• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 20
  • 18
  • 13
  • 12
  • 7
  • 5
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 91
  • 26
  • 21
  • 20
  • 19
  • 14
  • 13
  • 11
  • 10
  • 10
  • 10
  • 10
  • 9
  • 8
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Etude de la source et du transport des aérosols marins en zone côtière méditerranéenne / Study of the source and the transport of Sea-spays in the Mediterranean Coastal Zone

Demoisson, Ambre 17 March 2014 (has links)
La connaissance de la source et du transport atmosphérique de l’aérosol marin est primordiale pour mieux comprendre un grand nombre de processus physico-chimiques régissant les propriétés de la basse troposphère. C’est dans ce cadre que s’inscrit cette thèse dont l’objectif principal concerne la modélisation de la génération et du transport des aérosols marins en zone côtière Méditerranéenne. Cette étude a permis notamment l’amélioration du modèle de transport MACMod à partir d’un travail sur les conditions aux surfaces frontières. Une formulation de la fonction source spécifique à la région méditerranéenne nord-occidentale a été déterminée et certains effets des transformations subies par les particules issues de la production primaire au cours de leur transport atmosphérique ont été analysés. De plus, dans le but de mieux tenir compte du cas des zones anthropisées pour les conditions aux limites du modèle, un travail sur l’implémentation du code CHIMERE sur la région méditerranéenne a été initialisé. Enfin, une dernière partie a été consacrée à l’adaptation du modèle MACMod à la prévision de la qualité de l’air et le suivi des concentrations de PM2.5 et PM10. / The knowledge of both the source and atmospheric transport of marine aerosols is needed for a better understanding of a large number of physicochemical processes that control the lower troposphere properties. In this context, the present work deals with the modelization of the generation and atmospheric transport of marine aerosols in the Mediterranean coastal zone. In particular, this study allowed improvement of the aerosol transport model MACMod on the basis of a specific work on the boundary conditions. A new formulation of the sea-spray source function has been determined for the northern Mediterranean and effects of the transformations of the sea-spray particles during their atmospheric transport were identified. In addition, to better take into account the influence of the anthropogenic zones for the boundary conditions, the implementation of the CHIMERE model on the study area was made. Finally, a last part of the thesis was dedicated to the use of the MACMod model for the air quality forecasting and the survey of the PM2.5 and PM10 concentrations.
2

Dubbdäckens vara eller icke vara : Orsaken till dubbdäcksförbud i Uppsala kommun

Vikström, Anton January 2013 (has links)
No description available.
3

Effets du climat et de la pollution de l'air sur la santé respiratoire à Tunis / The impact of weather and air pollution on respiratory health in Tunis

