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Sample records for air mass trajectory

  1. Spatial variability of hailfalls in France: an analysis of air mass retro-trajectories

    NASA Astrophysics Data System (ADS)

    Hermida, Lucía; Merino, Andrés; Sánchez, José Luis; Berthet, Claude; Dessens, Jean; López, Laura; Fernández-González, Sergio; Gascón, Estíbaliz; García-Ortega, Eduardo

    2014-05-01

    Hail is the main meteorological risk in south-west France, with the strongest hailfalls being concentrated in just a few days. Specifically, this phenomenon occurs most often and with the greatest severity in the Midi-Pyrénées area. Previous studies have revealed the high spatial variability of hailfall in this part of France, even leading to different characteristics being recorded on hailpads that were relatively close together. For this reason, an analysis of the air mass trajectories was carried out at ground level and at altitude, which subsequently led to the formation of the hail recorded by these hailpads. It is already known that in the study zone, the trajectories of the storms usually stretch for long distances and are oriented towards the east, leading to hailstones with diameters in excess of 3 cm, and without any change in direction above 3 km. We analysed different days with hail precipitation where there was at least one stone with a diameter of 3 cm or larger. Using the simulations from these days, an analysis of the backward trajectories of the air masses was carried out. We used the HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) to determine the origin of the air masses, and tracked them toward each of the hailpads that were hit during the day studied. The height of the final points was the height of the impacted hailpads. Similarly, the backward trajectories for different heights were also established. Finally, the results show how storms that affect neighbouring hailpads come from very different air masses; and provide a deeper understanding of the high variability that affects the characteristics of hailfalls. Acknowledgements The authors would like to thank the Regional Government of Castile-León for its financial support through the project LE220A11-2. This study was supported by the following grants: GRANIMETRO (CGL2010-15930); MICROMETEO (IPT-310000-2010-22).

  2. Stable isotope composition of waters in the Great Basin, United States 1. Air-mass trajectories

    USGS Publications Warehouse

    Friedman, I.; Harris, J.M.; Smith, G.I.; Johnson, C.A.

    2002-01-01

    Isentropic trajectories, calculated using the NOAA/Climate Monitoring and Diagnostics Laboratory's isentropic transport model, were used to determine air-parcel origins and the influence of air mass trajectories on the isotopic composition of precipitation events that occurred between October 1991 and September 1993 at Cedar City, Utah, and Winnemucca, Nevada. Examination of trajectories that trace the position of air parcels backward in time for 10 days indicated five distinct regions of water vapor origin: (1) Gulf of Alaska and North Pacific, (2) central Pacific, (3) tropical Pacific, (4) Gulf of Mexico, and (5) continental land mass. Deuterium (??D) and oxygen-18 (??18O) analyses were made of precipitation representing 99% of all Cedar City events. Similar analyses were made on precipitation representing 66% of the precipitation falling at Winnemucca during the same period. The average isotopic composition of precipitation derived from each water vapor source was determined. More than half of the precipitation that fell at both sites during the study period originated in the tropical Pacific and traveled northeast to the Great Basin; only a small proportion traversed the Sierra Nevada. The isotopic composition of precipitation is determined by air-mass origin and its track to the collection station, mechanism of droplet formation, reequilibration within clouds, and evaporation during its passage from cloud to ground. The Rayleigh distillation model can explain the changes in isotopic composition of precipitation as an air mass is cooled pseudo-adiabatically during uplift. However, the complicated processes that take place in the rapidly convecting environment of cumulonimbus and other clouds that are common in the Great Basin, especially in summer, require modification of this model because raindrops that form in the lower portion of those clouds undergo isotopic change as they are elevated to upper levels of the clouds from where they eventually drop to the

  3. Impact of maritime air mass trajectories on the Western European coast urban aerosol.

    PubMed

    Almeida, S M; Silva, A I; Freitas, M C; Dzung, H M; Caseiro, A; Pio, C A

    2013-01-01

    Lisbon is the largest urban area in the Western European coast. Due to this geographical position the Atlantic Ocean serves as an important source of particles and plays an important role in many atmospheric processes. The main objectives of this study were to (1) perform a chemical characterization of particulate matter (PM2.5) sampled in Lisbon, (2) identify the main sources of particles, (3) determine PM contribution to this urban area, and (4) assess the impact of maritime air mass trajectories on concentration and composition of respirable PM sampled in Lisbon. During 2007, PM2.5 was collected on a daily basis in the center of Lisbon with a Partisol sampler. The exposed Teflon filters were measured by gravimetry and cut into two parts: one for analysis by instrumental neutron activation analysis (INAA) and the other by ion chromatography (IC). Principal component analysis (PCA) and multilinear regression analysis (MLRA) were used to identify possible sources of PM2.5 and determine mass contribution. Five main groups of sources were identified: secondary aerosols, traffic, calcium, soil, and sea. Four-day backtracking trajectories ending in Lisbon at the starting sampling time were calculated using the HYSPLIT model. Results showed that maritime transport scenarios were frequent. These episodes were characterized by a significant decrease of anthropogenic aerosol concentrations and exerted a significant role on air quality in this urban area.

  4. Identification of aerosol types over an urban site based on air-mass trajectory classification

    NASA Astrophysics Data System (ADS)

    Pawar, G. V.; Devara, P. C. S.; Aher, G. R.

    2015-10-01

    Columnar aerosol properties retrieved from MICROTOPS II Sun Photometer measurements during 2010-2013 over Pune (18°32‧N; 73°49‧E, 559 m amsl), a tropical urban station in India, are analyzed to identify aerosol types in the atmospheric column. Identification/classification is carried out on the basis of dominant airflow patterns, and the method of discrimination of aerosol types on the basis of relation between aerosol optical depth (AOD500 nm) and Ångström exponent (AE, α). Five potential advection pathways viz., NW/N, SW/S, N, SE/E and L have been identified over the observing site by employing the NOAA-HYSPLIT air mass back trajectory analysis. Based on AE against AOD500 nm scatter plot and advection pathways followed five major aerosol types viz., continental average (CA), marine continental average (MCA), urban/industrial and biomass burning (UB), desert dust (DD) and indeterminate or mixed type (MT) have been identified. In winter, sector SE/E, a representative of air masses traversed over Bay of Bengal and Eastern continental Indian region has relatively small AOD (τpλ = 0.43 ± 0.13) and high AE (α = 1.19 ± 0.15). These values imply the presence of accumulation/sub-micron size anthropogenic aerosols. During pre-monsoon, aerosols from the NW/N sector have high AOD (τpλ = 0.61 ± 0.21), and low AE (α = 0.54 ± 0.14) indicating an increase in the loading of coarse-mode particles over Pune. Dominance of UB type in winter season for all the years (i.e. 2010-2013) may be attributed to both local/transported aerosols. During pre-monsoon seasons, MT is the dominant aerosol type followed by UB and DD, while the background aerosols are insignificant.

  5. Chemical and Trajectory Analysis of an Air Mass Plume from Asia

    NASA Astrophysics Data System (ADS)

    Guo, J. J.; Marrero, J. E.; Blake, D. R.

    2014-12-01

    Tracking the source of pollution events is important in understanding the transport of pollution plumes and impact on areas far from the source. Previous studies have shown that the rising contribution of Asian air pollution to the US has increased the number of days that pollution events exceed National Ambient Air Quality Standards (NAAQS). Whole air samples collected over the Edwards Air Force Base during a June 2014 NASA Student Airborne Research Program (SARP) flight exhibited enhancements in the concentrations of several compounds between 23-32 thousand feet. Chemical tracer analysis of these high altitude samples reveal that the air does not correspond to California emitted air. Chemical signatures in the plume, including high levels of OCS, chloroform, and methyl chloride, and low levels of methyl bromide, indicate that the plume was most heavily influence by coal combustion with contributions from biomass burning events from Asia. Low concentrations of ethene at the high altitude despite enhanced concentrations of ethane and ethyne suggest that this plume was aged. Further analysis of the plume using meteorological wind trajectories reveal that the plume had originated in China approximately 4-5 days prior. This is faster than results from previous studies that had found a Spring transport time of approximately 6 days.

  6. An air-mass trajectory study of the transport of radioactivity from Fukushima to Thessaloniki, Greece and Milan, Italy

    NASA Astrophysics Data System (ADS)

    Ioannidou, A.; Giannakaki, E.; Manolopoulou, M.; Stoulos, S.; Vagena, E.; Papastefanou, C.; Gini, L.; Manenti, S.; Groppi, F.

    2013-08-01

    Analyses of 131I, 137Cs and 134Cs in airborne aerosols were carried out in daily samples at two different sites of investigation: Thessaloniki, Greece (40° N) and Milan, Italy (45° N) after the Fukushima accident during the period of March-April, 2011. The radionuclide concentrations were determined and studied as a function of time. The 131I concentration in air over Milan and Thessaloniki peaked on April 3-4, 2011, with observed activities 467 μBq m-3 and 497 μBq m-3, respectively. The 134Cs/137Cs activity ratio values in air were around 1 in both regions, related to the burn-up history of the damaged nuclear fuel of the destroyed nuclear reactor. The high 131I/137Cs ratio, observed during the first days after the accident, followed by lower values during the following days, reflects not only the initial release ratio but also the different volatility, attachment and removal of the two isotopes during transportation due to their different physico-chemical properties. No artificial radionuclides could be detected in air after April 28, 2011 in both regions of investigation. The different maxima of airborne 131I and 134,137Cs in these two regions were related to long-range air mass transport from Japan, across the Pacific and to Central Europe. Analysis of backward trajectories was used to confirm the arrival of artificial radionuclides following atmospheric transport and processing. HYSPLIT backward trajectories were applied for the interpretation of activity variations of measured radionuclides.

  7. Origin of atmospheric aerosols at the Pierre Auger Observatory using studies of air mass trajectories in South America

    NASA Astrophysics Data System (ADS)

    Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antičić, T.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bardenet, R.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Foerster, N.; Fox, B. D.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giammarchi, M.; Giller, M.; Gitto, J.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kadija, K.; Kambeitz, O.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mićanović, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Nožka, L.; Oehlschläger, J.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Pȩkala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Pontz, M.; Porcelli, A.; Preda, T.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Rühle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Straub, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Taşcău, O.; Thao, N. T.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Tridapalli, D. B.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B. J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Curci, G.

    2014-11-01

    The Pierre Auger Observatory is making significant contributions towards understanding the nature and origin of ultra-high energy cosmic rays. One of its main challenges is the monitoring of the atmosphere, both in terms of its state variables and its optical properties. The aim of this work is to analyse aerosol optical depth τa(z) values measured from 2004 to 2012 at the observatory, which is located in a remote and relatively unstudied area of Pampa Amarilla, Argentina. The aerosol optical depth is in average quite low - annual mean τa(3.5 km) ∼ 0.04 - and shows a seasonal trend with a winter minimum - τa(3.5 km) ∼ 0.03 -, and a summer maximum - τa(3.5 km) ∼ 0.06 -, and an unexpected increase from August to September - τa(3.5 km) ∼ 0.055. We computed backward trajectories for the years 2005 to 2012 to interpret the air mass origin. Winter nights with low aerosol concentrations show air masses originating from the Pacific Ocean. Average concentrations are affected by continental sources (wind-blown dust and urban pollution), whilst the peak observed in September and October could be linked to biomass burning in the northern part of Argentina or air pollution coming from surrounding urban areas.

  8. Seasonal variability of tritium and ion concentrations in rain at Kumamoto, Japan and back-trajectory analysis of air mass

    SciTech Connect

    Momoshima, N.; Sugihara, S.; Toyoshima, T.; Nagao, Y.; Takahashi, M.; Nakamura, Y.

    2008-07-15

    Tritium and major ion concentrations in rain were analyzed in Kumamoto (Japan)) between 2001 and 2006 to examine present tritium concentration and seasonal variation. The average tritium concentration was 0.36 {+-} 0.19 Bq/L (n=104) and higher tritium concentrations were observed in spring than the other seasons. Among the ions, non-sea-salt (nss) SO{sub 4}{sup 2}'- showed higher concentration in winter while other ions did not show marked increase in winter. Based on the back-trajectory analyses of air masses, the increase in tritium concentrations in spring arises from downward movement of naturally produced tritium from stratosphere to troposphere, while the increase of the nss-SO{sub 4}{sup 2-} concentrations in winter is due to long range transport of pollutants from China to Japan. (authors)

  9. Rainwater monocarboxylic and dicarboxylic acid concentrations in southeastern North Carolina, USA, as a function of air-mass back-trajectory

    NASA Astrophysics Data System (ADS)

    Brooks Avery, G.; Kieber, Robert J.; Witt, Melanie; Willey, Joan D.

    Eight organic acids were measured in 111 rain events occurring between September 1996 and May 1998 in Wilmington, North Carolina. Formic and acetic acids were the most abundant comprising approximately 75% of the total molar quantity of organic acids. The annual volume-weighted concentrations of organic acids in order of decreasing abundance in rainwater was formic (9.9 μM), acetic (7.3 μM), oxalic (1.8 μM), lactic (1.3 μM), succinic (1.0 μM), malonic (0.7 μM), pyruvic (0.3 μM), and maleic (0.1 μM), with methanesulfonic and glyoxylic acids usually below their detection limit. Growing season back-trajectory data provided strong evidence that terrestrial organic acid sources dominated over marine sources. Air mass back-trajectory analysis indicated that during the growing season air mass origin had a consistent impact on concentrations of rainwater organic acids. Rain with continental back-trajectories coming from the west had the highest concentrations of organic acids while two predominately marine back-trajectories had the lowest concentrations. Concentrations of organic acids in non-growing season rain did not display a consistent pattern indicating variability in sources. Seasonality of individual organic acids for specific back-trajectories was most pronounced in terrestrial back-trajectories and least in the marine back-trajectories indicating that seasonality in rainwater organic acid concentrations is driven by variations in terrestrial sources. Formic to acetic acid ratios (F:A), previously an indicator of terrestrial versus marine sources of these organic acids, were similar for all back-trajectories reflecting anthropogenic impacts on F:A locally and regionally. The ratios of malonic to succinic acids (M:S), also an indicator of sources for these acids, indicated direct anthropogenic sources for terrestrial back-trajectories and secondary processes for marine back-trajectories.

  10. Back-trajectory modelling and DNA-based species-specific detection methods allow tracking of fungal spore transport in air masses.

    PubMed

    Grinn-Gofroń, Agnieszka; Sadyś, Magdalena; Kaczmarek, Joanna; Bednarz, Aleksandra; Pawłowska, Sylwia; Jedryczka, Malgorzata

    2016-11-15

    Recent advances in molecular detection of living organisms facilitate the introduction of novel methods to studies of the transport of fungal spores over large distances. Monitoring the migration of airborne fungi using microscope based spore identification is limited when different species produce very similar spores. In our study, DNA-based monitoring with the use of species-specific probes allowed us to track the aerial movements of two important fungal pathogens of oilseed rape (Brassica napus L.), i.e., Leptosphaeria maculans and Leptosphaeria biglobosa, which have identical spore shape and size. The fungi were identified using dual-labelled fluorescent probes that were targeted to a β-tubulin gene fragment of either Leptosphaeria species. Spore identification by Real-Time PCR techniques capable of detecting minute amounts of DNA of selected fungal species was combined with back-trajectory analysis, allowing the tracking of past movements of air masses using the Hybrid Single Particle Lagrangian Integrated Trajectory model. Over a study period spanning the previous decade (2006-2015) we investigated two specific events relating to the long distance transport of Leptosphaeria spp. spores to Szczecin in North-West Poland. Based on the above mentioned methods and the results obtained with the additional spore sampler located in nearby Szczecin, and operating at the ground level in an oilseed rape field, we have demonstrated that on both occasions the L. biglobosa spores originated from the Jutland Peninsula. This is the first successful attempt to combine analysis of back-trajectories of air masses with DNA-based identification of economically important pathogens of oilseed rape in Europe. In our studies, the timing of L. biglobosa ascospore dispersal in the air was unlikely to result in the infection of winter oilseed rape grown as a crop plant. However, the fungus could infect other host plants, such as vegetable brassicas, cruciferous weeds, spring rapeseed

  11. Back-trajectory modelling and DNA-based species-specific detection methods allow tracking of fungal spore transport in air masses.

    PubMed

    Grinn-Gofroń, Agnieszka; Sadyś, Magdalena; Kaczmarek, Joanna; Bednarz, Aleksandra; Pawłowska, Sylwia; Jedryczka, Malgorzata

    2016-11-15

    Recent advances in molecular detection of living organisms facilitate the introduction of novel methods to studies of the transport of fungal spores over large distances. Monitoring the migration of airborne fungi using microscope based spore identification is limited when different species produce very similar spores. In our study, DNA-based monitoring with the use of species-specific probes allowed us to track the aerial movements of two important fungal pathogens of oilseed rape (Brassica napus L.), i.e., Leptosphaeria maculans and Leptosphaeria biglobosa, which have identical spore shape and size. The fungi were identified using dual-labelled fluorescent probes that were targeted to a β-tubulin gene fragment of either Leptosphaeria species. Spore identification by Real-Time PCR techniques capable of detecting minute amounts of DNA of selected fungal species was combined with back-trajectory analysis, allowing the tracking of past movements of air masses using the Hybrid Single Particle Lagrangian Integrated Trajectory model. Over a study period spanning the previous decade (2006-2015) we investigated two specific events relating to the long distance transport of Leptosphaeria spp. spores to Szczecin in North-West Poland. Based on the above mentioned methods and the results obtained with the additional spore sampler located in nearby Szczecin, and operating at the ground level in an oilseed rape field, we have demonstrated that on both occasions the L. biglobosa spores originated from the Jutland Peninsula. This is the first successful attempt to combine analysis of back-trajectories of air masses with DNA-based identification of economically important pathogens of oilseed rape in Europe. In our studies, the timing of L. biglobosa ascospore dispersal in the air was unlikely to result in the infection of winter oilseed rape grown as a crop plant. However, the fungus could infect other host plants, such as vegetable brassicas, cruciferous weeds, spring rapeseed

  12. Air breathing engine/rocket trajectory optimization

    NASA Technical Reports Server (NTRS)

    Smith, V. K., III

    1979-01-01

    This research has focused on improving the mathematical models of the air-breathing propulsion systems, which can be mated with the rocket engine model and incorporated in trajectory optimization codes. Improved engine simulations provided accurate representation of the complex cycles proposed for advanced launch vehicles, thereby increasing the confidence in propellant use and payload calculations. The versatile QNEP (Quick Navy Engine Program) was modified to allow treatment of advanced turboaccelerator cycles using hydrogen or hydrocarbon fuels and operating in the vehicle flow field.

  13. PM2.5 chemical composition at a rural background site in Central Europe, including correlation and air mass back trajectory analysis

    NASA Astrophysics Data System (ADS)

    Schwarz, Jaroslav; Cusack, Michael; Karban, Jindřich; Chalupníčková, Eva; Havránek, Vladimír; Smolík, Jiří; Ždímal, Vladimír

    2016-07-01

    of fresh, local aerosol and aged, long-range transport aerosol. The influences of different air masses were also investigated. The lowest concentrations of PM2.5 were recorded under the influence of marine air masses from the NW, which were also marked by increased concentrations of marine aerosol. In contrast, the highest concentrations of PM2.5 and most major chemical components were measured during periods when continental easterly air masses were dominant.

  14. Effects of modeling errors on trajectory predictions in air traffic control automation

    NASA Technical Reports Server (NTRS)

    Jackson, Michael R. C.; Zhao, Yiyuan; Slattery, Rhonda

    1996-01-01

    Air traffic control automation synthesizes aircraft trajectories for the generation of advisories. Trajectory computation employs models of aircraft performances and weather conditions. In contrast, actual trajectories are flown in real aircraft under actual conditions. Since synthetic trajectories are used in landing scheduling and conflict probing, it is very important to understand the differences between computed trajectories and actual trajectories. This paper examines the effects of aircraft modeling errors on the accuracy of trajectory predictions in air traffic control automation. Three-dimensional point-mass aircraft equations of motion are assumed to be able to generate actual aircraft flight paths. Modeling errors are described as uncertain parameters or uncertain input functions. Pilot or autopilot feedback actions are expressed as equality constraints to satisfy control objectives. A typical trajectory is defined by a series of flight segments with different control objectives for each flight segment and conditions that define segment transitions. A constrained linearization approach is used to analyze trajectory differences caused by various modeling errors by developing a linear time varying system that describes the trajectory errors, with expressions to transfer the trajectory errors across moving segment transitions. A numerical example is presented for a complete commercial aircraft descent trajectory consisting of several flight segments.

  15. Second-stage trajectories of air-breathing space planes

    NASA Astrophysics Data System (ADS)

    Staufenbiel, R. W.

    1990-12-01

    Attention throughout the world has turned to the benefits that can be gained in space transportation by combining the features of aircraft and rockets. In the rocket-driven phase or stage, which follows the nearly horizontal air-breathing flight, a considerable change in the flight trajectory, a pullup maneuver, is necessary shortly before or after igniting the rocket engines. The change puts a burden on the first or the second stage and thereby reduces the payload. In this paper an optimal strategy for the rocket-propelled flight phase is developed that gives the smallest penalties on longitudinal acceleration and, therefore, on burnout mass. The strategy leads to a splitting of lift and thrust component normal to the flight direction. Two other control strategies are compared with the optimal procedure. Using a generic modeling of aerodynamic characteristics, the equations of motion are solved to assess the influence of initial conditions and of trajectory parameters on the burnout mass. Results of the study show the essential influence of the initial values of flight-path angle and Mach number on the rocket-propelled flight phase. Initial flight-path angle should not be lower than 5 deg. If a reasonable amount of payload and propellant for in-orbit operation should be carried, the dry-mass ratio of the second stage must come down to the range of 15 to 20, depending on the separation Mach number (5 to 6.5).

  16. Modified point mass trajectory simulation for base-burn projectiles

    NASA Astrophysics Data System (ADS)

    Lieske, R. F.; Danberg, J. E.

    1992-03-01

    An addition to the Modified Point Mass Trajectory Model for Rocket-Assisted Projectiles is presented for the exterior ballistic simulation of base-burn projectiles. The addition models the change in aerodynamic base-drag based on the change in base pressure due to the base-burn motor's ejection of hot gas into the wake of the projectile. The mass flow rate of the remaining fuel of the base-burn motor is modeled as a function of the instantaneous projectile spin rate and atmospheric air pressure. HAWK Doppler radar data collected at Yuma Proving Ground, Arizona, for the 155mm, M1864 base-burn projectile were used to verify the modeling approach for a variety of test conditions.

  17. Exploring Categorical Body Mass Index Trajectories in Elementary School Children

    ERIC Educational Resources Information Center

    Moreno-Black, Geraldine; Boles, Shawn; Johnson-Shelton, Deb; Evers, Cody

    2016-01-01

    Background: Studies of body mass index (BMI) change have focused on understanding growth trajectories from childhood to adolescence and adolescence to adulthood, but few have explored BMI trajectories solely in elementary (grades K-5) school children. This report complements these studies by exploring changes in obesity status using analytic…

  18. Air parcel trajectory dispersion near the tropical tropopause

    NASA Astrophysics Data System (ADS)

    Bergman, John W.; Jensen, Eric J.; Pfister, Leonhard; Bui, Thaopaul V.

    2016-04-01

    Dispersion of backward air parcel trajectories that are initially tightly grouped near the tropical tropopause is examined using three ensemble approaches: "RANWIND," in which different ensemble members use identical resolved wind fluctuations but different realizations of stochastic, multifractal simulations of unresolved winds; "PERTLOC," in which members use identical resolved wind fields but initial locations are perturbed 2° in latitude and longitude; and a multimodel ensemble ("MULTIMODEL") that uses identical initial conditions but different resolved wind fields and/or trajectory formulations. Comparisons among the approaches distinguish, to some degree, physical dispersion from that due to data uncertainty and the impacts of unresolved wind fluctuations from those of resolved variability. Dispersion rates are robust properties of trajectories near the tropical tropopause. Horizontal dispersion rates are typically ~3°/d, which is large enough to spread parcels throughout the tropics within typical tropical tropopause layer transport times (30-60 days) and underscores the importance of averaging large collections of trajectories to obtain reliable parcel source and pathway distributions. Vertical dispersion rates away from convection are ~2-3 hPa/d. Dispersion is primarily carried out by the resolved flow, and the RANWIND approach provides a plausible representation of actual trajectory dispersion rates, while PERTLOC provides a reasonable and inexpensive alternative to RANWIND. In contrast, dispersion from the MULTIMODEL calculations is important because it reflects systematic differences in resolved wind fields from different reanalysis data sets.

  19. Trajectory Specification for High-Capacity Air Traffic Control

    NASA Technical Reports Server (NTRS)

    Paielli, Russell A.

    2004-01-01

    In the current air traffic management system, the fundamental limitation on airspace capacity is the cognitive ability of human air traffic controllers to maintain safe separation with high reliability. The doubling or tripling of airspace capacity that will be needed over the next couple of decades will require that tactical separation be at least partially automated. Standardized conflict-free four-dimensional trajectory assignment will be needed to accomplish that objective. A trajectory specification format based on the Extensible Markup Language is proposed for that purpose. This format can be used to downlink a trajectory request, which can then be checked on the ground for conflicts and approved or modified, if necessary, then uplinked as the assigned trajectory. The horizontal path is specified as a series of geodetic waypoints connected by great circles, and the great-circle segments are connected by turns of specified radius. Vertical profiles for climb and descent are specified as low-order polynomial functions of along-track position, which is itself specified as a function of time. Flight technical error tolerances in the along-track, cross-track, and vertical axes define a bounding space around the reference trajectory, and conformance will guarantee the required separation for a period of time known as the conflict time horizon. An important safety benefit of this regimen is that the traffic will be able to fly free of conflicts for at least several minutes even if all ground systems and the entire communication infrastructure fail. Periodic updates in the along-track axis will adjust for errors in the predicted along-track winds.

  20. Trajectory Specification for Automation of Terminal Air Traffic Control

    NASA Technical Reports Server (NTRS)

    Paielli, Russell A.

    2016-01-01

    "Trajectory specification" is the explicit bounding and control of aircraft tra- jectories such that the position at each point in time is constrained to a precisely defined volume of space. The bounding space is defined by cross-track, along-track, and vertical tolerances relative to a reference trajectory that specifies position as a function of time. The tolerances are dynamic and will be based on the aircraft nav- igation capabilities and the current traffic situation. A standard language will be developed to represent these specifications and to communicate them by datalink. Assuming conformance, trajectory specification can guarantee safe separation for an arbitrary period of time even in the event of an air traffic control (ATC) sys- tem or datalink failure, hence it can help to achieve the high level of safety and reliability needed for ATC automation. As a more proactive form of ATC, it can also maximize airspace capacity and reduce the reliance on tactical backup systems during normal operation. It applies to both enroute airspace and the terminal area around airports, but this paper focuses on arrival spacing in the terminal area and presents ATC algorithms and software for achieving a specified delay of runway arrival time.

  1. Trajectory Simulation of Meteors Assuming Mass Loss and Fragmentation

    NASA Technical Reports Server (NTRS)

    Allen, Gary A., Jr.; Prabhu, Dinesh K.; Saunders, David A

    2015-01-01

    Program used to simulate atmospheric flight trajectories of entry capsules [1] Includes models of atmospheres of different planetary destinations - Earth, Mars, Venus, Jupiter, Saturn, Uranus, Titan, ... Solves 3-­-degrees of freedom (3DoF) equations for a single body treated as a point mass. Also supports 6-DoF trajectory simula4on and Monte Carlo analyses. Uses Fehlberg-­-Runge-­-Kuna (4th-5th order) time integraion with automaic step size control. Includes rotating spheroidal planet with gravitational field having a J2 harmonic. Includes a variety of engineering aerodynamic and heat flux models. Capable of specifying events - heatshield jettison, parachute deployment, etc. - at predefined altitudes or Mach number. Has material thermal response models of typical aerospace materials integrated.

  2. Assessment of potential long-range transport of particulate air pollution using trajectory modeling and monitoring data

    NASA Astrophysics Data System (ADS)

    Pongkiatkul, Prapat; Kim Oanh, Nguyen Thi

    2007-07-01

    Quantification of the long-range transport (LRT) contribution to ambient air pollution levels at a location is a challenging task and is normally done with a high uncertainty. In the lack of accurate emission data over the large regional domain for dispersion modeling, this study attempts to use both trajectory analysis and monitoring data to assess the potential contribution of LRT to particulate air pollution (PM) in the Bangkok Metropolitan Region (BMR). The 10-day backward trajectories of air masses arriving at BMR from January 2002 to December 2004 were determined using Hybrid Single-Particle Langrangian Integrated Trajectory model version 4 (HYSPLIT4) and were categorized by k-means clustering into 6 clusters. Subsequently, PM levels in the BMR associated with each air mass cluster during this period were analyzed. Clusters 1 and 6 were observed with the highest and 2nd highest average PM 10 and PM 2.5 levels in the BMR, respectively, which commonly have a longer air mass pathway over populated South East Asia (SEA). The third highest PM levels were associated with air masses from the east (clusters 2 and 5), which enter the BMR via the Gulf of Thailand without passing the SEA regions. The other two clusters (3 and 4) are characterized with a long pathway of air masses over the Indian Ocean and the lowest PM levels. High PM days, which are defined based on the spatial coverage of high PM levels in the BMR, were identified and analyzed for the possibility of long-range transport contribution of PM. The potential source contribution function (PSCF) and air mass trajectories show that on high PM day, the air masses commonly originated and passed over populated regions before arriving at the BMR, which suggests a possible LRT contribution. Considerations are made for surface ozone, SO 42-/SO 2 and average SO 2, PM 2.5/PM 10, and weekday-weekend traffic emission within each air mass trajectory cluster to reveal the possible LRT contribution.

  3. Conflict-free trajectory planning for air traffic control automation

    NASA Technical Reports Server (NTRS)

    Slattery, Rhonda; Green, Steve

    1994-01-01

    As the traffic demand continues to grow within the National Airspace System (NAS), the need for long-range planning (30 minutes plus) of arrival traffic increases greatly. Research into air traffic control (ATC) automation at ARC has led to the development of the Center-TRACON Automation System (CTAS). CTAS determines optimum landing schedules for arrival traffic and assists controllers in meeting those schedules safely and efficiently. One crucial element in the development of CTAS is the capability to perform long-range (20 minutes) and short-range (5 minutes) conflict prediction and resolution once landing schedules are determined. The determination of conflict-free trajectories within the Center airspace is particularly difficult because of large variations in speed and altitude. The paper describes the current design and implementation of the conflict prediction and resolution tools used to generate CTAS advisories in Center airspace. Conflict criteria (separation requirements) are defined and the process of separation prediction is described. The major portion of the paper will describe the current implementation of CTAS conflict resolution algorithms in terms of the degrees of freedom for resolutions as well as resolution search techniques. The tools described in this paper have been implemented in a research system designed to rapidly develop and evaluate prototype concepts and will form the basis for an operational ATC automation system.

  4. FORECASTING A CORONAL MASS EJECTION'S ALTERED TRAJECTORY: ForeCAT

    SciTech Connect

    Kay, C.; Opher, M.; Evans, R. M.

    2013-09-20

    To predict whether a coronal mass ejection (CME) will impact Earth, the effects of the background on the CME's trajectory must be taken into account. We develop a model, ForeCAT (Forecasting a CME's Altered Trajectory), of CME deflection due to magnetic forces. ForeCAT includes CME expansion, a three-part propagation model, and the effects of drag on the CME's deflection. Given the background solar wind conditions, the launch site of the CME, and the properties of the CME (mass, final propagation speed, initial radius, and initial magnetic strength), ForeCAT predicts the deflection of the CME. Two different magnetic backgrounds are considered: a scaled background based on type II radio burst profiles and a potential field source surface (PFSS) background. For a scaled background where the CME is launched from an active region located between a coronal hole and streamer region, the strong magnetic gradients cause a deflection of 8. Degree-Sign 1 in latitude and 26. Degree-Sign 4 in longitude for a 10{sup 15} g CME propagating out to 1 AU. Using the PFSS background, which captures the variation of the streamer belt (SB) position with height, leads to a deflection of 1. Degree-Sign 6 in latitude and 4. Degree-Sign 1 in longitude for the control case. Varying the CME's input parameters within observed ranges leads to the majority of CMEs reaching the SB within the first few solar radii. For these specific backgrounds, the SB acts like a potential well that forces the CME into an equilibrium angular position.

  5. Tracking hazardous air pollutants from a refinery fire by applying on-line and off-line air monitoring and back trajectory modeling.

    PubMed

    Shie, Ruei-Hao; Chan, Chang-Chuan

    2013-10-15

    The air monitors used by most regulatory authorities are designed to track the daily emissions of conventional pollutants and are not well suited for measuring hazardous air pollutants that are released from accidents such as refinery fires. By applying a wide variety of air-monitoring systems, including on-line Fourier transform infrared spectroscopy, gas chromatography with a flame ionization detector, and off-line gas chromatography-mass spectrometry for measuring hazardous air pollutants during and after a fire at a petrochemical complex in central Taiwan on May 12, 2011, we were able to detect significantly higher levels of combustion-related gaseous and particulate pollutants, refinery-related hydrocarbons, and chlorinated hydrocarbons, such as 1,2-dichloroethane, vinyl chloride monomer, and dichloromethane, inside the complex and 10 km downwind from the fire than those measured during the normal operation periods. Both back trajectories and dispersion models further confirmed that high levels of hazardous air pollutants in the neighboring communities were carried by air mass flown from the 22 plants that were shut down by the fire. This study demonstrates that hazardous air pollutants from industrial accidents can successfully be identified and traced back to their emission sources by applying a timely and comprehensive air-monitoring campaign and back trajectory air flow models. PMID:23912073

  6. Antibiotic Use and Childhood Body Mass Index Trajectory

    PubMed Central

    Schwartz, Brian S.; Pollak, Jonathan; Bailey-Davis, Lisa; Hirsch, Annemarie G.; Cosgrove, Sara E.; Nau, Claudia; Kress, Amii M.; Glass, Thomas A.; Bandeen-Roche, Karen

    2015-01-01

    Background/Objectives Antibiotics are commonly prescribed for children. Use of antibiotics early in life has been linked to weight gain but there are no large-scale, population-based, longitudinal studies of the full age range among mainly healthy children. Subjects/Methods We used electronic health record data on 163,820 children aged 3-18 years and mixed effects linear regression to model associations of antibiotic orders with growth curve trajectories of annual body mass index (BMI) controlling for confounders. Models evaluated three kinds of antibiotic associations – reversible (time-varying indicator for an order in year before each BMI), persistent (time-varying cumulative orders up to BMIj), and progressive (cumulative orders up to prior BMI [BMIj-1]) – and whether these varied by age. Results Among 142,824 children under care in the prior year, a reversible association was observed and this short-term BMI gain was modified by age (p < 0.001); effect size peaked in mid-teen years. A persistent association was observed and this association was stronger with increasing age (p < 0.001). The addition of the progressive association among children with at least three BMIs (n = 79,752) revealed that higher cumulative orders were associated with progressive weight gain; this did not vary by age. Among children with an antibiotic order in the prior year and at least seven lifetime orders, antibiotics (all classes combined) were associated with an average weight gain of approximately 1.4 kg at age 15 years. When antibiotic classes were evaluated separately, the largest weight gain at 15 years was associated with macrolide use. Conclusions We found evidence of reversible, persistent, and progressive effects of antibiotic use on BMI trajectories, with different effects by age, among mainly healthy children. The results suggest that antibiotic use may influence weight gain throughout childhood and not just during the earliest years as has been the primary focus of

  7. Improving stable isotope-based reconstructions of Sierra Nevada paleotopography using insights from regional air parcel trajectories

    NASA Astrophysics Data System (ADS)

    Lechler, A.; Galewsky, J.

    2012-12-01

    The geodynamic evolution of the Sierra Nevada Mountains of the western US remains subject to debate due to the lack of consensus on the Cenozoic paleoelevation history of the range. The majority of recent studies attempting to quantify the surface uplift history of the Sierra Nevada rely on stable isotope paleoaltimetry methods that often implicitly assume that atmospheric flow interactions with topography can be simply modeled as a Rayleigh distillation process in which air mass trajectories ascend and rainout heavy isotopologues of water (18O and D) across topographic barriers relatively unimpeded. Accordingly, stable isotope paleoaltimetry studies commonly target leeward side paleo-meteoric water proxies to constrain paleotopography of the windward barrier. We present a modern (1979 - 2010) air parcel trajectory analysis using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model that shows that the fundamental assumptions of stable isotope paleoaltimetry are often violated in the Sierra Nevada region. Trajectory analysis indicates that westerly air masses are frequently orographically blocked by and redirected around the higher elevations (> 2.5 km) of the Sierra Nevada. As a result, trajectories reaching the Sierran lee commonly travel around, rather than over, the highest range elevations. These blocking and redirection effects are particularly pronounced for leeward sites that are distal (> 150 km) from the Sierran crest but are also evident in trajectory patterns for both windward and proximal leeward locations in the northern Sierra Nevada. In addition, trajectory patterns indicate that much of the Sierran lee receives a non-negligible proportion of annual precipitation from summer storm systems sourced in the subtropical Pacific Ocean and Gulf of California that have little to no interaction with Sierran topography. This trajectory analysis highlights the complexity of orographic precipitation patterns and processes in the Sierra

  8. The Impact of Trajectory Prediction Uncertainty on Air Traffic Controller Performance and Acceptability

    NASA Technical Reports Server (NTRS)

    Mercer, Joey S.; Bienert, Nancy; Gomez, Ashley; Hunt, Sarah; Kraut, Joshua; Martin, Lynne; Morey, Susan; Green, Steven M.; Prevot, Thomas; Wu, Minghong G.

    2013-01-01

    A Human-In-The-Loop air traffic control simulation investigated the impact of uncertainties in trajectory predictions on NextGen Trajectory-Based Operations concepts, seeking to understand when the automation would become unacceptable to controllers or when performance targets could no longer be met. Retired air traffic controllers staffed two en route transition sectors, delivering arrival traffic to the northwest corner-post of Atlanta approach control under time-based metering operations. Using trajectory-based decision-support tools, the participants worked the traffic under varying levels of wind forecast error and aircraft performance model error, impacting the ground automations ability to make accurate predictions. Results suggest that the controllers were able to maintain high levels of performance, despite even the highest levels of trajectory prediction errors.

  9. Generalized flyby trajectories around elongated minor celestial bodies as a rotating mass dipole

    NASA Astrophysics Data System (ADS)

    Zeng, Xiangyuan; Fang, Baodong; Li, Junfeng; Yu, Yang

    2016-06-01

    The aim of this paper is to understand the common characteristics of the generalized flyby trajectory around natural elongated bodies. Such flyby trajectories provide a short-term mechanism to clear away vicinal objects or temporally capture ejecta into circling orbits. The gravitational potential of elongated bodies is described by a unified approximate model, i.e., the rotating mass dipole which is two point masses connected with a constant massless rod. The energy power is used to illustrate the flyby effect in terms of the instantaneous orbital energy. The essential of the single flyby trajectory is studied analytically, and the relationship between the flyby trajectory and its Jacobi integral is also illustrated. Sample trajectories are given to show the variational trend of the energy increment with respect to different orbital periapsides. The distribution of natural ejecting orbits is presented by varying the parameters of the approximate model.

  10. Separating the Air Quality Impact of a Major Highway and Nearby Sources by Nonparametric Trajectory Analysis

    EPA Science Inventory

    Nonparametric Trajectory Analysis (NTA), a receptor-oriented model, was used to assess the impact of local sources of air pollution at monitoring sites located adjacent to highway I-15 in Las Vegas, NV. Measurements of black carbon, carbon monoxide, nitrogen oxides, and sulfur di...

  11. Intermediate-mass-ratio black hole binaries. II. Modeling trajectories and gravitational waveforms

    NASA Astrophysics Data System (ADS)

    Nakano, Hiroyuki; Zlochower, Yosef; Lousto, Carlos O.; Campanelli, Manuela

    2011-12-01

    We revisit the scenario of small-mass-ratio (q) black hole binaries; performing new, more accurate, simulations of mass ratios 10:1 and 100:1 for initially nonspinning black holes. We propose fitting functions for the trajectories of the two black holes as a function of time and mass ratio (in the range 1/100≤q≤1/10) that combine aspects of post-Newtonian trajectories at smaller orbital frequencies and plunging geodesics at larger frequencies. We then use these trajectories to compute waveforms via black hole perturbation theory. Using the advanced LIGO noise curve, we see a match of ˜99.5% for the leading (ℓ,m)=(2,2) mode between the numerical relativity and perturbative waveforms. Nonleading modes have similarly high matches. We thus prove the feasibility of efficiently generating a bank of gravitational waveforms in the intermediate-mass-ratio regime using only a sparse set of full numerical simulations.

  12. Using Lidar, in-situ measurements and Trajectory Analysis to observe air pollution in Beijing, 2014

    NASA Astrophysics Data System (ADS)

    Chen, Zhenyi; Liu, Wenqing; Liu, Jianguo; Zhang, Tianshu; Dong, Yunsheng

    2016-06-01

    We present combined Mie lidar, ozone lidar and wide-range particle spectrometer observations that were carried out in Beijing, north China during two periods—one haze period before the Asia-Pacific Economic Cooperation (APEC) meeting and one moderate pollution period during the meeting in 2014. High extinction coefficient, moderate ozone concentration and variable particle number concentration were obtained throughout the first haze observation period. The mean extinction coefficients in the two pollution periods were 0.52 km-1 and 0.23 km-1, respectively, at 532 nm. The ozone concentration during the first haze phase was more various with higher average value of 49 ppb compared to that in the second pollution observations (32 ppb). The comparison of aerosols and ozone in different heights indicate different pollution sources and complicated ozone process of generation and disappearance. The four-day back trajectories from a HYSPLIT model indicate that the air masses in the lower boundary layer were advected from the densely populated south regions of China and the long pollution transportation passing through northern China.

  13. Uncertainty and dispersion in air parcel trajectories near the tropical tropopause

    NASA Astrophysics Data System (ADS)

    Bergman, John; Jensen, Eric; Pfister, Leonhard; Bui, Thoapaul

    2016-04-01

    The Tropical Tropopause Layer (TTL) is important as the gateway to the stratosphere for chemical constituents produced at the Earth's surface. As such, understanding the processes that transport air through the upper tropical troposphere is important for a number of current scientific issues such as the impact of stratospheric water vapor on the global radiative budget and the depletion of ozone by both anthropogenically- and naturally-produced halocarbons. Compared to the lower troposphere, transport in the TTL is relatively unaffected by turbulent motion. Consequently, Lagrangian particle models are thought to provide reasonable estimates of parcel pathways through the TTL. However, there are complications that make trajectory analyses difficult to interpret; uncertainty in the wind data used to drive these calculations and trajectory dispersion being among the most important. These issues are examined using ensembles of backward air parcel trajectories that are initially tightly grouped near the tropical tropopause using three approaches: A Monte Carlo ensemble, in which different members use identical resolved wind fluctuations but different realizations of stochastic, multi-fractal simulations of unresolved winds, perturbed initial location ensembles, in which members use identical resolved wind fields but initial locations are displaced 2° in latitude and longitude, and a multi-model ensemble that uses identical initial conditions but different resolved wind fields and/or trajectory formulations. Comparisons among the approaches distinguish, to some degree, physical dispersion from that due to data uncertainty and the impact of unresolved wind fluctuations from that of resolved variability.

  14. Trajectory-capture cell instrumentation for measurement of dust particle mass, velocity and trajectory, and particle capture

    NASA Technical Reports Server (NTRS)

    Simpson, J. A.; Tuzzolino, A. J.

    1989-01-01

    The development of the polyvinylidene fluoride (PVDF) dust detector for space missions--such as the Halley Comet Missions where the impact velocity was very high as well as for missions where the impact velocity is low was extended to include: (1) the capability for impact position determination - i.e., x,y coordinate of impact; and (2) the capability for particle velocity determination using two thin PVDF sensors spaced a given distance apart - i.e., by time-of-flight. These developments have led to space flight instrumentation for recovery-type missions, which will measure the masses (sizes), fluxes and trajectories of incoming dust particles and will capture the dust material in a form suitable for later Earth-based laboratory measurements. These laboratory measurements would determine the elemental, isotopic and mineralogical properties of the captured dust and relate these to possible sources of the dust material (i.e., comets, asteroids), using the trajectory information. The instrumentation described here has the unique advantages of providing both orbital characteristics and physical and chemical properties--as well as possible origin--of incoming dust.

  15. A Near-Term Concept for Trajectory Based Operations with Air/Ground Data Link Communication

    NASA Technical Reports Server (NTRS)

    McNally, David; Mueller, Eric; Thipphavong, David; Paielli, Russell; Cheng, Jinn-Hwei; Lee, Chuhan; Sahlman, Scott; Walton, Joe

    2010-01-01

    An operating concept and required system components for trajectory-based operations with air/ground data link for today's en route and transition airspace is proposed. Controllers are fully responsible for separation as they are today, and no new aircraft equipage is required. Trajectory automation computes integrated solutions to problems like metering, weather avoidance, traffic conflicts and the desire to find and fly more time/fuel efficient flight trajectories. A common ground-based system supports all levels of aircraft equipage and performance including those equipped and not equipped for data link. User interface functions for the radar controller's display make trajectory-based clearance advisories easy to visualize, modify if necessary, and implement. Laboratory simulations (without human operators) were conducted to test integrated operation of selected system components with uncertainty modeling. Results are based on 102 hours of Fort Worth Center traffic recordings involving over 37,000 individual flights. The presence of uncertainty had a marginal effect (5%) on minimum-delay conflict resolution performance, and windfavorable routes had no effect on detection and resolution metrics. Flight plan amendments and clearances were substantially reduced compared to today s operations. Top-of-descent prediction errors are the largest cause of failure indicating that better descent predictions are needed to reliably achieve fuel-efficient descent profiles in medium to heavy traffic. Improved conflict detections for climbing flights could enable substantially more continuous climbs to cruise altitude. Unlike today s Conflict Alert, tactical automation must alert when an altitude amendment is entered, but before the aircraft starts the maneuver. In every other failure case tactical automation prevented losses of separation. A real-time prototype trajectory trajectory-automation system is running now and could be made ready for operational testing at an en route

  16. The Use of Red Green Blue (RGB) Air Mass Imagery to Investigate the Role of Stratospheric Air in a Non-Convective Wind Event

    NASA Technical Reports Server (NTRS)

    Berndt, Emily; Zavodsky, Bradley; Molthan, Andrew; Jedlovec, Gary

    2013-01-01

    AIRS ozone and model PV analysis confirm the stratospheric air in RGB Air Mass imagery. Trajectories confirm winds south of the low were distinct from CCB driven winds. Cross sections connect the tropopause fold, downward motion, and high nearsurface winds. Comparison to conceptual models show Shapiro-Keyser features and sting jet characteristics were observed in a storm that impacted the U.S. East Coast. RGB Air Mass imagery can be used to identify stratospheric air and regions susceptible to tropopause folding and attendant non-convective winds.

  17. Trajectory Assessment and Modification Tools for Next Generation Air Traffic Management Operations

    NASA Technical Reports Server (NTRS)

    Brasil, Connie; Lee, Paul; Mainini, Matthew; Lee, Homola; Lee, Hwasoo; Prevot, Thomas; Smith, Nancy

    2011-01-01

    This paper reviews three Next Generation Air Transportation System (NextGen) based high fidelity air traffic control human-in-the-loop (HITL) simulations, with a focus on the expected requirement of enhanced automated trajectory assessment and modification tools to support future air traffic flow management (ATFM) planning positions. The simulations were conducted at the National Aeronautics and Space Administration (NASA) Ames Research Centers Airspace Operations Laboratory (AOL) in 2009 and 2010. The test airspace for all three simulations assumed the mid-term NextGenEn-Route high altitude environment utilizing high altitude sectors from the Kansas City and Memphis Air Route Traffic Control Centers. Trajectory assessment, modification and coordination decision support tools were developed at the AOL in order to perform future ATFM tasks. Overall tool usage results and user acceptability ratings were collected across three areas of NextGen operatoins to evaluate the tools. In addition to the usefulness and usability feedback, feasibility issues, benefits, and future requirements were also addressed. Overall, the tool sets were rated very useful and usable, and many elements of the tools received high scores and were used frequently and successfully. Tool utilization results in all three HITLs showed both user and system benefits including better airspace throughput, reduced controller workload, and highly effective communication protocols in both full Data Comm and mixed-equipage environments.

  18. PVDF flux/mass/velocity/trajectory systems and their applications in space

    NASA Technical Reports Server (NTRS)

    Tuzzolino, Anthony J.

    1994-01-01

    The current status of the University of Chicago Polyvinylidene Fluoride (PVDF) flux/mass/velocity/trajectory instrumentation is summarized. The particle response and thermal stability characteristics of pure PVDF and PVDF copolymer sensors are described, as well as the characteristics of specially constructed two-dimensional position-sensing PVDF sensors. The performance of high-flux systems and of velocity/trajectory systems using these sensors is discussed, and the objectives and designs of a PVDF velocity/trajectory dust instrument for launch on the Advanced Research and Global Observation Satellite (ARGOS) in 1995 and of a high-flux dust instrument for launch on the Cassini spacecraft to Saturn in 1997 are summarized.

  19. Parenting Styles and Body Mass Index Trajectories From Adolescence to Adulthood

    PubMed Central

    Fuemmeler, Bernard F.; Yang, Chongming; Costanzo, Phil; Hoyle, Rick H.; Ph.D.; Siegler, Ilene C.; Williams, Redford B.; Østbye, Truls

    2013-01-01

    Objective Parenting styles such as authoritarian, disengaged, or permissive are thought to be associated with greater adolescent obesity risk than an authoritative style. This study assessed the relationship between parenting styles and changes in body mass index (BMI) from adolescence to young adulthood. Methods The study included self-reported data from adolescents in the National Longitudinal Study of Adolescent Health. Factor mixture modeling, a data-driven approach, was used to classify participants into parenting style groups based on measures of acceptance and control. Latent growth modeling (LGM) identified patterns of developmental changes in BMI. After a number of potential cofounders were controlled for, parenting style variables were entered as predictors of BMI trajectories. Analyses were also conducted for males and females of three racial/ethnic groups (Hispanic, black, white) to assess whether parenting styles were differentially associated with BMI trajectories in these 6 groups. Results Parenting styles were classified into 4 groups: authoritarian, disengaged, permissive, and balanced. Compared with the balanced parenting style, authoritarian and disengaged parenting styles were associated with a less steep average BMI increase (linear slope) over time, but also less leveling off (quadratic) of BMI over time. Differences in BMI trajectories were observed for various genders and races, but the differences did not reach statistical significance. Conclusions Adolescents who reported having parents with authoritarian or disengaged parenting styles had greater increases in BMI as they transitioned to young adulthood despite having a lower BMI trajectory through adolescence. PMID:22545979

  20. The Effective Mass of a Ball in the Air

    ERIC Educational Resources Information Center

    Messer, J.; Pantaleone, J.

    2010-01-01

    The air surrounding a projectile affects the projectile's motion in three very different ways: the drag force, the buoyant force, and the added mass. The added mass is an increase in the projectile's inertia from the motion of the air around it. Here we experimentally measure the added mass of a spherical projectile in air. The results agree well…

  1. Estimation of Center of Mass Trajectory using Wearable Sensors during Golf Swing.

    PubMed

    Najafi, Bijan; Lee-Eng, Jacqueline; Wrobel, James S; Goebel, Ruben

    2015-06-01

    This study suggests a wearable sensor technology to estimate center of mass (CoM) trajectory during a golf swing. Groups of 3, 4, and 18 participants were recruited, respectively, for the purpose of three validation studies. Study 1 examined the accuracy of the system to estimate a 3D body segment angle compared to a camera-based motion analyzer (Vicon®). Study 2 assessed the accuracy of three simplified CoM trajectory models. Finally, Study 3 assessed the accuracy of the proposed CoM model during multiple golf swings. A relatively high agreement was observed between wearable sensors and the reference (Vicon®) for angle measurement (r > 0.99, random error <1.2° (1.5%) for anterior-posterior; <0.9° (2%) for medial-lateral; and <3.6° (2.5%) for internal-external direction). The two-link model yielded a better agreement with the reference system compared to one-link model (r > 0.93 v. r = 0.52, respectively). On the same note, the proposed two-link model estimated CoM trajectory during golf swing with relatively good accuracy (r > 0.9, A-P random error <1cm (7.7%) and <2cm (10.4%) for M-L). The proposed system appears to accurately quantify the kinematics of CoM trajectory as a surrogate of dynamic postural control during an athlete's movement and its portability, makes it feasible to fit the competitive environment without restricting surface type. Key pointsThis study demonstrates that wearable technology based on inertial sensors are accurate to estimate center of mass trajectory in complex athletic task (e.g., golf swing)This study suggests that two-link model of human body provides optimum tradeoff between accuracy and minimum number of sensor module for estimation of center of mass trajectory in particular during fast movements.Wearable technologies based on inertial sensors are viable option for assessing dynamic postural control in complex task outside of gait laboratory and constraints of cameras, surface, and base of support.

  2. Estimation of Center of Mass Trajectory using Wearable Sensors during Golf Swing

    PubMed Central

    Najafi, Bijan; Lee-Eng, Jacqueline; Wrobel, James S.; Goebel, Ruben

    2015-01-01

    This study suggests a wearable sensor technology to estimate center of mass (CoM) trajectory during a golf swing. Groups of 3, 4, and 18 participants were recruited, respectively, for the purpose of three validation studies. Study 1 examined the accuracy of the system to estimate a 3D body segment angle compared to a camera-based motion analyzer (Vicon®). Study 2 assessed the accuracy of three simplified CoM trajectory models. Finally, Study 3 assessed the accuracy of the proposed CoM model during multiple golf swings. A relatively high agreement was observed between wearable sensors and the reference (Vicon®) for angle measurement (r > 0.99, random error <1.2° (1.5%) for anterior-posterior; <0.9° (2%) for medial-lateral; and <3.6° (2.5%) for internal-external direction). The two-link model yielded a better agreement with the reference system compared to one-link model (r > 0.93 v. r = 0.52, respectively). On the same note, the proposed two-link model estimated CoM trajectory during golf swing with relatively good accuracy (r > 0.9, A-P random error <1cm (7.7%) and <2cm (10.4%) for M-L). The proposed system appears to accurately quantify the kinematics of CoM trajectory as a surrogate of dynamic postural control during an athlete’s movement and its portability, makes it feasible to fit the competitive environment without restricting surface type. Key points This study demonstrates that wearable technology based on inertial sensors are accurate to estimate center of mass trajectory in complex athletic task (e.g., golf swing) This study suggests that two-link model of human body provides optimum tradeoff between accuracy and minimum number of sensor module for estimation of center of mass trajectory in particular during fast movements. Wearable technologies based on inertial sensors are viable option for assessing dynamic postural control in complex task outside of gait laboratory and constraints of cameras, surface, and base of support. PMID:25983585

  3. Estimation of Center of Mass Trajectory using Wearable Sensors during Golf Swing.

    PubMed

    Najafi, Bijan; Lee-Eng, Jacqueline; Wrobel, James S; Goebel, Ruben

    2015-06-01

    This study suggests a wearable sensor technology to estimate center of mass (CoM) trajectory during a golf swing. Groups of 3, 4, and 18 participants were recruited, respectively, for the purpose of three validation studies. Study 1 examined the accuracy of the system to estimate a 3D body segment angle compared to a camera-based motion analyzer (Vicon®). Study 2 assessed the accuracy of three simplified CoM trajectory models. Finally, Study 3 assessed the accuracy of the proposed CoM model during multiple golf swings. A relatively high agreement was observed between wearable sensors and the reference (Vicon®) for angle measurement (r > 0.99, random error <1.2° (1.5%) for anterior-posterior; <0.9° (2%) for medial-lateral; and <3.6° (2.5%) for internal-external direction). The two-link model yielded a better agreement with the reference system compared to one-link model (r > 0.93 v. r = 0.52, respectively). On the same note, the proposed two-link model estimated CoM trajectory during golf swing with relatively good accuracy (r > 0.9, A-P random error <1cm (7.7%) and <2cm (10.4%) for M-L). The proposed system appears to accurately quantify the kinematics of CoM trajectory as a surrogate of dynamic postural control during an athlete's movement and its portability, makes it feasible to fit the competitive environment without restricting surface type. Key pointsThis study demonstrates that wearable technology based on inertial sensors are accurate to estimate center of mass trajectory in complex athletic task (e.g., golf swing)This study suggests that two-link model of human body provides optimum tradeoff between accuracy and minimum number of sensor module for estimation of center of mass trajectory in particular during fast movements.Wearable technologies based on inertial sensors are viable option for assessing dynamic postural control in complex task outside of gait laboratory and constraints of cameras, surface, and base of support. PMID:25983585

  4. Prospective trajectories of posttraumatic stress in college women following a campus mass shooting.

    PubMed

    Orcutt, Holly K; Bonanno, George A; Hannan, Susan M; Miron, Lynsey R

    2014-06-01

    In a sample with known levels of preshooting posttraumatic stress (PTS) symptoms, we examined the impact of a campus mass shooting on trajectories of PTS in the 31 months following the shooting using latent growth mixture modeling. Female students completed 7 waves of a longitudinal study (sample sizes ranged from 812 to 559). We identified 4 distinct trajectories (n = 660): (a) minimal impact-resilience (60.9%), (b) high impact-recovery (29.1%), (c) moderate impact-moderate symptoms (8.2%), and (d) chronic dysfunction (1.8%). Individuals in each trajectory class remained at or returned to preshooting levels of PTS approximately 6 months postshooting. The minimal impact-resilience class reported less prior trauma exposure (η(2) = .13), less shooting exposure (η(2) = .07), and greater emotion regulation skills than all other classes (η(2) > .30). The chronic dysfunction class endorsed higher rates of experiential avoidance prior to the shooting than the minimal-impact resilient and high impact-recovery classes (η(2) = .15), as well as greater shooting exposure than the high impact-recovery class (η(2) = .07). Findings suggest that preshooting functioning and emotion regulation distinguish between those who experience prolonged distress following mass violence and those who gradually recover.

  5. Gender, stress in childhood and adulthood, and trajectories of change in body mass.

    PubMed

    Liu, Hui; Umberson, Debra

    2015-08-01

    Despite substantial evidence of the linkage between stress and weight change, previous studies have not considered how stress trajectories that begin in childhood and fluctuate throughout adulthood may work together to have long-term consequences for weight change. Working from a stress and life course perspective, we investigate the linkages between childhood stress, adulthood stress and trajectories of change in body mass (i.e., Body Mass Index, BMI) over time, with attention to possible gender variation in these processes. Data are drawn from a national longitudinal survey of the Americans' Changing Lives (N = 3617). Results from growth curve analyses suggest that both women and men who experienced higher levels of childhood stress also report higher levels of stress in adulthood. At the beginning of the study period, higher levels of adulthood stress are related to greater BMI for women but not men. Moreover, women who experienced higher levels of childhood stress gained weight more rapidly throughout the 15-year study period than did women who experienced less childhood stress, but neither childhood nor adulthood stress significantly modified men's BMI trajectories. These findings add to our understanding of how childhood stress-a more important driver of long-term BMI increase than adult stress-reverberates throughout the life course to foster cumulative disadvantage in body mass, and how such processes differ for men and women. Results highlight the importance of considering sex-specific social contexts of early childhood in order to design effective clinical programs that prevent or treat overweight and obesity later in life.

  6. Influence of air mass origin on the wet deposition of nitrogen to Tampa Bay, Florida—An eight-year study

    NASA Astrophysics Data System (ADS)

    Strayer, Hillary; Smith, Ronald; Mizak, Connie; Poor, Noreen

    Rainfall delivers on the average ˜10% of the total annual nitrogen load directly to Tampa Bay, based on precipitation monitoring at a National Atmospheric Deposition Program (NADP) Atmospheric Integrated Research Monitoring Network (AIRMoN) site located adjacent to Tampa Bay in urban Tampa. We coupled the chemical analyses for 606 daily precipitation samples collected from 1996 to 2004 with corresponding air mass trajectory information to investigate if wet-deposited nitrogen originated from near versus removed source regions. Air mass trajectories were obtained using the National Oceanic and Atmospheric Administration (NOAA) HYbrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, and were classified into six trajectory categories by the direction of their approach to Tampa Bay. Rainfall nitrate and ammonium concentrations were significantly lower for over-water air mass trajectories than for over-land trajectories as expected, but contributed to 40% of the total wet-deposited nitrogen, a likely consequence of the higher frequency of rain events for these trajectories. Average rainfall nitrate concentrations were significantly higher for air masses that stagnated over the urbanized bay region. We estimated that local sources contributed 1kgNha-1yr-1 or 25% of the total inorganic nitrogen wet-deposited to Tampa Bay.

  7. Corner height influences center of mass kinematics and path trajectory during turning.

    PubMed

    Fino, Peter C; Lockhart, Thurmon E; Fino, Nora F

    2015-01-01

    Despite the prevalence of directional changes during every-day gait, relatively little is known about turning compared to straight gait. While the center of mass (COM) movement during straight gait is well characterized, the COM trajectory and the factors that influence it are less established for turning. This study investigated the influence of a corner׳s height on the COM trajectory as participants walked around the corner. Ten participants (25.3±3.74 years) performed both 90° step and spin turns to the left at self-selected slow, normal, and fast speeds while walking inside a marked path. A pylon was placed on the inside corner of the path. Four different pylon heights were used to correspond to heights of everyday objects: 0 cm (no object), 63 cm (box, crate), 104 cm (desk, table, counter), 167 cm (shelf, cabinet). Obstacle height was found to significantly affect the COM trajectory. Taller obstacles resulted in more distance between the corner and the COM, and between the corner and the COP. Taller obstacles also were associated with greater curvature in the COM trajectory, indicating a smaller turning radius despite the constant 90° corner. Taller obstacles correlated to an increased required coefficient of friction (RCOF) due to the smaller turning radii. Taller obstacles also tended towards greater mediolateral (ML) COM-COP angles, contrary to the initial hypothesis. Additionally, the COM was found to remain outside the base of support (BOS) for the entire first half of stance phase for all conditions indicating a high risk of falls resulting from slips.

  8. Body Mass Index Trajectories and Healthcare Utilization in Young and Middle-aged Adults

    PubMed Central

    Elrashidi, Muhamad Y.; Jacobson, Debra J.; St. Sauver, Jennifer; Fan, Chun; Lynch, Brian A.; Rutten, Lila J. Finney; Ebbert, Jon O.

    2016-01-01

    Abstract The obesity epidemic is a significant public health issue with adverse impact on health and costs. Applying a life-course perspective to obesity may advance our understanding of the influence of obesity over time on patterns of healthcare utilization in young and middle-aged United States (US) adults. We identified baseline body mass index (BMI) and BMI trajectories, and assessed their association with outpatient visits, emergency department (ED) visits, and hospitalizations in a well-defined population of young and middle-aged US adults. Using the Rochester Epidemiology Project resources, we conducted a retrospective cohort study of adults (N = 23,254) aged 18 to 44 years, with at least 3 BMI measurements, residing in Olmsted County, MN from January 1, 2005 through December 31, 2012. We observed that 27.5% of the population was obese. Four BMI trajectories were identified. Compared to under/normal weight, obese class III adults had higher risk of outpatient visits (adjusted rate ratio [RR], 1.86; 95% confidence intervals [CIs], 1.67–2,08), ED visits (adjusted RR, 3.02; 95% CI, 2.74–3.34), and hospitalizations (adjusted RR, 1.67; 95% CI, 1.59–1.75). BMI trajectory was positively associated with ED visits after adjustment for age, sex, race, and Charlson Comorbidity Index (P < 0.001 for trend). Among young and middle-aged US adults, baseline BMI is positively associated with outpatient visits, ED visits, and hospitalizations, while BMI trajectory is positively associated with ED visits. These findings extend our understanding of the longitudinal influence of obesity on healthcare utilization in early to mid-adulthood. PMID:26765446

  9. Establishing Lagrangian Connections between Observations within Air Masses Crossing the Atlantic during the ICARTT Experiment

    NASA Technical Reports Server (NTRS)

    Methven, J.; Arnold, S. R.; Stohl, A.; Evans, M. J.; Avery, M.; Law, K.; Lewis, A. C.; Monks, P. S.; Parrish, D.; Reeves, C.; Schlager, H.; Atlas, E.; Blake, D.; Coe, H.; Cohen, R. C.; Crosier, J.; Flocke, F.; Holloway, J. S.; Hopkins, J. R.; Huber, G.; McQuaid, J.; Purvis, R.; Rappengluck, B.; Ryerson, T. B.; Sachse, G. W.

    2006-01-01

    The International Consortium for Atmospheric Research on Transport and Transformation (ICARTT)-Lagrangian experiment was conceived with an aim to quantify the effects of photochemistry and mixing on the transformation of air masses in the free troposphere away from emissions. To this end attempts were made to intercept and sample air masses several times during their journey across the North Atlantic using four aircraft based in New Hampshire (USA), Faial (Azores) and Creil (France). This article begins by describing forecasts using two Lagrangian models that were used to direct the aircraft into target air masses. A novel technique is then used to identify Lagrangian matches between flight segments. Two independent searches are conducted: for Lagrangian model matches and for pairs of whole air samples with matching hydrocarbon fingerprints. The information is filtered further by searching for matching hydrocarbon samples that are linked by matching trajectories. The quality of these coincident matches is assessed using temperature, humidity and tracer observations. The technique pulls out five clear Lagrangian cases covering a variety of situations and these are examined in detail. The matching trajectories and hydrocarbon fingerprints are shown and the downwind minus upwind differences in tracers are discussed.

  10. Influence of Baseline Air Masses and Wildland Fires on Air Quality in the Western United States

    NASA Astrophysics Data System (ADS)

    Wigder, Nicole L.

    This dissertation focuses on several key uncertainties related to particulate matter (PM) and O3 concentrations in the western U.S. Each analysis conducted for this dissertation centers on data collected at the Mount Bachelor Observatory (MBO, 2.8 km a.s.l., 43.98° N, 121.69° W), a mountaintop research site in central Oregon, U.S. The first component of this dissertation is an analysis of the contribution of baseline O3 to observed O3 concentrations in two western U.S. urban areas, Enumclaw, Washington (WA) and Boise, Idaho, during 2004 -- 2010. I compared O3 data from two baseline sites (MBO and Cheeka Peak, WA) to O3 concentrations in the two urban areas on days when backward air mass trajectories showed transport between the baseline and urban sites. I found that the urban areas studied had relatively low O3 on the days with a strong influence from baseline air masses (28.3 -- 48.3 ppbv). These data suggested that there was low production of O3 from urban emissions on these days, which allowed me to quantify the impact of baseline O3 on urban O3 concentrations. A regression of the Boise and MBO O3 observations showed that free tropospheric air masses were diluted by 50% as they were entrained into the boundary layer at Boise. These air masses can contain high O3 concentrations (>70 ppbv) from Asian pollution sources or stratospheric intrusions, indicating that these sources can greatly contribute to urban surface O 3 concentrations. In addition, I found that the elevation and surface temperature of the urban areas studied impacted baseline O3 concentrations in these areas, with higher elevation and greater surface temperatures leading to greater O3 concentrations. The second and third components of this dissertation are analyses of the impact of wildland fires on PM and O3 concentrations in the western U.S. For both of these analyses, I calculated pollutant enhancement ratios for PM, O3, and other species in wildland fire plumes observed at MBO during 2004

  11. Complexity analysis of the Next Gen Air Traffic Management System: trajectory based operations.

    PubMed

    Lyons, Rhonda

    2012-01-01

    According to Federal Aviation Administration traffic predictions currently our Air Traffic Management (ATM) system is operating at 150 percent capacity; forecasting that within the next two decades, the traffic with increase to a staggering 250 percent [17]. This will require a major redesign of our system. Today's ATM system is complex. It is designed to safely, economically, and efficiently provide air traffic services through the cost-effective provision of facilities and seamless services in collaboration with multiple agents however, contrary the vision, the system is loosely integrated and is suffering tremendously from antiquated equipment and saturated airways. The new Next Generation (Next Gen) ATM system is designed to transform the current system into an agile, robust and responsive set of operations that are designed to safely manage the growing needs of the projected increasingly complex, diverse set of air transportation system users and massive projected worldwide traffic rates. This new revolutionary technology-centric system is dynamically complex and is much more sophisticated than it's soon to be predecessor. ATM system failures could yield large scale catastrophic consequences as it is a safety critical system. This work will attempt to describe complexity and the complex nature of the NextGen ATM system and Trajectory Based Operational. Complex human factors interactions within Next Gen will be analyzed using a proposed dual experimental approach designed to identify hazards, gaps and elicit emergent hazards that would not be visible if conducted in isolation. Suggestions will be made along with a proposal for future human factors research in the TBO safety critical Next Gen environment.

  12. Measurements of CO in an aircraft experiment and their correlation with biomass burning and air mass origin in South America

    NASA Astrophysics Data System (ADS)

    Boian, C.; Kirchhoff, V. W. J. H.

    Carbon monoxide (CO) measurements are obtained in an aircraft experiment during 1-7 September 2000, conducted over Central Brazil in a special region of anticyclonic circulation. This is a typical transport regime during the dry season (July-September), when intense biomass burning occurs, and which gives origin to the transport of burning poluents from the source to distant regions. This aircraft experiment included in situ measurements of CO concentrations in three different scenarios: (1) areas of fresh biomass burning air masses, or source areas; (2) areas of aged biomass burning air masses; and (3) areas of clean air or pristine air masses. The largest CO concentrations were of the order of 450 ppbv in the source region near Conceicao do Araguaia (PA), and the smallest value near 100 ppbv, was found in pristine air masses, for example, near the northeast coastline (clean air, or background region). The observed concentrations were compared to the number of fire pixels seen by the AVHRR satellite instrument. Backward isentropic trajectories were used to determine the origin of the air masses at each sampling point. From the association of the observed CO mixing ratios, fire pixels and air mass trajectories, the previous scenarios may be subdivided as follows: (1a) source regions of biomass burning with large CO concentrations; (1b) regions with few local fire pixels and absence of contributions by transport. Areas with these characteristics include the northeast region of Brazil; (1c) regions close to the source region and strongly affected by transport (region of Para and Amazonas); (2) regions that have a consistent convergence of air masses, that have traveled over biomass burning areas during a few days (western part of the Cerrado region); (3a) Pristine air masses with origin from the ocean; (3b) regions with convergent transport that has passed over areas of no biomass burning, such as frontal weather systems in the southern regions.

  13. Air-breathing hypersonic vehicle guidance and control studies; An integrated trajectory/control analysis methodology: Phase 1

    NASA Technical Reports Server (NTRS)

    Hattis, Philip D.; Malchow, Harvey L.

    1991-01-01

    A tool which generates optimal trajectory/control histories in an integrated manner is generically adapted to the treatment of single-stage-to-orbit air-breathing hypersonic vehicles. The methodology is implemented as a two point boundary value problem solution technique. Its use permits an assessment of an entire near-minimum-fuel trajectory and desired control strategy from takeoff to orbit while satisfying physically derived inequality constraints and while achieving efficient propulsive mode phasing. A simpler analysis strategy that partitions the trajectory into several boundary condition matched segments is also included to construct preliminary trajectory and control history representations with less computational burden than is required for the overall flight profile assessment. A demonstration was accomplished using a tabulated example (winged-cone accelerator) vehicle model that is combined with a newly developed multidimensional cubic spline data smoothing routine. A constrained near-fuel-optimal trajectory, imposing a dynamic pressure limit of 1000 psf, was developed from horizontal takeoff to 20,000 ft/sec relative air speed while aiming for a polar orbit. Previously unspecified propulsive discontinuities were located. Flight regimes demanding rapid attitude changes were identified, dictating control effector and closed-loop controller authority was ascertained after evaluating effector use for vehicle trim. Also, inadequacies in vehicle model representations and specific subsystem models with insufficient fidelity were determined based on unusual control characteristics and/or excessive sensitivity to uncertainty.

  14. Mass change of Northwest Spitsbergen glaciers for a range of 21st century climate trajectories

    NASA Astrophysics Data System (ADS)

    Willis, Ian; Cogbill, Rhiannon; Rye, Cameron; Arnold, Neil

    2016-04-01

    The maritime setting of northwest Spitsbergen, Svalbard make its glaciers highly sensitive to enhanced global warming. Modelling the effects of this warming on glacier mass balance in the region is therefore important for quantifying their future contribution to sea level. Here, we develop a mass balance model using the positive degree approach, and calibrate it against data for two benchmark glaciers, Midre Lovénbreen and Kongsvegen. The model is used, together with volume-area scaling, to calculate the future mass balance of all glaciers across northwest Spitsbergen throughout the 21st century. Future socio-economic climatic trajectories were chosen from statistically downscaled outputs for RCP2.6, 4.5 and 8.5 of several CMIP5 GCMs to incorporate a complete envelope of possible futures. The regional volume loss was projected, on average, to be 31.3 ± 17.3% of the 2006 volume, contributing 1.11 ±0.61 mm to SLR by 2100. The future mass balance is primarily dominated by temperature, particularly for the high-emission scenarios where temperature explains 87% of the variation in mass balance for 2006-2100. There are considerable spatial variations in the response of glaciated northwest Spitsbergen to climate, driven by local glaciological characteristics. This is evident from the significantly greater sensitivity of the small, low altitude Midre Lovénbreen to climatic change compared to the larger Kongsvegen, which extends to higher elevations. Our model predicts an envelope of future mass loss and sea level contribution that is somewhat lower than similar previous studies.

