Orientador: Maria Odila Hilário Cioffi / Banca: Marcelo dos Santos Pereira / Banca: Miguel Justino Ribeiro Barboza / Banca: Carlos Antonio Reis Pereira Baptista / Banca: Carlos Moura Neto / Resumo: Na indústria aeronáutica, propriedades como elevada razão resistência mecânica/peso e resistência à corrosão são as razões principais para o uso das ligas de titânio em componentes estruturais, substituindo ligas de alumínio e de aço. Contudo, em componentes mecânicos submetidos ao desgaste, a estrutura hexagonal compacta do titânio somada ao baixo limite de resistência ao cisalhamento requer o uso do material base com um tratamento superficial específico. Os componentes de trem-de-pouso, geralmente submetidos a um ambiente corrosivo sob carregamentos cíclicos, exigem caracterização quanto a resistência à fadiga. Nesta pesquisa é realizado o estudo do comportamento em fadiga da liga Ti-6Al-4V tratada superficialmente em 3 condições: Anodizada, revestida por HVOF com carbeto de tungstênio; e revestida com TiN, CrN e WC por PVD. Os ensaios pino-disco proporcionam uma análise comparativa da resistência ao desgaste dos revestimentos estudados. O principal objetivo deste estudo é avaliar o comportamento em fadiga e ao desgaste da liga Ti-6Al-4V sob diferentes tratamentos superficiais de tal forma que esse material possa substituir as ligas de aço atualmente utilizadas em componentes aeronáuticos. Os resultados mostram que a liga Ti-6Al-4V revestida com WC:H (DLC) por PVD é o melhor sistema de revestimento a ser empregado considerando o desempenho em resistência a fadiga e ao desgaste. / Abstract: In the aeronautical industry, properties as high strength/weight ratio and effective corrosion resistance are primary reasons for the use of titanium alloys in structural components, in the replacement of steel or aluminum alloys. In mechanical components subjected to friction, the titanium hexagonal close packed crystalline structure in addition to the low shear resistance limit the use of the base material as received, then a specific surface treatment is required. Fatigue strength is an important property for components under cyclical loading and corrosive environment as landing gears. This research presented an evaluation of fatigue strength of Ti-6al-4V alloy in three main conditions: anodized, coated by HVOF with WC-10%Co-4% Cr and coated by PVD with TiN, CrN e WC. The pin-disc tests were carried out to obtain a comparative analysis among coatings wear resistance. The main propose of this research is replace the AISI 4340 alloy by Ti-6Al-4V, reducing the aeronautic component weight. Ti-6Al-4V DLC coated by PVD process is the chosen coating system alternative considering fatigue and wear resistance. / Doutor

Made available in DSpace on 2014-10-09T12:25:28Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:56Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Carbon dioxide emissions must be dramatically reduced to avoid the potentially dangerous effects of climate change. The steel and aluminium industries produce large amounts of carbon dioxide, accounting for 6% of anthropogenic emissions. Previous studies have shown that in these industries there is limited scope for further improvements in energy efficiency. Material efficiency strategies can, however, further reduce emissions. This thesis focuses on materially efficient reuse without melting. A scoping study of current reuse found three opportunities, an examination of which forms the basis of this thesis: reusing components at end of product life; extending the lifespan of products; and reusing manufacturing scrap. The opportunity to reuse components has received little attention to date and there is no clearly defined set of strategies or barriers to enable assessment of appropriate component reuse; neither is it possible to predict future levels of reuse. This thesis presents a global assessment of the potential for reusing steel and aluminium components. A combination of top-down and bottom-up analyses is used to allocate the final destinations of current global steel and aluminium production to final products. A substantial catalogue has been compiled for these products characterizing key features of steel and aluminium components including design specifications, requirements in use, and current reuse patterns. To estimate the fraction of end-of-life metal components that could be reused for each product, the catalogue formed the basis of a set of semi-structured interviews with industrial experts. The results suggest that approximately 30% of steel and aluminium used in current products could be reused. Barriers against reuse are examined, prompting recommendations for redesign that would facilitate future reuse. In order to understand how product lifespans can be extended it must first be understood why products are replaced. A simple framework with which to analyse failure is applied to the products that dominate steel use, finding that they are often replaced because a component/sub-assembly becomes degraded, inferior, unsuitable or worthless. In light of this, four products, which are representative of high steel content products in general, are analysed at the component level, determining profiles of cumulative steel mass over the lifespan of each product. The results show that the majority of the steel components are underexploited – still functioning when the product is discarded. In particular, the potential lifespan of the steel-rich structure is typically much greater than its actual lifespan. Evidence from twelve case studies, in which product or component life has been increased, is used to tailor life-extension strategies to each reason for product failure, providing practical guidelines for designers. There is currently no commercial method of reusing small manufacturing scrap; however, previous research has demonstrated that extruded profiles can be created from small clean aluminium scrap, the scrap fragments solid-state welding together when extruded. In order to evaluate potential applications for these profiles four case studies are conducted in collaboration with aluminium producers and product manufacturers. It was found that strong and formable profiles could be produced from scrap. However, contaminated scrap sources, unreliable bonding and poor surface quality limited their potential for commercial use. No model exists for solid-state weld strength that is applicable to scrap extrusion. This prevents optimisation of the existing extrusion process and the development of new, potentially better, processes. Subsequently, this thesis presents a new model of weld strength as a function of relevant deformation parameters. The model is evaluated using a new experiment in which the deformation conditions can be varied independently. The experiments establish the basic relationships between deformation parameters and weld strength. The model correctly predicts these trends with predicted weld strengths typically lying within the experimental error range. The technical assessment of reuse presented in this thesis demonstrates the scope of potential change. If implemented, the opportunities presented would greatly increase the reuse of steel and aluminium, reducing the emissions emitted from liquid metal production in conventional recycling.

