Science.gov

Sample records for absolute leak rate

  1. Leak rate estimation of a resistive plate chamber gap by monitoring absolute pressure

    NASA Astrophysics Data System (ADS)

    Mondal, S.; Datar, V. M.; Kalmani, S. D.; Majumder, G.; Mondal, N. K.; Satyanarayana, B.

    2016-11-01

    The differential pressure of a conventional manometer is highly dependent on the atmospheric pressure. The measurements with a manometer for an extended time period show a large variation due to solar atmospheric tides. However, the measurements of absolute pressure, both outside and inside of a resistive plate chamber (RPC), are independent of each other. By monitoring the absolute pressures, both outside and inside of a RPC, along with the temperature, its leakage rate can be estimated. During the test period, the supporting button spacers inside a RPC may get detached due to some manufacturing defect. This effect can be detected clearly by observing the sudden fall of pressure inside the chamber.

  2. Variable gas leak rate valve

    DOEpatents

    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.

  3. Experiences with leak rate calculations methods for LBB application

    SciTech Connect

    Grebner, H.; Kastner, W.; Hoefler, A.; Maussner, G.

    1997-04-01

    In this paper, three leak rate computer programs for the application of leak before break analysis are described and compared. The programs are compared to each other and to results of an HDR Reactor experiment and two real crack cases. The programs analyzed are PIPELEAK, FLORA, and PICEP. Generally, the different leak rate models are in agreement. To obtain reasonable agreement between measured and calculated leak rates, it was necessary to also use data from detailed crack investigations.

  4. Probabilistic pipe fracture evaluations for leak-rate-detection applications

    SciTech Connect

    Rahman, S.; Ghadiali, N.; Paul, D.; Wilkowski, G.

    1995-04-01

    Regulatory Guide 1.45, {open_quotes}Reactor Coolant Pressure Boundary Leakage Detection Systems,{close_quotes} was published by the U.S. Nuclear Regulatory Commission (NRC) in May 1973, and provides guidance on leak detection methods and system requirements for Light Water Reactors. Additionally, leak detection limits are specified in plant Technical Specifications and are different for Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs). These leak detection limits are also used in leak-before-break evaluations performed in accordance with Draft Standard Review Plan, Section 3.6.3, {open_quotes}Leak Before Break Evaluation Procedures{close_quotes} where a margin of 10 on the leak detection limit is used in determining the crack size considered in subsequent fracture analyses. This study was requested by the NRC to: (1) evaluate the conditional failure probability for BWR and PWR piping for pipes that were leaking at the allowable leak detection limit, and (2) evaluate the margin of 10 to determine if it was unnecessarily large. A probabilistic approach was undertaken to conduct fracture evaluations of circumferentially cracked pipes for leak-rate-detection applications. Sixteen nuclear piping systems in BWR and PWR plants were analyzed to evaluate conditional failure probability and effects of crack-morphology variability on the current margins used in leak rate detection for leak-before-break.

  5. Compact Instruments Measure Helium-Leak Rates

    NASA Technical Reports Server (NTRS)

    Stout, Stephen; Immer, Christopher

    2003-01-01

    Compact, lightweight instruments have been developed for measuring small flows of helium and/or detecting helium leaks in solenoid valves when the valves are nominally closed. These instruments do not impede the flows when the valves are nominally open. They can be integrated into newly fabricated valves or retrofitted to previously fabricated valves. Each instrument includes an upstream and a downstream thermistor separated by a heater, plus associated analog and digital heater-control, signal- conditioning, and data-processing circuits. The thermistors and heater are off-the-shelf surface mount components mounted on a circuit board in the flow path. The operation of the instrument is based on a well-established thermal mass-flow-measurement technique: Convection by the flow that one seeks to measure gives rise to transfer of heat from the heater to the downstream thermistor. The temperature difference measured by the thermistors is directly related to the rate of flow. The calibration curve from temperature gradient to helium flow is closely approximated via fifth-order polynomial. A microprocessor that is part of the electronic circuitry implements the calibration curve to compute the flow rate from the thermistor readings.

  6. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak...

  7. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak...

  8. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak...

  9. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak...

  10. 40 CFR 1065.644 - Vacuum-decay leak rate.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Vacuum-decay leak rate. 1065.644 Section 1065.644 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.644 Vacuum-decay leak...

  11. The concepts of leak before break and absolute reliability of NPP equipment and piping

    SciTech Connect

    Getman, A.F.; Komarov, O.V.; Sokov, L.M.

    1997-04-01

    This paper describes the absolute reliability (AR) concept for ensuring safe operation of nuclear plant equipment and piping. The AR of a pipeline or component is defined as the level of reliability when the probability of an instantaneous double-ended break is near zero. AR analysis has been applied to Russian RBMK and VVER type reactors. It is proposed that analyses required for application of the leak before break concept should be included in AR implementation. The basic principles, methods, and approaches that provide the basis for implementing the AR concept are described.

  12. LEAK: A source term generator for evaluating release rates from leaking vessels

    SciTech Connect

    Clinton, J.H.

    1994-09-01

    An interactive computer code for estimating the rate of release of any one of several materials from a leaking tank or broken pipe leading from a tank is presented. It is generally assumed that the material in the tank is liquid. Materials included in the data base are acetonitrile, ammonia, carbon tetrachloride, chlorine, chlorine trifluoride, fluorine, hydrogen fluoride, nitric acid, nitrogen tetroxide, sodium hydroxide, sulfur hexafluoride, sulfuric acid, and uranium hexafluoride. Materials that exist only as liquid and/or vapor over expected ranges of temperature and pressure can easily be added to the data base file. The Fortran source code for LEAK and the data file are included with this report.

  13. Absolute rate theories of epigenetic stability

    NASA Astrophysics Data System (ADS)

    Walczak, Aleksandra M.; Onuchic, José N.; Wolynes, Peter G.

    2005-12-01

    Spontaneous switching events in most characterized genetic switches are rare, resulting in extremely stable epigenetic properties. We show how simple arguments lead to theories of the rate of such events much like the absolute rate theory of chemical reactions corrected by a transmission factor. Both the probability of the rare cellular states that allow epigenetic escape and the transmission factor depend on the rates of DNA binding and unbinding events and on the rates of protein synthesis and degradation. Different mechanisms of escape from the stable attractors occur in the nonadiabatic, weakly adiabatic, and strictly adiabatic regimes, characterized by the relative values of those input rates. rate theory | stochastic gene expression | gene switches

  14. Absolute Rate Theories of Epigenetic Stability

    NASA Astrophysics Data System (ADS)

    Walczak, Aleksandra M.; Onuchic, Jose N.; Wolynes, Peter G.

    2006-03-01

    Spontaneous switching events in most characterized genetic switches are rare, resulting in extremely stable epigenetic properties. We show how simple arguments lead to theories of the rate of such events much like the absolute rate theory of chemical reactions corrected by a transmission factor. Both the probability of the rare cellular states that allow epigenetic escape, and the transmission factor, depend on the rates of DNA binding and unbinding events and on the rates of protein synthesis and degradation. Different mechanisms of escape from the stable attractors occur in the nonadiabatic, weakly adiabatic and strictly adiabatic regimes, characterized by the relative values of those input rates.

  15. 105-KE Isolation Barrier Leak Rate Acceptance Test Report

    SciTech Connect

    McCracken, K.J.

    1995-06-14

    This Acceptance Test Report (ATR) contains the completed and signed Acceptance Procedure (ATP) for the 105-KE Isolations Barrier Leak Rate Test. The Test Engineer`s log, the completed sections of the ATP in the Appendix for Repeat Testing (Appendix K), the approved WHC J-7s (Appendix H), the data logger files (Appendices T and U), and the post test calibration checks (Appendix V) are included.

  16. Leak rate analysis of the Westinghouse Reactor Coolant Pump

    SciTech Connect

    Boardman, T.; Jeanmougin, N.; Lofaro, R.; Prevost, J.

    1985-07-01

    An independent analysis was performed by ETEC to determine what the seal leakage rates would be for the Westinghouse Reactor Coolant Pump (RCP) during a postulated station blackout resulting from loss of ac electric power. The object of the study was to determine leakage rates for the following conditions: Case 1: All three seals function. Case 2: No. 1 seal fails open while Nos. 2 and 3 seals function. Case 3: All three seals fail open. The ETEC analysis confirmed Westinghouse calculations on RCP seal performance for the conditions investigated. The leak rates predicted by ETEC were slightly lower than those predicted by Westinghouse for each of the three cases as summarized below. Case 1: ETEC predicted 19.6 gpm, Westinghouse predicted 21.1 gpm. Case 2: ETEC predicted 64.7 gpm, Westinghouse predicted 75.6 gpm. Case 3: ETEC predicted 422 gpm, Westinghouse predicted 480 gpm. 3 refs., 22 figs., 6 tabs.

  17. Temperature and Atomic Oxygen Effects on Helium Leak Rates of a Candidate Main Interface Seal

    NASA Technical Reports Server (NTRS)

    Penney, Nicholas; Wasowski, Janice L.; Daniels, Christopher C.

    2011-01-01

    Helium leak tests were completed to characterize the leak rate of a 54 in. diameter composite space docking seal design in support of the National Aeronautics and Space Administration s (NASA's) Low Impact Docking System (LIDS). The evaluated seal design was a candidate for the main interface seal on the LIDS, which would be compressed between two vehicles, while docked, to prevent the escape of breathable air from the vehicles and into the vacuum of space. Leak tests completed at nominal temperatures of -30, 20, and 50 C on untreated and atomic oxygen (AO) exposed test samples were examined to determine the influence of both test temperature and AO exposure on the performance of the composite seal assembly. Results obtained for untreated seal samples showed leak rates which increased with increased test temperature. This general trend was not observed in tests of the AO exposed specimens. Initial examination of collected test data suggested that AO exposure resulted in higher helium leak rates, however, further analysis showed that the differences observed in the 20 and 50 C tests between the untreated and AO exposed samples were within the experimental error of the test method. Lack of discernable trends in the test data prevented concrete conclusions about the effects of test temperature and AO exposure on helium leak rates of the candidate seal design from being drawn. To facilitate a comparison of the current test data with results from previous leak tests using air as the test fluid, helium leak rates were converted to air leak rates using standard conversion factors for viscous and molecular flow. Flow rates calculated using the viscous flow conversion factor were significantly higher than the experimental air leakage values, whereas values calculated using the molecular flow conversion factor were significantly lower than the experimentally obtained air leak rates. The difference in these sets of converted flow rates and their deviation from the

  18. Evaluation and refinement of leak-rate estimation models. Revision 1

    SciTech Connect

    Paul, D.D.; Ahmad, J.; Scott, P.M.; Flanigan, L.F.; Wilkowski, G.M.

    1994-06-01

    Leak-rate estimation models are important elements in developing a leak-beforebreak methodology in piping integrity and safety analyses. Existing thermalhydraulic and crack-opening-area models used in current leak-rate estimations have been incorporated into a single computer code for leak-rate estimation. The code is called SQUIRT, which stands for Seepage Quantification of Upsets In Reactor Tubes. The SQUIRT program has been validated by comparing its thermalhydraulic predictions with the limited experimental data that have been published on two-phase flow through slits and cracks, and by comparing its crack-opening-area predictions with data from the Degraded Piping Program. In addition, leak-rate experiments were conducted to obtain validation data for a circumferential fatigue crack in a carbon steel pipe girth weld.

  19. USING AN ADAPTER TO PERFORM THE CHALFANT-STYLE CONTAINMENT VESSEL PERIODIC MAINTENANCE LEAK RATE TEST

    SciTech Connect

    Loftin, B.; Abramczyk, G.; Trapp, D.

    2011-06-03

    Recently the Packaging Technology and Pressurized Systems (PT&PS) organization at the Savannah River National Laboratory was asked to develop an adapter for performing the leak-rate test of a Chalfant-style containment vessel. The PT&PS organization collaborated with designers at the Department of Energy's Pantex Plant to develop the adapter currently in use for performing the leak-rate testing on the containment vessels. This paper will give the history of leak-rate testing of the Chalfant-style containment vessels, discuss the design concept for the adapter, give an overview of the design, and will present results of the testing done using the adapter.

  20. Using airborne measurements and modelling to determine the leak rate of the Elgin platform in 2012

    NASA Astrophysics Data System (ADS)

    Mobbs, Stephen D.; Bauguitte, Stephane J.-B.; Wellpott, Axel; O'Shea, Sebastian

    2013-04-01

    On the 25th March 2012 the French multinational oil and gas company Total reported a gas leak at the Elgin gas field in the North Sea following an operation on well G4 on the wellhead platform. During operations to plug and decommission the well methane leaked out which lead to the evacuation of the platform. Total made immense efforts to quickly stop the leak and on the 16th May 2012 the company announced the successful "Top kill". The UK's National Centre for Atmospheric Science (NCAS) supported the Total response to the leak with flights of the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft. Between the 3rd of April and the 4th of May five missions were flown. The FAAM aircraft was equipped with a Fast Greenhouse Gas Analyser (FGGA, Model RMT-200, Los Gatos Research Inc., US) to measure CH4 mixing ratios with an accuracy of 0.07±2.48 ppbv. The measurement strategy used followed closely NOAA's during the Deepwater Horizon (DWH) spill in the Gulf of Mexico in 2010. The basis of the method is to sample the cross-wind structure of the plume at different heights downwind of the source. The measurements were then fitted to a Gaussian dispersion model which allowed the calculation of the leak rate. The first mission was flown on the 30th March 2012 only 5 days after Total reported the leak. On this day maximum CH4 concentrations exceeded 2800 ppbv. The plume was very distinct and narrow especially near the platform (10km) and it showed almost perfect Gaussian characteristics. Further downwind the plume was split up into several filaments. On this day the CH4 leak rate was estimated to be 1.1 kg/s. Between the 1st and 2nd mission (03/04/2012) the leak rate decreased significantly to about 0.5 kg/s. From the 2nd flight onwards only a minor decrease in leak rate was calculated. The last mission - while the platform was still leaking - was flown on the 4th of May, when the leak rate was estimated to be 0.3 kg/s. The FAAM aircraft measurements

  1. An Experimental Investigation of Leak Rate Performance of a Subscale Candidate Elastomer Docking Space Seal

    NASA Technical Reports Server (NTRS)

    Garafolo, Nicholas G.; Daniels, Christopher C.

    2011-01-01

    A novel docking seal was developed for the main interface seal of NASA s Low Impact Docking System (LIDS). This interface seal was designed to maintain acceptable leak rates while being exposed to the harsh environmental conditions of outer space. In this experimental evaluation, a candidate docking seal assembly called Engineering Development Unit (EDU58) was characterized and evaluated against the Constellation Project leak rate requirement. The EDU58 candidate seal assembly was manufactured from silicone elastomer S0383-70 vacuum molded in a metal retainer ring. Four seal designs were considered with unique characteristic heights. The leak rate performance was characterized through a mass point leak rate method by monitoring gas properties within an internal control volume. The leakage performance of the seals were described herein at representative docking temperatures of -50, +23, and +50 C for all four seal designs. Leak performance was also characterized at 100, 74, and 48 percent of full closure. For all conditions considered, the candidate seal assemblies met the Constellation Project leak rate requirement.

  2. Pharmaceutical container/closure integrity. II: The relationship between microbial ingress and helium leak rates in rubber-stoppered glass vials.

    PubMed

    Kirsch, L E; Nguyen, L; Moeckly, C S; Gerth, R

    1997-01-01

    Helium leak rate measurements were quantitatively correlated to the probability of microbial ingress for rubber-stoppered glass vials subjected to immersion challenge. Standard 10-mL tubing glass vials were modified by inserting micropipettes of various sizes (0.1 to 10 microns nominal diameter) into a side wall hole and securing them with epoxy. Butyl rubber closures and aluminum crimps were used to seal the vials. The test units were sealed in a helium-filled glove bag, then the absolute helium leak rates were determined. The test units were disassembled, filled with media, resealed, and autoclaved. The test units were thermally treated to eliminate airlocks within the micropipette lumen and establish a liquid path between microbial challenge media and the test units' contents. Microbial challenge was performed by immersing the test units in a 35 degrees C bath containing magnesium ion and 8 to 10 logs of viable P. diminuta and E. coli for 24 hours. The test units were then incubated at 35 degrees C for an additional 13 days. Microbial ingress was detected by turbidity and plating on blood agar. The elimination of airlocks was confirmed by the presence of magnesium ions in the vial contents by atomic absorption spectrometry. A total of 288 vials were subjected to microbial challenge testing. Those test units whose contents failed to show detectable magnesium ions were eliminated from further analysis. At large leak rates, the probability of microbial ingress approached 100% and at very low leak rates microbial ingress rates were 0%. A dramatic increase in microbial failure occurred in the leak rate region 10(-4.5) to 10(-3) std cc/sec, which roughly corresponded to leak diameters ranging from 0.4 to 2 microns. Below a leak rate of 10(-4.5) std cc/sec the microbial failure rate was < 10%. The critical leak rate in our studies, i.e. the value below which microbial ingress cannot occur because the leak is too small, was observed to be between 10(-5) and 10(-5.8) std

  3. Assessment of crack opening area for leak rates

    SciTech Connect

    Sharples, J.K.; Bouchard, P.J.

    1997-04-01

    This paper outlines the background to recommended crack opening area solutions given in a proposed revision to leak before break guidance for the R6 procedure. Comparisons with experimental and analytical results are given for some selected cases of circumferential cracks in cylinders. It is shown that elastic models can provide satisfactory estimations of crack opening displacement (and area) but they become increasingly conservative for values of L{sub r} greater than approximately 0.4. The Dugdale small scale yielding model gives conservative estimates of crack opening displacement with increasing enhancement for L{sub r} values greater than 0.4. Further validation of the elastic-plastic reference stress method for up to L{sub r} values of about 1.0 is presented by experimental and analytical comparisons. Although a more detailed method, its application gives a best estimate of crack opening displacement which may be substantially greater than small scale plasticity models. It is also shown that the local boundary conditions in pipework need to be carefully considered when evaluating crack opening area for through-wall bending stresses resulting from welding residual stresses or geometry discontinuities.

  4. Leak Rate Quantification Method for Gas Pressure Seals with Controlled Pressure Differential

    NASA Technical Reports Server (NTRS)

    Daniels, Christopher C.; Braun, Minel J.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.

    2015-01-01

    An enhancement to the pressure decay leak rate method with mass point analysis solved deficiencies in the standard method. By adding a control system, a constant gas pressure differential across the test article was maintained. As a result, the desired pressure condition was met at the onset of the test, and the mass leak rate and measurement uncertainty were computed in real-time. The data acquisition and control system were programmed to automatically stop when specified criteria were met. Typically, the test was stopped when a specified level of measurement uncertainty was attained. Using silicone O-ring test articles, the new method was compared with the standard method that permitted the downstream pressure to be non-constant atmospheric pressure. The two methods recorded comparable leak rates, but the new method recorded leak rates with significantly lower measurement uncertainty, statistical variance, and test duration. Utilizing this new method in leak rate quantification, projects will reduce cost and schedule, improve test results, and ease interpretation between data sets.

  5. The effect of metabolic depression on proton leak rate in mitochondria from hibernating frogs.

    PubMed

    St-Pierre, J; Brand, M D; Boutilier, R G

    2000-05-01

    Futile cycling of protons across the mitochondrial inner membrane accounts for 20 % or more of the total standard metabolic rate of a rat. Approximately 15 % of this total is due to proton leakage inside the skeletal muscle alone. This study examined whether the rate of proton leak is down-regulated as a part of a coordinated response to energy conservation during metabolic depression in cold-submerged frogs. We compared the proton leak rate of skeletal muscle mitochondria isolated from frogs at different stages of hibernation (control, 1 month and 4 months of submergence in normoxia and hypoxia). The kinetics of mitochondrial proton leak rate was unaltered throughout normoxic and hypoxic submergence. The state 4 respiration rates did not differ between control animals and frogs hibernating in normoxia. In contrast, the state 4 respiration rates obtained from frogs submerged in hypoxic water for 4 months were half those of control animals. This 50 % reduction in respiration rate in hypoxic hibernation was due to a reduction in electron transport chain activity and consequent decrease in mitochondrial membrane potential. We conclude that proton leak rate is reduced during metabolic depression as a secondary result of a decrease in electron transport chain activity, but that the proton conductance is unchanged. In addition, we show that the rate of proton leakage and the activity of the electron transport chain are lower in frogs than in rats, strengthening the observation that mitochondria from ectotherms have a lower proton conductance than mitochondria from endotherms.

  6. Anastomotic leak rate after low anterior resection for rectal cancer after chemoradiation therapy.

    PubMed

    Phillips, Benjamin R; Harris, Lisa J; Maxwell, Pinckney J; Isenberg, Gerald A; Goldstein, Scott D

    2010-08-01

    Anastomotic leak may be the most concerning complication after colorectal anastomosis. To compare open with laparoscopic rectal resection, we must have accurate leak rates in patients who have received neoadjuvant chemoradiation therapy to serve as a benchmark for comparison. All patients who had preoperative chemoradiation therapy with rectal resection and low pelvic anastomosis for cancer in a single colorectal practice over a 7-year period were retrospectively reviewed. All patients had proximal diversion and a contrast enema study before stoma reversal. Eighty-seven consecutive patients were included in the study. Average age was 58 years. Fifty-nine per cent of patients were male. Sixty-six per cent were smokers. Pathologic T stage was 5 per cent T0, 16 per cent T1, 28 per cent T2, 47 per cent T3, and 5 per cent T4. Seventy-five per cent of patients were pathologically lymph node-negative. Average time to stoma reversal was 122 days. Total anastomotic leak rate was 10.3 per cent (8% clinical leaks). Five (56%) patients with leak successfully underwent reversal of their diverting stoma (average time to reversal, 290 days). Patients who had the complication of anastomotic leakage had less likelihood of stoma reversal and a significantly prolonged time to stoma reversal.

  7. Estimation of Leak Rate from the Emergency Pump Well in L-Area Complex Basin

    SciTech Connect

    Duncan, A

    2005-12-19

    This report provides an estimate of the leak rate from the emergency pump well in L-basin that is to be expected during an off-normal event. This estimate is based on expected shrinkage of the engineered grout (i.e., controlled low strength material) used to fill the emergency pump well and the header pipes that provide the dominant leak path from the basin to the lower levels of the L-Area Complex. The estimate will be used to provide input into the operating safety basis to ensure that the water level in the basin will remain above a certain minimum level. The minimum basin water level is specified to ensure adequate shielding for personnel and maintain the ''as low as reasonably achievable'' concept of radiological exposure. The need for the leak rate estimation is the existence of a gap between the fill material and the header pipes, which penetrate the basin wall and would be the primary leak path in the event of a breach in those pipes. The gap between the pipe and fill material was estimated based on a full scale demonstration pour that was performed and examined. Leak tests were performed on full scale pipes as a part of this examination. Leak rates were measured to be on the order of 0.01 gallons/minute for completely filled pipe (vertically positioned) and 0.25 gallons/minute for partially filled pipe (horizontally positioned). This measurement was for water at 16 feet head pressure and with minimal corrosion or biofilm present. The effect of the grout fill on the inside surface biofilm of the pipes is the subject of a previous memorandum.

  8. Influence of wetting effect at the outer surface of the pipe on increase in leak rate - experimental results and discussion

    SciTech Connect

    Isozaki, Toshikuni; Shibata, Katsuyuki

    1997-04-01

    Experimental and computed results applicable to Leak Before Break analysis are presented. The specific area of investigation is the effect of the temperature distribution changes due to wetting of the test pipe near the crack on the increase in the crack opening area and leak rate. Two 12-inch straight pipes subjected to both internal pressure and thermal load, but not to bending load, are modelled. The leak rate was found to be very susceptible to the metal temperature of the piping. In leak rate tests, therefore, it is recommended that temperature distribution be measured precisely for a wide area.

  9. Leak Rate Performance of Silicone Elastomer O-Rings Contaminated with JSC-1A Lunar Regolith Simulant

    NASA Technical Reports Server (NTRS)

    Oravec, Heather Ann; Daniels, Christopher C.

    2014-01-01

    Contamination of spacecraft components with planetary and foreign object debris is a growing concern. Face seals separating the spacecraft cabin from the debris filled environment are particularly susceptible; if the seal becomes contaminated there is potential for decreased performance, mission failure, or catastrophe. In this study, silicone elastomer O-rings were contaminated with JSC- 1A lunar regolith and their leak rate performance was evaluated. The leak rate values of contaminated O-rings at four levels of seal compression were compared to those of as-received, uncontaminated, O-rings. The results showed a drastic increase in leak rate after contamination. JSC-1A contaminated O-rings lead to immeasurably high leak rate values for all levels of compression except complete closure. Additionally, a mechanical method of simulant removal was examined. In general, this method returned the leak rate to as-received values.

  10. Pharmaceutical container/closure integrity. III: Validation of the helium leak rate method for rigid pharmaceutical containers.

    PubMed

    Kirsch, L E; Nguyen, L; Gerth, R

    1997-01-01

    Validation of a helium leak rate method for pharmaceutical container/closure integrity quality assurance required the demonstration that this physical testing method was as good or better than microbial immersion challenge testing in detecting potential integrity failures. One lot of rubber-stoppered, broth-filled glass vials also containing defective vials with known leaks were subjected to both helium leak rate and microbial challenge testing. The defective vials were prepared by affixing glass micropipettes (0.1 to 10 microns) into the vial side walls. The validation lot included a 10% seeded defect rate of which about 50% contained leaks with a predicted probability of failing a microbial challenge (> 10%). Helium tracer was placed in the test units by charging them for 4 hours under a 40 psi helium pressure. The critical leak rate after charging was determined to be 10(-7) standard cc/second, and test units with measured leak rates greater than this value were considered helium leak rate failures. Microbial immersion challenge was conducted by exposing the test units in a bath inoculated with 10(9-10) viable E. coli and B. diminuta organisms for 24 hours followed by a 13 day (35 degrees C) incubation. Microbial failures were determined visually. The helium and microbial leak test methods were compared statistically using mean failure rates. The mean helium failure rate was 6.9%, whereas the mean microbial failure rate was 2.8%. The difference between helium and microbial failure rates was significantly greater than zero. Thus, helium leak rate testing was demonstrated to be a suitable pharmaceutical container/closure integrity method for microbial quality assurance of rigid containers.

  11. Verification of International Space Station Component Leak Rates by Helium Accumulation Method

    NASA Technical Reports Server (NTRS)

    Underwood, Steve D.; Smith, Sherry L.

    2003-01-01

    Discovery of leakage on several International Space Station U.S. Laboratory Module ammonia system quick disconnects (QDs) led to the need for a process to quantify total leakage without removing the QDs from the system. An innovative solution was proposed allowing quantitative leak rate measurement at ambient external pressure without QD removal. The method utilizes a helium mass spectrometer configured in the detector probe mode to determine helium leak rates inside a containment hood installed on the test component. The method was validated through extensive developmental testing. Test results showed the method was viable, accurate and repeatable for a wide range of leak rates. The accumulation method has been accepted by NASA and is currently being used by Boeing Huntsville, Boeing Kennedy Space Center and Boeing Johnson Space Center to test welds and valves and will be used by Alenia to test the Cupola. The method has been used in place of more expensive vacuum chamber testing which requires removing the test component from the system.

  12. Pressure Decay Testing Methodology for Quantifying Leak Rates of Full-Scale Docking System Seals

    NASA Technical Reports Server (NTRS)

    Dunlap, Patrick H., Jr.; Daniels, Christopher C.; Wasowski, Janice L.; Garafolo, Nicholas G.; Penney, Nicholas; Steinetz, Bruce M.

    2010-01-01

    NASA is developing a new docking system to support future space exploration missions to low-Earth orbit and the Moon. This system, called the Low Impact Docking System, is a mechanism designed to connect the Orion Crew Exploration Vehicle to the International Space Station, the lunar lander (Altair), and other future Constellation Project vehicles. NASA Glenn Research Center is playing a key role in developing the main interface seal for this docking system. This seal will be relatively large with an outside diameter in the range of 54 to 58 in. (137 to 147 cm). As part of this effort, a new test apparatus has been designed, fabricated, and installed to measure leak rates of candidate full-scale seals under simulated thermal, vacuum, and engagement conditions. Using this test apparatus, a pressure decay testing and data processing methodology has been developed to quantify full-scale seal leak rates. Tests performed on untreated 54 in. diameter seals at room temperature in a fully compressed state resulted in leak rates lower than the requirement of less than 0.0025 lbm, air per day (0.0011 kg/day).

  13. Determination of crack morphology parameters from service failures for leak-rate analyses

    SciTech Connect

    Wilkowski, G.; Ghadiali, N.; Paul, D.

    1997-04-01

    In leak-rate analyses described in the literature, the crack morphology parameters are typically not well agreed upon by different investigators. This paper presents results on a review of crack morphology parameters determined from examination of service induced cracks. Service induced cracks were found to have a much more tortuous flow path than laboratory induced cracks due to crack branching associated with the service induced cracks. Several new parameters such as local and global surface roughnesses, as well as local and global number of turns were identified. The effect of each of these parameters are dependent on the crack-opening displacement. Additionally, the crack path is typically assumed to be straight through the pipe thickness, but the service data show that the flow path can be longer due to the crack following a fusion line, and/or the number of turns, where the number of turns in the past were included as a pressure drop term due to the turns, but not the longer flow path length. These parameters were statistically evaluated for fatigue cracks in air, corrosion-fatigue, IGSCC, and thermal fatigue cracks. A refined version of the SQUIRT leak-rate code was developed to account for these variables. Sample calculations are provided in this paper that show how the crack size can vary for a given leak rate and the statistical variation of the crack morphology parameters.

  14. On the probability of exceeding allowable leak rates through degraded steam generator tubes

    SciTech Connect

    Cizelj, L.; Sorsek, I.; Riesch-Oppermann, H.

    1997-02-01

    This paper discusses some possible ways of predicting the behavior of the total leak rate through the damaged steam generator tubes. This failure mode is of special concern in cases where most through-wall defects may remain In operation. A particular example is the application of alternate (bobbin coil voltage) plugging criterion to Outside Diameter Stress Corrosion Cracking at the tube support plate intersections. It is the authors aim to discuss some possible modeling options that could be applied to solve the problem formulated as: Estimate the probability that the sum of all individual leak rates through degraded tubes exceeds the predefined acceptable value. The probabilistic approach is of course aiming at reliable and computationaly bearable estimate of the failure probability. A closed form solution is given for a special case of exponentially distributed individual leak rates. Also, some possibilities for the use of computationaly efficient First and Second Order Reliability Methods (FORM and SORM) are discussed. The first numerical example compares the results of approximate methods with closed form results. SORM in particular shows acceptable agreement. The second numerical example considers a realistic case of NPP in Krsko, Slovenia.

  15. Video-rate spectral imaging of gas leaks in the longwave infrared

    NASA Astrophysics Data System (ADS)

    Hagen, Nathan; Kester, Robert T.; Morlier, Christopher G.; Panek, Jeffrey A.; Drayton, Paul; Fashimpaur, Dave; Stone, Paul; Adams, Elizabeth

    2013-05-01

    We have recently constructed and tested a gas cloud imager which demonstrates the rst-ever video-rate detection (15 frames/sec) of gas leaks using an uncooled LWIR detector array. Laboratory and outdoor measurements, taken in collaboration with BP Products North America Inc. and IES Inc., show detection sensitivities comparable to existing cooled systems for detecting hydrocarbon gases. Gases imaged for these experiments include methane, propane, propylene, ethane, ethylene, butane, and iso-butylene, but any gases with absorption features in the LWIR band could potentially be detected, such as sarin and other toxic gases. These results show that practical continuous monitoring of gas leaks with uncooled imaging sensors is now possible.

  16. Assessments of fluid friction factors for use in leak rate calculations

    SciTech Connect

    Chivers, T.C.

    1997-04-01

    Leak before Break procedures require estimates of leakage, and these in turn need fluid friction to be assessed. In this paper available data on flow rates through idealized and real crack geometries are reviewed in terms of a single friction factor k It is shown that for {lambda} < 1 flow rates can be bounded using correlations in terms of surface R{sub a} values. For {lambda} > 1 the database is less precise, but {lambda} {approx} 4 is an upper bound, hence in this region flow calculations can be assessed using 1 < {lambda} < 4.

  17. Payload and Components Real-Time Automated Test System (PACRATS), Data Acquisition of Leak Rate and Pressure Data Test Procedure

    NASA Technical Reports Server (NTRS)

    Rinehart, Maegan L.

    2011-01-01

    The purpose of this activity is to provide the Mechanical Components Test Facility (MCTF) with the capability to obtain electronic leak test and proof pressure data, Payload and Components Real-time Automated Test System (PACRATS) data acquisition software will be utilized to display real-time data. It will record leak rates and pressure/vacuum level(s) simultaneously. This added functionality will provide electronic leak test and pressure data at specified sampling frequencies. Electronically stored data will provide ES61 with increased data security, analysis, and accuracy. The tasks performed in this procedure are to verify PACRATS only, and are not intended to provide verifications for MCTF equipment.

  18. Full-Scale System for Quantifying Loads and Leak Rates of Seals for Space Applications

    NASA Technical Reports Server (NTRS)

    Dunlap, Patrick H., Jr.; Steinetz, Bruce M.; Daniels, Christopher C.; Wasowski, Janice L.; Robbie, Malcolm G.; Erker, Arthur H.; Drlik, Gary J.; Mayer, John J.

    2010-01-01

    NASA is developing advanced space-rated vacuum seals in support of future space exploration missions to low-Earth orbit and other destinations. These seals may be 50 to 60 in. (127 to 152 cm) in diameter and must exhibit extremely low leak rates to ensure that astronauts have sufficient breathable air for extended missions to the International Space Station or the Moon. Seal compression loads must be below prescribed limits so as not to overload the mechanisms that compress them during docking or mating, and seal adhesion forces must be low to allow two mated systems to separate when required. NASA Glenn Research Center has developed a new test apparatus to measure leak rates and compression and adhesion loads of candidate full-scale seals under simulated thermal, vacuum, and engagement conditions. Tests can be performed in seal-on-seal or seal-on-flange configurations at temperatures from -76 to 140 F (-60 to 60 C) under operational pressure gradients. Nominal and off-nominal mating conditions (e.g., incomplete seal compression) can also be simulated. This paper describes the main design features of the test apparatus as well as techniques used to overcome some of the design challenges.

  19. Crack shape developments and leak rates for circumferential complex-cracked pipes

    SciTech Connect

    Brickstad, B.; Bergman, M.

    1997-04-01

    A computerized procedure has been developed that predicts the growth of an initial circumferential surface crack through a pipe and further on to failure. The crack growth mechanism can either be fatigue or stress corrosion. Consideration is taken to complex crack shapes and for the through-wall cracks, crack opening areas and leak rates are also calculated. The procedure is based on a large number of three-dimensional finite element calculations of cracked pipes. The results from these calculations are stored in a database from which the PC-program, denoted LBBPIPE, reads all necessary information. In this paper, a sensitivity analysis is presented for cracked pipes subjected to both stress corrosion and vibration fatigue.

  20. Sellar Reconstruction and Rates of Delayed Cerebrospinal Fluid Leak after Endoscopic Pituitary Surgery

    PubMed Central

    Sanders-Taylor, Chris; Anaizi, Amjad; Kosty, Jennifer; Zimmer, Lee A.; Theodosopoulos, Phillip V.

    2015-01-01

    Objectives Delayed cerebrospinal fluid (CSF) leaks are a complication in transsphenoidal surgery, potentially causing morbidity and longer hospital stays. Sella reconstruction can limit this complication, but is it necessary in all patients? Design Retrospective review. Setting Single-surgeon team (2005–2012) addresses this trend toward graded reconstruction. Participants A total of 264 consecutive patients with pituitary adenomas underwent endoscopic transsphenoidal resections. Sellar defects sizable to accommodate a fat graft were reconstructed. Main outcomes Delayed CSF leak and autograft harvesting. Results Overall, 235 (89%) had reconstruction with autograft (abdominal fat, septal bone/cartilage) and biological glue. Delayed CSF leak was 1.9%: 1.7%, and 3.4% for reconstructed and nonreconstructed sellar defects, respectively (p = 0.44). Complications included one reoperation for leak, two developed meningitis, and autograft harvesting resulted in abdominal hematoma in 0.9% and wound infection in 0.4%. Conclusion In our patients, delayed CSF leaks likely resulted from missed intraoperative CSF leaks or postoperative changes. Universal sellar reconstruction can preemptively treat missed leaks and provide a barrier for postoperative changes. When delayed CSF leaks occurred, sellar reconstruction often allowed for conservative treatment (i.e., lumbar drain) without repeat surgery. We found universal reconstruction provides a low risk of delayed CSF leak with minimal complications. PMID:26225317

  1. Space Station Freedom seal leakage rate analysis and testing summary: Air leaks in ambient versus vacuum exit conditions

    NASA Technical Reports Server (NTRS)

    Rodriguez, P. I.; Markovitch, R.

    1992-01-01

    This report is intended to reveal the apparent relationship of air seal leakage rates between 2 atmospheres (atm) to 1 atm and 1 atm to vacuum conditions. Gas dynamics analysis is provided as well as data summarizing the MSFC test report, 'Space Station Freedom (S.S. Freedom) Seal Flaw Study With Delta Pressure Leak Rate Comparison Test Report'.

  2. Determining the Discharge Rate from a Submerged Oil Leaks using ROV Video and CFD study

    NASA Astrophysics Data System (ADS)

    Saha, Pankaj; Shaffer, Frank; Shahnam, Mehrdad; Savas, Omer; Devites, Dave; Steffeck, Timothy

    2016-11-01

    The current paper reports a technique to measure the discharge rate by analyzing the video from a Remotely Operated Vehicle (ROV). The technique uses instantaneous images from ROV video to measure the velocity of visible features (turbulent eddies) along the boundary of an oil leak jet and subsequently classical theory of turbulent jets is imposed to determine the discharge rate. The Flow Rate Technical Group (FRTG) Plume Team developed this technique that manually tracked the visible features and produced the first accurate government estimates of the oil discharge rate from the Deepwater Horizon (DWH). For practical application this approach needs automated control. Experiments were conducted at UC Berkeley and OHMSETT that recorded high speed, high resolution video of submerged dye-colored water or oil jets and subsequently, measured the velocity data employing LDA and PIV software. Numerical simulation have been carried out using experimental submerged turbulent oil jets flow conditions employing LES turbulence closure and VOF interface capturing technique in OpenFOAM solver. The CFD results captured jet spreading angle and jet structures in close agreement with the experimental observations. The work was funded by NETL and DOI Bureau of Safety and Environmental Enforcement (BSEE).

  3. Greenhouse gas impacts of natural gas: Influence of deployment choice, methane leak rate, and methane GWP

    NASA Astrophysics Data System (ADS)

    Cohan, D. S.

    2015-12-01

    Growing supplies of natural gas have heightened interest in the net impacts of natural gas on climate. Although its production and consumption result in greenhouse gas emissions, natural gas most often substitutes for other fossil fuels whose emission rates may be higher. Because natural gas can be used throughout the sectors of the energy economy, its net impacts on greenhouse gas emissions will depend not only on the leak rates of production and distribution, but also on the use for which natural gas is substituted. Here, we present our estimates of the net greenhouse gas emissions impacts of substituting natural gas for other fossil fuels for five purposes: light-duty vehicles, transit buses, residential heating, electricity generation, and export for electricity generation overseas. Emissions are evaluated on a fuel cycle basis, from production and transport of each fuel through end use combustion, based on recent conditions in the United States. We show that displacement of existing coal-fired electricity and heating oil furnaces yield the largest reductions in emissions. The impact of compressed natural gas replacing petroleum-based vehicles is highly uncertain, with the sign of impact depending on multiple assumptions. Export of liquefied natural gas for electricity yields a moderate amount of emissions reductions. We further show how uncertainties in upstream emission rates for natural gas and in the global warming potential of methane influence the net greenhouse gas impacts. Our presentation will make the case that how natural gas is deployed is crucial to determining how it will impact climate.

  4. Chlorofluorocarbon leak detection technology

    SciTech Connect

    Munday, E.B.

    1990-12-01

    There are about 590 large coolant systems located at the Portsmouth Gaseous Diffusion Plant (PORTS) and the Paducah Gaseous Diffusion Plant (PGDP) leaking nearly 800,000 lb of R-114 refrigerant annually (1989 estimate). A program is now under way to reduce the leakage to 325,000 lb/year -- an average loss of 551 lb/year (0.063 lb/h) per coolant system, some of which are as large as 800 ft. This report investigates leak detection technologies that can be used to locate leaks in the coolant systems. Included are descriptions, minimum leak detection rate levels, advantages, disadvantages, and vendor information on the following technologies: bubbling solutions; colorimetric leak testing; dyes; halogen leak detectors (coronea discharge detectors; halide torch detectors, and heated anode detectors); laser imaging; mass spectroscopy; organic vapor analyzers; odorants; pressure decay methods; solid-state electrolytic-cell gas sensors; thermal conductivity leak detectors; and ultrasonic leak detectors.

  5. Guidelines to achieve seals with minimal leak rates for HWR-NPR coolant system components

    SciTech Connect

    Finn, P.A.

    1991-03-01

    Seal design practices that are acceptable in pressurized-water and boiling-water reactors in the United States are not usable for the Heavy Water Reactor-New Production Reactor (HWR-NPR) because of the stringent requirement on tritium control for the atmosphere within its containment building. To maintain an atmosphere in which workers do not need protective equipment, the components of the coolant system must have a cumulative leak rate less than 0.00026 L/s. Existing technology for seal systems was reviewed with regard to flange, elastomer, valve, and pump design. A technology data base for the designers of the HWR-NPR coolant system was derived from operating experience and seal development work on reactors in the United States, Canada, and Europe. This data base was then used to generate guidelines for the design of seals and/or joints for the HWR-NPR coolant system. Also discussed are needed additional research and development, as well as the necessary component qualification tests for an effective quality control program. 141 refs., 21 figs., 14 tabs.

  6. Leak Rate Test for a Fiber Beam Monitor Contained in a Vacuum for the Muon g-2 Experiment

    NASA Astrophysics Data System (ADS)

    O'Mara, Bridget; Lane, Noel; Gross, Eisen; Gray, Frederick; Muon g-2 Collaboration

    2014-09-01

    The muon g-2 experiment at Fermilab aims to measure the muon anomalous magnetic moment with a precision of 0.14 parts per million (ppm). The measurement will build on the Brookhaven-based E821 experiment, which yielded results suggesting new physics such as supersymmetry. The Fiber Beam Monitors (FBMs) are used in the experiment to determine the position and observe the motion of a muon beam and monitor the properties of the beam over time. The FBMs support a 9 cm × 8 cm ``harp'' with 7 scintillating fibers separated from each other by 13 mm, each with a diameter of 0.5 mm. The experiment requires a vacuum of less than 1 ×10-6 Torr to prevent trapping of electrons ionized from the residual gas by the electrostatic quadrupoles. To meet this requirement the FBMs must have a leak rate of less than 5 ×10-5 Torr L/s. We have constructed a vacuum system to simulate these conditions and have determined the leak rate of the FBMs within the constructed vacuum apparatus. This leak rate will be reported, along with preliminary results from tests of the light output from the scintillating fibers. The muon g-2 experiment at Fermilab aims to measure the muon anomalous magnetic moment with a precision of 0.14 parts per million (ppm). The measurement will build on the Brookhaven-based E821 experiment, which yielded results suggesting new physics such as supersymmetry. The Fiber Beam Monitors (FBMs) are used in the experiment to determine the position and observe the motion of a muon beam and monitor the properties of the beam over time. The FBMs support a 9 cm × 8 cm ``harp'' with 7 scintillating fibers separated from each other by 13 mm, each with a diameter of 0.5 mm. The experiment requires a vacuum of less than 1 ×10-6 Torr to prevent trapping of electrons ionized from the residual gas by the electrostatic quadrupoles. To meet this requirement the FBMs must have a leak rate of less than 5 ×10-5 Torr L/s. We have constructed a vacuum system to simulate these conditions

  7. Leak detection/verification

    SciTech Connect

    Krhounek, V.; Zdarek, J.; Pecinka, L.

    1997-04-01

    Loss of coolant accident (LOCA) experiments performed as part of a Leak Before Break (LBB) analysis are very briefly summarized. The aim of these experiments was to postulate the leak rates of the coolant. Through-wall cracks were introduced into pipes by fatigue cycling and hydraulically loaded in a test device. Measurements included coolant pressure and temperature, quantity of leaked coolant, displacement of a specimen, and acoustic emission. Small cracks were plugged with particles in the coolant during testing. It is believed that plugging will have no effect in cracks with leak rates above 35 liters per minute. The leak rate safety margin of 10 is sufficient for cracks in which the leak rate is more than 5 liters per minute.

  8. Determining Methane Leak Locations and Rates with a Wireless Network Composed of Low-Cost, Printed Sensors

    NASA Astrophysics Data System (ADS)

    Smith, C. J.; Kim, B.; Zhang, Y.; Ng, T. N.; Beck, V.; Ganguli, A.; Saha, B.; Daniel, G.; Lee, J.; Whiting, G.; Meyyappan, M.; Schwartz, D. E.

    2015-12-01

    We will present our progress on the development of a wireless sensor network that will determine the source and rate of detected methane leaks. The targeted leak detection threshold is 2 g/min with a rate estimation error of 20% and localization error of 1 m within an outdoor area of 100 m2. The network itself is composed of low-cost, high-performance sensor nodes based on printed nanomaterials with expected sensitivity below 1 ppmv methane. High sensitivity to methane is achieved by modifying high surface-area-to-volume-ratio single-walled carbon nanotubes (SWNTs) with materials that adsorb methane molecules. Because the modified SWNTs are not perfectly selective to methane, the sensor nodes contain arrays of variously-modified SWNTs to build diversity of response towards gases with adsorption affinity. Methane selectivity is achieved through advanced pattern-matching algorithms of the array's ensemble response. The system is low power and designed to operate for a year on a single small battery. The SWNT sensing elements consume only microwatts. The largest power consumer is the wireless communication, which provides robust, real-time measurement data. Methane leak localization and rate estimation will be performed by machine-learning algorithms built with the aid of computational fluid dynamics simulations of gas plume formation. This sensor system can be broadly applied at gas wells, distribution systems, refineries, and other downstream facilities. It also can be utilized for industrial and residential safety applications, and adapted to other gases and gas combinations.

  9. Development and verification of methods for predicting flow rates through leaks in valves and couplings

    NASA Technical Reports Server (NTRS)

    Russell, John M.

    1993-01-01

    This is the final report of a research effort which addresses the title problem. The report discusses two broad models of flows, which represent the following extreme cases: (1) inertia-dominated flow, where friction is relatively insignificant; and (2) friction-dominated flow where inertia is insignificant. In class (2), the leak channel might consist of the gap between a scratch in a plastic seal and a polished metal plate against which the seal is pressed. Here, the cross section of the leak channel is modeled as a flat bottomed crescent. A publication generated under the present grant period presents an exact solution of the equations of fully-developed laminar pipe flow of a liquid in the case of a crescent beneath a hyperbolic arc. A Master's thesis project supported by the present grant presents the corresponding solution beneath a circular arc. A second publication reviews the flow of a gas through the same channel, which may be analyzed by a standard one-dimensional model (Fanno flow) for an engineering approximation. Finally, the report discusses the design and progress in the fabrication of a leak-test cell, in which one may measure the flow of fluid through a controlled flaw in a seal. The aim of such measurements is to furnish data for comparison with the predictions of the theory.

  10. Absolute and Relative Reliability of Percentage of Syllables Stuttered and Severity Rating Scales

    ERIC Educational Resources Information Center

    Karimi, Hamid; O'Brian, Sue; Onslow, Mark; Jones, Mark

    2014-01-01

    Purpose: Percentage of syllables stuttered (%SS) and severity rating (SR) scales are measures in common use to quantify stuttering severity and its changes during basic and clinical research conditions. However, their reliability has not been assessed with indices measuring both relative and absolute reliability. This study was designed to provide…

  11. Permanent underwater leak detector

    NASA Astrophysics Data System (ADS)

    Costello, L.; McStay, D.; Moodie, D.; Kane, D.

    2009-07-01

    A new optoelectronic sensor for the real time monitoring of key components such as valves and connectors within the subsea production equipment for leaks of hydraulic fluid is reported. The sensor is capable of detecting low concentrations of such fluids, allowing the early detection of small leaks, and the ability to monitor the evolution of the leak-rate with time, hence providing an important new tool in complying with environmental requirements, enabling early intervention and optimising subsea production

  12. Absolute rate of the reaction of hydrogen atoms with ozone from 219-360 K

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Michael, J. V.; Payne, W. A.; Stief, L. J.

    1978-01-01

    Absolute rate constants for the reaction of atomic hydrogen with ozone were obtained over the temperature range 219-360 K by the flash photolysis-resonance fluorescence technique. The results can be expressed in Arrhenius form by K = (1.33 plus or minus 0.32)x10 to the minus 10 power exp (-449 plus or minus 58/T) cu cm/molecule/s (two standard deviations). The present work is compared to two previous determinations and is discussed theoretically.

  13. The unsettled world of leak rate physics: 1 atm large-volume considerations do not apply to MEMS packages: a practitioner's perspective

    NASA Astrophysics Data System (ADS)

    Kullberg, Richard C.; Jonath, Arthur; Lowry, Robert K.

    2012-03-01

    The world of leak testing, and the applicable physics, is unsettled. While globally lower MIL-STD leak rate criteria are under consideration even for 1 atm-large volume packages, industry is conversely moving rapidly into very small volume MEMS and vacuum packaging for advanced devices. These changes point out serious conceptual disconnects between the reality of properly characterizing a leak and the conceptual tools used to ensure the desired lifetime. The physical understandings and associated tool sets used to test and model the leaks are described. We modeled two actual packages, a large, ~200 cc volume multichip module for aerospace applications and a small ~0.01cc volume MEMS package for sensor applications. Impacts of various physical models of leak flow into a package are compared to include Fickian Diffusion, The Davy Model, Howl-Mann, and an empirically derived model based on Kr-85 leak testing as called out in the most recent edition of MIL-STD-883. As shown in the comparisons, simple He leak testing and physical models based thereon fall apart in the small volume MEMS packaging space.

  14. Absolute Density Calibration Cell for Laser Induced Fluorescence Erosion Rate Measurements

    NASA Technical Reports Server (NTRS)

    Domonkos, Matthew T.; Stevens, Richard E.

    2001-01-01

    Flight qualification of ion thrusters typically requires testing on the order of 10,000 hours. Extensive knowledge of wear mechanisms and rates is necessary to establish design confidence prior to long duration tests. Consequently, real-time erosion rate measurements offer the potential both to reduce development costs and to enhance knowledge of the dependency of component wear on operating conditions. Several previous studies have used laser-induced fluorescence (LIF) to measure real-time, in situ erosion rates of ion thruster accelerator grids. Those studies provided only relative measurements of the erosion rate. In the present investigation, a molybdenum tube was resistively heated such that the evaporation rate yielded densities within the tube on the order of those expected from accelerator grid erosion. This work examines the suitability of the density cell as an absolute calibration source for LIF measurements, and the intrinsic error was evaluated.

  15. Absolute rate coefficients for the recombination of open f-shell tungsten ions

    NASA Astrophysics Data System (ADS)

    Krantz, C.; Spruck, K.; Badnell, N. R.; Becker, A.; Bernhardt, D.; Grieser, M.; Hahn, M.; Novotný, O.; Repnow, R.; Savin, D. W.; Wolf, A.; Müller, A.; Schippers, S.

    2014-04-01

    We have carried out direct measurements of the absolute recombination rate coefficients of four charge states of tungsten in the range from W18+ to W21+ in a heavy ion storage ring. We find that the rich atomic fine structure of the open f-shell leads to very high resonant enhancement of the recombination rate at energies below ~50 eV. Even in the higher energy domain relevant to fusion plasma this leads to a recombination rate coefficient that is more than four times higher than predicted by the commonly used ADAS database of recombination rates. In addition to the experimental measurements we have carried out theoretical calculations using Autostructure. For W20+ these predict a plasma recombination rate coefficient that agrees much better with the measurement than the ADAS model but still fail to reproduce the experimental data in detail.

  16. Absolute rate constant for the reaction of Cl(/sup 2/P) with CINO

    SciTech Connect

    Nesbitt, F.L.; Nava, D.F.; Payne, W.A.; Stief, L.J.

    1987-09-24

    The room temperature rate constant for the reaction Cl + CINO yields Cl/sub 2/ + NO has been measured by the method of discharge flow mass spectrometry. The rate constant was determined from the decay of CINO in the presence of an excess of Cl atoms at a total pressure of 1 Torr. The rate constant obtained was (7.6 +/- 0.8) X 10/sup -11/ cm/sup 3/ s/sup -1/. This result is compared with previous determinations, the values of which ranged by more than an order of magnitude and all of which depended on knowledge of the absolute concentration of CINO. The authors suggest that the lack of agreement is attributable principally to uncertainties in (CINO) resulting from absorption of this reactive species on glass and metal surfaces. Our result does not depend directly on (CINO) and supports the highest values published for this rate constant.

  17. Leak checking in ISABELLE

    SciTech Connect

    Briggs, J.; Halama, H.J.

    1981-01-01

    The Intersecting Storage Accelerator (ISABELLE) contains two completely independent vacuum systems. One known as Beam Vacuum operates at 1 x 10/sup -11/ Torr and maintains a very clean environment for the circulating proton beam. The other system known as Insulating Vacuum maintains superconducting magnet vessels at a pressure below 1 x 10/sup -6/ Torr. In this system all gasses except helium are cryocondensed on the cold surfaces of superconducting magnets and cryogenic circuits. Turbomolecular pumps pump the inadvertent small helium leaks. The helium background both in the MagCOOL area and in the ISABELLE tunnel limits the sensitivity of conventional leak detectors. Leak detection in ISABELLE is one of the most important functions, since there are thousands of bellows and welds operating at 4 K and at 15 atmosphere pressure and that many welds can only be leak checked at room temperature. Leak rates are known to increase by 4 orders of magnitude when cooled from 300 K to 4 K. Thus the required 10/sup -10/ Torr liters s/sup -1/ sensitivity is essential for proper operation and methods and equipment which permit the location of such leaks in large systems have been developed and tested on the First Cell and the refrigerators. They produced a completely leak free system, i.e. the helium background did not change when all pumps were closed for 24 hours. These methods and the equipment are discussed in detail.

  18. Automated leak test systems

    SciTech Connect

    Cordaro, J.V.; Thompson, W.D.; Reeves, G.

