These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Engine valve train system  

Microsoft Academic Search

This patent describes a reciprocating internal combustion engine of the type having an engine block means defining at least one cylinder with an associate pair of ports, a valve located for axial movement in each of the ports with each valve normally biased to a valve closed position relative to its associate port. A rocker shaft support means is fixed

Derringer

1986-01-01

2

Diagnostic for two-mode variable valve activation device  

DOEpatents

A method is provided for diagnosing a multi-mode valve train device which selectively provides high lift and low lift to a combustion valve of an internal combustion engine having a camshaft phaser actuated by an electric motor. The method includes applying a variable electric current to the electric motor to achieve a desired camshaft phaser operational mode and commanding the multi-mode valve train device to a desired valve train device operational mode selected from a high lift mode and a low lift mode. The method also includes monitoring the variable electric current and calculating a first characteristic of the parameter. The method also includes comparing the calculated first characteristic against a predetermined value of the first characteristic measured when the multi-mode valve train device is known to be in the desired valve train device operational mode.

Fedewa, Andrew M

2014-01-07

3

Valve train calculation model with regard to oil film effects  

Microsoft Academic Search

A mathematical equivalent model to describe the dynamic behaviour of mechanical actuated valve trains has been developed which is based on a multidegrees-of-freedom vibratory system. It could be shown that dampings and stiffnesses efficient in a valve train are influenced by three oil film effects: these are squeeze films between the valve train components, elastohydrodynamic lubrication of cam and follower

P. Kreuter; F. Pischinger

1985-01-01

4

Remotely-Controlled Variable-Orifice Valve  

NASA Technical Reports Server (NTRS)

Remotely-controlled variable-orifice valve used to adjust back pressure in tests of flow of air in duct. Disk with holes rotated on fixed disk with similiar holes to adjust cross sectional area available to flow. Features include compactness and reduction of perturbation. Moved easily from one flow-test facility to another.

Hill, Olen E.

1990-01-01

5

Turbo-generator control with variable valve actuation  

DOEpatents

An internal combustion engine incorporating a turbo-generator and one or more variably activated exhaust valves. The exhaust valves are adapted to variably release exhaust gases from a combustion cylinder during a combustion cycle to an exhaust system. The turbo-generator is adapted to receive exhaust gases from the exhaust system and rotationally harness energy therefrom to produce electrical power. A controller is adapted to command the exhaust valve to variably open in response to a desired output for the turbo-generator.

Vuk, Carl T. (Denver, IA)

2011-02-22

6

Selecting control and balancing valves in a variable flow system  

SciTech Connect

This article describes the design and selection of control and balancing valves in a hydronic variable flow system consisting of 100 load terminals for providing cooling to a building. The author addresses approaching a linear terminal emission over the valve operating range, minimizing pump head and operating horsepower, proportioning the flow to each terminal and zone, balancing tests, and instrumentation.

Hegberg, R.A.

1997-06-01

7

Engine having a variable valve actuation system  

SciTech Connect

An engine has a cylinder head having a first surface and a second surface spaced from the first surface. A valve is moveably connected to the cylinder head. A rocker arm is connected to the valve, and a rocker shaft having a first location spaced a maximum distance from the cylinder head is connected to the rocker arm. A support member has and an actuator fluid passage network. The actuator fluid passage network defines a volume. The support member is connected to the cylinder head and is positioned such that a majority of the volume of the actuator fluid passage network is between the first location of the rocker shaft and the second surface of the cylinder head.

Hefler, Gregory W. (Chillicothe, IL)

2005-10-12

8

Engine having a variable valve actuation system  

SciTech Connect

An engine has a cylinder head having a first surface and a second surface spaced from the first surface. A valve is moveably connected to the cylinder head. A rocker arm is connected to the valve, and a rocker shaft having a first location spaced a maximum distance from the cylinder head is connected to the rocker arm. A support member has and an actuator fluid passage network. The actuator fluid passage network defines a volume. The support member is connected to the cylinder head and is positioned such that a majority of the volume of the actuator fluid passage network is between the first location of the rocker shaft and the second surface of the cylinder head.

Hefler, Gregory W. (Chillicothe, IL)

2004-10-12

9

Advanced Technology Training System on Motor-Operated Valves  

NASA Technical Reports Server (NTRS)

This paper describes how features from the field of Intelligent Tutoring Systems are applied to the Motor-Operated Valve (MOV) Advanced Technology Training System (ATTS). The MOV ATTS is a training system developed at Galaxy Scientific Corporation for the Central Research Institute of Electric Power Industry in Japan and the Electric Power Research Institute in the United States. The MOV ATTS combines traditional computer-based training approaches with system simulation, integrated expert systems, and student and expert modeling. The primary goal of the MOV ATTS is to reduce human errors that occur during MOV overhaul and repair. The MOV ATTS addresses this goal by providing basic operational information of the MOV, simulating MOV operation, providing troubleshooting practice of MOV failures, and tailoring this training to the needs of each individual student. The MOV ATTS integrates multiple expert models (functional and procedural) to provide advice and feedback to students. The integration also provides expert model validation support to developers. Student modeling is supported by two separate student models: one model registers and updates the student's current knowledge of basic MOV information, while another model logs the student's actions and errors during troubleshooting exercises. These two models are used to provide tailored feedback to the student during the MOV course.

Wiederholt, Bradley J.; Widjaja, T. Kiki; Yasutake, Joseph Y.; Isoda, Hachiro

1993-01-01

10

Valve  

Microsoft Academic Search

A valve device is described for controlling the flow of fuel to an internal combustion engine having a pressurized lubricating oil system associated therewith. The valve is adapted to be disposed in the fuel line between a fuel pump and the engine. The device comprises a valve body having a bore with an axis therein, a pair of fuel inlet

1986-01-01

11

Closed-loop, variable-valve-timing control of a controlled-auto-ignition engine  

E-print Network

The objective of this study was to develop a closed-loop controller for use on a Controlled-Auto- Ignition (CAI) / Spark-Ignition (SI) mixed mode engine equipped with a variable-valve-timing (VVT) mechanism. The controller ...

Matthews, Jeffrey A., 1970-

2004-01-01

12

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

SciTech Connect

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

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

1994-11-18

13

Artificial neural-network based modeling of variable valve-timing in a spark-ignition engine  

Microsoft Academic Search

Variable valve-timing and lift are significant operating and design parameters affecting the performance and emissions in spark-ignition (SI) engines. Previous investigations have demonstrated that improvements in engine performance can be accomplished if the valve timing is variable. Traditionally, valve timing has been designed to optimize operation at high engine-speed and wide-open throttle conditions. Controlling valve timing can improve the torque

Mustafa Gölcü; Yakup Sekmen; Perihan Erduranl?; M. Sahir Salman

2005-01-01

14

Valve  

DOEpatents

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

Cho, Nakwon (Knoxville, TN)

1980-01-01

15

Effect Analysis of Design Variables on the Disc in a Double-Eccentric Butterfly Valve  

PubMed Central

We have performed a shape optimization of the disc in an industrial double-eccentric butterfly valve using the effect analysis of design variables to enhance the valve performance. For the optimization, we select three performance quantities such as pressure drop, maximum stress, and mass (weight) as the responses and three dimensions regarding the disc shape as the design variables. Subsequently, we compose a layout of orthogonal array (L16) by performing numerical simulations on the flow and structure using a commercial package, ANSYS v13.0, and then make an effect analysis of the design variables on the responses using the design of experiments. Finally, we formulate a multiobjective function consisting of the three responses and then propose an optimal combination of the design variables to maximize the valve performance. Simulation results show that the disc thickness makes the most significant effect on the performance and the optimal design provides better performance than the initial design. PMID:24883380

Kim, Da-Eun; Kim, Kuk-Kyeom; Kim, Jun-Oh

2014-01-01

16

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

DOEpatents

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

Hansen, Craig N. (Eden Prairie, MN); Cross, Paul C. (Shorewood, MN)

1995-01-01

17

Working characteristics of variable intake valve in compressed air engine.  

PubMed

A new camless compressed air engine is proposed, which can make the compressed air energy reasonably distributed. Through analysis of the camless compressed air engine, a mathematical model of the working processes was set up. Using the software MATLAB/Simulink for simulation, the pressure, temperature, and air mass of the cylinder were obtained. In order to verify the accuracy of the mathematical model, the experiments were conducted. Moreover, performance analysis was introduced to design compressed air engine. Results show that, firstly, the simulation results have good consistency with the experimental results. Secondly, under different intake pressures, the highest output power is obtained when the crank speed reaches 500 rpm, which also provides the maximum output torque. Finally, higher energy utilization efficiency can be obtained at the lower speed, intake pressure, and valve duration angle. This research can refer to the design of the camless valve of compressed air engine. PMID:25379536

Yu, Qihui; Shi, Yan; Cai, Maolin

2014-01-01

18

Spool-type control valve assembly with reduced spool stroke for hydraulic belt-and-pulley type continuously variable transmission  

SciTech Connect

This patent describes a hydraulic control system for controlling a speed ratio of a hydraulically-operated continuously variable transmission of belt-and-pulley type having a variable-diameter pulley and a hydraulic cylinder for changing an effective diameter of the variable diameter-pulley of the transmission. The hydraulic control system includes a speed-ratio control valve assembly for controlling the supply and discharge of a pressurized fluid to and from the hydraulic cylinder to thereby change the speed ratio of the transmission. The speed-ratio control valve assembly comprises: a shift-direction switching valve unit disposed in fluid supply and discharge conduits communicating with the hydraulic cylinder, for controlling a direction in which the speed ratio of the transmission is varied; a shift-speed control valve unit of spool-valve type connected to the shift-direction switching valve unit. The shift-speed control valve unit is selectively placed in a first state in which the fluid supply and discharge flows to and from the hydraulic cylinder through the conduits are permitted, or in a second state in which the fluid supply flow is restricted while the fluid discharge flow is inhibited; an actuator means for placing the shift speed control valve unit alternately in the first and second states to control a rate of variation in the speed ratio of the transmission in the direction established by the shift-direction switching valve unit.

Itoh, H.; Akashi, T.; Takada, M.

1987-03-31

19

Critical Variables in Training Early Childhood Special Educators.  

ERIC Educational Resources Information Center

This paper attempts to identify critical variables for designing training programs in early childhood special education. A literature review is presented on training and the adult learner. Important characteristics of training are identified, such as the course design, sequence, content, and adult learning strategies used. Other significant…

Bennett, Teresa C.

20

Control valve system for a continuously variable belt driven transmission for motor vehicles  

SciTech Connect

This patient describes a hydraulic valve system for controlling a continuously variable drive ratio automotive vehicle transmission adapted to shift continuously between different drive ratios and having first and second control pulleys driveably connected by an endless traction belt, a displacement cylinder associated with each pulley, the location of the belt on each pulley being radially variable in response to hydraulic fluid pressure in the associated cylinder to shift between the drive ratios, comprising; first and second hydraulic fluid pumps; main pressure regulation valve means connected to the discharge of the second pump for producing line pressure and torque converter supply pressure; torque converter means for hydrodynamically, driveably connecting the engine of the vehicle to a transmission pulley, the torque converter means having an impeller, a turbine, the impeller connected to the engine, the turbine connected to the pulley; a lockup clutch adapted to selectively driveably connect the turbine and the impeller when hydraulic fluid flows in a first direction through the torque converter and to disconnect the turbine and impeller when the flow is in the opposite direction; a lockup valve supplied with line pressure, coupled to the electronic control means for opening and closing communication between line pressure and a converter lockup pressure line in accordance with the control of the electronic control.

Eggert, U.; Staffel, H.

1988-12-13

21

Torque Control for Automotive Engines with Variable Valves via Air and Burned Gas Flow-Based Design  

NASA Astrophysics Data System (ADS)

This paper proposes a predictive control method for automotive engines with variable valves. The control purpose is to track not only the torque reference but also the pressure reference of the surge tank in consideration for the constraint of internal exhaust gas recirculation ratio. The control inputs are the throttle angle and the intake valve lift, however, the proposed control method is based on a flow model where the mass flows through the throttle and the intake valves are regarded as the virtual control inputs. The controller designed for the SICE benchmark engine is validated by numerical simulations.

Jimbo, Tomohiko; Hayakawa, Yoshikazu

22

A fault diagnosis approach for diesel engine valve train based on improved ITD and SDAG-RVM  

NASA Astrophysics Data System (ADS)

Targeting the non-stationary characteristics of the vibration signals of a diesel engine valve train, and the limitation of the autoregressive (AR) model, a novel approach based on the improved intrinsic time-scale decomposition (ITD) and relevance vector machine (RVM) is proposed in this paper for the identification of diesel engine valve train faults. The approach mainly consists of three stages: First, prior to the feature extraction, non-uniform B-spline interpolation is introduced to the ITD method for the fitting of baseline signal, then the improved ITD is used to decompose the non-stationary signals into a set of stationary proper rotation components (PRCs). Second, the AR model is established for each PRC, and the first several AR coefficients together with the remnant variance of all PRCs are regarded as the fault feature vectors. Finally, a new separability based directed acyclic graph (SDAG) method is proposed to determine the structure of multi-class RVM, and the fault feature vectors are classified using the SDAG-RVM classifier to recognize the fault of the diesel engine valve train. The experimental results demonstrate that the proposed fault diagnosis approach can effectively extract the fault features and accurately identify the fault patterns.

Yu, Liu; Junhong, Zhang; Fengrong, Bi; Jiewei, Lin; Wenpeng, Ma

2015-02-01

23

Variable stiffness and damping suspension system for train  

NASA Astrophysics Data System (ADS)

As the vibration of high speed train becomes fierce when the train runs at high speed, it is crucial to develop a novel suspension system to negotiate train's vibration. This paper presents a novel suspension based on Magnetorheological fluid (MRF) damper and MRF based smart air spring. The MRF damper is used to generate variable damping while the smart air spring is used to generate field-dependent stiffness. In this paper, the two kind smart devices, MRF dampers and smart air spring, are developed firstly. Then the dynamic performances of these two devices are tested by MTS. Based on the testing results, the two devices are equipped to a high speed train which is built in ADAMS. The skyhook control algorithm is employed to control the novel suspension. In order to compare the vibration suppression capability of the novel suspension with other kind suspensions, three other different suspension systems are also considered and simulated in this paper. The other three kind suspensions are variable damping with fixed stiffness suspension, variable stiffness with fixed damping suspension and passive suspension. The simulation results indicate that the variable damping and stiffness suspension suppresses the vibration of high speed train better than the other three suspension systems.

Sun, Shuaishuai; Deng, Huaxia; Li, Weihua

2014-03-01

24

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

PubMed

A novel solution for electro-hydraulic variable valve timing (VVT) system of gasoline engines is proposed, based on the concept of active disturbance rejection control (ADRC). Disturbances, such as oil pressure and engine speed variations, are all estimated and mitigated in real-time. A feed-forward controller was added to enhance the performance of the system based on a simple and static first principle model, forming a hybrid disturbance rejection control (HDRC) strategy. HDRC was validated by experimentation and compared with an existing manually tuned proportional-integral (PI) controller. The results show that HDRC provided a faster response and better tolerance of engine speed and oil pressure variations. PMID:24238361

Xie, Hui; Song, Kang; He, Yu

2014-07-01

25

Zebra tape identification for the instantaneous angular speed computation and angular resampling of motorbike valve train measurements  

NASA Astrophysics Data System (ADS)

An experimental test campaign was performed on the valve train of a racing motorbike engine in order to get insight into the dynamic of the system. In particular the valve motion was acquired in cold test conditions by means of a laser vibrometer able to acquire displacement and velocity signals. The valve time-dependent measurements needed to be referred to the camshaft angular position in order to analyse the data in the angular domain, as usually done for rotating machines. To this purpose the camshaft was fitted with a zebra tape whose dark and light stripes were tracked by means of an optical probe. Unfortunately, both manufacturing and mounting imperfections of the employed zebra tape, resulting in stripes with slightly different widths, precluded the possibility to directly obtain the correct relationship between camshaft angular position and time. In order to overcome this problem, the identification of the zebra tape was performed by means of the original and practical procedure that is the focus of the present paper. The method consists of three main steps: namely, an ad-hoc test corresponding to special operating conditions, the computation of the instantaneous angular speed, and the final association of the stripes with the corresponding shaft angular position. The results reported in the paper demonstrate the suitability of the simple procedure for the zebra tape identification performed with the final purpose to implement a computed order tracking technique for the data analysis.

Rivola, Alessandro; Troncossi, Marco

2014-02-01

26

On the risk of aortic valve replacement surgery assessed by heart rate variability parameters.  

PubMed

In recent years the number of arterial stenosis (AS) patients has grown rapidly and valvular disease is expected to be the next great epidemic. We studied a group of 385 arterial valve replacement (AVR) surgery patients, of whom 16 had died in the postoperational period (up to 30?d after the operation). Each patient had a heart rate variability (HRV) recording made prior to the operation in addition to a full set of medical diagnostics including echocardiography. We formed 16 age, sex, New York Heart Association (NYHA) class, and BMI adjusted control pairs for each person who died in the perioperative period. Our aim was to find indications of the risk from AVR surgery based on the medical data and HRV properties. Besides standard, linear HRV methods, we used indexes of time irreversibility introduced by Guzik (G%), Porta (P%), Ehlers (index E) and Hou (index D). In addition, we analyzed the multiscale multifractal properties of HRV calculating the Hurst surface. The nonlinear analysis methods show statistically significant indications of the risk of AVR surgery in an increase of multifractality and an increase of time irreversibility of the HRV measured prior to the operation. PMID:25514504

Zebrowski, J J; Kowalik, I; Or?owska-Baranowska, E; Andrzejewska, M; Baranowski, R; Giera?towski, J

2015-01-01

27

Cycle-to-cycle variation analysis of in-cylinder flow in a gasoline engine with variable valve lift  

NASA Astrophysics Data System (ADS)

In spark ignition engines, cycle-to-cycle variation (CCV) limits the expansion of the operating range because it induces the load variations and the occurrence of misfire and/or knock. Variable valve actuation (VVA) or variable valve lift (VVL) has been widely used in SI engines to improve the volumetric efficiency or to reduce the pumping losses. It is necessary to investigate the CCV of in-cylinder gas motion and mixing processes in SI engines with VVA/VVL system. This study is aimed to analyze the CCV of the tumble flow in a gasoline direct injection (GDI) engine when VVL is employed. Cycle-resolved digital particle image velocimetry (CRD-PIV) data were acquired for the in-cylinder flow field of a motored four-stroke multi-valve GDI optical engine. The CCV of in-cylinder gas motion with a series of valve profiles and different maximum valve lift (MVL) was analyzed, including cyclic variation characteristics of bulk flow (tumble centre and tumble ratio), large- and small-scale fluctuation, total kinetic energy, and circulation. The results show that the CCV of the in-cylinder flow is increased with reduced MVL. With lower MVLs, stable tumble flow cannot be formed in the cylinder, and the ensemble-averaged tumble ratio decreases to zero before the end of the compression stroke due to violent variation. In addition, the evolution of the circulation shows larger variation with lower MVLs that indicates the `spin' of the small-scale eddy in the flow field presents violent fluctuation from one cycle to another, especially at the end of the compression stroke. Moreover, the analyze of the kinetic energy indicates the total energy of the flow field with lower MVLs increases significantly comparing with higher MVL conditions due to the intake flow jet at the intake valve seat in the intake stroke. However, the CCV of the in-cylinder flow becomes more violent under lower MVL conditions, especially for the low-frequency fluctuation kinetic energy. Thus, present strong tumble flow can lower the CCV of the air motion. It is necessary to manage strong tumble or other bulk flow (such as swirl flow) in order to improve the stability of ignition and combustion for GDI engines with VVL, especially at the lower MVL conditions.

Liu, Daming; Wang, Tianyou; Jia, Ming; Wang, Gangde

2012-09-01

28

Spike-Train Variability of Auditory Neurons In Vivo: Dynamic Responses Follow Predictions From Constant Stimuli  

E-print Network

Spike-Train Variability of Auditory Neurons In Vivo: Dynamic Responses Follow Predictions From January 2005 Schaette, Roland, Tim Gollisch, and Andreas V. M. Herz. Spike-train variability of auditory ob- served in neural spike trains are a prerequisite for the proper inter- pretation of neural

Gollisch, Tim

29

Neuromuscular adaptations to constant vs. variable resistance training in older men.  

PubMed

This study examined the effects of constant or variable external resistance training on neuromuscular adaptations in the lower limbs of older men. 37 subjects (age 65±4?year) were quasi-randomly assigned to the constant or variable training group, or a non-training control group. Training consisted of a 20-week medium-intensity, high volume resistance training program. Maximum bilateral concentric and isometric force production of the leg extensors as well as repetitions-to-failure test were performed pre-, mid- and post-training. Vastus lateralis muscle cross-sectional area was assessed by ultrasound and lean leg mass was assessed by dual-energy x-ray absorptiometry. Both training groups significantly increased force production of the leg extensors (variable: 26?kg, 95% CI=12-39, P<0.01; constant: 31?kg, 95% CI=19-43, P<0.01) and VL cross-sectional area (variable: 1.5?cm2, 95% CI=0.03-3.1, P=0.046; constant: 3?cm2, 95% CI=1.2-4.8, P=0.002). However, only the variable training group significantly improved repetitions to failure performance (704?kg, 95% CI=45-1?364, P=0.035). Only the variable resistance training group improved fatigue-resistance properties, which may be an important adaptation to maintain exercise and functional capacity in older individuals. PMID:23825004

Walker, S; Peltonen, H; Sautel, J; Scaramella, C; Kraemer, W J; Avela, J; Häkkinen, K

2014-01-01

30

Perceived exertion responses to changing resistance training programming variables.  

PubMed

This study examined the influence of intensity (%1RM), tonnage (sets x repetitions x load), rate of fatigue (percentage decrement in repetitions from set-to-set), work rate (total tonnage per unit of time), rest interval (time between sets), time under load, and session duration on session rating of perceived exertion (sRPE: Borg CR-10 scale). Here, participants performed a standardised lifting session of five exercises (bench press, leg press, lat pulldown, leg curl and triceps pushdown) as either: A) 3 sets x 8 repetitions x 3 min recovery at 70% 1RM; B) 3 sets x 14 repetitions x 3 min recovery at 40% 1RM; C) 3 sets x MNR (maximum number of repetitions) x 1 min recovery at 70% 1RM; D) 3 sets x MNR x 3 min recovery at 70% 1RM; E) 3 sets x MNR x 1 min recovery at 40% 1RM; or F) 3 sets x MNR x 3 min recovery at 40% 1RM. The sRPE for session A (4 ± 1) was significantly higher than session B (2.5 ± 1), despite matched tonnage. Protocols involving MNR showed no significant difference in sRPE. Work rate was the only variable to significantly relate with sRPE (r = 0.45). Additionally, sRPE at 15 min post-exercise (5 ± 2) was not different to 30 min post-exercise (5 ± 2). In resistance training with matched tonnage and rest duration between sets, sRPE increases with intensity. In sets to volitional failure, sRPE is likely to be similar, regardless of intensity or rest duration between sets. PMID:25436635

Hiscock, Daniel J; Dawson, Brian; Peeling, Peter

2014-11-26

31

Spray characterization of flex-fuel gasoline di injectors and spray interaction with charge motion in a variable valve actuation engine  

Microsoft Academic Search

The objective of this study is to understand the characteristics of GDI sprays and behavior of in-cylinder charge motion in a GDI engine which is equipped with variable valve actuation. High speed spray visualization in a spray chamber was conducted for a study of spray development. By Schlieren visualization technique, the effect of different conditions including ambient conditions (temperature, pressure)

Atsushi Matsumoto

2012-01-01

32

Spray characterization of flex-fuel gasoline DI injectors and spray interaction with charge motion in a variable valve actuation engine  

Microsoft Academic Search

The objective of this study is to understand the characteristics of GDI sprays and behavior of in-cylinder charge motion in a GDI engine which is equipped with variable valve actuation. High speed spray visualization in a spray chamber was conducted for a study of spray development. By Schlieren visualization technique, the effect of different conditions including ambient conditions (temperature, pressure)

Atsushi Matsumoto

2012-01-01

33

Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training  

PubMed Central

Endurance athletes integrate four conditioning concepts in their training programs: high-volume training (HVT), “threshold-training” (THR), high-intensity interval training (HIIT) and a combination of these aforementioned concepts known as polarized training (POL). The purpose of this study was to explore which of these four training concepts provides the greatest response on key components of endurance performance in well-trained endurance athletes. Methods: Forty eight runners, cyclists, triathletes, and cross-country skiers (peak oxygen uptake: (VO2peak): 62.6 ± 7.1 mL·min?1·kg?1) were randomly assigned to one of four groups performing over 9 weeks. An incremental test, work economy and a VO2peak tests were performed. Training intensity was heart rate controlled. Results: POL demonstrated the greatest increase in VO2peak (+6.8 ml·min·kg?1 or 11.7%, P < 0.001), time to exhaustion during the ramp protocol (+17.4%, P < 0.001) and peak velocity/power (+5.1%, P < 0.01). Velocity/power at 4 mmol·L?1 increased after POL (+8.1%, P < 0.01) and HIIT (+5.6%, P < 0.05). No differences in pre- to post-changes of work economy were found between the groups. Body mass was reduced by 3.7% (P < 0.001) following HIIT, with no changes in the other groups. With the exception of slight improvements in work economy in THR, both HVT and THR had no further effects on measured variables of endurance performance (P > 0.05). Conclusion: POL resulted in the greatest improvements in most key variables of endurance performance in well-trained endurance athletes. THR or HVT did not lead to further improvements in performance related variables. PMID:24550842

Stöggl, Thomas; Sperlich, Billy

2014-01-01

34

Safety valve  

DOEpatents

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

Bergman, Ulf C. (Malmoe, SE)

1984-01-01

35

DETERMINING VARIABLES OF PLYOMETRIC TRAINING FOR IMPROVING VERTICAL JUMP HEIGHT PERFORMANCE: AM ETA-ANALYSIS  

Microsoft Academic Search

Saez Saez de Villarreal, E, Kellis, E, Kraemer, WJ, and Izquierdo, M. Determining variables of plyometric training for improving vertical jump height performance: a meta-analysis. J Strength Cond Res 23(2): xxx-xxx, 2009—Plyometric training improves vertical jump height (VJH). However, the effectiveness of plyometric training depends on various factors. A meta-analysis of 56 studies with a total of 225 effect sizes

EDUARDO SAEZ-SAEZ DE VILLARREAL; ELEFTHERIOS KELLIS; WILLIAM J. KRAEMER; MIKEL IZQUIERDO

36

Exercise Training in Athletes with Bicuspid Aortic Valve Does Not Result in Increased Dimensions and Impaired Performance of the Left Ventricle  

PubMed Central

Background. Bicuspid aortic valve (BAV) is one of the most common congenital heart disease (0.9%–2%) and is frequently found in the athletes and in the general population. BAV can lead to aortic valve dysfunction and to a progressive aortic dilatation. Trained BAV athletes exhibit a progressive enlargement of the left ventricle (LV) compared to athletes with normal aortic valve morphology. The present study investigates the possible relationship between different aortic valve morphology and LV dimensions. Methods. In the period from 2000 to 2011, we investigated a total of 292 BAV subjects, divided into three different groups (210 athletes, 59 sedentaries, and 23 ex-athletes). A 2D echocardiogram exam to classify BAV morphology and measure the standard LV systo-diastolic parameters was performed. The study was conducted as a 5-year follow-up echocardiographic longitudinal and as cross-sectional study. Results. Typical BAV was more frequent in all three groups (68% athletes, 67% sedentaries, and 63% ex-athletes) than atypical. In BAV athletes, the typical form was found in 51% (107/210) of soccer players, 10% (21/210) of basketball players, 10% track and field athletics (20/210), 8% (17/210) of cyclists, 6% (13/210) swimmers, and 15% (32/210) of rugby players and others sport. Despite a progressive enlargement of the LV (P < 0.001) observed during the follow-up study, no statistical differences of the LV morphology and function were evident among the diverse BAV patterns either in sedentary subjects or in athletes. Conclusion. In a large population of trained BAV athletes, with different prevalence of typical and atypical BAV type, there is a progressive nonstatistically significant enlargement of the LV. In any case, the dimensions of the LV remained within normal range. The metabolic requirements of the diverse sport examined in the present investigations do not seem to produce any negative impact in BAV athletes PMID:24600528

Stefani, Laura; Galanti, Giorgio; Innocenti, Gabriele; Mercuri, Roberto; Maffulli, Nicola

2014-01-01

37

Cognitive Styles: The Unaccommodated Variable in Training Design Decisions.  

ERIC Educational Resources Information Center

Discusses effects of student and teacher cognitive styles on teacher/learner relationships and on training transactions, suggesting that teachers and students with like cognitive styles interact more successfully and that field-dependent learners, who tend to favor working alone, perform better with self-paced instruction. Instructional design…

Wallace, Squy G.; Gregory, Russell A.

1985-01-01

38

Anthropometric and training variables related to 10km running performance.  

PubMed Central

Sixty male distance athletes were divided into three equal groups according to their personal best time for the 10km run. The runners were measured anthropometrically and each runner completed a detailed questionnaire on his athletic status, training programme and performance. The runners in this study had similar anthropometric and training profiles to other distance runners of a similar standard. The most able runners were shorter and lighter than those in the other two groups and significantly smaller skinfold values (P less than 0.05). There were no significant differences between the groups for either bone widths or circumferences but the elite and good runners had significantly higher ponderal indices (P less than 0.05) than the average runners, indicating that they are more linear. Elite and good runners were also less endomorphic but more ectomorphic than the average runners. The elite runners trained more often, ran more miles per week and had been running longer (P less than 0.05) than good or average runners. A multiple regression and discriminant function analysis indicated that linearity, total skinfold, the type and frequency of training and the number of years running were the best predictors of running performance and success at the 10km distance. PMID:3814989

Bale, P; Bradbury, D; Colley, E

1986-01-01

39

Engine air intake valve  

Microsoft Academic Search

This paper discusses, in combination with an internal combustion engine, a system for regulating engine speed by regulating the air flow across a throttle valve in an air intake passage. It comprises an engine air intake valve and means of sensing an operating variable representative of engine speed and sending an electrical signal representative of the engine speed to the

1990-01-01

40

Promoting Response Variability and Stimulus Generalization in Martial Arts Training  

ERIC Educational Resources Information Center

The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack.…

Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Rick, Gary; Lee, John F.

2004-01-01

41

The Effect of Literacy Training on Modernization Variables.  

ERIC Educational Resources Information Center

The present research was a field experiment exploring the relationship of literacy to certain modernization variables. Data were collected in five rural communities in Minas Gerais, Brazil, in July 1966. The communities were matched as closely as possible on population, literacy rate, distance to an urban center, community institutional…

Herzog, William Adam, Jr.

42

Limit-push training reduces motor variability Department of Bioengineering  

E-print Network

individuals, who exhibit the commonly seen motor deficits of large trial to trial variability, such as victims of stroke and traumatic brain injury. I. INTRODUCTION A number of recent studies have shown remarkable restore function to brain injured individuals. However, little attention has been given using

Patton, James

43

Promoting response variability and stimulus generalization in martial arts training.  

PubMed Central

The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack. During baseline, the students received no feedback on their responses in either condition. During the intervention phase, the students received differential reinforcement in the form of instructor feedback for each different punching or kicking technique they performed during a session of the drill condition, but no reinforcement was provided for techniques in the sparring condition. Results showed that both students increased the number of different techniques they performed when reinforcement and extinction procedures were conducted during the drill condition, and that this increase in response variability generalized to the sparring condition. PMID:15293637

Harding, Jay W; Wacker, David P; Berg, Wendy K; Rick, Gary; Lee, John F

2004-01-01

44

Prediction of space sickness in astronauts from preflight fluid, electrolyte, and cardiovascular variables and Weightless Environmental Training Facility (WETF) training  

NASA Technical Reports Server (NTRS)

Nine preflight variables related to fluid, electrolyte, and cardiovascular status from 64 first-time Shuttle crewmembers were differentially weighted by discrimination analysis to predict the incidence and severity of each crewmember's space sickness as rated by NASA flight surgeons. The nine variables are serum uric acid, red cell count, environmental temperature at the launch site, serum phosphate, urine osmolality, serum thyroxine, sitting systolic blood pressure, calculated blood volume, and serum chloride. Using two methods of cross-validation on the original samples (jackknife and a stratefied random subsample), these variables enable the prediction of space sickness incidence (NONE or SICK) with 80 percent sickness and space severity (NONE, MILD, MODERATE, of SEVERE) with 59 percent success by one method of cross-validation and 67 percent by another method. Addition of a tenth variable, hours spent in the Weightlessness Environment Training Facility (WETF) did not improve the prediction of space sickness incidences but did improve the prediction of space sickness severity to 66 percent success by the first method of cross-validation of original samples and to 71 percent by the second method. Results to date suggest the presence of predisposing physiologic factors to space sickness that implicate fluid shift etiology. The data also suggest that prior exposure to fluid shift during WETF training may produce some circulatory pre-adaption to fluid shifts in weightlessness that results in a reduction of space sickness severity.

Simanonok, K.; Mosely, E.; Charles, J.

1992-01-01

45

Aortic Valve  

MedlinePLUS

... in this category include " xenograft " valves made from animal tissues (most often pig aortic valves), " homograft " or " allograft " valves retrieved from human cadavers, and " pulmonary autograft " valves moved from the patient's pulmonary artery on the right side of the heart to the aortic position ...

46

Moderating variables of music training-induced neuroplasticity: a review and discussion.  

PubMed

A large body of literature now exists to substantiate the long-held idea that musicians' brains differ structurally and functionally from non-musicians' brains. These differences include changes in volume, morphology, density, connectivity, and function across many regions of the brain. In addition to the extensive literature that investigates these differences cross-sectionally by comparing musicians and non-musicians, longitudinal studies have demonstrated the causal influence of music training on the brain across the lifespan. However, there is a large degree of inconsistency in the findings, with discordance between studies, laboratories, and techniques. A review of this literature highlights a number of variables that appear to moderate the relationship between music training and brain structure and function. These include age at commencement of training, sex, absolute pitch (AP), type of training, and instrument of training. These moderating variables may account for previously unexplained discrepancies in the existing literature, and we propose that future studies carefully consider research designs and methodologies that control for these variables. PMID:24058353

Merrett, Dawn L; Peretz, Isabelle; Wilson, Sarah J

2013-01-01

47

Moderating variables of music training-induced neuroplasticity: a review and discussion  

PubMed Central

A large body of literature now exists to substantiate the long-held idea that musicians' brains differ structurally and functionally from non-musicians' brains. These differences include changes in volume, morphology, density, connectivity, and function across many regions of the brain. In addition to the extensive literature that investigates these differences cross-sectionally by comparing musicians and non-musicians, longitudinal studies have demonstrated the causal influence of music training on the brain across the lifespan. However, there is a large degree of inconsistency in the findings, with discordance between studies, laboratories, and techniques. A review of this literature highlights a number of variables that appear to moderate the relationship between music training and brain structure and function. These include age at commencement of training, sex, absolute pitch (AP), type of training, and instrument of training. These moderating variables may account for previously unexplained discrepancies in the existing literature, and we propose that future studies carefully consider research designs and methodologies that control for these variables. PMID:24058353

Merrett, Dawn L.; Peretz, Isabelle; Wilson, Sarah J.

2013-01-01

48

Effect of Training on Physiological and Biochemical Variables of Soccer Players of Different Age Groups  

PubMed Central

Purpose To find out the effect of training on selected physiological and biochemical variables of Indian soccer players of different age groups. Methods A total of 120 soccer players volunteered for the study, were divided (n = 30) into 4 groups: (i) under 16 years (U16), (ii) under 19 years (U19), (iii) under 23 years (U23), (iv) senior (SR). The training sessions were divided into 2 phases (a) Preparatory Phase (PP, 8 weeks) and (b) Competitive Phase (CP, 4 weeks). The training program consisted of aerobic, anaerobic and skill development, and were completed 4 hrs/day; 5 days/week. Selected physiological and biochemical variables were measured at zero level (baseline data, BD) and at the end of PP and CP. Results A significant increase (P < 0.05) in lean body mass (LBM), VO2max, anaerobic power, grip and back strength, urea, uric acid and high density lipoprotein cholesterol (HDL-C); and a significant decrease (P < 0.05) in body fat, hemoglobin (Hb), total cholesterol (TC), triglyceride (TG) and low density lipoprotein cholesterol (LDL-C) were detected in some groups in PP and CP phases of the training when compare to BD. However, no significant change was found in body mass and maximal heart rate of the players after the training program. Conclusion This study would provide useful information for training and selection of soccer players of different age groups. PMID:22375187

Manna, Indranil; Khanna, Gulshan Lal; Chandra Dhara, Prakash

2010-01-01

49

Training the max-margin sequence model with the relaxed slack variables.  

PubMed

Sequence models are widely used in many applications such as natural language processing, information extraction and optical character recognition, etc. We propose a new approach to train the max-margin based sequence model by relaxing the slack variables in this paper. With the canonical feature mapping definition, the relaxed problem is solved by training a multiclass Support Vector Machine (SVM). Compared with the state-of-the-art solutions for the sequence learning, the new method has the following advantages: firstly, the sequence training problem is transformed into a multiclassification problem, which is more widely studied and already has quite a few off-the-shelf training packages; secondly, this new approach reduces the complexity of training significantly and achieves comparable prediction performance compared with the existing sequence models; thirdly, when the size of training data is limited, by assigning different slack variables to different microlabel pairs, the new method can use the discriminative information more frugally and produces more reliable model; last but not least, by employing kernels in the intermediate multiclass SVM, nonlinear feature space can be easily explored. Experimental results on the task of named entity recognition, information extraction and handwritten letter recognition with the public datasets illustrate the efficiency and effectiveness of our method. PMID:22717449

Niu, Lingfeng; Wu, Jianmin; Shi, Yong

2012-09-01

50

Supercharged two-cycle engines employing novel single element reciprocating shuttle inlet valve mechanisms and with a variable compression ratio  

NASA Technical Reports Server (NTRS)

This invention relates to novel reciprocating shuttle inlet valves, effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines, employing spark or compression ignition. Also permitting the elimination of out-of-phase piston arrangements to control scavenging and supercharging of opposed-piston engines. The reciprocating shuttle inlet valve (32) and its operating mechanism (34) is constructed as a single and simple uncomplicated member, in combination with the lost-motion abutments, (46) and (48), formed in a piston skirt, obviating the need for any complex mechanisms or auxiliary drives, unaffected by heat, friction, wear or inertial forces. The reciprocating shuttle inlet valve retains the simplicity and advantages of two-cycle engines, while permitting an increase in volumetric efficiency and performance, thereby increasing the range of usefulness of two-cycle engines into many areas that are now dominated by the four-cycle engine.

