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1

Adaptive torque demand control of SI engine with a continuous variable valve train  

Microsoft Academic Search

In recent years, integrated vehicle control system has been designed based on the information of torque. Therefore, engine is teated as the actuator generating torque and necessity of controlling engine torque has been increased. This paper describes adaptive torque demand control of SI (Spark Ignition) engine with continuous variable valve lift which is based on STC (Self Tuning Control).

S. Sugihira; N. Sato; H. Ohmori

2009-01-01

2

Variable orifice gas modulating valve  

SciTech Connect

An automatic gas modulating valve is described for regulating the flow of gaseous fuel from a fuel source to a gas burner, comprising a first valve body member; a second valve body member fixed to the first valve body member so as to define a relatively thin planar slide cavity between the first valve body member and the second valve body member; circular grooves cut into said first and second planar surfaces, each groove cut to a depth to accommodate two stacked O-rings such that the top portion of the top O-ring protrudes slightly above the planar surface; a pair of O-rings set into each of said grooves, the bottom O-ring being of a deformable material and the top O-rings being of a harder material that offers a low coefficient of sliding friction against a metal surface; a moveable slide which is slightly thinner than the width of said thin planar slide cavity, having an opening formed therein, such that the top O-rings of the said pairs of O-rings form face seals on the opposite sides of the slide and the bottom O-rings of the said pairs are deformed so as to provide sufficient normal force to effect the face seals, thereby minimizing gas leakage from the valve, said slide being moveable back and forth within the planar slide cavity, the opening of the slide being interposed between the inlet and outlet ports such that the sliding motion of the slide varies the position of the slide opening relative to the inlet and outlet ports so as to form a variable orifice within the gas discharge passageway, whereby the flow of gas from the source to the burner is modulated and controlled by the sliding movement of the slide; means to constrain the movement of the slide between two extreme positions; an automatic actuator, whereby automatic modulating control of the gas flow may be effected; and connecting means connected between the actuator and the slide for sliding the slide back and forth in response to the actuator.

Harris, J.A.

1993-08-10

3

Training aids: the motor operator valve trainer  

Microsoft Academic Search

The spectrum of training aids used in the nuclear industry runs the gamut from the very basic (i.e., valve training aids - gate, globe, check) to the highly complex (i.e., nuclear full scope simulator). Designing and purchasing the best training aids take much time, detailed investigation, and good understanding of plant operations. The training aid that has given the New

McCulloch

1987-01-01

4

Multistage variable area throttle valve  

Microsoft Academic Search

A throttle or fluid control valve uses at least one compressible multi-wave washer as a fluid control element. The apertures formed by the multi-wave washer are short and of low aspect ratio when the valve is fully open to limit pressure drop across the valve, thus substantially preventing cavitation and flow related noise to high flow velocities. As the valve

Mark E. Shiffler; Joseph H. Morris

1995-01-01

5

A new electromagnetic engine valve actuator with less energy consumption for variable valve timing  

Microsoft Academic Search

A variable valve timing (VVT) can improve fuel efficiency, reduce CO2 emissions and increase torque output enabling optimization\\u000a of these outputs at different engine conditions. To achieve VVT in internal combustion engine, new devices such as mechanical,\\u000a hydraulic, motor-driven and electromagnetic actuators have been developed in past years to replace the conventional camshaft\\u000a valve train system used currently. Among these,

Jinho Kim; Dennis K. Lieu

2007-01-01

6

Multistage variable area throttle valve  

NASA Astrophysics Data System (ADS)

A throttle or fluid control valve uses at least one compressible multi-wave washer as a fluid control element. The apertures formed by the multi-wave washer are short and of low aspect ratio when the valve is fully open to limit pressure drop across the valve, thus substantially preventing cavitation and flow related noise to high flow velocities. As the valve is closed, the aspect ratio of the apertures increases but surfaces of the apertures remain angled to each other to provide noise cancellation and damping. Several multi-wave washers spaced by sliders are preferably used to further limit pressure drop in any stage and to form a serpentine path in the general direction of flow to provide further noise cancellation and damping. The sliders also enhance the self purging action of the valve structure. A closure structure is also provided for assuring full closure of the valve.

Shiffler, Mark E.; Morris, Joseph H.

1995-05-01

7

Turbo-generator control with variable valve actuation  

Microsoft Academic Search

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

Vuk; Carl T

2011-01-01

8

Modeling and control of a variable valve timing engine  

Microsoft Academic Search

A cylinder-by-cylinder model of an experimental variable valve timing 4-cylinder engine has been developed. The model includes the cylinder and manifold mass, temperature, burned gas residual, and pressure dynamics, including combustion effects, as well as the valve actuator dynamics. The cylinder-by-cylinder model is used to obtain a cycle-averaged mapping between torque at a given engine speed and intake valve timing,

Lawrence Mianzo; Huoi Peng

2000-01-01

9

Engine having a variable valve actuation system  

Microsoft Academic Search

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

Hefler; Gregory W

2004-01-01

10

Engine having a variable valve actuation system  

Microsoft Academic Search

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

Hefler; Gregory W

2005-01-01

11

Variable Reluctance Proximity Sensors for Cryogenic Valve Position Indication.  

National Technical Information Service (NTIS)

A test was conducted to determine the performance of a variable reluctance proximity sensor system when installed in a space shuttle external tank vent/relief valve. The sensors were used as position indicators. The valve and sensors were cycled through a...

R. A. Cloyd

1982-01-01

12

Study of fluid flow and combustion with variable valve timing.  

National Technical Information Service (NTIS)

The effects of variable valve timing (VVT) were examined by in-cylinder Laser Doppler Velocimetry flow measurements and heat-release calculations. A single-cylinder Volvo B5254 engine was used for all experiments and the valve timing was altered by phasin...

F. Soederberg

1998-01-01

13

MULTIBODY ANALYSIS OF THE DESMODROMIC VALVE TRAIN OF THE DUCATI MOTOGP ENGINE  

Microsoft Academic Search

This paper presents a preliminary study concerning a multibody model of the des- modromic valve train used in the Ducati MotoGP engines. The desmodromic mechanism has a positive cam that causes the dynamic effects to be partly different from common valve trains, where the valve spring plays an important role. The presented model includes only one cam- valve mechanism. In

David Moreno; Emiliano Mucchi; Giorgio Dalpiaz; Alessandro Rivola

14

Control of Variable Valve Lift Engine by Nonlinear MPC  

NASA Astrophysics Data System (ADS)

In this study, we purpose a control system of engine torque for a V6 spark ignition engine with a variable valve lift system. We apply a nonlinear receding horizon control to a benchmark problem where we assume that the control inputs are throttle angle, variable valve lift and ignition timing. Moreover, a fuel injection control is also developed by estimating the amount of air in the engine. We propose a vehicle speed tracking control by defining time derivative of input as new input and dealing with input constraint by transformation of input variables. Finally, we show some numerical simulation results to verify the proposed methods.

Murayama, Akihiro; Yamakita, Masaki

15

Continuously variable mixing-ratio micromixer with elastomer valves  

NASA Astrophysics Data System (ADS)

We report a self-contained microfluidic alternate flow injection mixer (AFIM) employing piezoelectrically actuated, PDMS seal-valves to control injection. AFIMs employ pulsatile injection of liquids to enhance interface surface generation. By allowing control of pulse-volume proportionality by variation of the duty-cycle of the valve control signals, continuously variable ratio mixing is achieved without external fluid control components. Mixing is discussed in the context of 'rate of new surface generation', thus allowing comparison with laminating mixer designs. The prototype mixer employs a simple micromould fabrication technique to minimize reversible elastomer valve-seal adhesion and hence allow correct valve operation. The resulting device has been characterized over a range of mixing ratios.

Tan, Christabel K. L.; Tracey, Mark C.; Davis, John B.; Johnston, Ian D.

2005-10-01

16

Research on the electro-hydraulic variable valve actuation system based on a three-way proportional reducing valve  

Microsoft Academic Search

As the internal combustion engine moves into the 21st century, fully flexible valve actuation systems are being proposed as\\u000a an enabling technology for advanced internal combustion engine concepts. Electro-hydraulic valve actuator systems are being\\u000a considered as a potential variable valve technology. Compared to the servo control system, the system using a proportional\\u000a valve has the advantages of low price, high

J.-R. Liu; B. Jin; Y.-J. Xie; Y. Chen; Z.-T. Weng

2009-01-01

17

Physically based volumetric efficiency model for diesel engines utilizing variable intake valve actuation  

Microsoft Academic Search

Advanced diesel engine architectures employing flexible valve trains enable emissions reductions and fuel economy improvements. Flexibility in the valve train allows engine designers to optimize the gas exchange process in a manner similar to how common rail fuel injection systems enable optimization of the fuel injection process. Modulating valve timings directly impacts the volumetric efficiency of the engine since it

L Kocher; E Koeberlein; D G Van Alstine; K Stricker; G Shaver

2012-01-01

18

The lubrication of engine valve trains equipped with ceramicized followers  

SciTech Connect

The valve train wear characteristics of motored 2.2l and 2.3l engines were examined using ceramic and conventional metal cam followers. Under regular wear conditions with fully formulated motor oils, minimal wear was observed on the metal cam lobes running with either the ceramicized or metal followers. Running under chemically accelerated wear conditions with low quality oil, however, cam lobe wear with ceramicized followers was observed to be significantly less than that with metal followers. The difference in wear was diminished when testing high quality oils under chemically accelerated conditions. Typical testing revealed that the metal follower pads quickly developed considerable wear in a characteristic pattern, while the ceramic followers pads quickly developed considerable were in a characteristic pattern, while the ceramic followers exhibited only slight polishing. Scanning electron photographs revealed details of the used ceramic surfaces, and that wear took place by polishing and by intergranular fracture with subsequent material removal. Engine wear is a major factor that limits the life of today's passenger cars. Particularly for the newer models that have smaller but higher speed and output engines incorporating current designs such as overhead camshafts, 4-valves per cylinder and turbochargers, the valve train represents one of the highest wear components within an engine. In light of the trend towards extended drivetrain warranties, there is a strong demand for lubricant suppliers to develop engine oils with improved antiwear performance. In a parallel effort, automotive engine and component manufacturers are enhancing valve train durability with technologies that include roller followers and the use of advanced ceramic materials.

Blahey, A.G.; Habeeb, J.J.; Rogers, W.N.< 110> The lubrication of engine valve trains equipped with ceramicized followers.

1990-01-01

19

Investigation of a rotary valving system with variable valve timing for internal combustion engines  

NASA Astrophysics Data System (ADS)

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 multifuel 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, Paul C.; Hansen, Craig N.

1994-11-01

20

Damped vibration of engine valve train by recent transfer matrix and matrix procedures  

NASA Astrophysics Data System (ADS)

Damped vibrations of engine valve systems have been investigated by multiple degree of freedom models and the recent transfer matrix techniques and complex eigenvalue analysis procedures. The numerical results obtained were compared with the other available procedures including an exact continuous model solution. The multiple degree of freedom models were found to be superior, especially, in predicting forces acting on the engine valve train. The present application of the transfer matrix method with recent developments, gives accurate estimation of the vibration characteristics and harmonic response of engine valve trains. Complex matrix method analysis also supports the obtained results.

Karadag, Vedat

1991-05-01

21

A novel electromagnetic latching device for variable valve timing in automotive engine  

Microsoft Academic Search

One of the most promising ways to improve fuel economy, reduce CO2 emissions and increase torque output is to achieve variable valve timing (VVT). Some of the devices developed in the past years include mechanical, hydraulic, motor-driven and electromagnetic actuators. Existing most advanced system is an electromagnetic actuator using solenoids to activate engine valves. It, however, needs the current continuously

Jin-Ho Kim; Joung-Hwan Chang; Se-Myung Park; Ki-Il Hwang; Jae-Yong Lee

2010-01-01

22

Fault diagnosis for diesel valve trains based on time frequency images  

NASA Astrophysics Data System (ADS)

In this paper, the Wigner Ville distributions (WVD) of vibration acceleration signals which were acquired from the cylinder head in eight different states of valve train were calculated and displayed in grey images; and the probabilistic neural networks (PNN) were directly used to classify the time frequency images after the images were normalized. By this way, the fault diagnosis of valve train was transferred to the classification of time frequency images. As there is no need to extract further fault features (such as eigenvalues or symptom parameters) from time frequency distributions before classification, the fault diagnosis process is highly simplified. The experimental results show that the faults of diesel valve trains can be classified accurately by the proposed methods.

Wang, Chengdong; Zhang, Youyun; Zhong, Zhenyuan

2008-11-01

23

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

24

Limit-push training reduces motor variability.  

PubMed

Variability in human motor control has been a long observed phenomenon, which has come to be known by some as repetition without repetition. There are several explanations for this. One such explanation asserts that many equally optimal solutions exist for accomplishing the same task that naturally allows choices in how it can be successfully executed. The aim of this study was to determine whether variability could be conditioned within an invisible subspace, using visual and force feedback. We utilized a novel haptic-graphic boundary-oriented environment to condition motor variability. Subjects reduced the variability of their movements, such that action predominated within a subspace determined apriori; while the untreated group did not. These results show encouraging preliminary evidence that neural rehabilitative haptic-graphic interfaces can condition human motor variability. This type of training may benefit neurologically impaired individuals, who exhibit the commonly seen motor deficits of large trial to trial variability, such as victims of stroke and traumatic brain injury. PMID:22275687

Sharp, Ian; Patton, James L

2011-01-01

25

Flatness-Based Tracking of an Electromechanical Variable Valve Timing Actuator With Disturbance Observer Feedforward Compensation  

Microsoft Academic Search

A comprehensive control strategy for an automotive solenoid variable valve timing actuator is presented that addresses the issues of feedback sensors, soft seating or landing control, disturbance rejection and feedforward design. In particular, the motion control of the engine exhaust valve actuator subject to large cycle-to-cycle gas force variations is successfully demonstrated in simulation and on an experimental test-bench. Also

Ryan R. Chladny; Charles R. Koch

2008-01-01

26

Dynamic feedback linearization of Diesel engines with intake variable valve actuation  

Microsoft Academic Search

In this paper, a nonlinear control technique based on the property of flatness is proposed to control the air system of new generation diesel engines. The simulated engine is equipped with variable valve actuation (VVA), variable geometry turbocharger (VGT) and exhaust gas recirculation (EGR). The control objective is to achieve tracking of suitable references of flat outputs with corresponding intake

A. Plianos; Richard Stobart

2007-01-01

27

Transient torque rise of a modern light duty diesel engine with variable valve actuation  

Microsoft Academic Search

Simulation has been used to investigate how variable duration VVA can influence the transient torque rise of a modern light-duty diesel engine. The base engine examined employed a variable geometry turbo-charger with air to air inter-cooling, cooled EGR and common rail fuel injection. The VVA system investigated was variable duration, applied to both intake and exhaust valves, controlling primarily exhaust

Tim Lancefield

28

Output feedback Parametric Controllers for an Active Valve Train Actuation System  

Microsoft Academic Search

The first commercial camless car engines featuring continuously variable valve timing are expected to be available by 2010 to meet the strict legislation on NOx and COx emissions. A key factor for the development of this technology is the design of controllers that can maintain accurate signal tracking in the presence of variations in engine parameters and running conditions. Towards

V. Kosmidis; A. Panga; V. Sakizlis; G. Charles; S. Kenchington; N. Bozinis; E. N. Pistikopoulos

2006-01-01

29

Study on Modeling of Electro-Hydraulic Variable Valve Mechanism Based on CATIA  

Microsoft Academic Search

This paper describes a modeling method for electro-hydraulic variable valve mechanism based on CATIA. It focuses on the principle of the mechanism and the models of some parts with oil circuits in the hydraulic system and the moving principle of the actuation system. The additional damping cavity is used for pressure compensation. The actual mechanism based on the model precisely

Yanhua Gu; Hua Li; Fafa Liu; Yunkai Wang; Yingnan Guo

2010-01-01

30

Motion planning for experimental air path control of a variable-valve-timing spark ignition engine  

Microsoft Academic Search

Air path control of a spark ignition engine without an EGR loop, equipped with variable-valve-timing (VVT) actuators, is addressed in this paper. VVT devices are used to produce internal exhaust gas recirculation, providing beneficial effects in terms of fuel consumption and pollutant emissions reduction. However, VVT actuators affect the fresh air charge in the cylinders. This has an impact on

Thomas Leroy; Jonathan Chauvin; Nicolas Petit

2009-01-01

31

Airpath control of a SI engine with Variable Valve Timing actuators  

Microsoft Academic Search

We address the control of the airpath of a turbocharged SI engine equipped with variable valve timing (VVT) actuators. VVT devices are used to produce internal exhaust gas recirculation, providing beneficial effects in terms of consumption and pollutant emissions reduction. However, VVT actuators affect the fresh air charge in the cylinders. This has an impact on the torque output (leading

Thomas Leroy; Jonathan Chauvin; Nicolas Petit

2008-01-01

32

Variable valve closure timing for load control and the Otto Atkinson cycle engine  

Microsoft Academic Search

Two fundamental methods of improving the brake specific fuel consumption of a spark ignition engine at part load have been investigated. These comprise the reduction of pumping losses by variable intake valve timing and changes of clearance volume to increase the expansion ratio. The resulting Otto-Atkinson cycle engine competes with the Diesel cycle engine. Test bed results from a four

R. J. Saunders; E. A. Abul-Wahab

1989-01-01

33

Fuel Economy Effects and Incremental Cost, Weight and Lead Time Impacts of Employing Variable Valve Timing (VVT) Engine Technology.  

National Technical Information Service (NTIS)

In recent years, new mechanical inventions and electronic engine controls have made variable valve timing a production possibility. A few manufacturers have VVT systems in production. The report presents a paper study of the fuel economy benefits and the ...

D. Patterson A. Simko D. Reilly

1997-01-01

34

Generation of variable anatomical models for surgical training simulators  

Microsoft Academic Search

The generation of variable surgical scenes is a key element for effective training with surgery simulators. Our current research aims at a high fidelity hysteroscopy simulator which challenges the trainee with a new surgical scene in every training session. We previously reported on methods able to generate a broad range of pathologies within an existing healthy organ model. This paper

Raimundo Sierra; Gabriel Zsemlye; Gábor Székely; Michael Bajka

2006-01-01

35

Blood Pressure Variability and Stress Management Training for Essential Hypertension  

ERIC Educational Resources Information Center

|The purpose of this study was to determine whether stress management training reduces blood pressure (BP) variability in hypertensive patients. Previous literature suggests that cardiovascular risk is not only a function of BP levels, but also of BP variability, and this partially depends on changes induced by the stress of everyday life. The…

Garcia-Vera, Maria Paz; Sanz, Jesus; Labrador, Francisco J.

2004-01-01

36

Variable valve closure timing for load control and the Otto Atkinson cycle engine  

SciTech Connect

Two fundamental methods of improving the brake specific fuel consumption of a spark ignition engine at part load have been investigated. These comprise the reduction of pumping losses by variable intake valve timing and changes of clearance volume to increase the expansion ratio. The resulting Otto-Atkinson cycle engine competes with the Diesel cycle engine. Test bed results from a four cylinder engine are reported which largely confirm previous predictions from thermodynamic cycle simulation. The interactive effects between cylinders on pumping loss and mixture requirements are discussed.

Saunders, R.J.; Abul-Wahab, E.A.

1989-01-01

37

Individualised training to address variability of radiologists' performance  

NASA Astrophysics Data System (ADS)

Computer-based tools are increasingly used for training and the continuing professional development of radiologists. We propose an adaptive training system to support individualised learning in mammography, based on a set of real cases, which are annotated with educational content by experienced breast radiologists. The system has knowledge of the strengths and weakness of each radiologist's performance: each radiologist is assessed to compute a profile showing how they perform on different sets of cases, classified by type of abnormality, breast density, and perceptual difficulty. We also assess variability in cognitive aspects of image perception, classifying errors made by radiologists as errors of search, recognition or decision. This is a novel element in our approach. The profile is used to select cases to present to the radiologist. The intelligent and flexible presentation of these cases distinguishes our system from existing training tools. The training cases are organised and indexed by an ontology we have developed for breast radiologist training, which is consistent with the radiologists' profile. Hence, the training system is able to select appropriate cases to compose an individualised training path, addressing the variability of the radiologists' performance. A substantial part of the system, the ontology has been evaluated on a large number of cases, and the training system is under implementation for further evaluation.

Sun, Shanghua; Taylor, Paul; Wilkinson, Louise; Khoo, Lisanne

2008-04-01

38

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

39

Safety and efficiency assessment of training Canadian cardiac surgery residents to perform aortic valve surgery  

PubMed Central

Background Research has demonstrated equivalent patient safety outcomes for various cardiac procedures when the primary surgeon was a supervised trainee. However, cardiac surgery cases have become more complex, and the Canadian cardiac surgery education model has undergone some changes. We sought to compare patient safety and efficiency of aortic valve replacement (AVR) between Canadian patients treated by senior cardiac trainees and those treated by certified cardiac surgeons. Methods We completed a single-centre, case-matched, prospectively collected and retrospectively analyzed study of AVR. Patients were matched between trainees and consultants for age, sex, New York Heart Association and Canadian Cardiovascular Society status, urgency of operation and diabetes status. Results We analyzed 1102 procedures: 624 isolated AVRs and 478 AVRs with coronary artery bypass graft (CABG). For isolated AVR, there was no significant difference in 30-d mortality (p = 0.13) or in major adverse events (p = 0.38) between the groups. In the AVR+CABG group, there was no significant difference in 30-day mortality (p = 0.10) or in the rates of major adverse events (p = 0.37) between the groups. Secondary outcomes (hospital and intensive care unit lengths of stay, valve size and type) did not differ significantly between the groups for isolated AVR or AVR+CABG. Conclusion Despite a higher-risk patient population and changes in the cardiac surgery training model, it appears that outcomes are not negatively affected when a senior trainee acts as the primary surgeon in cases of AVR.

Chen, Kuan-chin Jean; Adams, Corey; Stitt, Larry W.; Guo, L. Ray

2013-01-01

40

Addressing Cultural Variables in Parent Training Programs with Latino Families  

ERIC Educational Resources Information Center

There has recently been increased attention given to understanding how cultural variables may have an impact on the efficacy of treatments with Latino families seeking psychological services. Within parent training programs, understanding the extent to which culture can affect parenting practices is vital to providing quality care. The focus of…

Barker, Chikira H.; Cook, Katrina L.; Borrego, Joaquin, Jr.

2010-01-01

41

Depression, heart rate variability, and exercise training in dialysis patients  

Microsoft Academic Search

Background Functional limitations, altered cardiac autonomic activity, and psychological distress are known disorders in chronic hemodialysis (HD) patients, relating to increased morbidity and mortality. The aim of this study was to examine the influence of an exercise training program on emotional parameters and heart rate variability (HRV) indices, as well as to determine whether emotional stress contributes to autonomic dysfunction

Evangelia Kouidi; Vassilis Karagiannis; Dimitrios Grekas; Apostolos Iakovides; George Kaprinis; Achilleas Tourkantonis; Asterios Deligiannis

2010-01-01

42

Effects of training period on haemorheological variables in regularly trained footballers  

PubMed Central

Objective: To investigate the effects of one football training period on haemorheological variables in regularly trained footballers. Method: Ten subjects were randomly selected from the reserve team of a football club in the Turkish Premier League. During the last week of the football season, one day before a standard training session and two days after the previous league match, venous blood samples were taken (pre-exercise). After 90 minutes of standard training, further blood samples were taken (post-exercise). Blood lactate, blood viscosity, plasma fibrinogen, blood clotting time, acid-base variables, and plasma Na+, K+, and Ca2+ were determined. Results: Haemoglobin, packed cell volume, and mean corpuscular volume were all significantly decreased, whereas white blood cells and platelets were both increased after training. Blood viscosity decreased but the reduction was not significant. Blood lactate, plasma glucose, and Na+ content were significantly increased, but standard bicarbonate, actual bicarbonate, and Ca2+ were significantly decreased. Blood clotting time had shortened significantly after training. Blood viscosity was inversely correlated with plasma glucose concentration (r = –0.48 and p = 0.032). Conclusions: The results show that blood viscosity tends to decrease as the result of this type of training. This is due to a reduction in packed cell volume and mean corpuscular volume. The increased blood lactate does not have an adverse effect on the blood viscosity of these subjects because protective mechanisms develop with regular training throughout the season.

Karakoc, Y; Duzova, H; Polat, A; Emre, M; Arabaci, I

2005-01-01

43

A physics-based approach to the control of homogeneous charge compression ignition engines with variable valve actuation  

Microsoft Academic Search

Homogeneous charge compression ignition (HCCI) is a promising low-temperature combustion strategy for reducing NOx emissions and increasing efficiency in internal combustion engines. However, HCCI has no direct combustion initiator and, when achieved by reinducting or trapping residual exhaust gas with a variable valve actuation (VVA) system, becomes a dynamic process as the temperature of the residual gas couples one cycle

G M Shaver; M J Roelle; P A Caton; N B Kaahaaina; N Ravi; J-P Hathout; J Ahmed; A Kojic; C F Edwards; J C Gerdes

2005-01-01

44

Fault diagnosis for diesel valve trains based on non-negative matrix factorization and neural network ensemble  

NASA Astrophysics Data System (ADS)

It is well known that the vibration signals are unstable when there is some failure in machinery. So in this paper, the cone-shaped kernel distributions (CKD) of vibration acceleration signals acquired from the cylinder head in eight different states of valve train were calculated and displayed in grey images. Meanwhile, non-negative matrix factorization (NMF) was used to decompose multivariate data, and neural network ensemble (NNE), which is of better generalization capability for classification than a single neural network, was used to perform intelligent diagnosis without further fault feature (such as eigenvalues or symptom parameters) extraction from time-frequency distributions. It is shown by the experimental results that the faults of diesel valve trains can be accurately classified by the proposed method.

Qinghua, Wang; Youyun, Zhang; Lei, Cai; Yongsheng, Zhu

2009-07-01

45

THE INFLUENCE OF VARIABLE VALVE ACTUATION ON THE PART LOAD FUEL ECONOMY OF A MODERN LIGHT-DUTY DIESEL ENGINE  

Microsoft Academic Search

An investigation has been carried out to identify how variable valve actuation (VVA) can be used to improve the part load fuel economy of a modern light-duty diesel engine. The base engine examined employed a variable geometry turbo-charger (VGT) with air to air inter- cooling, cooled exhaust gas re-circulation (EGR) and common rail fuel injection. The VVA system investigated was

Tim Lancefield

46

Heart rate variability in children with aortic valve stenosis - a pilot study  

PubMed Central

Introduction The aim of our prospective study was to evaluate heart rate variability (HRV) in children with aortic valve stenosis (AS) and its relationship with left ventricular mass and peak transaortic valve pressure gradient (PG). Material and methods Sixty children with AS divided into 3 groups according to their PG and 60 healthy controls were studied. Holter ECG monitoring with time domain HRV analysis was performed. Left ventricular mass was calculated by echocardiography. Results Mean values of all HRV parameters were statistically significantly lower (p < 0.001) in children with AS than in controls (respectively: SDNN 127.8 ±28.2 ms; 162.6 ±38.0 ms, SDNN day 99.7 ±26.6 ms; 134.1 ±36.1 ms, SDNN night 99.9 ±32.8 ms; 123.4 ±45.7 ms, SDANN 112.2 ±27.7 ms; 142.4 ±34.6, SDNNi 62.2 ±16.2 ms; 75.9 ±21.6, RMSSD 39.6 ±12.1 ms; 50.3 ±16.7 ms, rMSSD day 33.6 ±10.9 ms; 43.1 ±14.7 ms, rMSSD night 49.8 ±18.1 ms; 64.4 ±24.9 ms, pNN50 16.4 ±9.5%; 23.5 ±11.7%, pNN50 day 12.0 ±8.5%; 18.4 ±10.7%, pNN50 night; 26.5 ±14.8%; 36.4 ±17.4%. No significant differences between the mean values of HRV parameters in children with different PG and with and without myocardial hypertrophy were found. In children with AS and ventricular arrhythmia SDNN day was significantly lower (p < 0.05) compared to patients without arrhythmia (94.9 ±22.1 ms vs. 109.3 ±22.5 ms). Conclusions In children with AS the balance of the autonomic nervous systemic disturbed which manifests in an increase in sympathetic and decrease in parasympathetic activity. Transaortic valve pressure gradient and myocardial hypertrophy do not influence the HRV. The SDNN reduction during the day period may indicate the risk of ventricular arrhythmia in children with AS.

Piorecka-Makula, Anna; Bobkowski, Waldemar

2013-01-01

47

Multirate closed-loop system identification of a variable valve timing actuator for an internal combustion engine  

Microsoft Academic Search

This paper applies the multi-rate closed-loop system identification (ID) technique to a continuously variable valve timing (VVT) actuator system. Limited by the sample rate of the crank-based cam position sensor, function of engine speed, the actuator control sample rate is different from that of cam position sensor. Multi-rate system identification is a necessity for this application. On the other hand,

Zhen Ren; Guoming G. Zhu

2010-01-01

48

Clinically Relevant Discovery Recognized During Simulator Training Session: Free-Standing PEEP Valve Solves Problem of Incompetent Exhalation Unidirectional Valve in an Anesthesia Circle Breathing System  

Microsoft Academic Search

While conducting a case-based teaching session using a full-scale simulator, the authors discovered that placement of a unidirectional PEEP valve in the expiratory limb corrects the gas flow pattern, despite an exhalation valve failure.

Tammy Y. Euliano; Michael E. Mahla; Michael J. Banner

1998-01-01

49

The Impact of Training and Other Variables on the Preparation of the Public Welfare Workforce  

Microsoft Academic Search

The purpose of this research was to examine the impact of innovative training for public welfare workers on training outcomes, as well as the individual and organizational mediators of these outcomes. This study surveyed 623 public welfare workers on training satisfaction, knowledge, transfer, individual variables such as personality and learning readiness, and organizational variables such as team and supervisor support

Dana J. Sullivan; Becky F. Antle; Anita P. Barbee; Rich Egbert

2009-01-01

50

Testing the Impact of Job-Related Variables on a Utility Judgment Training Criterion beyond Background and Affective Reaction Variables  

ERIC Educational Resources Information Center

We tested the incremental impact of a job-related set of variables for explaining a utility judgment training effectiveness variable, that is, course completion skill preparedness, beyond background and course-related variables. Our respondents were two different emergency medical service samples, 415 basics and 742 paramedics, from the 2008 US…

Blau, Gary; Gibson, Greg; Bentley, Melissa; Chapman, Susan

2012-01-01

51

Un-throttling a direct injection gasoline homogeneous mixture engine with variable valve actuation  

Microsoft Academic Search

Two direct injection spark ignition (DISI) engines with identical combustion chamber geometries and fuel injection systems were used to investigate fuel economy, exhaust emissions, the in-cylinder flow field, the fuel spray behaviour and combustion characteristics with early inlet valve closure (EIVC) strategies aimed at reducing parasitic induction work owing to throttling. One engine had extensive optical access through a transparent

R Patel; N Ladommatos; P A Stansfield; G Wigley; C P Garner; G Pitcher; J W G Turner; H Nuglisch; J Helie

2010-01-01

52

Resistance Training Increases the Variability of Strength Test Scores.  

National Technical Information Service (NTIS)

Informal observations made while conducting a meta-analysis of resistance training programs suggested that the between-person variation in strength test scores is greater after training than before. This study treated the informal observation as a hypothe...

