturers and are beyond the scope of this study. Two gate valves representative of both relatively weak and strong valves commonly used in commercial nuclear applications were selected for fatigue analyses. Detailed dimensional and test data were available for both valves from previous studies at the Idaho National Engineering Laboratory. Finite element models were developed to estimate maximum stresses in the internal parts of the valves and to identity the critical areas within the valves where fatigue may be a concern. Loads were estimated using industry standard equations for calculating torque switch settings prior and subsequent to the testing requirements of USNRC Generic Letter 89--10. Test data were used to determine both; (1) the overshoot load between torque switch trip and final seating of the disk during valve closing and (2) the stem thrust required to open the valves. The ranges of peak stresses thus determined were then used to estimate the increase in the fatigue usage factors due to the higher stem thrust loads. The usages that would be accumulated by 100 base cycles plus one or eight test cycles per year over 40 and 60 years of operation were calculated.

  8. Test of a Novel Moving Magnet Actuated Seat Valve for Digital Displacement Fluid Power Machines

    DEFF Research Database (Denmark)

    Nørgård, Christian; Madsen, Esben Lundø; Christensen, Jeppe Haals

    2018-01-01

    electronicallycontrolled moving magnet actuated (MMA) annular seat valve is proposed, designed, built, and tested rigorously in the laboratory. The actuator is energized using one coil only, it has bidirectional force capability and it utilizes magnetic latching to keep it open instead of a spring. The annular seat valve...... has two metering edges; the static pressure drop is 0.11/0.31 bar at -142/108 l/min, respectively. The valve closing time is 4-6 ms depending on the flow rate. The MMA valve is tested experimentally in both standalone test rigs besides in situ tests in a fully operational digital displacement proto...... type machine. Measurements provided for pumping and motoring operation at 800 RPM/100 bar demonstrate that the proposed MMA valve topology is a promising candidate for energy-efficient digital displacement machines. Key characteristics include little power consumption, good switching performance...

  9. Our new tornado-compatible aortic valve prosthesis: notable results of hydrodynamic testing and experimental trials

    Directory of Open Access Journals (Sweden)

    Leo A. Bockeria

    2014-05-01

    Full Text Available Aims A shortcoming common to all existing designs of mechanical cardiac valve prostheses is an increased trombogenicity caused, among other factors, by the lack of hydrodynamic compatibility between the luminal part of the prosthesis and the patterned blood flow. The aim of the study is to design and test our new mechanical aortic valve prosthesis to exclude life-long anticoagulation treatment. Materials and methods Standard hydrodynamic tests of the new prosthetic valve have been carried out for comparing with the other existing valve designs. A new method for the heart valve prosthesis testing in a tornado-like flow has been developed. The valve function has been verified in a swine excluding the anticoagulation treatment during the period of time exceeding six months. Results The significant advantage of the new prosthesis in the standard hydrodynamic tests has been demonstrated. The tests in the tornado-like flow have shown that only this prosthesis allows maintaining the pattern, the head and flow rate characteristics of the tornado-like jet. Upon implanting the new prosthesis in the aortic position in a swine, the good performance of the valve without anticoagulation therapy has been confirmed in the course of more than six months. Conclusion Obtained has been the evidence of the merits of the new mechanical aortic valve owing to the due consideration of the hydrodynamic peculiarities of the aortic blood flow and the creation of the design providing the proper hydrodynamic compatibility.

  10. Proceedings of the symposium on inservice testing of pumps and valves

    Energy Technology Data Exchange (ETDEWEB)

    1990-10-01

    The 1990 Symposium on Inservice Testing of Pumps and Valves, jointly sponsored by the Board on Nuclear Codes and Standards of the American Society of Mechanical Engineers and by the Nuclear Regulatory Commission, provided a forum for the discussion of current programs and methods for inservice testing at nuclear power plants. The symposium also provided an opportunity to discuss the need to improve inservice testing in order to ensure the reliable performance of pumps and valves. The participation of industry representatives, regulators, and consultants resulted in the discussion of a broad spectrum of ideas and perspectives regarding the improvement of inservice testing of pumps and valves at nuclear power plants.

  11. ISOLOK VALVE ACCEPTANCE TESTING FOR DWPF SME SAMPLING PROCESS

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, T.; Hera, K.; Coleman, C.; Jones, M.; Wiedenman, B.

    2011-12-05

    Evaluation of the Defense Waste Processing Facility (DWPF) Chemical Process Cell (CPC) cycle time identified several opportunities to improve the CPC processing time. Of the opportunities, a focus area related to optimizing the equipment and efficiency of the sample turnaround time for DWPF Analytical Laboratory was identified. The Mechanical Systems & Custom Equipment Development (MS&CED) Section of the Savannah River National Laboratory (SRNL) evaluated the possibility of using an Isolok{reg_sign} sampling valve as an alternative to the Hydragard{reg_sign} valve for taking process samples. Previous viability testing was conducted with favorable results using the Isolok sampler and reported in SRNL-STI-2010-00749 (1). This task has the potential to improve operability, reduce maintenance time and decrease CPC cycle time. This report summarizes the results from acceptance testing which was requested in Task Technical Request (TTR) HLW-DWPF-TTR-2010-0036 (2) and which was conducted as outlined in Task Technical and Quality Assurance Plan (TTQAP) SRNL-RP-2011-00145 (3). The Isolok to be tested is the same model which was tested, qualified, and installed in the Sludge Receipt Adjustment Tank (SRAT) sample system. RW-0333P QA requirements apply to this task. This task was to qualify the Isolok sampler for use in the DWPF Slurry Mix Evaporator (SME) sampling process. The Hydragard, which is the current baseline sampling method, was used for comparison to the Isolok sampling data. The Isolok sampler is an air powered grab sampler used to 'pull' a sample volume from a process line. The operation of the sampler is shown in Figure 1. The image on the left shows the Isolok's spool extended into the process line and the image on the right shows the sampler retracted and then dispensing the liquid into the sampling container. To determine tank homogeneity, a Coliwasa sampler was used to grab samples at a high and low location within the mixing tank. Data from

  12. Mechanical testing of pericardium for manufacturing prosthetic heart valves.

    Science.gov (United States)

    Aguiari, Paola; Fiorese, Michele; Iop, Laura; Gerosa, Gino; Bagno, Andrea

    2016-01-01

    Mammalian pericardia are currently used for the production of percutaneous prosthetic heart valves. The characteristics of biological tissues largely influence the durability of prosthetic devices used in the percutaneous approach and in traditional surgery, too. This paper reviews methodologies employed to assess and compare mechanical properties of pericardial patches from different mammalian species in order to identify the biomaterials adequate for manufacturing prosthetic heart valves. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  13. Design and testing of magnetorheological valve with fast force response time and great dynamic force range

    Science.gov (United States)

    Kubík, M.; Macháček, O.; Strecker, Z.; Roupec, J.; Mazůrek, I.

    2017-04-01

    The paper deals with design, simulation and experimental testing of a magnetorheological (MR) valve with short response time. The short response time is achieved by a suitable design of an active zone in combination with use of a ferrite material for magnetic circuit. The magneto-static model and the simplified hydraulic model of the MR valve are examined and experimentally verified. The development the MR valve achieves an average response time 4.1 ms and the maximum dynamic force range of eight.

  14. Results of thermal test of metallic molybdenum disk target and fast-acting valve testing

    Energy Technology Data Exchange (ETDEWEB)

    Virgo, M. [Argonne National Lab. (ANL), Argonne, IL (United States); Chemerisov, S. [Argonne National Lab. (ANL), Argonne, IL (United States); Gromov, R. [Argonne National Lab. (ANL), Argonne, IL (United States); Jonah, C. [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, G. F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-12-01

    This report describes the irradiation conditions for thermal testing of helium-cooled metallic disk targets that was conducted on March 9, 2016, at the Argonne National Laboratory electron linac. The four disks in this irradiation were pressed and sintered by Oak Ridge National Laboratory from molybdenum metal powder. Two of those disks were instrumented with thermocouples. Also reported are results of testing a fast-acting-valve system, which was designed to protect the accelerator in case of a target-window failure.

  15. Development and testing of a passive check valve for cryogenic applications

    Science.gov (United States)

    Moore, B. D.; Maddocks, J. R.; Miller, F. K.

    2014-11-01

    Several cryogenic technologies use check valves, such as the Cold Cycle Dilution Refrigerator (CCDR) and the Hybrid Pulse-Tube/Reverse-Brayton Cryocooler. This paper details the development of a reed-style passive check valve with a PTFE seat for cryogenic applications. The experimental results of tests on the valve using helium gas at temperatures from 293 K down to 5.2 K, verify a scaling argument based on fundamental fluid dynamics that allows results from 78 K to be used in predicting valve performance at much lower temperatures. The scaling argument is then applied to a test conducted at the normal boiling point of Nitrogen to examine the results of improved fabrication methods.

  16. A novel synthetic test system for thyristor level in the converter valve of HVDC power transmission

    Directory of Open Access Journals (Sweden)

    Liu Longchen

    2016-01-01

    Full Text Available The converter valve is the core equipment in the HVDC power transmission system, a+-nd its performance has a direct effect on the reliability, stability and efficiency of the whole power system. As the basic unit of HVDC converter valve, the thyristor level needs to be test routinely in order to grasp the state of the converter valve equipment. Therefore, it is urgent to develop a novel synthetic test system for the thyristor level with thyristor control unit (TCU. However, currently there is no specific test scheme for the thyristor level of HVDC converter valve. In this paper, the synthetic test principle, content and methods for the thyristor level with TCU are presented based on the analysis of the thyristor reverse recovery characteristic and the IEC technology standard. And a transient high-voltage pulse is applied to the thyristor level during its reverse recovery period in order to test the characteristics of thyristor level. Then, the synthetic test system for the thyristor level is applied to the converter valve test of ±800 kV HVDC power transmission project, and the practical test result verifies the reasonability and validity of the proposed synthetic test system.

  17. 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.

  18. Medical Tests for Prostate Problems

    Science.gov (United States)

    ... male urinary tract What are some common prostate problems? The most common prostate problem in men younger ... than BPH. What are the symptoms of prostate problems? The symptoms of prostate problems may include urinary ...

  19. Acoustic-Modal Testing of the Ares I Launch Abort System Attitude Control Motor Valve

    Science.gov (United States)

    Davis, R. Benjamin; Fischbach, Sean R.

    2010-01-01

    The Attitude Control Motor (ACM) is being developed for use in the Launch Abort System (LAS) of NASA's Ares I launch vehicle. The ACM consists of a small solid rocket motor and eight actuated pintle valves that directionally allocate.thrust_- 1t.has-been- predicted-that significant unsteady. pressure.fluctuations.will.exist. inside the-valves during operation. The dominant frequencies of these oscillations correspond to the lowest several acoustic natural frequencies of the individual valves. An acoustic finite element model of the fluid volume inside the valve has been critical to the prediction of these frequencies and their associated mode shapes. This work describes an effort to experimentally validate the acoustic finite model of the valve with an acoustic modal test. The modal test involved instrumenting a flight-like valve with six microphones and then exciting the enclosed air with a loudspeaker. The loudspeaker was configured to deliver broadband noise at relatively high sound pressure levels. The aquired microphone signals were post-processed and compared to results generated from the acoustic finite element model. Initial comparisons between the test data and the model results revealed that additional model refinement was necessary. Specifically, the model was updated to implement a complex impedance boundary condition at the entrance to the valve supply tube. This boundary condition models the frequency-dependent impedance that an acoustic wave will encounter as it reaches the end of the supply tube. Upon invoking this boundary condition, significantly improved agreement between the test data and the model was realized.

  20. Preimplantation Flow Testing of Ahmed Glaucoma Valve and the Early Postoperative Clinical Outcome.

    Science.gov (United States)

    Jones, Emma; Alaghband, Pouya; Cheng, Jason; Beltran-Agullo, Laura; Sheng Lim, Kin

    2013-01-01

    The Ahmed glaucoma valve (AGV) implant is designed to prevent early postoperative hypotony. There is evidence of variation in hypotony rates in clinical trials which may be due to surgical technique variation, entry site leakage or valve defects from 'over priming'. We describe a simple preimplantation gravity driven test to assess valve function after priming that may reduce hypotony rates. Retrospective case note review. An in vivo flow test of AGVs, based on the gravity driven test was introduced prior to implantation. The onset and offset of flow through the valve was measured by altering the height of a bottle of balanced saline solution. We rejected the AGV, if there was fluid still flowing at 10 cm (7 mm Hg) or if there was no flow at 17 cm of water (12 mm Hg). The AGV implantation surgery was without mitomycin C, with a 25G needle entry tract, a corneal or scleral patch graft tube cover and without intracameral viscoelastic. Twenty Ahmed valves were implanted in 16 patients between July 2008 and October 2009. Test failure resulted in four AGV being rejected. The mean preoperative pressure was 29 mm Hg (range, 10-57 mm Hg) and the intraocular pressure (IOP) at 7 days postoperatively was 15 mm Hg (range, 3-52 mm Hg). Hypotony, defined as an IOP of less than 5 mm Hg on two consecutive assessments, was present in two eyes (10%). In vivo flow testing is an important safety check for the AGV. There are also other mechanisms after implantation that can cause an unexpected high or low IOP. How to cite this article: Jones E, Alaghband P, Cheng J, Beltran-Agullo L, Lim KS. Preimplantation Flow Testing of Ahmed Glaucoma Valve and the Early Postoperative Clinical Outcome. J Current Glau Prac 2013;7(1):1-5.

  1. Project W-314 specific test and evaluation plan 241-AN-B valve pit

    Energy Technology Data Exchange (ETDEWEB)

    Hays, W.H.

    1998-04-08

    The purpose of this Specific Test and Evaluation Plan (STEP) is to provide a detailed written plan for the systematic testing of modifications made to the 241-AN-B Valve Pit by the W-314 Project. The STEP develops the outline for test procedures that verify the system`s performance to the established Project design criteria. The STEP is a lower tier document based on the W-314 Test and Evaluation Plan (TEP).

  2. 42 CFR 84.1150 - Exhalation valve leakage test; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Exhalation valve leakage test; minimum requirements. 84.1150 Section 84.1150 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Dust...

  3. Six-minute walking test and long term prognosis in patients with asymptomatic aortic valve stenosis

    DEFF Research Database (Denmark)

    Sigvardsen, Per Ejlstrup; Larsen, Linnea Hornbech; Carstensen, Helle Gervig

    2017-01-01

    BACKGROUND: Management of asymptomatic patients with aortic valve stenosis is challenging due to the elusive relationship between symptomatic status and hemodynamic parameters in addition to the occurrence of cardiovascular death. The 6-minute walking test (6MWT) reflects overall hemodynamic func...

  4. Feasibility and testing of lighweight, energy efficient, additive manufactured pneumatic control valve

    Energy Technology Data Exchange (ETDEWEB)

    Love, Lonnie J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mell, Ellen [Aerovalve, LLC, St. Louis, Mo (United States)

    2015-02-01

    AeroValve s innovative pneumatic valve technology recycles compressed air through the valve body with each cycle of the valve, and was reported to reduce compressed air requirements by an average of 25% 30%.This technology collaboration project between ORNL and Aerovalve confirms the energy efficiency of valve performance. Measuring air consumption per work completed, the AeroValve was as much as 85% better than the commercial Festo valve.

  5. Collective neurodynamic optimization for economic emission dispatch problem considering valve point effect in microgrid.

    Science.gov (United States)

    Wang, Tiancai; He, Xing; Huang, Tingwen; Li, Chuandong; Zhang, Wei

    2017-09-01

    The economic emission dispatch (EED) problem aims to control generation cost and reduce the impact of waste gas on the environment. It has multiple constraints and nonconvex objectives. To solve it, the collective neurodynamic optimization (CNO) method, which combines heuristic approach and projection neural network (PNN), is attempted to optimize scheduling of an electrical microgrid with ten thermal generators and minimize the plus of generation and emission cost. As the objective function has non-derivative points considering valve point effect (VPE), differential inclusion approach is employed in the PNN model introduced to deal with them. Under certain conditions, the local optimality and convergence of the dynamic model for the optimization problem is analyzed. The capability of the algorithm is verified in a complicated situation, where transmission loss and prohibited operating zones are considered. In addition, the dynamic variation of load power at demand side is considered and the optimal scheduling of generators within 24 h is described. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Testing of one-inch UF{sub 6} cylinder valves under simulated fire conditions

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, P.G. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    Accurate computational models which predict the behavior of UF{sub 6} cylinders exposed to fires are required to validate existing firefighting and emergency response procedures. Since the cylinder valve is a factor in the containment provided by the UF{sub 6} cylinder, its behavior under fire conditions has been a necessary assumption in the development of such models. Consequently, test data is needed to substantiate these assumptions. Several studies cited in this document provide data related to the behavior of a 1-inch UF{sub 6} cylinder valve in fire situations. To acquire additional data, a series of tests were conducted at the Paducah Gaseous Diffusion Plant (PGDP) under a unique set of test conditions. This document describes this testing and the resulting data.

  7. An Improved Quantum-Behaved Particle Swarm Optimization Method for Economic Dispatch Problems with Multiple Fuel Options and Valve-Points Effects

    Directory of Open Access Journals (Sweden)

    Hong-Yun Zhang

    2012-09-01

    Full Text Available Quantum-behaved particle swarm optimization (QPSO is an efficient and powerful population-based optimization technique, which is inspired by the conventional particle swarm optimization (PSO and quantum mechanics theories. In this paper, an improved QPSO named SQPSO is proposed, which combines QPSO with a selective probability operator to solve the economic dispatch (ED problems with valve-point effects and multiple fuel options. To show the performance of the proposed SQPSO, it is tested on five standard benchmark functions and two ED benchmark problems, including a 40-unit ED problem with valve-point effects and a 10-unit ED problem with multiple fuel options. The results are compared with differential evolution (DE, particle swarm optimization (PSO and basic QPSO, as well as a number of other methods reported in the literature in terms of solution quality, convergence speed and robustness. The simulation results confirm that the proposed SQPSO is effective and reliable for both function optimization and ED problems.

  8. Design and test of a simple fast electromagnetic inductive gas valve for planar pulsed inductive plasma thruster

    Science.gov (United States)

    Guo, Dawei; Cheng, Mousen; Li, Xiaokang

    2017-10-01

    In support of our planar pulsed inductive plasma thruster research, a fast electromagnetic inductive valve for a gas propellant injection system has been built and tested. A new and important design feature is the use of a conical diaphragm as the action part, which greatly contributes to the virtue of simplicity for adopting the resultant force of the diaphragm deformation as the closing force. An optical transmission technique is adopted to measure the opening and closing characters of the valve while the gas throughput is determined by measuring the pressure change per pulse in a test chamber with a capacitance manometer. The experimental results revealed that the delay time before the valve reaction is less than 40 μs, and the valve pulse width is no longer than 160 μs full width at half maximum. The valve delivers 0-2.5 mg of argon gas per pulse varied by adjusting the drive voltage and gas pressure.

  9. Current Progress in Tissue Engineering of Heart Valves: Multiscale Problems, Multiscale Solutions

    Science.gov (United States)

    Cheung, Daniel Y; Duan, Bin; Butcher, Jonathan T.

    2016-01-01

    Introduction Heart valve disease is an increasingly prevalent and clinically serious condition. There are no clinically effective biological diagnostics or treatment strategies. The only recourse available is replacement with a prosthetic valve, but the inability of these devices to grow or respond biologically to their environments necessitates multiple resizing surgeries and life-long coagulation treatment, especially in children. Tissue engineering has a unique opportunity to impact heart valve disease by providing a living valve conduit, capable of growth and biological integration. Areas covered This review will cover current tissue engineering strategies in fabricating heart valves and their progress towards the clinic, including molded scaffolds using naturally-derived or synthetic polymers, decellularization, electrospinning, 3D bioprinting, hybrid techniques, and in vivo engineering. Expert opinion While much progress has been made to create functional living heart valves, a clinically viable product is not yet realized. The next leap in engineered living heart valves will require a deeper understanding of how the natural multi-scale structural and biological heterogeneity of the tissue ensures its efficient function. Related, improved fabrication strategies must be developed that can replicate this de novo complexity, which is likely instructive for appropriate cell differentiation and remodeling whether seeded with autologous stem cells in vitro or endogenously recruited cells. PMID:26027436

  10. Standardized Definitions for Code Verification Test Problems

    Energy Technology Data Exchange (ETDEWEB)

    Doebling, Scott William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-14

    This document contains standardized definitions for several commonly used code verification test problems. These definitions are intended to contain sufficient information to set up the test problem in a computational physics code. These definitions are intended to be used in conjunction with exact solutions to these problems generated using Exact- Pack, www.github.com/lanl/exactpack.

  11. When a Heart Murmur Signals Valve Disease

    Science.gov (United States)

    ... Order AHA Brochures Your Heart Valve Surgery Your Mitral Valve Prolapse Innocent Heart Murmurs If Your Child Has a Congenital Heart Defect See all of our brochures Valve Disease Resources Patient Guide: Understanding Your Heart Valve Problem | ...

  12. Tricuspid valve endocarditis following central venous cannulation: The increasing problem of catheter related infection

    Directory of Open Access Journals (Sweden)

    Suresh Babu Kale

    2013-01-01

    Full Text Available A central venous catheter (CVC is inserted for measurement of haemodynamic variables, delivery of nutritional supplements and drugs and access for haemodialysis and haemofiltration. Catheterization and maintenance are common practices and there is more to the technique than routine placement as evident when a procedure-related complication occurs. More than 15% of the patients who receive CVC placement have some complications and infectious endocarditis involving the tricuspid valve is a rare and serious complication with high morbidity and mortality. Overenthusiastic and deep insertion of the guide wire and forceful injection through the CVC may lead to injury of the tricuspid valve and predispose to bacterial deposition and endocarditis. We report a case of tricuspid valve endocarditis, probably secondary to injury of the anterior tricuspid leaflet by the guide wire or the CVC that required open heart surgery with vegetectomy and repair of the tricuspid valve.

  13. Testing of calibration and reconditioning of the pressurizer safety valves; Pruebas de tarado y reacondicionamiento de las valvulas de seguridad del presionador

    Energy Technology Data Exchange (ETDEWEB)

    Mediavilla, F.; Jardi, X.

    2014-07-01

    This paper presents All activities that are required in the proposal of Tecnatom as: transport of valves to the laboratory in special containers and preparation of the expedition of the radioactive packages testing of leakage of valves with nitrogen, leak and calibration with initial steam and final tests, overhaul of the valve including the process Jack and Lap and mounting and dismounting of valves in the plant. (Author)

  14. Solving infeasibility problems in computerized test assembly

    NARCIS (Netherlands)

    Timminga, E.

    Linear programming techniques have been used successfully in a variety of test assembly problems. It is, however, possible that no test can be found meeting all the constraints in the linear programming model. The problem of diagnosing and repairing infeasible linear programming models is discussed.

  15. Sequential testing problems for Poisson processes

    OpenAIRE

    Peskir, G; A.N. Shiryaev

    2000-01-01

    We present the explicit solution of the Bayesian problem of sequential testing of two simple hypotheses about the intensity of an observed Poisson process. The method of proof consists of reducing the initial problem to a free-boundary differential-difference Stephan problem and solving the latter by use of the principles of smooth and continuous fit. A rigorous proof of the optimality of the Wald’s sequential probability ratio test in the variational formulation of the prob...

  16. Test set for initial value problem solvers

    NARCIS (Netherlands)

    W.M. Lioen (Walter); J.J.B. de Swart (Jacques)

    1998-01-01

    textabstractThe CWI test set for IVP solvers presents a collection of Initial Value Problems to test solvers for implicit differential equations. This test set can both decrease the effort for the code developer to test his software in a reliable way, and cross the bridge between the application

  17. DEMOCRATIC PSO ALGORITHM FOR THE ECONOMIC DISPATCH PROBLEM WITH VALVE-POINT EFFECTS

    Directory of Open Access Journals (Sweden)

    SECUI D.C.

    2015-09-01

    Full Text Available This paper presents an optimization algorithm called Democratic Particle Swarm Optimization (DPSO, aiming to solve the economic dispatch problem. The DPSO algorithm is applied in the original version and also in a new version in which it is endowed with the chaotic Sine map (DPSO-Sine algorithm. The performance of DPSO and DPSOSine algorithms is tested on two systems having 13, and respectively 40 generating units. The results show that DPSO and DPSO-Sine have better performances than PSO algorithm and few other optimization techniques used to solve the economic dispatch problem.

  18. Thermal-hydraulic analysis for changing feedwater check valve leakage rate testing methodology

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, R.; Harrell, J.

    1996-12-01

    The current design and testing requirements for the feedwater check valves (FWCVs) at the Grand Gulf Nuclear Station are established from original licensing requirements that necessitate extremely restrictive air testing with tight allowable leakage limits. As a direct result of these requirements, the original high endurance hard seats in the FWCVs were modified with elastomeric seals to provide a sealing surface capable of meeting the stringent air leakage limits. However, due to the relatively short functional life of the elastomeric seals compared to the hard seats, the overall reliability of the sealing function actually decreased. This degraded performance was exhibited by frequent seal failures and subsequent valve repairs. The original requirements were based on limited analysis and the belief that all of the high energy feedwater vaporized during the LOCA blowdown. These phenomena would have resulted in completely voided feedwater lines and thus a steam environment within the feedwater leak pathway. To challenge these criteria, a comprehensive design basis accident analysis was developed using the RELAP5/MOD3.1 thermal-hydraulic code. Realistic assumptions were used to more accurately model the post-accident fluid conditions within the feedwater system. The results of this analysis demonstrated that no leak path exists through the feedwater lines during the reactor blowdown phase and that sufficient subcooled water remains in various portions of the feedwater piping to form liquid water loop seals that effectively isolate this leak path. These results provided the bases for changing the leak testing requirements of the FWCVs from air to water. The analysis results also established more accurate allowable leakage limits, determined the real effective margins associated with the FWCV safety functions, and led to design changes that improved the overall functional performance of the valves.

  19. Planar biaxial testing of heart valve cusp replacement biomaterials: Experiments, theory and material constants.

    Science.gov (United States)

    Labrosse, Michel R; Jafar, Reza; Ngu, Janet; Boodhwani, Munir

    2016-11-01

    Aortic valve (AV) repair has become an attractive option to correct aortic insufficiency. Yet, cusp reconstruction with various cusp replacement materials has been associated with greater long-term repair failures, and it is still unknown how such materials mechanically compare with native leaflets. We used planar biaxial testing to characterize six clinically relevant cusp replacement materials, along with native porcine AV leaflets, to ascertain which materials would be best suited for valve repair. We tested at least six samples of: 1) fresh autologous porcine pericardium (APP), 2) glutaraldehyde fixed porcine pericardium (GPP), 3) St Jude Medical pericardial patch (SJM), 4) CardioCel patch (CC), 5) PeriGuard (PG), 6) Supple PeriGuard (SPG) and 7) fresh porcine AV leaflets (PC). We introduced efficient displacement-controlled testing protocols and processing, as well as advanced convexity requirements on the strain energy functions used to describe the mechanical response of the materials under loading. The proposed experimental and data processing pipeline allowed for a robust in-plane characterization of all the materials tested, with constants determined for two Fung-like hyperelastic, anisotropic strain energy models. Overall, CC and SPG (respectively PG) patches ranked as the closest mechanical equivalents to young (respectively aged) AV leaflets. Because the native leaflets as well as CC, PG and SPG patches exhibit significant anisotropic behaviors, it is suggested that the fiber and cross-fiber directions of these replacement biomaterials be matched with those of the host AV leaflets. The long-term performance of cusp replacement materials would ideally be evaluated in large animal models for AV disease and cusp repair, and over several months or more. Given the unavailability and impracticality of such models, detailed information on stress-strain behavior, as studied herein, and investigations of durability and valve dynamics will be the best surrogates

  20. The Analysis of Loop Seal Purge Time for the KHNP Pressurizer Safety Valve Test Facility Using the GOTHIC Code

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Ae; Kim, Chang Hyun; Kweon, Gab Joo; Park, Jong Woon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

    2007-10-15

    The pressurizer safety valves (PSV) in Pressurized Water Reactors are required to provide the overpressure protection for the Reactor Coolant System (RCS) during the overpressure transients. Korea Hydro and Nuclear Power Company (KHNP) plans to build the PSV test facility for the purpose of providing the PSV pop-up characteristics and the loop seal dynamics for the new safety analysis. When the pressurizer safety valve is mounted in a loop seal configuration, the valve must initially pass the loop seal water prior to popping open on steam. The loop seal in the upstream of PSV prevents leakage of hydrogen gas or steam through the safety valve seat. This paper studies on the loop seal clearing dynamics using GOTHIC-7.2a code to verify the effects of loop seal purge time on the reactor coolant system overpressure.

  1. Parameterized study of the test cover problem

    DEFF Research Database (Denmark)

    Crowston, Robert; Gutin, Gregory; Jones, Mark

    2012-01-01

    In this paper we carry out a systematic study of a natural covering problem, used for identification across several areas, in the realm of parameterized complexity. In the Test Cover problem we are given a set [n] = {1,...,n} of items together with a collection, , of distinct subsets of these items...... called tests. We assume that is a test cover, i.e., for each pair of items there is a test in containing exactly one of these items. The objective is to find a minimum size subcollection of , which is still a test cover. The generic parameterized version of Test Cover is denoted by -Test Cover. Here, we...... are given and a positive integer parameter k as input and the objective is to decide whether there is a test cover of size at most . We study four parameterizations for Test Cover and obtain the following: (a) k-Test Cover, and (n - k)-Test Cover are fixed-parameter tractable (FPT), i.e., these problems can...

  2. Exercise stress testing enhances blood coagulation and impairs fibrinolysis in asymptomatic aortic valve stenosis.

    Science.gov (United States)

    Kolasa-Trela, Renata; Fil, Korneliusz; Wypasek, Ewa; Undas, Anetta

    2015-06-01

    Increased thrombin formation and fibrin deposition on the valves were observed in patients with severe aortic valve stenosis (AS). Exercise enhances blood coagulation and fibrinolysis in healthy subjects, but its haemostatic effects in AS are unknown. We sought to investigate how stress echocardiography alters blood coagulation and fibrinolysis in AS patients free of significant atherosclerotic vascular disease. We studied 32 consecutive asymptomatic moderate-to-severe AS patients and 32 age- and sex-matched controls. We measured peak thrombin generated using calibrated automated thrombogram, clot lysis time (CLT), and fibrinolytic markers at four time points, i.e. at rest, at peak exercise, and 1h and 24h after a symptom-limited exercise test. We observed that peak thrombin generated rose at peak exercise to 25% higher value in the patients than in controls (pfibrinolysis inhibitor (TAFI) activity (r=0.69, pfibrinolysis as compared to controls. Repeated episodes of exercise-induced prothrombotic state in AS might contribute to the progression of this disease. Copyright © 2014 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  3. Application of new designed butterfly type intermediate valve for nuclear steam turbine

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Kazuhiro; Kawamata, Susumu (Tokyo Electric Power Co., Inc. (Japan)); Fujita, Isao; Taketomo, Seiki

    1991-09-01

    To cope with a large capacity nuclear steam turbine, a butterfly type intermediate valve has been developed. Compared to the conventional valve, or globe valve, the butterfly valve has the following design features: (a) Higher thermal efficiency due to lower pressure loss, (b) Easier maintenance due to simplified construction, and (c) Lower station cost due to the smaller size of the valve assembly. An experiment with a scaled-down test valve was carried out using compressed air. Subsequently a full-scale valve was tested using steam under actual steam conditions. As a result, these tests gave us no problems. The first nuclear turbine (1100MW) equipped with a butterfly valve is operating satisfactorily with good performance as expected. (author).

  4. Problem-Solving Test: Tryptophan Operon Mutants

    Science.gov (United States)

    Szeberenyi, Jozsef

    2010-01-01

    This paper presents a problem-solving test that deals with the regulation of the "trp" operon of "Escherichia coli." Two mutants of this operon are described: in mutant A, the operator region of the operon carries a point mutation so that it is unable to carry out its function; mutant B expresses a "trp" repressor protein unable to bind…

  5. Developmental neurotoxicity test guidelines: problems and perspectives.

    Science.gov (United States)

    Tohyama, Chiharu

    2016-01-01

    Epidemiologic evidence has demonstrated associations between early life exposure to industrial chemicals and the occurrence of disease states, including cognitive and behavioral abnormalities, in children. The developing brain in the fetal and infantile periods is extremely vulnerable to chemicals because the blood-brain barrier is not completely formed during these periods. The Organisation for Economic Co-operation and Development (OECD) developmental neurotoxicity (DNT) test guideline, TG426, updated in 2007, comprises in vivo behavioral observational tests and other tests intended to assess DNT induced by exposure to industrial chemicals. These chemicals may enter the market without having been subjected to DNT testing, as DNT test data is not mandated by law at the time of chemical registration. In addition, proprietary rights have led to problems concerning the non-disclosure of industrial chemical toxicity test data, including DNT test data. To overcome the disadvantages of high-cost and low time efficiency of in vivo DNT tests, in vitro or in silico tests are the proposed alternatives, but it is unlikely that the results of such tests would reflect changes in higher brain functions. Accordingly, the current DNT test guidelines need to be revised to avoid overlooking or neglecting the occurrence of DNT induced by exposure to low doses of chemicals. This review also proposes the introduction of novel in vivo DNT testing methods in light of a cost-performance analysis.

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

    Energy Technology Data Exchange (ETDEWEB)

    Martin, C.W.

    1996-12-01

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

  7. Flow Test to Predict Early Hypotony and Hypertensive Phase After Ahmed Glaucoma Valve (AGV) Surgical Implantation.

    Science.gov (United States)

    Cheng, Jason; Beltran-Agullo, Laura; Buys, Yvonne M; Moss, Edward B; Gonzalez, Johanna; Trope, Graham E

    2016-06-01

    To assess the validity of a preimplantation flow test to predict early hypotony [intraocular pressure (IOP)≤5 mm Hg on 2 consecutive visits and hypertensive phase (HP) (IOP>21 mm Hg) after Ahmed Glaucoma Valve (AGV) implantation. Prospective interventional study on patients receiving an AGV. A preimplantation flow test using a gravity-driven reservoir and an open manometer was performed on all AGVs. Opening pressure (OP) and closing pressure (CP) were defined as the pressure at which fluid was seen to flow or stop flowing through the AGV, respectively. OP and CP were measured twice per AGV. Patients were followed for 12 weeks. In total, 20 eyes from 19 patients were enrolled. At 12 weeks the mean IOP decreased from 29.2±9.1 to 16.8±5.2 mm Hg (PAGV OP was 17.5±5.4 mm Hg and the mean CP was 6.7±2.3 mm Hg. Early (within 2 wk postoperative) HP occurred in 37% and hypotony in 16% of cases. An 18 mm Hg cutoff for the OP gave a sensitivity of 0.71, specificity of 0.83, positive predictive value of 0.71, and negative predictive value of 0.83 for predicting an early HP. A 7 mm Hg cutoff for the CP yielded a sensitivity of 1.0, specificity of 0.38, positive predictive value of 0.23, and negative predictive value of 1.0 for predicting hypotony. Preoperative OP and CP may predict early hypotony or HP and may be used as a guide as to which AGV valves to discard before implantation surgery.

  8. Assessment of cardiovascular function following transcatheter aortic valve implantation based on six-minute walk test.

    Science.gov (United States)

    Chodór, Piotr; Wilczek, Krzysztof; Zielińska, Teresa; Przybylski, Roman; Głowacki, Jan; Włoch, Łukasz; Zembala, Marian; Kalarus, Zbigniew

    2017-01-01

    Transcatheter aortic valve implantation (TAVI) is presently a recognized treatment mo-dality for patients with severe aortic stenosis ineligible for surgery. It reduces mortality as compared to the conservative treatment. It is further expected from this therapy to improve quality of life by improving of the cardiovascular function performance. The aim of this study is to compare patients' cardiovascular system efficiency in the 6-minute walk test (6MWT) made before and after TAVI and at the 6-12-month follow-up. From January 2009 until February 2012, in the Silesian Center for Heart Diseases in Zabrze, TAVI was performed in 104 patients. Eighty-two patients who underwent 6MWT before surgery were qualified for the analysis. The average age of the patients was 76.0 ± 9.17 years, women made 45.1%. The risk of surgical treatment according to the Logistic Euroscore averaged 22.76 ± 12.63%, and by the Society of Thoracic Surgeons - 5.55 ± 3.34%. The 6MWT was performed within 1 month before the TAVI procedure, up to a month after the procedure and during the 6-12-month follow-up. The 6-minute walk test after TAVI was performed by 64 patients, and after 6-12 month follow-up by 46 patients. The average distance in 6MWT increased from 268.4 ± 89.0 m before treat-ment to 290.0 ± 98.2 m after the procedure (p = 0.008) and 276.1 ± 93.5 m to 343.1 ± 96.7 m after 6-12 months (p < 0.0001). Transcatheter aortic valve implantation procedures significantly improve function of the cardiovascular system evaluated by the 6MWT in 1- and 6-12-month observations. (Cardiol J 2017; 24, 2: 167-175).

  9. The Finite Deformation Dynamic Sphere Test Problem

    Energy Technology Data Exchange (ETDEWEB)

    Versino, Daniele [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Brock, Jerry Steven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-02

    In this manuscript we describe test cases for the dynamic sphere problem in presence of finite deformations. The spherical shell in exam is made of a homogeneous, isotropic or transverse isotropic material and elastic and elastic-plastic material behaviors are considered. Twenty cases, (a) to (t), are thus defined combining material types and boundary conditions. The inner surface radius, the outer surface radius and the material's density are kept constant for all the considered test cases and their values are ri = 10mm, ro = 20mm and p = 1000Kg/m3 respectively.

  10. Testing of RPMI-1640 as a Nutrient Medium for Fresh Semilunar Valve Storage.

    Science.gov (United States)

    1979-01-01

    Ventriculograms of valved conduit implants in the heart b . . .. . . . . . . . . .• . . . . . . . * * . . . 44 c . . . . . . . . . . . . . . . 9 * . . . 45...where radiopaque dye was injected and a ventriculogram was recorded. 28 The catheter was then completely withdrawn and the vein tied. The animal was...in good condition. Figure 9 shows a ventriculogram demonstrating the valved conduit to be functional. One dog (#7) died during the catheterization

  11. 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.

  12. Anticoagulant independent mechanical heart valves: viable now or still a distant holy grail.

    Science.gov (United States)

    Chaux, Aurelio; Gray, Richard J; Stupka, Jonathan C; Emken, Michael R; Scotten, Lawrence N; Siegel, Rolland

    2016-12-01

    Valvular heart disease remains a large public health problem for all societies; it attracts the attention of public health organizations, researchers and governments. Valve substitution is an integral part of the treatment for this condition. At present, the choice of valve prosthesis is either tissue or mechanical. Tissue valves have become increasingly popular in spite of unresolved problems with durability, hemodynamics, cost and need for anticoagulation therapy. As a consequence, mechanical valve innovation has virtually ceased; the last successful mechanical design is 25 years old. We postulate that with improved technology, knowledge and experience gained over the last quarter century, the best possible solution to the problem of valve substitution can be achieved with a mechanical valve that is anticoagulant independent, durable, hemodynamically and cost efficient. At present, it is possible to design, test and produce a valve that can accomplish these goals.

  13. Options for Heart Valve Replacement

    Science.gov (United States)

    ... valve: Aortic regurgitation , (sometimes referred to as aortic insufficiency) is another common valve problem that may require ... allows oxygenated blood to flow backwards into the lungs instead of continuing through the heart as it ...

  14. 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

  15. Use of expert judgment in the development and evaluation of risk-based inservice testing strategies for pumps and valves

    Energy Technology Data Exchange (ETDEWEB)

    McAllister, W.J.; Perdue, R.K.; Balkey, K.R.; Closky, N.B. [and others

    1996-12-01

    This paper describes a rigorous approach for quantitatively evaluating inservice testing effectiveness that evolved from two pilot plant studies. These studies prototyped methodologies for designing and selecting inservice testing (IST) strategies in a manner structured to insure that the targeted components will perform their required safety functions while minimizing life cycle inservice testing costs. The paper concentrates on the use of expert judgment in developing test effectiveness measures that move risk-based methods beyond ranking to optimization of plant IST programs. Selected results for check valves and pumps are shown to illustrate the practical significance of the approach.

  16. Proceedings of the Third NRC/ASME Symposium on Valve and Pump Testing. Volume 2, Session 3A--Session 4B

    Energy Technology Data Exchange (ETDEWEB)

    1994-07-01

    The 1994 Symposium on Valve and Pump Testing, jointly sponsored by the Board of Nuclear Codes and Standards of the American Society of Mechanical Engineers and by the Nuclear Regulatory Commission, provides a forum for the discussion of current programs and methods for inservice testing and motor-operated valve testing at nuclear power plants. The symposium also provides an opportunity to discuss the need to improve that testing in order to help ensure the reliable performance of pumps and valves. The participation of industry representatives, regulators, and consultants results in the discussion of a broad spectrum of ideas and perspectives regarding the improvement of inservice testing of pumps and valves at nuclear power plants. Individual papers have been cataloged separately.

  17. Proceedings of the Third NRC/ASME Symposium on Valve and Pump Testing. Session 1A--Session 2C: Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    1994-07-01

    The 1994 Symposium on Valve and Pump Testing, jointly sponsored by the Board of Nuclear Codes and Standards of the American Society of Mechanical Engineers and by the Nuclear Regulatory Commission, provides a forum for the discussion of current programs and methods for inservice testing and motor-operated valve testing at nuclear power plants. The symposium also provides an opportunity to discuss the need to improve that testing in order to help ensure the reliable performance of pumps and valves. The participation of industry representatives, regulators, and consultants results in the discussion of a broad spectrum of ideas and perspectives regarding the improvement of inservice testing of pumps and valves at nuclear power plants. This document, Volume 1, covers sessions 1A through session 2C. The individual papers have been cataloged separately.

  18. St Jude Epic heart valve bioprostheses versus native human and porcine aortic valves - comparison of mechanical properties.

    Science.gov (United States)

    Kalejs, Martins; Stradins, Peteris; Lacis, Romans; Ozolanta, Iveta; Pavars, Janis; Kasyanov, Vladimir

    2009-05-01

    The major problem with heart valve bioprostheses made from chemically treated porcine aortic valves is their limited longevity caused by gradual deterioration, which has a causal link with valve tissue mechanical properties. To our best knowledge, there are no published studies on the mechanical properties of modern, commercially available bioprostheses comparing them to native human valves. The objective of this study is to determine the mechanical properties of St Jude Epic bioprostheses and to compare them with native human and porcine aortic valves. Leaflets from eight porcine aortic valves and six Epic bioprostheses were analyzed using uni-axial tensile tests in radial and circumferential directions. Mechanical properties of human valves have been previously published by our group. Results are represented as mean values+/-S.D. Circumferential direction. Modulus of elasticity of Epic bioprostheses in circumferential direction at the level of stress 1.0 MPa is 101.99+/-58.24 MPa, 42.3+/-4.96 MPa for native porcine and 15.34+/-3.84 MPa for human aortic valves. Ultimate stress is highest for Epic bioprostheses 5.77+/-1.94 MPa, human valves have ultimate stress of 1.74+/-0.29 MPa and porcine 1.58+/-0.26 MPa. Ultimate strain in circumferential direction is highest for human valves 18.35+/-7.61% followed by 7.26+/-0.69% for porcine valves and 5.95+/-1.54% for Epic bioprostheses. Radial direction. Modulus of elasticity in radial direction is 9.18+/-1.81 MPa for Epic bioprostheses, 5.33+/-0.61 MPa for native porcine, and 1.98+/-0.15 MPa for human aortic valve leaflets. In the radial direction ultimate stress is highest for Epic bioprostheses 0.7+/-0.21 MPa followed by native porcine valves 0.55+/-0.11 MPa and 0.32+/-0.04 MPa for human valves. For human valves ultimate strain is 23.92+/-4.87%, for native porcine valves 8.57+/-0.8% and 7.92+/-1.74% for Epic bioprostheses. Epic bioprostheses have non-linear stress-strain behavior similar to native valve tissue, but they

  19. Problems With Section Two ITP TOEFL Test

    Directory of Open Access Journals (Sweden)

    Rizki Ananda

    2016-03-01

    Full Text Available This study was designed to investigate (1 the difficulties faced by EFL university students with section two of the ITP, and (2 whether part A or part B was more difficult for them and why. A number of 26 students from two different universities, Syiah Kuala University and the State Islamic University Ar-Raniry were the samples for the test. The data was obtained from a multiple choice questionnaire test consisting of 46 questions, each with 4 answers to choose from. The results showed that inversions (12%, subject-verb agreements (10%, adverb clause connectors (7%, passives (6%, reduced adjective clauses (5%, parallel structures (5% and use of verbs (5% were the most difficult questions for the students. Furthermore, they felt that part B was more difficult than part A, as finding an error in a sentence was harder than completing a sentence from a multiple choice. Furthermore, the length of questions in part A did not affect the amount of time the students spent to complete part A and did not cause them to panic. Also, unfamiliar words in part A were not regarded as a problem by the students. Hence, TOEFL teachers and trainers are highly encouraged to pay more attention to doing study exercises for the seven topics with the highest percentages above in part A and also to more practice for part B.

  20. Testing developmental pathways to antisocial personality problems

    OpenAIRE

    Diamantopoulou, S.; Verhulst, Frank; Ende, Jan

    2010-01-01

    textabstractThis study examined the development of antisocial personality problems (APP) in young adulthood from disruptive behaviors and internalizing problems in childhood and adolescence. Parent ratings of 507 children's (aged 6-8 years) symptoms of attention deficit hyperactivity disorder, oppositional defiant disorder, and anxiety, were linked to self-ratings of adolescents' (aged 14-16 years) symptoms of depression, substance use, conduct problems, and somatic problems, to predict self-...

  1. Valve Disease

    Science.gov (United States)

    ... See also on this site: Diseases of the Mitral Valve Diseases of the Aortic Valve Diseases of the Tricuspid ... most invasive option for the treatment of valve disease. During surgery, ... defects of the mitral valve. Replacement is used to treat any diseased ...

  2. Modeling the Mitral Valve

    Science.gov (United States)

    Kaiser, Alexander

    2016-11-01

    The mitral valve is one of four valves in the human heart. The valve opens to allow oxygenated blood from the lungs to fill the left ventricle, and closes when the ventricle contracts to prevent backflow. The valve is composed of two fibrous leaflets which hang from a ring. These leaflets are supported like a parachute by a system of strings called chordae tendineae. In this talk, I will describe a new computational model of the mitral valve. To generate geometry, general information comes from classical anatomy texts and the author's dissection of porcine hearts. An MRI image of a human heart is used to locate the tips of the papillary muscles, which anchor the chordae tendineae, in relation to the mitral ring. The initial configurations of the valve leaflets and chordae tendineae are found by solving solving an equilibrium elasticity problem. The valve is then simulated in fluid (blood) using the immersed boundary method over multiple heart cycles in a model valve tester. We aim to identify features and mechanisms that influence or control valve function. Support from National Science Foundation, Graduate Research Fellowship Program, Grant DGE 1342536.

  3. Application of RELAP5/MOD3.3 to Calculate Thermal Hydraulic Behavior of the Pressurizer Safety Valve Performance Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang Hyun; Kim, Young Ae; Oh, Seung Jong; Park, Jong Woon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

    2007-10-15

    The increase of the acceptance tolerance of Pressurizer Safety Valve (PSV) test is vital for the safe operation of nuclear power plants because the frequent tests may make the valves decrepit and become a cause of leak. Recently, Korea Hydro and Nuclear Power Company (KHNP) is building a PSV performance test facility to provide the technical background data for the relaxation of the acceptance tolerance of PSV including the valve pop-up characteristics and the loop seal dynamics (if the plant has the loop seal in the upstream of PSV). The discharge piping and supports must be designed to withstand severe transient hydrodynamic loads when the safety valve actuates. The evaluation of hydrodynamic loads is a two-step process: first the thermal hydraulic behavior in the piping must be defined, and then the hydrodynamic loads are calculated from the thermal hydraulic parameters such as pressure and mass flow. The hydrodynamic loads are used as input to the structural analysis.