Ben Romdhane, Safa 12 December 2017 (has links)
Le Grand-Tunis présente une vulnérabilité face à la pollution atmosphérique compte tenu des fortes densités de population et des nombreuses infrastructures caractérisant son territoire. L’ozone (O3) et les particules en suspension (PM10) dépassent fréquemment les normes tunisiennes relatives à ces polluants. Quant aux normes internationales fixées par l’OMS (Organisation Mondiale de la Santé), elles n’ont été respectées que rarement. L’appareil respiratoire constitue une voie d’exposition privilégiée aux agressions en rapport avec l’environnement. De nombreuses pathologies pulmonaires sont directement liées à l’inhalation des polluants dans l’atmosphère. Les influences des mécanismes climatiques sur la santé respiratoire sont très étendues également, notamment les épisodes météorologiques extrêmes appelés aussi paroxysmes météorologiques.L’objectif principal de cette thèse est de caractériser l’impact des facteurs environnementaux, climat et polluants atmosphériques sur la santé respiratoire dans le Grand-Tunis. Nous avons choisi de quantifier cette relation à partir des indicateurs biométéorologiques et des seuils absolus de stress météorologique, spécifiques au climat tunisois, et de la qualité de l’air pour prévoir des épisodes à risque pour la santé respiratoire. Cela est fait à partir des extrêmes météorologiques des paramètres les plus irritants pour la santé respiratoire : la température, l’humidité relative de l’air et la vitesse maximale du vent. Nous avons aussi établi des normes réalistes pour la qualité de l’air, relatives à l’O3 et aux PM10, identifiant les seuils critiques de surplus des hospitalisations dans le Grand-Tunis et qui peuvent être appliquées dans tout le pays. Compte tenu de l’effet de certains paramètres climatiques sur la dispersion des polluants dans l’atmosphère, nous avons aussi étudié la relation entre les paramètres météorologiques et les polluants d’O3 et de PM10. Les résultats de cette étude révèlent que, durant toute l’année, les tunisois sont confrontés au moins à un risque environnemental : la pollution photochimique et les vagues de chaleur, très répandues durant la saison chaude ; durant la saison froide, c’est le risque du froid et de la pollution particulaire ; et pendant les intersaisons, c’est la pollution biologique, avec les pollens, qui est le risque le plus important. Toutefois, l’exposition à court terme à ces risques, sur l’aggravation de la maladie respiratoire ou l’irritation du système respiratoire sont bien réelles. Cette recherche montre que le développement et l’aggravation des maladies respiratoires semblent découler d’une interaction complexe entre divers facteurs individuels et environnementaux. Ils sont essentiellement en relation avec le temps, la qualité de l’air et l’atopie. L’importance de ces facteurs varie selon la maladie considérée. Par ailleurs, le faible niveau socioéconomique de la famille augmente la probabilité d’être exposé à plusieurs de ces facteurs de risque. À cela s’ajoutent les facteurs comportementaux tels que l’alcool, le tabagisme actif et passif. / The Greater metropolitan area of Tunis, often referred to as Grand Tunis or Tunis, presents a vulnerability to air pollution due to the high concentrations of population and the infrastructures characterizing its territory. Ozone (O3) and particles (PM10) often exceed the Tunisian thresholds for these pollutants. As for the international standards set by the WHO (world health organization), they have not been met infrequently.The respiratory tract is a preferred route of exposure to aggressions related to the environment. Many lung diseases are directly linked to inhalation of pollutants in the atmosphere. The influences of climate mechanisms on respiratory health are also very extensive, including extreme weather events, also called weather paroxysms.The main objective of this thesis was to characterize the impact of environmental factors, climate and atmospheric pollutants on respiratory health in Grand Tunis. We have chosen to quantify this relationship from the biometeorological indicators and absolute thresholds of meteorological stress, specific Tunisian climate, and air quality to predict episodes at risk for respiratory health and thresholds of weather variables and air quality resulting in excess hospital admissions for respiratory causes. And this from the climate extremes of the parameters affecting the respiratory health : temperature, relative humidity and maximum wind speed. We, too, set realistic standards for air quality, relative to O3 and PM10, identifying critical thresholds excess hospitalizations in Grand Tunis and can be applied throughout the country. Given the effect of some climatic parameters on the dispersion of pollutants in the atmosphere, we also studied the relationship between climatic parameters and pollutants of O3 and PM10. The results of this study reveal that, throughout the year, Tunisians are confronted with at least an environmental risk : photochemical pollution and heat waves, which are very responsive during the hot season ; during the cold season, it is the risk of cold and particulate pollution; and during the off-season, biological pollution, together with pollen, is more at risk. However, short-term exposure to these risks, the worsening of the respiratory illness or irritation of the respiratory system is real. This study showed that the development and worsening of respiratory diseases appear to result from a complex interplay of individual and environmental factors. They are mainly in relation to time, air quality and atopy. The importance of these factors varies the respective disease. Moreover, the low socioeconomic status of the family increases the likelihood of being exposed to more of these risk factors. Added to this are behavioral factors such as alcohol, active and passive smoking.
4

