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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.
41

Características físicas, químicas e geoquímicas de um depósito de areia descartada de fundição (ADF) e sua implicação ambiental / Fisical, chemical and geochemical characterization of a foundry sand deposit and it\'s environmental implication.

Monteiro, Marcella Martins Cará 24 October 2013 (has links)
A falta de regulamentação ambiental no passado levou muitas indústrias, incluindo as de fundição (geradoras de grandes quantidades de areia de fundição), a destinarem seus resíduos de forma inadequada ao longo dos anos, criando passivos ambientais que perduram até hoje. A periculosidade destes passivos muitas vezes não está diretamente ligada à periculosidade dos resíduos depositados, pois acredita-se que ao longo dos anos, sob a ação do intemperismo, muitas reações químicas ocorrem levando à mobilidade dos elementos químicos presentes no depósito de resíduos. Este trabalho propõe avaliar o comportamento de um depósito de resíduos de areia de fundição não controlado, com mais de 30 anos e a mobilidade de elementos inorgânicos potencialmente tóxicos ao longo de um perfil vertical do depósito, como parte da gestão ambiental de uma área impactada. Para este objetivo foram utilizadas ferramentas como análise de umidade, análise granulométrica, análise morfológica por MEV, análise química qualitativa e quantitativa por MEV-EDS e por FRX. Os elementos químicos analisados foram divididos em grupos de forma a encontrar similaridades. A partir dos resultados obtidos foi possível concluir que os alcalinos, alcalinos terrosos, calcófilos e alguns litófilos (Al, Zr, P, Mn, Ti e V) migraram para a base do perfil e o comportamento do depósito de resíduos pode ser comparado ao comportamento diagênico clássico de evolução pedológica de perfis de solo em rochas em condições tropicais. Além disso, do ponto de vista micromorfológico, granulométrico e químico esse depósito de resíduo não é o mesmo ao longo do perfil vertical escavado e a divisão em blocos (base, meio e topo) só é verificada na análise granulométrica. E, apesar do resíduo ADF não ser considerado classe I, o mesmo pode apresentar risco ao meio ambiente quando depositado em locais não controlados e submetidos a condições climáticas supérgenas tropicais. / The lack of environmental regulation in the past has led many industries, including foundries (that generates large amounts of foundry sand), to place their waste improperly over the years, creating environmental passives that endure today. The danger of these passives is often not directly related to the dangerousness of waste landfilled because it is believed that over the years, under the action of weathering, many chemical reactions occur leading to mobility of chemical elements present in the waste deposit. This work proposes to evaluate the behavior of an uncontrolled waste foundry deposit, with more than 30 years, and the mobility of potentially toxic inorganic elements along a vertical profile of the deposit as part of the environmental management of an impacted area. For this purpose were used tools such as humidity analysis, granulometric analysis, morphological analysis by Scanning Electron Microscopy (SEM), qualitative and quantitative chemical analysis by SEM with Energy Dispersive X-ray Detector (EDX) and X-ray Fluorescence. The chemicals analyzed were divided into groups in order to find similarities. From the results obtained it was concluded that the alkali, alkaline earth, chalcophile and some lithophile (Al, Zr, P, Mn, Ti e V) migrated to the base of the profile and behavior of the waste deposit can be compared to the classic diagenic behavior of pedological evolution of soil profiles in rocks in tropical conditions. Furthermore, from the standpoint of micromorphology, particle size and chemical this waste deposit is not the same along the vertical profile excavated and the three divisions (base, middle and top) is only checked on granulometric analysis. And despite the foundry sand residue is not considered class I, it may present a risk to the environment when deposited in non-controlled area and subject to tropical supergens weather conditions.
42

As barreiras de entrada de uma inovação sustentável no setor da construção civil de Caxias do Sul : um ensaio exploratório sobre o bloco de concreto fabricado com areia descartada de fundição