A. C. Barnard J. R. Vickers L. K. Hervig

2009-01-01

53

Changes of Serum ?-Endorphin by Programmed Exercise Training Are Correlated with Improvement of Clinical Symptoms and Quality of Life in Female Mitral Valve Prolapse Syndrome  

Microsoft Academic Search

Background: Mitral valve prolapse (MVP) is a common entity in female population. Although this is a minor disease, it may cause annoying symptoms that impair quality of life (QOL), and no established therapy for this problem. The aim of this study isto examine whether programmed exercise training by treadmill in female MVP syndrome would improve clinical symptoms and QOL. Methods:

Huei-Fong Hung; Pai-Feng Kao; Yu-Shuang Lin; Feng-Chia Chen; Fu-Chean Chen; Jen-Chen Tsai; Paul Chan

2007-01-01

54

A new electromagnetic valve actuator  

Microsoft Academic Search

In conventional internal combustion (IC) engines, en- gine valve displacements are fixed relative to crankshaft position. If these valves are actuated as a variable function of crankshaft an- gle, significant improvements in fuel economy can be achieved. Ex- isting electromagnetically actuated variable-valve-timing (VVT) systems characteristically use springs to provide the large iner- tial power to move the engine valves. However,

W. S. Changt; T. A. Parlikart; M. D. Seemant; D. J. Perreaultt; J. G. Kassakian; T. A. Keirnl

2002-01-01

55

Hydraulic damper for vehicles with variable orifice piston valving for varying damping force  

SciTech Connect

A hydraulic damping unit is described for controlling the spring action of vehicle suspension springs comprising a cylinder tube having a hydraulic fluid therein, a valved piston having a generally cylindrical body mounted for linear stroking movement in the cylinder tube and hydraulically separating the cylinder tube into first and second chambers, valve means within the body of the piston for controlling the flow of hydraulic fluid between the chambers through the piston, a piston rod connected directly to the body of the piston and extending to the exterior of the damping unit, a rotatable actuator operatively mounted in the piston rod. The valve means consists of an orifice plate fixed within the body of the piston having a plurality of hydraulic fluid flow controlling orifices therethrough, first and second deflectable spring disk means mounted on opposite sides of the orifice plate operatively associated with the orifices providing primary control of the damping force of the unit, fastener means extending through the orifice plate and the first and second disk means within the body of the piston, separate and varying size fluid flow passages extended through the fastener means in parallel with the orifices. The fastener means a head portion within the body of the piston, a selector plate rotatably mounted on the head portion and having a selector opening therein selectively registrable with any of the passages, means operatively connecting the selector plate to the actuator for rotation thereby so that any of the fluid flow passages can be selected for varying the damping action of the unit.

Fannin, W.V.; Buchanan, H.C. Jr.

1987-08-11

56

Stressful Underwater Demolition Training. Serum Urate and Cholesterol Variability.  

National Technical Information Service (NTIS)

Individuals with ultimately middle to low normal-range levels of serum uric acid and cholesterol demonstrated highly significant rises in these serum fractions during specific stages of a four-month underwater demolition training period. Serum urate conce...

R. H. Rahe R. J. Arthur

1967-01-01

57

Linear dynamic segmental HMMs: variability representation and training procedure  

Microsoft Academic Search

This paper describes investigations into the use of linear dynamic segmental hidden Markov models (SHMMs) for modelling speech feature-vector trajectories and their associated variability. These models use linear trajectories to describe how features change over time, and distinguish between extra-segmental variability of different trajectories and intra-segmental variability of individual observations around any one trajectory. Analyses of mel cepstrum features have

Wendy J. Holmes; Martin J. Russell

1997-01-01

58

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

59

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

60

Perceptions of Training-Related Factors and Personal Variables as Predictors of Transfer Implementation Intentions  

Microsoft Academic Search

A number of factors influence the outcomes of computer skills training and the likelihood of successful transfer. The first empirical test of a conceptual model of training transfer sought to explain how trainees' perceptions of various in-training transfer-enhancing activities such as overlearning, fidelity, stimulus variability, principles-meaningfulness, self-management activities, relapse prevention, and goal setting would predict the self-efficacy and implementation intentions

M. Anthony Machin; Gerard J. Fogarty

2003-01-01

61

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

62

Visuospatial Ability Factors and Performance Variables in Laparoscopic Simulator Training  

ERIC Educational Resources Information Center

|Visuospatial ability has been shown to be important to several aspects of laparoscopic performance, including simulator training. Only a limited subset of visuospatial ability factors however has been investigated in such studies. Tests for different visuospatial ability factors differ in stimulus complexity, in their emphasis on identifying…

Luursema, Jan-Maarten; Verwey, Willem B.; Burie, Remke

2012-01-01

63

Visuospatial Ability Factors and Performance Variables in Laparoscopic Simulator Training  

ERIC Educational Resources Information Center

Visuospatial ability has been shown to be important to several aspects of laparoscopic performance, including simulator training. Only a limited subset of visuospatial ability factors however has been investigated in such studies. Tests for different visuospatial ability factors differ in stimulus complexity, in their emphasis on identifying…

Luursema, Jan-Maarten; Verwey, Willem B.; Burie, Remke

2012-01-01

64

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

65

Aortic valve replacement: is porcine or bovine valve better?  

PubMed

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: 'Is porcine or bovine valve better for aortic valve replacement?' Altogether, 562 papers were found using the reported search, of which 15 represented the best evidence to answer the question. All papers represent either level 1 or 2 evidence. The authors, journal, date, country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. This best evidence paper includes 9880 patients from 1974-2006 to compare both valve types. All studies compared either all or some of the following outcomes: complication, durability, mortality, functional status and haemodynamic function. Ten of 15 papers assessed the complication profile due to aortic valve replacement in both valve types. Four papers concluded that bovine valves are superior, whereas only one favoured porcine valves. Five papers showed a similar complication profile between both valves. Six of 15 papers commented on valve durability. Both porcine and bovine valve groups have two papers each to support their superiority in valve durability. Two papers demonstrated similar durability in both valves. There are 11 papers comparing the postoperative mortality. We suggest that there is no difference in mortality profile as eight papers showed that both valves had similar mortality profiles. Two papers supported bovine valve and one paper supported porcine valve in this aspect. There were four papers assessing the postoperative functional status, with three papers suggesting that both valve types had similar clinical improvement postoperatively. Eleven papers compared the haemodynamic function. Nine papers were in favour of bovine valves. Two papers demonstrated similar haemodynamic profiles in both valves. In conclusion, the bovine valve is superior in its complication and haemodynamic profiles. Both bovine and porcine valves have comparable results with regard to the mortality, postoperative functional status and valve durability. Significant variability between the valve manufacturers, study designs, study period and patient population in the above studies impose limitations to the comparison of both valves. PMID:23211215

Yap, Kok Hooi; Murphy, Ralph; Devbhandari, Mohan; Venkateswaran, Rajamiyer

2012-12-04

66

Percutaneous balloon dilatation of the mitral valve: an analysis of echocardiographic variables related to outcome and the mechanism of dilatation  

Microsoft Academic Search

Twenty two patients (four men, 18 women, mean age 56 years, range 21 to 88 years) with a history of rheumatic mitral stenosis were studied by cross sectional echocardiography before and after balloon dilatation of the mitral valve. The appearance of the mitral valve on the pre-dilatation echocardiogram was scored for leaflet mobility, leaflet thickening, subvalvar thickening, and calcification. Mitral

G T Wilkins; A E Weyman; V M Abascal; P C Block; I F Palacios

1988-01-01

67

Training and recovery behaviors of exchange bias in FeNi/Cu/Co/FeMn spin valves at high field sweep rates  

NASA Astrophysics Data System (ADS)

Training and recovery of exchange bias in FeNi/Cu/Co/FeMn spin valves have been studied by magnetoresistance curves with field sweep rates from 1000 to 4800 Oe/s. It is found that training and recovery of exchange field are proportional to the logarithm of the training cycles and recovery time, respectively. These behaviors are explained within the model based on thermal activation. For the field sweep rates of 1000, 2000 and 4000 Oe/s, the relaxation time of antiferromagnet spins are 61.4, 27.6, and 11.5 in the unit of ms, respectively, much shorter than the long relaxation time (˜102s) in conventional magnetometry measurements.

Yang, D. Z.; Kapelrud, A.; Saxegaard, M.; Wahlström, E.

2012-09-01

68

Effect of altitude training on haematological variables in women volleyball players  

Microsoft Academic Search

BackgroundAthletes from many endurance disciplines include altitude training in their yearly training programme. In volleyball, it is necessary to clarify the haematological benefits and improvement in sports performance.ObjectiveTo investigate the influence of moderate altitude on haematological variables in a women's volleyball team (Honor Division – Spain).Design and settingWe assessed 14 elite female volleyball players for two weeks in normoxia (640

B Cueto-Martín; J C de la Cruz-Márquez; J C de la Cruz-Campos; A de la Cruz-Campos

2011-01-01

69

Physics-based closed-loop control of phasing, peak pressure and work output in HCCI engines utilizing variable valve actuation  

Microsoft Academic Search

Homogeneous charge compression ignition (HCCI) represents a promising combustion strategy for future engines. However, HCCI lacks an easily identified combustion trigger and, when achieved via variable valve actuation (VVA), includes cycle-to-cycle coupling through the exhaust gas. This makes controlling the process decidedly non-trivial. To address these issues, the development of a closed-loop controller for HCCI combustion phasing and peak pressure

Gregory M. Shaver; J. Christian Gerdes; Matthew Roelle

2004-01-01

70

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.

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

2013-01-01

71

Output Feedback Preview Control of an Electromechanical Valve Actuator  

Microsoft Academic Search

In an electromechanical valve actuated engine, solenoid actuators drive the valves that control airflow into the cylinders, allowing elimination of the camshaft and flexible control of the valve timing. Individual control of the valves provides flexibility in valve timing over all engine operating conditions and fully enables the benefits of variable valve timing. This paper describes a closed-loop preview control

Lawrence Mianzo; Huei Peng

2007-01-01

72

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

2012-06-02

73

Variable structure systems theory based training strategies for computationally intelligent systems  

Microsoft Academic Search

Variable structure systems (VSS) theory, which is particularly well developed for tracking control of uncertain nonlinear systems, has inspired scientists in developing solutions to ill-posed problems like the design of training criteria under a set of conditions and performance metrics. The underlying idea has been to exploit the invariance properties introduced by the theory together with the parametric flexibility of

Mehmet Önder Efe; Okyay Kaynak

2001-01-01

74

DATA-BASED DECISION MAKING: THE IMPACT OF DATA VARIABILITY, TRAINING, AND CONTEXT  

PubMed Central

The current study examines agreement among individuals with varying expertise in behavior analysis about the length of baseline when data were presented point by point. Participants were asked to respond to baseline data and to indicate when to terminate the baseline phase. When only minimal information was provided about the data set, experts and Board Certified Behavior Analyst participants generated baselines of similar lengths, whereas novices did not. Agreement was similar across participants when variability was low but deteriorated as variability in the data set increased. Participants generated shorter baselines when provided with information regarding the independent or dependent variable. Implications for training and the use of visual inspection are discussed.

Vanselow, Nicholas R; Thompson, Rachel; Karsina, Allen

2011-01-01

75

Fuel economy effects and incremental cost, weight and lead time impacts of employing Variable Valve Timing (VVT) engine technology. Final report  

SciTech Connect

In recent years, new mechanical inventions and electronic engine controls have made variable valve timing a production possibility. A few manufacturers have VVT systems in production. The report presents a paper study of the fuel economy benefits and the incremental manufacturing costs, tooling costs and engine weights as well as production leadtime for a VVT engine. Emission levels are considered. As a base, a 4-valve, V-6 engine of 3.5 liters was used with a 3750 lb. passenger vehicle. The VVT system applied to that engine was a combination of the Atsugi cam phasing system, a modified Mitsubishi MIVEC long and short duration cam system and intake port throttle. The final VVT engine was presumed to have reduced idle speed (500 vs 640 rpm base) and an 8% lower displacement (3.22 liters).

Patterson, D.; Simko, A.; Reilly, D.

1997-05-19

76

Variable Valve Actuation  

Microsoft Academic Search

Many approaches exist to enable advanced mode, low temperature combustion systems for diesel engines - such as premixed charge compression ignition (PCCI), Homogeneous Charge Compression Ignition (HCCI) or other HCCI-like combustion modes. The fuel properties and the quantity, distribution and temperature profile of air, fuel and residual fraction in the cylinder can have a marked effect on the heat release

Jeffrey Gutterman; A. J. Lasley

2008-01-01

77

Heart rate variability reflects training load and psychophysiological status in young elite gymnasts.  

PubMed

Sartor, F, Vailati, E, Valsecchi, V, Vailati, F, La Torre, A. Heart rate variability reflects training load and psychophysiological status in young elite gymnasts. J Strength Cond Res 27(10): 2782-2790, 2013-In gymnastics, monitoring of the training load and assessment of the psychophysiological status of elite athletes is important for training planning and to avoid overtraining, consequently reducing the risk of injures. The aim of this study was to examine whether heart rate variability (HRV) is a valuable tool to determine training load and psychophysiological status in young elite gymnasts. Six young male elite gymnasts took part in a 10-week observational study. During this period, beat-to-beat heart rate intervals were measured every training day in weeks 1, 3, 5, 7, and 9. Balance, agility, upper limb maximal strength, lower limb explosive, and elastic power were monitored during weeks 2, 4, 6, 8, and 10. Training load of each training session of all 10 weeks was assessed by session rating of perceived exertion (RPE) and psychophysiological status by Foster's index. Morning supine HRV (HF% and LF%/HF%) correlated with the training load of the previous day (r = 0.232, r = -0.279, p < 0.05 ). Morning supine to sitting HRV difference (mean R wave to R wave interval (RR), mean heart rate, HF%, SD1) correlated with session RPE of the previous day (r = -0.320, r = 0.301, p < 0.01; r = 0.265, r = -0.270, p < 0.05) but not with Foster's index. Training day/reference day HRV difference (mean RR, SD1) showed the best correlations with session RPE of the previous day (r = -0.384, r = -0.332, p < 0.01) and Foster's index (r = -0.227, r = -0.260, p < 0.05). In conclusion, HRV, and in particular training day/reference day mean RR difference or SD1 difference, could be useful in monitoring training load and psychophysiological status in young male elite gymnasts. PMID:23364293

Sartor, Francesco; Vailati, Emanuele; Valsecchi, Viola; Vailati, Fulvio; La Torre, Antonio

2013-10-01

78

Heart rate variability in prediction of individual adaptation to endurance training in recreational endurance runners.  

PubMed

The aim of this study was to investigate whether nocturnal heart rate variability (HRV) can be used to predict changes in endurance performance during 28 weeks of endurance training. The training was divided into 14 weeks of basic training (BTP) and 14 weeks of intensive training periods (ITP). Endurance performance characteristics, nocturnal HRV, and serum hormone concentrations were measured before and after both training periods in 28 recreational endurance runners. During the study peak treadmill running speed (Vpeak ) improved by 7.5 ± 4.5%. No changes were observed in HRV indices after BTP, but after ITP, these indices increased significantly (HFP: 1.9%, P=0.026; TP: 1.7%, P=0.007). Significant correlations were observed between the change of Vpeak and HRV indices (TP: r=0.75, P<0.001; HFP: r=0.71, P<0.001; LFP: r=0.69, P=0.01) at baseline during ITP. In order to lead to significant changes in HRV among recreational endurance runners, it seems that moderate- and high-intensity training are needed. This study showed that recreational endurance runners with a high HRV at baseline improved their endurance running performance after ITP more than runners with low baseline HRV. PMID:21812828

Vesterinen, V; Häkkinen, K; Hynynen, E; Mikkola, J; Hokka, L; Nummela, A

2011-08-03

79

Heart rate variability in myocardial infarction patients: Effects of exercise training.  

PubMed

Heart rate variability (HRV) is a simple and noninvasive measure that estimates cardiac autonomic modulation, mainly the parasympathetic contribution. Increased sympathetic and/or decreased parasympathetic nervous activity is seen in post-myocardial infarction (MI) patients. Consequently, these patients present reduced HRV, which has been associated with increased risk of adverse events and mortality. Exercise training, recommended as a complementary therapy for patients with cardiovascular disease, has shown numerous beneficial effects. The main aim of the present manuscript was to provide a critical review of studies investigating the effects of exercise training on cardiac autonomic modulation, through HRV, in MI patients and the possible mechanisms involved. Despite conflicting evidence, exercise training appears to be a useful therapeutic intervention to improve the unbalanced autonomic function of MI patients. Finally, the mechanisms involved are not yet well understood, but nitric oxide bioavailability and angiotensin II levels seem to play an important role. PMID:23993292

Oliveira, Nórton Luís; Ribeiro, Fernando; Alves, Alberto Jorge; Teixeira, Madalena; Miranda, Fátima; Oliveira, José

2013-08-30

80

Orthostatic influence on heart rate and blood pressure variability in trained persons with tetraplegia  

Microsoft Academic Search

To examine the orthostatic influence on heart rate and blood pressure variability in persons with tetraplegia playing wheelchair\\u000a basketball, ten trained persons with tetraplegia, ten untrained persons with tetraplegia, and ten able-bodied participated\\u000a in this study. Spectrum analysis of the ECG R–R interval and blood-pressure on a beat-by-beat basis during head-up tilt 60°\\u000a sitting were performed. The ratio of the

Yasuko Otsuka; Norihiro Shima; Toshio Moritani; Kuniharu Okuda; Kyonosuke Yabe

2008-01-01

81

Increased heart rate variability and executive performance after aerobic training in the elderly  

Microsoft Academic Search

This study examined the effects of two short physical training programs on various parameters of heart rate variability (HRV)\\u000a and on executive performance in older people. Twenty-four sedentary men and women aged 65–78 years were randomly assigned\\u000a to an aerobic exercise program or a stretching program three times a week for 12 weeks. Resting HRV was measured in time and\\u000a frequency domains

Cédric T. Albinet; Geoffroy Boucard; Cédric A. Bouquet; Michel Audiffren

2010-01-01

82

Influence of gender and types of sports training on QT variables in young elite athletes  

Microsoft Academic Search

Influence of gender and sports training on QT variables such as QT interval and dispersion (QT dispersion: QTD) in young elite athletes were evaluated. Subjects included 104 male and 97 female Japanese elite athletes (mean age 21.6 years). Sports included basketball, fencing, gymnastics, judo, swimming, tennis, track and field and volleyball. Age-matched healthy non-athletes (32 men and 20 women) were

Kazuto Omiya; Hiromitsu Sekizuka; Keisuke Kida; Kengo Suzuki; Yoshihiro J. Akashi; Haruo Ohba; Haruki Musha

2012-01-01

83

The effects of variable speed and drive train component efficiencies on wind turbine energy capture  

SciTech Connect

A wind turbine rotor achieves optimal aerodynamic efficiency at a single tip-speed ratio (TSR). To maintain that optimal TSR and maximize energy capture in the stochastic wind environment, it is necessary to employ variable-speed operation. Conventional constant-speed wind turbines have, in the past, been converted into variable-speed turbines by attaching power electronics to the conventional induction generator and gearbox drive train. Such turbines have shown marginal, if any, improvement in energy capture over their constant-speed counterparts. These discrepancies have been shown to be the result of drive train components that are not optimized for variable-speed operation. Traditional drive trains and power electronic converters are designed to achieve maximum efficiency at full load and speed. However, the main energy producing winds operate the turbine at light load for long periods of time. Because of this, significant losses to efficiency occur. This investigation employs a quasi-static model to demonstrate the dramatic effect that component efficiency curves can have on overall annual energy capture.

Fingersh, L.J.; Robinson, M.C.

1998-05-01

84

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

85

Sensorless control of a rotary valve actuator for combustion engines  

Microsoft Academic Search

A robust sensorless control system to use in an electromotive valve actuator for combustion engines is described. The mechanical setup of a rotary valve actuator, which transfers the angular force by a bell crank to the valves, combines the advantage of variable mechanical and electromechanical valve drives because of adjustable stroke and opening time. The option to control several valves

S. Braune; K.-D. Kramer

2008-01-01

86

Independent factors associated with longevity of prosthetic pulmonary valves and valved conduits  

Microsoft Academic Search

Objective: To evaluate the age dependence of variables predictive of pulmonary valve prosthesis replacement, we conducted the following analysis. Methods: Retrospective analysis of 945 operations in 726 patients undergoing placement of pulmonary valve prostheses was performed. Age was identified as a strong independent predictor of valve failure. The database was stratified into age-based subsets and predictors of valve replacement were

Christopher A Caldarone; Brian W McCrindle; Glen S Van Arsdell; John G Coles; Gary Webb; Robert M Freedom; William G Williams

2000-01-01

87

Diverter valve  

Microsoft Academic Search

Diverter valve is disclosed for preventing blow-outs in oil wells during the early stages of drilling. The diverter valve has a simplified construction which reduces maintenance problems during use in the field.

Seabourn

1983-01-01

88

Rotary valve  

SciTech Connect

This patent describes a method of controlling the passage of material through a structure of the type which includes valve body means defining a valve chamber and having an inlet port and an outlet port each communicating between the valve chamber and the exterior of the valve body means; annular inlet seal means in the valve chamber and having an inlet passage therethrough communicating in seal engagement with the inlet port; annular outlet seal means in the valve chamber and having an outlet passage therethrough communicating in sealing engagement with the outlet port; valve member means for controlling the passage of material through the valve body means. The valve member means having a frustoconically shaped outer surface and being disposed within the valve chamber with the frustoconically shaped outer surface in close slidable sealing engagement with the annular outlet seal means and being adapted to rotate about its longitudinal axis within the valve chamber; the method comprising the steps of: (a) introducing fluid generally transversely into the inlet port at a point upstream of the annular inlet seal means; (b) supplying material to the inlet port upstream of the point of introduction of the fluid; and (c) rotating the valve member means relative to the valve body means to block flow of the material and the introduced fluid through the valve body means from the inlet port, and, alternately, to permit flow of the material and the introduced fluid into the valve body means via the inlet port and out of the valve body means via the outlet port.

Rohlfing, R.G.; Norwood, D.D.

1988-09-27

89

Valve apparatus  

SciTech Connect

A description is given of a valve apparatus for use in subterranean well and carriable on a fluid transmission conduit insertable therein, comprising: ball valve head means having camway slot means defined exteriorly theron; valve seat means having camway ball means secured thereto and carriable in said camway slot means to pivot said valve head means on said seat means to shift said appartus between open and closed positions in response to manipulation of said fluid transmission conduit.

McStravick, D.; Roberts, W.

1980-07-01

90

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

91

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

92

Valves Module  

NSDL National Science Digital Library

The Center for the Advancement of Process Technology presents this free sample module on valves in the process industries. The interactive resource includes 55 screens and will help learners with both the details of valve systems and the process technician's role in valve operation and maintenance.

2013-01-07

93

Design of training schedules for medical-image readers: the effects of variability and difficulty levels of the training stimuli  

Microsoft Academic Search

We report two studies on the design of training schedules for medical-image readers. Experiment 1 required subjects to learn to classify ultrasound images of six different phantoms; one group of subjects trained on images that varied on just two of the four possible dimensions of variation on each day, while the other group trained on images that varied on all

Ian R. Davies; Penny Roling; Paul T. Sowden; Sean M. Hammond; Robert C. Chivers

1996-01-01

94

Highly variable spike trains underlie reproducible sensorimotor responses in the medicinal leech.  

PubMed

The nervous system of the leech is a particularly suitable model to investigate neural coding of sensorimotor responses because it allows both observation of behavior and the simultaneous measurement of a large fraction of its underlying neuronal activity. In this study, we used a combination of multielectrode recordings, videomicroscopy, and computation of the optical flow to investigate the reproducibility of the motor response caused by local mechanical stimulation of the leech skin. We analyzed variability at different levels of processing: mechanosensory neurons, motoneurons, muscle activation, and behavior. Spike trains in mechanosensory neurons were very reproducible, unlike those in motoneurons. The motor response, however, was reproducible because of two distinct biophysical mechanisms. First, leech muscles contract slowly and therefore are poorly sensitive to the jitter of motoneuron spikes. Second, the motor response results from the coactivation of a population of motoneurons firing in a statistically independent way, which reduces the variability of the population firing. These data show that reproducible spike trains are not required to sustain reproducible behaviors and illustrate how the nervous system can cope with unreliable components to produce reliable action. PMID:12486172

Zoccolan, Davide; Pinato, Giulietta; Torre, Vincent

2002-12-15

95

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

96

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

97

Poppet valve  

SciTech Connect

A float device for use in a well bore cementing operation, is described comprising: a casing equipment housing including a tubular section having an axial bore therethrough; a valve assembly axially disposed in the tubular section axial bore of the casing equipment housing, the valve assembly including: a unitary tubular valve body having a radially extending flange at the top exterior thereof defining a plug seat; a guide spider above the valve seat comprising radially oriented legs extending inwardly from the wall of the axial bore of the unitary tubular valve body to a central cylindrical collar having an axial stem bolt bore therethrough and a shoulder having, in turn, an upset extending upwardly therefrom; a valve poppet having an upwardly-facing valve surface of frustoconical configuration thereon disposed adjacent the valve seat sealingly engaging the generally frustoconical configuration thereof and having an elastomeric sheath over the frustoconical configuration of the upwardly-facing valve surface, the elastomeric sheath including a circumferentially-extending lip at the lower periphery thereof; a stem bolt secured to the valve poppet and extending upwardly through the stem bolt bore in the collar; a spring retention cap at the top of the stem bolt, and; a coil spring disposed about the stem bolt above the collar; and a cement sheath surrounding the valve assembly and substantially filling the annular void between the valve assembly and the wall of the tubular section bore of the casing equipment housing, the cement sheath having a top surface substantially flush with the plug seat on the valve body.

Stepp, L.W.; Giroux, R.L.

1987-12-15

98

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

99

Valve lock  

NASA Astrophysics Data System (ADS)

A valve security lock is provided which secures a double union ball valve. The lock is formed from a band inserted through slits in a tube, with that combination being positioned over the valve stem to be secured, and the ends of the band wrapped around the circumference of the double union ball valve. The apparatus is secured around the double union ball valve by insertion of the shank of a lock of known kind through holes in the ends of the band. In a fluid control system, the valve security lock provides a highly visible means to prevent accidental turn-ons or turn-offs during system maintenance, but which can be easily disengaged by persons having the key or combination to the shank type lock.

Burley, Richard K.; Guirguis, Kamal S.

1992-11-01

100

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

2011-11-29

101

Integrated control and power electronics for an electro-mechanical valve actuation system  

Microsoft Academic Search

In an electro-mechanical valve actuated engine, computer-controlled solenoid actuators drive the valves that control airflow into the cylinders, allowing elimination of the camshaft and enabling fully variable valve timing. Control of individual valve timing optimized over all engine operating conditions allows the benefits of variable valve timing to be realized. This paper presents a power electronics and control electronics architecture

Lawrence A. Mianzo; Stephen J. Newton; Zeljko Popovic

2005-01-01

102

Effect of exercise intensity and repetition on heart rate variability during training in elite trotting horse.  

PubMed

RR intervals of ten elite trotting horses were recorded during an interval training session performed on track. This study examined two hypotheses. Firstly, like in humans, the hyperpnea combined with a decrease in cardiac autonomic control on heart rate during heavy exercise could result in a prevalence of high frequency heart rate variability. Secondly, this prevalence could increase with the heavy exercise repetition. Two exercise intensities were compared: moderate (ME) and heavy (HE). Furthermore, heavy exercise repetitions were compared between the beginning and the end of the interval training session. When comparing ME and HE periods: heart rate was significantly lower (155 +/- 12 vs. 210 +/- 9 ms, p < 0.001), LF spectral energy (0.04 - 0.2 Hz) was significantly higher (ME: 6.94 +/- 4.80 and HE: 0.24 +/- 0.14 ms(2) . Hz (-1), p < 0.001) whereas HF (0.2 - 2 Hz) was significantly lower (ME: 7.09 +/- 2.24 and HE: 10.60 +/- 3.64 ms(2) . Hz (-1), p < 0.05). In relative terms, ME showed similar results in both LFn (LF/LF+HF) and HFn (HF/LF+HF) whereas HE showed a large prevalence of HFn energy compared to LFn (p < 0.001). The difference in LF/HF ratio between the two exercise conditions was significant (1.14 +/- 0.92 vs. 0.09 +/- 0.12, p < 0.001). Exercise repetition induced a significant increase in heart rate between the beginning and the end of the interval training session (207 +/- 10 beats . min (-1) vs. 212 +/- 9 beats . min (-1), p < 0.001) whereas LF energy decreases (1.54 +/- 1.65 vs. 0.32 +/- 0.24 ms(2) . Hz (-1), p < 0.01) and HF energy remained constant (10.79 +/- 4.10 vs. 10.40 +/- 3.35 ms(2) . Hz (-1), NS). This study confirmed the results observed in humans during heavy exercise conditions with a large prevalence of HF in contrast to LF, this prevalence increasing with exercise repetitions. The observed decrease in LF/HF ratio could provide an index of hyperpnea in horses during interval training. PMID:16320171

Cottin, F; Médigue, C; Lopes, P; Petit, E; Papelier, Y; Billat, V L

2005-12-01

103

Fast-Acting Valve.  

National Technical Information Service (NTIS)

A fast-acting valve includes an annular valve seat that defines an annular valve orifice between the edges of the annular valve seat, an annular valve plug sized to cover the valve orifice when the valve is closed, and a valve-plug holder for moving the a...

B. V. Wojciechowski R. J. Pegg

2003-01-01

104

Absent pulmonary valve  

MedlinePLUS

Absent pulmonary valve syndrome; Congenital absence of the pulmonary valve; Pulmonary valve agenesis ... Absent pulmonary valve occurs when the pulmonary valve doesn't form or develop properly while the baby is in ...

105

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

106

The Extended Canter: A Comparison of Some Kinematic Variables in Horses Trained for Dressage and for Racing  

Microsoft Academic Search

This study was designed to test the hypothesis that there is no significant difference in selected temporal and linear stride variables of the extended canter in horses bred and trained for dressage or racing. Nine advanced-level dressage horses and 7 Thoroughbred racehorses were filmed at a frame rate of 200 Hz at an extended canter on a sand track. Two

H. M. Clayton

1993-01-01

107

Heart Rate Variability in Obese Children: Relations to Total Body and Visceral Adiposity, and Changes with Physical Training and Detraining  

Microsoft Academic Search

Objective: Heart rate variability provides non-invasive information about cardiac parasympathetic activity (PSA). We determined in obese children: (1) relations of baseline PSA to body composition and hemodynamics; (2) effects of physical training (PT) and cessation of PT; and (3) which factors explained individual differences in responsivity of PSA to the PT.Research Methods and Procedures: The root mean square of successive

Bernard Gutin; Paule Barbeau; Mark S. Litaker; Michael Ferguson; Scott Owens

2000-01-01

108

Interobserver and interequipment variability of echo-doppler examination of the portal vein: Effect of a cooperative training program  

Microsoft Academic Search

The aim of this study was to assess the interobserver, interequipment, and time-dependent variabilities of echo-Doppler measurements of portal blood flow velocity (PBV), portal vein diameters (PVDs) and their derived parameters, portal blood flow (PBF), and congestion index (CI) in cirrhotic patients. The influence of a cooperative training program of the operators on the reproducibility of the results was also

Carlo Sabbá; Carlo Merkel; Marco Zoli; Giovanna Ferraioli; Stefano Gaiani; David Sacerdoti; Luigi Bolondi

1995-01-01

109

Variable pressure recovery  

SciTech Connect

Control valves have been classified into two broad categories according to the nature of the pressure recovery inside the valve: low recovery valves (typically globe style) and high recovery valves (typically rotary style). This relates to the difference between the lowest absolute pressure at the vena contracta in the valve and the downstream pressure in ratio to the actual pressure drop across the valve. With some new developments in rotary control valves this classification has become insufficient and a new concept variable recovery - needs to be brought into wide usage to be able to evaluate the performance of these designs. In a global style control valve, the pressure recovery is fairly constant throughout the valve opening range. The liquid pressure recovery factor, F/sub L/, can be used as an indicator of how low the pressure recovery in the specific valve is, so that high F/sub L/ factors indicate low recovery and vice versa. Globe valve F/sub L/ range between 0.7 and 0.9 for standard designs depending on the valve style, and stay constant at all valve openings when we use the flow-to-open configuration. Globe valves are typically labeled low recovery. On the other hand, the rotary style valves have, for example, an F/sub L/ factor of 0.55 at full (90/sup 0/) opening for a ball valve and 0.65 at 70/sup 0/ opening for a butterfly valve. These valves typically have been considered high recovery.

Husu, M. (Neles Inc., Glens Falls, NY (US))

1988-09-01

110

Transcatheter valve-in-valve implantation for failing bioprosthetic valves.  

PubMed

Transcatheter valve implantation is becoming an alternative to conventional surgical valve replacement in patients at high surgical risk. While experience and acceptance with transcatheter techniques increased rapidly, transcatheter valve implantation within failing bioprostheses has emerged as a new concept (valve-in-valve implantation). Currently, the majority of prostheses implanted in patients are bioprosthetic valves that are expected to degenerate over time. Valve-in-valve implantation provides great utility in high-operative-risk patients since the mortality risk for reoperation can be significantly higher than for first-time isolated valve replacement. Although two current devices are CE Mark approved in Europe for implantation within native valves, off-label clinical implementation of valve-in-valve have been described in numerous case reports. In this article, we provide an overview of transcatheter valve implantation in failing bioprostheses with an emphasis on the aortic position. PMID:21142638

Azadani, Ali N; Tseng, Elaine E

2010-11-01

111

Changes in lipid profile variables in response to submaximal and maximal exercise in trained cyclists.  