  4. An Improved Differential Evolution Method Based on the Dynamic Search Strategy to Solve Dynamic Economic Dispatch Problem with Valve-Point Effects

    Directory of Open Access Journals (Sweden)

    Guangyu Chen

    2014-01-01

    Full Text Available An improved differential evolution (DE method based on the dynamic search strategy (IDEBDSS is proposed to solve dynamic economic dispatch problem with valve-point effects in this paper. The proposed method combines the DE algorithm with the dynamic search strategy, which improves the performance of the algorithm. DE is the main optimizer in the method proposed. While chaotic sequences are applied to obtain the dynamic parameter settings in DE, dynamic search strategy which consists of two steps, global search strategy and local search strategy, is used to improve algorithm efficiency. To accelerate convergence, a new infeasible solution handing method is adopted in the local search strategy; meanwhile, an orthogonal crossover (OX operator is added to the global search strategy to enhance the optimization search ability. Finally, the feasibility and effectiveness of the proposed methods are demonstrated by three test systems, and the simulation results reveal that the IDEBDSS method can obtain better solutions with higher efficiency than the standard DE and other methods reported in the recent literature.

  5. In-situ hot corrosion testing of candidate materials for exhaust valve spindles

    DEFF Research Database (Denmark)

    Bihlet, Uffe; Hoeg, Harro A.; Dahl, Kristian Vinter

    2011-01-01

    used, exhaust valve spindles in marine diesel engines are subjected to high temperatures and stresses as well as molten salt induced corrosion. To investigate candidate materials for future designs which will involve the HIP process, a spindle with Ni superalloy material samples inserted in a HIPd Ni49...

  6. Testing Developmental Pathways to Antisocial Personality Problems

    Science.gov (United States)

    Diamantopoulou, Sofia; Verhulst, Frank C.; van der Ende, Jan

    2010-01-01

    This study examined the development of antisocial personality problems (APP) in young adulthood from disruptive behaviors and internalizing problems in childhood and adolescence. Parent ratings of 507 children's (aged 6-8 years) symptoms of attention deficit hyperactivity disorder, oppositional defiant disorder, and anxiety, were linked to…

  7. Testing developmental pathways to antisocial personality problems

    NARCIS (Netherlands)

    S. Diamantopoulou; F.C. Verhulst (Frank); J. van der Ende (Jan)

    2010-01-01

    textabstractThis study examined the development of antisocial personality problems (APP) in young adulthood from disruptive behaviors and internalizing problems in childhood and adolescence. Parent ratings of 507 children's (aged 6-8 years) symptoms of attention deficit hyperactivity disorder,

  8. Sequential Testing Problems for Bessel Processes

    OpenAIRE

    Johnson, Peter; Peskir, Goran

    2018-01-01

    Consider the motion of a Brownian particle that takes place either in a two-dimensional plane or in three-dimensional space. Given that only the distance of the particle to the origin is being observed, the problem is to detect the true dimension as soon as possible and with minimal probabilities of the wrong terminal decisions. We solve this problem in the Bayesian formulation under any prior probability of the true dimension when the passage of time is penalised linearly.

  9. The improved Jellyfish Valve: durability enhancement with sufficient blood compatibility.

    Science.gov (United States)

    Iwasaki, Kiyotaka; Umezu, Mitsuo; Abe, Yusuke; Chinzei, Tsuneo; Isoyama, Takashi; Saito, Itsuro; Ishimaru, Mitsuhiko; Imachi, Kou

    2002-01-01

    The Jellyfish Valve is one of the most promising polymer valves for artificial hearts. The present problems to be solved are 1) how to prevent a membrane fracture and 2) how to eliminate a calcification, because both of these problems were observed in experiments with goats after 312 days and 414 days of pumping. Finite element analysis demonstrated that mechanical tensile strain induced in the membrane at valve closure was clearly consistent with the fracture location as well as calcification area in in vivo experiments. Based on this finding, a new valve seat with an additional concentric ring 14 mm in diameter and 0.5 mm in width was finally developed. The maximum strain was dramatically reduced to 52% by the design improvement. Moreover, accelerated fatigue tests demonstrated that the improved valve was 10 times more durable as compared with the original valve, which was equivalent to an in vivo duration of 8.3 years. In animal experiments, including 31 days and 46 days use in a total artificial heart (TAH), no thrombus was found despite the lack of anticoagulant or antiplatelet therapies. These results indicate that the improved Jellyfish Valve might be one of the most durable polymer valves, able to perform in artificial hearts for a long period of time.

  10. Radionuclide esophageal transit test to detect esophageal disorders in patients with mitral valve prolapse

    Energy Technology Data Exchange (ETDEWEB)

    Kao Chiahung [Dept. of Nuclear Medicine, Taichung Veterans General Hospital (Taiwan); Tsai Shihchuan [Dept. of Nuclear Medicine, Show-Chwan Memorial Hospital, Changhua (Taiwan); Hsieh Jihfang [Dept. of Nuclear Medicine, Chi-Mei Foundation Hospital, Tainan (Taiwan); Ho Yungjen [Dept. of Radiology, Jen-Ai Hospital, Taichung (Taiwan); Ding Hueischjy [Dept. of Nuclear Medicine, Kaohsiung Medicine Coll. (Taiwan)

    2000-06-01

    Aim: The origin of chest discomfort in patients with mitral valve prolapse (MVP) is controversial. Our aim was to prospectively determine the incidence of esophageal disorders in MVP patients with or without chest pain. Methods: Twenty-five MVP patients with chest pain (group A) and 25 MVP patients without chest pain (group B) underwent evaluation of esophageal motility. None of the total of 50 MVP patients had significant coronary artery disease on cardiac catheterization. Esophageal motility including esophageal mean transit time (MTT), residual fraction (RF), and retrograde index (RI) was analyzed by the radionuclide esophageal transit test (RETT). Results: In comparison with 25 age and sex-matched healthy volunteers, the results showed that: (1) 19 patients in group A (76%) had abnormal RETT findings (48% of cases with prolonged MTT, 44% of cases with higher RF, and 60% of cases with higher RI); (2) 3 patients in group B (12%) had abnormal RETT findings (8% of cases with prolonged MTT, 4% of cases with higher RF, and 8% of cases with higher RI). In addition, mean values of MTT, RF, and RI in group A patients were significantly higher than in group B patients and healthy volunteers. Conclusion: We found that the chest pain in some MVP patients may be related to abnormal esophageal motility, based on the evidence from a simple and noninvasive RETT. (orig.) [German] Ziel: Die Ursache thorakaler Beschwerden bei Patienten mit Mitralklappenprolaps (MVP) wird kontrovers diskutiert. Wir bestimmten prospektiv die Haeufigkeit oesophagealer Stoerungen in MVP-Patienten mit oder ohne thorakale Beschwerden. Methode: Bei jeweils 25 MVP-Patienten mit thorakalen Beschwerden (Gruppe A) und 25 MVP-Patienten ohne thorakale Beschwerden (Gruppe B) wurde die oesophageale Motilitaet untersucht. Keiner der 50 MVP-Patienten hatte eine koronarangiographisch nachweisbare koronare Herzkrankheit. Mittels der Oesophagus-Funktionsszintigraphie (OeFZ) wurden oesophageale Motilitaet inklusive

  11. Leak testing in isolation in Almaraz NPP valves; Pruebas de fugas en valvulas de aislamiento en C.N. Almaraz

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Rocasolano, J.; Delgado Flores, E.

    2014-07-01

    The components, object of this paper are isolation valves of the containment of waste heat, injection safety and water extraction systems of sealing of the main pumps. A review and improvement of the methodology applied by means of an analysis of the provision and operation of certain systems, as well as practice followed by other plants in the US, aims to achieve a more effective testing program by reducing doses to staff, the generation of radioactive waste by drainage systems, and the risks of introduction of parts loose in the primary. (Author)

  12. Problems With Section Two ITP TOEFL Test

    National Research Council Canada - National Science Library

    Rizki Ananda

    2016-01-01

    ...) whether part A or part B was more difficult for them and why. A number of 26 students from two different universities, Syiah Kuala University and the State Islamic University Ar-Raniry were the samples for the test...

  13. Heart valve surgery

    Science.gov (United States)

    Valve replacement; Valve repair; Heart valve prosthesis; Mechanical valves; Prosthetic valves ... can relieve your symptoms and prolong your life. Mechanical heart valves do not often fail. However, blood clots can ...

  14. Test problem construction for single-objective bilevel optimization.

    Science.gov (United States)

    Sinha, Ankur; Malo, Pekka; Deb, Kalyanmoy

    2014-01-01

    In this paper, we propose a procedure for designing controlled test problems for single-objective bilevel optimization. The construction procedure is flexible and allows its user to control the different complexities that are to be included in the test problems independently of each other. In addition to properties that control the difficulty in convergence, the procedure also allows the user to introduce difficulties caused by interaction of the two levels. As a companion to the test problem construction framework, the paper presents a standard test suite of 12 problems, which includes eight unconstrained and four constrained problems. Most of the problems are scalable in terms of variables and constraints. To provide baseline results, we have solved the proposed test problems using a nested bilevel evolutionary algorithm. The results can be used for comparison, while evaluating the performance of any other bilevel optimization algorithm. The code related to the paper may be accessed from the website http://bilevel.org .

  15. Problem-Solving Test: Restriction Endonuclease Mapping

    Science.gov (United States)

    Szeberenyi, Jozsef

    2011-01-01

    The term "restriction endonuclease mapping" covers a number of related techniques used to identify specific restriction enzyme recognition sites on small DNA molecules. A method for restriction endonuclease mapping of a 1,000-basepair (bp)-long DNA molecule is described in the fictitious experiment of this test. The most important fact needed to…

  16. American History's Problem with Standardized Testing

    Science.gov (United States)

    McCoog, Ian J.

    2005-01-01

    This article looks at current research concerning how students best learn the discipline of history, commentaries both in favor of and against standardized testing, and basic philosophical beliefs about the discipline. It explains methods of how to incorporate differentiated lessons and performance based assessments to NCLB standards and…

  17. Test problems for radiation and radiation-hydrodynamics codes

    Science.gov (United States)

    Ensman, Lisa

    1994-01-01

    A number of test problems for radiation and radiation-hydrodynamics computer codes are described. These include evolution to radiative equilibrium, cooling from radiative equilibrium, subcritical and supercritical radiating shocks, and a radiating blast wave in a power-law density distribution. For each test problem, example input parameters and plots of the results are presented. Some test problems for pure hydrodynamics are also suggested. The radiation-hydrodynamics code used to perform the example test problems and the equations it solves are described in some detail.

  18. Surface inspection problems in thermoelectric testing

    Directory of Open Access Journals (Sweden)

    Abouellail Ahmed

    2017-01-01

    Full Text Available This paper demonstrates the outcome of experimental studies on thermoelectric characteristics of thermocouples. Measurements were carried out using different types of thermocouples; each studied alone then investigated when they are connected in parallel, in order to simulate the imperfect nature of the various multi-contact surface of the tested object. The investigated types were Chromel-Alumel and Nichrome-Constantan. The thermoelectric characteristics were measured at the temperature range 160° − 400° Celsius, in order to identify the best operating temperature for the hot electrode. Furthermore, the load resistance is another important factor that has been investigated and therefore varied from 1Ω to 10kΩ, in order to determine its effect on the electrical characteristics of thermocouples. Accordingly, these characteristics will help defining the requirements for an optimum thermoelectric testing.

  19. Static Test Compaction As A Minimum Covering Problem | Boateng ...

    African Journals Online (AJOL)

    Large numbers of test stimuli impact on the time and cost of test application. Hence there is the need to keep numbers of test stimuli low while maintaining as high fault coverage as possible. In this paper, static compaction of test stimuli is seen as a minimization problem. The task of static compaction of a set of test stimuli ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Zanner, G.; Kradepohl, P.

    1996-12-01

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

  1. Group Testing: Four Student Solutions to a Classic Optimization Problem

    Science.gov (United States)

    Teague, Daniel

    2006-01-01

    This article describes several creative solutions developed by calculus and modeling students to the classic optimization problem of testing in groups to find a small number of individuals who test positive in a large population.

  2. STATIC TEST COMPACTION AS A MINIMUM COVERING PROBLEM

    African Journals Online (AJOL)

    DEPT OF AGRICULTURAL ENGINEERING

    ABSTRACT. Large numbers of test stimuli impact on the time and cost of test application. Hence there is the need to keep numbers of test stimuli low while maintaining as high fault coverage as possible. In this paper, static compaction of test stimuli is seen as a minimization problem. The task of static compaction of a set of ...

  3. Valve reconstruction for congenital mitral valve disease.

    Science.gov (United States)

    Quinonez, Luis G; Del Nido, Pedro J

    2015-01-01

    The surgical treatment of mitral valve disease in children is a challenging problem. Mitral stenosis and regurgitation may occur in isolation or together. Mitral valve repair is almost always preferable to replacement. Mitral valve replacement is not an ideal alternative to repair due to limitations of size, growth, structural valve degeneration, anticoagulation and poor survival. Surgical repair of congenital mitral stenosis must address the multiple levels of obstruction, including resection of the supramitral ring, thinning of leaflets and mobilization of the subvalvular apparatus. Sometimes leaflet augmentation is required. Repair of mitral regurgitation in children may involve simple cleft closures, edge-to-edge repairs, triangular resections and annuloplasties. Techniques used in adults, such as annuloplasty bands or artificial chords, may not be appropriate for children. Overall, an imperfect mitral valve repair may be more acceptable than the negative consequences of a replacement in a child. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  4. ST-Segment Depression in Hyperventilation Indicates a False Positive Exercise Test in Patients with Mitral Valve Prolapse

    Directory of Open Access Journals (Sweden)

    Andreas P. Michaelides

    2010-01-01

    Full Text Available Objectives. Mitral valve prolapse (MVP is a known cause for false positive exercise test (ET. The purpose of this study was to establish additional electrocardiographic criteria to distinguish the false positive exercise results in patients with MVP. Methods. We studied 218 consecutive patients ( years, 103 males with MVP (according to echocardiographic study, and positive treadmill ET was performed due to multiple cardiovascular risk factors or angina-like symptoms. A coronary angiography was performed to detect coronary artery disease (CAD. Results. From 218 patients, 90 (group A presented with normal coronary arteries according to the angiography (false positive ET while the rest 128 (group B presented with CAD. ST-segment depression in hyperventilation phase was present in 54 patients of group A (60% while only in 14 patients of group B (11%, . Conclusions. Presence of ST-segment depression in hyperventilation phase favors a false positive ET in patients with MVP.

  5. Effects of dependence in high-dimensional multiple testing problems

    NARCIS (Netherlands)

    Kim, K.I.; van de Wiel, M.A.

    2008-01-01

    Background: We consider effects of dependence among variables of high-dimensional data in multiple hypothesis testing problems, in particular the False Discovery Rate (FDR) control procedures. Recent simulation studies consider only simple correlation structures among variables, which is hardly

  6. 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.

  7. Performance of Various Metaheuristic Techniques for Economic Dispatch Problem with Valve Point Loading Effects and Multiple Fueling Options

    Directory of Open Access Journals (Sweden)

    Ijaz Ahmed

    2014-01-01

    Full Text Available The paper presents the metaheuristic approaches based on pattern search and simulated annealing hybridized with sequential quadratic programming, a powerful nonlinear adaptive technique for estimation of the finest combination of generated power in a given system at lowest operating cost while sustaining the operating condition of system efficiently. The fuel cost is minimized by satisfying the nonlinear operating conditions of thermal units mainly based on generation capacity constraints, generator ramp limit, power balance constraints, and valve point loading effect and by keeping in view the prohibited operating zones, respectively. About the optimization, a comparative study is made for pattern search (PS and simulated annealing (SA, as a viable global search technique and sequential quadratic programming, an efficient local optimizer and their hybrid versions. The applicability, stability, and reliability of the designed approaches are validated through comprehensive statistical analysis based on Monte Carlo simulations.

  8. Conceptual design and selection of deposited metal on the valve seat for the high temperature isolation valve in the HTTR hydrogen production system (contract research)

    Energy Technology Data Exchange (ETDEWEB)

    Nishihara, Tetsuo; Iwatsuki, Jin [Department of Advanced Nuclear Heat Technology, Oarai Research Establishment, Japan Atomic Energy Research Institute, Oarai, Ibaraki (Japan)

    1999-11-01

    In the HTTR hydrogen production system a high temperature isolation valve should be provided outside the penetration of containment vessel on the secondary helium loop. As the secondary helium gas is at temperature of 905degC and pressure of 4.1 MPa, there is not any available isolation valve used under such conditions. Once demonstration test of high temperature isolation valve was carried out in the ERANS project. Tested valve could meet the basic design requirements but some problems remained. In this report a conceptual design of the high temperature isolation valve is performed in consideration of resolving these problems. The structural reliability is confirmed by the three-dimensional stress analysis. With respect to the deposited metal on valve seat, a screening test is done to observe the basic properties of candidate metals. From these results, it is shown that Stellite alloy that is used in practical valve has a possibility of the separation at welding layer and carbon diffusion from deposited metal into the base metal. Nickel-base super alloy has a possibility of internal and intergranular oxidation due to contained Al and Ti. Therefore, detail metallographical and mechanical tests for long period are planned to select the adequate deposited metal. (author)

  9. Butterfly valve of all rubber lining type

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Shosaku; Nakatsuma, Sumiya (Kubota Ltd., Osaka (Japan)); Sasaki, Iwao; Aoki, Naoshi

    1982-08-01

    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.

  10. Simulation and Experimental Testing of an Actuator for a Fast Switching On-Off Valve Suitable to Efficient Displacement Machines

    DEFF Research Database (Denmark)

    Roemer, Daniel Beck; Johansen, Per; Bech, Michael Møller

    2014-01-01

    for the valve design process. In this paper simulation of such fast switching valve is presented and the transient actuator performance is experimentally validated against transient Finite Element Analysis (FEA). Models predict a switching time of approximately 1ms for the valve and a pressure loss of 0.5 bar......Digital Displacement (DD) fluid power machines are upcoming technology, improving the efficiency compared to traditional variable displacement machines, especially at low displacements where currently available fluid power pumps/motors suffer from mediocre efficiency. This efficiency improvement...

  11. 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.

  12. Hypothesis Designs for Three-Hypothesis Test Problems

    OpenAIRE

    Yan Li; Xiaolong Pu

    2010-01-01

    As a helpful guide for applications, the alternative hypotheses of the three-hypothesis test problems are designed under the required error probabilities and average sample number in this paper. The asymptotic formulas and the proposed numerical quadrature formulas are adopted, respectively, to obtain the hypothesis designs and the corresponding sequential test schemes under the Koopman-Darmois distributions. The example of the normal mean test shows that our methods are qu...

  13. Testing a Comprehensive Model for Measuring Problem Solving and Problem Posing Skills of Primary Pupils

    Science.gov (United States)

    Charalambous, Charalambos; Kyriakides, Leonidas; Philippou, George

    2003-01-01

    The study reported in this paper is an attempt to develop a comprehensive model of measuring problem solving and posing (PSP) skills based on Marshall's schema theory (ST). A battery of tests on PSP skills was administered to 5th and 6th grade Cypriot students (n=2519). The Rasch model was used and a scale was created for the battery of tests and…

  14. 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...... similar to the one achieved by the expensive and time-consuming CFD calculations. So CFD is only used in case of entirely new designs or where a very detailed knowledge of the flow is required. Even though rules of thumb are useful for those, who have developed them, Danfoss needs an objective and general...

  15. A pattern of test findings predicting attention problems at school.

    Science.gov (United States)

    Korkman, M; Peltomaa, K

    1991-08-01

    The aim of this study was to identify different types of neuropsychological test profiles that would predict attention problems at school. Forty-six children with mild developmental disorders, among whom a high frequency of attention deficit disorder (ADD) was expected, were examined just before they started school. The tests were mainly drawn from a new assessment, called NEPSY, and corresponded to the various components of attention. The test profiles were grouped with the aid of a Q-type factor analysis into five subgroups. The test profiles of two of the subgroups were suggestive of attention deficits. The predictions were based on difficulties in tests aimed to evaluate impulse control, sustained attention, and selective attention. As such findings were found in both of the subgroups they were collapsed into one. Half a year later the collapsed subgroups were found to have a higher frequency of attention problems at school than the other three subgroups.

  16. Ability evaluation by binary tests: Problems, challenges & recent advances

    Science.gov (United States)

    Bashkansky, E.; Turetsky, V.

    2016-11-01

    Binary tests designed to measure abilities of objects under test (OUTs) are widely used in different fields of measurement theory and practice. The number of test items in such tests is usually very limited. The response to each test item provides only one bit of information per OUT. The problem of correct ability assessment is even more complicated, when the levels of difficulty of the test items are unknown beforehand. This fact makes the search for effective ways of planning and processing the results of such tests highly relevant. In recent years, there has been some progress in this direction, generated by both the development of computational tools and the emergence of new ideas. The latter are associated with the use of so-called “scale invariant item response models”. Together with maximum likelihood estimation (MLE) approach, they helped to solve some problems of engineering and proficiency testing. However, several issues related to the assessment of uncertainties, replications scheduling, the use of placebo, as well as evaluation of multidimensional abilities still present a challenge for researchers. The authors attempt to outline the ways to solve the above problems.

  17. An improved gate valve for critical applications in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Kalsi, M.S.; Alvarez, P.D.; Wang, J.K.; Somagyi, D. [Kalsi Engineering, Inc., Sugar Land, TX (United States)] [and others

    1996-12-01

    U.S. Nuclear Regulatory Commission Generic Letters 89-10 for motor-operated valves (MOVs) and 95-07 for all power-operated valves document in detail the problems related to the performance of the safety-related valves in nuclear power plants. The problems relate to lack of reliable operation under design basis conditions including higher than anticipated stem thrust, unpredictable valve behavior, damage to the valve internals under blowdown/high flow conditions, significant degradation of performance when cycled under AP and flow, thermal binding, and pressure locking. This paper describes an improved motor-operated flexible wedge gate valve design, the GE Sentinel Valve, which is the outcome of a comprehensive and systematic development effort undertaken to resolve the issues identified in the NRC Generic Letters 89-10 and 95-07. The new design provides a reliable, long-term, low maintenance cost solution to the nuclear power industry. One of the key features incorporated in the disc permits the disc flexibility to be varied independently of the disc thickness (pressure boundary) dictated by the ASME Section III Pressure Vessel & Piping Code stress criteria. This feature allows the desired flexibility to be incorporated in the disc, thus eliminating thermal binding problems. A matrix of analyses was performed using finite element and computational fluid dynamics approaches to optimize design for stresses, flexibility, leak-tightness, fluid flow, and thermal effects. The design of the entire product line was based upon a consistent set of analyses and design rules which permit scaling to different valve sizes and pressure classes within the product line. The valve meets all of the ASME Section III Code design criteria and the N-Stamp requirements. The performance of the valve was validated by performing extensive separate effects and plant in-situ tests. This paper summarizes the key design features, analyses, and test results.

  18. Group Work Tests for Context-Rich Problems

    Science.gov (United States)

    Meyer, Chris

    2016-05-01

    The group work test is an assessment strategy that promotes higher-order thinking skills for solving context-rich problems. With this format, teachers are able to pose challenging, nuanced questions on a test, while providing the support weaker students need to get started and show their understanding. The test begins with a group discussion phase, when students are given a "number-free" version of the problem. This phase allows students to digest the story-like problem, explore solution ideas, and alleviate some test anxiety. After 10-15 minutes of discussion, students inform the instructor of their readiness for the individual part of the test. What follows next is a pedagogical phase change from lively group discussion to quiet individual work. The group work test is a natural continuation of the group work in our daily physics classes and helps reinforce the importance of collaboration. This method has met with success at York Mills Collegiate Institute, in Toronto, Ontario, where it has been used consistently for unit tests and the final exam of the grade 12 university preparation physics course.

  19. A new powerful nonparametric rank test for ordered alternative problem.

    Directory of Open Access Journals (Sweden)

    Guogen Shan

    Full Text Available We propose a new nonparametric test for ordered alternative problem based on the rank difference between two observations from different groups. These groups are assumed to be independent from each other. The exact mean and variance of the test statistic under the null distribution are derived, and its asymptotic distribution is proven to be normal. Furthermore, an extensive power comparison between the new test and other commonly used tests shows that the new test is generally more powerful than others under various conditions, including the same type of distribution, and mixed distributions. A real example from an anti-hypertensive drug trial is provided to illustrate the application of the tests. The new test is therefore recommended for use in practice due to easy calculation and substantial power gain.

  20. The measurand problem in infrared breath alcohol testing

    Science.gov (United States)

    Vosk, Ted

    2012-02-01

    Measurements are made to determine the value of a quantity known as a measurand. The measurand is not always the quantity subject to measurement, however. Often, a distinct quantity will be measured and related to the measurand through a measurement function. When the identities of the measurand and the quantity actually measured are not well defined or distinguished, it can lead to the misinterpretation of results. This is referred to as the measurand problem. The measurand problem can present significant difficulties when the law and not science determines the measurand. This arises when the law requires that a particular quantity be measured. Legal definitions are seldom as rigorous or complete as those utilized in science. Thus, legally defined measurands often fall prey to the measurand problem. An example is the measurement of breath alcohol concentration by infrared spectroscopy. All 50 states authorize such tests but the measurand differs by jurisdiction. This leads to misinterpretation of results in both the forensic and legal communities due to the measurand problem with the consequence that the innocent are convicted and guilty set free. Correct interpretation of breath test results requires that the measurand be properly understood and accounted for. I set forth the varying measurands defined by law, the impact these differing measurands have on the interpretation of breath test results and how the measurand problem can be avoided in the measurement of breath alcohol concentration.

  1. Considering transmission loss for an economic dispatch problem without valve-point loading using an EP-EPSO algorithm

    OpenAIRE

    PANDIAN, Sevugarathinam MUTHU VIJAYA; THANUSHKODI, Keppanagowder

    2014-01-01

    Economic dispatch (ED) is one of the most important optimization problems in a power system. The objective of ED is sharing the power demand among the online generators while keeping the minimum cost of generation as a constraint. The aim of this paper is to operate an electric power system as economically as possible within its security limits. This paper proposes the following 2 new particle swarm optimization (PSO) algorithms to solve a nonconvex economic dispatch problem: an efficien...

  2. Feasibility Testing for Dial-a-Ride Problems

    DEFF Research Database (Denmark)

    Haugland, Dag; Ho, Sin C.

    2010-01-01

    Hunsaker and Savelsbergh have proposed an algorithm for testing feasibility of a route in the solution to the dial-a-ride problem. The constraints that are checked are load capacity constraints, time windows, ride time bounds and wait time bounds. The algorithm has linear running time. By virtue ...

  3. Mammalian Toxicology Testing: Problem Definition Study, Personnel Plan.

    Science.gov (United States)

    1981-03-01

    supporting documents. The Contrzt title, MAMMALIAN TOXICO - LOGY TESTING: PROBLEM DEFINITION STUDY, is the main title for all the reports. Individual...Agency" (Conservation Founda- tion 1978) it was estimated that there are approximately 2,700 senior toxico - logists and a total of 5,000 toxicologists in

  4. Feasibility testing for dial-a-ride problems

    DEFF Research Database (Denmark)

    Haugland, Dag; Ho, Sin C.

    Hunsaker and Savelsbergh have proposed an algorithm for testing feasibility of a route in the solution to the dial-a-ride problem. The constraints that are checked are load capacity constraints, time windows, ride time bounds and wait time bounds. The algorithm has linear running time. By virtue...

  5. In vitro evaluation of implantation depth in valve-in-valve using different transcatheter heart valves.

    Science.gov (United States)

    Simonato, Matheus; Azadani, Ali N; Webb, John; Leipsic, Jonathon; Kornowski, Ran; Vahanian, Alec; Wood, David; Piazza, Nicolo; Kodali, Susheel; Ye, Jian; Whisenant, Brian; Gaia, Diego; Aziz, Mina; Pasala, Tilak; Mehilli, Julinda; Wijeysundera, Harindra C; Tchetche, Didier; Moat, Neil; Teles, Rui; Petronio, Anna Sonia; Hildick-Smith, David; Landes, Uri; Windecker, Stephan; Arbel, Yaron; Mendiz, Oscar; Makkar, Raj; Tseng, Elaine; Dvir, Danny

    2016-09-18

    Transcatheter heart valve (THV) implantation in failed bioprosthetic valves (valve-in-valve [ViV]) offers an alternative therapy for high-risk patients. Elevated post-procedural gradients are a significant limitation of aortic ViV. Our objective was to assess the relationship between depth of implantation and haemodynamics. Commercially available THVs used for ViV were included in the analysis (CoreValve Evolut, SAPIEN XT and the Portico valve). THVs were implanted in small surgical valves (label size 19 mm) to simulate boundary conditions. Custom-mounted pulse duplicators registered relevant haemodynamic parameters. Twenty-eight experiments were performed (13 CVE, 5 SXT and 10 Portico). Ranges of depth of implantation were: CVE: -1.2 mm to 15.7 mm; SXT: -2.2 mm to 7.5 mm; Portico: 1.4 mm to 12.1 mm. Polynomial regression established a relationship between depth of implantation and valvular mean gradients (CVE: p<0.001; SXT: p=0.01; Portico: p=0.002), as well as with EOA (CVE: p<0.001; SXT: p=0.02; Portico valve: p=0.003). In addition, leaflet coaptation was better in the high implantation experiments for all valves. The current comprehensive bench testing assessment demonstrates the importance of high device position for the attainment of optimal haemodynamics during aortic ViV procedures.

  6. Study on decellularized porcine aortic valve/poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) hybrid heart valve in sheep model.

    Science.gov (United States)

    Wu, Song; Liu, Ying-Long; Cui, Bin; Qu, Xiang-Hua; Chen, Guo-Qiang

    2007-09-01

    To overcome shortcomings of current heart valve prostheses, novel hybrid valves were fabricated from decellularized porcine aortic valves coated with poly (3-hydroxybutyrate-co-3-hydroxyhexanoate [PHBHHx]). In the mechanical test in vitro, the biomechanical performance of hybrid valve was investigated. In an in vivo study, hybrid valve conduits were implanted in pulmonary position in sheep without cardiopulmonary bypass. Uncoated grafts were used as control. The valves were explanted and examined histologically and biochemically 16 weeks after surgery. The hybrid valve conduits maintained original shapes, were covered by a confluent layer of cells, and had less calcification than uncoated control. The mechanical test in vitro revealed that PHBHHx coating improved tensile strength. The results in vivo indicated that PHBHHx coating reduced calcification and promoted the repopulation of hybrid valve with the recipient's cells resembling native valve tissue. The hybrid valve may provide superior valve replacement with current techniques.

  7. Testing Homogeneity in a Semiparametric Two-Sample Problem

    Directory of Open Access Journals (Sweden)

    Yukun Liu

    2012-01-01

    Full Text Available We study a two-sample homogeneity testing problem, in which one sample comes from a population with density f(x and the other is from a mixture population with mixture density (1−λf(x+λg(x. This problem arises naturally from many statistical applications such as test for partial differential gene expression in microarray study or genetic studies for gene mutation. Under the semiparametric assumption g(x=f(xeα+βx, a penalized empirical likelihood ratio test could be constructed, but its implementation is hindered by the fact that there is neither feasible algorithm for computing the test statistic nor available research results on its theoretical properties. To circumvent these difficulties, we propose an EM test based on the penalized empirical likelihood. We prove that the EM test has a simple chi-square limiting distribution, and we also demonstrate its competitive testing performances by simulations. A real-data example is used to illustrate the proposed methodology.

  8. Experimental substantiation of the design of a prosthetic heart valve for «valve-in-valve» implantation

    Directory of Open Access Journals (Sweden)

    K. Yu. Klyshnikov

    2017-01-01

    Full Text Available The aim of the study was to perform a series of in vitro tests of a prototype of the developing heart valve prosthesis to evaluate its functional characteristics. Materials and methods. In this work we have used the frames and full prototypes of the prosthesis, consisting of a stent-like stainless steel support frame with mounted biological leaflets and cover. The authors evaluated the calculated and experimental forces necessary for the displacement of the sutureless implanted prosthesis using the test machine under uniaxial tension. The risk of defects and damages to the supporting framework as a result of implantation was evaluated by scanning electron microscopy. The hydrodynamic characteristics of the prosthesis were investigated under physiological conditions and «valvein-valve» implantation. Evaluation of the ergonomics and applicability of the proposed construction on the cadaver heart model of cattle was carried out. Results. As a result of the forces assessment, it was found that the force required to shear the prosthesis was 3.12 ± 0.37 N, while the calculated value was 1.7 N, which is significantly lower than the obtained value. The comparison of the images obtained with small and large magnifications demonstrated the absence of critical surface defects. Additional analysis under the super-large magnifications also did not reveal problem areas. During the hydrodynamic study, it was shown that the average transplant gradient increased slightly from 2.8–3.4 to 3.2–4.5 mm Hg for the initial prosthesis and the «valve-in-valve» complex, respectively. The decrease of the effective orifice area was 6–9% relative to the initial one. Evaluation of the implantation technique demonstrated the consistency of the approach: the use of the developed holder in combination with the balloon implantation system made it possible to position the prosthesis throughout the procedure. Conclusion. The series of tests demonstrates the consistency

  9. Hybrid Harmony Search Algorithm and Interior Point Method for Economic Dispatch with Valve-Point Effect

    Science.gov (United States)

    Sivasubramani, S.; Ahmad, Md. Samar

    2014-06-01

    This paper proposes a new hybrid algorithm combining harmony search (HS) algorithm and interior point method (IPM) for economic dispatch (ED) problem with valve-point effect. ED problem with valve-point effect is modeled as a non-linear, constrained and non-convex optimization problem having several local minima. IPM is a best non-linear optimization method for convex optimization problems. Since ED problem with valve-point effect has multiple local minima, IPM results in a local optimum solution. In order to avoid IPM getting trapped in a local optimum, a new evolutionary algorithm HS, which is good in global exploration, has been combined. In the hybrid method, HS is used for global search and IPM for local search. The hybrid method has been tested on three different test systems to prove its effectiveness. Finally, the simulation results are also compared with other methods reported in the literature.

  10. Pregnancy-induced remodeling of heart valves.

    Science.gov (United States)

    Pierlot, Caitlin M; Moeller, Andrew D; Lee, J Michael; Wells, Sarah M

    2015-11-01

    Recent studies have demonstrated remodeling of aortic and mitral valves leaflets under the volume loading and cardiac expansion of pregnancy. Those valves' leaflets enlarge with altered collagen fiber architecture, content, and cross-linking and biphasic changes (decreases, then increases) in extensibility during gestation. This study extends our analyses to right-sided valves, with additional compositional measurements for all valves. Valve leaflets were harvested from nonpregnant heifers and pregnant cows. Leaflet structure was characterized by leaflet dimensions, and ECM composition was determined using standard biochemical assays. Histological studies assessed changes in cellular and ECM components. Leaflet mechanical properties were assessed using equibiaxial mechanical testing. Collagen thermal stability and cross-linking were assessed using denaturation and hydrothermal isometric tension tests. Pulmonary and tricuspid leaflet areas increased during pregnancy by 35 and 55%, respectively. Leaflet thickness increased by 20% only in the pulmonary valve and largely in the fibrosa (30% thickening). Collagen crimp length was reduced in both the tricuspid (61%) and pulmonary (42%) valves, with loss of crimped area in the pulmonary valve. Thermomechanics showed decreased collagen thermal stability with surprisingly maintained cross-link maturity. The pulmonary leaflet exhibited the biphasic change in extensibility seen in left side valves, whereas the tricuspid leaflet mechanics remained largely unchanged throughout pregnancy. The tricuspid valve exhibits a remodeling response during pregnancy that is significantly diminished from the other three valves. All valves of the heart remodel in pregnancy in a manner distinct from cardiac pathology, with much similarity valve to valve, but with interesting valve-specific responses in the aortic and tricuspid valves. Copyright © 2015 the American Physiological Society.

  11. 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.

  12. Feasibility Testing for Dial-a-Ride Problems

    Science.gov (United States)

    Haugland, Dag; Ho, Sin C.

    Hunsaker and Savelsbergh have proposed an algorithm for testing feasibility of a route in the solution to the dial-a-ride problem. The constraints that are checked are load capacity constraints, time windows, ride time bounds and wait time bounds. The algorithm has linear running time. By virtue of a simple example, we show in this work that their algorithm is incorrect. We also prove that by increasing the time complexity by only a logarithmic factor, a correct algorithm is obtained.

  13. Procedural Tests of Anti-G Protective Devices. Volume I. Procedural Tests for Anti-G Valves

    Science.gov (United States)

    1979-12-01

    20 3.7 Data Collection Station Preamplifiers . . . .I-. - . . • 21 3.8 Strip-chart Recorders ...... ............ DC* 7A" ....... . . . . . 21 3.9...167 FIGURES Figure No. I SVT ? open-flow configuration .............. ........................... 10 2 SVTP dynamic test configuration... third set of SACM’s is run with a maximum suit volume (14 liters) and the minimum source pressure; the fourth set, with the minimum suit volume (6

  14. A New Method Solving Contact/Detach Problem in Fluid and Structure Interaction Simulation with Application in Modeling of a Safety Valve

    Directory of Open Access Journals (Sweden)

    Zheng Guo

    2010-01-01

    Full Text Available A new virtual baffle methodology is implemented to solve contact/detach problem which is often encountered in fluid and structure interaction simulations while using dynamic grids technique. The algorithm is based on tetrahedral unstructured grid, and a zero thickness baffle face is generated between actually contacted two objects. In computation process, this baffle face is divided into two parts representing convective and blocked area, respectively; the area of each part is calculated according to the actual displacement between the two objects. Convective part in a baffle face is treated as inner interface between cells, and on blocked part wall boundary condition is applied; so convective and blocking effect can be achieved on a single baffle face. This methodology can simulate real detaching process starting from contact, that is, zero displacement, while it has no restriction to minimum grid cell size. The methodology is then applied in modeling of a complicated safety valve opening process, involving multidisciplinary fluid and structure interaction and dynamic grids. The results agree well with experimental data, which proves that the virtual baffle method is successful.

  15. Valve's Way

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul; Dobrajska, Magdalena

    2015-01-01

    to what extent it represents a new blueprint for organization design, despite it being consistent with an “egalitarian Zeitgeist” (Puranam, 2014). In fact, managerial authority may be of increasing importance rather than the opposite (Guadalupe, Li, & Wulf, 2015). Thus, Valve is, and will remain...

  16. Vacuum Valve

    CERN Multimedia

    1974-01-01

    This valve was used in the Intersecting Storage Rings (ISR) to protect against the shock waves that would be caused if air were to enter the vacuum tube. Some of the ISR chambers were very fragile, with very thin walls - a design required by physicists on the lookout for new particles.

  17. Variable Valve Actuation

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Gutterman; A. J. Lasley

    2008-08-31

    the mechanism it was determined that the single cam design did not have enough flexibility to satisfy three critical OEM requirements simultaneously, (maximum valve lift variation, intake valve opening timing and valve closing duration), and a new approach would be necessary. After numerous internal design reviews including several with the OEM a dual cam design was developed that had the flexibility to meet all motion requirements. The second cam added complexity to the mechanism however the cost was offset by the deletion of the electric motor required in the previous design. New patent applications including detailed drawings and potential valve motion profiles were generated and alternate two cam designs were proposed and evaluated for function, cost, reliability and durability. Hardware was designed and built and testing of sample hardware was successfully completed on an engine test stand. The mechanism developed during the course of this investigation can be applied by Original Equipment Manufacturers, (OEM), to their advanced diesel engines with the ultimate goal of reducing emissions and improving fuel economy. The objectives are: (1) Develop an optimal, cost effective, variable valve actuation (VVA) system for advanced low temperature diesel combustion processes. (2) Design and model alternative mechanical approaches and down-select for optimum design. (3) Build and demonstrate a mechanism capable of application on running engines.

  18. Posture-independent piston valve: a novel valve mechanism that actuates based on intracranial pressure alone.

    Science.gov (United States)

    Medow, Joshua E; Luzzio, Christopher C

    2012-01-01

    Shunt valves are intended to maintain physiological intracranial pressure (ICP). A variety of mechanisms have been designed to accomplish this goal but have had limited success. Siphoning, in particular, has been a problem not effectively solved by proposed or manufactured valves. Poor control of ICP results in headache, neurological disturbances, decreased cognition, shunt malfunction, slit ventricles, subdural hematomas, decreased cranial volume, and maldevelopment. The authors of this study describe a prototype valve that was machined and tested ex vivo and that actuates based on ICP alone regardless of the presence of a siphon. Their object was to determine if a novel shunt mechanism that actuates perpendicular to the flow of fluid would eliminate the effect of siphoning in a valve for the treatment of hydrocephalus. A posture-independent piston valve (PIPV) was anchored to a graduated reservoir. Opening pressure was measured by noting the fluid level in the reservoir when the piston moved. Measurements were made using a 90-cm and a 120-cm water-filled siphon tube (1.3-mm standard distal catheter) to simulate an upright posture. A recumbent posture was simulated by the absence of a siphon. Opening pressure of the valve did not change regardless of the presence or absence of a water-filled siphon. The PIPV was triggered only by the pressure head at the inlet and did not actuate in the presence of a siphon, demonstrating proof of principle of the perpendicular actuating mechanism. The PIPV is a purely mechanical device that has practical application in the treatment of hydrocephalus.

  19. Recognizing the Symptoms of Worsening Heart Valve Disease

    Science.gov (United States)

    ... be hard to separate our habits from the mechanics of our hearts, which is one important reason ... About Heart Valves • Heart Valve Problems and Causes • Risks, Signs and Symptoms Introduction Understanding Symptoms Recognizing Symptoms ...

  20. Test-state approach to the quantum search problem

    Science.gov (United States)

    Sehrawat, Arun; Nguyen, Le Huy; Englert, Berthold-Georg

    2011-05-01

    The search for “a quantum needle in a quantum haystack” is a metaphor for the problem of finding out which one of a permissible set of unitary mappings—the oracles—is implemented by a given black box. Grover’s algorithm solves this problem with quadratic speedup as compared with the analogous search for “a classical needle in a classical haystack.” Since the outcome of Grover’s algorithm is probabilistic—it gives the correct answer with high probability, not with certainty—the answer requires verification. For this purpose we introduce specific test states, one for each oracle. These test states can also be used to realize “a classical search for the quantum needle” which is deterministic—it always gives a definite answer after a finite number of steps—and 3.41 times as fast as the purely classical search. Since the test-state search and Grover’s algorithm look for the same quantum needle, the average number of oracle queries of the test-state search is the classical benchmark for Grover’s algorithm.

  1. Development of the screening test for hearing problems.

    Science.gov (United States)

    Demorest, Marilyn E; Wark, David J; Erdman, Sue Ann

    2011-12-01

    The goal of this study was to develop a brief self-assessment instrument to screen for communication problems and psychosocial adjustment to hearing impairment as part of a rehabilitative needs assessment. A pseudorandom sample of 1,000 cases was drawn from a large, heterogeneous clinical database containing audiometric data and responses to the Communication Profile for the Hearing Impaired (CPHI; Erdman & Demorest, 1998a). Item response theory was used to derive item-characteristic curves, and item selection was based primarily on item discrimination. Internal consistency, factor structure, sensitivity, and specificity of 2 scales, Communication and Adjustment, were evaluated in a holdout sample of 319 cases from the same database. A 9-item Communication scale and an 11-item Adjustment scale both showed satisfactory internal consistency, and the 20-item test presented a clear 2-factor structure. Sensitivity and specificity functions and positive and negative predictive values indicated that the 2 scales could be used to identify the bottom 2 quartiles of the clinical population, as defined by factor scores on the CPHI. The 2 scales of the Screening Test for Hearing Problems can be used to screen for communication and adjustment problems that warrant a comprehensive rehabilitative assessment.

  2. Testing and Modeling of Contact Problems in Resistance Welding

    DEFF Research Database (Denmark)

    Song, Quanfeng

    together two or three cylindrical parts as well as disc-ring pairs of dissimilar metals. The tests have demonstrated the effectiveness of the model. A theoretical and experimental study is performed on the contact resistance aiming at a more reliable model for numerical simulation of resistance welding...... is validated in some projection welding experiments. The program is also applied to solve some resistance welding operations involving contact problems, showing that numerical simulation facilitates better understand of resistance welding.......As a part of the efforts towards a professional and reliable numerical tool for resistance welding engineers, this Ph.D. project is dedicated to refining the numerical models related to the interface behavior. An FE algorithm for the contact problems in resistance welding has been developed...

  3. Fault Diagnosis of Internal Combustion Engine Valve Clearance Using the Impact Commencement Detection Method.

    Science.gov (United States)

    Jiang, Zhinong; Mao, Zhiwei; Wang, Zijia; Zhang, Jinjie

    2017-12-15

    Internal combustion engines (ICEs) are widely used in many important fields. The valve train clearance of an ICE usually exceeds the normal value due to wear or faulty adjustment. This work aims at diagnosing the valve clearance fault based on the vibration signals measured on the engine cylinder heads. The non-stationarity of the ICE operating condition makes it difficult to obtain the nominal baseline, which is always an awkward problem for fault diagnosis. This paper overcomes the problem by inspecting the timing of valve closing impacts, of which the referenced baseline can be obtained by referencing design parameters rather than extraction during healthy conditions. To accurately detect the timing of valve closing impact from vibration signals, we carry out a new method to detect and extract the commencement of the impacts. The results of experiments conducted on a twelve-cylinder ICE test rig show that the approach is capable of extracting the commencement of valve closing impact accurately and using only one feature can give a superior monitoring of valve clearance. With the help of this technique, the valve clearance fault becomes detectable even without the comparison to the baseline, and the changing trend of the clearance could be trackable.

  4. Fault Diagnosis of Internal Combustion Engine Valve Clearance Using the Impact Commencement Detection Method

    Directory of Open Access Journals (Sweden)

    Zhinong Jiang

    2017-12-01

    Full Text Available Internal combustion engines (ICEs are widely used in many important fields. The valve train clearance of an ICE usually exceeds the normal value due to wear or faulty adjustment. This work aims at diagnosing the valve clearance fault based on the vibration signals measured on the engine cylinder heads. The non-stationarity of the ICE operating condition makes it difficult to obtain the nominal baseline, which is always an awkward problem for fault diagnosis. This paper overcomes the problem by inspecting the timing of valve closing impacts, of which the referenced baseline can be obtained by referencing design parameters rather than extraction during healthy conditions. To accurately detect the timing of valve closing impact from vibration signals, we carry out a new method to detect and extract the commencement of the impacts. The results of experiments conducted on a twelve-cylinder ICE test rig show that the approach is capable of extracting the commencement of valve closing impact accurately and using only one feature can give a superior monitoring of valve clearance. With the help of this technique, the valve clearance fault becomes detectable even without the comparison to the baseline, and the changing trend of the clearance could be trackable.

  5. Butterfly valve. Spjeldventil

    Energy Technology Data Exchange (ETDEWEB)

    Cupedo, D.J.

    1984-02-06

    Butterfly valve comprising a body and a valve seat arranged therein, on which a valve member is supported. The valve member comprises an operating rod and the assembly of valve member and operating rod has a fixed pivot point at the bottom of the body. The operating rod can be moved by means of pins movable in grooves and slots in such a manner that when the valve is opened the valve member first pivots about the pivot point to lift the valve member from the seat and subsequently rotates about the pivot point to fully open the valve. 12 drawings.

  6. 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...

  7. A class of self-similar hydrodynamics test problems

    Energy Technology Data Exchange (ETDEWEB)

    Ramsey, Scott D [Los Alamos National Laboratory; Brown, Lowell S [Los Alamos National Laboratory; Nelson, Eric M [Los Alamos National Laboratory; Alme, Marv L [Los Alamos National Laboratory

    2010-12-08

    We consider self-similar solutions to the gas dynamics equations. One such solution - a spherical geometry Gaussian density profile - has been analyzed in the existing literature, and a connection between it, a linear velocity profile, and a uniform specific internal energy profile has been identified. In this work, we assume the linear velocity profile to construct an entire class of self-similar sol utions in both cylindrical and spherical geometry, of which the Gaussian form is one possible member. After completing the derivation, we present some results in the context of a test problem for compressible flow codes.

