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  • 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

Applications and evaluation of receptor modeling methods for source contribution of volatile organic compounds

Snorradottir, Thorunn. January 2006 (has links)
Thesis (Ph. D.)--University of Nevada, Reno, 2006. / "August, 2006." Includes bibliographical references (leaves xx-xx). Online version available on the World Wide Web.
2

Modelling atmospheric ozone concentration using machine learning algorithms

Al-Abri, Eman S. January 2016 (has links)
Air quality monitoring is one of several important tasks carried out in the area of environmental science and engineering. Accordingly, the development of air quality predictive models can be very useful as such models can provide early warnings of pollution levels increasing to unsatisfactory levels. The literature review conducted within the research context of this thesis revealed that only a limited number of widely used machine learning algorithms have been employed for the modelling of the concentrations of atmospheric gases such as ozone, nitrogen oxides etc. Despite this observation the research and technology area of machine learning has recently advanced significantly with the introduction of ensemble learning techniques, convolutional and deep neural networks etc. Given these observations the research presented in this thesis aims to investigate the effective use of ensemble learning algorithms with optimised algorithmic settings and the appropriate choice of base layer algorithms to create effective and efficient models for the prediction and forecasting of specifically, ground level ozone (O3). Three main research contributions have been made by this thesis in the application area of modelling O3 concentrations. As the first contribution, the performance of several ensemble learning (Homogeneous and Heterogonous) algorithms were investigated and compared with all popular and widely used single base learning algorithms. The results have showed impressive prediction performance improvement obtainable by using meta learning (Bagging, Stacking, and Voting) algorithms. The performances of the three investigated meta learning algorithms were similar in nature giving an average 0.91 correlation coefficient, in prediction accuracy. Thus as a second contribution, the effective use of feature selection and parameter based optimisation was carried out in conjunction with the application of Multilayer Perceptron, Support Vector Machines, Random Forest and Bagging based learning techniques providing significant improvements in prediction accuracy. The third contribution of research presented in this thesis includes the univariate and multivariate forecasting of ozone concentrations based of optimised Ensemble Learning algorithms. The results reported supersedes the accuracy levels reported in forecasting Ozone concentration variations based on widely used, single base learning algorithms. In summary the research conducted within this thesis bridges an existing research gap in big data analytics related to environment pollution modelling, prediction and forecasting where present research is largely limited to using standard learning algorithms such as Artificial Neural Networks and Support Vector Machines often available within popular commercial software packages.
3

Land use forecasting in regional air quality modeling

Song, Ji Hee, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.
4

Ozonentwicklung im polnisch-sächsischen Grenzraum: Ozonentwicklung im polnisch-sächsischen Grenzraum im Rahmen des Projektes KLAPS

Heidenreich, Majana, Riedel, Kathrin, Fischer, Stefanie, Bernhofer, Christian 06 May 2015 (has links)
Ein Teilziel des Projektes KLAPS ist eine auf die Projektregion ausgerichtete Analyse der Ozonbelastung in Abhängigkeit klimatischer Einflussfaktoren. Im vorliegenden Bericht werden die zeitlichen Verläufe der Vorläufersubstanzen und der Einfluss meteorologischer Bedingungen auf die Ozonkonzentration im 21. Jahrhundert untersucht. Die Ergebnisse verweisen auf einen möglichen Anstieg der Ozonkonzentration in den Sommermonaten der nächsten Jahrzehnte allein durch die Auswirkungen des Klimawandels. Entscheidend für die zukünftige Höhe der Ozonkonzentration ist allerdings die Entwicklung der Emissionen im Projektgebiet.

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