A PM10 emission factor for free stall dairies

Goodrich, Lee Barry 16 August 2006 (has links)
Ambient concentration measurements of total suspended particulate (TSP) were made at a commercial dairy in central Texas during the summers of 2002 and 2003. The facility consisted of both open pen housing and free-stall structures to accommodate approximately 1840 head of milking cattle. The field sampling results were used in the EPA approved dispersion model Industrial Source Complex Short Term version 3 (ISCST-v3) to estimate emission fluxes and ultimately a seasonally corrected emission factor for a free-stall dairy. Ambient measurements of TSP concentrations for sampling periods ranging from 2 to 6 hours were recorded during the summer of 2002. The mean upwind concentration was 115µg/m3 with a maximum of 231µg/m3 and a minimum of 41.4µg/m3. The mean net downwind TSP concentration was 134µg/m3 with a maximum of 491µg/m3 and a minimum of 14µg/m3. Field sampling at this same dairy in the summer of 2003 yielded significantly more 2 to 6 hour TSP concentration measurements. The mean upwind TSP concentration was 76µg/m3 with a maximum concentration of 154µg/m3. The mean net downwind TSP concentration was 118µg/m3 with a maximum of 392µg/m3 and a minimum of 30µg/m3. The particle size distributions (PSD) of the PM on the downwind TSP filters was determined using the Coulter Counter Multisizer. The results of this process was a representative dairy PM PSD with 28% of TSP emissions being PM10. The reported PM10 24-hour emission factors were 4.7 kg/1000hd/day for the free-stall areas of the facility and 11.7 kg/1000hd/day for the open pen areas of the dairy. These emission factors were uncorrected for rainfall events. Corrections for seasonal dust suppression events were made for the San Joaquin Valley of California and the panhandle region of Texas. Using historical rainfall and ET data for central California, the seasonally corrected PM10 emission factor is 3.6kg/1000hd/day for the free-stalls, and 8.7kg/1000hd/day for the open pens. For Texas, the seasonally corrected emission factor is 3.7kg/1000hd/day for the free-stall areas and 9.2kg/1000hd/day for the open lot areas.
5

Contaminantes Atmosféricos Particulados: Evaluación de las fuentes de origen y de su contribución a la contaminación atmosférica en el clúster cerámico de Castellón.

Soriano Rodrí­guez, Maria Desamparados 05 December 2012 (has links)
El cumplimiento de los valores límite para las partículas atmosféricas en suspensión es un reto para la Unión Europea, por este motivo en 2008, la Unión Europea aprobó la Directiva 2008/50/CE sobre calidad del aire ambiente y una atmósfera más limpia en Europa donde, además de establecer el valor límite para las partículas PM10 se establece por primera vez, en la legislación europea, un valor límite para las partículas PM2,5. Las emisiones procedentes de los clústers cerámicos, en su mayoría partículas, constituyen un problema ambiental. Por este motivo, el presente trabajo se centra en la provincia de Castellón, ya que en ella se encuentra el mayor núcleo de producción cerámica en España. Con el fin de analizar la contaminación del aire ambiente debida a las partículas atmosféricas presentes en el área de muestreo, el presente trabajo se ha dividido en cuatro partes, en las que se ha llevado a cabo un estudio de los niveles de distintas fracciones: fracción PM10, fracción PM2,5 y fracción sedimentable. Además se ha realizado un análisis químico de las muestras (PM2,5 y fracción soluble de las partículas sedimentables), para tratar de identificar las posibles fuentes antropogénicas presentes en el área de estudio, así como, la influencia que estas fuentes tienen sobre los niveles de partículas atmosféricas y sobre los niveles de contaminación del suelo.
6

Application of Artificial Neural Network on The Prediction of Ambient Air Quality