  15. Uncertainty analysis and robust trajectory linearization control of a flexible air-breathing hypersonic vehicle

    NASA Astrophysics Data System (ADS)

    Pu, Zhiqiang; Tan, Xiangmin; Fan, Guoliang; Yi, Jianqiang

    2014-08-01

    Flexible air-breathing hypersonic vehicles feature significant uncertainties which pose huge challenges to robust controller designs. In this paper, four major categories of uncertainties are analyzed, that is, uncertainties associated with flexible effects, aerodynamic parameter variations, external environmental disturbances, and control-oriented modeling errors. A uniform nonlinear uncertainty model is explored for the first three uncertainties which lumps all uncertainties together and consequently is beneficial for controller synthesis. The fourth uncertainty is additionally considered in stability analysis. Based on these analyses, the starting point of the control design is to decompose the vehicle dynamics into five functional subsystems. Then a robust trajectory linearization control (TLC) scheme consisting of five robust subsystem controllers is proposed. In each subsystem controller, TLC is combined with the extended state observer (ESO) technique for uncertainty compensation. The stability of the overall closed-loop system with the four aforementioned uncertainties and additional singular perturbations is analyzed. Particularly, the stability of nonlinear ESO is also discussed from a Liénard system perspective. At last, simulations demonstrate the great control performance and the uncertainty rejection ability of the robust scheme.

  16. An investigation of particle trajectories and melting in an air plasma sprayed zirconia

    SciTech Connect

    Neiser, R.A.; Roemer, T.J.

    1996-12-31

    The partially stabilized zirconia powders used to plasma spray thermal barrier coatings typically exhibit broad particle-size distributions. There are conflicting reports in the literature about the extent of injection-induced particle-sizing effects in air plasma-sprayed materials. If significant spatial separation of finer and coarser particles in the jet occurs, then one would expect it to play an important role in determining the microstructure and properties of deposits made from powders containing a wide range of particle sizes. This paper presents the results of a study in which a commercially available zirconia powder was fractionated into fine, medium, and coarse cuts and sprayed at the same torch conditions used for the ensemble powder. Diagnostic measurements of particle surface temperature, velocity, and number-density distributions in the plume for each size-cut and for the ensemble powder are reported. Deposits produced by traversing the torch back and forth to produce a raised bead were examined metallographically to study their shape and location with respect to the torch centerline and to look at their internal microstructure. The results show that, for the torch conditions used in this study, the fine, medium, and coarse size-cuts all followed the same mean trajectory. No measureable particle segregation effects were observed. Considerable differences in coatings microstructure were observed. These differences can be explained by the different particle properties measured in the plume.

  17. Cosmic dust investigations II. Instruments for measurement of particle trajectory, velocity and mass

    NASA Astrophysics Data System (ADS)

    Simpson, J. A.; Tuzzolino, A. J.

    1989-07-01

    A series of experiments have been completed using accelerator dust particles in the mass range ~10-9-10-6 g and velocity range ~2-12 km/s to measure the velocity loss and degree of fragmentation for dust particles penetrating 6 and 28 μm thick polyvinylidene fluoride (PVDF) dust detectors. These measurements prove that even for a ratio of PVDF foil thickness to particle diameter as large as 0.6, the velocity loss and fragmentation is far less than expected from earlier reports in the literature. For example, for 28 μm thick PVDF foils the velocity loss is ~ 20%, the fraction of particles suffering serious fragmentation is ~ 50% and the angular dispersion or ``spray angle'' of the fragments from the incident particle direction is <= 3°. For 6 μm thick foils the velocity loss is <= 5%. These experiments are based on an extension of our earlier work which showed that two PVDF foils spaced a given distance apart could provide accurate time-of-flight (TOF) information due to the fast pulse rise time of PVDF detector response. We also report on our present state of development of PVDF position-sensing detectors which identify the x, y coordinates of particle impact, using detector and electronic pulse techniques adapted from our semiconductor position-sensing cosmic-ray detectors. Typical position errors of ~ 1 mm are readily achieved. Finally, we have combined the above developments into a dust-particle telescope which accurately (~ 1° angular accuracy) measures the trajectory of the incident particle as well as its mass and incident velocity, irrespective of whether it is a charged or neutral particle. We discuss how this practical dust telescope can be combined with dust capture cells for space flight and later recovery for laboratory determination of elemental and isotopic composition of captured dust. We also describe a simpler trajectory array based on discrete mosaics of thin detectors which would measure trajectories with a mean angular error of ~ 4°. We

  18. How to Compute Green's Functions for Entire Mass Trajectories Within Krylov Solvers

    NASA Astrophysics Data System (ADS)

    Glässner, Uwe; Güsken, Stephan; Lippert, Thomas; Ritzenhöfer, Gero; Schilling, Klaus; Frommer, Andreas

    The availability of efficient Krylov subspace solvers plays a vital role in the solution of a variety of numerical problems in computational science. Here we consider lattice field theory. We present a new general numerical method to compute many Green's functions for complex non-singular matrices within one iteration process. Our procedure applies to matrices of structure A = D - m, with m proportional to the unit matrix, and can be integrated within any Krylov subspace solver. We can compute the derivatives x(n) of the solution vector x with respect to the parameter m and construct the Taylor expansion of x around m. We demonstrate the advantages of our method using a minimal residual solver. Here the procedure requires one intermediate vector for each Green's function to compute. As real-life example, we determine a mass trajectory of the Wilson fermion matrix for lattice QCD. Here we find that we can obtain Green's functions at all masses ≥ m at the price of one inversion at mass m.

  19. The effects of air mass transport, seasonality, and meteorology on pollutant levels at the Iskrba regional background station (1996-2014)

    NASA Astrophysics Data System (ADS)

    Poberžnik, Matevž; Štrumbelj, Erik

    2016-06-01

    Our main goal was to estimate the effects of long-range air transport on pollutant concentrations measured at the Iskrba regional background station (Slovenia). We cluster back-trajectories into categories and simultaneously model the effects of meteorology, seasonality, trends, and air mass trajectory clusters using a Bayesian statistical approach. This simplifies the interpretation of results and allows us to better identify the effects of individual variables, which is important, because pollutant concentrations, meteorology, and trajectories are seasonal and correlated. Similar to related work from other European sites, we find that slow and faster moving trajectories from eastern Europe and the northern part of the Balkan peninsula are associated with higher pollutant levels, while fast-moving trajectories from the Atlantic are associated with lower pollutant concentration. Overall, pollutant concentrations have decreased in the studied period.

  20. Interaction of mid-latitude air masses with the polar dome area during RACEPAC and NETCARE

    NASA Astrophysics Data System (ADS)

    Bozem, Heiko; Hoor, Peter; Koellner, Franziska; Kunkel, Daniel; Schneider, Johannes; Schulz, Christiane; Herber, Andreas; Borrmann, Stephan; Wendisch, Manfred; Ehrlich, Andre; Leaitch, Richard; Willis, Megan; Burkart, Julia; Thomas, Jennie; Abbatt, Jon

    2016-04-01

    We present aircraft based trace gas measurements in the Arctic during RACEPAC (2014) and NETCARE (2014 and 2015) with the Polar 6 aircraft of Alfred Wegener Institute (AWI) covering an area from 134°W to 17°W and 68°N to 83°N. We focus on cloud, aerosol and general transport processes of polluted air masses into the high Arctic. Based on CO and CO2 measurements and kinematic 10-day back trajectories as well as Flexpart particle dispersion modeling we analyze the transport regimes of mid-latitude air masses traveling to the high Arctic prevalent during spring (RACEPAC 2014, NETCARE 2015) and summer (NETCARE 2014). In general more northern parts of the high Arctic (Lat > 75°N) were relatively unaffected from mid-latitude air masses. In contrast, regions further south are influenced by air masses from Asia and Russia (eastern part of Canadian Arctic and European Arctic) as well as from North America (central and western parts of Canadian Arctic). The transition between the mostly isolated high Arctic and more southern regions indicated by tracer gradients is remarkably sharp. This allows for a chemical definition of the Polar dome based on the variability of CO and CO2 as a marker. Isentropic surfaces that slope from the surface to higher altitudes in the high Arctic form the polar dome that represents a transport barrier for mid-latitude air masses to enter the lower troposphere in the high Arctic. Synoptic-scale weather systems frequently disturb this transport barrier and foster the exchange between air masses from the mid-latitudes and polar regions. This can finally lead to enhanced pollution levels in the lower polar troposphere. Mid-latitude pollution plumes from biomass burning or flaring entering the polar dome area lead to an enhancement of 30% of the observed CO mixing ratio within the polar dome area.

  1. Impacts of Typhoon and Air-Mass Pathways on Rainwater Chemical Compositions

    NASA Astrophysics Data System (ADS)

    Cheng, M.; You, C.

    2006-12-01

    To assess the importance of chemical fluxes on trace elements by wet precipitation, we have collected time- series rain waters between 06/20/04 and 09/20/05 for ICPMS and IC measurements. The sampling site is located at Tainan city in southwest Taiwan and there were four typhoons, namely Mindulle, Rananim, Aere, and Haima, hit the island during this period. Combining trace element compositions with HYSPLIT model for air-mass transportation designed by NOAA, we were able to understand possible source, flux and migration pathway of pollutants in rainwater. Our results show that seasalt contribution and trace element fluxes were higher during typhoon events. The Na and Pb flux varied largely, between 0.03~1388 and 0.0002~2000 mg/m2/day respectively, depended on the pathways of air mass trajectory and wind strength. It is clear that typhoons carry not only sea spray but also major anthropogenic pollutants from south Asia. Among the four typhoons, the Mindulle carried the largest fluxes of seasalt and trace elements while Rananim was weak in strength and brought the lowest Na and Pb due to less degree of mixing with air mass on land. The calculated enriched factors normalized to seawater (EFsea) were near unity for Na and Mg, but were much larger for K and Ca possibly due to crust source contamination and biomass burning. The EFcrust or EFsea values of various trace metals (e.g., V, Cr, Mn, Co, Ni, Cu, Zn, As, Ba and Pb were all significantly larger than 10 indicating the importance of anthropogenic sources. Interestingly, the PCA results confirm that rain waters with similar chemical characteristics have shared common air mass backward trajectory history.

  2. Air-breathing hypersonic vehicle guidance and control studies: An integrated trajectory/control analysis methodology, phase 2

    NASA Technical Reports Server (NTRS)

    Hattis, Philip D.; Malchow, Harvey L.

    1992-01-01

    An integrated trajectory/control analysis algorithm has been used to generate trajectories and desired control strategies for two different hypersonic air-breathing vehicle models and orbit targets. Both models used cubic spline curve fit tabulated winged-cone accelerator vehicle representations. Near-fuel-optimal, horizontal takeoff trajectories, imposing a dynamic pressure limit of 1000 psf, were developed. The first model analysis case involved a polar orbit and included the dynamic effects of using elevons to maintain longitudinal trim. Analysis results indicated problems with the adequacy of the propulsion model and highlighted dynamic pressure/altitude instabilities when using vehicle angle of attack as a control variable. Also, the magnitude of computed elevon deflections to maintain trim suggested a need for alternative pitch moment management strategies. The second analysis case was reformulated to use vehicle pitch attitude relative to the local vertical as the control variable. A new, more realistic, air-breathing propulsion model was incorporated. Pitch trim calculations were dropped and an equatorial orbit was specified. Changes in flight characteristics due to the new propulsion model have been identified. Flight regimes demanding rapid attitude changes have been noted. Also, some issues that would affect design of closed-loop controllers were ascertained.

  3. Air sparging effectiveness: laboratory characterization of air-channel mass transfer zone for VOC volatilization.

    PubMed

    Braida, W J; Ong, S K

    2001-10-12

    Air sparging in conjunction with soil vapor extraction is one of many technologies currently being applied for the remediation of groundwater contaminated with volatile organic compounds (VOCs). Mass transfer at the air-water interface during air sparging is affected by various soil and VOC properties. In this study with a single air-channel apparatus, mass transfer of VOCs was shown to occur within a thin layer of saturated porous media next to the air channel. In this zone, the VOCs were found to rapidly deplete during air sparging resulting in a steep concentration gradient while the VOC concentration outside the zone remained fairly constant. The sizes of the mass transfer zone were found to range from 17 to 41 mm or 70d(50) and 215d(50) (d(50)=mean particle size) for low organic carbon content media (<0.01% OC). The size of the mass transfer zone was found to be proportional to the square root of the aqueous diffusivity of the VOC, and was affected by the mean particle size, and the uniformity coefficient. Effects of the volatility of the VOCs as represented by the Henry's law constants and the airflow rates on the mass transfer zone were found to be negligible but VOC mass transfer from air-water interface to bulk air phase seems to play a role. A general correlation for predicting the size of the mass transfer zone was developed. The model was developed using data from nine different VOCs and verified by two other VOCs. The existence of the mass transfer zone provides an explanation for the tailing effect of the air phase concentration under prolonged air sparging and the rebound in the VOC air phase concentration after the sparging system is turned off.

  4. Variation in particulate PAHs levels and their relation with the transboundary movement of the air masses.

    PubMed

    Ravindra, Khaiwal; Wauters, Eric; Van Grieken, René

    2008-06-25

    The levels of particulate polycyclic aromatic hydrocarbons (PAHs) were determined with a fast analytical approach to study their seasonal variations at Menen (Belgium) during 2003; they were found to be 5-7 times higher in January, February and December, in comparison to May, June and August. The annual average concentration of the sum of 16 US Environmental Protection Agency (EPA) criteria PAHs was 6.7 ng/m3 and around 63% of it was found to be probably carcinogenic to humans. The application of diagnostic ratio and principal component analysis showed vehicular emission as a major source. An increased ratio of 'combustion PAHs' to 'total EPA-PAHs' during the winter season indicated towards combustion activities. Further, the differences in PAHs concentration were assessed with relation to backward air mass trajectories, which show that the levels of PAHs increase when there is an air mass movement from Central and Western Europe and a fall when the trajectories spend most of their 4-day time over the Atlantic Ocean or in the Arctic region.

  5. The Use of Red Green Blue Air Mass Imagery to Investigate the Role of Stratospheric Air in a Non-Convective Wind Event

    NASA Technical Reports Server (NTRS)

    Berndt, E. B.; Zavodsky, B. T.; Moltham, A. L.; Folmer, M. J.; Jedlovec, G. J.

    2014-01-01

    The investigation of non-convective winds associated with passing extratropical cyclones and the formation of the sting jet in North Atlantic cyclones that impact Europe has been gaining interest. Sting jet research has been limited to North Atlantic cyclones that impact Europe because it is known to occur in Shapiro-Keyser cyclones and theory suggests it does not occur in Norwegian type cyclones. The global distribution of sting jet cyclones is unknown and questions remain as to whether cyclones with Shapiro-Keyser characteristics that impact the United States develop features similar to the sting jet. Therefore unique National Aeronautics and Space Administration (NASA) products were used to analyze an event that impacted the Northeast United States on 09 February 2013. Moderate Resolution Imaging Spectroradiometer (MODIS) Red Green Blue (RGB) Air Mass imagery and Atmospheric Infrared Sounder (AIRS) ozone data were used in conjunction with NASA's global Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis and higher-resolution regional 13-km Rapid Refresh (RAP) data to analyze the role of stratospheric air in producing high winds. The RGB Air Mass imagery and a new AIRS ozone anomaly product were used to confirm the presence of stratospheric air. Plan view and cross sectional plots of wind, potential vorticity, relative humidity, omega, and frontogenesis were used to analyze the relationship between stratospheric air and high surface winds during the event. Additionally, the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model was used to plot trajectories to determine the role of the conveyor belts in producing the high winds. Analyses of new satellite products, such as the RGB Air Mass imagery, show the utility of future GOES-R products in forecasting non-convective wind events.

  6. Evaluation of some significant issues affecting trajectory and control management for air-breathing hypersonic vehicles

    NASA Astrophysics Data System (ADS)

    Hattis, Philip D.; Malchow, Harvey L.

    1992-12-01

    Horizontal takeoff airbreathing-propulsion launch vehicles require near-optimal guidance and control which takes into account performance sensitivities to atmospheric characteristics while satisfying physically-derived operational constraints. A generic trajectory/control analysis tool that deepens insight into these considerations has been applied to two versions of a winged-cone vehicle model. Information that is critical to the design and trajectory of these vehicles is derived, and several unusual characteristics of the airbreathing propulsion model are shown to have potentially substantial effects on vehicle dynamics.

  7. Evaluation of some significant issues affecting trajectory and control management for air-breathing hypersonic vehicles

    NASA Technical Reports Server (NTRS)

    Hattis, Philip D.; Malchow, Harvey L.

    1992-01-01

    Horizontal takeoff airbreathing-propulsion launch vehicles require near-optimal guidance and control which takes into account performance sensitivities to atmospheric characteristics while satisfying physically-derived operational constraints. A generic trajectory/control analysis tool that deepens insight into these considerations has been applied to two versions of a winged-cone vehicle model. Information that is critical to the design and trajectory of these vehicles is derived, and several unusual characteristics of the airbreathing propulsion model are shown to have potentially substantial effects on vehicle dynamics.

  8. Number size distribution of aerosols at Mt. Huang and Nanjing in the Yangtze River Delta, China: Effects of air masses and characteristics of new particle formation

    NASA Astrophysics Data System (ADS)

    Wang, Honglei; Zhu, Bin; Shen, Lijuan; An, Junlin; Yin, Yan; Kang, Hanqing

    2014-12-01

    Aerosol number spectra in the range of 10 nm-10 μm were observed at Mt. Huang (Aug. 15-Sep. 15) and Nanjing (Oct. 13-Nov. 15) by a wide-range particle spectrometer (WPS) in 2011. Based on the backward trajectories obtained using the HYSPLIT model, the transport pathways of observed air masses during the study periods were classified into the following four groups: maritime air mass, continental air mass, marine-continental mixed air mass and local air mass. The variations in the aerosol number spectrum and the new particle formation (NPF) events for various types of air masses were discussed, along with meteorological data. The results showed that the average number concentration was 12,540 cm- 3 at Nanjing and only 2791 cm- 3 at Mt. Huang. The aerosol number concentration in Nanjing was 3-7 times higher than that in Mt. Huang; the large discrepancy was in the range of 10-100 nm. Different types of air masses had different effects on number concentration distribution. The number concentration of aerosols was higher in marine air masses, continental air masses and continental-marine mixed air masses at 10-50 nm, 100-500 nm and 50-200 nm, respectively. Under the four types of air masses, the aerosol size spectra had bimodal distributions in Nanjing and unimodal distributions in Mt. Huang (except under continental air masses: HT1). The effects of the diverse air masses on aerosol size segments of the concentration peak in Mt. Huang were stronger than those in Nanjing. The local air masses were dominant at these two sites and accounted for 44% of the total air masses. However, the aerosol number concentration was the lowest in Mt. Huang and the highest in Nanjing when local air masses were present. The number concentrations for foreign air masses increased at Mt. Huang and decreased at Nanjing. Different types of air masses had greater effects on the aerosol spectrum distribution at Mt. Huang than at Nanjing. During the NPF events, the particle growth rates at Mt

  9. Automated Cooperative Trajectories for a More Efficient and Responsive Air Transportation System

    NASA Technical Reports Server (NTRS)

    Hanson, Curt

    2015-01-01

    The NASA Automated Cooperative Trajectories project is developing a prototype avionics system that enables multi-vehicle cooperative control by integrating 1090 MHz ES ADS-B digital communications with onboard autopilot systems. This cooperative control capability will enable meta-aircraft operations for enhanced airspace utilization, as well as improved vehicle efficiency through wake surfing. This briefing describes the objectives and approach to a flight evaluation of this system planned for 2016.

  10. Noncontact ultrasonic transportation of small objects in a circular trajectory in air by flexural vibrations of a circular disc.

    PubMed

    Koyama, Daisuke; Nakamura, Kentaro

    2010-06-01

    We have developed a noncontact ultrasonic technique for transporting small objects with a linear trajectory over long distances using a bending vibrating plate and a reflector. In this paper, noncontact transportation of small particles around a circular trajectory was investigated. A circular aluminum plate with a piezoelectric ring was employed as a vibrating plate. On the basis of finite element analysis (FEA) calculations, the electrodes of the piezoelectric ring were divided into 24 pieces to generate a flexural vibration mode with one nodal circle and four nodal lines at the resonance frequency of 47.8 kHz. A circular plate having the same dimensions as the vibrating plate was installed parallel to the vibrator. It was used as a reflector to generate an acoustic standing wave in the air between the two plates. The acoustic field between the vibrating plate and reflector was calculated by FEA and the distribution of the acoustic radiation force acting on a small rigid particle was calculated to predict the position of the trapped particle. Using a prototype of the vibrating plate, polystyrene particles with diameters of several millimeters could be trapped at regular intervals along the horizontal nodal line of the standing wave. The sound pressure distribution between the vibrating plate and reflector was measured by a fiber optic probe and the experimental and calculated results showed good agreement. By switching the driving conditions of the divided electrodes in the circumferential direction, the nodal lines of the vibrating plate could be rotated and the trapped particle could be manipulated with a circular trajectory in air. PMID:20529718

  11. Warm-air advection, air mass transformation and fog causes rapid ice melt

    NASA Astrophysics Data System (ADS)

    Tjernström, Michael; Shupe, Matthew D.; Brooks, Ian M.; Persson, P. Ola G.; Prytherch, John; Salisbury, Dominic J.; Sedlar, Joseph; Achtert, Peggy; Brooks, Barbara J.; Johnston, Paul E.; Sotiropoulou, Georgia; Wolfe, Dan

    2015-07-01

    Direct observations during intense warm-air advection over the East Siberian Sea reveal a period of rapid sea-ice melt. A semistationary, high-pressure system north of the Bering Strait forced northward advection of warm, moist air from the continent. Air-mass transformation over melting sea ice formed a strong, surface-based temperature inversion in which dense fog formed. This induced a positive net longwave radiation at the surface while reducing net solar radiation only marginally; the inversion also resulted in downward turbulent heat flux. The sum of these processes enhanced the surface energy flux by an average of ~15 W m-2 for a week. Satellite images before and after the episode show sea-ice concentrations decreasing from > 90% to ~50% over a large area affected by the air-mass transformation. We argue that this rapid melt was triggered by the increased heat flux from the atmosphere due to the warm-air advection.

  12. A Novel Method to Describe Early Offspring Body Mass Index (BMI) Trajectories and to Study Its Determinants

    PubMed Central

    Carles, Sophie; Charles, Marie-Aline; Forhan, Anne; Slama, Rémy; Heude, Barbara; Botton, Jérémie

    2016-01-01

    Background Accurately characterizing children’s body mass index (BMI) trajectories and studying their determinants is a statistical challenge. There is a need to identify early public health measures for obesity prevention. We describe a method that allows studies of the determinants of height, weight and BMI growth up to five years of age. We illustrated this method using maternal smoking during pregnancy as one of the early-life factors that is potentially involved in prenatal programming of obesity. Methods Individual height and weight trajectories were fitted using the Jenss-Bayley model on 28,381 and 30,515 measurements, respectively, from 1,666 children to deduce BMI trajectories. We assessed global associations between smoking and growth trajectories and cross-sectional associations at specific ages. Results Children exposed in late pregnancy had a 0.24 kg/m2 (95% confidence interval: 0.07, 0.41) higher BMI at 5 years of age compared with non-exposed children. Although the BMIs of children exposed during late pregnancy became significantly higher compared with those of non-exposed children from 2 years onwards, the trajectories began to diverge during the first weeks of life. Conclusion Our method is relevant for studies on the relationships between individual-level exposures and the dynamics and shapes of BMI growth during childhood, including key features such as instantaneous growth velocities and the age or BMI value at the BMI infancy peak that benefit from the monotonic pattern of height and weight growth. PMID:27327164

  13. Characteristics of dimethylsulfide, ozone, aerosols, and cloud condensation nuclei in air masses over the northwestern Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nagao, Ippei; Matsumoto, Kiyoshi; Tanaka, Hiroshi

    1999-05-01

    Long-term measurements of several trace gases and aerosols were carried out from December 1994 to October 1996 at Ogasawara Hahajima Island over the northwestern Pacific Ocean. The continental impact on the concentrations of sulfur compounds, ozone (O3), and cloud condensation nuclei (CCN) was estimated on the basis of the classification of air mass into seven types by isentropic trajectory analysis. From May to October, the air mass originating from the central North Pacific Ocean is predominant and regarded as the clean marine air for the concentrations of sulfur compounds and CCN. From the results of the molar ratio of methane sulfonic acid to non-sea-salt sulfate (NSS) and the positive correlation between dimethylsulfide (DMS) and CCN in this air mass it can be concluded that DMS largely contributes to the production of NSS and CCN. On the other hand, continental and anthropogenic substances are preferably transported to the northwestern Pacific Ocean by the predominant continental air mass from November to March. The enhancement of concentrations by the outflow from the Asian continent are estimated by a factor of 2.8 for O3, 3.9 for SO2, 3.5 for CCN activated at 0.5% supersaturation (0.5% CCN), 4.7 for 1.0% CCN, and 5.5 for NSS. Moreover, the CCN supersaturation spectra are also affected by the continental substances resulting in factor 2 of enhancement of cloud droplet number concentration. The diurnal variations of DMS and O3 for each air mass show a pattern of daytime minimum and nighttime maximum, which are typically found in remote ocean, even though those amplitudes are different for each air mass. Consequently, it can be concluded that the influence of nitric oxides (NOx) for the daytime O3 production and nitrate (NO3) radical for the nighttime oxidation of DMS are small even in the continental air mass.

  14. Analysis of mass transfer performance in an air stripping tower

    SciTech Connect

    Chung, T.W.; Lai, C.H.; Wu, H.

    1999-10-01

    The carryover of working solution in a traditional stripping tower is of serious concern in real applications. A U-shaped spray tower to prevent carryover has been designed to study the stripping of water vapor from aqueous desiccant solutions of 91.8 to 95.8 wt% triethylene glycol. In this study, water vapor was removed from the diluted desiccant solution by heating the solution and stripping it with the ambient air. Therefore, the solution was concentrated to a desired concentration. This spray tower was capable of handling air flow rates from 3.2 to 5.13 kg/min and liquid flow rates from 1.6 to 2.76 kg/min. Since the literature data on air stripping towers are limited, studies on the mass transfer coefficient and other mass transfer parameters were carried out in this study. Under the operating conditions, the overall mass transfer coefficient calculated from the experimental data varied from 0.053 to 0.169 mol/m{sup 3}{center{underscore}dot}s. These corresponded to heights of a transfer unit of 2.3 to 0.71 m, respectively. The rates of stripping in this spray tower were typically varied from 2.28 to 12.15 kg H{sub 2}O/h. A correlation of the mass transfer coefficient for the air stripping process was also developed in this study.

  15. Following the Ions through a Mass Spectrometer with Atmospheric Pressure Interface: Simulation of Complete Ion Trajectories from Ion Source to Mass Analyzer.

    PubMed

    Zhou, Xiaoyu; Ouyang, Zheng

    2016-07-19

    Ion trajectory simulation is an important and useful tool in instrumentation development for mass spectrometry. Accurate simulation of the ion motion through the mass spectrometer with atmospheric pressure ionization source has been extremely challenging, due to the complexity in gas hydrodynamic flow field across a wide pressure range as well as the computational burden. In this study, we developed a method of generating the gas flow field for an entire mass spectrometer with an atmospheric pressure interface. In combination with the electric force, for the first time simulation of ion trajectories from an atmospheric pressure ion source to a mass analyzer in vacuum has been enabled. A stage-by-stage ion repopulation method has also been implemented for the simulation, which helped to avoid an intolerable computational burden for simulations at high pressure regions while it allowed statistically meaningful results obtained for the mass analyzer. It has been demonstrated to be suitable to identify a joint point for combining the high and low pressure fields solved individually. Experimental characterization has also been done to validate the new method for simulation. Good agreement was obtained between simulated and experimental results for ion transfer though an atmospheric pressure interface with a curtain gas.

  16. Following the Ions through a Mass Spectrometer with Atmospheric Pressure Interface: Simulation of Complete Ion Trajectories from Ion Source to Mass Analyzer.

    PubMed

    Zhou, Xiaoyu; Ouyang, Zheng

    2016-07-19

    Ion trajectory simulation is an important and useful tool in instrumentation development for mass spectrometry. Accurate simulation of the ion motion through the mass spectrometer with atmospheric pressure ionization source has been extremely challenging, due to the complexity in gas hydrodynamic flow field across a wide pressure range as well as the computational burden. In this study, we developed a method of generating the gas flow field for an entire mass spectrometer with an atmospheric pressure interface. In combination with the electric force, for the first time simulation of ion trajectories from an atmospheric pressure ion source to a mass analyzer in vacuum has been enabled. A stage-by-stage ion repopulation method has also been implemented for the simulation, which helped to avoid an intolerable computational burden for simulations at high pressure regions while it allowed statistically meaningful results obtained for the mass analyzer. It has been demonstrated to be suitable to identify a joint point for combining the high and low pressure fields solved individually. Experimental characterization has also been done to validate the new method for simulation. Good agreement was obtained between simulated and experimental results for ion transfer though an atmospheric pressure interface with a curtain gas. PMID:27340893

  17. The Use of Compensated Aerological No-Lift Balloons to Determine Relatively Long-Term Dry-Air Parcel Trajectories.

    NASA Astrophysics Data System (ADS)

    Terliuc, Benjamin; Asculai, Ephraim; Doron, Eli

    1983-10-01

    A method to compensate the loss of buoyancy due to gas leakage from aerological no-lift balloons is presented. The method is implemented by means of a double vessel device that supplies a constant liquid outflow at constant temperature. It is shown that the average buoyancy loss rate dependence on temperature is almost perfectly matched by the outflow rate dependence on temperature when soya-bean oil is used. The device is simple, inexpensive and can be easily manufactured using standard laboratory equipment.A simple and safe method to carry no-lift systems to prefixed levels is also presented. It is based on a single 30 g pilot balloon provided with a gas leakage nozzle, inflated with H2 to a calibrated initial free-lift. The balloon is totally emptied at the required level, and remains suspended from the no-lift system.The whole system can be easily prepared under field conditions to be used in long travel-time studies of dry-air parcel trajectories in the atmosphere.An example of the use of the improved method over complex terrain is presented. A no-lift system provided with a 1680 MHz radiosonde transmitter, was tracked by two RD-65 radio-theodolites, to investigate the effects of the topographic structure of the Lake Kinneret (Sea of Galilee) area on the Mediterranean sea breeze summer regime. The system was tracked for at least one hour, following a trajectory with severe vertical variations. This increases our confidence in the ability to track much longer trajectories, if required.

  18. Body Mass Index Trajectories among Middle-Aged and Elderly Canadians and Associated Health Outcomes

    PubMed Central

    Wang, Meng; Yi, Yanqing; Roebothan, Barbara; Colbourne, Jennifer; Maddalena, Victor; Wang, Peizhong Peter; Sun, Guang

    2016-01-01

    Background. Whether there is heterogeneity in the development of BMI from middle-age onward is still unknown. The primary aim of this study is to analyze long-term obesity and how BMI trajectories are associated with health outcomes in midlife. Methods. Latent Class Growth Modelling was used to capture the changes in BMI over time. In this study, 3070 individuals from the National Population Health Survey (NPHS), aged 40–55 years at baseline, were included. Results. Four BMI trajectory groups, “Normal-Stable” (N-S), “Overweight-Stable” (OV-S), “Obese I-Stable” (OB I-S), and “Obese II-Stable” (OB II-S), were identified. Men, persons of White ancestry, and individuals who had no postsecondary education had higher odds of being in the latter three groups. Moreover, members of the OV-S, OB I-S, and OB II-S groups experienced more asthma, arthritis, hypertension, diabetes, heart disease, cognitive impairment, and reduced self-rated overall health. Individuals in the OB II-S group were at greater risk for back problems, chronic bronchitis or emphysema, and emotional issues when compared to the N-S group. Conclusion. Understanding different BMI trajectories is important in order to identify people who are at the highest risk of developing comorbidities due to obesity and to establish programs to intervene appropriately. PMID:26925112

  19. An Alternative Humans to Mars Approach: Reducing Mission Mass with Multiple Mars Flyby Trajectories and Minimal Capability Investments

    NASA Technical Reports Server (NTRS)

    Whitley, Ryan J.; Jedrey, Richard; Landau, Damon; Ocampo, Cesar

    2015-01-01

    Mars flyby trajectories and Earth return trajectories have the potential to enable lower- cost and sustainable human exploration of Mars. Flyby and return trajectories are true minimum energy paths with low to zero post-Earth departure maneuvers. By emplacing the large crew vehicles required for human transit on these paths, the total fuel cost can be reduced. The traditional full-up repeating Earth-Mars-Earth cycler concept requires significant infrastructure, but a Mars only flyby approach minimizes mission mass and maximizes opportunities to build-up missions in a stepwise manner. In this paper multiple strategies for sending a crew of 4 to Mars orbit and back are examined. With pre-emplaced assets in Mars orbit, a transit habitat and a minimally functional Mars taxi, a complete Mars mission can be accomplished in 3 SLS launches and 2 Mars Flyby's, including Orion. While some years are better than others, ample opportunities exist within a given 15-year Earth-Mars alignment cycle. Building up a mission cadence over time, this approach can translate to Mars surface access. Risk reduction, which is always a concern for human missions, is mitigated by the use of flybys with Earth return (some of which are true free returns) capability.

  20. Small Launch Vehicle Trade Space Definition: Development of a Zero Level Mass Estimation Tool with Trajectory Validation

    NASA Technical Reports Server (NTRS)

    Waters, Eric D.

    2013-01-01

    Recent high level interest in the capability of small launch vehicles has placed significant demand on determining the trade space these vehicles occupy. This has led to the development of a zero level analysis tool that can quickly determine the minimum expected vehicle gross liftoff weight (GLOW) in terms of vehicle stage specific impulse (Isp) and propellant mass fraction (pmf) for any given payload value. Utilizing an extensive background in Earth to orbit trajectory experience a total necessary delta v the vehicle must achieve can be estimated including relevant loss terms. This foresight into expected losses allows for more specific assumptions relating to the initial estimates of thrust to weight values for each stage. This tool was further validated against a trajectory model, in this case the Program to Optimize Simulated Trajectories (POST), to determine if the initial sizing delta v was adequate to meet payload expectations. Presented here is a description of how the tool is setup and the approach the analyst must take when using the tool. Also, expected outputs which are dependent on the type of small launch vehicle being sized will be displayed. The method of validation will be discussed as well as where the sizing tool fits into the vehicle design process.

  1. Developmental trajectories of body mass index and emotional-behavioral functioning of underweight children: A longitudinal study

    PubMed Central

    Cimino, Silvia; Cerniglia, Luca; Almenara, Carlos A.; Jezek, Stanislav; Erriu, Michela; Tambelli, Renata

    2016-01-01

    Although several studies have addressed developmental trajectories from childhood to adolescence of internalizing/externalizing problems, limited attention has been given to underweight children. Two groups were recruited for this study from a community sample: underweight (Ug, N = 80, 50% female) and normal weight (NWg, N = 80, 50% female) to examine the developmental trajectories of body mass index and emotional-behavioral functioning of underweight children from the age two years, and their risk of eating disorder at early adolescence. The study was organized over four waves, each of three years. Pediatricians measured BMI, parents completed the Child Behavior Checklist (CBCL) and the Eating Disorders Inventory-Referral Form (EDI-3-RF). Our results showed that children in the two groups recorded different BMI trajectories over time. In NWg, male and female subjects started from a higher BMI at T1 than their peers. In Ug, internalizing and externalizing problems in males and females remained higher than their peers at all points of assessment. Males and females in Ug scored higher than those in NWg on EDI-3-RF total score. Our results indicate a need for effective physical and psychological assessment of underweight children in community samples to prevent psychological difficulties and eating disorders in adolescence. PMID:26806123

  2. Features of air masses associated with the deposition of Pseudomonas syringae and Botrytis cinerea by rain and snowfall.

    PubMed

    Monteil, Caroline L; Bardin, Marc; Morris, Cindy E

    2014-11-01

    Clarifying the role of precipitation in microbial dissemination is essential for elucidating the processes involved in disease emergence and spread. The ecology of Pseudomonas syringae and its presence throughout the water cycle makes it an excellent model to address this issue. In this study, 90 samples of freshly fallen rain and snow collected from 2005-2011 in France were analyzed for microbiological composition. The conditions favorable for dissemination of P. syringae by this precipitation were investigated by (i) estimating the physical properties and backward trajectories of the air masses associated with each precipitation event and by (ii) characterizing precipitation chemistry, and genetic and phenotypic structures of populations. A parallel study with the fungus Botrytis cinerea was also performed for comparison. Results showed that (i) the relationship of P. syringae to precipitation as a dissemination vector is not the same for snowfall and rainfall, whereas it is the same for B. cinerea and (ii) the occurrence of P. syringae in precipitation can be linked to electrical conductivity and pH of water, the trajectory of the air mass associated with the precipitation and certain physical conditions of the air mass (i.e. temperature, solar radiation exposure, distance traveled), whereas these predictions are different for B. cinerea. These results are pertinent to understanding microbial survival, emission sources and atmospheric processes and how they influence microbial dissemination.

  3. Features of air masses associated with the deposition of Pseudomonas syringae and Botrytis cinerea by rain and snowfall

    PubMed Central

    Monteil, Caroline L; Bardin, Marc; Morris, Cindy E

    2014-01-01

    Clarifying the role of precipitation in microbial dissemination is essential for elucidating the processes involved in disease emergence and spread. The ecology of Pseudomonas syringae and its presence throughout the water cycle makes it an excellent model to address this issue. In this study, 90 samples of freshly fallen rain and snow collected from 2005–2011 in France were analyzed for microbiological composition. The conditions favorable for dissemination of P. syringae by this precipitation were investigated by (i) estimating the physical properties and backward trajectories of the air masses associated with each precipitation event and by (ii) characterizing precipitation chemistry, and genetic and phenotypic structures of populations. A parallel study with the fungus Botrytis cinerea was also performed for comparison. Results showed that (i) the relationship of P. syringae to precipitation as a dissemination vector is not the same for snowfall and rainfall, whereas it is the same for B. cinerea and (ii) the occurrence of P. syringae in precipitation can be linked to electrical conductivity and pH of water, the trajectory of the air mass associated with the precipitation and certain physical conditions of the air mass (i.e. temperature, solar radiation exposure, distance traveled), whereas these predictions are different for B. cinerea. These results are pertinent to understanding microbial survival, emission sources and atmospheric processes and how they influence microbial dissemination. PMID:24722630

  4. Attention Deficit Disorder, Stimulant Use, and Childhood Body Mass Index Trajectory

    PubMed Central

    Bailey-Davis, Lisa; Bandeen-Roche, Karen; Pollak, Jonathan; Hirsch, Annemarie G.; Nau, Claudia; Liu, Ann Y.; Glass, Thomas A.

    2014-01-01

    BACKGROUND: Childhood attention-deficit/hyperactivity disorder (ADHD) has been associated with childhood and adult obesity, and stimulant use with delayed childhood growth, but the independent influences are unclear. No longitudinal studies have examined associations of ADHD diagnosis and stimulant use on BMI trajectories throughout childhood and adolescence. METHODS: We used longitudinal electronic health record data from the Geisinger Health System on 163 820 children ages 3 to 18 years in Pennsylvania. Random effects linear regression models were used to model BMI trajectories with increasing age in relation to ADHD diagnosis, age at first stimulant use, and stimulant use duration, while controlling for confounding variables. RESULTS: Mean (SD) age at first BMI was 8.9 (5.0) years, and children provided a mean (SD) of 3.2 (2.4) annual BMI measurements. On average, BMI trajectories showed a curvilinear relation with age. There were consistent associations of unmedicated ADHD with higher BMIs during childhood compared with those without ADHD or stimulants. Younger age at first stimulant use and longer duration of stimulant use were each associated with slower BMI growth earlier in childhood but a more rapid rebound to higher BMIs in late adolescence. CONCLUSIONS: The study provides the first longitudinal evidence that ADHD during childhood not treated with stimulants was associated with higher childhood BMIs. In contrast, ADHD treated with stimulants was associated with slower early BMI growth but a rebound later in adolescence to levels above children without a history of ADHD or stimulant use. The findings have important clinical and neurobiological implications. PMID:24639278

  5. Analytical model for contaminant mass removal by air sparging

    SciTech Connect

    Rabideau, A.J.; Blayden, J.M.

    1998-12-31

    An analytical model was developed to predict the removal of volatile organic compounds (VOCs) from ground water by air sparging (AS). The model treats the air sparging zone as a completely mixed reactor subject to the removal of dissolved contaminants by volatilization, advection, and first-order decay. Nonequilibrium desorption is approximated as a first-order mass transfer process. The model reproduces the tailing and rebound behavior often observed at AS sites, and would normally require the estimation of three site-specific parameters. Dimensional analysis demonstrates that predicting tailing can be interpreted in terms of kinetic desorption or diffusion of aqueous phase contaminants into discrete air channels. Related work is ongoing to test the model against field data.

  6. Atmospheric pollutants in Chiang Mai (Thailand) over a five-year period (2005-2009), their possible sources and relation to air mass movement

    NASA Astrophysics Data System (ADS)

    Chantara, Somporn; Sillapapiromsuk, Sopittaporn; Wiriya, Wan

    2012-12-01

    Monitoring and analysis of the chemical composition of air pollutants were conducted over a five-year period (2005-2009) in the sub-urban area of Chiang Mai, Thailand. This study aims to determine the seasonal variation of atmospheric ion species and gases, examine their correlations, identify possible sources and assess major air-flow patterns to the receptor. The dominant gas and particulate pollutants were NH3 (43-58%) and SO42- (39-48%), respectively. The annual mean concentrations of NH3 (μg m-3) in descending order were 4.08 (2009) > 3.32 (2007) > 2.68 (2008) > 2.47 (2006) and 1.87 (2005), while those of SO42- (μg m-3) were 2.60 (2007) > 2.20 (2006) > 1.95 (2009) > 1.75 (2008) and 1.26 (2005). Concentrations of particulate ions were analyzed by principle component analysis to find out the possible sources of air pollutants in this area. The first component of each year had a high loading of SO42- and NH4+, which probably came from fuel combustion and agricultural activity, respectively. K+, a tracer of biomass burning, also contributed to the first or the second components of each year. Concentrations of NH4+ and SO42- were well correlated (r > 0.777, p < 0.01), which lead to the conclusion that (NH4)2SO4 was a major compound present in this area. The 3-day backward trajectories of air mass arriving at Chiang Mai from 2005 to 2009 were analyzed using the hybrid single particle langrangian integrated trajectory (HYSPLIT) model and grouped by cluster analysis. The air mass data was analyzed for the dry season (n = 18; 100%). The trajectory of air mass in 2005 mainly originated locally (67%). In 2006, the recorded data showed that 56% of air mass was emitted from the western continental region of Thailand. In 2007, the percent ratios from the western and eastern continental areas were equal (39%). In 2008, 67% originated from the western continental area. In 2009, the recorded air mass mainly came from the western continental area (72%). In conclusion, the

  7. [Chemical Characteristics of Particulate Matters and Trajectory Influence on Air Quality in Shanghai During the Heavy Haze Episode in December, 2013].

    PubMed

    Zhou, Min; Qiao, Li-ping; Zhu, Shu-hui; Li, Li; Lou, Sheng-rong; Wang, Hong-li; Tao, Shi-kang; Huang, Cheng; Chen, Chang-hong

    2016-04-15

    Intensive haze shrouded central and eastern parts of China in Dec. 2013. In this study, the mass concentrations of gaseous and particulate pollutants, and also the chemical compositions of fine particulate matters were obtained based on in-situ measurement in Shanghai urban area. The characteristics of PM2.5 were investigated during different pollution episodes, including dust, haze, fog-haze and long-rang transport episodes. The results showed that pollution was most serious during the fog-haze episode, during which the maximum daily mass concentrations of PM10 and PM2.5 reached 536 microg x m(-3) and 411 microg x m(-3), respectively. During the fog-haze episode, the ratio of PM2.5 to PM10 was over 76.7%, suggesting that high humidity enhanced the secondary formation of NO3-, SO4(2-) and NH4+ in PM2.5. Highest concentration of Ca2+ in PM2.5 occurred during the dust episode and the proportion of primary components in PM2.5 increased obviously. Highest concentration of SO2- was observed in PM25 during the long-range transport episode, with a fast growth rate. Meanwhile, the trajectories reaching Shanghai urban area and cluster analysis during different pollution episodes were simulated by HYSPLIT model. Combined with observation data of PM2.5 in Shanghai urban area, chemical characteristics of PM2.5 in different clusters and potential source apportionment of various pollution episodes were also studied in this study. The result revealed that the air trajectories could be grouped into six clusters based on their spatial similarities. Among these clusters, cluster6 which moved fast was associated with clean air. Cluster2 and cluster3 originating from Mongolia region had strong correlations to dust pollution, along with low PM2.5/PM10 ratio and high concentration of Ca2+ in PM2.5. Compared with other clusters, cluster5 and cluster4 with slow moving speed were more favorable for reactions between particulate species and formation of secondary pollutants during transport

  8. [Chemical Characteristics of Particulate Matters and Trajectory Influence on Air Quality in Shanghai During the Heavy Haze Episode in December, 2013].

    PubMed

    Zhou, Min; Qiao, Li-ping; Zhu, Shu-hui; Li, Li; Lou, Sheng-rong; Wang, Hong-li; Tao, Shi-kang; Huang, Cheng; Chen, Chang-hong

    2016-04-15

    Intensive haze shrouded central and eastern parts of China in Dec. 2013. In this study, the mass concentrations of gaseous and particulate pollutants, and also the chemical compositions of fine particulate matters were obtained based on in-situ measurement in Shanghai urban area. The characteristics of PM2.5 were investigated during different pollution episodes, including dust, haze, fog-haze and long-rang transport episodes. The results showed that pollution was most serious during the fog-haze episode, during which the maximum daily mass concentrations of PM10 and PM2.5 reached 536 microg x m(-3) and 411 microg x m(-3), respectively. During the fog-haze episode, the ratio of PM2.5 to PM10 was over 76.7%, suggesting that high humidity enhanced the secondary formation of NO3-, SO4(2-) and NH4+ in PM2.5. Highest concentration of Ca2+ in PM2.5 occurred during the dust episode and the proportion of primary components in PM2.5 increased obviously. Highest concentration of SO2- was observed in PM25 during the long-range transport episode, with a fast growth rate. Meanwhile, the trajectories reaching Shanghai urban area and cluster analysis during different pollution episodes were simulated by HYSPLIT model. Combined with observation data of PM2.5 in Shanghai urban area, chemical characteristics of PM2.5 in different clusters and potential source apportionment of various pollution episodes were also studied in this study. The result revealed that the air trajectories could be grouped into six clusters based on their spatial similarities. Among these clusters, cluster6 which moved fast was associated with clean air. Cluster2 and cluster3 originating from Mongolia region had strong correlations to dust pollution, along with low PM2.5/PM10 ratio and high concentration of Ca2+ in PM2.5. Compared with other clusters, cluster5 and cluster4 with slow moving speed were more favorable for reactions between particulate species and formation of secondary pollutants during transport

  9. The mass and speed dependence of meteor air plasma temperatures.

    PubMed

    Jenniskens, Peter; Laux, Christophe O; Wilson, Michael A; Schaller, Emily L

    2004-01-01

    The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

  10. The mass and speed dependence of meteor air plasma temperatures

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Laux, Christophe O.; Wilson, Michael A.; Schaller, Emily L.

    2004-01-01

    The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

  11. Precipitation chemistry and corresponding transport patterns of influencing air masses at Huangshan Mountain in East China

    NASA Astrophysics Data System (ADS)

    Shi, ChunE; Deng, Xueliang; Yang, Yuanjian; Huang, Xiangrong; Wu, Biwen

    2014-09-01

    One hundred and ten samples of rainwater were collected for chemical analysis at the summit of Huangshan Mountain, a high-altitude site in East China, from July 2010 to June 2011. The volume-weighted-mean (VWM) pH for the whole sampling period was 5.03. SO{4/2-} and Ca2+ were the most abundant anion and cation, respectively. The ionic concentrations varied monthly with the highest concentrations in winter/spring and the lowest in summer. Evident inter-correlations were found among most ions, indicating the common sources for some species and fully mixing characteristics of the alpine precipitation chemistry. The VWM ratio of [SO{4/2-}]/[NO{3/-}] was 2.54, suggesting the acidity of rainwater comes from both nitric and sulfuric acids. Compared with contemporary observations at other alpine continental sites in China, the precipitation at Huangshan Mountain was the least polluted, with the lowest ionic concentrations. Trajectories to Huangshan Mountain on rainy days could be classified into six groups. The rainwater with influencing air masses originating in Mongolia was the most polluted with limited effect. The emissions of Jiangxi, Anhui, Zhejiang and Jiangsu provinces had a strong influence on the overall rain chemistry at Huangshan Mountain. The rainwater with influencing air masses from Inner Mongolia was heavily polluted by anthropogenic pollutants.

  12. On the origin and destination of atmospheric moisture and air mass over the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Xu, Xiang-De; Yang, Shuai; Zhang, Wei

    2012-12-01

    The Tibet Plateau (TP) is a key region that imposes profound impacts on the atmospheric water cycle and energy budget of Asia, even the global climate. In this work, we develop a climatology of origin (destination) of air mass and moisture transported to (from) the TP using a Lagrangian moisture diagnosis combined with the forward and backward atmospheric tracking schemes. The climatology is derived from 6-h particle positions based on 5-year (2005-2009) seasonal summer trajectory dataset from the Lagrangian particle dispersion model FLEXPART using NCEP/GFS data as input, where the regional model atmosphere was globally filled with particles. The results show that (1) the dominant origin of the moisture supplied to the TP is a narrow tropical-subtropical band in the extended Arabian Sea covering a long distance from the Indian subcontinent to the Southern Hemisphere. Two additional moisture sources are located in the northwestern part of TP and the Bay of Bengal and play a secondary role. This result indicates that the moisture transporting to the TP more depends on the Indian summer monsoon controlled by large-scale circulation. (2) The moisture departing from the TP can be transported rapidly to East Asia, including East China, Korea, Japan, and even East Pacific. The qualitative similarity between the regions of diagnosed moisture loss and the pattern of the observed precipitation highlights the robustness of the role of the TP on precipitation over East Asia. (3) In contrast to the moisture origin confined in the low level, the origin and fate of whole column air mass over the TP is largely controlled by a strong high-level Asian anticyclone. The results show that the TP is a crossroad of air mass where air enters mainly from the northwest and northeast and continues in two separate streams: one goes southwestwards over the Indian Ocean and the other southeastwards through western North Pacific. Both of them partly enter the trade wind zone, which manifests the

  13. Simple Models for Airport Delays During Transition to a Trajectory-Based Air Traffic System

    NASA Astrophysics Data System (ADS)

    Brooker, Peter

    It is now widely recognised that a paradigm shift in air traffic control concepts is needed. This requires state-of-the-art innovative technologies, making much better use of the information in the air traffic management (ATM) system. These paradigm shifts go under the names of NextGen in the USA and SESAR in Europe, which inter alia will make dramatic changes to the nature of airport operations. A vital part of moving from an existing system to a new paradigm is the operational implications of the transition process. There would be business incentives for early aircraft fitment, it is generally safer to introduce new technologies gradually, and researchers are already proposing potential transition steps to the new system. Simple queuing theory models are used to establish rough quantitative estimates of the impact of the transition to a more efficient time-based navigational and ATM system. Such models are approximate, but they do offer insight into the broad implications of system change and its significant features. 4D-equipped aircraft in essence have a contract with the airport runway and, in return, they would get priority over any other aircraft waiting for use of the runway. The main operational feature examined here is the queuing delays affecting non-4D-equipped arrivals. These get a reasonable service if the proportion of 4D-equipped aircraft is low, but this can deteriorate markedly for high proportions, and be economically unviable. Preventative measures would be to limit the additional growth of 4D-equipped flights and/or to modify their contracts to provide sufficient space for the non-4D-equipped flights to operate without excessive delays. There is a potential for non-Poisson models, for which there is little in the literature, and for more complex models, e.g. grouping a succession of 4D-equipped aircraft as a batch.

  14. EVOLUTIONARY TRAJECTORIES OF ULTRACOMPACT 'BLACK WIDOW' PULSARS WITH VERY LOW MASS COMPANIONS

    SciTech Connect

    Benvenuto, O. G.; De Vito, M. A.

    2012-07-10

    The existence of millisecond pulsars with planet-mass companions in close orbits is challenging from the stellar evolution point of view. We calculate in detail the evolution of binary systems self-consistently, including mass transfer, evaporation, and irradiation of the donor by X-ray feedback, demonstrating the existence of a new evolutionary path leading to short periods and compact donors as required by the observations of PSR J1719-1438. We also point out the alternative of an exotic nature of the companion planet-mass star.

  15. Chronic exposure of grandparents to poverty and body mass index trajectories of grandchildren: a prospective intergenerational study.

    PubMed

    Li, Miao

    2015-02-01

    In this study, I used the growth curve model to examine the association between grandparents' (first generation (G1)) life-course exposure to chronic poverty and grandchildren's (third generation (G3)) body mass index (BMI; weight (kg)/height (m)(2)) growth trajectories. This association was estimated separately for male and female grandchildren. Analyses were based on prospective data from a US longitudinal survey, the Panel Study of Income Dynamics (1968-2011), and 2 of its supplemental studies: the Child Development Supplement (1997-2011) and the Transition into Adulthood Study (1997-2011). A prospectively enrolled nationally representative cohort of 2,613 G3 youth (1,323 male, 1,290 female) sampled in the 2 supplemental studies was linked to 1,719 grandparents from the Panel Study of Income Dynamics core sample. Chronic exposure to poverty among grandparents was prospectively ascertained annually over a 30-year period prior to the collection of data on grandchildren. Findings suggested that grandparents' chronic poverty exposure was positively associated with the slope of the BMI trajectory among granddaughters (β = 0.10, 95% confidence interval: 0.03, 0.17) but not among grandsons (β = 0.02, 95% confidence interval: -0.04, 0.08). The association between grandparents' chronic poverty exposure and granddaughters' BMI growth slope remained even after controlling for parental (second generation (G2)) socioeconomic status and BMI.

  16. Enantiomeric signatures of organochlorine pesticides in Asian, trans-Pacific, and western U.S. air masses.

    PubMed

    Genualdi, Susan A; Simonich, Staci L Massey; Primbs, Toby K; Bidleman, Terry F; Jantunen, Liisa M; Ryoo, Keon-Sang; Zhu, Tong

    2009-04-15

    The enantiomeric signatures of organochlorine pesticides were measured in air masses from Okinawa, Japan and three remote locations in the Pacific Northwestern United States: Cheeka Peak Observatory (CPO), a marine boundary layer site on the Olympic Peninsula of Washington at 500 m above sea level (m.a.s.l); Mary's Peak Observatory (MPO), a site at 1250 m.a.s.l in Oregon's Coast range; and Mt. Bachelor Observatory (MBO), a site at 2763 m.a.s.l in Oregon's Cascade range. The enantiomeric signatures of composite soil samples, collected from China, South Korea, and the western U.S. were also measured. The data from chiral analysis was expressed asthe enantiomeric fraction, defined as (+) enantiomer/(sum of the (+) and (-) enantiomers), where a racemic composition has EF = 0.5. Racemic alpha-hexachlorocyclohexane (alpha-HCH) was measured in Asian air masses at Okinawa and in Chinese and South Korean soils. Nonracemic alpha-HCH (EF = 0.528 +/- 0.0048) was measured in regional air masses at CPO, and may reflect volatilization from the Pacific Ocean and regional soils. However, during trans-Pacific transport events at CPO, the alpha-HCH EFs were significantly more racemic (EF = 0.513 +/- 0.0003, p < 0.001). Racemic alpha-HCH was consistently measured at MPO and MBO in trans-Pacific air masses that had spent considerable time in the free troposphere. The alpha-HCH EFs in CPO, MPO, and MBO air masses were negatively correlated (p = 0.0017) with the amount of time the air mass spent above the boundary layer, along the 10-day back air mass trajectory, prior to being sampled. This suggests that, on the West coast of the U.S., the alpha-HCH in the free troposphere is racemic. Racemic signatures of cis- and trans-chlordane were measured in air masses at all four air sampling sites, suggesting that Asian and U.S. urban areas continue to be sources of chlordane that has not yet been biotransformed. PMID:19475954

  17. Enantiomeric Signatures of Organochlorine Pesticides in Asian, Trans-Pacific and Western U.S. Air Masses

    PubMed Central

    Genualdi, Susan A.; Massey Simonich, Staci L.; Primbs, Toby K.; Bidleman, Terry F.; Jantunen, Liisa M.; Ryoo, Keon-Sang; Zhu, Tong

    2009-01-01

    The enantiomeric signatures of organochlorine pesticides were measured in air masses from Okinawa, Japan and three remote locations in the Pacific Northwestern U.S.: Cheeka Peak Observatory (CPO), a marine boundary layer site on the Olympic Peninsula of Washington at 500 meters above sea level (m.a.s.l); Mary’s Peak Observatory (MPO), a site at 1250 m.a.s.l in Oregon’s Coast range; and Mt. Bachelor Observatory (MBO), a site at 2763 m.a.s.l in Oregon’s Cascade range. The enantiomeric signatures of composite soil samples, collected from China, South Korea, and the western U.S. were also measured. The data from chiral analysis was expressed as the enantiomeric fraction (1), defined as (+) enantiomer/(sum of the (+) and (−) enantiomers), where a racemic composition has EF = 0.5. Racemic α-hexachlorocyclohexane (α-HCH) was measured in Asian air masses at Okinawa and in Chinese and South Korean soils. Non-racemic α-HCH (EF = 0.528 ± 0.0048) was measured in regional air masses at CPO, and may reflect volatilization from the Pacific Ocean and regional soils. However, during trans-Pacific transport events at CPO, the α-HCH EFs were significantly more racemic (EF = 0.513 ± 0.0003, p < 0.001). Racemic α-HCH was consistently measured at MPO and MBO in trans-Pacific air masses that had spent considerable time in the free troposphere. The α-HCH EFs in CPO, MPO, and MBO air masses were negatively correlated (p = 0.0017) with the amount of time the air mass spent above the boundary layer, along the 10-day back air mass trajectory, prior to being sampled. This suggests that, on the West coast of the U.S., the α-HCH in the free troposphere is racemic. Racemic signatures of cis- and trans-chlordane were measured in air masses at all four air sampling sites, suggesting that Asian and U.S. urban areas continue to be sources of chlordane that has not yet been biotransformed. PMID:19475954

  18. Enantiomeric signatures of organochlorine pesticides in Asian, trans-Pacific, and western U.S. air masses.

    PubMed

    Genualdi, Susan A; Simonich, Staci L Massey; Primbs, Toby K; Bidleman, Terry F; Jantunen, Liisa M; Ryoo, Keon-Sang; Zhu, Tong

    2009-04-15

    The enantiomeric signatures of organochlorine pesticides were measured in air masses from Okinawa, Japan and three remote locations in the Pacific Northwestern United States: Cheeka Peak Observatory (CPO), a marine boundary layer site on the Olympic Peninsula of Washington at 500 m above sea level (m.a.s.l); Mary's Peak Observatory (MPO), a site at 1250 m.a.s.l in Oregon's Coast range; and Mt. Bachelor Observatory (MBO), a site at 2763 m.a.s.l in Oregon's Cascade range. The enantiomeric signatures of composite soil samples, collected from China, South Korea, and the western U.S. were also measured. The data from chiral analysis was expressed asthe enantiomeric fraction, defined as (+) enantiomer/(sum of the (+) and (-) enantiomers), where a racemic composition has EF = 0.5. Racemic alpha-hexachlorocyclohexane (alpha-HCH) was measured in Asian air masses at Okinawa and in Chinese and South Korean soils. Nonracemic alpha-HCH (EF = 0.528 +/- 0.0048) was measured in regional air masses at CPO, and may reflect volatilization from the Pacific Ocean and regional soils. However, during trans-Pacific transport events at CPO, the alpha-HCH EFs were significantly more racemic (EF = 0.513 +/- 0.0003, p < 0.001). Racemic alpha-HCH was consistently measured at MPO and MBO in trans-Pacific air masses that had spent considerable time in the free troposphere. The alpha-HCH EFs in CPO, MPO, and MBO air masses were negatively correlated (p = 0.0017) with the amount of time the air mass spent above the boundary layer, along the 10-day back air mass trajectory, prior to being sampled. This suggests that, on the West coast of the U.S., the alpha-HCH in the free troposphere is racemic. Racemic signatures of cis- and trans-chlordane were measured in air masses at all four air sampling sites, suggesting that Asian and U.S. urban areas continue to be sources of chlordane that has not yet been biotransformed.

  19. Edited by Bolling and WFB Emotion Awareness Predicts Body Mass Index Percentile Trajectories in Youth

    PubMed Central

    Whalen, Diana J.; Belden, Andrew C.; Barch, Deanna; Luby, Joan

    2015-01-01

    Objective To examine the rate of change in BMI percentile across three years in relation to emotion identification ability and brain-based reactivity in emotional processing regions. Study design A longitudinal sample of 202 youth completed three fMRI-based facial processing tasks and behavioral emotion differentiation tasks. We examined the rate of change in youth's BMI percentile as a function of reactivity in emotional processing brain regions and behavioral emotion identification tasks using multilevel modeling. Results Lower correct identification of both happiness and sadness measured behaviorally predicted increases in BMI percentiles across development whereas higher correct identification of both happiness and sadness predicted decreases in BMI percentiles, while controlling for children's pubertal status, gender, ethnicity, IQ score, exposure to antipsychotic medication, family income-to-needs ratio, externalizing, internalizing, and depressive symptoms. Greater neural activation in emotion reactivity regions to sad faces also predicted increases in BMI percentiles during development, also controlling for the above-mentioned covariates. Conclusions Findings provide longitudinal developmental data demonstrating a link between both emotion identification ability and greater neural reactivity in emotional processing regions with trajectories of BMI percentiles across childhood. PMID:26227437

  20. Air mass origin and its influence on radionuclide activities ( 7Be and 210Pb) in aerosol particles at a coastal site in the western Mediterranean

    NASA Astrophysics Data System (ADS)

    Dueñas, C.; Orza, J. A. G.; Cabello, M.; Fernández, M. C.; Cañete, S.; Pérez, M.; Gordo, E.

    2011-07-01

    Studies of radionuclide activities in aerosol particles provide a means for evaluating the integrated effects of transport and meteorology on the atmospheric loadings of substances with different sources. Measurements of aerosol mass concentration and specific activities of 7Be and 210Pb in aerosols at Málaga (36° 43' 40″ N; 4° 28' 8″ W) for the period 2000-2006 were used to obtain the relationships between radionuclide activities and airflow patterns by comparing the data grouped by air mass trajectory clusters. The average concentration values of 7Be and 210Pb over the 7 year period have been found to be 4.6 and 0.58 mBq m -3, respectively, with mean aerosol mass concentration of 53.6 μg m -3. The identified air flow types arriving at Málaga reflect the transitional location of the Iberian Peninsula and show significant differences in radionuclide activities. Air concentrations of both nuclides and the aerosol mass concentration are controlled predominantly by the synoptic scenarios leading to the entrance of dust-laden continental flows from northern Africa and the arrival of polar maritime air masses, as implied by the strong correlations found between the monthly frequencies of the different air masses and the specific activities of both radionuclides. Correlations between activity concentrations and precipitation are significant though lower than with air masses.

  1. Synoptic patterns and air mass transport during ozone episodes in northwestern Iberia.

    PubMed

    Saavedra, S; Rodríguez, A; Taboada, J J; Souto, J A; Casares, J J

    2012-12-15

    High levels of ozone are frequently measured at the Galicia (NW Iberian Peninsula) air quality monitoring stations from March to October. However, there have been very few studies on surface ozone in the northwestern Iberian Peninsula, most likely because the climate of this region is not favourable to photochemical ozone generation. The occurrence of these episodes may be related to either local-scale photochemical pollution or regional-scale transport from other polluted regions. In addition, high ozone episodes usually are developed under specific synoptic conditions. The main purposes of this study are to characterise the atmospheric conditions that lead to the ozone episodes in this region and to identify possible advection paths of ozone and precursors. A surface hourly ozone dataset (2002-2007) measured at rural sites in Galicia was analysed to identify high ozone episodes together with their associated synoptic patterns using a subjective classification with 23 different synoptic types. The synoptic weather patterns revealed that most of the episodes occur with high surface pressures centred over the British Isles and/or Central Europe while a high-altitude anticyclonic ridge crosses the Peninsula from North Africa, causing easterly or southeasterly winds. This analysis was completed with 3-day backward air mass trajectories obtained with HYSPLIT to assess the contribution of long-range transport, resulting in the following main routes: Mediterranean-Peninsular, South Atlantic-Portuguese, local and French-Cantabric.

  2. Fullerene Soot in Eastern China Air: Results from Soot Particle-Aerosol Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Wang, J.; Ge, X.; Chen, M.; Zhang, Q.; Yu, H.; Sun, Y.; Worsnop, D. R.; Collier, S.

    2015-12-01

    In this work, we present for the first time, the observation and quantification of fullerenes in ambient airborne particulate using an Aerodyne Soot Particle - Aerosol Mass Spectrometer (SP-AMS) deployed during 2015 winter in suburban Nanjing, a megacity in eastern China. The laser desorption and electron impact ionization techniques employed by the SP-AMS allow us to differentiate various fullerenes from other aerosol components. Mass spectrum of the identified fullerene soot is consisted by a series of high molecular weight carbon clusters (up to m/z of 2000 in this study), almost identical to the spectral features of commercially available fullerene soot, both with C70 and C60 clusters as the first and second most abundant species. This type of soot was observed throughout the entire study period, with an average mass loading of 0.18 μg/m3, accounting for 6.4% of the black carbon mass, 1.2% of the total organic mass. Temporal variation and diurnal pattern of fullerene soot are overall similar to those of black carbon, but are clearly different in some periods. Combining the positive matrix factorization, back-trajectory and analyses of the meteorological parameters, we identified the petrochemical industrial plants situating upwind from the sampling site, as the major source of fullerene soot. In this regard, our findings imply the ubiquitous presence of fullerene soot in ambient air of industry-influenced area, especially the oil and gas production regions. This study also offers new insights into the characterization of fullerenes from other environmental samples via the advanced SP-AMS technique.

  3. Functional forms for approximating the relative optical air mass

    NASA Astrophysics Data System (ADS)

    Rapp-Arrarás, Ígor; Domingo-Santos, Juan M.

    2011-12-01

    This article constitutes a review and systematic comparison of functional forms for approximating the air mass from the zenith to the horizon. Among them, we find the most meaningful forms in atmospheric optics, geophysics, meteorology, and solar energy science, as well as several forms arising from the study of the atmospheric delay of electromagnetic signals, whose relationship with the air mass was recently proved by the authors. In total, we have compared 26 functional forms, and the fits have been done for three atmospheric profiles, an observer at sea level, and the median wavelength of the Sun's spectral irradiance (0.7274 μm). As a result, the best of the uniparametric forms has more than three centuries of history; the best of the biparametric forms was recently introduced by one of the authors; the best of the tri- and tetraparametric forms were originally proposed for modeling the atmospheric delay of radio signals; and the best of the forms with more than four parameters is used here for the first time. On the basis of these, for the 1976 U.S. Standard Atmosphere (USSA-76), we provide one-, two-, three-, four-, and five-parameter formulas whose maximum deviations are 1.70, 2.91 × 10-1, 3.28 × 10-2, 2.49 × 10-3, and 3.24 × 10-4, respectively.

  4. Use of Chiral Signatures of Organochlorine Pesticides in Asian, Trans-Pacific, and Western U.S. Air Masses to Identify Source Regions

    NASA Astrophysics Data System (ADS)

    Simonich, S.; Genualdi, S.; Primbs, T.; Ryoo, K.; Bidleman, T.; Jantunen, L.

    2008-12-01

    Chiral signatures of organochlorine pesticides were measured in air masses on Okinawa Japan and three remote locations in the Pacific Northwestern U.S.: Cheeka Peak Observatory (CPO), a coastal site on the Olympic Peninsula of Washington at 500 m; Mary's Peak Observatory (MPO), a site at 1250 m in Oregon's Coast range; and Mt. Bachelor Observatory (MBO), a site at 2300 m in Oregon's Cascade range. The chiral signature of composite soil samples collected from agricultural areas in China and South Korea were also measured. Racemic alpha-HCH was measured in Asian air masses and soil from China and South Korea. Non-racemic (enantiomer fraction (EF) = 0.528 ± 0.0048) alpha-HCH was measured in regional air masses at CPO, a marine boundary layer site, and may reflect volatilization from the Pacific Ocean and regional soils. However, during trans-Pacific transport events at CPO, the EFs were significantly (p-value <0.001) more racemic (EF = 0.513 ± 0.0003). Racemic alpha-HCH was consistently measured in trans- Pacific air masses at MPO and MBO. The alpha-HCH EFs in CPO, MPO, and MBO air masses were positively correlated (p-value = 0.0017) with the amount of time the air mass spent above the boundary layer along the 10-day back air mass trajectory prior to being sampled. This suggests that the alpha-HCH in the free troposphere is racemic. The racemic signatures of cis and trans chlordane in air masses at all four air sampling sites suggest that Asian and U.S. urban areas continue to be sources of chlordanes that have not yet undergone biotransformation.

  5. Symmetric Trajectories for the 2N-Body Problem with Equal Masses

    NASA Astrophysics Data System (ADS)

    Terracini, Susanna; Venturelli, Andrea

    2007-06-01

    We consider the problem of 2 N bodies of equal masses in mathbb{R}^3 for the Newtonian-like weak-force potential r -σ, and we prove the existence of a family of collision-free nonplanar and nonhomographic symmetric solutions that are periodic modulo rotations. In addition, the rotation number with respect to the vertical axis ranges in a suitable interval. These solutions have the hip-hop symmetry, a generalization of that introduced in [19], for the case of many bodies and taking account of a topological constraint. The argument exploits the variational structure of the problem, and is based on the minimization of Lagrangian action on a given class of paths.

  6. The Interactive Role of Socioeconomic Status, Race/Ethnicity, and Birth Weight on Trajectories of Body Mass Index Growth in Children and Adolescents

    ERIC Educational Resources Information Center

    Danner, Fred W.; Toland, Michael D.

    2013-01-01

    This study assessed how socioeconomic status (SES), race/ethnicity, and birth weight interacted to predict differential patterns of body mass index (BMI) growth among U.S. children born in the early 1990s. Three BMI growth trajectories emerged--one above the 50th percentile across the age range of 5 to 14, one in which children rapidly became…

  7. High-Altitude Air Mass Zero Calibration of Solar Cells

    NASA Technical Reports Server (NTRS)

    Woodyard, James R.; Snyder, David B.

    2005-01-01

    Air mass zero calibration of solar cells has been carried out for several years by NASA Glenn Research Center using a Lear-25 aircraft and Langley plots. The calibration flights are carried out during early fall and late winter when the tropopause is at the lowest altitude. Measurements are made starting at about 50,000 feet and continue down to the tropopause. A joint NASA/Wayne State University program called Suntracker is underway to explore the use of weather balloon and communication technologies to characterize solar cells at elevations up to about 100 kft. The balloon flights are low-cost and can be carried out any time of the year. AMO solar cell characterization employing the mountaintop, aircraft and balloon methods are reviewed. Results of cell characterization with the Suntracker are reported and compared with the NASA Glenn Research Center aircraft method.

  8. Monitoring Trace Contaminants in Air Via Ion Trap Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Palmer, Peter T.; Karr, Dane; Pearson, Richard; Valero, Gustavo; Wong, Carla

    1995-01-01

    Recent passage of the Clean Air Act with its stricter regulation of toxic gas emissions, and the ever-growing number of applications which require faster turnaround times between sampling and analysis are two major factors which are helping to drive the development of new instrument technologies for in-situ, on-line, real-time monitoring. The ion trap, with its small size, excellent sensitivity, and tandem mass spectrometry capability is a rapidly evolving technology which is well-suited for these applications. In this paper, we describe the use of a commercial ion trap instrument for monitoring trace levels of chlorofluorocarbons (CFCs) and volatile organic compounds (VOCs) in air. A number of sample introduction devices including a direct transfer line interface, short column GC, and a cryotrapping interface are employed to achieve increasing levels of sensitivity. MS, MS/MS, and MS/MS/MS methods are compared to illustrate trade-offs between sensitivity and selectivity. Filtered Noise Field (FNF) technology is found to be an excellent means for achieving lower detection limits through selective storage of the ion(s) of interest during ionization. Figures of merit including typical sample sizes, detection limits, and response times are provided. The results indicate the potential of these techniques for atmospheric assessments, the High Speed Research Program, and advanced life support monitoring applications for NASA.

  9. Senescence or selective disappearance? Age trajectories of body mass in wild and captive populations of a small-bodied primate.

