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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.
11

Back-calculating emission rates for ammonia and particulate matter from area sources using dispersion modeling

Price, Jacqueline Elaine 15 November 2004 (has links)
Engineering directly impacts current and future regulatory policy decisions. The foundation of air pollution control and air pollution dispersion modeling lies in the math, chemistry, and physics of the environment. Therefore, regulatory decision making must rely upon sound science and engineering as the core of appropriate policy making (objective analysis in lieu of subjective opinion). This research evaluated particulate matter and ammonia concentration data as well as two modeling methods, a backward Lagrangian stochastic model and a Gaussian plume dispersion model. This analysis assessed the uncertainty surrounding each sampling procedure in order to gain a better understanding of the uncertainty in the final emission rate calculation (a basis for federal regulation), and it assessed the differences between emission rates generated using two different dispersion models. First, this research evaluated the uncertainty encompassing the gravimetric sampling of particulate matter and the passive ammonia sampling technique at an animal feeding operation. Future research will be to further determine the wind velocity profile as well as determining the vertical temperature gradient during the modeling time period. This information will help quantify the uncertainty of the meteorological model inputs into the dispersion model, which will aid in understanding the propagated uncertainty in the dispersion modeling outputs. Next, an evaluation of the emission rates generated by both the Industrial Source Complex (Gaussian) model and the WindTrax (backward-Lagrangian stochastic) model revealed that the calculated emission concentrations from each model using the average emission rate generated by the model are extremely close in value. However, the average emission rates calculated by the models vary by a factor of 10. This is extremely troubling. In conclusion, current and future sources are regulated based on emission rate data from previous time periods. Emission factors are published for regulation of various sources, and these emission factors are derived based upon back-calculated model emission rates and site management practices. Thus, this factor of 10 ratio in the emission rates could prove troubling in terms of regulation if the model that the emission rate is back-calculated from is not used as the model to predict a future downwind pollutant concentration.
12