Lin, Yat-Chen 30 July 2002 (has links)
The air quality in Kaohsiung and Ping-Dong district is the worst in Taiwan. The air pollution episodes in Kaohsiung are attributed to high concentrations of PM10 and O3. Among them, over half of the episodes result from PM10. In addition to Pollutant Standards Index (PSI), atmospheric visibility is also an indicator of ambient air quality. Citizens always complain about the impairment of visibility because it can be visualized directly. Visibility is closely correlated to both air pollutants and meteorological condition. Extinction of visible light by fine particles is the major reason for visibility impairment. In this study, an artificial neural network was applied to predict the concentration of PM10 and atmospheric visibility. The objectives of this study were to investigate the effects of meteorological factor and air pollutants on visibility and to apply artificial neural network to predict the concentration of PM10 and atmospheric visibility. The measured PM10 data were divided into two parts (i.e. summer and winter, ) to understand whether different season affect the prediction of PM10 concentration. The modeling results showed that the optimum input variables included the PM10 concentration, atmospheric pressure, surface radiation, relative humidity, atmospheric temperature, and cloud condition. The network outputs showed high correlation with measured PM10 concentration (R=0.876) in the whole-year set. Furthermore, the prediction of summer set also showed high correlation with measured PM10 concentration (R=0.753). The winter set demonstrated the worse prediction among three sets, and showed medium correlation with measured PM10 concentration (R=0.553). The visibility network test was conducted by two stages. The first stage (set-1~set-3) showed that relative humidity, atmospheric temperature, and cloud condition were the most important meteorological factors, while PM10, O3, and NO3 were the most important air pollutants on the prediction of atmospheric visibility. The prediction of set-1 considering only meteorological factors was the worst (R=0.586), while set-3 was the best and showed medium correlation with measured atmospheric visibility (R=0.633). The second stage (set-4 and set-5) increased the hidden neuron numbers and input variables, and added atmospheric visibility in the input variables. Although the correlation coefficients between predicted and measured data did not increase, the prediction of atmospheric visibility had significant improvement. Finally, a short-term prediction of PM10 and atmospheric visibility was conducted and validated by the level of PSI values and atmospheric visibility. Prediction results showed that the accuracy of PM10 prediction was 76.9%, while the prediction of atmospheric visibility by set-3 network demonstrated an accuracy of 76.9%. Moreover, no significant difference of prediction was detected by using either three-level or five-level visibility systems.
7

Hur naturlig är luften vi andas? : En studie i erfarenheter av hantering av luftkvalitetsproblem i två svenska kommuner. / How natural is the air we breathe? : A study about experiences of the management of air quality problems in two Swedish municipalities.

Nilsen, Freja, Swebilius, Maria January 2015 (has links)
Genom att undersöka hur två olika kommuner i Sverige arbetar med och hanterar de luftkvalitetsproblem som uppstår i städer på grund av trafiksektorn, främst på gator och vägar, syftar studien till att identifiera problem och lösningar kring arbetet med åtgärdsprogrammen. Genom kvalitativa intervjuer med utvalda nyckelpersoner på kommunerna identifierades erfarenheter av att arbeta med luftkvalitetsfrågan. Dessa erfarenheter ställdes mot tidigare forskning för att belysa ifall de tillvägagångssätt kommunerna använder sig av är någonting som är väl beprövat eller om de är nya metoder. Resultatet av studien visade på ett par viktiga faktorer som behövs för att få bukt med luftkvalitetsproblemen; ekonomi, forskning samt inställning hos kommuninvånare och kommunalanställda. Det framgick ifrån informanternas argument att de åtgärder som är svårast att implementera i kommunerna berör frivilliga beteendeförändringar hos invånarna eftersom många helst inte vill förändra sina dagliga resmönster. De åtgärder som är enklast att införa är sådana som förbjuder vissa handlingar, till exempel dubbdäckförbud på vissa gator, då det inte krävs ombyggnation eller nybyggnation av staden. / By investigating how two different municipalities in Sweden are working with and managing problems regarding air pollution in cities due to the traffic sector, mainly on streets and roads, this study aims to identify problems and solutions concerning the work of the action programs. Through qualitative interviews with key people working in the municipalities, we identified experiences of working with air pollution. These experiences were compared to previous research to illustrate if the approaches the municipalities use is something that have been used before, or if these methods are new. The results of the study identified a couple of important factors needed to overcome problems regarding air pollution; economy, research and attitudes among residents and employees in municipalities. The arguments of the respondents made it clear that the hardest measures to implement are those considering voluntary behavioral changes, since many people are reluctant to change their daily travel patterns. The easiest measures to implement are those that prohibit certain acts, for example banning studded tyres on certain streets, since these measures do not require reconstruction or new construction of the city. / OptiDrift
8

