Science.gov

Sample records for air sampling network

  1. Use of Whatman-41 filters in air quality sampling networks (with applications to elemental analysis)

    NASA Technical Reports Server (NTRS)

    Neustadter, H. E.; Sidik, S. M.; King, R. B.; Fordyce, J. S.; Burr, J. C.

    1974-01-01

    The operation of a 16-site parallel high volume air sampling network with glass fiber filters on one unit and Whatman-41 filters on the other is reported. The network data and data from several other experiments indicate that (1) Sampler-to-sampler and filter-to-filter variabilities are small; (2) hygroscopic affinity of Whatman-41 filters need not introduce errors; and (3) suspended particulate samples from glass fiber filters averaged slightly, but not statistically significantly, higher than from Whatman-41-filters. The results obtained demonstrate the practicability of Whatman-41 filters for air quality monitoring and elemental analysis.

  2. Application of a dry-gas meter for measuring air sample volumes in an ambient air monitoring network

    SciTech Connect

    Fritz, Brad G.

    2009-05-24

    Ambient air monitoring for non-research applications (e.g. compliance) occurs at locations throughout the world. Often, the air sampling systems employed for these purposes employee simple yet robust equipment capable of handling the rigors of demanding sampling schedules. At the Hanford Site (near Richland, Washington) concentrations of radionuclides in ambient air are monitored continuously at 44 locations. In 2004, mechanical dry-gas meters were incorporated into the Hanford Site ambient air sample collection system to allow the direct measurement of sample volumes. These meters replaced a portable airflow measurement system that required two manual flow measurements and a sample duration measurement to determine sample volume. A six-month evaluation of the dry-gas meters compared sample volumes calculated using the original flow rate method to the direct sample volume measurement (new method). The results of the evaluation indicate that use of the dry-gas meters result in accurate sample volume measurements and provide greater confidence in the measured sample volumes. In several years of in-network use, the meters have proven to be reliable and have resulted in an improved sampling system.

  3. Sampling artifacts in active air sampling of semivolatile organic contaminants: Comparing theoretical and measured artifacts and evaluating implications for monitoring networks.

    PubMed

    Melymuk, Lisa; Bohlin-Nizzetto, Pernilla; Prokeš, Roman; Kukučka, Petr; Klánová, Jana

    2016-10-01

    The effects of sampling artifacts are often not fully considered in the design of air monitoring with active air samplers. Semivolatile organic contaminants (SVOCs) are particularly vulnerable to a range of sampling artifacts because of their wide range of gas-particle partitioning and degradation rates, and these can lead to erroneous measurements of air concentrations and a lack of comparability between sites with different environmental and sampling conditions. This study used specially adapted filter-sorbent sampling trains in three types of active air samplers to investigate breakthrough of SVOCs, and the possibility of other sampling artifacts. Breakthrough volumes were experimentally determined for a range of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) in sampling volumes from 300 to 10,000 m(3), and sampling durations of 1-7 days. In parallel, breakthrough was estimated based on theoretical sorbent-vapor pressure relationships. The comparison of measured and theoretical determinations of breakthrough demonstrated good agreement between experimental and estimated breakthrough volumes, and showed that theoretical breakthrough estimates should be used when developing air monitoring protocols. Significant breakthrough in active air samplers occurred for compounds with vapor pressure >0.5 Pa at volumes <700 m(3). Sample volumes between 700 and 10,000 m(3) may lead to breakthrough for compounds with vapor pressures between 0.005 and 0.5 Pa. Breakthrough is largely driven by sample volume and compound volatility (therefore indirectly by temperature) and is independent of sampler type. The presence of significant breakthrough at "typical" sampling conditions is relevant for air monitoring networks, and may lead to under-reporting of more volatile SVOCs.

  4. Air Traffic Network Project

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The high level requirement of the Air Traffic Network (ATN) project is to provide a mechanism for evaluating the impact of router scheduling modifications on a networks efficiency, without implementing the modifications in the live network.

  5. Single vessel air injection estimates of xylem resistance to cavitation are affected by vessel network characteristics and sample length.

    PubMed

    Venturas, Martin D; Rodriguez-Zaccaro, F Daniela; Percolla, Marta I; Crous, Casparus J; Jacobsen, Anna L; Pratt, R Brandon

    2016-10-01

    Xylem resistance to cavitation is an important trait that is related to the ecology and survival of plant species. Vessel network characteristics, such as vessel length and connectivity, could affect the spread of emboli from gas-filled vessels to functional ones, triggering their cavitation. We hypothesized that the cavitation resistance of xylem vessels is randomly distributed throughout the vessel network. We predicted that single vessel air injection (SVAI) vulnerability curves (VCs) would thus be affected by sample length. Longer stem samples were predicted to appear more resistant than shorter samples due to the sampled path including greater numbers of vessels. We evaluated the vessel network characteristics of grapevine (Vitis vinifera L.), English oak (Quercus robur L.) and black cottonwood (Populus trichocarpa Torr. & A. Gray), and constructed SVAI VCs for 5- and 20-cm-long segments. We also constructed VCs with a standard centrifuge method and used computer modelling to estimate the curve shift expected for pathways composed of different numbers of vessels. For all three species, the SVAI VCs for 5 cm segments rose exponentially and were more vulnerable than the 20 cm segments. The 5 cm curve shapes were exponential and were consistent with centrifuge VCs. Modelling data supported the observed SVAI VC shifts, which were related to path length and vessel network characteristics. These results suggest that exponential VCs represent the most realistic curve shape for individual vessel resistance distributions for these species. At the network level, the presence of some vessels with a higher resistance to cavitation may help avoid emboli spread during tissue dehydration.

  6. Sampling, storage, and analysis of C2-C7 non-methane hydrocarbons from the US National Oceanic and Atmospheric Administration Cooperative Air Sampling Network glass flasks.

    PubMed

    Pollmann, Jan; Helmig, Detlev; Hueber, Jacques; Plass-Dülmer, Christian; Tans, Pieter

    2008-04-25

    An analytical technique was developed to analyze light non-methane hydrocarbons (NMHC), including ethane, propane, iso-butane, n-butane, iso-pentane, n-pentane, n-hexane, isoprene, benzene and toluene from whole air samples collected in 2.5l-glass flasks used by the National Oceanic and Atmospheric Administration, Earth System Research Laboratory, Global Monitoring Division (NOAA ESRL GMD, Boulder, CO, USA) Cooperative Air Sampling Network. This method relies on utilizing the remaining air in these flasks (which is at below-ambient pressure at this stage) after the completion of all routine greenhouse gas measurements from these samples. NMHC in sample aliquots extracted from the flasks were preconcentrated with a custom-made, cryogen-free inlet system and analyzed by gas chromatography (GC) with flame ionization detection (FID). C2-C7 NMHC, depending on their ambient air mixing ratios, could be measured with accuracy and repeatability errors of generally < or =10-20%. Larger deviations were found for ethene and propene. Hexane was systematically overestimated due to a chromatographic co-elution problem. Saturated NMHC showed less than 5% changes in their mixing ratios in glass flask samples that were stored for up to 1 year. In the same experiment ethene and propene increased at approximately 30% yr(-1). A series of blank experiments showed negligible contamination from the sampling process and from storage (<10 pptv yr(-1)) of samples in these glass flasks. Results from flask NMHC analyses were compared to in-situ NMHC measurements at the Global Atmospheric Watch station in Hohenpeissenberg, Germany. This 9-months side-by-side comparison showed good agreement between both methods. More than 94% of all data comparisons for C2-C5 alkanes, isoprene, benzene and toluene fell within the combined accuracy and precision objectives of the World Meteorological Organization Global Atmosphere Watch (WMO-GAW) for NMHC measurements.

  7. Air Sampling Filter

    NASA Technical Reports Server (NTRS)

    1980-01-01

    General Metal Works' Accu-Vol is a high-volume air sampling system used by many government agencies to monitor air quality for pollution control purposes. Procedure prevents possible test-invalidating contamination from materials other than particulate pollutants, caused by manual handling or penetration of windblown matter during transit, a cassette was developed in which the filter is sealed within a metal frame and protected in transit by a snap-on aluminum cover, thus handled only under clean conditions in the laboratory.

  8. Towards a regional passive air sampling network and strategy for new POPs in the GRULAC region: Perspectives from the GAPS Network and first results for organophosphorus flame retardants.

    PubMed

    Rauert, Cassandra; Harner, Tom; Schuster, Jasmin K; Quinto, Karen; Fillmann, Gilberto; Castillo, Luisa Eugenia; Fentanes, Oscar; Ibarra, Martín Villa; Miglioranza, Karina S B; Rivadeneira, Isabel Moreno; Pozo, Karla; Puerta, Andrea Padilla; Zuluaga, Beatriz Helena Aristizábal

    2016-12-15

    A discussion is presented on the limitations for air monitoring studies around the Group of Latin American and Caribbean Countries (GRULAC), highlighting key issues requiring further attention, and reports on how a special initiative is addressing these limitations. Preliminary results are presented for the first reported data on organophosphorus flame retardant (OPFR) concentrations in outdoor air from the GRULAC region. At the majority of sites the concentrations and the profile of the OPFRs detected were similar with tris (chloroisopropyl) phosphate (TCPP) dominating (air levels. This preliminary study of only 7 sites highlights how extensive regional passive sampling networks (such as GAPS) can provide important new information to support risk assessment of these and similar chemicals. Finally, the various challenges with implementing a regional monitoring program are discussed, including harmonizing data from various monitoring programs for reporting to the GMP.

  9. Inertial impaction air sampling device

    SciTech Connect

    Dewhurst, K.H.

    1987-12-10

    An inertial impactor to be used in an air sampling device for collection of respirable size particles in ambient air which may include a graphite furnace as the impaction substrate in a small-size, portable, direct analysis structure that gives immediate results and is totally self-contained allowing for remote and/or personal sampling. The graphite furnace collects suspended particles transported through the housing by means of the air flow system, and these particles may be analyzed for elements, quantitatively and qualitatively, by atomic absorption spectrophotometry. 3 figs.

  10. Inertial impaction air sampling device

    SciTech Connect

    Dewhurst, K.H.

    1990-05-22

    An inertial impactor is designed which is to be used in an air sampling device for collection of respirable size particles in ambient air. The device may include a graphite furnace as the impaction substrate in a small-size, portable, direct analysis structure that gives immediate results and is totally self-contained allowing for remote and/or personal sampling. The graphite furnace collects suspended particles transported through the housing by means of the air flow system, and these particles may be analyzed for elements, quantitatively and qualitatively, by atomic absorption spectrophotometry. 3 figs.

  11. Inertial impaction air sampling device

    DOEpatents

    Dewhurst, Katharine H.

    1990-01-01

    An inertial impactor to be used in an air sampling device for collection of respirable size particles in ambient air which may include a graphite furnace as the impaction substrate in a small-size, portable, direct analysis structure that gives immediate results and is totally self-contained allowing for remote and/or personal sampling. The graphite furnace collects suspended particles transported through the housing by means of the air flow system, and these particles may be analyzed for elements, quantitatively and qualitatively, by atomic absorption spectrophotometry.

  12. Air sampling of smallpox virus

    PubMed Central

    Thomas, G.

    1974-01-01

    Airborne smallpox virus has been recovered in an isolation hospital using an adhesive surface sampling technique in the presence of very low aerosol concentrations. Previous work in this field is reviewed. Successful recovery of airborne virus depends on sampling large volumes of air with a suitable sampler and thorough investigation of the whole sample taken for the presence of viable virus. More information on the characteristics and behaviour of airborne smallpox virus is needed in particular with regard to the future design and siting of smallpox isolation units. PMID:4371586

  13. Sampling properties of directed networks

    NASA Astrophysics Data System (ADS)

    Son, S.-W.; Christensen, C.; Bizhani, G.; Foster, D. V.; Grassberger, P.; Paczuski, M.

    2012-10-01

    For many real-world networks only a small “sampled” version of the original network may be investigated; those results are then used to draw conclusions about the actual system. Variants of breadth-first search (BFS) sampling, which are based on epidemic processes, are widely used. Although it is well established that BFS sampling fails, in most cases, to capture the IN component(s) of directed networks, a description of the effects of BFS sampling on other topological properties is all but absent from the literature. To systematically study the effects of sampling biases on directed networks, we compare BFS sampling to random sampling on complete large-scale directed networks. We present new results and a thorough analysis of the topological properties of seven complete directed networks (prior to sampling), including three versions of Wikipedia, three different sources of sampled World Wide Web data, and an Internet-based social network. We detail the differences that sampling method and coverage can make to the structural properties of sampled versions of these seven networks. Most notably, we find that sampling method and coverage affect both the bow-tie structure and the number and structure of strongly connected components in sampled networks. In addition, at a low sampling coverage (i.e., less than 40%), the values of average degree, variance of out-degree, degree autocorrelation, and link reciprocity are overestimated by 30% or more in BFS-sampled networks and only attain values within 10% of the corresponding values in the complete networks when sampling coverage is in excess of 65%. These results may cause us to rethink what we know about the structure, function, and evolution of real-world directed networks.

  14. Air Sampling System Evaluation Template

    SciTech Connect

    Blunt, Brent

    2000-05-09

    The ASSET1.0 software provides a template with which a user can evaluate an Air Sampling System against the latest version of ANSI N13.1 "Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stacks and Ducts of Nuclear Facilities". The software uses the ANSI N13.1 PIC levels to establish basic design criteria for the existing or proposed sampling system. The software looks at such criteria as PIC level, type of radionuclide emissions, physical state of the radionuclide, nozzle entrance effects, particulate transmission effects, system and component accuracy and precision evaluations, and basic system operations to provide a detailed look at the subsystems of a monitoring and sampling system/program. A GAP evaluation can then be completed which leads to identification of design and operational flaws in the proposed systems. Corrective measures can then be limited to the GAPs.

  15. Air sampling in the workplace. Final report

    SciTech Connect

    Hickey, E.E.; Stoetzel, G.A.; Strom, D.J.; Cicotte, G.R.; Wiblin, C.M.; McGuire, S.A.

    1993-09-01

    This report provides technical information on air sampling that will be useful for facilities following the recommendations in the NRC`s Regulatory Guide 8.25, Revision 1, ``Air sampling in the Workplace.`` That guide addresses air sampling to meet the requirements in NRC`s regulations on radiation protection, 10 CFR Part 20. This report describes how to determine the need for air sampling based on the amount of material in process modified by the type of material, release potential, and confinement of the material. The purposes of air sampling and how the purposes affect the types of air sampling provided are discussed. The report discusses how to locate air samplers to accurately determine the concentrations of airborne radioactive materials that workers will be exposed to. The need for and the methods of performing airflow pattern studies to improve the accuracy of air sampling results are included. The report presents and gives examples of several techniques that can be used to evaluate whether the airborne concentrations of material are representative of the air inhaled by workers. Methods to adjust derived air concentrations for particle size are described. Methods to calibrate for volume of air sampled and estimate the uncertainty in the volume of air sampled are described. Statistical tests for determining minimum detectable concentrations are presented. How to perform an annual evaluation of the adequacy of the air sampling is also discussed.

  16. Assessment of SRS ambient air monitoring network

    SciTech Connect

    Abbott, K.; Jannik, T.

    2016-08-03

    Three methodologies have been used to assess the effectiveness of the existing ambient air monitoring system in place at the Savannah River Site in Aiken, SC. Effectiveness was measured using two metrics that have been utilized in previous quantification of air-monitoring network performance; frequency of detection (a measurement of how frequently a minimum number of samplers within the network detect an event), and network intensity (a measurement of how consistent each sampler within the network is at detecting events). In addition to determining the effectiveness of the current system, the objective of performing this assessment was to determine what, if any, changes could make the system more effective. Methodologies included 1) the Waite method of determining sampler distribution, 2) the CAP88- PC annual dose model, and 3) a puff/plume transport model used to predict air concentrations at sampler locations. Data collected from air samplers at SRS in 2015 compared with predicted data resulting from the methodologies determined that the frequency of detection for the current system is 79.2% with sampler efficiencies ranging from 5% to 45%, and a mean network intensity of 21.5%. One of the air monitoring stations had an efficiency of less than 10%, and detected releases during just one sampling period of the entire year, adding little to the overall network intensity. By moving or removing this sampler, the mean network intensity increased to about 23%. Further work in increasing the network intensity and simulating accident scenarios to further test the ambient air system at SRS is planned

  17. Community Air Sensor Network (CAIRSENSE) project ...

    EPA Pesticide Factsheets

    Advances in air pollution sensor technology have enabled the development of small and low cost systems to measure outdoor air pollution. The deployment of a large number of sensors across a small geographic area would have potential benefits to supplement traditional monitoring networks with additional geographic and temporal measurement resolution, if the data quality were sufficient. To understand the capability of emerging air sensor technology, the Community Air Sensor Network (CAIRSENSE) project deployed low cost, continuous and commercially-available air pollution sensors at a regulatory air monitoring site and as a local sensor network over a surrounding ~2 km area in Southeastern U.S. Co-location of sensors measuring oxides of nitrogen, ozone, carbon monoxide, sulfur dioxide, and particles revealed highly variable performance, both in terms of comparison to a reference monitor as well as whether multiple identical sensors reproduced the same signal. Multiple ozone, nitrogen dioxide, and carbon monoxide sensors revealed low to very high correlation with a reference monitor, with Pearson sample correlation coefficient (r) ranging from 0.39 to 0.97, -0.25 to 0.76, -0.40 to 0.82, respectively. The only sulfur dioxide sensor tested revealed no correlation (r 0.5), step-wise multiple linear regression was performed to determine if ambient temperature, relative humidity (RH), or age of the sensor in sampling days could be used in a correction algorihm to im

  18. Partitioning of ocean and land uptake of CO2 as inferred by delta C-13 measurements from the NOAA Climate Monitoring and Diagnostics Laboratory Global Air Sampling Network

    SciTech Connect

    Ciais, P.; Tans, P.P.; White, J.W.C.; Trolier, M.; Francey, R.J.; Berry, J.A.; Randall, D.R.; Sellers, P.J.; Collatz, J.G.; Schimel, D.S. ||||||

    1995-03-01

    Using delta C-13 measurements in atmospheric CO2 from a cooperative global air sampling network, we determined the partitioning of the net uptake of CO2 between ocean and land as a function of latitude and time. The majority of delta C-13 measurements were made at the Institute of Arctic and Alpine Research (INSTAAR) of the University of Colorado. We perform an inverse deconvolution of both CO2 and delta C-13 observations, using a two-dimensional model of atmospheric transport. Also, the discrimination against C-13 by plant photosynthesis, as a function of latitude and time, is calculated from global runs of the simple biosphere (SiB) model. Uncertainty due to the longitudinal structure of the data, which is not represented by the model, is studied through a bootstrap analysis by adding and omitting measurement sites. The resulting error estimates for our inferred sources and sinks are of the order of 1 GTC (1 GTC = 10(exp 15) gC). Such error bars do not reflect potential systematic errors arising from our estimates of the isotopic disequilibria between the atmosphere and the oceans and biosphere, which are estimated in a separate sensitivity analysis. With respect to global totals for 1992 we found that 3.2 GTC of carbon dissolved into the ocean and that 1.5 GTC were sequestered by land ecosystems. Northern hemisphere ocean gyres north of 15 deg N absorbed 2.7 GTC. The equatorial oceans between 10 deg S and 10 deg N were a net source to the atmosphere of 0.9 GTC.

  19. A New Technique for Sampling Firn Air

    NASA Astrophysics Data System (ADS)

    Perron, F. E.; Dibb, J. E.; Albert, M. R.

    2004-12-01

    The discovery and subsequent interest in photochemical interactions between the polar snowpack and the atmosphere has spawned interest in reliable methods of measuring chemical concentrations in interstitial air. Consistent sampling of the interstitial air in the snowpack had been problematic due to great chemical differences possible from sampling different layers in the snow and the difficulties in acquiring a sample that could serve multiple investigators at the same time. This paper describes a new air sampling device that was developed to solve many of the sampling problems. This new system allows multiple simultaneous chemical analysis of air contained in the pore spaces of the arctic snowpack at unlimited increments from depths of 0 to 150 cm. The three major components are a 4 ft diameter highly UV transmittent acrylic "hood" with a 10 cm rim, a 10 cm diameter casing barrel, and an air probe head. These components operate along with a variety of sub-components that supplement the sampling process. The technique provides for a common sample collection, use for a variety of gases to be sampled, it eliminates short circuit air sampling, provides undisturbed snow for in-situ sampling at multiple sample depths in the same location. The design is discussed and possible extension as a platform for other sensors is described.

  20. Partitioning of ocean and land uptake of CO2 as inferred by delta C-13 measurements from the NOAA Climate Monitoring and Diagnostics Laboratory Global Air Sampling Network

    NASA Technical Reports Server (NTRS)

    Ciais, Philippe; Tans, Pieter P.; White, James W. C.; Trolier, Michael; Francey, Roger J.; Berry, Joe A.; Randall, David R.; Sellers, Piers J.; Collatz, James G.; Schimel, David S.

    1995-01-01

    Using delta C-13 measurements in atmospheric CO2 from a cooperative global air sampling network, we determined the partitioning of the net uptake of CO2 between ocean and land as a function of latitude and time. The majority of delta C-13 measurements were made at the Institute of Arctic and Alpine Research (INSTAAR) of the University of Colorado. We perform an inverse deconvolution of both CO2 and delta C-13 observations, using a two-dimensional model of atmospheric transport. Also, the discrimination against C-13 by plant photosynthesis, as a function of latitude and time, is calculated from global runs of the simple biosphere (SiB) model. Uncertainty due to the longitudinal structure of the data, which is not represented by the model, is studied through a bootstrap analysis by adding and omitting measurement sites. The resulting error estimates for our inferred sources and sinks are of the order of 1 GTC (1 GTC = 10(exp 15) gC). Such error bars do not reflect potential systematic errors arising from our estimates of the isotopic disequilibria between the atmosphere and the oceans and biosphere, which are estimated in a separate sensitivity analysis. With respect to global totals for 1992 we found that 3.2 GTC of carbon dissolved into the ocean and that 1.5 GTC were sequestered by land ecosystems. Northern hemisphere ocean gyres north of 15 deg N absorbed 2.7 GTC. The equatorial oceans between 10 deg S and 10 deg N were a net source to the atmosphere of 0.9 GTC. We obtained a sink of 1.6 GTC in southern ocean gyres south of 20 deg S, although the deconvolution is poorly constrained by sparse data coverage at high southern latitudes. The seasonal uptake of CO2 in the northern gyres appears to be correlated with a bloom of phytoplankton in surface waters. On land, northern temperate and boreal ecosystems between 35 deg N and 65 deg N were found to be a major sink of CO2 in 1992, as large as 3.5 GTC. Northern tropical ecosystems (equator-30 deg N) appear to be a net

  1. Air sampling with solid phase microextraction

    NASA Astrophysics Data System (ADS)

    Martos, Perry Anthony

    There is an increasing need for simple yet accurate air sampling methods. The acceptance of new air sampling methods requires compatibility with conventional chromatographic equipment, and the new methods have to be environmentally friendly, simple to use, yet with equal, or better, detection limits, accuracy and precision than standard methods. Solid phase microextraction (SPME) satisfies the conditions for new air sampling methods. Analyte detection limits, accuracy and precision of analysis with SPME are typically better than with any conventional air sampling methods. Yet, air sampling with SPME requires no pumps, solvents, is re-usable, extremely simple to use, is completely compatible with current chromatographic equipment, and requires a small capital investment. The first SPME fiber coating used in this study was poly(dimethylsiloxane) (PDMS), a hydrophobic liquid film, to sample a large range of airborne hydrocarbons such as benzene and octane. Quantification without an external calibration procedure is possible with this coating. Well understood are the physical and chemical properties of this coating, which are quite similar to those of the siloxane stationary phase used in capillary columns. The log of analyte distribution coefficients for PDMS are linearly related to chromatographic retention indices and to the inverse of temperature. Therefore, the actual chromatogram from the analysis of the PDMS air sampler will yield the calibration parameters which are used to quantify unknown airborne analyte concentrations (ppb v to ppm v range). The second fiber coating used in this study was PDMS/divinyl benzene (PDMS/DVB) onto which o-(2,3,4,5,6- pentafluorobenzyl) hydroxylamine (PFBHA) was adsorbed for the on-fiber derivatization of gaseous formaldehyde (ppb v range), with and without external calibration. The oxime formed from the reaction can be detected with conventional gas chromatographic detectors. Typical grab sampling times were as small as 5 seconds

  2. East Mountain Area 1995 air sampling results

    SciTech Connect

    Deola, R.A.

    1996-09-01

    Ambient air samples were taken at two locations in the East Mountain Area in conjunction with thermal testing at the Lurance Canyon Burn Site (LCBS). The samples were taken to provide measurements of particulate matter with a diameter less than or equal to 10 micrometers (PM{sub 10}) and volatile organic compounds (VOCs). This report summarizes the results of the sampling performed in 1995. The results from small-scale testing performed to determine the potentially produced air pollutants in the thermal tests are included in this report. Analytical results indicate few samples produced measurable concentrations of pollutants believed to be produced by thermal testing. Recommendations for future air sampling in the East Mountain Area are also noted.

  3. Social network sampling using spanning trees

    NASA Astrophysics Data System (ADS)

    Jalali, Zeinab S.; Rezvanian, Alireza; Meybodi, Mohammad Reza

    2016-12-01

    Due to the large scales and limitations in accessing most online social networks, it is hard or infeasible to directly access them in a reasonable amount of time for studying and analysis. Hence, network sampling has emerged as a suitable technique to study and analyze real networks. The main goal of sampling online social networks is constructing a small scale sampled network which preserves the most important properties of the original network. In this paper, we propose two sampling algorithms for sampling online social networks using spanning trees. The first proposed sampling algorithm finds several spanning trees from randomly chosen starting nodes; then the edges in these spanning trees are ranked according to the number of times that each edge has appeared in the set of found spanning trees in the given network. The sampled network is then constructed as a sub-graph of the original network which contains a fraction of nodes that are incident on highly ranked edges. In order to avoid traversing the entire network, the second sampling algorithm is proposed using partial spanning trees. The second sampling algorithm is similar to the first algorithm except that it uses partial spanning trees. Several experiments are conducted to examine the performance of the proposed sampling algorithms on well-known real networks. The obtained results in comparison with other popular sampling methods demonstrate the efficiency of the proposed sampling algorithms in terms of Kolmogorov-Smirnov distance (KSD), skew divergence distance (SDD) and normalized distance (ND).

  4. Innovations in air sampling to detect plant pathogens.

    PubMed

    West, Js; Kimber, Rbe

    2015-01-01

    Many innovations in the development and use of air sampling devices have occurred in plant pathology since the first description of the Hirst spore trap. These include improvements in capture efficiency at relatively high air-volume collection rates, methods to enhance the ease of sample processing with downstream diagnostic methods and even full automation of sampling, diagnosis and wireless reporting of results. Other innovations have been to mount air samplers on mobile platforms such as UAVs and ground vehicles to allow sampling at different altitudes and locations in a short space of time to identify potential sources and population structure. Geographical Information Systems and the application to a network of samplers can allow a greater prediction of airborne inoculum and dispersal dynamics. This field of technology is now developing quickly as novel diagnostic methods allow increasingly rapid and accurate quantifications of airborne species and genetic traits. Sampling and interpretation of results, particularly action-thresholds, is improved by understanding components of air dispersal and dilution processes and can add greater precision in the application of crop protection products as part of integrated pest and disease management decisions. The applications of air samplers are likely to increase, with much greater adoption by growers or industry support workers to aid in crop protection decisions. The same devices are likely to improve information available for detection of allergens causing hay fever and asthma or provide valuable metadata for regional plant disease dynamics.

  5. Innovations in air sampling to detect plant pathogens

    PubMed Central

    West, JS; Kimber, RBE

    2015-01-01

    Many innovations in the development and use of air sampling devices have occurred in plant pathology since the first description of the Hirst spore trap. These include improvements in capture efficiency at relatively high air-volume collection rates, methods to enhance the ease of sample processing with downstream diagnostic methods and even full automation of sampling, diagnosis and wireless reporting of results. Other innovations have been to mount air samplers on mobile platforms such as UAVs and ground vehicles to allow sampling at different altitudes and locations in a short space of time to identify potential sources and population structure. Geographical Information Systems and the application to a network of samplers can allow a greater prediction of airborne inoculum and dispersal dynamics. This field of technology is now developing quickly as novel diagnostic methods allow increasingly rapid and accurate quantifications of airborne species and genetic traits. Sampling and interpretation of results, particularly action-thresholds, is improved by understanding components of air dispersal and dilution processes and can add greater precision in the application of crop protection products as part of integrated pest and disease management decisions. The applications of air samplers are likely to increase, with much greater adoption by growers or industry support workers to aid in crop protection decisions. The same devices are likely to improve information available for detection of allergens causing hay fever and asthma or provide valuable metadata for regional plant disease dynamics. PMID:25745191

  6. Air Sampling Instruments for Evaluation of Atmospheric Contaminants. Fourth Edition.

    ERIC Educational Resources Information Center

    American Conference of Governmental Industrial Hygienists, Cincinnati, OH.

    This text, a revision and extension of the first three editions, consists of papers discussing the basic considerations in sampling air for specific purposes, sampler calibration, systems components, sample collectors, and descriptions of air-sampling instruments. (BT)

  7. More about sampling and estimation of mercaptans in air samples.

    PubMed

    Moliner-Martínez, Y; Herráez-Hernández, R; Molins-Legua, C; Verdú-Andrés, J; Avella-Oliver, M; Campíns-Falcó, P

    2013-03-15

    Several strategies have been developed for sampling and determination of volatile thiols. The selectivity and sensitivity of the proposed methodologies are achieved by using a specific derivatizing reagent. The different procedures assayed are based on air sampling followed by derivatization of the analytes with OPA and isoleucine in alkaline solution. The derivatization products are separated and determined by liquid chromatography and fluorescence detection. To start, the derivatization conditions and stability of the derivates have been studied in order to establish the storage conditions. In general, the strategies studied consisted on trapping and detivatization the thiol compound on different support; a solution (Impinger) or sorbent (C₁₈ cartridges or glass fiber filter). The analytical properties of the different strategies have been obtained and compared. Procedures are recommended upon specific situations.

  8. Balloon Operation for Stratospheric Air Sampling at Antarctica

    NASA Astrophysics Data System (ADS)

    Honda, H.; Yajima, N.; Yamagami, T.; Aoki, S.; Hashida, G.; Machida, T.; Morimoto, S.

    On January 3rd, 1998, a cryogenic air sampling experiment was carried out at Syowa Station (69S, 40E), which is the first successful trial in the world for collection of large amount of stratospheric air over the Antarctic. The samples are analyzed for CO2, CH4, CFCs, and C and O isotope ratios in CO2 in the laboratories. As the meteorological conditions for launching and payload recovery are both critical, feasibility on wind conditions over Syowa Station was studied in detail. The balloon launching operations had to be performed without a specialist. Facilities for balloon launching, tracking, and other support systems were newly designed for ready-to- and easy-to-use. Realtime remote support from Japan for the balloon launching and flight control operations was applied using a computer network linked by INMARSAT

  9. Neural Network Classification of Environmental Samples

    DTIC Science & Technology

    1996-12-01

    Biological and Artificial Neural Networks. Air Force Institute of Technology, 1990. 24. Rosenblatt. Principles of Neurodynamics . New York, NY: Spartan...Parallel Distributed Processing: Explorations in the Microstructure of Cognition . MIT Press, 1986. 29. Smagt, Patrick P. Van Der. "Minimisation Methods

  10. 40 CFR 61.34 - Air sampling.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Beryllium § 61.34 Air... detect maximum concentrations of beryllium in the ambient air. (b) All monitoring sites shall be...

  11. 40 CFR 61.34 - Air sampling.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Beryllium § 61.34 Air... detect maximum concentrations of beryllium in the ambient air. (b) All monitoring sites shall be...

  12. 40 CFR 61.34 - Air sampling.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Beryllium § 61.34 Air... detect maximum concentrations of beryllium in the ambient air. (b) All monitoring sites shall be...

  13. 40 CFR 61.34 - Air sampling.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Beryllium § 61.34 Air... detect maximum concentrations of beryllium in the ambient air. (b) All monitoring sites shall be...

  14. 40 CFR 61.34 - Air sampling.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Beryllium § 61.34 Air... detect maximum concentrations of beryllium in the ambient air. (b) All monitoring sites shall be...

  15. Sampling Motif-Constrained Ensembles of Networks

    NASA Astrophysics Data System (ADS)

    Fischer, Rico; Leitão, Jorge C.; Peixoto, Tiago P.; Altmann, Eduardo G.

    2015-10-01

    The statistical significance of network properties is conditioned on null models which satisfy specified properties but that are otherwise random. Exponential random graph models are a principled theoretical framework to generate such constrained ensembles, but which often fail in practice, either due to model inconsistency or due to the impossibility to sample networks from them. These problems affect the important case of networks with prescribed clustering coefficient or number of small connected subgraphs (motifs). In this Letter we use the Wang-Landau method to obtain a multicanonical sampling that overcomes both these problems. We sample, in polynomial time, networks with arbitrary degree sequences from ensembles with imposed motifs counts. Applying this method to social networks, we investigate the relation between transitivity and homophily, and we quantify the correlation between different types of motifs, finding that single motifs can explain up to 60% of the variation of motif profiles.

  16. Minanre Gas Concentrators For Air Sampling

    SciTech Connect

    Dr. Seung Ho Hong

    2001-03-01

    The goal of this project was to demonstrate the feasibility of a compact, lightweight, gas-sampling device with rapid-cycle-time characteristics. The highlights of our Phase I work include: (1) Demonstration of a compact gas sampler with integrated heater. This device has an order of magnitude greater adsorption capacity and much faster heating/cooling times than commercial sorbent tubes. (2) Completion of computational fluid dynamics modeling of the gas sampler to determine airflow characteristics for various design options. These modeling efforts guided the development and testing of the Mesochannel Gas Sampler prototype. (3) Testing of the Mesochannel Gas Sampler in parallel with tests of two packed-bed samplers. These tests showed the Mesochannel Gas Sampler represents a substantial improvement compared with the packed-bed approach. Our mesochannel heat-exchanger/adsorber architecture allows very efficient use of adsorbent mass, high adsorbent loadings, and very low pressure drop, which makes possible very high air-sampling rates using a simple, low-power fan. This device is well-suited for collecting samples of trace-level contaminants. The integrated heater, which forms the adsorbent-coated mesochannel walls, allows direct heating of the adsorbent and results in very rapid desorption of the adsorbed species. We believe the Mesochannel Gas Sampler represents a promising technology for the improvement of trace-contaminant detection limits. In our Phase II proposal, we outline several improvements to the gas sampler that will further improve its performance.

  17. Network Sampling with Memory: A proposal for more efficient sampling from social networks

    PubMed Central

    Mouw, Ted; Verdery, Ashton M.

    2013-01-01

    Techniques for sampling from networks have grown into an important area of research across several fields. For sociologists, the possibility of sampling from a network is appealing for two reasons: (1) A network sample can yield substantively interesting data about network structures and social interactions, and (2) it is useful in situations where study populations are difficult or impossible to survey with traditional sampling approaches because of the lack of a sampling frame. Despite its appeal, methodological concerns about the precision and accuracy of network-based sampling methods remain. In particular, recent research has shown that sampling from a network using a random walk based approach such as Respondent Driven Sampling (RDS) can result in high design effects (DE)—the ratio of the sampling variance to the sampling variance of simple random sampling (SRS). A high design effect means that more cases must be collected to achieve the same level of precision as SRS. In this paper we propose an alternative strategy, Network Sampling with Memory (NSM), which collects network data from respondents in order to reduce design effects and, correspondingly, the number of interviews needed to achieve a given level of statistical power. NSM combines a “List” mode, where all individuals on the revealed network list are sampled with the same cumulative probability, with a “Search” mode, which gives priority to bridge nodes connecting the current sample to unexplored parts of the network. We test the relative efficiency of NSM compared to RDS and SRS on 162 school and university networks from Add Health and Facebook that range in size from 110 to 16,278 nodes. The results show that the average design effect for NSM on these 162 networks is 1.16, which is very close to the efficiency of a simple random sample (DE=1), and 98.5% lower than the average DE we observed for RDS. PMID:24159246

  18. Sampling of Complex Networks: A Datamining Approach

    NASA Astrophysics Data System (ADS)

    Loecher, Markus; Dohrmann, Jakob; Bauer, Gernot

    2007-03-01

    Efficient and accurate sampling of big complex networks is still an unsolved problem. As the degree distribution is one of the most commonly used attributes to characterize a network, there have been many attempts in recent papers to derive the original degree distribution from the data obtained during a traceroute- like sampling process. This talk describes a strategy for predicting the original degree of a node using the data obtained from a network by traceroute-like sampling making use of datamining techniques. Only local quantities (the sampled degree k, the redundancy of node detection r, the time of the first discovery of a node t and the distance to the sampling source d) are used as input for the datamining models. Global properties like the betweenness centrality are ignored. These local quantities are examined theoretically and in simulations to increase their value for the predictions. The accuracy of the models is discussed as a function of the number of sources used in the sampling process and the underlying topology of the network. The purpose of this work is to introduce the techniques of the relatively young field of datamining to the discussion on network sampling.

  19. U.S. emissions of HFC-134a derived for 2008-2012 from an extensive flask-air sampling network

    NASA Astrophysics Data System (ADS)

    Hu, Lei; Montzka, Stephen A.; Miller, John B.; Andrews, Aryln E.; Lehman, Scott J.; Miller, Benjamin R.; Thoning, Kirk; Sweeney, Colm; Chen, Huilin; Godwin, David S.; Masarie, Kenneth; Bruhwiler, Lori; Fischer, Marc L.; Biraud, Sebastien C.; Torn, Margaret S.; Mountain, Marikate; Nehrkorn, Thomas; Eluszkiewicz, Janusz; Miller, Scot; Draxler, Roland R.; Stein, Ariel F.; Hall, Bradley D.; Elkins, James W.; Tans, Pieter P.

    2015-01-01

    national and regional emissions of HFC-134a are derived for 2008-2012 based on atmospheric observations from ground and aircraft sites across the U.S. and a newly developed regional inverse model. Synthetic data experiments were first conducted to optimize the model assimilation design and to assess model-data mismatch errors and prior flux error covariances computed using a maximum likelihood estimation technique. The synthetic data experiments also tested the sensitivity of derived national and regional emissions to a range of assumed prior emissions, with the goal of designing a system that was minimally reliant on the prior. We then explored the influence of additional sources of error in inversions with actual observations, such as those associated with background mole fractions and transport uncertainties. Estimated emissions of HFC-134a range from 52 to 61 Gg yr-1 for the contiguous U.S. during 2008-2012 for inversions using air transport from Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model driven by the 12 km resolution meteorogical data from North American Mesoscale Forecast System (NAM12) and all tested combinations of prior emissions and background mole fractions. Estimated emissions for 2008-2010 were 20% lower when specifying alternative transport from Stochastic Time-Inverted Lagrangian Transport (STILT) model driven by the Weather Research and Forecasting (WRF) meteorology. Our estimates (for HYSPLIT-NAM12) are consistent with annual emissions reported by U.S. Environmental Protection Agency for the full study interval. The results suggest a 10-20% drop in U.S. national HFC-134a emission in 2009 coincident with a reduction in transportation-related fossil fuel CO2 emissions, perhaps related to the economic recession. All inversions show seasonal variation in national HFC-134a emissions in all years, with summer emissions greater than winter emissions by 20-50%.

  20. Systematic Evaluation of Aggressive Air Sampling for Bacillus ...

    EPA Pesticide Factsheets

    Report The primary objectives of this project were to evaluate the Aggressive Air Sampling (AAS) method compared to currently used surface sampling methods and to determine if AAS is a viable option for sampling Bacillus anthracis spores.

  1. Maximizing algebraic connectivity in air transportation networks

    NASA Astrophysics Data System (ADS)

    Wei, Peng

    In air transportation networks the robustness of a network regarding node and link failures is a key factor for its design. An experiment based on the real air transportation network is performed to show that the algebraic connectivity is a good measure for network robustness. Three optimization problems of algebraic connectivity maximization are then formulated in order to find the most robust network design under different constraints. The algebraic connectivity maximization problem with flight routes addition or deletion is first formulated. Three methods to optimize and analyze the network algebraic connectivity are proposed. The Modified Greedy Perturbation Algorithm (MGP) provides a sub-optimal solution in a fast iterative manner. The Weighted Tabu Search (WTS) is designed to offer a near optimal solution with longer running time. The relaxed semi-definite programming (SDP) is used to set a performance upper bound and three rounding techniques are discussed to find the feasible solution. The simulation results present the trade-off among the three methods. The case study on two air transportation networks of Virgin America and Southwest Airlines show that the developed methods can be applied in real world large scale networks. The algebraic connectivity maximization problem is extended by adding the leg number constraint, which considers the traveler's tolerance for the total connecting stops. The Binary Semi-Definite Programming (BSDP) with cutting plane method provides the optimal solution. The tabu search and 2-opt search heuristics can find the optimal solution in small scale networks and the near optimal solution in large scale networks. The third algebraic connectivity maximization problem with operating cost constraint is formulated. When the total operating cost budget is given, the number of the edges to be added is not fixed. Each edge weight needs to be calculated instead of being pre-determined. It is illustrated that the edge addition and the

  2. Characterizing air quality data from complex network perspective.

    PubMed

    Fan, Xinghua; Wang, Li; Xu, Huihui; Li, Shasha; Tian, Lixin

    2016-02-01

    Air quality depends mainly on changes in emission of pollutants and their precursors. Understanding its characteristics is the key to predicting and controlling air quality. In this study, complex networks were built to analyze topological characteristics of air quality data by correlation coefficient method. Firstly, PM2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) indexes of eight monitoring sites in Beijing were selected as samples from January 2013 to December 2014. Secondly, the C-C method was applied to determine the structure of phase space. Points in the reconstructed phase space were considered to be nodes of the network mapped. Then, edges were determined by nodes having the correlation greater than a critical threshold. Three properties of the constructed networks, degree distribution, clustering coefficient, and modularity, were used to determine the optimal value of the critical threshold. Finally, by analyzing and comparing topological properties, we pointed out that similarities and difference in the constructed complex networks revealed influence factors and their different roles on real air quality system.

  3. The TOMPs ambient air monitoring network - Continuous data on UK air quality for over 20 years.

    PubMed

    Graf, Carola; Katsoyiannis, Athanasios; Jones, Kevin C; Sweetman, Andrew J

    2016-10-01

    Long-term air monitoring datasets are needed for persistent organic pollutants (POPs) to assess the effectiveness of source abatement measures and the factors controlling ambient levels. The Toxic Organic Micro Pollutants (TOMPs) Network, which has operated since 1991, collects ambient air samples at six sites across England and Scotland, using high-volume active air samplers. The network provides long-term ambient air trend data for a range of POPs at both urban and rural locations. Data from the network provides the UK Government, regulators and researchers with valuable information on emission/source controls and on the effectiveness of international chemicals regulation such as the Stockholm Convention and UN/ECE Protocol on POPs. The target chemicals of TOMPs have been polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and, since 2010, polybrominated diphenyl ethers (PBDEs). The continuous monitoring of these compounds demonstrates the constant decline in UK air concentrations over the last two decades, with average clearance rates for PCDD/Fs in urban locations of 5.1 years and for PCBs across all sites 6.6 years. No significant declines in rural locations for PCDD/Fs have been observed. There is a strong observable link between the declining ambient air concentrations and the emission reductions estimated in the annually produced National Atmospheric Emission Inventory (NAEI) dataset. These findings clearly demonstrate the unique strengths of long-term consistent datasets for the evaluation of the success of chemical regulation and control.

  4. Congestion transition in air traffic networks.

    PubMed

    Monechi, Bernardo; Servedio, Vito D P; Loreto, Vittorio

    2015-01-01

    Air Transportation represents a very interesting example of a complex techno-social system whose importance has considerably grown in time and whose management requires a careful understanding of the subtle interplay between technological infrastructure and human behavior. Despite the competition with other transportation systems, a growth of air traffic is still foreseen in Europe for the next years. The increase of traffic load could bring the current Air Traffic Network above its capacity limits so that safety standards and performances might not be guaranteed anymore. Lacking the possibility of a direct investigation of this scenario, we resort to computer simulations in order to quantify the disruptive potential of an increase in traffic load. To this end we model the Air Transportation system as a complex dynamical network of flights controlled by humans who have to solve potentially dangerous conflicts by redirecting aircraft trajectories. The model is driven and validated through historical data of flight schedules in a European national airspace. While correctly reproducing actual statistics of the Air Transportation system, e.g., the distribution of delays, the model allows for theoretical predictions. Upon an increase of the traffic load injected in the system, the model predicts a transition from a phase in which all conflicts can be successfully resolved, to a phase in which many conflicts cannot be resolved anymore. We highlight how the current flight density of the Air Transportation system is well below the transition, provided that controllers make use of a special re-routing procedure. While the congestion transition displays a universal scaling behavior, its threshold depends on the conflict solving strategy adopted. Finally, the generality of the modeling scheme introduced makes it a flexible general tool to simulate and control Air Transportation systems in realistic and synthetic scenarios.

  5. Congestion Transition in Air Traffic Networks

    PubMed Central

    Monechi, Bernardo; Servedio, Vito D. P.; Loreto, Vittorio

    2015-01-01

    Air Transportation represents a very interesting example of a complex techno-social system whose importance has considerably grown in time and whose management requires a careful understanding of the subtle interplay between technological infrastructure and human behavior. Despite the competition with other transportation systems, a growth of air traffic is still foreseen in Europe for the next years. The increase of traffic load could bring the current Air Traffic Network above its capacity limits so that safety standards and performances might not be guaranteed anymore. Lacking the possibility of a direct investigation of this scenario, we resort to computer simulations in order to quantify the disruptive potential of an increase in traffic load. To this end we model the Air Transportation system as a complex dynamical network of flights controlled by humans who have to solve potentially dangerous conflicts by redirecting aircraft trajectories. The model is driven and validated through historical data of flight schedules in a European national airspace. While correctly reproducing actual statistics of the Air Transportation system, e.g., the distribution of delays, the model allows for theoretical predictions. Upon an increase of the traffic load injected in the system, the model predicts a transition from a phase in which all conflicts can be successfully resolved, to a phase in which many conflicts cannot be resolved anymore. We highlight how the current flight density of the Air Transportation system is well below the transition, provided that controllers make use of a special re-routing procedure. While the congestion transition displays a universal scaling behavior, its threshold depends on the conflict solving strategy adopted. Finally, the generality of the modeling scheme introduced makes it a flexible general tool to simulate and control Air Transportation systems in realistic and synthetic scenarios. PMID:25993476

  6. EVALUATION OF THE FILTER PACK FOR LONG-DURATION SAMPLING OF AMBIENT AIR

    EPA Science Inventory

    A 14-week filter pack (FP) sampler evaluation field study was conducted at a site near Bondville, IL to investigate the impact of weekly sampling duration. Simultaneous samples were collected using collocated filter packs (FP) from two independent air quality monitoring networks...

  7. Sampling Interplanetary Dust Particles from Antarctic Air

    NASA Astrophysics Data System (ADS)

    Taylor, S.; Lever, J. H.; Alexander, C. M. O'D.; Brownlee, D. E.; Messenger, S.; Littler, L. R.; Stroud, R. M.; Wozniakiewicz, P.; Clement, S.

    2016-08-01

    We are undertaking a NASA and NSF supported project to filter large volumes of clean Antarctic air to collect a broad range of cosmic dust, including CP-IDPs, rare ultra-carbonaceous particles and particles derived from specific meteor streams.

  8. Evaluation of Urban Air Quality By Passive Sampling Technique

    NASA Astrophysics Data System (ADS)

    Nunes, T. V.; Miranda, A. I.; Duarte, S.; Lima, M. J.

    Aveiro is a flat small city in the centre of Portugal, close to the Atlantic coast. In the last two decades an intensive development of demographic, traffic and industry growth in the region was observed which was reflected on the air quality degrada- tion. In order to evaluate the urban air quality in Aveiro, a field-monitoring network by passive sampling with high space resolution was implemented. Twenty-four field places were distributed in a area of 3x3 Km2 and ozone and NO2 concentrations were measured. The site distribution density was higher in the centre, 250x250 m2 than in periphery where a 500x500 m2 grid was used. The selection of field places took into consideration the choice criteria recommendation by United Kingdom environmental authorities, and three tubes and a blank tube for each pollutant were used at each site. The sampling system was mounted at 3m from the ground usually profiting the street lampposts. Concerning NO2 acrylic tubes were used with 85 mm of length and an in- ternal diameter of 12mm, where in one of the extremities three steel grids impregnated with a solution of TEA were placed and fixed with a polyethylene end cup (Heal et al., 1999); PFA Teflon tube with 53 mm of length and 9 mm of internal diameter and three impregnated glass filters impregnated with DPE solution fixed by a teflon end cup was used for ozone sampling (Monn and Hargartner, 1990). The passive sampling method for ozone and nitrogen dioxide was compared with continuous measurements, but the amount of measurements wasnSt enough for an accurate calibration and validation of the method. Although this constraint the field observations (June to August 2001) for these two pollutants assign interesting information about the air quality in the urban area. A krigger method of interpolation (Surfer- Golden Software-2000) was applied to field data to obtain isolines distribution of NO2 and ozone concentration for the studied area. Even the used passive sampling method has many

  9. Venturi Air-Jet Vacuum Ejector For Sampling Air

    NASA Technical Reports Server (NTRS)

    Hill, Gerald F.; Sachse, Glen W.; Burney, L. Garland; Wade, Larry O.

    1990-01-01

    Venturi air-jet vacuum ejector pump light in weight, requires no electrical power, does not contribute heat to aircraft, and provides high pumping speeds at moderate suctions. High-pressure motive gas required for this type of pump bled from compressor of aircraft engine with negligible effect on performance of engine. Used as source of vacuum for differential-absorption CO-measurement (DACOM), modified to achieve in situ measurements of CO at frequency response of 10 Hz. Provides improvement in spatial resolution and potentially leads to capability to measure turbulent flux of CO by use of eddy-correlation technique.

  10. Workplace air monitoring and sampling practices at DOE facilities

    SciTech Connect

    Swinth, K.L.; Kenoyer, J.L.; Selby, J.M.; Vallario, E.J.; Burphy, B.L.

    1986-03-01

    Current air monitoring and sampling practices at DOE facilities were surveyed as a part of an air monitoring upgrade task. A comprehensive questionnaire was developed and distributed to DOE contractors through the DOE field offices. Twenty-six facilities returned a completed questionnaire. Questionnaire replies indicate diversity in air sampling and monitoring practices among DOE facilities. The difference among the facilities exist in monitoring and sampling instrumentation, procedures, calibration, analytical methods, detection levels, and action levels. Many of these differences could be attributed to different operational needs.

  11. APPLICATION OF SEMIPERMEABLE MEMBRANE DEVICES TO INDOOR AIR SAMPLING

    EPA Science Inventory

    Semipermeable membrane devices (SPMDs) are a relatively new passive sampling technique for nonpolar organic compounds that have been extensively used for surface water sampling. A small body of literature indicates that SPMDs are also useful for air sampling. Because SPMDs ha...

  12. EML Surface Air Sampling Program, 1990--1993 data

    SciTech Connect

    Larsen, R.J.; Sanderson, C.G.; Kada, J.

    1995-11-01

    Measurements of the concentrations of specific atmospheric radionuclides in air filter samples collected for the Environmental Measurements Laboratory`s Surface Air Sampling Program (SASP) during 1990--1993, with the exception of April 1993, indicate that anthropogenic radionuclides, in both hemispheres, were at or below the lower limits of detection for the sampling and analytical techniques that were used to collect and measure them. The occasional detection of {sup 137}Cs in some air filter samples may have resulted from resuspension of previously deposited debris. Following the April 6, 1993 accident and release of radionuclides into the atmosphere at a reprocessing plant in the Tomsk-7 military nuclear complex located 16 km north of the Siberian city of Tomsk, Russia, weekly air filter samples from Barrow, Alaska; Thule, Greenland and Moosonee, Canada were selected for special analyses. The naturally occurring radioisotopes that the authors measure, {sup 7}Be and {sup 210}Pb, continue to be detected in most air filter samples. Variations in the annual mean concentrations of {sup 7}Be at many of the sites appear to result primarily from changes in the atmospheric production rate of this cosmogenic radionuclide. Short-term variations in the concentrations of {sup 7}Be and {sup 210}Pb continued to be observed at many sites at which weekly air filter samples were analyzed. The monthly gross gamma-ray activity and the monthly mean surface air concentrations of {sup 7}Be, {sup 95}Zr, {sup 137}Cs, {sup 144}Ce, and {sup 210}Pb measured at sampling sites in SASP during 1990--1993 are presented. The weekly mean surface air concentrations of {sup 7}Be, {sup 95}Zr, {sup 137}Cs, {sup 144}Ce, and {sup 210}Pb for samples collected during 1990--1993 are given for 17 sites.

  13. [Ambient and enclosed space air sampling for determination of contaminants].

    PubMed

    Dorogova, V B

    2010-01-01

    The paper touches upon the issues how to correctly and maximally take single and average daily samples of ambient, residential and public building, and enclosed space air for further tests for the content of hazardous substances. The paper is debated.

  14. A smart indoor air quality sensor network

    NASA Astrophysics Data System (ADS)

    Wen, Jin

    2006-03-01

    The indoor air quality (IAQ) has an important impact on public health. Currently, the indoor air pollution, caused by gas, particle, and bio-aerosol pollutants, is considered as the top five environmental risks to public health and has an estimated cost of $2 billion/year due to medical cost and lost productivity. Furthermore, current buildings are especially vulnerable for chemical and biological warfare (CBW) agent contamination because the central air conditioning and ventilation system serve as a nature carrier to spread the released agent from one location to the whole indoor environment within a short time period. To assure the IAQ and safety for either new or existing buildings, real time comprehensive IAQ and CBW measurements are needed. With the development of new sensing technologies, economic and reliable comprehensive IAQ and CBW sensors become promising. However, few studies exist that examine the design and evaluation issues related to IAQ and CBW sensor network. In this paper, relevant research areas including IAQ and CBW sensor development, demand control ventilation, indoor CBW sensor system design, and sensor system design for other areas such as water system protection, fault detection and diagnosis, are reviewed and summarized. Potential research opportunities for IAQ and CBW sensor system design and evaluation are discussed.

  15. Solid waste transuranic storage and assay facility indoor air sampling

    SciTech Connect

    Pingel, L.A., Westinghouse Hanford

    1996-08-20

    The purpose of the study is to collect and analyze samples of the indoor air at the Transuranic Storage and Assay Facility (TRUSAF), Westinghouse Hanford. A modified US EPA TO-14 methodology, using gas chromatography/mass spectrography, may be used for the collection and analysis of the samples. The information obtained will be used to estimate the total release of volatile organic compounds from TRUSAF to determine the need for air emmission permits.

  16. Representativeness of air quality monitoring networks

    NASA Astrophysics Data System (ADS)

    Duyzer, Jan; van den Hout, Dick; Zandveld, Peter; van Ratingen, Sjoerd

    2015-03-01

    The suitability of European networks to check compliance with air quality standards and to assess exposure of the population was investigated. An air quality model (URBIS) was applied to estimate and compare the spatial distribution of the concentration of nitrogen dioxide (NO2) in ambient air in four large cities. The concentrations calculated at the location of the monitoring stations, compared well with the concentrations measured at the stations indicating that the models worked well. Therefore the calculated concentration distributions were used as a proxy for the actual concentration distributions across the cities. The distributions of these proxy concentrations across the city populations was determined and cumulative population distribution curves were estimated. The calculated annual mean values at the monitoring network stations were located on the population distribution curves to estimate the fractions of the populations that the monitoring network stations represent. This macro scale procedure is used to evaluate which subgroups of the monitoring stations can be reliably used to decide on compliance or to estimate the concentration the population is exposed to. In addition, the CAR model and Computational Fluid Dynamics (CFD) models are used to investigate the effect of micro scale siting of the monitoring stations within the streets. The following observations were made: - Berlin and London networks cover the distribution of concentrations to which the population is exposed rather well, while Stuttgart and Barcelona have stations at sites with mainly the higher concentrations and the exposure is covered less well. - The networks in London and Berlin, with a substantial number of urban background stations, seem fit to monitor the average population exposure, contrary to those in Stuttgart and Barcelona with only a limited number of these stations. - The concentrations measured at street stations hardly reflect the calculated differences in street

  17. Concepts for Environmental Radioactive Air Sampling and Monitoring

    SciTech Connect

    Barnett, J. Matthew

    2011-11-04

    Environmental radioactive air sampling and monitoring is becoming increasingly important as regulatory agencies promulgate requirements for the measurement and quantification of radioactive contaminants. While researchers add to the growing body of knowledge in this area, events such as earthquakes and tsunamis demonstrate how nuclear systems can be compromised. The result is the need for adequate environmental monitoring to assure the public of their safety and to assist emergency workers in their response. Two forms of radioactive air monitoring include direct effluent measurements and environmental surveillance. This chapter presents basic concepts for direct effluent sampling and environmental surveillance of radioactive air emissions, including information on establishing the basis for sampling and/or monitoring, criteria for sampling media and sample analysis, reporting and compliance, and continual improvement.

  18. Journal Article: EPA's National Dioxin Air Monitoring Network ...

    EPA Pesticide Factsheets

    The U.S. Environmental Protection Agency (U.S. EPA) established the National Dioxin Air Monitoring Network (NDAMN) in June of 1998, and operated it until November of 2004. The objective of NDAMN was to determine background air concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs). NDAMN started with 10 sampling sites, adding more over time until the final count of 34 sites was reached by the beginning of 2003. Samples were taken quarterly, and the final sample count was 685. All samples were measured for 17 PCDD/PCDF congeners, 8 PCDD/PCDF homologue groups, and 7 dl-PCBs (note: 5 additional dl-PCBs were added for samples starting in the summer of 2002; 317 samples had measurements of 12 dl-PCBs). The overall average total toxic equivalent (TEQ) concentration in the United States was 11.2 fg TEQ m−3 with dl-PCBs contributing 0.8 fg TEQ m−3 (7%) to this total. The archetype dioxin and furan background air congener profile was seen in the survey averages and in most individual samples. This archetype profile is characterized by low and similar concentrations for tetra – through hexa PCDD/PCDF congeners, with elevations in four congeners – a hepta dioxin and furan congener, and both octa congeners. Sites were generally categorized as urban (4 sites), rural (23 sites), or remote (7 sites). The average TEQ concentrations over all sites and samples within these cat

  19. Journal Article: the National Dioxin Air Monitoring Network ...

    EPA Pesticide Factsheets

    The U.S. EPA has established a National Dioxin Air Monitoring Network (NDAMN) to determine the temporal and geographical variability of atmospheric CDDs, CDFs and coplanar PCBs at rural and nonimpacted locations throughout the United States. Currently operating at 32 sampling stations, NDAMN has three primary purposes: (1) to determine the atmospheric levels and occurrences of dioxin-like compounds in rural and agricultural areas where livestock, poultry and animal feed crops are grown; (2) to provide measurements of atmospheric levels of dioxin-like compounds in different geographic regions of the U.S.; and (3) to provide information regarding the long-range transport of dioxin-like compounds in air over the U.S. Designed in 1997, NDAMN has been implemented in phases, with the first phase consisting of 9 monitoring stations. Previously EPA has reported on the preliminary results of monitoring at 9 rural locations from June1998 through June 19991. The one-year measurement at the 9 stations indicated an annual mean TEQDF–WHO98 air concentration of 12 fg m-3. Since this reporting, NDAMN has been extended to include additional stations. The following is intended to be an update to this national monitoring effort. We are reporting the air monitoring results of 22 NDAMN stations operational over 9 sampling moments from June 1998 to December 1999. Fifteen stations are in rural areas, and 6 are located in National Parks. One station is located in suburban Wa

  20. Air samplings in a Campylobacter jejuni positive laying hen flock.

    PubMed

    Ahmed, Marwa Fawzy El Metwaly; Schulz, Jochen; Hartung, Joerg

    2013-01-01

    The air in laying hen houses contains high concentrations of airborne bacteria. The numbers of these bacteria can be influenced by the efficiency of the chosen sampling method. In the presented study, AGI-30 Impingers and the Coriolis(®)µ air Sampler were compared in terms of their efficiency in sampling aerobic mesophilic bacteria in a laying hen house. Measurements were conducted in a laying hen flock with high prevalences of C. jejuni in order to investigate if culturable cells of this organism can also be detected by the applied methods. Airborne dust was also analyzed for the presence of C. jejuni specific DNA to assess the possible occurrence of non-culturable C. jejuni in the hen house air. The numbers of mesophilic airborne bacteria ranged from 8 × 10(4) - 2 × 10(6) CFU/m(-3) when sampled using AGI-30 Impingers, and from 2 × 10(5) - 4 × 10(6) CFU/m -3 when sampled using a Coriolis(®)µ air Sampler. The concentrations detected simultaneously by both devices correlated well (rPearson = 0.755), but the Coriolis(®)µ air Sampler showed a significantly higher sampling efficiency (p<0.001). Although, the within flock prevalence of C. jejuni was high during the experiments (between 70-93%), neither of the air sampling methods could detect culturable C. jejuni from the air. However, C. jejuni specific DNA was detected in 15 out of 18 airborne dust samples by mapA PCR. Based on the results, it can be concluded that airborne culturable C. jejuni were not detectable, even with an efficient air sampler, because of their low concentration. Therefore, the risk of airborne infection to poultry workers on inhaling airborne C. jejuni seems negligible. Also, the transmission of culturable C. jejuni to neighboring farms by the airborne route is unlikely. Otherwise, the detection of airborne C. jejuni specific DNA suggests that non-culturable cells could appear in the hen house air, and in future it should be verified whether sampling stress of the air sampling methods

  1. Journal Article: the National Dioxin Air Monitoring Network ...

    EPA Pesticide Factsheets

    In June, 1998, the U.S. EPA established the National Dioxin Air Monitoring Network (NDAMN). The primary goal of NDAMN is determine the temporal and geographical variability of atmospheric CDDs, CDFs, and coplanar PCBs at rural and nonimpacted locations throughout the United States. Currently operating at 32 sampling stations, NDAMN has three primary purposes: (1) to determine the atmospheric levels and occurrences of dioxin-like compounds in rural and agricultural areas where livestock, poultry and animal feed crops are grown; (2) to provide measurements of atmospheric levels of dioxin-like compounds in different geographic regions of the U.S.; and (3) to provide information regarding the long-range transport of dioxin-like compounds in air over the U.S. At Dioxin 2000, we reported on the preliminary results of monitoring at 9 rural locations from June 1998 through June 1999. By the end of 1999, NDAMN had expanded to 21 sampling stations. Then, at Dioxin 2001, we reported the results of the first 18 months of operation of NDAMN at 15 rural and 6 National Park stations in the United States. The following is intended to be an update to this national monitoring effort. We are reporting the air monitoring results of 17 rural and 8 National Park NDAMN stations operational over 4 sampling moments during calendar year 2000. Two stations located in suburban Washington DC and San Francisco, CA are more urban in character and serve as an indicator of CDD/F and cop

  2. Analytical and experimental study on complex compressed air pipe network

    NASA Astrophysics Data System (ADS)

    Gai, Yushou; Cai, Maolin; Shi, Yan

    2015-09-01

    To analyze the working characteristics of complex compressed air networks, numerical methods are widely used which are based on finite element technology or intelligent algorithms. However, the effectiveness of the numerical methods is limited. In this paper, to provide a new method to optimize the design and the air supply strategy of the complex compressed air pipe network, firstly, a novel method to analyze the topology structure of the compressed air flow in the pipe network is initially proposed. A matrix is used to describe the topology structure of the compressed air flow. Moreover, based on the analysis of the pressure loss of the pipe network, the relationship between the pressure and the flow of the compressed air is derived, and a prediction method of pressure fluctuation and air flow in a segment in a complex pipe network is proposed. Finally, to inspect the effectiveness of the method, an experiment with a complex network is designed. The pressure and the flow of airflow in the network are measured and studied. The results of the study show that, the predicted results with the proposed method have a good consistency with the experimental results, and that verifies the air flow prediction method of the complex pipe network. This research proposes a new method to analyze the compressed air network and a prediction method of pressure fluctuation and air flow in a segment, which can predicate the fluctuation of the pressure according to the flow of compressed air, and predicate the fluctuation of the flow according to the pressure in a segment of a complex pipe network.