Wiesen, Bernard (Inventor)

2008-01-01

51

Check valve  

DOEpatents

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

Upton, H.A.; Garcia, P.

1999-08-24

52

Interactive Effects of Environmental Variability and Military Training on Stream Biota of Three Headwater Drainages in Western Louisiana  

Microsoft Academic Search

We collected fishes and macroinvertebrates seasonally from eight headwater streams in three different drainage basins (the Red, Calcasieu, and Sabine rivers) crossing Peason Ridge Training Area in west-central Louisiana. Peason Ridge is part of the Fort Polk military training facility. We used multivariate analyses to test the effects of physical variables (i.e., current velocity, depth, and substrate), time (seasonal variability),

Lance R. Williams; Timothy H. Bonner; James D. Hudson III; Marsha G. Williams; Tracy R. Leavy; Casey S. Williams

2005-01-01

53

Venous Valves  

NSDL National Science Digital Library

This simple FlashTM animation depicts the function of a venous valve. It is shown in the context of a transverse section. During systole corpuscles are shown flowing through the open valve. As the pressure reverses during diastole, the valve closes and back flow is blocked.

PhD Jack D Thatcher (West Virginia School of Osteopathic Medicine Structural Biology)

2009-11-20

54

Model-based predictive control of an Electro-Pneumatic exhaust valve for Internal Combustion engines  

Microsoft Academic Search

Variable valve actuation of internal combustion (IC) engines is capable of significantly improving their performance. Variable valve actuation can be divided into two main categories: variable valve timing with cam shaft(s) and camless valve actuation. For camless valve actuation, research has been centered in electro-magnetic, electro-hydraulic, and electro-pneumatic valve actuators. This research studies the control of the electro-pneumatic valve actuator.

Jia Ma; Guoming Zhu; Andrew Hartsig; Harold Schock

2008-01-01

55

Airborne asbestos exposures associated with gasket and packing replacement: A simulation study of flange and valve repair work and an assessment of exposure variables.  

PubMed

A simulation study was conducted to evaluate worker and area exposure to airborne asbestos associated with the replacement of asbestos-containing gaskets and packing materials from flanges and valves and assess the influence of several variables previously not investigated. Additionally, potential of take home exposures from clothing worn during the study was characterized. Our data showed that product type, ventilation type, gasket location, flange or bonnet size, number of flanges involved, surface characteristics, gasket surface adherence, and even activity type did not have a significant effect on worker exposures. Average worker asbestos exposures during flange gasket work (PCME=0.166f/cc, 12-59min) were similar to average worker asbestos exposures during valve overhaul work (PCME=0.165f/cc, 7-76min). Average 8-h TWA asbestos exposures were estimated to range from 0.010 to 0.062f/cc. Handling clothes worn during gasket and packing replacement activities demonstrated exposures that were 0.71% (0.0009f/cc 40-h TWA) of the airborne asbestos concentration experienced during the 5days of the study. Despite the many variables considered in this study, exposures during gasket and packing replacement occur within a relatively narrow range, are below current and historical occupational exposure limits for asbestos, and are consistent with previously published data. PMID:25445297

Madl, Amy K; Devlin, Kathryn D; Perez, Angela L; Hollins, Dana M; Cowan, Dallas M; Scott, Paul K; White, Katherine; Cheng, Thales J; Henshaw, John L

2015-02-01

56

The Effects of Basic Gymnastics Training Integrated with Physical Education Courses on Selected Motor Performance Variables  

ERIC Educational Resources Information Center

The purpose of this study is to determine the influence of gymnastics training integrated with physical education courses on selected motor performance variables in seven year old girls. Subjects were divided into two groups: (1) control group (N=15, X=7.56 plus or minus 0.46 year old); (2) gymnastics group (N=16, X=7.60 plus or minus 0.50 year…

Alpkaya, Ufuk

2013-01-01

57

Inter-individual variability in the adaptation of human muscle specific tension to progressive resistance training.  

PubMed

Considerable variation exists between people in the muscle response to resistance training, but there are numerous ways muscle might adapt to overload that might explain this variable response. Therefore, the aim of this study was to quantify the range of responses concerning the training-induced change in maximum voluntary contraction (MVC) knee joint torque, quadriceps femoris (QF) maximum muscle force (F), physiological cross-sectional area (PCSA) and specific tension (F/PCSA). It was hypothesized that the variable change in QF specific tension between individuals would be less than that of MVC. Fifty-three untrained young men performed progressive leg-extension training three times a week for 9 weeks. F was determined from MVC torque, voluntary muscle activation level, antagonist muscle co-activation and patellar tendon moment arm. QF specific tension was established by dividing F by QF PCSA, which was calculated from the ratio of QF muscle volume to muscle fascicle length. MVC torque increased by 26 ± 11% (P < 0.0001; range -1 to 52%), while F increased by 22 ± 11% (P < 0.0001; range -1 to 44%). PCSA increased by 6 ± 4% (P < 0.001; range -3 to 18%) and specific tension increased by 17 ± 11% (P < 0.0001; range -5 to 39%). In conclusion, training-induced changes in F and PCSA varied substantially between individuals, giving rise to greater inter-individual variability in the specific tension response compared to that of MVC. Furthermore, it appears that the change in specific tension is responsible for the variable change in MVC. PMID:20703498

Erskine, Robert M; Jones, David A; Williams, Alun G; Stewart, Claire E; Degens, Hans

2010-12-01

58

How musical training affects cognitive development: rhythm, reward and other modulating variables.  

PubMed

Musical training has recently gained additional interest in education as increasing neuroscientific research demonstrates its positive effects on brain development. Neuroimaging revealed plastic changes in the brains of adult musicians but it is still unclear to what extent they are the product of intensive music training rather than of other factors, such as preexisting biological markers of musicality. In this review, we synthesize a large body of studies demonstrating that benefits of musical training extend beyond the skills it directly aims to train and last well into adulthood. For example, children who undergo musical training have better verbal memory, second language pronunciation accuracy, reading ability and executive functions. Learning to play an instrument as a child may even predict academic performance and IQ in young adulthood. The degree of observed structural and functional adaptation in the brain correlates with intensity and duration of practice. Importantly, the effects on cognitive development depend on the timing of musical initiation due to sensitive periods during development, as well as on several other modulating variables. Notably, we point to motivation, reward and social context of musical education, which are important yet neglected factors affecting the long-term benefits of musical training. Further, we introduce the notion of rhythmic entrainment and suggest that it may represent a mechanism supporting learning and development of executive functions. It also hones temporal processing and orienting of attention in time that may underlie enhancements observed in reading and verbal memory. We conclude that musical training uniquely engenders near and far transfer effects, preparing a foundation for a range of skills, and thus fostering cognitive development. PMID:24672420

Miendlarzewska, Ewa A; Trost, Wiebke J

2013-01-01

59

Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring.  

PubMed

The measurement of heart rate variability (HRV) is often considered a convenient non-invasive assessment tool for monitoring individual adaptation to training. Decreases and increases in vagal-derived indices of HRV have been suggested to indicate negative and positive adaptations, respectively, to endurance training regimens. However, much of the research in this area has involved recreational and well-trained athletes, with the small number of studies conducted in elite athletes revealing equivocal outcomes. For example, in elite athletes, studies have revealed both increases and decreases in HRV to be associated with negative adaptation. Additionally, signs of positive adaptation, such as increases in cardiorespiratory fitness, have been observed with atypical concomitant decreases in HRV. As such, practical ways by which HRV can be used to monitor training status in elites are yet to be established. This article addresses the current literature that has assessed changes in HRV in response to training loads and the likely positive and negative adaptations shown. We reveal limitations with respect to how the measurement of HRV has been interpreted to assess positive and negative adaptation to endurance training regimens and subsequent physical performance. We offer solutions to some of the methodological issues associated with using HRV as a day-to-day monitoring tool. These include the use of appropriate averaging techniques, and the use of specific HRV indices to overcome the issue of HRV saturation in elite athletes (i.e., reductions in HRV despite decreases in resting heart rate). Finally, we provide examples in Olympic and World Champion athletes showing how these indices can be practically applied to assess training status and readiness to perform in the period leading up to a pinnacle event. The paper reveals how longitudinal HRV monitoring in elites is required to understand their unique individual HRV fingerprint. For the first time, we demonstrate how increases and decreases in HRV relate to changes in fitness and freshness, respectively, in elite athletes. PMID:23852425

Plews, Daniel J; Laursen, Paul B; Stanley, Jamie; Kilding, Andrew E; Buchheit, Martin

2013-09-01

60

Heart valve surgery - discharge  

MedlinePLUS

Aortic valve replacement - discharge; Aortic valvuloplasty - discharge; Aortic valve repair - discharge; Replacement - aortic valve - discharge; Repair - aortic valve - discharge; Ring annuloplasty - discharge; Percutaneous ...

61

Flow metering valve  

DOEpatents

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

Blaedel, Kenneth L. (Dublin, CA)

1985-01-01

62

Flow metering valve  

DOEpatents

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

Blaedel, K.L.

1983-11-03

63

Correlation of heart rate variability with cardiac functional and metabolic variables in cyclists with training induced left ventricular hypertrophy  

PubMed Central

OBJECTIVE—To examine the correlation between heart rate variability and left ventricular mass in cyclists with an athlete's heart.?METHODS—Left ventricular mass and diastolic function were determined at rest and myocardial high energy phosphates were quantified at rest and during atropine-dobutamine stress in 12 male cyclists and 10 control subjects, using magnetic resonance techniques. Ambulatory 24 hour ECG recordings were obtained, and time and frequency domain heart rate variability indices were computed.?RESULTS—In the cyclists, the mean of all RR intervals between normal beats (meanNN), the SD of the RR intervals, and their coefficient of variation were significantly greater than in control subjects (p < 0.01, p < 0.01, and p < 0.05, respectively). For cyclists and control subjects, only meanNN correlated with left ventricular mass (r = 0.48, p = 0.038). The heart rate variability indices that correlated with functional or metabolic variables were: meanNN v E/A peak (the ratio of peak early and peak atrial filling rate) (r = 0.48, p = 0.039); the root mean square of successive differences in RR intervals among successive normal beats v E/A area (ratio of peak early and peak atrial filling volume) (r = 0.48, p = 0.040); percentage of successive RR intervals differing by more than 50 ms v the phosphocreatine to ATP ratio at rest (r = 0.54, p = 0.017); and the SD of the average RR intervals during all five minute periods v the phosphocreatine to ATP ratio during stress (r = 0.60, p = 0.007).?CONCLUSIONS—Highly trained cyclists have increased heart rate variability indices, reflecting increased cardiac vagal control compared with control subjects. Left ventricular mass has no major influence on heart rate variability, but heart rate variability is significantly correlated with high energy phosphate metabolism and diastolic function.???Keywords: heart rate variability; left ventricular mass; hypertrophy; athlete's heart PMID:10336920

Pluim, B; Swenne, C; Zwinderman, A; Maan, A; van der Laarse, A; Doornbos, J; Van der Wall, E E

1999-01-01

64

Depressurization valve  

DOEpatents

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

Skoda, G.I.

1989-03-28

65

Variability of spike trains and the processing of temporal patterns of acoustic signals—problems, constraints, and solutions  

Microsoft Academic Search

Object recognition and classification by sensory pathways is rooted in spike trains provided by sensory neurons. Nervous systems had to evolve mechanisms to extract information about relevant object properties, and to separate these from spurious features. In this review, problems caused by spike train variability and counterstrategies are exemplified for the processing of acoustic signals in orthopteran insects. Due to

B. Ronacher; A. Franz; S. Wohlgemuth; R. M. Hennig

2004-01-01

66

49 CFR 236.508 - Interference with application of brakes by means of brake valve.  

Code of Federal Regulations, 2013 CFR

...AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Standards § 236.508 ...means of brake valve. The automatic train stop, train...

2013-10-01

67

49 CFR 236.508 - Interference with application of brakes by means of brake valve.  

Code of Federal Regulations, 2011 CFR

...AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Standards § 236.508 ...means of brake valve. The automatic train stop, train...

2011-10-01

68

Cylinder head variable swirl siamese type intake port structure including biasing means diverting mixture flow towards diverting means which bypasses straight intake passage control valve  

SciTech Connect

This patent describes a variable swirl siamese type intake port structure for an internal combustion engine cylinder head formed with a combustion chamber to which a spark plug having an ignition point is provided, comprising: a first generally straight intake passage which leads to a first intake port opening to the combustion chamber; a second generally helical intake passage which leads to a second intake port, also opening to the combustion chamber, formed with a helical end vortex portion; a control valve fitted in the first generally straight intake passage at an upstream portion thereof so as to control its flow resistance; a means, provided to the generally straight intake passage on the side thereof towards the generally helical intake passage.

Iwashita, Y.; Okumura, T.

1987-06-09

69

Improved Merge Valve  

NASA Technical Reports Server (NTRS)

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

George-Falvy, Dez

1992-01-01

70

Safety Valves  

Microsoft Academic Search

This problem can be solved in several different ways. In some cases, by means of a spring of specified strength that interacts with a drive mechanism (controlled by the pressure in the outlet cavity of the valve body) and the medium in contact with the working member (interacting with the valve seat) [1] and in other cases, by means of

V. M. Krasil'shchikov

2001-01-01

71

Yoga as steadiness training: effects on motor variability in young adults.  

PubMed

Exercise training programs can increase strength and improve submaximal force control, but the effects of yoga as an alternative form of steadiness training are not well described. The purpose was to explore the effect of a popular type of yoga (Bikram) on strength, steadiness, and balance. Young adults performed yoga training (n = 10, 29 +/- 6 years, 24 yoga sessions in 8 weeks) or served as controls (n = 11, 26 +/- 7 years). Yoga sessions consisted of 1.5 hours of supervised, standardized postures. Measures before and after training included maximum voluntary contraction (MVC) force of the elbow flexors (EF) and knee extensors (KE), steadiness of isometric EF and KE contractions, steadiness of concentric (CON) and eccentric (ECC) KE contractions, and timed balance. The standard deviation (SD) and coefficient of variation (CV, SD/mean force) of isometric force and the SD of acceleration during CON and ECC contractions were measured. After yoga training, MVC force increased 14% for KE (479 +/- 175 to 544 +/- 187 N, p < 0.05) and was unchanged for the EF muscles (219 +/- 85 to 230 +/- 72 N, p > 0.05). The CV of force was unchanged for EF (1.68 to 1.73%, p > 0.05) but was reduced in the KE muscles similarly for yoga and control groups (2.04 to 1.55%, p < 0.05). The variability of CON and ECC contractions was unchanged. For the yoga group, improvement in KE steadiness was correlated with pretraining steadiness (r = -0.62 to -0.84, p < 0.05); subjects with the greatest KE force fluctuations before training experienced the greatest reductions with training. Percent change in balance time for individual yoga subjects averaged +228% (19.5 +/- 14 to 34.3 +/- 18 seconds, p < 0.05), with no change in controls. For young adults, a short-term yoga program of this type can improve balance substantially, produce modest improvements in leg strength, and improve leg muscle control for less-steady subjects. PMID:18714217

Hart, Cady E F; Tracy, Brian L

2008-09-01

72

Variability of island-induced ocean vortex trains, in the Kuroshio region southeast of Taiwan Island  

NASA Astrophysics Data System (ADS)

This study examines the horizontal scale and spatial characteristics of island-induced ocean vortex trains (IOVTs) in the Kuroshio region southeast of Taiwan Island using European remote sensing satellite ERS-1 SAR imagery. US Aqua satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data are used to analyze the sea surface temperature (SST) features of the study area. Seasonal composites of SST images show that the IOVTs are current-induced vortexes rather than wind-induced ones. Furthermore, using the HYbrid Coordinate Ocean Model/Navy Coupled Ocean Data Assimilation (HYCOM/NCODA) system that generated current and sea surface height anomaly data, the temporal and spatial variability of the Green Island IOVTs is analyzed. The variability of IOVTs within this region shows a distinct seasonality. This seasonal variability of IOVTs is closely associated with the shoreward shift of Kuroshio mainstream driven by the winter northeasterly monsoon. This scenario is verified by vector empirical orthogonal function analysis focused on the weak IOVT period in 2012. In addition to meandering of the Kuroshio, westward-propagating mesoscale eddies and the arrival of typhoons play an important role in modifying the variability of IOVTs at intraseasonal timescale.

Zheng, Zhe-Wen; Zheng, Quanan

2014-06-01

73

Inter-individual variability in adaptation of the leg muscles following a standardised endurance training programme in young women.  

PubMed

There is considerable inter-individual variability in adaptations to endurance training. We hypothesised that those individuals with a low local leg-muscle peak aerobic capacity (VO2peak) relative to their whole-body maximal aerobic capacity (VO2max) would experience greater muscle training adaptations compared to those with a relatively high VO2peak. 53 untrained young women completed one-leg cycling to measure VO2peak and two-leg cycling to measure VO2max. The one-leg VO2peak was expressed as a ratio of the two-leg VO2max (Ratio(1:2)). Magnetic resonance imaging was used to indicate quadriceps muscle volume. Measurements were taken before and after completion of 6 weeks of supervised endurance training. There was large inter-individual variability in the pre-training Ratio(1:2) and large variability in the magnitude of training adaptations. The pre-training Ratio(1:2) was not related to training-induced changes in VO2max (P = 0.441) but was inversely correlated with changes in one-leg VO2peak and muscle volume (P < 0.05). No relationship was found between the training-induced changes in two-leg VO2max and one-leg VO2peak (r = 0.21; P = 0.129). It is concluded that the local leg-muscle aerobic capacity and Ratio(1:2) vary from person to person and this influences the extent of muscle adaptations following standardised endurance training. These results help to explain why muscle adaptations vary between people and suggest that setting the training stimulus at a fixed percentage of VO2max might not be a good way to standardise the training stimulus to the leg muscles of different people. PMID:20369366

McPhee, Jamie S; Williams, Alun G; Degens, Hans; Jones, David A

2010-08-01

74

Depressurization valve  

DOEpatents

A depressurization valve for use in relieving completely the pressure in a simplified boiling water reactor is disclosed. The normally closed and sealed valve is provided with a valve body defining a conduit from an outlet of a manifold from the reactor through a valve seat. A closing valve disk is configured for fitting to the valve seat to normally close the valve. The seat below the disk is provided with a radially extending annulus extending a short distance into the aperture defined by the seat. The disk is correspondingly provided with a longitudinally extending annulus that extends downwardly through the aperture defined by the seat towards the high pressure side of the valve body. A ring shaped membrane is endlessly welded to the seat annulus and to the disk annulus. The membrane is conformed over the confronted surface of the seat and disk in a C-sectioned configuration to seal the depressurization valve against the possibility of weeping. The disk is held to the closed position by an elongate stem extending away from the high pressure side of the valve body. The stem has a flange configured integrally to the stem for bias by two springs. The first spring acts from a portion of the housing overlying the disk on the stem flange adjacent the disk. This spring urges the stem and attached disk away from the seat and thus will cause the valve to open at any pressure. A second spring--preferably of the Belleville variety--acts on a latch plate surrounding and freely moving relative to the end of the stem. This second spring overcomes the bias of the first spring and any pressure acting upon the disk. This Belleville spring maintains through its spring force the valve in the closed position. At the same time, the latch plate with its freedom of movement relative to the stem allows the stem to thermally expand during valve temperature excursion. The latch plate in surrounding the stem is limited in its outward movement by a boss attached to the stem at the end of the stem remote from the disk. The latch plate is held normally closed by three radial latches spaced at 120.degree. around the periphery of the plate.

Skoda, George I. (Santa Clara, CA)

1989-01-01

75

Determining variables of plyometric training for improving vertical jump height performance: a meta-analysis.  

PubMed

Plyometric training improves vertical jump height (VJH). However, the effectiveness of plyometric training depends on various factors. A meta-analysis of 56 studies with a total of 225 effect sizes (ESs) was carried out to analyze the role of various factors on the effects of plyometrics on VJH performance. The inclusion criteria for the analysis were a) studies using plyometric programs for lower-limb muscles, b) studies employing true experimental designs and valid and reliable measurements, and c) studies including enough data to calculate ESs. Subjects with more experience in sport obtained greater enhancements in VJH performance (p < 0.01). Subjects in either good or bad physical condition benefit equally from plyometric work (p < 0.05), although men tend to obtain better power results than women after plyometric training (p < 0.05). With relation to the variables of performance, training volumes of more than 10 weeks and more than 20 sessions, using high-intensity programs (with more than 50 jumps per session), were the strategies that seemed to maximize the probability of obtaining significantly greater improvements in performance (p < 0.05). To optimize jumping enhancement, the combination of different types of plyometrics (squat jump + countermovement jump + drop jump) is recommended rather than using only 1 form (p < 0.05). However, no extra benefits were found to be gained from doing plyometrics with added weight. The responses identified in this analysis are essential and should be considered by strength and conditioning professionals with regard to the most appropriate dose-response trends for optimizing plyometric-induced gains. PMID:19197203

de Villarreal, Eduardo Saéz-Saez; Kellis, Eleftherios; Kraemer, William J; Izquierdo, Mikel

2009-03-01

76

Nuclear radiation actuated valve  

DOEpatents

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

Christiansen, David W. (Kennewick, WA); Schively, Dixon P. (Richland, WA)

1985-01-01

77

Atrioventricular Valves  

NSDL National Science Digital Library

This FlashTM animation depicts development of the atrioventricular canal into the bicuspid and tricuspid valves. For context it begins with a ventral view of the two chambered heart. Clicking causes the surface to open revealing a cross section through the primitive ventricle. Next the animation zooms in to show the atrioventricular canal developing endocardial cushions and separating into the right and left atrioventricular orifices. From there the perspective shifts to show a cross section through the left orifice and depicts a stylized view of the development of an AV valve. The animation then shifts back to show a ventral view of the bicuspid and tricuspid valves, and ends with corpuscles pouring through the valves as they open and close.

PhD Jack D Thatcher (West Virginia School of Osteopathic Medicine Structural Biology)

2009-11-20

78

Valve Disease  

MedlinePLUS

... your heart rate and lower your blood pressure. Calcium channel blockers affect the contractions of muscle tissue in your ... pressure and reducing the workload on your heart, calcium channel blockers may put off the need for heart valve ...

79

PERFORMANCE OF AN AERIAL VARIABLE-RATE APPLICATION SYSTEM WITH A HYDRAULICALLY POWERED CHEMICAL PUMP AND SPRAY VALVE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The performance was evaluated for a variable-rate system that consisted of a SATLOC M3 with AirTrac software with WAAS corrected DGPS (5 Hz position update) and an AutoCal II automatic flow controller. This system was installed on an Air Tractor 402B equipped with an auxiliary hydraulic package tha...

80

Analysis of Complex Valve and Feed Systems  

NASA Technical Reports Server (NTRS)

A numerical framework for analysis of complex valve systems supports testing of propulsive systems by simulating key valve and control system components in the test loop. In particular, it is designed to enhance the analysis capability in terms of identifying system transients and quantifying the valve response to these transients. This system has analysis capability for simulating valve motion in complex systems operating in diverse flow regimes ranging from compressible gases to cryogenic liquids. A key feature is the hybrid, unstructured framework with sub-models for grid movement and phase change including cryogenic cavitations. The multi-element unstructured framework offers improved predictions of valve performance characteristics under steady conditions for structurally complex valves such as pressure regulator valve. Unsteady simulations of valve motion using this computational approach have been carried out for various valves in operation at Stennis Space Center such as the split-body valve and the 10-in. (approx.25.4-cm) LOX (liquid oxygen) valve and the 4-in. (approx.10 cm) Y-pattern valve (liquid nitrogen). Such simulations make use of variable grid topologies, thereby permitting solution accuracy and resolving important flow physics in the seat region of the moving valve. An advantage to this software includes possible reduction in testing costs incurred due to disruptions relating to unexpected flow transients or functioning of valve/flow control systems. Prediction of the flow anomalies leading to system vibrations, flow resonance, and valve stall can help in valve scheduling and significantly reduce the need for activation tests. This framework has been evaluated for its ability to predict performance metrics like flow coefficient for cavitating venturis and valve coefficient curves, and could be a valuable tool in predicting and understanding anomalous behavior of system components at rocket propulsion testing and design sites.

Ahuja, Vineet; Hosangadi, Ashvin; Shipman, Jeremy; Cavallo, Peter; Dash, Sanford

2007-01-01

81

Extremum Seeking Control for Soft Landing of an Electromechanical Valve Actuator  

E-print Network

Extremum Seeking Control for Soft Landing of an Electromechanical Valve Actuator Katherine S Abstract Many electromagnetic actuators suffer from high velocity impacts. One such actuator is the electromechanical valve actuator, recently receiving attention for enabling variable valve timing in internal

Stefanopoulou, Anna

82

Dissociation of heart rate variability and heart rate recovery in well-trained athletes.  

PubMed

The purpose of this investigation was to examine the relationships between aerobic fitness, volume of physical activity (PA), heart rate variability (HRV), and heart rate recovery (HRR) in a group of well-trained endurance athletes. Nineteen endurance athletes participated in this study and had aerobic capacities that placed them above the 99th percentile based on normative values (VO(2max): 67.1 ± 2 ml kg(-1) min(-1)). HRV was obtained via an EKG collected during supine rest and reported as high-frequency (HF), low-frequency (LF), and total power (TP). Natural log (ln) transformation was applied when variables violated assumptions of normality. HRR recovery was reported as the reduction in heart rate from peak exercise to the heart rate 1 min after cessation of exercise and PA was estimated from a questionnaire. HRR was significantly correlated with PA and VO(2max) (r = 0.67, P = 0.003 and 0.51, P = 0.039, respectively), but not with any index of HRV. Age was significantly correlated with lnHF (r = -0.49, P = 0.033), lnLF/lnHF (r = 0.48, P = 0.037), and normalized units (NU) of LF (r = 0.47, P = 0.042) and HF (r = -0.47, P = 0.042). Stepwise regression revealed that the strongest predictor of HRR was PA (R (2) = 0.45) and that VO(2max) did not add significant predictive value to the model. The relationship between HRV and age is evident in well-trained endurance athletes, whereas the relationship between HRV and PA/aerobic fitness is not. The maintained relationship between HRR and PA/aerobic fitness suggests that HRR may be a better marker of fitness-related differences in autonomic control in this population. PMID:22124525

Lee, C Matthew; Mendoza, Albert

2012-07-01

83

Cooling performance of a variable speed CO 2 cycle with an electronic expansion valve and internal heat exchanger  

Microsoft Academic Search

The cooling performance of a CO2 cycle must be improved to develop a competitive air-conditioning system with the conventional air-conditioners using HFCs. In this study, the cooling performance of a variable speed CO2 cycle was measured and analyzed by varying the refrigerant charge amount, compressor frequency, EEV opening, and length of an internal heat exchanger (IHX). The basic CO2 system

Honghyun Cho; Changgi Ryu; Yongchan Kim

2007-01-01

84

Titanium in Engine Valve Systems  

NASA Astrophysics Data System (ADS)

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

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

1987-03-01

85

Design and Experimental Implementation of an Electromagnetic Engine Valve Drive  

E-print Network

In conventional internal combustion engines, engine valve displacements are fixed relative to crankshaft position. If these valves were actuated as a variable function of crankshaft angle, significant improvements in fuel ...

Parlikar, T.A.

86

Training  

ERIC Educational Resources Information Center

Discusses factors leading to the formation of the British Gas Corporation (BGC) in 1973 and how the main functions of BGC (sales and purchasing, engineering, service, and finance and personnel) plus management training and training technology across these functions blend together to provide an effective service throughout BGC. (SH)

Bostock, Geoffrey

1977-01-01

87

Generation of Picosecond Electron-Bunch Trains with Variable Spacing Using a Multi-Pulse Photocathode Laser  

SciTech Connect

We demonstrate the generation of a train of electron bunches with variable spacing at the Argonne Wakefield Accelerator. The photocathode ultraviolet laser pulse consists of a train of four pulses produced via polarization splitting using two alpha-BBO crystals. The photoemitted electron bunches are then manipulated in a horizontally-bending dogleg with variable longitudinal dispersion. A downstream vertically-deflecting cavity is then used to diagnose the temporal profile of the electron beam. The generation of a train composed of four bunches with tunable spacing is demonstrated. Such a train of bunch could have application to, e.g., the resonant excitation of wakefield in dielectric-lined structures. We have presented preliminary measurements on a simple technique to generate a train of electron bunches with variable separation. In the initial experiment appreciable density modulation down to wavelengths of {approx}1.8 mm (corresponding to a temporal separation of {approx}6 ps) were achieved for a total charge of 0.5 nC. Finding ways to reach smaller separations is being explored with the help of numerical simulations and will be presented elsewhere.

Conde, M.; Gai, W.; /Argonne; Jing, C.; /Euclid TechLabs /Argonne; Konecny, R.; Liu, W.; /Argonne; Mihalcea, D.; /Northern Illinois U.; Piot, P.; /Northern Illinois U. /Fermilab; Power, J.G.; /Argonne; Rihaoui, M.; /Northern Illinois U.; Yusof, Z.; /Argonne

2012-07-08

88

Piezoelectric valve  

DOEpatents

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.

Petrenko, Serhiy Fedorovich

2013-01-15

89

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

Code of Federal Regulations, 2011 CFR

...false Valve locks, valves, and valve magnets. 236.383 Section 236.383 Transportation...383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off...every three months, and valves and valve magnets shall be tested at least once every...

2011-10-01

90

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

Code of Federal Regulations, 2013 CFR

...false Valve locks, valves, and valve magnets. 236.383 Section 236.383 Transportation...383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off...every three months, and valves and valve magnets shall be tested at least once every...

2013-10-01

91

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

Code of Federal Regulations, 2010 CFR

...false Valve locks, valves, and valve magnets. 236.383 Section 236.383 Transportation...383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off...every three months, and valves and valve magnets shall be tested at least once every...

2010-10-01

92

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

Code of Federal Regulations, 2012 CFR

...false Valve locks, valves, and valve magnets. 236.383 Section 236.383 Transportation...383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off...every three months, and valves and valve magnets shall be tested at least once every...

2012-10-01

93

Year-to-year variability in haemoglobin mass response to two altitude training camps  

PubMed Central

Aim To quantify the year-to-year variability of altitude-induced changes in haemoglobin mass (Hbmass) in elite team-sport athletes. Methods 12 Australian-Footballers completed a 19-day (ALT1) and 18-day (ALT2) moderate altitude (?2100?m), training camp separated by 12?months. An additional 20 participants completed only one of the two training camps (ALT1 additional n=9, ALT2 additional n=11). Total Hbmass was assessed using carbon monoxide rebreathing before (PRE), after (POST1) and 4?weeks after each camp. The typical error of Hbmass for the pooled data of all 32 participants was 2.6%. A contemporary statistics analysis was used with the smallest worthwhile change set to 2% for Hbmass. Results POST1 Hbmass was very likely increased in ALT1 (3.6±1.6%, n=19; mean±?90 CL) as well as ALT2 (4.4±1.3%, n=23) with an individual responsiveness of 1.3% and 2.2%, respectively. There was a small correlation between ALT1 and ALT2 (R=0.21, p=0.59) for a change in Hbmass, but a moderately inverse relationship between the change in Hbmass and initial relative Hbmass (g/kg (R=?0.51, p=0.04)). Conclusions Two preseason moderate altitude camps 1?year apart yielded a similar (4%) mean increase in Hbmass of elite footballers, with an individual responsiveness of approximately half the group mean effect, indicating that most players gained benefit. Nevertheless, the same individuals generally did not change their Hbmass consistently from year to year. Thus, a ‘responder’ or ‘non-responder’ to altitude for Hbmass does not appear to be a fixed trait. PMID:24282208

McLean, Blake D; Buttifant, David; Gore, Christopher J; White, Kevin; Kemp, Justin

2013-01-01

94

Effects of Exercise Training on Heart Rate Variability in Chagas Heart Disease  

PubMed Central

Background: Heart rate variability (HRV) is a marker of autonomic dysfunction severity. The effects of physical training on HRV indexes in Chagas heart disease (CHD) are not well established. Objective: To evaluate the changes in HRV indexes in response to physical training in CHD. Methods: Patients with CHD and left ventricular (LV) dysfunction, physically inactive, were randomized either to the intervention (IG, N = 18) or control group (CG, N = 19). The IG participated in a 12-week exercise program consisting of 3 sessions/week. Results: Mean age was 49.5 ± 8 years, 59% males, mean LVEF was 36.3 ± 7.8%. Baseline HRV indexes were similar between groups. From baseline to follow-up, total power (TP): 1653 (IQ 625 - 3418) to 2794 (1617 - 4452) ms, p = 0.02) and very low frequency power: 586 (290 - 1565) to 815 (610 - 1425) ms, p = 0.047) increased in the IG, but not in the CG. The delta (post - pre) HRV indexes were similar: SDNN 11.5 ± 30.0 vs. 3.7 ± 25.1 ms. p = 0.10; rMSSD 2 (6 - 17) vs. 1 (21 - 9) ms. p = 0.43; TP 943 (731 - 3130) vs. 1780 (921 - 2743) Hz. p = 0.46; low frequency power (LFP) 1.0 (150 - 197) vs. 60 (111 - 146) Hz. p = 0.85; except for high frequency power, which tended to increase in the IG: 42 (133 - 92) vs. 79 (61 - 328) Hz. p = 0.08). Conclusion: In the studied population, the variation of HRV indexes was similar between the active and inactive groups. Clinical improvement with physical activity seems to be independent from autonomic dysfunction markers in CHD. PMID:25098373

Nascimento, Bruno Ramos; Lima, Márcia Maria Oliveira; Nunes, Maria do Carmo Pereira; de Alencar, Maria Clara Noman; Costa, Henrique Silveira; Pinto Filho, Marcelo Martins; Cota, Vitor Emanuel Serafim; Rocha, Manoel Otávio da Costa; Ribeiro, Antonio Luiz Pinho

2014-01-01

95

Application of alpha/theta neurofeedback and heart rate variability training to young contemporary dancers: state anxiety and creativity.  

PubMed

As one in a series on the impact of EEG-neurofeedback in the performing arts, we set out to replicate a previous dance study in which alpha/theta (A/T) neurofeedback and heart rate variability (HRV) biofeedback enhanced performance in competitive ballroom dancers compared with controls. First year contemporary dance conservatoire students were randomised to the same two psychophysiological interventions or a choreology instruction comparison group or a no-training control group. While there was demonstrable neurofeedback learning, there was no impact of the three interventions on dance performance as assessed by four experts. However, HRV training reduced anxiety and the reduction correlated with improved technique and artistry in performance; the anxiety scale items focussed on autonomic functions, especially cardiovascular activity. In line with the putative impact of hypnogogic training on creativity A/T training increased cognitive creativity with the test of unusual uses, but not insight problems. Methodological and theoretical implications are considered. PMID:23684733

Gruzelier, J H; Thompson, T; Redding, E; Brandt, R; Steffert, T

2014-07-01

96

Miniature piezo electric vacuum inlet valve  

DOEpatents

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability is disclosed. The low power (<1.6 watts), high pulse rate (<2 milliseconds), variable flow inlet valve is utilized for mass spectroscopic applications or other applications where pulsed or continuous flow conditions are needed. The inlet valve also has a very minimal dead volume of less than 0.01 std/cc. The valve can utilize, for example, a 12 Vdc input/750 Vdc, 3 mA output power supply compared to conventional piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three. 6 figs.

Keville, R.F.; Dietrich, D.D.

1998-03-24

97

Miniature piezo electric vacuum inlet valve  

DOEpatents

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability. The low power (<1.6 watts), high pulse rate (<2 milliseconds), variable flow inlet valve is utilized for mass spectroscopic applications or other applications where pulsed or continuous flow conditions are needed. The inlet valve also has a very minimal dead volume of less than 0.01 std/cc. The valve can utilize, for example, a 12 Vdc input/750 Vdc, 3 mA output power supply compared to conventional piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three.

Keville, Robert F. (Valley Springs, CA); Dietrich, Daniel D. (Livermore, CA)

1998-03-24

98

Oxygen injector ventilation in adults and children: use of a variable pressure driving gas valve and a right angled connector.  

