Regulatory control of nuclear facility valves and their actuators

International Nuclear Information System (INIS)

1993-01-01

The methods and procedures by which the Finnish Centre for Radiation and Nuclear Safety (STUK) regulates valves and their actuators in nuclear power plants and in other nuclear facilities are specified in the guide. The scope of regulation depends on the Safety Class of the valve and the actuator in question. The Safety Classification principles for the systems, structures and components of the nuclear power plants are described in the guide YVL 2.1 and the regulatory control of the nuclear facility safety valves is described in the guide YVL 5.4

Investigations on pneumatically forced-actuated compressor valves

Science.gov (United States)

Stöckel, Christian; Thomas, Christiane; Nickl, Jörg; Hesse, Ullrich

2017-08-01

In the present paper the performance of a novel designed valve for reciprocating piston machines is investigated, which makes existing compressors utilizable for operating as expander. Three design parameters were identified as critical for the valves performance particularly in forced actuated mode. Within a numerical simulation a study on the crucial geometrical parameters, the influence could be observed. Afterwards the experimental setup for the integral test of the valve design is presented and also additional tests for single valve components.

Bistable (latching) solenoid actuated propellant isolation valve

Science.gov (United States)

Wichmann, H.; Deboi, H. H.

1979-01-01

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

Design and Performance Evaluation of an Electro-Hydraulic Camless Engine Valve Actuator for Future Vehicle Applications.

Science.gov (United States)

Nam, Kanghyun; Cho, Kwanghyun; Park, Sang-Shin; Choi, Seibum B

2017-12-18

This paper details the new design and dynamic simulation of an electro-hydraulic camless engine valve actuator (EH-CEVA) and experimental verification with lift position sensors. In general, camless engine technologies have been known for improving fuel efficiency, enhancing power output, and reducing emissions of internal combustion engines. Electro-hydraulic valve actuators are used to eliminate the camshaft of an existing internal combustion engines and used to control the valve timing and valve duration independently. This paper presents novel electro-hydraulic actuator design, dynamic simulations, and analysis based on design specifications required to satisfy the operation performances. An EH-CEVA has initially been designed and modeled by means of a powerful hydraulic simulation software, AMESim, which is useful for the dynamic simulations and analysis of hydraulic systems. Fundamental functions and performances of the EH-CEVA have been validated through comparisons with experimental results obtained in a prototype test bench.

A numerical insight into elastomer normally closed micro valve actuation with cohesive interfacial cracking modelling

Science.gov (United States)

Wang, Dongyang; Ba, Dechun; Hao, Ming; Duan, Qihui; Liu, Kun; Mei, Qi

2018-05-01

Pneumatic NC (normally closed) valves are widely used in high density microfluidics systems. To improve actuation reliability, the actuation pressure needs to be reduced. In this work, we utilize 3D FEM (finite element method) modelling to get an insight into the valve actuation process numerically. Specifically, the progressive debonding process at the elastomer interface is simulated with CZM (cohesive zone model) method. To minimize the actuation pressure, the V-shape design has been investigated and compared with a normal straight design. The geometrical effects of valve shape has been elaborated, in terms of valve actuation pressure. Based on our simulated results, we formulate the main concerns for micro valve design and fabrication, which is significant for minimizing actuation pressures and ensuring reliable operation.

IEEE Std 382-1980: IEEE standard for qualification of safety-related valve actuators

International Nuclear Information System (INIS)

Anon.

1992-01-01

This standard describes the qualification of all types of power-driven valve actuators, including damper actuators, for safety-related functions in nuclear power generating stations. This standard may also be used to separately qualify actuator components. This standard establishes the minimum requirements for, and guidance regarding, the methods and procedures for qualification of all safety-related functions of power-driven valve actuators

Actuation and system design and evaluation OMS engine shutoff valve, Volume 1. [space shuttles

Science.gov (United States)

Dunn, V. B.

1975-01-01

A technology program was conducted to identify and verify the optimum valve and actuation system concept for the Space Shuttle Orbit Maneuvering System engine. Of major importance to the valve and actuation system selection was the ten-year, 100-mission, 10,000-cycle life requirement, while maintaining high reliability, low leakage, and low weight. Valve and actuation system concepts were comparatively evaluated against past valve failure reports and potential failure modes due to the shuttle mission profile to aid in the selection of the most optimum concept for design, manufacture and verification testing. Two valve concepts were considered during the preliminary design stage; i.e., the moving seat and lifting ball. Two actuation systems were manufactured and tested. Test results demonstrate the viability of a lifting ball concept as well as the applicability of an ac motor actuation system to best meet the requirements of the shuttle mission.

Inducement of Design Parameters for Reliability Improvement of Servo Actuator for Hydraulic Valve Operation

Energy Technology Data Exchange (ETDEWEB)

Sung, Baek Ju; Kim, Do Sik [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

2014-05-15

The precision hydraulic valve is widely used in various industrial field like aircraft, automobile, and general machinery. Servo actuator is the most important device for driving the precise hydraulic valve. The reliable operation of servo actuator effects on the overall hydraulic system. The performance of servo actuator relies on frequency response and step response according to arbitrary input signal. In this paper, we performed the analysis for the components of servo actuator to satisfy the reliable operation and response characteristics through the reliability analysis, and also induced the design parameters to realize the reliable operation and fast response characteristics of servo actuator for hydraulic valve operation through the empirical knowledge of experts and electromagnetic theories. We suggested the design equations to determine the values of design parameters of servo actuator as like bobbin size, length of yoke and plunger and turn number of coil, and verified the achieved design values through FEM analysis and performance tests using some prototypes of servo actuators adapted in hydraulic valve.

Real-Time Prognostics of a Rotary Valve Actuator

Science.gov (United States)

Daigle, Matthew

2015-01-01

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

The analysis of actuating mechanism and review of concepts for the vortex valve

International Nuclear Information System (INIS)

Park, Jong Kyun; Sim, Yun Seop; Joung, Sae Won; Lee, Ki Young; Lee, Jun; Kim, Young In

1995-12-01

To understand the basic features of the passive fluidic device, which is increasing available core cooling water from the safety injection tanks in the KNGR, review of the existing vortex valves concepts and analysis of the actuating mechanism of them have been performed and the results are as following: * Preliminary methodology development for parallel two water columns behavior, which is similar to the SIT valve actuation condition * Preliminary methodology for the vortex value actuation features * Analysis of the parallel water columns behavior and vortex valve actuation features using the results of above activities * Further works to be done in the analytical methodology. 16 figs., 2 refs. (Author) .new

Integrated nozzle - flapper valve with piezoelectric actuator and isothermal chamber: a feedback linearization multi control device

Energy Technology Data Exchange (ETDEWEB)

Kamali, Mohammadreza; Jazayeri, Seyed Ali [K. N.Toosi University of Technology, Tehran (Iran, Islamic Republic of); Najafi, Farid [University of Guilan, Rasht (Iran, Islamic Republic of); Kawashima, Kenji [Tokyo Medical and Dental University, Tokyo (Japan); Kagawa, Toshiharu [Tokyo Institute of Technology, Tokyo (Japan)

2016-05-15

This paper introduces a new nozzle-flapper valve with isothermal chamber using piezoelectric actuator. It controls the pressure and flow rate simply, effectively and separately. The proposed valve uses isothermal chamber presenting practical isothermal condition due to its large heat transfer interfaces filled by metal wool. The valve uses stacked type piezoelectric actuator with unique advantages. By using this valve, a simple method has been fulfilled to control flow rate or pressure of ideal gases in a pneumatic actuators. Experimental results demonstrated applications of the proposed valve to control either pressure or flow rate in pneumatic circuits. This valve can be also used in the pilot stage valve to actuate the main stage of a much bigger pneumatic valve. Designated structure contains only one pressure sensor installed on the isothermal control chamber, capable of controlling both pressure and flow rate. The desired output mass flow rate of the valve is controlled by the pressure changes during positioning of piezoelectric actuator at proper position. The proposed valve can control steady and unsteady oscillatory flow rate and pressure effectively, using nonlinear control method such as feedback linearization approach. Its effectiveness is demonstrated and validated through simulation and experiments.

The Actuator Fault Diagnosis Based on the Valve Friction

Directory of Open Access Journals (Sweden)

Jiajiang Li

2014-08-01

Full Text Available Control valve (actuator is the frequently moving terminal Instrument of the control system. To avoid the leaking of the actuator, there is packing at the moving parts. However, the friction caused by the packing can do harm to the control of the system. The washing effect of the media, high temperature, high pressure, frequent movement and other effects can result in the leaking of the packing and the deformation of the valve stem, which causes the change of the friction. The study of the control of the friction has always been an interesting topic in the industry. In this paper, we theoretically analyze the relationship of the friction of the packing and the static performance of the control valve, and offer a method to check the quality of the moving parts by attaching a strain gage (strain rosette to the empty part of the valve stem. This method has been demonstrated via experiment and a method to do error detection is provided at last.

Normally-Closed Zero-Leak Valve with Magnetostrictive Actuator

Science.gov (United States)

Ramspacher, Daniel J. (Inventor); Richard, James A. (Inventor)

2017-01-01

A non-pyrotechnic, normally-closed, zero-leak valve is a replacement for the pyrovalve used for both in-space and launch vehicle applications. The valve utilizes a magnetostrictive alloy for actuation, rather than pyrotechnic charges. The alloy, such as Terfenol-D, experiences magnetostriction, i.e. a gross elongation, when exposed to a magnetic field. This elongation fractures a parent metal seal, allowing fluid flow through the valve. The required magnetic field is generated by redundant coils that are isolated from the working fluid.

Worcester 1 Inch Solenoid-Actuated Gas-Operated VPS System Ball Valve

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

1 inch Gas-operated full-port ball valve incorporates a solenoid and limit switches as integral parts of the actuator. The valve is normally open and fails safe to the closed position. The associated valve position switch is class GS

High Reliability Cryogenic Piezoelectric Valve Actuator, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Piezoelectric actuators constructed with the "smart material" PZT offer many potential advantages for use in NASA cryo-valve missions relative to conventional...

Hydraulic engine valve actuation system including independent feedback control

Science.gov (United States)

Marriott, Craig D

2013-06-04

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

Electric actuator for the sempell gate valve

Energy Technology Data Exchange (ETDEWEB)

Herbstritt, E.C.

1996-12-01

The automation of valves has a primary importance in the scope of central control and regulation of power generation processes in power plants and especially in nuclear power plants. AUMA WERNER RIESTER GmbH & Co. KG is considered a leading manufacturer of electric actuators for the automation of valves. More than 30 years experience in designing, developing, and manufacturing provide a sound basis for offering reliable products, especially for nuclear applications. The quality assurance system of AUMA was developed according to 10 CFR 50, Appendix B and has been consistently accomplished. The program was certified by the TUV Germany (Technical Authorized Inspection Agency), according to ISO-9001, in 1994. AUMA offers two actuator type ranges for application in nuclear power plants. The range SAI is qualified according to IEEE 382-1978 and is designed for inside containment. The range SAN is qualified according to IEEE 382-1985 and KTA 3504-1988 for use in non-radioactive applications in the nuclear power plants.

Modelling of Moving Coil Actuators in Fast Switching Valves Suitable for Digital Hydraulic Machines

DEFF Research Database (Denmark)

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

2015-01-01

an estimation of the eddy currents generated in the actuator yoke upon current rise, as they may have significant influence on the coil current response. The analytical model facilitates fast simulation of the transient actuator response opposed to the transient electro-magnetic finite element model which......The efficiency of digital hydraulic machines is strongly dependent on the valve switching time. Recently, fast switching have been achieved by using a direct electromagnetic moving coil actuator as the force producing element in fast switching hydraulic valves suitable for digital hydraulic...... machines. Mathematical models of the valve switching, targeted for design optimisation of the moving coil actuator, are developed. A detailed analytical model is derived and presented and its accuracy is evaluated against transient electromagnetic finite element simulations. The model includes...

Sliding spool design for reducing the actuation forces in direct operated proportional directional valves: Experimental validation

International Nuclear Information System (INIS)

Amirante, Riccardo; Distaso, Elia; Tamburrano, Paolo

2016-01-01

Highlights: • An innovative procedure to design a commercial proportional directional valve is shown. • Experimental tests are performed to demonstrate the flow force reduction. • The design is improved by means of a previously made optimization procedure. • Great reduction in the flow forces without reducing the flow rate is demonstrated. - Abstract: This paper presents the experimental validation of a new methodology for the design of the spool surfaces of four way three position direct operated proportional directional valves. The proposed methodology is based on the re-design of both the compensation profile (the central conical surface of the spool) and the lateral surfaces of the spool, in order to reduce the flow forces acting on the spool and hence the actuation forces. The aim of this work is to extend the application range of these valves to higher values of pressure and flow rate, thus avoiding the employment of more expensive two stage configurations in the case of high-pressure conditions and/or flow rate. The paper first presents a theoretical approach and a general strategy for the sliding spool design to be applied to any four way three position direct operated proportional directional valve. Then, the proposed approach is experimentally validated on a commercially available valve using a hydraulic circuit capable of measuring the flow rate as well as the actuation force over the entire spool stroke. The experimental results, performed using both the electronic driver provided by the manufacturer and a manual actuation system, show that the novel spool surface requires remarkably lower actuation forces compared to the commercial configuration, while maintaining the same flow rate trend as a function of the spool position.

System and method for controlling engine knock using electro-hydraulic valve actuation

Science.gov (United States)

Brennan, Daniel G

2013-12-10

A control system for an engine includes a knock control module and a valve control module. The knock control module adjusts a period that one or more of an intake valve and an exhaust valve of a cylinder are open based on engine knock corresponding to the cylinder. The valve control module, based on the adjusted period, controls the one or more of the intake valve and the exhaust valve using one or more hydraulic actuators.

Worcester 1 Inch Solenoid-Actuated Gas Operated SCHe System Valves

International Nuclear Information System (INIS)

VAN KATWIJK, C.

2000-01-01

1 inch Gas-operated full-port ball valves incorporate a solenoid and limit switches as integral parts of the actuator. These valves are normally open and fail safe to the open position (GOV-1*02 and 1*06 fail closed) to provide a flow path of helium gas to the MCO under helium purge and off-normal conditions when the MCO is isolated

A study on flow distribution for integrated hybrid actuator by analysis of reed valve

Energy Technology Data Exchange (ETDEWEB)

Woo, Jang Mi; Kang, Seung Hwan; Ko, Han Seo [Sungkyunkwan University, Suwon (Korea, Republic of); Goo, Nam Seo; Li, Yong Zhe [Konkuk University, Seoul (Korea, Republic of)

2016-05-15

Many studies have been conducted recently on an integrated hybrid actuator due to the increasing need for unmanned aircraft and guided weapons. In this study, flow distribution was analyzed for a reed valve which was used for flow regulation to improve the performance of the actuator. By using a Fluid structural interaction (FSI) technique with Computational fluid dynamics (CFD) having a moving mesh, numerical analysis was performed according to the thickness, shape and driving frequency of the reed valve. From the calculated results, the maximum performance of the reed valve was found at the valve thickness of 0.15 mm and the driving frequency of 250 Hz for a no-load state. The optimum thickness and shape for the valve for each driving frequency were also realized.

Valve system incorporating single failure protection logic

Science.gov (United States)

Ryan, Rodger; Timmerman, Walter J. H.

1980-01-01

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

Optimum Design of a Moving Coil Actuator for Fast-Switching Valves in Digital Hydraulic Pumps and Motors

DEFF Research Database (Denmark)

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

2015-01-01

Fast-switching seat valves suitable for digital hydraulic pumps and motors utilize direct electromagnetic actuators, which must exhibit superior transient performance to allow efficient operation of the fluid power pump/motor. A moving coil actuator resulting in a minimum valve switching time...... is designed for such valves using transient finite-element analysis of the electromagnetic circuit. The valve dynamics are coupled to the fluid restrictive forces, which significantly influence the effective actuator force. Fluid forces are modeled based on transient computational fluid dynamics models....... The electromagnetic finite-element model is verified against experimental measurement, and used to design an optimum moving coil actuator for the application considering different voltage-current ratios of the power supply. Results show that the optimum design depends on the supply voltage-current ratio, however...

Hydraulically-actuated operating system for an electric circuit breaker

Science.gov (United States)

Barkan, Philip; Imam, Imdad

1978-01-01

This hydraulically-actuated operating system comprises a cylinder, a piston movable therein in an opening direction to open a circuit breaker, and an accumulator for supplying pressurized liquid to a piston-actuating space within the cylinder. A normally-closed valve between the accumulator and the actuating space is openable to allow pressurized liquid from the accumulator to flow through the valve into the actuating space to drive the piston in an opening direction. A vent is located hydraulically between the actuating space and the valve for affording communication between said actuating space and a low pressure region. Flow control means is provided for restricting leakage through said vent to a rate that prevents said leakage from substantially detracting from the development of pressure within said actuatng space during the period from initial opening of the valve to the time when said piston has moved through most of its opening stroke. Following such period and while the valve is still open, said flow control means allows effective leakage through said vent. The accumulator has a limited capacity that results in the pressure within said actuating space decaying promptly to a low value as a result of effective leakage through said vent after the piston has moved through a circuit-breaker opening stroke and while the valve is in its open state. Means is provided for resetting the valve to its closed state in response to said pressure decay in the actuating space.

Baking Powder Actuated Centrifugo-Pneumatic Valving for Automation of Multi-Step Bioassays

Directory of Open Access Journals (Sweden)

David J. Kinahan

2016-10-01

Full Text Available We report a new flow control method for centrifugal microfluidic systems; CO2 is released from on-board stored baking powder upon contact with an ancillary liquid. The elevated pressure generated drives the sample into a dead-end pneumatic chamber sealed by a dissolvable film (DF. This liquid incursion wets and dissolves the DF, thus opening the valve. The activation pressure of the DF valve can be tuned by the geometry of the channel upstream of the DF membrane. Through pneumatic coupling with properly dimensioned disc architecture, we established serial cascading of valves, even at a constant spin rate. Similarly, we demonstrate sequential actuation of valves by dividing the disc into a number of distinct pneumatic chambers (separated by DF membranes. Opening these DFs, typically through arrival of a liquid to that location on a disc, permits pressurization of these chambers. This barrier-based scheme provides robust and strictly ordered valve actuation, which is demonstrated by the automation of a multi-step/multi-reagent DNA-based hybridization assay.

Development of multilayer piezoelectric actuator valve for JT-60

International Nuclear Information System (INIS)

Miyo, Yasuhiko; Hiratsuka, Hajime; Masui, Hiroshi; Hosogane, Nobuyuki; Miya, Naoyuki

2001-11-01

In order to improve the gas injection valve used for the operation of JT-60, a new type of valve (multilayer piezoelectric actuator valve) was developed. The conventional valve (bimorph piezoelectric valve) has been used for 15 years since the beginning of experimental operation in April, 1985. However, it came to be hard to keep the performance of the valve because of the deterioration of the driving source, i.e. piezoelectric element. Developments of the new valve were carried out based on experiences through experimental operations in JT-60. Requirements for the design are: (1) to be hard structure for making a sheet leak, (2) to allow a repair work at atmosphere side without an air vent of the vacuum vessel, (3) to be more smaller and lighter compared with the conventional one, and (4) to have a high maintenance efficiency by utilizing of the commercial piezoelectric elements and power supplies. The newly developed valve was examined with various tests such as gas flow characteristic test, high magnetic field proof test, high temperature proof test and gas flow rate test for aged deterioration. Results, confirm that the performance of the valve is applicable for JT-60 operations. (author)

Failure analysis of globe control valves with spring-diaphragm actuator for nuclear power plant applications

International Nuclear Information System (INIS)

Khan, M.R.; Chen, W.W.H.; Wang, T.Y.

1997-01-01

The results of the failure analysis of a globe control valve with spring-diaphragm actuator indicated that the diaphragm failed because the service loading is close to the strength of the diaphragm. The resulting impact force is significantly larger than the plug guide strength and that cause it to bulge out after the impact. To improve the valve performance, proper torque should be used to tighten the actuator diaphragm case fasteners. A stronger actuator diaphragm could be used to provide additional safety margin during operation. Stiffening the plug guide may avoid jamming the bushing

Effects of dynamic loading of motor-operated valve actuators

International Nuclear Information System (INIS)

Damerell, P.S.; Daubresse, S.; Wolfe, K.J.; Dogan, T.; Gleeson, J.

1994-01-01

Experience has shown that valves with rising, nonrotating stems that are operated using electro-motor driven actuators can be susceptible to changes in output thrust at a constant torque switch setting as a result of changes in stem load time history. This effect is a concern because tests on these types of valves to verify thrust achieved at torque switch trip are often performed in situ under load conditions different from the required performance conditions. As part of a motor-operated valve research program being carried out by the Electric Power Research Institute, tests of typical electric motor actuators used with nuclear services valves have been performed. The test results show that changes in output thrust with load time history occur o varying degrees on different stem and stem nut combinations. When the effect exists, there is generally an increase in thrust at torque switch trip when load is developed rapidly from low initial loads, compared to when load is developed slowly. The effect is mainly a result of changes in the coefficient of friction at the stem-stem nut interface. The coefficient of friction is temporarily reduced under rapid loading conditions from low initial load, leading to increased thrust. The root cause is hypothesized to be a open-quotes squeeze-filmclose quotes effect, whereby mixed-mode lubrication (hydrodynamic plus boundary) temporarily replaces boundary lubrication. This paper describes the results of tests performed to better understand the phenomenon

A study on modelling of a butterfly-type control valve by a pneumatic actuator

International Nuclear Information System (INIS)

Hwang, I Cheol; Park, Cheol Jae

2009-01-01

This paper studies on the modelling of a butterfly-type control valve actuating by an on-off pneumatic solenoid valve. The mathematical model is composed of nonlinear differential equations three parts: (i) a solenoid valve, (ii) a pneumatic cylinder, (iii) a rotary-type butterfly valve. The flow characteristics of the butterfly control valve is analysed by a computer simulator, then its simple transfer function is identified from the step responses.

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

International Nuclear Information System (INIS)

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

1997-07-01

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

SMA spring-based artificial muscle actuated by hot and cool water using faucet-like valve

Science.gov (United States)

Park, Cheol Hoon; Son, Young Su

2017-04-01

An artificial muscle for a human arm-like manipulator with high strain and high power density are under development, and an SMA(Shape memory alloy) spring is a good actuator for this application. In this study, an artificial muscle composed of a silicon tube and a bundle of SMA(Shape memory alloy) springs is evaluated. A bundle of SMA springs consists of five SMA springs which are fabricated by using SMA wires with a diameter of 0.5 mm, and hot and cool water actuates it by heating and cooling SMA springs. A faucet-like valve was also developed to mix hot water and cool water and control the water temperature. The mass of silicon tube and a bundle of SMA springs is only 3.3 g and 2.25 g, respectively, and the total mass of artificial muscle is 5.55 g. It showed good actuating performance for a load with a mass of 2.3 kg and the power density was more than 800 W/kg for continuous valve switching with a cycle of 0.6 s. The faucet-like valve can switch a water output from hot water to cold water within 0.3s, and the artificial muscle is actuated well in response to the valve position and speed. It is also presented that the temperature of the mixed water can be controlled depending on the valve position, and the displacement of the artificial muscle can be controlled well by the mixed water. Based on these results, SMA spring-based artificial muscle actuated by hot and cool water could be applicable to the human arm-like robot manipulators.

Simulation of proportional control of hydraulic actuator using digital hydraulic valves

Science.gov (United States)

Raghuraman, D. R. S.; Senthil Kumar, S.; Kalaiarasan, G.

2017-11-01

Fluid power systems using oil hydraulics in earth moving and construction equipment have been using proportional and servo control valves for a long time to achieve precise and accurate position control backed by system performance. Such valves are having feedback control in them and exhibit good response, sensitivity and fine control of the actuators. Servo valves and proportional valves are possessing less hysteresis when compared to on-off type valves, but when the servo valve spools get stuck in one position, a high frequency called as jitter is employed to bring the spool back, whereas in on-off type valves it requires lesser technology to retract the spool. Hence on-off type valves are used in a technology known as digital valve technology, which caters to precise control on slow moving loads with fast switching times and with good flow and pressure control mimicking the performance of an equivalent “proportional valve” or “servo valve”.

Drive piston assembly for a valve actuator assembly

Science.gov (United States)

Sun, Zongxuan

2010-02-23

A drive piston assembly is provided that is operable to selectively open a poppet valve. The drive piston assembly includes a cartridge defining a generally stepped bore. A drive piston is movable within the generally stepped bore and a boost sleeve is coaxially disposed with respect to the drive piston. A main fluid chamber is at least partially defined by the generally stepped bore, drive piston, and boost sleeve. First and second feedback chambers are at least partially defined by the drive piston and each are disposed at opposite ends of the drive piston. At least one of the drive piston and the boost sleeve is sufficiently configured to move within the generally stepped bore in response to fluid pressure within the main fluid chamber to selectively open the poppet valve. A valve actuator assembly and engine are also provided incorporating the disclosed drive piston assembly.

Overflow control valve

International Nuclear Information System (INIS)

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

1982-01-01

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

Actuation and Control of a Micro Electrohydraulic Digital Servo Valve

Energy Technology Data Exchange (ETDEWEB)

Yu, Z Q; Hu, M J; Pei, X; Ruan, J [MOE Key Laboratory of Mechanical Manufacture and Automation Zhejiang University of Technology, 310014 (China)

2006-10-15

Structure of the micro digital servo valve is given. A micro stepper motor is used as electrical-to-mechanical interface of the valve. A special mechanical device is designed to convert the rotation of the stepper motor into the linear motion of the spool. This moving conversion device functions through an eccentric ball head rigidly connected to the axis of the stepper motor and plugged into a slot at the central spool land. While the stepper motor rotates, the eccentric ball head will actuate the spool to make a linear motion. Unlike conventional servo or proportional valves, in which the spool is forced to central position by a spring force, when the current supply is switched off, the digital valve has a program to control the spool to its central position each time the electrical power supply is switched on or off. The two end screws are used to adjust the position of the sleeve to sustain a mechanical central position coincided with electrical central position given by the stepper motor after initialization. The adjustment has to be carried once before the first time the servo valve is put into service. This paper presents theoretical analysis and experimental study of dynamic characteristics of the proposed micro digital servo valve. Experimental results demonstrated that the valve takes the advantage of high accuracy and fast response.

Actuation and Control of a Micro Electrohydraulic Digital Servo Valve

International Nuclear Information System (INIS)

Yu, Z Q; Hu, M J; Pei, X; Ruan, J

2006-01-01

Structure of the micro digital servo valve is given. A micro stepper motor is used as electrical-to-mechanical interface of the valve. A special mechanical device is designed to convert the rotation of the stepper motor into the linear motion of the spool. This moving conversion device functions through an eccentric ball head rigidly connected to the axis of the stepper motor and plugged into a slot at the central spool land. While the stepper motor rotates, the eccentric ball head will actuate the spool to make a linear motion. Unlike conventional servo or proportional valves, in which the spool is forced to central position by a spring force, when the current supply is switched off, the digital valve has a program to control the spool to its central position each time the electrical power supply is switched on or off. The two end screws are used to adjust the position of the sleeve to sustain a mechanical central position coincided with electrical central position given by the stepper motor after initialization. The adjustment has to be carried once before the first time the servo valve is put into service. This paper presents theoretical analysis and experimental study of dynamic characteristics of the proposed micro digital servo valve. Experimental results demonstrated that the valve takes the advantage of high accuracy and fast response

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

DEFF Research Database (Denmark)

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

2016-01-01

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

IEEE Std 382-1985: IEEE standard for qualification of actuators for power operated valve assemblies with safety-related functions for nuclear power plants

International Nuclear Information System (INIS)

Anon.

1992-01-01

This standard describes the qualification of all types of power-driven valve actuators, including damper actuators, for safety-related functions in nuclear power generating stations. This standard may also be used to separately qualify actuator components. This standard establishes the minimum requirements for, and guidance regarding, the methods and procedures for qualification of power-driven valve actuators with safety-related functions Part I describes the qualification process. Part II describes the standard qualification cases and their environmental parameters for the usual locations of safety-related equipment in a nuclear generating station. Part III describes the qualification tests outlined in 6.3.3

Remote actuated valve implant

Science.gov (United States)

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

2014-02-25

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

Explosive actuated valve

International Nuclear Information System (INIS)

Byrne, K.G.

1983-01-01

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

A Study on the Air Vent Valve of the Hydraulic Servo Actuator for Steam Control of Power Plants

International Nuclear Information System (INIS)

Lee, Yong Bum; Lee, Jong Jik

2016-01-01

To produce adequate electricity in nuclear and thermal power plants, an optimal amount of steam should be supplied to a generator connected to high- and low-pressure steam turbines. A turbine output control device, which is a special steam valve employed to supply or interrupt the steam to the turbine, is operated using a hydraulic servo actuator. In power plants, the performance of servo actuators is degraded by the air generated from the hydraulic system, or causes frequent failures owing to an increase in the wear of the seal. This is due to the seal being burnt as generated heat using the produced compressed air. Some power plants have exhausted air using a fixed orifice, and thus they encounter power loss due to mass flow exhaust. Failures are generated in hydraulic pumps, electric motors, and valves, which are frequently operated. In this study, we perform modeling and analysis of the load-sensing air-exhaust valves, which can be passed through very fine flow under normal use conditions, and exhaust mass flow air at the beginning stage as with existing fixed orifices. Then, we propose a method to prevent failures due to the compressed air, and to ensure the control accuracy of hydraulic servo actuators.

A Study on the Air Vent Valve of the Hydraulic Servo Actuator for Steam Control of Power Plants

Energy Technology Data Exchange (ETDEWEB)

Lee, Yong Bum; Lee, Jong Jik [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

2016-06-15

To produce adequate electricity in nuclear and thermal power plants, an optimal amount of steam should be supplied to a generator connected to high- and low-pressure steam turbines. A turbine output control device, which is a special steam valve employed to supply or interrupt the steam to the turbine, is operated using a hydraulic servo actuator. In power plants, the performance of servo actuators is degraded by the air generated from the hydraulic system, or causes frequent failures owing to an increase in the wear of the seal. This is due to the seal being burnt as generated heat using the produced compressed air. Some power plants have exhausted air using a fixed orifice, and thus they encounter power loss due to mass flow exhaust. Failures are generated in hydraulic pumps, electric motors, and valves, which are frequently operated. In this study, we perform modeling and analysis of the load-sensing air-exhaust valves, which can be passed through very fine flow under normal use conditions, and exhaust mass flow air at the beginning stage as with existing fixed orifices. Then, we propose a method to prevent failures due to the compressed air, and to ensure the control accuracy of hydraulic servo actuators.

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

DEFF Research Database (Denmark)

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

2018-01-01

The emerging digital displacement fluid power technology requires a new class of high-performance valves that can operate in harsh high-pressure conditions. To overcome the switching performance limitations of solenoids and to avoid the mechanical complexity of moving coil actuators, a novel elec......, and a simple mechanical design....

A rotary pneumatic actuator for the actuation of the exoskeleton knee joint

Directory of Open Access Journals (Sweden)

Jobin Varghese

2017-07-01

Full Text Available Rotary pneumatic actuators that are made out of linear one are always best suited for exoskeleton joint actuation due to its inherent power to weight ratio. This work is a modified version of knee actuation system that has already been developed and major modifications are made in order to make it more suitable for human wearing and also to reduce its bulkiness and complexity. The considered actuator system is a rotary actuator where a pulley converts the linear motion of the standard pneumatic piston into the rotary motion. To prove the capability of the actuator, its performance characteristics such as torque and power produced are compared to the required torque and power at the knee joint of the exoskeleton in swing phase and are found to be excellent. The two-way analysis of variance (ANOVA is performed to find the effect of the throat area valve on knee angle. The ANOVA shows the significant effect of the throat area variation on the knee angle flexion made by the proposed actuator. A relationship between the throat area of flow control valve, that is connected to the exit port of the direction control valve, and angular displacement of the knee joint has been formulated. This relationship can be used to design a control system to regulate the mass flow rate of air at the exit and hence the angular velocity of the knee joint can be controlled. Keywords: Driven pulley, Flow control valve, Rotary, Pneumatic cylinder

Survey of industrial coal conversion equipment capabilities: valves

Energy Technology Data Exchange (ETDEWEB)

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

1978-06-01

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

Recent performance experience with US light water reactor self-actuating safety and relief valves

Energy Technology Data Exchange (ETDEWEB)

Hammer, C.G.

1996-12-01

Over the past several years, there have been a number of operating reactor events involving performance of primary and secondary safety and relief valves in U.S. Light Water Reactors. There are several different types of safety and relief valves installed for overpressure protection of various safety systems throughout a typical nuclear power plant. The following discussion is limited to those valves in the reactor coolant systems (RCS) and main steam systems of pressurized water reactors (PWR) and in the RCS of boiling water reactors (BWR), all of which are self-actuating having a setpoint controlled by a spring-loaded disk acting against system fluid pressure. The following discussion relates some of the significant recent experience involving operating reactor events or various testing data. Some of the more unusual and interesting operating events or test data involving some of these designs are included, in addition to some involving a number of similar events and those which have generic applicability.

Optimization of Moving Coil Actuators for Digital Displacement Machines

DEFF Research Database (Denmark)

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

2016-01-01

This paper focuses on deriving an optimal moving coil actuator design, used as force pro-ducing element in hydraulic on/off valves for Digital Displacement machines. Different moving coil actuator geometry topologies (permanent magnet placement and magnetiza-tion direction) are optimized for actu......This paper focuses on deriving an optimal moving coil actuator design, used as force pro-ducing element in hydraulic on/off valves for Digital Displacement machines. Different moving coil actuator geometry topologies (permanent magnet placement and magnetiza-tion direction) are optimized...... for actuating annular seat valves in a digital displacement machine. The optimization objectives are to the minimize the actuator power, the valve flow losses and the height of the actuator. Evaluation of the objective function involves static finite element simulation and simulation of an entire operation...... designs requires approximately 20 W on average and may be realized in 20 mm × Ø 22.5 mm (height × diameter) for a 20 kW pressure chamber. The optimization is carried out using the multi-objective Generalized Differential Evolu-tion optimization algorithm GDE3 which successfully handles constrained multi-objective...

A magnetorheological actuation system: test and model

International Nuclear Information System (INIS)

John, Shaju; Chaudhuri, Anirban; Wereley, Norman M

2008-01-01

Self-contained actuation systems, based on frequency rectification of the high frequency motion of an active material, can produce high force and stroke output. Magnetorheological (MR) fluids are active fluids whose rheological properties can be altered by the application of a magnetic field. By using MR fluids as the energy transmission medium in such hybrid devices, a valving system with no moving parts can be implemented and used to control the motion of an output cylinder shaft. The MR fluid based valves are configured in the form of an H-bridge to produce bi-directional motion in an output cylinder by alternately applying magnetic fields in the two opposite arms of the bridge. The rheological properties of the MR fluid are modeled using both Bingham plastic and bi-viscous models. In this study, the primary actuation is performed using a compact terfenol-D rod driven pump and frequency rectification of the rod motion is done using passive reed valves. The pump and reed valve configuration along with MR fluidic valves form a compact hydraulic actuation system. Actuator design, analysis and experimental results are presented in this paper. A time domain model of the actuator is developed and validated using experimental data

Results of the motor-operated valve engineering and testing program

International Nuclear Information System (INIS)

Black, B.R.

1994-01-01

The Texas Utilities Electric Company (TU Electric) motor-operated valve (MOV) program for implementing the recommendations of Generic Letter 89-10 has typically included the following: refurbishing each actuator, verifying each actuator's as-built configuration, testing each actuator's motor on a dynamometer, testing each actuator's torque spring pack (which is used to control the torque developed), testing each fully refurbished and reassembled actuator on a torque test stand, and testing as many MOVs as practicable both without fluid flow through the valve and with the maximum test conditions reasonably achievable (static and differential pressures (DP) conditions, respectively). Test data are acquired at 1,000 samples per second for stem thrust, stem torque, stem position, actuator compensator spring pack deflection, actuator torque spring pack deflection, motor current, motor voltage, motor three-phase power, valve upstream pressure, and valve downstream pressure, wherever practicable

Preventive maintenance basis: Volume 16 -- Power operated relief valves, solenoid actuated. Final report

International Nuclear Information System (INIS)

Worledge, D.; Hinchcliffe, G.

1997-07-01

US nuclear plants are implementing preventive maintenance (PM) tasks with little documented basis beyond fundamental vendor information to support the tasks or their intervals. The Preventive Maintenance Basis project provides utilities with the technical basis for PM tasks and task intervals associated with 40 specific components such as valves, electric motors, pumps, and HVAC equipment. This report provides an overview of the PM Basis project and describes use of the PM Basis database. This volume 16 of the report provides a program of PM tasks suitable for application to power operated relief valves (PORV's) that are solenoid actuated. The PM tasks that are recommended provide a cost-effective way to intercept the causes and mechanisms that lead to degradation and failure. They can be used, in conjunction with material from other sources, to develop a complete PM program or to improve an existing program. Users of this information will be utility managers, supervisors, craft technicians, and training instructors responsible for developing, optimizing, or fine-tuning PM programs

Cryogenic Cam Butterfly Valve

Science.gov (United States)

McCormack, Kenneth J. (Inventor)

2016-01-01

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

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

Directory of Open Access Journals (Sweden)

Vivek Jitendra Panchal

2017-09-01

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

High-Compression-Ratio; Atkinson-Cycle Engine Using Low-Pressure Direct Injection and Pneumatic-Electronic Valve Actuation Enabled by Ionization Current and Foward-Backward Mass Air Flow Sensor Feedback

Energy Technology Data Exchange (ETDEWEB)

Harold Schock; Farhad Jaberi; Ahmed Naguib; Guoming Zhu; David Hung

2007-12-31

This report describes the work completed over a two and one half year effort sponsored by the US Department of Energy. The goal was to demonstrate the technology needed to produce a highly efficient engine enabled by several technologies which were to be developed in the course of the work. The technologies included: (1) A low-pressure direct injection system; (2) A mass air flow sensor which would measure the net airflow into the engine on a per cycle basis; (3) A feedback control system enabled by measuring ionization current signals from the spark plug gap; and (4) An infinitely variable cam actuation system based on a pneumatic-hydraulic valve actuation These developments were supplemented by the use of advanced large eddy simulations as well as evaluations of fuel air mixing using the KIVA and WAVE models. The simulations were accompanied by experimental verification when possible. In this effort a solid base has been established for continued development of the advanced engine concepts originally proposed. Due to problems with the valve actuation system a complete demonstration of the engine concept originally proposed was not possible. Some of the highlights that were accomplished during this effort are: (1) A forward-backward mass air flow sensor has been developed and a patent application for the device has been submitted. We are optimistic that this technology will have a particular application in variable valve timing direct injection systems for IC engines. (2) The biggest effort on this project has involved the development of the pneumatic-hydraulic valve actuation system. This system was originally purchased from Cargine, a Swedish supplier and is in the development stage. To date we have not been able to use the actuators to control the exhaust valves, although the actuators have been successfully employed to control the intake valves. The reason for this is the additional complication associated with variable back pressure on the exhaust valves when

A microfluidic control system with re-usable micropump/valve actuator and injection moulded disposable polymer lab-on-a-slide

DEFF Research Database (Denmark)

Bu, Minqiang; Perch-Nielsen, Ivan R.; Yi, Sun

2011-01-01

A microfluidic control system consisting of micropump/valves with a re-usable pneumatic actuator and a disposable polymer lab-on-a-slide is presented. The lab-on-a-slide was fabricated using low cost methods, such as injection moulding of TOPAS® cyclic olefin copolymer (COC) slide, lamination...... of different layers of polymer, and ultrasonic welding of TOPAS® lid to the slide. The re-usable pneumatic actuator not only simplifies the design of the lab-on-a-slide and reduces the fabrication cost, but also reduces the possibility of cross contamination during replacement of the disposable lab...

Valve monitoring ITI-MOVATS

International Nuclear Information System (INIS)

Moureau, S.

1993-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

VANDYKE, D.W.

1999-08-25

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

Pneumatic Variable Series Elastic Actuator.

Science.gov (United States)

Zheng, Hao; Wu, Molei; Shen, Xiangrong

2016-08-01

Inspired by human motor control theory, stiffness control is highly effective in manipulation and human-interactive tasks. The implementation of stiffness control in robotic systems, however, has largely been limited to closed-loop control, and suffers from multiple issues such as limited frequency range, potential instability, and lack of contribution to energy efficiency. Variable-stiffness actuator represents a better solution, but the current designs are complex, heavy, and bulky. The approach in this paper seeks to address these issues by using pneumatic actuator as a variable series elastic actuator (VSEA), leveraging the compressibility of the working fluid. In this work, a pneumatic actuator is modeled as an elastic element with controllable stiffness and equilibrium point, both of which are functions of air masses in the two chambers. As such, for the implementation of stiffness control in a robotic system, the desired stiffness/equilibrium point can be converted to the desired chamber air masses, and a predictive pressure control approach is developed to control the timing of valve switching to obtain the desired air mass while minimizing control action. Experimental results showed that the new approach in this paper requires less expensive hardware (on-off valve instead of proportional valve), causes less control action in implementation, and provides good control performance by leveraging the inherent dynamics of the actuator.

MEMS fluidic actuator

Science.gov (United States)

Kholwadwala, Deepesh K [Albuquerque, NM; Johnston, Gabriel A [Trophy Club, TX; Rohrer, Brandon R [Albuquerque, NM; Galambos, Paul C [Albuquerque, NM; Okandan, Murat [Albuquerque, NM

2007-07-24

The present invention comprises a novel, lightweight, massively parallel device comprising microelectromechanical (MEMS) fluidic actuators, to reconfigure the profile, of a surface. Each microfluidic actuator comprises an independent bladder that can act as both a sensor and an actuator. A MEMS sensor, and a MEMS valve within each microfluidic actuator, operate cooperatively to monitor the fluid within each bladder, and regulate the flow of the fluid entering and exiting each bladder. When adjacently spaced in a array, microfluidic actuators can create arbitrary surface profiles in response to a change in the operating environment of the surface. In an embodiment of the invention, the profile of an airfoil is controlled by independent extension and contraction of a plurality of actuators, that operate to displace a compliant cover.

Pump having pistons and valves made of electroactive actuators

Science.gov (United States)

Bar-Cohen, Yoseph (Inventor)

1997-01-01

The present invention provides a pump for inducing a displacement of a fluid from a first medium to a second medium, including a conduit coupled to the first and second media, a transducing material piston defining a pump chamber in the conduit and being transversely displaceable for increasing a volume of the chamber to extract the fluid from the first medium to the chamber and for decreasing the chamber volume to force the fluid from the chamber to the second medium, a first transducing material valve mounted in the conduit between the piston and the first medium and being transversely displaceable from a closed position to an open position to admit the fluid to the chamber, and control means for changing a first field applied to the piston to displace the piston for changing the chamber volume and for changing a second field applied to the first valve to change the position of the first valve.

