Science.gov

Sample records for air leakage rates

  1. Effects of saline-water flow rate and air speed on leakage current in RTV coatings

    SciTech Connect

    Kim, S.H.; Hackam, R.

    1995-10-01

    Room temperature vulcanizing (RTV) silicone rubber is increasingly being used to coat porcelain and glass insulators in order to improve their electrical performance in the presence of pollution and moisture. A study of the dependence of leakage current, pulse current count and total charge flowing across the surface of RTV on the flow rate of the saline water and on the compressed air pressure used to create the salt-fog is reported. The fog was directed at the insulating rods either from one or two sides. The RTV was fabricated from polydimethylsiloxane polymer, a filler of alumina trihydrate (ATH), a polymerization catalyst and fumed silica reinforcer, all dispersed in 1,1,1-trichloroethane solvent. The saline water flow rate was varied in the range 0.4 to 2.0 l/min. The compressed air pressure at the input of the fog nozzles was varied from 0.20 to 0.63 MPa. The air speed at the surface of the insulating rods was found to depend linearly on the air pressure measured at the inlet to the nozzles and varied in the range 3 to 14 km/hr. The leakage current increased with increasing flow rate and increasing air speed. This is attributed to the increased loss of hydrophobicity with a larger quantity of saline fog and a larger impact velocities of fog droplets interacting with the surface of the RTV coating.

  2. 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'.

  3. Air leakage in residential solar heating systems

    NASA Astrophysics Data System (ADS)

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

    1981-02-01

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

  4. Air-leakage control manual

    SciTech Connect

    Maloney, J.

    1991-05-01

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

  5. Air-Leakage Control Manual.

    SciTech Connect

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

    1991-05-01

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

  6. Quantifying Molecular Hydrogen Emissions and an Industrial Leakage Rate for the South Coast Air Basin of California

    NASA Astrophysics Data System (ADS)

    Irish, M. C.; Schroeder, J.; Beyersdorf, A. J.; Blake, D. R.

    2015-12-01

    The poorly understood atmospheric budget and distribution of molecular hydrogen (H2) have invited further research since the discovery that emissions from a hydrogen-based economy could have negative impacts on the global climate system and stratospheric ozone. The burgeoning fuel cell electric vehicle industry in the South Coast Air Basin of California (SoCAB) presents an opportunity to observe and constrain urban anthropogenic H2 emissions. This work presents the first H2 emissions estimate for the SoCAB and calculates an upper limit for the current rate of leakage from production and distribution infrastructure within the region. A top-down method utilized whole air samples collected during the Student Airborne Research Program (SARP) onboard the NASA DC-8 research aircraft from 23-25 June 2015 to estimate H2 emissions from combustion and non-combustion sources. H2:carbon monoxide (CO) and H2:carbon dioxide ratios from airborne observations were compared with experimentally established ratios from pure combustion source ratios and scaled with the well-constrained CO emissions inventory to yield H2 emissions of 24.9 ± 3.6 Gg a-1 (1σ) from combustion engines and 8.2 ± 4.7 Gg a-1 from non-combustion sources. Total daily production of H2 in the SoCAB was compared with the top-down results to estimate an upper limit leakage rate (5%) where all emissions not accounted for by incomplete combustion in engines were assumed to be emitted from H2 infrastructure. For bottom-up validation, the NOAA Hybrid Single Particle Lagrangian Integrated Trajectory dispersion model was run iteratively with all known stationary sources in attempt to constrain emissions. While this investigation determined that H2 emissions from non-combustion sources in the SoCAB are likely significant, more in-depth analysis is required to better predict the atmospheric implications of a hydrogen economy.

  7. Residential Forced Air System Cabinet Leakage and Blower Performance

    SciTech Connect

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

    2010-03-01

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

  8. Air leakage of newly instaled residential windows

    SciTech Connect

    Weidt, J.; Weidt, J.

    1980-06-01

    The air-leakage characteristics of five major window designs were measured in a field survey conducted in Twin Cities, Minnesota. A total of 192 windows (16 manufacturers) were tested at 58 sites representing a cross-section of single-family homes, townhouses, low- and high-rise apartments, and condominiums. Air-leakage measurements of the installed windows were compared with the current standard used by industry and government of 0.50 ft/sup 3//min/linear ft of crack. Other parameters studied were: effect of sash and frame material, effect of leakage between window frame and wall, differences among the product lines of a single manufacturer and between manufacturers, effect of installation practices, effect of cold weather on performance, change in performance over time for older windows, and performance of fixed glazing. Based on industry and government standards, 40% of all windows tested showed air-leakage characteristics higher than the 0.50 cfm/lfc standard, and 60% exceeded manufacturers' specifications for performance which in some cases were lower than the general industry standard. Analysis of the impact of various parameters on air-leakage performance showed that the operational design of the window was the most critical determinant although the ranking changes if performance is expressed in cfm/unit area or cfm/opening area. Air leakage was measured using a portable pressurization chamber. Smoke pencils, thermographic techniques and extensive photographic documentation provided additional data as to the location and cause of air leakage problems.

  9. Control of Air Leakage in Buildings.

    ERIC Educational Resources Information Center

    Wilson, A. Grant

    This discussion of air leakage emphasizes cause and provides suggestions for elimination of undesirable effects. Cause parameters described are--(1) pressure differential, (2) building shape, (3) temperature differential, (4) opening sizes, (5) mechanical system pressures, and (6) climatic factors. Effects discussed are--(1) increased mechanical…

  10. Vacuum test fixture improves leakage rate measurements

    NASA Technical Reports Server (NTRS)

    Maier, H.; Marx, H.

    1966-01-01

    Cylindrical chamber, consisting of two matching halves, forms a vacuum test fixture for measuring leakage rates of individual connections, brazed joints, and entrance ports used in closed fluid flow line systems. Once the chamber has been sufficiently evacuated, atmospheric pressure holds the two halves together.

  11. The energy impact of air leakage through insulated walls

    SciTech Connect

    Bhattacharyya, S.; Claridge, D.E.

    1995-08-01

    Infiltration is customarily assumed to increase the heating and cooling load of a building by an amount equal to the mass flow rate of the infiltration times the enthalpy difference between the inside and outside air--with the latent portion of the enthalpy difference sometimes neglected. An experimental and analytical investigation has been conducted on the actual energy impact of air leakage on a well-characterized insulated stud-cavity wall specimen. Calorimetric measurements conducted on the specimen with measured amounts of air leakage introduced under a variety of controlled conditions and configurations verify earlier test cell measurements showing that infiltration heat exchange can lead to a much smaller change in the energy load due to infiltration than is customarily calculated and show the dependence of infiltration heat exchange on flow rate and path length. A analytical model based on fundamental heat and mass transfer principles has been developed and the predicted values of Infiltration Heat Exchange Effectiveness, {var_epsilon}, as a function of air flow rates and effective path length for five study-cavity wall specimen test configurations were consistent with the experimental results. Significant experimental results include: (i) {epsilon} values in the 0.16--0.7 range in the stud-cavity and (ii) {epsilon} values of 0.16 to 0.34 for air exiting the stud-cavity directly across from the entry. These results indicate that significant heat recovery is probable for most leakage occurring through insulated stud cavities.

  12. ANALYSIS OF MEASUREMENT UNCERTAINTIES IN THE NULLING TEST FOR AIR LEAKAGE FROM RESIDENTIAL DUCTS.

    SciTech Connect

    ANDREWS,J.W.

    2001-04-01

    An analysis of measurement uncertainties in a recently proposed method of measuring air leakage in residential duct systems has been carried out. The uncertainties in supply and return leakage rates are expressed in terms of the value of the envelope leakage flow coefficient and the uncertainties in measured pressures and air flow rates. Results of the analysis are compared with data published by two research groups.

  13. Measurements of the atmospheric neutron leakage rate

    NASA Technical Reports Server (NTRS)

    Lockwood, J. A.; Ifedili, S. O.; Jenkins, R. W.

    1973-01-01

    The atmospheric neutron leakage rate in the energy range from 0.01 to 10,000,000 eV has been measured as a function of latitude, altitude, and time with a neutron detector on board the Ogo 6 satellite. The latitude dependence of the neutron leakage is in reasonable agreement with that predicted by Lingenfelter (1963) and Light et al. (1973) if the neutron energy spectrum has the shape calculated by Newkirk (1963). The change in the neutron latitude dependence with the cosmic ray modulation agrees with the predictions of Lingenfelter and Light et al. For several solar proton events enhancements were observed in the neutron counting rates at lambda greater than or equal to 70 deg. Such events, however, provide an insignificant injection of protons at E less than or equal to 20 MeV into the radiation belts. An isotropic angular distribution of the neutron leakage in the energy range from 0.1 keV to 10 MeV best fits the observed altitude dependence of the neutron leakage flux.

  14. Air Leakage and Air Transfer Between Garage and Living Space

    SciTech Connect

    Rudd, Armin

    2014-09-01

    This research project focused on evaluation of air transfer between the garage and living space in a single-family detached home constructed by a production homebuilder in compliance with the 2009 International Residential Code and the 2009 International Energy Conservation Code. The project gathered important information about the performance of whole-building ventilation systems and garage ventilation systems as they relate to minimizing flow of contaminated air from garage to living space. A series of 25 multi-point fan pressurization tests and additional zone pressure diagnostic testing characterized the garage and house air leakage, the garage-to-house air leakage, and garage and house pressure relationships to each other and to outdoors using automated fan pressurization and pressure monitoring techniques. While the relative characteristics of this house may not represent the entire population of new construction configurations and air tightness levels (house and garage) throughout the country, the technical approach was conservative and should reasonably extend the usefulness of the results to a large spectrum of house configurations from this set of parametric tests in this one house. Based on the results of this testing, the two-step garage-to-house air leakage test protocol described above is recommended where whole-house exhaust ventilation is employed.

  15. Air Leakage and Air Transfer Between Garage and Living Space

    SciTech Connect

    Rudd, A.

    2014-09-01

    This research project focused on evaluation of air transfer between the garage and living space in a single-family detached home constructed by a production homebuilder in compliance with the 2009 International Residential Code and the 2009 International Energy Conservation Code. The project gathered important information about the performance of whole-building ventilation systems and garage ventilation systems as they relate to minimizing flow of contaminated air from garage to living space. A series of 25 multi-point fan pressurization tests and additional zone pressure diagnostic testing characterized the garage and house air leakage, the garage-to-house air leakage, and garage and house pressure relationships to each other and to outdoors using automated fan pressurization and pressure monitoring techniques. While the relative characteristics of this house may not represent the entire population of new construction configurations and air tightness levels (house and garage) throughout the country, the technical approach was conservative and should reasonably extend the usefulness of the results to a large spectrum of house configurations from this set of parametric tests in this one house. Based on the results of this testing, the two-step garage-to-house air leakage test protocol described above is recommended where whole-house exhaust ventilation is employed. For houses employing whole-house supply ventilation (positive pressure) or balanced ventilation (same pressure effect as the Baseline condition), adherence to the EPA Indoor airPLUS house-to-garage air sealing requirements should be sufficient to expect little to no garage-to-house air transfer.

  16. Indoor-Outdoor Air Leakage of Apartments and Commercial Buildings

    SciTech Connect

    Price, P.N.; Shehabi, A.; Chan, R.W.; Gadgil, A.J.

    2006-06-01

    We compiled and analyzed available data concerning indoor-outdoor air leakage rates and building leakiness parameters for commercial buildings and apartments. We analyzed the data, and reviewed the related literature, to determine the current state of knowledge of the statistical distribution of air exchange rates and related parameters for California buildings, and to identify significant gaps in the current knowledge and data. Very few data were found from California buildings, so we compiled data from other states and some other countries. Even when data from other developed countries were included, data were sparse and few conclusive statements were possible. Little systematic variation in building leakage with construction type, building activity type, height, size, or location within the u.s. was observed. Commercial buildings and apartments seem to be about twice as leaky as single-family houses, per unit of building envelope area. Although further work collecting and analyzing leakage data might be useful, we suggest that a more important issue may be the transport of pollutants between units in apartments and mixed-use buildings, an under-studied phenomenon that may expose occupants to high levels of pollutants such as tobacco smoke or dry cleaning fumes.

  17. Air-leakage effects on stone cladding panels

    NASA Astrophysics Data System (ADS)

    Colantonio, Antonio

    1995-03-01

    This paper looks at the effects of air leakage on insulated stone clad precast panels used in present day construction of large commercial buildings. The building investigated was a newly built twenty story office building in a high density urban setting. Air leakage was suspected as a possible cause for thermal comfort complaints at isolated locations within the perimeter zones of the building. During the warrantee period the building owner asked for a quality control inspection of the air barrier assembly of the building envelope. Infrared thermography was used to locate areas of suspected air leakage within the building envelope. In order to differentiate thermal patterns produced by air leakage, conduction and convection as well as radiation from external sources, the building was inspected from the exterior; (1) after being pressurized for three hours, (2) one hour after the building was depressurized and (3) two and a half hours after total building depressurization was maintained by the building mechanical systems. Thermal images from similar locations were correlated for each time and pressure setting to verify air leakage locations within the building envelope. Areas exhibiting air leakage were identified and contractors were requested to carry out the necessary repairs. The pressure differential across the building envelope needs to be known in order to properly carry out an inspection to identify all locations of air leakage within a building envelope. As well the direction of the air movement and the density of the cladding material need to be accounted for in the proper inspection of these types of wall assemblies.

  18. Estimation of leakage rates through flexible membrane liners

    SciTech Connect

    Murray, G.B.; McBean, E.A.; Sykes, J.F.

    1995-12-31

    Leakage rate calculations for both low-permeability soil liners and composite liners using flexible membrane liners (FMLs) overlying low-permeability soil are developed. Latin-Hypercube simulations with uncertainty assigned to the soil liner hydraulic conductivity value and the spatial frequency of FML holes are used to examine the variability in the liner leakage rats. The low-permeability soil hydraulic conductivity is the parameter with the greatest effect on landfill liner leakages rates. Composite liners have a significant impact on reducing leakage rates through the landfill liner.

  19. 40 CFR 86.166-12 - Method for calculating emissions due to air conditioning leakage.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... determine a refrigerant leakage rate in grams per year from vehicle-based air conditioning units. The... using the following equation: Grams/YRTOT = Grams/YRRP + Grams/YRSP + Grams/YRFH + Grams/YRMC + Grams/YRC Where: Grams/YRTOT = Total air conditioning system emission rate in grams per year and rounded...

  20. Air Leakage of U.S. Homes: Model Prediction

    SciTech Connect

    Sherman, Max H.; McWilliams, Jennifer A.

    2007-01-01

    Air tightness is an important property of building envelopes. It is a key factor in determining infiltration and related wall-performance properties such as indoor air quality, maintainability and moisture balance. Air leakage in U.S. houses consumes roughly 1/3 of the HVAC energy but provides most of the ventilation used to control IAQ. The Lawrence Berkeley National Laboratory has been gathering residential air leakage data from many sources and now has a database of more than 100,000 raw measurements. This paper uses a model developed from that database in conjunction with US Census Bureau data for estimating air leakage as a function of location throughout the US.

  1. 40 CFR 264.252 - Action leakage rate.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Action leakage rate. 264.252 Section 264.252 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Waste Piles § 264.252 Action leakage rate. (a)...

  2. 40 CFR 265.222 - Action leakage rate.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) INTERIM STATUS STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Surface Impoundments § 265.222 Action leakage rate. (a) The owner or operator of surface...) The Regional Administrator shall approve an action leakage rate for surface impoundment units...

  3. 40 CFR 265.222 - Action leakage rate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) INTERIM STATUS STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Surface Impoundments § 265.222 Action leakage rate. (a) The owner or operator of surface...) The Regional Administrator shall approve an action leakage rate for surface impoundment units...

  4. 40 CFR 264.222 - Action leakage rate.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Action leakage rate. 264.222 Section 264.222 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Surface Impoundments § 264.222 Action leakage...

  5. Urban leakage of liquefied petroleum gas and its impact on Mexico City air quality

    SciTech Connect

    Blake, D.R.; Rowland, F.S.

    1995-08-18

    Alkane hydrocarbons (propane, isobutane, and n-butane) from liquefied petroleum gas (LPG) are present in major quantities throughout Mexico City air because of leakage of the unburned gas from numerous urban sources. These hydrocarbons, together with olefinic minor LPG components, furnish substantial amounts of hydroxyl radical reactivity, a major precursor to formation of the ozone component of urban smog. The combined processes of unburned leakage and incomplete combustion of LPG play significant role in causing the excessive ozone characteristic of Mexico City. Reductions in ozone levels should be possible through changes in LPG composition and lowered rates of leakage. 23 refs., 3 tabs.

  6. Analyzing a database of residential air leakage in the United States

    NASA Astrophysics Data System (ADS)

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

    We analyzed more than 70,000 air leakage measurements in houses across the United States to relate leakage area—the effective size of all penetrations of the building shell—to readily available building characteristics such as building size, year built, geographic region, and various construction characteristics. After adjusting for the lack of statistical representativeness of the data, we found that the distribution of leakage area normalized by floor area is approximately lognormal. Based on a classification tree analysis, year built and floor area are the two most significant predictors of leakage area: older and smaller houses tend to have higher normalized leakage areas than newer and larger ones. Multivariate regressions of normalized leakage are presented with respect to these two factors for three house classifications: low-income households, energy program houses, and conventional houses. We demonstrate a method of applying the regression model to housing characteristics from the American Housing Survey to derive a leakage-area distribution for all single-family houses in the US. The air exchange rates implied by these estimates agree reasonably well with published measurements.

  7. 40 CFR 264.252 - Action leakage rate.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Action leakage rate. 264.252 Section 264.252 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... flow rate that the leak detection system (LDS) can remove without the fluid head on the bottom...

  8. 40 CFR 264.252 - Action leakage rate.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 26 2014-07-01 2014-07-01 false Action leakage rate. 264.252 Section 264.252 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... flow rate that the leak detection system (LDS) can remove without the fluid head on the bottom...

  9. 40 CFR 264.252 - Action leakage rate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Waste... for waste pile units subject to § 264.251(c) or (d). The action leakage rate is the maximum design..., operation, and location of the LDS, waste and leachate characteristics, likelihood and amounts of...

  10. 40 CFR 264.252 - Action leakage rate.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Waste... for waste pile units subject to § 264.251(c) or (d). The action leakage rate is the maximum design..., operation, and location of the LDS, waste and leachate characteristics, likelihood and amounts of...

  11. 40 CFR 265.255 - Action leakage rates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Action leakage rates. 265.255 Section 265.255 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) INTERIM STATUS STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Waste Piles § 265.255...

  12. 40 CFR 265.302 - Action leakage rate.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Action leakage rate. 265.302 Section 265.302 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) INTERIM STATUS STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Landfills § 265.302 Action...

  13. 40 CFR 265.302 - Action leakage rate.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Action leakage rate. 265.302 Section 265.302 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) INTERIM STATUS STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Landfills § 265.302 Action...

  14. 40 CFR 265.222 - Action leakage rate.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 26 2014-07-01 2014-07-01 false Action leakage rate. 265.222 Section 265.222 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... system (LDS) can remove without the fluid head on the bottom liner exceeding 1 foot. The action...

  15. 40 CFR 265.222 - Action leakage rate.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 27 2013-07-01 2013-07-01 false Action leakage rate. 265.222 Section 265.222 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... system (LDS) can remove without the fluid head on the bottom liner exceeding 1 foot. The action...

  16. 40 CFR 265.222 - Action leakage rate.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 27 2012-07-01 2012-07-01 false Action leakage rate. 265.222 Section 265.222 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... system (LDS) can remove without the fluid head on the bottom liner exceeding 1 foot. The action...

  17. Moisture Risk in Unvented Attics Due to Air Leakage Paths

    SciTech Connect

    Prahl, D.; Shaffer, M.

    2014-11-01

    IBACOS completed an initial analysis of moisture damage potential in an unvented attic insulated with closed-cell spray polyurethane foam. To complete this analysis, the research team collected field data, used computational fluid dynamics to quantify the airflow rates through individual airflow (crack) paths, simulated hourly flow rates through the leakage paths with CONTAM software, correlated the CONTAM flow rates with indoor humidity ratios from Building Energy Optimization software, and used Warme und Feuchte instationar Pro two-dimensional modeling to determine the moisture content of the building materials surrounding the cracks. Given the number of simplifying assumptions and numerical models associated with this analysis, the results indicate that localized damage due to high moisture content of the roof sheathing is possible under very low airflow rates. Reducing the number of assumptions and approximations through field studies and laboratory experiments would be valuable to understand the real-world moisture damage potential in unvented attics.

  18. Moisture Risk in Unvented Attics Due to Air Leakage Paths

    SciTech Connect

    Prahl, D.; Shaffer, M.

    2014-11-01

    IBACOS completed an initial analysis of moisture damage potential in an unvented attic insulated with closed-cell spray polyurethane foam. To complete this analysis, the research team collected field data, used computational fluid dynamics to quantify the airflow rates through individual airflow (crack) paths, simulated hourly flow rates through the leakage paths with CONTAM software, correlated the CONTAM flow rates with indoor humidity ratios from Building Energy Optimization software, and used Wärme und Feuchte instationär Pro two-dimensional modeling to determine the moisture content of the building materials surrounding the cracks. Given the number of simplifying assumptions and numerical models associated with this analysis, the results indicate that localized damage due to high moisture content of the roof sheathing is possible under very low airflow rates. Reducing the number of assumptions and approximations through field studies and laboratory experiments would be valuable to understand the real-world moisture damage potential in unvented attics.

  19. Combination Of Thermography And Pressure Tests To Combat Air Leakage Problems In Building Enclosures

    NASA Astrophysics Data System (ADS)

    Spruin, W. G.

    1987-05-01

    Uncontrolled air leakage in a building enclosure is the main component of space heating and cooling costs. In Atlantic Canada, Public Works Canada has combined thermography and pressure testing to identify design and construction problems in new construction and to identify specific areas of air leakage in existing housing stock. A study case shows how thermography and pressure testing has been utilized to locate and compare specific areas of air leakage in a residence before and after air sealing. The study provides both quantitative and qualitative evidence of how air sealing increases the air tightness in building enclosures.

  20. Technology Solutions Case Study: Air Leakage and Air Transfer Between Garage and Living Space, Waldorf, Maryland

    SciTech Connect

    2014-11-01

    In this project, Building Science Corporation worked with production homebuilder K. Hovnanian to evaluate air transfer between the garage and living space in a single-family detached home constructed by a production homebuilder in compliance with the 2009 International Residential Code and the 2009 International Energy Conservation Code. The project gathered important information about the performance of whole-building ventilation systems and garage ventilation systems as they relate to minimizing flow of contaminated air from garage to living space. A series of 25 multipoint fan pressurization tests and additional zone pressure diagnostic testing measured the garage and house air leakage, the garage-to-house air leakage, and garage and house pressure relationships to each other and to outdoors using automated fan pressurization and pressure monitoring techniques. While the relative characteristics of this house may not represent the entire population of new construction configurations and air tightness levels (house and garage) throughout the country, the technical approach was conservative and should reasonably extend the usefulness of the results to a large spectrum of house configurations from this set of parametric tests in this one house. Based on the results of this testing, the two-step garage-to-house air leakage test protocol described above is recommended where whole-house exhaust ventilation is employed. For houses employing whole-house supply ventilation (positive pressure) or balanced ventilation (same pressure effect as the baseline condition), adherence to the EPA Indoor airPLUS house-to-garage air sealing requirements should be sufficient to expect little to no garage-to-house air transfer.

  1. The measured energy impact of air leakage on frame wall systems

    SciTech Connect

    Bhattacharyya, S.

    1991-06-01

    Infiltration is customarily assumed to increase the heating and cooling load of a building by an amount equal to the mass flow rate of the infiltration times the enthalpy difference between the inside and outside air -- with the latent portion of the enthalpy difference sometimes neglected. An experimental and analytical investigation has been conducted on the actual energy impact of air leakage on frame wall systems. Calorimetric measurements conducted on a small test cell and on a well characterized stud-cavity wall specimen with measured amounts of air leakage introduced under a variety of controlled conditions and configurations show convincingly that infiltration can lead to a much smaller change in the energy load than is customarily calculated. The data also suggest that the phenomenon occurs in full-sized houses as well. Infiltration Heat Exchange Effectiveness (IHEE),{var epsilon}, is introduced as a measure of the effectiveness of a building in recovering'' heat otherwise lost (or gained) because of infiltration. Measurements show that {var epsilon} increases as: (a) flow rate decreases; (b) flow path length increases; and, (c) hole/crack size decreases.

  2. The measured energy impact of air leakage on frame wall systems. Final report

    SciTech Connect

    Bhattacharyya, S.

    1991-06-01

    Infiltration is customarily assumed to increase the heating and cooling load of a building by an amount equal to the mass flow rate of the infiltration times the enthalpy difference between the inside and outside air -- with the latent portion of the enthalpy difference sometimes neglected. An experimental and analytical investigation has been conducted on the actual energy impact of air leakage on frame wall systems. Calorimetric measurements conducted on a small test cell and on a well characterized stud-cavity wall specimen with measured amounts of air leakage introduced under a variety of controlled conditions and configurations show convincingly that infiltration can lead to a much smaller change in the energy load than is customarily calculated. The data also suggest that the phenomenon occurs in full-sized houses as well. Infiltration Heat Exchange Effectiveness (IHEE),{var_epsilon}, is introduced as a measure of the effectiveness of a building in ``recovering`` heat otherwise lost (or gained) because of infiltration. Measurements show that {var_epsilon} increases as: (a) flow rate decreases; (b) flow path length increases; and, (c) hole/crack size decreases.

  3. Failure Monitoring and Leakage Detection for Underground Storage of Compressed Air Energy in Lined Rock Caverns

    NASA Astrophysics Data System (ADS)

    Kim, Hyung-Mok; Rutqvist, Jonny; Kim, Hyunwoo; Park, Dohyun; Ryu, Dong-Woo; Park, Eui-Seob

    2016-02-01

    Underground compressed air energy storage (CAES) in lined rock caverns (LRCs) provides a promising solution for storing energy on a large scale. One of the essential issues facing underground CAES implementation is the risk of air leakage from the storage caverns. Compressed air may leak through an initial defect in the inner containment liner, such as imperfect welds and construction joints, or through structurally damaged points of the liner during CAES operation for repeated compression and decompression cycles. Detection of the air leakage and identification of the leakage location around the underground storage cavern are required. In this study, we analyzed the displacement (or strain) monitoring method to detect the mechanical failure of liners that provides major pathways of air leakage using a previously developed numerical technique simulating the coupled thermodynamic and geomechanical behavior of underground CAES in LRCs. We analyzed the use of pressure monitoring to detect air leakage and characterize the leakage location. From the simulation results, we demonstrated that tangential strain monitoring at the inner face of sealing liners could enable one to detect failure. We also demonstrated that the use of the cross-correlation method between pressure history data measured at various sensors could identify the air leak location. These results may help in the overall design of a monitoring and alarm system for the successful implementation and operation of CAES in LRCs.

  4. A study of leakage rates through mine seals in underground coal mines

    PubMed Central

    Schatzel, Steven J.; Krog, Robert B.; Mazzella, Andrew; Hollerich, Cynthia; Rubinstein, Elaine

    2015-01-01

    The National Institute for Occupational Safety and Health conducted a study on leakage rates through underground coal mine seals. Leakage rates of coal bed gas into active workings have not been well established. New seal construction standards have exacerbated the knowledge gap in our understanding of how well these seals isolate active workings near a seal line. At a western US underground coal mine, we determined seal leakage rates ranged from about 0 to 0.036 m3/s for seven 340 kPa seals. The seal leakage rate varied in essentially a linear manner with variations in head pressure at the mine seals. PMID:26322119

  5. SENSITIVITY OF THE HOUSE PRESSURE TEST FOR DUCT LEAKAGE TO VARIATIONS IN THE DISTRIBUTION OF AIR LEAKAGE IN THE HOUSE ENVELOPE

    SciTech Connect

    ANDREWS,J.W.

    1998-12-01

    The house pressure test for air leakage in ducts calculates the signed difference between the supply and return leakage from the response of the air pressure in the house to operation of the system fan. The currently accepted version of this calculation was based on particular assumptions about how the house envelope leakage is distributed between the walls, ceiling, and floor. This report generalizes the equation to account for an arbitrary distribution of envelope leakage. It concludes that the currently accepted equation is usually accurate to within {+-}5%, but in a small proportion of cases the results may diverge by 50% or more.

  6. Sensitivity of the house pressure test for duct leakage to variations in the distribution of air leakage in the house envelope

    SciTech Connect

    Andrews, J.W.

    1998-12-01

    The house pressure test for air leakage in ducts calculates the signed difference between the supply and return leakage from the response of the air pressure in the house to operation of the system fan. The currently accepted version of this calculation was based on particular assumptions about how the house envelope leakage is distributed between the walls, ceiling, and floor. This report generalizes the equation to account for an arbitrary distribution of envelope leakage. It concludes that the currently accepted equation is usually accurate to within {+-}5%, but in a small proportion of cases the results may diverge by 50% or more.

  7. Building America Top Innovations 2014 Profile: HVAC Cabinet Air Leakage Test Method

    SciTech Connect

    none,

    2014-11-01

    This 2014 Top Innovation profile describes Building America-funded research by teams and national laboratories that resulted in the development of an ASHRAE standard and a standardized testing method for testing the air leakage of HVAC air handlers and furnace cabinets and has spurred equipment manufacturers to tighten the cabinets they use for residential HVAC systems.

  8. 40 CFR 86.166-12 - Method for calculating emissions due to air conditioning leakage.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Method for calculating emissions due to air conditioning leakage. 86.166-12 Section 86.166-12 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for...

  9. 40 CFR 86.166-12 - Method for calculating emissions due to air conditioning leakage.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Method for calculating emissions due to air conditioning leakage. 86.166-12 Section 86.166-12 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES Emission Regulations for...

  10. The effect of air leakage and heat exchange on the decay of entrapped air pocket slamming oscillations

    NASA Astrophysics Data System (ADS)

    Abrahamsen, Bjørn C.; Faltinsen, Odd M.

    2011-10-01

    The phenomenon studied in this work is that of an air pocket entrapped by a free surface water wave inside a rectangular tank at a high filling level. The wave, which is a gravity wave, is caused by forced horizontal motion which is constructed in a particular way, in order to entrap an air pocket as it approaches the upper left corner of the tank. As the wave touches the roof, the air is compressed and starts to oscillate. The oscillations resemble, to some extent, the free oscillations of an underdamped mass-spring system, where the mass is related to the generalized added mass effect of the water pressure associated with the air pocket oscillations. The stiffness is due to the compressibility of the air. The reason for the damping or, more generally, the decay of the air pocket oscillations is less understood. Air leakage has been proposed as one possible reason for this decay. In this work, the role of air leakage is found not to be the reason for the decay of the air pocket oscillations, because it is not present during major parts of the impact. However, by drilling holes in the roof of the tank, the effect of leakage during the oscillations is proven to cause decay. To explain the physical source of the decay of the oscillations, damping due to heat transfer to and from the air pocket is investigated through an analytical one-dimensional steady-state model. The damping due to heat transfer is observed to play an important role. The obtained understanding of the mechanisms causing the decay of the air-pocket impact at the upper corner is believed to be relevant to other types of impacts, particularly the entrapment of air pockets on walls by breaking waves.

  11. On the Fluid Leakage Rate and Pressure Evaluation of Abandoned Non-Penetrating Wells.

    NASA Astrophysics Data System (ADS)

    Islam, J.; Zhan, H.

    2014-12-01

    Understanding flow leakage through abandoned wells that are potential pathways of contamination due to injecting unwanted fluids in geologically deep storage aquifers have become an intensively investigated subject in the subsurface hydrology and petroleum engineering. This study represents a semi-analytical transient solution for estimating leakage rate by pressure change evaluation through an abandoned non-penetrating well (ANW) coupled with an injection well. The leakage rate can be estimated using the Darcy's law by evaluating pressure change between the upper and the lower aquifers through ANW. The analysis was conducted by solving the diffusivity equations of fluid flow in the aquifer coupled with the pipe flow through ANW. The single-phase flow is considered in this study that is capable of explaining both fluid and CO2 plume flow in an aquifer system by neglecting the variable density effect. The result is compared with that of Avci's (1994) which dealt with an abandoned fully penetrating well. The result indicates the similar type of curve trend, which is observed by applying a range of aquifer properties as well as distance between the injection and leakage pathway. The important finding is that the leakage rate through ANW is about 50% compared to the fully penetrating well of Avci's (1994). The sensitivity analyses indicate that parameter leakage coefficient (A), transmissivity ratio (TD) and radial distance (R) between injection and ANW are the most sensitive to the leakage rate and the rest of the parameters are less sensitive. Because of availability of limited analytical and complex numerical solution, this simple new approach is going to provide a simple means to estimate leakage flow for realistic field condition.

  12. 40 CFR 265.255 - Action leakage rates.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... layover and creep of synthetic components of the system, overburden pressures, etc.). (c) To determine if... daily flow rate for each sump must be calculated weekly during the active life and closure period....

  13. 40 CFR 265.255 - Action leakage rates.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... layover and creep of synthetic components of the system, overburden pressures, etc.). (c) To determine if... daily flow rate for each sump must be calculated weekly during the active life and closure period....

  14. 40 CFR 264.222 - Action leakage rate.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... and creep of synthetic components of the system, overburden pressures, etc.). (b) To determine if the... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  15. 40 CFR 265.302 - Action leakage rate.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... layover and creep of synthetic components of the system, overburden pressures, etc.). (c) To determine if... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  16. 40 CFR 264.302 - Action leakage rate.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... and creep of synthetic components of the system, overburden pressures, etc.). (b) To determine if the... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  17. 40 CFR 264.222 - Action leakage rate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... and creep of synthetic components of the system, overburden pressures, etc.). (b) To determine if the... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  18. 40 CFR 264.302 - Action leakage rate.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... and creep of synthetic components of the system, overburden pressures, etc.). (b) To determine if the... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  19. 40 CFR 264.302 - Action leakage rate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... and creep of synthetic components of the system, overburden pressures, etc.). (b) To determine if the... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  20. 40 CFR 265.302 - Action leakage rate.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... layover and creep of synthetic components of the system, overburden pressures, etc.). (c) To determine if... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  1. 40 CFR 264.302 - Action leakage rate.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... and creep of synthetic components of the system, overburden pressures, etc.). (b) To determine if the... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  2. 40 CFR 265.255 - Action leakage rates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... layover and creep of synthetic components of the system, overburden pressures, etc.). (c) To determine if... daily flow rate for each sump must be calculated weekly during the active life and closure period....

  3. 40 CFR 264.302 - Action leakage rate.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... and creep of synthetic components of the system, overburden pressures, etc.). (b) To determine if the... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  4. 40 CFR 265.302 - Action leakage rate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... layover and creep of synthetic components of the system, overburden pressures, etc.). (c) To determine if... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  5. 40 CFR 265.255 - Action leakage rates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... layover and creep of synthetic components of the system, overburden pressures, etc.). (c) To determine if... daily flow rate for each sump must be calculated weekly during the active life and closure period....

  6. 40 CFR 264.222 - Action leakage rate.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... and creep of synthetic components of the system, overburden pressures, etc.). (b) To determine if the... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  7. 40 CFR 264.222 - Action leakage rate.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... and creep of synthetic components of the system, overburden pressures, etc.). (b) To determine if the... average daily flow rate for each sump must be calculated weekly during the active life and closure...

  8. Building America Case Study: Air Leakage and Air Transfer Between Garage and Living Space, Waldorf, Maryland (Fact Sheet)

    SciTech Connect

    Not Available

    2014-11-01

    This research project focused on evaluation of air transfer between the garage and living space in a single-family detached home constructed by a production homebuilder in compliance with the 2009 International Residential Code and the 2009 International Energy Conservation Code. The project gathered important information about the performance of whole-building ventilation systems and garage ventilation systems as they relate to minimizing flow of contaminated air from garage to living space. A series of 25 multi-point fan pressurization tests and additional zone pressure diagnostic testing characterized the garage and house air leakage, the garage-to-house air leakage, and garage and house pressure relationships to each other and to outdoors using automated fan pressurization and pressure monitoring techniques. While the relative characteristics of this house may not represent the entire population of new construction configurations and air tightness levels (house and garage) throughout the country, the technical approach was conservative and should reasonably extend the usefulness of the results to a large spectrum of house configurations from this set of parametric tests in this one house. Based on the results of this testing, the two-step garage-to-house air leakage test protocol described above is recommended where whole-house exhaust ventilation is employed. For houses employing whole-house supply ventilation (positive pressure) or balanced ventilation (same pressure effect as the Baseline condition), adherence to the EPA Indoor airPLUS house-to-garage air sealing requirements should be sufficient to expect little to no garage-to-house air transfer.

  9. The Thermal Performance and Air Leakage Characteristics of Six Log Homes in Idaho.

    SciTech Connect

    Roos, Carolyn; Eklund, Ken; Baylon, David

    1993-08-01

    The thermal performance and air leakage characteristics of four electrically heated log houses located in Idaho are summarized. The air leakage and construction characteristics of two additional log homes are also examined. The energy consumption of the four homes was submetered at weekly reporting intervals for up to 16 months. Blower door tests and site audits were performed. In addition, conditions at two of these homes, including heat flux through the log walls, indoor and outdoor temperatures, solar flux and envelope tightness, were measured in detail over several days during winter conditions. The energy use and thermal performance of these two homes were then modeled using SUNCODE-PC, an hourly thermal simulation program employing a finite difference technique.

  10. Air leakage on the postoperative day: powerful factor of postoperative recurrence after thoracoscopic bullectomy

    PubMed Central

    Jeon, Hyun Woo; Kye, Yeo Kon; Kim, Kyung Soo

    2016-01-01

    Background Primary spontaneous pneumothorax (PSP) is a relatively common disorder in young patients. Although various surgical techniques have been introduced, recurrence after video-assisted thoracoscopic surgery (VATS) remains high. The aim of study was to identify the risk factors for postoperative recurrence after thoracoscopic bullectomy in the spontaneous pneumothorax. Methods From January 2011 through March 2013, two hundreds and thirty two patients underwent surgery because of pneumothorax. Patients with a secondary pneumothorax, as well as cases of single port surgery, an open procedure, additional pleural procedure (pleurectomy, pleural abrasion) or lack of medical records were excluded. The records of 147 patients with PSP undergoing 3-port video-assisted thoracoscopic bullectomy with staple line coverage using an absorbable polyglycolic acid (PGA) sheet were retrospectively reviewed. Results The median age was 19 years (range, 11−34 years) with male predominance (87.8%). Median postoperative hospital stay was 3 days (range, 1−10 days) without mortality. Complications were developed in five patients. A total of 24 patients showed postoperative recurrence (16.3%). Younger age less than 17 years old and immediate postoperative air leakage were risk factors for postoperative recurrence after thoracoscopic bullectomy by multivariate analysis. Conclusions Immediate postoperative air leakage was the risk factor for postoperative recurrence. However, further study will be required for the correlation of air leakage with recurrence. PMID:26904217

  11. Effect of vadose zone on the steady-state leakage rates from landfill barrier systems

    SciTech Connect

    Celik, B. Rowe, R.K. Unlue, K.

    2009-01-15

    Leakage rates are evaluated for a landfill barrier system having a compacted clay liner (CCL) underlain by a vadose zone of variable thickness. A numerical unsaturated flow model SEEP/W is used to simulate the moisture flow regime and steady-state leakage rates for the cases of unsaturated zones with different soil types and thicknesses. The results of the simulations demonstrate that harmonic mean hydraulic conductivity of coarse textured vadose zones is 3-4 orders of magnitude less than saturated hydraulic conductivity; whereas, the difference is only one order of magnitude for fine textured vadose zones. For both coarse and fine textured vadose zones, the effective hydraulic conductivity of the barrier system and the leakage rate to an underlying aquifer increases with increasing thickness of the vadose zone and ultimately reaches an asymptotic value for a coarse textured vadose zone thickness of about 10 m and a fine textured vadose zone thickness of about 5 m. Therefore, the fine and coarse textured vadose zones thicker than about 5 m and 10 m, respectively, act as an effective part of the barrier systems examined. Although the thickness of vadose zone affects the effective hydraulic conductivity of the overall barrier system, the results demonstrated that the hydraulic conductivity of the CCL is the dominant factor controlling the steady-state leakage rates through barrier systems having single low permeability clay layers.

  12. Vent and relief valve maintains low leakage rate over broad temperature range

    NASA Technical Reports Server (NTRS)

    Weitenbeck, R. G.

    1968-01-01

    Low leakage rate, large diameter vent and relief valve operates satisfactorily over a large temperature range by a design that accommodates waviness and distortions due to thermal gradients. It is based on a fixed sealing member having an inclined lapped surface to which a flexible flow gate conforms.

  13. Fluctuations and the Rate-Limiting Step of Peptide-Induced Membrane Leakage

    PubMed Central

    Mazzuca, C.; Orioni, B.; Coletta, M.; Formaggio, F.; Toniolo, C.; Maulucci, G.; De Spirito, M.; Pispisa, B.; Venanzi, M.; Stella, L.

    2010-01-01

    Peptide-induced vesicle leakage is a common experimental test for the membrane-perturbing activity of antimicrobial peptides. The leakage kinetics is usually very slow, requiring minutes to hours for complete release of vesicle contents, and exhibits a biphasic behavior. We report here that, in the case of the peptaibol trichogin GA IV, all processes involved in peptide-membrane interaction, such as peptide-membrane association, peptide aggregation, and peptide translocation, take place on a timescale much shorter than the leakage kinetics. On the basis of these findings, we propose a stochastic model in which the leakage kinetics is determined by the discrete nature of a vesicle suspension: peptides are continuously exchanging among vesicles, producing significant fluctuations over time in the number of peptide molecules bound to each vesicle, and in the formation of pores. According to this model, the fast initial leakage is caused by vesicles that contain at least one pore after the peptides are randomly distributed among the liposomes, whereas the slower release is associated with the time needed to occasionally reach in an intact vesicle the critical number of bound peptides necessary for pore formation. Fluctuations due to peptide exchange among vesicles therefore represent the rate-limiting step of such a slow mechanism. PMID:20858423

  14. Space Station Freedom delta pressure leakage rate comparison test data analysis report

    NASA Technical Reports Server (NTRS)

    Sorensen, E. B.

    1992-01-01

    Results are provided of a series of tests performed to identify the relationship between gas leakage rates across a seal at various internal to external pressure ratios. The results complement and provide insight into the analysis technique used to obtain the results presented in MSFC SSF/DEV/EL91-008, 'Space Station Freedom (S.S. Freedom) Seal Flaw Study with Delta Pressure Leak Rate Comparison Test Report.'

  15. Seatbelt syndrome with gastric mucosal breaks and intra-gastric wall air leakage.

    PubMed

    Mori, Hirohito; Tsushimi, Takaaki; Kobara, Hideki; Nishiyama, Noriko; Fujihara, Shintaro; Matsunaga, Tae; Ayaki, Maki; Chiyo, Taiga; Masaki, Tsutomu

    2015-01-01

    As numerous reports were published regarding the so-called seatbelt syndrome involved in car crashes, most of them were mentioned about small intestine, duodenum and colon perforations and solid organ bleeding. No reports have been published regarding multiple gastric mucosal tears with intra-gastric wall air leakage with massive bleeding. A 65-year-old woman was admitted after a motor vehicle crash. She vomited massive fresh blood. Gastric mucosal breaks, approximately 5 cm in length, were observed. Computed tomography imaging revealed multiple gastric mucosal breaks. We report a rare case wherein a traffic accident caused a serious condition associated with massive digestive bleeding. PMID:26466695

  16. Prolonged Air Leakage Caused by Mesenchymal Cystic Hamartoma of the Lung

    PubMed Central

    Lee, Young Uk; Lee, Jang Hoon; Baek, Jong Hyun

    2016-01-01

    A 16-year-old girl was transferred to the department of thoracic and cardiovascular surgery because of a spontaneous pneumothorax with prolonged air leakage. Chest computed tomography demonstrated a cystic lesion measuring 2×3 cm and involving the left upper lobe. Left upper lobectomy was performed via video-assisted thoracoscopic surgery. A pathologic examination of the specimen revealed a mesenchymal cystic hamartoma. Despite the rarity of pulmonary mesenchymal cystic hamartoma, it should be considered a potential cause of pneumothorax for patients with a large pulmonary cyst. Further, surgical resection must be considered because serious complications such as hemothorax, hemoptysis, and malignant transformation have been reported. PMID:27525242

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

    SciTech Connect

    Fuller, R.; Harrell, J.

    1996-12-01

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

  18. Evidence of increased levels of space heat consumption and air leakage associated with forced air heating systems in houses in the Pacific Northwest

    SciTech Connect

    Parker, D.S. )

    1989-01-01

    This paper examines energy consumption and air-tightness data from 820 electrically heated houses built since 1980 in the Pacific Northwest. Half of the buildings were energy-efficient structures built to the model conservation standards (MCS) developed in the region. The rest of the sample were conventional new houses intended to be representative of current building practices. The houses were monitored for a period of one year with the structures audited to determine insulation levels and occupancy characteristics. In the analysis of the monitored data we found that heating system type plays a large role in determining the relative efficiency of electrically heated houses. Residences with electric forced-air heating systems used an average of 1.40 kWh/ft{sup 2} (15.1 kWh/m{sup 2}) more space heating energy than those without them. We also discovered through the use of fan pressurization and perfluorocarbon tracer gas tests (PFT) that houses with forced-air systems exhibited substantially higher level of air leakage. The tracer gas tests indicated an average of 70% higher levels of air change rate in the control houses with forced-air space heat as opposed to baseboard systems.

  19. Affect of Air Leakage into a Thermal-Vacuum Chamber on Helium Refrigeration Heat Load

    NASA Technical Reports Server (NTRS)

    Garcia, Sam; Meagher, Daniel; Linza, Robert; Saheli, Fariborz; Vargas, Gerardo; Lauterbach, John; Reis, Carl; Ganni, Venkatarao (Rao); Homan, Jonathan

    2008-01-01

    NASA s Johnson Space Center (JSC) Building 32 houses two large thermal-vacuum chambers (Chamber A and Chamber B). Within these chambers are liquid nitrogen shrouds to provide a thermal environment and helium panels which operate at 20K to provide cryopumping. Some amount of air leakage into the chambers during tests is inevitable. This causes "air fouling" of the helium panel surfaces due to the components of the air that adhere to the panels. The air fouling causes the emittance of the helium panels to increase during tests. The increase in helium panel emittance increases the heat load on the helium refrigerator that supplies the 20K helium for those panels. Planning for thermal-vacuum tests should account for this increase to make sure that the helium refrigerator capacity will not be exceeded over the duration of a test. During a recent test conducted in Chamber B a known-size air leak was introduced to the chamber. Emittance change of the helium panels and the affect on the helium refrigerator was characterized. A description of the test and the results will be presented.

  20. A review of air exchange rate models for air pollution exposure assessments.

    PubMed

    Breen, Michael S; Schultz, Bradley D; Sohn, Michael D; Long, Thomas; Langstaff, John; Williams, Ronald; Isaacs, Kristin; Meng, Qing Yu; Stallings, Casson; Smith, Luther

    2014-11-01

    A critical aspect of air pollution exposure assessments is estimation of the air exchange rate (AER) for various buildings where people spend their time. The AER, which is the rate of exchange of indoor air with outdoor air, is an important determinant for entry of outdoor air pollutants and for removal of indoor-emitted air pollutants. This paper presents an overview and critical analysis of the scientific literature on empirical and physically based AER models for residential and commercial buildings; the models highlighted here are feasible for exposure assessments as extensive inputs are not required. Models are included for the three types of airflows that can occur across building envelopes: leakage, natural ventilation, and mechanical ventilation. Guidance is provided to select the preferable AER model based on available data, desired temporal resolution, types of airflows, and types of buildings included in the exposure assessment. For exposure assessments with some limited building leakage or AER measurements, strategies are described to reduce AER model uncertainty. This review will facilitate the selection of AER models in support of air pollution exposure assessments. PMID:23715084

  1. Impact of heating and air conditioning system operation and leakage on ventilation and intercompartment transport: studies in unoccupied and occupied Tennessee Valley homes.

    PubMed

    Matthews, T G; Wilson, D L; Thompson, C V; Monar, K P; Dudney, C S

    1990-02-01

    Forced-air heating and air conditioning (HAC) systems caused an average and maximum increase in air infiltration rates of 1.8- and 4.3-fold, respectively, during brief whole-house studies of tracer gas decay in 39 occupied houses. An average increase in air infiltration rate of 0.33 +/- 0.37 h-1 corresponded to an incremental air leak of 240 m3/h, based on approximate house volume. More detailed tracer gas decay studies were performed in basement, kitchen and bedroom locations of six homes with low air infiltration rates (i.e., less than 0.25 h-1). The HAC mixed the indoor air efficiently between measurement sites. HAC operation also caused 1.1- to 3.6-fold increases in air infiltration rates, corresponding to absolute increases of 0.02 to 0.1 h-1. In an unoccupied research house, three-fold increases in average air infiltration rate with HAC operation (i.e., from 0.13 to 0.36 h-1) were reduced to two-fold (i.e., from 0.10 to 0.18 h-1) by sealing the external HAC unit and crawlspace ductwork system. This sealing also resulted in a 30 percent reduction in crawlspace-to-indoor transport rates with the HAC turned on. Blower door tests indicated a less than 20 percent reduction in house leakage area. PMID:2306364

  2. Decreased leakage rate of colonic anastomoses by tachosil coating: an experimental study.

    PubMed

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

    2014-01-01

    Colorectal anastomotic coating has been proposed as a means to lower the leakage rate. Prior to clinical testing, coating materials need thorough experimental evaluation to ensure safety and efficacy. The aim of this study was to evaluate Tachosil as an anastomotic coating agent. Technically insufficient colon anastomoses were created in 80 C57BL/6 mice, and in half of the animals the anastomoses were covered with Tachosil. The animals were examined for clinical signs of anastomotic leakage, and the breaking strength of the anastomoses was evaluated. The number of leakages was reduced by Tachosil coating (10/40 versus 20/40 in controls; P=0.037). However, more cases of large bowel obstruction were found in the Tachosil group (12/40 versus 0/40 in controls; P<0.0005). Breaking strength was comparable between the Tachosil and control groups (0.49 N versus 0.52 N, respectively; P=0.423). Clinical studies are needed to clarify the efficacy of Tachosil anastomotic coating. PMID:25058765

  3. Methane leakage from evolving petroleum systems: Masses, rates and inferences for climate feedback

    NASA Astrophysics Data System (ADS)

    Berbesi, L. A.; di Primio, R.; Anka, Z.; Horsfield, B.; Wilkes, H.

    2014-02-01

    The immense mass of organic carbon contained in sedimentary systems, currently estimated at 1.56×1010 Tg (Des Marais et al., 1992), bears the potential of affecting global climate through the release of thermally or biologically generated methane to the atmosphere. Here we investigate the potential of naturally-occurring gas leakage, controlled by petroleum generation and degradation as a forcing mechanism for climate at geologic time scales. We addressed the potential methane contributions to the atmosphere during the evolution of petroleum systems in two different, petroliferous geological settings: the Western Canada Sedimentary Basin (WCSB) and the Central Graben area of the North Sea. Besides 3D numerical simulation, different types of mass balance and theoretical approaches were applied depending on the data available and the processes taking place in each basin. In the case of the WCSB, we estimate maximum thermogenic methane leakage rates in the order of 10-2-10-3 Tg/yr, and maximum biogenic methane generation rates of 10-2 Tg/yr. In the case of the Central Graben, maximum estimates for thermogenic methane leakage are in the order in 10-3 Tg/yr. Extrapolation of our results to a global scale suggests that, at least as a single process, thermal gas generation in hydrocarbon kitchen areas would not be able to influence climate, although it may contribute to a positive feedback. Conversely, only the sudden release of subsurface methane accumulations, formed over geologic timescales, can possibly allow for petroleum systems to exert an effect on climate.

  4. Effects of walk-by and sash movement on contaminant leakage of air curtain-isolated fume hood.

    PubMed

    Huang, Rong Fung; Chen, Hong Da; Hung, Chien-Hsiung

    2007-12-01

    The effects of the walk-by motion and sash movement on the containment leakage of an air curtain-isolated fume hood were evaluated and compared with the results of a corresponding conventional fume hood. The air curtain was generated by a narrow planar jet issued from the double-layered sash and a suction slot-flow arranged on the floor of the hood just behind the doorsill. The conventional fume hood used for comparison had the major dimensions identical to the air-curtain hood. SF tracer-gas concentrations were released and measured following the prEN 14175-3:2003 protocol to examine the contaminant leakage levels. Experimental results showed that operating the air-curtain hood at the suction velocity above about 6 m/s and jet velocity about 1 m/s could provide drastically high containment performance when compared with the corresponding conventional fume hood operated at the face velocity of 0.5 m/s. The total air flow required for the air-curtain hood operated at 6 m/s suction velocity and 1 m/s jet velocity was about 20% less than that exhausted by the conventional fume hood. If the suction velocity of the air-curtain hood was increased above 8 m/s, the containment leakage during dynamic motions could be reduced to ignorable level (about 10(3) ppm). PMID:18212476

  5. FIELD EVALUATION OF IMPROVED METHODS FOR MEASURING THE AIR LEAKAGE OF DUCT SYSTEMS UNDER NORMAL OPERATING CONDITIONS IN 51 HOMES

    SciTech Connect

    Paul W. Francisco; Larry Palmiter; Erin Kruse; Bob Davis

    2003-10-18

    Duct leakage in forced-air distribution systems has been recognized for years as a major source of energy losses in residential buildings. Unfortunately, the distribution of leakage across homes is far from uniform, and measuring duct leakage under normal operating conditions has proven to be difficult. Recently, two new methods for estimating duct leakage at normal operating conditions have been devised. These are called the nulling test and the Delta-Q test. Small exploratory studies have been done to evaluate these tests, but previously no large-scale study on a broad variety of homes has been performed to determine the accuracy of these new methods in the field against an independent benchmark of leakage. This sort of study is important because it is difficult in a laboratory setting to replicate the range of leakage types found in real homes. This report presents the results of a study on 51 homes to evaluate these new methods relative to an independent benchmark and a method that is currently used. An evaluation of the benchmark procedure found that it worked very well for supply-side leakage measurements, but not as well on the return side. The nulling test was found to perform well, as long as wind effects were minimal. Unfortunately, the time and difficulty of setup can be prohibitive, and it is likely that this method will not be practical for general use by contractors except in homes with no return ducts. The Delta-Q test was found to have a bias resulting in overprediction of the leakage, which qualitatively confirms the results of previous laboratory, simulation, and small-scale field studies. On average the bias was only a few percent of the air handler flow, but in about 20% of the homes the bias was large. A primary flaw with the Delta-Q test is the assumption that the pressure between the ducts and the house remain constant during the test, as this assumption does not hold true. Various modifications to the Delta-Q method were evaluated as

  6. Air kerma rate constants for radionuclides.

    PubMed

    Wasserman, H; Groenewald, W

    1988-01-01

    Conversion to SI units requires that the exposure rate constant which was usually quoted in R.h-1.mCi-1.cm2 be replaced by the air kerma rate constant with units m2.Gy.Bq-1.s-1. The conversion factor is derived and air kerma rate constants for 30 radionuclides used in nuclear medicine and brachytherapy are listed. A table for calculation of air kerma rates for other radionuclides is also given. To calculate absorbed dose to tissue, the air kerma rate has to be multiplied by approximately 1.1. A dose equivalent rate constant is thus listed which allows direct calculation of dose equivalent rate to soft tissue without resorting to exposure rate constants tabulated in the special units R.m2.mCi-1.h-1 which should no longer be used. PMID:3208786

  7. Air Controlman 1 & C: Rate Training Manual.

    ERIC Educational Resources Information Center

    Naval Training Command, Pensacola, FL.

    The manual is designed for use in preparing for advancement within the Navy Air Controlman rating, which designates a professional air traffic controller, unlike the more specialized center or tower controllers. However, minimum qualifications for the rating include completion of the Federal Aviation Administration (FAA) written examination for…

  8. Calculated in-air leakage spectra and power levels for the ANSI standard minimum accident of concern. Final report

    SciTech Connect

    Lee, B.L. Jr.; Dobelbower, M.C.; Tayloe, R.W. Jr.

