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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.
91

Uranium Mining Industry : -A valuation of uranium mining companies

Östlund, Jacob, Kierkegaard, Kristian January 2007 (has links)
<p>Background:</p><p>Over the last three years uranium prices have soard from US $14 per pound (lb) to the current price of US $120/lb and this rapid incline of the commodity have created a boom within the uranium prospecting and min-ing industry. There are currently 435 nuclear reactors all over the world and these reactors demand 180 millions of pounds of uranium each year to run at full production. Currently the uranium mining industry only sup-plies 110 million pounds of the demanded quantity. The remaining 70 mil-lion pounds are coming from secondary sources such as decommissioned nuclear warheads and other sources. Market estimations say that the sec-ondary sources will only cover the shortage up until around 2012 then primary sources have to supply almost the whole quantity demanded. These factors imply that some sort of analysis model for uranium mining companies would be needed.</p><p>Purpose:</p><p>The purpose of this report is to valuate three companies within the ura-nium industry and to establish if the current market value is coherent with the fundamental value of these companies. The authors will propose a valuation model that could be used when valuating companies within the uranium industry.</p><p>Method:</p><p>A qualitative method has been used in order to value three companies within the uranium mining business that are fairly large players on the market. The valuation of these companies is based upon a discounted cash flow analysis, a relative PV valuation and relative valuation. The compa-nies included in the report are corporations that are quoted at Toronto Stock Exchange and they have started mining uranium. Data have been collected through annual reports and the companies Internet pages. Other secondary information such as valuation theories has been collected from academic search engines and books on the subjects.</p><p>Conclusions:</p><p>The current market values of uranium mining companies are not coherent with the actual fundamental values according to the authors. Both funda-mental and a comparative approach could be used when valuing these companies and the most important part in the valuation is to try and fore-cast the commodity price and then to estimate the companies possible mining reserve/extractable resources.</p>
92

Adaptive constraint solving for information flow analysis

Dash, Santanu Kumar January 2015 (has links)
In program analysis, unknown properties for terms are typically represented symbolically as variables. Bound constraints on these variables can then specify multiple optimisation goals for computer programs and nd application in areas such as type theory, security, alias analysis and resource reasoning. Resolution of bound constraints is a problem steeped in graph theory; interdependencies between the variables is represented as a constraint graph. Additionally, constants are introduced into the system as concrete bounds over these variables and constants themselves are ordered over a lattice which is, once again, represented as a graph. Despite graph algorithms being central to bound constraint solving, most approaches to program optimisation that use bound constraint solving have treated their graph theoretic foundations as a black box. Little has been done to investigate the computational costs or design e cient graph algorithms for constraint resolution. Emerging examples of these lattices and bound constraint graphs, particularly from the domain of language-based security, are showing that these graphs and lattices are structurally diverse and could be arbitrarily large. Therefore, there is a pressing need to investigate the graph theoretic foundations of bound constraint solving. In this thesis, we investigate the computational costs of bound constraint solving from a graph theoretic perspective for Information Flow Analysis (IFA); IFA is a sub- eld of language-based security which veri es whether con dentiality and integrity of classified information is preserved as it is manipulated by a program. We present a novel framework based on graph decomposition for solving the (atomic) bound constraint problem for IFA. Our approach enables us to abstract away from connections between individual vertices to those between sets of vertices in both the constraint graph and an accompanying security lattice which defines ordering over constants. Thereby, we are able to achieve significant speedups compared to state-of-the-art graph algorithms applied to bound constraint solving. More importantly, our algorithms are highly adaptive in nature and seamlessly adapt to the structure of the constraint graph and the lattice. The computational costs of our approach is a function of the latent scope of decomposition in the constraint graph and the lattice; therefore, we enjoy the fastest runtime for every point in the structure-spectrum of these graphs and lattices. While the techniques in this dissertation are developed with IFA in mind, they can be extended to other application of the bound constraints problem, such as type inference and program analysis frameworks which use annotated type systems, where constants are ordered over a lattice.
93

Développement de systèmes d'analyse en flux imprimés en 3D pour le dosage de Pb, Cd et Hg dans les eaux / Development of 3D printed flow analysis systems for the determination of lead, cadmium, and mercury in water