Evaluation of Effective Diaphragm Area for Pneumatic Actuator

International Nuclear Information System (INIS)

Ryu, Hogeun; Han, Bongsub; Seon, Juhyoung

2016-01-01

The purpose of this study is to develop a methodology to calculate the exact effective diaphragm area using the results of diagnostic test to be performed in the evaluation of air operated valve performance. By using this developed methodology in pneumatic actuator performance evaluation, it can be reduce the possible errors arising from effective diaphragm area in the evaluation of performance of air operated valves. The performance assessment for the operability and structural integrity of air operated valves for the domestic nuclear power plant is in progress. One of the important parameters that determine the performance of the air operated valves is the effective diaphragm area of diaphragm type actuator. The effective diaphragm area is the actual area which the air pressure acting on the diaphragm. In general, the effective diaphragm area used for the performance evaluation of pneumatic actuator is provided by the manufacture or the actuator drawing. Flat type diaphragm was showed the difference between the measured value of EDA and the manufacture’s value, in the case of convoluted type diaphragm has showed that the measured value of EDA and manufacture’s value is almost the same. When evaluate a performance of a diaphragm actuator, accurate EDA is to be used because it is an important variable affecting the actuator performance. Particularly in the case of flat type diaphragm which EDA is changed in accordance with the stroke position, by using the EDA evaluation methodology developed in this study to minimize a possible error due to EDA when evaluating the performance of the air actuator

Evaluation of Effective Diaphragm Area for Pneumatic Actuator

Energy Technology Data Exchange (ETDEWEB)

Ryu, Hogeun; Han, Bongsub; Seon, Juhyoung [SOOSAN INDUSTRIES, Seoul (Korea, Republic of)

2016-10-15

The purpose of this study is to develop a methodology to calculate the exact effective diaphragm area using the results of diagnostic test to be performed in the evaluation of air operated valve performance. By using this developed methodology in pneumatic actuator performance evaluation, it can be reduce the possible errors arising from effective diaphragm area in the evaluation of performance of air operated valves. The performance assessment for the operability and structural integrity of air operated valves for the domestic nuclear power plant is in progress. One of the important parameters that determine the performance of the air operated valves is the effective diaphragm area of diaphragm type actuator. The effective diaphragm area is the actual area which the air pressure acting on the diaphragm. In general, the effective diaphragm area used for the performance evaluation of pneumatic actuator is provided by the manufacture or the actuator drawing. Flat type diaphragm was showed the difference between the measured value of EDA and the manufacture’s value, in the case of convoluted type diaphragm has showed that the measured value of EDA and manufacture’s value is almost the same. When evaluate a performance of a diaphragm actuator, accurate EDA is to be used because it is an important variable affecting the actuator performance. Particularly in the case of flat type diaphragm which EDA is changed in accordance with the stroke position, by using the EDA evaluation methodology developed in this study to minimize a possible error due to EDA when evaluating the performance of the air actuator.

Torsional fatigue model for limitorque type SMB/SB/SBD actuators for motor-operated valves

Energy Technology Data Exchange (ETDEWEB)

Somogyi, D.; Alvarez, P.D.; Kalsi, M.S. [Kalsi Engineering, Inc., Sugar Land, TX (United States)

1996-12-01

Kalsi Engineering, Inc. has recently developed a computer program to predict the torsional fatigue life of Limitorque Type SMB/SB/SBD actuators for motor-operated valves under given loading levels, including those that exceed the ratings. The development effort was an outgrowth of the {open_quote}Thrust Rating Increase{close_quote} test program. The fatigue model computes all pertinent stress components and their variations as a function of the loading ramp. The cumulative damage and fatigue life due to stress cycling is computed by use of a modification of Miner`s rule. Model predictions were validated against actual cyclic loading test results.

Torsional fatigue model for limitorque type SMB/SB/SBD actuators for motor-operated valves

International Nuclear Information System (INIS)

Somogyi, D.; Alvarez, P.D.; Kalsi, M.S.

1996-01-01

Kalsi Engineering, Inc. has recently developed a computer program to predict the torsional fatigue life of Limitorque Type SMB/SB/SBD actuators for motor-operated valves under given loading levels, including those that exceed the ratings. The development effort was an outgrowth of the open-quote Thrust Rating Increase close-quote test program. The fatigue model computes all pertinent stress components and their variations as a function of the loading ramp. The cumulative damage and fatigue life due to stress cycling is computed by use of a modification of Miner's rule. Model predictions were validated against actual cyclic loading test results

High speed hydraulically-actuated operating system for an electric circuit breaker

Science.gov (United States)

Iman, Imdad

1983-06-07

This hydraulically-actuated operating system comprises a cylinder, a piston movable therein in an opening direction to open a circuit breaker, and an accumulator for supplying pressurized liquid to a breaker-opening piston-actuating space within the cylinder. A normally-closed valve between the accumulator and the actuating space is openable to allow pressurized liquid from the accumulator to flow through the valve into the actuating space to drive the piston in an opening direction. A dashpotting mechanism operating separately from the hydraulic actuating system is provided, thereby reducing flow restriction interference with breaker opening.

A nuclear radiation actuated valve for a nuclear reactor

International Nuclear Information System (INIS)

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

1983-01-01

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

ADAM®/SIPLUG®: An innovative valve monitoring system

International Nuclear Information System (INIS)

Muñoz, L.; Krell, M.

2012-01-01

Optimized maintenance strategies are a key aspect for safe and undisturbed plant operation. Innovative valve service solutions, e.g. valve diagnostics can support this in an efficient way. The ADAM®/SIPLUG® valve monitoring system allows full online monitoring of valves and actuators with automatic evaluation and assessment. Especially for safety-related and operation-related valves this provides valuable information on components condition to ensure proper function and contribute to optimization of maintenance strategies as well as effective maintenance performance. The new SIPLUG®-4 modules are the evolutionary solution for valve diagnosis at the Motor Control Center (MCC). As the SIPLUG®-4 can be installed directly in the MCC outgoing actuator power cable it allows an easy installation in existing switchgear cabinets. Measurement at MCC means also zero effort for performance of diagnostics reducing the number of on-site activities. This results in decrease of maintenance costs and dose rates for deployed personnel. The ADAM® evaluation software and database was developed in parallel with the hardware. It provides automatic analysis of the monitoring results using the limit values specified for the valves. The measured data can be transmitted via the power plant’s local area network to the ADAM® data server, if the SIPLUG® online hardware is installed. With the mobile solution, the data can be transmitted via serial or USB interface to a PC or notebook. With this solution all measurement information will be available immediately in the offices of plant engineers. Also, with SIPLUG® online all operations of valves can be automatically recorded. More than 25 years of experience in various plants worldwide show that the application of ADAM®/SIPLUG® valve diagnostics solution leads to increased plant safety and availability. Some of the references for ADAM®/SIPLUG® are Germany, Switzerland, Brazil, Spain and Eastern Europe. (author)

A self-regulating valve for single-phase liquid cooling of microelectronics

International Nuclear Information System (INIS)

Donose, Radu; De Volder, Michaël; Peirs, Jan; Reynaerts, Dominiek

2011-01-01

This paper reports on the design, optimization and testing of a self-regulating valve for single-phase liquid cooling of microelectronics. Its purpose is to maintain the integrated circuit (IC) at constant temperature and to reduce power consumption by diminishing flow generated by the pump as a function of the cooling requirements. It uses a thermopneumatic actuation principle that combines the advantages of zero power consumption and small size in combination with a high flow rate and low manufacturing costs. The valve actuation is provided by the thermal expansion of a liquid (actuation fluid) which, at the same time, actuates the valve and provides feed-back sensing. A maximum flow rate of 38 kg h −1 passes through the valve for a heat load up to 500 W. The valve is able to reduce the pumping power by up to 60% and it has the capability to maintain the IC at a more uniform temperature.

Electrical actuators in a Chilean copper mine; Elektrische Stellantriebe in chilenischem Kupferbergwerk

Energy Technology Data Exchange (ETDEWEB)

Herbstritt, Michael [AUMA Riester GmbH und Co. KG, Muellheim (Germany)

2008-03-15

Mining of copper at the Los Pelambres mine in Chile yields a mixture of water, sand, sludge and mineral reminiscent of fresh concrete. This high-viscosity material is treated in a series of filters and sedimentation installations. The gate-type and other valves necessary for distribution are operated by the electrical actuator systems examined in this article. A special feature of this arrangement is the fact that the actuator itself is separated from the appurtenant local control system. Separate installation means that the actuator drive systems, which are mounted on mobile stands of 2 m height, can be easily parameterized. (orig.)

Piezoelectric valve for massive gas injection in ASDEX upgrade

Energy Technology Data Exchange (ETDEWEB)

Dibon, Mathias; Neu, Rudolf [Max-Planck-Institute for Plasmaphysics, Boltzmannstr. 2, 85748 Garching (Germany); Technical University Munich, Boltzmannstr. 15, 85748 Garching (Germany); Herrmann, Albrecht; Mank, Klaus; Mertens, Vitus; Pautasso, Gabriella; Ploeckl, Bernhard [Max-Planck-Institute for Plasmaphysics, Boltzmannstr. 2, 85748 Garching (Germany)

2016-07-01

A sudden loss of plasma temperature can cause a disruption, which poses a significant problem for current Tokamaks and future fusion devices. Hence, mitigating forces and thermal loads during disruptions is important for the integrity of the vessel and first wall components. Therefore, high speed gas valves are used to deliver a pulse of noble gas onto the plasma, which irradiates the thermal energy quickly, avoiding localized heat loads and mechanical stress due to induced currents. A new design for such a valve is currently under development. The valve plate is driven by two piezoelectric stack actuators. The stroke of the actuators (0.07 mm) is amplified by a monolithic titanium frame and reaches 2 mm. The frame also serves as spring to pre-load the actuators. In the idle state, it also presses the conical valve plate into the seal, closing the gas chamber (42 cm{sup 3}). The actuators accelerate the stem and the valve plate until it is fully opened after 2 ms. The orifice of the valve has a diameter of 14 mm. This allows a peak mass flow rate of the gas up to 8 . 10{sup 4} (Pa.m)/(s) after 1.8 ms and an average mass flow rate of 2 . 10{sup 4} (Pa.m)/(s) over the evacuation time of 10 ms. Therefore, one valve would be sufficient to deliver the required amount of gas to mitigate disruptions at ASDEX Upgrade.

Turbo-generator control with variable valve actuation

Science.gov (United States)

Vuk, Carl T [Denver, IA

2011-02-22

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

Enhancing roll stability of heavy vehicle by LQR active anti-roll bar control using electronic servo-valve hydraulic actuators

Science.gov (United States)

Vu, Van Tan; Sename, Olivier; Dugard, Luc; Gaspar, Peter

2017-09-01

Rollover of heavy vehicle is an important road safety problem world-wide. Although rollovers are relatively rare events, they are usually deadly accidents when they occur. The roll stability loss is the main cause of rollover accidents in which heavy vehicles are involved. In order to improve the roll stability, most of modern heavy vehicles are equipped with passive anti-roll bars to reduce roll motion during cornering or riding on uneven roads. However these may be not sufficient to overcome critical situations. This paper introduces the active anti-roll bars made of four electronic servo-valve hydraulic actuators, which are modelled and integrated in a yaw-roll model of a single unit heavy vehicle. The control signal is the current entering the electronic servo-valve and the output is the force generated by the hydraulic actuator. The active control design is achieved solving a linear optimal control problem based on the linear quadratic regulator (LQR) approach. A comparison of several LQR controllers is provided to allow for tackling the considered multi-objective problems. Simulation results in frequency and time domains show that the use of two active anti-roll bars (front and rear axles) drastically improves the roll stability of the single unit heavy vehicle compared with the passive anti-roll bar.

Sensor-integrated polymer actuators for closed-loop drug delivery system

Science.gov (United States)

Xu, Han; Wang, Chunlei; Kulinsky, Lawrence; Zoval, Jim; Madou, Marc

2006-03-01

This work presents manufacturing and testing of a closed-loop drug delivery system where drug release is achieved by an electrochemical actuation of an array of polymeric valves on a set of drug reservoirs. The valves are based on bi-layer structures made of polypyrrole/gold in the shape of a flap that is hinged on one side of a valve seat. Drugs stored in the underlying chambers are released by bending the bi-layer flaps back with a small applied bias. These polymeric valves simultaneously function as both drug release components and biological/chemical sensors responding to a specific biological or environmental stimulus. The sensors may send signals to the control module to realize closed-loop control of the drug release. In this study a glucose sensor has been integrated with the polymeric actuators through immobilization of glucose oxidase(GOx) within polypyrrole(PPy) valves. Sensitivities per unit area of the integrated glucose sensor have been measured and compared before and after the actuation of the sensor/actuator PPy/DBS/GOx film. Other sensing parameters such as linear range and response time were discussed as well. Using an array of these sensor/actuator cells, the amount of released drug, e.g. insulin, can be precisely controlled according to the surrounding glucose concentration detected by the glucose sensor. Activation of these reservoirs can be triggered either by the signal from the sensor, or by the signal from the operator. This approach also serves as the initial step to use the proposed system as an implantable drug delivery platform in the future.

The SNS Resonance Control Cooling System Control Valve Upgrade Performance

International Nuclear Information System (INIS)

Williams, Derrick C.; Schubert, James Phillip; Tang, Johnny Y.

2008-01-01

The normal-conducting linac of the Spallation Neutron Source (SNS) uses 10 separate Resonance Control Cooling System (RCCS) water skids to control the resonance of 6 Drift Tube Linac (DTL) and 4 Coupled Cavity Linac (CCL) accelerating structures. The RCCS water skids use 2 control valves; one to regulate the chilled water flow and the other to bypass water to a chilled water heat exchanger. These valves have hydraulic actuators that provide position and feedback to the control system. Frequency oscillations occur using these hydraulic actuators due to their coarse movement and control of the valves. New pneumatic actuator and control positioners have been installed on the DTL3 RCCS water skid to give finer control and regulation of DTL3 cavity temperature. This paper shows a comparison of resonance control performance for the two valve configurations.

Electrical servo actuator bracket. [fuel control valves on jet engines

Science.gov (United States)

Sawyer, R. V. (Inventor)

1981-01-01

An electrical servo actuator is mounted on a support arm which is allowed to pivot on a bolt through a fixed mounting bracket. The actuator is pivotally connected to the end of the support arm by a bolt which has an extension allowed to pass through a slot in the fixed mounting bracket. An actuator rod extends from the servo actuator to a crank arm which turns a control shaft. A short linear thrust of the rod pivots the crank arm through about 90 for full-on control with the rod contracted into the servo actuator, and full-off control when the rod is extended from the actuator. A spring moves the servo actuator and actuator rod toward the control crank arm once the actuator rod is fully extended in the full-off position. This assures the turning of the control shaft to a full-off position. A stop bolt and slot are provided to limit pivot motion. Once fully extended, the spring pivots the motion.

Shuttle Primary Reaction Control Subsystem Thruster Fuel Valve Pilot Seal Extrusion: A Failure Correlation

Science.gov (United States)

Waller, Jess; Saulsberry, Regor L.

2003-01-01

Pilot operated valves (POVs) are used to control the flow of hypergolic propellants monomethylhydrazine (fuel) and nitrogen tetroxide (oxidizer) to the Shuttle orbiter Primary Reaction Control Subsystem (PRCS) thrusters. The POV incorporates a two-stage design: a solenoid-actuated pilot stage, which in turn controls a pressure-actuated main stage. Isolation of propellant supply from the thruster chamber is accomplished in part by a captive polytetrafluoroethylene (PTFE) pilot seal retained inside a Custom 455.1 stainless steel cavity. Extrusion of the pilot seal restricts the flow of fuel around the pilot poppet, thus impeding or preventing the main valve stage from opening. It can also prevent the main stage from staying open with adequate force margin, particularly if there is gas in the main stage actuation cavity. During thruster operation on-orbit, fuel valve pilot seal extrusion is commonly indicated by low or erratic chamber pressure or failure of the thruster to fire upon command (Fail-Off). During ground turnaround, pilot seal extrusion is commonly indicated by slow gaseous nitrogen (GN2) main valve opening times (greater than 38 ms) or slow water main valve opening response times (greater than 33 ms). Poppet lift tests and visual inspection can also detect pilot seal extrusion during ground servicing; however, direct metrology on the pilot seat assembly provides the most quantitative and accurate means of identifying extrusion. Minimizing PRCS fuel valve pilot seal extrusion has become an important issue in the effort to improve PRCS reliability and reduce associated life cycle costs.

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

International Nuclear Information System (INIS)

Park, Sung Hwan

2009-01-01

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

Enhancement of pressurizer safety valve operability by seating design improvement

International Nuclear Information System (INIS)

Moisidis, N.T.; Ratiu, M.D.

1995-01-01

Operating conditions specific to pressurizer safety valves (PSVs) have led to numerous problems and have caused industry and NRC concerns regarding the adequacy of spring-loaded self-actuated safety valves for reactor coolant system (RCS) overpressure protection. Specific concerns are: setpoint drift, spurious actuations, and pressure protection. Specific concerns are: setpoint drift, spurious actuations, and leakage. Based on testing and valve construction analysis of a Crosby model 6M6 PSV (Moisidis and Ratiu, 1992), it was established that the primary contributor to the valve problems is a susceptibility to weak seating. To eliminate spring instability, a new spring washer was designed, which guides the spring and precludes its rotation from the reference installed position. Results of tests performed on a prototype PSV equipped with the modified upper spring washer has shown significant improvements in valve operability and a consistent setpoint reproducibility to less than ±1% of the PSV setpoint (testing of baseline, unmodified valve, resulted in a setpoint drift of ± 2%). Enhanced valve operability will result in a significant decrease in operating and maintenance costs associated with valve maintenance and testing. In addition, the enhanced setpoint reproducibility will allow the development of a nitrogen to steam correlation for future in-house PSV testing which will result in further reductions in costs associated with valve testing

An Approach to the Prototyping of an Optimized Limited Stroke Actuator to Drive a Low Pressure Exhaust Gas Recirculation Valve.

Science.gov (United States)

Gutfrind, Christophe; Dufour, Laurent; Liebart, Vincent; Vannier, Jean-Claude; Vidal, Pierre

2016-05-20

The purpose of this article is to describe the design of a limited stroke actuator and the corresponding prototype to drive a Low Pressure (LP) Exhaust Gas Recirculation (EGR) valve for use in Internal Combustion Engines (ICEs). The direct drive actuator topology is an axial flux machine with two air gaps in order to minimize the rotor inertia and a bipolar surface-mounted permanent magnet in order to respect an 80° angular stroke. Firstly, the actuator will be described and optimized under constraints of a 150 ms time response, a 0.363 N·m minimal torque on an angular range from 0° to 80° and prototyping constraints. Secondly, the finite element method (FEM) using the FLUX-3D(®) software (CEDRAT, Meylan, France) will be used to check the actuator performances with consideration of the nonlinear effect of the iron material. Thirdly, a prototype will be made and characterized to compare its measurement results with the analytical model and the FEM model results. With these electromechanical behavior measurements, a numerical model is created with Simulink(®) in order to simulate an EGR system with this direct drive actuator under all operating conditions. Last but not least, the energy consumption of this machine will be estimated to evaluate the efficiency of the proposed EGR electromechanical system.

An Approach to the Prototyping of an Optimized Limited Stroke Actuator to Drive a Low Pressure Exhaust Gas Recirculation Valve

Science.gov (United States)

Gutfrind, Christophe; Dufour, Laurent; Liebart, Vincent; Vannier, Jean-Claude; Vidal, Pierre

2016-01-01

The purpose of this article is to describe the design of a limited stroke actuator and the corresponding prototype to drive a Low Pressure (LP) Exhaust Gas Recirculation (EGR) valve for use in Internal Combustion Engines (ICEs). The direct drive actuator topology is an axial flux machine with two air gaps in order to minimize the rotor inertia and a bipolar surface-mounted permanent magnet in order to respect an 80° angular stroke. Firstly, the actuator will be described and optimized under constraints of a 150 ms time response, a 0.363 N·m minimal torque on an angular range from 0° to 80° and prototyping constraints. Secondly, the finite element method (FEM) using the FLUX-3D® software (CEDRAT, Meylan, France) will be used to check the actuator performances with consideration of the nonlinear effect of the iron material. Thirdly, a prototype will be made and characterized to compare its measurement results with the analytical model and the FEM model results. With these electromechanical behavior measurements, a numerical model is created with Simulink® in order to simulate an EGR system with this direct drive actuator under all operating conditions. Last but not least, the energy consumption of this machine will be estimated to evaluate the efficiency of the proposed EGR electromechanical system. PMID:27213398

Nonlinear dynamic modeling for smart material electro-hydraulic actuator development

Science.gov (United States)

Larson, John P.; Dapino, Marcelo J.

2013-03-01

Smart material electro-hydraulic actuators use hydraulic rectification by one-way check valves to amplify the motion of smart materials, such as magnetostrictives and piezoelectrics, in order to create compact, lightweight actuators. A piston pump driven by a smart material is combined with a hydraulic cylinder to form a self-contained, power-by-wire actuator that can be used in place of a conventional hydraulic system without the need for hydraulic lines and a centralized pump. The performance of an experimental actuator driven by a 12.7 mm diameter, 114 mm length Terfenol-D rod is evaluated over a range of applied input frequencies, loads, and currents. The peak performance achieved is 37 W, moving a 220 N load at a rate of 17 cm/s and producing a blocked pressure of 12.5 MPa. Additional tests are conducted to quantify the dynamic behavior of the one-way reed valves using a scanning laser vibrometer to identify the frequency response of the reeds and the effect of the valve seat and fluid mass loading. A lumped-parameter model is developed for the system that includes valve inertia and fluid response nonlinearities, and the model results are compared with the experimental data.

Design of pneumatic proportional flow valve type 5/3

Science.gov (United States)

Laski, P. A.; Pietrala, D. S.; Zwierzchowski, J.; Czarnogorski, K.

2017-08-01

In this paper the 5/3-way pneumatic, proportional flow valve was designed and made. Stepper linear actuator was used to move the spool. The valve is controlled by the controlled based on a AVR microcontroller. Virtual model of the valve was created in CAD. The real element was made based on a standard 5/3-way manually actuated valve with hand lever, which was dismounted and replaced by linear stepper motor. All the elements was mounted in a specially made housing. The controller consists of microcontroller Atmega16, integrated circuit L293D, display, two potentiometers, three LEDs and six buttons. Series of research was also conducted. Simulation research were performed using CFD by the Flow Simulation addition to SolidWorks. During the experiments the valve characteristics of flow and pressure was determined.

An Unconventional Inchworm Actuator Based on PZT/ERFs Control Technology.

Science.gov (United States)

Liu, Guojun; Zhang, Yanyan; Liu, Jianfang; Li, Jianqiao; Tang, Chunxiu; Wang, Tengfei; Yang, Xuhao

2016-01-01

An unconventional inchworm actuator for precision positioning based on piezoelectric (PZT) actuation and electrorheological fluids (ERFs) control technology is presented. The actuator consists of actuation unit (PZT stack pump), fluid control unit (ERFs valve), and execution unit (hydraulic actuator). In view of smaller deformation of PZT stack, a new structure is designed for actuation unit, which integrates the advantages of two modes (namely, diaphragm type and piston type) of the volume changing of pump chamber. In order to improve the static shear yield strength of ERFs, a composite ERFs valve is designed, which adopts the series-parallel plate compound structure. The prototype of the inchworm actuator has been designed and manufactured in the lab. Systematic test results indicate that the displacement resolution of the unconventional inchworm actuator reaches 0.038 μm, and the maximum driving force and velocity are 42 N, 14.8 mm/s, respectively. The optimal working frequency for the maximum driving velocity is 120 Hz. The complete research and development processes further confirm the feasibility of developing a new type of inchworm actuator with high performance based on PZT actuation and ERFs control technology, which provides a reference for the future development of a new type of actuator.

An Unconventional Inchworm Actuator Based on PZT/ERFs Control Technology

Directory of Open Access Journals (Sweden)

Guojun Liu

2016-01-01

Full Text Available An unconventional inchworm actuator for precision positioning based on piezoelectric (PZT actuation and electrorheological fluids (ERFs control technology is presented. The actuator consists of actuation unit (PZT stack pump, fluid control unit (ERFs valve, and execution unit (hydraulic actuator. In view of smaller deformation of PZT stack, a new structure is designed for actuation unit, which integrates the advantages of two modes (namely, diaphragm type and piston type of the volume changing of pump chamber. In order to improve the static shear yield strength of ERFs, a composite ERFs valve is designed, which adopts the series-parallel plate compound structure. The prototype of the inchworm actuator has been designed and manufactured in the lab. Systematic test results indicate that the displacement resolution of the unconventional inchworm actuator reaches 0.038 μm, and the maximum driving force and velocity are 42 N, 14.8 mm/s, respectively. The optimal working frequency for the maximum driving velocity is 120 Hz. The complete research and development processes further confirm the feasibility of developing a new type of inchworm actuator with high performance based on PZT actuation and ERFs control technology, which provides a reference for the future development of a new type of actuator.

Valve performance concept move from preventive to condition-oriented maintenance

International Nuclear Information System (INIS)

Zanner, G.; Kradepohl, P.

1996-01-01

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

Valve performance concept move from preventive to condition-oriented maintenance

Energy Technology Data Exchange (ETDEWEB)

Zanner, G.; Kradepohl, P.

1996-12-01

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

On-demand liquid-in-liquid droplet metering and fusion utilizing pneumatically actuated membrane valves

International Nuclear Information System (INIS)

Lin, Bo-Chih; Su, Yu-Chuan

2008-01-01

This paper presents an active emulsification scheme that is capable of producing micro-droplets with desired volumes and compositions on demand. Devices with pneumatically actuated membranes constructed on top of specially designed microfluidic channels are utilized to meter and fuse liquid-in-liquid droplets. By steadily pressurizing a fluid and intermittently blocking its flow, droplets with desired volumes are dispersed into another fluid. Furthermore, droplets from multiple sources are fused together to produce combined droplets with desired compositions. In the prototype demonstration, a three-layer PDMS molding and irreversible bonding process was employed to fabricate the proposed microfluidic devices. For a dispersed-phase flow that is normally blocked by a membrane valve, the relationship between the volume (V) of a metered droplet and the corresponding valve open time (T) is found to be approximately V = kT a , in which k and a are constants determined mainly by the fluid-driving pressures. In addition to the metering device, functional droplet entrapment, fusion and flow-switching devices were also integrated in the system to produce desired combined droplets and deliver them to intended destinations upon request. As such, the demonstrated microfluidic system could potentially realize the controllability on droplet volume, composition and motion, which is desired for a variety of chemical and biological applications

Piezoelectric-hydraulic pump based band brake actuation system for automotive transmission control

Science.gov (United States)

Kim, Gi-Woo; Wang, K. W.

2007-04-01

The actuation system of friction elements (such as band brakes) is essential for high quality operations in modern automotive automatic transmissions (in short, ATs). The current band brake actuation system consists of several hydraulic components, including the oil pump, the regulating valve and the control valves. In general, it has been recognized that the current AT band brake actuation system has many limitations. For example, the oil pump and valve body are relatively heavy and complex. Also, the oil pumps induce inherently large drag torque, which affects fuel economy. This research is to overcome these problems of the current system by exploring the utilization of a hybrid type piezo-hydraulic pump device for AT band brake control. This new actuating system integrates a piezo-hydraulic pump to the input of the band brake. Compared with the current systems, this new actuator features much simpler structure, smaller size, and lower weight. This paper describes the development, design and fabrication of the new stand-alone prototype actuator for AT band brake control. An analytical model is developed and validated using experimental data. Performance tests on the hardware and system simulations utilizing the validated model are performed to characterize the new prototype actuator. It is predicted that with increasing of accumulator pressure and driving frequency, the proposed prototype actuating system will satisfy the band brake requirement for AT shift control.

Optothermally actuated capillary burst valve

DEFF Research Database (Denmark)

Eriksen, Johan; Bilenberg, Brian; Kristensen, Anders

2017-01-01

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

An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

International Nuclear Information System (INIS)

Jung, Wooseok; Barrett, Matthew; Brooks, Carla; Zenhausern, Frederic; Rivera, Andrew; Birdsell, Dawn N; Wagner, David M

2015-01-01

We present a new elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis. The valve functions include metering to capture a designated volume of biological sample into a polymerase chain reaction (PCR) chamber, sealing to preserve the sample during PCR cycling, and transfer of the PCR-products and on-chip formamide post-processing for the analysis of DNA fragments by capillary gel electrophoresis. This new valve differs from prior art polydimethylsiloxane (PDMS) valves in that the valve is not actuated externally by air-pressure or vacuum so that it simplifies a DNA analysis system by eliminating the need for an air-pressure or vacuum source, and off-cartridge solenoid valves, control circuit boards and software. Instead, the new valve is actuated by a thermal cycling peltier assembly integrated within the hardware instrument that tightly comes in contact with a microfluidic cartridge for thermal activation during PCR, so that it spontaneously closes the valve without an additional actuator system. The valve has bumps in the designated locations so that it has a self-alignment that does not require precise alignment of a valve actuator. Moreover, the thickness of the new valve is around 600 μm with an additional bump height of 400 μm so that it is easy to handle and very feasible to fabricate by injection molding compared to other PDMS valves whose thicknesses are around 30–100 μm. The new valve provided over 95% of metering performance in filling the fixed volume of the PCR chamber, preserved over 97% of the sample volume during PCR, and showed very comparable capillary electrophoresis peak heights to the benchtop assay tube controls with very consistent transfer volume of the PCR-product and on-chip formamide. The new valve can perform a core function for integrated nucleic acid analysis by capillary electrophoresis. (paper)

Investigation on the Effects of Internal EGR by Variable Exhaust Valve Actuation with Post Injection on Auto-ignited Combustion and Emission Performance

Directory of Open Access Journals (Sweden)

Insu Cho

2018-04-01

Full Text Available Variable valve mechanisms are usually applied to a gasoline combustion engine to improve its power performance by controlling the amount of intake air according to the operating load. These mechanisms offer one possibility of resolving the conflict of objectives between a further reduction of raw emissions and an improvement in fuel efficiency. In recent years, variable valve control systems have become extremely important in the diesel combustion engine. Importantly, it has been shown that there are several potential benefits of applying variable valve timing (VVT to a compression ignition engine. Valve train variability could offer one option to achieve the reduction goals of engine-out emissions and fuel consumption. The aim of this study was to investigate the effects on part load combustion and emission performance of internal exhaust gas recirculation (EGR by variable exhaust valve lift actuation using a cam-in-cam system, which is an electronically variable valve device with a variable inside cam retarded to about 30 degrees. Numerical simulation based on GT-POWER has been performed to predict the NOx reduction strategy at the part load operating point of 1200 rpm in a four-valve diesel engine. A GT-POWER model of a common-rail direct injection engine with internal EGR was built and verified with experimental data. As a result, large potential for reducing NOx emissions through the use of exhaust valve control has been identified. Namely, it is possible to utilize heat efficiently as recompression of retarded post injection with downscaled specification of the exhaust valve rather than the intake valve, even if the CIC V1 condition with a reduction of the exhaust valve has a higher internal EGR rate of about 2% compared to that of the CIC V2 condition.

LOFT pressurizer safety: relief valve reliability

Energy Technology Data Exchange (ETDEWEB)

Brown, E.S.

1978-01-18

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

LOFT pressurizer safety: relief valve reliability

International Nuclear Information System (INIS)

Brown, E.S.

1978-01-01

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

CFD simulation on flow induced vibrations in high pressure control and emergency stop turbine valve

International Nuclear Information System (INIS)

Lindqvist, H.

2011-01-01

During the refuelling outage at Unit 2 of Forsmark NPP in 2009, the high pressure turbine valves were replaced. Three month after recommissioning, an oil pipe connected to one of the actuators was broken. Measurements showed high-frequency vibration levels. The pipe break was suspected to be an effect of highly increased vibrations caused by the new valve. In order to establish the origin of the vibrations, investigations by means of CFD-simulations were made. The simulations showed that the increased vibrations most likely stems from the open cavity that the valves centre consists of. (author)

Osmotic actuation for microfluidic components in point-of-care applications

KAUST Repository

Chen, Yu-Chih; Ingram, Patrick; Lou, Xia; Yoon, Euisik

2013-01-01

at low cost. In this work, we report two key active components actuated by osmotic mechanism for total integrated microfluidic system. For the proof of concept, we have demonstrated valve actuation, which can maintain stable ON/OFF switching operations

Development of advanced diagnostic technologies for motor-operated valves

International Nuclear Information System (INIS)

Hegi, Kotaro; Shimizu, Shunichi; Higuma, Koji; Nishino, Koji; Osaki, Kenji; Watanabe, Kazumi; Hamano, Frank

2010-01-01

As use of condition-based maintenance is allowed in the new regulatory inspection system employed in Japan's nuclear power plants in 2009, development of advanced diagnostic technologies for motor-operated valves (MOVs) is now required. This report discusses advanced technologies in valve-setup verification, valve performance evaluation, monitoring of valve/actuator conditions by performance diagnostic system and moreover detection of stem crack by ultrasonic diagnostic system. (author)

Self-actuating and locking control for nuclear reactor

International Nuclear Information System (INIS)

Chung, D.K.

1982-01-01

A self-actuating, self-locking flow cutoff valve particularly suited for use in a nuclear reactor of the type which utilizes a plurality of fluid support neutron absorber elements to provide for the safe shutdown of the reactor. The valve comprises a substantially vertical elongated housing and an aperture plate located in the housing for the flow of fluid therethrough, a substantially vertical elongated nozzle member located in the housing and affixed to the housing with an opening in the bottom for receiving fluid and apertures adjacent a top end for discharging fluid. The nozzle further includes two sealing means, one located above and the other below the apertures. Also located in the housing and having walls surrounding the nozzle is a flow cutoff sleeve having a fluid opening adjacent an upper end of the sleeve, the sleeve being moveable between an upper open position wherein the nozzle apertures are substantially unobstructed and a closed position wherein the sleeve and nozzle sealing surfaces are mated such that the flow of fluid through the apertures is obstructed. It is a particular feature of the present invention that the valve further includes a means for utilizing any increase in fluid pressure to maintain the cutoff sleeve in a closed position. It is another feature of the invention that there is provided a means for automatically closing the valve whenever the flow of fluid drops below a predetermined level

Leakage characterization of a piloted power operated relief valve

International Nuclear Information System (INIS)

Ezekoye, L.I.; Hess, M.D.

1995-01-01

In Westinghouse Pressurized Water Reactors (PWRs), power operated relief valves (PORVs) are used to provide overpressure protection of the Pressurizer. The valves are fail closed globe valves which means that power is required to open the valves and, on loss of power, the valves close. There are two ways to operate the PORVs. The more common way is to directly couple the disc to an actuator via a disc-stem assembly. The type of design is not the object of this paper. The other and less common way of operating a PORV is by piloting the main valve such that the opening or closing of a pilot valve opens and closes the main valve. This is the design of interest. In most plants, the PORVs are installed with a water loop seal while in some plants no water loop seals are used. It is generally accepted that loop seal installation minimizes valve seat leakage. In non-loop seal installation, the valve seat is exposed to steam which increases the potential for seat leakage. This paper describes the results of some tests performed with nitrogen and steam to characterize the leakage potential of a pilot operated PORV. The test results were compared with seat leakage tests of check valves to provide insight on the leakage testing of pilot operated valves and check valves. The paper also compares the test data with leakage estimates using the ASME/ANSI OM Code guidance on valve leakage

Effects of aging and service wear on main steam isolation valves and valve operators

International Nuclear Information System (INIS)

Clark, R.L.

1996-03-01

In recent years main steam isolation valve (MSIV operating problems have resulted in significant operational transients (e.g., spurious reactor trips, steam generator dry out, excessive valve seat leakage), increased cost, and decreased plant availability. A key ingredient to an engineering-oriented reliability improvement effort is a thorough understanding of relevant historical experience. A detailed review of historical failure data available through the Institute of Nuclear Power Operation's Nuclear Plant Reliability Data System has been conducted for several types of MSIVs and valve operators for both boiling-water reactors and pressurized-water reactors. The focus of this review is on MSIV failures modes, actuator failure modes, consequences of failure on plant operations, method of failure detection, and major stressors affecting both valves and valve operators

Non-linear control of a hydraulic piezo-valve using a generalized Prandtl-Ishlinskii hysteresis model

OpenAIRE

Stefanski, Frederik; Minorowicz, Bartosz; Persson, Johan; Plummer, Andrew; Bowen, Christopher

2017-01-01

The potential to actuate proportional flow control valves using piezoelectric ceramics or other smart materials has been investigated for a number of years. Although performance advantages compared to electromagnetic actuation have been demonstrated, a major obstacle has proven to be ferroelectric hysteresis, which is typically 20% for a piezoelectric actuator. In this paper, a detailed study of valve control methods incorporating hysteresis compensation is made for the first time. Experiment...

Design of a MRI-compatible dielectric elastomer powered jet valve

Science.gov (United States)

Proulx, Sylvain; Chouinard, Patrick; Lucking Bigue, Jean-Philippe; Miron, Geneviève; Plante, Jean-Sébastien

2011-04-01

Binary Pneumatic Air Muscles (PAM) arranged in an elastically-averaged configuration can form a cost effective solution for Magnetic Resonance Imaging (MRI) guided robotic interventions like prostate cancer biopsies and brachytherapies. Such binary pneumatic manipulators require about 10 to 20 MRI-compatible valves to control the pressure state of each PAM. In this perspective, this paper presents the design of a novel dielectric elastomer actuator (DEA) driven jet-valve to control the states of the PAMs. DEAs are MRI compatible actuators that are well suited to the simplicity and cost-effectiveness of the binary manipulation approach. The key feature of the proposed valve design is its 2 stages configuration in which the pilot stage is moved with minimal mechanical friction by a rotary antagonistic DEA made with acrylic polymer films. The prismatic geometry also integrates the jet nozzle within the DEA volume to provide a compact embodiment with a reduced number of parts. The low actuation stretches enabled by the rotary configuration minimize viscoelastic losses, and thus, maximize the frequency response of the actuator while maximizing its reliability potential. The design space of the proposed jet valve is studied using an Ogden hyperelastic model and the valve dynamics is predicted with a 1D Bergstrom-Boyce viscoelastic model. Altogether, the low friction of the pilot stage and optimized DEA dynamics provide an experimental shifting time of the complete assembly in the 200-300ms range. Results from this work suggest that the DEA driven jet valve has great potential for switching a large number of pneumatic circuits in a MRI environment with a compact, low cost and simple embodiment.

A review of design and modeling of magnetorheological valve

Science.gov (United States)

Abd Fatah, Abdul Yasser; Mazlan, Saiful Amri; Koga, Tsuyoshi; Zamzuri, Hairi; Zeinali, Mohammadjavad; Imaduddin, Fitrian

2015-01-01

Following recent rapid development of researches in utilizing Magnetorheological (MR) fluid, a smart material that can be magnetically controlled to change its apparent viscosity instantaneously, a lot of applications have been established to exploit the benefits and advantages of using the MR fluid. One of the most important applications for MR fluid in devices is the MR valve, where it uses the popular flow or valve mode among the available working modes for MR fluid. As such, MR valve is widely applied in a lot of hydraulic actuation and vibration reduction devices, among them are dampers, actuators and shock absorbers. This paper presents a review on MR valve, discusses on several design configurations and the mathematical modeling for the MR valve. Therefore, this review paper classifies the MR valve based on the coil configuration and geometrical arrangement of the valve, and focusing on four different mathematical models for MR valve: Bingham plastic, Herschel-Bulkley, bi-viscous and Herschel-Bulkley with pre-yield viscosity (HBPV) models for calculating yield stress and pressure drop in the MR valve. Design challenges and opportunities for application of MR fluid and MR valve are also highlighted in this review. Hopefully, this review paper can provide basic knowledge on design and modeling of MR valve, complementing other reviews on MR fluid, its applications and technologies.

Integral isolation valve systems for loss of coolant accident protection

Science.gov (United States)

Kanuch, David J.; DiFilipo, Paul P.

2018-03-20

A nuclear reactor includes a nuclear reactor core comprising fissile material disposed in a reactor pressure vessel having vessel penetrations that exclusively carry flow into the nuclear reactor and at least one vessel penetration that carries flow out of the nuclear reactor. An integral isolation valve (IIV) system includes passive IIVs each comprising a check valve built into a forged flange and not including an actuator, and one or more active IIVs each comprising an active valve built into a forged flange and including an actuator. Each vessel penetration exclusively carrying flow into the nuclear reactor is protected by a passive IIV whose forged flange is directly connected to the vessel penetration. Each vessel penetration carrying flow out of the nuclear reactor is protected by an active IIV whose forged flange is directly connected to the vessel penetration. Each active valve may be a normally closed valve.

Studies to demonstrate the adequacy of testing results of the qualification tests for the actuator of main steam safety relive valves (MSSRV) in an advanced boiling water reactor (ABWR)

International Nuclear Information System (INIS)

Gou, P.F.; Patel, R.; Curran, G.; Henrie, D.; Solorzano, E.

2005-01-01

This paper presents several studies performed to demonstrate that the testing results from the qualification tests for the actuator of the Main Steam Safety Relief Valves (MSSRV; also called SRV in this paper) in GE's Advanced Boiling Water Reactor (ABWR) are in compliance with the qualification guidelines stipulated in the applicable IEEE standards. The safety-related function of the MSSRV is to relieve pressure in order to protect the reactor pressure vessel from over-pressurization condition during normal operation and design basis events. In order to perform this function, the SRV must actuate at a given set pressure while maintaining the pressure and structural integrity of the SRV. The valves are provided with an electro-pneumatic actuator assembly that opens the valve upon receipt of an automatic or manually initiated electric signal to allow depressurization of the reactor pressure vessel (RPV). To assure the SRV can perform its intended safety related functions properly, qualification tests are needed in addition to analysis, to demonstrate that the SRV can withstand the specified environmental, dynamic and seismic design basis conditions without impairing its safety related function throughout their installed life under the design conditions including postulated design basis events such as OBE loads and Faulted (SSE) events. The guidelines used for the test methods, procedures and acceptance criteria for the qualification tests are established in IEEE std 344-1987 and IEEE std 382-1985. In the qualification tests, the specimen consists of the actuator, control valve assembly, limit switches, and limit switch support structure. During the functional, dynamic and seismic tests, the test specimen was mounted on a SRV. Qualification of safety related equipment to meet the guidelines of the IEEE standards is typically a two-step process: 1) environmental aging and 2) design basis events qualification. The purpose of the first step is to put the equipment in an

NRC Information No. 90-21: Potential failure of motor-operated butterfly valves to operate because valve seat friction was underestimated

International Nuclear Information System (INIS)

Rossi, C.E.

