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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.
51

Effect of initial microstructure on the deformation and annealing behaviour of low carbon steel.

Xu, Wanqiang, Materials Science & Engineering, Faculty of Science, UNSW January 2006 (has links)
The effect of initial microstructures of an 0.05 wt.% C low carbon steel, acicular ferrite (AF), Bainite (B), polygonal ferrite (PF), fine polygonal ferrite (FPF), and a microstructure produced by direct strip casting (DSC) (termed SC), on the deformation and recrystallization behaviour of cold rolled low carbon (LC) steel, was investigated. The initially prepared samples with the initial microstructures were cold rolled to 50, 70 and 90% reductions, then annealed isothermally in the temperature range 580 ??? 680 oC. The microstructures and textures produced by deformation and annealing were studied by optical microscopy, XRD, TEM, SEM and EBSD. The initial microstructures were characterized mainly by optical microscopy and EBSD. Using EBSD, the ferrite grain size of the AF, B and SC samples was considerably larger than that found by optical microscopy with a large fraction of low angle grain boundaries (LAGBs) observed within prior austenite grains. All samples exhibited a very weak texture close to random. After cold rolling, the microstructures of AF and SC contained shear bands with PF and FPF generating deformation bands. For AF and SC, the pearlite phase was more extensively elongated in rolling direction compared with PF and FPF. After 90% cold rolling reduction, PF, FPF and SC consist mainly of the texture component and AF and B . It was found that FPF recrystallized most rapidly followed by B, PF and AF with SC recrystallizing orders of magnitude more slowly due to the solution drag caused by its uniformly distributed higher Mn content. Very strong (???-fibre) texture was generated in cold rolled PF followed by FPF, with AF, SC and B generating very weak textures. The texture evolution during annealing 90% reduction PF was examined in further detail. The behaviour of nucleation and grain growth provides strong evidence of orientated nucleation as the dominant factor for CRA texture development in this material.
52

Caracterização da resistência à deformação a quente do aço baixo carbono microligado ao vanádio / Carachterization of the hot deformation resistance of a low carbon steel microalloyed with vanadium

Cunha, Emerson Fernandes da January 2009 (has links)
Este trabalho, realizado em cooperação com a Gerdau Riograndense, tem por finalidade avaliar o comportamento do aço GG1013-M, um aço baixo teor de carbono microligado com vanádio e manganês, na laminação a quente no que tange a sua resistência à deformação, possibilitando assim a tomada de decisão em relação a modificações no processo. Foram realizados testes em simulador termomecânico Gleeble™ para determinação das temperaturas a serem usadas no teste prático no laminador, onde testou-se lotes que cobrissem toda a amplitude da faixa de composição química da qualidade do aço em estudo. No teste prático no laminador, foram retiradas amostras para os ensaios mecânicos, onde identificou-se, por intermédio do tratamento de dados em software estatístico, a influência da variação dentro da faixa da composição química sobre os limites de escoamento e resistência. Como resultado, conseguiu-se determinar a faixa de temperatura mais provável, onde a resistência a deformação a quente é menor, minimizando ou eliminando as conseqüências da redução de ductilidade a quente por conta do endurecimento da matriz por precipitação dos elementos de liga em forma de compostos. / This work was conducted in cooperation with Gerdau Riograndense aiming at the evaluation of the hot rolling behavior of a low carbon steel microalloyed with manganese and vanadium (internally GG1013-M steel).The deformation resistance was evaluated, allowing for the decision in relation to changes in the process. A thermomechanical simulator GleebleTM was used to determine the temperatures to be used in practical tests in the rolling mill, where it was tested different material batches covering the large range of chemical compositions for this kind of steel. Mechanical tests were performed on samples taken from the practical tests in the rolling mill. From this tests the influence of chemical composition variation on the yeld strength and maximum stress was studied. As a result, we were able to determine the most likely range of temperatures for a minimization of hot strentgh, therefore also minimizing or eliminating the consequences of the reduction in the hot ductility due precipitation hardening of the matrix.
53