    1995-07-01

    This document represents Phase I of a two-phase project. The entire project consists of determining a series of minimum accidents of concern and their associated neutron and photon leakage spectra that may be used to determine Criticality Accident Alarm compliance with ANSI/ANS-8.3. The inadvertent assembly of a critical mass of material presents a multitude of unknown quantities. Depending on the particular process, one can make an educated guess as to fissile material. In a gaseous diffusion cascade, this material is assumed to be uranyl fluoride. However, educated assumptions cannot be readily made for the other variables. Phase I of this project is determining a bounding minimum accident of concern and its associated neutron and photon leakage spectra. To determine the composition of the bounding minimum accident of concern, work was done to determine the effects of geometry, moderation level, and enrichment on the leakage spectra of a critical assembly. The minimum accident of concern is defined as the accident that may be assumed to deliver the equivalent of an absorbed dose in free air of 20 rad at a distance of 2 meters from the reacting material within 60 seconds. To determine this dose, an analyst makes an assumption and choose an appropriate flux to dose response function. The power level required of a critical assembly to constitute a minimum accident of concern depends heavily on the response function chosen. The first step in determining the leakage spectra was to attempt to isolate the effects of geometry, after which all calculations were conducted on critical spheres. The moderation level and enrichment of the spheres were varied and their leakage spectra calculated. These spectra were then multiplied by three different response functions: the Henderson Flux to Dose conversion factors, the ICRU 44 Kerma in Air, and the MCNP Heating Detector. The power level required to produce a minimum accident of concern was then calculated for each combination.

  9. Development of a Mathematical Air-Leakage Model from MeasuredData

    SciTech Connect

    McWilliams, Jennifer; Jung, Melanie

    2006-05-01

    A statistical model was developed to relate residential building shell leakage to building characteristics such as building height, floor area, floor leakage, duct leakage, and year built or the age of the house. Statistical regression techniques were used to determine which of the potential building characteristics best described the data. Seven preliminary regressions were performed to investigate the influence of each variable. The results of the eighth and last multivariable linear regression form the predictive model. The major factors that influence the tightness of a residential building are participation in an energy efficiency program (40% tighter than ordinary homes), having low-income occupants (145% leakier than ordinary) and the age of a house (1% increase in Normalized Leakage per year). This predictive model may be applied to data within the range of the data that was used to develop the model.

  10. SU-E-T-628: Effect of Dose Rate and Leakage Correction for Dosimetric Leaf Gap Measurement

    SciTech Connect

    Feng, W; Chu, A; Chi, Y; Hu, J

    2014-06-15

    Purpose: To study the dose rate response of Mapcheck and quantify/correct dose rate/leakage effect on IMRT QA. Evaluate the dose rate/leakage effect on dosimetric leaf gap (DLG) measurement. Methods: Varian Truebeam Linac with HD120 MLC was used for all measurement, it is capable to adjust dose rate from 600MU/min to 5MU/min. Fluke Advanced Therapy Doisemter and PTW 30013 Farmer chamber for chamber measurement; SunNuclear Mapcheck2 with 5cm total buildup for diode measurement. DLG was measured with both chamber and diode.Diode response was measured by varies dose rate, while fixed mapcheck setup and total MU. MLC Leakage was measured with both chamber and diode. Mapcheck measurement was saved as movie file (mcm file), which include measurement updated every 50mSec. The difference between intervals can be converted to dose and dose rate and leakage response correction can be applied to them. Results: DLG measurement results with chamber and diode were showed as follows, the DLG value is 0.36 vs. 0.24mm respectively. Diode dose rate response drops from 100% at 600MU/min to 95.5% at 5MU/min as follows. MLC Leakage measured with diode is 1.021%, which is 9% smaller than 1.112% from chamber measurement. By apply the dose rate and leakage correction, the residue error reduced 2/3. Conclusions: Diode has lower response at lower dose rate, as low as 4.5% for 5MU/min; diode has lower energy response for low energy too, 5% lower for Co-60 than 6MV. It partially explains the leakage difference of 9% between chamber and diode. Lower DLG with diode is because of the lower response at narrower gap, in Eclipse however DLG need to increase to makeup lower response, which is over correction for chamber though. Correction can reduce error by 2/3, the rest 1/3 can be corrected by scatter effect, which is under study.

  11. Comparison of hydraulic and chemical methods for determining hydraulic conductivity and leakage rates in argillaceous aquitards

    NASA Astrophysics Data System (ADS)

    Batlle-Aguilar, Jordi; Cook, Peter G.; Harrington, Glenn A.

    2016-01-01

    The capacity of argillaceous aquitards to effectively separate fresh water aquifers from lower quality waters has been widely studied for several decades using both hydraulic and chemical methods. Hydraulic methods, namely laboratory, field and regional groundwater flow modelling, are used to estimate hydraulic conductivity (K), whereas chemical methods, namely aquitard porewater and aquifer groundwater chemistry, are used to estimate either leakage rates or porewater velocity (V). We reviewed a total of 40 formations where either K or V (or both) have been estimated. Typical vertical hydraulic conductivity (KZ) values in argillaceous materials estimated using hydraulic methods are 10-12-10-9 m s-1. Usual V values, estimated using chemical methods, ranges between 0.01 and 1 mm y-1, although the range is as wide as 10-4-103 mm y-1, when inferred from hydraulic KZ measurements. Based on a Péclet number of 1, we calculated the lower limits of porewater velocity that can be reliably identified for different tracers, in most cases ranging from <1 mm y-1 for 2H, 18O and Cl- to >100 mm y-1 for temperature. Despite the limited number of sites where both methods were applied, comparison between hydraulic and chemical-derived values showed a reasonable correlation, although the range of KZ and V estimated using hydraulic methods is larger than that obtained using chemical methods. Methods applied to the whole aquitard thickness (some field hydraulic methods, regional groundwater flow modelling, aquitard porewater and aquifer chemistry) consistently result in lower KZ values, most probably indicating the presence of very low KZ layers within the aquitard, likely to be missed while using field hydraulic methods that test only a section of the entire thickness. KZ was observed to decrease with depth, presumably due to an increase in consolidation resulting in loss of porosity and smaller aperture of fractures and joints. Multi-disciplinary studies involving the use of

  12. Air exchange rates in new energy-efficient manufactured housing

    SciTech Connect

    Hadley, D.; Bailey, S.

    1990-10-01

    During the 1989--1990 heating season, Pacific Northwest Laboratory, for the Bonneville Power Administration, measured the ventilation characteristics of 139 newly constructed energy-efficient manufactured homes and a control sample of 35 newer manufactured homes. A standard door fan pressurization technique was used to estimate shell leakiness, and a passive perfluorocarbon tracer technique was used to estimate overall air exchange rates. A measurement of the designated whole-house exhaust system flow rate was taken as well as an occupant and structure survey. The energy-efficient manufactured homes have very low air exchange rates, significantly lower than either existing manufactured homes or site-built homes. The standard deviation of the effective leakage area for this sample of homes is small (25% to 30% of the mean), indicating that the leakiness of manufactured housing stock can be confidently characterized by the mean value. There is some indication of increased ventilation due to the energy-efficient whole-house ventilation specification, but not directly related to the operation of the whole-house system. The mechanical systems as installed and operated do not provide the intended ventilation; consequently indoor air quality could possibly be adversely impacted and moisture/condensation in the living space is a potential problem. 6 refs., 6 figs., 5 tabs.

  13. Decreased Rate of CSF Leakage Associated with Complete Reconstruction of Suboccipital Cranial Defects

    PubMed Central

    Stoker, Michael A.; Forbes, Jonathan A.; Hanif, Rimal; Cooper, Calvin; Nian, Hui; Konrad, Peter E.; Neimat, Joseph S.

    2012-01-01

    Background Cerebrospinal fluid (CSF) leakage represents a major source of morbidity following microvascular decompression (MVD) surgery. The objective of this study was to retrospectively assess whether complete versus incomplete reconstruction of the suboccipital cranial defect influences the incidence of CSF leakage following MVD. Methods We reviewed the charts of 100 patients who consecutively underwent MVD for trigeminal neuralgia by two attending neurosurgeons between July 2004 and April 2010. Operative variables including incomplete or complete calvarial reconstruction, primary dural closure or dural closure with adjunct, and use of lumbar drainage were recorded. The effect of complete calvarial reconstruction on the incidence of postoperative CSF leakage was examined using a multivariate logistic regression model. Results Of the 36 patients whose wound closure was reconstructed with a complete cranioplasty, 2 (5.6%) patients experienced a postoperative CSF leak. Of the 64 patients whose wound closure was augmented with an incomplete cranioplasty, 15 (23.4%) experienced a postoperative CSF leak. There was suggestive but inconclusive evidence that the risk of CSF leakage following MVD was smaller with complete reconstruction of calvarial defect than with incomplete reconstruction (two-sided p value = 0.059), after accounting for age, dural closure method, use of lumbar drainage, and previous MVD. Conclusion Complete reconstruction of the suboccipital cranial defect decreases the risk of CSF leakage. PMID:23905005

  14. Pressurized air injection in an axial hydro-turbine model for the mitigation of tip leakage cavitation

    NASA Astrophysics Data System (ADS)

    Rivetti, A.; Angulo, M.; Lucino, C.; Liscia, S.

    2015-12-01

    Tip leakage vortex cavitation in axial hydro-turbines may cause erosion, noise and vibration. Damage due to cavitation can be found at the tip of the runner blades on the low pressure side and the discharge ring. In some cases, the erosion follows an oscillatory pattern that is related to the number of guide vanes. That might suggest that a relationship exists between the flow through the guide vanes and the tip vortex cavitating core that induces this kind of erosion. On the other hand, it is known that air injection has a beneficial effect on reducing the damage by cavitation. In this paper, a methodology to identify the interaction between guide vanes and tip vortex cavitation is presented and the effect of air injection in reducing this particular kind of erosion was studied over a range of operating conditions on a Kaplan scale model. It was found that air injection, at the expense of slightly reducing the efficiency of the turbine, mitigates the erosive potential of tip leakage cavitation, attenuates the interaction between the flow through the guide vanes and the tip vortex and decreases the level of vibration of the structural components.

  15. Transanal drainage tube reduces rate and severity of anastomotic leakage in patients with colorectal anastomosis: A case controlled study

    PubMed Central

    Brandl, A.; Czipin, S.; Mittermair, R.; Weiss, S.; Pratschke, J.; Kafka-Ritsch, R.

    2016-01-01

    Background and aims The aim of this study was to investigate the clinical usefulness of the placement of a transanal drainage tube to prevent anastomotic leakage in colorectal anastomoses. Material and methods This single-center retrospective trial included all patients treated with surgery for benign or malign colorectal disease between January 2009 and December 2012. The transanal drainage tube was immediately placed after colorectal anastomosis until day five and was routinely used since 2010. Patients treated with a transanal drainage tube were compared with the control group. Statistical analysis was performed using Fisher's exact or Chi-square tests for group comparison and a linear regression model for multivariate analysis. Results This study included 242 patients (46% female; median age 63 years; range 18–93); 34% of the patients underwent a laparoscopic procedure, and 57% of the patients received a placement of a transanal drainage tube. Anastomotic leakage occurred in 19 patients (7.9%). Univariate analysis showed a higher rate of anastomotic leakage in patients with an ASA score 4 (p = 0.02) and a lower rate in patients with transanal drainage placement (3.6% vs. 13.6%; p = 0.007). The grading of the complication of anastomotic leakage was reduced with transanal drainage (e.g., Dindo ≧ 3b: 20.0% vs. 92.9%; p = 0.006), and the hospital stay was shortened (17.6 ± 12.5 vs. 22.1 ± 17.6 days; p = 0.02). Multivariate analysis revealed that transanal drainage was the only significant factor (HR = −2.90; −0.168 to −0.032; p = 0.007) affecting anastomotic leakage. Conclusions Placement of a transanal drainage tube in patients with colorectal anastomoses is a safe and simple technique to perform and reduces anastomotic leakage, the severity of the complication and hospital stay. PMID:27158483

  16. Impact of Air Leakage on the Thermal and Moisture Performance of the Building Envelope

    SciTech Connect

    Karagiozis, A

    2001-08-15

    The air tightness of building envelopes systems is critical to the performance of a building. Uncontrolled airflow movements can cause moisture-induced damage by transporting large amounts of moisture, and may also impact occupant health and safety, sound control, fire control and energy efficiency. Building envelopes are often designed to control airflow by providing a resistance to the bulk flow. Implementation of air barrier systems to restrict airflow is commonly used to reduce the quantity of airflow movement between the exterior and interior environments through the wall. This paper presents a preliminary assessment of the influence of airflow on the moisture performance of a residential building envelope system. The combined heat, air and moisture (hygrothermal) transport in a selected wall is numerically investigated. Vapor diffusion, liquid transport and temperature dependent sorption isotherms are included in the investigation.

  17. 40 CFR 86.1867-12 - CO2 credits for reducing leakage of air conditioning refrigerant.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... VEHICLES AND ENGINES General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1867-12 CO2 credits... passenger automobiles and/or light trucks. Credits shall be calculated according to this section for...

  18. 40 CFR 86.1867-12 - CO2 credits for reducing leakage of air conditioning refrigerant.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty Vehicles § 86.1867-12... of their passenger automobiles and/or light trucks. Credits shall be calculated according to...

  19. Strength characteristics and air-leakage determinations for alternative mine seal designs. Report of Investigations/1993

    SciTech Connect

    Weiss, E.S.; Greninger, N.B.; Stephan, C.R.; Lipscomb, J.R.

    1993-01-01

    During the normal course of underground coal mining, it sometimes becomes necessary to seal off abandoned areas to eliminate the need to ventilate them. Seals also are used to isolate fire zones or areas susceptible to spontaneous combustion. The objective of the research is to determine whether seals constructed from various materials and designs can withstand a 20-psig methane-air explosion without losing their structural integrity.

  20. Review of Air Exchange Rate Models for Air Pollution Exposure Assessments

    EPA Science Inventory

    A critical aspect of air pollution exposure assessments is estimation of the air exchange rate (AER) for various buildings, where people spend their time. The AER, which is rate the exchange of indoor air with outdoor air, is an important determinant for entry of outdoor air pol...

  1. 49 CFR 229.59 - Leakage.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Leakage from the main air reservoir and related piping may not exceed an average of 3 pounds per square... shall remain applied at least 5 minutes. (d) Leakage from control air reservoir, related piping,...

  2. 49 CFR 229.59 - Leakage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Leakage from the main air reservoir and related piping may not exceed an average of 3 pounds per square... shall remain applied at least 5 minutes. (d) Leakage from control air reservoir, related piping,...

  3. Reduction of air in-leakage and flue gas by-passing in the penthouse of Duke Power-Marshall Unit No. 4

    SciTech Connect

    Campbell, R.; Rush, T.

    1995-12-31

    After a year of operation, the penthouse was inspected and found to be {open_quotes}lightly dusted{close_quotes} with barely sufficient accumulation to show footprints. This is contrasted with previous five foot deep ash dunes. The savings in maintenance repairs are estimated at $65,000 for vacuuming that was not required, and $80,000 in maintenance personnel weld repairs. The history of repairs was such that vacuuming and weld repair costs were predictable, and before the IOSMEMBRANE{reg_sign} installation, always expected as recurring maintenance costs. The heat rate improvement of reducing air in-leakage is well known, and significant. The principal quantified savings are in reduced maintenance costs, more expedient repairs (reduced cool down time for repairs in the penthouse), and safety. The heat rate improvements, though not quantified yet, are expected to be significant. The success of the ISOMEMBRANE{reg_sign} on Unit No. 4 has resulted in similar plans for Unit No. 3 and other units in the Duke Power system.

  4. A conversion method of air kerma from the primary, scatter, and leakage radiations to effective dose for calculating x-ray shielding barriers in mammography

    SciTech Connect

    Kharrati, Hedi

    2005-05-01

    In this study, a new approach has been introduced for derivation of the effective dose from air kerma to calculate shielding requirements in mammography facilities. This new approach has been used to compute the conversion coefficients relating air kerma to the effective dose for the mammography reference beam series of the Netherlands Metrology Institute Van Swinden Laboratorium, National Institute of Standards and Technology, and International Atomic Energy Agency laboratories. The results show that, in all cases, the effective dose in mammography energy range is less than 25% of the incident air kerma for the primary and the scatter radiations and does not exceed 75% for the leakage radiation.

  5. Reducing Uncertainty for the DeltaQ Duct Leakage Test

    SciTech Connect

    Walker, Iain S.; Sherman, Max H.; Dickerhoff, Darryl J.

    2004-05-01

    The thermal distribution system couples the HVAC components to the building envelope, and shares many properties of the buildings envelope including moisture, conduction and most especially air leakage performance. Duct leakage has a strong influence on air flow rates through building envelopes (usually resulting in much greater flows than those due to natural infiltration) because unbalanced duct air flows and leaks result in building pressurization and depressurization. As a tool to estimate this effect, the DeltaQ duct leakage test has been developed over the past several years as an improvement to existing duct pressurization tests. It focuses on measuring the air leakage flows to outside at operating conditions that are required for envelope infiltration impacts and energy loss calculations for duct systems. The DeltaQ test builds on the standard envelope tightness blower door measurement techniques by repeating the tests with the system air handler off and on. The DeltaQ test requires several assumptions to be made about duct leakage and its interaction with the duct system and building envelope in order to convert the blower door results into duct leakage at system operating conditions. This study examined improvements to the DeltaQ test that account for some of these assumptions using a duct system and building envelope in a test laboratory. The laboratory measurements used a purpose-built test chamber coupled to a duct system typical of forced air systems in US homes. Special duct leaks with controlled air-flow were designed and installed into an airtight duct system. This test apparatus allowed the systematic variation of the duct and envelope leakage and accurate measurement of the duct leakage flows for comparison to DeltaQ test results. This paper will discuss the laboratory test apparatus design, construction and operation, the various analysis techniques applied to the calculation procedure and present estimates of uncertainty in measured duct

  6. IMPACT OF HEATING AND AIR CONDITIONING SYSTEM OPERATION AND LEAKAGE ON VENTILATION AND INTERCOMPARTMENT TRANSPORT: STUDIES IN UNOCCUPIED AND OCCUPIED TENNESSEE VALLEY HOMES

    EPA Science Inventory

    Forced-air heating and air conditioning (HAC) systems caused an average and maximum increase in air infiltration rates of 1.8- and 4.3-fold, respectively, during brief whole-house studies of tracer gas decay In 39 occupied houses. An average Increase in air infiltration rate of 0...

  7. Current Problems and Issues in Air Freight Rates

    NASA Technical Reports Server (NTRS)

    Stout, A. R.

    1972-01-01

    Actions of the Civil Aeronautics Board in determining air freight rates are discussed. The tariff filings by domestic airlines for making basic changes in domestic fares and rates are reported. The roles of the carriers and the Civil Aeronautics Board in establishing freight rates are defined. Specific examples of areas of controversy in establishing freight rates are included. Methods for improving the air cargo and freight rate situation are proposed.

  8. Quantifying canal leakage rates using a mass-balance approach and heat-based hydraulic conductivity estimates in selected irrigation canals, western Nebraska, 2007 through 2009

    USGS Publications Warehouse

    Hobza, Christopher M.; Andersen, Michael J.

    2010-01-01

    The water supply in areas of the North Platte River Basin in the Nebraska Panhandle has been designated as fully appropriated or overappropriated by the Nebraska Department of Natural Resources (NDNR). Enacted legislation (Legislative Bill 962) requires the North Platte Natural Resources District (NPNRD) and the NDNR to develop an Integrated Management Plan (IMP) to balance groundwater and surface-water supply and demand in the NPNRD. A clear understanding of the groundwater and surface-water systems is critical for the development of a successful IMP. The primary source of groundwater recharge in parts of the NPNRD is from irrigation canal leakage. Because canal leakage constitutes a large part of the hydrologic budget, spatially distributing canal leakage to the groundwater system is important to any management strategy. Surface geophysical data collected along selected reaches of irrigation canals has allowed for the spatial distribution of leakage on a relative basis; however, the actual magnitude of leakage remains poorly defined. To address this need, the U.S. Geological Survey, in cooperation with the NPNRD, established streamflow-gaging stations at upstream and downstream ends from two selected canal reaches to allow a mass-balance approach to be used to calculate daily leakage rates. Water-level and sediment temperature data were collected and simulated at three temperature monitoring sites to allow the use of heat as a tracer to estimate the hydraulic conductivity of canal bed sediment. Canal-leakage rates were estimated by applying Darcy's Law to modeled vertical hydraulic conductivity and either the estimated or measured hydraulic gradient. This approach will improve the understanding of the spatial and temporal variability of canal leakage in varying geologic settings identified in capacitively coupled resistivity surveys. The high-leakage potential study reach of the Tri-State Canal had two streamflow-gaging stations and two temperature monitoring

  9. Air velocity distributions from a variable-rate air-assisted sprayer for tree applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A capability that implements tree structure to control liquid and air flow rates is the preferential design in the development of variable-rate orchard and nursery sprayers. Air jet velocity distributions from an air assisted, five-port sprayer which was under the development to achieve variable-rat...

  10. RESIDENTIAL AIR EXCHANGE RATES FOR USE IN INDOOR AIR AND EXPOSURE MODELING STUDIES

    EPA Science Inventory

    Data on air exchange rates are important inputs to indoor air quality models. ndoor air models, in turn, are incorporated into the structure of total human exposure models. ragmentary data on residential ventilation rates are available in various governmental reports, journal art...

  11. Using Sulfur Hexafluoride to Quantify the Gas Leakage Rate within the Landscape Evolution Observatory (LEO) and the Diffusion Coefficient of the Crushed Basalt

    NASA Astrophysics Data System (ADS)

    Barta, J.; Costa, M.; Van Haren, J. L. M.; Pangle, L. A.; Troch, P. A. A.

    2014-12-01

    In order to understand the biological processes taking place on an experimental hillslope with vegetation, it is important to know the amount of gasses such as oxygen and carbon dioxide being produced and consumed. When studying the gas exchange rates in a closed system like the Landscape Evolution Observatory (LEO), one must take into account gas that is being lost or gained from other sources. Aside from biogeochemical processes, gas concentrations in the LEO atmosphere may change due to leakage to the outside environment and diffusion into the soil. To quantify these fluxes, two constants must be determined experimentally: the gas leakage constant L and the coefficient of diffusion for the hillslope soil. To accomplish this, a tracer gas, sulfur hexafluoride, was injected into the sealed east bay chamber and syringes were used to take samples periodically from the airspace and from the hillslope soil. The relative sulfur hexafluoride concentrations were then analyzed with a SRI 8610c gas chromatograph. By analyzing both the the airspace concentration decay as well as the concentration in the soil, the chamber's leakage constant was determined to be and the soil diffusion coefficient was also determined. Once these values are experimentally quantified, they can be used in equations to quantify the rate of gas leakage and soil diffusion of more important gases such as carbon dioxide and oxygen.

  12. Hygrothermal performance of EIFS-clad walls: Effect of vapor diffusion and air leakage on the drying of construction moisture [Exterior Insulation and Finish Systems

    SciTech Connect

    Karagiozis, A.N.; Salonvaara, M.H.

    1999-07-01

    Hydrothermal performance describes the response of the material layers that make up the wall to thermal and moisture loads. Modeling can be applied to determine the drying and wetting potential of walls with various initial construction moisture loads and to test alternative innovations. This paper investigates the drying performance of a particular barrier EIFS clad wall as a function of vapor diffusion control with a specific air leakage path. This investigation was conducted with constant interior temperature and relative humidity. The LATENITE model, developed at NRD, is employed in the investigation. This advanced hydrothermal model can incorporate system and sub-system performances by introducing simulated defects and wall system details derived from laboratory and field measurements. Moisture loads available to the EIFS structure originating either from the interior, the exterior or from initial construction moisture can be included. In this paper the authors present a study to determine the drying potential of a barrier EIFS clad wall for the climate of Wilmington, NC. This climate is characterized by the ASHRAE Handbook of Fundamentals as being mixed. The effect of drying and wetting by airflow was investigated by introducing airflow paths. Hydrothermal performance with three different vapor diffusion control strategies and two air leakage conditions was simulated for a period of one year. Initial oriented strand board (OSB) moisture content was assumed to be very high. The influence of rain water, solar radiation and air movement within the cavity was included in the analysis.

  13. Nonlinear analysis of orbital motion of a rotor subject to leakage air flow through an interlocking seal

    NASA Astrophysics Data System (ADS)

    Wang, W. Z.; Liu, Y. Z.; Meng, G.; Jiang, P. N.

    2009-07-01

    A nonlinear mathematical model for orbital motion of the rotor under the influence of leakage flow through a labyrinth seal was established in the present study. An interlocking seal was chosen for study. The rotor-seal system was modeled as a Jeffcot rotor subject to aerodynamic forcing induced by the leakage flow. Particular attention was placed on the serpentine flow path by spatially separating the aerodynamic force on the rotor surface into two parts, e.g., the seal clearance and the cavity volume. Spatio-temporal variation of the aerodynamic force on the rotor surface in the coverage of the seal clearance and the cavity volume was delineated by using the Muzynska model and perturbation analysis, respectively. The governing equation of rotor dynamics, which was incorporated with the aerodynamic force integrated over all seal clearances and cavity volumes, was solved by using the fourth-order Runge-Kutta method to obtain the orbit of the whirling rotor. Stability of the rotating rotor was inspected using the Liapunov first method. The results convincingly demonstrate that the destabilization speed of the rotor was reduced due to the aerodynamic force induced by the leakage flow through the interlocking seal. The nonlinear analysis method proposed in the present study is readily applied to dynamics of various rotor-seal systems with labyrinth seals.

  14. Semi-analytical solution for pressure change and leakage rate through aquifer leaks or fractures considering both Darcy and non-Darcy phenomena

    NASA Astrophysics Data System (ADS)

    Islam, J.; Zhan, H.

    2013-12-01

    Study of potential leakage of hazardous liquid waste into deep aquifer or abandoned wells is very important research work in recent days. CO2 sequestration into the brine media is not an exception of that. The saline aquifer is always overlain by a leaky aquitard or seal which may allow the migration of the injected CO2 or any kind of hazardous liquid waste to the upper aquifer through some leaks or fractures. The scope of study includes how the migration through the seal or aquitard causes the pressure change in the upper aquifer because of that injection into the target storage aquifer. Such pressure change is used to infer the leakage pathway location and characteristics of the leak or fractures. In this complex issue both Darcian and non-Darcian flow has been taken care of combindly. The Izbash equation has been used to describe the non-Darcian flow in the aquifer. A semi-analytical solution is obtained in Laplace domain and finally it has been solved numerically. Afterwards different parameters have been evaluated (leak or fracture size, injection rate, conductivity) to see how they directly affect the upper aquifer pressure and leakage rate independently.

  15. Position paper -- Tank ventilation system design air flow rates

    SciTech Connect

    Goolsby, G.K.

    1995-01-04

    The purpose of this paper is to document a project position on required ventilation system design air flow rates for the waste storage tanks currently being designed by project W-236A, the Multi-Function Waste Tank Facility (MWTF). The Title 1 design primary tank heat removal system consists of two systems: a primary tank vapor space ventilation system; and an annulus ventilation system. At the conclusion of Title 1 design, air flow rates for the primary and annulus ventilation systems were 960 scfm and 4,400 scfm, respectively, per tank. These design flow rates were capable of removing 1,250,000 Btu/hr from each tank. However, recently completed and ongoing studies have resulted in a design change to reduce the extreme case heat load to 700,000 Btu/hr. This revision of the extreme case heat load, coupled with results of scale model evaporative testing performed by WHC Thermal Hydraulics, allow for a reduction of the design air flow rates for both primary and annulus ventilation systems. Based on the preceding discussion, ICF Kaiser Hanford Co. concludes that the design should incorporate the following design air flow rates: Primary ventilation system--500 scfm maximum and Annulus ventilation system--1,100 scfm maximum. In addition, the minimum air flow rates in the primary and annulus ventilation systems will be investigated during Title 2 design. The results of the Title 2 investigation will determine the range of available temperature control using variable air flows to both ventilation systems.

  16. Predicting Residential Air Exchange Rates from Questionnaires and Meteorology: Model Evaluation in Central North Carolina

    PubMed Central

    2010-01-01

    A critical aspect of air pollution exposure models is the estimation of the air exchange rate (AER) of individual homes, where people spend most of their time. The AER, which is the airflow into and out of a building, is a primary mechanism for entry of outdoor air pollutants and removal of indoor source emissions. The mechanistic Lawrence Berkeley Laboratory (LBL) AER model was linked to a leakage area model to predict AER from questionnaires and meteorology. The LBL model was also extended to include natural ventilation (LBLX). Using literature-reported parameter values, AER predictions from LBL and LBLX models were compared to data from 642 daily AER measurements across 31 detached homes in central North Carolina, with corresponding questionnaires and meteorological observations. Data was collected on seven consecutive days during each of four consecutive seasons. For the individual model-predicted and measured AER, the median absolute difference was 43% (0.17 h−1) and 40% (0.17 h−1) for the LBL and LBLX models, respectively. Additionally, a literature-reported empirical scale factor (SF) AER model was evaluated, which showed a median absolute difference of 50% (0.25 h−1). The capability of the LBL, LBLX, and SF models could help reduce the AER uncertainty in air pollution exposure models used to develop exposure metrics for health studies. PMID:21069949

  17. Greenhouse Gas Growth Rates from AIRS Hyperspectral Radiance Time Series

    NASA Astrophysics Data System (ADS)

    Strow, L. L.; Desouza-Machado, S. G.; Hannon, S.; Imbiriba, B.; Schou, P.

    2009-12-01

    The AIRS seven year hyperspectral radiance record provides an ideal platform for measurings growth rates of infrared active minor gases, especially carbon dioxide and methane. The largest changes in CLARREO radiances will likely be due to increasing carbon dioxide and other greenhouse gases. We have produced a 5+ year record of almost cloud-free AIRS radiances, from which we have derived the radiance anomaly and linear time rate of change. The source of these radiances are the L1b radiances corrected for small frequency drifts. Growth rates of carbon dioxide, nitrous oxide, methane, ozone, and CFC11 are simultaneously derived from zonal averages of these radiance rates for tropics, and mid-latitude northern and southern hemispheres. The effective linear rate of change of ~5 layers of water vapor and temperature, plus the surface temperature are also simultaneously derived with the minor gas rates. No model data or prior is needed and more than 1000 channels are used in the fit. Sampling issues may preclude the use of the mid-latitude temperature and water vapor rates for climate analysis, but possibly not for the tropics. The resulting greenhouse gas growth rates agree very well with in-situ measurements, which suggests high radiometric stability for AIRS. Radiance intercomparisons for climate analysis between IASI and AIRS will also be presented.

  18. Relationship between air exchange rate and indoor VOC levels

    SciTech Connect

    Otson, R.; Williams, D.T.; Fellin, P.

    1998-12-31

    It is often assumed that the air quality is better in leaky than in airtight buildings. To test this anecdotal hypothesis, data from two Canadian surveys were examined. Indoor measurements of 28 volatile organic compounds (VOCs) were made by means of a passive sampling method during the 24 to 48 h study periods in both studies, and air exchange rates were determined by the perfluorocarbon tracer approach. The air exchange rates ranged between about 0.1 to 2.5 air changes per hour in 54 test homes in the Greater Toronto Area (GTA). Other information on building age and construction, renovation activities and occupant activities that potentially influenced indoor VOC concentrations in the homes was collected by means of a questionnaire. The statistical relationships between the concentrations of VOCs and air exchange were determined. Correlation coefficients between the airborne concentrations of each VOC and the air exchange rates for the homes were all < 0.1 indicating that the relationship between the air exchange and indoor VOC concentrations is tenuous. Since the questionnaire responses did not provide quantitative estimates of indoor emissions, a quantitative correlation between responses and indoor concentrations could not be established nor was a consistent pattern evident between these responses and the occurrence of high indoor concentrations. The lack of definitive quantitative relationships is not surprising considering the complexity of indoor environments, the lack of a detailed inventory of indoor sources and their emission rates and a lack of information or understanding of indoor sinks. The findings, on the effect of air exchange rates and the value of questionnaires in studies on indoor VOCs are consistent with findings in other similar studies.

  19. Residential air exchange rates for use in indoor air and exposure modeling studies.

    PubMed

    Pandian, M D; Ott, W R; Behar, J V

    1993-01-01

    Data on air exchange rates are important inputs to indoor air quality models. Indoor air models, in turn, are incorporated into the structure of total human exposure models. Fragmentary data on residential ventilation rates are available in various governmental reports, journal articles, and contractor reports. Most of the published papers present data on only a few homes to answer very specialized questions, and none of these publications summarize the ventilation rates of a large population of homes across the United States. Brookhaven National Laboratory (BNL) has conducted more than 4000 residential perfluorocarbon tracer (PFT) measurements and brought them together into a large data base from about 100 studies in the United States and elsewhere. This paper analyzes the BNL PFT data base to generate frequency distributions and summary statistics for different regions of the United States, different seasons, and different levels within the homes. The data analyses suggest that residential ventilation rates are similar in the northeastern and northwestern states but higher in the southwestern states. Winter and fall ventilation rates are similar, but the rates are slightly higher in spring, and much higher in summer. Multi-level residences have higher air exchange rates than single-level residences. Although the BNL data are not a representative sample of homes in the United States, these analyses give insight into the range of air exchange rates found in the United States under a great variety of conditions and are intended for use by developers of models of indoor air quality and total human exposure. PMID:8173341

  20. Flow and leakage characteristics of a sashless inclined air-curtain (sIAC) fume hood containing tall pollutant-generation tanks.

    PubMed

    Chen, Jia-Kun; Huang, Rong Fung; Hung, Wei-Lun

    2013-01-01

    In many fume hood applications, pollutant-generation devices are tall. Human operators of a fume hood must stand close to the front of the hood and lift up their hands to reach the top opening of the tall tank. In this situation, it is inconvenient to access the conventional hood because the sash acts as a barrier. Also, the bluff-body wake in front of the operator's chest causes a problem. By using laser-assisted smoke flow visualization and tracer-gas test methods, the present study examines a sashless inclined air-curtain (sIAC) fume hood for tall pollutant-generation tanks, with a mannequin standing in front of the hood face. The configuration of the sIAC fume hood, which had the important element of a backward-inclined push-pull air curtain, was different from conventional configurations. Depending on suction velocity, the backward-inclined air curtain had three characteristic modes: straight, concave, and attachment. A large recirculation bubble covering the area--from the hood ceiling to the work surface--was formed behind the inclined air curtain in the straight and concave modes. In the attachment mode, the inclined air curtain was attached to the rear wall of the hood, about 50 cm from the hood ceiling, and bifurcated into up and down streams. Releasing the pollutants at an altitude above where the inclined air curtain was attached caused the suction slot to directly draw up the pollutants. Releasing pollutants in the rear recirculation bubble created a risk of pollutants' leaking from the hood face. The tracer-gas (SF6) test results showed that operating the sIAC hood in the attachment mode, with the pollutants being released high above the critical altitude, could guarantee almost no leakage, even though a mannequin was standing in front of the sashless hood face. PMID:24195536

  1. Measuring Outdoor Air Intake Rates into Existing Building

    SciTech Connect

    Fisk, William; Sullivan, Douglas; Cohen, Sebastian; Han, Hwataik

    2009-04-16

    Practical and accurate technologies are needed for continuously measuring and controlling outdoor air (OA) intake rates in commercial building heating, ventilating, and air conditioning (HVAC) systems. This project evaluated two new measurement approaches. Laboratory experiments determined that OA flow rates were measurable with errors generally less than 10 percent using electronic air velocity probes installed between OA intake louver blades or at the outlet face of louvers. High accuracy was maintained with OA flow rates as low as 15 percent of the maximum for the louvers. Thus, with this measurement approach HVAC systems do not need separate OA intakes for minimum OA supply. System calibration parameters are required for each unique combination of louver type and velocity sensor location but calibrations are not necessary for each system installation. The research also determined that the accuracy of measuring OA flow rates with velocity probes located in the duct downstream of the intake louver was not improved by installing honeycomb airflow straighteners upstream of the probes. Errors varied with type of upstream louver, were as high as 100 percent, and were often greater than 25 percent. In conclusion, use of electronic air velocity probes between the blades of OA intake louvers or at the outlet face of louvers is a highly promising means of accurately measuring rates of OA flow into HVAC systems. The use of electronic velocity probes downstream of airflow straighteners is less promising, at least with the relatively small OA HVAC inlet systems employed in this research.

  2. High Lapse Rates in AIRS Retrieved Temperatures in Cold Air Outbreaks

    NASA Technical Reports Server (NTRS)

    Fetzer, Eric J.; Kahn, Brian; Olsen, Edward T.; Fishbein, Evan

    2004-01-01

    The Atmospheric Infrared Sounder (AIRS) experiment, on NASA's Aqua spacecraft, uses a combination of infrared and microwave observations to retrieve cloud and surface properties, plus temperature and water vapor profiles comparable to radiosondes throughout the troposphere, for cloud cover up to 70%. The high spectral resolution of AIRS provides sensitivity to important information about the near-surface atmosphere and underlying surface. A preliminary analysis of AIRS temperature retrievals taken during January 2003 reveals extensive areas of superadiabatic lapse rates in the lowest kilometer of the atmosphere. These areas are found predominantly east of North America over the Gulf Stream, and, off East Asia over the Kuroshio Current. Accompanying the high lapse rates are low air temperatures, large sea-air temperature differences, and low relative humidities. Imagery from a Visible / Near Infrared instrument on the AIRS experiment shows accompanying clouds. These lines of evidence all point to shallow convection in the bottom layer of a cold air mass overlying warm water, with overturning driven by heat flow from ocean to atmosphere. An examination of operational radiosondes at six coastal stations in Japan shows AIRS to be oversensitive to lower tropospheric lapse rates due to systematically warm near-surface air temperatures. The bias in near-surface air temperature is seen to be independent of sea surface temperature, however. AIRS is therefore sensitive to air-sea temperature difference, but with a warm atmospheric bias. A regression fit to radiosondes is used to correct AIRS near-surface retrieved temperatures, and thereby obtain an estimate of the true atmosphere-ocean thermal contrast in five subtropical regions across the north Pacific. Moving eastward, we show a systematic shift in this air-sea temperature differences toward more isothermal conditions. These results, while preliminary, have implications for our understanding of heat flow from ocean to

  3. Improving stopping construction to minimize leakage

    PubMed Central

    Grau, Roy H.; Mazzella, Andrew L.; Martikainen, Anu L.

    2015-01-01

    The proper sealing of stoppings is an important step in reducing leakage from the intake to the return airways. Leakage and the subsequent loss of ventilation resulting from improperly sealed stoppings can lead to unhealthy and unsafe working conditions. The research presented in this paper investigates the total leakage of a stopping, including air leakage through the stopping, at the stopping perimeter, and through the coalbed. The study also examines sealing considerations for stoppings that are constructed under roof control screen, the effects that wooden wedges had on inhibiting efficient application of polyurethane foam sealant, and airflow leakage through the surrounding coal. The work involved building a stopping in a dead end room of the NIOSH Safety Research Coal Mine and then pressurising the room using compressed air. Stopping leakage was evaluated by measuring air pressure loss in the enclosed room due to the air leakage. Part of the research utilises a diluted soap solution that was applied to the stopping and the surrounding coal to detect air leakage signified by bubble formations. The results show that stopping leakage can be minimised with proper sealing PMID:26379366

  4. Ventilating-air change rate versus particulate contaminant spread

    SciTech Connect

    Langer, G.; Deitesfeld, C.A.

    1987-11-13

    This study provides information on the spread of particulate contamination from glovebox leaks in plutonium manufacturing facilities, with emphasis on the effect of ventilating-air change rate on contaminated spread. A new, very sensitive aerosol tracer technique was developed to simulate plutonium aerosol leaks and its dispersion in a room. The tracer, a submicron aerosol of phloroglucinol, does not interfere with work activity and is detected by its ability to form ice crystals in a supercooled cloud. This technique was applied in Buildings 371 and 707 plutonium production areas. The tracer spread throughout the rooms in a few minutes and reached its equilibrium concentration in 10 to 25 min. Also, to clear the room of all tracer took about the same time. In one room, tracer concentration decreased proportionally to the air change rate, while in the second one, air change rate had no effect. This points out the need for air velocity data. Also, future work must include simultaneous particle concentration measurements at several points. 4 refs., 9 figs., 2 tabs.

  5. Versatile radar measurement of the electron loss rate in air

    SciTech Connect

    Dogariu, Arthur; Shneider, Mikhail N.; Miles, Richard B.

    2013-11-25

    We present an experimental method that makes possible in-situ measurements of the electron loss rate in arbitrary gas mixtures. A weakly ionized plasma is induced via resonant multiphoton ionization of trace amounts of nitric oxide seeded into the gas, and homodyne microwave scattering detection is used to study the dynamics of the electron loss mechanisms. Using this approach, the attachment rate for electrons to molecular oxygen in room temperature, atmospheric pressure air is determined. The measured 0.76 × 10{sup 8} s{sup −1} attachment rate is in very good agreement with predictions based on literature data.

  6. Air traffic control surveillance accuracy and update rate study

    NASA Technical Reports Server (NTRS)

    Craigie, J. H.; Morrison, D. D.; Zipper, I.

    1973-01-01

    The results of an air traffic control surveillance accuracy and update rate study are presented. The objective of the study was to establish quantitative relationships between the surveillance accuracies, update rates, and the communication load associated with the tactical control of aircraft for conflict resolution. The relationships are established for typical types of aircraft, phases of flight, and types of airspace. Specific cases are analyzed to determine the surveillance accuracies and update rates required to prevent two aircraft from approaching each other too closely.

  7. Yaw rate control of an air bearing vehicle

    NASA Technical Reports Server (NTRS)

    Walcott, Bruce L.

    1989-01-01

    The results of a 6 week project which focused on the problem of controlling the yaw (rotational) rate the air bearing vehicle used on NASA's flat floor facility are summarized. Contained within is a listing of the equipment available for task completion and an evaluation of the suitability of this equipment. The identification (modeling) process of the air bearing vehicle is detailed as well as the subsequent closed-loop control strategy. The effectiveness of the solution is discussed and further recommendations are included.

  8. Augmented PMMA distribution: improvement of mechanical property and reduction of leakage rate of a fenestrated pedicle screw with diameter-tapered perforations.

    PubMed

    Tan, Quan-Chang; Wu, Jian-Wei; Peng, Fei; Zang, Yuan; Li, Yang; Zhao, Xiong; Lei, Wei; Wu, Zi-Xiang

    2016-06-01

    OBJECTIVE This study investigated the optimum injection volume of polymethylmethacrylate (PMMA) to augment a novel fenestrated pedicle screw (FPS) with diameter-tapered perforations in the osteoporotic vertebral body, and how the distribution characteristics of PMMA affect the biomechanical performance of this screw. METHODS Two types of FPSs were designed (FPS-A, composed of 6 perforations with an equal diameter of 1.2 mm; and FPS-B, composed of 6 perforations each with a tapered diameter of 1.5 mm, 1.2 mm, and 0.9 mm from tip to head. Each of 28 human cadaveric osteoporotic vertebrae were randomly assigned to 1 of 7 groups: FPS-A1.0: FPS-A+1.0 ml PMMA; FPS-A1.5: FPS-A+1.5 ml PMMA; FPS-A2.0: FPS-A+2.0 ml PMMA; FPS-B1.0: FPS-B+1.0 ml PMMA; FPS-B1.5: FPS-B+1.5 ml PMMA; FPS-B2.0: FPS-B+2.0 ml PMMA; and conventional pedicle screws (CPSs) without PMMA. After the augmentation, 3D CT was performed to assess the cement distribution characteristics and the cement leakage rate. Axial pullout tests were performed to compare the maximum pullout force thereafter. RESULTS The CT construction images showed that PMMA bone cement formed a conical mass around FPS-A and a cylindrical mass around FPS-B. When the injection volume was increased from 1.0 ml to 2.0 ml, the distribution region of the PMMA cement was enlarged, the PMMA was distributed more posteriorly, and the risk of leakage was increased. When the injection volume reached 2.0 ml, the risk of cement leakage was lower for screws having diameter-tapered perforations. The pullout strengths of the augmented FPS-A groups and FPS-B groups were higher than that of the CPS group (p < 0.0001). All FPS-B groups had a higher pullout strength than the FPS-A groups. CONCLUSIONS The diameter of the perforations affects the distribution of PMMA cement. The diameter-tapered design enabled PMMA to form larger bone-PMMA interfaces and achieve a relatively higher pullout strength, although statistical significance was not reached. Study

  9. Modeling spatial and temporal variability of residential air exchange rates for the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS).

    PubMed

    Breen, Michael S; Burke, Janet M; Batterman, Stuart A; Vette, Alan F; Godwin, Christopher; Croghan, Carry W; Schultz, Bradley D; Long, Thomas C

    2014-11-01

    Air pollution health studies often use outdoor concentrations as exposure surrogates. Failure to account for variability of residential infiltration of outdoor pollutants can induce exposure errors and lead to bias and incorrect confidence intervals in health effect estimates. The residential air exchange rate (AER), which is the rate of exchange of indoor air with outdoor air, is an important determinant for house-to-house (spatial) and temporal variations of air pollution infiltration. Our goal was to evaluate and apply mechanistic models to predict AERs for 213 homes in the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS), a cohort study of traffic-related air pollution exposures and respiratory effects in asthmatic children living near major roads in Detroit, Michigan. We used a previously developed model (LBL), which predicts AER from meteorology and questionnaire data on building characteristics related to air leakage, and an extended version of this model (LBLX) that includes natural ventilation from open windows. As a critical and novel aspect of our AER modeling approach, we performed a cross validation, which included both parameter estimation (i.e., model calibration) and model evaluation, based on daily AER measurements from a subset of 24 study homes on five consecutive days during two seasons. The measured AER varied between 0.09 and 3.48 h(-1) with a median of 0.64 h(-1). For the individual model-predicted and measured AER, the median absolute difference was 29% (0.19 h‑1) for both the LBL and LBLX models. The LBL and LBLX models predicted 59% and 61% of the variance in the AER, respectively. Daily AER predictions for all 213 homes during the three year study (2010-2012) showed considerable house-to-house variations from building leakage differences, and temporal variations from outdoor temperature and wind speed fluctuations. Using this novel approach, NEXUS will be one of the first epidemiology studies to apply calibrated and

  10. Modeling Spatial and Temporal Variability of Residential Air Exchange Rates for the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS)

    PubMed Central

    Breen, Michael S.; Burke, Janet M.; Batterman, Stuart A.; Vette, Alan F.; Godwin, Christopher; Croghan, Carry W.; Schultz, Bradley D.; Long, Thomas C.

    2014-01-01

    Air pollution health studies often use outdoor concentrations as exposure surrogates. Failure to account for variability of residential infiltration of outdoor pollutants can induce exposure errors and lead to bias and incorrect confidence intervals in health effect estimates. The residential air exchange rate (AER), which is the rate of exchange of indoor air with outdoor air, is an important determinant for house-to-house (spatial) and temporal variations of air pollution infiltration. Our goal was to evaluate and apply mechanistic models to predict AERs for 213 homes in the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS), a cohort study of traffic-related air pollution exposures and respiratory effects in asthmatic children living near major roads in Detroit, Michigan. We used a previously developed model (LBL), which predicts AER from meteorology and questionnaire data on building characteristics related to air leakage, and an extended version of this model (LBLX) that includes natural ventilation from open windows. As a critical and novel aspect of our AER modeling approach, we performed a cross validation, which included both parameter estimation (i.e., model calibration) and model evaluation, based on daily AER measurements from a subset of 24 study homes on five consecutive days during two seasons. The measured AER varied between 0.09 and 3.48 h−1 with a median of 0.64 h−1. For the individual model-predicted and measured AER, the median absolute difference was 29% (0.19 h‑1) for both the LBL and LBLX models. The LBL and LBLX models predicted 59% and 61% of the variance in the AER, respectively. Daily AER predictions for all 213 homes during the three year study (2010–2012) showed considerable house-to-house variations from building leakage differences, and temporal variations from outdoor temperature and wind speed fluctuations. Using this novel approach, NEXUS will be one of the first epidemiology studies to apply calibrated

  11. Predicting Envelope Leakage in Attached Dwellings

    SciTech Connect

    Faakye, O.; Arena, L.; Griffiths, D.

    2013-07-01

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

  12. The Effects of Air Pollution on Ischemic Stroke Admission Rate

    PubMed Central

    Alimohammadi, Hossein; Fakhri, Sara; Derakhshanfar, Hojjat; Hosseini-Zijoud, Seyed-Mostafa; Safari, Saeed

    2016-01-01

    The present study aimed to determine the relationship between the level of air pollutants and the rate of ischemic stroke (IS) admissions to hospitals. In this retrospective cross-sectional study, stroke admissions (January-March 2012 and 2013) to an emergency department and air pollution and meteorological data were gathered. The relationship between air pollutant levels and hospital admission rates were evaluated using the generalize additive model. In all 379 patients with IS were referred to the hospital (52.5% male; mean age 68.2±13.3 years). Both transient (p<0.001) and long-term (p<0.001) rises in CO level increases the risk of IS. Increased weekly (p<0.001) and monthly (p<0.001) average O3 levels amplifies this risk, while a transient increase in NO2 (p<0.001) and SO2 (p<0.001) levels has the same effect. Long-term changes in PM10 (p<0.001) and PM2.5 (p<0.001) also increase the risk of IS. The findings showed that the level of air pollutants directly correlates with the number of stroke admissions to the emergency department. PMID:26866000

  13. The Effects of Air Pollution on Ischemic Stroke Admission Rate.

    PubMed

    Alimohammadi, Hossein; Fakhri, Sara; Derakhshanfar, Hojjat; Hosseini-Zijoud, Seyed-Mostafa; Safari, Saeed; Hatamabadi, Hamid Reza

    2016-01-01

    The present study aimed to determine the relationship between the level of air pollutants and the rate of ischemic stroke (IS) admissions to hospitals. In this retrospective cross-sectional study, stroke admissions (January-March 2012 and 2013) to an emergency department and air pollution and meteorological data were gathered. The relationship between air pollutant levels and hospital admission rates were evaluated using the generalize additive model. In all 379 patients with IS were referred to the hospital (52.5% male; mean age 68.2±13.3 years). Both transient (p<0.001) and long-term (p<0.001) rises in CO level increases the risk of IS. Increased weekly (p<0.001) and monthly (p<0.001) average O3 levels amplifies this risk, while a transient increase in NO2 (p<0.001) and SO2 (p<0.001) levels has the same effect. Long-term changes in PM10 (p<0.001) and PM2.5 (p<0.001) also increase the risk of IS. The findings showed that the level of air pollutants directly correlates with the number of stroke admissions to the emergency department. PMID:26866000

  14. Air Controlman 3 and 2: Naval Rate Training Manual and Nonresident Career Course.

    ERIC Educational Resources Information Center

    Naval Education and Training Command, Pensacola, FL.

    The Rate Training Manual is one of a series of training manuals prepared for enlisted personnel of the Navy and Naval Reserve studying for advancement in the Air Controlman (AC) rating to Air Controlman Third and Second Class. Chapter 1 discusses air controlman qualifications, the enlisted rating structure, the Air Controlman rating, references…

  15. Flows with tip leakage

    NASA Astrophysics Data System (ADS)

    Moore, John

    The flow development within the tip gap and the flow tip leakage, applying Navier-Stokes codes, are discussed. The loss production, the turbine inefficiency and the heat transfer to the blade tip, are considered. The measurements and calculations used demonstrate features of the flow, such as separation and reattachment on the blade tip, shock formation in the tip gap, and formation and dissipation of tip gap secondary kinetic energy. A procedure for calculating turbine blade tip temperatures is included. The results for a centrifugal compressor show the interaction of the tip leakage and passage flows. The radial blackflow near the shroud wall at low off-design flow rates is considered. The calculations demonstrate the potential use of a computational fluid dynamics code for predicting a centrifugal compressor map.

  16. The air-kerma rate constant of 192Ir.

    PubMed

    Ninković, M M; Raiĉevìć, J J

    1993-01-01

    The air-kerma rate constant gamma delta (and its precursors), as one of the basic radiation characteristics of 192Ir, was determined by many authors. Analysis of accessible data on this quantity led us to the conclusion that published data strongly disagree. That is the reason we calculated this quantity on the basis of our and many other authors' gamma-ray spectral data and the latest data for mass energy-transfer coefficients for air. In this way, a value was obtained for gamma delta of 30.0 +/- 0.9 a Gy m2 s-1 Bq-1 for an unshielded 192Ir source and 27.8 +/- 0.9 a Gy m2s -1Bq-1 for a standard packaged radioactive source taking into account attenuation of gamma rays in the platinum source wall. PMID:8416220

  17. Expected rates with mini-arrays for air showers

    NASA Technical Reports Server (NTRS)

    Hazen, W. E.

    1985-01-01

    As a guide in the design of mini-arrays used to exploit the Linsley effect in the study of air showers, it is useful to calculate the expected rates. The results can aid in the choice of detectors and their placement or in predicting the utility of existing detector systems. Furthermore, the potential of the method can be appraised for the study of large showers. Specifically, we treat the case of a mini-array of dimensions small enough compared to the distance of axes of showers of interest so that it can be considered a point detector. The input information is taken from the many previous studies of air showers by other groups. The calculations will give: (1) the expected integral rate, F(sigma, rho), for disk thickness, sigma, or rise time, t sub 1/2, with local particle density, rho, as a parameter; (2) the effective detection area A(N) with sigma (min) and rho (min) and rho (min) as parameters; (3) the expected rate of collection of data F sub L (N) versus shower size, N.

  18. Prototype Systems for Measuring Outdoor Air Intake Rates in Rooftop Air Handlers

    SciTech Connect

    Fisk, William J.; Chan, Wanyu R.; Hotchi, Toshifumi

    2015-01-01

    The widespread absence of systems for real-time measurement and feedback control, of minimum outdoor air intake rates in HVAC systems contributes to the poor control of ventilation rates in commercial buildings. Ventilation rates affect building energy consumption and influence occupant health. The project designed fabricated and tested four prototypes of systems for measuring rates of outdoor air intake into roof top air handlers. All prototypes met the ±20% accuracy target at low wind speeds, with all prototypes accurate within approximately ±10% after application of calibration equations. One prototype met the accuracy target without a calibration. With two of four prototype measurement systems, there was no evidence that wind speed or direction affected accuracy; however, winds speeds were generally below usually 3.5 m s-1 (12.6 km h-1) and further testing is desirable. The airflow resistance of the prototypes was generally less than 35 Pa at maximum RTU air flow rates. A pressure drop of this magnitude will increase fan energy consumption by approximately 4%. The project did not have resources necessary to estimate costs of mass produced systems. The retail cost of components and materials used to construct prototypes ranged from approximately $1,200 to $1,700. The test data indicate that the basic designs developed in this project, particularly the designs of two of the prototypes, have considerable merit. Further design refinement, testing, and cost analysis would be necessary to fully assess commercial potential. The designs and test results will be communicated to the HVAC manufacturing community.

  19. Air exchange rates from atmospheric CO2 daily cycle

    PubMed Central

    Carrilho, João Dias; Mateus, Mário; Batterman, Stuart; da Silva, Manuel Gameiro

    2015-01-01

    We propose a new approach for measuring ventilation air exchange rates (AERs). The method belongs to the class of tracer gas techniques, but is formulated in the light of systems theory and signal processing. Unlike conventional CO2 based methods that assume the outdoor ambient CO2 concentration is constant, the proposed method recognizes that photosynthesis and respiration cycle of plants and processes associated with fuel combustion produce daily, quasi-periodic, variations in the ambient CO2 concentrations. These daily variations, which are within the detection range of existing monitoring equipment, are utilized for estimating ventilation rates without the need of a source of CO2 in the building. Using a naturally-ventilated residential apartment, AERs obtained using the new method compared favorably (within 10%) to those obtained using the conventional CO2 decay fitting technique. The new method has the advantages that no tracer gas injection is needed, and high time resolution results are obtained. PMID:26236090

  20. Predicting Envelope Leakage in Attached Dwellings (Fact Sheet)

    SciTech Connect

    Not Available

    2013-11-01

    The most common method of measuring air leakage is to perform single (or solo) blower door pressurization and/or depressurization test. In detached housing, the single blower door test measures leakage to the outside. In attached housing, however, this "solo" test method measures both air leakage to the outside and air leakage between adjacent units through common surfaces. Although minimizing leakage to neighboring units is highly recommended to avoid indoor air quality issues between units, reduce pressure differentials between units, and control stack effect, the energy benefits of air sealing can be significantly overpredicted if the solo air leakage number is used in the energy analysis. Guarded blower door testing is more appropriate for isolating and measuring leakage to the outside in attached housing. This method uses multiple blower doors to depressurize adjacent spaces to the same level as the unit being tested. Maintaining a neutral pressure across common walls, ceilings, and floors acts as a "guard" against air leakage between units. The resulting measured air leakage in the test unit is only air leakage to the outside. Although preferred for assessing energy impacts, the challenges of performing guarded testing can be daunting.

  1. Evaluating effective reaction rates of kinetically driven solutes in large-scale, anisotropic media: human health risk implications in CO2 leakage

    NASA Astrophysics Data System (ADS)

    Siirila, E. R.; Maxwell, R. M.