  3. Presence of organophosphorus pesticide oxygen analogs in air samples

    NASA Astrophysics Data System (ADS)

    Armstrong, Jenna L.; Fenske, Richard A.; Yost, Michael G.; Galvin, Kit; Tchong-French, Maria; Yu, Jianbo

    2013-02-01

    A number of recent toxicity studies have highlighted the increased potency of oxygen analogs (oxons) of several organophosphorus (OP) pesticides. These findings were a major concern after environmental oxons were identified in environmental samples from air and surfaces following agricultural spray applications in California and Washington State. This paper reports on the validity of oxygen analog measurements in air samples for the OP pesticide, chlorpyrifos. Controlled environmental and laboratory experiments were used to examine artificial formation of chlorpyrifos-oxon using OSHA Versatile Sampling (OVS) tubes as recommended by NIOSH method 5600. Additionally, we compared expected chlorpyrifos-oxon attributable to artificial transformation to observed chlorpyrifos-oxon in field samples from a 2008 Washington State Department of Health air monitoring study using non-parametric statistical methods. The amount of artificially transformed oxon was then modeled to determine the amount of oxon present in the environment. Toxicity equivalency factors (TEFs) for chlorpyrifos-oxon were used to calculate chlorpyrifos-equivalent air concentrations. The results demonstrate that the NIOSH-recommended sampling matrix (OVS tubes with XAD-2 resin) was found to artificially transform up to 30% of chlorpyrifos to chlorpyrifos-oxon, with higher percentages at lower concentrations (<30 ng m-3) typical of ambient or residential levels. Overall, the 2008 study data had significantly greater oxon than expected by artificial transformation, but the exact amount of environmental oxon in air remains difficult to quantify with the current sampling method. Failure to conduct laboratory analysis for chlorpyrifos-oxon may result in underestimation of total pesticide concentration when using XAD-2 resin matrices for occupational or residential sampling. Alternative methods that can accurately measure both OP pesticides and their oxygen analogs should be used for air sampling, and a toxicity

  4. A simple novel device for air sampling by electrokinetic capture

    DOE PAGES

    Gordon, Julian; Gandhi, Prasanthi; Shekhawat, Gajendra; ...

    2015-12-27

    A variety of different sampling devices are currently available to acquire air samples for the study of the microbiome of the air. All have a degree of technical complexity that limits deployment. Here, we evaluate the use of a novel device, which has no technical complexity and is easily deployable. An air-cleaning device powered by electrokinetic propulsion has been adapted to provide a universal method for collecting samples of the aerobiome. Plasma-induced charge in aerosol particles causes propulsion to and capture on a counter-electrode. The flow of ions creates net bulk airflow, with no moving parts. A device and electrodemore » assembly have been re-designed from air-cleaning technology to provide an average air flow of 120 lpm. This compares favorably with current air sampling devices based on physical air pumping. Capture efficiency was determined by comparison with a 0.4 μm polycarbonate reference filter, using fluorescent latex particles in a controlled environment chamber. Performance was compared with the same reference filter method in field studies in three different environments. For 23 common fungal species by quantitative polymerase chain reaction (qPCR), there was 100 % sensitivity and apparent specificity of 87%, with the reference filter taken as “gold standard.” Further, bacterial analysis of 16S RNA by amplicon sequencing showed equivalent community structure captured by the electrokinetic device and the reference filter. Unlike other current air sampling methods, capture of particles is determined by charge and so is not controlled by particle mass. We analyzed particle sizes captured from air, without regard to specific analyte by atomic force microscopy: particles at least as low as 100 nM could be captured from ambient air. This work introduces a very simple plug-and-play device that can sample air at a high-volume flow rate with no moving parts and collect particles down to the sub-micron range. In conclusion, the performance of

  5. A simple novel device for air sampling by electrokinetic capture

    SciTech Connect

    Gordon, Julian; Gandhi, Prasanthi; Shekhawat, Gajendra; Frazier, Angel; Hampton-Marcell, Jarrad; Gilbert, Jack A.

    2015-12-27

    A variety of different sampling devices are currently available to acquire air samples for the study of the microbiome of the air. All have a degree of technical complexity that limits deployment. Here, we evaluate the use of a novel device, which has no technical complexity and is easily deployable. An air-cleaning device powered by electrokinetic propulsion has been adapted to provide a universal method for collecting samples of the aerobiome. Plasma-induced charge in aerosol particles causes propulsion to and capture on a counter-electrode. The flow of ions creates net bulk airflow, with no moving parts. A device and electrode assembly have been re-designed from air-cleaning technology to provide an average air flow of 120 lpm. This compares favorably with current air sampling devices based on physical air pumping. Capture efficiency was determined by comparison with a 0.4 μm polycarbonate reference filter, using fluorescent latex particles in a controlled environment chamber. Performance was compared with the same reference filter method in field studies in three different environments. For 23 common fungal species by quantitative polymerase chain reaction (qPCR), there was 100 % sensitivity and apparent specificity of 87%, with the reference filter taken as “gold standard.” Further, bacterial analysis of 16S RNA by amplicon sequencing showed equivalent community structure captured by the electrokinetic device and the reference filter. Unlike other current air sampling methods, capture of particles is determined by charge and so is not controlled by particle mass. We analyzed particle sizes captured from air, without regard to specific analyte by atomic force microscopy: particles at least as low as 100 nM could be captured from ambient air. This work introduces a very simple plug-and-play device that can sample air at a high-volume flow rate with no moving parts and collect particles down to the sub-micron range. In conclusion, the performance of the

  6. [A membrane filter sampling method for determining microbial air pollution].

    PubMed

    Cherneva, P; Kiranova, A

    1996-01-01

    The method is a contribution in the evaluation of the exposition and the control of the standards for organic powders. The method concerns the sample-taking procedure and the analysis-making technique for determining of the concentration of the microbial pollution of the air. It is based on filtering of some amount of air through a membrane filter which is then processed for cultivating of microbial colonies on its surface. The results are obtained in number of microbial colonies per unit of air. The method presents opportunity to select and vary the filtered volume of air, to determine the respirable fraction, to determine the personal exposition, as well as for the simultaneous determining of the microbial pollution together with other important parameters of the particle pollutants of the air (metal, fibre and others).

  7. The U.S. Air Force Academy Falcon Telescope Network

    DTIC Science & Technology

    2014-09-01

    3048 The U.S. Air Force Academy Falcon Telescope Network Francis K. Chun, Roger D. Tippets, Michael E. Dearborn Department of Physics, U.S. Air...The Falcon Telescope Network (FTN) is a global network of small aperture telescopes developed by the Center for Space Situational Awareness...provides the equipment (e.g. telescope , mount, camera, filter wheel, dome, weather station, computers and storage devices) while the educational partners

  8. DUS II SOIL GAS SAMPLING AND AIR INJECTION TEST RESULTS

    SciTech Connect

    Noonkester, J.; Jackson, D.; Jones, W.; Hyde, W.; Kohn, J.; Walker, R.

    2012-09-20

    Soil vapor extraction (SVE) and air injection well testing was performed at the Dynamic Underground Stripping (DUS) site located near the M-Area Settling Basin (referred to as DUS II in this report). The objective of this testing was to determine the effectiveness of continued operation of these systems. Steam injection ended on September 19, 2009 and since this time the extraction operations have utilized residual heat that is present in the subsurface. The well testing campaign began on June 5, 2012 and was completed on June 25, 2012. Thirty-two (32) SVE wells were purged for 24 hours or longer using the active soil vapor extraction (ASVE) system at the DUS II site. During each test five or more soil gas samples were collected from each well and analyzed for target volatile organic compounds (VOCs). The DUS II site is divided into four parcels (see Figure 1) and soil gas sample results show the majority of residual VOC contamination remains in Parcel 1 with lesser amounts in the other three parcels. Several VOCs, including tetrachloroethylene (PCE) and trichloroethylene (TCE), were detected. PCE was the major VOC with lesser amounts of TCE. Most soil gas concentrations of PCE ranged from 0 to 60 ppmv with one well (VEW-22A) as high as 200 ppmv. Air sparging (AS) generally involves the injection of air into the aquifer through either vertical or horizontal wells. AS is coupled with SVE systems when contaminant recovery is necessary. While traditional air sparging (AS) is not a primary component of the DUS process, following the cessation of steam injection, eight (8) of the sixty-three (63) steam injection wells were used to inject air. These wells were previously used for hydrous pyrolysis oxidation (HPO) as part of the DUS process. Air sparging is different from the HPO operations in that the air was injected at a higher rate (20 to 50 scfm) versus HPO (1 to 2 scfm). . At the DUS II site the air injection wells were tested to determine if air sparging affected

  9. Radiological Air Sampling. Protocol Development for the Canadian Forces

    DTIC Science & Technology

    2003-03-01

    that filter must be removed from the sampler and counted by some method. If the efficiency of the radiation detector is D (in units of count rate per...unit activity), then the count rate R of the radiation detector will be R = CVFD. In practice, C is the unknown quantity. V is known from the sampling...Potential Solutions The problem, then, is that all air samples contain radon and thoron daughters that emit alpha, beta, and gamma radiation . Moreover

  10. Air sampling and analysis in a rubber vulcanization area.

    PubMed

    Rappaport, S M; Fraser, D A

    1977-05-01

    Results of sampling and analysis of air in a rubber vulcanization area are described. Organic compounds were collected on activated charcoal, desorbed with carbon disulfide and analyzed by gas chromatography. Several previously identified substances were quantitated, including styrene, toluene, ethylbenzene, and several oligomers of 1,3-butadiene. Concentrations ranged from 0.007 to 1.1 ppm.

  11. Air sampling of mold spores by slit impactors: yield comparison.

    PubMed

    Pityn, Peter J; Anderson, James

    2013-01-01

    The performance of simple slit impactors for air sampling of mold contamination was compared under field conditions. Samples were collected side-by-side, outdoors in quadruplicates with Burkhard (ambient sampler) and Allergenco MK3 spore traps and with two identical Allergenco slit cassettes operated at diverse flow rates of 5 and 15 L/min, respectively. The number and types of mold spores in each sample were quantified by microscopy. Results showed all four single-stage slit impactors produced similar spore yields. Moreover, paired slit cassettes produced similar outcomes despite a three-fold difference in their sampling rate. No measurable difference in the amount or mix of mold spores per m(3)of air was detected. The implications for assessment of human exposures and interpretation of indoor/outdoor fungal burden are discussed. These findings demonstrate that slit cassettes capture most small spores, effectively and without bias, when operated at a range of flow rates including the lower flow rates used for personal sampling. Our findings indicate sampling data for mold spores correlate for different single stage impactor collection methodologies and that data quality is not deteriorated by operating conditions deviating from manufacturers' norms allowing such sampling results to be used for scientific, legal, investigative, or property insurance purposes. The same conclusion may not be applied to other particle sampling instruments and mulit-stage impactors used for ambient particulate sampling, which represent an entirely different scenario. This knowledge may help facilitate comparison between scientific studies where methodological differences exist.

  12. Air quality monitor and acid rain networks

    NASA Technical Reports Server (NTRS)

    Rudolph, H.

    1980-01-01

    The air quality monitor program which consists of two permanent air monitor stations (PAMS's) and four mobile shuttle pollutant air monitor stations (SPAMS's) is evaluated. The PAMS measures SO sub X, NO sub X particulates, CO, O3, and nonmethane hydrocarbons. The SPAMS measures O3, SO2, HCl, and particulates. The collection and analysis of data in the rain monitor program are discussed.

  13. Lightweight simulation of air traffic control using simple temporal networks

    NASA Technical Reports Server (NTRS)

    Knight, Russell

    2005-01-01

    We provide a formulation of the air traffic control problem and a solver for this problem that makes use of temporal constraint networks and simple geometric reasoning. We provide results showing that this approach is practical for realistic simulated problems.

  14. Comparison of large networks with sub-sampling strategies

    NASA Astrophysics Data System (ADS)

    Ali, Waqar; Wegner, Anatol E.; Gaunt, Robert E.; Deane, Charlotte M.; Reinert, Gesine

    2016-07-01

    Networks are routinely used to represent large data sets, making the comparison of networks a tantalizing research question in many areas. Techniques for such analysis vary from simply comparing network summary statistics to sophisticated but computationally expensive alignment-based approaches. Most existing methods either do not generalize well to different types of networks or do not provide a quantitative similarity score between networks. In contrast, alignment-free topology based network similarity scores empower us to analyse large sets of networks containing different types and sizes of data. Netdis is such a score that defines network similarity through the counts of small sub-graphs in the local neighbourhood of all nodes. Here, we introduce a sub-sampling procedure based on neighbourhoods which links naturally with the framework of network comparisons through local neighbourhood comparisons. Our theoretical arguments justify basing the Netdis statistic on a sample of similar-sized neighbourhoods. Our tests on empirical and synthetic datasets indicate that often only 10% of the neighbourhoods of a network suffice for optimal performance, leading to a drastic reduction in computational requirements. The sampling procedure is applicable even when only a small sample of the network is known, and thus provides a novel tool for network comparison of very large and potentially incomplete datasets.

  15. Comparison of large networks with sub-sampling strategies

    PubMed Central

    Ali, Waqar; Wegner, Anatol E.; Gaunt, Robert E.; Deane, Charlotte M.; Reinert, Gesine

    2016-01-01

    Networks are routinely used to represent large data sets, making the comparison of networks a tantalizing research question in many areas. Techniques for such analysis vary from simply comparing network summary statistics to sophisticated but computationally expensive alignment-based approaches. Most existing methods either do not generalize well to different types of networks or do not provide a quantitative similarity score between networks. In contrast, alignment-free topology based network similarity scores empower us to analyse large sets of networks containing different types and sizes of data. Netdis is such a score that defines network similarity through the counts of small sub-graphs in the local neighbourhood of all nodes. Here, we introduce a sub-sampling procedure based on neighbourhoods which links naturally with the framework of network comparisons through local neighbourhood comparisons. Our theoretical arguments justify basing the Netdis statistic on a sample of similar-sized neighbourhoods. Our tests on empirical and synthetic datasets indicate that often only 10% of the neighbourhoods of a network suffice for optimal performance, leading to a drastic reduction in computational requirements. The sampling procedure is applicable even when only a small sample of the network is known, and thus provides a novel tool for network comparison of very large and potentially incomplete datasets. PMID:27380992

  16. DESIGN OF LARGE-SCALE AIR MONITORING NETWORKS

    EPA Science Inventory

    The potential effects of air pollution on human health have received much attention in recent years. In the U.S. and other countries, there are extensive large-scale monitoring networks designed to collect data to inform the public of exposure risks to air pollution. A major crit...

  17. RAPID SEPARATION METHOD FOR ACTINIDES IN EMERGENCY AIR FILTER SAMPLES

    SciTech Connect

    Maxwell, S.; Noyes, G.; Culligan, B.

    2010-02-03

    A new rapid method for the determination of actinides and strontium in air filter samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used in emergency response situations. The actinides and strontium in air filter method utilizes a rapid acid digestion method and a streamlined column separation process with stacked TEVA, TRU and Sr Resin cartridges. Vacuum box technology and rapid flow rates are used to reduce analytical time. Alpha emitters are prepared using cerium fluoride microprecipitation for counting by alpha spectrometry. The purified {sup 90}Sr fractions are mounted directly on planchets and counted by gas flow proportional counting. The method showed high chemical recoveries and effective removal of interferences. This new procedure was applied to emergency air filter samples received in the NRIP Emergency Response exercise administered by the National Institute for Standards and Technology (NIST) in April, 2009. The actinide and {sup 90}Sr in air filter results were reported in {approx}4 hours with excellent quality.

  18. Evaluation of membrane filter field monitors for microbiological air sampling

    NASA Technical Reports Server (NTRS)

    Fields, N. D.; Oxborrow, G. S.; Puleo, J. R.; Herring, C. M.

    1974-01-01

    Due to area constraints encountered in assembly and testing areas of spacecraft, the membrane filter field monitor (MF) and the National Aeronautics and Space Administration-accepted Reyniers slit air sampler were compared for recovery of airborne microbial contamination. The intramural air in a microbiological laboratory area and a clean room environment used for the assembly and testing of the Apollo spacecraft was studied. A significantly higher number of microorganisms was recovered by the Reyniers sampler. A high degree of consistency between the two sampling methods was shown by a regression analysis, with a correlation coefficient of 0.93. The MF samplers detected 79% of the concentration measured by the Reyniers slit samplers. The types of microorganisms identified from both sampling methods were similar.

  19. Results from the stable isotope sampling network in Carboeuroflux

    NASA Astrophysics Data System (ADS)

    Yakir, D.; Hemming, D.

    2002-12-01

    Integrating stable isotopic measurements of canopy air and ecosystem organics with flux tower and ecophysiological data provides a powerful tool to differentiate between carbon sources and sinks, and scale-up processes from plant to ecosystem levels. During the 2001 and 2002 growing-seasons monthly flask samples of nocturnal canopy air and ecosystem organics were collected from selected forest flux sites within the Carboeuroflux network (13 sites in 2001 and 18 in 2002). Flask air was analysed for CO2 concentration ([CO2]), and the carbon and oxygen isotopic compositions (δ13C and δ18O) of this CO2. The δ18O of waters distilled from leaf, stem and soil samples, and the δ13C and δ18O of these dried, homogonised organic samples were also measured. Analytical precisions were ñ0.1ppmv for [CO2], ñ0.1 permil and ñ0.2 permil for the δ13C and δ18O of atmospheric CO2, ñ0.05 permil for water δ18O and ñ0.1 permil for both the δ13C and δ18O of organics. The δ13C of ecosystem respired CO2 (δ13CR) was determined for each sampling period and location using a Keeling plot approach. Ecosystem discrimination (Δ13CE) was estimated as the difference between the δ13Cs of background atmospheric CO2 and ecosystem respired CO2. The seasonal and spatial variation in these variables, and the δ13C and δ18O compositions of the organic samples are examined relative to meteorological and ecophysiological conditions. We assessed the potential for using the δ18O of ecosystem respired CO2 (δ18OR) together with that of soil and leaf waters to partition between the soil and above-ground respired CO2 sources. At sites where soil δ13C varied significantly from leaf δ13C, we also assessed the partitioning potential in using the δ13C data. More intensive sampling campaigns, including incubations in branch-bags, and leaf, trunk and soil chambers, were also conducted at specific sites to examine the partitioning and scale relationships between individual source CO2 contributions

  20. Can car air filters be useful as a sampling medium for air pollution monitoring purposes?

    PubMed

    Katsoyiannis, Athanasios; Birgul, Askin; Ratola, Nuno; Cincinelli, Alessandra; Sweetman, Andy J; Jones, Kevin C

    2012-11-01

    Urban air quality and real human exposure to chemical environmental stressors is an issue of high scientific and political interest. In an effort to find innovative and inexpensive means for air quality monitoring, the ability of car engine air filters (CAFs) to act as efficient samplers collecting street level air, to which people are exposed to, was tested. In particular, in the case of taxis, air filters are replaced after regular distances, the itineraries are almost exclusively urban, cruising mode is similar and, thus, knowledge of the air flow can provide with an integrated city air sample. The present pilot study focused on polycyclic aromatic hydrocarbons (PAHs), the most important category of organic pollutants associated with traffic emissions. Concentrations of ΣPAHs in CAFs ranged between 650 and 2900 μg CAF(-1), with benzo[b]fluoranthene, benzo[k]fluoranthene and indeno[123-cd]pyrene being the most abundant PAHs. Benzo[a]pyrene (BaP) ranged between 110 and 250 μg CAF(-1), accounting regularly for 5-15% of the total carcinogenic PAHs. The CAF PAH loads were used to derive road-level atmospheric PAH concentrations from a standard formula relating to the CAF air flow. Important parameters/assumptions for these estimates are the cruising speed and the exposure duration of each CAF. Based on information obtained from the garage experts, an average 'sampled air volume' of 48,750 m(3) per CAF was estimated, with uncertainty in this calculation estimated to be about a factor of 4 between the two extreme scenarios. Based on this air volume, ΣPAHs ranged between 13 and 56 ng m(-3) and BaP between 2.1 and 5.0 ng m(-3), suggesting that in-traffic BaP concentrations can be many times higher than the limit values set by the UK (0.25 ng m(-3)) and the European Union (1.0 ng m(-3)), or from active sampling stations normally cited on building roof tops or far from city centres. Notwithstanding the limitations of this approach, the very low cost, the continuous

  1. Air Sampling Data for BP Spill/Deepwater Horizon

    EPA Pesticide Factsheets

    The Deepwater Horizon oil spill (also referred to as the BP oil spill) began on 20 April 2010 in the Gulf of Mexico on the BP-operated Macondo Prospect. Following the explosion and sinking of the Deepwater Horizon oil rig, a sea-floor oil gusher flowed for 87 days, until it was capped on 15 July 2010.In response to the BP oil spill, EPA sampled air, water, sediment, and waste generated by the cleanup operations.

  2. Artifact peroxides produced during cryogenic sampling of ambient air

    NASA Astrophysics Data System (ADS)

    Staffelbach, Thomas; Neftel, Albrecht; Dasgupta, Purnendu K.

    Peroxides were found to be produced as artifacts during cryogenic sampling with Horibe traps. Cryogenic trap sampling was compared to collection with a wet effluent diffusion denuder and a Nafion membrane diffusion denuder. Hydrogen peroxide and hydroxymethyl hydroperoxide measured in the cryogenic trap samples were significantly higher. In comparison, no evidence of artifact methyl hydroperoxide production was found. The amount of artifact H2O2 and HMHP produced increased with decreasing trap temperature. Spiking ambient air with ethene or isoprene showed that these hydrocarbons, in the presence of ozone, can be responsible for the artifact production of peroxides. Our results clearly suggest that the peroxide data obtained by cryogenic sampling and reported in the literature should be interpreted with caution.

  3. The use of Whatman-41 filters for high volume air sampling

    NASA Technical Reports Server (NTRS)

    Neustadter, H. E.; Sidik, S. M.; King, R. B.; Fordyce, J. S.; Burr, J. C.

    1975-01-01

    The feasibility of using W41 filter media on a routine TSP high-volume monitoring network was determined by comparison with glass fiber (GF) filtering. Results indicate that suspended particulate samples from GF filters averaged slightly, but not significantly, higher than those from Whatman-41 filters. Some extra handling procedures were required to avoid errors due to the hygroscopic nature of W41 filters; these added procedures are not overly burdensome, however, and they allow the performance of analytical work, thus extending the capabilities of high-volume sampling. It was demonstrated that W41 filters are practical for air quality monitoring and elemental analysis in environments similar to Cleveland's.

  4. The accelerated growth of the worldwide air transportation network

    NASA Astrophysics Data System (ADS)

    Azzam, Mark; Klingauf, Uwe; Zock, Alexander

    2013-01-01

    Mobility by means of air transportation has a critical impact on the global economy. Especially against the backdrop of further growth and an aggravation of the energy crisis, it is crucial to design a sustainable air transportation system. Current approaches focus on air traffic management. Nevertheless, also the historically evolved network offers great potential for an optimized redesign. But the understanding of its complex structure and development is limited, although modern network science supplies a great set of new methods and tools. So far studies analyzing air transportation as a complex network are based on divers and poor data, which are either merely regional or strongly bounded time-wise. As a result, the current state of research is rather inconsistent regarding topological coefficients and incomplete regarding network evolution. Therefore, we use the historical, worldwide OAG flight schedules data between 1979 and 2007 for our study. Through analyzing by far the most comprehensive data base so far, a better understanding of the network, its evolution and further implications is being provided. To our knowledge we present the first study to determine that the degree distribution of the worldwide air transportation network is non-stationary and is subject to densification and accelerated growth, respectively.

  5. Analysis of the Chinese provincial air transportation network

    NASA Astrophysics Data System (ADS)

    Du, Wen-Bo; Liang, Bo-Yuan; Hong, Chen; Lordan, Oriol

    2017-01-01

    The air transportation system is of a great impact on the economy and globalization of a country. In this paper, we analyze the Chinese air transportation network (ATN) from a provincial perspective via the complex network framework, where all airports located in one province are abstracted as a single node and flights between two provinces are denoted by a link. The results show that the network exhibits small-world property, homogeneous structure and disassortative mixing. The variation of the flight flow within 24 h is investigated and an obvious tide phenomenon is found in the dynamics of Chinese provincial ATN for high output level of tertiary industry. Our work will offer a novel approach for understanding the characteristic of the Chinese air transportation network.

  6. Personalized characterization of diseases using sample-specific networks

    PubMed Central

    Liu, Xiaoping; Wang, Yuetong; Ji, Hongbin; Aihara, Kazuyuki; Chen, Luonan

    2016-01-01

    A complex disease generally results not from malfunction of individual molecules but from dysfunction of the relevant system or network, which dynamically changes with time and conditions. Thus, estimating a condition-specific network from a single sample is crucial to elucidating the molecular mechanisms of complex diseases at the system level. However, there is currently no effective way to construct such an individual-specific network by expression profiling of a single sample because of the requirement of multiple samples for computing correlations. We developed here with a statistical method, i.e. a sample-specific network (SSN) method, which allows us to construct individual-specific networks based on molecular expressions of a single sample. Using this method, we can characterize various human diseases at a network level. In particular, such SSNs can lead to the identification of individual-specific disease modules as well as driver genes, even without gene sequencing information. Extensive analysis by using the Cancer Genome Atlas data not only demonstrated the effectiveness of the method, but also found new individual-specific driver genes and network patterns for various types of cancer. Biological experiments on drug resistance further validated one important advantage of our method over the traditional methods, i.e. we can even identify such drug resistance genes that actually have no clear differential expression between samples with and without the resistance, due to the additional network information. PMID:27596597

  7. Ambient Air Sampling During Quantum-dot Spray Deposition

    SciTech Connect

    Jankovic, John Timothy; Hollenbeck, Scott M

    2010-01-01

    Ambient air sampling for nano-size particle emissions was performed during spot spray coating operations with a Sono-Tek Exactacoat Benchtop system (ECB). The ECB consisted of the application equipment contained within an exhaust enclosure. The enclosure contained numerous small access openings, including an exhaust hook-up. Door access comprised most of the width and height of the front. The door itself was of the swing-out type. Two types of nanomaterials, Cadmium selenide (Cd-Se) quantum-dots (QDs) and Gold (Au) QDs, nominally 3.3 and 5 nm in diameter respectively, were applied during the evaluation. Median spray drop size was in the 20 to 60 micrometer size range.1 Surface coating tests were of short duration, on the order of one-half second per spray and ten spray applications between door openings. The enclosure was ventilated by connection to a high efficiency particulate aerosol (HEPA) filtered house exhaust system. The exhaust rate was nominally 80 ft3 per minute producing about 5 air changes per minute. Real time air monitoring with a scanning mobility particle size analyzer (SMPS ) with a size detection limit of 7 nm indicated a significant increase in the ambient air concentration upon early door opening. A handheld condensation particle counter (CPC) with a lower size limit of 10 nm did not record changes in the ambient background. This increase in the ambient was not observed when door opening was delayed for 2 minutes (~10 air changes). The ventilated enclosure controlled emissions except for cases of rapid door opening before the overspray could be removed by the exhaust. A time delay sufficient to provide 10 enclosure air changes (a concentration reduction of more than 99.99 %) before door opening prevented the release of aerosol particles in any size.2 Scanning-transmission electron microscopy (STEM) and atomic force microscopy (AFM) demonstrated the presence of agglomerates in the surfaces of the spray applied deposition. A filtered air sample of

  8. Sampling intercomparisons for aldehydes in simulated workplace air.

    PubMed

    Goelen, E; Lambrechts, M; Geyskens, F

    1997-05-01

    Thirty one laboratories of various EU Member States have participated in two interlaboratory comparisons in order to assess errors of personal sampling methods associated with both the sampling and the analytical steps. In contrast to conventional quality control schemes, this project particularly focuses attention on the sampling and identification step; it is executed by means of sampling exercises and has included discussions on potential sources of error. In a sampling exercise, participants come to a central facility and perform measurements on synthetic workplace air in a laboratory installation. Concentration levels of formaldehyde, acrolein, glutaraldehyde and acetaldehyde between 0.1 and 2 times the limit value for workplace air were prepared at various humidity levels and with acetone, occasionally, as interferent. Sampling times varied from 1-4 h. The related analytical work is performed at the analyst's own laboratory. The intention is for each participant to determine the observed value of the delivered standard atmosphere using the sampling method of his own choice. Trueness (bias), precision and relative overall uncertainty of each method-laboratory combination is calculated and verified towards compliance with EN 482, which outlines minimum performance criteria. The first challenge involved the precise gas phase generation of the selected analytes in high air flows (up to 300 1 min-1) and calculating the true value only by direct reference to primary standards. This was accomplished by modifying the capillary dosage injection technique so that reactive compounds, like low molecular mass aldehydes, could be dosed with the same accuracy and precision as unreactive solvents. A permeation tube with high emission rate was developed for formaldehyde. Up to ten different sampling techniques were evaluated. The measurement methods used by the majority of the participants were based on pumped sampling on silica cartridges (or tubes) and glass fiber filters

  9. Evaluation of official air sampling methodologies in Ukraine

    SciTech Connect

    Nakonechniy, J.J.; Wadden, R.A.; Scheff, P.A.; Suero, M.

    1997-12-31

    In conjunction with an environmental epidemiology study of the health of Ukrainian children, a significant amount of air pollution measurement data was gathered from government agencies. The areas of interest were the industrial city of Dneprodzherzhinsk; and the Dniprovsky region of Kyiv. The data were for 1993 and, for some of the monitoring stations, 1994. The pollutants reported included dust (approximately equivalent to TSP, total suspended particulate matter), SO{sub 2}, CO, NO{sub 2}, NO, H{sub 2}S, phenol, HCl, NH{sub 3}, formaldehyde, BaP, and lead. The ultimate goal was to evaluate whether existing historical data are appropriate for developing measures of human exposure. In order to evaluate the data it was necessary to understand the sampling and analytical methodologies which were used. Small sample volumes coupled with dated analytical procedures resulted in very poor precision and detection limits for most of the measured pollutants. The measurement of particulate matter is a good example of the limits imposed by the sampling methodology. The short sample time (20 min), small sample volume (150 lpm), and limited analytical balances (0.5 mg resolution) result in a minimum lower limit of detection of 0.25 mg/m{sup 3}. For example at Kyiv Station 3 in 1993, only one of 545 measurements exceeded 0.2 mg/m{sup 3}. This minimum detectable quantity is over three times the former US annual TSP standard. In addition, even when operated on a 24-hour basis in the US, it has been shown that the sampling method only collected approximately 34% of that collected by a co-located hi-vol sampler. Consequently, official air pollution data for suspended dust are likely to severely under-represent actual ambient concentrations. Data for other pollutants are presented and sampling and analytical methods are similarly compared with Western methods in common use.

  10. Passive air sampling of gaseous elemental mercury: a critical review

    NASA Astrophysics Data System (ADS)

    McLagan, David S.; Mazur, Maxwell E. E.; Mitchell, Carl P. J.; Wania, Frank

    2016-03-01

    Because gaseous elemental mercury (GEM) is distributed globally through the atmosphere, reliable means of measuring its concentrations in air are important. Passive air samplers (PASs), designed to be cheap, simple to operate, and to work without electricity, could provide an alternative to established active sampling techniques in applications such as (1) long-term monitoring of atmospheric GEM levels in remote regions and in developing countries, (2) atmospheric mercury source identification and characterization through finely resolved spatial mapping, and (3) the recording of personal exposure to GEM. An effective GEM PAS requires a tightly constrained sampling rate, a large and stable uptake capacity, and a sensitive analytical technique. None of the GEM PASs developed to date achieve levels of accuracy and precision sufficient for the reliable determination of background concentrations over extended deployments. This is due to (1) sampling rates that vary due to meteorological factors and manufacturing inconsistencies, and/or (2) an often low, irreproducible and/or unstable uptake capacity of the employed sorbents. While we identify shortcomings of existing GEM PAS, we also reveal potential routes to overcome those difficulties. Activated carbon and nanostructured metal surfaces hold promise as effective sorbents. Sampler designs incorporating diffusive barriers should be able to notably reduce the influence of wind on sampling rates.

  11. Passive air sampling of gaseous elemental mercury: a critical review

    NASA Astrophysics Data System (ADS)

    McLagan, D. S.; Mazur, M. E. E.; Mitchell, C. P. J.; Wania, F.

    2015-12-01

    Because gaseous elemental mercury (GEM) is distributed globally through the atmosphere, reliable means of measuring its concentrations in air are important. Passive air samplers (PASs), designed to be cheap, simple to operate, and to work without electricity, could provide an alternative to established active sampling techniques in applications such as (1) long term monitoring of atmospheric GEM levels in remote regions and in developing countries, (2) atmospheric mercury source identification and characterisation through finely-resolved spatial mapping, and (3) the recording of personal exposure to GEM. An effective GEM PAS requires a tightly constrained sampling rate, a large and stable uptake capacity, and a sensitive analytical technique. None of the GEM PASs developed to date achieves levels of accuracy and precision sufficient for the reliable determination of background concentrations over extended deployments. This is due to (1) sampling rates that vary due to meteorological factors and manufacturing inconsistencies and/or (2) an often low, irreproducible and/or unstable uptake capacity of the employed sorbents. While we identify shortcomings of existing GEM PAS, we also reveal potential routes to overcome those difficulties. Activated carbon and nano-structured metal surfaces hold promise as effective sorbents. Sampler designs incorporating diffusive barriers should be able to notably reduce the influence of wind on sampling rates.

  12. Sampling rare switching events in biochemical networks.

    PubMed

    Allen, Rosalind J; Warren, Patrick B; Ten Wolde, Pieter Rein

    2005-01-14

    Bistable biochemical switches are widely found in gene regulatory networks and signal transduction pathways. Their switching dynamics are difficult to study, however, because switching events are rare, and the systems are out of equilibrium. We present a simulation method for predicting the rate and mechanism of the flipping of these switches. We apply it to a genetic switch and find that it is highly efficient. The path ensembles for the forward and reverse processes do not coincide. The method is widely applicable to rare events and nonequilibrium processes.

  13. PRECISION OF ATMOSPHERIC DRY DEPOSITION DATA FROM THE CLEAN AIR STATUS AND TRENDS NETWORK (CASTNET)

    EPA Science Inventory

    A collocated, dry deposition sampling program was begun in January 1987 by the US Environmental Protection Agency to provide ongoing estimates of the overall precision of dry deposition and supporting data entering the Clean Air Status and Trends Network (CASTNet) archives Duplic...

  14. Chemical transformations during ambient air sampling for organic vapors

    SciTech Connect

    Pellizzari, E.D.; Drost, K.J.

    1984-09-01

    Potential chemical transformations of olefins in the presence of ozone and high levels (ppm) of halogens (Cl/sub 2/, Br/sub 2/) were demonstrated when sampling ambient air with a sorbent cartridge. The use of stryene-d/sub 8/ and cyclohexene-d/sub 10/ spiked sampling devices and capillary gas chromatography/mass spectrometry (GC/MS) analysis allowed the detection and identification of several deuteriated oxidation and halogenated products. Dimethylamine-d/sub 6/ was converted in trace quantities (5-10 mg) to dimethylnitrosamine-d/sub 6/ when sampling was conducted in the presence of NO/sub x/. Oxidation reactions were prevented when filters (2.5 cm) employed for removing particulates were impregnated with 5-10 mg of sodium thiosulfate and placed in front of the sorbent cartridge. Halogenation reactions were also consideraly reduced.

  15. Implementation of Fowler's method for end-tidal air sampling.

    PubMed

    Di Francesco, F; Loccioni, C; Fioravanti, M; Russo, A; Pioggia, G; Ferro, M; Roehrer, I; Tabucchi, S; Onor, M

    2008-09-01

    The design, realization and testing of a CO(2)-triggered breath sampler, capable of a separate collection of dead space and end-tidal air on multiple breaths, is presented. This sampling procedure has advantages in terms of the sample volume, insights regarding the origin of compounds, increased reproducibility and higher concentrations of compounds. The high quality of design and the speed of the components ensure a breath-by-breath estimate of dead volume, as well as the comfort and safety of the subject under test. The system represents a valid tool to contribute to the development of a standardized sampling protocol needed to compare results obtained by the various groups in this field.

  16. Analysis of the Chinese air route network as a complex network

    NASA Astrophysics Data System (ADS)

    Cai, Kai-Quan; Zhang, Jun; Du, Wen-Bo; Cao, Xian-Bin

    2012-02-01

    The air route network, which supports all the flight activities of the civil aviation, is the most fundamental infrastructure of air traffic management system. In this paper, we study the Chinese air route network (CARN) within the framework of complex networks. We find that CARN is a geographical network possessing exponential degree distribution, low clustering coefficient, large shortest path length and exponential spatial distance distribution that is obviously different from that of the Chinese airport network (CAN). Besides, via investigating the flight data from 2002 to 2010, we demonstrate that the topology structure of CARN is homogeneous, howbeit the distribution of flight flow on CARN is rather heterogeneous. In addition, the traffic on CARN keeps growing in an exponential form and the increasing speed of west China is remarkably larger than that of east China. Our work will be helpful to better understand Chinese air traffic systems.

  17. Network Sampling and Classification:An Investigation of Network Model Representations

    PubMed Central

    Airoldi, Edoardo M.; Bai, Xue; Carley, Kathleen M.

    2011-01-01

    Methods for generating a random sample of networks with desired properties are important tools for the analysis of social, biological, and information networks. Algorithm-based approaches to sampling networks have received a great deal of attention in recent literature. Most of these algorithms are based on simple intuitions that associate the full features of connectivity patterns with specific values of only one or two network metrics. Substantive conclusions are crucially dependent on this association holding true. However, the extent to which this simple intuition holds true is not yet known. In this paper, we examine the association between the connectivity patterns that a network sampling algorithm aims to generate and the connectivity patterns of the generated networks, measured by an existing set of popular network metrics. We find that different network sampling algorithms can yield networks with similar connectivity patterns. We also find that the alternative algorithms for the same connectivity pattern can yield networks with different connectivity patterns. We argue that conclusions based on simulated network studies must focus on the full features of the connectivity patterns of a network instead of on the limited set of network metrics for a specific network type. This fact has important implications for network data analysis: for instance, implications related to the way significance is currently assessed. PMID:21666773

  18. Finite-sample based learning algorithms for feedforward networks

    SciTech Connect

    Rao, N.S.V.; Protopopescu, V.; Mann, R.C.; Oblow, E.M.; Iyengar, S.S.

    1995-04-01

    We discuss two classes of convergent algorithms for learning continuous functions (and also regression functions) that are represented by FeedForward Networks (FFN). The first class of algorithms, applicable to networks with unknown weights located only in the output layer, is obtained by utilizing the potential function methods of Aizerman et al. The second class, applicable to general feedforward networks, is obtained by utilizing the classical Robbins-Monro style stochastic approximation methods. Conditions relating the sample sizes to the error bounds are derived for both classes of algorithms using martingale-type inequalities. For concreteness, the discussion is presented in terms of neural networks, but the results are applicable to general feedforward networks, in particular to wavelet networks. The algorithms can also be directly applied to concept learning problems. A main distinguishing feature of the this work is that the sample sizes are based on explicit algorithms rather than information-based methods.

  19. Landscape Characterization and Representativeness Analysis for Understanding Sampling Network Coverage

    SciTech Connect

    Maddalena, Damian; Hoffman, Forrest; Kumar, Jitendra; Hargrove, William

    2014-08-01

    Sampling networks rarely conform to spatial and temporal ideals, often comprised of network sampling points which are unevenly distributed and located in less than ideal locations due to access constraints, budget limitations, or political conflict. Quantifying the global, regional, and temporal representativeness of these networks by quantifying the coverage of network infrastructure highlights the capabilities and limitations of the data collected, facilitates upscaling and downscaling for modeling purposes, and improves the planning efforts for future infrastructure investment under current conditions and future modeled scenarios. The work presented here utilizes multivariate spatiotemporal clustering analysis and representativeness analysis for quantitative landscape characterization and assessment of the Fluxnet, RAINFOR, and ForestGEO networks. Results include ecoregions that highlight patterns of bioclimatic, topographic, and edaphic variables and quantitative representativeness maps of individual and combined networks.

  20. Sampling and noise in vision networks

    NASA Technical Reports Server (NTRS)

    Ahumada, Albert J., Jr.

    1990-01-01

    This research is part of the Human Interface Research Branch-Vision Group's program to develop computable models of biological solutions to general vision system problems. Two problem areas are addressed: effects of discrete sampling by receptors, and effects of visual system noise.

  1. Interferometrically stable, enclosed, spinning sample cell for spectroscopic experiments on air-sensitive samples

    NASA Astrophysics Data System (ADS)

    Baranov, Dmitry; Hill, Robert J.; Ryu, Jisu; Park, Samuel D.; Huerta-Viga, Adriana; Carollo, Alexa R.; Jonas, David M.

    2017-01-01

    In experiments with high photon flux, it is necessary to rapidly remove the sample from the beam and to delay re-excitation until the sample has returned to equilibrium. Rapid and complete sample exchange has been a challenge for air-sensitive samples and for vibration-sensitive experiments. Here, a compact spinning sample cell for air and moisture sensitive liquid and thin film samples is described. The principal parts of the cell are a copper gasket sealed enclosure, a 2.5 in. hard disk drive motor, and a reusable, chemically inert glass sandwich cell. The enclosure provides an oxygen and water free environment at the 1 ppm level, as demonstrated by multi-day tests with sodium benzophenone ketyl radical. Inside the enclosure, the glass sandwich cell spins at ≈70 Hz to generate tangential speeds of 7-12 m/s that enable complete sample exchange at 100 kHz repetition rates. The spinning cell is acoustically silent and compatible with a ±1 nm rms displacement stability interferometer. In order to enable the use of the spinning cell, we discuss centrifugation and how to prevent it, introduce the cycle-averaged resampling rate to characterize repetitive excitation, and develop a figure of merit for a long-lived photoproduct buildup.

  2. Interferometrically stable, enclosed, spinning sample cell for spectroscopic experiments on air-sensitive samples.

    PubMed

    Baranov, Dmitry; Hill, Robert J; Ryu, Jisu; Park, Samuel D; Huerta-Viga, Adriana; Carollo, Alexa R; Jonas, David M

    2017-01-01

    In experiments with high photon flux, it is necessary to rapidly remove the sample from the beam and to delay re-excitation until the sample has returned to equilibrium. Rapid and complete sample exchange has been a challenge for air-sensitive samples and for vibration-sensitive experiments. Here, a compact spinning sample cell for air and moisture sensitive liquid and thin film samples is described. The principal parts of the cell are a copper gasket sealed enclosure, a 2.5 in. hard disk drive motor, and a reusable, chemically inert glass sandwich cell. The enclosure provides an oxygen and water free environment at the 1 ppm level, as demonstrated by multi-day tests with sodium benzophenone ketyl radical. Inside the enclosure, the glass sandwich cell spins at ≈70 Hz to generate tangential speeds of 7-12 m/s that enable complete sample exchange at 100 kHz repetition rates. The spinning cell is acoustically silent and compatible with a ±1 nm rms displacement stability interferometer. In order to enable the use of the spinning cell, we discuss centrifugation and how to prevent it, introduce the cycle-averaged resampling rate to characterize repetitive excitation, and develop a figure of merit for a long-lived photoproduct buildup.

  3. Why social network analysis is important to Air Force applications

    NASA Astrophysics Data System (ADS)

    Havig, Paul R.; McIntire, John P.; Geiselman, Eric; Mohd-Zaid, Fairul

    2012-06-01

    Social network analysis is a powerful tool used to help analysts discover relationships amongst groups of people as well as individuals. It is the mathematics behind such social networks as Facebook and MySpace. These networks alone cause a huge amount of data to be generated and the issue is only compounded once one adds in other electronic media such as e-mails and twitter. In this paper we outline the basics of social network analysis and how it may be used in current and future Air Force applications.

  4. BOREAS AFM-5 Level-1 Upper Air Network Data

    NASA Technical Reports Server (NTRS)

    Barr, Alan; Hrynkiw, Charmaine; Newcomer, Jeffrey A. (Editor); Hall, Forrest G. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-5 team collected and processed data from the numerous radiosonde flights during the project. The goals of the AFM-05 team were to provide large-scale definition of the atmosphere by supplementing the existing Atmospheric Environment Service (AES) aerological network, both temporally and spatially. This data set includes basic upper-air parameters collected from the network of upper-air stations during the 1993, 1994, and 1996 field campaigns over the entire study region. The data are contained in tabular ASCII files. The level-1 upper-air network data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files also are available on a CD-ROM (see document number 20010000884).

  5. ENVIRONMENTAL SAMPLING USING LOCATION SPECIFIC AIR MONITORING IN BULK HANDLING FACILITIES

    SciTech Connect

    Sexton, L.; Hanks, D.; Degange, J.; Brant, H.; Hall, G.; Cable-Dunlap, P.; Anderson, B.

    2011-06-07

    Since the introduction of safeguards strengthening measures approved by the International Atomic Energy Agency (IAEA) Board of Governors (1992-1997), international nuclear safeguards inspectors have been able to utilize environmental sampling (ES) (e.g. deposited particulates, air, water, vegetation, sediments, soil and biota) in their safeguarding approaches at bulk uranium/plutonium handling facilities. Enhancements of environmental sampling techniques used by the IAEA in drawing conclusions concerning the absence of undeclared nuclear materials or activities will soon be able to take advantage of a recent step change improvement in the gathering and analysis of air samples at these facilities. Location specific air monitoring feasibility tests have been performed with excellent results in determining attribute and isotopic composition of chemical elements present in an actual test-bed sample. Isotopic analysis of collected particles from an Aerosol Contaminant Extractor (ACE) collection, was performed with the standard bulk sampling protocol used throughout the IAEA network of analytical laboratories (NWAL). The results yielded bulk isotopic values expected for the operations. Advanced designs of air monitoring instruments such as the ACE may be used in gas centrifuge enrichment plants (GCEP) to detect the production of highly enriched uranium (HEU) or enrichments not declared by a State. Researchers at Savannah River National Laboratory in collaboration with Oak Ridge National Laboratory are developing the next generation of ES equipment for air grab and constant samples that could become an important addition to the international nuclear safeguards inspector's toolkit. Location specific air monitoring to be used to establish a baseline environmental signature of a particular facility employed for comparison of consistencies in declared operations will be described in this paper. Implementation of air monitoring will be contrasted against the use of smear ES

  6. Ozone measurement system for NASA global air sampling program

    NASA Technical Reports Server (NTRS)

    Tiefermann, M. W.

    1979-01-01

    The ozone measurement system used in the NASA Global Air Sampling Program is described. The system uses a commercially available ozone concentration monitor that was modified and repackaged so as to operate unattended in an aircraft environment. The modifications required for aircraft use are described along with the calibration techniques, the measurement of ozone loss in the sample lines, and the operating procedures that were developed for use in the program. Based on calibrations with JPL's 5-meter ultraviolet photometer, all previously published GASP ozone data are biased high by 9 percent. A system error analysis showed that the total system measurement random error is from 3 to 8 percent of reading (depending on the pump diaphragm material) or 3 ppbv, whichever are greater.

  7. Network Structure and Biased Variance Estimation in Respondent Driven Sampling.

    PubMed

    Verdery, Ashton M; Mouw, Ted; Bauldry, Shawn; Mucha, Peter J

    2015-01-01

    This paper explores bias in the estimation of sampling variance in Respondent Driven Sampling (RDS). Prior methodological work on RDS has focused on its problematic assumptions and the biases and inefficiencies of its estimators of the population mean. Nonetheless, researchers have given only slight attention to the topic of estimating sampling variance in RDS, despite the importance of variance estimation for the construction of confidence intervals and hypothesis tests. In this paper, we show that the estimators of RDS sampling variance rely on a critical assumption that the network is First Order Markov (FOM) with respect to the dependent variable of interest. We demonstrate, through intuitive examples, mathematical generalizations, and computational experiments that current RDS variance estimators will always underestimate the population sampling variance of RDS in empirical networks that do not conform to the FOM assumption. Analysis of 215 observed university and school networks from Facebook and Add Health indicates that the FOM assumption is violated in every empirical network we analyze, and that these violations lead to substantially biased RDS estimators of sampling variance. We propose and test two alternative variance estimators that show some promise for reducing biases, but which also illustrate the limits of estimating sampling variance with only partial information on the underlying population social network.

  8. Network Structure and Biased Variance Estimation in Respondent Driven Sampling

    PubMed Central

    Verdery, Ashton M.; Mouw, Ted; Bauldry, Shawn; Mucha, Peter J.

    2015-01-01

    This paper explores bias in the estimation of sampling variance in Respondent Driven Sampling (RDS). Prior methodological work on RDS has focused on its problematic assumptions and the biases and inefficiencies of its estimators of the population mean. Nonetheless, researchers have given only slight attention to the topic of estimating sampling variance in RDS, despite the importance of variance estimation for the construction of confidence intervals and hypothesis tests. In this paper, we show that the estimators of RDS sampling variance rely on a critical assumption that the network is First Order Markov (FOM) with respect to the dependent variable of interest. We demonstrate, through intuitive examples, mathematical generalizations, and computational experiments that current RDS variance estimators will always underestimate the population sampling variance of RDS in empirical networks that do not conform to the FOM assumption. Analysis of 215 observed university and school networks from Facebook and Add Health indicates that the FOM assumption is violated in every empirical network we analyze, and that these violations lead to substantially biased RDS estimators of sampling variance. We propose and test two alternative variance estimators that show some promise for reducing biases, but which also illustrate the limits of estimating sampling variance with only partial information on the underlying population social network. PMID:26679927

  9. REVIEW OF THE RADNET AIR MONITORING NETWORK ...

    EPA Pesticide Factsheets

    RadNet, formerly known as ERAMS, has been operating since the 1970's, monitoring environmental radiation across the country, supporting responses to radiological emergencies, and providing important information on background levels of radiation in the environment. The original purpose of the system was to monitor fallout from weapons testing. Even though upgrades to and reconfiguration of the system have been planned for some time, the events of 9/11/01 gave impetus to a thorough upgrade of RadNet, primarily directed at providing more timely data and covering a larger portion of the nation's population. Moreover, the demands upon RadNet are now based upon homeland security support in addition to existing EPA monitoring responsibilities. Beginning in FY05 and continuing into FY13 up to135 near real-time air monitors will be put into operation across the country to provide decision making-data to EPA officials. Data will be transmitted from the monitors in all 50 states to a central database at the National Air and Radiation Environmental Laboratory (NAREL) in Montgomery, Alabama. The data will then be assessed and verified and made available to federal and state officials and, eventually, the public. A data flow model is being constructed to provide the most effective and efficient use of verified data obtained from the new radNet system The objective of the near-real time air monitoring component of RadNet is to provide verified decision-making data to fed

  10. Learning algorithms for feedforward networks based on finite samples

    SciTech Connect

    Rao, N.S.V.; Protopopescu, V.; Mann, R.C.; Oblow, E.M.; Iyengar, S.S.

    1994-09-01

    Two classes of convergent algorithms for learning continuous functions (and also regression functions) that are represented by feedforward networks, are discussed. The first class of algorithms, applicable to networks with unknown weights located only in the output layer, is obtained by utilizing the potential function methods of Aizerman et al. The second class, applicable to general feedforward networks, is obtained by utilizing the classical Robbins-Monro style stochastic approximation methods. Conditions relating the sample sizes to the error bounds are derived for both classes of algorithms using martingale-type inequalities. For concreteness, the discussion is presented in terms of neural networks, but the results are applicable to general feedforward networks, in particular to wavelet networks. The algorithms can be directly adapted to concept learning problems.

  11. 32 CFR 806.27 - Samples of Air Force FOIA processing documents.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Samples of Air Force FOIA processing documents. 806.27 Section 806.27 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ADMINISTRATION AIR FORCE FREEDOM OF INFORMATION ACT PROGRAM § 806.27 Samples of Air Force FOIA...

  12. 32 CFR 806.27 - Samples of Air Force FOIA processing documents.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Samples of Air Force FOIA processing documents. 806.27 Section 806.27 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ADMINISTRATION AIR FORCE FREEDOM OF INFORMATION ACT PROGRAM § 806.27 Samples of Air Force FOIA...

  13. 32 CFR 806.27 - Samples of Air Force FOIA processing documents.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Samples of Air Force FOIA processing documents. 806.27 Section 806.27 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ADMINISTRATION AIR FORCE FREEDOM OF INFORMATION ACT PROGRAM § 806.27 Samples of Air Force FOIA...

  14. A design methodology for evolutionary air transportation networks

    NASA Astrophysics Data System (ADS)

    Yang, Eunsuk

    The air transportation demand at large hubs in the U.S. is anticipated to double in the near future. Current runway construction plans at selected airports can relieve some capacity and delay problems, but many are doubtful that this solution is sufficient to accommodate the anticipated demand growth in the National Airspace System (NAS). With the worsening congestion problem, it is imperative to seek alternative solutions other than costly runway constructions. In this respect, many researchers and organizations have been building models and performing analyses of the NAS. However, the complexity and size of the problem results in an overwhelming task for transportation system modelers. This research seeks to compose an active design algorithm for an evolutionary airline network model so as to include network specific control properties. An airline network designer, referred to as a network architect, can use this tool to assess the possibilities of gaining more capacity by changing the network configuration. Since the Airline Deregulation Act of 1978, the airline service network has evolved into a distinct Hub-and-Spoke (H&S) network. Enplanement demand on the H&S network is the sum of Origin-Destination (O-D) demand and transfer demand. Even though the flight or enplanement demand is a function of O-D demand and passenger routings on the airline network, the distinction between enplanement and O-D demand is not often made. Instead, many demand forecast practices in current days are based on scale-ups from the enplanements, which include the demand to and from transferring network hubs. Based on this research, it was found that the current demand prediction practice can be improved by dissecting enplanements further into smaller pieces of information. As a result, enplanement demand is decomposed into intrinsic and variable parts. The proposed intrinsic demand model is based on the concept of 'true' O-D demand which includes the direction of each round trip

  15. A Framework for Dimensioning VDL-2 Air-Ground Networks

    NASA Technical Reports Server (NTRS)

    Ribeiro, Leila Z.; Monticone, Leone C.; Snow, Richard E.; Box, Frank; Apaza, Rafel; Bretmersky, Steven

    2014-01-01

    This paper describes a framework developed at MITRE for dimensioning a Very High Frequency (VHF) Digital Link Mode 2 (VDL-2) Air-to-Ground network. This framework was developed to support the FAA's Data Communications (Data Comm) program by providing estimates of expected capacity required for the air-ground network services that will support Controller-Pilot-Data-Link Communications (CPDLC), as well as the spectrum needed to operate the system at required levels of performance. The Data Comm program is part of the FAA's NextGen initiative to implement advanced communication capabilities in the National Airspace System (NAS). The first component of the framework is the radio-frequency (RF) coverage design for the network ground stations. Then we proceed to describe the approach used to assess the aircraft geographical distribution and the data traffic demand expected in the network. The next step is the resource allocation utilizing optimization algorithms developed in MITRE's Spectrum ProspectorTM tool to propose frequency assignment solutions, and a NASA-developed VDL-2 tool to perform simulations and determine whether a proposed plan meets the desired performance requirements. The framework presented is capable of providing quantitative estimates of multiple variables related to the air-ground network, in order to satisfy established coverage, capacity and latency performance requirements. Outputs include: coverage provided at different altitudes; data capacity required in the network, aggregated or on a per ground station basis; spectrum (pool of frequencies) needed for the system to meet a target performance; optimized frequency plan for a given scenario; expected performance given spectrum available; and, estimates of throughput distributions for a given scenario. We conclude with a discussion aimed at providing insight into the tradeoffs and challenges identified with respect to radio resource management for VDL-2 air-ground networks.

  16. Sample size and power considerations in network meta-analysis

    PubMed Central

    2012-01-01

    Background Network meta-analysis is becoming increasingly popular for establishing comparative effectiveness among multiple interventions for the same disease. Network meta-analysis inherits all methodological challenges of standard pairwise meta-analysis, but with increased complexity due to the multitude of intervention comparisons. One issue that is now widely recognized in pairwise meta-analysis is the issue of sample size and statistical power. This issue, however, has so far only received little attention in network meta-analysis. To date, no approaches have been proposed for evaluating the adequacy of the sample size, and thus power, in a treatment network. Findings In this article, we develop easy-to-use flexible methods for estimating the ‘effective sample size’ in indirect comparison meta-analysis and network meta-analysis. The effective sample size for a particular treatment comparison can be interpreted as the number of patients in a pairwise meta-analysis that would provide the same degree and strength of evidence as that which is provided in the indirect comparison or network meta-analysis. We further develop methods for retrospectively estimating the statistical power for each comparison in a network meta-analysis. We illustrate the performance of the proposed methods for estimating effective sample size and statistical power using data from a network meta-analysis on interventions for smoking cessation including over 100 trials. Conclusion The proposed methods are easy to use and will be of high value to regulatory agencies and decision makers who must assess the strength of the evidence supporting comparative effectiveness estimates. PMID:22992327

  17. Wide Area Recovery and Resilency Program (WARRP). Video - Aggressive Air Sampling for B. anthracis Spores

    DTIC Science & Technology

    2012-09-14

    34Systematic Evaluation of Aggressive Air Sampling for Bacillus anthracis Spores", in which aggressive air sampling, used for asbestos fiber detection, was...Sep 2012 Final 01 Feb 2011 - 01 Sep 2012 Wide Area Recovery and Resiliency Program (WARRP) Video - Aggressive Air Sampling for B. anthracis Spores

  18. A soil sampling intercomparison exercise for the ALMERA network.

    PubMed

    Belli, Maria; de Zorzi, Paolo; Sansone, Umberto; Shakhashiro, Abduhlghani; Gondin da Fonseca, Adelaide; Trinkl, Alexander; Benesch, Thomas

    2009-11-01

    Soil sampling and analysis for radionuclides after an accidental or routine release is a key factor for the dose calculation to members of the public, and for the establishment of possible countermeasures. The IAEA organized for selected laboratories of the ALMERA (Analytical Laboratories for the Measurement of Environmental Radioactivity) network a Soil Sampling Intercomparison Exercise (IAEA/SIE/01) with the objective of comparing soil sampling procedures used by different laboratories. The ALMERA network is a world-wide network of analytical laboratories located in IAEA member states capable of providing reliable and timely analysis of environmental samples in the event of an accidental or intentional release of radioactivity. Ten ALMERA laboratories were selected to participate in the sampling exercise. The soil sampling intercomparison exercise took place in November 2005 in an agricultural area qualified as a "reference site", aimed at assessing the uncertainties associated with soil sampling in agricultural, semi-natural, urban and contaminated environments and suitable for performing sampling intercomparison. In this paper, the laboratories sampling performance were evaluated.

  19. An Autosampler and Field Sample Carrier for Maximizing Throughput Using an Open-Air, Surface Sampling Ion Source for MS

    EPA Science Inventory

    A recently developed, commercially available, open-air, surface sampling ion source for mass spectrometers provides individual analyses in several seconds. To realize its full throughput potential, an autosampler and field sample carrier were designed and built. The autosampler ...

  20. Sampling of air streams and incorporation of samples in the Microtox{trademark} toxicity testing system

    SciTech Connect

    Kleinheinz, G.T.; St. John, W.P.

    1997-10-01

    A study was conducted to develop a rapid and reliable method for the collection and incorporation of biofiltration air samples containing volatile organic compounds (VOCs) into the Microtox toxicity testing system. To date, no method exists for this type of assay. A constant stream of VOCs was generated by air stripping compounds from a complex mixture of petroleum hydrocarbons (PHCs). Samples were collected on coconut charcoal ORBO tubes and the VOCs extracted with methylene chloride. The compounds extracted were then solvent exchanged into dimethyl sulfoxide (DMSO) under gaseous nitrogen. The resulting DMSO extract was directly incorporated into the Microtox toxicity testing system. In order to determine the efficiency of the solvent exchange, the VOCs in the DMSO extract were then extracted into hexane and subsequently analyzed using gas chromatography (GC) with a flame ionization detector (FID). It was determined that all but the most volatile VOCs could be effectively transferred from the ORBO tubes to DMSO for Microtox testing. Potential trace amounts of residual methylene chloride in the DMSO extracts showed no adverse effects in the Microtox system when compared to control samples.

  1. Passive Samplers for Investigations of Air Quality: Method Description, Implementation, and Comparison to Alternative Sampling Methods

    EPA Science Inventory

    This Paper covers the basics of passive sampler design, compares passive samplers to conventional methods of air sampling, and discusses considerations when implementing a passive sampling program. The Paper also discusses field sampling and sample analysis considerations to ensu...

  2. Monitoring air quality in mountains: Designing an effective network

    USGS Publications Warehouse

    Peterson, D.L.

    2000-01-01

    A quantitatively robust yet parsimonious air-quality monitoring network in mountainous regions requires special attention to relevant spatial and temporal scales of measurement and inference. The design of monitoring networks should focus on the objectives required by public agencies, namely: 1) determine if some threshold has been exceeded (e.g., for regulatory purposes), and 2) identify spatial patterns and temporal trends (e.g., to protect natural resources). A short-term, multi-scale assessment to quantify spatial variability in air quality is a valuable asset in designing a network, in conjunction with an evaluation of existing data and simulation-model output. A recent assessment in Washington state (USA) quantified spatial variability in tropospheric ozone distribution ranging from a single watershed to the western third of the state. Spatial and temporal coherence in ozone exposure modified by predictable elevational relationships ( 1.3 ppbv ozone per 100 m elevation gain) extends from urban areas to the crest of the Cascade Range. This suggests that a sparse network of permanent analyzers is sufficient at all spatial scales, with the option of periodic intensive measurements to validate network design. It is imperative that agencies cooperate in the design of monitoring networks in mountainous regions to optimize data collection and financial efficiencies.

  3. Kaolin Quality Prediction from Samples: A Bayesian Network Approach

    SciTech Connect

    Rivas, T.; Taboada, J.; Ordonez, C.; Matias, J. M.

    2009-08-13

    We describe the results of an expert system applied to the evaluation of samples of kaolin for industrial use in paper or ceramic manufacture. Different machine learning techniques - classification trees, support vector machines and Bayesian networks - were applied with the aim of evaluating and comparing their interpretability and prediction capacities. The predictive capacity of these models for the samples analyzed was highly satisfactory, both for ceramic quality and paper quality. However, Bayesian networks generally proved to be the most useful technique for our study, as this approach combines good predictive capacity with excellent interpretability of the kaolin quality structure, as it graphically represents relationships between variables and facilitates what-if analyses.

  4. Uniform Sampling for Directed P2P Networks

    NASA Astrophysics Data System (ADS)

    Hall, Cyrus; Carzaniga, Antonio

    Selecting a random peer with uniform probability across a peer-to-peer (P2P) network is a fundamental function for unstructured search, data replication, and monitoring algorithms. Such uniform sampling is supported by several techniques. However, current techniques suffer from sample bias and limited applicability. In this paper, we present a sampling algorithm that achieves a desired uniformity while making essentially no assumptions about the underlying P2P network. This algorithm, called doubly stochastic converge (DSC), iteratively adjusts the probabilities of crossing each link in the network during a random walk, such that the resulting transition matrix is doubly stochastic. DSC is fully decentralized and is designed to work on both directed and undirected topologies, making it suitable for virtually any P2P network. Our simulations show that DSC converges quickly on a wide variety of topologies, and that the random walks needed for sampling are short for most topologies. In simulation studies with FreePastry, we show that DSC is resilient to high levels of churn, while incurring a minimal sample bias.

  5. An Optimization of the Maintenance Assets Distribution Network in the Argentine Air Force

    DTIC Science & Technology

    2015-03-26

    AN OPTIMIZATION OF THE MAINTENANCE ASSETS DISTRIBUTION NETWORK IN THE ARGENTINE AIR FORCE...copyright protection in the United States. AFIT-ENS-MS-15-M-152 AN OPTIMIZATION OF THE MAINTENANCE ASSETS DISTRIBUTION NETWORK IN THE ARGENTINE AIR...PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT-ENS-MS-15-M-152 AN OPTIMIZATION OF THE MAINTENANCE ASSETS DISTRIBUTION NETWORK IN THE ARGENTINE AIR

  6. Carter Carburetor Weekly Air Monitoring & Sampling Report - November 2, 2015 – November 8, 2015

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  7. Carter Carburetor Weekly Air Monitoring & Sampling Report - November 16, 2015 – November 22, 2015

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  8. Carter Carburetor Weekly Air Monitoring & Sampling Report - October 12, 2015 – October 18, 2015

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  9. Carter Carburetor Weekly Air Monitoring & Sampling Report - March 7, 2013 - March 13, 2016

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  10. Carter Carburetor Weekly Air Monitoring & Sampling Report - November 30, 2015 – December 6, 2015

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  11. Carter Carburetor Weekly Air Monitoring & Sampling Report - November 9, 2015 – November 15, 2015

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  12. Carter Carburetor Weekly Air Monitoring & Sampling Report - February 1, 2016 – February 7, 2016

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  13. Carter Carburetor Weekly Air Monitoring & Sampling Report - October 26, 2015 – November 1, 2015

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  14. Carter Carburetor Weekly Air Monitoring & Sampling Report - October 5, 2015 – October 11, 2015

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  15. Carter Carburetor Weekly Air Monitoring & Sampling Report - September 28, 2015 – October 4, 2015

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  16. Carter Carburetor Weekly Air Monitoring & Sampling Report - February 15, 2016 – February 21, 2016

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  17. Carter Carburetor Weekly Air Monitoring & Sampling Report - October 19, 2015 – October 25, 2015

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  18. Carter Carburetor Weekly Air Monitoring & Sampling Report - November 23, 2015 – November 29, 2015

    EPA Pesticide Factsheets

    Carter Carburetor Daily Weather Conditions, Dairly Work Activities, Daily Air Monitoring and Samplying Results, Air Monitoring/Samplying Results –Station 2 Linc 126, Air Monitoring/Sampling Results- Sation 3 Linc 123, Air Monitoring/Samplying Results-Stati

  19. An Architectural Concept for Intrusion Tolerance in Air Traffic Networks

    NASA Technical Reports Server (NTRS)

    Maddalon, Jeffrey M.; Miner, Paul S.