Mattio, Elodie 16 November 2018 (has links)
La quantification des métaux dans les milieux aquatiques est un enjeu majeur, au vu de leur toxicité élevée et de leurs nombreuses sources d’émission dans l’environnement. Dans cette optique, le développement de systèmes d’analyse en ligne portables et à bas coût va permettre de réaliser des contrôles répétés et automatisés sur site. Trois métaux ont été ciblés dans cette étude : le plomb, le cadmium et le mercure. Pour développer ces systèmes, l’impression 3D a été utilisée pour réduire les coûts de fabrication et permettre la conception de modules sur mesure. Trois systèmes ont été développés, selon la méthodologie suivante : dans un premier temps, l’échantillon va être photo-oxydé pour extraire les métaux de la matrice organique et minérale, puis les métaux ciblés vont être ensuite préconcentrés sur phase solide, élués et détectés en spectroscopie UV-Visible ou en fluorescence. Les choix de la phase solide, de l’éluant et du réactif de détection vont ainsi être déterminants pour la caractérisation sélective et sensible de chaque métal. Un premier système pour l'analyse du plomb a été développé, et se compose de trois modules imprimés en 3D, accueillant une colonne de résine, un mélangeur, et une cellule de détection optique. Un second système, sous la forme d’un lab-on-valve, permet la quantification du plomb et du cadmium. Enfin le troisième système, portant sur le mercure, intègre une pièce imprimée en 3D dont la surface a été greffée avec une molécule (dithizone carboxylate) permettant l'extraction sélective du mercure du milieu. Ces systèmes conduisent ainsi à de nouvelles perspectives pour le développement de systèmes en flux plus complexes imprimés en 3D. / Metals determination in aqueous samples is a major challenge nowadays, in the light of their high toxicity and their numerous emission sources into the environment. In this context, the development of on-line and low-cost analytical systems allows to carry out automated on-site measurements. Three metals (lead, cadmium and mercury) have been targeted in this study. 3D printing has been used in this study to reduce fabrication costs and to allow a tailor-made conception of the units. The developed flow systems in this study are based on the same analytical methodology: first, the sample is photo-oxidized to extract targeted metals from organic and mineral matrix of the sample. Then, metals are preconcentrated on a solid phase, then eluted and detected by UV-Visible or fluorescence spectroscopy. The choices of preconcentration solid phases, eluents, and detection reagents are decisive for the selective and sensitive characterisation of each metal. The first developed system concerns lead analysis, and consists of three 3D printed units, which contain a resin column, a mixing coil, and a spectroscopic flow-cell. The second system for lead and cadmium determination contains a 3D printed lab-on-valve with eight ports, two resin columns, and a mixing coil with baffles. Finally, the third system includes a 3D printed unit whose surface has been modified by grafting a molecule with high affinity for mercury (dithizone carboxylate). This 3D printed unit provides a selective extraction of mercury after modification of its surface. The systems thus developed allow to explore the possibilities of 3D printing for the development of more complex flow systems.
94

Análise econômica da pequena mineração aplicando o conceito de reserva mínima. / Economic analysis of small-scale mine using the minimum mineral reserves concept.

Marin, Tatiane 05 August 2015 (has links)
Estima-se que cerca de 16 milhões de mineradores artesanais produzem entre 380 e 450 t de ouro por ano à escala global. Entretanto esta atividade ainda é negligenciada atores sociais e políticos internacionalmente. A equipe do NAP.Mineração vêm desenvolvendo técnicas e conceitos para transformar a mineração artesanal em uma pequena mineração responsável. Dentro destas iniciativas, foi desenvolvido o conceito de reserva mínima e replicação para adequar a pesquisa mineral à realidade da pequena mineral. A ideia central é minimizar o tempo e os recursos financeiros despendidos em pesquisa mineral, minimizando a reserva à apenas o estritamente necessário para o retorno financeiro do investimento inicial. Neste trabalho foi desenvolvido uma metodologia de análise econômica para a pequena mineração utilizando o conceito de reserva mínima, com diferentes estratégias de replicação da pesquisa mineral. A metodologia foi aplicada em um estudo de caso, uma pequena mina de ouro no Equador. Foi realizado também uma análise estocástica de sensibilidade à variação futuro do ouro. Os resultados mostram que a abordagem de reserva mínima é sempre mais vantajosa do ponto de vista econômico. Ao final é discutido o perfil de investidores para a pequena mineração. / It is estimated that about 16 million artisanal miners produce on a global scale between 380 and 450 t of gold per year. However, this activity is still neglected social and political actors internationally. The NAP.Mineração team have developed techniques and concepts to transform artisanal mining in a small mining responsibility. Within these initiatives, it developed the concept of minimum reserves and replication to suit mining research to the reality of small mineral. The central idea is to minimize the time and financial resources spent on mineral exploration, minimizing the reservation to only what is necessary to the financial return of the initial investment. This work developed a methodology of economic analysis for small-scale mining using the concept of minimum reserve with different replication strategies for mineral exploration. The methodology was applied in a case study, a small gold mine in Ecuador. It was also made a stochastic analysis future sensitivity variation of gold. The results show that the minimum booking approach is always more advantageous from an economic point of view. At the end it is discussed the profile for investor in the small-scale mining.
95