PubMed

An oxygen injector system (Harwill Medical, South Africa) was tested for ventilating intubated patients. There were 21 adults and 25 children. The system incorporates a variable pressure reducing value and a right-angled end connection with a 14 gauge oxygen exit nozzle and a 12 mm side port to atmosphere. Intravenous propofol was used to maintain anaesthesia, while the patients underwent alternate 10-minute periods of ventilation with the oxygen injector or an Ohmedia 7000 ventilator. Tidal volumes (ml/kg) achieved by mechanical ventilation were 8.06 +/- 1.89 in adults and 7.28 +/- 2.01 in children, compared with 5.79 +/- 2.13 and 4.57 +/- 1.58 respectively, with the oxygen injector (P > 0.05). Peak airway pressures (cmH2O) on mechanical ventilation were 18.61 +/- 3.06 and 20.21 +/- 2.89 in adults and children. The corresponding pressures with the oxygen injector were 19.42 +/- 3.97 and 18.49 +/- 3.27 (P > 0.05). Cardiovascular parameters were unchanged. A side port adaptation provided a suction capability for water at a rate of 9.16 ml/s. We conclude that this system is an effective universal ventilator suitable for short-term ventilation and suction of patients. PMID:10456137

Payne, K A; Van Rensburg, J

1998-01-01

99

Plasma valve  

DOEpatents

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

Hershcovitch, Ady (Mount Sinai, NY); Sharma, Sushil (Hinsdale, IL); Noonan, John (Naperville, IL); Rotela, Elbio (Clarendon Hills, IL); Khounsary, Ali (Hinsdale, IL)

2003-01-01

100

Detraining Produces Minimal Changes in Physical Performance and Hormonal Variables in Recreationally Strength-Trained Men  

Microsoft Academic Search

The object of this study was to examine changes in muscular strength, power, and resting hormonal concentrations during 6 weeks of detraining (DTR) in recreationally strength- trained men. Each subject was randomly assigned to either a DTR (n 5 9) or resistance training (RT; n 5 7) group after being matched for strength, body size, and training experi- ence. Muscular

WILLIAM J. KRAEMER; L. PERRY KOZIRIS; NICHOLAS A. RATAMESS; KEIJO HÄKKINEN; N. TRAVIS TRIPLETT-McBRIDE; ANDREW C. FRY; SCOTT E. GORDON; JEFF S. VOLEK; DUNCAN N. FRENCH; MARTYN R. RUBIN; ANA L. GÓMEZ; MATTHEW J. SHARMAN; J. MICHAEL LYNCH; MIKEL IZQUIERDO; ROBERT U. NEWTON; STEVEN J. FLECK

2002-01-01

101

Late results of valve replacement with the Björk-Shiley valve (1973 to 1982)  

PubMed

Cardiac valve replacement with use of only the Björk-Shiley prosthesis was performed in 1253 patients between January 1973 and December 1982. There were 828 patients having aortic valve replacement, 280 patients having mitral valve replacement, and 145 patients having double valve replacement with aortic and mitral valve prostheses. Patient outcome was stratified according to multiple variables, including valve position and valve model (spherical versus convexo-concave discs). No valve failure due to strut fracture was identified in 26 high-risk patients (mitral valve replacement with greater than or equal to 29 mm implanted in patients less than or equal to 50 years of age) followed up for a mean of 10 years postoperatively. Fifteen patients had late thrombosis of their Björk-Shiley prosthesis (0.28 per 100 patient-years), but there was no significant difference in risk of valve thrombosis comparing the spherical and convexo-concave discs (0.27 per 100 patient-years versus 0.27 per 100 patient-years). One hundred two patients had 128 thromboembolic episodes; rates of thromboembolism after aortic valve replacement, mitral valve replacement, and double valve replacement were 2.1, 4.3, and 4.6 per 100 patient-years, respectively. Percentages of patients free from thromboemboli after aortic valve replacement, mitral valve replacement, and double valve replacement were 93% +/- 1%, 86% +/- 2%, and 89% +/- 3% at 5 years postoperatively and 87% +/- 2%, 79% +/- 5%, and 77% +/- 8% 10 years postoperatively. There was no significant difference in the rates of thromboemboli for spherical and convexo-concave discs for all patients and for each of the subgroups. Ten-year actuarial survival estimates for patients dismissed alive from the hospital after aortic valve replacement, mitral valve replacement, and double valve replacement with the Björk-Shiley valve were 65% +/- 4%, 63% +/- 5%, and 55% +/- 8%, respectively. Overall event-free survival (freedom from death, thromboembolism, anticoagulant-related bleeding, endocarditis, and reoperation) was similar for the three patient groups. Performance of the Björk-Shiley valve as judged by late patient follow-up is similar to other mechanical valves, and modifications in disc design do not appear to have reduced the threat of late valve thrombosis and thromboemboli. Evidence does not support elective explantation of this prosthesis. PMID:8429659

Orszulak, T A; Schaff, H V; DeSmet, J M; Danielson, G K; Pluth, J R; Puga, F J

1993-02-01

102

High speed exhaust gas recirculation valve  

DOEpatents

In order to minimize pollutants such as Nox, internal combustion engines typically include an exhaust gas recirculation (EGR) valve that can be used to redirect a portion of exhaust gases to an intake conduit, such as an intake manifold, so that the redirected exhaust gases will be recycled. It is desirable to have an EGR valve with fast-acting capabilities, and it is also desirable to have the EGR valve take up as little space as possible. An exhaust gas recirculation valve is provided that includes an exhaust passage tube, a valve element pivotally mounted within the exhaust passage tube, a linear actuator; and a gear train. The gear train includes a rack gear operatively connected to the linear actuator, and at least one rotatable gear meshing with the rack gear and operatively connected to the valve element to cause rotation of the valve element upon actuation of the linear actuator. The apparatus provides a highly compact package having a high-speed valve actuation capability.

Fensom, Rod (Peterborough, GB); Kidder, David J. (Peterborough, GB)

2005-01-18

103

Analysis and Simulation of Mechanical Trains Driven by Variable Frequency Drive Systems  

E-print Network

Mechanics Model for VFD Driven Motor-Gearbox-Compressor Train with FOC; Assumptions: Ideal DC Bus Voltage and Ideal Inverter Power Switches : : : : : : : : : : : : : : 93 73 Motor-Gearbox-Compressor Train with FOC; Rotor Speed { Motor Target Speed 1750 rpm...; Assumptions: Ideal DC Bus Voltage and Ideal Inverter Power Switches : : : : : : : : : : : : : : : : : : : : 96 74 Motor-Gearbox-Compressor Train with FOC; Relative Angu- lar Displacement between Motor and Gear#1 { Motor Target Speed 1750 rpm; Assumptions...

Han, Xu

2012-02-14

104

An experimental study of flow through a rotating disc valve  

Microsoft Academic Search

It is known that the mass flow rate through poppet valves of 4-stroke cycle engines and through piston valves of 2-stroke cycle engines decreases with increase in engine speed. A disc-type rotary valve is used to experimentally analyze the decrease in flow rate at high rotational speeds and to determine what variables, other than rotational speed, give rise to the

J. Iwamoto; B. E. Deckker

1984-01-01

105

Conical Seat Shut-Off Valve  

NASA Technical Reports Server (NTRS)

A moveable valve for controlling flow of a pressurized working fluid was designed. This valve consists of a hollow, moveable floating piston pressed against a stationary solid seat, and can use the working fluid to seal the valve. This open/closed, novel valve is able to use metal-to-metal seats, without requiring seat sliding action; therefore there are no associated damaging effects. During use, existing standard high-pressure ball valve seats tend to become damaged during rotation of the ball. Additionally, forces acting on the ball and stem create large amounts of friction. The combination of these effects can lead to system failure. In an attempt to reduce damaging effects and seat failures, soft seats in the ball valve have been eliminated; however, the sliding action of the ball across the highly loaded seat still tends to scratch the seat, causing failure. Also, in order to operate, ball valves require the use of large actuators. Positioning the metal-to-metal seats requires more loading, which tends to increase the size of the required actuator, and can also lead to other failures in other areas such as the stem and bearing mechanisms, thus increasing cost and maintenance. This novel non-sliding seat surface valve allows metal-to-metal seats without the damaging effects that can lead to failure, and enables large seating forces without damaging the valve. Additionally, this valve design, even when used with large, high-pressure applications, does not require large conventional valve actuators and the valve stem itself is eliminated. Actuation is achieved with the use of a small, simple solenoid valve. This design also eliminates the need for many seals used with existing ball valve and globe valve designs, which commonly cause failure, too. This, coupled with the elimination of the valve stem and conventional valve actuator, improves valve reliability and seat life. Other mechanical liftoff seats have been designed; however, they have only resulted in 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.

Farner, Bruce

2013-01-01

106

Magnetically operated check valve  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

107

Mechanical heart valves: Changes in patient survival and valve failure rates  

Microsoft Academic Search

The effect of patient related variables and mechanical heart valve substitutes on survival and valve failure rates was studied\\u000a in 2,778 patients operated between 1966 and 1986. Of these 48.2% were operated without cardioplegic protection (phase I) and\\u000a 51.8% thereafter (phase II). Mitral vlave replacement (MVR) was performed in 1,257 patients (phase I: 51.58%, phase II: 48.42%);\\u000a aortic valve replacement

T. K. Kaul; J. L. Mercer; D. R. Ramsdale

1992-01-01

108

Train  

NSDL National Science Digital Library

This web page provides instructions for a game that develops number sense, basic addition and subtraction skills, and strategic thinking. Beginning with 10 Cuisenaire rods, one of each length from 1 (white) and 10 (orange), two players take turns adding one rod at a time to a train until it reaches a previously agreed-on length between 11 and 55. The player who puts down the last rod to complete the goal length is the winner. The game can be played with real rods, with the Flash applet provided, or with numbers on paper.

2005-10-01

109

Perceval Sutureless valve - are Sutureless valves here?  

PubMed

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

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

2014-11-13

110

Aortic valve replacement: Is valve size important?  

Microsoft Academic Search

Objective: We sought to determine whether aortic prosthesis size adversely influences survival after aortic valve replacement. Methods: A total of 892 adults receiving a mechanical (n = 346), pericardial (n = 463), or allograft (n = 83) valve for aortic stenosis were observed for up to 20 years (mean, 5.0 ± 3.9 years) after primary isolated aortic valve replacement. We

Benjamin Medalion; Eugene H. Blackstone; Bruce W. Lytle; Jennifer White; John H. Arnold; Delos M. Cosgrove

2000-01-01

111

Effects of increased training load on vagal-related indexes of heart rate variability: a novel sleep approach.  

PubMed

There is little doubt that moderate training improves cardiac vagal activity and thus has a cardioprotective effect against lethal arrhythmias. Our purpose was to learn whether a higher training load would further increase this beneficial effect. Cardiac autonomic control was inferred from heart rate variability (HRV) and analyzed in three groups of young subjects (24.5 +/- 3.0 yr) with different training states in a period free of stressful stimuli or overload. HRV was analyzed in 5-min segments during slow-wave sleep (SWS, a parasympathetic state that offers high electrocardiographic stationarity) and compared with data collected during quiet waking periods in the morning. Sleep parameters, fatigue, and stress levels checked by questionnaire were identical for all three groups with no signs of overtraining in the highly trained (HT) participants. During SWS, a significant (P <0.05) increase in absolute and normalized vagal-related HRV indexes was observed in moderately trained (MT) individuals compared with sedentary (Sed) subjects; this increase did not persist in HT athletes. During waking periods, most of the absolute HRV indexes indistinctly increased in MT individuals compared with controls (P < 0.05) but did not increase in HT athletes. Normalized spectral HRV indexes did not change significantly among the three groups. Heart rate was similar for MT and Sed subjects but was significantly (P <0.05) lower in HT athletes under both recording conditions. These results indicate that SWS discriminates the state of sympathovagal balance better than waking periods. A moderate training load is sufficient to increase vagal-related HRV indexes. However, in HT individuals, despite lower heart rate, vagal-related HRV indexes return to Sed values even in the absence of competition, fatigue, or overload. PMID:15308479

Buchheit, M; Simon, C; Piquard, F; Ehrhart, J; Brandenberger, G

2004-12-01

112

Low-noise nozzle valve  

NASA Technical Reports Server (NTRS)

A low noise, variable discharage area, valve is constructed having opposed recesses within which a pair of gates are slidably disposed. Each of the gates is provided with upstream edges having a radius thereon, the radius enabling smooth, accelerated, low noise flow therebetween. The gates are further provided with tracks along each side, which in turn slide along splines set in the side walls of the valve. A threaded rod which rotates in a threaded insert in a rear wall of each of the gates, serves to move the gates within their respective recesses.

Gwin, Hal S. (inventor); Aaron, James (inventor)

1990-01-01

113

Variability in Step Training Enhances Locomotor Recovery After a Spinal Cord Injury  

PubMed Central

Performance of a motor task is improved by practicing a specific task with added “challenges” to a training regimen. We tested the hypothesis that in the absence of brain control the performance of a motor task is enhanced by training using specific variations of that task. We utilized modifications of step performance training to improve the ability of spinal rats to forward step. After a complete thoracic spinal cord transection, 20 adult rats were divided randomly to bipedally step on a treadmill in the forward, sideward, or backward direction for 28 sessions (20 min, 5d/week) and subsequently tested for their ability to step in the forward direction. Although the animals from all trained groups showed improvement, the rats in the sideward trained and backward trained groups had greater step consistency and coordination along with higher peak amplitudes and total integrated activity of the rectified electromyography signals from selected hindlimb muscles per step during forward stepping than the rats in the forward trained group. Our results demonstrate that by retaining the fundamental features of a motor task (bipedal stepping) the ability to perform that motor task can be enhanced by the addition of specific contextual variations to the task (direction of stepping). Our data suggest that the forward stepping neuronal locomotor networks are partially complemented by synchronous activation of interneuronal/motoneuronal populations that are also a part of the sideward or backward stepping locomotor networks. Accordingly, the overlap and interaction of neuronal elements may play a critical role in positive task transference. PMID:22591277

Shah, Prithvi; Gerasimenko, Yury; Shyu, Andrew; Zhong, Hui; Roy, Roland R.; Edgerton, V. Reggie

2012-01-01

114

Variability in step training enhances locomotor recovery after a spinal cord injury.  

PubMed

Performance of a motor task is improved by practicing a specific task with added 'challenges' to a training regimen. We tested the hypothesis that, in the absence of brain control, the performance of a motor task is enhanced by training using specific variations of that task. We utilized modifications of step performance training to improve the ability of spinal rats to forward step. After a complete thoracic spinal cord transection, 20 adult rats were divided randomly to bipedally step on a treadmill in the forward, sideward, or backward direction for 28 sessions (20 min, 5 days/week) and subsequently tested for their ability to step in the forward direction. Although the animals from all trained groups showed improvement, the rats in the sideward-trained and backward-trained groups had greater step consistency and coordination along with higher peak amplitudes and total integrated activity of the rectified electromyographic signals from selected hindlimb muscles per step during forward stepping than the rats in the forward-trained group. Our results demonstrate that, by retaining the fundamental features of a motor task (bipedal stepping), the ability to perform that motor task can be enhanced by the addition of specific contextual variations to the task (direction of stepping). Our data suggest that the forward stepping neuronal locomotor networks are partially complemented by synchronous activation of interneuronal/motoneuronal populations that are also a part of the sideward or backward stepping locomotor networks. Accordingly, the overlap and interaction of neuronal elements may play a critical role in positive task transference. PMID:22591277

Shah, Prithvi K; Gerasimenko, Yury; Shyu, Andrew; Lavrov, Igor; Zhong, Hui; Roy, Roland R; Edgerton, Victor R

2012-07-01

115

Valve stem seal  

Microsoft Academic Search

A fixed valve stem oil seal for a piston-type internal combustion engine is described, comprising: a cup-shaped case having a radially extending flange with a central aperture for the acceptance of a valve stem and an axially extending portion positively engageable with a valve guide, and a seal element disposed between the radial flange on the case and the valve

B. F. Rericha; B. G. Stritzke

1989-01-01

116

Remote actuated valve implant  

DOEpatents

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.

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

117

Mitral valve surgery - open  

MedlinePLUS

... these is the mitral valve. The mitral valve opens so blood can flow from the left atria to the left ventricle. ... mitral regurgitation . A mitral valve that does not open fully will restrict blood flow. This is called mitral stenosis . A valve defect ...

118

Rotary pneumatic valve  

DOEpatents

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

Hardee, Harry C. (Albuquerque, NM)

1991-01-01

119

Muscle Strength and Damage Following Two Modes of Variable Resistance Training  

PubMed Central

Nautilus Machine (NM) and Elastic Resistance (ER) have gained considerable popularity among athletes and recreational lifters seeking to increase muscle strength. However, there is controversy concerning the use of ER for increasing muscle hypertrophy and strength among healthy-trained individuals. The aim of the study was to compare the effect of repeated near maximal contractions by ER/NM on indicators of muscle damage including: maximal strength decrement (MVIC), rate of muscle soreness (DOMS), concentration of plasma creatine kinase (CK) and increased high muscle signal on T2 weighted images using magnetic resonance imaging (MRI). Nine healthy male subjects completed two modalities of exercise (5 sets × 10RM ER/NM) in a counterbalance cross-over study design with three weeks “wash-out” period between experiments. The MVIC was measured and DOMS rated and recorded for 4 consecutive days while blood samples were collected on day 1, 3, 5 and 7. Prior to and forty eight hours after completion of each mode of exercise, subjects underwent MRI scanning. The average of applied forces demonstrated significantly higher value for NM compared with ER (362 ± 34.2 N vs 266.73 ± 44.6 N respectively) throughout the 5 sets of dynamic exercise (all p < 0.05). However, the indicators of muscle damage (T2 relaxation time, DOMS, MVIC and serum CK) exhibited a very similar response across both modes of training. Plasma CK increased significantly following both modes of training with the peak value on Day 3 (p < 0.05). The time course of muscle soreness reached a significant level after both modes of exercise and showed a peak value on the 2nd day (p < 0.05). The T2 relaxation time demonstrated a statistically significant increase following ER and NM compared with the pre-test value (p < 0.05). The similarity of these responses following both the ER and NM exercise training session suggests that both modes of training provide a similar training stress; despite a considerably lower external force generation during ER. The importance of these findings is underlined by the fact that exercise-induced muscle damage has been shown to be the underlying mechanism of further muscle hypertrophy. Key points Exercise induced muscle soreness increased levels of plasma CK, increased MRI T2 signal and prolonged strength loss indicate the moderate to intense nature of the training protocol. The similarity of these responses following both the Elastic Resistance and Nautilus Machine exercise training session suggests that both modes of training provide a similar training stress; despite a considerably lower external force generation during ER. The data in the present study suggest elastic training is a viable mode of resistance exercise that can provide a training stimulus greater than that employed in rehabilitation settings. PMID:24149552

Aboodarda, Saied Jalal; George, John; Mokhtar, Abdul Halim; Thompson, Martin

2011-01-01

120

Bellows sealed plug valve  

DOEpatents

A bellows sealed plug valve includes a valve body having an inlet passage and an outlet passage, a valve chamber between the inlet and outlet passages. A valve plug has substantially the same shape as the valve chamber and is rotatably disposed therein. A shaft is movable linearly in response to a signal from a valve actuator. A bellows is sealingly disposed between the valve chamber and the valve actuator and means are located between the bellows and the valve plug for converting linear movement of the shaft connected to the valve actuator to rotational movement of the plug. Various means are disclosed including helical thread mechanism, clevis mechanism and rack and pinion mechanism, all for converting linear motion to rotational motion.

Dukas, Jr., Stephen J. (Idaho Falls, ID)

1990-01-01

121

Valve for fluid control  

DOEpatents

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

Oborny, Michael C. (Albuquerque, NM); Paul, Phillip H. (Livermore, CA); Hencken, Kenneth R. (Pleasanton, CA); Frye-Mason, Gregory C. (Cedar Crest, NM); Manginell, Ronald P. (Albuquerque, NM)

2001-01-01

122

Effectiveness of mask ventilation in a training mannikin. A comparison between the Oxylator EM100 and the bag-valve device  

Microsoft Academic Search

The demands for an optimal ventilation apparatus are that it can be easily handled, achieves a sufficiently high ventilation volume, and minimizes gastric inflation. Our aim was therefore to carry out a study in a training mannikin to find out whether the Oxylator EM100, compared with the bag, obtains improved ventilation and a decrease in gastric inflation. In a randomized

Joseph J Osterwalder; W Schuhwerk

1998-01-01

123

Effectiveness of mask ventilation in a training mannikin. A comparison between the Oxylator EM100 and the bag-valve device  

Microsoft Academic Search

The demands for an optimal ventilation apparatus are that it can be easily handled, achieves a sufficiently high ventilation volume, and minimizes gastric inflation. Our aim was therefore to carry out a study in a training mannikin to find out whether the Oxylator EM100, compared with the bag, obtains improved ventilation and a decrease in gastric inflation. In a randomized

Joseph J. Osterwalder; W. Schuhwerk

124

Effects of strength and power training on neuromuscular variables in older adults.  

PubMed

The purpose of this study was to compare the neuromuscular adaptations produced by strength-training (ST) and power-training (PT) regimens in older individuals. Participants were balanced by quadriceps cross-sectional area (CSA) and leg-press 1-repetition maximum and randomly assigned to an ST group (n = 14; 63.6 ± 4.0 yr, 79.7 ± 17.2 kg, and 163.9 ± 9.8 cm), a PT group (n = 16; 64.9 ± 3.9 yr, 63.9 ± 11.9 kg, and 157.4 ± 7.7 cm), or a control group (n = 13; 63.0 ± 4.0 yr, 67.2 ± 10.8 kg, and 159.8 ± 6.8 cm). ST and PT were equally effective in increasing (a) maximum dynamic and isometric strength (p < .05), (b) increasing quadriceps muscle CSA (p < .05), and (c) decreasing electrical mechanical delay of the vastus lateralis muscle (p < .05). There were no significant changes in neuromuscular activation after training. The novel finding of the current study is that PT seems to be an attractive alternative to regular ST to maintain and improve muscle mass. PMID:22472578

Wallerstein, Lilian França; Tricoli, Valmor; Barroso, Renato; Rodacki A, L F; Russo, Luciano; Aihara, André Yui; da Rocha Correa Fernandes, Artur; de Mello, Marco Tulio; Ugrinowitsch, Carlos

2012-04-01

125

The Role of Aerobic and Anaerobic Training Programs on CD34+ Stem Cells and Chosen Physiological Variables  

PubMed Central

Exercise is one of the most powerful non-pharmacological strategies, which can affect nearly all cells and organs in the body. Changes in the behavior of adult stem cells have been shown to occur in response to exercise. Exercise may act on regenerative potential of tissues by altering the ability to generate new stem cells and differentiated cells that are able to carry out tissue specific functions. The purpose of this study was to reveal the role of aerobic and anaerobic training programs on CD34+ Stem Cells and chosen physiological variables. Twenty healthy male athletes aged 18–24 years were recruited for this study. Healthy low active males and BMI matched participants (n=10) aged 20–22 years were recruited as controls. Aerobic and anaerobic training programs for 12 weeks were conducted. VO2max pulse observation was carried out using the Astrand Rhyming protocol. RBCs, WBCs, HB and hematocrit were estimated using a coulter counter, lactate by the Accusport apparatus, CD34+ stem cells by flow cytometry. VO2max was increased significantly in case of the aerobic training program compared to anaerobic one (62±2.2 ml/kg/min vs. 54±2.1 ml/kg/min). Haemotological values increased significantly in the anaerobic program when compared to the aerobic one, RBCs (5.3±0.3 and 4.9±0.2 mln/ul), WBCs (6.6±0.5 and 6.1±0.4 thous/ul), HB (15.4±0.4 and 14.2±0.5 g/de), Hematocrit (4.6±1.2 and 4.4±1.1 %), CD34+ stem cells count increased significantly in case of the anaerobic program compared to the aerobic (251.6±21.64 and 130±14.61) and sedentary one (172±24.10). These findings suggest that anaerobic training programs provoke better adaptation to exercise and stem cell counts may differ between trained and sedentary subjects. Circulating immature cells are likely to be involved in angiogenesis and repair process, both mechanisms being associated with strenuous exercise. Knowledge of the physiological effects of training on stem cells might be of potential clinical use. PMID:23486555

Shalaby, Mohammed Nader; Saad, Mohammed; Akar, Samy; Reda, Mubarak Abdelreda Ali; Shalgham, Ahmed

2012-01-01

126

Fast acting check valve  

NASA Technical Reports Server (NTRS)

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

Perkins, Gerald S. (Inventor)

1979-01-01

127

Transcatheter aortic valve implantation  

PubMed Central

Transcatheter aortic valve implantation was developed to offer a therapeutic solution to patients with severe symptomatic aortic stenosis who are not candidates for conventional aortic valve replacement. The improvement in transcatheter aortic valve implantation outcomes is still of concern in the areas of stroke, vascular injury, heart block, paravalvular regurgitation and valve durability. Concomitantly, the progress, both technical and in terms of material advances of transcatheter valve systems, as well as in patient selection, renders transcatheter aortic valve implantation an increasingly viable treatment for more and more patients with structural heart disease. PMID:25374670

Oliemy, Ahmed

2014-01-01

128

Optimization of Valve Disc Using Orthogonal Array and Kriging Model  

NASA Astrophysics Data System (ADS)

A butterfly valve is a type of flow control device, typically used to regulate a fluid flowing. Currently, FEA is often used to predict the safety in the design of valve disc. Also, the study about the affection of butterfly valve's disc to the valve flow characteristics by using CFD has been done by many researchers. Along with the development of computer technique, design and analysis of computer experiments has becoming more and more important in engineering design and optimization. Hereinto Kriging model is one popular analysis approach for the purpose of creating a cheap "meta-model" as a surrogate to a computationally expensive simulation model. In this paper, the numerical analysis considered the strength, pressure loss coefficient and weight of valve disc simultaneously is investigated to improve the shape of a traditional butterfly valve disc. Firstly, an initial model of butterfly valve is made to evaluate the performance of the valve disc by using CFD and FEM. Then several experiments with different variables combination of the valve disc are conducted by mean of orthogonal array. Finally, the Kriging model is used to find the optimum variables combination of valve disc based on the result of computer experiments. In addition, the optimum result is verified by FEA and CFD simulation again. The result shows that compared with traditional computer experiments, optimization by using Kriging model can improve the weight of the valve disc very effectively in a short time.

Song, Xueguan; Wang, Lin; Kang, Jungho; Kim, Seung Gyu; Jo, Young Jik; Park, Youngchul

2008-10-01

129

Variability of Response Latency in Paired Associate Learning as a Function of Training Procedure.  

ERIC Educational Resources Information Center

Two procedures were investigated in an attempt to decrease the variability of overlearning response latencies in a study-test paradigm, paired-associate task matching CVC's with response keys: (1) self-pacing the task by presenting test trial stimuli whenever the subject pressed a "home" key; and (2) instructing and shaping subjects to keep home…

Judd, Wilson A.; Glaser, Robert

130

Pulmonary valve stenosis  

MedlinePLUS

... stenosis; Heart valve pulmonary stenosis; Pulmonary stenosis; Stenosis - pulmonary valve; Balloon valvuloplasty - pulmonary ... water pills) Treat abnormal heartbeats and rhythms Percutaneous balloon pulmonary dilation (valvuloplasty) may be performed when no other ...

131

Valve Health Monitor (VHM)  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

132

Mitral Valve Prolapse  

MedlinePLUS

... the 2 flaps of the mitral valve swing open to let blood flow from the atrium to the ventricle. The flaps normally open only one way and the blood only flows one way. What is mitral valve prolapse? If ...

133

Pump isolation valve  

DOEpatents

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

Kinney, Calvin L. (Penn Hills, PA); Wetherill, Todd M. (Lower Burrell, PA)

1983-08-02

134

Thermal expansion check valve  

Microsoft Academic Search

A ball check valve is provided for use in a thermosiphoning solar energy system. The valve is extremely sensitive to low pressure variations and will permit reverse thermosiphoning above specified operating temperatures.

Sigworth

1982-01-01

135

Heart valve surgery  

MedlinePLUS

... through. They then close, keeping blood from flowing backward. There are four valves in your heart: Aortic ... all the way will allow blood to leak backwards. This is called regurgitation. A valve that does ...

136

Stemless Ball Valve  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

137

HVDC Thyristor Valve Development  

Microsoft Academic Search

The development of the thyristor valve technology from the first designed air-cooled thyristor valve to the modern water-cooled thyristor valve is described. The design and design criteria for the modern water-cooled valve are briefly described. The performance of the previous air-cooled design and the water-cooled design is compared especially with regard to power handling capability including overload capacity, power losses,

Ake Ekstrom; Lars Eklund

1987-01-01

138

Overflow control valve  

DOEpatents

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

Hundal, Rolv (Hempfield, PA); Kessinger, Boyd A. (Murrysville, PA); Parlak, Edward A. (North Huntingdon, PA)

1984-07-24

139

Aerodynamic Shutoff Valve  

NASA Technical Reports Server (NTRS)

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

Horstman, Raymond H.

1992-01-01

140

Pilot study employing heart rate variability biofeedback training to decrease anxiety in patients with eating disorders  

PubMed Central

Heart rate variability (HRV) biofeedback, a technique which encourages slow meditative breathing, was offered to 25 in-patients with various eating disorder diagnoses-anorexia nervosa, bulimia nervosa and binge eating disorder. We found that this modality had no serious side effects, and was subjectively useful to most participants. An enhanced ability to generate highly coherent HRV patterns in patients with recent onset anorexia nervosa was observed. PMID:24917934

2014-01-01

141

Artificial Heart Valve Design  

E-print Network

of the heart valve tissue · Years of high blood pressure and/or years of heavy alcohol drinking can cause direction flow of blood through the heart · Heart valves allow blood to flow through in a forward direction, but does not let any blood through in the opposite direction #12;Why does a heart valve start leaking

Provancher, William

142

Heart Valve Disease  

MedlinePLUS

... ay-OR-tik) valves. These valves have tissue flaps that open and close with each heartbeat. The flaps make sure blood flows in the right direction ... is due to prolapse. "Prolapse" is when the flaps of the valve flop or bulge back into ...

143

Purge flow control valve  

Microsoft Academic Search

This patent describes a valve for controlling purge of fuel vapor to an engine having an induction passage for air flow to the engine and a throttle in the induction passage rotatable between closed and open positions for controlling air flow therethrough. The valve comprises a housing having an inlet for fuel vapor, a valve seat surrounding the inlet, a

C. M. De Minco; M. J. Field; D. E. Serth

1987-01-01

144

Mitral Valve Prolapse  

PubMed Central

The author discusses the pathophysiology of mitral valve prolapse and provides guidelines to identify and treat low-to high-risk mitral valve prolapse. An approach to diagnosing bacterial endocarditis and its prophylaxis are also discussed. The author reviews mitral valve prolapse syndrome and the risk of sudden death.

Rosser, Walter W.

1992-01-01

145

Fuel injection control valve  

Microsoft Academic Search

This patent describes a rotary combustion engine having first and second fuel injection nozzles, a fuel supply system comprising: a fuel tank; a supply pump with an inlet communicating with the fuel tank; an engine driver fuel injector pump; and a fuel supply valve comprising: a housing defining a valve bore, a first inlet communicating the valve bore with the

Poore

1987-01-01

146

Dump valve assembly  

DOEpatents

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

Owen, T.J.

1984-01-01

147

Thermally actuated valve  

NASA Technical Reports Server (NTRS)

Effective seal in one-shot valve is made by shrink-fitting ball within cylinder; thermal expansion of cylinder, caused by contiguous source of heat, will release ball and open valve. Valve can also be adapted for repeated operation and made capable of being opened without pressurized fluid.

Silver, R. H.

1973-01-01

148

Liquid rocket valve assemblies  

NASA Technical Reports Server (NTRS)

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

1973-01-01

149

Mitral valve replacement with ball valve prostheses  

PubMed Central

Our experience with ball valve replacement of the mitral valve during the past decade is presented in terms that allow comparison with other techniques. The use of such prostheses is characterized by ease of implantation, with an overall operative mortality of 11 per cent for isolated mitral replacement and 13 per cent for multiple valve replacement. The operative mortality for isolated mitral valve replacement during 1969 and thus far in 1970 has been nil. The late mortality was 13 per cent for isolated mitral replacement and 20 per cent for multiple valve replacement. Forty-three per cent of the total late deaths were clearly unrelated to the prosthetic device itself. The overall incidence of late infection and leak is less than 1 per cent and the immediate haemodynamic benefit is not altered by loss of structural integrity of the prosthesis. The most serious problem after mitral valve replacement with the ball valve prosthesis is that of thromboembolic complications. While thrombotic stenosis of the prosthesis is a rarity, embolic episodes, usually cerebral in type, have been noted in 63 per cent of the patients surviving mitral valve replacement with the earliest model ball valve from August 1960 to February 1966. Improvements in valve design have resulted in a remarkable decrease in this incidence as examined by actuarial techniques and taking into account the duration of follow-up. The extension of the cloth sewing margins to the orifice of the valve while maintaining a metallic orifice and metallic cage (Model 6120) resulted in a drop of the thromboembolic rate to 17 per cent from April 1965 to April 1969. The development of the totally cloth-covered prosthesis has further improved these results, with only one thromboembolic complication after isolated mitral valve replacement with the Model 6310 valve in a series of 66 consecutive patients. In clinical practice this has resulted in the avoidance of the use of anticoagulant therapy in patients in whom for a variety of reasons this carries an increased hazard. With further follow-up it may be possible to discontinue the routine use of anticoagulants. Images PMID:5572646

Starr, Albert

1971-01-01

150

Compact valve actuation mechanism  

NASA Technical Reports Server (NTRS)

A valve actuation device. The device may include a free floating valve bridge movably supported within a cavity in the engine housing. The bridge may be provided with a cavity and an orifice arrangement for pumping gases entrained with lubricating fluid toward the piston stems as the bridge reciprocates back and forth. The device may also include a rocker arm that has a U-shaped cross-sectional shape for receiving at least a portion of the valve bridge, valve stem valve spring and spring retainer therein. The rocker arm may be provided with lubrication passages for directing lubrication to the point wherein it is pivotally affixed to the engine housing.

Brogdon, James William (Inventor); Gill, David Keith (Inventor)

2000-01-01

151

Variable venturi type carburetor  

SciTech Connect

A variable venturi type carburetor is described comprising a carburetor body provided with a suction passage therein for flow of air through the passage, a slide valve supported by the body for slidable movement across the suction passage to serve as a variable venturi, a butterfly throttle valve pivotably supported by the carburetor body downstream of the slide valve, interlocking means connecting the slide valve and the butterfly throttle valve together for operating in correspondence with one another, operating means connected to one of the valves for operating the same by application of an external force thereto. A low-speed fuel nozzle opens into the suction passage in the vicinity of the butterfly throttle valve, an intermediate and a high speed main fuel nozzle opens into the suction passage opposite the slide valve, and a low and intermediate-speed primary fuel nozzle opens into the suction passage between the slide valve and the butterfly throttle valve. The slide valve includes a bottom portion having a front side surface facing upstream in the suction passage and a rear side surface facing downstream in the suction passage, the front and rear side surfaces having lower edges which are located in the same horizontal plane, the rear side surface being provided with an inverted cutaway.

Tahata, M.

1986-09-02

152

[Valve-in-valve replacement of primary tissue valve failure of bovine pericardial valve minor].  

PubMed

A 73-year-old woman who underwent mitral valve replacement with a 31 mm Carpentier Edwards Pericardial Xenograft 19 years ago. She revealed sudden onset of a grade IV/VI a seagull like diastolic murmur at the apex, and severe hematuria. Echocardiography demonstrated severe mitral regurgitation. These findings were consistent with acute primary tissue valve failure. Therefore we performed emergency reoperation. At operation, valve leaflet was torn at the commissural stitch, and bioprosthesis strut was buried in the left posterior ventricular wall. The mitral prosthetic valve replaced with a 25 mm CarboMedics OptiForm using a technique of valve-in-valve replacement. This procedure would be one option for replacement of bioprosthetic mitral valve. PMID:16440687

Tateishi, M; Koide, M; Kunii, Y; Watanabe, K; Ohsawa, M

2006-01-01

153

Global Variability of Mesoscale Convective System Anvil Structure from A-Train Satellite Data  

NASA Technical Reports Server (NTRS)

Mesoscale convective systems (MCSs) in the tropics produce extensive anvil clouds, which significantly affect the transfer of radiation. This study develops an objective method to identify MCSs and their anvils by combining data from three A-train satellite instruments: Moderate Resolution Imaging Spectroradiometer (MODIS) for cloud-top size and coldness, Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) for rain area size and intensity, and CloudSat for horizontal and vertical dimensions of anvils. The authors distinguish three types of MCSs: small and large separated MCSs and connected MCSs. The latter are MCSs sharing a contiguous rain area. Mapping of the objectively identified MCSs shows patterns of MCSs that are consistent with previous studies of tropical convection, with separated MCSs dominant over Africa and the Amazon regions and connected MCSs favored over the warm pool of the Indian and west Pacific Oceans. By separating the anvil from the raining regions of MCSs, this study leads to quantitative global maps of anvil coverage. These maps are consistent with the MCS analysis, and they lay the foundation for estimating the global radiative effects of anvil clouds. CloudSat radar data show that the modal thickness of MCS anvils is about 4-5 km. Anvils are mostly confined to within 1.5-2 times the equivalent radii of the primary rain areas of the MCSs. Over the warm pool, they may extend out to about 5 times the rain area radii. The warm ocean MCSs tend to have thicker non-raining and lightly raining anvils near the edges

Yuan, Jian; Houze, Robert A.

2010-01-01

154

Simulation of a Hydraulic Pump Control Valve  

NASA Technical Reports Server (NTRS)

This paper describes the mode of operation of a control valve assembly that is used with a hydraulic pump. The operating system of the valve is modelled in a simplified form, and an analogy for hydraulic resonance of the pressure sensing system is presented. For the control valve investigated, air entrainment, length and diameter of the resonator neck, and valve mass produced the greatest shift in resonant frequency. Experimental work was conducted on the hydraulic system so that the resonance levels and frequencies could be measured and the accuracy of the theory verified. The results obtained make it possible to evaluate what changes to any of the variables considered would be most effective in driving the second harmonic frequency above the operating range.

Molen, G. Vander; Akers, A.

1987-01-01

155

Serial correlation in neural spike trains: Experimental evidence, stochastic modeling, and single neuron variability  

NASA Astrophysics Data System (ADS)

The activity of spiking neurons is frequently described by renewal point process models that assume the statistical independence and identical distribution of the intervals between action potentials. However, the assumption of independent intervals must be questioned for many different types of neurons. We review experimental studies that reported the feature of a negative serial correlation of neighboring intervals, commonly observed in neurons in the sensory periphery as well as in central neurons, notably in the mammalian cortex. In our experiments we observed the same short-lived negative serial dependence of intervals in the spontaneous activity of mushroom body extrinsic neurons in the honeybee. To model serial interval correlations of arbitrary lags, we suggest a family of autoregressive point processes. Its marginal interval distribution is described by the generalized gamma model, which includes as special cases the log-normal and gamma distributions, which have been widely used to characterize regular spiking neurons. In numeric simulations we investigated how serial correlation affects the variance of the neural spike count. We show that the experimentally confirmed negative correlation reduces single-neuron variability, as quantified by the Fano factor, by up to 50%, which favors the transmission of a rate code. We argue that the feature of a negative serial correlation is likely to be common to the class of spike-frequency-adapting neurons and that it might have been largely overlooked in extracellular single-unit recordings due to spike sorting errors.

Farkhooi, Farzad; Strube-Bloss, Martin F.; Nawrot, Martin P.

2009-02-01

156

INFLUENCE OF NUMBER OF SETS ON BLOOD PRESSURE AND HEART RATE VARIABILITY AFTER A STRENGTH TRAINING SESSION.  