PubMed

This study examined the effect of prolonged submaximal exercise followed by a self-paced maximal performance test on cholesterol (T-Chol), triglycerides (TG), and high-density lipoprotein cholesterol (HDLC). Nine trained male athletes cycled at 70 percent of maximal oxygen consumption for 60 min, followed by a self-paced maximal ride for 10 min. Venous blood samples were obtained at rest, at 30 and 60 min during submaximal exercise, and immediately after the performance test. Lactic acid, haematocrit (Hct), haemoglobin (Hb), T-Chol and TG were measured in the blood, while plasma was assayed for HDL-C. Plasma volume changes in response to exercise were calculated from Hct and Hb values and all lipid measurements were corrected accordingly. In order to ascertain the repeatability of lipid responses to exercise, all subjects were re-tested under identical testing conditions and experimental protocols. When data obtained during the two exercise trials were analysed by two-way ANOVA no significant differences (P > 0.05) between tests were observed. Consequently the data obtained during the two testing trials were pooled and analysed by one-way ANOVA. Blood lactic acid increased nonsignificantly (P > 0.05) during the prolonged submaximal test, but rose markedly (P <0.05) following the performance ride. Lipid variables ascertained at rest were within the normal range for healthy subjects. ANOVA showed that blood T-Chol and TG were unchanged (P > 0.05), whereas HDL-C rose significantly (P <0.05) in response to exercise. Post hoc analyses indicated that the latter change was due to a significant rise in HDL-C after the performance ride. It is concluded that apparent favourable changes in lipid profile variables occur in response to prolonged submaximal exercise followed by maximal effort, and these changes showed a good level of agreement over the two testing occasions. PMID:8861674

El-Sayed, M S; Rattu, A J

1996-01-01

112

Serum Uric Acid and Cholesterol Variability: A Comprehensive View of Underwater Demolition Team Training.  

National Technical Information Service (NTIS)

One-third of a Navy underwater demolition team training class (32 men) was investigated by thrice weekly psychological assessment and serum uric acid and cholesterol determinations until they either dropped from training or graduated. In general, signific...

R. H. Rahe R. T. Rubin R. J. Arthur B. R. Clark

1968-01-01

113

Aortic valve replacement with stentless and stented porcine valves: a case-match study  

Microsoft Academic Search

Objectives: To assess the potential benefits of the hemodynamic superiority of stentless valves, we conducted a case-match study among patients who underwent aortic valve replacement with two types of porcine bioprostheses: the Toronto SPV and the stented Hancock II bioprosthesis. Methods: Preoperative clinical variables predictive of death after aortic valve replacement were determined by a stepwise logistic regression analysis in

Tirone E. David; Rudolph Puschmann; Joan Ivanov; Joanne Bos; Susan Armstrong; Christopher M. Feindel; Hugh E. Scully

1998-01-01

114

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

115

Separator valve  

SciTech Connect

A valve is described for separating liquids out of gases, as in gas-well-to-customer operations, being an improvement of the valve described in our U.S. Pat. No. 3,769,999 of Nov. 6, 1973, entitled ''liquid separator system and apparatus''. The valve is comprised of body with enlarged inlet chamber, a rising passage communicating therewith, a circumferential groove about the rising passage, downwardly extending passages spaced on opposite sides of the rising passage and extending to an outlet chamber. The valve includes a head chamber with floating disc positioned within the same and seating atop the rising passage and circumferential groove, the floating disc being provided on the underside thereof with a radial groove to bleed off fluid in the head chamber and one or more further grooves to control fluid coming from the rising passage. A spring also is positioned within the head chamber, eccentrically pressing on the disc to permit instantaneous filling of head chamber under gas operation and quick closing of the valve under head pressure. An outlet fitting engages the valve in communication with the outlet chamber, the fitting being provided with central orifice to effect desired back pressure under gas operation.

Carter, J.L.; Flanagan, J.P.

1981-05-26

116

Repetitive control of an electro-hydraulic engine valve actuation system  

Microsoft Academic Search

Fully flexible engine valve systems serve as powerful rapid prototyping tools in research laboratories. With the ability to quickly design innovative valve strategies, researchers can explore the possibilities of improving fuel efficiency, power output and emissions through appropriately varying the valve lift, phasing and timing. One means of achieving variable valve motion is through an electro-hydraulic valve system (EHVS). However,

Hsien-Hsin Liao; Matthew J. Roelle; J. Christian Gerdes

2008-01-01

117

TRAINING COMMUNITY VOLUTEERS IN PREVENTING ALCOHOLISM AND DRUG ADDICTION : A BASIC PROGRAMME AND ITS IMPACT ON CERTAIN VARIABLES  

PubMed Central

A study was conducted on 19 community volunteers and the training module they underwent is presented. The subjects were given 7 days in-training with the objectives of imparting knowledge ana skill to identify and motivate alcohol and drug dependent person, to motivate them and their family to seek treatment to provide social support to them and to organise prevention programmes in the community. Their knowledge, skills and attitudes have shown significant improvement and change as a result to training. Extraversion was found to be significantly related to change in all the above variables, psychoticism was related to attitude and self-esteem was related to improvement in skills. Need for under taking further research in this area is also emphasized.

Manickam, L.S.S.

1997-01-01

118

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

119

Pneumatic valve return  

SciTech Connect

A reciprocating piston internal combustion engine is described having a cylinder head and intake exhaust valves operated by a cam-driven actuation mechanism, each valve having a valve head for engaging a valve seat in the cylinder head and a valve stem attached to the valve head and extending through and out of the cylinder head to be engaged by the actuation mechanism, the valve stem being supported for reciprocating motion by a valve guide in the cylinder head so that the valve is movable between a closed position with the valve head in contact with the valve seat and an open position with the valve head being spaced-apart from the valve seat and the valve stem being moved inwardly into the cylinder head by the actuation mechanism, the actuation mechanism operating each valve through a cycle in which the valve is in the closed position longer than it is in the open position.

Speckhart, F.H.

1986-06-03

120

VO2 Max in Variable Type Exercise Among Well-Trained Upper Body Athletes.  

ERIC Educational Resources Information Center

The maximal oxygen consumption (VO2 max) of well-trained upper body athletes was compared to that of untrained individuals in four types of exercise: arm cranking, legs only cycling, graded treadmill running, and combined arm cranking and leg cycling. Results of the study showed that well-trained upper body athletes attained a significantly higher…

Seals, Douglas R.; Mullin, John P.

1982-01-01

121

Variability of Practice and the Transfer of Training of Motor Skills.  

National Technical Information Service (NTIS)

The Training and Simulation Technical Area of the U.S. Army Research Institute for the Behavioral and Social Sciences (ARI) maintains a program of research in support of the systems approach to training. A major focus of this program is the development of...

C. A. Wrisberg T. P. Winter

1983-01-01

122

Management turnover expectations: a variable to explain company readiness to engage in continuous management training  

Microsoft Academic Search

What makes companies give their support to Continuous Management Training (CMT) and why, on occasion, do they block its progress? If a company thinks its managers might leave in the near future, would there be reasons for it to provide continuous training of these professionals? Do companies interpret all likely resignations in the same way? We attempt to provide an

Jon Landeta; Jon Barrutia; Jon Hoyos

2009-01-01

123

VO2 Max in Variable Type Exercise Among Well-Trained Upper Body Athletes.  

ERIC Educational Resources Information Center

|The maximal oxygen consumption (VO2 max) of well-trained upper body athletes was compared to that of untrained individuals in four types of exercise: arm cranking, legs only cycling, graded treadmill running, and combined arm cranking and leg cycling. Results of the study showed that well-trained upper body athletes attained a significantly…

Seals, Douglas R.; Mullin, John P.

1982-01-01

124

Changes in inflammatory activity, heart rate variability, and biochemical indices in young athletes during the annual training cycle  

Microsoft Academic Search

Inflammatory activity, heart rate variability (HRV), and biochemical and functional indices were assessed in young ski racers\\u000a during the preparation, competition, and recovery periods of an annual training cycle. During the preparation period, autohemodilution\\u000a (decreased red blood cell count (RBC) and hematocrit (Ht) levels) and a decrease in the systemic inflammatory activity (C-reactive\\u000a protein) occurred, without significant differences in the

A. A. Kylosov; A. A. Mel’nikov; A. Yu. Mal’tsev; A. D. Vikulov; O. L. Borisova

2009-01-01

125

Regulator valve  

US Patent & Trademark Office Database

A regulator valve is structured such that hydraulic pressure to be output from a regulated pressure output port is regulated according to urging forces, i.e., line pressure to be regulated, throttle pressure, spring force from a compression coil spring, and operating force from a plunger, which are applied to a valve spool. The plunger has a small diameter portion and a large diameter portion having a diameter larger than the diameter of the small diameter portion, both of which are axially displaceably retained in a spring receiving sleeve. The small diameter portion is urged in one axial direction at one end of the plunger that protrudes into a spring chamber and faces the valve spool, while the large diameter portion is urged in the other axial direction by range pressure at the other end of the plunger which is isolated from the small diameter portion located in the spring chamber.

2012-12-11

126

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.

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

2012-01-01

127

Metabolic and performance responses to constant-load vs. variable-intensity exercise in trained cyclists.  

PubMed

We studied glucose oxidation (Glu(ox)) and glycogen degradation during 140 min of constant-load [steady-state (SS)] and variable-intensity (VI) cycling of the same average power output, immediately followed by a 20-km performance ride [time trial (TT)]. Six trained cyclists each performed four trials: two experimental bouts (SS and VI) in which muscle biopsies were taken before and after 140 min of exercise for determination of glycogen and periodic acid-Schiff's staining; and two similar trials without biopsies but incorporating the TT. During two of the experimental rides, subjects ingested a 5 g/100 ml [U-(14)C]glucose solution to determine rates of Glu(ox). Values were similar between SS and VI trials: O(2) consumption (3.08 +/- 0.02 vs. 3.15 +/- 0.03 l/min), energy expenditure (901 +/- 40 vs. 904 +/- 58 J x kg(-1) x min(-1)), heart rate (156 +/- 1 vs. 160 +/- 1 beats/min), and rating of perceived exertion (12.6 +/- 0.6 vs. 12.7 +/- 0.7). However, the area under the curve for plasma lactate concentration vs. time was significantly greater during VI than SS (29.1 +/- 3.9 vs. 24.6 +/- 3. 7 mM/140 min; P = 0.03). VI resulted in a 49% reduction in total muscle glycogen utilization vs. 65% for SS, while total Glu(ox) was higher (99.2 +/- 5.3 vs. 83.9 +/- 5.2 g/140 min; P < 0.05). The number of glycogen-depleted type I muscle fibers at the end of 140 min was 98% after SS but only 59% after VI. Conversely, the number of type II fibers that showed reduced periodic acid-Schiff's staining was 1% after SS vs. 10% after VI. Despite these metabolic differences, subsequent TT performance was similar (29.14 +/- 0.9 vs. 30.5 +/- 0.9 min for SS vs. VI). These results indicate that whole body metabolic and cardiovascular responses to 140 min of either SS or VI exercise at the same average intensity are similar, despite differences in skeletal muscle carbohydrate metabolism and recruitment. PMID:10484594

Palmer, G S; Borghouts, L B; Noakes, T D; Hawley, J A

1999-09-01

128

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

129

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

130

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

131

Prediction by Career Field of First Term Airman Performance from Selection and Basic Training Variables.  

National Technical Information Service (NTIS)

To gain information that might be useful in improving airman classification, 29 predictor variables were evaluated by multiple regression techniques against a criterion of satisfactory performance during the first 2 years of enlistment. Variables included...

E. S. Flyer

1964-01-01

132

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

133

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

134

Modular, self-contained hydraulic valve timing systems for internal combustion engines  

Microsoft Academic Search

A modular self-contained hydraulic variable valve timing system for use with an internal combustion engine of the type having an engine block which includes a rotatable cam shaft, and sets of intake and exhaust valves respectively operatively associated with combustion cylinders of the engine. The modular self-contained variable valve timing system comprising: a valve cover adapted to being coupled to

Wakeman

1989-01-01

135

Seasonal training and heart rate and blood pressure variabilities in young swimmers  

Microsoft Academic Search

To evaluate if changes in athletes’ physical fitness due to seasonal training are associated with changes in cardiovascular autonomic control, nine swimmers (three males and six females; aged 14–18 years) were evaluated before and after 5 months of training and competitions. Maximal oxygen consumption\\u000a$$(\\\\dot {V} \\\\hbox{O}_{2\\\\max})$$ and ventilatory threshold were determined during a maximal test; heart rate (HR) and blood pressure

Renza Perini; Adelaide Tironi; Michela Cautero; Antonio Di Nino; Enrico Tam; Carlo Capelli

2006-01-01

136

Effects of resistance training on biomarkers of bone formation and association with red blood cell variables  

Microsoft Academic Search

We previously showed that resistance training significantly increased the red blood cell count (RBC) and hematocrit (Hct)\\u000a and decreased the mean cell hemoglobin concentration (MCHC) in physically inactive men. Since the enhanced hematopoiesis may\\u000a result, at least partly, from bone metabolism, the purpose of this study was to further investigate the effect of resistance\\u000a training on serum bone-specific alkaline phosphatase

Min Hu; Taija Finni; Leiting Xu; Liangchou Zou; Sulin Cheng

137

Dump valve  

Microsoft Academic Search

A swab assembly is provided having a dump valve responsive to fluid pressure and drag which will dump the fluid load should either fluid load or drag or the effect of both fluid load and drag become abnormal. Also if the fluid pressure and\\/or drag become abnormal, the fluid load on the cup will be released and wash away foreign

1981-01-01

138

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

139

The validity of physiological variables to assess training intensity in kayak athletes.  

PubMed

It appears that training benefits are compromised if excessive training is performed at intensities that are either too low or too high. This suggests a need for accurate methods to monitor training intensity. It has been suggested that heart rate (HR) or lactate concentration ([La -]) can be used to accurately monitor training intensity. The purpose of the present study therefore, was to examine whether the relationship between HR, [La -] and intensity determined during a kayak graded exercise test (GXT) remained stable during constant-intensity kayak exercise. Sixteen trained kayak paddlers, (22 +/- 4 y, peak V.O (2) = 3.7 +/- 0.9 l x min (-1)) performed a GXT on a wind-braked kayak ergometer. They then performed a 20-min constant-load test on the kayak ergometer at a power output corresponding to their lactate inflection (LI) intensity. Eight subjects also performed a 20-min constant-load test at a power output corresponding to their lactate threshold (LT) intensity. Differences between constant-load and GXT values were determined using one-way ANOVA (p < 0.05). There were no significant differences between values for HR and V.O (2) derived from the GXT and those measured during both constant-load tests. However, while [La -] also provided a valid marker of the LI training intensity (1.8 +/- 0.3 v 2.1 +/- 0.8 mmol x l (-1)), [La -] did not provide a valid marker of the LT training intensity (3.8 +/- 0.7 v 5.1 +/- 1.4 mmol x l (-1)). These results suggest that HR, but not [La -1], is similar during both a GXT and constant-load exercise at the LT intensity. PMID:14750016

Bishop, D

2004-01-01

140

Variables  

NSDL National Science Digital Library

This site, presented by Statistics Canada, is a section from "Statistics: Power from Data!" on variable classification. It discusses categorical and numerical variables and their types. The site discusses these variables: nominal, ordinal, numeric, continuous, and discrete. This is a good introductory site for any mathematics classroom studying statistics.

2008-12-25

141

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.

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

2011-01-01

142

Effects of practice on variability in an isochronous serial interval production task: asymptotical levels of tapping variability after training are similar to those of musicians.  

PubMed

Timing permeates everyday activities such as walking, dancing and music, yet the effect of short-term practice in this ubiquitous activity is largely unknown. In two training experiments involving sessions spread across several days, we examined short-term practice effects on timing variability in a sequential interval production task. In Experiment 1, we varied the mode of response (e.g., drumstick and finger tapping) and the level of sensory feedback. In Experiment 2 we varied the interval in 18 levels ranging from 500 ms to 1624 ms. Both experiments showed a substantial decrease in variability within the first hour of practice, but little thereafter. This effect was similar across mode of response, amount of feedback, and interval duration, and was manifested as a reduction in both local variability (between neighboring intervals) and drift (fluctuation across multiple intervals). The results suggest mainly effects on motor implementation rather than on cognitive timing processes, and have methodological implications for timing studies that have not controlled for practice. PMID:23558155

Madison, Guy; Karampela, Olympia; Ullén, Fredrik; Holm, Linus

2013-04-01

143

Testing mediator variables in a resistance training intervention for obese adults with type 2 diabetes  

Microsoft Academic Search

A poor understanding of behaviour change mechanisms has hindered the development of effective physical activity interventions. The aim of this study was to identify potential mediators of change in a home-based resistance training (RT) program for obese individuals with type 2 diabetes. Obese individuals with type 2 diabetes (N?=?48) were randomly allocated to either an RT intervention (n?=?27) or a

David R. Lubans; Ronald C. Plotnikoff; Mary Jung; Neil Eves; Ron Sigal

2011-01-01

144

ELECTROSTRICTION VALVE  

DOEpatents

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

Kippenhan, D.O.

1962-09-25

145

Respiratory compensation and blood pH regulation during variable intensity exercise in trained versus untrained subjects  

Microsoft Academic Search

To determine whether endurance-trained cyclists (T; n = 10) have a superior blood-respiratory buffering for metabolic acidosis relative to untrained subjects (UT; n = 10) during variable intensity exercise (VAR). On three occasions, T and UT pedaled for 24 min alternating high- and low-intensities\\u000a as percentage of their second ventilatory threshold (VT2): VARLOW 87.5–37.5% VT2, VARMODERATE 125–25% VT2, and VARHIGH 162.5–12.5% VT2 to complete the

Juan Del Coso; Nassim Hamouti; Roberto Aguado-Jimenez; Ricardo Mora-Rodriguez

2009-01-01

146

VAPOR VALVE  

DOEpatents

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

Wouters, L.F.

1959-08-25

147

Metabolic and performance responses to constant-load vs variable-intensity exercise in trained cyclists  

Microsoft Academic Search

The results of this study indicate that whole body metabolic and cardiovascular responses to 140 min of either steady state or variable intensity exercise at the same average intensity are similar, despite differences in skeletal muscle carbohydrate metabolism and recruitment

GARRY S. PALMER; LARS B. BORGHOUTS; TIMOTHY D. NOAKES; JOHN A. HAWLEY

1999-01-01

148

Design and Dynamic Simulation of a Fixed Pitch 56 kW Wind Turbine Drive Train with a Continuously Variable Transmission.  

National Technical Information Service (NTIS)

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 g...

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

1986-01-01

149

Earthquake relief valve  

SciTech Connect

A shock actuated shut-off valve is described, comprising: a valve, having an open position and a closed position, rotatably mounted within a valve body; a valve stem connected to the valve; an elongated handle having a valve stem engagement end and a ball detent engagement end, the valve stem engagement end connected to the valve stem; means for urging the valve to rotate into the closed position; means for stopping further rotation of the valve when the valve is in the closed position; a ball detent; and a pendulum having a ball detent engagement end and a plumb end, the ball detent engagement end supporting the second ball, the pendulum responding to a shock by freeing the second ball, thereby freeing the elongate handle and allowing the valve to move to the closed position.

Diamond, H.E.

1989-04-18

150

The Role of Aerobic and Anaerobic Training Programs on CD(34+) Stem Cells and Chosen Physiological Variables.  

PubMed

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

2012-12-30

151

Implementation and Analysis of a Repetitive Controller for an Electro-Hydraulic Engine Valve System  

Microsoft Academic Search

Variable valve actuation plays an important role in modern engine design. Fuel economy, emissions, and power output can be improved through appropriately varying valve lift and timing. One means of independently and continuously adjusting these valve profile parameters is with an electro-hydraulic valve system (EHVS). However, with an EHVS, it is very difficult to achieve the same level of accurate

Hsien-Hsin Liao; Matthew J. Roelle; Jyh-Shin Chen; J. Christian Gerdes

2011-01-01

152

Mitral valve replacement with ball valve prostheses  

Microsoft Academic Search

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

Albert Starr

1971-01-01

153

The effect of endurance training on resting heart rate variability in sedentary adult males  

Microsoft Academic Search

.   Eleven previously sedentary adult males, serving as the experimental (EXP) group [mean (SE) age 36.6 (1.7) years, body mass\\u000a 87.2 (4.3) kg, body mass index, BMI, 28.4 (1.5) kg·m–2] participated in a 16-week supervised exercise program (3 days·week–1, 30 min·day–1, at ?80% of heart rate reserve) to determine the temporal effects of a moderate-to-vigorous-intensity exercise program on\\u000a heart rate variability (HRV). Five sedentary males

Edward L. Melanson; Patty S. Freedson

2001-01-01

154

Interval training in elderly men increases both heart rate variability and baroreflex activity  

Microsoft Academic Search

\\u000a Abstract\\u000a \\u000a Aims\\u000a   Autonomic nervous system activity decreases continuously with age and appears to be a powerful predictor of disease and death. Attempts are thus made to reactivate autonomic drive with the intent of improving health.\\u000a Methods\\u000a   We assessed maximal oxygen consumption (VO2max), auto- nomic nervous system activity by heart rate variability (HRV) analysis and spontaneous cardiac baroreflex activity (SBR) in

Vincent Pichot; Frédéric Roche; Christian Denis; Martin Garet; David Duverney; Frédéric Costes; Jean-Claude Barthélémy

2005-01-01

155

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

156

Mitral Valve Prolapse  

MedlinePLUS

Mitral valve prolapse (MVP) occurs when one of your heart's valves doesn't work properly. The flaps of the valve are "floppy" and don't close tightly. Most ... can leak the wrong way through the floppy valve. This can cause Palpitations (feelings that your heart ...

157

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

158

Drill string safety valve  

SciTech Connect

A multi position safety valve is disclosed retainable within an internal portion of a drill string casing (s) and responsive to the greater differential pressure in an internal fluid passage to displace a valve head relative to a valve seat (VS) from its normal partially open position to either a wide open or a closed position. The valve head is attached to a valve stem that extends through a valve chamber and slideably mounted in opposite closed ends of a valve body and returnable to and maintained in the partially open position by opposing compression springs situated between opposite ends of the valve body and one side of an intermediate abutment of the valve stem and an intervening disc on the opposite side thereof. The disc 38 is moveable into and out of seating engagement with an intermediate stop by one spring and the intermediate abutment of the valve stem respectively.

Aumann, J.T.

1983-07-05

159

Determining valve position  

SciTech Connect

A method and apparatus for determining the position of a valve for example ball valves, plug valves, gate valves using a source of radiation such as cesium-137 located either on or adjacent to the external surface of the valve or within the valve itself, for example in the ball of a ball valve, and a radiation detector such as a Geiger-Muller tube on the external surface of the valve. Source and detector are aligned and located relative to one another so that the count rate detected is indicative of the valve position. The method is accurate and, for example, allows the position of the ball in a ball valve to be monitored to within /sub +/ or /sub -/1 mm.

Hurst, J.A.; Jackson, P.

1984-08-28

160

Prosthetic Heart Valves  

Microsoft Academic Search

\\u000a The development of prosthetic heart valves has been a major advance in the treatment of patients with valvular heart disease.\\u000a There have been ongoing improvements in valve design so that the performance and durability of the currently available heart\\u000a valves far surpasses early generation valve prostheses. Despite the major improvements in prosthetic heart valves and the\\u000a positive impact on outcome

Kwan-Leung Chan; John P. Veinot

161

Valve for subterraneal wells  

SciTech Connect

The invention relates to an improved subterranean well safety valve wherein an annular actuator is moved downwardly by applied fluid pressure to effect the opening movement of a valve head of a valve relative to an annular valve seat. The initial downward movement of the actuator effects the displacement of a valve stem which extends through a restricted aperture in the valve head, moving a ball valve segment on the valve stem from a seat in the aperture, thus permitting the bleeding of any fluid pressure differential existing on the lower side of the valve head relative to the upper side and reducing the amount of force required to move the valve to its open position. Additionally, in one embodiment, a locking sleeve is slidably mounted within the shiftable annular actuator and such sleeve is operable by an auxiliary tool to effect the radial shifting of locking elements carried by the actuator into locking engagement with the valve housing to achieve a temporary locking of the valve in an open position. The travel of the locking sleeve relative to the valve housing in a reverse direction is limited by a shearable pin so that reverse forcible movement of the locking sleeve will shear the pin and effect a permanent locking of the radially expansible locking segments carried by the actuating sleeve to the valve housing, thus permanently locking the valve in an open position.

Akkerman, N. H.

1984-10-09

162

Lubricator valve apparatus  

SciTech Connect

A lubricator valve assembly comprises a reciprocably rotatable ball valve which is operated between open and closed positions solely through the selective application of control pressures and/or tubing pressure above the valve to a double acting sleeve type actuating piston. One end of the actuating piston has a valving piston formed thereon which cooperates with a seal bore in the housing to effect the opening or closing of a bypass fluid passage extending from a region below the ball valve to a region above the ball valve. Such valving piston also functions as part of a lost motion connection between the actuating sleeve piston and a reciprocable actuator for rotating the ball valve. In opening the ball valve, the valving piston first moves upwardly to establish a fluid bypass around the closed ball valve and then establishes contact with the actuator to rotate the ball valve to an open position. The same fluid bypass may be utilized to pump through fluid around the closed ball valve by applying fluid pressure above the ball valve. Improved sealing elements for the ball valve are also provided.

Brooks, R. T.

1984-10-16

163

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

164

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

PubMed

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. PMID:19391776

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

2009-02-06

165

Rorschach variables and Big Five scales as predictors of military training completion: a replication study of the selection of candidates to the naval special forces in Norway.  

PubMed

We tested 140 male candidates at the Naval Special Forces (NFS) of Norway on the Rorschach (Exner, 2003; Rorschach, 1921/1942) and the Norwegian version of the Big Five personality dimensions (Engvik & Føllesdal, 2005). Rorschach variables significantly correlated with training completion (effect sizes of r(e) = .14-.25), whereas none of the Big Five factors or facets did. The combination of Rorschach and Big Five variables framed in the illusory mental health concept provided strong predictive ability. Testing under stress produced slightly higher predictive validity coefficients between the Rorschach variables and pass-fail than under calm testing. The findings support the results of Hartmann, Sunde, Kristensen, and Martinussen (2003), indicating that Rorschach variables and indications of good mental health may be valid predictors of NFS training. PMID:19365766

Hartmann, Ellen; Grønnerød, Cato

2009-05-01

166

Robotic mitral valve surgery.  

PubMed

A renaissance in cardiac surgery has begun. The early clinical experience with computer-enhanced telemanipulation systems outlines the limitations of this approach despite some procedural success. Technologic advancements, such as the use of nitinol U-clips (Coalescent Surgical Inc., Sunnyvale, CA) instead of sutures requiring manual knot tying, have been shown to decrease operative times significantly. It is expected that with further refinements and development of adjunct technologies, the technique of computer-enhanced endoscopic cardiac surgery will evolve and may prove to be beneficial for many patients. Robotic technology has provided benefits to cardiac surgery. With improved optics and instrumentation, incisions are smaller. The ergometric movements and simulated three-dimensional optics project hand-eye coordination for the surgeon. The placement of the wristlike articulations at the end of the instruments moves the pivoting action to the plane of the mitral annulus. This improves dexterity in tight spaces and allows for ambidextrous suture placement. Sutures can be placed more accurately because of tremor filtration and high-resolution video magnification. Furthermore, the robotic system may have potential as an educational tool. In the near future, surgical vision and training systems might be able to model most surgical procedures through immersive technology. Thus, a "flight simulator" concept emerges where surgeons may be able to practice and perform the operation without a patient. Already, effective curricula for training teams in robotic surgery exist. Nevertheless, certain constraints continue to limit the advancement to a totally endoscopic computer-enhanced mitral valve operation. The current size of the instruments, intrathoracic instrument collisions, and extrathoracic "elbow" conflicts still can limit dexterity. When smaller instruments are developed, these restraints may be resolved. Furthermore, a working port incision is still required for placement of an atrial retractor, as well as needle, tissue, and suture retrieval. With the development of specialized retractors and a delivery/retrieval port, a truly endoscopic approach will be consistently reproducible. New navigation systems and image guided surgery portend an improving future for robotic cardiac surgery. Recently, we have combined robotically guided microwave catheters for ablation of atrial fibrillation with robotic mitral valve repairs (Fig. 8). Thus, we are beginning to achieve the ideal operation, with a native valve repair and a return to normal sinus rhythm. Robotic cardiac surgery is an evolutionary process, and even the greatest skeptics must concede that progress has been made toward endoscopic cardiac valve operations. Surgical scientists must continue to critically evaluate this technology in this new era of cardiac surgery. Despite enthusiasm, caution cannot be overemphasized. Surgeons must be careful because indices of operative safety, speed of recovery, level of discomfort, procedural cost, and long-term operative quality have yet to be defined. Traditional valve operations still enjoy long-term success with ever-decreasing morbidity and mortality, and remain our measure for comparison. Surgeons must remember that we are seeking the most durable operation with the least human trauma and quickest return to normalcy, all done at the lowest cost with the least risks. Although we have moved more asymptotically to these goals, surgeons alone must map the path for the final ascent. PMID:14712874

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

2003-12-01

167

20. VAL, DETAIL OF QUICKACTING VALVE (QAV) ABOVE COMPRESSION TANK ...  

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

20. VAL, DETAIL OF QUICK-ACTING VALVE (QAV) ABOVE COMPRESSION TANK ON THE LAUNCHER BRIDGE. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

168

Ball valve extractor  

DOEpatents

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

Herndon, Charles (Walterboro, SC); Brown, Roger A. (North Augusta, SC)

2002-01-01

169

Effects of aerobic training intensity on resting, exercise and post-exercise blood pressure, heart rate and heart-rate variability  

Microsoft Academic Search

We aimed to investigate the effects of endurance training intensity (1) on systolic blood pressure (SBP) and heart rate (HR) at rest before exercise, and during and after a maximal exercise test; and (2) on measures of HR variability at rest before exercise and during recovery from the exercise test, in at least 55-year-old healthy sedentary men and women. A

V A Cornelissen; B Verheyden; A E Aubert; R H Fagard

2010-01-01

170

Transjugular Tricuspid Valve-in-Valve Implantation.  

PubMed

A 60 year-old female underwent tricuspid valve replacement in 2002. Post-operative recovery was complicated by severe post-pericardiotomy-syndrome. Seven years later she underwent transcatheter valve-in-valve implantation through the right jugular vein because of early prosthesis deterioration. Moreover intra-operative transoesophageal echocardiography showed an important right-to-left shunt through the patent foramen ovale that immediately disappeared after the deployment of a 29-mm Sapien-XT. The patient had an immediate and dramatic improvement in day-by-day activities. This case shows that tricuspid valve deterioration can be safely and successfully treated through this approach. PMID:23726665

Salizzoni, Stefano; La Torre, Michele; Barbero, Cristina; Marra, Walter Grosso; Moretti, Claudio; D'Amico, Maurizio; Rinaldi, Mauro

2013-05-29

171

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

SciTech Connect

This report covers the dynamic analysis of a horizontal axis fixed pitch wind turbine generator (WTG) that is rated at 56 kW. 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.

1986-03-01

172

Ride Comfort Analysis based on Heart Rate and Blood Pressure Variability according to Changed Tilting Angle at Tilting Train Simulator  

Microsoft Academic Search

The Korea is consisted of 70% mountain terrain and at existing rail road, it is many of curve railroad segment naturally. If tilting train is applied, it is unnecessary that speed of tilting train is supposed to decelerating in the curve railroad segment. As you get a hunch as term 'tilting', the biggest feature of tilting train is the thing

Kwangsoo Shin; Youngbum Lee; Yongsoo Song; Sungho Han; Myoungho Lee

2008-01-01

173

[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

174

Heart Valves Explained  

MedlinePLUS

... repaired. The American Heart Association does not conduct technical review of mechanical heart valves. The U.S. Food ... forming. The American Heart Association does not conduct technical review of mechanical heart valves. The U.S. Food ...