    2011-12-01

    The role of high and low hydraulic conductivity (K) regions in heterogeneous, stratified and non-stratified flow fields and the subsequent effect of rate dependent geochemical reactions are investigated with regards to mobilized arsenic from CO2 leakage at a Carbon Capture and Storage (CCS) site. Following the methodology of previous work, human health risk is used as an endpoint for comparison via a two-stage or nested Monte Carlo scheme, explicitly considering joint uncertainty and variability for a hypothetical population of individuals. This study identifies geo-hydrologic conditions where solute reactions are either rate limited (non-reactive), in equilibrium (linear equilibrium assumption, LEA, is appropriate), or are sensitive to time-dependent kinetic reaction rates. Potential interplay between multiple parameters (i.e. positive or negative feedbacks) is shown utilizing stochastic ensembles. In particular, the effect of preferential flow pathways and solute mixing on the field-scale (macrodispersion) and sub-grid (local dispersion) is examined for varying degrees of stratification and regional groundwater velocities. Results show effective reaction rates of kinetic ensembles are dissimilar from LEA ensembles with the inclusion of local dispersion, resulting in an additive tailing effect of the solute plume, a retarded peak time, and an increased cancer risk. This discrepancy between kinetic and LEA ensembles is augmented in highly anisotropic media, especially at intermediate regional groundwater velocities. The distribution, magnitude, and associated uncertainty of cancer risk are controlled by these factors, but are also strongly dependent on the regional groundwater velocity. We demonstrate a higher associated uncertainty of cancer risk in stratified domains is linked to higher aquifer connectivity and less macrodispersion in the flow field. This study has implications in CCS site selection and groundwater driven risk assessment modeling.

  2. Relativistic collision rate calculations for electron-air interactions

    SciTech Connect

    Graham, G.; Roussel-Dupre, R.

    1993-12-01

    The most recent data available on differential cross sections for electron-air interactions are used to calculate the avalanche, momentum transfer, and energy loss rates that enter into the fluid equations. Data for the important elastic, inelastic, and ionizing processes are generally available out to electron energies of 1--10 keV. Prescriptions for extending these cross sections to the relativistic regime are presented. The angular dependence of the cross sections is included where data are available as is the doubly differential cross section for ionizing collisions. The collision rates are computed by taking moments of the Boltzmann collision integrals with the assumption that the electron momentum distribution function is given by the Juettner distribution function which satisfies the relativistic H- theorem and which reduces to the familiar Maxwellian velocity distribution in the nonrelativistic regime. The distribution function is parameterized in terms of the electron density, mean momentum, and thermal energy and the rates are therefore computed on a two dimensional grid as a function of mean kinetic energy and thermal energy.

  3. Relativistic collision rate calculations for electron-air interactions

    SciTech Connect

    Graham, G.; Roussel-Dupre, R.

    1992-12-16

    The most recent data available on differential cross sections for electron-air interactions are used to calculate the avalanche, momentum transfer, and energy loss rates that enter into the fluid equations. Data for the important elastic, inelastic, and ionizing processes are generally available out to electron energies of 1--10 kev. Prescriptions for extending these cross sections to the relativistic regime are presented. The angular dependence of the cross sections is included where data is available as is the doubly differential cross section for ionizing collisions. The collision rates are computed by taking moments of the Boltzmann collision integrals with the assumption that the electron momentum distribution function is given by the Juettner distribution function which satisfies the relativistic H- theorem and which reduces to the familiar Maxwellian velocity distribution in the nonrelativistic regime. The distribution function is parameterized in terms of the electron density, mean momentum, and thermal energy and the rates are therefore computed on a two-dimensional grid as a function of mean kinetic energy and thermal energy.

  4. Heart-rate monitoring by air pressure and causal analysis

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Naoki; Nakajima, Hiroshi; Hata, Yutaka

    2011-06-01

    Among lots of vital signals, heart-rate (HR) is an important index for diagnose human's health condition. For instance, HR provides an early stage of cardiac disease, autonomic nerve behavior, and so forth. However, currently, HR is measured only in medical checkups and clinical diagnosis during the rested state by using electrocardiograph (ECG). Thus, some serious cardiac events in daily life could be lost. Therefore, a continuous HR monitoring during 24 hours is desired. Considering the use in daily life, the monitoring should be noninvasive and low intrusive. Thus, in this paper, an HR monitoring in sleep by using air pressure sensors is proposed. The HR monitoring is realized by employing the causal analysis among air pressure and HR. The causality is described by employing fuzzy logic. According to the experiment on 7 males at age 22-25 (23 on average), the correlation coefficient against ECG is 0.73-0.97 (0.85 on average). In addition, the cause-effect structure for HR monitoring is arranged by employing causal decomposition, and the arranged causality is applied to HR monitoring in a setting posture. According to the additional experiment on 6 males, the correlation coefficient is 0.66-0.86 (0.76 on average). Therefore, the proposed method is suggested to have enough accuracy and robustness for some daily use cases.

  5. Exposure Modeling of Residential Air Exchange Rates for NEXUS Participants.

    EPA Science Inventory

    Due to cost and participant burden of personal measurements, air pollution health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect personal exposures, we developed the Exposure Model for Individuals (EMI) to improv...

  6. Exposure Modeling of Residential Air Exchange Rates for NEXUS Participants

    EPA Science Inventory

    Due to cost and participant burden of personal measurements, air pollution health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect personal exposures, we developed the Exposure Model for Individuals (EMI) to improv...

  7. Robust characterization of leakage errors

    NASA Astrophysics Data System (ADS)

    Wallman, Joel J.; Barnhill, Marie; Emerson, Joseph

    2016-04-01

    Leakage errors arise when the quantum state leaks out of some subspace of interest, for example, the two-level subspace of a multi-level system defining a computational ‘qubit’, the logical code space of a quantum error-correcting code, or a decoherence-free subspace. Leakage errors pose a distinct challenge to quantum control relative to the more well-studied decoherence errors and can be a limiting factor to achieving fault-tolerant quantum computation. Here we present a scalable and robust randomized benchmarking protocol for quickly estimating the leakage rate due to an arbitrary Markovian noise process on a larger system. We illustrate the reliability of the protocol through numerical simulations.

  8. 40 CFR 91.324 - Analyzer leakage check.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Analyzer leakage check. (a) Vacuum side leak check. (1) Check any location within the analysis system where a vacuum leak could affect the test results. (2) The maximum allowable leakage rate on the...

  9. 40 CFR 91.324 - Analyzer leakage check.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Analyzer leakage check. (a) Vacuum side leak check. (1) Check any location within the analysis system where a vacuum leak could affect the test results. (2) The maximum allowable leakage rate on the...

  10. 40 CFR 91.324 - Analyzer leakage check.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Analyzer leakage check. (a) Vacuum side leak check. (1) Check any location within the analysis system where a vacuum leak could affect the test results. (2) The maximum allowable leakage rate on the...

  11. 40 CFR 91.324 - Analyzer leakage check.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Analyzer leakage check. (a) Vacuum side leak check. (1) Check any location within the analysis system where a vacuum leak could affect the test results. (2) The maximum allowable leakage rate on the...

  12. 40 CFR 91.324 - Analyzer leakage check.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Analyzer leakage check. (a) Vacuum side leak check. (1) Check any location within the analysis system where a vacuum leak could affect the test results. (2) The maximum allowable leakage rate on the...

  13. Estimation of uncertainty in tracer gas measurement of air change rates.

    PubMed

    Iizuka, Atsushi; Okuizumi, Yumiko; Yanagisawa, Yukio

    2010-12-01

    Simple and economical measurement of air change rates can be achieved with a passive-type tracer gas doser and sampler. However, this is made more complex by the fact many buildings are not a single fully mixed zone. This means many measurements are required to obtain information on ventilation conditions. In this study, we evaluated the uncertainty of tracer gas measurement of air change rate in n completely mixed zones. A single measurement with one tracer gas could be used to simply estimate the air change rate when n = 2. Accurate air change rates could not be obtained for n ≥ 2 due to a lack of information. However, the proposed method can be used to estimate an air change rate with an accuracy of <33%. Using this method, overestimation of air change rate can be avoided. The proposed estimation method will be useful in practical ventilation measurements. PMID:21318005

  14. HAZARDOUS AIR POLLUTANTS: WET REMOVAL RATES AND MECHANISMS

    EPA Science Inventory

    Fourteen hazardous organic air pollutants were evaluated for their potentials to be wet deposited by precipitation scavenging. This effort included a survey of solubilities (Henry's Law constants) in the literature, measurement of solubilities of three selected species, developme...

  15. REFINED PHOTOLYSIS RATES FOR ADVANCED AIR QUALITY MODELING SYSTEM

    EPA Science Inventory

    Accurate modeling of photochemistry is critical and fundamental to reducing the uncertainty in air quality model predictions. lmost all chemical reactions in the atmosphere are initiated by the photodissociation of a number of trace gases. irect measure of this photodissociation ...

  16. Brush seal leakage performance with gaseous working fluids at static and low rotor speed conditions

    NASA Technical Reports Server (NTRS)

    Carlile, Julie A.; Hendricks, Robert C.; Yoder, Dennis A.

    1992-01-01

    The leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was studied. The leakage results included for air, helium, and carbon dioxide at several bristle/rotor interferences. Also, the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were studied. Results were compared to that of an annular seal at similar operating conditions. In order to generalize the results, they were correlated using corresponding state theory. The brush seal tested had a bore diameter of 3.792 cm (1.4930 in.), a fence height of 0.0635 cm (0.025 in.), and 1800 bristles/cm circumference (4500 bristles/in. circumference). Various bristle/rotor radial interferences were achieved by using a tapered rotor. The brush seal reduced the leakage in comparison to the annular seal, up to 9.5 times. Reversing the pressure drop across the brush seal produced leakage rates approximately the same as that of the annular seal. Addition of a lubricant reduced the leakage by 2.5 times. The air and carbon dioxide data were successfully correlated using corresponding state theory. However, the helium data followed a different curve than the air and carbon dioxide data.

  17. Brush seal leakage performance with gaseous working fluids at static and low rotor speed conditions

    NASA Technical Reports Server (NTRS)

    Carlile, Julie A.; Hendricks, Robert C.; Yoder, Dennis A.

    1992-01-01

    The leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was studied. The leakage results are included for air, helium, and carbon dioxide at several bristle/rotor interferences. Also, the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were studied. Results were compared to that of an annular seal at similar operating conditions. In order to generalize the results, they were correlated using corresponding state theory. The brush seal tested had a bore diameter of 3.792 cm (1.4930 in), a fence height of 0.0635 cm (0.025 in), and 1800 bristles/cm circumference (4500 bristles/in circumference). Various bristle/rotor radial interferences were achieved by using a tapered rotor. The brush seal reduced the leakage in comparison to the annular seal, up to 9.5 times. Reversing the pressure drop across the brush seal produced leakage rates approx. the same as that of the annular seal. Addition of a lubricant reduced the leakage by 2.5 times. The air and carbon dioxide data were successfully correlated using corresponding state theory. However, the helium data followed a different curve than the air and carbon dioxide data.

  18. Duct Leakage Repeatability Testing

    SciTech Connect

    Walker, Iain; Sherman, Max

    2014-01-01

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

  19. Multifamily Envelope Leakage Model

    SciTech Connect

    Faakye, Omari; Griffiths, Dianne

    2015-05-08

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

  20. Effect of wind tunnel air velocity on VOC flux rates from CAFO manure and wastewater

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind tunnels and flux chambers are often used to estimate volatile organic compound (VOC) emissions from animal feeding operations (AFOs) without regard to air velocity or sweep air flow rates. Laboratory experiments were conducted to evaluate the effect of wind tunnel air velocity on VOC emission ...

  1. Land-use Leakage

    SciTech Connect

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

    2009-12-01

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

  2. Effects of energy-efficient ventilation rates on indoor air quality at an Ohio elementary school

    NASA Astrophysics Data System (ADS)

    Berk, J. V.; Young, R.; Hollowell, C. D.; Turiel, I.; Pepper, J.

    1980-04-01

    A mobile laboratory was used to monitor air outdoors and at three indoor sites (two classrooms and a large multipurpose room); tests were made at three different ventilation rates. The parameters measured were outside air flow rates, odor perception, microbial burden, particulate mass, total aldehydes, carbon dioxide, ozone, and nitrogen oxides. The results of these measurements are given and compared with the existing outdoor air quality standards. Carbon dioxide concentrations increased as the ventilation rate decreased, but still did not exceed current standards. Odor perceptibility increased slightly at the lowest ventilation rate. Other pollutants showed very low concentrations, which did not change with reductions in ventilation rate.

  3. VOLATILIZATION RATES FROM WATER TO INDOOR AIR PHASE II

    EPA Science Inventory

    Contaminated water can lead to volatilization of chemicals to residential indoor air. Previous research has focused on only one source (shower stalls) and has been limited to chemicals in which gas-phase resistance to mass transfer is of marginal significance. As a result, attemp...

  4. Spatiotemporally‐Resolved Air Exchange Rate as a Modifier of Acute Air Pollution‐Related Morbidity in AtlantaMorbidity in Atlanta

    EPA Science Inventory

    Epidemiological studies frequently use central site concentrations as surrogates of exposure to air pollutants. Variability in air pollutant infiltration due to differential air exchange rates (AERs) is potentially a major factor affecting the relationship between central site c...

  5. Predicting Leakage in Labyrinth Seals

    NASA Technical Reports Server (NTRS)

    Morrison, G. L.; Rhode, D. L.; Cogan, K. C.; Chi, D.; Demko, J.

    1985-01-01

    Analytical and empirical methods evaluated. 264-page report presents comprehensive information on leakage in labyrinth seals. Summarizes previous analyses of leakage, reviews leakage tests conducted by authors and evaluates various analytical and experimental methods of determining leakage and discusses leakage prediction techniques.

  6. Apparatus for detecting leakage of liquid sodium

    DOEpatents

    Himeno, Yoshiaki

    1978-01-01

    An apparatus for detecting the leakage of liquid sodium includes a cable-like sensor adapted to be secured to a wall of piping or other equipment having sodium on the opposite side of the wall, and the sensor includes a core wire electrically connected to the wall through a leak current detector and a power source. An accidental leakage of the liquid sodium causes the corrosion of a metallic layer and an insulative layer of the sensor by products resulted from a reaction of sodium with water or oxygen in the atmospheric air so as to decrease the resistance between the core wire and the wall. Thus, the leakage is detected as an increase in the leaking electrical current. The apparatus is especially adapted for use in detecting the leakage of liquid sodium from sodium-conveying pipes or equipment in a fast breeder reactor.

  7. Leakage and Power Loss Test Results for Competing Turbine Engine Seals

    NASA Technical Reports Server (NTRS)

    Proctor, Margaret P.; Delgado, Irebert R.

    2004-01-01

    Advanced brush and finger seal technologies offer reduced leakage rates over conventional labyrinth seals used in gas turbine engines. To address engine manufacturers concerns about the heat generation and power loss from these contacting seals, brush, finger, and labyrinth seals were tested in the NASA High Speed, High Temperature Turbine Seal Test Rig. Leakage and power loss test results are compared for these competing seals for operating conditions up to 922 K (1200 F) inlet air temperature, 517 KPa (75 psid) across the seal, and surface velocities up to 366 m/s (1200 ft/s).

  8. Rating procedure for mixed-air-source unitary air conditioners and heat pumps operating in the cooling mode

    SciTech Connect

    Domanski, P.A.

    1986-02-01

    A procedure is presented for rating split, residential air conditioners and heat pumps operating in the cooling mode that are made up of an evaporator unit combined with a condensing unit that has been rated under current procedures in conjunction with a different evaporator unit. The procedure allows calculation of capacity at the 95/sup 0/ F rating point and seasonal energy efficiency ratio, SEER, without performing laboratory tests of the complete system.

  9. Shroud leakage flow discouragers

    DOEpatents

    Bailey, Jeremy Clyde; Bunker, Ronald Scott

    2002-01-01

    A turbine assembly includes a plurality of rotor blades comprising a root portion, an airfoil having a pressure sidewall and a suction sidewall, and a top portion having a cap. An outer shroud is concentrically disposed about said rotor blades, said shroud in combination with said tip portions defining a clearance gap. At least one circumferential shroud leakage discourager is disposed within the shroud. The leakage discourager(s) increase the flow resistance and thus reduce the flow of hot gas flow leakage for a given pressure differential across the clearance gap to improve overall turbine efficiency.

  10. Wind-tunnel simulation of infiltration across permeable building envelopes: Energy and air pollution exchange rates

    SciTech Connect

    Meroney, R.N.; Neff, D.E.; Birdsall, J.B.

    1995-12-31

    This study investigates the fluid-modeling techniques used to simulate wind-forced natural ventilation rates of rectangular, single-cell low-rise buildings. A 1:25 scale model of the Texas Tech University Wind Engineering Research Field Laboratory is used in a boundary-layer wind tunnel to evaluate alternative strategies for simulating infiltration into permeable buildings. A new approach is proposed which should permit evaluation of a wide range of leakage situations. In addition data is used to critique standard full-scale tracer gas test methods.

  11. The effect of pressure drop on respirator faceseal leakage.

    PubMed

    Janssen, Larry; Weber, Robert

    2005-07-01

    Users of particulate air-purifying respirators are typically told to change their filters when breathing resistance becomes uncomfortable. It has been proposed that a noticeable increase in breathing resistance (pressure drop) may increase airflow through respirator faceseal leaks. This logic has been extended to suggest that respirator user exposure to contaminants may increase because of this theoretical increase in air leakage. Procedures similar to those of previous investigators were used to study this issue. Repeated faceseal leak rate measurements were made at -5.6 through -20.1 mm water pressure drops across the faceseal. Subjects were divided into two groups, representing acceptable fit or unacceptable fit, based on leak rate criteria prescribed by the Occupational Safety and Health Administration (OSHA). Subjects with acceptable fit did not experience an increase in faceseal leak rate with increased pressure drop. Leak rates for subjects with unacceptable fit were highly variable and did not show an association with pressure drop. Results of this study do not support the concept of increased faceseal leakage with increased pressure drop. The evidence does not suggest increased risk of contaminant exposure through the face seal as pressure drop increases. PMID:16020096

  12. Correlation between indoor radon concentration and dose rate in air from terrestrial gamma radiation in Japan.

    PubMed

    Fujimoto, K

    1998-09-01

    A correlation between the indoor radon concentration and dose rate in air from terrestrial gamma radiation is studied using the results of nationwide indoor radon and external exposure surveys, although the surveys were not conducted at the same time nor at the same location. The radon concentration shows a log-normal-like distribution, whereas the terrestrial gamma radiation dose rate in air shows a normal-like distribution. A log-linear scatterplot for each pair of the indoor radon concentration and gamma-ray dose rate in air in each city reveals a clear relationship. The average, maximum, and minimum as well as regression line of radon concentration were found to increase with the gamma-ray dose rate in air. The group in higher quantile of radon concentration shows larger dependence on the gamma-ray dose rate. The rate of increase of radon concentration with the gamma-ray dose rate in air depends on the house structure. The wooden house has a larger rate of increase than the concrete house, and the regression lines cross at high air dose rate. Based on the finding in the present study a certain criterion level of air dose rate could be established and used for an effective survey to find out which houses might require a remedial action in conjunction with other screening tools. The criterion level of air dose rate might be more effective if the level is set for each house structure since the rate of increase of radon concentration depends on house structure. PMID:9721838

  13. Fractal structure of the distributions of air dose rates in Koriyama city in Fukushima.

    PubMed

    Ishihara, Masamichi

    2014-10-01

    The authors investigated the fractal structure of the distributions of air dose rates in Koriyama city in Fukushima using data published by the Fukushima Prefectural and Koriyama City governments. Relative frequency data of air dose rates (strength distribution) could be well fitted with a q-distribution. In the present analysis, the relative frequency decreases approximately as s for high air dose rate values, where the quantity s represents air dose rate. The fractal dimension is a function of the threshold sth of air dose rate. The fractal dimension is approximately 1.59 when sth is the average of the air dose rates in Koriyama (0.9 μSv h) and decreases with increasing the threshold: it is approximately 1.97 for sth = 0.6 μSv h and 1.40 for sth = 1.2 μSv h. These results confirm that the strength distribution behaves like a power function for high air dose rate values and that the fallout pattern can be described as a fractal. PMID:25162424

  14. Absorbed dose rate in air in metropolitan Tokyo before the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Inoue, K; Hosoda, M; Fukushi, M; Furukawa, M; Tokonami, S

    2015-11-01

    The monitoring of absorbed dose rate in air has been carried out continually at various locations in metropolitan Tokyo after the accident of the Fukushima Daiichi Nuclear Power Plant. While the data obtained before the accident are needed to more accurately assess the effects of radionuclide contamination from the accident, detailed data for metropolitan Tokyo obtained before the accident have not been reported. A car-borne survey of the absorbed dose rate in air in metropolitan Tokyo was carried out during August to September 2003. The average absorbed dose rate in air in metropolitan Tokyo was 49±6 nGy h(-1). The absorbed dose rate in air in western Tokyo was higher compared with that in central Tokyo. Here, if the absorbed dose rate indoors in Tokyo is equivalent to that outdoors, the annual effective dose would be calculated as 0.32 mSv y(-1). PMID:25944962

  15. Effect of room air recirculation delay on the decay rate of tracer gas concentration

    SciTech Connect

    Kristoffersen, A.R.; Gadgil, A.J.; Lorenzetti, D.M.

    2004-05-01

    Tracer gas measurements are commonly used to estimate the fresh air exchange rate in a room or building. Published tracer decay methods account for fresh air supply, infiltration, and leaks in ductwork. However, the time delay associated with a ventilation system recirculating tracer back to the room also affects the decay rate. We present an analytical study of tracer gas decay in a well-mixed, mechanically-ventilated room with recirculation. The analysis shows that failing to account for delays can lead to under- or over-estimates of the fresh air supply, depending on whether the decay rate calculation includes the duct volume.

  16. Technology Solutions Case Study: Predicting Envelope Leakage in Attached Dwellings

    SciTech Connect

    2013-11-01

    The most common method of measuring air leakage is to perform single (or solo) blower door pressurization and/or depressurization test. In detached housing, the single blower door test measures leakage to the outside. In attached housing, however, this “solo” test method measures both air leakage to the outside and air leakage between adjacent units through common surfaces. In an attempt to create a simplified tool for predicting leakage to the outside, Building America team Consortium for Advanced Residential Buildings (CARB) performed a preliminary statistical analysis on blower door test results from 112 attached dwelling units in four apartment complexes. Although the subject data set is limited in size and variety, the preliminary analyses suggest significant predictors are present and support the development of a predictive model. Further data collection is underway to create a more robust prediction tool for use across different construction types, climate zones, and unit configurations.

  17. A Review of the Thermodynamic, Transport, and Chemical Reaction Rate Properties of High-temperature Air

    NASA Technical Reports Server (NTRS)

    Hansen, C Frederick; Heims, Steve P

    1958-01-01

    Thermodynamic and transport properties of high temperature air, and the reaction rates for the important chemical processes which occur in air, are reviewed. Semiempirical, analytic expressions are presented for thermodynamic and transport properties of air. Examples are given illustrating the use of these properties to evaluate (1) equilibrium conditions following shock waves, (2) stagnation region heat flux to a blunt high-speed body, and (3) some chemical relaxation lengths in stagnation region flow.

  18. Leakage Suppression in the Toric Code

    NASA Astrophysics Data System (ADS)

    Suchara, Martin; Cross, Andrew; Gambetta, Jay

    2015-03-01

    Quantum codes excel at correcting local noise but fail to correct leakage faults that excite qubits to states outside the computational space. Aliferis and Terhal have shown that an accuracy threshold exists for leakage faults using gadgets called leakage reduction units (LRUs). However, these gadgets reduce the threshold and increase experimental complexity, and the costs have not been thoroughly understood. We explore a variety of techniques for leakage resilience in topological codes. Our contributions are threefold. First, we develop a leakage model that differs in critical details from earlier models. Second, we use Monte-Carlo simulations to survey several syndrome extraction circuits. Third, given the capability to perform 3-outcome measurements, we present a dramatically improved syndrome processing algorithm. Our simulations show that simple circuits with one extra CNOT per qubit reduce the accuracy threshold by less than a factor of 4 when leakage and depolarizing noise rates are comparable. This becomes a factor of 2 when the decoder uses 3-outcome measurements. Finally, when the physical error rate is less than 2 ×10-4 , placing LRUs after every gate may achieve the lowest logical error rate. We expect that the ideas may generalize to other topological codes.

  19. Spatiotemporally-Resolved Air Exchange Rate as a Modifier of Acute Air Pollution-Related Morbidity

    EPA Science Inventory

    The National Exposure Research Laboratory (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA mission to protect human health and the environment. HEASD research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EP...

  20. 49 CFR 178.346-5 - Pressure and leakage tests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... is equipped with vapor recovery equipment may be leakage tested in accordance with 40 CFR 63.425(e). To satisfy the leakage test requirements of this paragraph, the test specified in 40 CFR 63.425(e)(1) must be conducted using air. The hydrostatic test alternative permitted under Appendix A to 40 CFR...

  1. 49 CFR 178.346-5 - Pressure and leakage tests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... is equipped with vapor recovery equipment may be leakage tested in accordance with 40 CFR 63.425(e). To satisfy the leakage test requirements of this paragraph, the test specified in 40 CFR 63.425(e)(1) must be conducted using air. The hydrostatic test alternative permitted under Appendix A to 40 CFR...

  2. 49 CFR 178.346-5 - Pressure and leakage tests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... is equipped with vapor recovery equipment may be leakage tested in accordance with 40 CFR 63.425(e). To satisfy the leakage test requirements of this paragraph, the test specified in 40 CFR 63.425(e)(1) must be conducted using air. The hydrostatic test alternative permitted under Appendix A to 40 CFR...

  3. 49 CFR 178.346-5 - Pressure and leakage tests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... is equipped with vapor recovery equipment may be leakage tested in accordance with 40 CFR 63.425(e). To satisfy the leakage test requirements of this paragraph, the test specified in 40 CFR 63.425(e)(1) must be conducted using air. The hydrostatic test alternative permitted under Appendix A to 40 CFR...

  4. 42 CFR 84.158 - Exhalation valve leakage test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Exhalation valve leakage test. 84.158 Section 84.158 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.158 Exhalation valve leakage...

  5. Zero leakage sealings

    NASA Astrophysics Data System (ADS)

    Kotesovec, Bernhard; Steinrück, Herbert

    2010-11-01

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

  6. Inward leakage in tight-fitting PAPRs.

    PubMed

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

    2011-01-01

    A combination of local flow measurement techniques and fog flow visualization was used to determine the inward leakage for two tight-fitting powered air-purifying respirators (PAPRs), the 3M Breathe-Easy PAPR and the SE 400 breathing demand PAPR. The PAPRs were mounted on a breathing machine head form, and flows were measured from the blower and into the breathing machine. Both respirators leaked a little at the beginning of inhalation, probably through their exhalation valves. In both cases, the leakage was not enough for fog to appear at the mouth of the head form. PMID:21647352

  7. Inward Leakage in Tight-Fitting PAPRs

    PubMed Central

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

    2011-01-01

    A combination of local flow measurement techniques and fog flow visualization was used to determine the inward leakage for two tight-fitting powered air-purifying respirators (PAPRs), the 3M Breathe-Easy PAPR and the SE 400 breathing demand PAPR. The PAPRs were mounted on a breathing machine head form, and flows were measured from the blower and into the breathing machine. Both respirators leaked a little at the beginning of inhalation, probably through their exhalation valves. In both cases, the leakage was not enough for fog to appear at the mouth of the head form. PMID:21647352

  8. Daily changes in oxygen saturation and pulse rate associated with particulate air pollution and barometric pressure.

    PubMed

    Dockery, D W; Pope, C A; Kanner, R E; Martin Villegas, G; Schwartz, J

    1999-01-01

    Epidemiologic studies have linked fine particulate air pollution with increases in morbidity and mortality rates from cardiopulmonary complications. Although the underlying biologic mechanisms responsible for this increase remain largely unknown, potential pathways include transient declines in blood oxygenation and changes in pulse rate following exposures to particulate air pollution episodes. This study evaluated potential associations between daily measures of respirable particulate matter (PM) with pulse rate and oxygen saturation of the blood. Pulse rate and oxygen saturation (Spo2) using pulse oximetry were measured daily in 90 elderly subjects living near air pollution monitors during the winter of 1995-96 in Utah Valley. We also evaluated potential associations of oxygen saturation and pulse rate with barometric pressure. Small but statistically significant positive associations between day-to-day changes in Spo2 and barometric pressure were observed. Pulse rate was inversely associated with barometric pressure. Exposure to particulate pollution was not significantly associated with Spo2 except in male participants 80 years of age or older. Increased daily pulse rate, as well as the odds of having a pulse rate 5 or 10 beats per minute (bpm) above normal (normal is defined as the individual's mean pulse rate throughout the study period), were significantly associated with exposure to particulate pollution on the previous 1 to 5 days. The medical or biologic relevance of these increases in pulse rate following exposure to particulate air pollution requires further study. PMID:10192116

  9. Dosimetric Effects of Air Pockets Around High-Dose Rate Brachytherapy Vaginal Cylinders

    SciTech Connect

    Richardson, Susan; Palaniswaamy, Geethpriya; Grigsby, Perry W.

    2010-09-01

    Purpose: Most physicians use a single-channel vaginal cylinder for postoperative endometrial cancer brachytherapy. Recent published data have identified air pockets between the vaginal cylinders and the vaginal mucosa. The purpose of this research was to evaluate the incidence, size, and dosimetric effects of these air pockets. Methods and Materials: 25 patients receiving postoperative vaginal cuff brachytherapy with a high-dose rate vaginal cylinders were enrolled in this prospective data collection study. Patients were treated with 6 fractions of 200 to 400 cGy per fraction prescribed at 5 mm depth. Computed tomography simulation for brachytherapy treatment planning was performed for each fraction. The quantity, volume, and dosimetric impact of the air pockets surrounding the cylinder were quantified. Results: In 25 patients, a total of 90 air pockets were present in 150 procedures (60%). Five patients had no air pockets present during any of their treatments. The average number of air pockets per patient was 3.6, with the average total air pocket volume being 0.34 cm{sup 3} (range, 0.01-1.32 cm{sup 3}). The average dose reduction to the vaginal mucosa at the air pocket was 27% (range, 9-58%). Ten patients had no air pockets on their first fraction but air pockets occurred in subsequent fractions. Conclusion: Air pockets between high-dose rate vaginal cylinder applicators and the vaginal mucosa are present in the majority of fractions of therapy, and their presence varies from patient to patient and fraction to fraction. The existence of air pockets results in reduced radiation dose to the vaginal mucosa.

  10. Air-water Gas Exchange Rates on a Large Impounded River Measured Using Floating Domes (Poster)

    EPA Science Inventory

    Mass balance models of dissolved gases in rivers typically serve as the basis for whole-system estimates of greenhouse gas emission rates. An important component of these models is the exchange of dissolved gases between air and water. Controls on gas exchange rates (K) have be...

  11. K{sub Air} and H*(10) Rate Constants for Gamma Emitters

    SciTech Connect

    Vega-Carrillo, H. R.; Juarez, R. Rodriguez; Manzanares-Acuna, E.; Davila, V. M. Hernandez; Mercado, G. A.

    2008-08-11

    Monte Carlo calculations have been carried out to estimate the Air Kerma rate constant and the Ambient dose equivalent rate constant for 139 monoenergetic photon sources. The factor that relates activity to air kerma rate or to ambient dose equivalent is useful to estimate the dose from a photon emitter source. Here 139 point-like and monoenergetic gamma-ray sources, ranging from 0.01 to 10 MeV were utilized in Monte Carlo calculations to estimate both gamma factors. These factors were utilized to calculate the air kerma-and-ambient dose equivalent rate constants for {sup 137}Cs-{sup 137m}Ba, {sup 198}Au, {sup 60}Co, and {sup 131}I, whose values were compared with those published in the literature.

  12. Reaction rate constant for dry air oxidation of K Basin fuel

    SciTech Connect

    Trimble, D.J.

    1998-04-29

    The rate of oxidation of spent nuclear fuel stored in the K Basin water is an important parameter when assessing the processes and accident scenarios for preparing the fuel for dry storage. The literature provides data and rate laws for the oxidation of unirradiated uranium in various environments. Measurement data for the dry air oxidation of K Basin fuel is compared to the literature data for linear oxidation in dry air. Equations for the correlations and statistical bounds to the K Basin fuel data and the literature data are selected for predicting nominal and bounding rates for the dry air oxidation of the K Basin fuel. These rate equations are intended for use in the Spent Nuclear Fuel Project Technical Data book.

  13. 40 CFR 89.316 - Analyzer leakage and response time.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Equipment Provisions § 89.316 Analyzer leakage and response time. (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 0.5 percent of the in-use flow rate for...

  14. 40 CFR 89.316 - Analyzer leakage and response time.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Equipment Provisions § 89.316 Analyzer leakage and response time. (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 0.5 percent of the in-use flow rate for...

  15. 40 CFR 90.324 - Analyzer leakage check.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Provisions § 90.324 Analyzer leakage check. (a) Vacuum side leak check. (1) Check any location within the analysis system where a vacuum leak could affect the test results. (2) The maximum allowable leakage rate on the vacuum side is 0.5 percent of the in-use flow rate for the portion of the system being...

  16. 40 CFR 89.316 - Analyzer leakage and response time.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Equipment Provisions § 89.316 Analyzer leakage and response time. (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 0.5 percent of the in-use flow rate for...

  17. 40 CFR 90.324 - Analyzer leakage check.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Provisions § 90.324 Analyzer leakage check. (a) Vacuum side leak check. (1) Check any location within the analysis system where a vacuum leak could affect the test results. (2) The maximum allowable leakage rate on the vacuum side is 0.5 percent of the in-use flow rate for the portion of the system being...

  18. 40 CFR 90.324 - Analyzer leakage check.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Provisions § 90.324 Analyzer leakage check. (a) Vacuum side leak check. (1) Check any location within the analysis system where a vacuum leak could affect the test results. (2) The maximum allowable leakage rate on the vacuum side is 0.5 percent of the in-use flow rate for the portion of the system being...

  19. 40 CFR 90.324 - Analyzer leakage check.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Provisions § 90.324 Analyzer leakage check. (a) Vacuum side leak check. (1) Check any location within the analysis system where a vacuum leak could affect the test results. (2) The maximum allowable leakage rate on the vacuum side is 0.5 percent of the in-use flow rate for the portion of the system being...

  20. 40 CFR 89.316 - Analyzer leakage and response time.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Equipment Provisions § 89.316 Analyzer leakage and response time. (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 0.5 percent of the in-use flow rate for...

  1. 40 CFR 90.324 - Analyzer leakage check.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Provisions § 90.324 Analyzer leakage check. (a) Vacuum side leak check. (1) Check any location within the analysis system where a vacuum leak could affect the test results. (2) The maximum allowable leakage rate on the vacuum side is 0.5 percent of the in-use flow rate for the portion of the system being...

  2. 40 CFR 89.316 - Analyzer leakage and response time.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Equipment Provisions § 89.316 Analyzer leakage and response time. (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 0.5 percent of the in-use flow rate for...

  3. Determination of leakage areas in nuclear piping

    SciTech Connect

    Keim, E.

    1997-04-01

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

  4. Entrainment Rate in Shallow Cumuli: Dependence on Entrained Dry Air Sources and Probability Density Functions

    NASA Astrophysics Data System (ADS)

    Lu, C.; Liu, Y.; Niu, S.; Vogelmann, A. M.

    2012-12-01

    In situ aircraft cumulus observations from the RACORO field campaign are used to estimate entrainment rate for individual clouds using a recently developed mixing fraction approach. The entrainment rate is computed based on the observed state of the cloud core and the state of the air that is laterally mixed into the cloud at its edge. The computed entrainment rate decreases when the air is entrained from increasing distance from the cloud core edge; this is because the air farther away from cloud edge is drier than the neighboring air that is within the humid shells around cumulus clouds. Probability density functions of entrainment rate are well fitted by lognormal distributions at different heights above cloud base for different dry air sources (i.e., different source distances from the cloud core edge). Such lognormal distribution functions are appropriate for inclusion into future entrainment rate parameterization in large scale models. To the authors' knowledge, this is the first time that probability density functions of entrainment rate have been obtained in shallow cumulus clouds based on in situ observations. The reason for the wide spread of entrainment rate is that the observed clouds are affected by entrainment mixing processes to different extents, which is verified by the relationships between the entrainment rate and cloud microphysics/dynamics. The entrainment rate is negatively correlated with liquid water content and cloud droplet number concentration due to the dilution and evaporation in entrainment mixing processes. The entrainment rate is positively correlated with relative dispersion (i.e., ratio of standard deviation to mean value) of liquid water content and droplet size distributions, consistent with the theoretical expectation that entrainment mixing processes are responsible for microphysics fluctuations and spectral broadening. The entrainment rate is negatively correlated with vertical velocity and dissipation rate because entrainment

  5. 42 CFR 84.182 - Exhalation valve leakage test; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Exhalation valve leakage test; minimum requirements...-Powered Air-Purifying Particulate Respirators § 84.182 Exhalation valve leakage test; minimum requirements... height while in a normal operating position. (b) Leakage between the valve and valve seat shall...

  6. On the accuracy of the rate coefficients used in plasma fluid models for breakdown in air

    NASA Astrophysics Data System (ADS)

    Kourtzanidis, Konstantinos; Raja, Laxminarayan L.

    2016-07-01

    The electrical breakdown of air depends on the balance between creation and loss of charged particles. In fluid models, datasets of the rate coefficients used are obtained either from fits to experimental data or by solutions of the Boltzmann equation. Here, we study the accuracy of the commonly used models for ionization and attachment frequencies and their impact on the prediction of the breakdown threshold for air. We show that large errors can occur depending on the model and propose the most accurate dataset available for modeling of air breakdown phenomena.

  7. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  8. Long-term dynamics of death rates of emphysema, asthma, and pneumonia and improving air quality

    PubMed Central

    Kravchenko, Julia; Akushevich, Igor; Abernethy, Amy P; Holman, Sheila; Ross, William G; Lyerly, H Kim

    2014-01-01

    Background The respiratory tract is a major target of exposure to air pollutants, and respiratory diseases are associated with both short- and long-term exposures. We hypothesized that improved air quality in North Carolina was associated with reduced rates of death from respiratory diseases in local populations. Materials and methods We analyzed the trends of emphysema, asthma, and pneumonia mortality and changes of the levels of ozone, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and particulate matters (PM2.5 and PM10) using monthly data measurements from air-monitoring stations in North Carolina in 1993–2010. The log-linear model was used to evaluate associations between air-pollutant levels and age-adjusted death rates (per 100,000 of population) calculated for 5-year age-groups and for standard 2000 North Carolina population. The studied associations were adjusted by age group-specific smoking prevalence and seasonal fluctuations of disease-specific respiratory deaths. Results Decline in emphysema deaths was associated with decreasing levels of SO2 and CO in the air, decline in asthma deaths–with lower SO2, CO, and PM10 levels, and decline in pneumonia deaths–with lower levels of SO2. Sensitivity analyses were performed to study potential effects of the change from International Classification of Diseases (ICD)-9 to ICD-10 codes, the effects of air pollutants on mortality during summer and winter, the impact of approach when only the underlying causes of deaths were used, and when mortality and air-quality data were analyzed on the county level. In each case, the results of sensitivity analyses demonstrated stability. The importance of analysis of pneumonia as an underlying cause of death was also highlighted. Conclusion Significant associations were observed between decreasing death rates of emphysema, asthma, and pneumonia and decreases in levels of ambient air pollutants in North Carolina. PMID:25018627

  9. Experiments probing the influence of air exchange rates on secondary organic aerosols derived from indoor chemistry

    NASA Astrophysics Data System (ADS)

    Weschler, Charles J.; Shields, Helen C.

    Reactions between ozone and terpenes have been shown to increase the concentrations of submicron particles in indoor settings. The present study was designed to examine the influence of air exchange rates on the concentrations of these secondary organic aerosols as well as on the evolution of their particle size distributions. The experiments were performed in a manipulated office setting containing a constant source of d-limonene and an ozone generator that was remotely turned "on" or "off" at 6 h intervals. The particle number concentrations were monitored using an optical particle counter with eight-channels ranging from 0.1-0.2 to>2.0 μm diameter. The air exchange rates during the experiments were either high (working hours) or low (non-working hours) and ranged from 1.6 to>12 h -1, with intermediate exchange rates. Given the emission rates of ozone and d-limonene used in these studies, at an air exchange rate of 1.6 h -1 particle number concentration in the 0.1-0.2 μm size-range peaked 1.2 h after the ozone generator was switched on. In the ensuing 4.8 h particle counts increased in successive size-ranges up to the 0.5-0.7 μm diameter range. At higher air exchange rates, the resulting concentrations of total particles and particle mass (calculated from particle counts) were smaller, and at exchange rates exceeding 12 h -1, no excess particle formation was detectable with the instrument used in this study. Particle size evolved through accretion and, in some cases, coagulation. There was evidence for coagulation among particles in the smallest size-range at low air exchange rates (high particle concentrations) but no evidence of coagulation was apparent at higher air exchange rates (lower particle concentrations). At higher air exchange rates the particle count or size distributions were shifted towards smaller particle diameters and less time was required to achieve the maximum concentration in each of the size-ranges where discernable particle growth

  10. Duct leakage impacts on VAV system performance in California large commercial buildings

    SciTech Connect

    Wray, Craig P.; Matson, Nance E.

    2003-10-01

    The purpose of this study is to evaluate the variability of duct leakage impacts on air distribution system performance for typical large commercial buildings in California. Specifically, a hybrid DOE-2/TRNSYS sequential simulation approach was used to model the energy use of a low-pressure terminal-reheat variable-air-volume (VAV) HVAC system with six duct leakage configurations (tight to leaky) in nine prototypical large office buildings (representing three construction eras in three California climates where these types of buildings are common). Combined fan power for the variable-speed-controlled supply and return fans at design conditions was assumed to be 0.8 W/cfm. Based on our analyses of the 54 simulation cases, the increase in annual fan energy is estimated to be 40 to 50% for a system with a total leakage of 19% at design conditions compared to a tight system with 5% leakage. Annual cooling plant energy also increases by about 7 to 10%, but reheat energy decreases (about 3 to 10%). In combination, the increase in total annual HVAC site energy is 2 to 14%. The total HVAC site energy use includes supply and return fan electricity consumption, chiller and cooling tower electricity consumption, boiler electricity consumption, and boiler natural gas consumption. Using year 2000 average commercial sector energy prices for California ($0.0986/kWh and $7.71/Million Btu), the energy increases result in 9 to 18% ($7,400 to $9,500) increases in HVAC system annual operating costs. Normalized by duct surface area, the increases in annual operating costs are 0.14 to 0.18 $/ft{sup 2}. Using a suggested one-time duct sealing cost of $0.20 per square foot of duct surface area, these results indicate that sealing leaky ducts in VAV systems has a simple payback period of about 1.3 years. Even with total leakage rates as low as 10%, duct sealing is still cost effective. This suggests that duct sealing should be considered at least for VAV systems with 10% or more total duct

  11. Attenuation effects on the kerma rates in air after cesium depositions on grasslands.

    PubMed

    Jacob, P; Meckbach, R; Paretzke, H G; Likhtarev, I; Los, I; Kovgan, L; Komarikov, I

    1994-01-01

    Since the reactor accident of Chernobyl, cesium depth profiles and nuclide-specific kerma rates in air have been determined for various grassland sites in south Bavaria and in Ukraine. The sites are described by soil characteristics, annual precipitation, distance from release point, mode of deposition, and activity per unit area. The effects of surface roughness and migration of cesium into the soil on the kerma rate in air over grasslands was determined by two methods. The kerma rates in air obtained by the evaluations of in situ gamma-ray spectrometry results and of measured activity distributions in the soil showed only negligible differences for the observation period of 6 years after deposition. For the sites in Ukraine the kerma rate in air per activity per unit area was found to be systematically 40% higher than in Bavaria. The results from Bavaria on the attenuation of the kerma rate and a data set, including experiences from the weapons test fallout, are analytically approximated as a function of time up to 25 years after deposition. PMID:7809371

  12. Measurement of air exchange rates in residential and commercial buildings in the northwest: techniques and results

    SciTech Connect

    Parker, G.B.

    1985-04-01

    In a study of air exchange rates in commercial and residential buildings, several techniques were employed to measure the air exchange: analysis of sulfur hexafluoride tracer gas decay using a portable gas chromatograph; analysis of carbon monoxide decay using a continuous infrared analyzer; analysis of nitrogen oxides decay using a continuous oxides of nitrogen analyzer; and analysis of perfluorocarbon tracer (PFT) gas using a programmable automatic sampler, and a passive capillary tube sampler. Using sulfur hexafluoride tracer gas with real-time chromatography was the most labor-intensive method, requiring constant attention for several hours; whereas, analyzing the decay of PFT tracer gas using small capillary tubes required little setup time and virtually no attention. However, the analysis of tracer gas captured by the capillary tubes was difficult and was performed using special analysis equipment. The air exchange rate measured in the commercial buildings ranged from 5 to 0.04 air changes per hour (ACH) depending on the type of heating, ventilation, and air conditioning (HVAC) system. Air exchange in the residential structures ranged from about 1 ACH to about 0.3 ACH. 6 refs., 5 tabs., 3 figs.

  13. Contribution of Climate and Air Pollution to Variation in Coronary Heart Disease Mortality Rates in England

    PubMed Central

    Scarborough, Peter; Allender, Steven; Rayner, Mike; Goldacre, Michael

    2012-01-01

    There are substantial geographic variations in coronary heart disease (CHD) mortality rates in England that may in part be due to differences in climate and air pollution. An ecological cross-sectional multi-level analysis of male and female CHD mortality rates in all wards in England (1999–2004) was conducted to estimate the relative strength of the association between CHD mortality rates and three aspects of the physical environment - temperature, hours of sunshine and air quality. Models were adjusted for deprivation, an index measuring the healthiness of the lifestyle of populations, and urbanicity. In the fully adjusted model, air quality was not significantly associated with CHD mortality rates, but temperature and sunshine were both significantly negatively associated (p<0.05), suggesting that CHD mortality rates were higher in areas with lower average temperature and hours of sunshine. After adjustment for the unhealthy lifestyle of populations and deprivation, the climate variables explained at least 15% of large scale variation in CHD mortality rates. The results suggest that the climate has a small but significant independent association with CHD mortality rates in England. PMID:22427884

  14. USAF bioenvironmental noise data handbook. Volume 168: MB-3 tester, pressurized cabin leakage, aircraft

    NASA Astrophysics Data System (ADS)

    Rau, T. H.

    1982-06-01

    The MB-3 Tester is an electric motor-driven cabin leakage tester designed to furnish pressurized air to the aircraft at controlled pressures and temperatures during ground pressurization of aircraft cockpits and pressurized compartments. This report provides measured data defining the bioacoustic environments produced by this unit operating at a normal rated/load condition. Near-field data are reported for 37 locations in a wide variety of physical and psychoacoustic measures: overall and band sound pressure levels, C-weighted and A-weighted sound levels, preferred speech interference level, perceived noise level, and limiting times for total daily exposure of personnel with and without standard Air Force ear protectors.

  15. EFFECT OF AIR-POLLUTION CONTROL ON DEATH RATES IN DUBLIN, IRELAND: AN INTERVENTION STUDY. (R827353C006)

    EPA Science Inventory

    Background Particulate air pollution episodes have been associated with increased daily death. However, there is little direct evidence that diminished particulate air pollution concentrations would lead to reductions in death rates. We assessed the effect of ...

  16. Geologic Carbon Sequestration: Leakage Potential and Policy Implications

    NASA Astrophysics Data System (ADS)

    Bielicki, J. M.; Peters, C. A.; Fitts, J. P.; Wilson, E. J.

    2014-12-01

    The geologic reservoirs that could be used for long-term sequestration of carbon dioxide (CO2) may have natural or manmade pathways that allow injected CO2, or the brine it displaces, to leak into overlying formations. Using a basin-scale leakage estimation model, we investigated the geophysical parameters that govern this leakage, and the resulting accumulations of leaked fluids in overlying formations. The results are discussed in the context of two polices aimed at governing long-term sequestration and protecting groundwater: the U.S. DOE guideline for storage permanence and the U.S. EPA UIC Program Class VI Rule. For a case study of CO2 injection into the Mt. Simon sandstone in the Michigan sedimentary basin, we showed that (1) the U.S. DOE guideline would allow for more leakage from larger injection projects than for smaller ones; (2) leakage amounts are determined mostly by well leakage permeability rather than by variation in formation permeabilities; (3) numerous leaking wells with anomalously high leakage permeabilities are necessary in order to achieve substantial leakage rates; (4) leakage can reach potable groundwater but intervening stratigraphic traps reduce the amount to be multiple orders of magnitude less than the leakage out of the reservoir, and (5) this leakage can reduce the Area of Review that is defined by the U.S. EPA as the area within which leakage can threaten groundwater. In summary, leakage that exceeds the U.S. DOE storage permanence goal would occur only under extreme conditions, the amount that reaches shallow potable groundwater may be inconsequential from a pollution standpoint, and leakage may be beneficial. Future federal policies should be harmonized to achieve the dual goals of protecting groundwater while allowing for adaptive management that incorporates uncertainties and imperfections inherent in geologic reservoirs.

  17. THE EFFECT OF OPENING WINDOWS ON AIR CHANGE RATES IN TWO HOMES

    EPA Science Inventory

    Over 300 air change rate experiments were completed in two occupied residences: a two-story detached house in Redwood City, CA and a three-story townhouse in Reston, VA. A continuous monitor was used to measure the decay of sulfur hexafluoride tracer gas over periods of 1 to 1...

  18. Spray droplet sizes with additives discharged from an air-assisted variable-rate nozzle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding droplet size distributions is essential to achieve constant spray quality for real-time variable-rate sprayers that synchronize spray outputs with canopy structures. Droplet sizes were measured for a custom-designed, air-assisted, five-port nozzle coupled with a pulse width modulated (...

  19. Spray deposition inside tree canopies from a newly developed variable-rate air assisted sprayer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conventional spray applications in orchards and ornamental nurseries are not target-oriented, resulting in significant waste of pesticides and contamination of the environment. To address this problem, a variable-rate air-assisted sprayer implementing laser scanning technology was developed to apply...

  20. Atmospheric leakage and condensate production in NASA's biomass production chamber. Effect of diurnal temperature cycles

    NASA Technical Reports Server (NTRS)

    Wheeler, Raymond M.; Drese, John H.; Sager, John C.

    1991-01-01

    A series of tests were conducted to monitor atmospheric leakage rate and condensate production in NASA's Biomass Production Chamber (BPC). Water was circulated through the 64 plant culture trays inside the chamber during the tests but no plants were present. Environmental conditions were set to a 12-hr photoperiod with either a matching 26 C (light)/20 C (dark) thermoperiod, or a constant 23 C temperature. Leakage, as determined by carbon dioxide decay rates, averaged about 9.8 percent for the 26 C/20 C regime and 7.3 percent for the constant 23 C regime. Increasing the temperature from 20 C to 26 C caused a temporary increase in pressure (up to 0.5 kPa) relative to ambient, while decreasing the temperature caused a temporary decrease in pressure of similar magnitude. Little pressure change was observed during transition between 23 C (light) and 23 C (dark). The lack of large pressure events under isothermal conditions may explain the lower leakage rate observed. When only the plant support inserts were placed in the culture trays, condensate production averaged about 37 liters per day. Placing acrylic germination covers over the tops of culture trays reduced condensate production to about 7 liters per day. During both tests, condensate production from the lower air handling system was 60 to 70 percent greater than from the upper system, suggesting imbalances exist in chilled and hot water flows for the two air handling systems. Results indicate that atmospheric leakage rates are sufficiently low to measure CO2 exchange rates by plants and the accumulation of certain volatile contaminants (e.g., ethylene). Control system changes are recommended in order to balance operational differences (e.g., humidity and temperature) between the two halves of the chamber.

  1. Electrical leakage detection circuit

    DOEpatents

    Wild, Arthur

    2006-09-05

    A method is provided for detecting electrical leakage between a power supply and a frame of a vehicle or machine. The disclosed method includes coupling a first capacitor between a frame and a first terminal of a power supply for a predetermined period of time. The current flowing between the frame and the first capacitor is limited to a predetermined current limit. It is determined whether the voltage across the first capacitor exceeds a threshold voltage. A first output signal is provided when the voltage across the capacitor exceeds the threshold voltage.

  2. Evaluation of the indoor air quality minimum ventilation rate procedure for use in California retail buildings.

    PubMed

    Dutton, S M; Mendell, M J; Chan, W R; Barrios, M; Sidheswaran, M A; Sullivan, D P; Eliseeva, E A; Fisk, W J

    2015-02-01

    This research assesses benefits of adding to California Title-24 ventilation rate (VR) standards a performance-based option, similar to the American Society of Heating, Refrigerating, and Air Conditioning Engineers 'Indoor Air Quality Procedure' (IAQP) for retail spaces. Ventilation rates and concentrations of contaminants of concern (CoC) were measured in 13 stores. Mass balance models were used to estimate 'IAQP-based' VRs that would maintain concentrations of all CoCs below health- or odor-based reference concentration limits. An intervention study in a 'big box' store assessed how the current VR, the Title 24-prescribed VR, and the IAQP-based VR (0.24, 0.69, and 1.51 air changes per hour) influenced measured IAQ and perceived of IAQ. Neither current VRs nor Title 24-prescribed VRs would maintain all CoCs below reference limits in 12 of 13 stores. In the big box store, the IAQP-based VR kept all CoCs below limits. More than 80% of subjects reported acceptable air quality at all three VRs. In 11 of 13 buildings, saving energy through lower VRs while maintaining acceptable IAQ would require source reduction or gas-phase air cleaning for CoCs. In only one of the 13 retail stores surveyed, application of the IAQP would have allowed reduced VRs without additional contaminant-reduction strategies. PMID:24809924

  3. Relationship between recycling rate and air pollution: Waste management in the state of Massachusetts

    SciTech Connect

    Giovanis, Eleftherios

    2015-06-15

    Highlights: • This study examines the relationship between recycling rate of solid waste and air pollution. • Fixed effects Stochastic Frontier Analysis model with panel data are employed. • The case study is a waste municipality survey in the state of Massachusetts during 2009–2012. • The findings support that a negative relationship between air pollution and recycling. - Abstract: This study examines the relationship between recycling rate of solid waste and air pollution using data from a waste municipality survey in the state of Massachusetts during the period 2009–2012. Two econometric approaches are applied. The first approach is a fixed effects model, while the second is a Stochastic Frontier Analysis (SFA) with fixed effects model. The advantage of the first approach is the ability of controlling for stable time invariant characteristics of the municipalities, thereby eliminating potentially large sources of bias. The second approach is applied in order to estimate the technical efficiency and rank of each municipality accordingly. The regressions control for various demographic, economic and recycling services, such as income per capita, population density, unemployment, trash services, Pay-as-you-throw (PAYT) program and meteorological data. The findings support that a negative relationship between particulate particles in the air 2.5 μm or less in size (PM{sub 2.5}) and recycling rate is presented. In addition, the pollution is increased with increases on income per capita up to $23,000–$26,000, while after this point income contributes positively on air quality. Finally, based on the efficiency derived by the Stochastic Frontier Analysis (SFA) model, the municipalities which provide both drop off and curbside services for trash, food and yard waste and the PAYT program present better performance regarding the air quality.

  4. Effect of outside air ventilation rate on VOC concentrations and emissions in a call center

    SciTech Connect

    Hodgson, A.T.; Faulkner, D.; Sullivan, D.P.; DiBartolomeo, D.L.; Russell, M.L.; Fisk, W.J.

    2002-01-01

    A study of the relationship between outside air ventilation rate and concentrations of VOCs generated indoors was conducted in a call center. Ventilation rates were manipulated in the building's four air handling units (AHUs). Concentrations of VOCs in the AHU returns were measured on 7 days during a 13-week period. Indoor minus outdoor concentrations and emission factors were calculated. The emission factor data was subjected to principal component analysis to identify groups of co-varying compounds based on source type. One vector represented emissions of solvents from cleaning products. Another vector identified occupant sources. Direct relationships between ventilation rate and concentrations were not observed for most of the abundant VOCs. This result emphasizes the importance of source control measures for limiting VOC concentrations in buildings.

  5. The measurement of water vapour transfer rate through clothing system with air gap between layers

    NASA Astrophysics Data System (ADS)

    Oh, Ae-Gyeong

    2008-02-01

    The experiments described in this paper are designed to test the water vapour transfer rates through outdoor clothing system with air gap between layers under conditions more closely actual wear. It was adopted distance of 5 mm to ensure no disturbance of the air gap thickness between layers throughout the measurement period with all fabrics. The results have indicated that the water vapour transfer rates of clothing system decrease very slightly with time, it is shown that they approached nearly equilibrium state throughout the experiment. It is revealed that the water vapour transfer rates of the clothing system were ordered into groups determined by the type of waterproof breathable fabric as a shell layer being ordered.