    1997-09-15

    An automated leak test system for tritium shipping containers has been developed at Westinghouse Savannah River Co. (WSRC). The leak detection system employs a computer controlled helium detector which allows an operator to enter key information when prompted. The software for controlling the tests and the equipment apparatus were both designed and manufactured at the Savannah River Technology Center within WSRC. Recertification Test: Every twelve months, the pressure vessel portion of the shipping container itself must undergo a rigorous recertification leak test. After an empty pressure vessel (shipping container) is assembled, it is placed into one of six stainless steel belljars for helium leak testing. The belljars are fashioned in row much the same as assembly line arrangement. Post-load Test: A post-load leak test is performed upon reservoirs that have been filled with tritium and placed inside the shipping containers mentioned above. These leak tests are performed by a rate-of-rise method where the area around the shipping container seals is evacuated, valved off from the vacuum pump, and then the vacuum pressure is monitored over a two-minute period. The Post Load Leak Test is a quality verification test to ensure that the shipping container has been correctly assembled. 2 figs.

  19. Absolute determination of the Na22(p,γ)Mg23 reaction rate in novae

    NASA Astrophysics Data System (ADS)

    Sallaska, A. L.; Wrede, C.; García, A.; Storm, D. W.; Brown, T. A. D.; Ruiz, C.; Snover, K. A.; Ottewell, D. F.; Buchmann, L.; Vockenhuber, C.; Hutcheon, D. A.; Caggiano, J. A.; José, J.

    2011-03-01

    Gamma-ray telescopes in orbit around the earth are searching for evidence of the elusive radionuclide Na22 produced in novae. Previously published uncertainties in the dominant destructive reaction, Na22(p,γ)Mg23, indicated new measurements in the proton energy range of 150 to 300 keV were needed to constrain predictions. We have measured the resonance strengths, energies, and branches directly and absolutely by using protons from the University of Washington accelerator with a specially designed beam line, which included beam rastering and cold vacuum protection of the Na22 implanted targets. The targets, fabricated at TRIUMF-ISAC, displayed minimal degradation over a ~20 C bombardment as a result of protective layers. We avoided the need to know the absolute stopping power, and hence the target composition, by extracting resonance strengths from excitation functions integrated over proton energy. Our measurements revealed that resonance strengths for Ep=213, 288, 454, and 610 keV are stronger by factors of 2.4-3.2 than previously reported. Upper limits have been placed on proposed resonances at 198, 209, and 232 keV. These substantially reduce the uncertainty in the reaction rate. We have re-evaluated the Na22(p,γ) reaction rate, and our measurements indicate the resonance at 213 keV makes the most significant contribution to Na22 destruction in novae. Hydrodynamic simulations including our rate indicate that the expected abundance of Na22 ejecta from a classical nova is reduced by factors between 1.5 and 2, depending on the mass of the white-dwarf star hosting the nova explosion.

  20. Acceptance test procedure for the 105-KW isolation barrier leak rate

    SciTech Connect

    McCracken, K.J.

    1995-05-19

    This acceptance test procedure shall be used to: First establish a basin water loss rate prior to installation of the two isolation barriers between the main basin and the discharge chute in K-Basin West. Second, perform an acceptance test to verify an acceptable leakage rate through the barrier seals. This Acceptance Test Procedure (ATP) has been prepared in accordance with CM-6-1 EP 4.2, Standard Engineering Practices.

  1. The Br+HO 2 reaction revisited: Absolute determination of the rate constant at 298 K

    NASA Astrophysics Data System (ADS)

    Laverdet, G.; Le Bras, G.; Mellouki, A.; Poulet, G.

    1990-09-01

    The absolute determination of the rate constant for the reaction Br+HO 2→HBr+O 2 has been done at 298 K using the discharge-flor EPR method. The value k1 = (1.5±0.2) × 10 -12 cm 3 molecule -1 s -1 was obtained. Previous indirect measurements of k1 from a discharge-flow, LIF/mass spectrometric study of the Br/H 2CO/O 2 system have been reinterpreted, leading to values for k1 ranging from 1.0 × 10 -12 to 2.2 × 10 -12 cm 3 molecule -1 s -1 at 298 K. These results are discussed and compared with other literature values.

  2. Superfluid helium leak sealant study

    NASA Technical Reports Server (NTRS)

    Vorreiter, J. W.

    1981-01-01

    Twenty-one leak specimens were fabricated in the ends of stainless steel and aluminum tubes. Eighteen of these tubes were coated with a copolymer material to seal the leak. The other three specimens were left uncoated and served as control specimens. All 21 tubes were cold shocked in liquid helium 50 times and then the leak rate was measured while the tubes were submerged in superfluid helium at 1.7 K. During the cold shocks two of the coated specimens were mechanically damaged and eliminated from the test program. Of the remaining 16 coated specimens one suffered a total coating failure and resulting high leak rate. Another three of the coated specimens suffered partial coating failures. The leak rates of the uncoated specimens were also measured and reported. The significance of various leak rates is discussed in view of the infrared astronomical satellite (IRAS) Dewar performance.

  3. Subjective evaluation of HDTV stereoscopic videos in IPTV scenarios using absolute category rating

    NASA Astrophysics Data System (ADS)

    Wang, K.; Barkowsky, M.; Cousseau, R.; Brunnström, K.; Olsson, R.; Le Callet, P.; Sjöström, M.

    2011-03-01

    Broadcasting of high definition (HD) stereobased 3D (S3D) TV are planned, or has already begun, in Europe, the US, and Japan. Specific data processing operations such as compression and temporal and spatial resampling are commonly used tools for saving network bandwidth when IPTV is the distribution form, as this results in more efficient recording and transmission of 3DTV signals, however at the same time it inevitably brings quality degradations to the processed video. This paper investigated observers quality judgments of state of the art video coding schemes (simulcast H.264/AVC or H.264/MVC), with or without added temporal and spatial resolution reduction of S3D videos, by subjective experiments using the Absolute Category Rating method (ACR) method. The results showed that a certain spatial resolution reduction working together with high quality video compressing was the most bandwidth efficient way of processing video data when the required video quality is to be judged as "good" quality. As the subjective experiment was performed in two different laboratories in two different countries in parallel, a detailed analysis of the interlab differences was performed.

  4. Sensitivities of Soap Solutions in Leak Detection

    NASA Technical Reports Server (NTRS)

    Stuck, D.; Lam, D. Q.; Daniels, C.

    1985-01-01

    Document describes method for determining minimum leak rate to which soap-solution leak detectors sensitive. Bubbles formed at smaller leak rates than previously assumed. In addition to presenting test results, document discusses effects of joint-flange configurations, properties of soap solutions, and correlation of test results with earlier data.

  5. Simultaneous estimation of lithospheric uplift rates and absolute sea level change in southwest Scandinavia from inversion of sea level data

    NASA Astrophysics Data System (ADS)

    Nielsen, Lars; Hansen, Jens Morten; Hede, Mikkel Ulfeldt; Clemmensen, Lars B.; Pejrup, Morten; Noe-Nygaard, Nanna

    2014-11-01

    Relative sea level curves contain coupled information about absolute sea level change and vertical lithospheric movement. Such curves may be constructed based on, for example tide gauge data for the most recent times and different types of geological data for ancient times. Correct account for vertical lithospheric movement is essential for estimation of reliable values of absolute sea level change from relative sea level data and vise versa. For modern times, estimates of vertical lithospheric movement may be constrained by data (e.g. GPS-based measurements), which are independent from the relative sea level data. Similar independent data do not exist for ancient times. The purpose of this study is to test two simple inversion approaches for simultaneous estimation of lithospheric uplift rates and absolute sea level change rates for ancient times in areas where a dense coverage of relative sea level data exists and well-constrained average lithospheric movement values are known from, for example glacial isostatic adjustment (GIA) models. The inversion approaches are tested and used for simultaneous estimation of lithospheric uplift rates and absolute sea level change rates in southwest Scandinavia from modern relative sea level data series that cover the period from 1900 to 2000. In both approaches, a priori information is required to solve the inverse problem. A priori information about the average vertical lithospheric movement in the area of interest is critical for the quality of the obtained results. The two tested inversion schemes result in estimated absolute sea level rise of ˜1.2/1.3 mm yr-1 and vertical uplift rates ranging from approximately -1.4/-1.2 mm yr-1 (subsidence) to about 5.0/5.2 mm yr-1 if an a priori value of 1 mm yr-1 is used for the vertical lithospheric movement throughout the study area. In case the studied time interval is broken into two time intervals (before and after 1970), absolute sea level rise values of ˜0.8/1.2 mm yr-1 (before

  6. Preservation of the Myofascial Cuff During Posterior Fossa Surgery to Reduce the Rate of Pseudomeningocele Formation and Cerebrospinal Fluid Leak: A Technical Note

    PubMed Central

    Felbaum, Daniel R; Anaizi, Amjad; Mason, Robert B; Jean, Walter C; Voyadzis, Jean M

    2016-01-01

    Introduction: Suboccipital craniotomy is a workhorse neurosurgical operation for approaching the posterior fossa but carries a high risk of pseudomeningocele and cerebrospinal fluid (CSF) leak. We describe our experience with a simple T-shaped fascial opening that preserves the occipital myofascial cuff as compared to traditional methods to reduce this risk. Methods: A single institution, retrospective review of prospectively collected database was performed of patients that underwent a suboccipital craniectomy or craniotomy. Patient data was reviewed for craniotomy or craniectomy, dural graft, and/or sealant use as well as CSF complications. A pseudomeningocele was defined as a subcutaneous collection of cerebrospinal fluid palpable clinically and confirmed on imaging. A CSF leak was defined as a CSF-cutaneous fistula manifested by CSF leaking through the wound. All patients underwent regular postoperative visits of two weeks, one month, and three months. Results: Our retrospective review identified 33 patients matching the inclusion criteria. Overall, our cohort had a 21% (7/33) rate of clinical and radiographic pseudomeningocele formation with 9% (3/33) requiring surgical revision or a separate procedure. The rate of clinical and radiographic pseudomeningocele formation in the myofascial cuff preservation technique was less than standard techniques (12% and 31%, respectively). Revision or further surgical procedures were also reduced in the myofascial cuff preservation technique vs. the standard technique (6% vs 13%). Conclusions: Preservation of the myofascial cuff during posterior fossa surgery is a simple and adoptable technique that reduces the rate of pseudomeningocele formation and CSF leak as compared with standard techniques.   PMID:28133584

  7. Hermetic Seal Leak Detection Apparatus

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R. (Inventor)

    2013-01-01

    The present invention is a hermetic seal leak detection apparatus, which can be used to test for hermetic seal leaks in instruments and containers. A vacuum tight chamber is created around the unit being tested to minimize gas space outside of the hermetic seal. A vacuum inducing device is then used to increase the gas chamber volume inside the device, so that a slight vacuum is pulled on the unit being tested. The pressure in the unit being tested will stabilize. If the stabilized pressure reads close to a known good seal calibration, there is not a leak in the seal. If the stabilized pressure reads closer to a known bad seal calibration value, there is a leak in the seal. The speed of the plunger can be varied and by evaluating the resulting pressure change rates and final values, the leak rate/size can be accurately calculated.

  8. Mitochondrial proton leak rates in the slow, oxidative myotomal muscle and liver of the endothermic shortfin mako shark (Isurus oxyrinchus) and the ectothermic blue shark (Prionace glauca) and leopard shark (Triakis semifasciata).

    PubMed

    Duong, Cindy A; Sepulveda, Chugey A; Graham, Jeffrey B; Dickson, Kathryn A

    2006-07-01

    Mitochondrial proton leak was assessed as a potential heat source in the slow, oxidative (red) locomotor muscle and liver of the shortfin mako shark (Isurus oxyrinchus), a regional endotherm that maintains the temperature of both tissues elevated above ambient seawater temperature. We hypothesized that basal proton leak rates in red muscle and liver mitochondria of the endothermic shortfin mako shark would be greater than those of the ectothermic blue shark (Prionace glauca) and leopard shark (Triakis semifasciata). Respiration rate and membrane potential in isolated mitochondria were measured simultaneously at 20 degrees C using a Clark-type oxygen electrode and a lipophilic probe (triphenylmethylphosphonium, TPMP(+)). Succinate-stimulated respiration was titrated with inhibitors of the electron transport chain, and the non-linear relationship between respiration rate and membrane potential was quantified. Mitochondrial densities of both tissues were measured by applying the point-contact method to electron micrographs so that proton leak activity of the entire tissue could be assessed. In all three shark species, proton leak occurred at a higher rate in red muscle mitochondria than in liver mitochondria. For each tissue, the proton leak curves of the three species overlapped and, at a membrane potential of 160 mV, mitochondrial proton leak rate (nmol H(+) min(-1) mg(-1) protein) did not differ significantly between the endothermic and ectothermic sharks. This finding indicates that red muscle and liver mitochondria of the shortfin mako shark are not specialized for thermogenesis by having a higher proton conductance. However, mako mitochondria did have higher succinate-stimulated respiration rates and membrane potentials than those of the two ectothermic sharks. This means that under in vivo conditions mitochondrial proton leak rates may be higher in the mako than in the ectothermic species, due to greater electron transport activity and a larger proton gradient

  9. Determination of mantle upwelling rate beneath Taiyuan basin by using absolute gravity, GPS, groundwater and GLDAS data

    NASA Astrophysics Data System (ADS)

    Xing, Lelin; Wang, Linhai; Hu, Minzhang

    2017-03-01

    The Taiyuan basin is in the Shanxi rift system of China. Results of tectonic studies indicate that the Moho is uplifted by 2-3 km under the Taiyuan basin. However, there is no quantitative evidence showing whether the rift is still in the status of mantle upwelling. Herein, we estimated mantle upwelling rate of Taiyuan basin by using absolute gravity, GPS, groundwater and GLDAS data in this paper. In order to utilize the absolute gravity measurements in terms of tectonic study it is necessary to reduce all disturbing environmental effects. Many of those can be modeled, such as tide, polar motion, ocean tidal loading and atmospheric mass components. The Taiyuan station located in the Taiyuan basin, and absolute gravity measurements with a FG5 instrument were performed from 2009 to 2014, a secular trend was obtained. In-situ GPS data was used to estimate the vertical motion rate since 2011, and the result indicated a land subsidence. In-situ groundwater level was collected with daily surveys from 2009 to 2015, and local hydrology impact on effect was made. The global terrestrial water storage loading effect on gravity at Taiyuan station was computed by using GLDAS global hydrology model. Furthermore there is a good agreement between GRACE results and GLDAS hydrological model results. Subtracting the gravity change rate attributable to the land subsidence, groundwater level and global hydrology from the absolute gravity change rate, the residual gravity change rate was obtained. It reflects mantle upwelling about 2.1 ± 2.6 cm/yr beneath Taiyuan basin.

  10. Aerospace Payloads Leak Test Methodology

    NASA Technical Reports Server (NTRS)

    Lvovsky, Oleg; Grayson, Cynthia M.

    2010-01-01

    Pressurized and sealed aerospace payloads can leak on orbit. When dealing with toxic or hazardous materials, requirements for fluid and gas leakage rates have to be properly established, and most importantly, reliably verified using the best Nondestructive Test (NDT) method available. Such verification can be implemented through application of various leak test methods that will be the subject of this paper, with a purpose to show what approach to payload leakage rate requirement verification is taken by the National Aeronautics and Space Administration (NASA). The scope of this paper will be mostly a detailed description of 14 leak test methods recommended.

  11. Absolute rate constant of the reaction between chlorine /2P/ atoms and hydrogen peroxide from 298 to 424 K

    NASA Technical Reports Server (NTRS)

    Keyser, L. F.

    1980-01-01

    The absolute rate constant of the reaction between chlorine (2P) atoms and hydrogen peroxide was determined from 298 to 424 K, using the discharge flow resonance fluorescence technique. Pseudo-first-order conditions were used with hydrogen peroxide in large excess. A fast flow-sampling procedure limited hydrogen peroxide decomposition to less than 5% over the temperature range studied. At 298 K, the rate constant is (4.1 plus or minus 0.2) x 10 to the minus 13th cu cm/molecule-sec.

  12. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  13. Pressure dependence of the absolute rate constant for the reaction OH + C2H2 from 228 to 413 K

    NASA Technical Reports Server (NTRS)

    Michael, J. V.; Nava, D. F.; Payne, W. A.; Stief, L. J.; Borkowski, R. P.

    1980-01-01

    The pressure dependence of the absolute rate constant for the reaction of the hydroxyl radical with acetylene, important in both atmospheric and combustion chemistry, is determined for temperatures between 228 and 413 K. The flash photolysis-resonance fluorescence technique was employed at five temperatures over wide ranges of pressure and acetylene concentrations, with the OH produced by water photolysis and hydroxyl resonance fluorescent photons measured by multiscaling techniques. Results indicate that, except at the lowest temperature, the bimolecular rate constant for the reaction depends strongly on total pressure, with the pressure effect becoming more pronounced with increasing temperature. At limiting high pressures, the rate constant is found to be equal to 6.83 + or - 1.19 x 10 to the -12th exp (-646 + or - 47/T) cu cm/molecule per sec, where T is the temperature. Results thus demonstrate the importance of environmental conditions in theoretical studies of atmospheric and combustion product compositions

  14. Absolute rate parameters for the reaction of ground state atomic oxygen with carbonyl sulfide

    NASA Technical Reports Server (NTRS)

    Klemm, R. B.; Stief, L. J.

    1974-01-01

    The rate parameters for the reaction of O(3P) with carbonyl sulfide, O(3P) + OCS yields CO + SO, have been determined directly by monitoring O(3P) using the flash photolysis-resonance fluorescence technique. The value for reaction rate was measured over a temperature range of 263-502 K and the data were fitted to an Arrhenius expression with good linearity. A comparison of the present results with those from previous studies of this reaction is also presented.

  15. Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

    PubMed Central

    Gurley, Katelyn; Shang, Yu

    2012-01-01

    Abstract. This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (V˙O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and V˙O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (rV˙O2). The rBF and rV˙O2 signals were calibrated with absolute baseline BF and V˙O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology. PMID:22894482

  16. Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

    NASA Astrophysics Data System (ADS)

    Gurley, Katelyn; Shang, Yu; Yu, Guoqiang

    2012-07-01

    This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (\\Vdot O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and \\Vdot O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (r\\Vdot O2). The rBF and r\\Vdot O2 signals were calibrated with absolute baseline BF and \\Vdot O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology.

  17. Absolute rate coefficients for photorecombination of beryllium-like and boron-like silicon ions

    NASA Astrophysics Data System (ADS)

    Bernhardt, D.; Becker, A.; Brandau, C.; Grieser, M.; Hahn, M.; Krantz, C.; Lestinsky, M.; Novotný, O.; Repnow, R.; Savin, D. W.; Spruck, K.; Wolf, A.; Müller, A.; Schippers, S.

    2016-04-01

    We report measured rate coefficients for electron-ion recombination of Si10+ forming Si9+ and of Si9+ forming Si8+, respectively. The measurements were performed using the electron-ion merged-beams technique at a heavy-ion storage ring. Electron-ion collision energies ranged from 0 to 50 eV for Si9+ and from 0 to 2000 eV for Si10+, thus, extending previous measurements for Si10+ (Orban et al 2010 Astrophys. J. 721 1603) to much higher energies. Experimentally derived rate coefficients for the recombination of Si9+ and Si10+ ions in a plasma are presented along with simple parameterizations. These rate coefficients are useful for the modeling of the charge balance of silicon in photoionized plasmas (Si9+ and Si10+) and in collisionally ionized plasmas (Si10+ only). In the corresponding temperature ranges, the experimentally derived rate coefficients agree with the latest corresponding theoretical results within the experimental uncertainties.

  18. Absolute depth-dose-rate measurements for an 192Ir HDR brachytherapy source in water using MOSFET detectors.

    PubMed

    Zilio, Valéry Olivier; Joneja, Om Parkash; Popowski, Youri; Rosenfeld, Anatoly; Chawla, Rakesh

    2006-06-01

    Reported MOSFET measurements concern mostly external radiotherapy and in vivo dosimetry. In this paper, we apply the technique for absolute dosimetry in the context of HDR brachytherapy using an 192Ir source. Measured radial dose rate distributions in water for different planes perpendicular to the source axis are presented and special attention is paid to the calibration of the R and K type detectors, and to the determination of appropriate correction factors for the sensitivity variation with the increase of the threshold voltage and the energy dependence. The experimental results are compared with Monte Carlo simulated dose rate distributions. The experimental results show a good agreement with the Monte Carlo simulations: the discrepancy between experimental and Monte Carlo results being within 5% for 82% of the points and within 10% for 95% of the points. Moreover, all points except two are found to lie within the experimental uncertainties, confirming thereby the quality of the results obtained.

  19. Absolute rate constants for the reaction of atomic hydrogen with ketene from 298 to 500 K

    NASA Technical Reports Server (NTRS)

    Michael, J. V.; Nava, D. F.; Payne, W. A.; Stief, L. J.

    1979-01-01

    Rate constants for the reaction of atomic hydrogen with ketene have been measured at room temperature by two techniques, flash photolysis-resonance fluorescence and discharge flow-resonance fluorescence. The measured values are (6.19 + or - 1.68) x 10 to the -14th and (7.3 + or - 1.3) x 10 to the -14th cu cm/molecule/s, respectively. In addition, rate constants as a function of temperature have been measured over the range 298-500 K using the FP-RF technique. The results are best represented by the Arrhenius expression k = (1.88 + or - 1.12) x 10 to the -11th exp(-1725 + or - 190/T) cu cm/molecule/s, where the indicated errors are at the two standard deviation level.

  20. Absolute rate of the reaction of bromine atoms with ozone from 200 to 360 K

    NASA Technical Reports Server (NTRS)

    Michael, J. V.; Lee, J. H.; Payne, W. A.; Stief, L. J.

    1978-01-01

    The rate constant for the reaction Br + O3 yields BrO + O2 has been measured from 200 to 360 K by the technique of flash photolysis coupled to time resolved detection of bromine atoms by resonance fluorescence (FP-RF). Br atoms were produced by the flash photolysis of CH3Br at a wavelength of 165 nm. O3 concentration was monitored continuously under reaction conditions by absorption at 253.7 nm. At each of five temperatures the results were independent of substantial variations in O3 concentration, total pressure (Ar), and limited variations in flash intensity (i.e., initial Br concentration). The measured rate constants obey the Arrhenius expression, k = (7.74 plus or minus 0.50) x 10 to the -12th exp(-603 plus or minus 16/T) cu cm/molecule/sec, where the error quoted is two standard deviations.

  1. Absolute rate constant for the O plus NO chemiluminescence in the near infrared

    NASA Technical Reports Server (NTRS)

    Golde, M. F.; Roche, A. E.; Kaufman, F.

    1973-01-01

    Infrared chemiluminescence from the process O + NO (+M) NO2 + hv (+M) has been studied between 1.3 and 4.1 micrometer. The wavelength dependence of the continuum between 1.3 and 3.3 micrometer is in fair agreement with previous studies and the measured radiative rate constant at 1.51 micrometer establishes the NO-O glow in this spectral range as a secondary emission standard. Comparison with previous studies of the visible region of the glow implies that the overall radiative rate constant lies in the range (9.4 to 11.2) x 10 to the minus 17 power cu cm sec/1. In the region 3.3 to 4.1 micrometer, the previously observed broad band, peaking at 3.7 micrometer, shows a complex kinetic dependence on O and M.

  2. Absolute rate constants of alkoxyl radical reactions in aqueous solution. [Tert-butyl hydroperoxide

    SciTech Connect

    Erben-Russ, M.; Michel, C.; Bors, W.; Saran, M.

    1987-04-23

    The pulse radiolysis technique was used to generate the alkoxyl radical derived from tert-butyl hydroperoxide (/sup t/BuOOH) in aqueous solution. The reactions of this radical with 2,2'-azinobis(3-ethyl-6-benzothiazolinesulfonate) (ABTS) and promethazine were monitored by kinetic spectroscopy. The unimolecular decay rate constant of the tert-butoxyl radical (/sup t/BuO) was determined to be 1.4 x 10/sup 6/ s/sup -1/. On the basis of this value, the rate constants for /sup t/BuO attack on quercetin, crocin, crocetin, ascorbate, isoascorbate, trolox c, glutathione, thymidine, adenosine, guanosine, and unsaturated fatty acids were determined. In addition, the reaction of /sup t/BuO with the polyunsaturated fatty acids (PUFA) was observed by directly monitoring the formation of the fatty acid pentadienyl radicals. Interestingly, the attack of /sup t/BuO on PUFA was found to be faster by about one order of magnitude as compared to the same reaction in a nonpolar solvent.

  3. Leak detection capability in CANDU reactors

    SciTech Connect

    Azer, N.; Barber, D.H.; Boucher, P.J.

    1997-04-01

    This paper addresses the moisture leak detection capability of Ontario Hydro CANDU reactors which has been demonstrated by performing tests on the reactor. The tests confirmed the response of the annulus gas system (AGS) to the presence of moisture injected to simulate a pressure tube leak and also confirmed the dew point response assumed in leak before break assessments. The tests were performed on Bruce A Unit 4 by injecting known and controlled rates of heavy water vapor. To avoid condensation during test conditions, the amount of moisture which could be injected was small (2-3.5 g/hr). The test response demonstrated that the AGS is capable of detecting and annunciating small leaks. Thus confidence is provided that it would alarm for a growing pressure tube leak where the leak rate is expected to increase to kg/hr rapidly. The measured dew point response was close to that predicted by analysis.

  4. Long-life leak standard assembly

    DOEpatents

    Basford, James A.; Mathis, John E.; Wright, Harlan C.

    1982-01-01

    The present invention is directed to a portable leak standard assembly which is capable of providing a stream of high-purity reference gas at a virtually constant flow rate over an extensive period of time. The leak assembly comprises a high pressure reservoir coupled to a metal leak valve through a valve-controlled conduit. A reproducible leak valve useful in this assembly is provided by a metal tube crimped with a selected pressure loading for forming an orifice in the tube with this orifice being of a sufficient size to provide the selected flow rate. The leak valve assembly is formed of metal so that it can be "baked-out" in a vacuum furnace to rid the reservoir and attendent components of volatile impurities which reduce the efficiency of the leak standard.

  5. Temperature and pressure dependence of the absolute rate constant for the reactions of NH2 radicals with acetylene and ethylene

    NASA Technical Reports Server (NTRS)

    Bosco, S. R.; Nava, D. F.; Brobst, W. D.; Stief, L. J.

    1984-01-01

    The absolute rate constants for the reaction between the NH2 free radical and acetylene and ethylene is measured experimentally using a flash photolysis technique. The constant is considered to be a function of temperature and pressure. At each temperature level of the experiment, the observed pseudo-first-order rate constants were assumed to be independent of flash intensity. The results of the experiment indicate that the bimolecular rate constant for the NH2 + C2H2 reaction increases with pressure at 373 K and 459 K but not at lower temperatures. Results near the pressure limit conform to an Arrhenius expression of 1.11 (+ or -) 0.36 x 10 to the -13th over the temperature range from 241 to 459 K. For the reaction NH2 + C2H4, a smaller rate of increase in the bimolecular rate constant was observed over the temperature range 250-465 K. The implications of these results for current theoretical models of NH2 + C2H2 (or H4) reactions in the atmospheres of Jupiter and Saturn are discussed.

  6. Solid-state track recorder dosimetry device to measure absolute reaction rates and neutron fluence as a function of time

    DOEpatents

    Gold, Raymond; Roberts, James H.

    1989-01-01

    A solid state track recording type dosimeter is disclosed to measure the time dependence of the absolute fission rates of nuclides or neutron fluence over a period of time. In a primary species an inner recording drum is rotatably contained within an exterior housing drum that defines a series of collimating slit apertures overlying windows defined in the stationary drum through which radiation can enter. Film type solid state track recorders are positioned circumferentially about the surface of the internal recording drum to record such radiation or its secondary products during relative rotation of the two elements. In another species both the recording element and the aperture element assume the configuration of adjacent disks. Based on slit size of apertures and relative rotational velocity of the inner drum, radiation parameters within a test area may be measured as a function of time and spectra deduced therefrom.

  7. Sealing Nitrogen Tetroxide Leaks

    NASA Technical Reports Server (NTRS)

    Garrard, George G.; Houston, Donald W.; Scott, Frank D.

    1990-01-01

    Use of Furmanite FSC-N-6B sealant in clam-shell sealing device makes it possible to stop leaks of nitrogen tetroxide through defective or improperly-seated plumbing fittings. Devised to stop leaks in vent line of small rocket motor on Space Shuttle. Also used on plumbing containing hydrazine and other hazardous fluids, and repair withstands severe temperature, vibration, and shock. Leaks stopped in place, without draining or replacement of leaking parts.

  8. Measuring Small Leak Holes

    NASA Technical Reports Server (NTRS)

    Koch, D. E.; Stephenson, J. G.

    1983-01-01

    Hole sizes deduced from pressure measurements. Measuring apparatus consists of pitot tube attached to water-filled manometer. Compartment tested is pressurized with air. Pitot probe placed at known distance from leak. Dynamic pressure of jet measured at that point and static pressure measured in compartment. Useful in situations in which small leaks are tolerable but large leaks are not.

  9. Leak detector uses ultrasonics

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Iceland, W. F.; Keir, A. R.

    1978-01-01

    Probe located on outer wall of vacuum-jacketed fluid lines detects leaks on inner wall. Probe picks up and amplifies vibrations that occur when gas rushes through leak and converts them to audible signal or CRT display. System is considerably simpler to use than helium leak detectors and allows rapid checks to be made as part of routine maintenance.

  10. A rare gas optics-free absolute photon flux and energy analyzer to provide absolute photoionization rates of inflowing interstellar neutrals

    NASA Technical Reports Server (NTRS)

    Judge, Darrell L.

    1994-01-01

    A prototype spectrometer has been developed for space applications requiring long term absolute EUV photon flux measurements. The energy spectrum of the incoming photons is transformed directly into an electron energy spectrum by taking advantage of the photoelectric effect in one of several rare gases at low pressures. Using an electron energy spectrometer, followed by an electron multiplier detector, pulses due to individual electrons are counted. The overall efficiency of this process can be made essentially independent of gain drifts in the signal path, and the secular degradation of optical components which is often a problem in other techniques is avoided. A very important feature of this approach is its freedom from the problem of overlapping spectral orders that plagues grating EUV spectrometers. An instrument with these features has not been flown before, but is essential to further advances in our understanding of solar EUV flux dynamics, and the coupled dynamics of terrestrial and planetary atmospheres. The detailed characteristics of this optics-free spectrometer are presented in the publications section.

  11. Pressure dependence of the absolute rate constant for the reaction OH + C2H2 from 228 to 413K

    NASA Technical Reports Server (NTRS)

    Michael, J. V.; Nava, D. F.; Borokowski, R. P.; Payne, W. A.; Stief, L. J.

    1980-01-01

    The pressure dependence of absolute rate constants for the reaction of OH + C2H2 yields products has been examined at five temperatures ranging from 228 to 413 K. The experimental techniques which was used is flash photolysis-resonance fluoresence. OH was produced by water photolysis and hydroxyl resonance fluorescent photons were measured by multiscaling techniques. The results indicate that the low pressure bimolecular rate constant is 4 x 10 the the minus 13th power cu cm molecule (-1) s(-1) over the temperature range studied. A substantial increase in the bimolecular rate constant with an increase in pressure was observed at all temperatures except 228 K. This indicates the importance of initial adduct formation and subsequent stablization. The high pressure results are well represented by the Arrhenius expression (k sub bi) sub infinity = (6.83 + or - 1.19) x 10 to the minus 12th power exp(-646 + or - 47/T)cu cm molecule (-1) s(-1). The results are compared to previous investigated and are theoretically discussed. The implications of these results on modeling of terrestrial and planetary atmospheres and also in combustion chemistry are discussed.

  12. The reaction H + C4H2 - Absolute rate constant measurement and implication for atmospheric modeling of Titan

    NASA Technical Reports Server (NTRS)

    Nava, D. F.; Mitchell, M. B.; Stief, L. J.

    1986-01-01

    The absolute rate constant for the reaction H + C4H2 has been measured over the temperature (T) interval 210-423 K, using the technique of flash photolysis-resonance fluorescence. At each of the five temperatures employed, the results were independent of variations in C4H2 concentration, total pressure of Ar or N2, and flash intensity (i.e., the initial H concentration). The rate constant, k, was found to be equal to 1.39 x 10 to the -10th exp (-1184/T) cu cm/s, with an error of one standard deviation. The Arrhenius parameters at the high pressure limit determined here for the H + C4H2 reaction are consistent with those for the corresponding reactions of H with C2H2 and C3H4. Implications of the kinetic carbon chemistry results, particularly those at low temperature, are considered for models of the atmospheric carbon chemistry of Titan. The rate of this reaction, relative to that of the analogous, but slower, reaction of H + C2H2, appears to make H + C4H2 a very feasible reaction pathway for effective conversion of H atoms to molecular hydrogen in the stratosphere of Titan.

  13. The reaction H + C4H2 - Absolute rate constant measurement and implication for atmospheric modeling of Titan

    NASA Astrophysics Data System (ADS)

    Nava, D. F.; Mitchell, M. B.; Stief, L. J.

    1986-04-01

    The absolute rate constant for the reaction H + C4H2 has been measured over the temperature (T) interval 210-423 K, using the technique of flash photolysis-resonance fluorescence. At each of the five temperatures employed, the results were independent of variations in C4H2 concentration, total pressure of Ar or N2, and flash intensity (i.e., the initial H concentration). The rate constant, k, was found to be equal to 1.39 x 10 to the -10th exp (-1184/T) cu cm/s, with an error of one standard deviation. The Arrhenius parameters at the high pressure limit determined here for the H + C4H2 reaction are consistent with those for the corresponding reactions of H with C2H2 and C3H4. Implications of the kinetic carbon chemistry results, particularly those at low temperature, are considered for models of the atmospheric carbon chemistry of Titan. The rate of this reaction, relative to that of the analogous, but slower, reaction of H + C2H2, appears to make H + C4H2 a very feasible reaction pathway for effective conversion of H atoms to molecular hydrogen in the stratosphere of Titan.

  14. 40 CFR 86.328-79 - Leak checks.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... checks. (a) Vacuum side leak check. (1) Any location within the analysis system where a vacuum leak could affect the test results must be checked. (2) The maximum allowable leakage rate on the vacuum side is...

  15. 40 CFR 86.328-79 - Leak checks.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... checks. (a) Vacuum side leak check. (1) Any location within the analysis system where a vacuum leak could affect the test results must be checked. (2) The maximum allowable leakage rate on the vacuum side is...

  16. Measuring Pinhole Leaks - A Novel Method

    NASA Technical Reports Server (NTRS)

    Dunn, Carol Anne

    2009-01-01

    Both of the shuttle pads have one of these large liquid hydrogen tanks and the Shuttle program is currently using both pads. However, just recently, there has been increasing concerns over possible air leaks from the outside into the evacuated region. A method to detect leaks involving measuring the change in the boil-off rate of the liquid hydrogen in the tank.

  17. Detecting Methane Leaks

    NASA Technical Reports Server (NTRS)

    Grant, W. B.; Hinkley, E. D.

    1984-01-01

    Remote sensor uses laser radiation backscattered from natural targets. He/Ne Laser System for remote scanning of Methane leaks employs topographic target to scatter light to receiver near laser transmitter. Apparatus powered by 1.5kW generator transported to field sites and pointed at suspected methane leaks. Used for remote detection of natural-gas leaks and locating methane emissions in landfill sites.

  18. Propelling Charge Container Leak Rate

    DTIC Science & Technology

    1979-08-01

    effective leakage hole size for the total population of 349 containers does not exceed 1.2 mils. L 4 5Based upon the work of Somerville as reported...1977. 4. Paul N. Somerville , Tables for Obtaining Non-rarametric Tolerance Limits, Annals of Mathematical Statistics, Vol 29, Nc,. 2, pp 5991- 601, June...1958. 5. Mary Natrella, "Engineering design Handbook, Experimental Statistics," SEction 5, Tables. US Army Materiel rommand, AMCP 706-114, July 1963

  19. Apparatus for detecting leaks

    DOEpatents

    Booth, Eugene T.

    1976-02-24

    A method and apparatus for determining the position of and estimating the size of leaks in an evacuating apparatus comprising the use of a testing gas such as helium or hydrogen flowing around said apparatus whereby the testing gas will be drawn in at the site of any leaks.

  20. Leak detection aid

    DOEpatents

    Steeper, T.J.

    1989-12-26

    A leak detection apparatus and method for detecting leaks across an O-ring sealing a flanged surface to a mating surface is an improvement in a flanged surface comprising a shallow groove following O-ring in communication with an entrance and exit port intersecting the shallow groove for injecting and withdrawing, respectively, a leak detection fluid, such as helium. A small quantity of helium injected into the entrance port will flow to the shallow groove, past the O-ring and to the exit port. 2 figs.

  1. Leak detection aid

    DOEpatents

    Steeper, Timothy J.

    1989-01-01

    A leak detection apparatus and method for detecting leaks across an O-ring sealing a flanged surface to a mating surface is an improvement in a flanged surface comprising a shallow groove following O-ring in communication with an entrance and exit port intersecting the shallow groove for injecting and withdrawing, respectively, a leak detection fluid, such as helium. A small quantity of helium injected into the entrance port will flow to the shallow groove, past the O-ring and to the exit port.

  2. Blind Leak Detection for Closed Systems

    NASA Technical Reports Server (NTRS)

    Oelgoetz, Peter; Johnson, Ricky; Todd, Douglas; Russell, Samuel; Walker, James

    2003-01-01

    exact leak source position to within a very small axial distance. Many of the factors that influence the inspectability of the nozzle are addressed; including pressure rate, peak pressure, gas type, ambient temperature and surface preparation. Other applications for this thermographic inspection system are the Reinforced-Carbon-Carbon (RCC) leading edge of the Space Shuttle orbiter and braze joint integrity.

  3. Non-zero basal oxygen flow a hazard to anesthesia breathing circuit leak test.

    PubMed

    Tokumine, Joho; Sugahara, Kazuhiro; Gushiken, Kouji; Ohta, Minoru; Matsuyama, Tomoaki; Saikawa, Satoko

    2005-04-01

    The non-zero basal flow (BF) of oxygen in anesthesia machines has been set to supply the basal metabolic requirement of oxygen. However, there is no scientific evidence of its necessity. In this study we sought to clarify whether non-zero BF affects leak detection during preanesthetic inspections. Twenty-five participants performed leak tests on anesthesia machines to detect breathing circuit leaks. Artificial leak-producing devices were used to create leaks from 0 to 1.0 L/min. The investigator randomly chose the leak device and connected it into the breathing circuit. Participants, blinded as to the presence or the type of leak producing device, then tested the breathing circuit for leaks. The conventional breathing system leak test was performed with and without BF. The results of leak detection in each leak procedure were analyzed statistically. The leak detection rate of leak test with BF was less than without BF (P < 0.01). We demonstrated that non-zero BF of oxygen decreases the leak detection rate and is an obstacle for leak detection, especially for small leaks. Therefore, we recommend that breathing circuit leak tests should be performed in the absence of BF of oxygen.

  4. Gaseous leak detector

    DOEpatents

    Juravic, Jr., Frank E.

    1988-01-01

    In a short path length mass-spectrometer type of helium leak detector wherein the helium trace gas is ionized, accelerated and deflected onto a particle counter, an arrangement is provided for converting the detector to neon leak detection. The magnetic field of the deflection system is lowered so as to bring the non linear fringe area of the magnetic field across the ion path, thereby increasing the amount of deflection of the heavier neon ions.

  5. Improved gaseous leak detector

    DOEpatents

    Juravic, F.E. Jr.

    1983-10-06

    In a short path length mass-spectrometer type of helium leak detector wherein the helium trace gas is ionized, accelerated and deflected onto a particle counter, an arrangement is provided for converting the detector to neon leak detection. The magnetic field of the deflection system is lowered so as to bring the nonlinear fringe area of the magnetic field across the ion path, thereby increasing the amount of deflection of the heavier neon ions.

  6. Fractional rate of change of swim-bladder volume is reliably related to absolute depth during vertical displacements in teleost fish.

    PubMed

    Taylor, Graham K; Holbrook, Robert Iain; de Perera, Theresa Burt

    2010-09-06

    Fish must orient in three dimensions as they navigate through space, but it is unknown whether they are assisted by a sense of depth. In principle, depth can be estimated directly from hydrostatic pressure, but although teleost fish are exquisitely sensitive to changes in pressure, they appear unable to measure absolute pressure. Teleosts sense changes in pressure via changes in the volume of their gas-filled swim-bladder, but because the amount of gas it contains is varied to regulate buoyancy, this cannot act as a long-term steady reference for inferring absolute pressure. In consequence, it is generally thought that teleosts are unable to sense depth using hydrostatic pressure. Here, we overturn this received wisdom by showing from a theoretical physical perspective that absolute depth could be estimated during fast, steady vertical displacements by combining a measurement of vertical speed with a measurement of the fractional rate of change of swim-bladder volume. This mechanism works even if the amount of gas in the swim-bladder varies, provided that this variation occurs over much longer time scales than changes in volume during displacements. There is therefore no a priori physical justification for assuming that teleost fish cannot sense absolute depth by using hydrostatic pressure cues.

  7. DETECTION OF INTERSTATE LIQUIDS PIPELINE LEAKS: FEASIBILITY EVALUATION.

    SciTech Connect

    DIETZ,R.N.

    1998-10-20

    The approximately 200,000-mile fuel pipeline system in the U.S. operates at flow rates up to 2.5 x 10{sup 6}gallons per hour (GPH). Most commercial technologies only provide on-line leak detection at about 0.3% of flow rate, i.e., about 7,500 GPH or larger. Detection of leaks at about 1 GPH or so is desirable both from a regulatory and leak-prevention standpoint. Brookhaven's commercially-accepted perfluorocarbon tracer (PFT) technology for underground leak detection of utility industry dielectric fluids at leak rates less than 0.1 GPH, with new enhancements, will be able to cost-effectively detect fuel pipeline system leaks to about 1 GPH--3 orders-of-magnitude better than any on-line system. The magnitude of detected leaks would be calculable as well. Proposed mobile surveys (such as those used periodically in the gas pipeline industry) at about 110 to 120 miles per day would allow such small leaks to be detected at 10-ppb tagging levels (less than $1,500 of PFT for a 48-hour tag at the maximum transport rate) under worst-case meteorological dispersion conditions. Smaller leaks could be detected by proportionately larger tagging concentrations. Leaks would be pinpointed by subsequent conventional barholing and vapor analyses. There are no health nor safety issues associated with the use of the proposed technological approach nor any consequential environmental impacts associated with the proposed magnitudes of PFT tagging.

  8. Detection of interstate liquids pipeline leaks: Feasibility evaluation

    SciTech Connect

    Dietz, R.N.; Senum, G.I.

    1998-10-20

    The approximately 200,000-mile fuel pipeline system in the US operates at flow rates up to 2.5 {times} 10{sup 6} gallons per hour (GPH). Most commercial technologies only provide on-line leak detection at about 0.3% of flow rate, i.e., about 7,500 GPH or larger. Detection of leaks at about 1 GPH or so is desirable both from a regulatory and leak-prevention standpoint. Brookhaven`s commercially-accepted perfluorocarbon tracer (PFT) technology for underground leak detection of utility industry dielectric fluids at leak rates less than 0.1 GPH, with new enhancements, will be able to cost-effectively detect fuel pipeline system leaks to about 1 GPH--3 orders-of-magnitude better than any on-line system. The magnitude of detected leaks would be calculable as well. Proposed mobile surveys (such as those used periodically in the gas pipeline industry) at about 110 to 120 miles per day would allow such small leaks to be detected at 10-ppb tagging levels (less than $1,500 of PFT for a 48-hour tag at the maximum transport rate) under worst-case meteorological dispersion conditions. Smaller leaks could be detected by proportionately larger tagging concentrations. Leaks would be pinpointed by subsequent conventional barholing and vapor analyses. There are no health nor safety issues associated with the use of the proposed technological approach nor any consequential environmental impacts associated with the proposed magnitudes of PFT tagging.

  9. Single-Shell Tanks Leak Integrity Elements/ SX Farm Leak Causes and Locations - 12127

    SciTech Connect

    Girardot, Crystal; Harlow, Don; Venetz, Theodore; Washenfelder, Dennis; Johnson, Jeremy

    2012-07-01

    leak detection. In-tank parameters can include temperature of the supernatant and sludge, types of waste, and chemical determination by either transfer or sample analysis. Ex-tank information can be assembled from many sources including design media, construction conditions, technical specifications, and other sources. Five conditions may have contributed to SX Farm tank liner failure including: tank design, thermal shock, chemistry-corrosion, liner behavior (bulging), and construction temperature. Tank design did not apparently change from tank to tank for the SX Farm tanks; however, there could be many unknown variables present in the quality of materials and quality of construction. Several significant SX Farm tank design changes occurred from previous successful tank farm designs. Tank construction occurred in winter under cold conditions which could have affected the ductile to brittle transition temperature of the tanks. The SX Farm tanks received high temperature boiling waste from REDOX which challenged the tank design with rapid heat up and high temperatures. All eight of the leaking SX Farm tanks had relatively high rate of temperature rise. Supernatant removal with subsequent nitrate leaching was conducted in all but three of the eight leaking tanks prior to leaks being detected. It is possible that no one characteristic of the SX Farm tanks could in isolation from the others have resulted in failure. However, the application of so many stressors - heat up rate, high temperature, loss of corrosion protection, and tank design working jointly or serially resulted in their failure. Thermal shock coupled with the tank design, construction conditions, and nitrate leaching seem to be the overriding factors that can lead to tank liner failure. The distinction between leaking and sound SX Farm tanks seems to center on the waste types, thermal conditions, and nitrate leaching. (authors)

  10. SINGLE-SHELL TANKS LEAK INTEGRITY ELEMENTS/SX FARM LEAK CAUSES AND LOCATIONS - 12127

    SciTech Connect

    VENETZ TJ; WASHENFELDER D; JOHNSON J; GIRARDOT C

    2012-01-25

    leak detection. In-tank parameters can include temperature of the supernatant and sludge, types of waste, and chemical determination by either transfer or sample analysis. Ex-tank information can be assembled from many sources including design media, construction conditions, technical specifications, and other sources. Five conditions may have contributed to SX Farm tank liner failure including: tank design, thermal shock, chemistry-corrosion, liner behavior (bulging), and construction temperature. Tank design did not apparently change from tank to tank for the SX Farm tanks; however, there could be many unknown variables present in the quality of materials and quality of construction. Several significant SX Farm tank design changes occurred from previous successful tank farm designs. Tank construction occurred in winter under cold conditions which could have affected the ductile to brittle transition temperature of the tanks. The SX Farm tanks received high temperature boiling waste from REDOX which challenged the tank design with rapid heat up and high temperatures. All eight of the leaking SX Farm tanks had relatively high rate of temperature rise. Supernatant removal with subsequent nitrate leaching was conducted in all but three of the eight leaking tanks prior to leaks being detected. It is possible that no one characteristic of the SX Farm tanks could in isolation from the others have resulted in failure. However, the application of so many stressors - heat up rate, high temperature, loss of corrosion protection, and tank design - working jointly or serially resulted in their failure. Thermal shock coupled with the tank design, construction conditions, and nitrate leaching seem to be the overriding factors that can lead to tank liner failure. The distinction between leaking and sound SX Farm tanks seems to center on the waste types, thermal conditions, and nitrate leaching.

  11. Ammonia Leak Locator Study

    NASA Technical Reports Server (NTRS)

    Dodge, Franklin T.; Wuest, Martin P.; Deffenbaugh, Danny M.

    1995-01-01

    The thermal control system of International Space Station Alpha will use liquid ammonia as the heat exchange fluid. It is expected that small leaks (of the order perhaps of one pound of ammonia per day) may develop in the lines transporting the ammonia to the various facilities as well as in the heat exchange equipment. Such leaks must be detected and located before the supply of ammonia becomes critically low. For that reason, NASA-JSC has a program underway to evaluate instruments that can detect and locate ultra-small concentrations of ammonia in a high vacuum environment. To be useful, the instrument must be portable and small enough that an astronaut can easily handle it during extravehicular activity. An additional complication in the design of the instrument is that the environment immediately surrounding ISSA will contain small concentrations of many other gases from venting of onboard experiments as well as from other kinds of leaks. These other vapors include water, cabin air, CO2, CO, argon, N2, and ethylene glycol. Altogether, this local environment might have a pressure of the order of 10(exp -7) to 10(exp -6) torr. Southwest Research Institute (SwRI) was contracted by NASA-JSC to provide support to NASA-JSC and its prime contractors in evaluating ammonia-location instruments and to make a preliminary trade study of the advantages and limitations of potential instruments. The present effort builds upon an earlier SwRI study to evaluate ammonia leak detection instruments [Jolly and Deffenbaugh]. The objectives of the present effort include: (1) Estimate the characteristics of representative ammonia leaks; (2) Evaluate the baseline instrument in the light of the estimated ammonia leak characteristics; (3) Propose alternative instrument concepts; and (4) Conduct a trade study of the proposed alternative concepts and recommend promising instruments. The baseline leak-location instrument selected by NASA-JSC was an ion gauge.

  12. Structural effects on the beta-scission reaction of alkoxyl radicals. Direct measurement of the absolute rate constants for ring opening of benzocycloalken-1-oxyl radicals.

    PubMed

    Bietti, Massimo; Lanzalunga, Osvaldo; Salamone, Michela

    2005-02-18

    [reaction: see text] The absolute rate constants for beta-scission of a series of benzocycloalken-1-oxyl radicals and of the 2-(4-methylphenyl)-2-butoxyl radical have been measured directly by laser flash photolysis. The benzocycloalken-1-oxyl radicals undergo ring opening with rates which parallel the ring strain of the corresponding cycloalkanes. In the 1-X-indan-1-oxyl radical series, ring opening is observed when X = H, Me, whereas exclusive C-X bond cleavage occurs when X = Et. The factors governing the fragmentation regioselectivity are discussed.

  13. Glycol leak detection system

    NASA Astrophysics Data System (ADS)

    Rabe, Paul; Browne, Keith; Brink, Janus; Coetzee, Christiaan J.

    2016-07-01

    MonoEthylene glycol coolant is used extensively on the Southern African Large Telescope to cool components inside the telescope chamber. To prevent coolant leaks from causing serious damage to electronics and optics, a Glycol Leak Detection System was designed to automatically shut off valves in affected areas. After two years of research and development the use of leaf wetness sensors proved to work best and is currently operational. These sensors are placed at various critical points within the instrument payload that would trigger the leak detector controller, which closes the valves, and alerts the building management system. In this paper we describe the research of an initial concept and the final accepted implementation and the test results thereof.

  14. Determination of subjective similarity for pairs of masses and pairs of clustered microcalcifications on mammograms: Comparison of similarity ranking scores and absolute similarity ratings

    SciTech Connect

    Muramatsu, Chisako; Li Qiang; Schmidt, Robert A.; Shiraishi, Junji; Suzuki, Kenji; Newstead, Gillian M.; Doi, Kunio

    2007-07-15

    The presentation of images that are similar to that of an unknown lesion seen on a mammogram may be helpful for radiologists to correctly diagnose that lesion. For similar images to be useful, they must be quite similar from the radiologists' point of view. We have been trying to quantify the radiologists' impression of similarity for pairs of lesions and to establish a ''gold standard'' for development and evaluation of a computerized scheme for selecting such similar images. However, it is considered difficult to reliably and accurately determine similarity ratings, because they are subjective. In this study, we compared the subjective similarities obtained by two different methods, an absolute rating method and a 2-alternative forced-choice (2AFC) method, to demonstrate that reliable similarity ratings can be determined by the responses of a group of radiologists. The absolute similarity ratings were previously obtained for pairs of masses and pairs of microcalcifications from five and nine radiologists, respectively. In this study, similarity ranking scores for eight pairs of masses and eight pairs of microcalcifications were determined by use of the 2AFC method. In the first session, the eight pairs of masses and eight pairs of microcalcifications were grouped and compared separately for determining the similarity ranking scores. In the second session, another similarity ranking score was determined by use of mixed pairs, i.e., by comparison of the similarity of a mass pair with that of a calcification pair. Four pairs of masses and four pairs of microcalcifications were grouped together to create two sets of eight pairs. The average absolute similarity ratings and the average similarity ranking scores showed very good correlations in the first study (Pearson's correlation coefficients: 0.94 and 0.98 for masses and microcalcifications, respectively). Moreover, in the second study, the correlations between the absolute ratings and the ranking scores were also

  15. Absolute Zero

    NASA Astrophysics Data System (ADS)

    Donnelly, Russell J.; Sheibley, D.; Belloni, M.; Stamper-Kurn, D.; Vinen, W. F.

    2006-12-01

    Absolute Zero is a two hour PBS special attempting to bring to the general public some of the advances made in 400 years of thermodynamics. It is based on the book “Absolute Zero and the Conquest of Cold” by Tom Shachtman. Absolute Zero will call long-overdue attention to the remarkable strides that have been made in low-temperature physics, a field that has produced 27 Nobel Prizes. It will explore the ongoing interplay between science and technology through historical examples including refrigerators, ice machines, frozen foods, liquid oxygen and nitrogen as well as much colder fluids such as liquid hydrogen and liquid helium. A website has been established to promote the series: www.absolutezerocampaign.org. It contains information on the series, aimed primarily at students at the middle school level. There is a wealth of material here and we hope interested teachers will draw their student’s attention to this website and its substantial contents, which have been carefully vetted for accuracy.

  16. SEALING SIMULATED LEAKS

    SciTech Connect

    Michael A. Romano

    2004-09-01

    This report details the testing equipment, procedures and results performed under Task 7.2 Sealing Simulated Leaks. In terms of our ability to seal leaks identified in the technical topical report, Analysis of Current Field Data, we were 100% successful. In regards to maintaining seal integrity after pigging operations we achieved varying degrees of success. Internal Corrosion defects proved to be the most resistant to the effects of pigging while External Corrosion proved to be the least resistant. Overall, with limitations, pressure activated sealant technology would be a viable option under the right circumstances.

  17. Long-life leak standard assembly. [Patent application

    DOEpatents

    Basford, J.A.; Mathis, J.E.; Wright, H.C.

    1980-11-12

    The present invention is directed to a portable leak standard assembly which is capable of providing a stream of high-purity reference gas at a virtually constant flow rate over an extensive period of time. The leak assembly comprises a high pressure reservoir coupled to a metal leak valve through a valve-controlled conduit. A reproducible leak valve useful in this assembly is provided by a metal tube crimped with a selected pressure loading for forming an orifice in the tube with this orifice being of a sufficient size to provide the selected flow rate. The leak valve assembly is formed of metal so that it can be baked-out in a vacuum furnace to rid the reservoir and attendent components of volatile impurities which reduce the efficiency of the leak standard.

  18. Intrinsic absolute bioavailability prediction in rats based on in situ absorption rate constants and/or in vitro partition coefficients: 6-fluoroquinolones.