175

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

176

Oil well standing valve  

SciTech Connect

A standing valve which may be retrievably mounted in a well production tubing and will allow the maximum possible fluid flow and also allow the valve to be easily drained and retrieved through the well production tubing. The seal between the standing valve and the bottom hole assembly is located at or below the level of the seat and fluid from the top of the valve into the well is drained through the seat.

Holland, R. A.; Brennan, J. R.; Christ, F. C.; Petrie, H. L.

1985-05-28

177

Rotary valve shaft  

SciTech Connect

This patent describes a rotary valve shaft for use with an internal combustion engine having a combustion chamber port, the rotary valve shaft including at least one gas passage means. It comprises groove on the periphery of the rotary valve shaft and a means for connecting the groove with the port upon rotation of the rotary valve shaft, wherein the connecting means comprising notch adjacent to and leading into the groove.

Lynch, R.M.

1992-07-07

178

Ball valves solve turbine drain valve problem  

SciTech Connect

Alabama Power's E.C. Gaston generating plant, a 1904-MW facility located 40 miles south of Birmingham, consists of four 250-MW units, one 884-MW unit, and a 20-MW combustion turbine. Over the years the utility has experienced recurring failure of turbine drain valves on Gaston Unit 5. Unit 5 uses a Combustion Engineering supercritical steam generator rated at 6,351,470 lb/hr main steam flow to deliver steam to a General Electric tandem-compound reheat turbine with a rated capacity of 884 MW at 3500 psig and 1000 F. Main steam enters the turbine through four combined stop and control valves mounted independent of the turbine shell. This paper reports that each stop and control valve is equipped with two before-seat drain valves. One of the drain valves is motor-operated to facilitate remote operation: the other is a manual valve. In an effort to improve drain systems and reduce costs, alternatives to the problem-ridden Y-pattern glove valves were investigated. One such alternative was the Mogas severe-service metal-seated ball valve.

McDaniel, P. (Alabama Power Co., Birmingham, AL (United States))

1992-01-01

179

Transfusion and hematologic variables after fibrinogen or platelet transfusion in valve replacement surgery: preliminary data of purified lyophilized human fibrinogen concentrate versus conventional transfusion.  

PubMed

BACKGROUND: Platelet (PLT) and plasma transfusion remain the mainstay hemostatic therapy for perioperative bleeding. Several studies have indicated that acquired fibrinogen (FIB) deficiency can be the primary cause of bleeding after cardiac surgery. The aim of this study was to compare hematologic and transfusion profiles between the first-line FIB replacement and PLT transfusion in post-cardiac surgical bleeding. STUDY DESIGN AND METHODS: In this prospective, randomized, open-label study, 20 adult patients who underwent valve replacement or repair and fulfilled preset visual bleeding scale were randomized to 4?g of FIB or 1 unit of apheresis PLTs. Primary endpoints included hemostatic condition in the surgical field and 24-hour hemostatic product usage. Hematologic data, clinical outcome, and safety data were collected up to the 28th day postoperative visit. RESULTS: In patients who received the first-line FIB concentrate (n?=?10), the visual bleeding scale improved after intervention, and the incidence of PLT transfusion and total plasma donor exposure were lower compared to the PLT group (n?=?10). Postintervention FIB level was statistically higher (209?mg/dL vs. 165?mg/dL) in the FIB group than in the PLT group, but PLT count and prothrombin were lower. There were no statistical differences in the postoperative blood loss and red blood cell transfusion between two groups. CONCLUSIONS: Our preliminary data indicate that the primary FIB replacement may potentially reduce the incidence of PLT transfusion and the number of donor exposures. Plasma FIB level of 200?mg/dL is attainable with a single dose of 4?g, and this level seems to mitigate bleeding despite moderately decreased thrombin generation. PMID:23718572

Tanaka, Kenichi A; Egan, Katherine; Szlam, Fania; Ogawa, Satoru; Roback, John D; Sreeram, Gautam; Guyton, Robert A; Chen, Edward P

2013-05-30

180

Mechanical heart valve cavitation: valve specific parameters.  

PubMed

Several aspects of mechanical heart valve cavitation, in particular of "severe" vapor cavitation, have been investigated in order to describe the phenomenon of cavitation itself and to classify various mechanical heart valves with respect to their tendency to cavitation. Furthermore, following the results of the measurements, a model for determination of time-dependent physical properties and dynamics of cavitation bubbles, such as size, pressure and temperature was developed. In order to classify the cavitation tendency of mechanical valves, a pulsatile hydraulic-driven circularly mock loop was used. Besides measurements of the relevant hemodynamic parameters, the leaflet velocities of the valves were also determined. In addition, numerous high-resolution pressure measurements, in particular the pressure drops necessary for the initiation of cavitation (local atrial pressure drop), were performed. For the investigation of bubble dynamics, a second pulsatile electro-magnetically-driven tester was used. The influence of density, viscosity and temperature of the fluid on the onset of cavitation was investigated. Cavitation events were recorded with a digital high-speed video camera (up to 40,500 frames/sec) for all investigated heart valves and under different conditions. A critical local upstream pressure drop (located within the model atrium after valve closure) of 450 mmHg was found for all valves as well as a valve specific correlation between left ventricular pressure gradient and local upstream pressure drop. Also, a valve dependent correlation between left ventricular pressure gradient and the local upstream pressure drop was provided. Finally, valve specific parameters were found to predict the cavitation tendency for a specific heart valve. The implementation of a suitable theoretical model allowed conclusions on bubble physics. High pressures (up to 800 bar) and temperatures (up to 1,300 degrees C) at bubble collapse have been determined. The influence of fluid parameters such as density, viscosity and temperature on the onset of cavitation is negligible within physiological range. Critical regions for cavitation for all mechanical heart valves were detected. All mechanical heart valves investigated show cavitation under different conditions (dp/dt) associated with high pressures and temperatures at bubble collapse. Cavitation bubble occurrence depends on valve design and location. PMID:15560680

Eichler, M J; Reul, H M

2004-10-01

181

Flow Control Valve.  

National Technical Information Service (NTIS)

A flow control valve for high temperature fluids is disclosed. The valve is characterized by an all-metal flow control unit including a tubular conduit, terminating in a valve seat, a throttling cone having an internal, truncated conical surface coaxially...

L. G. Hays

1974-01-01

182

Fuel distribution valve  

SciTech Connect

This patent describes a fuel flow distribution valve for dividing and metering fuel flow from a fuel source to nozzles for supplying fuel to an engine comprising valve body means having an inlet and outlets, intermediate liner means forming a longitudinal valve bore in the valve body means. The intermediate liner means has a reference surface thereon, a valve slidably supported in the valve bore slidable longitudinally therein and having a close tolerance diametral fit therewith. The valve has a positioning surface engageable with the reference surface and movable to a spaced apart position therefrom, spring means for biasing the valve in a first direction with respect to the liner means to engage the positioning surface and reference surface. The valve also has a means for directing inlet pressure against the valve in opposition to the spring means, pairs of in line-machined flow metering ports in the liner means and value with the ports in each pair being congruent by virtue of being machined simultaneously with a common tool in the liner means and the valve when the valve is in a fixed position in the bore with the positioning surface spaced a preselected longitudinal distance from the reference surface to define spaced pairs of congruent flow metering ports.

Halvorsen, R.M.; Hurst, J.B.

1986-09-30

183

Gas lift valve  

SciTech Connect

A gas lift valve is described which consists of: a body, a main valve seat in the body, a main valve member cooperable with the seat to control flow through the body, a pressure dome including a depending bellows connected to the valve member, the bellows being exposed to pressure within the dome urging the valve member toward the seat and to pressure exterior of the body urging the valve member away from the seat, an internal valve seat between the bellows and the remainder of the dome, an internal valve member separate from and movable relative to and supported on the main valve member and cooperable with the internal valve seat to control flow therethrough, one of the internal valve member and seat constructed of polyimide material, hydraulic fluid in the dome extending to a level above the internal valve seat, and a sleeve of polyimide material having a sliding engagement with the interior of the bellows and supporting the bellows against distortion when subjected to a differential pressure thereacross.

Hamm, E.J.

1986-06-03

184

Well safety valve  

SciTech Connect

A retrievable well safety valve in a cased well system including a tubing string, a dual packer downhole around the tubing sealing with the casing and submersible pump in the tubing string below the packer. The safety valve controls flow of pumped fluids through the tubing to surface and directs gas flow into the casing annulus above the packer. When the safety valve is landed in cooperating tubing nipples above the packer, separated central annular flow passages are formed for pumped fluids and gas respectively. A ball valve in the central flow passage controls pumped fluid flow therethrough and an annular valve coupled to the ball valve controls gas flow from below the packer through the annular flow passage around and by the ball valve. When the ball valve is in the down and open position, the valve ball member engages a lower seat, which maintains the central and annular flow passages separate and prevents comingling flow of fluids and gas. The coupled valves are held open by pressured fluid from surface and are closed automatically on loss of pressure in their control fluid circuits. When the valves close, a circuit of flow passages for recirculating pumped fluids and gas are opened below the ball valve and the pump may continue operation without overload.

Vinzant, M.B.; Hilts, R.L.; Meaders, M.; Speegle, S.C.

1984-07-24

185

Mechanical heart valve cavitation.  

PubMed

Cavitation was first directly related to mechanical heart valves in the mid 1980s after a series of valve failures observed with the Edwards-Duromedics valve. The damages observed indicated that cavitation could be responsible. Later, several in vitro studies visualized the bubble formation and collapse of cavitation at mechanical heart valves. It was suggested that cavitation could also cause damage to the formed elements of blood and thereby enhance the risk of thromboembolic complications seen in mechanical heart valve patients. Therefore, an applicable technique for in vivo detection of cavitation is required. This article reviews techniques developed for in vivo detection of cavitation and suggests focus for future studies. PMID:16293013

Johansen, Peter

2004-09-01

186

Pressure operated test valve  

SciTech Connect

A pressure operated test valve is described for use in a well test string in a well bore, the test string having a packer arranged for sealing the well bore to isolate the annulus between the well bore and the test string above the packer from that portion of the well bore below the packer. The valve consists of: a rotating ball valve movable between open and closed positions relative to the interior of the test string; a ball piston for shifting the rotating ball between the open and closed positions; biasing means for urging the ball piston to its valve closing position; a power fluid reservoir containing a power fluid; an axially shiftable power valve located within a power chamber, the power valve having opposed piston faces exposed by means of fluid passageways to fluid in the power fluid reservoir; and an axially slidable control valve located within a control chamber, the control valve having a pressure responsive annular area exposed to the power fluid for shifting the control valve and having internal passages for supplying pressurized power fluid to a selected face of the power valve to shift the power valve between a first position which isolates the ball piston and a second position which exposes the ball piston to annulus fluid pressure for shifting the ball to the open position.

Reardon, D.R.

1986-03-25

187

Pneumatic flow control valve using particle excitation by PZT transducer  

Microsoft Academic Search

This paper reports a flow control valve for pneumatic actuators. This flow control valve has a lightweight and simple structure using particle excitation by PZT transducer, which is driven at resonance mode and it can be used as a variable speed controller for pneumatic actuators. A PZT transducer has been used for controlling flow rate in this study. The flow

Daisuke Hirooka; Koichi Suzumori; Takefumi Kanda

2009-01-01

188

Guide to prosthetic cardiac valves  

SciTech Connect

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

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

1985-01-01

189

A low power, on demand electrothermal valve for wireless drug delivery applications.  

PubMed

We present a low power, on demand Parylene MEMS electrothermal valve. A novel Omega-shaped thermal resistive element requires low power (approximately mW) and enables rapid valve opening (approximately ms). Using both finite element analysis and valve opening experiments, a robust resistive element design for improved valve opening performance in water was obtained. In addition, a thermistor, as an inrush current limiter, was added into the valve circuit to provide variable current ramping. Wireless activation of the valve using RF inductive power transfer was demonstrated. PMID:20024057

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

2009-10-19

190

Dynamics and control of an electro-hydraulic fully flexible valve actuation system  

Microsoft Academic Search

As the internal combustion engine moves into the 21st century, fully flexible valve actuation (FFVA) systems are being proposed as an enabling technology for advanced internal combustion engine concepts. This paper focuses on exploring the dynamics and control of an electro-hydraulic fully flexible valve actuation system. Challenges and approaches for developing variable valve actuation systems are first outlined and discussed.

Zongxuan Sun; David Cleary

2003-01-01

191

Iterative learning control for soft landing of electromechanical valve actuator in camless engines  

Microsoft Academic Search

Variable valve timing allows improvements of internal combustion engines and can be achieved by camless actuation technology. In this paper we consider an electromechanical valve (EMV) actuator. One of the main problems in the EMV actuator is the noise and wear associated with high contact velocities during the closing and opening of the valve. The contact velocity of the actuator

Wolfgang Hoffmann; Katherine Peterson; Anna G. Stefanopoulou

2003-01-01

192

Gaseous fuel injector valve  

SciTech Connect

This patent describes in combination with a cylinder of an internal combustion engine having a liquid fuel inlet valve, an exhaust valve and a combustion chamber, a gaseous fuel inlet valve, a passage through the gaseous fuel inlet valve into the combustion chamber, a gaseous fuel line running to the passage, means in the passage normally closing the same, a programmed electronic sensing unit sensing the position of the crankshaft of the engine during the time of that part of a compression stroke in the cylinder after the exhaust valve therein is closed and prior to a rapid increase in compression therein, and means energized by the electronic sensing unit, upon the electronic sensing means sensing the closing of the exhaust valve, causing the means in the passage to open the passage into the combustion chamber to admit gaseous fuel therein.

Jensen, S.P.

1989-09-12

193

Long-Term Results After Starr-Edwards Mitral Valve Replacement in Children Aged 5 Years or Younger  

Microsoft Academic Search

Background. Mitral valve replacement with prosthetic valves in infants and children requires consideration of multiple variables. When we examined our late follow- up, the effect of the growth of the patient relative to the size of the prosthesis placed was the most important variable predicting late successful results. We reviewed our experience with mitral valve replacement using the Starr-Edwards ball

Ryuji Higashita; Seiichi Ichikawa; Hiroshi Niinami; Tetsuo Ban; Yuji Suda; Yasuo Takeuchi

2010-01-01

194

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

195

Robotic mitral valve surgery  

Microsoft Academic Search

Summary  BACKGROUND: Robotic mitral valve surgery has evolved and matured into a safe and reproducible procedure at multiple worldwide\\u000a centers of excellence. METHODS: History of robotic mitral valve repair is reviewed. Current results and recent advances are\\u000a discussed. RESULTS: Multiple trials have demonstrated that surgical outcomes for robotic mitral valve repair meet or exceed\\u000a the results of conventional operations, but long-term

E. J. Lehr; E. Rodriguez; L. W. Nifong; W. R. Chitwood

196

Biological heart valves.  

PubMed

Abstract Cardiac valvular pathologies are often caused by rheumatic fever in young adults, atherosclerosis in elderly patients, or by congenital malformation of the heart in children, in effect affecting almost all population ages. Almost 300,000 heart valve operations are performed worldwide annually. Tissue valve prostheses have certain advantages over mechanical valves such as biocompatibility, more physiological hemodynamics, and no need for life-long systemic anticoagulation. However, the major disadvantage of biological valves is related to their durability. Nevertheless, during the last decade, the number of patients undergoing biological, rather than mechanical, valve replacement has increased from half to more than three-quarters for biological implants. Continuous improvement in valve fabrication includes development of new models and shapes, novel methods of tissue treatment, and preservation and implantation techniques. These efforts are focused not only on the improvement of morbidity and mortality of the patients but also on the improvement of their quality of life. Heart valve tissue engineering aims to provide durable, "autologous" valve prostheses. These valves demonstrate adaptive growth, which may avoid the need of repeated operations in growing patients. PMID:24101369

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

2013-10-01

197

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

198

Retainer valve system  

SciTech Connect

In accordance with an illustrative embodiment of the present invention, a new and improved valve system for retaining production fluids in the subsea production pipe upon disconnection of the riser from the subsea wellhead during a production test of an offshore well includes a normally closed valve releasably connected to a normally open valve. The normally open valve can be hydraulically closed from a remote control station upon disconnection of the riser in order to retain fluids in the production pipe thereabove, and when closed will hold pressure in either longitudinal direction.

Young, D.E.

1981-03-03

199

Factitious Aortic Valve Insufficiency  

PubMed Central

One hundred consecutive aortograms, performed with careful attention to recommended technical details, were reviewed to identify cases of “factitious” aortic valve insufficiency, viz. aortic regurgitation seen during aortography for which there is no clinical evidence. Five patients with this condition were identified. Two of these subsequently underwent mitral valve replacement under cardiopulmonary by-pass. Aortic insufficiency was not detected during this procedure and the aortic valve appeared to be anatomically normal at postmortem examination. That factitious aortic insufficiency may exist should be remembered when aortography is used to differentiate aortic from pulmonary valve insufficiency. ImagesFig. 1Fig. 2Fig. 3Fig. 4

Kavanagh-Gray, Doris

1966-01-01

200

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

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

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

201

Retrofit Device for Alfalfa Valves.  

National Technical Information Service (NTIS)

The invention provides means to retrofit an alfalfa valve, without modification of the valve, to convert it from manual to pneumatic control. Alfalfa valves fitted with the invention have the characteristic of closing if the operating pressure is interrup...

C. H. Gibson D. A. Young

1986-01-01

202

Multiple Function CO2 Valve.  

National Technical Information Service (NTIS)

A compact fluid pressure regulation valve includes a valve body, the valve body having a pair of passageways, one passageway being a fluid pressure regulating passageway and the other passageway being a high pressure fluid supplying passageway. The fluid ...

L. J. Martini

1977-01-01

203

A study on the design of electromagnetic valve actuator for VVT engine  

Microsoft Academic Search

Electromagnetic valve (EMV) actuation system is a new technology for improving fuel efficiency and at the same time reducing\\u000a emissions in internal combustion engines. It can provide more flexibility in valve event control compared with conventional\\u000a variable valve actuation devices. The electromagnetic valve actuator must be designed by taking the operating conditions and\\u000a engine geometry limits of the internal combustion

Seung-hyun Park; Dojoong Kim; Byungohk Rhee; Jaisuk Yoo; Jonghwa Lee

2003-01-01

204

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

205

Evaluation of exhalation valves.  

PubMed

Certification tests currently employed by some industrialized nations to certify respirators require that when challenged with air flow at a constant suction head of 25 mmH2O, the leakage into the facepiece from the exhalation valve(s) should not exceed 30 ml min(-1). However, the test alone might not reflect the leakage rate under different levels of vacuum. To study the characteristics of leakage through exhalation valves, a leakage meter was built to measure the leakage rate of four brands of exhalation valves. Seven valves of each brand were tested for leakage rate at pressure drops ranging from 15 to 45 mmH2O (or extended to 75 mmH2O for some valves). Two types of leaks, i.e. fiber insertion and arch dent on the valve seat, were used to investigate the effect of leak shape on the characteristic leak flow as a function of pressure drop. A leakage data point represented a mean value of five measurements. The results showed that the leakage rate could increase or decrease with increasing pressure drop inside the respirators, indicating that the current method of conducting leakage tests, at a constant suction head of 25 mmH2O, does not guarantee better protection than when the respirators are used at a lower suction head. Moreover, based on the sample valves tested in this study, it was found that valve leakage was mostly caused by defects in the valve seats. Both fiber-insertion and arch-dent leaks had either increasing or decreasing characteristic curves, depending on the size of the leak and the material of the valve membrane. PMID:15716314

Kuo, Yu-Mei; Lai, Chane-Yu; Chen, Chih-Chieh; Lu, Bo-Hong; Huang, Sheng-Hsiu; Chen, Chun-Wan

2005-02-16

206

Transseptal Mitral Valve Replacement after Transcatheter Aortic Valve Implantation  

PubMed Central

We report a case of mitral valve replacement in a patient who had previously undergone transcatheter aortic valve implantation. A transseptal approach was used to avoid displacing the aortic prosthesis. Because of the small mitral annulus, a bioprosthetic aortic valve was used in reverse position for mitral valve replacement. The procedure did not interfere with the existing prosthesis, and a follow-up echocardiogram showed that both prosthetic valves were functioning well. To the best of our knowledge, this is the first report of mitral valve replacement in a patient who had a preceding transcatheter aortic valve implantation. We believe that the transseptal approach is promising for mitral valve replacement in such patients. Moreover, using a bioprosthetic aortic valve in reverse position is an option for mitral valve replacement when the mitral annulus is too small for placement of a standard bioprosthetic mitral valve.

Flannery, Laura D.; Lowery, Robert C.; Sun, Xiumei; Satler, Lowell; Corso, Paul; Pichard, Augusto; Wang, Zuyue

2012-01-01

207

49 CFR 192.145 - Valves.  

Code of Federal Regulations, 2012 CFR

...valve having shell (body, bonnet, cover...valves at their listed temperature. However, a valve...valves at their listed temperature, if: (1) The temperature-adjusted service...valve having shell (body, bonnet,...

2012-10-01

208

49 CFR 192.145 - Valves.  

Code of Federal Regulations, 2011 CFR

...valve having shell (body, bonnet, cover...valves at their listed temperature. However, a valve...valves at their listed temperature, if: (1) The temperature-adjusted service...valve having shell (body, bonnet,...

2011-10-01

209

Omni Valve Box Cover.  

National Technical Information Service (NTIS)

Metal valve box risers have led to performance problems when installed in bituminous concrete pavements in the past. Loss of ground support underneath the value box flange can occur which often results in settlement of the valve box. Traffic loading may a...

B. St. John T. Bartoski R. Sukley

1996-01-01

210

Bicuspid aortic valve  

MedlinePLUS

... leaflets, instead of three. The aortic valve regulates blood flow from the heart into the aorta, the major blood vessel that ... The aortic valve allows oxygen-rich blood to flow from the heart ... aorta into the heart when the pumping chamber relaxes. Bicuspid ...

211

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

212

No Valve in Vain  

NSDL National Science Digital Library

Acting as biomedical engineers, students design, build, test and redesign prototype heart valves using materials such as waterproof tape, plastic tubing, flexible plastic and foam sheets, clay, wire and pipe cleaners. They test them with flowing water, representing blood moving through the heart. As students creatively practice engineering problem solving, they demonstrate their understanding of how one-way heart valves work.

Techtronics Program

213

Heart valve bioprothesis  

US Patent & Trademark Office Database

A heart valve prosthesis has a supporting frame (22) with a circular cross-section, which is covered with a dacron fabric (23). On one end face the dacron fabric (23) is arranged to form a suture ring (14). The fixed aortic valve (15,16,17) of a kangaroo is attached inside the frame and sutured to the dacron fabric (23).

Reichart; Bruno (Munchen, DE); Weinhold; Christian (8000 Munchen 71, DE)

1986-12-02

214

Mud separator valve apparatus  

Microsoft Academic Search

An automatic cleaning system is provided for a mud separator apparatus. Water and mud inputs to a mud pump feeding the separator are respectively controlled by two butterfly valves ganged for cooperation, and operated by a single valve actuator motor. When the mud separator is shut off, a time delay relay is actuated which keeps the mud separator rotor motor

1981-01-01

215

Cavitation limits for valves  

Microsoft Academic Search

Valves are used in piping systems to control flow rates and to regulate pressures. Whenever a large pressure drop occurs across a valve, the possibility of cavitation exists. A system can be subject to noise, vibration, and erosion damage when operating in a cavitating flow range. To quantify these effects in terms of different stages of cavitation, this paper presents

William J. Rahmeyer

1981-01-01

216

Valve for abrasive material  

SciTech Connect

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

Gardner, H.S.

1982-08-31

217

Endobronchial valve migration.  

PubMed

Endobronchial valves are increasingly used as a treatment modality as a less invasive alternative to lung volume reduction surgery in patients with severe emphysema. Endobronchial valves have also been used to treat patients with persistent pulmonary air leaks and those with bronchopleural fistulae. We report a case of a 61-year-old male with severe bullous emphysema. Following video-assisted thoracoscopic surgery and giant bullectomy, he had a persistent air leak. We inserted two endobronchial valves (in the lingular lobe and the anterior segment of the upper lobe) and the air leak ceased immediately. However, over the subsequent 5 months following the insertion of the endobronchial valves, the patient suffered recurrent chest infections and the endobronchial valves were found to have migrated to the orifice of the basal segment of the left lower lobe and the orifice of the basal segments of the right lower lobe. PMID:21435897

Jenkins, Melanie; Vaughan, Paul; Place, David; Kornaszewska, Malgorzata

2011-03-23

218

Artificial neural networks in computer-assisted classification of heart sounds in patients with porcine bioprosthetic valves  

Microsoft Academic Search

The paper describes the design, training and testing of a three-layer feedforward back-propagation neural network for the\\u000a classification of bioprosthetic valve closure sounds. Forty-seven patients with a porcine bioprosthetic valve inserted in\\u000a the aortic position were involved in the study. Twenty-four of them had a normal bioprosthetic valve, and the other 23 had\\u000a a degenerated valve. Five features extracted from

Z. Guo; L.-G. Durand; H. C. Lee; L. Allard; M.-C. Grenier; P. D. Stein

1994-01-01

219

Durability of the pericardial valve.  

PubMed

The fate of 1001 pericardial xenograft valves was analysed during a maximum follow-up period of 13 years. Two basic types of pericardial valves have been implanted. Between 1971 and 1975, 213 patients received 'hospital made' valves (single replacement). Between 1976 and 1983, 601 patients received 788 pericardial valves manufactured by Shiley Inc. (474 Standard and 314 Low profile valves) for both single and multiple replacement. There were 27 instances of valve dysfunction between 13 and 92 months after operation, 20 with 'hospital made' and 7 with Shiley valves. The actuarial freedom from valve failure at 8 years is 94.0 +/- 4.6% for aortic and 98.8 +/- 1.2% for mitral replacement in patients with Shiley valves. In patients with 'hospital made' valves the actuarial freedom from valve failure at 12 years of follow-up is 86.7 +/- 7.6% for aortic and 84.7 +/- 14.1% for mitral replacement. The linearised rate of valve dysfunction was 0.31% per annum for Shiley valves and 1.27% per annum for 'hospital made' valves. This analysis demonstrates that the pericardial xenograft has a low risk of valve failure and a predictable behaviour over a period of 13 years. The Shiley made valves have shown improved durability when compared with the 'hospital made' valves. PMID:6519096

Ionescu, M I; Tandon, A P; Chidambaram, M; Yakirevich, V S; Silverton, N P

1984-10-01

220

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

221

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.

Luo, Huai

2012-01-01

222

Single and Multiple Valve Surgery in Native Valve Infective Endocarditis  

PubMed Central

Background Surgical treatment of infective endocarditis (IE) remains a challenge, especially in cases of multiple valve surgery. We evaluated the clinical outcomes of native valve IE and compared the outcomes of single valve surgery with those of multiple valve surgery. Materials and Methods From 1997 to 2011, 90 patients underwent surgery for native valve IE; 67 patients with single valve surgery (single valve group) and 23 patients with multiple valve surgery (multiple valve group). The mean follow-up duration was 73.1±47.4 months. Results The surgical mortality in the total cohort was 4.4%. The overall survival (p=0.913) and valve-related event-free survival (p=0.204) did not differ between the two groups. The independent predictor of postoperative complications was New York Heart Association class (p=0.001). Multiple valve surgery was not a significant predictor of surgical mortality (p=0.225) or late mortality (p=0.936). Uncontrolled infection, urgent or emergency surgery, and postoperative complications were identified as independent predictors of valve-related morbidity, excluding multiple valve surgery (p=0.072). Conclusion In native valve IE, multiple valve surgery as a factor was not an independent predictor of mortality and morbidity. The number of surgically corrected valves in native IE seems to be unrelated to perioperative and long-term outcomes.

Kim, Tae Sik; Oh, Sam Sae; Kim, Jae Hyun; Yie, Gil Soo; Han, Jung Wook; Chae, Min Cheol

2013-01-01

223

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

Bjork, Viking Olov

1970-01-01

224

Valve timing and valve lift control mechanism for engines  

Microsoft Academic Search

A new type engine valve control system has been presented, in which both the valve lift and valve timing are controlled directly by electric motors. A mechanism of the valve timing control system is made of planetary gears. The outer gear is the timing pulley which has a timing belt driven by the crankshaft of an engine. Two planetary gears

Kosuke Nagaya; Hiroyuki Kobayashi; Kazuya Koike

2006-01-01

225

Dual hydraulic safety valve  

SciTech Connect

This patent describes a subsurface well safety valve for controlling the fluid flow through a well conduit and including a housing having a bore and a valve closure member moving between open and closed positions for controlling the fluid flow through the bore, a tubular member telescopically moving in the housing for controlling the movement of the valve closure member. The improvement in fluid actuating means for actuating the valve closure member comprising, a first piston and cylinder assembly in the housing adapted to be connected to a hydraulic control line, the first assembly connected to the tubular member, a second piston and cylinder assembly in the housing adapted to be connected to a hydraulic control line, the second assembly disconnected from the tubular member, and means for disconnecting the first assembly from the tubular member and connecting the second assembly to the tubular member. The method of operating a subsurface well safety valve for controlling the fluid flow through a well conduit in which the valve includes a housing having a bore and a valve closure member moving between open and closed positions for controlling the fluid flow through the bore.

Leismer, D.D.; Blizzard, W.A. Jr.

1989-06-13

226

Valve body for oilfield applications  

SciTech Connect

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

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

1992-01-21

227

High Temperature Ultrahigh Vacuum Valves.  

National Technical Information Service (NTIS)

All-metal valves heatable up to 300 to 400 C in closed and open position were developed for handling aggressive gases such as UF6 in high vacuum technology. Sealing aspects of valves with large nominal width, such as transfer valve NW 150 and corner valve...

W. Baechler G. Jokisch H. P. Kabelitz K. Teutenberg

1976-01-01

228

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

229

Exhaust gas recirculation valve assembly  

SciTech Connect

This paper describes an exhaust gas recirculation valve assembly. It comprises: a base having an exhaust gas chamber through which exhaust gas passes; a pintle valve assembly having a valve member disposed within the exhaust gas chamber and a valve stem extending outwardly of the chamber through an opening therein; an actuator, maintained in a fixed relationship to the base, coupling means, extending between the valve stem and the armature and configured to allow lateral movement of the valve stem relative to the armature to compensate for misalignment of the actuator relative to the base thereby preventing the misalignment from affecting the reciprocal operation of the pintle valve assembly relative to the base.

Grey, T.J.; Braun, C.N.; Palmer, D.O.

1991-06-04

230

AcidBase Variables During Incremental Exercise in Sprint-Trained Horses Fed a High-Fat Diet  

Microsoft Academic Search

Seven Arabian horses performed a standard incremental exercise test on a high-speed treadmill at 6% slope then were randomly assigned to two diets, a control diet of ground hay and concen- trates and a similar diet with 10% added fat (by weight). Horses were sprint-trained 4 dwk, and two additional exercise tests were performed at 5-wk intervals. Heart rates and

L. E. Taylor; P. L. Ferrante; D. S. Kronfeld; T. N. Meacham

231

Vibrations due to a test train at variable speeds in a deep bored tunnel embedded in London clay  

NASA Astrophysics Data System (ADS)

This paper reports on the results of in situ vibration measurements that have been performed within the frame of the CONVURT project at a site in Regent's Park on the Bakerloo line of London Underground during 35 passages of a test train at a speed between 20 and 50 km/h. Vibration measurements have been performed on the axle boxes of the test train, on the rails, on the tunnel invert and tunnel wall, and in the free field, both at the surface and at a depth of 15 m. Measurements have also been made on floors and columns of two buildings in a row of Regency houses at a distance of 70 m from the tunnel. Prior to these vibration measurements, the dynamic soil characteristics have been determined by in situ and laboratory testing. Rail and wheel roughness have been measured and the track characteristics have been determined by rail receptance and wave decay measurements. Time histories and one-third octave band RMS spectra of the measured velocities are discussed and the variation of the peak particle velocity and the frequency content as a function of the train speed and the distance to the tunnel are elaborated.

Degrande, G.; Schevenels, M.; Chatterjee, P.; van de Velde, W.; Hölscher, P.; Hopman, V.; Wang, A.; Dadkah, N.

2006-06-01

232

Development of prosthetic aortic heart valves  

Microsoft Academic Search

Investigates various new prototypes of aortic valves. The fabricated valve prototypes were then tested by various hydrodynamic and hemocompatibility tests. The various prototype values designed and fabricated were: (1) a bileaflet valve, (2) a conical poppet valve, (3) a disc poppet valve, and (4) a fluidic nozzle valve. These valves were tested for percentage regurgitation across them, for pressure drop

S. A. Ulman; B. D. Vyas; R. R. Puniyani

1995-01-01

233

Assessing Technical Training Needs.  