    PubMed

    Hämäläinen, Anni; Dammhahn, Melanie; Aujard, Fabienne; Eberle, Manfred; Hardy, Isabelle; Kappeler, Peter M; Perret, Martine; Schliehe-Diecks, Susanne; Kraus, Cornelia

    2014-09-22

    Classic theories of ageing consider extrinsic mortality (EM) a major factor in shaping longevity and ageing, yet most studies of functional ageing focus on species with low EM. This bias may cause overestimation of the influence of senescent declines in performance over condition-dependent mortality on demographic processes across taxa. To simultaneously investigate the roles of functional senescence (FS) and intrinsic, extrinsic and condition-dependent mortality in a species with a high predation risk in nature, we compared age trajectories of body mass (BM) in wild and captive grey mouse lemurs (Microcebus murinus) using longitudinal data (853 individuals followed through adulthood). We found evidence of non-random mortality in both settings. In captivity, the oldest animals showed senescence in their ability to regain lost BM, whereas no evidence of FS was found in the wild. Overall, captive animals lived longer, but a reversed sex bias in lifespan was observed between wild and captive populations. We suggest that even moderately condition-dependent EM may lead to negligible FS in the wild. While high EM may act to reduce the average lifespan, this evolutionary process may be counteracted by the increased fitness of the long-lived, high-quality individuals. PMID:25100693

  10. Trajectory Analysis and Optimization System

    1996-06-04

    TAOS is a general-purpose software tool capable of analyzing nearly any type of three degree-of-freedom point-mass, high-speed trajectory. Input files contain aerodynamic coefficients, propulsion data, and a trajectory description. The trajectory description divides the trajectory into segments, and within each segment, guidance rules provided by the user describe how the trajectory is computed. Output files contain tabulated trajectory information such as position, velocity, and acceleration. Parametric optimization provides a powerful method for satisfying mission-planning constraints,more » and trajectories involving more than one vehicle can be computed within a single problem.« less

  11. Background NO/sub x/ mixing ratios in air masses over the North Atlantic ocean

    SciTech Connect

    Helas, G.; Warneck, P.

    1981-08-20

    A chemiluminescence analyzer was used to measure NO/sub x/ mixing ratios at the west coast of Ireland. Two measurement modes allowed the determination of NO and NO/sub x/ = NO+NO/sub 2/. In a third mode using a molybdenum converter, higher signals were observed than was in the second mode indicating that nitrogen compounds other than NO+NO/sub 2/ are registered. They are denoted 'excess NO/sub x/'. The average NO/sub 2/ mixing ratio for a week period was 101 +- 87 pptv. In pure marine air masses identified by means of trajectory calculations, the NO/sub 2/ mixing ratios were lower and exhibited in addition a diurnal variation with nighttime values of 37 +- 6 pptv and average values of 87 +- 47 pptv. Possible origins of the diurnal variation are discussed. For such conditions, the NO mixing ratio generally was unmeasurably small, certainly less than 10 pptv. The excess NO/sub x/ is also higher during the day compared with nighttime values of about 70 pptv. Further studies are required to identify the compounds involved.

  12. Trajectories of Body Mass Index and Their Associations With Mortality Among Older Japanese: Do They Differ From Those of Western Populations?

    PubMed Central

    Murayama, Hiroshi; Liang, Jersey; Bennett, Joan M.; Shaw, Benjamin A.; Botoseneanu, Anda; Kobayashi, Erika; Fukaya, Taro; Shinkai, Shoji

    2015-01-01

    Few studies have focused on the relationship between the trajectories of long-term changes in body mass index (BMI; weight (kg)/height (m)2) and all-cause mortality in old age, particularly in non-Western populations. We evaluated this association by applying group-based mixture models to data derived from the National Survey of the Japanese Elderly, which included 4,869 adults aged 60 or more years, with up to 7 repeated observations between 1987 and 2006. Four distinct BMI trajectories were identified: “low-normal weight, decreasing” (baseline BMI = 18.7; 23.8% of sample); “mid-normal weight, decreasing” (baseline BMI = 21.9; 44.6% of sample); “high-normal weight, decreasing” (baseline BMI = 24.8; 26.5% of sample); and “overweight, stable” (baseline BMI = 28.7; 5.2% of sample). Survival analysis with an average follow-up of 13.8 years showed that trajectories of higher BMI were associated with lower mortality. In particular, relative to those with a mid-normal weight, decreasing BMI trajectory, those with an overweight, stable BMI trajectory had the lowest mortality, and those with a low-normal, decreasing BMI trajectory had the highest mortality. In sharp contrast with prior observations from Western populations, BMI changes lie primarily within the normal-weight range, and virtually no older Japanese are obese. The association between BMI trajectories and mortality varies according to the distribution of BMI within the population. PMID:26363514

  13. Influence of air mass source region on nanoparticle events and hygroscopicity in central Virginia, U.S.

    NASA Astrophysics Data System (ADS)

    O'Halloran, T. L.; Fuentes, J. D.; Collins, D. R.; Cleveland, M. J.; Keene, W. C.

    During autumn, 2006, variation in the frequency of aerosol nucleation events, as inferred from nanoparticle growth events, and associated hygroscopicity were investigated as a function of air mass transport history at a mixed deciduous forest in central Virginia, U.S. Above-canopy size distributions of aerosols between 0.012 and 0.700 μm diameter, size-resolved particle hygroscopicity at eight dry diameters between 0.012 and 0.400 μm, and cloud condensation nuclei (CCN) activity were characterized. Air mass back trajectories were clustered to identify source regions. Growth events were most frequent in fast-moving air masses (mean = 9 m s -1) that originated over the north central U.S. Under these flow regimes, mean values for preexisting sub-μm aerosol number concentrations (4700 cm -3), corresponding surface area (142 μm 2 cm -3), air temperature (6.2 °C), and relative humidity (RH, 49.4%) were relatively low compared to other regimes. Under stagnant flow conditions (mean = 3 m s -1), mean number concentrations were higher (>6000 cm -3) and size fractions <0.1 μm diameter exhibited enhanced hygroscopicity compared to other source regions. These results indicate that precursors emitted into relatively clean, cold, and dry air transported over the southeastern U.S. reacted to form condensable intermediates that subsequently produced new aerosols via nucleation and growth. This pathway was an important source for CCN. During events in October, nanoparticles were produced in greater numbers and grew more rapidly compared to November and December.

  14. Mass transfer of VOCs in laboratory-scale air sparging tank.

    PubMed

    Chao, Keh-Ping; Ong, Say Kee; Huang, Mei-Chuan

    2008-04-15

    Volatilization of VOCs was investigated using a 55-gal laboratory-scale model in which air sparging experiments were conducted with a vertical air injection well. In addition, X-ray imaging of an air sparging sand box showed air flows were in the form of air bubbles or channels depending on the size of the porous media. Air-water mass transfer was quantified using the air-water mass transfer coefficient which was determined by fitting the experimental data to a two-zone model. The two-zone model is a one-dimensional lumped model that accounts for the effects of air flow type and diffusion of VOCs in the aqueous phase. The experimental air-water mass transfer coefficients, KGa, obtained from this study ranged from 10(-2) to 10(-3)1/min. From a correlation analysis, the air-water mass transfer coefficient was found to be directly proportional to the air flow rate and the mean particle size of soil but inversely proportional to Henry's constant. The correlation results implied that the air-water mass transfer coefficient was strongly affected by the size of porous media and the air flow rates. PMID:17804158

  15. On the relationship between Arctic ice clouds and polluted air masses over the North Slope of Alaska in April 2008

    NASA Astrophysics Data System (ADS)

    Jouan, C.; Pelon, J.; Girard, E.; Ancellet, G.; Blanchet, J. P.; Delanoë, J.

    2014-02-01

    Recently, two types of ice clouds (TICs) properties have been characterized using the Indirect and Semi-Direct Aerosol Campaign (ISDAC) airborne measurements (Alaska, April 2008). TIC-2B were characterized by fewer (< 10 L-1) and larger (> 110 μm) ice crystals, and a larger ice supersaturation (> 15%) compared to TIC-1/2A. It has been hypothesized that emissions of SO2 may reduce the ice nucleating properties of ice nuclei (IN) through acidification, resulting in a smaller concentration of larger ice crystals and leading to precipitation (e.g., cloud regime TIC-2B). Here, the origin of air masses forming the ISDAC TIC-1/2A (1 April 2008) and TIC-2B (15 April 2008) is investigated using trajectory tools and satellite data. Results show that the synoptic conditions favor air masses transport from three potential SO2 emission sources into Alaska: eastern China and Siberia where anthropogenic and biomass burning emissions, respectively, are produced, and the volcanic region of the Kamchatka/Aleutians. Weather conditions allow the accumulation of pollutants from eastern China and Siberia over Alaska, most probably with the contribution of acidic volcanic aerosol during the TIC-2B period. Observation Monitoring Instrument (OMI) satellite observations reveal that SO2 concentrations in air masses forming the TIC-2B were larger than in air masses forming the TIC-1/2A. Airborne measurements show high acidity near the TIC-2B flight where humidity was low. These results support the hypothesis that acidic coating on IN could be at the origin of the formation of TIC-2B.

  16. On the relationship between Arctic ice clouds and polluted air masses over the north slope of Alaska in April 2008

    NASA Astrophysics Data System (ADS)

    Jouan, C.; Pelon, J.; Girard, E.; Ancellet, G.; Blanchet, J. P.; Delanoë, J.

    2013-02-01

    Recently, two Types of Ice Clouds (TICs) properties have been characterized using ISDAC airborne measurements (Alaska, April 2008). TIC-2B were characterized by fewer (<10 L-1) and larger (>110 μm) ice crystals, a larger ice supersaturation (>15%) and a fewer ice nuclei (IN) concentration (<2 order of magnitude) when compared to TIC-1/2A. It has been hypothesized that emissions of SO2 may reduce the ice nucleating properties of IN through acidification, resulting to a smaller concentration of larger ice crystals and leading to precipitation (e.g. cloud regime TIC-2B) because of the reduced competition for the same available moisture. Here, the origin of air masses forming the ISDAC TIC-1/2A (1 April 2008) and TIC-2B (15 April 2008) is investigated using trajectory tools and satellite data. Results show that the synoptic conditions favor air masses transport from the three potentials SO2 emission areas to Alaska: eastern China and Siberia where anthropogenic and biomass burning emission respectively are produced and the volcanic region from the Kamchatka/Aleutians. Weather conditions allow the accumulation of pollutants from eastern China/Siberia over Alaska, most probably with the contribution of acid volcanic aerosol during the TIC-2B period. OMI observations reveal that SO2 concentrations in air masses forming the TIC-2B were larger than in air masses forming the TIC-1/2A. Airborne measurements show high acidity near the TIC-2B flight where humidity was low. These results strongly support the hypothesis that acidic coating on IN are at the origin of the formation of TIC-2B.

  17. Changing air mass frequencies in Canada: potential links and implications for human health.

    PubMed

    Vanos, J K; Cakmak, S

    2014-03-01

    Many individual variables have been studied to understand climate change, yet an overall weather situation involves the consideration of many meteorological variables simultaneously at various times diurnally, seasonally, and yearly. The current study identifies a full weather situation as an air mass type using synoptic scale classification, in 30 population centres throughout Canada. Investigative analysis of long-term air mass frequency trends was completed, drawing comparisons between seasons and climate zones. We find that the changing air mass trends are highly dependent on the season and climate zone being studied, with an overall increase of moderate ('warm') air masses and decrease of polar ('cold') air masses. In the summertime, general increased moisture content is present throughout Canada, consistent with the warming air masses. The moist tropical air mass, containing the most hot and humid air, is found to increase in a statistically significant fashion in the summertime in 46% of the areas studied, which encompass six of Canada's ten largest population centres. This emphasises the need for heat adaptation and acclimatisation for a large proportion of the Canadian population. In addition, strong and significant decreases of transition/frontal passage days were found throughout Canada. This result is one of the most remarkable transition frequency results published to date due to its consistency in identifying declining trends, coinciding with research completed in the United States (US). We discuss relative results and implications to similar US air mass trend analyses, and draw upon research studies involving large-scale upper-level air flow and vortex connections to air mass changes, to small-scale meteorological and air pollution interactions. Further research is warranted to better understand such connections, and how these air masses relate to the overall and city-specific health of Canadians.

  18. Influence of trans-boundary biomass burning impacted air masses on submicron particle number concentrations and size distributions

    NASA Astrophysics Data System (ADS)

    Betha, Raghu; Zhang, Zhe; Balasubramanian, Rajasekhar

    2014-08-01

    Submicron particle number concentration (PNC) and particle size distribution (PSD) in the size range of 5.6-560 nm were investigated in Singapore from 27 June 2009 through 6 September 2009. Slightly hazy conditions lasted in Singapore from 6 to 10 August. Backward air trajectories indicated that the haze was due to the transport of biomass burning impacted air masses originating from wild forest and peat fires in Sumatra, Indonesia. Three distinct peaks in the morning (08:00-10:00), afternoon (13:00-15:00) and evening (16:00-20:00) were observed on a typical normal day. However, during the haze period no distinct morning and afternoon peaks were observed and the PNC (39,775 ± 3741 cm-3) increased by 1.5 times when compared to that during non-haze periods (26,462 ± 6017). The morning and afternoon peaks on the normal day were associated with the local rush hour traffic while the afternoon peak was induced by new particle formation (NPF). Diurnal profiles of PNCs and PSDs showed that primary particle peak diameters were large during the haze (60 nm) period when compared to that during the non-haze period (45.3 nm). NPF events observed in the afternoon period on normal days were suppressed during the haze periods due to heavy particle loading in atmosphere caused by biomass burning impacted air masses.

  19. A Variable Trajectory Plume Segment Model to Assess Ground-Level Air Concentrations and Depositions of Routine Effluent Releases from Nuclear Power Facilities.

    1986-05-27

    Version: 00 MESODIF-II, which embodies a variable trajectory plume segment atmospheric transport model, is designed to predict normalized air concentrations and deposition of radioactive, but otherwise non-reactive, effluents released from one or two levels over the same position in an xy-plane. In such a model, calculated particle trajectories vary as synoptic scale wind varies. At all sampling times, the particles are connected to form a segmented plume centerline. The lateral and vertical dimensions of themore » plume are determined by a parameterization of turbulence scale diffusion. The impetus for the development of this model arose from the need of the U. S. Nuclear Regulatory Commission to assess radiological effects resulting from routine nuclear power reactor operations, as outlined in U. S. Nuclear Regulatory Guide 1.111.« less

  20. A Variable Trajectory Plume Segment Model to Assess Ground-Level Air Concentrations and Depositions of Routine Effluent Releases from Nuclear Power Facilities.

    SciTech Connect

    1986-05-27

    Version: 00 MESODIF-II, which embodies a variable trajectory plume segment atmospheric transport model, is designed to predict normalized air concentrations and deposition of radioactive, but otherwise non-reactive, effluents released from one or two levels over the same position in an xy-plane. In such a model, calculated particle trajectories vary as synoptic scale wind varies. At all sampling times, the particles are connected to form a segmented plume centerline. The lateral and vertical dimensions of the plume are determined by a parameterization of turbulence scale diffusion. The impetus for the development of this model arose from the need of the U. S. Nuclear Regulatory Commission to assess radiological effects resulting from routine nuclear power reactor operations, as outlined in U. S. Nuclear Regulatory Guide 1.111.

  1. Microbial air quality in mass transport buses and work-related illness among bus drivers of Bangkok Mass Transit Authority.

    PubMed

    Luksamijarulkul, Pipat; Sundhiyodhin, Viboonsri; Luksamijarulkul, Soavalug; Kaewboonchoo, Orawan

    2004-06-01

    The air quality in mass transport buses, especially air-conditioned buses may affect bus drivers who work full time. Bus numbers 16, 63, 67 and 166 of the Seventh Bus Zone of Bangkok Mass Transit Authority were randomly selected to investigate for microbial air quality. Nine air-conditioned buses and 2-4 open-air buses for each number of the bus (36 air-conditioned buses and 12 open-air buses) were included. Five points of in-bus air samples in each studied bus were collected by using the Millipore A ir Tester Totally, 180 and 60 air samples collected from air-conditioned buses and open-air buses were cultured for bacterial and fungal counts. The bus drivers who drove the studied buses were interviewed towards histories of work-related illness while working. The results revealed that the mean +/- SD of bacterial counts in the studied open-air buses ranged from 358.50 +/- 146.66 CFU/m3 to 506 +/- 137.62 CFU/m3; bus number 16 had the highest level. As well as the mean +/- SD of fungal counts which ranged from 93.33 +/- 44.83 CFU/m3 to 302 +/- 294.65 CFU/m3; bus number 166 had the highest level. Whereas, the mean +/- SD of bacterial counts in the studied air-conditioned buses ranged from 115.24 +/- 136.01 CFU/m3 to 244.69 +/- 234.85 CFU/m3; bus numbers 16 and 67 had the highest level. As well as the mean +/- SD of fungal counts which rangedfrom 18.84 +/- 39.42 CFU/m3 to 96.13 +/- 234.76 CFU/m3; bus number 166 had the highest level. When 180 and 60 studied air samples were analyzed in detail, it was found that 33.33% of the air samples from open-air buses and 6.11% of air samples from air-conditioned buses had a high level of bacterial counts (> 500 CFU/m3) while 6.67% of air samples from open-air buses and 2.78% of air samples from air-conditioned buses had a high level of fungal counts (> 500 CFU/m3). Data from the history of work-related illnesses among the studied bus drivers showed that 91.67% of open-air bus drivers and 57.28% of air-conditioned bus drivers had

  2. Spontaneous change in trajectory patterns of a self-propelled oil droplet at the air-surfactant solution interface

    NASA Astrophysics Data System (ADS)

    Tanaka, Shinpei; Sogabe, Yoshimi; Nakata, Satoshi

    2015-03-01

    Trajectory-pattern formation of a self-propelled oil droplet floating on the surface of a surfactant solution in a circular dish is studied both experimentally and by simulation. The Marangoni effect induced by the dissolution of oil in the solution drives the droplet's motion. The trajectories spontaneously organize into several patterns including circular, knot-forming, back-and-forth, and irregular ones. They are either global patterns, whose center corresponds to the dish center, or other local patterns. Our simple model consisting of three forces, the driving force, the viscous resistance, and the repulsion from the boundary, successfully reproduces the global trajectory patterns including the power spectrum of the droplet speed.

  3. Cooling channels design analysis with chaotic laminar trajectory for closed cathode air-cooled PEM fuel cells using non-reacting numerical approach

    NASA Astrophysics Data System (ADS)

    N, W. Mohamed W. A.

    2015-09-01

    The thermal management of Polymer Electrolyte Membrane (PEM) fuel cells contributes directly to the overall power output of the system. For a closed cathode PEM fuel cell design, the use of air as a cooling agent is a non-conventional method due to the large heat load involved, but it offers a great advantage for minimizing the system size. Geometrical aspects of the cooling channels have been identified as the basic parameter for improved cooling performance. Numerical investigation using STAR-CCM computational fluid dynamics platform was applied for non-reacting cooling effectiveness study of various channel geometries for fuel cell application. The aspect ratio of channels and the flow trajectory are the parametric variations. A single cooling plate domain was selected with an applied heat flux of 2400 W/m2 while the cooling air are simulated at Reynolds number of 400 that corresponds to normal air flow velocities using standard 6W fans. Three channel designs of similar number of channels (20 channels) are presented here to analyze the effects of having chaotic laminar flow trajectory compared to the usual straight path trajectory. The total heat transfer between the cooling channel walls and coolant were translated into temperature distribution, maximum temperature gradient, average plate temperature and overall cooling effectiveness analyses. The numerical analysis shows that the chaotic flow promotes a 5% to 10% improvement in cooling effectiveness, depending on the single-axis or multi-axis flow paths applied. Plate temperature uniformity is also more realizable using the chaotic flow designs.

  4. High Altitude Venus Operations Concept Trajectory Design, Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Lugo, Rafael A.; Ozoroski, Thomas A.; Van Norman, John W.; Arney, Dale C.; Dec, John A.; Jones, Christopher A.; Zumwalt, Carlie H.

    2015-01-01

    A trajectory design and analysis that describes aerocapture, entry, descent, and inflation of manned and unmanned High Altitude Venus Operation Concept (HAVOC) lighter-than-air missions is presented. Mission motivation, concept of operations, and notional entry vehicle designs are presented. The initial trajectory design space is analyzed and discussed before investigating specific trajectories that are deemed representative of a feasible Venus mission. Under the project assumptions, while the high-mass crewed mission will require further research into aerodynamic decelerator technology, it was determined that the unmanned robotic mission is feasible using current technology.

  5. Distinct synoptic patterns and air masses responsible for long-range desert dust transport and sea spray in Palermo, Italy

    NASA Astrophysics Data System (ADS)

    Dimitriou, K.; Paschalidou, A. K.; Kassomenos, P. A.

    2016-09-01

    Undoubtedly, anthropogenic emissions carry a large share of the risk posed on public health by particles exposure in urban areas. However, natural emissions, in the form of desert dust and sea spray, are well known to contribute significantly to the PM load recorded in many Mediterranean environments, posing an extra risk burden on public health. In the present paper, we examine the synoptic climatology in a background station in Palermo, Italy, through K-means clustering of the mean sea-level pressure (MSLP) maps, in an attempt to associate distinct synoptic patterns with increased PM10 levels. Four-day backward trajectory analysis is then applied, in order to study the origins and pathways of air masses susceptible of PM10 episodes. It is concluded that a number of atmospheric patterns result in several kind of flows, namely south, west, and slow-moving/stagnant flows, associated with long-range dust transport and sea spray.

  6. Mathematical modeling of heat exchange between mine air and rock mass during fire

    SciTech Connect

    A.E. Krasnoshtein; B.P. Kazakov; A.V. Shalimov

    2006-05-15

    Solution of problems on heat exchange between ventilating air and rock mass and on gas admixture propagation in mine workings serve as a base for considering changes in heat-gas-air state at a mine after inflammation. The presented mathematical relations allow calculation of a varied velocity and movement direction of air flows, their temperatures and smoking conditions during fire.

  7. An objective definition of air mass types affecting Athens, Greece; the corresponding atmospheric pressure patterns and air pollution levels.

    PubMed

    Sindosi, O A; Katsoulis, B D; Bartzokas, A

    2003-08-01

    This work aims at defining characteristic air mass types that dominate in the region of Athens, Greece during the cold (November-March) and the warm (May-September) period of the year and also at evaluating the corresponding concentration levels of the main air pollutants. For each air mass type, the mean atmospheric pressure distribution (composite maps) over Europe and the Mediterranean is estimated in order to reveal the association of atmospheric circulation with air pollution levels in Athens. The data basis for this work consists of daily values of thirteen meteorological and six pollutant parameters covering the period 1993-97. The definition of the characteristic air mass types is attempted objectively by using the methods of Factor Analysis and Cluster Analysis. The results show that during the cold period of the year there are six prevailing air mass types (at least 3% of the total number of days) and six infrequent ones. The examination of the corresponding air pollution concentration levels shows that the primary air pollutants appear with increased concentrations when light or southerly winds prevail. This is usually the case when a high pressure system is located over the central Mediterranean or a low pressure system lays over south Italy, respectively. Low levels of the primary pollutants are recorded under northeasterly winds, mainly caused by a high pressure system over Ukraine. During the warm period of the year, the southwestern Asia thermal low and the subtropical anticyclone of the Atlantic Ocean affect Greece. Though these synoptic systems cause almost stagnant conditions, four main air mass types are dominant and ten others, associated with extreme weather, are infrequent. Despite the large amounts of total solar radiation characterizing this period, ozone concentrations remain at low levels in central Athens because of its destruction by nitric oxide.

  8. Air Mass Origin as a Diagnostic of Seasonally-Varying Transport into the Arctic

    NASA Astrophysics Data System (ADS)

    Orbe, C.; Waugh, D. W.; Holzer, M. B.; Newman, P. A.; Polvani, L. M.; Oman, L.; Li, F.

    2013-12-01

    While the signatures of the seasonal cycle on basic state variables such as temperature, winds and on chemical composition have been explored in depth, its signature on air mass composition has received relatively little attention. To this end, we present the first analysis of the seasonally varying transport from the northern hemisphere (NH) midlatitudes into the Arctic using rigorously defined air masses. The fractional contribution from each air mass partitions Arctic air according to where it was last in the planetary boundary layer (PBL) at midlatitudes over the Pacific and Atlantic oceans, North America, Europe, and Asia. Air mass fractions are computed using the coupled climate-chemistry model GEOSCCM subject to fixed present-day climate forcings. We find that during DJF 48% of the air in the free troposphere poleward of 60N was last at midlatitudes primarily at the Pacific and Atlantic oceans, at 20% and 10% respectively. During JJA, however, the largest contributions to Arctic air come from Asian and North American source regions, revealing that transport from the industrialized midlatitude regions dominates during boreal summer. Preliminary calculations of future air masses for a model integration subject to A1B greenhouse gases also reveal the model's climate change response in arctic air mass composition. In concert with weakened tropospheric eddy kinetic energy and a weakened Hadley cell, we find that changes in annual mean arctic air mass fractions are of the order 10%, with increased contributions from air that was last in contact with the PBL over North America and over the Atlantic and Pacific oceans. Air-mass fractions, and their changes, thus help to isolate the role of transport to changes in composition, which are not only driven by changes in chemistry and emissions but also crucially by changes in atmospheric flow.

  9. A Comparison of the Red Green Blue Air Mass Imagery and Hyperspectral Infrared Retrieved Profiles

    NASA Technical Reports Server (NTRS)

    Berndt, E. B.; Folmer, Michael; Dunion, Jason

    2014-01-01

    The Red Green Blue (RGB) Air Mass imagery is derived from multiple channels or paired channel differences. Multiple channel products typically provide additional information than a single channel can provide alone. The RGB Air Mass imagery simplifies the interpretation of temperature and moisture characteristics of air masses surrounding synoptic and mesoscale features. Despite the ease of interpretation of multiple channel products, the combination of channels and channel differences means the resulting product does not represent a quantity or physical parameter such as brightness temperature in conventional single channel satellite imagery. Without a specific quantity to reference, forecasters are often confused as to what RGB products represent. Hyperspectral infrared retrieved profiles of temperature, moisture, and ozone can provide insight about the air mass represented on the RGB Air Mass product and provide confidence in the product and representation of air masses despite the lack of a quantity to reference for interpretation. This study focuses on RGB Air Mass analysis of Hurricane Sandy as it moved north along the U.S. East Coast, while transitioning to a hybrid extratropical storm. Soundings and total column ozone retrievals were analyzed using data from the Cross-track Infrared and Advanced Technology Microwave Sounder Suite (CrIMSS) on the Suomi National Polar Orbiting Partnership satellite and the Atmospheric Infrared Sounder (AIRS) on the National Aeronautics and Space Administration Aqua satellite along with dropsondes that were collected from National Oceanic and Atmospheric Administration and Air Force research aircraft. By comparing these datasets to the RGB Air Mass, it is possible to capture quantitative information that could help in analyzing the synoptic environment enough to diagnose the onset of extratropical transition. This was done by identifying any stratospheric air intrusions (SAIs) that existed in the vicinity of Sandy as the wind

  10. Cluster Analysis of the Trajectories for Forecasted Transport of Air Pollutants using WRF and HYSPLIT Models over Istanbul for January and July, 2009

    NASA Astrophysics Data System (ADS)

    Acar, M.; Balli, C.; Caglar, F.; Tan, E.; Onol, B.; Karan, H.; Unal, Y.

    2012-04-01

    The objective of this study is to determine the risk areas which would be under the influence of particulates and gases released from a hypothetical source in Istanbul and transported by dominant atmospheric flows for months of January and July. Both January and July wind simulations are performed for the year of 2009 using the WRF model to distinguish the seasonal variations. For the initial and boundary conditions, ECMWF forecast data set is used and the results are compared to the ECMWF ERA-Interim data. Three nested domains are used over the Northwestern part of Turkey, Istanbul has been chosen as the centre point of the nested domains, which have 420x270, 385x352, and 400x310 grid points for the 9km, 3km, and 1km resolutions, respectively, and all domains have 45 vertical levels. WSM6 microphysics and YSU planetary boundary layer schemes are used for all domains. Grell-Devenyi cumulus parameterization scheme is used for the mother domain. 30s horizontal grid spaced MODIS land use data is preferred instead of USGS land use data. 24 hours forecasts are calculated starting from both the 00 UTC and 12 UTC for all days of January and July. In this study, HYSPLIT 24 hourly forward trajectory analyses are performed by using WRF results for thirteen height levels: 10m, 50m, 100m, 200m, 300m, 400m, 500m, 600m, 800m, 1000m, 1500m, 2000m, and 3000m. 5 clusters are determined using Total Spatial Variance (TSV) method for each January and July trajectory analyses. Only the trajectories for 10m, 50m, 500m, and 2000m levels are clustered in order to decide the predominant flow regime for each month. Moreover, the same cluster analyses are achieved for the WRF simulations for the mother domain, ECMWF operational data, and ERA-Interim to discuss the model performance versus observational data based on 5 cluster members. Comparisons of wind speeds for Istanbul between observations (surface/upper air), and simulations (ECMWF Interim/ECMWF forecast/WRF) revealed that both

  11. Air Mass Origin in the Arctic and its Response to Future Warming

    NASA Technical Reports Server (NTRS)

    Orbe, Clara; Newman, Paul A.; Waugh, Darryn W.; Holzer, Mark; Oman, Luke; Polvani, Lorenzo M.; Li, Feng

    2014-01-01

    We present the first climatology of air mass origin in the Arctic in terms of rigorously defined air mass fractions that partition air according to where it last contacted the planetary boundary layer (PBL). Results from a present-day climate integration of the GEOSCCM general circulation model reveal that the Arctic lower troposphere below 700 mb is dominated year round by air whose last PBL contact occurred poleward of 60degN, (Arctic air, or air of Arctic origin). By comparison, approx. 63% of the Arctic troposphere above 700 mb originates in the NH midlatitude PBL, (midlatitude air). Although seasonal changes in the total fraction of midlatitude air are small, there are dramatic changes in where that air last contacted the PBL, especially above 700 mb. Specifically, during winter air in the Arctic originates preferentially over the oceans, approx. 26% in the East Pacific, and approx. 20% in the Atlantic PBL. By comparison, during summer air in the Arctic last contacted the midlatitude PBL primarily over land, overwhelmingly so in Asia (approx. 40 %) and, to a lesser extent, in North America (approx. 24%). Seasonal changes in air-mass origin are interpreted in terms of seasonal variations in the large-scale ventilation of the midlatitude boundary layer and lower troposphere, namely changes in the midlatitude tropospheric jet and associated transient eddies during winter and large scale convective motions over midlatitudes during summer.

  12. Long-term measurements of particle number size distributions and the relationships with air mass history and source apportionment in the summer of Beijing

    NASA Astrophysics Data System (ADS)

    Wang, Z. B.; Hu, M.; Wu, Z. J.; Yue, D. L.; He, L. Y.; Huang, X. F.; Liu, X. G.; Wiedensohler, A.

    2013-02-01

    A series of long-term and temporary measurements were conducted to study the improvement of air quality in Beijing during Olympic Games period (8-24 August 2008). To evaluate actions taken to improve the air quality, comparisons of particle number and volume size distributions of August 2008 and 2004-2007 were performed. The total particle number and volume concentrations were 14 000 cm-3 and 37 μm3 cm-3 in August of 2008, respectively. These were reductions of 41% and 35% compared with the mean values of August 2004-2007. A cluster analysis on air mass history and source apportionment were performed, exploring reasons of the reduction of particle concentrations. Back trajectories were classified into five major clusters. Air mass from south direction are always associated with pollution events during the summertime of Beijing. In August 2008, the frequency of air mass arriving from south has been twice higher compared to the average of the previous years, these southerly air masses did however not result in elevated particle volume concentrations in Beijing. This result implied that the air mass history was not the key factor, explaining reduced particle number and volume concentrations during the Beijing 2008 Olympic Games. Four factors were found influencing particle concentrations using a Positive matrix factorization (PMF) model. They were identified to local and remote traffic emissions, combustion sources as well as secondary transformation. The reductions of the four sources were calculated to 47%, 44%, 43% and 30%, respectively. The significant reductions of particle number and volume concentrations may attribute to actions taken, focusing on primary emissions, especially related to the traffic and combustion sources.

  13. The Analysis of PPM Levels of Gases in Air by Photoionization Mass Spectrometry

    ERIC Educational Resources Information Center

    Driscoll, John N.; Warneck, Peter

    1973-01-01

    Discusses analysis of trace gases in air by photoionization mass spectrometer. It is shown that the necessary sensitivity can be obtained by eliminating the UV monochromator and using direct ionization with a hydrogen light source. (JP)

  14. Optimal space trajectories

    NASA Astrophysics Data System (ADS)

    Marec, J. P.

    Techniques for the optimization (in terms of minimal mass loss) of spacecraft trajectories are developed. The optimal transfer is defined; a model of the propulsion system is presented; the two-impulse Hohmann transfer between coplanar circular orbits is shown to be the optimal trajectory for that case; and the problems of optimal transfer in general, uniform, and central gravitational fields are analyzed. A number of specific cases are examined and illustrated with diagrams and graphs.

  15. Large-Scale Air Mass Characteristics Observed Over the Remote Tropical Pacific Ocean During March-April 1999: Results from PEM-Tropics B Field Experiment

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Fenn, Marta A.; Butler, Carolyn F.; Grant, William B.; Ismail, Syed; Ferrare, Richard A.; Kooi, Susan A.; Brackett, Vincent G.; Clayton, Marian B.; Avery, Melody A.

    2001-01-01

    Eighteen long-range flights over the Pacific Ocean between 38 S to 20 N and 166 E to 90 W were made by the NASA DC-8 aircraft during the NASA Pacific Exploratory Mission (PEM) Tropics B conducted from March 6 to April 18, 1999. Two lidar systems were flown on the DC-8 to remotely measure vertical profiles of ozone (O3), water vapor (H2O), aerosols, and clouds from near the surface to the upper troposphere along their flight track. In situ measurements of a wide range of gases and aerosols were made on the DC-8 for comprehensive characterization of the air and for correlation with the lidar remote measurements. The transition from northeasterly flow of Northern Hemispheric (NH) air on the northern side of the Intertropical Convergence Zone (ITCZ) to generally easterly flow of Southern Hemispheric (SH) air south of the ITCZ was accompanied by a significant decrease in O3, carbon monoxide, hydrocarbons, and aerosols and an increase in H2O. Trajectory analyses indicate that air north of the ITCZ came from Asia and/or the United States, while the air south of the ITCZ had a long residence time over the Pacific, perhaps originating over South America several weeks earlier. Air south of the South Pacific Convergence Zone (SPCZ) came rapidly from the west originating over Australia or Africa. This air had enhanced O3 and aerosols and an associated decrease in H2O. Average latitudinal and longitudinal distributions of O3 and H2O were constructed from the remote and in situ O3 and H2O data, and these distributions are compared with results from PEM-Tropics A conducted in August-October 1996. During PEM-Tropics B, low O3 air was found in the SH across the entire Pacific Basin at low latitudes. This was in strong contrast to the photochemically enhanced O3 levels found across the central and eastern Pacific low latitudes during PEM-Tropics A. Nine air mass types were identified for PEM-Tropics B based on their O3, aerosols, clouds, and potential vorticity characteristics. The

  16. A Study of the Trajectories of Projectiles.

    ERIC Educational Resources Information Center

    Grant, A. Ruari

    1990-01-01

    Described is a procedure for studying the trajectories of projectiles using ball bearings and aluminum foil. Trajectories were measured with and without the effects of air resistance. Multiflash photography was used to determine the flight paths of all objects. (KR)

  17. DNAPL REMOVAL MECHANISMS AND MASS TRANSFER CHARACTERISTICS DURING COSOLVENT-AIR FLOODING

    EPA Science Inventory

    The concurrent injection of cosolvent and air, a cosolvent-air (CA) flood was recently suggested for a dense nonaqueous phase liquid (DNAPL) remediation technology. The objectives of this study were to elucidate the DNAPL removal mechanisms of the CA flood and to quantify mass t...

  18. Experimental Determination of the Mass of Air Molecules from the Law of Atmospheres.

    ERIC Educational Resources Information Center

    Hayn, Carl H.; Galvin, Vincent, Jr.

    1979-01-01

    A gas pressure gauge has been constructed for use in a student experiment involving the law of atmospheres. From pressure data obtained at selected elevations the average mass of air molecules is determined and compared to that calculated from the molecular weights and percentages of constituents to the air. (Author/BB)

  19. Improving microbial air quality in air-conditioned mass transport buses by opening the bus exhaust ventilation fans.

    PubMed

    Luksamijarulkul, Pipat; Arunchai, Nongphon; Luksamijarulkul, Soavalug; Kaewboonchoo, Orawan

    2005-07-01

    The air quality in air-conditioned mass transport buses may affect bus drivers' health. In-bus air quality improvement with the voluntary participation of bus drivers by opening the exhaust ventilation fans in the bus was implemented in the Seventh Bus Zone of Bangkok Mass Transit Authority. Four bus numbers, including bus numbers 16, 63, 67 and 166, were randomly selected to investigate microbial air quality and to observe the effect of opening the exhaust ventilation fans in the bus. With each bus number, 9 to 10 air-conditioned buses (total, 39 air-conditioned buses) were included. In-bus air samples were collected at 5 points in each studied bus using the Millipore Air Tester. A total of 195 air samples were cultured for bacterial and fungal counts. The results reveal that the exhaust ventilation fans of 17 air-conditioned buses (43.6%) were opened to ventilate in-bus air during the cycle of the bus route. The means +/- SD of bacterial counts and fungal counts in the studied buses with opened exhaust ventilation fans (83.8 +/- 70.7 and 38.0 +/- 42.8 cfu/m3) were significantly lower than those in the studied buses without opened exhaust ventilation fans (199.6 +/- 138.8 and 294.1 +/- 178.7 cfu/m3), p < 0.0005. All the air samples collected from the studied buses with opened exhaust ventilation fans were at acceptable levels (< 500 cfu/m3) compared with 4.6% of the air samples collected from the studied buses without opened exhaust ventilation fans, which had high levels (> 500 cfu/m3). Of the studied buses with opened exhaust ventilation fans (17 buses), the bacterial and fungal counts after opening the exhaust ventilation fans (68.3 +/- 33.8 and 28.3 +/- 19.3 cfu/m3) were significantly lower than those before opening the exhaust ventilation fans (158.3 +/- 116.9 and 85.3 +/- 71.2 cfu/m3), p < 0.005.

  20. Center of mass trajectory and orientation to ankle and knee in sagittal plane is maintained with forward lean when backpack load changes during treadmill walking.

    PubMed

    Caron, Robert R; Wagenaar, Robert C; Lewis, Cara L; Saltzman, Elliot; Holt, Kenneth G

    2013-01-01

    Maintaining the normal shape and amplitude of the vertical trajectory of the center of mass (COM) during stance has been shown to maximize the efficiency of unloaded gait. Kinematic adaptations to load carriage, such as forward lean have yet to be understood in relation to COM movement. The purpose of this study is to better understand how load impacts the vertical COM(TSYS) trajectory and to clarify the impact of forward lean as it relates to the dynamics of sagittal plane COM(TSYS) movement during stance with changing load. 17 subjects walked on treadmill at a constant preferred walking velocity while nine different loads ranging from 12.5% to 40% bodyweight were systematically added and removed from a backpack. Kinematic data were collected using an Optotrak, three-dimensional motion analysis system and used to estimate position of the COM as well as segment and COM-to-joint vector orientation angles. The shape and amplitude of the COM vertical trajectory was maintained across all loaded conditions. The orientations of COM-to-ankle and -knee vectors were maintained in all loaded conditions except the heaviest load (40% BW). Results suggest that forward lean changed linearly with changes in load to maintain the COM-to-ankle and -knee vector orientations. COM vertical trajectory was maintained by a combination of invariants including lower-limb segment angles and a constant direction of toe-off impulse vector. The kinematic invariants found suggest a simplified control mechanism by which the system limits degrees of freedom and potentially minimizes torque about lower-extremity joints with added load.

  1. Does parenting help to explain socioeconomic inequalities in children's body mass index trajectories? Longitudinal analysis using the Growing Up in Scotland study

    PubMed Central

    Parkes, Alison; Sweeting, Helen; Young, Robert; Wight, Daniel

    2016-01-01

    Background Pathways leading to socioeconomic inequalities in young children's body mass index (BMI) are not well understood. This study examined whether parenting related to the physical and social context of children's food consumption helped to explain associations between maternal educational level and child BMI trajectory. Methods The study used data from 2957 families in a nationally representative birth cohort study surveyed from 2004 to 2011, with child BMI z-score measured 3 times (46, 70 and 94 months). Latent growth curve models examined associations between maternal education and BMI z-score trajectory, exploring mediating effects of parenting (positive mealtime interaction, informal meal setting and child bedroom TV) and unhealthy child diet. Results After adjusting for maternal BMI, maternal education predicted increased inequality in child BMI z-score trajectory slope over the study period. The slope index of inequality coefficient for maternal education, that is, the change in z-score associated with the lowest relative to the highest maternal education level, was 0.17, p<0.001. Indirect effects of lower maternal education on steeper BMI trajectory via parenting and/or unhealthy diet represented 89% of the total effect. Pathways via parenting and then unhealthy diet accounted for 68% of significant indirect pathways, with the remainder via unhealthy diet only. Bedroom TV was the most important parenting pathway, followed by informal meal setting. Conclusions Pathways via parenting helped to explain the emergence of inequalities in young children's BMI related to maternal education. Interventions targeting parental provision of child bedroom TV and informal meal setting might reduce these inequalities. PMID:27056682

  2. Measurement and analysis of aerosol and black carbon in the southwestern United States and Panama and their dependence on air mass origin

    NASA Astrophysics Data System (ADS)

    Junker, C.; Sheahan, J. N.; Jennings, S. G.; O'Brien, P.; Hinds, B. D.; Martinez-Twary, E.; Hansen, A. D. A.; White, C.; Garvey, D. M.; Pinnick, R. G.

    2004-07-01

    Total aerosol mass loading, aerosol absorption, and black carbon (BC) content were determined from aerosol collected on 598 quartz fiber filters at a remote, semiarid site near Orogrande, New Mexico from December 1989 to October 1995. Aerosol mass was determined by weighing filters before and after exposure, and aerosol absorption was determined by measuring the visible light transmitted through loaded filter samples and converting these measurements to aerosol absorption. BC content was determined by measuring visible light transmitted through filter samples before and after firing and converting the absorption to BC mass, assuming a BC absorption cross section of 19 m2/g in the fiber filter medium. Two analyses were then performed on each of the logged variables: an autoregressive integrating moving average (ARIMA) analysis and a decomposition analysis using an autoregressive model to accommodate first-order autocorrelation. The two analyses reveal that BC mass has no statistically significant seasonal dependence at the 5% level of significance but only random fluctuations varying around an average annual value that has a long-term decreasing trend (from 0.16 to 0.11 μg/m3 during 1990-1995). Aerosol absorption, which is dominated by BC, also displays random fluctuations about an average value, and decreases from 1.9 Mm-1 to 1.3 Mm-1 during the same period. Unlike BC, aerosol mass at the Orogrande site displays distinctly different character. The analyses reveal a pronounced seasonal dependence, but no long-term trend for aerosol mass. The seasonal indices resulting from the autoregression analysis have a minimum in January (-0.78) and maximum in June (+0.58). The geometric mean value over the 1990-1995 period for aerosol mass is 16.0 μg/m3. Since BC aerosol at the Orogrande site is a product of long-range atmospheric transport, a back trajectory analysis of air masses was conducted. Back trajectory analyses indicate that air masses traversing high population

  3. Aerial observations of air masses transported from East Asia to the Western Pacific: Vertical structure of polluted air masses

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Shiro; Ikeda, Keisuke; Hanaoka, Sayuri; Watanabe, Izumi; Arakaki, Takemitsu; Bandow, Hiroshi; Sadanaga, Yasuhiro; Kato, Shungo; Kajii, Yoshizumi; Zhang, Daizhou; Okuyama, Kikuo; Ogi, Takashi; Fujimoto, Toshiyuki; Seto, Takafumi; Shimizu, Atsushi; Sugimoto, Nobuo; Takami, Akinori

    2014-11-01

    There has been only limited information about the vertical chemical structure of the atmosphere, so far. We conducted aerial observations on 11, 12, and 14 December 2010 over the northern part of the East China Sea to analyze the spatial distribution of atmospheric pollutants from East Asia and to elucidate transformation processes of air pollutants during the long-range transport. On 11 December, a day on which Asian dust created hazy conditions, the average PM10 concentration was 40.69 μg m-3, and we observed high concentrations of chemical components such as Ca2+, NO3-, SO42-, Al, Ca, Fe, and Zn. The height of the boundary layer was about 1200 m, and most species of pollutants (except for dust particles and SO2) had accumulated within the boundary layer. In contrast, concentrations of pollutants were low in the boundary layer (up to 1000 m) on 12 December because clean Pacific air from the southeast had diluted the haze. However, we observed natural chemical components (Na+, Cl-, Al, Ca, and Fe) at 3000 m, the indication being that dust particles, including halite, were present in the lower free troposphere. On 14 December, peak concentrations of SO2 and black carbon were measured within the boundary layer (up to 700 m) and at 2300 m. The concentrations of anthropogenic chemical components such as NO3-, NH4+, and Zn were highest at 500 m, and concentrations of both anthropogenic and natural chemical components (SO42-, Pb, Ca2+, Ca, Al, and Fe) were highest at 2000 m. Thus, it was clearly indicated that the air above the East China Sea had a well-defined, layered structure below 3000 m.

  4. Persistent organic contaminants in Saharan dust air masses in West Africa, Cape Verde and the eastern Caribbean

    USGS Publications Warehouse

    Garrison, Virginia H.; Majewski, Michael S.; Foreman, William T.; Genualdi, Susan A.; Mohammed, Azad; Massey Simonich, Stacy L.

    2014-01-01

    Anthropogenic semivolatile organic compounds (SOCs) that persist in the environment, bioaccumulate, are toxic at low concentrations, and undergo long-range atmospheric transport (LRT) were identified and quantified in the atmosphere of a Saharan dust source region (Mali) and during Saharan dust incursions at downwind sites in the eastern Caribbean (U.S. Virgin Islands, Trinidad and Tobago) and Cape Verde. More organochlorine and organophosphate pesticides (OCPPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyl (PCB) congeners were detected in the Saharan dust region than at downwind sites. Seven of the 13 OCPPs detected occurred at all sites: chlordanes, chlorpyrifos, dacthal, dieldrin, endosulfans, hexachlorobenzene (HCB), and trifluralin. Total SOCs ranged from 1.9–126 ng/m3 (mean = 25 ± 34) at source and 0.05–0.71 ng/m3 (mean = 0.24 ± 0.18) at downwind sites during dust conditions. Most SOC concentrations were 1–3 orders of magnitude higher in source than downwind sites. A Saharan source was confirmed for sampled air masses at downwind sites based on dust particle elemental composition and rare earth ratios, atmospheric back trajectory models, and field observations. SOC concentrations were considerably below existing occupational and/or regulatory limits; however, few regulatory limits exist for these persistent organic compounds. Long-term effects of chronic exposure to low concentrations of SOCs are unknown, as are possible additive or synergistic effects of mixtures of SOCs, biologically active trace metals, and mineral dust particles transported together in Saharan dust air masses.

  5. Persistent organic contaminants in Saharan dust air masses in West Africa, Cape Verde and the eastern Caribbean.

    PubMed

    Garrison, V H; Majewski, M S; Foreman, W T; Genualdi, S A; Mohammed, A; Massey Simonich, S L

    2014-01-15

    Anthropogenic semivolatile organic compounds (SOCs) that persist in the environment, bioaccumulate, are toxic at low concentrations, and undergo long-range atmospheric transport (LRT) were identified and quantified in the atmosphere of a Saharan dust source region (Mali) and during Saharan dust incursions at downwind sites in the eastern Caribbean (U.S. Virgin Islands, Trinidad and Tobago) and Cape Verde. More organochlorine and organophosphate pesticides (OCPPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyl (PCB) congeners were detected in the Saharan dust region than at downwind sites. Seven of the 13 OCPPs detected occurred at all sites: chlordanes, chlorpyrifos, dacthal, dieldrin, endosulfans, hexachlorobenzene (HCB), and trifluralin. Total SOCs ranged from 1.9-126 ng/m(3) (mean = 25 ± 34) at source and 0.05-0.71 ng/m(3) (mean = 0.24 ± 0.18) at downwind sites during dust conditions. Most SOC concentrations were 1-3 orders of magnitude higher in source than downwind sites. A Saharan source was confirmed for sampled air masses at downwind sites based on dust particle elemental composition and rare earth ratios, atmospheric back trajectory models, and field observations. SOC concentrations were considerably below existing occupational and/or regulatory limits; however, few regulatory limits exist for these persistent organic compounds. Long-term effects of chronic exposure to low concentrations of SOCs are unknown, as are possible additive or synergistic effects of mixtures of SOCs, biologically active trace metals, and mineral dust particles transported together in Saharan dust air masses. PMID:24055669

  6. Characterization of volatile organic compounds (VOCs) in Asian and North American pollution plumes during INTEX-B: identification of specific Chinese air mass tracers

    NASA Astrophysics Data System (ADS)

    Barletta, B.; Meinardi, S.; Simpson, I. J.; Atlas, E. L.; Beyersdorf, A. J.; Baker, A. K.; Blake, N. J.; Yang, M.; Midyett, J. R.; Novak, B. J.; McKeachie, R. J.; Fuelberg, H. E.; Sachse, G. W.; Avery, M. A.; Campos, T.; Weinheimer, A. J.; Sherwood Rowland, F.; Blake, D. R.

    2009-03-01

    We present results from the Intercontinental Chemical Transport Experiment - Phase B (INTEX-B) aircraft mission conducted in spring 2006. By analyzing the mixing ratios of volatile organic compounds (VOCs) measured during the second part of the field campaign, together with kinematic back trajectories, we were able to identify five plumes originating from China, four plumes from other Asian regions, and three plumes from the United States. To identify specific tracers for the different air masses, we focused on characterizing the VOC composition of these different pollution plumes. The Chinese and other Asian air masses were significantly enhanced in carbonyl sulfide (OCS) and methyl chloride (CH3Cl), while all CFC replacement compounds were elevated in US plumes, particularly HCFC-134a. Although elevated mixing ratios of Halon-1211 were measured in some of the Chinese plumes, several measurements at background levels were also observed. After analyzing the VOC distribution in the Chinese pollution plumes and the correlations among selected compounds, we suggest the use of a suite of species, rather than the use of a single gas, to be used as specific tracers of Chinese air masses (namely OCS, CH3Cl, 1,2-dichloroethane, and Halon-1211). In an era of constantly changing halocarbon usage patterns, this suite of gases best reflects new emission characteristics from China.

  7. Transport Regimes of Air Masses Affecting the Tropospheric Composition of the Canadian and European Arctic During RACEPAC 2014 and NETCARE 2014/2015

    NASA Astrophysics Data System (ADS)

    Bozem, H.; Hoor, P. M.; Koellner, F.; Kunkel, D.; Schneider, J.; Schulz, C.; Herber, A. B.; Borrmann, S.; Wendisch, M.; Ehrlich, A.; Leaitch, W. R.; Willis, M. D.; Burkart, J.; Thomas, J. L.; Abbatt, J.

    2015-12-01

    The Arctic is warming much faster than any other place in the world and undergoes a rapid change dominated by a changing climate in this region. The impact of polluted air masses traveling to the Arctic from various remote sources significantly contributes to the observed climate change, in contrast there are additional local emission sources contributing to the level of pollutants (trace gases and aerosol). Processes affecting the emission and transport of these pollutants are not well understood and need to be further investigated. We present aircraft based trace gas measurements in the Arctic during RACEPAC (2014) and NETCARE (2014 and 2015) with the Polar 6 aircraft of Alfred Wegener Institute (AWI) covering an area from 134°W to 17°W and 68°N to 83°N. We focus on cloud, aerosol and general transport processes of polluted air masses into the high Arctic. Based on CO and CO2 measurements and kinematic 10-day back trajectories we analyze the transport regimes prevalent during spring (RACEPAC 2014 and NETCARE 2015) and summer (NETCARE 2014) in the observed region. Whereas the eastern part of the Canadian Arctic is affected by air masses with their origin in Asia, in the central and western parts of the Canadian and European Arctic air masses from North America are predominant at the time of the measurement. In general the more northern parts of the Arctic were relatively unaffected by pollution from mid-latitudes since air masses mostly travel within the polar dome, being quite isolated. Associated mixing ratios of CO and CO2 fit into the seasonal cycle observed at NOAA ground stations throughout the Arctic, but show a more mid-latitudinal characteristic at higher altitudes. The transition is remarkably sharp and allows for a chemical definition of the polar dome. At low altitudes, synoptic disturbances transport polluted air masses from mid-latitudes into regions of the polar dome. These air masses contribute to the Arctic pollution background, but also

  8. TAOS. Trajectory Analysis and Optimization System

    SciTech Connect

    Salguero, D.E.

    1995-12-09

    TAOS is a general-purpose software tool capable of analyzing nearly any type of three degree-of-freedom point-mass, high-speed trajectory. Input files contain aerodynamic coefficients, propulsion data, and a trajectory description. The trajectory description divides the trajectory into segments, and within each segment, guidance rules provided by the user describe how the trajectory is computed. Output files contain tabulated trajectory information such as position, velocity, and acceleration. Parametric optimization provides a powerful method for satisfying mission-planning constraints, and trajectories involving more than one vehicle can be computed within a single problem.

  9. Influence of the relative optical air mass on ultraviolet erythemal irradiance

    NASA Astrophysics Data System (ADS)

    Antón, M.; Serrano, A.; Cancillo, M. L.; García, J. A.

    2009-12-01

    The main objective of this article is to analyze the relationship between the transmissivity for ultraviolet erythemal irradiance (UVER) and the relative optical air mass at Badajoz (Southwestern Spain). Thus, a power expression between both variables is developed, which analyses in detail how atmospheric transmission is influenced by the total ozone column (TOC) and the atmospheric clearness. The period of analysis extends from 2001 to 2005. The experimental results indicate that clearness conditions play an important role in the relationship between UVER transmissivity and the relative optical air mass, while the effect of TOC is much smaller for this data set. In addition, the results show that UVER transmissivity is more sensitive to changes in atmospheric clearness than to TOC variability. Changes in TOC values higher than 15% cause UVER trasnmissivity to vary between 14% and 22%, while changes between cloud-free and overcast conditions produce variations in UVER transmissivity between 68% and 74% depending on the relative optical air mass.

  10. Thin-Film Air-Mass-Flow Sensor of Improved Design Developed

    NASA Technical Reports Server (NTRS)

    Fralick, Gustave C.; Wrbanek, John D.; Hwang, Danny P.

    2003-01-01

    Researchers at the NASA Glenn Research Center have developed a new air-mass-flow sensor to solve the problems of existing mass flow sensor designs. NASA's design consists of thin-film resistors in a Wheatstone bridge arrangement. The resistors are fabricated on a thin, constant-thickness airfoil to minimize disturbance to the airflow being measured. The following photograph shows one of NASA s prototype sensors. In comparison to other air-mass-flow sensor designs, NASA s thin-film sensor is much more robust than hot wires, causes less airflow disturbance than pitot tubes, is more accurate than vane anemometers, and is much simpler to operate than thermocouple rakes. NASA s thin-film air-mass-flow sensor works by converting the temperature difference seen at each leg of the thin-film Wheatstone bridge into a mass-flow rate. The following figure shows a schematic of this sensor with air flowing around it. The sensor operates as follows: current is applied to the bridge, which increases its temperature. If there is no flow, all the arms are heated equally, the bridge remains in balance, and there is no signal. If there is flow, the air passing over the upstream legs of the bridge reduces the temperature of the upstream legs and that leads to reduced electrical resistance for those legs. After the air has picked up heat from the upstream legs, it continues and passes over the downstream legs of the bridge. The heated air raises the temperature of these legs, increasing their electrical resistance. The resistance difference between the upstream and downstream legs unbalances the bridge, causing a voltage difference that can be amplified and calibrated to the airflow rate. Separate sensors mounted on the airfoil measure the temperature of the airflow, which is used to complete the calculation for the mass of air passing by the sensor. A current application for air-mass-flow sensors is as part of the intake system for an internal combustion engine. A mass-flow sensor is

  11. The 3D trajectory of the body centre of mass during adult human walking: evidence for a speed-curvature power law.

    PubMed

    Tesio, Luigi; Rota, Viviana; Perucca, Laura

    2011-02-24

    During straight walking, the body centre of mass (CM) follows a 3D figure-of-eight ("bow-tie") trajectory about 0.2 m long and with sizes around 0.05 m on each orthogonal axis. This was shown in 18 healthy adults walking at 0.3 to 1.4 ms⁻¹ on a force-treadmill (Tesio and Rota, 2008). Double integration of force signals can provide both the changes of mechanical energy of the CM and its 3D displacements (Tesio et al., 2010). In the same subjects, the relationship between the tangential speed of the CM, Vt, the curvature, C, and its inverse--the radius of curvature, r(c), were analyzed. A "power law" (PL) model was applied, i.e. logVt was regressed over logr(c). A PL is known to apply to the most various goal-directed planar movements (e.g. drawing), where the coefficient of logr(c), β, usually takes values around 13. When the PL was fitted to the whole dataset, β was 0.346 and variance explanation, R², was 59.8%. However, when the data were split into low- and high-curvature subsets (LC, HC, arbitrary cut-off of C=0.05 mm⁻¹, r(c)=20mm), β was 0.185 in the LC (R² 0.214) and 0.486 in the HC (R² 0.536) tracts. R² on the whole dataset increased to 0.763 if the LC-HC classification of the forward speed and their interaction entered the model. The β coefficient, the curvature C, and the pendulum-like recovery of mechanical energy were lower during the double foot-ground contact phase, compared to the single contact. Along the CM trajectory, curvature and muscle power output peaked together around the inversions of lateral direction. Non-zero torsion values were randomly distributed along 60% of the trajectory, suggesting that this is not segmented into piecewise planar tracts. It is proposed that the trajectory can be segmented into one tract that is more actively controlled (tie) where a PL fits poorly and another tract which is more ballistic (bow) where a PL fits well. Results need confirmation through more appropriate 3D PL modelling. PMID:21075377

  12. Air mass flow estimation in turbocharged diesel engines from in-cylinder pressure measurement

    SciTech Connect

    Desantes, J.M.; Galindo, J.; Guardiola, C.; Dolz, V.

    2010-01-15

    Air mass flow determination is needed for the control of current internal combustion engines. Current methods are based on specific sensors (as hot wire anemometers) or indirect estimation through manifold pressure. With the availability of cylinder pressure sensors for engine control, methods based on them can be used for replacing or complementing standard methods. Present paper uses in cylinder pressure increase during the intake stroke for inferring the trapped air mass. The method is validated on two different turbocharged diesel engines and compared with the standard methods. (author)

  13. Apparatus and method for generating large mass flow of high temperature air at hypersonic speeds

    NASA Technical Reports Server (NTRS)

    Sabol, A. P.; Stewart, R. B. (Inventor)

    1973-01-01

    High temperature, high mass air flow and a high Reynolds number test air flow in the Mach number 8-10 regime of adequate test flow duration is attained by pressurizing a ceramic-lined storage tank with air to a pressure of about 100 to 200 atmospheres. The air is heated to temperatures of 7,000 to 8,000 R prior to introduction into the tank by passing the air over an electric arc heater means. The air cools to 5,500 to 6,000 R while in the tank. A decomposable gas such as nitrous oxide or a combustible gas such as propane is injected into the tank after pressurization and the heated pressurized air in the tank is rapidly released through a Mach number 8-10 nozzle. The injected gas medium upon contact with the heated pressurized air effects an exothermic reaction which maintains the pressure and temperature of the pressurized air during the rapid release.

  14. Characterization of cumulus cloud fields using trajectories in the center of gravity versus water mass phase space: 1. Cloud tracking and phase space description

    NASA Astrophysics Data System (ADS)

    Heiblum, Reuven H.; Altaratz, Orit; Koren, Ilan; Feingold, Graham; Kostinski, Alexander B.; Khain, Alexander P.; Ovchinnikov, Mikhail; Fredj, Erick; Dagan, Guy; Pinto, Lital; Yaish, Ricki; Chen, Qian

    2016-06-01

    We study the evolution of warm convective cloud fields using large eddy simulations of continental and trade cumulus. Individual clouds are tracked a posteriori from formation to dissipation using a 3-D cloud-tracking algorithm, and results are presented in the phase space of center of gravity altitude versus cloud liquid water mass (CvM space). The CvM space is shown to contain rich information on cloud field characteristics, cloud morphology, and common cloud development pathways, together facilitating a comprehensive understanding of the cloud field. In this part we show how the meteorological (thermodynamic) conditions that determine the cloud properties are projected on the CvM phase space and how changes in the initial conditions affect the clouds' trajectories in this space. This part sets the stage for a detailed microphysical analysis that will be shown in part II.

  15. Trajectories of body mass and self-concept in black and white girls: the lingering effects of stigma.

    PubMed

    Mustillo, Sarah A; Hendrix, Kimber L; Schafer, Markus H

    2012-03-01

    As a stigmatizing condition, obesity may lead to the internalization of devalued labels and threats to self-concept. Modified labeling theory suggests that the effects of stigma may outlive direct manifestations of the discredited characteristic itself. This article considers whether obesity's effects on self-concept linger when obese youth enter the normal body mass range. Using longitudinal data from the National Growth and Health Study on 2,206 black and white girls, we estimated a parallel-process growth mixture model of body mass linked to growth models of body image discrepancy and self-esteem. We found that discrepancy was higher and self-esteem lower in formerly obese girls compared to girls always in the normal range and comparable to chronically obese girls. Neither body image discrepancy nor self-esteem rebounded in white girls despite reduction in body mass, suggesting that the effects of stigma linger. Self-esteem, but not discrepancy, did rebound in black girls.

  16. Long-term measurements of particle number size distributions and the relationships with air mass history and source apportionment in the summer of Beijing

    NASA Astrophysics Data System (ADS)

    Wang, Z. B.; Hu, M.; Wu, Z. J.; Yue, D. L.; He, L. Y.; Huang, X. F.; Liu, X. G.; Wiedensohler, A.

    2013-10-01

    A series of long-term and temporary measurements were conducted to study the improvement of air quality in Beijing during the Olympic Games period (8-24 August 2008). To evaluate actions taken to improve the air quality, comparisons of particle number and volume size distributions of August 2008 and 2004-2007 were performed. The total particle number and volume concentrations were 14 000 cm-3 and 37 μm-3 cm-3 in August of 2008, respectively. These were reductions of 41% and 35% compared with mean values of August 2004-2007. A cluster analysis on air mass history and source apportionment were performed, exploring reasons for the reduction of particle concentrations. Back trajectories were classified into five major clusters. Air masses from the south direction are always associated with pollution events during the summertime in Beijing. In August 2008, the frequency of air mass arriving from the south was 1.3 times higher compared to the average of the previous years, which however did not result in elevated particle volume concentrations in Beijing. Therefore, the reduced particle number and volume concentrations during the 2008 Beijing Olympic Games cannot be only explained by meteorological conditions. Four factors were found influencing particle concentrations using a positive matrix factorization (PMF) model. They were identified as local and remote traffic emissions, combustion sources as well as secondary transformation. The reductions of the four sources were calculated to 47%, 44%, 43% and 30%, respectively. The significant reductions of particle number and volume concentrations may attribute to actions taken, focusing on primary emissions, especially related to the traffic and combustion sources.

  17. Trajectories of body mass and self-concept in black and white girls: the lingering effects of stigma.

    PubMed

    Mustillo, Sarah A; Hendrix, Kimber L; Schafer, Markus H

    2012-03-01

    As a stigmatizing condition, obesity may lead to the internalization of devalued labels and threats to self-concept. Modified labeling theory suggests that the effects of stigma may outlive direct manifestations of the discredited characteristic itself. This article considers whether obesity's effects on self-concept linger when obese youth enter the normal body mass range. Using longitudinal data from the National Growth and Health Study on 2,206 black and white girls, we estimated a parallel-process growth mixture model of body mass linked to growth models of body image discrepancy and self-esteem. We found that discrepancy was higher and self-esteem lower in formerly obese girls compared to girls always in the normal range and comparable to chronically obese girls. Neither body image discrepancy nor self-esteem rebounded in white girls despite reduction in body mass, suggesting that the effects of stigma linger. Self-esteem, but not discrepancy, did rebound in black girls. PMID:22382717

  18. Smart tetroons for Lagrangian air-mass tracking during ACE 1

    NASA Astrophysics Data System (ADS)

    Businger, Steven; Johnson, Randy; Katzfey, Jack; Siems, Steven; Wang, Qing

    1999-05-01

    A series of "smart" tetroons was released from shipboard during the recent ACE 1 field experiment designed to monitor changes in the sulfur budget in a remote marine boundary layer (MBL) south of Tasmania, Australia. The smart tetroons were designed at NOAA Air Resources Laboratory Field Research Division to provide air parcel tracking information. The adjective smart here refers here to the fact that the buoyancy of the tetroons automatically adjusts through the action of a pump and valves when the tetroon travels vertically outside a range of pressures set prior to tetroon release. The smart tetroon design provides GPS location, barometric pressure, temperature, relative humidity, and tetroon status data via a transponder to the NCAR C-130 research aircraft flying in the vicinity of the tetroons. In this paper we will describe (1) the design and capability of the smart tetroons and their performance during the two Lagrangian experiments conducted during ACE 1, (2) the synoptic context of the Lagrangians, including the origin of the air parcels being tracked, and (3) the results of trajectory predictions derived from the National Center for Environmental Prediction (NCEP) Global Spectral Model (GSM) and Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) Division of Atmospheric Research (DAR) limited-area model.

  19. Comparison of stratospheric air parcel trajectories calculated from SSU and LIMS satellite data. [Stratospheric Sounding Unit/Limb Infrared Monitor of Stratosphere

    NASA Technical Reports Server (NTRS)

    Austin, J.

    1986-01-01

    Midstratospheric trajectories for February and March 1979 are calculated using geopotential analyses derived from limb infrared monitor of the stratosphere data. These trajectories are compared with the corresponding results using stratospheric sounding unit data. The trajectories are quasi-isentropic in that a radiation scheme is used to simply cross-isentrope flow. The results show that in disturbed conditions, quantitative agreement the trajectories, that is, within 25 great circle degrees (GCD) (one GCD about 110 km) may be valid for only 3 or 4 days, whereas during quiescent periods, quantitative agreement may last up to 10 days. By comparing trajectories calculated with different data some insight can be gained as to errors due to vertical resolution and horizontal resolution (due to infrequent sampling) in the analyzed geopotential height fields. For the disturbed trajectories described in this paper the horizontal resolution of the data was more important than vertical resolution; however, for the quiescent trajectories, which could be calculated accurately for a longer duration because of the absence of appreciable transients, the vertical resolution of the data was found to be more important than the horizontal resolution. It is speculated that these characteristics are also applicable to trajectories calculated during disturbed and quiescent periods in general. A review of some recently published trajectories shows that the qualitative conclusions of such works remains unaffected when the calculations are repeated using different data.

  20. Inert gas purgebox for Fourier transform ion cyclotron resonance mass spectrometry of air-sensitive solids

    NASA Astrophysics Data System (ADS)

    May, Michael A.; Marshall, Alan G.

    1994-03-01

    A sealed rigid ``purgebox'' makes it possible to load air- and/or moisture-sensitive solids into the solids probe inlet of a Fourier transform ion cyclotron resonance (FT/ICR) mass spectrometer. A pelletized sample is transferred (in a sealed canister) from a commercial drybox to a Lucite(R) purgebox. After the box is purged with inert gas, an attached glove manipulator is used to transfer the sample from the canister to the solids probe of the mass spectrometer. Once sealed inside the inlet, the sample is pre-evacuated and then passed into the high vacuum region of the instrument at ˜10-7 Torr. The purgebox is transparent, portable, and readily assembled/disassembled. Laser desorption FT/ICR mass spectra of the air- and moisture-sensitive solids, NbCl5. NbCl2(C5H5)2, and Zr(CH3)2(C5H5)2 are obtained without significant oxidation. The residual water vapor concentration inside the purgebox was measured as 100±20 ppm after a 90-min purge with dry nitrogen gas. High-resolution laser desorption/ionization mass spectrometry of air-sensitive solids becomes feasible with the present purgebox interface. With minor modification of the purgebox geometry, the present method could be adapted to any mass spectrometer equipped with a solid sample inlet.

  1. Airborne mass spectrometers: four decades of atmospheric and space research at the Air Force research laboratory.

    PubMed

    Viggiano, A A; Hunton, D E

    1999-11-01

    Mass spectrometry is a versatile research tool that has proved to be extremely useful for exploring the fundamental nature of the earth's atmosphere and ionosphere and in helping to solve operational problems facing the Air Force and the Department of Defense. In the past 40 years, our research group at the Air Force Research Laboratory has flown quadrupole mass spectrometers of many designs on nearly 100 sounding rockets, nine satellites, three Space Shuttles and many missions of high-altitude research aircraft and balloons. We have also used our instruments in ground-based investigations of rocket and jet engine exhaust, combustion chemistry and microwave breakdown chemistry. This paper is a review of the instrumentation and techniques needed for space research, a summary of the results from many of the experiments, and an introduction to the broad field of atmospheric and space mass spectrometry in general. PMID:10548806

  2. Airborne mass spectrometers: four decades of atmospheric and space research at the Air Force research laboratory.

    PubMed

    Viggiano, A A; Hunton, D E

    1999-11-01

    Mass spectrometry is a versatile research tool that has proved to be extremely useful for exploring the fundamental nature of the earth's atmosphere and ionosphere and in helping to solve operational problems facing the Air Force and the Department of Defense. In the past 40 years, our research group at the Air Force Research Laboratory has flown quadrupole mass spectrometers of many designs on nearly 100 sounding rockets, nine satellites, three Space Shuttles and many missions of high-altitude research aircraft and balloons. We have also used our instruments in ground-based investigations of rocket and jet engine exhaust, combustion chemistry and microwave breakdown chemistry. This paper is a review of the instrumentation and techniques needed for space research, a summary of the results from many of the experiments, and an introduction to the broad field of atmospheric and space mass spectrometry in general.

  3. 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 ...

  4. Measuring Air-water Interfacial Area for Soils Using the Mass Balance Surfactant-tracer Method

    PubMed Central

    Araujo, Juliana B.; Mainhagu, Jon; Brusseau, Mark L.

    2015-01-01

    There are several methods for conducting interfacial partitioning tracer tests to measure air-water interfacial area in porous media. One such approach is the mass balance surfactant tracer method. An advantage of the mass-balance method compared to other tracer-based methods is that a single test can produce multiple interfacial area measurements over a wide range of water saturations. The mass-balance method has been used to date only for glass beads or treated quartz sand. The purpose of this research is to investigate the effectiveness and implementability of the mass-balance method for application to more complex porous media. The results indicate that interfacial areas measured with the mass-balance method are consistent with values obtained with the miscible-displacement method. This includes results for a soil, for which solid-phase adsorption was a significant component of total tracer retention. PMID:25950136

  5. Turbulent heat and mass transfers across a thermally stratified air-water interface

    NASA Technical Reports Server (NTRS)

    Papadimitrakis, Y. A.; Hsu, Y.-H. L.; Wu, J.

    1986-01-01

    Rates of heat and mass transfer across an air-water interface were measured in a wind-wave research facility, under various wind and thermal stability conditions (unless otherwise noted, mass refers to water vapor). Heat fluxes were obtained from both the eddy correlation and the profile method, under unstable, neutral, and stable conditions. Mass fluxes were obtained only under unstable stratification from the profile and global method. Under unstable conditions the turbulent Prandtl and Schmidt numbers remain fairly constant and equal to 0.74, whereas the rate of mass transfer varies linearly with bulk Richardson number. Under stable conditions the turbulent Prandtl number rises steadily to a value of 1.4 for a bulk Richardson number of about 0.016. Results of heat and mass transfer, expressed in the form of bulk aerodynamic coefficients with friction velocity as a parameter, are also compared with field data.

  6. Measuring air-water interfacial area for soils using the mass balance surfactant-tracer method.

    PubMed

    Araujo, Juliana B; Mainhagu, Jon; Brusseau, Mark L

    2015-09-01

    There are several methods for conducting interfacial partitioning tracer tests to measure air-water interfacial area in porous media. One such approach is the mass balance surfactant tracer method. An advantage of the mass-balance method compared to other tracer-based methods is that a single test can produce multiple interfacial area measurements over a wide range of water saturations. The mass-balance method has been used to date only for glass beads or treated quartz sand. The purpose of this research is to investigate the effectiveness and implementability of the mass-balance method for application to more complex porous media. The results indicate that interfacial areas measured with the mass-balance method are consistent with values obtained with the miscible-displacement method. This includes results for a soil, for which solid-phase adsorption was a significant component of total tracer retention.

  7. Body mass trajectory, energy balance, and weight loss as determinants of health and mortality in older adults.

    PubMed

    Bales, Connie W; Buhr, Gwendolen T

    2009-01-01

    The relationship between body mass (usually measured as BMI in kg/m(2)) and healthy longevity is a major focus of study in the nutrition and aging field. Over-nutrition now rivals frailty as the major nutritional concern; the number of older adults who are obese has increased dramatically in the past 3 decades. While obesity exacerbates a host of life-threatening, age-related chronic diseases, a somewhat paradoxical finding is that being somewhat overweight in old age appears to be a benefit with regard to longevity. In our recently completed systematic review of randomized controlled weight reduction trials, we found that weight loss interventions in overweight/obese older subjects led to significant benefits for those with osteoarthritis, coronary heart disease, and type 2 diabetes mellitus, while having slightly negative effects on bone mineral density and lean body mass. In contrast to this finding, the preponderance of epidemiological evidence indicates that higher BMIs are associated with increased survival after age 65 years. Because of this contradictory state of the science, there is a critical need for further study of the relationship of weight and weight loss/gain to health in the later years of life. PMID:20054222

  8. MISR Aerosol Air Mass Type Mapping over Mega-City: Validation and Applications

    NASA Astrophysics Data System (ADS)

    Patadia, F.; Kahn, R. A.