1992-01-01

In October 1988, at Catawba Nuclear Station Unit 1, a motor-operated butterfly valve in the service water system failed to open under high differential pressure conditions. The licensee concluded that the valve manufacturer, BIF/General Signal Corporation, had underestimated the degree to which the material used in the valve seat would harden with age (the responsibility for these valves has been transferred to Paul-Munroe Enertech). This underestimation of the age hardening had led the manufacturer to assume valve seat friction forces that were less than the actual friction forces in the installed valve. To overcome the larger-than-anticipated friction forces, the licensee's engineering staff recommended the open torque switch for 56 butterfly valves be reset to the maximum allowable value. The systems in which these valves are located include the component cooling water system, service water system, and various ventilation systems. By July 26, 1989, the torque switch adjustments were completed at Catawba Units 1 and 2. After reviewing the final settings, the licensee's engineering staff determined that the actuators for three butterfly valves in the component cooling water system might not be able to overcome the friction forces resulting from maximum seat hardening. On December 13, 1989, the licensee determined that the failure of these BIF/General Signal motor-operated valves (MOVs) could cause a loss of cooling water to residual heat removal system heat exchangers. To resolve the concern regarding the operability of these BIF/General Signal valves, a torque switch bypass was installed on two of the actuators to allow full motor capability during opening

Fabrication of micro metallic valve and pump

Science.gov (United States)

Yang, Ming; Kabasawa, Yasunari; Ito, Kuniyoshi

2010-03-01

Fabrication of micro devices by using micro metal forming was proposed by the authors. We developed a desktop servo-press machine with precise tooling system. Precise press forming processes including micro forging and micro joining has been carried out in a progressive die. In this study, micro metallic valve and pump were fabricated by using the precise press forming. The components are made of sheet metals, and assembled in to a unit in the progressive die. A micro check-valve with a diameter of 3mm and a length of 3.2mm was fabricated, and the property of flow resistance was evaluated. The results show that the check valve has high property of leakage proof. Since the valve is a unit parts with dimensions of several millimeters, it has advantage to be adapted to various pump design. Here, two kinds of micro pumps with the check-valves were fabricated. One is diaphragm pump actuated by vibration of the diaphragm, and another is tube-shaped pump actuated by resonation. The flow quantities of the pumps were evaluated and the results show that both of the pumps have high pumping performance.

Indigeneous design and development of differential pressure reducing valves for PHWRs (Paper No. 055)

International Nuclear Information System (INIS)

Soni, N.L.; Agrawal, R.C.; Chandra, Rajesh

1987-02-01

On load fuelling of Pressurised Heavy Water Reactors (PHWRs) is being achieved with the help of Fuelling Machine (F/M). Various actuations are to be carried out inside the F/M magazine pressure housing with the help of high pressure water hydraulic actuators. A constant differential pressure is required to be maintained between pressurized magazine housing and the actuators-supply line for proper operation of the actuators which are to be located inside it. This is achieved with the help of the Differential Pressure Reducing Valve (DPRV). So far these valves have been procured only from a single foreign supplier. In March 1980, the price of each valve was US dollars 3100.00. Dependence on a single foreign supplier may create problems of timely procurement. An effort was made to design and manufacture the DPRV indigensouly meeting the stringent specifications. Theoretical study of single acting DPRV was carried out and design criteria were established. The valve was tested for its performance and was found satisfactory. (author). 8 figs

Design, fabrication and characterization of an arrayable all-polymer microfluidic valve employing highly magnetic rare-earth composite polymer

International Nuclear Information System (INIS)

Rahbar, Mona; Gray, Bonnie L; Shannon, Lesley

2016-01-01

We present a new magnetically actuated microfluidic valve that employs a highly magnetic composite polymer (M-CP) containing rare-earth hard-magnetic powder for its actuating element and for its valve seat. The M-CP offers much higher magnetization compared to the soft-magnetic, ferrite-based composite polymers typically used in microfluidic applications. Each valve consists of a permanently magnetized M-CP flap and valve seat mounted on a microfluidic channel system fabricated in poly(dimethylsiloxane) (PDMS). Each valve is actuated under a relatively small external magnetic field of 80 mT provided by a small permanent magnet mounted on a miniature linear actuator. The performance of the valve with different flap thicknesses is characterized. In addition, the effect of the magnetic valve seat on the valve’s performance is also characterized. It is experimentally shown that a valve with a 2.3 mm flap thickness, actuated under an 80 mT magnetic field, is capable of completely blocking liquid flow at a flow rate of 1 ml min −1 for pressures up to 9.65 kPa in microfluidic channels 200 μ m wide and 200 μ m deep. The valve can also be fabricated into an array for flow switching between multiple microfluidic channels under continuous flow conditions. The performance of arrays of valves for flow routing is demonstrated for flow rates up to 5 ml min −1 with larger microfluidic channels of up to 1 mm wide and 500 μ m deep. The design of the valves is compatible with other commonly used polymeric microfluidic components, as well as other components that use the same novel permanently magnetic composite polymer, such as our previously reported cilia-based mixing devices. (paper)

Novel passive normally closed microfluidic valve

CSIR Research Space (South Africa)

Land, K

2009-09-01

Full Text Available ’ represents the distance by which the membrane is depressed before actuation. This stretches the membrane to give it a pre-tension. Thus, when the pressure is removed from the inlet, the membrane returns to its original position, thereby closing the valve.... This also determines the pressure, pcritical, required to depress the membrane for actuation. Actuation occurs once the pressure from the input fluid reaches pcritical, the membrane is depressed and fluid flows freely from the inlet to the outlet. A...

Flow restrictor silicon membrane microvalve actuated by optically controlled paraffin phase transition

International Nuclear Information System (INIS)

Kolari, K; Havia, T; Stuns, I; Hjort, K

2014-01-01

Restrictor valves allow proportional control of fluid flow but are rarely integrated in microfluidic systems. In this study, an optically actuated silicon membrane restrictor microvalve is demonstrated. Its actuation is based on the phase transition of paraffin, using a paraffin wax mixed with a suitable concentration of optically absorbing nanographite particles. Backing up the membrane with oil (the melted paraffin) allows for a compliant yet strong contact to the valve seat, which enables handling of high pressures. At flow rates up to 30 µL min −1 and at a pressure of 2 bars, the valve can successfully be closed and control the flow level by restriction. The use of this paraffin composite as an adhesive layer sandwiched between the silicon valve and glass eases fabrication. This type of restrictor valve is best suited for high pressure, low volume flow silicon-based nanofluidic systems. (paper)

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

Science.gov (United States)

Wiles, Matthew A.; Marriot, Craig D

2013-07-02

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

Non-linear control of a hydraulic piezo-valve using a generalised Prandtl-Ishlinskii hysteresis model

Science.gov (United States)

Stefanski, Frederik; Minorowicz, Bartosz; Persson, Johan; Plummer, Andrew; Bowen, Chris

2017-01-01

The potential to actuate proportional flow control valves using piezoelectric ceramics or other smart materials has been investigated for a number of years. Although performance advantages compared to electromagnetic actuation have been demonstrated, a major obstacle has proven to be ferroelectric hysteresis, which is typically 20% for a piezoelectric actuator. In this paper, a detailed study of valve control methods incorporating hysteresis compensation is made for the first time. Experimental results are obtained from a novel spool valve actuated by a multi-layer piezoelectric ring bender. A generalised Prandtl-Ishlinskii model, fitted to experimental training data from the prototype valve, is used to model hysteresis empirically. This form of model is analytically invertible and is used to compensate for hysteresis in the prototype valve both open loop, and in several configurations of closed loop real time control system. The closed loop control configurations use PID (Proportional Integral Derivative) control with either the inverse hysteresis model in the forward path or in a command feedforward path. Performance is compared to both open and closed loop control without hysteresis compensation via step and frequency response results. Results show a significant improvement in accuracy and dynamic performance using hysteresis compensation in open loop, but where valve position feedback is available for closed loop control the improvements are smaller, and so conventional PID control may well be sufficient. It is concluded that the ability to combine state-of-the-art multi-layer piezoelectric bending actuators with either sophisticated hysteresis compensation or closed loop control provides a route for the creation of a new generation of high performance piezoelectric valves.

Space Shuttle Orbital Maneuvering Subsystem (OMS) Engine Propellant Leakage Ball-Valve Shaft Seals

Science.gov (United States)

Lueders, Kathy; Buntain, Nick; Fries, Joseph (Technical Monitor)

1999-01-01

Evidence of propellant leakage across ball-valve shaft seals has been noted during the disassembly of five flight engines and one test engine at the NASA Lyndon B. Johnson Space Center, White Sands Test Facility. Based on data collected during the disassembly of these five engines, the consequences of propellant leakage across the ball-valve shaft seals can be divided into four primary areas of concern: Damage to the ball-valve pinion shafts, damage to sleeved bearings inside the ball-valve and actuator assemblies, degradation of the synthetic rubber o-rings used in the actuator assemblies, and corrosion and degradation to the interior of the actuator assemblies. The exact time at which leakage across the ball-valve shaft seals occurs has not been determined, however, the leakage most likely occurs during engine firings when, depending on the specification used, ball-valve cavity pressures range as high as 453 to 550 psia. This potential pressure range for the ball-valve cavities greatly exceeds the acceptance leakage test pressure of 332 psia. Since redesign and replacement of the ball-valve shaft seals is unlikely, the near term solution to prevent damage that occurs from shaft-seal leakage is to implement a routine overhaul and maintenance program for engines in the fleet. Recommended repair, verification, and possible preventative maintenance measures are discussed in the paper.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Enhancement of pressurizer safety valve operability by seating design improvement

International Nuclear Information System (INIS)

Moisidis, N.T.; Ratiu, M.D.

1994-01-01

Operating conditions specific to Pressurizer Safety Valves (PSVs) have led to numerous problems and have caused industry and NRC concerns regarding the adequacy of spring loaded self-actuated safety valves for Reactor Coolant System (RCS) overpressure protection. Specific concerns are: setpoint drift, spurious actuations and leakage. Based on testing and valve construction analysis of a Crosby model 6M6 PSV, it was established that the primary contributor to the valve problems is a susceptibility to weak seating. To eliminate spring instability, a new spring washer was designed, which guides the spring and precludes its rotation from the reference installed position. Results of tests performed on a prototype PSV equipped with the modified upper spring washer has shown significant improvements in valve operability and a consistent setpoint reproducibility to less than ±1% of the PSV setpoint (testing of baseline, unmodified valve, resulted in a setpoint drift of ±2%). Enhanced valve operability will result in a significant decrease in operating and maintenance costs associated with valve maintenance and testing. In addition, the enhanced setpoint reproducibility will allow the development of a nitrogen to steam correlation for future in-house PSV testing which will result in further reductions in costs associated with valve testing

Optimization of a pressure control valve for high power automatic transmission considering stability

Science.gov (United States)

Jian, Hongchao; Wei, Wei; Li, Hongcai; Yan, Qingdong

2018-02-01

The pilot-operated electrohydraulic clutch-actuator system is widely utilized by high power automatic transmission because of the demand of large flowrate and the excellent pressure regulating capability. However, a self-excited vibration induced by the inherent non-linear characteristics of valve spool motion coupled with the fluid dynamics can be generated during the working state of hydraulic systems due to inappropriate system parameters, which causes sustaining instability in the system and leads to unexpected performance deterioration and hardware damage. To ensure a stable and fast response performance of the clutch actuator system, an optimal design method for the pressure control valve considering stability is proposed in this paper. A non-linear dynamic model of the clutch actuator system is established based on the motion of the valve spool and coupling fluid dynamics in the system. The stability boundary in the parameter space is obtained by numerical stability analysis. Sensitivity of the stability boundary and output pressure response time corresponding to the valve parameters are identified using design of experiment (DOE) approach. The pressure control valve is optimized using particle swarm optimization (PSO) algorithm with the stability boundary as constraint. The simulation and experimental results reveal that the optimization method proposed in this paper helps in improving the response characteristics while ensuring the stability of the clutch actuator system during the entire gear shift process.

Conceptual design of a compact absolute valve for the ITER neutral beam injectors

Energy Technology Data Exchange (ETDEWEB)

Jones, Chris [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)], E-mail: chris.m.jones@jet.uk; Waldon, Chris; Martin, David; Watson, Mike [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Sonderegger, Kurt; Lenherr, Bruno [VAT Vakuumventile AG, CH-9469 Haag (Switzerland); Andrews, Ian; Mansbridge, Simon [VAT Vacuum Products Ltd., Edmund House, Rugby Road, Leamington Spa, Warwickshire CV32 6EL (United Kingdom)

2009-06-15

The reference design for the ITER neutral beam injectors incorporated a fast shutter to limit tritium migration to the injector vacuum enclosures. In 2005, a need for an 'absolute' isolation valve was identified to facilitate injector maintenance procedures and protect the system from an in-vessel ingress of coolant event (ICE). An outline concept for an all-metal seal valve was developed during 2006, in close cooperation with the Swiss valve manufacturer VAT. During the following year, it became apparent that the length of beamline available for the valve was significantly less than originally envisaged, resulting in a radical revision of the design concept. A casing length of 760 mm has been achieved by means of major changes to the casing structure, plate dimensions, pendulum mechanism and seal actuators. A concept for a seal protection system has been developed to prevent beam line contamination reaching the valve components and to protect the valve plate from surface heating by plasma radiation. The new design concept has been extensively validated by analysis, including a whole-system FE model of the valve.

Design of the Modular Pneumatic Valve Terminal

Directory of Open Access Journals (Sweden)

Jakub E. TAKOSOGLU

2015-11-01

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

Investigations on Actuator Dynamics through Theoretical and Finite Element Approach

Directory of Open Access Journals (Sweden)

Somashekhar S. Hiremath

2010-01-01

Full Text Available This paper gives a new approach for modeling the fluid-structure interaction of servovalve component-actuator. The analyzed valve is a precision flow control valve-jet pipe electrohydraulic servovalve. The positioning of an actuator depends upon the flow rate from control ports, in turn depends on the spool position. Theoretical investigation is made for No-load condition and Load condition for an actuator. These are used in finite element modeling of an actuator. The fluid-structure-interaction (FSI is established between the piston and the fluid cavities at the piston end. The fluid cavities were modeled with special purpose hydrostatic fluid elements while the piston is modeled with brick elements. The finite element method is used to simulate the variation of cavity pressure, cavity volume, mass flow rate, and the actuator velocity. The finite element analysis is extended to study the system's linearized response to harmonic excitation using direct solution steady-state dynamics. It was observed from the analysis that the natural frequency of the actuator depends upon the position of the piston in the cylinder. This is a close match with theoretical and simulation results. The effect of bulk modulus is also presented in the paper.

Valve Concepts for Microfluidic Cell Handling

Directory of Open Access Journals (Sweden)

M. Grabowski

2010-01-01

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

Advantages of butterfly valves for power plants

International Nuclear Information System (INIS)

Lapadat, J.T.

1977-01-01

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

Fully Soft 3D-Printed Electroactive Fluidic Valve for Soft Hydraulic Robots.

Science.gov (United States)

Zatopa, Alex; Walker, Steph; Menguc, Yigit

2018-06-01

Soft robots are designed to utilize their compliance and contortionistic abilities to both interact safely with their environment and move through it in ways a rigid robot cannot. To more completely achieve this, the robot should be made of as many soft components as possible. Here we present a completely soft hydraulic control valve consisting of a 3D-printed photopolymer body with electrorheological (ER) fluid as a working fluid and gallium-indium-tin liquid metal alloy as electrodes. This soft 3D-printed ER valve weighs less than 10 g and allows for onboard actuation control, furthering the goal of an entirely soft controllable robot. The soft ER valve pressure-holding capabilities were tested under unstrained conditions, cyclic valve activation, and the strained conditions of bending, twisting, stretching, and indentation. It was found that the max holding pressure of the valve when 5 kV was applied across the electrodes was 264 kPa, and that the holding pressure deviated less than 15% from the unstrained max holding pressure under all strain conditions except for indentation, which had a 60% max pressure increase. In addition, a soft octopus-like robot was designed, 3D printed, and assembled, and a soft ER valve was used to stop the fluid flow, build pressure in the robot, and actuate six tentacle-like soft bending actuators.

A study on the force balance of an unbalanced globe valve

International Nuclear Information System (INIS)

Yang, Sang Min; Cho, Taik Dong; Ko, Sung Ho; Lee, Ho Young

2007-01-01

A pneumatic control valve is a piping element that controls the volumetric flow rate and pressure of a fluid: it is necessary to analyze the characteristics of the forces with respect to the opening of the valve in order to evaluate its operating performance. The forces occurring during operation are: resisting force and actuator force, where the load resistance is mostly affected by the fluid pressure difference of the valve. In this study, a force balance equation derived from the equilibrium relationship between the resisting force and the actuator force of an unbalanced globe valve is proposed, and the force balance equations are used to model the dynamic equations of a pneumatic unbalanced globe valve installed in nuclear power plants. A CFD analysis is also carried out to evaluate the pressure distribution and forces acting on the top and bottom planes of the valve plug. The results of this analysis have been verified through experimentation. This study has shown that the fluid pressure difference between the inlet and outlet of the valve, measured from the force balance equation of an unbalanced valve, should actually be examined with the fluid-pressure difference between the top and bottom side of the valve plug

3D Printed Multimaterial Microfluidic Valve.

Directory of Open Access Journals (Sweden)

Steven J Keating

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

Piezoelectric valve

Science.gov (United States)

Petrenko, Serhiy Fedorovich

2013-01-15

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

Design and experimental study of a novel giant magnetostrictive actuator

Energy Technology Data Exchange (ETDEWEB)

Xue, Guangming, E-mail: yy0youxia@163.com [Vehicle and Electrical Engineering Department, Ordnance Engineering College, Shijiazhuang, 050003 China (China); Zhang, Peilin; He, Zhongbo; Li, Dongwei; Huang, Yingjie [Vehicle and Electrical Engineering Department, Ordnance Engineering College, Shijiazhuang, 050003 China (China); Xie, Wenqiang [Cadre Rotational Training Brigade, Ordnance Engineering College, Shijiazhuang, 050003 China (China)

2016-12-15

Giant magnetostrictive actuator has been widely used in precise driving occasions for its excellent performance. However, in driving a switching valve, especially the ball-valve in an electronic controlled injector, the actuator can’t exhibit its good performance for limits in output displacement and responding speed. A novel giant magnetostrictive actuator, which can reach its maximum displacement for being exerted with no bias magnetic field, is designed in this paper. Simultaneously, elongating of the giant magetostrictive material is converted to shortening of the actuator's axial dimension with the help of an output rod in “T” type. Furthermore, to save responding time, the driving voltage with high opening voltage while low holding voltage is designed. Responding time and output displacement are studied experimentally with the help of a measuring system. From measured results, designed driving voltage can improve the responding speed of actuator displacement quite effectively. And, giant magnetostrictive actuator can output various steady-state displacements to reach more driving effects. - Highlights: • GMA with zero bias magnetic field can reach maximum displacement in one direction. • Driving wave with high opening voltage can promote GMA's responding speed. • Higher opening voltage is exerted, less rise time is reached. • Continuous displacements from 0 to maximum value can be achieved by GMA.

Control of soft machines using actuators operated by a Braille display.

Science.gov (United States)

Mosadegh, Bobak; Mazzeo, Aaron D; Shepherd, Robert F; Morin, Stephen A; Gupta, Unmukt; Sani, Idin Zhalehdoust; Lai, David; Takayama, Shuichi; Whitesides, George M

2014-01-07

One strategy for actuating soft machines (e.g., tentacles, grippers, and simple walkers) uses pneumatic inflation of networks of small channels in an elastomeric material. Although the management of a few pneumatic inputs and valves to control pressurized gas is straightforward, the fabrication and operation of manifolds containing many (>50) independent valves is an unsolved problem. Complex pneumatic manifolds-often built for a single purpose-are not easily reconfigured to accommodate the specific inputs (i.e., multiplexing of many fluids, ranges of pressures, and changes in flow rates) required by pneumatic systems. This paper describes a pneumatic manifold comprising a computer-controlled Braille display and a micropneumatic device. The Braille display provides a compact array of 64 piezoelectric actuators that actively close and open elastomeric valves of a micropneumatic device to route pressurized gas within the manifold. The positioning and geometries of the valves and channels in the micropneumatic device dictate the functionality of the pneumatic manifold, and the use of multi-layer soft lithography permits the fabrication of networks in a wide range of configurations with many possible functions. Simply exchanging micropneumatic devices of different designs enables rapid reconfiguration of the pneumatic manifold. As a proof of principle, a pneumatic manifold controlled a soft machine containing 32 independent actuators to move a ball above a flat surface.

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

Science.gov (United States)

2010-10-01

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

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

International Nuclear Information System (INIS)

Lowry, D.A.

1990-01-01

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

Hydraulic actuator for an electric circuit breaker

Science.gov (United States)

Imam, Imdad [Colonie, NY

1983-01-01

This actuator comprises a fluid motor having a piston, a breaker-opening space at one side of the piston, and a breaker-closing space at its opposite side. An accumulator freely communicates with the breaker-opening space for supplying pressurized fluid thereto during a circuit breaker opening operation. The breaker-opening space and the breaker-closing space are connected by an impeded flow passage. A pilot valve opens to allow the pressurized liquid in the breaker-closing space to flow to a back chamber of a normally closed main valve to cause the main valve to be opened during a circuit breaker opening operation to release the pressurized liquid from the breaker-closing space. An impeded passage affords communication between the back chamber and a sump located on the opposite side of the main valve from the back chamber. The pilot valve and impeded passage allow rapid opening of the main valve with pressurized liquid from the breaker closing side of the piston.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-05-15

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

Relief valve testing study

International Nuclear Information System (INIS)

BROMM, R.D.

2001-01-01

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

Can postoperative mean transprosthetic pressure gradient predict survival after aortic valve replacement?

NARCIS (Netherlands)

Koene, Bart M.; Hamad, Mohamed A. Soliman; Bouma, Wobbe; Mariani, Massimo A.; Peels, Kathinka C.; van Dantzig, Jan-Melle; van Straten, Albert H.

In this study, we sought to determine the effect of the mean transprosthetic pressure gradient (TPG), measured at 6 weeks after aortic valve replacement (AVR) or AVR with coronary artery bypass grafting (CABG) on late all-cause mortality. Between January 1998 and March 2012, 2,276 patients (mean age

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

DEFF Research Database (Denmark)

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

2015-01-01

A prototype of a fast switching valve for a digital hydraulic machine has been designed and manufactured. The valve is composed of an annular seat plunger connected with a moving coil actuator as the force producing element. The valve prototype is designed for flow rates of 600 l/min with less th...

NRC Information Notice No. 92-67: Deficiency in design modifications to address failures of Hiller actuators upon a gradual loss of air pressure

International Nuclear Information System (INIS)

Rossi, C.E.

1993-01-01

On January 7, 1992, Carolina Power and Light Company (Shearon Harris Plant) components associated with the air supply to the actuators of the three main feedwater preheater bypass isolation valves were not qualified for a Q class application. Specifically, the failure of the air pump in the non-Q Class, non-seismic instrument air supply to the valve actuator accumulator could prevent pressure switches upstream of the air pump from detecting slow leakage in the Q Class, seismic portion of the actuator air lines. The pressure switches were installed to ensure valve closure by sending an automatic close signal if the instrument air system pressure (upstream of the actuator air pump) dropped to 66 psig as discussed in IN 82-25. The main feedwater preheater bypass isolation valves function as containment isolation valves upon receipt of a feedwater isolation signal. The function of the air pump is to raise the normal instrument air supply pressure from 70 to 100 psig to approximately 150 psig. If accumulator pressure drops from 150 psig to 122 psig, the main feedwater preheater bypass isolation valve may not close within 10 seconds. If pressure drops to a value as low as 20 psig, it may not be sufficient to close the main feedwater preheater bypass isolation valve and keep it closed against the maximum differential pressure across the valve seat. Upon discovery of this condition, Shearon Harris established a surveillance interval for verifying that the actuators' components were functioning properly and that the accumulators were fully pressurized. On January 12, 1992, non-Q components were replaced with suitable components and testing was completed satisfactorily

Osmotic actuation for microfluidic components in point-of-care applications

KAUST Repository

Chen, Yu-Chih

2013-01-01

We present a novel design of micropumps and valves driven by osmotic force for point-of-care applications. Although there have been significant progresses in microfluidic components and control devices such as fluidic diodes, switches, resonators and digital-to-analog converters, the ultimate power source still depends on bulky off-chip components, which are expensive and cannot be easily miniaturized. For point-of-care applications, it is critical to integrate all the components in a compact size at low cost. In this work, we report two key active components actuated by osmotic mechanism for total integrated microfluidic system. For the proof of concept, we have demonstrated valve actuation, which can maintain stable ON/OFF switching operations under 125 kPa back pressure. We have also implemented an osmotic pump, which can pump a high flow rate over 30 μL/min for longer than 30 minutes. The experimental data demonstrates the possibility and potential of applying osmotic actuation in point-of-care disposable microfluidics. © 2013 IEEE.

Characteristics of electrostatic gas micro-pump with integrated polyimide passive valves

International Nuclear Information System (INIS)

Han, Jeahyeong; Yeom, Junghoon; Mensing, Glennys; Flachsbart, Bruce; Shannon, Mark A

2012-01-01

We report on the fabrication and characterization of electrostatic gas micro-pumps integrated with polyimide check valves. Touch-mode capacitance actuation, enabled by a fixed silicon electrode and a metal/polyimide diaphragm, creates the suction and push-out of the ambient gas; the gas flow is rectified by the check valves located at the inlet and outlet of the pump. The fabricated pumps were tested with various actuation voltages at different frequencies and duty cycles; an emphasis was placed on investigating the effect of valve flow conductance on the gas pumping characteristics. The pump with higher valve conductance could increase the operating frequency of the pump and affect the pumping characteristics from a pulsating flow to a continuous flow, leading to a higher gas flow rate. This electrostatic pump has a flow control resolution of 1 µL min −1 ; it could generate a gas flow up to 106 µL min −1 . (paper)

Design of a Soft Robot with Multiple Motion Patterns Using Soft Pneumatic Actuators

Science.gov (United States)

Miao, Yu; Dong, Wei; Du, Zhijiang

2017-11-01

Soft robots are made of soft materials and have good flexibility and infinite degrees of freedom in theory. These properties enable soft robots to work in narrow space and adapt to external environment. In this paper, a 2-DOF soft pneumatic actuator is introduced, with two chambers symmetrically distributed on both sides and a jamming cylinder along the axis. Fibers are used to constrain the expansion of the soft actuator. Experiments are carried out to test the performance of the soft actuator, including bending and elongation characteristics. A soft robot is designed and fabricated by connecting four soft pneumatic actuators to a 3D-printed board. The soft robotic system is then established. The pneumatic circuit is built by pumps and solenoid valves. The control system is based on the control board Arduino Mega 2560. Relay modules are used to control valves and pressure sensors are used to measure pressure in the pneumatic circuit. Experiments are conducted to test the performance of the proposed soft robot.

Air Muscle Actuated Low Cost Humanoid Hand

Directory of Open Access Journals (Sweden)

Peter Scarfe

2008-11-01

Full Text Available The control of humanoid robot hands has historically been expensive due to the cost of precision actuators. This paper presents the design and implementation of a low-cost air muscle actuated humanoid hand developed at Curtin University of Technology. This hand offers 10 individually controllable degrees of freedom ranging from the elbow to the fingers, with overall control handled through a computer GUI. The hand is actuated through 20 McKibben-style air muscles, each supplied by a pneumatic pressure-balancing valve that allows for proportional control to be achieved with simple and inexpensive components. The hand was successfully able to perform a number of human-equivalent tasks, such as grasping and relocating objects.

Air Muscle Actuated Low Cost Humanoid Hand

Directory of Open Access Journals (Sweden)

Peter Scarfe

2006-06-01

Full Text Available The control of humanoid robot hands has historically been expensive due to the cost of precision actuators. This paper presents the design and implementation of a low-cost air muscle actuated humanoid hand developed at Curtin University of Technology. This hand offers 10 individually controllable degrees of freedom ranging from the elbow to the fingers, with overall control handled through a computer GUI. The hand is actuated through 20 McKibben-style air muscles, each supplied by a pneumatic pressure-balancing valve that allows for proportional control to be achieved with simple and inexpensive components. The hand was successfully able to perform a number of human-equivalent tasks, such as grasping and relocating objects.

Experience with control valve cavitation problems and their solutions

International Nuclear Information System (INIS)

Ozol, J.

1988-01-01

Pressure reduction in control valves can induce cavitation, which has three effects on the control valve. Firstly, it modifies or changes the hydraulic performance of the control valve. Since control valves are designed for noncavitating conditions, the result is usually reduced stability of the control valve or, in extreme cavitating conditions known as supercavitation, the valve may limit the flow rate and thus be undersized. Secondly, cavitation can cause material damage to valve parts, trim, or valve body, or erodes downstream piping; consequently, the valve or piping leaks. Thirdly, cavitation causes noise and vibration, which may cause major damage or destruction to equipment such as valve positioners, actuators, pipe supports and sometimes to other downstream valves. The purpose of this paper is twofold: (1) It describes the I.S.A. valve sizing equations and how they relate to cavitation. (2) It describes experiences with these three problems, and discusses corrective actions and practical approaches to their solution. This paper discusses thirteen cavitation experiences

Part-turn gearboxes for electric actuators; Schwenkgetriebe fuer elektrische Stellantriebe

Energy Technology Data Exchange (ETDEWEB)

Herbstritt, M. [Riester (W.) GmbH und Co. KG, Muellheim (Germany)

2002-09-01

Different types of gearboxes provide a useful complement to the electric actuator type ranges. The gearboxes can be combined with the actuators in many ways. Multi-turn actuators, for example, can be turned into part-turn actuators. When using a modular system, a suitable solution for almost any automation task in the field of industrial valves can be found. (orig.) [German] Sinnvoll ergaenzt werden elektrische Stellantriebe fuer Armaturen durch verschiedene Arten von Getrieben. Die Getriebe sind in vielfaeltiger Weise mit den Stellantrieben kombinierbar. So werden beispielsweise aus Drehantrieben Schwenkantriebe. Mit einem Baukasten-System laesst sich so fuer nahezu jede Automatisierungsaufgabe im Bereich der Industriearmaturen eine passende Loesung finden. (orig.)

Steam relief valve control system for a nuclear reactor

International Nuclear Information System (INIS)

Torres, J.M.

1976-01-01

Described is a turbine follow system and method for Pressurized Water Reactors utilizing load bypass and/or atmospheric dump valves to provide a substitute load upon load rejection by bypassing excess steam to a condenser and/or to the atmosphere. The system generates a variable pressure setpoint as a function of load and applies an error signal to modulate the load bypass valves. The same signal which operates the bypass valves actuates a control rod automatic withdrawal prevent to insure against reactor overpower

The use of valves in the SAGD process

Energy Technology Data Exchange (ETDEWEB)

Romano, Michael A. [Global Marketing, Oil and Gas, Tyco Valves and Controls (United States)

2011-07-01

Steam-assisted gravity drainage (SAGD) is a developing technology, the aim of which is to increase production of bitumen while minimizing its environmental footprint. Valves must meet the process conditions of the operations, which depend on weel depth: deeper reservoirs of bitumen require higher steam injection pressure. A wide range of valves is used throughout the SAGD process. In the water softening plant, butterfly and process lined valves are used. HP gate valves are used for isolation, globe valves for vents/drains/bypasses, along with ARC valves for steam and booster pump projection with steam traps on injection lines in steam injection. Isolation valves are used throughout the low pressure process including ball, gate and triple-offset valves. Pressure management is carried out on all pressure vessels and lines. Control and choke valves are installed on well pads and production. Instrumentation, actuation and controls are installed throughout. In the ideal situation, suppliers and process engineers would work together in the early stages of a project.

Performance evaluation of a piezoactuator-based single-stage valve system subjected to high temperature

Science.gov (United States)

Jeon, Juncheol; Han, Chulhee; Chung, Jye Ung; Choi, Seung-Bok

2015-01-01

In this paper, a novel single-stage valve system activated by a piezostack actuator is proposed and experimentally evaluated at both room temperature (20 °C) and high temperature (100 °C) conditions. A hinge-lever displacement amplifier is adopted in the valve system to magnify the displacement generated from the piezostack actuator. After explaining the operating principle of the proposed piezostack-driven single-stage valve system, the geometric dimensions and mechanical properties of the valve components are discussed in details. An experimental apparatus is then manufactured to evaluate the performances of the valve system such as flow rate. The experimental apparatus consists of a heat chamber, which can regulate the temperature of the valve system and oil, pneumatic-hydraulic cylinders, a hydraulic circuit, a pneumatic circuit, electronic devices, an interface card, and a high voltage amplifier. The pneumatic-hydraulic cylinder transforms the pneumatic pressure into hydraulic pressure. The performances of the valve system regarding spool response, pressure drop, and flow rate are evaluated and presented. In addition, the performance of the valve system under high temperature condition is compared with that under room temperature condition. The experimental results are plotted in both frequency and time domains.

Performance evaluation of a piezoactuator-based single-stage valve system subjected to high temperature

International Nuclear Information System (INIS)

Jeon, Juncheol; Han, Chulhee; Ung Chung, Jye; Choi, Seung-Bok

2015-01-01

In this paper, a novel single-stage valve system activated by a piezostack actuator is proposed and experimentally evaluated at both room temperature (20 °C) and high temperature (100 °C) conditions. A hinge-lever displacement amplifier is adopted in the valve system to magnify the displacement generated from the piezostack actuator. After explaining the operating principle of the proposed piezostack-driven single-stage valve system, the geometric dimensions and mechanical properties of the valve components are discussed in details. An experimental apparatus is then manufactured to evaluate the performances of the valve system such as flow rate. The experimental apparatus consists of a heat chamber, which can regulate the temperature of the valve system and oil, pneumatic-hydraulic cylinders, a hydraulic circuit, a pneumatic circuit, electronic devices, an interface card, and a high voltage amplifier. The pneumatic-hydraulic cylinder transforms the pneumatic pressure into hydraulic pressure. The performances of the valve system regarding spool response, pressure drop, and flow rate are evaluated and presented. In addition, the performance of the valve system under high temperature condition is compared with that under room temperature condition. The experimental results are plotted in both frequency and time domains. (paper)

Control of an air pressure actuated disposable bioreactor for cultivating heart valves

NARCIS (Netherlands)

Beelen, M.J.; Neerincx, P.E.; Molengraft, van de M.J.G.

2011-01-01

A disposable injection molded bioreactor for growing tissue-engineered heart valves is controlled to mimic the physiological heart cycle. Tissue-engineered heart valves, cultured from human stem cells, are a possible alternative for replacing failing aortic heart valves, where nowadays biological

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

Science.gov (United States)

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

2015-01-01

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

Math Machines: Using Actuators in Physics Classes

Science.gov (United States)

Thomas, Frederick J.; Chaney, Robert A.; Gruesbeck, Marta

2018-01-01

Probeware (sensors combined with data-analysis software) is a well-established part of physics education. In engineering and technology, sensors are frequently paired with actuators--motors, heaters, buzzers, valves, color displays, medical dosing systems, and other devices that are activated by electrical signals to produce intentional physical…

Diagnostic for two-mode variable valve activation device

Science.gov (United States)

Fedewa, Andrew M

2014-01-07

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

Development of a hybrid safety system: Actuation of the secondary automatic depressurization system at an early stage

International Nuclear Information System (INIS)

Nishimoto, Masae; Umezawa, Shigemitsu; Okabe, Kazuharu; Matsuoka, Tsuyoshi

1996-01-01

A Hybrid Safety System, which is an optimum combination of active and passive safety systems, has been developed in order to improve the safety, reliability and economic features of the next generation of PWRs. The passive safety systems include Automatic primary Depressurization System (ADS), Secondary Automatic Depressurization System (SADS), advanced accumulators, gravity injection system and so on. In this study the authors have improved the actuation logic of the passive safety systems. The original logic in the previous study actuates ADS at an early stage of an event such as a Loss-of-Coolant Accident (LOCA), and this is followed by the actuation of SADS. In this study they divide SADS into two systems. The first, small SADS, uses small valves corresponding to the relief valves of the conventional PWR plants. The second, large SADS, corresponds to the original SADS using multiple valves of large capacity. With the new logic, the passive systems are actuated during a typical small LOCA. Small LOCA analyses using several break areas were performed for a 1,400 MWe PWR plant with a Hybrid Safety System. The results predict that core uncovery does not occur in the case of a relatively small break area and that core heat removal during a small LOCA is improved in comparison with the analyses for conventional PWR plants, where the secondary pressure remains higher during the event. The results also predict that this new logic make it possible to reduce the ADS valve size and the actuation pressure setpoint of the passive safety systems

Compressed gas domestic aerosol valve design using high viscous product

Directory of Open Access Journals (Sweden)

A Nourian

2016-10-01

Full Text Available Most of the current universal consumer aerosol products using high viscous product such as cooking oil, antiperspirants, hair removal cream are primarily used LPG (Liquefied Petroleum Gas propellant which is unfriendly environmental. The advantages of the new innovative technology described in this paper are: i. No butane or other liquefied hydrocarbon gas is used as a propellant and it replaced with Compressed air, nitrogen or other safe gas propellant. ii. Customer acceptable spray quality and consistency during can lifetime iii. Conventional cans and filling technology There is only a feasible energy source which is inert gas (i.e. compressed air to replace VOCs (Volatile Organic Compounds and greenhouse gases, which must be avoided, to improve atomisation by generating gas bubbles and turbulence inside the atomiser insert and the actuator. This research concentrates on using "bubbly flow" in the valve stem, with injection of compressed gas into the passing flow, thus also generating turbulence. The new valve designed in this investigation using inert gases has advantageous over conventional valve with butane propellant using high viscous product (> 400 Cp because, when the valving arrangement is fully open, there are negligible energy losses as fluid passes through the valve from the interior of the container to the actuator insert. The use of valving arrangement thus permits all pressure drops to be controlled, resulting in improved control of atomising efficiency and flow rate, whereas in conventional valves a significant pressure drops occurs through the valve which has a complex effect on the corresponding spray.

Hydraulic System Design of Hydraulic Actuators for Large Butterfly Valves

Directory of Open Access Journals (Sweden)

Ye HUANG

2014-09-01

Full Text Available Hydraulic control systems of butterfly valves are presently valve-controlled and pump-controlled. Valve-controlled hydraulic systems have serious power loss and generate much heat during throttling. Pump-controlled hydraulic systems have no overflow or throttling losses but are limited in the speed adjustment of the variable-displacement pump, generate much noise, pollute the environment, and have motor power that does not match load requirements, resulting in low efficiency under light loads and wearing of the variable-displacement pump. To overcome these shortcomings, this article designs a closed hydraulic control system in which an AC servo motor drives a quantitative pump that controls a spiral swinging hydraulic cylinder, and analyzes and calculates the structure and parameters of a spiral swinging hydraulic cylinder. The hydraulic system adjusts the servo motor’s speed according to the requirements of the control system, and the motor power matches the power provided to components, thus eliminating the throttling loss of hydraulic circuits. The system is compact, produces a large output force, provides stable transmission, has a quick response, and is suitable as a hydraulic control system of a large butterfly valve.

Active combustion flow modulation valve

Science.gov (United States)

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

2013-09-24

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

High Temperature, High Frequency Fuel Metering Valve, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Active Signal Technologies and its subcontractor Moog propose to develop a high-frequency actuator driven valve intended to achieve TRL 6 by the end of Phase II....

Design Optimization of Moving Magnet Actuated Valves for Digital Displacement Machines

DEFF Research Database (Denmark)

Madsen, Esben Lundø; Jørgensen, Janus Martin Thastum; Nørgård, Christian

2017-01-01

High-efficiency hydraulic machines using digital valves are presently a topic of great focus. Digital valve performance with respect to pressure loss, closing time as well as electrical power consumption, is key to obtaining high efficiency. A recent digital seat valve design developed at Aalborg...... optimized design closes in 2.1 ms, has a pressure drop of 0.8 bar at 150 l/min and yields a digital displacement machine average chamber efficiency of 98.9%. The design is simple in construction and uses a single coil, positioned outside the pressure chamber, eliminating the need for an electrical interface...

Nuclear reactor steam depressurization valve

International Nuclear Information System (INIS)

Moore, G.L.

1991-01-01

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

Design method for marine direct drive volume control ahead actuator

Directory of Open Access Journals (Sweden)

WANG Haiyang

2018-02-01

Full Text Available [Objectives] In order to reduce the size, weight and auxiliary system configuration of marine ahead actuators, this paper proposes a kind of direct drive volume control electro-hydraulic servo ahead actuator. [Methods] The protruding and indenting control of the servo oil cylinder are realized through the forward and reverse of the bidirectional working gear pump, and the flow matching valve implements the self-locking of the ahead actuator in the target position. The mathematical model of the ahead actuator is established, and an integral separation fuzzy PID controller designed. On this basis, using AMESim software to build a simulation model of the ahead actuator, and combined with testing, this paper completes an analysis of the control strategy research and dynamic and static performance of the ahead actuator. [Results] The experimental results agree well with the simulation results and verify the feasibility of the ahead actuator's design. [Conclusions] The research results of this paper can provide valuable references for the integration and miniaturization design of marine ahead actuators.

A piezoelectric micro control valve with integrated capacitive sensing for ambulant blood pressure waveform monitoring

NARCIS (Netherlands)

Groen, Maarten; Wu, Kai; Brookhuis, Robert Anton; van Houwelingen, Marc J.; Brouwer, Dannis Michel; Lötters, Joost Conrad; Wiegerink, Remco J.

2014-01-01

We have designed and characterized a MEMS microvalve with built-in capacitive displacement sensing and fitted it with a miniature piezoelectric actuator to achieve active valve control. The integrated displacement sensor enables high bandwidth proportional control of the gas flow through the valve.

Valving for controlling a fluid-driven reciprocating apparatus

Science.gov (United States)

Whitehead, John C.

1995-01-01

A pair of control valve assemblies for alternately actuating a pair of fluid-driven free-piston devices by using fluid pressure communication therebetween. Each control valve assembly is switched by a pressure signal depending on the state of its counterpart's piston. The communication logic is arranged to provide overlap of the forward strokes of the pistons, so that at least one of the pair will always be pressurized. Thus, uninterrupted pumping of liquid is made possible from a pair of free-piston pumps. In addition, the speed and frequency of piston stroking is entirely dependent on the mechanical power load applied. In the case of a pair of pumps, this enables liquid delivery at a substantially constant pressure over the full range of flow rates, from zero to maximum flow. Each of the valve assemblies uses an intake-exhaust valve and a signal valve with the signal valve of one pump being connected to be pressure responsive to the piston of the opposite cylinder or pump.