    PubMed

    Sánchez-Castaño, G; Ruíz-García, A; Bañón, N; Bermejo, M; Merino, V; Freixas, J; Garriguesx, T M; Plá-Delfina, J M

    2000-11-01

    A preliminary study attempting to predict the intrinsic absolute bioavailability of a group of antibacterial 6-fluoroquinolones-including true and imperfect homologues as well as heterologues-was carried out. The intrinsic absolute bioavailability of the test compounds, F, was assessed on permanently cannulated conscious rats by comparing the trapezoidal normalized areas under the plasma concentration-time curves obtained by intravenous and oral routes (n = 8-12). The high-performance liquid chromatography analytical methods used for plasma samples are described. Prediction of the absolute bioavailability of the compounds was based on their intrinsic rat gut in situ absorption rate constant, k(a). The working equation was: where T represents the mean absorbing time. A T value of 0.93 (+/-0.06) h provides the best correlation between predicted and experimentally obtained bioavailabilities (F' and F, respectively) when k(a) values are used (slope a = 1.10; intercept b = -0.05; r = 0.991). The k(a) values can also be expressed in function of the in vitro partition coefficients, P, between n-octanol and a phosphate buffer. In this case, theoretical k(a) values can be determined with the parameters of a standard k(a)/P correlation previously established for a group of model compounds. When P values are taken instead of k(a) values, reliable bioavailability predictions can also be made. These and other relevant features of the method are discussed.

  19. High-accuracy absolute rotation rate measurements with a large ring laser gyro: establishing the scale factor.

    PubMed

    Hurst, Robert B; Mayerbacher, Marinus; Gebauer, Andre; Schreiber, K Ulrich; Wells, Jon-Paul R

    2017-02-01

    Large ring lasers have exceeded the performance of navigational gyroscopes by several orders of magnitude and have become useful tools for geodesy. In order to apply them to tests in fundamental physics, remaining systematic errors have to be significantly reduced. We derive a modified expression for the Sagnac frequency of a square ring laser gyro under Earth rotation. The modifications include corrections for dispersion (of both the gain medium and the mirrors), for the Goos-Hänchen effect in the mirrors, and for refractive index of the gas filling the cavity. The corrections were measured and calculated for the 16  m2 Grossring laser located at the Geodetic Observatory Wettzell. The optical frequency and the free spectral range of this laser were measured, allowing unique determination of the longitudinal mode number, and measurement of the dispersion. Ultimately we find that the absolute scale factor of the gyroscope can be estimated to an accuracy of approximately 1 part in 108.

  20. Sensitive hydrogen leak detector

    DOEpatents

    Myneni, Ganapati Rao

    1999-01-01

    A sensitive hydrogen leak detector system using passivation of a stainless steel vacuum chamber for low hydrogen outgassing, a high compression ratio vacuum system, a getter operating at 77.5 K and a residual gas analyzer as a quantitative hydrogen sensor.

  1. Sensitive hydrogen leak detector

    DOEpatents

    Myneni, G.R.

    1999-08-03

    A sensitive hydrogen leak detector system is described which uses passivation of a stainless steel vacuum chamber for low hydrogen outgassing, a high compression ratio vacuum system, a getter operating at 77.5 K and a residual gas analyzer as a quantitative hydrogen sensor. 1 fig.

  2. Absolute rate of the reaction of atomic hydrogen with ethylene from 198 to 320 K at high pressure

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Michael, J. V.; Payne, W. A.; Stief, L. J.

    1978-01-01

    The rate constant for the H+C2H4 reaction has been measured as a function of temperature. Experiments were performed with high pressures of Ar heat bath gas at seven temperatures from 198 to 320 K with the flash photolysis-resonance fluorescence (FP-RF) technique. Pressures were chosen so as to isolate the addition rate constant k1. The results are well represented by an Arrhenius expression. The results are compared with other studies and are theoretically discussed.

  3. Absolute rate of the reaction of Cl(p-2) with molecular hydrogen from 200 - 500 K

    NASA Technical Reports Server (NTRS)

    Whytock, D. A.; Lee, J. H.; Michael, J. V.; Payne, W. A.; Stief, L. J.

    1976-01-01

    Rate constants for the reaction of atomic chlorine with hydrogen are measured from 200 - 500 K using the flash photolysis-resonance fluorescence technique. The results are compared with previous work and are discussed with particular reference to the equilibrium constant for the reaction and to relative rate data for chlorine atom reactions. Theoretical calculations, using the BEBO method with tunneling, give excellent agreement with experiment.

  4. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  5. The Leaking-Toilet Challenge

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2008-01-01

    Leaking toilets can cost homeowners big dollars--often before it is even realized. Homeowners do not necessarily hear it leaking. It just does, and when the water bill comes due, it can be a most unpleasant surprise. This article presents a classroom challenge to try to develop leak-detection ideas that would be inexpensive and easily added to…

  6. Margins in high temperature leak-before-break assessments

    SciTech Connect

    Budden, P.J.; Hooton, D.G.

    1997-04-01

    Developments in the defect assessment procedure R6 to include high-temperature mechanisms in Leak-before-Break arguments are described. In particular, the effect of creep on the time available to detect a leak and on the crack opening area, and hence leak rate, is discussed. The competing influence of these two effects is emphasized by an example. The application to Leak-before-Break of the time-dependent failure assessment diagram approach for high temperature defect assessment is then outlined. The approach is shown to be of use in assessing the erosion of margins by creep.

  7. Absolute rate of the reaction of C l(2P) with methane from 200-500 K

    NASA Technical Reports Server (NTRS)

    Whytock, D. A.; Lee, J. H.; Michael, J. V.; Payne, W. A.; Stief, L. J.

    1976-01-01

    Rate constants for the reaction of atomic chlorine with methane have been measured from 200-500K using the flash photolysis-resonance fluorescence technique. When the results from fourteen equally spaced experimental determinations are plotted in Arrhenius form a definite curvature is noted. The results are compared to previous work and are theoretically discussed.

  8. Absolute Photometry

    NASA Astrophysics Data System (ADS)

    Hartig, George

    1990-12-01

    The absolute sensitivity of the FOS will be determined in SV by observing 2 stars at 3 epochs, first in 3 apertures (1.0", 0.5", and 0.3" circular) and then in 1 aperture (1.0" circular). In cycle 1, one star, BD+28D4211 will be observed in the 1.0" aperture to establish the stability of the sensitivity and flat field characteristics and improve the accuracy obtained in SV. This star will also be observed through the paired apertures since these are not calibrated in SV. The stars will be observed in most detector/grating combinations. The data will be averaged to form the inverse sensitivity functions required by RSDP.

  9. Intelligent Leak Detection System

    SciTech Connect

    Mohaghegh, Shahab D.

    2014-10-27

    apability of underground carbon dioxide storage to confine and sustain injected CO2 for a very long time is the main concern for geologic CO2 sequestration. If a leakage from a geological CO2 sequestration site occurs, it is crucial to find the approximate amount and the location of the leak in order to implement proper remediation activity. An overwhelming majority of research and development for storage site monitoring has been concentrated on atmospheric, surface or near surface monitoring of the sequestered CO2. This study aims to monitor the integrity of CO2 storage at the reservoir level. This work proposes developing in-situ CO2 Monitoring and Verification technology based on the implementation of Permanent Down-hole Gauges (PDG) or “Smart Wells” along with Artificial Intelligence and Data Mining (AI&DM). The technology attempts to identify the characteristics of the CO2 leakage by de-convolving the pressure signals collected from Permanent Down-hole Gauges (PDG). Citronelle field, a saline aquifer reservoir, located in the U.S. was considered for this study. A reservoir simulation model for CO2 sequestration in the Citronelle field was developed and history matched. The presence of the PDGs were considered in the reservoir model at the injection well and an observation well. High frequency pressure data from sensors were collected based on different synthetic CO2 leakage scenarios in the model. Due to complexity of the pressure signal behaviors, a Machine Learning-based technology was introduced to build an Intelligent Leakage Detection System (ILDS). The ILDS was able to detect leakage characteristics in a short period of time (less than a day) demonstrating the capability of the system in quantifying leakage characteristics subject to complex rate behaviors. The performance of ILDS was examined under different conditions such as multiple well leakages, cap rock leakage, availability of an additional monitoring well, presence of pressure drift and noise

  10. Absolute rate constant of the reaction OH + H2O2 yields HO2 + H2O from 245 to 423 K

    NASA Technical Reports Server (NTRS)

    Keyser, L. F.

    1980-01-01

    The absolute rate constant of the reaction between the hydroxyl radical and hydrogen peroxide was measured by using the discharge-flow resonance fluorescence technique at total pressure between 1 and 4 torr. At 298 K the result is (1.64 + or - 0.32) x 10 to the -12th cu cm/molecule s. The observed rate constant is independent of pressure, surface-to-volume ratio, the addition of vibrational quenchers, and the source of OH. The temperature dependence has also been determined between 245 and 423 K; the resulting Arrhenius expression is k cu cm/molecule s is equal to (2.51 + or - 0.6) x 10 to the -12th exp(-126 + or - 76/T).

  11. Absolute rate of the reaction of O/3-P/ with hydrogen sulfide over the temperature range 263 to 495 K

    NASA Technical Reports Server (NTRS)

    Whytock, D. A.; Timmons, R. B.; Lee, J. H.; Michael, J. V.; Payne, W. A.; Stief, L. J.

    1976-01-01

    The technique of flash photolysis coupled with time resolved detection of O via resonance fluorescence has been used to obtain rate constants for the reaction of O(3-P) with H2S at temperatures from 263 to 495 K and at pressures in the range 10-400 torr. Under conditions where secondary reactions are avoided, the measured rate constants for the primary step obey the Arrhenius equation k = (7.24 plus or minus 1.07) x 10 to the -12th exp(-3300 plus or minus 100/1.987 T) cu cm/molecules/s. Experiments with D2S show that the reaction exhibits a primary isotope effect, in support of a hydrogen abstraction mechanism.

  12. Absolute rate parameters for the reaction of ground state atomic oxygen with carbonyl sulfide. [using O(3P) monitoring

    NASA Technical Reports Server (NTRS)

    Klemm, R. B.; Stief, L. J.

    1974-01-01

    The rate parameters for the reaction of O(3P) with carbonyl sulfide, O(3P) + OCS yields CO + SO have been determined directly by monitoring O(3P) using the flash photolysis-resonance fluorescence technique. The value for k sub 1 was measured over a temperature range of 263 - 502 K and the data were fitted to an Arrhenuis expression with good linearity.

  13. Improved Portable Ultrasonic Leak Detectors

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.; Moerk, John S.; Haskell, William D.; Cox, Robert B.; Polk, Jimmy D.; Strobel, James P.; Luaces, Frank

    1995-01-01

    Improved portable ultrasonic leak detector features three interchangeable ultrasonic-transducer modules, each suited for operation in unique noncontact or contact mode. One module equipped with ultrasound-collecting horn for use in scanning to detect leaks from distance; horn provides directional sensitivity pattern with sensitivity multiplied by factor of about 6 in forward direction. Another module similar, does not include horn; this module used for scanning close to suspected leak, where proximity of leak more than offsets loss of sensitivity occasioned by lack of horn. Third module designed to be pressed against leaking vessel; includes rugged stainless-steel shell. Improved detectors perform significantly better, smaller, more rugged, and greater sensitivity.

  14. Hazardous fluid leak detector

    DOEpatents

    Gray, Harold E.; McLaurin, Felder M.; Ortiz, Monico; Huth, William A.

    1996-01-01

    A device or system for monitoring for the presence of leaks from a hazardous fluid is disclosed which uses two electrodes immersed in deionized water. A gas is passed through an enclosed space in which a hazardous fluid is contained. Any fumes, vapors, etc. escaping from the containment of the hazardous fluid in the enclosed space are entrained in the gas passing through the enclosed space and transported to a closed vessel containing deionized water and two electrodes partially immersed in the deionized water. The electrodes are connected in series with a power source and a signal, whereby when a sufficient number of ions enter the water from the gas being bubbled through it (indicative of a leak), the water will begin to conduct, thereby allowing current to flow through the water from one electrode to the other electrode to complete the circuit and activate the signal.

  15. Endoscopic stenting for laparoscopic sleeve gastrectomy leaks

    PubMed Central

    Aydın, Mehmet Timuçin; Alahdab, Yeşim Özen; Aras, Orhan; Karip, Bora; Onur, Ender; İşcan, Yalın; Memişoğlu, Kemal

    2016-01-01

    Objective Laparoscopic sleeve gastrectomy is a widely accepted and effective bariatric surgery method. The rate of leakage at the staple-line has been reported to be between 1.5 and 5%. Aside from the use of percutaneous drainage, re-laparoscopy, or abdominal sepsis control by laparotomy, endoscopic esophagogastric stent placement is increasingly preferred as a treatment method. Because laparoscopic sleeve gastrectomy is a widely used modality in our hospital, we aimed to evaluate the rate of leaks and the results of stent placements in our patients. Material and Methods Between January 1st 2010 and August 31st 2014, laparoscopic sleeve gastrectomy was performed on 236 patients by three surgeons. The demographic information and postoperative discharge summaries were collected and analyzed with the permission of the hospital ethics committee. Information about leak treatment management was also collected. Results Leaks after laparoscopic sleeve gastrectomy in four patients were stented in the first postoperative month. Short (12 cm) Hanora® (M.I.Tech, Gyeonggi-do, Korea) self-expandable coated stents were placed in two patients, and long (24 cm) Hanora® self-expandable coated stents were placed in the other two. The stents were removed after one month in two patients, two and a half months later in one, and five months later in another patient. The leaks were demonstrated to be healed in all patients after stent removal. Endoscopic stent revision was performed in one patient due to migration of the stent and in another for stent breakage. Conclusion The success rate of treatment of leaks after laparoscopic sleeve gastrectomy by stent placement has been variable in the literature. The success in early stent placement has been shown to be related to physician expertise. According to the results of our patients, we suggest that endoscopic stent placement in the early stage after controlling sepsis is an effective method in the management of leaks. PMID:28149125

  16. Aspects of leak detection

    SciTech Connect

    Chivers, T.C.

    1997-04-01

    A requirement of a Leak before Break safety case is that the leakage from the through wall crack be detected prior to any growth leading to unacceptable failure. This paper sets out to review some recent developments in this field. It does not set out to be a comprehensive guide to all of the methods available. The discussion concentrates on acoustic emission and how the techniques can be qualified and deployed on operational plant.

  17. Absolute rate determinations and temperature dependences of the gas-phase reactions of O( 3P) with halogenated propenes

    NASA Astrophysics Data System (ADS)

    Cometto, Pablo M.; Teruel, Mariano A.; Taccone, Raúl A.; Lane, Silvia I.

    2006-01-01

    The rate constants for the gas-phase reactions of ground state oxygen atoms with CF 3CH dbnd CH 2 (1), CF 3CF dbnd CF 2 (2) and CF 3CCl dbnd CCl 2 (3) have been measured directly using a discharge flow tube employing the O( 3P) chemiluminescence titration method. The experiments were carried out under pseudo-first-order conditions with [O( 3P)] 0 ≪ [propene] 0. The temperature dependences of the reactions were studied for the first time in the range 298-363 K. The Arrhenius expressions obtained (in units of cm 3 molecule -1 s -1) were: k1 = (0.28 ± 0.09) × 10 -11 exp[-(10.4 ± 0.9) × 10 3/ RT], k2 = (1.57 ± 0.72) × 10 -11 exp[-(15.6 ± 1.3) × 10 3/ RT], k3 = (2.23 ± 1.27) × 10 -11 exp[-(16.0 ± 1.6) × 10 3/ RT]. All the rate coefficients display a positive temperature dependence which points to the importance of the irreversibility of the addition mechanism for these reactions. Halogen substitution in the alkenes is discussed in terms of reactivity with O( 3P) and its relation with the ionization potential.

  18. Single-Shell Tank Leak Integrity Summary

    SciTech Connect

    Harlow, D. G.; Girardot, C. L.; Venetz, T. J.

    2015-03-26

    This document summarizes and evaluates the information in the Hanford Tri-Party Agreement Interim Milestone M-045-91F Targets completed between 2010 and 2015. 1) Common factors of SST liner failures (M-045-91F-T02), 2) the feasibility of testing for ionic conductivity between the inside and outside of SSTs (M-045-91F-T03, and 3) the causes, locations, and rates of leaks from leaking SSTs (M-045-91F-T04).

  19. Absolute and relative blindsight.

    PubMed

    Balsdon, Tarryn; Azzopardi, Paul

    2015-03-01

    The concept of relative blindsight, referring to a difference in conscious awareness between conditions otherwise matched for performance, was introduced by Lau and Passingham (2006) as a way of identifying the neural correlates of consciousness (NCC) in fMRI experiments. By analogy, absolute blindsight refers to a difference between performance and awareness regardless of whether it is possible to match performance across conditions. Here, we address the question of whether relative and absolute blindsight in normal observers can be accounted for by response bias. In our replication of Lau and Passingham's experiment, the relative blindsight effect was abolished when performance was assessed by means of a bias-free 2AFC task or when the criterion for awareness was varied. Furthermore, there was no evidence of either relative or absolute blindsight when both performance and awareness were assessed with bias-free measures derived from confidence ratings using signal detection theory. This suggests that both relative and absolute blindsight in normal observers amount to no more than variations in response bias in the assessment of performance and awareness. Consideration of the properties of psychometric functions reveals a number of ways in which relative and absolute blindsight could arise trivially and elucidates a basis for the distinction between Type 1 and Type 2 blindsight.

  20. Pressure dependence of the absolute rate constant for the reaction Cl + C2H2 from 210-361 K

    NASA Technical Reports Server (NTRS)

    Brunning, J.; Stief, L. J.

    1985-01-01

    In recent years, considerable attention has been given to the role of chlorine compounds in the catalytic destruction of stratospheric ozone. However, while some reactions have been studied extensively, the kinetic data for the reaction of Cl with C2H2 is sparse with only three known determinations of the rate constant k3. The reactions involved are Cl + C2H2 yields reversibly ClC2H2(asterisk) (3a) and ClC2H2(asterisk) + M yields ClC2H2 + M (3b). In the present study, flash photolysis coupled with chlorine atomic resonance fluorescence have been employed to determine the pressure and temperature dependence of k3 with the third body M = Ar. Room temperature values are also reported for M = N2. The pressure dependence observed in the experiments confirms the expectation that the reaction involves addition of Cl to the unsaturated C2H2 molecule followed by collisional stabilization of the resulting adduct radical.

  1. Absolute rate constants for hydrogen atom transfer from tertiary amides to the cumyloxyl radical: evaluating the role of stereoelectronic effects.

    PubMed

    Salamone, Michela; Milan, Michela; DiLabio, Gino A; Bietti, Massimo

    2014-08-01

    A time-resolved kinetic study of the hydrogen atom transfer (HAT) reactions from a series of alkanamides to the cumyloxyl radical (CumO(•)) was carried out. With N,N-dialkylformamides HAT preferentially occurs from the formyl C-H bond, while in N-formylpyrrolidine HAT mostly occurs from the ring α-C-H bonds. With the acetamides and the alkanamides almost exclusive HAT from the C-H bonds that are α to nitrogen was observed. The results obtained show that alignment between the C-H bond being broken and the amide π-system can lead to significant increases in the HAT rate constant (kH). This finding points toward the important role of stereoelectronic effects on the HAT reactivity and selectivity. The highest kH values were measured for the reactions of CumO(•) with N-acylpyrrolidines. These substrates have ring α-C-H bonds that are held in a conformation that is optimally aligned with the amide π-system, thus allowing for the relatively facile HAT reaction. The lowest kH value was measured for the reaction of N,N-diisobutylacetamide, wherein the steric bulk associated with the N-isobutyl groups increases the energy barrier required to reach the most suitable conformation for HAT. The experimental results are well supported by the computed BDEs for the C-H bonds of the most representative substrates.

  2. Optically based quantification of absolute cerebral metabolic rate of oxygen (CMRO2) with high spatial resolution in rodents

    NASA Astrophysics Data System (ADS)

    Yaseen, Mohammad A.; Srinivasan, Vivek J.; Sakadžić, Sava; Vinogradov, Sergei A.; Boas, David A.

    2010-02-01

    Measuring oxygen delivery in brain tissue is important for identifying the pathophysiological changes associated with brain injury and various diseases such as cancer, stroke, and Alzheimer's disease. We have developed a multi-modal imaging system for minimally invasive measurement of cerebral oxygenation and blood flow in small animals with high spatial resolution. The system allows for simultaneous measurement of blood flow using Fourier-domain optical coherence tomography, and oxygen partial pressure (pO2) using either confocal or multiphoton phosphorescence lifetime imaging with exogenous porphyrin-based dyes sensitive to dissolved oxygen. Here we present the changes in pO2 and blood flow in superficial cortical vessels of Sprague Dawley rats in response to conditions such as hypoxia, hyperoxia, and functional stimulation. pO2 measurements display considerable heterogeneity over distances that cannot be resolved with more widely used oxygen-monitoring techniques such as BOLD-fMRI. Large increases in blood flow are observed in response to functional stimulation and hypoxia. Our system allows for quantification of cerebral metabolic rate of oxygen (CMRO2) with high spatial resolution, providing a better understanding of metabolic dynamics during functional stimulation and under various neuropathologies. Ultimately, better insight into the underlying mechanisms of neuropathologies will facilitate the development of improved therapeutic strategies to minimize damage to brain tissue.

  3. Leak test fitting

    DOEpatents

    Pickett, P.T.

    A hollow fitting for use in gas spectrometry leak testing of conduit joints is divided into two generally symmetrical halves along the axis of the conduit. A clip may quickly and easily fasten and unfasten the halves around the conduit joint under test. Each end of the fitting is sealable with a yieldable material, such as a piece of foam rubber. An orifice is provided in a wall of the fitting for the insertion or detection of helium during testing. One half of the fitting also may be employed to test joints mounted against a surface.

  4. Leak test fitting

    DOEpatents

    Pickett, Patrick T.

    1981-01-01

    A hollow fitting for use in gas spectrometry leak testing of conduit joints is divided into two generally symmetrical halves along the axis of the conduit. A clip may quickly and easily fasten and unfasten the halves around the conduit joint under test. Each end of the fitting is sealable with a yieldable material, such as a piece of foam rubber. An orifice is provided in a wall of the fitting for the insertion or detection of helium during testing. One half of the fitting also may be employed to test joints mounted against a surface.

  5. Variable leak gas source

    DOEpatents

    Henderson, Timothy M.; Wuttke, Gilbert H.

    1977-01-01

    A variable leak gas source and a method for obtaining the same which includes filling a quantity of hollow glass micro-spheres with a gas, storing said quantity in a confined chamber having a controllable outlet, heating said chamber above room temperature, and controlling the temperature of said chamber to control the quantity of gas passing out of said controllable outlet. Individual gas filled spheres may be utilized for calibration purposes by breaking a sphere having a known quantity of a known gas to calibrate a gas detection apparatus.

  6. Enhancement of farmland greenhouse gas emissions from leakage of stored CO2: simulation of leaked CO2 from CCS.

    PubMed

    Zhang, Xueyan; Ma, Xin; Wu, Yang; Li, Yue

    2015-06-15

    The effects of leaked CO2 on plant and soil constitute a key objective of carbon capture and storage (CCS) safety. The effects of leaked CO2 on trace soil gas (e.g., methane (CH4) and nitrous oxide (N2O) emissions in farmlands are not well-understood. This study simulated the effects of elevated soil CO2 on CH4 and N2O through pot experiments. The results revealed that significant increases of CH4 and N2O emissions were induced by the simulated CO2 leakages; the emission rates of CH4 and N2O were substantial, reaching about 222 and 48 times than that of the control, respectively. The absolute global warming potentials (GWPs) of the additional CH4 and N2O are considerable, but the cumulative GWPs of the additional CH4 and N2O only accounted for 0.03% and 0.06%, respectively, of the cumulative amount of leaked CO2 under high leakage conditions. The results demonstrate that leakage from CCS projects may lead to additional greenhouse gas emissions from soil; however, in general, the amount of additional CH4 and N2O emissions is negligible when compared with the amount of leaked CO2.

  7. Assessment of Remote Sensing Technologies for Location of Hydrogen and Helium Leaks

    NASA Technical Reports Server (NTRS)

    Sellar, R. Glenn; Wang, Danli

    2000-01-01

    The objective of this initial phase of this research effort is to: 1) Evaluate remote sensing technologies for location of leaks of gaseous molecular hydrogen (H2) and gaseous helium (He) in air, for space transportation applications; and 2) Develop a diffusion model that predicts concentration of H2 or He gas as a function of leak rate and distance from the leak.

  8. SSME propellant path leak detection

    NASA Technical Reports Server (NTRS)

    Crawford, Roger; Shohadaee, Ahmad Ali

    1989-01-01

    The complicated high-pressure cycle of the space shuttle main engine (SSME) propellant path provides many opportunities for external propellant path leaks while the engine is running. This mode of engine failure may be detected and analyzed with sufficient speed to save critical engine test hardware from destruction. The leaks indicate hardware failures which will damage or destroy an engine if undetected; therefore, detection of both cryogenic and hot gas leaks is the objective of this investigation. The primary objective of this phase of the investigation is the experimental validation of techniques for detecting and analyzing propellant path external leaks which have a high probability of occurring on the SSME. The selection of candidate detection methods requires a good analytic model for leak plumes which would develop from external leaks and an understanding of radiation transfer through the leak plume. One advanced propellant path leak detection technique is obtained by using state-of-the-art technology infrared (IR) thermal imaging systems combined with computer, digital image processing, and expert systems for the engine protection. The feasibility of IR leak plume detection is evaluated on subscale simulated laboratory plumes to determine sensitivity, signal to noise, and general suitability for the application.

  9. Engineering study of tank leaks related to hydraulic retrieval of sludge from tank 241-C-106. Revision 1

    SciTech Connect

    Lowe, S.S.; Carlos, W.C.; Irwin, J.J.; Khaleel, R.; Kline, N.W.; Ludowise, J.D.; Marusich, R.M.; Rittman, P.D.

    1993-06-09

    This study evaluates hydraulic retrieval (sluicing) of the waste in single-shell tank 241-C-106 with respect to the likelihood of tank leaks, gross volumes of potential leaks, and their consequences. A description of hydraulic retrieval is developed to establish a baseline for the study. Leak models are developed based on postulated leak mechanisms to estimate the amount of waste that could potentially leak while sluicing. Transport models describe the movement of the waste constituents in the surrounding soil and groundwater after a leak occurs. Environmental impact and risk associated with tank leaks are evaluated. Transport of leaked material to the groundwater is found to be dependent on the rate of recharge of moisture in the soil for moderate-sized leaks. Providing a cover over the tank and surrounding area would eliminate the recharge. The bulk of any leaked material would remain in the vicinity of the tank for remedial action.

  10. Management of CSF Leaks Following Vestibular Schwannoma Surgery

    PubMed Central

    Mangus, Brannon D.; Rivas, Alejandro; Yoo, Mi Jin; Alvarez, JoAnn; Wanna, George B.; Haynes, David S.; Bennett, Marc L.

    2011-01-01

    Objective To evaluate the incidence and treatment of CSF leaks after resection of vestibular schwannomas and to propose a treatment algorithm for their management. Study Design Retrospective chart review. Setting Tertiary referral center. Patients Review of 1,922 subjects who underwent resection of vestibular schwannomas from 1970 through 2010. Intervention Surgical resection of vestibular schwannoma. Main Outcome Measures Patient demographics, surgical approach used, CSF leak incidence, meningitis, treatment and success in the management of CSF leaks. Results Postoperative CSF leaks were observed in 12.9% of our patients. There was no significant difference between the type of approach and the presence of CSF leak with translabyrinthine, suboccipital and middle fossa CSF leak rates of 12%, 12%, and 13% respectively (p=0.07). Patients presented with a wound leak or rhinorrhea almost equally. Ultimately, 92% of patients with rhinorrhea underwent surgical intervention. The probability of a patient with rhinorrhea requiring a second intervention was higher when the initial intervention was conservative rather than surgical. However, the probability of a patient with a wound leak requiring a second intervention was essentially the same when initially treated conservatively or surgically. Conclusion Our data suggests that there is no difference in CSF leak rates between the different surgical approaches. The appropriate treatment strategy is dependent on the presentation of the CSF. While conservative treatment is effective for managing wound leaks, it is less effective in managing patients with rhinorrhea. Therefore, surgical treatments should play an early role in the treatment algorithm of patients with CSF rhinorrhea. PMID:21970847

  11. Chemochromic Hydrogen Leak Detectors

    NASA Technical Reports Server (NTRS)

    Roberson, Luke; Captain, Janine; Williams, Martha; Smith, Trent; Tate, LaNetra; Raissi, Ali; Mohajeri, Nahid; Muradov, Nazim; Bokerman, Gary

    2009-01-01

    At NASA, hydrogen safety is a key concern for space shuttle processing. Leaks of any level must be quickly recognized and addressed due to hydrogen s lower explosion limit. Chemo - chromic devices have been developed to detect hydrogen gas in several embodiments. Because hydrogen is odorless and colorless and poses an explosion hazard, there is an emerging need for sensors to quickly and accurately detect low levels of leaking hydrogen in fuel cells and other advanced energy- generating systems in which hydrogen is used as fuel. The device incorporates a chemo - chromic pigment into a base polymer. The article can reversibly or irreversibly change color upon exposure to hydrogen. The irreversible pigment changes color from a light beige to a dark gray. The sensitivity of the pigment can be tailored to its application by altering its exposure to gas through the incorporation of one or more additives or polymer matrix. Furthermore, through the incorporation of insulating additives, the chemochromic sensor can operate at cryogenic temperatures as low as 78 K. A chemochromic detector of this type can be manufactured into any feasible polymer part including injection molded plastic parts, fiber-spun textiles, or extruded tapes. The detectors are simple, inexpensive, portable, and do not require an external power source. The chemochromic detectors were installed and removed easily at the KSC launch pad without need for special expertise. These detectors may require an external monitor such as the human eye, camera, or electronic detector; however, they could be left in place, unmonitored, and examined later for color change to determine whether there had been exposure to hydrogen. In one type of envisioned application, chemochromic detectors would be fabricated as outer layers (e.g., casings or coatings) on high-pressure hydrogen storage tanks and other components of hydrogen-handling systems to provide visible indications of hydrogen leaks caused by fatigue failures or

  12. Modeling the Progression of Epithelial Leak Caused by Overdistension

    PubMed Central

    Hamlington, Katharine L.; Ma, Baoshun; Smith, Bradford J.; Bates, Jason H. T.

    2016-01-01

    Mechanical ventilation is necessary for treatment of the acute respiratory distress syndrome but leads to overdistension of the open regions of the lung and produces further damage. Although we know that the excessive stresses and strains disrupt the alveolar epithelium, we know little about the relationship between epithelial strain and epithelial leak. We have developed a computational model of an epithelial monolayer to simulate leak progression due to overdistension and to explain previous experimental findings in mice with ventilator-induced lung injury. We found a nonlinear threshold-type relationship between leak area and increasing stretch force. After the force required to initiate the leak was reached, the leak area increased at a constant rate with further increases in force. Furthermore, this rate was slower than the rate of increase in force, especially at end-expiration. Parameter manipulation changed only the leak-initiating force; leak area growth followed the same trend once this force was surpassed. These results suggest that there is a particular force (analogous to ventilation tidal volume) that must not be exceeded to avoid damage and that changing cell physical properties adjusts this threshold. This is relevant for the development of new ventilator strategies that avoid inducing further injury to the lung. PMID:26951764

  13. CSNI specialist meeting on leak-before-break in nuclear reactor piping: proceedings

    SciTech Connect

    Not Available

    1984-08-01

    On September 1 and 2, 1983, the CSNI subcommittee on primary system integrity held a special meeting in Monterey, California, on the subject of leak-before-break in nuclear reactor piping systems. The purpose of the meeting was to provide an international forum for the exchange of ideas, positions, and research results; to identify areas requiring additional research and development; and to determine the general attitude toward acceptance of the leak-before-break concept. The importance of the leak-before-break issue was evidenced by excellent attendance at the meeting and through active participation by the meeting attendees. Approximately 125 people representing fifteen different nations attended the meeting. The meeting was divided into four technical sessions addressing the following areas: Application of Piping Fracture Mechanics to Leak-Before Break, Leak Rate and Leak Detection, Leak-Before-Break Studies, Methods and Results, Current and Proposed Positions on Leak-Before-Break.

  14. Rapid, Vehicle-Based Identification of Location and Magnitude of Urban Natural Gas Pipeline Leaks.

    PubMed

    von Fischer, Joseph C; Cooley, Daniel; Chamberlain, Sam; Gaylord, Adam; Griebenow, Claire J; Hamburg, Steven P; Salo, Jessica; Schumacher, Russ; Theobald, David; Ham, Jay

    2017-04-04

    Information about the location and magnitudes of natural gas (NG) leaks from urban distribution pipelines is important for minimizing greenhouse gas emissions and optimizing investment in pipeline management. To enable rapid collection of such data, we developed a relatively simple method using high-precision methane analyzers in Google Street View cars. Our data indicate that this automated leak survey system can document patterns in leak location and magnitude within and among cities, even without wind data. We found that urban areas with prevalent corrosion-prone distribution lines (Boston, MA, Staten Island, NY, and Syracuse, NY), leaked approximately 25-fold more methane than cities with more modern pipeline materials (Burlington, VT, and Indianapolis, IN). Although this mobile monitoring method produces conservative estimates of leak rates and leak counts, it can still help prioritize both leak repairs and replacement of leak-prone sections of distribution lines, thus minimizing methane emissions over short and long terms.

  15. Ultrasonic Leak Detection System

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C. (Inventor); Moerk, J. Steven (Inventor)

    1998-01-01

    A system for detecting ultrasonic vibrations. such as those generated by a small leak in a pressurized container. vessel. pipe. or the like. comprises an ultrasonic transducer assembly and a processing circuit for converting transducer signals into an audio frequency range signal. The audio frequency range signal can be used to drive a pair of headphones worn by an operator. A diode rectifier based mixing circuit provides a simple, inexpensive way to mix the transducer signal with a square wave signal generated by an oscillator, and thereby generate the audio frequency signal. The sensitivity of the system is greatly increased through proper selection and matching of the system components. and the use of noise rejection filters and elements. In addition, a parabolic collecting horn is preferably employed which is mounted on the transducer assembly housing. The collecting horn increases sensitivity of the system by amplifying the received signals. and provides directionality which facilitates easier location of an ultrasonic vibration source.

  16. Complications of rectal anastomoses with end-to-end anastomosis (EEA) stapling instrument. Clinical and radiological leak rates and some practical hints.

    PubMed Central

    Dorricott, N. J.; Baddeley, R. M.; Keighley, M. R.; Lee, J.; Oates, G. D.; Alexander-Williams, J.

    1982-01-01

    The complications and results of rectal anastomoses carried out with the end-to-end anastomosis (EEA) stapling instrument on 50 patients by 5 consultant surgeons are recorded. There was a clinical leakage rate of 6% and a radiological leakage rate of 20% assessed by water-soluble contrast enema. The technique has advantages compared with hand-suture by allowing low anastomoses and preservation of sphincters and is accompanied by an acceptably low leakage rate. Despite the cost of disposable cartridges these advantages make the technique economical because of the avoidance of colostomies and reduction in hospital stay. Images FIG. 1 FIG. 2 PMID:7044253

  17. Absolute Determination for the Sodium-22(p,gamma)Magnesium-23 Reaction Rate: Consequences for Nucleosynthesis of Sodium-22 in Novae

    NASA Astrophysics Data System (ADS)

    Sallaska, Anne L.

    2010-11-01

    Hydrodynamic simulations of classical novae on ONe white dwarfs predict substantial production of 22Na. Observation of 22Na decay should be correlated with the corresponding nova because the half life of 22Na is only 2.6 years. The 1275-keV gamma ray from the beta decay of 22Na is, therefore, an excellent diagnostic for the nova phenomenon and a long-sought target of gamma-ray telescopes. Nova simulations determine the maximum 22Na-detection distance to be < 1 kpc for the INTEGRAL spectrometer SPI, consistent with its non-observation to date. However, model estimates are strongly dependent on the thermonuclear rate of the 22Na(p, gamma)23Mg reaction, which is the main destruction mechanism of 22Na in novae. The 22Na(p,gamma)23Mg rate is expected to be dominated by narrow, isolated resonances with Ep < 300 key. The currently employed rate is based on a single set of absolute resonance-strength measurements with Ep ≥ 290 keV, and one relative measurement of resonances with Ep ≥ 214 keV. Recently, a new level has been found in 23Mg which would correspond to a resonance at Ep = 198 keV that might dominate the reaction rate at nova temperatures. We have measured the 22Na(p, gamma) 23Mg resonance strengths directly and absolutely, in addition to resonance energies and branches. Proton beams were produced at the University of Washington and delivered to a specially designed beam line that included rastering and cold vacuum protection of the 22Na-implanted targets (fabricated at TRIUMF-ISAC). Two high-purity germanium detectors were employed and surrounded by anticoincidence shields to reduce cosmic backgrounds. Measurements were made on known 22Na+p resonances, which we observed at laboratory energies Ep = 213, 288, 454, 610 keV and on proposed resonances at Ep = 198, 209, and 232 key. The proposed resonances were not observed, and the upper limit placed on the 198-keV resonance strength indicates that the resonance at Ep = 213 keV still dominates the reaction rate

  18. ISS Ammonia Leak Detection Through X-Ray Fluorescence

    NASA Technical Reports Server (NTRS)

    Camp, Jordan; Barthelmy, Scott; Skinner, Gerry

    2013-01-01

    Ammonia leaks are a significant concern for the International Space Station (ISS). The ISS has external transport lines that direct liquid ammonia to radiator panels where the ammonia is cooled and then brought back to thermal control units. These transport lines and radiator panels are subject to stress from micrometeorites and temperature variations, and have developed small leaks. The ISS can accommodate these leaks at their present rate, but if the rate increased by a factor of ten, it could potentially deplete the ammonia supply and impact the proper functioning of the ISS thermal control system, causing a serious safety risk. A proposed ISS astrophysics instrument, the Lobster X-Ray Monitor, can be used to detect and localize ISS ammonia leaks. Based on the optical design of the eye of its namesake crustacean, the Lobster detector gives simultaneously large field of view and good position resolution. The leak detection principle is that the nitrogen in the leaking ammonia will be ionized by X-rays from the Sun, and then emit its own characteristic Xray signal. The Lobster instrument, nominally facing zenith for its astrophysics observations, can be periodically pointed towards the ISS radiator panels and some sections of the transport lines to detect and localize the characteristic X-rays from the ammonia leaks. Another possibility is to use the ISS robot arm to grab the Lobster instrument and scan it across the transport lines and radiator panels. In this case the leak detection can be made more sensitive by including a focused 100-microampere electron beam to stimulate X-ray emission from the leaking nitrogen. Laboratory studies have shown that either approach can be used to locate ammonia leaks at the level of 0.1 kg/day, a threshold rate of concern for the ISS. The Lobster instrument uses two main components: (1) a microchannel plate optic (also known as a Lobster optic) that focuses the X-rays and directs them to the focal plane, and (2) a CCD (charge

  19. Cerebrospinal fluid leaks following septoplasty.

    PubMed

    Venkatesan, Naren N; Mattox, Douglas E; Del Gaudio, John M

    2014-12-01

    We conducted a retrospective review to identify the characteristics of cerebrospinal fluid (CSF) leak in patients who had undergone septoplasty and in selected patients who had experienced a spontaneous CSF leak. CSF leak is a known but infrequently reported complication of septoplasty; to the best of our knowledge, only 4 cases have been previously published in the literature. A review of our institution's database revealed 3 cases of postseptoplasty CSF leak. We reviewed all the available data to look for any commonalities among these 7 cases. In addition, we reviewed 6 cases of spontaneous CSF leak selected from our database for the same purpose. For all patients, we noted the side of the cribriform plate defect, its size and, for the postseptoplasty cases, the interval between the septoplasty and the leak repair. Overall, we found that leaks were much more common on the right side than on the left. The sizes of the leaks in the 2 postseptoplasty groups were comparable (mean: 14.0 × 6.4 mm). The interval between septoplasty and leak repair ranged from 2.5 to 20 years in our cases and from 3 days to 22 weeks in the previously published cases. All 3 of the postseptoplasty patients in our database presented with clear rhinorrhea. Two of the 3 patients had meningitis; 1 of these 2 also had pneumocephalus. Of the 6 cases of spontaneous CSF leaks, 4 occurred on the right and 2 on the left; the average size of the defect was 5.8 mm in the greatest dimension. The finding that cribriform plate defects after septoplasty were typically right-sided likely reflects the prevalence of left-sided surgical approaches. Also, the fact that the defects were larger in the postseptoplasty cases than in the spontaneous cases is likely attributable to the torque effect toward the thin skull base that occurs when the perpendicular plate is twisted during septoplasty.

  20. Expandable coating cocoon leak detection system

    NASA Technical Reports Server (NTRS)

    Hauser, R. L.; Kochansky, M. C.

    1972-01-01

    Development of system and materials for detecting leaks in cocoon protective coatings are discussed. Method of applying materials for leak determination is presented. Pressurization of system following application of materials will cause formation of bubble if leak exists.

  1. Instrumentation system to implement leak test program

    SciTech Connect

    Turner, W.J.; Brown, R.; Rael, D.

    1997-05-01

    HVAC equipment, gloveboxes, and other types of enclosures are required to meet rigid well-defined leak rates when they are to be installed in a nuclear facility. This paper describes two implementations of an instrumentation system that is used to test leak rates on heating, ventilation, and air conditioning (HVAC) plenums, gloveboxes, and experimental chambers, etc. One of the implementations used a programmable logic controller (PLC). The other used what is probably a simpler system based on FlexNet{reg_sign} modules. The emphasis on both systems was on automatic data collection, automatic report generation, and validation of the test results to ERDA 76-21 and ASME-N510. The data are collected using input modules connected to the PLC in one case. In the other case the data are collected using the FlexNet{reg_sign} modules. In both cases, the data are stored and the reports are generated in a spreadsheet.

  2. A Leak Monitor for Industry

    NASA Technical Reports Server (NTRS)

    1996-01-01

    GenCorp Aerojet Industrial Products, Lewis Research Center, Marshall Space Flight Center, and Case Western Reserve University developed a gas leak detection system, originally for use with the Space Shuttle propulsion system and reusable launch vehicles. The Model HG200 Automated Gas Leak Detection System has miniaturized sensors that can identify extremely low concentrations of hydrogen without requiring oxygen. A microprocessor-based hardware/software system monitors the sensors and displays the source and magnitude of hydrogen leaks in real time. The system detects trace hydrogen around pipes, connectors, flanges and pressure tanks, and has been used by Ford Motor Company in the production of a natural gas-powered car.

  3. Measurement of Submerged Oil/Gas Leaks using ROV Video

    NASA Astrophysics Data System (ADS)

    Shaffer, Franklin; de Vera, Giorgio; Lee, Kenneth; Savas, Ömer

    2013-11-01

    Drilling for oil or gas in the Gulf of Mexico is increasing rapidly at depths up to three miles. The National Commission on the Deepwater Horizon Oil Leak concluded that inaccurate estimates of the leak rate from the Deepwater Horizon caused an inadequate response and attempts to cap the leak to fail. The first response to a submerged oil/gas leak will be to send a Remotely Operated Vehicle (ROV) down to view the leak. During the response to the Deepwater Horizon crisis, the authors Savas and Shaffer were members of the Flow Rate Technical Group's Plume Team who used ROV video to develop the FRTG's first official estimates of the oil leak rate. Savas and Shaffer developed an approach using the larger, faster jet features (e.g., turbulent eddies, vortices, entrained particles) in the near-field developing zone to measure discharge rates. The authors have since used the Berkeley Tow Tank to test this approach on submerged dye-colored water jets and compressed air jets. Image Correlation Velocimetry has been applied to measure the velocity of visible features. Results from tests in the Berkeley Tow Tank and submerged oil jets in the OHMSETT facility will be presented.

  4. Management of low colorectal anastomotic leak: Preserving the anastomosis.

    PubMed

    Blumetti, Jennifer; Abcarian, Herand

    2015-12-27

    Anastomotic leak continues to be a dreaded complication after colorectal surgery, especially in the low colorectal or coloanal anastomosis. However, there has been no consensus on the management of the low colorectal anastomotic leak. Currently operative procedures are reserved for patients with frank purulent or feculent peritonitis and unstable vital signs, and vary from simple fecal diversion with drainage to resection of the anastomosis and closure of the rectal stump with end colostomy (Hartmann's procedure). However, if the patient is stable, and the leak is identified days or even weeks postoperatively, less aggressive therapeutic measures may result in healing of the leak and salvage of the anastomosis. Advances in diagnosis and treatment of pelvic collections with percutaneous treatments, and newer methods of endoscopic therapies for the acutely leaking anastomosis, such as use of the endosponge, stents or clips, have greatly reduced the need for surgical intervention in selected cases. Diverting ileostomy, if not already in place, may be considered to reduce fecal contamination. For subclinical leaks or those that persist after the initial surgery, endoluminal approaches such as injection of fibrin sealant, use of endoscopic clips, or transanal closure of the very low anastomosis may be utilized. These newer techniques have variable success rates and must be individualized to the patient, with the goal of treatment being restoration of gastrointestinal continuity and healing of the anastomosis. A review of the treatment of low colorectal anastomotic leaks is presented.

  5. Management of low colorectal anastomotic leak: Preserving the anastomosis

    PubMed Central

    Blumetti, Jennifer; Abcarian, Herand

    2015-01-01

    Anastomotic leak continues to be a dreaded complication after colorectal surgery, especially in the low colorectal or coloanal anastomosis. However, there has been no consensus on the management of the low colorectal anastomotic leak. Currently operative procedures are reserved for patients with frank purulent or feculent peritonitis and unstable vital signs, and vary from simple fecal diversion with drainage to resection of the anastomosis and closure of the rectal stump with end colostomy (Hartmann’s procedure). However, if the patient is stable, and the leak is identified days or even weeks postoperatively, less aggressive therapeutic measures may result in healing of the leak and salvage of the anastomosis. Advances in diagnosis and treatment of pelvic collections with percutaneous treatments, and newer methods of endoscopic therapies for the acutely leaking anastomosis, such as use of the endosponge, stents or clips, have greatly reduced the need for surgical intervention in selected cases. Diverting ileostomy, if not already in place, may be considered to reduce fecal contamination. For subclinical leaks or those that persist after the initial surgery, endoluminal approaches such as injection of fibrin sealant, use of endoscopic clips, or transanal closure of the very low anastomosis may be utilized. These newer techniques have variable success rates and must be individualized to the patient, with the goal of treatment being restoration of gastrointestinal continuity and healing of the anastomosis. A review of the treatment of low colorectal anastomotic leaks is presented. PMID:26730283

  6. Predictors of alveolar air leaks.

    PubMed

    Loran, David B; Woodside, Kenneth J; Cerfolio, Robert J; Zwischenberger, Joseph B

    2002-08-01

    Persistent air leaks are caused by the failure of the postoperative lung to achieve a configuration that is physiologically amenable to healing. The raw pulmonary surface caused by the dissection of the fissure often is separated from the pleura, and the air leak fails to close. Additionally, higher air flow thorough an alveolar-pleural fistula seems to keep the fistula open. Other factors that interfere with wound healing, such as steroid use, diabetes, or malnutrition, can result in persistence of the leak. A thoracic surgeon can minimize the incidence of air leak through meticulous surgical technique and can identify patients in whom the balance of risks (Table 1) and benefits warrant operative intervention based on an understanding of the underlying pathophysiology.

  7. Leak detection with expandable coatings

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Developed and evaluated is a system for leak detection that can be easily applied over separable connectors and that expands into a bubble or balloon if a leak is present. This objective is accomplished by using thin films of Parafilm tape wrapped over connectors, which are then overcoated with a special formulation. The low yield strength and the high elongation of the envelope permit bubble formation if leakage occurs. This system is appropriate for welds and other hardware besides separable connectors. The practical limit of this system appears to be for leaks exceeding 0.000001 cc/sec. If this envelope is used to trap gases for mass spectrometer inspection, leaks in the range of ten to the minus 8th power cc/sec. may be detectable.

  8. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  9. Leak test adapter for containers

    DOEpatents

    Hallett, Brian H.; Hartley, Michael S.

    1996-01-01

    An adapter is provided for facilitating the charging of containers and leak testing penetration areas. The adapter comprises an adapter body and stem which are secured to the container's penetration areas. The container is then pressurized with a tracer gas. Manipulating the adapter stem installs a penetration plug allowing the adapter to be removed and the penetration to be leak tested with a mass spectrometer. Additionally, a method is provided for using the adapter.

  10. Hydrogen leak detection in the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Barile, Ronald G

    1992-01-01

    This study focuses on a helium gas jet flowing into room air. Measurements of helium concentration and velocity in the jet-air mixture are reported. The objective is to learn about jet characteristics so that dynamically similar hydrogen leaks may be located in the Space Shuttle. The hazardous gas detection system (HGDS) in the mobile launch pad uses mass spectrometers to monitor the shuttle environment for leaks. The mass spectrometers are fed by long sample tubes which draw gas from the payload bay, mid body, aft engine compartment and external tank. The overall purpose of this study is to improve the HGDS especially in its potential for locating hydrogen leaks. A rapid-response leak detection experiment was designed, built, and tested, following on the work done in this program last summer. The apparatus included a Perkin Elmer MGA-1200 mass spectrometer and air velocity transducer, both monitored by a Macintosh IIFX computer using LabVIEW software. A jet of helium flowing into the lab air simulated a gas leak. Steady helium or hydrogen-nitrogen jets were logged for concentration and velocity, and the power spectral density of each was computed. Last year, large eddies and vortices were visually seen with Schlieren imaging, and they were detected in the time plots of the various instruments. The response time of the MGA-1200 was found in the range of 0.05 to 0.1 sec. Pulsed concentration waves were clearly detected at 25 cycles per sec by spectral analysis of MGA data. No peaks were detected in the power spectrum, so in the present study, 10 Hz bandwidth-averaged power levels were examined at regular frequency intervals. The practical consequences of last year's study are as follows: sampling frequency should be increased above the present rate of 1 sample per second so that transients could be observed and analyzed with frequency response methods. Many more experiments and conditions were observed in this second summer, including the effects of orifice diameter

  11. Validation of absolute axial neutron flux distribution calculations with MCNP with 197Au(n,γ)198Au reaction rate distribution measurements at the JSI TRIGA Mark II reactor.

    PubMed

    Radulović, Vladimir; Štancar, Žiga; Snoj, Luka; Trkov, Andrej

    2014-02-01

    The calculation of axial neutron flux distributions with the MCNP code at the JSI TRIGA Mark II reactor has been validated with experimental measurements of the (197)Au(n,γ)(198)Au reaction rate. The calculated absolute reaction rate values, scaled according to the reactor power and corrected for the flux redistribution effect, are in good agreement with the experimental results. The effect of different cross-section libraries on the calculations has been investigated and shown to be minor.

  12. Space Shuttle Main Engine Propellant Path Leak Detection Using Sequential Image Processing

    NASA Technical Reports Server (NTRS)

    Smith, L. Montgomery; Malone, Jo Anne; Crawford, Roger A.

    1995-01-01

    Initial research in this study using theoretical radiation transport models established that the occurrence of a leak is accompanies by a sudden but sustained change in intensity in a given region of an image. In this phase, temporal processing of video images on a frame-by-frame basis was used to detect leaks within a given field of view. The leak detection algorithm developed in this study consists of a digital highpass filter cascaded with a moving average filter. The absolute value of the resulting discrete sequence is then taken and compared to a threshold value to produce the binary leak/no leak decision at each point in the image. Alternatively, averaging over the full frame of the output image produces a single time-varying mean value estimate that is indicative of the intensity and extent of a leak. Laboratory experiments were conducted in which artificially created leaks on a simulated SSME background were produced and recorded from a visible wavelength video camera. This data was processed frame-by-frame over the time interval of interest using an image processor implementation of the leak detection algorithm. In addition, a 20 second video sequence of an actual SSME failure was analyzed using this technique. The resulting output image sequences and plots of the full frame mean value versus time verify the effectiveness of the system.

  13. Mitigated Transfer Line Leaks that Result in Surface Pools and Spray Leaks into Pits

    SciTech Connect

    HEY, B.E.

    1999-12-07

    This analysis provides radiological and toxicological consequence calculations for postulated mitigated leaks during transfers of six waste compositions. Leaks in Cleanout Boxes equipped with supplemental covers and leaks in pits are analyzed.

  14. Leak testing of IR sensor dewars to 1E-15 std He/s

    NASA Astrophysics Data System (ADS)

    Sasaki, Y. Tito; Bergquist, Lyle E.

    1990-09-01

    The results of tests for leakage performed on ten IR sensor dewars are presented, and the design principles of the new testing devices are discussed. The ultrasensitive leak detector used for testing is compared to conventional detectors. The superfine leak calibrator consisting of a tracer gas supply, an aliquot volume, a pressure transducer, temperature gage, and valves was used to measure leak rates in the E-4 to E-12 std cc He/s range. The testing method is explained, including the gases used, the quadrupole mass analyzer, the reference leak calibration, and the temperature coefficient of the reference leak. The test results of the IR sensor dewars are shown: seven showed leak rates in the E-15 std cc He/s range, two had no detectable leaks, and one had a mid-range E-14 leak. The shelf lives of the dewars are calculated based on the results. The vacuum integrity of small IR sensor dewars can be reliably tested to the range of 1E-15 std cc He/s using the ultrasensitive leak detector and the superfine leak calibrator.

  15. Passive vapor monitoring of underground storage tanks for leak detection.

    PubMed

    Weber, D; Schwille, F

    1991-02-01

    Passive vapor monitoring of underground storage tanks (USTs) containing volatile hydrocarbons at locations external to the tank (an external system) is touted as a fast and effective method of leak detection. However, major gaps remain in our knowledge of the physical processes that relate a measured vapor concentration to the leak rate, thus making network design according to a quantitative design criterion nearly impossible, and differentiation between surface spills and a leaking UST requires certain levels of sophistication in the leak detection system and in the analysis that are not usually available. Heavier-than-air vapors from the constituents of stored hydrocarbons could result in a density-driven convective propagation component that complicates the design of leak detection systems, and finally, detection times are highly sensitive to concentration detection threshold levels set by the system. The use of inadequate systems and analyses can lead to either wasted efforts or excessive subsurface contamination. This paper discusses the physical processes involved, explores the above aspects of external passive vapor leak detection design, and suggests some alternatives as they pertain to gasoline service stations.

  16. Hazardous Gas Leak Analysis in the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Barile, Ronald G.

    1991-01-01

    Helium tests of the main propulsion system in the Space Shuttle and on hydrogen leaks are examined. The hazardous gas detection system (HGDS) in the mobile launch pad uses mass spectrometers (MS) to monitor the shuttle environment for leaks. The mass spectrometers are fed by long tubes to sample gas from the payload bay, mid-body, aft engine compartment, and external tank. The purpose is to improve the HGDS, especially in its potential for locating cryogen leaks. Pre-existing leak data was analyzed for transient information to determine if the leak location could be pinpointed from test data. A rapid response leak detection experiment was designed, built, and tested. Large eddies and vortices were visually seen with Schlieren imaging, and they were detected in the time plots of the various instruments. The response time of the MS was found in the range of 0.05 to 0.1 sec. Pulsed concentration waves were clearly detected at 25 cycles per sec by spectral analysis of MS data. One conclusion is that the backup HGDS sampling frequency should be increased above the present rate of 1 sample per second.

