WorldWideScience

Sample records for check valve leakage

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

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, R.; Harrell, J.

    1996-12-01

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

  2. Floating-disk parylene micro check valve

    OpenAIRE

    Chen, Po-Jui; Tai, Yu-Chong

    2008-01-01

    A novel micro check valve which has nearly ideal fluidic shunting behaviors is presented. Featuring a parylene-based floating disk, this surface-micromachined check valve ultimately realizes both zero forward cracking pressure and zero reverse leakage in fluidic operations. Two different floating disk designs have been implemented to demonstrate functionality of the microvalve. Experimental data of underwater testing successfully show that in-channel floating-disk valv...

  3. Miniaturized passive hydrogel check valve for hydrocephalus treatment.

    Science.gov (United States)

    Schwerdt, Helen N; Bristol, Ruth E; Junseok Chae

    2014-03-01

    Improvements in cerebrospinal fluid (CSF) draining techniques for treatment of hydrocephalus are urgently sought after to substitute for current CSF shunts that are plagued by high failure rates. The passive check valve aims to restore near natural CSF draining operations while mitigating possible failure mechanisms caused by finite leakage or low resilience that frequently constrain practical implementation of miniaturized valves. A simple hydrogel diaphragm structures core passive valve operations and enforce valve sealing properties to substantially lower reverse flow leakage. Experimental measurements demonstrate realization of targeted cracking pressures (PT ≈ 20-110 mmH2O) and operation at -800 <; ΔP <; 600 mmH2O without observable degradation or leakage.

  4. Check valve slam analysis in pumping station

    Science.gov (United States)

    Himr, D.; Habán, V.; Dokoupil, P.

    2016-03-01

    Pumping station supplies water for technological process. The check valve in the station was replaced with a new one. The regular test of black out discovered the high pressure pulsations accompanied with noticeable pipeline movement of discharge pipe. It was caused by late check valve closing, probably, when the back flow reached the highest possible velocity. This statement was supported with analysis of results of pressure measurement near the check valve and with a numerical simulation of the flow in the pipeline system.

  5. Check valve slam analysis in pumping station

    OpenAIRE

    Himr D.; Habán V.; Dokoupil P.

    2016-01-01

    Pumping station supplies water for technological process. The check valve in the station was replaced with a new one. The regular test of black out discovered the high pressure pulsations accompanied with noticeable pipeline movement of discharge pipe. It was caused by late check valve closing, probably, when the back flow reached the highest possible velocity. This statement was supported with analysis of results of pressure measurement near the check valve and with a numerical simulation of...

  6. Microbial Check Valve for Shuttle

    Science.gov (United States)

    Colombo, G. V.; Putnam, D. F.; Sauer, R. L.

    1978-01-01

    The Microbial Check Valve (MCV) is a device developed for the Space Shuttle that prevents the transfer of viable microorganisms within water systems. The device is essentially a bed of resin material, impregnated with iodine, that kills microorganisms on contact. It prevents the cross-contamination of microorganisms from a nonpotable system into the potable water system when these systems are interconnected. In this regard, the function of the device is similar to that of the 'air gap' found in conventional one-gravity systems. Basic design data are presented including pressure drop, scaling factors, sizing criteria, and the results of challenging the device with suspensions of seven microorganisms including aerobes, anaerobes and spore formers.

  7. Assessment of diagnostic methods for determining degradation of check valves

    International Nuclear Information System (INIS)

    The Oak Ridge National Laboratory (ORNL) has carried out a comprehensive aging assessment of check valves in support of the Nuclear Plant Aging Research (NPAR) program. This paper provides a summary of the ORNL check valve aging assessment with emphasis on the identification, evaluation, and application of check valve monitoring methods and techniques. Several check valve monitoring methods are described and compared. These methods include: acoustic emission monitoring, ultrasonic inspection, magnetic flux signature analysis (MFSA), external magnetics. These diagnostic technologies were shown to be useful in determining check valve condition (e.g., disc position, disc motion, and seat leakage), although none of the methods was by itself, successful in monitoring all three condition indicators. The combination of acoustic emission with either ultrasonics or one of the magnetic technologies, however, yields a monitoring system that succeeds in providing the sensitivity to detect all major check valve operating conditions. Other areas covered in the paper include descriptions of relevant regulatory issues, utility group activities, and interactions ORNL has had with outside organizations for the purpose of disseminating research results

  8. Advanced microbial check valve development

    Science.gov (United States)

    Colombo, G. V.; Greenley, D. R.

    1980-01-01

    A flight certified assembly identified as a Microbial Check Valve (MCV) was developed and tested. The MCV is a canister packed with an iodinated anionic exchange resin. The device is used to destroy organisms in a water stream as the water passes through the device. The device is equally effective for fluid flow in either direction and its primary method of organism removal is killing rather than filtering. The MCV was successfully developed for the space shuttle to: disinfect fuel cell water; and prevent back contamination of the stored potable water supply. One version of the device consists of a high residual iodinated resin bed that imparts approximately 2 ppm of iodine to the fuel cell water as it flows to the potable water tanks. A second version of the device consists of a low residual iodinated resin bed. One of these low residual beds is located at each use port in the potable water system for the dual purpose of removing some iodine from the potable water as it is dispensed and also to prevent back contamination of the potable supply.

  9. Improved microbial-check-valve resins

    Science.gov (United States)

    Colombo, G. V.; Putnam, D. F.

    1980-01-01

    Improved microbial-check-valve resins have been tested for their microbicidal effectiveness and long-term stability. Resins give more-stable iodine concentrations than previous preparations and do not impart objectionable odor or taste to treated water. Microbial check valve is small cylindrical device, packed with iodide-saturated resin, that is installed in water line where contamination by micro-organisms is to be prevented. Prototype microbial check valve was tested for stability and performance under harsh environmental conditions. Effectiveness was 100 percent at 35 deg, 70 deg, and 160 deg F (2 deg, 21 deg, and 71 deg C).

  10. Check valve slam analysis in pumping station

    Directory of Open Access Journals (Sweden)

    Himr D.

    2016-01-01

    Full Text Available Pumping station supplies water for technological process. The check valve in the station was replaced with a new one. The regular test of black out discovered the high pressure pulsations accompanied with noticeable pipeline movement of discharge pipe. It was caused by late check valve closing, probably, when the back flow reached the highest possible velocity. This statement was supported with analysis of results of pressure measurement near the check valve and with a numerical simulation of the flow in the pipeline system.

  11. Action plans for motor-operated valves and check valves

    International Nuclear Information System (INIS)

    The proper performance of motor-operated valves (MOVs) and check valves is necessary for the safety operation of a nuclear power plant. Problems have been experienced, however, with these valves for many years. Currently, the US Nuclear Regulatory Commission (NRC) and the nuclear industry have a number of activities under way to provide assurance that MOVs and check valves will successfully perform their safety functions when needed. The Mechanical Engineering Branch (EMEB) of the NRC Office of Nuclear Reactor Regulation has been assigned the responsibility of coordinating NRC activities and monitoring industry activities regarding MOVs and check valves. To meet this responsibility, EMEB has prepared action plans to provide assurance of the proper performance of these valves. Among the staff activities described in the action plans is the consideration of the need to revise the regulations to clarify the inservice testing (IST) requirements for these valves. The need for regulatory guidance for the development of acceptable IST programs, as well as for other licensee activities relating to the performance of MOVs and check valves, will also be evaluated. In addition, NRC personnel will have to verify, in a consistent manner, implementation of licensee commitments in response to NRC generic letters and bulletins. Another important aspect of the action plans is the provision for the NRC staff to provide assistance, where appropriate, to the industry in its efforts to address MOV and check valve issues. Finally, the action plans include a tentative schedule for accomplishing the described staff activities

  12. Glovebox pressure relief and check valve

    Energy Technology Data Exchange (ETDEWEB)

    Blaedel, K.L.

    1986-03-17

    This device is a combined pressure relief valve and check valve providing overpressure protection and preventing back flow into an inert atmosphere enclosure. The pressure relief is embodied by a submerged vent line in a mercury reservior, the releif pressure being a function of the submerged depth. The pressure relief can be vented into an exhaust system and the relieving pressure is only slightly influenced by the varying pressure in the exhaust system. The check valve is embodied by a ball which floats on the mercury column and contacts a seat whenever vacuum exists within the glovebox enclosure. Alternatively, the check valve is embodied by a vertical column of mercury, the maximum back pressure being a function of the height of the column of mercury.

  13. 42 CFR 84.123 - Exhalation valve leakage test.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Exhalation valve leakage test. 84.123 Section 84.123 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY....123 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be subjected to...

  14. Valve packing leakage monitoring device

    International Nuclear Information System (INIS)

    A device for monitoring leakage of fluid across a seal in a component connected to a pressurized fluid system including a housing having a chamber with an inlet for receiving fluid leaking across the seal and an outlet. A positioning means is connected to an orifice plug so as to move the plug for permitting the fluid to be discharged through the orifice at the same rate at which it enters the first chamber and means for detecting the movement of the plug is provided to produce and output signal corresponding to the distance moved by the plug and thereby indicate flow rate. The positioning means compromise a piston attached to the plug by a hollow tube and springs, which at low flow rates locate the piston. When flow increases sufficiently pressure increases and urges the piston upwards. A magnetic portion of tube actuates a succession of proximity switches to indicate flow rate. (author)

  15. Neural Network Approach to Automated Condition Classification of a Check Valve by Acoustic Emission Signals

    International Nuclear Information System (INIS)

    This paper presents new techniques under development for monitoring the health and vibration of the active components in nuclear power plants, The purpose of this study is to develop an automated system for condition classification of a check valve one of the components being used extensively in a safety system of a nuclear power plant. Acoustic emission testing for a check valve under controlled flow loop conditions was performed to detect and evaluate disc movement for valve failure such as wear and leakage due to foreign object interference in a check valve, It is clearly demonstrated that the evaluation of different types of failure types such as disc wear and check valve leakage were successful by systematically analyzing the characteristics of various AE parameters, It is also shown that the leak size can be determined with an artificial neural network

  16. Non intrusive check valve diagnostics at Bruce A

    Energy Technology Data Exchange (ETDEWEB)

    Marsch, S.P. [Ontario Hydro, Bruce Nuclear Generating Station A, Tiverton, ON (Canada)

    1997-07-01

    Bruce A purchased non intrusive check valve diagnostic equipment in 1995 to ensure operability and availability of critical check valves in the Station. Diagnostics can be used to locate and monitor check valve degradation modes. Bruce A initiated a pilot program targeting check valves with flow through them and ones that completed open or close cycles. Approaches to determine how to confirm operability of passive check valves using non intrusive techniques were explored. A sample population of seventy-three check valves was selected to run the pilot program on prior to complete implementation. The pilot program produced some significant results and some inconclusive results. The program revealed a major finding that check valve performance modeling is required to ensure continuous operability of check valves. (author)

  17. 42 CFR 84.137 - Inhalation and exhalation valves; check valves; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Inhalation and exhalation valves; check valves... PROTECTIVE DEVICES Supplied-Air Respirators § 84.137 Inhalation and exhalation valves; check valves; minimum requirements. (a) Inhalation and exhalation valves shall be provided where necessary and protected...

  18. Development of a stainless steel check valve for cryogenic applications

    NARCIS (Netherlands)

    Veenstra, T.T.; Venhorst, G.C.F.; Burger, J.F.; Holland, H.J.; Brake, ter H.J.M.; Sirbi, A.; Rogalla, H.

    2007-01-01

    This paper describes the development of a check valve for use in a sorption compressor that will drive a 10 mW 4.5 K Joule–Thomson cryocooler. For the check valve extremely low backflow rates are tolerable at an operating temperature of the valve of 50 K. To fulfill these requirements, the sealing m

  19. Water system microbial check valve development

    Science.gov (United States)

    Colombo, G. V.; Greenley, D. R.; Putnam, D. F.

    1978-01-01

    Development work on a device for the Space Shuttle that will prevent the transfer of viable microorganisms within water systems is described. The device serves as a check valve in that it prevents the transfer or cross-contamination of microorganisms from a nonpotable system into a potable water system when these systems are interconnected. In this regard, the function of the device is similar to that of the air gap found in conventional one gravity systems. The device is essentially a bed of resin material impregnated with iodine. Basic design data for a variety of flow and temperature conditions are presented, together with results of challenging the beds with suspensions of seven microorganisms including aerobes, anaerobes, and spore formers.

  20. Review and analysis of check valve failure data

    Science.gov (United States)

    Todd, M. D.; Casada, D. A.

    Check valve operating problems in recent years have resulted in significant operating transients, increased cost and decreased system availability. There has been, in response, additional attention given to check valves by utilities, as well as the US Nuclear Regulatory Commission and the American Society of Mechanical Engineers Operation and Maintenance Committee. All these organizations have the fundamental goal of ensuring reliable operation of check valves. A key ingredient to an engineering-oriented reliability improvement effort is a thorough understanding of relevant historical experience. Oak Ridge National Laboratory is currently conducting a detailed review of historical failure data available through the Institute of Nuclear Power Operation's Nuclear Plant Reliability Data System. The focus of the review is on check valve failures that have involved significant degradation of the valve internal parts. A variety of parameters are being considered during the review, including size, age, system of service, method of failure discovery, the affected valve parts, attributed causes, and corrective actions.

  1. A study on the condition monitoring of check valve at nuclear power plants using the acoustic emission and a neural network technique

    International Nuclear Information System (INIS)

    The analysis of Acoustic Emission (AE) signals produced during object leakage is promising for condition monitoring of the components. In this study, an advanced condition monitoring technique based on acoustic emission detection and artificial neural networks was applied to a check valve, one of the components being used extensively in a safety system of a nuclear power plant. AE testing for a check valve under controlled flow loop conditions was performed to detect and evaluate disk movement for valve degradation such as wear and leakage due to foreign object interference in a check valve. It is clearly demonstrated that the evaluation of different types of failure modes such as disk wear and check valve leakage were successful by systematically analyzing the characteristics of various AE parameters. It is also shown that the leak size can be determined with an artificial neural network

  2. Experimental and Analytical Study on the Lift Check Valve

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. H.; Song, C. S.; Kim, H. S.; Hong, S. C. [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of); Lee, W. H. [Samshin Limited Co., Chonan (Korea, Republic of)

    2009-10-15

    In general, the check valve mounted on the flow line is used for the purpose of protecting the pump and the related facility, making the flow path, and maintaining the pressure boundary during the operation mode change in steam power plant and nuclear power plant. Fig. 1 shows the example of check valve in nuclear power plant. Especially, the check valve mounted on safety feed system and nuclear safety system is operated to open state and has a role of acquiring enough fluid such as safety feed and auxiliary feed water in the Design Basis Accident. And the check valve is operated with enough sealing and with protecting steam hammer in normal operational mode. For this purpose, the check valve can be open easily and be maintained in the open state in case of small flow velocity. In this research, the experimental and analytical study on the check vale was performed. The flow coefficient and closure time were compared between the experimental and the analytical result by numerical simulation. The validation of the analytical method was performed.

  3. Defining indicators to motorize block valves aiming to reduce potential leakage applied to OSBRA pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Pires, L.F.G. [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil); Sousa, A.G.; Castro, N.C.; Spagnolo, R. [Petrobras Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    The discussion about motorizing block valves is a constant point being brought up when it is intended to control or reduce the amount of liquid leaking in the event of a pipe rupture. During the pipeline's project stage the installation of blocking valves along the pipeline must be taken into consideration to meet the operation and maintenance requirements as well as to reduce the potential amounts of volume being leaked. In existing pipelines, the main concern is the definition of which valves are candidates to be motorized. In both situations criteria should be established to define this choice. A math algorithm was developed to define the potential leakage due to gravity along the pipeline profile where the influence of a valve over another is verified, as well as the contribution of the check valves existing in the pipeline. The present work defines a parameter based on the extension protected by the valve and the reduction of the potential leakage. This parameter is then fed to a worksheet where the efficiency indicators are calculated to each valve eligible to be motorized. It also takes into consideration factors relative to the valve location, such as the environmental sensitivity, risk assessment, social diagnosis and device's proximity to contingency resources. Finally, after considering all the above aspects, it's possible to come up with a final classification, recommending specific valves to be prioritized on an eventual process of motorization adequacies. This methodology was applied, experimentally on a pipe segment of TRANSPETRO's Sao Paulo-Brasilia pipeline - OSBRA , where it proved to be an important technological and management tool. (author)

  4. The use of check valve performance data to support new concepts (probabilistic risk assessment, condition monitoring) for check valve program

    Energy Technology Data Exchange (ETDEWEB)

    Hart, K.A.; Gower, D.

    1996-12-01

    The concept of developing an integrated check valve database based on the Nuclear Power Reliability Data System (NPRDS) data was presented at the last Symposium. The Nuclear Industry Check Valve Group (NIC), working in cooperation with the Oak Ridge National Laboratory (ORNL), has completed an operational database of check valve performance from 1984 to the present. NIC has committed to the nuclear industry to periodically update the data and maintain this information accessible. As the new concepts of probabilistic risk analysis and condition monitoring are integrated into the American Society of Mechanical Engineers (ASME) Code, a critical element will be performance data. From check valve performance data, feasible failure modes and rates can be established. When a failure rate or frequency of failures can be established based on a significant enough population (sampling), a more solid foundation for focusing resources and determining appropriate frequencies and testing can be determined. The presentation will give the updated status of the NIC Check Valve Performance Database covering (1) methodology used to combine the original ORNL data; (2) process/controls established for continuing update and refinement of the data; (3) discussion of how this data is being utilized by (a) OM-22 for condition monitoring, and (b) risk-based inservice testing work of Westinghouse Owners` Group; and (4) results/trends of data evaluations. At the 1994 Symposium, ORNL provided an update as of 1991 to their original work of 1984 -1990 which they had performed to characterize check valve degradations and failures in the nuclear industry. These characterizations will be updated to 1995 and additional reviews provided to give insight into the current condition and trends of check valve performance.

  5. Development of a stainless steel check valve for cryogenic applications

    Science.gov (United States)

    Veenstra, T. T.; Venhorst, G. C. F.; Burger, J. F.; Holland, H. J.; ter Brake, H. J. M.; Sirbi, A.; Rogalla, H.

    2007-02-01

    This paper describes the development of a check valve for use in a sorption compressor that will drive a 10 mW 4.5 K Joule-Thomson cryocooler. For the check valve extremely low backflow rates are tolerable at an operating temperature of the valve of 50 K. To fulfill these requirements, the sealing mechanism of the valve is based on a full metal to metal contact. In order to obtain sufficiently low leak rates, both parts were machined to a surface flatness in the order of 100 nm. In addition, the closing plate (boss) of the valve deforms (bends) slightly under pressure, forming itself to the opposite valve seat and thus reducing the gap between these parts. The measured leak flow at 50 K was 1.6 μg/s helium @ 16 bar pressure difference, which is well below the aim of 3 μg/s. The valve was subjected to an accelerated lifetime test of 300,000 cycles. It was observed that the leak flow through the valve during this test steadily decreased to a level of 0.15 μg/s after 100,000 cycles.

  6. SU8 diaphragm micropump with monolithically integrated cantilever check valves.

    Science.gov (United States)

    Ezkerra, Aitor; Fernández, Luis José; Mayora, Kepa; Ruano-López, Jesús Miguel

    2011-10-01

    This paper presents a SU8 unidirectional diaphragm micropump with embedded out-of-plane cantilever check valves. The device represents a reliable and low-cost solution for integration of microfluidic control in lab-on-a-chip devices. Its planar architecture allows monolithic definition of its components in a single step and potential integration with previously reported PCR, electrophoresis and flow-sensing SU8 microdevices. Pneumatic actuation is applied on a PDMS diaphragm, which is bonded to the SU8 body at wafer level, further enhancing its integration and mass production capabilities. The cantilever check valves move synchronously with the diaphragm, feature fast response (10ms), low dead volume (86nl) and a 94% flow blockage up to 300kPa. The micropump achieves a maximum flow rate of 177 μl min(-1) at 6 Hz and 200 kPa with an effective area of 10 mm(2). The device is reliable, self-priming and tolerant to particles and big bubbles. To the knowledge of the authors, this is the first micropump in SU8 with monolithically integrated cantilever check valves. PMID:21853192

  7. PILOT LEAKAGE'S INFLUENCES ON THE PERFORMANCES OF EXTRA HIGH PRESSURE PROPORTIONAL PNEUMATIC VALVE

    Institute of Scientific and Technical Information of China (English)

    Chen Yize; Wang Xuanyin; Xu Zhipeng; Tao Guoliang

    2005-01-01

    A mathematic model is built up to analyze the influences of a pilot valve's leakage on the performances of pneumatic pressure proportional valve, and the performances are simulated by using MATLAB. The results indicate that using slide pilot valve in the valve system is feasible, but the leakage's influences can not be neglected, especially it may induce instability in a low output pressure situation. A pilot valve using too large throttle window will cause the valve oscillate. To improve the working condition of pilot valve, a method adopting different widths of two throttle window is proposed. According to our simulation, this method balances the pressure drop between the two stage throttle ports, and reduces the influences of pilot valve's leakage.

  8. Mitral Valve Replacement with Half-and-Half Technique for Recurrent Mitral Paravalvular Leakage.

    Science.gov (United States)

    Morisaki, Akimasa; Kato, Yasuyuki; Takahashi, Yosuke; Shibata, Toshihiko

    2015-05-01

    Reoperation for paravalvular leakage can cause recurrent paravalvular leakage through severe damage to the mitral annulus. Previously, mitral valve replacement using a half-and-half technique for extensive mitral annular calcification was reported; here, application of the technique to treat recurrent paravalvular leakage is described. A 78-year-old male with three prior mitral valve replacements developed recurrent paravalvular leakage, for which he had undergone his third mitral valve replacement at the age of 69 years. On this occasion, a mechanical valve with circumferential equine pericardial patch reinforcement of the annulus had been used. Five years later, the patient developed hemolytic anemia and congestive heart failure due to recurrent paravalvular leakage. Intraoperatively, broad dehiscence was seen between the prosthetic valve and mitral annulus at two sites, the anterior and posterior commissures, without infection. A fourth mitral valve replacement was performed with a St. Jude Medical valve, using a half-and-half technique. This entailed the use of non-everting mattress sutures on the anterior half of the annulus, and everting mattress sutures on the left atrial wall around the posterior half of the annulus. Extensive annular defects required reinforcement of the posterior mitral annulus with a bovine pericardial patch. Postoperative echocardiography showed no paravalvular leakage. The half-and-half technique may be useful in treating recurrent paravalvular leakage of the mitral valve. PMID:26901904

  9. Regenerable Microbial Check Valve - Life cycle tests results

    Science.gov (United States)

    Atwater, James E.; Wheeler, Richard R., Jr.; Olivadoti, J. T.; Sauer, Richard L.; Flanagan, David T.

    1992-01-01

    Life cycle regeneration testing of the Microbial Check Valve (MCV) that is used on the Shuttle Orbiter to provide microbial control of potable water is currently in progress. Four beds are being challenged with simulated reclaimed waters and repeatedly regenerated. Preliminary results indicate that contaminant systems exhibit unique regeneration periodicities. Cyclic throughput diminishes with increasing cumulative flow. It is considered to be feasible to design a regenerable MCV system which will function without human intervention and with minimal resupply penalty for the 30 year life of the Space Station.

  10. The Structure of Wheel Check Valve Influence on Air Block Phenomenon of Piezoelectric Micro-Pump

    OpenAIRE

    Song Chen; Yong Liu; Yanhu Shen; Jiantao Wang; Zhigang Yang

    2015-01-01

    To improve the stability and reliability of the piezoelectric micro-pump, the cause of air block phenomenon is analyzed on the structure of wheel check valve. During the movement of the bubble in the micro-channel, pressure drop occurs, the main factor which influences the bubble going through is opening height of the wheel check valve. Five groups of wheel check valves with different structures are used to test the wheel check valve opening height and air block probability. The experiment re...

  11. Mitigating check valve slamming and subsequentwater hammer events for PPFS using MOC

    Institute of Scientific and Technical Information of China (English)

    TIAN Wenxi; SU Guanghui; WANG Gaopeng; QIU Suizheng; XIAO Zejun

    2009-01-01

    The method of characteristic (MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System (PPFS) during the alternate startup process. The motion of check valve disc was simulated using inertial valve model. Transient parameters including the pressure oscillation, local flow velocity and slamming of the check valve disc etc. have been obtained. The results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel pumps. The induced maximum pressure vibration amplitude is up to 5.0 MPa. The scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water hammer. It has been numerically approved to be an effective approach.

  12. A Study on the Leakage Evaluation for Power Plant Valve Using Infrared Thermography Method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Guk [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    2010-04-15

    This study was conducted to estimate the feasibility using thermal image measurement that is applicable to internal leak diagnosis for the power plant valve. Abnormal heating of valve surface associated with high temperature steam f10w toward valve outlet side in the condition of low temperature is a primary indicator of leakage problems in high temperature and pressure valves. Thermal imaging enables to see the invisible thermal radiation that may portend impending damage before their condition becomes critical. When steam flow in valve outlet side in the condition of low temperature is converted into heat transmitted through the valve body due to the internal leakage in valve. The existence of abnormally increasable leakage rate in the valve will result in abnormally high levels of heat to be generated that can be quickly identified with a thermal image avoiding energy loss or damage of valve component. From the experimental results, it was suggested that the thermal image measurement could be an effective way to precisely diagnose and evaluate internal leak situation of valve

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-01

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

  15. The Structure of Wheel Check Valve Influence on Air Block Phenomenon of Piezoelectric Micro-Pump

    Directory of Open Access Journals (Sweden)

    Song Chen

    2015-11-01

    Full Text Available To improve the stability and reliability of the piezoelectric micro-pump, the cause of air block phenomenon is analyzed on the structure of wheel check valve. During the movement of the bubble in the micro-channel, pressure drop occurs, the main factor which influences the bubble going through is opening height of the wheel check valve. Five groups of wheel check valves with different structures are used to test the wheel check valve opening height and air block probability. The experiment results show that reducing the wheel check valve thickness or diameter ratio can both increase the wheel check valve opening height, and decrease the air block probability. Through experiment, the optimum combination of the wheel check valve structure is obtained within the samples: as the thickness is 0.02 mm, the diameter ratio is 1.2, the wheel check valve opening height gets 252 µm, and within the given bubble volume, the air block probability is less than 2%.

  16. Model based feasibility study on bidirectional check valves in wave energy converters

    DEFF Research Database (Denmark)

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

    2014-01-01

    /Off and bidirectional check valves. Based on the analysis it is found that the energy production may be slightly improved by using bidirectional check valves as compared to on/off valves, due to a decrease in switching losses. Furthermore a reduction in high flow peaks are realised. The downside being increased...... valves in wave energy converters to improve the system efficiency. A single float arm of the Wavestar wave energy converter is modelled including the power take-off (PTO) system. The primary stage of the utilised PTO-system is a discrete fluid power force system consisting of a multi-chamber cylinder...... and multiple common pressure lines. The valve manifold, employed in the discrete PTO system and conventionally equipped with On/Off valves, is instead considered fitted with bidirectional check valves. The energy output from the primary stage is compared for PTO systems occupying respectively On...

  17. Leakage Test Criteria for Subsea Christmas Tree Valves

    OpenAIRE

    Alstad, Charlotte

    2011-01-01

    This Master`s Thesis deal with integrity and barrier philosophy. A special focus has been on internal leakage through barrier elements. There is an increasing discussion about what a primary and secondary barrier is, how many barriers there should be, their permitted internal leakage acceptance criteria and their integrity. Subsea Christmas tree (XMT) is considered as a pressure barrier element in subsea production systems. Rules and regulations require frequent leakage testing of subsea XMT ...

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    Discrete fluid power force systems consisting of a multichamber cylinder, a witching manifold and common pressure lines have been proposed as a technology for increasing the efficiency of the power take off system in ocean wave energy converters. However the force shifting of these discrete systems...... introduces large switching losses, especially when large pressure difference is present across the valves in the manifold. The current paper therefore focus on designing a bidirectional check valve for use in the switching manifold of the discrete force systems. The use of the bidirectional check valve...... enables passive force switching under minimal pressure difference, hence minimal energy loss. The bidirectional check valve is designed with a rated flow in the range of 1000L/min@5bar. The flow direction of the bidirectional check valve is set by the setting the pilot pressure. This paper presents...

  19. A novel micropump with fixed-geometry valves and low leakage flow

    Science.gov (United States)

    Hwang, Il-Han; An, Jae-Yong; Ko, Kwang-Hee; Shin, Sang-Mo; Lee, Jong-Hyun

    2007-08-01

    A novel micropump with fixed-geometry valves was designed and tested with a leakage barrier to reduce leakage flow. Conventional micropumps with fixed-geometry valves have achieved net positive fluid flow from different fluid resistances in diffuser/nozzle channels. However, those micropumps are susceptible to leakage flow even at low pressure differences between the inlet and the outlet because the channels remain normally open state when the pumps are not in operation. Therefore, a leakage barrier in the chamber was designed to reduce leakage flow without interfering with the net positive fluid flow of the diffuser/nozzle channels. The diffuser/nozzle channels, the chamber and the leakage barrier were fabricated on the silicon substrate by KOH etching and the silicon substrate was anodically bonded with a Pyrex glass plate. A PZT disk was bonded on the glass plate by epoxy and was actuated to oscillate the glass diaphragm for flow generation. When the micropump is not operating, the leakage barrier removes most of the gap between the glass plate and the bottom of the chamber. It was experimentally confirmed that the leakage barrier reduced the leakage flow by 96% compared to the case of no leakage barrier at a pressure difference of -400 Pa. Moreover, by applying the holding dc voltage to the PZT disk, a smaller gap can be obtained reducing the leakage flow further down to 0.043 µL min-1 at a holding dc voltage of 100 V. The maximum flow rate was 3.9 µL min-1 at a peak-to-peak driving voltage of 150 V at 20 Hz with a maximum back pressure of around 800 Pa. The approximate device size was 18 × 25 mm2.

  20. Pump, and earth-testable spacecraft capillary heat transport loop using augmentation pump and check valves

    Science.gov (United States)

    Baker, David (Inventor)

    1998-01-01

    A spacecraft includes heat-generating payload equipment, and a heat transport system with a cold plate thermally coupled to the equipment and a capillary-wick evaporator, for evaporating coolant liquid to cool the equipment. The coolant vapor is coupled to a condenser and in a loop back to the evaporator. A heated coolant reservoir is coupled to the loop for pressure control. If the wick is not wetted, heat transfer will not begin or continue. A pair of check valves are coupled in the loop, and the heater is cycled for augmentation pumping of coolant to and from the reservoir. This augmentation pumping, in conjunction with the check valves, wets the wick. The wick liquid storage capacity allows the augmentation pump to provide continuous pulsed liquid flow to assure continuous vapor transport and a continuously operating heat transport system. The check valves are of the ball type to assure maximum reliability. However, any type of check valve can be used, including designs which are preloaded in the closed position. The check valve may use any ball or poppet material which resists corrosion. For optimum performance during testing on Earth, the ball or poppet would have neutral buoyancy or be configured in a closed position when the heat transport system is not operating. The ball may be porous to allow passage of coolant vapor.

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

    Science.gov (United States)

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

    2014-11-01

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

  2. Check valve slam caused by air intrusion in emergency cooling water system

    International Nuclear Information System (INIS)

    Waterhammer pressures were experienced during periodic starting of Residual Heat Removal (RHR) pumps at a nuclear plant. Prior to an analytical investigation careful analysis performed by plant engineers indicated that the spring effect of entrapped air in a heat exchanger resulted in water hammer due to check valve slam following flow reversal. In order to determine in more detail the values of pertinent parameters controlling this water hammer a hydraulic transient analysis was performed of the RHR piping system, including essential elements such as the pump, check valve, and heat exchanger. Using characteristic torque and pressure loss curves the motion of the check valve was determined. By comparing output of the water hammer analysis with site recordings of pump discharge pressure the computer model was calibrated, allowing for a realistic estimate of the quantity of entrapped air in the heat exchanger. (author)

  3. A self-priming, high performance, check valve diaphragm micropump made from SOI wafers

    Science.gov (United States)

    Kang, Jianke; Mantese, Joseph V.; Auner, Gregory W.

    2008-12-01

    In this paper, we describe a self-priming high performance piezoelectrically actuated check valve diaphragm micropump. The micropump was fabricated from three wafers: two silicon-on-insulator (SOI) wafers and one silicon wafer. A process named 'SOI/SOI wafer bonding and etching back followed by a second wafer bonding' was developed in order to make the core components of this device which included an inlet check valve, an outlet check valve, a diaphragm and a chamber. The movable structures of this device, i.e. the check valves and the diaphragm, were fabricated from the device layers of the two bonded SOI wafers. Taking advantages of SOI wafer technology and etch-stop layers, the vertical parameters of the movable structures were precisely controlled in fabrication. The micropump was self-priming without any pre-filling process. The pumping rate of the micropump was linearly adjustable from 0 to 650l µm min-1 by adjusting frequency. The maximum pumping rate was 860 µl min-1 and the maximum pumping pressure was approximately 10.5 psi. The power consumption of the device was less than 1.2 mW.

  4. A self-priming, high performance, check valve diaphragm micropump made from SOI wafers

    International Nuclear Information System (INIS)

    In this paper, we describe a self-priming high performance piezoelectrically actuated check valve diaphragm micropump. The micropump was fabricated from three wafers: two silicon-on-insulator (SOI) wafers and one silicon wafer. A process named 'SOI/SOI wafer bonding and etching back followed by a second wafer bonding' was developed in order to make the core components of this device which included an inlet check valve, an outlet check valve, a diaphragm and a chamber. The movable structures of this device, i.e. the check valves and the diaphragm, were fabricated from the device layers of the two bonded SOI wafers. Taking advantages of SOI wafer technology and etch-stop layers, the vertical parameters of the movable structures were precisely controlled in fabrication. The micropump was self-priming without any pre-filling process. The pumping rate of the micropump was linearly adjustable from 0 to 650l µm min−1 by adjusting frequency. The maximum pumping rate was 860 µl min−1 and the maximum pumping pressure was approximately 10.5 psi. The power consumption of the device was less than 1.2 mW

  5. Regulatory analysis for the resolution of generic issue C---8, main steam isolation valve leakage and LCS [leakage control system] failure

    International Nuclear Information System (INIS)

    Generic Issue C-8 deals with staff concerns about public risk because of the incidence of leak test failures reported for main steam isolation valves (MSIVs) at boiling water reactors and the limitations of the leakage control systems (LCSs) for mitigating the consequences of leakage from these valves. If the MSIV leakage is greatly in excess of the allowable value in the technical specifications, the LCS would be unavailable because of design limitations. The issue was initiated in 1983 to assess (1) the causes of MSIV leakage failures, (2) the effectiveness of the LCS and alternative mitigation paths, and (3) the need for additional regulatory action to reduce public risk. This report presents the regulatory analysis for Generic Issue C-8 and concludes that no new regulatory requirements are warranted

  6. 49 CFR Appendix B to Part 180 - Acceptable Internal Self-closing Stop Valve Leakage Tests for Cargo Tanks Transporting Liquefied...

    Science.gov (United States)

    2010-10-01

    ... leakage testing, leakage is defined as any leakage through the internal self-closing valve or to the... flow is established, the operator closes the internal self-closing stop valve and monitors the meter... meter as a flow measurement indicator. The test is initiated by starting the delivery process...

  7. Modeling of feed water check valves using RELAP5; Modellierung von Speisewasserrueckschlagventilen in RELAP5

    Energy Technology Data Exchange (ETDEWEB)

    Ben Said, Nader; Bregulla, Wolfgang; Kalk, Andreas [Westinghouse Electric Germany GmbH, Mannheim (Germany)

    2009-07-01

    Westinghouse Electric Germany GmbH has developed fluid dynamic models for medium-actuated armatures using the thermal hydraulic code RELAP5 in order to reach a more realistic description of the armature behavior including fluid-structure interactions in case of transient flow conditions in piping systems. The contribution is concerned with the modeling of damped check valves. The model allows the description of the behavior during opening and closure of a check armature. The calculated results show good agreement with the available measured data.

  8. Development of a check valve for two-stage pellet injectors

    International Nuclear Information System (INIS)

    The two-stage light gas gun is presently the most suitable method for injecting solid deuterium pellets at velocities in excess of 2000 m/s. However, the use of this technique in plasma machines presents some drawbacks: (1) the relatively large mass of propellant, which is of the same order of the pellet mass; (2) the shape of the pressure pulse, which does not provide an optimum acceleration, unless the pellet is forced in the barrel, providing a sufficient breakout pressure. These problems can be solved completely or in part, by interposing between the pump tube and the barrel a check valve with a suitable opening pressure. In this work a check valve developed at CNPM is described and experimental results are reported

  9. Dual Check Valve and Method of Controlling Flow Through the Same

    Science.gov (United States)

    Corallo, Roger (Inventor)

    2016-01-01

    A dual check valve includes, a housing having a cavity fluidically connecting three ports, a movable member movably engaged within the cavity from at least a first position occluding a first port of the three ports, a second position occluding a second port of the three ports, and a third position allowing flow between both the first port, the second port and a third port of the three ports.

  10. Polymeric check valve with an elevated pedestal for precise cracking pressure in a glaucoma drainage device.

    Science.gov (United States)

    Park, Chang-Ju; Yang, Dong-Seong; Cha, Jung-Joon; Lee, Jong-Hyun

    2016-02-01

    This paper presents the design, fabrication, and characterization of a polymeric micro check valve for a glaucoma drainage device (GDD) featuring the precise regulation of intraocular pressure (IOP) and effective aqueous humor turnover (AHT). The pedestal, slightly elevated by selective coating of a parylene C film, induces pre-stress in the thin valve membrane, which enhances the predictability of the cracking pressure of the GDD. The proposed GDD comprises a cannula and a normally closed polymeric micro check valve, which are made of PDMS, a biocompatible polymer, with three layers: top (cover), intermediate (thin valve membrane), and bottom (base plate). A feedback channel, located between the top and intermediate layers, prevents reverse flow by feeding the pressure of the outlet channel back to the thin valve membrane. To achieve a precise cracking pressure and sufficient drainage of humor for humans, the thicknesses of the valve membrane and parylene C film are designed to be 58 μm and 1 μm, respectively, which are confirmed using a COMSOL simulation. The experimental results show that the cracking pressure of the fabricated GDD lies within the range of normal IOP (1.33-2.67 kPa). The forward flow rate (drainage rate), 4.3 ± 0.9 μL/min at 2.5 kPa, is adequate to accommodate the rate of AHT in a normal human eye (2.4 ± 0.6 μL/min). The reverse flow was not observed when a hydrostatic pressure of up to 4 kPa was applied to the outlet and the feedback channel. PMID:26864969

  11. An Experimental Study of Emission and Combustion Characteristics of Marine Diesel Engine in Case of Cylinder Valves Leakage

    Directory of Open Access Journals (Sweden)

    Kowalski Jerzy

    2015-09-01

    Full Text Available Presented paper shows the results of the laboratory tests on the relationship between throttling of both air intake duct and exhaust gas duct and a gaseous emission from the marine engine. The object of research is a laboratory, four-stroke, DI diesel engine, operated at loads from 50 kW to 250 kW at a constant speed equal to 750 rpm. During the laboratory tests over 50 parameters of the engine were measured with its technical condition recognized as a „working properly” and with simulated leakage of both air intake valve and exhaust gas valve on the second cylinder. The results of this laboratory research confirm that the leakage of cylinder valves causes no significant changes of the thermodynamic parameters of the engine. Simulated leakages through the inlet and exhaust valve caused a significant increase in fuel consumption of the engine. Valve leakages cause an increase of the exhaust gas temperature behind the cylinder with leakage and behind other cylinders. The exhaust gas temperature increase is relatively small and clearly visible only at low loads of the engine. The increase of the temperature and pressure of the charging air behind the intercooler were observed too. Charging air temperature is significantly higher during the engine operation with inlet valve leakage. The study results show significant increases of the CO, NOx and CO2 emission for all the mentioned malfunctions. The conclusion is that the results of measurements of the composition of the exhaust gas may contain valuable diagnostic information about the technical condition of the air intake duct and the exhaust gas duct of the marine engine.

  12. 3D Printed Unibody Lab-on-a-Chip: Features Survey and Check-Valves Integration

    Directory of Open Access Journals (Sweden)

    Germán Comina

    2015-04-01

    Full Text Available The unibody lab-on-a-chip (ULOC concept entails a fast and affordable micro-prototyping system built around a single monolithic 3D printed element (unibody. A consumer-grade stereo lithography (SL 3D printer can configure ULOCs with different forms of sample delivery, transport, handling and readout, while minimizing material costs and fabrication time. ULOC centralizes all complex fabrication procedures and replaces the need for clean room resources, delivering prototypes for less than 1 US$, which can be printed in 10 min and ready for testing in less than 30 min. Recent examples of ULOC integration of transport, chemical sensing for optical readout and flow mixing capabilities are discussed, as well as the integration of the first check-valves for ULOC devices. ULOC valves are strictly unidirectional up to 100 psi, show an exponential forward flow behavior up to 70 psi and can be entirely fabricated with the ULOC approach.