Fast force actuators for LSST primary/tertiary mirror

Science.gov (United States)

Hileman, Edward; Warner, Michael; Wiecha, Oliver

2010-07-01

The very short slew times and resulting high inertial loads imposed upon the Large Synoptic Survey Telescope (LSST) create new challenges to the primary mirror support actuators. Traditionally large borosilicate mirrors are supported by pneumatic systems, which is also the case for the LSST. These force based actuators bear the weight of the mirror and provide active figure correction, but do not define the mirror position. A set of six locating actuators (hardpoints) arranged in a hexapod fashion serve to locate the mirror. The stringent dynamic requirements demand that the force actuators must be able to counteract in real time for dynamic forces on the hardpoints during slewing to prevent excessive hardpoint loads. The support actuators must also maintain the prescribed forces accurately during tracking to maintain acceptable mirror figure. To meet these requirements, candidate pneumatic cylinders incorporating force feedback control and high speed servo valves are being tested using custom instrumentation with automatic data recording. Comparative charts are produced showing details of friction, hysteresis cycles, operating bandwidth, and temperature dependency. Extremely low power actuator controllers are being developed to avoid heat dissipation in critical portions of the mirror and also to allow for increased control capabilities at the actuator level, thus improving safety, performance, and the flexibility of the support system.

Motor operated valves problems tests and simulations

Energy Technology Data Exchange (ETDEWEB)

Pinier, D.; Haas, J.L.

1996-12-01

An analysis of the two refusals of operation of the EAS recirculation shutoff valves enabled two distinct problems to be identified on the motorized valves: the calculation methods for the operating torques of valves in use in the power plants are not conservative enough, which results in the misadjustement of the torque limiters installed on their motorizations, the second problem concerns the pressure locking phenomenon: a number of valves may entrap a pressure exceeding the in-line pressure between the disks, which may cause a jamming of the valve. EDF has made the following approach to settle the first problem: determination of the friction coefficients and the efficiency of the valve and its actuator through general and specific tests and models, definition of a new calculation method. In order to solve the second problem, EDF has made the following operations: identification of the valves whose technology enables the pressure to be entrapped: the tests and numerical simulations carried out in the Research and Development Division confirm the possibility of a {open_quotes}boiler{close_quotes} effect: determination of the necessary modifications: development and testing of anti-boiler effect systems.

Motor operated valves problems tests and simulations

International Nuclear Information System (INIS)

Pinier, D.; Haas, J.L.

1996-01-01

An analysis of the two refusals of operation of the EAS recirculation shutoff valves enabled two distinct problems to be identified on the motorized valves: the calculation methods for the operating torques of valves in use in the power plants are not conservative enough, which results in the misadjustement of the torque limiters installed on their motorizations, the second problem concerns the pressure locking phenomenon: a number of valves may entrap a pressure exceeding the in-line pressure between the disks, which may cause a jamming of the valve. EDF has made the following approach to settle the first problem: determination of the friction coefficients and the efficiency of the valve and its actuator through general and specific tests and models, definition of a new calculation method. In order to solve the second problem, EDF has made the following operations: identification of the valves whose technology enables the pressure to be entrapped: the tests and numerical simulations carried out in the Research and Development Division confirm the possibility of a open-quotes boilerclose quotes effect: determination of the necessary modifications: development and testing of anti-boiler effect systems

Recommendations for main line block valves installation in gas pipelines; Recomendacoes para instalacao de valvulas de bloqueio de linha tronco em gasodutos

Energy Technology Data Exchange (ETDEWEB)

Frisoli, Caetano [TRANSPETRO - PETROBRAS Transportes, Rio de Janeiro, RJ (Brazil); Oliveira, Valeriano Duque de [PETROBRAS, Rio de Janeiro, RJ (Brazil)

2003-07-01

Cases of gas pipelines block valves and its pneumatic actuators presenting problems during the final pipeline commissioning and pre-operation phases, like internal leaks, leaking to the atmosphere, pneumatic circuit defects caused by water and debris, are nearly common. The majority can be avoided if a series of measuring are to be planned and implemented, as well as if an adequate planning of commissioning operations and line gasification, valves and actuators, are to be applied. This paper shows the practical experience in the construction and commissioning of valves and its actuators in the Bolivia-Brazil gas pipeline, which, in the first construction phase had a series of problems. After the diagnosis a set of procedures was implemented in the secondary construction phase, resulting in insignificant problems detected. All measures and procedures taken in the planning process, as well as additional aspects related to the main line valve design, its by-passes and supports, are demonstrated. (author)

High-authority smart material integrated electric actuator

Science.gov (United States)

Weisensel, G. N.; Pierce, Thomas D.; Zunkel, Gary

1997-05-01

For many current applications, hydraulic power is still the preferred method of gaining mechanical advantage. However, in many of these applications, this power comes with the penalties of high weight, size, cost, and maintenance due to the system's distributed nature and redundancy requirements. A high authority smart material Integrated Electric Actuator (IEA) is a modular, self-contained linear motion device that is capable of producing dynamic output strokes similar to those of hydraulic actuators yet at significantly reduced weight and volume. It provides system simplification and miniaturization. This actuator concept has many innovative features, including a TERFENOL-D-based pump, TERFENOL-D- based active valves, control algorithms, a displacement amplification unit and integrated, unitized packaging. The IEA needs only electrical power and a control command signal as inputs to provide high authority, high response rate actuation. This approach is directly compatible with distributed control strategies. Aircraft control, automotive brakes and fuel injection, and fluid power delivery are just some examples of the IEA's pervasive applications in aerospace, defense and commercial systems.

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

Science.gov (United States)

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

2017-07-01

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

ToF-SIMS Characterization of Biocompatible Silk/Polypyrrole Electromechanical Actuators

Science.gov (United States)

Bradshaw, Nathan; Severt, Sean; Wang, Zhaoying; Klemke, Carly; Larson, Jesse; Zhu, Zihua; Murphy, Amanda; Leger, Janelle

2015-03-01

Materials capable of controlled movements that can also interface with biological environments are highly sought after for biomedical devices such as valves, blood vessel sutures, cochlear implants and controlled drug release devices. Recently we have reported the synthesis of films composed of a conductive interpenetrating network of the biopolymer silk fibroin and poly(pyrrole). These silk-PPy composites function as bilayer electromechanical actuators in a biologically-relevant environment, can be actuated repeatedly, and are able to generate forces comparable with natural muscle (>0.1 MPa), making them an ideal candidate for interfacing with biological tissues. Here, time of flight secondary ion mass spectrometry was used to investigate the migration of ions in the devices during actuation. These findings will be discussed in the context of the actuation mechanism and opportunities for further improvements in device stability and performance.

Timing tests: automatic valve closure for tritium leaks

International Nuclear Information System (INIS)

Hanel, S.

1976-01-01

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

Empirical modeling of dynamic behaviors of pneumatic artificial muscle actuators.

Science.gov (United States)

Wickramatunge, Kanchana Crishan; Leephakpreeda, Thananchai

2013-11-01

Pneumatic Artificial Muscle (PAM) actuators yield muscle-like mechanical actuation with high force to weight ratio, soft and flexible structure, and adaptable compliance for rehabilitation and prosthetic appliances to the disabled as well as humanoid robots or machines. The present study is to develop empirical models of the PAM actuators, that is, a PAM coupled with pneumatic control valves, in order to describe their dynamic behaviors for practical control design and usage. Empirical modeling is an efficient approach to computer-based modeling with observations of real behaviors. Different characteristics of dynamic behaviors of each PAM actuator are due not only to the structures of the PAM actuators themselves, but also to the variations of their material properties in manufacturing processes. To overcome the difficulties, the proposed empirical models are experimentally derived from real physical behaviors of the PAM actuators, which are being implemented. In case studies, the simulated results with good agreement to experimental results, show that the proposed methodology can be applied to describe the dynamic behaviors of the real PAM actuators. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Evaluation of existing EPRI and INEL test data to determine the worm to worm gear coefficient of friction in Limitorque actuators

Energy Technology Data Exchange (ETDEWEB)

Garza, I.A.

1996-12-01

About the last sizing parameter for motor operated valves which has not been determined by utility or NRC sponsored testing is actuator efficiency. A by-product of EPRI testing for valve factors is the measurement of the actuator efficiencies. Motor sizing in this testing provides efficiency testing for motors running near synchronous speed. INEL testing, sponsored by the NRC, for stem factors and rate of loading provides complimentary data for motors loaded down to zero speed. This paper analyzes the data from these two test programs to determine the coefficient of friction for the worm to worm gear interface. This allowed the development of an algorithm for determining the efficiency of actuators which have not been tested. This paper compares the results of this algorithm to the test data to provide a measure of the accuracy of this method for calculating actuator efficiency.

Evaluation of existing EPRI and INEL test data to determine the worm to worm gear coefficient of friction in Limitorque actuators

International Nuclear Information System (INIS)

Garza, I.A.

1996-01-01

About the last sizing parameter for motor operated valves which has not been determined by utility or NRC sponsored testing is actuator efficiency. A by-product of EPRI testing for valve factors is the measurement of the actuator efficiencies. Motor sizing in this testing provides efficiency testing for motors running near synchronous speed. INEL testing, sponsored by the NRC, for stem factors and rate of loading provides complimentary data for motors loaded down to zero speed. This paper analyzes the data from these two test programs to determine the coefficient of friction for the worm to worm gear interface. This allowed the development of an algorithm for determining the efficiency of actuators which have not been tested. This paper compares the results of this algorithm to the test data to provide a measure of the accuracy of this method for calculating actuator efficiency

A Solar Energy Powered Autonomous Wireless Actuator Node for Irrigation Systems

OpenAIRE

Lajara, Rafael; Alberola, Jorge; Pelegr?-Sebasti?, Jos?

2010-01-01

The design of a fully autonomous and wireless actuator node ("wEcoValve mote") based on the IEEE 802.15.4 standard is presented. The system allows remote control (open/close) of a 3-lead magnetic latch solenoid, commonly used in drip irrigation systems in applications such as agricultural areas, greenhouses, gardens, etc. The very low power consumption of the system in conjunction with the low power consumption of the valve, only when switching positions, allows the system to be solar powered...

Robust Control of a Hydraulically Actuated Manipulator Using Sliding Mode Control

DEFF Research Database (Denmark)

Hansen, Michael Rygaard; Andersen, Torben Ole; Pedersen, Henrik Clemmensen

2005-01-01

This paper presents an approach to robust control called sliding mode control (SMC) applied to the a hydraulic servo system (HSS), consisting of a servo valve controlled symmetrical cylinder. The motivation for applying sliding mode control to hydraulically actuated systems is its robustness...

Valve packing manual. A maintenance application guide

International Nuclear Information System (INIS)

Aikin, J.A.; McCutcheon, R.G.; Cumming, D.

1997-01-01

Since 1970, AECL Chalk River Mechanical Equipment Development (MED) branch has invested over 175 person years in testing related to improving valve packing performance. Successful developments, including, 'live-loading', reduced packing heights, and performance-based packing qualification testing have been implemented. Since 1986, MED and the Integrated Valve Actuator Program Task Force - Valve Packing Steering Committee (IVAP-VPSC) have been involved in the development of combination die-formed graphite packing for use in CANDU plants. Many reports, articles, and specifications have been issued. Due to the large amount of test data and reports, a more user-friendly document has been prepared for everyday use. The Valve Packing Manual is based on many years of MED research and testing, as well as operating experience from CANDU nuclear generating stations (NGS). Since 1986, packing research and testing has been funded by the CANDU Owners Group (COG), the Electric Power Research Institute (EPRI), and participating valve packing manufacturers. The Valve Packing Manual (VPM) provides topical summaries of all work related to valve packing done since 1985. It includes advances in configuration design, stem packing friction, materials specifications, and installation procedures. This paper provides an overview on the application of the VPM with a focus on qualification testing, packing configuration, and stem packing friction. (author)

Pressure Control of a Pneumatic Actuator Using On/O Solenoid Valves

OpenAIRE

Jeddi Tehrani, Maisam

2008-01-01

Nowadays a very important aspect in heavy duty vehicles is the braking system. The braking system can be divided into EBS brakes, exhaust brake and retarder, where the latter is of interest in the present Master's Thesis. This thesis presents an investigation whether it is possible to substitute today's concept, i.e. controlling the air pressure to the retarder using a proportional-valve, with two so-called on/o®-valves and a pressure sensor, which will reduce expenses and contingently hyster...

Motor operated valve testing and the 'rate of loading' phenomenon

International Nuclear Information System (INIS)

Black, B.R.

1991-01-01

This paper discusses valve design features which affect the ability to predict motor operated valve (MOV) performance and reviews factors which should be considered when selecting switch settings to limit stem loads. Considerable attention is given to the rate of loading phenomenon which affects the relationship between valve stem thrust and actuator spring pack deflection. Equations are developed, and testing is discussed which permit the construction of an MOV dynamic model. Factors which must be considered when maintaining switch settings correct throughout the life of the plant are discussed. And switch setting acceptance criteria for use with baseline Static and Design Basis testing are suggested

Application of Model Based Prognostics to Pneumatic Valves in a Cryogenic Propellant Loading Testbed

Data.gov (United States)

National Aeronautics and Space Administration — Pneumatic-actuated valves are critical components in many applications, including cryogenic propellant loading for space operations. For these components, failures...

Role of passive valves & devices in poison injection system of advanced heavy water reactor

International Nuclear Information System (INIS)

Sapra, M.K.; Kundu, S.; Vijayan, P.K.; Vaze, K.K.; Sinha, R.K.

2014-01-01

The Advanced Heavy Water Reactor (AHWR) is a 300 MWe pressure tube type boiling light water (H 2 O) cooled, heavy water (D 2 O) moderated reactor. The reactor design is based on well-proven water reactor technologies and incorporates a number of passive safety features such as natural circulation core cooling; direct in-bundle injection of light water coolant during a Loss of Coolant Accident (LOCA) from Advanced Accumulators and Gravity Driven Water Pool by passive means; Passive Decay Heat Removal using Isolation Condensers, Passive Containment Cooling System and Passive Containment Isolation System. In addition to above, there is another passive safety system named as Passive Poison Injection System (PPIS) which is capable of shutting down the reactor for a prolonged time. It is an additional safety system in AHWR to fulfill the shutdown function in the event of failure of wired shutdown systems i.e. primary and secondary shut down systems of the reactor. When demanded, PPIS injects the liquid poison into the moderator by passive means using passive valves and devices. On increase of main heat transport (MHT) system pressure beyond a predetermined value, a set of rupture disks burst, which in-turn actuate the passive valve. The opening of passive valve initiates inrush of high pressure helium gas into poison tanks to push the poison into the moderator system, thereby shutting down the reactor. This paper primarily deals with design and development of Passive Poison Injection System (PPIS) and its passive valves & devices. Recently, a prototype DN 65 size Poison Injection Passive Valve (PIPV) has been developed for AHWR usage and tested rigorously under simulated conditions. The paper will highlight the role of passive valves & devices in PPIS of AHWR. The design concept and test results of passive valves along with rupture disk performance will also be covered. (author)

Analysis of Dielectric Electro Active Polymer Actuator and its High Voltage Driving Circuits

DEFF Research Database (Denmark)

Thummala, Prasanth; Huang, Lina; Zhang, Zhe

2012-01-01

Actuators based on dielectric elastomers have promising applications in artificial muscles, space robotics, mechatronics, micro-air vehicles, pneumatic and electric automation technology, heating valves, loud speakers, tissue engineering, surgical tools, wind turbine flaps, toys, rotary motors...

Research design and improvement of high temperature high pressure solenoid valve

International Nuclear Information System (INIS)

Luo Yongtang

1987-12-01

A process for development of the pilot type high temperature high pressure solenoid valve used in a PWR power plant is described. The whole development process might be divided into two phases: research design and improvement. In the former phase the questions had chiefly been approached in the following several aspects: the principle construction design, the determination of values for the constructionally key elements, the valve seal design and the solenoid actuator design, and made such valve's successful design in the main. In the latter phase an improvement had been made upon such valve against the problems during the testing use of the valve for a period of time, i.e. the unsatisfactory leak tightness, and achieved satisfactory results. The consummate success in this development not only has met the needs of the engineering project, but also made us obtain a valuable experience useful to design the similar valves

Investigating the performance and properties of dielectric elastomer actuators as a potential means to actuate origami structures

International Nuclear Information System (INIS)

Ahmed, S; Ounaies, Z; Frecker, M

2014-01-01

Origami engineering aims to combine origami principles with advanced materials to yield active origami shapes, which fold and unfold in response to external stimuli. This paper explores the potential and limitations of dielectric elastomers (DEs) as the enabling material in active origami engineering. DEs are compliant materials in which the coupled electro-mechanical actuation takes advantage of their low modulus and high breakdown strength. Until recently, prestraining of relatively thick DE materials was necessary in order to achieve the high electric fields needed to trigger electrostatic actuation without inducing a dielectric breakdown. Although prestrain improves the breakdown strength of the DE films and reduces the voltage required for actuation, the need for a solid frame to retain the prestrain state is a limitation for the practical implementation of DEs, especially for active origami structures. However, the recent availability of thinner DE materials (50 μm, 130 μm, 260 μm) has made DEs a likely medium for active origami. In this work, the folding and unfolding of DE multilayered structures, along with the realization of origami-inspired 3D shapes, are explored. In addition, an exhaustive study on the fundamentals of DE actuation is done by directly investigating the thickness actuation mechanism and comparing their performance using different electrode types. Finally, changes in dielectric permittivity as a function of strain, electrode type and applied electric field are assessed and analyzed. These fundamental studies are key to obtaining more dramatic folding and to realizing active origami structures using DE materials. (paper)

Butterfly valve torque prediction methodology

International Nuclear Information System (INIS)

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

1994-01-01

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

Highly-Integrated Hydraulic Smart Actuators and Smart Manifolds for High-Bandwidth Force Control

Directory of Open Access Journals (Sweden)

Victor Barasuol

2018-06-01

Full Text Available Hydraulic actuation is the most widely used alternative to electric motors for legged robots and manipulators. It is often selected for its high power density, robustness and high-bandwidth control performance that allows the implementation of force/impedance control. Force control is crucial for robots that are in contact with the environment, since it enables the implementation of active impedance and whole body control that can lead to a better performance in known and unknown environments. This paper presents the hydraulic Integrated Smart Actuator (ISA developed by Moog in collaboration with IIT, as well as smart manifolds for rotary hydraulic actuators. The ISA consists of an additive-manufactured body containing a hydraulic cylinder, servo valve, pressure/position/load/temperature sensing, overload protection and electronics for control and communication. The ISA v2 and ISA v5 have been specifically designed to fit into the legs of IIT’s hydraulic quadruped robots HyQ and HyQ-REAL, respectively. The key features of these components tackle 3 of today’s main challenges of hydraulic actuation for legged robots through: (1 built-in controllers running inside integrated electronics for high-performance control, (2 low-leakage servo valves for reduced energy losses, and (3 compactness thanks to metal additive manufacturing. The main contributions of this paper are the derivation of the representative dynamic models of these highly integrated hydraulic servo actuators, a control architecture that allows for high-bandwidth force control and their experimental validation with application-specific trajectories and tests. We believe that this is the first work that presents additive-manufactured, highly integrated hydraulic smart actuators for robotics.

Water hammer caused by closure of turbine safety spherical valves

Science.gov (United States)

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

2010-08-01

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

Water hammer caused by closure of turbine safety spherical valves

International Nuclear Information System (INIS)

Karadzic, U; Vukoslavcevic, P; Bergant, A

2010-01-01

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

Water hammer caused by closure of turbine safety spherical valves

Energy Technology Data Exchange (ETDEWEB)

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

2010-08-15

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

Light-Triggered Soft Artificial Muscles: Molecular-Level Amplification of Actuation Control Signals.

Science.gov (United States)

Dicker, Michael P M; Baker, Anna B; Iredale, Robert J; Naficy, Sina; Bond, Ian P; Faul, Charl F J; Rossiter, Jonathan M; Spinks, Geoffrey M; Weaver, Paul M

2017-08-23

The principle of control signal amplification is found in all actuation systems, from engineered devices through to the operation of biological muscles. However, current engineering approaches require the use of hard and bulky external switches or valves, incompatible with both the properties of emerging soft artificial muscle technology and those of the bioinspired robotic systems they enable. To address this deficiency a biomimetic molecular-level approach is developed that employs light, with its excellent spatial and temporal control properties, to actuate soft, pH-responsive hydrogel artificial muscles. Although this actuation is triggered by light, it is largely powered by the resulting excitation and runaway chemical reaction of a light-sensitive acid autocatalytic solution in which the actuator is immersed. This process produces actuation strains of up to 45% and a three-fold chemical amplification of the controlling light-trigger, realising a new strategy for the creation of highly functional soft actuating systems.

Switching sliding mode force tracking control of piezoelectric-hydraulic pump-based friction element actuation systems for automotive transmissions

Science.gov (United States)

Kim, Gi-Woo; Wang, K. W.

2009-08-01

In this study, a nonlinear sliding-mode controller is designed for force tracking of a piezoelectric-hydraulic pump (PHP)-based actuation system, which is developed to replace the current electro-hydraulic actuation systems for automatic transmission (AT) friction elements, such as band brakes or clutches. By utilizing the PHP, one can eliminate the various hydraulic components (oil pump, regulating valve and control valve) in current ATs and achieve a simpler configuration with more efficient operation. With the derived governing equation of motion of the PHP-based actuation system integrated with the friction element (band brake), a switching control law is synthesized based on the sliding-mode theory. To evaluate the effectiveness of the proposed control law, its force tracking performance for the engagement of a friction element during an AT 1\\to 2 up-shift is examined experimentally. It is shown that one can successfully track the desired force trajectory for AT shift control with small tracking error. This study demonstrates the potential of the PHP as a new controllable actuation system for AT friction elements.

Switching sliding mode force tracking control of piezoelectric-hydraulic pump-based friction element actuation systems for automotive transmissions

International Nuclear Information System (INIS)

Kim, Gi-Woo; Wang, K W

2009-01-01

In this study, a nonlinear sliding-mode controller is designed for force tracking of a piezoelectric-hydraulic pump (PHP)-based actuation system, which is developed to replace the current electro-hydraulic actuation systems for automatic transmission (AT) friction elements, such as band brakes or clutches. By utilizing the PHP, one can eliminate the various hydraulic components (oil pump, regulating valve and control valve) in current ATs and achieve a simpler configuration with more efficient operation. With the derived governing equation of motion of the PHP-based actuation system integrated with the friction element (band brake), a switching control law is synthesized based on the sliding-mode theory. To evaluate the effectiveness of the proposed control law, its force tracking performance for the engagement of a friction element during an AT 1→2 up-shift is examined experimentally. It is shown that one can successfully track the desired force trajectory for AT shift control with small tracking error. This study demonstrates the potential of the PHP as a new controllable actuation system for AT friction elements

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

Science.gov (United States)

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

2015-06-01

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

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

Science.gov (United States)

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

2015-03-01

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

Development of hydraulic brake actuator for active brake control; Active brake seigyoyo yuatsu booster no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Konishi, Y; Hattori, M. Sugisawa, M.; Nishii, M [Aisin Seiki Co. Ltd., Aichi (Japan)

1997-10-01

Recently, application of active brake control systems of the vehicle are increasing. (Vehicle stability control, Panic brake assist ) We have developed a new hydraulic brake actuator for active brake control systems. New hydraulic brake actuator is composed of the three parts. (Hydraulic booster unit, Power supply unit, Control valve unit) This report describes the construction of the new hydraulic booster unit. 2 refs., 10 figs.

A piezoelectric micro control valve with integrated capacitive sensing for ambulant blood pressure waveform monitoring

Science.gov (United States)

Groen, Maarten S.; Wu, Kai; Brookhuis, Robert A.; van Houwelingen, Marc J.; Brouwer, Dannis M.; Lötters, Joost C.; Wiegerink, Remco J.

2014-12-01

We have designed and characterized a MEMS microvalve with built-in capacitive displacement sensing and fitted it with a miniature piezoelectric actuator to achieve active valve control. The integrated displacement sensor enables high bandwidth proportional control of the gas flow through the valve. This is an essential requirement for non-invasive blood pressure waveform monitoring based on following the arterial pressure with a counter pressure. Using the capacitive sensor, we demonstrate negligible hysteresis in the valve control characteristics. Fabrication of the valve requires only two mask steps for deep reactive ion etching (DRIE) and one release etch.

A piezoelectric micro control valve with integrated capacitive sensing for ambulant blood pressure waveform monitoring

International Nuclear Information System (INIS)

Groen, Maarten S; Wu, Kai; Brookhuis, Robert A; Lötters, Joost C; Wiegerink, Remco J; Van Houwelingen, Marc J; Brouwer, Dannis M

2014-01-01

We have designed and characterized a MEMS microvalve with built-in capacitive displacement sensing and fitted it with a miniature piezoelectric actuator to achieve active valve control. The integrated displacement sensor enables high bandwidth proportional control of the gas flow through the valve. This is an essential requirement for non-invasive blood pressure waveform monitoring based on following the arterial pressure with a counter pressure. Using the capacitive sensor, we demonstrate negligible hysteresis in the valve control characteristics. Fabrication of the valve requires only two mask steps for deep reactive ion etching (DRIE) and one release etch. (paper)

Miniaturization of a Quasi-Servo Valve and Its Application to Positon Control of a Rubber Artificial Muscle with Built-in Sensor

Directory of Open Access Journals (Sweden)

Moriwake Yoshinori

2016-01-01

Full Text Available Nowadays, the care and welfare pneumatic devices to support a nursing care and a self-reliance of the elderly and the disabled are actively researched and developed by many researchers. These wearable devices require many actuators and control valves for multi degrees of freedom. The total weight and volume of the wearable devices increases according to the degree of freedom. Our final goal is to develop a compact wearable actuator with built-in sensor, controller and control valve and to apply it to a wearable assisted device. In our previous study, a small-sized quasi-servo valve which consists of two on/off control valves and an embedded controller was developed. In this study, the quasi-servo valve composing of much smaller-sized (40% in mass, 42% in volume on/off valves is proposed and tested. In addition, the rubber artificial muscle with an ultrasonic sensor as a built-in displacement sensor is proposed and a position control of the muscle is carried out using the tested tiny valve and built-in sensor. As a result, it was confirmed that the position control of the muscle can be realized using the tested ultrasonic sensor.

Analysis of the giant magnetostrictive actuator with strong bias magnetic field

Energy Technology Data Exchange (ETDEWEB)

Xue, Guangming, E-mail: yy0youxia@163.com; He, Zhongbo; Li, Dongwei; Yang, Zhaoshu; Zhao, Zhenglong

2015-11-15

Giant magnetostrictive actuator with strong bias magnetic field is designed to control the injector bullet valve opening and closing. The relationship between actuator displacement amplitude and input signal direction is analyzed. And based on the approximate linearity of strain-magnetic field, second-order system model of the actuator displacement is established. Experimental system suitable for the actuator is designed. The experimental results show that, the square voltage amplitude being 12 V, the actuator displacement amplitude is about 17 μm with backward direction signal input while being 1.5 μm under forward direction signal. From the results, the suitable input direction is confirmed to be backward. With exciting frequncy lower than 200 Hz, the error between the model and experimental result is less than 1.7 μm. So the model is validated under the low-frequency signal input. The testing displacement-voltage curves are approximately straight lines. But due to the biased position, the line slope and the displacement-voltage linearity change as the input voltage changes. - Highlights: • Giant magnetostrictive actuator with strong bias magnetic field is designed. • The relationship between actuator displacement amplitude and input current direction is analyzed. • The model of the actuator displacement is established and its accuracy is verified by the test. • The actuator displacement-voltage curves are achieved by the test, and the curves’ characteristics are analyzed theoretically.

Lifetime of piezoceramic multilayer actuators : interplay of material properties and actuator design

NARCIS (Netherlands)

Ende, D.A. van den; Bos, B.; Groen, W.A.; Dortmans, L.M.J.G.

2009-01-01

We report an investigation into factors limiting the functional lifetime of multilayer piezoceramic actuators. The study consists of a combination of lifetime experiments by means of an accelerated lifetime test, inspection of the actuator microstructure at different stages of the accelerated

Advancements in valve technology and industry lessons lead to improved plant reliability and cost savings

International Nuclear Information System (INIS)

Sharma, V.; Kalsi, M.S.

2005-01-01

Plant reliability and safety hinges on the proper functioning of several valves. Recent advancements in valve technology have resulted in new analytical and test methods for evaluating and improving valve and actuator reliability. This is especially significant in critical service applications in which the economic impact of a valve failure on production, outage schedules and consequential damages far surpasses the initial equipment purchase price. This paper presents an overview of recent advances in valve technology driven by reliability concerns and cost savings objectives without comprising safety in the Nuclear Power Industry. This overview is based on over 27 years of experience in supporting US and International nuclear power utilities, and contributing to EPRI, and NSSS Owners' Groups in developing generic models/methodologies to address industry wide issues; performing design basis reviews; and implementing plant-wide valve reliability improvement programs. Various analytical prediction software and hardware solutions and training seminars are now available to implement valve programs covering power plants' lifecycle from the construction phase through life extension and power up rate. These tools and methodologies can enhance valve-engineering activities including the selection, sizing, proper application, condition monitoring, failure analysis, and condition based maintenance optimization with a focus on potential bad actors. This paper offers two such examples, the Kalsi Valve and Actuator Program (KVAP) and Check Valve Analysis and Prioritization (CVAP) [1-3, 8, 9, 11-13]. The advanced, validated torque prediction models incorporated into KVAP software for AOVs and MOVs have improved reliability of margin predictions and enabled cost savings through elimination of unwarranted equipment modifications. CVAP models provides a basis to prioritize the population of valves recommended for preventive maintenance, inspection and/or modification, allowing

Zipping dielectric elastomer actuators: characterization, design and modeling

International Nuclear Information System (INIS)

Maffli, L; Rosset, S; Shea, H R

2013-01-01

We report on miniature dielectric elastomer actuators (DEAs) operating in zipping mode with an analytical model that predicts their behavior. Electrostatic zipping is a well-known mechanism in silicon MEMS to obtain large deformations and forces at lower voltages than for parallel plate electrostatic actuation. We extend this concept to DEAs, which allows us to obtain much larger out-of-plane displacements compared to silicon thanks to the softness of the elastomer membrane. We study experimentally the effect of sidewall angles and elastomer prestretch on 2.3 mm diameter actuators with PDMS membranes. With 15° and 22.5° sidewall angles, the devices zip in a bistable manner down 300 μm to the bottom of the chambers. The highly tunable bistable behavior is controllable by both chamber geometry and membrane parameters. Other specific characteristics of zipping DEAs include well-controlled deflected shape, tunable displacement versus voltage characteristics to virtually any shape, including multi-stable modes, sealing of embedded holes or channels for valving action and the reduction of the operating voltage. These properties make zipping DEAs an excellent candidate for applications such as integrated microfluidics actuators or Braille displays. (paper)

Preventive maintenance measures and repeat tests on actuators

International Nuclear Information System (INIS)

Hueren, H.

1990-01-01

At Biblis Nuclear Power Station, about 1500 electrical actuators and variable speed drives of various model ranges and with various driving end speeds and actuating times are installed and about 600 of these are located in important safety engineering systems. In order to optimize the preventive maintenance measures on the drives, a data bank has been established into which are stored, in addition to the fixed type data of each drive, inter alia, statements about location of application, valve type, inspection cycle, calendar year of next maintenance, findings during inspection measures and causes of faults. Before each unit inspection, in addition to the inspection lists, the maintenance and installation records and also the associated job instructions are produced from this data processing equipment. (orig.) [de

The Otto-Atkinson engine. A study of fluid flow and combustion with early and late inlet valve closing

Energy Technology Data Exchange (ETDEWEB)

Haakansson, Henrik

1999-10-01

This report contains results of measurements on an Otto engine. The purpose for this work has been to do measurements of the flow in the cylinder but also measurements of the cylinder pressure have been performed. The flow measurements are made with the method Laser Doppler Velocimetry, LDV. The reason why these measurements are made at all are the pump losses that implies a lower efficiency for the Otto engine at part load. In this work two alternative ways that highly reduces the pump losses are examined. These are early inlet valve closing and late inlet valve closing. To further increase the efficiency at part load an increased compression ratio has been used together with the different valve strategies. With these two ways of operation, at a part load of about 4 - 5 IMEP{sub net}, increases of about 20% of the net indicated efficiency has been obtained. Additionally this report contains a chapter about the possible use of a variable valve actuation or timing system, VVA or VVT. Many conditions for the Otto cycle can be improved by the use of a variable valve actuation and in this chapter it is dealt with the most important ones.

Plunger with simple retention valve

International Nuclear Information System (INIS)

Fekete, A.V.

1987-01-01

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

The Klinger hot gas double axial valve

International Nuclear Information System (INIS)

Kruschik, J.; Hiltgen, H.

1984-01-01

The Klinger hot gas valve is a medium controlled double axial valve with advanced design features and safety function. It was first proposed by Klinger early in 1976 for the PNP-Project as a containment shut-off for hot helium (918 deg. C and 42 bar), because a market research has shown that such a valve is not state of present techniques. In the first stage of development a feasibility study had to be made by detailed design, calculation and by basic experiments for key components in close collaboration with Interatom/GHT. This was the basis for further design, calculation, construction and experimental work for such a valve prototype within the new development contract. The stage of knowledge to that time revealed the following key priority development areas: Finite element stress analysis for the highly stressed high temperature main components; development of an insulation layout; Detailed experimental tests of functionally important structural components or units of the valve, partly at Klingers (gasstatic bearings, flexible metallic sealing element, aerodynamic and thermohydraulic tests), partly at Interatom (actuator unit and also gasstatic bearings), partly at HRB in Juelich (flexible metallic sealing system, aerodynamic and thermohydraulic tests); Design of a test valve for experimental work in the KVK (test circuit at Interatom) for evaluation of temperature distribution and reliability of operation; Design of a prototype and extensive testing in the KVK

Seismic qualification of motor operated valves - alternate approach

International Nuclear Information System (INIS)

Bruck, P.M.; Eissa, M.A.

1998-01-01

This paper presents a potential alternate method for determining operating capacity of motor-operated valves subjected to seismic and other applicable loadings. As a result of programs at nuclear facilities to ensure the operational capability of MOVs (under NRC GL89-10), extensive analytical focus to develop the structural capability of valves has ensued. In the past, seismic qualification of valves typically addressed the strength of the topwork structure to resist inertial loading from excitation of the large valve actuator mass. These evaluations paid little or no consideration to the loading resulting from valve closing forces. The focus of the recent efforts is to develop the maximum operational capability of the valve, in terms of thrust, with consideration of seismic and other services loading as applicable. The alternate method outlined in this paper presents a series of thrust capacity curves, with reduction factors for seismic loading which can be applied and developed to determine safe thrust loadings without performing extensive analytical effort. A similar approach was put forward by the SQUG GIP approach to MOVs to ensure the safe operation of valves based on past earthquake experience. However, the GIP approach cannot be used to determine safe operational loads and thus has limited use in the necessary analysis required for GL89-10 programs at nuclear facilities. (orig.)

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

International Nuclear Information System (INIS)

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

1995-01-01

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

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

Science.gov (United States)

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

2018-01-01

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

Parallel kinematic mechanisms for distributed actuation of future structures

Science.gov (United States)

Lai, G.; Plummer, A. R.; Cleaver, D. J.; Zhou, H.

2016-09-01

Future machines will require distributed actuation integrated with load-bearing structures, so that they are lighter, move faster, use less energy, and are more adaptable. Good examples are shape-changing aircraft wings which can adapt precisely to the ideal aerodynamic form for current flying conditions, and light but powerful robotic manipulators which can interact safely with human co-workers. A 'tensegrity structure' is a good candidate for this application due to its potentially excellent stiffness and strength-to-weight ratio and a multi-element structure into which actuators could be embedded. This paper presents results of an analysis of an example practical actuated tensegrity structure consisting of 3 ‘unit cells’. A numerical method is used to determine the stability of the structure with varying actuator length, showing how four actuators can be used to control movement in three degrees of freedom as well as simultaneously maintaining the structural pre-load. An experimental prototype has been built, in which 4 pneumatic artificial muscles (PAMs) are embedded in one unit cell. The PAMs are controlled antagonistically, by high speed switching of on-off valves, to achieve control of position and structure pre-load. Experimental and simulation results are presented, and future prospects for the approach are discussed.

Stepper Motor Actuated Microvalve

Energy Technology Data Exchange (ETDEWEB)

Fazal, Imran; Louwerse, Marcus; Jansen, Henri; Elwenspoek, Miko [MESA Research Institute, University of Twente EWI/TST, P. off Box 217 Enschede (Netherlands)

2006-04-01

We present the design, fabrication and characterization of a novel microvalve realized by combining micro and fine machining techniques. The design is for high flow rates at high pressure difference between inlet and outlet, burst pressure of up to 15 bars, there is no power consumption required for the valve to maintain its position during operation in any intermediate state and the process gas does not interact with the actuation mechanism. The microvalve was experimentally characterized with airflows. It is shown that flow rates of 220 ml/min at a pressure difference of 4 bars could be achieved with the minimum accurate flow rate of 2-8 ml/min.

Evaluation of the flow forces on an open centre directional control valve by means of a computational fluid dynamic analysis

International Nuclear Information System (INIS)

Amirante, R.; Del Vescovo, G.; Lippolis, A.

2006-01-01

The aim of the present paper is the evaluation of the driving forces acting on a 4/3 hydraulic open center directional control valve spool by means of a complete numerical analysis. In a previous paper by the same authors, the valve was inserted in a closed hydraulic circuit and was tested with different pump flow rate values to obtain experimental results about the driving forces. The experimental results are used in this paper to evaluate and validate the numerical analysis of the valve. The obtained numerical results show important differences between an open center valve and a closed center one, the latter being extensively analyzed in the literature. The numerical analysis is performed by using the commercial code 'Fluent', and the numerical results show the complete flow field inside the valve. The aim of this analysis is to evaluate the valve fluid dynamic performance, exploiting computational fluid dynamics (CFD) techniques, in order to give the reliable indications needed to define the valve design criteria and avoid expensive experimental tests

Characterization of a piezoelectric valve for an adaptive pneumatic shock absorber

International Nuclear Information System (INIS)

Mikułowski, Grzegorz; Wiszowaty, Rafał; Holnicki-Szulc, Jan

2013-01-01

This paper describes a pneumatic valve based on a multilayer piezoelectric actuator and Hörbiger plates. The device was designed to operate in an adaptive pneumatic shock absorber. The adaptive pneumatic shock absorber was considered as a piston–cylinder device and the valve was intended to be installed inside the piston. The main objective for the valve application was regulating the gas flow between the cylinder’s chambers in order to maintain the desired value of the reaction force generated by the shock absorber. The paper describes the design constraints and requirements, together with results of analytical modelling of fluid flow verified versus experimentally obtained data. The presented results indicate that the desired performance characteristics of the valve were obtained. The geometrical constraints of the flow ducts were studied and the actuator’s functional features analysed. (paper)

Characterization of a piezoelectric valve for an adaptive pneumatic shock absorber

Science.gov (United States)

Mikułowski, Grzegorz; Wiszowaty, Rafał; Holnicki-Szulc, Jan

2013-12-01

This paper describes a pneumatic valve based on a multilayer piezoelectric actuator and Hörbiger plates. The device was designed to operate in an adaptive pneumatic shock absorber. The adaptive pneumatic shock absorber was considered as a piston-cylinder device and the valve was intended to be installed inside the piston. The main objective for the valve application was regulating the gas flow between the cylinder’s chambers in order to maintain the desired value of the reaction force generated by the shock absorber. The paper describes the design constraints and requirements, together with results of analytical modelling of fluid flow verified versus experimentally obtained data. The presented results indicate that the desired performance characteristics of the valve were obtained. The geometrical constraints of the flow ducts were studied and the actuator’s functional features analysed.

Using torque switch settings and spring pack characteristics to determine actuator output torques

International Nuclear Information System (INIS)

Black, B.R.

1992-01-01

Actuator output torque of motor operated valves is often a performance parameter of interest. It is not always possible to directly measure this torque. Torque spring pack deflection directly reflects actuator output torque and can be directly measured on most actuators. The torque spring pack may be removed from the actuator and tested to determine its unique force-deflection relationship. Or, a representative force-deflection relationship for the particular spring pack model may be available. With either relationship, measurements of torque spring pack deflection may then be correlated to corresponding forces. If the effective length of the moment arm within the actuator is known, actuator output torque can then be determined. The output torque is simply the product of the effective moment arm length and the spring pack force. This paper presents the reliability of this technique as indicated by testing. TU Electric is evaluating this technique for potential use in the future. Results presented in this paper should be considered preliminary. Applicability of these results may be limited to actuators and their components in a condition similar to those for which test data have been examined

Assessing the efficiency of automatically controlled valves (ACV) for pipeline sectioning

Energy Technology Data Exchange (ETDEWEB)

Veiga, Leandro S. da; Silva, Marcos J.M. da; Leite, Joao Paulo de B.; Santos, Renata N.R. dos; Jardim, Rodrigo B.O.; Quinto, Thiago C. do [Petrobras Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil)

2009-07-01

In order to mitigate the effects caused by the rupture of a gas pipeline and following ASME B 31.8 recommendations, block valves are installed in these structures. However, many transportation companies also install devices capable of infer the occurrence of an accident in a gas pipeline. The most common devices are the ones that actuate when pressure in gas pipeline reaches a low value early established (PSL) and those which close valves due to high rate of pressure drop (line-break). Line-break has the function of identifying as fast as possible the occurrence of a rupture in a gas pipeline by high rate of pressure drop in that line. Although PSL presents a later actuation when compared to the line break, it represents redundancy to the line-break system, since it is able to isolate the segment where the accident happened even if other devices or the operator had not done it before. The growing of gas pipelines transport capacity has been generated transients capable of causing an erroneous shut down of the shut down valves (SDV). The aim of this paper, therefore, is to present how the operational limits of SDV can be overcome with remote operation using SCADA System. (author)

Main feedwater valve diagnostics at Waterford 3 nuclear generating station

International Nuclear Information System (INIS)

Fitzgerald, W.V.

1991-01-01

Pneumatically-operated control valves are coming under increasing scrutiny in nuclear power plants because of their relatively high incident rate. The theory behind a device that could make performance evaluation of these valves simpler and more effective was first described at the original EPRI Power Plant Valve Symposium. The development of this Diagnostic System was completed in 1989, and it was recently used to troubleshoot two main feedwater valves at Louisiana Power and Light's Waterford 3 Power Station. During a cold snap last December, these valves failed to respond to the input signal and, as a result, the plant came off line. An incident report had to be filed, and the plant chose to contact the original equipment manufacturer (OEM) for assistance. This paper describes the original incident involving these valves and then gives a brief description of the diagnostic system and how it works. The balance of the paper then reviews how the OEM and plant personnel utilized the system to evaluate each component of the control valve assembly (I/P transducer, positioner, volume boosters, actuator, and valve body assembly). By simply stroking the valve and monitoring pneumatic signals and valve position, the problem was traced to a malfunctioning positioner and a volume booster that was leaking. The problems were corrected and new performance signatures run for the valves using the system to document their improved operation. This case study demonstrates how new Diagnostic Technology along with OEM involvement can effectively address problems with pneumatically-operated control valves so that root-cause solutions can be implemented

Safety relief valve alternate analysis method

International Nuclear Information System (INIS)

Adams, R.H.; Javid, A.; Khatua, T.P.