  8. A multiple objective test assembly approach for exposure control problems in Computerized Adaptive Testing

    Directory of Open Access Journals (Sweden)

    Theo J.H.M. Eggen

    2010-01-01

    Full Text Available Overexposure and underexposure of items in the bank are serious problems in operational computerized adaptive testing (CAT systems. These exposure problems might result in item compromise, or point at a waste of investments. The exposure control problem can be viewed as a test assembly problem with multiple objectives. Information in the test has to be maximized, item compromise has to be minimized, and pool usage has to be optimized. In this paper, a multiple objectives method is developed to deal with both types of exposure problems. In this method, exposure control parameters based on observed exposure rates are implemented as weights for the information in the item selection procedure. The method does not need time consuming simulation studies, and it can be implemented conditional on ability level. The method is compared with Sympson Hetter method for exposure control, with the Progressive method and with alphastratified testing. The results show that the method is successful in dealing with both kinds of exposure problems.

  9. NASA Work on Fatigue-Induced Cracking of H2 Flow Control Valve Poppet

    Science.gov (United States)

    Maes, Miguel

    2009-01-01

    This slide presentation reviews the work that is being done to resolve a potential problem with the flow control valve poppet that controls the flow of GH2 into the space shuttle's main engine. The STS Hydrogen Flow Control Valve (HFVC) and potential problems that could arise from the failure of a poppet are reviewed. The analysis and testing that were performed are discussed. There is discussion about the current work involved in finding a resolution to the problem, including finding new materials to use in construction of poppetts,

  10. Manufacturable plastic microfluidic valves using thermal actuation.

    Science.gov (United States)

    Pitchaimani, Karthik; Sapp, Brian C; Winter, Adam; Gispanski, Austin; Nishida, Toshikazu; Hugh Fan, Z

    2009-11-07

    A low-cost, manufacturable, thermally actuated, plastic microfluidic valve has been developed. The valve contains an encapsulated, temperature-sensitive fluid, which expands, deflecting a thin elastomeric film into a fluidic channel to control fluid flow. The power input for thermal expansion of each microfluidic valve can be controlled using a printed circuit board (PCB)-based controller, which is suitable for mass production and large-scale integration. A plastic microfluidic device with such valves was fabricated using compression molding and thermal lamination. The operation of the valves was investigated by measuring a change in the microchannel's ionic conduction current mediated by the resistance variation corresponding to the deflection of the microvalve. Valve closing was also confirmed by the disappearance of fluorescence when a fluorescent solution was displaced in the valve region. Valve operation was characterized for heater power ranging from 36 mW to 80 mW. When the valve was actuating, the local channel temperature was 10 to 19 degrees C above the ambient temperature depending on the heater power used. Repetitive valve operations (up to 50 times) have been demonstrated with a flow resulting from a hydrostatic head. Valve operation was tested for a flow rate of 0.33-4.7 microL/min.

  11. Aortic Valve Stenosis

    Science.gov (United States)

    ... rapid, fluttering heartbeat Not eating enough (mainly in children with aortic valve stenosis) Not gaining enough weight (mainly in children with aortic valve stenosis) The heart-weakening effects of aortic valve stenosis ...

  12. 49 CFR 40.267 - What problems always cause an alcohol test to be cancelled?

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false What problems always cause an alcohol test to be... TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Problems in Alcohol Testing § 40.267 What problems... alcohol test if any of the following problems occur. These are “fatal flaws.” You must inform the DER that...

  13. 49 CFR 40.205 - How are drug test problems corrected?

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false How are drug test problems corrected? 40.205... WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Problems in Drug Tests § 40.205 How are drug test problems...), you must try to correct the problem promptly, if doing so is practicable. You may conduct another...

  14. What Is Heart Valve Disease?

    Science.gov (United States)

    ... Heart Valves Sometimes heart valves can’t be repaired and must be replaced. This surgery involves removing the faulty valve and replacing it with a man-made or biological valve. Biological valves are made ...

  15. Effects of dependence in high-dimensional multiple testing problems

    Directory of Open Access Journals (Sweden)

    van de Wiel Mark A

    2008-02-01

    Full Text Available Abstract Background We consider effects of dependence among variables of high-dimensional data in multiple hypothesis testing problems, in particular the False Discovery Rate (FDR control procedures. Recent simulation studies consider only simple correlation structures among variables, which is hardly inspired by real data features. Our aim is to systematically study effects of several network features like sparsity and correlation strength by imposing dependence structures among variables using random correlation matrices. Results We study the robustness against dependence of several FDR procedures that are popular in microarray studies, such as Benjamin-Hochberg FDR, Storey's q-value, SAM and resampling based FDR procedures. False Non-discovery Rates and estimates of the number of null hypotheses are computed from those methods and compared. Our simulation study shows that methods such as SAM and the q-value do not adequately control the FDR to the level claimed under dependence conditions. On the other hand, the adaptive Benjamini-Hochberg procedure seems to be most robust while remaining conservative. Finally, the estimates of the number of true null hypotheses under various dependence conditions are variable. Conclusion We discuss a new method for efficient guided simulation of dependent data, which satisfy imposed network constraints as conditional independence structures. Our simulation set-up allows for a structural study of the effect of dependencies on multiple testing criterions and is useful for testing a potentially new method on π0 or FDR estimation in a dependency context.

  16. Prevention of crack initiation in valve bodies under thermal shock

    Energy Technology Data Exchange (ETDEWEB)

    Delmas, J.; Coppolani, P.

    1996-12-01

    On site and testing experience has shown that cracking in valves affects mainly the stellite hardfacing on seats and discs but may also be a concern for valve bodies. Metallurgical investigations conducted by EDF laboratories on many damaged valves have shown that most of the damage had either a chemical, manufacturing, or operating origin with a strong correlation between the origins and the type of damage. The chemical defects were either excess ferritic dilution of stellite or excess carburizing. Excess carburizing leads to a too brittle hardfacing which cracks under excessive stresses induced on the seating surfaces, via the stem, by too high operating thrusts. The same conditions can also induce cracks of the seats in the presence, in the hardfacing, of hidden defects generated during the welding process. Reduction of the number of defects results first from controls during manufacturing, mainly in the thickness of stellite. On the other hand, maintenance must be fitted to the type of defect. In-situ lapping may lead to release of cobalt, resulting in contamination of the circuit. Furthermore, it is ineffectual in the case of a crack through the seating surface, as is often found on globe valves. The use of new technologies of valves with removable seats and cobalt-free alloys solves permanently this kind of problem.

  17. Estimation and testing problems in auditory neuroscience via clustering.

    Science.gov (United States)

    Hwang, Youngdeok; Wright, Samantha; Hanlon, Bret M

    2017-09-01

    The processing of auditory information in neurons is an important area in neuroscience. We consider statistical analysis for an electrophysiological experiment related to this area. The recorded synaptic current responses from the experiment are observed as clusters, where the number of clusters is related to an important characteristic of the auditory system. This number is difficult to estimate visually because the clusters are blurred by biological variability. Using singular value decomposition and a Gaussian mixture model, we develop an estimator for the number of clusters. Additionally, we provide a method for hypothesis testing and sample size determination in the two-sample problem. We illustrate our approach with both simulated and experimental data. © 2017, The International Biometric Society.

  18. Conical Seat Shut-Off Valve

    Science.gov (United States)

    Farner, Bruce

    2013-01-01

    increased cost, and incurred other reliability issues. With this novel design, the seat is lifted by simply removing the working fluid pressure that presses it against the seat and no external force is required. By eliminating variables associated with existing ball and globe configurations that can have damaging effects upon a valve, this novel design reduces downtime in rocket engine test schedules and maintenance costs.

  19. Numerical study of cavitating flow inside a flush valve

    OpenAIRE

    BAYEUL-LAINE, Annie-Claude; Simonet, Sophie; DUTHEIL, Daniel; Caignaert, Guy

    2011-01-01

    In water supply installations, noise pollution often occurs. As a basic component of a system, a flush valve may frequently be a source of noise and vibration generated by cavitation or high turbulence levels. During valve closing or valve opening, cavitation can be a problem. In order to decrease the noise and to improve the design inside a flush valve, some experimental and numerical analyses were carried out in our laboratories. These analyses led to some improvements in the de...

  20. 46 CFR 61.05-20 - Boiler safety valves.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Boiler safety valves. 61.05-20 Section 61.05-20 Shipping... INSPECTIONS Tests and Inspections of Boilers § 61.05-20 Boiler safety valves. Each safety valve for a drum, superheater, or reheater of a boiler shall be tested at the interval specified by table 61.05-10. ...

  1. 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.

  2. Remote actuated valve implant

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-10

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

  3. Mitral valve regurgitation

    Science.gov (United States)

    ... around the valve. You are at risk for mitral valve regurgitation if you have: Coronary heart disease and high blood pressure Infection of the heart valves Mitral valve prolapse (MVP) Rare conditions, such as untreated syphilis or Marfan ... heart disease. This is a complication of untreated strep throat ...

  4. Tissue engineered aortic valve

    OpenAIRE

    Dohmen, P M

    2012-01-01

    Several prostheses are available to replace degenerative diseased aortic valves with unique advantages and disadvantages. Bioprotheses show excellent hemodynamic behavior and low risk of thromboembolic complications, but are limited by tissue deterioration. Mechanical heart valves have extended durability, but permanent anticoagulation is mandatory. Tissue engineering created a new generation heart valve, which overcome limitations of biological and mechanical heart valves due to remodelling,...

  5. Toward Modeling the Intrinsic Complexity of Test Problems

    Science.gov (United States)

    Shoufan, Abdulhadi

    2017-01-01

    The concept of intrinsic complexity explains why different problems of the same type, tackled by the same problem solver, can require different times to solve and yield solutions of different quality. This paper proposes a general four-step approach that can be used to establish a model for the intrinsic complexity of a problem class in terms of…

  6. 49 CFR 40.271 - How are alcohol testing problems corrected?

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false How are alcohol testing problems corrected? 40.271... WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Problems in Alcohol Testing § 40.271 How are alcohol testing problems corrected? (a) As a BAT or STT, you have the responsibility of trying to complete successfully an...

  7. 49 CFR 40.199 - What problems always cause a drug test to be cancelled?

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false What problems always cause a drug test to be... TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Problems in Drug Tests § 40.199 What problems always cause a drug test to be cancelled? (a) As the MRO, when the laboratory discovers a “fatal flaw” during...

  8. Survey of industrial coal conversion equipment capabilities: valves

    Energy Technology Data Exchange (ETDEWEB)

    Bush, W. A.; Slade, E. C.

    1978-06-01

    A survey of the industrial capabilities of the valve and valve-actuator industry to supply large, high-pressure stop valves for the future coal conversion industry is presented in this report. Also discussed are development and testing capabilities of valve and valve-actuator manufacturers and anticipated lead times required to manufacture advanced design valves for the most stringent service applications. Results indicate that the valve and valve-actuator industry is capable of manufacturing in quantity equipment of the size and for the pressure and temperature ranges which would be required in the coal conversion industry. Valve manufacturers do not, however, have sufficient product application experience to predict the continuing functional ability of valves used for lock-hopper feeders, slurry feeders, and slag-char letdown service. Developmental and testing efforts to modify existing valve designs or to develop new valve concepts for these applications were estimated to range from 1 to 6 years. A testing facility to simulate actuation of critical valves under service conditions would be beneficial.

  9. Current problems regarding abortion, prenatal genetic testing and managing pregnancy

    Directory of Open Access Journals (Sweden)

    Klajn-Tatić Vesna

    2011-01-01

    Full Text Available Current ethical and legal issues with regard to abortion, prenatal genetic testing and managing pregnancy are discussed in this paper. These problems are considered from the legal theory point of view as well as from the standpoint of the Serbian Law, the European Convention for the Protection of Human Rights and Fundamental Freedoms, European Court of Human Rights, legal regulations of several EU countries, the USA, Japan, and their judicial practice. First, the pregnancy termination standards that exist in Serbia are introduced. Then the following issues are explained separately: the pro life and pro choice approaches to abortion; abortion according to the legal approach as a way of survival; the moral and legal status of the fetus; prenatal genetic testing, and finally matters regarding managing pregnancy today. Moral and legal principals of autonomy, namely freedom of choice of the individual, privacy and self-determination give women the right to terminate unwanted pregnancies. In addition, the basic question is whether the right of the woman to abortion clashes with the rights of others. Firstly, with the right of the "fetus to life". Secondly, with the right of the state to intervene in the interest of protecting "the life of the fetus". Third, with the rights of the woman’s partner. The fetus has the moral right to life, but less in relation to the same right of the woman as well as in relation to her right to control her life and her physical and moral integrity. On the other hand, the value of the life of the fetus increases morally and legally with the maturity of gestation; from the third trimester, the interest of the state prevails in the protection of the "life of the fetus" except when the life or health of the pregnant woman are at risk. As regards the rights of the woman’s partner, namely the husband’s opinion, there is no legal significance. The law does not request his participation in the decision on abortion because

  10. Development of cyclonic valves; Desenvolvimento de valvulas ciclonicas

    Energy Technology Data Exchange (ETDEWEB)

    Moraes, Carlos Alberto Capela; Marins, Luiz Philipe Martinez; Monteiro, Andre Sampaio; Silva, Fabricio Soares da [Centro de Pesquisas da Petrobras (CENPES). Gerencia de Tecnologia de Processamento e Avaliacao de Petroleo (Brazil)], e-mails: capela@petrobras.com.br, philipe@petrobras.com.br, asmonteiro@petrobras.com.br, fabriciosoares@petrobras.com.br; Souza, Marcos Aurelio de

    2009-06-15

    This study proposes a possible solution for one of the most severe problems encountered in primary oil-water separation - the formation of stable emulsions. This is largely due to the action of the conventional valves used in the production process and in primary processing activities. Choke and control valves, widely used devices in a production plant, are designed to inflict a significant pressure drop on a fluid stream to control process variables (flow-rate, liquid levels etc.). However, despite facilitating the production plant controllability, these pressure drops can cause deleterious effects on the primary processing activities, mainly on phase separation. Multiphase (oil + water or even gas + oil + water) streams are severely disturbed by the punctual high rate of turbulent energy dissipation due to the passage of the multiphase stream through the valve openings. The high turbulence level acts as a dispersion tool causing the formation of very severe oil in water and water in oil emulsions. This study describes a R and D project based on a new concept for a low shearing valve capable of imposing the required pressure drop on a multiphase process stream without creating emulsions and, in fact, helping to separate the distinct stream phases. PETROBRAS has protected the intellectual proprietary rights of this concept with registered patents. The conceptual design was further developed in a set of mechanical designs and prototypes. These were successfully tested by comparing their performance in terms of pressure drop characteristics and emulsion generation with those of conventional control valves. The concept and equipment have been completely proved and the next project stage will include the optimization of the valve geometry and contacting an equipment maker to study industrial production and commercialization. (author)

  11. Fracturing a dysfunctional Edwards Perimount bioprosthetic valve to facilitate percutaneous valve-in-valve placement of SAPIEN 3 valve with modified delivery system.

    Science.gov (United States)

    Shahanavaz, Shabana; Rockefeller, Toby; Nicolas, Ramzi; Balzer, David

    2017-10-10

    Pulmonary valve replacement via surgical implantation of a bioprosthetic valve (BPV) is a well-established treatment for patients with dysfunctional RV outflow tracts. BPVs are prone to structural deterioration, and will eventually require replacement. Recently, percutaneous valve-in-valve (VIV) placement of transcatheter valves has established itself as a safe and effective alternative to surgical revision. Unfortunately, VIV therapy is inherently limited by the inner diameter of the BPV, which restricts the number of eligible patients. Other centers have reported on the feasibility of cracking certain BPVs with ultra high-pressure balloons in bench testing. We now report cracking an Edwards Perimount BPV in the pulmonary position to facilitate VIV placement of an Edwards SAPIEN 3. The ability to crack the Perimount valve allowed placement of a larger valve than previously considered and minimized the final valve gradient. In an effort to avoid the morbidity and mortality of surgical pulmonary valve replacement, this new strategy will expand the number of patients eligible for percutaneous VIV therapy. © 2017 Wiley Periodicals, Inc.

  12. Multidisciplinary optimization of a butterfly valve.

    Science.gov (United States)

    Song, Xue Guan; Wang, Lin; Baek, Seok Heum; Park, Young Chul

    2009-07-01

    A butterfly valve is a type of flow control device, typically used to regulate fluid flow. This paper proposes a new process to meet desired needs in valve design that is characterized by the complex configuration. First, the need is identified according to the valve user/company, and then the problem is defined with a characteristic function. Second, the initial model of valve is made, and then the initial analysis including fluid and/or structural analysis is carried out to predict the fluid and/or structural performance of the valve. Third, the optimization in the form of mathematical functions, which considers single or multiple objective and/or discipline, is handled. This part includes the design of computer experiment, approximation technique, topology optimization and sizing optimization. Finally, the validation experiment is conducted based on the optimum result to verify the accuracy of the optimization. An example is provided to confirm the availability of the process proposed here.

  13. Living with Heart Valve Disease

    Science.gov (United States)

    ... as well as surgery for adults who have aortic valve stenosis. Doctors often use balloon valvuloplasty to repair valve stenosis in infants and children. Replacing Heart Valves Sometimes heart valves can’t ...

  14. What Causes Heart Valve Disease?

    Science.gov (United States)

    ... as well as surgery for adults who have aortic valve stenosis. Doctors often use balloon valvuloplasty to repair valve stenosis in infants and children. Replacing Heart Valves Sometimes heart valves can’t ...

  15. The botulinum neurotoxin LD50 test - problems and solutions

    National Research Council Canada - National Science Library

    Bitz, Silke

    2010-01-01

    ... on cosmetic testing in animals in the case of Botulinum Neurotoxin (BoNT) testing. The European Pharmacopoeia monograph allows for the use of three alternative methods provided they are validated...

  16. Social problems of indeterminate and false positive HIV test results ...

    African Journals Online (AJOL)

    Increased availability of Human Immunodeficiency Virus (HIV) screening test and more public enlightenment have resulted in more people coming forward to access counseling and testing at the HIV counseling and testing centers in Nigeria. Some of the clients however obtained indeterminate and false positive results ...

  17. Valved stent for off-pump mitral valve replacement

    OpenAIRE

    Ma, L.(School of Physics, Shandong University, Shandong, China)

    2004-01-01

    Résumé Objectif : Evaluer un remplacement de valve mitrale hors-pompe avec des stents valvés Méthode: Des homografts préservés dans du glutaraldehyde ont été suturés dans une prothèse tubulaire avant d'être soudés à deux stents Z en nitinol pour créer deux couronnes auto- extensibles. A) Nous avons testé la valve in vitro en utilisant un circuit pulsatile fermé (mock loop) ayant de débuter les expériences sur les porcs. (n=8, 46 .0± 4.3 kg : B). L'oreillette gauche a été exposée p...

  18. Valve-in-valve outcome: design impact of a pre-existing bioprosthesis on the hydrodynamics of an Edwards Sapien XT valve.

    Science.gov (United States)

    Doose, Christian; Kütting, Maximilian; Egron, Sandrine; Farhadi Ghalati, Pejman; Schmitz, Christoph; Utzenrath, Marc; Sedaghat, Alexander; Fujita, Buntaro; Schmitz-Rode, Thomas; Ensminger, Stephan; Steinseifer, Ulrich

    2017-03-01

    Bioprosthetic aortic heart valves are increasingly implanted in younger patients. Therefore, a strategy for potential valve failure should be developed before implanting the 'first valve'. The goal of this in vitro study was to provide insight into the effects of the design of a bioprosthesis on a valve-in-valve implanted Sapien XT valve. The hydrodynamic performance of a 23-mm Sapien XT valve implanted in Vascutek Aspire, Edwards Perimount, Medtronic Mosaic and St. Jude Medical Trifecta heart valves was investigated in a left heart simulator. In addition to the hydrodynamic results, the leaflet dynamics were analysed in high-speed video recordings of the tests. All valve-in-valve combinations in this study fulfilled the minimum acceptance criteria defined by relevant approval standards (e.g. ISO 5840) but displayed significant differences in their performances. Small inner diameters of the bioprostheses were associated with increased mean pressure gradients, decreased effective orifice areas and geometric opening areas as well as with pin-wheeling and uneven leaflet motion. In addition, implantation in bioprostheses with internally mounted leaflets was associated with lower paravalvular leakage. The results of this study suggest that a surgical bioprosthesis with a large inner diameter and internally mounted leaflets improves the heamodynamics and potentially the durability of a valve-in-valve combination. These results should give the attending physicians critical information to consider when deciding on a bioprosthesis for younger patients.

  19. Mitral valve prolapse

    Science.gov (United States)

    ... mitral valve prolapse is called "mitral valve prolapse syndrome," and includes: Chest pain (not caused by coronary artery disease or a heart attack) Dizziness Fatigue Panic attacks Sensation of feeling the heart beat ( palpitations ) ...

  20. Mitral Valve Stenosis

    Science.gov (United States)

    ... valve stenosis include: Rheumatic fever. A complication of strep throat, rheumatic fever can damage the mitral valve. Rheumatic ... children see your doctor for sore throats. Untreated strep throat infections can develop into rheumatic fever. Fortunately, strep ...

  1. Multi-Dimensional, Non-Pyrolyzing Ablation Test Problems

    Science.gov (United States)

    Risch, Tim; Kostyk, Chris

    2016-01-01

    Non-pyrolyzingcarbonaceous materials represent a class of candidate material for hypersonic vehicle components providing both structural and thermal protection system capabilities. Two problems relevant to this technology are presented. The first considers the one-dimensional ablation of a carbon material subject to convective heating. The second considers two-dimensional conduction in a rectangular block subject to radiative heating. Surface thermochemistry for both problems includes finite-rate surface kinetics at low temperatures, diffusion limited ablation at intermediate temperatures, and vaporization at high temperatures. The first problem requires the solution of both the steady-state thermal profile with respect to the ablating surface and the transient thermal history for a one-dimensional ablating planar slab with temperature-dependent material properties. The slab front face is convectively heated and also reradiates to a room temperature environment. The back face is adiabatic. The steady-state temperature profile and steady-state mass loss rate should be predicted. Time-dependent front and back face temperature, surface recession and recession rate along with the final temperature profile should be predicted for the time-dependent solution. The second problem requires the solution for the transient temperature history for an ablating, two-dimensional rectangular solid with anisotropic, temperature-dependent thermal properties. The front face is radiatively heated, convectively cooled, and also reradiates to a room temperature environment. The back face and sidewalls are adiabatic. The solution should include the following 9 items: final surface recession profile, time-dependent temperature history of both the front face and back face at both the centerline and sidewall, as well as the time-dependent surface recession and recession rate on the front face at both the centerline and sidewall. The results of the problems from all submitters will be

  2. Modal data for the BARC challenge problem Test Report

    Energy Technology Data Exchange (ETDEWEB)

    Rohe, Daniel Peter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2018-01-22

    Modal testing was performed on the uncut BARC structure as a whole and broken into its two sub-assemblies. The structure was placed on soft foam during the test. Excitation was provided with a small modal hammer attached to an actuator. Responses were measured using a 3D Scanning Laser Doppler Vibrometer. Data, shapes, and geometry from this test can be downloaded in Universal File Format from the Sandia Connect SharePoint site.

  3. Isolated Pulmonary Valve Endocarditis

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Hatamizadeh

    2009-06-01

    Full Text Available Infective endocarditis is one of the most severe complications of parenteral drug abuse. The outstanding clinical feature of infective endocarditis in intravenous drug abusers is the high incidence of right-sided valve infection, and the tricuspid valve is involved in 60% to 70% of the cases. We herein report a case of isolated pulmonic valve infective endocarditis with a native pulmonary valve.

  4. A case of SAPIEN XT valve fallen into left ventricle during valve-in-valve transcatheter aortic valve implantation.

    Science.gov (United States)

    Koizumi, Shigeki; Ehara, Natsuhiko; Nishiya, Kenta; Koyama, Tadaaki

    2017-06-24

    Late transcatheter heart valve embolization is a rare but life-threatening complication of transcatheter aortic valve implantation. Surgical intervention is performed for most cases, but some cases were treated by valve-in-valve transcatheter aortic valve implantation. We describe a patient in whom a 29-mm Edwards SAPIEN XT valve migrated into the left ventricular outflow tract 41 days after the initial implantation. We tried to perform valve-in-valve transcatheter aortic valve implantation using a transfemoral approach. As soon as the second transcatheter heart valve touched the first implanted valve, it fell into the left ventricle. Immediate surgical intervention was required. The first valve was removed, and surgical aortic valve replacement was successfully performed. In conclusion, we should choose surgical aortic valve replacement for late transcatheter heart valve embolization. Even if we need to treat by catheter intervention, transapical approach may be better.

  5. Assessment of slurry pressure letdown valve and slurry block valve technology for direct coal liquefaction demonstration and pioneer commercial plants

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, R.P.

    1984-10-01

    This report examines the status of the technology of high pressure slurry letdown valves and slurry block valves in coal liquefaction service. All of the demonstration and pioneer commercial direct liquefaction plant designs call for the use of high pressure slurry letdown valves for flow control and slurry block valves for flow isolation. Successful performance and reliability of these valves is a serious concern because of the severity of the process streams and the limited experience and performance data on these valves under such conditions. The objectives of this report are: (1) to examine the existing data base on these valves from the four major direct coal liquefaction pilot plants in the US, (2) to present the recommendations from the pilot plant experience, (3) to examine the specifications for the letdown and block valves in the demonstration/pioneer commercial designs, and (4) to identify the scale-up issues, data gaps, and development and testing needs. 23 references, 20 figures, 7 tables.

  6. Multiple testing in orthopedic literature: a common problem?

    NARCIS (Netherlands)

    Walenkamp, Monique M. J.; Roes, Kit C. B.; Bhandari, Mohit; Goslings, J. Carel; Schep, Niels W. L.

    2013-01-01

    Performing multiple tests in primary research is a frequent subject of discussion. This discussion originates from the fact that when multiple tests are performed, it becomes more likely to reject one of the null hypotheses, conditional on that these hypotheses are true and thus commit a type one

  7. The botulinum neurotoxin LD50 test - problems and solutions.

    Science.gov (United States)

    Bitz, Silke

    2010-01-01

    Apart from the fact that the LD50 test is generally considered a procedure causing severe distress, which alone should result in its immediate deletion, it also conflicts with the EU wide ban on cosmetic testing in animals in the case of Botulinum Neurotoxin (BoNT) testing. The European Pharmacopoeia monograph allows for the use of three alternative methods provided they are validated. However these alternative assays are neither implemented by the manufactures of BoNT products nor are they enforced by the responsible authorities, e.g. by deleting the LD50 from the European Pharmacopoeia. The number of animals used for the testing of BoNT is not officially recorded. However, data from an undercover investigation allow the estimation that the number of mice used in LD50tests for BoNT products is greater than 600,000 per year worldwide.

  8. 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 ...

  9. Indentation hardness: A simple test that correlates with the dissipated-energy predictor for fatigue-life in bovine pericardium membranes for bioprosthetic heart valves.

    Science.gov (United States)

    Tobaruela, Almudena; Rojo, Francisco Javier; García Paez, José María; Bourges, Jean Yves; Herrero, Eduardo Jorge; Millán, Isabel; Alvarez, Lourdes; Cordon, Ángeles; Guinea, Gustavo V

    2016-08-01

    The aim of this study was to evaluate the variation of hardness with fatigue in calf pericardium, a biomaterial commonly used in bioprosthetic heart valves, and its relationship with the energy dissipated during the first fatigue cycle that has been shown to be a predictor of fatigue-life (García Páez et al., 2006, 2007; Rojo et al., 2010). Fatigue tests were performed in vitro on 24 pericardium specimens cut in a root-to-apex direction. The specimens were subjected to a maximum stress of 1MPa in blocks of 10, 25, 50, 100, 250, 500, 1000 and 1500 cycles. By means of a modified Shore A hardness test procedure, the hardness of the specimen was measured before and after fatigue tests. Results showed a significant correlation of such hardness with fatigue performance and with the energy dissipated in the first cycle of fatigue, a predictor of pericardium durability. The study showed indentation hardness as a simple and reliable indicator of mechanical performance, one which could be easily implemented in improving tissue selection. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Light phase testing of social behaviors: not a problem

    Directory of Open Access Journals (Sweden)

    Mu Yang

    2008-12-01

    Full Text Available The rich repertoire of mouse social behaviors makes it possible to use mouse models to study neurodevelopmental disorders characterized by social deficits. The fact that mice are naturally nocturnal animals raises a critical question of whether behavioral experiments should be strictly conducted in the dark phase and whether light phase testing is a major methodologically mistake. Although mouse social tasks have been performed in both phases in different laboratories, there seems to be no general consensus on whether testing phase is a critical factor or not. A recent study from our group showed remarkably similar social scores obtained from inbred mice tested in the light and the dark phase, providing evidence that light phase testing could yield reliable results as robust as dark phase testing for the sociability test. Here we offer a comprehensive review on mouse social behaviors measured in light and dark phases and explain why it is reasonable to test laboratory mice in experimental social tasks in the light phase.

  11. Pulmonary heart valve replacement using stabilized acellular xenogeneic scaffolds; effects of seeding with autologous stem cells

    Directory of Open Access Journals (Sweden)

    Harpa Marius Mihai

    2015-12-01

    Full Text Available Background: We hypothesized that an ideal heart valve replacement would be acellular valve root scaffolds seeded with autologous stem cells. To test this hypothesis, we prepared porcine acellular pulmonary valves, seeded them with autologous adipose derived stem cells (ADSCs and implanted them in sheep and compared them to acellular valves.

  12. The Leipzig experience with robotic valve surgery.

    Science.gov (United States)

    Autschbach, R; Onnasch, J F; Falk, V; Walther, T; Krüger, M; Schilling, L O; Mohr, F W

    2000-01-01

    The study describes the single-center experience using robot-assisted videoscopic mitral valve surgery and the early results with a remote telemanipulator-assisted approach for mitral valve repair. Out of a series of 230 patients who underwent minimally invasive mitral valve surgery, in 167 patients surgery was performed with the use of robotic assistance. A voice-controlled robotic arm was used for videoscopic guidance in 152 cases. Most recently, a computer-enhanced telemanipulator was used in 15 patients to perform the operation remotely. The mitral valve was repaired in 117 and replaced in all other patients. The voice-controlled robotic arm (AESOP 3000) facilitated videoscopic-assisted mitral valve surgery. The procedure was completed without the need for an additional assistant as "solo surgery." Additional procedures like radiofrequency ablation and tricuspid valve repair were performed in 21 and 4 patients, respectively. Duration of bypass and clamp time was comparable to conventional procedures (107 A 34 and 50 A 16 min, respectively). Hospital mortality was 1.2%. Using the da Vinci telemanipulation system, remote mitral valve repair was successfully performed in 13 of 15 patients. Robotic-assisted less invasive mitral valve surgery has evolved to a reliable technique with reproducible results for primary operations and for reoperations. Robotic assistance has enabled a solo surgery approach. The combination with radiofrequency ablation (Mini Maze) in patients with chronic atrial fibrillation has proven to be beneficial. The use of telemanipulation systems for remote mitral valve surgery is promising, but a number of problems have to be solved before the introduction of a closed chest mitral valve procedure.

  13. Crash test for the Copenhagen problem with oblateness

    Science.gov (United States)

    Zotos, Euaggelos E.

    2015-05-01

    The case of the planar circular restricted three-body problem where one of the two primaries is an oblate spheroid is investigated. We conduct a thorough numerical analysis on the phase space mixing by classifying initial conditions of orbits and distinguishing between three types of motion: (i) bounded, (ii) escape and (iii) collisional. The presented outcomes reveal the high complexity of this dynamical system. Furthermore, our numerical analysis shows a strong dependence of the properties of the considered escape basins with the total orbital energy, with a remarkable presence of fractal basin boundaries along all the escape regimes. Interpreting the collisional motion as leaking in the phase space we related our results to both chaotic scattering and the theory of leaking Hamiltonian systems. We also determined the escape and collisional basins and computed the corresponding escape/crash times. The highly fractal basin boundaries observed are related with high sensitivity to initial conditions thus implying an uncertainty between escape solutions which evolve to different regions of the phase space. We hope our contribution to be useful for a further understanding of the escape and crash mechanism of orbits in this version of the restricted three-body problem.

  14. Development of a system for monitoring and diagnosis using Fuzzy logic in control valves of laboratory test equipment of Experimental Center Aramar; Desenvolvimento de um sistema de monitoracao e diagnostico utilizando logica Fuzzy aplicado a valvulas de controle de processo do CEA - Centro Experimental Aramar

    Energy Technology Data Exchange (ETDEWEB)

    Porto Junior, Almir Carlos Soares

    2014-07-01

    The question of components reliability, specifically process control valves, has become an important issue to be investigated in nuclear power plants and other areas such as refinery or offshore oil rig, considering the safety and life extension of the plant. The development of non intrusive monitoring and diagnostic method allows the identification of defects in components of the plant during normal operation. The objective of this dissertation is to present an analysis and diagnosis of control valves of a steam plant part that simulates the secondary circuit of a pressurized water reactor. This installation is part of propulsion equipment testing laboratory of the Brazilian Navy, at Ipero-SP. The methodology for design is based on graphical analysis of two parameters, the valve air pressure actuator and the displacement of the valve plug. These data are extracted by a smart positioner, part of Delta V™ Automation System. An analysis is implemented in detecting anomalies by an approach using Expert Systems by the technique of fuzzy logic. Once the basic measures of control valves are taken, it is possible to detect symptoms of failure, leakage, friction, damage, etc. The monitoring and diagnostic system has been designed in MATLAB® version 2009{sup th} by the complement 'Fuzzy Logic Toolbox'. It is a noninvasive technique. Thus, it is possible to know what is happening with the chosen components, just analyzing the parameters of the valve. The software called ValveLink® (developed by Emerson) receives signals from hardware component (intelligent positioner) installed next to the control valve. These signals (electrical current) are transformed into information which are used input parameters: air pressure valve actuator and valve plug displacement. With the use of fuzzy logic, these parameters are interpreted. They suffer inferences by rules written by experts in valves. After these inferences, the information is processed and sent as output signals

  15. Low-Mass VOST Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Two low-mass, linear throttling, high-efficiency, leak-proof cryogenic valves of diameters 1/2" and 4" will be built and tested. Based upon cryogenically-proven...

  16. VOST Flow-Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Two cryogenic flow-control valves of diameters 1/2" and 2" will be built and tested. Based on cryogenically-proven Venturi Off-Set Technology (VOST) they have no...

  17. A Hybrid Tissue-Engineered Heart Valve

    National Research Council Canada - National Science Library

    Alavi, S Hamed; Kheradvar, Arash

    2015-01-01

    This study describes the efforts to develop and test the first hybrid tissue-engineered heart valve whose leaflets are composed of an extra-thin superelastic Nitinol mesh tightly enclosed by uniform...

  18. Main Oxidizer Valve Design

    Science.gov (United States)

    Addona, Brad; Eddleman, David

    2015-01-01

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

  19. Problem-Solving Test: Expression Cloning of the Erythropoietin Receptor

    Science.gov (United States)

    Szeberenyi, Jozsef

    2008-01-01

    Terms to be familiar with before you start to solve the test: cytokines, cytokine receptors, cDNA library, cDNA synthesis, poly(A)[superscript +] RNA, primer, template, reverse transcriptase, restriction endonucleases, cohesive ends, expression vector, promoter, Shine-Dalgarno sequence, poly(A) signal, DNA helicase, DNA ligase, topoisomerases,…

  20. Problem-Solving Test: Submitochondrial Localization of Proteins

    Science.gov (United States)

    Szeberenyi, Jozsef

    2011-01-01

    Mitochondria are surrounded by two membranes (outer and inner mitochondrial membrane) that separate two mitochondrial compartments (intermembrane space and matrix). Hundreds of proteins are distributed among these submitochondrial components. A simple biochemical/immunological procedure is described in this test to determine the localization of…

  1. Development and Implementation of Radiation-Hydrodynamics Verification Test Problems

    Energy Technology Data Exchange (ETDEWEB)

    Marcath, Matthew J. [Los Alamos National Laboratory; Wang, Matthew Y. [Los Alamos National Laboratory; Ramsey, Scott D. [Los Alamos National Laboratory

    2012-08-22

    Analytic solutions to the radiation-hydrodynamic equations are useful for verifying any large-scale numerical simulation software that solves the same set of equations. The one-dimensional, spherically symmetric Coggeshall No.9 and No.11 analytic solutions, cell-averaged over a uniform-grid have been developed to analyze the corresponding solutions from the Los Alamos National Laboratory Eulerian Applications Project radiation-hydrodynamics code xRAGE. These Coggeshall solutions have been shown to be independent of heat conduction, providing a unique opportunity for comparison with xRAGE solutions with and without the heat conduction module. Solution convergence was analyzed based on radial step size. Since no shocks are involved in either problem and the solutions are smooth, second-order convergence was expected for both cases. The global L1 errors were used to estimate the convergence rates with and without the heat conduction module implemented.

  2. 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).

  3. Transcatheter aortic valve implantation with balloonexpandable valve: early experience from China

    Directory of Open Access Journals (Sweden)

    Qingsheng Lu

    2015-08-01

    Full Text Available Abstract Objective: The aim of the current study was to evaluate the early experience of the application of transcatheter aortic valve implantation with the balloon-expandable system in China. The transcatheter aortic valve implantation technology has been widely used for patients with inoperable severe aortic stenosis in the developed world. The application of transcatheter aortic valve implantation is still in the early stages of testing in China, particularly for the balloon-expandable valve procedure. Methods: This was a retrospective study. All patients undergoing transcatheter aortic valve implantation with balloon-expandable system in our hospital between 2011 and 2014 were included. Edwards SAPIEN XT Transcatheter Heart Valve was used. The improvement of valve and heart function was evaluated as well as 30-day mortality and major complications according to the VARC-2 definition. Results: A total of 10 transcatheter aortic valve implantation procedures with the balloon-expandable system were performed in our hospital, of which 9 were transfemoral and 1 was transapical. The median age was 76 years, and the median STS score and Logistic EuroSCORE (% were 8.9 and 16.2. The implantation was successfully conducted in all patients, only 2 patients had mild paravalvular leak. There was no second valve implantation. Moreover, no 30-day mortality or complications was reported. Following the transcatheter aortic valve implantation procedure, the heart and valve functions had improved significantly. During the follow-up period of 3-34 months, one patient died of lung cancer 13 months after the operation. Conclusion: This early experience has provided preliminary evidence for the safety and efficacy of transcatheter aortic valve implantation procedure with the balloon-expandable system in the developing world with an increasing aging population.

  4. In vitro evaluation of the iValve: a novel hands-free speech valve.

    Science.gov (United States)

    van der Houwen, Eduard B; van Kalkeren, Tjouwke A; Burgerhof, Johannes G M; van der Laan, Bernard F A M; Verkerke, Gijsbertus J

    2011-12-01

    We performed in vitro evaluation of a novel, disposable, automatic hands-free tracheostoma speech valve for laryngectomy patients based upon the principle of inhalation. The commercially available automatic speech valves close upon strong exhalation and open again when the pressure drops. This method makes long sentences or pauses difficult. The novel iValve is designed to allow almost natural speech, with mid-sentence pausing and whispering. The inhalation closing flows and exhalation opening pressures of 6 iValve prototype versions at different settings were compared with physiological values. The airflow resistance at inhalation was compared to physiological values and to commercial valve values. The iValve prototypes showed flow and pressure ranges in concordance with the physiological values in the literature. The airflow resistance in the breathing mode was within the physiological airflow resistance range, yet above the values from the two commercial valves. The resistance in the speaking mode was above the physiological airflow resistance range. In vitro tests show that the iValve versions can be selected and adjusted to operate within the physiological range. The airflow resistance in the breathing mode is good. In speaking mode, inhalation should, and can, be decreased. The iValve should offer the patient a more intuitively useable alternative with more dynamic speech. Its low cost allows disposability and wider use.

  5. The efficient market hypothesis: problems with interpretations of empirical tests

    Directory of Open Access Journals (Sweden)

    Denis Alajbeg

    2012-03-01

    Full Text Available Despite many “refutations” in empirical tests, the efficient market hypothesis (EMH remains the central concept of financial economics. The EMH’s resistance to the results of empirical testing emerges from the fact that the EMH is not a falsifiable theory. Its axiomatic definition shows how asset prices would behave under assumed conditions. Testing for this price behavior does not make much sense as the conditions in the financial markets are much more complex than the simplified conditions of perfect competition, zero transaction costs and free information used in the formulation of the EMH. Some recent developments within the tradition of the adaptive market hypothesis are promising regarding development of a falsifiable theory of price formation in financial markets, but are far from giving assurance that we are approaching a new formulation. The most that can be done in the meantime is to be very cautious while interpreting the empirical evidence that is presented as “testing” the EMH.

  6. Test Problems for Large-Scale Multiobjective and Many-Objective Optimization.

    Science.gov (United States)

    Cheng, Ran; Jin, Yaochu; Olhofer, Markus; Sendhoff, Bernhard

    2017-12-01

    The interests in multiobjective and many-objective optimization have been rapidly increasing in the evolutionary computation community. However, most studies on multiobjective and many-objective optimization are limited to small-scale problems, despite the fact that many real-world multiobjective and many-objective optimization problems may involve a large number of decision variables. As has been evident in the history of evolutionary optimization, the development of evolutionary algorithms (EAs) for solving a particular type of optimization problems has undergone a co-evolution with the development of test problems. To promote the research on large-scale multiobjective and many-objective optimization, we propose a set of generic test problems based on design principles widely used in the literature of multiobjective and many-objective optimization. In order for the test problems to be able to reflect challenges in real-world applications, we consider mixed separability between decision variables and nonuniform correlation between decision variables and objective functions. To assess the proposed test problems, six representative evolutionary multiobjective and many-objective EAs are tested on the proposed test problems. Our empirical results indicate that although the compared algorithms exhibit slightly different capabilities in dealing with the challenges in the test problems, none of them are able to efficiently solve these optimization problems, calling for the need for developing new EAs dedicated to large-scale multiobjective and many-objective optimization.

  7. Externally heated valve engine a new approach to piston engines

    CERN Document Server

    Kazimierski, Zbyszko

    2016-01-01

    This book reports on a novel approach for generating mechanical energy from different, external heat sources using the body of a typical piston engine with valves. By presenting simple yet effective numerical models, the authors show how this new approach, which combines existing internal combustion technology with a lubrication system, is able to offer an economic solution to the problem of mechanical energy generation in piston engines. Their results also show that a stable heat generation process can be guaranteed outside of the engine. The book offers a detailed report on physical and numerical models of 4-stroke and 2-stroke versions of the EHVE together with different models of heat exchange, valves and results of their simulations. It also delivers the test results of an engine prototype run in laboratory conditions. By presenting a novel theoretical framework and providing readers with extensive knowledge of both the advantages and challenges of the method, this book is expected to inspire academic re...

  8. Another baryon miracle? Testing solutions to the "missing dwarfs" problem

    Science.gov (United States)

    Trujillo-Gomez, Sebastian; Schneider, Aurel; Papastergis, Emmanouil; Reed, Darren S.; Lake, George

    2018-01-01

    The dearth of dwarf galaxies in the local universe is hard to reconcile with the large number of low mass haloes expected within the concordance ΛCDM paradigm. In this paper we perform a systematic evaluation of the uncertainties affecting the measurement of dark matter (DM) halo abundance using galaxy kinematics. Using a large sample of dwarf galaxies with spatially-resolved kinematics we derive a correction to obtain the abundance of galaxies as a function of maximum circular velocity -a direct probe of halo mass- from the line-of-sight velocity function in the Local Volume. This method provides a direct means of comparing the predictions of theoretical models and simulations (including nonstandard cosmologies and novel galaxy formation physics) to the observational constraints. The new "galactic Vmax" function is steeper than the line-of-sight velocity function but still shallower than the theoretical CDM expectation, implying that unaccounted baryonic physics may be necessary to reduce the predicted abundance of galaxies. Using the galactic Vmax function we investigate the theoretical effects of feedback-powered outflows and photoevaporation of gas due to reionisation. At the 3-σ confidence level we find that feedback and reionisation are not effective enough to reconcile the disagreement. In the case of maximum baryonic effects, the theoretical prediction still deviates significantly from the observations for Vmax < 60 km s-1. CDM predicts at least 1.8 times more galaxies with Vmax = 50 km -1 and 2.5 times more than observed at 30 km s -1. Recent hydrodynamic simulations seem to resolve the discrepancy but disagree with the properties of observed galaxies with spatially-resolved kinematics. This abundance problem might point to the need to modify cosmological predictions at small scales.

  9. A collection of test problems for ordinary differential equation solvers which have provisions for rootfinding

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, S.

    1987-08-01

    Several popular ordinary differential equation (ode) solvers contain provisions for locating roots of functions which depend on the solution of the ode. A collection of problems for testing such solvers is described in this report. In addition to several well-known problems, the collection contains other interesting problems which have not previously appeared in the literature.

  10. Sex Differences and Self-Reported Attention Problems During Baseline Concussion Testing.

    Science.gov (United States)

    Brooks, Brian L; Iverson, Grant L; Atkins, Joseph E; Zafonte, Ross; Berkner, Paul D

    2016-01-01

    Amateur athletic programs often use computerized cognitive testing as part of their concussion management programs. There is evidence that athletes with preexisting attention problems will have worse cognitive performance and more symptoms at baseline testing. The purpose of this study was to examine whether attention problems affect assessments differently for male and female athletes. Participants were drawn from a database that included 6,840 adolescents from Maine who completed Immediate Postconcussion Assessment and Cognitive Testing (ImPACT) at baseline (primary outcome measure). The final sample included 249 boys and 100 girls with self-reported attention problems. Each participant was individually matched for sex, age, number of past concussions, and sport to a control participant (249 boys, 100 girls). Boys with attention problems had worse reaction time than boys without attention problems. Girls with attention problems had worse visual-motor speed than girls without attention problems. Boys with attention problems reported more total symptoms, including more cognitive-sensory and sleep-arousal symptoms, compared with boys without attention problems. Girls with attention problems reported more cognitive-sensory, sleep-arousal, and affective symptoms than girls without attention problems. When considering the assessment, management, and outcome from concussions in adolescent athletes, it is important to consider both sex and preinjury attention problems regarding cognitive test results and symptom reporting.

  11. Assessing corrosion problems in photovoltaic cells via electrochemical stress testing

    Science.gov (United States)

    Shalaby, H.

    1985-01-01

    A series of accelerated electrochemical experiments to study the degradation properties of polyvinylbutyral-encapsulated silicon solar cells has been carried out. The cells' electrical performance with silk screen-silver and nickel-solder contacts was evaluated. The degradation mechanism was shown to be electrochemical corrosion of the cell contacts; metallization elements migrate into the encapsulating material, which acts as an ionic conducting medium. The corrosion products form a conductive path which results in a gradual loss of the insulation characteristics of the encapsulant. The precipitation of corrosion products in the encapsulant also contributes to its discoloration which in turn leads to a reduction in its transparency and the consequent optical loss. Delamination of the encapsulating layers could be attributed to electrochemical gas evolution reactions. The usefulness of the testing technique in qualitatively establishing a reliability difference between metallizations and antireflection coating types is demonstrated.

  12. (Non)existence of polynomial kernels for the Test Cover problem

    DEFF Research Database (Denmark)

    Gutin, G.; Muciaccia, G.; Yeo, A.

    2013-01-01

    The input of the Test Cover problem consists of a set V of vertices, and a collection E={E1,.,Em} of distinct subsets of V, called tests. A test Eq separates a pair vi,vj of vertices if |{vi,vj}â̂©Eq|=1. A subcollection T⊆E is a test cover if each pair vi,vj of distinct vertices is separated...... by a test in T. The objective is to find a test cover of minimum cardinality, if one exists. This problem is NP-hard. We consider two parameterizations of the Test Cover problem with parameter k: (a) decide whether there is a test cover with at most k tests, (b) decide whether there is a test cover...