Material flow analysis and CO2 footprint in lumber from managed Brazilian Amazon rainforests. / Análise de fluxo de massa e pegada de CO2 em madeira serrada de florestas manejadas na Amazônia brasileira.

Numazawa, Camila Thiemy Dias 29 October 2018 (has links)
Using wood produced under forest management in the Amazon has been proposed as a way of preserving the ecosystem, generating jobs and to aid in climate change mitigation by using wood products as carbon stock and through CO2 uptake from the atmosphere during forest regrowth. However, the scarcity of research based on primary data of Amazonian lumber incorporated into construction can unknowingly lead to incorrect forest management and consequently forest destruction. Besides, it is necessary to verify the real environmental impacts. Two approaches were applied in this research to evaluate the wood product chain: material flow analysis and CO2 footprint calculation of managed Amazonian lumber. The research quantified the resource efficiency and CO2 footprint based on residue generation during the raw extraction in 5 forest plots in State of Pará, followed by the lumber production and the end-of-life phases, giving the CO2 balance between the emissions from residue decomposition and the CO2 uptake during forest regrowth, disregarding the energy consumption. Results indicated that the large quantities of logging residues are the main source of CO2 emissions in the material flow from selective logging, ranging from 9% to 36% of the initial forest biomass, while timber logs represented between 4% and 11%. Logging residues ranged from 2.9 t t-1 to 3.1 t t-1 per tonne of log. Combined with an average sawmill lumber yield of 54%, wastage rate values increased to between 5.7 t t-1 and 6.6 t t-1, resulting in a CO2 footprint of managed Amazonian lumber ranging between -6.6 tCO2 t-1 for reduced impact logging as carbon stock, to emissions of 6.1 tCO2 t-1 from cradle-to-gate for conventional logging. From cradle-to-grave the total CO2 footprint of lumber is estimated to range from neutral to 7.5 tCO2 t-1. Resource efficiency ranged from 13% to 15%. In this study, only the forest under reduced impact logging was able to fully recover its initial aboveground biomass, showing that in most cases regulations in the New Forest Code for Amazon forest management may not ensure sustainable logging, leading to forest destruction. Policies need to be improved and integrated with results from empirical research based on primary data to achieve sustainable exploitation of the Amazon forest. / O processo seletivo de utilização da madeira de manejo florestal na Amazônia tem sido proposto como forma de conservação e preservação do ecossistema, associada a geração de empregos e à mitigação de mudanças climáticas, pelo estoque de carbono dada a absorção de CO2 da atmosfera durante o crescimento da floresta. No entanto, a limitação de pesquisas baseadas em dados primários sobre madeiras amazônicas incorporadas na construção civil pode levar, inconscientemente, ao manejo florestal incorreto e, consequentemente, à destruição da floresta no contexto original e de reais impactos ambientais provocadas por ações inadequadas. Duas abordagens foram aplicadas nesta pesquisa para avaliar a cadeia de produtos de madeira: análise de fluxo de material e cálculo da pegada de CO2 da madeira manejada na Amazônia. A pesquisa analisou a eficiência dos recursos e a pegada de CO2 com base na geração de resíduos durante a extração em 5 florestas no Estado do Pará, produção madeireira e o fim de vida, proporcionando o balanço de CO2 entre as emissões da decomposição de resíduos e a absorção do CO2 durante a recomposição florestal, desconsiderando a energia consumida. Os resultados indicaram que o expressivo volume de resíduos florestais é a principal fonte de emissões de CO2 no fluxo de material proveniente da extração seletiva, variando de 9% a 36% da biomassa florestal inicial, enquanto os troncos de madeira representam entre 4% e 11%. Os resíduos de exploração florestal variaram de 2,9 a 3,1 t de resíduos por tonelada de tora. Combinado com um rendimento médio de madeira de serraria de 54%, os valores da taxa de desperdício aumentaram para entre 5,7 t e 6,6 t de resíduos por tonelada de tora e madeira serrada, resultando em uma pegada de CO2 variando entre -6,6 tCO2 t-1 (exploração de impacto reduzido) considerado estoque de carbono e as emissões de 6,1 tCO2 t-1 do berço à porta. No final da vida útil, estima-se que a pegada total de CO2 da madeira entre o berço e o túmulo é de neutra (exploração de impacto reduzido) a 7,5 tCO2 t-1, com uma eficiência de recursos variando de 13% a 15%. Neste estudo, apenas a floresta sob prática de extração de impacto reduzido foi capaz de recuperar totalmente sua biomassa inicial acima do solo, mostrando que as regulamentações do Novo Código Florestal para o manejo da florestal amazônica pode não garantir a sustentabilidade de uso do recurso florestal para aquela exploração que não esteja alicerçada dentro desse contexto de conservação da floresta original. As políticas precisam ser melhoradas, integradas e dinâmicas com base em resultados derivados de pesquisas empíricas baseadas em dados primários garantindo a exploração sustentável na Amazônia.
96