PubMed

The purpose of this study was to compare the acute effects of one, three and five sets of strength training (ST), on heart rate variability (HRV) and blood pressure. Eleven male volunteers (age: 26.1 ± 3.6 years; body mass: 74.1 ± 8.1 kg; height: 172 ± 4 cm) with at least six months prior experience in ST participated in the study. After determining the one repetition-maximum load (1RM) for the bench press (BP), lat pull down (LPD), shoulder press (SP), biceps curl (BC), triceps extension (TE), leg press (LP), leg extension (LE) and leg curl (LC), the participants performed three different exercise sequences in a random order and 72 hours apart. During the first sequence, subjects performed a single set of 8-10 repetitions, at 70% 1RM, and with 2 minutes rest interval between exercises. Exercises were performed in the following order: BP, LPD, SP, BC, TE, LP, LE, and LC. During the second sequence, subjects performed the same exercise sequence, with the same intensity, two minutes rest interval between sets and exercises, but with three consecutive sets of each exercise. During the third sequence, the same protocol was followed but with five sets of each exercise. Before and after the training sessions, blood pressure and HRV were measured. The statistical analysis demonstrated a greater duration of post exercise hypotension following the 5-set program versus the 1-set or 3-sets (p<0.05). However, the 5-set program promoted a substantial cardiac stress, as demonstrated by HRV (p<0.05). These results indicate that 5-sets of 8 to 10 repetitions at 70% 1-RM load may provide the ideal stimulus for a post-exercise hypotensive response. Therefore, ST composed of upper and lower body exercises and performed with high volumes are capable of producing significant and extended post-exercise hypotensive response. In conclusion, strength and conditioning professionals can prescribe five sets per exercises if the goal is to reduce blood pressure after training. In addition, these findings may have importance, specifically in the early phase of high blood pressure development, but more research is needed in hypertensive populations to validate this hypothesis. PMID:25436620

Figueiredo, Tiago; Rhea, Matthew R; Peterson, Mark; Miranda, Humberto; Bentes, Claudio M; Machado de Ribeiro Dos Reis, Victor Manuel; Simão, Roberto

2014-11-26

157

Design and dynamic simulation of a fixed pitch 56 kW wind turbine drive train with a continuously variable transmission  

NASA Technical Reports Server (NTRS)

The dynamic analysis of a horizontal axis fixed pitch wind turbine generator (WTG) rated at 56 kW is discussed. A mechanical Continuously Variable Transmission (CVT) was incorporated in the drive train to provide variable speed operation capability. One goal of the dynamic analysis was to determine if variable speed operation, by means of a mechanical CVT, is capable of capturing the transient power in the WTG/wind environment. Another goal was to determine the extent of power regulation possible with CVT operation.

Gallo, C.; Kasuba, R.; Pintz, A.; Spring, J.

1986-01-01

158

A Simple Automated Valve  

Microsoft Academic Search

We have developed a simple computer controlled valve based on the popular Nupro B-4HK bellows valve. The valve is controlled by a stepping motor (Donovan Micro-Tek Inc.) using a Motorola MC3479 driver. TTL level input signals to the driver actuate the motor. With this stepping motor\\/driver combination it is possible to independently set the CW and CCW torque of the

R. J. Rollefson; F. M. Ellis

2001-01-01

159

Lined 10'' butterfly valve outlasts competitive valves in brine filter system  

SciTech Connect

One of the world's largest chlorine production units located in the Gulf Coast area has an extensive brine piping system with a large number of valves. Some of the valves performed well but many failed to meet the service requirements, especially in the brine filtering system with the salt solution at ambient temperatures and pressures about 100 psi. One of these was a 10'' valve. Various types of gear-operated butterfly valves, with an elastomer lining to withstand the somewhat corrosive solution, had been tried but developed leaks and had to be repaired or replaced after 4 to 6 months. The valves became difficult or impossible to operate in some cases when brine leaking past the stem seal attacked the inner surface of the metal valve body and the liner was dislodged by the movement of the disc. In September 1980, a 10'' butterfly valve specifically designed for bubble-tight shut off and zero stem leakage was installed in the brine filter line on a trial basis. The valve has a 1-piece, epoxy-coated ductile iron body with a molded one-piece liner of Hypalon rubber, and a stainless steel stem and disc with splines instead of pins to provide a trouble-free connection. The stem is positively sealed against leakage by a patented spherical machining process on both the disc and the liner. The valve was furnished with a variable ratio gear actuator that has higher torque output when the disc begins to make contact with the seat to assure a bubble-tight shutoff with minimum input torque. The butterfly valve has provided leaktight performance since it was installed in September 1980 and is still easy to open and close by the geared actuator.

Gaines, A.

1982-03-01

160

Mitral replacement: clinical experience with a ball-valve prosthesis. Twenty-five years later.  

PubMed Central

The purpose of this report is to review the results of mitral valve replacement since a first report in the Annals of Surgery in 1961, in order to determine the relative importance of new valve designs versus other surgical variables. The continued use of the silastic ball valve in its 1966 configuration (Model 6120), by providing a comparative data base for other new prosthetic valves, allows this analysis. For a valid comparison with the tilting disc (Bjork-Shiley) and the porcine (Hancock and Carpentier-Edwards) valves, only results with the silastic ball valves implanted during comparable time frames should be used. (Formula: see text) Thus, there are no significant differences in the results obtained with the silastic ball valve in time frames comparable to other contemporary valves introduced in the early 1970s. Improved results, therefore, must be non-prosthetic valve related. Images FIG. 1. FIG. 2. FIG. 3. PMID:4037910

Cobanoglu, A; Grunkemeier, G L; Aru, G M; McKinley, C L; Starr, A

1985-01-01

161

Recently patented transcatheter aortic valves in clinical trials.  

PubMed

The most widely used heart valve worldwide is the Edwards Sapien, which currently has 60% of the worldwide transcatheter aortic valve implantation (TAVI) market. The CoreValve is next in line in popularity, encompassing 35% of the worldwide TAVI market. Although these two valves dominate the TAVI market, a number of newer transcatheter valves have been introduced and others are in early clinical evaluation. The new valves are designed to reduce catheter delivery diameter, improve ease of positioning and sealing, and facilitate repositioning or removal. The most recent transcatheter valves for transapical use include Acurate TA (Symetis), Engager (Medtronic), and JenaValve the Portico (St Jude), Sadra Lotus Medical (Boston Scientific), and the Direct Flow Medical. These new inventions may introduce more effective treatment options for high-risk patients with severe aortic stenosis. Improvements in transcatheter valves and the developing variability among them may allow for more tailored approaches with respect to patient's anatomy, while giving operators the opportunity to choose devices they feel more comfortable with. Moreover, introducing new devices to the market will create a competitive environment among producers that will reduce high prices and expand availability. The present review article includes a discussion of recent patents related to Transcatheter Aortic Valves. PMID:24279506

Neragi-Miandoab, Siyamek; Skripochnik, Edvard; Salemi, Arash; Girardi, Leonard

2013-12-01

162

Study of Mitral Valve in Human Cadaveric Hearts  

PubMed Central

Objectives: The mitral valve is a complex structure that is altered by disease states. The classical image of the mitral valve is a bicuspid valve with two leaflets and two papillary muscles. The reason for the present study is to study the morphology and morphometry of the mitral valve. Materials and Methods: This study was carried out on 116 human cadaveric hearts. Hearts were opened along the left border through the atrioventricular valve. The diameter and circumference of the annulus was measured and the number of valve leaflets was observed. Results: The mean annular diameter was 2.22 cm. The mean circumference of mitral valve annulus was 9.12 cm. The standard description of the mitral valve is bicuspid. In the present study, we found the number of cusps to be variable, from monocuspid to hexacuspid and classified them accordingly. Conclusions: The mitral valve is not always a bicuspid valve. The number of cusps varies greatly. An increase in the number of the cusp and their improper approximation most likely causes various valvular disorders. PMID:23439693

Gunnal, S. A.; Farooqui, M. S.; Wabale, R. N.

2012-01-01

163

Triple Starr Valve Replacement  

PubMed Central

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

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

1969-01-01

164

Tubing drain valve  

SciTech Connect

A method is described for operating a valve means. The valve means comprises a tubular piston movable within a tubular member suitable for use in a borehole pipe string to open and close a port through the wall of the tubular member. The method comprises: biassing the valve means in its closed position; pressurizing the interior of the piston to a predetermined pressure to overcome the biassing closed force and to actuate the valve means to its open position; biassing the valve means to its open position; and actuating the valve means to its closed position by engaging a first arm of a dog pivotally mounted on the piston with an engaging means insertable through the interior of the tubular piston; moving the piston relative to the tubular member; rotating the dog about its pivot to bring a second arm of the dog into contact with a detent in the tubular member; and applying sufficient force to the first arm to continue rotating the dog about the pivot, while engaging the detent with the second arm of the dog, in order to overcome the biassing open force to actuate the valve means to its closed position. A tubing drain valve suitable for use in a borehole pipe string, comprising: a sub suitable for incorporating within a borehole pipe string; and a port between the interior and the exterior of the sub; and valve means for opening and closing the port.

Soderberg, P.B.

1987-02-24

165

Aortic or Mitral Valve Replacement With the Biocor and Biocor Supra  

ClinicalTrials.gov

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

2014-08-08

166

Optimising BMW four-cylinder two-valve engines Optimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOpt  

Microsoft Academic Search

In model year 1994, BMW will present two essentially redesigned 4-cylinder, 2-valve engines. BMW has upgraded its 1.6 1 and 1.8 1 2-valve engines using technical features previously reserved for the 4-valve engines, such as knock control system, distributorless semiconductor ignition, variable induction system (DISA) and ribbed V-belt accessory drive, along with measures to reduce power losses, noise levels and

R. Flierl; F. Kramer; H. Rech; U. Stanski; M. Wenzel

1993-01-01

167

Use of a Melody Pulmonary Valve in Transcatheter Valve-in-Valve Replacement for Tricuspid Valve Bioprosthesis Degeneration  

PubMed Central

Bioprosthetic heart valves can degenerate and fail over time. Repeat surgery as a means of replacement increases morbidity and mortality rates, and some patients are not candidates for reoperation. A newer treatment, percutaneous transcatheter valve-in-valve implantation, might delay or substitute for invasive procedures. We present the case of a 51-year-old woman, a poor candidate for surgery who had prosthetic tricuspid valve degeneration and stenosis. We successfully performed valve-in-valve placement of a Melody® valve, using a procedure originally intended to treat pulmonary valve conduit obstruction or regurgitation. To our knowledge, this is among the first case reports to describe the use of the Melody pulmonary valve in transcatheter valve-in-valve replacement for prosthetic tricuspid stenosis that was otherwise not correctable. Additional data and longer follow-up periods are necessary to gain an understanding of ideal indications and selection of patients for the percutaneous transcatheter treatment of tricuspid valve stenosis. PMID:25425984

Snipelisky, David F.; Shapiro, Brian P.

2014-01-01

168

A piezoelectrically actuated ball valve  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

169

[Modulator effect of socio-emotional variables on training in elaboration strategies in Compulsory Secondary Education (CSE): paraphrase and applications].  

PubMed

The purpose of this work is to verify the modulation of motivation, self-concept, and causal attributions in the efficacy of a training program of strategies to elaborate information in the stage of Compulsory Secondary Education (CSE). We selected 328 students from CSE, 179 from second grade and 149 from fourth grade, and three measurement moments: pretest, posttest, and follow-up. The results indicate greater use of learning strategies by students with higher intrinsic motivation, in contrast to students with higher extrinsic motivation, who use learning strategies less frequently. With regard to self-concept, the results differ as a function of the course. In second grade, we found modulation of the variable Academic self-concept, whereas in fourth grade, such modulation is produced by General self-concept and Private self-concept. In general, there is a tendency towards more enduring significant improvements in students with medium and high self-concept, especially in their perception of the use of strategies or in complex tasks that involve relating the contents to be learned with experiences from their daily life. However, students with low self-concept significantly improve strategies associated with learning how to perform specific tasks. PMID:22269361

Martín-Antón, Luis Jorge; Carbonero Martín, Miguel Angel; Román Sánchez, José María

2012-02-01

170

Preliminary characterization of active MEMS valves.  

SciTech Connect

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

Barnard, Casey Anderson

2010-08-01

171

Non-plugging injection valve  

DOEpatents

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

Carey, Jr., Henry S. (Wilsonville, AL)

1985-01-01

172

Gas flow control valve  

Microsoft Academic Search

A compact gas flow control valve is described comprising a valve body having a first, rotor cavity-defining portion and a second cover portion covering the rotor cavity, at least one of the body portions including inlet means communicating with the rotor chamber for receiving gas under pressure for providing the gas to the rotor chamber, at least one of the

J. R. Phlipot; S. R. Pinkston; H. Nurre

1988-01-01

173

Power Plant Valves  

NASA Technical Reports Server (NTRS)

Rockwell International employed NASTRAN to identify high stress areas in valve products and the mechanical configurations necessary to accommodate them. Also used in seismic and vibration analysis of valves to establish design adequacy under severe conditions, such as those that might occur in an earthquake. Program offers significant savings in analysis effort compared with other analytical approaches.

1981-01-01

174

Rotary selector valve  

Microsoft Academic Search

This paper discusses a multi-port valve which internally supports a rotatable trunnion having an elbow passage between a nozzle portion of the trunnion and a lower end outlet that communicates with a test port of the valve body. The outer end of the nozzle has an axially reciprocable hollow seal piston with a seal support ring whose outer face is

J. A. Jones; J. W. Herndon

1991-01-01

175

Robotic mitral valve surgery  

Microsoft Academic Search

Traditionally mitral valve surgery has been performed via median sternotomy. However, a renaissance in cardiac surgery is occurring. Cardiac operations are being performed through smaller and alternative incisions with enhanced technological assistance. Specifically, minimally invasive mitral valve surgery has become standard for many surgeons. At our institution, we have developed a robotic mitral surgery program with the da VinciTM telemanipulation

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

2003-01-01

176

Aortic valve surgery - open  

MedlinePLUS

... connects the heart and aorta. The aortic valve opens so blood can flow out. It then closes to keep blood from ... called aortic regurgitation. Your aortic valve does not open fully so blood flow through it is reduced. This is called aortic ...

177

Central flow tilting disc valve for aortic valve replacement  

PubMed Central

A new central flow tilting disc valve has been introduced. The clinical experience from the first 50 patients treated with aortic valve replacement and followed up for 12 months is reported. The results obtained are so encouraging that the tilting disc valve is at present preferred for all aortic valve replacements in this institution. Images PMID:5485003

Björk, Viking Olov

1970-01-01

178

Infective mitral valve endocarditis after transapical aortic valve implantation  

PubMed Central

An 80-year old patient underwent a transapical aortic valve implantation. On the 28th postoperative day, the patient developed acute mitral valve endocarditis. Initially, the patient was unsuccessfully treated conservatively. After 71 days, the patient was operated on with mitral valve replacement. In this report, we discuss the potentially growing problem of complications related to transcatheter valve implantation. PMID:23223669

Hirnle, Grzegorz; Holzhey, David; Borger, Michael; Mohr, Friedrich-Wilhelm

2013-01-01

179

Echocardiography in Transcatheter Aortic Valve Implantation and Mitral Valve Clip  

PubMed Central

Transcatheter aortic valve implantation and transcatheter mitral valve repair (MitraClip) procedures have been performed worldwide. In this paper, we review the use of two-dimensional and three-dimensional transesophageal echo for guiding transcatheter aortic valve replacement and mitral valve repair. PMID:23019387

Luo, Huai

2012-01-01

180

The effect of a complex training and detraining programme on selected strength and power variables in early pubertal boys.  

PubMed

Complex training, a combination of resistance training and plyometrics is growing in popularity, despite limited support for its efficacy. In pre- and early pubertal children, the study of complex training has been limited, and to our knowledge an examination of its effect on anaerobic performance characteristics of the upper and lower body has not been undertaken. Furthermore, the effect of detraining after complex training requires clarification. The physical characteristics (mean+/-s) of the 54 male participants in the present study were as follows: age 12.3 +/- 0.3 years, height 1.57 +/- 0.07 m, body mass 50.3 +/- 11.0 kg. Participants were randomly assigned to an experimental (n = 33) or control group (n = 21). The training, which was performed three times a week for 12 weeks, included a combination of dynamic constant external resistance and plyometrics. After training, participants completed 12 weeks of detraining. At baseline, after training and after detraining, peak and mean anaerobic power, dynamic strength and athletic performance were assessed. Twenty-six participants completed the training and none reported any training-related injury. Complex training was associated with small increases (< or =5.5%) in peak and mean power during training, followed by decreases of a similar magnitude (< or = -5.9%) during detraining (P < 0.05). No changes or minor, progressive increases (< or =1.5%) were evident in the control group (P > 0.05). In the experimental group, dynamic strength was increased by 24.3 - 71.4% (dependent on muscle group; P < 0.01), whereas growth-related changes in the control group varied from 0 to 4.4% (P > 0.05). For 40-m sprint running, basketball chest pass and vertical jump test performance, the experimental group saw a small improvement (< or =4.0%) after training followed by a decline (< or = -4.4%) towards baseline during detraining (P < 0.05), whereas the control group experienced no change (P > 0.05). In conclusion, in pre- and early pubertal boys, upper and lower body complex training is a time-effective and safe training modality that confers small improvements in anaerobic power and jumping, throwing and sprinting performance, and marked improvements in dynamic strength. However, after detraining, the benefits of complex training are lost at similar rates to other training modalities. PMID:16882633

Ingle, Lee; Sleap, Mike; Tolfrey, Keith

2006-09-01

181

Transcatheter CoreValve valve-in-valve implantation in a stentless porcine aortic valve for severe aortic regurgitation  

PubMed Central

Key Clinical Message We describe the first valve-in-valve Corevalve transcatheter aortic valve replacement in the St. Jude Toronto stentless porcine aortic valve in the United States, which enabled this 59-year-old patient with a history of bacterial endocarditis and aortic regurgitation to avoid heart transplant with complete resolution of his severe left ventricular dysfunction. PMID:25548631

Yong, Celina M; Buchbinder, Maurice; Giacomini, John C

2014-01-01

182

Cavitation Inception in Spool Valves  

Microsoft Academic Search

Cavitation has been investigated in directional control valves in order to identify damage mechanisms characteristic of components of aircraft hydraulic systems. Tests have been conducted in a representative metal spool valve and in a model three times larger. Data taken under noncavitating conditions with both valves showed that the position of the high-velocity annular jet shifts orientation, depending upon valve

C. Samuel Martin; H. Medlarz; D. C. Wiggert; C. Brennen

1981-01-01

183

Engineering the Heart: Heart Valves  

NSDL National Science Digital Library

Students learn how healthy human heart valves function and the different diseases that can affect heart valves. They also learn about devices and procedures that biomedical engineers have designed to help people with damaged or diseased heart valves. Students learn about the pros and cons of different materials and how doctors choose which engineered artificial heart valves are appropriate for certain people.

Integrated Teaching And Learning Program

184

Face-Sealing Butterfly Valve  

NASA Technical Reports Server (NTRS)

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.

Tervo, John N.

1992-01-01

185

The Relationship of On-the-Job, Off-the-Job, and Refresher Training to Human Resource Outcomes and Variables.  

ERIC Educational Resources Information Center

A study of 678 unskilled and semiskilled workers found that (1) those receiving on-the-job training were paid less and had less seniority; (2) those with off-the-job training (OFJT) or refresher courses had more seniority and more promotions; (3) OFJT related to lower projected longevity; and (4) educational level was related to pay. (SK)

Kovach, Kenneth A.; Cohen, Debra J.

1992-01-01

186

Aortic valve disease.  

PubMed

Aortic valve disease is common and has significant impact on prognosis and quality of life. In this educational review, we cover the pathophysiology, presentation and assessment of aortic stenosis (AS) and aortic regurgitation (AR), including the role of imaging modalities beyond echocardiography. We review current treatment strategies and emphasise the use and indications for transcatheter aortic valve implantation (TAVI) in view of recent data highlighting its emergence as a novel treatment option for patients with AS, who are unsuitable for conventional aortic valve replacement (AVR). We also describe novel surgical approaches for AR and potential future strategies for percutaneous intervention. PMID:24898790

Rayner, J; Coffey, S; Newton, J; Prendergast, B D

2014-10-01

187

Mesofluidic two stage digital valve  

DOEpatents

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

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

2013-12-31

188

Improve safety with pilot operated relief valves  

SciTech Connect

A weakness inherent in balanced bellows pressure relief valves (PRVs) that can cause premature failure can be avoided by using pilot operated PRVs as an alternative. Now better able to handle adverse service conditions, pilot operated PRVs are suitable for a wide range of gas, liquid and mixed-phase services. Traditionally, however, balanced bellows PRVs have been applied as overpressure protection for three notable reasons: a constant PRV set pressure with the presence of variable, superimposed back pressure (at the PRV outlet prior to its opening); valve stability and adequate capacity when built-up back pressure (at the PRV outlet during its relief cycle) exceeds 10%; and spring and guided parts barriered from the process fluid. With these benefits in mind, balanced bellows PRVs have been generally adapted by many hydrocarbon processing companies that have experienced costly, and often dangerous, premature bellows failures. Corrosion, valve instability and/or bellows flutter are causes of these failures.

Emerson, G. [Anderson, Greenwood and Co., Stafford, TX (United States)

1996-10-01

189

Valve Repair or Replacement  

MedlinePLUS

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

190

Mitral Valve Prolapse  

MedlinePLUS

... CUSS-pid) valve. With each heartbeat, the atria contract and push blood into the ventricles. The flaps ... open to let blood through. Then, the ventricles contract to pump the blood out of the heart. ...

191

Mitral Valve Regurgitation  

MedlinePLUS

... Accessed Dec. 9, 2014. Rehfeldt KH, et al. Robot-assisted mitral valve repair. Journal of Cardiothoracic and Vascular Anesthesia. 2011;25:721. Suri RM, et al. Minimally invasive heart surgery: How and why in 2012. Current Cardiology Reports. ...

192

Experiences with Butterfly Valves  

Microsoft Academic Search

More than twenty years' study concerning the use of rubber-seated butterfly valves is discussed in this article. Experience has revealed an understanding of early failures and led to present favorable acceptance.

J. R. Popalisky

1974-01-01

193

Surgical double valve replacement after transcatheter aortic valve implantation and interventional mitral valve repair  

PubMed Central

Transcatheter aortic valve implantation, as well as interventional mitral valve repair, offer reasonable therapeutic options for high-risk surgical patients. We report a rare case of early post-interventional aortic valve prosthesis migration to the left ventricular outflow tract, with paravalvular leakage and causing severe mitral valve regurgitation. Initial successful interventional mitral valve repair using a clipped edge-to-edge technique revealed, in a subsequent procedure, the recurrence of mitral valve regurgitation leading to progressive heart failure and necessitating subsequent surgical aortic and mitral valve replacement. PMID:23864579

Wendeborn, Jens; Donndorf, Peter; Westphal, Bernd; Steinhoff, Gustav

2013-01-01

194

Flow control valve  

Microsoft Academic Search

This patent describes a flow-metering pressure-relief valve assembly for vehicle fuel tanks and the like, the assembly comprising a valve housing having an interior wall configured to define a chamber, inlet opening means for admitting fuel vapor into the chamber, and outlet opening means for exhausting fuel vapor from the chamber, the interior wall providing a first flow-metering surface situated

Szlaga

1989-01-01

195

Self-compassion training modulates alpha-amylase, heart rate variability, and subjective responses to social evaluative threat in women.  

PubMed

A growing body of research has revealed that social evaluative stressors trigger biological and psychological responses that in chronic forms have been linked to aging and disease. Recent research suggests that self-compassion may protect the self from typical defensive responses to evaluation. We investigated whether brief training in self-compassion moderated biopsychological responses to the Trier Social Stress Test (TSST) in women. Compared to attention (placebo) and no-training control conditions, brief self-compassion training diminished sympathetic (salivary alpha-amylase), cardiac parasympathetic, and subjective anxiety responses, though not HPA-axis (salivary cortisol) responses to the TSST. Self-compassion training also led to greater self-compassion under threat relative to the control groups. In that social stress pervades modern life, self-compassion represents a promising approach to diminishing its potentially negative psychological and biological effects. PMID:24636501

Arch, Joanna J; Brown, Kirk Warren; Dean, Derek J; Landy, Lauren N; Brown, Kimberley D; Laudenslager, Mark L

2014-04-01

196

Amount of training, deprivation, and variability of chain length as determinants of response-velocity gradients in homogeneous chains  

Microsoft Academic Search

Tested J. Platt and P. Senkowski's model for the acquisition of homogeneous behavior chains in 2 experiments with a total of 66 naive male holtzman rats. Ss were given discrete-trials lever-press training with different chain lengths and deprivation levels. Results of exp. I indicated that with constant chain lengths, response-velocity gradients were of a generally inverted- shape. As training proceeded,

John R. Platt

1972-01-01

197

Study on Improvement of the Suction Valve in a Reciprocating Compressor for an Automotive Air-Conditioner  

NASA Astrophysics Data System (ADS)

The simplified test model of the commercial reciprocating compressor for an automotive air-conditioner, which is developed in the previous study, is used to measure the displacement of the suction valves using as train gauge and to investigate the velocity distributions of the discharge flow from the valves using PIV (Particle Image Velocimetry) technique. This paper is focused on the effects of shape of the suction valve on the vibration-reduction. First, the size of the conventional valve hole and the width of the tip of the conventional valve are changed and seven new valves are manufactured to reduce the vibration of the valve. Consequently, it is found that one of the new valves is the most effective for the vibration-reduction. Next the influence of the natural frequency on the vibration-reduction is investigated using one of the new valves by changing the material and the thickness of the valve. Finally, the reason of the vibration-reduction for one of the new valves is discussed from the results of the flow analysis around the valve. The vibration-reduction for one of the new valves is confirmed by measurement of the displacement of the valve in the reciprocating compressor for the automotive air-conditioner.

Koyabu, Eitaro; Tsukiji, Tetsuhiro; Matsumura, Yoshito; Sato, Taizo

198

Actuator-valve interface optimization  

SciTech Connect

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

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

1986-01-01

199

The natural course of bicuspid aortic valve in athletes.  

PubMed

The purpose of this study was to evaluate the impact of a long-term athletic training on the clinical course of bicuspid aortic valve. A group of 81 athletes (73 M, 8 F, 22.7 +/- 5.6 years) with bicuspid aortic valve was collected. Based on clinical and echocardiographic criteria, athletes were initially divided into 2 groups: the low-risk (51 athletes) and the high-risk group (30 athletes). The high-risk athletes were disqualified from training and competitions after the first evaluation. Over the follow-up period, all of them showed significant worsening of morphologic and hemodynamic features of bicuspid aortic valve; two underwent surgical valvular repair and one of them died suddenly. Over the same period, six of the initially low-risk athletes (7%) showed significant worsening of morphologic features of bicuspid aortic valve and/or incidence of symptoms which led to their disqualification from competition. At the end of follow-up, we observed that in high-risk subjects the progression of valvular disease occurred independently from the former athletic activity and that the majority of athletes with mild bicuspid aortic valve had a benign clinical course. However, athletes with bicuspid aortic valve should be viewed with caution, and continued clinical surveillance would be mandatory. PMID:17990219

Spataro, A; Pelliccia, A; Rizzo, M; Biffi, A; Masazza, G; Pigozzi, F

2008-01-01

200

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

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

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

201

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

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

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

202

Fast closing valve  

DOEpatents

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

Hanson, Clark L. (Livermore, CA)

1984-01-10

203

Check valves aging assessment  

SciTech Connect

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

Haynes, H.D.

1991-01-01

204

Well valve control system  

SciTech Connect

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

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

1987-01-13

205

Magnetostrictive valve assembly  

NASA Technical Reports Server (NTRS)

A magnetostrictive valve assembly includes a housing that defines a passage with a seat being formed therein. A magnetically-biased and axially-compressed magnetostrictive assembly slidingly fitted in the passage is configured as a hollow and open-ended conduit adapted to support a flow of a fluid therethrough. Current-carrying coil(s) disposed about the passage in the region of the magnetostrictive assembly generate a magnetic field in the passage when current flows through the coil(s). A hollow valve body with side ports is coupled on one end thereof to an axial end of the magnetostrictive assembly. The other end of the valve body is designed to seal with the seat formed in the housing's passage when brought into contact therewith.

Richard, James A. (Inventor)

2008-01-01

206

Options for Heart Valve Replacement  

MedlinePLUS

... the mitral valve allows oxygenated blood to flow backwards into the lungs instead of continuing through the ... may be right for you? Walk through a step-by-step interactive guide explaining your valve issue ...

207

Locking apparatus for gate valves  

DOEpatents

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

Fabyan, Joseph (Livermore, CA); Williams, Carl W. (Manteca, CA)

1988-01-01

208

Virtual Airport Simulation Technology: Perceptions of Airport Operations Initial Training Program Variables and Effectiveness for Airside Professional Competence  

ERIC Educational Resources Information Center

Air travel is expected to grow by a factor of 2 to 3 times by 2025 and people working in the aviation system, including airport personnel, pilots, and air traffic controllers, must be able to safely and efficiently operate in this arena ("NextGen"). In response to the personnel training and education requirements concomitant with "NextGen,"…

DeCarlo, Jeffrey

2010-01-01

209

The Relationship among Counselor Demographic, Training, and Employment Variables and Self-Reported Multicultural and Gerontological Counseling Competence  

ERIC Educational Resources Information Center

As the "Baby Boom" population ages, the geriatric population will grow to be the largest cohort in history. Elders are considered to be members of a diverse population and, therefore, topics related to older adulthood should be addressed within multicultural training. The purpose of this study was to understand the relationship among counselor…

McBride, Rebecca G.

2010-01-01

210

Smart valves open window to process  

SciTech Connect

Technology is driving the development of smart valve-mounted field devices and emerging fieldbus protocols. These devices will be able to perform advanced functions, which are not possible with traditional analog products. The communicating digital valve controller (DVC) will also store in memory detailed maintenance and identification information. Today`s analog field instrumentation provides very little information to the distributed control system (DCS) or the business systems that reside above the DCS. Essentially the only information the operator receives is contained in one variable, the process variable. Traditional final control systems are unable to provide operators with direct information. Implied valve position (IVP) and feedback of the process variable from the transmitter are the only information available. All other information about the process or the process connected devices must be determined from the process transmitter, directly or inferred. In this digital age, one variable of information is unacceptable because it will not be enough for users to maintain a competitive edge. Initially, users required smart final control systems to be compatible with 4-20 mA systems. This remains extremely important not only for existing installations, but also for maintenance and replacement markets. In new projects or major plant expansions where a new DCS is being installed, this requirement is not as important as integration with the DCS. Users also required that smart final controls operate on installed wiring. This means that communications and power for smart field equipment must continue to share the same pair of wires. It is critical that these digital devices control the valve position with the same speed and improved positioning accuracy. Furthermore, users wanted them in intrinsically safe or explosion-proof installations. High reliability is another requirement that is not open to compromise. 2 figs.

Grumstrup, B. [Fisher Controls International, Marshalltown, IA (United States)

1995-01-01

211

Flow characteristics and performance evaluation of butterfly valves using numerical analysis  

NASA Astrophysics Data System (ADS)

The industrial butterfly valves have been applied to various fields that transport fluid in volume, especially water supply and drainage pipeline for flow control. The butterfly valves in various shapes are manufactured, but a fitting performance comparison is not made up. For this reason, we carried out numerical analysis of some kind of butterfly valves for water supply and drainage pipeline using commercial CFD code FLUENT, and made a comparative study of these results. Also, the flow coefficient, the loss coefficient, and pressure distribution of valves according to valve opening rate were compared each other and the influence of these design variables on valve performance were checked over. Through flow around the valve disk, such as pressure distribution, flow pattern, velocity vectors, and form of vortex, we grasped flow characteristics.

Jeon, S. Y.; Yoon, J. Y.; Shin, M. S.

2010-08-01

212

Acoustic and ultrasonic signals as diagnostic tools for check valves  

SciTech Connect

A typical nuclear plant has between 60 and 115 safety-related check valves ranging from 2 to 30 in. The majority of these valves control water flow. Recent studies done by the Institute of Nuclear Power Operations (INPO), Electric Power Research Institute (EPRI) and the US Nuclear Regulatory Commission (NRC) found that many of these safety-related valves were not functioning properly. Typical problems found in these valves included disk flutter, backstop tapping, flow leakage, disk pin and hinge pin wear, or even missing disks. These findings led to INPO's Significant Operating Experience Report (SOER, 1986), and finally, NRC generic letter 8904, which requires that all safety-related check valves in a nuclear plant be regularly monitored. In response to this need, the industry has developed various diagnostic equipment to monitor and test check valves, using technologies ranging from acoustics and ultrasonics to magnetic - even radiography has been considered. Of these, systems that depend on a combination of acoustic and ultrasonic techniques are among the most promising for two reasons: these two technologies supplement each other, making diagnosis of the check valves much more certain than any single technology, and this approach can be made nonintrusive. The nonintrusive feature allows the check valves to be monitored and diagnosed without being disassembled or removed from the piping system. This paper shows that by carefully studying the acoustic and ultrasonic signatures acquired from a check value, either individually or in combination, an individual with the proper training and experience in acoustic and ultrasonic signature analyses can deduce the structural integrity of the check valve with good confidence. Most of the conclusions are derived from controlled experiments in the laboratory where the diagnosis can be verified. Other conclusions were based on test data obtained in the field.

Auyang, M.K. (B and W Nuclear Technologies, Lynchburg, VA (United States))

1993-05-01

213

Valve stem and packing assembly  

DOEpatents

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

Wordin, J.J.

1991-09-03

214

Valve stem and packing assembly  

DOEpatents

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

Wordin, John J. (Bingham County, ID)

1991-01-01

215

Converter valves for HVDC applications  

Microsoft Academic Search

The performance requirements, cost, ease of installation, reliability, and temperature control of mercury arc valves and thyristor valves for HVDC applications are discussed and compared. Thyristor valves are now exclusively offered for new hvdc applications by all major suppliers. The choice of cooling medium, i.e., air, de-ionized water, oil (or possibly Freon in the future) must be made on considerations

1978-01-01

216

Piloted wellhead flow control valve  

Microsoft Academic Search

This patent describes a pilot operated flow control valve comprising: a valve body defining an operating chamber extending through the body and a flow inlet passage intersecting the operating chamber; a flow outlet member defining a discharge outlet passage connected to the valve body with the outlet passage in alignment with the operating chamber; hydraulic linear actuator means connected to

Etheridge

1987-01-01

217

Improved bellows sealed plug valve  

SciTech Connect

It is an object of the present invention to provide a bellows sealed 1/4 turn valve wherein means are provided for translating linear motion to rotational motion between the bellows seal and the valve body. This paper details the features of the valve. 6 figs.

Dukas, S.J. Jr.

1989-10-29

218

Lightweight Valve Closes Duct Quickly  

NASA Technical Reports Server (NTRS)

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

Fournier, Walter L.; Burgy, N. Frank

1991-01-01

219

Re-do mitral valve replacement using the valve-on-valve technique: a case report.  

PubMed

We report a repeated mitral valve replacement (re-do MVR) using the valve-on-valve technique for a degenerated bioprosthesis. A 49-year-old female, who had had a 29 mm Carpentier-Edwards mitral bioprosthesis for mitral regurgitation 20 years previously, was referred to our institution for dyspnea. She presented with pulmonary edema secondary to severe mitral bioprosthetic valve regurgitation. We replaced the degenerated mitral bioprosthesis with a 25 mm mechanical prosthesis using the valve-on-valve technique, as the struts of the bioprosthesis were embedded in the left ventricular myocardium. Removal of the bioprosthesis may be not only time-consuming but also complicated by cardiac rupture at the atrioventricular junction or the posterior left ventricular wall. The valve-on-valve technique is a simplified procedure that can avoid the potential complications of complete excision of the bioprosthesis. We believe this technique can be a useful strategy for patients with a degenerated mitral bioprosthesis. PMID:15900246

Tamura, Yamato; Kawata, Tetsuji; Kameda, Yoichi; Taniguchi, Shigeki

2005-04-01

220

Diversity training for signal transduction: leveraging cell-to-cell variability to dissect cellular signaling, differentiation and death  

PubMed Central

Populations of “identical” cells are rarely truly identical. Even when in the same state of differentiation, isogenic cells may vary in expression of key signaling regulators, activate signal transduction at different thresholds, and consequently respond heterogeneously to a given stimulus. Here, we review how new experimental and analytical techniques are suited to connect these different levels of variability, quantitatively mapping the effects of cell-to-cell variability on cellular decision-making. In particular, we summarize how this helps classify signaling regulators according to the impact of their variability on biological functions. We further discuss how variability can also be leveraged to shed light on the molecular mechanisms regulating cellular signaling, from the individual cell to the population of cells as a whole. PMID:23747193

Cotari, Jesse W.; Voisinne, Guillaume; Altan-Bonnet, Grégoire

2013-01-01

221

Do PTK2 gene polymorphisms contribute to the interindividual variability in muscle strength and the response to resistance training? A preliminary report.  

PubMed

The protein tyrosine kinase-2 (PTK2) gene encodes focal adhesion kinase, a structural protein involved in lateral transmission of muscle fiber force. We investigated whether single-nucleotide polymorphisms (SNPs) of the PTK2 gene were associated with various indexes of human skeletal muscle strength and the interindividual variability in the strength responses to resistance training. We determined unilateral knee extension single repetition maximum (1-RM), maximum isometric voluntary contraction (MVC) knee joint torque, and quadriceps femoris muscle specific force (maximum force per unit physiological cross-sectional area) before and after 9 wk of knee extension resistance training in 51 untrained young men. All participants were genotyped for the PTK2 intronic rs7843014 A/C and 3'-untranslated region (UTR) rs7460 A/T SNPs. There were no genotype associations with baseline measures or posttraining changes in 1-RM or MVC. Although the training-induced increase in specific force was similar for all PTK2 genotypes, baseline specific force was higher in PTK2 rs7843014 AA and rs7460 TT homozygotes than in the respective rs7843014 C- (P = 0.016) and rs7460 A-allele (P = 0.009) carriers. These associations between muscle specific force and PTK2 SNPs suggest that interindividual differences exist in the way force is transmitted from the muscle fibers to the tendon. Therefore, our results demonstrate for the first time the impact of genetic variation on the intrinsic strength of human skeletal muscle. PMID:22323655

Erskine, Robert M; Williams, Alun G; Jones, David A; Stewart, Claire E; Degens, Hans

2012-04-01

222

Redo Mitral Valve Replacement Using the Valve-on-valve Technique: A Case Report  

Microsoft Academic Search

We report a repeated mitral valve replacement (re-do MVR) using the valve-on-valve technique for a degenerated bioprosthesis. A 49-year-old female, who had had a 29 mm Carpentier-Edwards mitral bioprosthesis for mitral regurgitation 20 years previously, was referred to our institution for dyspnea. She presented with pulmonary edema secondary to severe mitral bioprosthetic valve regurgitation. We replaced the degenerated mitral bioprosthesis

Yamato Tamura; Tetsuji Kawata; Yoichi Kameda

223

Advanced thyristor valve project  

Microsoft Academic Search

General Electrics's thyristor valve project incorporates the most advanced technologies available. With joint funding from the Electric Power Research Institute, commercial application of the separate light-triggered thyristor is now underway. The cesium vapor lamp source to trigger the light sensitive thyristors will reduce component complexity and cost. A unique thermal management feature relies on forced vaporization cooling with Freon-113, which

Damsky

1984-01-01

224

Model Heart Valves  

NSDL National Science Digital Library

Students use provided materials to design and build prototype artificial heart valves. Their functioning is demonstrated using water to simulate the flow of blood through the heart. Upon completion, teams demonstrate their fully functional prototypes to the rest of the class, along with a pamphlet that describes the device and how it works.