    2010-12-01

    Most aerosol air-quality monitoring in mega-city environments is done from scattered ground stations having detailed chemical and optical sampling capabilities. Satellite instruments such as the Multi-angle Imaging SpectroRadiometer (MISR) can retrieve total-column Aerosol Optical Depth (AOD), along with some information about particle microphysical properties. Although the particle property information from MISR is much less detailed than that obtained from the ground sampling stations, the coverage is extensive, making it possible to put individual surface observations into the context of regional aerosol air mass types. This paper presents an analysis of MISR aerosol observations made coincident with aircraft and ground-based instruments during the INTEX-B field campaign. These detailed comparisons of satellite aerosol property retrievals against dedicated field measurements provide the opportunity to validate the retrievals quantitatively at a regional level, and help to improve aerosol representation in retrieval algorithms. Validation of MISR retrieved AOD and other aerosol properties over the INTEX-B study region in and around Mexico City will be presented. MISR’s ability to distinguish among aerosol air mass types will be discussed. The goal of this effort is to use the MISR aerosol property retrievals for mapping both aerosol air mass type and AOD gradients in mega-city environments over the decade-plus that MISR has made global observations.

  9. Mass spectrometry of solid samples in open air using combined laser ionization and ambient metastable ionization

    NASA Astrophysics Data System (ADS)

    He, X. N.; Xie, Z. Q.; Gao, Y.; Hu, W.; Guo, L. B.; Jiang, L.; Lu, Y. F.

    2012-01-01

    Mass spectrometry of solid samples in open air was carried out using combined laser ionization and metastable ionization time-of-flight mass spectrometry (LI-MI-TOFMS) in ambient environment for qualitative and semiquantitative (relative analyte information, not absolute information) analysis. Ambient metastable ionization using a direct analysis in realtime (DART) ion source was combined with laser ionization time-of-flight mass spectrometry (LI-TOFMS) to study the effects of combining metastable and laser ionization. A series of metallic samples from the National Institute of Standards and Technology (NIST 494, 495, 498, 499, and 500) and a pure carbon target were characterized using LI-TOFMS in open air. LI-MI-TOFMS was found to be superior to laser-induced breakdown spectroscopy (LIBS). Laser pulse energies between 10 and 200 mJ at the second harmonic (532 nm) of an Nd:YAG laser were applied in the experiment to obtain a high degree of ionization in plasmas. Higher laser pulse energy improves signal intensities of trace elements (such as Fe, Cr, Mn, Ni, Ca, Al, and Ag). Data were analyzed by numerically calculating relative sensitivity coefficients (RSCs) and limit of detections (LODs) from mass spectrometry (MS) and LIBS spectra. Different parameters, such as boiling point, ionization potential, RSC, LOD, and atomic weight, were shown to analyze the ionization and MS detection processes in open air.

  10. Loneliness trajectories.

    PubMed

    van Dulmen, Manfred H M; Goossens, Luc

    2013-12-01

    This special section brings together five studies using group-based modeling to capture developmental trajectories of loneliness from age 7 through age 20. Together, the findings from these studies provide further evidence that developmental trajectories of loneliness are likely not best understood at a continuum but reflect distinct subpopulations that differ both where they start out and how they change over time in terms of mean levels of loneliness. Furthermore, adolescents who show chronically high loneliness or increasing loneliness over time exhibit poorer psychological and physical health, including greater incidence of depressive symptoms and more frequent suicide attempts. The findings from these studies also suggest that individuals experiencing increases in loneliness with age fare worse as well in terms of both physical and psychological health.

  11. Study of single and combined mass-sensitive observables of cosmic ray induced extensive air showers

    NASA Astrophysics Data System (ADS)

    Rastegarzadeh, G.; Nemati, M.

    2016-03-01

    In this study, combinations of the global arrival time, (Δτ_{global}), pseudorapidity, and lateral density distribution (ρ_{μ}) of muons, which are three mass-sensitive observables of cosmic ray induced extensive air showers, have been used as new parameters to study the primary mass discrimination around the knee energies (100 TeV-10 PeV). This is a simulation-based study and the simulations have been performed for the KASCADE array at Karlsruhe and the Alborz-I array at Tehran to study the effect of the altitude on the quality of the primary mass discrimination. The merit factors of the single and combined three mass-sensitive observables have been calculated to compare the discrimination power of combined and single observables. We have used the CORSIKA 7.4 code to simulate the extensive air showers (EASs) sample sets. Considering all aspects of our study, it is found that the ratio of the global time to the lateral density distribution of the muons gives better results than other ratios; also in the case of single observables, the muon density gives better results compared with the other observables. Also it is shown that below 1 PeV primary energies, the ratio of the muon global time to the muon density (Δτ_{global}/ρ_{μ}) results in a better mass discrimination relative to the muon density only.

  12. Neonatal Presentation of an Air-Filled Neck Mass that Enlarges with Valsalva: A Case Report

    PubMed Central

    Patel, Jasminkumar Bharatbhai; Kilbride, Howard; Paulson, Lorien

    2015-01-01

    Branchial cleft cysts are common causes of congenital neck masses in the pediatric population. However, neonatal presentation of branchial cleft cysts is uncommon, but recognizable secondary to acute respiratory distress from airway compression or complications secondary to infection. We report a 1-day-old infant presenting with an air-filled neck mass that enlarged with Valsalva and was not associated with respiratory distress. The infant was found to have a third branchial cleft cyst with an internal opening into the pyriform sinus. The cyst was conservatively managed with endoscopic surgical decompression and cauterization of the tract and opening. We review the embryology of branchial cleft cysts and current management. PMID:26495186

  13. Air Mass Origin in the Arctic and its Response to Future Warming

    NASA Astrophysics Data System (ADS)

    Orbe, C.; Newman, P. A.; Waugh, D. W.; Holzer, M. B.; Oman, L.; Polvani, L. M.; Li, F.

    2014-12-01

    Long-range transport from Northern Hemisphere (NH) midlatitudes plays a key role in setting the distributions of trace species and aerosols in the Arctic. While comprehensive models project a strengthening and poleward shift in the midlatitude tropospheric jets in response to future warming, relatively little attention has been paid to assessing the large-scale transport response in the Arctic. A natural way to quantify transport and its future changes is in terms of rigorously defined air masses that partition air according to where it last contacted the planetary boundary layer (PBL). Here we present climatologies of Arctic air mass origin for NH winter and summer, computed from two integrations of the Goddard Earth Observing System chemistry-climate model (GEOSCCM) subject to present-day and future climate forcings. The modeled transport response to A1B greenhouse-gas induced warming reveals that in the future ~10% more air in the Arctic will originate over NH midlatitudes, with a slighter weaker albeit significant increase in winter compared to summer. Our results indicate that transport changes alone may lead to "cleaner" Arctic winters, as air will be 5-10% more likely to have last contacted the PBL over the East Pacific and the Atlantic Oceans and less likely to have originated over Europe and North America. Conversely, in future summers the air mass fractions originating over Asia and North America increase by ~10%, indicating that Arctic pollutant levels may be enhanced owing solely to changes in transport. In particular, our results suggest that more stringent emissions caps may be needed to combat enhanced transport into the Arctic from Asia, where increases in black carbon emissions have already posed concerns. Future changes in air mass fractions are interpreted in terms of large-scale circulation responses that are consistent with CMIP5 multi-model mean projections - namely, upward and poleward shifted meridional transient eddies in future winters and

  14. Measurement of mass attenuation coefficients in air by application of detector linearity tests

    NASA Astrophysics Data System (ADS)

    Peele, A. G.; Chantler, C. T.; Paterson, D.; McMahon, P. J.; Irving, T. H.; Lin, J. J.; Nugent, K. A.; Brunton, A. N.; McNulty, I.

    2002-10-01

    Accurate knowledge of x-ray mass attenuation coefficients is essential for studies as diverse as atomic physics, materials science, and radiation safety. However, a significant discrepancy exists between theoretical tabulated results for air at soft x-ray energies. We outline a precision measurement of the mass attenuation coefficients for air at various energies using two types of detectors and a simple test of detector response. We discuss whether sufficient accuracy can be obtained using this data to distinguish between competing theoretical estimates. In the process, we investigate the intensity response of two common synchrotron x-ray detectors: an x ray to optical charge-coupled device camera using a crystal scintillator and an x-ray sensitive photodiode.

  15. Estimation of whole lemon mass transfer parameters during hot air drying using different modelling methods

    NASA Astrophysics Data System (ADS)

    Torki-Harchegani, Mehdi; Ghanbarian, Davoud; Sadeghi, Morteza

    2015-08-01

    To design new dryers or improve existing drying equipments, accurate values of mass transfer parameters is of great importance. In this study, an experimental and theoretical investigation of drying whole lemons was carried out. The whole lemons were dried in a convective hot air dryer at different air temperatures (50, 60 and 75 °C) and a constant air velocity (1 m s-1). In theoretical consideration, three moisture transfer models including Dincer and Dost model, Bi- G correlation approach and conventional solution of Fick's second law of diffusion were used to determine moisture transfer parameters and predict dimensionless moisture content curves. The predicted results were then compared with the experimental data and the higher degree of prediction accuracy was achieved by the Dincer and Dost model.

  16. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways

    PubMed Central

    Liu, D. X.; Liu, Z. C.; Chen, C.; Yang, A. J.; Li, D.; Rong, M. Z.; Chen, H. L.; Kong, M. G.

    2016-01-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H+, nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2− and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios. PMID:27033381

  17. Mass transfer characteristics of bisporus mushroom ( Agaricus bisporus) slices during convective hot air drying

    NASA Astrophysics Data System (ADS)

    Ghanbarian, Davoud; Baraani Dastjerdi, Mojtaba; Torki-Harchegani, Mehdi

    2016-05-01

    An accurate understanding of moisture transfer parameters, including moisture diffusivity and moisture transfer coefficient, is essential for efficient mass transfer analysis and to design new dryers or improve existing drying equipments. The main objective of the present study was to carry out an experimental and theoretical investigation of mushroom slices drying and determine the mass transfer characteristics of the samples dried under different conditions. The mushroom slices with two thicknesses of 3 and 5 mm were dried at air temperatures of 40, 50 and 60 °C and air flow rates of 1 and 1.5 m s-1. The Dincer and Dost model was used to determine the moisture transfer parameters and predict the drying curves. It was observed that the entire drying process took place in the falling drying rate period. The obtained lag factor and Biot number indicated that the moisture transfer in the samples was controlled by both internal and external resistance. The effective moisture diffusivity and the moisture transfer coefficient increased with increasing air temperature, air flow rate and samples thickness and varied in the ranges of 6.5175 × 10-10 to 1.6726 × 10-9 m2 s-1 and 2.7715 × 10-7 to 3.5512 × 10-7 m s-1, respectively. The validation of the Dincer and Dost model indicated a good capability of the model to describe the drying curves of the mushroom slices.

  18. Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocity

    NASA Technical Reports Server (NTRS)

    Bugbee, B.; Monje, O.; Tanner, B.

    1996-01-01

    Here we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature.

  19. Quantifying energy and mass transfer in crop canopies: sensors for measurement of temperature and air velocity.

    PubMed

    Bugbee, B; Monje, O; Tanner, B

    1996-01-01

    Here we report on the in situ performance of inexpensive, miniature sensors that have increased our ability to measure mass and energy fluxes from plant canopies in controlled environments: 1. Surface temperature. Canopy temperature measurements indicate changes in stomatal aperture and thus latent and sensible heat fluxes. Infrared transducers from two manufacturers (Exergen Corporation, Newton, MA; and Everest Interscience, Tucson, AZ, USA) have recently become available. Transducer accuracy matched that of a more expensive hand-held infrared thermometer. 2. Air velocity varies above and within plant canopies and is an important component in mass and energy transfer models. We tested commercially-available needle, heat-transfer anemometers (1 x 50 mm cylinder) that consist of a fine-wire thermocouple and a heater inside a hypodermic needle. The needle is heated and wind speed determined from the temperature rise above ambient. These sensors are particularly useful in measuring the low wind speeds found within plant canopies. 3. Accurate measurements of air temperature adjacent to plant leaves facilitates transport phenomena modeling. We quantified the effect of radiation and air velocity on temperature rise in thermocouples from 10 to 500 micrometers. At high radiation loads and low wind speeds, temperature errors were as large as 7 degrees C above air temperature. PMID:11538791

  20. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways

    NASA Astrophysics Data System (ADS)

    Liu, D. X.; Liu, Z. C.; Chen, C.; Yang, A. J.; Li, D.; Rong, M. Z.; Chen, H. L.; Kong, M. G.

    2016-04-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H+, nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2‑ and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios.

  1. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways.

    PubMed

    Liu, D X; Liu, Z C; Chen, C; Yang, A J; Li, D; Rong, M Z; Chen, H L; Kong, M G

    2016-01-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H(+), nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2(-) and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios. PMID:27033381

  2. Characterization of cumulus cloud fields using trajectories in the center of gravity versus water mass phase space: 2. Aerosol effects on warm convective clouds

    NASA Astrophysics Data System (ADS)

    Heiblum, Reuven H.; Altaratz, Orit; Koren, Ilan; Feingold, Graham; Kostinski, Alexander B.; Khain, Alexander P.; Ovchinnikov, Mikhail; Fredj, Erick; Dagan, Guy; Pinto, Lital; Yaish, Ricki; Chen, Qian

    2016-06-01

    In Part I of this work a 3-D cloud tracking algorithm and phase space of center of gravity altitude versus cloud liquid water mass (CvM space) were introduced and described in detail. We showed how new physical insight can be gained by following cloud trajectories in the CvM space. Here this approach is used to investigate aerosol effects on cloud fields of warm cumuli. We show a clear effect of the aerosol loading on the shape and size of CvM clusters. We also find fundamental differences in the CvM space between simulations using bin versus bulk microphysical schemes, with the bin scheme precipitation expressing much higher sensitivity to changes in aerosol concentrations. Using the bin microphysical scheme, we find that the increase in cloud center of gravity altitude with increase in aerosol concentrations occurs for a wide range of cloud sizes. This is attributed to reduced sedimentation, increased buoyancy and vertical velocities, and increased environmental instability, all of which are tightly coupled to inhibition of precipitation processes and subsequent feedbacks of clouds on their environment. Many of the physical processes shown here are consistent with processes typically associated with cloud invigoration.

  3. Getting Bigger, Quicker? Gendered Socioeconomic Trajectories in Body Mass Index across the Adult Lifecourse: A Longitudinal Study of 21,403 Australians.

    PubMed

    Feng, Xiaoqi; Wilson, Andrew

    2015-01-01

    Do socioeconomic inequities in body mass index (BMI) widen across the adult lifecourse? BMI data for 29,104 male and 32,454 female person-years aged 15 years and older (21,403 persons in total) were extracted from the Household, Income and Labour Dynamics in Australia between 2006 and 2012. Multilevel linear regression was used to examine age and gender specific trajectories in BMI by quintiles of neighborhood socioeconomic circumstance. Models were adjusted for probable sources of confounding, including couple status, number of children resident, if somebody in the household had been pregnant in the last 12 months, the highest level of education achieved, the average household gross income, and the percentage of time in the last year spent unemployed. Approximately 9.6% of BMI variation was observed between neighborhoods. High neighborhood disadvantage was associated with 2.09 kg/m2 heavier BMI (95%CI 1.82, 2.36). At age 15-24y, socioeconomic inequity in BMI was already evident among men and women especially (22.6 kg/m2 among women in the most affluent areas compared with 25.4 kg/m2 among the most disadvantaged). Among women only, the socioeconomic gap widened from 2.8 kg/m2 at age 15-24y to 3.2 kg/m2 by age 35-44y. Geographical factors may contribute to more rapid weight gain among women living in disadvantaged neighborhoods. PMID:26496435

  4. Space trajectories

    NASA Astrophysics Data System (ADS)

    Bertachinidealmeidaprado, Antonio Fernando

    The objective of this study is to present a description of the models and methods used to calculate the optimum space trajectories, from the point of view of the smallest fuel consumption that could be used to transfer a space vehicle between two given orbits. Several options for the shaping of the dynamics, the actuators' action and optimal methods are described. Classic methods (Hohmann's transfer, bi-elliptical, etc.) and modern methods (involving gravitational capture and gravity assisted maneuvers) are stated briefly, and several references are mentioned to supply more detail.

  5. Influence of drying air parameters on mass transfer characteristics of apple slices

    NASA Astrophysics Data System (ADS)

    Beigi, Mohsen

    2016-10-01

    To efficiently design both new drying process and equipment and/or to improve the existing systems, accurate values of mass transfer characteristics are necessary. The present study aimed to investigate the influence of drying air parameters (i.e. temperature, velocity and relative humidity) on effective diffusivity and convective mass transfer coefficient of apple slices. The Dincer and Dost model was used to determine the mass transfer characteristics. The obtained Biot number indicated that the moisture transfer in the apple slices was controlled by both internal and external resistance. The effective diffusivity and mass transfer coefficient values obtained to be in the ranges of 7.13 × 10-11-7.66 × 10-10 and 1.46 × 10-7-3.39 × 10-7 m s-1, respectively and the both of them increased with increasing drying air temperature and velocity, and decreasing relative humidity. The validation of the model showed that the model predicted the experimental drying curves of the samples with a good accuracy.

  6. Influence of drying air parameters on mass transfer characteristics of apple slices

    NASA Astrophysics Data System (ADS)

    Beigi, Mohsen

    2015-12-01

    To efficiently design both new drying process and equipment and/or to improve the existing systems, accurate values of mass transfer characteristics are necessary. The present study aimed to investigate the influence of drying air parameters (i.e. temperature, velocity and relative humidity) on effective diffusivity and convective mass transfer coefficient of apple slices. The Dincer and Dost model was used to determine the mass transfer characteristics. The obtained Biot number indicated that the moisture transfer in the apple slices was controlled by both internal and external resistance. The effective diffusivity and mass transfer coefficient values obtained to be in the ranges of 7.13 × 10-11-7.66 × 10-10 and 1.46 × 10-7-3.39 × 10-7 m s-1, respectively and the both of them increased with increasing drying air temperature and velocity, and decreasing relative humidity. The validation of the model showed that the model predicted the experimental drying curves of the samples with a good accuracy.

  7. Small-size mass spectrometer for determining gases and volatile compounds in air during breathing

    NASA Astrophysics Data System (ADS)

    Kogan, V. T.; Kozlenok, A. V.; Chichagov, Yu. V.; Antonov, A. S.; Lebedev, D. S.; Bogdanov, A. A.; Moroshkin, V. S.; Berezina, A. V.; Viktorova-Leclerc, O. S.; Vlasov, S. A.; Tubol'tsev, Yu. V.

    2015-10-01

    We describe an automated mass spectrometer for diagnostics of deceases from the composition of exhaled air. It includes a capillary system, which performs a rapid direct feeding of the sample to the instrument without changing substantially its composition and serves for studying the dynamics of variation of the ratio between various components of exhaled air. The membrane system for introducing the sample is intended for determining low concentrations of volatile organic compounds which are biomarkers of pathologies. It is characterized by selective transmittance and ensures the detection limits of target compounds at the parts per million-parts per billion (ppm-ppb) level. A static mass analyzer operating on permanent magnets possesses advantages important for mobile devices as compared to its dynamic analogs: it is more reliable in operation, has a larger dynamic range, and can be used for determining the concentration of components in the mixture one-by-one or simultaneously. The curvilinear output boundary of the magnetic lens of the mass analyzer makes it possible to reduce its weight and size by 2.5 times without deteriorating the mass resolution. We report on the results of testing of the instrument and consider the possibility of its application for early detection of deceases of respiratory and blood circulation system, gastrointestinal tract, and endocrine system.

  8. A comparison of HYSPLIT backward trajectories generated from two GDAS datasets.

    PubMed

    Su, Lin; Yuan, Zibing; Fung, Jimmy C H; Lau, Alexis K H

    2015-02-15

    The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model is widely used to generate backward trajectories in given starting locations. However, differences exist between trajectories generated from the model with different input datasets. In this study, backward trajectories in Hong Kong in the entire year of 2011 are derived by HYSPLIT model. Two sets of Global Data Assimilation System (GDAS) output data associated with different horizontal and vertical resolutions (GDAS1 and GDAS0P5) are used as drivers in an attempt to quantify the differences between the results and discover the underlying reasons responsible for discrepancy. The results reveal that the significant differences between back trajectories generated from the two GDAS datasets can be mainly attributed to different vertical velocity calculation methods due to the absence of vertical velocity in GDAS0P5 dataset. The HYSPLIT trajectories are also sensitive to the horizontal and vertical resolutions of the input meteorological data, but to lesser extents. Results of cluster analysis indicate that when the air mass is from the north, northeast, or west with a long-to-medium range, the HYSPLIT backward trajectories are sensitive to the vertical advection calculation method and data resolution, whereas when the air mass is from the south or southwest with a long range, the trajectories are more likely to remain unchanged with the shifting of vertical velocity or data resolution. By comparing the vertical velocities with the observations and the performance in retrieving PM contributions from different directions, we conclude that GDAS1 dataset is more plausible in backward trajectory analysis in the Pearl River Delta.

  9. Air flow assisted ionization for remote sampling of ambient mass spectrometry and its application.

    PubMed

    He, Jiuming; Tang, Fei; Luo, Zhigang; Chen, Yi; Xu, Jing; Zhang, Ruiping; Wang, Xiaohao; Abliz, Zeper

    2011-04-15

    Ambient ionization methods are an important research area in mass spectrometry (MS) analysis. Under ambient conditions, the gas flow and atmospheric pressure significantly affect the transfer and focusing of ions. The design and implementation of air flow assisted ionization (AFAI) as a novel and effective, remote sampling method for ambient mass spectrometry are described herein. AFAI benefits from a high extracting air flow rate. A systematic investigation of the extracting air flow in the AFAI system has been carried out, and it has been demonstrated not only that it plays a role in the effective capture and remote transport of charged droplets, but also that it promotes desolvation and ion formation, and even prevents ion fragmentation during the ionization process. Moreover, the sensitivity of remote sampling ambient MS analysis was improved significantly by the AFAI method. Highly polar and nonpolar molecules, including dyes, pharmaceutical samples, explosives, drugs of abuse, protein and volatile compounds, have been successfully analyzed using AFAI-MS. The successful application of the technique to residue detection on fingers, large object analysis and remote monitoring in real time indicates its potential for the analysis of a variety of samples, especially large objects. The ability to couple this technique with most commercially available MS instruments with an API interface further enhances its broad applicability.

  10. Seasonality of new particle formation in Vienna, Austria - Influence of air mass origin and aerosol chemical composition

    NASA Astrophysics Data System (ADS)

    Wonaschütz, Anna; Demattio, Anselm; Wagner, Robert; Burkart, Julia; Zíková, Naděžda; Vodička, Petr; Ludwig, Wolfgang; Steiner, Gerhard; Schwarz, Jaroslav; Hitzenberger, Regina

    2015-10-01

    The impact of air mass origin and season on aerosol chemical composition and new particle formation and growth events (NPF events) in Vienna, Austria, is investigated using impactor samples from short-term campaigns and two long-term number size distribution datasets. The results suggest that air mass origin is most important for bulk PM concentrations, chemical composition of the coarse fraction (>1.5 μm) and the mass size distribution, and less important for chemical composition of the fine fraction (<1.5 μm). Continental air masses (crustal elements) were distinguished from air masses of marine origin (traces of sea salt). NPF events were most frequent in summer (22% of measurement days), and least frequent in winter (3% of measurement days). They were associated with above-average solar radiation and ozone concentrations, but were largely independent of PM2.5. Air mass origin was a secondary influence on NPF, largely through its association with meteorological conditions. Neither a strong dependence on the PM2.5 loading of the air masses, nor indications of a source area for NPF precursors outside the city were found.

  11. Community air monitoring for pesticides-part 2: multiresidue determination of pesticides in air by gas chromatography, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry.

    PubMed

    Hengel, Matt; Lee, P

    2014-03-01

    Two multiresidue methods were developed to determine pesticides in air collected in California. Pesticides were trapped using XAD-4 resin and extracted with ethyl acetate. Based on an analytical method from the University of California Davis Trace Analytical Laboratory, pesticides were detected by analyzing the extract by gas chromatography-mass spectrometry (GC-MS) to determine chlorothalonil, chlorthal-dimethyl, cycloate, dicloran, dicofol, EPTC, ethalfluralin, iprodione, mefenoxam, metolachlor, PCNB, permethrin, pronamide, simazine, trifluralin, and vinclozolin. A GC with a flame photometric detector was used to determine chlorpyrifos, chlorpyrifos oxon, diazinon, diazinon oxon, dimethoate, dimethoate oxon, fonophos, fonophos oxon, malathion, malathion oxon, naled, and oxydemeton. Trapping efficiencies ranged from 78 to 92 % for low level (0.5 μg) and 37-104 % for high level (50 and 100 μg) recoveries. Little to no degradation of compounds occurred over 31 days; recoveries ranged from 78 to 113 %. In the California Department of Food and Agriculture (CDFA) method, pesticides were detected by analyzing the extract by GC-MS to determine chlorothalonil, chlorpyrifos, cypermethrin, dichlorvos, dicofol, endosulfan 1, endosulfan sulfate, oxyfluorfen, permethrin, propargite, and trifluralin. A liquid chromatograph coupled to a MS was used to determine azinphos-methyl, chloropyrifos oxon, DEF, diazinon, diazinon oxon, dimethoate, dimethoate oxon, diuron, EPTC, malathion, malathion oxon, metolachlor, molinate, norflurazon, oryzalin, phosmet, propanil, simazine and thiobencarb. Trapping efficiencies for compounds determined by the CDFA method ranged from 10 to 113, 22 to 114, and 56 to 132 % for 10, 5, and 2 μg spikes, respectively. Storage tests yielded 70-170 % recovery for up to 28 days. These multiresidue methods represent flexible, sensitive, accurate, and cost-effective ways to determine residues of various pesticides in ambient air. PMID:24370860

  12. Optimization of solar cells for air mass zero operation and a study of solar cells at high temperatures, phase 2

    NASA Technical Reports Server (NTRS)

    Hovel, H.; Woodall, J. M.

    1976-01-01

    Crystal growth procedures, fabrication techniques, and theoretical analysis were developed in order to make GaAlAs-GaAs solar cell structures which exhibit high performance at air mass 0 illumination and high temperature conditions.

  13. Photochemical trajectory modeling of ozone concentrations in Hong Kong.

    PubMed

    Cheng, H R; Saunders, S M; Guo, H; Louie, P K K; Jiang, F

    2013-09-01

    In this study, tropical cyclones over the East and South China Seas were found to be the most predominant weather conditions associated with the occurrence of high ozone (O3) episodes in Hong Kong in 2005-2009. A photochemical trajectory model coupled with Master Chemical Mechanism (MCM) was adapted to simulate the O3 concentrations during two O3 pollution episodes. The results agreed well with the observed data. A representative backward air mass trajectory was used to determine the contribution of each volatile organic compound (VOC) to the O3 levels. After taking into account both reactivity and mass emission of each VOC, 10 species were found to be the key O3 precursors in Hong Kong. Further analysis identified solvent related products accounting for 70% of the modeled O3 concentration in Hong Kong. The results highlight the importance of considering together reactivity and source sector emissions in developing targeted VOC reduction for O3 abatement strategies.

  14. Evidence for widespread tropospheric Cl chemistry in free tropospheric air masses from the South China Sea

    NASA Astrophysics Data System (ADS)

    Baker, Angela K.; Sauvage, Carina; Thorenz, Ute R.; Brenninkmeijer, Carl A. M.; Oram, David E.; van Velthoven, Peter; Zahn, Andreas; Williams, Jonathan

    2015-04-01

    While the primary global atmospheric oxidant is the hydroxyl radical (OH), under certain circumstances chlorine radicals (Cl) can compete with OH and perturb the oxidative cycles of the troposphere. During flights between Bangkok, Thailand and Kuala Lumpur, Malaysia conducted over two fall/winter seasons (November 2012 - March 2013 and November 2013 - January 2014) the IAGOS-CARIBIC (www.caribic-atmospheric.com) observatory consistently encountered free tropospheric air masses (9-11 km) originating over the South China Sea which had non-methane hydrocarbon (NMHC) signatures characteristic of processing by Cl. These signatures were observed in November and December of both years, but were not seen in other months, suggesting that oxidation by Cl is a persistent seasonal feature in this region. These Cl signatures were observed over a range of ~1500 km indicating a large-scale phenomenon. In this region, where transport patterns facilitate global redistribution of pollutants and persistent deep convection creates a fast-track for cross-tropopause transport, there exists the potential for regional chemistry to have impacts further afield. Here we use observed relationships between NMHCs to estimate the significance and magnitude of Cl oxidation in this region. From the relative depletions of NMHCs in these air masses we infer OH to Cl ratios of 83±28 to 139±40 [OH]/[Cl], which we believe represents an upper limit, based on the technique employed. At a predicted average [OH] of 1.5×106 OH cm-3 this corresponds to an average (minimum) [Cl] exposure of 1-2×104 Cl cm-3 during air mass transport. Lastly, in addition to estimating Cl abundances we have used IAGOS-CARIBIC observations to elucidate whether the origin of this Cl is predominantly natural or anthropogenic.

  15. Diode laser-based air mass flux sensor for subsonic aeropropulsion inlets

    NASA Astrophysics Data System (ADS)

    Miller, Michael F.; Kessler, William J.; Allen, Mark G.

    1996-08-01

    An optical air mass flux sensor based on a compact, room-temperature diode laser in a fiber-coupled delivery system has been tested on a full-scale gas turbine engine. The sensor is based on simultaneous measurements of O 2 density and Doppler-shifted velocity along a line of sight across the inlet duct. Extensive tests spanning engine power levels from idle to full afterburner demonstrate accuracy and precision of the order of 1 2 of full scale in density, velocity, and mass flux. The precision-limited velocity at atmospheric pressure was as low as 40 cm s. Multiple data-reduction procedures are quantitatively compared to suggest optimal strategies for flight sensor packages.

  16. Light extinction by fine atmospheric particles in the White Mountains region of New Hampshire and its relationship to air mass transport.

    PubMed

    Slater, John F; Dibb, Jack E; Keim, Barry D; Talbot, Robert W

    2002-03-27

    Chemical, optical, and physical measurements of fine aerosols (aerodynamic diameter < or = 2.5 microm) have been performed at a mountaintop location adjacent to the White Mountain National Forest in northern NH, USA. A 1-month long sampling campaign was conducted at Cranmore Mountain during spring 2000. We report on the apportionment of light extinction by fine aerosols into its major chemical components, and relationships between variations in aerosol parameters and changes in air mass origin. Filter-based, 24-h integrated samples were collected and analyzed for major inorganic ions, as well as organic (OC), elemental (EC), and total carbon. Light scattering and light absorption coefficients were measured at 5-min intervals using an integrating nephelometer and a light absorption photometer. Fine particle number density was measured with a condensation particle counter. Air mass origins and transport patterns were investigated through the use of 3-day backward trajectories and a synoptic climate classification system. Two distinct transport regimes were observed: (1) flow from the north/northeast (N/NE) occurred during 9 out of 18 sample-days; and (2) flow from the west/southwest (W/SW) occurred 8 out of 18 sample-days. All measured and derived aerosol and meteorological parameters were separated into two categories based on these different flow scenarios. During W/SW flow, higher values of aerosol chemical concentration, absorption and scattering coefficients, number density, and haziness were observed compared to N/NE flow. The highest level of haziness was associated with the climate classification Frontal Atlantic Return, which brought polluted air into the region from the mid-Atlantic corridor. Fine particle mass scattering efficiencies of (NH4)2SO4 and OC were 5.35 +/- 0.42 m2 g(-1) and 1.56 +/- 0.40 m2 g(-1), respectively, when transport was out of the N/NE. When transport was from the W/SW the values were 4.94 +/- 0.68 m2 g(-1) for (NH4)2SO4 and 2.18 +/- 0

  17. Solitary fibrous tumor of the pleura manifesting as an air-containing cystic mass: radiologic and histopathologic correlation.

    PubMed

    Baek, Ji Eun; Ahn, Myeong Im; Lee, Kyo Young

    2013-01-01

    Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm that typically presents as a well-defined lobular soft tissue mass commonly arising from the pleura. We report an extremely rare case of an SFT containing air arising from the right major fissure in a 58-year-old woman. Chest CT showed an ovoid air-containing cystic mass with an internal, homogeneously enhancing solid nodule. To our knowledge, this is the first case in the literature. The histopathologic findings were correlated with the radiologic findings, and the mechanism of air retention within the tumor is discussed.

  18. Mixture model-based atmospheric air mass classification: a probabilistic view of thermodynamic profiles

    NASA Astrophysics Data System (ADS)

    Pernin, Jérôme; Vrac, Mathieu; Crevoisier, Cyril; Chédin, Alain

    2016-10-01

    Air mass classification has become an important area in synoptic climatology, simplifying the complexity of the atmosphere by dividing the atmosphere into discrete similar thermodynamic patterns. However, the constant growth of atmospheric databases in both size and complexity implies the need to develop new adaptive classifications. Here, we propose a robust unsupervised and supervised classification methodology of a large thermodynamic dataset, on a global scale and over several years, into discrete air mass groups homogeneous in both temperature and humidity that also provides underlying probability laws. Temperature and humidity at different pressure levels are aggregated into a set of cumulative distribution function (CDF) values instead of classical ones. The method is based on a Gaussian mixture model and uses the expectation-maximization (EM) algorithm to estimate the parameters of the mixture. Spatially gridded thermodynamic profiles come from ECMWF reanalyses spanning the period 2000-2009. Different aspects are investigated, such as the sensitivity of the classification process to both temporal and spatial samplings of the training dataset. Comparisons of the classifications made either by the EM algorithm or by the widely used k-means algorithm show that the former can be viewed as a generalization of the latter. Moreover, the EM algorithm delivers, for each observation, the probabilities of belonging to each class, as well as the associated uncertainty. Finally, a decision tree is proposed as a tool for interpreting the different classes, highlighting the relative importance of temperature and humidity in the classification process.

  19. [Analysis of polycyclic aromatic hydrocarbons in air samples by gas chromatography-triple quadrupole mass spectrometry].

    PubMed

    Zhao, Bo; Li, Yuqing; Zhang, Sukun; Han, Jinglei; Xu, Zhencheng; Fang, Jiande

    2014-09-01

    A method of gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-MS/MS) has been optimized for the determination of polycyclic aromatic hydrocarbons (PAHs) in air samples. In the analysis step, isotope dilution was introduced to the quantification of PAHs. The GC-MS/MS method was applied to the analysis of the real air samples around a big petrochemical power plant in South China. The results were compared with those obtained by gas chromatography coupled to mass spectrometry (GC-MS). The results showed that better selectivity and sensitivity were obtained by GC-MS/MS. It was found that the external standard of deuterated-PAHs and internal standard of hexamethyl benzene were disturbed seriously with GC-MS, and the problems were both solved effectively by GC-MS/MS. Therefore more accurate quantification results of PAHs were obtained with GC-MS/MS. For the analysis of real samples, the RSDs of relative response factors ranged from 2.60% to 15.6% in standard curves; the recoveries of deuterated-PAHs ranged from 55.2% to 82.3%; the recoveries of spiked samples ranged from 98.9% to 111%; the RSDs of parallel specimens ranged from 6.50% to 18.4%; the concentrations of field blank samples ranged from not detected to 44.3 pg/m3; and the concentrations of library blank samples ranged from not detected to 36.5 pg/m3. The study indicated that the application of GC-MS/MS on the analysis of PAHs in air samples was recommended. PMID:25752088

  20. Air mass distribution and the heterogeneity of the climate change signal in the Hudson Bay/Foxe Basin region, Canada

    NASA Astrophysics Data System (ADS)

    Leung, Andrew; Gough, William

    2016-08-01

    The linkage between changes in air mass distribution and temperature trends from 1971 to 2010 is explored in the Hudson Bay/Foxe Basin region. Statistically significant temperature increases were found of varying spatial and temporal magnitude. Concurrent statistically significant changes in air mass frequency at the same locations were also detected, particularly in the declining frequency of dry polar (DP) air. These two sets of changes were found to be linked, and we thus conclude that the heterogeneity of the climatic warming signal in the region is at least partially the result of a fundamental shift in the concurrent air mass frequency in addition to global and regional changes in radiative forcing due to increases in long-lived greenhouse gases.

  1. Trends and sources vs air mass origins in a major city in South-western Europe: Implications for air quality management.

    PubMed

    Fernández-Camacho, R; de la Rosa, J D; Sánchez de la Campa, A M

    2016-05-15

    This study presents a 17-years air quality database comprised of different parameters corresponding to the largest city in the south of Spain (Seville) where atmospheric pollution is frequently attributed to traffic emissions and is directly affected by Saharan dust outbreaks. We identify the PM10 contributions from both natural and anthropogenic sources in this area associated to different air mass origins. Hourly, daily and seasonal variation of PM10 and gaseous pollutant concentrations (CO, NO2 and SO2), all of them showing negative trends during the study period, point to the traffic as one of the main sources of air pollution in Seville. Mineral dust, secondary inorganic compounds (SIC) and trace elements showed higher concentrations under North African (NAF) air mass origins than under Atlantic. We observe a decreasing trend in all chemical components of PM10 under both types of air masses, NAF and Atlantic. Principal component analysis using more frequent air masses in the area allows the identification of five PM10 sources: crustal, regional, marine, traffic and industrial. Natural sources play a more relevant role during NAF events (20.6 μg · m(-3)) than in Atlantic episodes (13.8 μg · m(-3)). The contribution of the anthropogenic sources under NAF doubles the one under Atlantic conditions (33.6 μg · m(-3) and 15.8 μg · m(-3), respectively). During Saharan dust outbreaks the frequent accumulation of local anthropogenic pollutants in the lower atmosphere results in poor air quality and an increased risk of mortality. The results are relevant when analysing the impact of anthropogenic emissions on the exposed population in large cities. The increase in potentially toxic elements during Saharan dust outbreaks should also be taken into account when discounting the number of exceedances attributable to non-anthropogenic or natural origins.

  2. Trends and sources vs air mass origins in a major city in South-western Europe: Implications for air quality management.

    PubMed

    Fernández-Camacho, R; de la Rosa, J D; Sánchez de la Campa, A M

    2016-05-15

    This study presents a 17-years air quality database comprised of different parameters corresponding to the largest city in the south of Spain (Seville) where atmospheric pollution is frequently attributed to traffic emissions and is directly affected by Saharan dust outbreaks. We identify the PM10 contributions from both natural and anthropogenic sources in this area associated to different air mass origins. Hourly, daily and seasonal variation of PM10 and gaseous pollutant concentrations (CO, NO2 and SO2), all of them showing negative trends during the study period, point to the traffic as one of the main sources of air pollution in Seville. Mineral dust, secondary inorganic compounds (SIC) and trace elements showed higher concentrations under North African (NAF) air mass origins than under Atlantic. We observe a decreasing trend in all chemical components of PM10 under both types of air masses, NAF and Atlantic. Principal component analysis using more frequent air masses in the area allows the identification of five PM10 sources: crustal, regional, marine, traffic and industrial. Natural sources play a more relevant role during NAF events (20.6 μg · m(-3)) than in Atlantic episodes (13.8 μg · m(-3)). The contribution of the anthropogenic sources under NAF doubles the one under Atlantic conditions (33.6 μg · m(-3) and 15.8 μg · m(-3), respectively). During Saharan dust outbreaks the frequent accumulation of local anthropogenic pollutants in the lower atmosphere results in poor air quality and an increased risk of mortality. The results are relevant when analysing the impact of anthropogenic emissions on the exposed population in large cities. The increase in potentially toxic elements during Saharan dust outbreaks should also be taken into account when discounting the number of exceedances attributable to non-anthropogenic or natural origins. PMID:26930305

  3. Quantification of methane in humid air and exhaled breath using selected ion flow tube mass spectrometry.

    PubMed

    Dryahina, Kseniya; Smith, D; Spanel, P

    2010-05-15

    In selected ion flow tube mass spectrometry, SIFT-MS, analyses of humid air and breath, it is essential to consider and account for the influence of water vapour in the media, which can be profound for the analysis of some compounds, including H(2)CO, H(2)S and notably CO(2). To date, the analysis of methane has not been considered, since it is known to be unreactive with H(3)O(+) and NO(+), the most important precursor ions for SIFT-MS analyses, and it reacts only slowly with the other available precursor ion, O(2) (+). However, we have now experimentally investigated methane analysis and report that it can be quantified in both air and exhaled breath by exploiting the slow O(2) (+)/CH(4) reaction that produces CH(3)O(2) (+) ions. We show that the ion chemistry is significantly influenced by the presence of water vapour in the sample, which must be quantified if accurate analyses are to be performed. Thus, we have carried out a study of the loss rate of the CH(3)O(2) (+) analytical ion as a function of sample humidity and deduced an appropriate kinetics library entry that provides an accurate analysis of methane in air and breath by SIFT-MS. However, the associated limit of detection is rather high, at 0.2 parts-per-million, ppm. We then measured the methane levels, together with acetone levels, in the exhaled breath of 75 volunteers, all within a period of 3 h, which shows the remarkable sample throughput rate possible with SIFT-MS. The mean methane level in ambient air is seen to be 2 ppm with little spread and that in exhaled breath is 6 ppm, ranging from near-ambient levels to 30 ppm, with no significant variation with age and gender. Methane can now be included in the wide ranging analyses of exhaled breath that are currently being carried out using SIFT-MS.

  4. Aerosols in Polluted versus Nonpolluted Air Masses: Long-Range Transport and Effects on Clouds.

    NASA Astrophysics Data System (ADS)

    Pueschel, R. F.; van Valin, C. C.; Castillo, R. C.; Kadlecek, J. A.; Ganor, E.

    1986-12-01

    To assess the influence of anthropogenic aerosols on the physics and chemistry of clouds in the northeastern United State, aerosol and cloud-drop size distributions, elemental composition of aerosols as a function of size, and ionic content of cloud water were measured on Whiteface Mountain, New York, during the summers of 1981 and 1982. In several case studies, the data were cross-correlated with different air mass types-background continental, polluted continental, and maritime-that were advected to the sampling site. The results are the following (1) Anthropogenic sources hundreds of kilometers upwind cause the small-particle (accumulation) mode number to increase from hundreds to thousands per cubic centimeter and the mass loading to increase from a few to several tens of micrograms per cubic meter, mostly in the form of sulfur aerosols. (ii) A significant fraction of anthropogenic sulfur aerosols appears to act as cloud condensation nuclei (CCN) to affect the cloud drop concentration. (iii) Clouds in Atlantic maritime air masses have cloud drop spectra that are markedly different from those measured in continental clouds. The drop concentration is significantly lower, and the drop size spectra are heavily skewed toward large drops. (iv) Effects of anthropogenic pollutants on cloud water ionic composition are an increase of nitrate by a factor of 50, an increase of sulfate by more than one order of magnitude, and an increase of ammonium ion by a factor of 7. The net effect of the changes in ionic concentrations is an increase in cloud water acidity. An anion deficit even in maritime clouds suggests an unknown, possibly biogenic, source that could be responsible for a pH below neutral, which is frequently observed in nonpolluted clouds.

  5. Finite element analysis of an inflatable torus considering air mass structural element

    NASA Astrophysics Data System (ADS)

    Gajbhiye, S. C.; Upadhyay, S. H.; Harsha, S. P.

    2014-01-01

    Inflatable structures, also known as gossamer structures, are at high boom in the current space technology due to their low mass and compact size comparing to the traditional spacecraft designing. Internal pressure becomes the major source of strength and rigidity, essentially stiffen the structure. However, inflatable space based membrane structure are at high risk to the vibration disturbance due to their low structural stiffness and material damping. Hence, the vibration modes of the structure should be known to a high degree of accuracy in order to provide better control authority. In the past, most of the studies conducted on the vibration analysis of gossamer structures used inaccurate or approximate theories in modeling the internal pressure. The toroidal shaped structure is one of the important key element in space application, helps to support the reflector in space application. This paper discusses the finite-element analysis of an inflated torus. The eigen-frequencies are obtained via three-dimensional small-strain elasticity theory, based on extremum energy principle. The two finite-element model (model-1 and model-2) have cases have been generated using a commercial finite-element package. The structure model-1 with shell element and model-2 with the combination of the mass of enclosed fluid (air) added to the shell elements have been taken for the study. The model-1 is computed with present analytical approach to understand the convergence rate and the accuracy. The convergence study is made available for the symmetric modes and anti-symmetric modes about the centroidal-axis plane, meeting the eigen-frequencies of an inflatable torus with the circular cross section. The structural model-2 is introduced with air mass element and analyzed its eigen-frequency with different aspect ratio and mode shape response using in-plane and out-plane loading condition are studied.

  6. [Influence of atmospheric transport on air pollutant levels at a mountain background site of East China].

    PubMed

    Su, Bin-Bin; Xu, Ju-Yang; Zhang, Ruo-Yu; Ji, Xian-Xin

    2014-08-01

    Transport characteristics of air pollutants transported to the background atmosphere of East China were investigated using HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) 4.8 model driven by NCEP reanalysis data during June 2011 to May 2012. Based on the air pollutants monitoring data collected at the National atmospheric background monitoring station (Wuyishan station) in Fujian Province, characteristics of different clustered air masses as well as the origins of highly polluted air masses were further examined. The results showed that 65% of all the trajectories, in which air masses mainly passed over highly polluted area of East China, Jiangxi province and upper air in desert areas of Northwest China, carried polluted air to the station, while the rest of trajectories (35%) with air masses originated from ocean could effectively remove air pollutants at the Wuyishan station. However, the impact on the air pollutants for each air mass group varied with seasons. Elevated SO2 concentrations observed at the background station were mainly influenced by coal burning activities in Northern China during heating season. The high CO concentrations were likely associated with the pollutants emission in the process of coal production and consumption in Anhui province. The elevated NO(x), O3, PM10 and PM2.5 concentrations were mostly impacted by East China with high levels of air pollutants.

  7. Quantitative back-trajectory apportionment of sources of particulate sulfate at Big Bend National Park, TX

    NASA Astrophysics Data System (ADS)

    Gebhart, Kristi A.; Schichtel, Bret A.; Barna, Michael G.; Malm, William C.

    As part of the Big Bend Regional Aerosol and Visibility Observational (BRAVO) study, a quantitative back-trajectory-based receptor model, Trajectory Mass Balance (TrMB) was used to estimate source apportionment of particulate sulfur measured at Big Bend National Park, Texas, during July-October 1999. The model was exercised using a number of sets of trajectories generated by three different trajectory models, with three different sets of input gridded meteorology, and tracked for 5, 7, and 10 days back in time. The performance of the TrMB model with the different trajectory inputs was first evaluated against perfluorocarbon tracers and synthetically generated sulfate concentrations from a regional air quality model, both of which had known attributions. These tests were used to determine which trajectories were adequate for the TrMB modeling of measured sulfate concentrations, illustrated the magnitude of the daily uncertainties as compared to the uncertainties in the mean attributions, and demonstrated the value of a robust evaluation process. Depending on trajectories, mean sulfate source apportionment results were 39-50% from Mexico, 7-26% from the eastern US, 12-45% from Texas, and 3-25% from the western US. These ranges were inclusive of the best BRAVO attribution estimates for Mexico, Texas, and the western US, but TrMB underestimated the eastern US contribution as compared to the BRAVO best estimates.

  8. An Air Mass Based Approach to the Establishment of Spring Season Synoptic Characteristics in the Northeast United States

    NASA Astrophysics Data System (ADS)

    Zander, R.; Messina, A.; Godek, M. L.

    2012-12-01

    The spring season is indicative of marked meteorological, ecological, and biological changes across the Northeast United States. The onset of spring coincides with distinct meteorological phenomena including an increase in severe weather events and snow meltwaters that can cause localized flooding and other costly damages. Increasing and variable springtime temperatures also influence Northeast tourist operations and agricultural productivity. Even with the vested interest of industry in the season and public awareness of the dynamic characteristics of spring, the definition of spring remains somewhat arbitrary. The primary goal of this research is to obtain a synoptic meteorological definition of the spring season through an assessment of air mass frequency over the past 60 years. A secondary goal examines the validity of recent speculations that the onset and termination of spring has changed in recent decades, particularly since 1975. The Spatial Synoptic Classification is utilized to define daily air masses over the region. Annual and seasonal baseline frequencies are identified and their differences are acquired to characterize the season. Seasonal frequency departures of the early and late segments of the period of record around 1975 are calculated and examined for practical and statistical significance. The daily boundaries of early and late spring are then isolated and frequencies are obtained for these periods. Boundary frequencies are assessed across the period of record to identify important changes in the season's initiation and termination through time. Results indicate that the Northeast spring season is dominated by dry air masses, mainly the Dry Moderate and Dry Polar types. Significant differences in seasonal air mass frequency are also observed through time. Prior to 1975, higher frequencies of polar air mass types are detected while after 1975 there is an increase in the frequencies of both moderate and tropical types. This finding is also

  9. Atmospheric Thickness Variability During Air Mass Conditions and Winter Snow Events at Albany, NY: 2002-2012

    NASA Astrophysics Data System (ADS)

    Dubbs, A. M.; Swift, S.; Godek, M. L.

    2014-12-01

    A winter weather parameter that is underutilized in the prediction of Northeast snowfall events is critical thickness. Knowledge of atmospheric thickness values during snowfall can benefit the accuracy of winter forecasts, especially if thickness layer ranges at times without precipitation are known. This investigation aims to better understand atmospheric thickness variations in the 1000-500, 1000-700, and 1000-850 hPa layers at Albany, New York during snowfall with differing air mass conditions. Since snow can occur alongside a variety of air mass environments, distinctions in layer thickness between air mass types and critical levels will be examined. Pairing air mass information with an improved understanding of thicknesses may allow forecasters to determine normal snowfall conditions of the atmosphere and decipher when anomalous conditions are occurring alongside heavier snows. Daily geopotential height data are examined alongside Spatial Synoptic Classification weather types over the past decade. Air mass frequencies are computed and baseline thicknesses are established for non-snow days, days with snow and liquid precipitation, and days with only snowfall. Thicknesses are compared to those computed for seven air mass types and differences layers are examined for continuity. For the three air masses identified as prevalent during heavy snow, light-to-heavy and early-to-late season snowfall categories are established and thickness variations are evaluated against non-snow days for significant differences. Results indicate that the differences in layer thicknesses are comparable for all precipitation and non-snow days but around 40 geopotential meters less for pure-snow days. For air masses present during snow, layer thicknesses can vary by over 100 gpm with type. Isolating polar varieties, approximately 50 gpm thickness differences are found in pure-snow days. Comparable differences are detected between the moderate and polar types and the continuity between

  10. Orbiter Trajectory Analysis for a Two-Stage Reusable Launch Vehicle

    NASA Technical Reports Server (NTRS)

    Cowling, Adam L.

    2011-01-01

    Trajectory analysis performed on NASA's reference two-stage-to-orbit launch vehicle upper stage will be presented. The work was completed in support of the Hypersonics Multidisciplinary Analysis and Optimization effort for the NASA-Air Force Joint System Study. Three degree-of-freedom (3-DOF) untrimmed trajectory analysis was performed for the orbiter ascent, closure and re-entry. An iterative closure process resulted in a 333,000 lb initial mass for the orbiter. The re-entry trajectory satisfied heating constraints for all payload out cases and met the constraints with reduced margins for payload in cases. Abort trajectories for engine out at staging, engine out during ascent, and failure to circularize in orbit, gave insight to the robustness of the orbiter. A trimmed ascent trajectory defined an engine gimbal location and the body flap angle best suited for maximizing injected mass. A trimmed re-entry trajectory revealed a need to update the trim routine to accommodate full flap aerodynamic data.

  11. Composition of air masses in Fuerteventura (Canary Islands) according to their origins

    SciTech Connect

    Patier, R.F.; Diez Hernandez, P.; Diaz Ramiro, E.; Ballesteros, J.S.; Santos-Alves, S.G. dos

    1994-12-31

    The Centro Nacional de Sanidad Ambiental has among their duties the background atmospheric pollution monitoring in Spain. To do so, the laboratory has set up 6 field stations in the Iberian Peninsula. In these stations, both gaseous and particulate pollutants are currently analyzed. However, there is a lack of data about the atmospheric pollution in the Canary, where they are a very strong influence of natural emissions from sea and the Saharan desert, mixed with anthropogenic ones. Therefore, during the ASTEX/MAGE project the CNSA established a station in Fuerteventura island, characterized by the nonexistence of man-made emissions, to measure some atmospheric pollutants, in order to foresee their origins. In this study, the authors analyzed some pollutants that are used to obtain a clue about the sources of air masses such as gaseous ozone and metallic compounds (vanadium, iron and manganese) in the atmospheric aerosol fractionated by size.

  12. Operational performance of a low cost, air mass 2 solar simulator

    NASA Technical Reports Server (NTRS)

    Yass, K.; Curtis, H. B.

    1975-01-01

    Modifications and improvements on a low cost air mass 2 solar simulator are discussed. The performance characteristics of total irradiance, uniformity of irradiance, spectral distribution, and beam subtense angle are presented. The simulator consists of an array of tungsten halogen lamps hexagonally spaced in a plane. A corresponding array of plastic Fresnel lenses shapes the output beam such that the simulator irradiates a 1.2 m by 1.2 m area with uniform collimated irradiance. Details are given concerning individual lamp output measurements and placement of the lamps. Originally, only the direct component of solar irradiance was simulated. Since the diffuse component may affect the performance of some collectors, the capability to simulate it is being added. An approach to this diffuse addition is discussed.

  13. Progress Toward a Global, EOS-Era Aerosol Air Mass Type Climatology

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.

    2012-01-01

    The MISR and MODIS instruments aboard the NASA Earth Observing System's Terra Satellite have been collecting data containing information about the state of Earth's atmosphere and surface for over eleven years. Data from these instruments have been used to develop a global, monthly climatology of aerosol amount that is widely used as a constraint on climate models, including those used for the 2007 IPCC assessment report. The next frontier in assessing aerosol radiative forcing of climate is aerosol type, and in particular, the absorption properties of major aerosol air masses. This presentation will focus on the prospects for constraining aerosol type globally, and the steps we are taking to apply a combination of satellite and suborbital data to this challenge.

  14. Simultaneous measurement of mass and rotation of trapped absorbing particles in air.

    PubMed

    Bera, Sudipta K; Kumar, Avinash; Sil, Souvik; Saha, Tushar Kanti; Saha, Tanumoy; Banerjee, Ayan

    2016-09-15

    We trap absorbing micro-particles in air by photophoretic forces generated using a single loosely focused Gaussian trapping beam. We measure a component of the radial Brownian motion of a trapped particle cluster and determine the power spectral density, mean squared displacement, and normalized position and velocity autocorrelation functions to characterize the photophoretic body force in a quantitative fashion for the first time. The trapped particles also undergo spontaneous rotation due to the action of this force. This is evident from the spectral density that displays clear peaks at the rotation and the particles' inertial resonance frequencies. We fit the spectral density to the well-known analytical function derived from the Langevin equation, measure the resonance and rotation frequencies, and determine the values for particle mass that we verify at different trapping laser powers with reasonable accuracy. PMID:27628396

  15. AUTOMATED DECONVOLUTION OF COMPOSITE MASS SPECTRA OBTAINED WITH AN OPEN-AIR IONIZATIONS SOURCE BASED ON EXACT MASSES AND RELATIVE ISOTIPIC ABUNDANCES

    EPA Science Inventory

    Chemicals dispersed by accidental, deliberate, or weather-related events must be rapidly identified to assess health risks. Mass spectra from high levels of analytes obtained using rapid, open-air ionization by a Direct Analysis in Real Time (DART®) ion source often contain

  16. Design and Analysis of Optimal Ascent Trajectories for Stratospheric Airships

    NASA Astrophysics Data System (ADS)

    Mueller, Joseph Bernard

    Stratospheric airships are lighter-than-air vehicles that have the potential to provide a long-duration airborne presence at altitudes of 18-22 km. Designed to operate on solar power in the calm portion of the lower stratosphere and above all regulated air traffic and cloud cover, these vehicles represent an emerging platform that resides between conventional aircraft and satellites. A particular challenge for airship operation is the planning of ascent trajectories, as the slow moving vehicle must traverse the high wind region of the jet stream. Due to large changes in wind speed and direction across altitude and the susceptibility of airship motion to wind, the trajectory must be carefully planned, preferably optimized, in order to ensure that the desired station be reached within acceptable performance bounds of flight time and energy consumption. This thesis develops optimal ascent trajectories for stratospheric airships, examines the structure and sensitivity of these solutions, and presents a strategy for onboard guidance. Optimal ascent trajectories are developed that utilize wind energy to achieve minimum-time and minimum-energy flights. The airship is represented by a three-dimensional point mass model, and the equations of motion include aerodynamic lift and drag, vectored thrust, added mass effects, and accelerations due to mass flow rate, wind rates, and Earth rotation. A representative wind profile is developed based on historical meteorological data and measurements. Trajectory optimization is performed by first defining an optimal control problem with both terminal and path constraints, then using direct transcription to develop an approximate nonlinear parameter optimization problem of finite dimension. Optimal ascent trajectories are determined using SNOPT for a variety of upwind, downwind, and crosswind launch locations. Results of extensive optimization solutions illustrate definitive patterns in the ascent path for minimum time flights across

  17. Bioaccumulation Potential Of Air Contaminants: Combining Biological Allometry, Chemical Equilibrium And Mass-Balances To Predict Accumulation Of Air Pollutants In Various Mammals

    SciTech Connect

    Veltman, Karin; McKone, Thomas E.; Huijbregts, Mark A.J.; Hendriks, A. Jan

    2009-03-01

    In the present study we develop and test a uniform model intended for single compartment analysis in the context of human and environmental risk assessment of airborne contaminants. The new aspects of the model are the integration of biological allometry with fugacity-based mass-balance theory to describe exchange of contaminants with air. The developed model is applicable to various mammalian species and a range of chemicals, while requiring few and typically well-known input parameters, such as the adult mass and composition of the species, and the octanol-water and air-water partition coefficient of the chemical. Accumulation of organic chemicals is typically considered to be a function of the chemical affinity forlipid components in tissues. Here, we use a generic description of chemical affinity for neutral and polar lipids and proteins to estimate blood-air partition coefficients (Kba) and tissue-air partition coefficients (Kta) for various mammals. This provides a more accurate prediction of blood-air partition coefficients, as proteins make up a large fraction of total blood components. The results show that 75percent of the modeled inhalation and exhalation rate constants are within a factor of 2 from independent empirical values for humans, rats and mice, and 87percent of the predicted blood-air partition coefficients are within a factor of 5 from empirical data. At steady-state, the bioaccumulation potential of air pollutants is shown to be mainly a function of the tissue-air partition coefficient and the biotransformation capacity of the species and depends weakly on the ventilation rate and the cardiac output of mammals.

  18. Ring waves as a mass transport mechanism in air-driven core-annular flows.

    PubMed

    Camassa, Roberto; Forest, M Gregory; Lee, Long; Ogrosky, H Reed; Olander, Jeffrey

    2012-12-01

    Air-driven core-annular fluid flows occur in many situations, from lung airways to engineering applications. Here we study, experimentally and theoretically, flows where a viscous liquid film lining the inside of a tube is forced upwards against gravity by turbulent airflow up the center of the tube. We present results on the thickness and mean speed of the film and properties of the interfacial waves that develop from an instability of the air-liquid interface. We derive a long-wave asymptotic model and compare properties of its solutions with those of the experiments. Traveling wave solutions of this long-wave model exhibit evidence of different mass transport regimes: Past a certain threshold, sufficiently large-amplitude waves begin to trap cores of fluid which propagate upward at wave speeds. This theoretical result is then confirmed by a second set of experiments that show evidence of ring waves of annular fluid propagating over the underlying creeping flow. By tuning the parameters of the experiments, the strength of this phenomenon can be adjusted in a way that is predicted qualitatively by the model.

  19. Body mass penalties in the physical fitness tests of the Army, Air Force, and Navy.

    PubMed

    Vanderburgh, Paul M; Crowder, Todd A

    2006-08-01

    Recent research has empirically documented a consistent penalty against heavier service members for events identical or similar to those in the physical fitness tests of the Army, Air Force, and Navy. These penalties, which are not related to body fatness, are based on biological scaling models and have a physiological basis. Using hypothetical cases, we quantified the penalties for men, with body mass of 60 vs. 90 kg, and women, 45 vs. 75 kg, to be 15% to 20% for the fitness tests of these three services. Such penalties alone can adversely affect awards and promotions for heavier service members. To deal equitably with these penalties in a practical manner, we offer two recommendations, i.e., (1) implementation of revised fitness tests with balanced events, in which the penalties of one event for heavier service members are balanced by an equal and opposite bias against lighter service members, or (2) development of correction factors that can be multiplied by raw scores to yield adjusted scores free of body mass bias.

  20. Characteristics of tyre dust in polluted air: Studies by single particle mass spectrometry (ATOFMS)

    NASA Astrophysics Data System (ADS)

    Dall'Osto, Manuel; Beddows, David C. S.; Gietl, Johanna K.; Olatunbosun, Oluremi A.; Yang, Xiaoguang; Harrison, Roy M.

    2014-09-01

    There is a paucity of quantitative knowledge on the contributions of non-exhaust (abrasion and re-suspension) sources to traffic emissions. Abrasive emissions can be broadly categorised as tyre wear, brake wear and road dust/road surface wear. Current research often considers road dust and tyre dust as externally mixed particles, the former mainly composed of mineral matter and the latter solely composed of mainly organic matter and some trace elements. The aim of this work was to characterise tyre wear from both laboratory and field studies by using Aerosol Time-Of-Flight Mass Spectrometry (ATOFMS). Real-time single particle chemical composition was obtained from a set of rubber tyres rotating on a metal surface. Bimodal particle number size distributions peaking at 35 nm and 85 nm were obtained from SMPS/APS measurements over the range 6-20,000 nm. ATOFMS mass spectra of tyre wear in the particle size range 200-3000 nm diameter show peaks due to exo-sulphur compounds, nitrate, Zn and ions of high molecular weight (m/z > 100) attributed to organic polymers. Two large ATOFMS datasets collected from a number of outdoor studies were examined. The former was constituted of 48 road dust samples collected on the roads of London. The latter consisted of ATOFMS ambient air field studies from Europe, overall composed of more than 2,000,000 single particle mass spectra. The majority (95%) of tyre wear particles present in the road dust samples and atmospheric samples are internally mixed with metals (Li, Na, Ca, Fe, Ti), as well as phosphate. It is concluded that the interaction of tyres with the road surface creates particles internally mixed from two sources: tyre rubber and road surface materials. Measurements of the tyre rubber component alone may underestimate the contribution of tyre wear to concentrations of airborne particulate matter. The results presented are especially relevant for urban aerosol source apportionment and PM2.5 exposure assessment.

  1. Study Case of Air-Mass Modification over Poland and Romania Observed by the Means of Multiwavelength Raman Depolarization Lidars

    NASA Astrophysics Data System (ADS)

    Costa-Surós, Montserrat; Janicka, Lucja; Stachlewska, Iwona S.; Nemuc, Anca; Talianu, Camelia; Heese, Birgit; Engelmann, Ronny

    2016-06-01

    An air-mass modification, on its way from Poland to Romania, observed between 19-21 July 2014 is discussed. The air-mass was investigated using data of two multi-wavelength lidars capable of performing regular elastic, depolarization and Raman measurements in Warsaw, Poland, and in Magurele, Romania. The analysis was focused on evaluating optical properties of aerosol in order to search for similarities and differences in the vertical profiles describing the atmospheric layers above the two stations within given period.

  2. Numerical Calculation of Model Rocket Trajectories.

    ERIC Educational Resources Information Center

    Keeports, David

    1990-01-01

    Discussed is the use of model rocketry to teach the principles of Newtonian mechanics. Included are forces involved; calculations for vertical launches; two-dimensional trajectories; and variations in mass, drag, and launch angle. (CW)

  3. Mars Ascent Propulsion Trades with Trajectory Analysis

    SciTech Connect

    Whitehead, J

    2004-04-22

    Optimized trajectories to a 500 km circular orbit are calculated for vehicles having a 100 kg Mars launch mass. Staging trades, thrust optimization, and the importance of vehicle shape for drag are all taken into consideration. The high acceleration of solid rockets requires a steep trajectory for drag avoidance, followed by a relatively large circularization burn, appropriate for a second stage. Liquid thrust reduces drag, resulting in less steep trajectories which have small circularization burns. Liquid propulsion requires less total {Delta}v, and offers options for multiple stages or just one. Graphs of payload mass versus stage propellant fractions are compared for liquid and solid propulsion.

  4. On the association between daily mortality and air mass types in Athens, Greece during winter and summer

    NASA Astrophysics Data System (ADS)

    Kassomenos, Pavlos A.; Gryparis, Alexandros; Katsouyanni, Klea

    2007-03-01

    In this study, we examined the short-term effects of air mass types on mortality in Athens, Greece. An objective air mass types classification was used, based on meteorological parameters measured at the surface. Mortality data were treated with generalized additive models (GAM) and extending Poisson regression, using a LOESS smoother to control for the confounding effects of seasonal patterns, adjusting also for temperature, long-term trends, day of the week, and ambient particle concentrations. The introduced air mass classification explains the daily variation of mortality to a statistically significant degree. The highest daily mortality was observed on days characterized by southerly flow conditions for both the cold (increase in relative risk for mortality 9%; with a 95% confidence interval: 3-14%), and the warm period (7%; with a 95% confidence interval: 2-13%) of the year. The northeasterly flow is associated with the lowest mortality. Effects on mortality, independent of temperature, are observed mainly for lag 0 during the cold period, but persist longer during the warm period. Not adjusting for temperature and/or ambient particle levels slightly alters the results, which then reflect the known temperature and particle effects, already reported in the literature. In conclusion, we find that air mass types have independent effects on mortality for both the cold and warm season and may be used to predict weather-related adverse health effects.

  5. A Longitudinal Cohort Study of Body Mass Index and Childhood Exposure to Secondhand Tobacco Smoke and Air Pollution: The Southern California Children’s Health Study

    PubMed Central

    Shen, Ernest; Gilliland, Frank D.; Jerrett, Michael; Wolch, Jennifer; Chang, Chih-Chieh; Lurmann, Frederick; Berhane, Kiros

    2014-01-01

    Background: Childhood body mass index (BMI) and obesity prevalence have been associated with exposure to secondhand smoke (SHS), maternal smoking during pregnancy, and vehicular air pollution. There has been little previous study of joint BMI effects of air pollution and tobacco smoke exposure. Methods: Information on exposure to SHS and maternal smoking during pregnancy was collected on 3,318 participants at enrollment into the Southern California Children’s Health Study. At study entry at average age of 10 years, residential near-roadway pollution exposure (NRP) was estimated based on a line source dispersion model accounting for traffic volume, proximity, and meteorology. Lifetime exposure to tobacco smoke was assessed by parent questionnaire. Associations with subsequent BMI growth trajectory based on annual measurements and attained BMI at 18 years of age were assessed using a multilevel modeling strategy. Results: Maternal smoking during pregnancy was associated with estimated BMI growth over 8-year follow-up (0.72 kg/m2 higher; 95% CI: 0.14, 1.31) and attained BMI (1.14 kg/m2 higher; 95% CI: 0.66, 1.62). SHS exposure before enrollment was positively associated with BMI growth (0.81 kg/m2 higher; 95% CI: 0.36, 1.27) and attained BMI (1.23 kg/m2 higher; 95% CI: 0.86, 1.61). Growth and attained BMI increased with more smokers in the home. Compared with children without a history of SHS and NRP below the median, attained BMI was 0.80 kg/m2 higher (95% CI: 0.27, 1.32) with exposure to high NRP without SHS; 0.85 kg/m2 higher (95% CI: 0.43, 1.28) with low NRP and a history of SHS; and 2.15 kg/m2 higher (95% CI: 1.52, 2.77) with high NRP and a history of SHS (interaction p-value 0.007). These results suggest a synergistic effect. Conclusions: Our findings strengthen emerging evidence that exposure to tobacco smoke and NRP contribute to development of childhood obesity and suggest that combined exposures may have synergistic effects. Citation: McConnell R, Shen E

  6. Caucasian children's fat mass: routine anthropometry v. air-displacement plethysmography.

    PubMed

    Michels, Nathalie; Huybrechts, Inge; Bammann, Karin; Lissner, Lauren; Moreno, Luis; Peeters, Maarten; Sioen, Isabelle; Vanaelst, Barbara; Vyncke, Krishna; De Henauw, Stefaan

    2013-04-28

    The present paper will use fat mass percentage (FM%) obtained via BOD POD® air-displacement plethysmography (FMADP%) to examine the relative validity of (1) anthropometric measurements/indices and (2) of FM% assessed with equations (FMeq%) based on skinfold thickness and bioelectrical impedance (BIA). In 480 Belgian children (aged 5-11 years) weight, height, skinfold thickness (triceps and subscapular), body circumferences (mid-upper arm, waist and hip), foot-to-foot BIA (Tanita®) and FMADP% were measured. Anthropometric measurements and calculated indices were compared with FMADP%. Next, published equations were used to calculate FMeq% using impedance (equations of Tanita®, Tyrrell, Shaefer and Deurenberg) or skinfold thickness (equations of Slaughter, Goran, Dezenberg and Deurenberg). Both indices and equations performed better in girls than in boys. For both sexes, the sum of skinfold thicknesses resulted in the highest correlation with FMADP%, followed by triceps skinfold, arm fat area and subscapular skinfold. In general, comparing FMeq% with FMADP% indicated mostly an age and sex effect, and an increasing underestimation but less dispersion with increasing FM%. The Tanita® impedance equation and the Deurenberg skinfold equation performed the best, although none of the used equations were interchangeable with FMADP%. In conclusion, the sum of triceps and subscapular skinfold thickness is recommended as marker of FM% in the absence of specialised technologies. Nevertheless, the higher workload, cost and survey management of an immobile device like the BOD POD® remains justified.

  7. New Directions: Questions surrounding suspended particle mass used as a surrogate for air quality and for regulatory control of ambient urban air pollution

    NASA Astrophysics Data System (ADS)

    Hoare, John L.

    2014-07-01

    The original choice of particulate matter mass (PM) as a realistic surrogate for gross air pollution has gradually evolved into routine use nowadays of epidemiologically-based estimates of the monetary and other benefits expected from regulating urban air quality. Unfortunately, the statistical associations facilitating such calculations usually are based on single indices of air pollution whereas the health effects themselves are more broadly based causally. For this and other reasons the economic benefits of control tend to be exaggerated. Primarily because of their assumed inherently inferior respirability, particles ≥10 μm are generally excluded from such considerations. Where the particles themselves are chemically heterogeneous, as in an urban context, this may be inappropriate. Clearly all air-borne particles, whether coarse or fine, are susceptible to inhalation. Hence, the possibility exists for any adhering potentially harmful semi-volatile substances to be subsequently de-sorbed in vivo thereby facilitating their transport deeper into the lungs. Consequently, this alone may be a sufficient reason for including rather than rejecting during air quality monitoring the relatively coarse 10-100 μm particle fraction, ideally in conjunction with routine estimation of the gaseous co-pollutants thereby facilitating a multi-pollutant approach apropos regulation.

  8. Variations of the glacio-marine air mass front in West Greenland through water vapor isotopes

    NASA Astrophysics Data System (ADS)

    Kopec, B. G.; Lauder, A. M.; Posmentier, E. S.; Feng, X.

    2012-12-01

    While the isotopic distribution of precipitation has been widely used for research in hydrology, paleoclimatology, and ecology for decades, intensive isotopic studies of atmospheric water vapor has only recently been made possible by spectral-based technology. New instrumentation based on this technology opens up many opportunities to investigate short-term atmospheric dynamics involving the water cycle and moisture transport. We deployed a Los Gatos Water Vapor Isotope Analyzer (WVIA) at Kangerlussuaq, Greenland from July 21 to August 15, and measured the water vapor concentration and its isotopic ratios continuously at 10s intervals. A Danish Meteorological Institute site is located about 1 km from the site of the deployment, and meteorological data is collected at 30 min intervals. During the observation period, the vapor concentration of the ambient air ranges from 5608.4 to 11189.4 ppm; dD and d18O range from -254.5 to -177.7 ‰ and -34.2 to -23.2 ‰, respectively. The vapor content (dew point) and the isotopic ratios are both strongly controlled by the wind direction. The easterly winds are associated with dry, isotopically depleted air masses formed over the glacier, while westerly winds are associated with moist and isotopically enriched air masses from the marine/fjord surface. This region typically experiences katabatic winds off of the ice sheet to the east. However, during some afternoons, the wind shifts 180 degrees, blowing off the fjord to the west. This wind switch marks the onset of a sea breeze, and significant isotopic enrichment results. Enrichment in deuterium is up to 60 ‰ with a mean of 15‰, and oxygen-18 is enriched by 3‰ on average and up to 8 ‰. Other afternoons have no change in wind, and only small changes in humidity and vapor isotopic ratios. The humidity and isotopic variations suggest the local atmosphere circulation is dominated by relatively high-pressure systems above the cold glaciers and cool sea surface, and diurnal

  9. The impact of mass flow and masking on the pressure drop of air filter in heavy-duty diesel engine

    NASA Astrophysics Data System (ADS)

    Hoseeinzadeh, Sepideh; Gorji-Bandpy, Mofid

    2012-04-01

    This paper presents a computational fluid dynamics (CFD) calculation approach to predict and evaluate the impact of the mass-flow inlet on the pressure drop of turbocharger`s air filtfer in heavy-duty diesel engine. The numerical computations were carried out using a commercial CFD program whereas the inlet area of the air filter consisted of several holes connected to a channel. After entering through the channel, the air passes among the holes and enters the air filter. The effect of masking holes and hydraulic diameter is studied and investigated on pressure drop. The results indicate that pressure drop increase with decreasing of hydraulic diameter and masking of the holes has considerable affect on the pressure drop.