Sistemas microfluídicos amperométricos utilizando enzimas imobilizadas / Amperometric microfluidic systems using immobilized enzymes

Ferreira, Luís Marcos Cerdeira 05 May 2011 (has links)
Este trabalho descreve o desenvolvimento de um sistema microfluídico, contendo, como componente principal, um reator enzimático constituído de um microcanal fabricado em substrato de poli(metacrilato de metila) e um sistema amperométrico como detector. Para a construção de microcanais foi utilizando equipamento de usinagem a laser de CO2 para escavar os microcanais, que a seguir foram selados termicamente. A superfície interna desse microcanal foi submetida à modificação química com poli(etilenoimina), que se mostrou eficiente para posterior imobilização da enzima glicose oxidase, utilizando glutaraldeído como agente de ligação covalente cruzada, gerando assim um microrreator para determinação amperométrica de glicose. O peróxido de hidrogênio gerado na reação enzimática foi detectado em uma célula eletroquímica em fluxo, localizada externamente ao reator, com eletrodo de platina como eletrodo de trabalho. Uma bomba peristáltica programável foi empregada para promover a injeção de amostra, utilizando tubulação de pequeno diâmetro (0,3 mm), permitindo alcançar reprodutibilidade para a injeção de pequenos volumes, tipicamente da ordem de 5 microlitros de solução. O sistema proposto foi utilizado para a determinação amperométrica diferencial de glicose presente em amostras de refrigerantes, apresentando boa repetibilidade (DPR = 1,72%, n = 50), limite de detecção apreciável (1,40 x10-6 mol L-1), elevada frequência de amostragem (345 amostras h-1) e relativa estabilidade a longo prazo (420 determinações em mais de 20 dias com perda de atividade menor que 50%). As análises realizadas com o sistema proposto neste estudo levaram a resultados concordantes com os obtidos pelo método espectrofotométrico clássico, utilizado para análise de glicose em fluídos biológicos. / This work describes the development of a microfluidic system having as a main component an enzymatic reactor constituted by a microchannel assembled in poly(methyl methacrylate) substrate, connected to an amperometric detector. To manufacture the microchannels, a CO2 laser ablation machine was utilized to engrave the channels, which in sequence were thermally sealed. The internal surfaces of the microchannels were chemically modified with poly(ethyleneimine) which showed good effectiveness for the immobilization of glucose oxidase enzymes using glutaraldehyde as crosslinking agent, producing in this way a microreactor effective for the amperometric detection of glucose. The hydrogen peroxide generated in the enzymatic reaction was detected in the electrochemical flow cell, localized outside of the reactor, using platinum as the working electrode. A programmable peristaltic pump was utilized to inject the samples, utilizing tubes with small diameter (0.3 mm), allowing attain reproducibility even for injections of small volumes, in the order of 5 microliters of solution. The proposed system was applied for differential amperometric determination of glucose content in soft drinks, showing good repeatability (DPR = 1.72%, n = 50) low detection limit (1,40 x10-6 mol L-1), high sample frequency (345 samples h-1) and relatively good stability for long term (420 determinations along more than 20 days, with a decrease of activity lower than 50%). The analysis performed with the system proposed in this study lead to results which agree with those obtained by the classical spectrophotometric method, utilized to analyze glucose in biological fluids.
97