2014-09-18

225

Mud saver valve  

Microsoft Academic Search

This patent describes a mud saver valve for retaining drilling fluid in the kelly of a rotary drilling rig. It comprises: a kelly sub defining an open-ended elongated body having threaded ends for forming a connection between the kelly and a drill pipe string; an enlarged bore formed in said elongated body; a tubular body received within said enlarged bore

Baugh

1990-01-01

226

Valve replacement in children  

Microsoft Academic Search

With increasing experience in the surgical management of children with congenital heart disease has come an increasing use of prosthetic valves. They have been employed in a wide variety of conditions ranging from simple congenital stenosis or incompetence to an essential part of repair of more complex disorders. As in adult cardiac surgery, there has been considerable debate over the

Martin J. Elliott; Marc de Leval

1985-01-01

227

Mathematical modeling of aortic valve dynamics during systole.  

PubMed

We have derived a mathematical model describing aortic valve dynamics and blood flow during systole. The model presents a realistic coupling between aortic valve dynamics, sinus vortex local pressure, and variations in the systemic vascular resistance. The coupling is introduced by using Hill?s classical semi-spherical vortex model and an aortic pressure-area compliance constitutive relationship. The effects of introducing aortic sinus eddy vortices and variable systemic vascular resistance on overall valve opening-closing dynamics, left ventricular pressure, aortic pressure, blood flow rate, and aortic orifice area are examined. In addition, the strength of the sinus vortex is coupled explicitly to the valve opening angle, and implicitly to the aortic orifice area in order to predict how vortex strength varies during the four descriptive phases of aortic valve motion (fast-opening, fully-opening, slow-closing, and fast-closing). Our results compare favorably with experimental observations and the model reproduces well-known phenomena corresponding to aortic valve function such as the dicrotic notch and retrograde flow at end systole. By invoking a more complete set of physical phenomena, this new model will enable representation of pathophysiological conditions such as aortic valve stenosis or insufficiency, making it possible to predict their integrated effects on cardiac load and systemic hemodynamics. PMID:25451522

Aboelkassem, Yasser; Savic, Dragana; Campbell, Stuart G

2015-01-21

228

Miniature Latching Valve  

NASA Technical Reports Server (NTRS)

A miniature latching valve has been invented to satisfy a need for an electrically controllable on/off pneumatic valve that is lightweight and compact and remains in the most recently commanded open or closed state when power is not supplied. The valve includes a poppet that is moved into or out of contact with a seat to effect closure or opening, respectively, of the flow path. Motion of the poppet is initiated by electrical heating of one of two opposing pairs of nickel/titanium shape-memory alloy (SMA) wires above their transition temperature: heated wires contract to their remembered length, applying tension to pull the poppet toward or away from the seat. A latch consisting mainly of a bistable Belleville washer (a conical spring) made of a hardened stainless steel operates between two stable positions corresponding to the fully closed or fully open state, holding the poppet in one of these positions when power is not applied to either pair of SMA wires. To obtain maximum actuation force and displacement, the SMA wires must be kept in tension. The mounting fixtures at the ends of the wires must support large tensile stresses without creating stress concentrations that would limit the fatigue lives of the wires. An earlier design provided for each wire to be crimped in a conical opening with a conical steel ferrule that was swaged into the opening to produce a large, uniformly distributed holding force. In a subsequent design, the conical ferrule was replaced with a larger crimped cylindrical ferrule depicted in the figure. A major problem in designing the valve was to protect the SMA wires from a bake-out temperature of 300 C. The problem was solved by incorporating the SMA wires into an actuator module that is inserted into a barrel of the valve body and is held in place by miniature clip rings.

Johnson, A. David; Benson, Glendon M.

2008-01-01

229

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

PubMed Central

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

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

2013-01-01

230

Multi-port valve assembly  

DOEpatents

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

Guggenheim, S. Frederic (Teaneck, NJ)

1986-01-01

231

Optimising BMW four-cylinder two-valve engines Optimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOptimising BMW Four-Cylinder Two-Valve Engines (OpOpt  

NASA Astrophysics Data System (ADS)

In model year 1994, BMW will present two essentially redesigned 4-cylinder, 2-valve engines. BMW has upgraded its 1.6 1 and 1.8 1 2-valve engines using technical features previously reserved for the 4-valve engines, such as knock control system, distributorless semiconductor ignition, variable induction system (DISA) and ribbed V-belt accessory drive, along with measures to reduce power losses, noise levels and exhaust emissions. BMW models equipped with these two engines offer customers improved response characteristics and fuel consumption, as well as reduced emissions and maintenance requirements.

Flierl, R.; Kramer, F.; Rech, H.; Stanski, U.; Wenzel, M.

1993-11-01

232

Cavitation detection of butterfly valve using support vector machines  

NASA Astrophysics Data System (ADS)

Butterfly valves are popularly used in service in the industrial and water works pipeline systems with large diameter because of its lightweight, simple structure and the rapidity of its manipulation. Sometimes cavitation can occur, resulting in noise, vibration and rapid deterioration of the valve trim, and do not allow further operation. Thus, monitoring of cavitation is of economic interest and is very important in industry. This paper proposes a condition monitoring scheme using statistical feature evaluation and support vector machine (SVM) to detect the cavitation conditions of butterfly valve which used as a flow control valve at the pumping stations. The stationary features of vibration signals are extracted from statistical moments. The SVMs are trained, and then classify normal and cavitation conditions of control valves. The SVMs with the reorganized feature vectors can distinguish the class of the untrained and untested data. The classification validity of this method is examined by various signals acquired from butterfly valves in the pumping stations. And the classification success rate is compared with that of self-organizing feature map neural network (SOFM).

Yang, Bo-Suk; Hwang, Won-Woo; Ko, Myung-Han; Lee, Soo-Jong

2005-10-01

233

Controlling the cavitation phenomenon of evolution on a butterfly valve  

NASA Astrophysics Data System (ADS)

Development of the phenomenon of cavitation in cavitation behavior requires knowledge of both plant and equipment working in the facility. This paper presents a diagram of cavitational behavior for a butterfly valve with a diameter of 100 mm at various openings, which was experimentally built. We proposed seven stages of evolution of the phenomenon of cavitation in the case of a butterfly valve. All these phases are characterized by pressure drop, noise and vibration at various flow rates and flow sections through the valve. The level of noise and vibration for the seven stages of development of the phenomenon of cavitation were measured simultaneously. The experimental measurements were comprised in a knowledge database used in training of a neural network of a neural flow controller that maintains flow rate constantly in the facility by changing the opening butterfly valve. A fuzzy position controller is used to access the valve open. This is the method proposed to provide operational supervision outside the cavitation for a butterfly valve.

Baran, G.; Catana, I.; Magheti, I.; Safta, C. A.; Savu, M.

2010-08-01

234

Exploring inclusion preservice training needs: a study of variables associated with attitudes and self?efficacy beliefs  

Microsoft Academic Search

The study examined attitudes towards inclusion and sense of efficacy of 1155 Israeli preservice teachers and variables related to these beliefs. Participants responded to an Options related to inclusion scale, and a Teacher efficacy scale. Findings revealed strong support for the principle of inclusion, yet also support for segregated special education placements. Several concerns regarding inclusion were expressed, which were

Shlomo Romi; Yona Leyser

2006-01-01

235

Which valve and which size should we use in the valve-on-valve technique for re-do mitral valve surgery?  

PubMed

The valve-on-valve (VOV) technique is that a mechanical valve is implanted on the sewing cuff of the previous bioprosthesis after removing degenerated leaflets. We conducted an in vitro study to determine the size-match of the valves for VOV technique. The Carpentier-Edwards pericardial (CEP) valve and Mosaic valve were used. We measured the inner diameter of the bioprosthesis after removing the leaflets. We investigated five mechanical mitral valves and two mechanical aortic valves (inverted use). The mitral valves used in this study were the ATS valve (ATS), the CarboMedics standard valve (CMS), the CarboMedics OptiForm valve (CMO), the On-X valve, and the St Jude valve (SJM). Two aortic mechanical valves, CarboMedics and St Jude Regent valves, were investigated for inverted use. After removing the tissue leaflets, the inner diameter of the Mosaic valve was 3 mm smaller than that of the CEP valve even in the same catalogue labeling size. The outer diameters of the housing of the ATS, CMS, CMO, On-X, and SJM valves of the same catalogue size (25 mm) were 25.7, 25.8, 22.0, 25.0, and 23.2 mm, respectively. SJM and CMO valves are the favorite mechanical valve for the VOV technique in terms of the profile and size-match. PMID:19010939

Shibata, Toshihiko; Inoue, Kazushige; Ikuta, Takeshi; Bito, Yasuyuki; Yoshioka, Yoshiteru; Mizoguchi, Hiroki

2009-02-01

236

Transvenous Transcatheter Valve-in-Valve Implantation after Bioprosthetic Tricuspid Valve Failure  

PubMed Central

We describe the case of a 38-year-old man with a history of metastatic testicular cancer who had undergone multiple thoracic surgical procedures, including tricuspid valve replacement with a bioprosthetic valve as a result of tricuspid involvement of his malignancy. He presented at our outpatient cardiology clinic with worsening fatigue, shortness of breath, and peripheral edema, investigation of which revealed severe tricuspid bioprosthesis stenosis with central regurgitation. Because of the patient's medical history, he was considered to be a high-risk surgical candidate. Therefore, transcatheter tricuspid valve-in-valve implantation of a 26-mm Edwards Sapien® valve was attempted through a transjugular approach. The procedure restored tricuspid valvar competence and substantially improved the patient's symptoms. We discuss the technical aspects of this case and briefly review the usefulness of the valve-in-valve technique in the tricuspid position. PMID:25425983

Reul, Ross M.; Cannizzaro, Leon; Dougherty, Kathryn G.

2014-01-01

237

Fast acting multiple element valve  

DOEpatents

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

Yang, Jefferson Y. S. (Orange, CA); Wada, James M. (Torrance, CA)

1991-01-01

238

[Prosthetic valve replacement in children].  

PubMed

Between 1975 and 1998, 27 patients aged 3 months to 14 years underwent replacement of the aortic, mitral, tricuspid, and pulmonary valves. Five different types of prosthetic valves were used; three were mechanical valves and two were bioprosthetic valves. There were 3 hospital deaths. Among the 24 survivors there were 4 late deaths. Arrhythmia requiring pacemaker implantation occurred in 2 cases after AVR and TVR. Thromboembolic events occurred in 3 patients, all with mechanical valves in pulmonary position. Infective endocarditis occurred in 1 patient after PVR with a mechanical valve. No bleeding complication occurred among the patients on a regimen of Coumadin and Dipyridamole. Two patients, both with Hancock bioprosthesis, required a second valve replacement on account of severely calcified changes. Mechanical valves in left side heart had a satisfactory long-term performance. One patient who had undergone MVR for congenital parachute mitral valve received reoperation for growth. A larger sized prosthetic valve should be used at the first replacement, and special procedures including supra-annular positioning or annular augmentation are recommended for MVR or AVR respectively. PMID:10226417

Sasahashi, N; Ando, F; Okamoto, F; Hanada, M; Yamanaka, K; Kameyama, T; Nishigaki, Y; Hirose, K; Kambara, A; Sakazaki, H; Suzuki, T; Makino, S

1999-04-01

239

[Aortic valve replacement for rheumatoid aortic valve regurgitation].  

PubMed

Valve replacement for aortic regurgitation in patient with rheumatoid arthritis was rare in Japan. We report a successful case in which aortic regurgitation necessitated aortic valve replacement. A 62-year-old woman was admitted for shortness of breath, chest pain and progressive edema. She had been treated for rheumatoid arthritis for more than ten years using steroids. The aortic valve was successfully replaced by a prosthetic mechanical valve. The histopathological examination of the excised aortic valve demonstrated rheumatic nodules in the right- and non-coronary cusp. It was supported that these changes caused shrinkage of cusp and resulted in aortic regurgitation. This patient was discharged on the 20th postoperative day. There was no evidence of detachment of the prosthetic valve. PMID:7474590

Uwabe, K; Tsuchiya, K; Hosaka, S; Morishita, A; Iida, Y; Oyama, T

1995-09-01

240

Advanced thyristor valve project  

SciTech Connect

An advanced thyristor value was developed HVDC conversion applications. New features incorporated in the design include: improved heat transfer from the thyristors, two phase cooling of components, and light firing required the development of both a separate light triggered thyristor with a full forward blocking voltage rating and a special flash lamp employing cesium vapor as the associated light source. A valve rated 133 kV and 2200 A bridge current was constructed and lab tested before shipment to the Sylmar Converter Station, which is the southern terminus of the Pacific DC Intertie. The Los Angeles Department of Water and Power, which operates the Sylmar Station, installed the valve and operated it to gain experience. 36 figs., 5 tabs.

Flairty, C. (General Electric Co., Malvern, PA (USA))

1991-04-01

241

Rotary multiposition valve  

DOEpatents

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

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

1984-04-06

242

Stemless ball valve  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

243

Percutaneous pulmonary valve replacement.  

PubMed

Percutaneous pulmonary valve implantation helps in prolonging the lifespan of surgically placed right ventricle-to-pulmonary artery (RV-PA) conduits, and represents a less invasive alternative to repeat open-heart surgery. The clinical indications for treatment match those of surgery. As far as the suitability is concerned, the current ideal substrate is a degenerated RV-PA conduit, because of the presence of a certain degree of calcification that offers a safe anchoring point. So far, patients have been treated with low morbidity and mortality that were further improved with increasing experience. After percutaneous pulmonary valve implantation, patients experience a subjective improvement, mirrored by an objective increase of measured exercise capacity parameters and by reduced RV-PA gradient, regurgitant fraction, and RV volumes. New developments in the experimental field should result in an extension of indications in the future. PMID:19322077

Frigiola, Alessandra; Nordmeyer, Johannes; Bonhoeffer, Philipp

2009-05-01

244

Percutaneous Pulmonary Valve Implantation  

PubMed Central

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

Lee, Hyoung-Doo

2012-01-01

245

Modeling and simulation of the proportional valve control system for the turbocharger  

Microsoft Academic Search

The key technology of the advanced variable nozzle turbocharger is the proportional valve control system. In this article, the fundamental dynamic equations of the proportional valve control system for the turbocharger are deduced by analyzing the principle of operation, the mathematical model of the control system is established, and the control system is simulated by using the MATLAB\\/Simulink. The static

Sheng-Guan Qu; Yi-Hua Zhang; Zi-Guo Ye; Ming Shao; Wei Xia

2010-01-01

246

Fast-acting valve and uses thereof  

DOEpatents

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

Meyer, James A. (Espanola, NM)

1982-01-01

247

Fast-acting valve and uses thereof  

DOEpatents

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

Meyer, J.A.

1980-05-16

248

Advanced thyristor valve project  

SciTech Connect

General Electrics's thyristor valve project incorporates the most advanced technologies available. With joint funding from the Electric Power Research Institute, commercial application of the separate light-triggered thyristor is now underway. The cesium vapor lamp source to trigger the light sensitive thyristors will reduce component complexity and cost. A unique thermal management feature relies on forced vaporization cooling with Freon-113, which equals the thermal performance of water without posing insulation reliability problems. 7 figures.

Damsky, B.L.

1984-01-01

249

Supramolecular spin valves.  

PubMed

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

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

2011-07-01

250

Optimal Design of a High-Speed On/Off Valve for a Hydraulic Hybrid Vehicle Application  

E-print Network

techniques to the valve design. The results of this optimization are presented for a Virtually Variable Displacement Pump, and a Virtually Variable Displacement Pump/motor, which is used as the wheel motor nspool Spool Diameter Exponent 2.75 same none Pr Relief Valve Pressure N/A 228 bar ln Inlet Nozzle Length

Li, Perry Y.

251

Actuator-valve interface optimization. [Explosive actuators  

SciTech Connect

The interface of explosive actuator driven valves can be optimized to maximize the velocity of the valve plunger by using the computer code Actuator-Valve Response. Details of the AVR model of the actuator driven valve plunger and the results of optimizing an actuator-valve interface with AVR are presented. 5 refs., 5 figs., 3 tabs.

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

1987-02-01

252

Valve operating system for internal combustion engine  

Microsoft Academic Search

This patent describes a valve operating system for an internal combustion engine, comprising an intake rotary valve and an exhaust rotary valve separately disposed in an intake passage and an exhaust passage, respectively, which independently communicate with a combustion chamber defined between a piston and a cylinder head in an internal combustion engine, the valves including spherical valve bodies adapted

M. Matsuura; M. Nakamori; M. Kuroki

1988-01-01

253

Performance Characteristics of an Isothermal Freeze Valve  

SciTech Connect

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.

Hailey, A.E.

2001-08-22

254

Update of transcatheter valve treatment  

PubMed Central

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. PMID:23897785

Liu, Xian-bao; Wang, Jian-an

2013-01-01

255

Streamline coal slurry letdown valve  

DOEpatents

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

Platt, Robert J. (Dover, NJ); Shadbolt, Edward A. (Basking Ridge, NJ)

1983-01-01

256

Streamline coal slurry letdown valve  

DOEpatents

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

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

1983-11-08

257

Semi-active compressor valve  

DOEpatents

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

Brun, Klaus (Helotes, TX); Gernentz, Ryan S. (San Antonio, TX)

2010-07-27

258

Innovative Stemless Valve Eliminates Emissions  

NASA Technical Reports Server (NTRS)

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

2008-01-01

259

Mitral Valve Prolapse (For Parents)  

MedlinePLUS

... a Heart Defect Atrial Septal Defect Heart and Circulatory System Congenital Heart Defects Arrhythmias Heart Murmurs Your Heart & Circulatory System Mitral Valve Prolapse Marfan Syndrome Ventricular Septal Defect ...

260

Freeze protection valve for solar heaters  

SciTech Connect

This patent describes a solar heater freeze protection valve apparatus comprising in combination: a valve housing; a remote sensor operatively connected to the valve housing from a remote position, the remote sensor including a bulb containing a liquid adapted to compress and expand with the temperature adjacent the bulb; a piston located in the valve body and slidable responsive to expansion and contraction of the liquid in the remote sensor; a first valve element located in the valve housing and attached to the valve piston for movement; a second valve element located in the valve housing and attached to the housing; a first valve seat in the second valve element forming an opening; a second valve seat positioned in a water passageway to allow the flow of fluid when the second valve element is in an open position and to cut off the flow of fluid when the second valve element is in a closed position. Liquid in a solar heater flows at predetermined temperature readings; and the second valve element is biased in one direction and has a second opening to increase the pressure therebehind when the first valve element closes on the first valve seat. The second valve element closes on the second valve seat.

Cromer, C.J.

1987-07-21

261

The effects of autogenic-feedback training on motion sickness severity and heart rate variability in astronauts  

NASA Technical Reports Server (NTRS)

Space motion sickness (SMS) affects 50 percent of all people during early days of spaceflight. This study describes the results of two Shuttle flight experiments in which autogenic-feedback training (AFT), a physiological conditioning method, was tested as a treatment for this disorder. Of the six who were designated as flight subjects (two women and four men), three were given treatment and three served as controls (i.e., no AFT). Treatment subjects were given 6 hours of preflight AFT. Preflight results showed that AFT produced a significant increase in tolerance to rotating chair motion sickness tests. Further, this increased tolerance was associated with changes in specific physiological responses and reports of reduced malaise. Flight results showed that two of the three control subjects experienced repeated vomiting on the first mission day, while one subject experienced only moderate malaise. Of the three treatment subjects, one experienced mild discomfort, one moderate discomfort, and one severe motion sickness. Only the three control subjects took medication for symptom suppression. Measures of cardiac function reflective of vagal control were shown to be affected especially strongly on the first day of space flight. AFT given for control of heart rate, respiration, and other autonomic activity influenced both the vagal control measures and SMS. These data suggest that AFT may be an effective treatment for space motion sickness; however, this cannot be demonstrated conclusively with the small number of subjects described.

Toscano, William B.; Cowings, Patricia S.

1994-01-01

262

49 CFR 192.145 - Valves.  

Code of Federal Regulations, 2010 CFR

...ratings for comparable steel valves at their listed temperature...in the fabrication of the valve shells or their assembly. (e) No valve having shell (body, bonnet...the gas pipe components of compressor stations. [35 FR...

2010-10-01

263

All metal valve structure for gas systems  

DOEpatents

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

Baker, Ray W. (Hamilton, OH); Pawlak, Donald A. (Centerville, OH); Ramey, Alford J. (Miamisburg, OH)

1984-11-13

264

IADC mud equipment manual. Handbook 10: Valves  

SciTech Connect

Contents include: Terminology, Application of valve types: gate, ball, butterfly, check, plug, safety relief, and choke. Codes of the valve industry. End connections. Safety precautions. Fittings. Automatic actuators and control consoles. Internal forces affecting operating torque and valve life expectancy.

Not Available

1985-01-01

265

Ultrathin gate valve for high vacuum operation  

NASA Technical Reports Server (NTRS)

Thin, compact, high-vacuum gate valve used to join two vacuum systems together demonstrates multiple operation reliability. Valve measurements and non-protruding handle make valve usable in confined areas.

Ugiansky, R. J.

1971-01-01

266

Gasoline-like Fuel Effects on High-load, Boosted HCCI Combustion Employing Negative Valve Overlap Strategy  

SciTech Connect

In recent years a number of studies have demonstrated that boosted operation combined with external EGR is a path forward for expanding the high load limit of homogeneous charge compression ignition (HCCI) operation with the negative valve overlap (NVO) valve strategy. However, the effects of fuel composition with this strategy have not been fully explored. In this study boosted HCCI combustion is investigated in a single-cylinder research engine equipped with direct injection (DI) fueling, cooled external exhaust gas recirculation (EGR), laboratory pressurized intake air, and a fully-variable hydraulic valve actuation (HVA) valve train. Three fuels with significant compositional differences are investigated: regular grade gasoline (RON = 90.2), 30% ethanol-gasoline blend (E30, RON = 100.3), and 24% iso-butanol-gasoline blend (IB24, RON = 96.6). Results include engine loads from 350 to 800 kPa IMEPg for all fuels at three engine speeds 1600, 2000, and 2500 rpm. All operating conditions achieved thermal efficiency (gross indicated efficiency) between 38 and 47%, low NOX emissions ( 0.1 g/kWh), and high combustion efficiency ( 96.5%). Detailed sweeps of intake manifold pressure (atmospheric to 250 kPaa), EGR (0 25% EGR), and injection timing are conducted to identify fuel-specific effects. The major finding of this study is that while significant fuel compositional differences exist, in boosted HCCI operation only minor changes in operational conditions are required to achieve comparable operation for all fuels. In boosted HCCI operation all fuels were able to achieve matched load-speed operation, whereas in conventional SI operation the fuel-specific knock differences resulted in significant differences in the operable load-speed space. Although all fuels were operable in boosted HCCI, the respective air handling requirements are also discussed, including an analysis of the demanded turbocharger efficiency.

Kalaskar, Vickey B [ORNL] [ORNL; Szybist, James P [ORNL] [ORNL; Splitter, Derek A [ORNL] [ORNL

2014-01-01

267

Minimally invasive mitral valve surgery: “The Leipzig experience”  

PubMed Central

Background Minimally invasive mitral valve surgery has become a routine procedure at our institution. The present study analyzed the early and long-term outcomes of patients undergoing minimally invasive mitral valve surgery over the last decade, with special focus on mitral valve repairs (MVRp). Methods The preoperative variables, intraoperative data and postoperative outcomes of patients undergoing minimally invasive mitral valve surgery were prospectively collected in our database from May 1999 to December 2010. The survival and freedom from reoperation were evaluated with life tables and Kaplan-Meier analyses. Results A total of 3,438 patients underwent minimally invasive mitral valve surgery, of which 2,829 were MVRps and 609 were mitral valve replacements (MVR). Forty-five patients (1.6%) required MVR due to failure of repair. The mean age was 60.3±13 years. More than a third of patients underwent concomitant procedures like tricuspid valve surgery, atrial septal defect (ASD) closure and cryoablation. The rate of conversion to sternotomy was less than 1.4%. The 30-day mortality was 0.8%. The 5- and 10-year survival of all patients (MVR and MVRp) undergoing minimally invasive mitral valve surgery was 85.7±0.6% and 71.5±1.2%, respectively. For MVRp, the survival was 87.0±0.7% and 74.2±1.4% at 5 and 10 years, respectively. Freedom from reoperation was 96.6±0.4% and 92.9±0.9% at 5 and 10 years, respectively. Conclusions Minimally invasive MVRp can be performed safely and effectively with very few perioperative complications. The early and long-term outcomes in these patients are acceptable. PMID:24349976

Seeburger, Joerg; Pfannmueller, Bettina; Garbade, Jens; Misfeld, Martin; Borger, Michael A.; Mohr, Friedrich W.

2013-01-01

268

Patents and Heart Valve Surgery - III: Percutaneous Heart Valves.  

PubMed

Advancements in technology for the treatment of valvularcardiac diseases seek to provide solutions for high risk patients in the form of percutaneous valve insertion for patients with complicated valvular disease not amenable to more traditional options. Within the last decade, cardiac valves designed for percutaneous insertion have emerged rapidly as a treatment option for valvular disease. This procedure serves as an alternative to open heart surgery, which is more invasive and requires longer ICU stay. Thus, the percutaneous valve insertion procedure has been used on older, frailer patients who are poor candidates for open heart surgery. Designs for percutaneous valve insertion systems have been in development for decades, but have only recently been approved by the FDA for use. Important considerations include stent design, valve design, balloon catheter design, and deployment method. PMID:24450590

Cheema, Faisal H; Ascha, Mona; Pervez, Mohammad Bin; Mannan, Ayesha; Kossar, Alex P; Polvani, Gianluca

2014-01-23

269

Minimally invasive transaortic mitral valve repair during aortic valve replacement.  

PubMed

Herein, we report the case of a 77-year-old man who presented with congestive heart failure. Echocardiography and cardiac catheterization revealed severe aortic stenosis with severe mitral regurgitation and a left ventricular ejection fraction of 0.20. Because of comorbidities, the patient was considered to be at high risk for double-valve surgery. In order to reduce the operative risk, a minimally invasive aortic valve replacement was performed together with a transaortic edge-to-edge repair (Alfieri stitch) of the mitral valve. We discuss the surgical technique and note the positive outcome. To our knowledge, this is the 1st report of minimally invasive aortic valve replacement and transaortic mitral valve repair with use of the Alfieri stitch. PMID:21720478

Santana, Orlando; Lamelas, Joseph

2011-01-01

270

Minimally Invasive Transaortic Mitral Valve Repair during Aortic Valve Replacement  

PubMed Central

Herein, we report the case of a 77-year-old man who presented with congestive heart failure. Echocardiography and cardiac catheterization revealed severe aortic stenosis with severe mitral regurgitation and a left ventricular ejection fraction of 0.20. Because of comorbidities, the patient was considered to be at high risk for double-valve surgery. In order to reduce the operative risk, a minimally invasive aortic valve replacement was performed together with a transaortic edge-to-edge repair (Alfieri stitch) of the mitral valve. We discuss the surgical technique and note the positive outcome. To our knowledge, this is the 1st report of minimally invasive aortic valve replacement and transaortic mitral valve repair with use of the Alfieri stitch. PMID:21720478

Santana, Orlando; Lamelas, Joseph

2011-01-01

271

A Three-dimensional Statistical Reconstruction Model of Grapevine (Vitis vinifera) Simulating Canopy Structure Variability within and between Cultivar/Training System Pairs  

PubMed Central

Background and Aims In grapevine, canopy-structure-related variations in light interception and distribution affect productivity, yield and the quality of the harvested product. A simple statistical model for reconstructing three-dimensional (3D) canopy structures for various cultivar–training system (C × T) pairs has been implemented with special attention paid to balance the time required for model parameterization and accuracy of the representations from organ to stand scales. Such an approach particularly aims at overcoming the weak integration of interplant variability using the usual direct 3D measurement methods. Model This model is original in combining a turbid-medium-like envelope enclosing the volume occupied by vine shoots with the use of discrete geometric polygons representing leaves randomly located within this volume to represent plant structure. Reconstruction rules were adapted to capture the main determinants of grapevine shoot architecture and their variability. Using a simplified set of parameters, it was possible to describe (1) the 3D path of the main shoot, (2) the volume occupied by the foliage around this path and (3) the orientation of individual leaf surfaces. Model parameterization (estimation of the probability distribution for each parameter) was carried out for eight contrasting C × T pairs. Key Results and Conclusions The parameter values obtained in each situation were consistent with our knowledge of grapevine architecture. Quantitative assessments for the generated virtual scenes were carried out at the canopy and plant scales. Light interception efficiency and local variations of light transmittance within and between experimental plots were correctly simulated for all canopies studied. The approach predicted these key ecophysiological variables significantly more accurately than the classical complete digitization method with a limited number of plants. In addition, this model accurately reproduced the characteristics of a wide range of individual digitized plants. Simulated leaf area density and the distribution of light interception among leaves were consistent with measurements. However, at the level of individual organs, the model tended to underestimate light interception. PMID:18202006

Louarn, Gaëtan; Lecoeur, Jérémie; Lebon, Eric

2008-01-01

272

Transcatheter valves: a brave New World.  

PubMed

Over the past five years, transcatheter valves have stimulated the attention of physicians, engineers, and investors. Transcatheter valve design and implantation techniques depart from the time-proven features of surgical valves, and this has an important impact on the safety and efficacy of prosthetic valve therapy. Herein is reviewed the performance of transcatheter valve procedures in comparison to surgical valves, together with a summary of the specific design features of several emerging transcatheter valves. How the current and future generation transcatheter valves are likely to impact on patient treatment is also explored. PMID:21053731

Vesely, Ivan

2010-09-01

273

Variable venturi type carburetor and associated method  

SciTech Connect

A variable venturi type carburetor is described which consists of a carburetor body provided with a suction passage therein, a slide valve supported by the body for movement across the suction passage to function as a variable venturi, a butterfly throttle valve pivotably supported by the carburetor body downstream of the slide valve, an interlocking means connecting the slide valve and the butterfly throttle valve for operation in correspondence with one another. The carburetor body comprises a side portion including a wall defining a housing recess, and a cover member fixed to the carburetor body to close the housing recess and form a housing chamber in which the interlocking means is arranged. The cover member includes an integral loosening-preventing portion, the interlocking means including a setting nut associated with the slide valve. The loosening-preventing portion engages the setting nut for preventing turning thereof, thereby to prevent the setting nut from being loosened.

Tahata, M.

1986-10-07

274

Interrelationships between different loads in resisted sprints, half-squat 1 RM and kinematic variables in trained athletes.  

PubMed

Resisted sprint running is a common training method for improving sprint-specific strength. It is well-known that an athlete's time to complete a sled-towing sprint increases linearly with increasing sled load. However, to our knowledge, the relationship between the maximum load in sled-towing sprint and the sprint time is unknown, The main purpose of this research was to analyze the relationship between the maximum load in sled-towing sprint, half-squat maximal dynamic strength and the velocity in the acceleration phase in 20-m sprint. A second aim was to compare sprint performance when athletes ran under different conditions: un-resisted and towing sleds. Twenty-one participants (17.86 ± 2.27 years; 1.77 ± 0.06 m and 69.24 ± 7.20 kg) completed a one repetition maximum test (1 RM) from a half-squat position (159.68 ± 22.61 kg) and a series of sled-towing sprints with loads of 0, 5, 10, 15, 20, 25, 30% body mass (Bm) and the maximum resisted sprint load. No significant correlation (P<0.05) was found between half-squat 1 RM and the sprint time in different loaded conditions. Conversely, significant correlations (P<0.05) were found between maximum load in resisted sprint and sprint time (20-m sprint time, r=-0.71; 5% Bm, r=-0.73; 10% Bm, r=-0.53; 15% Bm, r=-0.55; 20% Bm, r=-0.65; 25% Bm, r=-0.44; 30% Bm, r=-0.63; MaxLoad, r= 0.93). The sprinting velocity significantly decreased by 4-22% with all load increases. Stride length (SL) also decreased (17%) significantly across all resisted conditions. In addition, there were significant differences in stride frequency (SF) with loads over 15% Bm. It could be concluded that the knowledge of the individual maximal load in resisted sprint and the effects on the sprinting kinematic with different loads, could be interesting to determinate the optimal load to improve the acceleration phase at sprint running. PMID:24444204

Martínez-Valencia, María Asunción; González-Ravé, José M; Santos-García, Daniel Juárez; Alcaraz Ramón, Pedro E; Navarro-Valdivielso, Fernando

2014-01-01

275

Surge-damping vacuum valve  

DOEpatents

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

Bullock, Jack C. (Pleasanton, CA); Kelly, Benjamin E. (Tracy, CA)

1980-01-01

276

Valve-"Health"-Monitoring System  

NASA Technical Reports Server (NTRS)

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

Jensen, Scott L.; Drouant, George J.

2009-01-01

277

Rotary valve internal combustion engine  

Microsoft Academic Search

This patent describes an internal combustion engine having at least one cylinder and piston improvements therein. It comprises: a spherical rotary exhaust valve on the cylinder; means for opening and closing the exhaust valve capable of being advanced and retarded independent to the movement of the piston.

Blish

1989-01-01

278

Entake or exhaust valve actuator  

Microsoft Academic Search

Intake or exhaust valve actuator assembly is described for an internal combustion engine for hydraulically opening and closing an intake or exhaust valve for admitting intake gases from an intake conduit into a combustion chamber or permitting exhaust gases to escape from the combustion chamber into an exhaust conduit, the engine including a piston which oscillates in the combustion chamber,

Smietana

1993-01-01

279

Medications for Heart Valve Symptoms  

MedlinePLUS

... in a forward direction, rather than being forced backward through a leaky valve Additional resources: Print our medicine chart to help you keep track . Answers by Heart sheet: How do I manage my medicines ? Walk through a step-by-step interactive guide explaining your valve issue ...

280

Variable Delay Multi-Pulse Train for Fast Chemical Exchange Saturation Transfer and Relayed-Nuclear Overhauser Enhancement MRI  

PubMed Central

Purpose Chemical exchange saturation transfer (CEST) imaging is a new MRI technology allowing the detection of low concentration endogenous cellular proteins and metabolites indirectly through their exchangeable protons. A new technique, variable delay multi-pulse CEST (VDMP-CEST), is proposed to eliminate the need for recording full Z-spectra and performing asymmetry analysis to obtain CEST contrast. Methods The VDMP-CEST scheme involves acquiring images with two (or more) delays between radiofrequency saturation pulses in pulsed CEST, producing a series of CEST images sensitive to the speed of saturation transfer. Subtracting two images or fitting a time series produces CEST and relayed-nuclear Overhauser enhancement CEST maps without effects of direct water saturation and, when using low radiofrequency power, minimal magnetization transfer contrast interference. Results When applied to several model systems (bovine serum albumin, crosslinked bovine serum albumin, l-glutamic acid) and in vivo on healthy rat brain, VDMP-CEST showed sensitivity to slow to intermediate range magnetization transfer processes (rate < 100–150 Hz), such as amide proton transfer and relayed nuclear Overhauser enhancement-CEST. Images for these contrasts could be acquired in short scan times by using a single radiofrequency frequency. Conclusions VDMP-CEST provides an approach to detect CEST effect by sensitizing saturation experiments to slower exchange processes without interference of direct water saturation and without need to acquire Z-spectra and perform asymmetry analysis. PMID:23813483

Xu, Jiadi; Yadav, Nirbhay N.; Bar-Shir, Amnon; Jones, Craig K.; Chan, Kannie W. Y.; Zhang, Jiangyang; Walczak, P.; McMahon, Michael T.; van Zijl, Peter C. M.

2013-01-01

281

Automatic monitoring of valve status  

SciTech Connect

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

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

1988-01-01

282

A Parylene MEMS Electrothermal Valve  

PubMed Central

The first microelectromechanical-system normally closed electrothermal valve constructed using Parylene C is described, which enables both low power (in milliwatts) and rapid operation (in milliseconds). This low-power valve is well suited for applications in wirelessly controlled implantable drug-delivery systems. The simple design was analyzed using both theory and modeling and then characterized in benchtop experiments. Operation in air (constant current) and water (current ramping) was demonstrated. Valve-opening powers of 22 mW in air and 33 mW in water were obtained. Following integration of the valve with catheters, our valve was applied in a wirelessly operated microbolus infusion pump, and the in vivo functionality for the appropriateness of use of this pump for future brain mapping applications in small animals was demonstrated. PMID:21350679

Li, Po-Ying; Givrad, Tina K.; Holschneider, Daniel P.; Maarek, Jean-Michel I.; Meng, Ellis

2011-01-01

283

Self-Rupturing Hermetic Valve  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

284

Mitral Valve Repair for Double-orifice Mitral Valve.  