  13. The seat test of axial flow check valves%轴流式止回阀的密封试验

    Institute of Scientific and Technical Information of China (English)

    彭林; 宋忠荣; 刘建峰; 张绍华; 陶国庆

    2012-01-01

    Analyses the structure and properties of axial flow check valves, and introduces the methods for seat test of axial flow check valves, the design and construction scheme of test system, and verifies the properties of the test system with the simulation conditions.%分析了轴流式止回阀的结构与性能特点,介绍了轴流式止回阀的密封试验方法、试验系统的设计与建设,并结合输送流体工况对试验系统的效果进行了验证。

  14. Failure investigation of type 410 stainless steel retaining block studs of swing check valves in pressurized water reactors

    International Nuclear Information System (INIS)

    Retaining block studs in swing check valves employed in Emergency Core Cooling System of pressurized water reactors have been the subject of cracking during the past few years. The studs are made from ASTM A-193 Gr. 6 type 410 stainless steel material. USNRC issued an information notice on the issue encouraging utilities to take appropriate actions to monitor/replace the studs so as to prevent a potential dislodging of the valve retaining blocks that can cause flow blockage in the valves. The current paper summarizes the results of a metallurgical investigation aimed at establishing the mechanism and cause(s) of the valve stud cracking. Potential candidate replacement materials to remedy the cracking issue are also considered

  15. Internal flow Patterns of the Horizontal Heat Mode Closed-Loop Oscillating Heat Pipe with Check Valves (HHMCLOHP/CV

    Directory of Open Access Journals (Sweden)

    S. Sangiamsuk

    2013-01-01

    Full Text Available This research was to study the internal flow patterns on heat transfer rates of the Horizontal Heat Mode Closed Loop Oscillating Heat Pipe with Check Valves (HHMCLOHP/CV. The HHMCLOHP/CV was made from a Pyrex glass capillary tube with a 2.4 mm inside diameter. There were 10 meandering turns with 2 check valves. Ethanol and a silver nano-ethanol mixture were used as working fluid. Experimental results found that if working fluid varies from ethanol to a silver nano-ethanol mixture and the evaporator temperature increases the main flow patterns were Slug flow + Annular flow. The main regime of each flow pattern can be determined from the flow pattern map.

  16. Analysis of valve port leakage on direct operated relief valve under foundation vibration%基础振动下直动式溢流阀的阀口泄漏分析

    Institute of Scientific and Technical Information of China (English)

    王蔚坪; 张怀亮; 章国亮

    2015-01-01

    Aiming at the problem that vibration caused by tunnel boring machine (TBM ) during the process of tunneling has effect on leakage in hydraulic components , the relief valve leakage rate caused by foundation vibration and structure parameters was analyzed . Taking the direct operated relief valve installed on TBM as the example , a mathematical model of valve port leakage of relief valve under foundation vibration was established .Critical inlet pressure was determined by calculating the leakage caused by foundation vibrations . Results showed that the amount of valve port leakage increased approximately linearly as the amplitude and frequency of vibration increased . When the spring stiffness was smaller than 1 .3 × 105 N/m ,the valve leakage increased as the spring stiffness increased ;while when the spring stifness equaled to 1 .3 × 105 N/m ,the valve leakage reached the maximum .Reducing spring stiffness and spool mass can decrease the valve port leakage fault caused by foundation vibration significantly ,and improve the working stability of relief valve .%针对硬岩掘进机(TBM )在掘进过程中产生的振动影响液压元件内泄漏的问题,分析基础振动及结构参数对溢流阀阀口泄漏量的影响规律.以安装在TBM基础上的直动式溢流阀为研究对象,建立基础振动下溢流阀的阀口泄漏量数学模型.通过计算基础振动引起的溢流阀阀口泄漏量,确定溢流阀发生阀口泄漏时的临界入口压力.结果表明:阀口泄漏量随着基础振动振幅及频率的增大而近似线性增大;当弹簧刚度小于1.3×105 N/m时,阀口泄漏量随着弹簧刚度的增大而增大;当弹簧刚度为1.3×105 N/m时,阀口泄漏量达到最大值;减小弹簧刚度和阀芯质量可以显著减少因基础振动引起的阀口泄漏故障,从而提高溢流阀的工作稳定性.

  17. Analysis of main steam isolation valve leakage in design basis accidents using MELCOR 1.8.6 and RADTRAD.

    Energy Technology Data Exchange (ETDEWEB)

    Salay, Michael (United States Nuclear Regulatory Commission, Washington, D.C.); Kalinich, Donald A.; Gauntt, Randall O.; Radel, Tracy E.

    2008-10-01

    Analyses were performed using MELCOR and RADTRAD to investigate main steam isolation valve (MSIV) leakage behavior under design basis accident (DBA) loss-of-coolant (LOCA) conditions that are presumed to have led to a significant core melt accident. Dose to the control room, site boundary and LPZ are examined using both approaches described in current regulatory guidelines as well as analyses based on best estimate source term and system response. At issue is the current practice of using containment airborne aerosol concentrations as a surrogate for the in-vessel aerosol concentration that exists in the near vicinity of the MSIVs. This study finds current practice using the AST-based containment aerosol concentrations for assessing MSIV leakage is non-conservative and conceptually in error. A methodology is proposed that scales the containment aerosol concentration to the expected vessel concentration in order to preserve the simplified use of the AST in assessing containment performance under assumed DBA conditions. This correction is required during the first two hours of the accident while the gap and early in-vessel source terms are present. It is general practice to assume that at {approx}2hrs, recovery actions to reflood the core will have been successful and that further core damage can be avoided. The analyses performed in this study determine that, after two hours, assuming vessel reflooding has taken place, the containment aerosol concentration can then conservatively be used as the effective source to the leaking MSIV's. Recommendations are provided concerning typical aerosol removal coefficients that can be used in the RADTRAD code to predict source attenuation in the steam lines, and on robust methods of predicting MSIV leakage flows based on measured MSIV leakage performance.

  18. Effect of Evaporator Lengths and Ratio of Check Valves to Number of Turns on Internal Flow Patterns of a Closed-Loop Oscillating Heat-Pipe With Check Valves

    Directory of Open Access Journals (Sweden)

    S. Rittidech

    2008-01-01

    Full Text Available A visualization study of the internal flow patterns of a closed–loop oscillating heat-pipe with check valves (CLOHP/CV at normal operating condition for several evaporator lengths (Le, and ratio of check valves to number of turns (Rcv has been conducted. This article describes the effects of varying Le, and Rcv on flow patterns. The CLOHP/CV used a Pyrex glass tube with inside diameter of 2.4 mm. The evaporator length of 50 and 150 mm. (the lengths of evaporator, adiabatic and condenser were equal were employed with 10 turns, with Rcv of 0.2 and 1. R123 was used as the working fluid with filling ratio of 50% of internal volume of tube. It was found that the internal flow patterns could be classified according to the Le and Rcv as follows: At the high heat source when the Le decreases the main flow changes from the bubble flow with slug flow to disperse bubble flow. The Rcv decreases the main flow changes from the disperse bubble flow with bubble flow to disperse bubble When the velocity of slug increases, the length of vapor bubbles rapidly decreases and the heat flux rapidly increases.

  19. Waste Heat Recovery by Closed-Loop Oscillating Heat Pipe with Check Valve from Pottery Kilns for Energy Thrift

    Directory of Open Access Journals (Sweden)

    P. Meena

    2008-01-01

    Full Text Available This study aims to design, construct and test the waste heat recovery by closed-loop oscillating heat pipe with check valve from pottery kilns for energy thrift, were used the working fluids with a filling ratio of 50%. The (CLOHO/CV was made of copper capillary tube with inside diameter of 2.03 mm. The lengths of evaporator and condenser section were 20 cm. The lengths of adiabatic section 10 cm. The number of turn was 40 meandering turns. The ratio of number of check valves was 0.04. The evaporator section was heated by hot gas, while the condenser section was cooled by fresh air. From the experiment, it indicated that the working fluid changes form water to R123, the heat transfer rate increased to 4,800 and 7,900 Watts and the effectiveness increased from 0.32 to 0.44. The CLOHP/CV heat exchanger can reduce the quantity of using gas in pottery kilns and achieve energy thrift.

  20. Water hammer analysis. Dynamic simulation model check valve piston; Analisis del golpe de airete. Modelo de simulacion dinamica de valvula de retencion piston

    Energy Technology Data Exchange (ETDEWEB)

    Royo, B.; Valdes, R.

    2012-11-01

    This report contains the description and the results of the dynamic simulation model that has been developed to predict the behaviour of one of our lift check valve design. The aim of the model is not only to simulate the closing process of the valve and to product the magnitude of the water hammer effect that may appear immediately after the valve closing, but also to simulate several design version until obtain the optimum which further minimizes such effect. the input data used for this study ensure reliable results since they represent a real system. (Author)

  1. Selection of Antiagers for Check Valve Rubber%单向阀胶防老剂的选取

    Institute of Scientific and Technical Information of China (English)

    陈丽飞; 金耀程; 韩雪

    2016-01-01

    In order to solve the odor, the antiager in existing check valve rubber formula was replaced, and the tensile strength, elongation at break, hardness(Shaw A), permanent deformation, the hot air aging, flexible crack, ozone aging were measured. Through data analysis, suitable antiager was selected.%通过替换现有成熟单向阀胶料配方中防老剂的品种以解决气味问题,并进行拉伸强度、拉断伸长率、硬度(邵氏 A)、永久变形、热空气老化、屈挠龟裂、臭氧老化测定,通过数据对比分析选取符合潜水帽单向阀性能要求和使用要求的防老剂。

  2. 基于声发射技术的气体阀门内漏诊断%Internal Leakage Diagnosis for Gas Valve Based on AE Technique

    Institute of Scientific and Technical Information of China (English)

    邹兵; 贾招弟; 李伟

    2016-01-01

    Aiming at on-line diagnosis problem about valve leakage in petrochemical enterprises,a simulation test platform of preset defect gates valve leakage is established.By the application of acoustic emission (AE) technology testing means combined with Fluent software simulation of flow field under leakage state, the distribution of AE characteristic parameters are studied in the process of internal leakage.Results show that as the pressure increases,the leakage rate in valve will increase,and the AE signal characteristic parameters (including energy,amplitude,ASL,RMS,etc)will also change regularly.The larger the size of the defect is,the more obvious the change trend shall be.RMS-leakage rate curve is fitting with least squares,and the formula is put forward on quantitative diagnosis for valve leakage.%针对石化企业阀门内漏在线诊断中存在的问题,建立了预置缺陷闸阀内漏模拟试验平台,应用声发射检测技术,结合 Fluent 软件对泄漏状态下流场的模拟,探讨了气体阀门内漏过程中声发射特征参数分布规律。利用小波分析技术,研究了内漏声发射信号频率分布规律。结果表明:随着压差的增大,阀门泄漏率增大,声发射信号特征参数(能量、幅值、平均信号电平等)也随之呈规律性变化,且阀门缺陷尺寸越大,变化趋势越明显。对均方根-泄漏率关系曲线进行最小二乘法拟合,提出阀门内漏定量诊断公式。

  3. 轴流式止回阀动态特性%Dynamic characteristics of axial flow check valve

    Institute of Scientific and Technical Information of China (English)

    杨国来; 伍国果; 刘小雄; 曹文斌; 许敏影

    2013-01-01

    The unsteady fluid flow caused from the moving disc in an axial flow check valve was numerically simulated by means of the computational methods and flow physical models available in CFD code-Fluent.The disc regularly instantaneous movement was realized by the dynamic mesh technique and UDF (user defined function) in Fluent.The transient pressure and velocity were obtained during a period of the disc being closed by means of unstructured mesh,the standard k - e turbulence model.Those transient characteristic curves have been measured experimentally as well,and exhibit good a-greement with the predicted ones,suggesting the numerical simulation method is reliable.Moreover,such dynamic characteristic curves were calculated in the valves in various nominal diameters and external forces and their influences have been identified.Those results will play a critical role in investigation into water hammer effect in the axial flow check valve,and might be useful for check valve design in engineering projects.%基于Fluent软件提供的计算方法和物理模型,利用动网格及用户自定义函数技术对轴流式止回阀的阀瓣运动过程进行动态数值模拟.通过动网格较好地解决了因阀瓣运动而导致的计算区域瞬时变化的问题.利用CFD软件Fluent,采用非结构化网格,标准k-ε湍流模型,模拟了阀瓣关闭的动态过程中,止回阀内压力场和速度场的瞬态变化过程,计算出动态特性曲线,并进行了相应的试验验证.结果表明:运用动网格技术能较好地模拟止回阀内部压力和速度的动态变化,试验结果与数值计算结果趋于一致,验证了数值模拟的可靠性.通过数值模拟不同公称直径和外力下止回阀内的压力场和速度场的瞬态变化,计算出对应的动态特性曲线,并总结了止回阀的公称直径和外力对其动态特性的影响结果,对工程设计与管理具有指导作用.

  4. Comparisons of Heat Transfer Performance of a Closed-looped Oscillating Heat Pipe and Closed-looped Oscillating Heat Pipe with Check Valves Heat Exchangers

    Directory of Open Access Journals (Sweden)

    P. Meena

    2008-01-01

    Full Text Available This research was to study the comparisons of heat transfer performance of closed-looped oscillating heat pipe and closed-looped oscillating heat pipe with check valves heat exchangers with R134a, Ethanol and water were used as the working fluids. A set of heat pipe heat exchanger (CLOHP and CLOHP/CV were made of copper tubes in combination of following dimension: 2.03 mm inside diameter: 40 turns, with 20, 10 and 20 cm for evaporator, adiabatic and condenser sections lengths. The working fluid was filled in the tube at the filling ratio of 50%. The evaporator section was given heat by heater while the condenser section was cooled by air. The adiabatic section was properly insulated. In the test operation, it could be concluded as follows. It indicated that the heat transfer performance of closed-looped oscillating heat pipe with check valves heat exchanger better than closed-looped oscillating heat exchanger.

  5. A piezoelectrically actuated ball valve

    Science.gov (United States)

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

    1972-01-01

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

  6. Micro particle image velocimetry measurements of steady diastolic leakage flow in the hinge of a St. Jude Medical® regent™ mechanical heart valve.

    Science.gov (United States)

    Jun, Brian H; Saikrishnan, Neelakantan; Yoganathan, Ajit P

    2014-03-01

    A number of clinical, in vitro and computational studies have shown the potential for thromboembolic complications in bileaflet mechanical heart valves (BMHV), primarily due to the complex and unsteady flows in the valve hinges. These studies have focused on quantitative and qualitative parameters such as velocity magnitude, turbulent shear stresses, vortex formation, and platelet activation to identify potential for blood damage. However, experimental characterization of the whole flow fields within the valve hinges has not yet been conducted. This information can be utilized to investigate instantaneous damage to blood elements and also to validate numerical studies focusing on the hinge's complex fluid dynamics. The objective of this study was therefore to develop a high-resolution imaging system to characterize the flow fields and global velocity maps in a BMHV hinge. In this study, the steady leakage hinge flow fields representing the diastolic phase during the cardiac cycle in a 23 mm St. Jude Medical regent BMHV in the aortic position were characterized using a two-dimensional micro particle image velocimetry system. Diastolic flow was simulated by imposing a static pressure head on the aortic side. Under these conditions, a reverse flow jet from the aortic to the ventricular side was observed with velocities in the range of 1.47-3.24 m/s, whereas low flow regions were observed on the ventricular side of the hinge with viscous shear stress magnitude up to 60 N/m². High velocities and viscous shearing may be associated with platelet activation and hemolysis, while low flow zones can cause thrombosis due to increased residence time in the hinge. Overall, this study provides a high spatial resolution experimental technique to map the fluid velocity in the BMHV hinge, which can be extended to investigate micron-scale flow domains in various prosthetic devices under different hemodynamic conditions.

  7. New Onset Significant Paravalvular Leakage in a Patient with Mechanical Prosthetic Aortic Valve after Exposure to Magnetic Resonance Imaging. Is There Any Relevance?

    Directory of Open Access Journals (Sweden)

    Arash Hashemi

    2013-05-01

    effects on mechanical prosthetic valves in mitral position even with low-strength field equal to 1.5 Tesla. The aforementioned effect is related to the field strength linearly. This issue points that we should be alarmed to study these patients before including them in MRI study and perhaps excluding them from this experience. (1, 2, 5. We reported a 75 year old gentlemen with history of severe aortic stenosis and aortic valve replacement by ST Jude Medical prosthesis three years ago. He referred to our clinic due to the new onset dyspnea on exertion with New York Heart Association (NYHA function class III after a thoracic MRI study for the evaluation of thoraco-lumbar discopathy that had been done by Siemens machine with the main static magnetic field strength (B0 of 1.58 Tesla and maximum average body weight of specific absorption rate (SAR equal to 800 J/kg. The MRI scanning had been taken for 13 minutes and the patient location was feet first in the MR system bore entrance. This patient was well and had no cardiac complaints during three years passing his surgery until his MRI study. His functional capacity was acceptable prior to this visit. He had undergone two transthoracic (TTE evaluations after his surgery as a part of routine protocol in our center just after his surgery and again four weeks later showed no complications. Also he even had undergone TTE with transesophageal echocardiographic (TEE study, three months earlier for more evaluation of his sudden, short-term and anxious dyspnea, and no abnormalities were reported. In the evaluation of his new onset and progressive dyspnea which occurred after his recent MRI study and was not associated with any other condition, we found a 2/6 diastolic murmur at right para-sternal border and our evaluation by echocardiography (both TTE and TEE studies showed Bilateral moderate paravalvular leakage. We haven’t found any other logical explanation for this new onset and sudden bilateral paravalvular leakage except for

  8. Checking the Safety Valve with a Pressure Gauge Error Analysis and Reasonable Selection%安全阀校验用压力表误差分析与合理选用

    Institute of Scientific and Technical Information of China (English)

    常卫东

    2015-01-01

    Safety valve is a pressure relief device, plays an important role in security of pressure equipment, check after passing to the installation and use, the safety valve in the cold off-line checking with pressure gauge, precision, error range and the influence factors are deep discussed, grasp the technical aspects, has important significance on accuracy of safety valve calibration data.%安全阀是一种超压泄放装置,对承压设备起着重要的安全保障作用,校验合格后才能安装使用,对安全阀冷态离线校验用压力表精度、误差、量程及影响因素等方面进行深层次论述,抓好技术环节,对安全阀校验数据的准确性具有重要意义.

  9. Numerical Simulation and Experimental Study on the Tilt Double Disc Check Valve%斜置双瓣止回阀内部流态的模拟与试验研究

    Institute of Scientific and Technical Information of China (English)

    杜卫; 洪顺军; 吴义勇; 李志鹏; 何敬行; 周永芳

    2016-01-01

    With improving the existing problems of small opening angle and small flow resistance coefficient of common check valves,a new type of tilt double disc check valve was designed.analyses of the internal flow characteristics of the check valve were conducted when the check valve was operating at the angel of 30°,50°,70°,80°or entirely opened.Calculating the flow resistance coefficient and flow coefficient.It was tested pressure loss characteristics and flow characteristics test,in addition,the flow resistance coefficients and discharge coefficient were compared between simulation results.The results was that the simula-tion results and experimental results are consistent,and when the opening angle of the check valve was larger,the pressure loss would be less,the flow resistance coefficient would be smaller and the discharge coefficient would be larger,the flow capacity would be better.Through the numerical simulation and experimental study on the tilt double disc check valve,the design of the new tilt double disc check valve has guidance to the energy conservation of the fluid system.%为了改进普通止回阀存在的开启角度小、流阻系数大等不足,设计一种新型斜置双瓣止回阀,对其在30°、50°、70°、80°及全开工况下的内部流动特性进行分析,计算出流阻系数及流量系数.对其进行压力损失特性试验及流量特性试验,计算出每个工况下的流阻系数及流量系数,将其与模拟数据进行对比分析.研究结果表明,斜置双瓣止回阀的模拟结果与试验结果比较接近,开启角度大,压力损失小,流阻系数小,流量系数大,通流能力好.通过对斜置双瓣止回阀进行数值模拟及试验研究,斜置双瓣止回阀的设计对流体系统节能具有指导意义.

  10. Research on the Acoustic Emission Signal Feature for the Inner Leakage of Valves%阀门内漏声发射检测信号特征研究

    Institute of Scientific and Technical Information of China (English)

    刘治超; 张悠江

    2015-01-01

    阀门在天然气管道运输中具有重要的作用,阀门内漏会给天然气管道运输造成安全隐患。采集阀门内漏的声发射信号,采用改进的小波阈值去噪方法对采集的信号进行降噪处理,提高信号的信噪比,进而提取降噪后信号的频域峰值和峰值频率,探究阀门内漏的信号特征,为阀门内漏检测提供参考。%Valves have an important role in the transport of natural gas,and the safety operation of gas pipelines is threatened by valve inner leakage.The acoustic emission signals are collected,and the improved threshold de-noising algorithm is applied to signal analysis,in order to improve the signal-to-noise-ratio,and decrease the root-mean-square-error (RMSE)value.Then,the frequency domain peak and peak frequency of the de-noising signal are extracted to research the acoustic e-mission signal feature for the inner leakage of valve and lay the foundation for the valve leak de-tection.

  11. 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.

  12. Effect of Check Valve on Consequences of Coolant Pump Rotor Seizure Accident for EPR Reactor%止回阀对EPR反应堆主泵卡轴事故后果的影响

    Institute of Scientific and Technical Information of China (English)

    陈秋炀; 周拥辉

    2012-01-01

    分析计算欧洲先进压水堆(EPR)反应堆主泵卡轴事故,并对比在主泵出口安装止回阀和没有安装止回阀模型的卡轴事故安全分析.结果表明,在EPR主泵卡轴事故中,止回阀可增加模型堆芯进口流量约4%,有利于堆芯的冷却.止回阀可显著地提高堆芯最小偏离泡核沸腾比(DNBR),降低堆芯偏离泡核沸腾(DNB)份额,降低包壳温度约14℃.模型分析结果表明,在主泵卡轴事故工况下,主泵出口安装止回阀可更好地维持堆芯的完整性.%Counter current flow phenomenon would appear during reactor coolant pump rotor seizure accident. Present work analyzes the coolant pump rotor seizure accident for European Pressurized Reactor (EPR). The accident safety analysis results of model with check valve and without check valve are compared. It can be found that the check valve can increase the core inlet flow rate of model about 4%. The increasing of coolant flow rate is beneficial to the reactor core cooling. Check valve can increase the minimum departure from nucleate boiling ratio (DNBR), reduce the departure from nucleate boiling (DNB) fraction and the fuel rod cladding temperature about 14℃ during coolant pump rotor seizure accident. The analyses results show that the model with check valve can maintain the integrity of nuclear fuel rod effectively during reactor coolant pump rotor seizure accident.

  13. Light water reactor pressure isolation valve performance testing

    International Nuclear Information System (INIS)

    The Light Water Reactor Valve Performance Testing Program was initiated by the NRC to evaluate leakage as an indication of valve condition, provide input to Section XI of the ASME Code, evaluate emission monitoring for condition and degradation and in-service inspection techniques. Six typical check and gate valves were purchased for testing at typical plant conditions (550F at 2250 psig) for an assumed number of cycles for a 40-year plant lifetime. Tests revealed that there were variances between the test results and the present statement of the Code; however, the testing was not conclusive. The life cycle tests showed that high tech acoustic emission can be utilized to trend small leaks, that specific motor signature measurement on gate valves can trend and indicate potential failure, and that in-service inspection techniques for check valves was shown to be both feasible and an excellent preventive maintenance indicator. Life cycle testing performed here did not cause large valve leakage typical of some plant operation. Other testing is required to fully understand the implication of these results and the required program to fully implement them. (author)

  14. Effect of Inner Diameter and Inclination Angles on Operation Limit of Closed-Loop Oscillating Heat-Pipes with Check Valves

    Directory of Open Access Journals (Sweden)

    P. Meena

    2008-01-01

    Full Text Available This research was to study the effect of inner diameter and inclination angles on operation limit of a closed loop oscillating heat pipes with check valves (CLOHP/CV. A set of CLOHP/CV was made of copper tubes in combination of following dimension: 1.77 and 2.03 mm inside diameter: 10 turn, with R123 was used as the working fluid. The working fluid was filled in the tube at the filling ratio of 50%. The inclination angles were 0, 20, 40, 60, 80 and 90° with 5 equal lengths for evaporator, adiabatic and condenser sections. The evaporator section was given heat by heater while the condenser section was cooled by volume water in a cold bath. The adiabatic section was properly insulated. In the test operation, it could be concluded as follows. It indicated that when the inner diameter changed from 1.77-2.03 mm the critical temperature increased. And when increase the inclination angles from 0 until to 90° the critical temperature increased.

  15. Effect of Evaporator Section Lengths and Working Fluids on Operational Limit of Closed Loop Oscillating Heat Pipes with Check Valves (CLOHP/CV

    Directory of Open Access Journals (Sweden)

    P. Meena

    2009-01-01

    Full Text Available This research aims to the effect of evaporator section lengths and working fluids on operational limit of closed loop oscillating heat pipes with check valves (CLOHP/CV with R123 Ethanol and Water were used as the working fluids. A set of CLOHP/CV was made of copper tubes in combination of following dimension: 1.77 mm inside diameter: 10 turns: 5, 10 and 15 cm equal lengths for evaporator, adiabatic and condenser sections. The working fluid was filled in the tube at the filling ratio of 50%. The evaporator section was given heat by heater while the condenser section was cooled by volume water in a cold bath. The adiabatic section was properly insulated. In the test operation. Which the temperature at the adiabatic section was controlled at 60°C in steady-state condition. From The obtained results obtained, it could be concluded as follows. When the evaporator lengths increased from 5 cm to 10 and 15 cm the critical heat transfer flux decreased. There was working fluids change from R123 to Ethanol and water the critical heat flux decreased.

  16. 仿生创新方法及其在止回阀设计中的应用%A bionic innovation method and its application in check valve design

    Institute of Scientific and Technical Information of China (English)

    赖朝安

    2013-01-01

    Analyses the advantages and disadvantages of TRIZ methods and bionics, the innovative design approach based on a combination of TRIZ and bionics was put forward. The traditional check valves such as ball valve and wafer check valves have some shortcomings, such as the high resistance coefficient. Basing on this method, a new type of pyramid orange-peel check valve was design. When the disc is open,the peels are beside the channel;when the disc is close,the peels are in the form of pyramid, thus,it can effectively reduce the area of obstructing water. Experimental analysis was done for the flow field of the check valve. The results show that the flow resistance coefficient is much less than that of conventional check valve. It also shows that it has better capacity for water flowing and energy conservation.%针对发明问题解决理论(TRIZ)方法与仿生学的优缺点,提出基于TRIZ与仿生学相结合的仿生创新设计方法.采用该方法,针对传统止回阀如球形止回阀、对夹式止回阀等流阻系数大的缺点,设计出一种新型的金字塔型多瓣止回阀,当流体正向流动时,阀瓣打开并位于流道侧面;当流体回流时,阀瓣关闭处于斜立状态,因此可以有效地减少阀瓣开关行程,并减小对流体的阻力与作用时间,降低了流阻系数.实验证明:该止回阀阀门的流通能力很强,能起到一定的节能作用.

  17. Proportional directional valve based automatic steering system for tractors

    Institute of Scientific and Technical Information of China (English)

    Jin-yi LIU; Jing-quan TAN; En-rong MAO; Zheng-he SONG; Zhong-xiang ZHU‡

    2016-01-01

    Most automatic steering systems for large tractors are designed with hydraulic systems that run on either constant flow or constant pressure. Such designs are limited in adaptability and applicability. Moreover, their control valves can unload in the neutral position and eventually lead to serious hydraulic leakage over long operation periods. In response to the problems noted above, a multifunctional automatic hydraulic steering circuit is presented. The system design is composed of a 5-way-3-position proportional directional valve, two pilot-controlled check valves, a pressure-compensated directional valve, a pressure-compensated flow regulator valve, a load shuttle valve, and a check valve, among other components. It is adaptable to most open-center systems with constant flow supply and closed-center systems with load feedback. The design maintains the lowest pressure under load feedback and stays at the neutral position during unloading, thus meeting the requirements for steering. The steering controller is based on proportional-integral-derivative (PID) running on a 51-microcontroller-unit master control chip. An experimental platform is developed to establish the basic characteristics of the system subject to stepwise inputs and sinusoi-dal tracking. Test results show that the system design demonstrates excellent control accuracy, fast response, and negligible leak during long operation periods.

  18. New Onset Significant Paravalvular Leakage in a Patient with Mechanical Prosthetic Aortic Valve after Exposure to Magnetic Resonance Imaging. Is There Any Relevance?

    OpenAIRE

    Arash Hashemi; Azin Alizadehasl

    2013-01-01

    Many studies have evaluated heart valve prostheses and annuloplasty rings for Magnetic Resonance (MR) issues, particularly with regard to the magnetic field interactions associated with MR systems operating at field strength more than 4-Tesla. Many of these studies showed relatively minor magnetic field interactions, and according to their conclusion, MR procedure is not considered to be so hazardous for a patient with any prosthetic valve or annuloplasty ring. However, there has been everlas...

  19. Micro Particle Image Velocimetry Measurements of Steady Diastolic Leakage Flow in the Hinge of a St. Jude Medical® Regent™ Mechanical Heart Valve

    OpenAIRE

    Jun, Brian H.; Saikrishnan, Neelakantan; Yoganathan, Ajit P.

    2013-01-01

    A number of clinical, in vitro and computational studies have shown the potential for thromboembolic complications in bileaflet mechanical heart valves (BMHV), primarily due to the complex and unsteady flows in the valve hinges. These studies have focused on quantitative and qualitative parameters such as velocity magnitude, turbulent shear stresses, vortex formation and platelet activation to identify potential for blood damage. However, experimental characterization of the whole flow fields...

  20. Respiratory exposure control valve

    International Nuclear Information System (INIS)

    We have designed a new, three-way valve that separates inhaled and exhaled air in systems for inhalation exposure. A single-channel model of the valve was constructed and tested: with a control fluid pressure of 10 psi, the valve was cycled 36,000 times without diaphragm failure. No valve leakage was detected before or after the completion of the test. A 3-channel valve model was constructed this year and will undergo testing in FY 1979, followed by development and testing of the control system

  1. Development of Injection System with Inner-Set Check Valve for Die Casting Machine%压铸机内置单向阀压射系统的研制

    Institute of Scientific and Technical Information of China (English)

    孟凡义; 徐越; 崔嘉琪

    2012-01-01

    压铸机内置单向阀压射系统,主要解决传统压铸机利用浮动活塞增压的三级压射系统建压时间相对较长引起的缺陷问题.安装在增压活塞杆内的带弹簧复位的内置单向阀,可以借助弹簧的力量快速关闭锥面开始增压,缩短了建压时间.在压射活塞右端与内置单向阀之间增加压射活塞缓冲结构,慢压射时进油口的大小随着压射活塞移动而逐渐增加,实现了慢压射速度匀加速的目的.%Injection system with inner-set check valve for die casting machine was development to solve the problems of the long establishment-time in three-stage injection system in traditional die casting machine due to use floating piston to pressurization. Inner-set check valve with spring reset which was installed in pressurization piston rod could rapidly switch off cone face with the help of spring to shorten established-pressure time by pressurization. Injected piston buffer mechanism was designed between the right end of injected piston and inner-set check valve, so the size of oil entrance during slow injection process is increased gradually with the move of injected piston, realizing the proportional acceleration of slow injection velocity.

  2. When a Mechanical Valve Goes Freestyle: A Patient Tailored Valve-In-Valve Implantation.

    Science.gov (United States)

    François, J; Cathenis, K; Hamerlijnck, R

    2015-01-01

    In case of a redo operation after a full root replacement there are two possible options: replacing the entire root or performing a more conservative valve-in-valve implantation. Regarding the relatively high morbidity and mortality of a redo root replacement, the valve-in-valve implantation is the preferred choice if technically feasible. We present the case of a valve-in-valve implantation with a St. Jude mechanical valve in a Medtronic bioprosthesis in a 57-year old man. Follow-up echocardiography after 1 month showed a mean gradient of 17 mmHg and no paravalvular leakage. The combination of a St. Jude bileaflet mechanical valve implanted in a Freestyle root prosthesis has not been described. This case shows that patient tailored treatment with a St. Jude bileaflet mechanical valve in a Freestyle aortic root valve can be safely performed and might be the preferred choice for younger patients, if technically feasible. PMID:26560005

  3. 控制管路系统中止回阀故障分析%Check valve failure analysis in the control piping system

    Institute of Scientific and Technical Information of China (English)

    刘爱明; 蒋廉华; 刘宇; 李开烨

    2013-01-01

    According to the important role of check value which used in the control piping system of electric locomotive .Through analyz-ing the phenomenon of check value failure and the cause of its ,the author gives out some methods .%  针对止回阀在电力机车控制管路系统中所起的重要作用,分析了止回阀的故障现象,对其原因进行探讨,并提出改进方法。

  4. Lockup Analysis and Study on Pilot Controlled Check Valve%液控单向阀锁死的原因分析与研究

    Institute of Scientific and Technical Information of China (English)

    李云; 李荣; 高兴利

    2009-01-01

    本文分析了打包机的锁门机构回路中,双向液控单向阀被锁死的原因.当液控单向阀的开启比大于液压缸的速比时,才有可能打开液控单向阀.所以选用液控单向阀应考虑与系统的压力及被锁紧的最大负载之间是否匹配,以避免液控单向阀被锁死.%The paper introduces the reason that the pilot controlled check value is locked in locking mechanism loop of baler. Only just the unlock ratio of pilot controlled check value is greater than the velocity ratio of oil cylinder, it may open up pilot controlled check value. To avoid pilot controlled check value of being locked, you should think that if it matches systemic pressure and maximum load of being locked.

  5. Study on Capacity Check Method of Feed Water Heater Safety Valves in Nuclear Power Plants%核电厂高加安全阀的排放容量校核方法研究

    Institute of Scientific and Technical Information of China (English)

    石建中; 黄超; 王志明; 胡友情

    2013-01-01

    火电厂的高加安全阀通常按照HEI标准推荐的原则进行选型计算,但因核电厂的高加一般要接受来自汽水分离再热器( MSR)的大量高温疏水,而当其疏水调节阀在全开位置失效时将有大量高压蒸汽直接进入高加,使其有发生超压的风险。因此,核电机组的高加安全阀选型除了要遵循HEI标准外,还需针对某些特殊工况进行校核。在分析了给水加热器、疏水调节阀以及抽汽管道的特性方程的基础上,从能量平衡的观点建立了确定系统平衡工作点的计算方法,利用该方法可简易计算出各种特殊工况的平衡工作压力,从而进一步判断安全阀的容量是否满足安全排放要求。%The selection of the high pressure feed water heater′s safety valve usually follows the principle recommended by HEI standards in thermal power plant .However ,the nuclear power plant′s heaters gener-ally need to accept a lots of drain from a moisture separator reheater ( MSR).When the drain regulating valve was failure in fully open position ,a large number of high pressure steam will directly goes into the heater.It make high-pressure heater have a risk of overpressure .Therefore,the safety valve selection of the heaters for nuclear power plants not only need to follow the HEI standards ,but also need to check his capacity in certain special conditions .The paper established a calculation method to determine the static running point of the heaters based on characteristic equations of the feed water heater , drain regulating valve and steam extraction pipings ,and energy balance principle .The method can be used to calculate the equilibrium pressure of various special running conditions ,so further determine whether the capacity of the safety valve meets the requirements of safety and emissions .

  6. 轴流式止回阀流阻特性检测方法的探讨%Research on testing method of flow resistance characteristics of axial flow check valve

    Institute of Scientific and Technical Information of China (English)

    缪克在; 林美

    2012-01-01

    Testing principle of flow resistance performances, design of testing equipment, inspection and analysis of axial check valve are introduced, and testing points selection method based on flow rate for using the function of pressure drop and flow rate is discussed, while recommended flow rate ranges for the testing of those samples with different nominal size are put forward.%阐述了轴流式止回阀的流阻性能测试原理、检测装置设计及检验与分析,探讨了利用压差一流速函数关系,以流速为依据选取测试点,并提出了不同公称尺寸轴流式止回阀的推荐测试点选取方法。

  7. Valve Disease

    Science.gov (United States)

    ... Myocarditis Obstructive Sleep Apnea Pericarditis Peripheral Vascular Disease Rheumatic Fever Sick Sinus Syndrome Silent Ischemia Stroke Sudden Cardiac Arrest Vulnerable Plaque Valve Disease | Share Related terms: heart valves, valve insufficiency, valve regurgitation, valve stenosis, valvular ...

  8. 南水北调中线干线工程渠道逆止阀的施工工艺和质量控制%Construction Technique and Quality Control of Channel Check Valve in the Middle Route of South-to-North Water Diversion Project

    Institute of Scientific and Technical Information of China (English)

    高大勇; 朱云飞

    2013-01-01

    以南水北调鹤壁段第二施工标段为例,介绍了渠道逆止阀的安装工艺,如遵循“基础开挖→回填第一层粗砂→埋置集水暗管→回填暗管周边粗砂→铺设保温板→铺设复合土工膜→安装逆止阀”的施工流程;质量控制方法,如控制逆止阀安装位置、高程、数量等。%The installation technique of channel check valve is introduced by taking the example of Hebi section , the second construction section of South-to-North Water Diversion Project .The technique are in accordance with following orders:foundation excavation , backfilling the first layer of coarse sand , burying water collecting pipe , backfilling coarse sand surrounding pipes , laying warm keeping board , laying composite geomembrane and installing check valve .Mean-while , the quality control methods , such as control check valve installation position , elevation and quantity are also covered .

  9. 2D SIMPLIFIED SERVO VALVE

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel pilot stage valve called simplified 2D valve, which utilizes both rotary and linear motions of a single spool, is presented.The rotary motion of the spool incorporating hydraulic resistance bridge, formed by a damper groove and a crescent overlap opening, is utilized as pilot to actuate linear motion of the spool.A criterion for stability is derived from the linear analysis of the valve.Special experiments are designed to acquire the mechanical stiffness, the pilot leakage and the step response.It is shown that the sectional size of the spiral groove affects the dynamic response and the stiffness contradictorily and is also very sensitive to the pilot leakage.Therefore, it is necessary to establish a balance between the static and dynamic characteristics in deciding the structural parameters.Nevertheless, it is possible to sustain the dynamic response at a fairly high level, while keeping the leakage of the pilot stage at an acceptable level.

  10. Heart valve surgery

    Science.gov (United States)

    Valve replacement; Valve repair; Heart valve prosthesis; Mechanical valves, Prosthetic valves ... made materials, such as metal (stainless steel or titanium) or ceramic. These valves last the longest, but ...

  11. Globe stability during simulated vitrectomy with valved and non-valved trocar cannulas

    Directory of Open Access Journals (Sweden)

    Abulon DJ

    2015-09-01

    Full Text Available Dina Joy Abulon,1 Martin Charles,2 Daniel E Charles21Global Medical Affairs, Alcon Laboratories, Inc., Lake Forest, CA, USA; 2Centro Oftalmológico Dr Charles, Buenos Aires, ArgentinaPurpose: To compare the effects of valved and non-valved cannulas on intraocular pressure (IOP, fluid leakage, and vitreous incarceration during simulated vitrectomy.Methods: Three-port pars plana incisions were generated in six rubber eyes using 23-, 25-, and 27-gauge valved and non-valved trocar cannulas. The models were filled with air and IOP was measured. Similar procedures were followed for 36 acrylic eyes filled with saline solution. Vitreous incarceration was analyzed in eleven rabbit and twelve porcine cadaver eyes.Results: In the air-filled model, IOP loss was 89%–94% when two non-valved cannulas were unoccupied versus 1%–5% when two valved cannulas were unoccupied. In the fluid-filled model, with non-valved cannulas, IOP dropped while fluid leaked from the open ports. With two open ports, the IOP dropped to 20%–30% of set infusion pressure, regardless of infusion pressure and IOP compensation. The IOP was maintained in valved cannulas when one or two ports were left open, regardless of IOP compensation settings. There was no or minimal fluid leakage through open ports at any infusion pressure. Direct microscopic analysis of rabbit eyes showed that vitreous incarceration was significantly greater with 23-gauge non-valved than valved cannulas (P<0.005, and endoscopy of porcine eyes showed that vitreous incarceration was significantly greater with 23-gauge (P<0.05 and 27-gauge (P<0.05 non-valved cannulas. External observation of rabbit eyes showed vitreous prolapse through non-valved, but not valved, cannulas.Conclusion: Valved cannulas surpassed non-valved cannulas in maintaining IOP, preventing fluid leakage, and reducing vitreous incarceration during simulated vitrectomy.Keywords: IOP, fluid leakage, vitreous incarceration

  12. A jazz-based approach for optimal setting of pressure reducing valves in water distribution networks

    Science.gov (United States)

    De Paola, Francesco; Galdiero, Enzo; Giugni, Maurizio

    2016-05-01

    This study presents a model for valve setting in water distribution networks (WDNs), with the aim of reducing the level of leakage. The approach is based on the harmony search (HS) optimization algorithm. The HS mimics a jazz improvisation process able to find the best solutions, in this case corresponding to valve settings in a WDN. The model also interfaces with the improved version of a popular hydraulic simulator, EPANET 2.0, to check the hydraulic constraints and to evaluate the performances of the solutions. Penalties are introduced in the objective function in case of violation of the hydraulic constraints. The model is applied to two case studies, and the obtained results in terms of pressure reductions are comparable with those of competitive metaheuristic algorithms (e.g. genetic algorithms). The results demonstrate the suitability of the HS algorithm for water network management and optimization.

  13. 49 CFR 179.300-13 - Venting, loading and unloading valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Venting, loading and unloading valves. 179.300-13... Venting, loading and unloading valves. (a) Valves shall be of approved type, made of metal not subject to rapid deterioration by lading, and shall withstand tank test pressure without leakage. The valves...

  14. Propellant isolation shutoff valve program

    Science.gov (United States)

    Merritt, F. L.

    1973-01-01

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

  15. Inward Leakage in Tight-Fitting PAPRs

    OpenAIRE

    Frank C. Koh; Johnson, Arthur T.; Rehak, Timothy E.

    2011-01-01

    A combination of local flow measurement techniques and fog flow visualization was used to determine the inward leakage for two tight-fitting powered air-purifying respirators (PAPRs), the 3M Breathe-Easy PAPR and the SE 400 breathing demand PAPR. The PAPRs were mounted on a breathing machine head form, and flows were measured from the blower and into the breathing machine. Both respirators leaked a little at the beginning of inhalation, probably through their exhalation valves. In both cases,...

  16. Axioms for Information Leakage

    OpenAIRE

    Alvim, Mário S.; Chatzikokolakis, Konstantinos; McIver, Annabelle; Morgan, Carroll; Palamidessi, Catuscia; Smith, Geoffrey

    2016-01-01

    Quantitative information flow aims to assess and control the leakage of sensitive information by computer systems. A key insight in this area is that no single leakage measure is appropriate in all operational scenarios; as a result, many leakage measures have been proposed, with many different properties. To clarify this complex situation, this paper studies information leakage axiomatically, showing important dependencies among different axioms. It also establishes a completeness result abo...