  13. Medical Physics: Forming and testing solutions to clinical problems.

    Science.gov (United States)

    Tsapaki, Virginia; Bayford, Richard

    2015-11-01

    According to the European Federation of Organizations for Medical Physics (EFOMP) policy statement No. 13, "The rapid advance in the use of highly sophisticated equipment and procedures in the medical field increasingly depends on information and communication technology. In spite of the fact that the safety and quality of such technology is vigorously tested before it is placed on the market, it often turns out that the safety and quality is not sufficient when used under hospital working conditions. To improve safety and quality for patient and users, additional safeguards and related monitoring, as well as measures to enhance quality, are required. Furthermore a large number of accidents and incidents happen every year in hospitals and as a consequence a number of patients die or are injured. Medical Physicists are well positioned to contribute towards preventing these kinds of events". The newest developments related to this increasingly important medical speciality were presented during the 8th European Conference of Medical Physics 2014 which was held in Athens, 11-13 September 2014 and hosted by the Hellenic Association of Medical Physicists (HAMP) in collaboration with the EFOMP and are summarized in this issue. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  14. Numerical Analysis for Structural Safety Evaluation of Butterfly Valves

    Science.gov (United States)

    Shin, Myung-Seob; Yoon, Joon-Yong; Park, Han-Yung

    2010-06-01

    Butterfly valves are widely used in current industry to control the fluid flow. They are used for both on-off and throttling applications involving large flows at relatively low operating pressure especially in large size pipelines. For the industrial application of butterfly valves, it must be ensured that the valve could be used safety under the fatigue life and the deformations produced by the pressure of the fluid. In this study, we carried out the structure analysis of the body and the valve disc of the butterfly valve and the numerical simulation was performed by using ANSYS v11.0. The reliability of valve is evaluated under the investigation of the deformation, the leak test and the durability of the valve.

  15. Blood compatibility of the jellyfish valve without anticoagulant.

    Science.gov (United States)

    Imachi, K; Mabuchi, K; Chinzei, T; Abe, Y; Imanishi, K; Suzukawa, M; Yonezawa, T; Kouno, A; Ono, T; Nozawa, H

    1991-01-01

    The blood compatibility of the jellyfish valve was studied. Artificial heart (AH) blood pumps incorporating jellyfish valves were connected to 18 goats as total artificial hearts (TAHs) and pumped for 1 to 125 days without anticoagulant or antiplatelet drugs. No thrombus was formed on the valve membrane or around the valve seat. Scanning electron microscopy showed almost no platelet deposition or microfibrin clot formation on the valve membrane, including its central region; the spokes of the valve seat were also free from platelet and microfibrin clots. No calcification was observed during these tests, and plasma free hemoglobin was between 2 and 7 mg/dl. The jellyfish valve revealed good blood compatibility, even without anticoagulant use.

  16. Low power valve actuation using trans-permanent magnetics

    Science.gov (United States)

    Duval, Luis Denit

    The subject of magnetic actuators is very broad, and encompasses a wide range of technologies, magnetic circuit topologies, and performance characteristics for an ever-increasing spectrum of applications. As a consequence of recent advances in soft and hard magnetic materials and developments in power electronics, microprocessors and digital control strategies, and the continuing demand for higher performance motion control systems, there appears to be more research and development activity in magnetic actuators for applications spanning all market sectors than at any time. In this dissertation, a rational approach for switching the states of permanent magnets through an on-board magnetization process is presented. The resulting dynamic systems are referred to as trans-permanent magnetic systems (T-PM). The first part of this research focuses on the governing equations needed for the analysis of T-PM systems. Their feasibility is demonstrated experimentally. In doing so, a method that has the potential of leading to new ultra-low power designs for electromechanical devices is introduced. In the second part of this research, the aforementioned developments in T-PM are applied to the problem of low power valves. Whereas alternate approaches to low power valve control may utilize latching mechanisms to maintain valve position during inactive periods, an approach that eliminates latching mechanisms is presented. Instead, the principles of T-PM are employed to switch the states of permanent magnets; the used of permanent magnets instead of electromagnets eliminates power consumption during inactive periods, thereby reducing power consumption to ultra-low levels. The magnets in a T-PM actuator are configured in a stack. The relationships between the strength and number of magnets in the stack and the stroke and resolution of the actuator are developed. This dissertation reports on the design and testing of a prototype valve actuator that uses a stack pf T-PM with

  17. 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.

  18. 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.

  19. Comparison of modified chandler, roller pump, and ball valve circulation models for in vitro testing in high blood flow conditions: application in thrombogenicity testing of different materials for vascular applications.

    Science.gov (United States)

    van Oeveren, Wim; Tielliu, Ignace F; de Hart, Jurgen

    2012-01-01

    Three different models, a modified Chandler loop, roller pump, and a new ball valve model (Hemobile), were compared with regard to intrinsic damage of blood components and activation of platelets. The Hemobile was used for testing of polymer tubes. High flow was not possible with the Chandler loop. The roller pump and the Hemobile could be adjusted to high flow, but he pump induced hemolysis. Platelet numbers were reduced in the roller pump and Chandler loop (P Dyneema Purity UHMWPE fiber and PET fiber based tubes, all showed hemolysis below 0.2% and reduced platelet count and function. Binding of fibrin and platelets was higer on PET, inflammatory markers were lowest on Dyneema Purity UHMWPE. We concluded that the Hemobile minimally affects blood and could be adjusted to high blood flows, simulating arterial shear stress. The Hemobile was used to measure hemocompatibility of graft material and showed Dyneema Purity UHMWPE fiber in many ways more hemocompatible than ePTFE and PET.

  20. Comparative Matched Outcome of Evolut-R vs CoreValve Transcatheter Aortic Valve Implantation.

    Science.gov (United States)

    Landes, Uri; Bental, Tamir; Barsheshet, Alon; Assali, Abid; Vaknin Assa, Hana; Levi, Amos; Orvin, Katia; Kornowski, Ran

    2017-02-01

    The Evolut-R (Medtronic, Inc) is a transcatheter aortic valve implantation (TAVI) system that was built on the well-established foundation of Medtronic's CoreValve device platform. Although already in extensive clinical utilization, it is unknown if the Evolut-R improves TAVI outcomes. Herein, we compared TAVI outcomes of the Evolut-R and CoreValve devices. A propensity score 1:1 matching was conducted on 358 Evolut-R patients (n = 75) and CoreValve patients (n = 283). Thirty-day outcomes were compared using Valve Academic Research Consortium (VARC)-2 criteria. A combined 30-day endpoint including all-cause death, stroke, major vascular complication, major bleeding, implantation failure, paravalvular leak (PVL) ≥ moderate, and new pacemaker implantation was also tested. The final study group included 146 patients (73 Evolut-R; 73 CoreValve). Post matching, baseline characteristics were similar between the two groups. Mean patient age was 82 ± 6 years, mean STS score was 5.2 ± 3.8, 72% were female, and 17% were deemed frail. Implantation success reached 99% with Evolut-R and 94% with CoreValve (P=.10). Both groups had low periprocedural stroke/myocardial infarction/mortality rates and there was also no difference in 30-day vascular complications (P=.18), bleeding (P=.37), PVL (P=.24), and new pacemaker (P=.14). The combined outcome rate was 24% with Evolut-R and 37% with CoreValve (P=.10). This study indicates that the efficacy and safety of the self-expandable second-generation Evolut-R transcatheter valve is at least comparable with the first-generation CoreValve. The observed improved performance in correct positioning of a single valve and the numerically lower chance to suffer a combined TAVI endpoint needs further investigation.

  1. Hybrid textile heart valve prosthesis: preliminary in vitro evaluation.

    Science.gov (United States)

    Vaesken, Antoine; Pidancier, Christian; Chakfe, Nabil; Heim, Frederic

    2016-09-22

    Transcatheter aortic valve implantation (TAVI) is nowadays a popular alternative technique to surgical valve replacement for critical patients. Biological valve tissue has been used in these devices for over a decade now with over 100,000 implantations. However, material degradations due to crimping for catheter insertion purpose have been reported, and with only 6-year follow-up, no information is available about the long-term durability of biological tissue. Moreover, expensive biological tissue harvesting and chemical treatment procedures tend to promote the development of synthetic valve leaflet materials. Textile polyester (PET) material is characterized by outstanding folding and strength properties combined with proven biocompatibility and could therefore be considered as a candidate to replace biological valve leaflets in TAVI devices. Nevertheless, the material should be preferentially partly elastic in order to limit water hammer effects at valve closing time and prevent exaggerated stress from occurring into the stent and the valve. The purpose of the present work is to study in vitro the mechanical as well as the hydrodynamic behavior of a hybrid elastic textile valve device combining non-deformable PET yarn and elastic polyurethane (PU) yarn. The hybrid valve properties are compared with those of a non-elastic textile valve. Testing results show improved hydrodynamic properties with the elastic construction. However, under fatigue conditions, the interaction between PU and PET yarns tends to limit the valve durability.

  2. 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.

  3. Aperture Valve for the Mars Organic Molecule Analyzer (MOMA)

    Science.gov (United States)

    Hakun, Claef F.; Engler, Charles D.; Barber, Willie E.; Canham, John S.

    2014-01-01

    NASA's participation in the multi-nation ExoMars 2018 Rover mission includes a critical astrobiology Mass Spectrometer Instrument on the Rover called the Mars Organic Molecule Analyzer (MOMA). The Aperture Valve is a critical electromechanical valve used by the Mass Spectrometer to facilitate the transfer of ions from Martian soil to the Mass Spectrometer for analysis. The MOMA Aperture Valve development program will be discussed in terms of the Initial valve design and subsequent improvements that resulted from prototype testing. The Initial Aperture Valve concept seemed promising, based on calculations and perceived merits. However, performance results of this design were disappointing, due to delamination of TiN and DLC coatings applied to the Titanium base metals, causing debris from the coatings to seize the valve. While peer reviews and design trade studies are important forums to vet a concept design, results from testing should not be underestimated.Despite the lack of development progress to meet requirements, valuable information from weakness discovered in the Initial Valve design was used to develop a second, more robust Aperture valve. Based on a check-ball design, the ETU flight valve design resulted in significantly less surface area to create the seal. Moreover, PVD coatings were eliminated in favor of hardened, nonmagnetic corrosion resistant alloys. Test results were impressive, with the valve achieving five orders of magnitude better sealing leak rate over end of life requirements. Cycle life was equally impressive, achieving 280,000 cycles without failure.

  4. How Heart Valves Evolve to Adapt to an Extreme-Pressure System: Morphologic and Biomechanical Properties of Giraffe Heart Valves.

    Science.gov (United States)

    Amstrup Funder, Jonas; Christian Danielsen, Carl; Baandrup, Ulrik; Martin Bibby, Bo; Carl Andelius, Ted; Toft Brøndum, Emil; Wang, Tobias; Michael Hasenkam, J

    2017-01-01

    Heart valves which exist naturally in an extreme-pressure system must have evolved in a way to resist the stresses of high pressure. Giraffes are interesting as they naturally have a blood pressure twice that of humans. Thus, knowledge regarding giraffe heart valves may aid in developing techniques to design improved pressure-resistant biological heart valves. Heart valves from 12 giraffes and 10 calves were explanted and subjected to either biomechanical or morphological examinations. Strips from the heart valves were subjected to cyclic loading tests, followed by failure tests. Thickness measurements and analyses of elastin and collagen content were also made. Valve specimens were stained with hematoxylin and eosin, elastic van Gieson stain, Masson's trichrome and Fraser-Lendrum stain, as well as immunohistochemical reactions for morphological examinations. The aortic valve was shown to be 70% (95% CI 42-103%) stronger in the giraffe than in its bovine counterpart (p giraffe aortic valve was found to be significantly stiffer than the bovine aortic valve (p giraffes contained significantly more collagen than those of calves. The elastin contents of the pulmonary valves (2.5%) and aortic valves (1.5%) were also higher in giraffes. The greater strength of the giraffe aortic valve is most likely due to a compact collagen construction. Both, collagen and elastin contents were higher in giraffes than in calves, which would make giraffe valves more resistant to the high-pressure forces. However, collagen also stiffens and thickens the valves. The mitral leaflets showed similar (but mostly insignificant) trends in strength, stiffness, and collagen content.

  5. CT images of lipomatosis of the ileocecal valve

    Energy Technology Data Exchange (ETDEWEB)

    Mitani, Takashi; Sato, Tadayuki; Fujita, Makoto; Narumi, Yoshifumi; Kuriyama, Keiko; Sakai, Yoshiko; Fujino, Yasusada

    1988-08-01

    Lipomatosis of the ileocecal valve, which is characterized by diffuse fatty deposition in the submucosa of the valve without encapsulation, usually appears as round or lobulated, smoothly outlined and sharply demarcated tumors on barium enema examination. These filling defects sometimes have presented problems of differential diagnosis with respect to malignant involvement. We have recently seen three cases of lipomatosis of the ileocecal valve. One is histologically proved and two are clinically diagnosed. CT images of those cases are discussed and inhomogeneous low density area in the ileocecal valve is suggestive of the lipomatosis.

  6. A Hybrid Tissue-Engineered Heart Valve.

    Science.gov (United States)

    Alavi, S Hamed; Kheradvar, Arash

    2015-06-01

    This study describes the efforts to develop and test the first hybrid tissue-engineered heart valve whose leaflets are composed of an extra-thin superelastic Nitinol mesh tightly enclosed by uniform tissue layers composed of multiple cell types. The trileaflet Nitinol mesh scaffolds underwent three-dimensional cell culture with smooth muscle and fibroblast/myofibroblast cells enclosing the mesh, which were finally covered by an endothelial cell layer. Quantitative and qualitative assays were performed to analyze the microstructure of the tissues. A tissue composition almost similar to that of natural heart valve leaflets was observed. The function of the valves and their Nitinol scaffolds were tested in a heart flow simulator that confirmed the trileaflet valves open and close robustly under physiologic flow conditions with an effective orifice area of 75%. The tissue-metal attachment of the leaflets once exposed to physiologic flow rates was tested and approved. Our preliminary results indicate that the novel hybrid approach with nondegradable scaffold for engineering heart valves is viable and may address the issues associated with current tissue-engineered valves developed with degradable scaffolds. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  7. Replaceable valve seat

    Science.gov (United States)

    Jordan, Raymond W.

    1992-01-01

    A valve with an O-ring, a disk seal, and a replaceable valve seat is presented. A groove in the bottom on the valve seat flange forms an inner and outer drip ledge with the inner and outer periphery of the flange. If leakage occurs at the valve seat O-ring, fluid droplets will form on the out drip ledge. If leakage occurs at the disk seal, fluid droplets will form on the inner drip ledge. A visual inspection of these drip ledges through an access port, or by a borescope placed in an inspection port, can discriminate between a leak which originates in the O-ring and a leak which originates in the disk seal. When conventional replaceable valve seats leak, fluid droplets form at the bottom on the valve seat. In the present invention, such a valve seat is modified by machining a groove on the bottom surface of the valve seat flange. This groove and the inner and outer surfaces of the flange intersect and form drip ledges. If leakage occurs at the valve seat seal, shown as an O-ring in the preferred embodiment, fluid droplets will form on the outer drip ledge. If leakage occurs at the valve disk seal, fluid droplets will form on the inner drip ledge. The drip ledges can be inspected either through an access port or by passing a borescope through a small inspection port in the valve case. Visual inspection of the bottom on the drip ledge will positively identify the required repair action.

  8. Design of Over Center Valves Based on Predictable Performance

    DEFF Research Database (Denmark)

    Hansen, M.R.; Andersen, T.O.; Pedersen, P.

    2004-01-01

    this assumption and an approach to design over center valve geometries that have negative flow forces is presented with emphasis on predictability. In conclusion it is made clear that negative flow forces in the over center valve cannot solve the instability problem in general, however, it might very well...

  9. Mitral Valve Prolapse

    Science.gov (United States)

    ... State SELECT YOUR LANGUAGE Español (Spanish) 简体中文 (Traditional Chinese) 繁体中文 (Simplified Chinese) Tiếng Việt (Vietnamese) Healthy Living for Heart.org ... valve syndrome . What happens during MVP? Watch an animation of mitral valve prolapse When the heart pumps ( ...

  10. Mitral Valve Disease

    Science.gov (United States)

    ... clots, but they also are less durable than mechanical valves and may need to be replaced in the future. Like mitral valve repair, replacement can be done minimally invasively or with traditional open heart surgery. Your medical team will discuss the advantages ...

  11. The students' ability in the mathematical literacy for uncertainty problems on the PISA adaptation test

    Science.gov (United States)

    Julie, Hongki; Sanjaya, Febi; Anggoro, Ant. Yudhi

    2017-08-01

    One of purposes of this study was to describe the solution profile of the junior high school students for the PISA adaptation test. The procedures conducted by researchers to achieve this objective were (1) adapting the PISA test, (2) validating the adapting PISA test, (3) asking junior high school students to do the adapting PISA test, and (4) making the students' solution profile. The PISA problems for mathematics could be classified into four areas, namely quantity, space and shape, change and relationship, and uncertainty. The research results that would be presented in this paper were the result test for uncertainty problems. In the adapting PISA test, there were fifteen questions. Subjects in this study were 18 students from 11 junior high schools in Yogyakarta, Central Java, and Banten. The type of research that used by the researchers was a qualitative research. For the first uncertainty problem in the adapting test, 66.67% of students reached level 3. For the second uncertainty problem in the adapting test, 44.44% of students achieved level 4, and 33.33% of students reached level 3. For the third uncertainty problem in the adapting test n, 38.89% of students achieved level 5, 11.11% of students reached level 4, and 5.56% of students achieved level 3. For the part a of the fourth uncertainty problem in the adapting test, 72.22% of students reached level 4 and for the part b of the fourth uncertainty problem in the adapting test, 83.33% students achieved level 4.

  12. [Related research on mechanical property of valve membrane in transcatheter bioprosthesis valve based on the chemical modification and cutting technology].

    Science.gov (United States)

    Chen, Dakai; Li, Yu; Luo, Qiyi; Liu, Baolin; Chen, Kangmin

    2014-08-01

    The aim of this research is to investigate the preparation method of valve membrane in transcatheter bio- prosthetic valve, and to study the effect of chemical modification and cutting technology to tensile property and suture force property of valve membrane. We carried out a series of processes to perform the tests, such as firstly to test the crosslinking degree of valve membrane using ninhydrin method, then to test the tensile property and suture force property by using Instron's biomechanicAl testing equipment, and then to observe the collagen fiber orientation in valve membrane using Instron's biomechanical testing equipment and using field emission scanning electron microscopy. The study indicated that after the chemical modification, the crosslinking degree, tensile strength and suture force strength increasing rate of valve membrane were 93.78% ± 3. 2%, (8.24 ± 0.79) MPa, 102%, respectively. The valve membrane had a better biomechanical property and would be expected to become valve membrane in transcatheter bioprosthesis valve.

  13. 46 CFR 56.20-15 - Valves employing resilient material.

    Science.gov (United States)

    2010-10-01

    ... 5 percent of its fully open flow rate or 15 percent divided by the square root of the nominal pipe... shutoff valve is required. (c) If a valve designer elects to use either a calculation or actual fire testing instead of material removal and pressure testing, the calculation must employ ISA-S75.02...

  14. Testing foreign language impact on engineering students' scientific problem-solving performance

    Science.gov (United States)

    Tatzl, Dietmar; Messnarz, Bernd

    2013-12-01

    This article investigates the influence of English as the examination language on the solution of physics and science problems by non-native speakers in tertiary engineering education. For that purpose, a statistically significant total number of 96 students in four year groups from freshman to senior level participated in a testing experiment in the Degree Programme of Aviation at the FH JOANNEUM University of Applied Sciences, Graz, Austria. Half of each test group were given a set of 12 physics problems described in German, the other half received the same set of problems described in English. It was the goal to test linguistic reading comprehension necessary for scientific problem solving instead of physics knowledge as such. The results imply that written undergraduate English-medium engineering tests and examinations may not require additional examination time or language-specific aids for students who have reached university-entrance proficiency in English as a foreign language.

  15. Transcatheter aortic valve implantation for bicuspid aortic valve stenosis.

    Science.gov (United States)

    Hamdan, Ashraf; Kornowski, Ran

    2015-08-01

    In Preprocedural CT, patients with BAV have larger aortic annulus perimeters, and more calcified valves compared with TAV. In patients with BAV, self-expandable valves were under-expand and balloon-expandable valves have a trend toward increased rates of postimplantation AR grade. Self-expandable valves have higher postprocedural gradient in BAV compared with TAV. © 2015 Wiley Periodicals, Inc.

  16. Robustness to non-normality of various tests for the one-sample location problem

    Directory of Open Access Journals (Sweden)

    Michelle K. McDougall

    2004-01-01

    Full Text Available This paper studies the effect of the normal distribution assumption on the power and size of the sign test, Wilcoxon's signed rank test and the t-test when used in one-sample location problems. Power functions for these tests under various skewness and kurtosis conditions are produced for several sample sizes from simulated data using the g-and-k distribution of MacGillivray and Cannon [5].

  17. Effect of transcatheter aortic valve size and position on valve-in-valve hemodynamics: An in vitro study.

    Science.gov (United States)

    Azadani, Ali N; Reardon, Michael; Simonato, Matheus; Aldea, Gabriel; Nickenig, Georg; Kornowski, Ran; Dvir, Danny

    2017-06-01

    Transcatheter heart valve implantation in failed aortic bioprostheses (valve-in-valve [ViV]) is an increasingly used therapeutic option for high-risk patients. However, high postprocedural gradients are a significant limitation of aortic ViV. Our objective was to evaluate Medtronic CoreValve Evolut R ViV hemodynamics in relation to the degree of device oversizing and depth of implantation. Evolut R devices of 23 and 26 mm were implanted within 21-, 23-, and 25-mm Hancock II bioprostheses. Small and gradual changes in implantation depth were attempted. Hemodynamic testing was performed in a pulse duplicator under ISO-5840 standard. A total of 47 bench-testing experiments were performed. The mean gradient of the 26-mm Evolut R in 23- and 25-mm Hancock II was lower than 23-mm Evolut R (P  17.5 mm. The current comprehensive bench-testing assessment demonstrates the importance of both transcatheter heart valve size and device position for the attainment of optimal hemodynamics during ViV procedures. Additional in vitro testing may be required to develop hemodynamics-based guidelines for device sizing in ViV procedures in degenerated surgical bioprostheses. Copyright © 2017 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

  18. 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.

  19. Experimental study of asymmetric heart valve prototype

    Science.gov (United States)

    Vukicevic, M.; Fortini, S.; Querzoli, G.; Cenedese, A.; Pedrizzetti, G.

    2011-11-01

    The mechanical heart valves (MHVs) are extremely important medical devices, commonly used for diseased heart valves replacement. Despite the long term of use and constant design refinement, the MHVs are very far from ideal and their performance is very diverse from that of the native ones. It has been approved that small variations in geometry of valvular leaflets influence the significant change in the intraventricular vortical flow, known as one of the most important factors for the overall functionality of the heart. We have experimentally examined the home-made heart valve prototypes, exclusively modeled for the mitral valve replacement. The performance and energetic properties of the prototypes have been compared with those in the presence of standard MHVs. The analysis was based on the testing of intraventricular fluid dynamics, usually missing criteria for the quality of the valve performance. It has been shown that the asymmetric prototype, with unequal leaflets and D-shaped orifice produces flow patterns and energetic properties close to those found in the healthy subjects. Thus, the break of symmetry in the standard bi-leaflet MHV prosthesis, at least from the fluid dynamics point of view, is worthwhile to be considered for the design of MHVs for the mitral valve replacement.

  20. 49 CFR 40.269 - What problems cause an alcohol test to be cancelled unless they are corrected?

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false What problems cause an alcohol test to be... Transportation PROCEDURES FOR TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Problems in Alcohol Testing § 40.269 What problems cause an alcohol test to be cancelled unless they are corrected? As a BAT...

  1. 49 CFR 40.203 - What problems cause a drug test to be cancelled unless they are corrected?

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false What problems cause a drug test to be cancelled... PROCEDURES FOR TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Problems in Drug Tests § 40.203 What problems cause a drug test to be cancelled unless they are corrected? (a) As the MRO, when a...

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

    Science.gov (United States)

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

    2010-01-01

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

  3. Long-term performance of motor-operated valves

    Energy Technology Data Exchange (ETDEWEB)

    Scarbrough, T.G.

    1996-12-01

    The U.S. Nuclear Regulatory Commission (NRC) requires that motor-operated valves (MOVs) important to safety be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions to be performed. Despite these requirements, operating experience and research revealed problems with the performance of MOVs in operating nuclear power plants. In response to the concerns about MOV performance, the NRC issued Generic Letter (GL) 89-10, {open_quotes}Safety-Related Motor-Operated Valve Testing and Surveillance,{close_quotes} and its supplements. Most licensees have completed the aspects of their GL 89-10 programs associated with the review of MOV design bases, verification of MOV switch settings initially, testing of MOVs under design-basis conditions where practicable, and improvement of evaluations of MOV failures and necessary corrective action. Licensees are establishing processes to ensure that the long-term aspects of their MOV programs, such as periodic verification of MOV capability and the trending of MOV problems, are maintained. The NRC staff is developing a generic letter to address periodic verification of MOV design-basis capability.

  4. 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.

  5. Noise generated by flow through large butterfly valves

    Science.gov (United States)

    Huff, Ronald G.

    1987-01-01

    A large butterfly valve (1.37 m diam) was acoustically tested to measure the noise generated and propagating in both the upstream and downstream directions. The experimental investigation used wall mounted pressure transducers to measure the fluctuating component of the pipe static pressure upstream and downstream of the valve. Microphones upstream of the pipe inlet and located in a plenum were used to measure the noise radiated from the valve in the upstream direction. Comparison of the wall pressure downstream of the valve to a prediction were made. Reasonable agreement was obtained with the valve operating at a choked condition. The noise upstream of the valve is 30 dB less than that measured downstream.

  6. Dynamic Economic Dispatch Using Hybrid DE-SQP for Generating Units with Valve-Point Effects

    OpenAIRE

    A. M. Elaiw; Xia, X; A.M.Shehata

    2012-01-01

    This paper presents hybrid differential evolution (DE) and sequential quadratic programming (SQP) for solving the dynamic economic dispatch (DED) problem for generating units with valve-point effects. DE is used as a global optimizer and SQP is used as a fine tuning to determine the optimal solution at the final. The feasibility of the proposed method is validated with five-and ten-unit test systems. Results obtained by DE-SQP method are compared with other techniques in the literature.

  7. Problem-Solving Test: RNA and Protein Synthesis in Bacteriophage-Infected "E. coli" Cells

    Science.gov (United States)

    Szeberenyi, Jozsef

    2008-01-01

    The classic experiment presented in this problem-solving test was designed to identify the template molecules of translation by analyzing the synthesis of phage proteins in "Escherichia coli" cells infected with bacteriophage T4. The work described in this test led to one of the most seminal discoveries of early molecular biology: it dealt a…

  8. Setting Specific Criteria for Scoring Word Problems in Mathematics: Effects on Test Validity and Reliability.

    Science.gov (United States)

    Ibe, Milagros D.

    1983-01-01

    This study investigated the effects of specific criteria for marking a test on its reliability and validity. Eight algebra word problems were administered to grade 10 students. The objectivity of scoring criteria improved the reliability of the test, but did not affect its validity. (MNS)

  9. Study of safety relief valve operation under ATWS conditions. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Hutmacher, E.S.; Nesmith, B.J.; Brukiewa, J.B.

    1979-06-25

    A literature survey and analysis project has been performed to determine if recent (since mid-1975) data has been reported which could influence the current approach to predicting PWR relief valve capacity under ATWS conditions. This study was conducted by the Energy Technology Engineering Center for NRC. Results indicate that the current relief valve capacity model tends to predict less capacity than actually obtains; however, no experimental verification at PWR ATWS conditions was found. Other project objectives were to establish the availability of methods for evaluating reaction forces and back pressure effects on relief valve capacity, and to determine if facilities exist which are capable of testing PWR relief valves at ATWS conditions.

  10. FLUID MECHANICS OF ARTIFICIAL HEART VALVES

    OpenAIRE

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

    2009-01-01

    1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mecha...

  11. Balloon expandable transcatheter heart valves for native mitral valve disease with severe mitral annular calcification.

    Science.gov (United States)

    Guerrero, Mayra; Urena, Marina; Pursnani, Amit; Wang, Dee D; Vahanian, Alec; O'Neill, William; Feldman, Ted; Himbert, Dominique

    2016-06-01

    Patients with mitral annular calcification (MAC) have high surgical risk for mitral valve replacement due to associated comorbidities and technical challenges related to calcium burden, precluding surgery in many patients. Transcatheter mitral valve replacement (TMVR) with the compassionate use of balloon expandable aortic transcatheter heart valves has been used in this clinical scenario. The purpose of this review was to summarize the early experience including successes and failures reported. TMVR might evolve into an acceptable alternative for selected patients with severe MAC who are not candidates for conventional mitral valve surgery. However, this field is at a very early stage and the progress will be significantly slower than the development of transcatheter aortic valve replacement due to the complexity of the mitral valve anatomy and its pathology. Optimizing patient selection process by using multimodality imaging tools to accurately measure the mitral valve annulus and evaluate the risk of left ventricular outflow tract obstruction is essential to minimize complications. Strategies for treating and preventing left ventricular outflow tract obstruction are being tested. Similarly, carefully selecting candidates avoiding patients at the end of their disease process, might improve the overall outcomes.

  12. 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.

  13. Mitral valve surgery - open

    Science.gov (United States)

    ... be able to store blood in the blood bank for transfusions during and after your surgery. Ask ... stroke. Valves made from human or animal tissue fail over time. They have an average lifespan of ...

  14. Valve Repair or Replacement

    Science.gov (United States)

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

  15. Aortic Valve Regurgitation

    Science.gov (United States)

    ... valves. Rheumatic fever. Rheumatic fever — a complication of strep throat and once a common childhood illness in the ... a severe sore throat, see a doctor. Untreated strep throat can lead to rheumatic fever. Fortunately, strep throat ...

  16. Shuttle communication systems compatibility and performance tests. [transponder, range error, and power amplifier problems

    Science.gov (United States)

    Bromley, L. K.; Travis, A. D.

    1980-01-01

    The compatibility and performance of the Shuttle communications system must be certified prior to operational missions. For this purpose, NASA has established the Electronics Systems Test Laboratory (ESTL) at the Johnson Space Center. This paper discusses the Shuttle communications system compatibility and performance testing being performed in the ESTL. The ESTL system verification test philosophy, including capabilities, procedures, and unique testing equipment are summarized. Summaries of the significant results of compatibility and performance tests of the Orbiter/Space-flight Tracking and Data Network, Orbiter/Air Force Remote Tracking Station, Orbiter/Tracking and Data Relay Satellite System and Orbiter/Shuttle Launch Support System interfaces are presented. The ESTL's unique ability to locate potential communication problems and participate in the resolution of these problems are discussed in detail.

  17. Experimental Validation of Mathematical Framework for Fast Switching Valves used in Digital Hydraulic Machines

    DEFF Research Database (Denmark)

    Nørgård, Christian; Roemer, Daniel Beck; Bech, Michael Møller

    2015-01-01

    A prototype of a fast switching valve designed for a digital hydraulic transmission has been manufactured and experimentally tested. The valve is an annular seat valve composed of a plunger connected with a direct electromagnetic moving coil actuator as the force producing element. Based on an el......A prototype of a fast switching valve designed for a digital hydraulic transmission has been manufactured and experimentally tested. The valve is an annular seat valve composed of a plunger connected with a direct electromagnetic moving coil actuator as the force producing element. Based...... on an elaborate optimization method the valve is designed to maximize the efficiency of a digital hydraulic motor targeted to a wind turbine transmission system. The optimisation method comprises a mathematical framework which predicts a valve switching time of approximately 1 ms with a peak actuator input power...

  18. Intelligence and Creativity in Problem Solving: The Importance of Test Features in Cognition Research

    Science.gov (United States)

    Jaarsveld, Saskia; Lachmann, Thomas

    2017-01-01

    This paper discusses the importance of three features of psychometric tests for cognition research: construct definition, problem space, and knowledge domain. Definition of constructs, e.g., intelligence or creativity, forms the theoretical basis for test construction. Problem space, being well or ill-defined, is determined by the cognitive abilities considered to belong to the constructs, e.g., convergent thinking to intelligence, divergent thinking to creativity. Knowledge domain and the possibilities it offers cognition are reflected in test results. We argue that (a) comparing results of tests with different problem spaces is more informative when cognition operates in both tests on an identical knowledge domain, and (b) intertwining of abilities related to both constructs can only be expected in tests developed to instigate such a process. Test features should guarantee that abilities can contribute to self-generated and goal-directed processes bringing forth solutions that are both new and applicable. We propose and discuss a test example that was developed to address these issues. PMID:28220098

  19. Intelligence and Creativity in Problem Solving: The Importance of Test Features in Cognition Research.

    Science.gov (United States)

    Jaarsveld, Saskia; Lachmann, Thomas

    2017-01-01

    This paper discusses the importance of three features of psychometric tests for cognition research: construct definition, problem space, and knowledge domain. Definition of constructs, e.g., intelligence or creativity, forms the theoretical basis for test construction. Problem space, being well or ill-defined, is determined by the cognitive abilities considered to belong to the constructs, e.g., convergent thinking to intelligence, divergent thinking to creativity. Knowledge domain and the possibilities it offers cognition are reflected in test results. We argue that (a) comparing results of tests with different problem spaces is more informative when cognition operates in both tests on an identical knowledge domain, and (b) intertwining of abilities related to both constructs can only be expected in tests developed to instigate such a process. Test features should guarantee that abilities can contribute to self-generated and goal-directed processes bringing forth solutions that are both new and applicable. We propose and discuss a test example that was developed to address these issues.

  20. Mammalian Toxicology Testing: Problem Definition Study, Technology Changes Impact on Testing Requirements.

    Science.gov (United States)

    1981-01-01

    specific activity. I anticipate the major change in equipment in nutagenicity testing to be the improved sensitivity of radiotracer techniques. 20...three-day meeting on this subject area will be held at Raleigh, NC, in February, 1981. The purpose of this industry /government sponsored symposium will be... OIL : SCROTUM op a....... TOAC MOUTH m K.XRAY :SKIN COAL TAR: SKIN ~~oAREN -fIIL SKIN SOOT: SCROTUM 860o 1900 1920 1940 1960 1900 FIGURE 1 ENVIRONMENTAL

  1. Evaluation of mitral valve replacement anchoring in a phantom

    Science.gov (United States)

    McLeod, A. Jonathan; Moore, John; Lang, Pencilla; Bainbridge, Dan; Campbell, Gordon; Jones, Doug L.; Guiraudon, Gerard M.; Peters, Terry M.

    2012-02-01

    Conventional mitral valve replacement requires a median sternotomy and cardio-pulmonary bypass with aortic crossclamping and is associated with significant mortality and morbidity which could be reduced by performing the procedure off-pump. Replacing the mitral valve in the closed, off-pump, beating heart requires extensive development and validation of surgical and imaging techniques. Image guidance systems and surgical access for off-pump mitral valve replacement have been previously developed, allowing the prosthetic valve to be safely introduced into the left atrium and inserted into the mitral annulus. The major remaining challenge is to design a method of securely anchoring the prosthetic valve inside the beating heart. The development of anchoring techniques has been hampered by the expense and difficulty in conducting large animal studies. In this paper, we demonstrate how prosthetic valve anchoring may be evaluated in a dynamic phantom. The phantom provides a consistent testing environment where pressure measurements and Doppler ultrasound can be used to monitor and assess the valve anchoring procedures, detecting pararvalvular leak when valve anchoring is inadequate. Minimally invasive anchoring techniques may be directly compared to the current gold standard of valves sutured under direct vision, providing a useful tool for the validation of new surgical instruments.

  2. Confusion and clairvoyance: some remarks on the composite hypothesis testing problem

    Science.gov (United States)

    Theiler, James

    2012-06-01

    This paper discusses issues related to the inherent ambiguity of the composite hypothesis testing problem, a problem that is central to the detection of target signals in cluttered backgrounds. In particular, the paper examines the recently proposed method of continuum fusion (which, because it combines an ensemble of clairvoyant detectors, might also be called clairvoyant fusion), and its relationship to other strategies for composite hypothesis testing. A specific example involving the affine subspace model adds to the confusion by illustrating irreconcilable differences between Bayesian and non-Bayesian approaches to target detection.

  3. A new concept in the sewing rings for mechanical heart valves.

    Science.gov (United States)

    Kurian, Mathew V; Umasankar, Payanam R; Sabareeswaran, Arumugam; Shenoy, Sachin J; Subban, Vijayakumar; Joseph, Mathew K

    2012-08-01

    Valve-associated complications challenge the quality of life and longevity after heart valve replacement. Inappropriate healing may be a contributing factor. To evaluate a new design mechanical heart valve in an animal model. The new valve was fabricated by substituting the sewing ring with an inbuilt suture ridge and an overlying fabric flap. It improved the effective orifice area. Animal experiments were performed on pigs to compare this valve with standard valve models. The animals were kept on dual antiplatelet drugs. Six of the 8 test animals survived the observation period of 140 days compared to 2 of the 6 controls. Among the test valves, one had thrombosis and 3 had significant tissue hyperplasia, whereas 5 control valves had thrombosis associated with significant tissue hyperplasia. Three test valves had paravalvular defects compared to none in the control group. Histology showed good tissue incorporation of the fabric flap of the test valves, whereas the control valves had tissue infiltration limited to the peripheral fabric layer of the sewing ring. The new valve has improved effective orifice area, and the animal study showed better survival, good healing, and a lower incidence of thrombosis and tissue hyperplasia.

  4. Valve position tracking for soft landing of electromechanical camless valvetrain

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, W. [Siemens AG, Erlangen (Germany); Stefanopoulou, A.G. [University of Michigan, Ann Arbor, MI (United States). Dept. of Mechanical Engineering

    2001-07-01

    Variable valve opening and closing allows improvements of internal combustion engines and requires precise control of the camless valvetrain actuator. In this paper the valve position tracking in electromechanical camless valvetrains (EMCV) is considered. One of the main problems in the EMCV actuator is the noise and wear associated with high contact velocities during the closing and opening of the valve. The contact velocity of the actuator and the valve can be reduced, and thus, noise and wear, by designing a tracking controller that consists of a linear feedback and an iterative learning controller (ILC). With the ILC methodology every cycle the feedforward signal of the feedback controller is updated based on the error between the actual valve position and the desired position. The methodology is reviewed and simulation results are presented. (author)

  5. Valve position tracking for soft landing of electromechanical camless valvetrain

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, W. [Siemens AG, Erlangen (Germany); Stefanopoulou, A.G. [Michigan Univ., Ann Arbor, MI (United States). Dept. of Mechanical Engineering

    2001-07-01

    Variable valve opening and closing allows improvements of internal combustion engines and requires precise control of the camless valvetrain actuator. In this paper the valve position tracking in electromechanical camless valvetrains (EMCV) is considered. One of the main problems in the EMCV actuator is the noise and wear associated with high contact velocities during the closing and opening of the valve. The contact velocity of the actuator and the valve can be reduced, and thus, noise and wear, by designing a tracking controller that consists of a linear feedback and an iterative learning controller (ILC). With the ILC methodology every cycle the feedforward signal of the feedback controller is updated based on the error between the actual valve position and the desired position. The methodology is reviewed and simulation results are presented. (orig.)

  6. How Is Heart Valve Disease Treated?

    Science.gov (United States)

    ... as well as surgery for adults who have aortic valve stenosis. Doctors often use balloon valvuloplasty to repair valve stenosis in infants and children. Replacing Heart Valves Sometimes heart valves can’t ...

  7. How Is Heart Valve Disease Diagnosed?

    Science.gov (United States)

    ... as well as surgery for adults who have aortic valve stenosis. Doctors often use balloon valvuloplasty to repair valve stenosis in infants and children. Replacing Heart Valves Sometimes heart valves can’t ...

  8. 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....

  9. Patch testing with markers of fragrance contact allergy. Do clinical tests correspond to patients' self-reported problems?

    DEFF Research Database (Denmark)

    Johansen, J D; Andersen, T F; Veien, N

    1997-01-01

    significant association was found between reporting a history of visible skin symptoms from using scented products and a positive patch test to the fragrance mix, whereas no such relationship could be established to the Peru balsam in univariate or multivariate analysis. Our results suggest that the role...... of Peru balsam in detecting relevant fragrance contact allergy is limited, while most fragrance mix-positive patients are aware that the use of scented products may cause skin problems....

  10. Variable Valve Timing Scheduling in a 4-Stroke Internal Combustion Cylinder Utilizing Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Sepehr Bapiri

    2017-09-01

    Full Text Available The apparently simple structure of a four-stroke internal combustion cylinder belies the complicated problem of optimizing valve operation in response to a change in crankshaft rotation speed. The objective of this study was to determine the cylinder pressure for valve event angles in order to determine the optimal strategy for the timing of valve events when independently-actuated valves are available. In this work, an artificial neural network is applied to create a prediction matrix to anticipate the best variable valve timing approach according to rotation speed.

  11. Carbon Fiber Reinforced Carbon Composites Rotary Valves for Internal Combustion Engines

    Science.gov (United States)

    Northam, G. Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

    1999-01-01

    Carbon fiber reinforced carbon composite rotary, sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or warp-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties, do not present the sealing and lubrication problems that have prevented rotary, sleeve, and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

  12. Carbon Fiber Reinforced Carbon Composite Rotary Valve for an Internal Combustion Engine

    Science.gov (United States)

    Northam, G.Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

    2000-01-01

    Carbon fiber reinforced carbon composite rotary sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or wrap-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties do not present the sealing and lubrication problems that have prevented rotary sleeve and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

  13. Patch testing with markers of fragrance contact allergy. Do clinical tests correspond to patients' self-reported problems?

    DEFF Research Database (Denmark)

    Johansen, J D; Andersen, T F; Veien, Niels

    1997-01-01

    The aim of the present study was to investigate the relationship between patients' own recognition of skin problems using consumer products and the results of patch testing with markers of fragrance sensitization. Eight hundred and eighty-four consecutive eczema patients, 18-69 years of age, filled...... significant association was found between reporting a history of visible skin symptoms from using scented products and a positive patch test to the fragrance mix, whereas no such relationship could be established to the Peru balsam in univariate or multivariate analysis. Our results suggest that the role...

  14. A Novel EP Approach for Power Economic Dispatch with Valve-Point Effects and Multiple Fuel Options

    Directory of Open Access Journals (Sweden)

    P.S. Manoharan

    2008-06-01

    Full Text Available This paper presents a novel approach to economic dispatch problems with valve point effects and multiple fuel options using a hybrid evolutionary programming method. Determination of global optimum solution for the practical economic dispatch problem having non smooth cost functions is difficult by using conventional mathematical approaches. Hence several evolutionary algorithm methods were proposed to solve this problem. In this paper, EP-LMO (Evolutionary Programming with Levenberg-Marquardt Optimization technique is proposed to solve economic dispatch problems with valve point effects and multiple fuel options. The EP-LMO is developed in such a way that a simple evolutionary programming (EP is applied as a base level search to find the direction of the optimal global region. And Levenberg-Marquardt Optimization (LMO method is used as a fine tuning to determine the optimal solution. To illustrate the efficiency and effectiveness of the proposed approach, two bench mark problems are considered. First test problem considers multiple fuel options and next problem addresses both valve-point effects and multi-fuel options. To validate the obtained results, the proposed method is compared with the results of conventional numerical methods, Modified Hop-field Neural network, Evolutionary Programming approaches, Modified PSO, Improved PSO and Improved Genetic Algorithm with multiplier updating (IGA_MUmethod.

  15. Midterm Results of Aortic Valve Replacement with Cryopreserved Homografts

    Directory of Open Access Journals (Sweden)

    Emre Özker

    2012-06-01

    Full Text Available Objective: The aim of this study was to analyze the midterm clinical results of aortic valve replacement with cryopreserved homografts.Materials and Methods: Aortic valve replacement was performed in 40 patients with cryopreserved homograft. The indications were aortic valve endocarditis in 20 patients (50%, truncus arteriosus in 6 patients (15%, and re-stenosis or regurtitation after aortic valve reconstruction in 14 (35% patients. The valve sizes ranged from 10 to 27mm. A full root replacement technique was used for homograft replacement in all patients.Results: The 30-day postoperative mortality rate was 12.5% (5 patients. There were four late deaths. Only one of them was related to cardiac events. Overall mortality was 22.5%. Thirty-three patients were followed up for 67±26 months. Two patients needed reoperation due to aortic aneurysm caused by endocarditis. The mean transvalvular gradient significantly decreased after valve replacement (p<0.003. The last follow up showed that the 27 (82% patients had a normal left ventricular function.Conclusion: Cryopreserved homografts are safe alternatives to mechanical valves that can be used when there are proper indications. Although it has a high perioperative mortality rate, cryopreserved homograft implantation is an alternative for valve replacement, particularly in younger patients and for complex surgical problems such as endocarditis that must be minimalized.

  16. Problem-solving deficits in alcoholics: evidence from the California Card Sorting Test.

    Science.gov (United States)

    Beatty, W W; Katzung, V M; Nixon, S J; Moreland, V J

    1993-11-01

    In an attempt to clarify the nature of the problem-solving deficits exhibited by chronic alcoholics, the California Card Sorting Test (CCST) and other measures of abstraction and problem solving were administered to 23 alcoholics and 16 nonalcoholic controls, equated for age, education and vocabulary. On the CCST, the alcoholics exhibited three types of deficits which appeared to be relatively independent. First, the alcoholics generated and identified fewer correct concepts than controls, although they executed concepts normally when cued by the examiner. Second, the alcoholics made more perseverative sorting responses and perseverative verbal explanations for their sorting behavior than did controls. Third, alcoholics provided less complete verbal explanations of the concepts that they correctly generated or identified. The differential importance of these factors on various measures of problem solving may help to explain the varied patterns of inefficient problem solving exhibited by alcoholics.

  17. Transvalvular pressure gradients for different methods of mitral valve repair: only neochordoplasty achieves native valve gradients.

    Science.gov (United States)

    Jahren, Silje Ekroll; Hurni, Samuel; Heinisch, Paul Philipp; Winkler, Bernhard; Obrist, Dominik; Carrel, Thierry; Weber, Alberto

    2018-02-01

    Many surgical and interventional methods are available to restore patency for patients with degenerative severe mitral valve regurgitation. Leaflet resection and neochordoplasty, which both include ring annuloplasty, are the most frequently performed techniques for the repair of posterior mitral leaflet flail. It is unclear which technique results in the best haemodynamics. In this study, we investigated the effect of different mitral valve reconstruction techniques on mitral valve haemodynamics and diastolic transvalvular pressure gradient in an ex vivo porcine model. Eight porcine mitral valves were tested under pulsatile flow conditions in an in vitro pulsatile flow loop for haemodynamic quantification. Severe acute posterior mitral leaflet flail was created by resecting the posterior marginal chorda. The acute mitral valve regurgitation was corrected using 4 different repair techniques, in each valve, in a strictly successive order: (i) neochordoplasty with polytetrafluoroethylene sutures alone and (ii) with ring annuloplasty, (iii) edge-to-edge repair and (iv) triangular leaflet resection, both with ring annuloplasty. Valve haemodynamics were measured and quantified for all valve configurations (native, rupture and each surgical reconstruction). The results were analysed using a validated statistical linear mixed model, and the P-values were calculated using a 2-sided Wald test. All surgical reconstruction techniques were able to sufficiently correct the acute mitral valve regurgitation. Neochordoplasty without ring annuloplasty was the only reconstruction technique that resulted in haemodynamic properties similar to the native mitral valve (P-values from 0.071 to 0.901). The diastolic transvalvular gradient remained within the physiological range for all reconstructions but was significantly higher than in the native valve for neochordoplasty with ring annuloplasty (P < 0.000), edge-to-edge repair (P < 0.000) and leaflet resection (P < 0

  18. Effectiveness of rivaroxaban for thromboprophylaxis of prosthetic heart valves in a porcine heterotopic valve model.

    Science.gov (United States)

    Greiten, Lawrence E; McKellar, Stephen H; Rysavy, Joseph; Schaff, Hartzell V

    2014-05-01

    Warfarin is used to reduce the risk of stroke and thromboembolic complications in patients with mechanical heart valves. Yet, despite frequent blood testing, its poor pharmacokinetic and pharmacodynamic profiles often result in variable therapeutic levels. Rivaroxaban is a direct competitive factor Xa inhibitor that is taken orally. It inhibits the active site of factor Xa without the need for the cofactor antithrombin, and thus, its mechanism of action is differentiated from that of the fractionated heparins and indirect factor Xa inhibitors. No in vivo data exist regarding the effectiveness of rivaroxaban in preventing thromboembolic complications of mechanical heart valves. We tested the hypothesis that rivaroxaban is as effective as enoxaparin for thromboprophylaxis of mechanical valves that use a previously described heterotopic aortic valve porcine model. A modified bileaflet mechanical valved conduit that bypassed the native, ligated descending thoracic aorta was implanted into 30 swine. Postoperatively, the animals were randomly assigned to groups receiving no anticoagulation (n = 10), enoxaparin at 2 mg/kg subcutaneously twice daily (n = 10) or rivaroxaban at 2 mg/kg orally twice daily (n = 10). The amount of valve thrombus was measured on post-implantation day 30 as the primary end point. Quantitative evaluation of radiolabelled platelet deposition on the valve prostheses was done and embolic and haemorrhagic events were measured as secondary end points. Animals with no anticoagulation had a thrombus mean of 759.9 mg compared with 716.8 mg with enoxaparin treatment and 209.6 mg with rivaroxaban treatment (P = 0.05 for enoxaparin vs rivaroxaban). Similarly, the mean number of platelets deposited on the valve prosthesis was lower in the rivaroxaban group (6.13 × 10(9)) than in the enoxaparin group (3.03 × 10(10)) (P = 0.03). In this study, rivaroxaban was more effective than enoxaparin for short-term thromboprophylaxis of mechanical valve prosthetics in

  19. The Relationship between Test Anxiety, Epistemological Beliefs and Problem Solving among Students

    Science.gov (United States)

    Mehdinezhad, Vali; Bamari, Zeinab

    2015-01-01

    The purpose of this study was to investigate the test anxiety, epistemological beliefs and problem solving among students. The target population of the current research was all the students of University of Sistan and Baluchestan in the academic year 2013-2014 and the number of the sample was 375. They were selected using a classified and simple…

  20. Australian NAPLAN Testing: In What Ways Is This a "Wicked" Problem?

    Science.gov (United States)

    Johnston, Jenny

    2017-01-01

    This article employs Rittel and Webber's "wicked" problem as a heuristic device for enhancing understanding about National Assessment Program--Literacy and Numeracy (NAPLAN) testing in the Australian education context. Using a research project with seven independent schools in New South Wales, Australia, which analysed NAPLAN data from…

  1. Test-Retest Reliability of a Tutor Evaluation Form Used in a Problem-Based Curriculum.

    Science.gov (United States)

    Hay, John A.