  17. Mapping urban pipeline leaks: methane leaks across Boston.

    PubMed

    Phillips, Nathan G; Ackley, Robert; Crosson, Eric R; Down, Adrian; Hutyra, Lucy R; Brondfield, Max; Karr, Jonathan D; Zhao, Kaiguang; Jackson, Robert B

    2013-02-01

    Natural gas is the largest source of anthropogenic emissions of methane (CH(4)) in the United States. To assess pipeline emissions across a major city, we mapped CH(4) leaks across all 785 road miles in the city of Boston using a cavity-ring-down mobile CH(4) analyzer. We identified 3356 CH(4) leaks with concentrations exceeding up to 15 times the global background level. Separately, we measured δ(13)CH(4) isotopic signatures from a subset of these leaks. The δ(13)CH(4) signatures (mean = -42.8‰ ± 1.3‰ s.e.; n = 32) strongly indicate a fossil fuel source rather than a biogenic source for most of the leaks; natural gas sampled across the city had average δ(13)CH(4) values of -36.8‰ (± 0.7‰ s.e., n = 10), whereas CH(4) collected from landfill sites, wetlands, and sewer systems had δ(13)CH(4) signatures ~20‰ lighter (μ = -57.8‰, ± 1.6‰ s.e., n = 8). Repairing leaky natural gas distribution systems will reduce greenhouse gas emissions, increase consumer health and safety, and save money.

  18. Absolutely classical spin states

    NASA Astrophysics Data System (ADS)

    Bohnet-Waldraff, F.; Giraud, O.; Braun, D.

    2017-01-01

    We introduce the concept of "absolutely classical" spin states, in analogy to absolutely separable states of bipartite quantum systems. Absolutely classical states are states that remain classical (i.e., a convex sum of projectors on coherent states of a spin j ) under any unitary transformation applied to them. We investigate the maximal size of the ball of absolutely classical states centered on the maximally mixed state and derive a lower bound for its radius as a function of the total spin quantum number. We also obtain a numerical estimate of this maximal radius and compare it to the case of absolutely separable states.

  19. The ISS 2B PVTCS Ammonia Leak: An Operational History

    NASA Technical Reports Server (NTRS)

    Vareha, Anthony

    2014-01-01

    In 2006, the Photovoltaic Thermal Control System (PVTCS) for the International Space Station's 2B power channel began leaking ammonia at a rate of approximately 1.5lbm/year (out of a starting approximately 53lbm system ammonia mass). Initially, the operations strategy was "feed the leak," a strategy successfully put into action via Extra Vehicular Activity during the STS-134 mission. During this mission the system was topped off with ammonia piped over from a separate thermal control system. This recharge was to have allowed for continued power channel operation into 2014 or 2015, at which point another EVA would have been required. Without these periodic EVAs to refill the 2B coolant system, the channel would eventually leak enough fluid as to risk pump cavitation and system failure, resulting in the loss of the 2B power channel - the most critical of the Space Station's 8 power channels. In mid-2012, the leak rate increased to approximately 5lbm/year. Once discovered, an EVA was planned and executed within a 5 week timeframe to drastically alter the architecture of the PVTCS via connection to a dormant thermal control system not intended to be utilized as anything other than spare components. The purpose of this rerouting of the TCS was to increase system volume and to isolate the photovoltaic radiator, thought to be the likely leak source. This EVA was successfully executed on November 1st, 2012 and left the 2B PVTCS in a configuration where the system was now being adequately cooled via a totally different radiator than what the system was designed to utilize. Unfortunately, data monitoring over the next several months showed that the isolated radiator was not leaking, and the system itself continued to leak steadily until May 9th, 2013. It was on this day that the ISS crew noticed the visible presence of ammonia crystals escaping from the 2B channel's truss segment, signifying a rapid acceleration of the leak from 5lbm/year to 5lbm/day. Within 48 hours of the

  20. Ryanodine receptors as leak channels.

    PubMed

    Guerrero-Hernández, Agustín; Ávila, Guillermo; Rueda, Angélica

    2014-09-15

    Ryanodine receptors are Ca(2+) release channels of internal stores. This review focuses on those situations and conditions that transform RyRs from a finely regulated ion channel to an unregulated Ca(2+) leak channel and the pathological consequences of this alteration. In skeletal muscle, mutations in either CaV1.1 channel or RyR1 results in a leaky behavior of the latter. In heart cells, RyR2 functions normally as a Ca(2+) leak channel during diastole within certain limits, the enhancement of this activity leads to arrhythmogenic situations that are tackled with different pharmacological strategies. In smooth muscle, RyRs are involved more in reducing excitability than in stimulating contraction so the leak activity of RyRs in the form of Ca(2+) sparks, locally activates Ca(2+)-dependent potassium channels to reduce excitability. In neurons the enhanced activity of RyRs is associated with the development of different neurodegenerative disorders such as Alzheimer and Huntington diseases. It appears then that the activity of RyRs as leak channels can have both physiological and pathological consequences depending on the cell type and the metabolic condition.

  1. Pipe Leak Detection Technology Development

    EPA Science Inventory

    The U. S. Environmental Protection Agency (EPA) has determined that one of the nation’s biggest infrastructural needs is the replacement or rehabilitation of the water distribution and transmission systems. The institution of more effective pipe leak detection technology will im...

  2. Optical Detection Of Cryogenic Leaks

    NASA Technical Reports Server (NTRS)

    Wyett, Lynn M.

    1988-01-01

    Conceptual system identifies leakage without requiring shutdown for testing. Proposed device detects and indicates leaks of cryogenic liquids automatically. Detector makes it unnecessary to shut equipment down so it can be checked for leakage by soap-bubble or helium-detection methods. Not necessary to mix special gases or other materials with cryogenic liquid flowing through equipment.

  3. LOCATING LEAKS WITH ACOUSTIC TECHNOLOGY

    EPA Science Inventory

    Many water distribution systems in this country are almost 100 years old. About 26 percent of piping in these systems is made of unlined cast iron or steel and is in poor condition. Many methods that locate leaks in these pipes are time-consuming, costly, disruptive to operations...

  4. Stochastic Consequence Analysis for Waste Leaks

    SciTech Connect

    HEY, B.E.

    2000-05-31

    This analysis evaluates the radiological consequences of potential Hanford Tank Farm waste transfer leaks. These include ex-tank leaks into structures, underneath the soil, and exposed to the atmosphere. It also includes potential misroutes, tank overflow

  5. Rapid leak detection with liquid crystals

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Iceland, W. F.; Ruppe, E. P.

    1978-01-01

    Small leaks in vacuum lines are detected by applying liquid-crystal coating, warming suspected area, and observing color change due to differential cooling by leak jet. Technique is used on inside or outside walls of vacuum-jacketed lines.

  6. UNBIASED MOMENT-RATE SPECTRA AND ABSOLUTE SITE EFFECTS IN THE KACHCHH BASIN, INDIA, FROM THE ANALYSIS OF THE AFTERSHOCKS OF THE 2001 Mw 7.6 BHUJ EARTHQUAKE

    SciTech Connect

    Malagnini, L; Bodin, P; Mayeda, K; Akinci, A

    2005-05-04

    What can be learned about absolute site effects on ground motions and about earthquake source spectra from recordings at temporary seismic stations, none of which could be considered a 'reference' (hard rock) site, for which no geotechnical information is available, in a very poorly instrumented region? This challenge motivated our current study of aftershocks of the 2001 Mw 7.6 Bhuj earthquake, in Western India. Crustal attenuation and spreading relationships based on the same data used here were determined in an earlier study. In this paper we decouple the ambiguity between absolute source radiation and site effects by first computing robust estimates of moment-rate spectra of about 200 aftershocks in each of two depth ranges. Using these new estimates of sourcespectra, and our understanding of regional wave propagation, we extract the absolute site terms of the sites of the temporary deployment. Absolute site terms (one for each component of the ground motion, for each station) are computed in an average sense, via an L{sub 1}-norm minimization, and results for each site are averaged over wide ranges of azimuths and takeoff angles. The Bhuj deployment is characterized by a variable shallow geology, mostly of soft sedimentary units. Vertical site terms in the region were observed to be almost featureless and slightly < 1.0 within wide frequency ranges. As a result, H/V spectral ratios mimic the absolute behaviors of absolute horizontal site terms, and they generally overpredict them. On the contrary, with respect to the results for sedimentary rock sites (limestone, dolomite) obtained by Malagnini et al. (2004), H/V spectral ratios in their study did not have much in common with absolute horizontal site terms. Spectral ratios between the vector sum of the computed horizontal site terms for the temporary deployment with respect to the same quantity computed at the hardest rock station available, BAC1, are seriously biased by its non-flat, non-unitary site response

  7. Standard Leak Calibration Facility software system

    SciTech Connect

    McClain, S.K.

    1989-06-01

    A Standard Leak Calibration Facility Software System has been developed and implemented for controlling, and running a standard Leak Calibration Facility. Primary capabilities provided by the software system include computer control of the vacuum system, automatic leak calibration, and data acquisition, manipulation, and storage.

  8. Helium Mass Spectrometer Leak Detection: A Method to Quantify Total Measurement Uncertainty

    NASA Technical Reports Server (NTRS)

    Mather, Janice L.; Taylor, Shawn C.

    2015-01-01

    In applications where leak rates of components or systems are evaluated against a leak rate requirement, the uncertainty of the measured leak rate must be included in the reported result. However, in the helium mass spectrometer leak detection method, the sensitivity, or resolution, of the instrument is often the only component of the total measurement uncertainty noted when reporting results. To address this shortfall, a measurement uncertainty analysis method was developed that includes the leak detector unit's resolution, repeatability, hysteresis, and drift, along with the uncertainty associated with the calibration standard. In a step-wise process, the method identifies the bias and precision components of the calibration standard, the measurement correction factor (K-factor), and the leak detector unit. Together these individual contributions to error are combined and the total measurement uncertainty is determined using the root-sum-square method. It was found that the precision component contributes more to the total uncertainty than the bias component, but the bias component is not insignificant. For helium mass spectrometer leak rate tests where unit sensitivity alone is not enough, a thorough evaluation of the measurement uncertainty such as the one presented herein should be performed and reported along with the leak rate value.

  9. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  10. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  11. Hydrogen Leak Detection Sensor Database

    NASA Technical Reports Server (NTRS)

    Baker, Barton D.

    2010-01-01

    This slide presentation reviews the characteristics of the Hydrogen Sensor database. The database is the result of NASA's continuing interest in and improvement of its ability to detect and assess gas leaks in space applications. The database specifics and a snapshot of an entry in the database are reviewed. Attempts were made to determine the applicability of each of the 65 sensors for ground and/or vehicle use.

  12. 40 CFR 63.1086 - How must I monitor for leaks to cooling water?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... system so that the cooling water flow rate is 51,031 liters per minute or less so that a leak of 3.06 kg... 40 Protection of Environment 11 2014-07-01 2014-07-01 false How must I monitor for leaks to... (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR...

  13. 40 CFR 63.1086 - How must I monitor for leaks to cooling water?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... system so that the cooling water flow rate is 51,031 liters per minute or less so that a leak of 3.06 kg... 40 Protection of Environment 11 2012-07-01 2012-07-01 false How must I monitor for leaks to... (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR...

  14. Schlieren optics for leak detection

    NASA Technical Reports Server (NTRS)

    Peale, Robert E.; Ruffin, Alranzo B.

    1995-01-01

    The purpose of this research was to develop an optical method of leak detection. Various modifications of schlieren optics were explored with initial emphasis on leak detection of the plumbing within the orbital maneuvering system of the space shuttle (OMS pod). The schlieren scheme envisioned for OMS pod leak detection was that of a high contrast pattern on flexible reflecting material imaged onto a negative of the same pattern. We find that the OMS pod geometry constrains the characteristic length scale of the pattern to the order of 0.001 inch. Our experiments suggest that optical modulation transfer efficiency will be very low for such patterns, which will limit the sensitivity of the technique. Optical elements which allow a negative of the scene to be reversibly recorded using light from the scene itself were explored for their potential in adaptive single-ended schlieren systems. Elements studied include photochromic glass, bacteriorhodopsin, and a transmissive liquid crystal display. The dynamics of writing and reading patterns were studied using intensity profiles from recorded images. Schlieren detection of index gradients in air was demonstrated.

  15. Comprehensive quantitative analysis on privacy leak behavior.

    PubMed

    Fan, Lejun; Wang, Yuanzhuo; Jin, Xiaolong; Li, Jingyuan; Cheng, Xueqi; Jin, Shuyuan

    2013-01-01

    Privacy information is prone to be leaked by illegal software providers with various motivations. Privacy leak behavior has thus become an important research issue of cyber security. However, existing approaches can only qualitatively analyze privacy leak behavior of software applications. No quantitative approach, to the best of our knowledge, has been developed in the open literature. To fill this gap, in this paper we propose for the first time four quantitative metrics, namely, possibility, severity, crypticity, and manipulability, for privacy leak behavior analysis based on Privacy Petri Net (PPN). In order to compare the privacy leak behavior among different software, we further propose a comprehensive metric, namely, overall leak degree, based on these four metrics. Finally, we validate the effectiveness of the proposed approach using real-world software applications. The experimental results demonstrate that our approach can quantitatively analyze the privacy leak behaviors of various software types and reveal their characteristics from different aspects.

  16. Comprehensive Quantitative Analysis on Privacy Leak Behavior

    PubMed Central

    Fan, Lejun; Wang, Yuanzhuo; Jin, Xiaolong; Li, Jingyuan; Cheng, Xueqi; Jin, Shuyuan

    2013-01-01

    Privacy information is prone to be leaked by illegal software providers with various motivations. Privacy leak behavior has thus become an important research issue of cyber security. However, existing approaches can only qualitatively analyze privacy leak behavior of software applications. No quantitative approach, to the best of our knowledge, has been developed in the open literature. To fill this gap, in this paper we propose for the first time four quantitative metrics, namely, possibility, severity, crypticity, and manipulability, for privacy leak behavior analysis based on Privacy Petri Net (PPN). In order to compare the privacy leak behavior among different software, we further propose a comprehensive metric, namely, overall leak degree, based on these four metrics. Finally, we validate the effectiveness of the proposed approach using real-world software applications. The experimental results demonstrate that our approach can quantitatively analyze the privacy leak behaviors of various software types and reveal their characteristics from different aspects. PMID:24066046

  17. Prediction of Gas Leak Tightness of Superplastically Formed Products

    SciTech Connect

    Snippe, Corijn H. C.; Meinders, T.

    2010-06-15

    In some applications, in this case an aluminium box in a subatomic particle detector containing highly sensitive detecting devices, it is important that a formed sheet should show no gas leak from one side to the other. In order to prevent a trial-and-error procedure to make this leak tight box, a method is set up to predict if a formed sheet conforms to the maximum leak constraint. The technique of superplastic forming (SPF) is used in order to attain very high plastic strains before failure. Since only a few of these boxes are needed, this makes, this generally slow, process an attractive production method. To predict the gas leak of a superplastically formed aluminium sheet in an accurate way, finite element simulations are used in combination with a user-defined material model. This constitutive model couples the leak rate with the void volume fraction. This void volume fraction is then dependent on both the equivalent plastic strain and the applied hydrostatic pressure during the bulge process (backpressure).

  18. Leak detection by acoustic emission monitoring. Phase 1: Feasibility study

    NASA Astrophysics Data System (ADS)

    Lichtenstein, Bernard; Winder, A. A.

    1994-05-01

    This investigation was conducted to determine the feasibility of detecting leaks from underground storage tanks or pipelines using acoustic emissions. An extensive technical literature review established that distinguishable acoustic emission signals will be generated when a storage tank is subjected to deformation stresses. A parametric analysis was performed which indicated that leak rates less than 0.1 gallons per hour can be detected for leak sizes less than 1/32 inch with 99% probability if the transient signals were sensed with an array of accelerometers (cemented to the tank or via acoustic waveguides), each having a sensitivity greater than 250 mv/g over a frequency range of 0.1 to 4000 Hz, and processed in a multi-channel Fourier spectrum analyzer with automatic threshold detection. An acoustic transient or energy release processor could conceivably detect the onset of the leak at the moment of fracture of the tank wall. The primary limitations to realizing reliable and robust acoustic emission monitoring of underground fluid leaks are the various masking noise sources prevalent at Air Force bases, which are attributed to aircraft, motor traffic, pump station operation, and ground tremors.

  19. Using Decision Trees to Detect and Isolate Simulated Leaks in the J-2X Rocket Engine

    NASA Technical Reports Server (NTRS)

    Schwabacher, Mark A.; Aguilar, Robert; Figueroa, Fernando F.

    2009-01-01

    The goal of this work was to use data-driven methods to automatically detect and isolate faults in the J-2X rocket engine. It was decided to use decision trees, since they tend to be easier to interpret than other data-driven methods. The decision tree algorithm automatically "learns" a decision tree by performing a search through the space of possible decision trees to find one that fits the training data. The particular decision tree algorithm used is known as C4.5. Simulated J-2X data from a high-fidelity simulator developed at Pratt & Whitney Rocketdyne and known as the Detailed Real-Time Model (DRTM) was used to "train" and test the decision tree. Fifty-six DRTM simulations were performed for this purpose, with different leak sizes, different leak locations, and different times of leak onset. To make the simulations as realistic as possible, they included simulated sensor noise, and included a gradual degradation in both fuel and oxidizer turbine efficiency. A decision tree was trained using 11 of these simulations, and tested using the remaining 45 simulations. In the training phase, the C4.5 algorithm was provided with labeled examples of data from nominal operation and data including leaks in each leak location. From the data, it "learned" a decision tree that can classify unseen data as having no leak or having a leak in one of the five leak locations. In the test phase, the decision tree produced very low false alarm rates and low missed detection rates on the unseen data. It had very good fault isolation rates for three of the five simulated leak locations, but it tended to confuse the remaining two locations, perhaps because a large leak at one of these two locations can look very similar to a small leak at the other location.

  20. Evaluation of advanced and current leak detection system

    SciTech Connect

    Kupperman, D.S.

    1987-01-01

    US Nuclear Regulatory Commission Guide 1.45 recommends the use of at least three different detection methods in reactors to detect leakage. Monitoring of both sump-flow and airborne particulate radioactivity is mandatory. A third method can involve either monitoring of condensate flow rate from air coolers or monitoring of airborne gaseous radioactivity. Although the methods currently used for leak detection reflect the state of the art, other techniques may be developed and used. Since the recommendations of Regulatory Guide 1.45 are not mandatory, Licensee Event Report Compilations have been reviewed to help establish actual capabilities for leak detection. The review of reports which had previously covered the period June 1985 to August 1986, has been extended. The total number of events of significance is now 83. These reports have provided documented, sometimes detailed summaries of reactor leaks.

  1. Assessment of volume and leak measurements during CPAP using a neonatal lung model.

    PubMed

    Fischer, H S; Roehr, C C; Proquitté, H; Wauer, R R; Schmalisch, G

    2008-01-01

    Although several commercial devices are available which allow tidal volume and air leak monitoring during continuous positive airway pressure (CPAP) in neonates, little is known about their measurement accuracy and about the influence of air leaks on volume measurement. The aim of this in vitro study was the validation of volume and leak measurement under CPAP using a commercial ventilatory device, taking into consideration the clinical conditions in neonatology. The measurement accuracy of the Leoni ventilator (Heinen & Löwenstein, Germany) was investigated both in a leak-free system and with leaks simulated using calibration syringes (2-10 ml, 20-100 ml) and a mechanical lung model. Open tubes of variable lengths were connected for leak simulation. Leak flow was measured with the flow-through technique. In a leak-free system the mean relative volume error +/-SD was 3.5 +/- 2.6% (2-10 ml) and 5.9 +/- 0.7% (20-60 ml), respectively. The influence of CPAP level, driving flow, respiratory rate and humidification of the breathing gas on the volume error was negligible. However, an increasing F(i)O(2) caused the measured tidal volume to increase by up to 25% (F(i)O(2) = 1.0). The relative error +/- SD of the leak measurements was -0.2 +/- 11.9%. For leaks > 19%, measured tidal volume was underestimated by more than 10%. In conclusion, the present in vitro study showed that the Leoni allowed accurate volume monitoring under CPAP conditions similar to neonates. Air leaks of up to 90% of patient flow were reliably detected. For an F(i)O(2) > 0.4 and for leaks > 19%, a numerical correction of the displayed volume should be performed.

  2. Low-Leak, High-Flow Poppet Valve

    NASA Technical Reports Server (NTRS)

    Tervo, John N.

    1995-01-01

    Valve with conical poppet modified to incorporate smooth transition to segment of sphere at upstream end of cone. Constitutes sealing surface of poppet; results in leak rate equivalent to ball-type poppet, and extremely low flow losses. Also enables use of loose fit for guiding poppet, with resulting lower manufacturing cost, high reliability, and long operating life.

  3. Temperature dependence for the absolute rate constant for the reaction CH/sub 2/OH + O/sub 2/. -->. HO/sub 2/ + H/sub 2/CO from 215 to 300 K

    SciTech Connect

    Nesbitt, F.L.; Payne, W.A.; Stief, L.J.

    1988-07-14

    The absolute rate constant for the reaction CH/sub 2/OH + O/sub 2/ ..-->.. HO/sub 2/ + H/sub 2/CO has been determined from 215 to 300 K in a discharge flow system at 1-Torr pressure. The decay of CH/sub 2/OH was monitored in excess O/sub 2/ by collision-free sampling mass spectrometry. The temperature dependence observed is quite different from the usual Arrhenius form. For the 215-250 K interval, an activation energy of 3.4 kcal/mol is obtained. Above 250 K, the rate constant increases at a slower rate; previous high-temperature studies (1000-2000 K) again show a faster increase in the rate constant. A possible explanation for these observations is that the reaction mechanism changes from addition at low temperature to direct abstraction at high temperatures.

  4. First experimental determination of the absolute gas-phase rate coefficient for the reaction of OH with 4-hydroxy-2-butanone (4H2B) at 294 K by vapor pressure measurements of 4H2B.

    PubMed

    El Dib, Gisèle; Sleiman, Chantal; Canosa, André; Travers, Daniel; Courbe, Jonathan; Sawaya, Terufat; Mokbel, Ilham; Chakir, Abdelkhaleq

    2013-01-10

    The reaction of the OH radicals with 4-hydroxy-2-butanone was investigated in the gas phase using an absolute rate method at room temperature and over the pressure range 10-330 Torr in He and air as diluent gases. The rate coefficients were measured using pulsed laser photolysis (PLP) of H(2)O(2) to produce OH and laser induced fluorescence (LIF) to measure the OH temporal profile. An average value of (4.8 ± 1.2) × 10(-12) cm(3) molecule(-1) s(-1) was obtained. The OH quantum yield following the 266 nm pulsed laser photolysis of 4-hydroxy-2-butanone was measured for the first time and found to be about 0.3%. The investigated kinetic study required accurate measurements of the vapor pressure of 4-hydroxy-2-butanone, which was measured using a static apparatus. The vapor pressure was found to range from 0.056 to 7.11 Torr between 254 and 323 K. This work provides the first absolute rate coefficients for the reaction of 4-hydroxy-2-butanone with OH and the first experimental saturated vapor pressures of the studied compound below 311 K. The obtained results are compared to those of the literature and the effects of the experimental conditions on the reactivity are examined. The calculated tropospheric lifetime obtained in this work suggests that once emitted into the atmosphere, 4H2B may contribute to the photochemical pollution in a local or regional scale.

  5. [Where is a leak point detected by "the low flow leak test" of anesthetic machines?].

    PubMed

    Omija, K; Tokumine, J; Iha, H; Uehara, M; Nitta, K; Okuda, Y

    1997-10-01

    "The low flow leak test" is recommended for pre-anesthetic inspection of anesthetic machines. We carried out anesthesia compression tests as a standard. Even in that case, often the low flow leak test does not meet the standard. We investigated the point where there is a leak in the anesthetic machine. Observing the leak that fluctuates each time there is detachment or attachment of the canister, the primary cause of the leak is thought to be related to the canister. It is important to carry out an inspection of the canister if the low flow leak test does not meet the standard.

  6. Vacuum leak detector and method

    DOEpatents

    Edwards, Jr., David

    1983-01-01

    Apparatus and method for detecting leakage in a vacuum system involves a moisture trap chamber connected to the vacuum system and to a pressure gauge. Moisture in the trap chamber is captured by freezing or by a moisture adsorbent to reduce the residual water vapor pressure therein to a negligible amount. The pressure gauge is then read to determine whether the vacuum system is leaky. By directing a stream of carbon dioxide or helium at potentially leaky parts of the vacuum system, the apparatus can be used with supplemental means to locate leaks.

  7. Leak detection using structure-borne noise

    NASA Technical Reports Server (NTRS)

    Holland, Stephen D. (Inventor); Chimenti, Dale E. (Inventor); Roberts, Ronald A. (Inventor)

    2010-01-01

    A method for detection and location of air leaks in a pressure vessel, such as a spacecraft, includes sensing structure-borne ultrasound waveforms associated with turbulence caused by a leak from a plurality of sensors and cross correlating the waveforms to determine existence and location of the leak. Different configurations of sensors and corresponding methods can be used. An apparatus for performing the methods is also provided.

  8. Pressure Change Measurement Leak Testing Errors

    SciTech Connect

    Pryor, Jeff M; Walker, William C

    2014-01-01

    A pressure change test is a common leak testing method used in construction and Non-Destructive Examination (NDE). The test is known as being a fast, simple, and easy to apply evaluation method. While this method may be fairly quick to conduct and require simple instrumentation, the engineering behind this type of test is more complex than is apparent on the surface. This paper intends to discuss some of the more common errors made during the application of a pressure change test and give the test engineer insight into how to correctly compensate for these factors. The principals discussed here apply to ideal gases such as air or other monoatomic or diatomic gasses; however these same principals can be applied to polyatomic gasses or liquid flow rate with altered formula specific to those types of tests using the same methodology.

  9. 40 CFR 63.1088 - In what situations may I delay leak repair, and what actions must I take for delay of repair?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... process equipment associated with the leaking heat exchanger. You must document the basis for the... the repair as soon as practical. (3) Calculate the potential emissions from the leaking heat exchanger... substances) in the cooling water from the leaking heat exchanger by the flow rate of the cooling water...

  10. 40 CFR 63.1088 - In what situations may I delay leak repair, and what actions must I take for delay of repair?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... process equipment associated with the leaking heat exchanger. You must document the basis for the... the repair as soon as practical. (3) Calculate the potential emissions from the leaking heat exchanger... substances) in the cooling water from the leaking heat exchanger by the flow rate of the cooling water...

  11. High sensitivity leak detection method and apparatus

    DOEpatents

    Myneni, G.R.

    1994-09-06

    An improved leak detection method is provided that utilizes the cyclic adsorption and desorption of accumulated helium on a non-porous metallic surface. The method provides reliable leak detection at superfluid helium temperatures. The zero drift that is associated with residual gas analyzers in common leak detectors is virtually eliminated by utilizing a time integration technique. The sensitivity of the apparatus of this disclosure is capable of detecting leaks as small as 1 [times] 10[sup [minus]18] atm cc sec[sup [minus]1]. 2 figs.

  12. High sensitivity leak detection method and apparatus

    DOEpatents

    Myneni, Ganapatic R.

    1994-01-01

    An improved leak detection method is provided that utilizes the cyclic adsorption and desorption of accumulated helium on a non-porous metallic surface. The method provides reliable leak detection at superfluid helium temperatures. The zero drift that is associated with residual gas analyzers in common leak detectors is virtually eliminated by utilizing a time integration technique. The sensitivity of the apparatus of this disclosure is capable of detecting leaks as small as 1.times.10.sup.-18 atm cc sec.sup.-1.

  13. Safety upgrades plug car leaks

    SciTech Connect

    Not Available

    1993-08-01

    To lessen the chance of a chemical leak occurring during rail transport, some companies are improving tank car sturdiness and safety by adding such features as top-loading valves, on-board monitoring devices, and thicker, more impact-resistant hulls. Results include a dramatic drop in the number of rail incidents and leak tank cars. Chemicals Division of Olin Corporation (Stamford, Connecticut) has assigned its name to a new fleet of chlorine, caustic soda and toluene diisocyanate (TDI) tank cars. Each car carries the company's Care[trademark]Car registered trademark. The upgrade is part of a company-wide quality improvement process started in 1986. The company requires acoustic emissions (AE) testing on all hazardous materials tank cars. If an area has a defect, it expands and makes a slight sound when subjected to stress. In an AE test, cars are subject to simulated bumps and jolts as in rail shipment. Electronic sensors transfer any stress noises onto a computer screen, where an operator can pinpoint the trouble source.

  14. Estimating Absolute Site Effects

    SciTech Connect

    Malagnini, L; Mayeda, K M; Akinci, A; Bragato, P L

    2004-07-15

    The authors use previously determined direct-wave attenuation functions as well as stable, coda-derived source excitation spectra to isolate the absolute S-wave site effect for the horizontal and vertical components of weak ground motion. They used selected stations in the seismic network of the eastern Alps, and find the following: (1) all ''hard rock'' sites exhibited deamplification phenomena due to absorption at frequencies ranging between 0.5 and 12 Hz (the available bandwidth), on both the horizontal and vertical components; (2) ''hard rock'' site transfer functions showed large variability at high-frequency; (3) vertical-motion site transfer functions show strong frequency-dependence, and (4) H/V spectral ratios do not reproduce the characteristics of the true horizontal site transfer functions; (5) traditional, relative site terms obtained by using reference ''rock sites'' can be misleading in inferring the behaviors of true site transfer functions, since most rock sites have non-flat responses due to shallow heterogeneities resulting from varying degrees of weathering. They also use their stable source spectra to estimate total radiated seismic energy and compare against previous results. they find that the earthquakes in this region exhibit non-constant dynamic stress drop scaling which gives further support for a fundamental difference in rupture dynamics between small and large earthquakes. To correct the vertical and horizontal S-wave spectra for attenuation, they used detailed regional attenuation functions derived by Malagnini et al. (2002) who determined frequency-dependent geometrical spreading and Q for the region. These corrections account for the gross path effects (i.e., all distance-dependent effects), although the source and site effects are still present in the distance-corrected spectra. The main goal of this study is to isolate the absolute site effect (as a function of frequency) by removing the source spectrum (moment-rate spectrum) from

  15. NDE of stainless steel and on-line leak monitoring of LWRs

    SciTech Connect

    Kupperman, D.S.; Claytor, T.N.; Mathieson, T.; Prine, D.W.

    1985-10-01

    The GARD/ANL acoustic leak detection system is under evaluation in the laboratory. Results of laboratory tests with simulated acoustic leak signals and acoustic signals from field-induced intergranular stress corrosion cracks (IGSCCs) indicate that cross-correlation techniques can be used to locate the position of a leak. Leaks from a 2-in. ball valve and a flange were studied and compared with leaks from IGSCCs and fatigue cracks. The dependence of acoustic signal on flow rate and frequency for the valve and the flange was comparable to that of fatigue cracks (thermal and mechanical) and different from that of IGSCCs. Two pipe-to-endcap weldments with overlays were examined. Because the amount of cracking in the specimens was limited, the emphasis was on trying understand the nature of crack overcalling. Four 60-mm-thick cast stainless steel plates with microstructures ranging from equiaxed to primarily columnar grains have been examined with ultrasonic waves. 13 refs., 23 figs.

  16. [The current state of leak in anesthetic machines detected by low flow leak tests].

    PubMed

    Uehara, M; Tokumine, J; Iha, H; Nitta, K; Okuda, Y

    1999-05-01

    To assess the current state of leak in anesthetic machines, we selected 66 units of anesthetic machines for inspection and repair from various medical institutions. Based on a newly designed inspection flow chart a low flow leak test for internal circuits of the anesthetic machines was performed. The conventional low flow leak test was also performed for smooth detection of leak for rational evaluation. Only 39% of the anesthetic machines met the standard of the low flow leak tests, and leak was detected in the remaining 61%. The average residual leak mounted to 0.97 l.min-1, with the maximum of 5.3 l.min-1. Canisters, corrugated tubes, and vaporizers were considered the primary causes of leak. After the inspection and repair, leak in 77.5% of the anesthetic machines either disappeared or decreased and the average residual leak dropped to 0.34 l.min-1. However, 47% of the anesthetic machines still failed to meet the standard of the low flow leak tests. To further improve the situation, more detailed inspection and repair are necessary especially for precise detection of the cause of leak in the internal circuit of anesthetic machines which often remains undetected.

  17. Optomechanics for absolute rotation detection

    NASA Astrophysics Data System (ADS)

    Davuluri, Sankar

    2016-07-01

    In this article, we present an application of optomechanical cavity for the absolute rotation detection. The optomechanical cavity is arranged in a Michelson interferometer in such a way that the classical centrifugal force due to rotation changes the length of the optomechanical cavity. The change in the cavity length induces a shift in the frequency of the cavity mode. The phase shift corresponding to the frequency shift in the cavity mode is measured at the interferometer output to estimate the angular velocity of absolute rotation. We derived an analytic expression to estimate the minimum detectable rotation rate in our scheme for a given optomechanical cavity. Temperature dependence of the rotation detection sensitivity is studied.

  18. Argon Spill Trough Bellows - Leak Test

    SciTech Connect

    Jaques, A.; /Fermilab

    1990-04-30

    The four argon spill trough bellows were leak tested with helium during the week of March 12, 1990. Three passed without incident, but the fourth was found to have a leak in the weld at one of the ring/clamps. The hole was approximately 1/32-inch in diameter (a likely result of a welding burn through) and located on an inflexible portion of the bellows, the ring/clamp. Frank Juravic, who conducted the tests, suggested using grey structural epoxy to plug the leak. The epoxy is metallic with some inherent flexibility. The epoxy was applied and the bellows retested in the same manner as before. The repair was a success as the bellows proved to be leaktight. The bellows were then put in their original shipping crates and placed in storage at Lab C. Included in this report is the manufacturer's spec sheets on the bellows, a copy of the Quality Control Report form and a sketch of the test setup with an explanation of the procedure. On the bellows data sheet entitled 'Analysis of Stress in Bellows', the analysis output is obtained through a theoretical bellows program that uses quadratic equations to approximate characteristic curves for such data as axial, lateral and angular movement and spring rates. The program is best suited for bellows with a wall thickness of at least 0.015-inch and an operating pressure significantly above atmospheric. Thus EJS Inc. warned that the output data would not be very accurate in some instances. The data given on the EJS Inc. sketch sheet should be taken as accurate, though, for it was taken from the actual bellows delivered. The 72-inch length includes the 64.64-inch of bellows section, the (3) 1/2-inch ring/clamps and the (2) 1-1/2-inch end bands. The remainder of the discrepancy is accounted for by a 2.75-inch factory elongation of the bellows from the original free length. The 40-inch compression capability includes the 2.75-inch of factory elongation, the program determined 31.9-inch of compression from free length and 5.35-inch of

  19. Intermediate-Scale Laboratory Experiments of Subsurface Flow and Transport Resulting from Tank Leaks

    SciTech Connect

    Oostrom, Martinus; Wietsma, Thomas W.

    2014-09-30

    Washington River Protection Solutions contracted with Pacific Northwest National Laboratory to conduct laboratory experiments and supporting numerical simulations to improve the understanding of water flow and contaminant transport in the subsurface between waste tanks and ancillary facilities at Waste Management Area C. The work scope included two separate sets of experiments: •Small flow cell experiments to investigate the occurrence of potential unstable fingering resulting from leaks and the limitations of the STOMP (Subsurface Transport Over Multiple Phases) simulator to predict flow patterns and solute transport behavior under these conditions. Unstable infiltration may, under certain conditions, create vertically elongated fingers potentially transporting contaminants rapidly through the unsaturated zone to groundwater. The types of leak that may create deeply penetrating fingers include slow release, long duration leaks in relatively permeable porous media. Such leaks may have occurred below waste tanks at the Hanford Site. •Large flow experiments to investigate the behavior of two types of tank leaks in a simple layered system mimicking the Waste Management Area C. The investigated leaks include a relatively large leak with a short duration from a tank and a long duration leak with a relatively small leakage rate from a cascade line.

  20. Assessment of Field Experience Related to Pressurized Water Reactor Primary System Leaks

    SciTech Connect

    Shah, Vikram Naginbhai; Ware, Arthur Gates; Atwood, Corwin Lee; Sattison, Martin Blaine; Hartley, Robert Scott; Hsu, C.

    1999-08-01

    This paper presents our assessment of field experience related to pressurized water reactor (PWR) primary system leaks in terms of their number of rates, how aging affects frequency of leak events, the safety significance of such leaks, industry efforts to reduce leaks, and effectiveness of current leak detection systems. We have reviewed the licensee event reports to identify the events that took place during 1985 to the third quarter of 1996, and reviewed related technical literature and visited PWR plants to analyze these events. Our assessment shows that USNRC licensees have taken effective actions to reduce the number of leak events. One main reason for this decreasing trend was the elimination or reportable leakages from valve stem packing after 1991. Our review of leak events related to vibratory fatigue reveals a statistically significant decreasing trend with age (years of operation), but not in calendar time. Our assessment of worldwide data on leakage caused by thermal fatigue cracking is that the fatigue of aging piping is a safety significant issue. Our review of leak events has identified several susceptible sites in piping having high safety significance; but the inspection of some of these sites is not required by the ASME Code. These sites may be included in the risk-informed inspection programs.

  1. Assessment of Field Experience Related to Pressurized Water Reactor Primary System Leaks

    SciTech Connect

    A. G. Ware; C. Hsu; C. L. Atwood; M. B. Sattison; R. S. Hartley; V. N. Shah

    1999-02-01

    This paper presents our assessment of field experience related to pressurized water reactor (PWR) primary system leaks in terms of their number and rates, how aging affects frequency of leak events, the safety significance of such leaks, industry efforts to reduce leaks, and effectiveness of current leak detection systems. We have reviewed the licensee event reports to identify the events that took place during 1985 to the third quarter of 1996, and reviewed related technical literature and visited PWR plants to analyze these events. Our assessment shows that USNRC licensees have taken effective actions to reduce the number of leak events. One main reason for this decreasing trend was the elimination or reportable leakages from valve stem packing after 1991. Our review of leak events related to vibratory fatigue reveals a statistically significant decreasing trend with age (years of operation), but not in calendar time. Our assessment of worldwide data on leakage caused by thermal fatigue cracking is that the fatigue of aging piping is a safety significant issue. Our review of leak events has identified several susceptible sites in piping having high safety significance; but the inspection of some of these sites is not required by the ASME Code. These sites may be included in the risk-informed inspection programs.

  2. Absolute rate constants for the quenching of reactive excited states by melanin and related 5,6-dihydroxyindole metabolites: implications for their antioxidant activity.

    PubMed

    Zhang, X; Erb, C; Flammer, J; Nau, W M

    2000-05-01

    The triplet-excited state of benzophenone and the singlet-excited state of 2,3-diazabicyclo[2.2.2]oct-2-ene (Fluorazophore-P) have been employed as kinetic probes to obtain information on the antioxidant activity of the skin and eye pigment melanin and its biogenetic precursors 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). The excited states were generated by the laser-flash photolysis technique and their reaction kinetics was examined by time-resolved transient absorption or fluorescence spectroscopy, respectively. The reaction between triplet benzophenone and DHI produced with unit efficiency the corresponding 6O-centered semiquinone radical, which was characterized by its characteristic transient absorption. The quenching rate constants for DHI (3.1-8.4 x 10(9) M-1 s-1) and DHICA (3.3-5.5 x 10(9) M-1 s-1) were near the diffusion-controlled limit, indicating excellent antioxidant properties. Kinetic solvent effects were observed. The reactivity of synthetic melanin, assessed through the quenching rate constant of Fluorazophore-P and normalized to the number of monomer units, was more than one order of magnitude lower (2.7 x 10(8) M-1 s-1) than that of its precursors. The trend of the quenching rate constants, i.e. DHI > DHICA approximately alpha-tocopherol > melanin, along with the preferential solubility of DHICA in aqueous environments, serves to account for several experimental results from biochemical studies on the inhibition of lipid peroxidation by these natural antioxidants.

  3. Neonatal air leak syndrome and the role of high-frequency ventilation in its prevention.

    PubMed

    Jeng, Mei-Jy; Lee, Yu-Sheng; Tsao, Pei-Chen; Soong, Wen-Jue

    2012-11-01

    Air leak syndrome includes pulmonary interstitial emphysema, pneumothorax, pneumomediastinum, pneumopericardium, pneumoperitoneum, subcutaneous emphysema, and systemic air embolism. The most common cause of air leak syndrome in neonates is inadequate mechanical ventilation of the fragile and immature lungs. The incidence of air leaks in newborns is inversely related to the birth weight of the infants, especially in very-low-birth-weight and meconium-aspirated infants. When the air leak is asymptomatic and the infant is not mechanically ventilated, there is usually no specific treatment. Emergent needle aspiration and/or tube drainage are necessary in managing tension pneumothorax or pneumopericardium with cardiac tamponade. To prevent air leak syndrome, gentle ventilation with low pressure, low tidal volume, low inspiratory time, high rate, and judicious use of positive end expiratory pressure are the keys to caring for mechanically ventilated infants. Both high-frequency oscillatory ventilation (HFOV) and high-frequency jet ventilation (HFJV) can provide adequate gas exchange using extremely low tidal volume and supraphysiologic rate in neonates with acute pulmonary dysfunction, and they are considered to have the potential to reduce the risks of air leak syndrome in neonates. However, there is still no conclusive evidence that HFOV or HFJV can help to reduce new air leaks in published neonatal clinical trials. In conclusion, neonatal air leaks may present as a thoracic emergency requiring emergent intervention. To prevent air leak syndrome, gentle ventilations are key to caring for ventilated infants. There is insufficient evidence showing the role of HFOV and HFJV in the prevention or reduction of new air leaks in newborn infants, so further investigation will be necessary for future applications.

  4. Absolute neutrino mass scale

    NASA Astrophysics Data System (ADS)

    Capelli, Silvia; Di Bari, Pasquale

    2013-04-01

    Neutrino oscillation experiments firmly established non-vanishing neutrino masses, a result that can be regarded as a strong motivation to extend the Standard Model. In spite of being the lightest massive particles, neutrinos likely represent an important bridge to new physics at very high energies and offer new opportunities to address some of the current cosmological puzzles, such as the matter-antimatter asymmetry of the Universe and Dark Matter. In this context, the determination of the absolute neutrino mass scale is a key issue within modern High Energy Physics. The talks in this parallel session well describe the current exciting experimental activity aiming to determining the absolute neutrino mass scale and offer an overview of a few models beyond the Standard Model that have been proposed in order to explain the neutrino masses giving a prediction for the absolute neutrino mass scale and solving the cosmological puzzles.

  5. Leaks in nuclear grade high efficiency aerosol filters

    SciTech Connect

    Scripsick, Ronald Clyde

    1994-07-01

    Nuclear grade high efficiency aerosol filters, also known as high efficiency particulate air (HEPA) filters, are commonly used in air cleaning systems for removal of hazardous aerosols. Performance of the filter units is important in assuring health and environmental protection. The filter units are constructed from pleated packs of fiberglass filter media sealed into rigid frames. Results of previous studies on such filter units indicate that their performance may not be completely predicted by ideal performance of the fibrous filter media. In this study, departure from ideal performance is linked to leaks existing in filter units and overall filter unit performance is derived from independent performance of the individual filter unit components. The performance of 14 nuclear grade HEPA filter units (size 1, 25 cfm) with plywood frames was evaluated with a test system that permitted independent determination of penetration as a function of particle size for the whole filter unit, the filter unit frame, and the filter media pack. Tests were performed using a polydisperse aerosol of di-2-ethylhexyl phthalate with a count median diameter of 0.2 {mu}m and geometric standard deviation of 1.6. Flow rate and differential pressure were controlled from 1% to 100% of design values. Particle counts were made upstream and downstream of the filter unit with an optical particle counter (OPC). The OPC provided count information in 28 size channels over the particle diameter range from 0.1 to 0.7 μm. Results provide evidence for a two component leak model of filler unit performance with: (1) external leaks through filter unit frames, and (2) internal leaks through defects in the media and through the seal between the media pack and frame. For the filter units evaluated, these leaks dominate overall filter unit performance over much of the flow rate and particle size ranges tested.

  6. Leak checker data logging system

    DOEpatents

    Gannon, J.C.; Payne, J.J.

    1996-09-03

    A portable, high speed, computer-based data logging system for field testing systems or components located some distance apart employs a plurality of spaced mass spectrometers and is particularly adapted for monitoring the vacuum integrity of a long string of a superconducting magnets such as used in high energy particle accelerators. The system provides precise tracking of a gas such as helium through the magnet string when the helium is released into the vacuum by monitoring the spaced mass spectrometers allowing for control, display and storage of various parameters involved with leak detection and localization. A system user can observe the flow of helium through the magnet string on a real-time basis hour the exact moment of opening of the helium input valve. Graph reading can be normalized to compensate for magnet sections that deplete vacuum faster than other sections between testing to permit repetitive testing of vacuum integrity in reduced time. 18 figs.

  7. Leak checker data logging system

    DOEpatents

    Gannon, Jeffrey C.; Payne, John J.

    1996-01-01

    A portable, high speed, computer-based data logging system for field testing systems or components located some distance apart employs a plurality of spaced mass spectrometers and is particularly adapted for monitoring the vacuum integrity of a long string of a superconducting magnets such as used in high energy particle accelerators. The system provides precise tracking of a gas such as helium through the magnet string when the helium is released into the vacuum by monitoring the spaced mass spectrometers allowing for control, display and storage of various parameters involved with leak detection and localization. A system user can observe the flow of helium through the magnet string on a real-time basis hour the exact moment of opening of the helium input valve. Graph reading can be normalized to compensate for magnet sections that deplete vacuum faster than other sections between testing to permit repetitive testing of vacuum integrity in reduced time.

  8. Protecting brazing furnaces from air leaks

    NASA Technical Reports Server (NTRS)

    Armenoff, C. T.; Mckown, R. D.

    1980-01-01

    Inexpensive inert-atmosphere shielding protects vacuum brazing-furnace components that are likely to spring leak. Pipefittings, gages, and valves are encased in transparent plastic shroud inflated with argon. If leak develops, harmless argon will enter vacuum chamber, making it possible to finish ongoing brazing or heat treatment before shutting down for repair.

  9. EPA Needs Leak Detectives in Texas

    EPA Pesticide Factsheets

    DALLAS - (March 15, 2016) Every year more than one trillion gallons of water are wasted by easy-to-fix household leaks. The U.S. Environmental Protection Agency (EPA) is encouraging consumers to Be a leak detective during WaterSense's eighth annua

  10. EPA Needs Leak Detectives in New Mexico

    EPA Pesticide Factsheets

    DALLAS - (March 15, 2016) Every year more than one trillion gallons of water are wasted by easy-to-fix household leaks. The U.S. Environmental Protection Agency (EPA) is encouraging consumers to Be a Leak Detective during WaterSense's eighth annua

  11. Kinetics of O(1D) + H2O and O(1D) + H2: absolute rate coefficients and O(3P) yields between 227 and 453 K.

    PubMed

    Vranckx, Stijn; Peeters, Jozef; Carl, Shaun

    2010-08-28

    The rate coefficients for the crucial atmospheric reactions of O((1)D) with H(2)O and H(2), k(1) and k(2), were measured over a wide temperature range using O((1)D) detection based on the chemiluminescence reaction of O((1)D) with C(2)H. Analyzing the decays of the chemiluminescence intensities yielded a value for k(1)(T) of (1.70 x 10(-10)exp[36 K/T]) cm(3) s(-1). Multiplying or dividing k(1)(T) by a factor f(T) = 1.04 exp(5.59(|1 K/T- 1/287|)), gives the 95% confidence limits; our new determination, in good agreement with previous studies, further reduces the uncertainty in k(1). An extended study of k(2) yielded a temperature independent rate constant of (1.35 +/- 0.05) x 10(-10) cm(3) s(-1). This precise value, based on an extended set of determinations with very low scatter, is significantly larger than the current recommendations, as were two other recent k(2) determinations. Secondly, the fractions of O((1)D) quenched to O((3)P) by H(2)O and H(2), k(1b)/k(1) and k(2b)/k(2), were precisely determined from fits to chemiluminescence decays. A temperature-independent value for k(1b)/k(1) of 0.010 +/- 0.003 was found. For the quenching fraction k(2b)/k(2) a value of 0.007 +/- 0.007 was obtained at room temperature. Both determinations are significantly smaller than values and upper limits from previous studies.

  12. The absolute path command

    SciTech Connect

    Moody, A.

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the absolute path to a relative directory from the current working directory.

  13. Leak detection for underground storage tanks

    SciTech Connect

    Durgin, P.B. ); Young, T.M.

    1993-01-01

    This symposium was held in New Orleans, Louisiana on January 29, 1992. The purpose of this conference was to provide a forum for exchange of state-of-the-art information on leak detection for underground storage tanks that leaked fuel. A widespread concern was protection of groundwater supplies from these leaking tanks. In some cases, the papers report on research that was conducted two or three years ago but has never been adequately directed to the underground storage tank leak-detection audience. In other cases, the papers report on the latest leak-detection research. The symposium was divided into four sessions that were entitled: Internal Monitoring; External Monitoring; Regulations and Standards; and Site and Risk Evaluation. Individual papers have been cataloged separately for inclusion in the appropriate data bases.

  14. Ultrasonic Detectors Safely Identify Dangerous, Costly Leaks

    NASA Technical Reports Server (NTRS)

    2013-01-01

    In 1990, NASA grounded its space shuttle fleet. The reason: leaks detected in the hydrogen fuel systems of the Space Shuttles Atlantis and Columbia. Unless the sources of the leaks could be identified and fixed, the shuttles would not be safe to fly. To help locate the existing leaks and check for others, Kennedy Space Center engineers used portable ultrasonic detectors to scan the fuel systems. As a gas or liquid escapes from a leak, the resulting turbulence creates ultrasonic noise, explains Gary Mohr, president of Elmsford, New York-based UE Systems Inc., a long-time leader in ultrasonic detector technologies. "In lay terms, the leak is like a dog whistle, and the detector is like the dog ear." Because the ultrasound emissions from a leak are highly localized, they can be used not only to identify the presence of a leak but also to help pinpoint a leak s location. The NASA engineers employed UE s detectors to examine the shuttle fuel tanks and solid rocket boosters, but encountered difficulty with the devices limited range-certain areas of the shuttle proved difficult or unsafe to scan up close. To remedy the problem, the engineers created a long-range attachment for the detectors, similar to "a zoom lens on a camera," Mohr says. "If you are on the ground, and the leak is 50 feet away, the detector would now give you the same impression as if you were only 25 feet away." The enhancement also had the effect of reducing background noise, allowing for a clearer, more precise detection of a leak s location.

  15. Viscous flow effects on hydrogen leaks from cracks in the Orbiter Challenger main engines

    NASA Technical Reports Server (NTRS)

    Goodrich, W. D.

    1984-01-01

    An analytical model was developed to provide additional insight and understanding of the factors that influence the simulation and prediction of leak rates from small cracks in pressurized containers. Specifically, the analysis was aimed at developing an analytical model capable of predicting the hydrogen leak rates from a crack in the combustion chamber coolant discharge manifold on main engine 1 of the Orbiter Challenger that was discovered during flight readiness firings 1 and 2. This model was based on viscous pipe flow analyses and calibrated for the crack geometry by using helium leak-rate data obtained from both low- and high-pressure tests used to simulate the flight readiness firing test conditions. In addition, this model includes the effects of crack width changes caused by different working stresses associated with the different test conditions. Because of the combination of the small crack dimensions and the wide range of pressures used for the test conditions, either laminar or turbulent viscous effects dominated the flows at all test conditions. This model was used to illustrate the sensitivity of the predicted leak rates to considerations of test conditions, viscous flow effects, and geometric features of the crack. In addition, the model was certified by comparing the hydrogen leak-rate prediction for the flight readiness firing test condition to the actual measured leak rate. The prediction was within 9 percent of the measured value.

  16. The International Space Station 2B Photovoltaic Thermal Control System (PVTCS) Leak: An Operational History

    NASA Technical Reports Server (NTRS)

    Vareha, Anthony N.

    2014-01-01

    As early as 2004, the Photovoltaic Thermal Control System (PVTCS) for the International Space Station's 2B electrical power channel began slowly leaking ammonia overboard. Initially, the operations strategy was "feed the leak," a strategy successfully put into action via Extra Vehicular Activity (EVA) during the STS-134 Space Shuttle mission. This recharge was to have allowed for continued power channel operation into 2014 or 2015, at which point another EVA would have been required. In mid-2012, the leak rate increased from 1.5lbm/year to approximately 5lbm/year. As a result, an EVA was planned and executed within a 5 week timeframe to drastically alter the architecture of the PVTCS via connection to an adjacent dormant thermal control system. This EVA, US EVA 20, was successfully executed on November 1, 2012 and left the 2B PVTCS in a configuration where the system was now being adequately cooled via a different radiator than what the system was designed to utilize. Data monitoring over the next several months showed that the isolated radiator had not been leaking, and the system itself continued to leak steadily until May 9th, 2013. It was on this day that the ISS crew noticed the visible presence of ammonia crystals escaping from the 2B channel's truss segment, signifying a rapid acceleration of the leak from 5lbm/year to 5lbm/day. Within 48 hours of the crew noticing the leak, US EVA 21 was in progress to replace the coolant pump - the only remaining replaceable leak source. This was successful, and telemetry monitoring has shown that indeed the coolant pump was the leak source and was thus isolated from the running 2B PVTCS. This paper will explore the management of the 2B PVTCS leak from the operations perspective.

  17. Demonstration of rapid and sensitive module leak certification for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Dietz, R. N.; Goodrich, R. W.

    1991-01-01

    A leak detection and quantification demonstration using perflurocarbon tracer (PFT) technology was successfully performed at the NASA Marshall Space Flight Center on January 25, 1991. The real-time Dual Trap Analyzer (DTA) at one-half hour after the start of the first run gave an estimated leak rate of 0.7 mL/min. This has since been refined to be 1.15 (+ or -) 0.09 mL/min. The leak rates in the next three runs were determined to be 9.8 (+ or -) 0.7, -0.4 (+ or -) 0.3, and 76 (+ or -) 6 mL/min, respectively. The theory on leak quantification in the steady-state and time-dependent modes for a single zone test facility was developed and applied to the above determinations. The laboratory PFT analysis system gave a limit-of-detection (LOD) of 0.05 fL for ocPDCH. This is the tracer of choice and is about 100-fold better than that for the DTA. Applied to leak certification, the LOD is about 0.00002 mL/s (0.000075 L/h), a 5 order-of-magnitude improvement over the original leak certification specification. Furthermore, this limit can be attained in a measurement period of 3 to 4 hours instead of days, weeks, or months. A new Leak Certification Facility is also proposed to provide for zonal (three zones) determination of leak rates. The appropriate multizone equations, their solutions, and error analysis have already been derived. A new concept of seal-integrity certification has been demonstrated for a variety of controlled leaks in the range of module leak testing. High structural integrity leaks were shown to have a linear dependence of flow on (Delta)p. The rapid determination of leak rates at different pressures is proposed and is to be determined while subjecting the module to other external force-generating parameters such as vibration, torque, solar intensity, etc.