1981-01-01

An experimental test program was started in the United States in 1976 to define and quantify Safety Relief Valve (SRV) phenomena in General Electric Mark I Suppression Chambers. The testing considered several discharged devices and was used to correlate SRV load prediction models. The program was funded by utilities with Mark I containments and has resulted in a detailed SRV load definition as a portion of the Mark I containment program Load Definition Report (LDR). The (USNRC) has reviewed and approved the LDR SRV load definition. In addition, the USNRC has permitted calibration of structural models used for predicting torus response to SRV loads. Model calibration is subject to confirmatory in-plant testing. The SRV methodology given in the LDR requires that transient dynamic pressures be applied to a torus structural model that includes a fluid added mass matrix. Preliminary evaluations of torus response have indicated order of magnitude conservatisms, with respect to test results, which could result in unrealistic containment modifications. In addition, structural response trends observed in full-scale tests between cold pipe, first valve actuation and hot pipe, subsequent valve actuation conditions have not been duplicated using current analysis methods. It was suggested by others that an energy approach using current fluid models be utilized to define loads. An alternate SRV analysis method is defined to correct suppression chamber structural response to a level that permits economical but conservative design. Simple analogs are developed for the purpose of correcting the analytical response obtained from LDR analysis methods. Analogs evaluated considered forced vibration and free vibration structural response. The corrected response correlated well with in-plant test response. The correlation of the analytical model at test conditions permits application of the alternate analysis method at design conditions. (orig./HP)

Modification and performance evaluation of a mono-valve engine

Science.gov (United States)

Behrens, Justin W.

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

Diseases of the Tricuspid Valve

Science.gov (United States)

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

Recent experience with testing of parallel disc gate valves under accident flow conditions

International Nuclear Information System (INIS)

LaPointe, P.A.; Clayton, J.K.

1992-01-01

This paper presents the nuclear valve industry's latest and most extensive valve qualification test program experience. The test program includes a variety of 25 different gate and globe valves. All the test valves are power operated using either air, electric, or gas/hydraulic operators. The valves are categorized in size and pressure class so as to form a group of appropriate parent valve assemblies. Parent valve assembly qualification is used as the basis for qualification of candidate valve assemblies. The parent and candidate valve assemblies are representative of a nuclear plant's safety-related valve applications. The test program was performed in accordance with ANSI B16.41-1983 'Functional Qualification Requirements for Power Operated Active Valve Assemblies for Nuclear Power Plants.' The focus of this paper is on functional valve qualification test experience and specifically flow interruption testing to Annex G of the aforementioned test standard. Results of the flow test are summarized, including the coefficient of friction for each of the gate type valves reported. Information on valve size, pressure class, and actuator are given for all valves in the program. Although all valves performed extremely well, only selected test data are presented. The effects of the speed of operation and the effects of different fluid flow rates as they relate to the coefficient of friction between the valve disc and seat are discussed. The variation in the coefficient of friction based on other variables in the thrust equation, namely, differential pressure area is cited

Automation Activator of Hydrogen Gas Inlet Valve on Reduction Furnace ME-11

International Nuclear Information System (INIS)

Achmad Suntoro

2007-01-01

Operational of hydrogen inlet valve of the reduction furnace ME-11 was actuated manually by furnace operator if all its requirements have been fulfilled. Automation of the valve has been constructed as an additional option of the furnace operating system, in which any interruption by the existing manual system by the operator is still valid even though the automatic option is being used. This paper describes the information concerning the automation construction and its logical status of control in the form of its finite state machine. This automation system has been tested successfully. (author)

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

Science.gov (United States)

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

2017-02-15

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

Initial data collection efforts of CREDO. Sodium valve failures

International Nuclear Information System (INIS)

Bott, T.F.; Haas, P.M.

1978-01-01

The Centralized Reliability Data organisation (CREDO) has been established at Oak Ridge National Laboratory to define, develop, and maintain a reliability data analysis center for use in advanced reactor safety and licensing. Its primary functions are collection, reduction, evaluation, storage, retrieval, and dissemination of reliability/maintainability data. Data-collection efforts have been initiated at several test loops, at the Experimental Breeder Reactor-II and at the Fast Flux Test Facility. Top priority is being given to collection data on safety and safety-related systems, primarily for sodium-cooled reactors. Sufficient operating time has been accumulated on sodium valves at test facilities to provide quantitative estimates of reliability characteristics with a reasonable degree of confidence. Sodium-valve failures have been categorized according to seat design, size, seal type, and actuator type. Attempts have been made to establish the variation of failure rate with time and duty. Estimates of failure rates for sodium valves have been compared to those for water valves and appear to be of the same order of magnitude. (author)

Design and performance analysis of position-based impedance control for an electrohydrostatic actuation system

Directory of Open Access Journals (Sweden)

Yongling FU

2018-03-01

Full Text Available Electrohydrostatic actuator (EHA is a type of power-by-wire actuator that is widely implemented in the aerospace industry for flight control, landing gears, thrust reversers, thrust vector control, and space robots. This paper presents the development and evaluation of position-based impedance control (PBIC for an EHA. Impedance control provides the actuator with compliance and facilitates the interaction with the environment. Most impedance control applications utilize electrical or valve-controlled hydraulic actuators, whereas this work realizes impedance control via a compact and efficient EHA. The structures of the EHA and PBIC are firstly introduced. A mathematical model of the actuation system is established, and values of its coefficients are identified by particle swarm optimization. This model facilitates the development of a position controller and the selection of target impedance parameters. A nonlinear proportional-integral position controller is developed for the EHA to achieve the accurate positioning requirement of PBIC. The controller compensates for the adverse effect of stiction, and a position accuracy of 0.08 mm is attained. Various experimental results are presented to verify the applicability of PBIC to the EHA. The compliance of the actuator is demonstrated in an impact test. Keywords: Actuation system, Aerospace, Electrohydrostatic actuator, Force control, Nonlinear dynamics, Particle swarm optimization, Position control

Clean room actuators

Energy Technology Data Exchange (ETDEWEB)

Higuchi, Toshiro

1987-06-01

This report explains on the present status of the clean room actuators including the author's research results. In a clean room, there exists a possibility of dust generation, even when a direct human work is eliminated by the use of robots or automatic machines, from the machines themselves. For this, it is important to develop such clean robots and transfer/positioning mechanism that do not generate dusts, and to develop an actuator and its control technique. Topics described in the report are as follows: 1. Prevention of dust diffusion by means of sealing. 2. Elimination of mechanical contact (Linear induction motor and pneumatic float, linear motor and magnetic attraction float, linear motor and air bearing, and magnetic bearing). 3. Contactless actuator having a positioning mechanism (Use of linear step motor and rotary contactless actuator). (15 figs, 11 refs)

Colombian experience with transcatheter aortic valve implantation of medtronic CoreValve.

Science.gov (United States)

Dager, Antonio E; Nuis, Rutger-Jan; Caicedo, Bernardo; Fonseca, Jaime A; Arana, Camilo; Cruz, Lidsa; Benitez, Luis M; Nader, Carlos A; Duenas, Eduardo; de Marchena, Eduardo J; O'Neill, William W; de Jaegere, Peter P

2012-01-01

At our institutions, increasing numbers of aortic stenosis patients were not candidates for surgical aortic valve replacement. Accordingly, we initiated the Cali Colombian Transcatheter Aortic Valve Implantation (TAVI) program. From March 2008 through January 2011, 53 consecutive patients (mean age, 79 ± 6 yr; men, 58%) underwent TAVI with the Medtronic CoreValve System, and data were prospectively collected. Our study's endpoints conformed with Valve Academic Research Consortium recommendations. We report our clinical results.Predicted mortality rates were 25% (interquartile range, 17%-34%) according to logistic EuroSCORE and 6% (interquartile range, 3%-8%) according to the Society of Thoracic Surgeons score. The 30-day mortality rate was 9% (3 intraprocedural deaths, 5 total). The combined 30-day safety endpoint was 30% (major vascular sequelae, 23%; life-threatening bleeding, 12%; myocardial infarction, 4%; major stroke, 4%; and acute kidney injury [stage 3], 2%). Eight patients (15%) required post-implantation balloon dilation and 2 (4%) required valve-in-valve implantation, for a technical device success rate of 77%. Mean peak transvalvular gradient decreased from 74 ± 29 to 17 ± 8 mmHg and mean transvalvular gradient from 40 ± 17 to 8 ± 4 mmHg (both P=0.001). Moderate or severe aortic regurgitation decreased from 32% to 18% (P=0.12) and mitral regurgitation from 32% to 13% (P=0.002). The 1-year survival rate was 81%.We found that TAVI with the CoreValve prosthesis was safe and feasible, with sustained long-term results, for treating aortic stenosis in patients at excessive surgical risk; nonetheless, serious adverse events occurred in 30% of the patients.

Robust PID Controller for a Pneumatic Actuator

Directory of Open Access Journals (Sweden)

Skarpetis Michael G.

2016-01-01

Full Text Available In this paper the position control pneumatic actuator using a robust PID controller is presented. The parameters of the PID controller are computed using a Hurwitz invariability technique enriched with a Simulated Annealing Algorithm. The nonlinear model involves uncertain parameters due to linearization of the servo valve, variations of the initial volume of the cylinder and variation of the external load. The problem is proven to be solvable and the controller parameters are chosen to provide a suboptimal solution for tracking error minimization. Simulation results are presented for the nonlinear model.

A Computational Study on Hydrodynamic Torque Coefficients of a Butterfly Valve

International Nuclear Information System (INIS)

Lee, Do-Hwan; Park, Sung-Keun; Kang, Shin-Chul; Kim, Dae-Woong; Park, Ju-Yeop

2007-01-01

Butterfly valves have been widely used for on-off or control purposes in the process industry, since they provide quick opening and closing operation and good flow control characteristics. For the evaluation of the adequacy of valve operability and the actuator sizing, the required torque estimation is necessary. Since the principal contributing component of the require torque in the mid-stroke position is hydrodynamic torque, it is necessary to predict the torque properly under the actual flow conditions. The research on the prediction of the valve performance was led by EPRI (Electric Power Research Institute) in early 1990s. A performance prediction model was developed based on the experimental results and the free-streamline analysis by Sarpkaya. Recently, Kalsi Engineering carried out extended tests and developed the improved model. Variation of disk geometries and upstream flow conditions were tried to obtain accurate hydrodynamic torque coefficients. However, since the model is only commercially available, a general method to obtain hydrodynamic torque for butterfly valves is called for

V-stack piezoelectric actuator

Science.gov (United States)

Ardelean, Emil V.; Clark, Robert L.

2001-07-01

Aeroelastic control of wings by means of a distributed, trailing-edge control surface is of interest with regards to maneuvers, gust alleviation, and flutter suppression. The use of high energy density, piezoelectric materials as motors provides an appealing solution to this problem. A comparative analysis of the state of the art actuators is currently being conducted. A new piezoelectric actuator design is presented. This actuator meets the requirements for trailing edge flap actuation in both stroke and force. It is compact, simple, sturdy, and leverages stroke geometrically with minimum force penalties while displaying linearity over a wide range of stroke. The V-Stack Piezoelectric Actuator, consists of a base, a lever, two piezoelectric stacks, and a pre-tensioning element. The work is performed alternately by the two stacks, placed on both sides of the lever. Pre-tensioning can be readily applied using a torque wrench, obviating the need for elastic elements and this is for the benefit of the stiffness of the actuator. The characteristics of the actuator are easily modified by changing the base or the stacks. A prototype was constructed and tested experimentally to validate the theoretical model.

Application of hydraulic network analysis to motor operated butterfly valves in nuclear power plants

International Nuclear Information System (INIS)

Eldiwany, B.H.; Kalsi, M.S.

1992-01-01

This paper presents the application of hydraulic network analysis to evaluate the performance of butterfly valves in nuclear power plant applications. Required actuation torque for butterfly valves in high-flow applications is often dictated by peak dynamic torque. The peak dynamic torque, which occurs at some intermediate disc position, requires accurate evaluation of valve flow rate and pressure drop throughout the valve stroke. Valve flow rate and pressure drop are significantly affected by the valve flow characteristics and the hydraulic system characteristics, such as pumping capability, piping resistances, single and parallel flow paths, system hydrostatic pressure, and the location of the motor-operated valve (MOV) within the system. A hydraulic network analysis methodology that addresses the effect of these parameters on the MOV performance is presented. The methodology is based on well-established engineering principles. The application of this methodology requires detailed characteristics of both the MOV and the hydraulic system in which it is installed. The valve characteristics for this analysis can be obtained by flow testing or from the valve manufacturer. Even though many valve users, valve manufacturers, and engineering standards have recognized the importance of performing these analyses, none has provided a detailed procedure for doing so

Butterfly valve with metal seals controls flow of hydrogen from cryogenic through high temperatures

Science.gov (United States)

Johnson, L. D.

1967-01-01

Butterfly valve with metal seals operates over a temperature range of minus 423 degrees to plus 440 degrees F with hydrogen as a medium and in a radiation environment. Media flow is controlled by an internal butterfly disk which is rotated by an actuation shaft.

Multifunctional four-port directional control valve constructed from logic valves

International Nuclear Information System (INIS)

Lisowski, E.; Czyżycki, W.; Rajda, J.

2014-01-01

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

An investigation of the effects of pneumatic actuator design on slip control for heavy vehicles

Science.gov (United States)

Miller, Jonathan I.; Cebon, David

2013-01-01

Progress in reducing actuator delays in pneumatic brake systems is opening the door for advanced anti-lock braking algorithms to be used on heavy goods vehicles. However, little has been published on slip controllers for air-braked heavy vehicles, or the effects of slow pneumatic actuation on their design and performance. This paper introduces a sliding mode slip controller for air-braked heavy vehicles. The effects of pneumatic actuator delays and flow rates on stopping performance and air (energy) consumption are presented through vehicle simulations. Finally, the simulations are validated with experiments using a hardware-in-the-loop rig. It is shown that for each wheel, pneumatic valves with delays smaller than 3 ms and orifice diameters around 8 mm provide the best performance.

Experimental characterization of the hysteretic and rate-dependent electromechanical behavior of dielectric electro-active polymer actuators

International Nuclear Information System (INIS)

York, A; Seelecke, S; Dunn, J

2010-01-01

Dielectric electro-active polymers (DEAPs) can achieve substantial deformation (>300% strain) while sustaining, compared to their ionic counterparts, large forces. This makes them attractive for various actuation and sensing applications such as in light weight and energy efficient valve and pumping systems. Many applications operate DEAP actuators at higher frequencies where rate-dependent effects influence their performance. This motivates the seeking of dynamic characterization of these actuators beyond the quasi-static regime. This paper provides a systematic experimental investigation of the quasi-static and dynamic electromechanical properties of a DEAP actuator. In order to completely characterize the fully coupled behavior, force versus displacement measurements at various constant voltages and force versus voltage measurements at various fixed displacements are conducted. The experiments are conducted with a particular focus on the hysteretic and rate-dependent material behavior. These experiments provide insight into the electrical dynamics and viscoelastic relaxation inherent in DEAP actuators. This study is intended to provide information, including high frequency performance analysis, useful to anyone designing dynamic actuator systems using DEAPs

Pressure tracking control of vehicle ABS using piezo valve modulator

Science.gov (United States)

Jeon, Juncheol; Choi, Seung-Bok

2011-03-01

This paper presents a wheel slip control for the ABS(anti-lock brake system) of a passenger vehicle using a controllable piezo valve modulator. The ABS is designed to optimize for braking effectiveness and good steerability. As a first step, the principal design parameters of the piezo valve and pressure modulator are appropriately determined by considering the braking pressure variation during the ABS operation. The proposed piezo valve consists of a flapper, pneumatic circuit and a piezostack actuator. In order to get wide control range of the pressure, the pressure modulator is desired. The modulator consists of a dual-type cylinder filled with different substances (fluid and gas) and a piston rod moving vertical axis to transmit the force. Subsequently, a quarter car wheel slip model is formulated and integrated with the governing equation of the piezo valve modulator. A sliding mode controller to achieve the desired slip rate is then designed and implemented. Braking control performances such as brake pressure and slip rate are evaluated via computer simulations.

What caused the failures of the solenoid valve screws

International Nuclear Information System (INIS)

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

2001-01-01

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

A modelling study into the effects of variable valve timing on the gas exchange process and performance of a 4-valve DI homogeneous charge compression ignition (HCCI) engine

International Nuclear Information System (INIS)

Mahrous, A-F.M.; Potrzebowski, A.; Wyszynski, M.L.; Xu, H.M.; Tsolakis, A.; Luszcz, P.

2009-01-01

Homogeneous charge compression ignition (HCCI) combustion mode is a relatively new combustion technology that can be achieved by using specially designed cams with reduced lift and duration. The auto-ignition in HCCI engine can be facilitated by adjusting the timing of the exhaust-valve-closing and, to some extent, the timing of the intake-valve-opening so as to capture a proportion of the hot exhaust gases in the engine cylinder during the gas exchange process. The effects of variable valve timing strategy on the gas exchange process and performance of a 4-valve direct injection HCCI engine were computationally investigated using a 1D fluid-dynamic engine cycle simulation code. A non-typical intake valve strategy was examined; whereby the intake valves were assumed to be independently actuated with the same valve-lift profile but at different timings. Using such an intake valves strategy, the obtained results showed that the operating range of the exhaust-valve-timing within which the HCCI combustion can be facilitated and maintained becomes much wider than that of the typical intake-valve-timing case. Also it was found that the engine parameters such as load and volumetric efficiency are significantly modified with the use of the non-typical intake-valve-timing. Additionally, the results demonstrated the potential of the non-typical intake-valve strategy in achieving and maintaining the HCCI combustion at much lower loads within a wide range of valve timings. Minimizing the pumping work penalty, and consequently improving the fuel economy, was shown as an advantage of using the non-typical intake-valve-timing with the timing of the early intake valve coupled with a symmetric degree of exhaust-valve-closing timing

A modelling study into the effects of variable valve timing on the gas exchange process and performance of a 4-valve DI homogeneous charge compression ignition (HCCI) engine

Energy Technology Data Exchange (ETDEWEB)

Mahrous, A-F.M. [School of Mechanical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Lecturer at the Department of Mechanical Power Engineering, Faculty of Engineering (Shebin El-Kom), Menoufiya University, Shebin El-Kom (Egypt); Potrzebowski, A.; Wyszynski, M.L.; Xu, H.M.; Tsolakis, A.; Luszcz, P. [School of Mechanical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

2009-02-15

Homogeneous charge compression ignition (HCCI) combustion mode is a relatively new combustion technology that can be achieved by using specially designed cams with reduced lift and duration. The auto-ignition in HCCI engine can be facilitated by adjusting the timing of the exhaust-valve-closing and, to some extent, the timing of the intake-valve-opening so as to capture a proportion of the hot exhaust gases in the engine cylinder during the gas exchange process. The effects of variable valve timing strategy on the gas exchange process and performance of a 4-valve direct injection HCCI engine were computationally investigated using a 1D fluid-dynamic engine cycle simulation code. A non-typical intake valve strategy was examined; whereby the intake valves were assumed to be independently actuated with the same valve-lift profile but at different timings. Using such an intake valves strategy, the obtained results showed that the operating range of the exhaust-valve-timing within which the HCCI combustion can be facilitated and maintained becomes much wider than that of the typical intake-valve-timing case. Also it was found that the engine parameters such as load and volumetric efficiency are significantly modified with the use of the non-typical intake-valve-timing. Additionally, the results demonstrated the potential of the non-typical intake-valve strategy in achieving and maintaining the HCCI combustion at much lower loads within a wide range of valve timings. Minimizing the pumping work penalty, and consequently improving the fuel economy, was shown as an advantage of using the non-typical intake-valve-timing with the timing of the early intake valve coupled with a symmetric degree of exhaust-valve-closing timing. (author)

Aortic valve function after bicuspidization of the unicuspid aortic valve.

Science.gov (United States)

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

2013-05-01

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

Explosion-proof actuators according to EU directive 94/9/EC (ATEX)

Energy Technology Data Exchange (ETDEWEB)

Herbstritt, M. [AUMA Riester GmbH und Co. KG. Muellheim (Germany)

2004-07-01

Since July, 1, 2003 only explosion-proof devices which conform to the new EU Directive 94/9/EC, better known as the ATEX Directive, are introduced to the market. Especially the explosion protection of non-electrical equipment is a completely new task for many manufacturers. AUMA has qualified its electric actuators for the automation of industrial valves in accordance with the new regulations. In addition the design has been improved. (orig.)

A solar energy powered autonomous wireless actuator node for irrigation systems.

Science.gov (United States)

Lajara, Rafael; Alberola, Jorge; Pelegrí-Sebastiá, José

2011-01-01

The design of a fully autonomous and wireless actuator node ("wEcoValve mote") based on the IEEE 802.15.4 standard is presented. The system allows remote control (open/close) of a 3-lead magnetic latch solenoid, commonly used in drip irrigation systems in applications such as agricultural areas, greenhouses, gardens, etc. The very low power consumption of the system in conjunction with the low power consumption of the valve, only when switching positions, allows the system to be solar powered, thus eliminating the need of wires and facilitating its deployment. By using supercapacitors recharged from a specifically designed solar power module, the need to replace batteries is also eliminated and the system is completely autonomous and maintenance free. The "wEcoValve mote" firmware is based on a synchronous protocol that allows a bidirectional communication with a latency optimized for real-time work, with a synchronization time between nodes of 4 s, thus achieving a power consumption average of 2.9 mW.

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

Science.gov (United States)

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

2016-01-01

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

A novel energy-efficient rotational variable stiffness actuator

NARCIS (Netherlands)

Rao, S.; Carloni, Raffaella; Stramigioli, Stefano

This paper presents the working principle, the design and realization of a novel rotational variable stiffness actuator, whose stiffness can be varied independently of its output angular position. This actuator is energy-efficient, meaning that the stiffness of the actuator can be varied by keeping

Evaluation of steady flow torques and pressure losses in a rotary flow control valve by means of computational fluid dynamics

International Nuclear Information System (INIS)

Okhotnikov, Ivan; Noroozi, Siamak; Sewell, Philip; Godfrey, Philip

2017-01-01

Highlights: • A novel design of a rotary flow control valve driven by a stepper motor is proposed. • The intended use of the valve in the high flow rate independent metering hydraulic system is suggested. • Pressure drops, steady flow torques of the valve for various flow rates and orifice openings are studied by means of computational fluid dynamics. • The discharge coefficient and flow jet angles dependencies on the orifice opening are obtained. • A design method to decrease the flow forces without reducing the flow rate in single-staged valves is demonstrated. - Abstract: In this paper, a novel design of a rotary hydraulic flow control valve has been presented for high flow rate fluid power systems. High flow rates in these systems account for substantial flow forces acting on the throttling elements of the valves and cause the application of mechanically sophisticated multi-staged servo valves for flow regulation. The suggested design enables utilisation of single-stage valves in power hydraulics operating at high flow rates regimes. A spool driver and auxiliary mechanisms of the proposed valve design were discussed and selection criteria were suggested. Analytical expressions for metering characteristics as well as steady flow torques have been derived. Computational fluid dynamics (CFD) analysis of steady state flow regimes was conducted to evaluate the hydraulic behaviour of the proposed valve. This study represents a special case of an independent metering concept applied to the design of power hydraulic systems with direct proportional valve control operating at flow rates above 150 litres per minute. The result gained using parametric CFD simulations predicted the induced torque and the pressure drops due to a steady flow. Magnitudes of these values prove that by minimising the number of spool's mobile metering surfaces it is possible to reduce the flow-generated forces in the new generation of hydraulic valves proposed in this study

Control Valve Stiction Identification, Modelling, Quantification and Control - A Review

Directory of Open Access Journals (Sweden)

Srinivasan Arumugam

2011-09-01

Full Text Available Most of the processes found in process industries exhibit undesirable nonlinearity due to backlash, saturation, hysteresis, stiction (friction, dead-zone and stuck-fault existing in control valves. The control valve is the actuator for most process control loops and, as the only moving part in the loop, its function is to implement the control action. If the control valve malfunctions, the performance of the control loop is likely to deteriorate, no matter how good the controller is. Commonly encountered control valve problems include nonlinear responses to the demand signal caused by effects such as stiction, dead-band or saturation. Because of these problems, the control loop may be oscillatory, which in turn may cause oscillations in many process variables causing a range of operational problems including increased valve wear. Understanding nonlinear behaviour of control valves in order to maintain the quality of the end products in the industry, this review article surveys the identification, modelling, estimation and design of dynamic models of stiction nonlinearity and providing appropriate controller to obtain optimum responses of the process. The primary objective of this work is to present state-of-art-review of common nonlinear problems associated with mechanical and chemical processes for encouraging researchers, practicing engineers working in this field, so that readers can invent their goals for future research work on nonlinear systems identification and control.

Regression in left ventricular mass after aortic valve replacement for chronic aortic regurgitation is unrelated to prosthetic valve size.

Science.gov (United States)

Brown, Morgan L; Schaff, Hartzell V; Suri, Rakesh M; Li, Zhuo; Sundt, Thoralf M; Dearani, Joseph A; Enriquez-Sarano, Maurice

2011-08-01

We examined the role of prosthesis-patient mismatch on left ventricular mass regression after aortic valve replacement for chronic aortic valve regurgitation. We selected patients who had complete preoperative and follow-up echocardiograms with measurement of left ventricular mass. Patients were excluded who had moderate or greater aortic valve stenosis, concomitant coronary artery bypass grafting, or mitral valve procedures. Patients' mean age was 55 ± 17 years; 21% were female. The mean preoperative indexed left ventricular mass was 150 ± 45 g/m(2). Patients with mildly (n = 44; mean indexed mass, 126 ± 15 g/m(2)), moderately (n = 31; mean indexed mass, 168 ± 11 g/m(2)), or severely (n = 15; mean indexed mass, 241 ± 34 g/m(2)) increased preoperative indexed left ventricular mass, were similar, except for lower ejection fractions, larger end-diastolic dimensions, and larger ventricular wall thicknesses in the severely enlarged group (P regression was unrelated to labeled valve size, prosthesis-patient mismatch, or measured indexed effective aortic valve area. A greater preoperative indexed left ventricular mass (P regression. Despite having greater left ventricular mass regression, patients with severe preoperative indexed left ventricular mass did not return to normal values (mean, 142 ± 25 g/m(2)). Left ventricular mass regression after aortic valve replacement for chronic aortic regurgitation is unrelated to indexed prosthetic valve area. Although incomplete, regression is greatest in patients with the largest preoperative indexed left ventricular mass. Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

The effects of additives on the actuating performances of a dielectric elastomer actuator

International Nuclear Information System (INIS)

Nguyen, Huu Chuc; Doan, Vu Thuy; Park, JongKil; Koo, Ja Choon; Choi, Hyouk Ryeol; Lee, Youngkwan; Nam, Jae-do

2009-01-01

This paper presents a comprehensive study of the effects of additives on the performance of a dielectric elastomer actuator. Previously, a new dielectric elastomer material, called 'synthetic elastomer', was presented for the means of actuation, which permits changes in the mechanical as well as the electrical properties in order to meet the requirements of certain applications. This work studies how the electromechanical properties of the synthetic elastomer can be adjusted by combining two additives, namely dioctyl phthalate (DOP) and titanium dioxide (TiO 2 ). Experiments are carried out and the effects of each additive are compared to one another based on the actuation performances

Magnetic Actuation Connector Between Extension Shaft and Armature for Bottom Mounted Control Rod Drive Mechanism

Energy Technology Data Exchange (ETDEWEB)

Huh, Hyung; Cho, Yeong Garp; Kim, Jong In [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

The electromagnet and armature inside the guide tube interact and produce magnetism, thus making the armature, connecting extension shaft and control rod move up and down to control the power of reactor. During the overhaul, the control absorber rod (CAR), extension shaft, and armature of BMCRDM are lifted together for closing a seal valve. But total length of CAR assembly is so long that it cannot be lifted due to exposure above the water level of pool which is strictly controlled. In addition to this, it is difficult to calibrate a position indicator and lifting force of electromagnet without armature assembly as a seal valve is closed. For this reason, it is necessary to install a disconnecting system between armature and extension shaft. Therefore, KAERI has developed magnetic actuation connector using plunger between armature and extension shaft for the bottom mounted control rod drive mechanism in research reactor. The results of a FEM and the experiments in this work lead to the following conclusions: The FEM result for the design of the magnetic actuation connector is compared with the measured lifting force of prototype production. As a result, it is shown that the lifting force of the prototype connector has a good agreement with the result of the FEM. A newly developed technique of prototype magnetic actuation connector which is designed by FEM analysis result is proposed.

Magnetic Actuation Connector Between Extension Shaft and Armature for Bottom Mounted Control Rod Drive Mechanism

International Nuclear Information System (INIS)

Huh, Hyung; Cho, Yeong Garp; Kim, Jong In

2013-01-01

The electromagnet and armature inside the guide tube interact and produce magnetism, thus making the armature, connecting extension shaft and control rod move up and down to control the power of reactor. During the overhaul, the control absorber rod (CAR), extension shaft, and armature of BMCRDM are lifted together for closing a seal valve. But total length of CAR assembly is so long that it cannot be lifted due to exposure above the water level of pool which is strictly controlled. In addition to this, it is difficult to calibrate a position indicator and lifting force of electromagnet without armature assembly as a seal valve is closed. For this reason, it is necessary to install a disconnecting system between armature and extension shaft. Therefore, KAERI has developed magnetic actuation connector using plunger between armature and extension shaft for the bottom mounted control rod drive mechanism in research reactor. The results of a FEM and the experiments in this work lead to the following conclusions: The FEM result for the design of the magnetic actuation connector is compared with the measured lifting force of prototype production. As a result, it is shown that the lifting force of the prototype connector has a good agreement with the result of the FEM. A newly developed technique of prototype magnetic actuation connector which is designed by FEM analysis result is proposed

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Corrugated paraffin nanocomposite films as large stroke thermal actuators and self-activating thermal interfaces.

Science.gov (United States)

Copic, Davor; Hart, A John

2015-04-22

High performance active materials are of rapidly growing interest for applications including soft robotics, microfluidic systems, and morphing composites. In particular, paraffin wax has been used to actuate miniature pumps, solenoid valves, and composite fibers, yet its deployment is typically limited by the need for external volume constraint. We demonstrate that compact, high-performance paraffin actuators can be made by confining paraffin within vertically aligned carbon nanotube (CNT) films. This large-stroke vertical actuation is enabled by strong capillary interaction between paraffin and CNTs and by engineering the CNT morphology by mechanical compression before capillary-driven infiltration of the molten paraffin. The maximum actuation strain of the corrugated CNT-paraffin films (∼0.02-0.2) is comparable to natural muscle, yet the maximum stress is limited to ∼10 kPa by collapse of the CNT network. We also show how a CNT-paraffin film can serve as a self-activating thermal interface that closes a gap when it is heated. These new CNT-paraffin film actuators could be produced by large-area CNT growth, infiltration, and lamination methods, and are attractive for use in miniature systems due to their self-contained design.

Numerical simulation of axisymmetric valve operation for different outer cone angle

Science.gov (United States)

Smyk, Emil

One of the method of flow separation control is application of axisymmetric valve. It is composed of nozzle with core. Normally the main flow is attached to inner cone and flow by preferential collector to primary flow pipe. If through control nozzle starts flow jet (control jet) the main flow is switched to annular secondary collector. In both situation the main flow is deflected to inner or outer cone (placed at the outlet of the valve's nozzle) by Coanda effect. The paper deals with the numerical simulation of this axisymetric annular nozzle with integrated synthetic jet actuator. The aim of the work is influence examination of outer cone angle on deflection on main stream.

Turbulence downstream of subcoronary stentless and stented aortic valves.

Science.gov (United States)

Funder, Jonas Amstrup; Frost, Markus Winther; Wierup, Per; Klaaborg, Kaj-Erik; Hjortdal, Vibeke; Nygaard, Hans; Hasenkam, J Michael

2011-08-11

Regions of turbulence downstream of bioprosthetic heart valves may cause damage to blood components, vessel wall as well as to aortic valve leaflets. Stentless aortic heart valves are known to posses several hemodynamic benefits such as larger effective orifice areas, lower aortic transvalvular pressure difference and faster left ventricular mass regression compared with their stented counterpart. Whether this is reflected by diminished turbulence formation, remains to be shown. We implanted either stented pericardial valve prostheses (Mitroflow), stentless valve prostheses (Solo or Toronto SPV) in pigs or they preserved their native valves. Following surgery, blood velocity was measured in the cross sectional area downstream of the valves using 10MHz ultrasonic probes connected to a dedicated pulsed Doppler equipment. As a measure of turbulence, Reynolds normal stress (RNS) was calculated at two different blood pressures (baseline and 50% increase). We found no difference in maximum RNS measurements between any of the investigated valve groups. The native valve had significantly lower mean RNS values than the Mitroflow (p=0.004), Toronto SPV (p=0.008) and Solo valve (p=0.02). There were no statistically significant differences between the artificial valve groups (p=0.3). The mean RNS was significantly larger when increasing blood pressure (p=0.0006). We, thus, found no advantages for the stentless aortic valves compared with stented prosthesis in terms of lower maximum or mean RNS values. Native valves have a significantly lower mean RNS value than all investigated bioprostheses. Copyright © 2011 Elsevier Ltd. All rights reserved.

Analysis of aortic root surgery with composite mechanical aortic valve conduit and valve-sparing reconstruction.

Science.gov (United States)

Dias, Ricardo Ribeiro; Mejia, Omar Asdrubal Vilca; Fiorelli, Alfredo Inácio; Pomerantzeff, Pablo Maria Alberto; Dias, Altamiro Ribeiro; Mady, Charles; Stolf, Noedir Antonio Groppo

2010-01-01

Comparative analysis of early and late results of aortic root reconstruction with aortic valve sparing operations and the composite mechanical valve conduit replacement. From November 2002 to September 2009, 164 consecutive patients with mean age 54 ± 15 years, 115 male, underwent the aortic root reconstruction (125 mechanical valve conduit replacements and 39 valve sparing operations). Sixteen percent of patients had Marfan syndrome and 4.3% had bicuspid aortic valve. One hundred and forty-four patients (88%) were followed for a mean period of 41.1 ± 20.8 months. The hospital mortality was 4.9%, 5.6% in operations with valved conduits and 2.6% in the valve sparing procedures (P valve sparing operations, respectively (95% CI = 70% - 95%, P = 0.001), (95% CI = 82% - 95% P = 0.03) and (95% CI = 81% - 95%, P = 0.03). Multivariate analysis showed that creatinine greater than 1.4 mg/dl, Cabrol operation and renal dialysis were predictors of mortality, respectively, with occurrence chance of 6 (95% CI = 1.8 - 19.5, P = 0.003), 12 (95% CI = 3 - 49.7, P = 0.0004) and 16 (95% CI = 3.6 - 71.3, P = 0.0002). The aortic root reconstruction has a low early and late mortality, high survival free of complications and low need for reoperation. During the late follow-up, valve sparing aortic root reconstructions presented fewer incidences of bleeding, thromboembolic events and endocarditis.

A low-power-consumption out-of-Plane electrothermal actuator

OpenAIRE

Girbau Sala, David; Llamas Morote, Marco Antonio; Casals Terré, Jasmina; Simó Selvas, Francisco Javier; Pradell i Cara, Lluís; Lázaro Guillén, Antoni

2007-01-01

This paper proposes a new vertical electrothermal actuator. It can be considered as a hybrid between the traditional in-plane buckle-beam actuator and the vertical hot-cold actuator. It is here referred to as vertical buckle beam. At identical dimensional and bias conditions, it features a displacement larger than that of other vertical electrothermal actuators proposed so far in the literature. The actuator performance is demonstrated by means of an analytical model along with finite-element...

Levitating Micro-Actuators: A Review

Directory of Open Access Journals (Sweden)

Kirill V. Poletkin

2018-04-01

Full Text Available Through remote forces, levitating micro-actuators completely eliminate mechanical attachment between the stationary and moving parts of a micro-actuator, thus providing a fundamental solution to overcoming the domination of friction over inertial forces at the micro-scale. Eliminating the usual mechanical constraints promises micro-actuators with increased operational capabilities and low dissipation energy. Further reduction of friction and hence dissipation by means of vacuum leads to dramatic increases of performance when compared to mechanically tethered counterparts. In order to efficiently employ the benefits provided by levitation, micro-actuators are classified according to their physical principles as well as by their combinations. Different operating principles, structures, materials and fabrication methods are considered. A detailed analysis of the significant achievements in the technology of micro-optics, micro-magnets and micro-coil fabrication, along with the development of new magnetic materials during recent decades, which has driven the creation of new application domains for levitating micro-actuators is performed.

Development of a system for monitoring and diagnosis using Fuzzy logic in control valves of laboratory test equipment of Experimental Center Aramar

International Nuclear Information System (INIS)

Porto Junior, Almir Carlos Soares

2014-01-01

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

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

Science.gov (United States)

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

2017-11-01

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

Experimental Investigation on Airfoil Shock Control by Plasma Aerodynamic Actuation

International Nuclear Information System (INIS)

Sun Quan; Cheng Bangqin; Li Yinghong; Cui Wei; Jin Di; Li Jun

2013-01-01

An experimental investigation on airfoil (NACA64—215) shock control is performed by plasma aerodynamic actuation in a supersonic tunnel (Ma = 2). The results of schlieren and pressure measurement show that when plasma aerodynamic actuation is applied, the position moves forward and the intensity of shock at the head of the airfoil weakens. With the increase in actuating voltage, the total pressure measured at the head of the airfoil increases, which means that the shock intensity decreases and the control effect increases. The best actuation effect is caused by upwind-direction actuation with a magnetic field, and then downwind-direction actuation with a magnetic field, while the control effect of aerodynamic actuation without a magnetic field is the most inconspicuous. The mean intensity of the normal shock at the head of the airfoil is relatively decreased by 16.33%, and the normal shock intensity is relatively reduced by 27.5% when 1000 V actuating voltage and upwind-direction actuation are applied with a magnetic field. This paper theoretically analyzes the Joule heating effect generated by DC discharge and the Lorentz force effect caused by the magnetic field. The discharge characteristics are compared for all kinds of actuation conditions to reveal the mechanism of shock control by plasma aerodynamic actuation

Regulatory standpoints on the design-basis capability of safety-related motor-operated valves(MOVs) and power-operated gate valves(POGVs)

International Nuclear Information System (INIS)

Kim, W. T.; Kum, O. H.

1999-01-01

The weakness in the design-basis capability of Motor-Operated Valves(MOVs) and the susceptibility to Pressure Locking and Thermal Binding phenomena of Power-Operated Gate Valves(POGVs) have been major concerns to be resolved in the nuclear society in and abroad since Three Mile Island accident occurred in the USA in 1979. Through detailed analysis of operating experience and regulatory activities, some MOVs and POGVs have been found to be unreliable in performing their safety functions when they are required to do so under certain conditions, especially under design-basis accident conditions. Further, it is well understood that these safety problems may not be identified by the typical valve in-service testing(IST). USNRC has published three Generic Letters, GL 89-10, GL 95-07, and GL 96-05, requiring nuclear plant licensees to take appropriate actions to resolve the problems mentioned above. Korean nuclear regulatory body has made public an administration measure called 'Regulatory recommendation to verify safety functions of the safety-related MOVs and POGVs' on June 13, 1997, and in this administration measure Korean utility is asked to submit written documents to show how it assure design-basis capability of these valves. The following are among the major concerns being considered from a regulation standpoint. Program scope and implementation priority, dynamic tests under differential pressure conditions, accuracy of diagnostic equipment, torque switch setting and torque bypass percentage, weak link analysis, motor actuator sizing, corrective actions taken to resolve pressure locking and thermal binding susceptibility, and a periodic verification program for the valves once design-basis capability has been verified

Bypass valve and coolant flow controls for optimum temperatures in waste heat recovery systems

Science.gov (United States)

Meisner, Gregory P

2013-10-08

Implementing an optimized waste heat recovery system includes calculating a temperature and a rate of change in temperature of a heat exchanger of a waste heat recovery system, and predicting a temperature and a rate of change in temperature of a material flowing through a channel of the waste heat recovery system. Upon determining the rate of change in the temperature of the material is predicted to be higher than the rate of change in the temperature of the heat exchanger, the optimized waste heat recovery system calculates a valve position and timing for the channel that is configurable for achieving a rate of material flow that is determined to produce and maintain a defined threshold temperature of the heat exchanger, and actuates the valve according to the calculated valve position and calculated timing.

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

International Nuclear Information System (INIS)

Chabat-Courrede, Jean.

1981-01-01

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

Fast-Valving of Large Steam Turbine Units as a Means of Power System Security Enhancement

Directory of Open Access Journals (Sweden)

Bogdan Sobczak

2014-03-01

Full Text Available Fast-valving assists in maintaining system stability following a severe transmission system fault by reducing the turbine mechanical power. Fast-valving consists in rapid closing and opening of steam valves in an adequate manner to reduce the generator accelerating power following the recognition of a severe fault. FV can be an effective and economical method of meeting the performance requirements of a power system in the presence of an increase in wind and solar generation in the power system, newly connected large thermal units and delaying of building new transmission lines. The principle of fast-valving and advantages of applying this technique in large steam turbine units was presented in the paper. Effectiveness of fast-valving in enhancing the stability of the Polish Power Grid was analyzed. The feasibility study of fast-valving application in the 560 MW unit in Kozienice Power Station (EW SA was discussed.

A Solar Energy Powered Autonomous Wireless Actuator Node for Irrigation Systems

Directory of Open Access Journals (Sweden)

Rafael Lajara

2010-12-01

Full Text Available The design of a fully autonomous and wireless actuator node (“wEcoValve mote” based on the IEEE 802.15.4 standard is presented. The system allows remote control (open/close of a 3-lead magnetic latch solenoid, commonly used in drip irrigation systems in applications such as agricultural areas, greenhouses, gardens, etc. The very low power consumption of the system in conjunction with the low power consumption of the valve, only when switching positions, allows the system to be solar powered, thus eliminating the need of wires and facilitating its deployment. By using supercapacitors recharged from a specifically designed solar power module, the need to replace batteries is also eliminated and the system is completely autonomous and maintenance free. The “wEcoValve mote” firmware is based on a synchronous protocol that allows a bidirectional communication with a latency optimized for real-time work, with a synchronization time between nodes of 4 s, thus achieving a power consumption average of 2.9 mW.

Double-disc gate valve

International Nuclear Information System (INIS)

Wheatley, S.J.

1979-01-01

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

Performance of Cableless Magnetic In-Piping Actuator Capable of High-Speed Movement by Means of Inertial Force

Directory of Open Access Journals (Sweden)

Hiroyuki Yaguchi

2011-01-01

Full Text Available The present paper proposes a novel cableless magnetic actuator with a new propulsion module that exhibits a very high thrusting force. This actuator contains an electrical inverter that directly transforms DC from button batteries into AC. The electrical DC-AC inverter incorporates a mass-spring system, a reed switch, and a curved permanent magnet that switches under an electromagnetic force. The actuator is moved by the inertial force of the mass-spring system due to mechanical resonance energy. The experimental results show that the actuator is able to move upward at a speed of 19.7 mm/s when using 10 button batteries when pulling a 20 g load mass. This cableless magnetic actuator has several possible applications, including narrow pipe inspection and maintenance.