    1997-01-01

    A study examined the test-retest reliability of 30 student evaluations of tutors in a problem-based learning curriculum at McMaster University in Hamilton, Ontario. Results were used for the improvement of reliability of the instrument. (JOW)

  2. A Problem That Led to Developing Video Administration of the GATB for Testing at Multiple Sites.

    Science.gov (United States)

    Simmons, Ernest W.

    As developer and custodian of the General Aptitude Test Battery (GATB), the U.S. Department of Labor (USDOL) is responsible for ensuring that its use meets established professional standards. Considering the logistical problems of overseeing the use of the GATB at more than 2,000 separate sites, the USDOL has confronted a monumental task in the…

  3. Reduction of the suction losses through reed valves in hermetic reciprocating compressors using a magnet coil

    Science.gov (United States)

    Hopfgartner, J.; Posch, S.; Zuber, B.; Almbauer, R.; Krischan, K.; Stangl, S.

    2017-08-01

    Reed valves are widely used in hermetic reciprocating compressors and are responsible for a large part of the thermodynamic losses. Especially, the suction valve, which is opened nearly during the whole suction stroke, has a big potential for improvement. Usually, suction valves are opened only by vacuum created by the moving piston and should be closed before the compression stroke starts to avoid a reversed mass-flow through the valve. Therefore, the valves are prestressed, which results on the other hand in a higher flow resistance. In this work, a suction valve is investigated, which is not closed by the preload of the valve but by an electromagnetic coil located in the suction muffler neck. Shortly before the piston reaches its bottom dead centre, voltage is applied to the coil and a magnetic force is generated which pulls the valve shut. Thereby, the flow resistance through the valve can be reduced by changing the preload on the reed valve because it is no longer needed to close the valve. The investigation of this adapted valve and the electromagnetic coil is firstly done by numerical simulations including fluid structure interactions of the reed valves of a reciprocating compressor and secondly by experiments made on a calorimeter test bench.

  4. Design of Bidirectional Check Valve for Discrete Fluid Power Force System for Wave Energy Converters

    DEFF Research Database (Denmark)

    Hansen, Anders Hedegaard; Pedersen, Henrik C.; Andersen, Torben Ole

    2014-01-01

    introduces large switching losses, especially when large pressure difference is present across the valves in the manifold. The current paper therefore focus on designing a bidirectional check valve for use in the switching manifold of the discrete force systems. The use of the bidirectional check valve...... enables passive force switching under minimal pressure difference, hence minimal energy loss. The bidirectional check valve is designed with a rated flow in the range of 1000L/min@5bar. The flow direction of the bidirectional check valve is set by the setting the pilot pressure. This paper presents...... a functionality test of a 125 L/min@5bar bidirectional check, leading to the design and modelling of a bidirectional check valve for ocean wave energy. It shows that a feasible bidirectional check valve may be configured by employing a multi-poppet topology for the main stage and utilising a 3/2 switching valve...

  5. Safety valve for offshore borehole

    Energy Technology Data Exchange (ETDEWEB)

    McGill, H.L.; Randermann, E. Jr.; Musik, O.J.

    1977-10-06

    The invention concerns a new and improved submarine safety valve with a valve element which rotate, which can be used, in emergencies, to separate the wound-up piping which extends into the borehole and to close the production line.

  6. Diseases of the Tricuspid Valve

    Science.gov (United States)

    ... diseases of the tricuspid valve are regurgitation and stenosis. Tricuspid Regurgitation Tricuspid regurgitation is also called tricuspid ... the tricuspid valve may also be needed. Tricuspid Stenosis Tricuspid stenosis is a narrowing or blockage of ...

  7. Autonomous valve for detection of biopolymer degradation

    DEFF Research Database (Denmark)

    Keller, Stephan Urs; Noeth, Nadine-Nicole; Fetz, Stefanie

    2009-01-01

    We present a polymer microvalve that allows the detection of biopolymer degradation without the need of external energy. The valve is based on a polymer container filled with a colored marker solution and closed by a thin lid. This structure is covered by a film of poly(L-lactide) and degradation...... of the biopolymer triggers the release of the color which is detected visually. The autonomous valve has potential for the fast testing of biopolymer degradation under various environmental conditions or by specific enzymes....

  8. Echocardiography of the mitral valve

    OpenAIRE

    Omran, A.S.; Arifi, A.A.; Mohamed, A.A.

    2010-01-01

    Mitral valve disease is the second most common valvular heart disease after the aortic valve worldwide. Mitral valve has historically been a structure of interest by pioneers in echocardiography. One of the earliest applications of echocardiography was in the diagnosis of valvular heart disease, particularly mitral stenosis. In this review we wish to take the reader through the structural and hemodynamic evaluation of the normal mitral valve.

  9. 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

  10. Patch testing with markers of fragrance contact allergy. Do clinical tests correspond to patients' self-reported problems?

    DEFF Research Database (Denmark)

    Johansen, J D; Andersen, T F; Veien, Niels

    1997-01-01

    The aim of the present study was to investigate the relationship between patients' own recognition of skin problems using consumer products and the results of patch testing with markers of fragrance sensitization. Eight hundred and eighty-four consecutive eczema patients, 18-69 years of age, filled...... in a questionnaire prior to patch testing with the European standard series. The questionnaire contained questions about skin symptoms from the use of scented and unscented products as well as skin reactions from contact with spices, flowers and citrus fruits that could indicate fragrance sensitivity. A highly...... significant association was found between reporting a history of visible skin symptoms from using scented products and a positive patch test to the fragrance mix, whereas no such relationship could be established to the Peru balsam in univariate or multivariate analysis. Our results suggest that the role...

  11. Mindfulness Facets, Social Anxiety, and Drinking to Cope with Social Anxiety: Testing Mediators of Drinking Problems.

    Science.gov (United States)

    Clerkin, Elise M; Sarfan, Laurel D; Parsons, E Marie; Magee, Joshua C

    2017-02-01

    This cross-sectional study tested social anxiety symptoms, trait mindfulness, and drinking to cope with social anxiety as potential predictors and/or serial mediators of drinking problems. A community-based sample of individuals with co-occurring social anxiety symptoms and alcohol dependence were recruited. Participants ( N = 105) completed measures of social anxiety, drinking to cope with social anxiety, and alcohol use and problems. As well, participants completed the Five Facet Mindfulness Questionnaire , which assesses mindfulness facets of accepting without judgment, acting with awareness, not reacting to one's internal experiences, observing and attending to experiences, and labeling and describing. As predicted, the relationship between social anxiety symptoms and drinking problems was mediated by social anxiety coping motives across each of the models. Further, the relationship between specific mindfulness facets (acting with awareness, accepting without judgment, and describe) and drinking problems was serially mediated by social anxiety symptoms and drinking to cope with social anxiety. This research builds upon existing studies that have largely been conducted with college students to evaluate potential mediators driving drinking problems. Specifically, individuals who are less able to act with awareness, accept without judgment, and describe their internal experiences may experience heightened social anxiety and drinking to cope with that anxiety, which could ultimately result in greater alcohol-related problems.

  12. 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

  13. SAFETY SHUTOFF VALVE

    DEFF Research Database (Denmark)

    2010-01-01

    resulted from collision or effusion. A static tower has been applied for the main core of this part of the valve which loses balance state under the effect of collision and bounces to the neighboring part, which results in release of the catch and blockage of the gas passing channel.......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...

  14. Edwards SAPIEN 3 valve.

    Science.gov (United States)

    Binder, Ronald K; Rodés-Cabau, Josep; Wood, David A; Webb, John G

    2012-09-01

    Building on the established success with the SAPIEN, SAPIEN XT and earlier prototypic transcatheter heart valves (THV) the newest balloon-expandable valve incorporates a number of new and enhanced features intended to reduce the risk of vascular injury, to reduce paravalvular regurgitation, and to facilitate rapid and accurate positioning and implantation. The SAPIEN 3 THV incorporates a cobalt chromium stent, bovine pericardial leaflets, and both an inner and new outer polyethylene terephthalate sealing cuff. The delivery system incorporates an active three-dimensional coaxial positioning catheter, and is compatible with a 14 Fr expandable sheath.

  15. Noncontacting valve-position indicator

    Science.gov (United States)

    Crovella, E. A.; Cummins, R. D.; Wada, J. M.

    1979-01-01

    Position of sealed valve or other movable part is indicated without penetrating housing. Flux from magnets connected to stem of hydraulic valve penetrates pressure wall and is sensed by Hall-effect transducer outside wall. When valve closes, moving stem and magnets, voltage from transducer decreases; thus, stem position is indicated without physical contact.

  16. Tricuspid valve and percutaneous approach: No longer the forgotten valve!

    Science.gov (United States)

    Bouleti, Claire; Juliard, Jean-Michel; Himbert, Dominique; Iung, Bernard; Brochet, Eric; Urena, Marina; Dilly, Marie-Pierre; Ou, Phalla; Nataf, Patrick; Vahanian, Alec

    2016-01-01

    Tricuspid valve disease is mainly represented by tricuspid regurgitation (TR), which is a predictor of poor outcome. TR is usually secondary, caused by right ventricle pressure or volume overload, the leading cause being left-sided heart valve diseases. Tricuspid surgery for severe TR is recommended during left valve surgery, and consists of either a valve replacement or, most often, a tricuspid repair with or without prosthetic annuloplasty. When TR persists or worsens after left valvular surgery, redo isolated tricuspid surgery is associated with high mortality. In addition, a sizeable proportion of patients present with tricuspid surgery deterioration over time, and need a reintervention, which is associated with high morbi-mortality rates. In this context, and given the recent major breakthrough in the percutaneous treatment of aortic and mitral valve diseases, the tricuspid valve appears an appealing challenge, although it raises specific issues. The first applications of transcatheter techniques for tricuspid valve disease were valve-in-valve and valve-in-ring implantation for degenerated bioprosthesis or ring annuloplasty. Some concerns remain regarding prosthesis sizing, rapid ventricular pacing and the best approach, but these procedures appear to be safe and effective. More recently, bicuspidization using a transcatheter approach for the treatment of native tricuspid valve has been published, in two patients. Finally, other devices are in preclinical development. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  17. Operational Experience and Consolidations for the Current Lead Control Valves of the Large Hadron Collider

    CERN Document Server

    Perin, A; Pirotte, O; Krieger, B; Widmer, A

    2012-01-01

    The Large Hadron Collider superconducting magnets are powered by more than 1400 gas cooled current leads ranging from 120 A to 13000 A. The gas flow required by the leads is controlled by solenoid proportional valves with dimensions from DN 1.8 mm to DN 10 mm. During the first months of operation, signs of premature wear were found in the active parts of the valves. This created major problems for the functioning of the current leads threatening the availability of the LHC. Following the detection of the problems, a series of measures were implemented to keep the LHC running, to launch a development program to solve the premature wear problem and to prepare for a global consolidation of the gas flow control system. This article describes first the difficulties encountered and the measures taken to ensure a continuous operation of the LHC during the first year of operation. The development of new friction free valves is then presented along with the consolidation program and the test equipment developed to val...

  18. Assessment test before the reporting phase of tutorial session in problem-based learning.

    Science.gov (United States)

    Bestetti, Reinaldo B; Couto, Lucélio B; Restini, Carolina Ba; Faria, Milton; Romão, Gustavo S

    2017-01-01

    In our context, problem-based learning is not used in the preuniversity environment. Consequently, students have a great deal of difficulty adapting to this method, particularly regarding self-study before the reporting phase of a tutorial session. Accordingly, the aim of this study was to assess if the application of an assessment test (multiple choice questions) before the reporting phase of a tutorial session would improve the academic achievement of students at the preclinical stage of our medical course. A test consisting of five multiple choice questions, prepared by tutors of the module at hand and related to the problem-solving process of each tutorial session, was applied following the self-study phase and immediately before the reporting phase of all tutorial sessions. The questions were based on the previously established student learning goals. The assessment was applied to all modules from the fifth to the eighth semesters. The final scores achieved by students in the end-of-module tests were compared. Overall, the mean test score was 65.2±0.7% before and 68.0±0.7% after the introduction of an assessment test before the reporting phase (P0.05). Students in the eighth semester scored 71.8±2.3% compared to 70±2% when they were in the seventh semester (P>0.05). In our medical course, the application of an assessment test (a multiple choice test) before the reporting phase of the problem-based learning tutorial process increases the overall academic achievement of students, especially of those in the sixth semester in comparison with when they were in the fifth semester.

  19. Mitral valve mechanics following posterior leaflet patch augmentation

    DEFF Research Database (Denmark)

    Rahmani, Azadeh; Rasmussen, Ann Qvist; Hønge, Jesper Langhoff

    2013-01-01

    Background and aim of the study: Attention towards the optimization of mitral valve repair methods is increasing. Patch augmentation is one strategy used to treat functional ischemic mitral regurgitation (FIMR). The study aim was to investigate the force balance changes in specific chordae...... tendineae emanating from the posterior papillary muscle in a FIMR-simulated valve, following posterior leaflet patch augmentation. Methods: Mitral valves were obtained from 12 pigs (body weight 80 kg). An in vitro test set-up simulating the left ventricle was used to hold the valves. The left ventricular...... pressure was regulated with water to simulate different static pressures during valve closure. A standardized oval pericardial patch (17 × 29 mm) was introduced into the posterior leaflet from mid P2 to the end of the P3 scallop. Dedicated miniature transducers were used to record the forces exerted...

  20. Joint hypermobility syndrome and mitral valve prolapse in panic disorder.

    Science.gov (United States)

    Gulpek, Demet; Bayraktar, Erhan; Akbay, Sebnem Pirildar; Capaci, Kazým; Kayikcioglu, Meral; Aliyev, Emil; Soydas, Cahide

    2004-09-01

    The purpose of this study is to test the association between joint hypermobility syndrome (JHS) and panic disorder (PD) and to determine whether mitral valve prolapse (MVP) modifies or accounts in part for the association. A total of 115 subjects are included in this study in three groups. Group I (n = 42): panic disorder patients with MVP. Group II (n = 35): panic disorder patients without mitral valve prolapse. Group III (n = 38): control subjects who had mitral valve prolapse without any psychiatric illness. Beighton criteria were used to assess joint hypermobility syndrome. Two-dimensional and M-mode echocardiography was performed on each subject to detect mitral valve prolapse. Joint hypermobility syndrome was found in 59.5% of panic disorder patients with mitral valve prolapse, in 42.9% of patients without mitral valve prolapse and in 52.6% of control subjects. Beighton scores was 4.93 +/- 2.97 in group I, 4.09 +/- 2.33 in group II, and 4.08 +/- 2.34 in group III. There was no significant difference between groups according to Beighton scores. We did not detect a statistically significant relationship between panic disorder and joint hypermobility syndrome. Mitral valve prolapse and joint hypermobility syndrome are known to be etiologically related and we suggest that mitral valve prolapse affects the prevalence of joint hypermobility syndrome in the panic disorder patients.

  1. An accurate and efficient identification of children with psychosocial problems by means of computerized adaptive testing

    Directory of Open Access Journals (Sweden)

    Reijneveld Symen A

    2011-08-01

    Full Text Available Abstract Background Questionnaires used by health services to identify children with psychosocial problems are often rather short. The psychometric properties of such short questionnaires are mostly less than needed for an accurate distinction between children with and without problems. We aimed to assess whether a short Computerized Adaptive Test (CAT can overcome the weaknesses of short written questionnaires when identifying children with psychosocial problems. Method We used a Dutch national data set obtained from parents of children invited for a routine health examination by Preventive Child Healthcare with 205 items on behavioral and emotional problems (n = 2,041, response 84%. In a random subsample we determined which items met the requirements of an Item Response Theory (IRT model to a sufficient degree. Using those items, item parameters necessary for a CAT were calculated and a cut-off point was defined. In the remaining subsample we determined the validity and efficiency of a Computerized Adaptive Test using simulation techniques, with current treatment status and a clinical score on the Total Problem Scale (TPS of the Child Behavior Checklist as criteria. Results Out of 205 items available 190 sufficiently met the criteria of the underlying IRT model. For 90% of the children a score above or below cut-off point could be determined with 95% accuracy. The mean number of items needed to achieve this was 12. Sensitivity and specificity with the TPS as a criterion were 0.89 and 0.91, respectively. Conclusion An IRT-based CAT is a very promising option for the identification of psychosocial problems in children, as it can lead to an efficient, yet high-quality identification. The results of our simulation study need to be replicated in a real-life administration of this CAT.

  2. Two self-test methods applied to an inertial system problem. [estimating gyroscope and accelerometer bias

    Science.gov (United States)

    Willsky, A. S.; Deyst, J. J.; Crawford, B. S.

    1975-01-01

    The paper describes two self-test procedures applied to the problem of estimating the biases in accelerometers and gyroscopes on an inertial platform. The first technique is the weighted sum-squared residual (WSSR) test, with which accelerator bias jumps are easily isolated, but gyro bias jumps are difficult to isolate. The WSSR method does not take full advantage of the knowledge of system dynamics. The other technique is a multiple hypothesis method developed by Buxbaum and Haddad (1969). It has the advantage of directly providing jump isolation information, but suffers from computational problems. It might be possible to use the WSSR to detect state jumps and then switch to the BH system for jump isolation and estimate compensation.

  3. Aortic valve surgery - open

    Science.gov (United States)

    ... be able to store blood in the blood bank for transfusions during and after your surgery. Ask ... Mechanical heart valves do not fail often. However, blood clots can develop on them. If a blood clot forms, you may have a stroke. Bleeding can occur, ...

  4. Permutation tests in the two-sample problem for functional data

    OpenAIRE

    Cabaña, Alejandra; Estrada, Ana Maria; Peña, Jairo I.; Quiroz, Adolfo J.

    2016-01-01

    Three different permutation test schemes are discussed and compared in the context of the two-sample problem for functional data. One of the procedures was essentially introduced by Lopez-Pintado and Romo (2009), using notions of functional data depth to adapt the ideas originally proposed by Liu and Singh (1993) for multivariate data. Of the new methods introduced here, one is also based on functional data depths, but uses a different way (inspired by Meta-Analysis) to assess the significanc...

  5. Measurement of reed valve kinematics

    Directory of Open Access Journals (Sweden)

    Fenkl Michael

    2016-01-01

    Full Text Available The measurement of key kinematic parameters of a reed valve movement is necessary for the further development of the reed valve system. These parameters are dependent on the geometry and material properties of the valve. As they directly affect the quantity of air flowing around the valve, a simple and easy to implement measurement of various valve configuration based on the air flow has been devised and is described in this paper, along with its technical parameters and drawbacks when evaluating reed valves used in reciprocating air compressors. Results are presented for a specimen of a compressor under examination. All kinematic parameters, and timing of the opening and closing of the valve, obtained from the measurement are presented and discussed.

  6. Space-time fluid mechanics computation of heart valve models

    Science.gov (United States)

    Takizawa, Kenji; Tezduyar, Tayfun E.; Buscher, Austin; Asada, Shohei

    2014-10-01

    Fluid mechanics computation of heart valves with an interface-tracking (moving-mesh) method was one of the classes of computations targeted in introducing the space-time (ST) interface tracking method with topology change (ST-TC). The ST-TC method is a new version of the Deforming-Spatial-Domain/Stabilized ST (DSD/SST) method. It can deal with an actual contact between solid surfaces in flow problems with moving interfaces, while still possessing the desirable features of interface-tracking methods, such as better resolution of the boundary layers. The DSD/SST method with effective mesh update can already handle moving-interface problems when the solid surfaces are in near contact or create near TC, if the "nearness" is sufficiently "near" for the purpose of solving the problem. That, however, is not the case in fluid mechanics of heart valves, as the solid surfaces need to be brought into an actual contact when the flow has to be completely blocked. Here we extend the ST-TC method to 3D fluid mechanics computation of heart valve models. We present computations for two models: an aortic valve with coronary arteries and a mechanical aortic valve. These computations demonstrate that the ST-TC method can bring interface-tracking accuracy to fluid mechanics of heart valves, and can do that with computational practicality.

  7. Assessment test before the reporting phase of tutorial session in problem-based learning

    Directory of Open Access Journals (Sweden)

    Bestetti RB

    2017-02-01

    Full Text Available Reinaldo B Bestetti, Lucélio B Couto, Carolina BA Restini, Milton Faria Jr, Gustavo S Romão Department of Medicine, UNAERP Medical School, University of Ribeirão Preto, Ribeirão Preto, Brazil Purpose: In our context, problem-based learning is not used in the preuniversity environment. Consequently, students have a great deal of difficulty adapting to this method, particularly regarding self-study before the reporting phase of a tutorial session. Accordingly, the aim of this study was to assess if the application of an assessment test (multiple choice questions before the reporting phase of a tutorial session would improve the academic achievement of students at the preclinical stage of our medical course.Methods: A test consisting of five multiple choice questions, prepared by tutors of the module at hand and related to the problem-solving process of each tutorial session, was applied following the self-study phase and immediately before the reporting phase of all tutorial sessions. The questions were based on the previously established student learning goals. The assessment was applied to all modules from the fifth to the eighth semesters. The final scores achieved by students in the end-of-module tests were compared.Results: Overall, the mean test score was 65.2±0.7% before and 68.0±0.7% after the introduction of an assessment test before the reporting phase (P<0.05. Students in the sixth semester scored 67.6±1.6% compared to 63.9±2.2% when they were in the fifth semester (P<0.05. Students in the seventh semester achieved a similar score to their sixth semester score (64.6±2.6% vs 63.3±2%, respectively, P>0.05. Students in the eighth semester scored 71.8±2.3% compared to 70±2% when they were in the seventh semester (P>0.05.Conclusion: In our medical course, the application of an assessment test (a multiple choice test before the reporting phase of the problem-based learning tutorial process increases the overall academic

  8. Micro-valve pump light valve display

    Science.gov (United States)

    Lee, Yee-Chun

    1993-01-01

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

  9. Research on magnetorheological damper suspension with permanent magnet and magnetic valve based on developed FOA-optimal control algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Ping; Gao, Hong [Anhui Polytechnic University, Wuhu (China); Niu, Limin [Anhui University of Technology, Maanshan (China)

    2017-07-15

    Due to the fail safe problem, it was difficult for the existing Magnetorheological damper (MD) to be widely applied in automotive suspensions. Therefore, permanent magnets and magnetic valves were introduced to existing MDs so that fail safe problem could be solved by the magnets and damping force could be adjusted easily by the magnetic valve. Thus, a new Magnetorheological damper with permanent magnet and magnetic valve (MDPMMV) was developed and MDPMMV suspension was studied. First of all, mechanical structure of existing magnetorheological damper applied in automobile suspensions was redesigned, comprising a permanent magnet and a magnetic valve. In addition, prediction model of damping force was built based on electromagnetics theory and Bingham model. Experimental research was onducted on the newly designed damper and goodness of fit between experiment results and simulated ones by models was high. On this basis, a quarter suspension model was built. Then, fruit Fly optimization algorithm (FOA)-optimal control algorithm suitable for automobile suspension was designed based on developing normal FOA. Finally, simulation experiments and bench tests with input surface of pulse road and B road were carried out and the results indicated that working erformance of MDPMMV suspension based on FOA-optimal control algorithm was good.

  10. [History, present and future of biomaterials used for artificial heart valves].

    Science.gov (United States)

    Kostrzewa, Benita; Rybak, Zbigniew

    2013-01-01

    Artificial heart valves can be classified into mechanical and biological. We have three types of mechanical heart valves: caged ball, tilting disc and bileaflet. Mechanical heart valves are made from various materials. They may be produced from metals, ceramics and polymers, e.g.: stainless steel, titanium, silicone, pyrolytic carbon. Biological valves are made from synthetic components (e.g.: PTFE, Dacron) and materials of biological origin (e.g.: cow pericardium, pig heart valve). We have also identified transcatheter aortic valve implantation (TAVI). TAVI may be produced from metals, ceramics and polymers (e.g.: stainless steel, titanium, Dacron) and biological material (e.g.: pig heart valve). This paper describes advantages and disadvantages of different types of artificial heart valves. The lifespan of mechanical valves is 20-30 years and they can be used for patients of any age. Mechanical valves have also disadvantages--anticoagulants are required to prevent thrombosis. Biological valves are made from natural materials, so they do not require prolonged anticoagulation. Their lifetime is 10-15 years, so they are offered to patients over 40 years. Another problem is the occurrence of calcification.

  11. Valve Concepts for Microfluidic Cell Handling

    Directory of Open Access Journals (Sweden)

    M. Grabowski

    2010-01-01

    Full Text Available In this paper we present various pneumatically actuated microfluidic valves to enable user-defined fluid management within a microfluidic chip. To identify a feasible valve design, certain valve concepts are simulated in ANSYS to investigate the pressure dependent opening and closing characteristics of each design. The results are verified in a series of tests. Both the microfluidic layer and the pneumatic layer are realized by means of soft-lithographic techniques. In this way, a network of channels is fabricated in photoresist as a molding master. By casting these masters with PDMS (polydimethylsiloxane we get polymeric replicas containing the channel network. After a plasma-enhanced bonding process, the two layers are irreversibly bonded to each other. The bonding is tight for pressures up to 2 bar. The valves are integrated into a microfluidic cell handling system that is designed to manipulate cells in the presence of a liquid reagent (e.g. PEG – polyethylene glycol, for cell fusion. For this purpose a user-defined fluid management system is developed. The first test series with human cell lines show that the microfluidic chip is suitable for accumulating cells within a reaction chamber, where they can be flushed by a liquid medium.

  12. Exact and conceptual repetition dissociate conceptual memory tests: problems for transfer appropriate processing theory.

    Science.gov (United States)

    McDermott, K B; Roediger, H L

    1996-03-01

    Three experiments examined whether a conceptual implicit memory test (specifically, category instance generation) would exhibit repetition effects similar to those found in free recall. The transfer appropriate processing account of dissociations among memory tests led us to predict that the tests would show parallel effects; this prediction was based upon the theory's assumption that conceptual tests will behave similarly as a function of various independent variables. In Experiment 1, conceptual repetition (i.e., following a target word [e.g., puzzles] with an associate [e.g., jigsaw]) did not enhance priming on the instance generation test relative to the condition of simply presenting the target word once, although this manipulation did affect free recall. In Experiment 2, conceptual repetition was achieved by following a picture with its corresponding word (or vice versa). In this case, there was an effect of conceptual repetition on free recall but no reliable effect on category instance generation or category cued recall. In addition, we obtained a picture superiority effect in free recall but not in category instance generation. In the third experiment, when the same study sequence was used as in Experiment 1, but with instructions that encouraged relational processing, priming on the category instance generation task was enhanced by conceptual repetition. Results demonstrate that conceptual memory tests can be dissociated and present problems for Roediger's (1990) transfer appropriate processing account of dissociations between explicit and implicit tests.

  13. Maintenance guide for air-operated valves, pneumatic actuators, and accessories

    Energy Technology Data Exchange (ETDEWEB)

    Preckwinkle, S.E. (Fossil Technologies, Inc., Kelso, WA (United States))

    1992-07-01

    Air Operated Valves (AOVs) are used extensively in the power generation industry for process control and system isolation functions. Their proper operation is essential to reliable power plant operation. This guide discusses major components such as actuators, valves, and positioners, and explains the inter-relationship of these components. Diagrams indicating the application and operation of various types of actuators are presented as an aid for thorough investigation of malfunctioning equipment. Recent developments on diagnostic equipment for AOVs are covered and valve traces on valves with maintenance related problems are used to demonstrate how the diagnostic equipment can quickly solve complex valve problems. In addition, predictive and preventive maintenance recommendations based on specific failure data are included. The guide also includes a troubleshooting section with tables providing easily accessible information to minimize troubleshooting costs. Appendices augment the guide by providing a glossary of terms and various engineering schedules including useful engineering parameters for the proper maintenance of air operated valves and accessories.

  14. Multi-objective global optimization of a butterfly valve using genetic algorithms.

    Science.gov (United States)

    Corbera, Sergio; Olazagoitia, José Luis; Lozano, José Antonio

    2016-07-01

    A butterfly valve is a type of valve typically used for isolating or regulating flow where the closing mechanism takes the form of a disc. For a long time, the attention of many researchers has focused on carrying out structural (FEM) and computational fluid dynamics (CFD) analysis in order to increase the performance of this type of flow-control device. This paper proposes a novel multi-objective approach for the design optimization of a butterfly valve using advanced genetic algorithms based on Pareto dominance. Firstly, after defining the need for this study and analyzing previous papers on the subject, the initial butterfly valve is presented and the initial fluid and structural analysis are carried out. Secondly, the optimization problem is defined and the optimization strategy is presented. The design variables are identified and a parameterization model of the valve is made. Thirdly, initial design candidates are generated by DOE and design optimization using genetic algorithms is performed. In this part of the process structural and CFD analysis are calculated for each candidate simultaneously. The optimization process involves various types of software and Python scripts are needed for their interaction and the connection of all steps. Finally, a set of optimal solutions is obtained and the optimum design that provides a 65.4% stress reduction, a 5% mass reduction and a 11.3% flow increase is selected in accordance with manufacturer preferences. Validation of the results is provided by comparing experimental test results with the values obtained for the initial design. The results demonstrate the capability and potential of the proposed methodology. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  15. In vitro and in vivo evaluation of a jellyfish valve for practical use.

    Science.gov (United States)

    Imachi, K; Mabuchi, K; Chinzei, T; Abe, Y; Imanishi, K; Yonezawa, T; Maeda, K; Suzukawa, M; Kouno, A; Ono, T

    1989-01-01

    A practical model (Model-1) of a jellyfish valve was developed, which was composed of a valve seat and a flexible membrane. The valve seat has 12 spokes to hold the membrane, and is made of solution-cast polyurethane coated with segmented polyurethane or Cardiothane. The flexible membrane is 200 microns thick, and made of segmented polyurethane or Cardiothane by a casting method. The valves were built into a sac type blood pump. In mock circulation tests, this jellyfish valve revealed performance superior to Bjork-Shiley (B-S) valves. No stagnation point was observed in the flow visualization study, and durability testing is ongoing beyond 7.5 months. The valves were used in animal artificial heart experiments for up to 112 days with good performance. No thrombi were formed on the valve membrane or around the spokes. Although a ring thrombus was observed behind the valve, it would be prevented by perfect adhesion of the valve seat to the blood pump. The plasma free hemoglobin level was less than 2 mg/dl during these experiments. These results suggest that a jellyfish valve (Model-1) is useful in ventricular assist devices, and in short-term bridge use of a total artificial heart.

  16. Improvement of a Pneumatic Control Valve with Self-Holding Function

    Science.gov (United States)

    Dohta, Shujiro; Akagi, Tetsuya; Kobayashi, Wataru; Shimooka, So; Masago, Yusuke

    2017-10-01

    The purpose of this study is to develop a small-sized, lightweight and low-cost control valve with low energy consumption and to apply it to the assistive system. We have developed some control valves; a tiny on/off valve using a vibration motor, and an on/off valve with self-holding function. We have also proposed and tested the digital servo valve with self-holding function using permanent magnets and a small-sized servo motor. In this paper, in order to improve the valve, an analytical model of the digital servo valve is proposed. And the simulated results by using the analytical model and identified parameters were compared with the experimental results. Then, the improved digital servo valve was designed based on the calculated results and tested. As a result, we realized the digital servo valve that can control the flow rate more precisely while maintaining its volume and weight compared with the previous valve. As an application of the improved valve, a position control system of rubber artificial muscle was built and the position control was performed successfully.

  17. First Reported Successful Femoral Valve-in-Valve Transcatheter Aortic Valve Replacement Using the Edwards Sapien 3 Valve.

    Science.gov (United States)

    Fournier, Stephane; Monney, Pierre; Roguelov, Christan; Zuffi, Andrea; Iglesias, Juan F; Qanadli, Salah D; Courbon, Cecile; Eeckhout, Eric; Muller, Olivier

    2015-10-01

    Management of degenerated aortic valve bioprosthesis classically requires redo surgery, but transcatheter aortic valve-in-valve implantation is becoming a valid alternative in selected cases. In the case of a degenerated Mitroflow bioprosthesis, TAVR is associated with an additional challenge due to a specific risk of coronary occlusion. We aimed to assess the safety and feasibility of transfemoral valve-in-valve implantation of the new Edwards Sapien 3 (Edwards Lifesciences) in a degenerated Mitroflow bioprosthesis (Sorin Group, Inc). We report here the safety and feasibility of transfemoral valve-in-valve implantation of a 23 mm Edwards Sapien 3 in a degenerated 25 mm Mitroflow valve and describe the specific assessment of the risk of coronary obstruction using a multi-imaging modality. The final result showed an absence of aortic regurgitation and a mean transvalvular gradient of 14 mm Hg. The patient had no major adverse cardiovascular events at 30-day follow-up. Transcatheter valve-in-valve implantation of an Edwards Sapien 3 in a degenerated Mitroflow is feasible and safe, considering a careful assessment of the risk of coronary obstruction with Mitroflow bioprosthesis due to leaflets mounted externally to the stent.

  18. Mechanical Valve Replacement: Early Results

    Directory of Open Access Journals (Sweden)

    Habib Cakir

    2012-02-01

    Full Text Available Aim: Valve diseases in developing countries like Turkey which often occur as a complication of rheumatic fever are a serious disease. Surgical treatment of valve diseases should be done before irreversible damage to the myocardium occurred. In this study, we aimed to present the early results of mechanical valve replacement operations. Method: A hundred patients with mechanical valve replacement surgery were retrospectively evaluated in Seyhan Application Center attached to our clinic between July 2007 and August 2011. Results: Fifty patients were male and 50 were women. The mean age of patients was 47.88 (18-78. Isolated aortic valve replacement (AVR was performed to 23 patients, isolated mitral valve replacement (MVR was 32, double valve replacement (AVR + MVR was 12, MVR + aortic valve valvuloplasty was 1, AVR + mitral kommissurotomi was 1, AVR + coronary artery bypass graft surgery (CABG was 17, MVR + CABG was 8, MVR + atrial septal defect closure was 2 and Bentall procedure.was 4 patients. In addition, ablation procedure was performed to 5 patients intraoperatively because of preoperative atrial fibrillation. Two patients (2 % died in early postoperative period. Conclusion: Mechanical prosthetic valves are used for surgical treatment of valve disease with low mortality and morbidity in a large group of patients like women that not to think to get pregnant, non advanced age group and patients have less risky for anticoagulation drug in our clinic. [Cukurova Med J 2012; 37(1.000: 49-54

  19. Transcatheter aortic valve implantation in failed bioprosthetic surgical valves

    DEFF Research Database (Denmark)

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

    2014-01-01

    IMPORTANCE: Owing to a considerable shift toward bioprosthesis implantation rather than mechanical valves, it is expected that patients will increasingly present with degenerated bioprostheses in the next few years. Transcatheter aortic valve-in-valve implantation is a less invasive approach......, 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...

  20. TESTING OF NUMERICAL SOLUTION OF THE PROBLEM OF DETERMINING SOURCES OF MAGNETOSTATIC FIELD IN MAGNETIZED MEDIUM

    Directory of Open Access Journals (Sweden)

    V. M. Mikhailov

    2017-12-01

    Full Text Available Purpose. Testing of numerical solution algorithm for integral equation for calculation of plane meridian magnetostatic field source distribution at interfaces of piecewise homogeneous magnetized medium by means of electrostatic analogy. Methodology. The piecewise homogeneous medium consists of three regions with different magnetic permeabilities: the shell of arbitrary meridian section, external unlimited medium outside the shell, and the medium inside the shell. For testing external homogeneous magnetic field effect on spherical shell is considered. The analytical solution of this problem on the basis of electrostatic analogy from the solution of the problem uniform electrostatic field effect on dielectric shell is obtained. We have compared results of numerical solution of integral equation with the data obtained by means of analytical solution at the variation of magnetic permeabilities of regions of medium. Results. Integral equation and the algorithm of its numerical solution for calculation of source field distribution at the boundaries of piecewise homogeneous medium is validated. Testing of integral equations correctness for calculation of fictitious magnetic charges distribution on axisymmetric boundaries of piecewise homogeneous magnetized medium and algorithms of their numerical solutions can be carried out by means of analytical solutions of problems of homogeneous electrostatic field effect analysis on piecewise homogeneous dielectric medium with central symmetry of boundaries – single-layer and multilayer spherical shells. In the case of spherical shell in wide range of values of the parameter λk, including close to ± 1, numerical solution of integral equation is stable, and relative error in calculating of fictitious magnetic charges surface density and magnetic field intensity inside the shell is from tenths of a percent up to several percent except for the cases of very small values of these quantities. Originality. The use

  1. Runflat Testing

    Science.gov (United States)

    2015-09-09

    the valve cores using a valve core removal tool to simulate a puncture flat. This should be done at the test site, after the tires are warmed up...F), and ideally be as close to the SAE standard temperature of 25 °C (77 °F) as possible. Test conditions should also be dry (no precipitation or

  2. Performance Characteristics of an Isothermal Freeze Valve

    Energy Technology Data Exchange (ETDEWEB)

    Hailey, A.E.

    2001-08-22

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

  3. Tricuspid Valve Replacement, Mechnical vs. Biological Valve, Which Is Better?

    Directory of Open Access Journals (Sweden)

    Haitham Akram Altaani

    2013-06-01

    Full Text Available Background: The initial trial in tricuspid surgery is repair; however, replacement is done whenever the valve is badly diseased. Tricuspid valve replacement comprises 1.7% of all tricuspid valve surgeries. Materials and Methods: The present retrospective study was performed using the medical records of 21 cases who underwent tricuspid valve replacement from January 2002 until the end of December 2010. The mean age of the participants was 52.3±8.8 years and 66.7% were females. In addition, tricuspid valve replacement was associated with mitral valve surgery, aortic valve surgery, and both in 14.3%, 4.8%, and 33.3% of the cases, respectively. Yet, isolated tricuspid valve replacement and redo surgery were performed in 10 cases (47.6% and 8 cases (38.1%, respectively. Besides, trial of repair was done in 14 cases (66.7%. Moreover, biological and mechanical valves were used in 76.2% and 23.8% of the patients, respectively. Results: According to the results, early mortality was 23.8% and one year survival was 66.7%. Moreover, early mortality was caused by right ventricular failure, multiorgan failure, medistinitis, and intracerbral bleeding in 42%, 28.6%, 14.3%, and 14.3% of the cases, respectively. In addition, 57.1% of the deaths had occurred in the cases where the biological valve was used, while 42.9% of the deaths had taken place where the mechanical one was utilized. Conclusions: The patients who require tricuspid valve replacement are usually high risk surgical candidates with early and long term mortality. The findings of the current study showed no significant hemodynamic difference between mechanical and biological valves.

  4. Thermo-electric valve

    Science.gov (United States)

    Chamberland, R. R.; Stanland, A. J.

    1985-02-01

    A thermo-electric valve is described for scuttling floating devices comprising, a cylindrical sleeve affixed to and passing through a bulkhead separating a pressurized medium on one side from a lower pressure space on the other side, a piston moveably mounted within the sleeve bore and exposed to the pressurized medium having a portion thereof blocking the sleeve bore, an O-ring sealing the gap between the piston head and the sleeve bore, a fully compressed spring pressing against the piston, a rigid dielectric washer and a low power resistor holding the piston against the spring. In operation a low current is passed through the resistor, disintegrating it and releasing the spring's stored energy. This actuates the valve by expelling the piston which allows the pressurized fluid or gas to enter the lower pressure space.

  5. PARAMETER ESTIMATION OF VALVE STICTION USING ANT COLONY OPTIMIZATION

    Directory of Open Access Journals (Sweden)

    S. Kalaivani

    2012-07-01

    Full Text Available In this paper, a procedure for quantifying valve stiction in control loops based on ant colony optimization has been proposed. Pneumatic control valves are widely used in the process industry. The control valve contains non-linearities such as stiction, backlash, and deadband that in turn cause oscillations in the process output. Stiction is one of the long-standing problems and it is the most severe problem in the control valves. Thus the measurement data from an oscillating control loop can be used as a possible diagnostic signal to provide an estimate of the stiction magnitude. Quantification of control valve stiction is still a challenging issue. Prior to doing stiction detection and quantification, it is necessary to choose a suitable model structure to describe control-valve stiction. To understand the stiction phenomenon, the Stenman model is used. Ant Colony Optimization (ACO, an intelligent swarm algorithm, proves effective in various fields. The ACO algorithm is inspired from the natural trail following behaviour of ants. The parameters of the Stenman model are estimated using ant colony optimization, from the input-output data by minimizing the error between the actual stiction model output and the simulated stiction model output. Using ant colony optimization, Stenman model with known nonlinear structure and unknown parameters can be estimated.

  6. Perceval S aortic valve implantation in an achondroplastic Dwarf

    Directory of Open Access Journals (Sweden)

    Nikolaos G Baikoussis

    2016-01-01

    Full Text Available Despite cardiovascular disease in patients with dwarfism is not rare; there is a lack of reports referring to cardiac interventions in such patients. Dwarfism may be due to achondroplasia or hormonal growth disorders. We present a 58-year-old woman with episodes of dyspnea for several months. She underwent on transthoracic echocardiography, and she diagnosed with severe aortic valve stenosis. She referred to our department for surgical treatment of this finding. In accordance of her anthropometric characteristics and her very small aortic annulus, we had the dilemma of prosthesis selection. We decided to implant a stentless valve to optimize her effective orifice area. Our aim is to present the successful Perceval S valve implantation and the descriptions of the problems coming across in operating on these special patients. To our knowledge, this is the first case patient in which a Perceval S valve is implanted according to the international bibliography.

  7. Patents and heart valve surgery--I: mechanical valves.

    Science.gov (United States)

    Cheema, Faisal H; Hussain, Nasir; Kossar, Alexander P; Polvani, Gianluca

    2013-04-01

    Valvular heart disease, inherited or acquired, affects more than 5 million Americans yearly. Whereas medical treatment is beneficial in the initial stages of valvular heart disease, surgical correction provides symptomatic relief and long-term survival benefits. Surgical options include either repair or replacement using mechanical or bio-prosthetic valves. Patient age and the post-operative need for anticoagulation therapy are major determinants of the choice between use of mechanical or bio-prosthetic valves. Since the first mechanical valves were made available several decades ago, the incorporation of increasingly sophisticated materials and methodologies has led to substantial improvements in the valve design, and has catalyzed a parallel increase in the amount of patents issued for these emerging technologies. In this paper, we have chronologically reviewed such patents, briefly discussed various challenges that mechanical heart valve implementation is faced with and finally reviewed some of the strategies employed to overcome such obstacles. An ideal prosthetic heart valve would comprehensively mimic the natural hemodynamics and physiology of the native heart valve. Additionally, such a valve would be easily implantable, associated with a minimal risk of thrombosis and thus need for anti-coagulation, and with a proven long-term durability. With cutting edge technological advancements in the recent times, the ongoing innovative and collaborative efforts of physicians, scientists, and engineers will not seize until an ideal mechanical heart valve becomes a reality.

  8. Aortic valve replacement

    DEFF Research Database (Denmark)

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

    2008-01-01

    countries. METHODS: A multi-institutional, non-randomized, retrospective analysis was conducted among 2,932 patients who underwent AVR surgery at seven tertiary cardiac surgery centers throughout Europe. Demographic and perioperative variables including valve size and type, body surface area (BSA) and early...... and southern European countries. Imbalances in the prevalence of rheumatic heart disease, health resource availability and variations in surgical practice throughout Europe might be possible etiological causes....

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

    Science.gov (United States)

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

    1981-01-01

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

  10. Fuzzy Pattern Classification Based Detection of Faulty Electronic Fuel Control (EFC Valves Used in Diesel Engines

    Directory of Open Access Journals (Sweden)

    Umut Tugsal

    2014-05-01

    Full Text Available In this paper, we develop mathematical models of a rotary Electronic Fuel Control (EFC valve used in a Diesel engine based on dynamic performance test data and system identification methodology in order to detect the faulty EFC valves. The model takes into account the dynamics of the electrical and mechanical portions of the EFC valves. A recursive least squares (RLS type system identification methodology has been utilized to determine the transfer functions of the different types of EFC valves that were investigated in this study. Both in frequency domain and time domain methods have been utilized for this purpose. Based on the characteristic patterns exhibited by the EFC valves, a fuzzy logic based pattern classification method was utilized to evaluate the residuals and identify faulty EFC valves from good ones. The developed methodology has been shown to provide robust diagnostics for a wide range of EFC valves.

  11. Childhood family instability and mental ealth problems during late adolescence : a test of two mediation models-The TRAILS Study

    NARCIS (Netherlands)

    Bakker, Martin P.; Ormel, Johan; Verhulst, Frank C.; Oldehinkel, Albertine J.

    2012-01-01

    This study tested whether childhood family instability is associated with mental health problems during adolescence through continued family instability and/or through a preadolescent onset of mental health problems. This test use data from a prospective population cohort of 2,230 Dutch adolescents

  12. Childhood Family Instability and Mental Health Problems during Late Adolescence: A Test of Two Mediation Models--The TRAILS Study

    Science.gov (United States)

    Bakker, Martin P.; Ormel, Johan; Verhulst, Frank C.; Oldehinkel, Albertine J.

    2012-01-01

    This study tested whether childhood family instability is associated with mental health problems during adolescence through continued family instability and/or through a preadolescent onset of mental health problems. This test use data from a prospective population cohort of 2,230 Dutch adolescents ("M" age = 11.09, "SD" = 0.56…

  13. 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.

  14. Benchmark problems of start-up core physics of High Temperature Engineering Test Reactor (HTTR)

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, Kiyonobu; Nojiri, Naoki; Fujimoto, Nozomu; Nakano, Masaaki; Ando, Hiroei; Nagao, Yoshiharu; Nagaya, Yasunobu; Akino, Fujiyosi; Takeuchi, Mituo; Fujisaki, Shingo; Shiozawa, Shusaku [Japan Atomic Energy Research Institute JAERI, Ibaraki-ken (Japan)

    1998-09-01

    The experimental data of the HTTRs start-up core physics are useful to verify design codes of commercial HTGRs due to the similarities in the core size and excess reactivity. Form these viewpoints, it is significant to carry out the bench mark tests of design codes by using data of start-up core physics experiments planned for the HTTR. The evaluations of the first criticality, excess reactivity of annular cores, etc., are proposed for the benchmark problem. It was found from our precalculations that diffusion calculations provide larger excess reactivity and small number of fuel columns for the first criticality than Monte Carlo calculations. 19 refs.