  6. Eccentricity effects on leakage of a brush seal at low speeds

    NASA Technical Reports Server (NTRS)

    Schlumberger, Julie A.; Proctor, Margaret P.; Hendricks, Robert C.

    1991-01-01

    The effects of eccentricity on brush seal leakage at low rotational speeds were investigated. Included are the leakage results for ambient temperature air and nearly saturated streams at three different rotor eccentricities at both 0 and 400 rpm. A brush seal with a nominal bore diameter of 13.647 cm. (5.3730 in.) was used. It had a radial concentric interference of 0.071 cm (0.0028 in.) and a fence height of 0.0927 cm (0.0365 in.). There were 1060 bristles per centimeter of circumference (2690 bristles per inch of circumference). Rotor eccentricities of 0.003, 0.010, 0.038, and 0.043 cm (0.001, 0.004, 0.015, and 0.017 in.) were achieved by using bushings with different offsets. The results were compared with an annular seal model (FLOWCAL) for air and to a standard labyrinth seal model for steam. The annular seal model was also compared with a bulk flow model of a concentric brush seal in air. Large eccentricities did not damage the brush seals or their Haynes 25 bristles. However, the 304 stainless steel rotor did not show wear, indicating a harder surface is needed. Only the stream data showed hysteresis and were affected by shaft rotation. The brush seal had lower leakage rates than those predicted for comparable annular and labyrinth seals (conventional) because of the large clearances those seals require to accommodate large shaft excursions.

  7. Rate constants for chemical reactions in high-temperature nonequilibrium air

    NASA Technical Reports Server (NTRS)

    Jaffe, R. L.

    1986-01-01

    In the nonequilibrium atmospheric chemistry regime that will be encountered by the proposed Aeroassisted Orbital Transfer Vehicle in the upper atmosphere, where air density is too low for thermal and chemical equilibrium to be maintained, the detailed high temperature air chemistry plays a critical role in defining radiative and convective heating loads. Although vibrational and electronic temperatures remain low (less than 15,000 K), rotational and translational temperatures may reach 50,000 K. Attention is presently given to the effects of multiple temperatures on the magnitudes of various chemical reaction rate constants, for the cases of both bimolecular exchange reactions and collisional excitation and dissociation reactions.

  8. Measuring Infiltration Rates in Homes as a Basis for Understanding Indoor Air Quality

    NASA Astrophysics Data System (ADS)

    Jerz, G. G.; Lamb, B. K.; Pressley, S. N.; O'Keeffe, P.; Fuchs, M.; Kirk, M.

    2015-12-01

    Infiltration rates, or the rate of air exchange, of houses are important to understand because ventilation can be a dominate factor in determining indoor air quality. There are chemicals that are emitted from surfaces or point sources inside the home which are harmful to humans; these chemicals come from various objects including furniture, cleaning supplies, building materials, gas stoves, and the surrounding environment. The use of proper ventilation to cycle cleaner outdoor air into the house can be crucial for maintaining healthy living conditions in the home. At the same time, there can also be outdoor pollutants which infiltrate the house and contribute to poor indoor air quality. In either case, it is important to determine infiltration rates as a function of outdoor weather conditions, the house structure properties and indoor heating and cooling systems. In this work, the objective is to measure ventilation rates using periodic releases of a tracer gas and measuring how quickly the tracer concentration decays. CO2 will be used as the tracer gas because it is inert and harmless at low levels. An Arduino timer is connected to a release valve which controls the release of 9.00 SLPM of CO2 into the uptake vent within the test home. CO2 will be released until there is at least a 200 to 300 ppm increase above ambient indoor levels. Computers with CO2 sensors and temperature/pressure sensors attached will be used to record data from different locations within the home which will continuously record data up to a week. The results from these periodic ventilation measurements will be analyzed with respect to outdoor wind and temperature conditions and house structure properties. The data will be used to evaluate an established indoor air quality model.

  9. Age of air and heating rates: comparison of ERA-40 with ERA-Interim

    NASA Astrophysics Data System (ADS)

    Legras, B.; Fueglistaler, S.

    2009-04-01

    The age of air in the stratosphere is often used as a test for the good representation of the Brewer-Dobson circulation by atmospheric models. This is a critical requirement to modelize the distribution of long-lived species in chemical models. It is often advocated that using heating rates for vertical transport in the stratosphere performs better that standard analysed velocities from weather centers. This work is based on an extensive comparison of the age of air using 5 years of heating rates from the ERA-40 reanalysis and from the new ERA-interim reanalysis built with 4D-Var assimilation. The ERA-40 exhibits both too young ages with analyzed velocities and too old ages with heating rates. The reason for too young ages is spurious transport associated with too noisy wind, as a result of 3D-Var assimilation. Heating rates provide a much less noisy meridional circulation and preserve transport barriers and polar vortex confinement. However, excessive cooling near 30 hPa in the tropics blocks the ascending motion within the tropical pipe over extended periods of time inducing very old ages. This effect is usually corrected by an empirical correction which can exceed in some regions the calculated heating rate in magnitude, with opposite sign. We relate this correction to the assimilation temperature increment that is required to compensate the bias of the model, notably the excessive negative heat transport due to the noisy vertical velocities and the lack of mass conservation in the isentropic frame. The new ERA-interim exhibits much reduced noise in the vertical velocity and is ten times less diffusive than the ERA-40 in the tropics. Age of air is then found to be slightly older than given by the observations. The biases in the heating rate have also been considerably reduced with respect to ERA-40 and the assimilation increment is now only a fraction of the heating rate. The age of air is in fairly good aggreement with the observations at 20 km and higher

  10. Gaseous hydrogen leakage optical fibre detection system

    NASA Astrophysics Data System (ADS)

    Trouillet, Alain; Veillas, Colette; Sigronde, E.; Gagnaire, Henri; Clement, Michel

    2004-06-01

    Liquid hydrogen has been intensively used in aerospace applications during the past forty years and is of great interest for fuel cells technologies and future automotive applications. Following upon major explosive risks due to the use of hydrogen in air, previous studies were carried out in our laboratory in order to develop optical fiber sensors for the detection of hydrogen leakage. This communication is aimed towards a prototype optical fiber system designed for the detection of gaseous hydrogen leakage near the conecting flanges of the liquid hydrogen pipes on the test bench of the engine Vulcain of the rocket ARIANE V. Depending on the configuration, the prototype sensor provides a two-level alarm signal and the detection of gaseous hydrogen leakage is possible for concentrations lower than the lower explosive limit in air (between 0.1 and 4%) with alarm response times lower than 10 seconds in a wide range of temperatures between -35°C and 300°C. The sensing principle based on palladium-hydrogen interaction is presented as well as the detection system composed of an optical fiber probe and an optoelectronic device.

  11. Relationship between recycling rate and air pollution: Waste management in the state of Massachusetts.

    PubMed

    Giovanis, Eleftherios

    2015-06-01

    This study examines the relationship between recycling rate of solid waste and air pollution using data from a waste municipality survey in the state of Massachusetts during the period 2009-2012. Two econometric approaches are applied. The first approach is a fixed effects model, while the second is a Stochastic Frontier Analysis (SFA) with fixed effects model. The advantage of the first approach is the ability of controlling for stable time invariant characteristics of the municipalities, thereby eliminating potentially large sources of bias. The second approach is applied in order to estimate the technical efficiency and rank of each municipality accordingly. The regressions control for various demographic, economic and recycling services, such as income per capita, population density, unemployment, trash services, Pay-as-you-throw (PAYT) program and meteorological data. The findings support that a negative relationship between particulate particles in the air 2.5 μm or less in size (PM2.5) and recycling rate is presented. In addition, the pollution is increased with increases on income per capita up to $23,000-$26,000, while after this point income contributes positively on air quality. Finally, based on the efficiency derived by the Stochastic Frontier Analysis (SFA) model, the municipalities which provide both drop off and curbside services for trash, food and yard waste and the PAYT program present better performance regarding the air quality. PMID:25827258

  12. Smoking, air pollution, and the high rates of lung cancer in Shenyang, China

    SciTech Connect

    Xu, Z.Y.; Blot, W.J.; Xiao, H.P.; Wu, A.; Feng, Y.P.; Stone, B.J.; Sun, J.; Ershow, A.G.; Henderson, B.E.; Fraumeni, J.F. Jr. )

    1989-12-06

    A case-control study involving interviews with 1,249 patients with lung cancer and 1,345 population-based controls was conducted in Shenyang, an industrial city in northeastern China, where mortality rates are high among men and women. Cigarette smoking was found to be the principal cause of lung cancer in this population, accounting for 55% of the lung cancers in males and 37% in females. The attributable risk percentage among females is high compared to elsewhere in China, largely because of a higher prevalence of smoking among women. After adjustment for smoking, there were also significant increases in lung cancer risk associated with several measures of exposure to air pollutants. Risks were twice as high among those who reported smoky outdoor environments, and increased in proportion to years of sleeping on beds heated by coal-burning stoves (kang), and to an overall index of indoor air pollution. Threefold increases in lung cancer risk were found among men who worked in the nonferrous smelting industry, where heavy exposures to inorganic arsenic have been reported. The associations with both smoking and indoor air pollution were stronger for squamous cell and small cell carcinomas than for adenocarcinoma of the lung. Risks due to smoking or air pollution were not greatly altered by adjustment for consumption of fresh vegetables or sources of beta carotene or retinol, prior chronic lung diseases, or education level. The findings suggest that smoking and environmental pollution combine to account for the elevated rates of lung cancer mortality in Shenyang.

  13. A Subgrid Model for Predicting Air Entrainment Rates in Bubbly Flows

    NASA Astrophysics Data System (ADS)

    Ma, Jingsen; Oberai, Assad A.; Drew, Donald E.; Lahey, Richard T., Jr.; Moraga, Francisco J.

    2008-11-01

    In this talk we present a fairly simple subgrid air entrainment model that accurately predicts the rate of air entrainment, which is critical in simulating multiphase (air/water) flows. The derivation of this model begins by assuming that a thin sheet of air is carried into the water by the inertia of the liquid at the free surface. A momentum balance on the entrained gas layer results in an expression for the entrained volumetric gas flow rate, in terms of the local liquid velocity, gas viscosity etc., which are readily available from a multiphase RANS-type simulation. This model has been validated against extensive experimental data on both plunging jets and hydraulic jumps over a wide range of liquid velocities. It was implemented in a two-fluid computational fluid dynamics code (CFDShipM) to be used to predict the void fraction distribution underneath a plunging liquid jet at different depths and jet velocities. The results were found to match the experimental observations very well. The application of this model to more challenging problems, including hydraulic jumps and full-scale ship simulations, is currently underway.

  14. Mathematical Modeling of Radiocesium Migration and Air Dose Rate Changes in Eastern Fukushima Prefecture

    NASA Astrophysics Data System (ADS)

    Kitamura, A.; Sakuma, K.; Kurikami, H.; Malins, A.; Okumura, M.; Itakura, M.; Yamada, S.; Machida, M.

    2015-12-01

    Radioactive cesium that was deposited over Fukushima Prefecture after the accident at the Fukushima Daiichi nuclear power plant station is one of the major concerns regarding health physics today. Its migration is primarily by soil erosion and sediment transport within surface water during times of heavy rainfall and flooding. In order to predict the future distribution of radioactive cesium and resulting air dose rate at any location in Fukushima, we have integrated a number of mathematical models covering different time and spatial scales. In this presentation we report our overall scheme of prediction starting from sediment and radioactive cesium movement and resulting long term air dose rate changes. Specifically, we present simulation results of sediment movement and radioactive cesium migration using semi-empirical and physics based watershed models, and that of sediment and radioactive cesium behavior in a dam reservoir using one and two dimensional river simulation models. The model's results are compared with ongoing field monitoring.

  15. Risk of sick leave associated with outdoor air supply rate, humidification, and occupant complaints.

    PubMed

    Milton, D K; Glencross, P M; Walters, M D

    2000-12-01

    We analyzed 1994 sick leave for 3,720 hourly employees of a large Massachusetts manufacturer, in 40 buildings with 115 independently ventilated work areas. Corporate records identified building characteristics and IEQ complaints. We rated ventilation as moderate (approximately 25 cfm/person, 12 ls-1) or high (approximately 50 cfm/person, 24 ls-1) outdoor air supply based on knowledge of ventilation systems and CO2 measurements on a subset of work areas, and used Poisson regression to analyze sick leave controlled for age, gender, seniority, hours of non-illness absence, shift, ethnicity, crowding, and type of job (office, technical, or manufacturing worker). We found consistent associations of increased sick leave with lower levels of outdoor air supply and IEQ complaints. Among office workers, the relative risk for short-term sick leave was 1.53 (95% confidence 1.22-1.92) with lower ventilation, and 1.52 (1.18-1.97) in areas with IEQ complaints. The effect of ventilation was independent of IEQ complaints and among those exposed to lower outdoor air supply rates the attributable risk of short-term sick leave was 35%. The cost of sick leave attributable to ventilation at current recommended rates was estimated as $480 per employee per year at Polaroid. These findings suggest that net savings of $400 per employee per year may be obtained with increased ventilation. Thus, currently recommended levels of outdoor air supply may be associated with significant morbidity, and lost productivity on a national scale could be as much as $22.8 billion per year. Additional studies of IEQ impacts on productivity and sick leave, and the mechanisms underlying the apparent association are needed. PMID:11089326

  16. Endoscopic Treatment of Stump Leakage Related to the Ileal Conduit

    PubMed Central

    Odemis, Bulent; Oztas, Erkin; Akpinar, Muhammet Yener; Olcucuoglu, Erkan; Kayacetin, Ertugrul

    2016-01-01

    Abstract Background: Ileal conduit with leakage from either the anastomotic site or the stump is associated with high morbidity and mortality rates. The standard treatment of stump leakage is surgery. Case Presentation: A 60-year-old male patient was admitted to our hospital with complaint of hematuria and bladder carcinoma was diagnosed. After performing radical cystectomy and ileal conduit, he developed fever with abdominal pain within the first week of surgery. Stump leakage was diagnosed by endoscopic examination performed through a gastroscope. After two over-the-scope clips (OTSCs) were applied to the stump, vinyl mesh was inserted into the space between the OTSCs. Later, cyanoacrylat and lipiodol were repelled on the OTSCs and vinyl mesh. Subsequently, stump leakage was resolved. Conclusion: This is the first case of stump leakage related to ileal conduit that has been treated endoscopically, according to the current literature. PMID:27579432

  17. Establishment of air kerma reference standard for low dose rate Cs-137 brachytherapy sources.

    PubMed

    Sharma, Sunil Dutt; Kumar, Sudhir; Srinivasan, P; Chourasiya, G

    2011-01-01

    A guarded cylindrical graphite ionization chamber of nominal volume 1000 cm3 was designed and fabricated for use as a reference standard for low-dose rate 137Cs brachytherapy sources. The air kerma calibration coefficient (N(K)) of this ionization chamber was estimated analytically using Burlin's general cavity theory, as well as by the Monte Carlo simulation and validated experimentally using Amersham CDCS-J-type 137Cs reference source. In the analytical method, the N(K) was calculated for 662 keV gamma rays of 137Cs brachytherapy source. In the Monte Carlo method, the geometry of the measurement setup and physics-related input data of the 137Cs source and the surrounding material were simulated using the Monte Carlo N-Particle code. The photon energy fluence was used to arrive at the reference air kerma rate (RAKR) using mass energy absorption coefficient. The energy deposition rates were used to simulate the value of charge rate in the ionization chamber, and the N(K) was determined. The analytical and Monte Carlo values of N(K) of the cylindrical graphite ionization chamber for 137Cs brachytherapy source are in agreement within 1.07%. The deviation of analytical and Monte Carlo values from experimental values of N(K) is 0.36% and 0.72%, respectively. This agreement validates the analytical value, and establishes this chamber as a reference standard for RAKR or AKS measurement of 137Cs brachytherapy sources. PMID:22089009

  18. Method and apparatus for measuring the rate at which air infiltrates into and out of buildings

    SciTech Connect

    Dempsey, J. C.

    1985-01-15

    Tracer emission sources which emit tracer gas at a predetermined constant known rate are distributed throughout a building. The preferred source is a small vessel containing a vaporous perfluorocarbon tracer (PFT) substance having a very small bore hole in the top through which the PFT vapor can escape. Time is permitted for the tracer gas to mix uniformly throughout the building and for its concentration to equilibrate with infiltrating air. The concentration of the tracer is then measured and compared to the known volume of air in the building to determine the infiltration rate. In the preferred mode, the concentration is integrated and measured by continuously sampling the tracer gas at a constant rate on activated charcoal adsorbent over a period of several weeks. The amount of tracer substance accumulated on the adsorbent at the end of the test is directly related to the average tracer gas concentration which existed in the building during the sampling period and it can therefore be used to calculate an average infiltration rate during that period.

  19. Modified perfluorocarbon tracer method for measuring effective multizone air exchange rates.

    PubMed

    Shinohara, Naohide; Kataoka, Toshiyuki; Takamine, Koichi; Butsugan, Michio; Nishijima, Hirokazu; Gamo, Masashi

    2010-09-01

    A modified procedure was developed for the measurement of the effective air exchange rate, which represents the relationship between the pollutants emitted from indoor sources and the residents' level of exposure, by placing the dosers of tracer gas at locations that resemble indoor emission sources. To measure the 24-h-average effective air exchange rates in future surveys based on this procedure, a low-cost, easy-to-use perfluorocarbon tracer (PFT) doser with a stable dosing rate was developed by using double glass vials, a needle, a polyethylene-sintered filter, and a diffusion tube. Carbon molecular sieve cartridges and carbon disulfide (CS₂) were used for passive sampling and extraction of the tracer gas, respectively. Recovery efficiencies, sampling rates, and lower detection limits for 24-h sampling of hexafluorobenzene, octafluorotoluene, and perfluoroallylbenzene were 40% ± 3%, 72% ± 5%, and 84% ± 6%; 10.5 ± 1.1, 14.4 ± 1.4, and 12.2 ± 0.49 mL min⁻¹; and 0.20, 0.17, and 0.26 μg m⁻³, respectively. PMID:20948928

  20. Whole house particle removal and clean air delivery rates for in-duct and portable ventilation systems.

    PubMed

    Macintosh, David L; Myatt, Theodore A; Ludwig, Jerry F; Baker, Brian J; Suh, Helen H; Spengler, John D

    2008-11-01

    A novel method for determining whole house particle removal and clean air delivery rates attributable to central and portable ventilation/air cleaning systems is described. The method is used to characterize total and air-cleaner-specific particle removal rates during operation of four in-duct air cleaners and two portable air-cleaning devices in a fully instrumented test home. Operation of in-duct and portable air cleaners typically increased particle removal rates over the baseline rates determined in the absence of operating a central fan or an indoor air cleaner. Removal rates of 0.3- to 0.5-microm particles ranged from 1.5 hr(-1) during operation of an in-duct, 5-in. pleated media filter to 7.2 hr(-1) for an in-duct electrostatic air cleaner in comparison to a baseline rate of 0 hr(-1) when the air handler was operating without a filter. Removal rates for total particulate matter less than 2.5 microm in aerodynamic diameter (PM2.5) mass concentrations were 0.5 hr(-1) under baseline conditions, 0.5 hr(-1) during operation of three portable ionic air cleaners, 1 hr(-1) for an in-duct 1-in. media filter, 2.4 hr(-1) for a single high-efficiency particle arrestance (HEPA) portable air cleaner, 4.6 hr(-1) for an in-duct 5-in. media filter, 4.7 hr(-1) during operation of five portable HEPA filters, 6.1 hr(-1) for a conventional in-duct electronic air cleaner, and 7.5 hr(-1) for a high efficiency in-duct electrostatic air cleaner. Corresponding whole house clean air delivery rates for PM2.5 attributable to the air cleaner independent of losses within the central ventilation system ranged from 2 m3/min for the conventional media filter to 32 m3/min for the high efficiency in-duct electrostatic device. Except for the portable ionic air cleaner, the devices considered here increased particle removal indoors over baseline deposition rates. PMID:19044163

  1. Distribution and variability of the 24-h average air exchange rates and interzonal flow rates in 26 Japanese residences in 5 seasons

    NASA Astrophysics Data System (ADS)

    Shinohara, Naohide; Kataoka, Toshiyuki; Takamine, Koichi; Gamo, Masashi

    2011-07-01

    In this study, to evaluate the distribution of air exchange rates in Japan, daily, seasonal, and inter-residence variabilities were determined as well as the air exchange rate itself. In addition, airflows among multiple zones were also evaluated. For this purpose, the 24 h average air exchange rates and interzonal air flow rates were measured using a passive perfluorocarbon tracer (PFT) method with three kinds of tracer gases for 1 week in three rooms of 26 Japanese residences over five seasons: summer and autumn of 2005, and winter, spring, and summer of 2006. During these seasons, the weekly average air exchange rates were found to be 1.6 ± 1.7, 0.58 ± 0.94, 0.61 ± 0.93, 1.2 ± 2.5, and 1.7 ± 1.8 h -1, respectively. Two-way repeated measure analysis of variance (ANOVA) revealed that the air exchange rates differed significantly with respect to the seasons, residences, and interaction of seasons and residences ( p < 0.01). In addition, the air exchange rates in both summers and spring were statistically higher than those in autumn and winter (Sheffe test, p < 0.01). According to the ANOVA, the percentage contribution of inter-residence variability, seasonal variability, interaction of seasonal and inter-residence variabilities, and daily variability to the total variability of the 24 h average air exchange rates in the present survey was 51%, 44%, 3.7%, and 1.0%, respectively.

  2. Duct Leakage Repeatability Testing

    SciTech Connect

    Walker, Iain; Sherman, Max

    2014-08-01

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

  3. LABORATORY EVALUATION OF THE DELTA Q TEST FOR DUCT LEAKAGE

    SciTech Connect

    ANDREWS,J.W.

    2003-05-01

    Using a residential-size duct system in a controlled laboratory setting, the repeatability and accuracy of the Delta Q test for air leakage in residential duct systems have been measured. More than 100 Delta Q tests were performed. These were compared with results using fan pressurization and also with results of a procedure (Delta Q Plus) that uses leakage hole-size information to select the leakage pressures to be used in the Delta Q algorithm. The average error in supply or return leakage for the fan-pressurization test was 6.4% of system fan flow. For the Delta Q test it was 3.4% of fan flow, while for Delta Q Plus it was 1.9% of fan flow.

  4. Neutrino Leakage and Supernova Explosion

    NASA Astrophysics Data System (ADS)

    Liao, Dao-Bing; Zhang, Miao-Jing; Li, Yan; Pan, Jiang-Hong; Chen, Xiu

    2015-04-01

    In the process of supernova explosion the leakage of neutrinos is very important. Adopting an one-dimensional spherically symmetrical model, and under the different neutrino leakage modes, the explosion processes of type II supernovae with masses of 12 M⊙, 14 M⊙, and 15 M⊙ are simulated numerically. The results indicate that all these different neutrino leakage modes have influences on the supernova collapse, shock propagation, and supernova explosion. The best values of the related parameters which are propitious for the type II supernova explosion are given. In addition, the impacts of the equation of state and the compression modulus on the simulated results are discussed.

  5. Evaluation of passive air sampler calibrations: Selection of sampling rates and implications for the measurement of persistent organic pollutants in air

    NASA Astrophysics Data System (ADS)

    Melymuk, Lisa; Robson, Matthew; Helm, Paul A.; Diamond, Miriam L.

    2011-04-01

    Polyurethane foam (PUF) passive air samplers (PAS) are a common and highly useful method of sampling persistent organic pollutants (POP) concentrations in air. PAS calibration is necessary to obtain reasonable and comparable semi-quantitative measures of air concentrations. Various methods are found in the literature concerning PAS calibration. 35 studies on PAS use and calibration are examined here, in conjunction with a study involving 10 PAS deployed concurrently in outdoor air with a low-volume air sampler in order to measure the sampling rates of PUF-PAS for polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic musks (PCMs), and polycyclic aromatic hydrocarbons (PAHs). Based on this analysis it is recommended that (1) PAS should be assumed to represent bulk rather than gas-phase compound concentrations due to the sampling of particle-bound compounds, (2) calibration of PAS sampling rates is more accurately achieved using an active low-volume air sampler rather than depuration compounds since the former measures gas- and particle-phase compounds and does so continuously over the deployment period of the PAS, and (3) homolog-specific sampling rates based on KOA groupings be used in preference to compound/congener-specific or single sampling rates.

  6. Ambient temperature, air pollution, and heart rate variability in an aging population.

    PubMed

    Ren, Cizao; O'Neill, Marie S; Park, Sung Kyun; Sparrow, David; Vokonas, Pantel; Schwartz, Joel

    2011-05-01

    Studies show that ambient temperature and air pollution are associated with cardiovascular disease and that they may interact to affect cardiovascular events. However, few epidemiologic studies have examined mechanisms through which ambient temperature may influence cardiovascular function. The authors examined whether temperature was associated with heart rate variability (HRV) in a Boston, Massachusetts, study population and whether such associations were modified by ambient air pollution concentrations. The population was a cohort of 694 older men examined between 2000 and 2008. The authors fitted a mixed model to examine associations between temperature and air pollution and their interactions with repeated HRV measurements, adjusting for covariates selected a priori on the basis of their previous studies. Results showed that higher ambient temperature was associated with decreases in HRV measures (standard deviation of normal-to-normal intervals, low-frequency power, and high-frequency power) during the warm season but not during the cold season. These warm-season associations were significantly greater when ambient ozone levels were higher (>22.3 ppb) but did not differ according to levels of ambient fine (≤2.5 μm) particulate matter. The authors conclude that temperature and ozone, exposures to both of which are expected to increase with climate change, might act together to worsen cardiovascular health and/or precipitate cardiovascular events via autonomic nervous system dysfunction. PMID:21385834

  7. Measuring and modeling air exchange rates inside taxi cabs in Los Angeles, California

    NASA Astrophysics Data System (ADS)

    Shu, Shi; Yu, Nu; Wang, Yueyan; Zhu, Yifang

    2015-12-01

    Air exchange rates (AERs) have a direct impact on traffic-related air pollutant (TRAP) levels inside vehicles. Taxi drivers are occupationally exposed to TRAP on a daily basis, yet there is limited measurement of AERs in taxi cabs. To fill this gap, AERs were quantified in 22 representative Los Angeles taxi cabs including 10 Prius, 5 Crown Victoria, 3 Camry, 3 Caravan, and 1 Uplander under realistic driving (RD) conditions. To further study the impacts of window position and ventilation settings on taxi AERs, additional tests were conducted on 14 taxis with windows closed (WC) and on the other 8 taxis with not only windows closed but also medium fan speed (WC-MFS) under outdoor air mode. Under RD conditions, the AERs in all 22 cabs had a mean of 63 h-1 with a median of 38 h-1. Similar AERs were observed under WC condition when compared to those measured under RD condition. Under WC-MFS condition, AERs were significantly increased in all taxi cabs, when compared with those measured under RD condition. A General Estimating Equation (GEE) model was developed and the modeling results showed that vehicle model was a significant factor in determining the AERs in taxi cabs under RD condition. Driving speed and car age were positively associated with AERs but not statistically significant. Overall, AERs measured in taxi cabs were much higher than typical AERs people usually encounter in indoor environments such as homes, offices, and even regular passenger vehicles.

  8. Evaluation of Burning Test Rate Method for Flammable Solids to Increase air-Cargo Safety.

    PubMed

    Lukežič, Marjan; Marinšek, Marjan; Faganeli, Jadran

    2010-03-01

    This paper deals with a standard classification procedure for readily combustible solids and their assignment to the relevant packing groups according to international air-cargo legislation and regulations. The current International Air Transport Association and United Nations Orange Book regulations were used on chemically similar substances: hexamethylenetetramine and Dancook ignition briquettes, which are both assigned into the same Packing Group III. To critically evaluate the degree of hazard both chemicals present, a standard burning test rate as well as thermogravimetry, differential scanning calorimetry and evolved gas analysis measurements were performed. It was shown that relatively small changes in the chemical composition of the material may have essential influence on the package group determination. Taking into account all the facts collected in the experimental work, it was concluded that ignition briquettes will undergo spontaneous combustion if exposed to elevated temperatures and, from this point of view, represent higher risk than hexamethylenetetramine during air transportation. Therefore, ignition briquettes should be classified into Packing Group II. PMID:24061664

  9. Effects of Temperature, Humidity and Air Flow on Fungal Growth Rate on Loaded Ventilation Filters.

    PubMed

    Tang, W; Kuehn, T H; Simcik, Matt F

    2015-01-01

    This study compares the fungal growth ratio on loaded ventilation filters under various temperature, relative humidity (RH), and air flow conditions in a controlled laboratory setting. A new full-size commercial building ventilation filter was loaded with malt extract nutrients and conidia of Cladosporium sphaerospermum in an ASHRAE Standard 52.2 filter test facility. Small sections cut from this filter were incubated under the following conditions: constant room temperature and a high RH of 97%; sinusoidal temperature (with an amplitude of 10°C, an average of 23°C, and a period of 24 hr) and a mean RH of 97%; room temperature and step changes between 97% and 75% RH, 97% and 43% RH, and 97% and 11% RH every 12 hr. The biomass on the filter sections was measured using both an elution-culture method and by ergosterol assay immediately after loading and every 2 days up to 10 days after loading. Fungal growth was detected earlier using ergosterol content than with the elution-culture method. A student's t-test indicated that Cladosporium sphaerospermum grew better at the constant room temperature condition than at the sinusoidal temperature condition. By part-time exposure to dry environments, the fungal growth was reduced (75% and 43% RH) or even inhibited (11% RH). Additional loaded filters were installed in the wind tunnel at room temperature and an RH greater than 95% under one of two air flow test conditions: continuous air flow or air flow only 9 hr/day with a flow rate of 0.7 m(3)/s (filter media velocity 0.15 m/s). Swab tests and a tease mount method were used to detect fungal growth on the filters at day 0, 5, and 10. Fungal growth was detected for both test conditions, which indicates that when temperature and relative humidity are optimum, controlling the air flow alone cannot prevent fungal growth. In real applications where nutrients are less sufficient than in this laboratory study, fungal growth rate may be reduced under the same operating conditions

  10. Field observations of turbulent dissipation rate profiles immediately below the air-water interface

    NASA Astrophysics Data System (ADS)

    Wang, Binbin; Liao, Qian

    2016-06-01

    Near surface profiles of turbulence immediately below the air-water interface were measured with a free-floating Particle Image Velocimetry (PIV) system on Lake Michigan. The surface-following configuration allowed the system to measure the statistics of the aqueous-side turbulence in the topmost layer immediately below the water surface (z≈0˜15 cm, z points downward with 0 at the interface). Profiles of turbulent dissipation rate (ɛ) were investigated under a variety of wind and wave conditions. Various methods were applied to estimate the dissipation rate. Results suggest that these methods yield consistent dissipation rate profiles with reasonable scattering. In general, the dissipation rate decreases from the water surface following a power law relation in the top layer, ɛ˜z-0.7, i.e., the slope of the decrease was lower than that predicted by the wall turbulence theory, and the dissipation was considerably higher in the top layer for cases with higher wave ages. The measured dissipation rate profiles collapse when they were normalized with the wave speed, wave height, water-side friction velocity, and the wave age. This scaling suggests that the enhanced turbulence may be attributed to the additional source of turbulent kinetic energy (TKE) at the "skin layer" (likely due to micro-breaking), and its downward transport in the water column.

  11. Temperature lapse rates at restricted thermodynamic equilibrium. Part II: Saturated air and further discussions

    NASA Astrophysics Data System (ADS)

    Björnbom, Pehr

    2016-03-01

    In the first part of this work equilibrium temperature profiles in fluid columns with ideal gas or ideal liquid were obtained by numerically minimizing the column energy at constant entropy, equivalent to maximizing column entropy at constant energy. A minimum in internal plus potential energy for an isothermal temperature profile was obtained in line with Gibbs' classical equilibrium criterion. However, a minimum in internal energy alone for adiabatic temperature profiles was also obtained. This led to a hypothesis that the adiabatic lapse rate corresponds to a restricted equilibrium state, a type of state in fact discussed already by Gibbs. In this paper similar numerical results for a fluid column with saturated air suggest that also the saturated adiabatic lapse rate corresponds to a restricted equilibrium state. The proposed hypothesis is further discussed and amended based on the previous and the present numerical results and a theoretical analysis based on Gibbs' equilibrium theory.

  12. Effect of surfactants on the rate of growth of an air bubble by rectified diffusion.

    PubMed

    Lee, Judy; Kentish, Sandra; Ashokkumar, Muthupandian

    2005-08-01

    The rectified diffusion growth of a single air bubble levitated in an acoustic field (frequency = 22.35 kHz) in water and in aqueous solutions containing surfactants (sodium dodecyl sulfate and sodium dodecylbenzene sulfonate) was investigated. As reported by Crum (J. Acoust. Soc. Am. 1980, 68, 203), the presence of surfactants at the bubble/liquid interface enhanced the growth rate of the bubble by rectified diffusion. It is suggested in this paper that in addition to the effect of surfactants on the surface tension and interfacial resistance to mass transfer, the effect of surface rheological properties may also contribute to the cause of the enhancement observed in the bubble growth rate. PMID:16852840

  13. Effects of air oxidation on the dissolution rate of LWR spent fuel

    SciTech Connect

    Gray, W.J.; Thomas, L.E.; Einziger, R.E.

    1993-12-31

    Dissolution rates for air-oxidized spent fuel were measured in flowthrough tests where U concentrations were kept well below the solubility limit. Results from two types of specimens, separated grains and coarse particles, both in oxidized (U{sub 4}O{sub 9+x}) and unoxidized (UO{sub 2}) conditions indicated only minor effects of oxidation on the surface-area-normalized rates. Similar results were obtained for unirradiated specimens in three different oxidation states (UO{sub 2}, U{sub 3}O{sub 7}, and U{sub 3}O{sub 8}). These observations have important practical implications for disposal of spent fuel in a geologic repository as well as implications regarding the oxidative dissolution mechanism of UO{sub 2} fuel.

  14. Measurement of Ozone Emission and Particle Removal Rates from Portable Air Purifiers

    ERIC Educational Resources Information Center

    Mang, Stephen A.; Walser, Maggie L.; Nizkorodov, Sergey A.; Laux, John M.

    2009-01-01

    Portable air purifiers are popular consumer items, especially in areas with poor air quality. Unfortunately, most users of these air purifiers have minimal understanding of the factors affecting their efficiency in typical indoor settings. Emission of the air pollutant ozone (O[subscript 3]) by certain air purifiers is of particular concern. In an…

  15. Biofiltration of air contaminated by styrene: Effect of nitrogen supply, gas flow rate, and inlet concentration

    SciTech Connect

    Jorio, H.; Bibeau, L.; Heitz, M.

    2000-05-01

    The biofiltration process is a promising technology for the treatment of dilute styrene emissions in air. The efficiency of this process is however strongly dependent upon various operational parameters such as the filter bed characteristics, nutrient supplies, input contaminant concentrations, and gas flow rates. The biofiltration of air containing styrene vapors was therefore investigated, employing a novel biomass filter material, in two identical but separate laboratory scale biofiltration units (units 1 and 2), both biofilters being initially inoculated with a microbial consortium. Each biofilter was irrigated with a nutrient solution supplying nitrogen in one of two forms; i.e., mainly as ammonia for unit 1 and exclusively as nitrate for unit 2. The experimental results have revealed that greater styrene elimination rates are achieved in the biofilter supplied with ammonia as the major nitrogen source in comparison to the lesser elimination performance obtained with the nitrate provided biofilter. However, in achieving the high styrene removal rates in the ammonia supplied biofilter, the excess of biomass accumulates on the filtering pellets and causes progressive clogging of the filter media. Furthermore, the effectiveness of nitrate supply as the sole nitrogen nutrient form, on reducing or controlling the biomass accumulation in the filter media in comparison to ammonia, could not be satisfactorily demonstrated because the two biofilters operated with very different styrene elimination capacities. The monitoring of the carbon dioxide concentration profile through both biofilters revealed that the ratio of carbon dioxide produced to the styrene removed was approximately 3/1, which confirms the complete biodegradation of removed styrene, given that some of the organic carbon consumed is also used for the microbial growth. The effects of the most important design parameters, namely styrene input concentrations and gas flow rates, were investigated for each

  16. TWO NEW DUCT LEAKAGE TESTS

    SciTech Connect

    ANDREWS,J.W.

    1998-12-01

    Two variations on the tests for duct leakage currently embodied in ASHRAE Standard 152P (Method of Test for Determining the Design and Seasonal Efficiencies of Residential Thermal Distribution Systems) are presented. Procedures are derived for calculating supply and return duct leakage to/from outside using these new variations. Results of these tests are compared with the original ones in Standard 152P on the basis of data collected in three New York State homes.

  17. Two New Duct Leakage Tests

    SciTech Connect

    Andrews, J.W.

    1998-12-01

    Two variations on the tests for duct leakage currently embodied in ASHRAE Standard 152P (Method of Test for Determining the Design and Seasonal Efficiencies of Residential Thermal Distribution Systems) are presented. Procedures are derived for calculating supply and return duct leakage to/from outside using these new variations. Results of these tests are compared with the original ones in Standard 152P on the basis of data collected in three New York State homes.

  18. Safety management of nuclear medicine personnel with visualisation of air dose rate.

    PubMed

    Kawase, S; Ohno, K; Nakamoto, Y; Miyatake, H

    2015-07-01

    Many people are anxious about radiation exposure for the reason that radiation cannot be seen. With the aim of devising a way for medical personnel to perform their medical duties without worry about radiation exposure, we attempted safety management using a system that displays the air dose of radiation in real time. Measurements were made in a lung ventilation scintigraphy examination room with the use of Xe-133. An SCI-type RI detector from Hamamatsu Photonics, which displays the air dose rate in real time, was used for the measurements. These radiation measurements were continued from the start to finish of the examination. The measurements were made in two locations, on the patient inhalation tube side and on the opposite side. Measurements were made on the patient tube side in 24 tests and on the opposite side in 12 tests. The maximum air dose rate was 3.7 ± 2.1 μSv/h on the patient tube side and 1.1 ± 0.5 μSv/h on the opposite side. Thus, the level on the opposite side was about 1/5 that of the tube side. To accurately perform lung ventilation scintigraphy, a medical worker needs to observe the patient's breathing status up close. Because of this, some medical workers are worried about radiation exposure during tests. The simplest way to reduce exposure would be to maintain a distance from the examination tube that is the source of radiation. The measurements in this study were made to encourage medical workers' recognition of this fact. Displaying specific numbers not only serves as basic data for managing staff operations, but is also thought to reassure workers through visualization. PMID:25889608

  19. Temperature-Induced Leakage from Chilling-Sensitive and Chilling-Resistant Plants 12

    PubMed Central

    Paull, Robert E.

    1981-01-01

    Leakage rates were determined from leaf cells loaded with rubidium and [3H]leucine. There was a differential response between leucine and rubidium leakage depending upon the species used. The rate of leucine leakage shows a small decline below 5 C for two altitudinal variants of Lycopersicon hirsutum Humb. and Bonpl., whereas Lycopersicon esculentum L. showed a marked increase below 5 C. Rubidium showed a marked increase in leakage rate below 10 C with the altitudinal variants, with only a slight increase for the L. esculentum species. A rough relationship existed between rubidium leakage rate at 1 C and the altitude of origin of the L. hirsutum race, the low altitudinal forms having higher leakage rates than the higher altitudinal variants. The L. esculentum lines show a rubidium leakage response similar to that of the high altitude L. hirsutum variants. Higher leakage rates were obtained if the calcium concentration in the medium was less than 1 millimolar and upon addition of metabolic poisons and detergents. The results are consistent with the view that chilling injury causes changes in the membrane and that cell leakage is an early symptom of this change in some species. Some chilling-sensitive species have increased leakage within 1 hour of exposure to chilling temperature. PMID:16661859

  20. Temperature and strain rate effects in high strength high conductivity copper alloys tested in air

    SciTech Connect

    Edwards, D.J.

    1998-03-01

    The tensile properties of the three candidate alloys GlidCop{trademark} Al25, CuCrZr, and CuNiBe are known to be sensitive to the testing conditions such as strain rate and test temperature. This study was conducted on GlidCop Al25 (2 conditions) and Hycon 3HP (3 conditions) to ascertain the effect of test temperature and strain rate when tested in open air. The results show that the yield strength and elongation of the GlidCop Al25 alloys exhibit a strain rate dependence that increases with temperature. Both the GlidCop and the Hycon 3 HP exhibited an increase in strength as the strain rate increased, but the GlidCop alloys proved to be the most strain rate sensitive. The GlidCop failed in a ductile manner irrespective of the test conditions, however, their strength and uniform elongation decreased with increasing test temperature and the uniform elongation also decreased dramatically at the lower strain rates. The Hycon 3 HP alloys proved to be extremely sensitive to test temperature, rapidly losing their strength and ductility when the temperature increased above 250 C. As the test temperature increased and the strain rate decreased the fracture mode shifted from a ductile transgranular failure to a ductile intergranular failure with very localized ductility. This latter observation is based on the presence of dimples on the grain facets, indicating that some ductile deformation occurred near the grain boundaries. The material failed without any reduction in area at 450 C and 3.9 {times} 10{sup {minus}4} s{sup {minus}1}, and in several cases failed prematurely.

  1. Radiative and turbulent heating rates in the clear-air boundary layer

    NASA Astrophysics Data System (ADS)

    Savijärvi, Hannu

    2006-01-01

    The diurnal evolution of a clear-sky midlatitude summertime boundary layer (BL) was studied using a column model over smooth and homogeneous land, subject to weak, moderate, and strong winds. The high-resolution BL model (lowest point at 30 cm) was equipped with an adequate turbulence scheme and a narrow-band long-wave (LW) radiation scheme, the latter validated using data from the International Comparison of Radiation Codes in Climate Models (ICRCCM).In off-line ICRCCM experiments, ground emissivity ɛ < 1 led to extra LW cooling of air near the surface compared to ɛ = 1. However, much stronger LW cooling at heights of 1 3 m, and warming below 1 m, was obtained by setting the ground colder than air at screen height, a typical condition during clear nights. Conversely, a warm surface anomaly typical of sunny days leads to strong LW warming at 1 3 m, with LW cooling just above the ground. These ground temperature anomalies dominated the LW heating/cooling patterns at heights of up to 3 4 m, perhaps explaining controversies in the observed LW flux divergences close to the ground.Interactive model results indicate that the middle part of a windy clear-air nocturnal BL (NBL) is dominated by turbulent cooling, while the upper and lower NBL is dominated by LW cooling. Below about 1 m, a fourth layer is formed with LW warming and turbulent cooling, in agreement with the off-line experiments. When the surface winds fall below about 1 1.5 m s -1 LW cooling dominates in the whole NBL, except very near the surface. In these light wind conditions the Monin Obukhov theory should be revised to include radiative effects.In clear-air daytime conditions strong convective BL heating dominates over weak LW cooling except at 1 3 m heights where the cooler air absorbs the thermal emission of the hot ground. The subsequent LW warming of the superadiabatic surface layer appears to be strong enough to induce local turbulent cooling (despite the hot surface) in an 'hour glass' pattern

  2. 49 CFR 178.346-5 - Pressure and leakage tests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... CFR 63.425(e). To satisfy the leakage test requirements of this paragraph, the test specified in 40 CFR 63.425(e)(1) must be conducted using air. The hydrostatic test alternative permitted under Appendix A to 40 CFR Part 60 (“Method 27—Determination of Vapor Tightness of Gasoline Delivery Tank...

  3. The effects of outdoor air supply rate in an office on perceived air quality, sick building syndrome (SBS) symptoms and productivity.

    PubMed

    Wargocki, P; Wyon, D P; Sundell, J; Clausen, G; Fanger, P O

    2000-12-01

    Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in a normally furnished office space (108 m3) ventilated with an outdoor airflow of 3, 10 or 30 L/s per person, corresponding to an air change rate of 0.6, 2 or 6 h-1. The temperature of 22 degrees C, the relative humidity of 40% and all other environmental parameters remained unchanged. Five groups of six female subjects were each exposed to the three ventilation rates, one group and one ventilation rate at a time. Each exposure lasted 4.6 h and took place in the afternoon. Subjects were unaware of the intervention and remained thermally neutral by adjusting their clothing. They assessed perceived air quality and SBS symptoms at intervals, and performed simulated normal office work. Increasing ventilation decreased the percentage of subjects dissatisfied with the air quality (P < 0.002) and the intensity of odour (P < 0.02), and increased the perceived freshness of air (P < 0.05). It also decreased the sensation of dryness of mouth and throat (P < 0.0006), eased difficulty in thinking clearly (P < 0.001) and made subjects feel generally better (P < 0.0001). The performance of four simulated office tasks improved monotonically with increasing ventilation rates, and the effect reached formal significance in the case of text-typing (P < 0.03). For each two-fold increase in ventilation rate, performance improved on average by 1.7%. This study shows the benefits for health, comfort and productivity of ventilation at rates well above the minimum levels prescribed in existing standards and guidelines. It confirms the results of a previous study in the same office when the indoor air quality was improved by decreasing the pollution load while the ventilation remained unchanged. PMID:11089327

  4. The effect of inhalation resistance on facepiece leakage.

    PubMed

    Nelson, T J; Colton, C E

    2000-01-01

    Air purifying respirators use filters to remove particulate air contaminants. Resistance to airflow generally increases as the filter loads and a "filter cake" is formed. It has been recommended by ANSI and the Occupational Safety and Health Administration that filters should be replaced when the wearer notices they are hard to breathe through. Repeated faceseal leak rate measurements were made during respiratory wear over a range of simulated breathing resistances from 5.6 to 19.6 mm (0.22 to 0.77 inches) of water. The measured faceseal leak rates increased as the breathing resistance increased and varied depending on the initial leak rate at the 5.6 mm pressure. The increase in faceseal leak rate from 5.6 to 19.6 mm breathing resistance was as high as a factor of 4. Theoretically, a person with an initial respirator penetration of 2.5% could have that value increase to 10% as filter loading increased breathing resistance by 14 mm. Some research has shown that breathing resistances between 60 and 140 mm of water would be "noticeable but well tolerated." It is not known if workers would be able to detect an increase in breathing resistance that would lead to a significant increase in faceseal leakage. These data suggest a need to establish a replacement schedule for all filters used in the workplace. How often a filter should be replaced is difficult to determine. Breathing resistance would vary depending on the individual filter and aerosol loading characteristics, the concentration of the aerosol in the workplace, and breathing rates. PMID:10772622

  5. Hydrocarbon Observations and Ozone Production Rates in Western Houston During the Texas 2000 Air Quality Study

    SciTech Connect

    Berkowitz, Carl M.; Spicer, Chet W.; Doskey, Paul V.

    2005-06-01

    Measurements of total non-methane hydrocarbon in whole air canisters collected from the top of a skyscraper on the western edge of Houston, Texas are summarized with an emphasis on samples collected during the passage of plumes of O{sub 3} and the associated rapid increase in the mixing ratio of this species. The back-trajectories associated with these events showed a pronounced deceleration of air parcels over central and western Houston and were not necessarily associated with direct passage over the petrochemical plants located in the heavily industrialized eastern part of Houston. As a result of the time these air parcels spent over the central and western parts of Houston, their VOC mix and associated chemical production rates were expected to differ from similar observations made over eastern Houston from aircraft sampling at low altitudes. Although periods of high O{sub 3} in the western part of the city were closely associated with light alkenes, these same observations show isoprene to make a significant contribution to the total VOC reactivity in the early afternoon (the start of peak photochemical activity) in contrast to observations made east of our sampling site that found the reactivity to be dominated by anthropogenic species. By initializing a 0-dimensional chemical kinetic model with observations made at the Williams Tower, we find that the ozone production efficiency scaled linearly to the ratio of total hydrocarbons and NO{sub x}, with an average OPE of 7.2, ranging from 2.3 to 16.9; these values are smaller than those reported in eastern Houston, suggesting a strong gradient in photochemical productivity across the city.

  6. Indoor Air Pollution, Nighttime Heart Rate Variability and Coffee Consumption among Convenient Store Workers

    PubMed Central

    Chuang, Kai-Jen; Chuang, Hsiao-Chi; Lin, Lian-Yu

    2013-01-01

    Background The association between ambient air pollution and heart rate variability (HRV) has been well-documented. Little is known about the association of HRV at night with indoor air pollution and coffee consumption. The aim of this study was to investigate the association of HRV indices with indoor air pollution, working time and coffee consumption. Methods We recruited 60 young healthy convenient store workers to monitor indoor PM2.5 (particulate matter with an aerodynamic diameter ≤ 2.5 µm) exposures, coffee consumption (yes vs. no) and HRV indices during daytime (0700–1500 hours) and nighttime (2300-0700 hours). We used linear mixed effects models to assess the associations of HRV indices with indoor PM2.5 exposures and coffee consumption. Results We observed the inverse association between indoor PM2.5 exposures and HRV indices, with a decrease in all HRV indices with increased indoor PM2.5 exposures. However, the decrease was most pronounced during nighttime, where a 1 interquartile range (IQR) increase in indoor PM2.5 at 4-hr time-weighted moving average was associated with a change of −4.78% 5-min standard deviation (SD) of normal-to-normal intervals for 5-min segment (SDNN) and −3.23% 5-min square root of the mean squared differences of successive intervals for 5-min segment (r-MSSD). Effects of indoor PM2.5 were lowest for participants with coffee consumption during daytime. Conclusions Indoor PM2.5 exposures were associated with decreased 5-min SDNN and 5-min r-MSSD, especially during nighttime. The effect of indoor PM2.5 on HRV indices may be modified by coffee consumption in young healthy convenient store workers. PMID:24312680

  7. Some preliminary results of brush seal/rotor interference effects on leakage at zero and low rpm using a tapered-plug rotor

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Proctor, M. P.; Schlumberger, J. A.; Braun, M. J.; Mullen, R. L.

    1991-01-01

    Some preliminary brush seal leakage results for ambient-temperature air are presented. Data for four nominal brush-rotor radial clearances of -0.09, -0.048, -0.008, and 0.035 mm were taken by using a tapered plug rotor at 0 and 400 rpm with rotor runout of 0.127 mm peak to peak. The brush seal nominal bore diameter was 38 mm with 0.05-mm bristles at 200 bristles/mm of circumference and a 0.61-mm fence height. Leakages were greater than predicted, but agreement was reasonable. Leakage rates were not significantly altered by hysteresis or inlet flow variations. Visualization studies showed that the bristles followed the 400-rpm excitation, and loading studies indicated that bristles slid relative to one another.

  8. Some preliminary results of brush seal/rotor interference effects on leakage at zero and low RPM using a tapered-plug rotor

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Proctor, M. P.; Schlumberger, J. A.; Braun, M. J.; Mullen, R. L.

    1991-01-01

    Some preliminary brush seal leakage results for ambient temperature air are presented. Data for four nominal brush rotor radial clearances of -0.09, -0.048, -0.008, and 0.035 mm were taken by using a tapered plug rotor at 0 and 400 rpm with rotor runout of 0.127 mm peak to peak. The brush seal nominal bore diameter was 38 mm with 0.05 mm bristles at 200 bristles/mm of circumference and a 0.61 mm fence height. Leakages were greater than predicted, but agreement was reasonable. Leakage rates were not significantly altered by hysteresis or inlet flow variations. Visualization studies showed that the bristles followed the 400 rpm excitation, and loading studies indicated that bristles slid relative to one another.

  9. Analysis of turbulent free jet hydrogen-air diffusion flames with finite chemical reaction rates

    NASA Technical Reports Server (NTRS)

    Sislian, J. P.

    1978-01-01

    The nonequilibrium flow field resulting from the turbulent mixing and combustion of a supersonic axisymmetric hydrogen jet in a supersonic parallel coflowing air stream is analyzed. Effective turbulent transport properties are determined using the (K-epsilon) model. The finite-rate chemistry model considers eight reactions between six chemical species, H, O, H2O, OH, O2, and H2. The governing set of nonlinear partial differential equations is solved by an implicit finite-difference procedure. Radial distributions are obtained at two downstream locations of variables such as turbulent kinetic energy, turbulent dissipation rate, turbulent scale length, and viscosity. The results show that these variables attain peak values at the axis of symmetry. Computed distributions of velocity, temperature, and mass fraction are also given. A direct analytical approach to account for the effect of species concentration fluctuations on the mean production rate of species (the phenomenon of unmixedness) is also presented. However, the use of the method does not seem justified in view of the excessive computer time required to solve the resulting system of equations.

  10. An experimental investigation on the effects of surface gravity waves on the water evaporation rate in different air flow regimes

    NASA Astrophysics Data System (ADS)

    Jodat, Amin; Moghiman, Mohammad; Shirkhani, Golshad

    2013-12-01

    Estimating rate of evaporation from undisturbed water surfaces to moving and quiet air has been the topic a vast number of research activities. The obvious presence of various shapes of gravity waves on the water body surfaces was the motivation of this experimental investigation. In this investigation experimental measurements have been done to quantify evaporation rate from wavy water surfaces in free, mixed and forced convection regimes. The effects of a wide range of surface gravity waves from low steepness, round shaped crest with slow celerity, to steep and very slight spilling crest waves, on the water evaporation rate have been investigated. A wide range of was achieved by applying different air flow velocities on a large heated wave flume equipped with a wind tunnel. Results reveal that wave motion on the water surface increase the rate of evaporation for all air flow regimes. For free convection, due to the effect of wave motion for pumping rotational airflows at the wave troughs and the dominant effect of natural convection for the air flow advection, the maximum evaporation increment percentage from wavy water surface is about 70 %. For mixed and forced convection, water evaporation rate increment is more sensitive to the air flow velocity for the appearance of very slight spilling on the steep wave crests and the leeward air flow structures.

  11. Effects of oblique air flow on burning rates of square ethanol pool fires.

    PubMed

    Tao, Changfa; He, Yaping; Li, Yuan; Wang, Xishi

    2013-09-15

    The effects of downward airflow on the burning rate and/or burning intensity of square alcohol pool fires for different airflow speeds and directions have been studied experimentally in an inclined wind tunnel. An interesting flame-wrapping phenomenon, caused by impingement of air flow, was observed. The mass burning intensity was found to increase with the airflow speed and the impinging angle. The fuel pan rim temperatures were also measured to study the effect of wind direction and speed on heat transfer from the flame to the fuel source. A model based on heat transfer analysis was developed to correlate the burning intensity with the pan rim characteristic temperature. A good correlation was established between the model results and the experimental results. PMID:23811377

  12. Cement Leakage into Adjacent Vertebral Body Following Percutaneous Vertebroplasty

    PubMed Central

    Park, Jae Hoo; Kim, Hyeun Sung

    2016-01-01

    Percutaneous vertebroplasty (PV) is a minimally invasive procedure for osteoporotic vertebral compression fractures that fail to respond to conventional conservative treatment. It significantly improves intolerable back pain within hours, and has a low complication rate. Although rare, PV is not free of complications, most of which are directly related to cement leakage. Because of its association with new adjacent fracture, the importance of cement leakage into the adjacent disc space is paramount. Here, we report an interesting case of cement leakage into the adjacent upper vertebral body as well as disc space following PV. To the best of our knowledge, there has been no report of cement leakage into the adjacent vertebral body following PV. This rare case is presented along with a review of the literature. PMID:27437018

  13. Wall surface leakage effects on MHD power generator performance

    SciTech Connect

    Pian, C.C.P.; Schmitt, E.W.

    1994-12-31

    Internal surface leakage effects on the MHD generator performance were studied using a combined experimental and analytical approach. A method to determine the wall resistances and slag layer conductivities from seed shut-off test data is introduced. These measured resistance values are then utilized in generator performance analyses. Calculated results were compared with measured data from MHD generator tests to verify the modeling approach. Finally, these calculated results were used to investigate the distribution of internal leakage currents as a function of generator size, generator operating conditions, and iron oxide injection rates. An advantage of this analysis methodology is the ability to differentiate between wall leakage and apparent leakage effects in the measured test data.

  14. Leakage currents in SOI MOSFETS

    SciTech Connect

    Annamala, N.K.; Biwer, M.C.

    1988-12-01

    Total dose response of both NMOS and PMOS FETs fabricated on SOI substrates was studied. Two types of back-channel leakage currents were identified. A back-channel leakage due to MOSFET action uses the substrate bias as the gate bias. The other component is due to soft reverse characteristics of the body-drain junction. The back-channel leakage due to MOSFET action varies with the substrate bias and hence varies with irradiation due to threshold voltage shift. The soft reverse characteristics are a function of drain-body voltage and hence vary with substrate bias and irradiation. I-V characteristics and subthreshold currents of both front and back channels as a function of total dose were obtained.