  18. Precision blood-leak detector with high long-time stability

    NASA Astrophysics Data System (ADS)

    Georgiadis, Christos; Kleuver, Wolfram

    1999-11-01

    With this publication a precision blood-leak-detector is presented. The blood-leak-detector is used for recognition of fractures in the dialyzer of a kidney-machine. It has to detect safely a blood flow of ml/min to exclude any risk for the patient. A lot of systems exist for blood-leak-detection. All of them use the same principle. They detect the light absorption in the dialyze fluid. The actual used detectors are inferior to the new developed sensor in resolution and long-time stability. Regular test of the existing systems and high failure rates are responsible for the high maintenance.

  19. Demonstration of rapid and sensitive module leak certification for space station freedom

    SciTech Connect

    Dietz, R.N.; Goodrich, R.W. )

    1991-03-01

    A leak detection and quantification demonstration using perflurocarbon tracer (PFT) technology was successfully performed at the NASA Marshall Space Flight Center on January 25, 1991. The real-time Dual Trap Analyzer (DTA) at one-half hour after the start of the first run gave an estimated leak rate of 0.7 mL/min. This has since been refined to be 1.15 {plus minus} 0.09 mL/min. The leak rates in the next three runs were determined to be 9.8 {plus minus} 0.7, {minus}0.4 {plus minus} 0.3, and 76 {plus minus} 6 mL/min, respectively. The theory on leak quantification in the steady-state and time-dependent modes for a single zone test facility was developed and applied to the above determinations. The laboratory PFT analysis system gave a limit-of-detection (LOD) of 0.05 fL for ocPDCH. This is the tracer of choice and is about 100-fold better than that for the DTA. Applied to leak certification, the LOD is about 0.00002 mL/s (0.000075 L/h), a 5 order-of-magnitude improvement over the original leak certification specification. Furthermore, this limit can be attained in a measurement period of 3 to 4 hours instead of days, weeks, or months. A new Leak Certification Facility is also proposed to provide for zonal (three zones) determination of leak rates. The appropriate multizone equations, their solutions, and error analysis have already been derived. A new concept of seal-integrity certification has been demonstrated for a variety of controlled leaks in the range of module leak testing. High structural integrity leaks were shown to have a linear dependence of flow on {Delta}p. The rapid determination of leak rates at different pressures is proposed and is to be determined while subjecting the module to other external force-generating parameters such as vibration, torque, solar intensity, etc. 13 refs.

  20. Demonstration of rapid and sensitive module leak certification for space station freedom. Final report

    SciTech Connect

    Dietz, R.N.; Goodrich, R.W.

    1991-03-01

    A leak detection and quantification demonstration using perflurocarbon tracer (PFT) technology was successfully performed at the NASA Marshall Space Flight Center on January 25, 1991. The real-time Dual Trap Analyzer (DTA) at one-half hour after the start of the first run gave an estimated leak rate of 0.7 mL/min. This has since been refined to be 1.15 {plus_minus} 0.09 mL/min. The leak rates in the next three runs were determined to be 9.8 {plus_minus} 0.7, {minus}0.4 {plus_minus} 0.3, and 76 {plus_minus} 6 mL/min, respectively. The theory on leak quantification in the steady-state and time-dependent modes for a single zone test facility was developed and applied to the above determinations. The laboratory PFT analysis system gave a limit-of-detection (LOD) of 0.05 fL for ocPDCH. This is the tracer of choice and is about 100-fold better than that for the DTA. Applied to leak certification, the LOD is about 0.00002 mL/s (0.000075 L/h), a 5 order-of-magnitude improvement over the original leak certification specification. Furthermore, this limit can be attained in a measurement period of 3 to 4 hours instead of days, weeks, or months. A new Leak Certification Facility is also proposed to provide for zonal (three zones) determination of leak rates. The appropriate multizone equations, their solutions, and error analysis have already been derived. A new concept of seal-integrity certification has been demonstrated for a variety of controlled leaks in the range of module leak testing. High structural integrity leaks were shown to have a linear dependence of flow on {Delta}p. The rapid determination of leak rates at different pressures is proposed and is to be determined while subjecting the module to other external force-generating parameters such as vibration, torque, solar intensity, etc. 13 refs.

  1. Leak Detection by Acoustic Emission Monitoring. Phase 1. Feasibility Study

    DTIC Science & Technology

    1994-05-26

    considered the soil composition- and structure , the leak depth and rate, the acoustic array geometry on the 12 PHASE I 03 SflAIASTrNAflc C’ 111 ATON 90111...First Conference on Acoustic Emission/ Microseismic Activilty in Geologic Structures and Materials. H.R. Hardy, Jr. and F.W. Leighton, 2ditors. Trans...Recognition and Acoustical Imaging , Newport Beach, California, February 4-6. 1987. 29. M.C. Junger and D. Feit. Sounds, Structures , and Their Interaction, The

  2. Nitrogen leak test of Strategic Petroleum Reserve Cavern Bayou Choctaw 2

    SciTech Connect

    Goin, K.L.

    1983-10-01

    A nitrogen leak test was made of the Strategic Petroleum Reserve Bayou Choctaw Cavern 2. Results of the test are inadequate for estimating the cavern leak rate with a high level of confidence. The interpretation of test results believed to be the most reasonable indicates an average nitrogen loss rate of 300 bbls/yr with an 84-percent probability the loss rate does not exceed 1950 bbls/yr. With maximum oil loss rates estimated at one third of nitrogen volume loss rates, corresponding oil loss rates are 100 and 650 bbls/yr. 3 references, 8 figures.

  3. An improved PCA method with application to boiler leak detection.

    PubMed

    Sun, Xi; Marquez, Horacio J; Chen, Tongwen; Riaz, Muhammad

    2005-07-01

    Principal component analysis (PCA) is a popular fault detection technique. It has been widely used in process industries, especially in the chemical industry. In industrial applications, achieving a sensitive system capable of detecting incipient faults, which maintains the false alarm rate to a minimum, is a crucial issue. Although a lot of research has been focused on these issues for PCA-based fault detection and diagnosis methods, sensitivity of the fault detection scheme versus false alarm rate continues to be an important issue. In this paper, an improved PCA method is proposed to address this problem. In this method, a new data preprocessing scheme and a new fault detection scheme designed for Hotelling's T2 as well as the squared prediction error are developed. A dynamic PCA model is also developed for boiler leak detection. This new method is applied to boiler water/steam leak detection with real data from Syncrude Canada's utility plant in Fort McMurray, Canada. Our results demonstrate that the proposed method can effectively reduce false alarm rate, provide effective and correct leak alarms, and give early warning to operators.

  4. Vacuum leak detection for double bottom tanks

    SciTech Connect

    Hagen, T.; Rials, R.

    1995-12-31

    Double bottom tanks offer strong leak detection advantages. By incorporating the use of vacuum detection between the two bottoms, the tank bottoms can be verified leak free after construction and during tank use. Utilizing vacuum leak detection requires special considerations. In 1992 a tank construction company built 10 tanks for an oil company in Ponca City, Oklahoma. Each of these tanks were built with a double bottom. This paper provides insight into the planning, construction and testing of this type of double bottom design.

  5. Environmental policy -- A leaking drum?

    SciTech Connect

    Bishop, J.

    1995-07-01

    Twenty years ago, the US had virtually no overall environmental policy. Since then, one has evolved as a result of accumulated legislation, much of which was crafted in reaction to specific events, typically real or potential disasters. The familiar names of Love Canal, Times Beach, Bhopal and others are the symbolic anchor points of that evolution, which yielded Superfund, the Resource Conservation and Recovery Act, the Superfund Amendments and Reauthorization Act, and other environmental statutes. The laws in each case were developed in response to particular environmental and health issues--clean water for drinking and recreation, unpolluted air, safe production of chemicals and chemical-based products. The result was a growing body of environmental legislation that eventually became an accumulate of requirements lacking internal consistency or coherence. Because policymaking followed, rather than guided, legislative actions, the policy itself became inconsistent and sometimes illogical. Like a drum that gradually and indiscriminately is filled with a mixture of mutually reactive chemicals, environmental policy increasingly became a volatile source of concern for those industries in whose midst it had been placed. Lately, there is growing consensus that the drum not only has been overfilled, it also is leaking.

  6. Analytical and experimental studies of leak location and environment characterization for the international space station

    NASA Astrophysics Data System (ADS)

    Woronowicz, Michael; Abel, Joshua; Autrey, David; Blackmon, Rebecca; Bond, Tim; Brown, Martin; Buffington, Jesse; Cheng, Edward; DeLatte, Danielle; Garcia, Kelvin; Glenn, Jodie; Hawk, Doug; Ma, Jonathan; Mohammed, Jelila; de Garcia, Kristina Montt; Perry, Radford; Rossetti, Dino; Tull, Kimathi; Warren, Eric

    2014-12-01

    The International Space Station program is developing a robotically-operated leak locator tool to be used externally. The tool would consist of a Residual Gas Analyzer for partial pressure measurements and a full range pressure gauge for total pressure measurements. The primary application is to demonstrate the ability to detect NH3 coolant leaks in the ISS thermal control system. An analytical model of leak plume physics is presented that can account for effusive flow as well as plumes produced by sonic orifices and thruster operations. This model is used along with knowledge of typical RGA and full range gauge performance to analyze the expected instrument sensitivity to ISS leaks of various sizes and relative locations ("directionality"). The paper also presents experimental results of leak simulation testing in a large thermal vacuum chamber at NASA Goddard Space Flight Center. This test characterized instrument sensitivity as a function of leak rates ranging from 1 lbm//yr. to about 1 lbm/day. This data may represent the first measurements collected by an RGA or ion gauge system monitoring off-axis point sources as a function of location and orientation. Test results are compared to the analytical model and used to propose strategies for on-orbit leak location and environment characterization using the proposed instrument while taking into account local ISS conditions and the effects of ram/wake flows and structural shadowing within low Earth orbit.

  7. Analytical and Experimental Studies of Leak Location and Environment Characterization for the International Space Station

    NASA Technical Reports Server (NTRS)

    Woronowicz, Michael; Abel, Joshua; Autrey, David; Blackmon, Rebecca; Bond, Tim; Brown, Martin; Buffington, Jesse; Cheng, Edward; DeLatte, Danielle; Garcia, Kelvin; Glenn, Jodie; Hawk, Doug; Ma, Jonathan; Mohammed, Jelila; Montt de Garcia, Kristina; Perry, Radford; Rossetti, Dino; Tull, Kimathi; Warren, Eric

    2014-01-01

    The International Space Station program is developing a robotically-operated leak locator tool to be used externally. The tool would consist of a Residual Gas Analyzer for partial pressure measurements and a full range pressure gauge for total pressure measurements. The primary application is to detect NH3 coolant leaks in the ISS thermal control system. An analytical model of leak plume physics is presented that can account for effusive flow as well as plumes produced by sonic orifices and thruster operations. This model is used along with knowledge of typical RGA and full range gauge performance to analyze the expected instrument sensitivity to ISS leaks of various sizes and relative locations ("directionality"). The paper also presents experimental results of leak simulation testing in a large thermal vacuum chamber at NASA Goddard Space Flight Center. This test characterized instrument sensitivity as a function of leak rates ranging from 1 lb-mass/yr. to about 1 lb-mass/day. This data may represent the first measurements collected by an RGA or ion gauge system monitoring off-axis point sources as a function of location and orientation. Test results are compared to the analytical model and used to propose strategies for on-orbit leak location and environment characterization using the proposed instrument while taking into account local ISS conditions and the effects of ram/wake flows and structural shadowing within low Earth orbit.

  8. Analytical and experimental studies of leak location and environment characterization for the international space station

    SciTech Connect

    Woronowicz, Michael; Blackmon, Rebecca; Brown, Martin; Abel, Joshua; Hawk, Doug; Autrey, David; Glenn, Jodie; Bond, Tim; Buffington, Jesse; Cheng, Edward; Ma, Jonathan; Rossetti, Dino; DeLatte, Danielle; Garcia, Kelvin; Mohammed, Jelila; Montt de Garcia, Kristina; Perry, Radford; Tull, Kimathi; Warren, Eric

    2014-12-09

    The International Space Station program is developing a robotically-operated leak locator tool to be used externally. The tool would consist of a Residual Gas Analyzer for partial pressure measurements and a full range pressure gauge for total pressure measurements. The primary application is to demonstrate the ability to detect NH{sub 3} coolant leaks in the ISS thermal control system. An analytical model of leak plume physics is presented that can account for effusive flow as well as plumes produced by sonic orifices and thruster operations. This model is used along with knowledge of typical RGA and full range gauge performance to analyze the expected instrument sensitivity to ISS leaks of various sizes and relative locations (“directionality”). The paper also presents experimental results of leak simulation testing in a large thermal vacuum chamber at NASA Goddard Space Flight Center. This test characterized instrument sensitivity as a function of leak rates ranging from 1 lb{sub m/}/yr. to about 1 lb{sub m}/day. This data may represent the first measurements collected by an RGA or ion gauge system monitoring off-axis point sources as a function of location and orientation. Test results are compared to the analytical model and used to propose strategies for on-orbit leak location and environment characterization using the proposed instrument while taking into account local ISS conditions and the effects of ram/wake flows and structural shadowing within low Earth orbit.

  9. High sensitivity of spontaneous spike frequency to sodium leak current in a Lymnaea pacemaker neuron.

    PubMed

    Lu, T Z; Kostelecki, W; Sun, C L F; Dong, N; Pérez Velázquez, J L; Feng, Z-P

    2016-12-01

    The spontaneous rhythmic firing of action potentials in pacemaker neurons depends on the biophysical properties of voltage-gated ion channels and background leak currents. The background leak current includes a large K(+) and a small Na(+) component. We previously reported that a Na(+) -leak current via U-type channels is required to generate spontaneous action potential firing in the identified respiratory pacemaker neuron, RPeD1, in the freshwater pond snail Lymnaea stagnalis. We further investigated the functional significance of the background Na(+) current in rhythmic spiking of RPeD1 neurons. Whole-cell patch-clamp recording and computational modeling approaches were carried out in isolated RPeD1 neurons. The whole-cell current of the major ion channel components in RPeD1 neurons were characterized, and a conductance-based computational model of the rhythmic pacemaker activity was simulated with the experimental measurements. We found that the spiking rate is more sensitive to changes in the Na(+) leak current as compared to the K(+) leak current, suggesting a robust function of Na(+) leak current in regulating spontaneous neuronal firing activity. Our study provides new insight into our current understanding of the role of Na(+) leak current in intrinsic properties of pacemaker neurons.

  10. Analytical and Experimental Studies of Leak Location and Environment Characterization for the International Space Station

    NASA Technical Reports Server (NTRS)

    Woronowicz, Michael S.; Abel, Joshua C.; Autrey, David; Blackmon, Rebecca; Bond, Tim; Brown, Martin; Buffington, Jesse; Cheng, Edward; DeLatte, Danielle; Garcia, Kelvin; Glenn, Jodie; Hawk, Doug; Ma, Jonathan; Mohammed, Jelila; de Garcia, Kristina Montt; Perry, Radford; Rossetti, Dino; Tull, Kimathi; Warren, Eric

    2014-01-01

    The International Space Station program is developing a robotically-operated leak locator tool to be used externally. The tool would consist of a Residual Gas Analyzer for partial pressure measurements and a full range pressure gauge for total pressure measurements. The primary application is to detect NH3 coolant leaks in the ISS thermal control system.An analytical model of leak plume physics is presented that can account for effusive flow as well as plumes produced by sonic orifices and thruster operations. This model is used along with knowledge of typical RGA and full range gauge performance to analyze the expected instrument sensitivity to ISS leaks of various sizes and relative locations (directionality).The paper also presents experimental results of leak simulation testing in a large thermal vacuum chamber at NASA Goddard Space Flight Center. This test characterized instrument sensitivity as a function of leak rates ranging from 1 lbmyr. to about 1 lbmday. This data may represent the first measurements collected by an RGA or ion gauge system monitoring off-axis point sources as a function of location and orientation. Test results are compared to the analytical model and used to propose strategies for on-orbit leak location and environment characterization using the proposed instrument while taking into account local ISS conditions and the effects of ramwake flows and structural shadowing within low Earth orbit.

  11. Leaking Underground Storage Tank (LUST) Trust Fund

    EPA Pesticide Factsheets

    In 1986, Congress created the Leaking Underground Storage Tank (LUST) Trust Fund to address releases from federally regulated underground storage tanks (USTs) by amending Subtitle I of the Solid Waste Disposal Act.

  12. Leak Detectives Saving Money, Water in Virginia

    EPA Pesticide Factsheets

    “Circuit riders” from the Virginia Rural Water Association (VRWA) are traveling to small communities across the Commonwealth using special equipment financed by EPA to locate expensive and wasteful leaks in drinking water distribution systems.

  13. mpileaks - an MPI opject leak debugging library

    SciTech Connect

    Leon, E. A.

    2011-11-14

    The mpileaks tool is to be used by MPI application developers to track and report leaked MPI objects, such as requests, groups, and datatypes. This debugging tool is useful as a quality assurance check for MPI applications, or it can be used to identify leaks fatal to long-running MPI applications. It provides an efficient method to report bugs that are otherwise fifficult to identify.

  14. Leak detection in pipelines using cepstrum analysis

    NASA Astrophysics Data System (ADS)

    Taghvaei, M.; Beck, S. B. M.; Staszewski, W. J.

    2006-02-01

    The detection and location of leaks in pipeline networks is a major problem and the reduction of these leaks has become a major priority for pipeline authorities around the world. Although the reasons for these leaks are well known, some of the current methods for locating and identifying them are either complicated or imprecise; most of them are time consuming. The work described here shows that cepstrum analysis is a viable approach to leak detection and location in pipeline networks. The method uses pressure waves caused by quickly opening and closing a solenoid valve. Due to their simplicity and robustness, transient analyses provide a plausible route towards leak detection. For this work, the time domain signals of these pressure transients were obtained using a single pressure transducer. These pressure signals were first filtered using discrete wavelets to remove the dc offset, and the low and high frequencies. They were then analysed using a cepstrum method which identified the time delay between the initial wave and its reflections. There were some features in the processed results which can be ascribed to features in the pipeline network such as junctions and pipe ends. When holes were drilled in the pipe, new peaks occurred which identified the presence of a leak in the pipeline network. When tested with holes of different sizes, the amplitude of the processed peak was seen to increase as the cube root of the leak diameter. Using this method, it is possible to identify leaks that are difficult to find by other methods as they are small in comparison with the flow through the pipe.

  15. Modeling Leaking Gas Plume Migration

    SciTech Connect

    Silin, Dmitriy; Patzek, Tad; Benson, Sally M.

    2007-08-20

    In this study, we obtain simple estimates of 1-D plume propagation velocity taking into account the density and viscosity contrast between CO{sub 2} and brine. Application of the Buckley-Leverett model to describe buoyancy-driven countercurrent flow of two immiscible phases leads to a transparent theory predicting the evolution of the plume. We obtain that the plume does not migrate upward like a gas bubble in bulk water. Rather, it stretches upward until it reaches a seal or until the fluids become immobile. A simple formula requiring no complex numerical calculations describes the velocity of plume propagation. This solution is a simplification of a more comprehensive theory of countercurrent plume migration that does not lend itself to a simple analytical solution (Silin et al., 2006). The range of applicability of the simplified solution is assessed and provided. This work is motivated by the growing interest in injecting carbon dioxide into deep geological formations as a means of avoiding its atmospheric emissions and consequent global warming. One of the potential problems associated with the geologic method of sequestration is leakage of CO{sub 2} from the underground storage reservoir into sources of drinking water. Ideally, the injected green-house gases will stay in the injection zone for a geologically long time and eventually will dissolve in the formation brine and remain trapped by mineralization. However, naturally present or inadvertently created conduits in the cap rock may result in a gas leak from primary storage. Even in supercritical state, the carbon dioxide viscosity and density are lower than those of the indigenous formation brine. Therefore, buoyancy will tend to drive the CO{sub 2} upward unless it is trapped beneath a low permeability seal. Theoretical and experimental studies of buoyancy-driven supercritical CO{sub 2} flow, including estimation of time scales associated with plume evolution, are critical for developing technology

  16. Preliminary study of the use of radiotracers for leak detection in industrial applications

    NASA Astrophysics Data System (ADS)

    Wetchagarun, S.; Petchrak, A.; Tippayakul, C.

    2015-05-01

    One of the most widespread uses of radiotracers in the industrial applications is the leak detection of the systems. This technique can be applied, for example, to detect leak in heat exchangers or along buried industrial pipelines. The ability to perform online investigation is one of the most important advantages of the radiotracer technique over other non-radioactive leak detection methods. In this paper, a preliminary study of the leak detection using radiotracer in the laboratory scale was presented. Br-82 was selected for this work due to its chemical property, its suitable half-life and its on-site availability. The NH4Br in the form of aqueous solution was injected into the experimental system as the radiotracer. Three NaI detectors were placed along the pipelines to measure system flow rate and to detect the leakage from the piping system. The results obtained from the radiotracer technique were compared to those measured by other methods. It is found that the flow rate obtained from the radiotracer technique agreed well with the one obtained from the flow meter. The leak rate result, however, showed discrepancy between results obtained from two different measuring methods indicating further study on leak detection was required before applying this technique in the industrial system.

  17. Automated Hydrogen Gas Leak Detection System

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Gencorp Aerojet Automated Hydrogen Gas Leak Detection System was developed through the cooperation of industry, academia, and the Government. Although the original purpose of the system was to detect leaks in the main engine of the space shuttle while on the launch pad, it also has significant commercial potential in applications for which there are no existing commercial systems. With high sensitivity, the system can detect hydrogen leaks at low concentrations in inert environments. The sensors are integrated with hardware and software to form a complete system. Several of these systems have already been purchased for use on the Ford Motor Company assembly line for natural gas vehicles. This system to detect trace hydrogen gas leaks from pressurized systems consists of a microprocessor-based control unit that operates a network of sensors. The sensors can be deployed around pipes, connectors, flanges, and tanks of pressurized systems where leaks may occur. The control unit monitors the sensors and provides the operator with a visual representation of the magnitude and locations of the leak as a function of time. The system can be customized to fit the user's needs; for example, it can monitor and display the condition of the flanges and fittings associated with the tank of a natural gas vehicle.

  18. Leak Path Development in CO2 Wells

    NASA Astrophysics Data System (ADS)

    Torsater, M.; Todorovic, J.; Opedal, N.; Lavrov, A.

    2014-12-01

    Wells have in numerous scientific works been denoted the "weak link" of safe and cost-efficient CO2 Capture and Storage (CCS). Whether they are active or abandoned, all wells are man-made intrusions into the storage reservoir with sealing abilities depending on degradable materials like steel and cement. If dense CO2 is allowed to expand (e.g. due to leakage) it will cool down its surroundings and cause strong thermal and mechanical loading on the wellbore. In addition, CO2 reacts chemically with rock, cement and steel. To ensure long-term underground containment, it is therefore necessary to study how, why, where and when leakage occurs along CO2wells. If cement bonding to rock or casing is poor, leak paths can form already during drilling and completion of the well. In the present work, we have mapped the bonding quality of cement-rock and cement-steel interfaces - and measured their resistance towards CO2 flow. This involved a large experimental matrix including different rocks, steels, cement types and well fluids. The bonding qualities were measured on composite cores using micro computed tomography (µ-CT), and CO2 was flooded through the samples to determine leakage rates. These were further compared to numerical simulations of leakage through the digitalized µ-CT core data, and CO2chemical interactions with the materials were mapped using electron microscopy. We also present a new laboratory set-up for measuring how well integrity is affected by downhole temperature variations - and we showcase some initial results. Our work concludes that leak path development in CO2 wells depends critically on the drilling fluids and presflushes/spacers chosen already during drilling and completion of a well. Fluid films residing on rock and casing surfaces strongly degrade the quality of cement bonding. The operation of the well is also important, as even slight thermal cycling (between 10°C and 95°C on casing) leads to significant de-bonding of the annular cement.

  19. Electronic Absolute Cartesian Autocollimator

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.

    2006-01-01

    An electronic absolute Cartesian autocollimator performs the same basic optical function as does a conventional all-optical or a conventional electronic autocollimator but differs in the nature of its optical target and the manner in which the position of the image of the target is measured. The term absolute in the name of this apparatus reflects the nature of the position measurement, which, unlike in a conventional electronic autocollimator, is based absolutely on the position of the image rather than on an assumed proportionality between the position and the levels of processed analog electronic signals. The term Cartesian in the name of this apparatus reflects the nature of its optical target. Figure 1 depicts the electronic functional blocks of an electronic absolute Cartesian autocollimator along with its basic optical layout, which is the same as that of a conventional autocollimator. Referring first to the optical layout and functions only, this or any autocollimator is used to measure the compound angular deviation of a flat datum mirror with respect to the optical axis of the autocollimator itself. The optical components include an illuminated target, a beam splitter, an objective or collimating lens, and a viewer or detector (described in more detail below) at a viewing plane. The target and the viewing planes are focal planes of the lens. Target light reflected by the datum mirror is imaged on the viewing plane at unit magnification by the collimating lens. If the normal to the datum mirror is parallel to the optical axis of the autocollimator, then the target image is centered on the viewing plane. Any angular deviation of the normal from the optical axis manifests itself as a lateral displacement of the target image from the center. The magnitude of the displacement is proportional to the focal length and to the magnitude (assumed to be small) of the angular deviation. The direction of the displacement is perpendicular to the axis about which the

  20. Absolute airborne gravimetry

    NASA Astrophysics Data System (ADS)

    Baumann, Henri

    This work consists of a feasibility study of a first stage prototype airborne absolute gravimeter system. In contrast to relative systems, which are using spring gravimeters, the measurements acquired by absolute systems are uncorrelated and the instrument is not suffering from problems like instrumental drift, frequency response of the spring and possible variation of the calibration factor. The major problem we had to resolve were to reduce the influence of the non-gravitational accelerations included in the measurements. We studied two different approaches to resolve it: direct mechanical filtering, and post-processing digital compensation. The first part of the work describes in detail the different mechanical passive filters of vibrations, which were studied and tested in the laboratory and later in a small truck in movement. For these tests as well as for the airborne measurements an absolute gravimeter FG5-L from Micro-G Ltd was used together with an Inertial navigation system Litton-200, a vertical accelerometer EpiSensor, and GPS receivers for positioning. These tests showed that only the use of an optical table gives acceptable results. However, it is unable to compensate for the effects of the accelerations of the drag free chamber. The second part describes the strategy of the data processing. It is based on modeling the perturbing accelerations by means of GPS, EpiSensor and INS data. In the third part the airborne experiment is described in detail, from the mounting in the aircraft and data processing to the different problems encountered during the evaluation of the quality and accuracy of the results. In the part of data processing the different steps conducted from the raw apparent gravity data and the trajectories to the estimation of the true gravity are explained. A comparison between the estimated airborne data and those obtained by ground upward continuation at flight altitude allows to state that airborne absolute gravimetry is feasible and

  1. Risk factors for postoperative cerebrospinal fluid leak and meningitis after expanded endoscopic endonasal surgery.

    PubMed

    Ivan, Michael E; Iorgulescu, J Bryan; El-Sayed, Ivan; McDermott, Michael W; Parsa, Andrew T; Pletcher, Steven D; Jahangiri, Arman; Wagner, Jeffrey; Aghi, Manish K

    2015-01-01

    Postoperative cerebrospinal fluid (CSF) leak is a serious complication of transsphenoidal surgery, which can lead to meningitis and often requires reparative surgery. We sought to identify preoperative risk factors for CSF leaks and meningitis. We reviewed 98 consecutive expanded endoscopic endonasal surgeries performed from 2008-2012 and analyzed preoperative comorbidities, intraoperative techniques, and postoperative care. Univariate and multivariate analyses were performed. The most common pathologies addressed included pituitary adenoma, Rathke cyst, chordoma, esthesioneuroblastoma, meningioma, nasopharyngeal carcinoma, and squamous cell carcinoma. There were 11 CSF leaks (11%) and 10 central nervous system (CNS) infections (10%). Univariate and multivariate analysis of preoperative risk factors showed that patients with non-ideal body mass index (BMI) were associated with higher rate of postoperative CSF leak and meningitis (both p<0.01). Also, patients with increasing age were associated with increased CSF leak (p = 0.03) and the length of time a lumbar drain was used postoperatively was associated with infection in a univariate analysis. In addition, three of three endoscopic transsphenoidal surgeries combined with open cranial surgery had a postoperative CSF leak and CNS infection rate which was a considerably higher rate than for transsphenoidal surgeries alone or surgeries staged with open cases (p<0.01 and p=0.04, respectively) In this series of expanded endoscopic transsphenoidal surgeries, preoperative BMI remains the most important preoperative predictor for CSF leak and infection. Other risk factors include age, intraoperative CSF leak, lumbar drain duration, and cranial combined cases. Risks associated with complex surgical resections when combining open and endoscopic approaches could be minimized by staging these procedures.

  2. Absolute-structure reports.

    PubMed

    Flack, Howard D

    2013-08-01

    All the 139 noncentrosymmetric crystal structures published in Acta Crystallographica Section C between January 2011 and November 2012 inclusive have been used as the basis of a detailed study of the reporting of absolute structure. These structure determinations cover a wide range of space groups, chemical composition and resonant-scattering contribution. Defining A and D as the average and difference of the intensities of Friedel opposites, their level of fit has been examined using 2AD and selected-D plots. It was found, regardless of the expected resonant-scattering contribution to Friedel opposites, that the Friedel-difference intensities are often dominated by random uncertainty and systematic error. An analysis of data collection strategy is provided. It is found that crystal-structure determinations resulting in a Flack parameter close to 0.5 may not necessarily be from crystals twinned by inversion. Friedifstat is shown to be a robust estimator of the resonant-scattering contribution to Friedel opposites, very little affected by the particular space group of a structure nor by the occupation of special positions. There is considerable confusion in the text of papers presenting achiral noncentrosymmetric crystal structures. Recommendations are provided for the optimal way of treating noncentrosymmetric crystal structures for which the experimenter has no interest in determining the absolute structure.

  3. AIRBORNE, OPTICAL REMOTE SENSNG OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION

    SciTech Connect

    Jerry Myers

    2005-04-15

    Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. The scope of the work involved designing and developing an airborne, optical remote sensor capable of sensing methane and, if possible, ethane for the detection of natural gas pipeline leaks. Flight testing using a custom dual wavelength, high power fiber amplifier was initiated in February 2005. Ophir successfully demonstrated the airborne system, showing that it was capable of discerning small amounts of methane from a simulated pipeline leak. Leak rates as low as 150 standard cubic feet per hour (scf/h) were detected by the airborne sensor.

  4. EPA Chases Leaks in Arkansas during Seventh Annual Fix a Leak Week

    EPA Pesticide Factsheets

    Central Arkansas Water is offering free leak repairs and rain gauges to low-income or elderly customers throughout Little Rock and North Little Rock. They will also giveaway promotional items such as low-flow showerheads, faucet aerators and toilet leak de

  5. High-sensitivity Leak-testing Method with High-Resolution Integration Technique

    NASA Astrophysics Data System (ADS)

    Fujiyoshi, Motohiro; Nonomura, Yutaka; Senda, Hidemi

    A high-resolution leak-testing method named HR (High-Resolution) Integration Technique has been developed for MEMS (Micro Electro Mechanical Systems) sensors such as a vibrating angular-rate sensor housed in a vacuum package. Procedures of the method to obtain high leak-rate resolution were as follows. A package filled with helium gas was kept in a small accumulation chamber to accumulate helium gas leaking from the package. After the accumulation, the accumulated helium gas was introduced into a mass spectrometer in a short period of time, and the flux of the helium gas was measured by the mass spectrometer as a transient phenomenon. The leak-rate of the package was calculated from the detected transient waveform of the mass spectrometer and the accumulation time of the helium gas in the accumulation chamber. Because the density of the helium gas in the vacuum chamber increased and the accumulated helium gas was measured in a very short period of time with the mass spectrometer, the peak strength of the transient waveform became high and the signal to noise ratio was much improved. The detectable leak-rate resolution of the technique reached 1×10-15 (Pa·m3/s). This resolution is 103 times superior to that of the conventional helium vacuum integration method. The accuracy of the measuring system was verified with a standard helium gas leak source. The results were well matched between theoretical calculation based on the leak-rate of the source and the experimental results within only 2% error.

  6. Absolute Equilibrium Entropy

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    1997-01-01

    The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

  7. Operational Philosophy Concerning Manned Spacecraft Cabin Leaks

    NASA Technical Reports Server (NTRS)

    DeSimpelaere, Edward

    2011-01-01

    The last thirty years have seen the Space Shuttle as the prime United States spacecraft for manned spaceflight missions. Many lessons have been learned about spacecraft design and operation throughout these years. Over the next few decades, a large increase of manned spaceflight in the commercial sector is expected. This will result in the exposure of commercial crews and passengers to many of the same risks crews of the Space Shuttle have encountered. One of the more dire situations that can be encountered is the loss of pressure in the habitable volume of the spacecraft during on orbit operations. This is referred to as a cabin leak. This paper seeks to establish a general cabin leak response philosophy with the intent of educating future spacecraft designers and operators. After establishing a relative definition for a cabin leak, the paper covers general descriptions of detection equipment, detection methods, and general operational methods for management of a cabin leak. Subsequently, all these items are addressed from the perspective of the Space Shuttle Program, as this will be of the most value to future spacecraft due to similar operating profiles. Emphasis here is placed upon why and how these methods and philosophies have evolved to meet the Space Shuttle s needs. This includes the core ideas of: considerations of maintaining higher cabin pressures vs. lower cabin pressures, the pros and cons of a system designed to feed the leak with gas from pressurized tanks vs. using pressure suits to protect against lower cabin pressures, timeline and consumables constraints, re-entry considerations with leaks of unknown origin, and the impact the International Space Station (ISS) has had to the standard Space Shuttle cabin leak response philosophy. This last item in itself includes: procedural management differences, hardware considerations, additional capabilities due to the presence of the ISS and its resource, and ISS docking/undocking considerations with a

  8. Absolute multilateration between spheres

    NASA Astrophysics Data System (ADS)

    Muelaner, Jody; Wadsworth, William; Azini, Maria; Mullineux, Glen; Hughes, Ben; Reichold, Armin

    2017-04-01

    Environmental effects typically limit the accuracy of large scale coordinate measurements in applications such as aircraft production and particle accelerator alignment. This paper presents an initial design for a novel measurement technique with analysis and simulation showing that that it could overcome the environmental limitations to provide a step change in large scale coordinate measurement accuracy. Referred to as absolute multilateration between spheres (AMS), it involves using absolute distance interferometry to directly measure the distances between pairs of plain steel spheres. A large portion of each sphere remains accessible as a reference datum, while the laser path can be shielded from environmental disturbances. As a single scale bar this can provide accurate scale information to be used for instrument verification or network measurement scaling. Since spheres can be simultaneously measured from multiple directions, it also allows highly accurate multilateration-based coordinate measurements to act as a large scale datum structure for localized measurements, or to be integrated within assembly tooling, coordinate measurement machines or robotic machinery. Analysis and simulation show that AMS can be self-aligned to achieve a theoretical combined standard uncertainty for the independent uncertainties of an individual 1 m scale bar of approximately 0.49 µm. It is also shown that combined with a 1 µm m‑1 standard uncertainty in the central reference system this could result in coordinate standard uncertainty magnitudes of 42 µm over a slender 1 m by 20 m network. This would be a sufficient step change in accuracy to enable next generation aerospace structures with natural laminar flow and part-to-part interchangeability.

  9. ICPP water inventory study leak test report

    SciTech Connect

    Richards, B.T.

    1993-12-01

    Data from the Idaho Chemical Processing Plant (ICPP) indicate that there are three areas where perched water bodies (groundwater) are suspect to exist beneath the ICPP. Questions have been raised concerning the recharge sources for the northwest (NW) perched water body which is located below the northwest area of the ICPP. In response to these questions, a Water Inventory Study was initiated to determine the extent and the potential impacts of the ICPP water systems as a recharge source. A key part of the Water Inventory Study was the leak test investigation, performed to leak test the ICPP water piping distribution system, or portions thereof, which could potentially contribute to the recharge of the NW perched water body. This report provides an overview and the results of the leak test investigation and will be incorporated into the overall Water Inventory Study Report.

  10. Remote Leak Detection: Indirect Thermal Technique

    NASA Technical Reports Server (NTRS)

    Clements, Sandra

    2002-01-01

    Remote sensing technologies are being considered for efficient, low cost gas leak detection. Eleven specific techniques have been identified for further study and evaluation of several of these is underway. The Indirect Thermal Technique is one of the techniques that is being explored. For this technique, an infrared camera is used to detect the temperature change of a pipe or fitting at the site of a gas leak. This temperature change is caused by the change in temperature of the gas expanding from the leak site. During the 10-week NFFP program, the theory behind the technique was further developed, experiments were performed to determine the conditions for which the technique might be viable, and a proof-of-concept system was developed and tested in the laboratory.

  11. Spontaneous cerebrospinal fluid leak at the clivus

    PubMed Central

    Składzien, Jacek; Betlej, Marek; Chrzan, Robert; Mika, Joanna

    2015-01-01

    We present a case report of a 60-year-old woman with a spontaneous cerebrospinal fluid leak at the clivus, obesity and no history of trauma. Follow-up imaging scans confirmed enlargement of the defect within the posterior clival framework to the size of 16 × 9 × 4 mm with a suspected meningocerebral hernia. The surgeons used the “two nostrils – four hands” endoscopic operating technique. The patient reported a history of cerebrospinal fluid leaks lasting for 3 years, with increasingly shorter leak-free periods and an increasing incidence of inflammatory complications. The patient recovered without complications, and she was discharged 14 days after the surgery. Good local outcome and improved patient condition were achieved postoperatively. PMID:26865899

  12. Leak detection by acoustic emission monitoring. Phase 1. Feasibility study. Final report, August 1987-March 1988

    SciTech Connect

    Lichtenstein, B.; Winder, A.A.

    1994-05-26

    This investigation was conducted to determine the feasibility of detecting leaks from underground storage tanks or pipelines using acoustic emissions. An extensive technical literature review established that distinguishable acoustic emission signals will be generated when a storage tank is subjected to deformation stresses. A parametric analysis was performed which indicated that leak rates less than 0.1 gallons per hour can be detected for leak sizes less than 1/32 inch with 99% probability if the transient signals were sensed with an array of accelerometers (cemented to the tank or via acoustic waveguides), each having a sensitivity greater than 250 mv/g over a frequency range of 0.1 to 4000 Hz, and processed in a multi-channel Fourier spectrum analyzer with automatic threshold detection. An acoustic transient or energy release processor could conceivably detect the onset of the leak at the moment of fracture of the tank wall. The primary limitations to realizing reliable and robust acoustic emission monitoring of underground fluid leaks are the various masking noise sources prevalent at Air Force bases, which are attributed to aircraft, motor traffic, pump station operation, and ground tremors. Acoustic, Leak detection, Underground tank, Pipeline.

  13. Dural Defect Repair in Translabyrinthine Acoustic Neuroma Surgery and Its Implications in Cerebrospinal Fluid Leak Occurrence

    PubMed Central

    Netto, Aloysio Augusto Tahan de Campos; Colafêmina, José Fernando; Centeno, Ricardo Silva

    2012-01-01

    Cerebrospinal fluid (CSF) leak is a complication that may occur after translabyrinthine (translab) acoustic neuroma (AN) removal. The aim of this study is to verify the incidence of CSF leak using two techniques for dural defect closure in translab AN surgery and present a new technique for dural repair. A retrospective study was held, reviewing charts of 34 patients in a tertiary neurotologic referral center. Out of these 34 patients that underwent translab AN excision in a 1-year period, 18 had their dural defect repaired using only abdominal fat graft and 16 using synthetic dura substitute (SDS) plus abdominal fat tissue. One patient (5.5%) in the first group had CSF leak and 1 (6.2%) in the second group had CSF leak postoperatively. Our data suggest that there are no significant differences in CSF leak rates using both techniques, although studies in a larger series must be undertaken to conclude it. We believe that the development of some points in the new technique for dural repair can achieve better results and reduce the CSF leak incidence in the translabyrinthine acoustic neuroma surgery in the near future. PMID:24083124

  14. Standoff gas leak detectors based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Frish, M. B.; Wainner, R. T.; Green, B. D.; Laderer, M. C.; Allen, M. G.

    2005-11-01

    Trace gas sensing and analysis by Tunable Diode Laser Absorption Spectroscopy (TDLAS) has become a robust and reliable technology accepted for industrial process monitoring and control, quality assurance, environmental sensing, plant safety, and infrastructure security. Sensors incorporating well-packaged wavelength-stabilized near-infrared (1.2 to 2.0 μm) laser sources sense over a dozen toxic or industrially-important gases. A large emerging application for TDLAS is standoff sensing of gas leaks, e.g. from natural gas pipelines. The Remote Methane Leak Detector (RMLD), a handheld standoff TDLAS leak survey tool that we developed, is replacing traditional leak detection tools that must be physically immersed within a leak to detect it. Employing a 10 mW 1.6 micron DFB laser, the RMLD illuminates a non-cooperative topographic surface, up to 30 m distant, and analyzes returned scattered light to deduce the presence of excess methane. The eye-safe, battery-powered, 6-pound handheld RMLD enhances walking pipeline survey rates by more than 30%. When combined with a spinning or rastering mirror, the RMLD serves as a platform for mobile leak mapping systems. Also, to enable high-altitude surveying and provide aerial disaster response, we are extending the standoff range to 3000 m by adding an EDFA to the laser transmitter.

  15. Apparatus for Leak Testing Pressurized Hoses

    NASA Technical Reports Server (NTRS)

    Underwood, Steve D. (Inventor); Garrison, Steve G. (Inventor); Gant, Bobby D. (Inventor); Palmer, John R. (Inventor)

    2015-01-01

    A hose-attaching apparatus for leak-testing a pressurized hose may include a hose-attaching member. A bore may extend through the hose-attaching member. An internal annular cavity may extend coaxially around the bore. At least one of a detector probe hole and a detector probe may be connected to the internal annular cavity. At least a portion of the bore may have a diameter which is at least one of substantially equal to and less than a diameter of a hose to be leak-tested.

  16. Technique for detecting liquid metal leaks

    DOEpatents

    Bauerle, James E.

    1979-01-01

    In a system employing flowing liquid metal as a heat transfer medium in contact with tubular members containing a working fluid, i.e., steam, liquid metal leaks through the wall of the tubular member are detected by dislodging the liquid metal compounds forming in the tubular member at the leak locations and subsequently transporting the dislodged compound in the form of an aerosol to a detector responsive to the liquid metal compound. In the application to a sodium cooled tubular member, the detector would consist of a sodium responsive device, such as a sodium ion detector.

  17. Tank 241-A-105 leak assessment

    SciTech Connect

    Not Available

    1991-06-01

    Tank 241-A-105 is one of 149 single shell tanks constructed at Hanford to contain and store highly radioactive wastes originating from the processing of spent nuclear reactor fuel. Radiation detection and temperature monitoring devices installed beneath the tank indicate that several episodes of leakage of waste from the tank have occurred. The aim of this study was to evaluate the previous estimates and reanalyze the data to provide a more accurate estimate of leakage from the tank. The principal conclusions of this study are as follows: Earlier investigators estimated leakage prior to August 1968 at 5,000 to 15,000 gallons. Their estimate appears reasonable. Leakage while the tank was being sluiced (8/68--11/70) probably exceeded 5,000 gallons, but probably did not exceed 30,000 gallons. Insufficient data are available to be more precise. Cooling water added to the tank during the sprinkling phase (11/70 -- 12/78) was approximately 610,000 gallons. Sufficient heat was generated in the tank to evaporate most, and perhaps nearly all, of this water. Radionuclides escaping into the soil under the tank cannot be estimated directly because of many uncertainties. Based on a range of leakage from 10,000 to 45,000 gallons, assumed compositions, and decayed to 1/1/91, radioactivity under the tank is expected to be in the range of 85,000--760,000 curies. Measured radiation peaks were nearly all located directly below the perimeter of the tank and, except in rare cases, they showed no tendency to spread horizontally. Moreover, the maximum radiation readings detected are a very small fraction of the radiation reading in the tank. This is the basis for the conclusion that the rate of leakage and, most likely, the quantity leaked, was small. 51 refs., 5 figs., 3 tabs.

  18. Portable Rapid Test Fuel Tank Leak Detection System

    DTIC Science & Technology

    2010-04-01

    aspects of the bulk tank leak detection method . It is not intended to provide a thorough description of the principles behind the system or how the...no Does the Method detect the presence of water in the bottom of the tank? ( ) yes (X) no B-2 Principle of Operation What technique...rates of 0.10 gal/hr and 0.20 gal/hr with a very high PD and very low PFA. This provides a significant improvement over current methods technologically

  19. Precise Evaluation of Leaked Information with Secure Randomness Extraction in the Presence of Quantum Attacker

    NASA Astrophysics Data System (ADS)

    Hayashi, Masahito

    2015-01-01

    We treat secret key extraction when the eavesdropper has correlated quantum states. We propose quantum privacy amplification theorems different from Renner's, which are based on quantum conditional Rényi entropy of order 1 + s. Using those theorems, we derive an exponential rate of decrease for leaked information and the asymptotic equivocation rate, which have not been derived hitherto in the quantum setting.

  20. COPPER PITTING AND PINHOLE LEAK RESEARCH STUDY

    EPA Science Inventory

    Localized copper corrosion or pitting is a significant problem at many water utilities across the United States. Copper pinhole leak problems resulting from extensive pitting are widely under reported. Given the sensitive nature of the problem, extent of damage possible, costs o...

  1. Microphone Detects Boiler-Tube Leaks

    NASA Technical Reports Server (NTRS)

    Parthasarathy, S. P.

    1985-01-01

    Unit simple, sensitive, rugged, and reliable. Diaphragmless microphone detects leaks from small boiler tubes. Porous plug retains carbon granules in tube while allowing pressure changes to penetrate to granules. Has greater life expectancy than previous controllers and used in variety of hot corrosive atmospheres.

  2. [Ryanodine receptor, calcium leak and arrhythmias].

    PubMed

    Rueda, Angélica; de Alba-Aguayo, David R; Valdivia, Héctor H

    2014-01-01

    The participation of the ionic Ca(2+) release channel/ryanodine receptor in cardiac excitation-contraction coupling is well known since the late '80s, when various seminal papers communicated its purification for the first time and its identity with the "foot" structures located at the terminal cisternae of the sarcoplasmic reticulum. In addition to its main role as the Ca(2+) channel responsible for the transient Ca(2+) increase that activates the contractile machinery of the cardiomyocytes, the ryanodine receptor releases Ca(2+) during the relaxation phase of the cardiac cycle, giving rise to a diastolic Ca(2+) leak. In normal physiological conditions, diastolic Ca(2+) leak regulates the proper level of luminal Ca(2+), but in pathological conditions it participates in the generation of both, acquired and hereditary arrhythmias. Very recently, several groups have focused their efforts into the development of pharmacological tools to control the altered diastolic Ca(2+) leak via ryanodine receptors. In this review, we focus our interest on describing the participation of cardiac ryanodine receptor in the diastolic Ca(2+) leak under physiological or pathological conditions and also on the therapeutic approaches to control its undesired exacerbated activity during diastole.

  3. Locating of leaks in water-cooled generator stator bars using perfluorocarbon tracers

    SciTech Connect

    Loss, W.M.; Dietz, R.N.

    1991-09-01

    Water cooled stator bars in power plant generators often fail during the maintenance cycle due to water leakage. After the hydrogen pressure in the generator shell has been released water can leak through cracks in the copper and through the insulation. Leaking bars, but not the leaks themselves, are detected with so-called hi-pot'' (high potential) tests where direct electrical current is applied to the stator bar windings. A study initiated by ConEd and Brookhaven's Tracer Technology Center to explore the cause of these leakage problems to determine if the failures originate in the manufacturing process or are created in service by phase related torque stresses. To this purpose bars that had failed the hi-pot test were investigated first with the insulation in place and then stripped to the bare copper. The bars were pressurized with gases containing perfluorocarbon tracers and the magnitude and location of the leaks was detected by using tracers technology principles and instruments such as the double source'' method and the Dual Trap Analyzer. In the second part of the project the windings within a generator were tested in-situ for leaks during an outage using tracer principles. Recommendations are given suggesting the shut down of stator bar cooling water before hydrogen bleeding during outages and a revision of the current vent flow rate. The new standard should establish a reasonable leak rate for the stator bar windings proper and exclude leakage of pump seals and connections. Testing during the maintenance cycle in generators should include routine tracer leak detection following the hi-pot test.

  4. Locating of leaks in water-cooled generator stator bars using perfluorocarbon tracers

    SciTech Connect

    Loss, W.M.; Dietz, R.N.

    1991-09-01

    Water cooled stator bars in power plant generators often fail during the maintenance cycle due to water leakage. After the hydrogen pressure in the generator shell has been released water can leak through cracks in the copper and through the insulation. Leaking bars, but not the leaks themselves, are detected with so-called ``hi-pot`` (high potential) tests where direct electrical current is applied to the stator bar windings. A study initiated by ConEd and Brookhaven`s Tracer Technology Center to explore the cause of these leakage problems to determine if the failures originate in the manufacturing process or are created in service by phase related torque stresses. To this purpose bars that had failed the hi-pot test were investigated first with the insulation in place and then stripped to the bare copper. The bars were pressurized with gases containing perfluorocarbon tracers and the magnitude and location of the leaks was detected by using tracers technology principles and instruments such as the ``double source`` method and the Dual Trap Analyzer. In the second part of the project the windings within a generator were tested in-situ for leaks during an outage using tracer principles. Recommendations are given suggesting the shut down of stator bar cooling water before hydrogen bleeding during outages and a revision of the current vent flow rate. The new standard should establish a reasonable leak rate for the stator bar windings proper and exclude leakage of pump seals and connections. Testing during the maintenance cycle in generators should include routine tracer leak detection following the hi-pot test.

  5. The effects of air leaks on solar air heating systems

    NASA Technical Reports Server (NTRS)

    Elkin, R.; Cash, M.

    1979-01-01

    This paper presents the results of an investigation to determine the effects of leakages in collector and duct work on the system performance of a typical single-family residence solar air heating system. Positive (leakage out) and negative (leakage in) pressure systems were examined. Collector and duct leakage rates were varied from 10 to 30 percent of the system flow rate. Within the range of leakage rates investigated, solar contribution to heated space and domestic hot water loads was found to be reduced up to 30 percent from the no-leak system contribution with duct leakage equally divided between supply and return duct; with supply duct leakage greater than return leakage a reduction of up to 35 percent was noted. The negative pressure system exhibited a reduction in solar contribution somewhat larger than the positive pressure system for the same leakage rates.

  6. The leak location package for assessment of the time-frequency correlation method for leak location

    NASA Astrophysics Data System (ADS)

    Faerman, V. A.; Cheremnov, A. G.; Avramchuk, V. S.; Shepetovsky, D. V.

    2017-01-01

    The paper describes the simplest implementation of a software and hardware package for acoustic correlation leak location and results of its performance assessment for location of water leaks from a metallic pipe in laboratory conditions. A distinctive feature of this leak locator is the use of the software based on the time-frequency correlation analysis of signals, which was proposed in our previous papers. Comparative analysis results are given for the information content of classical and time-frequency cross-correlation functions as obtained during processing of experimental data. The results obtained justify comparatively higher efficiency of a time-frequency cross correlation method to solve the leak location task. Improved efficiency is determined by bandpass filtration embedded into the time-frequency cross-correlation function calculation.

  7. Modeling leaks from liquid hydrogen storage systems.

    SciTech Connect

    Winters, William Stanley, Jr.

    2009-01-01

    This report documents a series of models for describing intended and unintended discharges from liquid hydrogen storage systems. Typically these systems store hydrogen in the saturated state at approximately five to ten atmospheres. Some of models discussed here are equilibrium-based models that make use of the NIST thermodynamic models to specify the states of multiphase hydrogen and air-hydrogen mixtures. Two types of discharges are considered: slow leaks where hydrogen enters the ambient at atmospheric pressure and fast leaks where the hydrogen flow is usually choked and expands into the ambient through an underexpanded jet. In order to avoid the complexities of supersonic flow, a single Mach disk model is proposed for fast leaks that are choked. The velocity and state of hydrogen downstream of the Mach disk leads to a more tractable subsonic boundary condition. However, the hydrogen temperature exiting all leaks (fast or slow, from saturated liquid or saturated vapor) is approximately 20.4 K. At these temperatures, any entrained air would likely condense or even freeze leading to an air-hydrogen mixture that cannot be characterized by the REFPROP subroutines. For this reason a plug flow entrainment model is proposed to treat a short zone of initial entrainment and heating. The model predicts the quantity of entrained air required to bring the air-hydrogen mixture to a temperature of approximately 65 K at one atmosphere. At this temperature the mixture can be treated as a mixture of ideal gases and is much more amenable to modeling with Gaussian entrainment models and CFD codes. A Gaussian entrainment model is formulated to predict the trajectory and properties of a cold hydrogen jet leaking into ambient air. The model shows that similarity between two jets depends on the densimetric Froude number, density ratio and initial hydrogen concentration.

  8. REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures

    National Institute of Standards and Technology Data Gateway

    SRD 73 NIST REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures (PC database for purchase)   REFLEAK estimates composition changes of zeotropic mixtures in leak and recharge processes.

  9. 49 CFR 230.64 - Leaks under lagging.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Leaks § 230.64 Leaks under lagging. The steam locomotive owner and/or operator shall take out...

  10. 49 CFR 230.64 - Leaks under lagging.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Leaks § 230.64 Leaks under lagging. The steam locomotive owner and/or operator shall take out...

  11. 49 CFR 230.64 - Leaks under lagging.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Leaks § 230.64 Leaks under lagging. The steam locomotive owner and/or operator shall take out...

  12. 49 CFR 230.64 - Leaks under lagging.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Leaks § 230.64 Leaks under lagging. The steam locomotive owner and/or operator shall take out...

  13. Analysis of Pressure Data As CO2/Brine Leak Diagnostic in Shallow Aquifers

    NASA Astrophysics Data System (ADS)

    Trainor Guitton, W.; Mansoor, K.; Sun, Y.; Carroll, S.