Emissão de CO2 da madeira serrada da Amazônia: o caso da exploração convencional. / CO2 of Amazon lumber: the case of conventional logging.

Campos, Érica Ferraz de 24 May 2012 (has links)
Informações ambientais de materiais e produtos são essenciais para a gestão de sustentabilidade no setor de construção. Em função das mudanças climáticas, o fator de emissão de dióxido de carbono (CO2) de produtos torna-se relevante para inventariar projetos e edificações, e pautar a decisão de profissionais e consumidores. Com base na metodologia de Análise de Fluxo do Material, a presente pesquisa objetivou quantificar o fator de emissão de CO2 da madeira serrada da Amazônia originária de exploração convencional. O recorte abrangeu a extração de toras da floresta, transporte de toras até serraria, processamento primário e transporte de madeira serrada ao mercado consumidor. Foram consideradas para o cálculo as emissões advindas de resíduos de biomassa e consumo de energia fóssil. Os resultados são apresentados em faixas de valores mínimos a máximos, para cada etapa produtiva, com o objetivo de incorporar incertezas e variações relativas às características do ambiente florestal e procedimentos da atividade madeireira. A quantificação foi principalmente baseada em dados de literatura; entrevistas e questionários com madeireiras da região foram utilizados para determinar o consumo de energia no processo. Entre 200 t/ha e 425 t/ha de biomassa seca acima do solo compõem a floresta Amazônica, de acordo com as características regionais. Essa biomassa estoca de 98 tC/ha a 208 tC/ha. Na exploração convencional são extraídas de 3 a 9 árvores por hectare, estimadas entre 4% e 14% da biomassa. Durante a extração, de 7% a 33% da biomassa florestal é danificada para abertura de trilhas, derrubada de árvores comerciais e arraste de toras. A biomassa destruída na extração é geralmente abandonada na floresta, onde se decompõe, gerando emissões. Nas serrarias, devido ao baixo aproveitamento, pelo menos 54% da biomassa das toras é transformada em resíduos, que são queimados ou degradam, outra fonte de CO2. Somando floresta e serraria, são produzidos de 5,0 t/t a 8,5 t/t na relação entre resíduos e madeira serrada. As emissões relativas aos resíduos, por unidade de tora processada, são estimados de 3,4 tCO2/t a 9,7 tCO2/t. As emissões por consumo de energia para extração, transporte de toras e processamento contribuem com 0,02 tCO2/t a 0,12 tCO2/t de tora processada. Ao final do processo produtivo, estimou-se a faixa de variação das emissões de 7,5 tCO2/t a 28,4 tCO2/t de madeira serrada, equivalentes a 5,2 tCO2/m³ e 19,6 tCO2/m³. Outra etapa considerada foi o transporte do produto entre serraria e mercado consumidor, que incrementa em 0,03 tCO2/t a 0,12 tCO2/t de madeira serrada, se admitidos 1.956 km, estimativa de distância média percorrida legalmente com a madeira amazônica no Brasil. O fator de emissão de CO2 da madeira serrada da Amazônia pode fundamentar políticas públicas para sua mitigação na atividade madeireira, bem como pautar iniciativas do setor público, construção civil e consumidores. A destruição da floresta foi identificada como a principal influência no fator de emissão de CO2 da madeira serrada. Para mitigação do CO2 nessa etapa, o modelo convencional de exploração precisaria ser revisto, o que conjuntamente promoveria a conservação da floresta. O aproveitamento de resíduos de floresta