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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

Análise e propagação de incertezas associadas à Dispersão atmosférica dos gases da unidade snox®

MELO, Rony Glauco de 18 September 2015 (has links)
Submitted by Haroudo Xavier Filho (haroudo.xavierfo@ufpe.br) on 2016-07-01T12:40:07Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_RonyMelo_Versao_BC_2.pdf: 1810035 bytes, checksum: 3c75da73e467a1195a630f09d398de6a (MD5) / Made available in DSpace on 2016-07-01T12:40:07Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese_RonyMelo_Versao_BC_2.pdf: 1810035 bytes, checksum: 3c75da73e467a1195a630f09d398de6a (MD5) Previous issue date: 2015-09-18 / Anp/prh-28 / O aprimoramento de tecnologias que possam tornar o processo produtivo mais amigável a sociedade e ao meio ambiente é uma busca constante das grandes indústrias, seja por questões mercadológicas, seja por obrigações legais. A indústria do refino de petróleo, pela própria natureza composicional de sua matéria prima principal, produz efluentes com os mais diferentes riscos, os quais necessitam ser eliminados ou reduzidos a níveis aceitáveis. Inserido dentro deste contexto surge à unidade de abatimentos de emissões atmosféricas SNOX®, cujos objetivos visam o tratamento de efluentes e produção de H2SO4 agregando assim valor comercial ao processo, contudo esses mesmos efluentes conferem a possibilidade de sofrer diversos processos corrosivos e que pode acarretar vazamentos de seus gases, os quais são, em sua maioria, nocivos. O presente trabalho teve como objetivos a elaboração de uma simulação em modo estacionário, do processo SNOX® utilizando o software Hysys® a fim de calcular as concentrações dos diversos gases circulantes, e avaliar, de forma probabilística, a dispersão atmosférica (através do modelo SLAB) desses gases devido à presença de incertezas em diversas variáveis. Para a avaliação probabilística foi utilizada técnicas de Quasi-Monte Carlo (Latin Hypercube) para: definição das incertezas relevantes e hierarquização destas através de análise de sensibilidade por decomposição de variâncias; cálculo do tamanho ideal das amostras que representarão as incertezas, considerando um intervalo de confiança de 90%; e exibição dos resultados na forma de famílias de curvas de distribuição de probabilidade para obtenção probabilidades de certos efeitos adversos referentes aos gases presentes no processo SNOX®. Os resultados mostraram que, considerando as condições operacionais da unidade e o tipo de consequência abordado (intoxicação por gases): coeficiente de descarga, vazão de descarga, velocidade (intensidade) dos ventos e diâmetro do orifício são as variáveis que possuem relevância e as incertezas associadas a esses resultados se propagam até as concentrações finais obtidas pelo modelo SLAB, fazendo com que sua melhor representação seja na forma de curvas de distribuição de probabilidades cumulativas. / The improvement of technologies which can implement greater eco-socialfriendly production processes are a goal for the major industries, either by marketing issues or legal restrictions. The oil industry, by its compositional nature of its feedstock, produces effluents with several hazards which must be eliminated or reduced to acceptable levels. In this context, the SNOX® unit rises as answer to the reduction of the atmospheric emissions, aiming the effluent treatment and H2SO4 production, which increases the commercial value to the process, notwithstanding the fact of these emissions enable corrosive process that may lead to leakage of gases, which are usually harmful. The current work has as main objectives the development of a simulation at stationary-state of the SNOX® process by using the HYSYS® software in order calculate the concentration of released gases and probabilistically evaluate the atmospheric dispersion of these gases employing SLAB method. The Quasi-Monte Carlo (Latin Hypercube) was used for probabilistic estimation for: defining the relevant uncertainties as well its hierarchization through sensibility analysis by variance decomposition; calculation of the ideal size for the samples which will represent the uncertainty with a reliability of 90%; and finally for displaying the results as groups of probability distribution curves to obtain the probability of some adverse effects associated with the gases at the process. The results evidenced that considering the operational conditions and the studied kind of consequences (gas intoxication): discharge coefficient, discharge flow rate, wind velocity (intensity of the wind) and the diameter of the orifice were the variables of relevance and the associated uncertainties of the results propagate to the final concentrations obtained by the SLAB model. Hence the results must be suitably represented by cumulative probability distribution curves.
12

Light Management in Optoelectronic Devices with Disordered and Chaotic Structures