    2003-01-01

    The goal of an intrusion tolerant network is to continue to provide predictable and reliable communication in the presence of a limited num ber of compromised network components. The behavior of a compromised network component ranges from a node that no longer responds to a nod e that is under the control of a malicious entity that is actively tr ying to cause other nodes to fail. Most current data communication ne tworks do not include support for tolerating unconstrained misbehavio r of components in the network. However, the fault tolerance communit y has developed protocols that provide both predictable and reliable communication in the presence of the worst possible behavior of a limited number of nodes in the system. One may view a malicious entity in a communication network as a node that has failed and is behaving in an arbitrary manner. NASA/Langley Research Center has developed one such fault-tolerant computing platform called SPIDER (Scalable Proces sor-Independent Design for Electromagnetic Resilience). The protocols and interconnection mechanisms of SPIDER may be adapted to large-sca le, distributed communication networks such as would be required for future Air Traffic Management systems. The predictability and reliabi lity guarantees provided by the SPIDER protocols have been formally v erified. This analysis can be readily adapted to similar network stru ctures.

  20. Collection and analysis of NASA clean room air samples

    NASA Technical Reports Server (NTRS)

    Sheldon, L. S.; Keever, J.

    1985-01-01

    The environment of the HALOE assembly clean room at NASA Langley Research Center is analyzed to determine the background levels of airborne organic compounds. Sampling is accomplished by pumping the clean room air through absorbing cartridges. For volatile organics, cartridges are thermally desorbed and then analyzed by gas chromatography and mass spectrometry, compounds are identified by searching the EPA/NIH data base using an interactive operator INCOS computer search algorithm. For semivolatile organics, cartridges are solvent entracted and concentrated extracts are analyzed by gas chromatography-electron capture detection, compound identification is made by matching gas chromatogram retention times with known standards. The detection limits for the semivolatile organics are; 0.89 ng cu m for dioctylphlhalate (DOP) and 1.6 ng cu m for polychlorinated biphenyls (PCB). The detection limit for volatile organics ranges from 1 to 50 parts per trillion. Only trace quantities of organics are detected, the DOP levels do not exceed 2.5 ng cu m and the PCB levels do not exceed 454 ng cu m.

  1. Stochastic Network Interdiction for Optimizing Defensive Counter Air Operations Planning

    DTIC Science & Technology

    2011-12-01

    the interdictor reveals his defensive strategy . Washburn and Wood [8] view the network interdiction problem as a simultaneous, two-person, zero-sum... the distance to the nearest refueling point . For example, the cost for an area ( , )i j AI∈ is one if an aircraft formation can stay on combat air...combination of area defense and point defense allows the defender to deploy more efficient tactics and protect more friendly assets with fewer resources

  2. ASSESSING THE COMPARABILITY OF AMMONIUM, NITRATE AND SULFATE CONCENTRATIONS MEASURED BY THREE AIR QUALITY MONITORING NETWORKS

    EPA Science Inventory

    Airborne fine particulate matter across the United States is monitored by different networks, the three prevalent ones presently being the Clean Air Status and Trend Network (CASTNet), the Interagency Monitoring of PROtected Visual Environment Network (IMPROVE) and the Speciati...

  3. Breakthrough of 1,3-dichloropropene and chloropicrin from 600 mg XAD-4 air sampling tubes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurately measuring air concentrations of agricultural fumigants is important for the regulation of air quality. Understanding the conditions under which sorbent tubes can effectively retain such fumigants during sampling is critical in mitigating chemical breakthrough from the tubes and facilitati...

  4. Sample EP Flow Analysis of Severely Damaged Networks

    SciTech Connect

    Werley, Kenneth Alan; McCown, Andrew William

    2016-10-12

    These are slides for a presentation at the working group meeting of the WESC SREMP Software Product Integration Team on sample EP flow analysis of severely damaged networks. The following topics are covered: ERCOT EP Transmission Model; Zoomed in to Houston and Overlaying StreetAtlas; EMPACT Solve/Dispatch/Shedding Options; QACS BaseCase Power Flow Solution; 3 Substation Contingency; Gen. & Load/100 Optimal Dispatch; Dispatch Results; Shed Load for Low V; Network Damage Summary; Estimated Service Areas (Potential); Estimated Outage Areas (potential).

  5. Network Visualization of Conformational Sampling during Molecular Dynamics Simulation

    PubMed Central

    Ahlstrom, Logan S.; Baker, Joseph Lee; Ehrlich, Kent; Campbell, Zachary T.; Patel, Sunita; Vorontsov, Ivan I.; Tama, Florence; Miyashita, Osamu

    2013-01-01

    Effective data reduction methods are necessary for uncovering the inherent conformational relationships present in large molecular dynamics (MD) trajectories. Clustering algorithms provide a means to interpret the conformational sampling of molecules during simulation by grouping trajectory snapshots into a few subgroups, or clusters, but the relationships between the individual clusters may not be readily understood. Here we show that network analysis can be used to visualize the dominant conformational states explored during simulation as well as the connectivity between them, providing a more coherent description of conformational space than traditional clustering techniques alone. We compare the results of network visualization against 11 clustering algorithms and principal component conformer plots. Several MD simulations of proteins undergoing different conformational changes demonstrate the effectiveness of networks in reaching functional conclusions. PMID:24211466

  6. Graph animals, subgraph sampling, and motif search in large networks.

    PubMed

    Baskerville, Kim; Grassberger, Peter; Paczuski, Maya

    2007-09-01

    We generalize a sampling algorithm for lattice animals (connected clusters on a regular lattice) to a Monte Carlo algorithm for "graph animals," i.e., connected subgraphs in arbitrary networks. As with the algorithm in [N. Kashtan et al., Bioinformatics 20, 1746 (2004)], it provides a weighted sample, but the computation of the weights is much faster (linear in the size of subgraphs, instead of superexponential). This allows subgraphs with up to ten or more nodes to be sampled with very high statistics, from arbitrarily large networks. Using this together with a heuristic algorithm for rapidly classifying isomorphic graphs, we present results for two protein interaction networks obtained using the tandem affinity purification (TAP) method: one of Escherichia coli with 230 nodes and 695 links, and one for yeast (Saccharomyces cerevisiae) with roughly ten times more nodes and links. We find in both cases that most connected subgraphs are strong motifs (Z scores >10) or antimotifs (Z scores <-10) when the null model is the ensemble of networks with fixed degree sequence. Strong differences appear between the two networks, with dominant motifs in E. coli being (nearly) bipartite graphs and having many pairs of nodes that connect to the same neighbors, while dominant motifs in yeast tend towards completeness or contain large cliques. We also explore a number of methods that do not rely on measurements of Z scores or comparisons with null models. For instance, we discuss the influence of specific complexes like the 26S proteasome in yeast, where a small number of complexes dominate the k cores with large k and have a decisive effect on the strongest motifs with 6-8 nodes. We also present Zipf plots of counts versus rank. They show broad distributions that are not power laws, in contrast to the case when disconnected subgraphs are included.

  7. Graph animals, subgraph sampling, and motif search in large networks

    NASA Astrophysics Data System (ADS)

    Baskerville, Kim; Grassberger, Peter; Paczuski, Maya

    2007-09-01

    We generalize a sampling algorithm for lattice animals (connected clusters on a regular lattice) to a Monte Carlo algorithm for “graph animals,” i.e., connected subgraphs in arbitrary networks. As with the algorithm in [N. Kashtan , Bioinformatics 20, 1746 (2004)], it provides a weighted sample, but the computation of the weights is much faster (linear in the size of subgraphs, instead of superexponential). This allows subgraphs with up to ten or more nodes to be sampled with very high statistics, from arbitrarily large networks. Using this together with a heuristic algorithm for rapidly classifying isomorphic graphs, we present results for two protein interaction networks obtained using the tandem affinity purification (TAP) method: one of Escherichia coli with 230 nodes and 695 links, and one for yeast (Saccharomyces cerevisiae) with roughly ten times more nodes and links. We find in both cases that most connected subgraphs are strong motifs ( Z scores >10 ) or antimotifs ( Z scores <-10 ) when the null model is the ensemble of networks with fixed degree sequence. Strong differences appear between the two networks, with dominant motifs in E. coli being (nearly) bipartite graphs and having many pairs of nodes that connect to the same neighbors, while dominant motifs in yeast tend towards completeness or contain large cliques. We also explore a number of methods that do not rely on measurements of Z scores or comparisons with null models. For instance, we discuss the influence of specific complexes like the 26S proteasome in yeast, where a small number of complexes dominate the k cores with large k and have a decisive effect on the strongest motifs with 6-8 nodes. We also present Zipf plots of counts versus rank. They show broad distributions that are not power laws, in contrast to the case when disconnected subgraphs are included.

  8. Digital Curation of Marine Physical Samples at Ocean Networks Canada

    NASA Astrophysics Data System (ADS)

    Jenkyns, R.; Tomlin, M. C.; Timmerman, R.

    2015-12-01

    Ocean Networks Canada (ONC) has collected hundreds of geological, biological and fluid samples from the water column and seafloor during its maintenance expeditions. These samples have been collected by Remotely Operated Vehicles (ROVs), divers, networked and autonomously deployed instruments, and rosettes. Subsequent measurements are used for scientific experiments, calibration of in-situ and remote sensors, monitoring of Marine Protected Areas, and environment characterization. Tracking the life cycles of these samples from collection to dissemination of results with all the pertinent documents (e.g., protocols, imagery, reports), metadata (e.g., location, identifiers, purpose, method) and data (e.g., measurements, taxonomic classification) is a challenge. The initial collection of samples is normally documented in SeaScribe (an ROV dive logging tool within ONC's Oceans 2.0 software) for which ONC has defined semantics and syntax. Next, samples are often sent to individual scientists and institutions (e.g., Royal BC Museum) for processing and storage, making acquisition of results and life cycle metadata difficult. Finally, this information needs to be retrieved and collated such that multiple user scenarios can be addressed. ONC aims to improve and extend its digital infrastructure for physical samples to support this complex array of samples, workflows and applications. However, in order to promote effective data discovery and exchange, interoperability and community standards must be an integral part of the design. Thus, integrating recommendations and outcomes of initiatives like the EarthCube iSamples working groups are essential. Use cases, existing tools, schemas and identifiers are reviewed, while remaining gaps and challenges are identified. The current status, selected approaches and possible future directions to enhance ONC's digital infrastructure for each sample type are presented.

  9. Review of Various Air Sampling Methods for Solvent Vapors.

    DTIC Science & Technology

    Vapors of trichloroethylene, toluene, methyl ethyl ketone, and butyl cellosolve in air were collected using Scotchpac and Tedlar bags, glass ...prescription bottles , and charcoal adsorption tubes. Efficiencies of collection are reported. (Author)

  10. Review of Various Air Sampling Methods for Solvent Vapors.

    ERIC Educational Resources Information Center

    Maykoski, R. T.

    Vapors of trichloroethylene, toluene, methyl ethyl ketone, and butyl cellosolve in air were collected using Scotchpac and Tedlar bags, glass prescription bottles, and charcoal adsorption tubes. Efficiencies of collection are reported. (Author/RH)

  11. Training augmentation device for the Air Force satellite Control Network

    NASA Technical Reports Server (NTRS)

    Shoates, Keith B.

    1993-01-01

    From the 1960's and into the early 1980's satellite operations and control were conducted by Air Force Systems Command (AFSC), now Air Force Materiel Command (AFMC), out of the Satellite Control Facility at Onizuka AFB, CA. AFSC was responsible for acquiring satellite command and control systems and conducting routine satellite operations. The daily operations, consisting of satellite health and status contacts and station keeping activities, were performed for AFSC by a Mission Control Team (MCT) staffed by civilian contractors who were responsible for providing their own technically 'qualified' personnel as satellite operators. An MCT consists of five positions: mission planner, ground controller, planner analyst, orbit analyst, and ranger controller. Most of the training consisted of On-the-Job-Training (OJT) with junior personnel apprenticed to senior personnel until they could demonstrate job proficiency. With most of the satellite operators having 15 to 25 years of experience, there was minimal risk to the mission. In the mid 1980's Air Force Space Command (AFSPACOM) assumed operational responsibility for a newly established control node at Falcon AFB (FAFB) in CO. The satellites and ground system program offices (SPO's) are organized under AFSC's Space and Missiles Systems Center (SMC) to function as a systems engineering and acquisition agency for AFSPACECOM. The collection of the satellite control nodes, ground tracking stations, computer processing equipment, and connecting communications links is referred to as the Air Force Satellite Control Network (AFSCN).

  12. Dynamic Sampling and Information Encoding in Biochemical Networks

    NASA Astrophysics Data System (ADS)

    Potter, Garrett D.; Byrd, Tommy A.; Mugler, Andrew; Sun, Bo

    2017-02-01

    Cells use biochemical networks to translate environmental information into intracellular responses. These responses can be highly dynamic, but how the information is encoded in these dynamics remains poorly understood. Here we investigate the dynamic encoding of information in the ATP-induced calcium responses of fibroblast cells, using a vectorial, or multi-time-point, measure from information theory. We find that the amount of extracted information depends on physiological constraints such as the sampling rate and memory capacity of the downstream network, and is affected differentially by intrinsic vs. extrinsic noise. By comparing to a minimal physical model, we find, surprisingly, that the information is often insensitive to the detailed structure of the underlying dynamics, and instead the decoding mechanism acts as a simple low-pass filter. These results demonstrate the mechanisms and limitations of dynamic information storage in cells.

  13. Low-cost monitoring of Campylobacter in poultry houses by air sampling and quantitative PCR.

    PubMed

    Søndergaard, M S R; Josefsen, M H; Löfström, C; Christensen, L S; Wieczorek, K; Osek, J; Hoorfar, J

    2014-02-01

    The present study describes the evaluation of a method for the quantification of Campylobacter by air sampling in poultry houses. Sampling was carried out in conventional chicken houses in Poland, in addition to a preliminary sampling in Denmark. Each measurement consisted of three air samples, two standard boot swab fecal samples, and one airborne particle count. Sampling was conducted over an 8-week period in three flocks, assessing the presence and levels of Campylobacter in boot swabs and air samples using quantitative real-time PCR. The detection limit for air sampling was approximately 100 Campylobacter cell equivalents (CCE)/m3. Airborne particle counts were used to analyze the size distribution of airborne particles (0.3 to 10 μm) in the chicken houses in relation to the level of airborne Campylobacter. No correlation was found. Using air sampling, Campylobacter was detected in the flocks right away, while boot swab samples were positive after 2 weeks. All samples collected were positive for Campylobacter from week 2 through the rest of the rearing period for both sampling techniques, although levels 1- to 2-log CCE higher were found with air sampling. At week 8, the levels were approximately 10(4) and 10(5) CCE per sample for boot swabs and air, respectively. In conclusion, using air samples combined with quantitative real-time PCR, Campylobacter contamination could be detected earlier than by boot swabs and was found to be a more convenient technique for monitoring and/or to obtain enumeration data useful for quantitative risk assessment of Campylobacter.

  14. Cluster analysis of passive air sampling data based on the relative composition of persistent organic pollutants.

    PubMed

    Liu, Xiande; Wania, Frank

    2014-03-01

    The development of passive air samplers has allowed the measurement of time-integrated concentrations of persistent organic pollutants (POPs) within spatial networks on a variety of scales. Cluster analysis of POP composition may enhance the interpretation of such spatial data. Several methodological aspects of the application of cluster analysis are discussed, including the influence of a dominant pollutant, the role of PAS duplication, and comparison of regional studies. Relying on data from six regional studies in North and South America, Africa, and Asia, we illustrate here how cluster analysis can be used to extract information and gain insights into POP sources and atmospheric transport contributions. Cluster analysis allows classification of PAS samples into those with significant local source contributions and those that represent regional fingerprints. Local emissions, atmospheric transport, and seasonal cycles are identified as being among the major factors determining the variation in POP composition at many sites. By complementing cluster analysis with meteorological data such as air mass back-trajectories, terrain, as well as geographical and socio-economic aspects, a comprehensive picture of the atmospheric contamination of a region by POPs emerges.

  15. Near-Road Air Quality Monitoring: Factors Affecting Network Design and Interpretation of Data

    EPA Science Inventory

    The growing number of health studies identifying adverse health effects for populations spending significant amounts of time near large roadways has increased the interest in monitoring air quality in this microenvironment. Designing near-road air monitoring networks or interpret...

  16. Toxicological Assessment of ISS Air Quality: Contingency Sampling - February 2013

    NASA Technical Reports Server (NTRS)

    Meyers, Valerie

    2013-01-01

    Two grab sample containers (GSCs) were collected by crew members onboard ISS in response to a vinegar-like odor in the US Lab. On February 5, the first sample was collected approximately 1 hour after the odor was noted by the crew in the forward portion of the Lab. The second sample was collected on February 22 when a similar odor was noted and localized to the end ports of the microgravity science glovebox (MSG). The crewmember removed a glove from the MSG and collected the GSC inside the glovebox volume. Both samples were returned on SpaceX-2 for ground analysis.

  17. Sampling microbial communities in the National Ecological Observatory Network

    NASA Astrophysics Data System (ADS)

    Adams, H. E.; Parnell, J.; Powell, H.

    2012-12-01

    The National Ecological Observatory Network (NEON) is a national-scale research platform to enable the community to assess impacts of climate change, land-use change, and invasive species on ecosystem structure and function at regional and continental scales. The NEON Observatory will collect data on aquatic organisms over 30 years in 36 sites across the United States, including Alaska and Puerto Rico as well as terrestrial organisms at 60 sites including Hawaii. Included in the biological measurements are microbial measurements in terrestrial and aquatic environments, including small, wadeable streams and shallow lakes. Microbial sampling in both aquatic and terrestrial habitats is being planned to coincide with biogeochemical sampling due to similarity of time scale and influence of external drivers. Aquatic sampling is geared toward species diversity and function. Terrestrial sampling aims to collect data on diversity, function, and spatial distribution dynamics. We are in the process of prioritizing data products, so that the most dynamic processes such as enzymatic activity will be measured more frequently and more intensive measures such as metagenome sequence data will be measured on a periodic basis. Here we present our initial microbial sampling strategy and invite the community to provide comment on the design and learn about microbial data products from the Observatory.

  18. Sampled-Data State Feedback Stabilization of Boolean Control Networks.

    PubMed

    Liu, Yang; Cao, Jinde; Sun, Liangjie; Lu, Jianquan

    2016-04-01

    In this letter, we investigate the sampled-data state feedback control (SDSFC) problem of Boolean control networks (BCNs). Some necessary and sufficient conditions are obtained for the global stabilization of BCNs by SDSFC. Different from conventional state feedback controls, new phenomena observed the study of SDSFC. Based on the controllability matrix, we derive some necessary and sufficient conditions under which the trajectories of BCNs can be stabilized to a fixed point by piecewise constant control (PCC). It is proved that the global stabilization of BCNs under SDSFC is equivalent to that by PCC. Moreover, algorithms are given to construct the sampled-data state feedback controllers. Numerical examples are given to illustrate the efficiency of the obtained results.

  19. Detection of the Urban Release of a Bacillus anthracis Simulant by Air Sampling

    PubMed Central

    Garza, Alexander G.; Van Cuyk, Sheila M.; Brown, Michael J.

    2014-01-01

    In 2005 and 2009, the Pentagon Force Protection Agency (PFPA) staged deliberate releases of a commercially available organic pesticide containing Bacillus amyloliquefaciens to evaluate PFPA's biothreat response protocols. In concert with, but independent of, these releases, the Department of Homeland Security sponsored experiments to evaluate the efficacy of commonly employed air and surface sampling techniques for detection of an aerosolized biological agent. High-volume air samplers were placed in the expected downwind plume, and samples were collected before, during, and after the releases. Environmental surface and personal air samples were collected in the vicinity of the high-volume air samplers hours after the plume had dispersed. The results indicate it is feasible to detect the release of a biological agent in an urban area both during and after the release of a biological agent using high-volume air and environmental sampling techniques. PMID:24697146

  20. Detection of the urban release of a bacillus anthracis simulant by air sampling.

    PubMed

    Garza, Alexander G; Van Cuyk, Sheila M; Brown, Michael J; Omberg, Kristin M

    2014-01-01

    In 2005 and 2009, the Pentagon Force Protection Agency (PFPA) staged deliberate releases of a commercially available organic pesticide containing Bacillus amyloliquefaciens to evaluate PFPA's biothreat response protocols. In concert with, but independent of, these releases, the Department of Homeland Security sponsored experiments to evaluate the efficacy of commonly employed air and surface sampling techniques for detection of an aerosolized biological agent. High-volume air samplers were placed in the expected downwind plume, and samples were collected before, during, and after the releases. Environmental surface and personal air samples were collected in the vicinity of the high-volume air samplers hours after the plume had dispersed. The results indicate it is feasible to detect the release of a biological agent in an urban area both during and after the release of a biological agent using high-volume air and environmental sampling techniques.

  1. Identifying a Probabilistic Boolean Threshold Network From Samples.

    PubMed

    Melkman, Avraham A; Cheng, Xiaoqing; Ching, Wai-Ki; Akutsu, Tatsuya

    2017-01-25

    This paper studies the problem of exactly identifying the structure of a probabilistic Boolean network (PBN) from a given set of samples, where PBNs are probabilistic extensions of Boolean networks. Cheng et al. studied the problem while focusing on PBNs consisting of pairs of AND/OR functions. This paper considers PBNs consisting of Boolean threshold functions while focusing on those threshold functions that have unit coefficients. The treatment of Boolean threshold functions, and triplets and n-tuplets of such functions, necessitates a deepening of the theoretical analyses. It is shown that wide classes of PBNs with such threshold functions can be exactly identified from samples under reasonable constraints, which include: 1) PBNs in which any number of threshold functions can be assigned provided that all have the same number of input variables and 2) PBNs consisting of pairs of threshold functions with different numbers of input variables. It is also shown that the problem of deciding the equivalence of two Boolean threshold functions is solvable in pseudopolynomial time but remains co-NP complete.

  2. Review of the Physical Science Facility Stack Air Sampling Probe Locations

    SciTech Connect

    Glissmeyer, John A.

    2007-09-30

    This letter report reviews compliance of the current design of the Physical Science Facility (PSF) stack air sampling locations with the ANSI/HPS N13.1-1999 standard. The review was based on performance criteria used for locating air sampling probes, the design documents provided and available information on systems previously tested for compliance with the criteria. Recommendations are presented for ways to bring the design into compliance with the requirements for the sampling probe placement.

  3. 3D Air Quality and the Clean Air Interstate Rule: Lagrangian Sampling of CMAQ Model Results to Aid Regional Accountability Metrics

    NASA Technical Reports Server (NTRS)

    Fairlie, T. D.; Szykman, Jim; Pierce, Robert B.; Gilliland, A. B.; Engel-Cox, Jill; Weber, Stephanie; Kittaka, Chieko; Al-Saadi, Jassim A.; Scheffe, Rich; Dimmick, Fred; Tikvart, Joe

    2008-01-01

    The Clean Air Interstate Rule (CAIR) is expected to reduce transport of air pollutants (e.g. fine sulfate particles) in nonattainment areas in the Eastern United States. CAIR highlights the need for an integrated air quality observational and modeling system to understand sulfate as it moves in multiple dimensions, both spatially and temporally. Here, we demonstrate how results from an air quality model can be combined with a 3d monitoring network to provide decision makers with a tool to help quantify the impact of CAIR reductions in SO2 emissions on regional transport contributions to sulfate concentrations at surface monitors in the Baltimore, MD area, and help improve decision making for strategic implementation plans (SIPs). We sample results from the Community Multiscale Air Quality (CMAQ) model using ensemble back trajectories computed with the NASA Langley Research Center trajectory model to provide Lagrangian time series and vertical profile information, that can be compared with NASA satellite (MODIS), EPA surface, and lidar measurements. Results are used to assess the regional transport contribution to surface SO4 measurements in the Baltimore MSA, and to characterize the dominant source regions for low, medium, and high SO4 episodes.

  4. Situation assessment for air combat based on the Bayesian networks technology

    NASA Astrophysics Data System (ADS)

    Sun, Zhaolin; Yang, Hongwen; Hu, Weidong; Yu, Wenxian

    2005-11-01

    This paper researches on the method of situation assessment for the air combat based on the Bayesian networks technology. It analyzes the events occur in the process of air combat, and presents a hybrid method of fuzzy sets and Bayesian networks to detect these events. Then, it presents a method to construct Bayesian networks using the events and then uses the networks to reason the purpose of enemy fighter pilots. Finally, it shows the method by an illustrative example.

  5. Comparison of stationary and personal air sampling with an air dispersion model for children's ambient exposure to manganese.

    PubMed

    Fulk, Florence; Haynes, Erin N; Hilbert, Timothy J; Brown, David; Petersen, Dan; Reponen, Tiina

    2016-09-01

    Manganese (Mn) is ubiquitous in the environment and essential for normal growth and development, yet excessive exposure can lead to impairments in neurological function. This study modeled ambient Mn concentrations as an alternative to stationary and personal air sampling to assess exposure for children enrolled in the Communities Actively Researching Exposure Study in Marietta, OH. Ambient air Mn concentration values were modeled using US Environmental Protection Agency's Air Dispersion Model AERMOD based on emissions from the ferromanganese refinery located in Marietta. Modeled Mn concentrations were compared with Mn concentrations from a nearby stationary air monitor. The Index of Agreement for modeled versus monitored data was 0.34 (48 h levels) and 0.79 (monthly levels). Fractional bias was 0.026 for 48 h levels and -0.019 for monthly levels. The ratio of modeled ambient air Mn to measured ambient air Mn at the annual time scale was 0.94. Modeled values were also time matched to personal air samples for 19 children. The modeled values explained a greater degree of variability in personal exposures compared with time-weighted distance from the emission source. Based on these results modeled Mn concentrations provided a suitable approach for assessing airborne Mn exposure in this cohort.

  6. Sampling network stratification by terrain classification in eroded agricultural landscapes at plot scale

    NASA Astrophysics Data System (ADS)

    Penížek, Vít; Zádorová, Tereza; Kodešová, Radka

    2015-04-01

    The description of soil properties variability is important aspect in land management and food production at plot scale. We describe novelty approach for design of sampling network on agricultural plots with high relief variability. The terrain properties were used for improved spatial prediction of soil properties including design of the sampling network. Regular sampling network, random sampling network, systematic unaligned sampling network and stratified sampling network schemes were compared to prove the advantages of relief based stratified sampling networks. The study was performed for humus horizon depth prediction on agriculture plot of 6.5 ha with dissected relief where originally homogenous soil cover was differentiated by erosion and sedimentation into mosaic of Chernozem, Regosol and colluvial soils. Moreover the comparison was done on three levels of sampling density (65, 40 and 24 sampling points). The stratification of sampling network was based on unsupervised relief classification. The performance of the soil properties prediction based on different sampling network was assesed by RMSE calculation based on predicted values versus validation dataset. According the RMSE, the stratified sampling network performed the best (7.4 cm) comparing the regular sampling network (10.8 cm), random sampling network (17.7 cm) and systematic unaligned sampling network (11.2 cm). The accuracy of the soil properties spatial prediction decreased with the decreasing number of sampling points, but the stratified network performed significantly better that other used methods. The study showed that, for soil properties spatial variability description at certain accuracy level, relief-based stratified network can contain 25 % less sampling points comparing to regular network. This leads to potential financial and person cost reduction for the soil survey. The study was supported by grant nr. 13-07516P of the Czech science foundation and by grant nr. QJ1230319 of the

  7. Summary of gamma spectrometry on local air samples from 1985--1995

    SciTech Connect

    Winn, W.G.

    1997-04-02

    This report summarizes the 1985--1995 results of low-level HPGe gamma spectrometry analysis of high-volume air samples collected at the Aiken Airport, which is about 25 miles north of SRS. The author began analyzing these samples with new calibrations using the newly developed GRABGAM code in 1985. The air sample collections were terminated in 1995, as the facilities at the Aiken Airport were no longer available. Air sample measurements prior to 1985 were conducted with a different analysis system (and by others prior to 1984), and the data were not readily available. The report serves to closeout this phase of local NTS air sample studies, while documenting the capabilities and accomplishments. Hopefully, the information will guide other applications for this technology, both locally and elsewhere.

  8. Minimum detectable activity concentration in direct alpha spectrometry from outdoor air samples: continuous monitoring versus separate sampling and counting.

    PubMed

    Pöllänen, R; Siiskonen, T

    2006-02-01

    Rapid method for identifying the presence of alpha particle emitting radionuclides in outdoor air is of paramount importance should a nuclear or radiological incident occur. Minimum detectable activity concentrations of U, U, Pu, and Pu in outdoor air are calculated for two direct alpha spectrometry methods: continuous air monitoring is compared with separate sampling and subsequent alpha particle counting in a vacuum chamber. The radon progeny activity concentration typical for outdoor air and the effects for the alpha particle spectra caused by the properties of the filter and the aerosol particles are taken into account using measurements and Monte Carlo simulations. Continuous air monitoring is a faster method for identifying the presence of (trans)uranium elements when their activity concentration is considerably higher than the typical detection limit. Separate sampling and counting in a vacuum chamber is a more sensitive method when concentrations are close to the detection limit and when the duration of the sampling-counting cycle is greater than approximately 2 h. The method may serve as a tool for rapid field measurements.

  9. A method to optimize sampling locations for measuring indoor air distributions

    NASA Astrophysics Data System (ADS)

    Huang, Yan; Shen, Xiong; Li, Jianmin; Li, Bingye; Duan, Ran; Lin, Chao-Hsin; Liu, Junjie; Chen, Qingyan

    2015-02-01

    Indoor air distributions, such as the distributions of air temperature, air velocity, and contaminant concentrations, are very important to occupants' health and comfort in enclosed spaces. When point data is collected for interpolation to form field distributions, the sampling locations (the locations of the point sensors) have a significant effect on time invested, labor costs and measuring accuracy on field interpolation. This investigation compared two different sampling methods: the grid method and the gradient-based method, for determining sampling locations. The two methods were applied to obtain point air parameter data in an office room and in a section of an economy-class aircraft cabin. The point data obtained was then interpolated to form field distributions by the ordinary Kriging method. Our error analysis shows that the gradient-based sampling method has 32.6% smaller error of interpolation than the grid sampling method. We acquired the function between the interpolation errors and the sampling size (the number of sampling points). According to the function, the sampling size has an optimal value and the maximum sampling size can be determined by the sensor and system errors. This study recommends the gradient-based sampling method for measuring indoor air distributions.

  10. Regional climate network analysis from irregularly sampled satellite data

    NASA Astrophysics Data System (ADS)

    Wiedermann, Marc; Sykioti, Olga; Papadimitriou, Constantinos; Balasis, George; Kurths, Jürgen; Donner, Reik V.

    2016-04-01

    With the increasing availability of remote sensing data Earth System Analysis has taken a great step forward. This type of data, however, also harbors a variety of conceptual complications. First, depending on whether the satellite is orbiting on an ascending or descending path systematic biases are induced into the data, and both measurements cannot be evaluated simultaneously without an appropriate preprocessing. Second, remote sensing data are usually not produced with equidistant temporal sampling, but might contain huge gaps and irregular time steps. Third, the time period covered by the data is often too short to perform an appropriate seasonal detrending. Here, we propose a general framework to create homogeneous anomalized time series for a (multivariate) satellite data set by combining time series from ascending and descending satellite paths or even different missions using principal component and singular spectrum analysis. We then exemplarily apply our method to sea surface temperature data obtained from the SMOS satellite mission to study small-scale regional correlative patterns covering different parts of the Aegean Sea. To address the issue of irregular temporal sampling we utilize a kernel weighted version of the linear cross-correlation function to compute lagged correlations between all pairs of grid points in the data set. By binarizing the thus obtained matrices, we obtain a network representation of the system's similarity structure. Ultimately, we use tools from complex network theory to study regional interdependencies in the study area for different time lags of up to forty days. We find that the obtained networks represent well the observed average wind directions and speeds and display interaction structures between small regions in the Aegean Sea, which are in good agreement with earlier observations. In a second step, we extend the study area to the whole Mediterranean and Black Sea and investigate lagged interactions between these two

  11. High Volume Air Sampling for Viral Aerosols: A Comparative Approach

    DTIC Science & Technology

    2010-03-01

    low, with the cotton swabbing only recovering 27.7 percent of the BA on the surface (Rose, Jensen, Peterson, Banerjee, & Arduino , 2004). A follow-on...BA were present on the surface (Hodges, Rose, Peterson, Noble-Wang, & Arduino , 2006). These lower sensitivities at low concentrations could be a...monitored during each sample collection period. Ambient pressure data was obtained hourly for Edmonton, AB from the Canadian Weather Service

  12. A STRINGENT COMPARISON OF SAMPLING AND ANALYSIS METHODS FOR VOCS IN AMBIENT AIR

    EPA Science Inventory

    A carefully designed study was conducted during the summer of 1998 to simultaneously collect samples of ambient air by canisters and compare the analysis results to direct sorbent preconcentration results taken at the time of sample collection. A total of 32 1-h sample sets we...

  13. Salmonella recovery following air chilling for matched neck-skin and whole carcass sampling methodologies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The prevalence and serogroups of Salmonella recovered following air chilling were determined for both enriched neck skin and matching enriched whole carcass samples. Commercially processed and eviscerated carcasses were air chilled to 4C before removing the neck skin (8.3 g) and stomaching in 83 mL...

  14. Monte Carlo simulation of air sampling methods for the measurement of radon decay products.

    PubMed

    Sima, Octavian; Luca, Aurelian; Sahagia, Maria

    2017-02-21

    A stochastic model of the processes involved in the measurement of the activity of the (222)Rn decay products was developed. The distributions of the relevant factors, including air sampling and radionuclide collection, are propagated using Monte Carlo simulation to the final distribution of the measurement results. The uncertainties of the (222)Rn decay products concentrations in the air are realistically evaluated.

  15. Sampling and Analyzing Air Pollution: An Apparatus Suitable for Use in Schools.

    ERIC Educational Resources Information Center

    Rockwell, Dean M.; Hansen, Tony

    1994-01-01

    Describes two variations of an air sampler and analyzer that are inexpensive to construct, easy to operate, and designed to be used in an educational program. Variations use vacuum cleaners and aquarium pumps, and white facial tissues serve as filters. Samples of air pollution obtained by this method may be used from early grade school to advanced…

  16. Analysis of (7)Be behaviour in the air by using a multilayer perceptron neural network.

    PubMed

    Samolov, A; Dragović, S; Daković, M; Bačić, G

    2014-11-01

    A multilayer perceptron artificial neural network (ANN) model for the prediction of the (7)Be behaviour in the air as the function of meteorological parameters was developed. The model was optimized and tested using (7)Be activity concentrations obtained by standard gamma-ray spectrometric analysis of air samples collected in Belgrade (Serbia) during 2009-2011 and meteorological data for the same period. Good correlation (r = 0.91) between experimental values of (7)Be activity concentrations and those predicted by ANN was obtained. The good performance of the model in prediction of (7)Be activity concentrations could provide basis for construction of models which would forecast behaviour of other airborne radionuclides.

  17. Overview of the new National Near-Road Air Quality Monitoring Network

    EPA Science Inventory

    In 2010, EPA promulgated new National Ambient Air Quality Standards (NAAQS) for nitrogen dioxide (NO2). As part of this new NAAQS, EPA required the establishment of a national near-road air quality monitoring network. This network will consist of one NO2 near-road monitoring st...

  18. NEW APPLICATION OF PASSIVE SAMPLING DEVICES FOR ASSESSMENT OF RESPIRATORY EXPOSURE TO PESTICIDES IN INDOOR AIR

    EPA Science Inventory

    The United States Environmental Protection Agency (EPA) has long maintained an interest in potential applications of passive sampling devices (PSDs) for estimating the concentrations of various pollutants in air. Typically PSDs were designed for the workplace monitoring of vola...

  19. TECHNOLOGY EVALUATION REPORT CEREX ENVIRONMENTAL SERVICES UV HOUND POINT SAMPLE AIR MONITOR

    EPA Science Inventory

    The USEPA's National Homeland Security Research Center (NHSRC) Technology Testing and Evaluation Program (TTEP) is carrying out performance tests on homeland security technologies. Under TTEP, Battelle evaluated the performance of the Cerex UV Hound point sample air monitor in de...

  20. A method for reducing and evaluating blanks in Tenax air sampling cartridges

    NASA Astrophysics Data System (ADS)

    Hubbard, Sarah A.; Russwurm, George M.; Walburn, Stephen G.

    Clean sorbent cartridges are essential in ambient air sampling to avoid false analytical results. This paper describes a procedure for the construction and cleaning of a Tenax cartridge. A definition is formulated to describe a clean cartridge quantitatively.

  1. Mixed species radioiodine air sampling readout and dose assessment system

    DOEpatents

    Distenfeld, Carl H.; Klemish, Jr., Joseph R.

    1978-01-01

    This invention provides a simple, reliable, inexpensive and portable means and method for determining the thyroid dose rate of mixed airborne species of solid and gaseous radioiodine without requiring highly skilled personnel, such as health physicists or electronics technicians. To this end, this invention provides a means and method for sampling a gas from a source of a mixed species of solid and gaseous radioiodine for collection of the mixed species and readout and assessment of the emissions therefrom by cylindrically, concentrically and annularly molding the respective species around a cylindrical passage for receiving a conventional probe-type Geiger-Mueller radiation detector.

  2. Development and Application of a Next Generation Air Sensor Network for the Hong Kong Marathon 2015 Air Quality Monitoring

    PubMed Central

    Sun, Li; Wong, Ka Chun; Wei, Peng; Ye, Sheng; Huang, Hao; Yang, Fenhuan; Westerdahl, Dane; Louie, Peter K.K.; Luk, Connie W.Y.; Ning, Zhi

    2016-01-01

    This study presents the development and evaluation of a next generation air monitoring system with both laboratory and field tests. A multi-parameter algorithm was used to correct for the impact of environmental conditions on the electrochemical sensors for carbon monoxide (CO) and nitrogen dioxide (NO2) pollutants. The field evaluation in an urban roadside environment in comparison to designated monitors showed good agreement with measurement error within 5% of the pollutant concentrations. Multiple sets of the developed system were then deployed in the Hong Kong Marathon 2015 forming a sensor-based network along the marathon route. Real-time air pollution concentration data were wirelessly transmitted and the Air Quality Health Index (AQHI) for the Green Marathon was calculated, which were broadcast to the public on an hourly basis. The route-specific sensor network showed somewhat different pollutant patterns than routine air monitoring, indicating the immediate impact of traffic control during the marathon on the roadside air quality. The study is one of the first applications of a next generation sensor network in international sport events, and it demonstrated the usefulness of the emerging sensor-based air monitoring technology in rapid network deployment to supplement existing air monitoring. PMID:26861336

  3. Development and Application of a Next Generation Air Sensor Network for the Hong Kong Marathon 2015 Air Quality Monitoring.

    PubMed

    Sun, Li; Wong, Ka Chun; Wei, Peng; Ye, Sheng; Huang, Hao; Yang, Fenhuan; Westerdahl, Dane; Louie, Peter K K; Luk, Connie W Y; Ning, Zhi

    2016-02-05

    This study presents the development and evaluation of a next generation air monitoring system with both laboratory and field tests. A multi-parameter algorithm was used to correct for the impact of environmental conditions on the electrochemical sensors for carbon monoxide (CO) and nitrogen dioxide (NO2) pollutants. The field evaluation in an urban roadside environment in comparison to designated monitors showed good agreement with measurement error within 5% of the pollutant concentrations. Multiple sets of the developed system were then deployed in the Hong Kong Marathon 2015 forming a sensor-based network along the marathon route. Real-time air pollution concentration data were wirelessly transmitted and the Air Quality Health Index (AQHI) for the Green Marathon was calculated, which were broadcast to the public on an hourly basis. The route-specific sensor network showed somewhat different pollutant patterns than routine air monitoring, indicating the immediate impact of traffic control during the marathon on the roadside air quality. The study is one of the first applications of a next generation sensor network in international sport events, and it demonstrated the usefulness of the emerging sensor-based air monitoring technology in rapid network deployment to supplement existing air monitoring.

  4. Automated syringe sampler. [remote sampling of air and water

    NASA Technical Reports Server (NTRS)

    Purgold, G. C. (Inventor)

    1981-01-01

    A number of sampling services are disposed in a rack which slides into a housing. In response to a signal from an antenna, the circutry elements are activated which provide power individually, collectively, or selectively to a servomechanism thereby moving an actuator arm and the attached jawed bracket supporting an evaculated tube towards a stationary needle. One open end of the needle extends through the side wall of a conduit to the interior and the other open end is maintained within the protective sleeve, supported by a bifurcated bracket. A septum in punctured by the end of the needle within the sleeve and a sample of the fluid medium in the conduit flows through the needle and is transferred to a tube. The signal to the servo is then reversed and the actuator arm moves the tube back to its original position permitting the septum to expand and seal the hole made by the needle. The jawed bracket is attached by pivot to the actuator to facilitate tube replacement.

  5. The NYC native air sampling pilot project: using HVAC filter data for urban biological incident characterization.

    PubMed

    Ackelsberg, Joel; Leykam, Frederic M; Hazi, Yair; Madsen, Larry C; West, Todd H; Faltesek, Anthony; Henderson, Gavin D; Henderson, Christopher L; Leighton, Terrance

    2011-09-01

    Native air sampling (NAS) is distinguished from dedicated air sampling (DAS) devices (eg, BioWatch) that are deployed to detect aerosol disseminations of biological threat agents. NAS uses filter samples from heating, ventilation, and air conditioning (HVAC) systems in commercial properties for environmental sampling after DAS detection of biological threat agent incidents. It represents an untapped, scientifically sound, efficient, widely distributed, and comparably inexpensive resource for postevent environmental sampling. Calculations predict that postevent NAS would be more efficient than environmental surface sampling by orders of magnitude. HVAC filter samples could be collected from pre-identified surrounding NAS facilities to corroborate the DAS alarm and delineate the path taken by the bioaerosol plume. The New York City (NYC) Native Air Sampling Pilot Project explored whether native air sampling would be acceptable to private sector stakeholders and could be implemented successfully in NYC. Building trade associations facilitated outreach to and discussions with property owners and managers, who expedited contact with building managers of candidate NAS properties that they managed or owned. Nominal NAS building requirements were determined; procedures to identify and evaluate candidate NAS facilities were developed; data collection tools and other resources were designed and used to expedite candidate NAS building selection and evaluation in Manhattan; and exemplar environmental sampling playbooks for emergency responders were completed. In this sample, modern buildings with single or few corporate tenants were the best NAS candidate facilities. The Pilot Project successfully demonstrated that in one urban setting a native air sampling strategy could be implemented with effective public-private collaboration.

  6. Comparison of stationary and personal air sampling with an air dispersion model for children’s ambient exposure to manganese

    EPA Science Inventory

    Manganese (Mn) is ubiquitous in the environment and essential for normal growth and development, yet excessive exposure can lead to impairments in neurological function. This study modeled ambient Mn concentrations as an alternative to stationary and personal air sampling to asse...

  7. Sampling dynamic networks with application to investigation of HIV epidemic drivers.

    PubMed

    Goyal, Ravi; De Gruttola, Victor

    2015-09-01

    We propose a method for randomly sampling dynamic networks that permits isolation of the impact of different network features on processes that propagate on networks. The new methods permit uniform sampling of dynamic networks in ways that ensure that they are consistent with both a given cumulative network and with specified values for constraints on the dynamic network properties. Development of such methods is challenging because modifying one network property will generally tend to modify others as well. Methods to sample constrained dynamic networks are particularly useful in the investigation of network-based interventions that target and modify specific dynamic network properties, especially in settings where the whole network is unobservable and therefore many network properties are unmeasurable. We illustrate this method by investigating the incremental impact of changes in networks properties that are relevant for the spread of infectious diseases, such as concurrency in sexual relationships. Development of the method is motivated by the challenges that arise in investigating the role of HIV epidemic drivers due to the often limited information available about contact networks. The proposed methods for randomly sampling dynamic networks facilitate investigation of the type of network data that can best contribute to an understanding of the HIV epidemic dynamics as well as of the limitations of conclusions drawn in the absence of such information. Hence, the methods are intended to aid in the design and interpretation of studies of network-based interventions.

  8. Sampling Dynamic Networks with Application to Investigation of HIV Epidemic Drivers

    PubMed Central

    Goyal, Ravi; De Gruttola, Victor

    2015-01-01

    We propose a method for randomly sampling dynamic networks that permits isolation of the impact of different network features on processes that propagate on networks. The new methods permit uniform sampling of dynamic networks in ways that ensure that they are consistent with both a given cumulative network and with specified values for constraints on the dynamic network properties. Development of such methods is challenging because modifying one network property will generally tend to modify others as well. Methods to sample constrained dynamic networks are particularly useful in the investigation of network-based interventions that target and modify specific dynamic network properties, especially in settings where the whole network is unobservable and therefore many network properties are unmeasurable. We illustrate this method by investigating the incremental impact of changes in networks properties that are relevant for the spread of infectious diseases, such as concurrency in sexual relationships. Development of the method is motivated by the challenges that arise in investigating the role of HIV epidemic drivers due to the often limited information available about contact networks. The proposed methods for randomly sampling dynamic networks facilitate investigation of the type of network data that can best contribute to an understanding of the HIV epidemic dynamics as well as of the limitations of conclusions drawn in the absence of such information. Hence, the methods are intended to aid in the design and interpretation of studies of network-based interventions. PMID:26200019

  9. Formaldehyde quantitation in air samples by thiazolidine derivatization: Factors affecting analysis

    SciTech Connect

    Yasuhara, A.; Shibamoto, T. )

    1989-11-01

    A new method for the determination of trace levels of formaldehyde in air was developed and validated. The method is based on the reaction of formaldehyde with cysteamine to form thiazolidine. Air samples containing trace levels of formaldehyde were prepared from paraformaldehyde. The percent yield of formaldehyde from paraformaldehyde was 85.1 +/- 1.14%. Air samples were bubbled into an aqueous cysteamine trap. Thiazolidine formed from formaldehyde and cysteamine in the trap was determined by gas chromatography with a fused silica capillary column and a nitrogen-phosphorus detector (NPD). The lowest detection level for thiazolidine was 17.2 pg, equivalent to 5.80 pg formaldehyde. The recovery efficiency of trace gas phase formaldehyde in air was greater than 90%. Formaldehyde levels in ambient laboratory air were 48.9-56.2 ppb (v/v).

  10. Effect of air pressure differential on vapor flow through sample building walls

    SciTech Connect

    Stewart, W.E. Jr.

    1998-12-31

    Laboratory scale experiments were performed on two small sample composite walls of typical building construction to determine the approximate opposing air pressure difference required to stop or significantly reduce the transmission of water vapor due to a water vapor pressure difference. The experiments used wall section samples between two controlled atmosphere chambers. One chamber was held at a temperature and humidity condition approximating that of a typical summer day, while the other chamber was controlled at a condition typical of indoor conditioned space. Vapor transmission data through the wall samples were obtained over a range of vapor pressure differentials and opposing air pressure differentials. The results show that increasing opposing air pressure differences decrease water vapor transmission, as expected, and relatively small opposing air pressure differentials are required for wall materials of small vapor permeability and large air permeability. The opposing air pressure that stopped or significantly reduced the flow of water vapor through the wall sample was determined experimentally and also compared to air pressures as predicted by an analytical model.

  11. Quantitative Assessment of Detection Frequency for the INL Ambient Air Monitoring Network

    SciTech Connect

    Sondrup, A. Jeffrey; Rood, Arthur S.

    2014-11-01

    Emission Standards for Hazardous Air Pollutants maximum exposed individual location (i.e., Frenchman’s Cabin) was no more than 0.1 mrem yr–1 (i.e., 1% of the 10 mrem yr–1 standard). Detection frequencies were calculated separately for the onsite and offsite monitoring network. As expected, detection frequencies were generally less for the offsite sampling network compared to the onsite network. Overall, the monitoring network is very effective at detecting the potential releases of Cs-137 or Sr-90 from all sources/facilities using either the ESER or BEA MDAs. The network was less effective at detecting releases of Pu-239. Maximum detection frequencies for Pu-239 using ESER MDAs ranged from 27.4 to 100% for onsite samplers and 3 to 80% for offsite samplers. Using BEA MDAs, the maximum detection frequencies for Pu-239 ranged from 2.1 to 100% for onsite samplers and 0 to 5.9% for offsite samplers. The only release that was not detected by any of the samplers under any conditions was a release of Pu-239 from the Idaho Nuclear Technology and Engineering Center main stack (CPP-708). The methodology described in this report could be used to improve sampler placement and detection frequency, provided clear performance objectives are defined.

  12. Development of a multiple objective planning theory and system for sustainable air quality monitoring networks.

    PubMed

    Chen, Ching-Ho; Liu, Wei-Lin; Chen, Chia-Hsing

    2006-01-15

    Air quality monitoring data are important bases for air quality management strategies planning and performance assessment. Therefore, the environmental protection authorities need to plan the air quality monitoring network effectively. However, in Taiwan, the national Environmental Protection Administration (EPA) and some county environmental protection bureaus (EPB) separately installed their own monitoring stations. This study developed an integrated methodology and computer system for planning air quality monitoring networks. The environmental, social, and economic objectives and sub-objectives, and their weights were identified using system analysis and multiple objective planning, based on the principles of sustainable development. A multiple objective optimization model and procedure for sustainable air quality monitoring networks planning are developed in this study. According to the procedure, a multiple objective planning system for sustainable air quality monitoring networks (MOPSSAQMN) is developed using computer software based on the modified bounded implicit enumeration algorithm with the constraint arrangement method. The air quality monitoring network of Taoyuan County, in northern Taiwan, was used as a case study to demonstrate the proposed method. Two satisfactory alternatives based on different conditions were generated using MOPSSAQMN. The compared results show that this study generated better alternatives than the current monitoring network. An installation schedule for the alternative was proposed, and its first step is now being implemented by the EPB of Taoyuan County Government. The procedure and computer system developed in this study can be used to assist the competent authorities to devise good and different alternatives for air quality monitoring networks planning.

  13. Fabrication and characterization of buckypapers for use in air sampling

    NASA Astrophysics Data System (ADS)

    Oh, Jonghwa

    Occupational exposure to volatile organic compounds (VOCs) is a concern from a public health perspective. In many industrial activities, workers' exposure to VOCs can be sufficiently high to induce adverse health effects, so their monitoring is necessary. In exposure assessment, post sampling extraction and quantification are the typical analytical procedures. Recently, our group developed the photothermal desorption (PTD) technique in which a pulse of light thermally desorbs an analyte directly from a sorbent. Advantages of this technique are; it is solvent free, repeated analysis is possible, sorbents are reusable, and no high cost of equipment is required. PTD overcomes almost all drawbacks of current extraction methods. This study was aimed to develop and test a new sorbent which will efficiently work with PTD. Single-walled carbon nanotubes (SWNTs) were examined as potential sorbents because of their high surface area, great thermal conductivity, and efficient light absorption. SWNTs were fabricated into a self-supporting form (i.e., buckypaper (BP)) which will preserve its physical integrity under normal working conditions. Largely two types of SWNTs were used, arc discharge (AD) and high-pressure carbon monoxide (HiPco), and different fabrication methods were examined. Upon fabrication, their adsorption properties were characterized in terms of Brunauer, Emmett, and Teller (BET) surface area, pore size, and toluene adsorption capacity. HiPco BP and methanol-cleaned AD BP (suspended/rinsed with methanol) were the top two materials, showing the highest surface area (649 and 387 m²/g, respectively) and adsorption capacity (106 and 46 mg/g, respectively) with relatively small mean pore diameter (7.7 and 8.8 nm, respectively). To further improve the adsorption properties, specific heat treatment conditions for each type of BPs were employed. After initial treatments only HiPco BP and acetone-cleaned AD BP (suspended/rinsed with acetone) were selected for further

  14. The variation of the relative humidity of air released from canisters after ambient sampling

    SciTech Connect

    McClenny, W.A.; Schmidt, S.M.; Kronmiller, K.G.

    1997-12-31

    Dalton`s Law of partial pressures and the hypothesis that water vapor equilibrium above a canister surface is identical to that established above liquid water are used to predict the variation of the percent relative humidity (%RH) of air released from canisters used in ambient air sampling, typically 6L canisters pressurized with 18L of air. During sampling, some water vapor is adsorbed on the canister wall. When (and if) the water vapor partial pressure exceeds its saturation vapor pressure, water vapor condensation begins and the condensation rate equals the sampling rate of water vapor into the canister. Under constant temperature conditions, the air subsequently released from the canister is less humid than the original sample, following the relationship, %RH = 100% (6L/V{sub s}) for V{sub s} > V{sub r} where V{sub s} is the residual air volume and V{sub r} is the residual air volume at which water is completely removed (except for adsorbed water vapor) from the canister wall. For V{sub s} < V{sub r} the %RH is constant and equal to its value at V{sub r}, V{sub r} is shown to depend on the %RH of the ambient air sample. Experimental values to agree reasonably well with predictions; however, experimental values were systematically lower than predicted especially when ambient air with mid-range %RH was sampled. This difference is related to the mass of water vapor remaining adsorbed on the canister surface as water evaporates. This paper has been reviewed in accordance with the U.S. Environmental Protection Agency`s peer and administrative review policies and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

  15. Stratospheric Air Sub-sampler (SAS) and its application to analysis of Δ17O(CO2) from small air samples collected with an AirCore

    NASA Astrophysics Data System (ADS)

    Janina Mrozek, Dorota; van der Veen, Carina; Hofmann, Magdalena E. G.; Chen, Huilin; Kivi, Rigel; Heikkinen, Pauli; Röckmann, Thomas

    2016-11-01

    We present the set-up and a scientific application of the Stratospheric Air Sub-sampler (SAS), a device to collect and to store the vertical profile of air collected with an AirCore (Karion et al., 2010) in numerous sub-samples for later analysis in the laboratory. The SAS described here is a 20 m long 1/4 inch stainless steel tubing that is separated by eleven valves to divide the tubing into 10 identical segments, but it can be easily adapted to collect smaller or larger samples. In the collection phase the SAS is directly connected to the outlet of an optical analyzer that measures the mole fractions of CO2, CH4 and CO from an AirCore sampler. The stratospheric part (or if desired any part of the AirCore air) is then directed through the SAS. When the SAS is filled with the selected air, the valves are closed and the vertical profile is maintained in the different segments of the SAS. The segments can later be analysed to retrieve vertical profiles of other trace gas signatures that require slower instrumentation. As an application, we describe the coupling of the SAS to an analytical system to determine the 17O excess of CO2, which is a tracer for photochemical processing of stratospheric air. For this purpose the analytical system described by Mrozek et al. (2015) was adapted for analysis of air directly from the SAS. The performance of the coupled system is demonstrated for a set of air samples from an AirCore flight in November 2014 near Sodankylä, Finland. The standard error for a 25 mL air sample at stratospheric CO2 mole fraction is 0.56 ‰ (1σ) for δ17O and 0.03 ‰ (1σ) for both δ18O and δ13C. Measured Δ17O(CO2) values show a clear correlation with N2O in agreement with already published data.

  16. Microbial counts and particulate matter levels in roadside air samples under skytrain stations, Bangkok, Thailand.

    PubMed

    Luksamijarulkul, Pipat; Kongtip, Pornpimol

    2010-05-01

    In conditions with heavy traffic and crowds of people on roadside areas under skytrain stations in Bangkok, the natural air ventilation may be insufficient and air quality may be poor. A study of 350 air samples collected from the roadside, under skytrain stations in Bangkok, was carried out to assess microbial counts (210 air samples) and particulate matter (PM10) levels (140 samples). The results reveal the mean +/- standard deviation bacterial counts and fungal counts were 406.8 +/- 302.7 cfu/m3 and 128.9 +/- 89.7 cfu/m3, respectively. The PM10 level was 186.1 +/- 188.1 microg/m3. When compared to recommended levels, 4.8% of air samples (10/210 samples) had bacterial counts more than recommended levels (> 1,000 cfu/ m3) and 27.1% (38/140 samples) had PM10 levels more than recommended levels (> 120 microg/m3). These may affect human health, especially of street venders who spend most of their working time in these areas.

  17. Marine Technician's Handbook, Instructions for Taking Air Samples on Board Ship: Carbon Dioxide Project.

    ERIC Educational Resources Information Center

    Keeling, Charles D.

    This booklet is one of a series intended to provide explicit instructions for the collection of oceanographic data and samples at sea. The methods and procedures described have been used by the Scripps Institution of Oceanography and found reliable and up-to-date. Instructions are given for taking air samples on board ship to determine the…

  18. Report on sampling and analysis of ambient air at the central waste complex

    SciTech Connect

    Stauffer, M., Fluor Daniel Hanford

    1997-02-13

    Over 160 ambient indoor air samples were collected from warehouses at the Central Waste Complex used for the storage of low- level radioactive and mixed wastes. These grab (SUMMA) samples were analyzed by gas chromatography-mass spectrometry using a modified EPA TO-14 procedure. The data from this survey suggest that several buildings had elevated concentrations of volatile organic compounds.

  19. DEVELOPMENT OF A SUB-SLAB AIR SAMPLING PROTOCOL TO SUPPORT ASSESSMENT OF VAPOR INTRUSION

    EPA Science Inventory

    The primary purpose of this research effort is to develop a methodology for sub-slab sampling to support the EPA guidance and vapor intrusion investigations after vapor intrusion has been established at a site. Methodologies for sub-slab air sampling are currently lacking in ref...

  20. Development of a multicopter-carried whole air sampling apparatus and its applications in environmental studies.

    PubMed

    Chang, Chih-Chung; Wang, Jia-Lin; Chang, Chih-Yuan; Liang, Mao-Chang; Lin, Ming-Ren

    2016-02-01

    To advance the capabilities of probing chemical composition aloft, we designed a lightweight remote-controlled whole air sampling component (WASC) and integrated it into a multicopter drone with agile maneuverability to perform aerial whole air sampling. A field mission hovering over an exhaust shaft of a roadway tunnel to collect air samples was performed to demonstrate the applicability of the multicopter-carried WASC apparatus. Ten aerial air samples surrounding the shaft vent were collected by the multicopter-carried WASC. Additional five samples were collected manually inside the shaft for comparison. These samples were then analyzed in the laboratory for the chemical composition of 109 volatile organic compounds (VOCs), CH4, CO, CO2, or CO2 isotopologues. Most of the VOCs in the upwind samples (the least affected by shaft exhaust) were low in concentrations (5.9 ppbv for total 109 VOCs), posting a strong contrast to those in the shaft exhaust (235.8 ppbv for total 109 VOCs). By comparing the aerial samples with the in-shaft samples for chemical compositions, the influence of the shaft exhaust on the surrounding natural air was estimated. Through the aerial measurements, three major advantages of the multicopter-carried WASC were demonstrated: 1. The highly maneuverable multicopter-carried WASC can be readily deployed for three-dimensional environmental studies at a local scale (0-1.5 km); 2. Aerial sampling with superior sample integrity and preservation conditions can now be performed with ease; and 3. Data with spatial resolution for a large array of gaseous species with high precision can be easily obtained.

  1. Radiocarbon analysis of stratospheric CO2 retrieved from AirCore sampling

    NASA Astrophysics Data System (ADS)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-10-01

    Radiocarbon (14C) is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases CO2 and CH4. Measurement of radiocarbon in atmospheric CO2 generally requires the collection of large air samples (a few liters) from which CO2 is extracted and then the concentration of radiocarbon is determined using accelerator mass spectrometry (AMS). However, the regular collection of air samples from the stratosphere, for example using aircraft and balloons, is prohibitively expensive. Here we describe radiocarbon measurements in stratospheric CO2 collected by the AirCore sampling method. AirCore is an innovative atmospheric sampling system, which comprises a long tube descending from a high altitude with one end open and the other closed, and it has been demonstrated to be a reliable, cost-effective sampling system for high-altitude profile (up to ≈ 30 km) measurements of CH4 and CO2. In Europe, AirCore measurements have been being performed on a regular basis near Sodankylä (northern Finland) since September 2013. Here we describe the analysis of samples from two such AirCore flights made there in July 2014, for determining the radiocarbon concentration in stratospheric CO2. The two AirCore profiles were collected on consecutive days. The stratospheric part of the AirCore was divided into six sections, each containing ≈ 35 µg CO2 ( ≈ 9.6 µgC), and stored in a stratospheric air subsampler constructed from 1/4 in. coiled stainless steel tubing ( ≈ 3 m). A small-volume extraction system was constructed that enabled > 99.5 % CO2 extraction from the stratospheric air samples. Additionally, a new small-volume high-efficiency graphitization system was constructed for graphitization of these extracted CO2 samples, which were measured at the Groningen AMS facility. Since the stratospheric samples were very similar in mass, reference samples were also prepared in the same mass range for

  2. Determination of radiocarbon in stratospheric CO2, obtained through AirCore sampling.

    NASA Astrophysics Data System (ADS)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-04-01

    The concentration of Greenhouse Gases (GHG), with carbon dioxide as the most prominent example, has been and still is increasing, predominantly due to emissions from fossil fuel combustion. CO2 is also the most important component of the global carbon cycle. Among other tracers, radiocarbon (Carbon-14) is a unique and an important atmospheric tracer used in the understanding of the global carbon cycle. Radiocarbon is a naturally occurring isotope (radioactive, t 1/2 = 5730 ± 40 years) of carbon produced through the interaction of thermalized neutrons and nitrogen in the upper atmosphere. Generally, for performing atmospheric radiocarbon measurements in the higher atmosphere, large samples (few liters of air) were collected using aircrafts and balloons. However, collecting stratospheric samples on a regular basis for radiocarbon analysis is extremely expensive. Here we describe the determination of radiocarbon concentrations in stratospheric CO2, collected using AirCore sampling. AirCore is an innovative sampling technique for obtaining vertical atmospheric profiles and, in Europe, is done on a regular basis at Sodankylä, Finland for CO2, CH4 and CO. The stratospheric parts of two such AirCore profiles were used in this study as a proof-of-principle. CO2 from the stratospheric air samples were extracted and converted to elemental carbon, which were then measured at the Accelerator Mass Spectrometric (AMS) facility of the Centre for Isotope Research (CIO) at the University of Groningen. The stratospheric part of the AirCore profile was divided into six sections, each contained approximately 10 μg C. A detailed description of the extraction, graphitization, AMS analysis and the derivation of the stratospheric radiocarbon profile will be the main focus. Through our results, we will show that AirCore is a viable sampling method for performing high-precision radiocarbon measurements of stratospheric CO2 with reasonably good spatial resolution on a regular basis

  3. Pesticide detection in air samples from contrasted houses and in their inhabitants' hair.

    PubMed

    Raeppel, Caroline; Salquèbre, Guillaume; Millet, Maurice; Appenzeller, Brice M R

    2016-02-15

    In order to identify associations between indoor air contamination and human exposure to pesticides, hair samples from 14 persons (9 adults and 5 children below 12 years) were collected simultaneously with the air of their 5 contrasted houses. Three houses were situated in Alsace (France), one in Lorraine (France) and one in Luxembourg (Luxembourg). Houses were located in urban (n=3), semi-urban (n=1) and rural areas (n=1). Twenty five (25) pesticides were detected at least once in indoor air samples and 20 pesticides were detected at least once in hair samples. The comparison between hair and air samples for the same sampling periods shows that pesticides detected in the two matrices were not necessarily associated. Exposure profiles varied from one home to another but also between inhabitants of the same home, suggesting that exposure can be different between inhabitants of the same home. This study demonstrated the usefulness and the complementarity of hair analysis, for the personalized biomonitoring of people exposure to pesticides, and air analysis, for the identification of airborne exposure and house contamination.

  4. Comparison of mold concentrations quantified by MSQPCR in indoor and outdoor air sampled simultaneously

    SciTech Connect

    Meklin, Teija; Reponen, Tina; McKinstry, Craig A.; Cho, Seung H.; Grinshpun, Sergey A.; Nevalainen, Aino; Vepsalainen, Asko; Haugland, Richard A.; Lemasters, Grace; Vesper, Sephen J.