Ferrari, Juliano January 2016 (has links)
A constante busca por meios alternativos e economicamente viáveis para a destinação de resíduos industriais trouxe ao setor da construção civil diversas possibilidades de aplicações, em especial da areia descartada de fundição (ADF). Entretanto, pesquisas recentes apontam que os subprodutos gerados a partir desta reutilização do aglomerado enfrentam barreiras de entrada pelo mercado consumidor. A presente dissertação descreve a realização de um ensaio exploratório sobre as barreiras de entrada do bloco de concreto fabricado a partir da reutilização da areia descartada de fundição no setor da construção civil da cidade de Caxias do Sul (RS). O estudo foi motivado pela constatação da resistência por parte dos membros deste setor ao produto proposto e a identificação do modelo teórico de Ramirez, Gonzalez e Moreira (2013) que confirma o fenômeno mercadológico constatado. Executou-se a pesquisa em duas fases dentro do método qualitativo: a primeira, através da realização de entrevistas semiestruturadas em três agentes de análise distintas (fornecedora, representante e especialista); e a segunda, com a realização de um focus group entre membros integrantes do setor da construção civil da cidade de Caxias do Sul. Verificou-se que, embora existam barreiras claramente identificadas no setor pesquisado, a rejeição ao produto proposto se deu principalmente pela falta de estratégias de inserção do produto no mercado consumidor por parte da empresa fabricante, o que confirma o modelo teórico utilizado. / The incessant search for alternative ways and economically viable for the disposal of industrial waste brought to the civil construction sector several possibilities of appliance, particularly regarding the discarded foundry sand (DFS). However, recent researches suggest that sub products generated from this reuse of cluster faces entrance barriers by the consumer market. This essay describes the execution of a case study about the entrance barriers of concrete block made from discarded foundry sand in the civil construction sector at the city of Caxias do Sul (RS). The study was triggered by the verification of the resistance by the members of this sector towards the proposal product and Ramirez, Gonzalez and Moreira´s identification of theoretical model (2013), which confirms the verified marketing phenomenon. The research has been done in two phase, in the qualitative method: the first, throughout semi-structured interviews in three different units of analysis (supplier, dealer and specialist); and the second, with the completion of a focus group between members of the civil construction sector from the city of Caxias do Sul. Has been verified that, although there are barriers clearly identified in the researched sector the rejection on the proposal product occurred mainly by the lack of insertion strategies of the product in the consumer market by the manufacture company, which confirms the theoretical model used.
43

Uma heurística para o problema de dimensionamento de lotes em fundições de mercado / An heuiristic for the lot sizing problem in small market-driven foundries

Viviane Sayuri Tonaki 22 May 2006 (has links)
O setor de fundições é importante para a economia, pois produz componentes básicos para muitos outros setores, de modo que seu bom desempenho tem repercussão nos demais. Um modelo de programação inteira mista para uma fundição de mercado de pequeno porte, que visa principalmente minimizar atrasos na entrega dos pedidos, foi proposto na literatura. Neste trabalho é feito um estudo do modelo e é proposta uma nova abordagem, independente de qualquer software comercial, baseada na decomposição do problema em dois subproblemas: o planejamento da produção das ligas e o planejamento da produção dos itens. Ambos foram resolvidos por uma heurística lagrangiana baseada em transferêrencias. Testes computacionais mostraram que a abordagem proposta é capaz de gerar soluções de boa qualidade, em tempo computacional aceitável / The foundry sector is important to the economy as it produces basic components for many other sectors, to such an extent that its performance has a repercussion in other sectors. A recently published mixed integer-programming model for small market-driven foundries, which aims to minimize delays when delivering orders, was proposed in the literature. In this work, a study of this model was undertaken and a new approach is put forward, regardless of any commercial software, based on dealing with the problem in two sub problems: production planning of alloys and production planning of items. Both sub problems were solved by a Lagrangian heuristic based on transfers. Computational tests show that the approach proposed is able to generate solutions of good quality in acceptable computational time
44