  10. Analyzing Shuttle Orbiter Trajectories

    NASA Technical Reports Server (NTRS)

    Lear, W. M.

    1986-01-01

    LRBET4 program best-estimated-of-trajectory (BET) calculation for post-flight trajectory analysis of Shuttle orbiter. Produces estimated measurements for comparing predicted and actual trajectory of Earth-orbiting spacecraft. Kalman filter and smoothing filter applied to input data to estimate state vector, reduce noise, and produce BET. LRBET4 written in FORTRAN IV for batch execution.

  11. Chiral Signatures of Anthropogenic Semi-Volatile Organic Compounds in Asian, trans- Pacific, and Pacific Northwestern Air Masses

    NASA Astrophysics Data System (ADS)

    Genualdi, S.; Primbs, T.; Bidleman, T.; Jantunen, L.; Simonich, S.

    2006-12-01

    The goal of this research is to use the chiral signatures of Semi-Volatile Organic Compounds (SOCs) to distinguish between new and old sources in Asian, trans-Pacific, and regional air masses. During 2004, a six week air sampling campaign was conducted at a remote site in Okinawa, Japan to determine the chemical composition of Eurasian air masses. During 2003 and 2004, high volume air samples were collected at three different locations in the Pacific Northwest of the United States. These sampling locations were; Mary's Peak Observatory (MPO) located at 1250m in the Oregon Coast Range, Mt. Bachelor located at 2800m in Oregon's Cascade Range, and Cheeka Peak Observatory (CPO) located at 500m in the state of Washington. The air samples consisted of both polyurethane foam and XAD-2 resin to collect the gas phase SOCs, and glass fiber filters to collect the particulate phase SOCs. The samples were extracted using accelerated solvent extraction and enantiomer fractions were determined using GCMS-ECNI with the use of a BGB Analytik chiral column. The chiral SOCs, á-Hexachlorocyclohexane, cis and trans chlordane, heptachlor epoxide, and o'p' DDT, were measured, the enantiomer ratios were determined, and potential new and historical sources of these compounds were identified.

  12. Ozone-surface interactions: Investigations of mechanisms, kinetics, mass transport, and implications for indoor air quality

    SciTech Connect

    Morrison, Glenn C.

    1999-12-01

    {sup {minus}7}, 10{sup {minus}5}, and 10{sup {minus}5} respectively. To understand how internal surface area influences the equivalent reaction probability of whole carpet, a model of ozone diffusion into and reaction with internal carpet components was developed. This was then used to predict apparent reaction probabilities for carpet. He combines this with a modified model of turbulent mass transfer developed by Liu, et al. to predict deposition rates and indoor ozone concentrations. The model predicts that carpet should have an equivalent reaction probability of about 10{sup {minus}5}, matching laboratory measurements of the reaction probability. For both carpet and duct materials, surfaces become progressively quenched (aging), losing the ability to react or otherwise take up ozone. He evaluated the functional form of aging and find that the reaction probability follows a power function with respect to the cumulative uptake of ozone. To understand ozone aging of surfaces, he developed several mathematical descriptions of aging based on two different mechanisms. The observed functional form of aging is mimicked by a model which describes ozone diffusion with internal reaction in a solid. He shows that the fleecy nature of carpet materials in combination with the model of ozone diffusion below a fiber surface and internal reaction may explain the functional form and the magnitude of power function parameters observed due to ozone interactions with carpet. The ozone induced aldehyde emissions, measured from duct materials, were combined with an indoor air quality model to show that concentrations of aldehydes indoors may approach odorous levels. He shows that ducts are unlikely to be a significant sink for ozone due to the low reaction probability in combination with the short residence time of air in ducts.

  13. Overview of aerosol properties associated with air masses sampled by the ATR-42 during the EUCAARI campaign (2008)

    NASA Astrophysics Data System (ADS)

    Crumeyrolle, S.; Schwarzenboeck, A.; Roger, J. C.; Sellegri, K.; Burkhart, J. F.; Stohl, A.; Gomes, L.; Quennehen, B.; Roberts, G.; Weigel, R.; Villani, P.; Pichon, J. M.; Bourrianne, T.; Laj, P.

    2013-05-01

    Within the frame of the European Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) project, the Météo-France aircraft ATR-42 performed 22 research flights over central Europe and the North Sea during the intensive observation period in May 2008. For the campaign, the ATR-42 was equipped to study the aerosol physical, chemical, hygroscopic and optical properties, as well as cloud microphysics. For the 22 research flights, retroplume analyses along the flight tracks were performed with FLEXPART in order to classify air masses into five sectors of origin, allowing for a qualitative evaluation of emission influence on the respective air parcel. This study shows that the extensive aerosol parameters (aerosol mass and number concentrations) show vertical decreasing gradients and in some air masses maximum mass concentrations (mainly organics) in an intermediate layer (1-3 km). The observed mass concentrations (in the boundary layer (BL): between 10 and 30 μg m-3; lower free troposphere (LFT): 0.8 and 14 μg m-3) are high especially in comparison with the 2015 European norms for PM2.5 (25 μg m-3) and with previous airborne studies performed over England (Morgan et al., 2009; McMeeking et al., 2012). Particle number size distributions show a larger fraction of particles in the accumulation size range in the LFT compared to BL. The chemical composition of submicron aerosol particles is dominated by organics in the BL, while ammonium sulphate dominates the submicron aerosols in the LFT, especially in the aerosol particles originated from north-eastern Europe (~ 80%), also experiencing nucleation events along the transport. As a consequence, first the particle CCN acting ability, shown by the CCN/CN ratio, and second the average values of the scattering cross sections of optically active particles (i.e. scattering coefficient divided by the optical active particle concentration) are increased in the LFT compared to BL.

  14. Influence of the ozone profile above Madrid (Spain) on Brewer estimation of ozone air mass factor

    NASA Astrophysics Data System (ADS)

    Antón, M.; López, M.; Costa, M. J.; Serrano, A.; Bortoli, D.; Bañón, M.; Vilaplana, J. M.; Silva, A. M.

    2009-08-01

    The methodology used by Brewer spectroradiometers to estimate the ozone column is based on differential absorption spectroscopy. This methodology employs the ozone air mass factor (AMF) to derive the total ozone column from the slant path ozone amount. For the calculating the ozone AMF, the Brewer algorithm assumes that the ozone layer is located at a fixed height of 22 km. However, for a real specific site the ozone presents a certain profile, which varies spatially and temporally depending on the latitude, altitude and dynamical conditions of the atmosphere above the site of measurements. In this sense, this work address the reliability of the mentioned assumption and analyses the influence of the ozone profiles measured above Madrid (Spain) in the ozone AMF calculations. The approximated ozone AMF used by the Brewer algorithm is compared with simulations obtained using the libRadtran radiative transfer model code. The results show an excellent agreement between the simulated and the approximated AMF values for solar zenith angle lower than 75°. In addition, the relative differences remain lower than 2% at 85°. These good results are mainly due to the fact that the altitude of the ozone layer assumed constant by the Brewer algorithm for all latitudes notably can be considered representative of the real profile of ozone above Madrid (average value of 21.7±1.8 km). The operational ozone AMF calculations for Brewer instruments are limited, in general, to SZA below 80°. Extending the usable SZA range is especially relevant for Brewer instruments located at high mid-latitudes.

  15. Determination of benzene, toluene, ethylbenzene and xylenes in air by solid phase micro-extraction/gas chromatography/mass spectrometry.

    PubMed

    Tumbiolo, Simonetta; Gal, Jean-François; Maria, Pierre-Charles; Zerbinati, Orfeo

    2004-11-01

    The aim of the study was to analyse BTEX compounds (benzene, toluene, ethylbenzene, xylenes) in air by solid phase micro-extraction/gas chromatography/mass spectrometry (SPME/GC/MS), and this article presents the features of the calibration method proposed. Examples of real-world air analysis are given. Standard gaseous mixtures of BTEX in air were generated by dynamic dilution. SPME sampling was carried out under non-equilibrium conditions using a Carboxen/PDMS fibre exposed for 30 min to standard gas mixtures or to ambient air. The behaviour of the analytical response was studied from 0 to 65 microg/m3 by adding increasing amounts of BTEX to the air matrix. Detection limits range from 0.05 to 0.1 microg/m3 for benzene, depending on the fibre. Inter-fibre relative standard deviations (reproducibility) are larger than 18%, although the repeatability for an individual fibre is better than 10%. Therefore, each fibre should be considered to be a particular sampling device, and characterised individually depending on the required accuracy. Sampling indoor and outdoor air by SPME appears to be a suitable short-delay diagnostic method for volatile organic compounds, taking advantage of short sampling time and simplicity.

  16. An automated gas chromatography time-of-flight mass spectrometry instrument for the quantitative analysis of halocarbons in air

    NASA Astrophysics Data System (ADS)

    Obersteiner, F.; Bönisch, H.; Engel, A.

    2015-09-01

    We present the characterization and application of a new gas chromatography-time-of-flight mass spectrometry instrument (GC-TOFMS) for the quantitative analysis of halocarbons in air samples. The setup comprises three fundamental enhancements compared to our earlier work (Hoker et al., 2015): (1) full automation, (2) a mass resolving power R = m/Δ m of the TOFMS (Tofwerk AG, Switzerland) increased up to 4000 Th/Th and (3) a fully accessible data format of the mass spectrometric data. Automation in combination with the accessible data allowed an in-depth characterization of the instrument. Mass accuracy was found around 5 ppm after automatic recalibration of the mass axis in each measurement. A TOFMS configuration giving R = 3500 was chosen to provide an R-to-sensitivity ratio suitable for our purpose. Calculated detection limits were as low as a few femtograms as mass traces could be made highly specific for selected molecule fragments with the accurate mass information. The precision for substance quantification was 0.15 % at the best for an individual measurement and in general mainly determined by the signal-to-noise ratio of the chromatographic peak. The TOFMS was found to be linear within a concentration range from about 1 pg to 1 ng of analyte per Liter of air. At higher concentrations, non-linearities of a few percent were observed (precision level: 0.2 %) but could be attributed to a potential source within the detection system. A straight-forward correction for those non-linearities was applied in data processing, again by exploiting the accurate mass information. Based on the overall characterization results, the GC-TOFMS instrument was found to be very well-suited for the task of quantitative halocarbon trace gas observation and a big step forward compared to scanning, low resolution quadrupole MS and a TOFMS technique reported to be non-linear and restricted by a small dynamical range.

  17. Interdecadal linkages between Pacific decadal oscillation and interhemispheric air mass oscillation and their possible connections with East Asian Monsoon

    NASA Astrophysics Data System (ADS)

    Lu, C.

    2015-12-01

    The Pacific decadal oscillation (PDO) recently emerged in the literature as a robust signal in the Northern Hemisphere climate variability. Many studies reported that the relationships between PDO and East Asian monsoon (EAM) and climate variability in China are significant. However, the possible mechanisms are still unclear. The present study investigates the interdecadal relationship between Pacific decadal oscillation (PDO) and interhemispheric air mass imbalance or oscillation (IHO) between the Northern and Southern Hemispheres. The possible connection of PDO and IHO with both East Asian monsoon and climate variability in China are also assessed in this study. It is found that the interdecadal components (11-38 years) of PDO, IHO, and EAM contribute large variance to low frequency variations, and they are well-matched with each other on (inter)decadal timescale. In particular, their negative phases mainly appeared in the 1970s and late 1990s, while positive phase in period from 1980s to mid 1990s. Decadal change of global mean air columnar temperature may be the key factor for the notable difference between PDO and IHO from mid 1970s to mid 1990s. The spatial distributions of PDO and IHO associated surface air temperature and surface pressure anomalies exhibit highly similar and large scale characteristics, indicative of their intimate linkage with air mass redistribution over global domain especially over 300S-500N. The PDO associated columnar integral of velocity potential anomalies that maintain the air mass redistribution, show a dipole pattern with air mass flux emanating mainly from the eastern hemisphere to the Pacific regions in positive PDO phase. This contributes to hemispherical and land-sea mass exchange and redistribution, and also leads to the decadal displacement of both upward and downward branch of Walker circulation. In positive phase of PDO, an anomalous anticyclone is found in the Mongolian region in both boreal summer and winter seasons

  18. Influence of power ultrasound application on mass transport and microstructure of orange peel during hot air drying

    NASA Astrophysics Data System (ADS)

    Ortuño, Carmen; Pérez-Munuera, Isabel; Puig, Ana; Riera, Enrique; Garcia-Perez, J. V.

    2010-01-01

    Power ultrasound application on convective drying of foodstuffs may be considered an emergent technology. This work deals with the influence of power ultrasound on drying of natural materials addressing the kinetic as well as the product's microstructure. Convective drying kinetics of orange peel slabs (thickness 5.95±0.41 mm) were carried out at 40 ∘C and 1 m/s with (US) and without (AIR) power ultrasound application. A diffusion model considering external resistance to mass transfer was considered to describe drying kinetics. Fresh, US and AIR dried samples were analyzed using Cryo-SEM. Results showed that drying kinetics of orange peel were significantly improved by the application of power ultrasound. From modeling, it was observed a significant (p¡0.05) increase in both mass transfer coefficient and effective moisture diffusivity. The effects on mass transfer properties were confirmed from microestructural observations. In the cuticle surface, the pores were obstructed by wax components scattering, which evidence the ultrasonic effects on the interfaces. The cells of the flavedo were compressed and large intercellular air spaces were generated in the albedo facilitating water transfer through it.

  19. Trajectory analysis and optimization system (TAOS) user`s manual

    SciTech Connect

    Salguero, D.E.

    1995-12-01

    The Trajectory Analysis and Optimization System (TAOS) is software that simulates point--mass trajectories for multiple vehicles. It expands upon the capabilities of the Trajectory Simulation and Analysis program (TAP) developed previously at Sandia National Laboratories. TAOS is designed to be a comprehensive analysis tool capable of analyzing nearly any type of three degree-of-freedom, point-mass trajectory. Trajectories are broken into segments, and within each segment, guidance rules provided by the user control how the trajectory is computed. Parametric optimization provides a powerful method for satisfying mission-planning constraints. Althrough TAOS is not interactive, its input and output files have been designed for ease of use. When compared to TAP, the capability to analyze trajectories for more than one vehicle is the primary enhancement, although numerous other small improvements have been made. This report documents the methods used in TAOS as well as the input and output file formats.

  20. Trajectories of Martian Habitability

    PubMed Central

    2014-01-01

    Abstract Beginning from two plausible starting points—an uninhabited or inhabited Mars—this paper discusses the possible trajectories of martian habitability over time. On an uninhabited Mars, the trajectories follow paths determined by the abundance of uninhabitable environments and uninhabited habitats. On an inhabited Mars, the addition of a third environment type, inhabited habitats, results in other trajectories, including ones where the planet remains inhabited today or others where planetary-scale life extinction occurs. By identifying different trajectories of habitability, corresponding hypotheses can be described that allow for the various trajectories to be disentangled and ultimately a determination of which trajectory Mars has taken and the changing relative abundance of its constituent environments. Key Words: Mars—Habitability—Liquid water—Planetary science. Astrobiology 14, 182–203. PMID:24506485

  1. Trajectories of martian habitability.

    PubMed

    Cockell, Charles S

    2014-02-01

    Beginning from two plausible starting points-an uninhabited or inhabited Mars-this paper discusses the possible trajectories of martian habitability over time. On an uninhabited Mars, the trajectories follow paths determined by the abundance of uninhabitable environments and uninhabited habitats. On an inhabited Mars, the addition of a third environment type, inhabited habitats, results in other trajectories, including ones where the planet remains inhabited today or others where planetary-scale life extinction occurs. By identifying different trajectories of habitability, corresponding hypotheses can be described that allow for the various trajectories to be disentangled and ultimately a determination of which trajectory Mars has taken and the changing relative abundance of its constituent environments.

  2. Trajectories of martian habitability.

    PubMed

    Cockell, Charles S

    2014-02-01

    Beginning from two plausible starting points-an uninhabited or inhabited Mars-this paper discusses the possible trajectories of martian habitability over time. On an uninhabited Mars, the trajectories follow paths determined by the abundance of uninhabitable environments and uninhabited habitats. On an inhabited Mars, the addition of a third environment type, inhabited habitats, results in other trajectories, including ones where the planet remains inhabited today or others where planetary-scale life extinction occurs. By identifying different trajectories of habitability, corresponding hypotheses can be described that allow for the various trajectories to be disentangled and ultimately a determination of which trajectory Mars has taken and the changing relative abundance of its constituent environments. PMID:24506485

  3. Freezing Behavior of Stratospheric Sulfate Aerosols Inferred from Trajectory Studies

    NASA Technical Reports Server (NTRS)

    Tabazadeh, A.; Toon, O. B.; Hamill, Patrick

    1995-01-01

    Based on the trajectory analysis presented in this paper, a new mechanism is described for the freezing of the stratospheric sulfate aerosols. Temperature histories based on 10-day back trajectories for six ER-2 flights during AASE-I (1989) and AAOE (1987) are presented. The mechanism requires, as an initial step, the cooling of a H2SO4/H2O aerosol to low temperatures. If a cooling cycle is then followed up by a warming to approximately 196-198 K, the aerosols may freeze due to the growth of the crystallizing embryos formed at the colder temperature. The HNO3 absorbed at colder temperatures may increase the nucleation rate of the crystalling embryos and therefore influence the crystallization of the supercooled aerosols upon warming. Of all the ER-2 flights described, only the polar stratospheric clouds (PSC), observed on the flights of January 24, and 25, 1989 are consistent with the thermodynamics of liquid ternary solutions of H2SO4/HNO3/H2O (type Ib PSCs). For those two days, back trajectories indicate that the air mass was exposed to sulfuric acid tetrahydrate (SAT) melting temperatures about 24 hours prior to being sampled by the ER-2. Temperature histories, recent laboratory measurements, and the properties of glassy solids suggest that stratospheric H2SO4 aerosols may undergo a phase transition to SAT upon warming at approximately 198 K after going through a cooling cycle to about 194 K or lower.

  4. Constraining Aerosol Optical Models Using Ground-Based, Collocated Particle Size and Mass Measurements in Variable Air Mass Regimes During the 7-SEAS/Dongsha Experiment

    NASA Technical Reports Server (NTRS)

    Bell, Shaun W.; Hansell, Richard A.; Chow, Judith C.; Tsay, Si-Chee; Wang, Sheng-Hsiang; Ji, Qiang; Li, Can; Watson, John G.; Khlystov, Andrey

    2012-01-01

    During the spring of 2010, NASA Goddard's COMMIT ground-based mobile laboratory was stationed on Dongsha Island off the southwest coast of Taiwan, in preparation for the upcoming 2012 7-SEAS field campaign. The measurement period offered a unique opportunity for conducting detailed investigations of the optical properties of aerosols associated with different air mass regimes including background maritime and those contaminated by anthropogenic air pollution and mineral dust. What appears to be the first time for this region, a shortwave optical closure experiment for both scattering and absorption was attempted over a 12-day period during which aerosols exhibited the most change. Constraints to the optical model included combined SMPS and APS number concentration data for a continuum of fine and coarse-mode particle sizes up to PM2.5. We also take advantage of an IMPROVE chemical sampler to help constrain aerosol composition and mass partitioning of key elemental species including sea-salt, particulate organic matter, soil, non sea-salt sulphate, nitrate, and elemental carbon. Our results demonstrate that the observed aerosol scattering and absorption for these diverse air masses are reasonably captured by the model, where peak aerosol events and transitions between key aerosols types are evident. Signatures of heavy polluted aerosol composed mostly of ammonium and non sea-salt sulphate mixed with some dust with transitions to background sea-salt conditions are apparent in the absorption data, which is particularly reassuring owing to the large variability in the imaginary component of the refractive indices. Extinctive features at significantly smaller time scales than the one-day sample period of IMPROVE are more difficult to reproduce, as this requires further knowledge concerning the source apportionment of major chemical components in the model. Consistency between the measured and modeled optical parameters serves as an important link for advancing remote

  5. OMI tropospheric NO2 air mass factors over South America: effects of biomass burning aerosols

    NASA Astrophysics Data System (ADS)

    Castellanos, P.; Boersma, K. F.; Torres, O.; de Haan, J. F.

    2015-03-01

    Biomass burning is an important and uncertain source of aerosols and NOx (NO + NO2) to the atmosphere. OMI observations of tropospheric NO2 are essential for characterizing this emissions source, but inaccuracies in the retrieval of NO2 tropospheric columns due to the radiative effects of aerosols, especially light-absorbing carbonaceous aerosols, are not well understood. It has been shown that the O2-O2 effective cloud fraction and pressure retrieval is sensitive to aerosol optical and physical properties, including aerosol optical depth (AOD). Aerosols implicitly influence the tropospheric air mass factor (AMF) calculations used in the NO2 retrieval through the effective cloud parameters used in the independent pixel approximation. In this work, we explicitly account for the effects of biomass burning aerosols in the tropospheric NO2 AMF calculation by including collocated aerosol extinction vertical profile observations from the CALIOP instrument, and aerosol optical depth (AOD) and single scattering albedo (SSA) retrieved by the OMI near-UV aerosol algorithm (OMAERUV) in the DISAMAR radiative transfer model for cloud-free scenes. Tropospheric AMFs calculated with DISAMAR were benchmarked against AMFs reported in the Dutch OMI NO2 (DOMINO) retrieval; the mean and standard deviation (SD) of the difference was 0.6 ± 8%. Averaged over three successive South American biomass burning seasons (2006-2008), the spatial correlation in the 500 nm AOD retrieved by OMI and the 532 nm AOD retrieved by CALIOP was 0.6, and 72% of the daily OMAERUV AOD observations were within 0.3 of the CALIOP observations. Overall, tropospheric AMFs calculated with observed aerosol parameters were on average 10% higher than AMFs calculated with effective cloud parameters. For effective cloud radiance fractions less than 30%, or effective cloud pressures greater than 800 hPa, the difference between tropospheric AMFs based on implicit and explicit aerosol parameters is on average 6 and 3

  6. An ion-drag air mass-flow sensor for automotive applications

    SciTech Connect

    Malaczynski, G.W.; Schroeder, T. )

    1992-04-01

    An air-flow meter, developed primarily for the measurement of intake air flow into an internal combustion engine, is described. The well-known process of corona ion deflection in a gas flow together with proper electrode geometry and a detection scheme provides the conceptual basis for a humidity-insensitive ionic air-flow sensor. Output characteristics of the sensor, such as response time and range of operation, are discussed and compared with those of a production hot-wore meter for the type that is currently used with electronic fuel injection systems.

  7. Surface analysis using a new plasma assisted desorption/ionisation source for mass spectrometry in ambient air

    NASA Astrophysics Data System (ADS)

    Bowfield, A.; Barrett, D. A.; Alexander, M. R.; Ortori, C. A.; Rutten, F. M.; Salter, T. L.; Gilmore, I. S.; Bradley, J. W.

    2012-06-01

    The authors report on a modified micro-plasma assisted desorption/ionisation (PADI) device which creates plasma through the breakdown of ambient air rather than utilising an independent noble gas flow. This new micro-PADI device is used as an ion source for ambient mass spectrometry to analyse species released from the surfaces of polytetrafluoroethylene, and generic ibuprofen and paracetamol tablets through remote activation of the surface by the plasma. The mass spectra from these surfaces compare favourably to those produced by a PADI device constructed using an earlier design and confirm that the new ion source is an effective device which can be used to achieve ambient mass spectrometry with improved spatial resolution.

  8. Trajectory correction propulsion for TOPS

    NASA Technical Reports Server (NTRS)

    Long, H. R.; Bjorklund, R. A.

    1972-01-01

    A blowdown-pressurized hydrazine propulsion system was selected to provide trajectory correction impulse for outer planet flyby spacecraft as the result of cost/mass/reliability tradeoff analyses. Present hydrazine component and system technology and component designs were evaluated for application to the Thermoelectric Outer Planet Spacecraft (TOPS); while general hydrazine technology was adequate, component design changes were deemed necessary for TOPS-type missions. A prototype hydrazine propulsion system was fabricated and fired nine times for a total of 1600 s to demonstrate the operation and performance of the TOPS propulsion configuration. A flight-weight trajectory correction propulsion subsystem (TCPS) was designed for the TOPS based on actual and estimated advanced components.

  9. Mass

    SciTech Connect

    Quigg, Chris

    2007-12-05

    In the classical physics we inherited from Isaac Newton, mass does not arise, it simply is. The mass of a classical object is the sum of the masses of its parts. Albert Einstein showed that the mass of a body is a measure of its energy content, inviting us to consider the origins of mass. The protons we accelerate at Fermilab are prime examples of Einsteinian matter: nearly all of their mass arises from stored energy. Missing mass led to the discovery of the noble gases, and a new form of missing mass leads us to the notion of dark matter. Starting with a brief guided tour of the meanings of mass, the colloquium will explore the multiple origins of mass. We will see how far we have come toward understanding mass, and survey the issues that guide our research today.

  10. Ares I-X Best Estimated Trajectory Analysis and Results

    NASA Technical Reports Server (NTRS)

    Karlgaard, Christopher D.; Beck, Roger E.; Starr, Brett R.; Derry, Stephen D.; Brandon, Jay; Olds, Aaron D.

    2011-01-01

    The Ares I-X trajectory reconstruction produced best estimated trajectories of the flight test vehicle ascent through stage separation, and of the first and upper stage entries after separation. The trajectory reconstruction process combines on-board, ground-based, and atmospheric measurements to produce the trajectory estimates. The Ares I-X vehicle had a number of on-board and ground based sensors that were available, including inertial measurement units, radar, air-data, and weather balloons. However, due to problems with calibrations and/or data, not all of the sensor data were used. The trajectory estimate was generated using an Iterative Extended Kalman Filter algorithm, which is an industry standard processing algorithm for filtering and estimation applications. This paper describes the methodology and results of the trajectory reconstruction process, including flight data preprocessing and input uncertainties, trajectory estimation algorithms, output transformations, and comparisons with preflight predictions.

  11. A Comparison of the Red Green Blue (RGB) Air Mass Imagery and Hyperspectral Infrared Retrieved Profiles and NOAA G-IV Dropsondes

    NASA Technical Reports Server (NTRS)

    Berndt, Emily; Folmer, Michael; Dunion, Jason

    2014-01-01

    RGB air mass imagery is derived from multiple channels or paired channel differences. The combination of channels and channel differences means the resulting imagery does not represent a quantity or physical parameter such as brightness temperature in conventional single channel imagery. Without a specific quantity to reference, forecasters are often confused as to what RGB products represent. Hyperspectral infrared retrieved profiles and NOAA G-IV dropsondes provide insight about the vertical structure of the air mass represented on the RGB air mass imagery and are a first step to validating the imagery.

  12. A Distributed Trajectory-Oriented Approach to Managing Traffic Complexity

    NASA Technical Reports Server (NTRS)

    Idris, Husni; Wing, David J.; Vivona, Robert; Garcia-Chico, Jose-Luis

    2007-01-01

    In order to handle the expected increase in air traffic volume, the next generation air transportation system is moving towards a distributed control architecture, in which ground-based service providers such as controllers and traffic managers and air-based users such as pilots share responsibility for aircraft trajectory generation and management. While its architecture becomes more distributed, the goal of the Air Traffic Management (ATM) system remains to achieve objectives such as maintaining safety and efficiency. It is, therefore, critical to design appropriate control elements to ensure that aircraft and groundbased actions result in achieving these objectives without unduly restricting user-preferred trajectories. This paper presents a trajectory-oriented approach containing two such elements. One is a trajectory flexibility preservation function, by which aircraft plan their trajectories to preserve flexibility to accommodate unforeseen events. And the other is a trajectory constraint minimization function by which ground-based agents, in collaboration with air-based agents, impose just-enough restrictions on trajectories to achieve ATM objectives, such as separation assurance and flow management. The underlying hypothesis is that preserving trajectory flexibility of each individual aircraft naturally achieves the aggregate objective of avoiding excessive traffic complexity, and that trajectory flexibility is increased by minimizing constraints without jeopardizing the intended ATM objectives. The paper presents conceptually how the two functions operate in a distributed control architecture that includes self separation. The paper illustrates the concept through hypothetical scenarios involving conflict resolution and flow management. It presents a functional analysis of the interaction and information flow between the functions. It also presents an analytical framework for defining metrics and developing methods to preserve trajectory flexibility and

  13. Long-term Trend of Cold Air Mass Amount below a Designated Potential Temperature in Northern and Southern Hemisphere Winters with 7 Different Reanalysis Datasets

    NASA Astrophysics Data System (ADS)

    Kanno, Y.; Abdillah, M. R.; Iwasaki, T.

    2015-12-01

    This study addresses that the hemispheric total cold air mass amount defined below a threshold potential temperature of 280 K is a good indicator of the long-term trend of climate change in the polar region. We demonstrate quantitative analyses of warming trend in the Northern Hemisphere (NH) and Southern Hemisphere (SH) winters, using 7 different reanalysis datasets (JRA-55, JRA-55C, JRA-55AMIP, ERA-interim, CFSR, JRA-25, NCEP-NCAR). Hemispheric total cold air mass amount in the NH winter exhibit a statistically significant decreasing trend in all reanalysis datasets at a rate about -1.37 to -0.77% per decade over the period 1959-2012 and at a rate about -1.57 to -0.82% per decade over 1980-2012. There is no statistically significant trend in the equatorward cold air mass flux across latitude of 45N, which is an indicator for hemispheric-scale cold air outbreak, over the period 1980-2012 except for NCEP-NCAR reanalysis dataset which shows substantial decreasing trend of about -3.28% per decade. The spatial distribution of the long-term trend of cold air mass amount in the NH winter is almost consistent among reanalysis datasets except for JRA-55AMIP over the period 1980-2012. Cold air mass amount increases over Central Siberia, Kamchatka peninsula, and Bering Sea, while it decreases over Norwegian Sea, Barents Sea, Kara Sea, Greenland, Canada, Northern part of United States, and East Asia. In the SH winter, on the other hand, there is a large discrepancy in hemispheric total cold air mass amount and equatorward cold air mass flux across latitude of 50S over the period 1980-2010 among reanalysis datasets. This result indicate that there is a large uncertainty in the long-term trend of cold air mass amount in the SH winter.

  14. Retrospective screening of pesticide metabolites in ambient air using liquid chromatography coupled to high-resolution mass spectrometry.

    PubMed

    López, Antonio; Yusà, Vicent; Millet, Maurice; Coscollà, Clara

    2016-04-01

    A new methodology for the retrospective screening of pesticide metabolites in ambient air was developed, using liquid chromatography coupled to Orbitrap high-resolution mass spectrometry (UHPLC-HRMS), including two systematic workflows (i) post-run target screening (suspect screening) and (ii) non-target screening. An accurate-mass database was built and used for the post-run screening analysis. The database contained 240 pesticide metabolites found in different matrixes such as air, soil, water, plants, animals and humans. For non-target analysis, a "fragmentation-degradation" relationship strategy was selected. The proposed methodology was applied to 31 air samples (PM10) collected in the Valencian Region (Spain). In the post-target analysis 34 metabolites were identified, of which 11 (3-ketocarburan, carbofuran-7-phenol, carbendazim, desmethylisoproturon, ethiofencarb-sulfoxide, malaoxon, methiocarb-sulfoxide, N-(2-ethyl-6-methylphenyl)-L-alanine, omethoate, 2-hydroxy-terbuthylazine, and THPAM) were confirmed using analytical standards. The semiquantitative estimated concentration ranged between 6.78 and 198.31 pg m(-3). Likewise, two unknown degradation products of malaoxon and fenhexamid were elucidated in the non-target screening. PMID:26838378

  15. 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.

  16. Retrospective screening of pesticide metabolites in ambient air using liquid chromatography coupled to high-resolution mass spectrometry.

    PubMed

    López, Antonio; Yusà, Vicent; Millet, Maurice; Coscollà, Clara

    2016-04-01

    A new methodology for the retrospective screening of pesticide metabolites in ambient air was developed, using liquid chromatography coupled to Orbitrap high-resolution mass spectrometry (UHPLC-HRMS), including two systematic workflows (i) post-run target screening (suspect screening) and (ii) non-target screening. An accurate-mass database was built and used for the post-run screening analysis. The database contained 240 pesticide metabolites found in different matrixes such as air, soil, water, plants, animals and humans. For non-target analysis, a "fragmentation-degradation" relationship strategy was selected. The proposed methodology was applied to 31 air samples (PM10) collected in the Valencian Region (Spain). In the post-target analysis 34 metabolites were identified, of which 11 (3-ketocarburan, carbofuran-7-phenol, carbendazim, desmethylisoproturon, ethiofencarb-sulfoxide, malaoxon, methiocarb-sulfoxide, N-(2-ethyl-6-methylphenyl)-L-alanine, omethoate, 2-hydroxy-terbuthylazine, and THPAM) were confirmed using analytical standards. The semiquantitative estimated concentration ranged between 6.78 and 198.31 pg m(-3). Likewise, two unknown degradation products of malaoxon and fenhexamid were elucidated in the non-target screening.

  17. OMI tropospheric NO2 air mass factors over South America: effects of biomass burning aerosols

    NASA Astrophysics Data System (ADS)

    Castellanos, P.; Boersma, K. F.; Torres, O.; de Haan, J. F.

    2015-09-01

    Biomass burning is an important and uncertain source of aerosols and NOx (NO + NO2) to the atmosphere. Satellite observations of tropospheric NO2 are essential for characterizing this emissions source, but inaccuracies in the retrieval of NO2 tropospheric columns due to the radiative effects of aerosols, especially light-absorbing carbonaceous aerosols, are not well understood. It has been shown that the O2-O2 effective cloud fraction and pressure retrieval is sensitive to aerosol optical and physical properties, including aerosol optical depth (AOD). Aerosols implicitly influence the tropospheric air mass factor (AMF) calculations used in the NO2 retrieval through the effective cloud parameters used in the independent pixel approximation. In this work, we explicitly account for the effects of biomass burning aerosols in the Ozone Monitoring Instrument (OMI) tropospheric NO2 AMF calculation for cloud-free scenes. We do so by including collocated aerosol extinction vertical profile observations from the CALIOP instrument, and aerosol optical depth (AOD) and single scattering albedo (SSA) retrieved by the OMI near-UV aerosol algorithm (OMAERUV) in the DISAMAR radiative transfer model. Tropospheric AMFs calculated with DISAMAR were benchmarked against AMFs reported in the Dutch OMI NO2 (DOMINO) retrieval; the mean and standard deviation of the difference was 0.6 ± 8 %. Averaged over three successive South American biomass burning seasons (2006-2008), the spatial correlation in the 500 nm AOD retrieved by OMI and the 532 nm AOD retrieved by CALIOP was 0.6, and 68 % of the daily OMAERUV AOD observations were within 30 % of the CALIOP observations. Overall, tropospheric AMFs calculated with observed aerosol parameters were on average 10 % higher than AMFs calculated with effective cloud parameters. For effective cloud radiance fractions less than 30 %, or effective cloud pressures greater than 800 hPa, the difference between tropospheric AMFs based on implicit and

  18. An automated gas chromatography time-of-flight mass spectrometry instrument for the quantitative analysis of halocarbons in air

    NASA Astrophysics Data System (ADS)

    Obersteiner, F.; Bönisch, H.; Engel, A.

    2016-01-01

    We present the characterization and application of a new gas chromatography time-of-flight mass spectrometry instrument (GC-TOFMS) for the quantitative analysis of halocarbons in air samples. The setup comprises three fundamental enhancements compared to our earlier work (Hoker et al., 2015): (1) full automation, (2) a mass resolving power R = m/Δm of the TOFMS (Tofwerk AG, Switzerland) increased up to 4000 and (3) a fully accessible data format of the mass spectrometric data. Automation in combination with the accessible data allowed an in-depth characterization of the instrument. Mass accuracy was found to be approximately 5 ppm in mean after automatic recalibration of the mass axis in each measurement. A TOFMS configuration giving R = 3500 was chosen to provide an R-to-sensitivity ratio suitable for our purpose. Calculated detection limits are as low as a few femtograms by means of the accurate mass information. The precision for substance quantification was 0.15 % at the best for an individual measurement and in general mainly determined by the signal-to-noise ratio of the chromatographic peak. Detector non-linearity was found to be insignificant up to a mixing ratio of roughly 150 ppt at 0.5 L sampled volume. At higher concentrations, non-linearities of a few percent were observed (precision level: 0.2 %) but could be attributed to a potential source within the detection system. A straightforward correction for those non-linearities was applied in data processing, again by exploiting the accurate mass information. Based on the overall characterization results, the GC-TOFMS instrument was found to be very well suited for the task of quantitative halocarbon trace gas observation and a big step forward compared to scanning, quadrupole MS with low mass resolving power and a TOFMS technique reported to be non-linear and restricted by a small dynamical range.

  19. PANTHER. Trajectory Analysis

    SciTech Connect

    Rintoul, Mark Daniel; Wilson, Andrew T.; Valicka, Christopher G.; Kegelmeyer, W. Philip; Shead, Timothy M.; Newton, Benjamin D.; Czuchlewski, Kristina Rodriguez

    2015-09-01

    We want to organize a body of trajectories in order to identify, search for, classify and predict behavior among objects such as aircraft and ships. Existing compari- son functions such as the Fr'echet distance are computationally expensive and yield counterintuitive results in some cases. We propose an approach using feature vectors whose components represent succinctly the salient information in trajectories. These features incorporate basic information such as total distance traveled and distance be- tween start/stop points as well as geometric features related to the properties of the convex hull, trajectory curvature and general distance geometry. Additionally, these features can generally be mapped easily to behaviors of interest to humans that are searching large databases. Most of these geometric features are invariant under rigid transformation. We demonstrate the use of different subsets of these features to iden- tify trajectories similar to an exemplar, cluster a database of several hundred thousand trajectories, predict destination and apply unsupervised machine learning algorithms.

  20. Complexity Science Applications to Dynamic Trajectory Management: Research Strategies

    NASA Technical Reports Server (NTRS)

    Sawhill, Bruce; Herriot, James; Holmes, Bruce J.; Alexandrov, Natalia

    2009-01-01

    The promise of the Next Generation Air Transportation System (NextGen) is strongly tied to the concept of trajectory-based operations in the national airspace system. Existing efforts to develop trajectory management concepts are largely focused on individual trajectories, optimized independently, then de-conflicted among each other, and individually re-optimized, as possible. The benefits in capacity, fuel, and time are valuable, though perhaps could be greater through alternative strategies. The concept of agent-based trajectories offers a strategy for automation of simultaneous multiple trajectory management. The anticipated result of the strategy would be dynamic management of multiple trajectories with interacting and interdependent outcomes that satisfy multiple, conflicting constraints. These constraints would include the business case for operators, the capacity case for the Air Navigation Service Provider (ANSP), and the environmental case for noise and emissions. The benefits in capacity, fuel, and time might be improved over those possible under individual trajectory management approaches. The proposed approach relies on computational agent-based modeling (ABM), combinatorial mathematics, as well as application of "traffic physics" concepts to the challenge, and modeling and simulation capabilities. The proposed strategy could support transforming air traffic control from managing individual aircraft behaviors to managing systemic behavior of air traffic in the NAS. A system built on the approach could provide the ability to know when regions of airspace approach being "full," that is, having non-viable local solution space for optimizing trajectories in advance.

  1. Distributed Traffic Complexity Management by Preserving Trajectory Flexibility

    NASA Technical Reports Server (NTRS)

    Idris, Husni; Vivona, Robert A.; Garcia-Chico, Jose-Luis; Wing, David J.

    2007-01-01

    In order to handle the expected increase in air traffic volume, the next generation air transportation system is moving towards a distributed control architecture, in which groundbased service providers such as controllers and traffic managers and air-based users such as pilots share responsibility for aircraft trajectory generation and management. This paper presents preliminary research investigating a distributed trajectory-oriented approach to manage traffic complexity, based on preserving trajectory flexibility. The underlying hypotheses are that preserving trajectory flexibility autonomously by aircraft naturally achieves the aggregate objective of avoiding excessive traffic complexity, and that trajectory flexibility is increased by collaboratively minimizing trajectory constraints without jeopardizing the intended air traffic management objectives. This paper presents an analytical framework in which flexibility is defined in terms of robustness and adaptability to disturbances and preliminary metrics are proposed that can be used to preserve trajectory flexibility. The hypothesized impacts are illustrated through analyzing a trajectory solution space in a simple scenario with only speed as a degree of freedom, and in constraint situations involving meeting multiple times of arrival and resolving conflicts.

  2. [Determination of volatile organic compounds in ambient air by thermal desorption-gas chromatography-triple quadrupole tandem mass spectrometry].

    PubMed

    Feng, Lili; Hu, Xiaofang; Yu, Xiaojuan; Zhang, Wenying

    2016-02-01

    A method was established for the simultaneous determination of 23 volatile organic compounds (VOCs) in ambient air with combination of thermal desorption (TD) and gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS). The air samples were collected by active sampling method using Tenax-TA sorbent tubes, and desorbed by thermal desorption. The analytes were determined by GC-MS/MS in selected reaction monitoring (SRM) mode, and internal standard method was applied to quantify the VOCs. The results of all the 23 VOCs showed good linearities in low level (0. 01-1 ng) and high level (1-100 ng) with all the correlation coefficients (r2) more than 0. 99. The method quantification limits were between 0. 000 08-1 µg/m3. The method was validated by means of recovery experiments (n = 6) at three spiked levels of 2, 10 and 50 ng. The recoveries between 77% and 124% were generally obtained. The relative standard deviations (RSDs) in all cases were lower than 20%, except for chlorobenzene at the low spiked level. The developed method was applied to determine VOCs in ambient air collected at three sites in Shanghai. Several compounds, like benzene, toluene, ethylbenzene, m-xylenes, p-xylenes, styrene, 1, 2, 4-trimethylbenzene and hexachlorobutadiene were detected and confirmed in all the samples analyzed. The method is highly accurate, reliable and sensitive for monitoring the VOCs in ambient air. PMID:27382728

  3. Measurement of volatile plant compounds in field ambient air by thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Cai, Xiao-Ming; Xu, Xiu-Xiu; Bian, Lei; Luo, Zong-Xiu; Chen, Zong-Mao

    2015-12-01

    Determination of volatile plant compounds in field ambient air is important to understand chemical communication between plants and insects and will aid the development of semiochemicals from plants for pest control. In this study, a thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method was developed to measure ultra-trace levels of volatile plant compounds in field ambient air. The desorption parameters of TD, including sorbent tube material, tube desorption temperature, desorption time, and cold trap temperature, were selected and optimized. In GC-MS analysis, the selected ion monitoring mode was used for enhanced sensitivity and selectivity. This method was sufficiently sensitive to detect part-per-trillion levels of volatile plant compounds in field ambient air. Laboratory and field evaluation revealed that the method presented high precision and accuracy. Field studies indicated that the background odor of tea plantations contained some common volatile plant compounds, such as (Z)-3-hexenol, methyl salicylate, and (E)-ocimene, at concentrations ranging from 1 to 3400 ng m(-3). In addition, the background odor in summer was more abundant in quality and quantity than in autumn. Relative to previous methods, the TD-GC-MS method is more sensitive, permitting accurate qualitative and quantitative measurements of volatile plant compounds in field ambient air. PMID:26493981

  4. Measurement of volatile plant compounds in field ambient air by thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Cai, Xiao-Ming; Xu, Xiu-Xiu; Bian, Lei; Luo, Zong-Xiu; Chen, Zong-Mao

    2015-12-01

    Determination of volatile plant compounds in field ambient air is important to understand chemical communication between plants and insects and will aid the development of semiochemicals from plants for pest control. In this study, a thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method was developed to measure ultra-trace levels of volatile plant compounds in field ambient air. The desorption parameters of TD, including sorbent tube material, tube desorption temperature, desorption time, and cold trap temperature, were selected and optimized. In GC-MS analysis, the selected ion monitoring mode was used for enhanced sensitivity and selectivity. This method was sufficiently sensitive to detect part-per-trillion levels of volatile plant compounds in field ambient air. Laboratory and field evaluation revealed that the method presented high precision and accuracy. Field studies indicated that the background odor of tea plantations contained some common volatile plant compounds, such as (Z)-3-hexenol, methyl salicylate, and (E)-ocimene, at concentrations ranging from 1 to 3400 ng m(-3). In addition, the background odor in summer was more abundant in quality and quantity than in autumn. Relative to previous methods, the TD-GC-MS method is more sensitive, permitting accurate qualitative and quantitative measurements of volatile plant compounds in field ambient air.

  5. Socioeconomic inequalities in health trajectories in Switzerland: are trajectories diverging as people age?

    PubMed

    Cullati, Stéphane

    2015-06-01

    Do socioeconomic differences in health status increase as people age, reflecting cumulative advantage or disadvantage in health trajectories? Life course research hypothesises that cumulative advantage/disadvantage (CAD) is an important underlying social process that shape inequalities as people age. The objective of this study is to examine whether health trajectories are diverging as people age across socioeconomic positions (education, employment status and income). In a random sample of 3,665 respondents living in Switzerland (Swiss Household Panel 2004-2011), trajectories of self-rated health, body mass index, depression and medicated functioning were examined with multilevel regression models. The results showed that employment status and income were associated with diverging health trajectories among men; however, only a few associations supported the CAD hypothesis. Education was rarely associated with diverging health trajectories. In conclusion, little evidence was found to support the CAD model.

  6. Modeling 3D conjugate heat and mass transfer for turbulent air drying of Chilean papaya in a direct contact dryer

    NASA Astrophysics Data System (ADS)

    Lemus-Mondaca, Roberto A.; Vega-Gálvez, Antonio; Zambra, Carlos E.; Moraga, Nelson O.

    2016-03-01

    A 3D model considering heat and mass transfer for food dehydration inside a direct contact dryer is studied. The k- ɛ model is used to describe turbulent air flow. The samples thermophysical properties as density, specific heat, and thermal conductivity are assumed to vary non-linearly with temperature. FVM, SIMPLE algorithm based on a FORTRAN code are used. Results unsteady velocity, temperature, moisture, kinetic energy and dissipation rate for the air flow are presented, whilst temperature and moisture values for the food also are presented. The validation procedure includes a comparison with experimental and numerical temperature and moisture content results obtained from experimental data, reaching a deviation 7-10 %. In addition, this turbulent k- ɛ model provided a better understanding of the transport phenomenon inside the dryer and sample.

  7. Continental Land Mass Air Traffic Control (COLM ATC). [using three artificial satellite configurations

    NASA Technical Reports Server (NTRS)

    Pecar, J. A.; Henrich, J. E.

    1973-01-01

    The application of various satellite systems and techniques relative to providing air traffic control services for the continental United States was studied. Three satellite configurations were reviewed. The characteristics and capabilities of the satellites are described. The study includes consideration for the various ranging waveforms, multiple access alternatives, and the power and bandwidth required as a function of the number of users.

  8. Aerosol composition and properties variation at the ground and over the column under different air masses advection in South Italy.

    PubMed

    Pavese, G; Lettino, A; Calvello, M; Esposito, F; Fiore, S

    2016-04-01

    Aerosol composition and properties variation under the advection of different air masses were investigated, as case studies, by contemporary measurements over the atmospheric column and at the ground in a semi-rural site in South Italy. The absence of local strong sources in this area allowed to characterize background aerosol and to compare particle mixing effects under various atmospheric circulation conditions. Aerosol optical depth (AOD) and Ǻngström parameters from radiometric measurements allowed the detection and identification of polluted, dust, and volcanic atmospheric conditions. AODs were the input for a suitable model to evaluate the columnar aerosol composition, according to six main atmospheric components (water-soluble, soot, sea salt accumulation, sea salt coarse, mineral dus,t and biological). Scanning electron microscope (SEM) analysis of particulate sampled with a 13-stage impactor at the ground showed not only fingerprints typical of the different air masses but also the effects of transport and aging on atmospheric particles, suggesting processes that changed their chemical and optical properties. Background columnar aerosol was characterized by 72% of water-soluble and soot, in agreement with ground-based findings that highlighted 60% of contribution from anthropogenic carbonate particles and soot. In general, a good agreement between ground-based and columnar results was observed. Under the advection of trans-boundary air masses, water-soluble and soot were always present in columnar aerosol, whereas, in variable percentages, sea salt and mineral particles characterized both dust and volcanic conditions. At the ground, sulfates characterized the amorphous matrix produced in finer stages by the evaporation of solutions of organic and inorganic aerosols. Sulfates were also one of the key players involved in heterogeneous chemical reactions, producing complex secondary aerosol, as such clay-sulfate internally mixed particle externally mixed

  9. A vector-dyadic development of the equations of motion for N-coupled flexible bodies and point masses. [spacecraft trajectories

    NASA Technical Reports Server (NTRS)

    Frisch, H. P.

    1975-01-01

    The equations of motion for a system of coupled flexible bodies, rigid bodies, point masses, and symmetric wheels were derived. The equations were cast into a partitioned matrix form in which certain partitions became nontrivial when the effects of flexibility were treated. The equations are shown to contract to the coupled rigid body equations or expand to the coupled flexible body equations all within the same basic framework. Furthermore, the coefficient matrix always has the computationally desirable property of symmetry. Making use of the derived equations, a comparison was made between the equations which described a flexible body model and those which described a rigid body model of the same elastic appendage attached to an arbitrary coupled body system. From the comparison, equivalence relations were developed which defined how the two modeling approaches described identical dynamic effects.

  10. Trajectory of the mt. St. Augustine 1976 eruption ash cloud.

    PubMed

    Meinel, A B; Meinel, M P; Shaw, G E

    1976-07-30

    The ash clouds from the 23 January 1976 eruption of Mt. St. Augustine in Alaska drifted over Arizona on 25 January at an altitude of 6 kilometers as deduced from air trajectories and the observation of an unusual cloud.

  11. Trajectory Browser Website

    NASA Technical Reports Server (NTRS)

    Foster, Cyrus; Jaroux, Belgacem A.

    2012-01-01

    The Trajectory Browser is a web-based tool developed at the NASA Ames Research Center to be used for the preliminary assessment of trajectories to small-bodies and planets and for providing relevant launch date, time-of-flight and V requirements. The site hosts a database of transfer trajectories from Earth to asteroids and planets for various types of missions such as rendezvous, sample return or flybys. A search engine allows the user to find trajectories meeting desired constraints on the launch window, mission duration and delta V capability, while a trajectory viewer tool allows the visualization of the heliocentric trajectory and the detailed mission itinerary. The anticipated user base of this tool consists primarily of scientists and engineers designing interplanetary missions in the context of pre-phase A studies, particularly for performing accessibility surveys to large populations of small-bodies. The educational potential of the website is also recognized for academia and the public with regards to trajectory design, a field that has generally been poorly understood by the public. The website is currently hosted on NASA-internal URL http://trajbrowser.arc.nasa.gov/ with plans for a public release as soon as development is complete.

  12. Detection of biological particles in ambient air using Bio-Aerosol Mass Spectrometry

    SciTech Connect

    McJimpsey, E L; Steele, P T; Coffee, K R; Fergenson, D P; Riot, V J; Woods, B W; Gard, E E; Frank, M; Tobias, H J; Lebrilla, C

    2006-03-16

    The Bio-Aerosol Mass Spectrometry (BAMS) system is an instrument used for the real time detection and identification of biological aerosols. Particles are drawn from the atmosphere directly into vacuum and tracked as they scatter light from several continuous wave lasers. After tracking, the fluorescence of individual particles is excited by a pulsed 266nm or 355nm laser. Molecules from those particles with appropriate fluorescence properties are subsequently desorbed and ionized using a pulsed 266nm laser. Resulting ions are analyzed in a dual polarity mass spectrometer. During two field deployments at the San Francisco International Airport, millions of ambient particles were analyzed and a small but significant fraction were found to have fluorescent properties similar to Bacillus spores and vegetative cells. Further separation of non-biological background particles from potential biological particles was accomplished using laser desorption/ionization mass spectrometry. This has been shown to enable some level of species differentiation in specific cases, but the creation and observation of higher mass ions is needed to enable a higher level of specificity across more species. A soft ionization technique, matrix-assisted laser desorption/ionization (MALDI) is being investigated for this purpose. MALDI is particularly well suited for mass analysis of biomolecules since it allows for the generation of molecular ions from large mass compounds that would fragment under normal irradiation. Some of the initial results from a modified BAMS system utilizing this technique are described.

  13. Reentry trajectory optimization and control

    NASA Astrophysics Data System (ADS)

    Strohmaier, P.; Kiefer, A.; Burkhardt, D.; Horn, K.

    1990-06-01

    There are several possible methods to increase the cross range capability of a winged reentry vehicle, for instance, skip trajectories, a powered cruise phase, or high lift/drag ratio flight. However, most of these alternative descent strategies have not yet been investigated sufficiently with respect to aero-thermodynamic effects and the design of the thermal protection system. This problem is treated by two different means. First, a nominal reentry trajectory is generated based on a phase concept, and then the same problem is again solved using a numerical optimization code to determine the control functions. The nominal reentry trajectory design presented first subdivides the total reentry trajectory into several segments with partially constant control/state parameters such as maximum heat flux and deceleration. The optimal conditions for a given segment can then be selected. In contrast, the parameterized optimization code selects the control functions freely. Both approaches consider a mass point simulation which uses realistic model assumptions for atmosphere, earth and gravity. Likewise, both approaches satisfy all flight regime limitations and boundary conditions such as thermal constraints throughout the flight path and specified speed and altitude at the final time. For the optimization of high cross reentry trajectories the cross range per total absorbed heat represents an appropriate cost function. The optimization code delivers quite a different flight strategy than that usually generated by the nominal reentry design program, first flying longer along the temperature boundary at highest possible angle of attack (AOAs) (utilizing higher average turn rates), and afterwards performing flare-dive segments to reduce heat flux and to increase range. Finally, the aspect of guiding the nominal or optimized reentry trajectory during a cross range flight is considered. The vertical guidance is performed with both angles of attack and roll angle control. The

  14. Matching trajectory optimization and nonlinear tracking control for HALE

    NASA Astrophysics Data System (ADS)

    Lee, Sangjong; Jang, Jieun; Ryu, Hyeok; Lee, Kyun Ho

    2014-11-01

    This paper concerns optimal trajectory generation and nonlinear tracking control for stratospheric airship platform of VIA-200. To compensate for the mismatch between the point-mass model of optimal trajectory and the 6-DOF model of the nonlinear tracking problem, a new matching trajectory optimization approach is proposed. The proposed idea reduces the dissimilarity of both problems and reduces the uncertainties in the nonlinear equations of motion for stratospheric airship. In addition, its refined optimal trajectories yield better results under jet stream conditions during flight. The resultant optimal trajectories of VIA-200 are full three-dimensional ascent flight trajectories reflecting the realistic constraints of flight conditions and airship performance with and without a jet stream. Finally, 6-DOF nonlinear equations of motion are derived, including a moving wind field, and the vectorial backstepping approach is applied. The desirable tracking performance is demonstrated that application of the proposed matching optimization method enables the smooth linkage of trajectory optimization to tracking control problems.

  15. A demonstration and evaluation of trajectory mapping

    SciTech Connect

    Morris, G.A.

    1994-09-01

    Problem of creating synoptic maps from asynoptically gathered data has prompted the development of a number schemes, the most notable being the Kalman filter, Salby-Fourier technique, and constituent reconstruction. This thesis presents a new technique, called trajectory mapping, which employs a simple model of air parcel motion to create synoptic maps from asynoptically gathered data. Four sources of trajectory mapping errors were analyzed; results showed that (1) the computational error is negligible; (2) measurement uncertainties can result in errors which grow with time scales of a week; (3) isentropic approximations lead to errors characterized by time scales of a week; and (4) wind field inaccuracies can cause significant errors in individual parcel trajectories in a matter of hours. All the studies, however, indicated that while individual trajectory errors can grow rapidly, constituent distributions, such as on trajectory maps, are much more robust, maintaining a high level of accuracy for periods on the order of several weeks. This technique was successfully applied to a variety of problems:(1) dynamical wave- breaking events; (2) satellite data validation for both instrument accuracy and precision; and (3) accuracy of meteorological wind fields. Such demonstrations imply that trajectory mapping will become an important tool in answering questions of global change, particularly the issue of ozone depletion.

  16. Nonlinear trajectory navigation

    NASA Astrophysics Data System (ADS)

    Park, Sang H.

    Trajectory navigation entails the solution of many different problems that arise due to uncertain knowledge of the spacecraft state, including orbit prediction, correction maneuver design, and trajectory estimation. In practice, these problems are usually solved based on an assumption that linear dynamical models sufficiently approximate the local trajectory dynamics and their associated statistics. However, astrodynamics problems are nonlinear in general and linear spacecraft dynamics models can fail to characterize the true trajectory dynamics when the system is subject to a highly unstable environment or when mapped over a long time period. This limits the performance of traditional navigation techniques and can make it difficult to perform precision analysis or robust navigation. This dissertation presents an alternate method for spacecraft trajectory navigation based on a nonlinear local trajectory model and their statistics in an analytic framework. For a given reference trajectory, we first solve for the higher order Taylor series terms that describe the localized nonlinear motion and develop an analytic expression for the relative solution flow. We then discuss the nonlinear dynamical mapping of a spacecraft's probability density function by solving the Fokker-Planck equation for a deterministic system. From this result we derive an analytic method for orbit uncertainty propagation which can replicate Monte-Carlo simulations with the benefit of added flexibility in initial orbit statistics. Using this approach, we introduce the concept of the statistically correct trajectory where we directly incorporate statistical information about an orbit state into the trajectory design process. As an extension of this concept, we define a nonlinear statistical targeting method where we solve for a correction maneuver which intercepts the desired target on average. Then we apply our results to a Bayesian filtering problem to obtain a general filtering algorithm for

  17. A Study of the Ozone Formation by Ensemble Back Trajectory-process Analysis Using the Eta-CMAQ Forecast Model over the Northeastern U.S. During the 2004 ICARTT Period

    EPA Science Inventory

    The integrated process rates (IPR) estimated by the Eta-CMAQ model at grid cells along the trajectory of the air mass transport path were analyzed to quantitatively investigate the relative importance of physical and chemical processes for O3 formation and evolution ov...

  18. Distributions, Sources, and Backward Trajectories of Atmospheric Polycyclic Aromatic Hydrocarbons at Lake Small Baiyangdian, Northern China

    PubMed Central

    Qin, Ning; Kong, Xiang-Zhen; Zhu, Ying; He, Wei; He, Qi-Shuang; Yang, Bin; Ou-Yang, Hui-Ling; Liu, Wen-Xiu; Wang, Qing-Mei; Xu, Fu-Liu

    2012-01-01

    Air samples were collected seasonally at Lake Small Baiyangdian, a shallow lake in northern China, between October 2007 and September 2008. Gas phase, particulate phase and dust fall concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured using a gas chromatograph-mass spectrometer (GC-MS). The distribution and partitioning of atmospheric PAHs were studied, and the major sources were identified; the backward trajectories of air masses starting from the center of Lake Small Baiyangdian were calculated for the entire year. The following results were obtained: (1) The total concentration of 16 priority controlled PAHs (PAH16) in the gas phase was 417.2 ± 299.8 ng·m−3, in the particulate phase was 150.9 ± 99.2 ng·m−3, and in dust fall was 6930.2 ± 3206.5 ng·g−1. (2) Vehicle emission, coal combustion, and biomass combustion were the major sources in the Small Baiyangdian atmosphere and accounted for 28.9%, 45.1% and 26.0% of the total PAHs, respectively. (3) Winter was dominated by relatively greater PAHs polluted northwesterly air mass pathways. Summer showed a dominant relatively clean southern pathway, whereas the trajectories in autumn and spring might be associated with high pollution from Shanxi or Henan province. PMID:23118612

  19. Plasma flame for mass purification of contaminated air with chemical and biological warfare agents

    SciTech Connect

    Uhm, Han S.; Shin, Dong H.; Hong, Yong C.

    2006-09-18

    An elimination of airborne simulated chemical and biological warfare agents was carried out by making use of a plasma flame made of atmospheric plasma and a fuel-burning flame, which can purify the interior air of a large volume in isolated spaces such as buildings, public transportation systems, and military vehicles. The plasma flame generator consists of a microwave plasma torch connected in series to a fuel injector and a reaction chamber. For example, a reaction chamber, with the dimensions of a 22 cm diameter and 30 cm length, purifies an airflow rate of 5000 lpm contaminated with toluene (the simulated chemical agent) and soot from a diesel engine (the simulated aerosol for biological agents). Large volumes of purification by the plasma flame will free mankind from the threat of airborne warfare agents. The plasma flame may also effectively purify air that is contaminated with volatile organic compounds, in addition to eliminating soot from diesel engines as an environmental application.

  20. Mass transfer of volatile organic compounds from drinking water to indoor air: The role of residential dishwashers

    SciTech Connect

    Howard-Reed, C.; Corsi, R.L.; Moya, J.

    1999-07-01

    Contaminated tap water may be a source of volatile organic compounds (VOCs) in residential indoor air. To better understand the extent and impact of chemical emissions from this source, a two-phase mass balance model was developed based on mass transfer kinetics between each phase. Twenty-nine experiments were completed using a residential dishwasher to determine model parameters. During each experiment, inflow water was spiked with a cocktail of chemical tracers with a wide range of physicochemical properties. In each case, the effects of water temperature, detergent, and dish-loading pattern on chemical stripping efficiencies and mass transfer coefficients were determined. Dishwasher headspace ventilation rates were also measured using an isobutylene tracer gas. Chemical stripping efficiencies for a single cycle ranged from 18% to 55% for acetone, from 96% to 98% for toluene, and from 97% to 98% for ethylbenzene and were consistently 100% for cyclohexane. Experimental results indicate that dishwashers have a relatively low but continuous ventilation rate that results in significant chemical storage within the headspace of the dishwasher. In conjunction with relatively high mass transfer coefficients, low ventilation rates generally lead to emissions that are limited by equilibrium conditions after approximately 1--2 min of dishwasher operation.

  1. MAVEN's Trajectory to Mars

    NASA Video Gallery

    This movie shows the cruise trajectory of NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission, which was launched on Nov. 18, 2013. It will arrive at Mars on Sept. 21, 2014, to explore th...

  2. Ornithopter transition trajectories

    NASA Astrophysics Data System (ADS)

    Dietl, John M.; Garcia, Ephrahim

    2010-04-01

    The design of stable trim conditions for forward flight and for hover has been achieved. In forward flight, an ornithopter is configured like a conventional airplane or large bird. Its fuselage is essentially horizontal and the wings heave in a vertical plane. In hover, however, the body pitches vertically so that the wing stroke in the horizontal plane. Thrust directed downward, the vehicle remains aloft while the downdraft envelops the tail to provide enough flow for vehicle control and stabilization. To connect these trajectories dynamically is the goal. The naïve approach-to choose two stable trajectories and switch between them-has been accomplished. A new approach is to establish an open-loop trajectory through a trajectory optimization algorithm-optimized for shortest altitude drop, shortest stopping distance, or lowest energy consumption.

  3. Automated Cooperative Trajectories

    NASA Technical Reports Server (NTRS)

    Hanson, Curt; Pahle, Joseph; Brown, Nelson

    2015-01-01

    This presentation is an overview of the Automated Cooperative Trajectories project. An introduction to the phenomena of wake vortices is given, along with a summary of past research into the possibility of extracting energy from the wake by flying close parallel trajectories. Challenges and barriers to adoption of civilian automatic wake surfing technology are identified. A hardware-in-the-loop simulation is described that will support future research. Finally, a roadmap for future research and technology transition is proposed.

  4. Towards a Formal Semantics of Flight Plans and Trajectories

    NASA Technical Reports Server (NTRS)

    Hagen, George E.; Butler, Ricky W.

    2014-01-01

    In the National Airspace System, ight plans are often used only as a planning tool by air trac controllers and aircraft operators. These plans are implicitly translated into trajectories by the pilot or by the ight management system, and subsequently own by the aircraft. This translation process inevitably introduces di erences between the plan and the trajectory. However, given the current intended usage, exact correspondence between the plan and the trajectory is not needed. To achieve greater capacity and eciency, future air trac management concepts are being designed around the use of trajectories where predictability is extremely important. In this paper, a mathematical relationship between ight plans and trajectories is explored with the goal of making feasible, highly accurate predictions of future positions and velocities of aircraft. The goal here is to describe, in mathematically precise detail, a formal language of trajectories, whereby all receivers of the trajectory information will be able to arrive at precisely the same trajectory predication and to do this without having aircraft broadcast a large amount of data. Although even a four-dimensional ight plan is simple in structure, this paper will show that it is inherently ambiguous and will explore these issues in detail. In e ect, we propose that a rigorous semantics for ight plans can be developed and this will serve as an important stepping stone towards trajectory-based operations in the National Airspace System.

  5. Interaction of clothing and body mass index affects validity of air displacement plethysmography in adults

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: Examine the effect of alternate clothing schemes on validity of Bod Pod to estimate percent body fat (BF) compared to dual x-ray absorptiometry (DXA), and determine if these effects differ by body mass index (BMI). Design: Cross-sectional Subjects: 132 healthy adults aged 19-81 classifi...

  6. Optimum Three Impulse Trajectory Generator with Patched Conic Trajectory Model

    NASA Technical Reports Server (NTRS)

    Payne, M. H.; Pines, S.; Horsewood, J. L.

    1972-01-01

    Optimal multi-impulse trajectories were investigated as a nominal about which asymptotic expansion was used to obtain approximations of optimal low thrust trajectories. The work consisted of the analysis and description of an optimal 3-impulse trajectory program. A patched-conic trajectory model was specifically designed for compatibility with the subsequent addition of the low thrust expansion approximation.

  7. A Formally Verified Conflict Detection Algorithm for Polynomial Trajectories

    NASA Technical Reports Server (NTRS)

    Narkawicz, Anthony; Munoz, Cesar

    2015-01-01

    In air traffic management, conflict detection algorithms are used to determine whether or not aircraft are predicted to lose horizontal and vertical separation minima within a time interval assuming a trajectory model. In the case of linear trajectories, conflict detection algorithms have been proposed that are both sound, i.e., they detect all conflicts, and complete, i.e., they do not present false alarms. In general, for arbitrary nonlinear trajectory models, it is possible to define detection algorithms that are either sound or complete, but not both. This paper considers the case of nonlinear aircraft trajectory models based on polynomial functions. In particular, it proposes a conflict detection algorithm that precisely determines whether, given a lookahead time, two aircraft flying polynomial trajectories are in conflict. That is, it has been formally verified that, assuming that the aircraft trajectories are modeled as polynomial functions, the proposed algorithm is both sound and complete.

  8. Determination of cooling air mass flow for a horizontally-opposed aircraft engine installation

    NASA Technical Reports Server (NTRS)

    Miley, S. J.; Cross, E. J., Jr.; Ghomi, N. A.; Bridges, P. D.

    1979-01-01

    The relationship between the amount of cooling air flow and the corresponding flow pressure difference across an aircraft engine was investigated in flight and on the ground. The flight test results were consistent with theory, but indicated a significant installation leakage problem. A ground test blower system was used to identify and reduce the leakage. The correlation between ground test cell determined engine orifice characteristics and flight measurements showed good agreement if the engine pressure difference was based on total pressure rather than static pressure.

  9. Numerical simulation for the influence of laser-induced plasmas addition on air mass capture of hypersonic inlet

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Dou, Zhiguo; Li, Qian

    2012-03-01

    The theory of laser-induced plasmas addition to hypersonic airflow off a vehicle to increase air mass capture and improve the performance of hypersonic inlets at Mach numbers below the design value is explored. For hypersonic vehicles, when flying at mach numbers lower than the design one, we can increase the mass capture ratio of inlet through laser-induced plasmas injection to the hypersonic flow upstream of cowl lip to form a virtual cowl. Based on the theory, the model of interaction between laser-induced plasmas and hypersonic flow was established. The influence on the effect of increasing mass capture ratio was studied at different positions of laser-induced plasmas region for the external compression hypersonic inlet at Mach 5 while the design value is 6, the power of plasmas was in the range of 1-8mJ. The main results are as follows: 1. the best location of the plasma addition region is near the intersection of the nose shock of the vehicle with the continuation of the cowl line, and slightly below that line. In that case, the shock generated by the heating is close to the shock that is a reflection of the vehicle nose shock off the imaginary solid surface-extension of the cowl. 2. Plasma addition does increase mass capture, and the effect becomes stronger as more energy is added, the peak value appeared when the power of plasma was about 4mJ, when the plasma energy continues to get stronger, the mass capture will decline slowly.

  10. Obesity status trajectory groups among elementary school children

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little is known about patterns in the transition from healthy weight to overweight or obesity during the elementary school years. This study examined whether there were distinct body mass index (BMI) trajectory groups among elementary school children, and predictors of trajectory group membership. T...

  11. Departure Trajectory Synthesis and the Intercept Problem

    NASA Technical Reports Server (NTRS)

    Bolender, Michael A.; Slater, G. L.

    1997-01-01

    Two areas of the departure problem in air traffic control are discussed. The first topic is the generation of climb-out trajectories to a fix. The trajectories would be utilized by a scheduling algorithm to allocate runways, sequence the proposed departures, and assign a departure time. The second area is concerned with finding horizontal trajectories to merge aircraft from the TRACON to an open slot in the en-route environment. Solutions are presented for the intercept problem for two cases: (1) the aircraft is traveling at the speed of the aircraft in the jetway; (2) the merging aircraft has to accelerate to reach the speed of the aircraft in the en-route stream. An algorithm is given regarding the computation of a solution for the latter case. For the former, a set of equations is given that allows us to numerically solve for the coordinate where the merge will occur.

  12. Air-sea fluxes and satellite-based estimation of water masses formation

    NASA Astrophysics Data System (ADS)

    Sabia, Roberto; Klockmann, Marlene; Fernandez-Prieto, Diego; Donlon, Craig

    2015-04-01

    Recent work linking satellite-based measurements of sea surface salinity (SSS) and sea surface temperature (SST) with traditional physical oceanography has demonstrated the capability of generating routinely satellite-derived surface T-S diagrams [1] and analyze the distribution/dynamics of SSS and its relative surface density with respect to in-situ measurements. Even more recently [2,3], this framework has been extended by exploiting these T-S diagrams as a diagnostic tool to derive water masses formation rates and areas. A water mass describes a water body with physical properties distinct from the surrounding water, formed at the ocean surface under specific conditions which determine its temperature and salinity. The SST and SSS (and thus also density) at the ocean surface are largely determined by fluxes of heat and freshwater. The surface density flux is a function of the latter two and describes the change of the density of seawater at the surface. To obtain observations of water mass formation is of great interest, since they serve as indirect observations of the thermo-haline circulation. The SSS data which has become available through the SMOS [4] and Aquarius [5] satellite missions will provide the possibility of studying also the effect of temporally-varying SSS fields on water mass formation. In the present study, the formation of water masses as a function of SST and SSS is derived from the surface density flux by integrating the latter over a specific area and time period in bins of SST and SSS and then taking the derivative of the total density flux with respect to density. This study presents a test case using SMOS SSS, OSTIA SST, as well as Argo ISAS SST and SSS for comparison, heat fluxes from the NOCS Surface Flux Data Set v2.0, OAFlux evaporation and CMORPH precipitation. The study area, initially referred to the North Atlantic, is extended over two additional ocean basins and the study period covers the 2011-2012 timeframe. Yearly, seasonal

  13. Influence of dissolved humic substances on the mass transfer of organic compounds across the air-water interface.

    PubMed

    Ramus, Ksenia; Kopinke, Frank-Dieter; Georgi, Anett

    2012-01-01

    The effect of dissolved humic substances (DHS) on the rate of water-gas exchange of two volatile organic compounds was studied under various conditions of agitation intensity, solution pH and ionic strength. Mass-transfer coefficients were determined from the rate of depletion of model compounds from an apparatus containing a stirred aqueous solution with continuous purging of the headspace above the solution (dynamic system). Under these conditions, the overall transfer rate is controlled by the mass-transfer resistance on the water side of the water-gas interface. The experimental results show that the presence of DHS hinders the transport of the organic molecules from the water into the gas phase under all investigated conditions. Mass-transfer coefficients were significantly reduced even by low, environmentally relevant concentrations of DHS. The retardation effect increased with increasing DHS concentration. The magnitude of the retardation effect on water-gas exchange was compared for Suwannee River fulvic and humic acids, a commercially available leonardite humic acid and two synthetic surfactants. The observed results are in accordance with the concept of hydrodynamic effects. Surface pressure forces due to surface film formation change the hydrodynamic characteristics of water motion at the water-air interface and thus impede surface renewal.

  14. Uncertainties in Modelling Glacier Melt and Mass Balances: the Role of Air Temperature Extrapolation and Type of Melt Models

    NASA Astrophysics Data System (ADS)

    Pellicciotti, F.; Ragettli, S.; Carenzo, M.; Ayala, A.; McPhee, J. P.; Stoffel, M.

    2014-12-01

    While glacier responses to climate are understood in general terms and in their main trends, model based projections are affected by the type of model used and uncertainties in the meteorological input data, among others. Recent works have attempted at improving glacio-hydrological models by including neglected processes and investigating uncertainties in their outputs. In this work, we select two knowledge gaps in current modelling practices and illustrate their importance through modelling with a fully distributed mass balance model that includes some of the state of the art approaches for calculations of glacier ablation, accumulation and glacier geometry changes. We use an advanced mass balance model applied to glaciers in the Andes of Chile, Swiss Alps and Nepalese Himalaya to investigate two issues that seem of importance for a sound assessment of glacier changes: 1) the use of physically-based models of glacier ablation (energy balance) versus more empirical models (enhanced temperature index approaches); 2) the importance of the correct extrapolation of air temperature forcing on glaciers and the large uncertainty in model outputs associated with it. The ablation models are calibrated with a large amount of data from in-situ campaigns, and distributed observations of air temperature used to calculate lapse rates and calibrate a thermodynamic model of temperature distribution. We show that no final assessment can be made of what type of melt model is more appropriate or accurate for simulation of glacier ablation at the glacier scale, not even for relatively well studied glaciers. Both models perform in a similar manner at low elevations, but important differences are evident at high elevations, where lack of data prevents a final statement on which model better represent the actual ablation amounts. Accurate characterization of air temperature is important for correct simulations of glacier mass balance and volume changes. Substantial differences are

  15. What is the role of wind pumping on heat and mass transfer rates at the air-snow interface?

    NASA Astrophysics Data System (ADS)

    Helgason, W.; Pomeroy, J. W.