    2007-08-15

    Mold specific quantitative PCR (MSQPCR) was used to measure the concentrations of 36 mold species in dust and in indoor and in outdoor air samples that were taken simultaneously in 17 homes in Cincinnati with no-known water damage. The total spore concentrations in the indoor (I) and outdoor (O) air samples were statistically significantly different and the concentrations in the three sample types of many of the individual species were significantly different (p < 0.05 based on the Wilcoxon Signed Rank Test). The I/O ratios of the averages or geometric means of the individual species were generally less than 1; but these I/O ratios were quite variable ranging from 0.03 for A. sydowii to 1.2 for Acremonium strictum. There were no significant correlations for the 36 specific mold concentrations between the dust samples and the indoor or outdoor air samples (based on the Spearman’s Rho test). The indoor and outdoor air concentrations of 32 of the species were not correlated. Only Aspergillus penicillioides, C. cladosporioides types 1 and 2 and C. herbarum had sufficient data to estimate a correlation at rho > 0.5 with signicance (p < 0.05) In six of these homes, a previous dust sample had been collected and analyzed 2 years earlier. The ERMI© values for the dust samples taken in the same home two years apart were not significantly different (p=0.22) based on Wilcoxon Signed Rank Test.

  5. Field evaluation of sampling and analysis for organic pollutants in indoor air

    SciTech Connect

    Chuang, J.C.; Mack, G.A.; Stockrahm, J.W.; Hannan, S.W.; Bridges, C.

    1988-08-01

    The objectives of the study were to determine the feasibility of the use of newly developed indoor air samplers in residential indoor air sampling and to evaluate methodology for characterization of the concentrations of polynuclear aromatic hydrocarbons (PAH), PAH derivatives, and nicotine in residential air. Residential air sampling was conducted in Columbus, Ohio during the winter of 1986/87. The PAH derivatives were found at much lower levels than their parent PAH. Higher average indoor levels of all but three target compounds were found compared to outdoor levels. The higher outdoor levels of these three compounds (naphthalene dicarboxylic acid anhydride, pyrene dicarboxylic acid anhydride, and 2-nitrofluoranthene) are probably due to atmospheric transformation. Cigarette smoking was identified as the most-significant contributor to indoor levels of PAH and PAH derivatives. Homes with gas-heating systems appeared to have higher pollutant levels compared to homes with electric-heating systems.

  6. Air Sample Conditioner Helps the Waste Treatment Plant Meet Emissions Standards

    SciTech Connect

    Glissmeyer, John A.; Flaherty, Julia E.; Pekour, Mikhail S.

    2014-12-02

    The air in three of the Hanford Site Waste Treatment and Immobilization Plant (WTP) melter off-gas discharge stacks will be hot and humid after passing through the train of emission abatement equipment. The off-gas temperature and humidity levels will be incompatible with the airborne emissions monitoring equipment required for this type of stack. To facilitate sampling from these facilities, an air sample conditioner system will be installed to introduce cool, dry air into the sample stream to reduce the temperature and dew point. This will avoid thermal damage to the instrumentation and problematic condensation. The complete sample transport system must also deliver at least 50% of the particles in the sample airstream to the sample collection and on-line analysis equipment. The primary components of the sample conditioning system were tested in a laboratory setting. The sample conditioner itself is based on a commercially-available porous tube filter design. It consists of a porous sintered metal tube inside a coaxial metal jacket. The hot gas sample stream passes axially through the porous tube, and the dry, cool air is injected into the jacket and through the porous wall of the inner tube, creating an effective sample diluter. The dilution and sample air mix along the entire length of the porous tube, thereby simultaneously reducing the dew point and temperature of the mixed sample stream. Furthermore, because the dilution air enters through the porous tube wall, the sample stream does not come in contact with the porous wall and particle deposition is reduced in this part of the sampling system. Tests were performed with an environmental chamber to supply air with the temperature and humidity needed to simulate the off-gas conditions. Air from the chamber was passed through the conditioning system to test its ability to reduce the temperature and dew point of the sample stream. To measure particle deposition, oil droplets in the range of 9 to 11 micrometer

  7. Note: Design and development of wireless controlled aerosol sampling network for large scale aerosol dispersion experiments

    SciTech Connect

    Gopalakrishnan, V.; Subramanian, V.; Baskaran, R.; Venkatraman, B.

    2015-07-15

    Wireless based custom built aerosol sampling network is designed, developed, and implemented for environmental aerosol sampling. These aerosol sampling systems are used in field measurement campaign, in which sodium aerosol dispersion experiments have been conducted as a part of environmental impact studies related to sodium cooled fast reactor. The sampling network contains 40 aerosol sampling units and each contains custom built sampling head and the wireless control networking designed with Programmable System on Chip (PSoC™) and Xbee Pro RF modules. The base station control is designed using graphical programming language LabView. The sampling network is programmed to operate in a preset time and the running status of the samplers in the network is visualized from the base station. The system is developed in such a way that it can be used for any other environment sampling system deployed in wide area and uneven terrain where manual operation is difficult due to the requirement of simultaneous operation and status logging.

  8. Note: Design and development of wireless controlled aerosol sampling network for large scale aerosol dispersion experiments

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, V.; Subramanian, V.; Baskaran, R.; Venkatraman, B.

    2015-07-01

    Wireless based custom built aerosol sampling network is designed, developed, and implemented for environmental aerosol sampling. These aerosol sampling systems are used in field measurement campaign, in which sodium aerosol dispersion experiments have been conducted as a part of environmental impact studies related to sodium cooled fast reactor. The sampling network contains 40 aerosol sampling units and each contains custom built sampling head and the wireless control networking designed with Programmable System on Chip (PSoC™) and Xbee Pro RF modules. The base station control is designed using graphical programming language LabView. The sampling network is programmed to operate in a preset time and the running status of the samplers in the network is visualized from the base station. The system is developed in such a way that it can be used for any other environment sampling system deployed in wide area and uneven terrain where manual operation is difficult due to the requirement of simultaneous operation and status logging.

  9. Note: Design and development of wireless controlled aerosol sampling network for large scale aerosol dispersion experiments.

    PubMed

    Gopalakrishnan, V; Subramanian, V; Baskaran, R; Venkatraman, B

    2015-07-01

    Wireless based custom built aerosol sampling network is designed, developed, and implemented for environmental aerosol sampling. These aerosol sampling systems are used in field measurement campaign, in which sodium aerosol dispersion experiments have been conducted as a part of environmental impact studies related to sodium cooled fast reactor. The sampling network contains 40 aerosol sampling units and each contains custom built sampling head and the wireless control networking designed with Programmable System on Chip (PSoC™) and Xbee Pro RF modules. The base station control is designed using graphical programming language LabView. The sampling network is programmed to operate in a preset time and the running status of the samplers in the network is visualized from the base station. The system is developed in such a way that it can be used for any other environment sampling system deployed in wide area and uneven terrain where manual operation is difficult due to the requirement of simultaneous operation and status logging.

  10. Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schindler, Matthias; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

    2016-05-01

    Three new methods to sample and prepare various carbonyl compounds for radiocarbon measurements were developed and tested. Two of these procedures utilized the Strecker synthetic method to form amino acids from carbonyl compounds with either sodium cyanide or trimethylsilyl cyanide. The third procedure used semicarbazide to form crystalline carbazones with the carbonyl compounds. The resulting amino acids and semicarbazones were then separated and purified using thin layer chromatography. The separated compounds were then combusted to CO2 and reduced to graphite to determine 14C content by accelerator mass spectrometry (AMS). All of these methods were also compared with the standard carbonyl compound sampling method wherein a compound is derivatized with 2,4-dinitrophenylhydrazine and then separated by high-performance liquid chromatography (HPLC).

  11. The combined effects of sampling parameters on the sorbent tube sampling of phthalates in air

    PubMed Central

    Jo, Sang-Hee; Kim, Ki-Hyun; Kwon, Kyenghee

    2017-01-01

    The adsorption properties of various sorbent materials were investigated to assess the factors affecting biases in the sorbent tube (ST) sampling of airborne phthalates. The recovery of phthalates was assessed critically in relation to four key sampling parameters: (1) three types of sorbent materials (quartz wool (QW), glass wool (GW), and quartz wool plus Tenax TA (QWTN)), (2) the concentration level of phthalate standards, (3) purge flow rate, and (4) purge volume for analysis based on a ‘sorbent tube-thermal desorption-gas chromatography-mass spectrometry (ST-TD-GC-MS)’ system. Among these parameters, the type of ST was the most influential in determining the recovery of phthalates. For a given ST type, the recovery of phthalates tends to improve with increases in the concentration level of standards. In case of QW and QWTN tubes, the breakthrough of phthalates was not observed up to the maximum purge volume (100 L) tested in this work; however, in case of GW, the recovery decreased drastically to 60% even at a purge volume of 1 L for low molecular weight phthalates. The results of our study demonstrate that accurate analysis of airborne phthalates can be achieved through proper control of key sampling parameters, particularly the choice of sorbent material. PMID:28361993

  12. Air bearing center cross gap of neutron stress spectrometer sample table support system

    NASA Astrophysics Data System (ADS)

    Li, Yang; Wu, Yunxin; Gong, Hai; Feng, Xiaolei

    2016-12-01

    A support system is the main load-bearing component of sample table for neutron stress spectrometer, and air bearing is an important element of a support system. The neutron stress spectrometer sample table was introduced, and the scheme for air bearing combination was selected. To study the performance of air bearing center cross gap, finite element models (FEMs) were established based on air motion and Reynolds equations, effects of air supply pressure, and gap parameters on the overturning moment and bearing capacity of air bearing center cross gap were analyzed. Results indicate that the width, depth, and height differences of the marble floor gap played important roles in the performance of the air bearing. When gap width is lesser than 1 mm and gap depth is lower than 0.4 mm, bearing capacity and overturning moment would vary rapidly with the variation of the width and depth. A gap height difference results in the bearing capacity dropping rapidly. The FEM results agree well with experimental results. Further, findings of the study could guide the design of the support system and marble floor.

  13. Sampling technologies and air pollution control devices for gaseous and particulate arsenic: a review.

    PubMed

    Helsen, Lieve

    2005-09-01

    Direct measurement of arsenic release requires a good sampling and analysis procedure in order to capture and detect the total amount of metals emitted. The literature is extensively reviewed in order to evaluate the efficiency of full field-scale and laboratory scale techniques for capturing particulate and gaseous emissions of arsenic from the thermo-chemical treatment of different sources of arsenic. Furthermore, trace arsenic concentrations in ambient air, national standard sampling methods and arsenic analysis methods are considered. Besides sampling techniques, the use of sorbents is also reviewed with respect to both approaches (1) to prevent the metals from exiting with the flue gas and (2) to react or combine with the metals in order to be collected in air pollution control systems. The most important conclusion is that submicron arsenic fumes are difficult to control in conventional air pollution control devices. Complete capture of the arsenic species requires a combination of particle control and vapour control devices.

  14. Use of a Radon Stripping Algorithm for Retrospective Assessment of Air Filter Samples

    SciTech Connect

    Robert Hayes

    2009-01-23

    An evaluation of a large number of air sample filters was undertaken using a commercial alpha and beta spectroscopy system employing a passive implanted planar silicon (PIPS) detector. Samples were only measured after air flow through the filters had ceased. Use of a commercial radon stripping algorithm was implemented to discriminate anthropogenic alpha and beta activity on the filters from the radon progeny. When uncontaminated air filters were evaluated, the results showed that there was a time-dependent bias in both average estimates and measurement dispersion with the relative bias being small compared to the dispersion. By also measuring environmental air sample filters simultaneously with electroplated alpha and beta sources, use of the radon stripping algorithm demonstrated a number of substantial unexpected deviations. Use of the current algorithm is therefore not recommended for assay applications and so use of the PIPS detector should only be utilized for gross counting without appropriate modifications to the curve fitting algorithm. As a screening method, the radon stripping algorithm might be expected to see elevated alpha and beta activities on air sample filters (not due to radon progeny) around the 200 dpm level.

  15. Mitigating factors on air concentrations of radon emanating from different granite samples

    SciTech Connect

    Qari, T.M.; Mamoon, A.M.; Abdul-Fattah, A.F. )

    1991-11-01

    Continuous exposure to increased air concentrations of radon in living areas is to be avoided according to the Environmental Protection Agency (EPA) and several published reports. Radon concentrations in ambient air are influenced by several factors related to the nature of the radon source itself, environmental conditions, and the presence of mitigating factors, if any. In this study, crushed granite samples of different types, particle diameters, and moisture contents were compared in simplified test systems with regard to radon emanation from the samples. The effects of selected mitigating factors, namely, ventilation and different barriers to diffusion of emanated radon were determined.

  16. Cleanliness of common air sampling sorbents for application to phenolic compounds measurement using supercritical fluid extraction

    SciTech Connect

    Bowyer, J.R.; Pleil, J.D.

    1994-12-31

    The trace-level measurement of phenolic compounds in the ambient air is complicated by the acidic and polar nature of the compounds especially during recovery from the sampling medium. Recently, supercritical fluid extraction (SFE) has been proposed as an alternative extraction method to Soxhlet extraction or thermal desorption to achieve more efficient recoveries. For such methodology to become practical, the candidate sorbents must first be tested for stability and cleanliness under SFE conditions. This paper describes exploratory research results of background contamination tests and cleanup properties of some common air sampling sorbent media with respect to future application to phenolic compounds monitoring.

  17. Cleanliness of common air sampling sorbents for application to phenolic compounds measurement using supercritical fluid extraction

    SciTech Connect

    Bowyer, J.R.; Pleil, J.D.

    1994-01-01

    The trace-level measurement of phenolic compounds in the ambient air is complicated by the acidic and polar nature of the compounds especially during recovery from the sampling medium. Recently, supercritical fluid extraction (SFE) has been proposed as an alternative extraction method to Soxhlet extraction or thermal desorption to achieve more efficient recoveries. For such methodology to become practical, the candidate sorbents must first be tested for stability and cleanliness under SFE conditions. The paper describes exploratory research results of background contamination tests and cleanup properties of some common air sampling sorbent media with respect to future application to phenolic compounds monitoring.

  18. Detection of Mycoplasma hyopneumoniae by Air Sampling with a Nested PCR Assay

    PubMed Central

    Stärk, Katharina D. C.; Nicolet, Jacques; Frey, Joachim

    1998-01-01

    This article describes the first successful detection of airborne Mycoplasma hyopneumoniae under experimental and field conditions with a new nested PCR assay. Air was sampled with polyethersulfone membranes (pore size, 0.2 μm) mounted in filter holders. Filters were processed by dissolution and direct extraction of DNA for PCR analysis. For the PCR, two nested pairs of oligonucleotide primers were designed by using an M. hyopneumoniae-specific DNA sequence of a repeated gene segment. A nested PCR assay was developed and used to analyze samples collected in eight pig houses where respiratory problems had been common. Air was also sampled from a mycoplasma-free herd. The nested PCR was highly specific and 104 times as sensitive as a one-step PCR. Under field conditions, the sampling system was able to detect airborne M. hyopneumoniae on 80% of farms where acute respiratory disease was present. No airborne M. hyopneumoniae was detected on infected farms without acute cases. The chance of successful detection was increased if air was sampled at several locations within a room and at a lower air humidity. PMID:9464391

  19. Passive dosimeters for nitrogen dioxide in personal/indoor air sampling: A review

    PubMed Central

    Yu, Chang Ho; Morandi, Maria T.; Weisel, Clifford P.

    2015-01-01

    Accurate measurement of nitrogen dioxide concentrations in both outdoor and indoor environments, including personal exposures, is a fundamental step for linking atmospheric nitrogen dioxide levels to potential health and ecological effects. The measurement has been conducted generally in two ways: active (pumped) sampling and passive (diffusive) sampling. Diffusion samplers, initially developed and used for workplace air monitoring, have been found to be useful and cost-effective alternatives to conventional pumped samplers for monitoring ambient, indoor and personal exposures at the lower concentrations found in environmental settings. Since the 1970s, passive samplers have been deployed for ambient air monitoring in urban and rural sites, and to determine personal and indoor exposure to NO2. This article reviews the development of NO2 passive samplers, the sampling characteristics of passive samplers currently available, and their application in ambient and indoor air monitoring and personal exposure studies. The limitations and advantages of the various passive sampler geometries (i.e., tube, badge, and radial type) are also discussed. This review provides researchers and risk assessors with practical information about NO2 passive samplers, especially useful when designing field sampling strategies for exposure and indoor/outdoor air sampling. PMID:18446185

  20. Air-sampling inlet contamination by aircraft emissions on the NASA CV-990 aircraft

    NASA Technical Reports Server (NTRS)

    Condon, E. P.; Vedder, J. F.

    1984-01-01

    Results of an experimental investigation of the contamination of air sampling inlets by aircraft emissions from the NASA CV-990 research aircraft are presented. This four-engine jet aircraft is a NASA facility used for many different atmospheric and meteorological experiments, as well as for developing spacecraft instrumentation for remote measurements. Our investigations were performed to provide information on which to base the selection of sampling locations for a series of multi-instrument missions for measuring tropospheric trace gases. The major source of contamination is the exhaust from the jet engines, which generate many of the same gases that are of interest in atmospheric chemistry, as well as other gases that may interfere with sampling measurements. The engine exhaust contains these gases in mixing ratios many orders of magnitude greater than those that occur in the clean atmosphere which the missions seek to quantify. Pressurized samples of air were collected simultaneously from a scoop located forward of the engines to represent clean air and from other multiport scoops at various aft positions on the aircraft. The air samples were analyzed in the laboratory by gas chromatography for carbon monoxide, an abundant combustion by-product. Data are presented for various scoop locations under various flight conditions.

  1. Network Centric Operations Conceptual Framework Air-to-Ground Case Study

    DTIC Science & Technology

    2004-06-01

    Network Centric Operations Conceptual Framework Air-to-Ground Case Study Final Brief 17 June 2004 Prepared by SAIC for: Evidence Based Research...JUN 2004 2. REPORT TYPE 3. DATES COVERED 00-00-2004 to 00-00-2004 4. TITLE AND SUBTITLE Network Centric Operations Conceptual Framework Air-to... conceptual framework which drove approach Cognitive Social Interviews to provide insights into cognitive process Assumptions OEF and OIF would

  2. Solubility testing of actinides on breathing-zone and area air samples

    SciTech Connect

    Metzger, R.L.; Jessop, B.H.; McDowell, B.L.

    1996-02-01

    A solubility testing method for several common actinides has been developed with sufficient sensitivity to allow profiles to be determined from routine breathing zone and area air samples in the workplace. Air samples are covered with a clean filter to form a filter-sample-filter sandwich which is immersed in an extracellular lung serum simulant solution. The sample is moved to a fresh beaker of the lung fluid simulant each day for one week, and then weekly until the end of the 28 day test period. The soak solutions are wet ashed with nitric acid and hydrogen peroxide to destroy the organic components of the lung simulant solution prior to extraction of the nuclides of interest directly into an extractive scintillator for subsequent counting on a Photon-Electron Rejecting Alpha Liquid Scintillation (PERALS{reg_sign}) spectrometer. Solvent extraction methods utilizing the extractive scintillators have been developed for the isotopes of uranium, plutonium, and curium. The procedures normally produce an isotopic recovery greater than 95% and have been used to develop solubility profiles from air samples with 40 pCi or less of U{sub 3}O{sub 8}. Profiles developed for U{sub 3}O{sub 8} samples show good agreement with in vitro and in vivo tests performed by other investigators on samples from the same uranium mills.

  3. Twenty years of measurement of polycyclic aromatic hydrocarbons (PAHs) in UK ambient air by nationwide air quality networks.

    PubMed

    Brown, Andrew S; Brown, Richard J C; Coleman, Peter J; Conolly, Christopher; Sweetman, Andrew J; Jones, Kevin C; Butterfield, David M; Sarantaridis, Dimitris; Donovan, Brian J; Roberts, Ian

    2013-06-01

    The impact of human activities on the health of the population and of the wider environment has prompted action to monitor the presence of toxic compounds in the atmosphere. Toxic organic micropollutants (TOMPs) are some of the most insidious and persistent of these pollutants. Since 1991 the United Kingdom has operated nationwide air quality networks to assess the presence of TOMPs, including polycyclic aromatic hydrocarbons (PAHs), in ambient air. The data produced in 2010 marked 20 years of nationwide PAH monitoring. This paper marks this milestone by providing a novel and critical review of the data produced since nationwide monitoring began up to the end of 2011 (the latest year for which published data is available), discussing how the networks performing this monitoring has evolved, and elucidating trends in the concentrations of the PAHs measured. The current challenges in the area and a forward look to the future of air quality monitoring for PAHs are also discussed briefly.

  4. Pumping tests in networks of multilevel sampling wells: Motivation and methodology

    USGS Publications Warehouse

    Butler, J.J.; McElwee, C.D.; Bohling, G.C.

    1999-01-01

    The identification of spatial variations in hydraulic conductivity (K) on a scale of relevance for transport investigations has proven to be a considerable challenge. Recently, a new field method for the estimation of interwell variations in K has been proposed. This method, hydraulic tomography, essentially consists of a series of short-term pumping tests performed in a tomographic-like arrangement. In order to fully realize the potential of this approach, information about lateral and vertical variations in pumping-induced head changes (drawdown) is required with detail that has previously been unobtainable in the field. Pumping tests performed in networks of multilevel sampling (MLS) wells can provide data of the needed density if drawdown can accurately and rapidly be measured in the small-diameter tubing used in such wells. Field and laboratory experiments show that accurate transient drawdown data can be obtained in the small-diameter MLS tubing either directly with miniature fiber-optic pressure sensors or indirectly using air-pressure transducers. As with data from many types of hydraulic tests, the quality of drawdown measurements from MLS tubing is quite dependent on the effectiveness of well development activities. Since MLS ports of the standard design are prone to clogging and are difficult to develop, alternate designs are necessary to ensure accurate drawdown measurements. Initial field experiments indicate that drawdown measurements obtained from pumping tests performed in MLS networks have considerable potential for providing valuable information about spatial variations in hydraulic conductivity.

  5. Community Air Sensor Network (CAIRSENSE) Project: Lower Cost, Continuous Ambient Monitoring Methods

    EPA Science Inventory

    Advances in air pollution sensor technology have enabled the development of small and low cost systems to measure outdoor air pollution. The deployment of numerous sensors across a small geographic area would have potential benefits to supplement existing monitoring networks and ...

  6. Journal Article: EPA's National Dioxin Air Monitoring Network (Ndamn): Design, Implementation, and Final Results

    EPA Science Inventory

    The U.S. Environmental Protection Agency (U.S. EPA) established the National Dioxin Air Monitoring Network (NDAMN) in June of 1998, and operated it until November of 2004. The objective of NDAMN was to determine background air concentrations of polychlorinated dibenzo-p-dioxins (...

  7. Professional judgment and the interpretation of viable mold air sampling data.

    PubMed

    Johnson, David; Thompson, David; Clinkenbeard, Rodney; Redus, Jason

    2008-10-01

    Although mold air sampling is technically straightforward, interpreting the results to decide if there is an indoor source is not. Applying formal statistical tests to mold sampling data is an error-prone practice due to the extreme data variability. With neither established exposure limits nor useful statistical techniques, indoor air quality investigators often must rely on their professional judgment, but the lack of a consensus "decision strategy" incorporating explicit decision criteria requires professionals to establish their own personal set of criteria when interpreting air sampling data. This study examined the level of agreement among indoor air quality practitioners in their evaluation of airborne mold sampling data and explored differences in inter-evaluator assessments. Eighteen investigators independently judged 30 sets of viable mold air sampling results to indicate: "definite indoor mold source," "likely indoor mold source," "not enough information to decide," "likely no indoor mold source," or "definitely no indoor mold source." Kappa coefficient analysis indicated weak inter-observer reliability, and comparison of evaluator mean scores showed clear inter-evaluator differences in their overall scoring patterns. The responses were modeled on indicator "traits" of the data sets using a generalized, linear mixed model approach and showed several traits to be associated with respondents' ratings, but they also demonstrated distinct and divergent inter-evaluator response patterns. Conclusions were that there was only weak overall agreement in evaluation of the mold sampling data, that particular traits of the data were associated with the conclusions reached, and that there were substantial inter-evaluator differences that were likely due to differences in the personal decision criteria employed by the individual evaluators. The overall conclusion was that there is a need for additional work to rigorously explore the constellation of decision criteria

  8. Measured phenol concentrations in air and rain water samples collected near a wood preserving facility

    SciTech Connect

    Allen, S.K.; Allen, C.W.

    1995-12-31

    Phenol concentrations were determined in air and rain water samples collected downwind from a coal tar creosote wood preserving facility in Terre Haute, IN. Coal tar creosote is known to contain a large number of constituents and is composed chiefly of polycyclic aromatic hydrocarbons (PAH), phenols, and N-, S-, and O-heterocycles. Phenol was chosen as a marker compound for coal tar creosote emissions because it is present at a large mole fraction in coal tar creosote. Phenol was determined by HPLC with UV-Visible detection. Phenol in collected rain water samples was determined directly by HPLC after acidification and filtration. Phenol concentrations in collected air samples ranged from 4.1 to 15.7 {micro}g/m3 while rain water concentrations ranged from 7.9 to 28.2 {micro}g/L. Using a value for the thermodynamic Henry`s law constant of K{sub H} = 4.5 {times} 10{sup {minus}4} L atm/mole at 20 C for phenol and measured gas-phase phenol concentrations, even higher rain water concentrations would be expected if equilibrium was established. This indicates that the amount of phenol present in the air parcels sampled exceeded the amount that could be scavenged by rain drops under the conditions prevailing at the time of sampling. The values for phenol concentrations reported here are roughly two orders of magnitude higher than results from previous studies where phenol concentrations in air and rain water samples collected in urban areas were reported. It is likely that other more toxic constituents of coal tar creosote are also present at high concentrations in air parcels that receive emissions from wood treatment facilities.

  9. Development and calibration of real-time PCR for quantification of airborne microorganisms in air samples

    NASA Astrophysics Data System (ADS)

    An, Hey Reoun; Mainelis, Gediminas; White, Lori

    This manuscript describes the coupling of bioaerosol collection and the use of real-time PCR (RT-PCR) to quantify the airborne bacteria. The quantity of collected bacteria determined by RT-PCR is compared with conventional quantification techniques, such as culturing, microscopy and airborne microorganism counting by using optical particle counter (OPC). Our data show that an experimental approach used to develop standard curves for use with RT-PCR is critical for accurate sample quantification. Using universal primers we generated 12 different standard curves which were used to quantify model organism Escherichia coli (Migula) Catellani from air samples. Standard curves prepared using a traditional approach, where serially diluted genomic DNA extracted from pure cultured bacteria were used in PCR reaction as a template DNA yielded significant underestimation of sample quantities compared to airborne microorganism concentration as measured by an OPC. The underestimation was especially pronounced when standard curves were built using colony forming units (CFUs). In contrast, the estimate of cell concentration in an air sample by RT-PCR was more accurate (˜60% compared to the airborne microorganism concentration) when the standard curve was built using aerosolized E. coli. The accuracy improved even further (˜100%) when air samples used to build the standard curves were diluted first, then the DNA extracted from each dilution was amplified by the RT-PCR—to mimic the handling of air samples with unknown and possibly low concentration. Therefore, our data show that standard curves used for quantification by RT-PCR needs to be prepared using the same environmental matrix and procedures as handling of the environmental sample in question. Reliance on the standard curves generated with cultured bacterial suspension (a traditional approach) may lead to substantial underestimation of microorganism quantities in environmental samples.

  10. The effect of compressed air foam on the detection of hydrocarbon fuels in fire debris samples.

    PubMed

    Coulson, S A; Morgan-Smith, R K; Noble, D

    2000-01-01

    In 1998/99 the New Zealand Fire Service implemented compressed air foam delivery systems for the suppression of fires in rural areas. This study investigated whether the introduction of the foam to the seat of the fire created any problems in subsequent analyses of fire debris samples. No significant interferences from the foam were found when the samples were analysed by direct headspace using activated carbon strips. The only foam component detected was limonene.

  11. Air and smear sample calculational tool for Fluor Hanford Radiological control

    SciTech Connect

    BAUMANN, B.L.

    2003-07-11

    A spreadsheet calculation tool was developed to automate the calculations performed for determining the concentration of airborne radioactivity and smear counting as outlined in HNF-13536, Section 5.2.7, ''Analyzing Air and Smear Samples''. This document reports on the design and testing of the calculation tool. Radiological Control Technicians (RCTs) will save time and reduce hand written and calculation errors by using an electronic form for documenting and calculating work place air samples. Current expectations are RCTs will perform an air sample and collect the filter or perform a smear for surface contamination. RCTs will then survey the filter for gross alpha and beta/gamma radioactivity and with the gross counts utilize either hand calculation method or a calculator to determine activity on the filter. The electronic form will allow the RCT with a few key strokes to document the individual's name, payroll, gross counts, instrument identifiers; produce an error free record. This productivity gain is realized by the enhanced ability to perform mathematical calculations electronically (reducing errors) and at the same time, documenting the air sample.

  12. Technical assessment of workplace air sampling requirements at tank farm facilities. Revision 2

    SciTech Connect

    Olsen, P.A.; Brown, R.L.

    1995-03-22

    Tank Farm facilities compliance with the workplace air sampling (WPAS) program has been assessed. Requirements bases for determining compliance and recommendations are included. In the current condition all buildings are in compliance with the WPAS program. This document also supersedes WHC-SD-SQA-TA-20012, revision 0.

  13. Modeling and Qualification of a Modified Emission Unit for Radioactive Air Emissions Stack Sampling Compliance

    SciTech Connect

    Barnett, J. Matthew; Yu, Xiao-Ying; Recknagle, Kurtis P.; Glissmeyer, John A.

    2016-01-01

    A planned laboratory space and exhaust system modification to the Pacific Northwest National Laboratory Material Science and Technology Building indicated a new evaluation of the mixing at the air sampling system location would be required for compliance to ANSI/HPS N13.1-2011. The modified exhaust system would add a third fan thereby increasing the overall exhaust rate out the stack thus voiding the previous mixing study. Prior to modifying the radioactive air emissions exhaust system, a three-dimensional computational fluid dynamics computer model was used to evaluate the mixing at the sampling system location. Modeling of the new original three-fan system indicated that not all mixing criteria could be met. A second modeling effort was conducted with the addition of an air blender downstream of the confluence of the three fans which then showed satisfactory mixing results. The final installation included an air blender, and the exhaust system underwent full-scale tests to verify velocity, cyclonic flow, gas, and particulate uniformity. The modeling results and those of the full-scale tests show agreement between each of the evaluated criteria. The use of a computational fluid dynamics code was an effective aid in the design process and allowed the sampling system to remain in its original location while still meeting the requirements for sampling at a well-mixed location.

  14. COMPARISON OF FAST GC/TOFMS WITH METHOD TO-14 FOR ANALYSIS OF AMBIENT AIR SAMPLES

    EPA Science Inventory

    Field studies using portable gas chromatographs (PGC) to analyze volatile organic compounds in ambient air usually include, as reference standard method, the analysis of concurrent, collocated canister samples by EPA Method TO-14. Each laboratory analysis takes about an hour a...

  15. COMPARISON OF MOLD CONCENTRATIONS IN INDOOR AND OUTDOOR AIR SAMPLED SIMULTANEOUSLY AND THEN QUANTIFIED BY MSQPCR

    EPA Science Inventory

    Mold specific quantitative PCR (MSQPCR) was used to measure the concentrations of the 36 mold species in indoor and outdoor air samples that were taken simultaneously for 48 hours in and around 17 homes in Cincinnati, Ohio. The total spore concentrations of 353 per m3...

  16. Development of a wireless air pollution sensor package for aerial-sampling of emissions

    EPA Science Inventory

    A new sensor system for mobile and aerial emission sampling was developed for open area pollutant sources, such as prescribed forest burns. The sensor system, termed “Kolibri”, consists of multiple low-cost air quality sensors measuring CO2, CO, samplers for particulate matter wi...

  17. Collecting Samples of Workplace Air. Module 8. Vocational Education Training in Environmental Health Sciences.

    ERIC Educational Resources Information Center

    Consumer Dynamics Inc., Rockville, MD.

    This module, one of 25 on vocational education training for careers in environmental health occupations, contains self-instructional materials on collecting samples of workplace air. Following guidelines for students and instructors and an introduction that explains what the student will learn are three lessons: (1) collecting information about…

  18. Ten-year air sample analysis of Aspergillus prevalence in a university hospital.

    PubMed

    Falvey, D G; Streifel, A J

    2007-09-01

    Airborne fungal samples were collected on a monthly basis for 10 years, from 1995 to 2005, at a tertiary university hospital. Paired samples were cultured at 25 and 37 degrees C. Data were interpreted according to the air filtration systems serving each location. Samples cultured at 37 degrees C from the patient care areas had a mean recovery of 18% of the mean recovery from outdoor air (22 versus 122cfu/m(3)). Recovery of Aspergillus spp. at 37 degrees C in the high-efficiency particulate air (HEPA)-filtered locations was positive for Aspergillus spp. approximately one-third of the time; the rest of the patient care areas were positive half of the time and the outdoor samples were positive 95% of the time. We found 48 sporadic bursts at 37 degrees C which produced counts >3 SD above the mean. Hospital-acquired infection was related to high recovery of Aspergillus fumigatus on at least one occasion. We have found it impossible, without implementing impractical measures, to provide an environment completely devoid of Aspergillus spp. We conclude that routine air sampling is not an effective means of predicting hospital-acquired infections. However, a transient spike, or burst, may be useful in identifying an in-house source of contamination and may be used to consider additional interventional treatments for patients at risk. Emphasis should be placed on maintaining high-efficiency filtration of the outside air and on ensuring that other environmental control methods are used to prevent dissemination of environmental opportunistic fungal spores.

  19. The U.S. Air Force Academy Falcon Telescope Network

    DTIC Science & Technology

    2014-09-05

    The Falcon Telescope Network (FTN) is a global network of small aperture telescopes developed by the Center for Space Situational Awareness Research...equipment (e.g. telescope , mount, camera, filter wheel, dome, weather stations, computers and storage devices) while the educational partners provide...After an observational request is completed, the FTN user will receive notification of collection and a link to the data. The Falcon Telescope Network

  20. Sparse sampling: Spatial design for monitoring stream networks

    EPA Science Inventory

    Spatial designs for monitoring stream networks, especially ephemeral systems, are typically non-standard, ‘sparse’ and can be very complex, reflecting the complexity of the ecosystem being monitored, the scale of the population, and the competing multiple monitoring objectives. ...

  1. Atmospheric carbon diooxide mixing ratios from the NOAA Climate Monitoring and Diagnostics Laboratory cooperative flask sampling network, 1967-1993

    SciTech Connect

    Conway, T.J.; Tans, P.P.; BBoden, T.A.

    1996-02-01

    This data report documents monthly atmospheric CO{sub 2} mixing ratios and measurements obtained by analyzing individual flask air samples for the NOAA/CMDL global cooperative flask sampling network. Measurements include land-based sampling sites and shipboard measurements covering 14 latitude bands in the Pacific Ocean and South China Sea. Analysis of the NOAA/CMDL flask CO{sub 2} database shows a long-term increase in atmospheric CO{sub 2} mixing ratios since the late 1960s. This report describes how the samples are collected and analyzed and how the data are processed, defines limitations, and restrictions of the data, describes the contents and format of the data files, and provides tabular listings of the monthly carbon dioxide records.

  2. Data Quality Objectives for Regulatory Requirements for Hazardous and Radioactive Air Emissions Sampling and Analysis

    SciTech Connect

    MULKEY, C.H.

    1999-07-06

    This document describes the results of the data quality objective (DQO) process undertaken to define data needs for state and federal requirements associated with toxic, hazardous, and/or radiological air emissions under the jurisdiction of the River Protection Project (RPP). Hereafter, this document is referred to as the Air DQO. The primary drivers for characterization under this DQO are the regulatory requirements pursuant to Washington State regulations, that may require sampling and analysis. The federal regulations concerning air emissions are incorporated into the Washington State regulations. Data needs exist for nonradioactive and radioactive waste constituents and characteristics as identified through the DQO process described in this document. The purpose is to identify current data needs for complying with regulatory drivers for the measurement of air emissions from RPP facilities in support of air permitting. These drivers include best management practices; similar analyses may have more than one regulatory driver. This document should not be used for determining overall compliance with regulations because the regulations are in constant change, and this document may not reflect the latest regulatory requirements. Regulatory requirements are also expected to change as various permits are issued. Data needs require samples for both radionuclides and nonradionuclide analytes of air emissions from tanks and stored waste containers. The collection of data is to support environmental permitting and compliance, not for health and safety issues. This document does not address health or safety regulations or requirements (those of the Occupational Safety and Health Administration or the National Institute of Occupational Safety and Health) or continuous emission monitoring systems. This DQO is applicable to all equipment, facilities, and operations under the jurisdiction of RPP that emit or have the potential to emit regulated air pollutants.

  3. High-throughput liquid-absorption air-sampling apparatus and methods

    DOEpatents

    Zaromb, Solomon

    2000-01-01

    A portable high-throughput liquid-absorption air sampler [PHTLAAS] has an asymmetric air inlet through which air is drawn upward by a small and light-weight centrifugal fan driven by a direct current motor that can be powered by a battery. The air inlet is so configured as to impart both rotational and downward components of motion to the sampled air near said inlet. The PHTLAAS comprises a glass tube of relatively small size through which air passes at a high rate in a swirling, highly turbulent motion, which facilitates rapid transfer of vapors and particulates to a liquid film covering the inner walls of the tube. The pressure drop through the glass tube is <10 cm of water, usually <5 cm of water. The sampler's collection efficiency is usually >20% for vapors or airborne particulates in the 2-3.mu. range and >50% for particles larger than 4.mu.. In conjunction with various analyzers, the PHTLAAS can serve to monitor a variety of hazardous or illicit airborne substances, such as lead-containing particulates, tritiated water vapor, biological aerosols, or traces of concealed drugs or explosives.

  4. High-Density, High-Resolution, Low-Cost Air Quality Sensor Networks for Urban Air Monitoring

    NASA Astrophysics Data System (ADS)

    Mead, M. I.; Popoola, O. A.; Stewart, G.; Bright, V.; Kaye, P.; Saffell, J.

    2012-12-01

    Monitoring air quality in highly granular environments such as urban areas which are spatially heterogeneous with variable emission sources, measurements need to be made at appropriate spatial and temporal scales. Current routine air quality monitoring networks generally are either composed of sparse expensive installations (incorporating e.g. chemiluminescence instruments) or higher density low time resolution systems (e.g. NO2 diffusion tubes). Either approach may not accurately capture important effects such as pollutant "hot spots" or adequately capture spatial (or temporal) variability. As a result, analysis based on data from traditional low spatial resolution networks, such as personal exposure, may be inaccurate. In this paper we present details of a sophisticated, low-cost, multi species (gas phase, speciated PM, meteorology) air quality measurement network methodology incorporating GPS and GPRS which has been developed for high resolution air quality measurements in urban areas. Sensor networks developed in the Centre for Atmospheric Science (University of Cambridge) incorporated electrochemical gas sensors configured for use in urban air quality studies operating at parts-per-billion (ppb) levels. It has been demonstrated that these sensors can be used to measure key air quality gases such as CO, NO and NO2 at the low ppb mixing ratios present in the urban environment (estimated detection limits <4ppb for CO and NO and <1ppb for NO2. Mead et al (submitted Aug., 2012)). Based on this work, a state of the art multi species instrument package for deployment in scalable sensor networks has been developed which has general applicability. This is currently being employed as part of a major 3 year UK program at London Heathrow airport (the Sensor Networks for Air Quality (SNAQ) Heathrow project). The main project outcome is the creation of a calibrated, high spatial and temporal resolution data set for O3, NO, NO2, SO2, CO, CO2, VOCstotal, size-speciated PM

  5. Results of Self-Absorption Study on the Versapor 3000 Filters for Radioactive Particulate Air Sampling

    SciTech Connect

    Barnett, J. Matthew

    2008-08-22

    Since the mid-1980s the Pacific Northwest National Laboratory (PNNL) has used a value of 0.85 as a correction factor for the self absorption of activity of particulate radioactive air samples. More recently, an effort was made to evaluate the current particulate radioactive air sample filters (Versapor® 3000) used at PNNL for self absorption effects. There were two methods used in the study, 1) to compare the radioactivity concentration by direct gas-flow proportional counting of the filter to the results obtained after acid digestion of the filter and counting again by gas-flow proportional detection and 2) to evaluate sample filters by high resolution visual/infrared microscopy to determine the depth of material loading on or in the filter fiber material. Sixty samples were selected from the archive for acid digestion in the first method and about 30 samples were selected for high resolution visual/infrared microscopy. Mass loading effects were also considered. From the sample filter analysis, large error is associated with the average self absorption factor, however, when the data is compared directly one-to-one, statistically, there appears to be good correlation between the two analytical methods. The mass loading of filters evaluated was <0.2 mg cm-2 and was also compared against other published results. The microscopy analysis shows the sample material remains on the top of the filter paper and does not imbed into the filter media. Results of the microscopy evaluation lead to the conclusion that there is not a mechanism for significant self absorption. The overall conclusion is that self-absorption is not a significant factor in the analysis of filters used at PNNL for radioactive air stack sampling of radionuclide particulates and that an applied correction factor is conservative in determining overall sample activity. A new self absorption factor of 1.0 is recommended.

  6. Chemical reactivities of ambient air samples in three Southern California communities

    PubMed Central

    Eiguren-Fernandez, Arantza; Di Stefano, Emma; Schmitz, Debra A.; Guarieiro, Aline Lefol Nani; Salinas, Erika M.; Nasser, Elina; Froines, John R.; Cho, Arthur K.

    2015-01-01

    The potential adverse health effects of PM2.5 and vapor samples from three communities that neighbor railyards, Commerce (CM), Long Beach (LB), and San Bernardino (SB), were assessed by determination of chemical reactivities attributed to the induction of oxidative stress by air pollutants. The assays used were dithiothreitol (DTT) and dihydrobenzoic acid (DHBA) based procedures for prooxidant content and a glyceraldehyde-3-phosphate dehydrogenase (GAPDH) assay for electrophiles. Prooxidants and electrophiles have been proposed as the reactive chemical species responsible for the induction of oxidative stress by air pollution mixtures. The PM2.5 samples from CM and LB sites showed seasonal differences in reactivities with higher levels in the winter whereas the SB sample differences were reversed. The reactivities in the vapor samples were all very similar, except for the summer SB samples, which contained higher levels of both prooxidants and electrophiles. The results suggest the observed reactivities reflect general geographical differences rather than direct effects of the railyards. Distributional differences in reactivities were also observed with PM2.5 fractions containing most of the prooxidants (74–81%) and the vapor phase most of the electrophiles (82–96%). The high levels of the vapor phase electrophiles and their potential for adverse biological effects point out the importance of the vapor phase in assessing the potential health effects of ambient air. PMID:25947123

  7. Mathematical estimation of the level of microbial contamination on spacecraft surfaces by volumetric air sampling

    NASA Technical Reports Server (NTRS)

    Oxborrow, G. S.; Roark, A. L.; Fields, N. D.; Puleo, J. R.

    1974-01-01

    Microbiological sampling methods presently used for enumeration of microorganisms on spacecraft surfaces require contact with easily damaged components. Estimation of viable particles on surfaces using air sampling methods in conjunction with a mathematical model would be desirable. Parameters necessary for the mathematical model are the effect of angled surfaces on viable particle collection and the number of viable cells per viable particle. Deposition of viable particles on angled surfaces closely followed a cosine function, and the number of viable cells per viable particle was consistent with a Poisson distribution. Other parameters considered by the mathematical model included deposition rate and fractional removal per unit time. A close nonlinear correlation between volumetric air sampling and airborne fallout on surfaces was established with all fallout data points falling within the 95% confidence limits as determined by the mathematical model.

  8. A survey of results for passive air and water sampling via semipermeable membrane devices

    SciTech Connect

    Prest, H.F.; Jacobson, L.; Hodgins, M.; Huckins, J.N.; Petty, J.D.; Richardson, B.; Wilson, M.; Martin, M.

    1994-12-31

    Passive sampling techniques have progressed and are providing new possibilities for measuring trace contaminants in environmental compartments. One such device, the semipermeable membrane device (SPMD) developed by Huckins, et al in Columbia, MO. is especially promising. The authors present an overview of results for sampling in air and water with semipermeable membrane devices (SPMDS) for organochlorines and polynuclear aromatic hydrocarbons (PAHs) and comment on possible future applications and potential. Differences in organohalogen profiles for SPMDs and green-lipped mussels deployed along transacts of Corio Bay, Australia show marked differences in sequestering ``windows``. An illustration of the application of SPMDs to the measurement of the half-life of chemicals is presented using PAH data from SPMD deployments in an irrigation canal in New Mexico. Results for simultaneous sampling of water and coastal air in Northern California illustrate the promise of SPMDs as global monitors.

  9. A Survey of Wireless Sensor Network Based Air Pollution Monitoring Systems

    PubMed Central

    Yi, Wei Ying; Lo, Kin Ming; Mak, Terrence; Leung, Kwong Sak; Leung, Yee; Meng, Mei Ling

    2015-01-01

    The air quality in urban areas is a major concern in modern cities due to significant impacts of air pollution on public health, global environment, and worldwide economy. Recent studies reveal the importance of micro-level pollution information, including human personal exposure and acute exposure to air pollutants. A real-time system with high spatio-temporal resolution is essential because of the limited data availability and non-scalability of conventional air pollution monitoring systems. Currently, researchers focus on the concept of The Next Generation Air Pollution Monitoring System (TNGAPMS) and have achieved significant breakthroughs by utilizing the advance sensing technologies, MicroElectroMechanical Systems (MEMS) and Wireless Sensor Network (WSN). However, there exist potential problems of these newly proposed systems, namely the lack of 3D data acquisition ability and the flexibility of the sensor network. In this paper, we classify the existing works into three categories as Static Sensor Network (SSN), Community Sensor Network (CSN) and Vehicle Sensor Network (VSN) based on the carriers of the sensors. Comprehensive reviews and comparisons among these three types of sensor networks were also performed. Last but not least, we discuss the limitations of the existing works and conclude the objectives that we want to achieve in future systems. PMID:26703598

  10. A Survey of Wireless Sensor Network Based Air Pollution Monitoring Systems.

    PubMed

    Yi, Wei Ying; Lo, Kin Ming; Mak, Terrence; Leung, Kwong Sak; Leung, Yee; Meng, Mei Ling

    2015-12-12

    The air quality in urban areas is a major concern in modern cities due to significant impacts of air pollution on public health, global environment, and worldwide economy. Recent studies reveal the importance of micro-level pollution information, including human personal exposure and acute exposure to air pollutants. A real-time system with high spatio-temporal resolution is essential because of the limited data availability and non-scalability of conventional air pollution monitoring systems. Currently, researchers focus on the concept of The Next Generation Air Pollution Monitoring System (TNGAPMS) and have achieved significant breakthroughs by utilizing the advance sensing technologies, MicroElectroMechanical Systems (MEMS) and Wireless Sensor Network (WSN). However, there exist potential problems of these newly proposed systems, namely the lack of 3D data acquisition ability and the flexibility of the sensor network. In this paper, we classify the existing works into three categories as Static Sensor Network (SSN), Community Sensor Network (CSN) and Vehicle Sensor Network (VSN) based on the carriers of the sensors. Comprehensive reviews and comparisons among these three types of sensor networks were also performed. Last but not least, we discuss the limitations of the existing works and conclude the objectives that we want to achieve in future systems.

  11. A stringent comparison of sampling and analysis methods for VOCs in ambient air

    SciTech Connect

    Daughtrey, E.H. Jr.; Oliver, K.D.; Adams, J.R.; Kronmiller, K.G.; Lonneman, W.A.; McClenny, W.A.; Colon, M.

    1999-07-01

    A carefully designed study was conducted during the summer of 1998 to simultaneously collect samples of ambient air by canisters and compare the analysis results to direct sorbent preconcentration results taken at the time of sample collection. A total of 32 1-h sample sets were taken, each composed of a real-time sample analyzed by an autoGC/MS XonTech 930/Varian Saturn 2000 system, and SUMMA and Silco canisters. Hourly total non-methane organic carbon (TNMOC), ozone, and meteorological measurements were also made. Each of the canisters was analyzed on the autoGC/MS system for a target list of 108 VOCs and on a manual cryosampling GC/FID system. Comparisons are made between the collection and analysis methods. Because of the low sample loading (150--250 ppbC TNMOC), these comparisons are a stringent test of sample collection and analysis capabilities.

  12. Whole Air Sampling During NASA's March-April 1999 Pacific Exploratory Expedition (PEM-Tropics B)

    NASA Technical Reports Server (NTRS)

    Blake, Donald R.

    2001-01-01

    University of California, Irvine (UCI) collected more than 4500 samples whole air samples collected over the remote Pacific Ocean during NASA's Global Tropospheric Experiment (GTE) Pacific Exploratory Mission-Tropics B (PEM-Tropics B) in March and early April 1999. Approximately 140 samples during a typical 8-hour DC-8 flight, and 120 canisters for each 8-hour flight aboard the P-3B. These samples were obtained roughly every 3-7 min during horizontal flight legs and 1-3 min during vertical legs. The filled canisters were analyzed in the laboratory at UCI within ten days of collection. The mixing ratios of 58 trace gases comprising hydrocarbons, halocarbons, alkyl nitrates and DMS were reported (and archived) for each sample. Two identical analytical systems sharing the same standards were operated simultaneously around the clock to improve canister turn-around time and to keep our measurement precision optimal. This report presents a summary of the results for sample collected.

  13. Monitoring airborne fungal spores in an experimental indoor environment to evaluate sampling methods and the effects of human activity on air sampling.

    PubMed Central

    Buttner, M P; Stetzenbach, L D

    1993-01-01

    Aerobiological monitoring was conducted in an experimental room to aid in the development of standardized sampling protocols for airborne microorganisms in the indoor environment. The objectives of this research were to evaluate the relative efficiencies of selected sampling methods for the retrieval of airborne fungal spores and to determine the effect of human activity on air sampling. Dry aerosols containing known concentrations of Penicillium chrysogenum spores were generated, and air samples were taken by using Andersen six-stage, Surface Air System, Burkard, and depositional samplers. The Andersen and Burkard samplers retrieved the highest numbers of spores compared with the measurement standard, an aerodynamic particle sizer located inside the room. Data from paired samplers demonstrated that the Andersen sampler had the highest levels of sensitivity and repeatability. With a carpet as the source of P. chrysogenum spores, the effects of human activity (walking or vacuuming near the sampling site) on air sampling were also examined. Air samples were taken under undisturbed conditions and after human activity in the room. Human activity resulted in retrieval of significantly higher concentrations of airborne spores. Surface sampling of the carpet revealed moderate to heavy contamination despite relatively low airborne counts. Therefore, in certain situations, air sampling without concomitant surface sampling may not adequately reflect the level of microbial contamination in indoor environments. PMID:8439150

  14. Volatile organic components of air samples collected from Vertical Launch Missile capsules. Summary report

    SciTech Connect

    Tappan, D.V.; Knight, D.R.; Heyder, E.; Weathersby, P.K.

    1988-09-27

    Gas chromatographic/mass spectroscopic analyses are presented for the volatile organic components found in air samples collected from the inboard vents from Vertical Launch System (VLS) missile capsules aboard a 688 class submarine. Similar analyses were also conducted for a sample of the ship's high pressure air used to fill the missile tubes. A wide variety of organics was detected in the air from the missile capsules; and while no unique components have yet been identified, a significant contribution has been shown to be made by pressure-ventilation of the VLS capsules into the submarine atmosphere which is already heavily laden with volatile organic compounds. The most apparent conclusion from these preliminary analyses is that the mixtures of organic components in the air within VLS missile capsules vary greatly from capsule to capsule (and probably from time to time). Many such samples need to be investigated to provide sufficient information to judge the seriousness of the possibility of venting toxic components into the submarine atmosphere during the maintenance or firing of VLS missiles.

  15. Prediction of Indoor Air Exposure from Outdoor Air Quality Using an Artificial Neural Network Model for Inner City Commercial Buildings.

    PubMed

    Challoner, Avril; Pilla, Francesco; Gill, Laurence

    2015-12-01

    NO₂ and particulate matter are the air pollutants of most concern in Ireland, with possible links to the higher respiratory and cardiovascular mortality and morbidity rates found in the country compared to the rest of Europe. Currently, air quality limits in Europe only cover outdoor environments yet the quality of indoor air is an essential determinant of a person's well-being, especially since the average person spends more than 90% of their time indoors. The modelling conducted in this research aims to provide a framework for epidemiological studies by the use of publically available data from fixed outdoor monitoring stations to predict indoor air quality more accurately. Predictions are made using two modelling techniques, the Personal-exposure Activity Location Model (PALM), to predict outdoor air quality at a particular building, and Artificial Neural Networks, to model the indoor/outdoor relationship of the building. This joint approach has been used to predict indoor air concentrations for three inner city commercial buildings in Dublin, where parallel indoor and outdoor diurnal monitoring had been carried out on site. This modelling methodology has been shown to provide reasonable predictions of average NO₂ indoor air quality compared to the monitored data, but did not perform well in the prediction of indoor PM2.5 concentrations. Hence, this approach could be used to determine NO₂ exposures more rigorously of those who work and/or live in the city centre, which can then be linked to potential health impacts.

  16. Prediction of Indoor Air Exposure from Outdoor Air Quality Using an Artificial Neural Network Model for Inner City Commercial Buildings

    PubMed Central

    Challoner, Avril; Pilla, Francesco; Gill, Laurence

    2015-01-01

    NO2 and particulate matter are the air pollutants of most concern in Ireland, with possible links to the higher respiratory and cardiovascular mortality and morbidity rates found in the country compared to the rest of Europe. Currently, air quality limits in Europe only cover outdoor environments yet the quality of indoor air is an essential determinant of a person’s well-being, especially since the average person spends more than 90% of their time indoors. The modelling conducted in this research aims to provide a framework for epidemiological studies by the use of publically available data from fixed outdoor monitoring stations to predict indoor air quality more accurately. Predictions are made using two modelling techniques, the Personal-exposure Activity Location Model (PALM), to predict outdoor air quality at a particular building, and Artificial Neural Networks, to model the indoor/outdoor relationship of the building. This joint approach has been used to predict indoor air concentrations for three inner city commercial buildings in Dublin, where parallel indoor and outdoor diurnal monitoring had been carried out on site. This modelling methodology has been shown to provide reasonable predictions of average NO2 indoor air quality compared to the monitored data, but did not perform well in the prediction of indoor PM2.5 concentrations. Hence, this approach could be used to determine NO2 exposures more rigorously of those who work and/or live in the city centre, which can then be linked to potential health impacts. PMID:26633448

  17. Soyuz 22 Return Samples: Assessment of Air Quality Aboard the International Space Station

    NASA Technical Reports Server (NTRS)

    Jams, John T.

    2010-01-01

    Three mini-grab sample containers (m-GSCs) were returned aboard Soyuz 22 because of concerns that new air pollutants were present in the air and these were getting into the water recovery system. The Total Organic Carbon Analyzer had been giving increasing readings of total organic carbon (TOC) in the potable water, and it was postulated that an increased load into the system was responsible. The toxicological assessment of 3 m-GSCs from the ISS is shown in Table 1. The recoveries of the 3 standards (as listed above) from the GSCs averaged 103, 95 and 76%, respectively. Recovery from formaldehyde control badges were 90 and 91%.

  18. Quantitative Passive Diffusive Sampling for Assessing Soil Vapor Intrusion to Indoor Air

    DTIC Science & Technology

    2012-03-28

    4/11/2012 1 Quantitative Passive Diffusive Sampling for Assessing Soil Vapor Intrusion to Indoor Air Todd McAlary and Hester Groenevelt, Geosyntec... Intrusion to Indoor Air 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK...10-6 risk (ppb) Vapour pressure (atm) Water solubility (g/l) 1,1,1-Trichloroethane 110 400 0.16 1.33 1,2,4-Trimethylbenzene

  19. Understanding the effects of administrative boundary in sampling spatially embedded networks

    NASA Astrophysics Data System (ADS)

    Chi, Guanghua; Liu, Yu; Shi, Li; Gao, Yong

    2017-01-01

    When analyzing spatially embedded networks, networks consisting of nodes and connections within an administrative boundary are commonly analyzed directly without considering possible errors or biases due to lost connections to nodes outside the network. However, connections exist not only within administrative boundaries but also to nodes outside of the boundaries. This study empirically analyzed the geographical boundary problem using a mobile communication network constructed based on mobile phone data collected in Heilongjiang province, China. We find that although many connections outside of the administrative boundary are lost, sampled networks based on administrative boundaries perform relatively well in terms of degree and clustering coefficient. We find that the mechanisms behind the reliability of these sampled networks include the effects of distance decay and cohesion strength in administrative regions on spatially embedded networks.

  20. Use of Respondent Driven Sampling (RDS) Generates a Very Diverse Sample of Men Who Have Sex with Men (MSM) in Buenos Aires, Argentina

    PubMed Central

    Carballo-Diéguez, Alex; Balan, Ivan; Marone, Rubén; Pando, María A.; Dolezal, Curtis; Barreda, Victoria; Leu, Cheng-Shiun; Ávila, María Mercedes

    2011-01-01

    Background Prior research focusing on men who have sex with men (MSM) conducted in Buenos Aires, Argentina, used convenience samples that included mainly gay identified men. To increase MSM sample representativeness, we used Respondent Driven Sampling (RDS) for the first time in Argentina. Using RDS, under certain specified conditions, the observed estimates for the percentage of the population with a specific trait are asymptotically unbiased. We describe, the diversity of the recruited sample, from the point of view of sexual orientation, and contrast the different subgroups in terms of their HIV sexual risk behavior. Methodology 500 MSM were recruited using RDS. Behavioral data were collected through face-to-face interviews and Web-based CASI. Conclusion In contrast with prior studies, RDS generated a very diverse sample of MSM from a sexual identity perspective. Only 24.5% of participants identified as gay; 36.2% identified as bisexual, 21.9% as heterosexual, and 17.4% were grouped as “other.” Gay and non-gay identified MSM differed significantly in their sexual behavior, the former having higher numbers of partners, more frequent sexual contacts and less frequency of condom use. One third of the men (gay, 3%; bisexual, 34%, heterosexual, 51%; other, 49%) reported having had sex with men, women and transvestites in the two months prior to the interview. This population requires further study and, potentially, HIV prevention strategies tailored to such diversity of partnerships. Our results highlight the potential effectiveness of using RDS to reach non-gay identified MSM. They also present lessons learned in the implementation of RDS to recruit MSM concerning both the importance and limitations of formative work, the need to tailor incentives to circumstances of the less affluent potential participants, the need to prevent masking, and the challenge of assessing network size. PMID:22102896

  1. Indoor-Air Microbiome in an Urban Subway Network: Diversity and Dynamics

    PubMed Central

    Leung, Marcus H. Y.; Wilkins, David; Li, Ellen K. T.; Kong, Fred K. F.

    2014-01-01

    Subway systems are indispensable for urban societies, but microbiological characteristics of subway aerosols are relatively unknown. Previous studies investigating microbial compositions in subways employed methodologies that underestimated the diversity of microbial exposure for commuters, with little focus on factors governing subway air microbiology, which may have public health implications. Here, a culture-independent approach unraveling the bacterial diversity within the urban subway network in Hong Kong is presented. Aerosol samples from multiple subway lines and outdoor locations were collected. Targeting the 16S rRNA gene V4 region, extensive taxonomic diversity was found, with the most common bacterial genera in the subway environment among those associated with skin. Overall, subway lines harbored different phylogenetic communities based on α- and β-diversity comparisons, and closer inspection suggests that each community within a line is dependent on architectural characteristics, nearby outdoor microbiomes, and connectedness with other lines. Microbial diversities and assemblages also varied depending on the day sampled, as well as the time of day, and changes in microbial communities between peak and nonpeak commuting hours were attributed largely to increases in skin-associated genera in peak samples. Microbial diversities within the subway were influenced by temperature and relative humidity, while carbon dioxide levels showed a positive correlation with abundances of commuter-associated genera. This Hong Kong data set and communities from previous studies conducted in the United States formed distinct community clusters, indicating that additional work is required to unravel the mechanisms that shape subway microbiomes around the globe. PMID:25172855

  2. A comparison of network sampling designs for a hidden population of drug users: Random walk vs. respondent-driven sampling.

    PubMed

    Bell, David C; Erbaugh, Elizabeth B; Serrano, Tabitha; Dayton-Shotts, Cheryl A; Montoya, Isaac D

    2017-02-01

    Both random walk and respondent-driven sampling (RDS) exploit social networks and may reduce biases introduced by earlier methods for sampling from hidden populations. Although RDS has become much more widely used by social researchers than random walk (RW), there has been little discussion of the tradeoffs in choosing RDS over RW. This paper compares experiences of implementing RW and RDS to recruit drug users to a network-based study in Houston, Texas. Both recruitment methods were implemented over comparable periods of time, with the same population, by the same research staff. RDS methods recruited more participants with less strain on staff. However, participants recruited through RW were more forthcoming than RDS participants in helping to recruit members of their social networks. Findings indicate that, dependent upon study goals, researchers' choice of design may influence participant recruitment, participant commitment, and impact on staff, factors that may in turn affect overall study success.

  3. Development of a unique multi-contaminant air sampling device for a childhood asthma cohort in an agricultural environment†

    PubMed Central

    Fitzpatrick, Cole F.; Loftus, Christine T.; Yost, Michael G.; Tchong-French, Maria; Karr, Catherine J.

    2016-01-01

    This research describes the design, deployment, performance, and acceptability of a novel outdoor active air sampler to provide simultaneous measurements of multiple contaminants at timed intervals for the Aggravating Factors of Asthma in Rural Environment (AFARE) study—a longitudinal cohort of 50 children in Yakima Valley, Washington. The sampler was constructed of multiple sampling media connected to individual critical orifices and a rotary vane vacuum pump. It was connected to a timed control valve system to collect 24 hours samples every six days over 18 months. We describe a spatially representative approach with both quantitative and qualitative location criteria to deploy a network of 14 devices at participant residences in a rural region (20 × 60 km). Overall the sampler performed well, as the concurrent mean sample flow rates were within or above the ranges of recommended sampling rates for each exposure metric of interest. Acceptability was high among the study population of Hispanic farmworker participant households. The sampler design may prove useful for future urban and rural community-based studies with aims at collecting multiple contaminant data during specific time periods. PMID:23896655

  4. Determination of air-loop volume and radon partition coefficient for measuring radon in water sample.

    PubMed

    Lee, Kil Yong; Burnett, William C

    A simple method for the direct determination of the air-loop volume in a RAD7 system as well as the radon partition coefficient was developed allowing for an accurate measurement of the radon activity in any type of water. The air-loop volume may be measured directly using an external radon source and an empty bottle with a precisely measured volume. The partition coefficient and activity of radon in the water sample may then be determined via the RAD7 using the determined air-loop volume. Activity ratios instead of absolute activities were used to measure the air-loop volume and the radon partition coefficient. In order to verify this approach, we measured the radon partition coefficient in deionized water in the temperature range of 10-30 °C and compared the values to those calculated from the well-known Weigel equation. The results were within 5 % variance throughout the temperature range. We also applied the approach for measurement of the radon partition coefficient in synthetic saline water (0-75 ppt salinity) as well as tap water. The radon activity of the tap water sample was determined by this method as well as the standard RAD-H2O and BigBottle RAD-H2O. The results have shown good agreement between this method and the standard methods.

  5. Direct high-resolution alpha spectrometry from nuclear fuel particles in an outdoor air sample.

    PubMed

    Pöllänen, R; Siiskonen, T

    2008-01-01

    The potential use of direct high-resolution alpha spectrometry to identify the presence of transactinium elements in air samples is illustrated in the case when alpha-particle-emitting radionuclides are incorporated in nuclear fuel particles. Alpha particle energy spectra are generated through Monte Carlo simulations assuming a nuclide composition similar to RBMK (Chernobyl) nuclear fuel. The major alpha-particle-emitting radionuclides, in terms of activity, are 242Cm, 239Pu and 240Pu. The characteristics of the alpha peaks are determined by fuel particle properties as well as the type of the air filter. It is shown that direct alpha spectrometry can be readily applied to membrane filter samples containing nuclear fuel particles when rapid nuclide identification is of relevance. However, the development of a novel spectrum analysis code is a prerequisite for unfolding complex alpha spectra.