Bentall Procedure Using Cryopreserved Valved Aortic Homografts

Science.gov (United States)

Christenson, Jan T.; Sierra, Jorge; Trindade, Pedro T.; Didier, Dominique; Kalangos, Afksendiyos

2004-01-01

The Bentall procedure is the standard operation for patients who have lesions of the ascending aorta associated with aortic valve disease. In many cases, however, mechanical prosthetic conduits are not suitable. There are few reports in the English-language medical literature concerning the mid- to long-term outcome of Bentall operations with cryopreserved homografts. Therefore, we reviewed our experience with this procedure and valved homografts. From January 1997 through December 2002, 21 patients underwent a Bentall operation with cryopreserved homografts at our institution. There were 14 males and 7 females; the mean age was 36 ± 21 years (range, 15–74 years). Eleven patients had undergone previous aortic valve surgery. All patients had aortic dilatation or aneurysms involving the ascending aorta. Indications for surgery included aortic valve stenosis or insufficiency, and aortic valve endocarditis (native valve or prosthetic). One patient had Takayasu's arteritis and 3 had Marfan syndrome. There was 1 hospital death (due to sepsis), but no other major postoperative complications. The mean hospital stay was 14 ± 7 days. Follow-up echocardiographic and computed tomographic scans were performed yearly. The mean follow-up was 34 months (6–72 months). Follow-up imaging revealed no calcifications or degenerative processes related to the homograft. Four patients had minimal valve regurgitation. Two patients died during follow-up. The 3-year actuarial survival rate was 85.7%. Our data suggest that the Bentall procedure with a valved homograft conduit is a safe procedure with excellent mid- to long-term results, comparable to results reported with aortic valve replacement with a homograft. PMID:15745290

MANAGEMENT OF FAILED MITRAL VALVE REPLACEMENT. THE DURBAN EXPERIENCE.

Science.gov (United States)

Kistan, D; Booysen, M; Alexander, G; Madiba, T E

2017-06-01

Mitral valve replacement is the procedure of choice in patients with severe mitral valve disease. However, these patients are surviving longer and are thus at an increased risk of prosthesis failure or valve-related complications. Study setting: Inkosi Albert Luthuli Central Hospital, a tertiary referral Hospital in Durban. Study population: All patients undergoing redo mechanical mitral valve replacement surgery between January 2005 and December 2014. Study design: Retrospective analysis of patients undergoing redo mitral valve replacement. Patients were identified from theatre record books, their files were electronically accessed and pertinent information extracted onto a data capture sheet. Information documented included demographics, duration to failure, INR, Albumin, HIV status, clinical findings and outcome. The data was stored on an Excel datasheet. Fifty-eight patients were documented (mean age 32 ± 15.81 years; M:F 1:3). Ten patients (17%) were HIV positive (median CD4 count 478). Mean duration between first surgery and redo was 8.8 years. Thirty-five patients (60%) had no co-morbidities. Presenting features at redo surgery were congestive cardiac failure (27), chest pain (11) and palpitations (17). Mean preoperative Ejection Fraction was 51.65 %. Twenty-nine patients (55%) had emergency redo surgery. Twenty-two patients (75%) had acute prosthetic valve thrombosis. Thirty-two patients had tricuspid regurgitation. Original pathology was documented in 23 patients (40%) as Rheumatic valve disease. Prosthetic valve thrombosis was documented in 31 patients (54%). The most commonly used valve was the On-X. Mean presenting INR was 1.96 + 1.2 and mean presenting serum albumin was 36.7 + 7.8 g/l. Forty-one patients (71%) were found to be compliant to Warfarin therapy prior to redo surgery. Mean ICU stay was 6 +9 days. Two patients died postoperatively. Mean followup was 32 + 26.6 months. Twelve patients (20.7%) developed postoperative complications. Patients

Control of spool position of on/off solenoid operated hydraulic valve by sliding-mode controller

Energy Technology Data Exchange (ETDEWEB)

Lee, Jae Hak; Hong, Hyun Wook; Park, Myeong Kwan [Pusan National University, Busan (Korea, Republic of); Yun, Young Won [KHPS, Busan (Korea, Republic of)

2015-11-15

The use of on/off solenoid operated hydraulic valves instead of proportional valves has been attracting the interest of many researchers and engineers. However, there exist difficulties in controlling the on/off valve because of highly nonlinear characteristics including hysteresis and saturation. This paper considers the application of on/off solenoid operated hydraulic valves to control position of a hydraulic cylinder with the aim of evaluating, feasibility and practicability of their implementation and understanding the potential benefits when they are used in existing hydraulic systems. Assuming that only the current is measured, a sliding mode observer is designed to estimate the spool position and velocity. To alleviate the aforementioned difficulties in controlling the spool position, a nonlinear observer-based controller of an on/off solenoid valve is designed, taking into account the estimated values, based on a nonlinear model including hysteresis and saturation. The control objective is to track a desired spool trajectory. Simulation and experimental results illustrate the efficiency of the designed controller. The proposed controller is validated again in a single-rod hydraulic actuator. Experimental results show that the fluid flow through the valve orifice by controlling the spool position was successfully controlled.

FAILURE MODE AND EFFECT ANALYSIS (FMEA OF BUTTERFLY VALVE IN OIL AND GAS INDUSTRY

Directory of Open Access Journals (Sweden)

MUHAMMAD AMIRUL BIN YUSOF

2016-04-01

Full Text Available Butterfly valves are mostly used in various industries such as oil and gas plant. This valve operates with rotating motion using pneumatic system. Rotating actuator turns the disc either parallel or perpendicular to the flow. When the valve is fully open, the disc is rotated a quarter turn so that it allows free passage of the fluid and when fully closed, the disc rotated a quarter turns to block the fluid. The primary failure modes for valves are the valve leaks to environment through flanges, seals on the valve body, valve stem packing not properly protected, over tightened packing nuts, the valve cracks and leaks over the seat. To identify the failure of valve Failure Mode and Effects Analysis has been chosen. FMEA is the one of technique to perform failure analysis. It involves reviewing as many components to identify failure modes, and their causes and effects. For each component, the failure modes and their resulting effects on the rest of the system are recorded in a specific FMEA form. Risk priority number, severity, detection, occurrence are the factor determined in this studies. Risk priority number helps to find out the highest hazardous activities which need more attention than the other activity. The highest score of risk priority number in this research is seat. Action plan was proposed to reduce the risk priority number and so that potential failures also will be reduced.

Design optimization of a novel pMDI actuator for systemic drug delivery.

Science.gov (United States)

Kakade, Prashant P; Versteeg, Henk K; Hargrave, Graham K; Genova, Perry; Williams Iii, Robert C; Deaton, Daniel

2007-01-01

Pressurized metered dose inhalers (pMDIs) are the most widely prescribed and economical respiratory drug delivery systems. Conventional pMDI actuators-those based on "two-orifice-and-sump" designs-produce an aerosol with a reasonable respirable fraction, but with high aerosol velocity. The latter is responsible for high oropharyngeal deposition, and consequently low drug delivery efficiency. Kos' pMDI technology is based on a proprietary vortex nozzle actuator (VNA), an innovative actuator configuration that seeks to reduce aerosol plume velocity, thereby promoting deep lung deposition. Using VNA development as a case study, this paper presents a systematic design optimization process to improve the actuator performance through use of advanced optical characterization tools. The optimization effort mainly relied on laser-based optical diagnostics to provide an improved understanding of the fundamentals of aerosol formation and interplay of various geometrical factors. The performance of the optimized VNA design thus evolved was characterized using phase Doppler anemometry and cascade impaction. The aerosol velocities for both standard and optimized VNA designs were found to be comparable, with both notably less than conventional actuators. The optimized VNA design also significantly reduces drug deposition in the actuator as well as USP throat adapter, which in turn, leads to a significantly higher fine particle fraction than the standard design (78 +/- 3% vs. 63 +/- 2% on an ex valve basis). This improved drug delivery efficiency makes VNA technology a practical proposition as a systemic drug delivery platform. Thus, this paper demonstrates how advanced optical diagnostic and characterization tools can be used in the development of high efficiency aerosol drug delivery devices.

Stent valve implantation in conventional redo aortic valve surgery to prevent patient-prosthesis mismatch.

Science.gov (United States)

Ferrari, Enrico; Franciosi, Giorgio; Clivio, Sara; Faletra, Francesco; Moccetti, Marco; Moccetti, Tiziano; Pedrazzini, Giovanni; Demertzis, Stefanos

2017-03-01

The goal was to show the technical details, feasibility and clinical results of balloon-expandable stent valve implantation in the aortic position during conventional redo open-heart surgery in selected obese patients with a small aortic prosthesis and severe patient-prosthesis mismatch. Two symptomatic overweight patients (body mass index of 31 and 38), each with a small aortic prosthesis (a 4-year-old, 21-mm Hancock II biological valve and a 29-year-old, 23-mm Duromedic mechanical valve), increased transvalvular gradients (59/31 and 74/44 mmHg) and a reduced indexed effective orifice area (0.50 and 0.43 cm 2 /m 2 ) underwent implantation of two 26-mm balloon-expandable Sapien 3 valves during standard on-pump redo valve surgery. Using full re-sternotomy, cardiopulmonary bypass and cardioplegic arrest, the two balloon-expandable stent valves were implanted under direct view using a standard aortotomy, after prosthesis removal and without annulus enlargement. Aortic cross-clamp times were 162 and 126 min; cardiopulmonary bypass times were 178 and 180 min; total surgical times were 360 and 318 min. At discharge, echocardiograms showed transvalvular peak and mean gradients of 13/9 and 23/13 mmHg and indexed effective orifice areas of 0.64 and 1.08 cm 2 /m 2 . The 3-month echocardiographic follow-up showed transvalvular peak and mean gradients of 18/9 and 19/11 mmHg and indexed effective orifice areas of 0.78 cm 2 /m 2 and 0.84 cm 2 /m 2 , with improved symptoms (New York Heart Association class 1). Implantation of a balloon-expandable stent valve during redo aortic valve surgery is feasible in selected cases and prevents patient-prosthesis mismatch in obese patients without need for aortic annulus enlargement. Moreover, in the case of stent valve degeneration, this approach permits additional valve-in-valve procedures with large stent valves and prevents re-redo surgery. © The Author 2016. Published by Oxford University Press on behalf of the

Improvements in valve reliability due to implementation of effective condition monitoring programs

International Nuclear Information System (INIS)

Hale, Stan

2003-01-01

Modern diagnostic systems for motor-operated valves, pneumatic control valves and checkvalves have facilitated a shift in the maintenance philosophy for valves and actuators in nuclear power plants from schedule based to condition-based maintenance (CBM). This shift enables plant management to focus resources and schedule priority on the plant equipment that warrants attention thereby not wasting resources or increasing the human factors risk on equipment that has not degraded. The most recent initiatives combine condition monitoring with risk/safety insights to focus attention and resonances on the right equipment at the right time consistent with each component's safety-significance. The activities of the ASME working groups responsible for nuclear O and M codes have kept pace with the technology and process improvements necessary to maximize the technical and economic benefits of condition based and risk informed maintenance. This paper discusses adoption of valve condition monitoring in the nuclear power industry, changes to ASME codes and standards during the 90's to facilitate adoption of condition monitoring technology for in-service testing and recent efforts to combine risk insights with condition monitoring strategies to achieve the highest level of valve reliability and nuclear safety without over inflating maintenance cost. (author)

Modelling of coupled self-actuating safety, relief and damped check valve systems with the codes TRAC-PF1 and ROLAST

International Nuclear Information System (INIS)

Neumann, U.; Puzalowski, R.; Grimm, I.

1985-01-01

Numerical valve models for simulation of selfactuating safety valves and damped check valves are introduced for the computer programs TRAC-PF1 and ROLAST. As examples of application post-test calculations and stability analysis are given. (orig.)

Solenoid Driven Pressure Valve System: Toward Versatile Fluidic Control in Paper Microfluidics.

Science.gov (United States)

Kim, Taehoon H; Hahn, Young Ki; Lee, Jungmin; van Noort, Danny; Kim, Minseok S

2018-02-20

As paper-based diagnostics has become predominantly driven by more advanced microfluidic technology, many of the research efforts are still focused on developing reliable and versatile fluidic control devices, apart from improving sensitivity and reproducibility. In this work, we introduce a novel and robust paper fluidic control system enabling versatile fluidic control. The system comprises a linear push-pull solenoid and an Arduino Uno microcontroller. The precisely controlled pressure exerted on the paper stops the flow. We first determined the stroke distance of the solenoid to obtain a constant pressure while examining the fluidic time delay as a function of the pressure. Results showed that strips of grade 1 chromatography paper had superior reproducibility in fluid transport. Next, we characterized the reproducibility of the fluidic velocity which depends on the type and grade of paper used. As such, we were able to control the flow velocity on the paper and also achieve a complete stop of flow with a pressure over 2.0 MPa. Notably, after the actuation of the pressure driven valve (PDV), the previously pressed area regained its original flow properties. This means that, even on a previously pressed area, multiple valve operations can be successfully conducted. To the best of our knowledge, this is the first demonstration of an active and repetitive valve operation in paper microfluidics. As a proof of concept, we have chosen to perform a multistep detection system in the form of an enzyme-linked immunosorbent assay with mouse IgG as the target analyte.

Method for driving an actuator, actuator drive, and apparatus comprising an actuator

OpenAIRE

2010-01-01

An actuator driver circuit includes a drive signal source and an electrical damping element having a negative resistance connected in series with the drive signal source. A controllable switch is provided for selectively switching the electrical damping element into or put of a signal path from a drive signal source output to a driver circuit output, in order to selectively change the electrical damping of an actuator. For example, the electrical damping of a radial actuator or a focus actuat...

Design and characterization of poly(dimethylsiloxane)-based valves for interfacing continuous-flow sampling to microchip electrophoresis.

Science.gov (United States)

Li, Michelle W; Huynh, Bryan H; Hulvey, Matthew K; Lunte, Susan M; Martin, R Scott

2006-02-15

This work describes the fabrication and evaluation of a poly(dimethyl)siloxane (PDMS)-based device that enables the discrete injection of a sample plug from a continuous-flow stream into a microchannel for subsequent analysis by electrophoresis. Devices were fabricated by aligning valving and flow channel layers followed by plasma sealing the combined layers onto a glass plate that contained fittings for the introduction of liquid sample and nitrogen gas. The design incorporates a reduced-volume pneumatic valve that actuates (on the order of hundreds of milliseconds) to allow analyte from a continuously flowing sampling channel to be injected into a separation channel for electrophoresis. The injector design was optimized to include a pushback channel to flush away stagnant sample associated with the injector dead volume. The effect of the valve actuation time, the pushback voltage, and the sampling stream flow rate on the performance of the device was characterized. Using the optimized design and an injection frequency of 0.64 Hz showed that the injection process is reproducible (RSD of 1.77%, n = 15). Concentration change experiments using fluorescein as the analyte showed that the device could achieve a lag time as small as 14 s. Finally, to demonstrate the potential uses of this device, the microchip was coupled to a microdialysis probe to monitor a concentration change and sample a fluorescein dye mixture.

Additively Manufactured Main Fuel Valve Housing

Science.gov (United States)

Eddleman, David; Richard, Jim

2015-01-01

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

[Ministernotomy: a preliminary experience in heart valve surgery].

Science.gov (United States)

Kovarević, Pavle; Mihajlović, Bogoljub; Velicki, Lazar; Redzek, Aleksandar; Ivanović, Vladimir; Komazec, Nikola

2011-05-01

The last decade of the 20th century brought up a significant development in the field of minimally invasive approaches to the valvular heart surgery. Potential benefits of this method are: good esthetic appearance, reduced pain, reduction of postoperative hemorrhage and incidence of surgical site infection, shorter postoperative intensive care units (ICU) period and overall in-hospital period. Partial upper median stemotomy currently presents as a state-of-the art method for minimally invasive surgery of cardiac valves. The aim of this study was to report on initial experience in application of this surgical method in the surgery of mitral and aortic valves. The study was designed and conducted in a prospective manner and included all the patients who underwent minimally invasive cardiac valve surgery through the partial upper median stemotomy during the period November 2008 - August 2009. We analyzed the data on mean age of patients, mean extubation time, mean postoperative drainage, mean duration of hospital stay, as well as on occurance of postoperative complications (postoperative bleeding, surgical site infection and cerebrovascular insult). During the observed period, in the Institute for Cardiovascular Diseases of Vojvodina, Clinic for Cardiovascular Surgery, 17 ministernotomies were performed, with 14 aortic valve replacements (82.35%) and 3 mitral valve replacements (17.65%). Mean age of the patients was 60.78 +/- 12.99 years (64.71% males, 35.29% females). Mean extubation time was 12.53 +/- 8.87 hours with 23.5% of the patients extubated in less than 8 hours. Mean duration of hospital stay was 12.35 +/- 10.17 days (in 29.4% of the patients less than 8 days). Mean postoperative drainage was 547.06 +/- 335.2 mL. Postoperative complications included: bleeding (5.88%) and cerebrovascular insult (5.88%). One patient (5.88%) required conversion to full stemotomy. Partial upper median sternotomy represents the optimal surgical method for the interventions on the

The static actuation of dielectric elastomer actuators: how does pre-stretch improve actuation?

International Nuclear Information System (INIS)

Kofod, Guggi

2008-01-01

It has previously been shown that providing dielectric elastomer actuators with a level of pre-stretch can improve properties such as breakdown strength, actuation strain and efficiency. The actuation in such actuators depends on an interplay between the highly nonlinear hyperelastic stress-strain behaviour with the electrostatic Maxwell's stress; however, the direct effects of pre-stretch on the electromechanical coupling have still not been investigated in detail. We compare several experimental results found in the literature on the hyperelastic parameters of the Ogden model for the commonly used material VHB 4910, and introduce a more detailed and thus more accurate fit to a previous uniaxial stress-strain experiment. Electrostatic actuation models for a pure shear cuboid dielectric elastomer actuator with pre-stretch are introduced, for both intensive and extensive variables. For both intensive and extensive variables the constant strain (blocked stress or force) as well as the actuation strain is presented. It is shown how in the particular case of isotropic amorphous elastomers the pre-stretch does not affect the electromechanical coupling directly, and that the enhancement in actuation strain due to pre-stretch occurs through the alteration of the geometrical dimensions of the actuator. Also, the presence of the optimum load is explained as being due to the plateau region in the force-stretch curve, and it is shown that pre-stretch is not able to affect its position. Finally, it is shown how the simplified Ogden fit leads to entirely different conclusions for actuation strain in terms of extensive variables as does the detailed fit, emphasizing the importance of employing accurate hyperelastic models for the stress-stretch behaviour of the elastomer.

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

Science.gov (United States)

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

2015-01-01

It is advantageous for gas-fed pulsed electric thrusters to employ pulsed valves so propellant is only flowing to the device during operation. The propellant utilization of the thruster will be maximized when all the gas injected into the thruster is acted upon by the fields produced by the electrical pulse. Gas that is injected too early will diffuse away from the thruster before the electrical pulse can act to accelerate the propellant. Gas that is injected too late will miss being accelerated by the already-completed electrical pulse. As a consequence, the valve must open quickly and close equally quickly, only remaining open for a short duration. In addition, the valve must have only a small amount of volume between the sealing body and the thruster so the front and back ends of the pulse are as coincident as possible with the valve cycling, with very little latent propellant remaining in the feed lines after the valve is closed. For a real mission of interest, a pulsed thruster can be expected to pulse at least 10(exp 10) - 10(exp 11) times, setting the range for the number of times a valve must open and close. The valves described in this paper have been fabricated and tested for operation in an inductive pulsed plasma thruster (IPPT) for in-space propulsion. In general, an IPPT is an electrodeless space propulsion device where a capacitor is charged to an initial voltage and then discharged, producing a high-current pulse through a coil. The field produced by this pulse ionizes propellant, inductively driving current in a plasma located near the face of the coil. Once the plasma is formed, it can be accelerated and expelled at a high exhaust velocity by the electromagnetic Lorentz body force arising from the interaction of the induced plasma current and the magnetic field produced by the current in the coil. The valve characteristics needed for the IPPT application require a fast-acting valve capable of a minimum of 10(exp 10) valve actuation cycles. Since

A Method for Aileron Actuator Fault Diagnosis Based on PCA and PGC-SVM

Directory of Open Access Journals (Sweden)

Wei-Li Qin

2016-01-01

Full Text Available Aileron actuators are pivotal components for aircraft flight control system. Thus, the fault diagnosis of aileron actuators is vital in the enhancement of the reliability and fault tolerant capability. This paper presents an aileron actuator fault diagnosis approach combining principal component analysis (PCA, grid search (GS, 10-fold cross validation (CV, and one-versus-one support vector machine (SVM. This method is referred to as PGC-SVM and utilizes the direct drive valve input, force motor current, and displacement feedback signal to realize fault detection and location. First, several common faults of aileron actuators, which include force motor coil break, sensor coil break, cylinder leakage, and amplifier gain reduction, are extracted from the fault quadrantal diagram; the corresponding fault mechanisms are analyzed. Second, the data feature extraction is performed with dimension reduction using PCA. Finally, the GS and CV algorithms are employed to train a one-versus-one SVM for fault classification, thus obtaining the optimal model parameters and assuring the generalization of the trained SVM, respectively. To verify the effectiveness of the proposed approach, four types of faults are introduced into the simulation model established by AMESim and Simulink. The results demonstrate its desirable diagnostic performance which outperforms that of the traditional SVM by comparison.

Chained Iron Microparticles for Directionally Controlled Actuation of Soft Robots.

Science.gov (United States)

Schmauch, Marissa M; Mishra, Sumeet R; Evans, Benjamin A; Velev, Orlin D; Tracy, Joseph B

2017-04-05

Magnetic field-directed self-assembly of magnetic particles in chains is useful for developing directionally responsive materials for applications in soft robotics. Using materials with greater complexity allows advanced functions, while still using simple device architectures. Elastomer films containing chained magnetic microparticles were prepared through solvent casting and formed into magnetically actuated lifters, accordions, valves, and pumps. Chaining both enhances actuation and imparts a directional response. Cantilevers used as lifters were able to lift up to 50 times the mass of the polymer film. We introduce the "specific torque", the torque per field per mass of magnetic particles, as a figure of merit for assessing and comparing the performance of lifters and related devices. Devices in this work generated specific torques of 68 Nm/kgT, which is significantly higher than in previously reported actuators. Applying magnetic fields to folded accordion structures caused extension and compression, depending on the accordion's orientation. In peristaltic pumps comprised of composite tubes containing embedded chains, magnetic fields caused a section of the tube to pinch closed where the field was applied. These results will facilitate both the further development of soft robots based on chained magnetic particles and efforts to engineer materials with higher specific torque.

Analysis of the Impact of Early Exhaust Valve Opening and Cylinder Deactivation on Aftertreatment Thermal Management and Efficiency for Compression Ignition Engines

OpenAIRE

Roberts, Leighton Edward

2014-01-01

In order to meet strict emissions regulations, engine manufacturers have implemented aftertreatment technologies which reduce the tailpipe emissions from diesel engines. The effectiveness of most of these systems is limited when exhaust temperatures are low (usually below 200°C to 250°C). This is a problem for extended low load operation, such as idling and during cold start. Use of variable valve actuation, including early exhaust valve opening (EEVO) and cylinder deactivation (CDA), has bee...

Activation of Actuating Hydrogels with WS2 Nanosheets for Biomimetic Cellular Structures and Steerable Prompt Deformation.

Science.gov (United States)

Zong, Lu; Li, Xiankai; Han, Xiangsheng; Lv, Lili; Li, Mingjie; You, Jun; Wu, Xiaochen; Li, Chaoxu

2017-09-20

Macroscopic soft actuation is intrinsic to living organisms in nature, including slow deformation (e.g., contraction, bending, twisting, and curling) of plants motivated by microscopic swelling and shrinking of cells, and rapid motion of animals (e.g., deformation of jellyfish) motivated by cooperative nanoscale movement of motor proteins. These actuation behaviors, with an exceptional combination of tunable speed and programmable deformation direction, inspire us to design artificial soft actuators for broad applications in artificial muscles, nanofabrication, chemical valves, microlenses, soft robotics, etc. However, so far artificial soft actuators have been typically produced on the basis of poly(N-isopropylacrylamide) (PNiPAM), whose deformation is motived by volumetric shrinkage and swelling in analogue to plant cells, and exhibits sluggish actuation kinetics. In this study, alginate-exfoliated WS 2 nanosheets were incorporated into ice-template-polymerized PNiPAM hydrogels with the cellular microstructures which mimic plant cells, yet the prompt steerable actuation of animals. Because of the nanosheet-reinforced pore walls formed in situ in freezing polymerization and reasonable hierarchical water channels, this cellular hybrid hydrogel achieves super deformation speed (on the order of magnitude of 10° s), controllable deformation direction, and high near-infrared light responsiveness, offering an unprecedented platform of artificial muscles for various soft robotics and devices (e.g., rotator, microvalve, aquatic swimmer, and water-lifting filter).

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Minimally invasive aortic valve replacement

DEFF Research Database (Denmark)

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

2009-01-01

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

Fast-Valving of Large Steam Turbine Units as a Means of Power System Security Enhancement

OpenAIRE

Bogdan Sobczak; Robert Rink; Rafał Kuczyński; Robert Trębski

2014-01-01

Fast-valving assists in maintaining system stability following a severe transmission system fault by reducing the turbine mechanical power. Fast-valving consists in rapid closing and opening of steam valves in an adequate manner to reduce the generator accelerating power following the recognition of a severe fault. FV can be an effective and economical method of meeting the performance requirements of a power system in the presence of an increase in wind and solar generation in the power syst...

Design Comparison of Autonomous High Voltage Driving System for DEAP Actuator

DEFF Research Database (Denmark)

Huang, Lina; Pittini, Riccardo; Zhang, Zhe

2014-01-01

As a new type of smart material, the Dielectric Electro Active Polymer (DEAP) is introduced in terms of configuration, working principle and potential applications. The design of an autonomous high voltage driving system for DEAP actuator is investigated. The system configuration and the design...... methodology of a high voltage converter are discussed in detail. Based on the heating valve application, three different high voltage converter solutions have been proposed. The different proposals have been compared in terms of energy loss, volume and cost. Finally, the design selection suggestions...

Emergency scram actuation device for nuclear reactors

International Nuclear Information System (INIS)

Noyes, R.C.; Zaman, S.U.; Stuteville, D.W.

1979-01-01

The safety parameter employed for emergency scrams of a liquid metal cooled reactor is the coolant pressure. An actuation bellows is provided which is connected to a measuring chamber by means of a flow system. Both units are installed in a coolant flow section. The measuring chamber proper is connected with the coolant by means of an aperture limiting the flow. Inside the measuring chamber there is an expansion space filled with gas. Pressure changes in the coolant affect the pressure in the expansion space. Expansion of the bellows actuates the release mechanism. (DG) [de

Experimental investigation of the fluid dynamic efficiency of a high performance multi-valve internal combustion engine during the intake phase: Influence of valve-valve interference phenomena

Directory of Open Access Journals (Sweden)

Algieri Angelo

2013-01-01

Full Text Available The purpose of the present work is the analysis of the fluid dynamic behavior of a high performance internal combustion engine during the intake phase. In particular, a four-valve spark-ignition engine has been characterized at the steady flow rig. Dimensionless discharge coefficients have been used to define the global fluid dynamic efficiency of the intake system, while the Laser Doppler Anemometry (LDA technique has been employed to evaluate the mean flow in the valve curtain area and to characterise the interference phenomena between the two intake valves. The investigation has shown the significant influence of the valve lift on the volumetric efficiency of the intake apparatus. Moreover, the experimental analysis has highlighted that the valve-valve interference phenomena have a relevant impact on the head breathability, on the flow development within the combustion chamber and on the velocity standard deviations.

Mechanical Aortic Valve Replacement in Octogenarian

Directory of Open Access Journals (Sweden)

Irfan Tasoglu

2013-10-01

Full Text Available Aim: This study analyzes the long-term outcomes of mechanical aortic valve replacement in octogenarian patients. Material and Method: A retrospective review was performed on 23 octogenarian patients who underwent mechanical aortic valve replacement. Hospital mortality, postoperative intensive care unit stay, hospital stay and long-term results was examined. Estimates of the cumulative event mortality rate were calculated by the Kaplan-Meier method. Results: The mean age of all patients was 82.9±2.3 years and most were men (65.22%. The median ejection fraction was 45%. 73.91% of patients were in New York Heart Association class III-IV. Thirteen patients (56.52% in this study underwent combined procedure, the remaining 10 (43.48% patients underwent isolated aortic valve replacement. The most common valve size was 23 mm. The mean intensive care unit stay was 1.76±1.14 days. The mean hospital stay was 9.33±5.06 days. No complications were observed in 56.52% patients during their hospital stay. The overall hospital mortality was 8.7%. Follow-up was completed for all 23 patients. Median follow-up time was 33 months (1-108 months. Actuarial survival among discharged from hospital was 59% at 5 years. Discussion: Mechanical aortic valve replacement is a safe procedure in octogenarian patients and can be performed safely even in combined procedure.

Unicuspid aortic valve disease: a magnetic resonance imaging study

Energy Technology Data Exchange (ETDEWEB)

Debl, K.; Buchner, S.; Heinicke, N.; Riegger, G.; Luchner, A. [Klinik und Poliklinik fuer Innere Medizin II, Universitaetsklinikum Regensburg (Germany); Djavidani, B.; Poschenrieder, F.; Feuerbach, S. [Inst. fuer Roentgendiagnostik, Universitaetsklinikum Regensburg (Germany); Schmid, C.; Kobuch, R. [Klinik und Poliklinik fuer Herz-, Thorax- und herznahe Gefaesschirurgie, Universitaetsklinikum Regensburg (Germany)

2008-11-15

Purpose: congenitally malformed aortic valves are a common finding in adults with aortic valve disease. Most of these patients have bicuspid aortic valve disease. Unicuspid aortic valve disease (UAV) is rare. The aim of our study was to describe valve morphology and the dimensions of the proximal aorta in a cohort of 12 patients with UAV in comparison to tricuspid aortic valve disease (TAV) using magnetic resonance imaging (MRI). Materials and methods/results: MRI studies were performed on a 1.5 T scanner in a total of 288 consecutive patients with aortic valve disease. 12 aortic valves were retrospectively classified as UAV. Annulus areas and dimensions of the thoracic aorta were retrospectively compared to a cohort of 103 patients with TAV. In UAV, valve morphology was unicuspid unicommissural with a posterior commissure in all patients. Mean annulus areas and mean diameters of the ascending aorta were significantly greater in UAV compared to TAV (12.6 {+-} 4.7 cm{sup 2} vs. 8.7 {+-} 2.3 cm{sup 2}, p < 0.01 and 4.6 {+-} 0.7 cm vs. 3.6 {+-} 0.5 cm, p < 0.0001, respectively), while no differences were observed in the mean diameters of the aortic arch (2.3 {+-} 0.6 cm vs. 2.3 {+-} 0.4 cm, p = 0.69). The diameters of the descending aorta were slightly smaller in UAV compared to TAV (2.2 {+-} 0.5 cm vs. 2.6 {+-} 0.3 cm, p < 0.05). (orig.)

Variable valve timing in a homogenous charge compression ignition engine

Science.gov (United States)

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

2004-08-03

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

Shape memory alloy actuated accumulator for ultra-deepwater oil and gas exploration

Science.gov (United States)

Patil, Devendra; Song, Gangbing

2016-04-01

As offshore oil and gas exploration moves further offshore and into deeper waters to reach hydrocarbon reserves, it is becoming essential for the industry to develop more reliable and efficient hydraulic accumulators to supply pressured hydraulic fluid for various control and actuation operations, such as closing rams of blowout preventers and controlling subsea valves on the seafloor. By utilizing the shape memory effect property of nitinol, which is a type of shape memory alloy (SMA), an innovative SMA actuated hydraulic accumulator prototype has been developed and successfully tested at Smart Materials and Structure Laboratory at the University of Houston. Absence of gas in the developed SMA accumulator prototype makes it immune to hydrostatic head loss caused by water depth and thus reduces the number of accumulators required in deep water operations. Experiments with a feedback control have demonstrated that the proposed SMA actuated accumulator can provide precisely regulated pressurized fluids. Furthermore the potential use of ultracapacitors along with an embedded system to control the electric power supplied to SMA allows this accumulator to be an autonomous device for deployment. The developed SMA accumulator will make deepwater oil extraction systems more compact and cost effective.

NRC Information Notice No. 93-01: Accuracy of motor-operated valve diagnostic equipment manufactured by Liberty Technologies

International Nuclear Information System (INIS)

Grimes, B.K.

1993-01-01

Most licensees rely on MOV diagnostic equipment to provide information on the thrust delivered by the motor actuator in opening or closing its valve. The various types of MOV diagnostic equipment estimate valve stem thrust using different parameters, such as displacement of the spring pack or strain in the stem, mounting bolts, or yoke. Liberty Technologies has developed MOV diagnostic equipment, referred to as the Valve Operation Test and Evaluation System (VOTES), that estimates the thrust needed to open or close a valve based on strain of the valve yoke. The VOTES equipment derives thrust from yoke strain that has been calibrated to stem thrust using measured diametral strain of the valve stem and nominal engineering material properties. On October 2, 1992, Liberty Technologies notified the NRC that it had determined that two new factors can affect the thrust values obtained with its equipment. Those factors involve (1) the possible use of improper stem material constants and (2) the failure to account for a torque effect when the VOTES equipment is calibrated by measuring strain in the threaded portion of the valve stem. Liberty Technologies provided information on performing manual calculations to address these factors and stated that its new software, Version 2.3, assists in performing corrections to the thrust data

The influence of Marfans and bicuspid valves on outcomes following aortic valve reimplantation.

Science.gov (United States)

Martín, Carlos E; García Montero, Carlos; Serrano, Santiago-Fiz; González, Ana; Mingo, Susana; Moñivas, Vanessa; Centeno, Jorge; Forteza, Alberto

2017-10-01

We analyzed our early and midterm results with aortic valve reimplantation surgery to determine the influence of Marfan syndrome and bicuspid valves on outcomes with this technique. Between March 2004 and December 2015, 267 patients underwent aortic valve reimplantation operations. The mean diameter of the sinuses of Valsalva was 50 ± 3 mm and moderate/severe aortic regurgitation was present in 34.4% of these patients. A bicuspid aortic valve was present in 21% and 40% had Marfan syndrome. Overall 30-day mortality was 0.37% (1/267). Mean follow-up was 59.7 ± 38.7 months. Overall survival at 1, 3, and 5 years was 98 ± 8%, 98 ± 1%, and 94 ± 2%, respectively. Freedom from reoperation and aortic regurgitation >II was 99 ± 5%, 98 ± 8%, 96.7 ± 8%, and 99 ± 6%, 98 ± 1%, 98 ± 1%, respectively at 1, 3, and 5 years follow-up, with no differences between Marfan and bicuspid aortic valve groups. (p = 0.94 and p = 0.96, respectively). No endocarditis or thromboembolic complications were documented, and 93.6% of the patients did not receive any anticoagulation therapy. The reimplantation technique for aortic root aneurysms is associated with excellent clinical and functional outcomes at short and mid-term follow-up. © 2017 Wiley Periodicals, Inc.

Electromechanical actuation of buckypaper actuator: Material properties and performance relationships

International Nuclear Information System (INIS)

Cottinet, P.-J.; Souders, C.; Tsai, S.-Y.; Liang, R.; Wang, B.; Zhang, C.

2012-01-01

Carbon nanotubes can be assembled into macroscopic thin film materials called buckypapers. To incorporate buckypaper actuators into engineering systems, it is of high importance to understand their material property-actuation performance relationships in order to model and predict the behavior of these actuators. The electromechanical actuation of macroscopic buckypaper structures and their actuators, including single and multi-walled carbon nanotube buckypapers and aligned single-walled nanotube buckypapers, were analyzed and compared. From the experimental evidence, this Letter discusses the effects of the fundamental material properties, including Young modulus and electrical double layer properties, on actuation performance of the resultant actuators. -- Highlights: ► In this study we identified the figure of merit of the electromechanical conversion. ► Different type of buckypaper was realized and characterized for actuation properties. ► The results demonstrated the potential of Buckypapers/Nafion for actuation

Design, test and model of a hybrid magnetostrictive hydraulic actuator

International Nuclear Information System (INIS)

Chaudhuri, Anirban; Yoo, Jin-Hyeong; Wereley, Norman M

2009-01-01

The basic operation of hybrid hydraulic actuators involves high frequency bi-directional operation of an active material that is converted to uni-directional motion of hydraulic fluid using valves. A hybrid actuator was developed using magnetostrictive material Terfenol-D as the driving element and hydraulic oil as the working fluid. Two different lengths of Terfenol-D rod, 51 and 102 mm, with the same diameter, 12.7 mm, were used. Tests with no load and with load were carried out to measure the performance for uni-directional motion of the output piston at different pumping frequencies. The maximum no-load flow rates were 24.8 cm 3 s −1 and 22.7 cm 3 s −1 with the 51 mm and 102 mm long rods respectively, and the peaks were noted around 325 Hz pumping frequency. The blocked force of the actuator was close to 89 N in both cases. A key observation was that, at these high pumping frequencies, the inertial effects of the fluid mass dominate over the viscous effects and the problem becomes unsteady in nature. In this study, we also develop a mathematical model of the hydraulic hybrid actuator in the time domain to show the basic operational principle under varying conditions and to capture phenomena affecting system performance. Governing equations for the pumping piston and output shaft were obtained from force equilibrium considerations, while compressibility of the working fluid was taken into account by incorporating the bulk modulus. Fluid inertia was represented by a lumped parameter approach to the transmission line model, giving rise to strongly coupled ordinary differential equations. The model was then used to calculate the no-load velocities of the actuator at different pumping frequencies and simulation results were compared with experimental data for model validation

Statins for aortic valve stenosis

Directory of Open Access Journals (Sweden)

Luciana Thiago

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

Statins for aortic valve stenosis.

Science.gov (United States)

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

2016-01-01

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

A grayscale pneumatic micro-valve for use in a reconfigurable tactile tablet for vision-impaired individuals

International Nuclear Information System (INIS)

Schneider, Joseph Devin; Rebolledo-Mendez, Jovan David; McNamara, Shamus

2015-01-01

The design, fabrication, and characterization of a strained bilayer film for use in a micro-valve for a reconfigurable tactile tablet for vision-impaired individuals is presented. The bilayer film consists of a compressive and tensile layer to cause the film to coil and retract from the gas channel when the micro-valve is in the open position. A novel support structure that improves yield and controls the direction of coiling is demonstrated. An array of 225 strained bilayer films was designed and fabricated. Each strained bilayer film was able to be actuated individually with a voltage that ranged between 60 and 70 V. The relationship between the applied voltage and the percentage open of the micro-valve is found to be linear over an extended voltage range, enabling the reconfigurable tactile tablet to produce the equivalent of a grayscale image. (paper)

Ministernotomy: A preliminary experience in heart valve surgery

Directory of Open Access Journals (Sweden)

Kovačević Pavle

2011-01-01

Full Text Available Background/Aim. The last decade of the 20th century brought up a significant development in the field of minimally invasive approaches to the valvular heart surgery. Potential benefits of this method are: good esthetic appearance, reduced pain, reduction of postoperative hemorrhage and incidence of surgical site infection, shorter postoperative intensive care units (ICU period and overall in-hospital period. Partial upper median sternotomy currently presents as a state-of-the art method for minimally invasive surgery of cardiac valves. The aim of this study was to report on initial experience in application of this surgical method in the surgery of mitral and aortic valves. Methods. The study was designed and conducted in a prospective manner and included all the patients who underwent minimally invasive cardiac valve surgery through the partial upper median sternotomy during the period November 2008 - August 2009. We analyzed the data on mean age of patients, mean extubation time, mean postoperative drainage, mean duration of hospital stay, as well as on occurance of postoperative complications (postoperative bleeding, surgical site infection and cerebrovascular insult. Results. During the observed period, in the Institute for Cardiovascular Diseases of Vojvodina, Clinic for Cardiovascular Surgery, 17 ministernotomies were performed, with 14 aortic valve replacements (82.35% and 3 mitral valve replacements (17.65%. Mean age of the patients was 60.78 ± 12.99 years (64.71% males, 35.29% females. Mean extubation time was 12.53 ± 8.87 hours with 23.5% of the patients extubated in less than 8 hours. Mean duration of hospital stay was 12.35 ± 10.17 days (in 29.4% of the patients less than 8 days. Mean postoperative drainage was 547.06 ± 335.2 mL. Postoperative complications included: bleeding (5.88% and cerebrovascular insult (5.88%. One patient (5.88% required conversion to full sternotomy. Conclusion. Partial upper median sternotomy represents

Actuator with Multi Degrees of Freedom(Actuator)

OpenAIRE

矢野, 智昭; Tomoaki, YANO; 産業技術総合研究所

2006-01-01

The advantages, problems and the recent developments of the actuator with multi degrees of freedom are presented. At first, the advantages of the actuator with multi degrees of freedom are described. Next, the problems needed to solve for practical use are presented. The recent applications of the actuator with multi degrees of freedom are also reviewed.

Lymphangiogenesis is increased in heart valve endocarditis.