    2010-12-01

    Accurate prediction of the turbulent exchange of sensible heat and water vapour between the atmosphere and snowpack remains a challenging task under all but the most ideal conditions. Heat and mass transfer coefficients that recognize the unique properties of the snow surface are warranted. A particular area requiring improvement concerns the role of the porous nature of snow which provides a large surface area for heat and mass exchange with the atmosphere. Wind-pumping has long been considered as a viable mechanism for incorporating aerosols into snowpacks; however these processes are not considered in parameterization schemes for heat and mass transfer near the surface. This study attempts to determine the degree to which wind pumping can increase the rates of heat and mass transfer to snow, and to ascertain which structural properties of the snowpack are needed for inclusion in heat and mass transfer coefficients that reflect wind pumping processes. Based upon a review of recent geophysical and engineering literature where porous surfaces are exploited for their ability to augment heat and mass transfer rates, a technical analysis was conducted. Numerous conceptual mechanisms of wind pumping were considered: topographically-induced flow; barometric pressure changes; high frequency pressure fluctuations at the surface; and steady flow in the interfacial region. A sensitivity analysis was performed, subjecting each conceptual model to varying thermal and hydraulic conditions at the air-snow interface, as well as variable micro-structural properties of snow. It is shown that the rate of heat and mass exchange is most sensitive to the interfacial thermal conditions and factors controlling the energy balance of the uppermost snow grains. The effect upon the thermal regime of the snowpack was found to be most significant for mechanisms of wind pumping that result in shorter flow paths near the surface, rather than those caused by low frequency pressure changes. In

  16. Handling Trajectory Uncertainties for Airborne Conflict Management

    NASA Technical Reports Server (NTRS)

    Barhydt, Richard; Doble, Nathan A.; Karr, David; Palmer, Michael T.

    2005-01-01

    Airborne conflict management is an enabling capability for NASA's Distributed Air-Ground Traffic Management (DAG-TM) concept. DAGTM has the goal of significantly increasing capacity within the National Airspace System, while maintaining or improving safety. Under DAG-TM, autonomous aircraft maintain separation from each other and from managed aircraft unequipped for autonomous flight. NASA Langley Research Center has developed the Autonomous Operations Planner (AOP), an onboard decision support system that provides airborne conflict management (ACM) and strategic flight planning support for autonomous aircraft pilots. The AOP performs conflict detection, prevention, and resolution from nearby traffic aircraft and area hazards. Traffic trajectory information is assumed to be provided by Automatic Dependent Surveillance Broadcast (ADS-B). Reliable trajectory prediction is a key capability for providing effective ACM functions. Trajectory uncertainties due to environmental effects, differences in aircraft systems and performance, and unknown intent information lead to prediction errors that can adversely affect AOP performance. To accommodate these uncertainties, the AOP has been enhanced to create cross-track, vertical, and along-track buffers along the predicted trajectories of both ownship and traffic aircraft. These buffers will be structured based on prediction errors noted from previous simulations such as a recent Joint Experiment between NASA Ames and Langley Research Centers and from other outside studies. Currently defined ADS-B parameters related to navigation capability, trajectory type, and path conformance will be used to support the algorithms that generate the buffers.

  17. Computational methods for reentry trajectories

    NASA Astrophysics Data System (ADS)

    Anselmo, L.; Pardini, C.

    The trajectory modeling of uncontrolled satellites close to reentry in the atmosphere is still a challenging activity. Tracking data may be sparse and not particularly accurate, the objects complicate shape and unknown attitude evolution may render quite tricky the aerodynamic computations and, last but not the least, the models used to predict the air density at the altitudes of interest, as a function of solar and geomagnetic activity, are affected by significant uncertainties. This paper presents the techniques developed and the experience matured in the field at ISTI (formerly CNUCE), specifically in support of the reentry predictions of risky space objects carried out for the Italian civil protection authorities. In these cases, an appropriate management of the intrinsic uncertainties of the problem is critical for the dissemination of the results, avoiding, as much as possible, misunderstandings and unjustified alarm.

  18. Mathematical model for estimation of meteoroid dark flight trajectory

    NASA Astrophysics Data System (ADS)

    Vinnikov, V. V.; Gritsevich, M. I.; Turchak, L. I.

    2016-10-01

    This paper is concerned with mathematical model for numerical simulation of meteoroid dynamics. The simulations of bolide ballistics are carried out via hard sphere approximation. System of differential equations for movement and heat transfer is solved in Lagrange variables via Runge-Kutta methods. The drag force of atmospheric air is computed via Henderson formula, valid for wide ranges of Reynolds and Mach numbers. The parameters of surrounding gas are obtained from standard atmosphere model. The impact pressure is computed taking into account entropy jump through bow head shockwave and consequent isentropic deceleration of the flow in the vicinity of streamlined sphere. Meteoroid fragmentation is modeled as sequential division of parent body into two parts using random weighting coefficient for parent mass. The condition for fragmentation event occur when the hemisphere-averaged value of impact pressure exceeds the threshold of relative body strength, which nonlinearly depends on ration of initial meteoroid mass to current mass of considered fragment. To compute trajectory divergence for newly-formed splinters we introduce the repulsive force, dependent on impact pressure, cross sectional areas of mutually repulsing bodies and distances between them. The set of mathematical models is implemented as the program complex. Preliminary computational results show that fragmentation altitude, terminal velocities and maximum splinter masses are in good agreement with corresponding observations and measurements.

  19. Evaluation of ionic pollutants of acid fog and rain using a factor analysis and back trajectories.

    PubMed

    Adzuhata, T; Inotsume, J; Okamura, T; Kikuchi, R; Ozeki, T; Kajikawa, M; Ogawa, N

    2001-01-01

    Fog and rain water samples were collected at the same time in the Akita Hachimantai mountain range in northern Japan from June to September in 1998 and 1999. The various ion concentrations in these samples were analyzed, and the fog droplet sizes were measured for each fog event. As the fog droplet size increased, the ion concentration decreased. The slope of log-log plots of the concentration versus the droplet size differed with the kind of ion. In order to characterize the air pollutant, moreover, these data were quantitatively analyzed by an oblique rotational factor analysis. We found that three factors were extracted as the air pollutant source: (NH4)2SO4, acids (HNO3 + H2SO4) and sea-salt. Combining the factor analysis with the 72 h back-trajectory at 850 hPa level, we found that the contribution of each factor varied with the transport pattern of air masses.

  20. Evaluation of ionic pollutants of acid fog and rain using a factor analysis and back trajectories.

    PubMed

    Adzuhata, T; Inotsume, J; Okamura, T; Kikuchi, R; Ozeki, T; Kajikawa, M; Ogawa, N

    2001-01-01

    Fog and rain water samples were collected at the same time in the Akita Hachimantai mountain range in northern Japan from June to September in 1998 and 1999. The various ion concentrations in these samples were analyzed, and the fog droplet sizes were measured for each fog event. As the fog droplet size increased, the ion concentration decreased. The slope of log-log plots of the concentration versus the droplet size differed with the kind of ion. In order to characterize the air pollutant, moreover, these data were quantitatively analyzed by an oblique rotational factor analysis. We found that three factors were extracted as the air pollutant source: (NH4)2SO4, acids (HNO3 + H2SO4) and sea-salt. Combining the factor analysis with the 72 h back-trajectory at 850 hPa level, we found that the contribution of each factor varied with the transport pattern of air masses. PMID:11993680

  1. Back-trajectory analysis of African dust outbreaks at a coastal city in southern Spain: Selection of starting heights and assessment of African and concurrent Mediterranean contributions

    NASA Astrophysics Data System (ADS)

    Cabello, M.; Orza, J. A. G.; Dueñas, C.; Liger, E.; Gordo, E.; Cañete, S.

    2016-09-01

    The present study uses a back-trajectory analysis at multiple heights for better interpretation of the impact of the African dust outbreaks in the coastal Mediterranean city of Málaga (Spain), the southernmost large city in Europe. Throughout a 3-year period, 363 days were identified as dusty days by atmospheric transport models. During these events, PM10, SO2, O3, temperature, AOD and Ångström exponent showed statistically significant differences compared to days with no African dust. It was found that under African dust events, the study site was influenced by Mediterranean air masses at the lowermost heights and by Atlantic advections at high altitudes, while African air masses mostly reached Málaga at intermediate levels. Specifically, the lowest heights at which air masses reached the study site after having resided over Africa are confined into the 1000-2000 m range. The decoupling between the lowest heights and the ones for dust transport may explain the presence of aged air masses at the time of the African outbreak. Additionally, with the aim of studying the influence of the air mass origin and history on air quality, a new procedure based on Principal component analysis (PCA) is proposed to determine which altitudes are best suited as starting points for back-trajectory calculations, as they maximize the differences in residence time over different areas. Its application to Málaga identifies three altitudes (750, 2250 and 4500 m) and a subsequent analysis of back-trajectories for African dust days provided the main source areas over Africa as well as further insight on the Mediterranean contribution.

  2. Brief Communication: Upper-air relaxation in RACMO2 significantly improves modelled interannual surface mass balance variability in Antarctica

    NASA Astrophysics Data System (ADS)

    van de Berg, Willem Jan; Medley, Brooke

    2016-03-01

    The Regional Atmospheric Climate Model (RACMO2) has been a powerful tool for improving surface mass balance (SMB) estimates from GCMs or reanalyses. However, new yearly SMB observations for West Antarctica show that the modelled interannual variability in SMB is poorly simulated by RACMO2, in contrast to ERA-Interim, which resolves this variability well. In an attempt to remedy RACMO2 performance, we included additional upper-air relaxation (UAR) in RACMO2. With UAR, the correlation to observations is similar for RACMO2 and ERA-Interim. The spatial SMB patterns and ice-sheet-integrated SMB modelled using UAR remain very similar to the estimates of RACMO2 without UAR. We only observe an upstream smoothing of precipitation in regions with very steep topography like the Antarctic Peninsula. We conclude that UAR is a useful improvement for regional climate model simulations, although results in regions with steep topography should be treated with care.

  3. 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).

  4. Calculation of Electron Trajectories

    1982-06-01

    EGUN, the SLAC Electron Trajectory Program, computes trajectories of charged particles in electrostatic and magnetostatic focusing systems including the effects of space charge and self-magnetic fields. Starting options include Child''s Law conditions on cathodes of various shapes, user-specified initial conditions for each ray, and a combination of Child''s Law conditions and user specifications. Either rectangular or cylindrically symmetric geometry may be used. Magnetic fields may be specified using arbitrary configuration of coils, or the outputmore » of a magnet program, such as Poisson, or by an externally calculated array of the axial fields.« less

  5. The fastest evolutionary trajectory

    PubMed Central

    Traulsen, Arne; Iwasa, Yoh; Nowak, Martin A.

    2008-01-01

    Given two mutants, A and B, separated by n mutational steps, what is the evolutionary trajectory which allows a homogeneous population of A to reach B in the shortest time? We show that the optimum evolutionary trajectory (fitness landscape) has the property that the relative fitness increase between any two consecutive steps is constant. Hence, the optimum fitness landscape between A and B is given by an exponential function. Our result is precise for small mutation rates and excluding back mutations. We discuss deviations for large mutation rates and including back mutations. For very large mutation rates, the optimum fitness landscape is flat and has a single peak at type B. PMID:17900629

  6. Development of portable mass spectrometer with electron cyclotron resonance ion source for detection of chemical warfare agents in air.

    PubMed

    Urabe, Tatsuya; Takahashi, Kazuya; Kitagawa, Michiko; Sato, Takafumi; Kondo, Tomohide; Enomoto, Shuichi; Kidera, Masanori; Seto, Yasuo

    2014-01-01

    A portable mass spectrometer with an electron cyclotron resonance ion source (miniECRIS-MS) was developed. It was used for in situ monitoring of trace amounts of chemical warfare agents (CWAs) in atmospheric air. Instrumental construction and parameters were optimized to realize a fast response, high sensitivity, and a small body size. Three types of CWAs, i.e., phosgene, mustard gas, and hydrogen cyanide were examined to check if the mass spectrometer was able to detect characteristic elements and atomic groups. From the results, it was found that CWAs were effectively ionized in the miniECRIS-MS, and their specific signals could be discerned over the background signals of air. In phosgene, the signals of the 35Cl+ and 37Cl+ ions were clearly observed with high dose-response relationships in the parts-per-billion level, which could lead to the quantitative on-site analysis of CWAs. A parts-per-million level of mustard gas, which was far lower than its lethal dosage (LCt50), was successfully detected with a high signal-stability of the plasma ion source. It was also found that the chemical forms of CWAs ionized in the plasma, i.e., monoatomic ions, fragment ions, and molecular ions, could be detected, thereby enabling the effective identification of the target CWAs. Despite the disadvantages associated with miniaturization, the overall performance (sensitivity and response time) of the miniECRIS-MS in detecting CWAs exceeded those of sector-type ECRIS-MS, showing its potential for on-site detection in the future. PMID:24211802

  7. Development of portable mass spectrometer with electron cyclotron resonance ion source for detection of chemical warfare agents in air.

    PubMed

    Urabe, Tatsuya; Takahashi, Kazuya; Kitagawa, Michiko; Sato, Takafumi; Kondo, Tomohide; Enomoto, Shuichi; Kidera, Masanori; Seto, Yasuo

    2014-01-01

    A portable mass spectrometer with an electron cyclotron resonance ion source (miniECRIS-MS) was developed. It was used for in situ monitoring of trace amounts of chemical warfare agents (CWAs) in atmospheric air. Instrumental construction and parameters were optimized to realize a fast response, high sensitivity, and a small body size. Three types of CWAs, i.e., phosgene, mustard gas, and hydrogen cyanide were examined to check if the mass spectrometer was able to detect characteristic elements and atomic groups. From the results, it was found that CWAs were effectively ionized in the miniECRIS-MS, and their specific signals could be discerned over the background signals of air. In phosgene, the signals of the 35Cl+ and 37Cl+ ions were clearly observed with high dose-response relationships in the parts-per-billion level, which could lead to the quantitative on-site analysis of CWAs. A parts-per-million level of mustard gas, which was far lower than its lethal dosage (LCt50), was successfully detected with a high signal-stability of the plasma ion source. It was also found that the chemical forms of CWAs ionized in the plasma, i.e., monoatomic ions, fragment ions, and molecular ions, could be detected, thereby enabling the effective identification of the target CWAs. Despite the disadvantages associated with miniaturization, the overall performance (sensitivity and response time) of the miniECRIS-MS in detecting CWAs exceeded those of sector-type ECRIS-MS, showing its potential for on-site detection in the future.

  8. A mass balance method for non-intrusive measurements of surface-air trace gas exchange

    NASA Astrophysics Data System (ADS)

    Denmead, O. T.; Harper, L. A.; Freney, J. R.; Griffith, D. W. T.; Leuning, R.; Sharpe, R. R.

    A mass balance method is described for calculating gas production from a surface or volume source in a small test plot from measurements of differences in the horizontal fluxes of the gas across upwind and downwind boundaries. It employs a square plot, 24 m×24 m, with measurements of gas concentration at four heights (up to 3.5 m) along each of the four boundaries. Gas concentrations are multiplied by the appropriate vector winds to yield the horizontal fluxes at each height on each boundary. The difference between these fluxes integrated over downwind and upwind boundaries represents production. Illustrations of the method, which involve exchanges of methane and carbon dioxide, are drawn from experiments with landfills, pastures and grazing animals. Tests included calculation of recovery rates from known gas releases and comparisons with a conventional micrometeorological approach and a backward dispersion model. The method performed satisfactorily in all cases. Its sensitivity for measuring exchanges of CO 2, CH 4 and N 2O in various scenarios was examined. As employed by us, the mass balance method can suffer from errors arising from the large number of gas analyses required for a flux determination, and becomes unreliable when there are light winds and variable wind directions. On the other hand, it is non-disturbing, has a simple theoretical basis, is independent of atmospheric stability or the shape of the wind profile, and is appropriate for flux measurement in situations where conventional micrometeorological methods can not be used, e.g. for small plots, elevated point sources, and heterogeneous surface sources.

  9. Selected Ion Flow-Drift Tube Mass Spectrometry: Quantification of Volatile Compounds in Air and Breath.

    PubMed

    Spesyvyi, Anatolii; Smith, David; Španěl, Patrik

    2015-12-15

    A selected ion flow-drift tube mass spectrometric analytical technique, SIFDT-MS, is described that extends the established selected ion flow tube mass spectrometry, SIFT-MS, by the inclusion of a static but variable E-field along the axis of the flow tube reactor in which the analytical ion-molecule chemistry occurs. The ion axial speed is increased in proportion to the reduced field strength E/N (N is the carrier gas number density), and the residence/reaction time, t, which is measured by Hadamard transform multiplexing, is correspondingly reduced. To ensure a proper understanding of the physics and ion chemistry underlying SIFDT-MS, ion diffusive loss to the walls of the flow-drift tube and the mobility of injected H3O(+) ions have been studied as a function of E/N. It is seen that the derived diffusion coefficient and mobility of H3O(+) ions are consistent with those previously reported. The rate coefficient has been determined at elevated E/N for the association reaction of the H3O(+) reagent ions with H2O molecules, which is the first step in the production of H3O(+)(H2O)1,2,3 reagent hydrate ions. The production of hydrated analyte ion was also experimentally investigated. The analytical performance of SIFDT-MS is demonstrated by the quantification of acetone and isoprene in exhaled breath. Finally, the essential features of SIFDT-MS and SIFT-MS are compared, notably pointing out that a much lower speed of the flow-drive pump is required for SIFDT-MS, which facilitates the development of smaller cost-effective analytical instruments for real time breath and fluid headspace analyses.

  10. Selected Ion Flow-Drift Tube Mass Spectrometry: Quantification of Volatile Compounds in Air and Breath.

    PubMed

    Spesyvyi, Anatolii; Smith, David; Španěl, Patrik

    2015-12-15

    A selected ion flow-drift tube mass spectrometric analytical technique, SIFDT-MS, is described that extends the established selected ion flow tube mass spectrometry, SIFT-MS, by the inclusion of a static but variable E-field along the axis of the flow tube reactor in which the analytical ion-molecule chemistry occurs. The ion axial speed is increased in proportion to the reduced field strength E/N (N is the carrier gas number density), and the residence/reaction time, t, which is measured by Hadamard transform multiplexing, is correspondingly reduced. To ensure a proper understanding of the physics and ion chemistry underlying SIFDT-MS, ion diffusive loss to the walls of the flow-drift tube and the mobility of injected H3O(+) ions have been studied as a function of E/N. It is seen that the derived diffusion coefficient and mobility of H3O(+) ions are consistent with those previously reported. The rate coefficient has been determined at elevated E/N for the association reaction of the H3O(+) reagent ions with H2O molecules, which is the first step in the production of H3O(+)(H2O)1,2,3 reagent hydrate ions. The production of hydrated analyte ion was also experimentally investigated. The analytical performance of SIFDT-MS is demonstrated by the quantification of acetone and isoprene in exhaled breath. Finally, the essential features of SIFDT-MS and SIFT-MS are compared, notably pointing out that a much lower speed of the flow-drive pump is required for SIFDT-MS, which facilitates the development of smaller cost-effective analytical instruments for real time breath and fluid headspace analyses. PMID:26583448

  11. Evaluation of chemical transport model predictions of primary organic aerosol for air masses classified by particle component-based factor analysis

    NASA Astrophysics Data System (ADS)

    Stroud, C. A.; Moran, M. D.; Makar, P. A.; Gong, S.; Gong, W.; Zhang, J.; Slowik, J. G.; Abbatt, J. P. D.; Lu, G.; Brook, J. R.; Mihele, C.; Li, Q.; Sills, D.; Strawbridge, K. B.; McGuire, M. L.; Evans, G. J.

    2012-09-01

    Observations from the 2007 Border Air Quality and Meteorology Study (BAQS-Met 2007) in Southern Ontario, Canada, were used to evaluate predictions of primary organic aerosol (POA) and two other carbonaceous species, black carbon (BC) and carbon monoxide (CO), made for this summertime period by Environment Canada's AURAMS regional chemical transport model. Particle component-based factor analysis was applied to aerosol mass spectrometer measurements made at one urban site (Windsor, ON) and two rural sites (Harrow and Bear Creek, ON) to derive hydrocarbon-like organic aerosol (HOA) factors. A novel diagnostic model evaluation was performed by investigating model POA bias as a function of HOA mass concentration and indicator ratios (e.g. BC/HOA). Eight case studies were selected based on factor analysis and back trajectories to help classify model bias for certain POA source types. By considering model POA bias in relation to co-located BC and CO biases, a plausible story is developed that explains the model biases for all three species. At the rural sites, daytime mean PM1 POA mass concentrations were under-predicted compared to observed HOA concentrations. POA under-predictions were accentuated when the transport arriving at the rural sites was from the Detroit/Windsor urban complex and for short-term periods of biomass burning influence. Interestingly, the daytime CO concentrations were only slightly under-predicted at both rural sites, whereas CO was over-predicted at the urban Windsor site with a normalized mean bias of 134%, while good agreement was observed at Windsor for the comparison of daytime PM1 POA and HOA mean values, 1.1 μg m-3 and 1.2 μg m-3, respectively. Biases in model POA predictions also trended from positive to negative with increasing HOA values. Periods of POA over-prediction were most evident at the urban site on calm nights due to an overly-stable model surface layer. This model behaviour can be explained by a combination of model under

  12. Association between indoor air pollutant exposure and blood pressure and heart rate in subjects according to body mass index.

    PubMed

    Jung, Chien-Cheng; Su, Huey-Jen; Liang, Hsiu-Hao

    2016-01-01

    This study investigates the effects of high body mass index (BMI) of subjects on individual who exhibited high cardiovascular disease indexes with blood pressure (BP) and heart rate (HR) when exposed to high levels of indoor air pollutants. We collected 115 office workers, and measured their systolic blood pressure (SBP), diastolic blood pressure (DBP) and HR at the end of the workday. The subjects were divided into three groups according to BMI: 18-24 (normal weight), 24-27 (overweight) and >27 (obese). This study also measured the levels of carbon dioxide (CO2), total volatile organic compounds (TVOC), particulate matter with an aerodynamic diameter less than 2.5μm (PM2.5), as well as the bacteria and fungi in the subjects' work-places. The pollutant effects were divided by median. Two-way analysis of variance (ANOVA) was used to analyze the health effects of indoor air pollution exposure according to BMI. Our study showed that higher levels of SBP, DBP and HR occurred in subjects who were overweight or obese as compared to those with normal weight. Moreover, there was higher level of SBP in subjects who were overweight or obese when they were exposed to higher levels of TVOC and fungi (p<0.05). We also found higher value for DBP and HR with increasing BMI to be associated with exposure to higher TVOC levels. This study suggests that individuals with higher BMI have higher cardiovascular disease risk when they are exposed to poor indoor air quality (IAQ), and specifically in terms of TVOC.

  13. Air flow-assisted ionization imaging mass spectrometry method for easy whole-body molecular imaging under ambient conditions.

    PubMed

    Luo, Zhigang; He, Jiuming; Chen, Yi; He, Jingjing; Gong, Tao; Tang, Fei; Wang, Xiaohao; Zhang, Ruiping; Huang, Lan; Zhang, Lianfeng; Lv, Haining; Ma, Shuanggang; Fu, Zhaodi; Chen, Xiaoguang; Yu, Shishan; Abliz, Zeper

    2013-03-01

    Whole-body molecular imaging is able to directly map spatial distribution of molecules and monitor its biotransformation in intact biological tissue sections. Imaging mass spectrometry (IMS), a label-free molecular imaging method, can be used to image multiple molecules in a single measurement with high specificity. Herein, a novel easy-to-implement, whole-body IMS method was developed with air flow-assisted ionization in a desorption electrospray ionization mode. The developed IMS method can effectively image molecules in a large whole-body section in open air without sample pretreatment, such as chemical labeling, section division, or matrix deposition. Moreover, the signal levels were improved, and the spatial assignment errors were eliminated; thus, high-quality whole-body images were obtained. With this novel IMS method, in situ mapping analysis of molecules was performed in adult rat sections with picomolar sensitivity under ambient conditions, and the dynamic information of molecule distribution and its biotransformation was provided to uncover molecular events at the whole-animal level. A global view of the differential distribution of an anticancer agent and its metabolites was simultaneously acquired in whole-body rat and model mouse bearing neuroglioma along the administration time. The obtained drug distribution provided rich information for identifying the targeted organs and predicting possible tumor spectrum, pharmacological activity, and potential toxicity of drug candidates.

  14. Development of analysis of volatile polyfluorinated alkyl substances in indoor air using thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Wu, Yaoxing; Chang, Victor W-C

    2012-05-18

    The study attempts to utilize thermal desorption (TD) coupled with gas chromatography-mass spectrometry (GC-MS) for determination of indoor airborne volatile polyfluorinated alkyl substances (PFASs), including four fluorinated alcohols (FTOHs), two fluorooctane sulfonamides (FOSAs), and two fluorooctane sulfonamidoethanols (FOSEs). Standard stainless steel tubes of Tenax/Carbograph 1 TD were employed for low-volume sampling and exhibited minimal breakthrough of target analytes in sample collection. The method recoveries were in the range of 88-119% for FTOHs, 86-138% for FOSAs, exhibiting significant improvement compared with other existing air sampling methods. However, the widely reported high method recoveries of FOSEs were also observed (139-210%), which was probably due to the structural differences between FOSEs and internal standards. Method detection limit, repeatability, linearity, and accuracy were reported as well. The approach has been successfully applied to routine quantification of targeted PFASs in indoor environment of Singapore. The significantly shorter sampling time enabled the observation of variations of concentrations of targeted PFASs within different periods of a day, with higher concentration levels at night while ventilation systems were shut off. This indicated the existence of indoor sources and the importance of building ventilation and air conditioning system.

  15. Identification of water-soluble polar organics in air and vehicular emitted particulate matter using ultrahigh resolution mass spectrometry and Capillary electrophoresis - mass spectrometry.

    NASA Astrophysics Data System (ADS)

    Schmitt-Kopplin, P.; Yassine, M.; Gebefugi, I.; Hertkorn, N.; Dabek-Zlotorzynska, E.

    2009-04-01

    The effects of aerosols on human health, atmospheric chemistry, and climate are among the central topics in current environmental health research. Detailed and accurate measurements of the chemical composition of air particulate matter (PM) represent a challenging analytical task. Minute sample amounts are usually composed of several main constituents and hundreds of minor and trace constituents. Moreover, the composition of individual particles can be fairly uniform or very different (internally or externally mixed aerosols), depending on their origin and atmospheric aging processes (coagulation, condensation / evaporation, chemical reaction). The aim of the presentation was the characterization of the organic matter (OM) fraction of environmental aerosols which is not accessible by GC-methods, either because of their high molecular weight, their polarity or due to thermal instability. We also describe the main chemical characteristics of complexe oligomeric organic fraction extracted from different aerosols collected in urban and rural area in Germany and Canada. Mass spectrometry (MS) became an essential tool used by many prominent leaders of the biological research community and the importance of MS to the future of biological research is now clearly evident as in the fields of Proteomics and Metabolomics. Especially Fourier Transform Ion Cyclotron Mass Spectrometry (ICR-FT/MS) is an ultrahigh resolution MS that allows new approach in the analysis of complex mixtures. The mass resolution (< 200 ppb) allowed assigning the elemental composition (C, H, O, N, S…) to each of the obtained mass peaks and thus already a description of the mixture in terms of molecular composition. This possibility is used by the authors together with a high resolution separation method of charged compounds: capillary electrophoresis. A CE-ESI-MS method using an ammonium acetate based background electrolyte (pH 4.7) was developed for the determination of isomeric benzoic acids in

  16. The influence of air temperature inversions on snowmelt and glacier mass-balance simulations, Ammassalik island, SE Greenland

    SciTech Connect

    Mernild, Sebastian Haugard; Liston, Glen

    2009-01-01

    In many applications, a realistic description of air temperature inversions is essential for accurate snow and glacier ice melt, and glacier mass-balance simulations. A physically based snow-evolution modeling system (SnowModel) was used to simulate eight years (1998/99 to 2005/06) of snow accumulation and snow and glacier ice ablation from numerous small coastal marginal glaciers on the SW-part of Ammassalik Island in SE Greenland. These glaciers are regularly influenced by inversions and sea breezes associated with the adjacent relatively low temperature and frequently ice-choked fjords and ocean. To account for the influence of these inversions on the spatiotemporal variation of air temperature and snow and glacier melt rates, temperature inversion routines were added to MircoMet, the meteorological distribution sub-model used in SnowModel. The inversions were observed and modeled to occur during 84% of the simulation period. Modeled inversions were defined not to occur during days with strong winds and high precipitation rates due to the potential of inversion break-up. Field observations showed inversions to extend from sea level to approximately 300 m a.s.l., and this inversion level was prescribed in the model simulations. Simulations with and without the inversion routines were compared. The inversion model produced air temperature distributions with warmer lower elevation areas and cooler higher elevation areas than without inversion routines due to the use of cold sea-breeze base temperature data from underneath the inversion. This yielded an up to 2 weeks earlier snowmelt in the lower areas and up to 1 to 3 weeks later snowmelt in the higher elevation areas of the simulation domain. Averaged mean annual modeled surface mass-balance for all glaciers (mainly located above the inversion layer) was -720 {+-} 620 mm w.eq. y{sup -1} for inversion simulations, and -880 {+-} 620 mm w.eq. y{sup -1} without the inversion routines, a difference of 160 mm w.eq. y

  17. First day of an oil spill on the open sea: early mass transfers of hydrocarbons to air and water.

    PubMed

    Gros, Jonas; Nabi, Deedar; Würz, Birgit; Wick, Lukas Y; Brussaard, Corina P D; Huisman, Johannes; van der Meer, Jan R; Reddy, Christopher M; Arey, J Samuel

    2014-08-19

    During the first hours after release of petroleum at sea, crude oil hydrocarbons partition rapidly into air and water. However, limited information is available about very early evaporation and dissolution processes. We report on the composition of the oil slick during the first day after a permitted, unrestrained 4.3 m(3) oil release conducted on the North Sea. Rapid mass transfers of volatile and soluble hydrocarbons were observed, with >50% of ≤C17 hydrocarbons disappearing within 25 h from this oil slick of <10 km(2) area and <10 μm thickness. For oil sheen, >50% losses of ≤C16 hydrocarbons were observed after 1 h. We developed a mass transfer model to describe the evolution of oil slick chemical composition and water column hydrocarbon concentrations. The model was parametrized based on environmental conditions and hydrocarbon partitioning properties estimated from comprehensive two-dimensional gas chromatography (GC×GC) retention data. The model correctly predicted the observed fractionation of petroleum hydrocarbons in the oil slick resulting from evaporation and dissolution. This is the first report on the broad-spectrum compositional changes in oil during the first day of a spill at the sea surface. Expected outcomes under other environmental conditions are discussed, as well as comparisons to other models.

  18. Patched Conic Trajectory Code

    NASA Technical Reports Server (NTRS)

    Park, Brooke Anderson; Wright, Henry

    2012-01-01

    PatCon code was developed to help mission designers run trade studies on launch and arrival times for any given planet. Initially developed in Fortran, the required inputs included launch date, arrival date, and other orbital parameters of the launch planet and arrival planets at the given dates. These parameters include the position of the planets, the eccentricity, semi-major axes, argument of periapsis, ascending node, and inclination of the planets. With these inputs, a patched conic approximation is used to determine the trajectory. The patched conic approximation divides the planetary mission into three parts: (1) the departure phase, in which the two relevant bodies are Earth and the spacecraft, and where the trajectory is a departure hyperbola with Earth at the focus; (2) the cruise phase, in which the two bodies are the Sun and the spacecraft, and where the trajectory is a transfer ellipse with the Sun at the focus; and (3) the arrival phase, in which the two bodies are the target planet and the spacecraft, where the trajectory is an arrival hyperbola with the planet as the focus.

  19. Mission objectives and trajectories

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The present state of the knowledge of asteroids was assessed to identify mission and target priorities for planning asteroidal flights in the 1980's and beyond. Mission objectives, mission analysis, trajectory studies, and cost analysis are discussed. A bibliography of reports and technical memoranda is included.

  20. Trajectory structures and transport

    SciTech Connect

    Vlad, Madalina; Spineanu, Florin

    2004-11-01

    The special problem of transport in two-dimensional divergence-free stochastic velocity fields is studied by developing a statistical approach, the nested subensemble method. The nonlinear process of trapping determined by such fields generates trajectory structures whose statistical characteristics are determined. These structures strongly influence the transport.

  1. Cyclic organic peroxides identification and trace analysis by Raman microscopy and open-air chemical ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Pena-Quevedo, Alvaro Javier

    The persistent use of cyclic organic peroxides in explosive devices has increased the interest in study these compounds. Development of methodologies for the detection of triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) has become an urgent priority. However, differences in physical properties between cyclic organic peroxides make difficult the development of a general method for peroxide analysis and detection. Following this urgency, the first general technique for the analysis of any peroxide, regarding its structural differences is reported. Characterization and detection of TATP and HMTD was performed using an Open-Air Chemical Ionization High-Resolution Time-of-Flight Mass Spectrometer. The first spectrometric analysis for tetramethylene diperoxide dicarbamide (TMDD) and other nitrogen based peroxides using Raman Microscopy and Mass Spectrometry is reported. Analysis of cyclic peroxides by GC-MS was also conducted to compare results with OACI-HRTOF data. In the OACI mass spectrum, HMTD showed a clear signal at m/z 209 MH + and a small adduct peak at m/z 226 [M+NH4]+ that allowed its detection in commercial standard solutions and lab made standards. TMDD presented a molecular peak of m/z 237 MH+ and an adduct peak of m/z 254 [M+NH4]+. TATP showed a single peak at m/z 240 [M+NH4]+, while the peak of m/z 223 or 222 was completely absent. This evidence suggests that triperoxides are stabilized by the ammonium ion. TATP samples with deuterium enrichment were analyzed to compare results that could differentiate from HMTD. Raman microscopy was used as a complementary characterization method and was an essential tool for cyclic peroxides identification, particularly for those which could not be extensively purified. All samples were characterized by Raman spectroscopy to confirm the Mass Spectrometry results. Peroxide O-O vibrations were observed around 750-970 cm-1. D18-TATP studies had identified ketone triperoxide nu(O-O) vibration around

  2. The potential of LIRIC to validate the vertical profiles of the aerosol mass concentration estimated by an air quality model

    NASA Astrophysics Data System (ADS)

    Siomos, Nikolaos; Filoglou, Maria; Poupkou, Anastasia; Liora, Natalia; Dimopoulos, Spyros; Melas, Dimitris; Chaikovsky, Anatoli; Balis, Dimitris

    2015-04-01

    Vertical profiles of the aerosol mass concentration derived by a retrieval algorithm that uses combined sunphotometer and LIDAR data (LIRIC) were used in order to validate the mass concentration profiles estimated by the air quality model CAMx. LIDAR and CIMEL measurements of the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki were used for this validation.The aerosol mass concentration profiles of the fine and coarse mode derived by CAMx were compared with the respective profiles derived by the retrieval algorithm. For the coarse mode particles, forecasts of the Saharan dust transportation model BSC-DREAM8bV2 were also taken into account. Each of the retrieval algorithm's profiles were matched to the models' profile with the best agreement within a time window of four hours before and after the central measurement. OPAC, a software than can provide optical properties of aerosol mixtures, was also employed in order to calculate the angstrom exponent and the lidar ratio values for 355nm and 532nm for each of the model's profiles aiming in a comparison with the angstrom exponent and the lidar ratio values derived by the retrieval algorithm for each measurement. The comparisons between the fine mode aerosol concentration profiles resulted in a good agreement between CAMx and the retrieval algorithm, with the vertical mean bias error never exceeding 7 μgr/m3. Concerning the aerosol coarse mode concentration profiles both CAMx and BSC-DREAM8bV2 values are severely underestimated, although, in cases of Saharan dust transportation events there is an agreement between the profiles of BSC-DREAM8bV2 model and the retrieval algorithm.

  3. Physical and chemical processes of air masses in the Aegean Sea during Etesians: Aegean-GAME airborne campaign.

    PubMed

    Tombrou, M; Bossioli, E; Kalogiros, J; Allan, J D; Bacak, A; Biskos, G; Coe, H; Dandou, A; Kouvarakis, G; Mihalopoulos, N; Percival, C J; Protonotariou, A P; Szabó-Takács, B

    2015-02-15

    High-resolution measurements of gas and aerosols' chemical composition along with meteorological and turbulence parameters were performed over the Aegean Sea (AS) during an Etesian outbreak in the framework of the Aegean-GAME airborne campaign. This study focuses on two distinct Etesian patterns, with similarities inside the Marine Atmospheric Boundary Layer (MABL) and differences at higher levels. Under long-range transport and subsidence the pollution load is enhanced (by 17% for CO, 11% for O3, 28% for sulfate, 62% for organic mass, 47% for elemental carbon), compared to the pattern with a weaker synoptic system. Sea surface temperature (SST) was a critical parameter for the MABL structure, turbulent fluxes and pollutants' distribution at lower levels. The MABL height was below 500 m asl over the eastern AS (favoring higher accumulation), and deeper over the western AS. The most abundant components of total PM1 were sulfate (40-50%) and organics (30-45%). Higher average concentrations measured over the eastern AS (131 ± 76 ppbv for CO, 62.5 ± 4.1 ppbv for O3, 5.0 ± 1.1 μg m(-3) for sulfate, 4.7 ± 0.9 μg m(-3) for organic mass and 0.5 ± 0.2 μg m(-3) for elemental carbon). Under the weaker synoptic system, cleaner but more acidic air masses prevailed over the eastern part, while distinct aerosol layers of different signature were observed over the western part. The Aitken and accumulation modes contributed equally during the long-range transport, while the Aitken modes dominated during local or medium range transport. PMID:25460953

  4. On-line analysis of volatile chlorinated hydrocarbons in air by gas chromatography-mass spectrometry Improvements in preconcentration and injection steps.

    PubMed

    Zoccolillo, Lelio; Amendola, Luca; Insogna, Susanna; Pastorini, Elisabetta

    2010-06-11

    An analytical system composed of a cryofocusing trap injector device coupled to a gas chromatograph with mass spectrometric detection (CTI-GC-MS) specific for the on-line analysis in air of volatile chlorinated hydrocarbons (VCHCs) (dichloromethane; chloroform; 1,1,1-trichloroethane; tetrachloromethane; 1,1,2-trichloroethylene; tetrachloroethylene) was developed. The cryofocusing trap injector was the result of appropriate low cost modifications to an original purge-and-trap device to make it suitable for direct air analysis even in the case of only slightly contaminated air samples, such as those from remote zones. The CTI device can rapidly and easily be rearranged into the purge-and-trap allowing water and air analysis with the same apparatus. Air samples, collected in stainless steel canisters, were introduced directly into the CTI-GC-MS system to realize cryo-concentration (at -120 degrees C), thermal desorption (at 200 degrees C) and for the subsequent analysis of volatiles. The operating phases and conditions were customised and optimized. Recovery efficiency was optimized in terms of moisture removal, cold trap temperature and sampling mass flow. The injection of entrapped volatiles was realized through a direct transfer with high chromatographic reliability (capillary column-capillary column). These improvements allowed obtaining limits of detection (LODs) at least one order of magnitude lower than current LODs for the investigated substances. The method was successfully employed on real samples: air from urban and rural areas and air from remote zones such as Antarctica.

  5. Low-thrust rocket trajectories

    SciTech Connect

    Keaton, P.W.

    1986-01-01

    The development of low-thrust propulsion systems to complement chemical propulsion systems will greatly enhance the evolution of future space programs. Two advantages of low-thrust rockets are stressed: first, in a strong gravitational field, such as occurs near the Earth, freighter missions with low-thrust engines require one-tenth as much propellant as do chemical engines. Second, in a weak gravitational field, such as occurs in the region between Venus and Mars, low-thrust rockets are faster than chemical rockets with comparable propellant mass. The purpose here is to address the physics of low-thrust trajectories and to interpret the results with two simple models. Analytic analyses are used where possible - otherwise, the results of numerical calculations are presented in graphs. The author has attempted to make this a self-contained report. 57 refs., 10 figs.

  6. Low-thrust rocket trajectories

    SciTech Connect

    Keaton, P.W.

    1987-03-01

    The development of low-thrust propulsion systems to complement chemical propulsion systems will greatly enhance the evolution of future space programs. Two advantages of low-thrust rockets are stressed: first, in a strong gravitational field, such as occurs near the Earth, freighter missions with low-thrust engines require one-tenth as much propellant as do chemical engines. Second, in a weak gravitational field, such as occurs in the region between Venus and Mars, low-thrust rockets are faster than chemical rockets with comparable propellant mass. The purpose here is to address the physics of low-thrust trajectories and to interpret the results with two simple models. Analytic analyses are used where possible - otherwise, the results of numerical calculations are presented in graphs. The author has attempted to make this a self-contained report.

  7. The Potential of The Synergy of Sunphotometer and Lidar Data to Validate Vertical Profiles of The Aerosol Mass Concentration Estimated by An Air Quality Model

    NASA Astrophysics Data System (ADS)

    Siomos, N.; Filioglou, M.; Poupkou, A.; Liora, N.; Dimopoulos, S.; Melas, D.; Chaikovsky, A.; Balis, D. S.

    2016-06-01

    Vertical profiles of the aerosol mass concentration derived by the Lidar/Radiometer Inversion Code (LIRIC), that uses combined sunphotometer and lidar data, were used in order to validate the aerosol mass concentration profiles estimated by the air quality model CAMx. Lidar and CIMEL measurements performed at the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki, Greece (40.5N, 22.9E) from the period 2013-2014 were used in this study.

  8. Rural southeast Texas air quality measurements during the 2006 Texas Air Quality Study.

    PubMed

    Schade, Gunnar W; Khan, Siraj; Park, Changhyoun; Boedeker, Ian

    2011-10-01

    The authors conducted air quality measurements of the criteria pollutants carbon monoxide, nitrogen oxides, and ozone together with meteorological measurements at a park site southeast of College Station, TX, during the 2006 Texas Air Quality Study II (TexAQS). Ozone, a primary focus of the measurements, was above 80 ppb during 3 days and above 75 ppb during additional 8 days in summer 2006, suggestive of possible violations of the ozone National Ambient Air Quality Standard (NAAQS) in this area. In concordance with other air quality measurements during the TexAQS II, elevated ozone mixing ratios coincided with northerly flows during days after cold front passages. Ozone background during these days was as high as 80 ppb, whereas southerly air flows generally provided for an ozone background lower than 40 ppb. Back trajectory analysis shows that local ozone mixing ratios can also be strongly affected by the Houston urban pollution plume, leading to late afternoon ozone increases of as high as 50 ppb above background under favorable transport conditions. The trajectory analysis also shows that ozone background increases steadily the longer a southern air mass resides over Texas after entering from the Gulf of Mexico. In light of these and other TexAQS findings, it appears that ozone air quality is affected throughout east Texas by both long-range and regional ozone transport, and that improvements therefore will require at least a regionally oriented instead of the current locally oriented ozone precursor reduction policies.

  9. PM10-bound polycyclic aromatic hydrocarbons in Chiang Mai (Thailand): Seasonal variations, source identification, health risk assessment and their relationship to air-mass movement

    NASA Astrophysics Data System (ADS)

    Wiriya, Wan; Prapamontol, Tippawan; Chantara, Somporn

    2013-04-01

    found that vehicle emission and biomass burning were the main sources of PM10 and PAHs in this area. The high ratio value of benzo(a)anthracene/chrysene (BaA/CHR) in the dry season of 2010 indicated possible photochemical processes and long distance emissions. Findings on source identification of PM10 and PAHs were found to be relevant to the direction and speed of air mass movement run by backward trajectory.

  10. Establishing cycler trajectories between Earth and Mars

    NASA Astrophysics Data System (ADS)

    Rogers, Blake A.; Hughes, Kyle M.; Longuski, James M.; Aldrin, Buzz

    2015-07-01

    Several cycler concepts have been proposed to provide safe and comfortable quarters for astronauts traveling between the Earth and Mars. However, no literature has appeared to show how these massive vehicles might be placed into their cycler trajectories. In this paper, trajectories are designed that use either V∞ leveraging or low thrust to establish cycler vehicles in their desired orbits. In the cycler trajectory cases considered, the use of V∞ leveraging or low thrust substantially reduces the total propellant needed to achieve the cycler orbit compared to direct orbit insertion. In the case of the classic Aldrin cycler, the propellant savings due to V∞ leveraging can be as large as 24 metric tons for a cycler vehicle with a dry mass of 75 metric tons, and an additional 111 metric tons by instead using low thrust. The two-synodic period cyclers considered benefit less from V∞ leveraging, but have a smaller total propellant mass due to their lower approach velocities at Earth and Mars. It turns out that, for low-thrust establishment, the propellant required is approximately the same for each of the cycler trajectories. The cycler concept may provide a crucial enabling technology that is safe, economical, and sustainable for the continuous habitation of Mars.

  11. TrackTable Trajectory Analysis

    SciTech Connect

    Wilson, Andrew T.

    2014-08-25

    Tracktable is designed for analysis and rendering of the trajectories of moving objects such as planes, trains, automobiles and ships. Its purpose is to operate on large sets of trajectories (millions) to help a user detect, analyze and display patterns. It will also be used to disseminate trajectory research results from Sandia's PANTHER Grand Challenge LDRD.

  12. Trajectory shaping rendezvous guidance

    NASA Astrophysics Data System (ADS)

    Klumpp, A. R.

    The Space Station will bring a great increase in rendezvous traffic. Formerly, rendezvous has been expensive in terms of time and crew involvement. Multiple trajectory adjustments on separate orbits have been required to meet safety, lighting, and geometry requirements. This paper describes a new guidance technique in which the approach trajectory is shaped by a sequence of velocity increments in order to satisfy multiple constraints within a single orbit. The approach phase is planned before the mission, leaving a group of free parameters that are optimized by onboard guidance. Fuel penalties are typically a few percent, compared to unshaped Hohmann transfers, and total fuel costs can be less than those of more time-consuming ways of meeting the same requirements.

  13. Hydrogen sulphide in human nasal air quantified using thermal desorption and selected ion flow tube mass spectrometry.

    PubMed

    Wondimu, Taddese; Wang, Rui; Ross, Brian

    2014-09-01

    The discovery that hydrogen sulphide (H2S) acts as a gasotransmitter when present at very low concentrations (sub-parts per billion (ppbv)) has resulted in the need to quickly quantify trace amounts of the gas in complex biological samples. Selected ion flow tube mass spectrometry (SIFT-MS) is capable of real-time quantification of H2S but many SIFT-MS instruments lack sufficient sensitivity for this application. In this study we investigate the utility of combining thermal desorption with SIFT-MS for quantifying H2S in the 0.1-1 ppbv concentration range. Human orally or nasally derived breath, and background ambient air, were collected in sampling bags and dried by passing through CaCl2 and H2S pre-concentrated using a sorbent trap optimised for the capture of this gas. The absorbed H2S was then thermally desorbed and quantified by SIFT-MS. H2S concentrations in ambient air, nasal breath and oral breath collected from 10 healthy volunteers were 0.12  ±  0.02 (mean ± SD), 0.40  ±  0.11 and 3.1  ±  2.5 ppbv respectively, and in the oral cavity H2S, quantified by SIFT-MS without pre-concentration, was present at 13.5  ±  8.6 ppbv. The oral cavity H2S correlates well with oral breath H2S but not with nasal breath H2S, suggesting that oral breath H2S derives mainly from the oral cavity but nasal breath is likely pulmonary in origin. The successful quantification of such low concentrations of H2S in nasal air using a rapid analytical procedure paves the way for the straightforward analysis of H2S in breath and may assist in elucidating the role that H2S plays in biological systems.

  14. Automated high-speed analysis of selected organic compounds in urban air by on-line isotopic dilution cryofocusing gas chromatography/mass spectrometry.

    PubMed

    Davoli, E; Cappellini, L; Maggi, M; Fanelli, R

    1994-11-01

    An automated environmental air monitor has been developed to measure selected organic compounds in urban air. The instrument is based on a cryofocusing-thermal desorption gas chromatographic mass spectrometry technique where the mass spectrometer is a slightly modified residual gas analyzer (RGA). The RGA was chosen as a detector because the whole system must be robust for long periods, with 24-h continuous air monitoring. RCA are extremely simple and seemed the most reliable mass spectrometers for this purpose. Moreover, because they have no physically limited ion source, contamination is considerably reduced, so maintenance intervals are longer.The gas chromatograph is equipped with a computer-controlled six-way sampling valve, with a 100-mL sampling loop and thermal desorption cold trap injector. Environmental air is enriched with an isotopically labeled internal standard in the sampling line. This internal standard is added with a validated, custom-made, permeation tube device. The "on-line" internal standard provides for high quality quantitative data because all variations in instrument sensitivity in cryofocusing or in thermal desorption efficiency are taken into account. High repetition rates (down to 5 min for a full analytical cycle) are obtained with the use of an isothermal gas chromatography program, microbore capillary column, and environmental air sampling during the gas chromatography run.

  15. REAL TIME, ON-LINE CHARACTERIZATION OF DIESEL GENERATOR AIR TOXIC EMISSIONS BY RESONANCE ENHANCED MULTI-PHOTON IONIZATION TIME OF FLIGHT MASS SPECTROMETRY

    EPA Science Inventory

    The laser based resonance, enhanced multi-photon ionization time-of-flight mass spectrometry (REMPI-TOFMS) technique has been applied to the exhaust gas stream of a diesel generator to measure, in real time, concentration levels of aromatic air toxics. Volatile organic compounds ...

  16. Combining Experiments and Simulation of Gas Absorption for Teaching Mass Transfer Fundamentals: Removing CO2 from Air Using Water and NaOH

    ERIC Educational Resources Information Center

    Clark, William M.; Jackson, Yaminah Z.; Morin, Michael T.; Ferraro, Giacomo P.

    2011-01-01

    Laboratory experiments and computer models for studying the mass transfer process of removing CO2 from air using water or dilute NaOH solution as absorbent are presented. Models tie experiment to theory and give a visual representation of concentration profiles and also illustrate the two-film theory and the relative importance of various…

  17. Formic and Acetic Acid Observations over Colorado by Chemical Ionization Mass Spectrometry and Organic Acids' Role in Air Quality

    NASA Astrophysics Data System (ADS)

    Treadaway, V.; O'Sullivan, D. W.; Heikes, B.; Silwal, I.; McNeill, A.

    2015-12-01

    Formic acid (HFo) and acetic acid (HAc) have both natural and anthropogenic sources and a role in the atmospheric processing of carbon. These organic acids also have an increasing importance in setting the acidity of rain and snow as precipitation nitrate and sulfate concentrations have decreased. Primary emissions for both organic acids include biomass burning, agriculture, and motor vehicle emissions. Secondary production is also a substantial source for both acids especially from biogenic precursors, secondary organic aerosols (SOAs), and photochemical production from volatile organic compounds (VOCs) and oxygenated volatile organic compounds (OVOCs). Chemical transport models underestimate organic acid concentrations and recent research has sought to develop additional production mechanisms. Here we report HFo and HAc measurements during two campaigns over Colorado using the peroxide chemical ionization mass spectrometer (PCIMS). Iodide clusters of both HFo and HAc were recorded at mass-to-charge ratios of 173 and 187, respectively. The PCIMS was flown aboard the NCAR Gulfstream-V platform during the Deep Convective Clouds and Chemistry Experiment (DC3) and aboard the NCAR C-130 during the Front Range Air Pollution and Photochemistry Experiment (FRAPPE). The DC3 observations were made in May and June 2012 extending from the surface to 13 km over the central and eastern United States. FRAPPE observations were made in July and August 2014 from the surface to 7 km over Colorado. DC3 measurements reported here are focused over the Colorado Front Range and complement the FRAPPE observations. DC3 HFo altitude profiles are characterized by a decrease up to 6 km followed by an increase either back to boundary layer mixing ratio values or higher (a "C" shape). Organic acid measurements from both campaigns are interpreted with an emphasis on emission sources (both natural and anthropogenic) over Colorado and in situ photochemical production especially ozone precursors.

  18. A Study of Shuttlecock’s Trajectory in Badminton

    PubMed Central

    Chen, Lung-Ming; Pan, Yi-Hsiang; Chen, Yung-Jen

    2009-01-01

    The main purpose of this study was to construct and validate a motion equation for the flight of the badminton and to find the relationship between the air resistance force and a shuttlecock’s speed. This research method was based on motion laws of aerodynamics. It applied aerodynamic theories to construct motion equation of a shuttlecock’s flying trajectory under the effects of gravitational force and air resistance force. The result showed that the motion equation of a shuttlecock’s flight trajectory could be constructed by determining the terminal velocity. The predicted shuttlecock trajectory fitted the measured data fairly well. The results also revealed that the drag force was proportional to the square of a shuttlecock velocity. Furthermore, the angle and strength of a stroke could influence trajectory. Finally, this study suggested that we could use a scientific approach to measure a shuttlecock’s velocity objectively when testing the quality of shuttlecocks. And could be used to replace the traditional subjective method of the Badminton World Federation based on players’ striking shuttlecocks, as well as applying research findings to improve professional knowledge of badminton player training. Key points The motion equation of a shuttlecock’s flying trajectory could be constructed by determining the terminal velocity in aerodynamics. Air drag force is proportional to the square of a shuttlecock velocity. Furthermore, the angle and strength of a stroke could influence trajectory. PMID:24149609

  19. Optimal trajectory for the basketball free throw.

    PubMed

    Hamilton, G R; Reinschmidt, C

    1997-10-01

    Using a theoretical approach, we studied the basketball free throw as a function of angle, speed and spin at release. The ball was constrained to the sagittal plane bisecting the hoop and normal to the backboard, and was permitted to bounce and change spin on both backboard and hoop. Combinations of angle, speed and spin resulting in a successful shot were calculated analytically. Standard deviations for a shooter's angle and speed were used to predict the optimal trajectory for a specific position of release. An optimal trajectory was predicted which had an initial angle and speed of approximately 60 degrees and 7.3 m s(-1) respectively over the domain of spins (-2 to +2 m s(-1) surface speed; -16 to +16 rad s[1]). The effect of air resistance and the sagittal plane constraint on the predicted optimal trajectory were discussed and quantified. The optimal trajectory depended on both the anthropometric characteristics and accuracy of the shooter, but generally a high backspin with an angle and speed combination which sent the ball closer to the far rim of the basket than the near rim was advantageous. We provide recommendations for shooters as a function of the height of ball release.

  20. Determination of trichloroanisole and trichlorophenol in wineries' ambient air by passive sampling and thermal desorption-gas chromatography coupled to tandem mass spectrometry.

    PubMed

    Camino-Sánchez, F J; Bermúdez-Peinado, R; Zafra-Gómez, A; Ruíz-García, J; Vílchez-Quero, J L

    2015-02-01

    The present paper describes the calibration of selected passive samplers used in the quantitation of trichlorophenol and trichloroanisole in wineries' ambient air, by calculating the corresponding sampling rates. The method is based on passive sampling with sorbent tubes and involves thermal desorption-gas chromatography-triple quadrupole mass spectrometry analysis. Three commercially available sorbents were tested using sampling cartridges with a radial design instead of axial ones. The best results were found for Tenax TA™. Sampling rates (R-values) for the selected sorbents were determined. Passive sampling was also used for accurately determining the amount of compounds present in the air. Adequate correlation coefficients between the mass of the target analytes and exposure time were obtained. The proposed validated method is a useful tool for the early detection of trichloroanisole and its precursor trichlorophenol in wineries' ambient air while avoiding contamination of wine or winery facilities.

  1. Development and characterisation of a state-of-the-art GOME-2 formaldehyde air-mass factor algorithm

    NASA Astrophysics Data System (ADS)

    Hewson, W.; Barkley, M. P.; Gonzalez Abad, G.; Bösch, H.; Kurosu, T.; Spurr, R.

    2015-01-01

    Space-borne observations of formaldehyde (HCHO) are frequently used to derive surface emissions of isoprene, an important biogenic volatile organic compound. The conversion of retrieved HCHO slant column concentrations from satellite line of sight measurements to vertical columns is determined through application of an air mass factor (AMF), accounting for instrument viewing geometry, radiative transfer, and vertical profile of the absorber in the atmosphere. This step in the trace gas retrieval is subject to large errors. This work presents the AMF algorithm in use at the University of Leicester (UoL), which introduces scene specific variables into a per-observation full radiative transfer AMF calculation, including increasing spatial resolution of key environmental parameter databases, input variable area weighting, instrument specific scattering weight calculation, and inclusion of an ozone vertical profile climatology. Application of these updates to HCHO slant columns from the GOME-2 instrument is shown to typically adjust the AMF by ±10%, compared to a~reference algorithm without these advanced parameterisations. Furthermore, the new UoL algorithm also incorporates a full radiative transfer error calculation for each scene to help characterise AMF uncertainties. Global median AMF errors are typically 50-60%, and are dominated by uncertainties in the HCHO profile shape and its corresponding seasonal variation.

  2. Student understanding of the volume, mass, and pressure of air within a sealed syringe in different states of compression

    NASA Astrophysics Data System (ADS)

    de Berg, Kevin Charles

    Problem-solving strategies in the physical sciences have been characterized by a dependence on algorithmic techniques often devoid of any reasoning skills. The purpose of this study was to examine student responses to a task relating to Boyle's Law for gases, which did not demand the use of a mathematical equation for its solution. Students (17- to 18-year-olds) in lower sixth form from two colleges in the Leeds district of Yorkshire in England were asked to respond to a task relating to pressure and volume measurements of air within a sealed syringe in different states of compression. Both qualitative and quantitative tasks for the sealed syringe system were examined. It was found that 34% to 38% of students did not understand the concepts of volume and mass, respectively, of a gas under such circumstances. Performance on an inverse ratio (2:1) task was shown to depend on gender and those students who performed well on the 2:1 inverse ratio task did not necessarily perform well on a different inverse ratio task when an arithmetic averaging principle was present. Tasks which draw upon qualitative knowledge as well as quantitative knowledge have the potential to reduce dependence on algorithms, particularly equation substitution and solution. The implications for instructional design are discussed.Received: 14 April 1993; Revised: 29 June 1994;

  3. Volatile garlic odor components: gas phases and adsorbed exhaled air analysed by headspace gas chromatography-mass spectrometry.

    PubMed

    Laakso, I; Seppänen-Laakso, T; Hiltunen, R; Müller, B; Jansen, H; Knobloch, K

    1989-06-01

    Combined headspace gas chromatography-mass spectrometry (HSGC-MS) was used in the analysis of garlic volatile compounds. Twenty major components were identified in the gas phases enriched by fresh, sliced garlic cloves ( ALLIUM SATIVUM L, Allioceae, Liliidae). Suspended dry garlic powder and crushed garlic, incubated in vegetable oil, revealed a different pattern since mainly the amounts of di- and trisulfides were decreased. The considerable compositional differences found in the analyses for the gas phase of garlic cloves, kept in oil, are likely associated with the poor stability of allicin in a lipophilic environment; a marked increase in the amounts of 2-propene-1-thiol, acetic acid, and ethanol was observed in the gas phase, whereas trisulfides were present in traces only. The occurrence of 2-propene-1-thiol and diallyl disulfide, the two principal sulfur components in exhaled air, also may indicate a rapid degradation of most garlic volatile components probably caused by the enzymatically active human salivary or digestive system. PMID:17262412

  4. Effect of storm trajectories on snowfall chemistry in Rocky Mountain National Park, Colorado

    USGS Publications Warehouse

    Ingersoll, G.P.; Tonnessen, K.A.; Campbell, D.H.; Glass, B.R.; Torizzo, A.O.

    2001-01-01

    Snowfall samples from snowstorms lasting 1 to 4 days were collected near the Bear Lake snow telemetry (SnoTel) site in Rocky Mountain National Park, Colorado (ROMO), during the 1998-99 snowfall season to determine if storms moving in from different directions affect the chemistry of precipitation in the park. Storm pathways to Bear Lake during snowfall events were estimated using the HYSPLIT4 backward-trajectory model developed by the National Oceanic and Atmospheric Administration. Deposition of acidic ions of nitrate and sulfate in snowfall during the study varied substantially (two- to threefold) depending on storm trajectory because air masses traversing the park originated from different surrounding areas, including some having large sources of emissions of nitrate and sulfate. Concentrations of nitrate and sulfate in samples were lowest when storms reached ROMO from north and east of the park and were elevated when air masses traveled from the west where a number of power plants are located. Concentrations were highest in storms reaching ROMO from the south, a region with urban areas including Metropolitan Denver.

  5. OPTIMAL AIRCRAFT TRAJECTORIES FOR SPECIFIED RANGE

    NASA Technical Reports Server (NTRS)

    Lee, H.

    1994-01-01

    For an aircraft operating over a fixed range, the operating costs are basically a sum of fuel cost and time cost. While minimum fuel and minimum time trajectories are relatively easy to calculate, the determination of a minimum cost trajectory can be a complex undertaking. This computer program was developed to optimize trajectories with respect to a cost function based on a weighted sum of fuel cost and time cost. As a research tool, the program could be used to study various characteristics of optimum trajectories and their comparison to standard trajectories. It might also be used to generate a model for the development of an airborne trajectory optimization system. The program could be incorporated into an airline flight planning system, with optimum flight plans determined at takeoff time for the prevailing flight conditions. The use of trajectory optimization could significantly reduce the cost for a given aircraft mission. The algorithm incorporated in the program assumes that a trajectory consists of climb, cruise, and descent segments. The optimization of each segment is not done independently, as in classical procedures, but is performed in a manner which accounts for interaction between the segments. This is accomplished by the application of optimal control theory. The climb and descent profiles are generated by integrating a set of kinematic and dynamic equations, where the total energy of the aircraft is the independent variable. At each energy level of the climb and descent profiles, the air speed and power setting necessary for an optimal trajectory are determined. The variational Hamiltonian of the problem consists of the rate of change of cost with respect to total energy and a term dependent on the adjoint variable, which is identical to the optimum cruise cost at a specified altitude. This variable uniquely specifies the optimal cruise energy, cruise altitude, cruise Mach number, and, indirectly, the climb and descent profiles. If the optimum

  6. Quantifying ataxia: ideal trajectory analysis--a technical note

    NASA Technical Reports Server (NTRS)

    McPartland, M. D.; Krebs, D. E.; Wall, C. 3rd

    2000-01-01

    We describe a quantitative method to assess repeated stair stepping stability. In both the mediolateral (ML) and anterioposterior (AP) directions, the trajectory of the subject's center of mass (COM) was compared to an ideal sinusoid. The two identified sinusoids were unique in each direction but coupled. Two dimensionless numbers-the mediolateral instability index (IML) and AP instability index (IAP)-were calculated using the COM trajectory and ideal sinusoids for each subject with larger index values resulting from less stable performance. The COM trajectories of nine nonimpaired controls and six patients diagnosed with unilateral or bilateral vestibular labyrinth hypofunction were analyzed. The average IML and IAP values of labyrinth disorder patients were respectively 127% and 119% greater than those of controls (p<0.014 and 0.006, respectively), indicating that the ideal trajectory analysis distinguishes persons with labyrinth disorder from those without. The COM trajectories also identify movement inefficiencies attributable to vestibulopathy.

  7. Nonstationary LPV control for trajectory tracking: a double pendulum example

    NASA Astrophysics Data System (ADS)

    Farhood, Mazen

    2012-05-01

    This article focusses on the implementation of recently developed nonstationary linear-parameter varying (NSLPV) control algorithms for the regulation of nonlinear systems about pre-specified trajectories. The trajectories of interest eventually settle into periodic orbits, and hence are duly called eventually periodic trajectories. Parameterising the nonlinear system equations about such trajectories results in eventually periodic NSLPV models, and then NSLPV controllers are designed for these models to ensure accurate trajectory tracking despite various disturbances and uncertainties. These control algorithms will be applied to control a double pendulum where a vessel containing fluid is rigidly attached to the end of the second link of the pendulum. The mass of the fluid varies in time and, together with its rate of variation, is available for measurement during plant operation.

  8. Methods, fluxes and sources of gas phase alkyl nitrates in the coastal air.

    PubMed

    Dirtu, Alin C; Buczyńska, Anna J; Godoi, Ana F L; Favoreto, Rodrigo; Bencs, László; Potgieter-Vermaak, Sanja S; Godoi, Ricardo H M; Van Grieken, René; Van Vaeck, Luc

    2014-10-01

    The daily and seasonal atmospheric concentrations, deposition fluxes and emission sources of a few C3-C9 gaseous alkyl nitrates (ANs) at the Belgian coast (De Haan) on the Southern North Sea were determined. An adapted sampler design for low- and high-volume air-sampling, optimized sample extraction and clean-up, as well as identification and quantification of ANs in air samples by means of gas chromatography mass spectrometry, are reported. The total concentrations of ANs ranged from 0.03 to 85 pptv and consisted primarily of the nitro-butane and nitro-pentane isomers. Air mass backward trajectories were calculated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to determine the influence of main air masses on AN levels in the air. The shorter chain ANs have been the most abundant in the Atlantic/Channel/UK air masses, while longer chain ANs prevailed in continental air. The overall mean N fluxes of the ANs were slightly higher for summer than those for winter-spring, although their contributions to the total nitrogen flux were low. High correlations between AN and HNO₂ levels were observed during winter/spring. During summer, the shorter chain ANs correlated well with precipitation. Source apportionment by means of principal component analysis indicated that most of the gas phase ANs could be attributed to traffic/combustion, secondary photochemical formation and biomass burning, although marine sources may also have been present and a contributing factor. PMID:24952420

  9. Methods, fluxes and sources of gas phase alkyl nitrates in the coastal air.

    PubMed

    Dirtu, Alin C; Buczyńska, Anna J; Godoi, Ana F L; Favoreto, Rodrigo; Bencs, László; Potgieter-Vermaak, Sanja S; Godoi, Ricardo H M; Van Grieken, René; Van Vaeck, Luc

    2014-10-01

    The daily and seasonal atmospheric concentrations, deposition fluxes and emission sources of a few C3-C9 gaseous alkyl nitrates (ANs) at the Belgian coast (De Haan) on the Southern North Sea were determined. An adapted sampler design for low- and high-volume air-sampling, optimized sample extraction and clean-up, as well as identification and quantification of ANs in air samples by means of gas chromatography mass spectrometry, are reported. The total concentrations of ANs ranged from 0.03 to 85 pptv and consisted primarily of the nitro-butane and nitro-pentane isomers. Air mass backward trajectories were calculated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to determine the influence of main air masses on AN levels in the air. The shorter chain ANs have been the most abundant in the Atlantic/Channel/UK air masses, while longer chain ANs prevailed in continental air. The overall mean N fluxes of the ANs were slightly higher for summer than those for winter-spring, although their contributions to the total nitrogen flux were low. High correlations between AN and HNO₂ levels were observed during winter/spring. During summer, the shorter chain ANs correlated well with precipitation. Source apportionment by means of principal component analysis indicated that most of the gas phase ANs could be attributed to traffic/combustion, secondary photochemical formation and biomass burning, although marine sources may also have been present and a contributing factor.

  10. Trajectory Optimization: OTIS 4

    NASA Technical Reports Server (NTRS)

    Riehl, John P.; Sjauw, Waldy K.; Falck, Robert D.; Paris, Stephen W.

    2010-01-01

    The latest release of the Optimal Trajectories by Implicit Simulation (OTIS4) allows users to simulate and optimize aerospace vehicle trajectories. With OTIS4, one can seamlessly generate optimal trajectories and parametric vehicle designs simultaneously. New features also allow OTIS4 to solve non-aerospace continuous time optimal control problems. The inputs and outputs of OTIS4 have been updated extensively from previous versions. Inputs now make use of objectoriented constructs, including one called a metastring. Metastrings use a greatly improved calculator and common nomenclature to reduce the user s workload. They allow for more flexibility in specifying vehicle physical models, boundary conditions, and path constraints. The OTIS4 calculator supports common mathematical functions, Boolean operations, and conditional statements. This allows users to define their own variables for use as outputs, constraints, or objective functions. The user-defined outputs can directly interface with other programs, such as spreadsheets, plotting packages, and visualization programs. Internally, OTIS4 has more explicit and implicit integration procedures, including high-order collocation methods, the pseudo-spectral method, and several variations of multiple shooting. Users may switch easily between the various methods. Several unique numerical techniques such as automated variable scaling and implicit integration grid refinement, support the integration methods. OTIS4 is also significantly more user friendly than previous versions. The installation process is nearly identical on various platforms, including Microsoft Windows, Apple OS X, and Linux operating systems. Cross-platform scripts also help make the execution of OTIS and post-processing of data easier. OTIS4 is supplied free by NASA and is subject to ITAR (International Traffic in Arms Regulations) restrictions. Users must have a Fortran compiler, and a Python interpreter is highly recommended.

  11. Evaluation of chemical transport model predictions of primary organic aerosol for air masses classified by particle-component-based factor analysis

    NASA Astrophysics Data System (ADS)

    Stroud, C. A.; Moran, M. D.; Makar, P. A.; Gong, S.; Gong, W.; Zhang, J.; Slowik, J. G.; Abbatt, J. P. D.; Lu, G.; Brook, J. R.; Mihele, C.; Li, Q.; Sills, D.; Strawbridge, K. B.; McGuire, M. L.; Evans, G. J.

    2012-02-01

    Observations from the 2007 Border Air Quality and Meteorology Study (BAQS-Met 2007) in southern Ontario (ON), Canada, were used to evaluate Environment Canada's regional chemical transport model predictions of primary organic aerosol (POA). Environment Canada's operational numerical weather prediction model and the 2006 Canadian and 2005 US national emissions inventories were used as input to the chemical transport model (named AURAMS). Particle-component-based factor analysis was applied to aerosol mass spectrometer measurements made at one urban site (Windsor, ON) and two rural sites (Harrow and Bear Creek, ON) to derive hydrocarbon-like organic aerosol (HOA) factors. Co-located carbon monoxide (CO), PM2.5 black carbon (BC), and PM1 SO4 measurements were also used for evaluation and interpretation, permitting a detailed diagnostic model evaluation. At the urban site, good agreement was observed for the comparison of daytime campaign PM1 POA and HOA mean values: 1.1 μg m-3 vs. 1.2 μg m-3, respectively. However, a POA overprediction was evident on calm nights due to an overly-stable model surface layer. Biases in model POA predictions trended from positive to negative with increasing HOA values. This trend has several possible explanations, including (1) underweighting of urban locations in particulate matter (PM) spatial surrogate fields, (2) overly-coarse model grid spacing for resolving urban-scale sources, and (3) lack of a model particle POA evaporation process during dilution of vehicular POA tail-pipe emissions to urban scales. Furthermore, a trend in POA bias was observed at the urban site as a function of the BC/HOA ratio, suggesting a possible association of POA underprediction for diesel combustion sources. For several time periods, POA overprediction was also observed for sulphate-rich plumes, suggesting that our model POA fractions for the PM2.5 chemical speciation profiles may be too high for these point sources. At the rural Harrow site

  12. Irreversibility with quantum trajectories.

    PubMed

    Wisniacki, D A; Borondo, F; Benito, R M

    2005-10-01

    Irreversibility is an important issue for many quantum processes. Loschmidt echoes, originally introduced as a way to gauge sensitivity to perturbations in quantum mechanics, have turned out to be a useful tool for its investigation. Following the philosophy supporting this idea, and using quantum trajectories as defined in the causal interpretation of quantum mechanics due to Bohm, we introduce in this paper a more informative alternative measure for irreversibility. The method is applied to the Bunimovich stadium billiard, a paradigmatic example of chaotic system, that constitutes an excellent model for mesoscopic devices.

  13. Dynamical collapse of trajectories

    NASA Astrophysics Data System (ADS)

    Biemond, J. J. Benjamin; de Moura, Alessandro P. S.; Grebogi, Celso; van de Wouw, Nathan; Nijmeijer, Henk

    2012-04-01

    Friction induces unexpected dynamical behaviour. In the paradigmatic pendulum and double-well systems with friction, modelled with differential inclusions, distinct trajectories can collapse onto a single point. Transversal homoclinic orbits display collapse and generate chaotic saddles with forward dynamics that is qualitatively different from the backward dynamics. The space of initial conditions converging to the chaotic saddle is fractal, but the set of points diverging from it is not: friction destroys the complexity of the forward dynamics by generating a unique horseshoe-like topology.

  14. Trajectory optimization for an asymmetric launch vehicle. M.S. Thesis - MIT

    NASA Technical Reports Server (NTRS)

    Sullivan, Jeanne Marie

    1990-01-01

    A numerical optimization technique is used to fully automate the trajectory design process for an symmetric configuration of the proposed Advanced Launch System (ALS). The objective of the ALS trajectory design process is the maximization of the vehicle mass when it reaches the desired orbit. The trajectories used were based on a simple shape that could be described by a small set of parameters. The use of a simple trajectory model can significantly reduce the computation time required for trajectory optimization. A predictive simulation was developed to determine the on-orbit mass given an initial vehicle state, wind information, and a set of trajectory parameters. This simulation utilizes an idealized control system to speed computation by increasing the integration time step. The conjugate gradient method is used for the numerical optimization of on-orbit mass. The method requires only the evaluation of the on-orbit mass function using the predictive simulation, and the gradient of the on-orbit mass function with respect to the trajectory parameters. The gradient is approximated with finite differencing. Prelaunch trajectory designs were carried out using the optimization procedure. The predictive simulation is used in flight to redesign the trajectory to account for trajectory deviations produced by off-nominal conditions, e.g., stronger than expected head winds.