  6. Networking of ACSC (Air Command and Staff College) Microcomputers.

    DTIC Science & Technology

    1988-01-01

    Digital Equipment Corporation , Hewlett Packard, Xerox Corporation , Ungermann-Bass Inc., and 3Com Corporation . In a recent survey, it was determined that...and - .i Intel corporations . Uses bus topology with coaxial 4’ cable. expandability -- Feature of a network allowing the network to be expanded with... communicatins channels are interconnected. peripherals -- Computer components such as terminals, printers, copiers, disk units or tape drives. personal

  7. Stability in alkaline aqueous electrolyte of air electrode protected with fluorinated interpenetrating polymer network membrane

    NASA Astrophysics Data System (ADS)

    Bertolotti, Bruno; Messaoudi, Houssam; Chikh, Linda; Vancaeyzeele, Cédric; Alfonsi, Séverine; Fichet, Odile

    2015-01-01

    We developed original anion exchange membranes to protect air electrodes operating in aqueous lithium-air battery configuration, i.e. supplied with atmospheric air and in concentrated aqueous lithium hydroxide. These protective membranes have an interpenetrating polymer network (IPN) architecture combining a hydrogenated cationic polyelectrolyte network based on poly(epichlorohydrin) (PECH) and a fluorinated neutral network based on perfluoropolyether (Fluorolink® MD700). Two phases, each one rich in one of the polymer, are co-continuous in the materials. This morphology allows combining their properties according to the weight proportions of each polymer. Thus, PECH/Fluorolink IPNs show ionic conductivity varying from 1 to 2 mS cm-1, water uptake from 30 to 90 wt.% and anionic transport number from 0.65 to 0.80 when the PECH proportion varies from 40 to 90 wt.%. These membranes have been systematically assembled on air electrodes. Air electrode protected with PECH/Fluorolink 70/30 IPN shows outstanding stability higher than 1000 h, i.e. a 20-fold increase in the lifetime of the non-modified electrode. This efficient membrane/air electrode assembly is promising for development of alkaline electrolyte based storage or production energy systems, such as metal air batteries or alkaline fuel cells.

  8. Air Sampling of Polychlorinated Dibenzodioxins, Polychlorinated Dibenzofurans, and Polychlorinated Biphenyls Arnold AFS, Tennessee.

    DTIC Science & Technology

    1987-01-01

    DIBENZOFURANS, AND POLYCHLORINATED BIPHENYLS ARNOLD AFS TN ISAAC ATKINS, JR., CAPTAIN, USAF, BSC January 1987 D I ~ELECTE FINAL REPORT 0Wfl D LU...NO 11. TITLE (Include Security ClassificatiOtl) Air Sampling of Polychlorinated Dibenzodioxins, Polychlorinated Dibenzofurans, and Polychlorinated ... Biphenyls at Arnold AFS TN (U) 12. PERSONAL AUTHOR(S) Captaiq Isaac Atkins, Jr. 13a. TYP OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Month

  9. STS-65 Commander Cabana and PLC Hieb take air sample at IML-2 Rack 7 NIZEMI

    NASA Technical Reports Server (NTRS)

    1994-01-01

    STS-65 Commander Robert D. Cabana (right) and Payload Commander (PLC) Richard J. Hieb take an air sample inside the International Microgravity Laboratory 2 (IML-2) spacelab science module. The two crewmembers are in front of Rack 7 which contains the large isothermal furnace (LIF) and slow rotating centrifuge microscope (NIZEMI). The photo was among the first group released by NASA following the two-week IML-2 mission aboard the Space Shuttle Columbia, Orbiter Vehicle (OV) 102.

  10. Measurement of the Tracer Gradient and Sampling System Bias of the Hot Fuel Examination Facility Stack Air Monitoring System

    SciTech Connect

    Glissmeyer, John A.; Flaherty, Julia E.

    2011-07-20

    This report describes tracer gas uniformity and bias measurements made in the exhaust air discharge of the Hot Fuel Examination Facility at Idaho National Laboratory. The measurements were a follow-up on earlier measurements which indicated a lack of mixing of the two ventilation streams being discharged via a common stack. The lack of mixing is detrimental to the accuracy of air emission measurements. The lack of mixing was confirmed in these new measurements. The air sampling probe was found to be out of alignment and that was corrected. The suspected sampling bias in the air sample stream was disproved.

  11. Isotopic air sampling in a tallgrass prairie to partition net ecosystem CO2 exchange

    NASA Astrophysics Data System (ADS)

    Lai, Chun-Ta; Schauer, Andrew J.; Owensby, Clenton; Ham, Jay M.; Ehleringer, James R.

    2003-09-01

    Stable isotope ratios of various ecosystem components and net ecosystem exchange (NEE) CO2 fluxes were measured in a C3-C4 mixture tallgrass prairie near Manhattan, Kansas. The July 2002 study period was chosen because of contrasting soil moisture contents, which allowed us to address the effects of drought on photosynthetic CO2 uptake and isotopic discrimination. Significantly higher NEE fluxes were observed for both daytime uptake and nighttime respiration during well-watered conditions when compared to a drought period. Given these differences, we investigated two carbon-flux partitioning questions: (1) What proportions of NEE were contributed by C3 versus C4 species? (2) What proportions of NEE fluxes resulted from canopy assimilation versus ecosystem respiration? To evaluate these questions, air samples were collected every 2 hours during daytime for 3 consecutive days at the same height as the eddy covariance system. These air samples were analyzed for both carbon isotope ratios and CO2 concentrations to establish an empirical relationship for isoflux calculations. An automated air sampling system was used to collect nighttime air samples to estimate the carbon isotope ratios of ecosystem respiration (δR) at weekly intervals for the entire growing season. Models of C3 and C4 photosynthesis were employed to estimate bulk canopy intercellular CO2 concentration in order to calculate photosynthetic discrimination against 13C. Our isotope/NEE results showed that for this grassland, C4 vegetation contributed ˜80% of the NEE fluxes during the drought period and later ˜100% of the NEE fluxes in response to an impulse of intense precipitation. For the entire growing season, the C4 contribution ranged from ˜68% early in the spring to nearly 100% in the late summer. Using an isotopic approach, the calculated partitioned respiratory fluxes were slightly greater than chamber-measured estimates during midday under well-watered conditions. In addition, time series

  12. Microbial Air and Surface Monitoring Results from International Space Station Samples

    NASA Technical Reports Server (NTRS)

    Ott, C. Mark; Bruce, Rebekah J.; Castro, Victoria A.; Novikova, Natalia D.; Pierson, D. L.

    2005-01-01

    Over the course of long-duration spaceflight, spacecraft develop a microbial ecology that directly interacts with the crew of the vehicle. While most microorganisms are harmless or beneficial to the inhabitants of the vehicle, the presence of medically significant organisms appearing in this semi-closed environment could adversely affect crew health and performance. The risk of exposure of the crew to medically significant organisms during a mission is estimated using information gathered during nominal and contingency environmental monitoring. Analysis of the air and surface microbiota in the habitable compartments of the International Space Station (ISS) over the last four years indicate a high presence of Staphylococcus species reflecting the human inhabitants of the vehicle. Generally, air and surface microbial concentrations are below system design specifications, suggesting a lower risk of contact infection or biodegradation. An evaluation of sample frequency indicates a decrease in the identification of new species, suggesting a lower potential for unknown microorganisms to be identified. However, the opportunistic pathogen, Staphylococcus aureus, has been identified in 3 of the last 5 air samples and 5 of the last 9 surface samples. In addition, 47% of the coagulase negative Staphylococcus species that were isolated from the crew, ISS, and its hardware were found to be methicillin resistance. In combination, these observations suggest the potential of methicillin resistant infectious agents over time.

  13. Technical assessment of workplace air sampling requirements at tank farm facilities. Revision 1

    SciTech Connect

    Olsen, P.A.

    1994-09-21

    WHC-CM-1-6 is the primary guidance for radiological control at Westinghouse Hanford Company (WHC). It was written to implement DOE N 5480.6 ``US Department of Energy Radiological Control Manual`` as it applies to programs at Hanford which are now overseen by WHC. As such, it complies with Title 10, Part 835 of the Code of Federal Regulations. In addition to WHC-CM-1-6, there is HSRCM-1, the ``Hanford Site Radiological Control Manual`` and several Department of Energy (DOE) Orders, national consensus standards, and reports that provide criteria, standards, and requirements for workplace air sampling programs. This document provides a summary of these, as they apply to WHC facility workplace air sampling programs. This document also provides an evaluation of the compliance of Tank Farms` workplace air sampling program to the criteria, standards, and requirements and documents compliance with the requirements where appropriate. Where necessary, it also indicates changes needed to bring specific locations into compliance.

  14. Organic toxicants in air and precipitation samples from the Lake Michigan area

    SciTech Connect

    Harlin, K.S.; Sweet, C.W.; Gatz, D.F.

    1995-12-31

    Measurements of PCBs, organochlorine insecticides, PAHs, and atrazine were made in air and precipitation samples collected at regionally-representative locations near Lake Michigan from 1992-1995. The purpose of these measurements was to provide information needed to estimate the atmospheric deposition of organic toxicants to Lake Michigan. Twenty-four hour samples of airborne particles and vapor were collected at 12-day intervals on quartz fiber filters and XAD-2 resin vapor traps using modified high volume sampleers. Twenty-eight day precipitation samples were collected using wet-only samplers with stainless steel sampling surfaces and heated enclosure containing an XAD-2 resin adsorption column. Samples were Soxhlet extracted for 24 hours with hexane:acetone (1:1), and concentrated by rotary evaporation. Interferences were removed and the samples separated into analyte groups by silica gel chromatography. Four fractions were collected for GC-ECD and GC-Ion Trap MS analyses. Ten pesticides, 101 PCB congeners, 18 PAHs, and atrazine were measured in all samples. Quality assurance was maintained by including field duplicate samples, field blanks, alboratory matrix spikes, laboratory matrix blanks, and laboratory surrogate spikes in the sampling/analytical protocols. Preliminary results from urban and remote sites show geographical variations in the concentrations of some toxicants due to contributions from local sources. For all sites the total PCB levels are higher in the vapor phase than the particulate phase and show strong seasonal variations. Seasonal variations were also observed for several pesticides.

  15. Sampling and analysis of trace-organic constituents in ambient and workplace air at coal-conversion facilities

    SciTech Connect

    Flotard, R D

    1980-07-01

    A review of the recent literature reveals that current sampling procedures involve the use of glass fiber filters for particulate-sorbed organics and sorbent resins such as Tenax GC and XAD-2 for vapor-phase organics. Ultra trace-organic analysis of air pollutants or particulates may require the collection of a large (1000 to 3000 m/sup 3/) sample by a high volume air sampler. Personal air sampling requires a smaller (approx. = 0.5 m/sup 3/) and a portable collection apparatus. Trapped organic chemicals are recovered by solvent extraction or thermal desorption of the collector. Recovered organics are separated by using liquid chromatography or gas chromatography and are identified by ultraviolet or fluorescence spectroscopy, gas chromatography, or mass spectrometry. For quantification, standards are added to the air stream during sampling or to the filter or resin following sampling. Analysis of the requirement for air sampling in and around coal conversion plants, coupled with the findings of the literature review, indicates that a combined particulate-filter and solvent-extractable-resin sampling unit should be used to collect both particulate-sorbed organics and vapor-phase organics from workplace or ambient plant air. Such a sampler was developed for stationary, moderate-to-high-volume air sampling. Descriptions of the sampler are provided together with sampling efficiency information and recommendations for a sampling procedure.

  16. Research on the net amount of air traffic network

    NASA Astrophysics Data System (ADS)

    Hu, Jun; Wu, Zhenya

    2013-03-01

    As accurate prediction of traffic flow states could reduce the congestion possibility, the theoretical study of air traffic was how to determinate the next time the state with fluid mechanics based on random condition. Then, a novel depicting method of air traffic flow is proposed, which calculated the change of net amount in flow conservation equation with discrete time loss queuing, further, it could determine the relationship between flow and density. Compared to the existing general algorithm, the threshold of net amount was presented in the method, and it had good adaptability.

  17. A new analysis system for whole air sampling: description and results from 2013 SENEX

    NASA Astrophysics Data System (ADS)

    Lerner, B. M.; Gilman, J.; Dumas, M.; Hughes, D.; Jaksich, A.; Hatch, C. D.; Graus, M.; Warneke, C.; Apel, E. C.; Hornbrook, R. S.; Holloway, J. S.; De Gouw, J. A.

    2014-12-01

    Accurate measurement of volatile organic compounds (VOCs) in the troposphere is critical for the understanding of emissions and physical and chemical processes that can impact both air quality and climate. Airborne VOC measurements have proven especially challenging due to the requirement of both high sensitivity (pptv) and short sample collection times (≤15 s) to maximize spatial resolution and sampling frequency for targeted plume analysis. The use of stainless steel canisters to collect whole air samples (WAS) for post-flight analysis has been pioneered by the groups of D. Blake and E. Atlas [Blake et al., 1992; Atlas et al., 1993]. For the 2013 Southeast Nexus Study (SENEX), the NOAA ESRL CSD laboratory undertook WAS measurements for the first time. This required the construction of three new, highly-automated, and field-portable instruments designed to sample, analyze, and clean the canisters for re-use. Analysis was performed with a new custom-built gas chromatograph-mass spectrometer system. The instrument pre-concentrates analyte cryostatically into two parallel traps by means of a Stirling engine, a novel technique which obviates the need for liquid nitrogen to reach trapping temperatures of -175C. Here we present an evaluation of the retrieval of target VOC species from WAS canisters. We discuss the effects of humidity and sample age on the analyte, particularly upon C8+ alkane and aromatic species and biogenic species. Finally, we present results from several research flights during SENEX that targeted emissions from oil/natural gas production.

  18. 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 ...

  19. Networking Multiple Autonomous Air and Ocean Vehicles for Oceanographic Research and Monitoring

    NASA Astrophysics Data System (ADS)

    McGillivary, P. A.; Borges de Sousa, J.; Rajan, K.

    2013-12-01

    Autonomous underwater and surface vessels (AUVs and ASVs) are coming into wider use as components of oceanographic research, including ocean observing systems. Unmanned airborne vehicles (UAVs) are now available at modest cost, allowing multiple UAVs to be deployed with multiple AUVs and ASVs. For optimal use good communication and coordination among vehicles is essential. We report on the use of multiple AUVs networked in communication with multiple UAVs. The UAVs are augmented by inferential reasoning software developed at MBARI that allows UAVs to recognize oceanographic fronts and change their navigation and control. This in turn allows UAVs to automatically to map frontal features, as well as to direct AUVs and ASVs to proceed to such features and conduct sampling via onboard sensors to provide validation for airborne mapping. ASVs can also act as data nodes for communication between UAVs and AUVs, as well as collecting data from onboard sensors, while AUVs can sample the water column vertically. This allows more accurate estimation of phytoplankton biomass and productivity, and can be used in conjunction with UAV sampling to determine air-sea flux of gases (e.g. CO2, CH4, DMS) affecting carbon budgets and atmospheric composition. In particular we describe tests in July 2013 conducted off Sesimbra, Portugal in conjunction with the Portuguese Navy by the University of Porto and MBARI with the goal of tracking large fish in the upper water column with coordinated air/surface/underwater measurements. A thermal gradient was observed in the infrared by a low flying UAV, which was used to dispatch an AUV to obtain ground truth to demonstrate the event-response capabilities using such autonomous platforms. Additional field studies in the future will facilitate integration of multiple unmanned systems into research vessel operations. The strength of hardware and software tools described in this study is to permit fundamental oceanographic measurements of both ocean

  20. A Novel Biobjective Risk-Based Model for Stochastic Air Traffic Network Flow Optimization Problem

    PubMed Central

    Cai, Kaiquan; Jia, Yaoguang; Zhu, Yanbo; Xiao, Mingming

    2015-01-01

    Network-wide air traffic flow management (ATFM) is an effective way to alleviate demand-capacity imbalances globally and thereafter reduce airspace congestion and flight delays. The conventional ATFM models assume the capacities of airports or airspace sectors are all predetermined. However, the capacity uncertainties due to the dynamics of convective weather may make the deterministic ATFM measures impractical. This paper investigates the stochastic air traffic network flow optimization (SATNFO) problem, which is formulated as a weighted biobjective 0-1 integer programming model. In order to evaluate the effect of capacity uncertainties on ATFM, the operational risk is modeled via probabilistic risk assessment and introduced as an extra objective in SATNFO problem. Computation experiments using real-world air traffic network data associated with simulated weather data show that presented model has far less constraints compared to stochastic model with nonanticipative constraints, which means our proposed model reduces the computation complexity. PMID:26180842

  1. A Novel Biobjective Risk-Based Model for Stochastic Air Traffic Network Flow Optimization Problem.

    PubMed

    Cai, Kaiquan; Jia, Yaoguang; Zhu, Yanbo; Xiao, Mingming

    2015-01-01

    Network-wide air traffic flow management (ATFM) is an effective way to alleviate demand-capacity imbalances globally and thereafter reduce airspace congestion and flight delays. The conventional ATFM models assume the capacities of airports or airspace sectors are all predetermined. However, the capacity uncertainties due to the dynamics of convective weather may make the deterministic ATFM measures impractical. This paper investigates the stochastic air traffic network flow optimization (SATNFO) problem, which is formulated as a weighted biobjective 0-1 integer programming model. In order to evaluate the effect of capacity uncertainties on ATFM, the operational risk is modeled via probabilistic risk assessment and introduced as an extra objective in SATNFO problem. Computation experiments using real-world air traffic network data associated with simulated weather data show that presented model has far less constraints compared to stochastic model with nonanticipative constraints, which means our proposed model reduces the computation complexity.

  2. Airborne Detection and Quantification of Swine Influenza A Virus in Air Samples Collected Inside, Outside and Downwind from Swine Barns

    PubMed Central

    Corzo, Cesar A.; Culhane, Marie; Dee, Scott; Morrison, Robert B.; Torremorell, Montserrat

    2013-01-01

    Airborne transmission of influenza A virus (IAV) in swine is speculated to be an important route of virus dissemination, but data are scarce. This study attempted to detect and quantify airborne IAV by virus isolation and RRT-PCR in air samples collected under field conditions. This was accomplished by collecting air samples from four acutely infected pig farms and locating air samplers inside the barns, at the external exhaust fans and downwind from the farms at distances up to 2.1 km. IAV was detected in air samples collected in 3 out of 4 farms included in the study. Isolation of IAV was possible from air samples collected inside the barn at two of the farms and in one farm from the exhausted air. Between 13% and 100% of samples collected inside the barns tested RRT-PCR positive with an average viral load of 3.20E+05 IAV RNA copies/m3 of air. Percentage of exhaust positive air samples also ranged between 13% and 100% with an average viral load of 1.79E+04 RNA copies/m3 of air. Influenza virus RNA was detected in air samples collected between 1.5 and 2.1 Km away from the farms with viral levels significantly lower at 4.65E+03 RNA copies/m3. H1N1, H1N2 and H3N2 subtypes were detected in the air samples and the hemagglutinin gene sequences identified in the swine samples matched those in aerosols providing evidence that the viruses detected in the aerosols originated from the pigs in the farms under study. Overall our results indicate that pigs can be a source of IAV infectious aerosols and that these aerosols can be exhausted from pig barns and be transported downwind. The results from this study provide evidence of the risk of aerosol transmission in pigs under field conditions. PMID:23951164

  3. Exploratory Inquiry: Disparate Air Force Base Area Network Architectures

    DTIC Science & Technology

    2005-03-01

    Lieutenant Jamie Sharkey conducted a thesis on the key issues pertaining to Air Force enterprise architecture management. Discussion of...experience in fixed and tactical communications. His first duty station was McGuire AFB, New Jersey followed by assignments to Spangdahlem AB, Germany; the

  4. Toward a global network for persistent organic pollutants in air: results from the GAPS study.

    PubMed

    Pozo, Karla; Harner, Tom; Wania, Frank; Muir, Derek C G; Jones, Kevin C; Barrie, Leonard A

    2006-08-15

    The Global Atmospheric Passive Sampling (GAPS) study aims to demonstrate the feasibility of using passive samplers to assess the spatial distribution of persistent organic pollutants on a worldwide basis. The GAPS network includes more than 40 sites on 7 continents, mainly in background locations, with some representation of urban and agricultural areas. Here we present concentrations of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in polyurethane foam disk samplers, deployed from December 2004 to March 2005. Legacy OCPs such as alpha-HCH (hexachlorocyclohexane), Chlordanes (trans- and cis-Chlordane and trans-Nonachlor), Dieldrin, and dichlorodiphenyltrichloroethane isomers were detected at most sites with some high values that may be related to possible continued use and/or re-emissions related to historic use. Geometric mean (GM) air concentrations (pg/m3) were: 8.5 for sigmaHCH (sum of alpha- and gamma-isomers), 2.6 for sigmaChlordanes, 0.8 for Dieldrin, and 0.8 for p,p'-DDE. Current-use pesticides such as gamma-HCH (lindane) and especially Endosulfan I exhibited more variable and higher concentrations with GMs of 5 and 58, respectively. PCBs and PBDEs were elevated at urban/suburban sites consistent with their historical use pattern. GM concentrations (pg/m3) were 17 for PCBs and 4 for PBDEs. Sampling under GAPS will continue and will eventually allow seasonality effects and longer-term temporal and spatial trends to be evaluated.

  5. Link Performance Analysis for a Proposed Future Architecture of the Air Force Satellite Control Network

    DTIC Science & Technology

    2011-12-01

    Force Institute of Technology Air University Air Education and Training Command In Partial Fulfillment of the Requirements for the Degree of...computing is an interesting approach to link performance prediction. A paper was authored by the Global Educational Network for Spacecraft Operations...GENSO is a conglomerate of multiple ground stations shared by educational organizations most of which need access to LEO spacecraft. As with any

  6. Sorbent-based sampling methods for volatile and semi-volatile organic compounds in air Part 1: Sorbent-based air monitoring options.

    PubMed

    Woolfenden, Elizabeth

    2010-04-16

    Sorbent tubes/traps are widely used in combination with gas chromatographic (GC) analytical methods to monitor the vapour-phase fraction of organic compounds in air. Target compounds range in volatility from acetylene and freons to phthalates and PCBs and include apolar, polar and reactive species. Airborne vapour concentrations will vary depending on the nature of the location, nearby pollution sources, weather conditions, etc. Levels can range from low percent concentrations in stack and vent emissions to low part per trillion (ppt) levels in ultra-clean outdoor locations. Hundreds, even thousands of different compounds may be present in any given atmosphere. GC is commonly used in combination with mass spectrometry (MS) detection especially for environmental monitoring or for screening uncharacterised workplace atmospheres. Given the complexity and variability of organic vapours in air, no one sampling approach suits every monitoring scenario. A variety of different sampling strategies and sorbent media have been developed to address specific applications. Key sorbent-based examples include: active (pumped) sampling onto tubes packed with one or more sorbents held at ambient temperature; diffusive (passive) sampling onto sorbent tubes/cartridges; on-line sampling of air/gas streams into cooled sorbent traps; and transfer of air samples from containers (canisters, Tedlar) bags, etc.) into cooled sorbent focusing traps. Whichever sampling approach is selected, subsequent analysis almost always involves either solvent extraction or thermal desorption (TD) prior to GC(/MS) analysis. The overall performance of the air monitoring method will depend heavily on appropriate selection of key sampling and analytical parameters. This comprehensive review of air monitoring using sorbent tubes/traps is divided into 2 parts. (1) Sorbent-based air sampling option. (2) Sorbent selection and other aspects of optimizing sorbent-based air monitoring methods. The paper presents

  7. Urban air quality assessment using monitoring data of fractionized aerosol samples, chemometrics and meteorological conditions.

    PubMed

    Yotova, Galina I; Tsitouridou, Roxani; Tsakovski, Stefan L; Simeonov, Vasil D

    2016-01-01

    The present article deals with assessment of urban air by using monitoring data for 10 different aerosol fractions (0.015-16 μm) collected at a typical urban site in City of Thessaloniki, Greece. The data set was subject to multivariate statistical analysis (cluster analysis and principal components analysis) and, additionally, to HYSPLIT back trajectory modeling in order to assess in a better way the impact of the weather conditions on the pollution sources identified. A specific element of the study is the effort to clarify the role of outliers in the data set. The reason for the appearance of outliers is strongly related to the atmospheric condition on the particular sampling days leading to enhanced concentration of pollutants (secondary emissions, sea sprays, road and soil dust, combustion processes) especially for ultra fine and coarse particles. It is also shown that three major sources affect the urban air quality of the location studied-sea sprays, mineral dust and anthropogenic influences (agricultural activity, combustion processes, and industrial sources). The level of impact is related to certain extent to the aerosol fraction size. The assessment of the meteorological conditions leads to defining of four downwind patterns affecting the air quality (Pelagic, Western and Central Europe, Eastern and Northeastern Europe and Africa and Southern Europe). Thus, the present study offers a complete urban air assessment taking into account the weather conditions, pollution sources and aerosol fractioning.

  8. Biomimetic air sampling for detection of low concentrations of molecules and bioagents : LDRD 52744 final report.

    SciTech Connect

    Hughes, Robert Clark

    2003-12-01

    Present methods of air sampling for low concentrations of chemicals like explosives and bioagents involve noisy and power hungry collectors with mechanical parts for moving large volumes of air. However there are biological systems that are capable of detecting very low concentrations of molecules with no mechanical moving parts. An example is the silkworm moth antenna which is a highly branched structure where each of 100 branches contains about 200 sensory 'hairs' which have dimensions of 2 microns wide by 100 microns long. The hairs contain about 3000 pores which is where the gas phase molecules enter the aqueous (lymph) phase for detection. Simulations of diffusion of molecules indicate that this 'forest' of hairs is 'designed' to maximize the extraction of the vapor phase molecules. Since typical molecules lose about 4 decades in diffusion constant upon entering the liquid phase, it is important to allow air diffusion to bring the molecule as close to the 'sensor' as possible. The moth acts on concentrations as low as 1000 molecules per cubic cm. (one part in 1e16). A 3-D collection system of these dimensions could be fabricated by micromachining techniques available at Sandia. This LDRD addresses the issues involved with extracting molecules from air onto micromachined structures and then delivering those molecules to microsensors for detection.

  9. On the feasibility of measuring urban air pollution by wireless distributed sensor networks.

    PubMed

    Moltchanov, Sharon; Levy, Ilan; Etzion, Yael; Lerner, Uri; Broday, David M; Fishbain, Barak

    2015-01-01

    Accurate evaluation of air pollution on human-wellbeing requires high-resolution measurements. Standard air quality monitoring stations provide accurate pollution levels but due to their sparse distribution they cannot capture the highly resolved spatial variations within cities. Similarly, dedicated field campaigns can use tens of measurement devices and obtain highly dense spatial coverage but normally deployment has been limited to short periods of no more than few weeks. Nowadays, advances in communication and sensory technologies enable the deployment of dense grids of wireless distributed air monitoring nodes, yet their sensor ability to capture the spatiotemporal pollutant variability at the sub-neighborhood scale has never been thoroughly tested. This study reports ambient measurements of gaseous air pollutants by a network of six wireless multi-sensor miniature nodes that have been deployed in three urban sites, about 150 m apart. We demonstrate the network's capability to capture spatiotemporal concentration variations at an exceptional fine resolution but highlight the need for a frequent in-situ calibration to maintain the consistency of some sensors. Accordingly, a procedure for a field calibration is proposed and shown to improve the system's performance. Overall, our results support the compatibility of wireless distributed sensor networks for measuring urban air pollution at a sub-neighborhood spatial resolution, which suits the requirement for highly spatiotemporal resolved measurements at the breathing-height when assessing exposure to urban air pollution.

  10. Nonuniform air flow in inlets: the effect on filter deposits in the fiber sampling cassette.

    PubMed

    Baron, P A; Chen, C C; Hemenway, D R; O'Shaughnessy, P

    1994-08-01

    Smoke stream studies were combined with a new technique for visualizing a filter deposit from samples used to monitor asbestos or other fibers. Results clearly show the effect of secondary flow vortices within the sampler under anisoaxial sampling conditions. The vortices observed at low wind velocities occur when the inlet axis is situated at angles between 45 degrees and 180 degrees to the motion of the surrounding air. It is demonstrated that the vortices can create a complex nonuniform pattern in the filter deposit, especially when combined with particle settling or electrostatic interactions between the particles and the sampler. Inertial effects also may play a role in the deposit nonuniformity, as well as causing deposition on the cowl surfaces. Changes in the sampler, such as its placement, may reduce these biases. The effects noted are not likely to occur in all sampling situations, but may explain some reports of high variability on asbestos fiber filter samples. The flow patterns observed in this study are applicable to straight, thin-walled inlets. Although only compact particles were used, the air flow patterns and forces involved will have similar effects on fibers of the same aerodynamic diameter.

  11. Exponential stabilization for sampled-data neural-network-based control systems.

    PubMed

    Wu, Zheng-Guang; Shi, Peng; Su, Hongye; Chu, Jian

    2014-12-01

    This paper investigates the problem of sampled-data stabilization for neural-network-based control systems with an optimal guaranteed cost. Using time-dependent Lyapunov functional approach, some novel conditions are proposed to guarantee the closed-loop systems exponentially stable, which fully use the available information about the actual sampling pattern. Based on the derived conditions, the design methods of the desired sampled-data three-layer fully connected feedforward neural-network-based controller are established to obtain the largest sampling interval and the smallest upper bound of the cost function. A practical example is provided to demonstrate the effectiveness and feasibility of the proposed techniques.

  12. Network sampling coverage II: The effect of non-random missing data on network measurement.

    PubMed

    Smith, Jeffrey A; Moody, James; Morgan, Jonathan

    2017-01-01

    Missing data is an important, but often ignored, aspect of a network study. Measurement validity is affected by missing data, but the level of bias can be difficult to gauge. Here, we describe the effect of missing data on network measurement across widely different circumstances. In Part I of this study (Smith and Moody, 2013), we explored the effect of measurement bias due to randomly missing nodes. Here, we drop the assumption that data are missing at random: what happens to estimates of key network statistics when central nodes are more/less likely to be missing? We answer this question using a wide range of empirical networks and network measures. We find that bias is worse when more central nodes are missing. With respect to network measures, Bonacich centrality is highly sensitive to the loss of central nodes, while closeness centrality is not; distance and bicomponent size are more affected than triad summary measures and behavioral homophily is more robust than degree-homophily. With respect to types of networks, larger, directed networks tend to be more robust, but the relation is weak. We end the paper with a practical application, showing how researchers can use our results (translated into a publically available java application) to gauge the bias in their own data.

  13. Polybrominated diphenyl ethers and alternative flame retardants in air and precipitation samples from the northern Lake Victoria region, East Africa.

    PubMed

    Arinaitwe, Kenneth; Muir, Derek C G; Kiremire, Bernard T; Fellin, Phil; Li, Henrik; Teixeira, Camilla

    2014-01-01

    High volume air and precipitation samples were collected close to the shore of Lake Victoria at Entebbe, Uganda, between October 2008 and July 2010 inclusive. Polybrominated diphenyl ethers (PBDEs) and alternative flame retardants (AFRs) were analyzed by GC-MS. BDEs 47, 99, and 209 were the predominant PBDEs with mean concentrations (in air) of 9.84, 4.38, 8.27 pg m(-3) and mean fluxes in precipitation of 3.40, 6.23, and 7.82 ng m(-2) sample(-1), respectively. 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), and hexabromocyclododecane (HBCDD), anti- and syn-Dechlorane plus were detected at levels comparable with those of PBDEs. Both PBDEs and AFRs in air generally increased from 2008 to 2010. Elevated PBDE concentrations in air were associated with slow moving low altitude air masses from the region immediately adjacent to the lake, while low concentrations were mostly associated with fast moving westerly and southwesterly air masses. Analysis of the octa- and nona-BDE profiles suggested photolysis and pyrolytic debromination of BDE-209 in the air samples. The highly halogenated and most abundant PBDEs and AFRs in air also predominated in precipitation samples. This is the first study to report flame retardants in high volume air samples and precipitation in Equatorial Africa.

  14. Glyphosate-rich air samples induce IL-33, TSLP and generate IL-13 dependent airway inflammation.

    PubMed

    Kumar, Sudhir; Khodoun, Marat; Kettleson, Eric M; McKnight, Christopher; Reponen, Tiina; Grinshpun, Sergey A; Adhikari, Atin

    2014-11-05

    Several low weight molecules have often been implicated in the induction of occupational asthma. Glyphosate, a small molecule herbicide, is widely used in the world. There is a controversy regarding a role of glyphosate in developing asthma and rhinitis among farmers, the mechanism of which is unexplored. The aim of this study was to explore the mechanisms of glyphosate induced pulmonary pathology by utilizing murine models and real environmental samples. C57BL/6, TLR4-/-, and IL-13-/- mice inhaled extracts of glyphosate-rich air samples collected on farms during spraying of herbicides or inhaled different doses of glyphosate and ovalbumin. The cellular response, humoral response, and lung function of exposed mice were evaluated. Exposure to glyphosate-rich air samples as well as glyphosate alone to the lungs increased: eosinophil and neutrophil counts, mast cell degranulation, and production of IL-33, TSLP, IL-13, and IL-5. In contrast, in vivo systemic IL-4 production was not increased. Co-administration of ovalbumin with glyphosate did not substantially change the inflammatory immune response. However, IL-13-deficiency resulted in diminished inflammatory response but did not have a significant effect on airway resistance upon methacholine challenge after 7 or 21 days of glyphosate exposure. Glyphosate-rich farm air samples as well as glyphosate alone were found to induce pulmonary IL-13-dependent inflammation and promote Th2 type cytokines, but not IL-4 for glyphosate alone. This study, for the first time, provides evidence for the mechanism of glyphosate-induced occupational lung disease.

  15. Structural Effects of Network Sampling Coverage I: Nodes Missing at Random1

    PubMed Central

    Smith, Jeffrey A.; Moody, James

    2013-01-01

    Network measures assume a census of a well-bounded population. This level of coverage is rarely achieved in practice, however, and we have only limited information on the robustness of network measures to incomplete coverage. This paper examines the effect of node-level missingness on 4 classes of network measures: centrality, centralization, topology and homophily across a diverse sample of 12 empirical networks. We use a Monte Carlo simulation process to generate data with known levels of missingness and compare the resulting network scores to their known starting values. As with past studies (Borgatti et al 2006; Kossinets 2006), we find that measurement bias generally increases with more missing data. The exact rate and nature of this increase, however, varies systematically across network measures. For example, betweenness and Bonacich centralization are quite sensitive to missing data while closeness and in-degree are robust. Similarly, while the tau statistic and distance are difficult to capture with missing data, transitivity shows little bias even with very high levels of missingness. The results are also clearly dependent on the features of the network. Larger, more centralized networks are generally more robust to missing data, but this is especially true for centrality and centralization measures. More cohesive networks are robust to missing data when measuring topological features but not when measuring centralization. Overall, the results suggest that missing data may have quite large or quite small effects on network measurement, depending on the type of network and the question being posed. PMID:24311893

  16. Inside the Mechanics of Network Development: How Competition and Strategy Reorganize European Air Traffic

    NASA Technical Reports Server (NTRS)

    Huber, Hans

    2006-01-01

    Air transport forms complex networks that can be measured in order to understand its structural characteristics and functional properties. Recent models for network growth (i.e., preferential attachment, etc.) remain stochastic and do not seek to understand other network-specific mechanisms that may account for their development in a more microscopic way. Air traffic is made up of many constituent airlines that are either privately or publicly owned and that operate their own networks. They follow more or less similar business policies each. The way these airline networks organize among themselves into distinct traffic distributions reveals complex interaction among them, which in turn can be aggregated into larger (macro-) traffic distributions. Our approach allows for a more deterministic methodology that will assess the impact of airline strategies on the distinct distributions for air traffic, particularly inside Europe. One key question this paper is seeking to answer is whether there are distinct patterns of preferential attachment for given classes of airline networks to distinct types of European airports. Conclusions about the advancing degree of concentration in this industry and the airline operators that accelerate this process can be drawn.

  17. Electrical network method for the thermal or structural characterization of a conducting material sample or structure

    DOEpatents

    Ortiz, M.G.

    1993-06-08

    A method for modeling a conducting material sample or structure system, as an electrical network of resistances in which each resistance of the network is representative of a specific physical region of the system. The method encompasses measuring a resistance between two external leads and using this measurement in a series of equations describing the network to solve for the network resistances for a specified region and temperature. A calibration system is then developed using the calculated resistances at specified temperatures. This allows for the translation of the calculated resistances to a region temperature. The method can also be used to detect and quantify structural defects in the system.

  18. Electrical network method for the thermal or structural characterization of a conducting material sample or structure

    DOEpatents

    Ortiz, Marco G.

    1993-01-01

    A method for modeling a conducting material sample or structure system, as an electrical network of resistances in which each resistance of the network is representative of a specific physical region of the system. The method encompasses measuring a resistance between two external leads and using this measurement in a series of equations describing the network to solve for the network resistances for a specified region and temperature. A calibration system is then developed using the calculated resistances at specified temperatures. This allows for the translation of the calculated resistances to a region temperature. The method can also be used to detect and quantify structural defects in the system.

  19. Size selective isocyanate aerosols personal air sampling using porous plastic foams

    NASA Astrophysics Data System (ADS)

    Khanh Huynh, Cong; Duc, Trinh Vu

    2009-02-01

    As part of a European project (SMT4-CT96-2137), various European institutions specialized in occupational hygiene (BGIA, HSL, IOM, INRS, IST, Ambiente e Lavoro) have established a program of scientific collaboration to develop one or more prototypes of European personal samplers for the collection of simultaneous three dust fractions: inhalable, thoracic and respirable. These samplers based on existing sampling heads (IOM, GSP and cassettes) use Polyurethane Plastic Foam (PUF) according to their porosity to support sampling and separator size of the particles. In this study, the authors present an original application of size selective personal air sampling using chemical impregnated PUF to perform isocyanate aerosols capturing and derivatizing in industrial spray-painting shops.

  20. Atmospheric trace gas measurements with a new clean air sampling system

    SciTech Connect

    Leifer, R.; Sommers, K.; Guggenheim, S.F.

    1981-10-01

    The development of a new clean air sampling system for the Department of Energy's WB-57F aircraft has allowed the analysis of CCl/sub 3/F (Fluorocarbon-11), CCl/sub 2/F/sub 2/ (Fluorocarbon-12), CHClF/sub 2/ (Fluorocarbon-22), C/sub 2/Cl/sub 3/F/sub 3/ (Fluorocarbon-113), CH/sub 4/, CO, CO/sub 2/, N/sub 2/O, CH/sub 3/Cl, CCl/sub 4/, CH/sub 3/CCl/sub 3/, OCS and SF/sub 6/ in tropospheric and stratospheric samples. Samples collected during the interception of the plume from the eruption of Mount St. Helens indicate that OCS was injected into the stratosphere during the eruption. A large CO/sub 2/ gradient was found at 19.2 km on this flight.

  1. Proton transfer pathways in an aspartate-water cluster sampled by a network of discrete states

    NASA Astrophysics Data System (ADS)

    Reidelbach, Marco; Betz, Fridtjof; Mäusle, Raquel Maya; Imhof, Petra

    2016-08-01

    Proton transfer reactions are complex transitions due to the size and flexibility of the hydrogen-bonded networks along which the protons may ;hop;. The combination of molecular dynamics based sampling of water positions and orientations with direct sampling of proton positions is an efficient way to capture the interplay of these degrees of freedom in a transition network. The energetically most favourable pathway in the proton transfer network computed for an aspartate-water cluster shows the pre-orientation of water molecules and aspartate side chains to be a pre-requisite for the subsequent concerted proton transfer to the product state.

  2. Relationship of air sampling rates of semipermeable membrane devices with the properties of organochlorine pesticides.

    PubMed

    Zhu, Xiuhua; Ding, Guanghui; Levy, Walkiria; Jakobi, Gert; Schramm, Karl-Werner

    2011-06-01

    The organochlorine pesticides (OCP) in Eastern-Barvaria at Haidel 1160 m a.s.l. were monitored with a low volume active air sampler and semi-permeable membrane devices (SPMD). The air sampling rates (Rair) of SPMD for OCP were calculated. Quantitative structure-property relationship (QSPR) models of Rair of SPMD were developed for OCP with partial least square (PLS) regression. Quantum chemical descriptors computed by semi-empirical PM6 method were used as predictor variables. The cumulative variance of the dependent variable explained by the PLS components and determined by cross-validation (Q(2)cum), for the optimal models, is 0.637, indicating that the model has good predictive ability and robustness, and could be used to estimate Rair values of OCP. The main factors governing Rair of OCP are intermolecular interactions and the energy required for cave-forming in dissolution of OCP into triolein of SPMD.

  3. Soyuz 23 Return Samples: Assessment of Air Quality Aboard the International Space Station

    NASA Technical Reports Server (NTRS)

    James, John T.

    2011-01-01

    Six mini-grab sample containers (m-GSCs) were returned aboard Soyuz 23 because of concerns that new air pollutants had been present in the air and these were getting into the water recovery system. The Total Organic Carbon Analyzer had been giving increasing readings of total organic carbon (TOC) in the potable water, and it was postulated that an increased load into the system was responsible. The TOC began to decline in late October, 2010. The toxicological assessment of 6 m-GSCs from the ISS is shown in Table 1. The recoveries of 13C-acetone, fluorobenzene, and chlorobenzene from the GSCs averaged 73, 82, and 59%, respectively. We are working to understand the sub-optimal recovery of chlorobenzene.

  4. Adaptive sampling for learning gaussian processes using mobile sensor networks.

    PubMed

    Xu, Yunfei; Choi, Jongeun

    2011-01-01

    This paper presents a novel class of self-organizing sensing agents that adaptively learn an anisotropic, spatio-temporal gaussian process using noisy measurements and move in order to improve the quality of the estimated covariance function. This approach is based on a class of anisotropic covariance functions of gaussian processes introduced to model a broad range of spatio-temporal physical phenomena. The covariance function is assumed to be unknown a priori. Hence, it is estimated by the maximum a posteriori probability (MAP) estimator. The prediction of the field of interest is then obtained based on the MAP estimate of the covariance function. An optimal sampling strategy is proposed to minimize the information-theoretic cost function of the Fisher Information Matrix. Simulation results demonstrate the effectiveness and the adaptability of the proposed scheme.

  5. Adaptive Sampling for Learning Gaussian Processes Using Mobile Sensor Networks

    PubMed Central

    Xu, Yunfei; Choi, Jongeun

    2011-01-01

    This paper presents a novel class of self-organizing sensing agents that adaptively learn an anisotropic, spatio-temporal Gaussian process using noisy measurements and move in order to improve the quality of the estimated covariance function. This approach is based on a class of anisotropic covariance functions of Gaussian processes introduced to model a broad range of spatio-temporal physical phenomena. The covariance function is assumed to be unknown a priori. Hence, it is estimated by the maximum a posteriori probability (MAP) estimator. The prediction of the field of interest is then obtained based on the MAP estimate of the covariance function. An optimal sampling strategy is proposed to minimize the information-theoretic cost function of the Fisher Information Matrix. Simulation results demonstrate the effectiveness and the adaptability of the proposed scheme. PMID:22163785

  6. Radiological background levels found on glass fiber filters used for low-level environmental surveillance air sampling

    SciTech Connect

    Althouse, P. E.

    1998-09-16

    Environmental surveillance of low-level radioactive particles in air requires a thorough understanding of low-level techniques and air sample collection media. High-volume air sampling for radioactive particles around Lawrence Livermore National Laboratory (LLNL) employs glass-fiber filters that are analyzed for gross alpha and gross beta activity and for specific isotopes. This study was conducted to determine the activities of radionuclides contained in blank glass-fiber filters. Data from this study provided a partial explanation of differences between current reported concentrations of radionuclides in air and those reported historically when cellulose filters were used in the LLNL monitoring effort.

  7. Compressive sampling by artificial neural networks for video

    NASA Astrophysics Data System (ADS)

    Szu, Harold; Hsu, Charles; Jenkins, Jeffrey; Reinhardt, Kitt

    2011-06-01

    We describe a smart surveillance strategy for handling novelty changes. Current sensors seem to keep all, redundant or not. The Human Visual System's Hubel-Wiesel (wavelet) edge detection mechanism pays attention to changes in movement, which naturally produce organized sparseness because a stagnant edge is not reported to the brain's visual cortex by retinal neurons. Sparseness is defined as an ordered set of ones (movement or not) relative to zeros that could be pseudo-orthogonal among themselves; then suited for fault tolerant storage and retrieval by means of Associative Memory (AM). The firing is sparse at the change locations. Unlike purely random sparse masks adopted in medical Compressive Sensing, these organized ones have an additional benefit of using the image changes to make retrievable graphical indexes. We coined this organized sparseness as Compressive Sampling; sensing but skipping over redundancy without altering the original image. Thus, we turn illustrate with video the survival tactics which animals that roam the Earth use daily. They acquire nothing but the space-time changes that are important to satisfy specific prey-predator relationships. We have noticed a similarity between the mathematical Compressive Sensing and this biological mechanism used for survival. We have designed a hardware implementation of the Human Visual System's Compressive Sampling scheme. To speed up further, our mixedsignal circuit design of frame differencing is built in on-chip processing hardware. A CMOS trans-conductance amplifier is designed here to generate a linear current output using a pair of differential input voltages from 2 photon detectors for change detection---one for the previous value and the other the subsequent value, ("write" synaptic weight by Hebbian outer products; "read" by inner product & pt. NL threshold) to localize and track the threat targets.

  8. Development of a sampling and analysis method for 4-vinyl-1-cyclohexene in air.

    PubMed

    Kongtip, Pornpimol; Tangprakorn, Bantoon; Yoosook, Witaya; Chantanakul, Suttinun

    2008-01-01

    The purpose of this research was to develop an applicable sampling and analytical method to determine airborne 4-vinyl-1-cyclohexene concentrations which are usually found in the atmosphere of polybutadiene factories. A solid sorbent tube, containing two sections (100 mg in the front and 50 mg in the back) of activated coconut-shell charcoal was chosen for sampling 4-vinyl-1-cyclohexene vapor. The 4-vinyl-1-cyclohexene in the charcoal samples was desorbed with carbon disulfide and analyzed by gas chromatography equipped with a flame ionization detector. The suitable air flow rate, adsorption capacity, sample storage stability, desorption efficiency and reliability of the method for sampling and analysis of 4-vinyl-1-cyclohexene were evaluated. The method was applied to sampling and analysis of 4-vinyl-1-cyclohexene in the rubber industry. The results indicated a suitable air flow rate of 0.3 to 1.5 l/min. The adsorption capacity of 4-vinyl-1-cyclohexene on 100 mg of charcoal was 0.2134 mg. The 4-vinyl-1-cyclohexene adsorbed on the charcoal was stable for 7 d at room temperature or 21 d in a refrigerated condition. The average percent desorption efficiency of 4-vinyl-1-cyclohexene ranged from 90.45% to 97.04% with the loaded amount ranging from 0.412 to 8.250 microg using 1 ml carbon disulfide. The limit of detection of 4-vinyl-1-cyclohexene was 0.044 ng. The average percent recoveries (n=6) of 4-vinyl-1-cyclohexene adsorbed on charcoal ranging from 0.46 to 8.87 microg were 96.78-102.87% with relative standard deviations (RSDs) of 0.34-1.92%, respectively. The concentrations of 4-vinyl-1-cyclohexene ranged from 0.011 to 0.105 mg/m(3) in the working environment of a polybutadiene factory.

  9. Dynamic groundwater monitoring networks: a manageable method for reviewing sampling frequency.

    PubMed

    Moreau-Fournier, Magali F; Daughney, Christopher J

    2012-12-01

    Optimization of a water quality network through a change in sampling frequency is the only way to increase cost-efficiency without any reduction in the robustness of the data. Existing techniques define optimal sampling frequency based on analysis of historical data from the monitoring network under investigation. Their application to a large network comprised of many sites and many monitored parameters is both technical and challenging. This paper presents a simple non-parametric method for reviewing sampling frequency that is consistent with highly censored environmental data and oriented towards reduction of sampling frequency as a cost-saving measure. Based on simple descriptive statistics, the method is applicable to large networks with long time series and many monitored parameters. The method also provides metrics for interpretation of newly collected data, which enables identification of sites for which a future change in sampling frequency may be necessary, ensuring that the monitoring network is both current and adaptive. Application of this method to the New Zealand National Groundwater Monitoring Programme indicates that reduction of sampling frequency at any site would result in a significant loss of information. This paper also discusses the potential for reducing analysis frequency as an alternative to reduction of sampling frequency.

  10. Results of Self-Absorption Study on the Versapor 3000 Filters for Radioactive Particulate Air Sampling

    SciTech Connect

    Barnett, J. Matthew; Cullinan, Valerie I.; Barnett, Debra S.; Trang-Le, Truc LT; Bliss, Mary; Greenwood, Lawrence R.; Ballinger, Marcel Y.

    2009-02-17

    Since the mid-1980s, Pacific Northwest National Laboratory (PNNL) has used a value of 0.85 as the correction factor for self absorption of activity for particulate radioactive air samples collected from building exhaust for environmental monitoring. This value accounts for activity that cannot be detected by direct counting of alpha and beta particles. Emissions can be degraded or blocked by filter fibers for particles buried in the filter material or by inactive dust particles collected with the radioactive particles. These filters are used for monitoring air emissions from PNNL stacks for radioactive particles. This paper describes an effort to re-evaluate self-absorption effects in particulate radioactive air sample filters (Versapor® 3000, 47 mm diameter) used at PNNL. There were two methods used to characterize the samples. Sixty samples were selected from the archive for acid digestion to compare the radioactivity measured by direct gas-flow proportional counting of filters to the results obtained after acid digestion of the filter and counting again by gas-flow proportional detection. Thirty different sample filters were selected for visible light microscopy to evaluate filter loading and particulate characteristics. Mass-loading effects were also considered. Filter ratios were calculated by dividing the initial counts by the post-digestion counts with the expectation that post-digestion counts would be higher because digestion would expose radioactivity embedded in the filter in addition to that on top of the filter. Contrary to expectations, the post digestion readings were almost always lower than initial readings and averaged approximately half the initial readings for both alpha and beta activity. Before and after digestion readings appeared to be related to each other, but with a low coefficient of determination (R^2) value. The ratios had a wide range of values indicating that this method did not provide sufficient precision to quantify self

  11. Probabilistic inference in general graphical models through sampling in stochastic networks of spiking neurons.

    PubMed

    Pecevski, Dejan; Buesing, Lars; Maass, Wolfgang

    2011-12-01

    An important open problem of computational neuroscience is the generic organization of computations in networks of neurons in the brain. We show here through rigorous theoretical analysis that inherent stochastic features of spiking neurons, in combination with simple nonlinear computational operations in specific network motifs and dendritic arbors, enable networks of spiking neurons to carry out probabilistic inference through sampling in general graphical models. In particular, it enables them to carry out probabilistic inference in Bayesian networks with converging arrows ("explaining away") and with undirected loops, that occur in many real-world tasks. Ubiquitous stochastic features of networks of spiking neurons, such as trial-to-trial variability and spontaneous activity, are necessary ingredients of the underlying computational organization. We demonstrate through computer simulations that this approach can be scaled up to neural emulations of probabilistic inference in fairly large graphical models, yielding some of the most complex computations that have been carried out so far in networks of spiking neurons.

  12. A survey of recent results in passive sampling of water and air by semipermeable membrane devices

    USGS Publications Warehouse

    Prest, Harry F.; Huckins, James N.; Petty, Jimmie D.; Herve, Sirpa; Paasivirta, Jaakko; Heinonen, Pertti

    1995-01-01

    A survey is presented of some recent results for passive sampling of water and air for trace organic contaminants using lipid-filled semipermeable membrane devices (SPMDs). Results of water sampling for trace organochlorine compounds using simultaneously exposed SPMDs and the most universally applied biomonitor (bivalves) are discussed. In general, the total amounts of accumulated analytes available for analysis in bivalves and SPMDs were comparable. However, SPMD controls typically had negligible levels of contamination, which was not always the case for transplanted bivalves, even after prolonged depuration prior to exposure. In surveys of the spatial trends of organochlorines at a series of sites, data from bivalves and SPMDs provided the same picture of contaminant distribution and severity. An exception was ionizable contaminants such as the chlorinated phenolic compounds and their transformation products found in pulp mill effluents. In these cases the two monitoring approaches compliment each other, i.e. what is not found in bivalves appears in SPMDs and vice versa. SPMDs have also been applied in environments where biomonitoring is not feasible. SPMDs have shown their utility in studies of trace levels of polyaromatic hydrocarbons by locating and characterizing point sources. An example is given of their application to the calculation of contaminant half-lives from aqueous SPMD residues, a direct measurement of the persistence of contaminants in an environmental compartment. Similarly, results of air sampling with SPMDs in a relatively pristine coastal location are cited which reveal a tremendous enhancement in p,p′-DDE relative to open ocean values.

  13. A New High-Resolution Direction Finding Architecture Using Photonics and Neural Network Signal Processing for Miniature Air Vehicle Applications

    DTIC Science & Technology

    2015-09-01

    RESOLUTION DIRECTION FINDING ARCHITECTURE USING PHOTONICS AND NEURAL NETWORK SIGNAL PROCESSING FOR MINIATURE AIR VEHICLE APPLICATIONS by Robert...RESOLUTION DIRECTION FINDING ARCHITECTURE USING PHOTONICS AND NEURAL NETWORK SIGNAL PROCESSING FOR MINIATURE AIR VEHICLE APPLICATIONS 5. FUNDING...unlimited 12b. DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) This paper investigates the design of an interferometric direction finding receiver

  14. Contemporary-use pesticides in personal air samples during pregnancy and blood samples at delivery among urban minority mothers and newborns.

    PubMed Central

    Whyatt, Robin M; Barr, Dana B; Camann, David E; Kinney, Patrick L; Barr, John R; Andrews, Howard F; Hoepner, Lori A; Garfinkel, Robin; Hazi, Yair; Reyes, Andria; Ramirez, Judyth; Cosme, Yesenia; Perera, Frederica P

    2003-01-01

    We have measured 29 pesticides in plasma samples collected at birth between 1998 and 2001 from 230 mother and newborn pairs enrolled in the Columbia Center for Children's Environmental Health prospective cohort study. Our prior research has shown widespread pesticide use during pregnancy among this urban minority cohort from New York City. We also measured eight pesticides in 48-hr personal air samples collected from the mothers during pregnancy. The following seven pesticides were detected in 48-83% of plasma samples (range, 1-270 pg/g): the organophosphates chlorpyrifos and diazinon, the carbamates bendiocarb and 2-isopropoxyphenol (metabolite of propoxur), and the fungicides dicloran, phthalimide (metabolite of folpet and captan), and tetrahydrophthalimide (metabolite of captan and captafol). Maternal and cord plasma levels were similar and, except for phthalimide, were highly correlated (p < 0.001). Chlorpyrifos, diazinon, and propoxur were detected in 100% of personal air samples (range, 0.7-6,010 ng/m(3)). Diazinon and propoxur levels were significantly higher in the personal air of women reporting use of an exterminator, can sprays, and/or pest bombs during pregnancy compared with women reporting no pesticide use or use of lower toxicity methods only. A significant correlation was seen between personal air level of chlorpyrifos, diazinon, and propoxur and levels of these insecticides or their metabolites in plasma samples (maternal and/or cord, p < 0.05). The fungicide ortho-phenylphenol was also detected in 100% of air samples but was not measured in plasma. The remaining 22 pesticides were detected in 0-45% of air or plasma samples. Chlorpyrifos, diazinon, propoxur, and bendiocarb levels in air and/or plasma decreased significantly between 1998 and 2001. Findings indicate that pesticide exposures are frequent but decreasing and that the pesticides are readily transferred to the developing fetus during pregnancy. PMID:12727605

  15. Sampling of Breathable Air in U.S. Navy Sonar Domes

    DTIC Science & Technology

    1994-03-01

    USS Kidd 4/92 154 ( DDG - 993 ) USS Donald B. Beary (FF- 6/92 41 1085) USS Truett 6/92 149 (FF-1095) USS San Jacinto 6/92 70 (CG-56) USS Hue City 9/92 32...pressure-tight bulkhead in the center of the dome. On the DD-963, and DDG - 993 , and CG-47 class ships (i.e., destroyers and 5 cruisers), samples of dome air...Command. NAVSEA S9165-AH-MMA-010. Technical manual for sonar dome rubber window SDRW-1 for DD-963, DDG - 993 , and CG-47 class vessels. Revision 1,

  16. Evaluation of septum-capped vials for storage of gas samples during air transport.

    PubMed

    Glatzel, Stephan; Well, Reinhard

    2008-01-01

    In order to provide information on the suitability of commonly used gas storage vials for air transport, we tested two vial types on their ability to preserve defined nitrous oxide concentrations and excess pressure when exposed to low pressure, low temperature and puncture by needles. Unlike in Crimp Cap vials, in Exetainers no nitrous oxide loss following low pressure storage was detectable. Tightness of Exetainers following multiple puncture was best using a small needle diameter. Pressure loss following 5, 10, or 25 punctures was lowest in the Exetainers. We conclude that Exetainers are suitable for storing gas samples for an extended period of time during aircraft transport.

  17. 40 CFR Appendix D to Part 58 - Network Design Criteria for Ambient Air Quality Monitoring

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...—Network Design Criteria for Ambient Air Quality Monitoring 1. Monitoring Objectives and Spatial Scales 2.... References 1. Monitoring Objectives and Spatial Scales The purpose of this appendix is to describe monitoring... and path placement, are described in appendix E to this part. 1.2Spatial Scales. (a) To clarify...

  18. 40 CFR Appendix D to Part 58 - Network Design Criteria for Ambient Air Quality Monitoring

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...—Network Design Criteria for Ambient Air Quality Monitoring 1. Monitoring Objectives and Spatial Scales 2.... References 1. Monitoring Objectives and Spatial Scales The purpose of this appendix is to describe monitoring... and path placement, are described in appendix E to this part. 1.2Spatial Scales. (a) To clarify...

  19. 40 CFR Appendix D to Part 58 - Network Design Criteria for Ambient Air Quality Monitoring

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...—Network Design Criteria for Ambient Air Quality Monitoring 1. Monitoring Objectives and Spatial Scales 2.... References 1. Monitoring Objectives and Spatial Scales The purpose of this appendix is to describe monitoring... and path placement, are described in appendix E to this part. 1.2Spatial Scales. (a) To clarify...

  20. U.S. EPA's National Dioxin Air Monitoring Network: Analytical Issues

    EPA Science Inventory

    The U.S. EPA has established a National Dioxin Air Monitoring Network (NDAMN) to determine the temporal and geographical variability of atmospheric chlorinated dibenzo-p-dioxins (CDDs), furans (CDFs), and coplanar polychlorinated biphenyls (PCBs) at rural and non-impacted locatio...

  1. Site location optimization of regional air quality monitoring network in China: methodology and case study.

    PubMed

    Zheng, Junyu; Feng, Xiaoqiong; Liu, Panwei; Zhong, Liuju; Lai, Senchao

    2011-11-01

    Regional air quality monitoring networks (RAQMN) are urgently needed in China due to increasing regional air pollution in city clusters, arising from rapid economic development in recent decades. This paper proposes a methodological framework for site location optimization in designing a RAQMN adapting to air quality management practice in China. The framework utilizes synthetic assessment concentrations developed from simulated data from a regional air quality model in order to simplify the optimal process and to reduce costs. On the basis of analyzing various constraints such as cost and budget, terrain conditions, administrative district, population density and spatial coverage, the framework takes the maximum approximate degree as an optimization objective to achieve site location optimization of a RAQMN. An expert judgment approach was incorporated into the framework to help adjust initial optimization results in order to make the network more practical and representative. A case study was used to demonstrate the application of the framework, indicating that it is feasible to conduct site optimization for a RAQMN design in China. The effects of different combinations of primary and secondary pollutants on site location optimization were investigated. It is suggested that the network design considering both primary and secondary pollutants could better represent regional pollution characteristics and more extensively reflect temporal and spatial variations of regional air quality. The work shown in this study can be used as a reference to guide site location optimization of a RAQMN design in China or other regions of the world.

  2. Representativeness-Based Sampling Network Design for the State of Alaska

    SciTech Connect

    Hoffman, Forrest M; Kumar, Jitendra; Mills, Richard T; HargroveJr., William Walter

    2013-01-01

    Resource and logistical constraints limit the frequency and extent of environmental observations, particularly in the Arctic, necessitating the development of a systematic sampling strategy to maximize coverage and objectively represent environmental variability at desired scales. A quantitative methodology for stratifying sampling domains, informing site selection, and determining the representativeness of measurement sites and networks is described here.

  3. Probabilistic inference using linear Gaussian importance sampling for hybrid Bayesian networks

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Chang, K. C.

    2005-05-01

    Probabilistic inference for Bayesian networks is in general NP-hard using either exact algorithms or approximate methods. However, for very complex networks, only the approximate methods such as stochastic sampling could be used to provide a solution given any time constraint. There are several simulation methods currently available. They include logic sampling (the first proposed stochastic method for Bayesian networks, the likelihood weighting algorithm) the most commonly used simulation method because of its simplicity and efficiency, the Markov blanket scoring method, and the importance sampling algorithm. In this paper, we first briefly review and compare these available simulation methods, then we propose an improved importance sampling algorithm called linear Gaussian importance sampling algorithm for general hybrid model (LGIS). LGIS is aimed for hybrid Bayesian networks consisting of both discrete and continuous random variables with arbitrary distributions. It uses linear function and Gaussian additive noise to approximate the true conditional probability distribution for continuous variable given both its parents and evidence in a Bayesian network. One of the most important features of the newly developed method is that it can adaptively learn the optimal important function from the previous samples. We test the inference performance of LGIS using a 16-node linear Gaussian model and a 6-node general hybrid model. The performance comparison with other well-known methods such as Junction tree (JT) and likelihood weighting (LW) shows that LGIS-GHM is very promising.

  4. A PRINCIPAL COMPONENT ANALYSIS OF THE CLEAN AIR STATUS AND TRENDS NETWORK (CASTNET) AIR CONCENTRATION DATA

    EPA Science Inventory

    The spatial and temporal variability of ambient air concentrations of SO2, SO42-, NO3, HNO3, and NH4+ obtained from EPA's CASTNet was examined using an objective, statistically based technique...

  5. A Portable Low-Cost High Density Sensor Network for Air Quality at London Heathrow Airport

    NASA Astrophysics Data System (ADS)

    Popoola, O. A.; Mead, M. I.; Bright, V. B.; North, R.; Stewart, G.; Kaye, P. H.; Jones, R. L.

    2013-12-01

    The growing demand for air travel in the UK has led to calls for ways to address the effects of increasing activities in airports in London. London Heathrow airport (LHR) is the largest airport in the UK and in recent years has been operating close to full capacity resulting in consideration of building a third runway to ease the burden at the airport. Such an expansion would be subject to meeting several criteria including local air quality challenges. Air quality issues associated with the airport include particulates (e.g. PM2.5, PM10), carbon monoxide (CO), oxides of nitrogen (NO, NO2), sulphur dioxide (SO2) and volatile organic compounds (VOCs), and these are associated with different sources including aircraft activities and road traffic within and outside of the airport. Although it is well known that airports contribute to poor air quality, part of the challenge is to quantify contributions from these different sources. The work presented here shows the utility of low-cost high density sensor networks in addressing this challenge. We have shown in previous studies the application of low-cost electrochemical sensor network instruments in monitoring air quality pollutants including CO, NO and NO2 in an urban environment. In this paper we extend this to include modified versions of these instruments which incorporate additional species such as O3, SO2, VOCs, CO2 as well as size-speciated particulates (0.38 to 17.4 μm). Meteorological data including temperature, relative humidity, wind speed and direction are also recorded. For this paper, we focus on LHR, although the technique has much wider applicability. A network of 30 sensor nodes is being deployed for over 16 months in and around LHR as part of NERC funded Sensor Network for Air Quality (SNAQ) project. We present here some of the early results from the deployment showing source attribution associated with different operational modes at LHR. Regional pollution episodes influenced by macro meteorology are

  6. Exact Identification of the Structure of a Probabilistic Boolean Network from Samples.

    PubMed

    Cheng, Xiaoqing; Mori, Tomoya; Qiu, Yushan; Ching, Wai-Ki; Akutsu, Tatsuya

    2016-01-01

    We study the number of samples required to uniquely determine the structure of a probabilistic Boolean network (PBN), where PBNs are probabilistic extensions of Boolean networks. We show via theoretical analysis and computational analysis that the structure of a PBN can be exactly identified with high probability from a relatively small number of samples for interesting classes of PBNs of bounded indegree. On the other hand, we also show that there exist classes of PBNs for which it is impossible to uniquely determine the structure of a PBN from samples.

  7. Detection of pollen grains in multifocal optical microscopy images of air samples.

    PubMed

    Landsmeer, Sander H; Hendriks, Emile A; de Weger, Letty A; Reiber, Johan H C; Stoel, Berend C

    2009-06-01

    Pollen is a major cause of allergy and monitoring pollen in the air is relevant for diagnostic purposes, development of pollen forecasts, and for biomedical and biological researches. Since counting airborne pollen is a time-consuming task and requires specialized personnel, an automated pollen counting system is desirable. In this article, we present a method for detecting pollen in multifocal optical microscopy images of air samples collected by a Burkard pollen sampler, as a first step in an automated pollen counting procedure. Both color and shape information was used to discriminate pollen grains from other airborne material in the images, such as fungal spores and dirt. A training set of 44 images from successive focal planes (stacks) was used to train the system in recognizing pollen color and for optimization. The performance of the system has been evaluated using a separate set of 17 image stacks containing 65 pollen grains, of which 86% was detected. The obtained precision of 61% can still be increased in the next step of classifying the different pollen in such a counting system. These results show that the detection of pollen is feasible in images from a pollen sampler collecting ambient air. This first step in automated pollen detection may form a reliable basis for an automated pollen counting system.