Power to the People: Assessing Renewable Energy Cooperatives in Ontario

Ogunleye, Olaoluwa 15 August 2018 (has links)
There is need for increased production of electricity from renewable energy technologies. The transition to a low-carbon economy, whilst achieving energy security and meeting the Sustainable Development Goal 7 (SDG7) is an ongoing challenge for many countries. Local communities instituting an energy co-operative model may be instrumental to reducing greenhouse gas emissions to attain the 2030 goal. Renewable energy co-operatives (RECs) are one approach that can contribute to environmentally and socially equitable energy transitions in order to meet the SDG7. This thesis examines the factors that affect the success of RECs within Ontario to better discern how RECs are set up and how government policy affects their development. The main research question of this study is “How can Ontario’s renewable energy co-ops grow, experience long-term viability, be updated or expanded?” This thesis argues that the quest towards energy transition, a low-carbon economy and to achieve both the federal and provincial targets by 2030 should take on a multi-stakeholders approach. In theory, this should reflect community desires, goals and energy equity since a community should have its own supported role in energy generation towards the whole of Ontario. With the absence of provincial support from the removal of the Feed-In Tariff (FIT) program in 2017, it is now imperative that municipal governments become involved in REC developments within their community. The methodological approach of this thesis uses a combination of the Strengths, Weaknesses, Opportunities and Threats (SWOT) and sustainability analyses in order to interpret the data collected from semi-structured interviews with co-ops and policymakers as well as their websites and reports. This study examines the support structures and barriers for the growth of RECs in Ontario and how their growth can contribute to the SDG7. Through document review and interviews with representatives from the co-ops, I discovered that barriers include unstable government policy, inadequate funding, and a lack of support from financial institutions due to the smaller size of the projects developed by power co-ops. Comparisons with REC policy and progress in European countries show Ontario can do more to support RECs. This thesis concludes that one of the many available options for Ontario to contribute substantially to the transition to a low-carbon-economy is through applying the Pan-Canadian Framework on Clean Growth and Climate Change and the SDG7 by supporting citizen-led initiatives like RECs and to encourage large financial institutions to invest in their communities.
54

Inibidores orgânicos de corrosão : estudos com compostos naturais obtidos de diversas espécies de mentas

Grosser, Fabiana Nogueira January 2015 (has links)
O comportamento eletroquímico do aço carbono em soluções aquosas contendo KNO3 0,10 mol L-1 e soluções etanólicas contendo cloreto de tetraetilamônio 0,10 mol L-1 foi estudado na ausência e na presença de diferentes concentrações (0,50 mM a 50,0 mM) de acetato de linalila, mentol, limoneno e pulegona. Técnicas eletroquímicas como a potenciometria, varredura potenciodinâmica, cronoamperometria, curvas de Tafel e espectroscopia de impedância eletroquímica foram utilizadas a fim de compreender a interação entre os compostos orgânicos e a superfície do eletrodo. Medidas de perda de massa também foram realizadas, bem como a comprovação visual dos resultados mediante registros fotográficos. O acetato de linalila adsorve na superfície do aço carbono mesmo na presença de grande quantidade de água ou etanol. A energia livre de adsorção de Gibbs para este processo é de -26,0 kJ mol-1 em soluções aquosas e -26,7 kJ mol-1 em soluções etanólicas. Para o mentol, a energia livre de adsorção de Gibbs calculada foi de -26,7 kJ mol-1 em soluções aquosas e -24,2 kJ mol-1 em soluções etanólicas. Para o limoneno, esses valores foram -24,2 kJ mol-1 em meio aquoso e -26,0 kJ mol-1 em meio etanólico, e para a pulegona os valores foram de -25,7 kJ mol-1 e -24,6 kJ mol-1, em meio aquoso e etanólico, respectivamente. Foi detectado que as espécies adsorvidas na superfície do metal diminuíram os valores das densidades de corrente anódicas, bem como a perda de massa do metal. Esses efeitos permitem-nos classificar esses compostos orgânicos como inibidores naturais de corrosão para o aço carbono em soluções aquosas e etanólicas. / The electrochemical behavior of low carbon steel in aqueous solutions containing KNO3 0.10 mol L-1 and ethanolic solutions containing tetraethylammonium chloride 0.10 mol L-1 was studied in the absence and presence of different concentrations (0.50 mM to 50.0 mM) of linalyl acetate, menthol, limonene and pulegone. Electrochemical techniques such as potentiometry, cyclic voltammetry, chronoamperometry, Tafel curves and electrochemical impedance spectroscopy were used to understand the interaction between the organic compound and the electrode surface. Weight loss measurements were also performed, as well as visual confirmation of the results by photographic records. Linalyl acetate adsorbed on low carbon steel surface even in the presence of a large amount of water or ethanol. The Gibbs free energy of adsorption for this process was -26.0 kJ mol-1 in aqueous solutions and -26.7 kJ mol-1 for ethanol solutions. For menthol, the Gibbs free energy of adsorption was calculated -26.7 kJ mol-1 in aqueous solutions and -24.2 kJ mol-1 for ethanol solutions. For limonene, these values were -24.2 kJ mol-1 in aqueous medium and -26.0 kJ mol-1 in ethanolic medium, and for pulegone the values were - 25.7 kJ mol-1 and -24.6 kJ mol-1 in aqueous and ethanolic medium, respectively. It was detected that the species adsorbed on the metal surface decreased the amounts of anodic current densities and the metal mass loss. These effects allow us to classify the organic compounds investigated as natural corrosion inhibitors for low carbon steel in aqueous and ethanolic solutions.
55