  17. Component external leakage and rupture frequency estimates

    International Nuclear Information System (INIS)

    In order to perform detailed internal flooding risk analyses of nuclear power plants, external leakage and rupture frequencies are needed for various types of components - piping, valves, pumps, flanges, and others. However, there appears to be no up-to-date, comprehensive source for such frequency estimates. This report attempts to fill that void. Based on a comprehensive search of Licensee Event Reports (LERs) contained in Nuclear Power Experience (NPE), and estimates of component populations and exposure times, component external leakage and rupture frequencies were generated. The remainder of this report covers the specifies of the NPE search for external leakage and rupture events, analysis of the data, a comparison with frequency estimates from other sources, and a discussion of the results

  18. Investigation of valve failure problems in LWR power plants

    International Nuclear Information System (INIS)

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

  19. Globe stability during simulated vitrectomy with valved and non-valved trocar cannulas

    OpenAIRE

    Abulon DJ; Charles M; Charles

    2015-01-01

    Dina Joy Abulon,1 Martin Charles,2 Daniel E Charles21Global Medical Affairs, Alcon Laboratories, Inc., Lake Forest, CA, USA; 2Centro Oftalmológico Dr Charles, Buenos Aires, ArgentinaPurpose: To compare the effects of valved and non-valved cannulas on intraocular pressure (IOP), fluid leakage, and vitreous incarceration during simulated vitrectomy.Methods: Three-port pars plana incisions were generated in six rubber eyes using 23-, 25-, and 27-gauge valved and non-valved trocar can...

  20. Globe stability during simulated vitrectomy with valved and non-valved trocar cannulas

    OpenAIRE

    Charles, Martin

    2015-01-01

    Dina Joy Abulon,1 Martin Charles,2 Daniel E Charles21Global Medical Affairs, Alcon Laboratories, Inc., Lake Forest, CA, USA; 2Centro Oftalmológico Dr Charles, Buenos Aires, ArgentinaPurpose: To compare the effects of valved and non-valved cannulas on intraocular pressure (IOP), fluid leakage, and vitreous incarceration during simulated vitrectomy.Methods: Three-port pars plana incisions were generated in six rubber eyes using 23-, 25-, and 27-gauge valved and non-valved tr...

  1. Land-use Leakage

    Energy Technology Data Exchange (ETDEWEB)

    Calvin, Katherine V.; Edmonds, James A.; Clarke, Leon E.; Bond-Lamberty, Benjamin; Kim, Son H.; Wise, Marshall A.; Thomson, Allison M.; Kyle, G. Page

    2009-12-01

    Leakage occurs whenever actions to mitigate greenhouse gas emissions in one part of the world unleash countervailing forces elsewhere in the world so that reductions in global emissions are less than emissions mitigation in the mitigating region. While many researchers have examined the concept of industrial leakage, land-use policies can also result in leakage. We show that land-use leakage is potentially as large as or larger than industrial leakage. We identify two potential land-use leakage drivers, land-use policies and bioenergy. We distinguish between these two pathways and run numerical experiments for each. We also show that the land-use policy environment exerts a powerful influence on leakage and that under some policy designs leakage can be negative. International “offsets” are a potential mechanism to communicate emissions mitigation beyond the borders of emissions mitigating regions, but in a stabilization regime designed to limit radiative forcing to 3.7 2/m2, this also implies greater emissions mitigation commitments on the part of mitigating regions.

  2. 单向阀对双增压气路中气体流向影响的分析与研究%Research and Analysis on the Air Flow Direction Affected by Check Valve in Pressurization Gas Path of Two Electric Superchargers

    Institute of Scientific and Technical Information of China (English)

    姚春德; 韩伟强; 武炎; 侯亚帮; 徐成耀; 路平

    2012-01-01

    搭建由双电动增压器与单向阀组成的试验台架并模拟研究单向阀对双增压气路中气体流向的影响规律,以提高电动增压器的补气效率,从而增大公交车柴油机工况突变时的进气量,改善瞬态烟度.通过向两个电动增压器设定不同的转速,分别模拟公交车柴油机的废气涡轮增压器和附加用于急加速补气的电动增压器,研究并分析在气路上设置单向阀前后对双增压气路中气体流向的影响.试验结果表明,电动增压器的流量大于废气涡轮增压器的流量时,出口总流量在无单向阀时大致等于废气涡轮增压器提供的流量,增加电动增压器的流量不会改变出口总流量,电动增压器补气效率低,柴油机的进气量未得到改善.有单向阀时,出口总流量随电动增压器流量增加而增大,电动增压器补气效率高,柴油机的进气量增大;电动增压器的流量小于废气涡轮增压器的流量时,电动增压器与单向阀不影响出口总流量,出口总流量与有旁通气路无单向阀时相同,即电动增压器不工作时不影响原机的进气量.%A testing rig, consisting of two electric superchargers and a check valve, used to simulate and investigate the air flow direction affected by check valve in pressurization gas path is built. Through this way higher fill gas efficiency of electric supercharger can be achieved, which will give rise to more air inflow of diesel engine at its working condition mutation, improving transient FSN. By setting the speed of the two electric Superchargers respectively, one is used to simulate the turbocharger of the diesel engine of a bus and the other is used to simulate electric supercharger which supplys additional air for a sharp acceleration, to study the air flow direction affected by check valve in pressurization gas path. Testing results indicate that without the check valve, when the flow rate of the electric supercharger is larger than

  3. Thrombogenicity and Reoperation of the St. Jude Medical Silzone (R) valve : A comparison with the conventional St. Jude medical valve

    NARCIS (Netherlands)

    Stalenhoef, JE; Mellema, EC; Veeger, NJGM; Ebels, T

    2003-01-01

    Background and aim of the study: The St. Jude Medical Silzone(R) valve was withdrawn from the market after an interim analysis of the AVERT study revealed a 2.76% incidence of paravalvar leakage leading to valve re-replacement, compared with only 1.02% in the control group. Additionally, an increase

  4. 贵—广Ⅱ宝安站极2Y3阀因无回报信号导致极2跳闸的故障分析及相关反措的建议%Analysis and Suggestions on Pole 2 Strip Caused by No Check Back Signal from Y3 Valve of GGH Baoan Station

    Institute of Scientific and Technical Information of China (English)

    李侠; 马振军

    2012-01-01

    The light triggered thyristor valves, which are directly triggered by laser, are used in Guizhou-Guangdong ±500 kV HVDC II power transmission lines. To ensure safe and reliable operation, thyristor voltage mornitors(TVM) are used to have on-line momitoring on each thyristor. By light cables, TVM sends real-time feedback signal to VBE, whose single-chip can judge the default of thyristor valves by reading such check back signals. When the number of default thyristors exceeds the number of thyristor redundancy, trip signal is sent. The author analyzes the default and provides the related suggestions on Pole 2 trip caused by no check back signal from Y3 valve of CCII Baoan station, 12th March, 2009 and 29 th May 2010.%中国贵—广Ⅱ±500 kV高压直流输电工程中均采用激光脉冲直接触发晶闸管的直接光控晶闸管换流阀(以下简称LTT阀).为了确保换流阀的安全可靠运行,对换流阀中的每个晶闸管用晶闸管电压监测电子线路(thyristor voltage momitoring,TVM)进行在线监测.TVM实时用回报信号将监测的结果通过光缆送往阀底部电子设备柜(VBE)中.VBE中的单片机监测系统根据回报信号分析判定晶闸管的故障,当阀内故障晶闸管教超过设计允许的冗余数,产生相应的跳闸信号.笔者就2009年3月12日和2010年5月29日贵—广Ⅱ宝安站极2 Y3阀因无回报信号导致极2跳闸的故障进行了分析,得出:跳闸故障并非由阀或VBE故障引起,而是由阀侧电压不稳定或扰动引起的结论,并提出相关反措的建议.

  5. Model for Electromagnetic Information Leakage

    Directory of Open Access Journals (Sweden)

    Mao Jian

    2013-09-01

    Full Text Available Electromagnetic leakage will happen in working information equipments; it could lead to information leakage. In order to discover the nature of information in electromagnetic leakage, this paper combined electromagnetic theory with information theory as an innovative research method. It outlines a systematic model of electromagnetic information leakage, which theoretically describes the process of information leakage, intercept and reproduction based on electromagnetic radiation, and analyzes amount of leakage information with formulas.  

  6. Colon anastomotic leakage

    DEFF Research Database (Denmark)

    Pommergaard, Hans-Christian; Achiam, Michael Patrick; Rosenberg, Jacob

    2014-01-01

    PURPOSE: Colon anastomotic leakage remains a serious and common surgical complication. Animal models are valuable to determine the pathophysiological mechanisms and to evaluate possible methods of prevention. The aim of this study was to develop an optimal model of clinical colon anastomotic...... group [0.49 N ± 0.15] (p = 0.091). CONCLUSIONS: This mouse model closely mimics clinical colon anastomotic leakage in humans. The model is of high clinical relevance, since anastomotic leakage has a similar cause, incidence and manifestations in humans....

  7. Valve's Way

    Directory of Open Access Journals (Sweden)

    Phanish Puranam

    2015-06-01

    Full Text Available What can we learn from outliers? While statisticians rightly warn us against their non-representativeness, we believe it is also true that thinking carefully about what makes them atypical may improve our understanding of the typical case. This is the premise behind the Organization Zoo series. Valve Corporation (Valve is an unusual firm. It is a rare example of a firm that appears to operate without any formal hierarchy in its organization. What can we learn about the viability of authority hierarchies from Valve’s way of organizing? We wrote a brief account of Valve based on public information sources and asked several renowned organizational experts to comment on this unusual firm. We asked them to write a short commentary on what the Valve example means for organizational theorists and practitioners. Thankfully, they all accepted, and we are excited to present the results of their thinking in this first “exhibit” in the Organization Zoo.

  8. Assessing Agulhas leakage

    OpenAIRE

    Van Sebille, E.

    2009-01-01

    Agulhas leakage, the water that flows from the Indian Ocean to the Atlantic Ocean, plays an important role in the circulation of the Atlantic Ocean. The magnitude of this flux of warm and saline Indian Ocean water into the much colder and fresher Atlantic Ocean can be related to the strength of the Atlantic meridional overturning circulation, both in numerical ocean models and in paleoceanographic records. However, estimating the magnitude of this Agulhas leakage is not easy. The Agulhas regi...

  9. Annual Check-up

    Science.gov (United States)

    ... Medical Conditions Nutrition & Fitness Emotional Health Annual Check-Up Posted under Health Guides . Updated 7 January 2015. + ... I get ready for my annual medical check-up? If this is your first visit to your ...

  10. Unidirectional valve malfunction by the breakage or malposition of disc - two cases report -

    OpenAIRE

    Lee, Chol; Lee, Kyu Chang; Kim, Hye Young; Kim, Mi Na; Choi, Eun Kyung; Kim, Ji-Sub; Lee, Won Sang; Lee, Myeong Jong; Kim, Hyung Tae

    2013-01-01

    Malfunction of the unidirectional valve in a breathing circuit system may cause hypercapnia from the rebreathing of expired gas, ventilation failure, and barotrauma. Capnography is a useful method for monitoring the integrity of the unidirectional valve. We experienced two cases of malfunction of a unidirectional valve which caused leakage and reverse flow, diagnosed early as a change of the capnographic waveform. One case was caused by expiratory unidirectional valve breakage. The other was ...

  11. Checking Java Programs

    CERN Document Server

    Darwin, Ian

    2007-01-01

    This Short Cut tells you about tools that will improve the quality of your Java code, using checking above and beyond what the standard tools do, including: Using javac options, JUnit and assertions Making your IDE work harder Checking your source code with PMD Checking your compiled code (.class files) with FindBugs Checking your program's run-time behavior with Java PathFinder

  12. Endovascular resection of the native aortic valve before transcatheter aortic valve implantation: state of the art and review.

    Science.gov (United States)

    Navarra, Emiliano; Mosala Nezhad, Zahra; Bollen, Xavier; Gielen, Charles-Edouard; Mastrobuoni, Stefano; De Kerchove, Laurent; Raucent, Benoit; Astarci, Parla

    2016-09-01

    Transcatheter aortic valve implantation was introduced into clinical practice in 2002 as a rescue approach in patients presenting with symptomatic severe aortic stenosis but not eligible for conventional aortic valve replacement. This technique allows implantation of a balloon expandable bioprosthesis without resection of the native aortic valve. Several complications are described as a consequence of the residual highly calcified valve being squeezed against the aortic wall by the stent of the implant. This can result in deformation of the metal stent and paravalvular leakage, risk of occlusion of the coronary ostia, or central and peripheral embolization of valvular debris. To avoid these complications, many authors suggest the possibility to resect and remove the native aortic valve before transcatheter aortic valve implantation. In this field, different authors have described possible techniques and different sources of energy to resect the calcified valve. In this article, we review the development of these experimental techniques and discuss future prospects in this field. PMID:27032472

  13. [Valve-in-valve with Portico valve for a degenerative bioprosthetic surgical valve (Biocor)].

    Science.gov (United States)

    Latini, Roberto Adriano; Testa, Luca; Brambilla, Nedy; Tusa, Maurizio; Bedogni, Francesco

    2016-04-01

    In the last years, a general shift toward the use of surgical bioprosthetic aortic valves rather than mechanical valves with subsequent less use of anticoagulant therapy has been observed. However, bioprosthetic valves have limited durability. Reoperation, the current standard of care for these patients, carries a high surgical risk, especially because patients are elderly and with numerous comorbidities. Recently, transcatheter aortic valve replacement within a failed bioprosthetic valve (valve-in-valve procedure) has proven feasible. We here describe a case of valve-in-valve procedure with a Portico valve placed in a purely insufficient bioprosthetic valve (Biocor). PMID:27093211

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

    Energy Technology Data Exchange (ETDEWEB)

    Wells, Beric E.

    2012-12-21

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

  15. Zero leakage sealings

    Science.gov (United States)

    Kotesovec, Bernhard; Steinrück, Herbert

    2010-11-01

    The piston rod of a reciprocating compressor is sealed with elastic cylindrical sealing elements. Across the sealings the pressure drops from the operating pressure to the ambient pressure. The lubrication gap between the elastic sealing and reciprocating piston rod is studied with the aim to find conditions of a leakage free sealing. The flow in the lubrication gap and the elastic deformation of the sealing are determined simultaneously. The net-flow during one cycle of the reciprocating piston rod is calculated. It turns out that maintaining zero leakage is very sensible. Indeed the outbound flow during out-stroke has to be equal the inbound flow during the in-stroke. By prescribing a special shape of the undeformed sealing zero leakage can be attained - at least theoretically for certain operating conditions. It turns out that temperature dependent material data and a model for cavitation is necessary. The model, its numerical implementation and results will be discussed.

  16. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  17. 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.

  18. Valve's Way

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul; Dobrajska, Magdalena

    2015-01-01

    Puranam and Håkonsson (2015) challenge us to ponder what we as organization design theorists make of Valve’s way (see also Jeppesen, 2008). We believe that Valve, in spite of its radical vision, does not represent a challenge to fundamental organization design theory and that it is questionable...... to what extent it represents a new blueprint for organization design, despite it being consistent with an “egalitarian Zeitgeist” (Puranam, 2014). In fact, managerial authority may be of increasing importance rather than the opposite (Guadalupe, Li, & Wulf, 2015). Thus, Valve is, and will remain...

  19. Excess flow shutoff valve

    Energy Technology Data Exchange (ETDEWEB)

    Kiffer, Micah S.; Tentarelli, Stephen Clyde

    2016-02-09

    Excess flow shutoff valve comprising a valve body, a valve plug, a partition, and an activation component where the valve plug, the partition, and activation component are disposed within the valve body. A suitable flow restriction is provided to create a pressure difference between the upstream end of the valve plug and the downstream end of the valve plug when fluid flows through the valve body. The pressure difference exceeds a target pressure difference needed to activate the activation component when fluid flow through the valve body is higher than a desired rate, and thereby closes the valve.

  20. Vacuum Valve

    CERN Multimedia

    1974-01-01

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

  1. Assessing Agulhas leakage

    NARCIS (Netherlands)

    van Sebille, E.

    2009-01-01

    Agulhas leakage, the water that flows from the Indian Ocean to the Atlantic Ocean, plays an important role in the circulation of the Atlantic Ocean. The magnitude of this flux of warm and saline Indian Ocean water into the much colder and fresher Atlantic Ocean can be related to the strength of the

  2. 40 CFR 53.52 - Leak check test.

    Science.gov (United States)

    2010-07-01

    ..., NIST-traceable. (2) Flow rate measurement adaptor (40 CFR part 50, appendix L, figure L-30) or... valve of the adaptor to seal the flow system. Conduct the external leak check procedure as described in... MONITORING REFERENCE AND EQUIVALENT METHODS Procedures for Testing Physical (Design) and...

  3. WEAR AND SEALING CHARACTERISTICS OF ENGINE VALVE GUIDE

    Institute of Scientific and Technical Information of China (English)

    Qu Shengguan; Xia Wei; Han Lifa; Xiao Zhiyu; Chen Weiping; Li Yuanyuan

    2005-01-01

    A novel powder metallurgy (P/M) material with high wear resistance is developed in order to decrease the wear and lubricant-leakage of a diesel engine valve guide. The friction and wear tests of this material are conducted. It indicates that the wear resistance of the newly developed P/M material has been improved and much better than that of the formerly used alloy steel. Moreover, three different sealing structures are designed and theoretically analyzed with respect to the characteristic of hydrodynamic sealing. Through comparative experiments of component leakage and engine run-in for different valve guide structures, it proves that the structure with a machined sealing groove but not installed with a seal-ring cannot only reduce the specific lubricant consumption (SLC) of cylinder head, but also decrease the wear of valve stem and valve guide.

  4. Aortic valve bypass

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  5. Leakage behind casing

    OpenAIRE

    Khandka, Rupak Kumar

    2007-01-01

    Achieving zonal isolation by cementing annulus space between casing and well bore is an important job in many oil wells. Gas leakage in the annulus has been recognised as a major completion problem in the oil well. A successful cement job results in complete zonal isolation on a permanent basis. To achieve these goals, various factors such as well security, casing centralization, effective mud removal, and gas migration must be considered in the design. The design of the cement must be such t...

  6. Mitral Valve Disease

    Science.gov (United States)

    ... Tricuspid Valve Disease Cardiac Rhythm Disturbances Thoracic Aortic Aneurysm Pediatric and Congenital Heart Disease Heart abnormalities that are ... Transplantation End-stage Lung Disease Adult Lung Transplantation Pediatric Lung ... Aortic Aneurysm Mitral Valve Disease Overview The mitral valve is ...

  7. Automatic shutoff valve

    Science.gov (United States)

    Hawkins, S. F.; Overbey, C. W.

    1980-01-01

    Cellulose-sponge disk absorbs incoming water and expands with enough force to shut valve. When water recedes, valve opens by squeezing sponge dry to its original size. This direct mechanical action is considered more reliable than solenoid valve.

  8. Symbolic model checking APSL

    Institute of Scientific and Technical Information of China (English)

    Wanwei LIU; Ji WANG; Huowang CHEN; Xiaodong MA; Zhaofei WANG

    2009-01-01

    Property specification language (PSL) is a specification language which has been accepted as an industrial standard. In PSL, SEREs are used as additional formula constructs. In this paper, we present a variant of PSL, namely APSL, which replaces SEREs with finite automata. APSL and PSL are of the exactly same expressiveness. Then, we extend the LTL symbolic model checking algorithm to that of APSL, and then present a tableau based APSL verification technique, which can be easily implemented via the BDD based symbolic approach. Moreover, we implement an extension of NuSMV, and this adapted version supports symbolic model checking of APSL. Experimental results show that this variant of PSL can be efficiently verified. Henceforth, symbolic model checking PSL can be carried out by a transformation from PSL to APSL and symbolic model checking APSL.

  9. Check It Out

    Science.gov (United States)

    ... Materials The Healthy Heart Handbook for Women Check it Out Tests That Can Help Protect Your Heart ... years, or more often if your doctor recommends it. Other Tests There also are several tests that ...

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

    NARCIS (Netherlands)

    ten Hallers, E. J. Olivier; Marres, Henri A. M.; van der Houwen, Eduard B.; Jansen, John A.; Rakhorst, Gerhard; Schutte, Harm K.; van Kooten, Theo G.; van Loon, Jan-Paul; Verkerke, Gijsbertus J.

    2006-01-01

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

  11. Adjustable safety relief valve

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, W.L.

    1990-06-12

    This patent describes a pressure relief valve having a relief set pressure. It comprises: a valve body having a fluid inlet and outlet, a spherical, metal valve seat associated with the inlet and a valve member comprising at least a portion of a spherical,metal ball attached to a ball holding element, the valve member being biased against the valve seat and thus providing a metal-to-metal seal preventing the passage of fluids past the valve seat when the fluid pressure in the inlet is below the relief pressure setting of the valve.

  12. Proceedings of EPRI/DOE workshop on nuclear industry valve problems

    International Nuclear Information System (INIS)

    Representatives from 29 nuclear industry organizations (11 valve manufacturers, 4 nuclear steam supply system vendors, 5 utilities, 3 national laboratories, 2 architect/engineering firms, the Department of Energy (DOE), EPRI, and 2 others) attended the workshop. Working sessions on key valves and on valve stem and seat leakage developed the following recommendations: (1) establish a small permanent expert staff to collect, analyze, and disseminate information about nuclear valve problems; (2) perform generic key valve programs for pressurized water reactors and for boiling water reactors, and several plant specific key valve programs, the latter to demonstrate the cost-effectiveness of such studies; (3) confirm the identity of, define, and initiate needed longer term research and development programs dealing with seat and stem leakage; and (4) establish an industry working group to review and advise on these efforts. Separate abstracts were prepared for three papers which are included in the appendix

  13. Goat production check list

    DEFF Research Database (Denmark)

    Henriksen, Jørgen; Nielsen, Mette Benedicte Olaf; Madsen, Jørgen;

    2009-01-01

    This check list, financed by DanChurchAid, highlights all issues should be carefully investigated before investing in distribution of goats and in interventions to assist poor rural communities to improve their livelihood through goat production.......This check list, financed by DanChurchAid, highlights all issues should be carefully investigated before investing in distribution of goats and in interventions to assist poor rural communities to improve their livelihood through goat production....

  14. NHS Health Checks

    OpenAIRE

    Abdalrahman, Bayad; Soljak, Michael

    2014-01-01

    Cardiovascular disease is the leading cause of mortality and morbidity worldwide. In England, the government has adopted a population-wide prevention program for cardiovascular disease, the NHS Health Check program. The program has sparked controversies over the evidence base and feasibility of implementation. We aim to provide an update on the debate and program implementation. In conclusion, the evidence base for the NHS Health Check program has a number of uncertainties and program deliver...

  15. Leakage resilient password systems

    CERN Document Server

    Li, Yingjiu; Deng, Robert H

    2015-01-01

    This book investigates tradeoff between security and usability in designing leakage resilient password systems (LRP) and introduces two practical LRP systems named Cover Pad and ShadowKey. It demonstrates that existing LRP systems are subject to both brute force attacks and statistical attacks and that these attacks cannot be effectively mitigated without sacrificing the usability of LRP systems. Quantitative analysis proves that a secure LRP system in practical settings imposes a considerable amount of cognitive workload unless certain secure channels are involved. The book introduces a secur

  16. 2D DIGITAL SIMPLIFIED FLOW VALVE

    Institute of Scientific and Technical Information of China (English)

    Ruan Jian; Li Sheng; Pei Xiang; Burton R; Ukrainetz P; Bitner D

    2004-01-01

    The 2D digital simplified flow valve is composed of a pilot-operated valve designed with both rotary and linear motions of a single spool,and a stepper motor under continual control.How the structural parameters affect the static and dynamic characteristics of the valve is first clarified and a criterion for stability is presented.Experiments are designed to test the performance of the valve.It is necessary to establish a balance between the static and dynamic characteristics in deciding the structural parameters.Nevertheless,it is possible to maintain the dynamic response at a fairly high level,while keeping the leakage of the pilot stage at an acceptable level.One of the features of the digital valve is stage control.In stage control the nonlinearities,such as electromagnetic saturation and hysteresis,are greatly reduced.To a large extent the dynamic response of the valve is decided by the executing cycle of the control algorithm.

  17. SRAM standby leakage decoupling analysis for different leakage reduction techniques

    Institute of Scientific and Technical Information of China (English)

    Dong Qing; Lin Yinyin

    2013-01-01

    SRAM standby leakage reduction plays a pivotal role in minimizing the power consumption of application processors.Generally,four kinds of techniques are often utilized for SRAM standby leakage reduction:Vdd lowering (VDDL),Vss rising (VSSR),BL floating (BLF) and reversing body bias (RBB).In this paper,we comprehensively analyze and compare the reduction effects of these techniques on different kinds of leakage.It is disclosed that the performance of these techniques depends on the leakage composition of the SRAM cell and temperature.This has been verified on a 65 nm SRAM test macro.

  18. Blast Valve Design and Related Studies : A Review

    Directory of Open Access Journals (Sweden)

    P. K. Sharma

    2016-04-01

    Full Text Available The protective structures required for performing critical operations are vulnerable to the blast and shock loads of advanced weapons. A blast valve is an important component of such structures for ventilation during normal conditions and for protection from blast/ shock during explosion. In this paper, various aspects of blast valve design and related studies are briefly reviewed. The concept and effects of blast wave, blast impact, numerical modelling and deformation of circular plate (one of the critical components of blast valve have been discussed. The merits and demerits of sensing mechanisms viz. remote and direct sensing are discussed. The leakage of blast pressure during finite closing period of the valve (one of the critical problems and the shock tube as a major experimental facility for testing of blast valves are briefly discussed.

  19. Valve-in-valve-in-valve: Treating endocarditis of a transcatheter heart valve.

    Science.gov (United States)

    Nguyen, Caroline; Cheong, Adrian P; Himbert, Dominique

    2015-10-01

    Transcatheter heart valve endocarditis is a rare, but life threatening complication. We describe the case of a patient who was successfully treated by transcatheter aortic valve-in-valve-in-valve replacement with a favorable 1-year outcome, despite severe early complications.

  20. 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.

  1. Microfluidic sieve valves

    Science.gov (United States)

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

    2015-01-13

    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  2. Remote actuated valve implant

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-10

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

  3. CMM Interim Check (U)

    Energy Technology Data Exchange (ETDEWEB)

    Montano, Joshua Daniel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-23

    Coordinate Measuring Machines (CMM) are widely used in industry, throughout the Nuclear Weapons Complex and at Los Alamos National Laboratory (LANL) to verify part conformance to design definition. Calibration cycles for CMMs at LANL are predominantly one year in length. Unfortunately, several nonconformance reports have been generated to document the discovery of a certified machine found out of tolerance during a calibration closeout. In an effort to reduce risk to product quality two solutions were proposed – shorten the calibration cycle which could be costly, or perform an interim check to monitor the machine’s performance between cycles. The CMM interim check discussed makes use of Renishaw’s Machine Checking Gauge. This off-the-shelf product simulates a large sphere within a CMM’s measurement volume and allows for error estimation. Data was gathered, analyzed, and simulated from seven machines in seventeen different configurations to create statistical process control run charts for on-the-floor monitoring.

  4. Valve-in-Valve Replacement Using a Sutureless Aortic Valve

    Science.gov (United States)

    Dohmen, Pascal M.; Lehmkuhl, Lukas; Borger, Michael A.; Misfeld, Martin; Mohr, Friedrich W.

    2016-01-01

    Patient: Female, 61 Final Diagnosis: Tissue degeneration Symptoms: Dyspnea Medication: — Clinical Procedure: Redo valve replacement Specialty: Surgery Objective: Rare disease Background: We present a unique case of a 61-year-old female patient with homograft deterioration after redo surgery for prosthetic valve endocarditis with root abscess. Case Report: The first operation was performed for type A dissection with root, arch, and elephant trunk replacement of the thoracic aorta. The present re-redo surgery was performed as valve-in-valve with a sutureless aortic biopros-thesis. The postoperative course was uneventful and the patient was discharged on day 6. Conclusions: The current case report demonstrates that sutureless bioprostheses are an attractive option for surgical valve-in-valve procedures, which can reduce morbidity and mortality. PMID:27694795

  5. Design considerations for a micromachined proportional control valve

    NARCIS (Netherlands)

    Groen, Maarten S.; Brouwer, Dannis M.; Wiegerink, Remco J.; Lötters, Joost C.

    2012-01-01

    Precise mass flow control is an essential requirement for novel, small-scale fluidic systems. However, a small-volume, low-leakage proportional control valve for minute fluid flows has not yet been designed or manufactured. A survey is therefore made of the primary design considerations of a microma

  6. Partial model checking

    DEFF Research Database (Denmark)

    Andersen, Henrik Reif

    1995-01-01

    A major obstacle in applying finite-state model checking to the verification of large systems is the combinatorial explosion of the state space arising when many loosely coupled parallel processes are considered. The problem also known as the state-explosion problem has been attacked from various...... sides. This paper presents a new approach based on partial model checking where parts of the concurrent system are gradually removed while transforming the specification accordingly. When the intermediate specifications constructed in this manner can be kept small, the state-explosion problem is avoided...

  7. Check My School

    OpenAIRE

    SHKABATUR, Jennifer

    2012-01-01

    Check My School (CMS) is a community monitoring project that aims to promote transparency and social accountability in the Philippine education sector by tracking the provision of services in public schools. The project uses a blended approach, which combines on-the-ground community monitoring with the use of information and communication technology (ICT). CMS had been initiated and design...

  8. Checking BEBC superconducting magnet

    CERN Multimedia

    1974-01-01

    The superconducting coils of the magnet for the 3.7 m Big European Bubble Chamber (BEBC) had to be checked, see Annual Report 1974, p. 60. The photo shows a dismantled pancake. By December 1974 the magnet reached again the field design value of 3.5 T.

  9. Checking for Ketones

    Science.gov (United States)

    ... by Mail Close www.diabetes.org > Living With Diabetes > Treatment and Care > Blood Glucose Testing Share: Print Page Text Size: ... glucose-and-a1c, In this section Living With Diabetes Treatment and Care Blood Glucose Testing Checking Your Blood Glucose A1C ...

  10. Leakage tests on the EURATOM LCT coil

    International Nuclear Information System (INIS)

    The acceptance tests at ambient temperature on the superconducting LCT coil, which was developed and manufactured by Siemens, were successful. The size and complexity of the coil imposed high demands on in-process quality control. The helium leakage tests and integrity of the test procedures were particularly important. Leaks were detected at an early stage by means of inspection and test plans and were repaired at no great expense. Unsuitable components were detected by routine tests on critical parts, such as belows, current feed-throughs and potential separators under simulated operating conditions (cycles up to 4 K and 24 bar). The procedure for checking for helium leaks was selected such that the permissible leak rate could be proved within the minimum possible time. 500 m hollow conductors were tested using a specially developed procedure. Over 500 individual inspections and tests were performed using more than 20 different test set-ups. (orig.)

  11. Reynolds shear stress for textile prosthetic heart valves in relation to fabric design.

    Science.gov (United States)

    Bark, David L; Yousefi, Atieh; Forleo, Marcio; Vaesken, Antoine; Heim, Frederic; Dasi, Lakshmi P

    2016-07-01

    The most widely implanted prosthetic heart valves are either mechanical or bioprosthetic. While the former suffers from thrombotic risks, the latter suffers from a lack of durability. Textile valves, alternatively, can be designed with durability and to exhibit hemodynamics similar to the native valve, lowering the risk for thrombosis. Deviations from native valve hemodynamics can result in an increased Reynolds Shear Stress (RSS), which has the potential to instigate hemolysis or shear-induced thrombosis. This study is aimed at characterizing flow in multiple textile valve designs with an aim of developing a low profile valve. Valves were created using a shaping process based on heating a textile membrane and placed within a left heart simulator. Turbulence and bulk hemodynamics were assessed through particle imaging velocimetry, along with flow and pressure measurements. Overall, RSS was reduced for low profile valves relative to high profile valves, but was otherwise similar among low profile valves involving different fabric designs. However, leakage was found in 3 of the 4 low profile valve designs driving the fabric design for low profile valves. Through textile design, low profile valves can be created with favorable hemodynamics. PMID:26919564

  12. Reynolds shear stress for textile prosthetic heart valves in relation to fabric design.

    Science.gov (United States)

    Bark, David L; Yousefi, Atieh; Forleo, Marcio; Vaesken, Antoine; Heim, Frederic; Dasi, Lakshmi P

    2016-07-01

    The most widely implanted prosthetic heart valves are either mechanical or bioprosthetic. While the former suffers from thrombotic risks, the latter suffers from a lack of durability. Textile valves, alternatively, can be designed with durability and to exhibit hemodynamics similar to the native valve, lowering the risk for thrombosis. Deviations from native valve hemodynamics can result in an increased Reynolds Shear Stress (RSS), which has the potential to instigate hemolysis or shear-induced thrombosis. This study is aimed at characterizing flow in multiple textile valve designs with an aim of developing a low profile valve. Valves were created using a shaping process based on heating a textile membrane and placed within a left heart simulator. Turbulence and bulk hemodynamics were assessed through particle imaging velocimetry, along with flow and pressure measurements. Overall, RSS was reduced for low profile valves relative to high profile valves, but was otherwise similar among low profile valves involving different fabric designs. However, leakage was found in 3 of the 4 low profile valve designs driving the fabric design for low profile valves. Through textile design, low profile valves can be created with favorable hemodynamics.

  13. ENERGY EFFICIENT AND SAFE VALVE TESTING UNIT USING WIRELESS TECHNOLOGIES

    Directory of Open Access Journals (Sweden)

    V. Dhivya

    2013-04-01

    Full Text Available The valve testing unit is a high pressure test equipment to test the valve manufactured in industries. Valves are tested to ensure that they sustain high pressure in the range of 10000 to 15000 PSI for the required amount of time without any leakage. It has few drawbacks such as inefficient usage of power, fatal accidents due to the proximity of the users with the testing unit to note the valve pressure during operation. It is much dangerous for the industry personnel to note the valve pressure for every minute during operation. There are chances of bolts fitted in the valve thrown away due to the issues in the bolt fittings and the immense pressure inside the valve. Therefore in order to avoid fatal accidents andto improve the industrial safety an efficient valve testing unit is designed and developed using ZigBee wireless transmission technology. The proposed efficient pressure monitoring unit uses emerging technologies like ZigBee, RFID along with ARM 7 processor. The proposed system uses LabVIEW software to develop the monitoring unit in PC. ZigBee wireless transmission technology is used for remote monitoring of valve pressure for every minute. RFID module is used for uniquely identifying the valve and to track the test results. The proposed unit saves energy by sending a signal to turn off the air driven booster pump once the prescribed pressure level is reached. Theproposed unit also indicates the oil level of the test unit which avoids the manual intervention to verify the oil level and also detects issues in the bolts fitted in the valve by using a distance sensor which is to avoid fatal accidents by stopping the valve testing unit.

  14. Duct Leakage Repeatability Testing

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherman, Max [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-08-01

    The purpose of this report is to evaluate the repeatability of the three most significant measurement techniques for duct leakage using data from the literature and recently obtained field data. We will also briefly discuss the first two factors. The main question to be answered by this study is to determine if differences in the repeatability of these tests methods is sufficient to indicate that any of these methods is so poor that it should be excluded from consideration as an allowed procedure in codes and standards. The three duct leak measurement methods assessed in this report are the two duct pressurization methods that are commonly used by many practitioners and the DeltaQ technique. These are methods B, C and A, respectively of the ASTM E1554 standard. Although it would be useful to evaluate other duct leak test methods, this study focused on those test methods that are commonly used and are required in various test standards, such as BPI (2010), RESNET (2014), ASHRAE 62.2 (2013), California Title 24 (CEC 2012), DOE Weatherization and many other energy efficiency programs.

  15. Multifamily Envelope Leakage Model

    Energy Technology Data Exchange (ETDEWEB)

    Faakye, Omari [Consortium for Advanced Residential Buildings, Norwalk, CT (United States); Griffiths, Dianne [Consortium for Advanced Residential Buildings, Norwalk, CT (United States)

    2015-05-08

    “The cost for blower testing is high, because it is labor intensive, and it may disrupt occupants in multiple units. This high cost and disruption deter program participants, and dissuade them from pursuing energy improvements that would trigger air leakage testing, such as improvements to the building envelope.” This statement found in a 2012 report by Heschong Mahone Group for several California interests emphasizes the importance of reducing the cost and complexity of blower testing in multifamily buildings. Energy efficiency opportunities are being bypassed. The cost of single blower testing is on the order of $300. The cost for guarded blower door testing—the more appropriate test for assessing energy savings opportunities—could easily be six times that, and that’s only if you have the equipment and simultaneous access to multiple apartments. Thus, the proper test is simply not performed. This research seeks to provide an algorithm for predicting the guarded blower door test result based upon a single, total blower door test.

  16. Duct Leakage Repeatability Testing

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherman, Max [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-01-01

    Duct leakage often needs to be measured to demonstrate compliance with requirements or to determine energy or Indoor Air Quality (IAQ) impacts. Testing is often done using standards such as ASTM E1554 (ASTM 2013) or California Title 24 (California Energy Commission 2013 & 2013b), but there are several choices of methods available within the accepted standards. Determining which method to use or not use requires an evaluation of those methods in the context of the particular needs. Three factors that are important considerations are the cost of the measurement, the accuracy of the measurement and the repeatability of the measurement. The purpose of this report is to evaluate the repeatability of the three most significant measurement techniques using data from the literature and recently obtained field data. We will also briefly discuss the first two factors. The main question to be answered by this study is to determine if differences in the repeatability of these tests methods is sufficient to indicate that any of these methods is so poor that it should be excluded from consideration as an allowed procedure in codes and standards.

  17. Design of a New Type of Distribution Valve for Hydraulic Breaker and Analysis of Energy Consumption

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Energy consumed by distribution valves causes an energy loss for the output energy of hydraulic breakers, which has a significant influence on its efficiency. A new type of distribution valve used for hydraulic breakers, designed to reduce energy consumption, is analyzed on the basis of the operating principle and energy loss of the current distribution valve. The new distribution valve adopts a cone valve and the optimization technique of unequal open degree for the valve port. Theoretical calculations and analyses have proven that the new distribution valve can reduce energy loss by 9.0127J, or energy consumption by 31%, during an impact cycle and the efficiency of the hydraulic breaker can be raised by 4.5%. It has the following characteristics: little leakage, little pressure loss and low energy consumption.

  18. Check Verbraucherpolitik und Verbraucherbeteiligung

    DEFF Research Database (Denmark)

    Hagen, Kornelia; Micklitz, Hans-W.; Oehler, Andreas;

    2013-01-01

    The paper discusses the opportunities for an empirically grounded decision support system as an instrument for independent and scientifically based consumer policy consulting. To date, consumer policy is dominated by the information paradigm and the leitbild of the rational, sovereign...... and information-seeking consumer. Yet, both everyday practice and research in behavioural economics show that this view lacks empirical ground. In fact, there are different consumer types and different forms of rationalities at work. Effective consumer policy making should be based on the empirically revealed...... an empirically based “Check Consumer Policy and Consumer Participation” as a systematic decision and evaluation tool for policy makers. This check should be independent from the government and should be grounded on an empirical view of the consumer. Consumer policy tools should be tested with real consumers...

  19. Quench tank in-leakage diagnosis at St. Lucie

    Energy Technology Data Exchange (ETDEWEB)

    Price, J.E.; Au-Yang, M.K.; Beckner, D.A.; Vickery, A.N.

    1996-12-01

    In February 1995, leakage into the quench tank of the St. Lucie Nuclear Station Unit 1 was becoming an operational concern. This internal leak resulted in measurable increases in both the temperature and level of the quench tank water, and was so severe that, if the trend continued, plant shut down would be necessary. Preliminary diagnosis based on in-plant instrumentation indicated that any one of 11 valves might be leaking into the quench tank. This paper describes the joint effort by two teams of engineers--one from Florida Power & Light, the other from Framatome Technologies--to identify the sources of the leak, using the latest technology developed for valve diagnosis.

  20. Mitral valve prolapse

    Science.gov (United States)

    ... seen with some connective tissue disorders such as Marfan syndrome and other rare genetic disorders. Symptoms Many ... 66. Read More Atrial septal defect (ASD) Endocarditis Marfan syndrome Mitral valve surgery - minimally invasive Mitral valve ...

  1. Aortic Valve Disease

    Science.gov (United States)

    ... valve opens when the left ventricle squeezes to pump out blood, and closes in between heart beats to keep ... the left ventricle has to work harder to pump blood out through the valve. To do this extra ...

  2. Aerodynamic Shutoff Valve

    Science.gov (United States)

    Horstman, Raymond H.

    1992-01-01

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

  3. Transcatheter Pulmonary Valve Replacement

    OpenAIRE

    Ghawi, Hani; Kenny, Damien; Hijazi, Ziyad M.

    2012-01-01

    Transcatheter pulmonary valve replacement (tPVR) has evolved into a viable alternative to surgical conduit or bioprosthetic valve replacement. This procedure has paved the way for a more advanced approach to congenital and structural interventional cardiology. Although many successes have been noted, there are still a number of challenges with this procedure, including large delivery systems, the need for a conduit or a bioprosthetic valve as a landing zone for the valve, optimal timing of th...

  4. Isolated Pulmonary Valve Endocarditis

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Hatamizadeh

    2009-06-01

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

  5. Heart Valve Diseases

    Science.gov (United States)

    Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

  6. Check, check, double check: checking the autopilot causes distrust : Experimental studies on the effects of compulsive perseveration

    NARCIS (Netherlands)

    Dek, E.C.P.

    2015-01-01

    Obsessive-compulsive disorder (OCD) is characterized by persistent doubt. The majority of patients with OCD engage in repeated checking to reduce these feelings of uncertainty. However, numerous studies demonstrated that repetitive behavior ironically increases uncertainty: perseverative checking in

  7. Checking Model Transformation Refinement

    OpenAIRE

    Büttner, Fabian; Egea, Marina; Guerra, Esther; Lara, Juan De

    2013-01-01

    The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-38883-5_15 Proceedings of 6th International Conference, ICMT 2013, Budapest, Hungary, June 18-19, 2013 Refinement is a central notion in computer science, meaning that some artefact S can be safely replaced by a refinement R, which preserves S’s properties. Having available techniques and tools to check transformation refinement would enable (a) the reasoning on whether a transformation correctly impl...