  8. Extreme 13C depletion of CCl2F2 in firn air samples from NEEM, Greenland

    NASA Astrophysics Data System (ADS)

    Zuiderweg, A.; Holzinger, R.; Martinerie, P.; Schneider, R.; Kaiser, J.; Witrant, E.; Etheridge, D.; Petrenko, V.; Blunier, T.; Röckmann, T.

    2013-01-01

    A series of 12 high volume air samples collected from the S2 firn core during the North Greenland Eemian Ice Drilling (NEEM) 2009 campaign have been measured for mixing ratio and stable carbon isotope composition of the chlorofluorocarbon CFC-12 (CCl2F2). While the mixing ratio measurements compare favorably to other firn air studies, the isotope results show extreme 13C depletion at the deepest measurable depth (65 m), to values lower than δ13C = -80‰ vs. VPDB (the international stable carbon isotope scale), compared to present day surface tropospheric measurements near -40‰. Firn air modeling was used to interpret these measurements. Reconstructed atmospheric time series indicate even larger depletions (to -120‰) near 1950 AD, with subsequent rapid enrichment of the atmospheric reservoir of the compound to the present day value. Mass-balance calculations show that this change is likely to have been caused by a large change in the isotopic composition of anthropogenic CFC-12 emissions, probably due to technological advances in the CFC production process over the last 80 yr, though direct evidence is lacking.

  9. Extreme 13C depletion of CCl2F2 in firn air samples from NEEM, Greenland

    NASA Astrophysics Data System (ADS)

    Zuiderweg, A.; Holzinger, R.; Martinerie, P.; Schneider, R.; Kaiser, J.; Witrant, E.; Etheridge, D.; Rubino, M.; Petrenko, V.; Blunier, T.; Röckmann, T.

    2012-07-01

    A series of 12 high volume air samples collected from the S2 firn core during the North Greenland Eemian Ice Drilling (NEEM) 2009 campaign have been measured for mixing ratio and stable carbon isotope composition of the chlorofluorocarbon CFC-12 (CCl2F2). While the mixing ratio measurements compare favorably to other firn air studies, the isotope results show extreme 13C depletion at the deepest measurable depth (65 m), to values lower than δ13C = -80‰ vs. VPDB (the international stable carbon isotope scale), compared to present day surface tropospheric measurements near -40‰. Firn air modeling was used to interpret these measurements. Reconstructed atmospheric time series indicate even larger depletions (to -120‰) near 1950 AD, with subsequent rapid enrichment of the atmospheric reservoir of the compound to the present day value. Mass-balance calculations show that this change must have been caused by a large change in the isotopic composition of anthropogenic CFC-12 emissions, probably due to technological changes in the CFC production process over the last 80 yr. Propagating the mass-balance calculations into the future demonstrates that as emissions decrease to zero, isotopic fractionation by the stratospheric sinks will lead to continued 13C enrichment in atmospheric CFC-12.

  10. Network Theory: A Primer and Questions for Air Transportation Systems Applications

    NASA Technical Reports Server (NTRS)

    Holmes, Bruce J.

    2004-01-01

    A new understanding (with potential applications to air transportation systems) has emerged in the past five years in the scientific field of networks. This development emerges in large part because we now have a new laboratory for developing theories about complex networks: The Internet. The premise of this new understanding is that most complex networks of interest, both of nature and of human contrivance, exhibit a fundamentally different behavior than thought for over two hundred years under classical graph theory. Classical theory held that networks exhibited random behavior, characterized by normal, (e.g., Gaussian or Poisson) degree distributions of the connectivity between nodes by links. The new understanding turns this idea on its head: networks of interest exhibit scale-free (or small world) degree distributions of connectivity, characterized by power law distributions. The implications of scale-free behavior for air transportation systems include the potential that some behaviors of complex system architectures might be analyzed through relatively simple approximations of local elements of the system. For air transportation applications, this presentation proposes a framework for constructing topologies (architectures) that represent the relationships between mobility, flight operations, aircraft requirements, and airspace capacity, and the related externalities in airspace procedures and architectures. The proposed architectures or topologies may serve as a framework for posing comparative and combinative analyses of performance, cost, security, environmental, and related metrics.

  11. Flexible sampling large-scale social networks by self-adjustable random walk

    NASA Astrophysics Data System (ADS)

    Xu, Xiao-Ke; Zhu, Jonathan J. H.

    2016-12-01

    Online social networks (OSNs) have become an increasingly attractive gold mine for academic and commercial researchers. However, research on OSNs faces a number of difficult challenges. One bottleneck lies in the massive quantity and often unavailability of OSN population data. Sampling perhaps becomes the only feasible solution to the problems. How to draw samples that can represent the underlying OSNs has remained a formidable task because of a number of conceptual and methodological reasons. Especially, most of the empirically-driven studies on network sampling are confined to simulated data or sub-graph data, which are fundamentally different from real and complete-graph OSNs. In the current study, we propose a flexible sampling method, called Self-Adjustable Random Walk (SARW), and test it against with the population data of a real large-scale OSN. We evaluate the strengths of the sampling method in comparison with four prevailing methods, including uniform, breadth-first search (BFS), random walk (RW), and revised RW (i.e., MHRW) sampling. We try to mix both induced-edge and external-edge information of sampled nodes together in the same sampling process. Our results show that the SARW sampling method has been able to generate unbiased samples of OSNs with maximal precision and minimal cost. The study is helpful for the practice of OSN research by providing a highly needed sampling tools, for the methodological development of large-scale network sampling by comparative evaluations of existing sampling methods, and for the theoretical understanding of human networks by highlighting discrepancies and contradictions between existing knowledge/assumptions of large-scale real OSN data.

  12. Estimation of sampling error uncertainties in observed surface air temperature change in China

    NASA Astrophysics Data System (ADS)

    Hua, Wei; Shen, Samuel S. P.; Weithmann, Alexander; Wang, Huijun

    2016-06-01

    This study examines the sampling error uncertainties in the monthly surface air temperature (SAT) change in China over recent decades, focusing on the uncertainties of gridded data, national averages, and linear trends. Results indicate that large sampling error variances appear at the station-sparse area of northern and western China with the maximum value exceeding 2.0 K2 while small sampling error variances are found at the station-dense area of southern and eastern China with most grid values being less than 0.05 K2. In general, the negative temperature existed in each month prior to the 1980s, and a warming in temperature began thereafter, which accelerated in the early and mid-1990s. The increasing trend in the SAT series was observed for each month of the year with the largest temperature increase and highest uncertainty of 0.51 ± 0.29 K (10 year)-1 occurring in February and the weakest trend and smallest uncertainty of 0.13 ± 0.07 K (10 year)-1 in August. The sampling error uncertainties in the national average annual mean SAT series are not sufficiently large to alter the conclusion of the persistent warming in China. In addition, the sampling error uncertainties in the SAT series show a clear variation compared with other uncertainty estimation methods, which is a plausible reason for the inconsistent variations between our estimate and other studies during this period.

  13. EPA's Response to the February 2014 Release of Radioactive Material from the Waste Isolation Pilot Plant (WIPP): EPA's WIPP Air Sampling Data from April 2014

    EPA Pesticide Factsheets

    In April 2014, U.S. Environmental Protection Agency (EPA) environmental monitoring and assessment team members reviewed DOE's air sampling plan, visited DOE's air samplers and placed air samplers onsite near existing DOE samplers to corroborate results.

  14. An open-access modeled passenger flow matrix for the global air network in 2010.

    PubMed

    Huang, Zhuojie; Wu, Xiao; Garcia, Andres J; Fik, Timothy J; Tatem, Andrew J

    2013-01-01

    The expanding global air network provides rapid and wide-reaching connections accelerating both domestic and international travel. To understand human movement patterns on the network and their socioeconomic, environmental and epidemiological implications, information on passenger flow is required. However, comprehensive data on global passenger flow remain difficult and expensive to obtain, prompting researchers to rely on scheduled flight seat capacity data or simple models of flow. This study describes the construction of an open-access modeled passenger flow matrix for all airports with a host city-population of more than 100,000 and within two transfers of air travel from various publicly available air travel datasets. Data on network characteristics, city population, and local area GDP amongst others are utilized as covariates in a spatial interaction framework to predict the air transportation flows between airports. Training datasets based on information from various transportation organizations in the United States, Canada and the European Union were assembled. A log-linear model controlling the random effects on origin, destination and the airport hierarchy was then built to predict passenger flows on the network, and compared to the results produced using previously published models. Validation analyses showed that the model presented here produced improved predictive power and accuracy compared to previously published models, yielding the highest successful prediction rate at the global scale. Based on this model, passenger flows between 1,491 airports on 644,406 unique routes were estimated in the prediction dataset. The airport node characteristics and estimated passenger flows are freely available as part of the Vector-Borne Disease Airline Importation Risk (VBD-Air) project at: www.vbd-air.com/data.

  15. An Open-Access Modeled Passenger Flow Matrix for the Global Air Network in 2010

    PubMed Central

    Huang, Zhuojie; Wu, Xiao; Garcia, Andres J.; Fik, Timothy J.; Tatem, Andrew J.

    2013-01-01

    The expanding global air network provides rapid and wide-reaching connections accelerating both domestic and international travel. To understand human movement patterns on the network and their socioeconomic, environmental and epidemiological implications, information on passenger flow is required. However, comprehensive data on global passenger flow remain difficult and expensive to obtain, prompting researchers to rely on scheduled flight seat capacity data or simple models of flow. This study describes the construction of an open-access modeled passenger flow matrix for all airports with a host city-population of more than 100,000 and within two transfers of air travel from various publicly available air travel datasets. Data on network characteristics, city population, and local area GDP amongst others are utilized as covariates in a spatial interaction framework to predict the air transportation flows between airports. Training datasets based on information from various transportation organizations in the United States, Canada and the European Union were assembled. A log-linear model controlling the random effects on origin, destination and the airport hierarchy was then built to predict passenger flows on the network, and compared to the results produced using previously published models. Validation analyses showed that the model presented here produced improved predictive power and accuracy compared to previously published models, yielding the highest successful prediction rate at the global scale. Based on this model, passenger flows between 1,491 airports on 644,406 unique routes were estimated in the prediction dataset. The airport node characteristics and estimated passenger flows are freely available as part of the Vector-Borne Disease Airline Importation Risk (VBD-Air) project at: www.vbd-air.com/data. PMID:23691194

  16. Architecture for an integrated real-time air combat and sensor network simulation

    NASA Astrophysics Data System (ADS)

    Criswell, Evans A.; Rushing, John; Lin, Hong; Graves, Sara

    2007-04-01

    An architecture for an integrated air combat and sensor network simulation is presented. The architecture integrates two components: a parallel real-time sensor fusion and target tracking simulation, and an air combat simulation. By integrating these two simulations, it becomes possible to experiment with scenarios in which one or both sides in a battle have very large numbers of primitive passive sensors, and to assess the likely effects of those sensors on the outcome of the battle. Modern Air Power is a real-time theater-level air combat simulation that is currently being used as a part of the USAF Air and Space Basic Course (ASBC). The simulation includes a variety of scenarios from the Vietnam war to the present day, and also includes several hypothetical future scenarios. Modern Air Power includes a scenario editor, an order of battle editor, and full AI customization features that make it possible to quickly construct scenarios for any conflict of interest. The scenario editor makes it possible to place a wide variety of sensors including both high fidelity sensors such as radars, and primitive passive sensors that provide only very limited information. The parallel real-time sensor network simulation is capable of handling very large numbers of sensors on a computing cluster of modest size. It can fuse information provided by disparate sensors to detect and track targets, and produce target tracks.

  17. Cast Stone Oxidation Front Evaluation: Preliminary Results For Samples Exposed To Moist Air

    SciTech Connect

    Langton, C. A.; Almond, P. M.

    2013-11-26

    The rate of oxidation is important to the long-term performance of reducing salt waste forms because the solubility of some contaminants, e.g., technetium, is a function of oxidation state. TcO{sub 4}{sup -} in the salt solution is reduced to Tc(IV) and has been shown to react with ingredients in the waste form to precipitate low solubility sulfide and/or oxide phases. Upon exposure to oxygen, the compounds containing Tc(IV) oxidize to the pertechnetate ion, Tc(VII)O{sub 4}{sup -}, which is very soluble. Consequently the rate of technetium oxidation front advancement into a monolith and the technetium leaching profile as a function of depth from an exposed surface are important to waste form performance and ground water concentration predictions. An approach for measuring contaminant oxidation rate (effective contaminant specific oxidation rate) based on leaching of select contaminants of concern is described in this report. In addition, the relationship between reduction capacity and contaminant oxidation is addressed. Chromate (Cr(VI) was used as a non-radioactive surrogate for pertechnetate, Tc(VII), in Cast Stone samples prepared with 5 M Simulant. Cast Stone spiked with pertechnetate was also prepared and tested. Depth discrete subsamples spiked with Cr were cut from Cast Stone exposed to Savannah River Site (SRS) outdoor ambient temperature fluctuations and moist air. Depth discrete subsamples spiked with Tc-99 were cut from Cast Stone exposed to laboratory ambient temperature fluctuations and moist air. Similar conditions are expected to be encountered in the Cast Stone curing container. The leachability of Cr and Tc-99 and the reduction capacities, measured by the Angus-Glasser method, were determined for each subsample as a function of depth from the exposed surface. The results obtained to date were focused on continued method development and are preliminary and apply to the sample composition and curing / exposure conditions described in this report. The

  18. Ram-air sample collection device for a chemical warfare agent sensor

    DOEpatents

    Megerle, Clifford A.; Adkins, Douglas R.; Frye-Mason, Gregory C.

    2002-01-01

    In a surface acoustic wave sensor mounted within a body, the sensor having a surface acoustic wave array detector and a micro-fabricated sample preconcentrator exposed on a surface of the body, an apparatus for collecting air for the sensor, comprising a housing operatively arranged to mount atop the body, the housing including a multi-stage channel having an inlet and an outlet, the channel having a first stage having a first height and width proximate the inlet, a second stage having a second lower height and width proximate the micro-fabricated sample preconcentrator, a third stage having a still lower third height and width proximate the surface acoustic wave array detector, and a fourth stage having a fourth height and width proximate the outlet, where the fourth height and width are substantially the same as the first height and width.

  19. BIBLE A whole-air sampling as a window on Asian biogeochemistry

    NASA Astrophysics Data System (ADS)

    Elliott, Scott; Blake, Donald R.; Blake, Nicola J.; Dubey, Manvendra K.; Rowland, F. Sherwood; Sive, Barkley C.; Smith, Felisa A.

    2003-02-01

    Asian trace gas and aerosol emissions into carbon, nitrogen, and other elemental cycles will figure prominently in near term Earth system evolution. Atmospheric hydrocarbon measurements resolve numerous chemical species and can be used to investigate sourcing for key geocarriers. A recent aircraft study of biomass burning and lightning (BIBLE A) explored the East Asian atmosphere and was unique in centering on the Indonesian archipelago. Samples of volatile organics taken over/between the islands of Japan, Saipan, Java, and Borneo are here examined as a guide to whole-air-based studies of future Asian biogeochemistry. The midlatitude onshore/offshore pulse and tropical convection strongly influence concentration distributions. As species of increasing molecular weight are considered, rural, combustion, and industrial source regimes emerge. Methane-rich inputs such as waste treatment and rice cultivation are evidenced in the geostrophic outflow. The Indonesian atmosphere is rich in biomass burning markers and also those of vehicular activity. Complexity of air chemistry in the archipelago is a direct reflection of diverse topography, land use, and local economies in a rapidly developing nation. Conspicuous in its absence is the fingerprint for liquefied petroleum gas leakage, but it can be expected to appear as demand for clean fossil fuels rises along with per capita incomes. Combustion tracers indicate high nitrogen mobilization rates, linking regional terrestrial geocycles with open marine ecosystems. Sea to air fluxes are superimposed on continental and marine backgrounds for the methyl halides. However, ocean hot spots are not coordinated and suggest an intricate subsurface kinetics. Levels of long-lived anthropogenic halocarbons attest to the success of international environmental treaties while reactive chlorine containing species track industrial air masses. The dozens of hydrocarbons resolvable by gas chromatographic methods will enable monitoring of

  20. Comparison of air samples, nasal swabs, ear-skin swabs and environmental dust samples for detection of methicillin-resistant Staphylococcus aureus (MRSA) in pig herds.

    PubMed

    Agersø, Y; Vigre, H; Cavaco, L M; Josefsen, M H

    2014-08-01

    To identify a cost-effective and practical method for detection of methicillin-resistant Staphylococcus aureus (MRSA) in pig herds, the relative sensitivity of four sample types: nasal swabs, ear-skin (skin behind the ears) swabs, environmental dust swabs and air was compared. Moreover, dependency of sensitivity on within-herd prevalence was estimated. spa-typing was applied in order to study strain diversity. The sensitivity of one air sample was equal to the sensitivity of ten pools of five nasal swabs and relatively independent of within-herd prevalence [predicted to be nearly perfect (99%) for within-herd prevalence ⩾25%]. The results indicate that taking swabs of skin behind the ears (ten pools of five) was even more sensitive than taking nasal swabs (ten pools of five) at the herd level and detected significantly more positive samples. spa types t011, t034 and t4208 were observed. In conclusion, MRSA detection by air sampling is easy to perform, reduces costs and analytical time compared to existing methods, and is recommended for initial testing of herds. Ear-skin swab sampling may be more sensitive for MRSA detection than air sampling or nasal swab sampling.

  1. Local synchronization of chaotic neural networks with sampled-data and saturating actuators.

    PubMed

    Wu, Zheng-Guang; Shi, Peng; Su, Hongye; Chu, Jian

    2014-12-01

    This paper investigates the problem of local synchronization of chaotic neural networks with sampled-data and actuator saturation. A new time-dependent Lyapunov functional is proposed for the synchronization error systems. The advantage of the constructed Lyapunov functional lies in the fact that it is positive definite at sampling times but not necessarily between sampling times, and makes full use of the available information about the actual sampling pattern. A local stability condition of the synchronization error systems is derived, based on which a sampled-data controller with respect to the actuator saturation is designed to ensure that the master neural networks and slave neural networks are locally asymptotically synchronous. Two optimization problems are provided to compute the desired sampled-data controller with the aim of enlarging the set of admissible initial conditions or the admissible sampling upper bound ensuring the local synchronization of the considered chaotic neural networks. A numerical example is used to demonstrate the effectiveness of the proposed design technique.

  2. Evaluation of physical sampling efficiency for cyclone-based personal bioaerosol samplers in moving air environments.

    PubMed

    Su, Wei-Chung; Tolchinsky, Alexander D; Chen, Bean T; Sigaev, Vladimir I; Cheng, Yung Sung

    2012-09-01

    The need to determine occupational exposure to bioaerosols has notably increased in the past decade, especially for microbiology-related workplaces and laboratories. Recently, two new cyclone-based personal bioaerosol samplers were developed by the National Institute for Occupational Safety and Health (NIOSH) in the USA and the Research Center for Toxicology and Hygienic Regulation of Biopreparations (RCT & HRB) in Russia to monitor bioaerosol exposure in the workplace. Here, a series of wind tunnel experiments were carried out to evaluate the physical sampling performance of these two samplers in moving air conditions, which could provide information for personal biological monitoring in a moving air environment. The experiments were conducted in a small wind tunnel facility using three wind speeds (0.5, 1.0 and 2.0 m s(-1)) and three sampling orientations (0°, 90°, and 180°) with respect to the wind direction. Monodispersed particles ranging from 0.5 to 10 μm were employed as the test aerosols. The evaluation of the physical sampling performance was focused on the aspiration efficiency and capture efficiency of the two samplers. The test results showed that the orientation-averaged aspiration efficiencies of the two samplers closely agreed with the American Conference of Governmental Industrial Hygienists (ACGIH) inhalable convention within the particle sizes used in the evaluation tests, and the effect of the wind speed on the aspiration efficiency was found negligible. The capture efficiencies of these two samplers ranged from 70% to 80%. These data offer important information on the insight into the physical sampling characteristics of the two test samplers.

  3. Fielded ATM network for the Air National Guard Global Yankee Fort Drum exercise

    NASA Astrophysics Data System (ADS)

    Kaminski, Robert L.; Hague, Daniel; Maciag, Chester

    1996-06-01

    This paper will review the deployment, demonstration, and test of an Asynchronous Transfer Mode (ATM) network to support the Air National Guard `Global Yankee' field exercise held at Fort Drum, New York. The network provided forty five (45) megabit per second (mbps) ATM connections between the Air Operations Center (AOC) and Forward Operating Location (FOL) located at Fort Drum, the State University of New York (SUNY) Health Science Center located in Syracuse, New York and Rome Laboratory located in Rome, New York. Connections were made with both fiber and free space equipment. The fiber connections used were part of the existing ATM New York Network (NYNet) between Rome Lab, SUNY Health Science Center and NYNEX Corporation. This network was extended to Watertown, New York by NYNEX to provide connectivity to Fort Drum. The free space links were provided by commercial DS-3 (45 mbps) radios, and 2 to 6 mbps Troposcatter Satellite Support Radios (TSSRs). This paper will also discuss significant digital Command, Control, Communications and Intelligence enhancements to the battlefield provided by the deployed ATM network. For example, videoconferencing and shared workspace capability was demonstrated over the AOC-to-FOL TSSR link, enabling remote intelligence briefings, pilot Battle Damage Assessment, and Search and Rescue coordination. Remote Medical Diagnostics videoconferencing with MRI high resolution digital imagery was demonstrated between the FOL, AOC, and SUNY Health Science Center. Finally, the network provided connectivity between the AOC and the Joint Surveillance System (JSS) radar's located at Griffiss Air Force BAse. The JSS data combined with the Rome Lab developed Radar Analysis Program provided AOC personnel with air picture areas of interest.

  4. 'Pseudomonas saudimassiliensis' sp. nov. a new bacterial species isolated from air samples in the urban environment of Makkah, Saudi Arabia.

    PubMed

    Azhar, E I; Papadioti, A; Bibi, F; Ashshi, A M; Raoult, D; Angelakis, E

    2017-03-01

    We report here the main characteristics of 'Pseudomonas saudimassiliensis' strain 12M76_air(T) (CSUR P1220), a new species of the Pseudomonas genus that was isolated from air samples in the city environment of Makkah, Saudi Arabia, during the pilgrim period of Hajj 2012.

  5. 'Lysinibacillus saudimassiliensis' sp. nov., a new bacterial species isolated from air samples in the urban environment of Makkah, Saudi Arabia.

    PubMed

    Papadioti, A; Azhar, E I; Bibi, F; Jiman-Fatani, A; Aboushoushah, S M; Yasir, M; Raoult, D; Angelakis, E

    2017-03-01

    We report here the main characteristics of 'Lysinibacillus saudimassiliensis' strain 13S34_air(τ) (CSUR = P1222), a new species of the Lysinibacillus genus that was isolated from air samples in the city environment of Makkah, Saudi Arabia, during the pilgrim period of Hajj 2012.

  6. 'Jeotgalicoccus saudimassiliensis' sp. nov., a new bacterial species isolated from air samples in the urban environment of Makkah, Saudi Arabia.

    PubMed

    Papadioti, A; Azhar, E I; Bibi, F; Jiman-Fatani, A; Aboushoushah, S M; Yasir, M; Raoult, D; Angelakis, E

    2017-01-01

    We report here the main characteristics of 'Jeotgalicoccus saudimassiliensis' strain 13MG44_air(T) (CSUR P1221), a new species of the Jeotgalicoccus genus that was isolated from air samples in the city environment of Makkah, Saudi Arabia, during the pilgrim period of Hajj 2012.

  7. 'Arthrobacter saudimassiliensis' sp. nov. a new bacterial species isolated from air samples in the urban environment of Makkah, Saudi Arabia.

    PubMed

    Papadioti, A; Azhar, E I; Bibi, F; Jiman-Fatani, A; Aboushoushah, S M; Yasir, M; Raoult, D; Angelakis, E

    2017-03-01

    We report here the main characteristics of 'Arthrobacter saudimassiliensis' strain 11W110_air(T) (CSUR P1223), a new species of the Arthrobacter genus that was isolated from air samples in the city environment of Makkah, Saudi Arabia, during the pilgrim period of Hajj 2012.

  8. Can the use of deactivated glass fibre filters eliminate sorption artefacts associated with active air sampling of perfluorooctanoic acid?

    PubMed

    Johansson, Jana H; Berger, Urs; Cousins, Ian T

    2017-05-01

    Experimental work was undertaken to test whether gaseous perfluorooctanoic acid (PFOA) sorbs to glass fibre filters (GFFs) during air sampling, causing an incorrect measure of the gas-particle equilibrium distribution. Furthermore, tests were performed to investigate whether deactivation by siliconisation prevents sorption of gaseous PFOA to filter materials. An apparatus was constructed to closely simulate a high-volume air sampler, although with additional features allowing introduction of gaseous test compounds into an air stream stripped from particles. The set-up enabled investigation of the sorption of gaseous test compounds to filter media, eliminating any contribution from particles. Experiments were performed under ambient outdoor air conditions at environmentally relevant analyte concentrations. The results demonstrate that gaseous PFOA sorbs to GFFs, but that breakthrough of gaseous PFOA on the GFFs occurs at trace-level loadings. This indicates that during high volume air sampling, filters do not quantitatively capture all the PFOA in the sampled air. Experiments with siliconised GFFs showed that this filter pre-treatment reduced the sorption of gaseous PFOA, but that sorption still occurred at environmentally relevant air concentrations. We conclude that deactivation of GFFs does not allow for the separation of gaseous and particle bound perfluorinated carboxylic acids (PFCAs) during active air sampling. Consequently, the well-recognised theory that PFCAs do not prevail as gaseous species in the atmosphere may be based on biased measurements. Caution should be taken to ensure that this artefact will not bias the conclusions of future field studies.

  9. Air sampling of aromatic hydrocarbons in the presence of ozone by solid-phase microextraction.

    PubMed

    Xiong, Gouhua; Koziel, Jacek A; Pawliszyn, Janusz

    2004-01-30

    Effects of ozone on air sampling of standard gas mixtures of aromatic hydrocarbons were tested using solid-phase microextraction (SPME). Standard concentrations of ozone ranging from 10 ppb (v/v) to 6400 ppm (v/v) were generated using an in-house built ozone generator based on corona discharge. Effects of temperature, discharge voltage, and oxygen flow on the ozone generation were tested. The working dc voltage had the greatest effect on generated ozone concentration and was proportional to the ozone concentration. Generation temperature and oxygen flow rate were inversely proportional to ozone concentrations. Produced ozone was mixed with standard benzene, toluene, ethylbenzene, and xylenes (BTEX) gas at less than 100 ppb (v/v). Air samples were collected with poly(dimethylsiloxane) (PDMS) 100 microm SPME fibers and analyzed by gas chromatography (GC)-flame ionization detection (FID) and GC-MS. Significant reductions of BTEX concentrations were observed. In addition, some products of BTEX-ozone-oxygen reactions were identified. SPME worked well as a rapid sampler for BTEX and BTEX-ozone-oxygen reaction products. No significant deterioration of the PDMS coating and no significant reduction of absorption capacity were observed after repeated exposure to ozone.

  10. Optimal media for use in air sampling to detect cultivable bacteria and fungi in the pharmacy.

    PubMed

    Weissfeld, Alice S; Joseph, Riya Augustin; Le, Theresa V; Trevino, Ernest A; Schaeffer, M Frances; Vance, Paula H

    2013-10-01

    Current guidelines for air sampling for bacteria and fungi in compounding pharmacies require the use of a medium for each type of organism. U.S. Pharmacopeia (USP) chapter <797> (http://www.pbm.va.gov/linksotherresources/docs/USP797PharmaceuticalCompoundingSterileCompounding.pdf) calls for tryptic soy agar with polysorbate and lecithin (TSApl) for bacteria and malt extract agar (MEA) for fungi. In contrast, the Controlled Environment Testing Association (CETA), the professional organization for individuals who certify hoods and clean rooms, states in its 2012 certification application guide (http://www.cetainternational.org/reference/CAG-009v3.pdf?sid=1267) that a single-plate method is acceptable, implying that it is not always necessary to use an additional medium specifically for fungi. In this study, we reviewed 5.5 years of data from our laboratory to determine the utility of TSApl versus yeast malt extract agar (YMEA) for the isolation of fungi. Our findings, from 2,073 air samples obtained from compounding pharmacies, demonstrated that the YMEA yielded >2.5 times more fungal isolates than TSApl.

  11. Evaluation of bioaerosol sampling techniques for the detection of Chlamydophila psittaci in contaminated air.

    PubMed

    Van Droogenbroeck, Caroline; Van Risseghem, Marleen; Braeckman, Lutgart; Vanrompay, Daisy

    2009-03-16

    Chlamydophila (C.) psittaci, a category B bioterrorism agent, causes respiratory disease in birds and psittacosis or parrot fever in man. The disease spreads aerogenically and no vaccines are available for either birds or man. Highly sensitive C. psittaci bioaerosol monitoring methods are unavailable. We evaluated: (1) dry filtration for collecting C. psittaci from contaminated air using different samplers and membrane filters, (2) impingement into different liquid collection media by use of the AGI-30 impinger and the BioSampler and (3) impaction into newly designed C. psittaci media utilizing the MAS-100 aerosol impactor. For personal bioaerosol sampling, we recommend the use of a gelatin filter in combination with the IOM inhalable dust sampler at an airflow rate of 2L/min. This allowed the detection of 10 organisms of C. psittaci by both PCR and culture. For stationary bioaerosol monitoring, sampling 1000L of air in 10min with the MAS-100 impactor and ChlamyTrap 1 impaction medium was most efficient and made it possible to detect 1 and 10 C. psittaci organisms by PCR and culture, respectively. ChlamyTrap 1 in combination with the MAS-100 impactor might also be applicable for bioaerosol monitoring of viruses.

  12. Evaluating spatial distribution and seasonal variation of phthalates using passive air sampling in southern India.

    PubMed

    Sampath, Srimurali; Selvaraj, Krishna Kumar; Shanmugam, Govindaraj; Krishnamoorthy, Vimalkumar; Chakraborty, Paromita; Ramaswamy, Babu Rajendran

    2017-02-01

    Usage of phthalates as plasticizers has resulted in worldwide occurrence and is becoming a serious concern to human health and environment. However, studies on phthalates in Indian atmosphere are lacking. Therefore, we studied the spatio-temporal trends of six major phthalates in Tamil Nadu, southern India, using passive air samplers. Phthalates were ubiquitously detected in all the samples and the average total phthalates found in decreasing order is pre-monsoon (61 ng m(-3)) > summer (52 ng m(-3)) > monsoon (17 ng m(-3)). Largely used phthalates, dibutylphthalate (DBP) and diethylhexlphthalate (DEHP) were predominantly found in all the seasons with contribution of 11-31% and 59-68%, respectively. The highest total phthalates was observed in summer at an urban location (836 ng m(-3)). Furthermore, through principal component analysis, potential sources were identified as emissions from additives of plasticizers in the polymer industry and the productions of adhesives, building materials and vinyl flooring. Although inhalation exposure of infants was higher than other population segments (toddlers, children and adults), exposure levels were found to be safe for people belonging to all ages based on reference dose (RfD) and tolerable daily intake (TDI) values. This study first attempted to report seasonal trend based on atmospheric monitoring using passive air sampling technique and exposure risk together.

  13. Neural Dynamics as Sampling: A Model for Stochastic Computation in Recurrent Networks of Spiking Neurons

    PubMed Central

    Buesing, Lars; Bill, Johannes; Nessler, Bernhard; Maass, Wolfgang

    2011-01-01

    The organization of computations in networks of spiking neurons in the brain is still largely unknown, in particular in view of the inherently stochastic features of their firing activity and the experimentally observed trial-to-trial variability of neural systems in the brain. In principle there exists a powerful computational framework for stochastic computations, probabilistic inference by sampling, which can explain a large number of macroscopic experimental data in neuroscience and cognitive science. But it has turned out to be surprisingly difficult to create a link between these abstract models for stochastic computations and more detailed models of the dynamics of networks of spiking neurons. Here we create such a link and show that under some conditions the stochastic firing activity of networks of spiking neurons can be interpreted as probabilistic inference via Markov chain Monte Carlo (MCMC) sampling. Since common methods for MCMC sampling in distributed systems, such as Gibbs sampling, are inconsistent with the dynamics of spiking neurons, we introduce a different approach based on non-reversible Markov chains that is able to reflect inherent temporal processes of spiking neuronal activity through a suitable choice of random variables. We propose a neural network model and show by a rigorous theoretical analysis that its neural activity implements MCMC sampling of a given distribution, both for the case of discrete and continuous time. This provides a step towards closing the gap between abstract functional models of cortical computation and more detailed models of networks of spiking neurons. PMID:22096452

  14. Using Neural Networks to Explore Air Traffic Controller Workload

    NASA Technical Reports Server (NTRS)

    Martin, Lynne; Kozon, Thomas; Verma, Savita; Lozito, Sandra C.

    2006-01-01

    When a new system, concept, or tool is proposed in the aviation domain, one concern is the impact that this will have on operator workload. As an experience, workload is difficult to measure in a way that will allow comparison of proposed systems with those already in existence. Chatterji and Sridhar (2001) suggested a method by which airspace parameters can be translated into workload ratings, using a neural network. This approach was employed, and modified to accept input from a non-real time airspace simulation model. The following sections describe the preparations and testing work that will enable comparison of a future airspace concept with a current day baseline in terms of workload levels.

  15. Simple random sampling-based probe station selection for fault detection in wireless sensor networks.

    PubMed

    Huang, Rimao; Qiu, Xuesong; Rui, Lanlan

    2011-01-01

    Fault detection for wireless sensor networks (WSNs) has been studied intensively in recent years. Most existing works statically choose the manager nodes as probe stations and probe the network at a fixed frequency. This straightforward solution leads however to several deficiencies. Firstly, by only assigning the fault detection task to the manager node the whole network is out of balance, and this quickly overloads the already heavily burdened manager node, which in turn ultimately shortens the lifetime of the whole network. Secondly, probing with a fixed frequency often generates too much useless network traffic, which results in a waste of the limited network energy. Thirdly, the traditional algorithm for choosing a probing node is too complicated to be used in energy-critical wireless sensor networks. In this paper, we study the distribution characters of the fault nodes in wireless sensor networks, validate the Pareto principle that a small number of clusters contain most of the faults. We then present a Simple Random Sampling-based algorithm to dynamic choose sensor nodes as probe stations. A dynamic adjusting rule for probing frequency is also proposed to reduce the number of useless probing packets. The simulation experiments demonstrate that the algorithm and adjusting rule we present can effectively prolong the lifetime of a wireless sensor network without decreasing the fault detected rate.

  16. Concentrations of polybrominated diphenyl ethers (PBDEs) in matched samples of human milk, dust and indoor air.

    PubMed

    Toms, Leisa-Maree L; Hearn, Laurence; Kennedy, Karen; Harden, Fiona; Bartkow, Michael; Temme, Christian; Mueller, Jochen F

    2009-08-01

    Polybrominated diphenyl ethers (PBDEs) are lipophilic, persistent pollutants found worldwide in environmental and human samples. Exposure pathways for PBDEs remain unclear but may include food, air and dust. The aim of this study was to conduct an integrated assessment of PBDE exposure and human body burden using 10 matched samples of human milk, indoor air and dust collected in 2007-2008 in Brisbane, Australia. In addition, temporal analysis was investigated comparing the results of the current study with PBDE concentrations in human milk collected in 2002-2003 from the same region. PBDEs were detected in all matrices and the median concentrations of BDEs -47 and -209 in human milk, air and dust were: 4.2 and 0.3 ng/g lipid; 25 and 7.8 pg/m(3); and 56 and 291 ng/g dust, respectively. Significant correlations were observed between the concentrations of BDE-99 in air and human milk (r=0.661, p=0.038) and BDE-153 in dust and BDE-183 in human milk (r=0.697, p=0.025). These correlations do not suggest causal relationships - there is no hypothesis that can be offered to explain why BDE-153 in dust and BDE-183 in milk are correlated. The fact that so few correlations were found in the data could be a function of the small sample size, or because additional factors, such as sources of exposure not considered or measured in the study, might be important in explaining exposure to PBDEs. There was a slight decrease in PBDE concentrations from 2002-2003 to 2007-2008 but this may be due to sampling and analytical differences. Overall, average PBDE concentrations from these individual samples were similar to results from pooled human milk collected in Brisbane in 2002-2003 indicating that pooling may be an efficient, cost-effective strategy of assessing PBDE concentrations on a population basis. The results of this study were used to estimate an infant's daily PBDE intake via inhalation, dust ingestion and human milk consumption. Differences in PBDE intake of individual

  17. Estimation of Distribution Algorithm with Local Sampling Strategy for Community Detection in Complex Networks

    NASA Astrophysics Data System (ADS)

    Yu, Fahong; Li, Wenping; He, Feng; Yu, Bolin; Xia, Xiaoyun; Ma, Longhua

    2016-12-01

    It is important to discover the potential community structure for analyzing complex networks. In this paper, an estimation of distribution algorithm with local sampling strategy for community detection in complex networks is presented to optimize the modularity density function. In the proposed algorithm, the evolution probability model is built according to eminent individuals selected by simulated annealing mechanism and a local sampling strategy based on a local similarity model is adopted to improve both the speed and the accuracy for detecting community structure in complex networks. At the same time, a more general version of the criterion function with a tunable parameter λ is used to avoid the resolution limit. Experiments on synthetic and real-life networks demonstrate the performance and the comparison of experimental results with those of several state-of-the-art methods, the proposed algorithm is considerably efficient and competitive.

  18. A Portable Low-Cost High Density Sensor Network for Air Quality at London Heathrow Airport

    NASA Astrophysics Data System (ADS)

    Popoola, Olalekan; Mead, Iq; Bright, Vivien; Baron, Ronan; Saffell, John; Stewart, Gregor; Kaye, Paul; Jones, Roderic

    2013-04-01

    Outdoor air quality and its impact on human health and the environment have been well studied and it has been projected that poor air quality will surpass poor sanitation as the major course of environmental premature mortality by 2050 (IGAC / IGBP, release statement, 2012). Transport-related pollution has been regulated at various levels by enactment of legislations at local, national, regional and global stages. As part of the mitigation measures, routine measurements of atmospheric pollutants such as carbon monoxide (CO), nitric oxide (NO) and nitrogen dioxide (NO2) have to be established in areas where air quality problems are identified. In addition, emission inventories are also generated for different atmospheric environments including urban areas and airport environments required for air quality models. Whilst recognising that most of the existing sparse monitoring networks provide high temporal measurements, spatial data of these highly variable pollutants are not captured, making it difficult to adequately characterise the highly heterogeneous air quality. Spatial information is often obtained from model data which can only be constrained using measurements from the sparse monitoring networks. The work presented here shows the application of low-cost sensor networks aimed at addressing this missing spatial information. We have shown in previous studies the application of low-cost electrochemical sensor network instruments in monitoring road transport pollutants including CO, NO and NO2 in an urban environment (Mead et. al. 2012, accepted Atmospheric Environment). Modified versions of these instruments which include additional species such as O3, SO2, VOCs and CO2 are currently deployed at London Heathrow Airport (LHR) as part of the Sensor Network for Air Quality (SNAQ) project. Meteorology data such as temperature, relative humidity, wind speed and direction are also measured as well as size-speciated particulates (0.38 to 17.4 µm). A network of 50

  19. Variable sampling approach to mitigate instability in networked control systems with delays.

    PubMed

    López-Echeverría, Daniel; Magaña, Mario E

    2012-01-01

    This paper analyzes a new alternative approach to compensate for the effects of time delays on a dynamic networked control system (NCS). The approach is based on the use of time-delay-predicted values as the sampling times of the NCS. We use a one-step-ahead prediction algorithm based on an adaptive time delay neural network. The application of pole placement and linear quadratic regulator methods to compute the feedback gains taking into account the estimated time delays is investigated.

  20. Development of NO/NO{sub x}/NO{sub y} monitors for urban air sampling

    SciTech Connect

    Kelly, T.J.; Spicer, C.W.; Ward, G.F.

    1994-12-31

    The ideal methodology for NO, NO{sub x}, and NO{sub y} would have the following attributes: compatibility with existing monitoring network facilities and procedures; equipment cost in the range of current network NO{sub x} monitors; capability for specific monitoring of NO, NO{sub 2}, and NO{sub y}; detection limit of 0.1 ppb or lower. This report describes an evaluation of two approaches to meet these monitoring network needs. Both approaches make use of commercially available instruments for detection, with continuous pretreatment of the sample for selectivity. System A makes use of two commercial chemiluminescence instruments to monitor NO, NO{sub y}, and NO{sub 2}. System B utilizes the luminol chemiluminescence reaction to detect NO{sub 2}, and employs multiple catalysts to obtain measurements of NO{sub x} and NO{sub y}. This report describes these two approaches and evaluates them in terms of linearity, converter efficiency, interferences, and detection limits.

  1. Application of zonal model on indoor air sensor network design

    NASA Astrophysics Data System (ADS)

    Chen, Y. Lisa; Wen, Jin

    2007-04-01

    Growing concerns over the safety of the indoor environment have made the use of sensors ubiquitous. Sensors that detect chemical and biological warfare agents can offer early warning of dangerous contaminants. However, current sensor system design is more informed by intuition and experience rather by systematic design. To develop a sensor system design methodology, a proper indoor airflow modeling approach is needed. Various indoor airflow modeling techniques, from complicated computational fluid dynamics approaches to simplified multi-zone approaches, exist in the literature. In this study, the effects of two airflow modeling techniques, multi-zone modeling technique and zonal modeling technique, on indoor air protection sensor system design are discussed. Common building attack scenarios, using a typical CBW agent, are simulated. Both multi-zone and zonal models are used to predict airflows and contaminant dispersion. Genetic Algorithm is then applied to optimize the sensor location and quantity. Differences in the sensor system design resulting from the two airflow models are discussed for a typical office environment and a large hall environment.

  2. ANASORB{reg_sign} 747 - A universal sorbent for air sampling?

    SciTech Connect

    Harper, M.

    1997-12-31

    A sorbent to be used for air sampling must meet certain performance criteria including sample background, capacity, stability, and recovery. Anasorb{sup R} 747 is a proprietary 20/40 mesh beaded active carbon prepared from raw materials with a very low ash content in a process which creates a regular pore structure. The background is very low for both inorganic and organic species, and the surface is more inert and less hydrophilic than coconut charcoal, while capacity is similar. The low catalytic activity of the surface means samples of many reactive compounds remain stable for longer periods. The sorbent is compatible with most solvent systems in use (e.g. carbon disulfide, methylene chloride, methanol, dimethyformamide). Anasorb 747 can be coated with chemicals for efficient adsorption of inorganic gases, which can be analyzed at very low levels because of low background interference. A large number of validated sampling methods use Anasorb 747, including methods from OSHA and NIOSH, corporate industrial hygiene laboratories, various branches of the EPA, and international agencies. These methods refer to around fifty different gases and vapors. Although this sorbent is not compatible with some compounds (e.g. low molecular weight aldehydes) it is quite close to being of universal application.

  3. Sampling cluster stability for peer-to-peer based content distribution networks

    NASA Astrophysics Data System (ADS)

    Darlagiannis, Vasilios; Mauthe, Andreas; Steinmetz, Ralf

    2006-01-01

    Several types of Content Distribution Networks are being deployed over the Internet today, based on different architectures to meet their requirements (e.g., scalability, efficiency and resiliency). Peer-to-Peer (P2P) based Content Distribution Networks are promising approaches that have several advantages. Structured P2P networks, for instance, take a proactive approach and provide efficient routing mechanisms. Nevertheless, their maintenance can increase considerably in highly dynamic P2P environments. In order to address this issue, a two-tier architecture that combines a structured overlay network with a clustering mechanism is suggested in a hybrid scheme. In this paper, we examine several sampling algorithms utilized in the aforementioned hybrid network that collect local information in order to apply a selective join procedure. The algorithms are based mostly on random walks inside the overlay network. The aim of the selective join procedure is to provide a well balanced and stable overlay infrastructure that can easily overcome the unreliable behavior of the autonomous peers that constitute the network. The sampling algorithms are evaluated using simulation experiments where several properties related to the graph structure are revealed.

  4. On the Question of Effective Sample Size in Network Modeling: An Asymptotic Inquiry.

    PubMed

    Kolaczyk, Eric D; Krivitsky, Pavel N

    2015-05-01

    The modeling and analysis of networks and network data has seen an explosion of interest in recent years and represents an exciting direction for potential growth in statistics. Despite the already substantial amount of work done in this area to date by researchers from various disciplines, however, there remain many questions of a decidedly foundational nature - natural analogues of standard questions already posed and addressed in more classical areas of statistics - that have yet to even be posed, much less addressed. Here we raise and consider one such question in connection with network modeling. Specifically, we ask, "Given an observed network, what is the sample size?" Using simple, illustrative examples from the class of exponential random graph models, we show that the answer to this question can very much depend on basic properties of the networks expected under the model, as the number of vertices nV in the network grows. In particular, adopting the (asymptotic) scaling of the variance of the maximum likelihood parameter estimates as a notion of effective sample size, say neff, we show that whether the networks are sparse or not under our model (i.e., having relatively few or many edges between vertices, respectively) is sufficient to yield an order of magnitude difference in neff, from O(nV ) to [Formula: see text]. We then explore some practical implications of this result, using both simulation and data on food-sharing from Lamalera, Indonesia.

  5. Total Particulate Matter Air Sampling Data (TEOM) from Los Alamos National Laboratory

    DOE Data Explorer

    LANL measures the total particulate mass concentration in the air on a routine basis as well as during incidents that may affect ambient air. The collected data is added to the Air Quality Index (AQI). AQI is an index for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. The AQI focuses on health effects you may experience within a few hours or days after breathing polluted air. EPA calculates the AQI for five major air pollutants regulated by the Clean Air Act.

  6. Analysis of the optimal sampling rate for state estimation in sensor networks with delays.

    PubMed

    Martínez-Rey, Miguel; Espinosa, Felipe; Gardel, Alfredo

    2017-03-27

    When addressing the problem of state estimation in sensor networks, the effects of communications on estimator performance are often neglected. High accuracy requires a high sampling rate, but this leads to higher channel load and longer delays, which in turn worsens estimation performance. This paper studies the problem of determining the optimal sampling rate for state estimation in sensor networks from a theoretical perspective that takes into account traffic generation, a model of network behaviour and the effect of delays. Some theoretical results about Riccati and Lyapunov equations applied to sampled systems are derived, and a solution was obtained for the ideal case of perfect sensor information. This result is also interesting for non-ideal sensors, as in some cases it works as an upper bound of the optimisation solution.

  7. Sampled-Data Synchronization Analysis of Markovian Neural Networks With Generally Incomplete Transition Rates.

    PubMed

    Zhang, Huaguang; Wang, Junyi; Wang, Zhanshan; Liang, Hongjing

    2017-03-01

    This paper investigates the problem of sampled-data synchronization for Markovian neural networks with generally incomplete transition rates. Different from traditional Markovian neural networks, each transition rate can be completely unknown or only its estimate value is known in this paper. Compared with most of existing Markovian neural networks, our model is more practical because the transition rates in Markovian processes are difficult to precisely acquire due to the limitations of equipment and the influence of uncertain factors. In addition, the time-dependent Lyapunov-Krasovskii functional is proposed to synchronize drive system and response system. By applying an extended Jensen's integral inequality and Wirtinger's inequality, new delay-dependent synchronization criteria are obtained, which fully utilize the upper bound of variable sampling interval and the sawtooth structure information of varying input delay. Moreover, the desired sampled-data controllers are obtained. Finally, two examples are provided to illustrate the effectiveness of the proposed method.

  8. An evaluation of analytical methods, air sampling techniques, and airborne occupational exposure of metalworking fluids.

    PubMed

    Verma, Dave K; Shaw, Don S; Shaw, M Lorraine; Julian, Jim A; McCollin, Shari-Ann; des Tombe, Karen

    2006-02-01

    This article summarizes an assessment of air sampling and analytical methods for both oil and water-based metalworking fluids (MWFs). Three hundred and seventy-four long-term area and personal airborne samples were collected at four plants using total (closed-face) aerosol samplers and thoracic samplers. A direct-reading device (DustTrak) was also used. The processes sampled include steel tube making, automotive component manufacturing, and small part manufacturing in a machine shop. The American Society for Testing and Materials (ASTM) Method PS42-97 of analysis was evaluated in the laboratory. This evaluation included sample recovery, determination of detection limits, and stability of samples during storage. Results of the laboratory validation showed (a) the sample recovery to be about 87%, (b) the detection limit to be 35 microg, and (c) sample stability during storage at room temperature to decline rapidly within a few days. To minimize sample loss, the samples should be stored in a freezer and analyzed within a week. The ASTM method should be the preferred method for assessing metalworking fluids (MWFs). The ratio of thoracic aerosol to total aerosol ranged from 0.6 to 0.7. A similar relationship was found between the thoracic extractable aerosol and total extractable aerosol. The DustTrak, with 10-microm sampling head, was useful in pinpointing the areas of potential exposure. MWF exposure at the four plants ranged from 0.04 to 3.84 mg/m3 with the geometric mean ranging between 0.22 to 0.59 mg/m3. Based on this data and the assumption of log normality, MWF exposures are expected to exceed the National Institute for Occupational Safety and Health recommended exposure limit of 0.5 mg/m3 as total mass and 0.4 mg/m3 as thoracic mass about 38% of the time. In addition to controlling airborne MWF exposure, full protection of workers would require the institution of programs for fluid management and dermal exposure prevention.

  9. Sampling medium side resistance to uptake of semivolatile organic compounds in passive air samplers.

    PubMed

    Zhang, Xianming; Tsurukawa, Masahiro; Nakano, Takeshi; Lei, Ying D; Wania, Frank

    2011-12-15

    Current theory of the uptake of semivolatile organic compounds in passive air samplers (PAS) assumes uniform chemical distribution and no kinetic resistance within the passive sampling media (PSM) such as polystyrene-divinylbenzene resin (XAD) and polyurethane foam (PUF). However, these assumptions have not been tested experimentally and are challenged by some recently reported observations. To test the assumptions, we performed kinetic uptake experiments indoors using cylindrical PSM that had been concentrically segmented into three layers. Both XAD and PUF were positioned in the same type of sampler housing to eliminate the variation caused by the different housing designs, which enabled us to quantify differences in uptake caused by the properties of the PSM. Duplicated XAD (PUF) samples were retrieved after being deployed for 0, 1 (0.5), 2 (1), 4 (2), 8 (4), 12 (8), and 24 (12) weeks. Upon retrieval, the PSM layers were separated and analyzed individually for PCBs. Passive sampling rates (R) were lower for heavier PCB homologues. Within a homologue group, R for XAD was higher than that for PUF, from which we infer that the design of the "cylindrical can" housing typically used for XAD PAS lowers the R compared to the "double bowl" shelter commonly used for PUF-disk PAS. Outer layers of the PSM sequestered much higher levels of PCBs than inner layers, indicative of a kinetic resistance to chemical transfer within the PSM. The effective diffusivities for chemical transfer within PSM were derived and were found negatively correlated with the partition coefficients between the PSM and air. Based on the results, we conclude that the PSM-side kinetic resistance should be considered when investigating factors influencing R and when deriving R based on the loss of depuration compounds.

  10. Evaluation of sampling methods for toxicological testing of indoor air particulate matter.

    PubMed

    Tirkkonen, Jenni; Täubel, Martin; Hirvonen, Maija-Riitta; Leppänen, Hanna; Lindsley, William G; Chen, Bean T; Hyvärinen, Anne; Huttunen, Kati

    2016-09-01

    There is a need for toxicity tests capable of recognizing indoor environments with compromised air quality, especially in the context of moisture damage. One of the key issues is sampling, which should both provide meaningful material for analyses and fulfill requirements imposed by practitioners using toxicity tests for health risk assessment. We aimed to evaluate different existing methods of sampling indoor particulate matter (PM) to develop a suitable sampling strategy for a toxicological assay. During three sampling campaigns in moisture-damaged and non-damaged school buildings, we evaluated one passive and three active sampling methods: the Settled Dust Box (SDB), the Button Aerosol Sampler, the Harvard Impactor and the National Institute for Occupational Safety and Health (NIOSH) Bioaerosol Cyclone Sampler. Mouse RAW264.7 macrophages were exposed to particle suspensions and cell metabolic activity (CMA), production of nitric oxide (NO) and tumor necrosis factor (TNFα) were determined after 24 h of exposure. The repeatability of the toxicological analyses was very good for all tested sampler types. Variability within the schools was found to be high especially between different classrooms in the moisture-damaged school. Passively collected settled dust and PM collected actively with the NIOSH Sampler (Stage 1) caused a clear response in exposed cells. The results suggested the higher relative immunotoxicological activity of dust from the moisture-damaged school. The NIOSH Sampler is a promising candidate for the collection of size-fractionated PM to be used in toxicity testing. The applicability of such sampling strategy in grading moisture damage severity in buildings needs to be developed further in a larger cohort of buildings.

  11. A water quality monitoring network design methodology for the selection of critical sampling points: Part I.

    PubMed

    Strobl, R O; Robillard, P D; Shannon, R D; Day, R L; McDonnell, A J

    2006-01-01

    The principal instrument to temporally and spatially manage water resources is a water quality monitoring network. However, to date in most cases, there is a clear absence of a concise strategy or methodology for designing monitoring networks, especially when deciding upon the placement of sampling stations. Since water quality monitoring networks can be quite costly, it is very important to properly design the monitoring network so that maximum information extraction can be accomplished, which in turn is vital when informing decision-makers. This paper presents the development of a methodology for identifying the critical sampling locations within a watershed. Hence, it embodies the spatial component in the design of a water quality monitoring network by designating the critical stream locations that should ideally be sampled. For illustration purposes, the methodology focuses on a single contaminant, namely total phosphorus, and is applicable to small, upland, predominantly agricultural-forested watersheds. It takes a number of hydrologic, topographic, soils, vegetative, and land use factors into account. In addition, it includes an economic as well as logistical component in order to approximate the number of sampling points required for a given budget and to only consider the logistically accessible stream reaches in the analysis, respectively. The methodology utilizes a geographic information system (GIS), hydrologic simulation model, and fuzzy logic.

  12. A Low Cost High Density Sensor Network for Air Quality at London Heathrow Airport

    NASA Astrophysics Data System (ADS)

    Bright, V.; Mead, M. I.; Popoola, O. A.; Baron, R. P.; Saffell, J.; Stewart, G.; Kaye, P.; Jones, R.

    2012-12-01

    Atmospheric composition within urban areas has a direct effect on the air quality of an environment in which a large majority of people live and work. Atmospheric pollutants including ozone (O3), nitrogen dioxide (NO2), volatile organic compounds (VOCs) and particulate matter (PM) can have a significant effect on human health. As such it is important to determine the potential exposure of individuals to these atmospheric constituents and investigate the processes that lead to the degradation of air quality within the urban environment. Whilst modelled pollutant levels on the local scale often suggest high degrees of spatial and temporal variability, the relatively sparse fixed site automated urban networks only provide low spatial resolution data that do not appear adequate in detecting such small scale variability. In this paper we demonstrate that measurements can now be made using networks of low-cost sensors that utilise a variety of techniques, including electrochemical and optical, to measure concentrations of atmospheric species. Once equipped with GPS and GPRS to determine position and transmit data respectively, these networks have the potential to provide valuable insights into pollutant variability inherent on the local or micro-scale. The methodology has been demonstrated successfully in field campaigns carried out in cities including London and Valencia, and is now being deployed as part of the Sensor Networks for Air Quality currently deployed at London Heathrow airport (SNAQ-Heathrow) which is outlined in the partner paper presented by Mead et al. (this conference). The SNAQ-Heathrow network of 50 sensor nodes will provide an unprecedented data set that includes measurements of O3, NO, NO2, CO, CO2, SO2, total VOCs, size-speciated PM as well as meteorological variables that include temperature, relative humidity, wind speed and direction. This network will provide high temporal (20 second intervals) and spatial (50 sites within the airport area

  13. 24-HOUR DIFFUSIVE SAMPLING OF TOXIC VOCS IN AIR ONTO CARBOPACK X SOLID ADSORBENT FOLLOWED BY THERMAL DESORPTION/GC/MS ANALYSIS - LABORATORY STUDIES

    EPA Science Inventory

    Diffusive sampling of a mixture of 42 volatile organic compounds (VOCs) in humidified, purified air onto the solid adsorbent Carbopack X was evaluated under controlled laboratory conditions. The evaluation included variations in sample air temperature, relative humidity, and ozon...

  14. CTEPP STANDARD OPERATING PROCEDURE FOR COLLECTION OF FIXED SITE INDOOR AND OUTDOOR AIR SAMPLES FOR PERSISTENT ORGANIC POLLUTANTS (SOP-2.12)

    EPA Science Inventory

    This SOP describes the procedures to set up, calibrate, initiate and terminate air sampling for persistent organic pollutants. This method is used to sample air, indoors and outdoors, at homes and at day care centers over a 48-hr period.

  15. Differential neural network approach in information process for prediction of roadside air pollution by peat fire

    NASA Astrophysics Data System (ADS)

    Lozhkin, V.; Tarkhov, D.; Timofeev, V.; Lozhkina, O.; Vasilyev, A.

    2016-11-01

    The paper presents a novel differential neural network model estimating the dispersion of CO emissions from a peat fire near a highway. We have developed approaches for the optimization of the model on the base of simulated and experimental measurements of CO concentrations in the area of dispersion of the smoke cloud. The numerical solutions of the problem are presented in the form of neural network approximations by the Gaussian model and in the form of neural network approximate solutions of partial differential equations. The trained neural network model can be used for the prediction of emergency when wind speed and direction and other fire parameters are changing. The method is also recommended for the development of air quality monitoring and predicting information systems.

  16. Analysis of feature selection with Probabilistic Neural Network (PNN) to classify sources influencing indoor air quality

    NASA Astrophysics Data System (ADS)

    Saad, S. M.; Shakaff, A. Y. M.; Saad, A. R. M.; Yusof, A. M.; Andrew, A. M.; Zakaria, A.; Adom, A. H.

    2017-03-01

    There are various sources influencing indoor air quality (IAQ) which could emit dangerous gases such as carbon monoxide (CO), carbon dioxide (CO2), ozone (O3) and particulate matter. These gases are usually safe for us to breathe in if they are emitted in safe quantity but if the amount of these gases exceeded the safe level, they might be hazardous to human being especially children and people with asthmatic problem. Therefore, a smart indoor air quality monitoring system (IAQMS) is needed that able to tell the occupants about which sources that trigger the indoor air pollution. In this project, an IAQMS that able to classify sources influencing IAQ has been developed. This IAQMS applies a classification method based on Probabilistic Neural Network (PNN). It is used to classify the sources of indoor air pollution based on five conditions: ambient air, human activity, presence of chemical products, presence of food and beverage, and presence of fragrance. In order to get good and best classification accuracy, an analysis of several feature selection based on data pre-processing method is done to discriminate among the sources. The output from each data pre-processing method has been used as the input for the neural network. The result shows that PNN analysis with the data pre-processing method give good classification accuracy of 99.89% and able to classify the sources influencing IAQ high classification rate.

  17. In vitro effects of pollutants from particulate and volatile fractions of air samples-day and night variability.

    PubMed

    Novák, Jiří; Giesy, John P; Klánová, Jana; Hilscherová, Klára

    2013-09-01

    Chemicals in air were characterized for potential interference with signaling of estrogen, androgen, and arylhydrocarbon (AhR) receptors, which are known to play an important role in endocrine-disruptive changes in vivo. Previously, effects of this type have been studied mainly in particulate matter in the ambient air from various localities. In this study, both volatile and particulate fractions of air from three sites in Banja Luka region (Bosnia and Herzegovina) were investigated to describe the distribution of endocrine-disrupting contaminants on a small spatial scale. Circadian variability of air pollution was investigated by collecting samples during both day and night. Air samples collected from urban localities at night were more potent in producing the AhR-mediated effects than those collected during daytime. This trend was not observed at the reference rural location. None of the samples showed significant estrogenic or androgenic activity. On the other hand, anti-androgenicity was detected in both particulate and vapor phases, while anti-estrogenicity was detected only in the particulate fraction of air from all localities. The AhR-mediated potencies of samples were associated primarily with non-persistent compounds. Based on the concentrations of 28 individual compounds, PAHs accounted for approximately 30 % of the AhR-mediated potency determined by the bioassay. The results show that there can be a significant difference between levels of bioactive compounds in air between daytime and nighttime.

  18. Feasibility study for the modernization of the air quality monitoring network in Venezuela

    SciTech Connect

    1997-11-01

    The project is part of the Ministry of Environment and Recoverable Resources`s (MARNR) goal of establishing a consolidated and effective monitoring program nationwide, which would allow for evaluations of air quality, identification of pollution sources and provide a basis for future air quality management decisions. The bilingual Spanish/English report consists of: (1) work plan; (2) evaluation of current monitoring stations and recommendations for improvement; (3) field evaluation report for existing MARNR network; (4) institutional analysis, revenue requirements, selection of funding mechanism, and three sets of attachments.

  19. Spectral fingerprinting of polycyclic aromatic hydrocarbons in high-volume ambient air samples by constant energy synchronous luminescence spectroscopy

    USGS Publications Warehouse

    Kerkhoff, M.J.; Lee, T.M.; Allen, E.R.; Lundgren, D.A.; Winefordner, J.D.

    1985-01-01

    A high-volume sampler fitted with a glass-fiber filter and backed by polyurethane foam (PUF) was employed to collect airborne particulate and gas-phase polycylic aromatic hydrocarbons (PAHs) in ambient air. Samples were collected from four sources representing a range of environmental conditions: gasoline engine exhaust, diesel engine exhaust, air near a heavily traveled interstate site, and air from a moderately polluted urban site. Spectral fingerprints of the unseparated particulate and gas-phase samples were obtained by constant energy synchronous luminescence spectroscopy (CESLS). Five major PAHs in the gas-phase extracts were characterized and estimated. The compatibility of a high-volume sampling method using polyurethane foam coupled with CESLS detection is explored for use as a screening technique for PAHs in ambient air. ?? 1985 American Chemical Society.

  20. Evaluation of a modified sampling method for molecular analysis of air microflora.

    PubMed

    Lech, T; Ziembinska-Buczynska, A

    2015-04-10

    A serious issue concerning the durability of economically important materials for humans related to cultural heritage is the process of biodeterioration. As a result of this phenomenon, priceless works of art, documents, and old prints have undergone a process of decomposition caused by microorganisms. Therefore, it is important to constantly monitor the presence and diversity of microorganisms in exposition rooms and storage areas of historical objects. In addition, the use of molecular biology tools for conservation studies will enable detailed research as well as reduce the time needed to perform the analyses compared with using conventional methods related to microbiology and conservation. The aim of this study was to adapt the sampling indoor air method for direct DNA extraction from microorganisms, including evaluating the extracted DNA quality and concentration. The obtained DNA was used to study the diversity of mold fungi in indoor air using polymerase chain reaction-denaturing gradient gel electrophoresis in specific archives and museum environments. The research was conducted in 2 storage rooms of the National Archives in Krakow and in 1 exposition room of the Archaeological Museum in Krakow (Poland).

  1. Air-Based Remediation Workshop - Section 1 Sampling And Analysis Revelant To Air-Based Remediation Technologies

    EPA Science Inventory

    Pursant to the EPA-AIT Implementing Arrangement 7 for Technical Environmental Collaboration, Activity 11 "Remediation of Contaminated Sites," the USEPA Office of International Affairs Organized a Force Air Remediation Workshop in Taipei to deliver expert training to the Environme...

  2. Solvent Selection for Pressurized Liquid Extraction of Polymeric Sorbents Used in Air Sampling

    PubMed Central

    Primbs, Toby; Genualdi, Susan; Simonich, Staci

    2014-01-01

    Pressurized liquid extraction (PLE) was evaluated as a method for extracting semivolatile organic compounds (SOCs) from air sampling media; including quartz fiber filter (QFF), polyurethane foam (PUF), and a polystyrene divinyl benzene copolymer (XAD-2). Hansen solubility parameter plots were used to aid in the PLE solvent selection in order to reduce both co-extraction of polyurethane and save time in evaluating solvent compatibility during the initial steps of method development. A PLE solvent composition of 75:25% hexane:acetone was chosen for PUF. The XAD-2 copolymer was not solubilized under the PLE conditions used. The average percent PLE recoveries (and percent relative standard deviations) of 63 SOCs, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine, amide, triazine, thiocarbamate, and phosphorothioate pesticides, were 76.7 (6.2), 79.3 (8.1), and 93.4 (2.9) % for the QFF, PUF, and XAD-2, respectively. PMID:18220448

  3. Sampling of power plant stacks for air toxic emissions: Topical report for Phases 1 and 2

    SciTech Connect

    1995-02-21

    Under contract with the US Department of Energy (DE-AC22-92PCO0367), Pittsburgh Energy Technology Center, Radian Corporation has conducted a test program to collect and analyze size-fractionated stack gas particulate samples for selected inorganic hazardous air pollutants (HAPS). Specific goals of the program are (1) the collection of one-gram quantities of size-fractionated stack gas particulate matter for bulk (total) and surface chemical charactization, and (2) the determination of the relationship between particle size, bulk and surface (leachable) composition, and unit load. The information obtained from this program identifies the effects of unit load, particle size, and wet FGD system operation on the relative toxicological effects of exposure to particulate emissions.