ERIC Educational Resources Information Center

Describes the results of a joint project of St. Cloud State University (Minnesota) and DeZURIK Corporation (a manufacturer and distributor of industrial valves) which developed and implemented a technical training needs questionnaire for use with the company's employees. Student involvement in the process is noted. (MBR)

Schwaller, Anthony E.; Slipy, Dave

1985-01-01

234

Bicuspid Aortic Valve.  

National Technical Information Service (NTIS)

Bicuspid aortic valve is a common congenital heart defect, often diagnosed incidentally or as a consequence of an associated condition. Patients with this anomaly are at increased risk for a variety of cardiovascular complications and require surveillance...

J. R. Cooney V. B. Ho

2006-01-01

235

Get valves repaired properly  

SciTech Connect

Valve users are generally unanimous in their dissatisfaction with valve reconditioning programs. Their dissatisfaction is expressed in three complaints: poor service, poor quality and total costs which often approach or exceed valve replacement costs. These complaints are clearly legitimate, and the providers of valve reconditioning services must shoulder a significant part of the blame. However, scrutiny of the reasons for dissatisfaction reveals that some portion of the blame must also be borne by the users. Since many of the practices that cause the user's complaints are rooted in the early development of this market, a review of that development is helpful in understanding how these problems arose, and leads to a better understanding of the steps necessary for improvement.

Robert, R.W.

1988-02-01

236

Mitral Valve Prolapse  

MedlinePLUS

... one or both flaps collapse backward into the left atrium. In some cases, the prolapsed valve lets a ... ventricle of the heart is enlarged • The heart function gets worse MVP very rarely becomes a highly ...

237

THERMALLY OPERATED VAPOR VALVE  

DOEpatents

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

Dorward, J.G. Jr.

1959-02-10

238

Valve Sizing and Selection  

NSDL National Science Digital Library

This website, from the Chemical Engineers' Resource Page, contains an article on how to properly size and select a control valve used in the process control industry. It also includes a list of additional resources related to process control.

2009-09-04

239

Mitral Valve Repair Surgery  

MedlinePLUS Videos and Cool Tools

... with the annular dilation, I think, is the principle reason this valve is leaking. So what we’ ... posterior annulus and by virtue of gauging the distance between these sutures, one can eventually, you see, ...

240

Downhole flapper valve  

SciTech Connect

A flapper valve has integral, oppositely projecting hinge pins mounted in a recess provided between two abutting tubular housing members. The flapper valve is of cylindrical segment configuration so as to maximize the opening within a conduit in which it is mounted when the flapper valve is pivoted to its open position. The spring bias urging the flapper valve to the closed position is provided by helical springs mounted in surrounding relationship to the axis of the conduit and in an annular recess provided between two abutting tubular housing members. The bottom surface of the actuating sleeve for the flapper is contoured so as to exert a minimum unbalanced torque on the flapper valve during opening with the mechanical opening force being balanced by an opposing force exerted by fluid pressure. Such construction permits a substantial reduction in the size of the hinge pins and the space required to mount the pins and the helical springs, thus reducing the radial proportions of the flapper valve assemblage to increase the open bore diameter.

Fineberg, D. H.

1985-07-30

241

The Relationship of Learning Style, Aptitude and Instructional Program Variables to Achievement in the Military Training Environment.  

ERIC Educational Resources Information Center

The purpose of this study was to determine how 16 Navy (self-paced) and 18 Marine Corps (group-paced) Aviation Storekeeper Schools students would perform on the same test, assessing mastery of an identical topic related to the selected variables of learning styles and Armed Service Vocational Aptitude Battery (ASVAB) test scores. No significant…

Enochs, J. R.; And Others

242

Rod operated rotary well valve  

SciTech Connect

A well valve for use in a tubing string in a well bore of an oil or gas well to isolate a lower portion of the well bore below a packer including a body having a longitudinal bore therethrough connectible in a well tubing string, a lower annular valve seat supported in the body for limited sliding movement, fluid seal means between the lower valve seat and the body, an upper annular valve seat supported in longitudinal spaced relation from the lower valve seat within the body, a ball valve member supported for rotation between opened and closed positions between the valve seats, pivot members secured with the ball valve member for rotating the valve member, and a longitudinally movable operator member coupled with the pivot members for moving the pivot members longitudinally while permitting the members to traverse an arcuate path as the ball valve member rotates between open and closed positions. The valve seals both upwardly and downwardly and is opened and closed without longitudinal travel of either seat or the ball valve member. The valve is useful in various types of well installations for production and testing procedures and is operable by manipulation of operator means coupled into the valve from an upper tubing string.

Fredd, J.V.

1980-10-28

243

SOFTWARE ENABLED VARIABLE DISPLACEMENT PUMPS - EXPERIMENTAL STUDIES  

Microsoft Academic Search

The majority of hydraulic systems are controlled using a me- tering valve or the use of variable displacement pumps. Metering valve control is compact and has a high control bandwidth, but it is energy inefficient due to throttling losses. Variable d isplace- ment pumps are far more efficient as the pump only produces the required flow, but comes with the

Michael B. Rannow; Haink C. Tu; Perry Y. Li; Thomas R. Chase

2006-01-01

244

Flight Simulator: Comparison of Resolution Thresholds for Two Light Valve Video Projectors.  

National Technical Information Service (NTIS)

The Air Force Human Resources Laboratory/Operations Training Division is developing a visual system for advanced tactical air combat simulators. As part of this work, two light valve video projectors were evaluated on their ability to display small, high-...

P. M. Crane J. P. Gerlicher H. H. Bell

1986-01-01

245

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

246

Bottom hole sampler and safety valve and valve therefor  

SciTech Connect

A ball valve is described for use in downhole tools such as bottom hole samplers and safety valves comprising a tubular housing, a ball having an opening therethrough, a valve seat engaging the ball, means mounting the ball for rotation around an axis transverse the longitudinal axis of the housing, a valve operator connected to the ball to rotate the ball to an open position with its opening parallel to the longitudinal axis of the housing when the operator is moved in one direction and to rotate the ball to a closed position with the opening extending transverse the longitudinal axis of the housing when the operator is moved in the opposite direction, piston means connected to the valve operator responsive to fluid pressure to move the valve operator in one direction, and reset means operable through the open end of the housing for moving the valve operator to return the valve to the open position.

Meek, D.E.

1986-09-09

247

39. TAINTER GATE VALVES, OPERATING MACHINERY, AND VALVE ASSEMBLED AUXILIARY ...  

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

39. TAINTER GATE VALVES, OPERATING MACHINERY, AND VALVE ASSEMBLED AUXILIARY LOCK. January 1932 - Mississippi River 9-Foot Channel Project, Lock & Dam No. 15, Upper Mississipi River (Arsenal Island), Rock Island, Rock Island County, IL

248

Sizing safety valve vent pipes for saturated steam  

SciTech Connect

A generalized procedure based on pressure and entropy as independent variables is used to calculate choked flow conditions at the valve orifice, valve pipe outlet and vent pipe outlet. At the third location, the results are independent of whether flow in the vent pipe is supersonic or subsonic. An integral method is used to calculate the vent pipe length required to choke the flow. 16 refs.

Brandmaier, H.E.

1982-01-01

249

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

250

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

251

Fast closing valve  

SciTech Connect

A valve is provided for protecting the high vacuum of a particle accelerator 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 which can rotate between a first position wherein a bore in the member is aligned with the beam pipe, and a second position out of line with the pipe. A seal member 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 fixed to it and which is rotated by the discharge of a capacitor bank through coils located adjacent to the arm.

Hanson, C.L.

1984-01-10

252

[Technologies for cardiac valve prostheses].  

PubMed

To show the technological development of cardiac valve prostheses, a historical review of both mechanical and biological valve prostheses and a current overview of modern cardiac valve devices are provided. Scince the 1st implantation of Starr-Edwards ball valve in 1960, both mechanical and biological valve prostheses have advanced. The valve design, the material of the leaflet and the hausing of mechanical prostheses have improved. Currently, the majority of the mechanical prostheses are bileaflet tilting disc valves made of pyrolytic carbon, which is antithromboembolic. However, anticoagulation therapy with warfarin is still required. As for the bioprostheses, although the fixation and anti-mineralization methods of the tissues improved, the durability of these valves is still limited. For the material of the current biological valves, the porcine aortic valve or bovine pericardium are used. The tissues are fixed by non-pressure or low-pressure method in glutaraldehyde solution. A stented and non-stented valves are available. Epoch-making events in this field are the implantation of new bioprosthetic valves using tissue engineering methods and the development of the transcatheter valve replacement therapies. PMID:20715694

Nakano, Kiyoharu

2009-07-01

253

Flow-valve: embedding a safety-valve in RED  

Microsoft Academic Search

In this paper, we present the flow-valve, a safety-valve mechanism for RED (random early detection) to protect the network from misbehaving or overpumping flows and to promote end-to-end congestion control. The flow-valve can be regarded as an implementation of the concept known as a “RED penalty-box” but our focus is to protect router resources in times of congestion. The flow-valve

Kenjiro Cho

1999-01-01

254

81. View of 41 valve house (right) and 42 valve ...  

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

81. View of 4-1 valve house (right) and 4-2 valve house (left); in the foreground is penstock which extends from Penstock No. 1 to the 4-1 valve house; looking south. Photo by Jet Lowe, HAER, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

255

83. Interior of 42 valve house; the motor and valve ...  

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

83. Interior of 4-2 valve house; the motor and valve mechanism is identical to that in the 4-1 valve house. Photo by Jet Lowe, HAER, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

256

Super seal valve with mechanically retained seal  

Microsoft Academic Search

This patent describes an improved valve assembly used in a well cementing tool in a well cementing operation or the like, the valve assembly comprising: an annular valve body housing retained within the cementing tool or the like, the annular valve body housing comprising: a valve seat portion having a bore therethrough; and a valve spring retainer portion secured to

M. G. Baldridge; B. L. Sullaway

1986-01-01

257

Reoperations after tricuspid valve repair  

Microsoft Academic Search

Objective: The objective was to analyze the short- and long-term results of patients with previous tricuspid valve repair who had valve dysfunction and required cardiac reoperations. Methods: Between 1976 and 2002, 74 patients with a mean age of 53.8 12.2 years underwent valve reoperations for dysfunction of previous tricuspid valve repair. Mitral and tricuspid lesions were diagnosed in 40 patients

José M. Bernal; Dieter Morales; Carmen Revuelta; Javier Llorca; Jesús Gutiérrez-Morlote; José M. Revuelta

2010-01-01

258

Ball valve safety screen  

SciTech Connect

A device for preventing unwanted objects from entering the ball assembly of a float collar or float shoe and otherwise damaging or plugging the valve mechanism therein is disclosed. The device comprises a screen constructed of expanded metal and rigidly affixed to the interior of the float collar or float shoe above the ball valve assembly. The screen portion is either mounted to the interior surface of the float collar sleeve by an annular structural member or mounted to a structural band which is partially embedded in the concrete portion of the float collar or casing guide shoe.

Bolding, B.H.

1981-09-01

259

Pressure Relief Valve  

NASA Astrophysics Data System (ADS)

"Sputtering" is the process of applying film-like metal coatings onto a surface by bombarding the coating material with electrocharged ions. This causes the material to disintegrate and relocate on the substrate an atom layer at a time. The process allows a variety of coating materials to be deposited on various surfaces. Deposition Technology, Inc. (DTI) uses "sputtering" for window films, packaging materials, etc. Valves installed on two vacuum chambers which are part of DTI's system, were developed by Lewis Research Center and detailed in Tech Briefs. The valve protects the environment and frees the operator from monitoring the chamber venting.

1985-01-01

260

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

261

Liquid crystal light valve projectors for simulation applications  

Microsoft Academic Search

The desirability of realistically simulating the real world in the training environment leads to requirements for high resolution, high brightness, color, uniformity of these parameters across the field of view, and real-time operation. The liquid crystal light valve (LCLV) is a unique development which has the potential for meeting the stringent demands of many simulation applications. A description of LCLV

P. C. Baron; D. E. Sprotbery

1978-01-01

262

Valve selection handbook. Third edition  

Microsoft Academic Search

This book covers the fundamentals of value construction and application, and analyzes the different hazards and requirements of all types of industrial fluid flow situations. This book expands the coverage of pressure relief valves and rupture discs. It includes a new section on damping valve chatter, which is a serious problem in installations such as atomic power plants where valve

Zappe

1991-01-01

263

High temperature subsurface safety valve  

Microsoft Academic Search

This patent describes in a subsurface well safety valve for controlling the fluid flow through a well conduit and including a housing having a bore and a valve closure member moving between open and closed positions for controlling the fluid flow through the bore. A flow tube telescopically moves in the housing for controlling the movement of the valve closure

1987-01-01

264

Prosthetic Heart Valve and Pregnancy  

Microsoft Academic Search

We studied 59 pregnancies in 48 female carriers of prosthetic heart valves. In 44 pregnancies the mother had a metal valve mostly with coumarin therapy and in 15 a bioprosthesis usually without hematologic treatment. In the patients with metal prostheses we had the following maternal complications: 1 maternal death, 3 valve thromboses, 2 heart failures and puerperal hemorrhage. There was

R. Matorras; J. A. Reque; J. A. Usandizaga; J. A. Minguez; J. L. Larrea; L. Núñez

1985-01-01

265

The cardiac valve interstitial cell  

Microsoft Academic Search

Cardiac valve interstitial cells (ICs) are a heterogeneous and dynamic population of specific cell types that have many unique characteristics. They are responsible for maintaining the extracellular scaffold that provides the mechanical characteristics vital for sustaining the unique dynamic behaviour of the valve. A number of cellular phenotypes can be distinguished: some are sparsely arranged throughout the valve leaflets, whilst

Patricia M Taylor; Puspa Batten; Nigel J Brand; Penny S Thomas; Magdi H Yacoub

2003-01-01

266

Well safety and kill valve  

SciTech Connect

A valve device is described for use in tubing above a packer set in casing above a well formation comprising: (a) a housing connectable in well tubing and having a longitudinal flow passage therethrough and a flow passage through the housing wall intersecting the longitudinal flow passage; (b) lower ball valve means controlling flow through the longitudinal flow passage; (c) upper sleeve valve means controlling flow through the housing wall flow passages between the valve device exterior and the longitudinal flow passage. The valve means is cooperable such that when the upper valve means is in closed position, the lower valve means is in open position, and when the upper valve means is in open position, the lower valve means is in closed position; (d) locking means for holding the valve means at one position and releasing the valve means for movement to another position; (e) pressure responsive means for releasing the locking means; and (f) operator means for operating the valve means between positions including an operator tube having a shoulder thereon, mounted for longitudinal movement in the housing, an internal shoulder in the housing and a spring disposed around the operator tube between the housing and operator tube shoulders, biasing the operator tube upwardly.

Deaton, T.M.

1986-12-30

267

The relation between anthropometric and physiological variables and bat velocity of high-school baseball players before and after 12 weeks of training.  

PubMed

The purpose of this article was to investigate the relation between anthropometric and physiological variables to linear bat swing velocity (BV) of 2 groups of high-school baseball players before and after completing a 12-week periodized resistance exercise program. Participants were randomly assigned to 1 of 2 training groups using a stratified sampling technique. Group 1 (n = 24) and group 2 (n = 25) both performed a stepwise periodized resistance exercise program and took 100 swings a day, 3 d·wk-1, for 12 weeks with their normal game bat. Group 2 performed additional rotational and full-body medicine ball exercises 3 d·wk-1 for 12 weeks. Fourteen variables were measured or calculated before and after 12 weeks of training. Anthropometric and physiological variables tested were height, body mass, percent body fat, lean body mass (LBM), dominant torso rotational strength (DTRS) and nondominant torso rotational strength (NDTRS), sequential hip-torso-arm rotational strength measured by a medicine ball hitter's throw (MBHT), estimated 1 repetition maximum parallel squat (PS) and bench press (BP), vertical jump (VJ), estimated peak power, angular hip velocity (AHV), and angular shoulder velocity (ASV). The baseball-specific skill of linear BV was also measured. Statistical analysis indicated a significant moderately high positive relationship (p ? 0.05) between prelinear BV and pre-NDTRS for group 1, pre-LBM, DTRS, NDTRS, peak power, and ASV for group 2; moderate positive relationship between prelinear BV and preheight, LBM, DTRS, peak power, BP, PS, and ASV for group 1, preheight, body mass, MBHT, BP, and PS for group 2. Significantly high positive relationships were indicated between postlinear BV and post-NDTRS for group 1, post-DTRS and NDTRS for group 2; moderately high positive relationships between postlinear BV and post-LBM, DTRS, peak power, BP, and PS for group 1, postheight, LBM, VJ, peak power for group 2; moderate positive relationships between postlinear BV and postheight, body mass, MBHT, and VJ for group 1, postbody mass, MBHT, BP, PS, and ASV for group 2. Significantly low positive relationships were indicated between prelinear BV and prebody mass, MBHT, and VJ for group 1, pre-VJ and AHV for group 2; postlinear BV and post-AHV for group 2. These data show that significant relationships do exist between height, body mass, LBM, rotational power, rotational strength, lower body power, upper and lower body strength, AHV, and ASV to linear BV of high-school baseball players. Strength coaches may want to consider using this information when designing a resistance training program for high-school baseball players. Those recruiting or scouting baseball players may want to use this information to further develop ways of identifying talented players. However, one should be cautious when interpreting this information when designing strength training programs for high-school baseball players to increase linear BV. PMID:20881505

Szymanski, David J; Szymanski, Jessica M; Schade, Ryan L; Bradford, T Jason; McIntyre, Joseph S; DeRenne, Coop; Madsen, Nels H

2010-11-01

268

The natural history of aortic valve disease after mitral valve surgery  

Microsoft Academic Search

OBJECTIVESThe present study evaluates the long-term course of aortic valve disease and the need for aortic valve surgery in patients with rheumatic mitral valve disease who underwent mitral valve surgery.BACKGROUNDLittle is known about the natural history of aortic valve disease in patients undergoing mitral valve surgery for rheumatic mitral valve disease. In addition there is no firm policy regarding the

Mordehay Vaturi; Avital Porter; Yehuda Adler; Yaron Shapira; Gideon Sahar; Bernardo Vidne; Alex Sagie

1999-01-01

269

Emergency transseptal transcatheter mitral valve-in-valve implantation.  

PubMed

Aims: We report a case of emergency transcatheter heart valve implantation in a failing mitral bioprosthesis via a transseptal access complicated by the atrial migration of a prosthesis. Methods and results: A 42-year-old woman was referred for stenotic failure of a mitral bioprosthesis. A transapical valve-in-valve implantation was initially planned. However, due to sudden haemodynamic deterioration, an emergency transseptal implantation via a femoral venous access was undertaken. Following cardiac arrest, the procedure was performed with extracorporeal membrane oxygenation (ECMO), and was complicated by the migration of a valve, which was left moving freely in the left atrium. A second valve was successfully implanted in the mitral bioprosthesis. Following initial clinical recovery, there was a sudden recurrence of heart failure due to entrapment of the migrated valve in the implanted valve in a "reverse position", which was dislodged percutaneously in an emergency procedure. The valve later migrated into the left atrial appendage. Immediate outcome was uneventful, but the patient suddenly died six months later. Conclusions: Transseptal transcatheter mitral valve-in-valve implantation is feasible, even in an emergency setting with ECMO. Valve migration in the left atrium may occur and lead to late entrapment in a "reverse position", with significant haemodynamic consequences. PMID:24058080

Fassa, Amir-Ali; Himbert, Dominique; Brochet, Eric; Alkhoder, Soleiman; Al-Attar, Nawwar; Brun, Pierre-Yves; Wolff, Michel; Nataf, Patrick; Vahanian, Alec

2013-09-22

270

Flow metering valve  

Microsoft Academic Search

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

Blaedel

1983-01-01

271

Flow metering valve  

Microsoft Academic Search

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

Blaedel

1985-01-01

272

Pressure Sensitive Regulation Valve.  

National Technical Information Service (NTIS)

The patent application relates to a pressure sensitive regulating valve formed of a spring mounted within a conduit in which fluid flow is to be regulated. The fluid flow is regulated by the pressure responsive expansion and contraction of the axially def...

E. A. Gallo

1975-01-01

273

Safety valves for photosynthesis  

Microsoft Academic Search

Recent studies have provided new insights into the ways that plants may dissipate excess photons and electrons, thereby protecting the photosynthetic apparatus against light-induced damage. These ‘safety valves’ include nonphotochemical mechanisms for quenching excited chlorophylls, as well as alternative electron acceptors such as oxygen.

Krishna K Niyogi

2000-01-01

274

A symmetric safety valve  

Microsoft Academic Search

How to set policy in the presence of uncertainty has been central in debates over climate policy. Concern about costs has motivated the proposal for a cap-and-trade program for carbon dioxide, with a “safety valve” that would mitigate against spikes in the cost of emission reductions by introducing additional emission allowances into the market when marginal costs rise above the

Dallas Burtraw; Karen Palmer; Danny Kahn

2010-01-01

275

TUBE SHEARING VALVE  

DOEpatents

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

Wilner, L.B.

1960-05-24

276

Robotic mitral valve surgery  

Microsoft Academic Search

Currently, cardiac surgery is an evolving field. Not only has there been a technological explosion, but there also is a strong interest in minimally invasive operations. Mitral valve surgery can now be performed with the use of sophisticated robotic systems through small incisions. The patient of today and the future will demand minimally invasive operations. Initial clinical experience with robotic

Alan P. Kypson; W. Randolph Chitwood

2004-01-01

277

Minimally Invasive Valve Operations  

Microsoft Academic Search

Background. To reduce the morbidity from valvular heart operations, a right parasternal approach was introduced. We report our initial experience with the procedure.Methods. From January 1996 through July 1996, 115 patients underwent primary isolated valve procedures. One hundred (85%) patients underwent the operation through a right parasternal incision.Results. There was one hospital death secondary to a stroke on the fifth

Delos M Cosgrove; Joseph F Sabik; José L Navia

1998-01-01

278

Distortion of the CoreValve during transcatheter aortic valve-in-valve implantation due to valve dislocation.  

PubMed

Nowadays transcatheter aortic valve implantation (TAVI) is an accepted alternative to surgical aortic valve replacement for high-risk patients (pts). Successful TAVI procedures for failed aortic surgical bioprosthesis (TAV-in-SAV) have already been reported. In the presented two cases of TAV-in-SAV implantation a strut distortion of the stent was revealed on angiographic imaging and confirmed on control CT scan. In both procedures, a dislocation of the medtronic core valve (MCV) prosthesis during implantation led to valve retrieval, with a necessity of reloading it in the 18F introducer before subsequent implantation of the same valve in correct position. PMID:23933060

Souteyrand, Geraud; Wilczek, Krzysztof; Innorta, Andrea; Camilleri, Lionel; Chodor, Piotr; Lusson, Jean-René; Motreff, Pascal; Laborde, Jean-Claude; Chabrot, Pascal; Durel, Nicolas

2013-08-09

279

Valve selection handbook. Third edition  

SciTech Connect

This book covers the fundamentals of value construction and application, and analyzes the different hazards and requirements of all types of industrial fluid flow situations. This book expands the coverage of pressure relief valves and rupture discs. It includes a new section on damping valve chatter, which is a serious problem in installations such as atomic power plants where valve chatter could have catastrophic consequences to the safety of the plant. There is also new information on performance of spring-loaded pressure relief valves and a closer examination of valve selection with respect to rupture discs and explosion venting.

Zappe, R.W. (ICI Australia Operations Pty. Ltd. (AU))

1991-01-01

280

Cortisol release, heart rate and heart rate variability in the horse and its rider: Different responses to training and performance.  

PubMed

Although some information exists on the stress response of horses in equestrian sports, the horse-rider team is much less well understood. In this study, salivary cortisol concentrations, heart rate (HR) and heart rate variability (HRV), SDRR (standard deviation of beat-to-beat interval) and RMSSD (root mean square of successive beat-to-beat intervals) were analysed in horses and their riders (n=6 each) at a public performance and an identical rehearsal that was not open to the public. Cortisol concentrations increased in both horses and riders (P<0.001) but did not differ between performance and rehearsal. HR in horses and riders increased during the rehearsal and the public performance (P<0.001) but the increase in HR was more pronounced (P<0.01) in riders than in their horses during the public performance (from 91±10 to 150±15beats/min) compared to the rehearsal (from 94±10 to 118±12beats/min). The SDRR decreased significantly during the equestrian tasks in riders (P<0.001), but not in their horses. The RMSSD decreased in horses and riders (P<0.001) during rehearsal and performance, indicating a decrease in parasympathetic tone. The decrease in RMSSD in the riders was more pronounced (P<0.05) during the performance (from 32.6±6.6 to 3.8±0.3ms) than during the rehearsal (from 27.5±4.2 to 6.6±0.6ms). The study has shown that the presence of spectators caused more pronounced changes in cardiac activity in the riders than it did in their horses. PMID:23380228

von Lewinski, Mareike; Biau, Sophie; Erber, Regina; Ille, Natascha; Aurich, Jörg; Faure, Jean-Michel; Möstl, Erich; Aurich, Christine

2013-02-04

281

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

282

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.

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

2013-01-01

283

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

284

Micro-valve pump light valve display  

DOEpatents

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

Lee, Yee-Chun.

1991-01-15

285

Micro-valve pump light valve display  

DOEpatents

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

Lee, Yee-Chun

1991-01-15

286

Transcatheter aortic "valve-in-valve" for degenerated bioprostheses: Choosing the right TAVI valve  

PubMed Central

Bioprosthetic aortic valve replacement is the treatment of choice for patients over 65 years of age suffering from aortic valve disease, and for younger patients with contraindications to long-lasting anticoagulation. Despite several technical improvements to reduce the risk of structural valve degeneration (SVD), the risk of SVD still exists, in particular for hemodialysis patients and patients under 60 years of age at surgery. Redo open heart surgery is the treatment of choice in case of valve degeneration, but caries a higher surgical risk when elderly patients with comorbidities are concerned. In the last 5 years, transcatheter aortic “valve-in-valve” procedures represent a valid alternative to standard redo surgery in selected patients. Valve-in-valve procedures represent a less invasive approach in high-risk patients and the published results are very encouraging. Technical success rates of 100% have been reported, as have the absence of paravalvular leaks, acceptable trans-valvular gradients (depending on the size of the original bioprosthesis), and low complication rates. The current article focuses on choosing the correct transcutaneous valve to match the patient’s existing bioprosthesis for valve-in-valve procedures.

2012-01-01

287

Cryogenic leak testing of tube fittings\\/valves  

Microsoft Academic Search

A high pressure and variable temperature cryogenic leak testing system was conceived and designed in order to conduct leakage testing of pipe fittings\\/valves in liquid hydrogen supply lines of the Space Shuttle. The system can create a continuous testing environment of variable temperature, 5.5 to about 300 K, and variable pressure, 0.01 to about 70 x 10 exp 5 Pa,

L. X. Jia; D. Moslemian; W. L. Chow

1992-01-01

288

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

289

Valving apparatus for downhole tools  

SciTech Connect

A valving apparatus supplies increased fluid pressure to a downhole tool having fluid pressure actuated expandable packing elements. The valving apparatus includes upper and lower annular sealing surfaces and a shuttle valve which, in its normal spring surfaces and a shuttle valve which, in its normal spring biased position, engages the upper sealing surface and maintains a connection between the bore of the downhole tool and the casing annulus, thereby equalizing pressure therebetween. When pressure in the work string is increased through dropping of a ball on a seat contained in the valving apparatus, the increased fluid pressure is bypassed around the ball valve to impinge upon a piston surface incorporated on the shuttle valve, moving the shuttle valve downwardly into sealing engagement with the lower annular sealing surface and thus transmitting increased pressure to the downhole tool. Upon release of the increased pressure, The shuttle valve returns to its normal position in sealing engagement with the upper annular sealing surface and opens the fluid flow connection between the interconnected bores of the valving apparatus and the downhole tool and the casing annulus.

Speller, D.J.

1984-12-04

290

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

Code of Federal Regulations, 2011 CFR

... 2011-10-01 false Inhalation and exhalation valves; check valves; minimum requirements. 84.137 Section 84...Respirators § 84.137 Inhalation and exhalation valves; check valves; minimum requirements. (a)...

2011-10-01

291

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

Code of Federal Regulations, 2012 CFR

... 2012-10-01 false Inhalation and exhalation valves; check valves; minimum requirements. 84.137 Section 84...Respirators § 84.137 Inhalation and exhalation valves; check valves; minimum requirements. (a)...

2012-10-01

292

Valve-preserving surgery on the bicuspid aortic valve.  

PubMed

Valve repair has emerged as an important intervention for the management of bicuspid aortic valve disease. This systematic review aims to assess the safety, efficacy and durability of bicuspid aortic valve repair. Initial searches yielded 682 abstracts, reduced by de-duplication to 370, of which 56 full papers were accessed and 30 met the inclusion criteria. Overall, 163 unique outcomes for bicuspid aortic valve-preserving surgery were reported on 280 occasions. Bicuspid aortic valve-preserving surgery exhibited low operative mortality (0.0-5.2%), excellent 5-year survival (82-100%) and 43-100% 5-year freedom from reoperation. Bicuspid aortic valve repair is safe and efficacious, but concerns regarding its durability necessitate further standardized outcome assessments. PMID:23293321

Vohra, Hunaid A; Whistance, Robert N; De Kerchove, Laurent; Punjabi, Prakash; El Khoury, Gebrine

2013-01-04

293

Prosthetic valve endocarditis.  

PubMed Central

During 1965 to 1982, 32 episodes of infective endocarditis on prosthetic valves in 30 patients were treated at this hospital. In early endocarditis (presenting within four months of operation) staphylococci were the organisms most commonly responsible. Early endocarditis appears to be declining in incidence and is largely preventable; sternal sepsis was the main predisposing factor, requiring urgent and effective treatment. Streptococci were the most common organisms in late onset disease, but as with natural valve endocarditis a wide range or organisms was responsible. All but one of the patients with early onset disease were treated conservatively, but mortality was high; prompt surgical replacement of infected prostheses is probably indicated in such patients. Medical management was effective in most patients with late onset disease, and for them early surgical intervention may not be justified.

Moore-Gillon, J; Eykyn, S J; Phillips, I

1983-01-01

294

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 segment and a plurality of outlet apertures are disposed in the outlet segment. The inlet apertures are disposed in a longitudinally and radially spaced-apart pattern that can be a helix. The outlet apertures are disposed in a corresponding pattern. As the inner member is rotated, whenever an inlet aperture overlaps one of the ducts, the corresponding outlet aperture overlaps a different duct, thus forming a fluid pathway.

Barclay, John A. (Los Alamos, NM); Dyson, Jack E. (Los Alamos, NM)

1985-01-01

295

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

296

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

297

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

298

Aortic valve prosthesis tracking for transapical aortic valve implantation  

Microsoft Academic Search

Purpose  Transapical aortic valve implantation (TA-AVI) is a new minimally invasive surgical treatment of aortic stenosis for high-risk\\u000a patients. The placement of aortic valve prosthesis (AVP) is performed under 2D X-ray fluoroscopic guidance. Difficult clinical\\u000a complications can arise if the implanted valve is misplaced. Therefore, we present a method to track the AVP in 2D X-ray fluoroscopic\\u000a images in order to

M. E. Karar; D. R. Merk; C. Chalopin; T. Walther; V. Falk; O. Burgert

299

Electromagnetic fuel injection valve  

SciTech Connect

An electromagnetic fuel injection valve is described comprising: (a) a housing made of a magnetic material; (b) a valve which opens and closes a fuel injection port that is hydraulically connected to the interior of the housing; (c) a moving core which drives the valve; (d) a fuel guide member which consists of a large diameter portion that is secured to the housing on the side opposite to the fuel injection port. A stationary core extends from the large diameter portion to protrude into the housing. A connection portion extends from the large diameter portion to protrude toward the outer side of the housing, and a penetration path extends from the protruding end of the stationary core to the protruding end of the connection portion; (e) an electromagnetic coil disposed in an annular space defined by the outer periphery of the stationary core and the inner periphery of the housing; (f) a tubular member which is disposed in the penetration path and which has openings at its both ends; and (g) sealing means which hydraulically seals the area between the outer periphery of the tubular member and the inner periphery of the penetration path at an end portion on the side of the fuel injection port of the tubular member.