  8. 49 CFR 178.338-8 - Pressure relief devices, piping, valves, and fittings.

    Science.gov (United States)

    2010-10-01

    ...) Pipe joints must be threaded, welded or flanged. If threaded pipe is used, the pipe and fittings must... connection to that coil must be provided with a valve or check valve as close to the tank shell as practicable to prevent the loss of vapor from the tank in case of damage to the coil. The liquid connection...

  9. Safety of the adjustable pressure ventricular valve in magnetic resonance imaging: problems and solutions

    Energy Technology Data Exchange (ETDEWEB)

    Fransen, P.; Thauvoy, C. (Clinique Universitaire St. Luc, Brussels (Belgium). Neurosurgery Service); Dooms, G. (Clinique Universitaire St. Luc, Brussels (Belgium). Neuroradiology Service)

    1992-11-01

    We performed magnetic resonance imaging in 30 patients with hydrocephalus with Sophy adjustable pressure valves (PAVS). A pressure check following the MRI study showed a significant proportion with pressure valve changes, which could easily be readjusted by percutaneous manipulation. The value of the PAVS and its safety during MRI examinations are discussed. (orig.).

  10. Main Oxidizer Valve Design

    Science.gov (United States)

    Addona, Brad; Eddleman, David

    2015-01-01

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

  11. Bounded Model Checking of CTL

    Institute of Scientific and Technical Information of China (English)

    Zhi-Hong Tao; Cong-Hua Zhou; Zhong Chen; Li-Fu Wang

    2007-01-01

    Bounded Model Checking has been recently introduced as an efficient verification method for reactive systems.This technique reduces model checking of linear temporal logic to propositional satisfiability.In this paper we first present how quantified Boolean decision procedures can replace BDDs.We introduce a bounded model checking procedure for temporal logic CTL* which reduces model checking to the satisfiability of quantified Boolean formulas.Our new technique avoids the space blow up of BDDs, and extends the concept of bounded model checking.

  12. Importance of pressure reducing valves (PRVs) in water supply networks.

    Science.gov (United States)

    Signoreti, R. O. S.; Camargo, R. Z.; Canno, L. M.; Pires, M. S. G.; Ribeiro, L. C. L. J.

    2016-08-01

    Challenged with the high rate of leakage from water supply systems, these managers are committed to identify control mechanisms. In order to standardize and control the pressure Pressure Reducing Valves (VRP) are installed in the supply network, shown to be more effective and provide a faster return for the actual loss control measures. It is known that the control pressure is while controlling the occurrence of leakage. Usually the network is sectored in areas defined by pressure levels according to its topography, once inserted the VRP in the same system will limit the downstream pressure. This work aims to show the importance of VRP as loss reduction for tool.

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

    Energy Technology Data Exchange (ETDEWEB)

    Schlereth, J.R.; Pennington, D.

    1996-12-01

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

  14. Valve selection in aortic valve endocarditis

    Science.gov (United States)

    Zubrytska, Yana

    2016-01-01

    Aortic prosthetic valve endocarditis (PVE) is a potentially life-threatening disease. Mortality and incidence of infective endocarditis have been reduced in the past 30 years. Medical treatment of aortic PVE may be successful in patients who have a prompt response after antibiotic treatment and who do not have prosthetic dysfunction. In advanced stages, antibiotic therapy alone is insufficient to control the disease, and surgical intervention is necessary. Surgical treatment may be lifesaving, but it is still associated with considerable morbidity and mortality. The aim of surgery is to perform a radical excision of all infected and necrotic tissue, reconstruction of the left ventricle outflow tract, and replacement of the aortic valve. There is no unanimous consensus on which is the optimal prosthesis to implant in this context, and several surgical techniques have been suggested. We aim to analyze the efficacy of the surgical treatment and discuss the issue of valve selection in patients with aortic valve endocarditis.

  15. Optimization of Control Logic and Operation of the Steam Pump Recirculation Valve%汽泵再循环阀控制逻辑和运行操作优化

    Institute of Scientific and Technical Information of China (English)

    杨宁

    2016-01-01

    The recirculating valve of steam pump of the 600MW coal‐fired units has serious inner leakage in the operating system which will cause high energy consumption and endanger the feed water system .After the dis‐integration check ,we discovered that the recirculating valve was badly damaged by frequently opens and clo‐ses .Through optimizing the control logic of the recirculating valve and the corresponding operation ,it is good to resolve the problem and ensure the equipment safety .%讲述了600 M W燃煤机组的汽泵再循环阀在运行过程中内漏严重,影响给水系统运行安全以及造成汽泵能耗损失;对再循环阀进行解体检查分析,确定汽泵运行再循环阀的频繁开启造成再循环阀吹损严重。通过对汽泵再循环阀的控制逻辑进行优化以及对应的运行操作优化,很好地解决了汽泵再循环阀吹损严重这个问题,保证了设备安全。

  16. A computer code for seismic qualification of nuclear service valves

    International Nuclear Information System (INIS)

    The computer code, CERTIVALVE, has been developed for detailed frequency, seismic stress, and deformation analysis of nuclear service valves. It is an expedient means of analyzing, designing, and qualifying nuclear service valves for dynamic loads. The program is designed to be applicable to virtually all types of ASME Class 1, 2, and 3 valves, including gate, globe, disk, ball, safety-relief, diaphragm, and butterfly valves. It can evaluate valves of nearly all major manufacturers both foreign and domestic. CERTIVALVE computes all natural frequencies of any valve up to 40 Hertz (or higher if the user desires). The program constructs a multi-degree-offreedom (MDOF) finite element model which is used in the eigenvalue (natural frequency) solution. CERTIVALVE also computes the maximum allowable acceleration capacity of any valve on the basis of user-supplied allowable stress limits and the geometric and material properties of the valve components. The worst spatial orientation of the valve is assumed. The maximum allowable resultant is reported in terms of a multiple of weight (that is, in values of g) for each valve component. The valve components evaluated include the non-pressure retaining yoke structure for prismatic, nonprismatic, and curved sections; the yoke-bonnet junction for bolted, clamped and bossed connection details; the bonnet and body sections for various geometric cross sections; and the body-bonnet junction for both bolted-gasket and threaded connections. Finally, the program also performs an operability deformation analysis to check that stem binding is precluded. The evaluation procedures are performed in accordance with included codes and standards. The theoretical development of the program is provided and examples of the program options are presented

  17. Protocol for relative hydrodynamic assessment of tri-leaflet polymer valves.

    Science.gov (United States)

    Ramaswamy, Sharan; Salinas, Manuel; Carrol, Rob; Landaburo, Karla; Ryans, Xavier; Crespo, Cynthia; Rivero, Ailyn; Al-Mousily, Faris; DeGroff, Curt; Bleiweis, Mark; Yamaguchi, Hitomi

    2013-01-01

    Limitations of currently available prosthetic valves, xenografts, and homografts have prompted a recent resurgence of developments in the area of tri-leaflet polymer valve prostheses. However, identification of a protocol for initial assessment of polymer valve hydrodynamic functionality is paramount during the early stages of the design process. Traditional in vitro pulse duplicator systems are not configured to accommodate flexible tri-leaflet materials; in addition, assessment of polymer valve functionality needs to be made in a relative context to native and prosthetic heart valves under identical test conditions so that variability in measurements from different instruments can be avoided. Accordingly, we conducted hydrodynamic assessment of i) native (n = 4, mean diameter, D = 20 mm), ii) bi-leaflet mechanical (n= 2, D = 23 mm) and iii) polymer valves (n = 5, D = 22 mm) via the use of a commercially available pulse duplicator system (ViVitro Labs Inc, Victoria, BC) that was modified to accommodate tri-leaflet valve geometries. Tri-leaflet silicone valves developed at the University of Florida comprised the polymer valve group. A mixture in the ratio of 35:65 glycerin to water was used to mimic blood physical properties. Instantaneous flow rate was measured at the interface of the left ventricle and aortic units while pressure was recorded at the ventricular and aortic positions. Bi-leaflet and native valve data from the literature was used to validate flow and pressure readings. The following hydrodynamic metrics were reported: forward flow pressure drop, aortic root mean square forward flow rate, aortic closing, leakage and regurgitant volume, transaortic closing, leakage, and total energy losses. Representative results indicated that hydrodynamic metrics from the three valve groups could be successfully obtained by incorporating a custom-built assembly into a commercially available pulse duplicator system and subsequently, objectively compared to provide

  18. Water Hydraulic 2/2 Directional Valve with Plane Piston Structure

    Institute of Scientific and Technical Information of China (English)

    GONG Yongjun; YANG Huayong; WANG Zuwen

    2009-01-01

    Due to the fire resistance and environmental compatibility, using water as the working fluid in hydraulic circuits is receiving an increasing attention by both manufactures and users. This hydraulic directional valve is developed. When new water hydraulic directional valve is designed and manufactured, this paper introduces a water hydraulic 2/2 directional valve and its principle. The valve is composed of a hydraulically operated seat valve and a magnetic 3/2 direction valve. Aimed at the serious leakage and impact generating easily in reversing suddenly, an improved structure of water space seal is changed to direct seal, compaction force between main valve spool and main valve pocket was logically designed and damper in pilot valve port is matched with sensitive cavity in main valve. From the view of flow control, the methods of cavitation resistance of the directional water hydraulic valve are investigated. The computational fluid dynamics approaches are applied to obtain static pressure distributions and cavitation images in the channel of the main stage of the valve with two kinds of structure. The results show that the method of optimized spout can effectively restrain cavitation. The work provides some useful reference for developing water hydraulic control valve with the Dower noise and lower vibration. Meantime, the structural parameters are optimized on the basis of information obtained from simulation. Static test, dynamic test and life test are accomplished, and the results show that the water hydraulic directional valve possesses good property, its pressure loss is 1.1 MPa lower, switching time is shorter than 0.025 s, and its strike crest is 0.8 MPa lower. The valve possess fine dynamic performance with the characteristic rapidly action and lower implusion.

  19. JenaValve.

    Science.gov (United States)

    Treede, Hendrik; Rastan, Ardawan; Ferrari, Markus; Ensminger, Stephan; Figulla, Hans-Reiner; Mohr, Friedrich-Wilhelm

    2012-09-01

    The JenaValve is a next-generation TAVI device which consists of a well-proven porcine root valve mounted on a low-profile nitinol stent. Feeler guided positioning and clip fixation on the diseased leaflets allow for anatomically correct implantation of the device without rapid pacing. Safety and efficacy of transapical aortic valve implantation using the JenaValve were evaluated in a multicentre prospective study that showed good short and midterm results. The valve was CE-mark released in Europe in September 2011. A post-market registry ensures on-going and prospective data collection in "real-world" patients. The transfemoral JenaValve delivery system will be evaluated in a first-in-man study in the near future. PMID:22995119

  20. Transcatheter aortic valve implantation in failed bioprosthetic surgical valves

    DEFF Research Database (Denmark)

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

    2014-01-01

    IMPORTANCE: Owing to a considerable shift toward bioprosthesis implantation rather than mechanical valves, it is expected that patients will increasingly present with degenerated bioprostheses in the next few years. Transcatheter aortic valve-in-valve implantation is a less invasive approach...... for patients with structural valve deterioration; however, a comprehensive evaluation of survival after the procedure has not yet been performed. OBJECTIVE: To determine the survival of patients after transcatheter valve-in-valve implantation inside failed surgical bioprosthetic valves. DESIGN, SETTING......, AND PARTICIPANTS: Correlates for survival were evaluated using a multinational valve-in-valve registry that included 459 patients with degenerated bioprosthetic valves undergoing valve-in-valve implantation between 2007 and May 2013 in 55 centers (mean age, 77.6 [SD, 9.8] years; 56% men; median Society of Thoracic...

  1. Model Checking as Static Analysis

    DEFF Research Database (Denmark)

    Zhang, Fuyuan

    Both model checking and static analysis are prominent approaches to detecting software errors. Model Checking is a successful formal method for verifying properties specified in temporal logics with respect to transition systems. Static analysis is also a powerful method for validating program...... properties which can predict safe approximations to program behaviors. In this thesis, we have developed several static analysis based techniques to solve model checking problems, aiming at showing the link between static analysis and model checking. We focus on logical approaches to static analysis......-calculus can be encoded as the intended model of SFP. Our research results have strengthened the link between model checking and static analysis. This provides a theoretical foundation for developing a unied tool for both model checking and static analysis techniques....

  2. Early localization of containment leakage during an accident

    International Nuclear Information System (INIS)

    In case of an accident in a nuclear plant, checking the containment leaktightness would be a fundamental step for the diagnosis and prognosis of the radiological consequences. Significant help in this task can be provided by softwares. For that purpose, the French Atomic Energy Commission (CEA) is developing an expert system which can provide early in the accident a classification of the possible leakage paths and help understanding the necessary corrections which have to be undertaken by the utility. This software will be used at the Emergency Technical Center of the CEA. Its basic principles are described in this paper

  3. [Modern mitral valve surgery].

    Science.gov (United States)

    Bothe, W; Beyersdorf, F

    2016-04-01

    At the beginning of the 20th century, Cutler and Levine performed the first successful surgical treatment of a stenotic mitral valve, which was the only treatable heart valve defect at that time. Mitral valve surgery has evolved significantly since then. The introduction of the heart-lung machine in 1954 not only reduced the surgical risk, but also allowed the treatment of different mitral valve pathologies. Nowadays, mitral valve insufficiency has become the most common underlying pathomechanism of mitral valve disease and can be classified into primary and secondary mitral insufficiency. Primary mitral valve insufficiency is mainly caused by alterations of the valve (leaflets and primary order chords) itself, whereas left ventricular dilatation leading to papillary muscle displacement and leaflet tethering via second order chords is the main underlying pathomechanism for secondary mitral valve regurgitation. Valve reconstruction using the "loop technique" plus annuloplasty is the surgical strategy of choice and normalizes life expectancy in patients with primary mitral regurgitation. In patients with secondary mitral regurgitation, implanting an annuloplasty is not superior to valve replacement and results in high rates of valve re-insufficiency (up to 30 % after 3 months) due to ongoing ventricular dilatation. In order to improve repair results in these patients, we add a novel subvalvular technique (ring-noose-string) to the annuloplasty that aims to prevent ongoing ventricular remodeling and re-insufficiency. In modern mitral surgery, a right lateral thoracotomy is the approach of choice with excellent repair and cosmetic results. PMID:26907868

  4. Air-Leakage Control Manual.

    Energy Technology Data Exchange (ETDEWEB)

    Maloney, Jim; Washington State Energy Office; United States. Bonneville Power Administration.

    1991-05-01

    This manual is for builders and designers who are interested in building energy-efficient homes. The purpose of the manual is to provide the how and why'' of controlling air leakage by means of a system called the Simple Caulk and Seal'' (SIMPLE{center dot}CS) system. This manual provides an overview of the purpose and contents of the manual; It discusses the forces that affect air leakage in homes and the benefits of controlling air leakage. Also discussed are two earlier approaches for controlling air leakage and the problems with these approaches. It describes the SIMPLE-{center dot}CS system. It outlines the standard components of the building envelope that require sealing and provides guidelines for sealing them. It outlines a step-by-step procedure for analyzing and planning the sealing effort. The procedure includes (1) identifying areas to be sealed, (2) determining the most effective and convenient stage of construction in which to do the sealing, and (3) designating the appropriate crew member or trade to be responsible for the sealing.

  5. Air-leakage control manual

    Energy Technology Data Exchange (ETDEWEB)

    Maloney, J. [Washington State Energy Office, Olympia, WA (United States)

    1991-05-01

    This manual is for builders and designers who are interested in building energy-efficient homes. The purpose of the manual is to provide the ``how and why`` of controlling air leakage by means of a system called the ``Simple Caulk and Seal`` (SIMPLE{center_dot}CS) system. This manual provides an overview of the purpose and contents of the manual; It discusses the forces that affect air leakage in homes and the benefits of controlling air leakage. Also discussed are two earlier approaches for controlling air leakage and the problems with these approaches. It describes the SIMPLE-{center_dot}CS system. It outlines the standard components of the building envelope that require sealing and provides guidelines for sealing them. It outlines a step-by-step procedure for analyzing and planning the sealing effort. The procedure includes (1) identifying areas to be sealed, (2) determining the most effective and convenient stage of construction in which to do the sealing, and (3) designating the appropriate crew member or trade to be responsible for the sealing.

  6. Heimlich valve and pneumothorax

    OpenAIRE

    Gogakos, Apostolos; Barbetakis, Nikolaos; Lazaridis, George; Papaiwannou, Antonis; Karavergou, Anastasia; Lampaki, Sofia; Baka, Sofia; Mpoukovinas, Ioannis; Karavasilis, Vasilis; Kioumis, Ioannis; Pitsiou, Georgia; Katsikogiannis, Nikolaos; Tsakiridis, Kosmas; Rapti, Aggeliki; Trakada, Georgia

    2015-01-01

    The Heimlich valve is a small one-way valve used for chest drainage that empties into a flexible collection device and prevents return of gases or fluids into the pleural space. The Heimlich valve is less than 13 cm (5 inches) long and facilitates patient ambulation. Currently there are several systems in the market. It can be used in many patients instead of a traditional water seal drainage system. The Heimlich chest drainage valve was developed so that the process of draining the pleural c...

  7. Biological heart valves.

    Science.gov (United States)

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

    2013-10-01

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

  8. 14 CFR 135.339 - Initial and transition training and checking: Check airmen (aircraft), check airmen (simulator).

    Science.gov (United States)

    2010-01-01

    ... checking: Check airmen (aircraft), check airmen (simulator). 135.339 Section 135.339 Aeronautics and Space... and checking: Check airmen (aircraft), check airmen (simulator). (a) No certificate holder may use a... an aircraft, in a flight simulator, or in a flight training device. This paragraph applies...

  9. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... opens freely when the heart contracts. On the right, we see a picture of the aortic valve ... the aortic valve because the probe is sitting right behind the aortic valve. Lots of patients on ...

  10. 3-D Transient CFD Model For A Rolling Piston Compressor With A Dynamic Reed Valve

    OpenAIRE

    Ding, Hui; Gao, Haiyang

    2014-01-01

    Rolling pistons are widely used as compressors in air conditioning systems due to their small size, low cost, and high performance. Reed valves, a special type of check valve driven by hydraulic forces, are commonly used with many types of compressors to restrict the flow to one direction. Reed valves are typically made of a thin layer of metal or plastic materials. The valve will bend in response to fluid pressure forces to open up the flow channel at the proper moment within the compression...

  11. Transaction management with integrity checking

    DEFF Research Database (Denmark)

    Martinenghi, Davide; Christiansen, Henning

    2005-01-01

    , which are difficult to maintain and error prone. Two important aspects must be taken care of. 1.~It is too time consuming to check integrity constraints from scratch after each update, so simplified checks before each update should be used relying on the assumption that the current state is consistent...

  12. Checks and Controls in Spreadsheets

    CERN Document Server

    O'Beirne, Patrick

    2009-01-01

    Spreadsheets that are informally created are harder to test than they should be. Simple cross-foot checks or being easily readable are modest but attainable goals for every spreadsheet developer. This paper lists some tips on building self-checking into a spreadsheet in order to provide more confidence to the reader that a spreadsheet is robust.

  13. Heimlich valve and pneumothorax.

    Science.gov (United States)

    Gogakos, Apostolos; Barbetakis, Nikolaos; Lazaridis, George; Papaiwannou, Antonis; Karavergou, Anastasia; Lampaki, Sofia; Baka, Sofia; Mpoukovinas, Ioannis; Karavasilis, Vasilis; Kioumis, Ioannis; Pitsiou, Georgia; Katsikogiannis, Nikolaos; Tsakiridis, Kosmas; Rapti, Aggeliki; Trakada, Georgia; Zissimopoulos, Athanasios; Tsirgogianni, Katerina; Zarogoulidis, Konstantinos; Zarogoulidis, Paul

    2015-03-01

    The Heimlich valve is a small one-way valve used for chest drainage that empties into a flexible collection device and prevents return of gases or fluids into the pleural space. The Heimlich valve is less than 13 cm (5 inches) long and facilitates patient ambulation. Currently there are several systems in the market. It can be used in many patients instead of a traditional water seal drainage system. The Heimlich chest drainage valve was developed so that the process of draining the pleural cavity could be accomplished in a safe, relatively simple, and efficient manner. This valve system has replaced the cumbersome underwater drainage bottle system. Moreover; the Heimlich valve system connects to chest tubing and allows fluid and air to pass in one direction only. This system functions in any position, and it does not ever need to be clamped, a regulated suction can be attached to it if necessary. The valve drains into a plastic bag that can be held at any level, allowing the patient undergoing chest drainage to be ambulatory simply by carrying the bag. In the current mini review we will present the Heimlich valve system and method of insertion. PMID:25861609

  14. Shutoff and throttling valve

    Science.gov (United States)

    Hays, L. G.

    1974-01-01

    Leaktight shutoff, precise flow control, and very low pressure drop are incorporated in all-metal valve designed for operation under extreme temperatures. Valve constructed with refractory metal is intended for control of high-temperature liquid cesium, but has applications related to control of high- and low-temperature liquids and gases.

  15. Issues behind Competitiveness and Carbon Leakage

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-07-01

    This report explores the vulnerability of heavy industry to carbon leakage and competitiveness loss. It reviews the existing literature on competitiveness and carbon leakage under uneven climate policies. It also suggests a statistical method to track carbon leakage, and applies this methodology to Phase I of the EU emissions trading scheme, for various industrial activities: iron and steel, cement, aluminium and refineries. Finally, it reviews measures to mitigate carbon leakage, as discussed in Australia, Canada, Europe, New Zealand and the US.

  16. Anticoagulation for Prosthetic Valves

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Kaneko

    2013-01-01

    Full Text Available Implantation of prosthetic valve requires consideration for anticoagulation. The current guideline recommends warfarin on all mechanical valves. Dabigatran is the new generation anticoagulation medication which is taken orally and does not require frequent monitoring. This drug is approved for treatment for atrial fibrillation and venous thromboembolism, but the latest large trial showed that this drug increases adverse events when used for mechanical valve anticoagulation. On-X valve is the new generation mechanical valve which is considered to require less anticoagulation due to its flow dynamics. The latest study showed that lower anticoagulation level lowers the incidence of bleeding, while the risk of thromboembolism and thrombosis remained the same. Anticoagulation poses dilemma in cases such as pregnancy and major bleeding event. During pregnancy, warfarin can be continued throughout pregnancy and switched to heparin derivative during 6–12 weeks and >36 weeks of gestation. Warfarin can be safely started after 1-2 weeks of discontinuation following major bleeding episode.

  17. Heat exchanger leakage problem location

    Directory of Open Access Journals (Sweden)

    Jícha Miroslav

    2012-04-01

    Full Text Available Recent compact heat exchangers are very often assembled from numerous parts joined together to separate heat transfer fluids and to form the required heat exchanger arrangement. Therefore, the leak tightness is very important property of the compact heat exchangers. Although, the compact heat exchangers have been produced for many years, there are still technological problems associated with manufacturing of the ideal connection between the individual parts, mainly encountered with special purpose heat exchangers, e.g. gas turbine recuperators. This paper describes a procedure used to identify the leakage location inside the prime surface gas turbine recuperator. For this purpose, an analytical model of the leaky gas turbine recuperator was created to assess its performance. The results obtained are compared with the experimental data which were acquired during the recuperator thermal performance analysis. The differences between these two data sets are used to indicate possible leakage areas.

  18. Heat exchanger leakage problem location

    Science.gov (United States)

    Hejčík, Jiří; Jícha, Miroslav

    2012-04-01

    Recent compact heat exchangers are very often assembled from numerous parts joined together to separate heat transfer fluids and to form the required heat exchanger arrangement. Therefore, the leak tightness is very important property of the compact heat exchangers. Although, the compact heat exchangers have been produced for many years, there are still technological problems associated with manufacturing of the ideal connection between the individual parts, mainly encountered with special purpose heat exchangers, e.g. gas turbine recuperators. This paper describes a procedure used to identify the leakage location inside the prime surface gas turbine recuperator. For this purpose, an analytical model of the leaky gas turbine recuperator was created to assess its performance. The results obtained are compared with the experimental data which were acquired during the recuperator thermal performance analysis. The differences between these two data sets are used to indicate possible leakage areas.

  19. Development of the live-loading valve design system

    International Nuclear Information System (INIS)

    Seal engineering was developed to improve the reliability and operability of power plants. A major problem is leakage from valve which occurs because of stress relaxation of the packing rings. Live-loading is an effective method which compensates for packing relaxation with a spring load. To apply the live-loading device to valves, the authors have investigated a packing mechanism with a spring load. In addition, they have developed a design system for the live-loading using a personal computer based on this investigation. Referring to this design system, they manufactured a prototype live-loading valve to evaluate the performance of the live-loading device through testing. The test data corresponded well with the data calculated by the live-loading design system. They have concluded that this design system could be applied to actual use

  20. [Preliminary study of a new heart valve prostheses implanted with minimally invasive techniques: pulsatile-flow testing in vitro].

    Science.gov (United States)

    Tang, Jinglong; Wang, Shuo; Liu, Li; Wang, Jian; Wang, Chunren

    2013-02-01

    The aim of this study was to investigate the pulsatile-flow performance in vitro of a new heart valve prostheses implanted with minimally invasive techniques (HVPMIT). Three HVPMITs were tested valves and another three original biological heart valve prostheses acted as reference valves. The pulsatile-flow parameters (including mean pressure drop, regurgitant percentage of stroke volume, and effective orifice area) were tested in a pulse duplicator according to the methods listed in ISO5840-2005 and GB 12279-2008. The results demonstrated that the regurgitant percentage of stroke volume of tested valves was up to 13%. It was significantly higher than that of the reference valves. This result suggested that paravalvular leakage had occurred in the tested valves. It was found in the further analysis that because HVPMIT was not sewn into the heart tissue when the HVPMIT was implanted in vivo and there was not a sewing ring in the HVPMIT, when tested valves were fixed in the pulse duplicator, some gaps might exist between the stent of HVPMIT and the fix gasket, and the paravalvular leakage could therefore take place through these gaps. This study demonstrated that there are significant differences in the shape, structure, fixation in vivo and clinical operational methods between HVPMIT and original biological heart valve prostheses. It is necessary to establish new test methods which adapt for HVPMIT to evaluate its pulsatile-flow performance according to its own features. PMID:23488159

  1. New methods of concurrent checking

    CERN Document Server

    Goessel, Michael; Sogomonyan, Egor; Marienfeld, Daniel

    2008-01-01

    Written by a team of two leading experts and two very successful young former PhD students, New Methods of Concurrent Checking describes new methods of concurrent checking, such as partial duplication, use of output dependencies, complementary circuits, self-dual parity, self-dual duplication and others. A special chapter demonstrates how the new general methods of concurrent checking can be more specifically applied to regular structures to obtain optimum results. This is exemplified for all types of adders up to 64 bits with a level of detail never before presented in the literature. The cle

  2. 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.

  3. Computational valve plate design

    Science.gov (United States)

    Kalbfleisch, Paul

    Axial piston machines are widely used in many industries for their designs compactness, flexibility in power transfer, variable flow rate, and high efficiencies as compared to their manufacturing costs. One important component of all axial piston machines that is a very influential on the performance of the unit is the valve plate. The aim of this research is to develop a design methodology that is general enough to design all types of valve plates and the simple enough not to require advanced technical knowledge from the user. A new style of valve plate designs has been developed that comprehensively considers all previous design techniques and does not require significant changes to the manufacturing processes of valve plates. The design methodology utilizes a previously developed accurate computer model of the physical phenomenon. This allows the precise optimization of the valve plate design through the use of simulations rather than expensive trial and error processes. The design of the valve plate is clarified into the form of an optimization problem. This formulation into an optimization problem has motivated the selection of an optimization algorithm that satisfies the requirements of the design. The proposed design methodology was successfully tested in a case study in the shown to be very successful in improving required performance of the valve plate design.

  4. Gate valve performance prediction

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2014-01-01

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

  6. Diseases of the Tricuspid Valve

    Science.gov (United States)

    ... Myocarditis Obstructive Sleep Apnea Pericarditis Peripheral Vascular Disease Rheumatic Fever Sick Sinus Syndrome Silent Ischemia Stroke Sudden Cardiac Arrest Valve Disease Vulnerable Plaque Diseases of the Tricuspid Valve | Share Diseases of the heart valves are grouped according to which valve or ...

  7. Body checking behaviors in men.

    Science.gov (United States)

    Walker, D Catherine; Anderson, Drew A; Hildebrandt, Thomas

    2009-06-01

    Males have been facing increasing pressure from the media to attain a lean, muscular physique, and are at risk for body dissatisfaction, disturbed eating and exercise behaviors, and abuse of appearance- and performance-enhancing drugs (APEDs). The aim of the current study was to examine the relationship between body checking and mood, symptoms of muscle dysmorphia, importance of shape and weight, and APED use in undergraduate males. Body checking in males was correlated with weight and shape concern, symptoms of muscle dysmorphia, depression, negative affect, and APED use. Body checking predicted APED use and uniquely accounted for the largest amount of variance in Muscle Dysmorphic Disorder Inventory (MDDI) scores (16%). Findings support the view that body checking is an important construct in male body image, muscle dysmorphia, and body change strategies and suggest a need for further research. PMID:19482568

  8. Model Checking Algorithms for CTMDPs

    DEFF Research Database (Denmark)

    Buchholz, Peter; Hahn, Ernst Moritz; Hermanns, Holger;

    2011-01-01

    Continuous Stochastic Logic (CSL) can be interpreted over continuoustime Markov decision processes (CTMDPs) to specify quantitative properties of stochastic systems that allow some external control. Model checking CSL formulae over CTMDPs requires then the computation of optimal control strategie...

  9. Treasury Check Verification Query (TCVQ)

    Data.gov (United States)

    Social Security Administration — The TCVQ system determines the SSN of an individual whose check has been returned to a local field office. The FO is able to request this information via the TCVQ...

  10. Danfos: Thermostatic Radiator Valves

    DEFF Research Database (Denmark)

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

    2000-01-01

    This problem deals with modelling the flow through a typical Danfoss thermostatic radiator valve.Danfoss is able to employ Computational Fluid Dynamics (CFD) in calculations of the capacity of valves, but an experienced engineer can often by rules of thumb "guess" the capacity, with a precision...... similar to the one achieved by the expensive and time-consuming CFD calculations. So CFD is only used in case of entirely new designs or where a very detailed knowledge of the flow is required. Even though rules of thumb are useful for those, who have developed them, Danfoss needs an objective and general...... method that can be used to predict the performance of valves....

  11. GIANT PROSTHETIC VALVE THROMBUS

    Directory of Open Access Journals (Sweden)

    Prashanth Kumar

    2015-04-01

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

  12. Body checking behaviors in men

    OpenAIRE

    Walker, D. Catherine; Anderson, Drew A.; Hildebrandt, Thomas

    2009-01-01

    Males have been facing increasing pressure from the media to attain a lean, muscular physique, and are at risk for body dissatisfaction, disturbed eating and exercise behaviors, and abuse of appearance- and performance-enhancing drugs (APEDs). The aim of the current study was to examine the relationship between body checking and mood, symptoms of muscle dysmorphia, importance of shape and weight, and APED use in undergraduate males. Body checking in males was correlated with weight and shape ...

  13. Model checking PSL safety properties

    OpenAIRE

    Launiainen, Tuomas

    2009-01-01

    Model checking is a modern, efficient approach to gaining confidence of the correctness of complex systems. It outperforms conventional testing methods especially in cases where a high degree of confidence in the correctness of the system is required, or when the test runs of the system are difficult to reproduce accurately. In model checking the system is verified against a specification that is expressed in a formal specification language. The main challenges are that the process requires q...

  14. Model composition in model checking

    OpenAIRE

    Felscher, Ingo

    2014-01-01

    Model-checking allows one to formally check properties of systems: these properties are modeled as logic formulas and the systems as structures like transition systems. These transition systems are often composed, i.e., they arise in form of products or sums. The composition technique allows us to deduce the truth of a formula in the composed system from "interface information": the truth of formulas for the component systems and information in which components which of these formulas hold. W...

  15. INFLUENCE OF MIMIC CARDIAC RATE ON HYDRODYNAMICS OF DIFFERENT MECHANICAL PROSTHETIC CARDIAC VALVES IN VITRO

    Institute of Scientific and Technical Information of China (English)

    Yin-ping Chu; Jin-lian Cheng; Ru-kun Chen; Yu-bo Fan; Fang Pu

    2005-01-01

    Objective To assess the influence of mimic cardiac rate on hydrodynamics of different mechanical prosthetic cardiac valves.Methods US-made CarboMedics bileaflet valve, China-made Jiuling bileaflet valve and C-L tilting disc valve were tested via a pulsatile flow simulator in the aortic position. Testing conditions were set at mimic cardiac rates of 55 bpm, 75 bpm, 100bpm with a constant mimic cardiac output of 4 L/min. The mean pressure differences (△P), leakage volumes (LEV) and closing volumes (CLV) across each valve, and effective orifice areas (EOA) were analyzed.Results Within physiological range, △p, LEV, and CLV decreased as mimic cardiac rate increased, with a large extent of variance. EOA increased along with an increase in mimic cardiac rate. It was a different response in terms of cardiac rate alteration for different types of mechanical prosthetic cardiac valves.Conclusion Mimic cardiac rate change affects hydrodynamics of mechanical prosthetic cardiac valves. Within physiological range, the hydrodynamic of prosthetic bileaflet valve is better than that of tilting disc valve.

  16. Calculating the GONG Leakage Matrix

    Science.gov (United States)

    Hill, F.; Howe, R.

    Since spherical harmonics do not form a complete orthonormal basis set over a portion of a sphere, helioseismic spectra computed for a specific target mode with degree ellt and azimuthal degree mt also contain modes with nearby ell'' and m''. These spatial leaks greatly increase the complexity of the observed spectrum, complicating the spectral fitting and degrading the resulting mode parameter estimates. This is particularly true where the target mode and the leaks have similar frequencies. Some strategies for fitting helioseismic spectra explicitly include the leakage matrix which estimates the relative strength of a mode (ell'' and m'') in the spectrum at (ellt,mt). Since the fitting methods assume that the matrix is correct and apply it as a constraint, an inaccurate matrix introduces systematic errors in the estimated mode parameters. It is thus important to have as accurate a matrix as possible. Here we report on the calculation of the leakage matrix for the GONG observations. The matrix elements are essentially the integrals (over the observed portion of the solar surface) of the crossproducts of the two spherical harmonics. However, several effects have been included to increase the accuracy of the matrix. These include the projection factor of the observable (velocity, intensity, modulation), the spatial apodization applied to the data, the finite rectangular pixel dimensions of the observations, and possible errors in the estimated image geometry. Other factors to be incorporated are the observed MTF, the merging of the GONG images, and the horizontal components of the oscillatory velocity field. We will compare the latest calculation with the observed spectrum and assess the relative importance of the input factors. We will also compare the leakage matrices for velocity and intensity to estimate their contribution to the large apparent differences in the helioseismic spectra obtained from these observables.

  17. Mitral valve regurgitation

    Science.gov (United States)

    ... MVP) Rare conditions, such as untreated syphilis or Marfan syndrome Rheumatic heart disease. This is a complication ... the arteries Heart failure - overview High blood pressure Marfan syndrome Mitral valve prolapse Pulmonary embolus Stroke Update ...

  18. Aortic valve replacement

    DEFF Research Database (Denmark)

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

    2008-01-01

    BACKGROUND AND AIMS OF THE STUDY: Prompted by anecdotal evidence and observations by surgeons, an investigation was undertaken into the potential differences in implanted aortic valve prosthesis sizes, during aortic valve replacement (AVR) procedures, between northern and southern European...... countries. METHODS: A multi-institutional, non-randomized, retrospective analysis was conducted among 2,932 patients who underwent AVR surgery at seven tertiary cardiac surgery centers throughout Europe. Demographic and perioperative variables including valve size and type, body surface area (BSA) and early......: Prostheses with diameter valve size was also smaller in southern compared to northern European patients (21.6 +/- 2.1 mm versus 23.4 +/- 2.2 mm, p

  19. Automatization and familiarity in repeated checking

    NARCIS (Netherlands)

    Dek, Eliane C P; van den Hout, Marcel A.; Giele, Catharina L.; Engelhard, Iris M.

    2014-01-01

    Repeated checking paradoxically increases memory uncertainty. This study investigated the underlying mechanism of this effect. We hypothesized that as a result of repeated checking, familiarity with stimuli increases, and automatization of the checking procedure occurs, which should result in decrea

  20. Topological qubit design and leakage

    Energy Technology Data Exchange (ETDEWEB)

    Ainsworth, R; Slingerland, J K, E-mail: robert.ainsworth@nuim.ie, E-mail: joost@thphys.nuim.ie [Department of Mathematical Physics, National University of Ireland Maynooth, Co. Kildare (Ireland)

    2011-06-15

    We examine how best to design qubits for use in topological quantum computation. These qubits are topological Hilbert spaces associated with small groups of anyons. Operations are performed on these by exchanging the anyons. One might argue that in order to have as many simple single-qubit operations as possible, the number of anyons per group should be maximized. However, we show that there is a maximal number of particles per qubit, namely 4, and more generally a maximal number of particles for qudits of dimension d. We also look at the possibility of having topological qubits for which one can perform two-qubit gates without leakage into non-computational states. It turns out that the requirement that all two-qubit gates are leakage free is very restrictive and this property can only be realized for two-qubit systems related to Ising-like anyon models, which do not allow for universal quantum computation by braiding. Our results follow directly from the representation theory of braid groups, which implies that they are valid for all anyon models. We also make some remarks about generalizations to other exchange groups.

  1. Atrioventricular valve replacement in functional single-ventricle patients

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhong; CEN Jian-zheng; XU Gang; WEN Shu-sheng; CHEN Ji-mei

    2016-01-01

    Background This article summarized the experience of atrioventricular valve replacement operation for functional single ventricle patients whose atrioventricular valve was insufficiency.The follow-up time of operation was arranged from early-to medium-term.Methods From July 2009 to July 2015,there were 40 patients of functional single ventricle receiving the operation of atrioventricular valve replacement,including 23 male and 17 female patients.The age at A-Ⅴ valve replacement was ranged from 6 days to 32 years (the medium age of 9 years),and the body weight ranged from 2.7 to 57 kg (the medium body weight of 21.5 kg).Moreover,the atrioventricular valve replacement was performed on all patients under extracorporeal circulation.Results Atrioventricular valve replacement was performed on 40 patients with function single ventricle in hospital,of which eight (20.0%) died in hospital including two neonate and infant (age range:6 days-2 years old) accounting for 25% (2/8),Among them,seven patients died of low cardiac output syndrome two patients with repeated hypoxemia concurrent infection after operation,and one with bilateral diaphragmatic paralysis and malignant arrhythmia.For the patients suffering the severe perivalvular leakage,there was a reoperation,and the cardiac function before the first operation was class Ⅳ.One patient received heart transplantation finally for severe heart failure after AV valve replacement.For the rest of patients,their cardiac function recovered to class Ⅰ-Ⅱ after operation.Conclusions For function single ventricle patients with atrioventricular valve regurgitation,the mortality rate of atrioventricular valve replacement can be accepted if the operation was indicated.For patients with severe atrioventricular value regurgitation,the result of the operation in the early and medium term was satisfying.Thus,the atrioventricular valve replacement served as a useful treatment for patients diagnosed of A-Ⅴ valve regurgitation and

  2. Motor operated valve signatures events extraction module using an specialist system for the nuclear power plant MOV diagnostic system

    International Nuclear Information System (INIS)

    A predictive maintenance program for motor-operated valves is performed every year at Angra I Nuclear Power Plant in order to detect early failures of the valves and to diagnosis the valve degradation. The purpose of this maintenance program is to increase the reactor reliability and security. The main predictive maintenance activities are usually performed in the swing check-valves, gate valves and globe valves. The valves data analysis usually performed during the plant outage allows one to detect any failure and adjust the valves parameters like torque-switch and limitorque. The main purpose of this thesis is to develop a computer program to select the valve events parameter using the valve power signature during the closed-open and open-closed cycles. The results obtained by the developed algorithm are connected to a developed specialist system to perform the valves events identification. An important contribution of this thesis is that the valves signature features are obtained without changing the signal morphology. (author)

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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

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

    2012-09-01

    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.

  5. Design and theoretical analysis of a sliding valve distribution radial piston pump

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Guo; Shengdun, Zhao; Yanghuiwen, Yu [Xian Jiaotong University, Xian (China); Peng, Shang [Xian Engineering University of Armed Police Force, Xian (China)

    2016-01-15

    A Sliding valve distribution radial piston pump (SVDRPP) is presented. In this pump, a new distribution method that uses sliding valves to distribute oil for the piston chambers is developed. With this design, the disadvantages brought by the distribution shaft and the check valves (traditional distribution mechanisms), such as the poor stress state of the shaft and the energy waste for opening the check valves, are expected to be eliminated. In addition, a method of using pressure oil to accomplish the returning stroke of the piston is also proposed, which could be used to replace the usage of springs along with their shortcomings. A pump with five pistons is designed as an example to elaborate the structure and the working principle of SVDRPP. Furthermore, the flow characteristics of SVDRPP are studied, and the formulas of the displacement, the average flow rate and the instantaneous flow rate are deduced.

  6. Model Checking Linearizability via Refinement

    Science.gov (United States)

    Liu, Yang; Chen, Wei; Liu, Yanhong A.; Sun, Jun

    Linearizability is an important correctness criterion for implementations of concurrent objects. Automatic checking of linearizability is challenging because it requires checking that 1) all executions of concurrent operations be serializable, and 2) the serialized executions be correct with respect to the sequential semantics. This paper describes a new method to automatically check linearizability based on refinement relations from abstract specifications to concrete implementations. Our method avoids the often difficult task of determining linearization points in implementations, but can also take advantage of linearization points if they are given. The method exploits model checking of finite state systems specified as concurrent processes with shared variables. Partial order reduction is used to effectively reduce the search space. The approach is built into a toolset that supports a rich set of concurrent operators. The tool has been used to automatically check a variety of implementations of concurrent objects, including the first algorithms for the mailbox problem and scalable NonZero indicators. Our system was able to find all known and injected bugs in these implementations.