    2014-12-01

    Pressure is a promising signal for detecting CO2leakage from deep, geologic storage reservoirs to shallow groundwater sources. Pressure signals should faster than other physical indications (i.e. electrical or geochemical changes) thus allowing for a timely leak diagnosis and mitigation. We explore the effectiveness of pressure as a detection tool. A simulation-based approach is used to diagnose a CO2/brine leak using pressure data from monitoring wells and to assess the influence of 3 principal uncertainties: distances between the source leak and the monitoring well, heterogeneity of the aquifer flow properties, and CO2 and brine leakage rates. Specifically, five parameters are sampled: the correlation lengths of the vertical and horizontal permeability for the aquifer (2), the sand proportion for each model (1), and the CO2 and brine leakage flux magnitude (2). Areal model dimensions and grid cell dimensions allow for sampling distances of 25 m to 990 m from the leaking well to the monitoring well. We generate 500 simulations by sampling each parameter within an appropriate range predefined by site-specific values. Pressure transducers in monitoring wells will only be accurate at measuring changes on the order of 0.1 to 0.3 PSI. These pressure thresholds are used to establish which simulations are classified as leaks at the leaking location and which locations away from the leak would constitute a signal. We observe 3 conclusions from the results: vertical flow barriers (heterogeneity) creates complicated pressure signals by forcing convoluted flow paths false positives (Pr( No Leak | Signal)) do not occur with our sample simulations false negatives (Pr( Leak | No signal)) dominate after 200 days even when considering only potential monitoring wells within 100m of the leaking well. We use these posteriors to calculate the value of information (VOI) from above zone pressure data. This work was performed under the auspices of the U.S. Department of Energy by

  14. The Prevention and Management of Air Leaks Following Pulmonary Resection.

    PubMed

    Burt, Bryan M; Shrager, Joseph B

    2015-11-01

    Alveolar air leaks are a common problem in the daily practice of thoracic surgeons. Prolonged air leak following pulmonary resection is associated with increased morbidity, increased length of hospital stay, and increased costs. This article reviews the evidence for the various intraoperative and postoperative options to prevent and manage postoperative air leak.

  15. 1999 Leak Detection and Monitoring and Mitigation Strategy Update

    SciTech Connect

    OHL, P.C.

    1999-09-23

    This document is a complete revision of WHC-SD-WM-ES-378, Rev 1. This update includes recent developments in Leak Detection, Leak Monitoring, and Leak Mitigation technologies, as well as, recent developments in single-shell tank retrieval technologies. In addition, a single-shell tank retrieval release protection strategy is presented.

  16. 10 CFR 39.35 - Leak testing of sealed sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Leak testing of sealed sources. 39.35 Section 39.35 Energy....35 Leak testing of sealed sources. (a) Testing and recordkeeping requirements. Each licensee who uses... Commission for 3 years after the leak test is performed. (b) Method of testing. The wipe of a sealed...

  17. 10 CFR 39.35 - Leak testing of sealed sources.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Leak testing of sealed sources. 39.35 Section 39.35 Energy....35 Leak testing of sealed sources. (a) Testing and recordkeeping requirements. Each licensee who uses... Commission for 3 years after the leak test is performed. (b) Method of testing. The wipe of a sealed...

  18. Double Shell Tank AY-102 Radioactive Waste Leak Investigation

    SciTech Connect

    Washenfelder, Dennis J.

    2014-04-10

    PowerPoint. The objectives of this presentation are to: Describe Effort to Determine Whether Tank AY-102 Leaked; Review Probable Causes of the Tank AY-102 Leak; and, Discuss Influence of Leak on Hanford’s Double-Shell Tank Integrity Program.

  19. Effect of heat leaks in platinum resistance thermometry.

    PubMed

    Goldratt, E; Yeshurun, Y; Greenfield, A J

    1980-03-01

    The effect of heat leaks in platinum resistance thermometry is analyzed. An experimental method is proposed for estimating the magnitude of this effect. Results are reported for the measurement of the temperature of a hot, solid body under different heat-leak configurations. Design criteria for thermometers are presented which minimize the effect of such heat leaks.

  20. Effect of heat leaks in platinum resistance thermometry

    NASA Astrophysics Data System (ADS)

    Goldratt, E.; Yeshurun, Y.; Greenfield, A. J.

    1980-03-01

    The effect of heat leaks in platinum resistance thermometry is analyzed. An experimental method is proposed for estimating the magnitude of this effect. Results are reported for the measurement of the temperature of a hot, solid body under different heat-leak configurations. Design criteria for thermometers are presented which minimize the effect of such heat leaks.

  1. 49 CFR 195.134 - CPM leak detection.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false CPM leak detection. 195.134 Section 195.134... PIPELINE Design Requirements § 195.134 CPM leak detection. This section applies to each hazardous liquid... computational pipeline monitoring (CPM) leak detection system and each replaced component of an existing...

  2. 49 CFR 195.134 - CPM leak detection.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false CPM leak detection. 195.134 Section 195.134... PIPELINE Design Requirements § 195.134 CPM leak detection. This section applies to each hazardous liquid... computational pipeline monitoring (CPM) leak detection system and each replaced component of an existing...

  3. 49 CFR 195.444 - CPM leak detection.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false CPM leak detection. 195.444 Section 195.444... PIPELINE Operation and Maintenance § 195.444 CPM leak detection. Each computational pipeline monitoring (CPM) leak detection system installed on a hazardous liquid pipeline transporting liquid in...

  4. 49 CFR 195.444 - CPM leak detection.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false CPM leak detection. 195.444 Section 195.444... PIPELINE Operation and Maintenance § 195.444 CPM leak detection. Each computational pipeline monitoring (CPM) leak detection system installed on a hazardous liquid pipeline transporting liquid in...

  5. Leak Detection and Location Technology Assessment for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Wilson, William C.; Coffey, Neil C.; Madaras, Eric I.

    2008-01-01

    Micro Meteoroid and Orbital Debris (MMOD) and other impacts can cause leaks in the International Space Station and other aerospace vehicles. The early detection and location of leaks is paramount to astronaut safety. Therefore this document surveys the state of the art in leak detection and location technology for aerospace vehicles.

  6. Helium bombardment leak testing of the closure disk weld for MC2949, MC3004, and MC3095 pyrotechnic devices

    SciTech Connect

    Dudley, W.A.

    1980-03-31

    A helium bombardment leak test procedure was developed to determine the leak level of the closure disk weld performed on three nearly identical pyrotechnic actuators. The inspection procedure is capable of leak testing any of the three product types at a rate better than 120 units per 8-hr work shift. Testing is performed on a 100% sample plan and employs a go/no-go bombardment leak rate acceptance specification of 3 x 10/sup -9/ atm-cm/sup 3/-sec/sup -1/. In addition to the current test procedure and results, this report includes a description of procedure and results associated with the test as initially performed. Other applications of the current technique are also listed.

  7. Gels, monomer solutions fix pinhole casing leaks

    SciTech Connect

    Creel, P.; Crook, R.

    1997-10-13

    Sodium silicate gel and in situ polymerizing monomer (IPM) solutions have had nearly 100% success in repairing pinhole casing leaks. These methods are an alternative to small-particle cement squeeze jobs and can be used in both producing and injection wells. The particles in small-particle or fine-grind cement average 5 microns in diameter compared to the 50 micron particles in Portland cement. Repairs not only help satisfy regulatory requirements but also reduce possible related casing repair costs such as during drillouts, repeated cement squeezes, and workovers. If casing leaks in injection wells are unsuccessfully squeezed and fail regulatory testing, the operator may be fined and the wells may have to be plugged and abandoned. The paper describes the repair of both injection and production well casings.

  8. Modeling and measurement of the performance of a branched conduit sampling system in a mass spectrometer leak detector

    NASA Technical Reports Server (NTRS)

    Russell, John M.

    1994-01-01

    In the leak testing of a large engineering system, one may distinguish three stages, namely leakage measurement by an overall enclosure, leak location, and leakage measurement by a local enclosure. Sniffer probes attached to helium mass spectrometer leak detectors are normally designed for leak location, a qualitative inspection technique intended to pinpoint where a leak is but not to quantify its rate of discharge. The main conclusion of the present effort is that local leakage measurement by a leak detector with a sniffer probe is feasible provided one has: (1) quantitative data on the performance of the mass separator cell (a device interior to the unit where the stream of fluid in the sample line branches); and (2) a means of stabilizing the mass transfer boundary layer that is created near a local leak site when a sniffer probe is placed in its immediate vicinity. Theoretical models of the mass separator cell are provided and measurements of the machine-specific parameters in the formulas are presented. A theoretical model of a porous probe end for stabilizing the mass transfer boundary is also presented.

  9. Scintigraphy for Pulmonary Capillary Protein Leak

    DTIC Science & Technology

    1982-09-01

    adrministration (16). The method is noninvasive and has been used clinically to determine the severity and duration of non- cardiogenic pulmonary edema ...If the leak exceeds the 1.iiiphatic capacity, which can increase flow by a factor of 20, pulmcnary interstitial edema occurs. T•hen the interstitial...of shoee is the accepted !::odel for the scudv of pulmonary permehbility - edema (18). It is, therefore, necessary to comnpare our scintigraphic

  10. Scintigraphy for Pulmonary Capillary Protein Leak

    DTIC Science & Technology

    1983-09-01

    det,,rmine the severity and duration of non- cardiogenic pulmonary edema (17). C. Approach to the Problem The anim-als were anesthetize,, intubated and...pulmonary lymphatics. If the leak exceeds the lymphatic capacity, which can increase flow by a factor of 20, pulmonary interstitial edema occurs. When...therefore, does not appear to cause permeability pulmonary edema in either the sheep or dog. The ARDS seen in patients following sclerotherapy of esophageal

  11. Natural gas pipeline leaks across Washington, DC.

    PubMed

    Jackson, Robert B; Down, Adrian; Phillips, Nathan G; Ackley, Robert C; Cook, Charles W; Plata, Desiree L; Zhao, Kaiguang

    2014-01-01

    Pipeline safety in the United States has increased in recent decades, but incidents involving natural gas pipelines still cause an average of 17 fatalities and $133 M in property damage annually. Natural gas leaks are also the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. To reduce pipeline leakage and increase consumer safety, we deployed a Picarro G2301 Cavity Ring-Down Spectrometer in a car, mapping 5893 natural gas leaks (2.5 to 88.6 ppm CH4) across 1500 road miles of Washington, DC. The δ(13)C-isotopic signatures of the methane (-38.2‰ ± 3.9‰ s.d.) and ethane (-36.5 ± 1.1 s.d.) and the CH4:C2H6 ratios (25.5 ± 8.9 s.d.) closely matched the pipeline gas (-39.0‰ and -36.2‰ for methane and ethane; 19.0 for CH4/C2H6). Emissions from four street leaks ranged from 9200 to 38,200 L CH4 day(-1) each, comparable to natural gas used by 1.7 to 7.0 homes, respectively. At 19 tested locations, 12 potentially explosive (Grade 1) methane concentrations of 50,000 to 500,000 ppm were detected in manholes. Financial incentives and targeted programs among companies, public utility commissions, and scientists to reduce leaks and replace old cast-iron pipes will improve consumer safety and air quality, save money, and lower greenhouse gas emissions.

  12. Leak Location and Classification in the Space Shuttle Main Engine Nozzle by Infrared Testing

    NASA Technical Reports Server (NTRS)

    Russell, Samuel S.; Walker, James L.; Lansing, Mathew

    2003-01-01

    The Space Shuttle Main Engine (SSME) is composed of cooling tubes brazed to the inside of a conical structural jacket. Because of the geometry there are regions that can't be inspected for leaks using the bubble solution and low-pressure method. The temperature change due escaping gas is detectable on the surface of the nozzle under the correct conditions. The methods and results presented in this summary address the thermographic identification of leaks in the Space Shuttle Main Engine nozzles. A highly sensitive digital infrared camera is used to record the minute temperature change associated with a leak source, such as a crack or pinhole, hidden within the nozzle wall by observing the inner "hot wall" surface as the nozzle is pressurized. These images are enhanced by digitally subtracting a thermal reference image taken before pressurization, greatly diminishing background noise. The method provides a nonintrusive way of localizing the tube that is leaking and the exact leak source position to within a very small axial distance. Many of the factors that influence the inspectability of the nozzle are addressed; including pressure rate, peak pressure, gas type, ambient temperature and surface preparation.

  13. Leak before break evaluation for main steam piping system made of SA106 Gr.C

    SciTech Connect

    Yang, Kyoung Mo; Jee, Kye Kwang; Pyo, Chang Ryul; Ra, In Sik

    1997-04-01

    The basis of the leak before break (LBB) concept is to demonstrate that piping will leak significantly before a double ended guillotine break (DEGB) occurs. This is demonstrated by quantifying and evaluating the leak process and prescribing safe shutdown of the plant on the basis of the monitored leak rate. The application of LBB for power plant design has reduced plant cost while improving plant integrity. Several evaluations employing LBB analysis on system piping based on DEGB design have been completed. However, the application of LBB on main steam (MS) piping, which is LBB applicable piping, has not been performed due to several uncertainties associated with occurrence of steam hammer and dynamic strain aging (DSA). The objective of this paper is to demonstrate the applicability of the LBB design concept to main steam lines manufactured with SA106 Gr.C carbon steel. Based on the material properties, including fracture toughness and tensile properties obtained from the comprehensive material tests for base and weld metals, a parametric study was performed as described in this paper. The PICEP code was used to determine leak size crack (LSC) and the FLET code was used to perform the stability assessment of MS piping. The effects of material properties obtained from tests were evaluated to determine the LBB applicability for the MS piping. It can be shown from this parametric study that the MS piping has a high possibility of design using LBB analysis.

  14. Integrated Approaches for the Management of Staple Line Leaks following Sleeve Gastrectomy

    PubMed Central

    D'Ugo, Stefano; Di Benedetto, Luca; Gaspari, Achille L.; Gentileschi, Paolo

    2017-01-01

    Introduction. Aim of the study was trying to draw a final flow chart for the management of gastric leaks after laparoscopic sleeve gastrectomy, based on the review of our cases over 10 years' experience. Material and Methods. We retrospectively reviewed all patients who underwent LSG as a primary operation at the Bariatric Unit of Tor Vergata University Hospital in Rome from 2007 to 2015. Results. Patients included in the study were 418. There were 6 staple line leaks (1.44%). All patients with diagnosis of a leak were initially discharged home in good clinical conditions and then returned to A&E because of the complication. The mean interval between surgery and readmission for leak was 13,4 days (range 6–34 days, SD ± 11.85). We recorded one death (16.67%) due to sepsis. The remaining five cases were successfully treated with a mean healing time of the gastric leak of 55,5 days (range 26–83 days; SD ± 25.44). Conclusion. Choosing the proper treatment depends on clinical stability and on the presence or not of collected abscess. Our treatment protocol showed being associated with low complication rate and minor discomfort to the patients, reducing the need for more invasive procedures. PMID:28261497

  15. Propellant Feed System Leak Detection: Lessons Learned From the Linear Aerospike SR-71 Experiment (LASRE)

    NASA Technical Reports Server (NTRS)

    Hass, Neal; Mizukami, Masashi; Neal, Bradford A.; St. John, Clinton; Beil, Robert J.; Griffin, Timothy P.

    1999-01-01

    This paper presents pertinent results and assessment of propellant feed system leak detection as applied to the Linear Aerospike SR-71 Experiment (LASRE) program flown at the NASA Dryden Flight Research Center, Edwards, California. The LASRE was a flight test of an aerospike rocket engine using liquid oxygen and high-pressure gaseous hydrogen as propellants. The flight safety of the crew and the experiment demanded proven technologies and techniques that could detect leaks and assess the integrity of hazardous propellant feed systems. Point source detection and systematic detection were used. Point source detection was adequate for catching gross leakage from components of the propellant feed systems, but insufficient for clearing LASRE to levels of acceptability. Systematic detection, which used high-resolution instrumentation to evaluate the health of the system within a closed volume, provided a better means for assessing leak hazards. Oxygen sensors detected a leak rate of approximately 0.04 cubic inches per second of liquid oxygen. Pressure sensor data revealed speculated cryogenic boiloff through the fittings of the oxygen system, but location of the source(s) was indeterminable. Ultimately, LASRE was cancelled because leak detection techniques were unable to verify that oxygen levels could be maintained below flammability limits.

  16. Remote sensing natural gas leak detector with novel optical filter. Final report, November 1990-August 1993

    SciTech Connect

    Henningsen, T.; Wutzke, S.A.; Garbuny, M.

    1993-12-01

    Each year, more than 100,000 miles of street mains are surveyed for gas leaks with vehicle-mounted gas detection systems. With state of the art (SOA) detection systems, vehicles must travel slowly (2-7 MPH). As a result, the operation in labor-intensive. In initial feasibility studies, a new vehicle-mounted gas leak detection system has demonstrated successful leak detection at vehicle speeds of 20 MPH or more. With these operating conditions, productivity increases of 20-50% or more may be possible. Based on the infrared absorption of methane, the front-mounted detection system performed successfully under a variety of environmental conditions, including rain, and snow, with gas leaks, both simulated and real world. The Concept Evaluation Unit (CEU) was easily able to detect gas concentrations as low as 1 ppm above the universal methane background. In direct performance comparisons with an SOA-equipped vehicle, the CEU performed flawlessly, reporting the presence of gas over a controlled range of gas leak rates and vehicle speeds. Under the same conditions the SOA vehicle incurred both false positives and negatives.

  17. CO2-Leaking Well - Analytical Modeling

    NASA Astrophysics Data System (ADS)

    Wertz, F.; Audigane, P.; Bouc, O.

    2009-04-01

    The long-term integrity of CO2 storage in geological system relies highly on local trapping mechanisms but also on the absence/control of any kind of outlets. Indeed numerous pathways (faults, wells, rock heterogeneities…) exist that can lead stored gas back to the surface. Thus, such leakage risks must be assessed and quantified if possible. In France, BRGM is inquired for evaluating safety criteria and developing a methodology for qualifying potential geological storage sites. This implies in particular to study the leakage scenario, here through a water-filled well as a worth scenario case. In order to determine the kinds of impacts leaking CO2 can have; knowing the velocity and flow rate of uprising CO2 is a necessity. That is why a better knowledge of CO2 in storage conditions and its behaviour with the environment is required. The following study aims at characterising the CO2 flowing into the well and then rising up in a water column over the vertical dimension. An analytical model was built that describes: - In a first step, the CO2 flow between the reservoir and the inside of the well, depending on quality and thickness of different seals, which determines the flow rate through the well. - In a second step, the CO2 uprising through an open and water filled well, however in steady state, which excludes a priori the characterisation of periodic or chaotic behaviours such as geyser formation. The objective is to give numerous orders of magnitude concerning CO2 thermodynamic properties while rising up: specific enthalpy, density, viscosity, velocity, flow, gas volume fraction and expansion, pressure and temperature gradient. Dissolution is partially taken into account, however without kinetic. The strength of this model is to compute analytically - easily and instantaneously - the 1-dimensional rising velocity of CO2 in a water column as a function of the CO2 density, interfacial tension and initial volume fraction. Characteristic speeds - the ones given by

  18. Cryogenic, Absolute, High Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Chapman, John J. (Inventor); Shams. Qamar A. (Inventor); Powers, William T. (Inventor)

    2001-01-01

    A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

  19. 40 CFR 1066.985 - Fuel storage system leak test procedure.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... in = inlet pressure to orifice, in kPa. p atmos = atmospheric pressure, in kPa. SG N2 = specific... reference conditions, based on the measured leak rate corresponding to atmospheric pressure. The corrected... pressure, temperature, and flow to calculate an equivalent orifice diameter for the system. Use...

  20. Emergency membrane contactor based absorption system for ammonia leaks in water treatment plants.

    PubMed

    Shao, Jiahui; Fang, Xuliang; He, Yiliang; Jin, Qiang

    2008-01-01

    Abstract Because of the suspected health risks of trihalomethanes (THMs), more and more water treatment plants have replaced traditional chlorine disinfection process with chloramines but often without the proper absorption system installed in the case of ammonia leaks in the storage room. A pilot plant membrane absorption system was developed and installed in a water treatment plant for this purpose. Experimentally determined contact angle, surface tension, and corrosion tests indicated that the sulfuric acid was the proper choice as the absorbent for leaking ammonia using polypropylene hollow fiber membrane contactor. Effects of several operating conditions on the mass transfer coefficient, ammonia absorption, and removal efficiency were examined, including the liquid concentration, liquid velocity, and feed gas concentration. Under the operation conditions investigated, the gas absorption efficiency over 99.9% was achieved. This indicated that the designed pilot plant membrane absorption system was effective to absorb the leaking ammonia in the model storage room. The removal rate of the ammonia in the model storage room was also experimentally and theoretically found to be primarily determined by the ammonia suction flow rate from the ammonia storage room to the membrane contactor. The ammonia removal rate of 99.9% was expected to be achieved within 1.3 h at the ammonia gas flow rate of 500 m3/h. The success of the pilot plant membrane absorption system developed in this study illustrated the potential of this technology for ammonia leaks in water treatment plant, also paved the way towards a larger scale application.

  1. Absolute Humidity and the Seasonality of Influenza (Invited)

    NASA Astrophysics Data System (ADS)

    Shaman, J. L.; Pitzer, V.; Viboud, C.; Grenfell, B.; Goldstein, E.; Lipsitch, M.

    2010-12-01

    Much of the observed wintertime increase of mortality in temperate regions is attributed to seasonal influenza. A recent re-analysis of laboratory experiments indicates that absolute humidity strongly modulates the airborne survival and transmission of the influenza virus. Here we show that the onset of increased wintertime influenza-related mortality in the United States is associated with anomalously low absolute humidity levels during the prior weeks. We then use an epidemiological model, in which observed absolute humidity conditions temper influenza transmission rates, to successfully simulate the seasonal cycle of observed influenza-related mortality. The model results indicate that direct modulation of influenza transmissibility by absolute humidity alone is sufficient to produce this observed seasonality. These findings provide epidemiological support for the hypothesis that absolute humidity drives seasonal variations of influenza transmission in temperate regions. In addition, we show that variations of the basic and effective reproductive numbers for influenza, caused by seasonal changes in absolute humidity, are consistent with the general timing of pandemic influenza outbreaks observed for 2009 A/H1N1 in temperate regions. Indeed, absolute humidity conditions correctly identify the region of the United States vulnerable to a third, wintertime wave of pandemic influenza. These findings suggest that the timing of pandemic influenza outbreaks is controlled by a combination of absolute humidity conditions, levels of susceptibility and changes in population mixing and contact rates.

  2. Low leak rate poppet-and-seat check valve

    NASA Technical Reports Server (NTRS)

    Whitten, D. E.

    1970-01-01

    Valve leakage due to contaminant entrapment and chattering is effectively minimized by a metallic poppet-and-seat check valve designed for use in extreme environmental and fluid temperature conditions.

  3. Use of IHTS pipe leak jacketing for LSPB

    SciTech Connect

    1983-08-15

    In an effort to reduce costs of the Large Scale Prototype Breeder (LSPB), Westinghouse and Burns and Roe examined the use of leak jacketing the Intermediate Heat Transport System (IHTS) piping in the Steam Generation Building (SGB) to reduce the amount of sodium leaked to the SGB atmosphere. The design basis leak for the LSPB, IHTS, is an Moderate Energy Fluid System (MEFS) leak. Previous calculations performed for the Mainstream Design SGB showed that high pressures, temperature and hydrogen concentrations would be produced as a result of the sodium leak. The high pressures would mean that the SGB would have to be vented to avoid overpressurization. Venting the SGB results in the dispersion of large quantities of sodium aerosols which can be ingested into reactor or spent fuel decay heat removal heat exchangers, the control room HVAC or the emergency gas turbines. This would require expensive design changes or relocating plant safety related equipment. By leak jacketing the IHTS piping, the effects of the sodium leak in the SGB can be greatly reduced. As a result of this study, it is recommended that leak jacketing of the large diameter IHTS piping in the SGB be used in the design of LSPB. The leak jacketing concept was the most cost effective means of mitigating the consequences of an MEFS leak in the SGB. This report shows the basis and results of the anaylsis, mitigation features and costs, and conclusions.

  4. Hierarchical leak detection and localization method in natural gas pipeline monitoring sensor networks.

    PubMed

    Wan, Jiangwen; Yu, Yang; Wu, Yinfeng; Feng, Renjian; Yu, Ning

    2012-01-01

    In light of the problems of low recognition efficiency, high false rates and poor localization accuracy in traditional pipeline security detection technology, this paper proposes a type of hierarchical leak detection and localization method for use in natural gas pipeline monitoring sensor networks. In the signal preprocessing phase, original monitoring signals are dealt with by wavelet transform technology to extract the single mode signals as well as characteristic parameters. In the initial recognition phase, a multi-classifier model based on SVM is constructed and characteristic parameters are sent as input vectors to the multi-classifier for initial recognition. In the final decision phase, an improved evidence combination rule is designed to integrate initial recognition results for final decisions. Furthermore, a weighted average localization algorithm based on time difference of arrival is introduced for determining the leak point's position. Experimental results illustrate that this hierarchical pipeline leak detection and localization method could effectively improve the accuracy of the leak point localization and reduce the undetected rate as well as false alarm rate.

  5. Hierarchical Leak Detection and Localization Method in Natural Gas Pipeline Monitoring Sensor Networks

    PubMed Central

    Wan, Jiangwen; Yu, Yang; Wu, Yinfeng; Feng, Renjian; Yu, Ning

    2012-01-01

    In light of the problems of low recognition efficiency, high false rates and poor localization accuracy in traditional pipeline security detection technology, this paper proposes a type of hierarchical leak detection and localization method for use in natural gas pipeline monitoring sensor networks. In the signal preprocessing phase, original monitoring signals are dealt with by wavelet transform technology to extract the single mode signals as well as characteristic parameters. In the initial recognition phase, a multi-classifier model based on SVM is constructed and characteristic parameters are sent as input vectors to the multi-classifier for initial recognition. In the final decision phase, an improved evidence combination rule is designed to integrate initial recognition results for final decisions. Furthermore, a weighted average localization algorithm based on time difference of arrival is introduced for determining the leak point’s position. Experimental results illustrate that this hierarchical pipeline leak detection and localization method could effectively improve the accuracy of the leak point localization and reduce the undetected rate as well as false alarm rate. PMID:22368464

  6. Correlation of leak rates of various fluids with the leak rate of an inert gas in the same configuration

    NASA Technical Reports Server (NTRS)

    Schleier, Howard

    1990-01-01

    NASA is interested in field testing for possible leakage in their fueling systems; however, many fuels are hazardous to the extent that personnel cannot be on hand when the system is being monitored. It is proposed that an inert material such as helium be used on the field test, and that those results be calibrated to simulate the actual process. A technique such as this would allow personnel to be on site during the testing and use techniques to determine the behavior of the system that could not be used otherwise. This endeavor attempts to develop such a correlation. The results show promise, but more refinement and data are needed.

  7. One-Piece Leak-Proof Battery

    DOEpatents

    Verhoog, Roelof

    1999-03-23

    The casing of a leak-proof one-piece battery is made of a material comprising a mixture of at least a matrix based on polypropylene and an alloy of a polyamide and a polypropylene. The ratio of the matrix to the alloy is in the range 0.5 to 6 by weight. The alloy forms elongate arborescent inclusions in the matrix such that, on average, the largest dimension of a segment of the arborescence is at least twenty times the smallest dimension of the segment.

  8. Low heat-leak cryogenic envelope

    DOEpatents

    DeHaan, James R.

    1976-10-19

    A plurality of cryogenic envelope sections are joined together to form a power transmission line. Each of the sections is comprised of inner and outer tubes having multilayer metalized plastic spirally wrapped within a vacuum chamber formed between the inner and outer tubes. A refrigeration tube traverses the vacuum chamber, but exits one section and enters another through thermal standoffs for reducing heat-leak from the outer tube to the refrigeration tube. The refrigeration tube passes through a spirally wrapped shield within each section's vacuum chamber in a manner so that the refrigeration tube is in close thermal contact with the shield, but is nevertheless slideable with respect thereto.

  9. Database applicaton for absolute spectrophotometry

    NASA Astrophysics Data System (ADS)

    Bochkov, Valery V.; Shumko, Sergiy

    2002-12-01

    32-bit database application with multidocument interface for Windows has been developed to calculate absolute energy distributions of observed spectra. The original database contains wavelength calibrated observed spectra which had been already passed through apparatus reductions such as flatfielding, background and apparatus noise subtracting. Absolute energy distributions of observed spectra are defined in unique scale by means of registering them simultaneously with artificial intensity standard. Observations of sequence of spectrophotometric standards are used to define absolute energy of the artificial standard. Observations of spectrophotometric standards are used to define optical extinction in selected moments. FFT algorithm implemented in the application allows performing convolution (deconvolution) spectra with user-defined PSF. The object-oriented interface has been created using facilities of C++ libraries. Client/server model with Windows Socket functionality based on TCP/IP protocol is used to develop the application. It supports Dynamic Data Exchange conversation in server mode and uses Microsoft Exchange communication facilities.

  10. Steam-leak cost estimation using thermographically acquired pipe temperature data

    NASA Astrophysics Data System (ADS)

    Madding, Robert P.; MacNamara, Neal A.

    1997-04-01

    Predictive maintenance practitioners readily diagnose steam leaks through drain using infrared thermography, often supplemented with ultrasonic probe verification. Typically, a pipe carries the leaking steam to a flash tank or directly to the condenser. Thus, the energy used to create the steam is what is lost, not the steam itself. However, the cost of steam production is not inexpensive. We have found steam leaks we estimate cost $30 K/year. As a part of the Electric Power Research Institute's (EPRI's) Boiler, Condenser and Steam Cycle Applications Project, the EPRI M&D (Monitoring & Diagnostic) Centers have begun acquiring steam leak data at several electric utilities. Estimates of steam leak costs are key to evaluating cost savings and recommendation of corrective action, but are hampered by lack of knowledge of the steam flow in the line. These lines are usually not instrumented because typically there is no flow. Consequently, we must derive an indirect method of estimating steam flow. This can be done for uninsulated pipes given knowledge of the pipe surface temperature gradient over a known distance. For single phase conditions, the mass flow of steam equals the heat lost from a length of pipe divided by the temperature drop along the length and the heat capacity of the steam. Pipe heat loss is calculated knowing the pipe diameter, pipe surface temperature, ambient air temperature and using American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) tabulated values. The temperatures are derived from thermographic data. Distances can also be derived from thermal imaging radiometer data, depending on the type of system employed. To facilitate calculation of steam leak cost estimates, we have developed a Microsoft ExcelTM spreadsheet macro. The user can interface directly with the spreadsheet, entering appropriate temperatures, distances, pipe diameter, heat rate, cost of power, etc. Or, the analyst can use thermal imaging radiometer

  11. A Hydrogen Leak Detection System for Aerospace and Commercial Applications

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Makel, D. B.; Jansa, E. D.; Patterson, G.; Cova, P. J.; Liu, C. C.; Wu, Q. H.; Powers, W. T.

    1995-01-01

    Leaks on the space shuttle while on the launch pad have generated interest in hydrogen leak monitoring technology. Microfabricated hydrogen sensors are being fabricated at Case Western Reserve University (CWRU) and tested at NASA Lewis Research Center (LeRC). These sensors have been integrated into hardware and software designed by Aerojet. This complete system allows for multipoint leak monitoring designed to provide leak source and magnitude information in real time. The monitoring system processes data from the hydrogen sensors and presents the operator with a visual indication of the leak location and magnitude. Although the leak monitoring system was designed for hydrogen propulsion systems, the possible applications of this monitoring system are wide ranged. This system is in operation in an automotive application which requires high sensitivity to hydrogen.

  12. A hydrogen leak detection system for aerospace and commercial applications

    NASA Astrophysics Data System (ADS)

    Hunter, Gary W.; Makel, D. B.; Jansa, E. D.; Patterson, G.; Cova, P. J.; Liu, C. C.; Wu, Q. H.; Powers, W. T.

    1995-10-01

    Leaks on the space shuttle while on the launch pad have generated interest in hydrogen leak monitoring technology. Microfabricated hydrogen sensors are being fabricated at Case Western Reserve University (CWRU) and tested at NASA Lewis Research Center (LeRC). These sensors have been integrated into hardware and software designed by Aerojet. This complete system allows for multipoint leak monitoring designed to provide leak source and magnitude information in real time. The monitoring system processes data from the hydrogen sensors and presents the operator with a visual indication of the leak location and magnitude. Although the leak monitoring system was designed for hydrogen propulsion systems, the possible applications of this monitoring system are wide ranged. This system is in operation in an automotive application which requires high sensitivity to hydrogen.

  13. [Leak test for the internal circuit of anesthesia machines].

    PubMed

    Tokumine, J; Iha, H; Okuda, Y

    1999-05-01

    In spite of detailed periodic inspection performed by specialized engineers, a great number of anesthesia machines fail to meet the standard of low flow leak test because of leak in the internal circuit. To find out the background and the solution to the problem, we sent questionnaire to 11 major manufacturers and/or dealers each responsible for periodic inspection of anesthetic machines. According to the responses to the questionnaire, the manufacturers and/or the dealers had various methods of internal circuit leak test without a unified standard in detail. The mismatch of the test methods with those anesthesia machines equipped with check valve mechanism has also led to poor evaluation of internal circuit leak. Leak test must be standardized for its appropriate application to work effectively for the problem of leak in the internal circuit of anesthesia machines.

  14. Absolute classification with unsupervised clustering

    NASA Technical Reports Server (NTRS)

    Jeon, Byeungwoo; Landgrebe, D. A.

    1992-01-01

    An absolute classification algorithm is proposed in which the class definition through training samples or otherwise is required only for a particular class of interest. The absolute classification is considered as a problem of unsupervised clustering when one cluster is known initially. The definitions and statistics of the other classes are automatically developed through the weighted unsupervised clustering procedure, which is developed to keep the cluster corresponding to the class of interest from losing its identity as the class of interest. Once all the classes are developed, a conventional relative classifier such as the maximum-likelihood classifier is used in the classification.

  15. EPA Chases Leaks in New Mexico during Seventh Annual Fix a Leak Week

    EPA Pesticide Factsheets

    DALLAS - (March 16, 2015) Dripping faucets and leaky toilets account for a large portion of home water waste. Every year, more than 10,000 gallons of water is wasted in homes due to easy-to-fix leaks. The U.S. Environmental Protection Agency (EPA) i

  16. Leak locating microphone, method and system for locating fluid leaks in pipes

    DOEpatents

    Kupperman, David S.; Spevak, Lev

    1994-01-01

    A leak detecting microphone inserted directly into fluid within a pipe includes a housing having a first end being inserted within the pipe and a second opposed end extending outside the pipe. A diaphragm is mounted within the first housing end and an acoustic transducer is coupled to the diaphragm for converting acoustical signals to electrical signals. A plurality of apertures are provided in the housing first end, the apertures located both above and below the diaphragm, whereby to equalize fluid pressure on either side of the diaphragm. A leak locating system and method are provided for locating fluid leaks within a pipe. A first microphone is installed within fluid in the pipe at a first selected location and sound is detected at the first location. A second microphone is installed within fluid in the pipe at a second selected location and sound is detected at the second location. A cross-correlation is identified between the detected sound at the first and second locations for identifying a leak location.

  17. The regulation and physiology of mitochondrial proton leak.

    PubMed

    Divakaruni, Ajit S; Brand, Martin D

    2011-06-01

    Mitochondria couple respiration to ATP synthesis through an electrochemical proton gradient. Proton leak across the inner membrane allows adjustment of the coupling efficiency. The aim of this review is threefold: 1) introduce the unfamiliar reader to proton leak and its physiological significance, 2) review the role and regulation of uncoupling proteins, and 3) outline the prospects of proton leak as an avenue to treat obesity, diabetes, and age-related disease.

  18. Narrative Review: Clarkson Disease-Systemic Capillary Leak Syndrome

    PubMed Central

    Druey, Kirk M.; Greipp, Philip R.

    2010-01-01

    In 1960, Dr. Bayard Clarkson described a patient experiencing sporadic episodes of hypovolemia, hypotension, and edema. Plasma during the acute attack induced a “shock”-like syndrome when given systemically in rats. The unusual and enigmatic “Systemic Capillary Leak Syndrome” (SCLS) named for Dr. Clarkson is of unknown etiology and is characterized by transient, severe, reversible hemoconcentration and hypoalbuminemia due to leakage of fluids and macromolecules (up to 900 kDa) into tissues (1). Fewer than 150 cases of SCLS have been reported since 1960, but the nonspecific presenting symptoms and signs and high mortality rate may have resulted in under-recognition of this disorder. Given the substantial overlap of SCLS with other “shock” syndromes, including sepsis, anaphylaxis, and angioedema, clinicians should consider this diagnosis in patients with unexplained edema, increased hematocrit, and hypotension. PMID:20643990

  19. SIXTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

    SciTech Connect

    Daugherty, W.

    2011-08-31

    (CSR) data. These two predictive models show reasonable agreement at higher temperatures (350-400 F). However, at 300 F, the room temperature leak test failures to date experienced longer aging times than predicted by the CSR-based model. This suggests that extrapolations of the CSR model predictions to temperatures below 300 F will provide a conservative prediction of service life relative to the leak rate criterion. Leak test failure data at lower temperatures are needed to verify this apparent trend. Insufficient failure data exist currently to perform a similar comparison for GLT-S O-rings. Aging and periodic leak testing will continue for the remaining fixtures.

  20. Leak Mitigation in Mechanically Pumped Fluid Loops for Long Duration Space Missions

    NASA Technical Reports Server (NTRS)

    Miller, Jennifer R.; Birur, Gajanana; Bame, David; Mastropietro, A. J.; Bhandari, Pradeep; Lee, Darlene; Karlmann, Paul; Liu, Yuanming

    2013-01-01

    Mechanically pumped fluid loops (MPFLs) are increasingly considered for spacecraft thermal control. A concern for long duration space missions is the leak of fluid leading to performance degradation or potential loop failure. An understanding of leak rate through analysis, as well as destructive and non-destructive testing, provides a verifiable means to quantify leak rates. The system can be appropriately designed to maintain safe operating pressures and temperatures throughout the mission. Two MPFLs on the Mars Science Laboratory Spacecraft, launched November 26, 2011, maintain the temperature of sensitive electronics and science instruments within a -40 deg C to 50 deg C range during launch, cruise, and Mars surface operations. With over 100 meters of complex tubing, fittings, joints, flex lines, and pumps, the system must maintain a minimum pressure through all phases of the mission to provide appropriate performance. This paper describes the process of design, qualification, test, verification, and validation of the components and assemblies employed to minimize risks associated with excessive fluid leaks from pumped fluid loop systems.

  1. Lymphangiography in the Diagnosis and Localization of Various Chyle Leaks

    SciTech Connect

    Deso, Steve; Ludwig, Benjamin; Kabutey, Nii-Kabu; Kim, Ducksoo; Guermazi, Ali

    2012-02-15

    Purpose: Chyle leaks are rare entities infrequently encountered by most physicians. However, large centers providing advanced surgical care are inevitably confronted with chyle leaks as a complication of surgery, an extension of disease, or as a primary disorder. Regardless of the etiology, proper diagnosis and localization are paramount in the management of any chyle leak. Materials and Methods: Here we present 16 patients with 17 chyle leaks (5 chyluria, 8 chylothorax, and 4 chylous ascites) who underwent bipedal lymphangiography (LAG) and postprocedure computed tomography (CT) imaging. Results: In each case, the source of the chyle leak was identified and properly localized to guide further treatment. Of the 16 patients who underwent LAG and postprocedure CT imaging, the initial LAG alone provided the diagnosis and localized the chyle leak in 4 patients (25%); the postprocedure CT imaging provided the diagnosis and localized the chyle leak in 6 patients (37.5%); and the two modalities were equal in the diagnosing and localizing the chyle leak in the remaining 6 patients (37.5%)ConclusionThese cases highlight the unparalleled abilities of LAG and the added benefit of post-LAG CT imaging in the diagnosis and fine anatomic localization of chyle leaks. In addition, these cases demonstrate the retained utility of LAG in these investigations despite the development of alternative tests involving CT, magnetic resonance imaging, and nuclear medicine imaging.

  2. Method to control the amount of helium during leak testing

    SciTech Connect

    Frank E. Jurvic, Jr.

    2002-03-29

    The purpose of this paper is to demonstrate a method for limiting the amount of helium administered during leak testing and provide a method for keeping the atmospheric helium in a location to a minimum to eliminate backstreaming into the system. This method utilizes the permeability of a balloon. The transporting of helium to the leak check area is also safer by not requiring a cylinder in the leak check location. Utilizing the many shapes of balloons and partially filling of the balloon, any configuration can deliver helium to the leak location. The balloon I filled for the test fell to the floor with the amount of helium I put into the balloon.

  3. Absolute transition probabilities of phosphorus.

    NASA Technical Reports Server (NTRS)

    Miller, M. H.; Roig, R. A.; Bengtson, R. D.

    1971-01-01

    Use of a gas-driven shock tube to measure the absolute strengths of 21 P I lines and 126 P II lines (from 3300 to 6900 A). Accuracy for prominent, isolated neutral and ionic lines is estimated to be 28 to 40% and 18 to 30%, respectively. The data and the corresponding theoretical predictions are examined for conformity with the sum rules.-

  4. Relativistic Absolutism in Moral Education.

    ERIC Educational Resources Information Center

    Vogt, W. Paul

    1982-01-01

    Discusses Emile Durkheim's "Moral Education: A Study in the Theory and Application of the Sociology of Education," which holds that morally healthy societies may vary in culture and organization but must possess absolute rules of moral behavior. Compares this moral theory with current theory and practice of American educators. (MJL)

  5. Absolute Standards for Climate Measurements

    NASA Astrophysics Data System (ADS)

    Leckey, J.

    2016-10-01

    In a world of changing climate, political uncertainty, and ever-changing budgets, the benefit of measurements traceable to SI standards increases by the day. To truly resolve climate change trends on a decadal time scale, on-orbit measurements need to be referenced to something that is both absolute and unchanging. One such mission is the Climate Absolute Radiance and Refractivity Observatory (CLARREO) that will measure a variety of climate variables with an unprecedented accuracy to definitively quantify climate change. In the CLARREO mission, we will utilize phase change cells in which a material is melted to calibrate the temperature of a blackbody that can then be observed by a spectrometer. A material's melting point is an unchanging physical constant that, through a series of transfers, can ultimately calibrate a spectrometer on an absolute scale. CLARREO consists of two primary instruments: an infrared (IR) spectrometer and a reflected solar (RS) spectrometer. The mission will contain orbiting radiometers with sufficient accuracy to calibrate other space-based instrumentation and thus transferring the absolute traceability. The status of various mission options will be presented.

  6. CALM: cascading system with leaking detection mechanism for medical image segmentation

    NASA Astrophysics Data System (ADS)

    Liu, Jiang; Lim, Joo Hwee; Li, Huiqi

    2008-03-01

    Medical image segmentation is a challenging process due to possible image over-segmentation and under-segmentation (leaking). The CALM medical image segmentation system is constructed with an innovative scheme that cascades threshold level-set and region-growing segmentation algorithms using Union and Intersection set operators. These set operators help to balance the over-segmentation rate and under-segmentation rate of the system respectively. While adjusting the curvature scalar parameter in the threshold level-set algorithm, we observe that the abrupt change in the size of the segmented areas coincides with the occurrences of possible leaking. Instead of randomly choose a value or use the system default curvature scalar values, this observation prompts us to use the following formula in CALM to automatically decide the optimal curvature values γ to prevent the occurrence of leaking : δ2S/δγ2 >= M, where S is the size of the segmented area and M is a large positive number. Motivated for potential applications in organ transplant and analysis, the CALM system is tested on the segmentation of the kidney regions from the Magnetic Resonance images taken from the National University Hospital of Singapore. Due to the nature of MR imaging, low-contrast, weak edges and overlapping regions of adjacent organs at kidney boundaries are frequently seen in the datasets and hence kidney segmentation is prone to leaking. The kidney segmentation accuracy rate achieved by CALM is 22% better compared with those achieved by the component algorithms or the system without leaking detection mechanism. CALM is easy-to-implement and can be applied to many applications besides kidney segmentation.

  7. Quantifying Urban Natural Gas Leaks from Street-level Methane Mapping: Measurements and Uncertainty

    NASA Astrophysics Data System (ADS)

    von Fischer, J. C.; Ham, J. M.; Griebenow, C.; Schumacher, R. S.; Salo, J.

    2013-12-01

    Leaks from the natural gas pipeline system are a significant source of anthropogenic methane in urban settings. Detecting and repairing these leaks will reduce the energy and carbon footprints of our cities. Gas leaks can be detected from spikes in street-level methane concentrations measured by analyzers deployed on vehicles. While a spike in methane concentration indicates a leak, an algorithm (e.g., inverse model) must be used to estimate the size of the leak (i.e., flux) from concentration data and supporting meteorological information. Unfortunately, this drive-by approach to leak quantification is confounded by the complexity of urban roughness, changing weather conditions, and other incidental factors (e.g., traffic, vehicle speed, etc.). Furthermore, the vehicle might only pass through the plume one to three times during routine mapping. The objective of this study was to conduct controlled release experiments to better quantify the relationship between mobile methane concentration measurements and the size and location of the emission source (e.g., pipeline leakage) in an urban environment. A portable system was developed that could release methane at known rates between 10 and 40 LPM while maintaining concentrations below the lower explosive limit. A mapping vehicle was configured with fast response methane analyzers, GPS, and meteorological instruments. Portable air-sampling tripods were fabricated that could be deployed at defined distances downwind from the release point and automatically-triggered to collect grab samples. The experimental protocol was as follows: (1) identify an appropriate release point within a city, (2) release methane at a known rate, (3) measure downwind street-level concentrations with the vehicle by making multiple passes through the plume, and (4) collect supporting concentration and meteorological data with the static tripod samplers deployed in the plume. Controlled release studies were performed at multiple locations and

  8. Steel Casing Resistivity Technology (SCRT): Innovative Applications of Electrical Methods for Buried Tank Leak Detection

    NASA Astrophysics Data System (ADS)

    Fink, J. B.; Levitt, M. T.; Gee, G. W.

    2002-12-01

    The need for non-invasive leak detection methods is extremely important for monitoring cleanup efforts of nuclear waste contained in underground storage tanks at the Hanford Nuclear Facility in Washington. Drilling is both very expensive and undesirable in the tank farms. Various geophysical imaging methods were evaluated over the past two years at two "cold" sites but within geologic conditions similar to the tank farms. The "cold" sites consisted of 1. a dense array of 32 steel casings, and 2. a "mock tank" in which various controlled leaks (injections) of a saturated aqueous solution of Na2S2O35H20 were metered. Nearly all methods required invasive drilling for subsurface placement of sensors. An innovative direct-current electrical method using existing infrastructure as grounding electrodes, such as steel casings and steel tanks, has shown very promising results and is undergoing further testing. The most useful results have been obtained by using multiple grounding points for spatial determinations and continuous time-series monitoring for temporal variations. Although the large size of tanks and lengths of casings make discrete volume estimations difficult, data acquired for test leaks to date have shown a surprising correlation between leak rates and the rate-of-change of specific electrical measurements. First order volume approximations can be made based on existing knowledge of the geologic environment and hydraulic parameters. Spatial data provide general leak location and gross flow characteristics, whereas temporal data indicate test leak commencement, cessation, and approximate leak rates. On-going testing is providing quantitative calibration information that is expected to transfer to the tank farm environments. Procedures are being developed that will simplify the installation and operation of the system in the tank-farm environments. Implementation of the technology necessitated remote operation and monitoring of the electrical system

  9. Comprehensive leak detection survey and benefit/cost analysis

    SciTech Connect

    Scholze, R.J. Jr.; Maloney, S.W.

    1995-06-01

    Fort Carson, Colorado was the site of a comprehensive leak detection investigation of the potable water system with the express purpose of quantifying the benefits to be derived by a military installation from use of leak detection and repair technology. Military bases are often the size of a small city and one Directorate or Department has responsibility for all real estate (buildings, roads, grounds, etc.) unlike a municipal public works department. The investigation used state of the art noise correlation and computer correlation technology to survey the distribution system mains. This was complemented by a building to building survey covering office and commercial buildings along with family and barracks housing where investigators entered buildings and quantified visible leaks in faucets and water closets, etc. Following repairs and a year`s time, a follow-on survey is performed to again examine all aspects of the system. The result was a complete economic evaluation and benefit/cost analysis of the installation. Representative findings include: the majority of distribution system leaks were at hydrants or similar appurtenances; and family housing was found to be the other major concentration of leaks. However, where the first survey found 80 percent of housing units had leaks, findings from the second round on the order of 20 percent. Office buildings were found from the first survey to not merit follow-on attention due to limited numbers of leaks. Water-consciousness was raised for both the responsible directorate and individuals in family housing and leak repair was given a higher priority for repairs. This paper will outline the leak detection methodology used, characterize the types and patterns of leaks found, introduce an economic analysis for the entire leak detection process, and finally, provide lessons learned with practical results and implications.

  10. Large-area imager of hydrogen leaks in fuel cells using laser-induced breakdown spectroscopy.

    PubMed

    Hori, M; Hayano, R S; Fukuta, M; Koyama, T; Nobusue, H; Tanaka, J

    2009-10-01

    We constructed a simple device, which utilized laser-induced breakdown spectroscopy to image H2 gas leaking from the surfaces of hydrogen fuel cells to ambient air. Nanosecond laser pulses of wavelength lambda=532 nm emitted from a neodymium-doped yttrium aluminum garnet laser were first compressed to a pulse length Deltat<1 ns using a stimulated Brillouin backscattering cell. Relay-imaging optics then focused this beam onto the H(2) leak and initiated the breakdown plasma. The Balmer-alpha (H-alpha) emission that emerged from this was collected with a 2-m-long macrolens assembly with a 90-mm-diameter image area, which covered a solid angle of approximately 1 x 10(-3)pi steradians seen from the plasma. The H-alpha light was isolated by two 100-mm-diameter interference filters with a 2 nm bandpass, and imaged by a thermoelectrically cooled charge-coupled device camera. By scanning the position of the laser focus, the spatial distribution of H2 gas over a 90-mm-diameter area was photographed with a spatial resolution of < or = 5 mm. Photoionization of the water vapor in the air caused a strong H-alpha background. By using pure N2 as a buffer gas, H2 leaks with rates of <1 cc/min were imaged. We also studied the possibilities of detecting He, Ne, or Xe gas leaks.

  11. Geomechanical analysis to predict the oil leak at the wellbores in Big Hill Strategic Petroleum Reserve

    SciTech Connect

    Park, Byoung Yoon

    2014-02-01

    Oil leaks were found in wellbores of Caverns 105 and 109 at the Big Hill Strategic Petroleum Reserve site. According to the field observations, two instances of casing damage occurred at the depth of the interbed between the caprock bottom and salt top. A three dimensional finite element model, which contains wellbore element blocks and allows each cavern to be configured individually, is constructed to investigate the wellbore damage mechanism. The model also contains element blocks to represent interface between each lithology and a shear zone to examine the interbed behavior in a realistic manner. The causes of the damaged casing segments are a result of vertical and horizontal movements of the interbed between the caprock and salt dome. The salt top subsides because the volume of caverns below the salt top decrease with time due to salt creep closure, while the caprock subsides at a slower rate because the caprock is thick and stiffer. This discrepancy yields a deformation of the well. The deformed wellbore may fail at some time. An oil leak occurs when the wellbore fails. A possible oil leak date of each well is determined using the equivalent plastic strain failure criterion. A well grading system for a remediation plan is developed based on the predicted leak dates of each wellbore.

  12. FIFTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

    SciTech Connect

    Daugherty, W.; Hoffman, E.

    2011-04-11

    A series of experiments to monitor the aging performance of Viton{reg_sign} GLT O-rings used in the Model 9975 package has been ongoing for six years at the Savannah River National Laboratory. Sixty-seven mock-ups of 9975 Primary Containment Vessels (PCVs) were assembled and heated to temperatures ranging from 200 to 450 F. They were leak-tested initially and have been tested at nominal six month intervals to determine if they meet the criterion of leaktightness defined in ANSI standard N14.5-97. Fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 F. High temperature aging continues for 36 GLT O-ring fixtures at 200-350 F. Room temperature leak test failures have been experienced in 6 of the GLT O-ring fixtures aging at 300 and 350 F, and in all 3 of the GLT O-ring fixtures aging at higher temperatures. No failures have yet been observed in GLT O-ring fixtures aging at 200 F for 30-48 months, which is still bounding to O-ring temperatures during storage in KAMS. High temperature aging continues for 6 GLT-S O-ring fixtures at 200-300 F. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 F. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 or 300 F for 19 months. For O-ring fixtures that have failed the room temperature leak test and been disassembled, the Orings displayed a compression set ranging from 51-95%. This is significantly greater than seen to date for packages inspected during KAMS field surveillance (23% average). For GLT O-rings, service life based on the room temperature leak rate criterion is comparable to that predicted by compression stress relaxation (CSR) data at higher temperatures (350-400 F). While there are no comparable failure data yet at aging temperatures below 300 F, extrapolations of the data for GLT O-rings suggests the CSR model predictions provide a conservative prediction of service

  13. FIFTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

    SciTech Connect

    Daugherty, W.; Hoffman, E.

    2010-11-01

    A series of experiments to monitor the aging performance of Viton{sup reg.} GLT O-rings used in the Model 9975 package has been ongoing for six years at the Savannah River National Laboratory. Sixty-seven mock-ups of 9975 Primary Containment Vessels (PCVs) were assembled and heated to temperatures ranging from 200 to 450 F. They were leak-tested initially and have been tested at nominal six month intervals to determine if they meet the criterion of leaktightness defined in ANSI standard N14.5-97. Fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 F. High temperature aging continues for 36 GLT O-ring fixtures at 200--350 F. Room temperature leak test failures have been experienced in 5 of the GLT O-ring fixtures aging at 300 and 350 F, and in all 3 of the GLT O-ring fixtures aging at higher temperatures. No failures have yet been observed in GLT O-ring fixtures aging at 200 F for 30--48 months, which is still bounding to O-ring temperatures during storage in KAMS. High temperature aging continues for 6 GLT-S O-ring fixtures at 200--300 F. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 F. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 or 300 F for 19 months. For O-ring fixtures that have failed the room temperature leak test and been disassembled, the O-rings displayed a compression set ranging from 51--95%. This is significantly greater than seen to date for packages inspected during KAMS field surveillance (23% average). For GLT O-rings, service life based on the room temperature leak rate criterion is comparable to that predicted by compression stress relaxation (CSR) data at higher temperatures (350--400 F). While there are no comparable failure data yet at aging temperatures below 300 F, extrapolations of the data for GLT O-rings suggests that CSR model predictions provide a conservative prediction of

  14. Silver plating technique seals leaks in thin wall tubing joints

    NASA Technical Reports Server (NTRS)

    Blenderman, W. H.

    1966-01-01

    Leaks in thin wall tubing joints are sealed by cleaning and silver plating the hot gas side of the joint in the leakage area. The pressure differential across the silver during hydrostatic test and subsequent use forces the ductile silver into the leak area and seals it.