Khan, Yasser 07 1900 (has links)
With experimental realization, energy harvesting capabilities of chaotic microstructures were explored. Incident photons falling into chaotic trajectories resulted in energy buildup for certain frequencies. As a consequence, many fold enhancement in light trapping was observed. These ellipsoid like chaotic microstructures demonstrated 25% enhancement in light trapping at 450nm excitation and 15% enhancement at 550nm excitation. Optimization of these structures can drive novel chaos-assisted energy harvesting systems. In subsequent sections of the thesis, prospect of broadband light extraction from white light emitting diodes were investigated, which is an unchallenged but quintessential problem in solid-state lighting. Size dependent scattering allows microstructures to interact strongly with narrow-band light. If disorder is introduced in spread and sizes of microstructures, broadband light extraction is possible. A novel scheme with Voronoi tessellation to quantify disorder in physical systems was also introduced, and a link between voronoi disorder and state disorder of statistical mechanics was established. Overall, in this thesis some nascent concepts regarding disorder and chaos were investigated to efficiently manage electromagnetic waves in optoelectronic devices.
13

Quantifying Riverbed Sediment Using Recreational-Grade Side Scan Sonar

Hamill, Daniel 01 August 2017 (has links)
The size and organization of bed material, bed texture, is a fundamental attribute of channels and is one component of the physical habitat of aquatic ecosystems. Multiple discipline-specific definitions of texture exist and there is not a universally accepted metric(s) to quantify the spectrum of possible bed textures found in aquatic environments. Moreover, metrics to describe texture are strictly statistical. Recreational-grade side scan sonar systems now offer the possibility of imaging submerged riverbed sediment at resolutions potentially sufficient to identify subtle changes in bed texture with minimal cost,expertise in sonar, or logistical effort. However, inferring riverbed sediment from side scan sonar data is limited because recreational-grade systems were not designed for this purpose and methods to interpret the data have relied on manual and semi-automated routines. Visual interpretation of side scan sonar data is not practically applied to large volumes of data because it is labor intensive and lacks reproducibility. This thesis addresses current limitations associated with visual interpretation with two objectives: 1) objectively quantify side scan sonar imagery texture, and 2) develop an automated texture segmentation algorithm for broad-scale substrate characterization. To address objective 1), I used a time series of imagery collected along a 1.6 km reach of the Colorado River in Marble Canyon, AZ. A statistically based texture analysis was performed on georeferenced side scan sonar imagery to identify objective metrics that could be used to discriminate different sediment types. A Grey Level Co-occurrence Matrix based texture analysis was found to successfully discriminate the textures associated with different sediment types. Texture varies significantly at the scale of ≈ 9 m2 on side scan sonar imagery on a regular 25 cm grid. A minimum of three and maximum of five distinct textures could be observed directly from side scan sonar imagery. To address objective 2), linear least squares and a Gaussian mixture modeling approach were developed and tested. Both sediment classification methods were found to successfully classify heterogeneous riverbeds into homogeneous patches of sand, gravel, and boulders. Gaussian mixture models outperformed the least squares models because they classified gravel with the highest accuracies.Additionally, substrate maps derived from a Gaussian modeling approach were found to be able to better estimate reach averaged proportions of different sediments types when they were compared to similar maps derived from multibeam sonar.
14

Continuous Unbonded Post-Tensioned Members: Quantifying Strand Stress Increase

Six, Philip D. 01 May 2015 (has links)
Unbonded post-tensioning tendons are an efficient and cost effective method of reinforcing concrete floor slabs, slabs-on-grade, parking garages, and bridge structures. However, the behavior of these structures is not well understood. There is concern that due to the lack of a significant amount of reliable research data on specimens reinforced in this manner, the commonly used design methods tend to significantly under-predict the strength. Four large, scaled, floor slab sections were constructed and destructively tested with the intent of more accurately understanding the strength of specimens reinforced with this method. Four test specimens represent a significant percentage of the current body of reliable research in this field. In order to accurately predict the design strength of these members, it is necessary to predict the increase in the reinforcing strand stress when the member is loaded to a flexural failure. This increase in strand stress was measured on each of the four laboratory tests which were performed. This allowed the strength of these concrete members to be more accurately predicted, and it was observed that the current design methods are significantly under-predicting this increase in strand stress as well as the flexural capacity of the members. The behavior of the deflection of the slabs in relation to the applied load was also analyzed, as well as the cracking behaviors. The four test specimens were combined with the available body of research data to complete the largest known database of members reinforced in this manner.
15

2D PASS-CPMG: A New NMR Method for Quantifying Structure in Non-Crystalline Solids

Vickers, Samantha Grace 26 June 2009 (has links)
No description available.
16

Reproducing and Quantifying Spatial Flow Patterns of Ecological Importance with Two-Dimensional Hydraulic Models