  4. Spectrophotometric determination of nitrogen dioxide in air and nitrite in water and soil samples

    SciTech Connect

    Pandurangappa, M.; Balasubramanian, N.

    1995-02-01

    A sensitive spectrophotometric method for the determination of nitrogen dioxide in air and nitrite in water and soil samples is described. Nitrogen dioxide in air is fixed as nitrite ion in alkaline sodium arsenite or in triethanolamine absorber solutions. The method is based on the diazo coupling reaction between p-nitro aniline and 1-hydroxy-2-naphthoic acid. The azo dye formed under aqueous condition has an absorption maximum at 585nm and obeys Beer`s law over the range 0-25{mu}g of nitrite. The colour system is stable for 72h. The relative standard deviation is 2.7% for ten determinations at 15{mu}g of nitrite. The dye is extracted with 1:1 isoamyl alcohol-IBMK mixture and stabilisation with methanolic potassium hydroxide showed {lambda}{sub max} at 610nm. It obeys Beer`s law over the range 0-4{mu}g of nitrite. The colour system is stable for 40h in organic phase and the relative standard deviation is 2.5% for ten determinations at 3{mu}g of nitrite. The molar absorptivity of the colour system is 3.68 x 10{sup 4} Lmol{sup {minus}1} cm{sup {minus}1}. The effect of interfering gases and other ions on the determination of nitrite is described. The developed method has been applied for the determination of residual nitrogen dioxide gas present in the laboratory fume cupboard and automobile exhaust gases. In addition, the method has been applied for the determination of nitrite and nitrate in samples like water, soil and radiator coolants.

  5. Evaluation of sampling and analytical methods for the determination of chlorodifluoromethane in air.

    PubMed

    Seymour, M J; Lucas, M F

    1993-05-01

    In January 1989, the Occupational Safety and Health Administration (OSHA) published revised permissible exposure limits (PELs) for 212 compounds and established PELs for 164 additional compounds. In cases where regulated compounds did not have specific sampling and analytical methods, methods were suggested by OSHA. The National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods (NMAM) Method 1020, which was developed for 1,1,2-trichloro-1,2,2-trifluoroethane, was suggested by OSHA for the determination of chlorodifluoromethane in workplace air. Because this method was developed for a liquid and chlorodifluoromethane is a gas, the ability of NMAM Method 1020 to adequately sample and quantitate chlorodifluoromethane was questioned and tested by researchers at NIOSH. The evaluation of NMAM Method 1020 for chlorodifluoromethane showed that the capacity of the 100/50-mg charcoal sorbent bed was limited, the standard preparation procedure was incorrect for a gas analyte, and the analyte had low solubility in carbon disulfide. NMAM Method 1018 for dichlorodifluoromethane uses two coconut-shell charcoal tubes in series, a 400/200-mg tube followed by a 100/50-mg tube, which are desorbed with methylene chloride. This method was evaluated for chlorodifluoromethane. Test atmospheres, with chlorodifluoromethane concentrations from 0.5-2 times the PEL were generated. Modifications of NMAM Method 1018 included changes in the standard preparation procedure, and the gas chromatograph was equipped with a capillary column. These revisions to NMAM 1018 resulted in a 96.5% recovery and a total precision for the method of 7.1% for chlorodifluoromethane. No significant bias in the method was found. Results indicate that the revised NMAM Method 1018 is suitable for the determination of chlorodifluoromethane in workplace air.

  6. GUIDE TO CALCULATING TRANSPORT EFFICIENCY OF AEROSOLS IN OCCUPATIONAL AIR SAMPLING SYSTEMS

    SciTech Connect

    Hogue, M.; Hadlock, D.; Thompson, M.; Farfan, E.

    2013-11-12

    This report will present hand calculations for transport efficiency based on aspiration efficiency and particle deposition losses. Because the hand calculations become long and tedious, especially for lognormal distributions of aerosols, an R script (R 2011) will be provided for each element examined. Calculations are provided for the most common elements in a remote air sampling system, including a thin-walled probe in ambient air, straight tubing, bends and a sample housing. One popular alternative approach would be to put such calculations in a spreadsheet, a thorough version of which is shared by Paul Baron via the Aerocalc spreadsheet (Baron 2012). To provide greater transparency and to avoid common spreadsheet vulnerabilities to errors (Burns 2012), this report uses R. The particle size is based on the concept of activity median aerodynamic diameter (AMAD). The AMAD is a particle size in an aerosol where fifty percent of the activity in the aerosol is associated with particles of aerodynamic diameter greater than the AMAD. This concept allows for the simplification of transport efficiency calculations where all particles are treated as spheres with the density of water (1g cm-3). In reality, particle densities depend on the actual material involved. Particle geometries can be very complicated. Dynamic shape factors are provided by Hinds (Hinds 1999). Some example factors are: 1.00 for a sphere, 1.08 for a cube, 1.68 for a long cylinder (10 times as long as it is wide), 1.05 to 1.11 for bituminous coal, 1.57 for sand and 1.88 for talc. Revision 1 is made to correct an error in the original version of this report. The particle distributions are based on activity weighting of particles rather than based on the number of particles of each size. Therefore, the mass correction made in the original version is removed from the text and the calculations. Results affected by the change are updated.

  7. Adaptive sampling rate control for networked systems based on statistical characteristics of packet disordering.

    PubMed

    Li, Jin-Na; Er, Meng-Joo; Tan, Yen-Kheng; Yu, Hai-Bin; Zeng, Peng

    2015-09-01

    This paper investigates an adaptive sampling rate control scheme for networked control systems (NCSs) subject to packet disordering. The main objectives of the proposed scheme are (a) to avoid heavy packet disordering existing in communication networks and (b) to stabilize NCSs with packet disordering, transmission delay and packet loss. First, a novel sampling rate control algorithm based on statistical characteristics of disordering entropy is proposed; secondly, an augmented closed-loop NCS that consists of a plant, a sampler and a state-feedback controller is transformed into an uncertain and stochastic system, which facilitates the controller design. Then, a sufficient condition for stochastic stability in terms of Linear Matrix Inequalities (LMIs) is given. Moreover, an adaptive tracking controller is designed such that the sampling period tracks a desired sampling period, which represents a significant contribution. Finally, experimental results are given to illustrate the effectiveness and advantages of the proposed scheme.

  8. QUALITY ASSURANCE PROGRAM FOR WET DEPOSITION SAMPLING AND CHEMICAL ANALYSES FOR THE NATIONAL TRENDS NETWORK.

    USGS Publications Warehouse

    Schroder, LeRoy J.; Malo, Bernard A.; ,

    1985-01-01

    The purpose of the National Trends Network is to delineate the major inorganic constituents in the wet deposition in the United States. The approach chosen to monitor the Nation's wet deposition is to install approximately 150 automatic sampling devices with at least one collector in each state. Samples are collected at one week intervals, removed from collectors, and transported to an analytical laboratory for chemical analysis. The quality assurance program has divided wet deposition monitoring into 5 parts: (1) Sampling site selection, (2) sampling device, (3) sample container, (4) sample handling, and (5) laboratory analysis. Each of these five components is being examined using existing designs or new designs. Each existing or proposed sampling site is visited and a criteria audit is performed.

  9. Performance evaluation of an importance sampling technique in a Jackson network

    NASA Astrophysics Data System (ADS)

    brahim Mahdipour, E.; Masoud Rahmani, Amir; Setayeshi, Saeed

    2014-03-01

    Importance sampling is a technique that is commonly used to speed up Monte Carlo simulation of rare events. However, little is known regarding the design of efficient importance sampling algorithms in the context of queueing networks. The standard approach, which simulates the system using an a priori fixed change of measure suggested by large deviation analysis, has been shown to fail in even the simplest network settings. Estimating probabilities associated with rare events has been a topic of great importance in queueing theory, and in applied probability at large. In this article, we analyse the performance of an importance sampling estimator for a rare event probability in a Jackson network. This article carries out strict deadlines to a two-node Jackson network with feedback whose arrival and service rates are modulated by an exogenous finite state Markov process. We have estimated the probability of network blocking for various sets of parameters, and also the probability of missing the deadline of customers for different loads and deadlines. We have finally shown that the probability of total population overflow may be affected by various deadline values, service rates and arrival rates.

  10. BOREAS AFM-5 Level-2 Upper Air Network Standard Pressure Level Data

    NASA Technical Reports Server (NTRS)

    Barr, Alan; Hrynkiw, Charmaine; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The BOREAS AFM-5 team collected and processed data from the numerous radiosonde flights during the project. The goals of the AFM-05 team were to provide large-scale definition of the atmosphere by supplementing the existing AES aerological network, both temporally and spatially. This data set includes basic upper-air parameters interpolated at 0.5 kiloPascal increments of atmospheric pressure from data collected from the network of upper-air stations during the 1993, 1994, and 1996 field campaigns over the entire study region. The data are contained in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884) or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  11. The Roland Maze Project school-based extensive air shower network

    NASA Astrophysics Data System (ADS)

    Feder, J.; Jȩdrzejczak, K.; Karczmarczyk, J.; Lewandowski, R.; Swarzyński, J.; Szabelska, B.; Szabelski, J.; Wibig, T.

    2006-01-01

    We plan to construct the large area network of extensive air shower detectors placed on the roofs of high school buildings in the city of Łódź. Detection points will be connected by INTERNET to the central server and their work will be synchronized by GPS. The main scientific goal of the project are studies of ultra high energy cosmic rays. Using existing town infrastructure (INTERNET, power supply, etc.) will significantly reduce the cost of the experiment. Engaging high school students in the research program should significantly increase their knowledge of science and modern technologies, and can be a very efficient way of science popularisation. We performed simulations of the projected network capabilities of registering Extensive Air Showers and reconstructing energies of primary particles. Results of the simulations and the current status of project realisation will be presented.

  12. Automatic Unit Number Binding with Refrigeration Circuit Identification for Air-Conditioner Control Network

    NASA Astrophysics Data System (ADS)

    Ninagawa, Chuzo; Mizoguchi, Masanobu; Tsuji, Kohkichi

    This paper proposes an automatic unit number binding method so that a number of logical subsystems are defined in the whole control network for distributed air-conditioners. Each air-conditioner unit starts the proposed algorithm at random timing to allocate its own unit number without any server. Then each outside unit one by one broadcasts the check signal and flows refrigerant gas to the refrigerant circuit between units to make each inside unit discover its piping connection. As a result, a number of logical subsystems are defined in the whole control network. A Petri net model was constructed for verification of our proposed system. For the case of two outside units and three inside units, the reachability to the required states and the deadlock free property were verified. The generalized module-by-module Petri net construction procedure shows applicability to general cases of arbitrary number of units.

  13. Social Representations of Hero and Everyday Hero: A Network Study from Representative Samples.

    PubMed

    Keczer, Zsolt; File, Bálint; Orosz, Gábor; Zimbardo, Philip G

    2016-01-01

    The psychological investigation of heroism is relatively new. At this stage, inductive methods can shed light on its main aspects. Therefore, we examined the social representations of Hero and Everyday Hero by collecting word associations from two separate representative samples in Hungary. We constructed two networks from these word associations. The results show that the social representation of Hero is more centralized and it cannot be divided into smaller units. The network of Everyday Hero is divided into five units and the significance moves from abstract hero characteristics to concrete social roles and occupations exhibiting pro-social values. We also created networks from the common associations of Hero and Everyday Hero. The structures of these networks show a moderate similarity and the connections are more balanced in case of Everyday Hero. While heroism in general can be the source of inspiration, the promotion of everyday heroism can be more successful in encouraging ordinary people to recognize their own potential for heroic behavior.

  14. Estimating Diffusion Network Structures: Recovery Conditions, Sample Complexity & Soft-thresholding Algorithm

    PubMed Central

    Daneshmand, Hadi; Gomez-Rodriguez, Manuel; Song, Le; Schölkopf, Bernhard

    2015-01-01

    Information spreads across social and technological networks, but often the network structures are hidden from us and we only observe the traces left by the diffusion processes, called cascades. Can we recover the hidden network structures from these observed cascades? What kind of cascades and how many cascades do we need? Are there some network structures which are more difficult than others to recover? Can we design efficient inference algorithms with provable guarantees? Despite the increasing availability of cascade-data and methods for inferring networks from these data, a thorough theoretical understanding of the above questions remains largely unexplored in the literature. In this paper, we investigate the network structure inference problem for a general family of continuous-time diffusion models using an ℓ1-regularized likelihood maximization framework. We show that, as long as the cascade sampling process satisfies a natural incoherence condition, our framework can recover the correct network structure with high probability if we observe O(d3 log N) cascades, where d is the maximum number of parents of a node and N is the total number of nodes. Moreover, we develop a simple and efficient soft-thresholding inference algorithm, which we use to illustrate the consequences of our theoretical results, and show that our framework outperforms other alternatives in practice. PMID:25932466

  15. Validation of in Situ Networks Via Field Sampling: Case Study in the South Fork Experimental Watershed

    NASA Astrophysics Data System (ADS)

    Cosh, M. H.; McKee, L.; Bindlish, R.; Coopersmith, E. J.; Jackson, T. J.; Prueger, J. H.

    2014-12-01

    The calibration and validation of soil moisture remote sensing products is complicated by the logistics of installing a soil moisture network for a long term period in an active landscape. Therefore, these stations are located along field boundaries or in non-representative sites with regards to soil type or soil moisture. The representative character of this network can only be established by large scale field sampling to provide a calibration dataset. A team of samplers were deployed twice a week for the summer of 2014 to collect surface soil moisture data across a variety of land covers at 44 sites. These samples were compared and scaled to the domain to get a better understanding of the large scale soil moisture distributions and dynamics. In addition, comparisons are made to the Soil Moisture Ocean Salinity (SMOS) soil moisture product for the length of the network installation.

  16. Upgrading the North American Upper-Air Observing Network: What are the Possibilities?.

    NASA Astrophysics Data System (ADS)

    Douglas, Michael W.; Stensrud, David J.

    1996-05-01

    The current modernization and restructuring of the National Weather Service (NWS) to date has not involved the rehabilitation of the upper-air observing network over North America. The authors discuss the need for a thorough evaluation of the current upper-air observing system that examines both the old (current) rawinsonde network and newer, remote sensing networks. The key concern is that the meteorological community has given insufficient attention to the scientific questions underlying the choices of observing systems as related to the needs of operational forecasting. The authors argue that the principal basis for a scientific and objective evaluation of observing strategies is the ability of a particular observing system (or component of a system) to improve numerical weather prediction in the modernized NWS. Given this starting point, a number of possible new (and old) observing systems and observing strategies are discussed that offer the possibility for much improved initialization of mesoscale numerical forecast models. Perhaps the key shift in observation strategy suggested is the establishment of many additional radiosonde and pilot balloon sounding stations that rely on contract observers rather than the NWS workforce. However, a comprehensive and satisfactory upgrading of the upper-air observing system will be possible only after more substantial participation of the scientific community in the planning and implementation processes.

  17. Adaptive Preheating Duration Control for Low-Power Ambient Air Quality Sensor Networks

    PubMed Central

    Baek, Yoonchul; Atiq, Mahin K.; Kim, Hyung Seok

    2014-01-01

    Ceramic gas sensors used for measuring ambient air quality have features suitable for practical applications such as healthcare and air quality management, but have a major drawback—large power consumption to preheat the sensor for accurate measurements. In this paper; the adaptive preheating duration control (APC) method is proposed to reduce the power consumption of ambient air quality sensor networks. APC reduces the duration of unnecessary preheating, thereby alleviating power consumption. Furthermore, the APC can allow systems to meet user requirements such as accuracy and periodicity factor when detecting the concentration of a target gas. A performance evaluation of the power consumption of gas sensors is conducted with various user requirements and factors that affect the preheating duration of the gas sensor. This shows that the power consumption of the APC is lower than that of continuous power supply methods and constant power supply/cutoff methods. PMID:24658619

  18. Adaptive preheating duration control for low-power ambient air quality sensor networks.

    PubMed

    Baek, Yoonchul; Atiq, Mahin K; Kim, Hyung Seok

    2014-03-20

    Ceramic gas sensors used for measuring ambient air quality have features suitable for practical applications such as healthcare and air quality management, but have a major drawback-large power consumption to preheat the sensor for accurate measurements. In this paper; the adaptive preheating duration control (APC) method is proposed to reduce the power consumption of ambient air quality sensor networks. APC reduces the duration of unnecessary preheating, thereby alleviating power consumption. Furthermore, the APC can allow systems to meet user requirements such as accuracy and periodicity factor when detecting the concentration of a target gas. A performance evaluation of the power consumption of gas sensors is conducted with various user requirements and factors that affect the preheating duration of the gas sensor. This shows that the power consumption of the APC is lower than that of continuous power supply methods and constant power supply/cutoff methods.

  19. Modeling Air Traffic Management Technologies with a Queuing Network Model of the National Airspace System

    NASA Technical Reports Server (NTRS)

    Long, Dou; Lee, David; Johnson, Jesse; Gaier, Eric; Kostiuk, Peter

    1999-01-01

    This report describes an integrated model of air traffic management (ATM) tools under development in two National Aeronautics and Space Administration (NASA) programs -Terminal Area Productivity (TAP) and Advanced Air Transport Technologies (AATT). The model is made by adjusting parameters of LMINET, a queuing network model of the National Airspace System (NAS), which the Logistics Management Institute (LMI) developed for NASA. Operating LMINET with models of various combinations of TAP and AATT will give quantitative information about the effects of the tools on operations of the NAS. The costs of delays under different scenarios are calculated. An extension of Air Carrier Investment Model (ACIM) under ASAC developed by the Institute for NASA maps the technologies' impacts on NASA operations into cross-comparable benefits estimates for technologies and sets of technologies.

  20. Classifying Sources Influencing Indoor Air Quality (IAQ) Using Artificial Neural Network (ANN)

    PubMed Central

    Mad Saad, Shaharil; Melvin Andrew, Allan; Md Shakaff, Ali Yeon; Mohd Saad, Abdul Rahman; Muhamad Yusof @ Kamarudin, Azman; Zakaria, Ammar

    2015-01-01

    Monitoring indoor air quality (IAQ) is deemed important nowadays. A sophisticated IAQ monitoring system which could classify the source influencing the IAQ is definitely going to be very helpful to the users. Therefore, in this paper, an IAQ monitoring system has been proposed with a newly added feature which enables the system to identify the sources influencing the level of IAQ. In order to achieve this, the data collected has been trained with artificial neural network or ANN—a proven method for pattern recognition. Basically, the proposed system consists of sensor module cloud (SMC), base station and service-oriented client. The SMC contain collections of sensor modules that measure the air quality data and transmit the captured data to base station through wireless network. The IAQ monitoring system is also equipped with IAQ Index and thermal comfort index which could tell the users about the room’s conditions. The results showed that the system is able to measure the level of air quality and successfully classify the sources influencing IAQ in various environments like ambient air, chemical presence, fragrance presence, foods and beverages and human activity. PMID:26007724

  1. Classifying Sources Influencing Indoor Air Quality (IAQ) Using Artificial Neural Network (ANN).

    PubMed

    Saad, Shaharil Mad; Andrew, Allan Melvin; Shakaff, Ali Yeon Md; Saad, Abdul Rahman Mohd; Kamarudin, Azman Muhamad Yusof; Zakaria, Ammar

    2015-05-20

    Monitoring indoor air quality (IAQ) is deemed important nowadays. A sophisticated IAQ monitoring system which could classify the source influencing the IAQ is definitely going to be very helpful to the users. Therefore, in this paper, an IAQ monitoring system has been proposed with a newly added feature which enables the system to identify the sources influencing the level of IAQ. In order to achieve this, the data collected has been trained with artificial neural network or ANN--a proven method for pattern recognition. Basically, the proposed system consists of sensor module cloud (SMC), base station and service-oriented client. The SMC contain collections of sensor modules that measure the air quality data and transmit the captured data to base station through wireless network. The IAQ monitoring system is also equipped with IAQ Index and thermal comfort index which could tell the users about the room's conditions. The results showed that the system is able to measure the level of air quality and successfully classify the sources influencing IAQ in various environments like ambient air, chemical presence, fragrance presence, foods and beverages and human activity.

  2. Uncertainties in Air Exchange using Continuous-Injection, Long-Term Sampling Tracer-Gas Methods

    SciTech Connect

    Sherman, Max H.; Walker, Iain S.; Lunden, Melissa M.

    2013-12-01

    The PerFluorocarbon Tracer (PFT) method is a low-cost approach commonly used for measuring air exchange in buildings using tracer gases. It is a specific application of the more general Continuous-Injection, Long-Term Sampling (CILTS) method. The technique is widely used but there has been little work on understanding the uncertainties (both precision and bias) associated with its use, particularly given that it is typically deployed by untrained or lightly trained people to minimize experimental costs. In this article we will conduct a first-principles error analysis to estimate the uncertainties and then compare that analysis to CILTS measurements that were over-sampled, through the use of multiple tracers and emitter and sampler distribution patterns, in three houses. We find that the CILTS method can have an overall uncertainty of 10-15percent in ideal circumstances, but that even in highly controlled field experiments done by trained experimenters expected uncertainties are about 20percent. In addition, there are many field conditions (such as open windows) where CILTS is not likely to provide any quantitative data. Even avoiding the worst situations of assumption violations CILTS should be considered as having a something like a ?factor of two? uncertainty for the broad field trials that it is typically used in. We provide guidance on how to deploy CILTS and design the experiment to minimize uncertainties.

  3. Volatile N-nitrosamines in environmental tobacco smoke: Sampling, analysis, emission factors, and indoor air exposures

    SciTech Connect

    Mahanama, K.R.R.; Daisey, J.M.

    1996-05-01

    A more convenient sampling and analysis method for the volatile N-nitrosamines (VNA) in environmental tobacco smoke (ETS), using commercially available Thermosorb/N cartridges, was developed and validated. Using the method, emission factors for the two major VNA in ETS were determined in a room-sized environmental chamber for six commercial cigarette brands, which together accounted for 62.5% of the total market in California in 1990. The average emission factors were 565{+-}115 and 104{+-}20 ng per cigarette for N-nitrosodimethylamine and N-nitrosopyrrolidine, respectively. The emission factors were used to estimate VNA exposures from ETS in a typical office building and an average residence. Indoor concentrations of N,N-dimethylnitrosamine from ETS for these modeled scenarios were less than 10% of the reported median outdoor concentration. This median outdoor concentration, however, includes many measurements made in source-dominated areas and may be considerably higher than one based on more representative sampling of outdoor air. 35 refs., 4 tabs.

  4. Sampling of power plant stacks for air toxic emissions: Final report for Phases 1 and 2

    SciTech Connect

    1995-04-28

    A test program to collect and analyze size-fractionated stack gas particulate samples for selected inorganic hazardous air pollutants (HAPs) was conducted . Specific goals of the program are (1) the collection of one-gram quantities of size-fractionated stack gas particulate matter for bulk (total) and surface chemical characterization, and (2) the determination of the relationship between particle size, bulk and surface (leachable) composition, and unit load. The information obtained from this program identifies the effects of unit load, particle size, and wet FGD system operation on the relative toxicological effects of exposure to particulate emissions. Field testing was conducted in two phases. The Phase I field program was performed over the period of August 24 through September 20, 1992, at the Tennessee Valley Authority Widows Creek Unit 8 Power Station, located near Stevenson (Jackson County), Alabama, on the Tennessee River. Sampling activities for Phase II were conducted from September 11 through October 14, 1993. Widows Creek Unit 8 is a 575-megawatt plant that uses bituminous coal averaging 3.7% sulfur and 13% ash. Downstream of the boiler, a venture wet scrubbing system is used for control of both sulfur dioxide and particulate emissions. There is no electrostatic precipitator (ESP) in this system. This system is atypical and represents only about 5% of the US utility industry. However, this site was chosen for this study because of the lack of information available for this particulate emission control system.

  5. Electrical properties of carbon-nanotube-network transistors in air after gamma irradiation

    NASA Astrophysics Data System (ADS)

    Ishii, Satoshi; Yabe, Daisuke; Enomoto, Shotaro; Koshio, Shigeru; Konishi, Teruaki; Hamano, Tsuyoshi; Hirao, Toshio

    2017-02-01

    We experimentally evaluate the electrical properties of carbon nanotube (CNT)-network transistors before and after 60Co gamma-ray irradiation up to 50 kGy in an air environment. When the total dose is increased, the degree of the threshold voltage (Vth) shift towards positive gate voltages in the drain current-gate voltage (ID-VGS) characteristics decreases for total irradiation doses above 30 kGy, although it is constant below 30 kGy. From our analysis of the ID-VGS characteristics along with micro-Raman spectroscopy, the gamma-ray irradiation does not change the structure of the CNT network channel for total doses up to 50 kGy; it instead generates charge traps near the CNT/SiO2 gate insulator interfaces. These traps are located within the SiO2 layer and/or the adsorbate on the device surface. The positively charged traps near the CNT/SiO2 interface contribute less to the Vth shift than the interface dipoles at the CNT/metal electrode interfaces and the segment of the CNT network channel below doses of 30 kGy, while the contribution of the charge traps increases for total doses above 30 kGy. Our findings indicate the possibility of the application of CNT-network transistors as radiation detectors suitable for use in air for radiation doses above 30 kGy.

  6. Networked Estimation for Event-Based Sampling Systems with Packet Dropouts

    PubMed Central

    Nguyen, Vinh Hao; Suh, Young Soo

    2009-01-01

    This paper is concerned with a networked estimation problem in which sensor data are transmitted over the network. In the event-based sampling scheme known as level-crossing or send-on-delta (SOD), sensor data are transmitted to the estimator node if the difference between the current sensor value and the last transmitted one is greater than a given threshold. Event-based sampling has been shown to be more efficient than the time-triggered one in some situations, especially in network bandwidth improvement. However, it cannot detect packet dropout situations because data transmission and reception do not use a periodical time-stamp mechanism as found in time-triggered sampling systems. Motivated by this issue, we propose a modified event-based sampling scheme called modified SOD in which sensor data are sent when either the change of sensor output exceeds a given threshold or the time elapses more than a given interval. Through simulation results, we show that the proposed modified SOD sampling significantly improves estimation performance when packet dropouts happen. PMID:22574063

  7. Uniform Sampling of Steady States in Metabolic Networks: Heterogeneous Scales and Rounding

    PubMed Central

    De Martino, Daniele; Mori, Matteo; Parisi, Valerio

    2015-01-01

    The uniform sampling of convex polytopes is an interesting computational problem with many applications in inference from linear constraints, but the performances of sampling algorithms can be affected by ill-conditioning. This is the case of inferring the feasible steady states in models of metabolic networks, since they can show heterogeneous time scales. In this work we focus on rounding procedures based on building an ellipsoid that closely matches the sampling space, that can be used to define an efficient hit-and-run (HR) Markov Chain Monte Carlo. In this way the uniformity of the sampling of the convex space of interest is rigorously guaranteed, at odds with non markovian methods. We analyze and compare three rounding methods in order to sample the feasible steady states of metabolic networks of three models of growing size up to genomic scale. The first is based on principal component analysis (PCA), the second on linear programming (LP) and finally we employ the Lovazs ellipsoid method (LEM). Our results show that a rounding procedure dramatically improves the performances of the HR in these inference problems and suggest that a combination of LEM or LP with a subsequent PCA perform the best. We finally compare the distributions of the HR with that of two heuristics based on the Artificially Centered hit-and-run (ACHR), gpSampler and optGpSampler. They show a good agreement with the results of the HR for the small network, while on genome scale models present inconsistencies. PMID:25849140

  8. Artificial Neural Network for Total Laboratory Automation to Improve the Management of Sample Dilution.

    PubMed

    Ialongo, Cristiano; Pieri, Massimo; Bernardini, Sergio

    2017-02-01

    Diluting a sample to obtain a measure within the analytical range is a common task in clinical laboratories. However, for urgent samples, it can cause delays in test reporting, which can put patients' safety at risk. The aim of this work is to show a simple artificial neural network that can be used to make it unnecessary to predilute a sample using the information available through the laboratory information system. Particularly, the Multilayer Perceptron neural network built on a data set of 16,106 cardiac troponin I test records produced a correct inference rate of 100% for samples not requiring predilution and 86.2% for those requiring predilution. With respect to the inference reliability, the most relevant inputs were the presence of a cardiac event or surgery and the result of the previous assay. Therefore, such an artificial neural network can be easily implemented into a total automation framework to sensibly reduce the turnaround time of critical orders delayed by the operation required to retrieve, dilute, and retest the sample.

  9. Design for mosquito abundance, diversity, and phenology sampling within the National Ecological Observatory Network

    USGS Publications Warehouse

    Hoekman, D.; Springer, Yuri P; Barker, C.M.; Barrera, R.; Blackmore, M.S.; Bradshaw, W.E.; Foley, D. H.; Ginsberg, Howard; Hayden, M. H.; Holzapfel, C. M.; Juliano, S. A.; Kramer, L. D.; LaDeau, S. L.; Livdahl, T. P.; Moore, C. G.; Nasci, R.S.; Reisen, W.K.; Savage, H. M.

    2016-01-01

    The National Ecological Observatory Network (NEON) intends to monitor mosquito populations across its broad geographical range of sites because of their prevalence in food webs, sensitivity to abiotic factors and relevance for human health. We describe the design of mosquito population sampling in the context of NEON’s long term continental scale monitoring program, emphasizing the sampling design schedule, priorities and collection methods. Freely available NEON data and associated field and laboratory samples, will increase our understanding of how mosquito abundance, demography, diversity and phenology are responding to land use and climate change.

  10. Stability Analysis of Networked Control Systems With Aperiodic Sampling and Time-Varying Delay.

    PubMed

    Chen, Jie; Meng, Su; Sun, Jian

    2016-12-01

    This paper addresses the stability of networked control systems with aperiodic sampling and time-varying network-induced delay. The sampling intervals are assumed to vary within a known interval. The transmission delay is assumed to belong to a given interval. The closed-loop system is first converted to a discrete-time system with multiple time-varying delays and norm-bounded uncertainties resulting from the variation of the sampling intervals. And then, it is transformed into a delay-free system being form of an interconnection of two subsystems. By utilizing scaled small gain theorem, an asymptotic stability criterion for the closed-loop system is proposed in terms of linear matrix inequality. Finally, numerical examples demonstrate the effectiveness of the proposed method and its advantages over existing methods.

  11. Identification of driving network of cellular differentiation from single sample time course gene expression data

    NASA Astrophysics Data System (ADS)

    Chen, Ye; Wolanyk, Nathaniel; Ilker, Tunc; Gao, Shouguo; Wang, Xujing

    Methods developed based on bifurcation theory have demonstrated their potential in driving network identification for complex human diseases, including the work by Chen, et al. Recently bifurcation theory has been successfully applied to model cellular differentiation. However, there one often faces a technical challenge in driving network prediction: time course cellular differentiation study often only contains one sample at each time point, while driving network prediction typically require multiple samples at each time point to infer the variation and interaction structures of candidate genes for the driving network. In this study, we investigate several methods to identify both the critical time point and the driving network through examination of how each time point affects the autocorrelation and phase locking. We apply these methods to a high-throughput sequencing (RNA-Seq) dataset of 42 subsets of thymocytes and mature peripheral T cells at multiple time points during their differentiation (GSE48138 from GEO). We compare the predicted driving genes with known transcription regulators of cellular differentiation. We will discuss the advantages and limitations of our proposed methods, as well as potential further improvements of our methods.

  12. Analysis of quartz by FT-IR in air samples of construction dust.

    PubMed

    Virji, M Abbas; Bello, Dhimiter; Woskie, Susan R; Liu, X Michael; Kalil, Andrew J

    2002-03-01

    The construction industry is reported to have some of the highest exposures to silica-containing dust. With the designation of crystalline silica as a group I human carcinogen by the International Agency for Research on Cancer (IARC), there exists a need for an analytical method to accurately quantify low levels of quartz. A method is described that uses FT-IR for quartz analysis of personal air samples collected from heavy and highway construction sites using 4-stage personal impactors. Sample filters were ashed and 13-mm or 5-mm pellets were prepared. Absorbance spectra were collected using FT-IR at resolution of 1 cm(-1) and 64 scans per spectrum. Two spectra were collected per sample using the appropriate background spectrum subtraction. Spectral manipulations such as Fourier self-deconvolution and derivatizations were performed to improve quantification. Peak height for quartz was measured at 798 cm(-1) for quantitative analysis. The estimated limit of detection for the 5-mm pellets was 1.3 microg. Recoveries of Min-U-Sil 5 spikes showed an average of > or = 94 percent for the two pellet types. The coefficient of variation of the 5-mm pellet was 9 percent at 6 microg quartz load, and 7 percent at 62 microg load. Interferences from clay, amorphous silica, concrete, calcite, and kaolinite were investigated, these being the more likely sources of interferences in construction environment. Spikes of mixtures of amorphous silica or kaolinite with Min-U-Sil 5 showed both contaminants introduced, on average, a positive error of < 5 microg with average recoveries of 106 percent and 111 percent, respectively. Spikes of mixtures of clay or concrete with Min-U-Sil 5 showed overall average recovery of 100 percent and 90 percent, respectively, after accounting for the presence of quartz in clay and concrete. This method can quantify low levels of quartz with reasonable accuracy in the face of common contaminants found in the construction industry.

  13. Air sampling of flame retardants based on the use of mixed-bed sorption tubes--a validation study.

    PubMed

    Lazarov, Borislav; Swinnen, Rudi; Spruyt, Maarten; Maes, Frederick; Van Campenhout, Karen; Goelen, Eddy; Covaci, Adrian; Stranger, Marianne

    2015-11-01

    An analytical methodology using automatic thermal desorption and gas chromatography mass spectrometry analysis was optimized and validated for simultaneous determination of a set of components from three different flame retardant chemical classes: polybrominated diphenyl ethers (PBDEs) (PBDE-28, PBDE-47, PBDE-66, PBDE-85, PBDE-99, PBDE-100), organophosphate flame retardants (PFRs) (tributyl phosphate, tripropyl phosphate, tris(2-chloroethyl)phosphate-, tris(1,3-dichloro-2-propyl) phosphate, tris(2-ethylhexyl) phosphate, triphenyl phosphate, tris(2-chloro-1-methylethyl) phosphate and tricresylphosphate), and "novel" brominated flame retardants (NBFRs) (pentabromotoluene, 2,3,4,5,6-pentabromoethylbenzene, (2,3-dibromopropyl) (2,4,6-tribromophenyl) ether, hexabromobenzene, and 2-ethylhexyl 2,3,4,5-tetrabromobenzoate) in air. The methodology is based on low volume active air sampling of gaseous and particulate air fractions on mixed-bed (polydimethylsiloxane (PDMS)/Tenax TA) sorption tubes. The optimized method provides recoveries >88%; a limit of detection in the range of 6-25 pg m(-3) for PBDEs, 6-171 pg m(-3) for PFRs, and 7-41 pg m(-3) for NBFRs; a linearity greater than 0.996; and a repeatability of less than 10% for all studied compounds. The optimized method was compared with a standard method using active air sampling on XAD-2 sorbent material, followed by liquid extraction. On the one hand, the PDMS/Tenax TA method shows comparable results at longer sampling time conditions (e.g., indoor air sampling, personal air sampling). On the other hand, at shorter sampling time conditions (e.g., sampling from emission test chambers), the optimized method detects up to three times higher concentrations and identifies more flame retardant compounds compared to the standard method based on XAD-2 loading.

  14. Influences of sampling effort on detected patterns and structuring processes of a Neotropical plant-hummingbird network.

    PubMed

    Vizentin-Bugoni, Jeferson; Maruyama, Pietro K; Debastiani, Vanderlei J; Duarte, L da S; Dalsgaard, Bo; Sazima, Marlies

    2016-01-01

    Virtually all empirical ecological interaction networks to some extent suffer from undersampling. However, how limitations imposed by sampling incompleteness affect our understanding of ecological networks is still poorly explored, which may hinder further advances in the field. Here, we use a plant-hummingbird network with unprecedented sampling effort (2716 h of focal observations) from the Atlantic Rainforest in Brazil, to investigate how sampling effort affects the description of network structure (i.e. widely used network metrics) and the relative importance of distinct processes (i.e. species abundances vs. traits) in determining the frequency of pairwise interactions. By dividing the network into time slices representing a gradient of sampling effort, we show that quantitative metrics, such as interaction evenness, specialization (H2 '), weighted nestedness (wNODF) and modularity (Q; QuanBiMo algorithm) were less biased by sampling incompleteness than binary metrics. Furthermore, the significance of some network metrics changed along the sampling effort gradient. Nevertheless, the higher importance of traits in structuring the network was apparent even with small sampling effort. Our results (i) warn against using very poorly sampled networks as this may bias our understanding of networks, both their patterns and structuring processes, (ii) encourage the use of quantitative metrics little influenced by sampling when performing spatio-temporal comparisons and (iii) indicate that in networks strongly constrained by species traits, such as plant-hummingbird networks, even small sampling is sufficient to detect their relative importance for the frequencies of interactions. Finally, we argue that similar effects of sampling are expected for other highly specialized subnetworks.

  15. Probabilistic Inference in General Graphical Models through Sampling in Stochastic Networks of Spiking Neurons

    PubMed Central

    Pecevski, Dejan; Buesing, Lars; Maass, Wolfgang

    2011-01-01

    An important open problem of computational neuroscience is the generic organization of computations in networks of neurons in the brain. We show here through rigorous theoretical analysis that inherent stochastic features of spiking neurons, in combination with simple nonlinear computational operations in specific network motifs and dendritic arbors, enable networks of spiking neurons to carry out probabilistic inference through sampling in general graphical models. In particular, it enables them to carry out probabilistic inference in Bayesian networks with converging arrows (“explaining away”) and with undirected loops, that occur in many real-world tasks. Ubiquitous stochastic features of networks of spiking neurons, such as trial-to-trial variability and spontaneous activity, are necessary ingredients of the underlying computational organization. We demonstrate through computer simulations that this approach can be scaled up to neural emulations of probabilistic inference in fairly large graphical models, yielding some of the most complex computations that have been carried out so far in networks of spiking neurons. PMID:22219717

  16. CALS Test Network Sacramento Air Logistics Center. CALS/EDI Transfer Test Number 2, Quick Short Test Report.

    DTIC Science & Technology

    2007-11-02

    McClellan AFB , CA. The test required CALS data (MIL-R-28002A Raster) to be sent in an EDI (Electronic Data Interchange) envelope over a commercial VAN...Livermore National Laboratory EC/EDI (Electronic Commerce Through Electronic Data Interchange) Project, and the Sacramento Air Logistics Center (SM-ALC...Value Added Network). CALS Test Network Sacramento Air Logistics Center CALS/EDI Data Transfer Test Number 2 Quick Short Test Report.

  17. Comparison of air dispersion modeling results with ambient air sampling data: A case study at Tacoma Landfill, a National Priorities List Site

    SciTech Connect

    Griffin, L.R. ); Rutherford, T.L. )

    1994-08-01

    Air dispersion modeling, ambient air sampling, and emissions testing of landfill sources have been performed to evaluate the effects of remedial activities on ambient air surrounding the Tacoma Landfill. In 1983, the Tacoma Landfill was placed on the National Priorities List (NPL) as part of the Commencement Bay/South Tacoma Channel Superfund site. Remedial activities completed, or near completion, at the 190 acre (768,903 m[sup 2]) Tacoma Landfill include a groundwater extraction system and air stripping units used to remove volatile organic compounds (VOCs) from groundwater, landfill gas extraction and flare system to control gas migration from the landfill, landfill liner and leachate collection system for an active section of the landfill, and a landfill cap that covers the inactive portions of the landfill. Dispersion modeling was performed with measured stack emission data using Industrial Source Complex (ISC) to determine the groundlevel concentrations of VOCs from the air stripper, flares, and active portion of the landfill for comparison with the measured ambient air data collected during 1992. 9 refs., 3 figs., 6 tabs.

  18. Tick-, mosquito-, and rodent-borne parasite sampling designs for the National Ecological Observatory Network

    USGS Publications Warehouse

    Springer, Yuri P; Hoekman, David; Johnson, Pieter TJ; Duffy, Paul A; Hufft, Rebecca A.; Barnett, David T.; Allan, Brian F.; Amman, Brian R; Barker, Christopher M; Barrera, Roberto; Beard, Charles B; Beati, Lorenza; Begon, Mike; Blackmore, Mark S; Bradshaw, William E; Brisson, Dustin; Calisher, Charles H.; Childs, James E; Diuk-Wasser, Maria A; Douglass, Richard J; Eisen, Rebecca J; Foley, Desmond H; Foley, Janet E; Gaff, Holly D; Gardner, Scott L; Ginsberg, Howard; Glass, Gregory E; Hamer, Sarah A; Hayden, Mary H; Hjelle, Brian; Holzapfel, Christina M; Juliano, Steven A.; Kramer, Laura D.; Kuenzi, Amy J.; LaDeau, Shannon L.; Livdahl, Todd P.; Mills, James N.; Moore, Chester G.; Morand, Serge; Nasci, Roger S.; Ogden, Nicholas H.; Ostfeld, Richard S.; Parmenter, Robert R.; Piesman, Joseph; Reisen, William K.; Savage, Harry M.; Sonenshine, Daniel E.; Swei, Andrea; Yabsley, Michael J.

    2016-01-01

    Parasites and pathogens are increasingly recognized as significant drivers of ecological and evolutionary change in natural ecosystems. Concurrently, transmission of infectious agents among human, livestock, and wildlife populations represents a growing threat to veterinary and human health. In light of these trends and the scarcity of long-term time series data on infection rates among vectors and reservoirs, the National Ecological Observatory Network (NEON) will collect measurements and samples of a suite of tick-, mosquito-, and rodent-borne parasites through a continental-scale surveillance program. Here, we describe the sampling designs for these efforts, highlighting sampling priorities, field and analytical methods, and the data as well as archived samples to be made available to the research community. Insights generated by this sampling will advance current understanding of and ability to predict changes in infection and disease dynamics in novel, interdisciplinary, and collaborative ways.

  19. Epidemic risk from friendship network data: an equivalence with a non-uniform sampling of contact networks.

    PubMed

    Fournet, Julie; Barrat, Alain

    2016-04-15

    Contacts between individuals play an important role in determining how infectious diseases spread. Various methods to gather data on such contacts co-exist, from surveys to wearable sensors. Comparisons of data obtained by different methods in the same context are however scarce, in particular with respect to their use in data-driven models of spreading processes. Here, we use a combined data set describing contacts registered by sensors and friendship relations in the same population to address this issue in a case study. We investigate if the use of the friendship network is equivalent to a sampling procedure performed on the sensor contact network with respect to the outcome of simulations of spreading processes: such an equivalence might indeed give hints on ways to compensate for the incompleteness of contact data deduced from surveys. We show that this is indeed the case for these data, for a specifically designed sampling procedure, in which respondents report their neighbors with a probability depending on their contact time. We study the impact of this specific sampling procedure on several data sets, discuss limitations of our approach and its possible applications in the use of data sets of various origins in data-driven simulations of epidemic processes.

  20. Epidemic risk from friendship network data: an equivalence with a non-uniform sampling of contact networks

    NASA Astrophysics Data System (ADS)

    Fournet, Julie; Barrat, Alain

    2016-04-01

    Contacts between individuals play an important role in determining how infectious diseases spread. Various methods to gather data on such contacts co-exist, from surveys to wearable sensors. Comparisons of data obtained by different methods in the same context are however scarce, in particular with respect to their use in data-driven models of spreading processes. Here, we use a combined data set describing contacts registered by sensors and friendship relations in the same population to address this issue in a case study. We investigate if the use of the friendship network is equivalent to a sampling procedure performed on the sensor contact network with respect to the outcome of simulations of spreading processes: such an equivalence might indeed give hints on ways to compensate for the incompleteness of contact data deduced from surveys. We show that this is indeed the case for these data, for a specifically designed sampling procedure, in which respondents report their neighbors with a probability depending on their contact time. We study the impact of this specific sampling procedure on several data sets, discuss limitations of our approach and its possible applications in the use of data sets of various origins in data-driven simulations of epidemic processes.

  1. A novel Whole Air Sample Profiler (WASP) for the quantification of volatile organic compounds in the boundary layer

    SciTech Connect

    Mak, J. E.; Su, L.; Guenther, Alex B.; Karl, Thomas G.

    2013-10-16

    The emission and fate of reactive VOCs is of inherent interest to those studying chemical biosphere-atmosphere interactions. In-canopy VOC observations are obtainable using tower-based samplers, but the lack of suitable sampling systems for the full boundary 5 layer has limited the data characterizing the vertical structure of such gases above the canopy height and still in the boundary layer. This is the important region where many reactive VOCs are oxidized or otherwise removed. Here we describe an airborne sampling system designed to collect a vertical profile of air into a 3/800 OD tube 150m in length. The inlet ram air pressure is used to flow sampled air through the 10 tube, which results in a varying flow rate based on aircraft speed and altitude. Since aircraft velocity decreases during ascent, it is necessary to account for the variable flow rate into the tube. This is accomplished using a reference gas that is pulsed into the air stream so that the precise altitude of the collected air can be reconstructed post-collection. The pulsed injections are also used to determine any significant effect 15 from diffusion/mixing within the sampling tube, either during collection or subsequent extraction for gas analysis. This system has been successfully deployed, and we show some measured vertical profiles of isoprene and its oxidation products methacrolein and methyl vinyl ketone from a mixed canopy near Columbia, Missouri.

  2. Day and night variation in chemical composition and toxicological responses of size segregated urban air PM samples in a high air pollution situation

    NASA Astrophysics Data System (ADS)

    Jalava, P. I.; Wang, Q.; Kuuspalo, K.; Ruusunen, J.; Hao, L.; Fang, D.; Väisänen, O.; Ruuskanen, A.; Sippula, O.; Happo, M. S.; Uski, O.; Kasurinen, S.; Torvela, T.; Koponen, H.; Lehtinen, K. E. J.; Komppula, M.; Gu, C.; Jokiniemi, J.; Hirvonen, M.-R.

    2015-11-01

    Urban air particulate pollution is a known cause for adverse human health effects worldwide. China has encountered air quality problems in recent years due to rapid industrialization. Toxicological effects induced by particulate air pollution vary with particle sizes and season. However, it is not known how distinctively different photochemical activity and different emission sources during the day and the night affect the chemical composition of the PM size ranges and subsequently how it is reflected to the toxicological properties of the PM exposures. The particulate matter (PM) samples were collected in four different size ranges (PM10-2.5; PM2.5-1; PM1-0.2 and PM0.2) with a high volume cascade impactor. The PM samples were extracted with methanol, dried and thereafter used in the chemical and toxicological analyses. RAW264.7 macrophages were exposed to the particulate samples in four different doses for 24 h. Cytotoxicity, inflammatory parameters, cell cycle and genotoxicity were measured after exposure of the cells to particulate samples. Particles were characterized for their chemical composition, including ions, element and PAH compounds, and transmission electron microscopy (TEM) was used to take images of the PM samples. Chemical composition and the induced toxicological responses of the size segregated PM samples showed considerable size dependent differences as well as day to night variation. The PM10-2.5 and the PM0.2 samples had the highest inflammatory potency among the size ranges. Instead, almost all the PM samples were equally cytotoxic and only minor differences were seen in genotoxicity and cell cycle effects. Overall, the PM0.2 samples had the highest toxic potential among the different size ranges in many parameters. PAH compounds in the samples and were generally more abundant during the night than the day, indicating possible photo-oxidation of the PAH compounds due to solar radiation. This was reflected to different toxicity in the PM

  3. Mapping real-time air pollution health risk for environmental management: Combining mobile and stationary air pollution monitoring with neural network models.

    PubMed

    Adams, Matthew D; Kanaroglou, Pavlos S

    2016-03-01

    Air pollution poses health concerns at the global scale. The challenge of managing air pollution is significant because of the many air pollutants, insufficient funds for monitoring and abatement programs, and political and social challenges in defining policy to limit emissions. Some governments provide citizens with air pollution health risk information to allow them to limit their exposure. However, many regions still have insufficient air pollution monitoring networks to provide real-time mapping. Where available, these risk mapping systems either provide absolute concentration data or the concentrations are used to derive an Air Quality Index, which provides the air pollution risk for a mix of air pollutants with a single value. When risk information is presented as a single value for an entire region it does not inform on the spatial variation within the region. Without an understanding of the local variation residents can only make a partially informed decision when choosing daily activities. The single value is typically provided because of a limited number of active monitoring units in the area. In our work, we overcome this issue by leveraging mobile air pollution monitoring techniques, meteorological information and land use information to map real-time air pollution health risks. We propose an approach that can provide improved health risk information to the public by applying neural network models within a framework that is inspired by land use regression. Mobile air pollution monitoring campaigns were conducted across Hamilton from 2005 to 2013. These mobile air pollution data were modelled with a number of predictor variables that included information on the surrounding land use characteristics, the meteorological conditions, air pollution concentrations from fixed location monitors, and traffic information during the time of collection. Fine particulate matter and nitrogen dioxide were both modelled. During the model fitting process we reserved

  4. Minimization of sample volume with air-segmented sample injection and the simultaneous determination of trace elements by ICP-MS.

    PubMed

    Noguchi, Osamu; Oshima, Mitsuko; Motomizu, Shoji

    2008-05-01

    The application of inductively coupled plasma mass spectrometry (ICP-MS) to forensic chemistry was studied. The developed method, air-segmented sample injection (ASSI) coupled with ICP-MS, allowed the determination of about 25 elements at the sub-ppb level with only 0.2 ml of a sample solution. The optimum sample flow rate was found to be 0.4 ml min(-1), along with a sample suction time of 30 s. The proposed method was validated by determining trace elements in river-water certified reference material (SLRS-4) issued by National Research Council Canada. The analytical results of the proposed method were in good agreement with the certified values. This method was successfully applied to a human hair sample, the volume of which was 3 ml.

  5. Suitability of air sampling locations downstream of bends and static mixing elements.

    PubMed

    McFarland, A R; Gupta, R; Anand, N K

    1999-12-01

    The revised standard for sampling effluent air from stacks and ducts of the nuclear industry places limits on the non-uniformity of velocity and contaminant profiles at the sampling location; namely, the coefficients of variation must not exceed 20% over an area that encompasses at least the center 2/3 of the cross sectional area. Tests were conducted to characterize the degree of mixing at downstream locations as affected by several types of flow disturbances, including 90 degree elbows and commercial static mixing devices. Flow straighteners were incorporated into the ducting upstream of the mixer to be tested to simulate the dampening of flow turbulence that might occur because of upstream HEPA filters. The coefficients of variation of velocity and tracer gas concentration measured in a straight tube at a distance of 3 diameters downstream from a 90 degree elbow were 17% and 69%, respectively. The mixing is impacted by the upstream flow turbulence. Without a flow straightener, the tracer gas concentration coefficient of variation was reduced to 33% at the 3-diameter location. The use of static mixing elements can greatly enhance the mixing process. A ring placed just downstream of a 90 degree elbow, which blocks the outer 56% of the cross sectional area, results in a coefficient of variation of 19% for tracer gas concentration at the 3-diameter location. Pressure loss across the elbow with the ring is about nine times that of the basic elbow. One of the commercially available static mixers provides coefficients of variation that are less than 10% for both velocity and tracer gas concentration at 4 diameters downstream from the mixer with a pressure loss that is only about 3.5 times as large as that of a 90 degree elbow.

  6. Evaluating network analysis and agent based modeling for investigating the stability of commercial air carrier schedules

    NASA Astrophysics Data System (ADS)

    Conway, Sheila Ruth

    For a number of years, the United States Federal Government has been formulating the Next Generation Air Transportation System plans for National Airspace System improvement. These improvements attempt to address air transportation holistically, but often address individual improvements in one arena such as ground or in-flight equipment. In fact, air transportation system designers have had only limited success using traditional Operations Research and parametric modeling approaches in their analyses of innovative operations. They need a systemic methodology for modeling of safety-critical infrastructure that is comprehensive, objective, and sufficiently concrete, yet simple enough to be deployed with reasonable investment. The methodology must also be amenable to quantitative analysis so issues of system safety and stability can be rigorously addressed. The literature suggests that both agent-based models and network analysis techniques may be useful for complex system development and analysis. The purpose of this research is to evaluate these two techniques as applied to analysis of commercial air carrier schedule (route) stability in daily operations, an important component of air transportation. Airline-like routing strategies are used to educe essential elements of applying the method. Two main models are developed, one investigating the network properties of the route structure, the other an Agent-based approach. The two methods are used to predict system properties at a macro-level. These findings are compared to observed route network performance measured by adherence to a schedule to provide validation of the results. Those interested in complex system modeling are provided some indication as to when either or both of the techniques would be applicable. For aviation policy makers, the results point to a toolset capable of providing insight into the system behavior during the formative phases of development and transformation with relatively low investment

  7. Ice nucleation active particles in continental air samples over Mainz, Germany

    NASA Astrophysics Data System (ADS)

    Pummer, Bernhard G.; Pöschl, Ulrich; Fröhlich-Nowoisky, Janine

    2016-04-01

    Aerosol particles are of central importance for atmospheric chemistry and physics, climate and public health. Some of these particles possess ice nucleation activity (INA), which is highly relevant for cloud formation and precipitation. In 2010, air filter samples were collected with a high-volume filter sampler separating fine and coarse particles (aerodynamic cut-off diameter 3 μm) in Mainz, Germany. In this study, the INA of the atmospheric particles deposited on these filters was determined. Therefore,they were extracted with ultrapure water, which was then measured in a droplet freezing assay, as described in Fröhlich-Nowoisky et al. (2015). The determined concentration of ice nucleators (INs) was between 0.3 and 2per m³ at 266 K, and between5 and 75 per m³ at 260 K. The INs were further characterized by different treatments, like heating (308 K, 371 K), filtration (0.1 μm, 300 kDa), and digestion with papain (10 mg/ml). We further investigated, which atmospheric conditions (e.g. weather) and distinguished events (e.g. dust storms, volcanic eruptions, and pollen peaks) influenced the number and nature of these INs. Fröhlich-Nowoisky, J., Hill, T. C. J., Pummer, B. G., Yordanova, P., Franc, G. D., and Pöschl, U.: Ice nucleation activity in the widespread soil fungus Mortierella alpina, Biogeosci., 12, 1057-1071, doi:10.5194/bg-12-1057-2015, 2015.

  8. Comparison of halocarbon measurements in an atmospheric dry whole air sample

    PubMed Central

    Hall, Bradley D.; Harth, Christina M.; Kim, Jin Seog; Lee, Jeongsoon; Montzka, Stephen A.; Mühle, Jens; Reimann, Stefan; Vollmer, Martin K.; Weiss, Ray F.

    2015-01-01

    The growing awareness of climate change/global warming, and continuing concerns regarding stratospheric ozone depletion, will require continued measurements and standards for many compounds, in particular halocarbons that are linked to these issues. In order to track atmospheric mole fractions and assess the impact of policy on emission rates, it is necessary to demonstrate measurement equivalence at the highest levels of accuracy for assigned values of standards. Precise measurements of these species aid in determining small changes in their atmospheric abundance. A common source of standards/scales and/or well-documented agreement of different scales used to calibrate the measurement instrumentation are key to understanding many sets of data reported by researchers. This report describes the results of a comparison study among National Metrology Institutes and atmospheric research laboratories for the chlorofluorocarbons (CFCs) dichlorodifluoromethane (CFC-12), trichlorofluoromethane (CFC-11), and 1,1,2-trichlorotrifluoroethane (CFC-113); the hydrochlorofluorocarbons (HCFCs) chlorodifluoromethane (HCFC-22) and 1-chloro-1,1-difluoroethane (HCFC-142b); and the hydrofluorocarbon (HFC) 1,1,1,2-tetrafluoroethane (HFC-134a), all in a dried whole air sample. The objective of this study is to compare calibration standards/scales and the measurement capabilities of the participants for these halocarbons at trace atmospheric levels. The results of this study show agreement among four independent calibration scales to better than 2.5% in almost all cases, with many of the reported agreements being better than 1.0%. PMID:26753167

  9. Air-dropped sensor network for real-time high-fidelity volcano monitoring

    USGS Publications Warehouse

    Song, W.-Z.; Huang, R.; Xu, M.; Ma, A.; Shirazi, B.; LaHusen, R.

    2009-01-01

    This paper presents the design and deployment experience of an air-dropped wireless sensor network for volcano hazard monitoring. The deployment of five stations into the rugged crater of Mount St. Helens only took one hour with a helicopter. The stations communicate with each other through an amplified 802.15.4 radio and establish a self-forming and self-healing multi-hop wireless network. The distance between stations is up to 2 km. Each sensor station collects and delivers real-time continuous seismic, infrasonic, lightning, GPS raw data to a gateway. The main contribution of this paper is the design and evaluation of a robust sensor network to replace data loggers and provide real-time long-term volcano monitoring. The system supports UTC-time synchronized data acquisition with 1ms accuracy, and is online configurable. It has been tested in the lab environment, the outdoor campus and the volcano crater. Despite the heavy rain, snow, and ice as well as gusts exceeding 120 miles per hour, the sensor network has achieved a remarkable packet delivery ratio above 99% with an overall system uptime of about 93.8% over the 1.5 months evaluation period after deployment. Our initial deployment experiences with the system have alleviated the doubts of domain scientists and prove to them that a low-cost sensor network system can support real-time monitoring in extremely harsh environments. Copyright 2009 ACM.

  10. Seluge++: A Secure Over-the-Air Programming Scheme in Wireless Sensor Networks

    PubMed Central

    Doroodgar, Farzan; Razzaque, Mohammad Abdur; Isnin, Ismail Fauzi

    2014-01-01

    Over-the-air dissemination of code updates in wireless sensor networks have been researchers' point of interest in the last few years, and, more importantly, security challenges toward the remote propagation of code updating have occupied the majority of efforts in this context. Many security models have been proposed to establish a balance between the energy consumption and security strength, having their concentration on the constrained nature of wireless sensor network (WSN) nodes. For authentication purposes, most of them have used a Merkle hash tree to avoid using multiple public cryptography operations. These models mostly have assumed an environment in which security has to be at a standard level. Therefore, they have not investigated the tree structure for mission-critical situations in which security has to be at the maximum possible level (e.g., military applications, healthcare). Considering this, we investigate existing security models used in over-the-air dissemination of code updates for possible vulnerabilities, and then, we provide a set of countermeasures, correspondingly named Security Model Requirements. Based on the investigation, we concentrate on Seluge, one of the existing over-the-air programming schemes, and we propose an improved version of it, named Seluge++, which complies with the Security Model Requirements and replaces the use of the inefficient Merkle tree with a novel method. Analytical and simulation results show the improvements in Seluge++ compared to Seluge. PMID:24618781

  11. What Big Data tells: Sampling the social network by communication channels

    NASA Astrophysics Data System (ADS)

    Török, János; Murase, Yohsuke; Jo, Hang-Hyun; Kertész, János; Kaski, Kimmo

    2016-11-01

    Big Data has become the primary source of understanding the structure and dynamics of the society at large scale. The network of social interactions can be considered as a multiplex, where each layer corresponds to one communication channel and the aggregate of all of them constitutes the entire social network. However, usually one has information only about one of the channels or even a part of it, which should be considered as a subset or sample of the whole. Here we introduce a model based on a natural bilateral communication channel selection mechanism, which for one channel leads to consistent changes in the network properties. For example, while it is expected that the degree distribution of the whole social network has a maximum at a value larger than one, we get a monotonically decreasing distribution as observed in empirical studies of single-channel data. We also find that assortativity may occur or get strengthened due to the sampling method. We analyze the far-reaching consequences of our findings.

  12. Discretisation and control of polytopic systems with uncertain sampling rates and network-induced delays

    NASA Astrophysics Data System (ADS)

    Braga, Márcio F.; Morais, Cecília F.; Tognetti, Eduardo S.; Oliveira, Ricardo C. L. F.; Peres, Pedro L. D.

    2014-11-01

    This paper investigates the problems of uncertain sampling rate discretisation and the networked control of uncertain time-invariant continuous-time linear systems in polytopic domains. The sampling period is assumed to be unknown but belonging to a given interval. To avoid the difficulty of dealing with the exponential of uncertain matrices, a discrete-time model is obtained by applying a Taylor series expansion of degree ℓ to the original system. The resulting discrete-time model is composed of homogeneous polynomial matrices with parameters lying in the Cartesian product of simplexes, called a multi-simplex, plus an additive norm-bounded term representing the discretisation residual error. The original continuous-time system is controlled through a communication network that introduces a time delay in the process. Linear matrix inequality relaxations that include a scalar parameter search are proposed for the design of a digital robust state feedback controller that guarantees the closed-loop stability of the networked control system. Numerical experiments are presented to illustrate the versatility of the proposed method, which can be applied to a more general class of networked control problems than the existing approaches in the literature.

  13. A holistic approach for optimal design of air quality monitoring network expansion in an urban area

    NASA Astrophysics Data System (ADS)

    Mofarrah, Abdullah; Husain, Tahir

    2010-01-01

    This paper presents an objective methodology for determining the optimum number of ambient air quality stations in a monitoring network. The methodology integrates the multiple-criteria method with the spatial correlation technique. The pollutant concentration and population exposure data are used in this methodology in different ways. In the first stage, the Fuzzy Analytic Hierarchy Process (FAHP) with triangular fuzzy numbers (TFNs) is used to identify the most desirable monitoring locations. The network configuration is then determined on the basis of the concept of sphere of influences (SOIs). The SOIs are dictated by a predetermined cutoff value ( rc) in the spatial correlation coefficients ( r) between the pollutant concentrations at the monitoring stations identified from first step and the corresponding concentrations at neighboring locations in the region. Finally, the optimal station locations are ranked by using combined utility scores gained from the first and second steps. The expansion of air quality monitoring network of Riyadh city in Saudi Arabia is used as a case study to demonstrate the proposed methodology.

  14. Comparison of Air Impaction and Electrostatic Dust Collector Sampling Methods to Assess Airborne Fungal Contamination in Public Buildings.

    PubMed

    Normand, Anne-Cécile; Ranque, Stéphane; Cassagne, Carole; Gaudart, Jean; Sallah, Kankoé; Charpin, Denis-André; Piarroux, Renaud

    2016-03-01

    Many ailments can be linked to exposure to indoor airborne fungus. However, obtaining a precise measurement of airborne fungal levels is complicated partly due to indoor air fluctuations and non-standardized techniques. Electrostatic dust collector (EDC) sampling devices have been used to measure a wide range of airborne analytes, including endotoxins, allergens, β-glucans, and microbial DNA in various indoor environments. In contrast, viable mold contamination has only been assessed in highly contaminated environments such as farms and archive buildings. This study aimed to assess the use of EDCs, compared with repeated air-impactor measurements, to assess airborne viable fungal flora in moderately contaminated indoor environments. Indoor airborne fungal flora was cultured from EDCs and daily air-impaction samples collected in an office building and a daycare center. The quantitative fungal measurements obtained using a single EDC significantly correlated with the cumulative measurement of nine daily air impactions. Both methods enabled the assessment of fungal exposure, although a few differences were observed between the detected fungal species and the relative quantity of each species. EDCs were also used over a 32-month period to monitor indoor airborne fungal flora in a hospital office building, which enabled us to assess the impact of outdoor events (e.g. ground excavations) on the fungal flora levels on the indoor environment. In conclusion, EDC-based measurements provided a relatively accurate profile of the viable airborne flora present during a sampling period. In particular, EDCs provided a more representative assessment of fungal levels compared with single air-impactor sampling. The EDC technique is also simpler than performing repetitive air-impaction measures over the course of several consecutive days. EDC is a versatile tool for collecting airborne samples and was efficient for measuring mold levels in indoor environments.

  15. Estimating sampling biases and measurement uncertainties of AIRS/AMSU-A temperature and water vapor observations using MERRA reanalysis

    NASA Astrophysics Data System (ADS)

    Hearty, Thomas J.; Savtchenko, Andrey; Tian, Baijun; Fetzer, Eric; Yung, Yuk L.; Theobald, Michael; Vollmer, Bruce; Fishbein, Evan; Won, Young-In

    2014-03-01

    We use MERRA (Modern Era Retrospective-Analysis for Research Applications) temperature and water vapor data to estimate the sampling biases of climatologies derived from the AIRS/AMSU-A (Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit-A) suite of instruments. We separate the total sampling bias into temporal and instrumental components. The temporal component is caused by the AIRS/AMSU-A orbit and swath that are not able to sample all of time and space. The instrumental component is caused by scenes that prevent successful retrievals. The temporal sampling biases are generally smaller than the instrumental sampling biases except in regions with large diurnal variations, such as the boundary layer, where the temporal sampling biases of temperature can be ± 2 K and water vapor can be 10% wet. The instrumental sampling biases are the main contributor to the total sampling biases and are mainly caused by clouds. They are up to 2 K cold and > 30% dry over midlatitude storm tracks and tropical deep convective cloudy regions and up to 20% wet over stratus regions. However, other factors such as surface emissivity and temperature can also influence the instrumental sampling bias over deserts where the biases can be up to 1 K cold and 10% wet. Some instrumental sampling biases can vary seasonally and/or diurnally. We also estimate the combined measurement uncertainties of temperature and water vapor from AIRS/AMSU-A and MERRA by comparing similarly sampled climatologies from both data sets. The measurement differences are often larger than the sampling biases and have longitudinal variations.