  7. Air leakage in refrigerated vans. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1978-12-01

    The Air Leakage in Refrigerated Vans Project was initiated by the Department of Energy to assess the impact of air leakage on fuel consumption of highway transport refrigeration equipment. The project, conducted from September of 1977 to December of 1978 collected air leakage data on refrigerated trailers, containers and truck bodies. A Prototype Air Leakage Test Set was developed, designed and constructed to take measurements, and a total of 92 representative vehicles were examined. The results of the study indicate that air leakage causes a 25% increase in the average refrigeration load. However, the majority of transport refrigeration units are equipped with control systems that require the power to be supplied continuously, so that the potential reduction in fuel consumption that can be expected by reduced air leakage is limited. Alternative control techniques and power sources for the control and operation of refrigeration unit components other than the compressor could reduce fuel consumption by approximately 60%.

  8. LEAKAGE OF COLONIC ANASTOMOSIS AFTER COLON RESECTION

    Institute of Scientific and Technical Information of China (English)

    Kanellos I; Pramateftakis MG

    2004-01-01

    Objective To present the diagnosis and management of anastomotic leakage after colon resection. Methods Early diagnosis and urgent therapeutic intervention are required in order to avert life-threatening conditions that may be caused by anastomotic leakage. Results The diagnosis of anastomotic leakage is based on clinical features, peripheral blood investigations and abdominal computed tomography (CT) scan. Major leaks are defined by symptoms of peritonitis and septicaemia due to leakage. Major leaks should be managed operatively. Minor leaks can be managed conservatively with successful outcomes. Conclusion Leakage of colonic anastomosis remains the most serious complication after colon resection. It is a major cause of postoperative morbidity and mortality. A high index of suspicion is required in order to detect early, nonspecific signs of a leakage and urgent surgical intervention is usually required to avert life-threatening events.

  9. Leakage Power Reduction Using Bitwidth Optimization

    OpenAIRE

    Yasuura, Hiroto

    2002-01-01

    Leakage power dissipation constitutes an increasing fraction of the total power in modern semiconductor technologies. Designing power efficient products will require consideration of leakage power in the earliest phases of design. This paper addresses bitwidth optimization focusing on leakage power reduction for system-level low-power design. By means of tuning the design parameter, bitwidth tailored to a given application requirements, the datapath width of processors and size of memories ar...

  10. Leakage, entrepreneurship, and satisfaction in hospitality

    OpenAIRE

    GALDÓN SALVADOR, JOSÉ LUIS; Garrigós Simón, Fernando José; Gil Pechuán, Ignacio

    2013-01-01

    This is an Accepted Manuscript of an article published by Taylor & Francis in The Service Industries Journal on 2013, available online:http://www.tandfonline.com/10.1080/02642069.2013.740464 Tourism is a very important tool for economic development. However, its economic effects are mainly conditioned by the level of leakage. This work defines leakage, provides an original evaluation of the entrepreneurial environment in showing that it is the one with the lowest level of leakage, and crea...

  11. Acute myocardial ischemia after aortic valve replacement: A comprehensive diagnostic evaluation using dynamic multislice spiral computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lembcke, Alexander [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany)]. E-mail: alexander.lembcke@gmx.de; Hein, Patrick A. [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany); Enzweiler, Christian N.H. [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany); Hoffmann, Udo [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Klessen, Christian [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany); Dohmen, Pascal M. [Department of Cardiovascular Surgery, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany)

    2006-03-15

    We describe the case of a 72-year-old man presenting with endocarditis and clinical signs of acute myocardial ischemia after biological aortic valve replacement. A comprehensive cardiac dynamic multislice spiral computed tomography demonstrated: (1) an endocarditic vegetation of the aortic valve; (2) a subvalvular leakage feeding a paravalvular pseudoaneurysm based on an aortic root abscess with subsequent compromise of the systolic blood flow in the left main coronary artery and the resulting myocardial perfusion deficit.

  12. Practical Leakage-Resilient Symmetric Cryptography

    DEFF Research Database (Denmark)

    Faust, Sebastian; Pietrzak, Krzysztof; Schipper, Joachim

    2012-01-01

    -adaptively. For example, we show that a three round Feistel network instantiated with a leakage resilient PRF yields a leakage resilient PRP if the inputs are chosen non-adaptively (This complements the result of Dodis and Pietrzak [CRYPTO’10] who show that if a adaptive queries are allowed, a superlogarithmic number...... of rounds is necessary.) We also show that a minor variation of the classical GGM construction gives a leakage resilient PRF if both, the leakage-function and the inputs, are chosen non-adaptively...

  13. Estimation of leakage frequencies from different systems at Nordic nuclear power plants

    International Nuclear Information System (INIS)

    Within the project External Events (1994-97) it was decided to initialise the work on a handbook-, called X-Book, in order to provide the PSA analyst guidance in the selection of models and frequencies of 'external events'. Thus, the aim of the X-Book is to be complementary to the I-Book, a handbook on Initiating Events at Nordic nuclear power plants. The X-Book will, among other things, encompass the frequencies of so called system external events, i.e. initiating events that are caused by events occurring outside the system boundaries. In Version 1 of the X-Book the attention is mainly focussed on the estimation of initiating fire frequencies, per plant and per building. This frequency estimation was mainly based on data, specifically collected about fires occurred at Nordic power plants. Within the project mentioned above efforts were also started with the aim to estimate the frequencies of water/steam leakage, frequencies that can be used in PSA of risks related to flooding and steam rupture. The models and frequencies of events resulting in loss of cooling water (LOCA) that were used already in WASH-1400 have 'survived' in many later studies. According to the aim and ambitions of modern PSAs the need for improved treatment of water/steam leakages is more and more emphasised, both with respect to the modelling of the course of events and the estimation of frequencies of such events. Leakage from water-bearing systems may occur more or less spontaneously through cracks, pipe ruptures, damaged packing-boxes of pumps and valves etc. Thus this type of leakage may derive from pipe failures or leaking active or passive components. External leakage may also occur if a valve is spuriously opened between low and high pressure systems or towards a temporarily opened part of a system (Interfacing V-LOCA). This report describes the methods used in the selection of leakage data from the Nordic NPP component data base TUD as well as the models and methods applied in the

  14. [Technologies for cardiac valve prostheses].

    Science.gov (United States)

    Nakano, Kiyoharu

    2009-07-01

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

  15. Emission-free valve

    Energy Technology Data Exchange (ETDEWEB)

    Koppe, W.; Prummer, R.

    1980-07-01

    a description is given of an emission-free valve, particularly a magnetically operated valve, for use in controlling the flow of fluids, especially poisonous, radioactive, aggressive and otherwise dangerous gases and fluids, comprising a housing including a housing member which has substantially spherical configuration and an internal surface surrounding a compartment for the respective fluid, said housing further including an annular valve seat member; a valve member movably mounted in said compartment and cooperating with said valve seat member to control the flow of the fluid through said compartment; and a plating layer of a corrosion-resistant material covering said internal surface of said housing member and also having a substantially spherical configuration corresponding to that of said housing member, said housing member and said plating layer obtaining their respective configurations during an explosion which not only simultaneously deforms initially cylindrical tubular and coaxially arranged housing member and plating layer preforms, but also welds said plating layer preform to said housing member preform so that said platinglayer is explosion-welded to said housing member.

  16. Transcatheter Aortic Valve Replacement for Degenerative Bioprosthetic Surgical Valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John; Brecker, Stephen;

    2012-01-01

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

  17. Direct Model Checking Matrix Algorithm

    Institute of Scientific and Technical Information of China (English)

    Zhi-Hong Tao; Hans Kleine Büning; Li-Fu Wang

    2006-01-01

    During the last decade, Model Checking has proven its efficacy and power in circuit design, network protocol analysis and bug hunting. Recent research on automatic verification has shown that no single model-checking technique has the edge over all others in all application areas. So, it is very difficult to determine which technique is the most suitable for a given model. It is thus sensible to apply different techniques to the same model. However, this is a very tedious and time-consuming task, for each algorithm uses its own description language. Applying Model Checking in software design and verification has been proved very difficult. Software architectures (SA) are engineering artifacts that provide high-level and abstract descriptions of complex software systems. In this paper a Direct Model Checking (DMC) method based on Kripke Structure and Matrix Algorithm is provided. Combined and integrated with domain specific software architecture description languages (ADLs), DMC can be used for computing consistency and other critical properties.

  18. Compositional and Quantitative Model Checking

    DEFF Research Database (Denmark)

    Larsen, Kim Guldstrand

    2010-01-01

    on the existence of a quotient construction, allowing a property phi of a parallel system phi/A to be transformed into a sufficient and necessary quotient-property yolA to be satisfied by the component 13. Given a model checking problem involving a network Pi I and a property yo, the method gradually move (by...

  19. Research on Valve Body Design of Large Bore Sodium Valve

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Large bore sodium valve is one kind of key equipments of China Demonstration Fast Reactor (CDFR). It is installed in the pipeline before and behind SG units as a locking mechanism. Valve body which is used to bear pressure is the core of sodium valve design.

  20. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... a significant number of mitral valve repairs utilizing robotic techniques as well, which is really outside the ... no significant bleeding. Terry asks if you do robotic valve replacement surgeries. I do not. It's a ...

  1. Transcatheter Aortic Heart Valve Thrombosis

    DEFF Research Database (Denmark)

    Hansson, Nicolaj C; Grove, Erik L; Andersen, Henning R;

    2016-01-01

    BACKGROUND: There is increasing focus on transcatheter heart valve (THV) thrombosis. However, there are limited data on incidence, clinical implications and predisposing factors of THV thrombosis following transcatheter aortic valve replacement (TAVR). OBJECTIVES: We assessed the incidence...

  2. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... which is made out of pyrolitic carbon, basically metal and plastic. Again, blood flows through this valve. ... has a prosthetic valve should let all their treating physicians, dentists, et cetera, know that so that ...

  3. What Is Heart Valve Disease?

    Science.gov (United States)

    ... heart work harder and affect its ability to pump blood. Overview How the Heart Valves Work At the ... into the atria. As the ventricles contract, they pump blood through the pulmonary and aortic valves. The pulmonary ...

  4. Safety valve for offshore borehole

    Energy Technology Data Exchange (ETDEWEB)

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

    1977-10-06

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

  5. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... of that slide, that demonstrates that patients with New York Heart Association class heart failure 1 and ... right down the aortic valve and that's the new aortic valve that Dr. Streitman's placed. And you ...

  6. Josephson magnetic rotary valve

    Energy Technology Data Exchange (ETDEWEB)

    Soloviev, I. I. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation); Lukin Scientific Research Institute of Physical Problems, Zelenograd, Moscow (Russian Federation); Klenov, N. V. [Physics Department, Moscow State University, Moscow (Russian Federation); Lukin Scientific Research Institute of Physical Problems, Zelenograd, Moscow (Russian Federation); Bakurskiy, S. V. [Physics Department, Moscow State University, Moscow (Russian Federation); Moscow Institute of Physics and Technology, State University, Dolgoprudniy, Moscow region (Russian Federation); Faculty of Science and Technology and MESA+, Institute for Nanotechnology, University of Twente, Enschede (Netherlands); Bol' ginov, V. V.; Ryazanov, V. V. [Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka (Russian Federation); National University of Science and Technology MISiS, Moscow (Russian Federation); Kupriyanov, M. Yu. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation); Moscow Institute of Physics and Technology, State University, Dolgoprudniy, Moscow region (Russian Federation); Golubov, A. A. [Moscow Institute of Physics and Technology, State University, Dolgoprudniy, Moscow region (Russian Federation); Faculty of Science and Technology and MESA+, Institute for Nanotechnology, University of Twente, Enschede (Netherlands)

    2014-12-15

    We propose a control element for a Josephson spin valve. It is a complex Josephson device containing ferromagnetic (F) layer in the weak-link area consisting of two regions, representing 0 and π Josephson junctions, respectively. The valve's state is defined by mutual orientations of the F-layer magnetization vector and boundary line between 0 and π sections of the device. We consider possible implementation of the control element by introduction of a thin normal metal layer in a part of the device area. By means of theoretical simulations, we study properties of the valve's structure as well as its operation, revealing such advantages as simplicity of control, high characteristic frequency, and good legibility of the basic states.

  7. Josephson magnetic rotary valve

    International Nuclear Information System (INIS)

    We propose a control element for a Josephson spin valve. It is a complex Josephson device containing ferromagnetic (F) layer in the weak-link area consisting of two regions, representing 0 and π Josephson junctions, respectively. The valve's state is defined by mutual orientations of the F-layer magnetization vector and boundary line between 0 and π sections of the device. We consider possible implementation of the control element by introduction of a thin normal metal layer in a part of the device area. By means of theoretical simulations, we study properties of the valve's structure as well as its operation, revealing such advantages as simplicity of control, high characteristic frequency, and good legibility of the basic states

  8. Quantifying Information Leakage of Randomized Protocols

    DEFF Research Database (Denmark)

    Biondi, Fabrizio; Wasowski, Andrzej; Legay, Axel;

    2013-01-01

    The quantification of information leakage provides a quantitative evaluation of the security of a system. We propose the usage of Markovian processes to model and analyze the information leakage of deterministic and probabilistic systems. We show that this method generalizes the lattice of inform...

  9. Predicting Envelope Leakage in Attached Dwellings

    Energy Technology Data Exchange (ETDEWEB)

    Faakye, O. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States); Arena, L. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States); Griffiths, D. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States)

    2013-07-01

    The most common method for measuring air leakage is to use a single blower door to pressurize and/or depressurize the test unit. In detached housing, the test unit is the entire home and the single blower door measures air leakage to the outside. In attached housing, this 'single unit', 'total', or 'solo' test method measures both the air leakage between adjacent units through common surfaces as well air leakage to the outside. Measuring and minimizing this total leakage is recommended to avoid indoor air quality issues between units, reduce energy losses to the outside, reduce pressure differentials between units, and control stack effect. However, two significant limitations of the total leakage measurement in attached housing are: for retrofit work, if total leakage is assumed to be all to the outside, the energy benefits of air sealing can be significantly over predicted; for new construction, the total leakage values may result in failing to meet an energy-based house tightness program criterion. The scope of this research is to investigate an approach for developing a viable simplified algorithm that can be used by contractors to assess energy efficiency program qualification and/or compliance based upon solo test results.

  10. Leakage-resilient cryptography from minimal assumptions

    DEFF Research Database (Denmark)

    Hazay, Carmit; López-Alt, Adriana; Wee, Hoeteck;

    2013-01-01

    We present new constructions of leakage-resilient cryptosystems, which remain provably secure even if the attacker learns some arbitrary partial information about their internal secret key. For any polynomial ℓ, we can instantiate these schemes so as to tolerate up to ℓ bits of leakage. While the...

  11. The new-generation of solenoid injectors equipped with pressure-balanced pilot valves for energy saving and dynamic response improvement

    International Nuclear Information System (INIS)

    Highlights: • Distinct pilot-valve setups, typical of modern Common Rail injectors, are compared. • The analysis focuses on injector static leakages and the injector dynamic response. • Experimental results are integrated or explained by means of simulation data. - Abstract: A numerical–experimental analysis on a new generation of hydraulically controlled servo solenoid injectors for Euro 6 Diesel engine applications has been carried out. The main innovation of these high-pressure injectors is the replacement of the standard pilot-valve configuration with a pressure-balanced layout. The new setup is aimed at reducing clearance leakages and at improving the dynamic response of the needle to the electrical command. A previously developed advanced one-dimensional code for the simulation of Common Rail injection systems has been adapted to simulate the innovative injectors. In particular, electromagnetic, hydraulic and mechanical submodels have been set up for the pressure-balanced pilot-valve simulation. The validated numerical model of the injector has been applied to investigate the mechanics of the pressure-balanced pilot-valve and the sensitivity of the dynamic response of the needle to some of the innovative pilot-valve layout design parameters. Furthermore, the developed simulation tool has been used to examine the real impact that the replacement of the standard pilot-valve layout with a pressure-balanced one could have on the injected flow-rate performance. The comparative investigation between the standard and the innovative pilot-valve has been completed with an analysis of their experimental static leakages. A comparison has also been made with static leakages measured for hydraulically-controlled servo piezoelectric injectors. Finally, a simple and accurate thermodynamic flow model has been developed to predict static leakages in indirect-acting solenoid and piezoelectric injectors. This model has pointed out the significant dependence of static

  12. St Jude Medical Portico valve.

    Science.gov (United States)

    Manoharan, Ganesh; Spence, Mark S; Rodés-Cabau, Joseph; Webb, John G

    2012-09-01

    Transcatheter aortic valve implantation is increasingly being used to treat high-risk patients with symptomatic aortic valve disease. However, challenges still remain with current devices, both in terms of the procedure and the outcome. The St Jude Medical Portico transcatheter valve system is designed to mitigate some of these difficulties. We describe the device characteristics and how the device may impact on a TAVI procedure. An overview of the clinical experiences with the Portico valve system is also described. PMID:22995122

  13. Building valve amplifiers

    CERN Document Server

    Jones, Morgan

    2013-01-01

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

  14. SAFETY SHUTOFF VALVE

    DEFF Research Database (Denmark)

    2010-01-01

    It is disclosed a shut-off valve which acts automatically and has a fully mechanical performance with respect to the loosing of the tower-shape part balance under the effect of the special acceleration Which is arisen from the quakes waves or serious vibrations, while such vibrations are mainly...... resulted from collision or effusion. A static tower has been applied for the main core of this part of the valve which loses balance state under the effect of collision and bounces to the neighboring part, which results in release of the catch and blockage of the gas passing channel....

  15. Experimental evaluation of clinical colon anastomotic leakage

    DEFF Research Database (Denmark)

    Pommergaard, Hans-Christian

    2014-01-01

    , ischemia and insufficient surgical technique have been suggested to play a central role. Animal models are valuable means to evaluate pathophysiological mechanisms and may be used to test preventive measures aiming at reducing the risk of anastomotic leakage, such as external anastomotic coating. The aim...... of this thesis was to: Clarify the best suited animal to model clinical anastomotic leakage in humans; Create animal models mimicking anastomotic leakage in humans induced by insufficient surgical technique and tissue ischemia; Determine the best suited coating materials to prevent anastomotic leakage. STUDY 1...... of experimental animals were identified. The results indicated that the mouse and the pig are the best suited animals to evaluate clinical anastomotic leakage. However, the pig model is less validated and more costly to use compared with the mouse. Most frequently, rats are used as models. However, extreme...

  16. Cavitation problems in sodium valves

    International Nuclear Information System (INIS)

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

  17. Design and development of a helium injection system to improve external leakage detection during liquid nitrogen immersion tests

    OpenAIRE

    Townsend, Andrew; Mishra, Rakesh

    2016-01-01

    The testing of assemblies for use in cryogenic systems commonly includes evaluation at or near operating (therefore cryogenic) temperature. Typical assemblies include valves and pumps for use in liquid oxygen-liquid hydrogen rocket engines. One frequently specified method of cryogenic external leakage testing requires the assembly, pressurized with gaseous helium (GHe), be immersed in a bath of liquid nitrogen (LN2) and allowed to thermally stabilize. Component interfaces are then visually in...

  18. A Study on the Packing Friction Estimation of Power-Operated Valves in Nuclear Power Plants

    International Nuclear Information System (INIS)

    The purpose of this study is to estimate the packing friction of power-operated valve in nuclear power plants. The roll of packing in valve is preventing leakage through stem. Packing friction is highly depend on gland nut tightness which means higher reliability in sealing is lower operability. For the estimation of friction, we used statistical analysis and experimental analysis. In experimental approach, we have performed packing fY test and applied it to valve field test. In statistical approach, we have used 10 years DB of safety-related valve in nuclear power plant and analyzed packing friction based on confidence interval of sample. The comparison of two results shows that statistical analysis for packing friction are more accurate than fY analysis even though both approach have error compared to measured value but we confirmed that statistical approach is proper way to estimate packing friction

  19. Investigation on correlation of aerosol leakage rate with gas leakage rate in capillary

    International Nuclear Information System (INIS)

    It is necessary to build up the correlation of the aerosol leakage rate with the gas leakage rate for evaluating aerosol leakage of nuclear facilities. The method of evaluating leakage rate of gas and sub-micron aerosol was summarized and also investigated by experiment. The effects of upstream aerosol number concentration, flow velocity and upstream pressure on aerosol leakage were analyzed based on the experimental results. The results show that the aerosol leakage rate is linearly related to the gas leakage rate in capillary when the gas leakage rate is higher than 10-4 Pa · m3 · S-1; the aerosol leakage rate falls sharply due to the diffusion deposition mainly for sub-micron aerosol when the gas le rate is lower than 10-4 Pa · m3 · S-1. The aerosol leakage rate is explored to be expressed as a function of the gas leakage rate and the orifice length under some certain assumptions for practical application. (authors)

  20. Formal Checking of Multiple Firewalls

    Directory of Open Access Journals (Sweden)

    Nihel Ben Youssef

    2012-05-01

    Full Text Available When enterprises deploy multiple firewalls, a packet may be examined by different sets of firewalls. It has been observed that the resulting complex firewall network is highly error prone and causes serious security holes. Hence, automated solutions are needed in order to check its correctness. In this paper, we propose a formal and automatic method for checking whether multiple firewalls react correctly with respect to a security policy given in a high level declarative language. When errors are detected, some useful feedback is returned in order to correct the firewall configurations. Furthermore, we propose a priority-based approach to ensure that no incoherencies exist within the security policy. We show that our method is both correct and complete. Finally, it has been implemented in a prototype of verifier based on a satisfiability solver modulo theories. Experiment conducted on relevant case studies demonstrates the efficiency of our approach.

  1. An electrochemical active valve

    NARCIS (Netherlands)

    Neagu, C.R.; Gardeniers, J.G.E.; Elwenspoek, M.; Kelly, J.J.

    1997-01-01

    A novel electrochemical microactuator was developed, which operates as an active valve. The microactuator consists of an electrochemical cell and a membrane that deflects because of the pressure of oxygen gas generated by electrolysis. Relatively large pressures (up to tens of bars) can be reached w

  2. Vent Relief Valve Test

    Science.gov (United States)

    2008-01-01

    Shown is the disassembly, examination, refurbishment and testing of the LH2 ( liquid hydrogen) and LOX (liquid oxygen) vent and relief valves for the S-IVB-211 engine stage in support of the Constellation/Ares project. This image is extracted from high definition video and is the highest resolution available.

  3. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, J.; Ansanelli, E.

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market.

  4. Climate Policy and Carbon Leakage

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-07-01

    This report explores the effects of the EU emissions trading scheme on the aluminium sector (i.e. competitiveness loss and carbon leakage). With its very high electricity intensity, primary aluminium stands out in the heavy industry picture: a sector whose emissions are not capped in the present EU ETS, European aluminium smelters still stand to lose profit margins and, possibly, market shares, as electricity prices increase following CO2 caps on generators' emissions - the famous pass-through of CO2 prices into electricity prices. The analysis includes a method of quantification of this issue, based on two indicators: profit margins and trade flows. As the EU is at the forefront of such policy, the paper provides policy messages to all countries on how trade exposed energy-intensive industries can be 'moved' by carbon constraint. This also is a contentious topic in Australia, Japan, New Zealand, and the US, where ambitious climate policies -- including cap-and-trade systems -- are currently debated.

  5. Leakage of caesium braquitherapy sources

    International Nuclear Information System (INIS)

    In several Venezuelan public hospitals where cervix uteri tumours are treated by intracavitary radiotherapy, that use manual after loading Fletcher method, with Caesium 137 sources, the use of improper source holders, locally manufactured from pieces of drainage plastic tubing, which deteriorated and created a corrosive environment all around the sources, omission of manufacturer's recommendations regarding corrosion information, source storage, inspection and testing, violation of International Atomic Energy Agency Radiation Protection Procedures, and lack of proper regulatory control, resulted integrity damage to about sixty special form sources (ISO2919 C 63322), leakage of Cs-137 from a supposed insoluble refractory active content (caesium silicoaluminate), and contamination of applicators, floors and bedding. When the situation was detected by means removal contamination tests, after routine inspections, the sources were removed from the hospitals, decontaminated by means of immersion in 3% EDTA solution in ultrasonic bath, subjected to leaking assessment tests, and the ones that passed were placed in low cost stainless steel source holders, designed and built by the instituto Venezolano de Investigaciones Cientificas (IVIC) returned to the hospitals. The leaking sources were removed from use and considered radioactive waste. In order to avoid the occurrence of similar situations, all the importers of such sources are now required to send them to IVIC for testing and placement in proper source holders, before they are shipped to the hospitals. (author)

  6. Checking modes of HAL programs

    OpenAIRE

    de la Banda, MG; Harvey, W; Marriott, K.; Stuckey, PJ; Demoen, Bart

    2005-01-01

    Recent constraint logic programming (CLP) languages, such as HAL and Mercury, require type, mode and determinism declarations for predicates. This information allows the generation of efficient target code and the detection of many errors at compile-time. Unfortunately, mode checking in such languages is difficult. One of the main reasons is that, for each predicate mode declaration, the compiler is required to appropriately re-order literals in the predicate's definition. The task is further...

  7. Liquid metal plasma valve development

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-06-01

    A program for the development of liquid-metal plasma valves (LMPVs) is discussed in detail. The program consisted of two tasks. The first was the development and testing of valves in the laboratory and the fabrication, instrumentation, testing and in-service operation of two valves at the Bonneville Power Adminstration (BPA) facilities of the Pacific Intertie HVDC Power Tansmission System at Celilo, Oregon. The second task was the design, development, fabrication, installation, and operation of a voltage and current monitoring station and the transient event recording system to go with it. Information is present on the design and development of converter valves; LMPV principles; and the testing of prototype valves. (LCL)

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

    Energy Technology Data Exchange (ETDEWEB)

    Souteyrand, Geraud, E-mail: gsouteyrand@chu-clermontferrand.fr [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France); Wilczek, Krzysztof [Department of Cardiology, Medical University of Silesia, Silesian Centre for Herat Diseases, Zabrze (Poland); Innorta, Andrea; Camilleri, Lionel [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France); Chodor, Piotr [Department of Cardiology, Medical University of Silesia, Silesian Centre for Herat Diseases, Zabrze (Poland); Lusson, Jean-René; Motreff, Pascal [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France); Laborde, Jean-Claude [St. George' s Hospital, London (United Kingdom); Chabrot, Pascal; Durel, Nicolas [Department of Cardiology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, Clermont-Ferrand (France); ERIM-EA3295, University of Auvergne, Clermont-Ferrand (France)

    2013-09-15

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

  9. Measurement of reed valve kinematics

    Science.gov (United States)

    Fenkl, Michael; Dvořák, Václav; Vít, Tomáš

    2016-03-01

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

  10. Measurement of reed valve kinematics

    Directory of Open Access Journals (Sweden)

    Fenkl Michael

    2016-01-01

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

  11. Packaged Au-PPy valves for drug delivery systems

    Science.gov (United States)

    Tsai, Han-Kuan A.; Ma, Kuo-Sheng; Zoval, Jim; Kulinsky, Lawrence; Madou, Marc

    2006-03-01

    The most common methods for the drug delivery are swallowing pills or receiving injections. However, formulations that control the rate and period of medicine (i.e., time-release medications) are still problematic. The proposed implantable devices which include batteries, sensors, telemetry, valves, and drug storage reservoirs provide an alternative method for the responsive drug delivery system [1]. Using this device, drug concentration can be precisely controlled which enhances drug efficiency and decreases the side effects. In order to achieve responsive drug delivery, a reliable release valve has to be developed. Biocompatibility, low energy consumption, and minimized leakage are the main requirements for such release method. A bilayer structure composed of Au/PPy film is fabricated as a flap to control the release valve. Optimized potentiostatic control to synthesize polypyrrole (PPy) is presented. The release of miniaturize valve is tested and showed in this paper. A novel idea to simultaneously fabricate the device reservoirs as well as protective packaging is proposed in this paper. The solution of PDMS permeability problem is also mentioned in this article.

  12. Calculation of Leakage Inductance for High Frequency Transformers

    DEFF Research Database (Denmark)

    Ouyang, Ziwei; Jun, Zhang; Hurley, William Gerard

    2015-01-01

    Frequency dependent leakage inductance is often observed. High frequency eddy current effects cause a reduction in leakage inductance. The proximity effect between adjacent layers is responsible for the reduction of leakage inductance. This paper gives a detailed analysis of high frequency leakage...... inductance and proposes an accurate prediction methodology. High frequency leakage inductances in several interleaved winding configurations are also discussed. Interleaved winding configurations actually give a smaller degree of reduction of leakage induction at high frequency. Finite Element Analysis (FEA...

  13. Developments in mechanical heart valve prosthesis

    Indian Academy of Sciences (India)

    Kalyani Nair; C V Muraleedharan; G S Bhuvaneshwar

    2003-06-01

    Artificial heart valves are engineered devices used for replacing diseased or damaged natural valves of the heart. Most commonly used for replacement are mechanical heart valves and biological valves. This paper briefly outlines the evolution, designs employed, materials being used,. and important factors that affect the performance of mechanical heart valves. The clinical performance of mechanical heart valves is also addressed. Efforts made in India in the development of mechanical heart valves are also discussed.

  14. In Vitro Study of Influence of Mimic Cardiac Rate on Hydrodynamics of the Different Mechanical Cardiac Valve Prostheses

    Institute of Scientific and Technical Information of China (English)

    CHU Yin-ping; CHENG Jin-lian; CHEN Ru-kun; FAN Yu-bo; PU Fang

    2005-01-01

    Objective:To assess the influence of mimic cardiac rate on hydrodynamics of the different mechanical prosthetic cardiac valves. Methods: US-made CarboMedics bileaflet valve and China-made Jiuling bileaflet valve and C-L tilting disc valve have been tested in a pulsatile flow simulator in the aortic position. The testing condition was set at the mimic cardiac rate of 55 beats/min,75 beats/min,100beats/min and a constant mimic cardiac output of 4L/min. The mean pressure differences (△P) ,leakage volumes (LEV) and closing volumes (CLV) across each valve,and the effective orifice areas(EOA) have been analyzed. Results:Within the range of physiology,the △P,LEV and CLV were falling as the increasing of mimic cardiac rate,and the extent of variance was larger. The EOA was increasing with the increase of the mimic cardiac rate. It is a different response as the altering of the cardiac rate for the different type of the mechanical prosthetic cardiac valves.Conclusions:The change of the mimic cardiac rate can affect the hydrodynamics of the mechanical prosthetic cardiac valves. The hydrodynamics of the bileaflet valve prosthesis is better than the tilting disc valve.

  15. Valve-in-valve transcatheter aortic valve implantation overcoming hostile anatomy: Evolut R for the treatment of Mitroflow bioprosthesis dysfunction.

    Science.gov (United States)

    Ruparelia, Neil; Colombo, Antonio; Latib, Azeem

    2016-10-01

    Redo surgery is regarded as the first-line treatment option for patients presenting with prosthetic valve degeneration. However, many patients have concomitant co-morbidities and this option is associated with significant risk. Transcatheter valve-in-valve implantation is an alternative strategy depending on the bioprosthetic valve that is being treated. The Sorin Mitroflow bioprosthetic aortic valve has been regarded as a contraindication to valve-in-valve treatment due to the high risk of coronary obstruction. We here present the case of a patient with small peripheral vasculature who underwent successful transfemoral valve-in-valve implantation and subsequently discuss the challenges and technical aspects that require consideration.

  16. Evaluation of an acoustic leak analyser for use on PWR valves in sub-cooled water

    International Nuclear Information System (INIS)

    This Report describes the work carried out to evaluate the performance of a commercial acoustic leak analyser for use on valves isolating pipework sections containing sub-cooled water. The investigation was carried out in 3 parts: (1) linking the analyser to a micro-computer to facilitate data storage, high resolution plotting and mathematical manipulation. (2) production of calibration curves of leakage noise versus known leak rate in cold water for different valve designs. (3) a review of the fundamental mechanisms causing noise in fluids and a comparison with the experimental data. (author)

  17. Architectural Leakage Power Minimization of Scratchpad memories

    Directory of Open Access Journals (Sweden)

    S. Paraneetharan,

    2012-03-01

    Full Text Available Partitioning a memory into multiple blocks that can be independently accessed is a widely used technique to reduce its dynamic power. For embedded systems, its benefits can be even pushed further by properly matching the partition to the memory access patterns. When leakage energy comes into play, however, idle memory blocks must be put into a proper low-leakage sleep state to actually save energy when not accessed. In this case, the matching becomes an instance of the power management problem, because moving to and from this sleep state requires additional energy. An effective solution to the problem of the leakage-aware partitioning of a memory into disjoint sub blocks, in particular, target scratchpad memories, which are commonly used in some embedded systems as a replacement for caches. By this approach, it is able to provide an optimal solution to the leakage-aware partitioning problem.

  18. Early Alzheimer's Linked to Brain 'Leakage'

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_159116.html Early Alzheimer's Linked to Brain 'Leakage' Normally, blood-brain barrier ... HealthDay News) -- People in the early stages of Alzheimer's disease may have more "leaks" in the barrier ...

  19. Analysis of ONKALO water leakage mapping results

    International Nuclear Information System (INIS)

    As part of the programme for the final disposal of spent nuclear fuel, an analysis has been compiled of water leakage mapping performed in ONKALO. Leakage mapping is part of the Olkiluoto Monitoring Programme (OMO) and the field work has been carried out by Posiva Oy. The main objective of the study is to analyse differences detected between mapping campaigns carried out typically twice a year in 2005-2012. Differences were estimated to be caused by the differences in groundwater conditions caused by seasonal effects or by differences between the years. The effect of technical changes like shotcreting, postgrouting, ventilation etc. on the results was also studied. The development of the visualisation of mapping results was also an objective of this work. Leakage mapping results have been reported yearly in the monitoring reports of Hydrology with some brief comments on the detected differences. In this study, the development of the total area and the number of different leakages as well as the correlation of changes with shotcreting and grouting operations were studied. In addition, traces of fractures on tunnel surfaces, and the location of rock bolts and drain pipes were illustrated together with leakage mapping. In water leakage mapping, the tunnel surfaces are visually mapped to five categories: dry, damp, wet, dripping and flowing. Major changes were detected in the total area of damp leakages. It is likely that the increase has been caused by the condensation of warm ventilation air on the tunnel surfaces and the corresponding decrease by the evaporation of moisture into the dry ventilation air. Shotcreting deep in ONKALO may also have decreased the total area of damp leakages. Changes in the total area and number of wet leakages correlate at least near the surface with differences in yearly precipitation. It is possible that strong rains have also caused a temporary increase in wet leakages. Dripping and wet leakages have been observed on average more

  20. Analysis of ONKALO water leakage mapping results

    Energy Technology Data Exchange (ETDEWEB)

    Ahokas, H.; Nummela, J; Turku, J. [Poeyry Finland Oy, Vantaa (Finland)

    2014-04-15

    As part of the programme for the final disposal of spent nuclear fuel, an analysis has been compiled of water leakage mapping performed in ONKALO. Leakage mapping is part of the Olkiluoto Monitoring Programme (OMO) and the field work has been carried out by Posiva Oy. The main objective of the study is to analyse differences detected between mapping campaigns carried out typically twice a year in 2005-2012. Differences were estimated to be caused by the differences in groundwater conditions caused by seasonal effects or by differences between the years. The effect of technical changes like shotcreting, postgrouting, ventilation etc. on the results was also studied. The development of the visualisation of mapping results was also an objective of this work. Leakage mapping results have been reported yearly in the monitoring reports of Hydrology with some brief comments on the detected differences. In this study, the development of the total area and the number of different leakages as well as the correlation of changes with shotcreting and grouting operations were studied. In addition, traces of fractures on tunnel surfaces, and the location of rock bolts and drain pipes were illustrated together with leakage mapping. In water leakage mapping, the tunnel surfaces are visually mapped to five categories: dry, damp, wet, dripping and flowing. Major changes were detected in the total area of damp leakages. It is likely that the increase has been caused by the condensation of warm ventilation air on the tunnel surfaces and the corresponding decrease by the evaporation of moisture into the dry ventilation air. Shotcreting deep in ONKALO may also have decreased the total area of damp leakages. Changes in the total area and number of wet leakages correlate at least near the surface with differences in yearly precipitation. It is possible that strong rains have also caused a temporary increase in wet leakages. Dripping and wet leakages have been observed on average more

  1. Gate leakage mechanisms in strained Si devices

    Science.gov (United States)

    Yan, L.; Olsen, S. H.; Kanoun, M.; Agaiby, R.; O'Neill, A. G.

    2006-11-01

    This work investigates gate leakage mechanisms in advanced strained Si /SiGe metal-oxide-semiconductor field-effect transistor (MOSFET) devices. The impact of virtual substrate Ge content, epitaxial material quality, epitaxial layer structure, and device processing on gate oxide leakage characteristics are analyzed in detail. In state of the art MOSFETs, gate oxides are only a few nanometers thick. In order to minimize power consumption, leakage currents through the gate must be controlled. However, modifications to the energy band structure, Ge diffusion due to high temperature processing, and Si /SiGe material quality may all affect gate oxide leakage in strained Si devices. We show that at high oxide electric fields where gate leakage is dominated by Fowler-Nordheim tunneling, tensile strained Si MOSFETs exhibit lower leakage levels compared with bulk Si devices. This is a direct result of strain-induced splitting of the conduction band states. However, for device operating regimes at lower oxide electric fields Poole-Frenkel emissions contribute to strained Si gate leakage and increase with increasing virtual substrate Ge content. The emissions are shown to predominantly originate from surface roughness generating bulk oxide traps, opposed to Ge diffusion, and can be improved by introducing a high temperature anneal. Gate oxide interface trap density exhibits a dissimilar behavior and is highly sensitive to Ge atoms at the oxidizing surface, degrading with increasing thermal budget. Consequently advanced strained Si /SiGe devices are inadvertently subject to a potential tradeoff between power consumption (gate leakage current) and device reliability (gate oxide interface quality).

  2. Study on Detection Technique for Pipeline Leakage

    Institute of Scientific and Technical Information of China (English)

    李健; 王立坤; 周琰; 靳世久

    2003-01-01

    Pipeline integrity defect is a considerable portion in all the defects. Therefore, the study on detection technique is of great concern to the owners of pipelines. A real-time monitoring system of pipeline defect is established. For unexpected accidents of pipeline leakage, several methods of signal processing, including wavelet analysis are utilized. The leakage can be located accurately in time. This system is applied to many long distance pipelines in China, which has made great contributions to the economy.

  3. Asymmetric gate induced drain leakage and body leakage in vertical MOSFETs with reduced parasitic capacitance

    OpenAIRE

    Gili, E.; Kunz, D.; Uchino, T; Hakim, M. M. A.; De Groot, C. H. (Kees); Ashburn, P.; Hall, S.

    2006-01-01

    Vertical MOSFETs, unlike conventional planar MOSFETs, do not have identical structures at the source and drain, but have very different gate overlaps and geometric configurations. This paper investigates the effect of the asymmetric source and drain geometries of surround-gate vertical MOSFETs on the drain leakage currents in the OFF-state region of operation. Measurements of gate-induced drain leakage (GIDL) and body leakage are carried out as a function of temperature for transistors connec...

  4. Leakage-Resilient Circuits without Computational Assumptions

    DEFF Research Database (Denmark)

    Dziembowski, Stefan; Faust, Sebastian

    2012-01-01

    Physical cryptographic devices inadvertently leak information through numerous side-channels. Such leakage is exploited by so-called side-channel attacks, which often allow for a complete security breache. A recent trend in cryptography is to propose formal models to incorporate leakage into the ......Physical cryptographic devices inadvertently leak information through numerous side-channels. Such leakage is exploited by so-called side-channel attacks, which often allow for a complete security breache. A recent trend in cryptography is to propose formal models to incorporate leakage......: (i) in each observation the leakage is bounded, (ii) different parts of the computation leak independently, and (iii) the randomness that is used for certain operations comes from a simple (non-uniform) distribution. In contrast to earlier work on leakage resilient circuit compilers, which relied...... on computational assumptions, our results are purely information-theoretic. In particular, we do not make use of public key encryption, which was required in all previous works...

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

    Directory of Open Access Journals (Sweden)

    Haitham Akram Altaani

    2013-06-01

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

  6. Performance Characteristics of an Isothermal Freeze Valve

    Energy Technology Data Exchange (ETDEWEB)

    Hailey, A.E.

    2001-08-22

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

  7. Posterior Urethral Valves

    Directory of Open Access Journals (Sweden)

    Steve J. Hodges

    2009-01-01

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

  8. Supramolecular spin valves.

    Science.gov (United States)

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

    2011-07-01

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

  9. 一种大流量手动伺服阀的设计与研究%Design and Research of One Kind Large Flow Manual Servo Valve

    Institute of Scientific and Technical Information of China (English)

    刘宏献

    2015-01-01

    介绍了一种带阀芯位置反馈的二级控制超大流量手动伺服阀,先导阀为手动控制的三通伺服滑阀,主阀为大通径滑阀,可控制不同的通流量,实现执行机构以不同的速度运动。其工作原理是由先导阀控制主阀两端压力油腔的排放油,改变主阀两端的压差,从而实现主阀芯位置的变化。分别对主阀芯进行了动力学分析研究和阀体与阀芯间隙配合的选择分析,设计提高了主阀的动态响应特性,避免阀芯卡死和最大限度降低了内泄漏损失。%Introduced one kind secondary control large flow manual servo valve with valve core position feedback, the lead valve is manual control three way servo valve, the main valve is large diameter valve, can control difference flow. realize the actuator move with difference speed , The working principle is the lead valve control the two ends of main valve release oil, change the pressure difference of the two ends of main valve, to realize the position of main valve core. Do dynamics analytic and study for main valve core and analytic for valve body and valve core clearance fit respectively, design enhanced the dynamic response characteristics of main valve, avoid valve core block and maximum reduce the inner leakage loss.