Investigating patterns of local climate governance: How low-carbon municipalities and intentional communities intervene in social practices

Hausknost, Daniel, Haas, Willi, Hielscher, Sabine, Schäfer, Martina, Leitner, Michaela, Kunze, Iris, Mandl, Sylvia 11 1900 (has links) (PDF)
The local level has gained prominence in climate policy and governance in recent years as it is increasingly perceived as a privileged arena for policy experimentation and social and institutional innovation. However, the success of local climate governance in industrialized countries has been limited. One reason may be that local communities focus too much on strategies of technology-oriented ecological modernization and individual behavior change and too little on strategies that target unsustainable social practices and their embeddedness in complex socioeconomic patterns. In this paper we assess and compare the strategies of "low-carbon municipalities" (top-down initiatives) and those of "intentional communities" (bottom-up initiatives). We were interested to determine to what extent and in which ways each community type intervenes in social practices to curb carbon emissions and to explore the scope for further and deeper interventions on the local level. Using an analytical framework based on social practice theory we identify characteristic patterns of intervention for each community type. We find that low-carbon municipalities face difficulties in transforming carbon-intensive social practices. While offering some additional low-carbon choices, their ability to reduce carbon-intensive practices is very limited. Their focus on efficiency and individual choice shows little transformative potential. Intentional communities, by contrast, have more institutional and organizational options to intervene in the web of social practices. Finally, we explore to what extent low-carbon municipalities can learn from intentional communities and propose strategies of hybridization for policy innovation to combine the strengths of both models.
56

Caracterização da resistência à deformação a quente do aço baixo carbono microligado ao vanádio / Carachterization of the hot deformation resistance of a low carbon steel microalloyed with vanadium