  15. New Tools to Prepare ACE Cross-section Files for MCNP Analytic Test Problems

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Monte Carlo Codes Group

    2016-06-17

    Monte Carlo calculations using one-group cross sections, multigroup cross sections, or simple continuous energy cross sections are often used to: (1) verify production codes against known analytical solutions, (2) verify new methods and algorithms that do not involve detailed collision physics, (3) compare Monte Carlo calculation methods with deterministic methods, and (4) teach fundamentals to students. In this work we describe 2 new tools for preparing the ACE cross-section files to be used by MCNP® for these analytic test problems, simple_ace.pl and simple_ace_mg.pl.

  16. Optothermally actuated capillary burst valve

    Science.gov (United States)

    Eriksen, Johan; Bilenberg, Brian; Kristensen, Anders; Marie, Rodolphe

    2017-04-01

    We demonstrate the optothermal actuation of individual capillary burst valves in an all-polymer microfluidic device. The capillary burst valves are realised in a planar design by introducing a fluidic constriction in a microfluidic channel of constant depth. We show that a capillary burst valve can 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. 10, 826-832 (2010)]. An individual valve is burst by focusing the laser in its vicinity. We demonstrate the capture of single polystyrene 7 μm beads in the constriction triggered by the bursting of the valve.

  17. Update of transcatheter valve treatment.

    Science.gov (United States)

    Liu, Xian-bao; Wang, Jian-an

    2013-08-01

    Transcatheter valve implantation or repair has been a very promising approach for the treatment of valvular heart diseases since transcatheter aortic valve implantation (TAVI) was successfully performed in 2002. Great achievements have been made in this field (especially TAVI and transcatheter mitral valve repair--MitraClip system) in recent years. Evidence from clinical trials or registry studies has proved that transcatheter valve treatment for valvular heart diseases is safe and effective in surgical high-risk or inoperable patients. As the evidence accumulates, transcatheter valve treatment might be an alterative surgery for younger patients with surgically low or intermediate risk valvular heart diseases in the near future. In this paper, the updates on transcatheter valve treatment are reviewed.

  18. Identifying cognitive problems in children and adolescents with depression using computerized neuropsychological testing.

    Science.gov (United States)

    Brooks, Brian L; Iverson, Grant L; Sherman, Elisabeth M S; Roberge, Marie-Claude

    2010-01-01

    Depression in children and adolescents can negatively impact cognitive functioning, social development, and academic performance. The purpose of this study was to determine whether a computerized battery of neuropsychological tests could detect neurocognitive difficulties in children and adolescents with depression. Participants included 30 children and adolescents between the ages of 9 and 17 years (M = 14.6, SD = 2.1) with a clinical diagnosis of depression. Healthy control participants were individually matched on age, education, sex, race, primary language, handedness, and self-reported computer familiarity. All participants completed the Central Nervous System Vital Signs computerized battery. This battery of seven tests yields 23 test scores and 5 domain scores (Memory, Psychomotor Speed, Reaction Time, Complex Attention, and Cognitive Flexibility). Children and adolescents with depression performed worse on the Memory (Cohen's d = .43) and Complex Attention domains (d = .58) than matched controls. On the individual test scores, children and adolescents with depression performed worse on delayed verbal memory (d = .63), delayed visual memory (d = .34), measures of reaction time (d = .34-.53), and accuracy/inhibition on complex attention tasks (d = .49-.65). When considering the five domain scores simultaneously, children and adolescents with depression were more likely to have two or more scores at or below the 5th percentile (p = .05). Children and adolescents with depression have problems with reduced processing speed, memory for verbal information, and executive functioning on this computerized battery of tests, which represents a feasible method for neuropsychological screening.

  19. SULIVAN: Remote Manual Valve Monitoring System Real-Time Transmission of Valve Positions to Reduce Alignment Errors

    Energy Technology Data Exchange (ETDEWEB)

    Denis, J.C.; Mace, J.R.; Perisse, J.

    2015-07-01

    Every year, a number of plants worldwide face valve misalignment issues that can lead to damaged components and unplanned extended outage. By installing valve monitoring solutions, the plant can expect a reduction of the risk of valve misalignment events. Over the past years, AREVA has developed Wireless communication solutions and Smart sensor expertise at its own facilities and has carried out tests in nuclear power plants. This paper presents AREVA Wireless studies and Solutions that could be implemented in a nuclear plant. These solutions are mainly based on IoT technologies as MEMs and Low Power Wide Area Network, LPWAN. (Author)

  20. Mitral valve repair versus replacement

    Science.gov (United States)

    Keshavamurthy, Suresh; Gillinov, A. Marc

    2015-01-01

    Degenerative, ischemic, rheumatic and infectious (endocarditis) processes are responsible for mitral valve disease in adults. Mitral valve repair has been widely regarded as the optimal surgical procedure to treat mitral valve dysfunction of all etiologies. The supporting evidence for repair over replacement is strongest in degenerative mitral regurgitation. The aim of the present review is to summarize the data in each category of mitral insufficiency and to provide recommendations based upon this data. PMID:26309824

  1. Supercritical carbon dioxide-based sterilization of decellularized heart valves.

    Science.gov (United States)

    Hennessy, Ryan S; Jana, Soumen; Tefft, Brandon J; Helder, Meghana R; Young, Melissa D; Hennessy, Rebecca R; Stoyles, Nicholas J; Lerman, Amir

    2017-02-01

    The goal of this research project encompasses finding the most efficient and effective method of decellularized tissue sterilization. Aortic tissue grafts have been utilized to repair damaged or diseased valves. Although, the tissues for grafting are collected aseptically, it does not eradicate the risk of contamination nor disease transfer. Thus, sterilization of grafts is mandatory. Several techniques have been applied to sterilize grafts; however, each technique shows drawbacks. In this study, we compared several sterilization techniques: supercritical carbon dioxide, electrolyzed water, gamma radiation, ethanol-peracetic acid, and hydrogen peroxide for impact on the sterility and mechanical integrity of porcine decellularized aortic valves. Valve sterility was characterized by histology, microbe culture, and electron microscopy. Uniaxial tensile testing was conducted on the valve cusps along their circumferential orientation to study these sterilization techniques on their integrity. Ethanol-peracetic acid and supercritical carbon dioxide treated valves were found to be sterile. The tensile strength of supercritical carbon dioxide treated valves (4.28 ± 0.22 MPa) was higher to those valves treated with electrolyzed water, gamma radiation, ethanol-peracetic acid and hydrogen peroxide (1.02 ± 0.15, 1.25 ± 0.25, 3.53 ± 0.41 and 0.37 ± 0.04 MPa, respectively). Superior sterility and integrity were found in the decellularized porcine aortic valves with supercritical carbon dioxide sterilization. This sterilization technique may hold promise for other decellularized soft tissues. Sterilization of grafts is essential. Supercritical carbon dioxide, electrolyzed water, gamma radiation, ethanol-peracetic acid, and hydrogen peroxide techniques were compared for impact on sterility and mechanical integrity of porcine decellularized aortic valves. Ethanol-peracetic acid and supercritical carbon dioxide treated valves were found to be sterile using histology, microbe

  2. Hard hardfacing by welding in the manufacture of valves; Problem Cobalt, alternatives, advantages, disadvantages; Recargues Duros por Soldadura en la Fabricacion de Valvulas ; el Problema del Cobalto, alternativas, ventajas, inconvenientes

    Energy Technology Data Exchange (ETDEWEB)

    Piquer Caballero, J.

    2014-07-01

    Alloys of recharge usually used in the field of the valves are base alloys cobalt (stellite), but in the field of nuclear power plants, due to radioactive activation of the cobalt, there is a growing trend to replace these alloys with other calls cobalt free . In this paper we will explore the most frequent and will be deducted the relevant advantages and disadvantages of these, in comparison with base alloys cobalt. (Author)

  3. Chaotic Multiobjective Evolutionary Algorithm Based on Decomposition for Test Task Scheduling Problem

    Directory of Open Access Journals (Sweden)

    Hui Lu

    2014-01-01

    Full Text Available Test task scheduling problem (TTSP is a complex optimization problem and has many local optima. In this paper, a hybrid chaotic multiobjective evolutionary algorithm based on decomposition (CMOEA/D is presented to avoid becoming trapped in local optima and to obtain high quality solutions. First, we propose an improving integrated encoding scheme (IES to increase the efficiency. Then ten chaotic maps are applied into the multiobjective evolutionary algorithm based on decomposition (MOEA/D in three phases, that is, initial population and crossover and mutation operators. To identify a good approach for hybrid MOEA/D and chaos and indicate the effectiveness of the improving IES several experiments are performed. The Pareto front and the statistical results demonstrate that different chaotic maps in different phases have different effects for solving the TTSP especially the circle map and ICMIC map. The similarity degree of distribution between chaotic maps and the problem is a very essential factor for the application of chaotic maps. In addition, the experiments of comparisons of CMOEA/D and variable neighborhood MOEA/D (VNM indicate that our algorithm has the best performance in solving the TTSP.

  4. Ball valve design for solid withdrawal service in coal liquefaction

    Science.gov (United States)

    Patton, Alexander J.

    1981-02-01

    Valves used for drawdown of the solids produced in the coal liquefaction process must be designed to operate at high temperatures and must prevent the buildup of solids within the valve internals to insure operability. Consideration must also be given to materials used for seating surfaces in terms of being able to withstand abrasion. Research into the design and materials for this application results in a new ball valve design with a special inlet port liner and O-ring seal. A prototype valve was built and put in service in a small scale, experimental coal liquefaction plant. For comparative purposes a standard design valve was also used, with both valves being subjected to over 1000 open/close cycles, after which both valves were removed, tested, and disassembled for inspection. The results of this experimental program will be presented, including process parameters, service conditions, and material evaluation. Particular emphasis will be placed on wear of seating surfaces and the effects of process material on the physical properties of seal and packing materials.

  5. Verification of cardiac mechanics software: benchmark problems and solutions for testing active and passive material behaviour.

    Science.gov (United States)

    Land, Sander; Gurev, Viatcheslav; Arens, Sander; Augustin, Christoph M; Baron, Lukas; Blake, Robert; Bradley, Chris; Castro, Sebastian; Crozier, Andrew; Favino, Marco; Fastl, Thomas E; Fritz, Thomas; Gao, Hao; Gizzi, Alessio; Griffith, Boyce E; Hurtado, Daniel E; Krause, Rolf; Luo, Xiaoyu; Nash, Martyn P; Pezzuto, Simone; Plank, Gernot; Rossi, Simone; Ruprecht, Daniel; Seemann, Gunnar; Smith, Nicolas P; Sundnes, Joakim; Rice, J Jeremy; Trayanova, Natalia; Wang, Dafang; Jenny Wang, Zhinuo; Niederer, Steven A

    2015-12-08

    Models of cardiac mechanics are increasingly used to investigate cardiac physiology. These models are characterized by a high level of complexity, including the particular anisotropic material properties of biological tissue and the actively contracting material. A large number of independent simulation codes have been developed, but a consistent way of verifying the accuracy and replicability of simulations is lacking. To aid in the verification of current and future cardiac mechanics solvers, this study provides three benchmark problems for cardiac mechanics. These benchmark problems test the ability to accurately simulate pressure-type forces that depend on the deformed objects geometry, anisotropic and spatially varying material properties similar to those seen in the left ventricle and active contractile forces. The benchmark was solved by 11 different groups to generate consensus solutions, with typical differences in higher-resolution solutions at approximately 0.5%, and consistent results between linear, quadratic and cubic finite elements as well as different approaches to simulating incompressible materials. Online tools and solutions are made available to allow these tests to be effectively used in verification of future cardiac mechanics software.

  6. Discrete Element Method and its application to materials failure problem on the example of Brazilian Test

    Science.gov (United States)

    Klejment, Piotr; Kosmala, Alicja; Foltyn, Natalia; Dębski, Wojciech

    2017-04-01

    The earthquake focus is the point where a rock under external stress starts to fracture. Understanding earthquake nucleation and earthquake dynamics requires thus understanding of fracturing of brittle materials. This, however, is a continuing problem and enduring challenge to geoscience. In spite of significant progress we still do not fully understand the failure of rock materials due to extreme stress concentration in natural condition. One of the reason of this situation is that information about natural or induced seismic events is still not sufficient for precise description of physical processes in seismic foci. One of the possibility of improving this situation is using numerical simulations - a powerful tool of contemporary physics. For this reason we used an advanced implementation of the Discrete Element Method (DEM). DEM's main task is to calculate physical properties of materials which are represented as an assembly of a great number of particles interacting with each other. We analyze the possibility of using DEM for describing materials during so called Brazilian Test. Brazilian Test is a testing method to obtain the tensile strength of brittle material. One of the primary reasons for conducting such simulations is to measure macroscopic parameters of the rock sample. We would like to report our efforts of describing the fracturing process during the Brazilian Test from the microscopic point of view and give an insight into physical processes preceding materials failure.

  7. Quantification and comparison of the mechanical properties of four human cardiac valves.

    Science.gov (United States)

    Pham, Thuy; Sulejmani, Fatiesa; Shin, Erica; Wang, Di; Sun, Wei

    2017-05-01

    Although having the same ability to permit unidirectional flow within the heart, the four main valves-the mitral valve (MV), aortic (AV), tricuspid (TV) and pulmonary (PV) valves-experience different loading conditions; thus, they exhibit different structural integrity from one another. Most research on heart valve mechanics have been conducted mainly on MV and AV or an individual valve, but none quantify and compare the mechanical and structural properties among the four valves from the same aged patient population whose death was unrelated to cardiovascular disease. A total of 114 valve leaflet samples were excised from 12 human cadavers whose death was unrelated to cardiovascular disease (70.1±3.7years old). Tissue mechanical and structural properties were characterized by planar biaxial mechanical testing and histological methods. The experimental data were then fitted with a Fung-type constitutive model. The four valves differed substantially in thickness, degree of anisotropy, and stiffness. The leaflets of the left heart (the AV leaflets and the anterior mitral leaflets, AML) were significantly stiffer and less compliant than their counterparts in the right heart. TV leaflets were the most extensible and isotropic, while AML and AV leaflets were the least extensible and the most anisotropic. Age plays a significant role in the reduction of leaflet stiffness and extensibility with nearly straightened collagen fibers observed in the leaflet samples from elderly groups (65years and older). Results from 114 human leaflet samples not only provided a baseline quantification of the mechanical properties of aged human cardiac valves, but also offered a better understanding of the age-dependent differences among the four valves. It is hoped that the experimental data collected and the associated constitutive models in this study can facilitate future studies of valve diseases, treatments and the development of interventional devices. Most research on heart valve

  8. 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...

  9. Metallurgical analysis of failed Björk-Shiley cardiac valve prostheses.

    Science.gov (United States)

    Sacks, S H; Harrison, M; Bischler, P J; Martin, J W; Watkins, J; Gunning, A

    1986-01-01

    An investigation into the mechanisms of failure of current Björk-Shiley cardiac valve prostheses is reported. Two failed valves, one apparently unfailed but defective valve, and one unused valve, were examined by scanning electron microscopy and metallographic section. In the first two valves (removed 12 and 23 months after implantation) fracture was associated with the welds joining the short strut to the valve ring. The fracture surfaces in all cases were heavily faceted and showed branching cracks. Extensive wear had occurred on one fracture surface in the first case, suggesting that one leg of the short strut had failed before the other, though this had been clinically undetectable. The third valve was removed owing to failure of the suturing (24 months after implantation) but one leg of the short strut was found to be completely fractured. The other leg showed extensive cracking and porosity in the weld region. A metallographic section taken through the weld region of the fourth (unused) valve illustrated several sizable defects directly attributable to the welding process. It is suggested that the valves failed by fatigue and that these problems could be overcome if the complete valve cage were machined as a single piece. Images PMID:3704981

  10. A newly designed jellyfish valve for an artificial heart blood pump.

    Science.gov (United States)

    Imachi, K; Fujimasa, I; Mabuchi, K; Chinzei, T; Abe, Y; Maeda, K; Imanishi, K; Kouno, A; Ono, T; Atsumi, K

    1988-01-01

    Bjork-Shiley and Hall valves used in most artificial heart blood pumps have often induced problems, which include 1) An expensive valve must be used even when the AH is used for only a few days, 2) Ring thrombus was often formed at the interface between the valve ring and blood pump, seamless fabrication was not possible, and 3) Mechanical failure often occurred. To improve these circumstances, a new jellyfish valve was designed and manufactured. The valve has a simple structure: The center of a thin circular polyurethane membrane is fixed on a polyurethane base plate, which has many holes or slits to reduce flow resistance and help hold the membrane during the diastolic phase. In a mock circulation study, the valve displayed performance similar to the Bjork-Shiley valve. A small amount of regurgitant flow was observed at valve closure, in comparison with the Bjork-Shiley valve. It was recognized in the flow visualization study that the central region of the membrane was washed out well by the flapping of the membrane. This jellyfish valve is promising for use in a AH blood pump.

  11. Left-sided approach for mitral valve replacement in a case of dextrocardia with situs solitus.

    Science.gov (United States)

    Kikon, Mhonchan; Kazmi, Aamir; Gupta, Anubhav; Grover, Vijay

    2013-11-01

    Mitral valve surgery in dextrocardia is technically challenging due to its anatomical malposition. Minor modifications are required in the surgical technique to counteract the problems during cannulation and exposure of the mitral valve. We report a case of a patient with dextrocardia, situs solitus, rheumatic heart disease, severe mitral regurgitation, moderate pulmonary artery hypertension, and severe left ventricular dysfunction who underwent mitral valve replacement using a two-stage right atrial cannulation with left-sided left atrial atriotomy, with the surgeon standing on the left side of the patient. Our approach for mitral valve surgery in this clinical setting is simple.

  12. Experimental study on the Reynolds and viscous shear stress of bileaflet mechanical heart valves in a pneumatic ventricular assist device.

    Science.gov (United States)

    Lee, Hwansung; Tatsumi, Eisuke; Taenaka, Yoshiyuki

    2009-01-01

    Our group is currently developing a pneumatic ventricular assist device (PVAD). In general, the major causes of hemolysis in a pulsatile VAD are cavitation, and Reynolds shear stress (RSS) in the mechanical heart valve (MHV). In a previous study, we investigated MHV cavitation. To select the optimal bileaflet valve for our PVAD, in the current study, we investigated RSS and viscous shear stress (VSS) downstream of three different types of commercial bileaflet valves by means of 2D particle image velocimetry (PIV). To carry out flow visualization inside the blood pump and near the valve, we designed a model pump with the same configuration as that of our PVAD. Three types of bileaflet valves (i.e., the ATS valve, the St. Jude valve, and the Sorin Bicarbon valve) were mounted at the aortic position of the model pump, and flow was visualized according to the PIV method. The maximum flow velocity and RSS of the Sorin Bicarbon valve were lower than those of the other two bileaflet valves. The maximum VSS was only 1% of the maximum RSS. Thus, the effect of VSS on blood cell trauma was neglected. The Sorin Bicarbon valve exhibited relatively low levels of RSS, and was therefore considered to be the best valve for our PVAD among the three valves tested.

  13. High Reliability Cryogenic Piezoelectric Valve Actuator Project

    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...

  14. Experimental results of the tracheoesophageal tissue connector for improved fixation of shunt valves in laryngectomized patients.

    NARCIS (Netherlands)

    Hallers, E.J.O. ten; Marres, H.A.M.; Houwen, E.B. van der; Jansen, J.A.; Rakhorst, G.; Schutte, H.K.; Kooten, T.G. van; Loon, J.P. van; Verkerke, G.J.

    2006-01-01

    BACKGROUND: After total laryngectomy and voice rehabilitation using a tracheoesophageal shunt valve, patients often have valve-related complications such as leakage. To solve these problems, a tracheoesophageal tissue connector (TE-TC) was devised to serve as an interface between the patient's

  15. Patient experiences of recovery after heart valve replacement: suffering weakness, struggling to resume normality

    DEFF Research Database (Denmark)

    Kikkenborg Berg, Selina; Zwisler, Ann-Dorthe; Pedersen, Birthe D.

    2013-01-01

    Heart valve disease is becoming a public health problem due to increasing life expectancy and new treatment methods. Patients are at risk of developing depression, anxiety or post-traumatic stress disorder after heart valve surgery. To better plan proper care, describing and understanding patients...

  16. New Seat Design and Finite Element Analysis for Anti-Leakage of Globe Valve

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sung Ho [Sunlin College, Pohang (Korea, Republic of); Kang, Gyeong Ah; Kwak, Jae Seob; An, Jun Eun; Jin, Dong Hyun [Pukyong National Univ., Daejeon (Korea, Republic of)

    2016-01-15

    The valves used to control or shut off the flow through a pipeline can be divided into many different types, including gate valves, globe valves, and check valves. Globe valves, in particular, have excellent properties, and because they can easily control the flow under high-pressure conditions, they are generally used in LNG ship and steam pipelines. In this paper, a method for changing the shape of a seat was suggested to solve the valve leakage problem from a structural perspective. In addition, the stress distribution and directional deformation were compared for each model. The suggested models were thus validated, and the optimized seat structure, which includes a self-supporting capability for decreasing the amount of leakage, was determined.

  17. A low-volume tester for the thrombogenic potential of mechanical heart valve prostheses.

    Science.gov (United States)

    Linde, Torsten; Hamilton, Kathrin F; Timms, Daniel L; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2011-09-01

    During the development of a mechanical heart valve prosthesis, many studies are conducted to guarantee its correct function. Currently, investigations into the thrombogenic potential of a valve after its replacement are conducted with expensive and time-consuming chronic animal trials. Hence, the study aim was to develop and test an alternative system to resolve such thrombogenic issues. The Thrombosis Tester of the Helmholtz Institute Aachen (THIA II) has a reasonably small priming volume (220-270 ml) that allows analysis of the thrombogenic potential of two valves, using one human blood bottle. Hydrodynamic evaluation demonstrated an absolutely stable physiological pressure and flow progression at the aortic and pulmonary positions. A sinus geometry of the human aortic root is implemented downstream of the valve in order to guarantee physiological leaflet motion. The tester remained absolutely thrombus-free during several tests carried out with minimally anticoagulated porcine blood, while the valves showed reproducible thrombus formation in reasonable locations. Tests with fully heparinized porcine blood showed that a soft silicon fixture for the valve could reduce hemolysis in the THIA II. This in-vitro test protocol can enable the optimization of a valve design during the early stages of its research and development. The system can provide a unique and suitable supplement to animal trials for testing thrombogenic performance, under constant and reproducible boundary conditions, including considerable physiological and pathological circumstances such as the influence of valve position (aortic, pulmonic), and a comparison of different valve types.

  18. Apixaban Versus Warfarin for Mechanical Heart Valve Thromboprophylaxis in a Swine Aortic Heterotopic Valve Model.

    Science.gov (United States)

    Lester, Patrick A; Coleman, Dawn M; Diaz, Jose A; Jackson, Tatum O; Hawley, Angela E; Mathues, Angela R; Grant, Brandon T; Knabb, Robert M; Ramacciotti, Eduardo; Frost, Charles E; Song, Yan; Wakefield, Thomas W; Myers, Daniel D

    2017-05-01

    Warfarin is the current standard for oral anticoagulation therapy in patients with mechanical heart valves, yet optimal therapy to maximize anticoagulation and minimize bleeding complications requires routine coagulation monitoring, possible dietary restrictions, and drug interaction monitoring. As alternatives to warfarin, oral direct acting factor Xa inhibitors are currently approved for the prophylaxis and treatment of venous thromboembolism and reduction of stroke and systemic embolization. However, no in vivo preclinical or clinical studies have been performed directly comparing oral factor Xa inhibitors such as apixaban to warfarin, the current standard of therapy. A well-documented heterotopic aortic valve porcine model was used to test the hypothesis that apixaban has comparable efficacy to warfarin for thromboprophylaxis of mechanical heart valves. Sixteen swine were implanted with a bileaflet mechanical aortic valve that bypassed the ligated descending thoracic aorta. Animals were randomized to 4 groups: control (no anticoagulation; n=4), apixaban oral 1 mg/kg twice a day (n=5), warfarin oral 0.04 to 0.08 mg/kg daily (international normalized ratio 2-3; n=3), and apixaban infusion (n=4). Postmortem valve thrombus was measured 30 days post-surgery for control-oral groups and 14 days post-surgery for the apixaban infusion group. Control thrombus weight (mean) was significantly different (1422.9 mg) compared with apixaban oral (357.5 mg), warfarin (247.1 mg), and apixiban 14-day infusion (61.1 mg; Pheart valves. Unlike warfarin, no adverse bleeding events were observed in any apixaban groups. © 2017 American Heart Association, Inc.

  19. 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...

  20. Butterfly valve apparatus and method

    Energy Technology Data Exchange (ETDEWEB)

    Ball, L.K.; Hines, M.U.; Miller, T.L.

    1990-10-23

    This patent describes a method of controlling fluid flow in a duct, and duct having a wall bounding a flow path wherein flows the fluid. It comprises: disposing a plate-like valve member in the flow path, which valve member is pivotally movable about an axis generally transverse to the duct between a first position transverse to and closing the flow path and a second position generally parallel with the flow path to open and allow fluid flow therein: transecting the valve member with the pivot axis to define with respect to direction of the fluid flow in the duct and pivotal movement of the valve member toward the open position an upstream valve member wing and a downstream valve member wing each substantially equal in area: increasing the effective area of the valve member upon which the fluid flow exerts fluid dynamic flow forces; and pivoting the valve member toward the second open position thereof in response to the increase of effective area.

  1. The spin-valve transistor

    NARCIS (Netherlands)

    Anil Kumar, P.S.; Lodder, J.C.

    2000-01-01

    The spin-valve transistor is a magnetoelectronic device that can be used as a magnetic field sensor. It has a ferromagnet-semiconductor hybrid structure. Using a vacuum metal bonding technique, the spin-valve transistor structure Si/Pt/NiFe/Au/Co/Au/Si is obtained. It employs hot electron transport

  2. Mechanical Valve Replacement: Early Results

    Directory of Open Access Journals (Sweden)

    Habib Cakir

    2012-03-01

    Conclusion: Mechanical prosthetic valves are used for surgical treatment of valve disease with low mortality and morbidity in a large group of patients like women that not to think to get pregnant, non advanced age group and patients have less risky for anticoagulation drug in our clinic. [Cukurova Med J 2012; 37(1: 49-54

  3. New design method for valves internals, to optimize process

    Energy Technology Data Exchange (ETDEWEB)

    Jorge, Leonardo [PDVSA (Venezuela)

    2011-07-01

    In the heavy oil industry, various methods can be used to reduce the viscosity of oil, one of them being the injection of diluent. This method is commonly used in the Orinoco oil belt but it requires good control of the volume of diluent injected as well as the gas flow to optimize production; thus flow control valves need to be accurate. A new valve with a new method was designed with the characteristic of being very reliable and was then bench tested and compared with the other commercially available valves. Results showed better repeatability, accuracy and reliability with lower maintenance for the new method. The use of this valve provides significant savings while distributing the exact amount of fluids; up to date a less than 2% failure rate has been recorded in the field. The new method developed demonstrated impressive performance and PDVSA has decided to use it in mass.

  4. A design strategy for magnetorheological dampers using porous valves

    Energy Technology Data Exchange (ETDEWEB)

    Hu, W; Robinson, R; Wereley, N M [Smart Structures Laboratory, Alfred Gessow Rotorcraft Center, Department of Aerospace Engineering, University of Maryland, College Park, MD 20742 (United States)], E-mail: wereley@umd.edu

    2009-02-01

    To design a porous-valve-based magnetorheological (MR) damper, essential design parameters are presented. The key elements affecting the damper performance are identified using flow analysis in porous media and an empirical magnetic field distribution in the porous valve. Based on a known MR fluid, the relationship between the controllable force of the damper and the porous valve characteristics, i.e. porosity and tortuosity, is developed. The effect of the porosity and tortuosity on the field-off damping force is exploited by using semi-empirical flow analysis. The critical flow rate for the onset of nonlinear viscous damping force is determined. Using the above design elements, an MR damper using by-pass porous valve is designed and tested. The experimental damper force and equivalent damping are compared with the predicted results to validate this design strategy.

  5. Results of Additional Bioventing Respiration Testing at Sites ST61, ST71, and ST43/55 (Pumphouse III and Valve Pit 3-4)

    National Research Council Canada - National Science Library

    1996-01-01

    ...). Vent well and monitoring point construction, respiration and air permeability testing, soil and soil gas sampling, and blower system installation and startup was performed at each site as part of the initial testing...

  6. INVASIVE WEED OPTIMIZATION FOR ECONOMIC DISPATCH WITH VALVE POINT EFFECTS

    Directory of Open Access Journals (Sweden)

    RAMA PRABHA D.

    2016-02-01

    Full Text Available This paper proposes a novel optimization methodology aimed at solving economic dispatch (ED problem considering valve point effects using invasive weed optimization (IWO algorithm. IWO was recently proposed as a simple but powerful metaheuristic algorithm for real parameter optimization. IWO draws inspiration from the ecological process of weeds colonization and distribution and is capable of solving general multi-dimensional, linear and nonlinear optimization problems with appreciable efficiency. The proposed method has been applied to three test systems comprising 3, 13 and 40 units. These test systems are also solved using the catfish particle swarm optimisation (Catfish PSO algorithm - an improved version of PSO - for the comparison and validation of the solutions. The obtained best values have been compared with different methods in literature and the results of them have been discussed. The result obtained proves that the IWO algorithm is efficient and can be used practically for solving economic dispatch problem. A comparative analysis with other settled nature-inspired solution algorithms demonstrates the superior performance of the proposed methodology in terms of both solution accuracy and convergence performances.

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

    Energy Technology Data Exchange (ETDEWEB)

    Schlereth, J.R.; Pennington, D.

    1996-12-01

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

  8. Dynamic Economic Dispatch Using Hybrid DE-SQP for Generating Units with Valve-Point Effects

    Directory of Open Access Journals (Sweden)

    A. M. Elaiw

    2012-01-01

    Full Text Available This paper presents hybrid differential evolution (DE and sequential quadratic programming (SQP for solving the dynamic economic dispatch (DED problem for generating units with valve-point effects. DE is used as a global optimizer and SQP is used as a fine tuning to determine the optimal solution at the final. The feasibility of the proposed method is validated with five-and ten-unit test systems. Results obtained by DE-SQP method are compared with other techniques in the literature.

  9. Percutaneous transcatheter one-step mechanical aortic disc valve prosthesis implantation: a preliminary feasibility study in swine.

    Science.gov (United States)

    Sochman, Jan; Peregrin, Jan H; Rocek, Miloslav; Timmermans, Hans A; Pavcnik, Dusan; Rösch, Josef

    2006-01-01

    To evaluate the feasibility of one-step implantation of a new type of stent-based mechanical aortic disc valve prosthesis (MADVP) above and across the native aortic valve and its short-term function in swine with both functional and dysfunctional native valves. The MADVP consisted of a folding disc valve made of silicone elastomer attached to either a nitinol Z-stent (Z model) or a nitinol cross-braided stent (SX model). Implantation of 10 MADVPs (6 Z and 4 SX models) was attempted in 10 swine: 4 (2 Z and 2 SX models) with a functional native valve and 6 (4 Z and 2 SX models) with aortic regurgitation induced either by intentional valve injury or by MADVP placement across the native valve. MADVP function was observed for up to 3 hr after implantation. MADVP implantation was successful in 9 swine. One animal died of induced massive regurgitation prior to implantation. Four MADVPs implanted above functioning native valves exhibited good function. In 5 swine with regurgitation, MADVP implantation corrected the induced native valve dysfunction and the device's continuous good function was observed in 4 animals. One MADVP (SX model) placed across native valve gradually migrated into the left ventricle. The tested MADVP can be implanted above and across the native valve in a one-step procedure and can replace the function of the regurgitating native valve. Further technical development and testing are warranted, preferably with a manufactured MADVP.

  10. Pilot study risk assessment for selected problems at the Nevada Test Site (NTS)

    Energy Technology Data Exchange (ETDEWEB)

    Daniels, J.I. [ed.; Anspaugh, L.R.; Bogen, K.T.; Daniels, J.I.; Layton, D.W.; Straume, T. [Lawrence Livermore National Lab., CA (United States); Andricevic, R.; Jacobson, R.L. [Nevada Univ., Las Vegas, NV (United States). Water Resources Center; Meinhold, A.F.; Holtzman, S.; Morris, S.C.; Hamilton, L.D. [Brookhaven National Lab., Upton, NY (United States)

    1993-06-01

    The Nevada Test Site (NTS) is located in southwestern Nevada, about 105 km (65 mi) northwest of the city of Las Vegas. A series of tests was conducted in the late 1950s and early 1960s at or near the NTS to study issues involving plutonium-bearing devices. These tests resulted in the dispersal of about 5 TBq of {sup 239,24O}Pu on the surficial soils at the test locations. Additionally, underground tests of nuclear weapons devices have been conducted at the NTS since late 1962; ground water beneath the NTS has been contaminated with radionuclides produced by these tests. These two important problems have been selected for assessment. Regarding the plutonium contamination, because the residual {sup 239}Pu decays slowly (half-life of 24,110 y), these sites could represent a long-term hazard if they are not remediated and if institutional controls are lost. To investigate the magnitude of the potential health risks for this no-remediation case, three basic exposure scenarios were defined that could bring individuals in contact with {sup 239,24O}Pu at the sites: (1) a resident living in a subdivision, (2) a resident farmer, and (3) a worker at a commercial facility -- all located at a test site. The predicted cancer risks for the resident farmer were more than a factor of three times higher than the suburban resident at the median risk level, and about a factor of ten greater than the reference worker at a commercial facility. At 100 y from the present, the 5, 50, and 95th percentile risks for the resident farmer at the most contaminated site were 4 x 10{sup {minus}6}, 6 x 10{sup {minus}5}, and 5 x 10{sup {minus}4}, respectively. For the assessment of Pu in surface soil, the principal sources of uncertainty in the estimated risks were population mobility, the relationship between indoor and outdoor contaminant levels, and the dose and risk factors for bone, liver, and lung.

  11. Pilot study risk assessment for selected problems at the Nevada Test Site (NTS)

    Energy Technology Data Exchange (ETDEWEB)

    Daniels, J.I. (ed.)

    1993-06-01

    The Nevada Test Site (NTS) is located in southwestern Nevada, about 105 km (65 mi) northwest of the city of Las Vegas. A series of tests was conducted in the late 1950s and early 1960s at or near the NTS to study issues involving plutonium-bearing devices. These tests resulted in the dispersal of about 5 TBq of [sup 239,24O]Pu on the surficial soils at the test locations. Additionally, underground tests of nuclear weapons devices have been conducted at the NTS since late 1962; ground water beneath the NTS has been contaminated with radionuclides produced by these tests. These two important problems have been selected for assessment. Regarding the plutonium contamination, because the residual [sup 239]Pu decays slowly (half-life of 24,110 y), these sites could represent a long-term hazard if they are not remediated and if institutional controls are lost. To investigate the magnitude of the potential health risks for this no-remediation case, three basic exposure scenarios were defined that could bring individuals in contact with [sup 239,24O]Pu at the sites: (1) a resident living in a subdivision, (2) a resident farmer, and (3) a worker at a commercial facility -- all located at a test site. The predicted cancer risks for the resident farmer were more than a factor of three times higher than the suburban resident at the median risk level, and about a factor of ten greater than the reference worker at a commercial facility. At 100 y from the present, the 5, 50, and 95th percentile risks for the resident farmer at the most contaminated site were 4 x 10[sup [minus]6], 6 x 10[sup [minus]5], and 5 x 10[sup [minus]4], respectively. For the assessment of Pu in surface soil, the principal sources of uncertainty in the estimated risks were population mobility, the relationship between indoor and outdoor contaminant levels, and the dose and risk factors for bone, liver, and lung.

  12. Moderate exercise does not increase the severity of mitral regurgitation due to mitral valve prolapse

    DEFF Research Database (Denmark)

    Pecini, Redi; Dalsgaard, Morten; Møller, Daniel Vega

    2010-01-01

    Mitral regurgitation (MR) secondary to ischemic heart disease (IHD) increases during exercise. We tested the hypothesis that the same is also true for MR due to mitral valve prolapse (MVP).......Mitral regurgitation (MR) secondary to ischemic heart disease (IHD) increases during exercise. We tested the hypothesis that the same is also true for MR due to mitral valve prolapse (MVP)....

  13. Development of a control system for compression and expansion cycles of critical valve for high vacuum systems

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Jyoti, E-mail: jagarwal@ipr.res.in; Sharma, H.; Patel, Haresh; Gangradey, R.; Lambade, Vrushabh

    2016-11-15

    Highlights: • Control system with feedback loop of pressure gauge is developed for measuring the life cycle of vacuum isolation valve. • GUI based software developed for easy use and handling of control system. • Control system tested with an experiment showcasing the capability of the control system. • Control system can operate valve based on pressure inside the chamber, which helps to know the degradation of sealing capabilities of valve. • Control system can monitor the total closing and opening time of valve, cycles and pressure inside the vessel. - Abstract: A control system with feedback loop is designed, developed and tested to monitor the life cycles of the axial valve and bellows used in vacuum valves. The control system monitors number of compression cycles of any bellow or closing and opening cycle of a valve. It also interfaces vacuum gauges or pressure gauges to get pressure values inside the system. To find life cycle of valve, the developed control and monitoring system is integrated with an axial valve experimental test set up. In this system, feedback from the vacuum gauge attached to valve enclosure, is given and the life cycle test is automated. This paper describes the control and monitoring system in details and briefs the experiment carried out for valve life cycle. The same system can be used for life cycle estimate for bellows. A suitable GUI is also developed to control the function of the components and resister the number of cycles.

  14. Analysis of regurgitation, mean systolic pressure drop and energy losses for two artificial aortic valves.

    Science.gov (United States)

    Sakhaeimanesh, A A; Morsi, Y S

    1999-01-01

    The work reported here is related to the hydrodynamic performance of a Jellyfish valve and St Vincent valve in terms of total energy losses, mean systolic pressure drop and regurgitation. The in vitro experimental investigation was conducted at cardiac outputs of 3.5, 4.5 and 6.51 min-1 across the two valves and under pulsatile flow condition. It was found that the closure volume of the St Vincent valve was about 2.5 times higher than that of the Jellyfish valve. The total back flow losses on the other hand were found to be in the range of 36.5 to 107.1 and 85.5 to 192.5 mJ for the Jellyfish valve and St Vincent valve respectively. Moreover, the mean systolic pressure drop of the St Vincent valve was found to be higher than that of the Jellyfish valve. However, for all the operating conditions tested here, the Jellyfish valve showed superior hydrodynamic performance in terms of backflow and mean systolic pressure as well as energy losses.

  15. Cracking a tricuspid perimount bioprosthesis to optimize a second transcatheter sapien valve-in-valve placement.

    Science.gov (United States)

    Brown, Stephen C; Cools, Bjorn; Gewillig, Marc

    2016-09-01

    Bioprosthetic valves degenerate over time. Transcatheter valve-in-valve procedures have become an attractive alternative to surgery. However, every valve increasingly diminishes the diameter of the valvar orifice. We report a 12-year-old female who had a previous transcatheter tricuspid valve-in-valve procedure; cracking the ring of a Carpentier Edwards Perimount valve by means of an ultrahigh pressure balloon allowed implantation of a further larger percutaneous valve. The advantage of this novel approach permits enlarging the inner valve diameter and may facilitate future interventions and prolong time to surgery. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  16. 3D velocity field characterization of prosthetic heart valve with two different valve testers by means of stereo-PIV.

    Science.gov (United States)

    D'Avenio, Giuseppe; Grigioni, Mauro; Daniele, Carla; Morbiducci, Umberto; Hamilton, Kathrin

    2015-01-01

    Prosthetic heart valves can be associated to mechanical loading of blood, potentially linked to complications (hemolysis and thrombogenicity) which can be clinically relevant. In order to test such devices in pulsatile mode, pulse duplicators (PDs) have been designed and built according to different concepts. This study was carried out to compare anemometric measurements made on the same prosthetic device, with two widely used PDs. The valve (a 27-mm bileaflet valve) was mounted in the aortic section of the PD. The Sheffield University PD and the RWTH Aachen PD were selected as physical models of the circulation. These two PDs differ mainly in the vertical vs horizontal realization, and in the ventricular section, which in the RWTH PD allows for storage of potential energy in the elastic walls of the ventricle. A glassblown aorta, realized according to the geometric data of the same anatomical district in healthy individuals, was positioned downstream of the valve, obtaining 1:1 geometric similarity conditions. A NaI-glycerol-water solution of suitable kinematic viscosity and, at the same time, the proper refractive index, was selected. The flow field downstream of the valve was measured by means of the stereo-PIV (Particle Image Velocimetry) technique, capable of providing the complete 3D velocity field as well as the entire Reynolds stress tensor. The measurements were carried out at the plane intersecting the valve axis. A three-jet profile was clearly found in the plane crossing the leaflets, with both PDs. The extent of the typical recirculation zone in the Valsalva sinus was much larger in the RWTH PD, on account of the different duration of the swirling motion in the ventricular chamber, caused by the elasticity of the ventricle and its geometry. The comparison of the hemodynamical behaviour of the same bileaflet valve tested in two PDs demonstrated the role of the mock loop in affecting the valve performance.

  17. Preparatory balloon aortic valvuloplasty during transcatheter aortic valve implantation for improved valve sizing.

    Science.gov (United States)

    Patsalis, Polykarpos C; Al-Rashid, Fadi; Neumann, Till; Plicht, Björn; Hildebrandt, Heike A; Wendt, Daniel; Thielmann, Matthias; Jakob, Heinz G; Heusch, Gerd; Erbel, Raimund; Kahlert, Philipp

    2013-09-01

    This study sought to evaluate whether supra-aortic angiography during preparatory balloon aortic valvuloplasty (BAV) improves valve sizing. Current recommendations for valve size selection are based on annular measurements by transesophageal echocardiography and computed tomography, but paravalvular aortic regurgitation (PAR) is a frequent problem. Data of 270 consecutive patients with either conventional sizing (group 1, n = 167) or balloon aortic valvuloplasty-based sizing (group 2, n = 103) were compared. PAR was graded angiographically and quantitatively using several hemodynamic indices. PAR was observed in 113 patients of group 1 and 41 patients of group 2 (67.7% vs. 39.8%, p < 0.001). More than mild PAR was found in 24 (14.4%) patients of group 1 and 8 (7.8%) patients of group 2. According to pre-interventional imaging, 40 (39%) patients had a borderline annulus size, raising uncertainty regarding valve size selection. Balloon sizing resulted in selection of the bigger prosthesis in 30 (29%) and the smaller prosthesis in the remaining patients, and only 1 of these 40 patients had more than mild PAR. As predicted by the hemodynamic indices of PAR, mortality at 30 days and 1 year was less in group 2 than in group 1 (5.8% vs. 9%, p = 0.2 and 10.6% vs. 20%, p = 0.01). Preparatory balloon aortic valvuloplasty during transcatheter aortic valve implantation improves valve size selection, reduces the associated PAR, and increases survival in borderline cases. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  18. 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 ...

  19. [Heart valve prosthesis and pregnancy].

    Science.gov (United States)

    Ben-Ismail, M; Fekih, M; Taktak, M; Chelli, M

    1979-02-01

    Sixteen pregnancies were followed up in 13 patients with prosthetic heart valves: 8 pregnancies went to term under oral anticoagulation, 4 under heparin and 4 without anticoagulation. 9 healthy normal children were delivered; there were 2 still births and 5 abortions. On the maternal side 3 haemorrhages and thromboembolic episodes which involved 2 patients on heparin, one of whom died, were observed. The following points are apparent from our observations and a review of the existing medical literature: --the risk of thromboembolism is not increased. The marked clotting tendency of maternal blood post-partum contraindicates the withdrawal of anticoagulants during this critical period; --haemorrhagic complications are common with anticoagulants; --foetal loss is greatly increased; --the teratogenecity of vitamin-K antagonists is certain, but the risk is small. The problems of anticoagulation are discussed; theoretically heparin should be given during the 1st trimestre and from the 38th week to the second post-partum week. The patients should be closely supervised by both obstetrician and cardiologist and hospitalisation is advised for the last month of pregnancy. Normal vaginal delivery is usually possible.

  20. Energy Regeneration Hydraulic System via a Relief Valve with Energy Regeneration Unit

    Directory of Open Access Journals (Sweden)

    Tianliang Lin

    2017-06-01

    Full Text Available Relief valves are widely used in industrial machinery. Due to the outlet of the relief valve being connected to the tank, the pressure drop of the relief valve is frequently equal to the inlet pressure. Accordingly, the energy loss of the relief valve is very high in some cases and this will worsen with an increase in the rated pressure of the hydraulic system. In order to overcome the disadvantage of overflow energy loss in a relief valve, a hydraulic energy regeneration unit (HERU is connected to the outlet of the relief valve to decrease the pressure drop between the inlet and outlet of the relief valve. The overflow loss, which is characterized by the pressure drop, can be reduced accordingly. The approach is to convert the overflow energy loss in hydraulic form and allow for release when needed. The configuration and working principle of the relief valve with HERU is introduced in this present study. The mathematical model is established to obtain the factors influencing the stability of the relief valve. The working pressure of the hydraulic accumulator (HA is explored. Furthermore, the control process of the operating state of the HA is scheduled to decide whether to regenerate the energy via the HERU. The software AMESim is utilized to analyze the performance and characteristics of the relief valve with HERU. Following this, the test rig is built and used to verify the effectiveness of the proposed relief valve with HERU. The experimental results show that the relief valve with the HERU connected to its outlet can still achieve better pressure-regulating characteristics. The energy regeneration efficiency saved by the HA is up to 83.6%, with a higher pre-charge pressure of the HA. This indicates that the proposed structure of the relief valve with HERU can achieve a better performance and higher regeneration efficiency.

  1. Human antibody recognition of xenogeneic antigens (NeuGc and Gal) on porcine heart valves: could genetically modified pig heart valves reduce structural valve deterioration?

    Science.gov (United States)

    Lee, Whayoung; Long, Cassandra; Ramsoondar, Jagdeece; Ayares, David; Cooper, David K C; Manji, Rizwan A; Hara, Hidetaka

    2016-09-01

    Glutaraldehyde-fixed bioprosthetic heart valves (GBHVs) derived from wild-type (WT, genetically unmodified) pigs are widely used clinically for heart valve replacement. There is evidence that their failure is related to an immune response. The use of valves from genetically engineered pigs that do not express specific pig antigens may prolong GBHV survival. Our aims were to determine (i) expression of Gal and NeuGc on heart (aortic and pulmonary) valves and pericardium of WT, α1,3-galactosyltransferase gene knockout (GTKO) and GTKO/N-glycolylneuraminic acid gene-knockout (GTKO/NeuGcKO) pigs in comparison with three different commercially available GBHVs and (ii) to determine human antibody binding to these tissues. Wild-type, GTKO/CD46, and GTKO/CD46/NeuGcKO pig valves and pericardium were tested (i) fresh and (ii) after fixation with glutaraldehyde (0.02%, 0.2%, 2%). Sections of GBHVs, fresh and fixed valves, and pericardium were stained for Gal and NeuGc expression, and for human IgM and IgG antibody binding. Gal and NeuGc expression was high on all GBHVs and WT pig valves/pericardium, but was absent after antigen-specific-knockout. There was no difference in antigen expression or antibody binding among WT aortic, pulmonary valves, and pericardium as well as GBHVs. Glutaraldehyde fixation did not alter expression of Gal or NeuGc. After incubation with human serum, human IgM and IgG bound to all GBHVs and WT pig valves/pericardium. Valves from GTKO/CD46 pigs and, particularly, GTKO/CD46/NeuGcKO pigs (with/without glutaraldehyde fixation) showed less IgM and IgG binding. Compared to WT pigs, GTKO/CD46/NeuGcKO pigs would be preferable sources of GBHVs, because the absence of Gal/NeuGc expression reduces human antibody binding. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Decellularized mitral valve in a long-term sheep model.