  10. Innovative Stemless Valve Eliminates Emissions

    Science.gov (United States)

    2008-01-01

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

  11. Latest design of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Kurzhofer, U.; Stolte, J.; Weyand, M.

    1996-12-01

    Babcock Sempell, one of the most important valve manufacturers in Europe, has delivered valves for the nuclear power industry since the beginning of the peaceful application of nuclear power in the 1960s. The latest innovation by Babcock Sempell is a gate valve that meets all recent technical requirements of the nuclear power technology. At the moment in the United States, Germany, Sweden, and many other countries, motor-operated gate and globe valves are judged very critically. Besides the absolute control of the so-called {open_quotes}trip failure,{close_quotes} the integrity of all valve parts submitted to operational forces must be maintained. In case of failure of the limit and torque switches, all valve designs have been tested with respect to the quality of guidance of the gate. The guidances (i.e., guides) shall avoid a tilting of the gate during the closing procedure. The gate valve newly designed by Babcock Sempell fulfills all these characteristic criteria. In addition, the valve has cobalt-free seat hardfacing, the suitability of which has been proven by friction tests as well as full-scale blowdown tests at the GAP of Siemens in Karlstein, West Germany. Babcock Sempell was to deliver more than 30 gate valves of this type for 5 Swedish nuclear power stations by autumn 1995. In the presentation, the author will report on the testing performed, qualifications, and sizing criteria which led to the new technical design.

  12. How to attribute market leakage to CDM projects

    NARCIS (Netherlands)

    Vöhringer, F.; Kuosmanen, T.K.; Dellink, R.B.

    2006-01-01

    Economic studies suggest that market leakage rates of greenhouse gas abatement can reach the two-digit percentage range. Although the Marrakesh Accords require Clean Development Mechanism (CDM) projects to account for leakage, most projects neglect market leakage. Insufficient leakage accounting is

  13. Pickering unit 1 containment leakage characterization

    International Nuclear Information System (INIS)

    Results of the design pressure test carried out on Pickering Reactor Building number 1 during late 1992 showed that the leakage rate of the building was close to the safety analysis value of 2.7% contained mass per hour at the design pressure of 41.4 kPa(g) and was significantly higher than that reported after the previous test conducted in the spring of 1987. This unexpected finding initiated the longest and the most comprehensive containment leakage investigation ever undertaken by Ontario Hydro. A thorough investigation of leakage behaviour by repeated testing, inspections, leak search and analysis was launched. The extensive leak search effort included items such as: leak source detection by soap solution application, use of ultrasonic detectors, fogging and tracer gas techniques, systematic systems isolation, thermal imaging of the exterior, and quantification of leak sites by flowmeter and bagging. Using a specially designed volumetric technique, the root cause of the problem was finally confirmed as being due to 'pressure dependent laminar leakage' through the hairline cracks in the dome concrete. Structural analysis indicated that the thermal gradients and pressure loading combined to cause the cracking early in the structure's operating history and that overall structural integrity has not been compromised. Leakage rate analysis using a new fluid mechanics model augmented by the effect of thermal strains indicated that the leakage could be significantly less under certain transient temperature gradient conditions. Several options for repairing the dome were considered by a multidisciplinary team and it was finally decided to apply a specially engineered multilayer elastomeric coating to the exterior concrete surface. When the unit was re-tested in October 1993, a dramatic ten-fold improvement in leakage rate (down to 0.25%/h at design pressure) was observed. This is lower than even the commissioning results and comparable to the performance of newer units

  14. 14 CFR 121.411 - Qualifications: Check airmen (airplane) and check airmen (simulator).

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Qualifications: Check airmen (airplane) and... § 121.411 Qualifications: Check airmen (airplane) and check airmen (simulator). (a) For the purposes of this section and § 121.413: (1) A check airman (airplane) is a person who is qualified, and...

  15. Whitey Gauge and Root Valves (VPS)

    Energy Technology Data Exchange (ETDEWEB)

    MISKA, C.

    2000-09-03

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

  16. Determination of leakage areas in nuclear piping

    Energy Technology Data Exchange (ETDEWEB)

    Keim, E. [Siemens/KWU, Erlangen (Germany)

    1997-04-01

    For the design and operation of nuclear power plants the Leak-Before-Break (LBB) behavior of a piping component has to be shown. This means that the length of a crack resulting in a leak is smaller than the critical crack length and that the leak is safely detectable by a suitable monitoring system. The LBB-concept of Siemens/KWU is based on computer codes for the evaluation of critical crack lengths, crack openings, leakage areas and leakage rates, developed by Siemens/KWU. In the experience with the leak rate program is described while this paper deals with the computation of crack openings and leakage areas of longitudinal and circumferential cracks by means of fracture mechanics. The leakage areas are determined by the integration of the crack openings along the crack front, considering plasticity and geometrical effects. They are evaluated with respect to minimum values for the design of leak detection systems, and maximum values for controlling jet and reaction forces. By means of fracture mechanics LBB for subcritical cracks has to be shown and the calculation of leakage areas is the basis for quantitatively determining the discharge rate of leaking subcritical through-wall cracks. The analytical approach and its validation will be presented for two examples of complex structures. The first one is a pipe branch containing a circumferential crack and the second one is a pipe bend with a longitudinal crack.

  17. Prosthetic valve endocarditis after transcatheter aortic valve implantation

    DEFF Research Database (Denmark)

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

    2015-01-01

    BACKGROUND: Transcatheter aortic valve implantation (TAVI) is an advancing mode of treatment for inoperable or high-risk patients with aortic stenosis. Prosthetic valve endocarditis (PVE) after TAVI is a serious complication, but only limited data exist on its incidence, outcome, and procedural...... risk factors. METHODS AND RESULTS: Observational single-center study of 509 consecutive patients treated with a transcatheter implanted self-expandable aortic valve prosthesis (Medtronic CoreValve). We identified 18 patients diagnosed with TAVI-PVE during a median follow-up period of 1.4 years......%) were treated conservatively and 1 with surgery. Four patients (22%) died from endocarditis or complications to treatment, 2 of those (11%) during initial hospitalization for PVE. An increased risk of TAVI-PVE was seen in patients with low implanted valve position (hazard ratio, 2.8 [1.1-7.2]), moderate...

  18. Energy reduction through voltage scaling and lightweight checking

    Science.gov (United States)

    Kadric, Edin

    As the semiconductor roadmap reaches smaller feature sizes and the end of Dennard Scaling, design goals change, and managing the power envelope often dominates delay minimization. Voltage scaling remains a powerful tool to reduce energy. We find that it results in about 60% geomean energy reduction on top of other common low-energy optimizations with 22nm CMOS technology. However, when voltage is reduced, it becomes easier for noise and particle strikes to upset a node, potentially causing Silent Data Corruption (SDC). The 60% energy reduction, therefore, comes with a significant drop in reliability. Duplication with checking and triple-modular redundancy are traditional approaches used to combat transient errors, but spending 2--3x the energy for redundant computation can diminish or reverse the benefits of voltage scaling. As an alternative, we explore the opportunity to use checking operations that are cheaper than the base computation they are guarding. We devise a classification system for applications and their lightweight checking characteristics. In particular, we identify and evaluate the effectiveness of lightweight checks in a broad set of common tasks in scientific computing and signal processing. We find that the lightweight checks cost only a fraction of the base computation (0-25%) and allow us to recover the reliability losses from voltage scaling. Overall, we show about 50% net energy reduction without compromising reliability compared to operation at the nominal voltage. We use FPGAs (Field-Programmable Gate Arrays) in our work, although the same ideas can be applied to different systems. On top of voltage scaling, we explore other common low-energy techniques for FPGAs: transmission gates, gate boosting, power gating, low-leakage (high-Vth) processes, and dual-V dd architectures. We do not scale voltage for memories, so lower voltages help us reduce logic and interconnect energy, but not memory energy. At lower voltages, memories become dominant

  19. A review of digital radiography technology for valve inspection

    International Nuclear Information System (INIS)

    There are thousands of valves in a nuclear power plant (NPP) used for control, safety and checks in various plant systems, so there is a well-identified need for fast and reliable inspection and diagnostics of valves. Digital radiography can provide considerable improvements to the inspection and testing procedures for valves in comparison to classical film radiography. These improvements can lead to significant financial advantages by providing real-time inspection results, significantly reduced inspection and decision-making time, and reduced operational cost. Digital image processing, including digital image enhancement, digital archiving, and digital communication of the images and the results, is also a considerable advantage over classical film radiography technology. Another advantage of digital radiography technology is the improved safety and the reduced environmental impact due to reduced exposure/test times, use of smaller exclusion zones, elimination of chemical processing, and absence of disposable materials. This paper reviews the existing technology and evaluates the potential of digital radiography for inspection and diagnostics of valves. Station needs and requirements are assessed, and the safety, environmental and economical constraints of digital radiography techniques estimated. The advantages and disadvantages of different digital radiography equipment are compared, and their limitations and characteristics studied. (author)

  20. High Reliability Cryogenic Piezoelectric Valve Actuator Project

    Data.gov (United States)

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

  1. Anonymity control in electronic check systems

    Institute of Scientific and Technical Information of China (English)

    Ma Chunguang; Yang Yixian; Hu Zhengming

    2005-01-01

    Electronic check systems, as one of electronic payment systems, are more desirable than other electronic cash systems. In the system, only a single check is used to pay any price that is not more than the face value. The main problem in check systems is to design an efficient refund mechanism that makes refund checks undistinguished from initial checks during payment and deposit. The problem of anonymity control also called fairness is also an important issue in check systems. All check systems yet are unconditional anonymity that opens the door to misuse for crime such as laundering and blackmailing. In this paper, the notion of anonymity revocation is introduced to electronic check system for the first time, and a model of fair electronic check system is proposed. An efficient fair online electronic check system with reusable refund is presented. In the system, a passive trustee is employed to revoke the anonymity of un-honest users. Moreover, the system solves the reusability problem of refunds thanks to the RSA-based partially signature. The system is efficient and meets all basic security requirements.

  2. Risk factors of pancreatic leakage after pancreaticoduodenectomy

    Institute of Scientific and Technical Information of China (English)

    Yin-Mo Yang; Xiao-Dong Tian; Yan Zhuang; Wei-Min Wang; Yuan-Lian Wan; Yan-Ting Huang

    2005-01-01

    AIM: To analyze the risk factors for pancreatic leakage after pancreaticoduodenectomy (PD) and to evaluate whether duct-to-mucosa pancreaticojejunostomy could reduce the risk of pancreatic leakage.METHODS: Sixty-two patients who underwent PD at our hospital between January 2000 and November 2003 were reviewed retrospectively. The primary diseases of the patients included pancreas cancer, ampullary cancer, bile duct cancer, islet cell cancer, duodenal cancer, chronic pancreatitis, pancreatic cystadenoma, and gastric cancer.Standard PD was performed for 25 cases, PD with extended lymphadenectomy for 27 cases, pylorus-preserving PD for 10 cases. A duct-to-mucosa pancreaticojejunostomy was performed for patients with a hard pancreas and a dilated pancreatic duct, and a traditional end-to-end invagination pancreaticojejunostomy for patients with a soft pancreas and a non-dilated duct. Patients were divided into two groups according to the incidence of postoperative pancreaticojejunal anastomotic leakage: 10 cases with leakage and 52 cases without leakage. Seven preoperative and six intraoperative risk factors with the potential to affect the incidence of pancreatic leakage were analyzed with SPSS10.0 software. Logistic regression was then used to determine the effect of multiple factors on pancreatic leakage.RESULTS: Of the 62 patients, 10 (16.13%) were identified as having pancreatic leakage after operation. Other major postoperative complications included delayed gastric emptying (eight patients), abdominal bleeding (four patients), abdominal abscess (three patients) and wound infection (two patients). The overall surgical morbidity was 43.5% (27/62). The hospital mortality in this series was 4.84% (3/62), and the mortality associated with pancreatic fistula was 10% (1/10). Sixteen cases underwent duct-to-mucosa pancreaticojejunostomy and 1 case (1/16, 6.25%) devel-oped postoperative pancreatic leakage, 46 cases underwent invagination pancreaticojejunostomy and 9

  3. Study on analysis technology of the leakage current from Power facilities by using the laser technology

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Won Bin; Lee, Bok Kyu; Ohk, Young Hwan [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Han, Min Koo; Seung, Hwang Bo; Kwack, Hee Ro; Kim, Jae Chul [Electrical Engineering and Science Research Institute (Korea, Republic of)

    1995-12-31

    In order to apply the laser technology to the power systems, we widely investigated and analyzed optic fiber technology for signal transmissions, optic-sensor technology for detecting the physical quantum such as mechanical and electrical, and the base technology of laser application. The prototype was designed to detect the whole and the third harmonic current, for the analysis of the leakage current from gapless arrester. Also, the device was designed for portable use and for on-line checking. This prototype enables us to store and analyze the data easily by using the computer. Those stored data can be used as the reference data for estimating the extent of badness by analyzing and evaluating the trend of the leakage current with time. (author). 36 refs., 78 figs.

  4. Air leakage in residential solar heating systems

    Science.gov (United States)

    Shingleton, J. G.; Cassel, D. E.; Overton, R. L.

    1981-02-01

    A series of computer simulations was performed to evaluate the effects of component air leakage on system thermal performance for a typical residential solar heating system, located in Madison, Wisconsin. Auxiliary energy required to supplement solar energy for space heating was determined using the TRNSYS computer program, for a range of air leakage rates at the solar collector and pebble bed storage unit. The effects of heat transfer and mass transfer between the solar equipment room and the heated building were investigated. The effect of reduced air infiltration into the building due to pressurized by the solar air heating system were determined. A simple method of estimating the effect of collector array air leakage on system thermal performance was evaluated, using the f CHART method.

  5. Survey on Techniques for Detecting Data Leakage

    Directory of Open Access Journals (Sweden)

    Bhosale Pranjali A

    2016-06-01

    Full Text Available In current business scenario, critical data is to be shared and transferred by organizations to many stake holders in order to complete particular task. The critical data include intellectual copyright, patient information etc. The activities like sharing and transferring of such critical data includes threats like leakage of information, misuse of data, illegal access to data and/or alteration of data. It is necessary to deal with such problem efficiently and effectively, popular solutions to this problem are use of firewalls, data loss prevention tools and watermarking. But sometimes culprit succeeds in overcoming such security measures hence, if organizations becomes able to find out the guilty client responsible for leakage of particular data then risk of data leakage is reduced. For this many systems are proposed, this paper includes information about techniques discussed in some of such methodologies.

  6. Leakage current measurement in transformerless PV inverters

    DEFF Research Database (Denmark)

    Kerekes, Tamas; Sera, Dezso; Mathe, Laszlo

    2012-01-01

    Photovoltaic (PV) installations have seen a huge increase during the last couple of years. Transformerless PV inverters are gaining more share of the total inverter market, due to their high conversion efficiency, small weight and size. Nevertheless safety should have an important role in case...... of these tranformerless systems, due to the missing galvanic isolation. Leakage and fault current measurement is a key issue for these inverter topologies to be able to comply with the required safety standards. This article presents the test results of two different current measurement sensors that were suggested...... to be used in commercial PV inverters for the measurement of leakage and fault ground currents. The German VDE0126–1–1 standard gives the limit for fault and leakage ground currents and all grid connected PV inverters have to comply with these limits and disconnect from the grid in case of a fault....

  7. Markovian Processes for Quantitative Information Leakage

    DEFF Research Database (Denmark)

    Biondi, Fabrizio

    and randomized processes with Markovian models and to compute their information leakage for a very general model of attacker. We present the QUAIL tool that automates such analysis and is able to compute the information leakage of an imperative WHILE language. Finally, we show how to use QUAIL to analyze some......Quantification of information leakage is a successful approach for evaluating the security of a system. It models the system to be analyzed as a channel with the secret as the input and an output as observable by the attacker as the output, and applies information theory to quantify the amount...... of information transmitted through such channel, thus effectively quantifying how many bits of the secret can be inferred by the attacker by analyzing the system’s output. Channels are usually encoded as matrices of conditional probabilities, known as channel matrices. Such matrices grow exponentially...

  8. A discussion of system reliability and the relative importance of pumps and valves to overall system availability

    Energy Technology Data Exchange (ETDEWEB)

    Poole, A.B. [Oak Ridge National Lab., TN (United States)

    1996-12-01

    An analysis was undertaken to establish preliminary trends for how component aging can effect failure rates for swing check valves, centrifugal pumps and motor operated valves. These failure rate trends were evaluated over time and linear aging rate models established. The failure rate models were then used with classic reliability theories to estimate reliability as a function of operating time. Reliability theory was also used to establish a simple system reliability model. Using the system model, the relative importance of pumps and valves to the overall system reliability were studied. Conclusions were established relative to overall system availability over time and the relative unavailabilities of the various components studied.

  9. Valve-"Health"-Monitoring System

    Science.gov (United States)

    Jensen, Scott L.; Drouant, George J.

    2009-01-01

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

  10. Surge-damping vacuum valve

    Science.gov (United States)

    Bullock, Jack C.; Kelly, Benjamin E.

    1980-01-01

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

  11. Variable gas leak rate valve

    Science.gov (United States)

    Eernisse, Errol P.; Peterson, Gary D.

    1976-01-01

    A variable gas leak rate valve which utilizes a poled piezoelectric element to control opening and closing of the valve. The gas flow may be around a cylindrical rod with a tubular piezoelectric member encircling the rod for seating thereagainst to block passage of gas and for reopening thereof upon application of suitable electrical fields.

  12. Combination throttle and shutoff valve

    Science.gov (United States)

    Carriker, J. W.

    1972-01-01

    Combination of translating sleeve throttle valve and conventional poppet valve provides capability of shutting off flow completely by poppet and sleeve control of the rate of flow. Integration of the two concepts can be accomplished without difficulty and in a manner that requires a minimum of development.

  13. What Causes Heart Valve Disease?

    Science.gov (United States)

    ... other infections with strep bacteria that progress to rheumatic fever can cause heart valve disease. When the body tries to fight the strep ... you feel better before the medicine is gone. Heart valve disease caused by rheumatic fever mainly affects older adults who had strep ...

  14. A Study on the Evaluation of Valve Leak Rates Using Acoustic Emission Technique

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Guk; Lee, Jun Shin; Lee, Sun Ki; Shon, Seok Man; Lee, Wook Ryun; Kim, Tae Ryong [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Lim, Yong Jae; Choo, Kee Young [Hana Evertech Co., Seongnam (Korea, Republic of)

    2005-07-01

    The objective of this study is to estimate the feasibility of acoustic emission method for the internal leak from the valves. In this study, two types of valve(a 3 1/2 inch glove valve for 600 psi steam and a 4 inch ball valve water ) leak tests using three different leak path and numerous leak rates were performed in order to analyze acoustic emission properties when leaks arise in valve seat. As a result of leak test for specimens simulated valve seat, we conformed that leak sound amplitude increased in proportion to the increase of leak rate, and leak rates were plotted versus peak acoustic amplitudes recorded within those two narrow frequency bands on each spectral plot. The resulting plots of leak rate versus peak acoustic amplitude were the primary basis for determining the feasibility of quantifying leak acoustically. The large amount of data collected also allowed a grief investigation of the effects of different leak paths, leakage rates, pressure differentials and transducers on the acoustic amplitude spectra. From the experimental results, it was suggested that the acoustic emission method for monitoring of leak was feasible.

  15. 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 valve 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...

  16. Robotic mitral valve surgery.

    Science.gov (United States)

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

    2003-12-01

    A renaissance in cardiac surgery has begun. The early clinical experience with computer-enhanced telemanipulation systems outlines the limitations of this approach despite some procedural success. Technologic advancements, such as the use of nitinol U-clips (Coalescent Surgical Inc., Sunnyvale, CA) instead of sutures requiring manual knot tying, have been shown to decrease operative times significantly. It is expected that with further refinements and development of adjunct technologies, the technique of computer-enhanced endoscopic cardiac surgery will evolve and may prove to be beneficial for many patients. Robotic technology has provided benefits to cardiac surgery. With improved optics and instrumentation, incisions are smaller. The ergometric movements and simulated three-dimensional optics project hand-eye coordination for the surgeon. The placement of the wristlike articulations at the end of the instruments moves the pivoting action to the plane of the mitral annulus. This improves dexterity in tight spaces and allows for ambidextrous suture placement. Sutures can be placed more accurately because of tremor filtration and high-resolution video magnification. Furthermore, the robotic system may have potential as an educational tool. In the near future, surgical vision and training systems might be able to model most surgical procedures through immersive technology. Thus, a "flight simulator" concept emerges where surgeons may be able to practice and perform the operation without a patient. Already, effective curricula for training teams in robotic surgery exist. Nevertheless, certain constraints continue to limit the advancement to a totally endoscopic computer-enhanced mitral valve operation. The current size of the instruments, intrathoracic instrument collisions, and extrathoracic "elbow" conflicts still can limit dexterity. When smaller instruments are developed, these restraints may be resolved. Furthermore, a working port incision is still required for

  17. Heteroscedasticity checks for regression models

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    For checking on heteroscedasticity in regression models, a unified approach is proposed to constructing test statistics in parametric and nonparametric regression models. For nonparametric regression, the test is not affected sensitively by the choice of smoothing parameters which are involved in estimation of the nonparametric regression function. The limiting null distribution of the test statistic remains the same in a wide range of the smoothing parameters. When the covariate is one-dimensional, the tests are, under some conditions, asymptotically distribution-free. In the high-dimensional cases, the validity of bootstrap approximations is investigated. It is shown that a variant of the wild bootstrap is consistent while the classical bootstrap is not in the general case, but is applicable if some extra assumption on conditional variance of the squared error is imposed. A simulation study is performed to provide evidence of how the tests work and compare with tests that have appeared in the literature. The approach may readily be extended to handle partial linear, and linear autoregressive models.

  18. Control-flow checking via regular expressions

    OpenAIRE

    Benso, Alfredo; Di Natale, Giorgio; Di Carlo, Stefano; Prinetto, Paolo Ernesto; Tagliaferri, Luca

    2001-01-01

    The present paper explains a new approach to program control flow checking. The check has been inserted at source-code level using a signature methodology based on regular expressions. The signature checking is performed without a dedicated watchdog processor but resorting to inter-process communication (IPC) facilities offered by most of the modern operating systems. The proposed approach allows very low memory overhead and trade-off between fault latency and program execution time overhead

  19. Valve-related complications after mechanical heart valve implantation.

    Science.gov (United States)

    Misawa, Yoshio

    2015-10-01

    The number of heart valve surgeries is increasing, and 19,164 patients underwent heart valve surgery in Japan in 2011. The early mortality rate has remained stable for more than 10 years. Many patients now survive for many years, with a reported 10-year survival rate of at least 60 %. However, unfavorable complications can occur after valve surgery. Valve-related complications include thromboembolisms, bleeding complications and prosthetic valve endocarditis, followed by structural and nonstructural prosthetic valve dysfunctions. Our review of studies published after 2000 revealed that the rate of all valve-related complications was 0.7-3.5 % per patient-year. Thromboembolisms occur at a rate of approximately 1 % per patient-year, and bleeding complications occur at almost 0.5 % per patient-year. Thromboembolic and hemorrhagic events related to anticoagulant therapy should be considered during life-long follow-up. The occurrence rate of endocarditis reaches 0.5 % per patient-year, with a poor postoperative survival. Structural dysfunctions have been largely overcome, and the nonstructural dysfunction rate is 0.4-1.2 % per patient-year. The nonstructural dysfunctions induced by paravalvular leaks and pannus ingrowth are also issues that need to be resolved.

  20. Patents and heart valve surgery - II: tissue valves.

    Science.gov (United States)

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

    2013-08-01

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

  1. Surgical treatment of mitral valve insufficiency by valve repair

    Directory of Open Access Journals (Sweden)

    Murad Henrique

    2002-01-01

    Full Text Available OBJECTIVE: To analyze the short term results of mitral valve repair in a consecutive series of mitral insufficiency patients from different ethiologies. METHODS: A retrospective study was made of 86 patients with mitral insufficiency operated on between May 1992 and May 2001 for mitral valve repair. Mitral insufficiency was severe in 77 patients and moderate in 9. The functional class of the patients was I in 4, II in 48, III in 29 and IV in 5 patients. The etiology was rheumatic in 47 (54.6% cases. RESULTS: Mitral valve repair was performed by only one procedure on the mitral valve in 6 patients, two procedures in 29, and three or more procedures in 51 (59.3% patients. Mitral annuloplasty was performedin 81 patients, with the Braile posterior pericardial ring being the mostcommonly used (87.2%. Hospital mortality was 3.5%. There was improvement in the funcional class in 79 (91.8% patients. Mitral valve function was normal in 80 (93% patients and moderate mitral insufficiency occurred in 6 patients. CONCLUSION: Mitral valve repair can be performed with low mortality (3.5% and high probability of valve function recovery (93%. It should be the procedure of choice in patients with mitral insufficiency.

  2. Patents and heart valve surgery - II: tissue valves.

    Science.gov (United States)

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

    2013-08-01

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

  3. Self-Rupturing Hermetic Valve

    Science.gov (United States)

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

    2011-01-01

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

  4. Giant Thoracic Aneurysm Following Valve Replacement for Bicuspid Aortic Valve.

    Science.gov (United States)

    Tran, Cao; Ul Haq, Ehtesham; Nguyen, Ngoc; Omar, Bassam

    2015-01-01

    Bicuspid aortic valve is a common congenital anomaly associated with aortopathy, which can cause aortic root dilatation, necessitating regular screening if the aortic root is > 4.0 cm. Despite the low absolute incidence of aortic complications associated with bicuspid aortic valve in the general population, the consequences of such complications for an individual patient can be devastating. Herein we propose a balanced algorithm that incorporates recommendations from the three major guidelines for follow-up imaging of the aortic root and ascending thoracic aorta in patients with a bicuspid aortic valve, maintaining the current recommendations with regard to surgical thresholds. PMID:26827748

  5. Transcatheter Aortic Valve Replacement in Bicuspid Aortic Valve Disease

    DEFF Research Database (Denmark)

    Mylotte, Darren; Lefevre, Thierry; Søndergaard, Lars;

    2014-01-01

    BACKGROUND: Limited information exists describing the results of transcatheter aortic valve (TAV) replacement in patients with bicuspid aortic valve (BAV) disease (TAV-in-BAV). OBJECTIVES: This study sought to evaluate clinical outcomes of a large cohort of patients undergoing TAV-in-BAV. METHODS......: We retrospectively collected baseline characteristics, procedural data, and clinical follow-up findings from 12 centers in Europe and Canada that had performed TAV-in-BAV. RESULTS: A total of 139 patients underwent TAV-in-BAV with the balloon-expandable transcatheter heart valve (THV) (n = 48...

  6. Factors Contributing to Pilot Valve Fuel Seal Extrusion in Orbiter PRCS Thrusters

    Science.gov (United States)

    Waller, J.M.; Saulsberry, R.L.; Albright, John D.

    2000-01-01

    Extrusion of the polytetrafluoroethylene (PTFE) pilot seal used in the monomethylhydrazine (fuel) valve of the Orbiter Primary Reaction Control System (PRCS) thrusters has been implicated in numerous on-orbit thruster failures and on-ground valve failures. Two extrusion mechanisms have been proposed, one or both may be occurring. The first mechanism is attributed to thermal expansion mismatch between adjacent PTFE and metal parts used in the fuel valve, and is referred to as thermal extrusion. The second mechanism is attributed to nitrogen tetroxide (oxidizer) leakage from the adjacent oxidizer valve on the same thruster during ground turnaround, and is referred to as oxidizer-induced extrusion. Model calculations of PTFE pilot seal in an exact pilot valve configuration show that extrusion can be caused by differential thermal expansion, without the intervening influence of oxidizer. Experimental data on semitrapped PTFE and TFM (modified PTFE) specimens simulating a fuel pilot valve configuration show that thermal extrusion 1) is incremental and irreversible, 2) increases with the size of the thermal excursion, 3) decreases with successive thermal cycling, and 4) is accompanied by gap formation. Both PTFE and TFM exhibit a higher affinity for oxidizer than fuel. The property changes associated with oxidizer uptake may explain why oxidizer seals do not exhibit extrusion. Impression replicas of fuel pilot seals removed from the Orbiter fleet show two types of extrusion: extrusion of the entire seal (loaded extrusion), or extrusion of non-sealing surface (unloaded extrusion). Both extrusion types may arise from differences in service history, rather than in failure mechanism. The plausibility oxidizer-induced extrusion was evaluated. Preliminary calculations suggest that enough energy, heat, or gas may be liberated under certain operational scenarios to cause catastrophic extrusion. However, given the lack of supporting data, conclusions implicating oxidizer leakage

  7. 14 CFR 91.1093 - Initial and transition training and checking: Check pilots (aircraft), check pilots (simulator).

    Science.gov (United States)

    2010-01-01

    ... OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Fractional Ownership Operations Program Management § 91... preceding 24 months, that person satisfactorily conducts a proficiency or competency check under the..., and emergency procedures to ensure competence to conduct the pilot flight checks required by...

  8. Twenty-Two-Year Experience with Aortic Valve Replacement: Starr-Edwards Ball Valves versus Disc Valves

    OpenAIRE

    Pilegaard, Hans K.; Lund, Ole; Nielsen, Torsten T; Magnussen, Karin; Knudsen, Mary A; Albrechtsen, Ole K.

    1991-01-01

    From 1965 through 1986, 817 patients underwent aortic valve replacement at our institution. Six hundred forty-five patients received Starr-Edwards ball valves, including 286 Silastic ball valves (Models 1200/1260), 165 cloth-covered caged-ball prostheses (Models 2300/2310/2320), and 194 track-valve prostheses (Model 2400). In contrast, 172 patients received disc-valve prostheses, including 126 St. Jude Medical aortic bi-leaflet disc valves, 32 Lillehei-Kaster pivoting disc valves, and 14 Björ...

  9. Quantifying information leakage of randomized protocols

    DEFF Research Database (Denmark)

    Biondi, Fabrizio; Legay, Axel; Malacaria, Pasquale;

    2015-01-01

    The quantification of information leakage provides a quantitative evaluation of the security of a system. We propose the usage of Markovian processes to model deterministic and probabilistic systems. By using a methodology generalizing the lattice of information approach we model refined attacker...

  10. Poloidal field leakage optimization in ETE

    International Nuclear Information System (INIS)

    A very simple but efficient numerical algorithm is used to minimize the Ohmic coil field leakage into the plasma region of the tokamak ETE. After few interactions the code provides the positions and the current required for two pairs of compensation coils. Resulting optimum field intensity distribution is presented and commented. (author). 5 refs., 4 figs., 2 tabs

  11. Prediction of sodium leakage and combustion phenomena

    International Nuclear Information System (INIS)

    Prediction of sodium leakage and combustion phenomena is important for the safety of liquid metal fast breeder reactors. In particular, small leakage is sensitive to obstacles and air flows. Falling liquid sodium is strongly deformed by separation and dispersion as well as various phenomena, such as combustion and accumulation, are combined. Since the existing finite difference methods need computational grids, it is so difficult to calculate separation and dispersion that small leakage of liquid sodium cannot be analyzed. MPS (Moving Particle Semi-implicit) method is a new numerical method, which is being developed in Univ of Tokyo. In the MPS method fluids are represented by macroscopic particles and governing equations are converted to equivalent particle interactions. Since computational grids are not necessary, separation and dispersion of fluids are easily calculated. Addition of combustion and accumulation will be easy as well because the fluid motion is just simulated by the particle motion. Thus, the objective of the present study is development of a numerical method to predict small size sodium leakage and combustion phenomena. In this paper, a model experiment using water and numerical calculations for this experiment are presented. (J.P.N.)

  12. PWR safety and relief valve test program. Valve selection/juftification report. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1982-12-01

    NUREG 0578 required that full-scale testing be performed on pressurizer safety valves and relief valves representative of those in use or planned for use in PWR plants. To obtain valve performance data for the entire population of PWR plant valves, nine safety valves and ten relief valves were selected as a fully representative set of test valves. Justification that the selected valves represent all PWR plant valves was provided by each safety and relief valve manufacturer. Both the valve selection and justification work was performed as part of the PWR Safety and Relief Valve Test Program conducted by EPRI on behalf of the PWR utilities in response to the recommendations of NUREG 0578 and the requirements of the NRC. Results of the Safety and Relief Valve Selection and Justification effort is documented in this report.

  13. Heteroscedasticity checks for regression models

    Institute of Scientific and Technical Information of China (English)

    ZHU; Lixing

    2001-01-01

    [1]Carroll, R. J., Ruppert, D., Transformation and Weighting in Regression, New York: Chapman and Hall, 1988.[2]Cook, R. D., Weisberg, S., Diagnostics for heteroscedasticity in regression, Biometrika, 1988, 70: 1—10.[3]Davidian, M., Carroll, R. J., Variance function estimation, J. Amer. Statist. Assoc., 1987, 82: 1079—1091.[4]Bickel, P., Using residuals robustly I: Tests for heteroscedasticity, Ann. Statist., 1978, 6: 266—291.[5]Carroll, R. J., Ruppert, D., On robust tests for heteroscedasticity, Ann. Statist., 1981, 9: 205—209.[6]Eubank, R. L., Thomas, W., Detecting heteroscedasticity in nonparametric regression, J. Roy. Statist. Soc., Ser. B, 1993, 55: 145—155.[7]Diblasi, A., Bowman, A., Testing for constant variance in a linear model, Statist. and Probab. Letters, 1997, 33: 95—103.[8]Dette, H., Munk, A., Testing heteoscedasticity in nonparametric regression, J. R. Statist. Soc. B, 1998, 60: 693—708.[9]Müller, H. G., Zhao, P. L., On a semi-parametric variance function model and a test for heteroscedasticity, Ann. Statist., 1995, 23: 946—967.[10]Stute, W., Manteiga, G., Quindimil, M. P., Bootstrap approximations in model checks for regression, J. Amer. Statist. Asso., 1998, 93: 141—149.[11]Stute, W., Thies, G., Zhu, L. X., Model checks for regression: An innovation approach, Ann. Statist., 1998, 26: 1916—1939.[12]Shorack, G. R., Wellner, J. A., Empirical Processes with Applications to Statistics, New York: Wiley, 1986.[13]Efron, B., Bootstrap methods: Another look at the jackknife, Ann. Statist., 1979, 7: 1—26.[14]Wu, C. F. J., Jackknife, bootstrap and other re-sampling methods in regression analysis, Ann. Statist., 1986, 14: 1261—1295.[15]H rdle, W., Mammen, E., Comparing non-parametric versus parametric regression fits, Ann. Statist., 1993, 21: 1926—1947.[16]Liu, R. Y., Bootstrap procedures under some non-i.i.d. models, Ann. Statist., 1988, 16: 1696—1708.[17

  14. Cavitation guide for control valves

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-04-01

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

  15. Cavitation guide for control valves

    International Nuclear Information System (INIS)

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

  16. Successful thrombolysis for prosthetic pulmonary valve obstruction.

    OpenAIRE

    Lopez, J. A.; Strickman, N E; Jin, B S; X. G. Li; Phan, B; Zeluff, B J; Wilansky, S

    1995-01-01

    Thrombosis is a serious complication of prosthetic heart valve operations. In recent years, systemic thrombolysis has emerged as a suitable alternative to surgery. Experience with thrombosis of pulmonary prosthetic valves is very limited. We report a case of successful administration of intravenous streptokinase for thrombosis of a St. Jude Medical prosthetic valve 3 weeks after pulmonary valve replacement.

  17. 49 CFR 195.260 - Valves: Location.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves: Location. 195.260 Section 195.260... PIPELINE Construction § 195.260 Valves: Location. A valve must be installed at each of the following... Administrator finds in a particular case that valves are not justified. (f) On each side of a reservoir...

  18. 49 CFR 195.116 - Valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves. 195.116 Section 195.116 Transportation... PIPELINE Design Requirements § 195.116 Valves. Each valve installed in a pipeline system must comply with the following: (a) The valve must be of a sound engineering design. (b) Materials subject to...

  19. 14 CFR 125.133 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Fuel valves. 125.133 Section 125.133....133 Fuel valves. Each fuel valve must— (a) Comply with § 125.155; (b) Have positive stops or suitable... operation or from accelerated flight conditions are not transmitted to the lines connected to the valve....

  20. 49 CFR 192.145 - Valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves. 192.145 Section 192.145 Transportation... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Design of Pipeline Components § 192.145 Valves. (a) Except for cast iron and plastic valves, each valve must meet the minimum requirements of API...

  1. 14 CFR 125.137 - Oil valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  2. 49 CFR 229.109 - Safety valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Safety valves. 229.109 Section 229.109....109 Safety valves. Every steam generator shall be equipped with at least two safety valves that have a... allowed working pressure. The safety valves shall be independently connected to the separator and...

  3. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market. In this project, the ARIES team sought to better understand the current usage of TRVs by key market players in steam and hot water heating and to conduct limited experiments on the effectiveness of new and old TRVs as a means of controlling space temperatures and reducing heating fuel consumption. The project included a survey of industry professionals, a field experiment comparing old and new TRVs, and cost-benefit modeling analysis using BEopt™ (Building Energy Optimization software).

  4. Ferroelectric Fluid Flow Control Valve

    Science.gov (United States)

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

    1999-01-01

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

  5. Tractor Mechanic Check Sheets for Modules.

    Science.gov (United States)

    Clemson Univ., SC. Vocational Education Media Center.

    Forms for student self-checks and the instructor's final checklist (student evaluation) are provided for use with thirty-three learning modules on maintaining and servicing fuel and electrical systems in tractor mechanics. The student self-check asks the students questions about their understanding of the modules' content. The instructor's…

  6. The model checking fingerprints of CTL operators

    OpenAIRE

    Krebs, Andreas; Meier, Arne; Mundhenk, Martin

    2015-01-01

    The aim of this study is to understand the inherent expressive power of CTL operators. We investigate the complexity of model checking for all CTL fragments with one CTL operator and arbitrary Boolean operators. This gives us a fingerprint of each CTL operator. The comparison between the fingerprints yields a hierarchy of the operators that mirrors their strength with respect to model checking.

  7. 25 CFR 141.19 - Check cashing.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Check cashing. 141.19 Section 141.19 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR FINANCIAL ACTIVITIES BUSINESS PRACTICES ON THE NAVAJO, HOPI AND ZUNI RESERVATIONS General Business Practices § 141.19 Check cashing. (a) A reservation...

  8. 7 CFR 58.243 - Checking quality.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Checking quality. 58.243 Section 58.243 Agriculture... Procedures § 58.243 Checking quality. All milk, milk products and dry milk products shall be subject to inspection and analysis by the dairy plant for quality and condition throughout each processing...

  9. Automatization and familiarity in repeated checking

    NARCIS (Netherlands)

    Dek, E.C.P.; van den Hout, M.A.; Giele, C.L.; Engelhard, I.M.

    2015-01-01

    Repetitive, compulsive-like checking of an object leads to reductions in memory confidence, vividness, and detail. Experimental research suggests that this is caused by increased familiarity with perceptual characteristics of the stimulus and automatization of the checking procedure (Dek, van den Ho

  10. SPEED ROLLER STAND MEASUREMENT SYSTEM CHECKING TECHNIQUE

    OpenAIRE

    Zybtsev, Y.; I. Marmut

    2011-01-01

    The study has shown that the accuracy of brakes checking by inertial stands depends upon the applied methods of measurement of braking parameters (stand slowing down, braking distance, brakes triggering time, current speed) as well as the methods of metrological checking of measuring system canals.

  11. 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.

  12. Performance-based improvement of the leakage rate test program for the reactor containment of HTTR. Adoption of revised test programs containing 'Type A, Type B and Type C tests'

    International Nuclear Information System (INIS)

    The reactor containment of HTTR is periodically tested to confirm leak-tight integrity by conducting overall integrated leakage rate tests, so-called 'Type A tests,' in accordance with a standard testing method provided in Japan Electric Association Code (JEAC) 4203. 'Type A test' is identified as a basic one for measuring whole leakage rates for reactor containments, it takes, however, much of cost and time of preparation, implementation and restoration of itself. Therefore, in order to upgrade the maintenance technology of HTTR, the containment leakage rate test program for HTTR was revised by adopting efficient and economical alternatives including Type B and Type C tests' which intend to measure leakage rates for containment penetrations and isolation valves, respectively. In JEAC4203-2004, following requirements are specified for adopting an alternative program: upward trend of the overall integrated leakage rate due to aging affection should not be recognized; performance criterion for combined leakage rate, that is a summation of local leakage rates evaluated by Type B and Type C tests and converted to whole leakage rates, should be established; the criterion of the combined leakage rate should be satisfied as well as of the overall integrated leakage rate; correlation between the overall integrated and combined leakage rates should be recognized. Considering the historical performances, policies of conforming to the forgoing requirements and of carrying out the revised test program were developed, which were accepted by the regulatory agency. This report presents an outline of the leakage rate tests for the reactor containment of HTTR, identifies practical issues of conventional Type A tests, and describes the conforming and implementing policies mentioned above. (author)

  13. QuickChecking Static Analysis Properties

    DEFF Research Database (Denmark)

    Midtgaard, Jan; Møller, Anders

    2015-01-01

    A static analysis can check programs for potential errors. A natural question that arises is therefore: who checks the checker? Researchers have given this question varying attention, ranging from basic testing techniques, informal monotonicity arguments, thorough pen-and-paper soundness proofs......, to verified fixed point checking. In this paper we demonstrate how quickchecking can be useful for testing a range of static analysis properties with limited effort. We show how to check a range of algebraic lattice properties, to help ensure that an implementation follows the formal specification...... of a lattice. Moreover, we offer a number of generic, type-safe combinators to check transfer functions and operators on lattices, to help ensure that these are, e.g., monotone, strict, or invariant. We substantiate our claims by quickchecking a type analysis for the Lua programming language...