Cunha, Emerson Fernandes da January 2009 (has links)
Este trabalho, realizado em cooperação com a Gerdau Riograndense, tem por finalidade avaliar o comportamento do aço GG1013-M, um aço baixo teor de carbono microligado com vanádio e manganês, na laminação a quente no que tange a sua resistência à deformação, possibilitando assim a tomada de decisão em relação a modificações no processo. Foram realizados testes em simulador termomecânico Gleeble™ para determinação das temperaturas a serem usadas no teste prático no laminador, onde testou-se lotes que cobrissem toda a amplitude da faixa de composição química da qualidade do aço em estudo. No teste prático no laminador, foram retiradas amostras para os ensaios mecânicos, onde identificou-se, por intermédio do tratamento de dados em software estatístico, a influência da variação dentro da faixa da composição química sobre os limites de escoamento e resistência. Como resultado, conseguiu-se determinar a faixa de temperatura mais provável, onde a resistência a deformação a quente é menor, minimizando ou eliminando as conseqüências da redução de ductilidade a quente por conta do endurecimento da matriz por precipitação dos elementos de liga em forma de compostos. / This work was conducted in cooperation with Gerdau Riograndense aiming at the evaluation of the hot rolling behavior of a low carbon steel microalloyed with manganese and vanadium (internally GG1013-M steel).The deformation resistance was evaluated, allowing for the decision in relation to changes in the process. A thermomechanical simulator GleebleTM was used to determine the temperatures to be used in practical tests in the rolling mill, where it was tested different material batches covering the large range of chemical compositions for this kind of steel. Mechanical tests were performed on samples taken from the practical tests in the rolling mill. From this tests the influence of chemical composition variation on the yeld strength and maximum stress was studied. As a result, we were able to determine the most likely range of temperatures for a minimization of hot strentgh, therefore also minimizing or eliminating the consequences of the reduction in the hot ductility due precipitation hardening of the matrix.
57

O Plano e Programa ABC: uma avaliação da execução e distribuição dos recursos / The ABC Plan and Program: an evaluation of the execution and distribution of resources

Giovani William Gianetti 26 January 2018 (has links)
A importância das mudanças climáticas no cenário econômico-político internacional é crescente e os esforços para a geração e utilização de tecnologias de baixa emissão de carbono vêm se ampliando. Neste sentido que o Plano ABC é implementado nas propriedades rurais através de linha de Crédito Rural denominada Programa ABC. Os estados e municípios brasileiros possuem grandes disparidades econômicas e edafoclimáticas, apresentando adoção heterogênea de tecnologia no meio rural. Deste modo, o presente trabalho visa analisar a execução e distribuição dos recursos do Plano e Programa ABC, avaliando a aplicação destes de modo a atender os objetivos do projeto. Serão utilizadas informações dos empréstimos do Programa ABC de 2013 a 2016 obtidos através do SICOR, variáveis de desempenho da agropecuária obtidas com o IBGE e classificação de aptidão agrícola predominante nos municípios realizada por Sparovek (2015) para a obtenção de estatísticas e correlação de Spearman. Os resultados demonstram que as linhas de financiamento do ABC Recuperação, ABC Plantio Direto, ABC Florestas e ABC Integração correspondem à parcela superior a 98% do volume de crédito concedido. A maioria dos recursos é absorvida pelo Centro-Oeste e Sudeste. As regiões Norte e Nordeste possuem maior carência em produtividade agropecuária, portanto, os empréstimos do ABC nestas regiões resultariam em maiores impactos de mitigação de GEE, mas o volume de recursos destinado para as mesmas é baixo. Os resultados mostram que os recursos são destinados em sua maioria a municípios que possuem maior aptidão agrícola e assim devem propiciar menores efeitos de mitigação de GEE. Calculou-se que os empréstimos são mais fortemente relacionados com o rebanho bovino do que com as pastagens degradadas. Além disto, os investimentos realizados nas regiões de aptidão agrícola mais elevada possuem maior correlação com características econômicas. Para ampliar a eficiência da execução e distribuição dos recursos do Plano e Programa ABC, alterações que contemplem a possibilidade de aderência a múltiplos sistemas produtivos e a diferenciação de incentivos conforme definições de áreas prioritárias poderiam ser realizadas. / The importance of climate change in the international economic and political scenario is growing, and efforts for the generation and use of low-carbon technologies have been expanding. In this sense, the ABC Plan is implemented in rural properties through the rural crédit line called the ABC Program. The brazilian states and municipalities have great economic and edaphoclimatic disparities, presenting heterogeneous adoption of technology in rural areas. Thus, the present work aims to analyze the execution and distribution of resources of the ABC Plan and Program, evaluating their application in order to meet the project objectives. Information from the ABC Program loans from 2013 to 2016 obtained through SICOR, agricutural performance variables obtained with the IBGE and the calssification of predominant agricultural aptitude in the municipalities by Sparovek (2015) will be used to obtain statistics and Spearman correlation. Results show that the loans of ABC Recovery, ABC Direct Planting, ABC Forests and ABC Integration correspond up to 98% of the volume of credit granted. Most of the resources are absorbed by the Midwest and Southeast regions. The North and Northeast regions have greater deficiencies in agricultural productivity, therefore, the ABC loans in these regions would result in greater impacts of GHG mitigation, but the volume of resources allocated to them is low. Results show also that resources are mostly destined to municipalities that have greater agricultural aptitude and thus should provide less mitigation effects of GHG. Loans were estimated to be more strongly correlated to the cattle herd than to degraded pastures. In addition, investments made in regions with the highest agricultural aptitude have a higher correlation with economic characteristics. In order to increase the efficiency of the execution and distribution of the resources of the ABC Plan and Program, changes that contemplate the possibility of adherence to multiple productive systems and the differentiation of incentives according to definitions of priority areas could be realized.
58