  15. Effects of metabolic rate on thermal responses at different air velocities in -10 degrees C.

    PubMed

    Mäkinen, T T; Gavhed, D; Holmér, I; Rintamäki, H

    2001-04-01

    The effects of exercise intensity on thermoregulatory responses in cold (-10 degrees C) in a 0.2 (still air, NoWi), 1.0 (Wi1), and 5.0 (Wi5) m x s(-1) wind were studied. Eight young and healthy men, preconditioned in thermoneutral (+20 degrees C) environment for 60 min, walked for 60 min on the treadmill at 2.8 km/h with different combinations of wind and exercise intensity. Exercise level was adjusted by changing the inclination of the treadmill between 0 degrees (lower exercise intensity, metabolic rate 124 W x m(-2), LE) and 6 degrees (higher exercise intensity, metabolic rate 195 W x m(-2), HE). Due to exercise increased heat production and circulatory adjustments, the rectal temperature (T(re)), mean skin temperature (Tsk) and mean body temperature (Tb) were significantly higher at the end of HE in comparison to LE in NoWi and Wi1, and T(re) and Tb also in Wi5. Tsk and Tb were significantly decreased by 5.0 m x s(-1) wind in comparison to NoWi and Wi1. The higher exercise intensity was intense enough to diminish peripheral vasoconstriction and consequently the finger skin temperature was significantly higher at the end of HE in comparison to LE in NoWi and Wi1. Mean heat flux from the skin was unaffected by the exercise intensity. At LE oxygen consumption (VO2) was significantly higher in Wi5 than NoWi and Wi1. Heart rate was unaffected by the wind speed. The results suggest that, with studied exercise intensities, produced without changes in walking speed, the metabolic rate is not so important that it should be taken into consideration in the calculation of wind chill index. PMID:11282319

  16. The association of particulate air metal concentrations with heart rate variability.

    PubMed Central

    Magari, Shannon R; Schwartz, Joel; Williams, Paige L; Hauser, Russ; Smith, Thomas J; Christiani, David C

    2002-01-01

    Numerous studies show an association between particulate air pollution and adverse health effects. Particulate matter is a complex mixture of elemental carbon, ammonium, sulfates, nitrates, organic components, and metals. The mechanisms of action of particulate matter less than or equal to 2.5 micro m in mean aerodynamic diameter (PM(2.5)), as well as the constituents responsible for the observed cardiopulmonary health effects, have not been identified. In this study we focused on the association between the metallic component of PM(2.5) and cardiac autonomic function based on standard heart rate variability (HRV) measures in an epidemiologic study of boilermakers. Thirty-nine male boilermakers were monitored throughout a work shift. Each subject wore an ambulatory electrocardiogram (Holter) monitor and a personal monitor to measure PM(2.5). We used mixed-effects models to regress heart rate and SDNN index (standard deviation of the normal-to-normal) on PM(2.5) and six metals (vanadium, nickel, chromium, lead, copper, and manganese). There were statistically significant mean increases in the SDNN index of 11.30 msec and 3.98 msec for every 1 micro g/m(3) increase in the lead and vanadium concentrations, respectively, after adjusting for mean heart rate, age, and smoking status. Small changes in mean heart rate were seen with all exposure metrics. The results of this study suggest an association between exposure to airborne metals and significant alterations in cardiac autonomic function. These results extend our understanding of the adverse health effects of the metals component of ambient PM(2.5). PMID:12204821

  17. Childhood cancer incidence rates and hazardous air pollutants in California: an exploratory analysis.

    PubMed Central

    Reynolds, Peggy; Von Behren, Julie; Gunier, Robert B; Goldberg, Debbie E; Hertz, Andrew; Smith, Daniel F

    2003-01-01

    Hazardous air pollutants (HAPs) are compounds shown to cause cancer or other adverse health effects. We analyzed population-based childhood cancer incidence rates in California (USA) from 1988 to 1994, by HAP exposure scores, for all California census tracts. For each census tract, we calculated exposure scores by combining cancer potency factors with outdoor HAP concentrations modeled by the U.S. Environmental Protection Agency. We evaluated the relationship between childhood cancer rates and exposure scores for 25 potentially carcinogenic HAPs emitted from mobile, area, and point sources and from all sources combined. Our study period saw 7,143 newly diagnosed cancer cases in California; of these, 6,989 (97.8%) could be assigned to census tracts and included in our analysis. Using Poisson regression, we estimated rate ratios (RRs) adjusted for age, race/ethnicity, and sex. We found little evidence for elevated cancer RRs for all sites or for gliomas among children living in high-ranking combined-source exposure areas. We found elevated RRs and a significant trend with increasing exposure level for childhood leukemia in tracts ranked highest for exposure to the combined group of 25 HAPs (RR = 1.21; 95% confidence interval, 1.03, 1.42) and in tracts ranked highest for point-source HAP exposure (RR = 1.32; 95% confidence interval, 1.11, 1.57). Our findings suggest an association between increased childhood leukemia rates and high HAP exposure, but studies involving more comprehensive exposure assessment and individual-level exposure data will be important for elucidating this relationship. PMID:12676632

  18. Chemical characterization of indoor air of homes from communes in Xuan Wei, China, with high lung cancer mortality rates

    EPA Science Inventory

    In a rural county, Xuan Wei, China, the lung cancer mortality rate is among China's highest, especially in women. This mortality rate is more associated with indoor air burning of smoky coal, as opposed to smokeless coal or wood, for cooking and heating under unvented conditions....

  19. Influence of travel speed on spray deposition uniformity from an air-assisted variable-rate sprayer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A newly developed LiDAR-guided air-assisted variable-rate sprayer for nursery and orchard applications was tested at various travel speeds to compare its spray deposition and coverage uniformity with constant-rate applications. Spray samplers, including nylon screens and water-sensitive papers (WSP)...

  20. Experimental and numerical investigations on the leakage flow characteristics of labyrinth seals

    NASA Astrophysics Data System (ADS)

    Li, Jun; Wen, Kesong; Wang, Shizhu; Jiang, Shengke; Kong, Xianglin

    2013-07-01

    Experimental measurements and numerical simulations were conducted to analyze the leakage flow characteristics of the labyrinth seals in this work. Rotating seal test rig was used to measure the leakage flow rate of the labyrinth seals. The detailed leakage flow fields of the labyrinth seals at the experimental measurement conditions were investigated by solving three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations and k- turbulent model. Effects of the pressure ratio and rotational speed on the leakage flow characteristics of labyrinth seals were studied using the experimental and numerical approaches. The obtained results show that the rotational speed has little influence on the leakage flow rate of the labyrinth seal. The leakage flow rate of the labyrinth seal linearly increase with increasing the pressure ratio at the same sealing clearance and rotational speed. The flow pattern of the labyrinth seal was also illustrated.

  1. Uneven futures of human lifespans: reckonings from Gompertz mortality rates, climate change, and air pollution.

    PubMed

    Finch, Caleb E; Beltrán-Sánchez, Hiram; Crimmins, Eileen M

    2014-01-01

    The past 200 years have enabled remarkable increases in human lifespans through improvements in the living environment that have nearly eliminated infections as a cause of death through improved hygiene, public health, medicine, and nutrition. We argue that the limit to lifespan may be approaching. Since 1997, no one has exceeded Jeanne Calment's record of 122.5 years, despite an exponential increase of centenarians. Moreover, the background mortality may be approaching a lower limit. We calculate from Gompertz coefficients that further increases in longevity to approach a life expectancy of 100 years in 21st century cohorts would require 50% slower mortality rate accelerations, which would be a fundamental change in the rate of human aging. Looking into the 21st century, we see further challenges to health and longevity from the continued burning of fossil fuels that contribute to air pollution as well as global warming. Besides increased heat waves to which elderly are vulnerable, global warming is anticipated to increase ozone levels and facilitate the spread of pathogens. We anticipate continuing socioeconomic disparities in life expectancy. PMID:24401556

  2. Analysis of turbulent free-jet hydrogen-air diffusion flames with finite chemical reaction rates

    NASA Technical Reports Server (NTRS)

    Sislian, J. P.; Glass, I. I.; Evans, J. S.

    1979-01-01

    A numerical analysis is presented of the nonequilibrium flow field resulting from the turbulent mixing and combustion of an axisymmetric hydrogen jet in a supersonic parallel ambient air stream. The effective turbulent transport properties are determined by means of a two-equation model of turbulence. The finite-rate chemistry model considers eight elementary reactions among six chemical species: H, O, H2O, OH, O2 and H2. The governing set of nonlinear partial differential equations was solved by using an implicit finite-difference procedure. Radial distributions were obtained at two downstream locations for some important variables affecting the flow development, such as the turbulent kinetic energy and its dissipation rate. The results show that these variables attain their peak values on the axis of symmetry. The computed distribution of velocity, temperature, and mass fractions of the chemical species gives a complete description of the flow field. The numerical predictions were compared with two sets of experimental data. Good qualitative agreement was obtained.

  3. Uneven Futures of Human Lifespans: Reckonings from Gompertz Mortality Rates, Climate Change, and Air Pollution

    PubMed Central

    Finch, Caleb E; Beltrán-Sánchez, Hiram; Crimmins, Eileen M

    2014-01-01

    The past 200 years have enabled remarkable increases in human lifespans thru improvements of the living environment that have nearly eliminated infections as a cause of death through improved hygiene- public health, medicine, and nutrition. We argue that the limit to lifespan may be approaching. Since 1997, no one has exceeded Jean Calment's record of 122.5 years, despite an exponential increase of centenarians. Moreover, the background mortality may be approaching a lower limit. We calculate from Gompertz coefficients that further increases in longevity to approach a life expectancy of 100 years in 21st C cohorts would require 50% slower mortality rate accelerations, which would be a fundamental change in the rate of human aging. Looking into the 21st C, we see further challenges to health and longevity from the continued burning of fossil fuels that contribute to air pollution, as well as global warming. Besides increased heat waves to which elderly are vulnerable, global warming is anticipated to increase ozone levels and to favor the spread of pathogens. We anticipate continuing socio-economic disparities of life expectancy. PMID:24401556

  4. Model-based flow rate control for an orfice-type low-volume air sampler

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The standard method of measuring air suspended particulate matter concentration per volume of air consists of continuously drawing a defined volume of air across a filter over an extended period of time, then measuring the mass of the filtered particles and dividing it by the total volume sampled ov...

  5. THE CARBON DIOXIDE LEAKAGE FROM CHAMBERS MEASURED USING SULFUR HEXAFLUORIDE

    EPA Science Inventory

    In plant chamber studies, if Co2 leaking from a chamber is not quantified, it can lead to an overestimate of assimilation rates and an underestimate of respiration rates: consequently, it is critical that Co2 leakage be determined. Sulfur Hexafluoride (SF6) was introduced into t...

  6. The influence of surface sorption and air flow rate on phthalate emissions from vinyl flooring: Measurement and modeling

    NASA Astrophysics Data System (ADS)

    Liang, Yirui; Xu, Ying

    2015-02-01

    This study investigated the influences of surface sorption and air flow rate on the emission of phthalates from building materials. Controlled tests were conducted in specially designed stainless steel and wood chambers, and the steady-state concentration in the stainless steel chamber was about 2-3 times higher than that in the wood chamber for di(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP). The emission rate of phthalates increased in the wood chamber due to the diffusion mass flow through the chamber wall (i.e., surface absorption). The adsorption isotherm of phthalates on the stainless steel surface and the absorption parameters (i.e., diffusion and partition coefficients) of phthalates on the wood surface were determined experimentally, and the values were comparable to those in the literature. The equilibration time scale for phthalates absorbed to the sink reservoir in actual indoor environments was estimated and can be substantial (approximately 80 years), indicating that surface absorption may continuously drive phthalates from their indoor sources to various sinks and thus significantly increase the emission rate of phthalates. The gas-phase concentration of DEHP was measured in two stainless steel chambers operated at flow rates of 300 mL/min and 3000 mL/min, respectively, which were both adjusted to 1000 mL/min after steady state was reached. The gas-phase concentration of DEHP in the chamber was very sensitive to the chamber air flow rate, and higher air flow rates resulted in lower concentration levels. However, the increased emission rate compensated for the dilution in the gas phase and made the DEHP concentration not drop substantially with an increase in the air flow rate. Independently measured or calculated parameters were used to validate a semi-volatile organic compounds (SVOCs) emission model that included absorptive surfaces and for a range of air flow rates, with excellent agreement between the model predictions and the

  7. Expedient methods of respiratory protection. II. Leakage tests. Final report

    SciTech Connect

    Cooper, D.W.; Hinds, W.C.; Price, J.M.; Weker, R.; Yee, H.S.

    1983-07-01

    The following readily-available materials were tested on a manikin connected to a breathing simulator to determine the fraction of an approximately 2-..mu..m-diameter aerosol that would leak around the seal of the materials to the manikin's face: cotton/polyester shirt material, cotton handkerchief material, toweling (a wash cloth), a surgical mask (Johnson and Johnson Co., model HRI 8137), and a NIOSH-approved disposable face mask (3M, model number 8710). The leakage tests were performed to supplement the measurements of penetration through the materials, conducted as the first phase of this investigation. The leakage tests were performed with the materials held on to the face by three methods, leakage fractions being determined from comparisons with the penetration of the same aerosol for the materials fully taped to the face. At a breathing rate of 37 liters per minute, mean leakages ranged from 0.0 percent to 63 percent. Mean penetrations exclusive of leakage ranged from 0.6 percent to 39 percent. Use of nylon hosiery material (panty hose) to hold the handkerchief material or the disposable face mask to the face was found to be very effective in preventing leakage. Such a combination could be expected to reduce leakage around the handkerchief to about ten percent or less in practice, and around the mask to less than one percent, offering substantial protection from accidentally generated aerosols. The reduction in leakage around the mask provided by the hosiery material suggests the adaptation and use of such an approach in regular industrial hygiene practice. The third and final phase of this investigation is underway, in which the penetration of the materials by particles with diameters between 0.05 and 0.5 ..mu..m is being measured and the effectiveness of the methods for dose reduction in the presence of radioactive aerosols is being modeled.

  8. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the PTB and the BIPM

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Allisy-Roberts, P. J.; Selbach, H. J.

    2015-01-01

    An indirect comparison of the standards for reference air kerma rate (RAKR) for 192Ir high dose rate (HDR) brachytherapy sources of the Physikalisch-Technische Bundesanstalt (PTB), Germany, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the PTB in September 2011. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the PTB and the BIPM standards for reference air kerma rate, is 1.0003 with a combined standard uncertainty of 0.0099. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  9. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the NRC and the BIPM

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Downton, B.; Mainegra-Hing, E.

    2015-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate (HDR) brachytherapy sources of the National Research Council (NRC), Canada, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the NRC in August 2014. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the NRC and the BIPM standards for reference air kerma rate, is 0.9966 with a combined standard uncertainty of 0.0050. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  10. Comparison BIPM.RI(I)-K8 of high dose-rate Ir-192 brachytherapy standards for reference air kerma rate of the NMIJ and the BIPM

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Kurosawa, T.; Mikamoto, T.

    2016-01-01

    An indirect comparison of the standards for reference air kerma rate for 192Ir high dose rate (HDR) brachytherapy sources of the National Metrology Institute of Japan (AIST-NMIJ), Japan, and of the Bureau International des Poids et Mesures (BIPM) was carried out at the Japan Radioisotope Association (JRIA) in April 2015. The comparison result, based on the calibration coefficients for a transfer standard and expressed as a ratio of the NMIJ and the BIPM standards for reference air kerma rate, is 1.0036 with a combined standard uncertainty of 0.0054. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. Measuring OutdoorAir Intake Rates Using Electronic Velocity Sensors at Louvers and Downstream of Airflow Straighteners

    SciTech Connect

    Fisk, William; Sullivan, Douglas; Cohen, Sebastian; Han, Hwataik

    2008-10-01

    Practical and accurate technologies are needed for continuously measuring and controlling outdoor air (OA) intake rates in commercial building heating, ventilating, and air conditioning (HVAC) systems. This project evaluated two new measurement approaches. Laboratory experiments determined that OA flow rates were measurable with errors generally less than 10percent using electronic air velocity probes installed between OA intake louver blades or at the outlet face of louvers. High accuracy was maintained with OA flow rates as low as 15percent of the maximum for the louvers. Thus, with this measurement approach HVAC systems do not need separate OA intakes for minimum OA supply. System calibration parameters are required for each unique combination of louver type and velocity sensor location but calibrations are not necessary for each system installation. The research also determined that the accuracy of measuring OA flow rates with velocity probes located in the duct downstream of the intake louver was not improved by installing honeycomb airflow straighteners upstream of the probes. Errors varied with type of upstream louver, were as high as 100percent, and were often greater than 25percent. In conclusion, use of electronic air velocity probes between the blades of OA intake louvers or at the outlet face of louvers is a highly promising means of accurately measuring rates of OA flow into HVAC systems. The use of electronic velocity probes downstream of airflow straighteners is less promising, at least with the relatively small OA HVAC inlet systems employed in this research.

  12. Monetizing Leakage Risk of Geologic CO2 Storage using Wellbore Permeability Frequency Distributions

    NASA Astrophysics Data System (ADS)

    Bielicki, Jeffrey; Fitts, Jeffrey; Peters, Catherine; Wilson, Elizabeth

    2013-04-01

    Carbon dioxide (CO2) may be captured from large point sources (e.g., coal-fired power plants, oil refineries, cement manufacturers) and injected into deep sedimentary basins for storage, or sequestration, from the atmosphere. This technology—CO2 Capture and Storage (CCS)—may be a significant component of the portfolio of technologies deployed to mitigate climate change. But injected CO2, or the brine it displaces, may leak from the storage reservoir through a variety of natural and manmade pathways, including existing wells and wellbores. Such leakage will incur costs to a variety of stakeholders, which may affect the desirability of potential CO2 injection locations as well as the feasibility of the CCS approach writ large. Consequently, analyzing and monetizing leakage risk is necessary to develop CCS as a viable technological option to mitigate climate change. Risk is the product of the probability of an outcome and the impact of that outcome. Assessment of leakage risk from geologic CO2 storage reservoirs requires an analysis of the probabilities and magnitudes of leakage, identification of the outcomes that may result from leakage, and an assessment of the expected economic costs of those outcomes. One critical uncertainty regarding the rate and magnitude of leakage is determined by the leakiness of the well leakage pathway. This leakiness is characterized by a leakage permeability for the pathway, and recent work has sought to determine frequency distributions for the leakage permeabilities of wells and wellbores. We conduct a probabilistic analysis of leakage and monetized leakage risk for CO2 injection locations in the Michigan Sedimentary Basin (USA) using empirically derived frequency distributions for wellbore leakage permeabilities. To conduct this probabilistic risk analysis, we apply the RISCS (Risk Interference of Subsurface CO2 Storage) model (Bielicki et al, 2013a, 2012b) to injection into the Mt. Simon Sandstone. RISCS monetizes leakage risk

  13. "Geyser" leakage on fluorescein angiography.

    PubMed

    Levy, Jaime; Fagan, Xavier J; Lifshitz, Tova; Schneck, Marina

    2013-01-01

    An 82-year-old patient with diabetes was followed up due to moderate nonproliferative diabetic retinopathy with macular edema in the right eye. Visual acuity was 6/36. Focal macular laser was conducted (A). Three years later, the patient presented with blurry vision in the right eye. Visual acuity was 3/60. Vitreous hemorrhage was observed (B), and neovascularization of the disc was suspected (C). Fluorescein angiography (D, mid venous phase; E-F, recirculation phase) confirmed neovascularization of the disc and depicted a striking vertical leakage. Panretinal photocoagulation was started. Possible explanations for the "geyser" leakage may be either a partial posterior vitreous detachment allowing the fluorescein to track upwards but not elsewhere or a pocket of syneretic vitreous allowing the fluorescein passage in which to diffuse, much like the passage the blood would have taken. PMID:24548789

  14. Evaluation of leakage from a metal machining center using tracer gas methods: a case study.

    PubMed

    Heitbrink, W A; Earnest, G S; Mickelsen, R L; Mead, K R; D'Arcy, J B

    1999-01-01

    To evaluate the efficacy of engineering controls in reducing worker exposure to metalworking fluids, an evaluation of an enclosure for a machining center during face milling was performed. The enclosure was built around a vertical metal machining center with an attached ventilation system consisting of a 25-cm diameter duct, a fan, and an air-cleaning filter. The evaluation method included using sulfur hexafluoride (SF6) tracer gas to determine the ventilation system's flow rate and capture efficiency, a respirable aerosol monitor (RAM) to identify aerosol leak locations around the enclosure, and smoke tubes and a velometer to evaluate air movement around the outside of the enclosure. Results of the tracer gas evaluation indicated that the control system was approximately 98% efficient at capturing tracer gas released near the spindle of the machining center. This result was not significantly different from 100% efficiency (p = 0.2). The measured SF6 concentration when released directly into the duct had a relative standard deviation of 2.2%; whereas, when releasing SF6 at the spindle, the concentration had a significantly higher relative standard deviation of 7.8% (p = 0.016). This increased variability could be due to a cyclic leakage at a small gap between the upper and lower portion of the enclosure or due to cyclic stagnation. Leakage also was observed with smoke tubes, a velometer, and an aerosol photometer. The tool and fluid motion combined to induce a periodic airflow in and out of the enclosure. These results suggest that tracer gas methods could be used to evaluate enclosure efficiency. However, smoke tubes and aerosol instrumentation such as optical particle counters or aerosol photometers also need to be used to locate leakage from enclosures. PMID:10635544

  15. Nondestructive quantification of leakage at the tooth-composite interface and its correlation with material performance parameters.

    PubMed

    Sun, Jirun; Fang, Rui; Lin, Nancy; Eidelman, Naomi; Lin-Gibson, Sheng

    2009-09-01

    Current methods to determine debonding/leakage at the tooth-composite interface are qualitative or semi-quantitative. Our previous work introduced a 3D imaging technique to determine and visualize leakage and its distribution at the interface of cavity wall and composite restoration in model cavities. In this study, an automated program was developed to quantify leakage in terms of area and volume. 3D leakage distribution obtained via the image analysis program was shown to have excellent agreement with leakage visualized by dye penetration. The relationship between leakage and various material performance parameters including processability, shrinkage, stress, and shrinkage strain-rate was determined using a series of experimental composites containing different filler contents. Results indicate that the magnitude of leakage correlated well with polymerization stress, confirming the validity of the common approach utilizing polymerization stress to predict bonding durability. 3D imaging and image analysis provide insight to help understand the relations between leakage and material properties. PMID:19515419

  16. Comparison of success rate of intubation through Air-Q with ILMA using two different endotracheal tubes

    PubMed Central

    Malhotra, SK; Bharath, KV; Saini, Vikas

    2016-01-01

    Background and Aims: Air-Q™ is a newly introduced airway device, which can be used to facilitate endotracheal intubation. The primary aim of this study was to assess whether use of two different endotracheal tubes (ETTs) (standard polyvinyl chloride [PVC] and reinforced PVC) increases the success rate of blind intubation through Air-Q™ (Group Q) when compared with intubating laryngeal mask airway (ILMA- Fastrach™) keeping ILMA as control (Group I). Methods: One hundred and twenty patients aged between 18 and 60 years with American Society of Anesthesiologists physical status I-II, undergoing elective surgery under general anaesthesia, were enrolled into this prospective, randomised, case–control study to compare the success rate of tracheal intubation between ILMA (Fastrach™) and Air-Q™ intubating laryngeal airway. Those patients with anticipated difficult airway were excluded from the study. All the recruited patients completed the study. Reinforced PVC ETT was used in both airway devices to secure intubation. Since standard PVC tube is recommended for use in Air-Q, when first intubation attempt failed, second or third attempt was made with standard PVC ETT. Total of three attempts were made for each procedure: Whereas in ILMA group, only reinforced tube was used in all three attempts. Results: The overall success rate after three attempts was more with Air-Q (96.6%) in our study compared with ILMA (91.6%) but no significant difference was seen between the groups (P = 0.43). Conclusion: The present study shows that when intubation with reinforced tube fails, the success rate with use of conventional PVC tube is more with Air-Q when compared with ILMA. PMID:27141106

  17. CHANGES IN HEART RATE VARIABILITY AND LUNG FUNCTION OBSERVED IN NC PATROL TROOPERS EXPOSED TO PM AND AIR TOXICS

    EPA Science Inventory

    Changes in Heart Rate Variability and Lung Function in NC Patrol Troopers exposed to PM and Air Toxics

    Michael Riediker1, Wayne E Cascio1, Robert B Devlin2, Thomas Griggs1&4, Margaret Herbst1, Ronald W Williams3, Steve P McCorquodale4, Philip A Bromberg1
    1) University o...

  18. INVESTIGATING THE INFLUENCE OF RELATIVE HUMIDITY, AIR VELOCITY, AND AMPLIFICATION ON THE EMISSION RATES OF FUNGAL SPORES

    EPA Science Inventory

    The paper discusses the impact of relative humidity (RH), air velocity, and surface growth on the emission rates of fungal spores from the surface of contaminated material. Although the results show a complex interaction of factors, we have determined, for this limited data set,...

  19. EFFECT OF VENTILATION SYSTEMS AND AIR FILTERS ON DECAY RATES OF PARTICLES PRODUCED BY INDOOR SOURCES IN AN OCCUPIED TOWNHOUSE

    EPA Science Inventory

    Several studies have shown the importance of particle losses in real homes due to deposition and filtration; however, none have quantitatively shown the impact of using a central forced air fan and in-duct filter on particle loss rates. In an attempt to provide such data, we me...

  20. Development and Evaluation of a New Air Exchange Rate Algorithm for the Stochastic Human Exposure and Dose Simulation Model

    EPA Science Inventory

    between-home and between-city variability in residential pollutant infiltration. This is likely a result of differences in home ventilation, or air exchange rates (AER). The Stochastic Human Exposure and Dose Simulation (SHEDS) model is a population exposure model that uses a pro...

  1. Is volcanic air pollution associated with decreased heart-rate variability?

    PubMed

    Chow, Dominic C; Grandinetti, Andrew; Fernandez, Ed; Sutton, A J; Elias, Tamar; Brooks, Barbara; Tam, Elizabeth K

    2010-02-23

    OBJECTIVES: To determine the autonomic cardiovascular control among residents of Hawaii who are exposed to varying levels of volcanic air pollution (vog), which consists largely of sulfur dioxide (SO(2)) and acid aerosols. METHODS: In a cross-sectional study between April 2006 and June 2008, the authors measured cardiovagal autonomic function by heart-rate variability (HRV) in 72 healthy individuals who lived in four exposure zones on Hawaii Island: vog-free (n=18); episodic exposure to SO(2) >200 ppb and acid aerosol (n=19); chronic exposure to SO(2) ≥30 ppb and acid aerosol (n=15); and chronic exposure to acid aerosols (n=20). Individuals with diabetes or heart disease, or who had smoked in the preceding month were excluded. HRV was measured in all subjects during rest, paced breathing and active standing (Ewing manoeuvre). HRV was analysed in time and frequency domains and compared between the four exposure zones. RESULTS: There were no significant differences between exposure zones in HRV, in either time or frequency domains, even after adjustment for age, gender, ethnicity and body mass index. There was no significant HRV change in three individuals in whom HRV was measured before and during an exposure to combined SO(2) 100-250 ppb and concentration of respirable particles of diameter ≥2.5 μ (PM(2.5)) >500 μg/m(3). Age was significantly correlated with time-domain parameters during paced breathing and the Ewing manoeuvre. CONCLUSIONS: This study of healthy individuals found no appreciable effects of vog on the autonomic nervous system. PMID:21546995

  2. Reference dosimetry at the Australian Synchrotron's imaging and medical beamline using free-air ionization chamber measurements and theoretical predictions of air kerma rate and half value layer

    SciTech Connect

    Crosbie, Jeffrey C.; Rogers, Peter A. W.; Stevenson, Andrew W.; Hall, Christopher J.; Lye, Jessica E.; Nordstroem, Terese; Midgley, Stewart M.; Lewis, Robert A.

    2013-06-15

    Purpose: Novel, preclinical radiotherapy modalities are being developed at synchrotrons around the world, most notably stereotactic synchrotron radiation therapy and microbeam radiotherapy at the European Synchrotron Radiation Facility in Grenoble, France. The imaging and medical beamline (IMBL) at the Australian Synchrotron has recently become available for preclinical radiotherapy and imaging research with clinical trials, a distinct possibility in the coming years. The aim of this present study was to accurately characterize the synchrotron-generated x-ray beam for the purposes of air kerma-based absolute dosimetry. Methods: The authors used a theoretical model of the energy spectrum from the wiggler source and validated this model by comparing the transmission through copper absorbers (0.1-3.0 mm) against real measurements conducted at the beamline. The authors used a low energy free air ionization chamber (LEFAC) from the Australian Radiation Protection and Nuclear Safety Agency and a commercially available free air chamber (ADC-105) for the measurements. The dimensions of these two chambers are different from one another requiring careful consideration of correction factors. Results: Measured and calculated half value layer (HVL) and air kerma rates differed by less than 3% for the LEFAC when the ion chamber readings were corrected for electron energy loss and ion recombination. The agreement between measured and predicted air kerma rates was less satisfactory for the ADC-105 chamber, however. The LEFAC and ADC measurements produced a first half value layer of 0.405 {+-} 0.015 and 0.412 {+-} 0.016 mm Cu, respectively, compared to the theoretical prediction of 0.427 {+-} 0.012 mm Cu. The theoretical model based upon a spectrum calculator derived a mean beam energy of 61.4 keV with a first half value layer of approximately 30 mm in water. Conclusions: The authors showed in this study their ability to verify the predicted air kerma rate and x-ray attenuation

  3. An Explanation of the Varied Measurements of Gas Field Methane Leakage

    NASA Astrophysics Data System (ADS)

    Evans, W. F.; McHugh, M. J.

    2014-12-01

    In situ engineering measurements of natural gas well sites indicate leakage rates with a mean rate of 1.5% of the gas production rate from individual wells. These have been made at several gas basins using in situ measurements. These in situ engineering measurements are reported as the fugitive emission rates to the UNCCC by the EPA. On the other hand, atmospheric measurements at altitudes above the surface by several atmospheric groups indicate that gas fields are leaking at an average rate of over 9 %. Papers have been published in several highly reputable journals by government and university scientists. Both groups have been criticizing the methodologies of the opposite group. We propose that a more likely explanation is that both groups are correct. Although this appears as a direct conflict with one group on each side, a careful analysis shows that the two groups are measuring different air parcels. This is the only explanation which will explain the apparent conflicting situation. This can be understood if the basins in which the wells are sited are actually leaking from the bed rock formations in which the wells are drilled. If the geology of the natural gas basins is examined in detail, then the situation becomes understandable. Many basins contain gas in fault traps. These faults often leak, particularly if there is a small earthquake. The leaks can follow tilted layers, resulting in vertical transport of gas along the slanted layer cracks. This leakage may emerge into the atmosphere at large distances from the actual gas well under measurement. Fracking can obviously increase the leakage from a valley gas field. The methane leaks could alter the budgets of greenhouse gases reported by various gas producing countries by significant amounts. The potential increases and altered budgets for various countries as reported to the UNCCC are estimated and reported in this presentation. The fraction of these unreported leaks which should be reported will have to

  4. The air dose rate around the Fukushima Dai-ichi Nuclear Power Plant: its spatial characteristics and temporal changes until December 2012.

    PubMed

    Mikami, Satoshi; Maeyama, Takeshi; Hoshide, Yoshifumi; Sakamoto, Ryuichi; Sato, Shoji; Okuda, Naotoshi; Sato, Tetsuro; Takemiya, Hiroshi; Saito, Kimiaki

    2015-01-01

    Distribution maps of air dose rates around the Fukushima Dai-ichi Nuclear Power Plant were constructed using the results of measurement obtained from approximately 6500 locations (at most) per measurement period. The measurements were conducted 1 m above the ground using survey meters in flat and spatially open locations. Spatial distribution and temporal change of the air dose rate in the area were revealed by examining the resultant distribution maps. The observed reduction rate of the air dose rate over the 18 months between June 2011 and December 2012 was greater than that calculated from radioactive decay of radiocesium by 10% in relative percentage except decontaminated sites. This 10% difference in the reduction of the air dose rate can be explained by the mobility of radiocesium in the depth direction. In the region where the air dose rate was lower than 0.25 μSv h(-1) on June 2011, the reduction of the air dose rate was observed to be smaller than that of the other dose rate regions, and it was in fact smaller than the reduction rate caused by radioactive decay alone. In contrast, the reduction rate was larger in regions with higher air dose rates. In flat and spatially open locations, no significant difference in the reduction tendency of air dose rates was observed among different land use classifications (rice fields, farmland, forests, and building sites). PMID:25246092

  5. Method of detecting leakage from geologic formations used to sequester CO.sub.2

    SciTech Connect

    White, Curt; Wells, Arthur; Diehl, J. Rodney; Strazisar, Brian

    2010-04-27

    The invention provides methods for the measurement of carbon dioxide leakage from sequestration reservoirs. Tracer moieties are injected along with carbon dioxide into geological formations. Leakage is monitored by gas chromatographic analyses of absorbents. The invention also provides a process for the early leak detection of possible carbon dioxide leakage from sequestration reservoirs by measuring methane (CH.sub.4), ethane (C.sub.2H.sub.6), propane (C.sub.3H.sub.8), and/or radon (Rn) leakage rates from the reservoirs. The invention further provides a method for branding sequestered carbon dioxide using perfluorcarbon tracers (PFTs) to show ownership.

  6. Semianalytical solution for CO2 leakage through an abandoned well.

    PubMed

    Nordbotten, Jan Martin; Celia, Michael A; Bachu, Stefan; Dahle, Helge K

    2005-01-15

    Capture and subsequent injection of carbon dioxide into deep geological formations is being considered as a means to reduce anthropogenic emissions of CO2 to the atmosphere. If such a strategy is to be successful, the injected CO2 must remain within the injection formation for long periods of time, at least several hundred years. Because mature continental sedimentary basins have a century-long history of oil and gas exploration and production, they are characterized by large numbers of existing oil and gas wells. For example, more than 1 million such wells have been drilled in the state of Texas in the United States. These existing wells represent potential leakage pathways for injected CO2. To analyze leakage potential, modeling tools are needed that predict leakage rates and patterns in systems with injection and potentially leaky wells. A new semianalytical solution framework allows simple and efficient prediction of leakage rates for the case of injection of supercritical CO2 into a brine-saturated deep aquifer. The solution predicts the extent of the injected CO2 plume, provides leakage rates through an abandoned well located at an arbitrary distance from the injection well, and estimates the CO2 plume extent in the overlying aquifer into which the fluid leaks. Comparison to results from a numerical multiphase flow simulator show excellent agreement. Example calculations show the importance of outer boundary conditions, the influence of both density and viscosity contrasts in the resulting solutions, and the potential importance of local upconing around the leaky well. While several important limiting assumptions are required, the new semianalytical solution provides a simple and efficient procedure for estimation of CO2 leakage for problems involving one injection well, one leaky well, and multiple aquifers separated by impermeable aquitards. PMID:15707061

  7. Impact of energy-conserving retrofits on indoor air quality in residental housing

    SciTech Connect

    Berk, J.V.; Young, R.A.; Brown, S.R.; Hollowell, C.D.

    1981-01-01

    The impact of energy-conservation retrofits on the indoor air quality of residential buildings is being assessed through a field-monitoring project in which air leakage, air exchange rates, and indoor air pollutants are measured before and after retrofit measures are implemented. A mobile laboratory was used to make detailed on-site measurements of air exchange rate and concentrations of radon, formaldehyde, total aldehydes, particulates, carbon dioxide, carbon monoxide, nitrogen dioxide, nitric oxide, ozone, and sulfur dioxide in two houses and effective leakage area measurements were made in seven others. Results from the nine houses studied here show that the impact of energy-conserving retrofits depends on (1) the type and extent of the retrofit, (2) the operating characteristics of the heating/cooling system, and (3) the activities of the occupants.

  8. [Effects of air pollution on stillbirth rates in an industrial town].

    PubMed

    Dimitriev, D A

    2000-01-01

    The impact of seasonal variations in ambient air pollution with some compounds (suspended matters, sulphur dioxide, carbon oxide, nitrogen dioxide) on stillbirth was studied. Changes in the concentration of the studied pollutants were found to affect stillbirth. PMID:11030098

  9. Authentic Assessment in the Geometry Classroom: Calculating the Classroom Air-Exchange Rate.

    ERIC Educational Resources Information Center

    Erich, David J.

    2002-01-01

    Introduces a room air-exchange activity designed to assess student understanding of the concept of volume. Lists materials for the activity and its procedures. Includes the lesson plan and a student worksheet. (KHR)

  10. Impact of Blow/Fill/Seal process variables in determining rate of vial contamination by air dispersed microorganisms.

    PubMed

    Leo, Frank; Poisson, Patrick; Sinclair, Colin S; Tallentire, Alan

    2005-01-01

    Controlled challenges of air dispersed spores of Bacillus subtilis NCIMB 8649 have been generated in a custom-built challenge room housing a Blow/Fill/Seal machine filling filter-sterilized trypticase soy broth into 5.5 cm3 low density polyethylene vials. The effects on the rate of vial contamination of systematic changes in the process variables, rate of provision of ballooning air, delay in the application of mould vacuum and duration of transfer of the open vial, have been examined. Overall, the findings show that the conditions of vial formation can affect appreciably the rate of vial contamination from airborne spores. The indications are that heat lethality, associated with the elevated temperature required for polymer extrusion and vial formation, has a role in determining such contamination. PMID:16316067

  11. Microvascular leakage of plasma proteins after PUVA and UVA

    SciTech Connect

    Staberg, B.; Worm, A.M.; Rossing, N.; Brodthagen, H.

    1982-04-01

    The transcapillary escape rate of albumin (TERalb), is a parameter of the leakage of macromolecules from the total microvasculature. In patients with psoriasis short-term PUVA treatment induces an increase in TERalb. In this study TERalb was measured in 3 groups of normal humans treated with PUVA, UVA and 8-methoxypsoralen. Treatment with PUVA and UVA caused a statistically significant increase in TERalb, whereas treatment with 8-methoxypsoralen did not induce any measurable changes. It is concluded that the UVA irradiation causes the abnormal leakage of macromolecules, whereas psoralen is not the responsible component. Furthermore the phenomenon can be elicited in normals and is not based on a preexisting psoriasis.

  12. Measurement of HO{sub x}{center_dot} production rate due to radon decay in air

    SciTech Connect

    Ding, Huiling

    1993-08-01

    Radon in indoor air may cause the exposure of the public to excessive radioactivity. Radiolysis of water vapor in indoor air due to radon decay could produce ({center_dot}OH and HO{sub 2} {center_dot}) that may convert atmospheric constituents to compounds of lower vapor pressure. These lower vapor pressure compounds might then nucleate to form new particles in the indoor atmosphere. Chemical amplification was used to determine HO{sub x}{center_dot} production rate in indoor air caused by radon decay. Average HO{sub x}{center_dot} production rate was found to be (4.31{plus_minus}0.07) {times} 10{sup 5} HO{sub x}{center_dot} per Rn decay per second (Bq) 3.4 to 55.0% at 22C. This work provided G{sub (HO{sub x}{center_dot})}-value, 7.86{plus_minus}0.13 No./100 eV in air by directly measuring [HO{sub x}{center_dot}] formed from the radiolysis procedure. This G value implies that HO{sub x}{center_dot} produced by radon decay in air might be formed by multiple processes and may be result of positive ion-molecule reactions, primary radiolysis, and radical reactions. There is no obvious relation between HO{sub x}{center_dot} production rate and relative humidity. A laser-induced fluorescence (LIF) system has been used for {center_dot}OH production rate measurement; it consists of an excimer laser, a dye laser, a frequency doubler, a gaseous fluorescence chamber, and other optical and electronic parts. This system needs to be improved to eliminate the interferences of light scattering and artificial {center_dot}OH produced from the photolysis of O{sub 3}/H{sub 2}O.

  13. Leakage Characteristics of Dual-Cannula Fenestrated Tracheostomy Tubes during Positive Pressure Ventilation: A Bench Study.

    PubMed

    Berlet, Thomas; Marchon, Mathias

    2016-01-01

    This study compared the leakage characteristics of different types of dual-cannula fenestrated tracheostomy tubes during positive pressure ventilation. Fenestrated Portex® Blue Line Ultra®, TRACOE® twist, or Rüsch® Traceofix® tracheostomy tubes equipped with nonfenestrated inner cannulas were tested in a tracheostomy-lung simulator. Transfenestration pressures and transfenestration leakage rates were measured during positive pressure ventilation. The impact of different ventilation modes, airway pressures, temperatures, and simulated static lung compliance settings on leakage characteristics was assessed. We observed substantial differences in transfenestration pressures and transfenestration leakage rates. The leakage rates of the best performing tubes were <3.5% of the delivered minute volume. At body temperature, the leakage rates of these tracheostomy tubes were <1%. The tracheal tube design was the main factor that determined the leakage characteristics. Careful tracheostomy tube selection permits the use of fenestrated tracheostomy tubes in patients receiving positive pressure ventilation immediately after stoma formation and minimises the risk of complications caused by transfenestration gas leakage, for example, subcutaneous emphysema. PMID:27073395

  14. Leakage Characteristics of Dual-Cannula Fenestrated Tracheostomy Tubes during Positive Pressure Ventilation: A Bench Study

    PubMed Central

    2016-01-01

    This study compared the leakage characteristics of different types of dual-cannula fenestrated tracheostomy tubes during positive pressure ventilation. Fenestrated Portex® Blue Line Ultra®, TRACOE® twist, or Rüsch® Traceofix® tracheostomy tubes equipped with nonfenestrated inner cannulas were tested in a tracheostomy-lung simulator. Transfenestration pressures and transfenestration leakage rates were measured during positive pressure ventilation. The impact of different ventilation modes, airway pressures, temperatures, and simulated static lung compliance settings on leakage characteristics was assessed. We observed substantial differences in transfenestration pressures and transfenestration leakage rates. The leakage rates of the best performing tubes were <3.5% of the delivered minute volume. At body temperature, the leakage rates of these tracheostomy tubes were <1%. The tracheal tube design was the main factor that determined the leakage characteristics. Careful tracheostomy tube selection permits the use of fenestrated tracheostomy tubes in patients receiving positive pressure ventilation immediately after stoma formation and minimises the risk of complications caused by transfenestration gas leakage, for example, subcutaneous emphysema. PMID:27073395

  15. Leakage testing of packagings with three-O-ring closure seals

    SciTech Connect

    Oras, J.J.; Towell, R.H.; Wangler, M.E.

    1997-10-01

    Both the American National Standard for Radioactive Materials--Leakage Tests on Packages for Shipment (ANSI N14.5) and the ISO 12807:1996 Safe Transport of Radioactive Materials--Leakage Testing on Packages provide guidance for leakage rate testing to show that a particular packaging complies with regulatory requirements; both also provide guidance for determining appropriate acceptance criteria. Recent radioactive packaging designs have incorporated three-O-ring closure seals, the middle O-ring being the containment seal. These designs have the potential for false positive results in leakage rate tests. The volume between the containment O-ring and the inner O-ring is used for the helium gas required for the leakage rate tests, in order to reduce both the amount of helium used and the time required to conduct the tests. A leak detector samples the evacuated volume between the outer O-ring and the containment O-ring. False positive results can have two causes: a large leakage in the containment seal or leakage in the inner seal. This paper describes the problem, together with possible solutions and areas that should be addressed in a Safety Analysis Report for Packaging (SARP) before a particular packaging design can be certified for transport. Ultimately, the SARP should provide justification that the requirements for leakage rate testing procedures, including the length of time needed to conduct the tests, will ensure that the containment closure seal is properly tested.

  16. Blower-door techniques for measuring interzonal leakage

    SciTech Connect

    Hult, Erin L.; Sherman, Max H.; Walker, Iain

    2013-01-01

    Abstract The standard blower door test methods, such as ASTM E779, describe how to use a single blower door to determine the total leakage of a single-zone structure such as a detached single-family home. There are no standard test methods for measuring interzonal leakage in a two-zone or multi-zone building envelope such as might be encountered in with an attached garage or in a multifamily building. Some practitioners have been using techniques that involve making multiple measurements with a single blower door as well as combined measurements using multiple blower doors. Even for just two zones there are dozens of combinations of one-door and two-door test protocols that could conceivably be used to determine the interzonal air tightness. We examined many of these two-zone configurations using both simulation and measured data to estimate the accuracy and precision of each technique for realistic measurement scenarios. We also considered the impact of taking measurements at a single pressure versus over multiple pressures. We compared the various techniques and evaluated them for specific uses. Some techniques work better in one leakage regime; some are more sensitive to wind and other noise; some are more suited to determining only a subset of the leakage values. This paper makes recommendations on which techniques to use or not use for various cases and provides data that could be used to develop future test methods.

  17. Characteristics and verification of a car-borne survey system for dose rates in air: KURAMA-II.

    PubMed

    Tsuda, S; Yoshida, T; Tsutsumi, M; Saito, K

    2015-01-01

    The car-borne survey system KURAMA-II, developed by the Kyoto University Research Reactor Institute, has been used for air dose rate mapping after the Fukushima Dai-ichi Nuclear Power Plant accident. KURAMA-II consists of a CsI(Tl) scintillation detector, a GPS device, and a control device for data processing. The dose rates monitored by KURAMA-II are based on the G(E) function (spectrum-dose conversion operator), which can precisely calculate dose rates from measured pulse-height distribution even if the energy spectrum changes significantly. The characteristics of KURAMA-II have been investigated with particular consideration to the reliability of the calculated G(E) function, dose rate dependence, statistical fluctuation, angular dependence, and energy dependence. The results indicate that 100 units of KURAMA-II systems have acceptable quality for mass monitoring of dose rates in the environment. PMID:24698118

  18. Effect of ambient air pollution on daily mortality rates in Guangzhou, China

    NASA Astrophysics Data System (ADS)

    Yu, Ignatius Tak Sun; Zhang, Yong hui; San Tam, Wilson Wai; Yan, Qing Hua; Xu, Yan jun; Xun, Xiao jun; Wu, Wei; Ma, Wen Jun; Tian, Lin Wei; Tse, Lap Ah; Lao, Xiang Qian

    2012-01-01

    We aimed to investigate the effects of ambient air pollutants on daily mortality in a relatively stable and homogeneous population in Guangzhou, China. Daily mortality, air pollution, and weather data between 2006 and 2009 were collected. The generalized additive model with poison regression was used to estimate the excessive risks (ERs) of air pollutants (PM 10, SO 2, and NO 2) on total, cardiovascular and respiratory mortality. The effects of lag0-1 were the greatest for total non-accidental and cardiovascular deaths. The increments of 10 μg m -3 in SO 2, NO 2, and PM 10 were associated with ERs of 1.54% (95%CI: 1.03-2.06%), 1.42% (95%CI: 1.06-1.78%), and 1.26% (95%CI: 0.86-1.66%) respectively for total non-accidental deaths, and 2.28% (95%CI: 1.40-3.16%), 1.81% (95%CI: 1.20-2.41%), and 1.79% (95%CI: 1.11-2.47%) respectively for cardiovascular deaths. For persons who died from respiratory disease, however, the maximum effects occurred at lag0. The ERs for SO 2, NO 2, and PM 10 were 1.36% (95%CI: 0.23-2.50%), 1.47% (95%CI: 0.66-2.29%) and 0.93% (95%CI: 0.03-1.83%), respectively. The effects of the three air pollutants on mortality were stronger in elderly and in women. The ERs in the present study were higher than those reported in Europe, the U.S., and most other Asian cities. Our findings show relatively higher ERs of daily mortality by ambient air pollutants in the center of Guangzhou, China, compared with estimates in other cities. Further studies with accurate exposure measurement among homogeneous population are needed to evaluate the precise magnitudes of the effects of the air pollutants.

  19. Regional Contrasts of the Warming Rate over Land Significantly Depend on the Calculation Methods of Mean Air Temperature

    PubMed Central

    Wang, Kaicun; Zhou, Chunlüe

    2015-01-01

    Global analyses of surface mean air temperature (Tm) are key datasets for climate change studies and provide fundamental evidences for global warming. However, the causes of regional contrasts in the warming rate revealed by such datasets, i.e., enhanced warming rates over the northern high latitudes and the “warming hole” over the central U.S., are still under debate. Here we show these regional contrasts depend on the calculation methods of Tm. Existing global analyses calculate Tm from daily minimum and maximum temperatures (T2). We found that T2 has a significant standard deviation error of 0.23 °C/decade in depicting the regional warming rate from 2000 to 2013 but can be reduced by two-thirds using Tm calculated from observations at four specific times (T4), which samples diurnal cycle of land surface air temperature more often. From 1973 to 1997, compared with T4, T2 significantly underestimated the warming rate over the central U.S. and overestimated the warming rate over the northern high latitudes. The ratio of the warming rate over China to that over the U.S. reduces from 2.3 by T2 to 1.4 by T4. This study shows that the studies of regional warming can be substantially improved by T4 instead of T2. PMID:26198976

  20. Regional Contrasts of the Warming Rate over Land Significantly Depend on the Calculation Methods of Mean Air Temperature

    NASA Astrophysics Data System (ADS)

    Wang, Kaicun; Zhou, Chunlüe

    2015-07-01

    Global analyses of surface mean air temperature (Tm) are key datasets for climate change studies and provide fundamental evidences for global warming. However, the causes of regional contrasts in the warming rate revealed by such datasets, i.e., enhanced warming rates over the northern high latitudes and the “warming hole” over the central U.S., are still under debate. Here we show these regional contrasts depend on the calculation methods of Tm. Existing global analyses calculate Tm from daily minimum and maximum temperatures (T2). We found that T2 has a significant standard deviation error of 0.23 °C/decade in depicting the regional warming rate from 2000 to 2013 but can be reduced by two-thirds using Tm calculated from observations at four specific times (T4), which samples diurnal cycle of land surface air temperature more often. From 1973 to 1997, compared with T4, T2 significantly underestimated the warming rate over the central U.S. and overestimated the warming rate over the northern high latitudes. The ratio of the warming rate over China to that over the U.S. reduces from 2.3 by T2 to 1.4 by T4. This study shows that the studies of regional warming can be substantially improved by T4 instead of T2.

  1. Regional Contrasts of the Warming Rate over Land Significantly Depend on the Calculation Methods of Mean Air Temperature

    NASA Astrophysics Data System (ADS)

    Wang, Kaicun; Zhou, Chunlüe

    2016-04-01

    Global analyses of surface mean air temperature (Tm) are key datasets for climate change studies and provide fundamental evidences for global warming. However, the causes of regional contrasts in the warming rate revealed by such datasets, i.e., enhanced warming rates over the northern high latitudes and the "warming hole" over the central U.S., are still under debate. Here we show these regional contrasts depends on the calculation methods of Tm. Existing global analyses calculated Tm from daily minimum and maximum temperatures (T2). We found that T2 has a significant standard deviation error of 0.23 °C/decade in depicting the regional warming rate from 2000 to 2013 but can be reduced by two-thirds using Tm calculated from observations at four specific times (T4), which samples diurnal cycle of land surface air temperature more often. From 1973 to 1997, compared with T4, T2 significantly underestimated the warming rate over the central U.S. and overestimated the warming rate over the northern high latitudes. The ratio of the warming rate over China to that over the U.S. reduces from 2.3 by T2 to 1.4 by T4. This study shows that the studies of regional warming can be substantially improved by T4 instead of T2.

  2. Regional Contrasts of the Warming Rate over Land Significantly Depend on the Calculation Methods of Mean Air Temperature.

    PubMed

    Wang, Kaicun; Zhou, Chunlüe

    2015-01-01

    Global analyses of surface mean air temperature (T(m)) are key datasets for climate change studies and provide fundamental evidences for global warming. However, the causes of regional contrasts in the warming rate revealed by such datasets, i.e., enhanced warming rates over the northern high latitudes and the "warming hole" over the central U.S., are still under debate. Here we show these regional contrasts depend on the calculation methods of T(m). Existing global analyses calculate T(m) from daily minimum and maximum temperatures (T2). We found that T2 has a significant standard deviation error of 0.23 °C/decade in depicting the regional warming rate from 2000 to 2013 but can be reduced by two-thirds using T(m) calculated from observations at four specific times (T4), which samples diurnal cycle of land surface air temperature more often. From 1973 to 1997, compared with T4, T2 significantly underestimated the warming rate over the central U.S. and overestimated the warming rate over the northern high latitudes. The ratio of the warming rate over China to that over the U.S. reduces from 2.3 by T2 to 1.4 by T4. This study shows that the studies of regional warming can be substantially improved by T4 instead of T2. PMID:26198976

  3. Leakage effects in car underhood aerothermal management: temperature and heat flux analysis

    NASA Astrophysics Data System (ADS)

    Khaled, Mahmoud; Habchi, Charbel; Harambat, Fabien; Elmarakbi, Ahmed; Peerhossaini, Hassan

    2014-10-01

    Air leakage from the engine compartment of a vehicle comes mainly from the junctions of the vehicle hood and the front end grill, the vehicle wings, the optical and the windshield. The present paper studies the thermal impact of these air leakage zones on the components of the vehicle engine compartment through temperature and heat-flux measurements. The front wheels of the test vehicle are positioned on a dynamometer and driven by the vehicle engine. The engine compartment is instrumented with almost 100 surface and air thermocouples and 20 fluxmeters of normal gradients. Measurements were made for three different thermal operating points. Five leak-sealing configurations are studied.

  4. Particle size-dependent leakage and losses of aerosols in respirators.

    PubMed

    Holton, P M; Tackett, D L; Willeke, K

    1987-10-01

    Measuring particle size-dependent leakage into and losses inside a respirator reveals the deposition mechanisms occurring at the leak site and the flow dynamics inside the respirator. This study investigated particle size-dependent leakage and deposition within the mask by examining the leakage into the mask for different hole locations, probe locations, hole shapes, hole lengths and hole sizes. The shape of the leak has an effect on particle size-dependent leakage. Probe and leak location tests indicated that not only does the total measured leakage change but also the size-dependence of the leakage changes depending on the leak and probe locations. When the leak site is in the chin area, the clean air entering through the filters at the chin helps to carry the inward leakage into the breathing zone. Particle size-dependent leakage does occur and is due to both inertial entry losses at the leak site and within the mask, and diffusional losses within the mask and leak site. Particle size-dependent curves change shape as the hole size changes with relatively more larger particles entering through the small hole size. PMID:3687729

  5. THE EFFECT OF SALINITY ON RATES OF ELEMENTAL MERCURY AIR/WATER EXCHANGE

    EPA Science Inventory

    The U.S. EPA laboratory in Athens, Georgia i spursuing the goal of developing a model for describing toxicant vapor phase air/water exchange under all relevant environmental conditions. To date, the two-layer exchange model (suitable for low wind speed conditions) has been modif...

  6. Elementary stage rate coefficients of heterogeneous catalytic recombination of dissociated air on thermal protective surfaces from ab initio approach

    NASA Astrophysics Data System (ADS)

    Buchachenko, A. A.; Kroupnov, A. A.; Kovalev, V. L.

    2015-08-01

    Elementary stage rate coefficients of the full system of kinetic equations describing heterogeneous catalytic recombination of the dissociated air on the surfaces of thermal protective ceramic coatings of β-cristobalite and α-Al2O3 are determined using the quantum-mechanical calculations within the framework of cluster models and literature data. Both the impact and associative recombination processes of adsorbed oxygen and nitrogen atoms are taken into account.

  7. Lower responsiveness of canopy evapotranspiration rate than of leaf stomatal conductance to open-air CO2 elevation in rice.

    PubMed

    Shimono, Hiroyuki; Nakamura, Hirofumi; Hasegawa, Toshihiro; Okada, Masumi

    2013-08-01

    An elevated atmospheric CO2 concentration ([CO2 ]) can reduce stomatal conductance of leaves for most plant species, including rice (Oryza sativa L.). However, few studies have quantified seasonal changes in the effects of elevated [CO2 ] on canopy evapotranspiration, which integrates the response of stomatal conductance of individual leaves with other responses, such as leaf area expansion, changes in leaf surface temperature, and changes in developmental stages, in field conditions. We conducted a field experiment to measure seasonal changes in stomatal conductance of the uppermost leaves and in the evapotranspiration, transpiration, and evaporation rates using a lysimeter method. The study was conducted for flooded rice under open-air CO2 elevation. Stomatal conductance decreased by 27% under elevated [CO2 ], averaged throughout the growing season, and evapotranspiration decreased by an average of 5% during the same period. The decrease in daily evapotranspiration caused by elevated [CO2 ] was more significantly correlated with air temperature and leaf area index (LAI) rather than with other parameters of solar radiation, days after transplanting, vapor-pressure deficit and FAO reference evapotranspiration. This indicates that higher air temperatures, within the range from 16 to 27 °C, and a larger LAI, within the range from 0 to 4 m(2)  m(-2) , can increase the magnitude of the decrease in evapotranspiration rate caused by elevated [CO2 ]. The crop coefficient (i.e. the evapotranspiration rate divided by the FAO reference evapotranspiration rate) was 1.24 at ambient [CO2 ] and 1.17 at elevated [CO2 ]. This study provides the first direct measurement of the effects of elevated [CO2 ] on rice canopy evapotranspiration under open-air conditions using the lysimeter method, and the results will improve future predictions of water use in rice fields. PMID:23564676

  8. Building America Case Study: Challenges of Achieving 2012 IECC Air Sealing Requirements in Multifamily Dwellings, Upstate New York (Fact Sheet)

    SciTech Connect

    Not Available

    2014-11-01

    While previous versions of the International Energy Conservation Code (IECC) have included provisions to improve the air tightness of dwellings, for the first time, the 2012 IECC mandates compliance verification through blower door testing. Simply completing the Air Barrier and Insulation Installation checklist through visual inspection is no longer sufficient by itself. In addition, the 2012 IECC mandates a significantly stricter air sealing requirement. In Climate Zones 3 through 8, air leakage may not exceed 3 ACH50, which is a significant reduction from the 2009 IECC requirement of 7 ACH50. This requirement is for all residential buildings, which includes low-rise multifamily dwellings. While this air leakage rate requirement is an important component to achieving an efficient building thermal envelope, currently, the code language doesn't explicitly address differences between single family and multifamily applications. In addition, the 2012 IECC does not provide an option to sample dwellings for larger multifamily buildings, so compliance would have to be verified on every unit. With compliance with the 2012 IECC air leakage requirements on the horizon, several of CARB's multifamily builder partners are evaluating how best to comply with this requirement. Builders are not sure whether it is more practical or beneficial to simply pay for guarded testing or to revise their air sealing strategies to improve compartmentalization to comply with code requirements based on unguarded blower door testing. This report summarizes CARB's research that was conducted to assess the feasibility of meeting the 2012 IECC air leakage requirements in 3 multifamily buildings.