Soma, M.; Atago, T.; Kido, T.

1986-12-02

300

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

2011-06-19

301

Expeditious diagnosis of primary prosthetic valve failure  

Microsoft Academic Search

Primary prosthetic valve failure is a catastrophic complication of prosthetic valves. Expeditious diagnosis of this complication is crucial because survival time is minutes to hours after valvular dysfunction. The only life-saving therapy for primary prosthetic valve failure is immediate surgical intervention for valve replacement. Because primary prosthetic valve failure rarely occurs, most physicians do not have experience with such patients

Lisa Chan; Timothy Duncan

1999-01-01

302

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

303

Semi-active compressor valve  

SciTech Connect

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

304

Myxoma of the aortic valve  

PubMed Central

Myxomatous tumours can arise from different cardiac structures. They have a special predilection for the left atrium and are an exceedingly uncommon finding in cardiac valves. We report the case of a 28-year old man who presented with a stroke and was found to have a mass arising from his aortic valve. The patient underwent a successful surgical excision of the aortic valve with the implantation of a mechanical prosthesis. The histopathological examination of the aortic valve confirmed the diagnosis of myxoma. Some aspects related to the diagnosis and management of this entity are discussed in this article.

Fernandez, Angel L.; Vega, Marino; El-Diasty, Mohammad M.; Suarez, Jose M.

2012-01-01

305

Double-disc gate valve  

DOEpatents

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

Wheatley, Seth J. (Oak Ridge, TN)

1979-01-01

306

Experience with Willis choke valves  

SciTech Connect

The model M1HT valve manufactured by the Willis Oil Tool Company has been successfully used in wells producing crude oil and raw natural gas and in some coal gasification plants. In coal liquefaction pilot plants, this type of valve also has met with some success as a block valve, but in situations requiring a flow throttling action, it has not performed well. Experiences with these choked disc valves at the Fort Lewis SRC Pilot Plant and at the H-Coal Pilot Plant are presented in an attempt to provide some reasons for their poorer performance in letdown service. 1 figure.

Dahl, T.L.

1982-12-01

307

49 CFR 195.116 - Valves.  

Code of Federal Regulations, 2011 CFR

... TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Design Requirements § 195.116 Valves. Each valve...the following: (a) The valve must be of a sound engineering design. (b) Materials subject to the internal...

2011-10-01

308

49 CFR 229.109 - Safety valves.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Safety valves. 229.109 Section 229...Steam Generators § 229.109 Safety valves. Every steam generator shall be equipped with at least two safety valves that have a combined...

2010-10-01

309

14 CFR 125.137 - Oil valves.  

Code of Federal Regulations, 2013 CFR

...Requirements § 125.137 Oil valves. (a) Each oil valve mustâ (1) Comply with § 125...transmitted to the lines attached to the valve. (b) The closing of an...propeller, unless equivalent safety provisions are...

2013-01-01

310

49 CFR 229.109 - Safety valves.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Safety valves. 229.109 Section 229...Steam Generators § 229.109 Safety valves. Every steam generator shall be equipped with at least two safety valves that have a combined...

2009-10-01

311

14 CFR 121.239 - Oil valves.  

Code of Federal Regulations, 2013 CFR

...Requirements § 121.239 Oil valves. (a) Each oil valve mustâ (1) Comply with § 121...transmitted to the lines attached to the valve. (b) The closing of an...the propeller, unless equivalent safety provisions are...

2013-01-01

312

Whitey Gauge and Root Valves (VPS)  

SciTech Connect

These valves are 1/2-inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as isolation valves for pressure instrumentation in the Vacuum Pumping and Helium System.

MISKA, C.

2000-10-17

313

49 CFR 195.420 - Valve maintenance.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Valve maintenance. 195.420 Section 195...Operation and Maintenance § 195.420 Valve maintenance. (a) Each operator shall maintain each valve that is necessary for the safe...

2012-10-01

314

49 CFR 195.420 - Valve maintenance.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Valve maintenance. 195.420 Section 195...Operation and Maintenance § 195.420 Valve maintenance. (a) Each operator shall maintain each valve that is necessary for the safe...

2011-10-01

315

Dual Valve Plate Two-Way Pressure Relief Valve.  

National Technical Information Service (NTIS)

This patent application discloses a two-way valve which includes dual valve plates to be positioned between first and second chambers having varying pressure therein, to relieve excess pressure in either chamber by permitting fluid flow from one chamber t...

R. J. Angeli

1993-01-01

316

5. STILLING BASIN FOR VALVE HOUSE AND ROOF OF VALVE ...  

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

5. STILLING BASIN FOR VALVE HOUSE AND ROOF OF VALVE HOUSE IN PHOTO CENTER, SPILLWAY CHANNEL (lined and unlined at left of photo), LOOKING NORTHEAST - Tieton Dam, Spillway & Drum Gates, South & East side of State Highway 12, Naches, Yakima County, WA

317

High temperature ultrahigh vacuum valves. Final report  

Microsoft Academic Search

All-metal valves heatable up to 300 to 400°C in closed and open position were developed for handling aggressive gases such as UFâ in high vacuum technology. Sealing aspects of valves with large nominal width, such as transfer valve NW 150 and corner valve 150, and of valves with small nominal width, such as corner valves NW 6, 16, 35, and

W. Baechler; G. Jokisch; H. P. Kabelitz; K. Teutenberg

1976-01-01

318

Acoustic monitoring of power-plant valves  

Microsoft Academic Search

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

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

1982-01-01

319

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

SciTech Connect

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

VANDYKE, D.W.

1999-08-25

320

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

SciTech Connect

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

VANDYKE, D.W.

1999-08-25

321

Rotary selector valve  

SciTech Connect

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 formed with an endless groove to receive an O-ring. An actuating shaft is coaxially mounted in an upper end of the trunnion and has a lower end with an eccentric pin engaged in a slot of the seal piston to reciprocate the seal piston into and out of sealing registration around a port selected by rotation of the trunnion. External ends of the actuating shaft and trunnion are respectively drivably coupled to a coaxial sprocket wheel and geneva wheel. A housing on top of the valve contains an input rotor fitted with a cam and a drive roller for engaging radial slots of the geneva wheel alternately with cam engagement of the dwell notches of the geneva wheel. Concurrently and in advance of forward rotation of the geneva wheel, a rotor driven seal actuating yoke a free end engages one of a series of radial slots of the sprocket to rotate the sprocket in a retrograde direction to disengage the seal. When the yoke is disengaged, a detent mechanism temporarily locks the geneva and sprocket wheels together for co-rotation in a forward direction as the geneva drive roller again comes into engagement with the geneva wheel. After the nozzle has been advanced one step, further rotation of the input rotor advances an arm independently pivotally mounted on the yoke to compress a spring mechanism to bias the yoke and sprocket to compress the seal on a seat around the next port.

Jones, J.A.; Herndon, J.W.

1991-02-05

322

Design and control of an electromagnetic valve actuator  

Microsoft Academic Search

In this paper we present theoretical and experimental results for designing and operating a special linear electromagnetic motor as a variable engine valve actuator. Detailed description is given to the design procedure to meet the requirements of high dynamic and low power consumption, including the determination of actuator topology and parameters, the force, dynamic and power loss calculations. Based on

Steffen Braune; Steven Liu; Paolo Mercorelli

2006-01-01

323

21 CFR 870.3925 - Replacement heart valve.  

Code of Federal Regulations, 2010 CFR

...perform the function of any of the heart's natural valves. This device includes valves constructed of prosthetic materials, biologic valves (e.g., porcine valves), or valves constructed of a combination of prosthetic and biologic...

2010-04-01

324

21 CFR 870.3925 - Replacement heart valve.  

Code of Federal Regulations, 2010 CFR

...perform the function of any of the heart's natural valves. This device includes valves constructed of prosthetic materials, biologic valves (e.g., porcine valves), or valves constructed of a combination of prosthetic and biologic...

2009-04-01

325

High pressure air compressor valve fault diagnosis using feedforward neural networks  

Microsoft Academic Search

Feedforward neural networks (FNNs) are developed and implemented to classify a four-stage high pressure air compressor into one of the following conditions: baseline, suction or exhaust valve faults. These FNNs are used for the compressor’s automatic condition monitoring and fault diagnosis. Measurements of 39 variables are obtained under different baseline conditions and third-stage suction and exhaust valve faults. These variables

C. James Li; Xueli Yu

1995-01-01

326

Awake transapical aortic valve implantation.  

PubMed

Transapical aortic valve implantation is being employed as a less invasive alternative to open heart surgery in high-risk patients with severe aortic stenosis. Here we report the case of an awake transapical aortic valve implantation in a patient with severe chronic obstructive pulmonary disease. PMID:22345062

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

2012-02-16

327

Exhaust gas recirculation control valve  

Microsoft Academic Search

An exhaust gas recirculation control valve for preventing carbon and the like contained in the exhaust gas from attaching to the inner wall surface of exhaust gas paths, through which the exhaust gas from an engine of a motor car passes, thus decreasing the diameters of the paths with time. This exhaust gas recirculation control valve is provided in a

Masuda

1982-01-01

328

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

329

Prosthetic valve endocarditis. A survey.  

PubMed Central

Fifty eight patients (aged 8-59 years, mean 27) treated for prosthetic valve endocarditis from January 1966 to January 1985 were studied retrospectively by review of case notes. There were 12 cases of early and 46 cases of late prosthetic valve endocarditis. These developed in 28 patients with an isolated aortic valve, in 26 with an isolated mitral valve, and in four with both aortic and mitral prosthetic valves. Streptococci were the most commonly isolated microorganisms, followed by staphylococci, Gram negative bacteria, and fungi. A surgical (34 cases) or a necropsy specimen (10 cases) from 44 cases was examined. Eighty two per cent of the patients had congestive heart failure. Twenty four of the 58 patients were medically treated and 17 died (70% mortality). Combined medical and surgical treatment was used in 34 patients; the main indication for surgery was congestive heart failure. Fourteen patients on combined treatment died (40% mortality). Persistent sepsis and prosthetic valve dehiscence were the most common early and late operative complications. The most important influences on outcome were congestive heart failure, the type of micro-organism, the severity and extent of anatomical lesions, the time of onset of prosthetic valve endocarditis, and the type of treatment. This survey indicates that only patients without congestive heart failure or embolic complications and with sensitive micro-organism should be treated medically. In view of the poor prognosis patients with prosthetic valve endocarditis associated with congestive heart failure, persistent sepsis, and repeat arterial emboli should be treated by early surgical intervention.

Ben Ismail, M; Hannachi, N; Abid, F; Kaabar, Z; Rouge, J F

1987-01-01

330

Leakage Rates for Cryolab Valves  

Microsoft Academic Search

This note summarizes a brief study on the leakage rates of cryolab valves due to the failure of the valve packings. The r gap between the shaft and the packing, the fluid (Ar or N2), the p (atm) between the fluid and atmosphere, and the initial temperature of the escaping gas were varied to determine the resulting leakage rate. The

J. M. Wendlandt

1988-01-01

331

Valve Stem and Packing Assembly.  

National Technical Information Service (NTIS)

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 mean...

J. J. Wordin

1990-01-01

332

Valve stem and packing assembly.  

National Technical Information Service (NTIS)

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 mean...

J. J. Wordin

1990-01-01

333

Butterfly valve apparatus and method  

SciTech Connect

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

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

1990-10-23

334

Cavitation guide for control valves  

Microsoft Academic Search

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

Tullis

1993-01-01

335

A Parylene MEMS Electrothermal Valve.  

PubMed

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

2009-12-01

336

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

337

Prototype lockhopper valve test plan  

SciTech Connect

This document has been prepared to summarize the overall plan for testing prototype lockhopper valves being developed by Fairchild Industries and Consolidated Controls Corporation under contract to DOE/FE. The testing effort described will establish the capability of these valves to meet the design criteria contained in Design Criteria for Lockhopper Valve Development, METC/SP-78/3. The design criteria was based on the requirements of the Lockhopper Valve RFP 1813, analysis of those coal conversion processes that are most promising for demonstration plants, and a desire for valve life comparable with other gasification plant equipment. The test plan was prepared with inputs from, and in cooperation with, Fossil Energy Research and Morgantown Energy Technology Center personnel and was originally published on December 30, 1976, under Fossil Energy Report FE 2213-016-09 by TRW Energy Systems Group.

Gardner, J.F.; Freeburn, F.D.

1979-03-01

338

High flow check valve apparatus  

SciTech Connect

A check valve apparatus is provided for high volume fluid conduits such as a casing string of an oil well. In order to maximize the fluid delivered from the well, it is essential that the restrictions imposed on the fluid flow path by necessary components in the casing string, such as a standing check valve, provide as little as possible interference with the flow area. This invention provides a valving arrangement including longitudinally extending, separated, parallel fluid inlet and outlet passages interconnected by a plurality of ball valve chambers, with each chamber defining a transverse ball seat and containing a ball cooperating with such seat. The fluid area of the inlet passage decreases from the first chamber to the last in the direction of fluid flow while the fluid area of the outlet passage increases from the first chamber to the last, so that the total fluid area passage through the plurality of valves in their open position is maximized.

Erickson, J.W.

1981-03-03

339

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.

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

2011-01-01

340

[The physical rehabilitation at a sanatorium of patients wearing aortic valve prostheses].  

PubMed

Methods and results of physical rehabilitation of 81 patients with prostheses of the aortal valve in conditions of a health resort are reported. The authors revealed a 29.2% increase of physical, working capacity and a reduction (8.2%) of oxygen expenditures per unit of work. Increase of intensity of training loads improved the results of physical rehabilitation. The role of health resort treatment in the system of postoperative rehabilitation of patients with heart valve prostheses is emphasized. PMID:2256276

Bendet, Ia A; Ovcharova, M V

1990-08-01

341

Dump valve for use with downhole motor  

SciTech Connect

A dump valve having a valve seat and a valve member is located in a string of drill pipe above a downhole motor. The dump valve connects the inside of the drill string with the annulus and allows drilling mud to flow freely therebetween when drilling mud is not being pumped through the drill string to operate the downhole motor. The valve member is made of a deformable resilient material such as rubber. It is held away from the valve seat by spacers until the pressure drop across the valve member is sufficient to deform the valve member and move it past the spacers into engagement with the valve seat. When the pressure differential is relieved, the valve member will return to its normal, unstressed shape opening the valve.

Poston, J.B.

1981-03-31

342

FLUID MECHANICS OF ARTIFICIAL HEART VALVES  

PubMed Central

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

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

2009-01-01

343

Fluid mechanics of artificial heart valves.  

PubMed

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

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

2009-02-01

344

Patents and heart valve surgery - II: tissue valves.  

PubMed

Valvular heart disease affects millions of Americans yearly and currently requires surgical intervention to repair or replace the defective valves. Through a close-knit collaboration between physicians, scientists and biomedical engineers, a vast degree of research and development has been aimed towards the optimization of prosthetic heart valves. Although various methods have made fantastic strides in producing durable prostheses, the therapeutic efficacy of prosthetic valves is inherently limited by a dependency upon lifelong anticoagulant regimens for recipients - a difficult challenge for many in clinical setting. Thus, biological tissue valves have been developed to circumvent vascular and immunemediated complications by incorporating biological materials to mimic native valves while still maintaining a necessary level of structural integrity. Over the past decade, a multitude of patents pertaining to the refinement of designs as well as the advancement in methodologies and technologies associated with biological tissue valves have been issued. This review seeks to chronicle and characterize such patents in an effort to track the past, present, and future progress as well as project the trajectory of tissue valves in the years to come. PMID:23919429

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

2013-08-01

345

46 CFR 160.151-39 - Training of servicing technicians.  

Code of Federal Regulations, 2012 CFR

...certification of servicing technicians must includeâ (1) Training and practice in packing an inflatable liferaft, repairing buoyancy tubes, repairing inflation-system valves, and other inspections and operations described in the approved servicing...

2012-10-01

346

Simultaneous, long-term monitoring of valve and cardiac activity in the blue mussel Mytilus edulis exposed to copper  

Microsoft Academic Search

Valve and cardiac activity were simultaneously measured in the blue mussel (Mytilus edulis) in response to 10?d copper exposure. Valve movements, heart rates and heart-rate variability were obtained non-invasively\\u000a using a Musselmonitor® (valve activity) and a modified version of the Computer-Aided Physiological Monitoring system (CAPMON; cardiac activity).\\u000a After 2?d exposure of mussels (4 individuals per treatment group) to a range

T. M. Curtis; R. Williamson; M. H. Depledge

2000-01-01

347

DEVELOPMENT OF A SENSOR-LESS ELECTRO-HYDRAULIC VALVE ACTUATOR FOR A CAM-LESS ENGINE  

Microsoft Academic Search

A fully electronically controllable valve-actuator has potentials of improving volumetric efficiency at gas exchange, and of presenting variable compression-ratio. This paper describes a new type of hydro-mechanical position-servo electro-hydraulic valve actuator for a cam-less engine. The piston is positioned hydro mechanical feedback mechanism, which balances the flow rate of the feedback slot to the pilot valve. The feedback-slot opens its

Hirohisa TANAKA; Nozomi TOYODA

2005-01-01

348

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

349

Prototype lockhopper valve testing and development  

SciTech Connect

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 approach was to compare prototype designs with existing commercial valves, evaluate prototype lockhopper valves under simulated conditions, provide test data to improve designs, verify any design modification improvements, and finally to test valves under pilot or demonstration plant conditions. Valve performance was evaluated on whether the valve met or exceeded the operational goals. Valve performance was compared to the performance of valves tested in the State-of-the-Art (SOA) Valve Program (Ayers and Wojewodka, 1985). The Fairchild Control Systems (FCS) valves were the most successful; however even these valves, regardless of type, experienced operational problems. The FCS high temperature Type III valve had the best performance. The valve operated successfully in an erosive stream of silicon carbide with solid temperatures of up to 1800/sup 0/F. The success of this valve was attributed to the abrasion resistance of the boron carbide valve seat and its small thermal expansion. However, the valve will require a significant amount of redesign to be commercially viable. The other FCS valve types did not significantly surpass or in some cases equal the performance of SOA or commercially available valves exposed to similar conditions. 19 refs., 34 figs., 8 tabs.

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

1985-07-01

350

Flashing water flow through a safety valve  

Microsoft Academic Search

This paper presents an analysis of flashing and non-flashing water flows through a safety relief valve. A set of experiments has been carried out on the CROSBY safety valve and its model. The pressure distributions inside the valve, the inlet and outlet temperatures and the mass-flow rates (critical or otherwise) have been measured. The characteristics of the valve giving the

L. Bolle; P. Downar-Zapolski; J. Franco; J. M. Seynhaeve

1995-01-01

351

Prosthetic Heart Valve Thrombosis: An Overview  

Microsoft Academic Search

Background: Valvular heart disease represents a sig- nificant burden to patients with cardiovascular dis- eases. Surgical treatment of diseased heart valves represents a significant advancement for these pa- tients. However, there are specific complications related to prosthetic valves, including valve throm- bosis. Methods: Review article. Results: Thrombosis of a prosthetic heart valve can present with gradual cardiac decline, embolic phe-

Robert S. Dieter; Raymond A. Dieter; John P. Pacanowski; Micheal J. Costanza; William W. Chu; Eugene A. Gulliver Jr

352

[Bicuspid aortic valve].  

PubMed

Bicuspid aortic valve (BAV) is the most common congenital heart disease, whose natural history is characterized by the incidence of clinically relevant valvular (stenosis, regurgitation, endocarditis) and/or vascular complications regarding the thoracic aorta (dilation, aneurysm, dissection) and, rarely, intracranial and epiaortic arteries. BAV may be heritable, with an autosomal dominant pattern of inheritance with reduced penetrance; moreover, some data suggest that BAV and thoracic aorta aneurysm are independent manifestations of a single gene defect. The prevalence of BAV and its susceptibility to valvular and aortic complications during the whole life result into the need of strict clinical follow-up and appropriate therapies (medical as well as surgical) to be addressed according to guidelines specifically designed for these patients. PMID:22322469

Nistri, Stefano; Basso, Cristina; Thiene, Gaetano

2012-01-01

353

Age-dependent changes of heart valves and heart size.  

PubMed

The mode and extent of the regressions of heart valves, valvular rings, and tendon chords, as well as the size of atria and ventricles in 316 hearts of different age groups (macroscopically normal at autopsy), were studied. With increasing age, the valves showed marked thickening and loss of elasticity. Deposition of lipoids and calcification occur to a variable extent in the valvular tissue and rings; Valve size shows a change of minor degree, but tendon chords and papillary muscles shorten in old age. The diameters of the atria, mitral, tricuspid, pulmonary, and aortic rings increase continuously up to the 9th decade of life. The width and length of the ventricles show minor alterations in size. In old age, heart weight increases. PMID:1209008

Schenk, K E; Heinze, G

1975-01-01

354

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

355

Mitral valve replacement in dogs using pig aortic valve heterografts  

Microsoft Academic Search

Mitral valve replacement using pig aortic valve heterografts has been performed in 27 dogs, siting the grafts in the `atrial position'. Buffered acid formaldehyde sterilization offered the advantages that it is simple and, by de-naturing the proteins of the graft, may minimize `rejection' phenomena. It may offer some self-sterilizing property to the graft within the host post-operatively. The question whether

David I. Hamilton; Frank Gerbode

1968-01-01

356

Anterior urethral valve associated with posterior urethral valves  

Microsoft Academic Search

The association of anterior urethral valve (AUV) with posterior urethral valve (PUV) is rare. A 7-month-old infant was presented at a district hospital with episodes of acute pyelonephritis. He was treated medically and a voiding cystourethrogram (VCUG) confirmed bilateral vesico-urethral reflux. The presence of concomitant AUV and PUV was not recognized. He underwent several surgical procedures, which failed. He had

A. M. Kajbafzadeh; P. Jangouk; C. Ahmadi Yazdi

2005-01-01

357

Computer aided detection of endobronchial valves  

NASA Astrophysics Data System (ADS)

The ability to automatically detect and monitor implanted devices may serve an important role in patient care and the evaluation of device and treatment efficacy. The purpose of this research was to develop a system for the automated detection of one-way endobronchial valves implanted as part of a clinical trial for less invasive lung volume reduction. Volumetric thin section CT data was obtained for 275 subjects; 95 subjects implanted with 246 devices were used for system development and 180 subjects implanted with 354 devices were reserved for testing. The detection process consisted of pre-processing, pattern-recognition based detection, and a final device selection. Following the pre-processing, a set of classifiers were trained using AdaBoost to discriminate true devices from false positives (such as calcium deposits). The classifiers in the cascade used simple features (the mean or max attenuation) computed near control points relative to a template model of the valve. Visual confirmation of the system output served as the gold standard. FROC analysis was performed for the evaluation; the system could be set so the mean sensitivity was 96.5% with a mean of 0.18 false positives per subject. These generic device modeling and detection techniques may be applicable to other devices and useful for monitoring the placement and function of implanted devices.

Ochs, Robert A.; Goldin, Jonathan G.; Abtin, Fereidoun; Ghurabi, Raffi; Rao, Ajay; Ahmad, Shama; da Costa, Irene; Brown, Matthew

2008-04-01

358

Valve Drive Electronics Assembly (VDA).  

National Technical Information Service (NTIS)

The design of a prototype redundant valve drive electronics assembly (VDA) is discussed. The VDA is used as part of the modular attitude and control system for the electrical actuation and monitoring of spacecraft reaction control assemblies (RCA). The ma...

M. Aulagnon M. Duban M. Reinhalter

1978-01-01

359

Models of aortic valve calcification.  

PubMed

Aortic valve stenosis is a complex inflammatory process, akin to arterial atherosclerosis, involving lymphocytic infiltrates, macrophages, foam cells, endothelial activation and dysfunction, increased cellularity and extracellular matrix deposition, and lipoprotein accumulation. A clonal population of aortic valve myofibroblasts spontaneously undergoes phenotypic transdifferentiation into osteoblast-like cells and forms calcific nodules in cell culture. Animal models complement these cell culture models by providing in vivo systems in which to study the complex molecular and cellular interactions that cause aortic valve disease in the native hemodynamic and biochemical environment. Whereas some species, such as swine, can develop spontaneous vascular and valvular atherosclerotic lesions, others, such as rabbits and mice, have not been shown to develop lesions naturally and require an inciting factor, such as hypercholesterolemia. In this article, we review the published cell culture and animal models available to study calcific aortic valve disease. PMID:17963676

Guerraty, Marie; Mohler Iii, Emile R

2007-09-01

360

Options for Heart Valve Replacement  

MedlinePLUS

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

361

Aortic valve stenosis after previous coronary bypass: Transcatheter valve implantation or aortic valve replacement?  

PubMed Central

We report a prospective comparison between transcatheter valve implantation (TAVI, n?=?13) and surgical aortic valve replacement (AVR, n?=?10) in patients with severe aortic valve stenosis and previous coronary bypass surgery (CABG). All patients had at least bilateral patent internal thoracic arteries bypass without indication of repeat revascularization. After a similar post-procedure outcome, despite one early death in TAVI group, the 1-year survival was 100% in surgical group and in transfemoral TAVI group, and 73% in transapical TAVI group. When previous CABG is the lone surgical risk factor, indications for a TAVI procedure have to be cautious, specially if transfemoral approach is not possible.

2012-01-01

362

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Alternative standards for valves-allowable percentage of valves leaking. 60.483-1 Section 60.483-1...2006 § 60.483-1 Alternative standards for valvesâallowable percentage of valves leaking....

2013-07-01

363

Short-term effect of monocuspid valves on pulmonary insufficiency and clinical outcome after surgical repair of tetralogy of fallot  

Microsoft Academic Search

In the surgical repair of tetralogy of Fallot, monocuspid valves are sometimes inserted within a transannular patch to prevent pulmonary insufficiency. To determine whether this monocuspid valve prevents short-term postoperative pulmonary insufficiency and improves clinical outcome, we reviewed clinical data and preoperative and postoperative echocardiographic variables from 61 patients who underwent one of three different procedures for repair of tetralogy

Jean-Luc Bigras; Christine Boutin; Brian W. McCrindle; Ivan M. Rebeyka

1996-01-01

364

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

365

Minimally invasive mitral valve surgery  

Microsoft Academic Search

Like many other surgical specialties, cardiac surgery is evolving toward more minimally invasive approaches. Mitral valve\\u000a surgery has been shown to be feasible and safe when performed through smaller incisions or with the aid of robotic manipulation.\\u000a Recent technologic advances allow complex mitral valve reconstruction to be carried out through these small incisions with\\u000a avoidance of a full sternotomy and

Sunil Panwar; Edward G. Soltesz

2008-01-01

366

Failsafe gas closed safety valve  

SciTech Connect

A subsurface well safety valve is described for controlling the fluid flow through a well conduit comprising: a housing having a bore; a valve closure member moving between open and closed positions for controlling the fluid flow through the bore; a flow tube telescopically moving in the housing for controlling the movement of the valve closure member; a piston and cylinder assembly positioned in the housing and one of the piston and cylinder engages the flow tube, a first side of the assembly adapted to be in communication with a fluid control passageway to the well surface; a gas chamber in the housing in communication with the second side of the assembly acting on the assembly in a direction to close the valve; spring means between the housing and the flow tube acting on the flow tube in a direction to close the valve; seal means between the piston and cylinder; and openable and closable equalizing means for equalizing fluid pressure on opposite sides of the piston and cylinder assembly in the event of a failure in the seal means thereby allowing the spring means to close the valve.

Blizzard, W.A.

1987-04-28

367

PERIOSTIN REGULATES ATRIOVENTRICULAR VALVE MATURATION  

PubMed Central

Cardiac valve leaflets develop from rudimentary structures termed endocardial cushions. These pre-valve tissues arise from a complex interplay of signals between the myocardium and endocardium whereby secreted cues induce the endothelial cells to transform into migratory mesenchyme through an endothelial to mesenchymal transformation (EMT). Even though much is currently known regarding the initial EMT process, the mechanisms by which these undifferentiated cushion mesenchymal tissues are remodeled “post-EMT” into mature fibrous valve leaflets remains one of the major, unsolved questions in heart development. Expression analyses, presented in this report, demonstrate that periostin, a component of the extracellular matrix, is predominantly expressed in post-EMT valve tissues and their supporting apparatus from embryonic to adult life. Analyses of periostin gene targeted mice demonstrate that it is within these regions that significant defects are observed. Periostin null mice exhibit atrial septal defects, structural abnormalities of the AV valves and their supporting tensile apparatus, and aberrant differentiation of AV cushion mesenchyme. Rescue experiments further demonstrate that periostin functions as a hierarchical molecular switch that can promote the differentiation of mesenchymal cells into a fibroblastic lineage while repressing their transformation into other mesodermal cell lineages (e.g. myocytes). This is the first report of an extracellular matrix protein directly regulating post-EMT AV valve differentiation, a process foundational and indispensable for the morphogenesis of a cushion into a leaflet.

Norris, Russell A.; Moreno-Rodriguez, Ricardo A.; Sugi, Yukiko; Hoffman, Stanley; Amos, Jenny; Hart, Mary M.; Potts, Jay D.; Goodwin, Richard L.; Markwald, Roger R.

2008-01-01

368

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

369

[Historical evolution of prosthetic heart valves].  

PubMed

The historical evolution of the prosthetic heart valves is resumed, quoting the first experimental steps, the conditions that a prosthesis has to fulfil, and the first clinical attempts with the Hufnagel's valve in the treatment of the aortic insufficiency (September 11, 1952) and with the Chesterman's in the pathology of the mitral valve (July 22, 1955) till the Starr Edwards' ball valve (Agoust 12, 1960). The characteristics of the different types of ball valve are described (Harken, Smeloff, etc), disc valves (Kay-Shiley, Beall, Lillehei-Nakib etc.), tilting disc valves (Bjork-Shiley, Hall-Kaster, Omniscience etc), bileaflet valves ( St. Jude and others) and biological valves, using autologous tisues (diaphragm, fascia lata, pericardium) homologous (aortic and mitral valves, duramater) and heterologous (porcine and bovine valves, Carpentier-Edwards, Hancock, Ionescu's valve of bovine pericardium), to conclude with the new trends with valves made from autologous cells, the valves made with polymers, those based on the concept of flexible tubes and finally with those used by percutaneous transcatheter implantation (Boudjemline y Bonhoeffer. Cribier.). PMID:17451095

Tamames Escobar, Santiago

2006-01-01

370

Transcatheter aortic valve implantation: a Canadian Cardiovascular Society position statement.  

PubMed

Patients with severe symptomatic aortic stenosis have a poor prognosis with medical management alone, and balloon aortic valvuloplasty has failed to provide durable clinical benefit. Open surgical replacement of the aortic valve can improve symptoms and survival. Recently, transcatheter aortic valve implantation (TAVI) has been demonstrated to improve survival, quality of life, and functional status in nonoperable patients and to be a viable option for patients in whom the risk of open surgical morbidity or mortality is high. This Canadian Cardiovascular Society position statement represents the consensus of a representative group of cardiologists and cardiac surgeons as to the current, but evolving, role of this less-invasive new therapy. Specific recommendations are provided for selection of patients for TAVI vs surgical aortic valve replacement for native valves and for bioprostheses, approaches to patient evaluation for TAVI, appropriate constitution of multidisciplinary teams involved in performing TAVI, essential facilities that are needed to perform TAVI safely and effectively, and training/qualifications for TAVI operators. Cost considerations, complication rates, and the quality of the available evidence are also discussed. It is hoped that this consensus document will prove to be a useful resource for health professionals, institutions, departments, and decision-making bodies dealing with this important and rapidly evolving therapy. PMID:22703948

Webb, John; Rodés-Cabau, Josep; Fremes, Stephen; Pibarot, Philippe; Ruel, Marc; Ibrahim, Reda; Welsh, Robert; Feindel, Christopher; Lichtenstein, Samuel

2012-06-15

371

Valve operating system for internal combustion engine  

SciTech Connect

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 to open and close the intake and exhaust passages, respectively, and a valve operating mechanism having an intermittent operating function of rotatively driving the valve bodies of the intake and exhaust rotary valves in response to movement of the piston to provide an opening and closing control for the intake and exhaust rotary valves, and holding the rotary valve bodies in valve-opening and closing positions for respective predetermined periods of time, wherein the valve operating mechanism includes cam means adapted to be continuously rotated in one direction in response to the movement of the piston, rocker arms abutting the cam means and adapted to swing within a predetermined angle in accordance with the rotation of the cams, and rotary shafts each having one of the spherical valve bodies secured to one of the opposite ends thereof and adapted to reciprocally rotate between the valve-opening and closing positions of the valve body around an axis of the rotary shaft in accordance with the swinging movement of the rocker arm upon receiving a driving force from the rocker arm on the other end thereof, and the spherical valve bodies being each supported within the cylinder head through a valve seat member, and a seal spring being interposed between the valve seat member and the cylinder head.