Estudo da evolução da textura, da microtextura e da mesotextura de recristalização, após baixos graus de deformação a frio, em dois aços ferríticos com baixo teor de carbono

LIMA, LIANA M.F.G. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:50:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:06Z (GMT). No. of bitstreams: 1 10457.pdf: 13419642 bytes, checksum: 823b4f1fc4fdfe5858d116b42196a9c2 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
59

inibidores orgânicos de corrosão : estudos com compostos naturais obtidos de diversas espécies de mentas

Grosser, Fabiana Nogueira January 2015 (has links)
O comportamento eletroquímico do aço carbono em soluções aquosas contendo KNO3 0,10 mol L-1 e soluções etanólicas contendo cloreto de tetraetilamônio 0,10 mol L-1 foi estudado na ausência e na presença de diferentes concentrações (0,50 mM a 50,0 mM) de acetato de linalila, mentol, limoneno e pulegona. Técnicas eletroquímicas como a potenciometria, varredura potenciodinâmica, cronoamperometria, curvas de Tafel e espectroscopia de impedância eletroquímica foram utilizadas a fim de compreender a interação entre os compostos orgânicos e a superfície do eletrodo. Medidas de perda de massa também foram realizadas, bem como a comprovação visual dos resultados mediante registros fotográficos. O acetato de linalila adsorve na superfície do aço carbono mesmo na presença de grande quantidade de água ou etanol. A energia livre de adsorção de Gibbs para este processo é de -26,0 kJ mol-1 em soluções aquosas e -26,7 kJ mol-1 em soluções etanólicas. Para o mentol, a energia livre de adsorção de Gibbs calculada foi de -26,7 kJ mol-1 em soluções aquosas e -24,2 kJ mol-1 em soluções etanólicas. Para o limoneno, esses valores foram -24,2 kJ mol-1 em meio aquoso e -26,0 kJ mol-1 em meio etanólico, e para a pulegona os valores foram de -25,7 kJ mol-1 e -24,6 kJ mol-1, em meio aquoso e etanólico, respectivamente. Foi detectado que as espécies adsorvidas na superfície do metal diminuíram os valores das densidades de corrente anódicas, bem como a perda de massa do metal. Esses efeitos permitem-nos classificar esses compostos orgânicos como inibidores naturais de corrosão para o aço carbono em soluções aquosas e etanólicas. / The electrochemical behavior of low carbon steel in aqueous solutions containing KNO3 0.10 mol L-1 and ethanolic solutions containing tetraethylammonium chloride 0.10 mol L-1 was studied in the absence and presence of different concentrations (0.50 mM to 50.0 mM) of linalyl acetate, menthol, limonene and pulegone. Electrochemical techniques such as potentiometry, cyclic voltammetry, chronoamperometry, Tafel curves and electrochemical impedance spectroscopy were used to understand the interaction between the organic compound and the electrode surface. Weight loss measurements were also performed, as well as visual confirmation of the results by photographic records. Linalyl acetate adsorbed on low carbon steel surface even in the presence of a large amount of water or ethanol. The Gibbs free energy of adsorption for this process was -26.0 kJ mol-1 in aqueous solutions and -26.7 kJ mol-1 for ethanol solutions. For menthol, the Gibbs free energy of adsorption was calculated -26.7 kJ mol-1 in aqueous solutions and -24.2 kJ mol-1 for ethanol solutions. For limonene, these values were -24.2 kJ mol-1 in aqueous medium and -26.0 kJ mol-1 in ethanolic medium, and for pulegone the values were - 25.7 kJ mol-1 and -24.6 kJ mol-1 in aqueous and ethanolic medium, respectively. It was detected that the species adsorbed on the metal surface decreased the amounts of anodic current densities and the metal mass loss. These effects allow us to classify the organic compounds investigated as natural corrosion inhibitors for low carbon steel in aqueous and ethanolic solutions.
60