Estudo para a reutilização do resíduo sólido constituído pelas areias de fundição aglomeradas com argila, através da técnica de solidificação/estabilização em matrizes de cimento Portland, para aplicação no setor da construção civil / Study to reuse a solid waste generated by foundry sands bonded with clay, through solidification/stabilization in Portland cement matrices technic, for implementation in the construction industry

Mazariegos Pablos, Javier 30 June 2008 (has links)
A presente pesquisa realizou um estudo que investiga a viabilidade técnica para a reciclagem do resíduo sólido gerado pelo descarte das areias de fundição aglomeradas com argila, para aplicação no setor da construção civil. Para isso, o trabalho estabelece uma metodologia, a qual avalia a estabilização do resíduo em matrizes solidificadas de cimento Portland, melhoradas através de adições de argila bentonita sódica e/ou sílica ativa. A estabilização do resíduo foi verificada através de ensaio de solubilização, o qual submete as matrizes solidificadas a contatos dinâmico e estático com água destilada. Os desempenhos mecânico e físico das matrizes foram avaliados em ensaios de resistência à compressão, absorção de água e permeabilidade ao ar. Os resultados obtidos demonstram que, tanto a bentonita sódica, quanto a sílica ativa contribuem para o aumento da eficiência de fixação dos metais \'AL\', \'FE\' e \'CR\' por parte das matrizes de cimento Portland. As composições que obtiveram os melhores desempenhos mecânico, físico e químico foram utilizadas na confecção de tijolos maciços, visando aplicação na execução de alvenarias. Para a moldagem dos tijolos foi empregada uma prensa hidráulica, o que possibilitou manter a regularidade dimensional das faces. Ao mesmo tempo, o formato dos tijolos foi concebido com design diferenciado, proporcionando modulação e encaixes que podem reduzir significativamente o consumo da argamassa de assentamento. Os tijolos foram submetidos aos ensaios de solubilização, resistência à compressão e absorção de água, apresentando resultados satisfatórios e comprovando a viabilidade técnica para aplicação na execução de alvenarias. / In this research, a study that investigates the technical feasibility for the recycling of solid waste generated by the disposal of the foundry sands bonded with clay, for implementation in the construction industry, was conducted. For this reason, the work establishes a method, which assesses the stabilization of waste in solidified matrices of Portland cement, improved by the additions of sodium bentonite clay and/or silica fume. The stabilization of the waste was verified by solubilization test, which puts the solidified matrices in static and dynamic contacts with distiled water. The mechanical and physical performances of the matrices were evaluated in tests of resistance to compression, absorption of water and air permeability. The results show that both the sodium bentonite, and the active silica contribute to increase the fixation efficiency of the metals \'AL\', \'FE\' and \'CR\' by the matrices of Portland cement. The compositions that have the best mechanical, physical and chemical performance were used in the manufacture of massive bricks, seeking their use in the implementation of masonry. For the molding of bricks a hydraulic press was used, which allowed to keep the dimensional regularity of the faces. At the same time, the format of the bricks was designed with different shapes, providing modulation and fitting that can significantly reduce the consumption of settlement mortar. The bricks were subjected to tests of solubilization, resistance to compression and absorption of water, showing satisfactory results that confirm the technical feasibility for being used in the implementation of masonry.
45

Life Cycle Assessment In Ferrous Foundry Industry

Yigit, Cisem 01 February 2013 (has links) (PDF)
Foundries are most widely facilities all around the world, producing high amounts of castings. In this study, environmental impact of metal foundries was investigated toward a life cycle assessment (LCA) goal. Studies were conducted in two foundry plants in order to collect the inventory data. The difference between the plants regarding their processes was the application of secondary sand reclamation (SSR) in Plant 2. Application of SSR is indicated as a
46