e serraria configura outra oportunidade relevante para a redução de impacto ambiental do produto. A parcela de contribuição da produção de madeira serrada Amazônica sobre as emissões brasileiras de 2005 foi estimada entre 3,5% e 13,1%. Para a proposição de ações eficazes, o impacto de diversos modelos de exploração madeireira precisa ser medido e sua análise ser aprofundada, para as diferentes regiões da floresta Amazônica. / Environmental information of materials and products are essential for sustainability management in construction. Due to climate change, CO2 emission of products are relevant to inventory buildings and projects and to guide professionals\' and consumers decisions. Based on Material Flow Analysis, this research aim to quantify CO2 emission factor of Amazon lumber from conventional logging. The study included stages of logging, transportation of logs, sawing and lumber transportation. CO2 emissions from residues of biomass and energy consumption were considered in quantification. The results are presented in ranges for each stage of chain production, in order to incorporate uncertainties and variations of forest characteristics and procedures. Quantification was mainly based on literature; interviews with logging companies were used to define energy consumption. Amazon rainforest is composed of 200 t/ha to 425 t/ha of above ground dry biomass, which depends on forest region, and stocks between 98 tC/ha and 208 tC/ha. In conventional logging 3-9 trees per hectare are usually extracted, estimated as 4% to 14% of forest biomass. During logging, from 7% to 33% of the forest biomass is damaged to open trails, fall trees and remove commercial logs. The damaged biomass is usually left at forest, where it decomposes, causing CO2 emissions. In sawmills, at least 54% of the biomass is transformed into residues, which are burned or degraded, other CO2 source. Combining forest and sawmill residues, from 5.0 t residues/ t lumber to 8.5 t/t are generated. The CO2 emissions from residues of biomass, per unit of processed roundwood, are estimated from 3.4 tCO2/t to 9.7 tCO2/t. Energy consumed in extraction, logs transportation and sawing contribute with 0.02 tCO2/t to 0.12 tCO2/t of processed roundwood. At the end of the production, emissions were estimated from 7.5 tCO2/t to 28.4 tCO2/t of lumber, equivalent to 5.2 tCO2/m³ to 19.6 tCO2/m³. Lumber transportation from sawmills to consumer market is another stage that increases emissions from 0.03 tCO2/t to 0.12 tCO2/t of lumber, if admitted 1,956 km, the estimated average distance for legal Amazon lumber transportation in Brazil. CO2 emission factor of Amazon lumber may contribute to mitigation policies in wood sector, as well as guide initiatives of public sector, construction sector and consumers. The destruction of forest biomass was identified as the main influence on CO2 emission factor of Amazon lumber. To minimize CO2 emissions the conventional model of exploitation need to be revised, what would also promote Amazon rainforest conservation. The use of residues from forest and sawmills is another relevant opportunity to reduce environmental impact of lumber. The contribution of Amazon lumber in Brazilian CO2 emissions, based on 2005 data, was estimated from 3.5% to 13.1%. To propose effective actions, the impact of logging in different models of exploitation must be measured in different regions of Amazon forest.
98