  15. Size-Segregated Aerosol Composition and Mass Loading of Atmospheric Particles as Part of the Pacific Northwest 2001(PNW2001) Air Quality Study In Puget Sound

    NASA Astrophysics Data System (ADS)

    Disselkamp, R. S.; Barrie, L. A.; Shutthanadan, S.; Cliff, S.; Cahill, T.

    2001-12-01

    In mid-August, 2001, an aircraft-based air-quality study was performed in the Puget Sound, WA, area entitled PNW2001 (http://www.pnl.gov/pnw2001). The objectives of this field campaign were the following: 1. reveal information about the 3-dimensional distribution of ozone, its gaseous precursors and fine particulate matter during weather conditions favoring air pollution; 2. derive information about the accuracy of urban and biogenic emissions inventories that are used to drive the air quality forecast models; and 3. examine the accuracy of modeled ozone concentration with that observed. In support of these efforts, we collected time-averaged ( { ~}10 minute averages), size-segregated, aerosol composition and mass-loading information using ex post facto analysis techniques of synchrotron x-ray fluorescence (s-XRF), proton induced x-ray emissions(PIXE), proton elastic scattering (PESA), and scanning transmission ion microscopy (STIM). This is the first time these analysis techniques have been used together on samples collected from aircraft using an optimized 3-stage rotating drum impactor. In our presentation, we will discuss the aerosol components in three aerosol size fractions as identified by statistical analysis of multielemental data (including total mass, H, Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Pb) and relate variations in these components to physical aerosol properties, other gaseous trace constituents and to air mass origin.

  16. A Method of Trajectory Design for Manned Asteroids Exploration

    NASA Astrophysics Data System (ADS)

    Gan, Q. B.; Zhang, Y.; Zhu, Z. F.; Han, W. H.; Dong, X.

    2014-11-01

    A trajectory optimization method of the nuclear propulsion manned asteroids exploration is presented. In the case of launching between 2035 and 2065, based on the Lambert transfer orbit, the phases of departure from and return to the Earth are searched at first. Then the optimal flight trajectory in the feasible regions is selected by pruning the flight sequences. Setting the nuclear propulsion flight plan as propel-coast-propel, and taking the minimal mass of aircraft departure as the index, the nuclear propulsion flight trajectory is separately optimized using a hybrid method. With the initial value of the optimized local parameters of each three phases, the global parameters are jointedly optimized. At last, the minimal departure mass trajectory design result is given.

  17. Optimal trajectories for hypersonic launch vehicles

    NASA Astrophysics Data System (ADS)

    Ardema, Mark D.; Bowles, Jeffrey V.; Whittaker, Thomas

    In this paper, we derive a near-optimal guidance law for the ascent trajectory from Earth surface to Earth orbit of a hypersonic, dual-mode propulsion, lifting vehicle. Of interest are both the optimal flight path and the optimal operation of the propulsion system. The guidance law is developed from the energy-state approximation of the equations of motion. The performance objective is a weighted sum of fuel mass and volume, with the weighting factor selected to give minimum gross take-off weight for a specific payload mass and volume.

  18. Optimal trajectories for hypersonic launch vehicles

    NASA Astrophysics Data System (ADS)

    Ardema, Mark D.; Bowles, Jeffrey V.; Whittaker, Thomas

    1994-10-01

    In this paper, we derive a near-optimal guidance law for the ascent trajectory from earth surface to earth orbit of a hypersonic, dual-mode propulsion, lifting vehicle. Of interest are both the optical flight path and the optimal operation of the propulsion system. The guidance law is developed from the energy-state approximation of the equations of motion. Because liquid hydrogen fueled hypersonic aircraft are volume sensitive, as well as weight sensitive, the cost functional is a weighted sum of fuel mass and volume; the weighting factor is chosen to minimize gross take-off weight for a given payload mass and volume in orbit.

  19. Development of a Mars Airplane Entry, Descent, and Flight Trajectory

    NASA Technical Reports Server (NTRS)

    Murray, James E.; Tartabini, Paul V.

    2001-01-01

    An entry, descent, and flight (EDF) trajectory profile for a Mars airplane mission is defined as consisting of the following elements: ballistic entry of an aeroshell; supersonic deployment of a decelerator parachute; subsonic release of a heat shield; release, unfolding, and orientation of an airplane to flight attitude; and execution of a pull up maneuver to achieve trimmed, horizontal flight. Using the Program to Optimize Simulated Trajectories (POST) a trajectory optimization problem was formulated. Model data representative of a specific Mars airplane configuration, current models of the Mars surface topography and atmosphere, and current estimates of the interplanetary trajectory, were incorporated into the analysis. The goal is to develop an EDF trajectory to maximize the surface-relative altitude of the airplane at the end of a pull up maneuver, while subject to the mission design constraints. The trajectory performance was evaluated for three potential mission sites and was found to be site-sensitive. The trajectory performance, examined for sensitivity to a number of design and constraint variables, was found to be most sensitive to airplane mass, aerodynamic performance characteristics, and the pull up Mach constraint. Based on the results of this sensitivity study, an airplane-drag optimized trajectory was developed that showed a significant performance improvement.

  20. Characterization of ion processes in a GC/DMS air quality monitor by integration of the instrument to a mass spectrometer.

    PubMed

    Limero, T F; Nazarov, E G; Menlyadiev, M; Eiceman, G A

    2015-02-01

    The air quality monitor (AQM), which included a portable gas chromatograph (GC) and a detector was interfaced to a mass spectrometer (MS) by introducing flow from the GC detector to the atmospheric pressure ion source of the MS. This small GC system, with a gas recirculation loop for carrier and detector make-up gases, comprised an inlet to preconcentrate volatile organic compounds (VOCs) in air, a thermal desorber before the GC column, a differential mobility spectrometer (DMS), and another DMS as an atmospheric pressure ionization source for the MS. Return flow to the internally recirculated air system of the AQM's DMS was replenished using purified air. Although ions and unreacted neutral vapors flowed from the detector through Viton® tubing into the source of the MS, ions were not detected in the MS without the auxillary ion source, (63)Ni as in the mobility detector. The GC-DMS-MS instrument provided a 3-D measurement platform (GC, DMS, and MS analysis) to explore the gas composition inside the GC-DMS recirculation loop and provide DMS-MS measurement of the components of a complex VOC mixture with performance significantly enhanced by mass-analysis, either with mass spectral scans or with an extracted ion chromatogram. This combination of a mobility spectrometer and a mass spectrometer was possible as vapors and ions are carried together through the DMS analyzer, thereby preserving the chromatographic separation efficiency. The critical benefit of this instrument concept is that all flows in and through the thoroughly integrated GC-DMS analyzer are kept intact allowing a full measure of the ion and vapor composition in the complete system. Performance has been evaluated using a synthetic air sample and a sample of airborne vapors in a laboratory. Capabilities and performance values are described using results from AQM-MS analysis of purified air, ambient air from a research laboratory in a chemistry building, and a sample of synthetic air of known composition

  1. Trajectories in parallel optics.

    PubMed

    Klapp, Iftach; Sochen, Nir; Mendlovic, David

    2011-10-01

    In our previous work we showed the ability to improve the optical system's matrix condition by optical design, thereby improving its robustness to noise. It was shown that by using singular value decomposition, a target point-spread function (PSF) matrix can be defined for an auxiliary optical system, which works parallel to the original system to achieve such an improvement. In this paper, after briefly introducing the all optics implementation of the auxiliary system, we show a method to decompose the target PSF matrix. This is done through a series of shifted responses of auxiliary optics (named trajectories), where a complicated hardware filter is replaced by postprocessing. This process manipulates the pixel confined PSF response of simple auxiliary optics, which in turn creates an auxiliary system with the required PSF matrix. This method is simulated on two space variant systems and reduces their system condition number from 18,598 to 197 and from 87,640 to 5.75, respectively. We perform a study of the latter result and show significant improvement in image restoration performance, in comparison to a system without auxiliary optics and to other previously suggested hybrid solutions. Image restoration results show that in a range of low signal-to-noise ratio values, the trajectories method gives a significant advantage over alternative approaches. A third space invariant study case is explored only briefly, and we present a significant improvement in the matrix condition number from 1.9160e+013 to 34,526.

  2. Development and characterisation of a state-of-the-art GOME-2 formaldehyde air-mass factor algorithm

    NASA Astrophysics Data System (ADS)

    Hewson, W.; Barkley, M. P.; Gonzalez Abad, G.; Bösch, H.; Kurosu, T.; Spurr, R.; Tilstra, L. G.

    2015-10-01

    Space-borne observations of formaldehyde (HCHO) are frequently used to derive surface emissions of isoprene, an important biogenic volatile organic compound. The conversion of retrieved HCHO slant column concentrations from satellite line-of-sight measurements to vertical columns is determined through application of an air mass factor (AMF), accounting for instrument viewing geometry, radiative transfer, and vertical profile of the absorber in the atmosphere. This step in the trace gas retrieval is subject to large errors. This work presents the AMF algorithm in use at the University of Leicester (UoL), which introduces scene-specific variables into a per-observation full radiative transfer AMF calculation, including increasing spatial resolution of key environmental parameter databases, input variable area weighting, instrument-specific scattering weight calculation, and inclusion of an ozone vertical profile climatology. Application of these updates to HCHO slant columns from the GOME-2 instrument is shown to typically adjust the AMF by ±20 %, compared to a reference algorithm without these advanced parameterisations. On average the GOME-2 AMFs increase by 4 %, with over 70 % of locations having an AMF of 0-20 % larger than originally, largely resulting from the use of the latest GOME-2 reflectance product. Furthermore, the new UoL algorithm also incorporates a full radiative transfer error calculation for each scene to help characterise AMF uncertainties. Global median AMF errors are typically 50-60 %, and are driven by uncertainties in the HCHO profile shape and its vertical distribution relative to clouds and aerosols. If uncertainty on the a priori HCHO profile is relatively small (< 10 %) then the median AMF total error decreases to about 30-40 %.

  3. Air Mass Factor Formulation for Spectroscopic Measurements from Satellites: Application to Formaldehyde Retrievals from the Global Ozone Monitoring Experiment

    NASA Technical Reports Server (NTRS)

    Palmer, Paul I.; Jacob, Daniel J.; Chance, Kelly; Martin, Randall V.; Spurr, Robert J. D.; Kurosu, Thomas P.; Bey, Isabelle; Yantosca, Robert; Fiore, Arlene; Li, Qinbin

    2004-01-01

    We present a new formulation for the air mass factor (AMF) to convert slant column measurements of optically thin atmospheric species from space into total vertical columns. Because of atmospheric scattering, the AMF depends on the vertical distribution of the species. We formulate the AMF as the integral of the relative vertical distribution (shape factor) of the species over the depth of the atmosphere, weighted by altitude-dependent coefficients (scattering weights) computed independently from a radiative transfer model. The scattering weights are readily tabulated, and one can then obtain the AMF for any observation scene by using shape factors from a three dimensional (3-D) atmospheric chemistry model for the period of observation. This approach subsequently allows objective evaluation of the 3-D model with the observed vertical columns, since the shape factor and the vertical column in the model represent two independent pieces of information. We demonstrate the AMF method by using slant column measurements of formaldehyde at 346 nm from the Global Ozone Monitoring Experiment satellite instrument over North America during July 1996. Shape factors are cumputed with the Global Earth Observing System CHEMistry (GEOS-CHEM) global 3-D model and are checked for consistency with the few available aircraft measurements. Scattering weights increase by an order of magnitude from the surface to the upper troposphere. The AMFs are typically 20-40% less over continents than over the oceans and are approximately half the values calculated in the absence of scattering. Model-induced errors in the AMF are estimated to be approximately 10%. The GEOS-CHEM model captures 50% and 60% of the variances in the observed slant and vertical columns, respectively. Comparison of the simulated and observed vertical columns allows assessment of model bias.

  4. Titan Explorer Entry, Descent and Landing Trajectory Design

    NASA Technical Reports Server (NTRS)

    Fisher, Jody L.; Lindberg, Robert E.; Lockwood, Mary Kae

    2006-01-01

    The Titan Explorer mission concept includes an orbiter, entry probe and inflatable airship designed to take remote and in-situ measurements of Titan's atmosphere. A modified entry, descent and landing trajectory at Titan that incorporates mid-air airship inflation (under a parachute) and separation is developed and examined for Titan Explorer. The feasibility of mid-air inflation and deployment of an airship under a parachute is determined by implementing and validating an airship buoyancy and inflation model in the trajectory simulation program, Program to Optimize Simulated Trajectories II (POST2). A nominal POST2 trajectory simulation case study is generated which examines different descent scenarios by varying airship inflation duration, orientation, and separation. The buoyancy model incorporation into POST2 is new to the software and may be used in future trajectory simulations. Each case from the nominal POST2 trajectory case study simulates a successful separation between the parachute and airship systems with sufficient velocity change as to alter their paths to avoid collision throughout their descent. The airship and heatshield also separate acceptably with a minimum distance of separation from the parachute system of 1.5 km. This analysis shows the feasibility of airship inflation on a parachute for different orientations, airship separation at various inflation times, and preparation for level-flight at Titan.

  5. Mobile selected ion flow tube mass spectrometry (SIFT-MS) devices and their use for pollution exposure monitoring in breath and ambient air-pilot study.

    PubMed

    Storer, Malina; Salmond, Jennifer; Dirks, Kim N; Kingham, Simon; Epton, Michael

    2014-09-01

    Studies of health effects of air pollution exposure are limited by inability to accurately determine dose and exposure of air pollution in field trials. We explored the feasibility of using a mobile selected ion flow tube mass spectrometry (SIFT-MS) device, housed in a van, to determine ambient air and breath levels of benzene, xylene and toluene following exercise in areas of high motor vehicle traffic. The breath toluene, xylene and benzene concentration of healthy subjects were measured before and after exercising close to a busy road. The concentration of the volatile organic compounds (VOCs), in ambient air were also analysed in real time. Exercise close to traffic pollution is associated with a two-fold increase in breath VOCs (benzene, xylene and toluene) with levels returning to baseline within 20 min. This effect is not seen when exercising away from traffic pollution sources. Situating the testing device 50 m from the road reduced any confounding due to VOCs in the inspired air prior to the breath testing manoeuvre itself. Real-time field testing for air pollution exposure is possible using a mobile SIFT-MS device. This device is suitable for exploring exposure and dose relationships in a number of large scale field test scenarios.

  6. Characteristics of particle number and mass emissions during heavy-duty diesel truck parked active DPF regeneration in an ambient air dilution tunnel

    NASA Astrophysics Data System (ADS)

    Yoon, Seungju; Quiros, David C.; Dwyer, Harry A.; Collins, John F.; Burnitzki, Mark; Chernich, Donald; Herner, Jorn D.

    2015-12-01

    Diesel particle number and mass emissions were measured during parked active regeneration of diesel particulate filters (DPF) in two heavy-duty diesel trucks: one equipped with a DPF and one equipped with a DPF + SCR (selective catalytic reduction), and compliant with the 2007 and 2010 emission standards, respectively. The emission measurements were conducted using an ambient air dilution tunnel. During parked active regeneration, particulate matter (PM) mass emissions measured from a 2007 technology truck were significantly higher than the emissions from a 2010 technology truck. Particle number emissions from both trucks were dominated by nucleation mode particles having a diameter less than 50 nm; nucleation mode particles were orders of magnitude higher than accumulation mode particles having a diameter greater than 50 nm. Accumulation mode particles contributed 77.8 %-95.8 % of the 2007 truck PM mass, but only 7.3 %-28.2 % of the 2010 truck PM mass.

  7. Probabilistic Modeling of Aircraft Trajectories for Dynamic Separation Volumes

    NASA Technical Reports Server (NTRS)

    Lewis, Timothy A.

    2016-01-01

    With a proliferation of new and unconventional vehicles and operations expected in the future, the ab initio airspace design will require new approaches to trajectory prediction for separation assurance and other air traffic management functions. This paper presents an approach to probabilistic modeling of the trajectory of an aircraft when its intent is unknown. The approach uses a set of feature functions to constrain a maximum entropy probability distribution based on a set of observed aircraft trajectories. This model can be used to sample new aircraft trajectories to form an ensemble reflecting the variability in an aircraft's intent. The model learning process ensures that the variability in this ensemble reflects the behavior observed in the original data set. Computational examples are presented.

  8. Easy dual-mode ambient mass spectrometry with Venturi self-pumping, canned air, disposable parts and voltage-free sonic-spray ionization.

    PubMed

    Schwab, Nicolas V; Porcari, Andreia M; Coelho, Mirela B; Schmidt, Eduardo M; Jara, Jose L; Visentainer, Jesui V; Eberlin, Marcos N

    2012-06-01

    An exceptionally easy to assemble source for ambient mass spectrometry is described. Based on Venturi easy ambient sonic-spray ionization (V-EASI), the source was further simplified by the use of a can of compressed air which simultaneously provides solution or solvent Venturi self-pumping and continuous, stable and abundant low-noise ion signal via voltage-free sonic-spraying. Further simplification was also attained by the use of inexpensive and readily commercially available parts: a surgical 2-way catheter, an aerosol can of compressed air, a 30 cm long fused-silica capillary and a hypodermic needle. This "Spartan" V-EASI source seems to offer one of the easiest and cheapest ways to make ions for ambient desorption/ionization mass spectrometry analysis of both liquid and solid samples. PMID:22349120

  9. Jettison Engineering Trajectory Tool

    NASA Technical Reports Server (NTRS)

    Zaczek, Mariusz; Walter, Patrick; Pascucci, Joseph; Armstrong, Phyllis; Hallbick, Patricia; Morgan, Randal; Cooney, James

    2013-01-01

    The Jettison Engineering Trajectory Tool (JETT) performs the jettison analysis function for any orbiting asset. It provides a method to compute the relative trajectories between an orbiting asset and any jettisoned item (intentional or unintentional) or sublimating particles generated by fluid dumps to assess whether an object is safe to jettison, or if there is a risk with an item that was inadvertently lost overboard. The main concern is the interaction and possible recontact of the jettisoned object with an asset. This supports the analysis that jettisoned items will safely clear the vehicle, ensuring no collisions. The software will reduce the jettison analysis task from one that could take days to complete to one that can be completed in hours, with an analysis that is more comprehensive than the previous method. It provides the ability to define the jettison operation relative to International Space Station (ISS) structure, and provides 2D and 3D plotting capability to allow an analyst to perform a subjective clearance assessment with ISS structures. The developers followed the SMP to create the code and all supporting documentation. The code makes extensive use of the object-oriented format of Java and, in addition, the Model-View-Controller architecture was used in the organization of the code, allowing each piece to be independent of updates to the other pieces. The model category is for maintaining data entered by the user and generated by the analysis. The view category provides capabilities for data entry and displaying all or a portion of the analysis data in tabular, 2D, and 3D representation. The controller category allows for handling events that affect the model or view(s). The JETT utilizes orbital mechanics with complex algorithms. Since JETT is written in JAVA, it is essentially platform-independent.

  10. Who should take responsibility for decisions on internationally recommended datasets? The case of the mass concentration of mercury in air at saturation

    NASA Astrophysics Data System (ADS)

    Brown, Richard J. C.; Brewer, Paul J.; Ent, Hugo; Fisicaro, Paola; Horvat, Milena; Kim, Ki-Hyun; Quétel, Christophe R.

    2015-10-01

    This paper considers how decisions on internationally recommended datasets are made and implemented and, further, how the ownership of these decisions comes about. Examples are given of conventionally agreed data and values where the responsibility is clear and comes about through official designation or by common usage and practice over long time periods. The example of the dataset describing the mass concentration of mercury in air at saturation is discussed in detail. This is a case where there are now several competing datasets that are in disagreement with each other, some with historical authority and some more recent but, arguably, with more robust metrological traceability to the SI. Further, it is elaborated that there is no body charged with the responsibility to make a decision on an international recommendation for such a dataset. This has led to the situation where several competing datasets are in use simultaneously. Close parallels are drawn with the current debate over changes to the ozone absorption cross section, which has equal importance to the measurement of ozone amount fraction in air and to subsequent compliance with air quality legislation. It is noted that in the case of the ozone cross section there is already a committee appointed to deliberate over any change. We make the proposal that a similar committee, under the auspices of IUPAC or the CIPM’s CCQM (if it adopted a reference data function) could be formed to perform a similar role for the mass concentration of mercury in air at saturation.

  11. Ares I-X Best Estimated Trajectory and Comparison with Pre-Flight Predictions

    NASA Technical Reports Server (NTRS)

    Karlgaard, Christopher D.; Beck, Roger E.; Derry, Stephen D.; Brandon, Jay M.; Starr, Brett R.; Tartabini, Paul V.; Olds, Aaron D.

    2011-01-01

    The Ares I-X trajectory reconstruction produced best estimated trajectories of the flight test vehicle ascent through stage separation, and of the first and upper stage entries after separation. The trajectory reconstruction process combines on-board, ground-based, and atmospheric measurements to produce the trajectory estimates. The Ares I-X vehicle had a number of on-board and ground based sensors that were available, including inertial measurement units, radar, air- data, and weather balloons. However, due to problems with calibrations and/or data, not all of the sensor data were used. The trajectory estimate was generated using an Iterative Extended Kalman Filter algorithm, which is an industry standard processing algorithm for filtering and estimation applications. This paper describes the methodology and results of the trajectory reconstruction process, including flight data preprocessing and input uncertainties, trajectory estimation algorithms, output transformations, and comparisons with preflight predictions.

  12. Energy methods for hypersonic trajectory optimization

    NASA Astrophysics Data System (ADS)

    Chou, Han-Chang

    A family of near-optimal guidance laws for the ascent and descent trajectories between earth surface and earth orbit of fully reusable single-stage-to-orbit launch vehicles is derived. Of interest are both the optimal operation of the propulsion system and the optimal flight path. The method is based on selecting propulsion system modes and flight-path parameters that maximize a certain performance function. This function is derived from consideration of the energy-state model of the aircraft equations of motion. For ascent trajectories of vehicles employing hydrogen fuel, because the density of liquid hydrogen is relatively low, the sensitivity to perturbations in volume needs to be taken into consideration as well as weight sensitivity. The cost functional is then a weighted sum of fuel mass and volume; the weighting factor is chosen to minimize vehicle empty weight for a given payload mass and volume in orbit. Both airbreathing/rocket and all rocket propulsion systems are considered. For airbreathing/rocket vehicles, the optimal propulsion switching Mach numbers are determined and the use of liquid oxygen augmentation is investigated. For the vehicles with all rocket power, the desirability of tripropellant systems is investigated. In addition, time and heat load is minimized as well. For descent trajectories, the trade-off between minimizing heat load into the vehicle and maximizing cross range distance is investigated, as well as minimum time and minimum temperature paths. The results show that the optimization methodology can be used to derive a wide variety of near-optimal launch vehicle trajectories.

  13. Variation in airborne 137Cs peak levels with altitude from high-altitude locations across Europe after the arrival of Fukushima-labeled air masses

    NASA Astrophysics Data System (ADS)

    Masson, Olivier; Bieringer, Jacqueline; Dalheimer, Axel; Estier, Sybille; Evrard, Olivier; Penev, Ilia; Ringer, Wolfgang; Schlosser, Clemens; Steinkopff, Thomas; Tositti, Laura; de Vismes-Ott, Anne

    2015-04-01

    During the Fukushima Daiichi nuclear power plant (FDNPP) accident, a dozen of high-altitude aerosol sampling stations, located between 850 and 3,454 m above sea level (a.s.l.), provided airborne activity levels across Europe (Fig. 1). This represents at most 5% of the total number of aerosol sampling locations that delivered airborne activity levels (at least one result) in Europe, in connection with this nuclear accident. High altitude stations are typically equipped with a high volume sampler that collects aerosols on filters. The Fukushima-labeled air mass arrival and the peak of airborne cesium-137 (137Cs) activity levels were registered in Europe at different dates depending on the location, with differences up to a factor of six on a regional scale. Besides this statement related to lowland areas, we have compared the maximum airborne levels registered at high-altitude European locations (850 m < altitudes < 3450 m) with what was observed at the closest lowland location. The vertical distribution of 137Cs peak level was not uniform even after a long travel time/distance from Japan. This being true at least in the atmospheric boundary layer and in the lower free troposphere. Moreover the relation '137Csmax vs. altitude' shows a decreasing trend (Fig. 2). Results and discussion : Comparison of 137Cs and 7Be levels shows simultaneous increases at least when the 137Cs airborne level rose for the first time (Fig. 3). Zugspitze and Jungfraujoch stations attest of a time shift between 7Be and 137Cs peak that can be due to the particular dynamic of air movements at such high altitudes. After the 137Cs peak value, the plume concentration decreased whatever the 7Be level. Due to the cosmogenic origin of 7Be, its increase in the ground-level air is usually associated with downwind air movements, i.e. stratospheric air intrusions or at least air from high-tropospheric levels, into lower atmospheric layers. This means that Fukushima-labeled air masses registered at ground

  14. Retrieval of Vertical Columns of Sulfur Dioxide From SCIAMACHY and OMI: Air Mass Factor Algorithm Development and Validation

    NASA Astrophysics Data System (ADS)

    Lee, C.; Martin, R. V.; Donkelaar, A. V.; O'Byrne, G.; Krotkov, N.; Richter, A.; Huey, G.; Holloway, J. S.

    2009-05-01

    Sulfur dioxide (SO2) is released into the atmosphere as a result of both anthropogenic activities and natural phenomena. SO2 oxidizes rapidly in the atmosphere, leading to aerosol formation and acid deposition. Outstanding questions exist about SO2 emissions and its atmospheric chemistry. Global mapping of atmospheric SO2 concentrations can provide critical information on its emissions and transport and generally improve scientific understanding of its atmospheric chemistry. Here, we present an improved retrieval of sulfur dioxide (SO2) vertical columns from satellite instruments (SCIAMACHY and OMI) that measure solar backscattered UV radiance. Particular attention is devoted to development of a local air mass factor (AMF) algorithm to convert slant columns to vertical columns. For each SCIAMACHY and OMI observation, we calculate an AMF from the relative vertical SO2 distribution (shape factor) determined locally with a 3-D global model of atmospheric chemistry (GEOS-Chem), weighted by altitude-dependent scattering weights computed with a radiative transfer model (LIDORT). Seasonal mean instrument sensitivity to SO2 (AMF) is generally twice as high over ocean than land. Mineral dust can reduce seasonal mean instrument sensitivity by 50%. Mean relative vertical profiles of SO2 simulated with GEOS-Chem and used in the AMF calculation are highly consistent with airborne in situ measurements (INTEX-A and INTEX-B); differences would affect the retrieved SO2 columns by 10%. The retrieved vertical columns are validated (r = 0.9) with coincident airborne in-situ measurements (INTEX-A, INTEX-B, and a campaign over East China). A global uniform AMF would reduce the correlation with aircraft measurements by 0.1 - 0.2. The overall error assessment leads to 45 - 80% errors for yearly averages over the polluted regions. Seasonal mean SO2 columns retrieved from SCIAMACHY and OMI for 2006 are significantly spatially correlated with those from GEOS-Chem, in particular over the

  15. Intercomparison of OMI NO2 and HCHO air mass factor calculations: recommendations and best practices for retrievals

    NASA Astrophysics Data System (ADS)

    Lorente Delgado, Alba; Klaas Boersma, Folkert; Hilboll, Andreas; Richter, Andreas; Yu, Huan; van Roozendael, Michel; Dörner, Steffen; Wagner, Thomas; Barkley, Michael; Lamsal, Lok; Lin, Jintai; Liu, Mengyao

    2016-04-01

    We present a detailed comparison of the air mass factor (AMF) calculation process used by various research groups for OMI satellite retrievals of NO2 and HCHO. Although satellite retrievals have strongly improved over the last decades, there is still a need to better understand and reduce the uncertainties associated with every retrieval step of satellite data products, such as the AMF calculation. Here we compare and evaluate the different approaches used to calculate AMFs by several scientific groups (KNMI (WUR), IASB-BIRA, IUP-UNI. BREMEN, MPI-C, NASA GSFC, LEICESTER UNI. and PEKING UNI.). Each group calculated altitude dependent (box-) AMFs and clear sky and total tropospheric AMFs for several OMI orbits. First, European groups computed AMFs for one OMI orbit using common settings for the choice of surface albedo data, terrain height, cloud treatment and a priori vertical profile. Second, every group computed AMFs for two complete days in different seasons using preferred settings for the ancillary data and cloud treatment as a part of a Round Robin exercise. Box-AMFs comparison showed good consistency and underlined the importance of a correct treatment of the physical processes affecting the effective light path and the vertical discretization of the atmosphere. Using common settings, tropospheric NO2 AMFs in polluted pixels on average agreed within 4.7% whereas in remote pixels agreed within 3.5%. Using preferred settings relative differences between AMFs increase up to 15-30%. This increase is traced back to the different choices and assumptions made throughout the AMF calculation, which affect the final AMF values and thus the uncertainty in the AMF calculation. Differences between state of the art cloud treatment approaches highlight the importance of an accurate cloud correction: total and clear sky AMFs in polluted conditions differ by up to 40% depending on the retrieval scenario. Based on the comparison results, specific recommendations on best

  16. Release of PCDD/PCDF to air and land during open burning of sugarcane and forest litter over soil fortified with mass labelled PCDD/PCDF

    NASA Astrophysics Data System (ADS)

    Black, Robert R.; (Mick) Meyer, Carl P.; Yates, Alan; Van Zwieten, Lukas; Chittim, Brock G.; Mueller, Jochen F.

    2012-11-01

    The contribution of PCDD/PCDF emissions from soil during open burning of biomass was examined. Mass labelled PCDD/PCDF was added to soil containing native PCDD/PCDF and biomass was laid out on this soil and burnt, simulating sugarcane trash and forest fires. Smoke samples were collected using a high volume portable field sampler. After each fire the concentration of all mass labelled PCDD/PCDF congeners in the surface soil decreased, however, the concentration of some native 2,3,7,8 substituted congeners increased, indicating that formation was occurring. Mass labelled PCDD/PCDF congeners were detected in all ash samples, mean 2.8 pg g-1 (range 0.5-8 pg g-1), demonstrating release from the soil. Additionally, mass labelled PCDD/PCDF congeners were detected in all air samples mean 1.2 μg (t fuel)-1 (range 0.2-2.0 μg (t fuel)-1), again demonstrating release from the soil. Native 2,3,7,8 substituted congeners detected in the air samples were dominated (in terms of contribution to total congener mass) by Cl8DD (90% for forest litter and 77% for sugarcane). The major contributor to TEQ of emissions from both forest litter and sugarcane was 1, 2, 3, 7, 8-Cl5DD (40-64% and 57-75%, respectively). These results demonstrate that release of PCDD/PCDF from soil to air and land occurs during open burning of biomass when soil temperatures are sufficiently elevated.

  17. Ballistic projectile trajectory determining system

    DOEpatents

    Karr, T.J.

    1997-05-20

    A computer controlled system determines the three-dimensional trajectory of a ballistic projectile. To initialize the system, predictions of state parameters for a ballistic projectile are received at an estimator. The estimator uses the predictions of the state parameters to estimate first trajectory characteristics of the ballistic projectile. A single stationary monocular sensor then observes the actual first trajectory characteristics of the ballistic projectile. A comparator generates an error value related to the predicted state parameters by comparing the estimated first trajectory characteristics of the ballistic projectile with the observed first trajectory characteristics of the ballistic projectile. If the error value is equal to or greater than a selected limit, the predictions of the state parameters are adjusted. New estimates for the trajectory characteristics of the ballistic projectile are made and are then compared with actual observed trajectory characteristics. This process is repeated until the error value is less than the selected limit. Once the error value is less than the selected limit, a calculator calculates trajectory characteristics such a the origin and destination of the ballistic projectile. 8 figs.

  18. Ballistic projectile trajectory determining system

    DOEpatents

    Karr, Thomas J.

    1997-01-01

    A computer controlled system determines the three-dimensional trajectory of a ballistic projectile. To initialize the system, predictions of state parameters for a ballistic projectile are received at an estimator. The estimator uses the predictions of the state parameters to estimate first trajectory characteristics of the ballistic projectile. A single stationary monocular sensor then observes the actual first trajectory characteristics of the ballistic projectile. A comparator generates an error value related to the predicted state parameters by comparing the estimated first trajectory characteristics of the ballistic projectile with the observed first trajectory characteristics of the ballistic projectile. If the error value is equal to or greater than a selected limit, the predictions of the state parameters are adjusted. New estimates for the trajectory characteristics of the ballistic projectile are made and are then compared with actual observed trajectory characteristics. This process is repeated until the error value is less than the selected limit. Once the error value is less than the selected limit, a calculator calculates trajectory characteristics such a the origin and destination of the ballistic projectile.

  19. Trajectory optimization and guidance for an aerospace plane

    NASA Technical Reports Server (NTRS)

    Mease, Kenneth D.; Vanburen, Mark A.

    1989-01-01

    The first step in the approach to developing guidance laws for a horizontal take-off, air breathing single-stage-to-orbit vehicle is to characterize the minimum-fuel ascent trajectories. The capability to generate constrained, minimum fuel ascent trajectories for a single-stage-to-orbit vehicle was developed. A key component of this capability is the general purpose trajectory optimization program OTIS. The pre-production version, OTIS 0.96 was installed and run on a Convex C-1. A propulsion model was developed covering the entire flight envelope of a single-stage-to-orbit vehicle. Three separate propulsion modes, corresponding to an after burning turbojet, a ramjet and a scramjet, are used in the air breathing propulsion phase. The Generic Hypersonic Aerodynamic Model Example aerodynamic model of a hypersonic air breathing single-stage-to-orbit vehicle was obtained and implemented. Preliminary results pertaining to the effects of variations in acceleration constraints, available thrust level and fuel specific impulse on the shape of the minimum-fuel ascent trajectories were obtained. The results show that, if the air breathing engines are sized for acceleration to orbital velocity, it is the acceleration constraint rather than the dynamic pressure constraint that is active during ascent.

  20. On the Trajectories of Projectiles Depicted in Early Ballistic Woodcuts

    ERIC Educational Resources Information Center

    Stewart, Sean M.

    2012-01-01

    Motivated by quaint woodcut depictions often found in many late 16th and 17th century ballistic manuals of cannonballs fired in air, a comparison of their shapes with those calculated for the classic case of a projectile moving in a linear resisting medium is made. In considering the asymmetrical nature of such trajectories, the initial launch…

  1. Lunar Cube Transfer Trajectory Options

    NASA Technical Reports Server (NTRS)

    Folta, David; Dichmann, Donald J.; Clark, Pamela; Haapala, Amanda; Howell, Kathleen

    2015-01-01

    Numerous Earth-Moon trajectory and lunar orbit options are available for Cubesat missions. Given the limited Cubesat injection infrastructure, transfer trajectories are contingent upon the modification of an initial condition of the injected or deployed orbit. Additionally, these transfers can be restricted by the selection or designs of Cubesat subsystems such as propulsion or communication. Nonetheless, many trajectory options can be considered which have a wide range of transfer durations, fuel requirements, and final destinations. Our investigation of potential trajectories highlights several options including deployment from low Earth orbit (LEO), geostationary transfer orbits (GTO), and higher energy direct lunar transfers and the use of longer duration Earth-Moon dynamical systems. For missions with an intended lunar orbit, much of the design process is spent optimizing a ballistic capture while other science locations such as Sun-Earth libration or heliocentric orbits may simply require a reduced Delta-V imparted at a convenient location along the trajectory.

  2. Lunar Cube Transfer Trajectory Options

    NASA Technical Reports Server (NTRS)

    Folta, David; Dichmann, Donald James; Clark, Pamela E.; Haapala, Amanda; Howell, Kathleen

    2015-01-01

    Numerous Earth-Moon trajectory and lunar orbit options are available for Cubesat missions. Given the limited Cubesat injection infrastructure, transfer trajectories are contingent upon the modification of an initial condition of the injected or deployed orbit. Additionally, these transfers can be restricted by the selection or designs of Cubesat subsystems such as propulsion or communication. Nonetheless, many trajectory options can b e considered which have a wide range of transfer duration, fuel requirements, and final destinations. Our investigation of potential trajectories highlights several options including deployment from low Earth orbit (LEO) geostationary transfer orbits (GTO) and higher energy direct lunar transfer and the use of longer duration Earth-Moon dynamical systems. For missions with an intended lunar orbit, much of the design process is spent optimizing a ballistic capture while other science locations such as Sun-Earth libration or heliocentric orbits may simply require a reduced Delta-V imparted at a convenient location along the trajectory.

  3. Optimal solar sail planetocentric trajectories

    NASA Technical Reports Server (NTRS)

    Sackett, L. L.

    1977-01-01

    The analysis of solar sail planetocentric optimal trajectory problem is described. A computer program was produced to calculate optimal trajectories for a limited performance analysis. A square sail model is included and some consideration is given to a heliogyro sail model. Orbit to a subescape point and orbit to orbit transfer are considered. Trajectories about the four inner planets can be calculated and shadowing, oblateness, and solar motion may be included. Equinoctial orbital elements are used to avoid the classical singularities, and the method of averaging is applied to increase computational speed. Solution of the two-point boundary value problem which arises from the application of optimization theory is accomplished with a Newton procedure. Time optimal trajectories are emphasized, but a penalty function has been considered to prevent trajectories which intersect a planet's surface.

  4. Four-body trajectory optimization

    NASA Technical Reports Server (NTRS)

    Pu, C. L.; Edelbaum, T. N.

    1974-01-01

    A comprehensive optimization program has been developed for computing fuel-optimal trajectories between the earth and a point in the sun-earth-moon system. It presents methods for generating fuel optimal two-impulse trajectories which may originate at the earth or a point in space and fuel optimal three-impulse trajectories between two points in space. The extrapolation of the state vector and the computation of the state transition matrix are accomplished by the Stumpff-Weiss method. The cost and constraint gradients are computed analytically in terms of the terminal state and the state transition matrix. The 4-body Lambert problem is solved by using the Newton-Raphson method. An accelerated gradient projection method is used to optimize a 2-impulse trajectory with terminal constraint. The Davidon's Variance Method is used both in the accelerated gradient projection method and the outer loop of a 3-impulse trajectory optimization problem.

  5. Operational Use of the AIRS Total Column Ozone Retrievals Along with the RGB Air Mass Product as Part of the GOES-R Proving Ground

    NASA Technical Reports Server (NTRS)

    Folmer, Michael; Zavodsky, Bradley; Molthan, Andrew

    2012-01-01

    The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Prediction (NCEP) Hydrometeorological Prediction Center (HPC) and Ocean Prediction Center (OPC) provide short-term and medium-range forecast guidance of heavy precipitation, strong winds, and other features often associated with mid-latitude cyclones over both land and ocean. As a result, detection of factors that lead to rapid cyclogenesis and high wind events is key to improving forecast skill. One phenomenon that has been identified with these events is the stratospheric intrusion that occurs near tropopause folds. This allows for deep mixing near the top of the atmosphere where dry air high in ozone concentrations and potential vorticity descends (sometimes rapidly) deep into the mid-troposphere. Observations from satellites can aid in detection of these stratospheric air intrusions (SAI) regions. Specifically, multispectral composite imagery assign a variety of satellite spectral bands to the red, green, and blue (RGB) color components of imagery pixels and result in color combinations that can assist in the detection of dry stratospheric air associated with PV advection, which in turn may alert forecasters to the possibility of a rapidly strengthening storm system. Single channel or RGB satellite imagery lacks quantitative information about atmospheric moisture unless the sampled brightness temperatures or other data are converted to estimates of moisture via a retrieval process. Thus, complementary satellite observations are needed to capture a complete picture of a developing storm system. Here, total column ozone retrievals derived from a hyperspectral sounder are used to confirm the extent and magnitude of SAIs. Total ozone is a good proxy for defining locations and intensity of SAIs and has been used in studies evaluating that phenomenon (e.g. Tian et al. 2007, Knox and Schmidt 2005). Steep gradients in values of total ozone seen by satellites have been linked

  6. Mass spectrometry and inhomogeneous ion optics

    NASA Technical Reports Server (NTRS)

    White, F. A.

    1973-01-01

    Work done in several areas to advance the state of the art of magnetic mass spectrometers is described. The calculations and data necessary for the design of inhomogeneous field mass spectrometers, and the calculation of ion trajectories through such fields are presented. The development and testing of solid state ion detection devices providing the capability of counting single ions is discussed. New techniques in the preparation and operation of thermal-ionization ion sources are described. Data obtained on the concentrations of copper in rainfall and uranium in air samples using the improved thermal ionization techniques are presented. The design of a closed system static mass spectrometer for isotopic analyses is discussed. A summary of instrumental aspects of a four-stage mass spectrometer comprising two electrostatic and two 90 deg. magnetic lenses with a 122-cm radius used to study the interaction of ions with solids is presented.

  7. Sensitivities of Lagrangian modelling of mid-latitude cirrus clouds to trajectory data quality

    NASA Astrophysics Data System (ADS)

    Kienast-Sjögren, E.; Miltenberger, A. K.; Luo, B. P.; Peter, T.

    2015-07-01

    Simulations of cirrus are subject to uncertainties in model physics and meteorological input data. Here we model cirrus clouds along air mass trajectories, whose extinction has been measured with an elastic backscatter lidar at Jungfraujoch research station in the Swiss Alps, with a microphysical stacked box model. The sensitivities of these simulations to input data uncertainties (trajectory resolution, unresolved vertical velocities, ice nuclei number density and upstream specific humidity) are investigated. Variations in the temporal resolution of the wind field data (COSMO-Model at 2.2 km resolution) between 20 s and 1 h have only a marginal impact on the trajectory path, while the representation of the vertical velocity variability and therefore the cooling rate distribution are significantly affected. A temporal resolution better than 5 min must be chosen in order to resolve cooling rates required to explain the measured extinction. A further increase in the temporal resolution improves the simulation results slightly. The close match between the modelled and observed extinction profile for high-resolution trajectories suggests that the cooling rate spectra calculated by the COSMO-2 model suffice on the selected day. The modelled cooling rate spectra are, however, characterized by significantly lower vertical velocity amplitudes than those found previously in some aircraft campaigns (SUCCESS, MACPEX). A climatological analysis of the vertical velocity amplitude in the Alpine region based on COSMO-2 analyses and balloon sounding data suggests large day-to-day variability in small-scale temperature fluctuations. This demonstrates the necessity to apply numerical weather prediction models with high spatial and temporal resolutions in cirrus modelling, whereas using climatological means for the amplitude of the unresolved air motions does generally not suffice. The box model simulations further suggest that uncertainties in the upstream specific humidity (± 10

  8. Source assessment of particulate air pollutants measured at the southwest european coast

    NASA Astrophysics Data System (ADS)

    Pio, Casimiro A.; Castro, Luis M.; Cerqueira, Mario A.; Santos, Isabel M.; Belchior, Filipa; Salgueiro, Maria L.

    Aerosol particles and gaseous species were measured in air masses transported to the west coast of Portugal, between November 1993 and August 1994. Samples were taken during four monitoring campaigns distributed along the various seasons of the year, integrated in the EC Project: BMCAPE. Aerosol particles were collected with separation in two size fractions and analysed in relation to total mass, water soluble ions, trace elements and black/organic carbon. Local micro-meteorological parameters and air mass backward trajectories were compared with analytical results in order to define characteristic air mass types and to evaluate the origin of pollutants. Average concentrations on the Portuguese west coast, even in maritime air masses, are higher than values observed in remote oceanic locations. This is probably a consequence of continental European air masses recirculation through the eastern Atlantic Ocean, reinforced by situations of mesoscale transport from the Iberian Peninsula. Principal Component Analysis permitted the identification of five source groups for the fine and coarse aerosol fractions, namely combustion plus road traffic, sea salt spray, secondary aerosol production, soil and possibly non-ferrous metallurgy industries. In the aerosol fine fraction road traffic and combustion contribute on average with 25% of the total fine aerosol mass, while sea spray and secondary production represent 14% and 31%, respectively of the mass loading. Sea spray is by far the major contributor to the coarse fraction with an average of 88% of the suspended coarse aerosol mass.

  9. A Final Approach Trajectory Model for Current Operations

    NASA Technical Reports Server (NTRS)

    Gong, Chester; Sadovsky, Alexander

    2010-01-01

    Predicting accurate trajectories with limited intent information is a challenge faced by air traffic management decision support tools in operation today. One such tool is the FAA's Terminal Proximity Alert system which is intended to assist controllers in maintaining safe separation of arrival aircraft during final approach. In an effort to improve the performance of such tools, two final approach trajectory models are proposed; one based on polynomial interpolation, the other on the Fourier transform. These models were tested against actual traffic data and used to study effects of the key final approach trajectory modeling parameters of wind, aircraft type, and weight class, on trajectory prediction accuracy. Using only the limited intent data available to today's ATM system, both the polynomial interpolation and Fourier transform models showed improved trajectory prediction accuracy over a baseline dead reckoning model. Analysis of actual arrival traffic showed that this improved trajectory prediction accuracy leads to improved inter-arrival separation prediction accuracy for longer look ahead times. The difference in mean inter-arrival separation prediction error between the Fourier transform and dead reckoning models was 0.2 nmi for a look ahead time of 120 sec, a 33 percent improvement, with a corresponding 32 percent improvement in standard deviation.

  10. Survey and Method for Determination of Trajectory Predictor Requirements

    NASA Technical Reports Server (NTRS)

    Rentas, Tamika L.; Green, Steven M.; Cate, Karen Tung

    2009-01-01

    A survey of air-traffic-management researchers, representing a broad range of automation applications, was conducted to document trajectory-predictor requirements for future decision-support systems. Results indicated that the researchers were unable to articulate a basic set of trajectory-prediction requirements for their automation concepts. Survey responses showed the need to establish a process to help developers determine the trajectory-predictor-performance requirements for their concepts. Two methods for determining trajectory-predictor requirements are introduced. A fast-time simulation method is discussed that captures the sensitivity of a concept to the performance of its trajectory-prediction capability. A characterization method is proposed to provide quicker, yet less precise results, based on analysis and simulation to characterize the trajectory-prediction errors associated with key modeling options for a specific concept. Concept developers can then identify the relative sizes of errors associated with key modeling options, and qualitatively determine which options lead to significant errors. The characterization method is demonstrated for a case study involving future airport surface traffic management automation. Of the top four sources of error, results indicated that the error associated with accelerations to and from turn speeds was unacceptable, the error associated with the turn path model was acceptable, and the error associated with taxi-speed estimation was of concern and needed a higher fidelity concept simulation to obtain a more precise result

  11. Fractional trajectories: Decorrelation versus friction

    NASA Astrophysics Data System (ADS)

    Svenkeson, A.; Beig, M. T.; Turalska, M.; West, B. J.; Grigolini, P.

    2013-11-01

    The fundamental connection between fractional calculus and subordination processes is explored and affords a physical interpretation of a fractional trajectory, that being an average over an ensemble of stochastic trajectories. Heretofore what has been interpreted as intrinsic friction, a form of non-Markovian dissipation that automatically arises from adopting the fractional calculus, is shown to be a manifestation of decorrelations between trajectories. We apply the general theory developed herein to the Lotka-Volterra ecological model, providing new insight into the final equilibrium state. The relaxation time to achieve this state is also considered.

  12. Highly sensitive determination of polycyclic aromatic hydrocarbons in ambient air dust by gas chromatography-mass spectrometry after molecularly imprinted polymer extraction.

    PubMed

    Krupadam, Reddithota J; Bhagat, Bhagyashree; Khan, Muntazir S

    2010-08-01

    A method based on solid--phase extraction with a molecularly imprinted polymer (MIP) has been developed to determine five probable human carcinogenic polycyclic aromatic hydrocarbons (PAHs) in ambient air dust by gas chromatography-mass spectrometry (GC-MS). Molecularly imprinted poly(vinylpyridine-co-ethylene glycol dimethacrylate) was chosen as solid-phase extraction (SPE) material for PAHs. The conditions affecting extraction efficiency, for example surface properties, concentration of PAHs, and equilibration times were evaluated and optimized. Under optimum conditions, pre-concentration factors for MIP-SPE ranged between 80 and 93 for 10 mL ambient air dust leachate. PAHs recoveries from MIP-SPE after extraction from air dust were between 85% and 97% and calibration graphs of the PAHs showed a good linearity between 10 and 1000 ng L(-1) (r = 0.99). The extraction efficiency of MIP for PAHs was compared with that of commercially available SPE materials--powdered activated carbon (PAC) and polystyrene-divinylbenzene resin (XAD)--and it was shown that the extraction capacity of the MIP was better than that of the other two SPE materials. Organic matter in air dust had no effect on MIP extraction, which produced a clean extract for GC-MS analysis. The detection limit of the method proposed in this article is 0.15 ng L(-1) for benzo[a]pyrene, which is a marker molecule of air pollution. The method has been applied to the determination of probable carcinogenic PAHs in air dust of industrial zones and satisfactory results were obtained.

  13. The Use of Red Green Blue Air Mass Imagery to Investigate the Role of Stratospheric Air in a Non-convective Wind Event

    NASA Technical Reports Server (NTRS)

    Berndt, E. B.; Zavodsky, B. T.; Jedlovec, G. J.; Molthan, A. L.

    2013-01-01

    Non-convective wind events commonly occur with passing extratropical cyclones and have significant societal and economic impacts. Since non-convective winds often occur in the absence of specific phenomena such as a thunderstorm, tornado, or hurricane, the public are less likely to heed high wind warnings and continue daily activities. Thus non-convective wind events result in as many fatalities as straight line thunderstorm winds. One physical explanation for non-convective winds includes tropopause folds. Improved model representation of stratospheric air and associated non-convective wind events could improve non-convective wind forecasts and associated warnings. In recent years, satellite data assimilation has improved skill in forecasting extratropical cyclones; however errors still remain in forecasting the position and strength of extratropical cyclones as well as the tropopause folding process. The goal of this study is to determine the impact of assimilating satellite temperature and moisture retrieved profiles from hyperspectral infrared (IR) sounders (i.e. Atmospheric Infrared Sounder (AIRS), Cross-track Infrared and Microwave Sounding Suite (CrIMSS), and Infrared Atmospheric Sounding Interferometer (IASI)) on the model representation of the tropopause fold and an associated high wind event that impacted the Northeast United States on 09 February 2013. Model simulations using the Advanced Research Weather Research and Forecasting Model (ARW) were conducted on a 12-km grid with cycled data assimilation mimicking the operational North American Model (NAM). The results from the satellite assimilation run are compared to a control experiment (without hyperspectral IR retrievals), Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis, and Rapid Refresh analyses.

  14. High-precision measurements of mercury vapor in air: Design of a six-port-manifold mass flow controller system and evaluation of mass flow errors at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Kim, Ki-Hyun; Lindberg, Steven E.

    1994-03-01

    We constructed an atmospheric sampling system for Hg vapor that utilizes a single vacuum pump connected via a manifold to six separate mass flow controllers (MFC). The manifold system reduces the size and power requirements for collection of replicate samples, is ideally suited for use on meteorological towers, and achieves the precise control of air-sampling volumes required for computing air/surface exchange rates from concentration gradients of Hg vapor. In testing our air sampling systems, we found consistent calibration errors between the manufacturer's calibrations and a standard bubble flow meter. Errors as high as 30% decreased systematically with increasing flow rate to values of 3-5% at near-maximum flow. The relative error patterns established between adjacent MFC units in each system were found to be relatively stable over time. Using gold-coated sand amalgamation traps for Hg vapor and the flow correction factors computed from our calibrations, we routinely achieve precision for replicate measurements of Hg vapor in background air of 0.5-2% (expressed as relative standard errors of mean concentrations of 1.5-3.5 ng/m3). Application of the flow correction factors measurably decreases the level of bias between mean concentrations of Hg vapor measured with adjacent sampling systems and is necessary to reduce uncertainty associated with quantifying gradients in atmospheric concentrations.

  15. Numerical investigation of interfacial mass transport resistance and two-phase flow in PEM fuel cell air channels

    NASA Astrophysics Data System (ADS)

    Koz, Mustafa

    Proton exchange membrane fuel cells (PEMFCs) are efficient and environmentally friendly electrochemical engines. The performance of a PEMFC is adversely affected by oxygen (O2) concentration loss from the air flow channel to the cathode catalyst layer (CL). Oxygen transport resistance at the gas diffusion layer (GDL) and air channel interface is a non-negligible component of the O2 concentration loss. Simplified PEMFC performance models in the available literature incorporate the O2 resistance at the GDL-channel interface as an input parameter. However, this parameter has been taken as a constant so far in the available literature and does not reflect variable PEMFC operating conditions and the effect of two-phase flow in the channels. This study numerically calculates the O2 transport resistance at the GDL-air channel interface and expresses this resistance through the non-dimensional Sherwood number (Sh). Local Sh is investigated in an air channel with multiple droplets and films inside. These water features are represented as solid obstructions and only air flow is simulated. Local variations of Sh in the flow direction are obtained as a function of superficial air velocity, water feature size, and uniform spacing between water features. These variations are expressed with mathematical expressions for the PEMFC performance models to utilize and save computational resources. The resulting mathematical correlations for Sh can be utilized in PEMFC performance models. These models can predict cell performance more accurately with the help of the results of this work. Moreover, PEMFC performance models do not need to use a look-up table since the results were expressed through correlations. Performance models can be kept simplified although their predictions will become more realistic. Since two-phase flow in channels is experienced mostly at lower temperatures, performance optimization at low temperatures can be done easier.

  16. Sensitive and comprehensive detection of chemical warfare agents in air by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow introduction.

    PubMed

    Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Yamashiro, Shigeharu; Sano, Yasuhiro; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Sekiguchi, Hiroyuki; Iura, Kazumitsu; Nagashima, Hisayuki; Nagoya, Tomoki; Tsuge, Kouichiro; Ohsawa, Isaac; Okumura, Akihiko; Takada, Yasuaki; Ezawa, Naoya; Watanabe, Susumu; Hashimoto, Hiroaki

    2014-05-01

    A highly sensitive and specific real-time field-deployable detection technology, based on counterflow air introduction atmospheric pressure chemical ionization, has been developed for a wide range of chemical warfare agents (CWAs) comprising gaseous (two blood agents, three choking agents), volatile (six nerve gases and one precursor agent, five blister agents), and nonvolatile (three lachrymators, three vomiting agents) agents in air. The approach can afford effective chemical ionization, in both positive and negative ion modes, for ion trap multiple-stage mass spectrometry (MS(n)). The volatile and nonvolatile CWAs tested provided characteristic ions, which were fragmented into MS(3) product ions in positive and negative ion modes. Portions of the fragment ions were assigned by laboratory hybrid mass spectrometry (MS) composed of linear ion trap and high-resolution mass spectrometers. Gaseous agents were detected by MS or MS(2) in negative ion mode. The limits of detection for a 1 s measurement were typically at or below the microgram per cubic meter level except for chloropicrin (submilligram per cubic meter). Matrix effects by gasoline vapor resulted in minimal false-positive signals for all the CWAs and some signal suppression in the case of mustard gas. The moisture level did influence the measurement of the CWAs.

  17. Sensitive and comprehensive detection of chemical warfare agents in air by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow introduction.

    PubMed

    Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Yamashiro, Shigeharu; Sano, Yasuhiro; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Sekiguchi, Hiroyuki; Iura, Kazumitsu; Nagashima, Hisayuki; Nagoya, Tomoki; Tsuge, Kouichiro; Ohsawa, Isaac; Okumura, Akihiko; Takada, Yasuaki; Ezawa, Naoya; Watanabe, Susumu; Hashimoto, Hiroaki

    2014-05-01

    A highly sensitive and specific real-time field-deployable detection technology, based on counterflow air introduction atmospheric pressure chemical ionization, has been developed for a wide range of chemical warfare agents (CWAs) comprising gaseous (two blood agents, three choking agents), volatile (six nerve gases and one precursor agent, five blister agents), and nonvolatile (three lachrymators, three vomiting agents) agents in air. The approach can afford effective chemical ionization, in both positive and negative ion modes, for ion trap multiple-stage mass spectrometry (MS(n)). The volatile and nonvolatile CWAs tested provided characteristic ions, which were fragmented into MS(3) product ions in positive and negative ion modes. Portions of the fragment ions were assigned by laboratory hybrid mass spectrometry (MS) composed of linear ion trap and high-resolution mass spectrometers. Gaseous agents were detected by MS or MS(2) in negative ion mode. The limits of detection for a 1 s measurement were typically at or below the microgram per cubic meter level except for chloropicrin (submilligram per cubic meter). Matrix effects by gasoline vapor resulted in minimal false-positive signals for all the CWAs and some signal suppression in the case of mustard gas. The moisture level did influence the measurement of the CWAs. PMID:24678766

  18. Seasonal, anthropogenic, air mass, and meteorological influences on the atmospheric concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs): Evidence for the importance of diffuse combustion sources

    SciTech Connect

    Lee, R.G.M.; Green, N.J.L.; Lohmann, R.; Jones, K.C.

    1999-09-01

    Sampling programs were undertaken to establish air polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) concentrations at a semirural site on the northwest coast of England in autumn and summer and to investigate factors causing their variability. Changing source inputs, meteorological parameters, air masses, and the impact of a festival when it is customary to light fireworks and bonfires were investigated. Various lines of evidence from the study point to diffuse, combustion-related sources being a major influence on ambient air concentrations. Higher PCDD/F concentrations were generally associated with air masses that had originated and moved over land, particularly during periods of low ambient temperature. Low concentrations were associated with air masses that had arrived from the Atlantic Ocean/Irish Sea to the west of the sampling site and had little or no contact with urban/industrialized areas. Concentrations in the autumn months were 2 to 10 times higher than those found in the summer.

  19. Theoretical study of the effect of liquid desiccant mass flow rate on the performance of a cross flow parallel-plate liquid desiccant-air dehumidifier

    NASA Astrophysics Data System (ADS)

    Mohammad, Abdulrahman Th.; Mat, Sohif Bin; Sulaiman, M. Y.; Sopian, K.; Al-abidi, Abduljalil A.

    2013-11-01

    A computer simulation using MATLAB is investigated to predict the distribution of air stream parameters (humidity ratio and temperature) as well as desiccant parameters (temperature and concentration) inside the parallel plate absorber. The present absorber consists of fourteen parallel plates with a surface area per unit volume ratio of 80 m2/m3. Calcium chloride as a liquid desiccant flows through the top of the plates to the bottom while the air flows through the gap between the plates making it a cross flow configuration. The model results show the effect of desiccant mass flow rate on the performance of the dehumidifier (moisture removal and dehumidifier effectiveness). Performance comparisons between present cross-flow dehumidifier and another experimental cross-flow dehumidifier in the literature are carried out. The simulation is expected to help in optimizing of a cross flow dehumidifier.

  20. Combustion of a Methane-Air Mixture in a Slot Burner with an Inert Insert in Mass Transfer to the Environment

    NASA Astrophysics Data System (ADS)

    Krainov, A. Yu.; Moiseeva, K. M.

    2016-03-01

    A problem on combustion of a methane-air mixture in a slot burner with an internal insert in mass transfer from the burner's exterior wall to the environment has been solved. A mathematical formulation of the problem takes account of the dependence of the diffusion, thermal-conductivity, and heat-transfer coefficients on temperature, and also of the heat removal from the gas to the environment by convective and radiant heat transfer. A numerical investigation has been carried out in a one-dimensional mathematical formulation of the problem in dimensional variables. The boundary of existence of a stable high-temperature regime of combustion of the methane-air mixture has been determined as a function of the rate of feed of the gas, the environmental temperature, and the width of the flow area of the burner.

  1. Determination of seven pyrethroids biocides and their synergist in indoor air by thermal-desorption gas chromatography/mass spectrometry after sampling on Tenax TA ® passive tubes.

    PubMed

    Raeppel, Caroline; Appenzeller, Brice M; Millet, Maurice

    2015-01-01

    A method coupling thermal desorption and gas chromatography/mass spectrometry (GC/MS) was developed for the simultaneous determination of 7 pyrethroids (allethrin, bifenthrin, cyphenothrin, imiprothrin, permethrin, prallethrin and tetramethrin) and piperonyl butoxide adsorbed on Tenax TA(®) passive samplers after exposure in indoor air. Thermal desorption was selected as it permits efficient and rapid extraction without solvent used together with a good sensitivity. Detection (S/N>3) and quantification (S/N>10) limits varied between 0.001 ng and 2.5 ng and between 0.005 and 10 ng respectively with a reproducibility varied between 14% (bifenthrin) and 39% (permethrin). The method was used for the comparison indoor air contamination after low-pressure spraying and fumigation application in a rubbish chute situated in the basement of a building.

  2. Galileo's Trajectory with Mild Resistance

    ERIC Educational Resources Information Center

    Groetsch, C. W.

    2012-01-01

    An aspect of Galileo's classical trajectory that persists in a simple resistance model is noted. The resistive model provides a case study for the classroom analysis of limiting behaviour of an implicitly defined function. (Contains 1 note.)

  3. Monitoring of Hazardous Air Pollutant Surrogates Using Resonance Enhanced Multiphoton Ionization/Time of Flight Mass Spectrometry

    EPA Science Inventory

    EPA’s preferred approach for regulatory emissions compliance is based upon real-time monitoring of individual hazardous air pollutants (HAPs). Real-time, continuous monitoring not only provides the most comprehensive assurance of emissions compliance, but also can serve as...

  4. Determination of Hazardous Air Pollutant Surrogates Using Resonance Enhanced Multi Photon Ionization - Time of Flight Mass Spectrometry

    EPA Science Inventory

    EPA?s preferred approach for regulatory emissions compliance is based upon real-time monitoring of individual hazardous air pollutants (HAPs). Real-time, continuous monitoring not only provides the most comprehensive assurance of emissions compliance, but also can serve as a pro...

  5. Fast three-dimensional k-space trajectory design using missile guidance ideas.

    PubMed

    Mir, Roberto; Guesalaga, Andres; Spiniak, Juan; Guarini, Marcelo; Irarrazaval, Pablo

    2004-08-01

    Three-dimensional (3D) k-space trajectories are needed to acquire volumetric images in MRI. While scan time is determined by the trajectory efficiency, image quality and distortions depend on the shape of the trajectories. There are several 3D trajectory strategies for sampling the k-space using rectilinear or curve schemes. Since there is no evidence about their optimality in terms of image quality and acquisition time, a new design method based on missile guidance ideas is explored. Since air-to-air missile guidance shares similar goals and constraints with the problem of k-space trajectory design, a control approach for missiles is used to design a 3D trajectory. The k-space is divided into small cubes, and each one is treated as a target to be sampled. The main goal is to cover the entire space as quickly and efficiently as possible, with good performance under different conditions. This novel design method is compared to other trajectories using simulated and real data. As an example, a trajectory that requires 0.11 times the number of shots needed by the cylindrical 3DFT acquisition was designed. This trajectory requires more shots (1.66 times) than the stack of spirals, but behaves better under nonideal conditions, such as off-resonance and motion.

  6. Simulation of heat and mass transfer processes in the experimental section of the air-condensing unit of Scientific Production Company "Turbocon"

    NASA Astrophysics Data System (ADS)

    Artemov, V. I.; Minko, K. B.; Yan'kov, G. G.; Kiryukhin, A. V.

    2016-05-01

    A mathematical model was developed to be used for numerical analysis of heat and mass transfer processes in the experimental section of the air condenser (ESAC) created in the Scientific Production Company (SPC) "Turbocon" and mounted on the territory of the All-Russia Thermal Engineering Institute. The simulations were performed using the author's CFD code ANES. The verification of the models was carried out involving the experimental data obtained in the tests of ESAC. The operational capability of the proposed models to calculate the processes in steam-air mixture and cooling air and algorithms to take into account the maldistribution in the various rows of tube bundle was shown. Data on the influence of temperature and flow rate of the cooling air on the pressure in the upper header of ESAC, effective heat transfer coefficient, steam flow distribution by tube rows, and the dimensions of the ineffectively operating zones of tube bundle for two schemes of steam-air mixture flow (one-pass and two-pass ones) were presented. It was shown that the pressure behind the turbine (in the upper header) increases significantly at increase of the steam flow rate and reduction of the flow rate of cooling air and its temperature rise, and the maximum value of heat transfer coefficient is fully determined by the flow rate of cooling air. Furthermore, the steam flow rate corresponding to the maximum value of heat transfer coefficient substantially depends on the ambient temperature. The analysis of the effectiveness of the considered schemes of internal coolant flow was carried out, which showed that the two-pass scheme is more effective because it provides lower pressure in the upper header, despite the fact that its hydraulic resistance at fixed flow rate of steam-air mixture is considerably higher than at using the one-pass schema. This result is a consequence of the fact that, in the two-pass scheme, the condensation process involves the larger internal surface of tubes

  7. Four-body trajectory optimization

    NASA Technical Reports Server (NTRS)

    Pu, C. L.; Edelbaum, T. N.

    1973-01-01

    A collection of typical three-body trajectories from the L1 libration point on the sun-earth line to the earth is presented. These trajectories in the sun-earth system are grouped into four distinct families which differ in transfer time and delta V requirements. Curves showing the variations of delta V with respect to transfer time, and typical two and three-impulse primer vector histories, are included. The development of a four-body trajectory optimization program to compute fuel optimal trajectories between the earth and a point in the sun-earth-moon system are also discussed. Methods for generating fuel optimal two-impulse trajectories which originate at the earth or a point in space, and fuel optimal three-impulse trajectories between two points in space, are presented. A brief qualitative comparison of these methods is given. An example of a four-body two-impulse transfer from the Li libration point to the earth is included.

  8. Capture Conditions for Merging Trajectory Segments to Model Realistic Aircraft Descents

    NASA Technical Reports Server (NTRS)

    Zhao, Yiyuan; Slattery, Rhonda A.

    1996-01-01

    A typical commercial aircraft trajectory consists of a series of flight segments. An aircraft switches from one segment to another when certain specified variables reach their desired values. Trajectory synthesis for air traffic control automation must be consistent with practical pilot procedures. We examine capture conditions for merging trajectory segments to model commercial aircraft descent in trajectory synthesis. These conditions translate into bounds on measurements of atmospheric wind, pressure, and temperature. They also define ranges of thrust and drag feasible for a descent trajectory. Capture conditions are derived for the Center-TRACON Automation System developed at NASA Ames Research Center for automated air traffic control. Various uses of capture conditions are discussed. A Boeing 727-200 aircraft is used to provide numerical examples of capture conditions.

  9. Heat and mass transfer in a dissociated laminar boundary layer of air with consideration of the finite rate of chemical reaction

    NASA Technical Reports Server (NTRS)

    Oyegbesan, A. O.; Algermissen, J.

    1986-01-01

    A numerical investigation of heat and mass transfer in a dissociated laminar boundary layer of air on an isothermal flat plate is carried out for different degrees of cooling of the wall. A finite-difference chemical model is used to study elementary reactions involving NO2 and N2O. The analysis is based on equations of continuity, momentum, energy, conservation and state for the two-dimensional viscous flow of a reacting multicomponent mixtures. Attention is given to the effects of both catalyticity and noncatalyticity of the wall.

  10. Inter-annual variability of air mass and acidified pollutants transboundary exchange in the north-eastern part of the EANET region

    NASA Astrophysics Data System (ADS)

    Gromov, Sergey A.; Trifonova-Yakovleva, Alisa; Gromov, Sergey S.

    2016-04-01

    Anthropogenic emissions, be it exhaust gases or aerosols, stem from multitude of sources and may survive long-range transport within the air masses they were emitted into. So they follow regional and global transport pathways varying under different climatological regimes. Transboundary transfer of pollutants occurs this way and has a significant impact on the ecological situation of the territories neighbouring those of emission sources, as found in a few earlier studies examining the environmental monitoring data [1]. In this study, we employ a relatively facile though robust technique for estimating the transboundary air and concomitant pollutant fluxes using actual or climatological meteorological and air pollution monitoring data. Practically, we assume pollutant transfer being proportional to the horizontal transport of air enclosed in the lower troposphere and to the concentration of the pollutant of interest. The horizontal transport, in turn, is estimated using the mean layer wind direction and strength, or their descriptive statistics at the individual transects of the boundary of interest. The domain of our interest is the segment of Russian continental border in East Asia spanning from 88° E (southern Middle Siberia) to 135° E (Far East at Pacific shore). The data on atmospheric pollutants concentration are available from the Russian monitoring sites of the region-wide Acid Deposition Monitoring Network in East Asia (EANET, http://www.eanet.asia/) Mondy (Baikal area) and Primorskaya (near Vladivostok). The data comprises multi-year continuous measurement of gas-phase and particulate species abundances in air with at least biweekly sampling rate starting from 2000. In the first phase of our study, we used climatological dataset on winds derived from the aerological soundings at Russian stations along the continental border for the 10-year period (1961-1970) by the Research Institute of Hydrometeorological Information - World Data Centre (RIHMI-WDC) [3

  11. ASTP (SA-210) Launch vehicle operational flight trajectory. Part 3: Final documentation

    NASA Technical Reports Server (NTRS)

    Carter, A. B.; Klug, G. W.; Williams, N. W.

    1975-01-01

    Trajectory data are presented for a nominal and two launch window trajectory simulations. These trajectories are designed to insert a manned Apollo spacecraft into a 150/167 km. (81/90 n. mi.) earth orbit inclined at 51.78 degrees for rendezvous with a Soyuz spacecraft, which will be orbiting at approximately 225 km. (121.5 n. mi.). The launch window allocation defined for this launch is 500 pounds of S-IVB stage propellant. The launch window opening trajectory simulation depicts the earliest launch time deviation from a planar flight launch which conforms to this constraint. The launch window closing trajectory simulation was developed for the more stringent Air Force Eastern Test Range (AFETR) flight azimuth restriction of 37.4 degrees east-of-north. These trajectories enclose a 12.09 minute launch window, pertinent features of which are provided in a tabulation. Planar flight data are included for mid-window reference.

  12. Brownian relaxation of an inelastic sphere in air

    NASA Astrophysics Data System (ADS)

    Bird, G. A.

    2016-06-01

    The procedures that are used to calculate the forces and moments on an aerodynamic body in the rarefied gas of the upper atmosphere are applied to a small sphere of the size of an aerosol particle at sea level. While the gas-surface interaction model that provides accurate results for macroscopic bodies may not be appropriate for bodies that are comprised of only about a thousand atoms, it provides a limiting case that is more realistic than the elastic model. The paper concentrates on the transfer of energy from the air to an initially stationary sphere as it acquires Brownian motion. Individual particle trajectories vary wildly, but a clear relaxation process emerges from an ensemble average over tens of thousands of trajectories. The translational and rotational energies in equilibrium Brownian motion are determined. Empirical relationships are obtained for the mean translational and rotational relaxation times, the mean initial power input to the particle, the mean rates of energy transfer between the particle and air, and the diffusivity. These relationships are functions of the ratio of the particle mass to an average air molecule mass and the Knudsen number, which is the ratio of the mean free path in the air to the particle diameter. The ratio of the molecular radius to the particle radius also enters as a correction factor. The implications of Brownian relaxation for the second law of thermodynamics are discussed.

  13. Advanced launch system trajectory optimization using suboptimal control

    NASA Technical Reports Server (NTRS)

    Shaver, Douglas A.; Hull, David G.

    1993-01-01

    The maximum-final mass trajectory of a proposed configuration of the Advanced Launch System is presented. A model for the two-stage rocket is given; the optimal control problem is formulated as a parameter optimization problem; and the optimal trajectory is computed using a nonlinear programming code called VF02AD. Numerical results are presented for the controls (angle of attack and velocity roll angle) and the states. After the initial rotation, the angle of attack goes to a positive value to keep the trajectory as high as possible, returns to near zero to pass through the transonic regime and satisfy the dynamic pressure constraint, returns to a positive value to keep the trajectory high and to take advantage of minimum drag at positive angle of attack due to aerodynamic shading of the booster, and then rolls off to negative values to satisfy the constraints. Because the engines cannot be throttled, the maximum dynamic pressure occurs at a single point; there is no maximum dynamic pressure subarc. To test approximations for obtaining analytical solutions for guidance, two additional optimal trajectories are computed: one using untrimmed aerodynamics and one using no atmospheric effects except for the dynamic pressure constraint. It is concluded that untrimmed aerodynamics has a negligible effect on the optimal trajectory and that approximate optimal controls should be able to be obtained by treating atmospheric effects as perturbations.

  14. Regularities in hadron systematics, Regge trajectories and a string quark model.

    SciTech Connect

    Chekanov, S.; Levchenko, B.; High Energy Physics; Inst. of Nuclear Physics

    2007-01-01

    An empirical principle for the construction of a linear relationship between the total angular momentum and squared-mass of baryons is proposed. In order to examine linearity of the trajectories, a rigorous least-squares regression analysis was performed. Unlike the standard Regge-Chew-Frautschi approach, the constructed trajectories do not have nonlinear behavior. A similar regularity may exist for lowest-mass mesons. The linear baryonic trajectories are well described by a semiclassical picture based on a spinning relativistic string with tension. The obtained numerical solution of this model was used to extract the (di)quark masses.

  15. Regularities in hadron systematics, Regge trajectories and a string quark model

    SciTech Connect

    Chekanov, S. V.; Levchenko, B. B.