  9. Indoor air exposure to coal and wood combustion emissions associated with a high lung cancer rate in Xuan Wei, China

    SciTech Connect

    Mumford, J.L.; Chapman, R.S.; Harris, D.B.; He, X.Z.; Cac, S.R.

    1989-01-01

    Residents of Xuan Wei County in China have unusually high lung cancer mortality that cannot be attributed to tobacco use or occupational exposure. They are exposed to smoke from unvented, open pit coal or wood fires (often used for cooking and heating). The variation in lung cancer rates among communes within the county suggests that indoor combustion of smoky coal may be the prime determinant of lung cancer. To characterize the air in Xuan Wei homes, samples of the air particles and semivolatile organic compounds were collected from homes located in two communes; one commune has a high rate of lung cancer, and the other has a low rate. Samples collected in the commune where the lung cancer rate is high and where smoky coal is the predominant fuel contained high concentrations of small particles with high organic content; organic extracts of these samples were mutagenic. Samples from homes in the wood-burning commune, which has a low rate of lung cancer, consisted mostly of larger particles of lower organic content and mutagenicity. The smoky coal sample was a mouse skin carcinogen and was a more potent initiator of skin tumors in comparison to the wood or smokeless coal sample.

  10. Indoor air exposure to coal and wood combustion emissions associated with a high lung cancer rate in Xuan Wei, China

    SciTech Connect

    Mumford, J.L.; Chapman, R.S.; Harris, D.B. ); He, X.Z.; Cao, S.R.; Xian, Y.L.; Li, X.M. )

    1989-01-01

    Residents of Xuan Wei County in China have unusually high lung cancer mortality that cannot be attributed to tobacco use or occupational exposure. They are exposed to smoke from unvented, open pit coal or wood fires (often used for cooking and heating). The variation in lung cancer rates among communes within the county suggests that indoor combustion of smoky coal may be the prime determinant of lung cancer. To characterize the air in Xuan Wei homes, samples of air particles and semivolatile organic compounds were collected from homes located in two communes; one commune has a high rate of lung cancer, and the other has a low rate. Samples collected in the commune where the lung cancer rate is high and where smoky coal is the predominant fuel contained high concentrations of small particles with high organic content; organic extracts of these samples were mutagenic. Samples from homes in the wood-burning commune, which has a low rate of lung cancer, consisted mostly of larger particles of lower organic content and mutagenicity. The smoky coal sample was a mouse skin carcinogen and was a more potent initiator of skin tumors in comparison to the wood or smokeless coal sample.

  11. THE ROLE OF AQUEOUS THIN FILM EVAPORATIVE COOLING ON RATES OF ELEMENTAL MERCURY AIR-WATER EXCHANGE UNDER TEMPERATURE DISEQUILIBRIUM CONDITIONS

    EPA Science Inventory

    The technical conununity has only recently addressed the role of atmospheric temperature variations on rates of air-water vapor phase toxicant exchange. The technical literature has documented that: 1) day time rates of elemental mercury vapor phase air-water exchange can exceed ...

  12. Zero leakage separable and semipermanent ducting joints

    NASA Technical Reports Server (NTRS)

    Mischel, H. T.

    1973-01-01

    A study program has been conducted to explore new methods of achieving zero leakage, separable and semipermanent, ducting joints for space flight vehicles. The study consisted of a search of literature of existing zero leakage methods, the generation of concepts of new methods of achieving the desired zero leakage criteria and the development of detailed analysis and design of a selected concept. Other techniques of leak detection were explored with a view toward improving this area.

  13. Cave air and hydrological controls on prior calcite precipitation and stalagmite growth rates: Implications for palaeoclimate reconstructions using speleothems

    NASA Astrophysics Data System (ADS)

    Sherwin, Catherine M.; Baldini, James U. L.

    2011-07-01

    Hourly resolved cave air P and cave drip water hydrochemical data illustrate that calcite deposition on stalagmites can be modulated by prior calcite precipitation (PCP) on extremely short timescales. A very clear second-order covariation between cave air P and drip water Ca 2+ concentrations during the winter months demonstrates the effects of degassing-induced PCP on drip water chemistry. Estimating the strength of the cave air P control on PCP is possible because the PCP signal is so clear; at our drip site a one ppm shift in Ca 2+ concentrations requires a P shift of between 333 and 667 ppm. This value will undoubtedly vary from site to site, depending on drip water flow rate, residence time, drip water-cave air P differential, and availability of low P void spaces in the vadose zone above the cave. High-resolution cave environmental measurements were used to model calcite deposition on one stalagmite in Crag Cave, SW Ireland, and modelled growth over the study period (222 μm over 171 days) is extremely similar to the amount of actual calcite growth (240 μm) over the same time interval, strongly suggesting that equations used to estimate stalagmite growth rates are valid. Although cave air P appears to control drip water hydrochemistry in the winter, drip water dilution caused by rain events may have played a larger role during the summer, as evidenced by a series of sudden drops in Ca 2+ concentrations (dilution) followed by much more gradual increases in drip water Ca 2+ concentrations (slow addition of diffuse water). This research demonstrates that PCP on stalactites, cave ceilings, and void spaces within the karst above the cave partially controls drip water chemistry, and that thorough characterisation of this process at individual caves is necessary to most accurately interpret climate records from those sites.

  14. Leakage-current properties of encapsulants

    NASA Technical Reports Server (NTRS)

    Wen, L. C.

    1986-01-01

    A theoretical modeling of leakage current in ethylene vinyl acetate (EVA) and polyvinyl butyral (PVB) modules is being developed and is described. The modeling effort derives mathematical relationships for the bulk and surface conductivites of EVA and PVB, the surface conductivities of glass and polymeric films, and the EVA and PVB pottants, all as functions of environmental parameters. Results from the modeling indicate that for glass/EVA, the glass surface controls the interfacial conductivity, although EVA bulk conductivity controls total leakage current. For PVB/glass, the interface conductivity controls leakage currents for relative humidity (RH) less than 40 to 50%, but PVB bulk conductivity controls leakage current above 50% RH.

  15. Reduce Air Infiltration in Furnaces (English/Chinese) (Fact Sheet)

    SciTech Connect

    Not Available

    2011-10-01

    Chinese translation of the Reduce Air Infiltration in Furnaces fact sheet. Provides suggestions on how to improve furnace energy efficiency. Fuel-fired furnaces discharge combustion products through a stack or a chimney. Hot furnace gases are less dense and more buoyant than ambient air, so they rise, creating a differential pressure between the top and the bottom of the furnace. This differential, known as thermal head, is the source of a natural draft or negative pressure in furnaces and boilers. A well-designed furnace (or boiler) is built to avoid air leakage into the furnace or leakage of flue gases from the furnace to the ambient. However, with time, most furnaces develop cracks or openings around doors, joints, and hearth seals. These openings (leaks) usually appear small compared with the overall dimensions of the furnace, so they are often ignored. The negative pressure created by the natural draft (or use of an induced-draft fan) in a furnace draws cold air through the openings (leaks) and into the furnace. The cold air becomes heated to the furnace exhaust gas temperature and then exits through the flue system, wasting valuable fuel. It might also cause excessive oxidation of metals or other materials in the furnaces. The heat loss due to cold air leakage resulting from the natural draft can be estimated if you know four major parameters: (1) The furnace or flue gas temperature; (2) The vertical distance H between the opening (leak) and the point where the exhaust gases leave the furnace and its flue system (if the leak is along a vertical surface, H will be an average value); (3) The area of the leak, in square inches; and (4) The amount of operating time the furnace spends at negative pressure. Secondary parameters that affect the amount of air leakage include these: (1) The furnace firing rate; (2) The flue gas velocity through the stack or the stack cross-section area; (3) The burner operating conditions (e.g., excess air, combustion air temperature

  16. The Analysis of Ratings Using Generalizability Theory for Student Outcome Assessment. AIR 1988 Annual Forum Paper.

    ERIC Educational Resources Information Center

    Erwin, T. Dary

    Rating scales are a typical method for evaluating a student's performance in outcomes assessment. The analysis of the quality of information from rating scales poses special measurement problems when researchers work with faculty in their development. Generalizability measurement theory offers a set of techniques for estimating errors or…

  17. Identifying Peer Institutions for Graduation Rate Comparisons. AIR 2000 Annual Forum Paper.

    ERIC Educational Resources Information Center

    Walsh, Timothy A.

    This study used publicly available information to identify institutional controllable variables that influence graduation rate and to group colleges using these factors. The dependent variable for the correlation analysis was the six-year graduation rate of the fall 1993 freshman cohort (as reported by US News and World Report) at more than 1,400…

  18. Thermal image analysis for detecting facemask leakage

    NASA Astrophysics Data System (ADS)

    Dowdall, Jonathan B.; Pavlidis, Ioannis T.; Levine, James

    2005-03-01

    Due to the modern advent of near ubiquitous accessibility to rapid international transportation the epidemiologic trends of highly communicable diseases can be devastating. With the recent emergence of diseases matching this pattern, such as Severe Acute Respiratory Syndrome (SARS), an area of overt concern has been the transmission of infection through respiratory droplets. Approved facemasks are typically effective physical barriers for preventing the spread of viruses through droplets, but breaches in a mask"s integrity can lead to an elevated risk of exposure and subsequent infection. Quality control mechanisms in place during the manufacturing process insure that masks are defect free when leaving the factory, but there remains little to detect damage caused by transportation or during usage. A system that could monitor masks in real-time while they were in use would facilitate a more secure environment for treatment and screening. To fulfill this necessity, we have devised a touchless method to detect mask breaches in real-time by utilizing the emissive properties of the mask in the thermal infrared spectrum. Specifically, we use a specialized thermal imaging system to detect minute air leakage in masks based on the principles of heat transfer and thermodynamics. The advantage of this passive modality is that thermal imaging does not require contact with the subject and can provide instant visualization and analysis. These capabilities can prove invaluable for protecting personnel in scenarios with elevated levels of transmission risk such as hospital clinics, border check points, and airports.

  19. Simulating and explaining passive air sampling rates for semi-volatile compounds on polyurethane foam passive samplers

    PubMed Central

    Petrich, Nicholas T.; Spak, Scott N.; Carmichael, Gregory R.; Hu, Dingfei; Martinez, Andres; Hornbuckle, Keri C.

    2013-01-01

    Passive air samplers (PAS) including polyurethane foam (PUF) are widely deployed as an inexpensive and practical way to sample semi-volatile pollutants. However, concentration estimates from PAS rely on constant empirical mass transfer rates, which add unquantified uncertainties to concentrations. Here we present a method for modeling hourly sampling rates for semi-volatile compounds from hourly meteorology using first-principle chemistry, physics, and fluid dynamics, calibrated from depuration experiments. This approach quantifies and explains observed effects of meteorology on variability in compound-specific sampling rates and analyte concentrations; simulates nonlinear PUF uptake; and recovers synthetic hourly concentrations at a reference temperature. Sampling rates are evaluated for polychlorinated biphenyl congeners at a network of Harner model samplers in Chicago, Illinois during 2008, finding simulated average sampling rates within analytical uncertainty of those determined from loss of depuration compounds, and confirming quasi-linear uptake. Results indicate hourly, daily and interannual variability in sampling rates, sensitivity to temporal resolution in meteorology, and predictable volatility-based relationships between congeners. We quantify importance of each simulated process to sampling rates and mass transfer and assess uncertainty contributed by advection, molecular diffusion, volatilization, and flow regime within the PAS, finding PAS chamber temperature contributes the greatest variability to total process uncertainty (7.3%). PMID:23837599

  20. Dose rate estimates from irradiated light-water-reactor fuel assemblies in air

    SciTech Connect

    Lloyd, W.R.; Sheaffer, M.K.; Sutcliffe, W.G.

    1994-01-31

    It is generally considered that irradiated spent fuel is so radioactive (self-protecting) that it can only be moved and processed with specialized equipment and facilities. However, a small, possibly subnational, group acting in secret with no concern for the environment (other than the reduction of signatures) and willing to incur substantial but not lethal radiation doses, could obtain plutonium by stealing and processing irradiated spent fuel that has cooled for several years. In this paper, we estimate the dose rate at various distances and directions from typical pressurized-water reactor (PWR) and boiling-water reactor (BWR) spent-fuel assemblies as a function of cooling time. Our results show that the dose rate is reduced rapidly for the first ten years after exposure in the reactor, and that it is reduced by a factor of {approx}10 (from the one year dose rate) after 15 years. Even for fuel that has cooled for 15 years, a lethal dose (LD50) of 450 rem would be received at 1 m from the center of the fuel assembly after several minutes. However, moving from 1 to 5 m reduces the dose rate by over a factor of 10, and moving from 1 to 10 m reduces the dose rate by about a factor of 50. The dose rates 1 m from the top or bottom of the assembly are considerably less (about 10 and 22%, respectively) than 1 m from the center of the assembly, which is the direction of the maximum dose rate.

  1. Crash Rates of Scheduled Commuter and Air Carrier Flights Before and After a Regulatory Change

    PubMed Central

    Baker, Susan P.; Groff, Loren; Haaland, Wren; Qiang, Yandong; Rebok, George W.; Li, Guohua

    2010-01-01

    Introduction In 1997, in an effort to reduce the crash rate of scheduled commuter flights, the FAA required aircraft with 10–30 passenger seats to operate under stricter rules. Training and other requirements of 14 CFR Part 121 rules were applied to these midsize commuters, which previously had operated under the less strict Part 135 rules. Published crash rates obscured changes related to aircraft size. This research was undertaken to determine whether the rule change affected crash rates of aircraft with 10–30 passenger seats. Method We determined the number of passenger seats on each Part 135 or Part 121 aircraft that crashed between 1983 and 2007. For aircraft with < 10, 10–30, and > 30 seats, we estimated the numbers of departures and crash rates, adjusting for changes in total departures and numbers of in-service aircraft. Results The Part 135 crash rate tripled in 1997 when commuters with 10–30 seats were excluded, reflecting the administrative change. However, the crash rate of aircraft with 10–30 passenger seats began to decline 4 yr before the rule change; thereafter, their rate was lower than for larger aircraft. The fleet size of aircraft with 10–30 passenger seats increased from 1983 to 1997, then declined as they were replaced with larger aircraft in response to the rule change. Discussion No effect of the rule change on crash rates of 10–30-seat aircraft was apparent. The decline in their crash rates began before the rule change and may have been related to the 1992 requirement for ground proximity warning devices. PMID:19378909

  2. Oxidation rate of nuclear-grade graphite IG-110 in the kinetic regime for VHTR air ingress accident scenarios

    NASA Astrophysics Data System (ADS)

    Lee, Jo Jo; Ghosh, Tushar K.; Loyalka, Sudarshan K.

    2014-03-01

    The oxidation rates of nuclear-grade graphite IG-110 in the kinetically-controlled temperature regime of graphite oxidation were predicted and compared in Very High Temperature Reactor air ingress accident scenarios. The oxidative mass loss of graphite was measured thermogravimetrically from 873 to 1873 K in 100% air (21 mol%). The activation energy was found to be 222.07 kJ/mol, and the order of reaction with respect to oxygen concentration is 0.76. The surfaces of the samples were characterized by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Fourier Transform Infrared Spectroscopy and X-ray Photoelectron Spectroscopy before and after oxidation. These results are compared with those available in the literature, and our recently reported results for NBG-18 nuclear-grade graphite using the same technique.

  3. Cooling rates of living and killed chicken and quail eggs in air and in helium-oxygen gas mixture.

    PubMed

    Tazawa, H; Turner, J S; Paganelli, C V

    1988-01-01

    1. In a helium atmosphere, heat is dissipated from a surface 3.5 times faster than it is in air. Eggs in a helium-oxygen atmosphere cool only 1.4 times faster than they cool in air. This signifies that internal resistance to heat flow is a significant factor in the cooling rates of eggs. 2. Heat flow occurs inside an egg in two ways: by conduction through the tissues and in flowing blood. Killing an embryo stops the latter, but not the former. Eggs cool more slowly after they have been killed, signifying that blood flow can be an important component in an egg's internal flows of heat. 3. Blood flow should be a relatively more important component of heat flow in large eggs than in small eggs. The difference in conductance between living and killed eggs is larger in 60 g chicken eggs than it is in 10 g quail eggs. PMID:2900113

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

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

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

  5. Embedded computer controlled premixing inline injection system for air-assisted variable-rate sprayers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improvements to reduce chemical waste and environmental pollution for variable-rate sprayers used in orchards and ornamental nurseries require inline injection techniques. A microprocessor controlled premixing inline injection system implementing a ceramic piston chemical metering pump and two small...

  6. 16 CFR 1507.5 - Pyrotechnic leakage.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Pyrotechnic leakage. 1507.5 Section 1507.5 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES § 1507.5 Pyrotechnic leakage. The pyrotechnic chamber in fireworks devices shall be...

  7. 16 CFR 1507.5 - Pyrotechnic leakage.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Pyrotechnic leakage. 1507.5 Section 1507.5 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES § 1507.5 Pyrotechnic leakage. The pyrotechnic chamber in fireworks devices shall be...

  8. 16 CFR 1507.5 - Pyrotechnic leakage.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Pyrotechnic leakage. 1507.5 Section 1507.5 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES § 1507.5 Pyrotechnic leakage. The pyrotechnic chamber in fireworks devices shall be...

  9. 16 CFR 1507.5 - Pyrotechnic leakage.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Pyrotechnic leakage. 1507.5 Section 1507.5 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES § 1507.5 Pyrotechnic leakage. The pyrotechnic chamber in fireworks devices shall be...

  10. 16 CFR 1507.5 - Pyrotechnic leakage.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Pyrotechnic leakage. 1507.5 Section 1507.5 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES § 1507.5 Pyrotechnic leakage. The pyrotechnic chamber in fireworks devices shall be...

  11. 49 CFR 236.735 - Current, leakage.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Current, leakage. 236.735 Section 236.735 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Current, leakage. A stray electric current of relatively small value which flows through or across...

  12. 49 CFR 236.735 - Current, leakage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Current, leakage. 236.735 Section 236.735 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Current, leakage. A stray electric current of relatively small value which flows through or across...

  13. 49 CFR 236.735 - Current, leakage.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Current, leakage. 236.735 Section 236.735 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Current, leakage. A stray electric current of relatively small value which flows through or across...

  14. 49 CFR 236.735 - Current, leakage.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Current, leakage. 236.735 Section 236.735 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Current, leakage. A stray electric current of relatively small value which flows through or across...

  15. 49 CFR 236.735 - Current, leakage.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Current, leakage. 236.735 Section 236.735 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Current, leakage. A stray electric current of relatively small value which flows through or across...

  16. Bag Test Measures Leakage From Insulated Pipe

    NASA Technical Reports Server (NTRS)

    Schock, Kent D.; Easter, Barry P.

    1994-01-01

    Test quantifies leakage of gas from pipe even though pipe covered with insulation. Involves use of helium analyzer to measure concentration of helium in impermeable bag around pipe. Test administered after standard soap-solution bubble test indicates presence and general class of leakage.

  17. 49 CFR 230.78 - Leakage.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Brake and Signal Equipment § 230.78 Leakage. (a) Main reservoirs and related piping. Leakage from main reservoir and related piping shall be tested at every 92 service day inspection and shall not exceed an...

  18. 49 CFR 230.78 - Leakage.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Brake and Signal Equipment § 230.78 Leakage. (a) Main reservoirs and related piping. Leakage from main reservoir and related piping shall be tested at every 92 service day inspection and shall not exceed an...

  19. Relationships between ozone photolysis rates and peroxy radical concentrations in clean marine air over the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Penkett, S. A.; Monks, P. S.; Carpenter, L. J.; Clemitshaw, K. C.; Ayers, G. P.; Gillett, R. W.; Galbally, I. E.; Meyer, C. P.

    1997-06-01

    Measurements of the sum of inorganic and organic peroxy radicals (RO2) and photolysis rate coefficients J(NO2) and J(O1D) have been made at Cape Grim, Tasmania in the course of a comprehensive experiment which studied photochemistry in the unpolluted marine boundary layer. The SOAPEX (Southern Ocean Atmospheric Photochemistry Experiment) campaign included measurements of ozone, peroxides, nitrogen oxides, water vapor, and many other parameters. This first full length paper concerned with the experiment focuses on the types of relationships observed between peroxy radicals and J(NO2), J(O1D) and √[J(O1D)] in different air masses in which ozone is either produced or destroyed by photochemistry. It was found that in baseline air with ozone loss, RO2 was proportional to √[J(O1D)], whereas in more polluted air RO2 was proportional to J(O1D). Simple algorithms were derived to explain these relationships and also to calculate the concentrations of OH radicals in baseline air from the instantaneous RO2 concentrations. The signal to noise ratio of the peroxy radical measurements was up to 10 for 1-min values and much higher than in other previous deployments of the instrument in the northern hemisphere, leading to the confident determination of the relationships between RO2 and J(O1D) in different conditions. The absolute concentration Of RO2 determined in these experiments is in some doubt, but this does not affect our conclusions concerned either with the behavior of peroxy radicals with changing light levels or with the concentrations of OH calculated from RO2. The results provide confidence that the level of understanding of the photochemistry of ozone leading to the production of peroxide via recombination of peroxy radicals in clean air environments is well advanced.

  20. A two-dimensional simulation of plasma leakage due to dengue infection

    NASA Astrophysics Data System (ADS)

    Nuraini, N.; Windarto, Jayanti, Swarna; Soewono, Edy

    2014-03-01

    Dengue Hemorrhagic Fever (DHF) is a disease caused by Dengue virus infection. One major characteristic in a patient with DHF is the occurrence of plasma leakage. Plasma leakage is a consequence of the immune system mechanism which activates cytokine. As a result, permeability of vascular will increase. Another characteristic in a DHF patient is hypoalbuminea (decreasing of albumin concentration). Plasma leakage can be modelled by constructing mathematical model of albumin concentration in plasma blood due to increasing of cytokine. In this paper, decreasing of albumin concentration in blood plasma is modelled using diffusion equation. In addition, two-dimensional numerical simulations of albumin concentration are also presented. From the simulation, it is found that the greater leakage rate or the wider leakage area, the greater decreasing albumin concentration will be. Furthermore, when time t increases, the albumin concentration decreases to zero.

  1. Effects of Bulk Microdefects and Metallic Impurities on p-n Junction Leakage Currents in Silicon

    NASA Astrophysics Data System (ADS)

    Kim, Kwang-Salk; Moon, Byeong-sam; Kang, Hee-Bok; Park, Jea-gun; Lee, Bo-Young

    2010-03-01

    The effects of bulk microdefects and metallic impurities on leakage currents at p-n junctions have been evaluated quantitatively by relating leakage currents with bulk defects and metallic impurities, and the results are reported. Bulk defects and metallic impurities, which were introduced by appropriate thermal treatment and intentional contamination by spin-coating metal ion solutions onto the silicon surfaces, were shown to induce heavy leakage currents at p-n junctions, which had been manufactured by boron implantation and phosphorus diffusion. We found the bulk microdefects to be critical in causing leakage currents to flow and propose that their measurements be used as a means for the determination of the bulk defect densities. Die failure rates were also used for the evaluation of the effects of metallic impurities such as Cu, Ni, and Fe on the leakage currents.

  2. Leakage Currents and Gas Generation in Advanced Wet Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2015-01-01

    Currently, military grade, established reliability wet tantalum capacitors are among the most reliable parts used for space applications. This has been achieved over the years by extensive testing and improvements in design and materials. However, a rapid insertion of new types of advanced, high volumetric efficiency capacitors in space systems without proper testing and analysis of degradation mechanisms might increase risks of failures. The specifics of leakage currents in wet electrolytic capacitors is that the conduction process is associated with electrolysis of electrolyte and gas generation resulting in building up of internal gas pressure in the parts. The risk associated with excessive leakage currents and increased pressure is greater for high value advanced wet tantalum capacitors, but it has not been properly evaluated yet. In this work, in Part I, leakages currents in various types of tantalum capacitors have been analyzed in a wide range of voltages, temperatures, and time under bias. Gas generation and the level of internal pressure have been calculated in Part II for different case sizes and different hermeticity leak rates to assess maximal allowable leakage currents. Effects related to electrolyte penetration to the glass seal area have been studied and the possibility of failures analyzed in Part III. Recommendations for screening and qualification to reduce risks of failures have been suggested.

  3. The Gas Leakage Analysis in C/C Composites

    NASA Astrophysics Data System (ADS)

    Nishiyama, Yuichi; Hatta, Hiroshi; Bando, Takamasa; Sugibayashi, Toshio

    Gas leakage through carbon fiber reinforcement carbon composites, C/Cs, was discussed so as to apply C/Cs to heat exchangers in an engine system for a future space-plane. Since C/Cs include many cracks and pores, gas easily leaks through C/Cs. To predict and to prevent the gas flow through a C/C, leakage rate was measured as a function of pressure and gas flow path was identified by micro-observation of the C/C. Then, several analytical models were examined to clarify principal mechanism yielding gas flow resistance. It was found that laminar flow models gave far small flow resistance compared with experimental results, but a model based on adiabatic expansion and compression flow, used for gas leak through labyrinth seals, resulted in reasonable agreement. Finally, Si impregnation in a C/C was examined to minimize the gas leakage. This treatment was shown to be an excellent measure to reduce the gas leakage through C/C.

  4. The effects of air temperature on office workers' well-being, workload and productivity-evaluated with subjective ratings.

    PubMed

    Lan, Li; Lian, Zhiwei; Pan, Li

    2010-12-01

    Productivity bears a close relationship to the indoor environmental quality (IEQ), but how to evaluate office worker's productivity remains to be a challenge for ergonomists. In this study, the effect of indoor air temperature (17 °C, 21 °C, and 28 °C) on productivity was investigated with 21 volunteered participants in the laboratory experiment. Participants performed computerized neurobehavioral tests during exposure in the lab; their physiological parameters including heart rate variation (HRV) and electroencephalograph (EEG) were also measured. Several subjective rating scales were used to tap participant's emotion, well-being, motivation and the workload imposed by tasks. It was found that the warm discomfort negatively affected participants' well-being and increased the ratio of low frequency (LF) to high frequency (HF) of HRV. In the moderately uncomfortable environment, the workload imposed by tasks increased and participants had to exert more effort to maintain their performance and they also had lower motivation to do work. The results indicate that thermal discomfort caused by high or low air temperature had negative influence on office workers' productivity and the subjective rating scales were useful supplements of neurobehavioral performance measures when evaluating the effects of IEQ on productivity. PMID:20478555

  5. Microalgae cultivation in air-lift reactors: modeling biomass yield and growth rate as a function of mixing frequency.

    PubMed

    Barbosa, Maria J; Janssen, Marcel; Ham, Nienke; Tramper, Johannes; Wijffels, René H

    2003-04-20

    The slow development of microalgal biotechnology stems from the failure in the design of large-scale photobioreactors where light energy is efficiently utilized. Due to the light gradient inside the reactor and depending on the mixing properties, algae are subjected to certain light/dark cycles where the light period is characterized by a light gradient. These light/dark cycles will determine productivity and biomass yield on light energy. Air-lift reactors can be used for microalgae cultivation and medium-frequency light/dark cycles will be found in these systems. Light/dark cycles are associated with two basic parameters: first, the light fraction, i.e., the ratio between the light period and the cycle time and second, the frequency of the light/dark cycle. In the present work, light/dark cycles found in air-lift reactors were simulated taking into account the light gradient during the light period. The effect of medium-frequency cycle time (10-100 s) and light fraction (0.1-1) on growth rate and biomass yield on light energy of the microalgae Dunaliella tertiolecta was studied. The biomass yield and growth rates were mainly affected by the light fraction, while cycle time had little influence. Response surface methodology was used and a statistical model describing the effect of light fraction and cycle time on growth rate and biomass yield on light energy was developed. The use of the model as a reactor design criterion is discussed. PMID:12584758

  6. An accurate derivation of the air dose-rate and the deposition concentration distribution by aerial monitoring in a low level contaminated area

    NASA Astrophysics Data System (ADS)

    Nishizawa, Yukiyasu; Sugita, Takeshi; Sanada, Yukihisa; Torii, Tatsuo

    2015-04-01

    Since 2011, MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan) have been conducting aerial monitoring to investigate the distribution of radioactive cesium dispersed into the atmosphere after the accident at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), Tokyo Electric Power Company. Distribution maps of the air dose-rate at 1 m above the ground and the radioactive cesium deposition concentration on the ground are prepared using spectrum obtained by aerial monitoring. The radioactive cesium deposition is derived from its dose rate, which is calculated by excluding the dose rate of the background radiation due to natural radionuclides from the air dose-rate at 1 m above the ground. The first step of the current method of calculating the dose rate due to natural radionuclides is calculate the ratio of the total count rate of areas where no radioactive cesium is detected and the count rate of regions with energy levels of 1,400 keV or higher (BG-Index). Next, calculate the air dose rate of radioactive cesium by multiplying the BG-Index and the integrated count rate of 1,400 keV or higher for the area where the radioactive cesium is distributed. In high dose-rate areas, however, the count rate of the 1,365-keV peak of Cs-134, though small, is included in the integrated count rate of 1,400 keV or higher, which could cause an overestimation of the air dose rate of natural radionuclides. We developed a method for accurately evaluating the distribution maps of natural air dose-rate by excluding the effect of radioactive cesium, even in contaminated areas, and obtained the accurate air dose-rate map attributed the radioactive cesium deposition on the ground. Furthermore, the natural dose-rate distribution throughout Japan has been obtained by this method.

  7. Preoperative Nutritional Therapy Reduces the Risk of Anastomotic Leakage in Patients with Crohn's Disease Requiring Resections

    PubMed Central

    Guo, Zhen; Guo, Dong; Gong, Jianfeng; Zhu, Weiming; Zuo, Lugen; Sun, Jing; Li, Ning; Li, Jieshou

    2016-01-01

    Background. The rate of anastomotic leakage is high in surgeries for Crohn's disease, and therefore a temporary diverting stoma is often needed. We conducted this study to investigate whether preoperative nutritional therapy could reduce the risk of anastomotic leakage while decreasing the frequency of temporary stoma formation. Methods. This was a retrospective study. Patients requiring bowel resections due to Crohn's disease were reviewed. The rate of anastomotic leakage and temporary diverting stoma was compared between patients who received preoperative nutritional therapy and those on a normal diet before surgery. Possible predictive factors for anastomotic leakage were also analyzed. Results. One hundred and fourteen patients undergoing 123 surgeries were included. Patients in nutritional therapy (NT) group had a significantly lower level of C-reactive protein on the day before surgery. Patients in NT group suffered less anastomotic leakage (2.3% versus 17.9%, P = 0.023) and less temporary diverting stoma (22.8% versus 40.9%, P = 0.036). Serum albumin of the day before surgery ≤35 g/L and preoperative nutritional therapy were identified as factors which independently affected the rate of anastomotic leakage. Conclusion. Preoperative nutritional therapy reduced the risk of anastomotic leakage and the frequency of temporary diverting stoma formation in patients with Crohn's disease requiring resections. PMID:26858749

  8. Oxidation rate of graphitic matrix material in the kinetic regime for VHTR air ingress accident scenarios

    NASA Astrophysics Data System (ADS)

    Lee, Jo Jo; Ghosh, Tushar K.; Loyalka, Sudarshan K.

    2014-08-01

    Data on oxidation rates of matrix-grade graphite in the kinetically-controlled temperature regime of graphite oxidation are needed for safety analysis of High Temperature Gas Cooled Reactors and Very High Temperature Reactors. In this work, the oxidation rate of graphitic matrix material GKrS was measured thermogravimetrically for various oxygen concentrations and with temperatures from 873 to 1873 K. A semi-empirical Arrhenius rate equation was also developed for this temperature range. The activation energy of the graphitic material is found to be about 111.5 kJ/mol. The order of reaction was found to be about 0.89. The surface of oxidized GKrS was characterized by Scanning Electron Microscopy, Electron Dispersive Spectroscopy, Fourier Transform Infrared Spectroscopy and X-ray Photoelectron Spectroscopy.

  9. Safety in the Chemical Laboratory: Laboratory Air Quality: Part II. Measurements of Ventilation Rates.

    ERIC Educational Resources Information Center

    Butcher, Samuel S.; And Others

    1985-01-01

    Part I of this paper (SE 538 295) described a simple model for estimating laboratory concentrations of gas phase pollutants. In this part, the measurement of ventilation rates and applications of the model are discussed. The model can provide a useful starting point in planning for safer instructional laboratories. (JN)

  10. Real time monitoring of petroleum leakage detection using etched fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Shivananju, B. N.; Kiran, M.; Nithin, S. P.; Vidya, M. J.; Hegde, G. M.; Asokan, S.

    2013-06-01

    Detection of petroleum leakages in pipelines and storage tanks is a very important as it may lead to significant pollution of the environment, accidental hazards, and also it is a very important fuel resource. Petroleum leakage detection sensor based on fiber optics was fabricated by etching the fiber Bragg grating (FBG) to a region where the total internal reflection is affected. The experiment shows that the reflected Bragg's wavelength and intensity goes to zero when etched FBG is in air and recovers Bragg's wavelength and intensity when it is comes in contact with petroleum or any external fluid. This acts as high sensitive, fast response fluid optical switch in liquid level sensing, petroleum leakage detection etc. In this paper we present our results on using this technique in petroleum leakage detection.

  11. Coupling of MASH-MORSE Adjoint Leakages with Space- and Time-Dependent Plume Radiation Sources

    SciTech Connect

    Slater, C.O.

    2001-04-20

    In the past, forward-adjoint coupling procedures in air-over-ground geometry have typically involved forward fluences arising from a point source a great distance from a target or vehicle system. Various processing codes were used to create localized forward fluence files that could be used to couple with the MASH-MORSE adjoint leakages. In recent years, radiation plumes that result from reactor accidents or similar incidents have been modeled by others, and the source space and energy distributions as a function of time have been calculated. Additionally, with the point kernel method, they were able to calculate in relatively quick fashion free-field radiation doses for targets moving within the fluence field or for stationary targets within the field, the time dependence for the latter case coming from the changes in position, shape, source strength, and spectra of the plume with time. The work described herein applies the plume source to the MASH-MORSE coupling procedure. The plume source replaces the point source for generating the forward fluences that are folded with MASH-MORSE adjoint leakages. Two types of source calculations are described. The first is a ''rigorous'' calculation using the TORT code and a spatially large air-over-ground geometry. For each time step desired, directional fluences are calculated and are saved over a predetermined region that encompasses a structure within which it is desired to calculate dose rates. Processing codes then create the surface fluences (which may include contributions from radiation sources that deposit on the roof or plateout) that will be coupled with the MASH-MORSE adjoint leakages. Unlike the point kernel calculations of the free-field dose rates, the TORT calculations in practice include the effects of ground scatter on dose rates and directional fluences, although the effects may be underestimated or overestimated because of the use of necessarily coarse mesh and quadrature in order to reduce computational

  12. Numerical analysis of reaction-diffusion effects on species mixing rates in turbulent premixed methane-air combustion

    SciTech Connect

    Richardson, E.S.; Grout, R.W.; Chen, J.H.; Sankaran, R.

    2010-03-15

    The scalar mixing time scale, a key quantity in many turbulent combustion models, is investigated for reactive scalars in premixed combustion. Direct numerical simulations (DNS) of three-dimensional, turbulent Bunsen flames with reduced methane-air chemistry have been analyzed in the thin reaction zones regime. Previous conclusions from single step chemistry DNS studies are confirmed regarding the role of dilatation and turbulence-chemistry interactions on the progress variable dissipation rate. Compared to the progress variable, the mixing rates of intermediate species is found to be several times greater. The variation of species mixing rates are explained with reference to the structure of one-dimensional premixed laminar flames. According to this analysis, mixing rates are governed by the strong gradients which are imposed by flamelet structures at high Damkoehler numbers. This suggests a modeling approach to estimate the mixing rate of individual species which can be applied, for example, in transported probability density function simulations. Flame-turbulence interactions which modify the flamelet based representation are analyzed. (author)

  13. Corrosion product identification and relative rates of corrosion of candidate metals in an irradiated air-steam environment

    SciTech Connect

    Reed, D.T.; Swayambunathan, V.; Tani, B.S. ); Van Konynenburg, R.A. )

    1989-11-03

    Previously reported work by others indicates that dicopper trihydroxide nitrate, Cu{sub 2}NO{sub 3}(OH){sub 3}, forms on copper and copper alloys subjected to irradiated moist air near room temperature. We have performed experiments over a range of temperature and humidity, and have found that this species is formed at temperatures up to at least 150{degree}C if low to intermediate relative humidities are present. At 150{degree}C and 100% relative humidity, only Cu{sub 2}O and CuO were observed. The relative general corrosion rates of the copper materials tested in 1-month experiments at dose rates of 0.7 and 2.0 kGy/h were Cu > 70/30 Cu--Ni > Al-bronze. High-nickel alloy 825 showed no observable corrosion. 29 refs., 4 tabs.

  14. SENSOR FOR INDIVIDUAL BURNER CONTROL OF FIRING RATE, FUEL-AIR RATIO, AND COAL FINENESS CORRELATION

    SciTech Connect

    Wayne Hill; Roger Demler; Robert G. Mudry

    2004-10-01

    Instrumentation difficulties encountered in the previous reporting period were addressed early in this reporting period, resulting in a new instrumentation configuration that appears to be free of the noise issues found previously. This permitted the collection of flow calibration data to begin. The first issues in question are the effects of the type and location of the transducer mount. Data were collected for 15 different transducer positions (upstream and downstream of an elbow in the pipe), with both a stud mount and a magnetic transducer mount, for each of seven combinations of air and coal flow. Analysis of these data shows that the effects of the transducer mount type and location on the resulting dynamics are complicated, and not easily captured in a single analysis. To maximize the practical value of the calibration data, further detailed calibration data will be collected with both the magnetic and stud mounts, but at a single mounting location just downstream of a pipe elbow. This testing will be performed in the Coal Flow Test Facility in the next reporting period. The program progress in this reporting period was sufficient to put us essentially back on schedule.

  15. Influence of liquid and gas flow rates on sulfuric acid mist removal from air by packed bed tower

    PubMed Central

    2012-01-01

    The possible emission of sulfuric acid mists from a laboratory scale, counter-current packed bed tower operated with a caustic scrubbing solution was studied. Acid mists were applied through a local exhaust hood. The emissions from the packed bed tower were monitored in three different categories of gas flow rate as well as three liquid flow rates, while other influencing parameters were kept almost constant. Air sampling and sulfuric acid measurement were carried out iso-kinetically using USEPA method 8. The acid mists were measured by the barium-thorin titration method. According to the results when the gas flow rate increased from 10 L/s to 30 L/s, the average removal efficiency increased significantly (p < 0.001) from 76.8 ± 1.8% to 85.7 ± 1.2%. Analysis of covariance method followed by Tukey post-hoc test of 92 tests did not show a significant change in removal efficiency between liquid flow rates of 1.5, 2.5 and 3.5 L/min (p = 0.811). On the other hand, with fixed pressure loss across the tower, by increasing the liquid/gas (L/G) mass ratio, the average removal efficiency decreased significantly (p = 0.001) from 89.9% at L/G of <2 to 83.1% at L/G of 2–3 and further to 80.2% at L/G of >3, respectively. L/G of 2–3 was recommended for designing purposes of a packed tower for sulfuric acid mists and vapors removal from contaminated air stream. PMID:23369487

  16. Particulate Air Pollution and the Rate of Hospitalization for Congestive Heart Failure among Medicare Beneficiaries in Pittsburgh, Pennsylvania.

    PubMed Central

    Wellenius, Gregory A.; Bateson, Thomas F.; Mittleman, Murray A.; Schwartz., Joel

    2006-01-01

    We used a case-crossover approach to evaluate the association between ambient air pollution and the rate of hospitalization for congestive heart failure (CHF) among Medicare recipients (age ≥ 65) residing in Allegheny County (Pittsburgh area), PA, during 1987–1999. We also explored effect modification by age, gender, and specific secondary diagnoses. During follow-up, there were 55,019 admissions with a primary diagnosis of CHF. We found that particulate matter with aerodynamic diameter ≤ 10 μm (PM10), carbon monoxide (CO), nitrogen dioxide (NO2), and sulfur dioxide – but not ozone – were positively and significantly associated with the rate of admission on the same day in single-pollutant models. The strongest associations were observed with CO, NO2 and PM10. The associations with CO and NO2 were the most robust in two-pollutant models, remaining statistically significant even after adjusting for other pollutants. Patients with a recent myocardial infarction were at greater risk of particulate-related admission, but there was otherwise no significant effect modification by age, gender, or other secondary diagnoses. These results suggest that short-term elevations in air pollution from traffic-related sources may trigger acute cardiac decompensation of heart failure patients and that those with certain comorbid conditions may be more susceptible to these effects. PMID:15901623

  17. Properties of the seawater-air interface. 2. Rates of surface film formation under steady state conditions

    SciTech Connect

    Dragcevic, D.; Pravdic, V.

    1981-05-01

    The laboratory techniques of dynamic surface tension and of surface electrical potential measurements were used to determine rates of formation and of reorientation of organic surface films at the seawater-air interface. Relaxation times of surface films were determined for three characteristic samples obtained by screen and bottle sampling in the coastal waters of the northern Adriatic area. These data were compared with those for model samples produced by spreading oleic acid and crude oil on or dissolving polyethyleneglycol and sodium dodecyl sulfate in artificial seawater. Relaxation times were in the range of 0.1-1 s for most of the samples. A good representative value for field samples is 0.2 s. The temperature-dependence (the energies of activation) for the surface film relaxation indicates that several processes control material transport toward the seawater-air interface. The findings are interpreted as showing that an almost ever-present organic surface film influences the mechanism and the rate of material transport across the sea-atmosphere boundary.

  18. Air Change Rates and Interzonal Flows in Residences, and the Need for Multi-Zone Models for Exposure and Health Analysis

    EPA Science Inventory

    Air change rates (ACRs) and interzonal flows are key determinants of indoor air quality (IAQ) and building energy use. This paper characterizes ACRs and interzonal flows in 126 houses, and evaluates effects of these parameters on IAQ. ACRs measured using weeklong tracer measureme...

  19. Identifying Housing and Meteorological Conditions Influencing Residential Air Exchange Rates in the DEARS and RIOPA Studies: Development of Distributions for Human Exposure Modeling

    EPA Science Inventory

    Appropriate prediction of residential air exchange rate (AER) is important for estimating human exposures in the residential microenvironment, as AER drives the infiltration of outdoor-generated air pollutants indoors. AER differences among homes may result from a number of fact...

  20. Effect of ventilation systems and air filters on decay rates of particles produced by indoor sources in an occupied townhouse

    NASA Astrophysics Data System (ADS)

    Howard-Reed, Cynthia; Wallace, Lance A.; Emmerich, Steven J.

    Several studies have shown the importance of particle losses in real homes due to deposition and filtration; however, none have quantitatively shown the impact of using a central forced air fan and in-duct filter on particle loss rates. In an attempt to provide such data, we measured the deposition of particles ranging from 0.3 to 10 μm in an occupied townhouse and also in an unoccupied test house. Experiments were run with three different sources (cooking with a gas stove, citronella candle, pouring kitty litter), with the central heating and air conditioning (HAC) fan on or off, and with two different types of in-duct filters (electrostatic precipitator and ordinary furnace filter). Particle size, HAC fan operation, and the electrostatic precipitator had significant effects on particle loss rates. The standard furnace filter had no effect. Surprisingly, the type of source (combustion vs. mechanical generation) and the type of furnishings (fully furnished including carpet vs. largely unfurnished including mostly bare floor) also had no measurable effect on the deposition rates of particles of comparable size. With the HAC fan off, average deposition rates varied from 0.3 h -1 for the smallest particle range (0.3-0.5 μm) to 5.2 h -1 for particles greater than 10 μm. Operation of the central HAC fan approximately doubled these rates for particles <5 μm, and increased rates by 2 h -1 for the larger particles. An in-duct electrostatic precipitator increased the loss rates compared to the fan-off condition by factors of 5-10 for particles <2.5 μm, and by a factor of 3 for 2.5-5.0 μm particles. In practical terms, use of the central fan alone could reduce indoor particle concentrations by 25-50%, and use of an in-duct ESP could reduce particle concentrations by 55-85% compared to fan-off conditions.

  1. Development and Evaluation of a New Air Exchange Rate Algorithm for the Stochastic Human Exposure and Dose Simulation Model (ISES Presentation)

    EPA Science Inventory

    Previous exposure assessment panel studies have observed considerable seasonal, between-home and between-city variability in residential pollutant infiltration. This is likely a result of differences in home ventilation, or air exchange rates (AER). The Stochastic Human Exposure ...

  2. Improvement Accuracy of Assessment of Total Equivalent Dose Rate during Air Travel

    NASA Astrophysics Data System (ADS)

    Dorenskiy, Sergey; Minligareev, Vladimir

    For radiation safety on the classic flight altitudes 8-11 km is necessary to develop a methodology for calculating the total equivalent dose rate (EDR) to prevent excess exposure of passengers and crews of airliners. During development it became necessary to assess all components affecting the calculation of EDR Comprehensive analysis of the solution to this problem, based on the developed program basis, allowing to automate calculations , as well as on the assessment of the statistical data is introduced. The results have shown that: 1) Limiting accuracy of error of geomagnetic cutoff rigidity (GCR) in the period from 2005 to 2010 was 5% This error is not significant within the considered problems. 2) It is necessary to take into account seasonal variations of atmospheric parameters in the calculation of the EDR. The difference in the determination of dose rate can reach 31% Diurnal variations of atmospheric parameters are offered to consider to improve reliability of EDR estimates. 3) Introduction in the GCR calculations of additional parameters is necessary for reliability improvement and estimation accuracy of EDR on flight routs (Kp index of geomagnetic activity , etc.).

  3. SCC Propagation Rate of Type 304, 304L Steels Under Oceanic Air Environment

    SciTech Connect

    Akio Kosaki

    2006-07-01

    Corrosion integrity of canister in the concrete cask for spent fuel storage is very important because the canister serves to maintain the sealability over the storage period of 40 to 60 years. Natural exposure and accelerated corrosion tests of conventional stainless steels for canister, that are Type 304, 304L, and 316(LN), for concrete cask's canister have been conducted by using many three Point Bending (3PB) test specimens and compared. The SCC propagation rates in Type 304 and 304L at the natural condition were about 1.2 E-12 to 1.8 E-11 m/s at the K (Stress Intensity Factor) range of 0.6 to 9.0 MPa/m, and that of the accelerate test (60 degrees C, 95%RHS., filled with NaCl mist.) were about 1.0 E-10 to 3.5 E-9 m/s at the K range of 0.3 to 32 MPa/m. The SCC propagation rates under both natural and accelerated conditions were independent with K. Both da/dt values of the direct exposure test and of the under glass exposure test were in the same scattering band. (author)

  4. Human subject testing of leakage in a loose-fitting PAPR.

    PubMed

    Johnson, Arthur T; Koh, Frank C; Jamshidi, Shaya; Rehak, Timothy E

    2008-05-01

    Leakage from loose-fitting PAPRs (powered air-purifying respirators) can compromise the safety of wearers. The Martindale Centurion MAX multifunction PAPR is a loose-fitting PAPR that also incorporates head, eye, and ear protection. This respirator is used in mines where coal dust usually is controlled by ventilation systems. Should the respirator be depended on for significant respiratory protection? Ten human volunteers were asked to wear the Centurion MAX inside a fog-filled chamber. Their inhalation flow rates were measured with small pitot-tube flowmeters held inside their mouths. They were video imaged while they breathed deeply, and the points at which the fog reached their mouths were determined. Results showed that an average of 1.1 L could be inhaled before contaminated air reached the mouth. As long as the blower purges contamination from inside the face piece during exhalation, the 1.1 L acts as a buffer against contaminants leaked due to overbreathing of blower flow rate. PMID:18348078

  5. Human subject testing of leakage in a loose-fitting PAPR

    SciTech Connect

    Johnson, A.T.; Koh, F.C.; Jamshidi, S.; Rehak, T.E.

    2008-07-01

    Leakage from loose-fitting PAPRs (powered air-purifying respirators) can compromise the safety of wearers. The Martindale Centurion MAX multifunction PAPR is a loose-fitting PAPR that also incorporates head, eye, and ear protection. This respirator is used in mines where coal dust usually is controlled by ventilation systems. Should the respirator be depended on for significant respiratory protection? Ten human volunteers were asked to wear the Centurion MAX inside a fog-filled chamber. Their inhalation flow rates were measured with small pitot-tube flowmeters held inside their mouths. They were video imaged while they breathed deeply, and the points at which the fog reached their mouths were determined. Results showed that an average of 1.1 L could be inhaled before contaminated air reached the mouth. As long as the blower purges contamination from inside the face piece during exhalation, the 1.1 L acts as a buffer against contaminants leaked due to overbreathing of blower flow rate.

  6. Numerical and experimental evaluation of a new low-leakage labyrinth seal

    NASA Technical Reports Server (NTRS)

    Rhode, D. L.; Ko, S. H.; Morrison, G. L.

    1988-01-01

    The effectiveness of a recently developed leakage model for evaluating new design features of most seals is demonstrated. A preliminary assessment of the present stator groove feature shows that it gives approximately a 20 percent leakage reduction with no shaft speed effects. Also, detailed distributions of predicted streamlines, axial velocity, relative pressure and turbulence energy enhance one's physical insight. In addition, the interesting measured effect of axial position of the rotor/stator pair on leakage rate and stator wall axial pressure distribution is examined.

  7. Multigas Leakage Correction in Static Environmental Chambers Using Sulfur Hexafluoride and Raman Spectroscopy.

    PubMed

    Jochum, Tobias; von Fischer, Joseph C; Trumbore, Susan; Popp, Jürgen; Frosch, Torsten

    2015-11-01

    In static environmental chamber experiments, the precision of gas flux measurements can be significantly improved by a thorough gas leakage correction to avoid under- or overestimation of biological activity such as respiration or photosynthesis. Especially in the case of small biological net gas exchange rates or gas accumulation phases during long environmental monitoring experiments, gas leakage fluxes could distort the analysis of the biogenic gas kinetics. Here we propose and demonstrate a general protocol for online correction of diffusion-driven gas leakage in plant chambers by simultaneous quantification of the inert tracer sulfur hexafluoride (SF6) and the investigated biogenic gases using enhanced Raman spectroscopy. By quantifying the leakage rates of carbon dioxide (CO2), methane (CH4), and hydrogen (H2) simultaneously with SF6 in the test chamber, their effective diffusivity ratios of approximately 1.60, 1.96, and 5.65 were determined, each related to SF6. Because our experiments suggest that the effective diffusivity ratios are reproducible for an individual static environmental chamber, even under varying concentration gradients and slight changes of the chamber sealing, an experimental method to quantify gas leakage fluxes by using effective diffusivity ratios and SF6 leakage fluxes is proposed. The method is demonstrated by quantifying the CO2 net exchange rate of a plant-soil ecosystem (Mirabilis jalapa). By knowing the effective chamber diffusivity ratio CO2/SF6 and the measured SF6 leakage rate during the experiment, the leakage contribution to the total CO2 exchange rate could be calculated and the biological net CO2 concentration change within the chamber atmosphere determined. PMID:26492154

  8. A Novel Method for Quantifying the Inhaled Dose of Air Pollutants Based on Heart Rate, Breathing Rate and Forced Vital Capacity

    PubMed Central

    Greenwald, Roby; Hayat, Matthew J.; Barton, Jerusha; Lopukhin, Anastasia

    2016-01-01

    To better understand the interaction of physical activity and air pollution exposure, it is important to quantify the change in ventilation rate incurred by activity. In this paper, we describe a method for estimating ventilation using easily-measured variables such as heart rate (HR), breathing rate (fB), and forced vital capacity (FVC). We recruited healthy adolescents to use a treadmill while we continuously measured HR, fB, and the tidal volume (VT) of each breath. Participants began at rest then walked and ran at increasing speed until HR was 160–180 beats per minute followed by a cool down period. The novel feature of this method is that minute ventilation (V˙E) was normalized by FVC. We used general linear mixed models with a random effect for subject and identified nine potential predictor variables that influence either V˙E or FVC. We assessed predictive performance with a five-fold cross-validation procedure. We used a brute force selection process to identify the best performing models based on cross-validation percent error, the Akaike Information Criterion and the p-value of parameter estimates. We found a two-predictor model including HR and fB to have the best predictive performance (V˙E/FVC = -4.247+0.0595HR+0.226fB, mean percent error = 8.1±29%); however, given the ubiquity of HR measurements, a one-predictor model including HR may also be useful (V˙E/FVC = -3.859+0.101HR, mean percent error = 11.3±36%). PMID:26809066

  9. Gas exchange rates across the sediment-water and air-water interfaces in south San Francisco Bay

    USGS Publications Warehouse

    Hartman, Blayne; Hammond, Douglas E.

    1984-01-01

    Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainty of the determinations, about 20%. The annual average of benthic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water interface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2–6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models.

  10. Measurement of air dose rates over a wide area around the Fukushima Dai-ichi Nuclear Power Plant through a series of car-borne surveys.

    PubMed

    Andoh, Masaki; Nakahara, Yukio; Tsuda, Shuichi; Yoshida, Tadayoshi; Matsuda, Norihiro; Takahashi, Fumiaki; Mikami, Satoshi; Kinouchi, Nobuyuki; Sato, Tetsuro; Tanigaki, Minoru; Takamiya, Koichi; Sato, Nobuhiro; Okumura, Ryo; Uchihori, Yukio; Saito, Kimiaki

    2015-01-01

    A series of car-borne surveys using the Kyoto University RAdiation MApping (KURAMA) and KURAMA-II survey systems has been conducted over a wide area in eastern Japan since June 2011 to evaluate the distribution of air dose rates around the Fukushima Dai-ichi Nuclear Power Plant and to evaluate the time-dependent trend of decrease in air dose rates. An automated data processing system for the KURAMA-II system was established, which enabled rapid analysis of large amounts of data obtained using about 100 KURAMA-II units. The initial data used for evaluating the migration status of radioactive cesium were obtained in the first survey, followed by other car-borne surveys conducted over more extensive and wider measurement ranges. By comparing the measured air dose rates obtained in each survey (until December 2012), the decreasing trend of air dose rates measured through car-borne surveys was found to be more pronounced than those expected on the basis of the physical decay of radioactive cesium and of the air dose rates measured using NaI (Tl) survey meters in the areas surrounding the roadways. In addition, it was found that the extent of decrease in air dose rates depended on land use, wherein it decreased faster for land used as building sites than for forested areas. PMID:24951121

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

    MedlinePlus

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

  12. Composite seal reduces alkaline battery leakage

    NASA Technical Reports Server (NTRS)

    Clatterbuck, C. H.; Plitt, K. F.

    1965-01-01

    Composite seal consisting of rubber or plastic washers and a metal washer reduces alkaline battery leakage. Adhesive is applied to each washer interface, and the washers are held together mechanically.

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

    MedlinePlus

    ... news/fullstory_159116.html Early Alzheimer's Linked to Brain 'Leakage' Normally, blood-brain barrier prevents this from happening To use the ... more "leaks" in the barrier that separates the brain from the bloodstream, a small study suggests. Known ...

  14. Laboratory Performance Testing of Residential Window Air Conditioners

    SciTech Connect

    Winkler, J.; Booten, C.; Christensen, D.; Tomerlin, J.