  14. Arithmetic Operand Ordering for Equivalence Checking

    Institute of Scientific and Technical Information of China (English)

    WENG Yanling; GE Haitong; YAN Xiaolang; Ren Kun

    2007-01-01

    An information extraction-based technique is proposed for RTL-to-gate equivalence checking. Distances are calculated on directed acyclic graph (AIG). Multiplier and multiplicand are distinguished on multiplications with different coding methods, with which the operand ordering/grouping information could be extracted from a given implementation gate netlist, helping the RTL synthesis engine generate a gate netlist with great similarity. This technique has been implemented in an internal equivalence checking tool, ZD_VIS. Compared with the simple equivalence checking, the speed is accelerated by at least 40% in its application to a class of arithmetic designs, addition and multiplication trees. The method can be easily incorporated into existing RTL-to-gate equivalence checking frameworks, increasing the robustness of equivalence checking for arithmetic circuits.

  15. Mechanical heart valve cavitation in patients with bileaflet valves.

    Science.gov (United States)

    Johansen, Peter; Andersen, Tina S; Hasenkam, J Michael; Nygaard, Hans; Paulsen, Peter K

    2014-01-01

    Today, the quality of mechanical heart valves is quite high, and implantation has become a routine clinical procedure with a low operative mortality (valves are thought of having higher cavitation potential than bileaflet valves due to higher closing velocities. However, the thromboembolic potential seems to be the same. Further studies are therefore needed to investigate the cavitation potential of bileaflet valves in vivo. The post processing of HFPF have shown difficulties when applied on bileaflet vavles due to asynchronous closure of the two leaflets. The aim of this study was therefore to isolate the pressure signature from each leaflet closure and perform cavitation analyses on each component. Six patients were included in the study (St. Jude Medical (n=3) and CarboMedics (n=3); all aortic bileaflet mechanical heart valves). HFPFs were recorded intraoperatively through a hydrophone at the aortic root. The pressure signature relating to the first and second leaflet closure was isolated and cavitation parameters were calculated (RMS after 50 kHz highpass filtering and signal energy). Data were averaged over 30 heart cycles. For all patients both the RMS value and signal energy of the second leaflet closure were higher than for the first leaflet closure. This indicates that the second leaflet closure is most prone to cause cavitation. Therefore, quantifying cavitation based on the HFPF related to the second leaflet closure may suggest that the cavitation potential for bileaflet valves in vivo may be higher than previous studies have suggested. PMID:25571278

  16. Safety Testing of Left Ventricular Vent Valves

    OpenAIRE

    Gavin, Caroline; Coblentz, John; Acsell, Jeffrey R.; Shackelford, Anthony G.; Sistino, Joseph J.

    2015-01-01

    Vent vacuum relief valves (VRVs) are used to limit the negative pressure at the ventricular vent catheter tip as well as prevent reversal of blood flow and prevention of air embolism. The purpose of this study was to evaluate the performance of three commercially available ventricular vent valves. The negative pressure at which the vent valve opened was measured at the valve inlet using high-fidelity pressure transducers. Also, the flow rate at which air entrainment occurred due to valve open...

  17. 14 CFR 135.337 - Qualifications: Check airmen (aircraft) and check airmen (simulator).

    Science.gov (United States)

    2010-01-01

    ... check airmen (simulator). 135.337 Section 135.337 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... (simulator). (a) For the purposes of this section and § 135.339: (1) A check airman (aircraft) is a person who is qualified to conduct flight checks in an aircraft, in a flight simulator, or in a...

  18. 14 CFR 91.1089 - Qualifications: Check pilots (aircraft) and check pilots (simulator).

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Qualifications: Check pilots (aircraft) and check pilots (simulator). 91.1089 Section 91.1089 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... RULES Fractional Ownership Operations Program Management § 91.1089 Qualifications: Check...

  19. Thermodynamic Characteristic Study of a High-temperature Flow-rate Control Valve for Fuel Supply of Scramjet Engines

    Institute of Scientific and Technical Information of China (English)

    ZENG Wen; TONG Zhizhong; LI Songjing; LI Hongzhou; ZHANG Liang

    2012-01-01

    Thermodynamic characteristics are of great importance for the performance of a high-temperature flow-rate control valve,as high-temperature environment may bring problems,such as blocking of spool and increasing of leakage,to the valve.In this paper,a high-temperature flow-rate control valve,pilot-controlled by a pneumatic servo system is developed to control the fuel supply for scramjet engines.After introducing the construction and working principle,the thermodynamic mathematical models of the valve are built based on the heat transfer methods inside the valve.By using different boundary conditions,different methods of simulations are carried out and compared.The steady-state and transient temperature field distribution inside the valve body are predicted and temperatures at five interested points are measured.By comparing the simulation and experimental results,a reasonable 3D finite element analysis method is suggested to predict the thermodynamic characteristics of the high-temperature flow-rate control valve.

  20. Platelet function alterations in dengue are associated with plasma leakage

    NARCIS (Netherlands)

    Michels, M.; Alisjahbana, B.; Groot, P.G. de; Indrati, A.R.; Fijnheer, R.; Puspita, M.; Dewi, I.M.; Wijer, L. van de; Boer, E.M. de; Roest, M.; Ven, A.J. van der; Mast, Q. de

    2014-01-01

    Severe dengue is characterised by thrombocytopenia, plasma leakage and bleeding. Platelets are important for preservation of endothelial integrity. We hypothesised that platelet activation with secondary platelet dysfunction contribute to plasma leakage. In adult Indonesian patients with acute dengu

  1. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... see we've used the cautery to achieve access to the sternum. On the left hand side ... wound, which allows us to get more ready access to the aorta and the aortic valve. The ...

  2. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... a rare problem where the patient's own immune system will attack cardiac valve structures, causing them to ... it be heart, lung et cetera, the immune system recognizes those living issues as not being from ...

  3. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... conditions or other significant medical problems, the American College of Cardiology recommends aortic valve replacement for basically ... more likely we see aortic stenosis. Again, patient education is part of the evaluation and management of ...

  4. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... as represented by the red and the blue color. Typically, blood flowing through a valve should be ... and smooth. We shouldn't see very much color such as we're seeing here. To the ...

  5. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... heart valve which is made out of pyrolitic carbon, basically metal and plastic. Again, blood flows through ... heart surgery here, we actually insufflate, or instill carbon dioxide gas into the field, which we think ...

  6. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... Winkley nor myself have any financial or professional relationships with the manufacturers or the devices used in ... John, just to interrupt for moment, Charles, Charles V., asks can the mitral valve also be replaced ...

  7. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... Jim. Those are coming. There are several valve companies in this country and in Europe that have ... that we've had customized by an instrument company for this approach that really works nicely for ...

  8. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... surgery. I think as physicians we owe a responsibility to our patients to try to make procedures ... patients back annually, which we feel is our responsibility any time we do valve replacement or repair ...

  9. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... patients in the sixth and seventh decades of life. Again, some areas of the valve appear normal ... have been proven to slow that disease path life. Again, it's a progressive disease from sclerosis, or ...

  10. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... to prevent such a problem. Is there a higher risk in someone with a biological valve for ... there but in my experience they're no higher than in someone who's had a full sternotomy. ...

  11. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... North Carolina. My name is John Streitman and I'm a cardiothoracic surgeon here at the Heart ... the corrective surgery of aortic valve replacement. If I have aortic stenosis, are there any activities that ...

  12. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... back in World War II to look for things in the water. Basically, you use sound waves ... valve replacements a year. So one of the things I 10 would counsel anybody is before they ...

  13. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... Dr. Jim Winkley, who's a cardiac anesthesiologist that works here with us. Before we begin, viewers need ... the valve itself has narrowed, that puts more work on the heart when a patient's at rest. ...

  14. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... for patients who would not tolerate well a traditional open operation or a less invasive operation, as ... physical reserve. So Barbara Bush recently had a traditional aortic valve replacement surgery. What makes a patient ...

  15. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... or the devices used in this continuing medical educational activity. Thanks, John, we want to remind the ... a rare problem where the patient's own immune system will attack cardiac valve structures, causing them to ...

  16. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... valve, it's just 1 sort of a normal aging process that we see in a certain segment ... this country is primarily a disease of the aging population. And, of course, we are a country ...

  17. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... at the body's surface area. We, in the operating room, have a set of sizers which allow ... proves a nice replacement. However, that's sort of operating on two valves to fix one valvular problem. ...

  18. CONGENITAL QUADRICUSPID AORTIC-VALVE

    NARCIS (Netherlands)

    BROUWER, MHJ; DEGRAAF, JJ; EBELS, T

    1993-01-01

    Two patients with a quadricuspid aortic valve are described, one of them with concomitant juxtaposed coronary orifices facing the right hand facing sinus. The etiology and incidence of this congenital anomaly will be discussed.

  19. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... a patient less post-operative pain, blood loss, lung dysfunction. Certainly we can get these patients up ... thorocotomy is an incision we generally use for lung operations and for some valve operations in which ...

  20. The spin-valve transistor

    NARCIS (Netherlands)

    Monsma, Douwe Johannes

    1998-01-01

    High density magnetic recording, magnetic random access memories, displacement and current detection, contactless switching and electronic compass applications all require magnetic field sensors with unprecedented sensitivity. The spin-valve effect (giant magnetoresistance) found in 1988 in magnetic

  1. Residential Forced Air System Cabinet Leakage and Blower Performance

    OpenAIRE

    Walker, Iain S.

    2010-01-01

    This project evaluated the air leakage and electric power consumption of Residential HVAC components, with a particular focus on air leakage of furnace cabinets. Laboratory testing of HVAC components indicated that air leakage can be significant and highly variable from unit to unit ? indicating the need for a standard test method and specifying maximum allowable air leakage in California State energy codes. To further this effort, this project provided technical assistance for the developm...

  2. 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

    even 10(exp 9) cycles is well above anything demonstrated, this lower value was selected as the design point for the present work. The valve seal must remain leak-tight throughout operation, and the body must maintain a low internal leakage at relatively high operating temperatures. The full set of design requirements used for this program are summarized in Table 1. In this work, we describe two pulsed gas valves that have been fabricated to have long lifetime and demonstrate the characteristics listed above. The first is a miniaturized, conventional electromagnet-based valve while the second is a piezoelectric-based valve design. The conventional valve, shown in Fig. 1, is opened by use of a solenoid electromagnetic actuator. When current is applied to the solenoid coil, magnetic forces pull the plunger away from the valve seat, allowing fluid to flow through the valve. Removal of electrical current permits the spring and fluid pressure to seat the plunger, halting the flow of fluid. The valve body is fabricated from 304L corrosion resistant steel (CRES) and while the parts that form the magnetic circuit are fabricated from 430 CRES. This material does not have optimum magnetic properties, but its corrosion resistance permits incorporation into a design without requiring an additional plating process. A viton O-ring compound (Parker V0884-75), selected for its mechanical strength at elevated temperatures, was used for the valve seat seal. The design was based solely on the use of analytical sizing calculations, as opposed to a more rigorous finite element analysis. While this valve is small and relatively lightweight, it does not represent a design that is optimized for mass and/or a given volume envelope. The piezoelectric valve is a "puller" valve design. Applying a voltage to the piezo crystal causes it to elongate and pull a pintle off the seat, opening the valve. The valve seal consists of the pintle with an external, spherically-formed tip fabricated from

  3. Magnetic shaft seals prevent hazardous leakage from wastewater agitators

    International Nuclear Information System (INIS)

    The US Department of Energy's laboratory in Miamisburg, OH, operated by Monsanto Research Corporation, processes approximately 45,000 gallons per week of low-level radioactive wastewater to meet Federal Environmental Protection Agency quality standards. Preventing the spread of radioactive contamination throughout the operating area demands effective sealing of all process piping, valves, pumps, and agitators. Rotating shafts of pumps and agitators installed a the start of operations in 1947 were sealed by stuffing glands with graphite impregnated asbestos packing. These pumps proved to be unsatisfactory. In the mid-1970's, new process pumps with mechanical seals and some with magnetic drives were installed. Later, in January 1979, new agitator shaft drives with double tandem, spring-loaded mechanical seals were installed, maintenance of these pumps was costly. The agitator drive shafts were redesigned to accommodate magnetic seals of the type successfully used in blowers and vacuum/pressure pumps in other plant locations. One inherent advantage of the magnetic seal is that it operates with a face loading as much as 50% less than a conventional spring-loaded mechanical seal. The lower loading by a predetermined uniform magnetic force contributes to long face life. Other advantages include compactness, ease of assembly with only a few parts, and insensitivity to vibration. The magnetic shaft seals installed on the agitator shafts in February 1983 are still in service without any leakage or need for maintenance. Based on current operating data and a projected five-year meantime between failures, the estimated cost benefit of the magnetic seals over spring-loaded mechanical seals over spring-loaded mechanical seals will be $640 vs $2400 respectively per seal, with 60% less downtime for maintenance

  4. Junction leakage measurements with micro four-point probes

    DEFF Research Database (Denmark)

    Lin, Rong; Petersen, Dirch Hjorth; Wang, Fei;

    2012-01-01

    We present a new, preparation-free method for measuring the leakage current density on ultra-shallow junctions. The junction leakage is found by making a series of four-point sheet resistance measurements on blanket wafers with variable electrode spacings. The leakage current density is calculated...

  5. Leakage Inductance Calculation for Planar Transformers with a Magnetic Shunt

    DEFF Research Database (Denmark)

    Jun, Zhang; Ouyang, Ziwei; Duffy, M. C.;

    2013-01-01

    The magnetic shunt is generally inserted in a planar transformer to increase the leakage inductance which can be utilized as the series inductor in resonant circuits such as the LLC resonant converter. This paper presents a calculation methodology for the leakage inductance of the transformer...... and the experimental results have proven the validity of the proposed calculation method for leakage inductance....

  6. Leakage Inductance Calculation for Planar Transformers with a Magnetic Shunt

    DEFF Research Database (Denmark)

    Zhang, Jun; Ouyang, Ziwei; Duffy, Maeve C.;

    2014-01-01

    The magnetic shunt is generally inserted in a planar transformer to increase the leakage inductance which can be utilized as the series inductor in resonant circuits such as the LLC resonant converter. This paper presents a calculation methodology for the leakage inductance of the transformer...... and the experimental results have proven the validity of the proposed calculation method for leakage inductance....

  7. 49 CFR 192.706 - Transmission lines: Leakage surveys.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Transmission lines: Leakage surveys. 192.706... Transmission lines: Leakage surveys. Leakage surveys of a transmission line must be conducted at intervals not exceeding 15 months, but at least once each calendar year. However, in the case of a transmission line...

  8. Techniques for Leakage Power Reduction in Nanoscale Circuits: A Survey

    DEFF Research Database (Denmark)

    Liu, Wei

    This report surveys progress in the field of designing low power especially low leakage CMOS circuits in deep submicron era. The leakage mechanism and various recently proposed run time leakage reduction techniques are presented. Two designs from Cadence and Sony respectively, which can represent...

  9. Enriched MU-Calculi Module Checking

    CERN Document Server

    Ferrante, Alessandro; Parente, Mimmo

    2008-01-01

    The model checking problem for open systems has been intensively studied in the literature, for both finite-state (module checking) and infinite-state (pushdown module checking) systems, with respect to Ctl and Ctl*. In this paper, we further investigate this problem with respect to the Mu-calculus enriched with nominals and graded modalities (hybrid graded Mu-calculus), in both the finite-state and infinite-state settings. Using an automata-theoretic approach, we show that hybrid graded Mu-calculus module checking is solvable in exponential time, while hybrid graded Mu-calculus pushdown module checking is solvable in double-exponential time. These results are also tight since they match the known lower bounds for Ctl. We also investigate the module checking problem with respect to the hybrid graded Mu-calculus enriched with inverse programs (Fully enriched Mu-calculus): by showing a reduction from the domino problem, we show its undecidability. We conclude with a short overview of the model checking problem ...

  10. Methane leakage in natural gas operations

    International Nuclear Information System (INIS)

    The world gas industry is efficient in conservation of natural gas within its systems. As the influence of methane as an infra-red absorbent gas has been more widely recognized, the considerations of methane's greenhouse effect has become vitally important to gas companies around the world. The industry is universally environmentally conscious. natural gas transmission and distribution companies want to maintain their image as suppliers of clean fuel. Further reductions in methane leakage --- particularly in older distribution systems --- can, should and will be pursued. Unfortunately, there has been little exchange of views on methane leakages between commentators on environmental matters and gas companies and organizations. There is absolutely no need for the industry to avoid the issue of greenhouse gases. Without industry involvement, the environmental debate concerning fossil fuels could lead to selective interpretation of scientific views and available evidence. Companies and authorities would be presented with confusing, contradictory evidence on which to base policy approaches and regulations

  11. Leakage Resilient Secure Two-Party Computation

    DEFF Research Database (Denmark)

    Damgård, Ivan Bjerre; Hazay, Carmit; Patra, Arpita

    2012-01-01

    and returns its result. Almost independently of secure computation, the area of {\\em leakage resilient cryptography} has recently been evolving intensively, studying the question of designing cryptographic primitives that remain secure even when some information about the secret key is leaked. In this paper...... Definitions.} We formalize the notion of secure two-party computation in the presence of leakage and introduce security definitions in the {\\em ideal/real framework}. Our formalization induces two types of adversarial attacks. We further study the feasibility of our definitions in the computational setting...... and explore some of the conditions under which these definitions are met. \\item {\\em Composition Theorems.} We provide compositions theorems for our new modelings. Our results provide compositions theorems for the case where the inputs of the parties are sampled from a min-entropy source distribution. \\item...

  12. 3DHZETRN: Neutron leakage in finite objects

    Science.gov (United States)

    Wilson, John W.; Slaba, Tony C.; Badavi, Francis F.; Reddell, Brandon D.; Bahadori, Amir A.

    2015-11-01

    The 3DHZETRN formalism was recently developed as an extension to HZETRN with an emphasis on 3D corrections for neutrons and light ions. Comparisons to Monte Carlo (MC) simulations were used to verify the 3DHZETRN methodology in slab and spherical geometry, and it was shown that 3DHZETRN agrees with MC codes to the degree that various MC codes agree among themselves. One limitation of such comparisons is that all of the codes (3DHZETRN and three MC codes) utilize different nuclear models/databases; additionally, using a common nuclear model is impractical due to the complexity of the software. It is therefore difficult to ascertain if observed discrepancies are caused by transport code approximations or nuclear model differences. In particular, an important simplification in the 3DHZETRN formalism assumes that neutron production cross sections can be represented as the sum of forward and isotropic components, where the forward component is subsequently solved within the straight-ahead approximation. In the present report, previous transport model results in specific geometries are combined with additional results in related geometries to study neutron leakage using the Webber 1956 solar particle event as a source boundary condition. A ratio is defined to quantify the fractional neutron leakage at a point in a finite object relative to a semi-infinite slab geometry. Using the leakage ratio removes some of the dependence on the magnitude of the neutron production and clarifies the effects of angular scattering and absorption with regard to differences between the models. Discussion is given regarding observed differences between the MC codes and conclusions drawn about the need for further code development. Although the current version of 3DHZETRN is reasonably accurate compared to MC simulations, this study shows that improved leakage estimates can be obtained by replacing the isotropic/straight-ahead approximation with more detailed descriptions.

  13. MODELING, VALIDATION AND OPTIMAL DESIGN OF THE CLAMPING FORCE CONTROL VALVE USED IN CONTINUOUSLY VARIABLE TRANSMISSION

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yunshan; LIU Jin'gang; CAI Yuanchun; ZOU Naiwei

    2008-01-01

    Associated dynamic performance of the clamping force control valve used in continuously variable transmission (CVT) is optimized. Firstly, the structure and working principle of the valve are analyzed, and then a dynamic model is set up by means of mechanism analysis. For the purpose of checking the validity of the modeling method, a prototype workpiece of the valve is manufactured for comparison test, and its simulation result follows the experimental result quite well. An associated performance index is founded considering the response time, overshoot and saving energy, and five structural parameters are selected to adjust for deriving the optimal associated performance index. The optimization problem is solved by the genetic algorithm (GA) with necessary constraints. Finally, the properties of the optimized valve are compared with those of the prototype workpiece, and the results prove that the dynamic performance indexes of the optimized valve are much better than those of the prototype workpiece.Key words: Dynamic modeling Optimal design Genetic algorithm Clamping force control valve Continuously variable transmission (CVT)

  14. Characterization of Prototype Superfluid Helium Safety Relief Valves for the LHC Magnets

    CERN Document Server

    Dufay, L; Van Weelderen, R

    1999-01-01

    The Large Hadron Collider (LHC) at CERN will use high field superconducting magnets operating in pressurized superfluid helium (He II) at 1.9 K. Cold safety valves, with their inlet in direct contact with the He II bath, will be required to protect the cold masses in case of a magnet resistive transition. In addition to the safety function, the valves must limit their conduction heat load to the He II to below 0.3 W and limit their mass leakage when closed to below 0.01 g/s at 1.9 K with 100 mbar differential pressure. The valves must also have a high tolerance to contaminating particles in the liquid helium. The compliance with the specified performance is of crucial importance for the LHC cryogenic operation. An extensive test program is therefore being carried out on prototype industrial valves produced by four different manufacturers. The behavior of these valves has been investigated at room temperature and at 77 K. Precise heat load and mass leak measurements have been performed on a dedicated test faci...

  15. Mitigation of Shear-Induced Blood Damage of Mechanical Bileaflet Heart Valves using Embedded Vortex Generators

    Science.gov (United States)

    Hidalgo, Pablo; Arjunon, Sivakkumar; Saikrishnan, Neelakantan; Yoganathan, Ajit; Glezer, Ari

    2012-11-01

    The strong transitory shear stress generated during the time-periodic closing of the mechanical prosthetic bileaflet aortic heart valve, is considered to be one of the main factors responsible for complications, associated with thrombosis and thromboembolism. These flow transients are investigated using phase and time-averaged PIV in a low-volume (about 150 ml) test setup that simulates the pulsatile physiological conditions associated with a 23 mm St. Jude Medical valve. The PIV measurements are accompanied by continuous monitoring of the ventricular and aortic pressures and valve flow rate. Following the valve closure, the leakage flow between the valve leaflets is caused by the pressure buildup across the leaflets, leading to the formation of a regurgitation jet starting from the BMHV B-datum line. As in a typical starting jet, a counter-rotating vortex pair is formed along each leaflet edge and the vorticity sheet is associated with high shear stress that may be result in blood platelet activation. The present investigation demonstrates that the placement of arrays of mm-scale vortex generators near the edges of the leaflets diffuses the vortex sheet and suppresses the formation of these vortices, weakening the local velocity gradients and small-scale vortical structures. Supported by NIH and NSF.

  16. In vitro hydrodynamic, transient, and overtime performance of a miniaturized valve for hydrocephalus.

    Science.gov (United States)

    Schwerdt, Helen N; Amjad, Usamma; Appel, Jennie; Elhadi, Ali M; Lei, Ting; Preul, Mark C; Bristol, Ruth E; Chae, Junseok

    2015-03-01

    Reliable cerebrospinal fluid (CSF) draining methods are needed to treat hydrocephalus, a chronic debilitating brain disorder. Current shunt implant treatments are characterized by high failure rates that are to some extent attributed to their length and multiple components. The designed valve, made of hydrogel, steers away from such protracted schemes and intends to provide a direct substitute for faulty arachnoid granulations, the brain's natural CSF draining valves, and restore CSF draining operations within the cranium. The valve relies on innate hydrogel swelling phenomena to strengthen reverse flow sealing at idle and negative pressures thereby alleviating common valve failure mechanisms. In vitro measurements display operation in range of natural CSF draining (cracking pressure, PT ~ 1-110 mmH2O and outflow hydraulic resistance, Rh ~ 24-152 mmH2O/mL/min), with negligible reverse flow leakage (flow, QO > -10 µL/min). Hydrodynamic measurements and over-time tests under physically relevant conditions further demonstrate the valve's operationally-reproducible properties and strengthen its validity for use as a chronic implant.

  17. Small sodium valve design and operating experience

    International Nuclear Information System (INIS)

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

  18. Development of an effective valve packing program

    Energy Technology Data Exchange (ETDEWEB)

    Hart, K.A.

    1996-12-01

    Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

  19. 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)

    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 2009th 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. These

  20. Recent NRC research activities addressing valve and pump issues

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, D.L.

    1996-12-01

    The mission of the U.S. Nuclear Regulatory Commission (NRC) is to ensure the safe design, construction, and operation of commercial nuclear power plants and other facilities in the U.S.A. One of the main roles that the Office of Nuclear Regulatory Research (RES) plays in achieving the NRC mission is to plan, recommend, and implement research programs that address safety and technical issues deemed important by the NRC. The results of the research activities provide the bases for developing NRC positions or decisions on these issues. Also, RES performs confirmatory research for developing the basis to evaluate industry responses and positions on various regulatory requirements. This presentation summarizes some recent RES supported research activities that have addressed safety and technical issues related to valves and pumps. These activities include the efforts on determining valve and motor-operator responses under dynamic loads and pressure locking events, evaluation of monitoring equipment, and methods for detecting and trending aging of check valves and pumps. The role that RES is expected to play in future years to fulfill the NRC mission is also discussed.

  1. Alopecia associated with unexpected leakage from electron cone

    International Nuclear Information System (INIS)

    Excessive irradiation due to unexpected leakage was found on a patient receiving electron beam therapy. The cause of this leakage was analyzed and the amount of leakage was measured for different electron beam energies. The highest leakage occurred with a 6 x 6 cm cone using a 12 MeV electron beam. The leakage dose measured along the side of the cone could be as great as 40%. Until the cones are modified or redesigned, it is advised that all patient setups be carefully reviewed to assure that no significant patient areas are in the side scatter region

  2. TRACKING DOWN DATA LEAKAGE BY USING ENCRYPTED FAKE OBJECTS

    OpenAIRE

    Anugu Rahul Reddy; BalaKrishna Bangaru

    2014-01-01

    This paper contains concept of data leakage, its causes of leakage and different techniques to protect and detect the data leakage. The value of the data is incredible, so it should not be leaked or altered. In the field of IT, huge database is being used. This database is shared with multiple people at a time. But during this sharing of the data, there are huge chances of data vulnerability, leakage or alteration. So, to prevent these problems, a data leakage detection system has...

  3. Alopecia associated with unexpected leakage from electron cone

    Energy Technology Data Exchange (ETDEWEB)

    Wen, B.C.; Pennington, E.C.; Hussey, D.H.; Jani, S.K.

    1989-06-01

    Excessive irradiation due to unexpected leakage was found on a patient receiving electron beam therapy. The cause of this leakage was analyzed and the amount of leakage was measured for different electron beam energies. The highest leakage occurred with a 6 x 6 cm cone using a 12 MeV electron beam. The leakage dose measured along the side of the cone could be as great as 40%. Until the cones are modified or redesigned, it is advised that all patient setups be carefully reviewed to assure that no significant patient areas are in the side scatter region.

  4. Computational Fact Checking from Knowledge Networks.

    Directory of Open Access Journals (Sweden)

    Giovanni Luca Ciampaglia

    Full Text Available Traditional fact checking by expert journalists cannot keep up with the enormous volume of information that is now generated online. Computational fact checking may significantly enhance our ability to evaluate the veracity of dubious information. Here we show that the complexities of human fact checking can be approximated quite well by finding the shortest path between concept nodes under properly defined semantic proximity metrics on knowledge graphs. Framed as a network problem this approach is feasible with efficient computational techniques. We evaluate this approach by examining tens of thousands of claims related to history, entertainment, geography, and biographical information using a public knowledge graph extracted from Wikipedia. Statements independently known to be true consistently receive higher support via our method than do false ones. These findings represent a significant step toward scalable computational fact-checking methods that may one day mitigate the spread of harmful misinformation.

  5. Computational Fact Checking from Knowledge Networks.

    Science.gov (United States)

    Ciampaglia, Giovanni Luca; Shiralkar, Prashant; Rocha, Luis M; Bollen, Johan; Menczer, Filippo; Flammini, Alessandro

    2015-01-01

    Traditional fact checking by expert journalists cannot keep up with the enormous volume of information that is now generated online. Computational fact checking may significantly enhance our ability to evaluate the veracity of dubious information. Here we show that the complexities of human fact checking can be approximated quite well by finding the shortest path between concept nodes under properly defined semantic proximity metrics on knowledge graphs. Framed as a network problem this approach is feasible with efficient computational techniques. We evaluate this approach by examining tens of thousands of claims related to history, entertainment, geography, and biographical information using a public knowledge graph extracted from Wikipedia. Statements independently known to be true consistently receive higher support via our method than do false ones. These findings represent a significant step toward scalable computational fact-checking methods that may one day mitigate the spread of harmful misinformation. PMID:26083336

  6. Consistency Checking of Web Service Contracts

    DEFF Research Database (Denmark)

    Cambronero, M. Emilia; Okika, Joseph C.; Ravn, Anders Peter

    2008-01-01

    Behavioural properties are analyzed for web service contracts formulated in Business Process Execution Language (BPEL) and Choreography Description Language (CDL). The key result reported is an automated technique to check consistency between protocol aspects of the contracts. The contracts...

  7. Computational fact checking from knowledge networks

    CERN Document Server

    Ciampaglia, Giovanni Luca; Rocha, Luis M; Bollen, Johan; Menczer, Filippo; Flammini, Alessandro

    2015-01-01

    Traditional fact checking by expert journalists cannot keep up with the enormous volume of information that is now generated online. Computational fact checking may significantly enhance our ability to evaluate the veracity of dubious information. Here we show that the complexities of human fact checking can be approximated quite well by finding the shortest path between concept nodes under properly defined semantic proximity metrics on knowledge graphs. Framed as a network problem this approach is feasible with efficient computational techniques. We evaluate this approach by examining tens of thousands of claims related to history, entertainment, geography, and biographical information using a public knowledge graph extracted from Wikipedia. Statements independently known to be true consistently receive higher support via our method than do false ones. These findings represent a significant step toward scalable computational fact-checking methods that may one day mitigate the spread of harmful misinformation...

  8. Computational Fact Checking from Knowledge Networks

    Science.gov (United States)

    Ciampaglia, Giovanni Luca; Shiralkar, Prashant; Rocha, Luis M.; Bollen, Johan; Menczer, Filippo; Flammini, Alessandro

    2015-01-01

    Traditional fact checking by expert journalists cannot keep up with the enormous volume of information that is now generated online. Computational fact checking may significantly enhance our ability to evaluate the veracity of dubious information. Here we show that the complexities of human fact checking can be approximated quite well by finding the shortest path between concept nodes under properly defined semantic proximity metrics on knowledge graphs. Framed as a network problem this approach is feasible with efficient computational techniques. We evaluate this approach by examining tens of thousands of claims related to history, entertainment, geography, and biographical information using a public knowledge graph extracted from Wikipedia. Statements independently known to be true consistently receive higher support via our method than do false ones. These findings represent a significant step toward scalable computational fact-checking methods that may one day mitigate the spread of harmful misinformation. PMID:26083336

  9. CMM Interim Check Design of Experiments (U)

    Energy Technology Data Exchange (ETDEWEB)

    Montano, Joshua Daniel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-07-29

    Coordinate Measuring Machines (CMM) are widely used in industry, throughout the Nuclear Weapons Complex and at Los Alamos National Laboratory (LANL) to verify part conformance to design definition. Calibration cycles for CMMs at LANL are predominantly one year in length and include a weekly interim check to reduce risk. The CMM interim check makes use of Renishaw’s Machine Checking Gauge which is an off-the-shelf product simulates a large sphere within a CMM’s measurement volume and allows for error estimation. As verification on the interim check process a design of experiments investigation was proposed to test a couple of key factors (location and inspector). The results from the two-factor factorial experiment proved that location influenced results more than the inspector or interaction.

  10. For Better Skin Cancer Checks, Partner Up

    Science.gov (United States)

    ... medlineplus.gov/news/fullstory_159632.html For Better Skin Cancer Checks, Partner Up Melanoma survivors benefited when they ... out: Getting a partner trained to spot potential skin cancers can be a lifesaver for melanoma survivors, a ...

  11. 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.

  12. Generic Architecture for Mobile Check System

    OpenAIRE

    KARIMA MAAZOUZ; HABIB.BENLAHMER; NACEUR.ACHTAICH

    2013-01-01

    the explosion of the market of Smartphone has rapidly changed the way of m-commerce transactions, especially the m-payment systems which are knowing a wide acceptance due to their diversity and the new mobile technologies. In this work we have introduced the system m-check as a mobile payment system, we have presented a generic architecture of the system and the different protocols for the implementation of the system m-check

  13. Generic Architecture for Mobile Check System

    Directory of Open Access Journals (Sweden)

    KARIMA MAAZOUZ

    2013-11-01

    Full Text Available the explosion of the market of Smartphone has rapidly changed the way of m-commerce transactions, especially the m-payment systems which are knowing a wide acceptance due to their diversity and the new mobile technologies. In this work we have introduced the system m-check as a mobile payment system, we have presented a generic architecture of the system and the different protocols for the implementation of the system m-check

  14. Engineering Abstractions in Model Checking and Testing

    OpenAIRE

    Achenbach, Michael; Ostermann, Klaus

    2009-01-01

    Abstractions are used in model checking to tackle problems like state space explosion or modeling of IO. The application of these abstractions in real software development processes, however, lacks engineering support. This is one reason why model checking is not widely used in practice yet and testing is still state of the art in falsification. We show how user-defined abstractions can be integrated into a Java PathFinder setting with tools like AspectJ or Javassist and discuss implicati...

  15. Online treatment compliance checking for clinical pathways.

    Science.gov (United States)

    Huang, Zhengxing; Bao, Yurong; Dong, Wei; Lu, Xudong; Duan, Huilong

    2014-10-01

    Compliance checking for clinical pathways (CPs) is getting increasing attention in health-care organizations due to stricter requirements for cost control and treatment excellence. Many compliance measures have been proposed for treatment behavior inspection in CPs. However, most of them look at aggregated data seen from an external perspective, e.g. length of stay, cost, infection rate, etc., which may provide only a posterior impression of the overall conformance with the established CPs such that in-depth and in near real time checking on the compliance of the essential/critical treatment behaviors of CPs is limited. To provide clinicians real time insights into violations of the established CP specification and support online compliance checking, this article presents a semantic rule-based CP compliance checking system. In detail, we construct a CP ontology (CPO) model to provide a formal grounding of CP compliance checking. Using the proposed CPO, domain treatment constraints are modeled into Semantic Web Rule Language (SWRL) rules to specify the underlying treatment behaviors and their quantified temporal structure in a CP. The established SWRL rules are integrated with the CP workflow such that a series of applicable compliance checking and evaluation can be reminded and recommended during the pathway execution. The proposed approach can, therefore, provides a comprehensive compliance checking service as a paralleling activity to the patient treatment journey of a CP rather than an afterthought. The proposed approach is illustrated with a case study on the unstable angina clinical pathway implemented in the Cardiology Department of a Chinese hospital. The results demonstrate that the approach, as a feasible solution to provide near real time conformance checking of CPs, not only enables clinicians to uncover non-compliant treatment behaviors, but also empowers clinicians with the capability to make informed decisions when dealing with treatment compliance

  16. Check Point认证简介

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Check Point软件技术有限公司是因特网安全领域的全球著名企业,占有全球65%VPN/防火墙市场份额(IDC 2002),财富前100强中有97家公司采用Check Point的安全产品。

  17. Online treatment compliance checking for clinical pathways.

    Science.gov (United States)

    Huang, Zhengxing; Bao, Yurong; Dong, Wei; Lu, Xudong; Duan, Huilong

    2014-10-01

    Compliance checking for clinical pathways (CPs) is getting increasing attention in health-care organizations due to stricter requirements for cost control and treatment excellence. Many compliance measures have been proposed for treatment behavior inspection in CPs. However, most of them look at aggregated data seen from an external perspective, e.g. length of stay, cost, infection rate, etc., which may provide only a posterior impression of the overall conformance with the established CPs such that in-depth and in near real time checking on the compliance of the essential/critical treatment behaviors of CPs is limited. To provide clinicians real time insights into violations of the established CP specification and support online compliance checking, this article presents a semantic rule-based CP compliance checking system. In detail, we construct a CP ontology (CPO) model to provide a formal grounding of CP compliance checking. Using the proposed CPO, domain treatment constraints are modeled into Semantic Web Rule Language (SWRL) rules to specify the underlying treatment behaviors and their quantified temporal structure in a CP. The established SWRL rules are integrated with the CP workflow such that a series of applicable compliance checking and evaluation can be reminded and recommended during the pathway execution. The proposed approach can, therefore, provides a comprehensive compliance checking service as a paralleling activity to the patient treatment journey of a CP rather than an afterthought. The proposed approach is illustrated with a case study on the unstable angina clinical pathway implemented in the Cardiology Department of a Chinese hospital. The results demonstrate that the approach, as a feasible solution to provide near real time conformance checking of CPs, not only enables clinicians to uncover non-compliant treatment behaviors, but also empowers clinicians with the capability to make informed decisions when dealing with treatment compliance

  18. Project Boundary Setting and Leakage Treatment in CDM Project

    Institute of Scientific and Technical Information of China (English)

    ZOU Chen; WANG Shujuan; DUAN Maosheng; CHEN Changhe

    2005-01-01

    Project boundary setting and leakage treatment are two important issues to be considered when a clean development mechanism (CDM) project is being designed. There are still many uncertainties concerning these two issues. This paper reviews the concepts of project boundary setting and leakage in CDM projects, cites the types and sources of leakage, discusses the principles for determining leakage, and gives some proposed methods for dealing with leakage. A case study, using several steps to solve the boundary and leakage problems,shows how the analyzed principles and treatments can be implemented in a real project. Based on the result of the case study, the methods discussed are shown to be appropriate for settling leakage issues.

  19. FELERION: a new approach for leakage power reduction

    Science.gov (United States)

    R, Anjana; Somkuwar, Ajay

    2014-12-01

    The circuit proposed in this paper simultaneously reduces the sub threshold leakage power and saves the state of art aspect of the logic circuits. Sleep transistors and PMOS-only logic are used to further reduce the leakage power. Sleep transistors are used as the keepers to reduce the sub threshold leakage current providing the low resistance path to the output. PMOS-only logic is used between the pull up and pull down devices to mitigate the leakage power further. Our proposed fast efficient leakage reduction circuit not only reduces the leakage current but also reduces the power dissipation. Power and delay are analyzed at the 32 nm BSIM4 model for a chain of four inverters, NAND, NOR and ISCAS-85 c17 benchmark circuits using DSCH3 and the Microwind tool. The simulation results reveal that our proposed approach mitigates leakage power by 90%-94% as compared to the conventional approach.

  20. THE FINITE ELEMENT MODEL OF LEAKAGE PHENOMENA UNDER THE SOIL DAMS

    Directory of Open Access Journals (Sweden)

    Mahmud GÜNGÖR

    1995-01-01

    Full Text Available Dams can store billions and billions m3 of water in their reservoirs. So leakage phenomenon which threats the stabilitiy of building sould be well examined. In this paper, flow that occurs in the dam's body and at the bottom of dam as a result of leaking water from the earth filled dam's reservoir is examined numericaly. For this purpose, the finite elements model of the phenomenon has been set up with the help of a computer program, the mathematical equation for whole area was calculated, velocity and potential distribution of the flow in the dam's body and at the bottom were obtained. The values of pore water and leak pressure which were previously calculated by graphical method and hand drown flow net can be obtained more precisely by the use of velocity and potential valves obtained by finite element method which is used in this study.

  1. Aggressive chemical decontamination tests on small valves from the Garigliano BWR

    International Nuclear Information System (INIS)

    In order to check the effectiveness of direct chemical decontamination on small and complex components, usually considered for storage without decontamination because of the small amount, some tests were performed on the DECO experimental loop. Four small stainless steel valves from the primary system of the Garigliano BWR were decontaminated using mainly aggressive chemicals such as HC1, HF, HNO3 and their mixtures. On two valves, before the treatment with aggressive chemicals, a step with soft chemical (oxalic and citric acid mixture) was performed in order to see whether a softening action enhances the following aggressive decontamination. Moreover, in order to increase as much as possible the decontamination effectiveness, a decontamination process using ultrasounds jointly with aggressive chemicals was investigated. After an intensive laboratory testing programme, two smaller stainless steel valves from the primary system of the Garigliano BWR were decontaminated using ultrasounds in aggressive chemical solutions

  2. Analysis of Complex Valve and Feed Systems

    Science.gov (United States)

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

    2007-01-01

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

  3. Large Scale Magnetostrictive Valve Actuator

    Science.gov (United States)

    Richard, James A.; Holleman, Elizabeth; Eddleman, David

    2008-01-01

    Marshall Space Flight Center's Valves, Actuators and Ducts Design and Development Branch developed a large scale magnetostrictive valve actuator. The potential advantages of this technology are faster, more efficient valve actuators that consume less power and provide precise position control and deliver higher flow rates than conventional solenoid valves. Magnetostrictive materials change dimensions when a magnetic field is applied; this property is referred to as magnetostriction. Magnetostriction is caused by the alignment of the magnetic domains in the material s crystalline structure and the applied magnetic field lines. Typically, the material changes shape by elongating in the axial direction and constricting in the radial direction, resulting in no net change in volume. All hardware and testing is complete. This paper will discuss: the potential applications of the technology; overview of the as built actuator design; discuss problems that were uncovered during the development testing; review test data and evaluate weaknesses of the design; and discuss areas for improvement for future work. This actuator holds promises of a low power, high load, proportionally controlled actuator for valves requiring 440 to 1500 newtons load.

  4. Semantic rule-checking for regulation compliance checking: an overview of strategies and approaches

    OpenAIRE

    Pauwels, Pieter; Zhang, Sijie

    2015-01-01

    As more and more architectural design and construction data is represented in the Resource Description Framework (RDF) data model, it makes sense to take advantage of the underlying logical basis of RDF and realise a semantic rule-checking process as it is currently not available in architectural design and construction industry. Such a semantic rule-checking process would be of considerable value to regulation compliance checking procedures, because the additional logical basis would (1) all...

  5. MPST Software: grl_pef_check

    Science.gov (United States)

    Call, Jared A.; Kwok, John H.; Fisher, Forest W.