    Science.gov (United States)

    Iablonskii, Pavel; Cebotari, Serghei; Ciubotaru, Anatol; Sarikouch, Samir; Hoeffler, Klaus; Hilfiker, Andres; Haverich, Axel; Tudorache, Igor

    2018-01-29

    The objective of this study was to evaluate surgical handling, in vivo hemodynamic performance and morphological characteristics of decellularized mitral valves (DMVs) in a long-term sheep model. Ovine mitral valves were decellularized using detergents and β-mercaptoethanol. Orthotopic implantations were performed in 6-month-old sheep (41.3 ± 1.2 kg, n = 11) without annulus reinforcement. Commercially available stented porcine aortic valves [biological mitral valve (BMV), n = 3] were implanted conventionally and used as controls. Valve function was evaluated by transoesophageal echocardiography and explants were investigated by a routine bright field microscopy and immunofluorescent histology. During implantation, 2 DMVs required cleft closure of the anterior leaflet. All valves were competent on water test and early postoperative transoesophageal echocardiography. Six animals (DMV, n = 4; BMV, n = 2) survived 12 months. Six animals died within the first 4 months due to valve-related complications. At 12 months, transoesophageal echocardiography revealed severe degeneration in all BMVs. Macroscopically, BMV revealed calcification at the commissures and leaflet insertion area. Histological examination showed sporadic cells negative for endothelial nitric oxide synthase, von Willebrand factor and CD45 on their surface. In contrast, DMV showed no calcification or stenosis, and the regurgitation was trivial to moderate in all animals. Fibrotic hardening occurred only along the suture line of the valve annulus, immunostaining revealed collagen IV covering the entire leaflet surface and a repopulation with endothelial cells. Surgical implantation of DMV is feasible and results in good early graft function. Additional in vivo investigations are required to minimize the procedure-related complications and to increase the reproducibility of surgical implantation. Degenerative profile of allogeneic DMV is superior to commercially available

  3. Internal Acoustics of a Pintle Valve with Supercritical Helium Flow

    Science.gov (United States)

    Fishbach, Sean R.; Davis, R. Benjamin

    2010-01-01

    Large amplitude flow unsteadiness is a common phenomenon within the high flow rate ducts and valves associated with propulsion systems. Boundary layer noise, shear layers and vortex shedding are a few of the many sources of flow oscillations. The presence of lightly damped acoustic modes can organize and amplify these sources of flow perturbation, causing undesirable loading of internal parts. The present study investigates the self-induced acoustic environment within a pintle valve subject to high Reynolds Number flow of helium gas. Experiments were conducted to measure the internal pressure oscillations of the Ares I Launch Abort System (LAS) Attitude Control Motor (ACM) valve. The AGM consists of a solid propellant gas generator with eight pintle valves attached to the aft end. The pintle valve is designed to deliver variable upstream conditions to an attache( converging diverging nozzle. In order to investigate the full range of operating conditions 28 separate tests were conducted with varying pintle position and upstream pressure. Helium gas was utilized in order to closely mimic the speed of sound of the gas generator exhaust, minimizing required scaling during data analysis. The recordec pressure measurements were interrogated to multiple ends. The development of root mean square (RMS) value! versus Reynolds Number and Pintle position are important to creating bounding unsteady load curves for valve internal parts. Spectral analysis was also performed, helping to identify power spectral densities (PSD) of acoustic natural frequencies and boundary layer noise. An interesting and unexpected result was the identification of an acoustic mode within the valve which does not respond until the valve was over 60% open. Further, the response amplitude around this mode can be as large or larger than those associated with lower frequency modes.

  4. Pressure locking and thermal binding of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, E.M.

    1996-12-01

    Pressure locking and thermal binding represent potential common mode failure mechanisms that can cause safety-related power-operated gate valves to fail in the closed position, thus rendering redundant safety-related systems incapable of performing their safety functions. Supplement 6 to Generic Letter 89-10, {open_quotes}Safety-Related Motor-Operated Gate Valve Testing and Surveillance,{close_quotes} provided an acceptable approach to addressing pressure locking and thermal binding of gate valves. More recently, the NRC has issued Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves,{close_quotes} to request that licensees take certain actions to ensure that safety-related power-operated gate valves that are susceptible to pressure locking or thermal binding are capable of performing their safety functions within the current licensing bases. Over the past two years, several plants in Region I determined that valves in certain systems were potentially susceptible to pressure locking and thermal binding, and have taken various corrective actions. The NRC Region I Systems Engineering Branch has been actively involved in the inspection of licensee actions in response to the pressure locking and thermal binding issue. Region I continues to maintain an active involvement in this area, including participation with the Office of Nuclear Reactor Regulation in reviewing licensee responses to Generic Letter 95-07.

  5. Testing a Comprehensive Community Problem-Solving Framework for Community Coalitions

    Science.gov (United States)

    Yang, Evelyn; Foster-Fishman, Pennie; Collins, Charles; Ahn, Soyeon

    2012-01-01

    Community problem solving is believed to help coalitions achieve community changes and subsequent population-level reductions in targeted community health problems. This study empirically examined a community problem solving model used by CADCA, a national coalition training organization, to determine if the model explains how coalitions become…

  6. Stem thrust prediction model for Westinghouse wedge gate valves with linkage type stem-to-disk connection

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.K.; Sharma, V.; Kalsi, M.S. [Kalsi Engineering, Inc., Sugar Land, TX (United States)] [and others

    1996-12-01

    The Electric Power Research Institute (EPRI) conducted a comprehensive research program with the objective of providing nuclear utilities with analytical methods to predict motor operated valve (MOV) performance under design basis conditions. This paper describes the stem thrust calculation model developed for evaluating the performance of one such valve, the Westinghouse flexible wedge gate valve. These procedures account for the unique functional characteristics of this valve design. In addition, model results are compared to available flow loop and in situ test data as a basis for evaluating the performance of the valve model.

  7. 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.

  8. Performance characterization of a solenoid-type gas valve for the H- magnetron source at FNAL

    Science.gov (United States)

    Sosa, A.; Bollinger, D. S.; Karns, P. R.

    2017-08-01

    The magnetron-style H- ion sources currently in operation at Fermilab use piezoelectric gas valves to function. This kind of gas valve is sensitive to small changes in ambient temperature, which affect the stability and performance of the ion source. This motivates the need to find an alternative way of feeding H2 gas into the source. A solenoid-type gas valve has been characterized in a dedicated off-line test stand to assess the feasibility of its use in the operational ion sources. H- ion beams have been extracted at 35 keV using this valve. In this study, the performance of the solenoid gas valve has been characterized measuring the beam current output of the magnetron source with respect to the voltage and pulse width of the signal applied to the gas valve.

  9. The study on flow characteristics of butterfly valve using flow visualization

    Energy Technology Data Exchange (ETDEWEB)

    Yang, S. M.; Hong, S. D.; Song, D. S.; Park, J. K.; Park, J. I.; Shin, S. K. [Hanbit Power Service, Daejeon (Korea, Republic of); Kim, H. J. [Ajou University, Suwon (Korea, Republic of)

    2005-07-01

    Flow visualization of butterfly valve is tested for four types(15 deg., 30 .deg., 45 .deg., and 90 .deg.) of valve opening angle. The inner flow characteristics of valve are studied. The flow variation was measured using a high speed camera which takes 500 frames per second with 1024 x 1024 pixels. These captured images were used for calculation to analyze two dimensional flow velocity of the valve. The smaller opening angle, the more increasing the differential pressure of a butterfly valve. Therefore, we know that the complex flow is occurred by increasing the differential pressure. And it is found that the flowing backward is more increased according to the increase of the opening angle of a butterfly valve. However, its flow pattern is similar to a simple pipe flow when the opening angle is 90 .deg.

  10. Performance Characterization of a Solenoid-type Gas Valve for the H- Magnetron Source at FNAL

    Energy Technology Data Exchange (ETDEWEB)

    Sosa, A. [Fermilab; Bollinger, D. S. [Fermilab; Karns, P. R. [Fermilab

    2016-09-06

    The magnetron-style H- ion sources currently in operation at Fermilab use piezoelectric gas valves to function. This kind of gas valve is sensitive to small changes in ambient temperature, which affect the stability and performance of the ion source. This motivates the need to find an alternative way of feeding H2 gas into the source. A solenoid-type gas valve has been characterized in a dedicated off-line test stand to assess the feasibility of its use in the operational ion sources. H- ion beams have been extracted at 35 keV using this valve. In this study, the performance of the solenoid gas valve has been characterized measuring the beam current output of the magnetron source with respect to the voltage and pulse width of the signal applied to the gas valve.

  11. Effectiveness of dabigatran etexilate for thromboprophylaxis of mechanical heart valves.

    Science.gov (United States)

    McKellar, Stephen H; Abel, Stuart; Camp, Christopher L; Suri, Rakesh M; Ereth, Mark H; Schaff, Hartzell V

    2011-06-01

    Warfarin reduces risk of stroke in patients with mechanical heart valves but increases risk of hemorrhage and is difficult to use. Dabigatran etexilate, a new oral direct thrombin inhibitor, is safe and effective in reducing risk of stroke among patients with atrial fibrillation. No data exist in the setting of mechanical heart valves. We tested the hypothesis that dabigatran etexilate is as effective as heparin for thromboprophylaxis of mechanical valves in a porcine heterotopic aortic valve model. Thirty swine underwent implantation of modified bileaflet mechanical valved conduit bypassing the ligated, native descending thoracic aorta. Animals randomly received no anticoagulation (n = 10), enoxaparin 2 mg/kg subcutaneously twice daily (n = 10), or dabigatran etexilate 20 mg/kg orally twice daily. Primary end point was amount of valve thrombus at 30 days. Secondary end points included quantitative measurement of platelet deposition on valve prosthesis, thromboelastography, and hemorrhagic and embolic events. At 30 days, we observed 638 ± 895 mg thrombus in no anticoagulation group, 121 ± 128 mg in enoxaparin group, and 19 ± 31 mg in dabigatran etexilate group (P = .01 enoxaparin vs dabigatran etexilate). Fewer platelets were deposited on valves in dabigatran etexilate group (2.7 × 10(8)) than in enoxaparin group (1.8 × 10(9), P = .03). No major or occult hemorrhagic or embolic events were observed. By thromboelastographic analysis, dabigatran etexilate produced less prolongation of K value (P = .01) and less decreases in angle (P = .01) and maximum amplitude (P = .001) than enoxaparin. Dabigatran etexilate is as effective as enoxaparin for short-term thromboprophylaxis of mechanical valves. It prevents valve thrombus and platelet deposition at 30 days without increased adverse events. These promising results serve as a foundation for prospective clinical trials with dabigatran etexilate as an alternative to warfarin in patients with bileaflet

  12. 49 CFR 40.201 - What problems always cause a drug test to be cancelled and may result in a requirement for...

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false What problems always cause a drug test to be... Office of the Secretary of Transportation PROCEDURES FOR TRANSPORTATION WORKPLACE DRUG AND ALCOHOL TESTING PROGRAMS Problems in Drug Tests § 40.201 What problems always cause a drug test to be cancelled...

  13. Surgical treatment of tricuspid regurgitation after mitral valve surgery: a retrospective study in China

    Directory of Open Access Journals (Sweden)

    Li Zong-Xiao

    2012-04-01

    Full Text Available Abstract Background Functional tricuspid regurgitation (TR occurs in patients with rheumatic mitral valve disease even after mitral valve surgery. The aim of this study was to analyze surgical results of TR after previous successful mitral valve surgery. Methods From September 1996 to September 2008, 45 patients with TR after previous mitral valve replacement underwent second operation for TR. In those, 43 patients (95.6% had right heart failure symptoms (edema of lower extremities, ascites, hepatic congestion, etc. and 40 patients (88.9% had atrial fibrillation. Twenty-six patients (57.8% were in New York Heart Association (NYHA functional class III, and 19 (42.2% in class IV. Previous operations included: 41 for mechanical mitral valve replacement (91.1%, 4 for bioprosthetic mitral valve replacement (8.9%, and 7 for tricuspid annuloplasty (15.6%. Results The tricuspid valves were repaired with Kay's (7 cases, 15.6% or De Vega technique (4 cases, 8.9%. Tricuspid valve replacement was performed in 34 cases (75.6%. One patient (2.2% died. Postoperative low cardiac output (LCO occurred in 5 patients and treated successfully. Postoperative echocardiography showed obvious reduction of right atrium and ventricle. The anterioposterior diameter of the right ventricle decreased to 25.5 ± 7.1 mm from 33.7 ± 6.2 mm preoperatively (P Conclusion TR after mitral valve replacement in rheumatic heart disease is a serious clinical problem. If it occurs or progresses late after mitral valve surgery, tricuspid valve annuloplasty or replacement may be performed with satisfactory results. Due to the serious consequence of untreated TR, aggressive treatment of existing TR during mitral valve surgery is recommended.

  14. Acceptance and introduction of disruptive technologies - simple steps to build a fully functional pulmonary valved stent.

    Science.gov (United States)

    Huber, Christoph H; Marty, Bettina; von Segesser, Ludwig K

    2007-08-01

    Valved stents are new land for cardiac surgeons even though they are being used more frequently by interventional disciplines. This paper presents simple steps to build a patient-specific pulmonary valved stent and its delivery device. The design concept was tested by random participants at a med-tech meeting. The valved stent is constructed by linking an endoprosthetic graft with a valved-jugular-vein. The delivery device is made from a modified 5-ml syringe. Of 72 participants, 66 (92%) built and 60 participants implanted the device successfully into the targeted pulmonary position via a trans-infundibular access.

  15. Experimental Validation of Modelled Fluid Forces in Fast Switching Hydraulic On/Off Valves

    DEFF Research Database (Denmark)

    Nørgård, Christian; Bech, Michael Møller; Roemer, Daniel Beck

    2015-01-01

    A prototype of a fast switching valve for a digital hydraulic machine has been designed and manufactured. The valve is composed of an annular seat plunger connected with a moving coil actuator as the force producing element. The valve prototype is designed for flow rates of 600 l/min with less than...... approaches the closed position. Fast switching is essential for digital hydraulic machines to achieve a high efficiency. As the fluid forces influences the response obtaining an accurate model is important. To validate the model tests are carried out on the prototype where the valve is closed, both...

  16. WAYS TO IMPROVE THE RELIABILITY AND OPERATING LIFE OF SMALL-SIZE ELECTROMAGNETIC VALVE

    Directory of Open Access Journals (Sweden)

    Gennadii Zaionchkovskyi

    2015-04-01

    Full Text Available This article considers the main ways of improving the reliability and durability of small-size electromagnetic valves. Major changes in the technical state of the valve components under dynamic operating loads were revealed using the results of resource tests of two-position valves with polarized electromagnetic actuator. Aneffective way for reducing the dynamic loads has proved to be the introduction of the damping element into the kinematic scheme of the electromagnetic valve actuator. Damping elements efficiency in reducing dynamic loads has been confirmed experimentally.

  17. Management of a locked Strata valve.

    Science.gov (United States)

    Bullivant, Kelly J; Mitha, Alim P; Hamilton, Mark G

    2009-04-01

    The PS Medical Strata valve is a programmable shunt valve used in the treatment of hydrocephalus that allows for noninvasive changes in the pressure setting using a magnet. The Strata valve is sensitive to magnetic fields, and reprogramming is frequently necessary after MR imaging. A known but rare complication of the Strata valve is that the rotor can become locked, causing shunt malfunction. This complication can only occur in a first generation Strata valve.

  18. 3D Printed Multimaterial Microfluidic Valve

    OpenAIRE

    Keating, Steven J.; Gariboldi, Maria Isabella; Patrick, William G.; Sharma, Sunanda; Kong, David S.; Oxman, Neri

    2016-01-01

    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 deform...

  19. The Screening Test for Emotional Problems--Teacher-Report Version (Step-T): Studies of Reliability and Validity

    Science.gov (United States)

    Erford, Bradley T.; Butler, Caitlin; Peacock, Elizabeth

    2015-01-01

    The Screening Test for Emotional Problems-Teacher Version (STEP-T) was designed to identify students aged 7-17 years with wide-ranging emotional disturbances. Coefficients alpha and test-retest reliability were adequate for all subscales except Anxiety. The hypothesized five-factor model fit the data very well and external aspects of validity were…

  20. Treatment of Aortic, Mitral and Tricuspid Structural Bioprosthetic Valve Deterioration Using the Valve-in-Valve Technique.

    Science.gov (United States)

    Codner, Pablo; Assali, Abid; Vaknin-Assa, Hana; Shapira, Yaron; Orvin, Katia; Sharony, Ram; Sagie, Alexander; Kornowski, Ran

    2015-05-01

    The percutaneous approach for a failed bioprosthetic valve is an emerging alternative to redo-valve surgery in patients at high surgical risk. The study aim was to describe the treatment of patients with structural bioprosthetic valve deterioration, using the valve-in-valve technique. A total of 33 consecutive patients with symptomatic structural bioprosthetic valve deterioration was treated at the authors' institution, using the valve-in-valve technique. The valve-in-valve procedure in the aortic position was performed in 23 patients (mean age 81.4 ± 5.9 years; mean STS score 9.6 ± 5.4). The self-expandable and balloon-expandable devices were used in 21 cases (91.3%) and two cases (8.7%), respectively. Procedures were performed via the trans-femoral, trans-axillary and trans-apical routes in 18 (78.2%), three (13%) and two (8.7%) cases, respectively. After the procedure, all patients were in NYHA class I/II. Survival rates were 95.6% at the one-year follow up. The valve-in-valve procedure in the mitral position was performed in 10 patients (mean age 73.6 ± 15 years; mean STS score 7.7 ± 4.1). All procedures were performed using the balloon-expandable device via the trans-apical route. The composite end point of device success was achieved in all patients. Survival rates were 100% and 75% at one month and two years' follow up, respectively. A single valve-in-valve implantation within a failed tricuspid bioprosthetic valve was also successfully performed. In the authors' experience, the valve-in-valve technique for the treatment of a wide range of bioprosthetic valve deterioration modes of failure in different valve positions is safe and very effective.

  1. Neurotrophin 3 upregulates proliferation and collagen production in human aortic valve interstitial cells: a potential role in aortic valve sclerosis.

    Science.gov (United States)

    Yao, Qingzhou; Song, Rui; Ao, Lihua; Cleveland, Joseph C; Fullerton, David A; Meng, Xianzhong

    2017-06-01

    Calcific aortic valve disease (CAVD) is a leading cardiovascular disorder in the elderly. Diseased aortic valves are characterized by sclerosis (fibrosis) and nodular calcification. Sclerosis, an early pathological change, is caused by aortic valve interstitial cell (AVIC) proliferation and overproduction of extracellular matrix (ECM) proteins. However, the mechanism of aortic valve sclerosis remains unclear. Recently, we observed that diseased human aortic valves overexpress growth factor neurotrophin 3 (NT3). In the present study, we tested the hypothesis that NT3 is a profibrogenic factor to human AVICs. AVICs isolated from normal human aortic valves were cultured in M199 growth medium and treated with recombinant human NT3 (0.10 µg/ml). An exposure to NT3 induced AVIC proliferation, upregulated the production of collagen and matrix metalloproteinase (MMP), and augmented collagen deposition. These changes were abolished by inhibition of the Trk receptors. NT3 induced Akt phosphorylation and increased cyclin D1 protein levels in a Trk receptor-dependent fashion. Inhibition of Akt abrogated the effect of NT3 on cyclin D1 production. Furthermore, inhibition of either Akt or cyclin D1 suppressed NT3-induced cellular proliferation and MMP-9 and collagen production, as well as collagen deposition. Thus, NT3 upregulates cellular proliferation, ECM protein production, and collagen deposition in human AVICs. It exerts these effects through the Trk-Akt-cyclin D1 cascade. NT3 is a profibrogenic mediator in human aortic valve, and overproduction of NT3 by aortic valve tissue may contribute to the mechanism of valvular sclerosis. Copyright © 2017 the American Physiological Society.

  2. Adapting tests of sign language assessment for other sign languages--a review of linguistic, cultural, and psychometric problems.

    Science.gov (United States)

    Haug, Tobias; Mann, Wolfgang

    2008-01-01

    Given the current lack of appropriate assessment tools for measuring deaf children's sign language skills, many test developers have used existing tests of other sign languages as templates to measure the sign language used by deaf people in their country. This article discusses factors that may influence the adaptation of assessment tests from one natural sign language to another. Two tests which have been adapted for several other sign languages are focused upon: the Test for American Sign Language and the British Sign Language Receptive Skills Test. A brief description is given of each test as well as insights from ongoing adaptations of these tests for other sign languages. The problems reported in these adaptations were found to be grounded in linguistic and cultural differences, which need to be considered for future test adaptations. Other reported shortcomings of test adaptation are related to the question of how well psychometric measures transfer from one instrument to another.

  3. Towards risk-based test protocols: estimating the contribution of intensive testing to the UK bovine tuberculosis problem.

    Directory of Open Access Journals (Sweden)

    Jan van Dijk

    Full Text Available Eradicating disease from livestock populations involves the balancing act of removing sufficient numbers of diseased animals without removing too many healthy individuals in the process. As ever more tests for bovine tuberculosis (BTB are carried out on the UK cattle herd, and each positive herd test triggers more testing, the question arises whether 'false positive' results contribute significantly to the measured BTB prevalence. Here, this question is explored using simple probabilistic models of test behaviour. When the screening test is applied to the average UK herd, the estimated proportion of test-associated false positive new outbreaks is highly sensitive to small fluctuations in screening test specificity. Estimations of this parameter should be updated as a priority. Once outbreaks have been confirmed in screening-test positive herds, the following rounds of intensive testing with more sensitive, albeit less specific, tests are highly likely to remove large numbers of false positive animals from herds. Despite this, it is unlikely that significantly more truly infected animals are removed. BTB test protocols should become based on quantified risk in order to prevent the needless slaughter of large numbers of healthy animals.

  4. Towards risk-based test protocols: estimating the contribution of intensive testing to the UK bovine tuberculosis problem.

    Science.gov (United States)

    van Dijk, Jan

    2013-01-01

    Eradicating disease from livestock populations involves the balancing act of removing sufficient numbers of diseased animals without removing too many healthy individuals in the process. As ever more tests for bovine tuberculosis (BTB) are carried out on the UK cattle herd, and each positive herd test triggers more testing, the question arises whether 'false positive' results contribute significantly to the measured BTB prevalence. Here, this question is explored using simple probabilistic models of test behaviour. When the screening test is applied to the average UK herd, the estimated proportion of test-associated false positive new outbreaks is highly sensitive to small fluctuations in screening test specificity. Estimations of this parameter should be updated as a priority. Once outbreaks have been confirmed in screening-test positive herds, the following rounds of intensive testing with more sensitive, albeit less specific, tests are highly likely to remove large numbers of false positive animals from herds. Despite this, it is unlikely that significantly more truly infected animals are removed. BTB test protocols should become based on quantified risk in order to prevent the needless slaughter of large numbers of healthy animals.

  5. The students’ ability in mathematical literacy for the quantity, and the change and relationship problems on the PISA adaptation test

    Science.gov (United States)

    Julie, Hongki; Sanjaya, Febi; Yudhi Anggoro, Ant.

    2017-09-01

    One of purposes of this study was to describe the solution profile of the junior high school students for the PISA adaptation test. The procedures conducted by researchers to achieve this objective were (1) adapting the PISA test, (2) validating the adapting PISA test, (3) asking junior high school students to do the adapting PISA test, and (4) making the students’ solution profile. The PISA problems for mathematics could be classified into four areas, namely quantity, space and shape, change and relationship, and uncertainty. The research results that would be presented in this paper were the result test for quantity, and change and relationship problems. In the adapting PISA test, there were fifteen questions that consist of two questions for the quantity group, six questions for space and shape group, three questions for the change and relationship group, and four questions for uncertainty. Subjects in this study were 18 students from 11 junior high schools in Yogyakarta, Central Java, and Banten. The type of research that used by the researchers was a qualitative research. For the first quantity problem, there were 38.89 % students who achieved level 3. For the second quantity problem, there were 88.89 % students who achieved level 2. For part a of the first change and relationship problem, there were 55.56 % students who achieved level 5. For part b of the first change and relationship problem, there were 77.78 % students who achieved level 2. For the second change and relationship problem, there were 38.89 % students who achieved level 2.

  6. The Association Between Conduct Problems and Maltreatment: Testing Genetic and Environmental Mediation

    OpenAIRE

    Schulz-Heik, R. Jay; Rhee, Soo Hyun; Silvern, Louise E.; Haberstick, Brett C.; Hopfer, Christian; Lessem, Jeffrey M.; Hewitt, John K.

    2009-01-01

    It is often assumed that childhood maltreatment causes conduct problems via an environmentally mediated process. However, the association may be due alternatively to either a nonpassive gene-environment correlation, in which parents react to children’s genetically-influenced conduct problems by maltreating them, or a passive gene-environment correlation, in which parents’ tendency to engage in maltreatment and children’s conduct problems are both influenced by a hereditary vulnerability to an...

  7. 3D printed mitral valve models: affordable simulation for robotic mitral valve repair.

    Science.gov (United States)

    Premyodhin, Ned; Mandair, Divneet; Ferng, Alice S; Leach, Timothy S; Palsma, Ryan P; Albanna, Mohammad Z; Khalpey, Zain I

    2018-01-01

    3D printed mitral valve (MV) models that capture the suture response of real tissue may be utilized as surgical training tools. Leveraging clinical imaging modalities, 3D computerized modelling and 3D printing technology to produce affordable models complements currently available virtual simulators and paves the way for patient- and pathology-specific preoperative rehearsal. We used polyvinyl alcohol, a dissolvable thermoplastic, to 3D print moulds that were casted with liquid platinum-cure silicone yielding flexible, low-cost MV models capable of simulating valvular tissue. Silicone-moulded MV models were fabricated for 2 morphologies: the normal MV and the P2 flail. The moulded valves were plication and suture tested in a laparoscopic trainer box with a da Vinci Si robotic surgical system. One cardiothoracic surgery fellow and 1 attending surgeon qualitatively evaluated the ability of the valves to recapitulate tissue feel through surveys utilizing the 5-point Likert-type scale to grade impressions of the valves. Valves produced with the moulding and casting method maintained anatomical dimensions within 3% of directly 3D printed acrylonitrile butadiene styrene controls for both morphologies. Likert-type scale mean scores corresponded with a realistic material response to sutures (5.0/5), tensile strength that is similar to real MV tissue (5.0/5) and anatomical appearance resembling real MVs (5.0/5), indicating that evaluators 'agreed' that these aspects of the model were appropriate for training. Evaluators 'somewhat agreed' that the overall model durability was appropriate for training (4.0/5) due to the mounting design. Qualitative differences in repair quality were notable between fellow and attending surgeon. 3D computer-aided design, 3D printing and fabrication techniques can be applied to fabricate affordable, high-quality educational models for technical training that are capable of differentiating proficiency levels among users.

  8. Is Trait Rumination Associated with the Ability to Generate Effective Problem Solving Strategies? Utilizing Two Versions of the Means-Ends Problem-Solving Test.

    Science.gov (United States)

    Hasegawa, Akira; Nishimura, Haruki; Mastuda, Yuko; Kunisato, Yoshihiko; Morimoto, Hiroshi; Adachi, Masaki

    This study examined the relationship between trait rumination and the effectiveness of problem solving strategies as assessed by the Means-Ends Problem-Solving Test (MEPS) in a nonclinical population. The present study extended previous studies in terms of using two instructions in the MEPS: the second-person, actual strategy instructions, which has been utilized in previous studies on rumination, and the third-person, ideal-strategy instructions, which is considered more suitable for assessing the effectiveness of problem solving strategies. We also replicated the association between rumination and each dimension of the Social Problem-Solving Inventory-Revised Short Version (SPSI-R:S). Japanese undergraduate students (N = 223) completed the Beck Depression Inventory-Second Edition, Ruminative Responses Scale (RRS), MEPS, and SPSI-R:S. One half of the sample completed the MEPS with the second-person, actual strategy instructions. The other participants completed the MEPS with the third-person, ideal-strategy instructions. The results showed that neither total RRS score, nor its subscale scores were significantly correlated with MEPS scores under either of the two instructions. These findings taken together with previous findings indicate that in nonclinical populations, trait rumination is not related to the effectiveness of problem solving strategies, but that state rumination while responding to the MEPS deteriorates the quality of strategies. The correlations between RRS and SPSI-R:S scores indicated that trait rumination in general, and its brooding subcomponent in particular are parts of cognitive and behavioral responses that attempt to avoid negative environmental and negative private events. Results also showed that reflection is a part of active problem solving.

  9. Evaluating All-Metal Valves for Use in a Tritium Environment

    Energy Technology Data Exchange (ETDEWEB)

    Houk, L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Payton, A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-28

    In the tritium gas processing system, it is desired to minimize polymer components due to their degradation from tritium exposure (beta decay). One source of polymers in the tritium process is valve components. A vendor has been identified that manufactures a valve that is marketed as being made from all-metal construction. This manufacturer, Ham-Let Group, manufactures a diaphragm valve (3LE series) that claims to be made entirely of metal. SRNL procured twelve (12) Ham-Let diaphragm valves for characterization and evaluation. The characterization tests include identification of the maximum pressure of these valves by performing pressure and burst tests. Leak tests were performed to ensure the valves do not exceed the acceptable leak rate for tritium service. These valves were then cycled in a nitrogen gas and/or vacuum environment to ensure they would be durable in a process environment. They were subsequently leak tested per ASTM protocol to ensure that the valves maintained their leak tight integrity. A detailed material analysis was also conducted to determine hydrogen and tritium compatibility.

  10. Lipomatosis and true lipomas of the ileocecal valve

    Energy Technology Data Exchange (ETDEWEB)

    Skaane, P.; Eide, T.J.; Westgaard, T.; Gauperaa, T.

    1981-12-01

    Two patients with lipomatosis and two patients with true lipoma of the ileocecal valve are described. The symptomatology, radiological appearances, pathological findings and treatment are discussed. True lipomas of the ileocecal valve should be differentiated from the more commonly occurring lipomatosis or lipohyperplasia. The rare true lipomas have a demarcating capsule around the fatty tissue and are confined to only one of the ileocecal lips. The lipomatosis, on the other hand, is characterized by a diffuse fatty deposition in the submucosa of the valve with no encapsulation. Lipomatosis as well as true lipomas may appear as rounded, smoothly outlined and sharply demarcated masses on barium enema examination. Occasionally, these filling defects may present problems of differential diagnosis with respect to malignant involvement of the ileocecal region. A correct preoperative diagnosis, however, is important to prevent unnecessary or too radical surgical treatment.

  11. A comprehensive longitudinal test of the acquired preparedness model for alcohol use and related problems.

    Science.gov (United States)

    Corbin, William R; Iwamoto, Derek K; Fromme, Kim

    2011-07-01

    According to the acquired preparedness model (APM), personality traits related to disinhibition (i.e., impulsivity and sensation seeking) may influence the learning process, contributing to individual differences in cognitions (e.g., expectations about outcomes) that may contribute to engagement in and consequences of risk behaviors, including alcohol use. Although there is strong support for the APM, longitudinal studies have involved short-term follow-ups, and the relevance of the APM for alcohol-related consequences has not been clearly established. Participants were 2,245 (59.9% female) incoming freshmen who completed the first of eight web-based surveys during the summer before college matriculation. Structural equation modeling was used to test a comprehensive longitudinal APM for both alcohol use and related consequences. Multigroup models were used to examine measurement and structural invariance by gender. Positive (but not negative) alcohol expectancies during freshman year of college partially mediated the relation between senior year of high school disinhibition and both alcohol use and related problems during the fourth year of college, and multigroup models suggested that the relationships proposed in the APM operated similarly for women and men. This study demonstrates the temporal relations proposed in the APM across a longer period (4 years) than in previous studies among a large sample of ethnically diverse students. Further, the results are the first to validate the APM with respect to drinking consequences while controlling for levels of alcohol use. The results lend support for brief interventions targeting positive alcohol expectancies, particularly for individuals high in trait disinhibition.

  12. Compliant topology optimization for planar passive flap micro valve.

    Science.gov (United States)

    Yoon, Gil Ho

    2014-10-01

    This paper reports the compliant topology optimization for planar passive flap micro valve considering fluid-structure interaction with a monolithic approach. Although flap valve type check valve is easy to manufacture and use for the applications for Bio/Nano/MEMS, its structural optimization has been seldom conducted so far. The size of the Bio/Nano/MEMS devices becomes smaller and the simple straight type micro valve structure is required to be optimized considering fluid speed. To address this optimization problem, the structural topology optimization scheme which designs optimal topologies is applied for a flap type check valve structure. To consider the coupling effects of fluid domain and structural domain, the monolithic finite element approach is employed. In the new analysis approach, solid domain is simulated by introducing the inverse permeability in the Navier-Stokes equation and the fluid stress filter in the linear elasticity equation. Also it is a new idea that fluid domain is simulated by finite elements with a weak Young's modulus in the linear elasticity equation. The mutual couplings between fluid and structure are considered by the introduction of the deformation tensor which is one of the basic concepts of the continuum mechanism. By distributing material properties inside a design domain for compliant flap, optimal flap structures can be constructed with different fluid speeds. By investigating the optimal layouts of several passive flap designs, we prove that the structural topology optimization can provide optimal layouts for Bio, Nano, and MEMS applications.

  13. The association between conduct problems and maltreatment: testing genetic and environmental mediation.

    Science.gov (United States)

    Schulz-Heik, R Jay; Rhee, Soo Hyun; Silvern, Louise E; Haberstick, Brett C; Hopfer, Christian; Lessem, Jeffrey M; Hewitt, John K

    2010-05-01

    It is often assumed that childhood maltreatment causes conduct problems via an environmentally mediated process. However, the association may be due alternatively to either a nonpassive gene-environment correlation, in which parents react to children's genetically-influenced conduct problems by maltreating them, or a passive gene-environment correlation, in which parents' tendency to engage in maltreatment and children's conduct problems are both influenced by a hereditary vulnerability to antisocial behavior (i.e. genetic mediation). The present study estimated the contribution of these processes to the association between maltreatment and conduct problems. Bivariate behavior genetic analyses were conducted on approximately 1,650 twin and sibling pairs drawn from a large longitudinal study of adolescent health (Add Health). The correlation between maltreatment and conduct problems was small; much of the association between maltreatment and conduct problems was due to a nonpassive gene-environment correlation. Results were more consistent with the hypothesis that parents respond to children's genetically-influenced conduct problems by maltreating them than the hypothesis that maltreatment causes conduct problems.

  14. An accurate and efficient identification of children with psychosocial problems by means of computerized adaptive testing

    NARCIS (Netherlands)

    Vogels, Antonius G. C.; Jacobusse, Gert W.; Reijneveld, Symen A.

    2011-01-01

    Background: Questionnaires used by health services to identify children with psychosocial problems are often rather short. The psychometric properties of such short questionnaires are mostly less than needed for an accurate distinction between children with and without problems. We aimed to assess

  15. Transcatheter Replacement of Failed Bioprosthetic Valves

    DEFF Research Database (Denmark)

    Simonato, Matheus; Webb, John; Kornowski, Ran

    2016-01-01

    valve mechanism of failure (stenosis/mixed baseline failure: odds ratio, 3.12; confidence interval, 1.51-6.45; P=0.002). Conclusions-High implantation inside failed bioprosthetic valves is a strong independent correlate of lower postprocedural gradients in both self-and balloon-expandable transcatheter......Background-Transcatheter valve implantation inside failed bioprosthetic surgical valves (valve-in-valve [ViV]) may offer an advantage over reoperation. Supra-annular transcatheter valve position may be advantageous in achieving better hemodynamics after ViV. Our objective was to define targets...... for implantation that would improve hemodynamics after ViV. Methods and Results-Cases from the Valve-in-Valve International Data (VIVID) registry were analyzed using centralized core laboratory assessment blinded to clinical events. Multivariate analysis was performed to identify independent predictors of elevated...

  16. Discontinuous Petrov-Galerkin method based on the optimal test space norm for steady transport problems in one space dimension

    KAUST Repository

    Niemi, Antti

    2013-05-01

    We revisit the finite element analysis of convection-dominated flow problems within the recently developed Discontinuous Petrov-Galerkin (DPG) variational framework. We demonstrate how test function spaces that guarantee numerical stability can be computed automatically with respect to the optimal test space norm. This makes the DPG method not only stable but also robust, that is, uniformly stable with respect to the Péclet number in the current application. We employ discontinuous piecewise Bernstein polynomials as trial functions and construct a subgrid discretization that accounts for the singular perturbation character of the problem to resolve the corresponding optimal test functions. We also show that a smooth B-spline basis has certain computational advantages in the subgrid discretization. The overall effectiveness of the algorithm is demonstrated on two problems for the linear advection-diffusion equation. © 2011 Elsevier B.V.

  17. Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

    Science.gov (United States)

    Ramaswamy, Sharan; Salinas, Manuel; Carrol, Rob; Landaburo, Karla; Ryans, Xavier; Crespo, Cynthia; Rivero, Ailyn; Al-Mousily, Faris; DeGroff, Curt; Bleiweis, Mark; Yamaguchi, Hitomi

    2013-01-01

    Limitations of currently available prosthetic valves, xenografts, and homografts have prompted a recent resurgence of developments in the area of tri-leaflet polymer valve prostheses. However, identification of a protocol for initial assessment of polymer valve hydrodynamic functionality is paramount during the early stages of the design process. Traditional in vitro pulse duplicator systems are not configured to accommodate flexible tri-leaflet materials; in addition, assessment of polymer valve functionality needs to be made in a relative context to native and prosthetic heart valves under identical test conditions so that variability in measurements from different instruments can be avoided. Accordingly, we conducted hydrodynamic assessment of i) native (n = 4, mean diameter, D = 20 mm), ii) bi-leaflet mechanical (n= 2, D = 23 mm) and iii) polymer valves (n = 5, D = 22 mm) via the use of a commercially available pulse duplicator system (ViVitro Labs Inc, Victoria, BC) that was modified to accommodate tri-leaflet valve geometries. Tri-leaflet silicone valves developed at the University of Florida comprised the polymer valve group. A mixture in the ratio of 35:65 glycerin to water was used to mimic blood physical properties. Instantaneous flow rate was measured at the interface of the left ventricle and aortic units while pressure was recorded at the ventricular and aortic positions. Bi-leaflet and native valve data from the literature was used to validate flow and pressure readings. The following hydrodynamic metrics were reported: forward flow pressure drop, aortic root mean square forward flow rate, aortic closing, leakage and regurgitant volume, transaortic closing, leakage, and total energy losses. Representative results indicated that hydrodynamic metrics from the three valve groups could be successfully obtained by incorporating a custom-built assembly into a commercially available pulse duplicator system and subsequently, objectively compared to provide

  18. The use of check valve performance data to support new concepts (probabilistic risk assessment, condition monitoring) for check valve program

    Energy Technology Data Exchange (ETDEWEB)

    Hart, K.A.; Gower, D.

    1996-12-01

    The concept of developing an integrated check valve database based on the Nuclear Power Reliability Data System (NPRDS) data was presented at the last Symposium. The Nuclear Industry Check Valve Group (NIC), working in cooperation with the Oak Ridge National Laboratory (ORNL), has completed an operational database of check valve performance from 1984 to the present. NIC has committed to the nuclear industry to periodically update the data and maintain this information accessible. As the new concepts of probabilistic risk analysis and condition monitoring are integrated into the American Society of Mechanical Engineers (ASME) Code, a critical element will be performance data. From check valve performance data, feasible failure modes and rates can be established. When a failure rate or frequency of failures can be established based on a significant enough population (sampling), a more solid foundation for focusing resources and determining appropriate frequencies and testing can be determined. The presentation will give the updated status of the NIC Check Valve Performance Database covering (1) methodology used to combine the original ORNL data; (2) process/controls established for continuing update and refinement of the data; (3) discussion of how this data is being utilized by (a) OM-22 for condition monitoring, and (b) risk-based inservice testing work of Westinghouse Owners` Group; and (4) results/trends of data evaluations. At the 1994 Symposium, ORNL provided an update as of 1991 to their original work of 1984 -1990 which they had performed to characterize check valve degradations and failures in the nuclear industry. These characterizations will be updated to 1995 and additional reviews provided to give insight into the current condition and trends of check valve performance.

  19. Heart valve scaffold fabrication: Bioinspired control of macro-scale morphology, mechanics and micro-structure.

    Science.gov (United States)

    D'Amore, Antonio; Luketich, Samuel K; Raffa, Giuseppe M; Olia, Salim; Menallo, Giorgio; Mazzola, Antonino; D'Accardi, Flavio; Grunberg, Tamir; Gu, Xinzhu; Pilato, Michele; Kameneva, Marina V; Badhwar, Vinay; Wagner, William R

    2018-01-01

    Valvular heart disease is currently treated with mechanical valves, which benefit from longevity, but are burdened by chronic anticoagulation therapy, or with bioprosthetic valves, which have reduced thromboembolic risk, but limited durability. Tissue engineered heart valves have been proposed to resolve these issues by implanting a scaffold that is replaced by endogenous growth, leaving autologous, functional leaflets that would putatively eliminate the need for anticoagulation and avoid calcification. Despite the diversity in fabrication strategies and encouraging results in large animal models, control over engineered valve structure-function remains at best partial. This study aimed to overcome these limitations by introducing double component deposition (DCD), an electrodeposition technique that employs multi-phase electrodes to dictate valve macro and microstructure and resultant function. Results in this report demonstrate the capacity of the DCD method to simultaneously control scaffold macro-scale morphology, mechanics and microstructure while producing fully assembled stent-less multi-leaflet valves composed of microscopic fibers. DCD engineered valve characterization included: leaflet thickness, biaxial properties, bending properties, and quantitative structural analysis of multi-photon and scanning electron micrographs. Quasi-static ex-vivo valve coaptation testing and dynamic organ level functional assessment in a pressure pulse duplicating device demonstrated appropriate acute valve functionality. Copyright © 2017. Published by Elsevier Ltd.

  20. The neural correlates of problem states: testing FMRI predictions of a computational model of multitasking.

    Directory of Open Access Journals (Sweden)

    Jelmer P Borst

    Full Text Available BACKGROUND: It has been shown that people can only maintain one problem state, or intermediate mental representation, at a time. When more than one problem state is required, for example in multitasking, performance decreases considerably. This effect has been explained in terms of a problem state bottleneck. METHODOLOGY: In the current study we use the complimentary methodologies of computational cognitive modeling and neuroimaging to investigate the neural correlates of this problem state bottleneck. In particular, an existing computational cognitive model was used to generate a priori fMRI predictions for a multitasking experiment in which the problem state bottleneck plays a major role. Hemodynamic responses were predicted for five brain regions, corresponding to five cognitive resources in the model. Most importantly, we predicted the intraparietal sulcus to show a strong effect of the problem state manipulations. CONCLUSIONS: Some of the predictions were confirmed by a subsequent fMRI experiment, while others were not matched by the data. The experiment supported the hypothesis that the problem state bottleneck is a plausible cause of the interference in the experiment and that it could be located in the intraparietal sulcus.

  1. Discontinuous Petrov-Galerkin method based on the optimal test space norm for one-dimensional transport problems

    KAUST Repository

    Niemi, Antti

    2011-05-14

    We revisit the finite element analysis of convection dominated flow problems within the recently developed Discontinuous Petrov-Galerkin (DPG) variational framework. We demonstrate how test function spaces that guarantee numerical stability can be computed automatically with respect to the so called optimal test space norm by using an element subgrid discretization. This should make the DPG method not only stable but also robust, that is, uniformly stable with respect to the Ṕeclet number in the current application. The e_ectiveness of the algorithm is demonstrated on two problems for the linear advection-di_usion equation.

  2. Persistent radiographic cone cuts: a simple test to avoid the frustrating problem.

    Science.gov (United States)

    Shivanandappa, Santosh Gowdru; Mushannavar, Lata Shankarappa; Katti, Girish

    2014-01-01

    In routine dental radiography, one may encounter numerous radiographic errors, one of which may be partial images or cone cuts. These cones cut errors although may appear as simple problems, but often persistent cone cuts may be frustrating to the dental practitioner. In this study, our main aim was to find and solve the origin of the problem. This study was conducted with two different intraoral X-ray machines with 12 inch length position indicating devices (PIDs) with four No. 2 intraoral films. If the problem is originated in the X-ray machine, it can be solved by either tapping the collimator or by repositioning the PID.

  3. Persistent radiographic cone cuts: A simple test to avoid the frustrating problem

    Directory of Open Access Journals (Sweden)

    Santosh Gowdru Shivanandappa

    2014-01-01

    Full Text Available In routine dental radiography, one may encounter numerous radiographic errors, one of which may be partial images or cone cuts. These cones cut errors although may appear as simple problems, but often persistent cone cuts may be frustrating to the dental practitioner. In this study, our main aim was to find and solve the origin of the problem. This study was conducted with two different intraoral X-ray machines with 12 inch length position indicating devices (PIDs with four No. 2 intraoral films. If the problem is originated in the X-ray machine, it can be solved by either tapping the collimator or by repositioning the PID.

  4. Sutureless Valves Reduce Hospital Costs Compared to Traditional Valves.

    Science.gov (United States)

    Laborde, François; Folliguet, Thierry; Ghorayeb, Gabriel; Zannis, Konstantinos

    2017-01-01

    The study aim was to assess differences in clinical outcome, safety, and associated costs between sutureless and aortic isolated aortic valve replacement (AVR) with a standard bioprosthesis. A retrospective comparative study was conducted to investigate 65 patients, each of whom had undergone isolated AVR with a traditional aortic valve (T) or a Perceval S sutureless aortic prosthesis (P) between January 2010 and December 2012. Cost data were drawn from the proprietary cost accounting system of the hospital, excluding acquisition costs of the devices. A linear regression model was used to estimate the mean total costs difference between groups. The mean cardiopulmonary bypass time and aortic cross-clamp times in the T and P groups were 80 ± 41 min and 58 ± 26 min versus 38 ± 16 min and 26 ± 10 min, respectively (p costs savings for group P compared to group T were €3,801 (p = 0.13), mainly driven by hospital stay costs. Savings between the P and T groups increased with age: €4,992 in patients aged 70-79 years and €9,326 in those aged 80+ years, and with risk (€4,296 for high-risk patients). Sutureless aortic valves present shorter procedural times and lower hospital costs compared to traditional valves, with higher cost savings at increased patient age and risk. Sutureless aortic valves seem to be cost-effective in patients undergoing AVR.

  5. Numerical simulation on a throttle governing system with hydraulic butterfly valves in a marine environment

    Science.gov (United States)

    Wan, Hui-Xiong; Fang, Jun; Huang, Hui

    2010-12-01

    Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems resulting from switching angular speeds of the hydraulic butterfly valve, a throttle-governing control mode has been widely adopted, and detailed analysis has been carried out worldwide on the structural principle concerning speed-regulation and the load torque on the shaft while opening or closing a hydraulic butterfly valve. However relevant reports have yet been published on the change law, the error and the influencing factors of the rotational angular velocity of the hydraulic butterfly valve while opening and closing. In this article, research was based on some common specifications of a hydraulic butterfly valve with a symmetrical valve flap existing in a marine environment. The throttle governing system supplied by the accumulator to achieve the switching of the hydraulic control valve was adopted, and the mathematical models of the system were established in the actual conditions while the numerical simulations took place. The simulation results and analysis show that the rotational angular velocity and the error of the hydraulic butterfly valve while switching is influenced greatly by the drainage amount of the accumulator, resulting in pressure loss in the pipeline, the temperature of hydraulic medium and the load of the hydraulic butterfly valve. The simulation results and analysis provide a theoretical basis for the choice of the total capacity of the accumulator and pipeline diameters in a throttle governing system with a hydraulic butterfly valve. It also determines the type and specification of the hydraulic butterfly valve and the design of motion parameters of the transported fluid.