    2013-03-01

    Window air conditioners are the dominant cooling product for residences, in terms of annual unit sales. They are inexpensive, portable and can be installed by the owner. For this reason, they are an attractive solution for supplemental cooling, for retrofitting air conditioning into a home which lacks ductwork, and for renters. Window air conditioners for sale in the United States are required to meet very modest minimum efficiency standards. Four window air conditioners' performance were tested in the Advanced HVAC Systems Laboratory on NREL's campus in Golden, CO. In order to separate and study the refrigerant system's performance, the unit's internal leakage pathways, the unit's fanforced ventilation, and the leakage around the unit resulting from installation in a window, a series of tests were devised that focused on each aspect of the unit's performance. These tests were designed to develop a detailed performance map to determine whole-house performance in different climates. Even though the test regimen deviated thoroughly from the industry-standard ratings test, the results permit simple calculation of an estimated rating for both capacity and efficiency that would result from a standard ratings test. Using this calculation method, it was found that the three new air conditioners' measured performance was consistent with their ratings. This method also permits calculation of equivalent SEER for the test articles. Performance datasets were developed across a broad range of indoor and outdoor operating conditions, and used them to generate performance maps.

  15. Leakage test concerns for packagings with three-O-ring closure seals

    SciTech Connect

    Oras, J.J.; Towell, R.H.; Wangler, M.E.

    1997-07-01

    Recent radioactive packagings with three-O-ring closure seals, the middle O-ring being the containment seal, have the potential for false positive results from leakage rate tests. The volume between the containment O-ring and the inner O-ring is used for the helium gas required for the leakage rate tests, to reduce both the amount of helium used and the time for the tests. False positive results can be caused by either a large leakage in the containment sea/l or a leakage in the inner seal. This paper describes the problem, together with possible solutions/areas that need to be addressed in a Safety Analysis Report for Packaging.

  16. Continued Investigation of Leakage and Power Loss Test Results for Competing Turbine Engine Seals

    NASA Technical Reports Server (NTRS)

    Delgado, Irebert R.; Proctor, Margaret P.

    2007-01-01

    Seal leakage decreases with increasing surface speed due to reduced clearances from disk centrifugal growth. Annular and labyrinth seal leakage are 2-3 times greater than brush and finger seal leakage. Seal leakage rates increase with increasing temperature because of seal clearance growth due to different coefficients of thermal expansion between the seal and test disk. Seal power loss is not strongly affected by inlet temperature. Seal power loss increases with increasing surface speed, seal pressure differential, mass flow rate or flow factor, and radial clearance. The brush and finger seals had nearly the same power loss. Annular and labyrinth seal power loss were higher than finger or brush seal power loss. The brush seal power loss was the lowest and 15-30% lower than annular and labyrinth seal power loss.

  17. Measuring Heat-Exchanger Water Leakage

    NASA Technical Reports Server (NTRS)

    Zampiceni, J.

    1986-01-01

    Water leakage in heat exchanger measured directly with help of electroytic hygrometer. In new technique, flow of nitrogen gas set up in one loop of heat exchanger. Other loop filled with water under pressure. Water concentration produced by leakage of water into nitrogen flow measured by hygrometer. New measurement method determines water concentrations up to 2,000 parts per million with accuracy of +/- 5 percent.

  18. Technology evaluation for space station atmospheric leakage

    SciTech Connect

    Lemon, D.K.; Friesel, M.A.; Griffin, J.W.; Skorpik, J.R.; Shepard, C.L.; Antoniak, Z.I.; Kurtz, R.J.

    1990-02-01

    A concern in operation of a space station is leakage of atmosphere through seal points and through the walls as a result of damage from particle (space debris and micrometeoroid) impacts. This report describes a concept for a monitoring system to detect atmosphere leakage and locate the leak point. The concept is based on analysis and testing of two basic methods selected from an initial technology survey of potential approaches. 18 refs., 58 figs., 5 tabs.

  19. SENSOR FOR INDIVIDUAL BURNER CONTROL OF FIRING RATE, FUEL-AIR RATIO, AND COAL FINENESS CORRELATION

    SciTech Connect

    Wayne Hill; Roger Demler; Robert G. Mudry

    2005-01-01

    Additional calibration data were collected in the Coal Flow Test Facility early in this reporting period. These data comprised a total of 181 tests for stud and magnetic accelerometer mounts, with two mounting locations relative to two different pipe elbows, and including some tests with out-of-plane elbows upstream of the test section to produce coal ''roping''. The results found in analyzing these new data were somewhat disappointing: correlations for coal flow rate for a given mount type and mounting location were less accurate than desired, and degraded badly when data from other locations were included in the same analysis. Reviewing all of the data files (from both the earlier testing and recent calibration testing) disclosed a significant fraction of cases with several forms of noise. Eliminating these cases improved the correlations somewhat, but the number of cases that remained did not permit general conclusions to be drawn. It was finally learned that yet another type of noise is present in some data files, producing a strong effect on the correlation accuracy. The cases not subject to this noise correlated very well. It would be desirable to collect additional data in the Coal Flow Test Facility prior to moving on to field data collection, a change in program direction that would require a no-cost time extension.

  20. Characteristic of flotation deinking using bio and synthetic surfactant at different air flow rate

    NASA Astrophysics Data System (ADS)

    Trismawati, Wardana, I. N. G.; Hamidi, Nurkholis; Sasongko, Mega Nur

    2016-03-01

    Flotation deinking has industrially applied but several problems keep unsolved because limitations have to compete with several variables present. Flotation deinking is multi variables process, so studying flotation deinking is still interesting. In this research, the amount of variables was reduced and focused to the performance comparison between flotation deinking of old newspaper (ONP) using biodegradable fatty acid of morinda citrifolia as the raw bio surfactant (RBS) and biodegradable fatty acid of palm oil that had been converted to be commercial surfactant (CS). The flotation was done at laboratory flotation cell equipped with orifice at different diameter (orifice number 20, 40 and 60) with adjustable airflow rate. Brightness and Effective Residual Ink Concentration (ERIC) of the deinked pulp were measured. The best results were achieved on orifice number 40 with the highest brightness of 41.96 °ISO and 40.96 °ISO when using CS and RBS respectively, and lowest ERIC of 896.82 ppm and 1001.72 ppm when using CS and RBS respectively. The percentage delta of deinking power characteristic between CS and RBS was 2.36% and 11.70% for brightness and ERIC, respectively.

  1. Leakage diagnostics, sealant longevity, sizing and technologytransfer in residential thermal distribution systems: Part II.Residential thermal Distribution Systesm, Phase VI FinalReport

    SciTech Connect

    Buchanan, C.; Modera, M.; Sherman, M.; Siegel, J.; Walker, I.; Wang, D.

    1998-12-01

    This report builds on and extends our previous efforts as described in "Leakage Diagnostics, Sealant Longevity, Sizing and Technology Transfer in Residential Thermal Distribution Systems- CIEE Residential Thermal Distribution Systems Phase V Final Report, October 1997". New developments include defining combined duct and equipment efficiencies in a concept called "Tons At the Register" and on performance issues related to field use of the aerosol sealant technology. Some of the key results discussed in this report include: o Register, boot and air handler cabinet leakage can often represent a significant fraction of the total duct leakage in new construction. Because of the large range of pressures in duct systems an accurate characterization may require separating these components through improved leakage testing. o Conventional duct tape failed our accelerated longevity testing and is not, therefore, considered generally acceptable for use in sealing duct systems. Many other tapes and sealing approaches are available and practical and have passed our longevity tests. o Simulations of summer temperature pull-down time have shown that duct system improvements can be combined with equipment downsizing to save first cost, energy consumption, and peak power and still provide equivalent or superior comfort. o Air conditioner name plate capacity ratings alone are a poor indicator of how much cooling will actually be delivered to the conditioned space. Duct system efficiency can have as large an impact on performance as variations in SEER. o Mechanical duct cleaning techniques do not have an adverse impact on the ducts sealed with the Aerosol sealant. The material typically used in Aerosol sealing techniques does not appear to present a health or safety hazard. Results from this study were used by the California Energy Commission in the formation of the current Energy Efficiency Standards for Low-Rise Residential Buildings (CEC, (1998)), often referred to as Title 24

  2. SENSOR FOR INDIVIDUAL BURNER CONTROL OF FIRING RATE, FUEL-AIR RATIO, AND COAL FINENESS CORRELATION

    SciTech Connect

    Wayne Hill

    2004-10-01

    The project's overall objective is to develop a commercially viable sensing system to infer the flow rate and fineness of pulverized coal flows using the dynamic signature from a pipe-mounted accelerometer. The preliminary calibration data for this effort will be obtained using a Coal Flow Test Facility built and operated by our subcontractor, Airflow Sciences Corporation, in support of an EPRI program. Airflow Sciences encountered significant difficulty getting the system up and running, with the final hurdles related to the system controls. These problems were resolved in this reporting period, so that the facility is ready for testing. Shakedown testing with our instrumentation package began late in the reporting period. Preliminary analysis of the resulting data indicates that there are problems with the instrumentation and/or test rig. Even with no flow passing through the test section, a power spectrum of the data shows strong frequency ''lines''. The data should be free of such behaviors, so the instrumentation must be recording behaviors that are unrelated to the flow. This issue must be resolved before calibration data are collected. A preliminary effort to debug the problem through long-distance consultation between Foster-Miller and Airflow Sciences personnel at the end of the reporting period did not discover the source of the problem. Consequently, a Foster-Miller engineer will visit the test facility early in the next reporting period. Assuming this effort is successful, preliminary testing and analysis should be completed in the next reporting period. Because of slack in the program schedule, there should be no net effect on the program scope, cost, or schedule.

  3. A pilot study to determine medical laser generated air contaminant emission rates for a simulated surgical procedure.

    PubMed

    Lippert, Julia F; Lacey, Steven E; Lopez, Ramon; Franke, John; Conroy, Lorraine; Breskey, John; Esmen, Nurtan; Liu, Li

    2014-01-01

    The U.S. Occupational Safety and Health Administration (OSHA) estimates that half a million health-care workers are exposed to laser surgical smoke each year. The purpose of this study was to establish a methodology to (1) estimate emission rates of laser-generated air contaminants (LGACs) using an emission chamber, and to (2) perform a screening study to differentiate the effects of three laser operational parameters. An emission chamber was designed, fabricated, and assessed for performance to estimate the emission rates of gases and particles associated with LGACs during a simulated surgical procedure. Two medical lasers (Holmium Yttrium Aluminum Garnet [Ho:YAG] and carbon dioxide [CO2]) were set to a range of plausible medical laser operational parameters in a simulated surgery to pyrolyze porcine skin generating plume in the emission chamber. Power, pulse repetition frequency (PRF), and beam diameter were evaluated to determine the effect of each operational parameter on emission rate using a fractional factorial design. The plume was sampled for particulate matter and seven gas phase combustion byproduct contaminants (benzene, ethylbenzene, toluene, formaldehyde, hydrogen cyanide, carbon dioxide, and carbon monoxide): the gas phase emission results are presented here. Most of the measured concentrations of gas phase contaminants were below their limit of detection (LOD), but detectable measurements enabled us to determine laser operation parameter influence on CO2 emissions. Confined to the experimental conditions of this screening study, results indicated that beam diameter was statistically significantly influential and power was marginally statistically significant to emission rates of CO2 when using the Ho:YAG laser but not with the carbon dioxide laser; PRF was not influential vis-a-vis emission rates of these gas phase contaminants. PMID:24498966

  4. Chemical characterization of indoor air of homes from communes in Xuan Wei, China, with high lung cancer mortality rate

    SciTech Connect

    Chuang, J.; Cao, S.; Xian, Y.; Harris, B.; Mumford, J.

    1992-01-01

    In a rural county, Xuan Wei, China, the lung cancer mortality rate is among China's highest, especially in women. This mortality rate is more associated with indoor air burning of smoky coal, as opposed to smokeless coal or wood, for cooking and heating under unvented conditions. Homes using different fuels from communes with high and low lung cancer mortality rates were sampled for particulate matter (<10 micrometers) and semivolatile organics. The fine particles obtained from homes using smoky coal contained highest concentrations of organic matter (> 70%), including PAH, followed by homes using wood and smokeless coal. The major components present in the smoky coal filter samples were PAH and alkylated PAH. The smokeless coal filter samples exhibited profiles which were similar to the smoky coal samples except that some sulfur compounds were found. The estimated concentration levels of PAH in the smokeless coal samples were about one to two orders of magnitude lower than those of the smoky coal samples. In addition to PAH, aliphatic compounds and fatty acids were the major components found in the wood samples. Selected sample extracts from homes using smoky coal were fractionated into four fractions, and the results showed that the PAH and polar fractions have high mutagenic activity. Chemical characterization of the PAH fraction indicated that concentrations of some alkylated PAH were higher than those of their parent compounds. Chemical characterization of the polar fractions showed that nitrogen heterocyclic compounds are present.

  5. Chemical characterization of indoor air of homes from communes in Xuan Wei, China, with high lung cancer mortality rate

    NASA Astrophysics Data System (ADS)

    Chuang, J. C.; Cao, S. R.; Xian, Y. L.; Harris, D. B.; Mumford, J. L.

    In a rural county, Xuan Wei, China, the lung cancer mortality rate is among China's highest, especially in women. This mortality rate is more associated with indoor air burning of smoky coal, as opposed to smokeless coal or wood, for cooking and heating under unvented conditions. Homes using different fuels from communes with high and low lung cancer mortality rates were sampled for particulate matter (< 10 μm) and semivolatile organics. The fine particles obtained from homes using smoky coal contained highest concentrations of organic matter (> 70%), including PAH, followed by homes using wood and smokeless coal. The major components present in the smoky coal filter samples were PAH and alkylated PAH. The smokeless coal filter samples exhibited profiles which were similar to the smoky coal samples except that some sulfur compounds were found. The estimated concentration levels of PAH in the smokeless coal samples were about one to two orders of magnitude lower than those of the smoky coal samples. In addition to PAH, aliphatic compounds and fatty acids were the major components found in the wood samples. Selected sample extracts from homes using smoky coal were fractionated into four fractions, and the results showed that the PAH and polar fractions have high mutagenic activity. Chemical characterization of the PAH fraction indicated that concentrations of some alkylated PAH were higher than those of their parent compounds. Chemical characterization of the polar fractions showed that nitrogen heterocyclic compounds are present.

  6. Combustion rate limits of hydrogen plus hydrocarbon fuel: Air diffusion flames from an opposed jet burner technique

    NASA Technical Reports Server (NTRS)

    Pellett, Gerald L.; Guerra, Rosemary; Wilson, Lloyd G.; Reeves, Ronald N.; Northam, G. Burton

    1987-01-01

    Combustion of H2/hydrocarbon (HC) fuel mixtures may be considered in certain volume-limited supersonic airbreathing propulsion applications. Effects of HC addition to H2 were evaluated, using a recent argon-bathed, coaxial, tubular opposed jet burner (OJB) technique to measure the extinction limits of counterflow diffusion flames. The OJB flames were formed by a laminar jet of (N2 and/or HC)-diluted H2 mixture opposed by a similar jet of air at ambient conditions. The OJB data, derived from respective binary mixtures of H2 and methane, ethylene, or propane HCs, were used to characterize BLOWOFF and RESTORE. BLOWOFF is a sudden breaking of the dish-shaped OJB flame to a stable torus or ring shape, and RESTORE marks sudden restoration of the central flame by radial inward flame propagation. BLOWOFF is a measure of kinetically-limited flame reactivity/speed under highly stretched, but relatively ideal impingement flow conditions. RESTORE measures inward radial flame propagation rate, which is sensitive to ignition processes in the cool central core. It is concluded that relatively small molar amounts of added HC greatly reduce the reactivity characteristics of counterflow hydrogen-air diffusion flames, for ambient initial conditions.

  7. Influence of specimen size, tray inclination and air flow rate on the emission of gases from biomass combustion

    NASA Astrophysics Data System (ADS)

    Amorim, E. B.; Carvalho, J. A.; Soares Neto, T. G.; Anselmo, E.; Saito, V. O.; Dias, F. F.; Santos, J. C.

    2013-08-01

    Experiments of biomass combustion were performed to determine whether specimen size, tray inclination, or combustion air flow rate was the factor that most affects the emission of carbon dioxide, carbon monoxide, and methane. The chosen biomass was Eucalyptus citriodora, a very abundant species in Brazil, utilized in many industrial applications, including combustion for energy generation. Analyses by gas chromatograph and specific online instruments were used to determine the concentrations of the main emitted gases, and the following figures were found for the emission factors: 1400 ± 101 g kg-1 of CO2, 50 ± 13 g kg-1 of CO, and 3.2 ± 0.5 g kg-1 of CH4, which agree with values published in the literature for biomass from the Amazon rainforest. Statistical analysis of the experiments determined that specimen size most significantly affected the emission of gases, especially CO2 and CO.

  8. Analysis of anastomotic leakage after rectal surgery: A case-control study

    PubMed Central

    Tanaka, Junichiro; Nishikawa, Takeshi; Tanaka, Toshiaki; Kiyomatsu, Tomomichi; Hata, Keisuke; Kawai, Kazushige; Kazama, Shinsuke; Nozawa, Hiroaki; Yamaguchi, Hironori; Ishihara, Soichiro; Sunami, Eiji; Kitayama, Joji; Watanabe, Toshiaki

    2015-01-01

    Background The incidence of anastomotic leakage in rectal surgery is around 10 percent. Poor blood supply to the anastomosis, high anastomotic pressure and tension, increased operative blood loss, long operative time, and male sex are risk factors of anastomotic leakage. In the present study, we examined anastomotic leakage cases in rectal surgery at our institute and tried to ascertain the risk factors. Methods Three hundred fifty-seven consecutive patients who underwent rectal resection with anastomosis between January 2008 and October 2013 were included in the study. Patients were divided into two groups according to the existence of anastomotic leakage. Clinicopathological features, operative procedures, and intraoperative outcomes were compared between the two groups. Regarding intraoperative procedure, we focused on the ligation level of the inferior mesenteric artery, installing a transanal drainage tube in the rectum, and constructing a diverting stoma. Results Anastomotic leakage occurred in eight patients. All of them were male (p = 0.0284). There were no statistical differences in other characteristics of the patients or tumors, in operative procedures, or in intraoperative outcomes. Conclusions In the present study, no statistically significant risk factors for anastomotic leakage in rectal surgery were detected, except for male sex. However, the rate of anastomotic leakage at our institute was revealed to be rather low. Our exertion to preserve good blood flow and to prevent high tension and pressure on the anastomosis in operation may have led to this result. PMID:26042185

  9. Heart Rate and Heart Rate Variability Assessment Identifies Individual Differences in Fear Response Magnitudes to Earthquake, Free Fall, and Air Puff in Mice

    PubMed Central

    Kuang, Hui; Tsien, Joe Z.; Zhao, Fang

    2014-01-01

    Fear behaviors and fear memories in rodents have been traditionally assessed by the amount of freezing upon the presentation of conditioned cues or unconditioned stimuli. However, many experiences, such as encountering earthquakes or accidental fall from tree branches, may produce long-lasting fear memories but are behaviorally difficult to measure using freezing parameters. Here, we have examined changes in heartbeat interval dynamics as physiological readout for assessing fearful reactions as mice were subjected to sudden air puff, free-fall drop inside a small elevator, and a laboratory-version earthquake. We showed that these fearful events rapidly increased heart rate (HR) with simultaneous reduction of heart rate variability (HRV). Cardiac changes can be further analyzed in details by measuring three distinct phases: namely, the rapid rising phase in HR, the maximum plateau phase during which HRV is greatly decreased, and the recovery phase during which HR gradually recovers to baseline values. We showed that durations of the maximum plateau phase and HR recovery speed were quite sensitive to habituation over repeated trials. Moreover, we have developed the fear resistance index based on specific cardiac response features. We demonstrated that the fear resistance index remained largely consistent across distinct fearful events in a given animal, thereby enabling us to compare and rank individual mouse’s fear responsiveness among the group. Therefore, the fear resistance index described here can represent a useful parameter for measuring personality traits or individual differences in stress-susceptibility in both wild-type mice and post-traumatic stress disorder (PTSD) models. PMID:24667366

  10. Determining air pollutant emission rates based on mass balance using airborne measurement data over the Alberta oil sands operations

    NASA Astrophysics Data System (ADS)

    Gordon, M.; Li, S.-M.; Staebler, R.; Darlington, A.; Hayden, K.; O'Brien, J.; Wolde, M.

    2015-09-01

    Top-down approaches to measure total integrated emissions provide verification of bottom-up, temporally resolved, inventory-based estimations. Aircraft-based measurements of air pollutants from sources in the Canadian oil sands were made in support of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring during a summer intensive field campaign between 13 August and 7 September 2013. The measurements contribute to knowledge needed in support of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring. This paper describes the top-down emission rate retrieval algorithm (TERRA) to determine facility emissions of pollutants, using SO2 and CH4 as examples, based on the aircraft measurements. In this algorithm, the flight path around a facility at multiple heights is mapped to a two-dimensional vertical screen surrounding the facility. The total transport of SO2 and CH4 through this screen is calculated using aircraft wind measurements, and facility emissions are then calculated based on the divergence theorem with estimations of box-top losses, horizontal and vertical turbulent fluxes, surface deposition, and apparent losses due to air densification and chemical reaction. Example calculations for two separate flights are presented. During an upset condition of SO2 emissions on one day, these calculations are within 5 % of the industry-reported, bottom-up measurements. During a return to normal operating conditions, the SO2 emissions are within 11 % of industry-reported, bottom-up measurements. CH4 emissions calculated with the algorithm are relatively constant within the range of uncertainties. Uncertainty of the emission rates is estimated as less than 30 %, which is primarily due to the unknown SO2 and CH4 mixing ratios near the surface below the lowest flight level.

  11. 42 CFR 84.182 - Exhalation valve leakage test; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Exhalation valve leakage test; minimum requirements. 84.182 Section 84.182 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Non-Powered Air-Purifying...

  12. Regulatory concerns for leakage testing of packagings with three O-ring closure seals

    SciTech Connect

    Oras, J.J.; Towell, R.H.; Wangler, M.E.

    1997-09-01

    The American National Standard for Radioactive Materials--Leakage Tests on Packages for Shipment (ANSI N14.5) provides guidance for leakage rate testing to show that a particular packaging complies with regulatory requirements and also provides guidance in determining appropriate acceptance criteria. Recent radioactive packagings designs have incorporated three O-ring closure seals, the middle O-ring being the containment seal. These designs have the potential for false positive results of leakage rate tests. The volume between the containment O-ring and the inner O-ring is used for the helium gas required for the leakage rate tests to reduce both the amount of helium used and the time required to conduct the tests. A leak detector samples the evacuated volume between the outer O-ring and the containment O-ring. False positive results can be caused in two ways, a large leakage in the containment seal or leakage in the inner seal. This paper will describe the problem together with possible solutions/areas that need to be addressed in a Safety Analysis Report for Packagings before a particular packaging design can be certified for transport.

  13. Rate and extent of leakage of a magnetic resonance contrast agent tend to be lower under isoflurane anesthesia in comparison to halothane in a rat model of embolic stroke.

    PubMed

    Bezerra, Francisco J; Brown, Morris; Alarcon, William; Karki, Kishor; Knight, Robert A; Keenan, Kelly A; Nagaraja, Tavarekere N

    2014-09-01

    Cerebral blood flow (CBF) and blood-brain barrier (BBB) permeability by arterial spin labeling (ASL)- and dynamic contrast enhanced (DCE)-magnetic resonance imaging (MRI), respectively were repeatedly measured under either halothane (N  =  5) or isoflurane (N  =  5) anesthesia in a rat stroke model of embolic occlusion of middle cerebral artery (MCA). Cerebral blood flow measurements were made after MCA embolization, following intravenous recombinant tissue plasminogen activator (rtPA) treatment at 3 hours post-ictus and again at 48 hours. Blood-brain barrier opening was examined after rtPA infusion and again at 48 hours. Data were analyzed using paired t-tests and significance considered at P < 0·05. The extent and magnitude of CBF reduction due to stroke did not differ between the two groups. Blood-to-brain forward rate constant, K(trans), a measure of BBB permeability, for an MRI contrast agent gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), was elevated in the ipsilateral hemisphere in both cohorts. However, isoflurane-anesthetized rats exhibited a trend of lower K(trans) values at 48 hours (P  =  0·06) indicating reduced BBB damage in the ipsilateral hemisphere. The area of BBB opening followed a similar trend with the isoflurane-anesthetized group exhibiting a smaller area of BBB damage acutely and at 48 hours compared to the halothane-anesthetized group. PMID:24601723

  14. Delays in hiring Air Traffic Collegiate Training Initiative (AT-CTI) graduates and the impact on their training success rate

    NASA Astrophysics Data System (ADS)

    Jorgenson, Terra A.

    arrive at the FAA Academy. In addition, the effect of the wait on the success rate of training at the FAA Academy and at the candidate's first facility was examined. Data was collected to examine the relationship between a CTI graduate's performance in the CTI program and the individual's performance during FAA training at the FAA Academy and assignment to their first facility. Through correlation analysis of the Air Traffic Basics (AT-Basic), Air Traffic Selection and Training (AT-SAT) and Performance Verification (PV) scores there was significant correlation between the AT-Basic and PV scores. As the AT-Basic score increases so does the PV scores. There needs to be future research on GPA's, PV's, AT-SAT and AT-Basics scores to determine if any of them are predictors of CTI's success in training. If the FAA can better predict if an applicant will be successful in training, it can save the FAA money in the selection, hiring and training process.

  15. Brookhaven air infiltration measurement system (BNL/AIMS) description and application

    SciTech Connect

    Dietz, R.N.; Goodrich, R.W.; Cote, E.A.; Wieser, R.F.

    1983-08-01

    A unique capability to measure part-per-quadrillion concentrations of a family of perfluorocarbon tracers (PFTs) is presented. Together with our unique PFT source and passive sampler, measurement of average air exchange and infiltration rate can be determined for periods as short as 12 hours. A more expensive programmable sampler can provide information on a frequency of as little as once per minute for each of its 23 sampling tubes. The principal of AIMS is based on the applicable steady-state assumption that the average concentration (e.g., in pL/L) of a tracer vapor in a chamber (i.e., a building or room) is equal to the emission rate of the tracer source (e.g., in pL/min) divided by the air leakage or infiltration rate (e.g., in L/min). Knowing the source rate and measuring the average concentration then provides a means to calculate the air leakage rate. Extending this technique to a multichamber concept, in which a different type of PFT source is deployed in each chamber of a building, allows the calculation of not only the infiltration rates in each chamber but also the air exchange rates between chambers as well. Since both the PFT source and the passive sampler, a miniature Capillary Adsorption Tube Sampler (CATS), are about the size of a cigarette, inexpensive, and reusable, the BNL/AIMS is a very cost-effective means (if not the only means) for determining these air exchange rates.

  16. Free-air CO{sub 2} enrichment effects on rate and duration of apical development of spring wheat

    SciTech Connect

    Li, Ai-Guo; Trent, A.; Wall, G.W.; Kimball, B.A.

    1997-05-01

    Rates and durations of individual phases of wheat (Triticum aestivum L.) apical development are among the most important factors that determine yield components. Because atmospheric CO{sub 2} has been increasing steadily, it is important to evaluate the effects of elevated CO{sub 2} on wheat development. This study was conducted to determine rates and durations of leaf, spikelet, and floret primordium initiation in a Free-Air Carbon Dioxide Enrichment (FACE) system. Spring wheat (cv. Yecora Roja) was planted at the University of Arizona Maricopa Agricultural Center. The two CO{sub 2} concentrations were 550 (elevated) and 370 (ambient) {mu}mol mol{sup -1} CO{sub 2}. Individual plant samples were collected every 3 to 4 d. We dissected the main stem (MS), coleoptile tiller (T0), primary tillers (T1, T2, and T3) and secondary tillers (T00, T01, T02, T10, T11, and T12) and counted primordia. Apex primordium data were fitted to a four-piece linear-spline segmented regression model with the SAS proc NLIN. No influence of elevated CO{sub 2} (550 {mu}mol mol{sup -1}) on leaf primordium initiation of MS was detected. Nevertheless, CO{sub 2} enrichment significantly increased was detected. Nevertheless, CO{sub 2} enrichment significantly increased rates of spikelet primordium initiation of MS, T1, T2, T10, and T11, and diminished the durations of spikelet development phase of MS, T1, T2, T3, T10, and T11. Within the floret phase, CO{sub 2} enrichment significantly increased rates of floret primordium initiation of MS, floret primordium initiation of MS, T0, T1, T3, and T11. The information from this study will be utilized to predict wheat apical development and grain production in the elevated atmospheric CO{sub 2} environments of the future. 40 refs., 4 figs., 5 tabs.

  17. Total inward leakage of nanoparticles through filtering facepiece respirators.

    PubMed

    Rengasamy, Samy; Eimer, Benjamin C

    2011-04-01

    Nanoparticle (<100 nm size) exposure in workplaces is a major concern because of the potential impact on human health. National Institute for Occupational Safety and Health (NIOSH)-approved particulate respirators are recommended for protection against nanoparticles based on their filtration efficiency at sealed conditions. Concerns have been raised on the lack of information for face seal leakage of nanoparticles, compromising respiratory protection in workplaces. To address this issue, filter penetration and total inward leakage (TIL) through artificial leaks were measured for NIOSH-approved N95 and P100 and European certified Conformit'e Europe'en-marked FFP2 and FFP3 filtering facepiece respirator models sealed to a breathing manikin kept inside a closed chamber. Monodisperse sucrose aerosols (8-80 nm size) generated by electrospray or polydisperse NaCl aerosols (20-1000 nm size) produced by atomization were passed into the chamber. Filter penetration and TIL were measured at 20, 30, and 40 l min(-1) breathing flow rates. The most penetrating particle size (MPPS) was ∼50 nm and filter penetrations for 50 and 100 nm size particles were markedly higher than the penetrations for 8 and 400 nm size particles. Filter penetrations increased with increasing flow rates. With artificially introduced leaks, the TIL values for all size particles increased with increasing leak sizes. With relatively smaller size leaks, the TIL measured for 50 nm size particles was ∼2-fold higher than the values for 8 and 400 nm size particles indicating that the TIL for the most penetrating particles was higher than for smaller and larger size particles. The data indicate that higher concentration of nanoparticles could occur inside the breathing zone of respirators in workplaces where nanoparticles in the MPPS range are present, when leakage is minimal compared to filter penetration. The TIL/penetration ratios obtained for 400 nm size particles were larger than the ratios obtained for

  18. 49 CFR 192.723 - Distribution systems: Leakage surveys.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Distribution systems: Leakage surveys. 192.723... Distribution systems: Leakage surveys. (a) Each operator of a distribution system shall conduct periodic leakage surveys in accordance with this section. (b) The type and scope of the leakage control...

  19. 49 CFR 192.723 - Distribution systems: Leakage surveys.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Distribution systems: Leakage surveys. 192.723... Distribution systems: Leakage surveys. (a) Each operator of a distribution system shall conduct periodic leakage surveys in accordance with this section. (b) The type and scope of the leakage control...

  20. 49 CFR 192.723 - Distribution systems: Leakage surveys.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Distribution systems: Leakage surveys. 192.723... Distribution systems: Leakage surveys. (a) Each operator of a distribution system shall conduct periodic leakage surveys in accordance with this section. (b) The type and scope of the leakage control...

  1. 49 CFR 192.723 - Distribution systems: Leakage surveys.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Distribution systems: Leakage surveys. 192.723... Distribution systems: Leakage surveys. (a) Each operator of a distribution system shall conduct periodic leakage surveys in accordance with this section. (b) The type and scope of the leakage control...

  2. 21 CFR 870.2640 - Portable leakage current alarm.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Portable leakage current alarm. 870.2640 Section... leakage current alarm. (a) Identification. A portable leakage current alarm is a device used to measure the electrical leakage current between any two points of an electrical system and to sound an alarm...

  3. 21 CFR 870.2640 - Portable leakage current alarm.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Portable leakage current alarm. 870.2640 Section... leakage current alarm. (a) Identification. A portable leakage current alarm is a device used to measure the electrical leakage current between any two points of an electrical system and to sound an alarm...

  4. 21 CFR 870.2640 - Portable leakage current alarm.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Portable leakage current alarm. 870.2640 Section... leakage current alarm. (a) Identification. A portable leakage current alarm is a device used to measure the electrical leakage current between any two points of an electrical system and to sound an alarm...

  5. 21 CFR 870.2640 - Portable leakage current alarm.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Portable leakage current alarm. 870.2640 Section... leakage current alarm. (a) Identification. A portable leakage current alarm is a device used to measure the electrical leakage current between any two points of an electrical system and to sound an alarm...

  6. 21 CFR 870.2640 - Portable leakage current alarm.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Portable leakage current alarm. 870.2640 Section... leakage current alarm. (a) Identification. A portable leakage current alarm is a device used to measure the electrical leakage current between any two points of an electrical system and to sound an alarm...

  7. Airtightness Results of Roof-Only Air Sealing Strategies on 1 ½-Story Homes in Cold Climates

    SciTech Connect

    Ojczyk, C.; Murry, T.; Mosiman, G.

    2014-07-01

    In this second study on solutions to ice dams in 1-1/2 story homes, the NorthernSTAR Building America Partnership team analyzed five test homes located in both cold and very cold climates for air leakage reduction rates following modifications by independent contractors on owner-occupied homes. These homes were chosen for testing as they are common in Minnesota and very difficult to air seal and insulate effectively. Two projects followed a roof-only Exterior Thermal Moisture Management System (ETMMS) process. One project used an interior-only approach to roof air sealing and insulation. The remaining two projects used a deep energy retrofit approach for whole house (foundation wall, above grade wall, roof) air leakage and heat loss reduction. All were asked to provide information regarding project goals, process, and pre and post-blower door test results. Additional air leakage reduction data was provided by several NorthernSTAR industry partners for interior-applied, roof-only modifications on 1-1/2 story homes. The data represents homes in the general market as well as homes that were part of the state of Minnesota weatherization program. A goal was to compare exterior air sealing methods with interior approaches. This pool of data enabled the team to compare air tightness data from over 220 homes using similar air seal methods.

  8. Airtightness Results of Roof-Only Air Sealing Strategies on 1-1/2 Story Homes in Cold Climates

    SciTech Connect

    Ojczyk, C.; Murry, T.; Mosiman, G.

    2014-07-01

    In this second study on solutions to ice dams in 1-1/2 story homes, five test homes located in both cold and very cold climates were analyzed for air leakage reduction rates following modifications by independent contractors on owner-occupied homes. The reason for choosing this house type was they are very common in our area and very difficult to air seal and insulate effectively. Two projects followed a roof-only Exterior Thermal Moisture Management System (ETMMS) process. One project used an interior-only approach to roof air sealing and insulation. The remaining two projects used a deep energy retrofit approach for whole house (foundation wall, above grade wall, roof) air leakage and heat loss reduction. All were asked to provide information regarding project goals, process, and pre and post-blower door test results. Additional air leakage reduction data was provided by several NorthernSTAR Building America industry partners for interior-applied, roof-only modifications on 1-1/2 story homes. The data represents homes in the general market as well as homes that were part of the state of Minnesota weatherization program. A goal was to compare exterior air sealing methods with interior approaches. This pool of data enabled us to compare air tightness data from over 220 homes using similar air seal methods.

  9. Air Force Seal Programs

    NASA Technical Reports Server (NTRS)

    Mayhew, Ellen R.

    1996-01-01

    Seal technology development is an important part of the Air Force's participation in the Integrated High Performance Turbine Engine Technology (IHPTET) initiative, the joint DOD, NASA, ARPA, and industry endeavor to double turbine engine capabilities by the turn of the century. Significant performance and efficiency improvements can be obtained through reducing internal flow system leakage, but seal environment requirements continue to become more extreme as the engine thermodynamic cycles advance towards these IHPTET goals. Seal technology continues to be pursued by the Air Force to control leakage at the required conditions. This presentation briefly describes current seal research and development programs and gives a summary of seal applications in demonstrator and developmental engines.

  10. Oxidation rate of nuclear-grade graphite NBG-18 in the kinetic regime for VHTR air ingress accident scenarios

    NASA Astrophysics Data System (ADS)

    Lee, Jo Jo; Ghosh, Tushar K.; Loyalka, Sudarshan K.

    2013-07-01

    One of the most severe accident scenarios anticipated for VHTRs is an air ingress accident caused by a pipe break. Graphite oxidation could be severe under these conditions. In this work, the oxidation rate of NBG-18 nuclear-grade graphite was studied thermogravimetrically for different oxygen concentrations and with temperatures from 873 to 1873 K. A semi-empirical Arrhenius rate equation was developed for the temperature range of 873-1023 K. The activation energy of NBG-18 was 187 kJ/mol and the order of reaction was 1.25. The penetration depth of oxidant was about 3-4 mm for NBG-18 oxidized at 973 K. Increased porosity and changes in external geometry became more prominent at higher temperatures from about 1173 to 1873 K. The surface of oxidized NBG-18 was characterized by SEM, EDS, FTIR and XPS. Diffusion of oxygen to the graphite surface and walls of open volume pores. Adsorption of oxygen atoms on the graphite surface free active sites and complexes inducing the simultaneous forming of Csbnd O and Csbnd H bonds and breaking of Csbnd C bonds (dissociative chemisorption). Chemical reactions occur at the surface. Desorption of gaseous products, CO and CO2, from the graphite surface and transport to the bulk gas mixture.

  11. Thermally Induced Leakage from Vibrio marinus, an Obligately Psychrophilic Marine Bacterium1

    PubMed Central

    Haight, Roger D.; Morita, Richard Y.

    1966-01-01

    Haight, Rodger D. (Oregon State University, Corvallis), and Richard Y. Morita. Thermally induced leakage from Vibrio marinus, an obligately psychrophilic bacterium. J. Bacteriol. 92:1388–1393. 1966.—Leakage of various cellular components into the surrounding menstruum occurred when Vibrio marinus was subjected to temperatures above 20 C (organism's maximal growth temperature). These materials, listed in decreasing rates of leakage, were identified as protein, deoxyribonucleic acid, ribonucleic acid, and amino acids. The amount of polar amino acids increased as the time and temperature of heat treatment were increased, whereas the nonpolar amino acids decreased. The ribonucleic acid in the supernatant fluid resulting from heat treatment was both polymeric and nonpolymeric. Leakage of cellular components may be one of the reasons that V. marinus MP-1 loses viability when exposed to temperatures above its maximal temperature for growth. PMID:5924270

  12. Health risks following ingestion of mercury and zinc air batteries.

    PubMed

    Nolan, M; Tucker, I

    1981-01-01

    This paper reports on a study set up to assess the corrosive behaviour of mercury and zinc air batteries in the gastric juice environment of the stomach. The results show a relatively rapid rate of corrosion for charged mercury batteries. In contrast, the zinc air battery showed no visible corrosion under the same conditions. In view of the toxic dangers from leakage of mercury batteries, it is recommended that steps be taken to ensure that such batteries do not remain in the acidic environment of the stomach, should ingestion occur. PMID:7302525

  13. ANEMOS: A computer code to estimate air concentrations and ground deposition rates for atmospheric nuclides emitted from multiple operating sources

    SciTech Connect

    Miller, C.W.; Sjoreen, A.L.; Begovich, C.L.; Hermann, O.W.

    1986-11-01

    This code estimates concentrations in air and ground deposition rates for Atmospheric Nuclides Emitted from Multiple Operating Sources. ANEMOS is one component of an integrated Computerized Radiological Risk Investigation System (CRRIS) developed for the US Environmental Protection Agency (EPA) for use in performing radiological assessments and in developing radiation standards. The concentrations and deposition rates calculated by ANEMOS are used in subsequent portions of the CRRIS for estimating doses and risks to man. The calculations made in ANEMOS are based on the use of a straight-line Gaussian plume atmospheric dispersion model with both dry and wet deposition parameter options. The code will accommodate a ground-level or elevated point and area source or windblown source. Adjustments may be made during the calculations for surface roughness, building wake effects, terrain height, wind speed at the height of release, the variation in plume rise as a function of downwind distance, and the in-growth and decay of daughter products in the plume as it travels downwind. ANEMOS can also accommodate multiple particle sizes and clearance classes, and it may be used to calculate the dose from a finite plume of gamma-ray-emitting radionuclides passing overhead. The output of this code is presented for 16 sectors of a circular grid. ANEMOS can calculate both the sector-average concentrations and deposition rates at a given set of downwind distances in each sector and the average of these quantities over an area within each sector bounded by two successive downwind distances. ANEMOS is designed to be used primarily for continuous, long-term radionuclide releases. This report describes the models used in the code, their computer implementation, the uncertainty associated with their use, and the use of ANEMOS in conjunction with other codes in the CRRIS. A listing of the code is included in Appendix C.

  14. Ambient particulate air pollution, heart rate variability, and blood markers of inflammation in a panel of elderly subjects.

    PubMed Central

    Pope, C Arden; Hansen, Matthew L; Long, Russell W; Nielsen, Karen R; Eatough, Norman L; Wilson, William E; Eatough, Delbert J

    2004-01-01

    Epidemiologic studies report associations between particulate air pollution and cardiopulmonary morbidity and mortality. Although the underlying pathophysiologic mechanisms remain unclear, it has been hypothesized that altered autonomic function and pulmonary/systemic inflammation may play a role. In this study we explored the effects of air pollution on autonomic function measured by changes in heart rate variability (HRV) and blood markers of inflammation in a panel of 88 elderly subjects from three communities along the Wasatch Front in Utah. Subjects participated in multiple sessions of 24-hr ambulatory electrocardiographic monitoring and blood tests. Regression analysis was used to evaluate associations between fine particulate matter [aerodynamic diameter less than or equal to 2.5 microm (PM2.5)] and HRV, C-reactive protein (CRP), blood cell counts, and whole blood viscosity. A 100- microg/m3 increase in PM2.5 was associated with approximately a 35 (SE = 8)-msec decline in standard deviation of all normal R-R intervals (SDNN, a measure of overall HRV); a 42 (SE = 11)-msec decline in square root of the mean of the squared differences between adjacent normal R-R intervals (r-MSSD, an estimate of short-term components of HRV); and a 0.81 (SE = 0.17)-mg/dL increase in CRP. The PM2.5-HRV associations were reasonably consistent and statistically robust, but the CRP association dropped to 0.19 (SE = 0.10) after excluding the most influential subject. PM2.5 was not significantly associated with white or red blood cell counts, platelets, or whole-blood viscosity. Most short-term variability in temporal deviations of HRV and CRP was not explained by PM2.5; however, the small statistically significant associations that were observed suggest that exposure to PM2.5 may be one of multiple factors that influence HRV and CRP. PMID:14998750

  15. The characteristics of coarse particulate matter air pollution associated with alterations in blood pressure and heart rate during controlled exposures

    PubMed Central

    Morishita, Masako; Bard, Robert L.; Wang, Lu; Das, Ritabrata; Dvonch, J. Timothy; Spino, Catherine; Mukherjee, Bhramar; Sun, Qinghua; Harkema, Jack R.; Rajagopalan, Sanjay; Brook, Robert D.

    2015-01-01

    Although fine particulate matter (PM) air pollution <2.5 μm in aerodynamic diameter (PM2.5) is a leading cause of global morbidity and mortality, the potential health effects of coarse PM (2.5–10 μm in aerodynamic diameter; PM10–2.5) remain less clearly understood. We aimed to elucidate the components within coarse PM most likely responsible for mediating these hemodynamic alterations. Thirty-two healthy adults (25.9 ± 6.6 years) were exposed to concentrated ambient coarse PM (CAP) (76.2 ± 51.5 μg/m3) and filtered air (FA) for 2 h in a rural location in a randomized double-blind crossover study. The particle constituents (24 individual elements, organic and elemental carbon) were analyzed from filter samples and associated with the blood pressure (BP) and heart rate (HR) changes occurring throughout CAP and FA exposures in mixed model analyses. Total coarse PM mass along with most of the measured elements were positively associated with similar degrees of elevations in both systolic BP and HR. Conversely, total PM mass was unrelated, whereas only two elements (Cu and Mo) were positively associated with and Zn was inversely related to diastolic BP changes during exposures. Inhalation of coarse PM from a rural location rapidly elevates systolic BP and HR in a concentration-responsive manner, whereas the particulate composition does not appear to be an important determinant of these responses. Conversely, exposure to certain PM elements may be necessary to trigger a concomitant increase in diastolic BP. These findings suggest that particulate mass may be an adequate metric of exposure to predict some, but not all, hemodynamic alterations induced by coarse PM mass. PMID:25227729

  16. Modeling Spatial and Temporal Variability of Residential Air Exchange Rates for the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS)

    EPA Science Inventory

    Air pollution health studies often use outdoor concentrations as exposure surrogates. Failure to account for variability of residential infiltration of outdoor pollutants can induce exposure errors and lead to bias and incorrect confidence intervals in health effect estimates. Th...

  17. Modeling air pollutant emissions from Indian auto-rickshaws: Model development and implications for fleet emission rate estimates

    NASA Astrophysics Data System (ADS)

    Grieshop, Andrew P.; Boland, Daniel; Reynolds, Conor C. O.; Gouge, Brian; Apte, Joshua S.; Rogak, Steven N.; Kandlikar, Milind

    2012-04-01

    Chassis dynamometer tests were conducted on 40 Indian auto-rickshaws with 3 different fuel-engine combinations operating on the Indian Drive Cycle (IDC). Second-by-second (1 Hz) data were collected and used to develop velocity-acceleration look-up table models for fuel consumption and emissions of CO2, CO, total hydrocarbons (THC), oxides of nitrogen (NOx) and fine particulate matter (PM2.5) for each fuel-engine combination. Models were constructed based on group-average vehicle activity and emissions data in order to represent the performance of a 'typical' vehicle. The models accurately estimated full-cycle emissions for most species, though pollutants with more variable emission rates (e.g., PM2.5) were associated with larger errors. Vehicle emissions data showed large variability for single vehicles ('intra-vehicle variability') and within the test group ('inter-vehicle variability'), complicating the development of a single model to represent a vehicle population. To evaluate the impact of this variability, sensitivity analyses were conducted using vehicle activity data other than the IDC as model input. Inter-vehicle variability dominated the uncertainty in vehicle emission modeling. 'Leave-one-out' analyses indicated that the model outputs were relatively insensitive to the specific sample of vehicles and that the vehicle samples were likely a reasonable representation of the Delhi fleet. Intra-vehicle variability in emissions was also substantial, though had a relatively minor impact on model performance. The models were used to assess whether the IDC, used for emission factor development in India, accurately represents emissions from on-road driving. Modeling based on Global Positioning System (GPS) activity data from real-world auto-rickshaws suggests that, relative to on-road vehicles in Delhi, the IDC systematically under-estimates fuel use and emissions; real-word auto-rickshaws consume 15% more fuel and emit 49% more THC and 16% more PM2.5. The models

  18. Influence of air flow rate on emission of DEHP from vinyl flooring in the emission cell FLEC: Measurements and CFD simulation

    NASA Astrophysics Data System (ADS)

    Clausen, Per Axel; Liu, Zhe; Xu, Ying; Kofoed-Sørensen, Vivi; Little, John C.

    2010-07-01

    The emission of di-(2-ethylhexyl)phthalate (DEHP) from one type of vinyl flooring with ˜15% (w/w) DEHP as plasticizer was measured at 22 °C in five FLECs + one blank FLEC (Field and Laboratory Emission Cell). Initially, the flow through all FLECs was 450 ml min -1. After 689 days the flows were changed to 1000 ml min -1, 1600 ml min -1, 2300 ml min -1, and 3000 ml min -1, respectively, in four FLECs, and kept at 450 ml min -1 in one FLEC. Air samples were collected from the effluent air at regular intervals. After 1190 days the experiments were terminated and the interior surfaces of all six FLECs were rinsed with methanol to estimate the internal surface concentrations of DEHP. The DEHP air concentration and specific emission rate (SER) at steady state was estimated for the five different flow rates. The steady-state concentrations decreased slightly with increasing air flow with only the two highest flow rates resulting in significantly lower concentrations. In contrast, the SERs increased significantly. Despite large variation, the internal surface concentrations appeared to decrease slightly with increasing FLEC flow. Computational fluid dynamic (CFD) simulations suggest that the interior gas and surface concentrations were roughly uniform for the low flow case (450 ml min -1), under which, the partitioning between the FLEC internal surface and chamber air was examined. Although paired t-tests showed no difference between CFD and experimental results for DEHP air concentrations and SERs at steady-state conditions, CFD indicated that the experimental DEHP surface concentrations in the FLECs were underestimated. In conclusion, the experiments showed that the emission of DEHP from vinyl flooring is subject to "external" control and that the SER is strongly and positively dependent on the air exchange rate. However, the increased SER almost compensates for the decrease in gas-phase concentration caused by the increased air exchange.

  19. A review of reaction rates and thermodynamic and transport properties for the 11-species air model for chemical and thermal nonequilibrium calculations to 30000 K

    NASA Technical Reports Server (NTRS)

    Gupta, Roop N.; Yos, Jerrold M.; Thompson, Richard A.

    1989-01-01

    Reaction rate coefficients and thermodynamic and transport properties are provided for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in such environments.

  20. Component external leakage and rupture frequency estimates

    SciTech Connect

    Eide, S.A.; Khericha, S.T.; Calley, M.B.; Johnson, D.A.; Marteeny, M.L.

    1991-11-01

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

  1. Error analysis for duct leakage tests in ASHRAE standard 152P

    SciTech Connect

    Andrews, J.W.

    1997-06-01

    This report presents an analysis of random uncertainties in the two methods of testing for duct leakage in Standard 152P of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). The test method is titled Standard Method of Test for Determining Steady-State and Seasonal Efficiency of Residential Thermal Distribution Systems. Equations have been derived for the uncertainties in duct leakage for given levels of uncertainty in the measured quantities used as inputs to the calculations. Tables of allowed errors in each of these independent variables, consistent with fixed criteria of overall allowed error, have been developed.

  2. Multicenter Analysis of Long-Term Oncologic Impact of Anastomotic Leakage After Laparoscopic Total Mesorectal Excision

    PubMed Central

    Kang, Jeonghyun; Choi, Gyu-Seog; Oh, Jae Hwan; Kim, Nam Kyu; Park, Jun Seok; Kim, Min Jung; Lee, Kang Young; Baik, Seung Hyuk

    2015-01-01

    Abstract This study aims to validate the oncologic outcomes of anastomotic leakage (AL) after laparoscopic total mesorectal excision (TME) in a large multicenter cohort. The impact of AL after laparoscopic TME for rectal cancer surgery has not yet been clearly described. This was a multicenter retrospective study of 1083 patients who underwent laparoscopic TME for nonmetastatic rectal cancer (stage 0–III). AL was defined as an anastomotic complication within 30 days of surgery irrespective of requiring a reoperation or interventional radiology. Estimated local recurrence (LR), disease-free survival (DFS), and overall survival (OS) were compared between the leakage group and the no leakage group using the log-rank method. Multivariate Cox-regression analysis was used to adjust confounding for survival. The incidence of AL was 6.4%. Mortality within 30 days of surgery occurred in 1 patient (1.4%) in the leakage group and 2 patients (0.2%) in the no leakage group. The leakage group showed a higher LR rate (6.4% vs 1.8%, P = 0.011). Five-year DFS and OS were significantly lower in the leakage group than the no leakage group (DFS 71.7% vs 82.1%, P = 0.016, OS 81.8% vs 93.5%, P = 0.007). Multivariate analysis showed that AL was an independent poor prognostic factor for DFS and OS (hazard ratio [HR] = 1.6; 95% confidence intervals [CI]: 1.0–2.6; P = 0.042, HR = 2.1; 95% CI: 1.0–4.2; P = 0.028, respectively). AL after laparoscopic TME was significantly associated with an increased rate of LR, systemic recurrence and poor OS. PMID:26200636

  3. Challenges of Achieving 2012 IECC Air Sealing Requirements in Multifamily Dwellings

    SciTech Connect

    Klocke, S.; Faakye, O.; Puttagunta, S.

    2014-10-01

    ​While previous versions of the International Energy Conservation Code (IECC) have included provisions to improve the air tightness of dwellings, for the first time, the 2012 IECC mandates compliance verification through blower door testing. Simply completing the Air Barrier and Insulation Installation checklist through visual inspection is no longer sufficient by itself. In addition, the 2012 IECC mandates a significantly stricter air sealing requirement. In Climate Zones 3 through 8, air leakage may not exceed 3 ACH50, which is a significant reduction from the 2009 IECC requirement of 7 ACH50. This requirement is for all residential buildings, which includes low-rise multifamily dwellings. While this air leakage rate requirement is an important component to achieving an efficient building thermal envelope, currently, the code language doesn't explicitly address differences between single family and multifamily applications. In addition, the 2012 IECC does not provide an option to sample dwellings for larger multifamily buildings, so compliance would have to be verified on every unit. With compliance with the 2012 IECC air leakage requirements on the horizon, several of CARB's multifamily builder partners are evaluating how best to comply with this requirement. Builders are not sure whether it is more practical or beneficial to simply pay for guarded testing or to revise their air sealing strategies to improve compartmentalization to comply with code requirements based on unguarded blower door testing. This report summarizes CARB's research that was conducted to assess the feasibility of meeting the 2012 IECC air leakage requirements in 3 multifamily buildings.

  4. Challenges of Achieving 2012 IECC Air Sealing Requirements in Multifamily Dwellings

    SciTech Connect

    Klocke, S.; Faakye, O.; Puttagunta, S.

    2014-10-01

    While previous versions of the International Energy Conservation Code (IECC) have included provisions to improve the air tightness of dwellings, for the first time, the 2012 IECC mandates compliance verification through blower door testing. Simply completing the Air Barrier and Insulation Installation checklist through visual inspection is no longer sufficient by itself. In addition, the 2012 IECC mandates a significantly stricter air sealing requirement. In Climate Zones 3 through 8, air leakage may not exceed 3 ACH50, which is a significant reduction from the 2009 IECC requirement of 7 ACH50. This requirement is for all residential buildings, which includes low-rise multifamily dwellings. While this air leakage rate requirement is an important component to achieving an efficient building thermal envelope, currently, the code language doesn't explicitly address differences between single family and multifamily applications. In addition, the 2012 IECC does not provide an option to sample dwellings for larger multifamily buildings, so compliance would have to be verified on every unit. With compliance with the 2012 IECC air leakage requirements on the horizon, several of Consortium for Advanced Residential Building's (CARB’s) multifamily builder partners are evaluating how best to comply with this requirement. Builders are not sure whether it is more practical or beneficial to simply pay for guarded testing or to revise their air sealing strategies to improve compartmentalization to comply with code requirements based on unguarded blower door testing. This report summarizes CARB's research that was conducted to assess the feasibility of meeting the 2012 IECC air leakage requirements in 3 multifamily buildings.

  5. Accounting for geochemical alterations of caprock fracture permeability in basin-scale models of leakage from geologic CO2 reservoirs

    NASA Astrophysics Data System (ADS)

    Guo, B.; Fitts, J. P.; Dobossy, M.; Bielicki, J. M.; Peters, C. A.