  15. 10 CFR 39.35 - Leak testing of sealed sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... NUCLEAR REGULATORY COMMISSION LICENSES AND RADIATION SAFETY REQUIREMENTS FOR WELL LOGGING Equipment § 39.35 Leak testing of sealed sources. (a) Testing and recordkeeping requirements. Each licensee who uses... requirements. The following sealed sources are exempt from the periodic leak test requirements set out...

  16. 10 CFR 39.35 - Leak testing of sealed sources.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... NUCLEAR REGULATORY COMMISSION LICENSES AND RADIATION SAFETY REQUIREMENTS FOR WELL LOGGING Equipment § 39.35 Leak testing of sealed sources. (a) Testing and recordkeeping requirements. Each licensee who uses... requirements. The following sealed sources are exempt from the periodic leak test requirements set out...

  17. 10 CFR 39.35 - Leak testing of sealed sources.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... NUCLEAR REGULATORY COMMISSION LICENSES AND RADIATION SAFETY REQUIREMENTS FOR WELL LOGGING Equipment § 39.35 Leak testing of sealed sources. (a) Testing and recordkeeping requirements. Each licensee who uses... requirements. The following sealed sources are exempt from the periodic leak test requirements set out...

  18. 40 CFR 63.424 - Standards: Equipment leaks.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards: Equipment leaks. 63.424 Section 63.424 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS....424 Standards: Equipment leaks. (a) Each owner or operator of a bulk gasoline terminal or...

  19. 241-AY-102 Leak Detection Pit Drain Line Inspection Report

    SciTech Connect

    Boomer, Kayle D.; Engeman, Jason K.; Gunter, Jason R.; Joslyn, Cameron C.; Vazquez, Brandon J.; Venetz, Theodore J.; Garfield, John S.

    2014-01-20

    This document provides a description of the design components, operational approach, and results from the Tank AY-102 leak detection pit drain piping visual inspection. To perform this inspection a custom robotic crawler with a deployment device was designed, built, and operated by IHI Southwest Technologies, Inc. for WRPS to inspect the 6-inch leak detection pit drain line.

  20. HIGH RESOLUTION RESISTIVITY LEAK DETECTION DATA PROCESSING & EVALUATION MEHTODS & REQUIREMENTS

    SciTech Connect

    SCHOFIELD JS

    2007-10-04

    This document has two purposes: {sm_bullet} Describe how data generated by High Resolution REsistivity (HRR) leak detection (LD) systems deployed during single-shell tank (SST) waste retrieval operations are processed and evaluated. {sm_bullet} Provide the basic review requirements for HRR data when Hrr is deployed as a leak detection method during SST waste retrievals.

  1. 40 CFR 63.1255 - Standards: Equipment leaks.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... leaking connectors in the group of processes was less than 0.5 percent, but equal to or greater than 0.25... of processes was less than 0.25 percent during the initial or last required monitoring period. An... quarters. (v) For a group of processes with less than 0.25 percent leaking valves, the owner or...

  2. 40 CFR 63.1255 - Standards: Equipment leaks.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... leaking connectors in the group of processes was less than 0.5 percent, but equal to or greater than 0.25... of processes was less than 0.25 percent during the initial or last required monitoring period. An... quarters. (v) For a group of processes with less than 0.25 percent leaking valves, the owner or...

  3. 40 CFR 63.1363 - Standards for equipment leaks.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... percent, but equal to or greater than 0.25 percent, during the last required monitoring period, monitoring... leaking connectors in the group of process units was less than 0.25 percent during the last required... once every 4 quarters. (v) For a group of processes with less than 0.25 percent leaking valves,...

  4. 40 CFR 63.1255 - Standards: Equipment leaks.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... leaking connectors in the group of processes was less than 0.5 percent, but equal to or greater than 0.25... of processes was less than 0.25 percent during the initial or last required monitoring period. An... quarters. (v) For a group of processes with less than 0.25 percent leaking valves, the owner or...

  5. 40 CFR 63.1363 - Standards for equipment leaks.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... percent, but equal to or greater than 0.25 percent, during the last required monitoring period, monitoring... leaking connectors in the group of process units was less than 0.25 percent during the last required... once every 4 quarters. (v) For a group of processes with less than 0.25 percent leaking valves,...

  6. 40 CFR 63.1363 - Standards for equipment leaks.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... percent, but equal to or greater than 0.25 percent, during the last required monitoring period, monitoring... leaking connectors in the group of process units was less than 0.25 percent during the last required... once every 4 quarters. (v) For a group of processes with less than 0.25 percent leaking valves,...

  7. SEVENTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE

    SciTech Connect

    Daugherty, W.

    2012-08-30

    surveillance (24% average). For GLT O-rings, separate service life estimates have been made based on the O-ring fixture leak test data and based on compression stress relaxation (CSR) data. These two predictive models show reasonable agreement at higher temperatures (350 – 400 ºF). However, at 300 ºF, the room temperature leak test failures to date experienced longer aging times than predicted by the CSRbased model. This suggests that extrapolations of the CSR model predictions to temperatures below 300 ºF will provide a conservative prediction of service life relative to the leak rate criterion. Leak test failure data at lower temperatures are needed to verify this apparent trend. Insufficient failure data exist currently to perform a similar comparison for GLT-S O-rings. Aging and periodic leak testing will continue for the remaining PCV O-ring fixtures.

  8. Absolute calibration of optical flats

    DOEpatents

    Sommargren, Gary E.

    2005-04-05

    The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

  9. The Absolute Spectrum Polarimeter (ASP)

    NASA Technical Reports Server (NTRS)

    Kogut, A. J.

    2010-01-01

    The Absolute Spectrum Polarimeter (ASP) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from 30 GHz to 5 THz. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much greater than 1O(raised to the power of { -3}) and Compton distortion y < 10 (raised to the power of{-6}). We describe the ASP instrument and mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4 semiconductor bolometers.

  10. Physics of negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Abraham, Eitan; Penrose, Oliver

    2017-01-01

    Negative absolute temperatures were introduced into experimental physics by Purcell and Pound, who successfully applied this concept to nuclear spins; nevertheless, the concept has proved controversial: a recent article aroused considerable interest by its claim, based on a classical entropy formula (the "volume entropy") due to Gibbs, that negative temperatures violated basic principles of statistical thermodynamics. Here we give a thermodynamic analysis that confirms the negative-temperature interpretation of the Purcell-Pound experiments. We also examine the principal arguments that have been advanced against the negative temperature concept; we find that these arguments are not logically compelling, and moreover that the underlying "volume" entropy formula leads to predictions inconsistent with existing experimental results on nuclear spins. We conclude that, despite the counterarguments, negative absolute temperatures make good theoretical sense and did occur in the experiments designed to produce them.

  11. [Paravalvular leak following surgical valve replacement: is there a role for percutaneous paravalvular leak reduction?].

    PubMed

    Noble, S; lbrahim, R; Basmadjian, A; Müller, H; Lerch, R; Roffi, M

    2010-06-02

    After valve replacement, significant paravalvular leaks (PVL) may develop in up to 12.5% of the cases. Signs and symptoms include congestive heart failure and/or haemolysis and therefore may require reintervention. Redo valve surgery is considered the therapy of choice for symptomatic patients, either by valve replacement or leak repair. Considering the risk of morbidity and mortality associated with a surgical reintervention and the high post-surgical recurrence of PVL, the endovascular treatment represents an attractive alternative to surgery for high risk patients. The percutaneous approach aims at PVL reduction by implantation of certain occluder devices. The procedure is technically feasible in 60 to 90% of the cases according to different series. Technical success is associated with clinical improvement in 50 to 80% of the cases.

  12. Effect of leak location on measured respirator fit.

    PubMed

    Crutchfield, C D; Park, D L

    1997-06-01

    A significant difference in leak detection as a function of leak location was observed during a study assessing how well current models of quantitative fit-test systems detect leakage. Known sources of leakage (matched hypodermic needles) were introduced at three fixed locations into factory-probed half-mask and full-face respirators mounted on a headform-breathing machine system. The leak locations were the bridge of the nose, the cheek, and the chin. Baseline leakage into each respirator was determined by conducting a fit-test with all fixed leak sources capped. Fit tests were repeated with each individual source uncapped. Study objectives included determining (1) how well each system measured the leakage, and (2) whether leak location had any effect on leak measurement. An ambient aerosol fit-test system (Portacount Plus) and a controlled negative pressure (CNP) fit-test system (FitTester 3000) were used. The ambient aerosol system detected an overall average of 37.2% of the known leakage, with a coefficient of variation of 44.7%. An analysis of variance showed significant differences in aerosol system measurements of leakage as a function of leak location and mask type (p < 0.001). A different pattern of aerosol leak detection as a function of leak location was observed between half-mask and full-face respirators, which appears to be related to differences in in-mask airflow dynamics. The CNP system detected an overall average of 97.9% of the known leakage through the same hypodermic needles, with a coefficient of variation of 4.3%. CNP system results were not affected by leak location (p > 0.43) or mask type (p > 0.32).

  13. Intelligence Leaks: What Is the Role of the Leak and the Leaker in U.S. Democracy?

    DTIC Science & Technology

    2014-03-01

    between the Pentagon Papers and WikiLeaks to Edward Snowden. 14. SUBJECT TERMS Bradley Manning, Daniel Ellsberg, executive...35 1. Background ........................................................................................36 2. Bradley Manning... Bradley Manning provided thousands of secret government documents to WikiLeaks—to date the largest leak of classified documents in U.S. history.3 His

  14. Leak testing of cryogenic components — problems and solutions

    NASA Astrophysics Data System (ADS)

    Srivastava, S. P.; Pandarkar, S. P.; Unni, T. G.; Sinha, A. K.; Mahajan, K.; Suthar, R. L.

    2008-05-01

    A prototype of Cold Neutron Source (CNS) for Dhruva Reactor is being manufactured at Centre for Design and Manufacture (CDM), BARC, Mumbai for validating the mechanical and thermal engineering design aspects, besides checking the integrity of all joints and components at low temperature, 77K. Task of a Cold Neutron Source is to generate cold neutrons by cooling down the thermal neutrons, which are originally produced in a nuclear research reactor. The complete Cold Neutron Source system comprises a complex arrangement of moderator pot, transfer line (piping), pumps, refrigerators, storage tanks, a heat exchanger and associated controls and instrumentation. The heart of the system is moderator pot in which water (moderator) is cooled down by Liquid Nitrogen (LN2) being circulated through an annular cavity machined on the walls of the pot. Transfer lines for LN2 basically consist of two concentric Stainless Steel flexible pipes, which are joined to the inlet and outlet Aluminium tubes of the moderator pot through transition joints. Leak in any component may result in loss of liquid Nitrogen, degradation of vacuum, which in turn may affect the heat removal efficiency of the source. Hence, leak testing was considered a very important quality control tool and all joints and components were subjected to helium leak test using mass spectrometer leak detector (MSLD) at cryogenic temperature. During one of the earlier experiments, flow of LN2 through inner flexible pipe of the transfer line resulted in rise of pressure in the vacuum annulus and sweating on the outer flexible pipe. After investigations it was found that large thermal stress compounded with mechanical stress resulted in cracks in the inner pipe. Accordingly design was modified to get leak proof transfer line assembly. Further, during leak testing of thin wall moderator pot, gross leak was observed on the outer jacket welded joint. Leak was so large that even a small amount of Helium gas in the vicinity of the

  15. The detection of carbon dioxide leaks using quasi-tomographic laser absorption spectroscopy measurements in variable wind

    PubMed Central

    Levine, Zachary H.; Pintar, Adam L.; Dobler, Jeremy T.; Blume, Nathan; Braun, Michael; Scott Zaccheo, T.; Pernini, Timothy G.

    2016-01-01

    Laser absorption spectroscopy (LAS) has been used over the last several decades for the measurement of trace gasses in the atmosphere. For over a decade, LAS measurements from multiple sources and tens of retroreflectors have been combined with sparse-sample tomography methods to estimate the 2-D distribution of trace gas concentrations and underlying fluxes from point-like sources. In this work, we consider the ability of such a system to detect and estimate the position and rate of a single point leak which may arise as a failure mode for carbon dioxide storage. The leak is assumed to be at a constant rate giving rise to a plume with a concentration and distribution that depend on the wind velocity. We demonstrate the ability of our approach to detect a leak using numerical simulation and also present a preliminary measurement. PMID:27453761

  16. Pharmaceutical container/closure integrity. IV: Development of an indirect correlation between vacuum decay leak measurement and microbial ingress.

    PubMed

    Nguyen, L T; Muangsiri, W; Schiere, R; Guazzo, D K; Kirsch, L E

    1999-01-01

    The rational development of a physical test method to evaluate the microbial barrier properties of sterile containers necessitates its correlation to microbiological exclusion. This can be accomplished by direct or indirect correlation. In the former, the proposed physical test is directly compared to microbial challenges using appropriate test units that stimulate container leaks at both high and low probabilities of microbial ingress. Previous work has demonstrated the development of a direct correlation using helium leak rate methods and microbial immersion challenges. An indirect correlation can be established by comparing the proposed physical method to well-defined leakage standards that represent various known levels of microbial ingress. Thus the quality assurance properties of a physical test method can be established by comparison to another physical test method that has been previously characterized. This approach has the distinct advantages of being faster, quantitatively rigorous, and less subject to the vicissitudes, of microbial testing. This approach was demonstrated by comparing the helium leak rate method to vacuum decay testing. Additionally it was demonstrated that vacuum decay testing was a fast and reproducible method for detecting leaks of about 1 to 2 mm. Leaks were simulated by affixing micropipettes into glass vials.

  17. C2H2 absolutely optical frequency-stabilized and 40 GHz repetition-rate-stabilized, regeneratively mode-locked picosecond erbium fiber laser at 1.53 microm.

    PubMed

    Nakazawa, Masataka; Kasai, Keisuke; Yoshida, Masato

    2008-11-15

    We have succeeded in the simultaneous stabilization of the optical frequency and repetition rate of a regeneratively mode-locked picosecond erbium-doped fiber ring laser. The optical frequency was locked to the molecular absorption of C2H2 in the 1.5 microm band, and the repetition rate was stabilized to a 40 GHz synthesizer by using a microwave phase-locked loop. The optical frequency stability of the pulse train reached 2x10(-11) for tau=10-100 s. The key to success is the independent control of the repetition rate without disturbing the optical cavity condition.

  18. Resilience to leaking--dynamic systems modeling of information security.

    PubMed

    Hamacher, Kay

    2012-01-01

    Leaking of confidential material is a major threat to information security within organizations and to society as a whole. This insight has gained traction in the political realm since the activities of Wikileaks, which hopes to attack 'unjust' systems or 'conspiracies'. Eventually, such threats to information security rely on a biologistic argument on the benefits and drawbacks that uncontrolled leaking might pose for 'just' and 'unjust' entities. Such biological metaphors are almost exclusively based on the economic advantage of participants. Here, I introduce a mathematical model of the complex dynamics implied by leaking. The complex interactions of adversaries are modeled by coupled logistic equations including network effects of econo-communication networks. The modeling shows, that there might arise situations where the leaking envisioned and encouraged by Wikileaks and the like can strengthen the defending entity (the 'conspiracy'). In particular, the only severe impact leaking can have on an organization seems to originate in the exploitation of leaks by another entity the organization competes with. Therefore, the model suggests that leaks can be used as a `tactical mean' in direct adversary relations, but do not necessarily increase public benefit and societal immunization to 'conspiracies'. Furthermore, within the model the exploitation of the (open) competition between entities seems to be a more promising approach to control malicious organizations : divide-et-impera policies triumph here.

  19. Development of perfluorocarbon tracer technology for underground leak location.

    PubMed

    Hassoun, S; McBride, T; Russell, D A

    2000-10-01

    A method has been developed for the atmospheric sampling and analysis of four perfluorocarbon tracer (PFT) compounds simultaneously at the parts per trillion (ppt) level. PFTs were pre-concentrated using adsorbent tube air sampling. Analysis was achieved by thermal desorption (TD) and gas chromatography (GC) with electron capture detection (ECD). Efficient separation of the PFTs from the other sample constituents was achieved by use of a capillary porous layer open tubular (PLOT) GC column without the need to cool the GC oven to sub-ambient temperatures using liquid coolants (M. de Bortoli and E. Pecchio, J. High Resolut. Chromatogr., 1985, 8, 422) or for a catalytic destruction step to remove interferents (T. W. D'Ottavio, R. W. Goodrich and R. N. Dietz, Environ. Sci. Technol., 1986, 20, 100). Results from test field trials with two volatile PFTs that were buried to simulate an underground leaking cable were successful. The PFTs were detected above ground level to pinpoint the leak position. The highest tracer concentrations were detected within 1 m of the simulated leak positions 2 days after tracer burial. The developed technology was applied to an oil leaking high voltage electricity cable. One PFT was added to the cable oil which enabled detection of the oil leak to within 3 m. The reported method has many advantages over currently used leak detection methods and could, in the future, be applied to the detection of underground leaks in a variety of cables and pipes.

  20. Autogenous Metallic Pipe Leak Repair in Potable Water Systems.

    PubMed

    Tang, Min; Triantafyllidou, Simoni; Edwards, Marc A

    2015-07-21

    Copper and iron pipes have a remarkable capability for autogenous repair (self-repair) of leaks in potable water systems. Field studies revealed exemplars that metallic pipe leaks caused by nails, rocks, and erosion corrosion autogenously repaired, as confirmed in the laboratory experiments. This work demonstrated that 100% (N = 26) of 150 μm leaks contacting representative bulk potable water in copper pipes sealed autogenously via formation of corrosion precipitates at 20-40 psi, pH 3.0-11.0, and with upward and downward leak orientations. Similar leaks in carbon steel pipes at 20 psi self-repaired at pH 5.5 and 8.5, but two leaks did not self-repair permanently at pH 11.0 suggesting that water chemistry may control the durability of materials that seal the leaks and therefore the permanence of repair. Larger 400 μm holes in copper pipes had much lower (0-33%) success of self-repair at pH 3.0-11.0, whereas all 400 μm holes in carbon steel pipes at 20 psi self-repaired at pH 4.0-11.0. Pressure tests indicated that some of the repairs created at 20-40 psi ambient pressure could withstand more than 100 psi without failure. Autogenous repair has implications for understanding patterns of pipe failures, extending the lifetime of decaying infrastructure, and developing new plumbing materials.

  1. Resilience to Leaking — Dynamic Systems Modeling of Information Security

    PubMed Central

    Hamacher, Kay

    2012-01-01

    Leaking of confidential material is a major threat to information security within organizations and to society as a whole. This insight has gained traction in the political realm since the activities of Wikileaks, which hopes to attack ‘unjust’ systems or ‘conspiracies’. Eventually, such threats to information security rely on a biologistic argument on the benefits and drawbacks that uncontrolled leaking might pose for ‘just’ and ‘unjust’ entities. Such biological metaphors are almost exclusively based on the economic advantage of participants. Here, I introduce a mathematical model of the complex dynamics implied by leaking. The complex interactions of adversaries are modeled by coupled logistic equations including network effects of econo-communication networks. The modeling shows, that there might arise situations where the leaking envisioned and encouraged by Wikileaks and the like can strengthen the defending entity (the ‘conspiracy’). In particular, the only severe impact leaking can have on an organization seems to originate in the exploitation of leaks by another entity the organization competes with. Therefore, the model suggests that leaks can be used as a `tactical mean’ in direct adversary relations, but do not necessarily increase public benefit and societal immunization to ‘conspiracies’. Furthermore, within the model the exploitation of the (open) competition between entities seems to be a more promising approach to control malicious organizations : divide-et-impera policies triumph here. PMID:23227151

  2. Absolute calibration of optical tweezers

    SciTech Connect

    Viana, N.B.; Mazolli, A.; Maia Neto, P.A.; Nussenzveig, H.M.; Rocha, M.S.; Mesquita, O.N.

    2006-03-27

    As a step toward absolute calibration of optical tweezers, a first-principles theory of trapping forces with no adjustable parameters, corrected for spherical aberration, is experimentally tested. Employing two very different setups, we find generally very good agreement for the transverse trap stiffness as a function of microsphere radius for a broad range of radii, including the values employed in practice, and at different sample chamber depths. The domain of validity of the WKB ('geometrical optics') approximation to the theory is verified. Theoretical predictions for the trapping threshold, peak position, depth variation, multiple equilibria, and 'jump' effects are also confirmed.

  3. Modeling and locating underground water pipe leak with microseismic data

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Liu, Jiangping; Liu, Hao; Tian, Zhijian; Cheng, Fei

    2017-01-01

    Traditional pipeline leak locating methods require that geophones have to be placed on the pipe wall. While if the exact location of the pipeline is unknown, the leaks may not be identified accurately. To solve this problem, considering the characteristics of pipeline leak, a continuous random seismic source model is proposed and geological models are established. Based on the two dimensional (2D) viscoacoustic equations and the staggered grid finite-difference (FD) algorithm, the microseismic wave field generated by a leaking pipe is modeled. Cross-correlation analysis and the simulated annealing (SA) algorithm are employed to obtain the time difference and the leak location. Analysis and discussions of the effects of number of recorded traces, survey layout, and offset and trace interval on the accuracy of the estimated location are also conducted. Simulation and data field experiment results indicate that: (1) A continuous random source can realistically represent the leak microseismic wave field in a simulation using 2D viscoacoustic equations and staggered grid FD algorithm. (2) For the leak microseismic wave field, the cross-correlation method is effective for calculating time difference of the direct wave relative to the reference trace. However, outside the refraction blind zone, accuracy of the time difference is reduced by the effects of refracted wave. (3) The SA algorithm based upon time difference, helps to identify the leak location effectively, even in the presence of noise. Estimation of the horizontal distance is more accurate than that of the depth, and the locating errors increase with increasing number of traces and offset. Moreover, in the refraction blind zone, trace interval has almost no impact on the accuracy of the location estimate. And the symmetrical array provides a higher estimate accuracy than the asymmetrical array. (4) The acquisition method of time difference based on the microseismic theory and SA algorithm has a great potential

  4. Endoscopic management of patients with post-surgical leaks involving the gastrointestinal tract: A large case series

    PubMed Central

    Caruso, Angelo; Cellini, Carlo; Sica, Mariano; Zullo, Angelo; Mirante, Vincenzo Giorgio; Bertani, Helga; Frazzoni, Marzio; Mutignani, Massimiliano; Galloro, Giuseppe; Conigliaro, Rita

    2016-01-01

    Background Post-surgical anastomotic leaks often require a re-intervention, are associated with a definite morbidity and mortality, and with relevant costs. We described a large series of patients with different post-surgical leaks involving the gastrointestinal tract managed with endoscopy as initial approach. Methods This was a retrospective analysis of prospectively collected cases with anastomotic leaks managed with different endoscopic approaches (with surgical or radiological drainage when needed) in two endoscopic centres during 5 years. Interventions included: (1) over-the-scope clip (OTSC) positioning; (2) placement of a covered self-expanding metal stent (SEMS); (3) fibrin glue injection (Tissucol); and (4) endo-sponge application, according to both the endoscopic feature and patient’s status. Results A total of 76 patients underwent endoscopic treatment for a leak either in the upper (47 cases) or lower (29 cases) gastrointestinal tract, and the approach was successful in 39 (83%) and 22 (75.9%) patients, respectively, accounting for an overall 80.3% success rate. Leak closure was achieved in 84.9% and 78.3% of patients managed by using a single or a combination of endoscopic devices. Overall, leak closure failed in 15 (19.7%) patients, and the surgical approach was successful in all 14 patients who underwent re-intervention, whilst one patient died due to sepsis at 7 days. Conclusions Our data suggest that an endoscopic approach, with surgical or radiological drainage when needed, is successful and safe in the majority of patients with anastomotic gastrointestinal leaks. Therefore, an endoscopic treatment could be attempted before resorting to more invasive, costly and risky re-intervention.

  5. The cuff-leak test: what are we measuring?

    PubMed

    De Backer, Daniel

    2005-02-01

    Stridor is one of the most frequent causes of early extubation failure. The cuff-leak test may help to identify patients at risk to develop post-extubation laryngeal edema. However the discrimination power of the cuff-leak test is highly variable and can be use, at best, to detect patients at risk to develop edema but should not be used to postpone extubation as tracheal extubation can still be successful in many patients with a positive test. In this editorial, the author discuss the factors influencing the leak and hence its predictive value.

  6. Quartz enhanced photoacoustic leak sensor for mechatronic components

    NASA Astrophysics Data System (ADS)

    Sampaolo, A.; Patimisco, P.; Giglio, M.; Calabrese, P. P.; Chieco, L.; Scamarcio, G.; Tittel, F. K.; Spagnolo, V.

    2016-02-01

    We report the first demonstration of a leak sensor based on a mid-IR quartz-enhanced photoacoustic (QEPAS) spectroscopic technique. A QEPAS sensor was integrated in a vacuum seal test station for mechatronic components. The laser source is a quantum cascade laser emitting at 10.56 μm, resonant with a strong absorption band of sulfur hexafluoride (SF6), which was selected as target gas for leak detection. The minimum detectable concentration of the QEPAS sensor is 6.9 ppb with an integration time of 1 s. This detection sensitivity allowed to measure SF6 leak flows as low as 3x10-5 standard cm3.

  7. Leak detection system upgrades Cochin pipeline

    SciTech Connect

    Wray, B.; O`Leary, C.

    1996-02-01

    Amoco Canada`s Cochin pipeline system consists of 1,900 miles of 12-inch pipeline, 31 pump stations, eight injection/delivery stations and five propane terminals. It originates just northeast of Edmonton and crosses into the US in North Dakota, runs south of Lake Michigan, turns northeast to pass through Detroit and terminates in Sarnia, Ontario. In 1991, it was decided to significantly upgrade facilities for operating the Cochin pipeline. The control center hardware was obsolete, including parts and components no longer available. Also, SCADA and modeling software was no longer supported by outside vendors or consultants and there was only limited in-house support available. The land-based communications system was unreliable and expensive. Goals for the upgrade project included maintaining (improving) reliability and minimizing operating risks. Amoco Canada wanted to ensure reliable operations and support, provide reliable and effective leak detection, establish dependable communications, have the capability to respond to market additions or changes and maintain customer and regulatory confidence. Another important goal was to minimize operating costs. Specifically, methods were sought to minimize power costs, communications expense and support and maintenance expenditures while eliminating non-productive work. This paper reviews the resulting design and performance of this system.

  8. Effects of a documented hydrogen fluoride leak

    SciTech Connect

    Feder, W.A.

    1985-01-01

    At about 6 a.m. on June 19, 1984, 1037 liters of pressurized HF liquid escaped from a storage tank through a 2 mm diameter hole. 48 hours after the leak was discovered and sealed, visible injury to vegetation was observed 2 miles downwind of the source in a tear drop pattern. Injury symptoms ranged from a slight browning of leaves and needles to death of twigs and leaves and needles. Poplar, white pine, spruce, oak, red maple and several herbaceous plant species were injured. Ragweed was not injured but sensitive fern was severely injured. Goldenrod was also injured but recovered within 3 weeks after exposure. White pine trees within 1/4 of a mile from the source were killed. Fluoride analysis of tissues from upwind and downwind trees and herbaceous plants revealed fluoride tissue levels ranging from 5 to 34,000 ppm. Examples of distance/concentration are given. Soils revealed fluoride levels of about 1 ppm at all locations.

  9. Low heat leak connector for cryogenic system

    NASA Technical Reports Server (NTRS)

    Stelts, P. D. (Inventor)

    1965-01-01

    Heat leak from the surrounding atmosphere during fluid transfer from a spaced shell-insulated vessel for storing liquified gas having an upper gaseous phase, in minimized by forming a relatively wide, shallow blister on the wall of the vessel at the point of transfer line connection. The shell and the opposed walls of the blister have aligned openings whose common axis passes centrally through the blister and is normal to the surfaces of the vessel and shell. A fluid transfer line conduit passing through the shell opening is in fluid-tight connection with the shell and blister wall. The fluid transfer line confines the fluid in a continuous stream. The blister is filled with a heat insulating material which provides a thermal break between the central wall portions of the blister. A connector at the bottom of the vessel comprises a tube extending between the openings in the blister which projects a short distance within the body of liquefied gas and terminates in a reverse bend to prevent backflow of liquid through the pipe.

  10. The absolute threshold of cone vision

    PubMed Central

    Koeing, Darran; Hofer, Heidi

    2013-01-01

    We report measurements of the absolute threshold of cone vision, which has been previously underestimated due to sub-optimal conditions or overly strict subjective response criteria. We avoided these limitations by using optimized stimuli and experimental conditions while having subjects respond within a rating scale framework. Small (1′ fwhm), brief (34 msec), monochromatic (550 nm) stimuli were foveally presented at multiple intensities in dark-adapted retina for 5 subjects. For comparison, 4 subjects underwent similar testing with rod-optimized stimuli. Cone absolute threshold, that is, the minimum light energy for which subjects were just able to detect a visual stimulus with any response criterion, was 203 ± 38 photons at the cornea, ∼0.47 log units lower than previously reported. Two-alternative forced-choice measurements in a subset of subjects yielded consistent results. Cone thresholds were less responsive to criterion changes than rod thresholds, suggesting a limit to the stimulus information recoverable from the cone mosaic in addition to the limit imposed by Poisson noise. Results were consistent with expectations for detection in the face of stimulus uncertainty. We discuss implications of these findings for modeling the first stages of human cone vision and interpreting psychophysical data acquired with adaptive optics at the spatial scale of the receptor mosaic. PMID:21270115

  11. Sodium leak channel, non-selective contributes to the leak current in human myometrial smooth muscle cells from pregnant women

    PubMed Central

    Reinl, Erin L.; Cabeza, Rafael; Gregory, Ismail A.; Cahill, Alison G.; England, Sarah K.

    2015-01-01

    Uterine contractions are tightly regulated by the electrical activity of myometrial smooth muscle cells (MSMCs). These cells require a depolarizing current to initiate Ca2+ influx and induce contraction. Cationic leak channels, which permit a steady flow of cations into a cell, are known to cause membrane depolarization in many tissue types. Previously, a Gd3+-sensitive, Na+-dependent leak current was identified in the rat myometrium, but the presence of such a current in human MSMCs and the specific ion channel conducting this current was unknown. Here, we report the presence of a Na+-dependent leak current in human myometrium and demonstrate that the Na+-leak channel, NALCN, contributes to this current. We performed whole-cell voltage-clamp on fresh and cultured MSMCs from uterine biopsies of term, non-laboring women and isolated the leak currents by using Ca2+ and K+ channel blockers in the bath solution. Ohmic leak currents were identified in freshly isolated and cultured MSMCs with normalized conductances of 14.6 pS/pF and 10.0 pS/pF, respectively. The myometrial leak current was significantly reduced (P < 0.01) by treating cells with 10 μM Gd3+ or by superfusing the cells with a Na+-free extracellular solution. Reverse transcriptase PCR and immunoblot analysis of uterine biopsies from term, non-laboring women revealed NALCN messenger RNA and protein expression in the myometrium. Notably, ∼90% knockdown of NALCN protein expression with lentivirus-delivered shRNA reduced the Gd3+-sensitive leak current density by 42% (P < 0.05). Our results reveal that NALCN, in part, generates the leak current in MSMCs and provide the basis for future research assessing NALCN as a potential molecular target for modulating uterine excitability. PMID:26134120

  12. Sodium leak channel, non-selective contributes to the leak current in human myometrial smooth muscle cells from pregnant women.

    PubMed

    Reinl, Erin L; Cabeza, Rafael; Gregory, Ismail A; Cahill, Alison G; England, Sarah K

    2015-10-01

    Uterine contractions are tightly regulated by the electrical activity of myometrial smooth muscle cells (MSMCs). These cells require a depolarizing current to initiate Ca(2+) influx and induce contraction. Cationic leak channels, which permit a steady flow of cations into a cell, are known to cause membrane depolarization in many tissue types. Previously, a Gd(3+)-sensitive, Na(+)-dependent leak current was identified in the rat myometrium, but the presence of such a current in human MSMCs and the specific ion channel conducting this current was unknown. Here, we report the presence of a Na(+)-dependent leak current in human myometrium and demonstrate that the Na(+)-leak channel, NALCN, contributes to this current. We performed whole-cell voltage-clamp on fresh and cultured MSMCs from uterine biopsies of term, non-laboring women and isolated the leak currents by using Ca(2+) and K(+) channel blockers in the bath solution. Ohmic leak currents were identified in freshly isolated and cultured MSMCs with normalized conductances of 14.6 pS/pF and 10.0 pS/pF, respectively. The myometrial leak current was significantly reduced (P < 0.01) by treating cells with 10 μM Gd(3+) or by superfusing the cells with a Na(+)-free extracellular solution. Reverse transcriptase PCR and immunoblot analysis of uterine biopsies from term, non-laboring women revealed NALCN messenger RNA and protein expression in the myometrium. Notably, ∼90% knockdown of NALCN protein expression with lentivirus-delivered shRNA reduced the Gd(3+)-sensitive leak current density by 42% (P < 0.05). Our results reveal that NALCN, in part, generates the leak current in MSMCs and provide the basis for future research assessing NALCN as a potential molecular target for modulating uterine excitability.

  13. Age and forgetfulness: absolute versus comparison decisions about capability.

    PubMed

    Erber, J T; Prager, I G

    1997-01-01

    Perceivers were assigned to one of two decision conditions. In an absolute decision condition, perceivers rated how likely they would be to allow a young or old highly forgetful, slightly forgetful, or nonforgetful target to perform a challenging task. In a comparison decision condition, perceivers rated two targets, one young and one old, who had a similar level of forgetfulness. Separate Decision Type x Target Forgetfulness analyses of variance were conducted on ratings of the two target age groups. Young targets received higher ratings in the comparison than in the absolute condition, whereas old targets were rated the same in the two conditions. There was some preference for young targets in a comparison situation, but it was concluded that forgetfulness was a more important factor than age in perceivers' ratings.

  14. Optimal control of fuel overpressure in a polymer electrolyte membrane fuel cell with hydrogen transfer leak during load change

    NASA Astrophysics Data System (ADS)

    Ebadighajari, Alireza; DeVaal, Jake; Golnaraghi, Farid

    2017-02-01

    Formation of membrane pinholes is a common defect in fuel cells, inflicting more cost and making less durable cells. This work focuses on mitigating this issue, and offers a continuous online treatment instead of attempting to dynamically model the hydrogen transfer leak rate. This is achieved by controlling the differential pressure between the anode and cathode compartments at the inlet side of the fuel cell stack, known as the fuel overpressure. The model predictive control approach is used to attain the objectives in a Ballard 9-cell Mk1100 polymer electrolyte membrane fuel cell (PEMFC) with inclusion of hydrogen transfer leak. Furthermore, the pneumatic modeling technique is used to model the entire anode side of a fuel cell station. The hydrogen transfer leak is embedded in the model in a novel way, and is considered as a disturbance during the controller design. Experimental results for different sizes of hydrogen transfer leaks are provided to show the benefits of fuel overpressure control system in alleviating the effects of membrane pinholes, which in turn increases membrane longevity, and reduces hydrogen emissions in the eventual presence of transfer leaks. Moreover, the model predictive controller provides an optimal control input while satisfying the problem constraints.

  15. Reinvestigation of the laser-initiated Cl/sub 2//HBr chain reaction: absolute rate constants and the v = 2/v = 1 ratio from Cl + HBr. -->. HCl(v) + Br

    SciTech Connect

    Dolson, D.A.; Leone, S.R.

    1987-06-18

    The Cl/sub 2//HBr chain reaction is reinvestigated by using real time state-selected observations of ..delta..v = -1 chemiluminescence from the HCl(V) products following pulsed laser photolysis of Cl/sub 2/. These state-selected observations are analyzed with a more complete kinetic treatment to obtain room temperature rate constants for the chain propagation steps and the vibrational deactivation of HCl(V = 1,2) by HBr. The chain propagation rate constants are k/sub R1/ = (1.02 +/- 0.15) x 10/sup -11/ and k/sub R2/ = (1.1 +/- 0.4) x 10/sup -15/ cm/sup 3/ molecule/sup -1/ s/sup -1/, respectively, for Cl + HBr ..-->../sup kR1/ HCl(v) + Br and Br + Cl/sub 2/ ..-->../sup kR2/ BrCl + Cl. Rate constants for vibrational deactivation of HCl(v=1) and HCl(v=2) by HBr are k/sub V1/ = (1.06 +/- 0.16) x 10/sup -12/ and k/sub V2/ = (2.09 +/- 0.50) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/. Relative intensity measurements of the HCl v = 2 ..-->.. 1 and 1 ..-->.. 0 vibrational fluorescence are used to obtain an HCl(v) product branching ratio, N/sub v=2//N/sub v=1/ = 0.40 +/- 0.06. The kinetic analysis indicates that broad-band observations of infrared chemiluminescence may lead to erroneous rate constant determinations because of vibrational cascade, whereas the detection of individual vibrational states leads to correct results.

  16. The reaction NH2 + PH3 yields NH3 + PH2 - Absolute rate constant measurement and implication for NH3 and PH3 photochemistry in the atmosphere of Jupiter

    NASA Technical Reports Server (NTRS)

    Bosco, S. R.; Brobst, W. D.; Nava, D. F.; Stief, L. J.

    1983-01-01

    The rate constant is measured over the temperature interval 218-456 K using the technique of flash photolysis-laser-induced fluorescence. NH2 radicals are produced by the flash photolysis of ammonia highly diluted in argon, and the decay of fluorescent NH2 photons is measured by multiscaling techniques. For each of the five temperatures employed in the study, the results are shown to be indepenent of variations in PH3 concentration, total pressure (argon), and flash intensity. It is found that the rate constant results are best represented for T between 218 and 456 K by the expression k = (1.52 + or - 0.16) x 10 to the -12th exp(-928 + or - 56/T) cu cm per molecule per sec; the error quoted is 1 standard deviation. This is the first determination of the rate constant for the reaction NH2 + PH3. The data are compared with an estimate made in order to explain results of the radiolysis of NH3-PH3 mixtures. The Arrhenius parameters determined here for NH2 + PH3 are then contrasted with those for the corresponding reactions of H and OH with PH3.

  17. The reaction NH2 + PH3 yields NH3 + PH2: Absolute rate constant measurement and implication for NH3 and PH3 photochemistry in the atmosphere of Jupiter

    NASA Technical Reports Server (NTRS)

    Bosco, S. R.; Brobst, W. D.; Nava, D. F.; Stief, L. J.

    1983-01-01

    The rate constant is measured over the temperature interval 218-456 K using the technique of flash photolysis-laser-induced fluorescence. NH2 radicals are produced by the flash photolysis of ammonia highly diluted in argon, and the decay of fluorescent NH2 photons is measured by multiscaling techniques. For each of the five temperatures employed in the study, the results are shown to be independent of variations in PH3 concentration, total pressure (argon), and flash intensity. It is found that the rate constant results are best represented for T between 218 and 456 K by the expression k = (1.52 + or - 0.16) x 10 to the -12th exp(-928 + or - 56/T) cu cm per molecule per sec; the error quoted is 1 standard deviation. This is the first determination of the rate constant for the reaction NH2 + PH3. The data are compared with an estimate made in order to explain results of the radiolysis of NH3-PH3 mixtures. The Arrhenius parameters determined here for NH2 + PH3 are then constrasted with those for the corresponding reactions of H and OH with PH3.

  18. 40 CFR 63.648 - Equipment leak standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (except for the agitator provisions). The leak definition for valves, connectors, and instrumentation... service and agitators in heavy liquid service, owners and operators are not required to comply with...

  19. 40 CFR 63.648 - Equipment leak standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (except for the agitator provisions). The leak definition for valves, connectors, and instrumentation... service and agitators in heavy liquid service, owners and operators are not required to comply with...

  20. 40 CFR 63.648 - Equipment leak standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (except for the agitator provisions). The leak definition for valves, connectors, and instrumentation... service and agitators in heavy liquid service, owners and operators are not required to comply with...

  1. 40 CFR 63.648 - Equipment leak standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (except for the agitator provisions). The leak definition for valves, connectors, and instrumentation... service and agitators in heavy liquid service, owners and operators are not required to comply with...

  2. 40 CFR 63.648 - Equipment leak standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (except for the agitator provisions). The leak definition for valves, connectors, and instrumentation... service and agitators in heavy liquid service, owners and operators are not required to comply with...

  3. Numerical Simulation of Gas Leaking Diffusion from Storage Tank

    NASA Astrophysics Data System (ADS)

    Zhu, Hongjun; Jing, Jiaqiang

    Over 80 percents of storage tank accidents are caused by gas leaking. Since traditional empirical calculation has great errors, present work aims to study the gas leaking diffusion under different wind conditions by numerical simulation method based on computational fluid dynamics theory. Then gas concentration distribution was obtained to determine the scope of the security zone. The results showed that gas diffused freely along the axis of leaking point without wind, giving rise to large range of hazardous area. However, wind plays the role of migrating and diluting the leaking gas. The larger is the wind speed, the smaller is the damage and the bigger is the security zone. Calculation method and results can provide some reference to establish and implement rescue program for accidents.

  4. 40 CFR 61.135 - Standard: Equipment leaks.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Emissions from Coke By-Product Recovery Plants § 61.135 Standard: Equipment leaks. (a) Each owner or... system that purges the barrier fluid into a process stream with zero benzene emissions to the...

  5. 40 CFR 61.135 - Standard: Equipment leaks.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Emissions from Coke By-Product Recovery Plants § 61.135 Standard: Equipment leaks. (a) Each owner or... system that purges the barrier fluid into a process stream with zero benzene emissions to the...

  6. 40 CFR 61.135 - Standard: Equipment leaks.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Emissions from Coke By-Product Recovery Plants § 61.135 Standard: Equipment leaks. (a) Each owner or... system that purges the barrier fluid into a process stream with zero benzene emissions to the...

  7. 40 CFR 61.135 - Standard: Equipment leaks.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Emissions from Coke By-Product Recovery Plants § 61.135 Standard: Equipment leaks. (a) Each owner or... system that purges the barrier fluid into a process stream with zero benzene emissions to the...

  8. 40 CFR 61.135 - Standard: Equipment leaks.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Emissions from Coke By-Product Recovery Plants § 61.135 Standard: Equipment leaks. (a) Each owner or... system that purges the barrier fluid into a process stream with zero benzene emissions to the...

  9. Clinical challenges of persistent pulmonary air-leaks--case report.

    PubMed

    van Zeller, M; Bastos, P; Fernandes, G; Magalhães, A

    2014-01-01

    Air leaks are a common problem after pulmonary resection and can be a source of significant morbidity and mortality. The authors describe the case of a 68-year-old male patient who presented with a persistent air-leak after pulmonary resection. Watchful waiting, surgical procedures, as well as medical therapy like pleurodesis and implantation of endobronchial one-way valves on the bronchial segments identified using systematic occlusion of the bronchial segments, were all tried unsuccessfully. During that time the patient remained hospitalized with a chest tube. The instillation of methylene blue through the chest tube was used to identify the segments leading to the persistent air-leak; this enabled successful endobronchial valve placement which sufficiently reduced the size of the air-leak so that the chest tube could be removed. Nonsurgical approaches seem promising and, for some patients may be the only treatment option after all conventional treatments have failed or are considered too high risk.

  10. An ultrasonic array sensor for spacecraft leak direction finding.

    PubMed

    Holland, Stephen D; Roberts, Ron; Chimenti, D E; Song, Jun Ho

    2006-12-01

    We have developed an ultrasonic array sensor useable for locating air leaks in manned spacecraft and have found that this sensor locates leaks in a 1-m(2) plate to within 2 cm. The sensor consists of a 63-element multiplexed array plus a reference element, all constructed from a single PZT disc and a printed circuit board. Cross-correlations of signals from the array elements with signals from the single reference element provide a measurement of the leak noise passing through the spacecraft skin under the array. A spatial Fourier transform reveals the dominant direction of propagation. Triangulation from multiple sensor locations can be used to find the source of the leak.

  11. Thermographic Leak Detection of the Space Shuttle Main Engine Nozzle

    NASA Technical Reports Server (NTRS)

    Walker, James L.; Russell, Samuel S.

    1999-01-01

    The Space Shuttle Main Engines Nozzles consist of over one thousand tapered Inconel coolant tubes brazed to a stainless steel structural jacket. Liquid Hydrogen flows through the tubing, from the aft to forward end of the nozzle, under high pressure to maintain a thermal balance between the rocket exhaust and the nozzle wall. Three potential problems occur within the SSME nozzle coolant tubes as a result of manufacturing anomalies and the highly volatile service environment including poor or incomplete bonding of the tubes to the structural jacket, cold wall leaks and hot wall leaks. Of these conditions the identification of cold wall leaks has been the most problematic. The methods and results presented in this summary addresses the thermographic identification of cold wall "interstitial" leaks between the structural jacket and coolant tubes of the Space Shuttle Main Engines Nozzles.

  12. Standard Test Procedures for Evaluating Various Leak Detection Methods

    EPA Pesticide Factsheets

    Learn about protocols that testers could use to demonstrate that an individual release detection equipment type could meet the performance requirements noted in the federal UST requirements for detecting leaks.

  13. Minimally Invasive, Nonsurgical Approach to Repairing Mitral Valve Leaks

    MedlinePlus

    Minimally Invasive, Nonsurgical Approach to Repairing Mitral Valve Leaks - David X. Zhao, MD Click Here to view the BroadcastMed, Inc. Privacy Policy and Legal Notice © 2017 BroadcastMed, Inc. All rights ...

  14. The detection of carbon dioxide leaks using quasi-tomographic laser absorption spectroscopy measurements in variable wind

    DOE PAGES

    Levine, Zachary H.; Pintar, Adam L.; Dobler, Jeremy T.; ...

    2016-04-13

    Laser absorption spectroscopy (LAS) has been used over the last several decades for the measurement of trace gasses in the atmosphere. For over a decade, LAS measurements from multiple sources and tens of retroreflectors have been combined with sparse-sample tomography methods to estimate the 2-D distribution of trace gas concentrations and underlying fluxes from point-like sources. In this work, we consider the ability of such a system to detect and estimate the position and rate of a single point leak which may arise as a failure mode for carbon dioxide storage. The leak is assumed to be at a constant ratemore » giving rise to a plume with a concentration and distribution that depend on the wind velocity. We demonstrate the ability of our approach to detect a leak using numerical simulation and also present a preliminary measurement.« less

  15. FHF-independent conduction of action potentials along the leak-resistant cerebellar granule cell axon

    PubMed Central

    Dover, Katarzyna; Marra, Christopher; Solinas, Sergio; Popovic, Marko; Subramaniyam, Sathyaa; Zecevic, Dejan; D'Angelo, Egidio; Goldfarb, Mitchell

    2016-01-01

    Neurons in vertebrate central nervous systems initiate and conduct sodium action potentials in distinct subcellular compartments that differ architecturally and electrically. Here, we report several unanticipated passive and active properties of the cerebellar granule cell's unmyelinated axon. Whereas spike initiation at the axon initial segment relies on sodium channel (Nav)-associated fibroblast growth factor homologous factor (FHF) proteins to delay Nav inactivation, distal axonal Navs show little FHF association or FHF requirement for high-frequency transmission, velocity and waveforms of conducting action potentials. In addition, leak conductance density along the distal axon is estimated as <1% that of somatodendritic membrane. The faster inactivation rate of FHF-free Navs together with very low axonal leak conductance serves to minimize ionic fluxes and energetic demand during repetitive spike conduction and at rest. The absence of FHFs from Navs at nodes of Ranvier in the central nervous system suggests a similar mechanism of current flux minimization along myelinated axons. PMID:27666389

  16. Operator-related risk factors of anastomotic leaks after colorectal surgery: an up-to-date

    PubMed Central

    CAZIUC, ALEXANDRA; DINDELEGAN, GEORGE CALIN; MIRONIUC, AUREL

    2015-01-01

    Digestive fistulas are a major complication after digestive surgery. Anastomotic leakage increases the hospitalization time, the prognosis and survival rate after colorectal surgical interventions. The factors involved are either systemic (determined by the patients’ co-morbidities), or local (vicious surgical technique or the injuries produced by the disease that requires the anastomosis). Although there are many studies regarding the risk factors of anastomotic leaks, there is no consensus for the role played by each one of them in the healing process of digestive sutures. Most authors sustain that the importance of systemic factors is secondary, the main role being played by the surgeon and the local conditions of the anastomosis. Knowledge of the risk factors can lead to new methods of reducing the incidence of anastomotic leaks by improving vascularization, limiting the tension and the duration of surgery, and by new surgical techniques used for digestive sutures. PMID:26528059

  17. Extinction of in-flight engine fuel-leak fires with dry chemicals

    NASA Technical Reports Server (NTRS)

    Altman, R. L.

    1983-01-01

    The dry chemicals discussed here are seen as having a greater weight effectiveness than the halons in current use for controlling fuel-leak fires, especially in the presence of high airflow rates. The commercial dry chemicals K2CO3, KHCO3, and KC2N2H3O3 are found to be more effective than CF2ClBr and CF3Br in delaying the hot-surface reignition of fuel-leak fires after initial extinguishment. Experimental dry chemical formulations of potassium dawsonite, KAl(OH)2CO3, and of KCl and KI are seen as being even more weight effective than the above-mentioned commercial dry chemicals. It is noted, however, that the suitability and effectiveness of dry chemicals in controlling engine nacele fires has not yet been demonstrated in test aircraft.

  18. Space Shuttle RCS Oxidizer Leak Repair for STS-26

    NASA Technical Reports Server (NTRS)

    Delventhal, R. A.; Faget, N. M.

    1989-01-01

    Following propellant loading of the Space Shuttle's reaction control system (RCS) for mission STS 26, an oxidizer leak was detected in the left orbital maneuvering system (OMS) pod, where the RCS is located. Subsequent investigation determined that the leak was isolated at a mechanical Dynatube fitting near the RCS nitrogen tetroxide tank. An intense effort was initiated to design, fabricate, and qualify a sealing device to stop the oxidizer leak externally so that the Space Shuttle launch could proceed. It was discovered that sealing devices called clamshells were widely used throughout the petrochemical and power generation industries to stop leaks developed in large diameter pipes which carry steam or other hazardous fluids. These clamshells are available in different diameters and strengths and are placed around the pipe at the location of the leak. A sealing compound is then injected under high pressure into the clamshell to stop the leak. This technology was scaled down and applied to the problem of stopping the leak on the Orbiter, which was on a half-inch diameter line in a nearly inaccessible location. Many obstacles had to be overcome such as determining that the sealing material would be compatible with the nitrogen tetroxide and ensuring that the clamshell would actually fit around the Dynatube fitting without interfering with other lines which were in close proximity. The effort at the NASA Johnson Space Center included materials compatibility testing of several sealants, design of a clamshell to fit in the confined compartment, and manufacture and qualification of the flight hardware. A clamshell was successfully placed around the Dynatube fitting on the Orbiter and the oxidizer leak was terminated. Then it was decided to apply this technology further and design clamshells for other mechanical fittings onboard the Orbiter and develop sealing compounds which will be compatible with fuels such as monomethyl hydrazine (MMH). The potential exists for

  19. Identification of sewage leaks by active remote-sensing methods

    NASA Astrophysics Data System (ADS)

    Goldshleger, Naftaly; Basson, Uri

    2016-04-01

    The increasing length of sewage pipelines, and concomitant risk of leaks due to urban and industrial growth and development is exposing the surrounding land to contamination risk and environmental harm. It is therefore important to locate such leaks in a timely manner, to minimize the damage. Advances in active remote sensing Ground Penetrating Radar (GPR) and Frequency Domain Electromagnetic (FDEM) technologies was used to identify leaking potentially responsible for pollution and to identify minor spills before they cause widespread damage. This study focused on the development of these electromagnetic methods to replace conventional acoustic methods for the identification of leaks along sewage pipes. Electromagnetic methods provide an additional advantage in that they allow mapping of the fluid-transport system in the subsurface. Leak-detection systems using GPR and FDEM are not limited to large amounts of water, but enable detecting leaks of tens of liters per hour, because they can locate increases in environmental moisture content of only a few percentage along the pipes. The importance and uniqueness of this research lies in the development of practical tools to provide a snapshot and monitoring of the spatial changes in soil moisture content up to depths of about 3-4 m, in open and paved areas, at relatively low cost, in real time or close to real time. Spatial measurements performed using GPR and FDEM systems allow monitoring many tens of thousands of measurement points per hectare, thus providing a picture of the spatial situation along pipelines and the surrounding. The main purpose of this study was to develop a method for detecting sewage leaks using the above-proposed geophysical methods, since their contaminants can severely affect public health. We focused on identifying, locating and characterizing such leaks in sewage pipes in residential and industrial areas.

  20. Ultrafine cement seals slow leak in casing collar

    SciTech Connect

    Mac Eachern, D. ); Young, S.C. )

    1992-09-07

    This paper reports that an ultrafine cement squeeze effectively sealed a difficult casing collar leak in the protective casing in a deep, high-temperature well in Mobile Bay. The leak was sealed in one operation without perforating the casing, giving greater confidence in casing integrity and allowing the well to be drilled to total depth (TD). Restoring pressure integrity of the casing with this procedure saved approximately $250,000.

  1. Maintenance, Leak Detection in Large Underground Storage Tanks

    DTIC Science & Technology

    2009-05-01

    Responsive! FISC Puget Sound Manchester Fuel Department Maintenance, Leak Detection in Large Underground Storage Tanks Report Documentation Page Form...COVERED 00-00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Maintenance, Leak Detection in Large Underground Storage Tanks 5a. CONTRACT NUMBER 5b...Manchester 13 Regulatory Drivers 40 CFR 280/281 Derives Basic Regulation of Underground Storage Tanks These tanks are Field Constructed – therefore

  2. SSME propellant path leak detection real-time

    NASA Technical Reports Server (NTRS)

    Crawford, R. A.; Smith, L. M.

    1994-01-01

    Included are four documents that outline the technical aspects of the research performed on NASA Grant NAG8-140: 'A System for Sequential Step Detection with Application to Video Image Processing'; 'Leak Detection from the SSME Using Sequential Image Processing'; 'Digital Image Processor Specifications for Real-Time SSME Leak Detection'; and 'A Color Change Detection System for Video Signals with Applications to Spectral Analysis of Rocket Engine Plumes'.

  3. Soil Surface Leak Detection From Carbon Storage Sites Using ∆(CO2:O2) Measurements

    NASA Astrophysics Data System (ADS)

    Alam, M. M.; Norman, A. L.; Layzell, D. B.

    2015-12-01

    The early detection and remediation of CO2 leaks from Carbon Capture and Storage (CCS) sites is essential for the safety and public support of the technology. A model that integrates gas diffusion, mass flow and biological processes in soils was developed and used to predict the ∆CO2 and ∆O2 concentration differential between the soil surface and the bulk atmosphere under a wide range of environmental conditions that include temperature, soil gas and water content, soil respiratory quotient and rate of O2 uptake, soil porosity and CO2 leakage rate. The results predicted that measurement of ∆(CO2:O2) measurements at the soil surface relative to air should be able to detect a CCS leak as low as 2 µmol/m2/sec. To test this hypothesis, a gas analysis system was designed and constructed. It should allow a series of experiments under controlled conditions to test all aspects of the model. It is hoped that the results from this work will ultimately lead to the development of a new instrument and protocol for the early detection of CO2 leaks from a geological storage sites.