  16. Estimating Sampling Biases and Measurement Uncertainties of AIRS-AMSU-A Temperature and Water Vapor Observations Using MERRA Reanalysis

    NASA Technical Reports Server (NTRS)

    Hearty, Thomas J.; Savtchenko, Andrey K.; Tian, Baijun; Fetzer, Eric; Yung, Yuk L.; Theobald, Michael; Vollmer, Bruce; Fishbein, Evan; Won, Young-In

    2014-01-01

    We use MERRA (Modern Era Retrospective-Analysis for Research Applications) temperature and water vapor data to estimate the sampling biases of climatologies derived from the AIRS/AMSU-A (Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit-A) suite of instruments. We separate the total sampling bias into temporal and instrumental components. The temporal component is caused by the AIRS/AMSU-A orbit and swath that are not able to sample all of time and space. The instrumental component is caused by scenes that prevent successful retrievals. The temporal sampling biases are generally smaller than the instrumental sampling biases except in regions with large diurnal variations, such as the boundary layer, where the temporal sampling biases of temperature can be +/- 2 K and water vapor can be 10% wet. The instrumental sampling biases are the main contributor to the total sampling biases and are mainly caused by clouds. They are up to 2 K cold and greater than 30% dry over mid-latitude storm tracks and tropical deep convective cloudy regions and up to 20% wet over stratus regions. However, other factors such as surface emissivity and temperature can also influence the instrumental sampling bias over deserts where the biases can be up to 1 K cold and 10% wet. Some instrumental sampling biases can vary seasonally and/or diurnally. We also estimate the combined measurement uncertainties of temperature and water vapor from AIRS/AMSU-A and MERRA by comparing similarly sampled climatologies from both data sets. The measurement differences are often larger than the sampling biases and have longitudinal variations.

  17. The Air Force Academy’s Falcon Telescope Network: An Educational and Research Network for K-12 and Higher Education

    NASA Astrophysics Data System (ADS)

    Chun, Francis; Tippets, Roger; Della-Rose, Devin J.; Polsgrove, Daniel; Gresham, Kimberlee; Barnaby, David A.

    2015-01-01

    The Falcon Telescope Network (FTN) is a global network of small aperture telescopes developed by the Center for Space Situational Awareness Research in the Department of Physics at the United States Air Force Academy (USAFA). Consisting of commercially available equipment, the FTN is a collaborative effort between USAFA and other educational institutions ranging from two- and four-year colleges to major research universities. USAFA provides the equipment (e.g. telescope, mount, camera, filter wheel, dome, weather station, computers and storage devices) while the educational partners provide the building and infrastructure to support an observatory. The user base includes USAFA along with K-12 and higher education faculty and students. The diversity of the users implies a wide variety of observing interests, and thus the FTN collects images on diverse objects, including satellites, galactic and extragalactic objects, and objects popular for education and public outreach. The raw imagery, all in the public domain, will be accessible to FTN partners and will be archived at USAFA. USAFA cadets use the FTN to continue a tradition of satellite characterization and astronomical research; this tradition is the model used for designing the network to serve undergraduate research needs. Additionally, cadets have led the development of the FTN by investigating observation priority schemes and conducting a 'day-in-the-life' study of the FTN in regards to satellite observations. With respect to K-12 outreach, cadets have provided feedback to K-12 students and teachers through evaluation of first-light proposals. In this paper, we present the current status of the network and results from student participation in the project.

  18. US EPA Base Study Standard Operating Procedure for Sampling and Characterization of Viable and Non-Viable Bioaerosols in Indoor Air

    EPA Pesticide Factsheets

    The objective of the procedure is to collect a representative sample concentration of total airborne fungal spores (viable and non-viable) that may be present in indoor air and in the outdoor air supplied to the space tested.

  19. On Stabilization of Quantized Sampled-Data Neural-Network-Based Control Systems.

    PubMed

    Wang, Yueying; Shen, Hao; Duan, Dengping

    2016-06-28

    This paper investigates the problem of stabilization of sampled-data neural-network-based systems with state quantization. Different with previous works, the communication limitation of state quantization is considered for the first time. More specifically, it is assumed that the sampled state measurements from sensor to the controller are quantized via a quantizer. To reduce conservativeness, a novel piecewise Lyapunov-Krasovskii functional (LKF) is constructed by introducing a line-integral type Lyapunov function and some useful terms that take full advantage of the available information about the actual sampling pattern. Based on the new LKF, much less conservative stabilization conditions are derived to obtain the maximal sampling period and the minimal guaranteed cost control performance. The desired quantized sampled-data three-layer fully connected feedforward neural-network-based controllers are designed by a linear matrix inequality approach. A search algorithm is given to find the optimal values of tuning parameters. The effectiveness and advantage of proposed method are demonstrated by the numerical simulation of an inverted pendulum.

  20. Data splitting for artificial neural networks using SOM-based stratified sampling.

    PubMed

    May, R J; Maier, H R; Dandy, G C

    2010-03-01

    Data splitting is an important consideration during artificial neural network (ANN) development where hold-out cross-validation is commonly employed to ensure generalization. Even for a moderate sample size, the sampling methodology used for data splitting can have a significant effect on the quality of the subsets used for training, testing and validating an ANN. Poor data splitting can result in inaccurate and highly variable model performance; however, the choice of sampling methodology is rarely given due consideration by ANN modellers. Increased confidence in the sampling is of paramount importance, since the hold-out sampling is generally performed only once during ANN development. This paper considers the variability in the quality of subsets that are obtained using different data splitting approaches. A novel approach to stratified sampling, based on Neyman sampling of the self-organizing map (SOM), is developed, with several guidelines identified for setting the SOM size and sample allocation in order to minimize the bias and variance in the datasets. Using an example ANN function approximation task, the SOM-based approach is evaluated in comparison to random sampling, DUPLEX, systematic stratified sampling, and trial-and-error sampling to minimize the statistical differences between data sets. Of these approaches, DUPLEX is found to provide benchmark performance with good model performance, with no variability. The results show that the SOM-based approach also reliably generates high-quality samples and can therefore be used with greater confidence than other approaches, especially in the case of non-uniform datasets, with the benefit of scalability to perform data splitting on large datasets.

  1. A passive sampling-based analytical strategy for the determination of volatile organic compounds in the air of working areas.

    PubMed

    Ly-Verdú, Saray; Esteve-Turrillas, Francesc A; Pastor, Agustín; de la Guardia, Miguel

    2010-09-16

    An analytical methodology based on the use of a polyethylene layflat tube filled with activated carbon and Florisil (ACFL-VERAM) was employed for the passive sampling of volatile organic compounds (VOCs) in the air of working areas of packing industries. VOCs amount in the ACFL-VERAM sampler was directly determined through head-space-gas chromatography-mass spectrometry (HS-GC-MS) allowing a direct determination in only 20 min without the need of any previous treatment. Uptake parameters, like sampling rate (R(S)) and sampler-air partition coefficient (K(SA)), were determined for every studied VOC from adsorption isotherm data. Additionally, experimental equations have been proposed to predict R(S) and K(SA) from the octanol-air partition coefficients reported in the literature. The proposed methodology reaches method detection levels from 0.007 to 0.2 mg m(-3) for the studied VOCs.

  2. Comparison of Lichen, Conifer Needles, Passive Air Sampling Devices, and Snowpack as Passive Sampling Media to Measure Semi-Volatile Organic Compounds in Remote Atmospheres

    PubMed Central

    SCHRLAU, JILL E.; GEISER, LINDA; HAGEMAN, KIMBERLY J.; LANDERS, DIXON H.

    2011-01-01

    A wide range of semi-volatile organic compounds (SOCs), including pesticides and polycyclic aromatic hydrocarbons (PAHs), were measured in lichen, conifer needles, snowpack and XAD-based passive air sampling devices (PASDs) collected from 19 different U.S. national parks in order to compare the magnitude and mechanism of SOC accumulation in the different passive sampling media. Lichen accumulated the highest SOC concentrations, in part because of its long (and unknown) exposure period, while PASDs accumulated the lowest concentrations. However, only the PASD SOC concentrations can be used to calculate an average atmospheric gas-phase SOC concentration because the sampling rates are known and the media is uniform. Only the lichen and snowpack SOC accumulation profiles were statistically significantly correlated (r = 0.552, p-value <0.0001) because they both accumulate SOCs present in the atmospheric particle-phase. This suggests that needles and PASDs represent a different composition of the atmosphere than lichen and snowpack and that the interpretation of atmospheric SOC composition is dependent on the type of passive sampling media used. All four passive sampling media preferentially accumulated SOCs with relatively low air-water partition coefficients, while snowpack accumulated SOCs with higher log KOA values compared to the other media. Lichen accumulated more SOCs with log KOA > 10 relative to needles and showed a greater accumulation of particle-phase PAHs. PMID:22087860

  3. Comparison of lichen, conifer needles, passive air sampling devices, and snowpack as passive sampling media to measure semi-volatile organic compounds in remote atmospheres.

    PubMed

    Schrlau, Jill E; Geiser, Linda; Hageman, Kimberly J; Landers, Dixon H; Simonich, Staci Massey

    2011-12-15

    A wide range of semivolatile organic compounds (SOCs), including pesticides and polycyclic aromatic hydrocarbons (PAHs), were measured in lichen, conifer needles, snowpack and XAD-based passive air sampling devices (PASDs) collected from 19 different U.S. national parks in order to compare the magnitude and mechanism of SOC accumulation in the different passive sampling media. Lichen accumulated the highest SOC concentrations, in part because of its long (and unknown) exposure period, whereas PASDs accumulated the lowest concentrations. However, only the PASD SOC concentrations can be used to calculate an average atmospheric gas-phase SOC concentration because the sampling rates are known and the media is uniform. Only the lichen and snowpack SOC accumulation profiles were statistically significantly correlated (r = 0.552, p-value <0.0001) because they both accumulate SOCs present in the atmospheric particle-phase. This suggests that needles and PASDs represent a different composition of the atmosphere than lichen and snowpack and that the interpretation of atmospheric SOC composition is dependent on the type of passive sampling media used. All four passive sampling media preferentially accumulated SOCs with relatively low air-water partition coefficients, while snowpack accumulated SOCs with higher log K(OA) values compared to the other media. Lichen accumulated more SOCs with log K(OA) > 10 relative to needles and showed a greater accumulation of particle-phase PAHs.

  4. The deployment of carbon monoxide wireless sensor network (CO-WSN) for ambient air monitoring.

    PubMed

    Chaiwatpongsakorn, Chaichana; Lu, Mingming; Keener, Tim C; Khang, Soon-Jai

    2014-06-16

    Wireless sensor networks are becoming increasingly important as an alternative solution for environment monitoring because they can reduce cost and complexity. Also, they can improve reliability and data availability in places where traditional monitoring methods are difficult to site. In this study, a carbon monoxide wireless sensor network (CO-WSN) was developed to measure carbon monoxide concentrations at a major traffic intersection near the University of Cincinnati main campus. The system has been deployed over two weeks during Fall 2010, and Summer 2011-2012, traffic data was also recorded by using a manual traffic counter and a video camcorder to characterize vehicles at the intersection 24 h, particularly, during the morning and evening peak hour periods. According to the field test results, the 1 hr-average CO concentrations were found to range from 0.1-1.0 ppm which is lower than the National Ambient Air Quality Standards (NAAQS) 35 ppm on a one-hour averaging period. During rush hour periods, the traffic volume at the intersection varied from 2,067 to 3,076 vehicles per hour with 97% being passenger vehicles. Furthermore, the traffic volume based on a 1-h average showed good correlation (R2 = 0.87) with the 1-h average CO-WSN concentrations for morning and evening peak time periods whereas CO-WSN results provided a moderate correlation (R2 = 0.42) with 24 hours traffic volume due to fluctuated changes of meteorological conditions. It is concluded that the performance and the reliability of wireless ambient air monitoring networks can be used as an alternative method for real time air monitoring.

  5. The Deployment of Carbon Monoxide Wireless Sensor Network (CO-WSN) for Ambient Air Monitoring

    PubMed Central

    Chaiwatpongsakorn, Chaichana; Lu, Mingming; Keener, Tim C.; Khang, Soon-Jai

    2014-01-01

    Wireless sensor networks are becoming increasingly important as an alternative solution for environment monitoring because they can reduce cost and complexity. Also, they can improve reliability and data availability in places where traditional monitoring methods are difficult to site. In this study, a carbon monoxide wireless sensor network (CO-WSN) was developed to measure carbon monoxide concentrations at a major traffic intersection near the University of Cincinnati main campus. The system has been deployed over two weeks during Fall 2010, and Summer 2011–2012, traffic data was also recorded by using a manual traffic counter and a video camcorder to characterize vehicles at the intersection 24 h, particularly, during the morning and evening peak hour periods. According to the field test results, the 1 hr-average CO concentrations were found to range from 0.1–1.0 ppm which is lower than the National Ambient Air Quality Standards (NAAQS) 35 ppm on a one-hour averaging period. During rush hour periods, the traffic volume at the intersection varied from 2,067 to 3,076 vehicles per hour with 97% being passenger vehicles. Furthermore, the traffic volume based on a 1-h average showed good correlation (R2 = 0.87) with the 1-h average CO-WSN concentrations for morning and evening peak time periods whereas CO-WSN results provided a moderate correlation (R2 = 0.42) with 24 hours traffic volume due to fluctuated changes of meteorological conditions. It is concluded that the performance and the reliability of wireless ambient air monitoring networks can be used as an alternative method for real time air monitoring. PMID:24937527

  6. 32 CFR 806.27 - Samples of Air Force FOIA processing documents.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... documents. (a) This section includes suggested language in paragraph format that tracks Air Force and DoD FOIA guidance. The rest of the body of letters and memorandums should comply with Air Force... section, language in parentheses is for explanatory purposes only. Do not include any of the...

  7. It's Alive!: Students Observe Air-Water Interface Samples Rich with Organisms

    ERIC Educational Resources Information Center

    Avant, Thomas

    2002-01-01

    This article describes an experiment, designed by Cindy Henk, manager of the Socolofsky Microscopy Center at Louisiana State University (LSU), that involved collecting and viewing microorganisms in the air-water interface. The experiment was participated by Leesville High School microbiology students. The students found that the air-water…

  8. Early detection of foot-and-mouth disease virus from infected cattle using a dry filter air sampling system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Foot-and-mouth disease (FMD) is a highly contagious livestock disease of high economic impact. Early detection of FMD virus (FMDV) is fundamental for rapid outbreak control. Air sampling collection has been demonstrated as a useful technique for detection of FMDV RNA in infected animals, related to ...

  9. A new software for planning the compressed air networks in mines

    SciTech Connect

    Madani, H.; Asadi, A.

    1996-12-31

    There are different formulae for calculation of pressure loss in compressed air networks, but all have some limitation (length, diameter, flowrate temperature ... ). In practice, it is not easy to evaluate these formulae and choose the most suitable one for each case. In order to overcome these difficulties, a computer program was written in the form of an M.Sc thesis, and the result is a new software which can be used for calculation of pressure loss and choosing the optimum diameter of the pipes. After entering data, computer chooses the best formula (out of 14) for each branch of the network, based on the condition, and the result is available with different confidential limits.

  10. Neural network modeling of air pollution in tunnels according to indirect measurements

    NASA Astrophysics Data System (ADS)

    Kaverzneva, T.; Lazovskaya, T.; Tarkhov, D.; Vasilyev, A.

    2016-11-01

    The article deals with the problem of providing the necessary parameters of air of the working area in dead-end tunnels in the case of ventilation systems powered off. An ill-posed initialboundary problem for the diffusion equation is used as a mathematical model for a description and analysis of mass transfer processes in the tunnel. The neural network approach is applied to construct an approximate solution (regularization) of the identification problem in the case of the approximate measurement data and the set of interval parameters of the modeled system. Two types of model measurements included binary data are considered. The direct problem solution and the inverse problem regularization for the offered neural network approach are constructed uniformly.

  11. Failure forecast of Boeing 737 bleed air system using artificial neural networks

    NASA Astrophysics Data System (ADS)

    Al-Wadiee, Waheed

    In this study, the failure rate of different types of bleed air control valves for the Boeing 737 aircraft is modeled. Two approaches are utilized to perform this work. In the first approach, Weibull model, in which different parameters are utilized and tested, is used. In the second one, a common type of the Artificial Neural Network (ANN) modeling is used. A Feed-forward back-propagation algorithm is implemented to train the network. Subsequently, the optimum number of neurons and layers that give the best result compared to the actual data are determined. Finally, the outputs from both models are compared against the actual data. The final results show a high level of accuracy of the ANN's predictions compared to the more traditional Weibull modeling. The developed verified model lends itself to applications that extend from scheduling replacements operations of these valves, to developing plans for inventory management in any aviation engines maintenance facility.

  12. Community Air Sensor Network (CAIRSENSE) project: evaluation of low-cost sensor performance in a suburban environment in the southeastern United States

    NASA Astrophysics Data System (ADS)

    Jiao, Wan; Hagler, Gayle; Williams, Ronald; Sharpe, Robert; Brown, Ryan; Garver, Daniel; Judge, Robert; Caudill, Motria; Rickard, Joshua; Davis, Michael; Weinstock, Lewis; Zimmer-Dauphinee, Susan; Buckley, Ken

    2016-11-01

    Advances in air pollution sensor technology have enabled the development of small and low-cost systems to measure outdoor air pollution. The deployment of a large number of sensors across a small geographic area would have potential benefits to supplement traditional monitoring networks with additional geographic and temporal measurement resolution, if the data quality were sufficient. To understand the capability of emerging air sensor technology, the Community Air Sensor Network (CAIRSENSE) project deployed low-cost, continuous, and commercially available air pollution sensors at a regulatory air monitoring site and as a local sensor network over a surrounding ˜ 2 km area in the southeastern United States. Collocation of sensors measuring oxides of nitrogen, ozone, carbon monoxide, sulfur dioxide, and particles revealed highly variable performance, both in terms of comparison to a reference monitor as well as the degree to which multiple identical sensors produced the same signal. Multiple ozone, nitrogen dioxide, and carbon monoxide sensors revealed low to very high correlation with a reference monitor, with Pearson sample correlation coefficient (r) ranging from 0.39 to 0.97, -0.25 to 0.76, and -0.40 to 0.82, respectively. The only sulfur dioxide sensor tested revealed no correlation (r < 0.5) with a reference monitor and erroneously high concentration values. A wide variety of particulate matter (PM) sensors were tested with variable results - some sensors had very high agreement (e.g., r = 0.99) between identical sensors but moderate agreement with a reference PM2.5 monitor (e.g., r = 0.65). For select sensors that had moderate to strong correlation with reference monitors (r > 0.5), step-wise multiple linear regression was performed to determine if ambient temperature, relative humidity (RH), or age of the sensor in number of sampling days could be used in a correction algorithm to improve the agreement. Maximum improvement in agreement with a reference

  13. Sampling design optimization of a mussel watch-type monitoring program, the French Monitoring Network

    SciTech Connect

    Beliaeff, B.; Claisse, D.; Smith, P.J.

    1995-12-31

    In the French Monitoring Network, trace element and organic concentration in biota has been measured for 15 years on a quarterly basis at over 80 sites scattered along the French coastline. A reduction in the sampling effort may be needed as a result of budget restrictions. A constant budget, however, would allow the advancement of certain research and development projects, such as the feasibility of new chemical analysis. The basic problem confronting the program sampling design optimization is finding optimal numbers of sites in a given non-heterogeneous area and of sampling events within a year at each site. First, they determine a site specific cost function integrating analysis, personnel, and computer costs. Then, within-year and between-site variance components are estimated from the results of a linear model which includes a seasonal component. These two steps provide a cost-precision optimum for each contaminant. An example is given using the data from the 4 sites of the Loire estuary. Over all sites, significant `U`-shaped trends are estimated for Pb, PCBs, {Sigma}DDT and {alpha}-HCH, while PAHs show a significant inverted `U`-shaped curve. For most chemicals the within-year variance appears to be much higher than the between sites variance. This leads to the conclusion that, for this case, reducing the number of sites by two is preferable economically and in terms of monitoring efficiency to reducing the sampling frequency by the same factor. Further implications for the French Monitoring Network are discussed.

  14. Transboundary Air Pollution over the Central Himalayas: Monitoring network and Preliminary Results

    NASA Astrophysics Data System (ADS)

    Zhang, Qianggong; Kang, Shichang

    2016-04-01

    The Himalayas, stretching over 3000 kms along west-east, separates South Asia continent and the Tibetan Plateau with its extreme high altitudes. The South Asia is being increasingly recognized to be among the hotspots of air pollution, posing multi-effects on regional climate and environment. Recent monitoring and projection have indicated an accelerated decrease of glacier and increasing glacier runoff in the Himalayas, and a remarkable phenomenon has been recognized in the Himalayas that long-range transport atmospheric pollutants (e.g., black carbon and dust) deposited on glacier surface can promote glacier melt, and in turns, may liberate historical contaminant legacy in glaciers into downward ecosystems. To understand the air pollution variation and how they can infiltrate the Himalayas and beyond, we started to operate a coordinated atmospheric pollution monitoring network composing 11 sites with 5 in Nepal and 6 in Tibet since April 2013. Atmospheric total suspended particles ( TSP < 100 μm) are collected for 24h at an interval of 3-6 days at all sites. Black carbon, typical persistent organic pollutants (PAHs) and heavy metals (particulate-bounded mercury) are measured to reveal their spatial and temporal distributions. Results revealed a consistent gradient decrease in almost all analyzed parameters along south-north gradient across the Himalayas, with a clear seasonal variation of higher values in pre-monsoon seasons. Analysis of geochemical signatures of carbonaceous aerosols indicated dominant sources from biomass burning and vehicle exhaust. PAHs concentrations and signatures from soils and aerosols indicated that low-ring PAHs can readily transport across the Himalayas. Integrated analysis of satellite images and air mass trajectories suggested that the transboundary air pollution over the Himalayas is episodic and is likely concentrated in pre-monsoon seasons. Our results emphasis the potential transport and impact of air pollution from South Asia

  15. Use of depuration compounds in passive air samplers: results from active sampling-supported field deployment, potential uses, and recommendations.

    PubMed

    Moeckel, Claudia; Harner, Tom; Nizzetto, Luca; Strandberg, Bo; Lindroth, Anders; Jones, Kevin C

    2009-05-01

    Depuration compounds (DCs) are added to passive air samplers (PAS) prior to deployment to account for the wind-dependency of the sampling rate for gas-phase compounds. This correction is particularly useful for providing comparable data for samplers that are deployed in different environments and subject to different meteorological conditions such as wind speeds. Two types of PAS--the polyurethane foam (PUF) disk sampler and semipermeable membrane devices (SPMDs)--were deployed at eight heights on a 100 m tower to test whether the DC approach could yield air concentrations profiles for PCBs and organochlorine pesticides and account for the wind speed gradient with height. Average wind speeds ranged from 0.3 to 4.5 m s(-1) over the 40 day deployment, increasing with height Two low volume active air samples (AAS), one collected at 25 m and one at 73 m over the 40 day deployment showed no significant concentration differences for target compounds. As expected, the target compounds taken up by PAS reflected the wind profile with height This wind-dependency of the PAS was also reflected in the results of the DCs. A correction based on the DC approach successfully accounted for the effect of wind on PAS sampling rates, yielding a profile consistent with the AAS. Interestingly, in terms of absolute air concentrations, there were differences between the AAS and PAS-derived values for some target compounds. These were attributed to different sampling characteristics of the two approaches that may have resulted in slightly different air masses being sampled. Based on the results of this study, guidelines are presented for the use of DCs and for the calibration of PAS using AAS.

  16. Detection of airborne bacteria in a duck production facility with two different personal air sampling devices for an exposure assessment.

    PubMed

    Martin, Elena; Dziurowitz, Nico; Jäckel, Udo; Schäfer, Jenny

    2015-01-01

    Prevalent airborne microorganisms are not well characterized in industrial animal production buildings with respect to their quantity or quality. To investigate the work-related microbial exposure, personal bioaerosol sampling during the whole working day is recommended. Therefore, bioaerosol sampling in a duck hatchery and a duck house with two personal air sampling devices, a filter-based PGP and a NIOSH particle size separator, was performed. Subsequent, quantitative and qualitative analyses were carried out with" culture independent methods. Total cell concentrations (TCC) determined via fluorescence microscopy showed no difference between the two devices. In average, 8 × 10(6) cells/m(3) were determined in the air of the duck hatchery and 5 × 10(7) cells/m(3) in the air of the duck house. A Generated Restriction Fragment Length Polymorphism (RFLP) pattern revealed deviant bacterial compositions comparing samples collected with both devices. Clone library analyses based on 16S rRNA gene sequence analysis from the hatchery's air showed 65% similarity between the two sampling devices. Detailed 16S rRNA gene sequence analyses showed the occurrence of bacterial species like Acinetobacter baumannii, Enterococcus faecalis, Escherichia sp., and Shigella sp.; and a group of Staphylococcus delphini, S. intermedius, and S. pseudintermedius that provided the evidence of potential exposure to risk group 2 bacteria at the hatchery workplace. Size fractionated sampling with the developed by the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) device revealed that pathogenic bacteria would deposit in the inhalable, the thorax, and possibly alveolar dust fraction according to EN481. TCC analysis showed the deposition of bacterial cells in the third stage (< 1μm) at the NIOSH device which implies that bacteria can reach deep into the lungs and contaminate the alveolus after inhalation. Nevertheless, both personal sampling devices

  17. Identification of oxidation products of solanesol produced during air sampling for tobacco smoke by electrospray mass spectrometry and HPLC.

    PubMed

    Tucker, Samuel P; Pretty, Jack R

    2005-10-01

    Solanesol, a 45-carbon, trisesquiterpenoid alcohol found in tobacco leaves and tobacco smoke, has been used as a quantitative marker for tobacco smoke for years. However, solanesol appears to be unreliable as a quantitative marker for tobacco smoke during environmental air sampling because it can be degraded substantially when present as a component of tobacco smoke and by as much as 100% when present as pure solanesol on fortified filters during air sampling. Since there is strong evidence that ozone is the agent responsible for the degradation, solanesol appears to be unreliable as a quantitative marker during indoor air sampling when indoor levels of ozone are greater than about 15 ppb. The degree of loss of pure solanesol is directly proportional to the concentration of ozone and the length of the sampling period and depends on the type of 37 mm membrane filter used for air sampling (PTFE or quartz fiber). While the degree of loss of solanesol is inversely proportional to the relative humidity of the air at a sampling rate of 1.7 L min(-1), the degree of loss is virtually independent of relative humidity at a lower sampling rate; i.e., 0.25 L min(-1). A curve of loss of solanesol on a filter versus concentration of ozone from an ozone generator is virtually identical to a curve segment based on atmospheric ozone under the same conditions of air sampling. Oxidation of solanesol by ozone to approximately 25 to 60% completion produces at least three series of products for a total of at least 26 compounds: (1) isoprenoid acetones, (2)omega-hydroxyisoprenoid acetaldehydes, and (3) isoprenoid oxoaldehydes. All products in each series were tentatively identified as their derivatives with 2-(p-aminophenyl)ethanol (APE) by electrospray mass spectrometry (ES-MS). Ten ozonation products were detected as their 2,4-dinitrophenylhydrazine derivatives by HPLC at 360 nm: 4-oxopentanal and nine isoprenoid acetones (acetone, 6-methyl-5-hepten-2-one, geranylacetone

  18. Journal Article: the National Dioxin Air Monitoring Network (Ndamn): Measurements of CDDs, CDFs and Coplanar PCBs at 15 Rural and 6 National Park Areas of the U.S.: June 1998-December 1999.

    EPA Science Inventory

    The U.S. EPA has established a National Dioxin Air Monitoring Network (NDAMN) to determine the temporal and geographical variability of atmospheric CDDs, CDFs and coplanar PCBs at rural and nonimpacted locations throughout the United States. Currently operating at 32 sampling st...

  19. Evaluation of sampling and analytical methodology for polynuclear aromatic compounds in indoor air. Final report, 1 March-30 September 1985

    SciTech Connect

    Chuang, C.C.; Mack, G.A.; Mondron, P.J.; Petersen, B.A.

    1985-10-01

    The objective of this project was to develop a generic sampling and analytical methodology to characterize the polynuclear aromatic hydrocarbon (PAH) concentrations in air within various microenvironments. The following three studies were performed: evaluation of analytical methods, design of a sampling method, and design of a pilot study. Two analytical methods, high performance liquid chromatography with ultraviolet adsorption and fluorescence detection and gas chromatography/mass spectrometry, were evaluated for the determination of PAHs and their derivatives in air within microenvironments. The results showed that gas chromatography/positive chemical ionization massspectrometry with data acquisition in the selected ion-monitoring mode is the preferred analytical approach. A modified EPA high-volume sampler, consisting of a quartz fiber filter and a polyurethane foam cartridge, is proposed for use in a future experimental study. A literature review was conducted to determine what is known about the contribution of cigarette smoke to the levels of PAHs in air within microenvironments and to evaluate the use of quinoline and isoquinoline as possible marker compounds for the levels of cigarette smoke. A pilot study was designed to assess PAH levels in air found in residences. A study using this design, was conducted in Columbus, Ohio, during the winter of 1983/84. These results can then be applied to a future large-scale study involving the measurement of human exposure to PAH in air.

  20. Social Representations of Hero and Everyday Hero: A Network Study from Representative Samples

    PubMed Central

    Keczer, Zsolt; File, Bálint; Orosz, Gábor; Zimbardo, Philip G.

    2016-01-01

    The psychological investigation of heroism is relatively new. At this stage, inductive methods can shed light on its main aspects. Therefore, we examined the social representations of Hero and Everyday Hero by collecting word associations from two separate representative samples in Hungary. We constructed two networks from these word associations. The results show that the social representation of Hero is more centralized and it cannot be divided into smaller units. The network of Everyday Hero is divided into five units and the significance moves from abstract hero characteristics to concrete social roles and occupations exhibiting pro-social values. We also created networks from the common associations of Hero and Everyday Hero. The structures of these networks show a moderate similarity and the connections are more balanced in case of Everyday Hero. While heroism in general can be the source of inspiration, the promotion of everyday heroism can be more successful in encouraging ordinary people to recognize their own potential for heroic behavior. PMID:27525418

  1. Sampling methods for the quasistationary regime of epidemic processes on regular and complex networks

    NASA Astrophysics Data System (ADS)

    Sander, Renan S.; Costa, Guilherme S.; Ferreira, Silvio C.

    2016-10-01

    A major hurdle in the simulation of the steady state of epidemic processes is that the system will unavoidably visit an absorbing, disease-free state at sufficiently long times due to the finite size of the networks where epidemics evolves. In the present work, we compare different quasistationary (QS) simulation methods where the absorbing states are suitably handled and the thermodynamical limit of the original dynamics can be achieved. We analyze the standard QS (SQS) method, where the sampling is constrained to active configurations, the reflecting boundary condition (RBC), where the dynamics returns to the pre-absorbing configuration, and hub reactivation (HR), where the most connected vertex of the network is reactivated after a visit to an absorbing state. We apply the methods to the contact process (CP) and susceptible-infected-susceptible (SIS) models on regular and scale free networks. The investigated methods yield the same epidemic threshold for both models. For CP, that undergoes a standard collective phase transition, the methods are equivalent. For SIS, whose phase transition is ruled by the hub mutual reactivation, the SQS and HR methods are able to capture localized epidemic phases while RBC is not. We also apply the autocorrelation time as a tool to characterize the phase transition and observe that this analysis provides the same finite-size scaling exponents for the critical relaxation time for the investigated methods. Finally, we verify the equivalence between RBC method and a weak external field for epidemics on networks.

  2. Evaluation of a method to detect Mycobacterium bovis in air samples from infected Eurasian badgers (Meles meles) and their setts.

    PubMed

    Jones, R M; Ashford, R; Cork, J; Palmer, S; Wood, E; Spyvee, P; Parks, S; Bennett, A; Brewer, J; Delahay, R; Chambers, M; Sawyer, J

    2013-05-01

    Environmental air sampling was evaluated as a method to detect the presence of M. bovis in the vicinity of infected badgers and their setts. Airborne particles were collected on gelatine filters using a commercially available air sampling instrument and tested for the presence of M. bovis using bacteriological culture and real-time PCR. The sensitivity of bacteriological culture was broadly similar to that of real-time PCR when testing samples artificially spiked with M. bovis. Sampling was undertaken from directly under the muzzles of badgers which had been experimentally infected with M. bovis (37 samples), within enclosures housing the experimentally infected animals (50 samples), and in the vicinity of setts with resident infected wild badgers (52 samples). The methods employed did not detect M. bovis from either infected badgers or artificial or natural setts known to contain infected animals. However, samples taken at four of the six natural setts were positive for Mycobacterium gordonae.

  3. Spectral pattern recognition of controlled substances in street samples using artificial neural network system

    NASA Astrophysics Data System (ADS)

    Poryvkina, Larisa; Aleksejev, Valeri; Babichenko, Sergey M.; Ivkina, Tatjana

    2011-04-01

    The NarTest fluorescent technique is aimed at the detection of analyte of interest in street samples by recognition of its specific spectral patterns in 3-dimentional Spectral Fluorescent Signatures (SFS) measured with NTX2000 analyzer without chromatographic or other separation of controlled substances from a mixture with cutting agents. The illicit drugs have their own characteristic SFS features which can be used for detection and identification of narcotics, however typical street sample consists of a mixture with cutting agents: adulterants and diluents. Many of them interfere the spectral shape of SFS. The expert system based on Artificial Neural Networks (ANNs) has been developed and applied for such pattern recognition in SFS of street samples of illicit drugs.

  4. Scheduling whole-air samples above the Trade Wind Inversion from SUAS using real-time sensors

    NASA Astrophysics Data System (ADS)

    Freer, J. E.; Greatwood, C.; Thomas, R.; Richardson, T.; Brownlow, R.; Lowry, D.; MacKenzie, A. R.; Nisbet, E. G.

    2015-12-01

    Small Unmanned Air Systems (SUAS) are increasingly being used in science applications for a range of applications. Here we explore their use to schedule the sampling of air masses up to 2.5km above ground using computer controlled bespoked Octocopter platforms. Whole-air sampling is targeted above, within and below the Trade Wind Inversion (TWI). On-board sensors profiled the TWI characteristics in real time on ascent and, hence, guided the altitudes at which samples were taken on descent. The science driver for this research is investigation of the Southern Methane Anomaly and, more broadly, the hemispheric-scale transport of long-lived atmospheric tracers in the remote troposphere. Here we focus on the practical application of SUAS for this purpose. Highlighting the need for mission planning, computer control, onboard sensors and logistics in deploying such technologies for out of line-of-sight applications. We show how such a platform can be deployed successfully, resulting in some 60 sampling flights within a 10 day period. Challenges remain regarding the deployment of such platforms routinely and cost-effectively, particularly regarding training and support. We present some initial results from the methane sampling and its implication for exploring and understanding the Southern Methane Anomaly.

  5. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT - BAGHOUSE FILTRATION PRODUCTS - AIR PURATOR CORPORATION HUYGLAS 1405M FILTER SAMPLE

    EPA Science Inventory

    Baghouse filtration products (BFPs) were evaluated by the Air Pollution Control Technology (APCT) pilot of the Environmental Technology Verification (ETV) Program. The performance factor verified was the mean outlet particle concentration for the filter fabric as a function of th...

  6. Comparison of precipitation chemistry measurements obtained by the Canadian Air and Precipitation Monitoring Network and National Atmospheric Deposition Program for the period 1995-2004

    USGS Publications Warehouse

    Wetherbee, Gregory A.; Shaw, Michael J.; Latysh, Natalie E.; Lehmann, Christopher M.B.; Rothert, Jane E.

    2010-01-01

    Precipitation chemistry and depth measurements obtained by the Canadian Air and Precipitation Monitoring Network (CAPMoN) and the US National Atmospheric Deposition Program/National Trends Network (NADP/NTN) were compared for the 10-year period 1995–2004. Colocated sets of CAPMoN and NADP instrumentation, consisting of precipitation collectors and rain gages, were operated simultaneously per standard protocols for each network at Sutton, Ontario and Frelighsburg, Ontario, Canada and at State College, PA, USA. CAPMoN samples were collected daily, and NADP samples were collected weekly, and samples were analyzed exclusively by each network’s laboratory for pH, H + , Ca2+  , Mg2+  , Na + , K + , NH+4 , Cl − , NO−3 , and SO2−4 . Weekly and annual precipitation-weighted mean concentrations for each network were compared. This study is a follow-up to an earlier internetwork comparison for the period 1986–1993, published by Alain Sirois, Robert Vet, and Dennis Lamb in 2000. Median weekly internetwork differences for 1995–2004 data were the same to slightly lower than for data for the previous study period (1986–1993) for all analytes except NO−3 , SO2−4 , and sample depth. A 1994 NADP sampling protocol change and a 1998 change in the types of filters used to process NADP samples reversed the previously identified negative bias in NADP data for hydrogen-ion and sodium concentrations. Statistically significant biases (α = 0.10) for sodium and hydrogen-ion concentrations observed in the 1986–1993 data were not significant for 1995–2004. Weekly CAPMoN measurements generally are higher than weekly NADP measurements due to differences in sample filtration and field instrumentation, not sample evaporation, contamination, or analytical laboratory differences.

  7. Exposure assessment of monoterpenes and styrene: a comparison of air sampling and biomonitoring

    PubMed Central

    Liljelind, I; Rappaport, S; Eriksson, K; Andersson, J; Bergdahl, I; Sunesson, A; Jarvholm, B

    2003-01-01

    Background: Within- and between-worker variance components have seldom been reported for both environmental and biological data collected from the same persons. Aims: To estimate these variance components and their ratio for air contaminants and urinary metabolites in two different work environments and to predict the attenuation of exposure-response relationships based on these measures. Methods: Parallel measurements of air and urine were performed among workers exposed to monoterpenes in sawmills (urinary metabolite: verbenol) and styrene in reinforced plastics factories (urinary metabolite: mandelic acid). Results: Among the sawmill workers, variance components of the air and urinary verbenol results were similar; for the reinforced plastics workers the estimated between-worker variance component was greater for styrene in air than mandelic acid in urine. This suggests that attenuation bias would be about equal if air or biological monitoring were employed for monoterpene exposures, but would be greater if urinary mandelic acid were used instead of airborne styrene in an investigation of styrene exposure. Conclusions: Personal air samplers provide data with similar or superior quality to urinary metabolites as measures of exposure to these monoterpenes in sawmills and styrene in reinforced plastics factories. PMID:12883022

  8. Mutual Information in the Air Quality Monitoring Network of Bogota - Colombia

    NASA Astrophysics Data System (ADS)

    Guerrero, O. J.; Jimenez-Pizarro, R.

    2012-12-01

    Large urban areas in the developing world are characterized by high population density and a great variety of activities responsible for emission of trace gases and particulate matter to the atmosphere. In general, these pollutants are unevenly distributed over cities according to the location of sources, meteorological variability and geographical features. Urban air quality monitoring networks are primarily designed to protect public health. The meteorological and air quality information gathered by monitoring networks can also be used to understand pollutant sources, sinks, and dispersion processes and to assess the spatial coverage of the network itself. Several statistical and numerical simulation methods allow for the identification of the domain that influences observations at each of the stations, i.e, the zone and respective population truly covered by the measurements. We focused on Bogota, Colombia, a dense city of approximately 9.6 million inhabitants in its metropolitan area. We analyzed the measurements obtained by the Bogotá Air Quality Monitoring Network (RMCAB) between the years 1997 and 2010 for TSP, PM10, CO, NOx and O3. RMCAB is composed of 16 stations, 13 of which are fixed and measure both atmospheric pollutants and meteorological variables. The method applied consisted of a statistical approach based on the mutual information that each station shares with its complement, i.e. the set formed by the other stations of the network. In order to improve our understanding and interpretation of the results, virtual data created for selected receptors along a simple modeled Gaussian plume spreading throughout Bogotá was analyzed. In this Gaussian model, we accounted for the prevailing weather conditions of this city and for different emission features under which the pollutants are emitted. The spatial location of the monitoring stations and emission sources, and the quality of the measurements are relevant factors when assessing the mutual

  9. Using maximum entropy modeling for optimal selection of sampling sites for monitoring networks

    USGS Publications Warehouse

    Stohlgren, Thomas J.; Kumar, Sunil; Barnett, David T.; Evangelista, Paul H.

    2011-01-01

    Environmental monitoring programs must efficiently describe state shifts. We propose using maximum entropy modeling to select dissimilar sampling sites to capture environmental variability at low cost, and demonstrate a specific application: sample site selection for the Central Plains domain (453,490 km2) of the National Ecological Observatory Network (NEON). We relied on four environmental factors: mean annual temperature and precipitation, elevation, and vegetation type. A “sample site” was defined as a 20 km × 20 km area (equal to NEON’s airborne observation platform [AOP] footprint), within which each 1 km2 cell was evaluated for each environmental factor. After each model run, the most environmentally dissimilar site was selected from all potential sample sites. The iterative selection of eight sites captured approximately 80% of the environmental envelope of the domain, an improvement over stratified random sampling and simple random designs for sample site selection. This approach can be widely used for cost-efficient selection of survey and monitoring sites.

  10. Perfluoroalkyl acids and their precursors in indoor air sampled in children's bedrooms.

    PubMed

    Winkens, Kerstin; Koponen, Jani; Schuster, Jasmin; Shoeib, Mahiba; Vestergren, Robin; Berger, Urs; Karvonen, Anne M; Pekkanen, Juha; Kiviranta, Hannu; Cousins, Ian T

    2017-03-01

    The contamination levels and patterns of perfluoroalkyl acids (PFAAs) and their precursors in indoor air of children's bedrooms in Finland, Northern Europe, were investigated. Our study is among the most comprehensive indoor air monitoring studies (n = 57) and to our knowledge the first one to analyse air in children's bedrooms for PFASs (17 PFAAs and 9 precursors, including two acrylates, 6:2 FTAC and 6:2 FTMAC). The most frequently detected compound was 8:2 fluorotelomer alcohol (8:2 FTOH) with the highest median concentration (3570 pg/m(3)). FTOH concentrations were generally similar to previous studies, indicating that in 2014/2015 the impact of the industrial transition had been minor on FTOH levels in indoor air. However, in contrast to earlier studies (with one exception), median concentrations of 6:2 FTOH were higher than 10:2 FTOH. The C8 PFAAs are still the most abundant acids, even though they have now been phased out by major manufacturers. The mean concentrations of FOSE/As, especially MeFOSE (89.9 pg/m(3)), were at least an order of magnitude lower compared to previous studies. Collectively the comparison of FTOHs, PFAAs and FOSE/FOSAs with previous studies indicates that indoor air levels of PFASs display a time lag to changes in production of several years. This is the first indoor air study investigating 6:2 FTMAC, which was frequently detected (58%) and displayed some of the highest maximum concentrations (13 000 pg/m(3)). There were several statistically significant correlations between particular house and room characteristics and PFAS concentrations, most interestingly higher EtFOSE air concentrations in rooms with plastic floors compared to wood or laminate.

  11. Preliminary results of investigations into the use of artificial neural networks for discriminating gas chromatograph mass spectra of remote samples

    NASA Technical Reports Server (NTRS)

    Geller, Harold A.; Norris, Eugene; Warnock, Archibald, III

    1991-01-01

    Neural networks trained using mass spectra data from the National Institute of Standards and Technology (NIST) are studied. The investigations also included sample data from the gas chromatograph mass spectrometer (GCMS) instrument aboard the Viking Lander, obtained from the National Space Science Data Center. The work performed to data and the preliminary results from the training and testing of neural networks are described. These preliminary results are presented for the purpose of determining the viability of applying artificial neural networks in discriminating mass spectra samples from remote instrumentation such as the Mars Rover Sample Return Mission and the Cassini Probe.

  12. Intraregional links between the trends in air pollutants observed at the EANET network sites for 2000-2014

    NASA Astrophysics Data System (ADS)

    Gromov, Sergey A.; Trifonova-Yakovleva, Alisa; Gromov, Sergey S.

    2016-04-01

    Recent changes in economic development tendencies and environmental protection policies in the East Asian countries raise hopes for improvement of regional air quality in this vast region populated by more than 3 billion people. To recognize anticipated changes in atmospheric pollutants levels, deposition rates and impact on the environment, the Acid Deposition Monitoring Network in East Asia (EANET, http://www.eanet.asia/) is regularly operating region-wide since 2000 in 13 countries. The network provides continuous monitoring data on the air quality and precipitation (including gas-phase and particulate chemistry) at 55 monitoring sites, including 20 remote and 14 rural sites. Observation of soil and inland water environments are performed at more than 30 monitoring sites [1]. In this study we focus on 1) the data quality assessment and preparation and 2) analysis of temporal trends of compositions observed at selected 26 non-urban EANET stations. Speciation includes gas-phase (SO2, HNO3, HCl, NH3) and particulate matter (SO42-, NO3-, Cl-, NH4+, Na+, K+, Mg2+, Ca2+) abundances analysed in samples collected using filterpack technique with sampling duration/frequency of one-two weeks. Data quality assessment (distribution test and manual inspection) allowed us to remove/repair random and operator errors. Wrong sample timing was found for 0.37% (severe) and 34% (mild inconsistency) of the total of 7630 samples regarded. Erroneous data flagging (e.g. missing or below the detection limit) was repaired for 9.3%, respectively. Some 1.8% of severely affected data were corrected (where possible) or removed. Thus refined 15-year dataset is made available for the scientific community. For convenience, we also provide data in netCDF format (per station or in an assembly). Based on this refined dataset, we performed trend analysis using several statistical approaches including quantile regression which provides robust results against outliers and better understanding of trend

  13. The lung cancer breath signature: a comparative analysis of exhaled breath and air sampled from inside the lungs

    PubMed Central

    Capuano, Rosamaria; Santonico, Marco; Pennazza, Giorgio; Ghezzi, Silvia; Martinelli, Eugenio; Roscioni, Claudio; Lucantoni, Gabriele; Galluccio, Giovanni; Paolesse, Roberto; Di Natale, Corrado; D’Amico, Arnaldo

    2015-01-01

    Results collected in more than 20 years of studies suggest a relationship between the volatile organic compounds exhaled in breath and lung cancer. However, the origin of these compounds is still not completely elucidated. In spite of the simplistic vision that cancerous tissues in lungs directly emit the volatile metabolites into the airways, some papers point out that metabolites are collected by the blood and then exchanged at the air-blood interface in the lung. To shed light on this subject we performed an experiment collecting both the breath and the air inside both the lungs with a modified bronchoscopic probe. The samples were measured with a gas chromatography-mass spectrometer (GC-MS) and an electronic nose. We found that the diagnostic capability of the electronic nose does not depend on the presence of cancer in the sampled lung, reaching in both cases an above 90% correct classification rate between cancer and non-cancer samples. On the other hand, multivariate analysis of GC-MS achieved a correct classification rate between the two lungs of only 76%. GC-MS analysis of breath and air sampled from the lungs demonstrates a substantial preservation of the VOCs pattern from inside the lung to the exhaled breath. PMID:26559776

  14. Thermal desorption-gas chromatography-mass spectrometry method to determine phthalate and organophosphate esters from air samples.

    PubMed

    Aragón, M; Borrull, F; Marcé, R M

    2013-08-16

    A method based on thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed to determine four organophosphate esters, seven phthalate esters, and bis(2-ethylhexyl) adipate in the gas phase from harbour and urban air samples. The method involves the sampling of 1.5L of air in a Tenax TA sorbent tube followed by thermal desorption (using a Tenax TA cryogenic trap) coupled to gas chromatography-mass spectrometry. The repeatability of the method expressed as %RSD (n=3) is less than 15% and the MQLs are between 0.007μgm(-3) (DMP, TBP, BBP, TPP and DnOP) and 6.7μgm(-3) (DEHP). The method was successfully applied in two areas (urban and harbour) testing two and three points in each one, respectively. Some of these compounds were found in both urban and harbour samples. Di-(2-ethylhexyl)phthalate was the most abundant compound found in both areas at concentration levels between 6.7μgm(-3) and 136.4μgm(-3). This study demonstrates that thermal desorption is an efficient method for the determination of these semi-volatile compounds in the gas phase fraction of air samples.

  15. Evaluation of mixing downstream of tees in duct systems with respect to single point representative air sampling.

    PubMed

    Kim, Taehong; O'Neal, Dennis L; Ortiz, Carlos

    2006-09-01

    Air duct systems in nuclear facilities must be monitored with continuous sampling in case of an accidental release of airborne radionuclides. The purpose of this work is to identify the air sampling locations where the velocity and contaminant concentrations fall below the 20% coefficient of variation required by the American National Standards Institute/Health Physics Society N13.1-1999. Experiments of velocity and tracer gas concentration were conducted on a generic "T" mixing system which included combinations of three sub ducts, one main duct, and air velocities from 0.5 to 2 m s (100 to 400 fpm). The experimental results suggest that turbulent mixing provides the accepted velocity coefficients of variation after 6 hydraulic diameters downstream of the T-junction. About 95% of the cases achieved coefficients of variation below 10% by 6 hydraulic diameters. However, above a velocity ratio (velocity in the sub duct/velocity in the main duct) of 2, velocity profiles were uniform in a shorter distance downstream of the T-junction as the velocity ratio went up. For the tracer gas concentration, the distance needed for the coefficients of variation to drop 20% decreased with increasing velocity ratio due to the sub duct airflow momentum. The results may apply to other duct systems with similar geometries and, ultimately, be a basis for selecting a proper sampling location under the requirements of single point representative sampling.

  16. The lung cancer breath signature: a comparative analysis of exhaled breath and air sampled from inside the lungs.

    PubMed

    Capuano, Rosamaria; Santonico, Marco; Pennazza, Giorgio; Ghezzi, Silvia; Martinelli, Eugenio; Roscioni, Claudio; Lucantoni, Gabriele; Galluccio, Giovanni; Paolesse, Roberto; Di Natale, Corrado; D'Amico, Arnaldo

    2015-11-12

    Results collected in more than 20 years of studies suggest a relationship between the volatile organic compounds exhaled in breath and lung cancer. However, the origin of these compounds is still not completely elucidated. In spite of the simplistic vision that cancerous tissues in lungs directly emit the volatile metabolites into the airways, some papers point out that metabolites are collected by the blood and then exchanged at the air-blood interface in the lung. To shed light on this subject we performed an experiment collecting both the breath and the air inside both the lungs with a modified bronchoscopic probe. The samples were measured with a gas chromatography-mass spectrometer (GC-MS) and an electronic nose. We found that the diagnostic capability of the electronic nose does not depend on the presence of cancer in the sampled lung, reaching in both cases an above 90% correct classification rate between cancer and non-cancer samples. On the other hand, multivariate analysis of GC-MS achieved a correct classification rate between the two lungs of only 76%. GC-MS analysis of breath and air sampled from the lungs demonstrates a substantial preservation of the VOCs pattern from inside the lung to the exhaled breath.

  17. The lung cancer breath signature: a comparative analysis of exhaled breath and air sampled from inside the lungs

    NASA Astrophysics Data System (ADS)

    Capuano, Rosamaria; Santonico, Marco; Pennazza, Giorgio; Ghezzi, Silvia; Martinelli, Eugenio; Roscioni, Claudio; Lucantoni, Gabriele; Galluccio, Giovanni; Paolesse, Roberto; di Natale, Corrado; D'Amico, Arnaldo

    2015-11-01

    Results collected in more than 20 years of studies suggest a relationship between the volatile organic compounds exhaled in breath and lung cancer. However, the origin of these compounds is still not completely elucidated. In spite of the simplistic vision that cancerous tissues in lungs directly emit the volatile metabolites into the airways, some papers point out that metabolites are collected by the blood and then exchanged at the air-blood interface in the lung. To shed light on this subject we performed an experiment collecting both the breath and the air inside both the lungs with a modified bronchoscopic probe. The samples were measured with a gas chromatography-mass spectrometer (GC-MS) and an electronic nose. We found that the diagnostic capability of the electronic nose does not depend on the presence of cancer in the sampled lung, reaching in both cases an above 90% correct classification rate between cancer and non-cancer samples. On the other hand, multivariate analysis of GC-MS achieved a correct classification rate between the two lungs of only 76%. GC-MS analysis of breath and air sampled from the lungs demonstrates a substantial preservation of the VOCs pattern from inside the lung to the exhaled breath.

  18. Fault Isolation Filter for Networked Control System with Event-Triggered Sampling Scheme

    PubMed Central

    Li, Shanbin; Sauter, Dominique; Xu, Bugong

    2011-01-01

    In this paper, the sensor data is transmitted only when the absolute value of difference between the current sensor value and the previously transmitted one is greater than the given threshold value. Based on this send-on-delta scheme which is one of the event-triggered sampling strategies, a modified fault isolation filter for a discrete-time networked control system with multiple faults is then implemented by a particular form of the Kalman filter. The proposed fault isolation filter improves the resource utilization with graceful fault estimation performance degradation. An illustrative example is given to show the efficiency of the proposed method. PMID:22346590

  19. Fault isolation filter for networked control system with event-triggered sampling scheme.

    PubMed

    Li, Shanbin; Sauter, Dominique; Xu, Bugong

    2011-01-01

    In this paper, the sensor data is transmitted only when the absolute value of difference between the current sensor value and the previously transmitted one is greater than the given threshold value. Based on this send-on-delta scheme which is one of the event-triggered sampling strategies, a modified fault isolation filter for a discrete-time networked control system with multiple faults is then implemented by a particular form of the Kalman filter. The proposed fault isolation filter improves the resource utilization with graceful fault estimation performance degradation. An illustrative example is given to show the efficiency of the proposed method.

  20. Analyzing the evolutionary mechanisms of the Air Transportation System-of-Systems using network theory and machine learning algorithms

    NASA Astrophysics Data System (ADS)

    Kotegawa, Tatsuya

    Complexity in the Air Transportation System (ATS) arises from the intermingling of many independent physical resources, operational paradigms, and stakeholder interests, as well as the dynamic variation of these interactions over time. Currently, trade-offs and cost benefit analyses of new ATS concepts are carried out on system-wide evaluation simulations driven by air traffic forecasts that assume fixed airline routes. However, this does not well reflect reality as airlines regularly add and remove routes. A airline service route network evolution model that projects route addition and removal was created and combined with state-of-the-art air traffic forecast methods to better reflect the dynamic properties of the ATS in system-wide simulations. Guided by a system-of-systems framework, network theory metrics and machine learning algorithms were applied to develop the route network evolution models based on patterns extracted from historical data. Constructing the route addition section of the model posed the greatest challenge due to the large pool of new link candidates compared to the actual number of routes historically added to the network. Of the models explored, algorithms based on logistic regression, random forests, and support vector machines showed best route addition and removal forecast accuracies at approximately 20% and 40%, respectively, when validated with historical data. The combination of network evolution models and a system-wide evaluation tool quantified the impact of airline route network evolution on air traffic delay. The expected delay minutes when considering network evolution increased approximately 5% for a forecasted schedule on 3/19/2020. Performance trade-off studies between several airline route network topologies from the perspectives of passenger travel efficiency, fuel burn, and robustness were also conducted to provide bounds that could serve as targets for ATS transformation efforts. The series of analysis revealed that high

  1. Investigation on per- and polyfluorinated compounds in paired samples of house dust and indoor air from Norwegian homes.

    PubMed

    Haug, Line S; Huber, Sandra; Schlabach, Martin; Becher, Georg; Thomsen, Cathrine

    2011-10-01

    Per- and polyfluorinated compounds (PFCs) have been found to be ubiquitously distributed in human populations, however the sources of human exposure are not fully characterized. A wide range of PFCs were determined in paired samples of indoor air and dust from 41 Norwegian households. Up to 18 ionic and 9 neutral PFCs were detected. The concentrations found are comparable to or lower than what has previously been reported in North America, Europe, and Asia. The highest median concentrations in dust were observed for perfluorohexanoic acid (28 ng/g), perfluorononanoic acid (23 ng/g), perfluorododecanoic acid (19 ng/g), and perfluorooctanoic acid (18 ng/g). However, perfluoroalkyl sulfonic acids (PFSAs) were also frequently detected. Fluortelomer alcohols were the most prominent compounds found in indoor air, with median concentrations for 8:2 fluortelomer alcohol, 10:2 fluortelomer alcohol, and 6:2 fluortelomer alcohol of 5173, 2822, and 933 pg/m(3) air, respectively. All perfluoroalkyl sulfonamides and sulfonamidoethanols (FOSA/FOSEs) were detected in more than 40% of the air samples. For the first time, significant positive correlations (p < 0.05) between PFSAs in house dust and FOSA/FOSEs in the indoor air have been shown, supporting the hypothesis that FOSA/FOSEs may be transformed to PFSAs. Further, we found the age of the residence to be a predictor of PFC concentrations in both indoor air and house dust. These results are important for estimating the exposure to PFCs from the indoor environment and for characterization of exposure pathways.

  2. Porosity, permeability and 3D fracture network characterisation of dolomite reservoir rock samples.

    PubMed

    Voorn, Maarten; Exner, Ulrike; Barnhoorn, Auke; Baud, Patrick; Reuschlé, Thierry

    2015-03-01

    With fractured rocks making up an important part of hydrocarbon reservoirs worldwide, detailed analysis of fractures and fracture networks is essential. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) however suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this paper, we therefore explore the use of an additional method - non-destructive 3D X-ray micro-Computed Tomography (μCT) - to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. We process the 3D μCT data in this study by a Hessian-based fracture filtering routine and can successfully extract porosity, fracture aperture, fracture density and fracture orientations - in bulk as well as locally. Additionally, thin sections made from selected plug samples provide 2D information with a much higher detail than the μCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) towards more realistic reservoir conditions. This study shows that 3D μCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that although there are limitations, several important parameters can be extracted. μCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these and

  3. Porosity, permeability and 3D fracture network characterisation of dolomite reservoir rock samples

    PubMed Central

    Voorn, Maarten; Exner, Ulrike; Barnhoorn, Auke; Baud, Patrick; Reuschlé, Thierry

    2015-01-01

    With fractured rocks making up an important part of hydrocarbon reservoirs worldwide, detailed analysis of fractures and fracture networks is essential. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) however suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this paper, we therefore explore the use of an additional method – non-destructive 3D X-ray micro-Computed Tomography (μCT) – to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. We process the 3D μCT data in this study by a Hessian-based fracture filtering routine and can successfully extract porosity, fracture aperture, fracture density and fracture orientations – in bulk as well as locally. Additionally, thin sections made from selected plug samples provide 2D information with a much higher detail than the μCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) towards more realistic reservoir conditions. This study shows that 3D μCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that although there are limitations, several important parameters can be extracted. μCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these

  4. Direct Trace Element Analysis of Liquid Blood Samples by In-Air Ion Beam Analytical Techniques (PIXE-PIGE).

    PubMed

    Huszank, Robert; Csedreki, László; Török, Zsófia

    2017-02-07

    There are various liquid materials whose elemental composition is of interest in various fields of science and technology. In many cases, sample preparation or the extraction can be complicated, or it would destroy the original environment before the analysis (for example, in the case of biological samples). However, multielement direct analysis of liquid samples can be realized by an external PIXE-PIGE measurement system. Particle-induced X-ray and gamma-ray emission spectroscopy (PIXE, PIGE) techniques were applied in external (in-air) microbeam configuration for the trace and main element determination of liquid samples. The direct analysis of standard solutions of several metal salts and human blood samples (whole blood, blood serum, blood plasma, and formed elements) was realized. From the blood samples, Na, P, S, Cl, K, Ca, Fe, Cu, Zn, and Br elemental concentrations were determined. The focused and scanned ion beam creates an opportunity to analyze very small volume samples (∼10 μL). As the sample matrix consists of light elements, the analysis is possible at ppm level. Using this external beam setup, it was found that it is possible to determine elemental composition of small-volume liquid samples routinely, while the liquid samples do not require any preparation processes, and thus, they can be analyzed directly. In the case of lower concentrations, the method is also suitable for the analysis (down to even ∼1 ppm level) but with less accuracy and longer measurement times.

  5. Robust reliable control design for networked control system with sampling communication

    NASA Astrophysics Data System (ADS)

    Sakthivel, R.; Santra, Srimanta; Mathiyalagan, K.; Su, Hongye

    2015-12-01

    In this article, the problem of robust exponential stability and reliable stabilisation for a class of continuous-time networked control systems (NCSs) with a sample-data controller and unknown time-varying sampling rate is considered. The analysis is based on average dwell-time, Lyapunov-Krasovskii functional and linear matrix inequality (LMI) technique. The delay-dependent criteria are developed for ensuring the robust exponential stability of the considered NCSs. The obtained conditions are formulated in terms of LMIs that can easily be solved by using standard software packages. Furthermore, the result is extended to study the robust stabilisation for NCS with parameter uncertainties. A state feedback controller is constructed in terms of the solution to a set of LMIs, which guarantee the robust exponential stabilisation of NCS and the controller. Finally, numerical examples are presented to illustrate the effectiveness of the obtained results.

  6. Combining Efficient Conformational Sampling with a Deformable Elastic Network Model Facilitates Structure Refinement at Low Resolution

    PubMed Central

    Schröder, Gunnar F.; Brunger, Axel T.; Levitt, Michael

    2008-01-01

    Summary Structural studies of large proteins and protein assemblies are a difficult and pressing challenge in molecular biology. Experiments often yield only low-resolution or sparse data which are not sufficient to fully determine atomistic structures. We have developed a general geometry-based algorithm that efficiently samples conformational space under constraints imposed by low-resolution density maps obtained from electron microscopy or X-ray crystallography experiments. A deformable elastic network (DEN) is used to restrain the sampling to prior knowledge of an approximate structure. The DEN restraints dramatically reduce over-fitting, especially at low resolution. Cross-validation is used to optimally weight the structural information and experimental data. Our algorithm is robust even for noise-added density maps and has a large radius of convergence for our test case. The DEN restraints can also be used to enhance reciprocal space simulated annealing refinement. PMID:18073112

  7. Hydrogen isotopes from source water to leaf lipid in a continental-scale sample network

    NASA Astrophysics Data System (ADS)

    Nelson, Daniel; Kahmen, Ansgar

    2015-04-01

    Sedimentary plant waxes are useful paleoclimate proxies because they are preserved in depositional settings on geologic timescales and the isotopic composition of the hydrogen in these molecules reflects that of the source water available during biosynthesis. This application is based largely on empirical calibrations that have demonstrated continental-scale correlations between source water and lipid hydrogen isotope values. However, the importance of variable net isotopic fractionation between source water and lipid for different species and environmental conditions is increasingly recognized. Isotopic enrichment of leaf water during transpiration is key among these secondary factors, and is itself sensitive to changes in hydroclimate. Leaf water enrichment also occurs prior to photosynthetic water uptake, and is therefore independent from cellular-level biomarker synthesis. Mechanistic models can predict the mean leaf water hydrogen isotope composition from readily available meteorological variables. This permits global-scale isoscape maps of leaf water isotopic composition and enrichment above source water to be generated, but these models have not been widely validated at continental spatial scales. We have established a network of twenty-one sites across Europe where we are sampling for leaf-, xylem-, and soil-water isotopes (H and O) at approximately 5-week intervals over the summer growing season. We augment the sample set with weekly to monthly precipitation samples and early- and late-season plant wax lipid samples. Collaborators at each site are conducting the sampling, and most sites are members of the FLUXNET tower network that also record high-resolution meteorological data. We present information on the implementation of the network and preliminary results from the 2014 summer season. The complete dataset will be used to track the evolution of water isotopes from source to leaf water and from leaf water to lipid hydrogen across diverse environments

  8. The use of electrochemical sensors for monitoring urban air quality in low-cost, high-density networks

    NASA Astrophysics Data System (ADS)

    Mead, M. I.; Popoola, O. A. M.; Stewart, G. B.; Landshoff, P.; Calleja, M.; Hayes, M.; Baldovi, J. J.; McLeod, M. W.; Hodgson, T. F.; Dicks, J.; Lewis, A.; Cohen, J.; Baron, R.; Saffell, J. R.; Jones, R. L.

    2013-05-01

    Measurements at appropriate spatial and temporal scales are essential for understanding and monitoring spatially heterogeneous environments with complex and highly variable emission sources, such as in urban areas. However, the costs and complexity of conventional air quality measurement methods means that measurement networks are generally extremely sparse. In this paper we show that miniature, low-cost electrochemical gas sensors, traditionally used for sensing at parts-per-million (ppm) mixing ratios can, when suitably configured and operated, be used for parts-per-billion (ppb) level studies for gases re