Esta dissertação apresenta o Modelo de Componentes CORBA, que é parte da especificação CORBA 3.0. Esse modelo representa uma das mudanças mais significativas em relação às versões anteriores de CORBA. O desenvolvimento de sistemas distribuídos é uma tarefa complexa, envolvendo fatores como a organização de conjuntos de objetos que devem ser implantados e executados em servidores distintos. Aqui estes conjuntos são denominados componentes, conceito já existente em outras especificações, como a dos Enterprise Java Beans. O texto da especificação dos Componentes CORBA, apesar de conter exemplos, mostra-se de difícil compreensão para o desenvolvedor de sistemas. Este trabalho se propõe a facilitar a tarefa de entendimento e utilização de Componentes CORBA, procurando ser didático e ilustrativo o suficiente para que diferentes perfis de leitores possam compreender os diversos conceitos apresentados, seja como uma visão geral, ou ainda como auxílio no desenvolvimento de componentes. / This thesis presents the CORBA Component Model, which is part of the CORBA 3.0 specification. The model is one of the most significant additions with respect to previous versions of CORBA. The development of distributed systems is a complex task, involving factors such as the organization of sets of objects that must be deployed and executed in separate servers. Here, these sets are called components, a concept that already exists in other specifications, such as Enterprise Java Beans. Even though it contains examples, the CORBA Components specification text is not an easy reading for systems developers. Our text intends to facilitate the task of understanding and using CORBA Components, trying to be didactic and illustrative enough so that different profiles of readers are able to understand the many concepts presented, either as an overview, or still as an aid in components development.

The objective of this study is to show the analysis and behavior of symmetrical components and balanced faults in power transformers. Thus, the symmetric component methods solve directly the distribution of voltages and currents, allowing the correct verification of the procedure and the influence of earth circuit faults with the neutral point in distribution transformers. Therefore, the symmetric component analysis procedure has an innovative contribution to the determination of problem solving that solves practical cases and allows to determine the unbalanced failure analysis. / Revisión por pares

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Multiway data are becoming more and more common. While there are many approaches to extending principal component analysis (PCA) from usual data matrices to multiway arrays, their conceptual differences from the usual PCA, and the methodological implications of such differences remain largely unknown. This thesis aims to specifically address these questions. In particular, we clarify the subtle difference between PCA and singular value decomposition (SVD) for multiway data, and show that multiway principal components (PCs) can be estimated reliably in absence of the eigengaps required by the usual PCA, and in general much more efficiently than the usual PCs. Furthermore, the sample multiway PCs are asymptotically independent and hence allow for separate and more accurate inferences about the population PCs. The practical merits of multiway PCA are further demonstrated through numerical, both simulated and real data, examples.

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The study of proteomics holds the hope for detecting serious diseases earlier than is currently possible by analyzing blood samples in a mass spectrometer. Unfortunately, the statistics involved in comparing a control group to a diseased group are not trivial, and these difficulties have led others to incorrect decisions in the past. This paper considers a nested design that was used to quantify and identify the sources of variation in the mass spectrometer at BYU, so that correct conclusions can be drawn from blood samples analyzed in proteomics. Algorithms were developed which detect, align, correct, and cluster the peaks in this experiment. The variation in the m/z values as well as the variation in the intensities was studied, and the nested nature of the design allowed us to estimate the sources of that variation. The variation due to the machine components, including the mass spectrometer itself, was much greater than the variation in the preprocessing steps. This conclusion inspires future studies to investigate which part of the machine steps is causing the most variation.