Science.gov (United States)

Niinimäki, Eetu; Mennander, Ari A; Paavonen, Timo; Kholová, Ivana

2016-09-15

Inflammation-associated lymphangiogenesis (IAL) has been identified as part of several acute and chronic inflammation. Sparse data exist on lymphatics during endocarditis. Fifty-two patients with surgically resected valves were included. Endocarditis was present in 18 aortic and 10 mitral valves. Controls consisted of 15 degenerative aortic and 9 degenerative mitral valves. There were 22 males with endocarditis and 17 males in controls. The mean age was 58 (SD 15) years with endocarditis vs. 62 (SD 13) years for controls. Lymphatics were detected by podoplanin antibody immunohistochemistry and morphometrical analysis was performed. The lymphatic density in endocarditis was 833 (SD 529) vessels/mm(2) (range 0-1707) as compared with 39 (SD 60) vessels/mm(2) (range 0-250) in controls (p=0.000). In endocarditis, the mean lymphatic size was 153 (SD 372) μm(2) ranging from 1 to 2034μm(2), whereas it was 30 (SD 29) μm(2), with maximum 90μm(2) and minimum 2μm(2) in controls (p=0.000). IAL is increased in valves with endocarditis as compared with controls. Lymphatics in heart valves may provide a novel means for treatment strategies against endocarditis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Compact, planar, translational piezoelectric bimorph actuator with Archimedes’ spiral actuating tethers

International Nuclear Information System (INIS)

Yang, Chenye; Liu, Sanwei; Livermore, Carol; Xie, Xin

2016-01-01

The design, analytical modelling, finite element analysis (FEA), and experimental characterization of a microelectromechanical system (MEMS) out-of-plane (vertical) translational piezoelectric lead–zirconate–titanate (PZT) bimorph actuator supported on Archimedes’ spiral tethers are presented. Three types of bimorph actuators with different electrode patterns (with spiral tethers half actuated, fully actuated with uniform polarity, or fully actuated with reversed polarity) are designed and modelled. The two actuators with the highest predicted performance (half actuated and fully actuated with uniform polarity) are implemented and characterized. Both designs are fabricated by commercial processes and are compatible with integration into more complex MEMS systems. Analytical modelling and FEA are used to analyze and predict the actuators’ displacements and blocking forces. Experimental measurements of the deflections and blocking forces of actuators with full uniform actuation and half actuation validate the design. At an applied voltage of 110 V, the out-of-plane deflections of the actuators with half actuation and full uniform actuation are measured at about 17 µ m and 29 µ m respectively, in good agreement with analytical predictions of 17.3 µ m and 34.2 µ m and FEA predictions of 17.1 µ m and 25.8 µ m. The blocking force for devices with half-actuated tethers is predicted to be 12 mN (analytical) and 10 mN (FEA), close to the experimental value of 9 mN. The blocking force for devices with full uniform actuation is predicted to be 23 mN (analytical) and 17 mN (FEA), as compared with 15 mN in experiments. (paper)

Force measurements of a magnetic micro actuator proposed for a microvalve array

International Nuclear Information System (INIS)

Chang, Pauline J; Chang, Frank W; Yuen, Michelle C; Horsley, David A; Otillar, Robert

2014-01-01

Low-cost, easily-fabricated and power-efficient microvalves are necessary for many microfluidic lab-on-a-chip applications. In this study, we present a simple, low-power, scalable, CMOS-compatible magnetic actuator for microvalve applications composed of a paramagnetic bead as the ball valve over a picoliter reaction well etched into a silicon substrate. The paramagnetic bead, composed of either pure FeSi or magnetite in a SiO 2  matrix, is actuated by the local magnetic field gradient generated by a microcoil in an aqueous environment, and the reaction well is situated at the microcoil center. A permanent magnet beneath the microvalve device provides an external magnetic biasing field that magnetizes the bead, enabling bidirectional actuation and reducing the current required to actuate the bead to a level below 10 mA. The vertical and radial magnetic forces exerted on the bead by the microcoil were measured for both pure FeSi and composite beads and agree well with the predictions of 2D axisymmetric finite element method models. Vertical forces were within a range of 13–80 nN, and radial forces were 11–60 nN depending on the bead type. The threshold current required to initiate bead actuation was measured as a function of bead diameter and is found to scale inversely with volume for small beads, as expected based on the magnetic force model. To provide an estimate of the stiction force acting between the bead and the passivation layer on the substrate, repeated actuation trials were used to study the bead throw distance for substrates coated with silicon dioxide, Parylene-C, and photoresist. The stiction observed was lowest for a photoresist-coated substrate, while silicon dioxide and Parylene-C coated substrates exhibited similar levels of stiction. (paper)

Unicuspid aortic valve disease: a magnetic resonance imaging study

International Nuclear Information System (INIS)

Debl, K.; Buchner, S.; Heinicke, N.; Riegger, G.; Luchner, A.; Djavidani, B.; Poschenrieder, F.; Feuerbach, S.; Schmid, C.; Kobuch, R.

2008-01-01

Purpose: congenitally malformed aortic valves are a common finding in adults with aortic valve disease. Most of these patients have bicuspid aortic valve disease. Unicuspid aortic valve disease (UAV) is rare. The aim of our study was to describe valve morphology and the dimensions of the proximal aorta in a cohort of 12 patients with UAV in comparison to tricuspid aortic valve disease (TAV) using magnetic resonance imaging (MRI). Materials and methods/results: MRI studies were performed on a 1.5 T scanner in a total of 288 consecutive patients with aortic valve disease. 12 aortic valves were retrospectively classified as UAV. Annulus areas and dimensions of the thoracic aorta were retrospectively compared to a cohort of 103 patients with TAV. In UAV, valve morphology was unicuspid unicommissural with a posterior commissure in all patients. Mean annulus areas and mean diameters of the ascending aorta were significantly greater in UAV compared to TAV (12.6 ± 4.7 cm 2 vs. 8.7 ± 2.3 cm 2 , p < 0.01 and 4.6 ± 0.7 cm vs. 3.6 ± 0.5 cm, p < 0.0001, respectively), while no differences were observed in the mean diameters of the aortic arch (2.3 ± 0.6 cm vs. 2.3 ± 0.4 cm, p = 0.69). The diameters of the descending aorta were slightly smaller in UAV compared to TAV (2.2 ± 0.5 cm vs. 2.6 ± 0.3 cm, p < 0.05). (orig.)

Modernizing the 5G 100/8 piston compressor by means of directly streaming valves

Energy Technology Data Exchange (ETDEWEB)

Tsvetanov, Ts.; Stoyanov, I.

1988-02-01

Deals with 5G 100/8 air compressors which, despite long service and lack of spare parts, are still widely used in Bulgarian underground coal mines. K-4-10 ring-type valves are in particularly short supply; maintenance engineers have been forced to modify the compresors. Initially, Bulgarian KP-3.1 valves with direct air streaming replaced the K-4-10; these were later replaced by PIK-220 and PIK-220A valves. Tests on overhauled compressors have shown that replacing the KP-3.1 with the PIK-220 or PIK-220A can result in a saving of up to 100,000 kWh of electricity per compressor. Details of reconstruction and testing of piston compressors are included. 10 refs.

A light writable microfluidic "flash memory": optically addressed actuator array with latched operation for microfluidic applications.

Science.gov (United States)

Hua, Zhishan; Pal, Rohit; Srivannavit, Onnop; Burns, Mark A; Gulari, Erdogan

2008-03-01

This paper presents a novel optically addressed microactuator array (microfluidic "flash memory") with latched operation. Analogous to the address-data bus mediated memory address protocol in electronics, the microactuator array consists of individual phase-change based actuators addressed by localized heating through focused light patterns (address bus), which can be provided by a modified projector or high power laser pointer. A common pressure manifold (data bus) for the entire array is used to generate large deflections of the phase change actuators in the molten phase. The use of phase change material as the working media enables latched operation of the actuator array. After the initial light "writing" during which the phase is temporarily changed to molten, the actuated status is self-maintained by the solid phase of the actuator without power and pressure inputs. The microfluidic flash memory can be re-configured by a new light illumination pattern and common pressure signal. The proposed approach can achieve actuation of arbitrary units in a large-scale array without the need for complex external equipment such as solenoid valves and electrical modules, which leads to significantly simplified system implementation and compact system size. The proposed work therefore provides a flexible, energy-efficient, and low cost multiplexing solution for microfluidic applications based on physical displacements. As an example, the use of the latched microactuator array as "normally closed" or "normally open" microvalves is demonstrated. The phase-change wax is fully encapsulated and thus immune from contamination issues in fluidic environments.

Bio-inspired aquatic robotics by untethered piezohydroelastic actuation

International Nuclear Information System (INIS)

Cen, L; Erturk, A

2013-01-01

This paper investigates fish-like aquatic robotics using flexible bimorphs made of macro-fiber composite (MFC) piezoelectric laminates for carangiform locomotion. In addition to noiseless and efficient actuation over a range of frequencies, geometric scalability, and simple design, bimorph propulsors made of MFCs offer a balance between the actuation force and velocity response for performance enhancement in bio-inspired swimming. The experimental component of the presented work focuses on the characterization of an elastically constrained MFC bimorph propulsor for thrust generation in quiescent water as well as the development of a robotic fish prototype combining a microcontroller and a printed-circuit-board amplifier to generate high actuation voltage for untethered locomotion. From the theoretical standpoint, a distributed-parameter electroelastic model including the hydrodynamic effects and actuator dynamics is coupled with the elongated-body theory for predicting the mean thrust in quiescent water. In-air and underwater experiments are performed to verify the incorporation of hydrodynamic effects in the linear actuation regime. For electroelastically nonlinear actuation levels, experimentally obtained underwater vibration response is coupled with the elongated-body theory to predict the thrust output. The measured mean thrust levels in quiescent water (on the order of ∼10 mN) compare favorably with thrust levels of biological fish. An untethered robotic fish prototype that employs a single bimorph fin (caudal fin) for straight swimming and turning motions is developed and tested in free locomotion. A swimming speed of 0.3 body-length/second (7.5 cm s −1 swimming speed for 24.3 cm body length) is achieved at 5 Hz for a non-optimized main body-propulsor bimorph combination under a moderate actuation voltage level. (paper)

Efficiency of aortic valve commissurotomy for congenital aortic valve stenosis in pediatric population

Directory of Open Access Journals (Sweden)

А. А. Лукьянов

2015-10-01

Full Text Available Background. This study was designed to evaluate short-term and long-term outcomes after open aortic valve commissurotomy in the pediatric patients at our center over a period of 10 years. Methods. A retrospective study of 94 patients who underwent open surgical commissurotomy because of aortic valve stenosis between 2003 and 2013 is presented. Follow-up time was in the range of 1 to 7 years. Results. The open aortic valve commissurotomy combined with debridement of leaflet free edge 36.1 %, LVOT myectomy 11.7%, leaflet suture plastic 7.4%, modified Konno procedure 6.3%, Brom's aortoplasty 4.2% was performed for all patients. Average cardiopulmonary bypass time was 59.2 30.7 min. Median aortic cross-clamping time was 31.52 15.1 min. Hospital complications were observed in 38.2% of cases. ICU time was in the range of 1 to 31 (mean 3.2 5.1 day. Artificial lung ventilation time varied from 2 to 76 (mean 15.3 18.3 hours. Inotropic support was needed in 26.5% of cases. Mean hospital stay time was 17.1 7.3 days. At follow-up between 2 and 7 years, reoperations were required for 3 patients who underwent a Ross procedure. Conclusions. The results evidence that open surgical commissurotomy is an effective way of treatment for aortic valve stenosis, considering the accuracy of plasty and additional techniques of leaflet correction. The best children age group for this type of operation is from first to five years of life.

Failure analysis of the worm gear of the actuator of the motor-valve 2-N71-MV-1867; Analisis de falla del tornillo sin fin del actuador de la motovalvula 2-N71-MV-1867

Energy Technology Data Exchange (ETDEWEB)

Robles P, E. F.; Vazquez B, S.; Medina A, A. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Mar M, S. P., E-mail: eduardo.robles@inin.gob.mx [Comision Federal de Electricidad, Central Nucleoelectrica Laguna Verde, Carretera Cardel-Nautla Km 42.5, Veracruz (Mexico)

2011-11-15

In this work the results of the tests realized to the worm gear of the actuator of the motor-valve type butterfly 2-N71-MV-1867 coming from the nuclear power plant of Laguna Verde area presented, to determine the failure mechanism that caused the fracture of two of their wires. These wires present a lines model of irregular contact, what suggests the existence of non alignment in the gear-wheel system. The chemical analysis by means of optical emission spectrophotometry showed that the worm gear was manufactured starting from steel grade machinery AISI 4320H. The metallographic analysis corroborated that the chord of the worm gear was hardened superficially by means of a thermochemistry treatment of cemented, reaching a maximum hardness of cemented layer in the contact area of 58 HRC and a thickness of effective layer of 1.2 mm, also the presence of carbides precipitated in grain limits in the cemented layer was found, that which is not desirable because this increases its fragility. Likewise in the nucleus a tempering structure too much soft was revealed, 22 HRC. The analysis of the extracted fracture surfaces of the cracked areas during the operation of the worm gear, they suggest that the fracture mechanism was the fatigue of the material, which was generated starting from an em brittle cemented surface and it is spread inside a nucleus of low mechanical resistance. (Author)

Polymer/inorganic superhydrophobic surfaces.

Energy Technology Data Exchange (ETDEWEB)

Collord, Andrew; Kissel, David J.; Brinker, C. Jeffrey; Apblett, Christopher Alan; Branson, Eric D.

2009-09-01

We have designed and built electrostatically actuated microvalves compatible with integration into a PDMS based microfluidic system. The key innovation for electrostatic actuation was the incorporation of carbon nanotubes into the PDMS valve membrane, allowing for electrostatic charging of the PDMS layer and subsequent discharging, while still allowing for significant distention of the valveseat for low voltage control of the system. Nanoparticles were applied to semi-cured PDMS using a stamp transfer method, and then cured fully to make the valve seats. DC actuation in air of these valves yielded operational voltages as low as 15V, by using a supporting structure above the valve seat that allowed sufficient restoring forces to be applied while not enhancing actuation forces to raise the valve actuation potential. Both actuate to open and actuate to close valves have been demonstrated, and integrated into a microfluidic platform, and demonstrated fluidic control using electrostatic valves.

Flow Rate Analysis of 3/2 Directional Pneumatic Valve by Means Of Ansys Cfx Software

Directory of Open Access Journals (Sweden)

Slawomir BLASIAK

2014-12-01

Full Text Available The main purpose of this paper was to develop a selection method of the pneumatic connectors for directional 3/2 valve. The method was established to minimize resistance and loss of pressure in the valve with mounted pneumatic connections for the selected pipe diameters. Directional valve was modeled in 3D CAD software SolidWorks while 3D models of the air connections have been downloaded from the website of one of the leading suppliers of pneumatic. Based on developed solid model the simulation of compressed air flow in the software for computational fluid dynamics Ansys CFX was conducted. The studies using CFD methods helped to determine which air connections best meet the assumptions. Performed numerical tests enable proper selection of items to the newly designed pneumatic systems for a particular group of valves. As a consequence, this translates into a reduction in energy consumption and improve the efficiency of the entire pneumatic complex system.

Depth of valve implantation, conduction disturbances and pacemaker implantation with CoreValve and CoreValve Accutrak system for Transcatheter Aortic Valve Implantation, a multi-center study.

Science.gov (United States)

Lenders, Guy D; Collas, Valérie; Hernandez, José Maria; Legrand, Victor; Danenberg, Haim D; den Heijer, Peter; Rodrigus, Inez E; Paelinck, Bernard P; Vrints, Christiaan J; Bosmans, Johan M

2014-10-20

Transcatheter Aortic Valve Implantation (TAVI) is now considered an indispensable treatment strategy in high operative risk patients with severe, symptomatic aortic stenosis. However, conduction disturbances and the need for Permanent Pacemaker (PPM) implantation after TAVI with the CoreValve prosthesis still remain frequent. We aimed to evaluate the implantation depth, the incidence and predictors of new conduction disturbances, and the need for PPM implantation within the first month after TAVI, using the new Accutrak CoreValve delivery system (ACV), compared to the previous generation CoreValve (non-ACV). In 5 experienced TAVI-centers, a total of 120 consecutive non-ACV and 112 consecutive ACV patients were included (n=232). The mean depth of valve implantation (DVI) was 8.4±4.0 mm in the non-ACV group and 7.1±4.0 mm in the ACV group (p=0.034). The combined incidence of new PPM implantation and new LBBB was 71.2% in the non-ACV group compared to 50.5% in the ACV group (p=0.014). DVI (p=0.002), first degree AV block (p=0.018) and RBBB (p<0.001) were independent predictors of PPM implantation. DVI (p<0.001) and pre-existing first degree AV-block (p=0.021) were identified as significant predictors of new LBBB. DVI is an independent predictor of TAVI-related conduction disturbances and can be reduced by using the newer CoreValve Accutrak delivery system, resulting in a significantly lower incidence of new LBBB and new PPM implantation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

A study on a characteristic of stem friction coefficient for motor operated flexible wedge gate valve

International Nuclear Information System (INIS)

Kim, Dae-Woong; Park, Sung-Geun; Lee, Sang-Guk; Kang, Shin-Cheul

2009-01-01

Stem friction coefficient is a coefficient that represents friction between thread leads of the stem and stem nut. It is an important factor to determine output thrust delivered from the actuator to the valve stem in assessing performance of motor operated valves. This study analyzes the effects of changes in differential pressure on stem friction coefficient, and determines the bounding value of stem friction coefficient. A dynamic test was conducted on multiple flexible wedge gate valves in various differential pressure conditions, and the test data was statistically analyzed to determine the bounding value. The results show that stem friction coefficient in middle and high differential pressure is influenced by fluid pressure, while stem friction coefficient in low differential pressure is almost not affected by fluid pressure. In addition, it is found that the bounding value of stem friction coefficient is higher in a closing stroke than in an opening stroke.

Postoperative Outcomes of Mitral Valve Repair for Mitral Restenosis after Percutaneous Balloon Mitral Valvotomy

Directory of Open Access Journals (Sweden)

Seong Lee

2015-10-01

Full Text Available Background: There have been a number of studies on mitral valve replacement and repeated percutaneous mitral balloon valvotomy for mitral valve restenosis after percutaneous mitral balloon valvotomy. However, studies on mitral valve repair for these patients are rare. In this study, we analyzed postoperative outcomes of mitral valve repair for mitral valve restenosis after percutaneous mitral balloon valvotomy. Methods: In this study, we assessed 15 patients (mean age, 47.7±9.7 years; 11 female and 4 male who underwent mitral valve repair between August 2008 and March 2013 for symptomatic mitral valve restenosis after percutaneous mitral balloon valvotomy. The mean interval between the initial percutaneous mitral balloon valvotomy and the mitral valve repair was 13.5±7 years. The mean preoperative Wilkins score was 9.4±2.6. Results: The mean mitral valve area obtained using planimetry increased from 1.16±0.16 cm2 to 1.62±0.34 cm2 (p=0.0001. The mean pressure half time obtained using Doppler ultrasound decreased from 202.4±58.6 ms to 152±50.2 ms (p=0.0001. The mean pressure gradient obtained using Doppler ultrasound decreased from 9.4±4.0 mmHg to 5.8±1.5 mmHg (p=0.0021. There were no early or late deaths. Thromboembolic events or infective endocarditis did not occur. Reoperations such as mitral valve repair or mitral valve replacement were not performed during the follow-up period (39±16 months. The 5-year event-free survival was 56.16% (95% confidence interval, 47.467–64.866. Conclusion: On the basis of these results, we could not conclude that mitral valve repair could be an alternative for patients with mitral valve restenosis after percutaneous balloon mitral valvotomy. However, some patients presented with results similar to those of mitral valve replacement. Further studies including more patients with long-term follow-up are necessary to determine the possibility of this application of mitral valve repair.

Check valves aging assessment

International Nuclear Information System (INIS)

Haynes, H.D.

1991-01-01

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

Evaluation of piezoceramic actuators for control of aircraft interior noise

Science.gov (United States)

Silcox, Richard J.; Lefebvre, Sylvie; Metcalf, Vern L.; Beyer, Todd B.; Fuller, Chris R.

1992-01-01

Results of an experiment to evaluate piezoceramic actuators as the control actuator for active control of interior noise in a large-scale fuselage model are presented. Control was demonstrated for tonal excitation using a time domain least mean squares algorithm. A maximum of four actuator channels and six error signals were used. The actuators were employed for control of noise at frequencies where interior cavity modes were the dominant response and for driven acoustic responses where a structure resonance was dominant. Global reductions of 9 to 12 dB were obtained for the cases examined. The most effective configuration of skin-mounted actuators was found to be a pure in-plane forcing function as opposed to a bending excitation. The frame-mounted actuators were found to be equally effective as the skin-mounted actuators. However, both configurations resulted in local regions of unacceptably high vibration response in the structure.

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

Science.gov (United States)

Davis, R. Benjamin; Fischbach, Sean R.

2010-01-01

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

Isolating valve, especially in main-steam pipes of power plants

International Nuclear Information System (INIS)

Karpenko, A.N.

1977-01-01

The valve for PWRs and BWRs, with diameters up to 1.25 m, for temperatures from -180 0 C to about 600 0 C and pressures up to over 50 bar, is designed for high reliability and long useful life. Two circular valve discs are moved as isolating elements in their plane across the steam direction and brought before the valve seat within a valve chamber. Shortly before reaching this final position, each disc is rotated by a small amount about its axis. Only after reaching the final position a double-wedge, further pushed forward between both discs, produces the necessary contact pressure. By revolving and frictionless closing caking together at high stresses and temperature variation is prevented and permanent tightness assured. The valve body is moved in a cylinder, cast on the valve housing, by means of a stepped piston. Its larger diameter is guided in a second cylinder flanged on above. In the cover of the second cylinder a pilot valve is mounted being controlled over 2 parallel solenoid valves by means of compressed air. In normal operation process steam from the valve chamber serves to move the stepped piston with the valve chamber. On closing of a bore, connecting both cylinder spaces, by the pilot valve the main valve is opened. If the pilot valve is opened the steam through the connecting bore is acting on both piston stages and closing the main valve. On loss of steam (pipe break) or for testing purposes one or the other cylinder space over solenoid valves is acted upon by auxiliary energy or evacuated, the main valve thus being controlled. (HP) [de

Plastik på trikuspidalklappen (Tricuspid valve annuloplasty. The neglected valve)

DEFF Research Database (Denmark)

Pedersen, Thais A L; Wierup, Per; Pedersen, Lia Mendes

2010-01-01

INTRODUCTION: Tricuspid valve regurgitation (TVR) is often secondary to left-sided or congenital heart disease (CHD). Surgical correction of TVR is indicated when the primary abnormalities require operation. MATERIAL AND METHODS: Retrospective analysis of all 50 patients (mean age: 65 years (rang...

Reduced-impact sliding pressure control valve for pneumatic hammer drill

Science.gov (United States)

Polsky, Yarom [Oak Ridge, TN; Grubelich, Mark C [Albuquerque, NM; Vaughn, Mark R [Albuquerque, NM

2012-05-15

A method and means of minimizing the effect of elastic valve recoil in impact applications, such as percussive drilling, where sliding spool valves used inside the percussive device are subject to poor positioning control due to elastic recoil effects experienced when the valve impacts a stroke limiting surface. The improved valve design reduces the reflected velocity of the valve by using either an energy damping material, or a valve assembly with internal damping built-in, to dissipate the compression stress wave produced during impact.

Note: A novel rotary actuator driven by only one piezoelectric actuator.

Science.gov (United States)

Huang, Hu; Fu, Lu; Zhao, Hongwei; Shi, Chengli; Ren, Luquan; Li, Jianping; Qu, Han

2013-09-01

This paper presents a novel piezo-driven rotary actuator based on the parasitic motion principle. Output performances of the rotary actuator were tested and discussed. Experiment results indicate that using only one piezoelectric actuator and simple sawtooth wave control, the rotary actuator reaches the rotation velocity of about 20,097 μrad/s when the driving voltage is 100 V and the driving frequency is 90 Hz. The actuator can rotate stably with the minimum resolution of 0.7 μrad. This paper verifies feasibility of the parasitic motion principle for applications of rotary actuators, providing new design ideas for precision piezoelectric rotary actuators.

Transcatheter aortic valve implantation for failing surgical aortic bioprosthetic valve: from concept to clinical application and evaluation (part 2).

Science.gov (United States)

Piazza, Nicolo; Bleiziffer, Sabine; Brockmann, Gernot; Hendrick, Ruge; Deutsch, Marcus-André; Opitz, Anke; Mazzitelli, Domenico; Tassani-Prell, Peter; Schreiber, Christian; Lange, Rüdiger

2011-07-01

This study sought to review the acute procedural outcomes of patients who underwent transcatheter aortic valve (TAV)-in-surgical aortic valve (SAV) implantation at the German Heart Center, Munich, and to summarize the existing literature on TAV-in-SAV implantation (n = 47). There are several case reports and small case series describing transcatheter aortic valve implantation for a failing surgical aortic valve bioprosthesis (TAV-in-SAV implantation). From January 2007 to March 2011, 20 out of 556 patients underwent a TAV-in-SAV implantation at the German Heart Center Munich. Baseline characteristics and clinical outcome data were prospectively entered into a dedicated database. The mean patient age was 75 ± 13 years, and the mean logistic European System for Cardiac Operative Risk Evaluation and Society of Thoracic Surgeons' Risk Model scores were 27 ± 13% and 7 ± 4%, respectively. Of the 20 patients, 14 had stented and 6 had stentless surgical bioprostheses. Most cases (12 of 20) were performed via the transapical route using a 23-mm Edwards Sapien prosthesis (Edwards Lifesciences, Irvine, California). Successful implantation of a TAV in a SAV with the patient leaving the catheterization laboratory alive was achieved in 18 of 20 patients. The mean transaortic valve gradient was 20.0 ± 7.5 mm Hg. None-to-trivial, mild, and mild-to-moderate paravalvular aortic regurgitation was observed in 10, 6, and 2 patients, respectively. We experienced 1 intraprocedural death following pre-implant balloon aortic valvuloplasty ("stone heart") and 2 further in-hospital deaths due to myocardial infarction. TAV-in-SAV implantation is a safe and feasible treatment for high-risk patients with failing aortic bioprosthetic valves and should be considered as part of the armamentarium in the treatment of aortic bioprosthetic valve failure. Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Pump integrated closed loop control. The intelligent actuator pump - state of the art and perspectives; Pumpenintegrierte Prozessregelung. Der intelligente Aktor Pumpe - Stand und Moeglichkeiten

Energy Technology Data Exchange (ETDEWEB)

Paulus, Thomas; Schullerer, Joachim; Oesterle, Manfred [KSB AG, Frankenthal (Germany)

2009-07-01

In many areas of industrial automation, centrifugal pumps and systems of centrifugal pumps are important actuators of a process und therefore a fundamental part of the entire plant. In contrary to the controlled valves, located behind the pump in the pipework system, the functions of the intelligent actuator pump or system of pumps are rarely used and noticed. With regard to the reduction of life cycle costs of the asset pump, pump integrated closed loop control of the fluid transport task has advantages over central closed loop control e.g. in a process control system. This article contains a survey of the intelligent actuator pump, its structure and functions with regard to the solution of the fluid transport task and according pump integrated closed loop control. (orig.)

Aortic Regurgitation in Patients Undergoing Transcatheter Aortic Valve Replacement With the Self-Expanding CoreValve Versus the Balloon-Expandable SAPIEN XT Valve.

Science.gov (United States)

Kiramijyan, Sarkis; Magalhaes, Marco A; Koifman, Edward; Didier, Romain; Escarcega, Ricardo O; Baker, Nevin C; Negi, Smita I; Minha, Sa'ar; Torguson, Rebecca; Jiaxiang, Gai; Asch, Federico M; Wang, Zuyue; Okubagzi, Petros; Gaglia, Michael A; Ben-Dor, Itsik; Satler, Lowell F; Pichard, Augusto D; Waksman, Ron

2016-05-01

The incidence of aortic regurgitation (AR) after transcatheter aortic valve replacement (TAVR) in a self-expanding and a balloon-expandable system is controversial. This study aimed to examine the incidence and severity of post-TAVR AR with the CoreValve (CV) versus the Edwards XT Valve (XT). Baseline, procedural, and postprocedural inhospital outcomes were compared. The primary end point was the incidence of post-TAVR AR of any severity, assessed with a transthoracic echocardiogram, in the CV versus XT groups. A multivariate logistic regression analysis was completed to evaluate for correlates of the primary end point. The secondary end points included the change in severity of AR at 30-day and 1-year follow-up. A total of 223 consecutive patients (53% men, mean age 82 years) who had transfemoral TAVR with either a CV (n = 119) or XT (n = 104) were evaluated. The rates of post-TAVR AR in the groups were similar, and there was no evidence of more-than-moderate AR in either group. There were significant differences in the rates of intraprocedural balloon postdilation with the CV (17.1%) versus XT valve (5.8%; p = 0.009) and in the rates of intraprocedural implantation of a second valve-in-valve prosthesis with the CV (9.9%) versus XT valve (2.2%; p = 0.036). There were no significant differences in inhospital safety outcomes between the 2 groups. In conclusion, the incidence of post-TAVR AR is similar between the CV and the XT valve when performed by experienced operators using optimal intraprocedural strategies, as deemed appropriate, to mitigate the severity of AR. Copyright © 2016 Elsevier Inc. All rights reserved.

EMC design for actuators in the FAST reflector

Science.gov (United States)

Zhang, Hai-Yan; Wu, Ming-Chang; Yue, You-Ling; Gan, Heng-Qian; Hu, Hao; Huang, Shi-Jie

2018-04-01

An active reflector is one of the three main innovations incorporated in the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The deformation of such a huge spherically shaped reflector into different transient parabolic shapes is achieved by using 2225 hydraulic actuators which change the position of the 2225 nodes through the connected down tied cables. For each different tracking process of the telescope, more than 1/3 of these 2225 actuators must be in operation to tune the parabolic aperture accurately and meet the surface error restriction. This means that some of these actuators are inevitably located within the main beam of the receiver, and Electromagnetic Interference (EMI) from the actuators must be mitigated to ensure the scientific output of the telescope. Based on the threshold level of interference detrimental to radio astronomy described in ITU-R Recommendation RA.769 and EMI measurements, the shielding efficiency (SE) requirement for each actuator is set to be 80 dB in the frequency range from 70 MHz to 3 GHz. Therefore, Electromagnetic Compatibility (EMC) was taken into account in the actuator design by measures such as power line filters, optical fibers, shielding enclosures and other structural measures. In 2015, all the actuators had been installed at the FAST site. Till now, no apparent EMI from the actuators has been detected by the receiver, which demonstrates the effectiveness of these EMC measures.

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

Science.gov (United States)

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

2017-10-13

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

A STUDY OF INDICATIONS, COMPLICATIONS OF PROSTHETIC VALVES AND PROGNOSIS AFTER TREATMENT OF STUCK VALVE

Directory of Open Access Journals (Sweden)

Y. V. Subba Reddy

2017-03-01

Full Text Available BACKGROUND Implantation of prosthetic cardiac valves to treat haemodynamically significant valvular diseases has become common; however, it is associated with complications. Thus, this study was intended to evaluate the indications for implantation of prosthetic valve and complications after its implantation and prognosis after treatment of one of its complication, i.e. stuck valve. MATERIALS AND METHODS This was a single-centered study wherein 50 patients who came to the emergency department with stuck valve were assessed. The 2D echocardiography was performed in all patients. Thrombolysis was done and the gradients were reassessed. Further response to treatment and development of complications before and after treatment were observed. RESULTS Of total patients, 60% were females. Mean age group was 30-40 yrs. Most of them were asymptomatic for 6 years and there was lack of compliance in 90% of patients. Most common indication for valve replacement was mitral stenosis (60% followed by mitral regurgitation (20%, aortic regurgitation and aortic stenosis (10% and combined mitral and tricuspid regurgitation (10%. Commonest valve was St. Jude (90%. Pannus was observed in 10% patients and thrombus was observed in 50% patients. Most patients had gradients 45/20 mmHg across mitral valve. In about 90% patients, gradients decreased after thrombolysis (12/5 mmHg. The complications after thrombolysis were hemiparesis (4%, death before thrombolysis (6% and death after thrombolysis (4%. CONCLUSION Considering these results, it can be concluded that prosthetic valves are seldom associated with some complications. Further, thrombolysis can be effective in patients with prosthetic valve thrombosis.

Remotely powered and controlled EAPap actuator by amplitude modulated microwaves

International Nuclear Information System (INIS)

Yang, Sang Yeol; Mahadeva, Suresha K; Kim, Jaehwan

2013-01-01

This paper reports on a remotely powered and controlled Electro-Active Paper (EAPap) actuator without onboard controller using amplitude modulated microwaves. A rectenna is a key element for microwave power transmission that converts microwaves into dc power through coupling and rectification. In this study, the concept of a remotely controlled and powered EAPap actuator is proposed by means of modulating microwaves with a control signal and demodulating it through the rectenna rectification. This concept is applied to a robust EAPap actuator, namely cellulose–polypyrrole–ionic liquid (CPIL) EAPap. Details of fabrication and characterization of the rectenna and the CPIL-EAPap actuator are explained. Also, the charge accumulation problem of the actuator is explained and resolved by connecting an additional resistor. Since this idea can eliminate the onboard controller by supplying the operating signal through modulation, a compact and lightweight actuator can be achieved, which is useful for biomimetic robots and remotely driven actuators. (technical note)

First report on a human percutaneous transluminal implantation of a self-expanding valve prosthesis for interventional treatment of aortic valve stenosis.

Science.gov (United States)

Grube, Eberhard; Laborde, Jean C; Zickmann, Bernfried; Gerckens, Ulrich; Felderhoff, Thomas; Sauren, Barthel; Bootsveld, Andreas; Buellesfeld, Lutz; Iversen, Stein

2005-12-01

Percutaneous aortic valve replacement is a new technology for the treatment of patients with significant aortic valve stenosis. We present the first report on a human implantation of a self-expanding aortic valve prosthesis, which is composed of three bovine pericardial leaflets inserted within a self-expanding nitinol stent. The 73-year-old woman presented with severe symptomatic aortic valve stenosis (mean transvalvular gradient of 45 mmHg; valve area of 0.7 cm2). Surgical valve replacement had been declined for the patient because of comorbidities, including previous bypass surgery. A retrograde approach via the common iliac artery was used for valve deployment. The contralateral femoral vessels were used for a temporary extracorporal circulation, unloading the left ventricle during the actual stent expansion. Clinical, hemodynamic, and echocardiographic outcomes were assessed serially during the procedure. Clinical and echocardiographic follow-up at day 1, 2, and 14 post procedure was performed to evaluate the short-term outcome. The prosthesis was successfully deployed within the native aortic valve, with accurate and stable positioning and with no impairment of the coronary artery or vein graft blood flow. 2D and doppler echo immediately after device deployment showed a significant reduction in transaortic mean pressure gradient (from 45 to 8 mmHg) without evidence of aortic or mitral valve insufficiency. The clinical status has then significantly improved. These results remained unchanged up to the day 14 follow-up. This case report demonstrates a successful percutaneous implantation of a self-expanding aortic valve prosthesis with remarkable functional and clinical improvements in the acute and short-term outcome. Copyright (c) 2005 Wiley-Liss, Inc.

Perspectives of the fully variable valve train univalve on the basis of a 2.0 l spark-ignition engine; Perspektiven des vollvariablen Ventiltriebs Univalve auf Basis eines 2,0-l-Ottomotors

Energy Technology Data Exchange (ETDEWEB)

Flierl, R. [Lehrstuhl fuer Verbrennungskraftmaschinen der Technischen Univ. Kaiserslautern (Germany); Entec Consulting GmbH, Hemer (Germany); Gollasch, D. [Lehrstuhl fuer Verbrennungsmotoren der Univ. Kaiserslautern (Germany); Knecht, A.; Pohl, D. [Hydraulik-Ring GmbH, Nuertingen (Germany); Hannibal, W. [Lab. fuer Konstruktion und CAE-Anwendungen, Fachhochschule Suedwestfalen, Iserlohn (Germany); Entec Consulting GmbH, Hemer (Germany)

2006-07-15

This article provides the first test results of a fired four cylinder gasoline engin with the new fully variable valve timing system 'Univalve'. This variable valve actuation system is under development by the Hilite / Hydraulik-Ring company for series production engines. The basic investigations are taking place at the University of Kaiserslautern at the institute of combustion engines. Only by changes at the intake valve train, the fuel consumption could be improved by 13% compared to the otherwise identical basic engine. Essential engine functions like torque and emissions were also clearly improved. (orig.)

Flight control actuation system

Science.gov (United States)

Wingett, Paul T. (Inventor); Gaines, Louie T. (Inventor); Evans, Paul S. (Inventor); Kern, James I. (Inventor)

2006-01-01

A flight control actuation system comprises a controller, electromechanical actuator and a pneumatic actuator. During normal operation, only the electromechanical actuator is needed to operate a flight control surface. When the electromechanical actuator load level exceeds 40 amps positive, the controller activates the pneumatic actuator to offset electromechanical actuator loads to assist the manipulation of flight control surfaces. The assistance from the pneumatic load assist actuator enables the use of an electromechanical actuator that is smaller in size and mass, requires less power, needs less cooling processes, achieves high output forces and adapts to electrical current variations. The flight control actuation system is adapted for aircraft, spacecraft, missiles, and other flight vehicles, especially flight vehicles that are large in size and travel at high velocities.

Failure of cargo aileron’s actuator

Directory of Open Access Journals (Sweden)

G. Zucca

2014-10-01

Full Text Available During a ferry flight, in a standard operation condition and at cruising level, a military cargo experienced a double hydraulic system failure due to a structural damage of the dual booster actuator. The booster actuator is the main component in mechanism of aileron’s deflection. The crew was able to arrange an emergency landing thanks to the spare oil onboard: load specialists refilled the hydraulic reservoirs. Due to safety concerns and in order to prevent the possibility of other similar incidents, a technical investigation took place. The study aimed to carry out the analysis of root causes of the actuator failure. The Booster actuator is composed mainly by the piston rod and its aluminum external case (AA7049. The assembly has two bronze caps on both ends. These are fixed in position by means of two retainers. At one end of the actuator case is placed a trunnion: a cylindrical protrusion used as a pivoting point on the aircraft. The fracture was located at one end of the case, on the trunnion side, in correspondence to the cap and over the retainer. One of the two fracture surfaces was found separated to the case and with the cap entangled inside. The fracture surfaces of the external case indicated fatigue crack growth followed by ductile separation. The failure analysis was performed by means of optical, metallographic, digital and electronic microscopy. The collected evidences showed a multiple initiation fracture mechanism. Moreover, 3D scanner reconstruction and numerical simulation demonstrated that dimensional non conformances and thermal loads caused an abnormal stress concentration. Stress concentration was located along the case assy outer surface where the fatigue crack originated. The progressive rupture mechanism grew under cyclical axial load due to the normal operations. Recommendations were issued in order to improve dimensional controls and assembly procedures during production and overhaul activities.

Experimental investigations on the fluid-mechanics of an electrospun heart valve by means of particle image velocimetry.

Science.gov (United States)

Del Gaudio, Costantino; Gasbarroni, Pier Luca; Romano, Giovanni Paolo

2016-12-01

End-stage failing heart valves are currently replaced by mechanical or biological prostheses. Both types positively contribute to restore the physiological function of native valves, but a number of drawbacks limits the expected performances. In order to improve the outcome, tissue engineering can offer an alternative approach to design and fabricate innovative heart valves capable to support the requested function and to promote the formation of a novel, viable and correctly operating physiological structure. This potential result is particularly critical if referred to the aortic valve, being the one mainly exposed to structural and functional degeneration. In this regard, the here proposed study presents the fabrication and in vitro characterization of a bioresorbable electrospun heart valve prosthesis using the particle image velocimetry technique either in physiological and pathological fluid dynamic conditions. The scaffold was designed to reproduce the aortic valve geometry, also mimicking the fibrous structure of the natural extracellular matrix. To evaluate its performances for possible implantation, the flow fields downstream the valve were accurately investigated and compared. The experimental results showed a correct functionality of the device, supported by the formation of vortex structures at the edge of the three cusps, with Reynolds stress values below the threshold for the risk of hemolysis (which can be comprised in the range 400-4000N/m(2) depending on the exposure period), and a good structural resistance to the mechanical loads generated by the driving pressure difference. Copyright © 2016 Elsevier Ltd. All rights reserved.

Soft Robotic Actuators

Science.gov (United States)

Godfrey, Juleon Taylor

In this thesis a survey on soft robotic actuators is conducted. The actuators are classified into three main categories: Pneumatic Artificial Muscles (PAM), Electronic Electroactive Polymers (Electric EAP), and Ionic Electroactive Polymers (Ionic EAP). Soft robots can have many degrees and are more compliant than hard robots. This makes them suitable for applications that are difficult for hard robots. For each actuator background history, build materials, how they operate, and modeling are presented. Multiple actuators in each class are reviewed highlighting both their use and their mathematical formulation. In addition to the survey the McKibben actuator was chosen for fabrication and in-depth experimental analysis. Four McKibben actuators were fabricated using mesh sleeve, barbed hose fittings, and different elastic bladders. All were actuated using compressed air. Tensile tests were performed for each actuator to measure the tension force as air pressure increased from 20 to 100 psi in 10 psi increments. To account for material relaxation properties eleven trials for each actuator were run for 2-3 days. In conclusion, the smallest outer diameter elastic bladder was capable of producing the highest force due to the larger gap between the bladder and the sleeve.

Fluid-driven reciprocating apparatus and valving for controlling same

Science.gov (United States)

Whitehead, John C.; Toews, Hans G.

1993-01-01

A control valve assembly for alternately actuating a pair of fluid-driven free-piston devices by using fluid pressure communication therebetween. Each control valve is switched by a pressure signal depending on the state of its counterpart's piston. The communication logic is arranged to provide overlap of the forward strokes of the pistons, so that at least one of the pair will always be pressurized. Thus, uninterrupted pumping of liquid is made possible from a pair of free-piston pumps. In addition, the speed and frequency of piston stroking is entirely dependent on the mechanical power load applied. In the case of a pair of pumps, this enables liquid delivery at a substantially constant pressure over the full range of flow rates, from zero to maximum flow. One embodiment of the invention utilized two pairs of fluid-driven free-piston devices whereby a bipropellant liquid propulsion system may be operated, so as to provide continuous flow of both fuel and oxidizer liquids when used in rocket applications, for example.

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

Energy Technology Data Exchange (ETDEWEB)

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

2007-10-15

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

The new Toyota variable valve timing and lift system

Energy Technology Data Exchange (ETDEWEB)

Shimizu, K.; Fuwa, N.; Yoshihara, Y. [Toyota Motor Corporation (Japan); Hori, K. [Toyota Boshoku Corporation (Japan)

2007-07-01

A continuously variable valve timing (duration and phase) and lift system was developed. This system was applied to the valvetrain of a new 2.0L L4 engine (3ZRFAE) for the Japanese market. The system has rocker arms, which allow continuously variable timing and lift, situated between a conventional roller-rocker arm and the camshaft, an electromotor actuator to drive it and a phase mechanism for intake and exhaust camshafts (Dual VVT-i). The rocking center of the rocker arm is stationary, and the axial linear motion of a helical spline changes the initial phase of the rocker arm which varies the timing and lift. The linear motion mechanism uses an original planetary roller screw and is driven by a brushless motor with a built-in electric control unit. Since the rocking center and the linear motion helical spline center coincide, a compact cylinder head design was possible, and the cylinder head is a common design with a conventional engine. Since the ECU controls intake valve duration and timing, a fuel economy gain of maximum 10% (depending on driving condition) is obtained by reducing light to medium load pumping losses. Also intake efficiency was maximized throughout the speed range, resulting in a power gain of 10%. Further, HC emissions were reduced due to increased air speed at low valve lift. (orig.)

Aortic root surgery in Marfan syndrome: Bentall procedure with the composite mechanical valved conduit versus aortic valve reimplantation with Valsalva graft.