    2012-12-01

    Climate mitigation, public acceptance and energy, markets demand that the potential CO2 leakage rates from geologic storage reservoirs are predicted to be low and are known to a high level of certainty. Current approaches to predict CO2 leakage rates assume constant permeability of leakage pathways (e.g., wellbores, faults, fractures). A reactive transport model was developed to account for geochemical alterations that result in permeability evolution of leakage pathways. The one-dimensional reactive transport model was coupled with the basin-scale Estimating Leakage Semi-Analytical (ELSA) model to simulate CO2 and brine leakage through vertical caprock pathways for different CO2 storage reservoir sites and injection scenarios within the Mt. Simon and St. Peter sandstone formations of the Michigan basin. Mineral dissolution in the numerical reactive transport model expands leakage pathways and increases permeability as a result of calcite dissolution by reactions driven by CO2-acidified brine. A geochemical model compared kinetic and equilibrium treatments of calcite dissolution within each grid block for each time step. For a single fracture, we investigated the effect of the reactions on leakage by performing sensitivity analyses of fracture geometry, CO2 concentration, calcite abundance, initial permeability, and pressure gradient. Assuming that calcite dissolution reaches equilibrium at each time step produces unrealistic scenarios of buffering and permeability evolution within fractures. Therefore, the reactive transport model with a kinetic treatment of calcite dissolution was coupled to the ELSA model and used to compare brine and CO2 leakage rates at a variety of potential geologic storage sites within the Michigan basin. The results are used to construct maps based on the susceptibility to geochemically driven increases in leakage rates. These maps should provide useful and easily communicated inputs into decision-making processes for siting geologic CO2

  6. Leakage Sign for Primary Intracerebral Hemorrhage

    PubMed Central

    Hirohata, Masaru; Nakamura, Yukihiko; Takeshige, Nobuyuki; Aoki, Takachika; Hattori, Gousuke; Sakata, Kiyohiko; Abe, Toshi; Uchiyama, Yuusuke; Sakamoto, Teruo; Morioka, Motohiro

    2016-01-01

    Background and Purpose— Recent studies of intracerebral hemorrhage treatments have highlighted the need to identify reliable predictors of hematoma expansion. Several studies have suggested that the spot sign on computed tomographic angiography (CTA) is a sensitive radiological predictor of hematoma expansion in the acute phase. However, the spot sign has low sensitivity for hematoma expansion. In this study, we evaluated the usefulness of a novel predictive method, called the leakage sign. Methods— We performed CTA for 80 consecutive patients presenting with spontaneous intracerebral hemorrhage. Two scans were completed: CTA phase and delayed phase (5 minutes after the CTA phase). By comparing the CTA phase images, we set a region of interest with a 10-mm diameter and calculated the Hounsfield units. We defined a positive leakage sign as a >10% increase in Hounsfield units in the region of interest. Additionally, hematoma expansion was determined on plain computed tomography at 24 hours in patients who did not undergo emergent surgery. Results— Positive spot signs and leakage signs were present in 18 (22%) patients and 35 (43%) patients, respectively. The leakage sign had higher sensitivity (93.3%) and specificity (88.9%) for hematoma expansion than the spot sign. The leakage sign, but not the spot sign, was significantly related with poor outcomes (severely disabled, vegetative state, and death) in all of the patients (P=0.03) and in patients with a hemorrhage in the putamen (P=0.0016). Conclusions— The results indicate that the leakage sign is a useful and sensitive method to predict hematoma expansion. PMID:26931155

  7. An evaluation of irritant smoke to detect exhalation valve leakage in respirators.

    PubMed

    Snyder, Erin M; McKay, Roy T

    2003-09-01

    This study evaluated the ability of a qualitative fit-test method (irritant smoke) to detect known exhalation valve leakage. The OSHA protocol for the irritant smoke test mandates the use of a low flow air pump at 200 mL/minute or an aspirator squeeze bulb. Many commercial test kits include an aspirator bulb, which is subject to variation in frequency, depth of squeeze, fatigue rate, and individual hand strength. Previous studies on irritant smoke used a handheld squeeze bulb. This study evaluated the effectiveness of a low flow pump for irritant smoke fit-testing. Twenty subjects wearing North 7600 series full-face respirators equipped with P100 filters were fit-tested with a Portacount Plus to ensure adequate fit. After successful fit was demonstrated, the exhalation valve was replaced with a damaged valve and/or rotated approximately 90 degrees to produce a fit factor below 100. Having induced an exhalation valve leak, the irritant smoke fit-test was performed using the OSHA irritant smoke protocol. To avoid introducing additional unknown leakage, all head movement exercises were replaced with the head straight, normal breathing maneuver. Irritant smoke did not detect 40 percent of respirators with leaking exhalation valves. Sixty percent of the subjects were able to detect the irritant smoke. Test sensitivity was 60 percent, well below the recommended 95 percent criterion. Of the 12 subjects that detected irritant smoke, none detected the smoke in less than a minute; the average detection time was 3 min 5 s. Some subjects were able to suppress the cough reflex. These findings suggest that qualitative fit-testing using irritant smoke with a 200 ml/min continuous flow pump does not have adequate sensitivity to detect fit factors less than 100. PMID:12909538

  8. Smog O3 Production Rate in California Air: Marker Compounds Allow Checks on Source Attribution to Fire and Other Sources

    NASA Astrophysics Data System (ADS)

    Chatfield, R. B.; Esswein, R. F.; Cai, C.; Kaduwela, A.; Kulkarni, S.; Blake, D. R.; Weinheimer, A. J.; Fried, A.; Huey, L. G.

    2012-12-01

    We are able to attribute sources of both radical reactivity and NO that determined the smog-chemical production rate of ozone, P(O3), for NASA's wide-ranging sampling of California air in June, 2008, part of the ARCTAS intensive. We relate formaldehyde, HCHO, and reactive nitrogen oxides, NOx, to a variety of distinct "marker" species that identify origins. We have labeled the sources and markers as (i) Fire emissions (CH3CN), (ii) Biogenic emissions (Isoprene), (iii) Urban/business emissions (CHCl3), (iv) Transport-related fuel consumption, (SO2), and (v) Refining/Port emissions ("residual" toluene). We use multiple linear regression with some appropriate restrictions. We achieve R-squared or explained variance of 88% for HCHO (VOC's) and 60% for NOx. HCHO and NOx are slowly evolving measures of potential ozone generation. The two related but radiation-influenced measures j (HCHO->H+HCO) x [HCHO] and [NO] quantitatively, but non-linearly, relate to instantaneous ozone production in California air, with R-squared of 86-93%, just as in New York City (Chatfield et al., Atmos. Environ., 2010). Maps of attribution for 650 samples from the Port of San Diego to the Northern Sierra foothills, and offshore -— all show huge variability in source attributions for VOCs and NOx. They indicate a widespread fire-emission influence on VOCs as they produce peroxy radicals, but show no positive influence on NOx, in fact consuming NOx from other sources. Comparisons with simulations help to refine our attribution classes and also to check balances of VOC emissions in available inventories. The use of the P(O3) measures is directly translatable to a method for estimate smog-ozone production rate from space, as data from another intensive, DISCOVER-AQ, show. (Left) A rare example where all sources contribute significantly, with markers and tentative attributions marked. (Right) Three different situations describing the control of smog ozone production, all from the same geographic

  9. Natural variation of ambient dose rate in the air of Izu-Oshima Island after the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Maedera, Fumihiko; Inoue, Kazumasa; Sugino, Masato; Sano, Ryosuke; Furue, Mai; Shimizu, Hideo; Tsuruoka, Hiroshi; Le Van, Tan; Fukushi, Masahiro

    2016-03-01

    The ambient dose rate in air and radioactivity concentration in soil samples collected on Izu-Oshima Island were observed in 2012, 2013 and 2014, i.e. 1, 2 and 3 years after the severe accident at the Fukushima Daiichi Nuclear Power Plant. A car-borne survey for the ambient dose rate in air was carried out for the entire island. Soil samples were collected for the radioactivity concentration measurements from 22 points. The ambient dose rates in air were 36 nGy h(-1) in 2012, 34 nGy h(-1) in 2013 and 29 nGy h(-1) in 2014. The corresponding radioactivity concentrations in those years for (134)Cs were 53, 39 and 29 Bq kg(-1) and for (137)Cs, 87, 73 and 75 Bq kg(-1). All the values have decreased every year. PMID:26246583

  10. A method to investigate inter-aquifer leakage using hydraulics and multiple environmental tracers

    NASA Astrophysics Data System (ADS)

    Priestley, Stacey; Love, Andrew; Wohling, Daniel; Post, Vincent; Shand, Paul; Kipfer, Rolf; Tyroller, Lina

    2016-04-01

    Informed aquifer management decisions regarding sustainable yields or potential exploitation require an understanding of the groundwater system (Alley et al. 2002, Cherry and Parker 2004). Recently, the increase in coal seam gas (CSG) or shale gas production has highlighted the need for a better understanding of inter-aquifer leakage and contaminant migration. In most groundwater systems, the quantity or location of inter-aquifer leakage is unknown. Not taking into account leakage rates in the analysis of large scale flow systems can also lead to significant errors in the estimates of groundwater flow rates in aquifers (Love et al. 1993, Toth 2009). There is an urgent need for robust methods to investigate inter-aquifer leakage at a regional scale. This study builds on previous groundwater flow and inter-aquifer leakage studies to provide a methodology to investigate inter-aquifer leakage in a regional sedimentary basin using hydraulics and a multi-tracer approach. The methodology incorporates geological, hydrogeological and hydrochemical information in the basin to determine the likelihood and location of inter-aquifer leakage. Of particular benefit is the analysis of hydraulic heads and environmental tracers at nested piezometers, or where these are unavailable bore couplets comprising bores above and below the aquitard of interest within a localised geographical area. The proposed methodology has been successful in investigating inter-aquifer leakage in the Arckaringa Basin, South Australia. The suite of environmental tracers and isotopes used to analyse inter-aquifer leakage included the stable isotopes of water, radiocarbon, chloride-36, 87Sr/86Sr and helium isotopes. There is evidence for inter-aquifer leakage in the centre of the basin ~40 km along the regional flow path. This inter-aquifer leakage has been identified by a slight draw-down in the upper aquifer during pumping in the lower aquifer, overlap in Sr isotopes, δ2H, δ18O and chloride

  11. What is the role of wind pumping on heat and mass transfer rates at the air-snow interface?

    NASA Astrophysics Data System (ADS)

    Helgason, W.; Pomeroy, J. W.

    2010-12-01

    Accurate prediction of the turbulent exchange of sensible heat and water vapour between the atmosphere and snowpack remains a challenging task under all but the most ideal conditions. Heat and mass transfer coefficients that recognize the unique properties of the snow surface are warranted. A particular area requiring improvement concerns the role of the porous nature of snow which provides a large surface area for heat and mass exchange with the atmosphere. Wind-pumping has long been considered as a viable mechanism for incorporating aerosols into snowpacks; however these processes are not considered in parameterization schemes for heat and mass transfer near the surface. This study attempts to determine the degree to which wind pumping can increase the rates of heat and mass transfer to snow, and to ascertain which structural properties of the snowpack are needed for inclusion in heat and mass transfer coefficients that reflect wind pumping processes. Based upon a review of recent geophysical and engineering literature where porous surfaces are exploited for their ability to augment heat and mass transfer rates, a technical analysis was conducted. Numerous conceptual mechanisms of wind pumping were considered: topographically-induced flow; barometric pressure changes; high frequency pressure fluctuations at the surface; and steady flow in the interfacial region. A sensitivity analysis was performed, subjecting each conceptual model to varying thermal and hydraulic conditions at the air-snow interface, as well as variable micro-structural properties of snow. It is shown that the rate of heat and mass exchange is most sensitive to the interfacial thermal conditions and factors controlling the energy balance of the uppermost snow grains. The effect upon the thermal regime of the snowpack was found to be most significant for mechanisms of wind pumping that result in shorter flow paths near the surface, rather than those caused by low frequency pressure changes. In

  12. Development of mainshaft seals for advanced air breathing propulsion systems

    NASA Technical Reports Server (NTRS)

    Dobek, L. J.

    1973-01-01

    A gas-film face seal design incorporating shrouded Rayleigh step lift pads at the primary sealing face was analyzed for performance over a wide range of gas turbine engine conditions. Acceptable leakage rates and operation without rubbing contact was predicted for engine conditions that included sealed pressures to 500 psi, sliding speeds to 600 ft/sec, and sealed gas temperatures to 1200 F. In the experimental evaluation, measured gas leakage rates were, in general, close to that predicted and sometimes lower. Satisfactory performance of the gas-film seal was demonstrated at the maximum seal seat axial runout expected in present positive contact face seal applications. Stable operation was shown when testing was performed with air-entrained dirt.

  13. Technology Solutions Case Study: Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

    SciTech Connect

    A. Rudd and D. Bergey

    2015-08-01

    Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs.

  14. Rate-ratio asymptotic analysis of methane-air diffusion-flame structure for predicting production of oxides of nitrogen

    SciTech Connect

    Hewson, J.C.; Williams, F.A.

    1999-05-01

    Production rates of oxides of nitrogen in laminar methane-air diffusion flames are addressed, with thermal, prompt, and nitrous oxide mechanisms taken into account, as well as consumption processes collectively termed reburn. For this purpose, it is necessary to extend the well-known four-step flame-chemistry description to six steps, with acetylene taken out of steady-state and one-step production of nitric oxide included. Emission indices are calculated as functions of the rate of scalar dissipation at the stoichiometric mixture fraction for near-atmospheric pressures and shown to be in reasonable agreement with results obtained from numerical integrations. The various mechanisms of NO{sub x} production and consumption are verified to be strongly dependent on the flame temperature and on superequilibrium concentrations of radicals, both fuel-derived and from hydrogen-oxygen chemistry; the flame-structure analysis was extended to provide sufficient accuracy in the prediction of these quantities. It was found that for flames in near-normal ambient atmospheres, the prompt mechanism usually is most important. For longer residence times, and especially for ambient pressures and temperatures above standard, the thermal mechanism was found to increase in importance, but this increase was calculated to be offset almost entirely by NO consumption through reburn reactions. Conditions that favor reburn were observed to be those where the ratio of radical concentrations to NO concentrations is small. Longer residence times and higher pressures were demonstrated to lead both to more complete heat release and to smaller superequilibrium radical concentrations whence the correspondence between thermal production and reburn. The nitrous oxide mechanism was found to be generally less important for the conditions considered here.

  15. Air Tightness of US Homes: Model Development

    SciTech Connect

    Sherman, Max H.

    2006-05-01

    Air tightness is an important property of building envelopes. It is a key factor in determining infiltration and related wall-performance properties such as indoor air quality, maintainability and moisture balance. Air leakage in U.S. houses consumes roughly 1/3 of the HVAC energy but provides most of the ventilation used to control IAQ. The Lawrence Berkeley National Laboratory has been gathering residential air leakage data from many sources and now has a database of more than 100,000 raw measurements. This paper uses that database to develop a model for estimating air leakage as a function of climate, building age, floor area, building height, floor type, energy-efficiency and low-income designations. The model developed can be used to estimate the leakage distribution of populations of houses.

  16. Imaging inflammatory plasma leakage in vivo.

    PubMed

    Kenne, E; Lindbom, L

    2011-05-01

    Increased vascular permeability and consequent plasma leakage from postcapillary venules is a cardinal sign of inflammation. Although the movement of plasma constituents from the vasculature to the affected tissue aids in clearing the inflammatory stimulus, excessive plasma extravasation can lead to hospitalisation or death in cases such as influenza-induced pneumonia, burns or brain injury. The use of intravital imaging has significantly contributed to the understanding of the mechanisms controlling the vascular permeability alterations that occur during inflammation. Today, intravital imaging can be performed using optical and non-optical techniques. Optical techniques, which are generally used in experimental settings, include traditional intravital fluorescence microscopy and near-infrared fluorescence imaging. Magnetic resonance (MRI) and radioisotopic imaging are used mainly in the clinical setting, but are increasingly used in experimental work, and can detect plasma leakage without optics. Although these methods are all able to visualise inflammatory plasma leakage in vivo, the spatial and temporal resolution differs between the techniques. In addition, they vary with regards to invasiveness and availability. This overview discusses the use of imaging techniques in the visualisation of inflammatory plasma leakage. PMID:21437352

  17. 49 CFR 230.78 - Leakage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... of 3 psi per minute in a test of 3 minutes duration that is made after the pressure has been reduced to 60 percent of the maximum operating pressure. (b) Brake cylinders. Leakage from brake cylinders... pipe pressure, and with communication to the brake cylinders closed, the brakes on the steam...

  18. 49 CFR 230.78 - Leakage.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... of 3 psi per minute in a test of 3 minutes duration that is made after the pressure has been reduced to 60 percent of the maximum operating pressure. (b) Brake cylinders. Leakage from brake cylinders... pipe pressure, and with communication to the brake cylinders closed, the brakes on the steam...

  19. The concept of leakage in threat assessment.

    PubMed

    Meloy, J Reid; O'Toole, Mary Ellen

    2011-01-01

    Leakage in the context of threat assessment is the communication to a third party of an intent to do harm to a target. Third parties are usually other people, but the means of communication vary, and include letters, diaries, journals, blogs, videos on the internet, emails, voice mails, and other social media forms of transmission. Leakage is a type of warning behavior that typically infers a preoccupation with the target, and may signal the research, planning, and implementation of an attack. Nomothetic data suggest that leakage occurs in a majority of cases of attacks on and assassinations of public figures, adult mass murders, adolescent mass murders, and school or campus shootings: very low-frequency, but catastrophic acts of intended and targeted violence. Idiographic or case data illustrate the various permutations of leakage. We discuss the operational importance of the concept, place it in the context of other warning behaviors, emphasize the need for further research, and outline risk management strategies for the mitigation of such acts of violence in both law enforcement and clinical mental health settings. PMID:21710573

  20. SU-E-P-15: Technique Factor Modulation and Reference Plane Air Kerma Rates in Response to Simulated Patient Thickness Variations for a Sample of Current Generation Fluoroscopes

    SciTech Connect

    Wunderle, K; Rakowski, J; Dong, F

    2015-06-15

    Purpose: To evaluate and compare approaches to technique factor modulation and air kerma rates in response to simulated patient thickness variations for four state-of-the-art and one previous-generation interventional fluoroscopes. Methods: A polymethyl methacrylate (PMMA) phantom was used as a tissue surrogate for the purposes of determining fluoroscopic reference plane air kerma rates, kVp, mA, and spectral filtration over a wide range of simulated tissue thicknesses. Data were acquired for each fluoroscopic and acquisition dose curve within a default abdomen or body imaging protocol. Results: The data obtained indicated vendor- and model-specific variations in the approach to technique factor modulation and reference plane air kerma rates across a range of tissue thicknesses. Some vendors have made hardware advances increasing the radiation output capabilities of their fluoroscopes; this was evident in the acquisition air kerma rates. However, in the imaging protocol evaluated, all of the state-of-the-art systems had relatively low air kerma rates in the fluoroscopic low-dose imaging mode as compared to the previous-generation unit. Each of the newest-generation systems also employ copper filtration in the selected protocol in the acquisition mode of imaging; this is a substantial benefit, reducing the skin entrance dose to the patient in the highest dose-rate mode of fluoroscope operation. Conclusion: Understanding how fluoroscopic technique factors are modulated provides insight into the vendor-specific image acquisition approach and provides opportunities to optimize the imaging protocols for clinical practice. The enhanced radiation output capabilities of some of the fluoroscopes may, under specific conditions, may be beneficial; however, these higher output capabilities also have the potential to lead to unnecessarily high dose rates. Therefore, all parties involved in imaging, including the clinical team, medical physicists, and imaging vendors, must work

  1. An Advanced Leakage Scheme for Neutrino Treatment in Astrophysical Simulations

    NASA Astrophysics Data System (ADS)

    Perego, A.; Cabezón, R. M.; Käppeli, R.

    2016-04-01

    We present an Advanced Spectral Leakage (ASL) scheme to model neutrinos in the context of core-collapse supernovae (CCSNe) and compact binary mergers. Based on previous gray leakage schemes, the ASL scheme computes the neutrino cooling rates by interpolating local production and diffusion rates (relevant in optically thin and thick regimes, respectively) separately for discretized values of the neutrino energy. Neutrino trapped components are also modeled, based on equilibrium and timescale arguments. The better accuracy achieved by the spectral treatment allows a more reliable computation of neutrino heating rates in optically thin conditions. The scheme has been calibrated and tested against Boltzmann transport in the context of Newtonian spherically symmetric models of CCSNe. ASL shows a very good qualitative and a partial quantitative agreement for key quantities from collapse to a few hundreds of milliseconds after core bounce. We have proved the adaptability and flexibility of our ASL scheme, coupling it to an axisymmetric Eulerian and to a three-dimensional smoothed particle hydrodynamics code to simulate core collapse. Therefore, the neutrino treatment presented here is ideal for large parameter-space explorations, parametric studies, high-resolution tests, code developments, and long-term modeling of asymmetric configurations, where more detailed neutrino treatments are not available or are currently computationally too expensive.

  2. EVALUATION OF LEAKAGE FROM FUME HOODS USING TRACER GAS, TRACER NANOPARTICLES AND NANOPOWDER HANDLING TEST METHODOLOGIES

    PubMed Central

    Dunn, Kevin H.; Tsai, Candace Su-Jung; Woskie, Susan R.; Bennett, James S.; Garcia, Alberto; Ellenbecker, Michael J.

    2015-01-01

    The most commonly reported control used to minimize workplace exposures to nanomaterials is the chemical fume hood. Studies have shown, however, that significant releases of nanoparticles can occur when materials are handled inside fume hoods. This study evaluated the performance of a new commercially available nano fume hood using three different test protocols. Tracer gas, tracer nanoparticle, and nanopowder handling protocols were used to evaluate the hood. A static test procedure using tracer gas (sulfur hexafluoride) and nanoparticles as well as an active test using an operator handling nanoalumina were conducted. A commercially available particle generator was used to produce sodium chloride tracer nanoparticles. Containment effectiveness was evaluated by sampling both in the breathing zone (BZ) of a mannequin and operator as well as across the hood opening. These containment tests were conducted across a range of hood face velocities (60, 80, and 100 feet/minute) and with the room ventilation system turned off and on. For the tracer gas and tracer nanoparticle tests, leakage was much more prominent on the left side of the hood (closest to the room supply air diffuser) although some leakage was noted on the right side and in the BZ sample locations. During the tracer gas and tracer nanoparticle tests, leakage was primarily noted when the room air conditioner was on for both the low and medium hood exhaust air flows. When the room air conditioner was turned off, the static tracer gas tests showed good containment across most test conditions. The tracer gas and nanoparticle test results were well correlated showing hood leakage under the same conditions and at the same sample locations. The impact of a room air conditioner was demonstrated with containment being adversely impacted during the use of room air ventilation. The tracer nanoparticle approach is a simple method requiring minimal setup and instrumentation. However, the method requires the reduction in

  3. The application of FLUENT in simulating outcomes from chlorine leakage accidents in a typical chemical factory.

    PubMed

    Li, Jianfeng; Zhang, Bin; Tang, Sichuang; Tong, Ruipeng

    2016-05-01

    For improvements in market competitiveness, old brand chemical enterprises did some expansion and reconstruction on the base of original equipment. Because it is the reconstruction on the basis of the existing production equipment, it is bound to raise problems of reutilization existing in pipelines and equipment. A simplified typical chemical factory was established referring the actual workshop layout. Further, trustable accident scenarios were conducted to reveal the diffusion process. In a larger leakage rate, the chlorine leak-affected area in the downwind became larger a bit, also in a relatively shorter time, lethal scope will become larger quickly, resulting in more threats to the lives and properties in the vicinity of the factories. Further, it is not possible that the heavier-than-air effect of the chlorine will inevitably result in a higher concentration for a lower surface than that of higher surface. Actually at a certain height, a relatively higher monitoring surface has a larger diffusion range and a larger concentration than a relatively lower surface. It can be inferred that within a certain height, chlorine diffusion rate closer to the ground would be slower due to existence of turbulence or the relative resistance on the ground. PMID:24442346

  4. Hydrocarbons Emissions Due to Wellbore and other Subsurface Leakage in the Uintah Basin, Utah

    NASA Astrophysics Data System (ADS)

    Watkins, C.; Lyman, S. N.

    2015-12-01

    The explosive growth of oil and gas production in the United States has focused public and regulatory attention on environmental impacts of hydrocarbon extraction, including air quality and climate impacts. One potentially important emissions source is subsurface leakage of natural gas. Better understanding of wellbore and other subsurface leaks are important in providing ways to decrease pollution while increasing the efficiency of oil and gas production. Soil gas measurements carried out by USGS over the last several years in Utah's oil and gas fields have shown that, while concentrations of methane in soils near wells are typically low, soil gas near some wells can contain more than 50% methane. In the summers of 2013-2015 we carried out campaigns to measure the emission rate of methane and other hydrocarbons from soils near wells in the Uintah Basin, Utah. We also measured emissions at several locations on individual well pads and determined that concentrations of hydrocarbons tend to decrease with distance from the well head. Soil emissions were also measured at non-well sites in the same area to determine background emission rates. Emissions from exposed coal, oil shale, gilsonite, and fault zone surfaces were also measured. Relationships of emissions with soil gas concentrations, meteorological conditions, and soil properties were also investigated.

  5. Pipeline leakage detection using distributed fibre optical temperature sensing

    NASA Astrophysics Data System (ADS)

    Grosswig, S.; Hurtig, E.; Luebbecke, S.; Vogel, B.

    2005-05-01

    The leakage detection system based on the distributed fibre optical temperature measurement method is an analysing method for continuous detection and localization of leakages at pipelines in the steady and unsteady operation states according to the German rules for pipelines TRbF 301/TRFL which is valid in Germany since April 2003. The leakage detection system is useable under the precondition that there is a sufficient large temperature gradient between the leakage area and the unaffected environment. This can be caused by the medium itself or through a physical effect due to the leakage, e.g. gas expansion, evaporation. It's a very sensitive method, so also creeping leakages can be detected.

  6. Traffic-Related Air Pollution and Acute Changes in Heart Rate Variability and Respiratory Function in Urban Cyclists

    PubMed Central

    Kulka, Ryan; Dubeau, Aimee; Martin, Christina; Wang, Daniel; Dales, Robert

    2011-01-01

    Background: Few studies have examined the acute health effects of air pollution exposures experienced while cycling in traffic. Objectives: We conducted a crossover study to examine the relationship between traffic pollution and acute changes in heart rate variability. We also collected spirometry and exhaled nitric oxide measures. Methods: Forty-two healthy adults cycled for 1 hr on high- and low-traffic routes as well as indoors. Health measures were collected before cycling and 1–4 hr after the start of cycling. Ultrafine particles (UFPs; ≤ 0.1 μm in aerodynamic diameter), particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5), black carbon, and volatile organic compounds were measured along each cycling route, and ambient nitrogen dioxide (NO2) and ozone (O3) levels were recorded from a fixed-site monitor. Mixed-effects models were used to estimate associations between air pollutants and changes in health outcome measures relative to precycling baseline values. Results: An interquartile range increase in UFP levels (18,200/cm3) was associated with a significant decrease in high-frequency power 4 hr after the start of cycling [β = –224 msec2; 95% confidence interval (CI), –386 to –63 msec2]. Ambient NO2 levels were inversely associated with the standard deviation of normal-to-normal (NN) intervals (β = –10 msec; 95% CI, –20 to –0.34 msec) and positively associated with the ratio of low-frequency to high-frequency power (β = 1.4; 95% CI, 0.35 to 2.5) 2 hr after the start of cycling. We also observed significant inverse associations between ambient O3 levels and the root mean square of successive differences in adjacent NN intervals 3 hr after the start of cycling. Conclusions: Short-term exposures to traffic pollution may contribute to altered autonomic modulation of the heart in the hours immediately after cycling. PMID:21672679

  7. Effects of H2O, CO2, and N2 Air Contaminants on Critical Airside Strain Rates for Extinction of Hydrogen-Air Counterflow Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Pellett, G. L.; Wilson, L. G.; Northam, G. B.; Guerra, Rosemary

    1989-01-01

    Coaxial tubular opposed jet burners (OJB) were used to form dish shaped counterflow diffusion flames (CFDF), centered by opposing laminar jets of H2, N2 and both clean and contaminated air (O2/N2 mixtures) in an argon bath at 1 atm. Jet velocities for flame extinction and restoration limits are shown versus wide ranges of contaminant and O2 concentrations in the air jet, and also input H2 concentration. Blowoff, a sudden breaking of CFDF to a stable ring shape, occurs in highly stretched stagnation flows and is generally believed to measure kinetically limited flame reactivity. Restore, a sudden restoration of central flame, is a relatively new phenomenon which exhibits a H2 dependent hysteresis from Blowoff. For 25 percent O2 air mixtures, mole for mole replacement of 25 percent N2 contaminant by steam increased U(air) or flame strength at Blowoff by about 5 percent. This result is consistent with laminar burning velocity results from analogous substitution of steam for N2 in a premixed stoichiometric H2-O2-N2 (or steam) flame, shown by Koroll and Mulpuru to promote a 10 percent increase in experimental and calculated laminar burning velocity, due to enhanced third body efficiency of water in: H + O2 + M yields HO2 + M. When the OJB results were compared with Liu and MacFarlane's experimental laminar burning velocity of premixed stoichiometric H2 + air + steam, a crossover occurred, i.e., steam enhanced OJB flame strength at extinction relative to laminar burning velocity.

  8. Heating rate measurements over 30 deg and 40 deg (half angle) blunt cones in air and helium in the Langley expansion tube facility

    NASA Technical Reports Server (NTRS)

    Reddy, N. M.

    1980-01-01

    Convective heat transfer measurements, made on the conical portion of spherically blunted cones (30 deg and 40 deg half angle) in an expansion tube are discussed. The test gases used were helium and air; flow velocities were about 6.8 km/sec for helium and about 5.1 km/sec for air. The measured heating rates are compared with calculated results using a viscous shock layer computer code. For air, various techniques to determine flow velocity yielded identical results, but for helium, the flow velocity varied by as much as eight percent depending on which technique was used. The measured heating rates are in satisfactory agreement with calculation for helium, assuming the lower flow velocity, the measurements are significantly greater than theory and the discrepancy increased with increasing distance along the cone.

  9. Structural and leakage integrity of tubes affected by circumferential cracking

    SciTech Connect

    Hernalsteen, P.

    1997-02-01

    In this paper the author deals with the notion that circumferential cracks are generally considered unacceptable. He argues for the need to differentiate two facets of such cracks: the issue of the size and growth rate of a crack; and the issue of the structural strength and leakage potential of the tube in the presence of the crack. In this paper the author tries to show that the second point is not a major concern for such cracks. The paper presents data on the structural strength or burst pressure characteristics of steam generator tubes derived from models and data bases of experimental work. He also presents a leak rate model, and compares the performance of circumferential and axial cracks as far as burst strength and leak rate. The final conclusion is that subject to improvement in NDE capabilities (sizing, detection, growth), that Steam Generator Defect Specific Management can be used to allow circumferentially degraded tubes to remain in service.

  10. QUALITY ASSURANCE PROCEDURES: METHOD 28A MEASUREMENT OF AIR TO FUEL RATIO AND MINIMUM BURN RATE FOR WOOD-FIRED APPLIANCES

    EPA Science Inventory

    Quality assurance procedures are contained in this comprehensive document intended to be used as an aid for wood heater manufacturers and testing laboratories in performing measurement of air-to-fuel ratio and minimum burn rate determinations according to EPA protocol, Method 28A...

  11. Effect of air flow rate on the polyphenols content and antioxidant capacity of convective dried cactus pear cladodes (Opuntia ficus indica).

    PubMed

    Gallegos-Infante, José-Alberto; Rocha-Guzman, Nuria-Elizabeth; González-Laredo, Ruben-Francisco; Reynoso-Camacho, Rosalia; Medina-Torres, Luis; Cervantes-Cardozo, Veronica

    2009-01-01

    The interest in nopal has encouraged the use of dehydration; there are few studies about the effect of process parameters on the nopal polyphenol content and antioxidant activity. The objective of the present work was to evaluate the effect of air-drying flow rates on the amount and antioxidant capacity of extracts of Opuntia ficus indica cladodes. Nopal was dried at 45 degrees C and air flow rates of 3 and 5 m/sec. Samples were analyzed for moisture, total polyphenol, flavonoid, and flavonol contents, chain-breaking activity, inhibition of low-density lipoprotein and deoxyribose oxidation. Nopal drying at an air flow rate of 3 m/sec showed higher values of phenols, flavonoids and flavonols. The best value of low-density lipoprotein inhibition and deoxyribose was found at 1,000 microg/ml. The air flow rate affected the amount of polyphenols and the OH( . ) radical scavenging, but did not modify the chain-breaking activity and the low-density lipoprotein inhibition activity. PMID:19468951

  12. Association of Heart Rate Variability in Taxi Drivers with Marked Changes in Particulate Air Pollution in Beijing in 2008

    PubMed Central

    Wu, Shaowei; Deng, Furong; Niu, Jie; Huang, Qinsheng; Liu, Youcheng; Guo, Xinbiao

    2010-01-01

    Background Heart rate variability (HRV), a marker of cardiac autonomic function, has been associated with particulate matter (PM) air pollution, especially in older patients and those with cardiovascular diseases. However, the effect of PM exposure on cardiac autonomic function in young, healthy adults has received less attention. Objectives We evaluated the relationship between exposure to traffic-related PM with an aerodynamic diameter ≤ 2.5 μm (PM2.5) and HRV in a highly exposed panel of taxi drivers. Methods Continuous measurements of personal exposure to PM2.5 and ambulatory electrocardiogram monitoring were conducted on 11 young healthy taxi drivers for a 12-hr work shift during their work time (0900–2100 hr) before, during, and after the Beijing 2008 Olympic Games. Mixed-effects regression models were used to estimate associations between PM2.5 exposure and percent changes in 5-min HRV indices after combining data from the three time periods and controlling for potentially confounding variables. Results Personal exposures of taxi drivers to PM2.5 changed markedly across the three time periods. The standard deviation of normal-to-normal (SDNN) intervals decreased by 2.2% [95% confidence interval (CI), −3.8% to −0.6%] with an interquartile range (IQR; 69.5 μg/m3) increase in the 30-min PM2.5 moving average, whereas the low-frequency and high-frequency powers decreased by 4.2% (95% CI, −9.0% to 0.8%) and 6.2% (95% CI, −10.7% to −1.5%), respectively, in association with an IQR increase in the 2-hr PM2.5 moving average. Conclusions Marked changes in traffic-related PM2.5 exposure were associated with altered cardiac autonomic function in young healthy adults. PMID:20056565

  13. Engine panel seals for hypersonic engine applications: High temperature leakage assessments and flow modelling

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M.; Mutharasan, Rajakkannu; Du, Guang-Wu; Miller, Jeffrey H.; Ko, Frank

    1992-01-01

    A critical mechanical system in advanced hypersonic engines is the panel-edge seal system that seals gaps between the articulating horizontal engine panels and the adjacent engine splitter walls. Significant advancements in seal technology are required to meet the extreme demands placed on the seals, including the simultaneous requirements of low leakage, conformable, high temperature, high pressure, sliding operation. In this investigation, the seal concept design and development of two new seal classes that show promise of meeting these demands will be presented. These seals include the ceramic wafer seal and the braided ceramic rope seal. Presented are key elements of leakage flow models for each of these seal types. Flow models such as these help designers to predict performance-robbing parasitic losses past the seals, and estimate purge coolant flow rates. Comparisons are made between measured and predicted leakage rates over a wide range of engine simulated temperatures and pressures, showing good agreement.

  14. Trending of Overboard Leakage of ISS Cabin Atmosphere

    NASA Technical Reports Server (NTRS)

    Schaezler, Ryan N.; Cook, Anthony J.; Leonard, Daniel J.; Ghariani, Ahmed

    2011-01-01

    The International Space Station (ISS) overboard leakage of cabin atmosphere is continually tracked to identify new or aggravated leaks and to provide information for planning of nitrogen supply to the ISS. The overboard leakage is difficult to trend with various atmosphere constituents being added and removed. Changes to nitrogen partial pressure is the nominal means of trending the overboard leakage. This paper summarizes the method of the overboard leakage trending and presents findings from the trending.

  15. Air Change Rates and Interzonal Flows in Residences, and the Need for Multi-Zone Models for Exposure and Health Analyses

    PubMed Central

    Du, Liuliu; Batterman, Stuart; Godwin, Christopher; Chin, Jo-Yu; Parker, Edith; Breen, Michael; Brakefield, Wilma; Robins, Thomas; Lewis, Toby

    2012-01-01

    Air change rates (ACRs) and interzonal flows are key determinants of indoor air quality (IAQ) and building energy use. This paper characterizes ACRs and interzonal flows in 126 houses, and evaluates effects of these parameters on IAQ. ACRs measured using weeklong tracer measurements in several seasons averaged 0.73 ± 0.76 h−1 (median = 0.57 h−1, n = 263) in the general living area, and much higher, 1.66 ± 1.50 h−1 (median = 1.23 h−1, n = 253) in bedrooms. Living area ACRs were highest in winter and lowest in spring; bedroom ACRs were highest in summer and lowest in spring. Bedrooms received an average of 55 ± 18% of air from elsewhere in the house; the living area received only 26 ± 20% from the bedroom. Interzonal flows did not depend on season, indoor smoking or the presence of air conditioners. A two-zone IAQ model calibrated for the field study showed large differences in pollutant levels between the living area and bedroom, and the key parameters affecting IAQ were emission rates, emission source locations, air filter use, ACRs, interzonal flows, outdoor concentrations, and PM penetration factors. The single-zone models that are commonly used for residences have substantial limitations and may inadequately represent pollutant concentrations and exposures in bedrooms and potentially other environments other where people spend a substantial fraction of time. PMID:23235286

  16. Anastomotic leakage after anterior resection for rectal cancer with mesorectal excision: incidence, risk factors, and management.

    PubMed

    Tortorelli, Antonio Pio; Alfieri, Sergio; Sanchez, Alejandro Martin; Rosa, Fausto; Papa, Valerio; Di Miceli, Dario; Bellantone, Chiara; Doglietto, Giovanni Battista

    2015-01-01

    We investigated risk factors and prognostic implications of symptomatic anastomotic leakage after anterior resection for rectal cancer, and the influence of a diverting stoma. Our retrospective review of prospective collected data analyzed 475 patients who underwent anterior resection for rectal cancer. Uni- and multivariate analysis was made between anastomotic leakage and patient, tumor, and treatment variables, either for the overall group (n = 475) and in the midlow rectal cancer subgroup (n = 291). Overall rate of symptomatic leakage was 9 per cent (43 of 475) with no related postoperative mortality. At univariate analysis, significant factors for leak were a tumor less than 6 cm from the anal verge (13.7 vs 6.6%; P = 0.011) and intraoperative transfusions (16.9 vs 4.3%; P = 0.001). Similar results were observed in the midlow rectal cancer subgroup. At multivariate analysis, no parameter resulted in being an independent prognostic factor for risk of leakage. In patients with a leakage, a temporary enterostomy considerably reduced the need for reoperation (12.5 vs 77.8%; P < 0.0001) and the risk of a permanent stoma (18.7 vs 28.5%; P = 0.49). The incidence of anastomotic failure increases for lower tumors, whereas it is not influenced by radiotherapy. Defunctioning enterostomy does not influence the leak rate, but it mitigates clinical consequences. PMID:25569064

  17. Radiation induced inter-device leakage degradation

    NASA Astrophysics Data System (ADS)

    Hu, Zhi-Yuan; Liu, Zhang-Li; Shao, Hua; Zhang, Zheng-Xuan; Ning, Bing-Xu; Chen, Ming; Bi, Da-Wei; Zou, Shi-Chang

    2011-08-01

    The evolution of inter-device leakage current with total ionizing dose in transistors in 180 nm generation technologies is studied with an N-type poly-gate field device (PFD) that uses the shallow trench isolation as an effective gate oxide. The overall radiation response of these structures is determined by the trapped charge in the oxide. The impacts of different bias conditions during irradiation on the inter-device leakage current are studied for the first time in this work, which demonstrates that the worst condition is the same as traditional NMOS transistors. Moreover, the two-dimensional technology computer-aided design simulation is used to understand the bias dependence.

  18. 42 CFR 84.92 - Exhalation valve leakage test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Exhalation valve leakage test. 84.92 Section 84.92... Breathing Apparatus § 84.92 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be...) Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute....

  19. 42 CFR 84.92 - Exhalation valve leakage test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Exhalation valve leakage test. 84.92 Section 84.92... Breathing Apparatus § 84.92 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be...) Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute....

  20. 42 CFR 84.92 - Exhalation valve leakage test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Exhalation valve leakage test. 84.92 Section 84.92... Breathing Apparatus § 84.92 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be...) Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute....

  1. 42 CFR 84.92 - Exhalation valve leakage test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Exhalation valve leakage test. 84.92 Section 84.92... Breathing Apparatus § 84.92 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be...) Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute....

  2. 42 CFR 84.92 - Exhalation valve leakage test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Exhalation valve leakage test. 84.92 Section 84.92... Breathing Apparatus § 84.92 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be...) Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute....

  3. 49 CFR 192.706 - Transmission lines: Leakage surveys.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Transmission lines: Leakage surveys. 192.706... Transmission lines: Leakage surveys. Leakage surveys of a transmission line must be conducted at intervals not exceeding 15 months, but at least once each calendar year. However, in the case of a transmission line...

  4. 49 CFR 192.706 - Transmission lines: Leakage surveys.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Transmission lines: Leakage surveys. 192.706... Transmission lines: Leakage surveys. Leakage surveys of a transmission line must be conducted at intervals not exceeding 15 months, but at least once each calendar year. However, in the case of a transmission line...

  5. 49 CFR 192.706 - Transmission lines: Leakage surveys.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  6. 49 CFR 192.706 - Transmission lines: Leakage surveys.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Transmission lines: Leakage surveys. 192.706... Transmission lines: Leakage surveys. Leakage surveys of a transmission line must be conducted at intervals not exceeding 15 months, but at least once each calendar year. However, in the case of a transmission line...

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

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Transmission lines: Leakage surveys. 192.706... Transmission lines: Leakage surveys. Leakage surveys of a transmission line must be conducted at intervals not exceeding 15 months, but at least once each calendar year. However, in the case of a transmission line...

  8. 3DHZETRN: Neutron leakage in finite objects

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  9. 3DHZETRN: Neutron leakage in finite objects.

    PubMed

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

    2015-11-01

    The 3DHZETRN formalism was recently developed as an extension to HZETRN with an emphasis on 3D corrections for neutrons and light ions. Comparisons to Monte Carlo (MC) simulations were used to verify the 3DHZETRN methodology in slab and spherical geometry, and it was shown that 3DHZETRN agrees with MC codes to the degree that various MC codes agree among themselves. One limitation of such comparisons is that all of the codes (3DHZETRN and three MC codes) utilize different nuclear models/databases; additionally, using a common nuclear model is impractical due to the complexity of the software. It is therefore difficult to ascertain if observed discrepancies are caused by transport code approximations or nuclear model differences. In particular, an important simplification in the 3DHZETRN formalism assumes that neutron production cross sections can be represented as the sum of forward and isotropic components, where the forward component is subsequently solved within the straight-ahead approximation. In the present report, previous transport model results in specific geometries are combined with additional results in related geometries to study neutron leakage using the Webber 1956 solar particle event as a source boundary condition. A ratio is defined to quantify the fractional neutron leakage at a point in a finite object relative to a semi-infinite slab geometry. Using the leakage ratio removes some of the dependence on the magnitude of the neutron production and clarifies the effects of angular scattering and absorption with regard to differences between the models. Discussion is given regarding observed differences between the MC codes and conclusions drawn about the need for further code development. Although the current version of 3DHZETRN is reasonably accurate compared to MC simulations, this study shows that improved leakage estimates can be obtained by replacing the isotropic/straight-ahead approximation with more detailed descriptions. PMID:26553635

  10. Remote Sensing And Surface Hydrocarbon Leakage

    NASA Astrophysics Data System (ADS)

    Matthews, M. D.; Jones, V. T.; Richers, D. M.

    1984-08-01

    The Geosat oil and gas test site program stimulated interest in the interaction between surface hydrocarbon concentrations and interpretation of remote sensing data. The test case results suggested that lineaments correspond to avenues of preferential hydrocarbon seepage and that this seepage affects vegetation health and populations at Patrick Draw field in Wyoming and potentially at Lost River field, West Virginia. These two areas were selected for additional surface hydrocarbon surveys in order to test these hypotheses. The Patrick Draw study shows that a zone of stressed vegetation, visible on thematic mapper data, definitely coincides with an area of marked leakage of hydrocarbons and that the composition of these gases would predict an intermediate type oil and gas reservoir such as exists in the area. The study further indicates that the leakage is in large part controlled by the presence of fractures/faults recognized as lineaments on the remote sensing images. The Lost River study specifically investigated the possible existence of hydrocarbon leakage causing anomalous populations of maple trees in a climax oak forest. These maples were first recognized by study of thematic mapper simulator data. The soil gas hydrocarbon concentrations are above average in several of the maple anomalies over the field. This supports the inference that the maples are present because they are more tolerant of soil conditions where hydrocarbon seepage is active. The crest of the field has low soil gas magnitudes, but high values occur to the updip eastern edge of the field along a fault/fracture that was detected in the seismic data. The conclusion that preferential pathways of hydrocarbon leakage are recognized in spectral and textural analysis of remote sensing data is supported by other studies and integrated into a suggested exploration/hydrocarbon migration model.

  11. Effects of H2O, CO2, and N2 air contaminants on critical airside strain rates for extinction of hydrogen-air counterflow diffusion flames

    NASA Technical Reports Server (NTRS)

    Pellett, G. L.; Northam, G. B.; Wilson, L. G.; Guerra, Rosemary

    1989-01-01

    Dish-shaped counterflow diffusion flames centered by opposing laminar jets of H2 and clean and contaminant O2/N2 mixtures in an argon bath at 1 atm were used to study the effects of contaminants on critical airside strain. The jet velocities for both flame extinction and restoration are found for a wide range of contaminant and O2 concentrations in the air jet. The tests are also conducted for a variety of input H2 concentrations. The results are compared with those from several other studies.

  12. Counterflow diffusion flames of hydrogen, and hydrogen plus methane, ethylene, propane, and silane vs. air - Strain rates at extinction

    NASA Technical Reports Server (NTRS)

    Pellett, G. L.; Northam, G. Burton; Wilson, L. G.

    1991-01-01

    Five coaxial tubular opposed jet burners (OJBs) with tube diameter D(T) of 1.8-10 mm and 5 mm conical nozzles were used to form dish-shaped counterflow diffusion flames centered by opposing laminar jets of nitrogen and hydrocarbon-diluted H2 versus air in an argon-purged chamber at 1 atm. Area-averaged air jet velocities at blowoff of the central flame, U(air), characterized extinction of the airside flame as functions of input H2 concentration on the fuelside. A master plot of extensive U(air) data at blowoff versus D(T) shows that U(air) varies linearly with D(T). This and other data sets are used to find that nozzle OJB results for U(air)/diameter average 4.24 + or - 0.28 times larger than tubular OJB results for the same fuel compositions. Critical radial velocity gradients consistent with one-dimensional stagnation point boundary theory and with plug flow inputs are estimated. The results compare favorably with published numerical results based only on potential flow.

  13. Atomic Oxygen Effects on Seal Leakage

    NASA Technical Reports Server (NTRS)

    Christensen, John R.; Underwood, Steve D.; Kamenetzky, Rachel R.; Vaughn, Jason A.

    1999-01-01

    Common Berthing Mechanism (CBM provides the structural interface between separate International Space Station (ISS) elements, such as the Laboratory and Node modules. The CBM consists of an active and a passive half that join together with structural bolts. The seal at this interface is the CBM-to-CBM molded seal. The CBM-to-CBM interface is assembled on orbit, thus the seals can be exposed to the space environment for up to 65 hours. Atomic Oxygen/Vacuum Ultraviolet radiation (AO/VUV) in space is a potential hazard to the seals. Testing was conducted to determine the effect on leakage of the CBM-to-CBM seal material exposed to AO/VUV. The sealing materials were S383 silicone and V835 fluorocarbon material. Control samples, which were not exposed to the AO/VUV environment, were used to ensure that ff any changes in leakage occurred, they could be attributed to the AO/VUV exposure. After exposure to the AO/VUV environment the leakage increase was dramatic for the fluorocarbon. This testing was a major contributing factor in selecting silicone as the CBM-to-CBM seal material.

  14. Time reversal technique for gas leakage detection.

    PubMed

    Maksimov, A O; Polovinka, Yu A

    2015-04-01

    The acoustic remote sensing of subsea gas leakage traditionally uses sonars as active acoustic sensors and hydrophones picking up the sound generated by a leak as passive sensors. When gas leaks occur underwater, bubbles are produced and emit sound at frequencies intimately related to their sizes. The experimental implementation of an acoustic time-reversal mirror (TRM) is now well established in underwater acoustics. In the basic TRM experiment, a probe source emits a pulse that is received on an array of sensors, time reversed, and re-emitted. After time reversal, the resulting field focuses back at the probe position. In this study, a method for enhancing operation of the passive receiving system has been proposed by using it in the regime of TRM. Two factors, the local character of the acoustic emission signal caused by the leakage and a resonant nature of the bubble radiation at their birth, make particularly effective scattering with the conjugate wave (CW). Analytical calculations are performed for the scattering of CW wave on a single bubble when CW is formed by bubble birthing wail received on an array, time reversed, and re-emitted. The quality of leakage detection depends on the spatio-temporal distribution of ambient noise. PMID:25920866

  15. Atomic Oxygen Effects on Seal Leakage

    NASA Technical Reports Server (NTRS)

    Christensen, John R.; Underwood, Steve D.; Kamenetzky, Rachel R.; Vaughn, Jason A.

    1998-01-01

    Common Berthing Mechanism (CBM) provides the structural interface between separate International Space Station (ISS) elements, such as the Laboratory and Node modules. The CBM consists of an active and a passive half that join together with structural bolts. The seal at this interface is the CBM-to-CBM molded seal. The CBM-to-CBM interface is assembled on orbit, thus the seals can be exposed to the space environment for up to 65 hours. Atomic Oxygen/Vacuum Ultraviolet radiation (AO/VUV) in space is a potential hazard to the seals. Testing was conducted to determine the effect on leakage of the CBM-to-CBM seal material exposed to AO/VUV. The sealing materials were S383 silicone and V835 fluorocarbon material. Control samples, which were not exposed to the AO/VUV environment, were used to ensure that if any changes in leakage occurred, they could be attributed to the AO/VUV exposure. After exposure to the AO/VUV environment the leakage increase was dramatic for the fluorocarbon. This testing was a major contributing factor in selecting silicone as the CBM-to-CBM seal material.

  16. Determination of air-kerma strength for the {sup 192}Ir GammaMedplus iX pulsed-dose-rate brachytherapy source

    SciTech Connect

    Riley, A. D.; Pike, T. L.; Micka, J. A.; Fulkerson, R. K.; DeWerd, L. A.

    2013-07-15

    Purpose: Pulsed-dose-rate (PDR) brachytherapy was originally proposed to combine the therapeutic advantages of high-dose-rate (HDR) and low-dose-rate brachytherapy. Though uncommon in the United States, several facilities employ pulsed-dose-rate brachytherapy in Europe and Canada. Currently, there is no air-kerma strength standard for PDR brachytherapy {sup 192}Ir sources traceable to the National Institute of Standards and Technology. Discrepancies in clinical measurements of the air-kerma strength of the PDR brachytherapy sources using HDR source-calibrated well chambers warrant further investigation.Methods: In this research, the air-kerma strength for an {sup 192}Ir PDR brachytherapy source was compared with the University of Wisconsin Accredited Dosimetry Calibration Laboratory transfer standard well chambers, the seven-distance technique [B. E. Rasmussen et al., 'The air-kerma strength standard for 192Ir HDR sources,' Med. Phys. 38, 6721-6729 (2011)], and the manufacturer's stated value. Radiochromic film and Monte Carlo techniques were also employed for comparison to the results of the measurements.Results: While the measurements using the seven-distance technique were within + 0.44% from the manufacturer's determination, there was a + 3.10% difference between the transfer standard well chamber measurements and the manufacturer's stated value. Results showed that the PDR brachytherapy source has geometric and thus radiological qualities that exhibit behaviors similar to a point source model in contrast to a conventional line source model.Conclusions: The resulting effect of the pointlike characteristics of the PDR brachytherapy source likely account for the differences observed between well chamber and in-air measurements.

  17. A Clinical Parameters-Based Model Predicts Anastomotic Leakage After a Laparoscopic Total Mesorectal Excision

    PubMed Central

    Hu, Xiang; Cheng, Yong

    2015-01-01

    Abstract Anastomotic leakage after colorectal surgery is a major and life-threatening complication that occurs more frequently than expected. Intraoperative judgment in predicting potential leakage has shown extremely low sensitivity and specificity. The lack of a model for predicting anastomotic leakage might explain this insufficient judgment. We aimed to propose a clinical parameters-based model to predict anastomotic leakage after laparoscopic total mesorectal excision (TME). This study was a retrospective analysis of a prospectively designed colorectal cancer dataset. In total, 1968 patients with a laparoscopic TME were enrolled from November 1, 2010, to March 20, 2014. The independent risk factors for anastomotic leakage were identified, from which the parameters-based model for leakage was developed. Anastomotic leakage was noted in 63 patients (3.2%). Male sex, a low level of anastomosis, intraoperative blood loss, diabetes, the duration time of the surgery, and low temperature were significantly associated by the bivariate analysis and the Cochran–Mantel–Haenszel test with an increased risk. From these factors, the logistic regression model identified the following 4 independent predictors: male sex (risk ratio [RR] = 1.85, 95% confidence interval [CI]: 1.13–4.87), diabetes (RR = 2.08, 95% CI: 1.19–5.8), a lower anastomosis level (RR = 3.41, 95% CI: 1.17–6.71), and a high volume of blood loss (RR = 1.03, 95% CI: 1.01–1.05). The locally weighted scatterplot smoothing regression showed an anastomosis within 5 cm from the anus and intraoperative blood loss of >100 mL as the cutoff values for a significantly increased risk of leakage. Based on these independent factors, a parameters-based model was established by the regression coefficients. The high and low-risk groups were classified according to scores of 3–5 and 0–2, with leakage rates of 8.57% and 1.66%, respectively (P < 0.001). This parameters-based model could

  18. Heparin Leakage in Central Venous Catheters by Hemodynamic Transport

    NASA Astrophysics Data System (ADS)

    Barbour, Michael; McGah, Patrick; Gow, Kenneth; Aliseda, Alberto

    2014-11-01

    Central venous catheters (CVCs), placed in the superior vena cava for hemodialysis, are routinely filled with heparin, an anticoagulant, while not in use to maintain patency and prevent thrombus formation at the catheter tip. However, the heparin-lock procedure places the patient at risk for systemic bleeding incidences, as heparin is known to leak into the blood stream. We propose that the driving mechanism behind heparin leakage is advective-diffusive transport due to the pulsatile blood flow surrounding the catheter tip. This novel hypothesis is based on Planar Laser Induced Fluorescence (PLIF) measurements of heparin transport from a CVC placed inside an in vitro pulsatile flow loop and validated with CFD simulations. The results show an initial, fast (<10s), advection-dominated phase that rapidly depletes the concentration of heparin at the CVC tip, followed by a slow, diffusion-limited phase inside the catheter lumen, where concentration is still high, that is insufficient at replenishing the lost heparin at the tip. These results, which estimate leakage rates consistent with published in vivo data, predict that the concentration of heparin at the catheter tip is effectively zero for the majority of the interdialytic phase, rendering the heparin lock ineffective.

  19. Antimicrobial Peptide Lactoferricin B-Induced Rapid Leakage of Internal Contents from Single Giant Unilamellar Vesicles.

    PubMed

    Moniruzzaman, Md; Alam, Jahangir Md; Dohra, Hideo; Yamazaki, Masahito

    2015-09-29

    Enzymatic digestion of bovine lactoferrin generates lactoferricin B (Lfcin B), a 25-mer peptide with strong antimicrobial activity of unknown mechanism. To elucidate the mechanistic basis of Lfcin B bactericidal activity, we investigated the interaction of Lfcin B with Escherichia coli and liposomes of lipid membranes. Lfcin B induced the influx of a membrane-impermeant fluorescent probe, SYTOX green, from the outside of E. coli into its cytoplasm. Lfcin B induced gradual leakage of calcein from large unilamellar vesicles (LUVs) of dioleoylphosphatidylglycerol (DOPG)/dioleoylphosphatidylcholine (DOPC) membranes. To clarify the cause of Lfcin B-induced leakage of calcein from the LUVs, we used the single giant unilamellar vesicle (GUV) method to investigate the interaction of Lfcin B with calcein-containing DOPG/DOPC-GUVs. We observed that a rapid leakage of calcein from a GUV started stochastically; statistical analysis provided a rate constant for Lfcin B-induced pore formation, kp. On the other hand, phase-contrast microscopic images revealed that Lfcin B induced a rapid leakage of sucrose from the single GUVs with concomitant appearance of a spherical GUV of smaller diameter. Because of the very fast leakage, and at the present time resolution of the experiments (33 ms), we could not follow the evolution of pore nor the process of the structural changes of the GUV. Here we used the term "local rupture" to express the rapid leakage of sucrose and determined the rate constant of local rupture, kL. On the basis of the comparison between kp and kL, we concluded that the leakage of calcein from single GUVs occurred as a result of a local rupture in the GUVs and that smaller pores inducing leakage of calcein were not formed before the local rupture. The results of the effect of the surface charge density of lipid membranes and that of salt concentration in buffer on kp clearly show that kp increases with an increase in the extent of electrostatic interactions due to

  20. Reserves in Context: Planning for Leakage from Protected Areas

    PubMed Central

    Renwick, Anna R.; Bode, Michael; Venter, Oscar

    2015-01-01

    When protected areas reduce threats within their boundaries, they often displace a portion of these threats into adjacent areas through a process known as ‘leakage’, undermining conservation objectives. Using theoretical models and a case study of terrestrial mammals in Indonesia, we develop the first theoretical explanation of how leakage impacts conservation actions, and highlight conservation strategies that mitigate these impacts. Although leakage is a socio-economic process, we demonstrate that its negative impacts are also affected by the distribution of species, with leakage having larger impacts in landscapes with homogeneous distribution of species richness. Moreover, leakage has a greater negative effect when conservation strategies are implemented opportunistically, even creating the potential for perversely negative consequences from protected area establishment. Leakage thereby increases the relative benefits of systematic conservation planning over opportunism, especially in areas with high leakage and heterogeneously distributed species. Although leakage has the potential to undermine conservation actions, conservation planning can minimize this risk. PMID:26053163