Inibidores orgânicos de corrosão : estudos com compostos naturais obtidos de diversas espécies de mentas

Grosser, Fabiana Nogueira January 2015 (has links)
O comportamento eletroquímico do aço carbono em soluções aquosas contendo KNO3 0,10 mol L-1 e soluções etanólicas contendo cloreto de tetraetilamônio 0,10 mol L-1 foi estudado na ausência e na presença de diferentes concentrações (0,50 mM a 50,0 mM) de acetato de linalila, mentol, limoneno e pulegona. Técnicas eletroquímicas como a potenciometria, varredura potenciodinâmica, cronoamperometria, curvas de Tafel e espectroscopia de impedância eletroquímica foram utilizadas a fim de compreender a interação entre os compostos orgânicos e a superfície do eletrodo. Medidas de perda de massa também foram realizadas, bem como a comprovação visual dos resultados mediante registros fotográficos. O acetato de linalila adsorve na superfície do aço carbono mesmo na presença de grande quantidade de água ou etanol. A energia livre de adsorção de Gibbs para este processo é de -26,0 kJ mol-1 em soluções aquosas e -26,7 kJ mol-1 em soluções etanólicas. Para o mentol, a energia livre de adsorção de Gibbs calculada foi de -26,7 kJ mol-1 em soluções aquosas e -24,2 kJ mol-1 em soluções etanólicas. Para o limoneno, esses valores foram -24,2 kJ mol-1 em meio aquoso e -26,0 kJ mol-1 em meio etanólico, e para a pulegona os valores foram de -25,7 kJ mol-1 e -24,6 kJ mol-1, em meio aquoso e etanólico, respectivamente. Foi detectado que as espécies adsorvidas na superfície do metal diminuíram os valores das densidades de corrente anódicas, bem como a perda de massa do metal. Esses efeitos permitem-nos classificar esses compostos orgânicos como inibidores naturais de corrosão para o aço carbono em soluções aquosas e etanólicas. / The electrochemical behavior of low carbon steel in aqueous solutions containing KNO3 0.10 mol L-1 and ethanolic solutions containing tetraethylammonium chloride 0.10 mol L-1 was studied in the absence and presence of different concentrations (0.50 mM to 50.0 mM) of linalyl acetate, menthol, limonene and pulegone. Electrochemical techniques such as potentiometry, cyclic voltammetry, chronoamperometry, Tafel curves and electrochemical impedance spectroscopy were used to understand the interaction between the organic compound and the electrode surface. Weight loss measurements were also performed, as well as visual confirmation of the results by photographic records. Linalyl acetate adsorbed on low carbon steel surface even in the presence of a large amount of water or ethanol. The Gibbs free energy of adsorption for this process was -26.0 kJ mol-1 in aqueous solutions and -26.7 kJ mol-1 for ethanol solutions. For menthol, the Gibbs free energy of adsorption was calculated -26.7 kJ mol-1 in aqueous solutions and -24.2 kJ mol-1 for ethanol solutions. For limonene, these values were -24.2 kJ mol-1 in aqueous medium and -26.0 kJ mol-1 in ethanolic medium, and for pulegone the values were - 25.7 kJ mol-1 and -24.6 kJ mol-1 in aqueous and ethanolic medium, respectively. It was detected that the species adsorbed on the metal surface decreased the amounts of anodic current densities and the metal mass loss. These effects allow us to classify the organic compounds investigated as natural corrosion inhibitors for low carbon steel in aqueous and ethanolic solutions.

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