PubMed

We present an eight year-old girl who required an operation for moderate mitral insufficiency associated with partial atrioventricular septal defect. Echocardiography disclosed an ostium primum atrial septal defect and double-orifice mitral valve with moderate mitral regurgitation secondary to a cleft in the anterior leaflet and prolapse of the anterior leaflet. Intraoperative inspection revealed that the chordae from each orifice were attached to a single papillary muscle which resulted in a unique double-orifice mitral valve. Mitral valve repair using chordal shortening and cleft closure was successfully performed. Postoperative echocardiography observed trivial MR and no mitral stenosis. PMID:25194958

Duan, Qun-Jun; Gao, Zhan

2014-12-01

285

Valve for controlling solids flow  

DOEpatents

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

Feldman, David K. (Fairlawn, NJ)

1980-01-01

286

Cavitation guide for control valves  

SciTech Connect

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

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

1993-04-01

287

Prosthetic Valve Type for Patients Undergoing Aortic Valve Replacement: A Decision Analysis  

Microsoft Academic Search

Background. In two large, randomized, clinical trials long-term survival after aortic valve replacement (AVR) was similar for patients receiving tissue and mechanical aortic heart valve prostheses. Higher bleeding rates among patients with mechanical valves, who must re- ceive permanent oral anticoagulation to prevent throm- boembolism, were offset by higher reoperation rates for valve degeneration among patients with tissue valves. Because

Nancy J. O. Birkmeyer; John D. Birkmeyer; Anna N. A. Tosteson; Gary L. Grunkemeier; Charles A. S. Marrin; Gerald T. O'Connor

2010-01-01

288

The Delta Valve: a physiologic shunt system  

Microsoft Academic Search

PS Medical has advanced the state-of-the-art in hydrocephalus valve technology with the introduction of the Delta Valve. The Delta Valve is designed upon the premise that the shunted patient should have intracranial pressure (ICP) maintenance within a normal range regardless of cerebrospinal fluid (CSF) flow rate or body position. All previous valves have performance characteristics that are greatly influenced by

David A. Watson

1994-01-01

289

NONLINEAR MAGNETIC LEVITATION OF AUTOMOTIVE ENGINE VALVES  

E-print Network

, the controller is designed for and implemented on an electromagnetic valve actuator for use in automotive engines to improve performance and ro- bustness near the electromagnets. Implementation is achieved using position on an electromagnetic valve actuator for use in the actuation of automotive engine valves. 2. ELECTROMAGNETIC VALVE

Grizzle, Jessy W.

290

Heart Valve Lesson Plan Biomedical Engineering  

E-print Network

Heart Valve Lesson Plan Biomedical Engineering Objective · Introduce students to biomedical Learning Outcomes · Students will understand the role and function of heart valves. · Students will learn does a heart valve work? · Why do we need to replace heart valves? Time Required (Itemized) · Lecture

Provancher, William

291

49 CFR 192.145 - Valves.  

Code of Federal Regulations, 2012 CFR

...192.145 Valves. (a) Except for cast iron and plastic valves, each valve...contained in those requirements. (b) Each cast iron and plastic valve must comply with...and/or end flange) components made of cast iron, malleable iron, or ductile...

2012-10-01

292

49 CFR 192.145 - Valves.  

Code of Federal Regulations, 2011 CFR

...192.145 Valves. (a) Except for cast iron and plastic valves, each valve...contained in those requirements. (b) Each cast iron and plastic valve must comply with...and/or end flange) components made of cast iron, malleable iron, or ductile...

2011-10-01

293

Magnetoresistance of symmetric spin valve structures  

Microsoft Academic Search

A spin valve configuration is presented in which an unpinned ferromagnetic film is separated from exchange-pinned ferromagnetic films on either side by two nonmagnetic spacers, thereby creating a symmetric spin valve structure. The symmetric spin valve is shown to increase the magnetoresistance by 50% over the values of individual spin valves. The increase is attributed to a reduction of spin-independent

T. C. Anthony; J. A. Brug; Shufeng Zhang

1994-01-01

294

Prototype lockhopper valve testing and development  

Microsoft Academic Search

Reliable, long-life process components such as valves are essential to the success of advanced coal conversion and utilization processes. To meet part of this anticipated need, the Prototype Lockhopper Valve Development Program was created. The goal of the program was to develop valves that significantly exceed existing commercial valves by increasing temperature and pressure limits and extending service life. The

W. J. Jr. Ayers; R. A. Wojewodka

1985-01-01

295

Triple valve repair for young rheumatic patientsq  

Microsoft Academic Search

Background: Facing young foreign polyvalvular rheumatic patients, for which long-term anticoagulation is not available, we have chosen to attempt triple valve repair procedures in order to avoid prosthetic implantation in this particular population suffering from triple valve disease. Methods: Twenty-one young rheumatic patients (mean age:11 ^ 4 years) underwent triple valve repair procedures including cusp extension on the aortic valve

Jean-Michel Grinda; Christian Latremouille; Nicola D'Attellis; Alain Berrebi; Sylvain Chauvaud; Alain Carpentier; Jean-Noel Fabiani; Alain Deloche

296

Reoperation for failure of mitral valve repair  

Microsoft Academic Search

Background and Objective: Mitral valve repair is the procedure of choice to correct mitral regurgitation of all types. Up to 10% of patients who undergo mitral valvuloplasty require late reoperation for recurrent mitral valve dysfunction. To determine the causes of failed mitral valve repair, we examined the surgical pathology of patients who underwent reoperation for failed mitral valve repair. Patients

A. Marc Gillinov; Delos M. Cosgrove; Bruce W. Lytle; Paul C. Taylor; Robert W. Stewart; Patrick M. McCarthy; Nicholas G. Smedira; Derek D. Muehrcke; Carolyn Apperson-Hansen; Floyd D. Loop

1997-01-01

297

Stemless ball valve  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

298

Multi-port valve  

DOEpatents

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

Lewin, Keith F. (Calverton, NY)

1997-04-15

299

Multi-port valve  

DOEpatents

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

Lewin, K.F.

1997-04-15

300

Fluid relief and check valve  

DOEpatents

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

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

1986-07-17

301

Ferroelectric Fluid Flow Control Valve  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

302

Ischemic mitral valve prolapse: mechanisms and implications for valve repair  

Microsoft Academic Search

Objective: The aim of this study was to assess the mechanisms of prolapse in ischemic mitral valve regurgitation (MR) and the techniques of valve repair. Methods: Out of 121 patients operated upon for ischemic MR, a prolapse was present in 44 patients (36.4%). The operation was performed emergently in four cases (9.1%) and electively in 40 patients (90.9%). Fifteen patients

Jerome Jouan; Michel Tapia; Richard C. Cook; Emmanuel Lansac; Christophe Acar

2010-01-01

303

Ischemic mitral valve prolapse: mechanisms and implications for valve repair  

Microsoft Academic Search

Objective: The aim of this study was to assess the mechanisms of prolapse in ischemic mitral valve regurgitation (MR) and the techniques of valve repair. Methods: Out of 121 patients operated upon for ischemic MR, a prolapse was present in 44 patients (36.4%). The operation was performed emergently in four cases (9.1%) and electively in 40 patients (90.9%). Fifteen patients

Jérome Jouan; Michel Tapia; Richard C. Cook; Emmanuel Lansac; Christophe Acar

2004-01-01

304

Saving a Life: Heart Valve Replacement  

NSDL National Science Digital Library

Students use their knowledge about how healthy heart valves function to design, construct and implant prototype replacement mitral valves for hypothetical patients' hearts. Building on what they learned in the associated lesson about artificial heart valves, combined with the testing and scoring of their prototype heart valve designs in this activity, students discover the pros and cons of different types of artificial heart valves based on materials, surgery requirements, and lifespan.

Integrated Teaching And Learning Program

305

What Is Heart Valve Surgery?  

MedlinePLUS

... your heart are made of thin (but strong) flaps of tissue that open and close as your ... called incompetence, insufficiency or regurgitation. • Prolapse — mitral valve flaps don’t close properly (more common in women). ...

306

Mitral valve surgery - minimally invasive  

MedlinePLUS

... on your chest. The doctor sends a catheter (flexible tube) with a balloon attached on the end. The balloon inflates to stretch the opening of the valve. This procedure is called percutaneous valvuloplasty.

307

Bipropellant shut-off valve  

NASA Technical Reports Server (NTRS)

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

Smith, J. V.

1971-01-01

308

Resonant Switching Using Spin Valves  

NASA Astrophysics Data System (ADS)

Using micromagnetics we demonstrate that the r.f. field produced by a spin valve can be used to reverse the magnetization in a magnetic nanoparticle. The r.f. field is generated using a current that specifically excites a uniform spin wave in the spin valve. This current is swept such that the chirped-frequency generated by the valve matches the angular dependent resonant frequency of the anisotropy-dominated magnetic nanoparticle, as a result of which the magnetization reversal occurs. The switching is fast, requires currents similar to those used in recent experiments with spin valves, and is stable with respect to small perturbations. This phenomenon can potentially be employed in magnetic information storage devices or recently discussed magnetic computing schemes.

Rivkin, K.; Ketterson, J. B.; Saslow, W.

2007-06-01

309

Liquid-blocking check valve  

DOEpatents

A liquid blocking check valve useful particularly in a pneumatic system utilizing a pressurized liquid fill chamber. The valve includes a floatable ball disposed within a housing defining a chamber. The housing is provided with an inlet aperture disposed in the top of said chamber, and an outlet aperture disposed in the bottom of said chamber in an offset relation to said inlet aperture and in communication with a cutaway side wall section of said housing.

Merrill, J.T.

1982-09-27

310

Cross-sectional survey on minimally invasive mitral valve surgery  

PubMed Central

Background Minimally invasive mitral valve surgery (MIMVS) has become a standard technique to perform mitral valve surgery in many cardiac centers. However, there remains a question regarding when MIMVS should not be performed due to an increased surgical risk. Consequently, expert surgeons were surveyed regarding their opinions on patient factors, mitral valve pathology and surgical skills in MIMVS. Methods Surgeons experienced in MIMVS were identified through an electronic search of the literature. A link to an online survey platform was sent to all surgeons, as well as two follow-up reminders. Survey responses were then submitted to a central database and analyzed. Results The survey was completed by 20 surgeons. Overall results were not uniform with regard to contraindications to performing MIMVS. Some respondents do not consider left atrial enlargement (95% of surgeons), complexity of surgery (75%), age (70%), aortic calcification (70%), EuroSCORE (60%), left ventricular ejection fraction (55%), or obesity (50%) to be contraindication to surgery. Ninety percent of respondents believe more than 20 cases are required to gain familiarity with the procedure, while 85% believe at least one MIMVS case needs to be performed per week to maintain proficiency. Eighty percent recommend establishment of multi-institutional databases and standardized surgical mentoring courses, while 75% believe MIMVS should be incorporated into current training programs for trainees. Conclusions These results suggest that MIMVS has been accepted as a treatment option for patients with mitral valve pathologies according the expert panel. Initial training and continuing practice is recommended to maintain proficiency, as well as further research and formalization of training programs. PMID:24349974

Borger, Michael; Byrne, John G.; Chitwood, W. Randolph; Cohn, Lawrence; Galloway, Aubrey; Garbade, Jens; Glauber, Mattia; Greco, Ernesto; Hargrove, Clark W.; Holzhey, David M.; Krakor, Ralf; Loulmet, Didier; Mishra, Yugal; Modi, Paul; Murphy, Douglas; Nifong, L. Wiley; Okamoto, Kazuma; Seeburger, Joerg; Tian, David H.; Vollroth, Marcel; Yan, Tristan D.

2013-01-01

311

Abrasion resistant valves cut platform maintenance cost  

SciTech Connect

Shell Exploration and Production, operator of Brent field in the UK North Sea, turned to Anglo-US valve maker Serck Audco Valves for help in solving persistent valve maintenance problems. Brent Charlie platform was selected as a test site for the supplier`s new line of abrasion-resistant valves. The most common failure cause is abrasion by solids in the line fluid, particularly sand, which damages even stainless steel and Duplex valve seats, creating leak paths which prevent valve sealing. Serck Audco manufacturers the Super-H all-metal pressure-balanced plug valve, which has proved particularly resistant to erosion in some of the world`s harshest operating environments. The paper describes the valve`s extra abrasion resistance and the Brent Charlie test.

NONE

1997-02-01

312

Pressure control valve. [inflating flexible bladders  

NASA Technical Reports Server (NTRS)

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

Lambson, K. H. (inventor)

1980-01-01

313

Noninvasive valve monitor using alternating electromagnetic field  

DOEpatents

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

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

1993-03-16

314

Acoustic monitoring of power-plant valves  

NASA Astrophysics Data System (ADS)

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

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

1982-06-01

315

Noninvasive valve monitor using alternating electromagnetic field  

DOEpatents

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

Eissenberg, David M. (Oak Ridge, TN); Haynes, Howard D. (Knoxville, TN); Casada, Donald A. (Knoxville, TN)

1993-01-01

316

Spring-Loaded Joule-Thomson Valve  

NASA Technical Reports Server (NTRS)

Improved design reduces clogging and maintains constant pressure drop as flow rate varies. Spring-Loaded Joule-Thomson Valve pressure drop regulated by spring pushing stainless-steel ball against soft brass seat. Pressure drop remains nearly constant, regardless of helium flow rate and of any gas contaminants frozen on valve seat. Because springloaded J-T valve maintains constant pressure drop, upstream roomtemperature throttle valve adjusts flow rate precisely for any given upstream pressure. In addition, new valve relatively invulnerable to frozen gas contaminants, which clog fixed-orifice J-T valves.

Jones, J. A.; Britcliffe, M. J.

1986-01-01

317

Valve system incorporating single failure protection logic  

DOEpatents

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

Ryan, Rodger (San Jose, CA); Timmerman, Walter J. H. (Saratoga, CA)

1980-01-01

318

[Mitral valve replacement for congenital parachute mitral valve].  

PubMed

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

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

1995-07-01

319

An electromechanical valve drive incorporating a nonlinear mechanical transformer  

E-print Network

In traditional internal combustion engines, a camshaft acts on the valve stems to open and close the valves. Valve timing is fixed relative to piston position. On the other hand, if a valve is flexibly controlled by a ...

Chang, Woo Sok, 1964-

2003-01-01

320

Performance Improvement of Proportional Directional Control Valves: Methods and Experiments  

E-print Network

Performance Improvement of Proportional Directional Control Valves: Methods and Experiments Fanping slow valves (e.g. proportional directional control valves). To im- prove the performance of proportional directional control valves, three different types of controllers are synthesized. Firstly, based

Yao, Bin

321

Load Expansion of Stoichiometric HCCI Using Spark Assist and Hydraulic Valve Actuation  

Microsoft Academic Search

A spark-assist homogeneous charge compression ignition (SA-HCCI) operating strategy is presented here that allows for stoichiometric combustion from 1000-3000 rpm, and at loads as high as 750 kPa net IMEP. A single cylinder gasoline engine equipped with direct fuel injection and fully variable hydraulic valve actuation (HVA) is used for this experimental study. The HVA system enables negative valve overlap

James P Szybist; Eric J Nafziger

2010-01-01

322

The erosion-corrosion of nickel-base diesel engine exhaust valves  

Microsoft Academic Search

There are many variables that can influence the failure of nickel-base, two-cycle diesel engine exhaust valves, including engine design characteristics and operating conditions, as well as lubricant additives and resulting deposits. The entire system must be considered to understand fully the failure mechanism. However, in this preliminary investigation the emphasis was on modeling exhaust valve failure as an erosion-corrosion wear

C. G. Scott; A. T. Riga; H. Hong

1995-01-01

323

A custom-designed limited-angle actuator for an electromechanical engine valve drive Part II: Fabrication and evaluation  

E-print Network

Research has shown that variable valve timing (VVT) can improve significantly the performance of internal combustion (IC) engines, including higher fuel efficiencies, lower emissions, and larger torque outputs at each point ...

Kassakian, John G.

324

A custom-designed limited-angle actuator for an electromechanical engine valve drive Part I: Conceptual design  

E-print Network

Research has shown that variable valve timing (VVT) can improve significantly the performance of internal combustion (IC) engines, including higher fuel efficiencies, lower emissions, and larger torque outputs at each point ...

Qiu, Yihui

325

Mitral and mitro-aortic valve replacement with Sorin Bicarbon valves compared with St. Jude Medical valves  

Microsoft Academic Search

Objective: We assessed the clinical results of two bileaflet mechanical valves: the St. Jude Medical (SJM) and the Sorin Bicarbon (Sorin Bicarbon) used either in single mitral valve replacement (MVR) or in double, aortic and mitral, valve replacement (DVR).Methods: Between September 1990 and November 1995, 217 patients received either a St. Jude Medical (n=134) or a Sorin Bicarbon (n=86): 136

L. F Camilleri; P Bailly; B. J Legault; B Miguel; M.-C D'Agrosa-Boiteux; C. M de Riberolles

2001-01-01

326

Valved pulse tube refrigerator development  

NASA Astrophysics Data System (ADS)

The pulse tube refrigerator is inherently reliable since it contains no moving parts at low temperature. However, the performance of a simple pulse tube is typically lower than that of other cryocoolers both in terms of COP and temperature differential per stage. Recent work indicates that the valved pulse tube, otherwise known as the orifice pulse tube, is able to reach much lower temperatures than the simple design, 31 K having been achieved in a two stage device. The addition of the valve and buffer volume subtly alters the heat pumping mechanism in the pulse tube. The valved pulse tube is described and the nature of the heat pumping machine explained. The current status of the device is reviewed.

Richardson, R. N.

327

Propellant isolation shutoff valve program  

NASA Technical Reports Server (NTRS)

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

Merritt, F. L.

1973-01-01

328

Lost-motion valve actuator  

SciTech Connect

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

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

1987-04-07

329

Prosthetic Mitral Valve Leaflet Escape  

PubMed Central

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

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

2013-01-01

330

Non-collinear valve actuator  

NASA Technical Reports Server (NTRS)

A non-collinear valve actuator includes a primary actuating system and a return spring system with each applying forces to a linkage system in order to regulate the flow of a quarter-turn valve. The primary actuating system and return spring system are positioned non-collinearly, which simply means the primary actuating system and return spring system are not in line with each other. By positioning the primary actuating system and return spring system in this manner, the primary actuating system can undergo a larger stroke while the return spring system experiences significantly less displacement. This allows the length of the return spring to be reduced due to the minimization of displacement thereby reducing the weight of the return spring system. By allowing the primary actuating system to undergo longer strokes, the weight of the primary actuating system may also be reduced. Accordingly, the weight of the non-collinear valve actuator is reduced.

Richard, James A. (Inventor)

2012-01-01

331

Active combustion flow modulation valve  

SciTech Connect

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.

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

2013-09-24

332

Aortic Valve Injury Following Blunt Chest Trauma  

PubMed Central

Introduction: Heart valve injury following blunt chest trauma of car accidents is increasing. Although aortic valve involvement is rare, however, in survivors of blunt cardiac trauma it is the most commonly involved valve and the most frequent valve lesion is isolated injury of the noncoronary cusp of aortic valve. Case Presentation: A 31-year-old man with a history of car accident (five months before) was referred to our clinic because of shortness of breath. A holo-diastolic blowing murmur was heard on physical examination. Transesophageal echocardiography demonstrated severe aortic insufficiency secondary to rupture of the left coronary cusp associated with avulsion of aortic valve commissure. Conclusions: Since the aortic valve is rarely affected in blunt cardiac injury, it will be generally undiagnosed during the primary evaluation of a patient with blunt chest trauma. However, any patient presenting dyspnea after chest trauma should be examined for suspected aortic valve injury. PMID:25478541

Esmaeilzadeh, Maryam; Alimi, Hedieh; Maleki, Majid; Hosseini, Saeid

2014-01-01

333

Design criteria monograph for valve assemblies  

NASA Technical Reports Server (NTRS)

Monograph is limited to valve selection factors for trade-off studies, configuration analyses, actuator selection, and integration of components. Material is organized along lines of valve design sequence.

1974-01-01

334

Finite Element Analysis of the Microisolation Valve  

NASA Technical Reports Server (NTRS)

Agenda: Design and Use of the Microisolation Valve; Geometry of the Microisolation Valve; FEA Model Objectives; Results of the 10 and 50 microns Thick Wall Models; Results of the Thermally-Induced Stresses.

Man, K.; Mueller, J.; Forgrave, J.

1998-01-01

335

Transapical Transcatheter Valve-in-valve Replacement for Deteriorated Mitral Valve Bioprosthesis without Radio-Opaque Indicators: The "Invisible" Mitral Valve Bioprosthesis.  

PubMed

In view of the high number of bioprosthetic valves implanted during the past 30 years, an increasing number of patients are coming to medical attention because of degenerated bioprostheses. Transcatheter aortic valve-in-valve implantation has been described as a less invasive alternative to re-operation to treat severe structural valve deterioration. As far as degenerated mitral valve bioprostheses are concerned, transcatheter transapical mitral valve-in-valve replacement (TMVR) has been less commonly performed, but may also become a viable alternative to re-do replacement surgery. We describe treatment of a degenerated bioprosthetic mitral valve, characterised by complete absence of any radio-opaque landmarks making the TMVR procedure very challenging. PMID:25456504

Rossi, Marco Luciano; Barbaro, Cristina; Pagnotta, Paolo; Cappai, Antioco; Ornaghi, Diego; Belli, Guido; Presbitero, Patrizia

2015-02-01

336

Recurrent Ischemic Strokes in a Patient with Medtronic-Hall Prosthetic Aortic Valve and Valve Strands  

Microsoft Academic Search

Fine strands associated with prosthetic heart valves have been demonstrated with transesophageal echocardiography, but the pathologic identity of these strands is unclear. A case of a man with a prosthetic aortic Medtronic-Hall valve with prominent valve strands and recurrent strokes is discussed. The patient underwent valve replacement surgery, and histopathologic examination of the strands identified them as Lambl's excrescences. (J

Kendra Hutchinson; Faizain Hafeez; Timothy D Woods; Paramjeet S Chopra; Thomas F Warner; Ross L Levine; Timothy J Kamp

1998-01-01

337

Regression of left ventricular hypertrophy after aortic valve replacement for aortic stenosis with different valve substitutes  

Microsoft Academic Search

Objective: Stentless biologic aortic valves are less obstructive than stented biologic or mechanical valves. Their superior hemodynamic performances are expected to reflect in better regression of left ventricular hypertrophy. We compared the regression of left ventricular hypertrophy in 3 groups of patients undergoing aortic valve replacement for severe aortic stenosis. Group I (10 patients) received stentless biologic aortic valves, group

Ruggero De Paulis; Luigi Sommariva; Luisa Colagrande; Giovanni Maria De Matteis; Simona Fratini; Fabrizio Tomai; Carlo Bassano; Alfonso Penta de Peppo; Luigi Chiariello

1998-01-01

338

Optimization of multi-valve, four cycle engine design - The benefit of five-valve technology  

Microsoft Academic Search

The multi-valve four stroke cycle engine design trend is toward increased engine power and higher fuel efficiency. While a four-valve system is the most common direction, problems occur when the valve area is widened by increasing the cylinder bore for a higher engine output. The layout for four larger valves causes the combustion chamber shape to flatten and the combustion

K. Aoi; K. Nomura; H. Matsuzaka

1986-01-01

339

5. DIABLO DAM: DETAIL VIEW OF RELIEF VALVES AT ELEVATION ...  

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

5. DIABLO DAM: DETAIL VIEW OF RELIEF VALVES AT ELEVATION 1044. VALVE IN FOREGROUND IS A BUTTERFLY VALVE SIX FEET IN DIAMETER; VALVE TO THE REAR IS A JOHNSON-TYPE NEEDLE VALVE BOTH VALVES WERE MANUFACTURED BY THE PELTON WATER WHEEL COMPANY, 1989. - Skagit Power Development, Diablo Dam, On Skagit River, 6.9 miles upstream from Newhalem, Newhalem, Whatcom County, WA

340

Coolant-Control Valves For Fluid-Sampling Probes  

NASA Technical Reports Server (NTRS)

Small built-in leaks prevent overheating. Downstream flow-control globe valve replaced with modified gate valve. Modification consists of drilling small hole through valve gate, so valve never turned completely off. This "leaky" valve provides enough flow of coolant to prevent overheating causing probe to fail. Principle also applied to automatic control system by installing small bypass line around control valve.

Schultz, Donald F.

1989-01-01

341

Mechanics of the mitral valve  

PubMed Central

Alterations in mitral valve mechanics are classical indicators of valvular heart disease, such as mitral valve prolapse, mitral regurgitation, and mitral stenosis. Computational modeling is a powerful technique to quantify these alterations, to explore mitral valve physiology and pathology, and to classify the impact of novel treatment strategies. The selection of the appropriate constitutive model and the choice of its material parameters are paramount to the success of these models. However, the in vivo parameters values for these models are unknown. Here we identify the in vivo material parameters for three common hyperelastic models for mitral valve tissue, an isotropic one and two anisotropic ones, using an inverse finite element approach. We demonstrate that the two anisotropic models provide an excellent fit to the in vivo data, with local displacement errors in the sub-millimeter range. In a complementary sensitivity analysis, we show that the identified parameter values are highly sensitive to prestrain, with some parameters varying up to four orders of magnitude. For the coupled anisotropic model, the stiffness varied from 119,021kPa at 0% prestrain via 36kPa at 30% prestrain to 9kPa at 60% prestrain. These results may, at least in part, explain the discrepancy between previously reported ex vivo and in vivo measurements of mitral leaflet stiffness. We believe that our study provides valuable guidelines for modeling mitral valve mechanics, selecting appropriate constitutive models, and choosing physiologically meaningful parameter values. Future studies will be necessary to experimentally and computationally investigate prestrain, to verify its existence, to quantify its magnitude, and to clarify its role in mitral valve mechanics. PMID:23263365

Rausch, Manuel K.; Famaey, Nele; Shultz, Tyler O’Brien; Bothe, Wolfgang; Miller, D. Craig

2013-01-01

342

Aortic valve replacement in systemic sclerosis.  

PubMed

Systemic sclerosis (scleroderma) is a chronic systemic autoimmune disease of the connective tissue, which can involve the cardiac valves, the mitral valve being more frequently affected, although involvement of the aortic valve has been rarely described. We report a patient with aortic stenosis and systemic sclerosis who required aortic valve replacement. Awareness of this rare association may help to provide adequate management of such patients and prevent complications related to the underlying disease. PMID:24625565

Ferrari, Gabriele; Pratali, Stefano; Pucci, Angela; Bortolotti, Uberto

2015-01-01

343

Triple valve repair for young rheumatic patients  

Microsoft Academic Search

Background: Facing young foreign polyvalvular rheumatic patients, for which long-term anticoagulation is not available, we have chosen to attempt triple valve repair procedures in order to avoid prosthetic implantation in this particular population suffering from triple valve disease. Methods: Twenty-one young rheumatic patients (mean age:11±4 years) underwent triple valve repair procedures including cusp extension on the aortic valve aortic between

Jean-Michel Grinda; Christian Latremouille; Nicola D'Attellis; Alain Berrebi; Sylvain Chauvaud; Alain Carpentier; Jean-Noël Fabiani; Alain Deloche

2002-01-01

344

Design and development of a large diameter high pressure fast acting propulsion valve and valve actuator  

NASA Technical Reports Server (NTRS)

The design and development of a large diameter high pressure quick acting propulsion valve and valve actuator is described. The valve is the heart of a major test facility dedicated to conducting full scale performance tests of aircraft landing systems. The valve opens in less than 300 milliseconds releasing a 46-centimeter- (18-in.-) diameter water jet and closes in 300 milliseconds. The four main components of the valve, i.e., valve body, safety shutter, high speed shutter, and pneumatic-hydraulic actuator, are discussed. This valve is unique and may have other aerospace and industrial applications.

Srinivasan, K. V.

1986-01-01

345

Fast-acting valve actuator  

DOEpatents

A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

Cho, Nakwon (Knoxville, TN)

1980-01-01

346

Low pressure piezoelectric valve design  

NASA Astrophysics Data System (ADS)

In this paper a ball-type valve actuated by a piezoelectric bender is studied. In this valve different parameters are adjustable allowing different operational aspects. The design procedure is economic and easy to test. Some models are developed to allow an optimization of the structure for special requirements. A prototype has been manufactured to verify the models. The measurement procedure is exposed. This design does not allow high tank pressure but, on this basis, a structure where the pressure locks the ball (reverse structure) is possible.

Bernard, Y.; Razek, A.

2012-06-01

347

Analysis of aortic valve commissural fusion after support with continuous-flow left ventricular assist device  

PubMed Central

OBJECTIVES Continuous-flow left ventricular assist devices (cf-LVADs) may induce commissural fusion of the aortic valve leaflets. Factors associated with this occurrence of commissural fusion are unknown. The aim of this study was to examine histological characteristics of cf-LVAD-induced commissural fusion in relation to clinical variables. METHODS Gross and histopathological examinations were performed on 19 hearts from patients supported by either HeartMate II (n = 17) or HeartWare (n = 2) cf-LVADs and related to clinical characteristics (14 heart transplantation, 5 autopsy). RESULTS Eleven of the 19 (58%) aortic valves showed fusion of single or multiple commissures (total fusion length 11 mm [4–20] (median [interquartile range]) per valve), some leading to noticeable nodular displacements or considerable lumen diameter narrowing. Multiple fenestrations were observed in one valve. Histopathological examination confirmed commissural fusion, with varying changes in valve layer structure without evidence of inflammatory infiltration at the site of fusion. Commissural fusion was associated with continuous aortic valve closure during cf-LVAD support (P = 0.03). LVAD-induced aortic valve insufficiency developed in all patients with commissural fusion and in 67% of patients without fusion. Age, duration of cf-LVAD support and aetiology of heart failure (ischaemic vs dilated cardiomyopathy) were not associated with the degree of fusion. CONCLUSIONS Aortic valve commissural fusion after support with cf-LVADs is a non-inflammatory process leading to changes in valve layer structure that can be observed in >50% of cf-LVAD patients. This is the first study showing that patients receiving full cf-LVAD support without opening of the valve have a significantly higher risk of developing commissural fusion than patients on partial support. PMID:23798641

Martina, Jerson R.; Schipper, Marguerite E.I.; de Jonge, Nicolaas; Ramjankhan, Faiz; de Weger, Roel A.; Lahpor, Jaap R.; Vink, Aryan

2013-01-01

348

Spin valve and dual spin valve heads with synthetic antiferromagnets  

Microsoft Academic Search

Analytical and micromagnetic analysis have been performed for synthetic antiferromagnet (SAF) biased single and dual spin valve heads. It is found that for a un-pinned SAF under an external field, the antiparallel axis will flop to the direction orthogonal to the field direction. Introducing a thickness differential in the SAF can help to prevent the magnetization flop in addition to

Jian-Gang Zhu

1999-01-01

349

Control Valves: International Site for Spirax Sarco  

NSDL National Science Digital Library

This website contains a series of tutorials about flow control valve topics. The topics include capacity, sizing, valve types, characteristics, actuators, positioners, controllers and sensors. The website is broken down into five different sections covering everything from simply control valves themselves to the sensors which help to control these systems.

2008-11-04

350

The thyristor valve in HVDC transmission  

Microsoft Academic Search

The application of thyristor valves rather than mercury-arc valves for ; rectification in high-voltage dc transmission systems has increased. Schemes in ; service include Eel River in New Brunswick, Canada, the Gotland extension in ; Sweden, and the Sakuma extension in Japan. Basic circuits, design, construction, ; and operation methods are discussed for the use of thyristor valves in HVDC

G. Karady; T. Gilsig

1973-01-01

351

Loss determination of HVDC thyristor valves  

SciTech Connect

Losses in HVDC thyristor valves are an important economic factor, but their verification by direct electrical measurement is not practical. The origin and method of dissipation of valve losses is described and alternative methods for valve loss verification are reviewed. The most economic and reliable method appears to be the summation of calculated component losses.

Lips, H.P.

1986-01-01

352

Echocardiographic assessment of prosthetic heart valves.  

PubMed

Valvular heart disease is a global health problem. It is estimated that more than 280,000 prosthetic heart valves are implanted worldwide each year. As the world's population is aging, the incidence of prosthetic heart valve implantation and the prevalence of prosthetic heart valves continue to increase. Assessing heart valve prosthesis function remains challenging, as prosthesis malfunction is unpredictable but not uncommon. Transthoracic two-dimensional and Doppler echocardiography is the preferred method for assessing prosthetic valve function. Clinically useful Doppler-derived measures for assessing prosthetic valve hemodynamic profiles have been reported for aortic, mitral, and tricuspid valve prostheses, but echocardiographic data regarding pulmonary valve prostheses remain limited. Complete prosthetic valve evaluation by transthoracic echocardiography (TTE) is sometimes challenging due to acoustic shadowing and artifacts. In these cases, further imaging with transesophageal echocardiography, fluoroscopy and/or gated CT may be warranted, particularly if prosthetic valve dysfunction is suspected. Being able to differentiate pathologic versus functional obstruction of an individual prosthesis is extremely important, as this distinction affects management decisions. Transprosthetic and periprosthetic regurgitation may be difficult to visualize on TTE, so careful review of Doppler-derived data combined with a high index of suspicion is warranted, particularly in symptomatic patients. A baseline TTE soon after valve implantation is indicated in order to "fingerprint" the prosthesis hemodynamic profile. It remains unclear how frequently serial imaging should be performed in order to assess prosthetic valve function, as this issue has not been systematically studied. PMID:25081405

Blauwet, Lori A; Miller, Fletcher A

2014-01-01

353

Design criteria monograph for valve components  

NASA Technical Reports Server (NTRS)

Monograph treats valve design technology problems as they were solved in successful development of flightweight operational valves for liquid rocket systems. General practices for cleaning and contamination prevention are summarized. Balance of information is arranged by topic, since detail design requirements apply to most types of valves.

1974-01-01

354

Valve for fuel pin loading system  

DOEpatents

A cyclone valve surrounds a wall opening through which cladding is projected. An axial valve inlet surrounds the cladding. Air is drawn through the inlet by a cyclone stream within the valve. An inflatable seal is included to physically engage a fuel pin subassembly during loading of fuel pellets.

Christiansen, David W. (Kennewick, WA)

1985-01-01

355

CONTROL VALVE TESTING PROCEDURES AND EQUATIONS  

E-print Network

diameters Section A.1. Flow Coefficients Definition The flow coefficient or pressure loss coefficient is used to relate the pressure loss of a valve to the discharge of the valve at a given valve opening. The most widely used flow coefficient is Cv of equation A1, where Q is in gpm, Pnet is the net pressure

Rahmeyer, William J.

356

Valve for fuel pin loading system  

DOEpatents

A cyclone valve surrounds a wall opening through which cladding is projected. An axial valve inlet surrounds the cladding. Air is drawn through the inlet by a cyclone stream within the valve. An inflatable seal is included to physically engage a fuel pin subassembly during loading of fuel pellets.

Christiansen, D.W.

1984-01-01

357

Valves Based on Amplified Piezoelectric Actuators  

Microsoft Academic Search

Amplified Piezo Actuators have been developed at CEDRAT TECHNOLOGIES for several years and found several applications in space. Their well-known advantages (rapid response and precise positioning) have been used in valve designs to obtain either rapid or fine proportional valves. A first gas valve is using a small amplified piezo actuator and is further driven with a switched amplifier to

R. Le Letty; N. Lhermet; G. Patient; F. Claeyssen; M. Lang

2004-01-01

358

Control for steplessly variable transmission  

SciTech Connect

This patent describes a belt type steplessly variable transmission comprising belt-pulley means of variable speed ratio, fluid pressure operated actuator means for changing the speed ratio of the belt-pulley means, fluid control means for controlling a supply of fluid pressure to the actuator means to thereby determine the speed ratio of the belt-pulley means, the fluid control means including control valve means comprising a movable valve member having one end applied with a control signal pressure which changes in accordance with input speed of the belt-pulley means.

Koshio, T.

1987-06-09

359

Intermediate-term results after the aortic valve replacement using bileaflet mechanical prosthetic valve in children  

Microsoft Academic Search

Objective: Intermediate\\/long-term results after aortic valve replacement using bileaflet mechanical valve in children should be clarified as a standard of treatment of aortic valve disease in children. Methods: Forty-five patients aged under 15 years underwent 46 aortic valve replacements using bileaflet mechanical prosthetic valve. Patients' ages ranged from 1 to 15 years (9 years as a median value), and follow-up

Munetaka Masuda; Hideaki Kado; Yusuke Ando; Akira Shiose; Toshihide Nakano; Kouji Fukae; Yoshihisa Tanoue; Ryuji Tominaga

360

Intermediate-term results after the aortic valve replacement using bileaflet mechanical prosthetic valve in children  

Microsoft Academic Search

Objective: Intermediate\\/long-term results after aortic valve replacement using bileaflet mechanical valve in children should be clarified as a standard of treatment of aortic valve disease in children. Methods: Forty-five patients aged under 15 years underwent 46 aortic valve replacements using bileaflet mechanical prosthetic valve. Patients’ ages ranged from 1 to 15 years (9 years as a median value), and follow-up

Munetaka Masuda; Hideaki Kado; Yusuke Ando; Akira Shiose; Toshihide Nakano; Kouji Fukae; Yoshihisa Tanoue; Ryuji Tominaga

2008-01-01

361

Optimization for training neural nets  

Microsoft Academic Search

Various techniques of optimizing criterion functions to train neural-net classifiers are investigated. These techniques include three standard deterministic techniques (variable metric, conjugate gradient, and steepest descent), and a new stochastic technique. It is found that the stochastic technique is preferable on problems with large training sets and that the convergence rates of the variable metric and conjugate gradient techniques are

Etienne Barnard

1992-01-01

362

Inlet Flow Valve Engine Analyses  

NASA Technical Reports Server (NTRS)

Pratt&Whitney, under Task Order 13 of the NASA Large Engine Technology (LET) Contract, conducted a study to determine the operating characteristics, performance and weights of Inlet Flow Valve (IFV) propulsion concepts for a Mach 2.4 High Speed Civil Transport (HSCT).

Champagne, G. A.

2004-01-01

363

Pressure compensated flow control valve  

Microsoft Academic Search

The invention is an air flow control valve which is capable of maintaining a constant flow at the outlet despite changes in the inlet or outlet pressure. The device consists of a shell assembly with an inlet chamber and outlet chamber separated by a separation plate. The chambers are connected by an orifice. Also located within the inlet chamber is

Minteer; Daniel J

1999-01-01

364

Aortic valve surgery - minimally invasive  

MedlinePLUS

... and aortic valve are displayed on a computer in the operating room. This method is very precise. You may need ... the hospital. You will spend the first night in an intensive care unit (ICU). Nurses will monitor your condition at all times. Most ...

365

Microprocessor-Based Valved Controller  

NASA Technical Reports Server (NTRS)

New controller simpler, more precise, and lighter than predecessors. Mass-flow controller compensates for changing supply pressure and temperature such as occurs when gas-supply tank becomes depleted. By periodically updating calculation of mass-flow rate, controller determines correct new position for valve and keeps mass-flow rate nearly constant.

Norman, Arnold M., Jr.