Koncentrace tuhé znečišťující látky uvnitř stáje velkochovu drůbeže v závislosti na stáří drůbeže

DVOŘÁK, David January 2018 (has links)
This thesis deals with the issue of air pollution, emission of solid substance in the large-scale poultry. Compares the level of surface contamination inside the breeding facility, depending on the age of the poultry. The measurements were carried out in accordance with the applicable methodology for the evaluation and the determination of the concentration of dust particles PM10 in the selected large-scale poultry. Measurement was carried out in a large-scale broiler Farma u lesa in Sudoměřice u Bechyně. The aim of this work was to obtain a measurement and then evaluate the data obtained. The measurements were carried out in two rounds to measure two size fractions of solid pollutants. The DUST TRAK 8530, borrowed by the faculty, was used to measure the solid dust particles in bulge. Further, the thesis also describes description and measurement methodology with this device.
9

ENVIRONMENTAL INTERNSHIP-ENVIRONMENTAL QUALITY MANAGEMENT, INC. TECHNICAL SERVICES DIVISION

Cook, Randal James 03 September 2004 (has links)
No description available.
10

Meteorologische Einflüsse auf die Konzentrationen feiner und grober atmosphärischer Aerosolpartikel in Deutschland

Engler, Christa 19 March 2014 (has links) (PDF)
Atmosphärische Aerosolpartikel können durch ein breites Spektrum an natürlichen oder anthropogenen Emissionen mit unterschiedlich hohen Konzentrationen in die Atmosphäre freigesetzt werden. Sie beeinflussen den Strahlungshaushalt und damit auch das Klima der Erde und können außerdem durch ihre Präsenz in der Atmosphäre Wechselwirkungen mit Mensch und Natur, also dem gesamten Ökosystem haben. Seit dem Jahr 2010 gelten in der EU Grenzwerte für die PM10 Tagesmittelkonzentration, die jedoch bereits wenige Monate nach Beginn der Gültigkeit an vielen Messstationen überschritten wurden. Das Ziel der vorliegenden Arbeit war eine objektive Bewertung der Herkunft und des Zustandes der an einem Messort ankommenden Luftmasse und der damit verbundenen Schadstoffniveaus. Im ersten Teil der Arbeit wurden PM10 Messdaten aus fünf Jahren in und um Leipzig sowie analog in fünf verschiedenen Regionen deutschlandweit in Bezug auf PM10 Grenzwertüberschreitungen untersucht. Es wurden Rückwärtstrajektorien für eine Clusteranalyse verwendet, mit der spezifische Wetterlagen unterschieden wurden und diesen dann die einzelnen Messtage mit den zugehörigen Schadstoffkonzentrationen zugeordnet wurden. Hierbei wurde deutlich, dass durch entsprechende meteorologische Bedingungen sowohl lokal als auch regional emittierte Schadstoffe in Bodennähe akkumulieren oder aber auch räumlich verteilt werden können. Außerdem wurde in dieser Arbeit eine Modellvalidierung vorgestellt. Es wurde das Modellsystem COSMO-MUSCAT/ext-M7 verwendet, dessen Ergebnisse mit Beobachtungsdaten verglichen wurden. Als erstes wurde die Beschreibung der meteorologischen Bedingungen, dann die räumliche Verteilung von PM10, die chemische Partikelzusammensetzung sowie physikalische Aerosolparameter wie Partikelanzahl, -volumen und -durchmesser verglichen. Die Ergebnisse deuten darauf hin, dass nach wie vor Probleme bei der Beschreibung der mikrophysikalischen Aerosoleigenschaften bestehen. Die Größenordnungen der verglichenen Parameter können vom Modell abgebildet werden, dennoch müssen Modellergebnisse nach wie vor mit Vorsicht interpretiert werden, insbesondere hinsichtlich von Prozessen, bei denen die Partikelanzahl eine Rolle spielen.

Page generated in 0.0373 seconds