    2007-01-01

    An empirical principle for the construction of a linear relationship between the total angular momentum and squared-mass of baryons is proposed. In order to examine linearity of the trajectories, a rigorous least-squares regression analysis was performed. Unlike the standard Regge-Chew-Frautschi approach, the constructed trajectories do not have nonlinear behavior. A similar regularity may exist for lowest-mass mesons. The linear baryonic trajectories are well described by a semiclassical picture based on a spinning relativistic string with tension. The obtained numerical solution of this model was used to extract the (di)quark masses.

  16. Is PM(10) mass measurement a reliable index for air quality assessment? An environmental study in a geographical area of north-eastern Italy.

    PubMed

    Cozzi, F; Adami, G; Barbieri, P; Reisenhofer, E; Bovenzi, M

    2008-09-01

    The aim of this study was to measure the concentration of some metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Ti) in PM(10) samples collected in one urban and one industrial site and to assess that PM(10) total mass measurement may be not sufficient as air quality index due to its complex composition. Metals were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and differential pulsed anodic stripping voltammetry (DPASV). The measured concentrations were used to calculate the content of metals in the PM(10) total mass, and to estimate the enrichment factors and the correlations between PM(10), metal concentrations and meteorological data for the two sites. The mean PM10 concentration during the sampling period in the urban site exceeded the annual European Union (EU) standard (40 microg/m(3)) and, for some sampling days, the daily EU standard (50 microg/m(3)) was also exceeded. In opposite, both EU standards were never exceeded in the industrial site. The overall metal content was nearly double in the industrial site compared to the urban one, and the mean Ni concentration exceeded the EU annual limit value (10 ng/m(3)). The metals with the highest enrichment factor were Cd, Cu, Ni and Pb for both sites, suggesting a dominant anthropogenic source for these metals. Metal concentrations were very low and typical of rural background during Christmas holidays, when factories were closed. PM(10) total mass measurement is not a sufficient air quality index since the metal content of PM(10) is not related to its total mass, especially in sites with industrial activities. This measurement should be associated with the analysis of toxic metals.

  17. Closed form low-thrust trajectories for Mars missions

    SciTech Connect

    Purvis, J.W.

    1992-01-01

    Several closed form trajectory solutions have been developed for low-thrust interplanetary flight and used with patched conics for analysis of combined propulsion systems. The solutions provide insight into alternative types of Mars missions, and show considerable mass savings for fast crewed missions with outbound trip times on the order of 90--100 days. 7 refs.

  18. Closed form low-thrust trajectories for Mars missions

    SciTech Connect

    Purvis, J.W.

    1992-08-01

    Several closed form trajectory solutions have been developed for low-thrust interplanetary flight and used with patched conics for analysis of combined propulsion systems. The solutions provide insight into alternative types of Mars missions, and show considerable mass savings for fast crewed missions with outbound trip times on the order of 90--100 days. 7 refs.

  19. Sensitive indoor air monitoring of monoterpenes using different adsorbents and thermal desorption gas chromatography with mass-selective detection.

    PubMed

    Hollender, Juliane; Sandner, Frank; Möller, Manfred; Dott, Wolfgang

    2002-07-12

    A simple method using active trapping on adsorbents and thermal desorption followed by GC-MS analysis was developed for the indoor air monitoring of monoterpenes. The study was carried out using a dynamically generated atmosphere consisting of 11 monoterpenes: camphene, camphor, delta 3-carene, 1,8-cineol, limonene, linalool, alpha-pinene, beta-pinene, alpha-terpinene, gamma-terpinene, fenchyl alcohol. The influence of the different adsorbents Tenax TA, Tenax GR, Carbosieve SIII, Chromosorb 106 on the yield of six selected monoterpenes at indoor air concentrations was studied. The adsorbent Tenax GR gave relatively the best yields followed by Tenax TA. Detection limits of approximately 1 microgram m3 were determined with Tenax GR for most of the monoterpenes.

  20. Global Optimization of Low-Thrust Interplanetary Trajectories Subject to Operational Constraints

    NASA Technical Reports Server (NTRS)

    Englander, Jacob Aldo; Vavrina, Matthew; Hinckley, David

    2016-01-01

    Low-thrust electric propulsion provides many advantages for mission to difficult targets-Comets and asteroids-Mercury-Outer planets (with sufficient power supply)Low-thrust electric propulsion is characterized by high power requirements but also very high specific impulse (Isp), leading to very good mass fractions. Low-thrust trajectory design is a very different process from chemical trajectory.

  1. Highly constrained entry trajectory generation

    NASA Astrophysics Data System (ADS)

    Xie, Yu; Liu, Luhua; Tang, Guojian; Zheng, Wei

    2013-07-01

    An entry trajectory planning algorithm that generates flyable trajectories satisfying waypoints, no-fly zones, and other path and terminal constraints is presented. The algorithm tactically divides the entry trajectory into the initial and glide phases. In the initial phase, a nominal angle of attack and a constant bank angle are used to generate the 3-D trajectory. In the glide phase, a planner is developed based on the evolved acceleration guidance logic for entry (EAGLE). The planner is divided into a longitudinal sub-planner and a lateral sub-planner. For longitudinal planning, the drag-energy profile is represented as five piecewise linear functions of the normalized non-conventional energy to make it consistent with both the desired trajectory length and the lateral maneuverability required to meet waypoint and no-fly zone constraints. The longitudinal sub-planner determines the magnitude of the bank angle, whereas the lateral sub-planner determines the appropriate sign of the bank angle for passing waypoints, avoiding no-fly zones, and minimizing the final heading error. The longitudinal and lateral sub-planners are iteratively employed until all path and terminal constraints are satisfied. Then, a tracker is employed to follow both the reference drag acceleration and the heading angle profiles to generate a feasible closed-loop entry trajectory. The approach is tested using the Common Aero Vehicle model. Simulations demonstrate that the generated trajectories can pass the predetermined waypoints, avoid no-fly zones, and achieve the desired target conditions within allowable tolerances.

  2. Simulation of Trajectories for High Specific Impulse Deep Space Exploration

    NASA Technical Reports Server (NTRS)

    Polsgrove, Tara; Adams, Robert B.; Brady, Hugh J. (Technical Monitor)

    2002-01-01

    Difficulties in approximating flight times and deliverable masses for continuous thrust propulsion systems have complicated comparison and evaluation of proposed propulsion concepts. These continuous thrust propulsion systems are of interest to many groups, not the least of which are the electric propulsion and fusion communities. Several charts plotting the results of well-known trajectory simulation codes were developed and are contained in this paper. These charts illustrate the dependence of time of flight and payload ratio on jet power, initial mass, specific impulse and specific power. These charts are intended to be a tool by which people in the propulsion community can explore the possibilities of their propulsion system concepts. Trajectories were simulated using the tools VARITOP and IPOST. VARITOP is a well known trajectory optimization code that involves numerical integration based on calculus of variations. IPOST has several methods of trajectory simulation; the one used in this paper is Cowell's method for full integration of the equations of motion. The analytical method derived in the companion paper was also used to simulate the trajectory. The accuracy of this method is discussed in the paper.

  3. Trajectories in Operating a Handheld Tool

    ERIC Educational Resources Information Center

    Heuer, Herbert; Sulzenbruck, Sandra

    2009-01-01

    The authors studied the trajectories of the hand and of the tip of a handheld sliding first-order lever in aiming movements. With this kind of tool, straight trajectories of the hand are generally associated with curved trajectories of the tip of the lever and vice versa. Trajectories of the tip of the lever exhibited smaller deviations from…

  4. Occupational Exposure to Cobalt and Tungsten in the Swedish Hard Metal Industry: Air Concentrations of Particle Mass, Number, and Surface Area

    PubMed Central

    Bryngelsson, Ing-Liss; Pettersson, Carin; Husby, Bente; Arvidsson, Helena; Westberg, Håkan

    2016-01-01

    Exposure to cobalt in the hard metal industry entails severe adverse health effects, including lung cancer and hard metal fibrosis. The main aim of this study was to determine exposure air concentration levels of cobalt and tungsten for risk assessment and dose–response analysis in our medical investigations in a Swedish hard metal plant. We also present mass-based, particle surface area, and particle number air concentrations from stationary sampling and investigate the possibility of using these data as proxies for exposure measures in our study. Personal exposure full-shift measurements were performed for inhalable and total dust, cobalt, and tungsten, including personal real-time continuous monitoring of dust. Stationary measurements of inhalable and total dust, PM2.5, and PM10 was also performed and cobalt and tungsten levels were determined, as were air concentration of particle number and particle surface area of fine particles. The personal exposure levels of inhalable dust were consistently low (AM 0.15mg m−3, range <0.023–3.0mg m−3) and below the present Swedish occupational exposure limit (OEL) of 10mg m−3. The cobalt levels were low as well (AM 0.0030mg m−3, range 0.000028–0.056mg m−3) and only 6% of the samples exceeded the Swedish OEL of 0.02mg m−3. For continuous personal monitoring of dust exposure, the peaks ranged from 0.001 to 83mg m−3 by work task. Stationary measurements showed lower average levels both for inhalable and total dust and cobalt. The particle number concentration of fine particles (AM 3000 p·cm−3) showed the highest levels at the departments of powder production, pressing and storage, and for the particle surface area concentrations (AM 7.6 µm2·cm−3) similar results were found. Correlating cobalt mass-based exposure measurements to cobalt stationary mass-based, particle area, and particle number concentrations by rank and department showed significant correlations for all measures except for particle

  5. Desert Dust Air Mass Mapping in the Western Sahara, using Particle Properties Derived from Space-based Multi-angle Imaging

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Fiebig, Marcus; Schladitz, Alexander; von Hoyningen-Huene, Wolfgang

    2008-01-01

    Coincident observations made over the Moroccan desert during the SAhara Mineral dUst experiMent (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from Multi-angle Imaging SpectroRadiometer (MISR) observations, and to place the sub-orbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days for which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 to 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR's ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape, and single-scattering albedo. For the three study days, the satellite observations (a) highlight regional gradients in the mix of dust and background spherical particles, (b) identify a dust plume most likely part of a density flow, and (c) show an air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometers away.

  6. Photochemical trajectory modelling studies of the 1987 Antarctic spring vortex

    NASA Technical Reports Server (NTRS)

    Austin, J.; Jones, R. L.; Mckenna, D. S.

    1988-01-01

    Simulations of Antarctic ozone photochemistry performed using a photochemical model integrated along air parcel trajectories are described. This type of model has a major advantage at high latitudes of being able to simulate correctly the complex interaction between photolysis and temperature fields, which, because of the polar night cannot be represented accurately in a zonally averaged framework. Isentropic air parcel trajectories were computed using Meteorological Office global model analyses and forecast fields from positions along the ER-2 flight paths during the Airborne Antarctic Ozone Experiment in Austral Spring 1987. A photochemical model is integrated along these trajectories using the aircraft observations to initialize constituent concentrations. The model includes additional reactions of the ClO dimer and also bromine reactions, which are thought to play a significant role in Antarctica. The model also includes heterogeneous reactions which are invoked when the air parcel passes through a polar stratospheric cloud (PSC). The existence of a PSC is determined throughout the course of the model integration from the parcel temperature and the saturated vapour pressure of water over an assumed H2O/HNO3 mixture. The air parcel temperature is used to determine the saturated vapor pressure of HNO3 over the same mixture. Mixing ratios which exceed saturation result in condensation of the excess in the model and hence lead to a reduction of the amount of gas phase NO2 available for chemical reaction.

  7. Quantification of VX vapor in ambient air by liquid chromatography isotope dilution tandem mass spectrometric analysis of glass bead filled sampling tubes.

    PubMed

    Evans, Ronald A; Smith, Wendy L; Nguyen, Nam-Phuong; Crouse, Kathy L; Crouse, Charles L; Norman, Steven D; Jakubowski, E Michael

    2011-02-15

    An analysis method has been developed for determining low parts-per-quadrillion by volume (ppqv) concentrations of nerve agent VX vapor actively sampled from ambient air. The method utilizes glass bead filled depot area air monitoring system (DAAMS) sampling tubes with isopropyl alcohol extraction and isotope dilution using liquid chromatography coupled with a triple-quadrupole mass spectrometer (LC/MS/MS) with positive ion electrospray ionization for quantitation. The dynamic range was from one-tenth of the worker population limit (WPL) to the short-term exposure limit (STEL) for a 24 L air sample taken over a 1 h period. The precision and accuracy of the method were evaluated using liquid-spiked tubes, and the collection characteristics of the DAAMS tubes were assessed by collecting trace level vapor generated in a 1000 L continuous flow chamber. The method described here has significant improvements over currently employed thermal desorption techniques that utilize a silver fluoride pad during sampling to convert VX to a higher volatility G-analogue for gas chromatographic analysis. The benefits of this method are the ability to directly analyze VX with improved selectivity and sensitivity, the injection of a fraction of the extract, quantitation using an isotopically labeled internal standard, and a short instrument cycle time.

  8. The application of time-dependent ice crystal trajectory and growth model for the evaluation of cloud seeding experiment using liquid carbon dioxide

    NASA Astrophysics Data System (ADS)

    Nishiyama, K.; Wakimizu, K.; Maki, T.; Suzuki, Y.; Morita, O.; Tomine, K.

    2012-12-01

    This study evaluated the results of cloud seeding experiment conducted on 17th January, 2008, in western Kyushu, Japan, using simplified time-dependent ice crystal growth and trajectory cloud model, which is characterized by 1) depositional diffusion growth process only of an ice crystal, and 2) the pursuit of the growing ice crystal based on wind field and ice crystal terminal velocity. For the estimation of the ice crystal growth and trajectory, the model specifies ice supersaturation ratio that expresses the degree of competition growth among ice crystals formed by LC seeding for existing water vapor, assuming no effect of natural ice crystals. The model is based on ice crystal growth along a- and c-axes depending on air temperature and ice supersatuation, according to Chen and Lamb (1994). The cloud seeding experiment was conducted by applying homogeneous nucleation (rapid cooling of air mass and subsequent formation of many ice crystals~1013/g LC) of Liquid Carbon (LC) dioxide seeding under typical winter-type snowfall-inducing weather situation characterized by the outbreak of cold air masses from the Siberia. The result of aircraft horizontally-penetrating seeding of LC into lower layer (-2 degree C) of supercooled convective cloud with 1km thickness above the freezing level led to the formation of an artificially-induced 'isolated' radar echo (the left figures of Fig. 1) in dominant 'no-natural radar echo region'. In other words, natural biases were eliminated by the formation of the isolated radar echo. This fact provides the shortcut for evaluating the result of cloud seeding experiment. In the next, the observed cloud seeding results were evaluated by estimating the trajectory of artificially-induced growing ice crystal. The results show that the trajectory of artificial ice crystals depends on the degree of completion growth mode. Free growth brings rapid growth of an ice crystal and, therefore, the ice crystal falls into lower layers for a short time

  9. Student Understanding of the Volume, Mass, and Pressure of Air within a Sealed Syringe in Different States of Compression.

    ERIC Educational Resources Information Center

    de Berg, Kevin Charles

    1995-01-01

    Investigation of (n=101) 17- to 18-year-old students' responses to a task relating to Boyle's Law for gases found that 34% to 38% of students did not understand the concepts of volume and mass, respectively, of a gas under the given circumstances. (Author/MKR)

  10. Locomotor Trajectories of Stroke Patients during Oriented Gait and Turning

    PubMed Central

    Van Hamme, Angele; Bensmail, Djamel

    2016-01-01

    Background The Timed Up and Go (TUG) test is widely used to assess locomotion in patients with stroke and is considered to predict the risk of falls. The analysis of locomotor trajectories during the TUG appears pertinent in stroke patients. The aims of this study were i) to analyze locomotor trajectories in patients with stroke during the walking and turning sub-tasks of the TUG, and to compare them with healthy subjects, ii) to determine whether trajectory parameters provide additional information to that provided by the conventional measure (performance time), iii) to compare the trajectory parameters of fallers and non-fallers with stroke and of patients with right and left hemisphere stroke, and iv) to evaluate correlations between trajectory parameters and Berg Balance Scale scores. Methods 29 patients with stroke (mean age 54.2±12.2 years, 18 men, 8 fallers) and 25 healthy subjects (mean age 51.6±8.7 years, 11 men) underwent three-dimensional analysis of the TUG. The trajectory of the center of mass was analyzed by calculation of the global trajectory length, Hausdorff distance and Dynamic Time Warping. The parameters were compared with a reference trajectory during the total task and each sub-task (Go, Turn, Return) of the TUG. Results Values of trajectory parameters were significantly higher for the stroke group during the total TUG and the Go and Turn sub-tasks (p<0.05). Moreover, logistic regression indicated that these parameters better discriminated stroke patients and healthy subjects than the conventional timed performance during the Go sub-task. In addition, fallers were distinguished by higher Dynamic Time Warping during the Go (p<0.05). There were no differences between patients with right and left hemisphere stroke. Discussion and Conclusion The trajectories of the stroke patients were longer and more deviated during the turn and the preceding phase. Trajectory parameters provided additional information to timed performance of this locomotor

  11. In-Line Ozonation for Sensitive Air-Monitoring of a Mustard-Gas Simulant by Atmospheric Pressure Chemical Ionization Mass Spectrometry.

    PubMed

    Okumura, Akihiko

    2015-09-01

    A highly sensitive method for real-time air-monitoring of mustard gas (bis(2-chloroethyl) sulfide, HD), which is a lethal blister agent, is proposed. Humidified air containing a HD simulant, 2-chloroethyl ethyl sulfide (2CEES), was mixed with ozone and then analyzed by using an atmospheric pressure chemical ionization ion trap tandem mass spectrometer. Mass-spectral ion peaks attributable to protonated molecules of intact, monooxygenated, and dioxygenated 2CEES (MH(+), MOH(+), and MO(2)H(+), respectively) were observed. As ozone concentration was increased from zero to 30 ppm, the signal intensity of MH(+) sharply decreased, that of MOH(+) increased once and then decreased, and that of MO(2)H(+) sharply increased until reaching a plateau. The signal intensity of MO(2)H(+) at the plateau was 40 times higher than that of MH(+) and 100 times higher than that of MOH(+) in the case without in-line ozonation. Twenty-ppm ozone gas was adequate to give a linear calibration curve for 2CEES obtained by detecting the MO(2)H(+) signal in the concentration range up to 60 μg/m(3), which is high enough for hygiene management. In the low concentration range lower than 3 μg/m(3), which is equal to the short-term exposure limit for HD, calibration plots unexpectedly fell off the linear calibration curve, but 0.6-μg/m(3) vapor was actually detected with the signal-to-noise ratio of nine. Ozone was generated from instrumentation air by using a simple and inexpensive home-made generator. 2CEES was ozonated in 1-m extended sampling tube in only 1 s.

  12. In-Line Ozonation for Sensitive Air-Monitoring of a Mustard-Gas Simulant by Atmospheric Pressure Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Okumura, Akihiko

    2015-09-01

    A highly sensitive method for real-time air-monitoring of mustard gas (bis(2-chloroethyl) sulfide, HD), which is a lethal blister agent, is proposed. Humidified air containing a HD simulant, 2-chloroethyl ethyl sulfide (2CEES), was mixed with ozone and then analyzed by using an atmospheric pressure chemical ionization ion trap tandem mass spectrometer. Mass-spectral ion peaks attributable to protonated molecules of intact, monooxygenated, and dioxygenated 2CEES (MH+, MOH+, and MO2H+, respectively) were observed. As ozone concentration was increased from zero to 30 ppm, the signal intensity of MH+ sharply decreased, that of MOH+ increased once and then decreased, and that of MO2H+ sharply increased until reaching a plateau. The signal intensity of MO2H+ at the plateau was 40 times higher than that of MH+ and 100 times higher than that of MOH+ in the case without in-line ozonation. Twenty-ppm ozone gas was adequate to give a linear calibration curve for 2CEES obtained by detecting the MO2H+ signal in the concentration range up to 60 μg/m3, which is high enough for hygiene management. In the low concentration range lower than 3 μg/m3, which is equal to the short-term exposure limit for HD, calibration plots unexpectedly fell off the linear calibration curve, but 0.6-μg/m3 vapor was actually detected with the signal-to-noise ratio of nine. Ozone was generated from instrumentation air by using a simple and inexpensive home-made generator. 2CEES was ozonated in 1-m extended sampling tube in only 1 s.

  13. Climatological classification of five sectors in the Iberian Peninsula using columnar (AOD, α) and surface (PM10, PM2.5) aerosol data supported by air mass apportioning

    NASA Astrophysics Data System (ADS)

    Cachorro, Victoria; Mateos, David; Toledano, Carlos; Burgos, Maria A.; Bennouna, Yasmine; Torres, Benjamín; Fuertes, David; González, Ramiro; Guirado, Carmen; Román, Roberto; Velasco-Merino, Cristian; Marcos, Alberto; Calle, Abel; de Frutos, Angel M.

    2015-04-01

    The study of atmospheric aerosol over the Iberian Peninsula (IP) under a climatologic perspective is an interesting and meaningful aim due to the wide variety of conditions (geographical position, air masses, topography, among others) which cause a complex role of the distribution of aerosol properties. In the deeply investigation on the annual cycle and time evolution of the particulate matter lower than 10 µm (PM10, surface) and aerosol optical depth (AOD, columnar) in a large number of sites covering the period 2000-2013, five sectors can be distinguished in the IP. Both set of data belong to EMEP and AERONET networks respectively, as representative of aerosol air quality and climate studies, are complementary elements for a global aerosol research. The prevalence of fine-coarse particles is also analyzed over each sector. Seasonal bimodality of the PM10 annual cycle with a strong North-South gradient is observed in most sites, but this is only reported in the AOD climatology for the southern IP. The northern coast is clearly governed by the Atlantic Ocean influence, while the northeastern area is modulated by the Mediterranean Sea. The southern area, very close to the African continent, presents a large influence of desert dust intrusions. However, the southern Atlantic and Mediterranean coast present discrepancies and two sectors have been defined in this area. Finally, the center of the Peninsula is a mix of conditions, with north-south and east-west gradients of different magnitude. Overall, there is a relationship between PM10 and AOD with a proportional factor varying from 20 to 90, depending on the sector. The particular characteristic of PM10-AOD annual cycle of each geographical sector can be understood by the different climatology of the air mass origins observed at 500 and 1500 m (a.s.l.) and its apportioning to PM10 and AOD, respectively.

  14. ExoMars alternative escape trajectories with Soyuz/Fregat.

    PubMed

    Gil-Fernández, Jesús; Van Damme, Carlos Corral; Graziano, Mariella; Amata, G B; Cogo, F; Perino, M A

    2005-12-01

    The objectives of ExoMars are to inject an orbiter around Mars and to land a rover on the surface to look for possible traces of life. During the first stages of the feasibility analysis, the mass margin of the orbiter was very small for a direct transfer in the Soyuz/Fregat scenario. An analysis of the combined use of lunar swing-bys and the Sun gravity gradient is performed with WESBOT in order to obtain alternative trajectories for injecting higher mass into Mars transfer. WESBOT is a GMV tool to find WSB transfers to the Moon and to design escape trajectories by performing several swing-bys with the Moon and the Earth. The weak stability boundary has been successfully used for lunar transfers (Hiten, SMART-1). For escape trajectories from the Earth, the potential mass gains depend on the escape direction and the departure date to make a series of gravity assists with the help of the Sun gravity gradient to save DeltaV. Several strategies are studied depending on the number and order of swing-bys. The departing conditions (date and orbit) are optimized but the arrival date to Mars is maintained because of mission requirements. For each type of strategy, a systematic search of initial guess trajectories is performed. The initial guess trajectory is made up of patched conics arcs and multiple shooting arcs when necessary. The optimal trajectories for the various scenarios are presented and show different morphologies. An analysis in terms of applicability to the ExoMars mission is included.

  15. Lidar observations of ozone changes induced by subpolar air mass motion over Table Mountain, California (34.4 deg N)

    NASA Technical Reports Server (NTRS)

    Mcgee, Thomas J.; Newman, Paul; Ferrare, Richard; Whiteman, David; Burris, John; Butler, James; Godin, Sophie; Mcdermid, I. Stuart

    1990-01-01

    Between October 15 and November 8, 1988, the Goddard Space Flight Center mobile stratospheric lidar was in place at the (JPL) Table Mountain Facility (located at 34.4 deg N, 117.7 deg W) for the purpose of intercomparing with the JPL lidar permanently stationed at the observatory. During the course of the intercomparison both lidar systems detected a significant change in the vertical profile of ozone lasting for several days. An analysis of meteorological data available from the National Meteorological Center has shown this change to be dynamical in origin due to the transport of subpolar air over Table Mountain.

  16. Experimental Evaluation of an Integrated Datalink and Automation-Based Strategic Trajectory Concept

    NASA Technical Reports Server (NTRS)

    Mueller, Eric

    2007-01-01

    This paper presents research on the interoperability of trajectory-based automation concepts and technologies with modern Flight Management Systems and datalink communication available on many of today s commercial aircraft. A tight integration of trajectory-based ground automation systems with the aircraft Flight Management System through datalink will enable mid-term and far-term benefits from trajectory-based automation methods. A two-way datalink connection between the trajectory-based automation resident in the Center/TRACON Automation System and the Future Air Navigation System-1 integrated FMS/datalink in NASA Ames B747-400 Level D simulator has been established and extensive simulation of the use of datalink messages to generate strategic trajectories completed. A strategic trajectory is defined as an aircraft deviation needed to solve a conflict or honor a route request and then merge the aircraft back to its nominal preferred trajectory using a single continuous trajectory clearance. Engineers on the ground side of the datalink generated lateral and vertical trajectory clearances and transmitted them to the Flight Management System of the 747; the airborne automation then flew the new trajectory without human intervention, requiring the flight crew only to review and to accept the trajectory. This simulation established the protocols needed for a significant majority of the trajectory change types required to solve a traffic conflict or deviate around weather. This demonstration provides a basis for understanding the requirements for integration of trajectory-based automation with current Flight Management Systems and datalink to support future National Airspace System operations.

  17. CFD Analysis of Swing of Cricket Ball and Trajectory Prediction

    NASA Astrophysics Data System (ADS)

    G, Jithin; Tom, Josin; Ruishikesh, Kamat; Jose, Jyothish; Kumar, Sanjay

    2013-11-01

    This work aims to understand the aerodynamics associated with the flight and swing of a cricket ball and predict its flight trajectory over the course of the game: at start (smooth ball) and as the game progresses (rough ball). Asymmetric airflow over the ball due to seam orientation and surface roughness can cause flight deviation (swing). The values of Drag, Lift and Side forces which are crucial for determining the trajectory of the ball were found with the help of FLUENT using the standard K- ɛ model. Analysis was done to study how the ball velocity, spin imparted to be ball and the tilt of the seam affects the movement of the ball through air. The governing force balance equations in 3 dimensions in combination a MATLAB code which used Heun's method was used for obtaining the trajectory of the ball. The conditions for the conventional swing and reverse swing to occur were deduced from the analysis and found to be in alignment with the real life situation. Critical seam angle for maximum swing and transition speed for normal to reverse swing were found out. The obtained trajectories were compared to real life hawk eye trajectories for validation. The analysis results were in good agreement with the real life situation.

  18. Associations between Prenatal traffic-related air pollution exposure and birth weight: Modification by sex and maternal pre-pregnancy body mass index

    PubMed Central

    Coull, Brent A.; Just, Allan C.; Maxwell, Sarah L.; Schwartz, Joel; Gryparis, Alexandros; Kloog, Itai; Wright, Rosalind J.; Wright, Robert O.

    2015-01-01

    Background Prenatal traffic-related air pollution exposure is linked to adverse birth outcomes. However, modifying effects of maternal body mass index (BMI) and infant sex remain virtually unexplored. Objectives We examined whether associations between prenatal air pollution and birth weight differed by sex and maternal BMI in 670 urban ethnically mixed mother-child pairs. Methods Black carbon (BC) levels were estimated using a validated spatio-temporal land-use regression (LUR) model; fine particulate matter (PM2.5) was estimated using a hybrid LUR model incorporating satellite-derived Aerosol Optical Depth measures. Using stratified multivariable-adjusted regression analyses, we examined whether associations between prenatal air pollution and calculated birth weight for gestational age (BWGA) z-scores varied by sex and maternal pre-pregnancy BMI. Results Median birth weight was 3.3±0.6 kg; 33% of mothers were obese (BMI ≥30 kg/m3). In stratified analyses, the association between higher PM2.5 and lower birth weight was significant in males of obese mothers (−0.42 unit of BWGA z-score change per IQR increase in PM2.5, 95%CI: −0.79 to −0.06) ( PM2.5 × sex × obesity Pinteraction=0.02). Results were similar for BC models (Pinteraction=0.002). Conclusions Associations of prenatal exposure to traffic-related air pollution and reduced birth weight were most evident in males born to obese mothers. PMID:25601728

  19. Quantum trajectories of superconducting qubits

    NASA Astrophysics Data System (ADS)

    Weber, Steven J.; Murch, Kater W.; Kimchi-Schwartz, Mollie E.; Roch, Nicolas; Siddiqi, Irfan

    2016-08-01

    In this review, we discuss recent experiments that investigate how the quantum sate of a superconducting qubit evolves during measurement. We provide a pedagogical overview of the measurement process, when the qubit is dispersively coupled to a microwave frequency cavity, and the qubit state is encoded in the phase of a microwave tone that probes the cavity. A continuous measurement record is used to reconstruct the individual quantum trajectories of the qubit state, and quantum state tomography is performed to verify that the state has been tracked accurately. Furthermore, we discuss ensembles of trajectories, time-symmetric evolution, two-qubit trajectories, and potential applications in measurement-based quantum error correction. xml:lang="fr"

  20. Optimal trajectories for efficient atomic transport without final excitation

    SciTech Connect

    Chen Xi; Torrontegui, E.; Muga, J. G.; Stefanatos, Dionisis; Li, Jr-Shin

    2011-10-15

    We design optimal harmonic-trap trajectories to transport cold atoms without final excitation, combining an inverse engineering technique based on Lewis-Riesenfeld invariants with optimal control theory. Since actual traps are not really harmonic, we keep the relative displacement between the center of mass of the transport modes and the trap center bounded. Under this constraint, optimal protocols are found according to different physical criteria. The minimum time solution has a ''bang-bang'' form, and the minimum displacement solution is of ''bang-off-bang'' form. The optimal trajectories for minimizing the transient energy are also discussed.

  1. Mass of chlorinated volatile organic compounds removed by Pump-and-Treat, Naval Air Warfare Center, West Trenton, New Jersey, 1996-2010

    USGS Publications Warehouse

    Lacombe, Pierre J.

    2011-01-01

    Pump and Treat (P&T) remediation is the primary technique used to contain and remove trichloroethylene (TCE) and its degradation products cis 1-2,dichloroethylene (cDCE) and vinyl chloride (VC) from groundwater at the Naval Air Warfare Center (NAWC), West Trenton, NJ. Three methods were used to determine the masses of TCE, cDCE, and VC removed from groundwater by the P&T system since it became fully operational in 1996. Method 1, is based on the flow volume and concentrations of TCE, cDCE, and VC in groundwater that entered the P&T building as influent. Method 2 is based on withdrawal volume from each active recovery well and the concentrations of TCE, cDCE, and VC in the water samples from each well. Method 3 compares the maximum monthly amount of TCE, cDCE, and VC from Method 1 and Method 2. The greater of the two values is selected to represent the masses of TCE, cDCE and VC removed from groundwater each month. Previously published P&T monthly reports used Method 1 to determine the mass of TCE, cDCE, and VC removed. The reports state that 8,666 pounds (lbs) of TCE, 13,689 lbs of cDCE, and 2,455 lbs of VC were removed by the P&T system during 1996-2010. By using Method 2, the mass removed was determined to be 8,985 lbs of TCE, 17,801 lbs of cDCE, and 3,056 lbs of VC removed, and Method 3, resulted in 10,602 lbs of TCE, 21,029 lbs of cDCE, and 3,496 lbs of VC removed. To determine the mass of original TCE removed from groundwater, the individual masses of TCE, cDCE, and VC (determined using Methods 1, 2, and 3) were converted to numbers of moles, summed, and converted to pounds of original TCE. By using the molar conversion the mass of original TCE removed from groundwater by Methods 1, 2, and 3 was 32,381 lbs, 39,535 lbs, and 46,452 lbs, respectively, during 1996-2010. P&T monthly reports state that 24,805 lbs of summed TCE, cDCE, and VC were removed from groundwater. The simple summing method underestimates the mass of original TCE removed by the P&T system.

  2. Dynamic behavior of air lubricated pivoted-pad journal-bearing, rotor system. 2: Pivot consideration and pad mass

    NASA Technical Reports Server (NTRS)

    Nemeth, Z. N.

    1972-01-01

    Rotor bearing dynamic tests were conducted with tilting-pad journal bearings having three different pad masses and two different pivot geometries. The rotor was vertically mounted and supported by two three-pad tilting-pad gas journal bearings and a simple externally pressurized thrust bearing. The bearing pads were 5.1 cm (2.02 in.) in diameter and 2.8 cm (1.5 in.) long. The length to diameter ratio was 0.75. One pad was mounted on a flexible diaphragm. The bearing supply pressure ranged from 0 to 690 kilonewtons per square meter (0 to 100 psig), and speeds ranged to 38,500 rpm. Heavy mass pad tilting-pad assemblies produced three rotor-bearing resonances above the first two rotor critical speeds. Lower supply pressure eliminated the resonances. The resonances were oriented primarily in the direction normal to the diaphragm.

  3. Assessment of the Losses Due to Self Absorption by Mass Loading on Radioactive Particulate Air Stack Sample Filters

    SciTech Connect

    Smith, Brian M.; Barnett, J. Matthew; Ballinger, Marcel Y.

    2011-01-18

    This report discusses the effect of mass loading of a membrane filter on the self absorption of radioactive particles. A relationship between mass loading and percent loss of activity is presented. Sample filters were collected from Pacific Northwest National Laboratory (PNNL) facilities in order to analyze the current self absorption correction factor of 0.85 that is being used for both alpha and beta particles. Over an eighteen month period from February 2009 to July 2010, 116 samples were collected and analyzed from eight different building stacks in an effort coordinated by the Effluent Management group. Eleven unused filters were also randomly chosen to be analyzed in order to determine background radiation. All of these samples were collected and analyzed in order to evaluate the current correction factor being used.

  4. Cost trajectories for cancer patients

    PubMed Central

    Wodchis, W.P.; Arthurs, E.; Khan, A.I.; Gandhi, S.; MacKinnon, M.; Sussman, J.

    2016-01-01

    Background Health care spending is known to be highly skewed, with a small subset of the population consuming a disproportionate amount of health care resources. Patients with cancer are high-cost users because of high incremental health care costs for treatment and the growing prevalence of cancer. The objectives of the present study included characterizing cancer-patient trajectories by cost, and identifying the patient and health system characteristics associated with high health system costs after cancer treatment. Methods This retrospective cohort study identified Ontario adults newly diagnosed with cancer between 1 April 2009 and 30 September 2010. Costs of health care use before, during, and after cancer episodes were used to develop trajectories of care. Descriptive analyses examined differences between the trajectories in terms of clinical and health system characteristics, and a logistic regression approach identified predictors of being a high-cost user after a cancer episode. Results Ten trajectories were developed based on whether patients were high- or low-cost users before and after their cancer episode. The most common trajectory represented patients who were low-cost in the year before cancer, survived treatment, and continued to be low-cost in the year after cancer (31.4%); stage ii cancer of the male genital system was the most common diagnosis within that trajectory. Regression analyses identified increases in age and in multimorbidity and low continuity of care as the strongest predictors of high-cost status after cancer. Conclusions Findings highlight an opportunity to proactively identify patients who might transition to high-cost status after cancer treatment and to remediate that transition. PMID:26985150

  5. Transport of Antarctic stratospheric strongly dehydrated air into the troposphere observed during the HALO-ESMVal campaign 2012

    NASA Astrophysics Data System (ADS)

    Rolf, C.; Afchine, A.; Bozem, H.; Buchholz, B.; Ebert, V.; Guggenmoser, T.; Hoor, P.; Konopka, P.; Kretschmer, E.; Müller, S.; Schlager, H.; Spelten, N.; Sumińska-Ebersoldt, O.; Ungermann, J.; Zahn, A.; Krämer, M.

    2015-08-01

    Dehydration in the Antarctic winter stratosphere is a well-known phenomenon that is annually observed by satellites and occasionally observed by balloon-borne measurements. However, in situ measurements of dehydrated air masses in the Antarctic vortex are very rare. Here, we present detailed observations with the in situ and GLORIA remote sensing instrument payload aboard the German aircraft HALO. Strongly dehydrated air masses down to 1.6 ppmv of water vapor were observed as far north as 47° S in an altitude between 12 and 13 km in the lowermost stratosphere. The dehydration can be traced back to individual ice formation events above the Antarctic Peninsula and Plateau, where ice crystals sedimented out and water vapor was irreversibly removed. Within these dehydrated stratospheric air masses, filaments of moister air reaching down to the tropopause are detected with the high-resolution limb sounder, GLORIA. Furthermore, dehydrated air masses are observed with GLORIA in the Antarctic lowermost stratosphere down to 7 km. With the help of a backward trajectory analysis, a midlatitude origin of the moist filaments in the vortex can be identified, while the dry air masses down to 7 km have stratospheric origins. Antarctic stratosphere-troposphere exchange (STE) and transport of dehydrated air masses into the troposphere are investigated. Further, it is shown that the exchange process can be attributed to several successive Rossby wave events in combination with an isentropic exchange of air masses across the thermal tropopause. The transport into the troposphere is caused by air masses that are detached from the potential vorticity (PV) structure by Rossby wave breaking events and subsequently transported diabatically across the dynamical tropopause. Once transported to the troposphere, air masses with stratospheric origin can reach near-surface levels within several days.

  6. Ballute Aerocapture Trajectories at Neptune

    NASA Technical Reports Server (NTRS)

    Lyons, Daniel T.; Johnson, Wyatt

    2004-01-01

    Using an inflatable ballute system for aerocapture at planets and moons with atmospheres has the potential to provide significant performance benefits compared not only to traditional all propulsive capture, but also to aeroshell based aerocapture technologies. This paper discusses the characteristics of entry trajectories for ballute aerocapture at Neptune. These trajectories are the first steps in a larger systems analysis effort that is underway to characterize and optimize the performance of a ballute aerocapture system for future missions not only at Neptune, but also the other bodies with atmospheres.

  7. Complexity Management Using Metrics for Trajectory Flexibility Preservation and Constraint Minimization

    NASA Technical Reports Server (NTRS)

    Idris, Husni; Shen, Ni; Wing, David J.

    2011-01-01

    The growing demand for air travel is increasing the need for mitigating air traffic congestion and complexity problems, which are already at high levels. At the same time new surveillance, navigation, and communication technologies are enabling major transformations in the air traffic management system, including net-based information sharing and collaboration, performance-based access to airspace resources, and trajectory-based rather than clearance-based operations. The new system will feature different schemes for allocating tasks and responsibilities between the ground and airborne agents and between the human and automation, with potential capacity and cost benefits. Therefore, complexity management requires new metrics and methods that can support these new schemes. This paper presents metrics and methods for preserving trajectory flexibility that have been proposed to support a trajectory-based approach for complexity management by airborne or ground-based systems. It presents extensions to these metrics as well as to the initial research conducted to investigate the hypothesis that using these metrics to guide user and service provider actions will naturally mitigate traffic complexity. The analysis showed promising results in that: (1) Trajectory flexibility preservation mitigated traffic complexity as indicated by inducing self-organization in the traffic patterns and lowering traffic complexity indicators such as dynamic density and traffic entropy. (2)Trajectory flexibility preservation reduced the potential for secondary conflicts in separation assurance. (3) Trajectory flexibility metrics showed potential application to support user and service provider negotiations for minimizing the constraints imposed on trajectories without jeopardizing their objectives.

  8. Gestational weight gain trajectories in primary care

    PubMed Central

    Piccinini-Vallis, Helena; Lee-Baggley, Dayna; Stewart, Moira; Ryan, Bridget

    2016-01-01

    Objective To identify gestational weight gain trajectories, stratified by prepregnancy body mass index (BMI), of women with singleton pregnancies who received prenatal care in a primary care setting, and to compare these trajectories with the 2009 Institute of Medicine gestational weight gain recommendations. Design Retrospective cohort study. Setting Halifax, NS. Participants Women who received prenatal care at the Dalhousie Family Medicine clinics in Halifax from 2009 to 2013. Main outcome measures For each prenatal visit, gestational age and weight measurements were obtained. Multilevel modeling was used to analyze the gestational weight gain trajectories. The upper limit of the guideline-recommended weekly gestational weight gain was compared with the 95% CI of the observed mean weekly gestational weight gain for each prepregnancy BMI category. Results A total of 280 women were included in the analyses. There was a significant interaction between prepregnancy BMI category and gestational weight gain over time (P < .001), with gestational weight gain being significantly lower among women with prepregnancy BMI of 30.0 kg/m2 or greater compared with those with BMI of 18.5 to less than 25.0 kg/m2 and 25.0 to less than 30.0 kg/m2. When comparing women’s weight gain with the recommendations, women with prepregnancy BMI of 25.0 to less than 30.0 kg/m2 had the most guideline discordance, deviating from the weight gain recommendations at 20 weeks’ gestation. Conclusion These results are relevant and of benefit to women and clinicians wishing to address excess gestational weight gain, and to researchers and policy makers developing interventions aimed at curbing gestational weight gain in primary care. Although our results showed women with prepregnancy BMI of 25.0 to less than 30.0 kg/m2 gained the most excess, guideline-discordant weight, interventions should target all women planning or experiencing a pregnancy.

  9. Two-dimensional two-phase mass transport model for methanol and water crossover in air-breathing direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Ye, Dingding; Zhu, Xun; Liao, Qiang; Li, Jun; Fu, Qian

    A two-dimensional two-phase mass transport model has been developed to predict methanol and water crossover in a semi-passive direct methanol fuel cell with an air-breathing cathode. The mass transport in the catalyst layer and the discontinuity in liquid saturation at the interface between the diffusion layer and catalyst layer are particularly considered. The modeling results agree well with the experimental data of a home-assembled cell. Further studies on the typical two-phase flow and mass transport distributions including species, pressure and liquid saturation in the membrane electrode assembly are investigated. Finally, the methanol crossover flux, the net water transport coefficient, the water crossover flux, and the total water flux at the cathode as well as their contributors are predicted with the present model. The numerical results indicate that diffusion predominates the methanol crossover at low current densities, while electro-osmosis is the dominator at high current densities. The total water flux at the cathode is originated primarily from the water generated by the oxidation reaction of the permeated methanol at low current densities, while the water crossover flux is the main source of the total water flux at high current densities.

  10. Direct AFM force measurements between air bubbles in aqueous polydisperse sodium poly(styrene sulfonate) solutions: effect of collision speed, polyelectrolyte concentration and molar mass.

    PubMed

    Browne, Christine; Tabor, Rico F; Grieser, Franz; Dagastine, Raymond R

    2015-07-01

    Interactions between colliding air bubbles in aqueous solutions of polydisperse sodium poly(styrene sulfonate) (NaPSS) using direct force measurements were studied. The forces measured with deformable interfaces were shown to be more sensitive to the presence of the polyelectrolytes when compared to similar measurements using rigid interfaces. The experimental factors that were examined were NaPSS concentration, bubble collision velocity and polyelectrolyte molar mass. These measurements were then compared with an analytical model based on polyelectrolyte scaling theory in order to explain the effects of concentration and bubble deformation on the interaction between bubbles. Typically structural forces from the presence of monodisperse polyelectrolyte between interacting surfaces may be expected, however, it was found that the polydispersity in molar mass resulted in the structural forces to be smoothed and only a depletion interaction was able to be measured between interacting bubbles. It was found that an increase in number density of NaPSS molecules resulted in an increase in the magnitude of the depletion interaction. Conversely this interaction was overwhelmed by an increase in the fluid flow in the system at higher bubble collision velocities. Polymer molar mass dispersity plays a significant role in the interactions present between the bubbles and has implications that also affect the polyelectrolyte overlap concentration of the solution. Further understanding of these implications can be expected to play a role in the improvement in operations in such fields as water treatment and mineral processing where polyelectrolytes are used extensively.

  11. Determining air pollutant emission rates based on mass balance using airborne measurement data over the Alberta oil sands operations

    NASA Astrophysics Data System (ADS)

    Gordon, M.; Li, S.-M.; Staebler, R.; Darlington, A.; Hayden, K.; O'Brien, J.; Wolde, M.

    2015-09-01

    Top-down approaches to measure total integrated emissions provide verification of bottom-up, temporally resolved, inventory-based estimations. Aircraft-based measurements of air pollutants from sources in the Canadian oil sands were made in support of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring during a summer intensive field campaign between 13 August and 7 September 2013. The measurements contribute to knowledge needed in support of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring. This paper describes the top-down emission rate retrieval algorithm (TERRA) to determine facility emissions of pollutants, using SO2 and CH4 as examples, based on the aircraft measurements. In this algorithm, the flight path around a facility at multiple heights is mapped to a two-dimensional vertical screen surrounding the facility. The total transport of SO2 and CH4 through this screen is calculated using aircraft wind measurements, and facility emissions are then calculated based on the divergence theorem with estimations of box-top losses, horizontal and vertical turbulent fluxes, surface deposition, and apparent losses due to air densification and chemical reaction. Example calculations for two separate flights are presented. During an upset condition of SO2 emissions on one day, these calculations are within 5 % of the industry-reported, bottom-up measurements. During a return to normal operating conditions, the SO2 emissions are within 11 % of industry-reported, bottom-up measurements. CH4 emissions calculated with the algorithm are relatively constant within the range of uncertainties. Uncertainty of the emission rates is estimated as less than 30 %, which is primarily due to the unknown SO2 and CH4 mixing ratios near the surface below the lowest flight level.

  12. Multi-Objective Trajectory Optimization of a Hypersonic Reconnaissance Vehicle with Temperature Constraints

    NASA Astrophysics Data System (ADS)

    Masternak, Tadeusz J.

    This research determines temperature-constrained optimal trajectories for a scramjet-based hypersonic reconnaissance vehicle by developing an optimal control formulation and solving it using a variable order Gauss-Radau quadrature collocation method with a Non-Linear Programming (NLP) solver. The vehicle is assumed to be an air-breathing reconnaissance aircraft that has specified takeoff/landing locations, airborne refueling constraints, specified no-fly zones, and specified targets for sensor data collections. A three degree of freedom scramjet aircraft model is adapted from previous work and includes flight dynamics, aerodynamics, and thermal constraints. Vehicle control is accomplished by controlling angle of attack, roll angle, and propellant mass flow rate. This model is incorporated into an optimal control formulation that includes constraints on both the vehicle and mission parameters, such as avoidance of no-fly zones and coverage of high-value targets. To solve the optimal control formulation, a MATLAB-based package called General Pseudospectral Optimal Control Software (GPOPS-II) is used, which transcribes continuous time optimal control problems into an NLP problem. In addition, since a mission profile can have varying vehicle dynamics and en-route imposed constraints, the optimal control problem formulation can be broken up into several "phases" with differing dynamics and/or varying initial/final constraints. Optimal trajectories are developed using several different performance costs in the optimal control formulation: minimum time, minimum time with control penalties, and maximum range. The resulting analysis demonstrates that optimal trajectories that meet specified mission parameters and constraints can be quickly determined and used for larger-scale operational and campaign planning and execution.

  13. Flapping Wing Micro Air Vehicles: An Analysis of the Importance of the Mass of the Wings to Flight Dynamics, Stability, and Control

    NASA Astrophysics Data System (ADS)

    Orlowski, Christopher T.

    The flight dynamics, stability, and control of a model flapping wing micro air vehicle are analyzed with a focus on the inertial and mass effects of the wings on the position and Orientation of the body. A multi-body, flight dynamics model is derived from first principles. The multi-body model predicts significant differences in the position and orientation of the flapping wing micro air vehicle, when compared to a flight dynamics model based on the standard aircraft, or six degree of freedom, equations of motion. The strongly coupled, multi-body equations of motion are transformed into first order form using an approximate inverse and appropriate assumptions. Local (naive) averaging of the first order system does not produce an accurate result and a new approximation technique named 'quarter-cycle' averaging is proposed. The technique is effective in reducing the error by at least an order of magnitude for three reference flight conditions. A stability analysis of the local averaged equations of motions, in the vicinity of a hover condition, produces a modal structure consist with the most common vertical takeoff or landing structure and independent stability analyses of the linearized flight dynamics of insect models. The inclusion of the wing effects produces a non-negligible change in the linear stability of a hawkmoth-sized model. The hovering solution is shown, under proper control, to produce a limit cycle. The control input to achieve a limit cycle is different if the flight dynamics model includes the wing effects or does not include the wing effects. Improper control input application will not produce the desired limit cycle effects. A scaling analysis is used to analyze the relative importance of the mass of the wings, based on the quarter-cycle approximation. The conclusion of the scaling analysis is that the linear momentum effects of the wings are always important in terms of the inertial position of the flapping wing micro air vehicle. Above a

  14. Application of high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for determination of chromium compounds in the air at the workplace.

    PubMed

    Stanislawska, Magdalena; Janasik, Beata; Wasowicz, Wojciech

    2013-12-15

    The toxicity and bioavailability of chromium species are highly dependable on the form or species, therefore determination of total chromium is insufficient for a complete toxicological evaluation and risk assessment. An analytical method for determination of soluble and insoluble Cr (III) and Cr (VI) compounds in welding fume at workplace air has been developed. The total chromium (Cr) was determined by using quadruple inductively coupled plasma mass spectrometry (ICP-MS) equipped with a dynamic reaction cell (DRC(®)). Soluble trivalent and hexavalent chromium compounds were determined by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A high-speed, reversed-phase CR C8 column (PerkinElmer, Inc., Shelton, CT, USA) was used for the speciation of soluble Cr (III) and soluble Cr (VI). The separation was accomplished by interaction of the chromium species with the different components of the mobile phase. Cr (III) formed a complex with EDTA, i.e. retained on the column, while Cr (VI) existed in the solutions as dichromate. Alkaline extraction (2% KOH and 3% Na2CO3) and anion exchange column (PRP-X100, PEEK, Hamilton) were used for the separation of the total Cr (VI). The results of the determination of Cr (VI) were confirmed by the analysis of the certified reference material BCR CRM 545 (Cr (VI) in welding dust). The results obtained for the certified material (40.2±0.6 g kg(-1)) and the values recorded in the examined samples (40.7±0.6 g kg(-1)) were highly consistent. This analytical method was applied for the determination of chromium in the samples in the workplace air collected onto glass (Whatman, Ø 37 mm) and membrane filters (Sartorius, 0.8 μm, Ø 37 mm). High performance liquid chromatography with inductively coupled plasma mass spectrometry is a remarkably powerful and versatile technique for determination of chromium species in welding fume at workplace air. PMID:24209303

  15. Space Shuttle Day-of-Launch Trajectory Design Operations

    NASA Technical Reports Server (NTRS)

    Harrington, Brian E.

    2011-01-01

    A top priority of any launch vehicle is to insert as much mass into the desired orbit as possible. This requirement must be traded against vehicle capability in terms of dynamic control, thermal constraints, and structural margins. The vehicle is certified to specific structural limits which will yield certain performance characteristics of mass to orbit. Some limits cannot be certified generically and must be checked with each mission design. The most sensitive limits require an assessment on the day-of-launch. To further minimize vehicle loads while maximizing vehicle performance, a day-of-launch trajectory can be designed. This design is optimized according to that day s wind and atmospheric conditions, which increase the probability of launch. The day-of-launch trajectory design and verification process is critical to the vehicle s safety. The Day-Of-Launch I-Load Update (DOLILU) is the process by which the National Aeronautics and Space Administration's (NASA) Space Shuttle Program tailors the vehicle steering commands to fit that day s environmental conditions and then rigorously verifies the integrated vehicle trajectory s loads, controls, and performance. This process has been successfully used for almost twenty years and shares many of the same elements with other launch vehicles that execute a day-of-launch trajectory design or day-of-launch trajectory verification. Weather balloon data is gathered at the launch site and transmitted to the Johnson Space Center s Mission Control. The vehicle s first stage trajectory is then adjusted to the measured wind and atmosphere data. The resultant trajectory must satisfy loads and controls constraints. Additionally, these assessments statistically protect for non-observed dispersions. One such dispersion is the change in the wind from the last measured balloon to launch time. This process is started in the hours before launch and is repeated several times as the launch count proceeds. Should the trajectory design

  16. Optimization of interplanetary trajectories to Mars via electrical propulsion

    NASA Astrophysics Data System (ADS)

    Williams, Powtawche Neengay

    Although chemical rocket propulsion is widely used in space transportation, large amounts of propellant mass limit designs for spacecraft missions to Mars. Electrical propulsion, which requires a smaller propellant load, is an alternative propulsion system that can be used for interplanetary flight. After the recent successes of the NASA Deep Space 1 spacecraft and the ESA SMART 1 spacecraft, which incorporate an electrical propulsion system, there is a strong need for trajectory tools to support these systems. This thesis describes the optimization of interplanetary trajectories from Earth to Mars for spacecraft utilizing low-thrust electrical propulsion systems. It is assumed that the controls are the thrust direction and the thrust setting. Specifically, the minimum time and minimum propellant problems are studied and solutions are computed with the sequential gradient-restoration algorithm (SGRA). The results indicate that, when the thrust direction and thrust setting are simultaneously optimized, the minimum time and minimum propellant solutions are not identical. For minimum time, it is found that the thrust setting must be at the maximum value; also, the thrust direction has a normal component with a switch at midcourse from upward to downward. This changes the curvature of the trajectory, has a beneficial effect on time, but a detrimental effect on propellant mass; indeed, the propellant mass ratio of the minimum time solution is about twice that of the Hohmann transfer solution. Thus, the minimum time solution yields a rather inefficient trajectory. For minimum propellant consumption, it is found that the best thrust setting is bang-zero-bang (maximum thrust, followed by coasting, followed by maximum thrust) and that the best thrust direction is tangent to the trajectory. This is a rather efficient trajectory; to three significant digits, the associated mass ratio is the same as that of the Hohmann transfer solution, even for thrust-to-weight ratios of

  17. Social trajectory and body image satisfaction in childbearing women.

    PubMed

    Henriques, Ana; Alves, Luís; Alves, Elisabete; Silva, Susana; Barros, Henrique; Azevedo, Ana

    2015-06-01

    Advantaged socioeconomic position (SEP) is associated with lower body image satisfaction (BIS) among women. However, motherhood and social trajectory (an individual's path from childhood SEP to adulthood SEP) could change this relationship. We aimed to assess the association between social trajectory and BIS immediately before getting pregnant in primiparous and multiparous mothers of a birth cohort. The birth cohort Generation XXI was assembled after delivery, in Porto, in 2005-2006. This analysis includes 5,470 women. Women's and their parents' education were used as indicators of adulthood and childhood SEP, respectively. Social trajectory was classified as stable-high, upward, stable-low, downward, according to both education variables. BIS was assessed with Stunkard silhouettes immediately after birth as the difference between perceived body size before the index pregnancy and ideal body size. Odds ratios (OR) between social trajectory and BIS were computed using multinomial logistic regression (women satisfied with body image were the outcome reference category), adjusting for age and prepregnancy body mass index. In primiparous women, no association was found between childhood SEP, adulthood SEP or social trajectory and feeling too small or too large regarding their ideal figure. Multiparous women with a downward social trajectory presented a higher likelihood of dissatisfaction [too small: adjusted OR 2.21, 95 % confidence interval (95 % CI) 1.10-4.46; too large: adjusted OR 1.64, 95 % CI 1.07-2.51]. Downward social trajectory was associated with a higher likelihood of dissatisfaction with body image in multiparae, while there was no effect among primiparae. PMID:25359096

  18. Social trajectory and body image satisfaction in childbearing women.

    PubMed

    Henriques, Ana; Alves, Luís; Alves, Elisabete; Silva, Susana; Barros, Henrique; Azevedo, Ana

    2015-06-01

    Advantaged socioeconomic position (SEP) is associated with lower body image satisfaction (BIS) among women. However, motherhood and social trajectory (an individual's path from childhood SEP to adulthood SEP) could change this relationship. We aimed to assess the association between social trajectory and BIS immediately before getting pregnant in primiparous and multiparous mothers of a birth cohort. The birth cohort Generation XXI was assembled after delivery, in Porto, in 2005-2006. This analysis includes 5,470 women. Women's and their parents' education were used as indicators of adulthood and childhood SEP, respectively. Social trajectory was classified as stable-high, upward, stable-low, downward, according to both education variables. BIS was assessed with Stunkard silhouettes immediately after birth as the difference between perceived body size before the index pregnancy and ideal body size. Odds ratios (OR) between social trajectory and BIS were computed using multinomial logistic regression (women satisfied with body image were the outcome reference category), adjusting for age and prepregnancy body mass index. In primiparous women, no association was found between childhood SEP, adulthood SEP or social trajectory and feeling too small or too large regarding their ideal figure. Multiparous women with a downward social trajectory presented a higher likelihood of dissatisfaction [too small: adjusted OR 2.21, 95 % confidence interval (95 % CI) 1.10-4.46; too large: adjusted OR 1.64, 95 % CI 1.07-2.51]. Downward social trajectory was associated with a higher likelihood of dissatisfaction with body image in multiparae, while there was no effect among primiparae.

  19. Canonical Transformations of Kepler Trajectories

    ERIC Educational Resources Information Center

    Mostowski, Jan

    2010-01-01

    In this paper, canonical transformations generated by constants of motion in the case of the Kepler problem are discussed. It is shown that canonical transformations generated by angular momentum are rotations of the trajectory. Particular attention is paid to canonical transformations generated by the Runge-Lenz vector. It is shown that these…

  20. Distance Education: Educational Trajectory Control

    ERIC Educational Resources Information Center

    Isaev, Andrey; Kravets, Alla; Isaeva, Ludmila; Fomenkov, Sergey

    2013-01-01

    Distance education has become a rather popular form of education recently. The advantages of this form are obvious and well-known. They include asynchronous learning, individualized learning trajectories and convenient case technologies. However, the distance form of education is not able to form the trainee's hands-on experience, especially…

  1. Interplanetary Trajectories, Encke Method (ITEM)

    NASA Technical Reports Server (NTRS)

    Whitlock, F. H.; Wolfe, H.; Lefton, L.; Levine, N.

    1972-01-01

    Modified program has been developed using improved variation of Encke method which avoids accumulation of round-off errors and avoids numerical ambiguities arising from near-circular orbits of low inclination. Variety of interplanetary trajectory problems can be computed with maximum accuracy and efficiency.

  2. Visiting Vehicle Ground Trajectory Tool

    NASA Technical Reports Server (NTRS)

    Hamm, Dustin

    2013-01-01

    The International Space Station (ISS) Visiting Vehicle Group needed a targeting tool for vehicles that rendezvous with the ISS. The Visiting Vehicle Ground Trajectory targeting tool provides the ability to perform both realtime and planning operations for the Visiting Vehicle Group. This tool provides a highly reconfigurable base, which allows the Visiting Vehicle Group to perform their work. The application is composed of a telemetry processing function, a relative motion function, a targeting function, a vector view, and 2D/3D world map type graphics. The software tool provides the ability to plan a rendezvous trajectory for vehicles that visit the ISS. It models these relative trajectories using planned and realtime data from the vehicle. The tool monitors ongoing rendezvous trajectory relative motion, and ensures visiting vehicles stay within agreed corridors. The software provides the ability to update or re-plan a rendezvous to support contingency operations. Adding new parameters and incorporating them into the system was previously not available on-the-fly. If an unanticipated capability wasn't discovered until the vehicle was flying, there was no way to update things.

  3. Classical Trajectories and Quantum Spectra

    NASA Technical Reports Server (NTRS)

    Mielnik, Bogdan; Reyes, Marco A.

    1996-01-01

    A classical model of the Schrodinger's wave packet is considered. The problem of finding the energy levels corresponds to a classical manipulation game. It leads to an approximate but non-perturbative method of finding the eigenvalues, exploring the bifurcations of classical trajectories. The role of squeezing turns out decisive in the generation of the discrete spectra.

  4. Trajectory-Based Loads for the Ares I-X Test Flight Vehicle

    NASA Technical Reports Server (NTRS)

    Vause, Roland F.; Starr, Brett R.

    2011-01-01

    In trajectory-based loads, the structural engineer treats each point on the trajectory as a load case. Distributed aero, inertial, and propulsion forces are developed for the structural model which are equivalent to the integrated values of the trajectory model. Free-body diagrams are then used to solve for the internal forces, or loads, that keep the applied aero, inertial, and propulsion forces in dynamic equilibrium. There are several advantages to using trajectory-based loads. First, consistency is maintained between the integrated equilibrium equations of the trajectory analysis and the distributed equilibrium equations of the structural analysis. Second, the structural loads equations are tied to the uncertainty model for the trajectory systems analysis model. Atmosphere, aero, propulsion, mass property, and controls uncertainty models all feed into the dispersions that are generated for the trajectory systems analysis model. Changes in any of these input models will affect structural loads response. The trajectory systems model manages these inputs as well as the output from the structural model over thousands of dispersed cases. Large structural models with hundreds of thousands of degrees of freedom would execute too slowly to be an efficient part of several thousand system analyses. Trajectory-based loads provide a means for the structures discipline to be included in the integrated systems analysis. Successful applications of trajectory-based loads methods for the Ares I-X vehicle are covered in this paper. Preliminary design loads were based on 2000 trajectories using Monte Carlo dispersions. Range safety loads were tied to 8423 malfunction turn trajectories. In addition, active control system loads were based on 2000 preflight trajectories using Monte Carlo dispersions.

  5. Available Instruments for Analyzing Molecular Dynamics Trajectories.

    PubMed

    Likhachev, I V; Balabaev, N K; Galzitskaya, O V

    2016-01-01

    Molecular dynamics trajectories are the result of molecular dynamics simulations. Trajectories are sequential snapshots of simulated molecular system which represents atomic coordinates at specific time periods. Based on the definition, in a text format trajectory files are characterized by their simplicity and uselessness. To obtain information from such files, special programs and information processing techniques are applied: from molecular dynamics animation to finding characteristics along the trajectory (versus time). In this review, we describe different programs for processing molecular dynamics trajectories. The performance of these programs, usefulness for analyses of molecular dynamics trajectories, strong and weak aspects are discussed. PMID:27053964

  6. Experimental nonlocal and surreal Bohmian trajectories.

    PubMed

    Mahler, Dylan H; Rozema, Lee; Fisher, Kent; Vermeyden, Lydia; Resch, Kevin J; Wiseman, Howard M; Steinberg, Aephraim

    2016-02-01

    Weak measurement allows one to empirically determine a set of average trajectories for an ensemble of quantum particles. However, when two particles are entangled, the trajectories of the first particle can depend nonlocally on the position of the second particle. Moreover, the theory describing these trajectories, called Bohmian mechanics, predicts trajectories that were at first deemed "surreal" when the second particle is used to probe the position of the first particle. We entangle two photons and determine a set of Bohmian trajectories for one of them using weak measurements and postselection. We show that the trajectories seem surreal only if one ignores their manifest nonlocality.

  7. Available Instruments for Analyzing Molecular Dynamics Trajectories

    PubMed Central

    Likhachev, I. V.; Balabaev, N. K.; Galzitskaya, O. V.

    2016-01-01

    Molecular dynamics trajectories are the result of molecular dynamics simulations. Trajectories are sequential snapshots of simulated molecular system which represents atomic coordinates at specific time periods. Based on the definition, in a text format trajectory files are characterized by their simplicity and uselessness. To obtain information from such files, special programs and information processing techniques are applied: from molecular dynamics animation to finding characteristics along the trajectory (versus time). In this review, we describe different programs for processing molecular dynamics trajectories. The performance of these programs, usefulness for analyses of molecular dynamics trajectories, strong and weak aspects are discussed. PMID:27053964

  8. Experimental nonlocal and surreal Bohmian trajectories.

    PubMed

    Mahler, Dylan H; Rozema, Lee; Fisher, Kent; Vermeyden, Lydia; Resch, Kevin J; Wiseman, Howard M; Steinberg, Aephraim

    2016-02-01

    Weak measurement allows one to empirically determine a set of average trajectories for an ensemble of quantum particles. However, when two particles are entangled, the trajectories of the first particle can depend nonlocally on the position of the second particle. Moreover, the theory describing these trajectories, called Bohmian mechanics, predicts trajectories that were at first deemed "surreal" when the second particle is used to probe the position of the first particle. We entangle two photons and determine a set of Bohmian trajectories for one of them using weak measurements and postselection. We show that the trajectories seem surreal only if one ignores their manifest nonlocality. PMID:26989784

  9. Experimental nonlocal and surreal Bohmian trajectories

    PubMed Central

    Mahler, Dylan H.; Rozema, Lee; Fisher, Kent; Vermeyden, Lydia; Resch, Kevin J.; Wiseman, Howard M.; Steinberg, Aephraim

    2016-01-01

    Weak measurement allows one to empirically determine a set of average trajectories for an ensemble of quantum particles. However, when two particles are entangled, the trajectories of the first particle can depend nonlocally on the position of the second particle. Moreover, the theory describing these trajectories, called Bohmian mechanics, predicts trajectories that were at first deemed “surreal” when the second particle is used to probe the position of the first particle. We entangle two photons and determine a set of Bohmian trajectories for one of them using weak measurements and postselection. We show that the trajectories seem surreal only if one ignores their manifest nonlocality. PMID:26989784

  10. [Mathematical modeling of the kinematics of a pilot's head while catapulting into an air stream].

    PubMed

    Kharchenko, V I; Golovleva, N V; Konakhevich, Iu G; Liapin, V A; Mar'in, A V

    1987-01-01

    The trajectories of head movements in the helmet and velocities of impact contact with the seat and anterior of the cockpit were calculated as applied to every stage of the catapulting process and mass-inertia parameters of helmets taken into account. Kinematic models were used to describe biomechanic parameters of the head-neck system. Special attention was given to the case of catapulting to the air flow. The effect upon the nod of aerodynamic forces acting on the human body and the catapult ejection seat at air flow velocities of 700-800 and 1300 km/hr was calculated. PMID:3586592

  11. Development and Evaluation of an Externally Air-Cooled Low-Flow torch and the Attenuation of Space Charge and Matrix Effects in Inductively Coupled Plasma Mass Spectrometry

    SciTech Connect

    Praphairaksit, N.

    2000-09-12

    An externally air-cooled low-flow torch has been constructed and successfully demonstrated for applications in inductively coupled plasma mass spectrometry (ICP-MS). The torch is cooled by pressurized air flowing at {approximately}70 L/min through a quartz air jacket onto the exterior of the outer tube. The outer gas flow rate and operating RF forward power are reduced considerably. Although plasmas can be sustained at the operating power as low as 400 W with a 2 L/min of outer gas flow, somewhat higher power and outer gas flows are advisable. A stable and analytical useful plasma can be obtained at 850 W with an outer gas flow rate of {approximately}4 L/min. Under these conditions, the air-cooled plasma produces comparable sensitivities, doubly charged ion ratios, matrix effects and other analytical merits as those produced by a conventional torch while using significantly less argon and power requirements. Metal oxide ion ratios are slightly higher with the air-cooled plasma but can be mitigated by reducing the aerosol gas flow rate slightly with only minor sacrifice in analyte sensitivity. A methodology to alleviate the space charge and matrix effects in ICP-MS has been developed. A supplemental electron source adapted from a conventional electron impact ionizer is added to the base of the skimmer. Electrons supplied from this source downstream of the skimmer with suitable amount and energy can neutralize the positive ions in the beam extracted from the plasma and diminish the space charge repulsion between them. As a result, the overall ion transmission efficiency and consequent analyte ion sensitivities are significantly improved while other important analytical aspects, such as metal oxide ion ratio, doubly charged ion ratio and background ions remain relatively unchanged with the operation of this electron source. This technique not only improves the ion transmission efficiency but also minimizes the matrix effects drastically. The matrix-induced suppression

  12. Distributed Trajectory Flexibility Preservation for Traffic Complexity Mitigation

    NASA Technical Reports Server (NTRS)

    Idris, Husni; Wing, David; Delahaye, Daniel

    2009-01-01

    The growing demand for air travel is increasing the need for mitigation of air traffic congestion and complexity problems, which are already at high levels. At the same time new information and automation technologies are enabling the distribution of tasks and decisions from the service providers to the users of the air traffic system, with potential capacity and cost benefits. This distribution of tasks and decisions raises the concern that independent user actions will decrease the predictability and increase the complexity of the traffic system, hence inhibiting and possibly reversing any potential benefits. In answer to this concern, the authors propose the introduction of decision-making metrics for preserving user trajectory flexibility. The hypothesis is that such metrics will make user actions naturally mitigate traffic complexity. In this paper, the impact of using these metrics on traffic complexity is investigated. The scenarios analyzed include aircraft in en route airspace with each aircraft meeting a required time of arrival in a one-hour time horizon while mitigating the risk of loss of separation with the other aircraft, thus preserving its trajectory flexibility. The experiments showed promising results in that the individual trajectory flexibility preservation induced self-separation and self-organization effects in the overall traffic situation. The effects were quantified using traffic complexity metrics based on Lyapunov exponents and traffic proximity.

  13. Analysis of Trajectory Flexibility Preservation Impact on Traffic Complexity

    NASA Technical Reports Server (NTRS)

    Idris, Husni; El-Wakil, Tarek; Wing, David J.

    2009-01-01

    The growing demand for air travel is increasing the need for mitigation of air traffic congestion and complexity problems, which are already at high levels. At the same time new information and automation technologies are enabling the distribution of tasks and decisions from the service providers to the users of the air traffic system, with potential capacity and cost benefits. This distribution of tasks and decisions raises the concern that independent user actions will decrease the predictability and increase the complexity of the traffic system, hence inhibiting and possibly reversing any potential benefits. In answer to this concern, the authors proposed the introduction of decision-making metrics for preserving user trajectory flexibility. The hypothesis is that such metrics will make user actions naturally mitigate traffic complexity. In this paper, the impact of using these metrics on traffic complexity is investigated. The scenarios analyzed include aircraft in en route airspace with each aircraft meeting a required time of arrival in a one-hour time horizon while mitigating the risk of loss of separation with the other aircraft, thus preserving its trajectory flexibility. The experiments showed promising results in that the individual trajectory flexibility preservation induced self-separation and self-organization effects in the overall traffic situation. The effects were quantified using traffic complexity metrics, namely dynamic density indicators, which indicated that using the flexibility metrics reduced aircraft density and the potential of loss of separation.

  14. Thermally-driven advections of aerosol-rich air masses to an Alpine valley: Theoretical considerations and experimental evidences

    NASA Astrophysics Data System (ADS)

    Diémoz, Henri; Magri, Tiziana; Pession, Giordano; Zublena, Manuela; Campanelli, Monica; Gobbi, Gian Paolo; Barnaba, Francesca; Di Liberto, Luca; Dionisi, Davide

    2016-04-01

    A CHM-15k laser radar (lidar) was installed in April 2015 at the solar observatory of the Environmental Protection Agency (ARPA) of the Aosta Valley (Northern Italy, 45.74N, 7.36E, 560 m a.s.l.). The instrument operates at 1064 nm, is capable of mapping the vertical profile of aerosols and clouds up to the tropopause and is part of the Alice-net ceilometers network (www.alice-net.eu). The site is in a large Alpine valley floor, in a semi-rural context. Among the most interesting cases observed in the first months of operation, several days characterised by weak synoptic circulation and well-developed, thermally-driven up-valley winds are accompanied by the appearance of a thick aerosol layer in the afternoon. The phenomenon is frequent in Spring and Summer and is likely to be related to easterly airmass advections from polluted sites (e.g., the Po basin) rather than to local emissions. To test this hypothesis, the following method was adopted. First, some case studies were selected and the respective meteorological fields were analysed based on both observations at ground and the high-resolution output of the nonhydrostatic limited-area atmospheric prediction model maintained by the COnsortium for Small-scale MOdelling (COSMO) over the complex orography of the domain. Then, to evaluate the dynamics of the aerosol diffusion in the valley, the chemical transport 2D/3D eulerian Flexible Air quality Regional Model (FARM) was run. Finally, the three-dimensional output of the model was compared to the vertically-resolved aerosol field derived from the lidar-ceilometer soundings. The effects of up-slope winds, and the resulting subsidence along the main axis of the valley, is hypothesised to break up the aerosol layer close to the ground in the middle of the day and to drag the residual layer down into the mixing layer. The measurements by a co-located sun/sky photometer operating in the framework of the EuroSkyRad (ESR) network were additionally analysed to detect any

  15. A high-fidelity multiphysics model for the new solid oxide iron-air redox battery part I: Bridging mass transport and charge transfer with redox cycle kinetics

    SciTech Connect

    Jin, XF; Zhao, X; Huang, K

    2015-04-15

    A high-fidelity two-dimensional axial symmetrical multi-physics model is described in this paper as an effort to simulate the cycle performance of a recently discovered solid oxide metal-air redox battery (SOMARB). The model collectively considers mass transport, charge transfer and chemical redox cycle kinetics occurring across the components of the battery, and is validated by experimental data obtained from independent research. In particular, the redox kinetics at the energy storage unit is well represented by Johnson-Mehl-Avrami-Kolmogorov (JIVIAK) and Shrinking Core models. The results explicitly show that the reduction of Fe3O4 during the charging cycle limits the overall performance. Distributions of electrode potential, overpotential, Nernst potential, and H-2/H2O-concentration across various components of the battery are also systematically investigated. (C) 2015 Elsevier B.V. All rights reserved.

  16. Engineering correlations of variable-property effects on laminar forced convection mass transfer for dilute vapor species and small particles in air

    NASA Tech