Sistemas microfluídicos amperométricos utilizando enzimas imobilizadas / Amperometric microfluidic systems using immobilized enzymes

Luís Marcos Cerdeira Ferreira 05 May 2011 (has links)
Este trabalho descreve o desenvolvimento de um sistema microfluídico, contendo, como componente principal, um reator enzimático constituído de um microcanal fabricado em substrato de poli(metacrilato de metila) e um sistema amperométrico como detector. Para a construção de microcanais foi utilizando equipamento de usinagem a laser de CO2 para escavar os microcanais, que a seguir foram selados termicamente. A superfície interna desse microcanal foi submetida à modificação química com poli(etilenoimina), que se mostrou eficiente para posterior imobilização da enzima glicose oxidase, utilizando glutaraldeído como agente de ligação covalente cruzada, gerando assim um microrreator para determinação amperométrica de glicose. O peróxido de hidrogênio gerado na reação enzimática foi detectado em uma célula eletroquímica em fluxo, localizada externamente ao reator, com eletrodo de platina como eletrodo de trabalho. Uma bomba peristáltica programável foi empregada para promover a injeção de amostra, utilizando tubulação de pequeno diâmetro (0,3 mm), permitindo alcançar reprodutibilidade para a injeção de pequenos volumes, tipicamente da ordem de 5 microlitros de solução. O sistema proposto foi utilizado para a determinação amperométrica diferencial de glicose presente em amostras de refrigerantes, apresentando boa repetibilidade (DPR = 1,72%, n = 50), limite de detecção apreciável (1,40 x10-6 mol L-1), elevada frequência de amostragem (345 amostras h-1) e relativa estabilidade a longo prazo (420 determinações em mais de 20 dias com perda de atividade menor que 50%). As análises realizadas com o sistema proposto neste estudo levaram a resultados concordantes com os obtidos pelo método espectrofotométrico clássico, utilizado para análise de glicose em fluídos biológicos. / This work describes the development of a microfluidic system having as a main component an enzymatic reactor constituted by a microchannel assembled in poly(methyl methacrylate) substrate, connected to an amperometric detector. To manufacture the microchannels, a CO2 laser ablation machine was utilized to engrave the channels, which in sequence were thermally sealed. The internal surfaces of the microchannels were chemically modified with poly(ethyleneimine) which showed good effectiveness for the immobilization of glucose oxidase enzymes using glutaraldehyde as crosslinking agent, producing in this way a microreactor effective for the amperometric detection of glucose. The hydrogen peroxide generated in the enzymatic reaction was detected in the electrochemical flow cell, localized outside of the reactor, using platinum as the working electrode. A programmable peristaltic pump was utilized to inject the samples, utilizing tubes with small diameter (0.3 mm), allowing attain reproducibility even for injections of small volumes, in the order of 5 microliters of solution. The proposed system was applied for differential amperometric determination of glucose content in soft drinks, showing good repeatability (DPR = 1.72%, n = 50) low detection limit (1,40 x10-6 mol L-1), high sample frequency (345 samples h-1) and relatively good stability for long term (420 determinations along more than 20 days, with a decrease of activity lower than 50%). The analysis performed with the system proposed in this study lead to results which agree with those obtained by the classical spectrophotometric method, utilized to analyze glucose in biological fluids.
99

Metabolismo de um município brasileiro de pequeno porte : o caso de Feliz, RS / Metabolism of a small Brazilian municipality : Feliz, RS, case study