Crowder, David Willis 20 November 2002 (has links)
Natural streams typically have highly complex flow patterns. Velocity gradients, circulation zones, transverse flows, and other flow patterns are created in the presence of topographic features (e.g. exposed boulders, bars). How flow complexity influences a stream's ecological health and morphological stability, as well as how flow complexity responds to changes in hydrologic conditions, is poorly understood. One-dimensional (1-D) hydraulic models and two-dimensional (2-D) models that do not explicitly incorporate meso-scale topographic features are not capable of adequately reproducing the flow patterns found in channels having complex topography. Moreover, point measurements of depth and velocity, which are used to describe hydraulic conditions in habitat suitability studies, cannot be used to characterize spatially varying flow patterns of biological importance. A general methodology for incorporating meso-scale topography into 2-D hydraulic models is presented. The method provides a means of adequately reproducing spatial flows of interest to riverine researchers. The method is developed using 2-D model simulations of a reach of the North Fork of the Feather River in California. Specifically, the site is modeled with and without bathymetry data on exposed boulders found within the site. Results show that the incorporation of boulder topography and an adequately refined mesh are necessary for reproducing velocity gradients, transverse flows, and other spatial flows. These simulations are also used to develop and evaluate three spatial hydraulic metrics designed to distinguish between locations having uniform and non-uniform flow conditions. The first two metrics describe local variations in energy/velocity gradients, while the third metric provides a measure of the flow complexity occurring within an arbitrary area. The metrics based on principles of fluid mechanics (kinetic energy, vorticity, and circulation) can be computed in the field or with 2-D hydraulic model results. These three metrics, used in conjunction with detailed 2-D hydraulic model results, provide engineers, biologist, and water resource managers a set of tools with which to evaluate the importance of flow complexity within rivers. A conceptual model describing how such a tool can be used to help design channels being restored, better evaluate stream habitat, and evaluate how hydrologic changes in a watershed impact hydraulic conditions and concomitant habitat conditions is provided. / Ph. D.
17

Quantifying synergy value in mergers and acquisitions

De Graaf, Albert 06 1900 (has links)
Mergers and acquisitions have been demonstrated to create synergies, but not in all cases. Current research reveals that where synergies exist, these seem to accrue to the shareholders of the selling companies. Given the limitations of our qualitative research design, we find that it is important to quantify synergy before the acquisition, preferably by applying certain best practices. In an attempt to enhance understanding of the phenomenon, we find that several types of synergy exist and that their origins include efficiencies, such as economies of scale and economies in innovative activity. We further find that the bid price is an important indicator of success and that its maximum should not exceed the intrinsic value of the target, plus the value of synergies between the bidder and target. We further find that best practices exist in quantifying cost and revenue synergies and describe these separately per origin. / Management Accounting / M.Com. (Accounting)
18

Avaliação comparativa de diferentes métodos de quantificação de formas teciduais de Trypanosoma cruzi na infecção experimental / Comparative evaluation of differents methodologies in tecidual types quantification of trypanosoma cruzi