    2013-01-01

    This innovation is a tool used to verify and validate spacecraft sequences at the predicted events file (PEF) level for the GRAIL (Gravity Recovery and Interior Laboratory, see http://www.nasa. gov/mission_pages/grail/main/index. html) mission as part of the Multi-Mission Planning and Sequencing Team (MPST) operations process to reduce the possibility for errors. This tool is used to catch any sequence related errors or issues immediately after the seqgen modeling to streamline downstream processes. This script verifies and validates the seqgen modeling for the GRAIL MPST process. A PEF is provided as input, and dozens of checks are performed on it to verify and validate the command products including command content, command ordering, flight-rule violations, modeling boundary consistency, resource limits, and ground commanding consistency. By performing as many checks as early in the process as possible, grl_pef_check streamlines the MPST task of generating GRAIL command and modeled products on an aggressive schedule. By enumerating each check being performed, and clearly stating the criteria and assumptions made at each step, grl_pef_check can be used as a manual checklist as well as an automated tool. This helper script was written with a focus on enabling the user with the information they need in order to evaluate a sequence quickly and efficiently, while still keeping them informed and active in the overall sequencing process. grl_pef_check verifies and validates the modeling and sequence content prior to investing any more effort into the build. There are dozens of various items in the modeling run that need to be checked, which is a time-consuming and errorprone task. Currently, no software exists that provides this functionality. Compared to a manual process, this script reduces human error and saves considerable man-hours by automating and streamlining the mission planning and sequencing task for the GRAIL mission.

  6. SLM Produced Hermetically Sealed Isolation Valve

    Science.gov (United States)

    Richard, James A.

    2014-01-01

    Marshall Space Flight Center (MSFC) has developed a valve concept to replace traditional pyrotechnic driven isolation valves. This paper will describe the valve design and development process. The valve design uses a stem/wedge to support a disk inside the valve. That disk hermetically seals the pressurized fluids. A release mechanism holds the stem/wedge and a large spring in place. When required to open, a solenoid is energized and pulls the release mechanism allowing the spring to pull the stem/wedge away from the disk. Now the disk is unsupported and the pressure ruptures the disk allowing flow to the outlet of the valve. This paper will provide details of this design, describe the development testing, and show the results from the valve level tests performed. Also, a trade study is presented to show the advantages of this design to a conventional pyrotechnic based valve.

  7. Percutaneous heart valves; past, present and future.

    Science.gov (United States)

    Rozeik, M M; Wheatley, D J; Gourlay, T

    2014-09-01

    Percutaneous heart valves provide a promising future for patients refused surgery on the grounds of significant technical challenges or high risk for complications. Since the first human intervention more than 10 years ago, over 50 different types of valves have been developed. The CoreValve and Edwards SAPIEN valves have both experienced clinical trials and the latter has gained FDA approval for implantation in patients considered inoperable. Current complications, such as major vascular bleeding and stroke, prevent these valves from being commonly deployed in patients considered operable in conventional surgery. This review focuses on the past and present achievements of these valves and highlights the design considerations required to progress development further. It is envisaged that, with continued improvement in valve design and with increased clinical and engineering experience, percutaneous heart valve replacement may one day be a viable option for lower-risk operable patients.

  8. Cryptorchidism in boys with posterior urethral valves.

    Science.gov (United States)

    Krueger, R P; Hardy, B E; Churchill, B M

    1980-07-01

    A review of 207 male children with poterior urethral valves revealed an over-all incidence of cryptorchidism of 12 per cent. This association of cryptorchidism in boys with posterior urethral valves has not been described previously. PMID:6106069

  9. How Is Heart Valve Disease Treated?

    Science.gov (United States)

    ... is called a valve-in-valve procedure. Heart-Healthy Lifestyle Changes to Treat Other Related Heart Conditions To ... your doctor may advise you to make heart-healthy lifestyle changes, such as: Heart-healthy eating Aiming for ...

  10. EVA Suit Microbial Leakage Investigation Project

    Science.gov (United States)

    Falker, Jay; Baker, Christopher; Clayton, Ronald; Rucker, Michelle

    2016-01-01

    The objective of this project is to collect microbial samples from various EVA suits to determine how much microbial contamination is typically released during simulated planetary exploration activities. Data will be released to the planetary protection and science communities, and advanced EVA system designers. In the best case scenario, we will discover that very little microbial contamination leaks from our current or prototype suit designs, in the worst case scenario, we will identify leak paths, learn more about what affects leakage--and we'll have a new, flight-certified swab tool for our EVA toolbox.

  11. Novel Active Combustion Control Valve

    Science.gov (United States)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  12. Bistable diverter valve in microfluidics

    Science.gov (United States)

    Tesař, V.; Bandalusena, H. C. H.

    2011-05-01

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

  13. 49 CFR 179.400-19 - Valves and gages.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Valves and gages. 179.400-19 Section 179.400-19...-19 Valves and gages. (a) Valves. Manually operated shut-off valves and control valves must be... liquid flow rates. All valves must be made from approved materials compatible with the lading and...

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

    Science.gov (United States)

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

    2016-01-01

    The Medtronic ATS Open Pivot mechanical valve has been successfully used in heart valve surgery for more than two decades. We present the case of a patient who, 19 years following a tricuspid valve replacement with an ATS prosthesis as part of a triple valve operation following infective endocarditis, developed severe tricuspid regurgitation due to pannus formation. PMID:27355145

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    a successful valve-in-valve implantation of a CoreValve aortic valve prosthesis through the right subclavian artery in a case of severe aortic regurgitation within a degenerated aortic homograft. The case exemplifies the possibilities of expanding the indications for TAVI, as well as other vascular access...

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  17. Analysis of U.S. residential air leakage database

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Wanyu R.; Price, Phillip N.; Sohn, Michael D.; Gadgil, Ashok J.

    2003-07-01

    The air leakage of a building envelope can be determined from fan pressurization measurements with a blower door. More than 70,000 air leakage measurements have been compiled into a database. In addition to air leakage, the database includes other important characteristics of the dwellings tested, such as floor area, year built, and location. There are also data for some houses on the presence of heating ducts, and floor/basement construction type. The purpose of this work is to identify house characteristics that can be used to predict air leakage. We found that the distribution of leakage normalized with floor area of the house is roughly lognormal. Year built and floor area are the two most significant factors to consider when predicting air leakage: older and smaller houses tend to have higher normalized leakage areas compared to newer and larger ones. Results from multiple linear regression of normalized leakage with respect to these two factors are presented for three types of houses: low-income, energy-efficient, and conventional. We demonstrate a method of using the regression model in conjunction with housing characteristics published by the US Census Bureau to derive a distribution that describes the air leakage of the single-family detached housing stock. Comparison of our estimates with published datasets of air exchange rates suggests that the regression model generates accurate estimates of air leakage distribution.

  18. Pregnancy-induced remodeling of heart valves.

    Science.gov (United States)

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

    2015-11-01

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

  19. Promising results after percutaneous mitral valve repair

    DEFF Research Database (Denmark)

    Ihlemann, Nikolaj; Franzen, Olaf; Jørgensen, Erik;

    2011-01-01

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

  20. Promising results after percutaneous mitral valve repair

    DEFF Research Database (Denmark)

    Ihlemann, Nikolaj; Franzen, Olaf; Jørgensen, Erik;

    2011-01-01

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

  1. Infective endocarditis following percutaneous pulmonary valve replacement

    DEFF Research Database (Denmark)

    Cheung, Gary; Vejlstrup, Niels; Ihlemann, Nikolaj;

    2013-01-01

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

  2. Development of the large main steam safety relief valve

    Energy Technology Data Exchange (ETDEWEB)

    Takeshima, Kikuo [Hitachi Ltd., Tokyo (Japan); Takasaki, Kiyoshi; Hamada, Nobuyoshi

    2000-02-01

    In order to control rise of reactor pressure at formation of over-pressure transition accident in a boiling water (BWR) type nuclear power plant, the numbers of the main steam safety relief valve (MSSRV) installed in a storage vessel increases with out-put in the plant, and for 1.35 MkW class improved BWR (ABWR) 18 sets of MSSRV are installed. And, in an ABWR preparing of construction at Ohma-cho, Aomori prefecture by the Electric Power Development Co., Ltd., uranium-plutonium mixed oxides (MOX) fuel is planned to load, to tend to further increase required numbers of MSSRV. In order to control arrangement in a storage vessel and increase of conservative inspection work together with increase the required numbers of MSSRV, it was planned to develop a large volume of MSSRV (16% increase in volume on comparison with that of conventional one), to confirm its function and feature by its testing and to apply to an actual machine. Here was introduced on its developmental contents and testing results. As a result, it could be estimated that required numbers of MSSRV would be sixteen, and was confirmed that features such as correlation on flowing-out pressure between nitrogen and steam, durability, work stability, valve seat leakage resistance, and so forth were similar to those of present MSSRV. (G.K.)

  3. Vortex Flipping in Superconductor-Ferromagnet Spin Valve Structures

    Science.gov (United States)

    Patino, Edgar J.; Aprili, Marco; Blamire, Mark; Maeno, Yoshiteru

    2014-03-01

    We report in plane magnetization measurements on Ni/Nb/Ni/CoO and Co/Nb/Co/CoO spin valve structures with one of the ferromagnetic layers pinned by an antiferromagnetic layer. In samples with Ni, below the superconducting transition Tc, our results show strong evidence of vortex flipping driven by the ferromagnets magnetization. This is a direct consequence of proximity effect that leads to vortex supercurrents leakage into the ferromagnets. Here the polarized electron spins are subject to vortices magnetic field occasioning vortex flipping. Such novel mechanism has been made possible for the first time by fabrication of the F/S/F/AF multilayered spin valves with a thin-enough S layer to barely confine vortices inside as well as thin-enough F layers to align and control the magnetization within the plane. When Co is used there is no observation of vortex flipping effect. This is attributed to Co shorter coherence length. Interestingly instead a reduction in pinning field of about 400 Oe is observed when the Nb layer is in superconducting state. This effect cannot be explained in terms of vortex fields. In view of these facts any explanation must be directly related to proximity effect and thus a remarkable phenomenon that deserves further investigation. Programa Nacional de Ciencias Basicas COLCIENCIAS (No. 120452128168).

  4. Brucella Endocarditis in Prosthetic Valves

    Science.gov (United States)

    Mehanic, Snjezana; Mulabdic, Velida; Baljic, Rusmir; Hadzovic-Cengic, Meliha; Pinjo, Fikret; Hadziosmanovic, Vesna; Topalovic, Jasna

    2012-01-01

    SUMMARY CONFLICT OF INTEREST: none declared. Introduction Brucella endocarditis (BE) is a rare but severe and potentially lethal manifestation of brucellosis. Pre-existing valves lesions and prosthetic valves (PV) are favorable for BE. Case report We represent the case of a 46-year-old man who was treated at the Clinic for Infectious Diseases, Clinical Center of Sarajevo University, as blood culture positive (Brucella melitensis) mitral and aortic PV endocarditis. He was treated with combined anti-brucella and cardiac therapy. Surgical intervention was postponed due to cardiac instability. Four months later he passed away. Surgery was not performed. PMID:24493988

  5. A PSL Bounded Model Checking Method

    Institute of Scientific and Technical Information of China (English)

    YU Lei; ZHAO Zongtao

    2012-01-01

    SAT-based bounded model checking (BMC) is introduced as an important complementary technique to OBDD-based symbolic model checking, and is an efficient verification method for parallel and reactive systems. However, until now the properties verified by bounded model checking are very finite. Temporal logic PSL is a property specification language (IEEE-1850) describing parallel systems and is divided into two parts, i.e. the linear time logic FL and the branch time logic OBE. In this paper, the specification checked by BMC is extended to PSL and its algorithm is also proposed. Firstly, define the bounded semantics of PSL, and then reduce the bounded semantics into SAT by translating PSL specification formula and the state transition relation of the system to the propositional formula A and B, respectively. Finally, verify the satisfiability of the conjunction propositional formula of A and B. The algorithm results in the translation of the existential model checking of the temporal logic PSL into the satisfiability problem of propositional formula. An example of a queue controlling circuit is used to interpret detailedly the executing procedure of the algorithm.

  6. OPERATIONAL FAULT DIAGNOSIS IN INDUSTRIAL HYDRAULIC SYSTEMS THROUGH MODELING THE INTERNAL LEAKAGE OF ITS COMPONENTS

    Directory of Open Access Journals (Sweden)

    P. Athanasatos

    2013-01-01

    Full Text Available In this study, a model of a high pressure hydraulic system was developed using the bond graph method to investigate the effect of the internal leakage of its main components (pump, cylinder and 4/2 way valve on the operational characteristics of the system under various loads. All the main aspects of the hydraulic circuit (like the internal leakages, the compressibility of the fluid, the hydraulic pressure drop, the inertia of moving masses and the friction of the spool were taken into consideration. The results of this modeling were compared with the experimental data taken from the literature and from an actual test platform installed in the laboratory. Modeling and experimental data curves correlate very well in form, magnitude and response times for all the system’s main parameters. This proves that the present method can be used to accurately model the response and operation of hydraulic systems and can thus be used for operational fault diagnosis in many cases, especially in simulating fault scenarios when the defective component is not obvious. This is very important in industrial production systems where unpredictable shutdowns of the hydraulic machinery have a considerable negative economic impact on cost.

  7. Pressure relief valve/safety relief valve testing

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-02-01

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

  8. Whitey SCHE Gauge and Root Valves

    Energy Technology Data Exchange (ETDEWEB)

    MISKA, C.R.

    2000-09-11

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

  9. Whitey SCHE Gauge and Root Valves

    Energy Technology Data Exchange (ETDEWEB)

    MISKA, C.R.

    2000-09-03

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

  10. Miniature piezo electric vacuum inlet valve

    Science.gov (United States)

    Keville, Robert F.; Dietrich, Daniel D.

    1998-03-24

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

  11. 14 CFR 27.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 27.995 Section 27.995... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System Components § 27.995 Fuel valves. (a) There must be a positive, quick-acting valve to shut off fuel to each engine individually. (b) The control...

  12. 14 CFR 29.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 29.995 Section 29.995... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System Components § 29.995 Fuel valves. In addition to meeting the requirements of § 29.1189, each fuel valve must— (a) (b) Be supported so that no...

  13. 14 CFR 25.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 25.995 Section 25.995... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System Components § 25.995 Fuel valves. In addition to the requirements of § 25.1189 for shutoff means, each fuel valve must— (a) (b) Be supported...

  14. 14 CFR 29.1025 - Oil valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil valves. 29.1025 Section 29.1025... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Oil System § 29.1025 Oil valves. (a) Each oil shutoff.... (c) Each oil valve must have positive stops or suitable index provisions in the “on” and...

  15. 14 CFR 25.1025 - Oil valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil valves. 25.1025 Section 25.1025... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Oil System § 25.1025 Oil valves. (a) Each oil shutoff... feathering. (c) Each oil valve must have positive stops or suitable index provisions in the “on” and...

  16. 49 CFR 195.258 - Valves: General.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves: General. 195.258 Section 195.258... PIPELINE Construction § 195.258 Valves: General. (a) Each valve must be installed in a location that is accessible to authorized employees and that is protected from damage or tampering. (b) Each submerged...

  17. 14 CFR 121.239 - Oil valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Oil valves. 121.239 Section 121.239..., FLAG, AND SUPPLEMENTAL OPERATIONS Special Airworthiness Requirements § 121.239 Oil valves. (a) Each oil valve must— (1) Comply with § 121.257; (2) Have positive stops or suitable index provisions in the...

  18. 14 CFR 121.235 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Fuel valves. 121.235 Section 121.235..., FLAG, AND SUPPLEMENTAL OPERATIONS Special Airworthiness Requirements § 121.235 Fuel valves. Each fuel valve must— (a) Comply with § 121.257; (b) Have positive stops or suitable index provisions in the...

  19. Aerodynamic Characteristics of Tracheostomy Speaking Valves.

    Science.gov (United States)

    Fornataro-Clerici, Lisa; Zajac, David J.

    1993-01-01

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

  20. Staphylococcus saprophyticus causing native valve endocarditis.

    Science.gov (United States)

    Garduño, Eugenio; Márquez, Irene; Beteta, Alicia; Said, Ibrahim; Blanco, Javier; Pineda, Tomás

    2005-01-01

    Coagulase negative staphylococci are a rare cause of native valve endocarditis. Staphylococcus saprophyticus is a coagulase-negative Staphylococcus infrequently reported as a human pathogen, and most of the cases reported are urinary tract infections. We describe a case of native valve endocarditis attributed to this organism. The patient needed valve replacement due to heart failure.

  1. EM information leakage from display unit and visual inspection for its leakage source

    Science.gov (United States)

    Watanabe, Takashi; Sako, Hiroshi

    2013-05-01

    Display unit emits a small amount of electromagnetic wave. Although it is weak enough to prevent interference with human body, information leaks through it. This paper presents an experiment on exploring the leakage source by visually inspecting the screen images reconstructed from captured electromagnetic waves. Additionally, some countermeasures are investigated to avoid the problem.

  2. Leakage detection device for weld portion

    Energy Technology Data Exchange (ETDEWEB)

    Shinkawa, Toshio; Setokuchi, Sadayuki.

    1994-02-04

    The present invention concerns leakage detection device for weld portions, for example, in a nuclear reactor cavity, which can rapidly detect by remote control. That is, a detection device capable of self running and stopping on a guide rail along a weld line is disposed. The detection device comprises a coating mechanism for automatically coating soap water to the weld portion, a vacuum box capable of evacuating the coated surface and a camera for detecting the presence or absence of the soap bubbles generated under the evacuation. Such a device can conduct, by remote control, self running/stopping along with the weld line, coating of the soap water, settling of the vacuum box and confirmation and recording of foaming by using a television monitor. Accordingly, leakage in the weld portion in the reactor cavity or the like can be inspected. As a result, it greatly contributes to improvement of danger upon worker's operation at high place, detection accuracy and reliability of detection and shortening of operation period. (I.S.).

  3. Checking Timed Automata for Linear Duration Properties

    Institute of Scientific and Technical Information of China (English)

    赵建华

    2000-01-01

    It is proved in this paper that checking a timed automaton M with respect to a linear duration property D can be done by investigating only the integral timed states of M. An equivalence relation is introduced in this paper to divide the infinite number of integral timed states into finite number of equivalence classes. Based on this, a method is proposed for checking whether M satisfies D. In some cases, the number of equivalence classes is too large for a computer to manipulate. A technique for reducing the search-space for checking linear duration property is also described. This technique is more suitable for the case in this paper than those in the literature because most of those techniques are designed for reachability analysis.

  4. A Metric Encoding for Bounded Model Checking

    Science.gov (United States)

    Pradella, Matteo; Morzenti, Angelo; San Pietro, Pierluigi

    In Bounded Model Checking, both the system model and the checked property are translated into a Boolean formula to be analyzed by a SAT-solver. We introduce a new encoding technique which is particularly optimized for managing quantitative future and past metric temporal operators, typically found in properties of hard real time systems. The encoding is simple and intuitive in principle, but it is made more complex by the presence, typical of the Bounded Model Checking technique, of backward and forward loops used to represent an ultimately periodic infinite domain by a finite structure. We report and comment on the new encoding technique and on an extensive set of experiments carried out to assess its feasibility and effectiveness.

  5. Check Point任命新总裁

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    近日,互联网安全解决方案供应商Check Point软件技术有限公司宣布,Amnon Bar—Lev晋升为公司总裁。Bar--Lev将继续掌管公司面向客户的工作,包括销售、市场营销、业务发展、技术服务和合作伙伴计划。Bar—Lev于2005年加入Check Point,担任技术服务副总裁,并于2006年开始领导全球市场运营。在此期间,Check Point营业额增长了1倍多,达到约12亿美元。

  6. HCH for Checking Containment of XPath Fragment

    Institute of Scientific and Technical Information of China (English)

    Jian-Hua Feng; Yu-Guo Liao; Yong Zhang

    2007-01-01

    XPath is ubiquitous in XML applications for navigating XML trees and selecting a set of element nodes. In XPath query processing, one of the most important issues is how to efficiently check containment relationship between two XPath expressions. To get out of the intricacy and complexity caused by numerous XPath features, we investigate this issue on a frequently used fragment of XPath expressions that consists of node tests, the child axis (/), the descendant axis (//), branches ([]) and label wildcards (*). Prior work has shown that homomorphism technology can be used for containment checking. However, homomorphism is the sufficient but not necessary condition for containment. For special classes of this fragment, the homomorphism algorithm returns false negatives. To address this problem, this paper proposes two containment techniques, conditioned homomorphism and hidden conditioned homomorphism, and then presents sound algorithms for checking containment. Experimental results confirm the practicability and efficiency of the proposed algorithms.

  7. Graded CTL Model Checking for Test Generation

    CERN Document Server

    Napoli, Margherita

    2011-01-01

    Recently there has been a great attention from the scientific community towards the use of the model-checking technique as a tool for test generation in the simulation field. This paper aims to provide a useful mean to get more insights along these lines. By applying recent results in the field of graded temporal logics, we present a new efficient model-checking algorithm for Hierarchical Finite State Machines (HSM), a well established symbolism long and widely used for representing hierarchical models of discrete systems. Performing model-checking against specifications expressed using graded temporal logics has the peculiarity of returning more counterexamples within a unique run. We think that this can greatly improve the efficacy of automatically getting test cases. In particular we verify two different models of HSM against branching time temporal properties.

  8. Residential Forced Air System Cabinet Leakage and Blower Performance

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Iain S.; Dickerhoff, Darryl J.; Delp, William W.

    2010-03-01

    This project evaluated the air leakage and electric power consumption of Residential HVAC components, with a particular focus on air leakage of furnace cabinets. Laboratory testing of HVAC components indicated that air leakage can be significant and highly variable from unit to unit ? indicating the need for a standard test method and specifying maximum allowable air leakage in California State energy codes. To further this effort, this project provided technical assistance for the development of a national standard for Residential HVAC equipment air leakage. This standard is being developed by ASHRAE and is called"ASHRAE Standard 193P - Method of test for Determining the Air Leakage Rate of HVAC Equipment". The final part of this project evaluated techniques for measurement of furnace blower power consumption. A draft test procedure for power consumption was developed in collaboration with the Canadian General Standards Board: CSA 823"Performance Standard for air handlers in residential space conditioning systems".

  9. Leakage detection in earth dams by heated fiber optics

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Y.L.; Clerc, T.L.; Fabre, J.P.; Fry, J.J. [EDF, Grenoble (France); Royet, P. [CEMAGREF, Aix-en-Provence (France)

    2010-07-01

    Leakage detection is a major key to ensuring dam safety. Thermal methods based on distributed temperature measurement by means of fibre optics are currently among the most effective and promising means for identifying internal erosion processes. This paper investigated leakage detection in earth dams by use of heated fibre optics. After a description of the active method for leakage detection, the paper presented the validation of this detection method on a controlled experimental dike, the upstream drainage system of which was instrumented with fibre optics and where leakages were artificially provoked as well as on some real sites. The leakages were successfully located at both sites. The capability of the proposed method to estimate flow rates was demonstrated for the experimental basin. It was found that thermal monitoring by distributed measurements along bier optics is a powerful tool for detecting leakages in dikes.

  10. Distributed public key schemes secure against continual leakage

    DEFF Research Database (Denmark)

    Akavia, Adi; Goldwasser, Shafi; Hazay, Carmit

    2012-01-01

    In this work we study distributed public key schemes secure against continual memory leakage. The secret key will be shared among two computing devices communicating over a public channel, and the decryption operation will be computed by a simple 2-party protocol between the devices. Similarly...... against continual memory leakage, under the Bilinear Decisional Diffie-Hellman and $2$-linear assumptions. Our schemes have the following properties: 1. Our DPKE and DIBE schemes tolerate leakage at all times, including during refresh. During refresh the tolerated leakage is a (1/2-o (1),1)-fraction...... of the secret memory of P1, P2 respectively; and at all other times (post key generation) the tolerated leakage is a (1-o (1),1)-fraction of the secret memory of P1, P2 respectively. Our DIBE scheme tolerates leakage from both the master secret key and the identity based secret keys. Our DPKE scheme is CCA2...

  11. A Systematic Review of the Empirical Support for Check-in Check-Out

    Science.gov (United States)

    Wolfe, Katie; Pyle, Daniel; Charlton, Cade T.; Sabey, Christian V.; Lund, Emily M.; Ross, Scott W.

    2016-01-01

    Tier 2 interventions play an important role within the Positive Behavioral Interventions and Supports framework, bridging the gap between schoolwide Tier 1 interventions and individualized Tier 3 supports. Check-in Check-out (CICO) is a promising Tier 2 intervention for addressing mild problem behavior and potentially preventing the need for more…

  12. Function-Based Modification of Check-In/Check-Out to Influence Escape-Maintained Behavior

    Science.gov (United States)

    Kilgus, Stephen P.; Fallon, Lindsay M.; Feinberg, Adam B.

    2016-01-01

    Prior research has suggested Check-In/Check-Out (CICO) effectiveness is linked to the function of problem behavior. Though effective for students whose misbehavior occurs to gain attention, findings are equivocal for behavior that occurs to escape academic tasks. The purpose of this study was to therefore evaluate a modification to CICO, wherein…

  13. Check In / Check Out. The Public Space as an Internet of Things

    NARCIS (Netherlands)

    van t Hof, C.C.G.; van Est, R.; Daemen, F.

    2011-01-01

    Mobile phones, public transport smart cards, security cameras and GPS systems in our car - we are surrounded by digital devices. They track us, guide us, help us, and control us. The book Check In / Check Out. The Public Space as an Internet of Things shows us how our digital and physical worlds are

  14. Transanal stent in anterior resection does not prevent anastomotic leakage

    DEFF Research Database (Denmark)

    Bülow, Steffen; Bulut, O; Christensen, Ib Jarle;

    2006-01-01

    OBJECTIVE: A defunctioning transanal stent may theoretically reduce the leakage rate after anterior rectal resection. We present a randomized open study with the aim of comparing the leakage rate after anterior resection with a loop ileostomy, a transanal stent, both or neither. PATIENTS AND METH....... On this basis it was decided to discontinue the study prematurely for ethical reasons. CONCLUSION: Decompression of the anastomosis with a transanal stent does not reduce the risk of anastomotic leakage after anterior resection....

  15. Engineering Abstractions in Model Checking and Testing

    DEFF Research Database (Denmark)

    Achenbach, Michael; Ostermann, Klaus

    2009-01-01

    Abstractions are used in model checking to tackle problems like state space explosion or modeling of IO. The application of these abstractions in real software development processes, however, lacks engineering support. This is one reason why model checking is not widely used in practice yet...... and testing is still state of the art in falsification. We show how user-defined abstractions can be integrated into a Java PathFinder setting with tools like AspectJ or Javassist and discuss implications of remaining weaknesses of these tools. We believe that a principled engineering approach to designing...

  16. Gate-Check System for Outotec Company

    OpenAIRE

    Zajac, Lukas; Bartusek, Petr

    2014-01-01

    The main purpose of the thesis was to create the interactive, electronic web application Gate-Check for Outotec Company, which replaced the old system based on MS Excel document. Another purpose was gaining new skills and experiences in communication with the company, in which the team acted as a Supply Company. The created web application (Gate-Check System) should be compatible with any device with integrated web browser with support HTML5, JavaScript and CSS3 and active internet connect...

  17. A Method for Model Checking Feature Interactions

    DEFF Research Database (Denmark)

    Pedersen, Thomas; Le Guilly, Thibaut; Ravn, Anders Peter;

    2015-01-01

    This paper presents a method to check for feature interactions in a system assembled from independently developed concurrent processes as found in many reactive systems. The method combines and refines existing definitions and adds a set of activities. The activities describe how to populate the ...... the definitions with models to ensure that all interactions are captured. The method is illustrated on a home automation example with model checking as analysis tool. In particular, the modelling formalism is timed automata and the analysis uses UPPAAL to find interactions....

  18. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... polyester material that's used for -- it's basically a medical grade fabric. And again, I want to underscore that these tissue valves are hand-made in factories and undergo quite a bit of testing and tolerance before they ever reach our shelf. ...

  19. Hydraulic servo control spool valve

    Science.gov (United States)

    Miller, Donald M.

    1983-01-01

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

  20. Microprocessor-Based Valved Controller

    Science.gov (United States)

    Norman, Arnold M., Jr.

    1987-01-01

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

  1. Minimally Invasive Aortic Valve Replacement

    Medline Plus

    Full Text Available ... to know the human dynamic or blood pressure effects of a valvular problem and is also important with regards to determining coronary artery anatomy, as some patients may need coronary bypass surgery in addition to valve surgery. Exercise testing, as I mentioned previously, is a nice ...

  2. Effect of hinge gap width of a St. Jude medical bileaflet mechanical heart valve on blood damage potential--an in vitro micro particle image velocimetry study.

    Science.gov (United States)

    Jun, Brian H; Saikrishnan, Neelakantan; Arjunon, Sivakkumar; Yun, B Min; Yoganathan, Ajit P

    2014-09-01

    The hinge regions of the bileaflet mechanical heart valve (BMHV) can cause blood element damage due to nonphysiological shear stress levels and regions of flow stasis. Recently, a micro particle image velocimetry (μPIV) system was developed to study whole flow fields within BMHV hinge regions with enhanced spatial resolution under steady leakage flow conditions. However, global velocity maps under pulsatile conditions are still necessary to fully understand the blood damage potential of these valves. The current study hypothesized that the hinge gap width will affect flow fields in the hinge region. Accordingly, the blood damage potential of three St. Jude Medical (SJM) BMHVs with different hinge gap widths was investigated under pulsatile flow conditions, using a μPIV system. The results demonstrated that the hinge gap width had a significant influence during the leakage flow phase in terms of washout and shear stress characteristics. During the leakage flow, the largest hinge gap generated the highest Reynolds shear stress (RSS) magnitudes (~1000 N/m²) among the three valves at the ventricular side of the hinge. At this location, all three valves indicated viscous shear stresses (VSS) greater than 30 N/m². The smallest hinge gap exhibited the lowest level of shear stress values, but had the poorest washout flow characteristics among the three valves, demonstrating propensity for flow stasis and associated activated platelet accumulation potential. The results from this study indicate that the hinge is a critical component of the BMHV design, which needs to be optimized to find the appropriate balance between reduction in fluid shear stresses and enhanced washout during leakage flow, to ensure minimal thrombotic complications.

  3. Effect of hinge gap width of a St. Jude medical bileaflet mechanical heart valve on blood damage potential--an in vitro micro particle image velocimetry study.

    Science.gov (United States)

    Jun, Brian H; Saikrishnan, Neelakantan; Arjunon, Sivakkumar; Yun, B Min; Yoganathan, Ajit P

    2014-09-01

    The hinge regions of the bileaflet mechanical heart valve (BMHV) can cause blood element damage due to nonphysiological shear stress levels and regions of flow stasis. Recently, a micro particle image velocimetry (μPIV) system was developed to study whole flow fields within BMHV hinge regions with enhanced spatial resolution under steady leakage flow conditions. However, global velocity maps under pulsatile conditions are still necessary to fully understand the blood damage potential of these valves. The current study hypothesized that the hinge gap width will affect flow fields in the hinge region. Accordingly, the blood damage potential of three St. Jude Medical (SJM) BMHVs with different hinge gap widths was investigated under pulsatile flow conditions, using a μPIV system. The results demonstrated that the hinge gap width had a significant influence during the leakage flow phase in terms of washout and shear stress characteristics. During the leakage flow, the largest hinge gap generated the highest Reynolds shear stress (RSS) magnitudes (~1000 N/m²) among the three valves at the ventricular side of the hinge. At this location, all three valves indicated viscous shear stresses (VSS) greater than 30 N/m². The smallest hinge gap exhibited the lowest level of shear stress values, but had the poorest washout flow characteristics among the three valves, demonstrating propensity for flow stasis and associated activated platelet accumulation potential. The results from this study indicate that the hinge is a critical component of the BMHV design, which needs to be optimized to find the appropriate balance between reduction in fluid shear stresses and enhanced washout during leakage flow, to ensure minimal thrombotic complications. PMID:24976188

  4. Annex III. Implementation of condition monitoring techniques to improve valve reliability and performance

    International Nuclear Information System (INIS)

    Innovations in technology have provided for the development and use of sophisticated diagnostic systems for monitoring plant equipment such as motor-operated valves, pneumatic control valves, check valves and motors. This capability has in a sense allowed us to revise our plant maintenance philosophy concerning valves and motors in nuclear power plants from time-based maintenance practices to condition based maintenance (CBM). In the establishment of a predictive maintenance philosophy, the equipment's operability, working environment and risk significance are taken into consideration in determining the frequency of testing as well as the need for maintenance. The activities of several international nuclear organizations have kept pace with the technology and have initiated process improvements necessary to maximize the technical and economic benefits of condition based maintenance. This paper discusses adoption of valve and motor condition monitoring in the nuclear power industry, relevant documentation and research in this field, and recent efforts to combine risk assessment with condition monitoring strategies to achieve the highest level of reliability and safety without significantly affecting operation and maintenance cost. (author)

  5. Valve assembly having remotely replaceable bearings

    Science.gov (United States)

    Johnson, Evan R.; Tanner, David E.

    1980-01-01

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

  6. Control of rf leakage in the TRIUMF cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Dohan, D.; Fong, K.; Pacak, V.

    1986-10-01

    The TRIUMF vacuum chamber and beam gap form a cavity with resonant rf modes close to the operating frequency. The resultant leakage into this beam cavity poses significant problems to beam diagnostic equipment and can damage non-cooled components in this volume. Model studies, machine measurements and theoretical calculations have been carried out in order to understand and control the leakage. The amount of this rf leakage is shown to depend critically on the alignment at the dee gap. Two dominant leakage modes have been identified and their excitation mechanisms have been studied. The total leakage field depends critically on the amplitudes and phases of these parasitic modes. Through suitable superposition of these modes, the leakage can be reduced and its pattern modified by the realignment of the top and bottom ground arm tips. Reductions in the leakage by 10 to 15 dB have been achieved on the model and on the machine. The major cause of heating of the resonator strongbacks has been found to be due not to the leakage currents themselves, but to multipactoring effects in the beam cavity driven by leakage electric fields.

  7. Vertebroplasty: Magnetic Resonance Findings Related to Cement Leakage Risk

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Y.H.; Han, D.; Cha, J.H.; Seong, C.K.; Kim, J.; Choi, Y.H. [Dept. of Radiology, Seoul Municipal Boramae Hospital, Seoul (Korea, republic of)

    2007-04-15

    Purpose: To find magnetic resonance (MR) findings predicting cement leakage in patients receiving percutaneous vertebroplasty (PVP) due to osteoporotic compression fractures. Material and Methods: MR was done in 43 patients (age 52-89 years) before PVP (56 vertebrae), which was done via a bipedicular approach with fluoroscopic monitoring. Shortly after the procedure, a non-contrast-enhanced computed tomography (CT) scan was done at the vertebroplasty sites for evaluation of bone cement leakage. The following MR findings of fractured vertebral bodies were retrospectively reviewed for correlation with leakage risk: severity of bone-marrow edema, presence of a T2-weighted low-signal-intensity line, percentage residual vertebral body height, presence of either a vacuum or cystic change within the vertebral body, and presence of a cortical disruption. Results: After PVP, cement leakage was detected in 35 vertebrae (62.5%). Leakage was most frequently observed in the anterior external vertebral venous plexus (46%). Cement leakage rate increased when there was a cortical disruption (P = 0.037), especially at the endplates, while it decreased when there was a vacuum or a cystic change within the fractured vertebra (P 0.019). Other MR findings were not related to the risk of cement leakage. Conclusion: The risk of cement leakage in PVP increases when MR shows cortical disruption in a fractured vertebral body, especially at the endplates. It decreases when MR shows a vacuum or cystic change within the body. Keywords Cement leakage, MR imaging, spine, vertebroplasty.

  8. Influence of Slot Defect Length on Magnetic Flux Leakage

    Institute of Scientific and Technical Information of China (English)

    Songling HUANG; Luming LI; Haiqing YANG; Keren SHI

    2004-01-01

    A key issue, which influences the applications of magnetic flux leakage testing, is defect quantification. There have been many research on the relationship between width, depth and magnetic flux leakage of slot defect. However, the length factor is often ignored. The relationship between characteristics of defect leakage field and defect length was investigated. The magnetic flux leakages of a series of plate specimens with the same width, same depth and different length slot defects were tested under the same magnetizing conditions. Testing results show that defect length is an important parameter needed to consider in quantifying defects.

  9. Mitral Valve Repair: The Chordae Tendineae

    Directory of Open Access Journals (Sweden)

    Carlos-A Mestres

    2015-10-01

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

  10. Leakage of high active liquid waste into the thermowell of HALW evaporator (4/4). Repair work for leakage prevention

    International Nuclear Information System (INIS)

    Leakage of high active liquid waste into the thermowell of High Active Liquid Waste (HALW) Evaporator was confirmed when thermometers were replaced in Rokkasho Reprocessing Plant. We estimate that the cause of the leakage is tunnel corrosion at the bottom cap of the thermowell due to high temperature at the bottom of the evaporator. This paper deals with the repair work for the leakage prevention. (author)

  11. A Facility for Accurate Heat Load and Mass Leak Measurements on Superfluid Helium Valves

    CERN Document Server

    Bézaguet, Alain-Arthur; Ferlin, G; Losserand-Madoux, R; Perin, A; Vandoni, Giovanna; Van Weelderen, R

    1999-01-01

    The superconducting magnets of the Large Hadron Collider (LHC) will be protected by safety relief valves operating at 1.9 K in superfluid helium (HeII). A test facility was developed to precisely determine the heat load and the mass leakage of cryogenic valves with HeII at their inlet. The temperature of the valve inlet can be varied from 1.8 K to 2 K for pressures up to 3.5 bar. The valve outlet pipe temperature can be regulated between 5 K and 20 K. The heat flow is measured with high precision using a Kapitza-resistance heatmeter and is also crosschecked by a vaporization measurement. After calibration, a precision of 10 mW for heat flows up to 1.1 W has been achieved. The helium leak can be measured up to 15 mg/s with an accuracy of 0.2 mg/s. We present a detailed description of the test facility and the measurements showing its performances.

  12. Manipulation of the closing transients of bileaflet mechanical heart valves using passive, surface-mounted elements

    Science.gov (United States)

    Simon, Helene

    2005-11-01

    The time-periodic closing of bileaflet mechanical heart valves is accompanied by a strong flow transient that is associated with the formation of a counter-rotating vortex pair near the b-datum line of leaflet edges. The strong transitory shear that is generated by these vortices may be damaging to blood elements and may result in platelet activation. In the present work, these flow transients are mitigated using miniature vortex generator arrays that are embedded on the surface of the leaflets. The closing transients in the absence and presence of the passive vortex generators are characterized using PIV measurements that are phase locked to the leaflet motion. The study utilizes a 25 mm St. Jude Medical valve placed in the aortic position of the Georgia Tech left heart simulator. The valve is subjected to physiological flow conditions: a heart rate of 70 bpm; a cardiac output of 5 l/min; and a mean aortic pressure of 90 mmHg. Measurements of the velocity field in the center plane of the leaflets demonstrate that the dynamics of the transient vortices that precede the formation of the leakage jets can be significantly altered and controlled by relatively simple passive modifications of existing valve designs.

  13. Check list of European Hymenomycetous Heterobasidiae

    NARCIS (Netherlands)

    Donk, M.A.

    1966-01-01

    With this check list an attempt is made to account for the recorded European species of those Basidiomycetes that Patouillard called the “Hétérobasidies”, excluding, however, the Uredinales and Ustilaginales. Therefore, it covers the Septobasidiales, Tremellales (comprising the Auriculariineae and T

  14. Model Checking as Static Analysis: Revisited

    DEFF Research Database (Denmark)

    Zhang, Fuyuan; Nielson, Flemming; Nielson, Hanne Riis

    2012-01-01

    We show that the model checking problem of the μ-calculus can be viewed as an instance of static analysis. We propose Succinct Fixed Point Logic (SFP) within our logical approach to static analysis as an extension of Alternation-free Least Fixed Logic (ALFP). We generalize the notion...

  15. Incremental Integrity Checking: Limitations and Possibilities

    DEFF Research Database (Denmark)

    Christiansen, Henning; Martinenghi, Davide

    2005-01-01

    to query containment, we show that no procedure exists that always returns the best incremental test (aka simplification of integrity constraints), and this according to any reasonable criterion measuring the checking effort. In spite of this theoretical limitation, we develop an effective procedure...

  16. Efficient CSL Model Checking Using Stratification

    DEFF Research Database (Denmark)

    Zhang, Lijun; Jansen, David N.; Nielson, Flemming;

    2012-01-01

    For continuous-time Markov chains, the model-checking problem with respect to continuous-time stochastic logic (CSL) has been introduced and shown to be decidable by Aziz, Sanwal, Singhal and Brayton in 1996 [ 1, 2]. Their proof can be turned into an approximation algorithm with worse than expone...

  17. Explicit State Model Checking for Graph Grammars

    NARCIS (Netherlands)

    Rensink, A.; De Nicola, R.; Degano, P.; Meseguer, J.

    2008-01-01

    In this paper we present the philosophy behind the GROOVE project, in which graph transformation is used as a modelling formalism on top of which a model checking approach to software verification is being built. We describe the basic formalism, the current state of the project, and (current and fut

  18. Anchor Stress Checking of Security Injection Tank

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The intention of the calculating is to check the anchor stresses of the security injection tank to know whether the stress is satisfied the code requirements on the basis of all the reaction forces gained in the static, seismic and thermal stress results.

  19. Using chemical organization theory for model checking

    OpenAIRE

    Kaleta, Christoph; Richter, Stephan; Dittrich, Peter

    2009-01-01

    Motivation: The increasing number and complexity of biomodels makes automatic procedures for checking the models' properties and quality necessary. Approaches like elementary mode analysis, flux balance analysis, deficiency analysis and chemical organization theory (OT) require only the stoichiometric structure of the reaction network for derivation of valuable information. In formalisms like Systems Biology Markup Language (SBML), however, information about the stoichiometric coefficients re...

  20. Availability of a Renewable, Checked System

    DEFF Research Database (Denmark)

    Platz, O.

    1976-01-01

    Recurrent expressions are given for point and interval unavailability of a renewable system subjected to periodic checking/repair. The expressions are generalizations of the basic relations in the theory of discrete renewal processes. The asymptotic limits for long times follow simply from a...