  4. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < -1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  5. Local Leak Detection and Health Monitoring of Pressurized Tanks

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt; Witherow, William; Korman, Valentin; Sinko, John; Hendrickson, Adam

    2011-01-01

    An optical gas-detection sensor safely monitors pressurized systems (such as cryogenic tanks) and distribution systems for leaks. This sensor system is a fiber-coupled, solid optical body interferometer that allows for the miniaturized sensing element of the device to be placed in the smallest of recesses, and measures a wide range of gas species and densities (leaks). The deflection of the fringe pattern is detected and recorded to yield the time-varying gas density in the gap. This technology can be used by manufacturers or storage facilities with toxic, hazardous, or explosive gases. The approach is to monitor the change in the index of refraction associated with low-level gas leaks into a vacuum environment. The completion of this work will provide NASA with an enabling capability to detect gas system leaks in space, and to verify that pressurized systems are in a safe (i.e. non-leaking) condition during manned docking and transit operations. By recording the output of the sensor, a time-history of the leak can be constructed to indicate its severity. Project risk is mitigated by having several interferometric geometries and detection techniques available, each potentially leveraging hardware and lessons learned to enhance detectability.

  6. Methane Leaks from Natural Gas Systems Follow Extreme Distributions

    SciTech Connect

    Brandt, Adam R.; Heath, Garvin A.; Cooley, Daniel

    2016-10-14

    Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH4) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ~15,000 measurements from 18 prior studies, we show that all available natural gas leakage datasets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of the total leakage volume. While prior studies used lognormal model distributions, we show that lognormal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of datasets to increase sample size is not recommended due to apparent deviation between sampled populations. Finally, understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.

  7. Reduction of persistent air leak with endoscopic valve implants.

    PubMed

    Toma, Tudor P; Kon, Onn Min; Oldfield, William; Sanefuji, Reina; Griffiths, Mark; Wells, Frank; Sivasothy, Siva; Dusmet, Michael; Geddes, Duncan M; Polkey, Michael I

    2007-09-01

    The standard management of air leaks due to persistent bronchopleural fistula involves chest drainage and occasionally pleurodesis, with intractable cases requiring surgical decortication or surgical repair. However, some of these patients may be at high risk for surgery, particularly if they have already had thoracic surgery or have other medical problems; for this group there is a need for less invasive methods of stopping or reducing air leaks. Emphasys endobronchial valves (EBV) are occlusive devices designed primarily for endoscopic lung volume reduction in emphysema. Because the device is a one-way inspiratory airway blocker, it is possible that it could be used in controlling persistent air leaks while maintaining the drainage of secretions. Two cases are reported of persistent air leaks that were managed by endoscopic occlusion with EBV. In one case complete stoppage of the air leak was achieved with immediate clinical benefits. The second patient died 5 days after treatment from additional complications apparently not related to the procedure. Endobronchial blockage may be a useful salvage procedure for patients with persistent air leak for whom there is no other treatment available.

  8. Leak test fixture and method for using same

    DOEpatents

    Hawk, Lawrence S.

    1976-01-01

    A method and apparatus are provided which are especially useful for leak testing seams such as an end closure or joint in an article. The test does not require an enclosed pressurized volume within the article or joint section to be leak checked. A flexible impervious membrane is disposed over an area of the seamed surfaces to be leak checked and sealed around the outer edges. A preselected vacuum is applied through an opening in the membrane to evacuate the area between the membrane and the surface being leak checked to essentially collapse the membrane to conform to the article surface or joined adjacent surfaces. A pressure differential is concentrated at the seam bounded by the membrane and only the seam experiences a pressure differential as air or helium molecules are drawn into the vacuum system through a leak in the seam. A helium detector may be placed in a vacuum exhaust line from the membrane to detect the helium. Alternatively, the vacuum system may be isolated at a preselected pressure and leaks may be detected by a subsequent pressure increase in the vacuum system.

  9. Methane Leaks from Natural Gas Systems Follow Extreme Distributions

    DOE PAGES

    Brandt, Adam R.; Heath, Garvin A.; Cooley, Daniel

    2016-10-14

    Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH4) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ~15,000 measurements from 18 prior studies, we show that all available natural gas leakage datasets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of the totalmore » leakage volume. While prior studies used lognormal model distributions, we show that lognormal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of datasets to increase sample size is not recommended due to apparent deviation between sampled populations. Finally, understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.« less

  10. Methane Leaks from Natural Gas Systems Follow Extreme Distributions.

    PubMed

    Brandt, Adam R; Heath, Garvin A; Cooley, Daniel

    2016-11-15

    Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH4) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ∼15 000 measurements from 18 prior studies, we show that all available natural gas leakage data sets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of the total leakage volume. While prior studies used log-normal model distributions, we show that log-normal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of data sets to increase sample size is not recommended due to apparent deviation between sampled populations. Understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.

  11. Accurate absolute GPS positioning through satellite clock error estimation

    NASA Astrophysics Data System (ADS)

    Han, S.-C.; Kwon, J. H.; Jekeli, C.

    2001-05-01

    An algorithm for very accurate absolute positioning through Global Positioning System (GPS) satellite clock estimation has been developed. Using International GPS Service (IGS) precise orbits and measurements, GPS clock errors were estimated at 30-s intervals. Compared to values determined by the Jet Propulsion Laboratory, the agreement was at the level of about 0.1 ns (3 cm). The clock error estimates were then applied to an absolute positioning algorithm in both static and kinematic modes. For the static case, an IGS station was selected and the coordinates were estimated every 30 s. The estimated absolute position coordinates and the known values had a mean difference of up to 18 cm with standard deviation less than 2 cm. For the kinematic case, data obtained every second from a GPS buoy were tested and the result from the absolute positioning was compared to a differential GPS (DGPS) solution. The mean differences between the coordinates estimated by the two methods are less than 40 cm and the standard deviations are less than 25 cm. It was verified that this poorer standard deviation on 1-s position results is due to the clock error interpolation from 30-s estimates with Selective Availability (SA). After SA was turned off, higher-rate clock error estimates (such as 1 s) could be obtained by a simple interpolation with negligible corruption. Therefore, the proposed absolute positioning technique can be used to within a few centimeters' precision at any rate by estimating 30-s satellite clock errors and interpolating them.

  12. Postoperative Low-Flow Cerebrospinal Fluid Leak of Endoscopic Endonasal Transsphenoidal Surgery for Pituitary Adenoma--Wait and See, or Lumbar Drain?

    PubMed

    Zhan, Rucai; Chen, Songyu; Xu, Shujun; Liu, James K; Li, Xingang

    2015-06-01

    To assess the effectiveness of continuous lumbar drainage (LD) for management of postoperative cerebrospinal fluid leaks after endoscopic endonasal transsphenoidal approach for resection of pituitary adenoma. Three hundred eighty-four medical records of patients who were admitted to our institute during a 2.5-year period were retrospectively reviewed, 33 of them experienced low-flow cerebrospinal fluid leak postoperatively. If LD was used, all patients with low-flow cerebrospinal fluid leak were classified into 2 groups, lumbar drained group and conservatively treated group. The age, sex, management of cerebrospinal fluid leaks, and related complications were reviewed. Statistical comparisons between the 2 groups were made using SPSS 19.0 (IBM Corp, Armonk, NY). The differences were considered statistically significant if the P value was less than 0.05.Thirty-three of 384 (8.6%) experienced low-flow postoperative cerebrospinal fluid leaks. Cured rate of cerebrospinal fluid leak was 94.4% (17/18) in continuous lumbar drained group, and 93.3% (14/15) in control group. There were 2 (11.2%) patients who developed meningitis in the LD group and 1 (5.6%) patient in the control group. One patient required endoscopic repair of skull base because of persistent cerebrospinal fluid leak in both groups, with the rates of 5.6% and 6.7%, respectively. There was no significant difference noted in each rate in both groups.Placement of LD may not be necessary for the management of low-flow postoperative cerebrospinal fluid leak after using endoscopic endonasal transsphenoidal approach to pituitary adenoma.

  13. Fugitive methane emissions from leak-prone natural gas distribution infrastructure in urban environments.

    PubMed

    Hendrick, Margaret F; Ackley, Robert; Sanaie-Movahed, Bahare; Tang, Xiaojing; Phillips, Nathan G

    2016-06-01

    Fugitive emissions from natural gas systems are the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. and contribute to the risk of explosions in urban environments. Here, we report on a survey of CH4 emissions from 100 natural gas leaks in cast iron distribution mains in Metro Boston, MA. Direct measures of CH4 flux from individual leaks ranged from 4.0 - 2.3 × 10(4) g CH4•day(-1). The distribution of leak size is positively skewed, with 7% of leaks contributing 50% of total CH4 emissions measured. We identify parallels in the skewed distribution of leak size found in downstream systems with midstream and upstream stages of the gas process chain. Fixing 'superemitter' leaks will disproportionately stem greenhouse gas emissions. Fifteen percent of leaks surveyed qualified as potentially explosive (Grade 1), and we found no difference in CH4 flux between Grade 1 leaks and all remaining leaks surveyed (p = 0.24). All leaks must be addressed, as even small leaks cannot be disregarded as 'safely leaking.' Key methodological impediments to quantifying and addressing the impacts of leaking natural gas distribution infrastructure involve inconsistencies in the manner in which gas leaks are defined, detected, and classified. To address this need, we propose a two-part leak classification system that reflects both the safety and climatic impacts of natural gas leaks.

  14. Absolute photon-flux measurements in the vacuum ultraviolet

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Haddad, G. N.

    1974-01-01

    Absolute photon-flux measurements in the vacuum ultraviolet have extended to short wavelengths by use of rare-gas ionization chambers. The technique involves the measurement of the ion current as a function of the gas pressure in the ion chamber. The true value of the ion current, and hence the absolute photon flux, is obtained by extrapolating the ion current to zero gas pressure. Examples are given at 162 and 266 A. The short-wavelength limit is determined only by the sensitivity of the current-measuring apparatus and by present knowledge of the photoionization processes that occur in the rate gases.

  15. Absolute GPS Positioning Using Genetic Algorithms

    NASA Astrophysics Data System (ADS)

    Ramillien, G.

    A new inverse approach for restoring the absolute coordinates of a ground -based station from three or four observed GPS pseudo-ranges is proposed. This stochastic method is based on simulations of natural evolution named genetic algorithms (GA). These iterative procedures provide fairly good and robust estimates of the absolute positions in the Earth's geocentric reference system. For comparison/validation, GA results are compared to the ones obtained using the classical linearized least-square scheme for the determination of the XYZ location proposed by Bancroft (1985) which is strongly limited by the number of available observations (i.e. here, the number of input pseudo-ranges must be four). The r.m.s. accuracy of the non -linear cost function reached by this latter method is typically ~10-4 m2 corresponding to ~300-500-m accuracies for each geocentric coordinate. However, GA can provide more acceptable solutions (r.m.s. errors < 10-5 m2), even when only three instantaneous pseudo-ranges are used, such as a lost of lock during a GPS survey. Tuned GA parameters used in different simulations are N=1000 starting individuals, as well as Pc=60-70% and Pm=30-40% for the crossover probability and mutation rate, respectively. Statistical tests on the ability of GA to recover acceptable coordinates in presence of important levels of noise are made simulating nearly 3000 random samples of erroneous pseudo-ranges. Here, two main sources of measurement errors are considered in the inversion: (1) typical satellite-clock errors and/or 300-metre variance atmospheric delays, and (2) Geometrical Dilution of Precision (GDOP) due to the particular GPS satellite configuration at the time of acquisition. Extracting valuable information and even from low-quality starting range observations, GA offer an interesting alternative for high -precision GPS positioning.

  16. Detecting leaks in hydrocarbon storage tanks using electrical resistance tomography

    SciTech Connect

    Daily, W.; Ramirez, A.; LaBrecque, D.; Binley, A.

    1995-04-03

    Large volumes of hydrocarbons are stored worldwide in surface and underground tanks. It is well documented [1] that all too often these tanks are found to leak, resulting in not only a loss of stored inventory but, more importantly, contamination to soil and groundwater. Two field experiments are reported herein to evaluate the utility of electrical resistance tomography (ERT) for detecting and locating leaks as well as delineating any resulting plumes emanating from steel underground storage tanks (UST). Current leak detection methods for single shell tanks require careful inventory monitoring, usually from liquid level sensors within the tank, or placement of chemical sensors in the soil under and around the tank. Liquid level sensors can signal a leak but are limited in sensitivity and, of course, give no information about the location or the leak or the distribution of the resulting plume. External sensors are expensive to retrofit and must be very densely spaced to assure reliable detection, especially in heterogeneous soils. The rational for using subsurface tomography is that it may have none of these shortcomings.

  17. Implementation of Leak Test Methods for the International Space Station (ISS) Elements, Systems and Components

    NASA Technical Reports Server (NTRS)

    Underwood, Steve; Lvovsky, Oleg

    2007-01-01

    The International Space Station (ISS has Qualification and Acceptance Environmental Test Requirements document, SSP 41172 that includes many environmental tests such as Thermal vacuum & Cycling, Depress/Repress, Sinusoidal, Random, and Acoustic Vibration, Pyro Shock, Acceleration, Humidity, Pressure, Electromatic Interference (EMI)/Electromagnetic Compatibility (EMCO), etc. This document also includes (13) leak test methods for Pressure Integrity Verification of the ISS Elements, Systems, and Components. These leak test methods are well known, however, the test procedure for specific leak test method shall be written and implemented paying attention to the important procedural steps/details that, if omitted or deviated, could impact the quality of the final product and affect the crew safety. Such procedural steps/details for different methods include, but not limited to: - Sequence of testing, f or example, pressurization and submersion steps for Method I (Immersion); - Stabilization of the mass spectrometer leak detector outputs fo r Method II (vacuum Chamber or Bell jar); - Proper data processing an d taking a conservative approach while making predictions for on-orbit leakage rate for Method III(Pressure Change); - Proper Calibration o f the mass spectrometer leak detector for all the tracer gas (mostly Helium) Methods such as Method V (Detector Probe), Method VI (Hood), Method VII (Tracer Probe), Method VIII(Accumulation); - Usage of visibl ility aides for Method I (Immersion), Method IV (Chemical Indicator), Method XII (Foam/Liquid Application), and Method XIII (Hydrostatic/Visual Inspection); While some methods could be used for the total leaka ge (either internal-to-external or external-to-internal) rate requirement verification (Vacuum Chamber, Pressure Decay, Hood, Accumulation), other methods shall be used only as a pass/fail test for individual joints (e.g., welds, fittings, and plugs) or for troubleshooting purposes (Chemical Indicator, Detector Probe

  18. Integral Aircraft Fuel Tank Leak Classification

    DTIC Science & Technology

    1980-01-01

    effects of the following parameters on the rate of surface dispersion of fuels were examined: fuel type, leakage rate, surface material, fuel and...ranging from 3.34C to 98 C (38OF to 209’F). The vapor pressure of the fuel at the test temperature has a very pronounced effect on the propensity of the...Fuels and the Effect of Flow Rate 8 Effect of Temperature 14 Effect of Air Flow Rate 14 Effect of Panel Angle of Inclination 19 Effect of Panel

  19. What is Needed for Absolute Paleointensity?

    NASA Astrophysics Data System (ADS)

    Valet, J. P.

    2015-12-01

    Many alternative approaches to the Thellier and Thellier technique for absolute paleointensity have been proposed during the past twenty years. One reason is the time consuming aspect of the experiments. Another reason is to avoid uncertainties in determinations of the paleofield which are mostly linked to the presence of multidomain grains. Despite great care taken by these new techniques, there is no indication that they always provide the right answer and in fact sometimes fail. We are convinced that the most valid approach remains the original double heating Thellier protocol provided that natural remanence is controlled by pure magnetite with a narrow distribution of small grain sizes, mostly single domains. The presence of titanium, even in small amount generates biases which yield incorrect field values. Single domain grains frequently dominate the magnetization of glass samples, which explains the success of this selective approach. They are also present in volcanic lava flows but much less frequently, and therefore contribute to the low success rate of most experiments. However the loss of at least 70% of the magnetization at very high temperatures prior to the Curie point appears to be an essential prerequisite that increases the success rate to almost 100% and has been validated from historical flows and from recent studies. This requirement can easily be tested by thermal demagnetization while low temperature experiments can document the detection of single domain magnetite using the δFC/δZFC parameter as suggested (Moskowitz et al, 1993) for biogenic magnetite.

  20. Hermetic Seal Leak Detection Apparatus with Variable Size Test Chamber

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R. (Inventor)

    2015-01-01

    The present invention is a versatile hermetic seal leak detection apparatus for testing hermetically sealed containers and devices for leaks without the need to create a custom or specially manufactured testing chamber conforming to the dimensions of the specific object under test. The size of the testing chamber may be mechanically adjusted by the novel use of bellows to reduce and optimize the amount of gas space in a test chamber which surrounds the hermetically sealed object under test. The present invention allows the size of the test chamber to be selectively adjusted during testing to provide an optimum test chamber gas space. The present invention may be further adapted to isolate and test specific portions of the hermetically sealed object under test for leaks.

  1. Gas-leak localization using distributed ultrasonic sensors

    NASA Astrophysics Data System (ADS)

    Huseynov, Javid; Baliga, Shankar; Dillencourt, Michael; Bic, Lubomir; Bagherzadeh, Nader

    2009-03-01

    We propose an ultrasonic gas leak localization system based on a distributed network of sensors. The system deploys highly sensitive miniature Micro-Electro-Mechanical Systems (MEMS) microphones and uses a suite of energy-decay (ED) and time-delay of arrival (TDOA) algorithms for localizing a source of a gas leak. Statistical tools such as the maximum likelihood (ML) and the least squares (LS) estimators are used for approximating the source location when closed-form solutions fail in the presence of ambient background nuisance and inherent electronic noise. The proposed localization algorithms were implemented and tested using a Java-based simulation platform connected to four or more distributed MEMS microphones observing a broadband nitrogen leak from an orifice. The performance of centralized and decentralized algorithms under ED and TDOA schemes is analyzed and compared in terms of communication overhead and accuracy in presence of additive white Gaussian noise (AWGN).

  2. Apparatus and method for detecting leaks in piping

    DOEpatents

    Trapp, D.J.

    1994-12-27

    A method and device are disclosed for detecting the location of leaks along a wall or piping system, preferably in double-walled piping. The apparatus comprises a sniffer probe, a rigid cord such as a length of tube attached to the probe on one end and extending out of the piping with the other end, a source of pressurized air and a source of helium. The method comprises guiding the sniffer probe into the inner pipe to its distal end, purging the inner pipe with pressurized air, filling the annulus defined between the inner and outer pipe with helium, and then detecting the presence of helium within the inner pipe with the probe as is pulled back through the inner pipe. The length of the tube at the point where a leak is detected determines the location of the leak in the pipe. 2 figures.

  3. Apparatus and method for detecting leaks in piping

    DOEpatents

    Trapp, Donald J.

    1994-01-01

    A method and device for detecting the location of leaks along a wall or piping system, preferably in double-walled piping. The apparatus comprises a sniffer probe, a rigid cord such as a length of tube attached to the probe on one end and extending out of the piping with the other end, a source of pressurized air and a source of helium. The method comprises guiding the sniffer probe into the inner pipe to its distal end, purging the inner pipe with pressurized air, filling the annulus defined between the inner and outer pipe with helium, and then detecting the presence of helium within the inner pipe with the probe as is pulled back through the inner pipe. The length of the tube at the point where a leak is detected determines the location of the leak in the pipe.

  4. Oil/gas collector/separator for underwater oil leaks

    SciTech Connect

    Henning, C.D.

    1992-12-31

    This invention is comprised of an oil/gas collector/separator for recovery of oil leaking, for example, from an offshore or underwater oil well. The separator is floated over the point of the leak and tethered in place so as to receive oil/gas floating, or forced under pressure, toward the water surface from either a broken or leaking oil well casing, line, or sunken ship. The separator is provided with a downwardly extending skirt to contain the oil/gas which floats or is forced upward into a dome wherein the gas is separated from the oil/water, with the gas being flared (burned) at the top of the dome, and the oil is separated from water and pumped to a point of use. Since the density of oil is less than that of water it can be easily separated from any water entering the dome.

  5. Echocardiographic findings in patients with spontaneous CSF leak.

    PubMed

    Pimienta, Allen L; Rimoin, David L; Pariani, Mitchel; Schievink, Wouter I; Reinstein, Eyal

    2014-10-01

    The presence of cardiovascular abnormalities in patients with spontaneous cerebrospinal fluid (CSF) leaks are not well-documented in the literature, as cardiovascular evaluation is not generally pursued if a patient does not exhibit additional clinical features suggesting an inherited connective tissue disorder. We aimed to assess this association, enrolling a consecutive group of 50 patients referred for spinal CSF leak consultation. Through echocardiographic evaluation and detailed medical history, we estimate that up to 20% of patients presenting with a spontaneous CSF leak may have some type of cardiovascular abnormality. Further, the increase in prevalence of aortic dilatation in our cohort was statistically significant in comparison to the estimated population prevalence. This supports a clinical basis for echocardiographic screening of these individuals for cardiovascular manifestations that may have otherwise gone unnoticed or evolved into a more severe manifestation.

  6. Oil/gas collector/separator for underwater oil leaks

    DOEpatents

    Henning, Carl D.

    1993-01-01

    An oil/gas collector/separator for recovery of oil leaking, for example, from an offshore or underwater oil well. The separator is floated over the point of the leak and tethered in place so as to receive oil/gas floating, or forced under pressure, toward the water surface from either a broken or leaking oil well casing, line, or sunken ship. The separator is provided with a downwardly extending skirt to contain the oil/gas which floats or is forced upward into a dome wherein the gas is separated from the oil/water, with the gas being flared (burned) at the top of the dome, and the oil is separated from water and pumped to a point of use. Since the density of oil is less than that of water it can be easily separated from any water entering the dome.

  7. High Altitude Aerial Natural Gas Leak Detection System

    SciTech Connect

    Richard T. Wainner; Mickey B. Frish; B. David Green; Matthew C. Laderer; Mark G. Allen; Joseph R. Morency

    2006-12-31

    The objective of this program was to develop and demonstrate a cost-effective and power-efficient advanced standoff sensing technology able to detect and quantify, from a high-altitude (> 10,000 ft) aircraft, natural gas leaking from a high-pressure pipeline. The advanced technology is based on an enhanced version of the Remote Methane Leak Detector (RMLD) platform developed previously by Physical Sciences Inc. (PSI). The RMLD combines a telecommunications-style diode laser, fiber-optic components, and low-cost DSP electronics with the well-understood principles of Wavelength Modulation Spectroscopy (WMS), to indicate the presence of natural gas located between the operator and a topographic target. The transceiver transmits a laser beam onto a topographic target and receives some of the laser light reflected by the target. The controller processes the received light signal to deduce the amount of methane in the laser's path. For use in the airborne platform, we modified three aspects of the RMLD, by: (1) inserting an Erbium-doped optical fiber laser amplifier to increase the transmitted laser power from 10 mW to 5W; (2) increasing the optical receiver diameter from 10 cm to 25 cm; and (3) altering the laser wavelength from 1653 nm to 1618 nm. The modified RMLD system provides a path-integrated methane concentration sensitivity {approx}5000 ppm-m, sufficient to detect the presence of a leak from a high capacity transmission line while discriminating against attenuation by ambient methane. In ground-based simulations of the aerial leak detection scenario, we demonstrated the ability to measure methane leaks within the laser beam path when it illuminates a topographic target 2000 m away. We also demonstrated simulated leak detection from ranges of 200 m using the 25 cm optical receiver without the fiber amplifier.

  8. Absolute optical metrology : nanometers to kilometers

    NASA Technical Reports Server (NTRS)

    Dubovitsky, Serge; Lay, O. P.; Peters, R. D.; Liebe, C. C.

    2005-01-01

    We provide and overview of the developments in the field of high-accuracy absolute optical metrology with emphasis on space-based applications. Specific work on the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor is described along with novel applications of the sensor.

  9. ON A SUFFICIENT CONDITION FOR ABSOLUTE CONTINUITY.

    DTIC Science & Technology

    The formulation of a condition which yields absolute continuity when combined with continuity and bounded variation is the problem considered in the...Briefly, the formulation is achieved through a discussion which develops a proof by contradiction of a sufficiently theorem for absolute continuity which uses in its hypothesis the condition of continuity and bounded variation .

  10. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  11. Monolithically integrated absolute frequency comb laser system

    SciTech Connect

    Wanke, Michael C.

    2016-07-12

    Rather than down-convert optical frequencies, a QCL laser system directly generates a THz frequency comb in a compact monolithically integrated chip that can be locked to an absolute frequency without the need of a frequency-comb synthesizer. The monolithic, absolute frequency comb can provide a THz frequency reference and tool for high-resolution broad band spectroscopy.

  12. Overspecification of color, pattern, and size: salience, absoluteness, and consistency

    PubMed Central

    Tarenskeen, Sammie; Broersma, Mirjam; Geurts, Bart

    2015-01-01

    The rates of overspecification of color, pattern, and size are compared, to investigate how salience and absoluteness contribute to the production of overspecification. Color and pattern are absolute and salient attributes, whereas size is relative and less salient. Additionally, a tendency toward consistent responses is assessed. Using a within-participants design, we find similar rates of color and pattern overspecification, which are both higher than the rate of size overspecification. Using a between-participants design, however, we find similar rates of pattern and size overspecification, which are both lower than the rate of color overspecification. This indicates that although many speakers are more likely to include color than pattern (probably because color is more salient), they may also treat pattern like color due to a tendency toward consistency. We find no increase in size overspecification when the salience of size is increased, suggesting that speakers are more likely to include absolute than relative attributes. However, we do find an increase in size overspecification when mentioning the attributes is triggered, which again shows that speakers tend to refer in a consistent manner, and that there are circumstances in which even size overspecification is frequently produced. PMID:26594190

  13. Secondary containment and leak detection: A great marriage

    SciTech Connect

    Geyer, W.B.; Stellmach, W.A.

    1995-04-01

    The past decade has seen a proliferation of sophisticated release detection systems for both underground and aboveground storage tanks. But leak detection alone will not ensure against contamination. The storage tank owner who has to spend $100,000 or more to clean up contaminated soil - and much more if groundwater becomes tainted - could have avoided real headaches by investing in sound secondary containment in addition to leak detection. Combined with release detection devices, secondary containment provides the best insurance for UST owners through containment of the primary tank and its piping. We call this a great marriage between two technologies - and EPA agrees.

  14. Wide-band gas leak imaging detection system using UFPA

    NASA Astrophysics Data System (ADS)

    Jin, Wei-qi; Li, Jia-kun; Dun, Xiong; Jin, Minglei; Wang, Xia

    2014-11-01

    The leakage of toxic or hazardous gases not only pollutes the environment, but also threatens people's lives and property safety. Many countries attach great importance to the rapid and effective gas leak detection technology and instrument development. However, the gas leak imaging detection systems currently existing are generally limited to a narrow-band in Medium Wavelength Infrared (MWIR) or Long Wavelength Infrared (LWIR) cooled focal plane imaging, which is difficult to detect the common kinds of the leaking gases. Besides the costly cooled focal plane array is utilized, the application promotion is severely limited. To address this issue, a wide-band gas leak IR imaging detection system using Uncooled Focal Plane Array (UFPA) detector is proposed, which is composed of wide-band IR optical lens, sub-band filters and switching device, wide-band UFPA detector, video processing and system control circuit. A wide-band (3µm~12µm) UFPA detector is obtained by replacing the protection window and optimizing the structural parameters of the detector. A large relative aperture (F#=0.75) wide-band (3μm~12μm) multispectral IR lens is developed by using the focus compensation method, which combining the thickness of the narrow-band filters. The gas leak IR image quality and the detection sensitivity are improved by using the IR image Non-Uniformity Correction (NUC) technology and Digital Detail Enhancement (DDE) technology. The wide-band gas leak IR imaging detection system using UFPA detector takes full advantage of the wide-band (MWIR&LWIR) response characteristic of the UFPA detector and the digital image processing technology to provide the resulting gas leak video easy to be observed for the human eyes. Many kinds of gases, which are not visible to the naked eyes, can be sensitively detected and visualized. The designed system has many commendable advantages, such as scanning a wide range simultaneously, locating the leaking source quickly, visualizing the gas

  15. Leak before break application in French PWR plants under operation

    SciTech Connect

    Faidy, C.

    1997-04-01

    Practical applications of the leak-before break concept are presently limited in French Pressurized Water Reactors (PWR) compared to Fast Breeder Reactors. Neithertheless, different fracture mechanic demonstrations have been done on different primary, auxiliary and secondary PWR piping systems based on similar requirements that the American NUREG 1061 specifications. The consequences of the success in different demonstrations are still in discussion to be included in the global safety assessment of the plants, such as the consequences on in-service inspections, leak detection systems, support optimization,.... A large research and development program, realized in different co-operative agreements, completes the general approach.

  16. [Leak of anesthetic gases inside the anesthesia machine].

    PubMed

    Tanaka, Tadashi; Masaki, Go; Kato, Hidetaka; Takita, Eiichi; Sugai, Naosuke

    2006-05-01

    We experienced the leak of anesthetic gases inside the anesthesia machine in spite of performing the leak test before its use. After induction of anesthesia, a laryngeal mask airway was inserted and the patient was ventilated manually. At the beginning we could not find any signs of machine troubles. High airway pressure occurred immediately after switching to the mechanical ventilation. Because we could not detect the details of the machine trouble, tidal volume was set lower and the surgery was continued. After surgery, we found a crack in a fresh gas circuit valve. We have to check the anesthesia machine regularly and know its duration of use.

  17. Approach to evaluating leak detection methods in underground storage tanks

    NASA Astrophysics Data System (ADS)

    Starr, J.; Broscious, J.; Niaki, S.

    1986-10-01

    The detection and evaluation of leaks in underground storage tanks require a detailed knowledge of conditions both within the tank and in the nearby surroundings. The test apparatus, as constructed, enables data regarding these environmental conditions to be readily obtained and incorporated in a carefully structured test program that minimizes the amount of costly full-scale testing that would otherwise be required to evaluate volumetric leak detection methods for underground storage tanks. In addition, sufficient flexibility has been designed into the apparatus to enable additional evaluations of non-volumetric test methods to be conducted, and different types of tanks and products to be tested in a cost-effective manner.

  18. Minimally invasive management of anastomotic leaks in colorectal surgery

    PubMed Central

    Sevim, Yusuf; Celik, Suleyman Utku; Yavarifar, Hana; Akyol, Cihangir

    2016-01-01

    Anastomotic leakage is an unfortunate complication of colorectal surgery. This distressing situation can cause severe morbidity and significantly affects the patient’s quality of life. Additional interventions may cause further morbidity and mortality. Parenteral nutrition and temporary diverting ostomy are the standard treatments of anastomotic leaks. However, technological developments in minimally invasive treatment modalities for anastomotic dehiscence have caused them to be used widely. These modalities include laparoscopic repair, endoscopic self-expandable metallic stents, endoscopic clips, over the scope clips, endoanal repair and endoanal sponges. The review aimed to provide an overview of the current knowledge on the minimally invasive management of anastomotic leaks. PMID:27721925

  19. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  20. Leak detection by acoustic emissions monitoring: An experimental investigation of the acoustic properties of leaks and the attenuation characteristics of soil

    NASA Astrophysics Data System (ADS)

    Kilpatrick, James F.; March, Patrick A.

    1994-05-01

    This study experimentally explored the conditions, equipment, and methodology necessary for the acoustic detection of small leaks of jet fuel (JP4) from underground storage tank (UST) systems. The study indicates that acoustic leak detection of very small leaks is feasible. In general, significant JP4 fuel leaks which occur across a 5 PSI (pounds per square inch) or greater pressure drop are acoustically active and can be detected with proper sensors and proper placement of sensors. The primary source of leak noise is turbulent flow through the leak orifice. At lower pressures, the leak flow becomes laminar, and the leak becomes virtually silent. With direct transducer contact on the pipe or tank wall and sufficient system pressure, leaks smaller than 0.1 GPH (gallons per hour) can be detected. Larger leaks can be detected through short distances in soil. However, sand, which is the most commonly used fill material for UST systems, provides significant acoustic attenuation. Consequently, waveguides must be used when monitoring distances exceeding about 1 foot of travel through sand. Sand acts to reduce background noise levels, providing an ideal environment for acoustic leak detection using sensors mounted directly on the pipe or tank wall.

  1. Implications and Cost of Pancreatic Leak Following Distal Pancreatic Resection

    PubMed Central

    Rodríguez, J. Rubén; Germes, Santos Soto; Pandharipande, Pari V.; Gazelle, G. Scott; Thayer, Sarah P.; Warshaw, Andrew L.; Fernández-del Castillo, Carlos

    2014-01-01

    Objectives Pancreatic stump leak (PL) after elective distal pancreatic resection significantly impacts cost and increases subsequent health care resource utilization. We sought to provide an economic framework for potential interventions aimed at reducing its occurrence. Design Retrospective case series and economic evaluation. Setting University-affiliated, tertiary care referral center. Patients Sixty-six patients undergoing elective distal, pancreatectomy. Main Outcome Measures Postoperative complications; hospital and professional costs. Results Overall postoperative morbidity occurred in 34 patients (52%) with no deaths. The total number of patients with complications directly related to PL was 22 (33%). The mean ± SD number of total hospital days for the no-PL group was 5.2 ± 1.7 days (range, 3–12 days) vs 16.6 ± 14.6 days (range, 4–49 days) for the PL group (P = .001). The average patient with PL-related problems incurred a total cost that was 2.01 times greater than the average patient in the no-PL group. A decision analytic model developed to evaluate threshold costs showed that a hypothetical intervention designed to reduce the complication rate of distal pancreatectomy by one third would be financially justifiable up to a cost of $1418 per patient. Conclusions Complications derived from PL following distal pancreatectomy double the cost and dramatically increase health care resource utilization. There is an urgent need to develop strategies that reduce the incidence of this common complication. Interventions aimed at decreasing the incidence of PL should take into account this cost differential. We provide an economic model to serve as a guide for developing these technologies. PMID:16618893

  2. Orion Absolute Navigation System Progress and Challenge

    NASA Technical Reports Server (NTRS)

    Holt, Greg N.; D'Souza, Christopher

    2012-01-01

    The absolute navigation design of NASA's Orion vehicle is described. It has undergone several iterations and modifications since its inception, and continues as a work-in-progress. This paper seeks to benchmark the current state of the design and some of the rationale and analysis behind it. There are specific challenges to address when preparing a timely and effective design for the Exploration Flight Test (EFT-1), while still looking ahead and providing software extensibility for future exploration missions. The primary onboard measurements in a Near-Earth or Mid-Earth environment consist of GPS pseudo-range and delta-range, but for future explorations missions the use of star-tracker and optical navigation sources need to be considered. Discussions are presented for state size and composition, processing techniques, and consider states. A presentation is given for the processing technique using the computationally stable and robust UDU formulation with an Agee-Turner Rank-One update. This allows for computational savings when dealing with many parameters which are modeled as slowly varying Gauss-Markov processes. Preliminary analysis shows up to a 50% reduction in computation versus a more traditional formulation. Several state elements are discussed and evaluated, including position, velocity, attitude, clock bias/drift, and GPS measurement biases in addition to bias, scale factor, misalignment, and non-orthogonalities of the accelerometers and gyroscopes. Another consideration is the initialization of the EKF in various scenarios. Scenarios such as single-event upset, ground command, and cold start are discussed as are strategies for whole and partial state updates as well as covariance considerations. Strategies are given for dealing with latent measurements and high-rate propagation using multi-rate architecture. The details of the rate groups and the data ow between the elements is discussed and evaluated.

  3. Absolute quantitation of protein posttranslational modification isoform.

    PubMed

    Yang, Zhu; Li, Ning

    2015-01-01

    Mass spectrometry has been widely applied in characterization and quantification of proteins from complex biological samples. Because the numbers of absolute amounts of proteins are needed in construction of mathematical models for molecular systems of various biological phenotypes and phenomena, a number of quantitative proteomic methods have been adopted to measure absolute quantities of proteins using mass spectrometry. The liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with internal peptide standards, i.e., the stable isotope-coded peptide dilution series, which was originated from the field of analytical chemistry, becomes a widely applied method in absolute quantitative proteomics research. This approach provides more and more absolute protein quantitation results of high confidence. As quantitative study of posttranslational modification (PTM) that modulates the biological activity of proteins is crucial for biological science and each isoform may contribute a unique biological function, degradation, and/or subcellular location, the absolute quantitation of protein PTM isoforms has become more relevant to its biological significance. In order to obtain the absolute cellular amount of a PTM isoform of a protein accurately, impacts of protein fractionation, protein enrichment, and proteolytic digestion yield should be taken into consideration and those effects before differentially stable isotope-coded PTM peptide standards are spiked into sample peptides have to be corrected. Assisted with stable isotope-labeled peptide standards, the absolute quantitation of isoforms of posttranslationally modified protein (AQUIP) method takes all these factors into account and determines the absolute amount of a protein PTM isoform from the absolute amount of the protein of interest and the PTM occupancy at the site of the protein. The absolute amount of the protein of interest is inferred by quantifying both the absolute amounts of a few PTM

  4. The application of capnography to differentiate peri-chest tube air leak from parenchymal leak following pulmonary surgery

    PubMed Central

    Walker, William S.

    2014-01-01

    Prolonged air leak is a common complication of pulmonary resection. However, while a bubbling chest drain is commonly related to parenchymal air leakage, it may also be caused by air entering the pleural cavity via an incomplete seal of the tissues at the chest tube insertion site. Examination alone is not sufficient to guide the surgeon as to which of the above complications is responsible for drain bubbling. We describe a simple method, whereby a CO2 monitoring device is attached to the chest drain to determine whether the air loss observed is in fact due to a pulmonary air leak. PMID:24790853

  5. Absolute realization of low BRDF value

    NASA Astrophysics Data System (ADS)

    Liu, Zilong; Liao, Ningfang; Li, Ping; Wang, Yu

    2010-10-01

    Low BRDF value is widespread used in many critical domains such as space and military fairs. These values below 0.1 Sr-1 . So the Absolute realization of these value is the most critical issue in the absolute measurement of BRDF. To develop the Absolute value realization theory of BRDF , defining an arithmetic operators of BRDF , achieving an absolute measurement Eq. of BRDF based on radiance. This is a new theory method to solve the realization problem of low BRDF value. This theory method is realized on a self-designed common double orientation structure in space. By designing an adding structure to extend the range of the measurement system and a control and processing software, Absolute realization of low BRDF value is achieved. A material of low BRDF value is measured in this measurement system and the spectral BRDF value are showed within different angles allover the space. All these values are below 0.4 Sr-1 . This process is a representative procedure about the measurement of low BRDF value. A corresponding uncertainty analysis of this measurement data is given depend on the new theory of absolute realization and the performance of the measurement system. The relative expand uncertainty of the measurement data is 0.078. This uncertainty analysis is suitable for all measurements using the new theory of absolute realization and the corresponding measurement system.

  6. The EM-POGO: A simple, absolute velocity profiler

    NASA Astrophysics Data System (ADS)

    Terker, S. R.; Sanford, T. B.; Dunlap, J. H.; Girton, J. B.

    2013-01-01

    Electromagnetic current instrumentation has been added to the Bathy Systems, Inc. POGO transport sondes to produce a free-falling absolute velocity profiler called EM-POGO. The POGO is a free-fall profiler that measures a depth-averaged velocity using GPS fixes at the beginning and end of a round trip to the ocean floor (or a preset depth). The EM-POGO adds a velocity profile determined from measurements of motionally induced electric fields generated by the ocean current moving through the vertical component of the Earth's magnetic field. In addition to providing information about the vertical structure of the velocity, the depth-dependent measurements improve transport measurements by correcting for the non-constant fall-rate. Neglecting the variable fall rate results in errors O (1 cm s-1). The transition from POGO to EM-POGO included electrically isolating the POGO and electric-field-measuring circuits, installing a functional GPS receiver, finding a pressure case that provided an optimal balance among crush-depth, price and size, and incorporating the electrodes, electrode collar, and the circuitry required for the electric field measurement. The first EM-POGO sea-trial was in July 1999. In August 2006 a refurbished EM-POGO collected 15 absolute velocity profiles; relative and absolute velocity uncertainty was ˜1cms-1 and 0.5-5 cm s-1, respectively, at a vertical resolution of 25 m. Absolute velocity from the EM-POGO compared to shipboard ADCP measurements differed by ˜ 1-2 cm s-1, comparable to the uncertainty in absolute velocity from the ADCP. The EM-POGO is thus a low-cost, easy to deploy and recover, and accurate velocity profiler.

  7. 40 CFR 63.1255 - Standards: Equipment leaks.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 12 2014-07-01 2014-07-01 false Standards: Equipment leaks. 63.1255 Section 63.1255 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES...

  8. 40 CFR 63.1363 - Standards for equipment leaks.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 12 2014-07-01 2014-07-01 false Standards for equipment leaks. 63.1363 Section 63.1363 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES...

  9. 10 CFR 36.59 - Detection of leaking sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of...

  10. 40 CFR 63.1331 - Equipment leak provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... in pumps and agitator seals in light liquid service shall not be considered to be a leak. For... polymer fluid used to provide lubrication and/or cooling of the pump or agitator shaft exits the pump... by § 63.1335(e)(6). (6) For pumps, valves, connectors, and agitators in heavy liquid...

  11. 40 CFR 63.1331 - Equipment leak provisions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... in pumps and agitator seals in light liquid service shall not be considered to be a leak. For... polymer fluid used to provide lubrication and/or cooling of the pump or agitator shaft exits the pump... by § 63.1335(e)(6). (6) For pumps, valves, connectors, and agitators in heavy liquid...

  12. 40 CFR 63.1331 - Equipment leak provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... in pumps and agitator seals in light liquid service shall not be considered to be a leak. For... polymer fluid used to provide lubrication and/or cooling of the pump or agitator shaft exits the pump... by § 63.1335(e)(6). (6) For pumps, valves, connectors, and agitators in heavy liquid...

  13. Thermal-leak analyzer for vacuum-jacketed lines

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Iceland, W. F.; Ruppe, E. P.

    1978-01-01

    Technique involves coating suspected area with water-soluble black paint that gives even, infrared emission. Painted area is warmed with heat gun; an infrared scanner is used to detect cooled spot on jacket exterior. Introduction of atmospheric pressure into jacket intensifies leak jet and improves test sensitivity.

  14. Acoustic leak-detection system for railroad transportation security

    NASA Astrophysics Data System (ADS)

    Womble, P. C.; Spadaro, J.; Harrison, M. A.; Barzilov, A.; Harper, D.; Hopper, L.; Houchins, E.; Lemoff, B.; Martin, R.; McGrath, C.; Moore, R.; Novikov, I.; Paschal, J.; Rogers, S.

    2007-04-01

    Pressurized rail tank cars transport large volumes of volatile liquids and gases throughout the country, much of which is hazardous and/or flammable. These gases, once released in the atmosphere, can wreak havoc with the environment and local populations. We developed a system which can non-intrusively and non-invasively detect and locate pinhole-sized leaks in pressurized rail tank cars using acoustic sensors. The sound waves from a leak are produced by turbulence from the gas leaking to the atmosphere. For example, a 500 μm hole in an air tank pressurized to 689 kPa produces a broad audio frequency spectrum with a peak near 40 kHz. This signal is detectable at 10 meters with a sound pressure level of 25 dB. We are able to locate a leak source using triangulation techniques. The prototype of the system consists of a network of acoustic sensors and is located approximately 10 meters from the center of the rail-line. The prototype has two types of acoustic sensors, each with different narrow frequency response band: 40 kHz and 80 kHz. The prototype is connected to the Internet using WiFi (802.11g) transceiver and can be remotely operated from anywhere in the world. The paper discusses the construction, operation and performance of the system.

  15. 40 CFR 63.148 - Leak inspection provisions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Leak inspection provisions. 63.148 Section 63.148 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS... part 60, appendix A. (4) Calibration gases shall be as follows: (i) Zero air (less than 10 parts...

  16. Locating and sealing air leaks in multiroomed buildings

    NASA Technical Reports Server (NTRS)

    Britton, J. M.

    1968-01-01

    Industrial, nontoxic smoke bombs are used in multiroomed buildings to locate and fill discovered leak areas with polyurethane foam. All obvious air escape routes are sealed and the room is then pressurized to a minimum of 0.1 inch water above the pressure of adjoining rooms.

  17. VOLUMETRIC LEAK DETECTION IN LARGE UNDERGROUND STORAGE TANKS - VOLUME I

    EPA Science Inventory

    A set of experiments was conducted to determine whether volumetric leak detection system presently used to test underground storage tanks (USTs) up to 38,000 L (10,000 gal) in capacity could meet EPA's regulatory standards for tank tightness and automatic tank gauging systems whe...

  18. 10 CFR 36.59 - Detection of leaking sources.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of...

  19. 10 CFR 36.59 - Detection of leaking sources.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of...

  20. 10 CFR 36.59 - Detection of leaking sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of...

  1. 10 CFR 36.59 - Detection of leaking sources.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of...

  2. 84. Photocopied August 1978. REPAIRING FOREBAY LEAK, NOVEMBER 1907. THE ...

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

    84. Photocopied August 1978. REPAIRING FOREBAY LEAK, NOVEMBER 1907. THE PILE-DRIVER IS DRIVING NEW PILES FOR THE FOREBAY APRON, CLAY BACKFILL AND PLANKING CREWS ARE BUSY AT THE RIGHT. MUCH OF THE FOREBAY FLOOR WAS ALSO REPLANKED AT THIS TIME. (520) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  3. COPPER PITTING CORROSION AND PINHOLE LEAKS: A CASE STUDY

    EPA Science Inventory

    Localized corrosion, or "pitting", of copper drinking water pipe continues is a problem for many water utilities and their customers. Extreme attack leads to pinhole leaks that can potentially lead to water damage, mold growth, and costly repairs for the homeowners, as well as th...

  4. Valve leak detection for maintenance and thermal performance

    SciTech Connect

    Dimmick, J.G.; Mills, W.H.

    1988-01-01

    The theory and practical applications of the acoustic valve leak analyzer (AVLA) are discussed in this paper. Test procedures, analysis techniques, limitations, and results are presented, along with several case histories. It also presents information on check valve applications, which are routine for marine steam plants, but only recently of interest to utility engineers.

  5. Scrape on Endeavour's robotic arm during oxygen leak repairs

    NASA Technical Reports Server (NTRS)

    2002-01-01

    KENNEDY SPACE CENTER, FLA. -- Robotic arm experts begin inspection of a scrape on the surface of the honeycomb shell on Endeavour's robotic arm. The scrape occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of Endeavour on mission STS-113 has been postponed until no earlier than Nov. 22.

  6. Scrape on Endeavour's robotic arm during oxygen leak repairs

    NASA Technical Reports Server (NTRS)

    2002-01-01

    KENNEDY SPACE CENTER, FLA. -- Robotic arm experts get ready for ultrasound testing on Endeavour's robotic arm. A scrape of the honeycomb shell around the arm occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of Endeavour on mission STS-113 has been postponed until no earlier than Nov. 22.

  7. Scrape on Endeavour's robotic arm during oxygen leak repairs

    NASA Technical Reports Server (NTRS)

    2002-01-01

    KENNEDY SPACE CENTER, FLA. -- A piece of the honeycomb shell around Endeavour's robotic arm has been cut to inspect the arm. A scrape of the shell occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of Endeavour on mission STS-113 has been postponed until no earlier than Nov. 22.

  8. Scrape on Endeavour's robotic arm during oxygen leak repairs

    NASA Technical Reports Server (NTRS)

    2002-01-01

    KENNEDY SPACE CENTER, FLA. -- Robotic arm experts begin inspection of a scrape on the surface of the honeycomb shell on Endeavour's robotic arm. The scrape occurred while work platforms were being installed to gain access to repair the oxygen leak in the Shuttle's mid-body. Launch of Endeavour on mission STS-113 has been postponed until no earlier than Nov. 22..

  9. A Hydrazine Leak Sensor Based on Chemically Reactive Thermistors

    NASA Technical Reports Server (NTRS)

    Davis, Dennis D.; Mast, Dion J.; Baker, David L.

    1999-01-01

    Leaks in the hydrazine supply system of the Shuttle APU can result in hydrazine ignition and fire in the aft compartment of the Shuttle. Indication of the location of a leak could provide valuable information required for operational decisions. WSTF has developed a small, single use sensor for detection of hydrazine leaks. The sensor is composed of a thermistor bead coated with copper(II) oxide (CuO) dispersed in a clay or alumina binder. The CuO-coated thermistor is one of a pair of closely located thermistors, the other being a reference. On exposure to hydrazine the CuO reacts exothermically with the hydrazine and increases the temperature of the coated-thermistor by several degrees. The temperature rise is sensed by a resistive bridge circuit and an alarm registered by data acquisition software. Responses of this sensor to humidity changes, hydrazine concentration, binder characteristics, distance from a liquid leak, and ambient pressure levels as well as application of this sensor concept to other fluids are presented.

  10. 40 CFR 63.1255 - Standards: Equipment leaks.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) General equipment leak requirements. (1) The provisions of this section apply to pumps, compressors... connection systems. Section 63.169 applies to pumps, valves, connectors, and agitators in heavy liquid... or operator may not comply with the planned routine maintenance provisions in § 63.1252(h)....

  11. Monitoring plan for characterization of the Building 3019 leak site

    SciTech Connect

    Not Available

    1986-06-01

    The Oak Ridge National Laboratory (ORNL) has established a Remedial Action Program to provide comprehensive management of areas where past research, development, and waste management activities have resulted in residual contamination of facilities or the environment. In the winter of 1985, elevated levels of strontium-90 were detected in White Oak Creek and the ORNL sewage treatment plant. A leak was subsequently identified in a low-level waste transfer line north of Building 3019. The period of leakage and the exact chemical composition of the effluent are unknown. Two dye tests conducted at the leak site have identified several possible pathways for contaminant migration. The discovery of a solution cavity in the Chickamauga bedrock underlying the leak site and the rapid appearance of dye in the sump at Building 3042 indicate the extension of the cavity system along strike to the east. This report outlines the available published and unpublished background information pertaining to the site and proposes a monitoring plan consisting of soil sample collection and monitor well installation to provide a preliminary assessment of the types and extent of contamination at the leak site. The plan is also designed to provide additional geologic and hydrologic data for evaluating possible contaminant migration pathways. 6 refs., 10 figs., 1 tab.

  12. Leaks, Lumps, and Lines: Stigma and Women's Bodies

    ERIC Educational Resources Information Center

    Chrisler, Joan C.

    2011-01-01

    Women's bodies have often been positioned in art and popular culture as monstrous or defiled and women's bodily products (e.g., menstrual fluid, breast milk) as disgusting. This framing has led to the stigmatization of aspects of women's bodies (e.g., leaking fluids, lumps of fat, and lines in the skin that indicate aging), especially those…

  13. 40 CFR 1065.345 - Vacuum-side leak verification.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ....345 Section 1065.345 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calibrations and Verifications Flow-Related Measurements § 1065...) Measurement principles. A leak may be detected either by measuring a small amount of flow when there should...

  14. Analog Binaural Circuits for Detecting and Locating Leaks

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T.

    2003-01-01

    Very-large-scale integrated (VLSI) analog binaural signal-processing circuits have been proposed for use in detecting and locating leaks that emit noise in the ultrasonic frequency range. These circuits would be designed to function even in the presence of intense lower-frequency background noise that could include sounds associated with flow and pumping. Each of the proposed circuits would include the approximate electronic equivalent of a right and a left cochlea plus correlator circuits. A pair of transducers (microphones or accelerometers), corresponding to right and left ears, would provide the inputs to their respective cochleas from different locations (e.g., from different positions along a pipe). The correlation circuits plus some additional external circuits would determine the difference between the times of arrival of a common leak sound at the two transducers. Then the distance along the pipe from either transducer to the leak could be estimated from the time difference and the speed of sound along the pipe. If three or more pairs of transducers and cochlear/correlator circuits were available and could suitably be positioned, it should be possible to locate a leak in three dimensions by use of sound propagating through air.

  15. DETAIL OF JAMES LEAK CONFEDERATE HEADSTONE (RIGHT FOREGROUND), WITH CANNON, ...

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

    DETAIL OF JAMES LEAK CONFEDERATE HEADSTONE (RIGHT FOREGROUND), WITH CANNON, FLAGPOLE, CONFEDERATE MONUMENT, CANNONBALL PYRAMID AND ARC OF UNKNOWN U.S. SOLDIER HEADSTONES IN BACKGROUND. VIEW TO NORTHEAST. - Oak Woods Cemetery, Confederate Mound, 1035 East 67th Street, Chicago, Cook County, IL

  16. 40 CFR 63.148 - Leak inspection provisions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... readings for background. If an owner or operator elects to not adjust readings for background, all such... is a leak. If an owner or operator elects to adjust instrument readings for background, the owner or operator shall measure background concentration using the procedures in §§ 63.180(b) and (c) of subpart...

  17. 40 CFR 63.148 - Leak inspection provisions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... readings for background. If an owner or operator elects to not adjust readings for background, all such... is a leak. If an owner or operator elects to adjust instrument readings for background, the owner or operator shall measure background concentration using the procedures in §§ 63.180(b) and (c) of subpart...

  18. 40 CFR 63.148 - Leak inspection provisions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... readings for background. If an owner or operator elects to not adjust readings for background, all such... is a leak. If an owner or operator elects to adjust instrument readings for background, the owner or operator shall measure background concentration using the procedures in §§ 63.180(b) and (c) of subpart...

  19. 40 CFR 63.148 - Leak inspection provisions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... readings for background. If an owner or operator elects to not adjust readings for background, all such... is a leak. If an owner or operator elects to adjust instrument readings for background, the owner or operator shall measure background concentration using the procedures in §§ 63.180(b) and (c) of subpart...

  20. Consistent set of nuclear parameters values for absolute INAA

    SciTech Connect

    Heft, R.E.

    1980-01-01

    Gamma spectral analysis of irradiated material can be used to determine absolute disintegration rates for specific radionuclides. These data, together with measured values for the thermal and epithermal neutron fluxes, and irradiation, cooling and counting time values, are all the experimental information required to do absolute Instrumental Neutron Activation Analysis. The calculations required to go from product photon emission rate to target nuclide amount depend upon values used for the thermal neutron capture cross-section, the resonance absorption integral, the half-life and photon branching ratios. Values for these parameters were determined by irradiating and analyzing a series of elemental standards. The results of these measurements were combined with values reported by other workers to arrive at a set of recommended values for the constants. Values for 114 nuclides are listed.