  6. Robotically assisted mitral valve replacement.

    Science.gov (United States)

    Gao, Changqing; Yang, Ming; Xiao, Cangsong; Wang, Gang; Wu, Yang; Wang, Jiali; Li, Jiachun

    2012-04-01

    In the present study, we determined the safety and efficacy of robotic mitral valve replacement using robotic technology. From January 2007 through March 2011, more than 400 patients underwent various types of robotic cardiac surgery in our department. Of these, 22 consecutive patients underwent robotically assisted mitral valve replacement. Of the 22 patients with isolated rheumatic mitral valve stenosis (9 men and 13 women), the mean age was 44.7 ± 19.8 years (range, 32-65). Preoperatively, all patients underwent a complete workup, including coronary angiography and transthoracic echocardiography. Of the 22 patients, 15 had concomitant atrial fibrillation. The surgical approach was through 4 right-side chest ports with femoral perfusion. Aortic occlusion was performed with a Chitwood crossclamp, and antegrade cardioplegia was administered directly by way of the anterior chest. Using 3 port incisions in the right side of the chest and a 2.5- to 3.0-cm working port, all the procedures were completed with the da Vinci S robot. All patients underwent successful robotic surgery. Of the 22 patients, 16 received a mechanical valve and 6 a tissue valve. The mean cardiopulmonary bypass time and aortic crossclamp time was 137.1 ± 21.9 minutes (range, 105-168) and 99.3 ± 17.9 minutes (range, 80-133), respectively. No operative deaths, stroke, or other complications occurred, and no incisional conversions were required. After surgery, all the patients were followed up echocardiographically. Robotically assisted mitral valve replacement can be performed safely in patients with isolated mitral valve stenosis, and surgical results are excellent. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  7. What Are the Signs and Symptoms of Heart Valve Disease?

    Science.gov (United States)

    ... as well as surgery for adults who have aortic valve stenosis. Doctors often use balloon valvuloplasty to repair valve stenosis in infants and children. Replacing Heart Valves Sometimes heart valves can’t ...

  8. The Effect of Test Anxiety, Intelligence, and Sex on Children's Problem Solving Ability

    Science.gov (United States)

    Doyal, Guy T.; Forsyth, Robert A.

    1972-01-01

    Results indicated that the anxiety treatment in this study was not significantly related to level of intelligence; a significant Sex by Anxiety interaction for both simple and complex problem solving was indicated. (Authors/CB)

  9. FLAG Simulations of the Elasticity Test Problem of Gavrilyuk et al.

    Energy Technology Data Exchange (ETDEWEB)

    Kamm, James R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Runnels, Scott R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Canfield, Thomas R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carney, Theodore C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-04-23

    This report contains a description of the impact problem used to compare hypoelastic and hyperelastic material models, as described by Gavrilyuk, Favrie & Saurel. That description is used to set up hypoelastic simulations in the FLAG hydrocode.

  10. Design and development of a leak tight helium II valve with low thermal impact

    Science.gov (United States)

    Mills, G. L.

    1991-01-01

    The Lambda Point Experiment is a precision measurement of the specific heat of liquid helium near the lambda point phase transition, in the low gravity of the space shuttle. It requires a valve for the helium sample chamber that operates at helium II temperature, has minimal thermal disturbance to the rest of the instrument, and is leak tight to helium II. A valve meeting these and all of the other science and engineering requirements of the mission has been developed by Ball. Initially, both torque and pressure actuated valve concepts were considered; the final flight design is pressure actuated. The rational for this decision as well as the rest of the valve design are given. The paper also discusses the manufacturing and testing of the prototype and flight valves. Test data is presented and discussed.

  11. Clinical review: Endobronchial valve treatment for emphysema.

    Science.gov (United States)

    Jarad, Nabil

    2016-05-01

    Breathlessness and impaired quality of life are prominent features in patients with severe emphysema even when conventional methods of treatment are optimal. Lung volume reduction using endobronchial management for emphysema has emerged as a new method to relieve symptoms and improve lung function tests in this group. The endobronchial valves (EBVs) are the most widely used treatment. This article outlines current criteria of patients' selection with literature review and evidence of efficacy. Complications of EBV insertion as well as current shortfalls of this method of treatment are also discussed. © The Author(s) 2016.

  12. Pregnancy After Transcatheter Pulmonary Valve Implantation.

    Science.gov (United States)

    Kozicka, Urszula; Weroński, Krzysztof; Rużyłło, Witold; Demkow, Marcin; Kowalski, Mirosław; Śpiewak, Mateusz; Piotrowicz, Ewa; Siudalska, Hanna; Hoffman, Piotr; Biernacka, Elżbieta K

    2017-12-01

    Transcatheter pulmonary valve implantation (TPVI) is a relatively new method of treating patients with significant pulmonary regurgitation or pulmonary stenosis, or both, after reconstruction of the right ventricular outflow tract. It is an attractive alternative to conduit replacement in this group of patients, who are typically young and active. This report includes 4 young women who after successful TPVI became pregnant and gave birth. Transthoracic echocardiography, cardiopulmonary exercise testing, and cardiac magnetic resonance imaging were performed in all patients. The results suggest that pregnancy and delivery after successful TPVI is safe when the appropriate precautions have been taken. Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  13. Mitral valve aneurysm associated with aortic valve endocarditis and regurgitation.

    Science.gov (United States)

    Raval, Amish N; Menkis, Alan H; Boughner, Derek R

    2002-01-01

    Mitral valve aneurysms are rare complications occurring most commonly in association with aortic valve infective endocarditis. [Decroly 1989, Chua 1990, Northridge 1991, Karalis 1992, Roguin 1996, Mollod 1997, Vilacosta 1997, Cai 1999, Vilacosta 1999, Teskey 1999, Chan 2000, Goh 2000, Marcos- Alberca 2000] While the mechanism of the development of this lesion is unclear, complications such as perforation can occur and lead to significant mitral regurgitation. [Decroly 1989, Karalis 1992, Teskey 1999, Vilacosta 1999]; The case of a 69-year-old male with Streptococcus Sanguis aortic valve endocarditis and associated anterior mitral leaflet aneurysm is presented. Following surgery, tissue pathology of the excised lesion revealed myxomatous degeneration and no active endocarditis or inflammatory cells. This may add support to the hypothesis that physical stress due to severe aortic insufficiency and structural weakening, without infection of the anterior mitral leaflet, can lead to the development of this lesion.

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

    Science.gov (United States)

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

    2014-01-01

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

  15. Minimally Invasive Heart Valve Surgery.

    Science.gov (United States)

    Bouhout, Ismail; Morgant, Marie-Catherine; Bouchard, Denis

    2017-09-01

    Minimally invasive valve surgery represents a recent and significant advance in modern heart surgery. Indeed, many less invasive approaches for both the aortic and mitral valves have been developed in the past 2 decades. These procedures were hypothesized to result in less operative trauma, which might translate into better patient outcomes. However, this clinical benefit remains controversial in the literature. The aim of this review is to discuss the evidence surrounding minimally invasive heart valve surgery in the current era. A systematic search of the literature from 2006-2016 was performed looking for articles reporting early or late outcomes after minimally invasive valve surgery. Less invasive valve surgery is safe and provides long-term surgical outcomes similar to those of standard sternotomy. In addition, these approaches result in a reduction in overall hospital length of stay and may mitigate the risk of early morbidity-mainly postoperative bleeding, transfusions, and ventilation duration. Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  16. Summary of Documentation for DYNA3D-ParaDyn's Software Quality Assurance Regression Test Problems

    Energy Technology Data Exchange (ETDEWEB)

    Zywicz, Edward [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-08-18

    The Software Quality Assurance (SQA) regression test suite for DYNA3D (Zywicz and Lin, 2015) and ParaDyn (DeGroot, et al., 2015) currently contains approximately 600 problems divided into 21 suites, and is a required component of ParaDyn’s SQA plan (Ferencz and Oliver, 2013). The regression suite allows developers to ensure that software modifications do not unintentionally alter the code response. The entire regression suite is run prior to permanently incorporating any software modification or addition. When code modifications alter test problem results, the specific cause must be determined and fully understood before the software changes and revised test answers can be incorporated. The regression suite is executed on LLNL platforms using a Python script and an associated data file. The user specifies the DYNA3D or ParaDyn executable, number of processors to use, test problems to run, and other options to the script. The data file details how each problem and its answer extraction scripts are executed. For each problem in the regression suite there exists an input deck, an eight-processor partition file, an answer file, and various extraction scripts. These scripts assemble a temporary answer file in a specific format from the simulation results. The temporary and stored answer files are compared to a specific level of numerical precision, and when differences are detected the test problem is flagged as failed. Presently, numerical results are stored and compared to 16 digits. At this accuracy level different processor types, compilers, number of partitions, etc. impact the results to various degrees. Thus, for consistency purposes the regression suite is run with ParaDyn using 8 processors on machines with a specific processor type (currently the Intel Xeon E5530 processor). For non-parallel regression problems, i.e., the two XFEM problems, DYNA3D is used instead. When environments or platforms change, executables using the current source code and the new

  17. Automatically stable discontinuous Petrov-Galerkin methods for stationary transport problems: Quasi-optimal test space norm

    KAUST Repository

    Niemi, Antti H.

    2013-12-01

    We investigate the application of the discontinuous Petrov-Galerkin (DPG) finite element framework to stationary convection-diffusion problems. In particular, we demonstrate how the quasi-optimal test space norm improves the robustness of the DPG method with respect to vanishing diffusion. We numerically compare coarse-mesh accuracy of the approximation when using the quasi-optimal norm, the standard norm, and the weighted norm. Our results show that the quasi-optimal norm leads to more accurate results on three benchmark problems in two spatial dimensions. We address the problems associated to the resolution of the optimal test functions with respect to the quasi-optimal norm by studying their convergence numerically. In order to facilitate understanding of the method, we also include a detailed explanation of the methodology from the algorithmic point of view. © 2013 Elsevier Ltd. All rights reserved.

  18. Problems associated with the application of short-term tests for mutagenicity in mass-screening programs.

    Science.gov (United States)

    de Serres, F J

    1979-01-01

    The application of short-term tests for toxicological evaluation of environmental chemicals is certainly a reality in the near future as a result of the Toxic Substances Control Act, as well as other regulations under development [de Serres, 1977]. Many of the problems associated with this testing in the area of genetic toxicology are under study at the National Institute of Environmental Health Sciences in our National Toxicology Program and at the Environmental Protection Agency in their Gene-Tox Program. The other problems that I have discussed in connection with standardization of protocols, protocol review and modification, and training of personnel are not being pursued aggressively. Perhaps with their definition and acceptance as meaningful problems, mechanisms will be established for their resolution. It is in these latter areas that I hope that this society can provide the forceful leadership that will result in their resolution in the near future.

  19. The Influence of Maternal Acculturation, Neighborhood Disadvantage, and Parenting on Chinese American Adolescents' Conduct Problems: Testing the Segmented Assimilation Hypothesis

    Science.gov (United States)

    Liu, Lisa L.; Lau, Anna S.; Chen, Angela Chia-Chen; Dinh, Khanh T.; Kim, Su Yeong

    2009-01-01

    Associations among neighborhood disadvantage, maternal acculturation, parenting and conduct problems were investigated in a sample of 444 Chinese American adolescents. Adolescents (54% female, 46% male) ranged from 12 to 15 years of age (mean age = 13.0 years). Multilevel modeling was employed to test the hypothesis that the association between…

  20. Dynamic Testing of Gifted and Average-Ability Children's Analogy Problem Solving: Does Executive Functioning Play a Role?

    Science.gov (United States)

    Vogelaar, Bart; Bakker, Merel; Hoogeveen, Lianne; Resing, Wilma C. M.

    2017-01-01

    In this study, dynamic testing principles were applied to examine progression of analogy problem solving, the roles that cognitive flexibility and metacognition play in children's progression as well as training benefits, and instructional needs of 7- to 8-year-old gifted and average-ability children. Utilizing a pretest training posttest control…

  1. A Test of the Circumvention-of-Limits Hypothesis in Scientific Problem Solving: The Case of Geological Bedrock Mapping

    Science.gov (United States)

    Hambrick, David Z.; Libarkin, Julie C.; Petcovic, Heather L.; Baker, Kathleen M.; Elkins, Joe; Callahan, Caitlin N.; Turner, Sheldon P.; Rench, Tara A.; LaDue, Nicole D.

    2012-01-01

    Sources of individual differences in scientific problem solving were investigated. Participants representing a wide range of experience in geology completed tests of visuospatial ability and geological knowledge, and performed a geological bedrock mapping task, in which they attempted to infer the geological structure of an area in the Tobacco…

  2. Patch testing with markers of fragrance contact allergy. Do clinical tests correspond to patients' self-reported problems?

    DEFF Research Database (Denmark)

    Johansen, J D; Andersen, T F; Veien, Niels

    1997-01-01

    in a questionnaire prior to patch testing with the European standard series. The questionnaire contained questions about skin symptoms from the use of scented and unscented products as well as skin reactions from contact with spices, flowers and citrus fruits that could indicate fragrance sensitivity. A highly...

  3. Patch testing with markers of fragrance contact allergy. Do clinical tests correspond to patients' self-reported problems?

    DEFF Research Database (Denmark)

    Johansen, J D; Andersen, T F; Veien, Niels

    1997-01-01

    significant association was found between reporting a history of visible skin symptoms from using scented products and a positive patch test to the fragrance mix, whereas no such relationship could be established to the Peru balsam in univariate or multivariate analysis. Our results suggest that the role...

  4. 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...... in Denmark who had received a Mitroflow aortic bioprosthesis since 2000. METHODS: Patients alive in Denmark with a Mitroflow bioprosthesis implanted since January 2000 were invited to participate in a nationwide cross-sectional study with a predefined definition of SVD. Of 1552 patients, 861 patients had...

  5. Discrete Structure-Point Testing: Problems and Alternatives. TESL Reporter, Vol. 9, No. 4.

    Science.gov (United States)

    Aitken, Kenneth G.

    This paper presents some reasons for reconsidering the use of discrete structure-point tests of language proficiency, and suggests an alternative basis for designing proficiency tests. Discrete point tests are one of the primary tools of the audio-lingual method of teaching a foreign language and are based on certain assumptions, including the…

  6. Development of mechanical heart valves - an inspiring tale

    Directory of Open Access Journals (Sweden)

    P Rajashekar

    2015-01-01

    Full Text Available The historical evolution of the prosthetic heart valves from the first attempts with the Hufnagel′s valve in the treatment of the aortic insufficiency to the Starr-Edwards′ ball valve and later the tilting disc valves (Bjork-Shiley etc., and finally the bileaflet valves (St. Jude are discussed. The Indian contribution with Chitra valve is also described.

  7. A retrospective analysis of mitral valve pathology in the setting of bicuspid aortic valves

    Science.gov (United States)

    van Rensburg, Annari; Doubell, Anton

    2017-01-01

    The therapeutic implications of bicuspid aortic valve associations have come under scrutiny in the transcatheter aortic valve implantation era. We evaluate the spectrum of mitral valve disease in patients with bicuspid aortic valves to determine the need for closer echocardiographic scrutiny/follow-up of the mitral valve. A retrospective analysis of echocardiograms done at a referral hospital over five years was conducted in patients with bicuspid aortic valves with special attention to congenital abnormalities of the mitral valve. One hundred and forty patients with a bicuspid aortic valve were included. A congenital mitral valve abnormality was present in eight (5.7%, P = 0.01) with a parachute mitral valve in four (2.8%), an accessory mitral valve leaflet in one (0.7%), mitral valve prolapse in one, a cleft in one and the novel finding of a trileaflet mitral valve in one. Minor abnormalities included an elongated anterior mitral valve leaflet (P abnormal papillary muscles (P = 0.002) and an additional chord or tendon in the left ventricle cavity (P = 0.007). Mitral valve abnormalities occur more commonly in patients with bicuspid aortic valves than matched healthy individuals. The study confirms that abnormalities in these patients extend beyond the aorta. These abnormalities did not have a significant functional effect. PMID:28515127

  8. 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

    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...

  9. A retrospective analysis of mitral valve pathology in the setting of bicuspid aortic valves.

    Science.gov (United States)

    van Rensburg, Annari; Herbst, Philip; Doubell, Anton

    2017-06-01

    The therapeutic implications of bicuspid aortic valve associations have come under scrutiny in the transcatheter aortic valve implantation era. We evaluate the spectrum of mitral valve disease in patients with bicuspid aortic valves to determine the need for closer echocardiographic scrutiny/follow-up of the mitral valve. A retrospective analysis of echocardiograms done at a referral hospital over five years was conducted in patients with bicuspid aortic valves with special attention to congenital abnormalities of the mitral valve. One hundred and forty patients with a bicuspid aortic valve were included. A congenital mitral valve abnormality was present in eight (5.7%, P = 0.01) with a parachute mitral valve in four (2.8%), an accessory mitral valve leaflet in one (0.7%), mitral valve prolapse in one, a cleft in one and the novel finding of a trileaflet mitral valve in one. Minor abnormalities included an elongated anterior mitral valve leaflet (P mitral regurgitation (P Mitral valve abnormalities occur more commonly in patients with bicuspid aortic valves than matched healthy individuals. The study confirms that abnormalities in these patients extend beyond the aorta. These abnormalities did not have a significant functional effect. © 2017 The authors.

  10. Should a Regurgitant Mitral Valve Be Replaced Simultaneously with a Stenotic Aortic Valve?

    OpenAIRE

    Christenson, Jan T.; Jordan, Bernard; Bloch, Antoine; Schmuziger, Martin

    2000-01-01

    Mitral valve regurgitation frequently accompanies aortic valve stenosis. It has been suggested that mitral regurgitation improves after aortic valve replacement alone and that the mitral valve need not be replaced simultaneously. Furthermore, mitral regurgitation associated with coronary artery disease, particularly in patients with poor left ventricular function, shows immediate improvement after coronary artery bypass grafting.

  11. [Is it necessary to test children having summer respiratory problems with cereal pollens?].

    Science.gov (United States)

    Lelong, M; Thibaudon, M; Thelliez, P H

    1989-12-01

    We tested 100 children with clinical signs that occurred in spring or summer. Prick tests were made with extracts of wild grass pollens (Dactylis, Phleum, Lolium) and with separate cereal pollens (Wheat, oats, Sweet-corn Barley and Rye). In 20 children whose test was negative for wild grass pollen, we saw no sensitization to cereals. In 80 children with grass pollenosis, Barley and Rye are the cereals that gave the most positive prick tests, whilst sweet corn is the cereal with most negative tests.

  12. Persistent radiographic cone cuts: A simple test to avoid the frustrating problem

    OpenAIRE

    Santosh Gowdru Shivanandappa; Lata Shankarappa Mushannavar; Girish Katti

    2014-01-01

    In routine dental radiography, one may encounter numerous radiographic errors, one of which may be partial images or cone cuts. These cones cut errors although may appear as simple problems, but often persistent cone cuts may be frustrating to the dental practitioner. In this study, our main aim was to find and solve the origin of the problem. This study was conducted with two different intraoral X-ray machines with 12 inch length position indicating devices (PIDs) with four No. 2 intraoral f...

  13. The Planar Sandwich and Other 1D Planar Heat Flow Test Problems in ExactPack

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, Jr., Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-24

    This report documents the implementation of several related 1D heat flow problems in the verification package ExactPack [1]. In particular, the planar sandwich class defined in Ref. [2], as well as the classes PlanarSandwichHot, PlanarSandwichHalf, and other generalizations of the planar sandwich problem, are defined and documented here. A rather general treatment of 1D heat flow is presented, whose main results have been implemented in the class Rod1D. All planar sandwich classes are derived from the parent class Rod1D.

  14. 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.

  15. 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.

  16. Control of the valve system of multicyclic bed testers

    Energy Technology Data Exchange (ETDEWEB)

    Lopatkin, O.P.; Varlamov, P.S.

    1980-01-01

    It has been established that in testing beds with the help of multicyclic testers in twisted wells, the height of lifting the pipes for closure of the valve should be determined with regard for the resistance forces during movement of the drilling pipe string. A plan is presented for the pipe shaft with lowered drilling string after installation of the packer. The technique developed in the North Caucasus Scientific Research and Planning Institute of the Oil Industry will make it possible to determine for deep twisted wells the height of lifting of the string drilling pipes needed to close the safety valve of the multicyclic bed tester.

  17. Autologous valve replacement-CD133+ stem cell-plus-fibrin composite-based sprayed cell seeding for intraoperative heart valve tissue engineering.

    Science.gov (United States)

    Kaminski, Alexander; Klopsch, Christian; Mark, Peter; Yerebakan, Can; Donndorf, Peter; Gäbel, Ralf; Eisert, Friederike; Hasken, Stefan; Kreitz, Sebastian; Glass, Aenne; Jockenhövel, Stefan; Ma, Nan; Kundt, Guenther; Liebold, Andreas; Steinhoff, Gustav

    2011-03-01

    The development of biological valve prostheses with lifetime native-like performance and optimal host engraftment is an ultimate goal of heart valve tissue engineering. We describe a new concept for autologous graft coating based on a CD133(+)-stem-cells-plus-fibrin (SC+F) complex processed from bone marrow and peripheral blood of a single patient. CD133(+)-SC (1 × 10(6) cells/mL) from human bone marrow and autologous fibrin (20 mg/mL) were administered simultaneously via spray administration using the novel Vivostat Co-Delivery System. During static cultivation, SC+F performance was monitored for 20 days after delivery and compared with controls. For dynamic testing SC+F-composite was sprayed on a decellularized porcine pulmonary valve and transferred to a bioreactor under pulsatile flow conditions for 7 days. Static cultivation of SC+F-composite induced significant improvements in stem cell proliferation as compared with controls. For dynamic testing, microscopic analyses on a smooth engineered heart valve surface detected homogenous distribution of stem cells. Ultrasonic analysis revealed native-like valve performance. Applied CD133(+) stem cells differentiated into endothelial-like cells positive for CD31 and vascular endothelial growth factor receptor 2 and engrafted the valve. However, occasional delamination was observed. SC+F serves as an excellent autologous matrix for intraoperative tissue engineering of valve prostheses promising optimal in vivo integration. However, stability remains an issue.

  18. 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 MitraClip system resembles the Alfieristitch where a clip is used to connect the tip of the mitral valve leaflets....

  19. 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....

  20. Intertester reliability of clinical shoulder instability and laxity tests in subjects with and without self-reported shoulder problems.

    Science.gov (United States)

    Eshoj, Henrik; Ingwersen, Kim Gordon; Larsen, Camilla Marie; Kjaer, Birgitte Hougs; Juul-Kristensen, Birgit

    2018-03-03

    First, to investigate the intertester reliability of clinical shoulder instability and laxity tests, and second, to describe the mutual dependency of each test evaluated by each tester for identifying self-reported shoulder instability and laxity. A standardised protocol for conducting reliability studies was used to test the intertester reliability of the six clinical shoulder instability and laxity tests: apprehension, relocation, surprise, load-and-shift, sulcus sign and Gagey. Cohen's kappa (κ) with 95% CIs besides prevalence-adjusted and bias-adjusted kappa (PABAK), accounting for insufficient prevalence and bias, were computed to establish the intertester reliability and mutual dependency. Forty individuals (13 with self-reported shoulder instability and laxity-related shoulder problems and 27 normal shoulder individuals) aged 18-60 were included. Fair (relocation), moderate (load-and-shift, sulcus sign) and substantial (apprehension, surprise, Gagey) intertester reliability were observed across tests (κ 0.39-0.73; 95% CI 0.00 to 1.00). PABAK improved reliability across tests, resulting in substantial to almost perfect intertester reliability for the apprehension, surprise, load-and-shift and Gagey tests (κ 0.65-0.90). Mutual dependencies between each test and self-reported shoulder problem showed apprehension, relocation and surprise to be the most often used tests to characterise self-reported shoulder instability and laxity conditions. Four tests (apprehension, surprise, load-and-shift and Gagey) out of six were considered intertester reliable for clinical use, while relocation and sulcus sign tests need further standardisation before acceptable evidence. Furthermore, the validity of the tests for shoulder instability and laxity needs to be studied. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rho, Hyung Joon; Lee, Jee Keun [Chonbuk National Univ., Jeonju (Korea, Republic of); Choi, Hee Joo [Firstec Co., Ltd., Changwon (Korea, Republic of)

    2008-01-15

    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.

  2. Dispositional and Environmental Predictors of the Development of Internalizing Problems in Childhood: Testing a Multilevel Model.

    Science.gov (United States)

    Hastings, Paul D; Helm, Jonathan; Mills, Rosemary S L; Serbin, Lisa A; Stack, Dale M; Schwartzman, Alex E

    2015-07-01

    This investigation evaluated a multilevel model of dispositional and environmental factors contributing to the development of internalizing problems from preschool-age to school-age. In a sample of 375 families (185 daughters, 190 sons) drawn from three independent samples, preschoolers' behavioral inhibition, cortisol and gender were examined as moderators of the links between mothers' negative parenting behavior, negative emotional characteristics, and socioeconomic status when children were 3.95 years, and their internalizing problems when they were 8.34 years. Children's dispositional characteristics moderated all associations between these environmental factors and mother-reported internalizing problems in patterns that were consistent with either diathesis-stress or differential-susceptibility models of individual-environment interaction, and with gender models of developmental psychopathology. Greater inhibition and lower socioeconomic status were directly predictive of more teacher reported internalizing problems. These findings highlight the importance of using multilevel models within a bioecological framework to understand the complex pathways through which internalizing difficulties develop.

  3. An Instructors Guide to Water Pollution. Test Edition. AAAS Study Guides on Contemporary Problems, No. 5.

    Science.gov (United States)

    Kidd, David E.

    This is one of several study guides on contemporary problems produced by the American Association for the Advancement of Science with support of the National Science Foundation. This study guide on water pollution includes the following units: (1) Overview of World Pollution; (2) History, Definition, Criteria; (3) Ecosystem Theory; (4) Biological…

  4. The Ethnology of Traditional and Complex Societies. Test Edition. AAAS Study Guides on Contemporary Problems.

    Science.gov (United States)

    Simic, Andrei

    This is one of several study guides on contemporary problems produced by the American Association for the Advancement of Science with support of the National Science Foundation. This guide focuses on the ethnology of traditional and complex societies. Part I, Simple and Complex Societies, includes three sections: (1) Introduction: Anthropologists…

  5. Problems with Contingency Theory: Testing Assumptions Hidden within the Language of Contingency "Theory".

    Science.gov (United States)

    Schoonhoven, Clausia Bird

    1981-01-01

    Discusses problems in contingency theory, which relates organizational structure to the tasks performed and the information needed. Analysis of data from 17 hospitals suggests that traditional contingency theory underrepresents the complexity of relations among technological uncertainty, structure, and organizational effectiveness. (Author/RW)

  6. A Test of Problem Behavior and Self-Medication Theories in Incarcerated Adolescent Males

    Science.gov (United States)

    Esposito-Smythers, Christianne; Penn, Joseph V.; Stein, L. A. R.; Lacher-Katz, Molly; Spirito, Anthony

    2008-01-01

    The purpose of this study is to examine the problem behavior and self-medication models of alcohol abuse in incarcerated male adolescents. Male adolescents (N = 56) incarcerated in a juvenile correction facility were administered a battery of psychological measures. Approximately 84% of adolescents with clinically significant alcohol-related…

  7. Rhetorical Dissent as an Adaptive Response to Classroom Problems: A Test of Protection Motivation Theory

    Science.gov (United States)

    Bolkan, San; Goodboy, Alan K.

    2016-01-01

    Protection motivation theory (PMT) explains people's adaptive behavior in response to personal threats. In this study, PMT was used to predict rhetorical dissent episodes related to 210 student reports of perceived classroom problems. In line with theoretical predictions, a moderated moderation analysis revealed that students were likely to voice…

  8. The dynamic characteristics of a valve-less micropump

    Science.gov (United States)

    Jiang, Dan; Li, Song-Jing

    2012-07-01

    The aim of this paper is to investigate the dynamic characteristics of a valve-less micropump. A dynamic mathematical model of the micropump based on a hydraulic analogue system and a simulation method using AMESim software are developed. By using the finite-element analysis method, the static analysis of the diaphragm is carried out to obtain the maximum deflection and volumetric displacement. Dynamic characteristics of the valve-less micropump under different excitation voltages and frequencies are simulated and tested. Because of the discrepancy between simulation results and experimental data at frequencies other than the natural frequency, the revised model for the diaphragm maximum volumetric displacement is presented. Comparison between the simulation results based on the revised model and experimental data shows that the dynamic mathematical model based on the hydraulic analogue system is capable of predicting dynamic characteristics of the valve-less micropump at any excitation voltage and frequency.

  9. The Use of the Ames Test as a Tool for Addressing Problem-Based Learning in the Microbiology Lab

    Directory of Open Access Journals (Sweden)

    Eliana Rodríguez

    2012-08-01

    Full Text Available Our environment is full of potential carcinogens such as UV light, industrial pollutants, pesticides, and food additives, among others. It is estimated that 90% of all carcinogens are also mutagens. The Ames test is one of the most common tests for mutagens. In this problem-based learning activity, undergraduate biology students used the Ames test to screen a substance they provided, to see if it could be considered a mutagen. The idea of surveying substances used in everyday life appealed to our students, and helped engage them in this activity.

  10. Problems with rapid agglutination methods for identification of Staphylococcus aureus when Staphylococcus saprophyticus is being tested.

    OpenAIRE

    Gregson, D B; Low, D E; Skulnick, M; Simor, A E

    1988-01-01

    Six rapid agglutination tests for identification of Staphylococcus aureus were evaluated by using 62 strains of S. aureus, 63 strains of S. saprophyticus, and 67 strains of other coagulase-negative staphylococci. S. saprophyticus was responsible for 19 of 26 false-positive results and 20 uninterpretable reactions. Thus, urinary staphylococcal isolates that are positive by rapid agglutination tests may require other confirmatory tests for the identification of possible S. saprophyticus.

  11. PROBLEM OF OPTIMIZATION OF COMPUTER TEST CONTROL OF EDUCATIONAL ACHIEVEMENTS OF STUDENTS IN UKRAINIAN LANGUAGE (FOR PROFESSIONAL PURPOSES

    Directory of Open Access Journals (Sweden)

    Svitlana V. Shyyka

    2017-09-01

    Full Text Available The article is devoted to the research of the problem of optimization of computer test control of academic achievements of students in the discipline “Ukrainian language (for professional purposes”. The content of the concepts “test”, “pedagogical test”, “test task” is explained, the classification of possible formats of test tasks is given, the principles of selecting the contents of tasks in the test form are determined, the positive and negative aspects of the computer test method of checking knowledge, skills and abilities are revealed. List of programs for testing knowledge and one of them ‒ MyTest, a table of didactic and methodical materials for preparation and conducting of test control of knowledge on the basis of the program MyTestX is presented. It is emphasized that the effectiveness of computer testing depends on the level of teacher training, the experience of his teaching activities and the practice of using test technologies, the ability and the need for creativity and self-improvement.

  12. 49 CFR 195.420 - Valve maintenance.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valve maintenance. 195.420 Section 195.420 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Operation and Maintenance § 195.420 Valve maintenance. (a) Each operator shall maintain each valve...

  13. Double orifice mitral valve; a coincidental finding

    NARCIS (Netherlands)

    Westendorp, Iris C. D.; de Bruin-Bon, H. A. C. M.; Hrudova, Jana

    2006-01-01

    A double orifice mitral valve (DOMV) represents a rare congenital malformation characterised by two valve orifices with two separate subvalvular apparatus. This case demonstrates the necessity of careful imaging of the mitral valve apparatus, not only in patients with atrioventricular septal

  14. Pregnancy in women with prosthetic heart valves

    NARCIS (Netherlands)

    Pieper, P. G.; Balci, A.; Van Dijk, A. P.

    2008-01-01

    Pregnancy in women with mechanical valve prostheses has a high maternal complication rate including valve thrombosis mid death. Coumarin derivatives are relatively safe for the mother with a lower incidence of valve thrombosis than unfractionated and low-molecular-weight heparin, but carry the risk

  15. Pregnancy in women with prosthetic heart valves.

    NARCIS (Netherlands)

    Pieper, P.G.; Balci, A.; Dijk, A.P.J. van

    2008-01-01

    Pregnancy in women with mechanical valve prostheses has a high maternal complication rate including valve thrombosis and death. Coumarin derivatives are relatively safe for the mother with a lower incidence of valve thrombosis than un-fractionated and low-molecular-weight heparin, but carry the risk

  16. Transcatheter mitral valve implantation via transapical approach

    DEFF Research Database (Denmark)

    Sondergaard, Lars; Brooks, Matthew; Ihlemann, Nikolaj

    2015-01-01

    OBJECTIVES: As many as 50% of patients with severe symptomatic mitral valve regurgitation are denied surgical valve replacement or repair due to high operative risk. We describe an early series of cases of transcatheter implantation with a CardiAQ™ mitral valve via a transapical approach. METHODS...

  17. 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.

  18. 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...

  19. Native valve endocarditis due to Candida parapsilosis in an adult ...

    African Journals Online (AJOL)

    We describe a case of Candida parapsilosis endocarditis in an HIV-positive patient with pre-existing mitral valve disease and renal failure on haemodialysis. ... Blood cultures were positive for C. parapsilosis. β-D-glucan assay levels were elevated. .... presence of negative blood cultures suggests that this test is not reliable.

  20. Design of a Maglev Vibration Test Platform for the Research of Maglev Vehicle-girder Coupled Vibration Problem

    Directory of Open Access Journals (Sweden)

    Zhou Danfeng

    2017-01-01

    Full Text Available The maglev vehicle-girder coupled vibration problem has been encountered in many maglev test or commercial lines, which significantly degrade the performance of the maglev train. In previous research on the principle of the coupled vibration problem, it has been discovered that the fundamental model of the maglev girder can be simplified as a series of mass-spring resonators of different but related resonance frequencies, and that the stability of the vehicle-girder coupled system can be investigated by separately examining the stability of each mass-spring resonator – electromagnet coupled system. Based on this conclusion, a maglev test platform, which includes a single electromagnetic suspension control system, is built for experimental study of the coupled vibration problem. The guideway of the test platform is supported by a number of springs so as to change its flexibility. The mass of the guideway can also be changed by adjusting extra weights attached to it. By changing the flexibility and mass of the guideway, the rules of the maglev vehicle-girder coupled vibration problem are to be examined through experiments, and related theory on the vehicle-girder self-excited vibration proposed in previous research is also testified.

  1. The two-stroke poppet valve engine. Part 1: Intake and exhaust ports flow experimental assessments

    Science.gov (United States)

    Kamili Zahidi, M.; Razali Hanipah, M.; Ramasamy, D.; Noor, M. M.; Kadirgama, K.; Rahman, M. M.

    2017-10-01

    A two-stroke poppet valve engine is developed to overcome the common problems in conventional two-stroke engine designs. However, replacing piston control port with poppet valve will resulted different flow behaviour. This paper is looking at experimental assessment on a two-stroke poppet valve engine configuration to investigate the port flow performance. The aims are to evaluate the intake and exhaust coefficient of discharge and assess the twostroke capability of the cylinder head. The results has shown comparable coefficient of discharge values as production engine for the intake while the exhaust has higher values which is favourable for the two-stroke cycle operation.

  2. 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.

  3. [The Starr-Edwards heart valve: one of the oldest mechanical heart valves still functioning today].

    Science.gov (United States)

    Schoenaker, Michiel H; van Wetten, Herbert B; Morshuis, Wim J

    2015-01-01

    In the 1960s, the Starr-Edwards valve was the first artificial heart valve to be successfully implanted in humans. This valve has now been in use for decades with outstanding results: patients whose life expectancy had previously been short acquired a good prognosis with this development. Nowadays the Starr-Edwards valve is not used anymore, but patients are being described today in whom these valves are still functioning well after more than 40 years.

  4. Effect of Flow Characteristics in the Downstream of Butterfly Valve on the Flow Rate Measurement using Venturi Tube

    Science.gov (United States)

    Yoon, Seok Ho; Lee, Jungho; Yu, Cheong Hwan; Park, San-Jin; Chung, Chang-Hwan

    2010-06-01

    For testing large-capacity pump, the accurate flow rate measurement is needed in the test loop. As a measuring method of flow rate, venturi tube is recommended due to its low pressure loss. However, upstream disturbance of loop component such as valve has an effect upon the accuracy of flow rate measurement. For controlling flow rate in case of high flow rate and large-scale piping system, butterfly-type valve is generally used due to its compactness. However, butterfly valve disturbs downstream flow by generating turbulence, cavities, or abrupt pressure change. In this study, the effect of downstream disturbance of butterfly valve on the flow rate measurement using venturi tube is investigated. Test loop consists of circulation pump, reservoir, butterfly valve, venturi tube, and reference flow meter. The test is conducted with regard to a different valve opening angle of butterfly valve. PIV system is used to visualize and analyze flow in the downstream region of butterfly valve. According to valve opening angle, the flow characteristics and the accuracy of flow rate measurement are investigated.

  5. Direct and Inverse Problems of Item Pool Design for Computerized Adaptive Testing

    Science.gov (United States)

    Belov, Dmitry I.; Armstrong, Ronald D.

    2009-01-01

    The recent literature on computerized adaptive testing (CAT) has developed methods for creating CAT item pools from a large master pool. Each CAT pool is designed as a set of nonoverlapping forms reflecting the skill levels of an assumed population of test takers. This article presents a Monte Carlo method to obtain these CAT pools and discusses…

  6. A Note on Some Problems in the Testing of Personality Characteristics in Children with Visual Impairment

    Science.gov (United States)

    Tobin, Michael; Hill, Eileen

    2010-01-01

    An examination is made of the value of using published personality tests with young blind and partially sighted children. Based on data gathered during a longitudinal investigation into the educational and psychological development of a group of 120 visually impaired learners, the authors conclude that their own selection of a test instrument…

  7. The problem of false-positive human papillomavirus DNA tests in cervical screening

    DEFF Research Database (Denmark)

    Rebolj, Matejka; Pribac, Igor; Frederiksen, Maria Eiholm

    2013-01-01

    Human Papillomavirus (HPV) testing has been extensively studied in randomized controlled trials of primary cervical screening. Based on encouraging results concerning its high detection rates and a high negative predictive value for high-grade cervical intraepithelial neoplasia (CIN), HPV testing...

  8. Problem-Solving Test: Analysis of DNA Damage Recognizing Proteins in Yeast and Human Cells

    Science.gov (United States)

    Szeberenyi, Jozsef

    2013-01-01

    The experiment described in this test was aimed at identifying DNA repair proteins in human and yeast cells. Terms to be familiar with before you start to solve the test: DNA repair, germline mutation, somatic mutation, inherited disease, cancer, restriction endonuclease, radioactive labeling, [alpha-[superscript 32]P]ATP, [gamma-[superscript…

  9. The Major Field Test in Business: A Solution to the Problem of Assurance of Learning Assessment?

    Science.gov (United States)

    Green, Jeffrey J.; Stone, Courtenay Clifford; Zegeye, Abera

    2014-01-01

    Colleges and universities are being asked by numerous sources to provide assurance of learning assessments of their students and programs. Colleges of business have responded by using a plethora of assessment tools, including the Major Field Test in Business. In this article, the authors show that the use of the Major Field Test in Business for…

  10. Memorizing: a test of untrained mildly mentally retarded children's problem-solving.

    Science.gov (United States)

    Belmont, J M; Ferretti, R P; Mitchell, D W

    1982-09-01

    Forty untrained mildly mentally retarded and 32 untrained nonretarded junior high school students were given eight trails of practice on a self-paced memory problem with lists of letters or words. For each trail a new list was presented, requiring ordered recall of terminal list items followed by ordered recall of initial items. Subgroups of solvers and nonsolvers were identified at each IQ level by a criterion of strict recall accuracy. Direct measures of mnemonic activity showed that over trails, solvers at both IQ levels increasingly fit a theoretically ideal memorization method. At neither IQ level did nonsolvers show similar inventions. On early trials, for both IQ levels, fit to the ideal method was uncorrelated with recall accuracy. On late trials fit and recall were highly correlated at each IQ level and across levels. The results support a problem-solving theory of individual differences in retarded and nonretarded children's memory performances.

  11. On the open/close performance of prosthetic heart valves at high frequencies

    Science.gov (United States)

    Beltran, A.; Zenit, R.

    2013-11-01

    We report experimental observations of the performance of mechanical and biological prosthetic heart valves. The valves are mounted in a test circular channel conected to a flow system that emulates accelerated human-like conditions. The flow is generated by a high frequencie pulsative pump (in the range of 7 to 18 Hz). The objective of the investigation is to find the treshold conditions for which the open/close performance fails. Preliminary results show that for the mechanical valve the failure starts at 436 pulses/min, while for the biological valve, it starts a failing performance is observed for frequencies higher that 462 pulses/min. Even though these values are far from the heart rate in the human body, we use these measurements to further understand the structure-fluid interaction mechanics of the flow through heart valves.

  12. Testing the water - problem-based learning and the cultural dimension.

    Science.gov (United States)

    Darvill, Angela

    2003-06-01

    This study reports the findings of a small case study using problem-based learning (PBL) as a teaching and learning strategy in a cultural awareness module, which forms part of a pre-registration diploma in nursing course. The study was carried out using a qualitative research methodology. It aimed to describe and explore 20 diplomat student nurses and their lecturers' experience of undertaking PBL. The categories that emerged from the analysis were: knowledge development and PBL process. A selection of these categories and their sub-categories are described and discussed in relation to the literature on problem-based learning. The study concluded that undergoing PBL as a teaching and learning strategy had positive outcomes for the students. Prior knowledge was utilised in knowledge development in relation to the problem and was seen as beneficial. Students reported that they felt more confident and used the knowledge gained to care for patients' cultural needs in practice. Students also identified lack of knowledge amongst staff in the clinical area in relation to cultural awareness. There were however some challenges in the transition to a PBL strategy from the perspective of the students and lecturers. Issues that were found to be difficult include the change to a different teaching and learning strategy, the implications of self-direction for the student and the role of the facilitator as a non-directive guide. The study recommends that the findings may be of use for other nurse educators implementing PBL as a teaching and learning strategy.

  13. Living nano-micro fibrous woven fabric/hydrogel composite scaffolds for heart valve engineering.

    Science.gov (United States)

    Wu, Shaohua; Duan, Bin; Qin, Xiaohong; Butcher, Jonathan T

    2017-03-15

    Regeneration and repair of injured or diseased heart valves remains a clinical challenge. Tissue engineering provides a promising treatment approach to facilitate living heart valve repair and regeneration. Three-dimensional (3D) biomimetic scaffolds that possess heterogeneous and anisotropic features that approximate those of native heart valve tissue are beneficial to the successful in vitro development of tissue engineered heart valves (TEHV). Here we report the development and characterization of a novel composite scaffold consisting of nano- and micro-scale fibrous woven fabrics and 3D hydrogels by using textile techniques combined with bioactive hydrogel formation. Embedded nano-micro fibrous scaffolds within hydrogel enhanced mechanical strength and physical structural anisotropy of the composite scaffold (similar to native aortic valve leaflets) and also reduced its compaction. We determined that the composite scaffolds supported the growth of human aortic valve interstitial cells (HAVIC), balanced the remodeling of heart valve ECM against shrinkage, and maintained better physiological fibroblastic phenotype in both normal and diseased HAVIC over single materials. These fabricated composite scaffolds enable the engineering of a living heart valve graft with improved anisotropic structure and tissue biomechanics important for maintaining valve cell phenotypes. Heart valve-related disease is an important clinical problem, with over 300,000 surgical repairs performed annually. Tissue engineering offers a promising strategy for heart valve repair and regeneration. In this study, we developed and tissue engineered living nano-micro fibrous woven fabric/hydrogel composite scaffolds by using textile technique combined with bioactive hydrogel formation. The novelty of our technique is that the composite scaffolds can mimic physical structure anisotropy and the mechanical strength of natural aortic valve leaflet. Moreover, the composite scaffolds prevented the

  14. Commonwealth Edison Company pressure locking test report

    Energy Technology Data Exchange (ETDEWEB)

    Bunte, B.D.; Kelly, J.F.

    1996-12-01

    Pressure Locking is a phenomena which can cause the unseating thrust for a gate valve to increase dramatically from its typical static unseating thrust. This can result in the valve actuator having insufficient capability to open the valve. In addition, this can result in valve damage in cases where the actuator capability exceeds the valve structural limits. For these reasons, a proper understanding of the conditions which may cause pressure locking and thermal binding, as well as a methodology for predicting the unseating thrust for a pressure locked or thermally bound valve, are necessary. This report discusses the primary mechanisms which cause pressure locking. These include sudden depressurization of piping adjacent to the valve and pressurization of fluid trapped in the valve bonnet due to heat transfer. This report provides a methodology for calculating the unseating thrust for a valve which is pressure locked. This report provides test data which demonstrates the accuracy of the calculation methodology.

  15. The Structure of Wheel Check Valve Influence on Air Block Phenomenon of Piezoelectric Micro-Pump

    Directory of Open Access Journals (Sweden)

    Song Chen

    2015-11-01

    Full Text Available To improve the stability and reliability of the piezoelectric micro-pump, the cause of air block phenomenon is analyzed on the structure of wheel check valve. During the movement of the bubble in the micro-channel, pressure drop occurs, the main factor which influences the bubble going through is opening height of the wheel check valve. Five groups of wheel check valves with different structures are used to test the wheel check valve opening height and air block probability. The experiment results show that reducing the wheel check valve thickness or diameter ratio can both increase the wheel check valve opening height, and decrease the air block probability. Through experiment, the optimum combination of the wheel check valve structure is obtained within the samples: as the thickness is 0.02 mm, the diameter ratio is 1.2, the wheel check valve opening height gets 252 µm, and within the given bubble volume, the air block probability is less than 2%.

  16. Qualitative haemodynamic validation of a percutaneous temporary aortic valve: a proof of concept study.

    Science.gov (United States)

    Ho, P C

    2011-02-01

    The concept of temporary aortic valves has been suggested in the clinical settings of acute aortic regurgitation and transcatheter aortic valve replacement procedure (TAVR). In TAVR, suggestions have been made to pre-treat or remove the diseased aortic valve prior to implantation of the replacement valve. A successful temporary aortic valve must demonstrate the ability to prevent life-threatening haemodynamics of massive aortic regurgitation. A novel temporary aortic valve (TAV) design, comprised of inflatable balloon elements as a check-valve, can readily be deployed and retrieved via a catheter-system. A simple flow model is set up to test the TAV's performance in severe aortic regurgitation. With induced aortic regurgitation, placement of the TAV is found to increase the distal aortic diastolic pressure, to reduce the widened pulse pressure, to protect proximal aorta-left ventricle from diastolic pressure elevation and to reduce the aortic regurgitant volume. In conclusion, continued development of the TAV system can lead to a successful temporary aortic valve to be used in various appropriate clinical settings.

  17. Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering.

    Science.gov (United States)

    Jahnavi, S; Saravanan, U; Arthi, N; Bhuvaneshwar, G S; Kumary, T V; Rajan, S; Verma, R S

    2017-04-01

    Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44+, αSMA+, Vimentin+ and CD105- human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Second order analysis of two-stage rank tests for the one-sample problem

    NARCIS (Netherlands)

    Albers, Willem/Wim

    1991-01-01

    In this paper we present a rank analogue to Stein's two-stage procedure. We analyze its behavior to second order using existing asymptotic expansions for fixed sample size rank tests and recent results on combinations of independent rank statistics.

  19. Testing Vegetation Flammability: The Problem of Extremely Low Ignition Frequency and Overall Flammability Score

    Directory of Open Access Journals (Sweden)

    Zorica Kauf

    2014-01-01

    Full Text Available In the recent decades changes in fire regimes led to higher vulnerability of fire prone ecosystems, with vegetation being the only component influencing fire regime which can be managed in order to reduce probability of extreme fire events. For these management practices to be effective reliable information on the vegetation flammability is being crucial. Epiradiator based testing methods are one of the methods commonly used to investigate vegetation flammability and decrease in ignition frequency is always interpreted as a decrease in flammability. Furthermore, gathered information is often combined into a single flammability score. Here we present results of leaf litter testing which, together with previously conducted research on similar materials, show that material with very low ignition frequency under certain testing conditions can be extremely flammable if testing conditions are slightly changed. Additionally, our results indicate that combining measured information into one single flammability score, even though sometimes useful, is not always meaningful and should be performed with caution.

  20. Imaging of Cardiac Valves by Computed Tomography

    OpenAIRE

    Gudrun Feuchtner

    2013-01-01

    This paper describes “how to” examine cardiac valves with computed tomography, the normal, diseased valves, and prosthetic valves. A review of current scientific literature is provided. Firstly, technical basics, “how to” perform and optimize a multislice CT scan and “how to” interpret valves on CT images are outlined. Then, diagnostic imaging of the entire spectrum of specific valvular disease by CT, including prosthetic heart valves, is highlighted. The last part gives a guide “how to” use ...