Science.gov (United States)

Nardi, Paolo; Pellegrino, Antonio; Versaci, Francesco; Mantione, Ludmilla; Polisca, Patrizio; Iorio, Fiore S; Chiariello, Luigi

2010-09-01

The aim of the study is to compare mid-term results of Bentall aortic root replacement with composite mechanical valved conduit and aortic valve reimplantation procedure using the Valsalva graft for the treatment of aortic root aneurysm in patients with Marfan syndrome. We retrospectively compared data of 23 patients (mean age 38 + or - 14 years) who had undergone the Bentall procedure (group B) to those of 24 patients (mean age 36 + or - 12 years) who had undergone aortic valve reimplantation (group R) during a 14-year period. Follow-up (mean duration 65 + or - 44 months) was 100% complete. There were no operative deaths in either group. In group B, as compared with group R, preoperative aortic insufficiency (3.2 + or - 1.1/4 vs. 1.7 + or - 1.4/4, P Marfan patients, the Bentall procedure is associated with excellent mid-term outcome. The reimplantation technique, adopted for less dilated aortas, provides similarly satisfactory results. The Valsalva graft seems, with time, to allow a stable aortic valve function.

Check valve

Science.gov (United States)

Upton, H.A.; Garcia, P.

1999-08-24

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

Check valve

International Nuclear Information System (INIS)

Upton, H.A.; Garcia, P.

1999-01-01

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

Advanced Launch System (ALS): Electrical actuation and power systems improve operability and cost picture

Science.gov (United States)

Sundberg, Gale R.

1990-01-01

To obtain the Advanced Launch System (ALS) primary goals of reduced costs and improved operability, there must be significant reductions in the launch operations and servicing requirements relative to current vehicle designs and practices. One of the primary methods for achieving these goals is by using vehicle electrical power system and controls for all actuation and avionics requirements. A brief status review of the ALS and its associated Advanced Development Program is presented to demonstrate maturation of those technologies that will help meet the overall operability and cost goals. The electric power and actuation systems are highlighted as a specific technology ready not only to meet the stringent ALS goals (cryogenic field valves and thrust vector controls with peak power demands to 75 hp), but also those of other launch vehicles, military and civilian aircraft, lunar/Martian vehicles, and a multitude of commercial applications.

Degenerative processes in bioprosthetic mitral valves in juvenile pigs

Directory of Open Access Journals (Sweden)

Pedersen Torben B

2011-05-01

Full Text Available Abstract Background Glutaraldehyde-treated bioprosthetic heart valves are commonly used for replacement of diseased heart valves. However, calcification and wear limit their durability, and the development of new and improved bioprosthetic valve designs is needed and must be evaluated in a reliable animal model. We studied glutaraldehyde-treated valves 6 months after implantation to evaluate bioprosthetic valve complications in the mitral position in juvenile pigs. Materials The study material comprised eight, 5-month old, 60-kg pigs. All pigs received a size 27, glutaraldehyde-treated, stented, Carpentier-Edwards S.A.V. mitral valve prosthesis. After six months, echocardiography was performed, and the valves explanted for gross examination, high resolution X-ray, and histological evaluation. Results Five pigs survived the follow-up period. Preexplant echocardiography revealed a median peak and mean velocity of 1.61 m/s (range: 1.17-2.00 and 1.20 (SD = ±0.25, respectively, and a median peak and mean pressure difference of 10.42 mmHg (range: 5.83-16.55 and 6.51 mmHg (SD = ±2.57, respectively. Gross examination showed minor thrombotic depositions at two commissures in two valves and at all three commissures in three valves. High resolution X-ray imaging revealed different degrees of calcification in all explanted valves, primarily in the commissural and belly areas. In all valves, histological evaluation demonstrated various degrees of fibrous sheath formation, limited immunological infiltration, and no overgrowth of host endothelium. Conclusions Bioprosthetic glutaraldehyde-treated mitral valves can be implanted into the mitral position in pigs and function after 6 months. Echocardiographic data, calcification, and histological examinations were comparable to results obtained in sheep models and human demonstrating the suitability of the porcine model.

NRC valve performance test program - check valve testing

International Nuclear Information System (INIS)

Jeanmougin, N.M.

1987-01-01

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

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

Directory of Open Access Journals (Sweden)

Harish Ramakrishna

2015-01-01

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

Considerations for Contractile Electroactive Materials and Actuators

Energy Technology Data Exchange (ETDEWEB)

Lenore Rasmussen, David Schramm, Paul Rasmussen, Kevin Mullaly, Ras Labs, LLC, Intelligent Materials for Prosthetics & Automation, Lewis D. Meixler, Daniel Pearlman and Alice Kirk

2011-05-23

Ras Labs produces contractile electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input, which can be cycled. This phenomenon was explored using molecular modeling, followed by experimentation. Applied voltage step functions were also investigated. High voltage steps followed by low voltage steps produced a larger contraction followed by a smaller contraction. Actuator control by simply adjusting the electric input is extremely useful for biomimetic applications. Muscles are able to partially contract. If muscles could only completely contract, nobody could hold an egg, for example, without breaking it. A combination of high and low voltage step functions could produce gross motor function and fine manipulation within the same actuator unit. Plasma treated electrodes with various geometries were investigated as a means of providing for more durable actuation.

Transcatheter Replacement of Failed Bioprosthetic Valves

DEFF Research Database (Denmark)

Simonato, Matheus; Webb, John; Kornowski, Ran

2016-01-01

postprocedural gradients (mean >= 20 mm Hg). Optimal implantation depths were defined by receiver operating characteristic curve. A total of 292 consecutive patients (age, 78.9 +/- 8.7 years; 60.3% male; 157 CoreValve Evolut and 135 Sapien XT) were evaluated. High implantation was associated with significantly...... lower rates of elevated gradients in comparison with low implantation (CoreValve Evolut, 15% versus 34.2%; P=0.03 and Sapien XT, 18.5% versus 43.5%; P=0.03, respectively). Optimal implantation depths were defined: CoreValve Evolut, 0 to 5 mm; Sapien XT, 0 to 2 mm (0-10% frame height); sensitivities, 91...

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

DEFF Research Database (Denmark)

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

2014-01-01

Digital Displacement (DD) fluid power machines are upcoming technology, improving the efficiency compared to traditional variable displacement machines, especially at low displacements where currently available fluid power pumps/motors suffer from mediocre efficiency. This efficiency improvement...... is made possible using independent electronically controlled seat valves for each pressure chamber, which is controlled corresponding to the rotation of the crankshaft. By control of these pressure chamber seat valves, the total displacement are controlled in discrete steps, and the pressure chambers...... not contributing to the displacement are not pressurized, which has been shown to improve the efficiency. To make this type of displacement control possible and energy efficient, the seat valves must be fast switching (ms range) and exhibit a very low pressure loss during operation, setting strict requirements...

Investigation and Development of the Thermal Preparation System of the Trailbuilder Machinery Hydraulic Actuator

Science.gov (United States)

Konev, V.; Polovnikov, E.; Krut, O.; Merdanov, Sh; Zakirzakov, G.

2017-07-01

It’s determined that the main part of trailbuilders operated in the North is the technology equipped by the hydraulic actuator. Further development of the northern territories will demand using of various means and ways machinery thermal preparation, and also the machinery of the northern fulfillment. On this basis problems in equipment operation are defined. One of the main is efficiency supplying of a hydraulic actuator. On the basis of the operating conditions’ analysis of trailbuilder hydraulic actuator operation it is determined, that under low negative temperatures the means of thermal preparation are necessary. The existing systems warm up only a hydraulic tank or warming up of the hydro equipment before the machinery operation is carried out under loading with intensive wears. Thus, with the purpose to raise the efficiency of thermal hydraulic actuator, operated far from stationary bases autonomous, energy saving, not expensive in creation and operation systems are necessary. In accordance with the analysis of means and ways of the thermal preparation of the hydraulic actuator and the thermal balance calculations of the (internal) combustion engine the system of the hydraulic actuator heating is offered and is being investigated. It contains a local hydraulic actuator warming up and the system of internal combustion engine heat utilization. Within research operation conditions of the local hydraulic actuator heating are viewed and determined, taking into account constructive changes to the local hydraulic actuator heating. Mathematical modelling of the heat technical process in the modernized hydraulic actuator is considered. As a result temperature changes of the heat-transfer and the hydraulic cylinder in time are determined. To check the theoretical researches and to define dependences on hydraulic actuator warming up, the experimental installation is made. It contains the measuring equipment, a small tank with the heat exchanger of the burnt gases

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

Science.gov (United States)

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

2012-01-01

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

Curved Piezoelectric Actuators for Stretching Optical Fibers

Science.gov (United States)

Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

2008-01-01

Assemblies containing curved piezoceramic fiber composite actuators have been invented as means of stretching optical fibers by amounts that depend on applied drive voltages. Piezoceramic fiber composite actuators are conventionally manufactured as sheets or ribbons that are flat and flexible, but can be made curved to obtain load-carrying ability and displacement greater than those obtainable from the flat versions. In the primary embodiment of this invention, piezoceramic fibers are oriented parallel to the direction of longitudinal displacement of the actuators so that application of drive voltage causes the actuator to flatten, producing maximum motion. Actuator motion can be transmitted to the optical fiber by use of hinges and clamp blocks. In the original application of this invention, the optical fiber contains a Bragg grating and the purpose of the controlled stretching of the fiber is to tune the grating as part of a small, lightweight, mode-hop-free, rapidly tunable laser for demodulating strain in Bragg-grating strain-measurement optical fibers attached to structures. The invention could also be used to apply controllable tensile force or displacement to an object other than an optical fiber.

Development of PZT Actuated Valveless Micropump

Directory of Open Access Journals (Sweden)

Fathima Rehana Munas

2018-04-01

Full Text Available A piezoelectrically actuated valveless micropump has been designed and developed. The principle components of this system are piezoelectrically actuated (PZT metal diaphragms and a complete fluid flow system. The design of this pump mainly focuses on a cross junction, which is generated by a nozzle jet attached to a pump chamber and the intersection of two inlet channels and an outlet channel respectively. During each PZT diaphragm vibration cycle, the junction connecting the inlet and outlet channels with the nozzle jet permits consistencies in fluidic momentum and resistances in order to facilitate complete fluidic path throughout the system, in the absence of any physical valves. The entire micropump structure is fabricated as a plate-by-plate element of polymethyl methacrylate (PMMA sheets and sandwiched to get required fluidic network as well as the overall device. In order to identify the flow characteristics, and to validate the test results with numerical simulation data, FEM analysis using ANSYS was carried out and an eigenfrequency analysis was performed to the PZT diaphragm using COMSOL Multiphysics. In addition, the control system of the pump was designed and developed to change the applied frequency to the piezoelectric diaphragms. The experimental data revealed that the maximum flow rate is 31.15 mL/min at a frequency of 100 Hz. Our proposed design is not only for a specific application but also useful in a wide range of biomedical applications.

Development of PZT Actuated Valveless Micropump.

Science.gov (United States)

Munas, Fathima Rehana; Melroy, Gehan; Abeynayake, Chamitha Bhagya; Chathuranga, Hiniduma Liyanage; Amarasinghe, Ranjith; Kumarage, Pubudu; Dau, Van Thanh; Dao, Dzung Viet

2018-04-24

A piezoelectrically actuated valveless micropump has been designed and developed. The principle components of this system are piezoelectrically actuated (PZT) metal diaphragms and a complete fluid flow system. The design of this pump mainly focuses on a cross junction, which is generated by a nozzle jet attached to a pump chamber and the intersection of two inlet channels and an outlet channel respectively. During each PZT diaphragm vibration cycle, the junction connecting the inlet and outlet channels with the nozzle jet permits consistencies in fluidic momentum and resistances in order to facilitate complete fluidic path throughout the system, in the absence of any physical valves. The entire micropump structure is fabricated as a plate-by-plate element of polymethyl methacrylate (PMMA) sheets and sandwiched to get required fluidic network as well as the overall device. In order to identify the flow characteristics, and to validate the test results with numerical simulation data, FEM analysis using ANSYS was carried out and an eigenfrequency analysis was performed to the PZT diaphragm using COMSOL Multiphysics. In addition, the control system of the pump was designed and developed to change the applied frequency to the piezoelectric diaphragms. The experimental data revealed that the maximum flow rate is 31.15 mL/min at a frequency of 100 Hz. Our proposed design is not only for a specific application but also useful in a wide range of biomedical applications.

Reoperation for non-structural valvular dysfunction caused by pannus ingrowth in aortic valve prosthesis.

Science.gov (United States)

Oh, Se Jin; Park, Samina; Kim, Jun Sung; Kim, Kyung-Hwan; Kim, Ki Bong; Ahn, Hyuk

2013-07-01

The authors' clinical experience is presented of non-structural valvular dysfunction of the prosthetic aortic valve caused by pannus ingrowth during the late postoperative period after previous heart valve surgery. Between January 1999 and April 2012, at the authors' institution, a total of 33 patients underwent reoperation for increased mean pressure gradient of the prosthetic aortic valve. All patients were shown to have pannus ingrowth. The mean interval from the previous operation was 16.7 +/- 4.3 years, and the most common etiology for the previous aortic valve replacement (AVR) was rheumatic valve disease. The mean effective orifice area index (EOAI) of the previous prosthetic valve was 0.97 +/- 0.11 cm2/m2, and the mean pressure gradient on the aortic prosthesis before reoperation was 39.1 +/- 10.7 mmHg. Two patients (6.1%) died in-hospital, and late death occurred in six patients (18.2%). At the first operation, 30 patients underwent mitral or tricuspid valve surgery as a concomitant procedure. Among these operations, mitral valve replacement (MVR) was combined in 24 of all 26 patients with rheumatic valve disease. Four patients underwent pannus removal only while the prosthetic aortic valve was left in place. The mean EOAI after reoperation was significantly increased to 1.16 +/- 0.16 cm2/m2 (p pannus ingrowth was shown in patients with a small EOAI of the prosthetic aortic valve and combined MVR for rheumatic disease. As reoperation for pannus overgrowth showed good clinical outcomes, an aggressive resection of pannus and repeated AVR should be considered in symptomatic patients to avoid the complications of other cardiac diseases.

A COMPUTATIONAL STUDY OF THE ACTUATION SPEED OF THE HYDRAULIC CYLINDER UNDER DIFFERENT PORTS’ SIZES AND CONFIGURATIONS

Directory of Open Access Journals (Sweden)

M. O. ABDALLA

2015-02-01

Full Text Available The discharged oil from hydraulic cylinder, during its operation, is highly restricted by the small sized outlets. As a result, a back pressure builds up and the piston motion, therefore, is slowed down; the system pump has to do additional work to overcome this hydraulic resistance so as to preserve the required speed. In this study the possibility of improvement of the actuation speed of the hydraulic cylinders was investigated and analysed. Both a four-port cylinder and a resized-ports cylinder were proposed as fast cylinders. FLUENT 6.3 was used for the simulation of the oil flow field of the hydraulic cylinders. Results showed that relation between discharge flow and the outlets diameters is best described by a power law having coefficients partially depending on the system pressure. It had also shown that for any given total outlet area, the actuation speed of the single outlet cylinders is always higher than that of the double outlets cylinders. In one case where the total outlet area is 3.93E-05m2, the actuation speed of the single outlet cylinder is 21% higher than that of the double outlets cylinder; whereas, when doubling the total outlet area the different is reduced to just 6% . Resizing the outlet for small ports was more efficient than using multi-outlets; while for a large ports it shows no significant difference to use either one outlet port or multi-outlets. Both the solutions of resizing or ports addition need special valve to be fit to the cylinder so that the cylinder could be effectively operated under the control of the proportional valve.

Transapical aortic valve implantation without angiography: proof of concept.

Science.gov (United States)

Ferrari, Enrico; Sulzer, Christopher; Marcucci, Carlo; Rizzo, Elena; Tozzi, Piergiorgio; von Segesser, Ludwig K

2010-06-01

Cardiac computed tomographic scans, coronary angiograms, and aortographies are routinely performed in transcatheter heart valve therapies. Consequently, all patients are exposed to multiple contrast injections with a following risk of nephrotoxicity and postoperative renal failure. The transapical aortic valve implantation without angiography can prevent contrast-related complications. Between November 2008 and November 2009, 30 consecutive high-risk patients (16 female, 53.3%) underwent transapical aortic valve implantation without angiography. The landmarks identification, the stent-valve positioning, and the postoperative control were routinely performed under transesophageal echocardiogram and fluoroscopic visualization without contrast injections. Mean age was 80.1 +/- 8.7 years. Mean valve gradient, aortic orifice area, and ejection fraction were 60.3 +/- 20.9 mm Hg, 0.7 +/- 0.16 cm(2), and 0.526 +/- 0.128, respectively. Risk factors were pulmonary hypertension (60%), peripheral vascular disease (70%), chronic pulmonary disease (50%), previous cardiac surgery (13.3%), and chronic renal insufficiency (40%) (mean blood creatinine and urea levels: 96.8 +/- 54 microg/dL and 8.45 +/- 5.15 mmol/L). Average European System for Cardiac Operative Risk Evaluation was 32.2 +/- 13.3%. Valve deployment in the ideal landing zone was 96.7% successful and valve embolization occurred once. Thirty-day mortality was 10% (3 patients). Causes of death were the following: intraoperative ventricular rupture (conversion to sternotomy), right ventricular failure, and bilateral pneumonia. Stroke occurred in one patient at postoperative day 9. Renal failure (postoperative mean blood creatinine and urea levels: 91.1 +/- 66.8 microg/dL and 7.27 +/- 3.45 mmol/L), myocardial infarction, and atrioventricular block were not detected. Transapical aortic valve implantation without angiography requires a short learning curve and can be performed routinely by experienced teams. Our report

Reversible thermo-pneumatic valves on centrifugal microfluidic platforms.

Science.gov (United States)

Aeinehvand, Mohammad Mahdi; Ibrahim, Fatimah; Harun, Sulaiman Wadi; Kazemzadeh, Amin; Rothan, Hussin A; Yusof, Rohana; Madou, Marc

2015-08-21

Centrifugal microfluidic systems utilize a conventional spindle motor to automate parallel biochemical assays on a single microfluidic disk. The integration of complex, sequential microfluidic procedures on these platforms relies on robust valving techniques that allow for the precise control and manipulation of fluid flow. The ability of valves to consistently return to their former conditions after each actuation plays a significant role in the real-time manipulation of fluidic operations. In this paper, we introduce an active valving technique that operates based on the deflection of a latex film with the potential for real-time flow manipulation in a wide range of operational spinning speeds. The reversible thermo-pneumatic valve (RTPV) seals or reopens an inlet when a trapped air volume is heated or cooled, respectively. The RTPV is a gas-impermeable valve composed of an air chamber enclosed by a latex membrane and a specially designed liquid transition chamber that enables the efficient usage of the applied thermal energy. Inputting thermo-pneumatic (TP) energy into the air chamber deflects the membrane into the liquid transition chamber against an inlet, sealing it and thus preventing fluid flow. From this point, a centrifugal pressure higher than the induced TP pressure in the air chamber reopens the fluid pathway. The behaviour of this newly introduced reversible valving system on a microfluidic disk is studied experimentally and theoretically over a range of rotational frequencies from 700 RPM to 2500 RPM. Furthermore, adding a physical component (e.g., a hemispherical rubber element) to induce initial flow resistance shifts the operational range of rotational frequencies of the RTPV to more than 6000 RPM. An analytical solution for the cooling of a heated RTPV on a spinning disk is also presented, which highlights the need for the future development of time-programmable RTPVs. Moreover, the reversibility and gas impermeability of the RTPV in the

Dynamic load in suppression pool during BWR main steam safety relief valve actuation

International Nuclear Information System (INIS)

Tsukada, Hiroshi; Yamaguchi, Hirokatsu; Morita, Terumichi

1979-01-01

BWRs are so designed that the exhaust steam from main steam safety relief valves is led to pressure suppression pools, and the steam is condensed in pool water, but at this time, dynamic load seems to arise in the pool water. In Tokai No. 2 Power Station, a Mark-2 containment vessel was adopted to improve the reliability as much as possible and to obtain the design with margin. In this report, the result of actual machine test in Tokai No. 2 Power Station and the method of reducing the load are described. When a relief valve works, the discharge of water in exhaust pipes into a suppression pool, the exhaust of air in exhaust pipes and repeated expansion and contraction of bubbles in pool water, and the exhaust of steam and condensation occur. As for the construction of the suppression pool in Tokai No. 2 Power Station, cross-shaped quencher and the structure with jet deflector were installed. The test plan and the test result with an actual machine are reported. The soundness of the Mark-2 containment vessel and the structures in the pool was proved. The differential pressure acting on the structures was negligibly small. The measured pulsating pressure was in the range from 0.84 to -0.39 kg/cm 2 . (Kako, I.)

Valve-sparing aortic root replacement†.

Science.gov (United States)

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

2015-02-01

To evaluate our results of valve-sparing aortic root replacement and associated (multiple) valve repair. From September 2003 to September 2013, 97 patients had valve-sparing aortic root replacement procedures. Patient records and preoperative, postoperative and recent echocardiograms were reviewed. Median age was 40.3 (range: 13.4-68.6) years and 67 (69.1%) were male. Seven (7.2%) patients were younger than 18 years, the youngest being 13.4 years. Fifty-four (55.7%) had Marfan syndrome, 2 (2.1%) other fibrous tissue diseases, 15 (15.5%) bicuspid aortic valve and 3 (3.1%) had earlier Fallot repair. The reimplantation technique was used in all, with a straight vascular prosthesis in 11 (26-34 mm) and the Valsalva prosthesis in 86 (26-32 mm). Concomitant aortic valve repair was performed in 43 (44.3%), mitral valve repair in 10 (10.3%), tricuspid valve repair in 5 (5.2%) and aortic arch replacement in 3 (3.1%). Mean follow-up was 4.2 ± 2.4 years. Follow-up was complete in all. One 14-year old patient died 1.3 years post-surgery presumably of ventricular arrhythmia. One patient underwent reoperation for aneurysm of the proximal right coronary artery after 4.9 years and 4 patients required aortic valve replacement, 3 of which because of endocarditis after 0.1, 0.8 and 1.3 years and 1 because of cusp prolapse after 3.8 years. No thrombo-embolic complications occurred. Mortality, root reoperation and aortic regurgitation were absent in 88.0 ± 0.5% at 5-year follow-up. Results of valve-sparing root replacement are good, even in association with a high incidence of concomitant valve repair. Valve-sparing aortic root replacement can be performed at a very young age as long as an adult size prosthesis can be implanted. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Supplement No. 79-01A to IE Bulletin No. 79-01: Environmental qualification of Class 1E equipment (Deficiencies in the environmental qualification of ASCO solenoid valves)

International Nuclear Information System (INIS)

Anon.

1993-01-01

Recently, a noncompliance report under 10 CFR Part 21 was received by the NRC from the Henry Pratt Company, manufacturer of butterfly valves which are installed in the primary containment at the Three Mile Island Unit 2 Nuclear Station. These butterfly valves are used for purge and exhaust purposes and are required to operate during accident conditions. The report discusses the use of an unqualified solenoid valve for a safety-related valve function which requires operation under accident conditions. The solenoid valve in question is Catalogue No. HT-8331A45, manufactured by the Automatic Switch Company (ASCO) of Florham Park, New Jersey. This pilot valve is used to pilot control the pneumatic valve actuators which are installed on the containment ventilation butterfly valves at this facility. The deficiency in these solenoid valves identified in the Part 21 Report concerns the parts made of acetal plastic material. The acetal disc holder assembly and bottom plug in the pilot valve assembly are stated by ASCO to have a maximum service limit of 400,000 Rad integrated dosage and 200 degrees F temperature. According to ASCO, exposure of these acetal plastic parts to specified maximum environmental conditions may render the solenoid pilot valve inoperable which would cause the associated butterfly valve to malfunction

Trabeculectomy With Mitomycin C or Ahmed Valve Implantation in Eyes With Uveitic Glaucoma.

Science.gov (United States)

Bettis, Daniel I; Morshedi, Richard G; Chaya, Craig; Goldsmith, Jason; Crandall, Alan; Zabriskie, Norm

2015-01-01

To report and compare the results of trabeculectomy with mitomycin C (MMC) and Ahmed valve implantation in the management of uveitic glaucoma. The records of 41 eyes of 29 patients who underwent trabeculectomy with MMC or Ahmed valve implantation for uveitic glaucoma were retrospectively reviewed. Seventeen eyes underwent trabeculectomy with MMC, and 24 eyes underwent Ahmed valve implantation. Outcomes included postoperative intraocular pressure (IOP), percent reduction from preoperative IOP, postoperative number of medications, time to failure, and complications. Mean follow-up was 21.2 months in the trabeculectomy group and 23.8 months in the valve group (P=0.06). Mean IOP was reduced from 29.2 to 18.4 mm Hg in the trabeculectomy group (31.3%), compared with a reduction from 33.4 to 15.5 mm Hg in the Ahmed valve group (42.7%, P=0.53). Postoperatively, 1.76 medications were used in the trabeculectomy group, compared with 1.83 medications in the Ahmed valve group (P=0.89). Cumulative success at 1 year was 66.7% in the trabeculectomy group, compared with 100% in the Ahmed valve group (P=0.02). Mean time to failure was 8.36 months with trabeculectomy, and 21.8 months with Ahmed valve (P=0.02). Complications in both groups were typically rare and self-limited, with recurrent inflammation being most common. Although both trabeculectomy with MMC and Ahmed valve implantation are reasonable surgical options in the management of uncontrolled uveitic glaucoma, Ahmed valve implantation was associated with higher cumulative success rate at 1 year and a longer mean time to failure.

Wafer-scale integration of piezoelectric actuation capabilities in nanoelectromechanical systems resonators

OpenAIRE

DEZEST, Denis; MATHIEU, Fabrice; MAZENQ, Laurent; SOYER, Caroline; COSTECALDE, Jean; REMIENS, Denis; THOMAS, Olivier; DEÜ, Jean-François; NICU, Liviu

2013-01-01

In this work, we demonstrate the integration of piezoelectric actuation means on arrays of nanocantilevers at the wafer scale. We use lead titanate zirconate (PZT) as piezoelectric material mainly because of its excellent actuation properties even when geometrically constrained at extreme scale

The safety relief valve handbook design and use of process safety valves to ASME and International codes and standards

CERN Document Server

Hellemans, Marc

2009-01-01

The Safety Valve Handbook is a professional reference for design, process, instrumentation, plant and maintenance engineers who work with fluid flow and transportation systems in the process industries, which covers the chemical, oil and gas, water, paper and pulp, food and bio products and energy sectors. It meets the need of engineers who have responsibilities for specifying, installing, inspecting or maintaining safety valves and flow control systems. It will also be an important reference for process safety and loss prevention engineers, environmental engineers, and plant and process designers who need to understand the operation of safety valves in a wider equipment or plant design context. . No other publication is dedicated to safety valves or to the extensive codes and standards that govern their installation and use. A single source means users save time in searching for specific information about safety valves. . The Safety Valve Handbook contains all of the vital technical and standards informat...

Condition monitoring of a check valve for nuclear power plants by means of acoustic emission technique

International Nuclear Information System (INIS)

Lee, Min Rae; Leee, Jun Hyun; Kim, Jung Tack; Kim, Jung Soo; Luk, V. K.

2003-01-01

This work performed in support of the International Nuclear Energy Research Initiative(INERI) program, which was to develop and demonstrate advanced sensor and computational technology for on-line monitoring of the condition of components, structures, and systems in advanced and next-generation nuclear power plants (NPPs). The primary object of this work is to investigate advanced condition monitoring systems based on acoustic emission detection that can provide timely detection of check valve degradation and service aging so that maintenance/replacement could be preformed prior to loss of safety function. The research is focused on the capability of AE technique to provide diagnostic information useful in determining check valve aging and degradation, check valve failures and undesirable operating modes. This work also includes the investigation and adaptation of several advanced sensor technologies such as accelerometer and advanced ultrasonic technique. In addition, this work will develop advanced sophisticated signal processing, noise reduction, and pattern recognition techniques and algorithms from check valve degradation.

Condition monitoring of a check valve for nuclear power plants by means of acoustic emission technique

International Nuclear Information System (INIS)

Lee, M. R.; Lee, J. H.; Kim, J. T.; Kim, J. S.; Luk, V. K.

2003-01-01

This work performed in support of the International Nuclear Energy Research Institute (INERI) program, which was to develop and demonstrate advanced sensor and computational technology for on-line monitoring of the condition of components, structures, and systems in advanced and next-generation nuclear power plants (NPPs). This primary object of this work is to investigate advanced condition monitoring systems based on acoustic emission detection that can provide timely detection of check valve degeneration and service aging so that maintenance/replacement could be preformed prior to loss safety function. The research is focused on the capability of AE technique to provide diagnostic information useful in determining check valve aging and degradation check valve failure and undesirable operating modes. This work also includes the investigation and adaptation of several advanced sensor technologies such as accelerometer and advanced ultrasonic technique. In addition, this work will develop advanced sophisticated signal processing, noise reduction, and pattern recognition techniques and algorithms from check valve degradation.

Early Outcomes of Sutureless Aortic Valves

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Muhammet Onur Hanedan

2016-06-01

Full Text Available Background: In elderly high-risk surgical patients, sutureless aortic valve replacement (AVR should be an alternative to standard AVR. The potential advantages of sutureless aortic prostheses include reducing cross-clamping and cardiopulmonary bypass (CPB time and facilitating minimally invasive surgery and complex cardiac interventions, while maintaining satisfactory hemodynamic outcomes and low rates of paravalvular leakage. The current study reports our single-center experience regarding the early outcomes of sutureless aortic valve implantation. Methods: Between October 2012 and June 2015, 65 patients scheduled for surgical valve replacement with symptomatic aortic valve disease and New York Heart Association function of class II or higher were included to this study. Perceval S (Sorin Biomedica Cardio Srl, Sallugia, Italy and Edwards Intuity (Edwards Lifesciences, Irvine, CA, USA valves were used. Results: The mean age of the patients was 71.15±8.60 years. Forty-four patients (67.7% were female. The average preoperative left ventricular ejection fraction was 56.9±9.93. The CPB time was 96.51±41.27 minutes and the cross-clamping time was 60.85±27.08 minutes. The intubation time was 8.95±4.19 hours, and the intensive care unit and hospital stays were 2.89±1.42 days and 7.86±1.42 days, respectively. The mean quantity of drainage from chest tubes was 407.69±149.28 mL. The hospital mortality rate was 3.1%. A total of five patients (7.69% died during follow-up. The mean follow-up time was 687.24±24.76 days. The one-year survival rate was over 90%. Conclusion: In the last few years, several models of valvular sutureless bioprostheses have been developed. The present study evaluating the single-center early outcomes of sutureless aortic valve implantation presents the results of an innovative surgical technique, finding that it resulted in appropriate hemodynamic conditions with acceptable ischemic time.

Early Outcomes of Sutureless Aortic Valves.

Science.gov (United States)

Hanedan, Muhammet Onur; Mataracı, İlker; Yürük, Mehmet Ali; Özer, Tanıl; Sayar, Ufuk; Arslan, Ali Kemal; Ziyrek, Uğur; Yücel, Murat

2016-06-01

In elderly high-risk surgical patients, sutureless aortic valve replacement (AVR) should be an alternative to standard AVR. The potential advantages of sutureless aortic prostheses include reducing cross-clamping and cardiopulmonary bypass (CPB) time and facilitating minimally invasive surgery and complex cardiac interventions, while maintaining satisfactory hemodynamic outcomes and low rates of paravalvular leakage. The current study reports our single-center experience regarding the early outcomes of sutureless aortic valve implantation. Between October 2012 and June 2015, 65 patients scheduled for surgical valve replacement with symptomatic aortic valve disease and New York Heart Association function of class II or higher were included to this study. Perceval S (Sorin Biomedica Cardio Srl, Sallugia, Italy) and Edwards Intuity (Edwards Lifesciences, Irvine, CA, USA) valves were used. The mean age of the patients was 71.15±8.60 years. Forty-four patients (67.7%) were female. The average preoperative left ventricular ejection fraction was 56.9±9.93. The CPB time was 96.51±41.27 minutes and the cross-clamping time was 60.85±27.08 minutes. The intubation time was 8.95±4.19 hours, and the intensive care unit and hospital stays were 2.89±1.42 days and 7.86±1.42 days, respectively. The mean quantity of drainage from chest tubes was 407.69±149.28 mL. The hospital mortality rate was 3.1%. A total of five patients (7.69%) died during follow-up. The mean follow-up time was 687.24±24.76 days. The one-year survival rate was over 90%. In the last few years, several models of valvular sutureless bioprostheses have been developed. The present study evaluating the single-center early outcomes of sutureless aortic valve implantation presents the results of an innovative surgical technique, finding that it resulted in appropriate hemodynamic conditions with acceptable ischemic time.

Bi-directional series-parallel elastic actuator and overlap of the actuation layers.

Science.gov (United States)

Furnémont, Raphaël; Mathijssen, Glenn; Verstraten, Tom; Lefeber, Dirk; Vanderborght, Bram

2016-01-27

Several robotics applications require high torque-to-weight ratio and energy efficient actuators. Progress in that direction was made by introducing compliant elements into the actuation. A large variety of actuators were developed such as series elastic actuators (SEAs), variable stiffness actuators and parallel elastic actuators (PEAs). SEAs can reduce the peak power while PEAs can reduce the torque requirement on the motor. Nonetheless, these actuators still cannot meet performances close to humans. To combine both advantages, the series parallel elastic actuator (SPEA) was developed. The principle is inspired from biological muscles. Muscles are composed of motor units, placed in parallel, which are variably recruited as the required effort increases. This biological principle is exploited in the SPEA, where springs (layers), placed in parallel, can be recruited one by one. This recruitment is performed by an intermittent mechanism. This paper presents the development of a SPEA using the MACCEPA principle with a self-closing mechanism. This actuator can deliver a bi-directional output torque, variable stiffness and reduced friction. The load on the motor can also be reduced, leading to a lower power consumption. The variable recruitment of the parallel springs can also be tuned in order to further decrease the consumption of the actuator for a given task. First, an explanation of the concept and a brief description of the prior work done will be given. Next, the design and the model of one of the layers will be presented. The working principle of the full actuator will then be given. At the end of this paper, experiments showing the electric consumption of the actuator will display the advantage of the SPEA over an equivalent stiff actuator.

Soft, Rotating Pneumatic Actuator.

Science.gov (United States)

Ainla, Alar; Verma, Mohit S; Yang, Dian; Whitesides, George M

2017-09-01

This article describes a soft pneumatic actuator that generates cyclical motion. The actuator consists of several (three, four, or five) chambers (arranged around the circumference of a circle surrounding a central rod) that can be actuated independently using negative pressure (or partial vacuum). Sequential actuation of the four-chamber device using reduced pressure moves the central rod cyclically in an approximately square path. We characterize the trajectory of the actuator and the force exerted by it, as we vary the material used for fabrication, the number of chambers, and the size of the actuator. We demonstrate two applications of this actuator: to deliver fluid while stirring (by replacing the central rod with a needle) and for locomotion that mimics a reptilian gait (by combining four actuators together).

Soft buckling actuators

Energy Technology Data Exchange (ETDEWEB)

Yang, Dian; Whitesides, George M.

2017-12-26

A soft actuator is described, including: a rotation center having a center of mass; a plurality of bucklable, elastic structural components each comprising a wall defining an axis along its longest dimension, the wall connected to the rotation center in a way that the axis is offset from the center of mass in a predetermined direction; and a plurality of cells each disposed between two adjacent bucklable, elastic structural components and configured for connection with a fluid inflation or deflation source; wherein upon the deflation of the cell, the bucklable, elastic structural components are configured to buckle in the predetermined direction. A soft actuating device including a plurality of the soft actuators and methods of actuation using the soft actuator or soft actuating device disclosed herein are also described.

Internal leakage detection in control valves; Detektion der inneren Leckage von Stellgeraeten

Energy Technology Data Exchange (ETDEWEB)

Kiesbauer, J. [SAMSON AG, Mess- und Regeltechnik, Frankfurt am Main (Germany). Entwicklungspruefstand; Hoffmann, H. [SAMSON AG, Mess- und Regeltechnik, Frankfurt am Main (Germany). Bereich Entwicklung

2000-07-01

Digital positioners offer a number of interesting features regarding improved process plant reliability and maintenance or servicing. This can provide the basis for using software tools for early fault diagnosis and performance visualization of control valves with extended functions, such as archiving the control valve's condition when new. It can be subjected to trend analyses as well as to preventative maintenance and servicing while in operation. Up to now, such systems cannot reliably predict the possible increase in internal leakage. Predictions can only be made about a possible change in the actuator's closing force and the zero point when the valve is closed. This article introduces a new and cost-effective leakage detector for control valves in combination with the binary input of a digital positioner which can signal the increase in internal leakage in the throttling area (e.g. caused by wear on the throttling element) of a control valve, if the valve is closed during operation. (orig.) [German] Digitale Stellungsregler bieten eine Reihe von interessanten Moeglichkeiten im Hinblick auf die Verbesserung der Prozesszuverlaessigkeit und der Wartung bzw. Instandhaltung. Auf dieser Basis koennen Softwaretools zur Fehlerfrueherkennung und zur Performance-Visualisierung bei Stellgeraeten mit weitergehender Funktionalitaet eingesetzt werden. Diese unterstuetzen z.B. die Archivierung des Neuzustandes des Stellgeraetes sowie die vorbeugende Wartung und Instandhaltung im laufenden Prozess bis hin zu Trendanalysen. Solche Systeme koennen bisher allerdings noch keine zuverlaessigen Aussagen ueber die eventuelle Zunahme der inneren Leckage machen. Aussagen sind nur moeglich ueber eventuelle Veraenderungen der Antriebsschliesskraft und des Nullpunktes bei geschlossenem Ventil. Dieser Beitrag stellt einen neuartigen kostenguenstigen Leckagedetektor fuer Stellgeraete in Kombination mit dem Binaereingang eines digitalen Stellungsreglers vor, welcher die erhoehte

Controllable valve in a nuclear reactor system

International Nuclear Information System (INIS)

Schabert, H.P.; Laurer, E.

1980-01-01

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

Anesthetic Management and Complications of Percutaneous Aortic Valve Implantation

Directory of Open Access Journals (Sweden)

Tailur Alberto Grando

2013-05-01

Full Text Available Background and objective: Aortic stenosis is a highly prevalent and life-threatening disease. In elderly patients with comorbidities, percutaneous valve implantation is an option. The aim of the study was to describe the anesthetic management and complications of general anesthesia Method: Case series with 30-day and 24-month follow-ups after implantation of the CoreValve device performed at the Institute of Cardiology/University Foundation of Cardiology between December 2008 and January 2012. The patients underwent general anesthesia monitored with mean arterial pressure (PAM, electrocardiogram (ECG, pulse oximetry, capnography, transesophageal echocardiography, thermometry, and transvenous pacemaker. Results: Twenty-eight patients, mean age 82.46 years, 20.98% mean EuroSCORE, functional class III/IV, successfully underwent valve implantation. Nine patients required permanent pacemaker implantation. During follow-up, two patients died: one during surgery due to LV perforation and the other on the third day of unknown causes. At 24 months, one patient diagnosed with multiple myeloma died. This anesthetic technique proved to be safe. Conclusion: The initial experience with percutaneous aortic valve implantation under general anesthesia has proven to be safe and effective, with no significant anesthetic complications during this procedure. Keywords: Aesthesia, General, Cardiac Surgical Procedures, Aortic Valve Stenosis, Aged.

Preoperative computer tomography evaluation in transcatheter aortic valve replacement (TAVI)

International Nuclear Information System (INIS)

Groudeva, V.; Stoynova, V.; Trendafilova, D.; Dzhorgova, Y.; Nachev, G.

2014-01-01

Transcatheter aortic valve replacement is rapidly emerging technique alternative to surgery in high risk patients. Imaging and especially computer tomography is important in preoperative assessment of the aortic ring and the prosthetic valve choice. The aim of this study is to share authors initial experience in CT assessment of the aortic ring prior to Transcatheter aortic valve replacement. 49 patients (mean age 76,55) underwent 320 rows MDCT (Acquilon One) prior TAVI. Protocol involved scanning from thoracic inlet to common femoral arteries. Aortic root size, aortic diameter at the level of coronary sinuses and the sinotubular junction and distance to coronary ostia were evaluated on a Vitrea work station. MDCT established maximal aortic ring diameter from 18 to 31 mm mean 25,04 mm while the lesser rate was from 16 to 21 mm. Accordingly positioned prostheses were in 34,75% No. 23, in 49% - No. 26 and in16,3% - No. 29. MDCT is crucial in aortic valve assessment prior to TAVI in experienced hands and multidisciplinary team. (authors) Key words: TRANSCATHETER AORTIC VALVE REPLACEMENT (TAVI). MDCT AORTIC VALVE ASSESSMENT

Transfemoral Aortic Valve Implantation with the New Edwards Sapien 3 Valve for Treatment of Severe Aortic Stenosis-Impact of Valve Size in a Single Center Experience.

Directory of Open Access Journals (Sweden)

Jochen Wöhrle

Full Text Available The third generation Edwards Sapien 3 (Edwards Lifesciences Inc., Irvine, California system was optimized to reduce residual aortic regurgitation and vascular complications.235 patients with severe symptomatic aortic stenosis were prospectively enrolled. Transcatheter aortic valve implantations (TAVI were performed without general anesthesia by transfemoral approach. Patients were followed for 30 days. Patients received 23mm (N = 77, 26mm (N = 91 or 29mm (N = 67 valve based on pre-procedural 256 multislice computer tomography. Mean oversizing did not differ between the 3 valves. There was no residual moderate or severe aortic regurgitation. Rate of mild aortic regurgitation and regurgitation index did not differ between groups. There was no switch to general anesthesia or conversion to surgery. Rate of major vascular complication was 3.0% with no difference between valve and delivery sheath sizes. Within 30 days rates of all cause mortality (2.6% and stroke (2.1% were low.In patients with severe aortic stenosis transfemoral TAVI with the Edwards Sapien 3 valve without general anesthesia was associated with a high rate of device success, no moderate or severe residual aortic regurgitation, low rates of major vascular complication, mortality and stroke within 30 days with no difference between the 3 valve sizes.ClinicalTrials.gov NCT02162069.

Analysis of the cylinder block tilting inertia moment and its effect on the performance of high-speed electro-hydrostatic actuator pumps of aircraft

Directory of Open Access Journals (Sweden)

Junhui ZHANG

2018-01-01

Full Text Available Electro-hydrostatic actuator (EHA pumps are usually characterized as high speed and small displacement. The tilting inertia moment on the cylinder block produced by the inertia forces of piston/slipper assemblies cannot be ignored when analyzing the cylinder block balance. A large tilting inertia moment will make the cylinder block tilt away from the valve plate, resulting in severe wear and significantly increased leakage. This paper presents an analytical expression for the tilting inertia moment on the cylinder block by means of vector analysis. In addition, a high-speed test rig was built up, and experiments on an EHA pump prototype were carried out at high speeds of up to 10,000 r/min. The predicted nature of the cylinder block tilt at high speeds corresponds closely to the witness marks on the dismantled EHA pump prototype. It is suggested that more attention should be given to the tilting inertia moment acting on the cylinder block of an EHA pump since both wear and leakage flow between the cylinder block and the valve plate are very much dependent on this tilting moment.

Heart valve surgery