Kuhn, Eugenia Aumond January 2014 (has links)
Estudos relacionados ao consumo de recursos e à emissão de resíduos na escala territorial local se originaram nas pioneiras pesquisas associadas ao conceito de metabolismo urbano. Nos últimos 15 anos, observa-se um crescimento do número de estudos aplicados a cidades, municípios ou regiões metropolitanas. A Análise dos Fluxos de Materiais - AFM (Material Flow Analysis) vem se consolidando como a abordagem metodológica predominante para esse tipo de investigação, a qual objetiva prover informações sobre fluxos de materiais e de energia, usualmente em unidades de massa, entrando e deixando uma sociedade. No entanto, todos os casos estudados na literatura prévia correspondem a capitais nacionais ou a municípios com centralidade econômica e de gestão do território na região as quais pertencem. Adicionalmente, não há estudos desenvolvidos no Brasil. Em face dessas lacunas, o objetivo principal deste trabalho é a caracterização dos fluxos de materiais associados ao metabolismo de um município brasileiro de pequeno porte (MBPP). Para tanto se adotou como estudo de caso o município de Feliz-RS. Como objetivos intermediários da pesquisa estabeleceram-se: a) Identificação dos métodos existentes para caracterização de fluxos de materiais na escala local e análise das possibilidades de aplicação no contexto dos MBPP; b) Desenvolvimento de um detalhamento metodológico da AFM, para a caracterização dos fluxos de materiais de MBPP; c) Análise das limitações e oportunidades para uso da AFM, na avaliação de sustentabilidade ambiental de municípios. Como resultados, avalia-se que o detalhamento metodológico desenvolvido é funcional e replicável para municípios brasileiros com o mesmo perfil, além de fornecer informações bastante detalhadas acerca dos fluxos ocorrentes no município adotado como caso. Assim, é possível realizar análises com diferentes níveis de desagregação. Quanto aos fluxos de materiais de Feliz, encontrou-se que o consumo doméstico de materiais per capita (DMC/ per capita) do município é alto, se comparado àqueles já caracterizados na literatura. Essa constatação corrobora com a proposição de que municípios com produção primária e secundária tendem a demandar, proporcionalmente, mais recursos do que aqueles que são consumidores finais. Quanto ao uso da AFM, na avaliação de sustentabilidade ambiental, verifica-se um alto potencial, com vantagens, em relação a outros métodos correntemente adotados. Entretanto, essas oportunidades ainda são pouco exploradas no contexto internacional e ignoradas no Brasil, ao se analisar a literatura existente. / Studies related to resources consumption and wastes emissions in a local territorial scale were originated from pioneering researches related to the urban metabolism concept. Over the past 15 years, there was a growth in the number of such studies applied to cities, municipalities and metropolitan areas. At the same time, Material Flow Analysis - MFA was consolidated as the predominant methodological approach for this type of research. However, it must be pointed out that all studied cases have been related to national capitals or counties, with economics centrality and land management in their own area. Besides, no studies of this nature were found as being developed in Brazil. Thus, the main goal of the research presented in this paper was to characterize material flows associated with the metabolism of a small Brazilian municipality and for this purpose the municipality of Feliz was adopted as a case study. Three intermediate objectives were established: a) To identify existing methods for material flows characterization on the local scale and to analyse the possibilities of applying them in the context of small Brazilian municipalities; b) to develop a MFA methodological detailing for the characterization of material flows of small Brazilian municipalities; c) to analyse constraints and opportunities for the use of MFA in the assessment of municipalities environmental sustainability. As results, it is considered that the methodological detailing developed raises the possibility of replicating the procedures applied in Feliz to other Brazilian municipalities, being this research a first and referential step in this direction. Besides, it provides very detailed information on flows occurring in the municipality adopted as the case study. Thus, it is possible ti further develop of analyses considering different levels of disaggregation. Concerning the material flows associated with the metabolism of Feliz, it was found that the studied municipality presents a DMC per capita comparable or superior to that of larger municipalities already analyzed by previous researches. This finding corroborates the hypothesis that municipalities with primary and secondary production tend to demand proportionately more resources than those who are the final consumers. Regarding the use of the MFA in the assessment of municipalities environmental sustainability, it was verified that it presents a high potential, with advantages over other methods currently adopted. However, when analyzing the existing literature it was noticed that these opportunities are still little explored in the international context and ignored in Brazil.
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En rörig historia : en fallstudie över Secorocs processflöde av DTH-rör

Forsman, Kristoffer January 2010 (has links)
<p><strong>Abstract</strong></p><p><strong> </strong><strong>Title: </strong>A messy story – a case study of Secorocs process flow of DTH-pipes</p><p><strong> </strong><strong>Presentation date: </strong>2010-06-02<strong> </strong></p><p><strong></strong><strong>Course: </strong>Bachelor thesis in business</p><p><strong></strong><strong>Author: </strong>Kristoffer Forsman</p><p><strong></strong><strong>Advisor: </strong>Kjell Gustafsson</p><p><strong></strong><strong>Keywords:</strong> Management control, process control, lean production, process flow analysis</p><p><strong></strong></p><p><strong>Purpose: </strong>The purpose of this bachelor thesis is to develop an overview of the process flow for a specific product, and with the help of this mapping based on a lean production philosophy show possible improvement proposals and how these can lead to a more efficient process flow.</p><p><strong></strong></p><p><strong>Methodology: </strong>I have used a case study of Secorocs DTH-pipes and my primary data are gathered through interviews and observations. I have used theoretical framework to establish a process flow analysis. This is to obtain data on process activities and whether they are creating value or not. This leads to a current mapping of the situation in Secoroc on DTH-pipes and then analyzed and suggestions for improvement are developed.</p><p><strong></strong></p><p><strong>Conclusions: </strong>That by using the above mentioned mapping of process flow of DTH-pipes, problem areas could be illustrated. Subsequently proposals for improvement could be produced from a lean production philosophy. Process flow analysis showed the non-value-adding process activities as primarily transport and delay. These activities could be rationalized and eliminated from developed proposals for improvement which resulted in a layout flowchart (bilaga3) as a proposal on how a better flow might look for Secoroc.</p>

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