Matsuura, M.; Nakamori, M.; Kuroki, M.

1988-10-11

372

A randomized controlled trial in a training institution comparing a pediatric variable stiffness colonoscope, a pediatric colonoscope, and an adult colonoscope  

Microsoft Academic Search

Background: There are few comparative data on the efficacy of different colonoscopes. This study compared the efficacy of a new pediatric variable stiffness colonoscope with that of standard pediatric and adult colonoscopes in the performance of routine colonoscopy. Methods: Three hundred sixty-three consecutive patients were randomized to undergo colonoscopy with a pediatric variable stiffness (n = 122), pediatric (n =

Douglas A. Shumaker; Atif Zaman; Ronald M. Katon

2002-01-01

373

Software Enabled Virtually Variable Displacement Pumps - Theoretical and Experimental Studies  

Microsoft Academic Search

A hydro-mechanical analog of an electronic DC-DC boost converter is developed to create the functional equivalent of a variable displacement pump. This approach combines a fixed displacement pump with a pulse-width-modulated (PWM) on\\/off valve, a check valve, and an accumulator. Since on\\/off valves exhibit low loss when fully open or fully closed, the proposed system is more energy efficient than

Michael B. Rannow; Haink C. Tu; Perry Y. Li; Thomas R. Chase

374

Internal jugular vein valves: an assessment of prevalence, morphology and competence by color Doppler echography in 240 healthy subjects.  

PubMed

The presence of valves in the head and neck veins is known since classical anatomical dissections. Previous studies have investigated whether jugular veins show constant valves at their ostium and whether these valves are physiologically competent, but, unluckily, these studies have reported conflicting results. Further, recent observations have raised the question whether the incompetence of jugular vein valves might play a pivotal role in neurological disorders related to venous engorgement of the brain. In this study we examined 462 internal jugular veins by using an echocolorodoppler apparatus. In particular, we assessed the presence, morphology and competence of valves at their ostium. Unilateral jugular vein valves were present in 406 cases (88%), mainly on the right side. The most frequently observed morphology (75%, 305 cases) was the two-leaflet valve, and jugular vein valves were incompetent in the huge majority of cases (365 cases, 90%). Our findings confirm the anatomical variability predicted from classical anatomical studies but, unluckily, do not provide additional evidence on the possible role of jugular vein valves in physiology and pathology. Further studies are strongly needed to determine whether these valves actually play an important role in counteracting chest venous pressure and in preventing reflux towards the brain. PMID:21287973

Valecchi, Debora; Bacci, Duccio; Gulisano, Massimo; Sgambati, Eleonora; Sibilio, Maurizio; Lipomas, Mario; Macchi, Claudio

2010-01-01

375

Programmable valve shunts: are they really better?  

PubMed

Programmable valve shunts allows selection of opening pressure of shunt valve. In the presented article, a unique complication pertaining to programmable shunts has been discussed. A 5-year-old boy who had tectal plate low grade glioma with obstructive hydrocephalus was managed with Codman programmable ventriculoperitoneal shunt. There was a spontaneous change in the opening pressure of the shunt valve leading to shunt malfunction. Routinely used household appliances produce a magnetic field strong enough to cause change in the setting of shunt valve pressure and may lead to valve malfunction. Other causes of programmable valve malfunction also discussed. PMID:22437300

Kataria, Rashim; Kumar, Vimal; Mehta, Veer Singh

2012-01-01

376

Automatic aorta segmentation and valve landmark detection in C-arm CT: application to aortic valve implantation.  

PubMed

C-arm CT is an emerging imaging technique in transcatheter aortic valve implantation (TAVI) surgery. Automatic aorta segmentation and valve landmark detection in a C-arm CT volume has important applications in TAVI by providing valuable 3D measurements for surgery planning. Overlaying 3D segmentation onto 2D real time fluoroscopic images also provides critical visual guidance during the surgery. In this paper, we present a part-based aorta segmentation approach, which can handle aorta structure variation in case that the aortic arch and descending aorta are missing in the volume. The whole aorta model is split into four parts: aortic root, ascending aorta, aortic arch, and descending aorta. Discriminative learning is applied to train a detector for each part separately to exploit the rich domain knowledge embedded in an expert-annotated dataset. Eight important aortic valve landmarks (three aortic hinge points, three commissure points, and two coronary ostia) are also detected automatically in our system. Under the guidance of the detected landmarks, the physicians can deploy the prosthetic valve properly. Our approach is robust under variations of contrast agent. Taking about 1.4 seconds to process one volume, it is also computationally efficient. PMID:20879265

Zheng, Yefeng; John, Matthias; Liao, Rui; Boese, Jan; Kirschstein, Uwe; Georgescu, Bogdan; Zhou, S Kevin; Kempfert, Jörg; Walther, Thomas; Brockmann, Gernot; Comaniciu, Dorin

2010-01-01

377

Comparison of aortic root measurements in patients undergoing transapical aortic valve implantation (TA-AVI) using three-dimensional rotational angiography (3D-RA) and multislice computed tomography (MSCT): differences and variability.  

PubMed

To evaluate for the first time the degree of compliance between conventional multislice computed tomography (MSCT) and three-dimensional rotational angiography (3D-RA) in measuring relevant dimensions of the aortic annulus, the aortic root and the thoracic aorta in patients undergoing TA-AVI. Twenty-seven patients (82 ± 11 years) with severe aortic stenosis received contrast enhanced ECG gated MSCT prior to TA-AVI and intra-procedural rotational angiography. The aortic annulus size, the distance to the coronary ostia and diameters of the aortic root and the thoracic aorta were measured with both methods by two observers blinded to each other. Linear regression and Bland-Altman analysis were performed to determine the degree of compliance between both methods. The limits of agreement were within two standard deviations for all measurements and with high correlation especially for the supra-annular dimensions. Sizing of the aortic annulus revealed lower interobserver variability for MSCT than for 3D-RA with a maximum deviation of 2.1 ± 2.5 and 1.7 ± 2.8 mm for diameter measurements and for the effective diameter, respectively. With current protocols intra-procedural 3D-RA provides good image quality especially for structures above the aortic annulus. Due to a lower interobserver variability in sizing the aortic annulus MSCT remains more suitable for aortic root assessment prior to TA-AVI. PMID:22710987

Lehmkuhl, Lukas H J; von Aspern, Konstantin; Foldyna, Borek; Grothoff, Matthias; Nitzsche, Stefan; Kempfert, Joerg; Rastan, Ardawan; Linke, Axel; Mohr, Friedrich W; Noettling, Alois; Walther, Thomas; Gutberlet, Matthias

2012-06-19

378

SOFTWARE ENABLED VARIABLE DISPLACEMENT PUMPS  

Microsoft Academic Search

Direct pump control of hydraulic systems is more energy efficient than throttle valve based methods to control hydra ulic systems. This requires variable displacement pumps that are responsive and capable of electronic control. Such Electronic Displacement Controlled (EDC) pumps tend to be significantl y larger, heavier and more expensive than fixed displacement c oun- terparts. In addition, achievable control bandwidths

Perry Y. Li; Cassie Y. Li; Thomas R. Chase

379

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

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

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

380

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

381

Failure and life cycle evaluation of watering valves.  

PubMed

Automated watering systems provide a reliable source of ad libitum water to animal cages. Our facility uses an automated water delivery system to support approximately 95% of the housed population (approximately 14,000 mouse cages). Drinking valve failure rates from 2002 through 2006 never exceeded the manufacturer standard of 0.1% total failure, based on monthly cage census and the number of floods. In 2007, we noted an increase in both flooding and cases of clinical dehydration in our mouse population. Using manufacturer's specifications for a water flow rate of 25 to 50 mL/min, we initiated a wide-scale screening of all valves used. During a 4-mo period, approximately 17,000 valves were assessed, of which 2200 failed according to scoring criteria (12.9% overall; 7.2% low flow; 1.6% no flow; 4.1% leaky). Factors leading to valve failures included residual metal shavings, silicone flash, introduced debris or bedding, and (most common) distortion of the autoclave-rated internal diaphragm and O-ring. Further evaluation revealed that despite normal autoclave conditions of heat, pressure, and steam, an extreme negative vacuum pull caused the valves' internal silicone components (diaphragm and O-ring) to become distorted and water-permeable. Normal flow rate often returned after a 'drying out' period, but components then reabsorbed water while on the animal rack or during subsequent autoclave cycles to revert to a variable flow condition. On the basis of our findings, we recalibrated autoclaves and initiated a preventative maintenance program to mitigate the risk of future valve failure. PMID:22330720

Gonzalez, David M; Graciano, Sandy J; Karlstad, John; Leblanc, Mathias; Clark, Tom; Holmes, Scott; Reuter, Jon D

2011-09-01

382

Failure and Life Cycle Evaluation of Watering Valves  

PubMed Central

Automated watering systems provide a reliable source of ad libitum water to animal cages. Our facility uses an automated water delivery system to support approximately 95% of the housed population (approximately 14,000 mouse cages). Drinking valve failure rates from 2002 through 2006 never exceeded the manufacturer standard of 0.1% total failure, based on monthly cage census and the number of floods. In 2007, we noted an increase in both flooding and cases of clinical dehydration in our mouse population. Using manufacturer's specifications for a water flow rate of 25 to 50 mL/min, we initiated a wide-scale screening of all valves used. During a 4-mo period, approximately 17,000 valves were assessed, of which 2200 failed according to scoring criteria (12.9% overall; 7.2% low flow; 1.6% no flow; 4.1% leaky). Factors leading to valve failures included residual metal shavings, silicone flash, introduced debris or bedding, and (most common) distortion of the autoclave-rated internal diaphragm and O-ring. Further evaluation revealed that despite normal autoclave conditions of heat, pressure, and steam, an extreme negative vacuum pull caused the valves’ internal silicone components (diaphragm and O-ring) to become distorted and water-permeable. Normal flow rate often returned after a ‘drying out’ period, but components then reabsorbed water while on the animal rack or during subsequent autoclave cycles to revert to a variable flow condition. On the basis of our findings, we recalibrated autoclaves and initiated a preventative maintenance program to mitigate the risk of future valve failure.

Gonzalez, David M; Graciano, Sandy J; Karlstad, John; Leblanc, Mathias; Clark, Tom; Holmes, Scott; Reuter, Jon D

2011-01-01

383

Internal combustion engine with rotary valve assembly  

SciTech Connect

This patent describes an internal combustion engine. It includes a block having at least one cylindrical wall surrounding a cylinder, piston means located in the cylinder, means operable to reciprocate the piston means in the cylinder, head means mounted on the block covering the cylinder, the head means having an intake passage for intake gas, an exhaust gas passage for exhaust gas, and a cavity with an inner surface open to the cylinder, and open to the passages, a rotary valve assembly having a valve body located within the cavity, the valve body having a valving combustion chamber and an outer surface spaced from the inner surface of the cavity to enable the valve body to rotate and thereby control the flow of intake gas from the intake passage into the valving combustion chamber of the rotary valve assembly and the cylinder and the flow of exhaust gas out of the valving combustion chamber of the rotary valve assembly and the cylinder to the exhausts gas passage, such flow occurring via the valving combustion chamber in the valve body open to the cylinder and the inner surface of the cavity, first seal means mounted and the inner surface of the cavity, first seal means mounted on the valve body having a hole in alignment with an outer portion of the valving combustion chamber and the inlet and outlet passages.

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

1992-01-21

384

Variable Stars  

NASA Astrophysics Data System (ADS)

It is a tradition to observe variable stars using small telescopes; actually, variable stars are the favorites of small telescopes. What it is needed is those telescopes to be well-equipped (to get good observations), and to be supplied with users (to be productive). The first can be easily achieved; the second, related to the poor job prospects, seems more difficult. Keeping in mind that there is no any Observatory, that could cover the whole sky and that an astronomical event can not be repeated, each individual observation, is very valuable. Especially that of variable stars, where the variability of their luminosity can be caused by many reasons, intrinsic or extrinsic. What is missing -from at least some of the small telescopes spread in whole Europe- is better organization. This means that, besides either some research projects of personal interest, or(/and) students training, some others -being parts of international programs- could also be carried out, focusing to specific objects and goals. The work carried out in the field of variable stars with the use of small telescopes in some European countries, will be presented.

Rovithis-Livaniou, Helen

385

Valve replacement via upper partial sternotomy for quadricuspid aortic valve.  

PubMed

A 52-year-old man was referred to our clinic because of chronic heart failure. A Levine 3/6 diastolic heart murmur was audible at the apex. Chest radiography showed an enlarged left ventricle. Transthoracic echocardiography showed moderately severe aortic regurgitation. Left ventricular end-diastolic/systolic diameter and ejection fraction were 75/59 mm and 41 %, respectively. Preoperative transesophageal 3-dimensional echocardiography revealed a quadricuspid aortic valve whose cusps were of almost equal size. Aortic valve replacement was performed via upper partial sternotomy. PMID:23115003

Sugimura, Yukiharu; Katoh, Masanori; Murakami, Takashi; Kato, Yuji; Toyama, Masaaki

2012-11-01

386

THE VALVE-ACTUATED PULSE COLUMN DESIGN AND OPERATION  

Microsoft Academic Search

A countercurrent extraction column is described which employs timed ;\\u000a solenoid valves and pressurized feeds to provide a pulsing action to disperse the ;\\u000a phases. The steps in the pulsing cycle are independent and thus provide greater ;\\u000a separation of the operating variables than is possible with conventional pulse ;\\u000a columns. The column described is particularly useful as a resesrch

L. L. Burger; L. H. Clark

1951-01-01

387

Resistance trained athletes using or not using anabolic steroids compared to runners: effects on cardiorespiratory variables, body composition, and plasma lipids  

Microsoft Academic Search

OBJECTIVE--To determine whether there is a difference in cardiac size and function as well as in body composition, aerobic capacity, and blood lipids between resistance trained athletes who use anabolic steroids and those who do not, and to compare them to university cross country athletes. METHODS--Four groups of men were evaluated: recreational lifters, n = 11, lifting 10 h.week-1; steroid

R Yeater; C Reed; I Ullrich; A Morise; M Borsch

1996-01-01

388

46 CFR 64.67 - Shutoff valve.  

Code of Federal Regulations, 2012 CFR

...SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.67 Shutoff valve. A shutoff valve may not be locatedâ (a) Between the tank...

2012-10-01

389

Intra-Urethral Prosthetic Sphincter Valve.  

National Technical Information Service (NTIS)

The invention relates to prosthetic urethral valves for controlling urinary continence, and more particularly to a prosthetic urethral valve which is installed totally within a patient's urethra without surgery, and which is controlled by the patient's vo...

S. B. Leighton

1983-01-01

390

Thermal hydraulics of valves for nuclear applications  

SciTech Connect

Thermal-hydraulic aspects of valves used in nuclear power plants are discussed. Emphasis is given to a review of recent work on safety and pressure relief valves, including the presentation of some experimental results describing one- and two-phase flow through such valves. Measurements of internal flow fields are presented. Significant flow separation occurs in both the safety and the pressure relief valves. An experimental study using high-speed photography to determine vaporization sites in safety valves when the flowing medium is initially a compressed liquid is described. A new method of estimating the observed decrease in valve coefficient when choked vapor flow changes to liquid flow is developed. This method also permits the prediction of the observed dependence of the valve coefficient on the receiver pressure in the choked and unchoked flow regimes. The fluid dynamic phenomena that lead to valve disk vibrations are discussed.

Sallet, D.W.

1984-11-01

391

Multi-Ported Diverter Valve Assembly.  

National Technical Information Service (NTIS)

The metallic housing of a diverter valve assembly has a plurality of threaded positioned inserts therein through which different port passage paths are established with a multi-ported ball valve element angularly displace able inside the housing while sea...

J. F. Korczynski P. D. Conroy

1997-01-01

392

Bistable diverter valve in microfluidics  

NASA Astrophysics Data System (ADS)

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

Tesa?, V.; Bandalusena, H. C. H.

2011-05-01

393

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

394

Full bore sampler valve apparatus  

SciTech Connect

In accordance with an illustrative embodiment of the present invention, a full-bore sampler and safety valve apparatus includes a housing having an actuator mandrel slidably arranged therein, axially spaced normally open ball valve elements mounted on the mandrel assembly and cooperable with fixed eccentric pins on the housing for simultaneously closing a flow passage extending through the housing when the mandrel assembly is shifted from one axial position to another, a hydraulically operable piston on the mandrel assembly normally subject to balanced pressures, and means responsive to a predetermined pressure of fluids in the well annulus for exposing the hydraulically operable means to well pressure to cause shifting of the actuator mandrel assembly and simultaneous closing of the ball valve elements.

Meek, D. E.; Upchurch, J. M.

1985-11-19

395

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

396

Tricuspid valve replacement with the St. Jude Medical valve: 19 years of experience  

Microsoft Academic Search

Objective: The choice of the valve substitute in the tricuspid position remains controversial. A St. Jude Medical valve is a choice of valve substitute and its lower thrombogenicity and excellent hemodynamic performance have been reported even in the tricuspid position. However, little is known of the long-term durability of the St. Jude Medical valve in the tricuspid position. Our long-term

Hiroshi Kawano; Takeshi Oda; Shuji Fukunaga; Eiki Tayama; Takemi Kawara; Atsushige Oryoji; Shigeaki Aoyagi

2000-01-01

397

Kamyr PD Series Full-Borne Ball Valve METC SOA Test Valve No. A-17 state-of-the-art lockhopper valve-testing and development project  

Microsoft Academic Search

The Kamyr Ball Valve, METC SOA Test Valve No. A-17, accumulated 640 valve cycles in the Valve Static Test Unit and over 16,900 valve cycles in the Valve Dynamic Test Unit. During dynamic testing (with minus 8 mesh and 5\\/16'' x 1\\/8'' limestone), the stem packing was replaced twice and the valve was disassembled once to remove compacted fines from

J. F. Gardner; R. C. Hall; R. G. Hornbeck; R. A. Griffith; T. M. Nutter; T. M. Yost; T. Vandergrift; T. R. Gayheart; D. L. Armstrong

1981-01-01

398

Resistance trained athletes using or not using anabolic steroids compared to runners: effects on cardiorespiratory variables, body composition, and plasma lipids.  

PubMed Central

OBJECTIVE--To determine whether there is a difference in cardiac size and function as well as in body composition, aerobic capacity, and blood lipids between resistance trained athletes who use anabolic steroids and those who do not, and to compare them to university cross country athletes. METHODS--Four groups of men were evaluated: recreational lifters, n = 11, lifting < 10 h.week-1; heavy lifters, n = 16, lifting > 10 h.week-1; steroid users, n = 8, same as heavy lifters and used steroids; runners, n = 8, university track members. Echocardiograms, body composition (hydrostatic weighing), maximum oxygen consumption (Vo2), and lipids were studied. RESULTS--As expected, Vo2 (ml.kg-1.min-1), was greatest in the runners, with no difference among the lifting groups. High density lipoprotein cholesterol in the steroid user group was lower than in heavy lifters or runners. Left ventricular internal diastolic dimension was similar among the groups. The left ventricular mass index of the steroid user group was significantly greater than recreational lifters, at 161 v 103. There was no difference among heavy lifters (127), runners (124), and steroid users. There was no compromise in diastolic function in any group. There were no differences among groups in resting or exercise blood pressure. CONCLUSIONS--Resistance training in the absence of steroid use results in the same positive effects on cardiac dimensions, diastolic function, and blood lipids as aerobic training.

Yeater, R; Reed, C; Ullrich, I; Morise, A; Borsch, M

1996-01-01

399

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

SciTech Connect

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

Ng, R.; Kwon, D.M.

1998-12-31

400

An integrated liquid mixer\\/valve  

Microsoft Academic Search

We present an integrated liquid mixer\\/valve to be used for sample preparation for bioscience analysis systems. The mixer\\/valve is a glass-silicon bonded structure with a wafer-bonded cantilever-plate flapper valve and deep reactive-ion etched ports. It is passively pressure actuated and is distinguished by the fact that it can perform both a mixing and valving function simultaneously to mix two liquids

Joel Voldman; Martha L. Gray; Martin A. Schmidt

2000-01-01

401

Valve failure problems in LWR power plants  

Microsoft Academic Search

A study of the causes of and solutions for recurrent valve failures causing reactor shutdowns has been performed. Frequency and root causes of the valve failures were identified from licensee event reports and meetings with utility, nuclear steam-system supplier, and valve manufacturer personnel. Valves are responsible for approx. 19% of light-water-reactor (LWR) power-plant shutdowns, more than any other type of

R. J. Reyer; J. W. Riddington

1981-01-01

402

Internally piloted reversing valve for heat pump  

Microsoft Academic Search

An internally piloted reversing refrigerant valve for selectively porting fluid from a compressor into an air-conditioning system doubling as heat pump through a five-ported valve of which ports one, two, three and four are employed with air-conditioning system when valve is in a first position, while when the position of valve is changed to a second reversed position, ports one,

Pauliukonis

1979-01-01

403

Perceived importance as a mediator of the relationship between training assignment and training motivation  

Microsoft Academic Search

In this study, we examined whether employees’ perceived importance of the training program would be one variable that mediates the relationship between training assignment and training motivation. Data were collected from 184 employees belonging to 18 banks who attended government-sponsored training programs in Northern Taiwan. Participants were asked to complete two questionnaires: one at the beginning of the training program

Wei-Chi Tsai; Wei-Tao Tai

2003-01-01

404

TWO-WAY FREEZE VALVE  

DOEpatents

A valve for closing off the flow of radioactive and corrosive gases and liquids or mixtures thereof and forming a leak tight barrier is described. This valve has no mechanical moving parts which would require design to close tolerances and retention of the usual seal tighthess. Instead, there is provided a cavity in which a fusible metal is contained. Heating and cooling are provided to exercise control over the state of the metal. Baffle chambers are utilized to separate the molten fusible metal from the gas or liquid which is being passed through and return the molten metal to its cavity.

Lantz, K.D.; Clark, P.M.

1960-01-01

405

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

406

[Early bioprosthetic mitral valve thrombosis].  

PubMed

We present a case of a 70 year-old woman operated due to severe mitral regurgitation. Early after surgery transthoracic echocardiography revealed the decreased effective orifice area of the implanted bioprosthetic valve and the stenotic features of transvalvular flow. Transesophageal echocardiography (TEE) disclosed a thrombotic cause of heterograft dysfunction. Due to the clinical deterioration and the unclear cause of prosthesis stenosis, the patient was reoperated. Intra-operatively bioprosthetic mitral valve thrombosis was confirmed. Precipitating factors of this rare complication including cardiac device related infective endocarditis (CDRIE) and the diagnostic applicability of TEE in this clinical scenario are discussed. PMID:22427084

Tkaczyszyn, Micha?; Olbrycht, Tomasz; Kustrzycka Kratochwil, Dorota; Sokolski, Mateusz; Sukiennik Kujawa, Ma?gorzata; Skiba, Jacek; Gemel, Marek; Banasiak, Waldemar; Jankowska, Ewa A; Ponikowski, Piotr

2012-01-01

407

Fast variable-amplitude cold gas thruster  

Microsoft Academic Search

A fast response variable amplitude cold gas thruster is described. A laboratory prototype comprised of a piezoelectric stack and an associated microprocessor-based programmable dc power source, a low-loss mechanical displacement amplifier, a high-pressure spring-loaded axial valve, an integral high-pressure valve seat; an expansion nozzle, and a high-pressure gas supply were constructed and tested. The device is designed to operate as

William C. Stone

1995-01-01

408

Balloon valuloplasty prior to transcatheter valve-in-valve implantation in a degenerated Mitroflow aortic bioprosthesis.  

PubMed

Transcatheter valve-in-valve implantation is an emerging treatment option for high-risk patients with failing aortic bioprostheses. The presence of the prosthesis stents is thought to prevent coronary artery obstruction, a known complication of transcatheter aortic valve implantation in the native aortic valve. The Sorin Mitroflow aortic bioprosthesis (Sorin Group, Saluggia, Italy) has a particular design in that the pericardial leaflets are mounted outside the valve stent. As a consequence, the pericardial leaflets of this prosthesis may be displaced well away from the stents during the deployment of transcatheter valves. This might explain why both the cases of coronary occlusion following valve-in-valve implantation reported to date occurred in patients with a malfunctioning Mitroflow bioprosthesis. We describe a patient with a malfunctioning 25 mm Mitroflow bioprosthesis successfully treated by percutaneous transcatheter valve-in-valve implantation, and discuss the role that balloon aortic valvuloplasty plays in the performance of this delicate procedure. PMID:22744728

Cerillo, Alfredo Giuseppe; Berti, Sergio; Glauber, Mattia

2012-07-23

409

Impact wear testing of diamond-like carbon films for engine valve-tappet surfaces  

Microsoft Academic Search

There is a strong drive to reduce the energy losses from automotive engines in order to improve fuel economy and reduce emissions of pollutants. The demands of reducing engine losses are pushing engine manufacturers to consider using technologies such as diamond-like carbon (DLC) coatings to give enhanced wear protection of components and provide low friction operation. Valve-train component interactions are

S. D. A. Lawes; S. V. Hainsworth; M. E. Fitzpatrick

2010-01-01

410

Pressure relief valve/safety relief valve testing.  

National Technical Information Service (NTIS)

Pressure vessels and piping systems are protected form overpressurization by pressure relief valves. These safety features are required to be tested-inspected on some periodic basis and, in most cases witnessed by a third party inspector. As a result nonc...

W. A. Murray E. R. Hamm J. R. Barber

1994-01-01

411

Pressure relief valve\\/safety relief valve testing  

Microsoft Academic Search

Pressure vessels and piping systems are protected form overpressurization by pressure relief valves. These safety features are required to be tested-inspected on some periodic basis and, in most cases witnessed by a third party inspector. As a result nonconformances found by third parties Westinghouse Hanford Company initiated a task team to develop a pressure safety program. This paper reveals their

W. A. Murray; E. R. Hamm; J. R. Barber

1994-01-01

412

Hydraulic Valve Erosion Investigation -- 727 Elevator Feel Computer Valve.  

National Technical Information Service (NTIS)

The report covers progress made in one portion of the investigation into the hydraulic control valve erosion problem encountered on 727 and 737 airplanes. The portion of work presented in this report includes testing with the old design (LTV P/N 401-60547...

I. A. Eacrett

1968-01-01

413

Lock Culvert Valves; Hydraulic Design Considerations.  

National Technical Information Service (NTIS)

This report presents a review of design guidance and hydraulic parameters associated with lock culvert valves. Many locks are beyond their design life, and the filling- and emptying-culvert valves are being replaced to keep the lock in service. Valve sele...

E. A. Hammack J. J. Hite R. L. Stockstill

2011-01-01

414

Valve fugitive emissions: The challenge ahead  

Microsoft Academic Search

The problem of controlling fugitive emissions from valves, particularly from stem seals, is acknowledged by the sealing industry, valve manufacturers and end users alike as one of the most important technical challenges facing them now that the replacement of asbestos is seals and gaskets reaches completion. The introduction of a new ISO standard on fugitive emissions from valves, due for

Suresh Kakaiya

1999-01-01

415

Needle valve tap. (Robinet a pointeau).  

National Technical Information Service (NTIS)

The invention involves a needle valve tap in which the axial movement of the needle valve is controlled by rotation of a rod having two threads, one screwing axially into the needle valve and the other screwing into the tap body, the first of these two th...

1990-01-01

416

Whitey SCHE Gauge and Root Valves  

SciTech Connect

These valves are 1/2 inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as isolation valves for pressure instrumentation in the SCHe System between the helium bottle supply manifolds and safety class helium pressure instrumentation, and in lower pressure SCHe supply line.

MISKA, C.R.

2000-09-03

417

Whitey SCHE Gauge and Root Valves  

SciTech Connect

These valves are 1/2 inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as isolation valves for pressure instrumentation in the SCHe System between the helium bottle supply manifolds and safety class helium pressure instrumentation, and in lower pressure SCHe supply line.

VAN KATWIJK, C.

2000-06-21

418

The Assessment of Prosthetic Valve Function  

Microsoft Academic Search

\\u000a a. Mechanical prosthetic valves: i. Composition: Titanium or silicon derived with a sewing ring, Durability: 25–30 years Risk\\u000a of thromboembolism: 0.1–5.7 patient-years in mitral valve position. Obligatory normal regurgitation more common than tissue\\u000a valves.

Mengistu Simegn; Anupama Kottam; Luis Afonso

419

A Journey through Heart Valve Surgery  

Microsoft Academic Search

Valve replacement with cardiopulmonary bypass is currently the treatment of choice for symptomatic aortic, pulmonic, tricuspid, and mitral stenosis and regurgitation but carries a significant risk of morbidity and mortality, particularly in patients with comorbidities. Medical advances of the 21 st century have made heart and valve surgeries less complicated reducing the complication rate. Today heart and valve surgeries are

Mallory Piaschyk; Alaina Cyr; Amy M. Wetzel; Ani Tan; Cecilia Mora; Doug W. Long; Laarni Mendoza; Marivic A. Dela Cruz; Rebecca Gilliam; Sheila Rolanda G. Bolanos; Serena Stansbury; Erika Diniz-Borkar; Charmaine Christiansen Moore; Lea Johanna Hyvarinen; Catherine Fusilier; Natalie Culpepper; Suzanne Matson

420

Line Fluid Actuated Valve Development Program.  

National Technical Information Service (NTIS)

The feasibility of a line-fluid actuated valve design for potential application as a propellant-control valve on the space shuttle was examined. Design and analysis studies of two prototype valve units were conducted and demonstrated performance is report...

R. A. Lynch

1975-01-01

421

Lambl's excrescences of the mitral valve  

PubMed Central

A young male patient, just recovered from a recent transient ischaemic attack, was operated on for mitral valve insufficiency due to suspected endocarditis. Multiple wear-and-tear lesions were found at the line of closure of the mitral valve, which appeared to be Lambl's excrescences. The valve was replaced. ImagesFigure 1Figure 2

Bruinsma, G.J. Brandon Bravo; Leicher, F.G.

2002-01-01

422

VALVES FOR CONTROLLING HIGH-TEMPERATURE FLUIDS  

Microsoft Academic Search

A valve for high-temperature liquid (sodium) with a selfsealing leak-; proof gland of (a plurality of) O-ring seals arranged as an insert over the ; spindle on a sleeve-like extension of the valve body. The extension and the ; spindle are of such length that combined with fins around the extension, a ; temperature drop is caused between the valve

1957-01-01

423

Reoperation for Prosthetic Heart Valve Dysfunction  

PubMed Central

Between September 1968 and October 1987, 152 patients (66 males and 86 females; age range, 15 to 79 years) underwent 1 or more reoperations (total, 179) for prosthetic valve dysfunction at our hospital. In this report, we present material and statistics reflecting our experience with the last reoperation in these 152 patients. The procedures involved the mitral valve in 93 patients, the aortic valve in 38 patients, double valves (aortic and mitral) in 19, and the tricuspid valve in 2. Sixty-five patients were operated on for mechanical valve dysfunction, and 87 for tissue valve dysfunction. The modes of valve dysfunction that indicated surgery were primary valve failure (85 patients), valvular thrombosis and valve-related thromboembolic episodes (27 patients), paravalvular leak (25 patients), prosthetic valve endocarditis (14 patients), and hemolysis (1 patient). Three patients were in New York Heart Association functional Class II, 77 were in Class III, and 61 were in Class IV; the remaining 11 cases were emergencies. The 30-day operative mortality was 14.5%, the 5-year survival was 75%, and the 10-year survival was 63%. The preoperative functional class and the mode of valve dysfunction significantly influenced both early and late mortality. (Texas Heart Institute Journal 1990;17:106-11)

Masri, Zahi; Girardet, Roland; Attum, Abdulla; Barbie, Ronald; Yared, Isam; Lansing, Allan

1990-01-01

424

Risk Factors of Prosthetic Valve Endocarditis  

Microsoft Academic Search

Background. Prosthetic valve endocarditis is an impor- tant cause of the morbidity and mortality associated with heart valve replacement surgery. The objective of this study was to assess risk factors of prosthetic valve endocarditis related to patients, perioperative events, and postoperative complications. Methods. This was a retrospective case-control study conducted in a tertiary care hospital in Santander, Spain, from January

M. Carmen Fariñas; Alberto Pérez-Vázquez; Concepción Fariñas-Álvarez; J. Daniel García-Palomo; José M. Bernal; José M. Revuelta; Jesús González-Macías; Medicina Familiar

425

Functional analysis of bioprosthetic heart valves  

Microsoft Academic Search

Glutaraldehyde-treated bovine pericardium is used successfully as bioprosthetic material in the manufacturing of heart valves leaflets. The mechanical properties of bovine pericardial aortic valve leaflets seem to influence its mechanical behaviour and the failure mechanisms. In this study the effect of orthotropy on tricuspid bioprosthetic aortic valve was analysed, using a three-dimensional finite element model, during the entire cardiac cycle.