1987-01-01

366

Hydraulic servo control spool valve  

DOEpatents

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

Miller, Donald M. (Sunnyside, WA)

1983-01-01

367

Rotary valve internal combustion engine  

Microsoft Academic Search

A rotary valve internal combustion engine is described which comprises: a cylinder block having a cylindrical recess therein, a cylindrical bore transverse to the cylindrical recess, an exhaust passageway leading from the cylindrical bore, and an intake passageway leading to the cylindrical bore. A cylindrical piston sealably reciprocable in the cylindrical recess wherein the space defined by the piston and

Coman

1987-01-01

368

Rotary valve internal combustion engine  

Microsoft Academic Search

A rotary valve internal combustion engine is described, comprising: an engine block; at least one cylinder in the engine block; at least one cylinder having a top end; cylinder head means located adjacent the top end of at least one cylinder, the cylinder head means having a cylindrically shaped cavity therein, the cylindrically shaped cavity being oriented in perpendicular relation

Bunk

1989-01-01

369

Clinical Use of a New Mitral Disc Valve  

PubMed Central

A disc valve of new design was used successfully for the replacement of the mitral valve in patients with rheumatic mitral valve disease. This valve would appear to have the following advantages over the mitral ball valve prosthesis: • Lower left atrial pressure after replacement. • Elimination of the hazard of left ventricular outflow tract obstruction with mitral valve replacement. • Decreased incidence of thromboembolization. • Abolition of possibility of ventricular septal irritation. Despite the better outlook for this valve compared with the ball valve for mitral valve substitution, the mitral valve should always be repaired whenever feasible. Repair is possible in the majority of patients. ImagesFigure 1. PMID:6039183

Kay, Jerome Harold; Tsuji, Harold K.; Redington, John V.; Kawashima, Yasunaru; Kagawa, Yuzuru; Yamada, Takashi; Caponegro, Peter; Mendez, Adolfo

1967-01-01

370

Manufacturable plastic microfluidic valves using thermal actuation.  

PubMed

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. PMID:19823723

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

2009-11-01

371

Mitral Valve Repair: The Chordae Tendineae  

PubMed Central

Repair of the mitral valve is the treatment of choice for mitral valve regurgitation when the anatomy is favorable. It is well known that mitral valve repair enjoys better clinical and functional results than any other type of valve substitute. This fact is beyond doubt regardless of the etiology of the valve lesion and is of particular importance in degenerative diseases. This review analyzes the most important advances in the knowledge of the anatomy, pathophysiology, and chordal function of the mitral valve as well as the different alternatives in the surgical repair and clinical results of the most prevalent diseases of the mitral valve. An attempt has been made to organize the acquired information available in a practical way. PMID:23304176

Mestres, Carlos-A.; Bernal, José M.

2012-01-01

372

Surgical reconstruction of the mitral valve  

PubMed Central

From Cutler's first attempt to treat the mitral valve by inserting a tenotomy knife through the left ventricle, to Carpentier's introduction of several repair techniques and a functional classification for assessing mitral valve lesions, the history of mitral valve treatment is exciting. Mitral diseases may be degenerative, ischaemic, infective or rheumatic, with or without superimposed impaired left ventricular function and calcification. Understanding the underlying pathological features is also important in determining whether mitral valve repair is feasible, how the valve should be repaired and the prospect for long?term durability of the repair. Recent advances in minimally invasive mitral valve surgery are promising but more effort is needed to ensure timely mitral valve repair. PMID:16339815

Tuladhar, S M; Punjabi, P P

2006-01-01

373

Transcatheter aortic valve replacement: postoperative CT findings of Sapien and CoreValve transcatheter heart valves.  

PubMed

Transcatheter aortic valve replacement represents one of the most exciting medical technical developments in recent years, offering a much-needed therapeutic alternative for patients with severe aortic valve stenosis who, due to comorbidities and advanced age, are considered to be inoperable or at high surgical risk. The efficacy of this procedure compared with standard surgical intervention has been properly validated in multicenter randomized controlled trials (PARTNER A and B trials), leading to widespread clinical implementation, with over 50,000 procedures currently being performed worldwide each year. Although much of the attention has rightly focused on the potential role of computed tomography (CT) in the preprocedural assessment of the aortic root and the establishment of imaging-guided valve-sizing algorithms, less is known regarding the postprocedural CT characteristics of transcatheter heart valves (THVs). However, given the increasing worldwide recognition and clinical implementation of these devices, they will no doubt be encountered with increasing frequency in patients referred for thoracic CT, either for postprocedural evaluation of the aortic root or for unrelated reasons. Familiarity with these devices and their CT characteristics will increase diagnostic confidence and the value of the radiology report. The authors describe the physical and imaging properties of the currently commercially available THVs, their normal postprocedural imaging appearances, and potential complications that can be detected at CT. In addition, they discuss the relative strengths and weaknesses of CT and echocardiography in this setting. PMID:25310415

Salgado, Rodrigo A; Budde, Ricardo P J; Leiner, Tim; Shivalkar, Bharati; Van Herck, Paul L; Op de Beeck, Bart J; Vrints, Christiaan; Buijsrogge, Marc P; Stella, Pieter R; Rodrigus, Inez; Bosmans, Johan; Parizel, Paul M

2014-10-01

374

Effects Ala54Thr polymorphism of FABP2 on obesity index and biochemical variable in response to a aerobic exercise training  

PubMed Central

The purpose of the current study was to investigate whether or not the FABP2 gene polymorphism modulated obesity indices, hemodynamic factor, blood lipid factor, and insulin resistance markers through 12-week aerobic exercise training in abdominal obesity group of Korean mid-life women. A total of 243 abdominally obese subjects of Korean mid-life women voluntarily participated in aerobic exercise training program for 12 weeks. Polymerase Chain Reaction with Restriction Fragment Length Polymorphism (PCR-RFLP) assay was used to assess the FABP2 genotype of the participants (117 of AA homozygotes, 100 of AT heterozygotes, 26 of TT homozygotes). Prior to the participation of the exercise training program, baseline obesity indices, hemodynamic factor, blood lipid factor, and insulin resistance markers were measured. All the measurements were replicated following the 12-week aerobic exercise training program, and then the following results were found. After 12-week aerobic exercise training program, wild type (Ala54Ala) and mutant type (Ala54Thr+Thr54Thr) significantly decreased weight (P > .001), BMI (P > .001), %bf (P > .001), waist circumference (P > .001), WHR (P > .001), muscle mass (wild type p < .022; mutant type P > .001), RHR (P > .001), viseceral adipose area (wild type p < .005; mutant type P > .001), subcutaneous area (P > .001), insulin (wild type p < .005; mutant type P > .001) and significantly increased VO2max (P > .001). And wild type significantly decresed NEFA (P > .05), glucose (P > .05), OGTT 120min glucose (P > .05) and significantly increased HDLC (p > .005). Mutant type significantly decreased SBP (P > .001), DBP (P > .01), TC (P > .01), LPL (P > .05), LDL (P > .001), HOMA index (P > .01). The result of the present study represents that regular aerobic exercise training may beneficially prevent obesity index, blood pressure, blood lipids and insulin resistance markers independent of FABP Ala54Thr wild type and mutant type.

Han, Tae Kyung

2013-01-01

375

Comparison of outcomes after aortic valve replacement with a mechanical valve or a bioprosthesis using microsimulation  

Microsoft Academic Search

BACKGROUND: Mechanical valves and bioprostheses are widely used for aortic\\u000a valve replacement. Though previous randomised studies indicate that there\\u000a is no important difference in outcome after implantation with either type\\u000a of valve, knowledge of outcomes after aortic valve replacement is\\u000a incomplete. OBJECTIVE: To predict age and sex specific outcomes of\\u000a patients after aortic valve replacement with bileaflet mechanical valves\\u000a and

J. P. A. Puvimanasinghe; M. B. Edwards; M. J. C. Eijkemans; E. W. Steyerberg; Herwerden van L. A; K. M. Taylor; G. L. Grunkemeier; J. D. F. Habbema; A. J. J. C. Bogers; J. J. M. Takkenberg

2004-01-01

376

Bayesian sensitivity analysis of a model of the aortic valve.  

PubMed

Understanding the mechanics of the aortic valve has been a focus of attention for many years in the biomechanics literature, with the aim of improving the longevity of prosthetic replacements. Finite element models have been extensively used to investigate stresses and deformations in the valve in considerable detail. However, the effect of uncertainties in loading, material properties and model dimensions has remained uninvestigated. This paper presents a formal statistical consideration of a selected set of uncertainties on a fluid-driven finite element model of the aortic valve and examines the magnitudes of the resulting output uncertainties. Furthermore, the importance of each parameter is investigated by means of a global sensitivity analysis. To reduce computational cost, a Bayesian emulator-based approach is adopted whereby a Gaussian process is fitted to a small set of training data and then used to infer detailed sensitivity analysis information. From the set of uncertain parameters considered, it was found that output standard deviations were as high as 44% of the mean. It was also found that the material properties of the sinus and aorta were considerably more important in determining leaflet stress than the material properties of the leaflets themselves. PMID:21481873

Becker, W; Rowson, J; Oakley, J E; Yoxall, A; Manson, G; Worden, K

2011-05-17

377

Thermostatic Valves Containing Silicone-Oil Actuators  

NASA Technical Reports Server (NTRS)

Flow-splitting and flow-mixing thermally actuated spool valves have been developed for controlling flows of a heat-transfer fluid in a temperature-regulation system aboard the Mars Science Laboratory (MSL) rover. Valves like these could also be useful in terrestrial temperature-regulation systems, including automobile air-conditioning systems and general refrigeration systems. These valves are required to provide smoother actuation over a wider temperature range than the flow-splitting, thermally actuated spool valves used in the Mars Explorer Rover (MER). Also, whereas the MER valves are unstable (tending to oscillate) in certain transition temperature ranges, these valves are required not to oscillate. The MER valves are actuated by thermal expansion of a wax against spring-loaded piston rods (as in common automotive thermostats). The MSL valves contain similar actuators that utilize thermal expansion of a silicone oil, because silicone-oil actuators were found to afford greater and more nearly linear displacements, needed for smoother actuation, over the required wider temperature range. The MSL valves also feature improved spool designs that reflect greater understanding of fluid dynamics, consideration of pressure drops in valves, and a requirement for balancing of pressures in different flow branches.

Bhandari, Pradeep; Birur, Gajanana C.; Bame, David P.; Karlmann, Paul B.; Prina, Mauro; Young, William; Fisher, Richard

2009-01-01

378

Control system for a continuously variable transmission  

SciTech Connect

This patent describes a control system for a continuously variable belt-drive transmission having a selector device including a drive range position, a drive pulley having a hydraulically shiftable disc and a servo chamber for shifting the disc, a driven pulley having a hydraulically shiftable disc and a servo chamber for shifting the disc, and a belt engaged with both the pulleys, an hydraulic control circuit for supplying oil to the servo chambers and for draining the servo chambers, the hydraulic control circuit being provided with a pressure regulator valve for providing a line pressure and a transmission ratio control valve for applying the line pressure to the servo chamber of the drive pulley. The improvement comprises: a first drain passage from the pressure regulator valve; a second drain passage from the transmission ratio control valve; a first check valve provided in the first drain passage and a second check valve provided in the second drain passage for building up supplementary low pressure in both drain passages at upstream of both the check valves; a supplementary oil passage communicating both the first and second drain passages at upstream of the check valves for supplying a part of drain oil to the servo chamber of the drive pulley.

Sakai, Y.

1987-11-03

379

Liquid crystal light valve structures  

NASA Technical Reports Server (NTRS)

An improved photosensor film and liquid crystal light valves embodying said film is provided. The photosensor film and liquid crystal light valve is characterized by a significant lower image retention time while maintaining acceptable photosensitivity. The photosensor film is produced by sputter depositing CdS onto an ITO substrate in an atmosphere of argon/H2S gas while maintaining the substrate at a temperature in the range of about 130 C to about 200 C and while introducing nitrogen gas into the system to the extent of not more than about 1% of plasma mixture. Following sputter deposition of the CdS, the film is annealed in an inert gas at temperatures ranging from about 300 C to about 425 C.

Koda, N. J. (inventor)

1985-01-01

380

Mechanical Prosthetic Valves and Pregnancy  

PubMed Central

Choosing the best anticoagulant therapy for a pregnant patient with a mechanical prosthetic valve is controversial and the published international guidelines contain no clear-cut consensus on the best approach. This is due to the fact that there is presently no anticoagulant which can reliably decrease thromboembolic events while avoiding damage to the fetus. Current treatments include either continuing oral warfarin or substituting warfarin for subcutaneous unfractionated heparin or low-molecular-weight heparin (LMWH) in the first trimester (6–12 weeks) or at any point throughout the pregnancy. However, LMWH, while widely-prescribed, requires close monitoring of the blood anti-factor Xa levels. Unfortunately, facilities for such monitoring are not universally available, such as within hospitals in developing countries. This review evaluates the leading international guidelines concerning anticoagulant therapy in pregnant patients with mechanical prosthetic valves as well as proposing a simplified guideline which may be more relevant to hospitals in this region. PMID:25364545

Panduranga, Prashanth; El-Deeb, Mohammed; Jha, Chitra

2014-01-01

381

Outdoor Training.  

ERIC Educational Resources Information Center

Includes "Outdoor Training: Revolution or Fad?" (Wagner, Baldwin, Roland); "Getting the Most out of Outdoor Training" (Buller, Cragun, McEvoy); and "Outdoor Training Companies" (a directory of more than 100 firms). (JOW)

Wagner, Richard J.; And Others

1991-01-01

382

Management of multiple valve disease.  

PubMed

Multivalvular heart disease is not an uncommon situation, but the paucity of data for each specific situation does not allow the proposal of a standardised, evidence-based management strategy. This paper aims at reviewing the available evidence on the management of multivalvular disease, taking into account the interactions between different valve lesions, the diagnostic pitfalls and the strategies that should be considered in the presence of multiple valvular disease. PMID:21156677

Unger, Philippe; Rosenhek, Raphael; Dedobbeleer, Chantal; Berrebi, Alain; Lancellotti, Patrizio

2011-02-01

383

Miniaturized double latching solenoid valve  

NASA Technical Reports Server (NTRS)

A valve includes a generally elongate pintle; a spacer having a rounded surface that bears against the pintle; a bulbous tip fixed to the spacer; and a hollow, generally cylindrical collar fixed to the pintle, the collar enclosing the spacer and the tip and including an opening through which a portion of the tip extends, the opening in the collar and interior of the collar being of a size such that the tip floats therein.

Smith, James T. (Inventor)

2010-01-01

384

Transcatheter valve repair\\/implantation  

Microsoft Academic Search

Real time 3-dimensional transesophageal echo is a relatively new technology that enables online imaging that is highly accurate\\u000a and precise for evaluating cardiac structures. Moreover, this methodology allows for accurate online guidance of interventional\\u000a cardiac procedures for structural heart disease. In this report, we describe the use of real time, 3D transesophageal (TEE)\\u000a for aortic valve replacement with percutaneous, bioprosthetic

Robert J. Siegel; Huai Luo; Simon Biner

385

Echocardiography of the mitral valve.  

PubMed

Echocardiography is the primary imaging modality for assessment of the mitral valve (MV). It provides an accurate and non-invasive tool to assess the morphology, geometry and function of the MV apparatus, which form the basis of the mechanisms and classification of MV disease. This review highlights the mechanistic insights into MV dysfunction by echocardiography and the critical role of echocardiography in the quantitative assessment of the severity of mitral regurgitation and mitral stenosis. PMID:25081402

Zeng, Xin; Tan, Timothy C; Dudzinski, David M; Hung, Judy

2014-01-01

386

Long-Term Results of Mechanical Valve Replacement: Isolated Mitral Valve Replacement and Mitral-Aortic Valve Replacement  

Microsoft Academic Search

The long-term results of mechanical valve replace- ment are satisfactory in terms of both survival and quality of life. In a series of 440 isolated mitral valve replacements (MVR) with a St. Jude Medical prosthesis (1), the overall actuarial survival rate was 63 ± 3.3% at 19 years, while the valve-related actuarial survival was 83 ± 2.7%. The operative mortality

J.-P. Remadi; D. Duveau

387

Vascularization of bioprosthetic valve material  

NASA Astrophysics Data System (ADS)

Cell membrane remnants represent a probable nucleation site for calcium deposition in bioprosthetic heart valves. Calcification is a primary failure mode of both bovine pericardial and porcine aortic heterograft bioprosthesis but the nonuniform pattern of calcium distribution within the tissue remains unexplained. Searching for a likely cellular source, we considered the possibility of a previously overlooked small blood vessel network. Using a videomicroscopy technique, we examined 5 matched pairs of porcine aortic and pulmonary valves and 14 samples from 6 bovine pericardia. Tissue was placed on a Leitz Metallux microscope and transilluminated with a 75 watt mercury lamp. Video images were obtained using a silicon intensified target camera equipped with a 431 nm interference filter to maximize contrast of red cells trapped in a capillary microvasculature. Video images were recorded for analysis on a Silicon Graphics Image Analysis work station equipped with a video frame grabber. For porcine valves, the technique demonstrated a vascular bed in the central spongiosa at cusp bases with vessel sizes from 6-80 micrometers . Bovine pericardium differed with a more uniform distribution of 7-100 micrometers vessels residing centrally. Thus, small blood vessel endothelial cells provide a potential explanation patterns of bioprosthetic calcification.

Boughner, Derek R.; Dunmore-Buyze, Joy; Heenatigala, Dino; Lohmann, Tara; Ellis, Chris G.

1999-04-01

388

Segmented ball valve is easy to open and close  

NASA Technical Reports Server (NTRS)

Segmented ball valve and flowmeter in the same spherical housing provide a valve that will handle large fluid volume without bulkiness and weight of blade valves or conventional ball valves. The valve is easily opened or closed and the flowmeter remains stationary, so errors are eliminated.

Prono, E.; Shinault, L. H.; Speisman, C.

1966-01-01

389

Flow Characteristics of Butterfly Valve by PIV and CFD  

NASA Astrophysics Data System (ADS)

Butterfly valves are widely used as on-off and control valves for industrial process. The importance of butterfly valves as control valves has been increasing because the pressure loss is smaller than other types of valves and compactness is very desirable for installation. These features are desirable for saving energy and high efficiency of instruments.

Kim, S. W.; Kim, J. H.; Choi, Y. D.; Lee, Y. H.

390

Smoothelin-positive cells in human and porcine semilunar valves  

Microsoft Academic Search

Our aim was to further characterize the interstitial cell phenotypes of normal porcine and human semilunar valves, information necessary for the design of bioengineered valves and for the understanding of valve disease processes such as aortic valve sclerosis. Existence of fibroblasts, myofibroblasts, and smooth muscle-like cells within semilunar heart valves has been established. However, the nature of the smooth muscle

Massimo Cimini; Kem A. Rogers; Derek R. Boughner

2003-01-01

391

Study on Inflow-Drive Valves for Pulse Detonation Engines  

Microsoft Academic Search

In the present study, a dynamics model of an inflow-drive valve for pulse detonation engines (PDEs) is proposed, in which system the inflow of the valve periodically drives the valve piston. Since the inflow-drive valve needs no energy source to drive the piston, the mass flow rate divided by the valve mass is relatively large, and the response time for

Hiroyuki Yamaguchi; Ken Matsuoka; Jun Yageta; Jiro Kasahara

2009-01-01

392

Influence of body size and gender on valve movement responses of a freshwater bivalve to uranium.  

PubMed

Body size, age, and gender (male or female) are important variables influencing many aspects of the ecology, physiology, and survival of animals. However, no data are available on the influence of these variables on bivalves exposed to sublethal metal concentrations. This study tested whether the valve movement responses (measured in terms of the duration or frequency of valve opening) of the Australian tropical freshwater unionoid bivalve, Velesunio angasi, exposed to sublethal uranium (U) concentrations in a standard synthetic water (pH, 6.0; hardness and alkalinity, 4 mg/L as CaCO(3)) were influenced by body size (shell length, shell breadth, or dry tissue weight), age, and/or gender. The valve movement responses of V. angasi to U were independent of gender; the sensitivity of males to U was not significantly (p > 0.05) different from that of females. In contrast, the valve movement responses of V. angasi to U were size- and age-dependent; smaller and younger individuals (median shell length = 36.8 mm; median age = 0.7 years) were 22% more sensitive (p variability in valve movement responses was reduced by 81%. Consequently, errors (95% confidence limits) associated with valve movement response (EC(50)) values were substantially reduced (75%). Hence, the ability to demonstrate statistically significant (p valve movement responses between U exposure concentrations was enhanced. This, in turn, may permit better estimates of the risk of the effects of U exposures to bivalve populations. PMID:12635101

Markich, Scott J

2003-04-01

393

Hydraulic orifice formula for echographic measurement of the mitral valve area in stenosis. Application to M-mode echocardiography and correlation with cardiac catheterisation.  

PubMed Central

A mitral valve orifice equation has been formulated which allows the computation of mitral valve area (A) from the echographically measurable variables of stroke volume (SV) and diastolic filling period (DFP) in seconds per minute by the formula, A=21 (SV)/(DFP)2. Mitral valve areas computed from M-mode echographic measurements are shown to correlate with areas computed by the Gorlin formula (r-0.90) for resting state conditions of predominant mitral stenosis of clinical grades 2 to 4. The results suggest that, in the absence of wall motion irregularities, M-mode echocardiography can quantitatively assess the mitral valve area in stenosis. PMID:7272110

Seitz, W S; Furukawa, K

1981-01-01

394

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

Code of Federal Regulations, 2010 CFR

...SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.137 Inhalation and exhalation valves; check valves;...

2010-10-01

395

40 CFR 60.483-1 - Alternative standards for valves-allowable percentage of valves leaking.  

Code of Federal Regulations, 2010 CFR

...Industry for which Construction, Reconstruction, or Modification Commenced After January 5, 1981, and on or Before November 7, 2006 § 60.483-1 Alternative standards for valves—allowable percentage of valves leaking. (a) An owner or...

2010-07-01

396

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

DOEpatents

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

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

2012-04-17

397

Imaging of Cardiac Valves by Computed Tomography  

PubMed Central

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 CT for planning of transcatheter aortic valve implantation (TAVI), an emerging effective treatment option for patients with severe aortic stenosis. A special focus is placed on clinical applications of cardiac CT in the context of valvular disease. PMID:24490107

Feuchtner, Gudrun

2013-01-01

398

In vitro evaluation of right ventricular outflow tract reconstruction with bicuspid valved polytetrafluoroethylene conduit.  

PubMed

Conduits available for right ventricular outflow tract (RVOT) reconstruction eventually become stenotic and/or insufficient due to calcification. In order to reduce the incidence of reoperations we have developed and used a bicuspid valved polytetrafluoroethylene (PTFE) conduit for the RVOT reconstruction. The purpose of this study is to investigate the hemodynamic performance of the new design using a pediatric in vitro right heart mock loop. PTFE conduit has been used for the complete biventricular repair of 20 patients (age 1.7±6 years) with cyanotic congenital defects. To account for the large variability of conduit sizes, 14, 16, 22, and 24-mm conduit sizes were evaluated using an in vitro flow loop comprised of a pulsatile pump with cardiac output (CO) of 1.2-3.2L/min, bicuspid valved RVOT conduit, pulmonary artery, venous compartments, and the flow visualization setup. We recorded the diastolic valve leakage and pre- and post-conduit pressures in static and pulsatile settings. In vitro valve function and overall hemodynamic performance was evaluated using high-speed cameras and ultrasonic flow probes. Three-dimensional flow fields for different in vivo conduit curvatures and inflow regimes were calculated by computational fluid dynamics (CFD) analysis to further aid the conduit design process. The average pressure drop over the valved conduits was 0.8±1.7mm Hg for the CO range tested. Typical values for regurgitant fraction, peak-to-peak pressure gradient, and effective office area were 23±2.1%, 13±2.4mm Hg, and 1.56±0.2 cm(2) , respectively. High-speed videos captured the intact valve motion with asymmetrical valve opening during the systole. CFD simulations demonstrated the flow skewness toward the major curvature of the conduit based on the pulmonic curvature. In vitro evaluation of the bicuspid valved PTFE conduit coincides well with acceptable early clinical performance (mild insufficiency), with relatively low pressure drop, and intact valve motion independent from the conduit curvature, orientation or valve location, but at the expense of increased diastolic flow regurgitation. These findings benchmark the baseline performance of the bicuspid valved conduit and will be used for future designs to improve valve competency. PMID:21092044

Dur, Onur; Yoshida, Masahiro; Manor, Philip; Mayfield, Alice; Wearden, Peter D; Morell, Victor O; Pekkan, Kerem

2010-11-01

399

Valve and dash-pot assembly  

DOEpatents

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

Chang, Shih-Chih (Richland, WA)

1986-01-01

400

Propellant actuated nuclear reactor steam depressurization valve  

DOEpatents

A nuclear fission reactor combined with a propellant actuated depressurization and/or water injection valve is disclosed. The depressurization valve releases pressure from a water cooled, steam producing nuclear reactor when required to insure the safety of the reactor. Depressurization of the reactor pressure vessel enables gravity feeding of supplementary coolant water through the water injection valve to the reactor pressure vessel to prevent damage to the fuel core.

Ehrke, Alan C. (San Jose, CA); Knepp, John B. (San Jose, CA); Skoda, George I. (Santa Clara, CA)

1992-01-01

401

Transcriptional Regulation of Heart Valve Progenitor Cells  

Microsoft Academic Search

The development and normal function of the heart valves requires complex interactions among signaling molecules, transcription\\u000a factors and structural proteins that are tightly regulated in time and space. Here we review the roles of critical transcription\\u000a factors that are required for specific aspects of normal valve development. The early progenitors of the heart valves are\\u000a localized in endocardial cushions that

Santanu Chakraborty; Michelle D. Combs; Katherine E. Yutzey

2010-01-01

402

Improved valve and dash-pot assembly  

DOEpatents

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

Chang, S.C.

1985-04-23

403

Aortic homografts versus mechanical valves in aortic valve replacement in young patients: a retrospective study  

Microsoft Academic Search

Background. Whether aortic homografts (AH) or mechanical devices (MD) are the valves of choice for aortic valve replacement in young patients (age 20 to 50 years) is unclear. Hence, we examined all aortic valve replacements performed with AH and MD in a retrospective study.Methods. Between 1988 and 1995, 45 patients (mean age, 38.6 ± 8.5 years) underwent aortic valve replacement

Christoph Gross; Uwe Klima; Rudolf Mair; Peter Brücke

1998-01-01

404

Early pericardial valve deterioration as a result of adhesions with native mitral valve.  

PubMed

We report an unusual case of early pericardial tissue valve prosthesis deterioration that required replacement. Four years after mitral valve replacement, 1 of the 3 leaflets of the valve was thickened and retracted in a fixed open position, which resulted in severe mitral insufficiency. The cause of this was adhesion of the leaflet and the patient's own retained posterior mitral valve leaflet. The finding was confirmed at operation and by histologic examination. PMID:24996713

Rohn, Vilem; Spacek, Miroslav; Sachl, Robert; Vitkova, Ivana

2014-07-01

405

Current Status of Prosthetic Cardiac Valves  

PubMed Central

The majority of patients with acquired valvular heart disease have severe damage to valves which is not amenable to repair but can now be treated by valve replacement with an acceptable mortality and morbidity. The caged ball or disc valve is widely used and is proving clinically satisfactory for cardiac valve replacement. Thromboembolism is the significant complication. With improvement in technique the incidence of infection, detachment and other complications has been reduced. ImagesFigure 1.Figure 2.Figure 4.Figure 5.Figure 6.Figure 7.Figure 8.Figure 9.Figure 10. PMID:6039188

Huse, Wilfred M.; Wareham, Ellsworth E.

1967-01-01

406

Solve valve noise and cavitation problems  

SciTech Connect

A clear understanding of aerodynamic noise theory and cavitation will avoid most major valve problems in process plants and allow the valve engineer to design out potential problems. On the other hand, the plant owner has to recognize that such valves may require a cost premium. However, such a premium will be recovered in a small amount of time because of the savings from reduced downtime and lower maintenance costs. Pressure reducing valves used on gases or high pressure steam valves, such as turbine bypass valves, convert substantial energy into heat and a lower pressure level. Unfortunately, this can only be done by accelerating the gas in one or more orifices and then decelerating it rapidly again through a turbulence mechanism or super-sonic shock cells. This causes a lot of noise and vibration. Valve engineering science has made substantial strides in the past few years, and one is now able to predict cavitation and aerodynamic sound levels before a valve is purchased. Similarly, newer valve sizes incorporate features that reduce noise and cavitation effects. Some other minor problems are resonant plug vibration and flashing. The paper discusses how to predict aerodynamic sound, how close can one estimate the sound level, cavitation, and incorrect installation.

Baumann, H.D. [Fisher Controls International, Inc., St. Louis, MO (United States)

1997-03-01

407

Reliability Enhancement of HVDC Transmission by Standardization of Thyristor Valves and Valve Testing  

Microsoft Academic Search

After more than thirty years development bulk power transmission by means of HVDC thyristor valves has become an industry standard. Concept of standard thyristor valve design has been adopted in many HVDC projects for reliability enhancement in recent years. Choosing of standard components, using well-proven design structure and rigours valve design verification program and test circuit are the three most

Baoliang Sheng; Hans-Ola Bjarme; Hans Johansson

408

REGRESSION OF LEFT VENTRICULAR HYPERTROPHY AFTER AORTIC VALVE REPLACEMENT FOR AORTIC STENOSIS WITH DIFFERENT VALVE SUBSTITUTES  

Microsoft Academic Search

Objective: Stentless biologic aortic valves are less obstructive than stented biologic or mechanical valves. Their superior hemodynamic perfor- mances are expected to reflect in better regression of left ventricular hypertrophy. We compared the regression of left ventricular hypertro- phy in 3 groups of patients undergoing aortic valve replacement for severe aortic stenosis. Group I (10 patients) received stentless biologic aortic

Ruggero De Paulis; Luigi Sommariva; Luisa Colagrande; Giovanni Maria De Matteis; Simona Fratini; Fabrizio Tomai; Carlo Bassano; Alfonso Penta de Peppo; Luigi Chiariello

2010-01-01

409

A worn Björk–Shiley prosthetic valve without valve dysfunction observed during ascending aortic replacement  

PubMed Central

Key Clinical Message The implanted first-generation Björk–Shiley valve in our patient was functioning well before aortic surgery, but we replaced the valve because we confirmed disc erosion 39 years after implantation during the surgery. We judged that the implanted valve was no longer capable of maintaining the patient's life.

Komi, Misao; Sugaya, Akira; Akutsu, Hirohiko; Sato, Hirotaka; Kaminishi, Yuichiro; Misawa, Yoshio

2014-01-01

410

Project W-314 241-AN-A valve pit upgrade acceptance for beneficial use  

SciTech Connect

This report identifies the responsibilities and requirements, applicable to the 241-AN-A Valve Pit Upgrades portion of Project W-314, for Acceptance for Beneficial Use in accordance with HNF-IP-0842, Vol IV, Sec 3.12. At project turnover, the end user accepts the affected Structures, Systems, and Components (SSCs) for beneficial use. This checklist is used to help the end user ensure that all documentation, training, and testing requirements are met prior to turnover. This checklist specifically identifies those items related to the upgrading of the 241-AN-A valve pit. The upgrades include: the installation of jumper/valve manifolds with position sensors, replacement pit leak detection systems, construction of replacement cover blocks, and electrical upgrades to support the instrumentation upgrades.

HAMMERS, J.S.

1999-07-21

411

Project W-314 241-AN-B valve pit upgrade acceptance for beneficial use  

SciTech Connect

This report identifies the responsibilities and requirements, applicable to the 241-AN-B Valve Pit Upgrades portion of Project W-314, for Acceptance for Beneficial Use in accordance with HNF-IP-0842, Vol IV, Sec 3.12. At project turnover, the end user accepts the affected Structures, Systems, and Components (SSCs) for beneficial use. This checklist is used to help the end user ensure that all documentation, training, and testing requirements are met prior to turnover. This checklist specifically identifies those items related to the upgrading of the 241-AN-B valve pit. The upgrades include: the installation of jumper/valve manifolds with position sensors, replacement pit leak detection systems, construction of replacement cover blocks, and electrical upgrades to support the instrumentation upgrades.

HAMMERS, J.S.

1999-07-21

412

Right Ventricular Outflow Tract Reconstruction with Bicuspid Valved Polytetrafluoroethylene Conduit  

E-print Network

Right Ventricular Outflow Tract Reconstruction with Bicuspid Valved Polytetrafluoroethylene Conduit we have developed and utilized a bicuspid valved polytetrafluoroethylene conduit (PTFE we have developed and utilized a bicuspid valved polytetrafluoroethylene (PTFE) conduit using

Pekkan, Kerem

413

49 CFR 192.365 - Service lines: Location of valves.  

Code of Federal Regulations, 2012 CFR

...MINIMUM FEDERAL SAFETY STANDARDS Customer Meters, Service Regulators, and Service Lines...valves. (a) Relation to regulator or meter. Each service-line valve must be...there is no regulator, upstream of the meter. (b) Outside valves. Each...

2012-10-01

414

49 CFR 192.365 - Service lines: Location of valves.  

Code of Federal Regulations, 2013 CFR

...MINIMUM FEDERAL SAFETY STANDARDS Customer Meters, Service Regulators, and Service Lines...valves. (a) Relation to regulator or meter. Each service-line valve must be...there is no regulator, upstream of the meter. (b) Outside valves. Each...

2013-10-01

415

49 CFR 192.365 - Service lines: Location of valves.  

Code of Federal Regulations, 2010 CFR

...MINIMUM FEDERAL SAFETY STANDARDS Customer Meters, Service Regulators, and Service Lines...valves. (a) Relation to regulator or meter. Each service-line valve must be...there is no regulator, upstream of the meter. (b) Outside valves. Each...

2010-10-01

416

49 CFR 192.365 - Service lines: Location of valves.  

Code of Federal Regulations, 2011 CFR

...MINIMUM FEDERAL SAFETY STANDARDS Customer Meters, Service Regulators, and Service Lines...valves. (a) Relation to regulator or meter. Each service-line valve must be...there is no regulator, upstream of the meter. (b) Outside valves. Each...

2011-10-01

417

42 CFR 84.123 - Exhalation valve leakage test.  

Code of Federal Regulations, 2011 CFR

...SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.123 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be subjected to a...

2011-10-01

418

42 CFR 84.123 - Exhalation valve leakage test.  

Code of Federal Regulations, 2010 CFR

...SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Gas Masks § 84.123 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be subjected to a...

2010-10-01

419

TCR and TSC thyristor valves for Rowville SVC replacement project  

Microsoft Academic Search

This paper presents the design of the thyristor valves for the Rowville SVC replacement project. The thyristor valves are based on AREVA's latest developed S500 series valve design and make use of 8.5kV 5\\

J. Z. Cao; M. Donoghue; C. Horwill; A. Singh

2010-01-01

420

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

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

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

421

21 CFR 870.3945 - Prosthetic heart valve sizer.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...Prosthetic Devices § 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to...

2012-04-01

422

21 CFR 870.3925 - Replacement heart valve.  

...2014-04-01 2014-04-01 false Replacement heart valve. 870.3925 Section 870.3925...Prosthetic Devices § 870.3925 Replacement heart valve. (a) Identification. A replacement heart valve is a device intended to perform...

2014-04-01

423

21 CFR 870.3935 - Prosthetic heart valve holder.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Prosthetic heart valve holder. 870.3935 Section 870...Prosthetic Devices § 870.3935 Prosthetic heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold...

2013-04-01

424

21 CFR 870.3935 - Prosthetic heart valve holder.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Prosthetic heart valve holder. 870.3935 Section 870...Prosthetic Devices § 870.3935 Prosthetic heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold...

2011-04-01

425

21 CFR 870.3925 - Replacement heart valve.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Replacement heart valve. 870.3925 Section 870.3925...Prosthetic Devices § 870.3925 Replacement heart valve. (a) Identification. A replacement heart valve is a device intended to perform...

2013-04-01

426

21 CFR 870.3945 - Prosthetic heart valve sizer.  

...2014-04-01 2014-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...Prosthetic Devices § 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to...

2014-04-01

427

21 CFR 870.3935 - Prosthetic heart valve holder.  

...2014-04-01 2014-04-01 false Prosthetic heart valve holder. 870.3935 Section 870...Prosthetic Devices § 870.3935 Prosthetic heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold...

2014-04-01

428

21 CFR 870.3935 - Prosthetic heart valve holder.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Prosthetic heart valve holder. 870.3935 Section 870...Prosthetic Devices § 870.3935 Prosthetic heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold...

2012-04-01

429

21 CFR 870.3945 - Prosthetic heart valve sizer.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...Prosthetic Devices § 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to...

2011-04-01

430

21 CFR 870.3925 - Replacement heart valve.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Replacement heart valve. 870.3925 Section 870.3925...Prosthetic Devices § 870.3925 Replacement heart valve. (a) Identification. A replacement heart valve is a device intended to perform...

2011-04-01

431

21 CFR 870.3925 - Replacement heart valve.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Replacement heart valve. 870.3925 Section 870.3925...Prosthetic Devices § 870.3925 Replacement heart valve. (a) Identification. A replacement heart valve is a device intended to perform...

2012-04-01

432

21 CFR 870.3945 - Prosthetic heart valve sizer.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...Prosthetic Devices § 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to...

2013-04-01

433

All-metal valve structure for gas systems  

DOEpatents

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

Baker, R.W.; Pawlak, D.A.; Ramey, A.J.

1982-06-10

434

Total reconstruction of the mitral valve with autopericardium: anatomical study.  

PubMed

Mitral valve repair has several advantages over prosthetic valve replacement. A new technique of total reconstruction of the mitral valve with autologous pericardium is described. The native mitral valve leaflets and chordae were excised from 10 human cadaver hearts, in the same way as for prosthetic valve replacement. The dimensions of the physiologically normal mitral valve were used to calculate the parameters for tailoring a corresponding new valve. Autologous pericardium was fixed in 0.625% glutaraldehyde solution for 10 minutes. The calculated parameters of the mitral valve were marked on the pericardium. The new valve was fashioned and inserted in the native valve position. Hydraulic probes showed good competence in all 10 reconstructed mitral valves. This method might be a good alternative to prosthetic valve replacement. PMID:12079937

Gasparyan, Vahe C; Galstyan, Van S

2002-06-01

435

Hydraulic engine valve actuation system including independent feedback control  

DOEpatents

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

Marriott, Craig D

2013-06-04

436

46 CFR 154.1846 - Relief valves: Changing set pressure.  

...false Relief valves: Changing set pressure. 154.1846 Section 154.1846...1846 Relief valves: Changing set pressure. The master shall: (a) Supervise the changing of the set pressure of relief valves under §...