Augusto, Mariana Bryan 02 August 2010 (has links)
Completando 100 anos da descoberta da molestia, a Doenca de Chagas, causada pelo agente etiologico Trypanosoma cruzi, ainda e considerada nas Americas Central e do Sul um problema de saude publica, atingindo mais de 8 milhoes de individuos. Sua transmissao ocorre de distintas maneiras, como por vetores, transfusao sanguinea, transplante de orgaos, acidentes em laboratorios, via oral. O parasita e conhecido por sua heterogeneidade no genotipo e fenotipo, baseado em mutacoes cumulativas em diferentes sub-populacoes do parasita. A cepa CL Brener e uma cepa padrao para pesquisa com diversas peculiaridades interessantes como baixa infectividade em animais, resposta aos tratamentos existentes e seus marcadores geneticos serem estaveis. O clone CL B5 de T. cruzi e originado a partir da cepa CL Brener modificada geneticamente. A cepa possui um gene reporter, o LacZ de Escherichia coli que sintetiza uma enzima, a À-galactose que pode catalisar uma reacao colorimetrica com o substrato vermelho de clorofenol À-galactopiranosideo (CPRG). A atividade enzimatica e diretamente proporcional ao numero de parasita. No presente trabalho propomos a introducao de uma tecnica colorimetrica para caracterizacao de parametros para quantificacao do parasitismo tecidual e comparacao com a tecnica histologica e Real Time-PCR. Camundongos Balb/C machos foram divididos em grupos controle (nao infectado) e experimental variando a via de inoculacao, a saber, intraperitoneal (IP), subcutanea (SC) e oral (OR). As curvas parasitemicas foram realizadas por meio da coleta de sangue da cauda do animal. Apos morte dos mesmos, foram estudados os tecidos cardiaco, hepatico, esplenico, enterico e muscular (musculo esqueletico). Os orgaos foram retirados, divididos em tres porcoes equitativas para analise histologica, enzimatica e molecular. Na atividade enzimatica, comparando os tecidos em suas vias de inoculacao, o figado apresentou resultado significativo no grupo inoculado via IP. Tecido cardiaco apresentou diferenca estatistica (P<0,05) entre as vias de inoculacao OR e SC, apresentando maior atividade enzimatica na primeira, o que esta relacionado a uma maior quantidade de parasita tecidual. Nos cortes histologicos o grupo SC mostrou-se mais infectado com grande numero de ninhos de forma amastigota em praticamente todos os tecidos, enquanto nos demais grupos foram observados ninhos de amastigota em sua maioria no coracao e viii musculo esqueletico. A presenca do parasita nos demais tecidos foi confirmada pela eletroforese em gel de agarose 1,5% apos tecnica de PCR convencional. A Real Time-PCR nao se mostrou satisfatoria no trabalho devido a dificuldade na sua padronizacao. Concluindo, a metodologia enzimatica se mostrou favoravel e adequada na quantificacao parasitaria tecidual, podendo ser aperfeicoada para corroborar sua eficacia. / One hundred years after the discovery of Chagas Disease, an illness caused by blood born protozoan Trypanosoma cruzi, is still consider a public health problem. It is a major cause of morbidity and mortality in Central and South Americas where more than 8 million individuals are already infected. This illness can be contracted by different forms as vector transmission, blood transfusion, tissue transplant, laboratory accidents and oral route. The parasite has a heterogeneous genotype and phenotype due to accumulating mutation in their sub-populations. CL Brener is considered as a pattern strain due to some intrinsic characteristics as low infectivity, good response to therapy drugs and a stable genetic heritage. The CL B5 clone of T. cruzi was originated by a genetic modification of the CL Brener strain which has a reporter gene LacZ of Escherichia coli, which induces the syntesis of â-galactosidase which is able to catalyze a colorimetric reaction using the substrat Chlorophenol red-â-D-galactopyranoside (CPRG). The enzymatic activity is directly related with the number of the parasites. In this study we proposed a new colorimetric assay to quantify T. cruzi load in different animal tissues by comparing with other methodologies such histological and molecular assay (Real Time-PCR). Male Balb/C mice were separated into control and experimental groups according to the route of infection (IP-intraperitoneal, SC-subcutaneous, OR-oral). Parasitemic curves were made by collecting blood samples from the tail of experimental animals. Fifteen days after, animals were euthanized and their tissues removed (heart, liver, spleen, intestine and skeletal muscles) and divided in three portions for the colorimetric analyses, histopathology and molecular assay. The enzymatic activity was performed comparing the number of parasites in different tissues according to the route of infection. Comparing them, it was observed that heart and liver displayed the highest number of parasites as compared with the other studied tissues. In the liver, IP route triggered the highest number of parasites while in the heart OR and SC routes displayed enhanced parasites. The histopathology analysis revealed that SC group presented the highest number of amastigote nests. For IP and OR groups, nests were mostly observed in heart and skeletal muscles. T. cruzi DNA were detected using electrophoreses 1,5 % agarose gel after conventional PCR technique, displaying characteristic bands of DNA. The Real Time-PCR was not a satisfactory x assay for this study due to difficulties on its patronization. To conclude, the enzymatic methodology was advantageous and appropriated on quantifying tissue parasites. Some further experiments will be needed to improve methodology and its efficacy.
19

Quantifying Risk Management Process In A Software Organization

Yakin, Cenkler 01 April 2006 (has links) (PDF)
This study presents a quantifying risk management process and its application on a software organization in terms of risk items mitigated, exposures covered, costs, and expected exposures covered. Risk management is defined as setting forth a discipline and environment of proactive decisions and actions to assess continuously what can go wrong (risks), to determine what risks are important to deal with, and to implement strategies to deal with those risks. Risk management can be applied in all of the business areas. In the literature, there are sources for risk management. Some of them are qualitative, and some of them are quantitative. However, there is no much source about the application study of a quantifying risk management process on a software organization. In order to obtain insight about this issue, this study presents a quantifying risk management system to the literature and also compares the quantifying risk management policies on the data set of a software organization by finding out and analyzing their performance with respect to designated decision parameters and preference profiles for risk items mitigated, exposures covered, costs, and expected exposures covered. At the end of this study, suitable quantifying risk management policies for each profile are recommended by considering the analysis of the data set as base.
20

Quantifying synergy value in mergers and acquisitions

De Graaf, Albert 06 1900 (has links)
Mergers and acquisitions have been demonstrated to create synergies, but not in all cases. Current research reveals that where synergies exist, these seem to accrue to the shareholders of the selling companies. Given the limitations of our qualitative research design, we find that it is important to quantify synergy before the acquisition, preferably by applying certain best practices. In an attempt to enhance understanding of the phenomenon, we find that several types of synergy exist and that their origins include efficiencies, such as economies of scale and economies in innovative activity. We further find that the bid price is an important indicator of success and that its maximum should not exceed the intrinsic value of the target, plus the value of synergies between the bidder and target. We further find that best practices exist in quantifying cost and revenue synergies and describe these separately per origin. / Management Accounting / M.Com. (Accounting)

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