Desenvolvimento e aplicação do pacote computacional LUMPAC

DUTRA, José Diogo de Lisboa 26 January 2017 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-08-01T13:42:24Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) JDiogo_Tese Final_Quimica.pdf: 8861608 bytes, checksum: b9ce8a33624820a531c0a5c298600d94 (MD5) / Made available in DSpace on 2017-08-01T13:42:24Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) JDiogo_Tese Final_Quimica.pdf: 8861608 bytes, checksum: b9ce8a33624820a531c0a5c298600d94 (MD5) Previous issue date: 2017-01-26 / CNPQ / Metodologias te´oricas s˜ao ´uteis para complementar investigac¸˜oes experimentais e guiar novos experimentos envolvendo compostos luminescentes de lantan´ıdeos. A ausˆencia de uma ferramenta computacional contendo tais m´etodos motivou o desenvolvimento do LUMPAC. Se por um lado o LUMPAC difundiu o uso dessas metodologias, por outro as suas limitac¸˜oes tamb´em foram evidenciadas. Nesse sentido, pˆode-se conhecer melhor quais m´etodos merecem uma atenc¸˜ao especial, a saber: c´alculo dos parˆametros de intensidade (Ωλ), c´alculo da energia dos estados excitados dos ligantes e c´alculo da taxa de emiss˜ao n˜ao-radiativa (Anrad). O objetivo geral do presente trabalho de doutoramento consiste em corrigir algumas dessas limitac¸˜oes. Quantoaoc´alculodosΩλ,conseguimosatenuaroproblemacomumanovaformadeajustedos fatores de carga e das polarizabilidades atrav´es de um procedimento que foi denominado de Modelo da UnicidadeQDC, o qual faz uso de um conjunto bastante reduzido de parˆametros (Q,D eC). A importˆancia do ajusteQDC ´e que todas as quantidades derivadas se tornam tamb´em ´unicas para uma dada geometria do complexo, incluindo um esquema proposto de partic¸˜ao qu´ımico da taxa de emiss˜ao radiativa (Arad) em termos dos efeitos dos ligantes. Para demonstrar uma das poss´ıveis aplicac¸˜oes dessa partic¸˜ao, foi considerado o caso de complexos tern´arios de Eu3+ de ligantes n˜ao-iˆonicos repetidos e com os ligantes betadicetonatos DBM, TTA e BTFA. A partic¸˜ao ordenou perfeitamente a combinac¸˜ao n˜ao ´obvia de pares de ligantes n˜ao-iˆonicos que levam aos compostos misturados com os maiores valores deAexp rad. Quanto ao c´alculo dos estados excitados dos ligantes, ´e proposta uma parametrizac¸˜ao do m´etodo CIS baseadonaaproximac¸˜aoNDDO,exclusivamenteparasistemaslantan´ıdicos. Al´emdisso,realizamosumestudoavaliativodemetodologiasTDDFTaplicadasaoc´alculodeestadosexcitados de ligantes em complexos de lantan´ıdeos. Dentre os funcionais e func¸˜oes de base avaliados, a combinac¸˜ao LC-ωPBE/6-31G(d) foi aquela que forneceu as energias tripleto mais concordantes com os dados obtidos na literatura, sendo o erro m´edio absoluto correspondente em torno de 1600 cm−1. Atrav´es da parametrizac¸˜ao do modelo NDDO-CIS implementado no programa ORCA foi poss´ıvel obter um modelo semiemp´ırico para o c´alculo da energia tripleto de complexosdelantan´ıdeocom qualidade bem superiora da melhormetodologiaTDDFT avaliada. / Theoretical methodologies are useful to complement experimental investigations, and to guide new experiments involving luminescent lanthanide compounds. The lack of a software containing these methods motivated us to the development of the user friendly software package LUMPAC. And indeed, LUMPAC is slowly popularising the use of these theoretical methodologies - methodologies that are being put to more frequent tests, and are, consequently, slowly revealing their limitations. In this sense, we identified which aspects of the methods would deserve a more special attention, namely: intensity parameters calculations (Ωλ), calculation of the excited state energies of the ligands, and the calculation of the non-radiative decay rate (Anrad). The overall objective of this doctoral work is to correct some of these limitations as wellastoadvancenewdevelopments. RegardingtheΩλ calculation,wemitigatedthisproblem with a new way to adjust the charge factors and polarizabilities through a procedure we called theQDC Uniqueness Model, which makes use of a fairly small set of adjustaeble parameters (Q,D, andC). The importance of theQDC adjustment is that all derived quantities become also unique for a given complex geometry, including the chemical partition of the radiative emission rate (Arad) in terms of the effects of the ligands, which is being advanced here. To demonstrate one of the possible applications of this chemical partition, we address the case of repeating non-ionic ligand ternary complexes of europium(III) with DBM, TTA, and BTFA. The chemical partition perfectly ordered the non-obvious combination of pairs of non-ionic ligands that led to the mixed ligand compounds with the highest values ofAexp rad . Regarding the calculation of the excited states of the ligands, a new parametrization of the CIS method based on the NDDO approximation is being proposed, exclusively for lanthanide complexes. In addition, we carried out a study to evaluate some TDDFT methodologies for the calculation of excited states of ligands in lanthanide complexes. Among the functionals and basis sets evaluated, the combination LC-ωPBE/6-31G(d) was the one that led to the lowest UME (unsigned mean error), of around 1600 cm−1, for the triplet energies in comparison with data from the literature. The parametrization of the NDDO-CIS model implemented into ORCA provided a semiempirical method for the triplet energy calculation of lanthanide complexes with better predictionpower thanthebestassessed TDDFT method.
13

水田から発生するメタンの主要な炭素源の確定

木村, 眞人, 渡辺, 彰 03 1900 (has links)
科学研究費補助金 研究種目:一般研究(B) 課題番号:05454067 研究代表者:木村 真人 研究期間:1993-1994年度

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