2014-10-01

437

Variable Speed Pumping for Level Control  

E-print Network

The purpose of this paper is to describe an application of variable speed pumping to level control of an industrial process. Topics include a comparison of the process using control valves with a variable speed system, an energy savings and cost...

Vasel, M.

1982-01-01

438

New developments in catheter interventional treatment of heart valve disease: percutaneous valve replacement and percutaneous valve repair  

Microsoft Academic Search

Summary  BACKGROUND: Until recently, percutaneous intervention in valvular heart disease was restricted to balloon valvotomy for stenotic lesions. Although this technique has proven to be effective in mitral stenosis, pulmonic and tricuspid stenosis, balloon valvotomy of the aortic valve has been abandoned in calcific aortic stenosis, the most common valve disease in adults, and is successfully performed only in children and

H. Baumgartner

2006-01-01

439

Isolation of murine valve endothelial cells.  

PubMed

Normal valve structures consist of stratified layers of specialized extracellular matrix (ECM) interspersed with valve interstitial cells (VICs) and surrounded by a monolayer of valve endothelial cells (VECs). VECs play essential roles in establishing the valve structures during embryonic development, and are important for maintaining life-long valve integrity and function. In contrast to a continuous endothelium over the surface of healthy valve leaflets, VEC disruption is commonly observed in malfunctioning valves and is associated with pathological processes that promote valve disease and dysfunction. Despite the clinical relevance, focused studies determining the contribution of VECs to development and disease processes are limited. The isolation of VECs from animal models would allow for cell-specific experimentation. VECs have been isolated from large animal adult models but due to their small population size, fragileness, and lack of specific markers, no reports of VEC isolations in embryos or adult small animal models have been reported. Here we describe a novel method that allows for the direct isolation of VECs from mice at embryonic and adult stages. Utilizing the Tie2-GFP reporter model that labels all endothelial cells with Green Fluorescent Protein (GFP), we have been successful in isolating GFP-positive (and negative) cells from the semilunar and atrioventricular valve regions using fluorescence activated cell sorting (FACS). Isolated GFP-positive VECs are enriched for endothelial markers, including CD31 and von Willebrand Factor (vWF), and retain endothelial cell expression when cultured; while, GFP-negative cells exhibit molecular profiles and cell shapes consistent with VIC phenotypes. The ability to isolate embryonic and adult murine VECs allows for previously unattainable molecular and functional studies to be carried out on a specific valve cell population, which will greatly improve our understanding of valve development and disease mechanisms. PMID:25177896

Miller, Lindsey J; Lincoln, Joy

2014-01-01

440

Classification of heart valve sounds from experiments in an anechoic water tank  

SciTech Connect

In vivo studies in both sheep and humans were plagued by a number of problems including movement artifacts, biological noise, low signal-to-noise ratio (SNR), chest-wall reverberation, and limited bandwidth recordings as discussed by [1]. To overcome these problems it was decided to record heart valve sounds under controlled conditions deep in an anechoic water tank, free from reverberation noise. The main goal of this experiment was to obtain measurements of ''pure'' heart valve sounds free of the scattering effects of the body. Experiments were conducted at the Transdec facility in San Diego [2]. We used a high quality hydrophone together with a wide-band data acquisition system [2]. We recorded sounds from 100 repetitions of the opening-closing cycles on each of 50 different heart valves, including 21 SLS valves and 29 intact valves. The power spectrum of the opening and closing phases of each cycle were calculated and outlier spectra removed as described by Candy [2]. In this report, we discuss the results of our classification of the heart valve sound measurements. The goal of this classification task was to apply the fundamental classification algorithms developed for the clinical data in 1994 and 1996 to the measurements from the anechoic water tank. From the beginning of this project, LLNL's responsibility has been to process and classify the heart valve sounds. For this experiment, however, we processed both the opening sounds and closing sounds for comparison purposes. The results of this experiment show that the classifier did not perform well because of low signal-to-noise ratio and excessive variability in signal power from beat-to-beat for a given valve.

Axelrod, M C; Clark, G A; Scott, D

1999-06-01

441

Control Valve Trajectories for SOFC Hybrid System Startup  

SciTech Connect

Control and management of cathode airflow in a solid oxide fuel cell gas turbine hybrid power system was analyzed using the Hybrid Performance (HyPer) hardware simulation at the National Energy Technology (NETL), U.S. Department of Energy. This work delves into previously unexplored operating practices for HyPer, via simultaneous manipulation of bypass valves and the electric load on the generator. The work is preparatory to the development of a Multi-Input, Multi-Output (MIMO) controller for HyPer. A factorial design of experiments was conducted to acquire data for 81 different combinations of the manipulated variables, which consisted of three air flow control valves and the electric load on the turbine generator. From this data the response surface for the cathode airflow with respect to bypass valve positions was analyzed. Of particular interest is the control of airflow through the cathode during system startup and during large load swings. This paper presents an algorithm for controlling air mass flow through the cathode based on a modification of the steepest ascent method.

Gorrell, Megan; Banta, Larry; Rosen, William; Restrepo, Bernardo; Tucker, David

2012-07-01

442

Preventing cavitation in butterfly valves  

SciTech Connect

Some of the mechanical problems that plagued butterfly valves in the past are discussed. The authors suggest integrated packages to alleviate these problems. These packages include such innovations as backlash-free stem connections, allenclosed actuator packages, and torque-compensated vanes. Some disadvantages to these packages are outlined and examined, including: high noise levels with compressible fluids, and an increased tendency to cavitate with liquids. A discussion follows on cavitation--how it is caused, just how much of it can be tolerated, and how it can be avoided or reduced.

Baumann, H.D.

1985-03-18

443

Self-expandable transcatheter aortic valve implantation for aortic stenosis after mitral valve surgery  

PubMed Central

OBJECTIVES Transcatheter aortic valve implantation has emerged as a valuable option to treat patients with symptomatic severe aortic stenosis, who are not being considered for surgery because of significant comorbidities. Concerns exist over treating patients who have previously undergone mitral valve surgery for possible interference between the percutaneous aortic valve and the mitral prosthesis or ring. METHODS At our centre, from May 2008 to December 2012, 172 patients (76 male) with severe symptomatic aortic stenosis were eligible for transcatheter aortic valve implant. Nine patients, affected by severe aortic stenosis, had previously undergone mitral valve surgery (4 mono-leaflet, 3 bileaflet, 1 bioprosthesis, 1 mitral ring); they were considered high-risk surgical candidates following joint evaluation by cardiac surgeons and cardiologist and had undergone TAVI. RESULTS Seven patients underwent standard femoral retrograde CoreValve® (Medtronic Inc., Minneapolis, USA) implantation, two patients underwent a direct aortic implantation through a mini-thoracotomy. All patients experienced immediate improvement of their haemodynamic status. No deformation of the nitinol tubing of the CoreValve, nor distortion or malfunction of the mechanical valve or mitral ring, occurred as assessed by echographical and fluoroscopic evaluation. No major postoperative complications occurred. In all patients , echocardiography indicated normal valve function during follow-up. CONCLUSIONS Our experience confirms the feasibility of CoreValve implantation in patients with mechanical mitral valves or mitral annuloplasty ring. PMID:23537849

Bruschi, Giuseppe; De Marco, Federico; Barosi, Alberto; Colombo, Paola; Botta, Luca; Nonini, Sandra; Martinelli, Luigi; Klugmann, Silvio

2013-01-01

444

Risk assessment of drain valve failure in the K-West basin south loadout pit  

SciTech Connect

The drain valve located in the bottom of the K-West Basin South Loadout Pit (SLOP) could provide an additional leak path from the K Basins if the drain valve were damaged during construction, installation, or operation of the cask loading system. For the K-West Basin SLOP the immersion pail support structure (IPSS) has already been installed, but the immersion pail has not been installed in the IPSS. The objective of this analysis is to evaluate the risk of damaging the drain valve during the remaining installation activities or operation of the cask loading system. Valve damage, as used in this analysis, does not necessarily imply large amounts of the water will be released quickly from the basin, rather valve damage implies that the valve's integrity has been compromised. The analysis process is a risk-based uncertainty analysis where best engineering judgement is used to represent each variable in the analysis. The uncertainty associated with each variable is represented by a probability distribution. The uncertainty is propagated through the analysis by Monte Carlo convolution techniques. The corresponding results are developed as a probability distribution and the risk is expressed in terms of the corresponding complementary cumulative distribution function (''risk curve''). The total risk is the area under the ''risk curve''. The risk of potentially dropping a cask into or on the IPSS and damaging the drain valve is approximately 1 x 10{sup -4} to 2 x 10{sup -5} per year. The risk of objects falling behind the IPSS and damaging the valve is 3 x 10{sup -2} to 6 x 10{sup -3} per year. Both risks are expressed as drain value failure frequencies. The risk of objects falling behind the IPSS and damaging the valve can be significantly reduced by an impact limiter and/or installing a gating or plate over the area bounded by the back of the IPSS and the wall of the SLOP. With either of these actions there is a 90 percent confidence that the frequency of drain valve failure would be less than 1 x 10{sup -6} per year.

MORGAN, R.G.

1999-06-23

445

Optimization of multi-valve, four cycle engine design - The benefit of five-valve technology  

SciTech Connect

The multi-valve four stroke cycle engine design trend is toward increased engine power and higher fuel efficiency. While a four-valve system is the most common direction, problems occur when the valve area is widened by increasing the cylinder bore for a higher engine output. The layout for four larger valves causes the combustion chamber shape to flatten and the combustion time period to increase. In pursuit of the optimum multi-valve engine we have studied four, five, six and seven-valve per cylinder design. Performance targets and design constraints led toward the successful five-valve engine technology. This technology develops high engine torque and efficient combustion over a wide range of engine speeds.

Aoi, K.; Nomura, K.; Matsuzaka, H.

1986-01-01

446

An evaluation of the effects of valve body erosion on motor-operated valve operability  

SciTech Connect

INEL engineers evaluated effects of erosion-induced valve wall thinning on motor-operated valve operability. The authors reviewed reports that identified the extent and location of erosion damage in nuclear plant valves and chose a globe valve with severe erosion damage to assess the potential for loss of operability. They developed a finite element model of the selected valve and performed structural analyses with valve closing forces, seismic effects, and increased erosion areas to analyze effects of erosion on structural integrity. Results indicate that while some local stresses at the points of maximum erosion exceeded yield, the general stresses were well below yield. Therefore, displacements will be small and bending will not occur. It is concluded that erosion-related wall thinning is not likely to create an operability problem for motor-operated valves.

Hunt, T.H.; Nitzel, M.E.; Weidenhamer, G.H.

1995-12-01

447

The Melody® valve and Ensemble® delivery system for transcatheter pulmonary valve replacement  

PubMed Central

The Melody® transcatheter pulmonary valve (TPV) is a percutaneous valve system designed for the treatment of obstruction and/or regurgitation of prosthetic conduits placed between the right ventricle and pulmonary arteries in patients with congenital heart disease. In 2000, Melody TPV became the first transcatheter valve implanted in a human; in 2006 it became the first transcatheter valve commercially available anywhere in the world; and in 2010 it was launched as the first commercially available transcatheter valve in the United States. In this review, we present the clinical background against which the Melody valve was developed and implemented, introduce the rationale for and challenges of transcatheter valve technology for this population, outline the history and technical details of its development and use, and summarize currently available data concerning the performance of the device. PMID:23834411

McElhinney, Doff B; Hennesen, Jill T

2013-01-01

448

Training attentional control in older adults.  

PubMed

Recent research has demonstrated benefits for older adults from training attentional control using a variable priority strategy, but the construct validity of the training task and the degree to which benefits of training transfer to other contexts are unclear. The goal of this study was to characterize baseline performance on the training task in a sample of 105 healthy older adults and to test for transfer of training in a subset (n?=?21). Training gains after 5 days and extent of transfer was compared to another subset (n?=?20) that served as a control group. Baseline performance on the training task was characterized by a two-factor model of working memory and processing speed. Processing speed correlated with the training task. Training gains in speed and accuracy were reliable and robust (ps <.001, ?(2)?=?.57 to .90). Transfer to an analogous task was observed (ps <.05, ?(2)?=?.10 to .17). The beneficial effect of training did not translate to improved performance on related measures of processing speed. This study highlights the robust effect of training and transfer to a similar context using a variable priority training task. Although processing speed is an important aspect of the training task, training benefit is either related to an untested aspect of the training task or transfer of training is limited to the training context. PMID:21728889

Mackay-Brandt, Anna

2011-07-01

449

Homograft replacement of the mitral valve  

Microsoft Academic Search

Because of experience gained in reconstructive mitral valve surgery, we have reevaluated the implantation of cryopreserved homografts in the mitral position. Forty-three patients, aged 11 to 69 years (mean 34 years), underwent mitral valve replacement with cryopreserved mitral homografts. The indications for the procedure were acute endocarditis (n = 14), rheumatic stenosis (n = 26), systemic lupus endocarditis (n =

Christophe Acar; Michael Tolan; Alain Berrebi; Jullien Gaer; Roger Gouezo; Thierry Marchix; Jean Gerota; Sylvain Chauvaud; Jean-Noel Fabiani; Alain Deloche; Alain Carpentier

1996-01-01

450

Loss measurement in high voltage thyristor valves  

Microsoft Academic Search

No measuring method is presently available for direct and sufficiently accurate evaluation of power losses in thyristor valves used in HVDC converter stations and Static VAR controllers. This paper presents a measuring method to be used during the valve type tests with the intention to verify the guaranteed loss characteristic. The method was validated under laboratory conditions by comparison to

M. Cepek; J. Douville; G. Fecteau; R. Malewski

1994-01-01

451

Technology trends for HVDC thyristor valves  

Microsoft Academic Search

The worldwide trend in the evolution of high voltage thyristor valves is reviewed, using HVDC applications as an example. The key technologies involved are identified. It is shown that the move towards direct light triggered thyristors (LTT) is but the most recent step in a continuous effort to simplify high voltage thyristor valve technology and make it inherently more reliable

H. Peter Lips

1998-01-01

452

[Cardiac valve replacement in the elderly].  

PubMed

From January 1980 through December 1990, seventy one consecutive patients over 60 years of age (mean age 64 +/- 4 years) and 231 patients younger than 60 years underwent cardiac valve replacement procedures. In the elderly group, aortic valve replacement was performed in nineteen patients, mitral valve replacement in thirty-three patients both aortic and mitral valve replacement in sixteen patients, and both mitral and tricuspid valve replacement in three patients. Aortocoronary bypass was performed in four and tricuspid annuloplasty in 19 patients simultaneously. Two patients were operated on emergency. As for preoperative status, 63 patients (88.7%) were in New York Heart Association (NYHA) Functional Class III or IV. Mechanical valves were implanted in all aortic position and 16 mitral position. Bioprosthetic valves were placed in 34 mitral position and 3 tricuspid position. Mean follow-up period was 42 +/- 33 months. The early mortality rate was 11% (8 patients) and the actuarial survival rate was 88 +/- 5% at five years and 74 +/- 10% at ten years. Postoperative functional improvement was excellent in 85.7% of the survivors. In the younger age group, 77.9% belonged to NYHA class III or IV preoperatively. The early mortality was 3.0% (7 patients) and the actuarial survival rate was 95 +/- 2% at five years and 86 +/- 2% at ten years. And postoperatively 91.3% were in NYHA class I or II. In conclusion, cardiac valve replacement in the elderly can be performed with an acceptable mortality and excellent functional improvement. PMID:1434249

Misawa, Y; Hasegewa, T; Kato, M

1992-10-01

453

Numerical Analysis of Large Diameter Butterfly Valve  

NASA Astrophysics Data System (ADS)

In this paper, a butterfly valve with the diameter of 1,800 mm was studied. Three-dimensional numerical technique by using commercial code CFX were conducted to observe the flow patterns and to measure flow coefficient, hydrodynamic torque coefficient and so on, when the large butterfly valve operated with various angles and uniform incoming velocity.

Youngchul, Park; Xueguan, Song

454

Mitral valve replacement on a beating heart.  

PubMed

We report the case of a patient who needed mitral valve replacement but was at a high risk of myocardial injury with the conventional technique (cardioplegic arrest on cardiopulmonary bypass). Valve replacement was carried out on a beating heart on cardiopulmonary bypass by perfusing the heart continuously with oxygenated noncardioplegic normothermic blood via the coronary sinus. PMID:14686670

Bedi, Harinder S; Singh, Raman P; Goel, Vipin; Lal, Purshottam

2003-01-01

455

Titanium engine valve and method of making  

Microsoft Academic Search

This patent describes a method of making a dual microstructure titanium based engine valve. A first zone of the valve contains essentially a mixture of fine, equiaxed alpha and transformed beta crystalline grains which exhibit high tensile strength and high fatigue resistance. A second zone contains essentially colony type alpha\\/beta crystalline grains exhibiting resistance to high temperature creep, the method

Allison

1987-01-01

456

Heart Valve Disease James S. Gammie, MD  

E-print Network

STENOSIS #12;Normal Anatomy Mitral Stenosis #12;Mitral StenosisNormal #12;Symptoms of Heart Valve DiseaseHeart Valve Disease James S. Gammie, MD Professor and Chief Division of Cardiac Surgery University USA Source: CDC #12;#12;CARDIOTHORACIC SURGEON: A SURGEON THAT TREATS HEART AND LUNG DISEASE #12

Weber, David J.

457

Rotary valve for internal combustion engine  

Microsoft Academic Search

This patent describes a rotary valve apparatus for a cylinder of an internal combustion engine, the cylinder having therein a piston, with the cylinder and the piston defining a combustion chamber at one end of the cylinder and the combustion chamber having an opening thereinto opposite the piston. It comprises a valve housing positioned to cover the opening of the

Buelna

1991-01-01

458

Temperature responsive valve withstands high impact loading  

NASA Technical Reports Server (NTRS)

Valve regulates the flow of a reactant to a chemical heater used in a space application and withstands extreme impact loading. The valve has an upper and a lower housing, the lower containing an inlet and an outlet port, and upper containing a cavity.

Gram, M. B.

1967-01-01

459

Giant magnetoresistance in organic spin-valves  

Microsoft Academic Search

A spin valve is a layered structure of magnetic and non-magnetic (spacer) materials whose electrical resistance depends on the spin state of electrons passing through the device and so can be controlled by an external magnetic field. The discoveries of giant magnetoresistance and tunnelling magnetoresistance in metallic spin valves have revolutionized applications such as magnetic recording and memory, and launched

Z. H. Xiong; Di Wu; Z. Valy Vardeny; Jing Shi

2004-01-01

460

Frostless heat pump having thermal expansion valves  

Microsoft Academic Search

A heat pump system having an operable relationship for transferring heat between an exterior atmosphere and an interior atmosphere via a fluid refrigerant and further having a compressor, an interior heat exchanger, an exterior heat exchanger, a heat pump reversing valve, an accumulator, a thermal expansion valve having a remote sensing bulb disposed in heat transferable contact with the refrigerant

Fang C. Chen; Viung C. Mei

2002-01-01

461

Well packer with by-pass valve  

Microsoft Academic Search

A well packer and bypass valve combination for use in a well bore includes the following components: a mandrel releasably connected to and extending through the packer; a port extending through the mandrel relatively above the packer; and a port closure member slidably mounted on the mandrel above the packer and cooperable with the packer whereby the valve closure member

Kilgore

1968-01-01

462

Less invasive techniques for mitral valve surgery  

Microsoft Academic Search

Objective: Minimally invasive surgical techniques aim at reducing the consequences of currently used large incisions, such as bleeding, pain, and risk of infection. Although this new approach developed rapidly in coronary surgery, it remains questionable in mitral valve surgery. This article reports the longest experience with minimally invasive mitral valve surgery, with particular attention to approach and techniques. Methods: From

Didier F. Loulmet; Alain Carpentier; Peter W. Cho; Alain Berrebi; Nicola d'Attellis; Conal B. Austin; Jean-Paul Couëtil; Paul Lajos

1998-01-01

463

Mitral valve repair in patients over  

Microsoft Academic Search

The question of whether to repair or replace the mitral valve in the elderly remains unanswered. The purpose of our study is to describe our experience with mitral valve repair (MVR) using Carpentier's technique in patients 70 years and older. Fifty consecutive patients underwent MVR between 1984-1992. There were 30 female patients. All had 2 + or more mitral regurgitation

H. Azar; S. Szentpetery

2009-01-01

464

Micromagnetics of spin valve memory cells  

Microsoft Academic Search

This paper presents a systematic micromagnetic analysis on spin valve GMR memory elements. It is found that for submicron size spin valve elements, edge demagnetization field, arising from the pinned layer, results in significant magnetization curling at the end edges of the free layer. This edge demagnetization phenomenon yields significant degradation of device performance. It is proposed that by making

Youfeng Zheng; Jian-Gang Zhu

1996-01-01

465

Surgical treatment of prosthetic valve endocarditis  

Microsoft Academic Search

From 1975 through 1992, we reoperated on 146 patients for the treatment of prosthetic valve endocarditis. Prosthetic valve endocarditis was considered to be early (<1 year after operation) in 46 cases and active in 103 cases. The extent of the infection was prosthesis only in 66 patients, anulus in 46, and cardiac invasion in 34. Surgical techniques evolved in the

Bruce W. Lytle; Brian P. Priest; Paul C. Taylor; Floyd D. Loop; Shelley K. Sapp; Robert W. Stewart; Patrick M. McCarthy; Derek Muehrcke; Delos M. Cosgrove

1996-01-01

466

[Aortic valve reconstruction of aortic root repair].  

PubMed

We report the choice of aortic valve reconstruction, surgical results and postoperative results in 22 patients who underwent aortic root replacement between June 1996 and October 1999. We chose the replacement using bio-prosthesis in six patients over 65 years of age and valve preservation or replacement using mechanical prosthesis in sixteen patients under 65 years of age. Ten patients underwent valve replacement using mechanical prosthesis. There was one hospital death and one late death. Six patients underwent valve replacement using bio-prosthesis. There was no hospital death and no late death. Six patients underwent valve preservation. There was one hospital death. There was no event among five patients in the mid-term follow-up, although a longer follow-up must be necessary. PMID:10770063

Nakano, H; Takahara, Y; Sudoh, Y; Niizuma, Y

2000-04-01

467

Comments on compressible flow through butterfly valves  

NASA Astrophysics Data System (ADS)

In the flow analysis of process piping systems, it is desirable to treat control valves in the same way as elbow, reducers, expansions, and other pressure loss elements. In a recently reported research program, the compressible flow characteristics of butterfly valves were investigated. Fisher Controls International, Inc., manufacturer of a wide range of control valves, publishes coefficients that can be used to calculate flow characteristics for the full range of valve movement. The use is described of the manufacturer's data to calculate flow parameters as reported by the researchers who investigated compressible flow through butterfly valves. The manufacturer's data produced consistent results and can be used to predict choked flow and the pressure loss for unchoked flow.

Blakenship, John G.

468

Comments on compressible flow through butterfly valves  

SciTech Connect

In the flow analysis of process piping systems, it is desirable to treat control valves in the same way as elbow, reducers, expansions, and other pressure loss elements. In a recently reported research program, the compressible flow characteristics of butterfly valves were investigated. Fisher Controls International, Inc., manufacturer of a wide range of control valves, publishes coefficients that can be used to calculate flow characteristics for the full range of valve movement. This paper describes the use of the manufacturer's data to calculate flow parameters as reported by the researchers who investigated compressible flow through butterfly valves. The manufacturer's data produced consistent results and can be used to predict choked flow and the pressure loss for unchoked flow. 4 refs., 6 figs., 1 tab.

Blakenship, J.G. (Oak Ridge Gaseous Diffusion Plant, TN (USA))

1989-01-01

469

Physical Fitness Training  

Microsoft Academic Search

An evaluation of a program designed to enhance self concept, reduce muscular tension and alleviate feelings of helplessness and depression was presented. Results indicated that physical fitness training alone may be as effective as relaxation on the aforementioned variables. Additionally, a combination of both treatments may not be as effective as either single treatment programs. Suggestions are given as to

Frank A. De Piano; Linda C. De Piano; Wayne Carter; Richard L. Wanlass

1984-01-01

470

Three-dimensional printed trileaflet valve conduits using biological hydrogels and human valve interstitial cells.  

PubMed

Tissue engineering has great potential to provide a functional de novo living valve replacement, capable of integration with host tissue and growth. Among various valve conduit fabrication techniques, three-dimensional (3-D) bioprinting enables deposition of cells and hydrogels into 3-D constructs with anatomical geometry and heterogeneous mechanical properties. Successful translation of this approach, however, is constrained by the dearth of printable and biocompatible hydrogel materials. Furthermore, it is not known how human valve cells respond to these printed environments. In this study, 3-D printable formulations of hybrid hydrogels are developed, based on methacrylated hyaluronic acid (Me-HA) and methacrylated gelatin (Me-Gel), and used to bioprint heart valve conduits containing encapsulated human aortic valvular interstitial cells (HAVIC). Increasing Me-Gel concentration resulted in lower stiffness and higher viscosity, facilitated cell spreading, and better maintained HAVIC fibroblastic phenotype. Bioprinting accuracy was dependent upon the relative concentrations of Me-Gel and Me-HA, but when optimized enabled the fabrication of a trileaflet valve shape accurate to the original design. HAVIC encapsulated within bioprinted heart valves maintained high viability, and remodeled the initial matrix by depositing collagen and glyosaminoglycans. These findings represent the first rational design of bioprinted trileaflet valve hydrogels that regulate encapsulated human VIC behavior. The use of anatomically accurate living valve scaffolds through bioprinting may accelerate understanding of physiological valve cell interactions and progress towards de novo living valve replacements. PMID:24334142

Duan, B; Kapetanovic, E; Hockaday, L A; Butcher, J T

2014-05-01

471

Relationship between off-ice testing variables and on-ice speed in women's collegiate synchronized figure skaters: implications for training.  

PubMed

The purpose of the current investigation was to identify any existing relationships between off-ice performance measures and on-ice performance quantified by speed and acceleration. Twenty-seven women (age 19 +/- 1 year; body mass (59.5 +/- 6.8 kg; height 164.6 +/- 6.35 cm; body fat 23.2 +/- 3.9%) who were collegiate synchronized figure skaters volunteered for the investigation. To examine the relationship between off-ice performance and on-ice speed and acceleration, collegiate synchronized skaters were evaluated on various performance tests over a 1-week period. Off-ice tests completed were peak torque for hip abduction and adduction, 40-yard sprint, vertical jump height, 30-second slide board stride count, and a 1-RM (repetition maximum) squat. On-ice tests included a timed single lap sprint, 4.5-minute (duration of long program) lap count, and an approximately 16.5-m (18-yard blue line to blue line) timed acceleration. Significance was set at P < or = 0.05. This study showed 3 primary findings: (a) slide board stride count was the single best predictor for both single lap on-ice speed and acceleration accounting for 53.5% (adjusted R2 value) of the variance in the single lap test and 42.5% (adjusted R2 value) of the variance in acceleration times; (b) vertical jump height test was the second best predictor for both the single lap test and on-ice acceleration accounting for 36.6% and 39.9% (adjusted R2 values) of the variance in times recorded, respectively; and (c) the best combined predictors for the single lap speed test were slide board stride count and 40-yard dash (R2 = 0.675), whereas the best combined predictors for on-ice acceleration were slide board stride count and vertical jump height test (R2 = 0.571). Conditioning for synchronized skaters to enhance performance of on-the-ice speed and acceleration should include slide board training implementation of plyometric and linear speed training while developing and maintaining 1-RM strength to support power capabilities. PMID:19816217

Bower, Michelle E; Kraemer, William J; Potteiger, Jeffrey A; Volek, Jeff S; Hatfield, Disa A; Vingren, Jakob L; Spiering, Barry A; Fragala, Maren S; Ho, Jen-Yu; Thomas, Gwendolyn A; Earp, Jacob E; Häkkinen, Keijo; Maresh, Carl M

2010-03-01

472

A thin film nitinol heart valve.  

PubMed

In order to create a less thrombogenic heart valve with improved longevity, a prosthetic heart valve was developed using thin film nitinol (NiTi). A "butterfly" valve was constructed using a single, elliptical piece of thin film NiTi and a scaffold made from Teflon tubing and NiTi wire. Flow tests and pressure readings across the valve were performed in vitro in a pulsatile flow loop. Bio-corrosion experiments were conducted on untreated and passivated thin film nitinol. To determine the material's in vivo biocompatibility, thin film nitinol was implanted in pigs using stents covered with thin film NiTi. Flow rates and pressure tracings across the valve were comparable to those through a commercially available 19 mm Perimount Edwards tissue valve. No signs of corrosion were present on thin film nitinol samples after immersion in Hank's solution for one month. Finally, organ and tissue samples explanted from four pigs at 2, 3, 4, and 6 weeks after thin film NiTi implantation appeared without disease, and the thin film nitinol itself was without thrombus formation. Although long term testing is still necessary, thin film NiTi may be very well suited for use in artificial heart valves. PMID:16438227

Stepan, Lenka L; Levi, Daniel S; Carman, Gregory P

2005-11-01

473

Magnetic resonance imaging of prosthetic heart valves.  

PubMed

To evaluate the safety of magnetic resonance (MR) imaging of prosthetic heart valves, nine different synthetic and tissue valves were studied ex vivo. Deflection was measured in 0.35-tesla (T) and 1.5-T superconducting magnets and at the edge of the bore of a 2.35-T electromagnet in field gradients of 5, 1.1, and 6.3 mT/cm, respectively. No valve deflected in the 0.35-T magnet; six synthetic valves deflected 0.25 degrees-3 degrees in the 1.5-T magnet; all valves deflected 1 degree-27 degrees at the edge of the 2.35-T magnet. Each valve was then submerged in a vial of water and the temperature was measured immediately before and after each of two spin-echo imaging sequences in the two superconducting magnets. No significant temperature rise followed exposure in either magnet. Image distortion varied from negligible to severe in both imagers; magnitude of distortion paralleled magnitude of deflection. These data suggest that patients with present-day prosthetic heart valves can be safely imaged in present-day MR imagers and that prosthesis-induced artifacts will not interfere with interpretation in most instances. PMID:3969474

Soulen, R L; Budinger, T F; Higgins, C B

1985-03-01

474

'Fast-implantable' aortic valve implantation and concomitant mitral procedures.  

PubMed

Concomitant aortic and mitral valve replacement or concomitant aortic valve replacement and mitral repair can be a challenge for the cardiac surgeon: in particular, because of their structure and design, two bioprosthetic heart valves or an aortic valve prosthesis and a rigid mitral ring can interfere at the level of the mitroaortic junction. Therefore, when a mitral bioprosthesis or a rigid mitral ring is already in place and a surgical aortic valve replacement becomes necessary, or when older high-risk patients require concomitant mitral and aortic procedures, the new 'fast-implantable' aortic valve system (Intuity™ valve, Edwards Lifesciences, Irvine, CA, USA) can represent a smart alternative to standard aortic bioprosthesis. Unfortunately, this is still controversial (risk of interference). However, transcatheter aortic valve replacements have been performed in patients with previously implanted mitral valves or mitral rings. Interestingly, we learned that there is no interference (or not significant interference) among the standard valve and the stent valve. Consequently, we can assume that a fast-implantable valve can also be safely placed next to a biological mitral valve or next to a rigid mitral ring without risks of distortion, malpositioning, high gradient or paravalvular leak. This paper describes two cases: a concomitant Intuity™ aortic valve and bioprosthetic mitral valve implantation and a concomitant Intuity™ aortic valve and mitral ring implantation. PMID:25015540

Ferrari, Enrico; Siniscalchi, Giuseppe; Marinakis, Sotirios; Berdajs, Denis; von Segesser, Ludwig

2014-07-11

475

Whitey SCHe Ball Valves Provide Test Port Isolation  

SciTech Connect

These valves are 1/4-inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as normally closed isolation valves for test ports in the SCHe System between the gage root valve and the pressure indicator.

MISKA, C.R.

2000-10-19

476

Control and protection of HVDC systems with diode valve converter  

Microsoft Academic Search

A HVDC transmission line carrying electric power from power plants in remote areas to urban areas transmits electric power always in the same direction. In such a case, the thyristor valves at the rectifier station can be replaced by diode valves. Although diode valves are less expensive than thyristor valves, the former may be inferior to the latter from viewpoints

Takehiko Machida; Iwao Ishikawa; Etsuji Okada; Eiichi Karasawa

1978-01-01

477

Calculation of overvoltage distribution in HVDC thyristor valves  

Microsoft Academic Search

Thyristor valves are the core components in HVDC transmission system. These valves in the system are exposed to various overvoltages both external and internal. So it is important to analyze the characteristic of the converter valves under different overvoltages. Wide-band equivalent circuits of the valve components such as thyristor, saturable reactor are obtained based on impedance measurement. And stray capacitances

Haifeng Sun; Xiang Cui; Lei Qi; Qi Wang

2010-01-01

478

Design of a High-Efficiency Magnetorheological Valve  

Microsoft Academic Search

A high efficiency design was explored for meso-scale magnetorheological (MR) valves (< 25 mm OD with an annular gap < 1 mm). The objective of this paper is to miniaturize the MR valve while maintaining the maximum performance of the MR effect in the valve. The main design issues in the MR valve involve the magnetic circuit and nonlinear fluid

Jin-Hyeong Yoo; Norman M. Wereley

2002-01-01

479

Method of Manufacturing Carbon Fiber Reinforced Carbon Composite Valves  

NASA Technical Reports Server (NTRS)

A method for forming a carbon composite valve for internal combustion engines is discussed. The process includes the steps of braiding carbon fiber into a rope thereby forming a cylindrically shaped valve stem portion and continuing to braid said fiber while introducing into the braiding carbon fiber rope a carbon matrix plug having an outer surface in a net shape of a valve head thereby forming a valve head portion. The said carbon matrix plug acting as a mandrel over which said carbon fiber rope is braided, said carbon fiber rope and carbon matrix plug forming a valve head portion suitable for mating with a valve seat; cutting said braided carbon valve stem portion at one end to form a valve tip and cutting said braided carbon fiber after said valve head portion to form a valve face and thus provide a composite valve preform; and densifying said preform by embedding the braided carbon in a matrix of carbon to convert said valve stem portion to a valve stem and said valve head portion to a valve head thereby providing said composite valve.

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

1998-01-01

480

Biomechanics of the pulmonary autograft valve in the aortic position.  

PubMed

Pulmonary autograft valve replacement has been simulated by implanting the pulmonary valve into the aortic position of the same cadaver heart from both human and porcine sources. The forces acting on the pulmonary valve leaflets have been calculated on the basis of a triaxial ellipsoid mathematical model. These forces on the pulmonary autograft valve were shown to be essentially similar to those previously reported for aortic valve leaflets. Biomechanical measurements have been made on the simulated autograft valves and on the isolated pulmonary valve cusps. The tensile strengths of the pulmonary valve cusps in both circumferential and radial directions were roughly three times greater than those of aortic valve cusps. This indicated the ability of the pulmonary valves to accept, ab initio, aortic valve closing pressures. Pressure-induced changes in dimension, calculated on the basis of diameters of the simulated pulmonary autograft root, also indicated that the distensibility of the autograft valve was limited. It reached a maximum at 30 mm Hg (4 kPa) without any suggestion of further distension to the point of distortion and incompetence. The combination of the calculated forces acting on the valve and the biomechanical measurements have shown that pulmonary valves used as autograft aortic valve replacements are able to tolerate aortic pressures from the time of implantation. These experimental results from simulated autografts support the clinical use of this valve over the past 13 years. PMID:7135295

Gorczynski, A; Trenkner, M; Anisimowicz, L; Gutkowski, R; Drapella, A; Kwiatkowska, E; Dobke, M

1982-07-01

481

Hydraulic valve control system for internal combustion engines  

Microsoft Academic Search

This patent describes a hydraulic engine valve actuating assembly for use in an internal combustion engine cylinder head having a poppet valve which is axially shiftable therein by a rotary camshaft, the hydraulic engine valve actuating assembly. It comprises a housing having a mounted surface to attach to the cylinder head immediately above the poppet valve, a master piston cooperating

T. J. Bowman; J. A. LoRusso; W. F. Kaufman

1992-01-01

482

Valve operation stopping means for multi-cylinder engine  

Microsoft Academic Search

This patent describes a valve operating mechanism for multi-cylinder internal combustion engine including a cam shaft with cams formed integrally with the cam shaft at positions corresponding to suction valves and exhaust valves for each cylinder, a valve operation stopping device comprising a drive rocker arm engaging one of the cams, a driven rocker arm engaging one of either the

Nagahiro

1986-01-01

483

Three-dimensional analysis of partially open butterfly valve flows  

Microsoft Academic Search

A numerical simulation of butterfly valve flows is a useful technique to investigate the physical phenomena of the flow field. A three-dimensional numerical analysis was carried out on incompressible fluid flows in a butterfly valve by using FLUENT, which solves difference equations. Characteristics of the butterfly valve flows at different valve disk angles with a uniform incoming velocity were investigated.

Chendong Huang; Rhyn H. Kim

1996-01-01

484

Inexpensive thermally operated valve for automatic liquid nitrogen refill systems  

Microsoft Academic Search

The thermally actuated valve described is intended for use as an exhaust control valve in conventional liquid nitrogen automatic refill systems. The valve is of a very simple and purely mechanical construction, and is operated directly by the difference in thermal expansion between an inner rod of copper-stainless steel and an outer tube of Pyrex. The valve will keep the

R S Sigmond

1965-01-01

485

Mitral valve repair in children using Carpentier's techniques  

Microsoft Academic Search

Controversy remains regarding whether valve repair is preferable to valve replacement in children suffering from rheumatic mitral valve disease. To answer this question, 130 children aged 3 to 15 years (mean age, 11.8 ± 2.8 years) undergoing surgery between January 1992 and December 1997 using Carpentier's techniques were reviewed. There were 111 cases of rheumatic valve diseases (85%), 17 cases

Kim Phuong Phan; van Phan Nguyen; Nguyen Vinh Pham; Huu Trung Dao; thi Thuy Anh Dang; Huu Dung Le; Trong Hiep Chu; Huynh Quang Tri Ho; Alain Carpentier

1999-01-01

486