G. Arcidiacono; A. Corvi; T. Severi

2005-01-01

426

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

427

Whitey SCHE Gauge and Root Valves  

SciTech Connect

These valves are 1/2 inch ball valves fabricated of 316 stainless steel. Packing is TFE (standard). They are used as isolation valves for pressure instrumentation in the SCHa System between the helium bottle supply manifolds and safety class helium pressure instrumentation, and in lower pressure SCHa supply line.

MISKA, C.R.

2000-09-11

428

Minimizing energy losses in control valves  

Microsoft Academic Search

The pulp and paper industry uses massive amounts of energy, but it could reduce its electricity consumption by about 2,000 MW worldwide by simply optimizing the pumping of process liquids. Wasted pumping power can be significantly reduced by sizing pumps and control valves more accurately, and by using new methods of pump and valve selection. Combining the improved control valve's

I. Niemela; J. Pyotsia

1994-01-01

429

Solve valve noise and cavitation problems  

Microsoft Academic Search

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

1997-01-01

430

Consider poppet valves for compressor retrofits  

SciTech Connect

Designing a reliable compressor valve is challenging enough, but the design must also impose minimum flow resistance, form an effective seal at the proper time and ensure that fixed clearance is appropriate for service conditions. Some of these parameters conflict, and this results in a variety of valve designs. These designs are reviewed, and experience with modern poppet-type valves is presented.

Bunn, J.

1988-02-01

431

Aerodynamic Characteristics of Tracheostomy Speaking Valves.  

ERIC Educational Resources Information Center

Pressure-flow characteristics were determined for four different one-way valves (Kisner, Montgomery, Olympic, and Passy-Muir) used for speech production in tracheotomy patients. Results indicated significant differences in resistance among the valves, with the resistance of one valve substantially greater than that of the normal upper airways.…

Fornataro-Clerici, Lisa; Zajac, David J.

1993-01-01

432

14 CFR 27.995 - Fuel valves.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Fuel valves. 27.995 Section 27.995 Aeronautics...Fuel System Components § 27.995 Fuel valves. (a) There must be a positive, quick-acting valve to shut off fuel to each engine...

2013-01-01

433

14 CFR 25.995 - Fuel valves.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Fuel valves. 25.995 Section 25.995 Aeronautics...System Components § 25.995 Fuel valves. In addition to the requirements of § 25.1189 for shutoff means, each fuel valve mustâ (a) [Reserved]...

2013-01-01

434

14 CFR 25.1025 - Oil valves.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Oil valves. 25.1025 Section 25.1025 Aeronautics...Powerplant Oil System § 25.1025 Oil valves. (a) Each oil shutoff must meet the...propeller feathering. (c) Each oil valve must have positive stops or suitable...

2013-01-01

435

14 CFR 29.1025 - Oil valves.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Oil valves. 29.1025 Section 29.1025 Aeronautics...Powerplant Oil System § 29.1025 Oil valves. (a) Each oil shutoff must meet the...prevent autorotation. (c) Each oil valve must have positive stops or suitable...

2013-01-01

436

14 CFR 125.133 - Fuel valves.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Fuel valves. 125.133 Section 125.133 Aeronautics and...Special Airworthiness Requirements § 125.133 Fuel valves. Each fuel valve mustâ (a) Comply with § 125.155; (b)...

2013-01-01

437

14 CFR 121.235 - Fuel valves.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Fuel valves. 121.235 Section 121.235 Aeronautics and...Special Airworthiness Requirements § 121.235 Fuel valves. Each fuel valve mustâ (a) Comply with § 121.257; (b)...

2013-01-01

438

14 CFR 29.995 - Fuel valves.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Fuel valves. 29.995 Section 29.995 Aeronautics...System Components § 29.995 Fuel valves. In addition to meeting the requirements of § 29.1189, each fuel valve mustâ (a) [Reserved]...

2013-01-01

439

49 CFR 195.116 - Valves.  

Code of Federal Regulations, 2012 CFR

...Transportation 3 2012-10-01 2012-10-01 false Valves. 195.116 Section 195.116 Transportation...LIQUIDS BY PIPELINE Design Requirements § 195.116 Valves. Each valve installed in a pipeline system must comply with...

2012-10-01

440

Aortic valve-sparing procedure with cusp elongation and free edge reinforcement for bicuspid aortic valve.  

PubMed

Aortic valve-sparing procedures demonstrate excellent valvular function at midterm. Recently authors have reported acceptable early results with aortic valve-sparing procedures on patients with regurgitant bicuspid valves. We report the case of a novel procedure to preserve bicuspid valves with a calcified raphe and root dilatation. This procedure includes raphe excision, pericardial patch elongation, free edge leaflet reinforcement, and a root reimplantation valve-sparing procedure. PMID:15797089

Dagenais, Francois; Bauset, Richard; Mathieu, Patrick

2005-04-01

441

Midterm surgical results after valve replacement with the carbomedics valve prosthesis  

Microsoft Academic Search

We present herein a review of 95 patients who underwent valve replacement with the CarboMedics (CM) valve prosthesis between April 1990 and December 1992. The operative mortality for the entire group was 4.2%: 0% following aortic valve replacement (AVR), 2.7% following mitral valve replacement (MVR), and 12.5% following double valve replacement (DVR). All patients were prescribed warfarin and bucolome for

Tomio Abe; Kiyohumi Morishita; Masaru Tsukamoto; Toshiaki Tanaka; Sakuzo Komatsu

1995-01-01

442

Dynamic Simulations and an Adaptive Valve Timing Control for a Camless Engine Valve Actuator  

Microsoft Academic Search

Camless Engine Valve Actuation (CEVA) technologies have been known for improving fuel efficiency, enhancing power output, and reducing emissions of Internal Combustion(IC) engine. Electro-Hydraulic valve actuators are used to eliminate the camshaft of an existing Internal Combustion(IC) engine and to control the valve timing of intake and exhaust valves, valve duration independently. This paper presents a research activity like hydraulic

Kanghyun Nam

443

Control of engines with fully variable valvetrains  

Microsoft Academic Search

To improve performance, fuel economy, and emissions of automotive engines, automakers have introduced a number of devices intended to vary a previously fixed engine parameter with operating condition. Such devices include variable cam timing and valve lift, variable compression ratio, intake manifold tuning, etc. Combining these devices in an engine promises improved fuel economy, but raises the issue of scheduling

Mrdjan Jankovic; Stephen Magner

2005-01-01

444

Angiotensin receptor blockers are associated with reduced fibrosis and interleukin-6 expression in calcific aortic valve disease.  

PubMed

Background: Calcific aortic valve disease (CAVD) is a chronic disorder characterized by the mineralization of the aortic valve and involving fibrosis. Objectives: In this work we sought to determine if the fibrotic component of the remodeling process of CAVD was related to the use of angiotensin-converting enzyme inhibitors (ACEi) and/or angiotensin receptor blockers (ARBs). Methods: In 477 patients with CAVD, the aortic valve was examined by histology. A semiquantitative score of fibrosis was generated and associations with clinical/cardiometabolic variables examined. In a subset of 103 patients the aortic valve was available to study the infiltration by inflammatory cells and expression of interleukin-6 (IL-6) by quantitative real-time PCR. Results: The fibrosis score of the aortic valve was independently related to the hemodynamic severity of CAVD measured by echocardiography. The fibrotic score of the aortic valve was also related to the expression of IL-6. The use of ARBs but not of ACEi was associated with a lower fibrosis score of the aortic valve even after correction for covariates. In addition, patients under ARBs had lower aortic valve inflammation and expression of IL-6. Conclusions: These findings suggest that ARBs may alter the fibrotic process of the aortic valve in CAVD, possibly by lowering tissue inflammation. PMID:23969418

Côté, Nancy; Mahmut, Ablajan; Fournier, Dominique; Boulanger, Marie-Chloé; Couture, Christian; Després, Jean-Pierre; Trahan, Sylvain; Bossé, Yohan; Pagé, Sylvain; Pibarot, Philippe; Mathieu, Patrick

2013-08-21

445

Dynamic shape modeling of the mitral valve from real-time 3D ultrasound images using continuous medial representation  

NASA Astrophysics Data System (ADS)

Purpose: Patient-specific shape analysis of the mitral valve from real-time 3D ultrasound (rt-3DUS) has broad application to the assessment and surgical treatment of mitral valve disease. Our goal is to demonstrate that continuous medial representation (cm-rep) is an accurate valve shape representation that can be used for statistical shape modeling over the cardiac cycle from rt-3DUS images. Methods: Transesophageal rt-3DUS data acquired from 15 subjects with a range of mitral valve pathology were analyzed. User-initialized segmentation with level sets and symmetric diffeomorphic normalization delineated the mitral leaflets at each time point in the rt-3DUS data series. A deformable cm-rep was fitted to each segmented image of the mitral leaflets in the time series, producing a 4D parametric representation of valve shape in a single cardiac cycle. Model fitting accuracy was evaluated by the Dice overlap, and shape interpolation and principal component analysis (PCA) of 4D valve shape were performed. Results: Of the 289 3D images analyzed, the average Dice overlap between each fitted cm-rep and its target segmentation was 0.880+/-0.018 (max=0.912, min=0.819). The results of PCA represented variability in valve morphology and localized leaflet thickness across subjects. Conclusion: Deformable medial modeling accurately captures valve geometry in rt-3DUS images over the entire cardiac cycle and enables statistical shape analysis of the mitral valve.

Pouch, Alison M.; Yushkevich, Paul A.; Jackson, Benjamin M.; Gorman, Joseph H., III; Gorman, Robert C.; Sehgal, Chandra M.

2012-02-01

446

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.

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

1967-01-01

447

Advanced Microbial Check Valve Development.  

National Technical Information Service (NTIS)

A flight certified assembly identified as a Microbial Check Valve (MCV) was developed and tested. The MCV is a canister packed with an iodinated anionic exchange resin. The device is used to destroy organisms in a water stream as the water passes through ...

G. V. Colombo D. R. Greenley

1980-01-01

448

Electromagnetically actuated ball valve micropumps  

Microsoft Academic Search

We present two types of oscillating diaphragm micropumps configured with passive ball valves and using electromagnetic actuation. One type is made out of poly(methyl methacrylate) (PMMA), while the other one is made out of borosilicate glass. Both were produced using the powder blasting microfabrication method. The pumping resonant frequency was measured to be within the range of 20-30 Hz for

Christophe Yamahata; Frédéric Lacharme; Jan Matter; Silvan Schnydrig; Yves Burri; Martin A. M. Gijs

2005-01-01

449

Effects of training framing, general self-efficacy and training motivation on trainees' training effectiveness  

Microsoft Academic Search

Purpose – The purpose of this paper is to examine the effects of training framing from supervisors on trainee self-efficacy and training motivation, and further test how these variables subsequently influence overall training effectiveness. Design\\/methodology\\/approach – The design of the study includes longitudinal, self-report and objective measures. Data were collected from 126 employees who entered a training program aiming at

Wei-Tao Tai

2006-01-01

450

Valve assembly having remotely replaceable bearings  

DOEpatents

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

Johnson, Evan R. (San Diego, CA); Tanner, David E. (Poway, CA)

1980-01-01

451

The Changing Pattern of Aortic Valve Repair  

PubMed Central

The changes and improvements in the surgical treatment of aortic valve disease in 296 patients, who were operated on between 1953 and 1965, are illustrated and discussed in general terms. Several of the early techniques, such as transventricular dilation, insertion of a homograft aortic valve in the descending thoracic aorta, fabric replacement of one cusp or the entire valve, and ice-chip arrest of the heart, are now obsolete. Total replacement with a ball-valve prosthesis or an aortic valve homograft while the coronary arteries are perfused with blood is the currently popular technique. The results of a hemodynamic follow-up study two years after surgery are also included.

Baird, Ronald J.; Lipton, Irving H.

1965-01-01

452

Valve operating mechanism for internal combustion engine  

SciTech Connect

This patent describes a valve operating mechanism for operating valves of a particular cylinder of an internal combustion engine, comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine and having at least one cam; cam followers, one of which slidably engages with the cam for selectively operating the valves according to a cam profile of the cam; and means for selectively interconnecting and disconnecting the cam followers to operate the valves differently in different speed ranges of the internal combustion engine, the speed ranges including a range in which all of the valves remain inoperative.

Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

1988-12-13

453

Valve operating mechanism for internal combustion engine  

SciTech Connect

A valve operating mechanism for operating a single valve of a particular cylinder of an internal combustion engine is described comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine; a plurality of cams on the camshaft with each of the cams bearing a different cam profile; a plurality of cam followers, each of which slidably engages one of the cams for selectively operating the valve according to the profile of the selected cam and one of which engages the valve; and means for selectively interconnecting and disconnecting the respective cam followers to operate the valve differently in different speed ranges of the internal combustion engine.

Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

1988-12-27

454

Sizing sliding gate valves for steam service  

SciTech Connect

Sliding gate valves have been used in thousands of applications during the past 40 yr. While steam control is a common application for these valves, thy are also used to control other gases and liquids. The sliding gate design provides straight-through flow, which minimizes turbulence, vibration, and noise. Seats are self-cleaning and self-lapping to provide a tight, long-lasting shutoff. A correctly sized valve is essential for accurate control. Valve size should be determined by service and system requirements, not by the size of the existing pipeline. Sizing a valve on the basis of pipeline size usually results in an oversized valve and poor control. Generally, regulator size is smaller than pipe size. Whenever complete information is known (inlet pressure, outlet pressure, or pressure drop, and required flow), determine the valve flow coefficient (C{sub v}) using the equations in ANSI/ISA S75.01 or a flow sizing chart. Tables of values for various types of valves are available from manufacturers. However, when complete system requirements are not known, valve oversizing is prevented by determining the design capacity of piping downstream from the valve. The valve should not be sized to pass more flow than the maximum amount the pipe can handle at a reasonable velocity. An example calculation is given.

Bollinger, R. [Jordan Value, Cincinnati, OH (United States)

1995-11-06

455

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

2009-08-07

456

Degenerative mitral valve regurgitation: best practice revolution  

PubMed Central

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

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

2010-01-01

457

Training attentional control in older adults  

Microsoft Academic Search

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

Anna MacKay-Brandt

2011-01-01

458

Internal combustion engine with rotary valve assembly  

SciTech Connect

This patent describes a rotary valve assembly for an internal combustion engine. It comprises a housing having a bore, a gas inlet passage and a gas outlet passage open to the bore, a continuous cylindrical sleeve means located in the bore, the sleeve means having an inner surface and ports aligned with the passages, rotatable means located within the sleeve means for controlling the flow of gas into and out of the assembly, the rotatable valving means having a valving chamber open to means to accommodate a gas and the inner surface of the sleeve means, the rotatable valving means having a valve body, spark generating means mounted on the body in communication with the valving combustion chamber operable to ignite fuel therein, the valving chamber having an inner portion located in the valve body, the valve body having an outer surface spaced from the inner surface of the sleeve means, segment seal means mounted on the valve body for rotation therewith, the segment seal means being engagable with the inner surface of the sleeve means, the segment seal means having a hole aligned with an outer portion of the valving chamber, cooperating pin and slot means on the segment seal means and valve body and allow the segment seal means to move about an axis generally parallel to the inner surface of the sleeve means, biasing means located between the valve body and seal means to hold the seal means into engagement with the inner surface of the sleeve means, and means operable to rotate the rotatable having means whereby the valving passage sequentially moves into alignment with the ports allowing gas to flow in the inlet and outlet gas passages.

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

1991-03-19

459

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

PubMed

A central venous catheter (CVC) is inserted for measurement of haemodynamic variables, delivery of nutritional supplements and drugs and access for haemodialysis and haemofiltration. Catheterization and maintenance are common practices and there is more to the technique than routine placement as evident when a procedure-related complication occurs. More than 15% of the patients who receive CVC placement have some complications and infectious endocarditis involving the tricuspid valve is a rare and serious complication with high morbidity and mortality. Overenthusiastic and deep insertion of the guide wire and forceful injection through the CVC may lead to injury of the tricuspid valve and predispose to bacterial deposition and endocarditis. We report a case of tricuspid valve endocarditis, probably secondary to injury of the anterior tricuspid leaflet by the guide wire or the CVC that required open heart surgery with vegetectomy and repair of the tricuspid valve. PMID:24163455

Kale, Suresh Babu; Raghavan, Jagannathan

2013-07-01

460

Outcomes of prenatally diagnosed tetralogy of Fallot: Implications for valve-sparing repair versus transannular patch  

PubMed Central

OBJECTIVES: To assess outcomes of prenatally diagnosed tetralogy of Fallot and determine factors associated with the choice to undergo a valve-sparing repair versus transannular patch, and the use of prostaglandins at birth. METHODS: All cases at The Hospital for Sick Children (Toronto, Ontario) with a fetal diagnosis of tetralogy of Fallot from 1998 to 2006, were reviewed for demographic and fetal echocardiographic data to determine factors associated with the valve-sparing repair and need for perinatal support. RESULTS: Sixty-four fetuses met inclusion criteria (median gestational age 22 weeks) with 47 live births. Twenty-six underwent valve-sparing repair (median age 5.7 months) and 14 underwent transannular patch repair (median age 4.5 months). There were seven deaths before surgery and one post-transannular patch repair. One patient required a transannular patch repair after the initial valve-sparing repair. Twelve of 29 (41%) patients received prostaglandins at birth. Type of surgical repair, use of prostaglandins and postnatal death were among the outcomes investigated. The mean pulmonary valve (PV) z-score was ?3.0±2.0 and the mean PV/aortic valve (AoV) ratio was 0.65±0.10. Lower PV z-score (P=0.04), smaller PV/AoV ratio (P=0.04) and the presence of nonantegrade arterial duct flow (P=0.02) were associated with prostaglandin use. A higher PV/AoV ratio was associated with valve-sparing repair (P=0.04). Fetal z-scores of the PV, AoV and right pulmonary artery at 29 to 32 weeks gestational age correlated with respective postnatal z-scores (P=0.01). CONCLUSION: Fetal echocardiographic variables were associated with the use of prostaglandins and valve-sparing repair in fetuses with tetralogy of Fallot, and at 29 weeks, correlated with postnatal valve diameters.

Hirji, Alim; Bernasconi, Alessandra; McCrindle, Brian W; Dunn, Elizabeth; Gurofsky, Rebecca; Manlhiot, Cedric; Miner, Steven ES; Kingdom, John CP; Jaeggi, Edgar T; Van Arsdell, Glen; Nield, Lynne E

2010-01-01

461

A New Hemostasis Valve for Neuroendovascular Procedures  

PubMed Central

Summary A hemostasis valve is routinely used in neuroendovascular procedures to decrease the risk of thromboembolism1,2. Recently, a new hemostasis valve that is designed to minimize blood loss has been introduced. We report our initial experience in using this new hemostasis valve. In neuroendovascular procedures, a hemostasis valve is commonly used for continuous irrigation of guide and microcatheters to decrease the risk of thromboembolism1,2,3. A conventional hemostasis valve has a rotating seal at the end, which is turned open or closed each time a wire or microcatheter/guidewire is introduced or extracted. Often this results in significant back bleeding. When a rotating seal is adjusted suboptimally during a wire or microcatheter manipulation, leakage of pressurized saline from the end of a hemostasis valve results in stagnation of blood within a guiding catheter, which becomes a potential source of emboli during a procedure. The Guardian Haemostasis Valve (Zerusa Limited, Galway, Ireland) is a new hemostasis valve that is designed to minimize blood loss during interventional procedures by minimizing the opening time of the valve during wire or microcatheter insertion. A continuous sealing mechanism during wire or microcatheter positioning minimizes blood loss and stagnation of blood within the guide catheter. We report our initial experience with the Guardian hemostasis valve.

Namba, K.; Song, J.K.; Niimi, Y.; Heran, N.S.; Berenstein, A.

2007-01-01

462

Development of improved boiler startup valves  

SciTech Connect

Existing fossil fuel power plants are increasingly used for cyclic duty. Future coal fired power plants will probably have supercritical, sliding pressure boilers, designed for daily load cycling. This requires a startup valve system, which can perform reliably during daily load cycling. For this reason EPRI initiated the design of an improved valve under Project RP1403 intended for advanced supercritical boilers designed for daily load cycling. The following failure modes were identified: cracking of valve bodies due to thermal stresses, clamping of foreign particles on valve seats, erosion of valve internals, leakage of plunger packings and gaskets and actuator failures. Improved actuators are already commercially available. In a separate project EPRI is developing a cast version of the high-strength 9 chrome steel, P-91. This will allow valve bodies with thinner walls which will reduce thermal stresses. The other three areas of concern were addressed in this study, by comparing the performance of subscale valve parts of different design. Thus a conceptual design of an improved angle valve was developed. It is expected that the valve will also be suitable for retrofits at power plants, where switching from base load to cyclic duty requires upgrading of the startup valve system. 53 figs., 12 tabs.

Wolowodivk, W.; Kajigaya, I.; Yagi, Y.

1989-04-01

463

Smart actuators: Valve Health Monitor (VHM) system  

NASA Astrophysics Data System (ADS)

The health of electromechanical systems (actuators) and specifically of solenoid valves is a primary concern at Kennedy Space Center (KSC). These systems control the storage and transfer of such commodities as liquid hydrogen. The potential for the failure of electromechanical systems to delay a scheduled launch or to cause personnel injury requires continual maintenance and testing of the systems to ensure their readiness. Monitoring devices need to be incorporated into these systems to verify the health and performance of the valves during real operating conditions. It is very advantageous to detect degradation and/or potential problems before they happen. This feature will not only provide safer operation but save the cost of unnecessary maintenance and inspections. Solenoid valve status indicators are often based upon microswitches that work by physically contacting a valve's poppet assembly. All of the physical contact and movement tends to be very unreliable and is subject to wear and tear of the assemblies, friction, breakage of the switch, and even leakage of the fluid (gas or liquid) in the valve. The NASA Instrumentation Branch, together with its contractor, ASRC Aerospace, has developed a solenoid valve smart current signature sensor that monitors valves in a noninvasive mode. The smart system monitors specific electrical parameters of the solenoid valves and detects and predicts the performance and health of the device. The information obtained from the electrical signatures of these valves points to not only electrical components failures in the valves but also mechanical failures and/or degradations.

Perotti, José; Lucena, Angel; Burns, Bradley

2006-06-01

464

Transapical transcatheter aortic valve implantation in a complex aortic surgical patient: A case involving the youngest valve-in-valve implantation with a 29 mm transcather valve  

PubMed Central

The present article reports a case involving a 29-year-old man who developed severe cardiac failure (New York Heart Association class IV). He had a complex surgical history, beginning with the repair of an anterior sinus of Valsalva aneurysm and closure of a ventricular septal defect at eight months of age. His residual Valsalva aneurysm and mixed aortic valve disease necessitated mechanical aortic valve replacement at 14 years of age. One year later, he developed coagulase-negative staphylococcal prosthetic valve infective endocarditis, necessitating an additional replacement of his valve with a pulmonary homograft. Subsequent follow-up revealed a dilated ascending aorta (6 cm) and increased regurgitation through his homograft, with significant dilation of the left ventricle. At 20 years of age, he underwent excision of the aneurysmal ascending aorta and arch of the aorta, and the aortic valve was replaced with a 29 mm bioprosthetic valve. This proved satisfactory for nine years until he presented at Guy’s and St Thomas’ National Health Services Foundation Trust (London, United Kingdom) with severe aortic regurgitation. His logistic EuroScore was 5.9 and Parsonnet score was 17 but, due to extensive previous surgery, he was considered and accepted for transcatheter aortic valve implantation. A 29 mm Edwards Sapien valve (Edwards Lifesciences, USA) was successfully implanted using a valve-in-valve procedure. The patient remained well and symptom free at early follow-up. Technical aspects of this complex adult congenital case that, to the authors’ knowledge is the youngest case of transcatheter aortic valve implantation and the first 29 mm valve-in-valve procedure, are discussed.

Attia, Rizwan; Visagan, Ravi; Nowell, Justin; Chadalavada, Sucharitha; Thomas, Martyn; Bapat, Vinne

2012-01-01

465

Transcatheter aortic valve update 2013.  

PubMed

Cumulative evidence has demonstrated that transcatheter aortic valve implantation (TAVI) constitutes an effective treatment option for patients with severe symptomatic aortic stenosis and a high operative risk. New valve designs and TAVI-enabling devices have simplified the procedure, reduced the risk of complications, and broadened the applications of this treatment. The global adoption of TAVI allows us to appreciate the advantages, potentialities and caveats of the technology, identify patients who would benefit from TAVI and stratify more accurately the risk of complications. The focus of this article is to discuss the advances in this field, present the current evidence, and highlight the developments and strategies proposed to address the limitations of TAVI treatment. PMID:24025965

Bourantas, Christos V; Van Mieghem, Nicolas M; Soliman, Osama; Campos, Carlos A M; Iqbal, Javaid; Serruys, Patrick W

2013-09-10

466

Microemboli in aortic valve replacement.  

PubMed

Microembolic signals (MES) can be detected in many recipients of mechanical aortic valve prostheses by transcranial Doppler ultrasound. The nature and etiology of these MES have remained unclear for a long time. The solid and gaseous nature of MES are discussed, as well as whether or not MES may reflect artifacts. Recently, the gaseous nature of these MES has been widely established. To understand the physics of bubble formation related to mechanical heart valve prostheses, it is necessary to discuss the different types of cavitation occurring at the prostheses and the conditions leading to the degassing of blood. We describe the history of transcranial Doppler ultrasound-techniques and the current techniques in the measurement of these signals. Furthermore, the possible clinical impact of MES, as well as strategies for the design of new prostheses and surgical alternatives to diminish their load are discussed. PMID:17173501

Nötzold, Axel; Khattab, Ahmed A; Eggers, Jürgen

2006-11-01

467

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

468

Management of Moderate Functional Tricuspid Valve Regurgitation at the Time of Pulmonary Valve Replacement: Is Concomitant Tricuspid Valve Repair Necessary?  

Microsoft Academic Search

Congenital heart defects with a component of pulmonary stenosis are often palliated in childhood by disrupting the pulmonary\\u000a valve. Patients often undergo subsequent pulmonary valve replacement (PVR) to protect the heart from the consequences of pulmonary\\u000a regurgitation. In the presence of associated moderate functional tricuspid valve (TV) regurgitation, it is unclear what factors\\u000a contribute to persistent TV regurgitation following PVR.

Brian Kogon; Manisha Patel; Traci Leong; Michael McConnell

2010-01-01

469

Leakage Rates for Cryolab Valves  

SciTech Connect

This note summarizes a brief study on the leakage rates of cryolab valves due to the failure of the valve packings. The {Delta}r gap between the shaft and the packing, the fluid (Ar or N2), the {Delta}p (atm) between the fluid and atmosphere, and the initial temperature of the escaping gas were varied to determine the resulting leakage rate. The heat leak in watts required to vaporize the liquid which provides the indicated flow rates is also included in the results. The dimensions used in the calculations were acquired over the telephone and/or found on the enclosed drawing from Cryolab. There is no implication that Cryolab was any better or worse than other valve manufacturers. They were kind enough to provide the detail needed for this study. The fluid properties were found in Ar and N2 Property handbooks. The results of this study are shown graphically and listed on accompanying spread sheets. The spread sheets and graphs can be found on the disc JW4 in the MassFlow folder.

Wendlandt, J.M.; /Fermilab

1988-11-02

470

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

471

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

472

Thermostatic steam trap with self-centering valve  

Microsoft Academic Search

This patent describes thermostatic steam trap comprising: a hollow body having an inlet opening, an outlet opening; a valve seat formed in the outlet opening; a valve adapted to seal the outlet opening in cooperation with the valve seat; thermostatic actuating means adapted to move the valve into and out of sealing contact with the valve seat; and a baffle

Alesson

1987-01-01

473

Water hammer caused by closure of turbine safety spherical valves  

Microsoft Academic Search

This paper investigates water hammer effects caused by closure of spherical valves against the discharge. During the first phase of modernisation of Perucica high-head hydropower plant (HPP), Montenegro, safety spherical valves (inlet turbine valves) have been refurbished on the first two Pelton turbine units. The valve closure is controlled by the valve actuator (hydraulic servomotor). Because the torque acting on

U. Karadzic; A. Bergant; P. Vukoslavcevic

2010-01-01

474

How valve hammer causes knocking in triplex pumps  

Microsoft Academic Search

This article investigates valve hammer as opposed to water hammer in triplex pumps, both of which produce knocking under certain distinctly different hydraulic operations. The occurrence of water hammer is reviewed and the development of valve hammer is discussed and documented. This work examines normal valve operation and abnormal operations at higher speeds where valve lag develops and valve hammer

1983-01-01

475

Evidence for rejection of homograft cardiac valves in infants  

Microsoft Academic Search

Objective: Concern about the durability of small homograft cardiac valves has been expressed by surgeons, and evidence has been found that homograft valves evoke a recipient immune response. We reviewed our experience with homograft valves for evidence of rejection. Methods: A search of our files revealed 11 homograft cardiac valves removed at reoperation and one at autopsy. Six valves were

Bijal Rajani; Roger B. Mee; Norman B. Ratliff

1998-01-01

476

Evaluation of Two-Way Valves for Respiratory Testing.  

National Technical Information Service (NTIS)

A comparison of four commonly used respiratory two-way valves, the Collins 'J' valve, a Modified Otis-McKerrow valve (with vane), the Collins 'Triple J' valve, and a modified Collins High Velocity exercise valve, was conducted to enable selection of a val...

R. H. James D. Goulding F. Pizzo

1974-01-01

477

Police Training.  

ERIC Educational Resources Information Center

|The third and fourth annual reports on law enforcement training in New Jersey ("Police Training: The Key to Professional Police Service," 1964-65 and 1965-66) review the powers, responsibilities, and duties of the Police Training Commission; law enforcement officers trained (including failures and total enrollments); hours of programed and other…

New Jersey State Dept. of Law and Public Safety, Trenton.

478

100. INTERIOR OF SKID 9A: VENT VALVE AND RELIEF VALVE ...  

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

100. INTERIOR OF SKID 9A: VENT VALVE AND RELIEF VALVE FOR RAPID-LOAD LIQUID OXYGEN TANK - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

479

MI-06-8 Auxiliary Air Solenoid Valve(s) Used With A Flow ...  

Center for Food Safety and Applied Nutrition (CFSAN)

Text Version... Specialists FROM: Milk Safety Branch (HFS-626) SUBJECT: Auxiliary Air Solenoid Valve(s) Used With A Flow Diversion Device It ... More results from www.fda.gov/downloads/food/guidanceregulation

480

Percutaneous implantation of CoreValve aortic prostheses in patients with a mechanical mitral valve.  

PubMed

Concerns exist in the field of transcatheter aortic valve implantation regarding the treatment of patients with mechanical mitral valve for possible interference between the percutaneous aortic valve and the mechanical mitral prosthesis. We report our experience with percutaneous aortic valve implantation in 4 patients with severe aortic stenosis, previously operated on for mitral valve replacement with a mechanical prosthesis. All patients underwent uneventful percutaneous retrograde CoreValve implantation (CoreValve Inc, Irvine, CA). No deformation of the nitinol tubing of the prostheses (ie, neither distortion nor malfunction of the mechanical valve in the mitral position) occurred in any of the patients. All patients are alive and asymptomatic at a mean follow-up of 171 days. PMID:19853076

Bruschi, Giuseppe; De Marco, Federico; Oreglia, Jacopo; Colombo, Paola; Fratto, Pasquale; Lullo, Francesca; Paino, Roberto; Frigerio, Maria; Martinelli, Luigi; Klugmann, Silvio

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