Digital Compositing for Photorealism and Lighting in Chroma key film studio

Andrijasevic, Neda, Johansson, Mirjam January 2012 (has links)
Photorealism is what visual effects are all about most of the time. This report entails digital compositing and studio lighting, in relation to Chroma key film material, aimed to give a photorealistic impression.    One of the identified problems in this report is that compositors may get Chroma key footage where the lighting is done poorly, which means a lot of extra work for the compositors and it might even make it impossible to create the desired end result.    Another problem recognized is that the knowledge that these professions possess is often tacit, not available in texts or even functionally defined.    Considering these problems, the purpose of this report is to articulate and try the tacit knowledge found in respect to these research questions: Which factors can alter the photorealistic impression of filmed Chroma key material? To what extent can different factors be altered in the compositing process, for a photorealistic result? How can a photorealistic result from composited Chroma key material be enabled and facilitated, with focus on studio lighting?       Methods used to answer these questions are interviews with compositors, a case study of a small video production, and the production of video clips, including studio lighting and compositing.    While professionals often write about the importance of consistency in image characteristics between different element that are composited together, this report defines which specific features that ought to be consistent, for a photorealistic result.    Further findings are focused on the limitations of the compositor; i.e. the features that are possible to manipulate and the features that have to be set correctly when filming in the studio, to enable a photorealistic outcome. Nonetheless, the main focus will be on the features of lighting set in the Chroma key film studio.    In fact, there are many features that are crucial for enabling and facilitating the compositing of a photorealistic end product. While some of the findings are new, others confirm what has already been presented.
47

Herman Bergmans Konstgjuteri : Ett ordnings- och förteckningsarbete

von Platen, Wille January 2011 (has links)
This examination paper is the account for the author’s work while arranging and registrating the business archives and business records of the Herman Bergman’s Foundry in Stockholm, Sweden. It is part of the one year Masters program in Archival Science at the University of Uppsala. The records are from the beginning of the 1900s to the 1970s. Most of the business archives are from he 1940s to the 1950s. They contain correspondence with swedish sculptors and press cuttings. The archives include glass plates and photographs that depict the works created at the foundry. Decisions and motivations made during the process are treated in the paper. The author discusses availability and the weeding of business archives.
48

Beitrag zur Qualitätssicherung in Gießereien durch die Anwendung statistischer Methoden

Strehle, Matthias 20 December 2012 (has links) (PDF)
Es werden die Voraussetzungen für die Anwendung statistischer Methoden in Seriengießereien dargestellt. Dazu wurde zunächst anhand einer umfangreichen Literaturrecherche aufgezeigt, dass der Stand der Technik deutliche Defizite aufweist. Für die Verwendung statistischer Methoden, mit dem Ziel der Ausschussreduktion oder Prozessoptimierung, ist eine Datenbank anzulegen, in der jedem Gussteil eindeutig alle qualitätsrelevanten Prozessparameter zugeordnet sind. In Gießereien werden eine Vielzahl von Prozessdaten gemessen und auf unterschiedlichen Computern gespeichert, jedoch ohne Zusammenhang zum Gussteil und dessen Qualität. Eine Zusammenführung der ungenutzten Daten im Nachhinein ist nicht möglich. Die Stoffströme (Sande, Kerne etc.) wurden vom Rohmaterial bis hin zur Gussteilqualität verfolgt (z. B. mit RFID, Infrarotpyrometer). Es wurde ein Ablaufplan über die Vorgehensweise erstellt und in mehreren Gießereien angewandt. Das Ergebnis war eine vollständige Datenbank der Prozessparameter und Gussteilqualitäten, an der mittels statistischer Methoden die Ursachen für Gussfehler identifiziert worden sind.
49

X Band 7 Bit Mmic Phase Shifter Design

Ercil, Erdinc 01 September 2006 (has links) (PDF)
Modern phased array radars require large numbers of electronically controlled phase shifters to steer their beams to the desired direction. The amount of beam steering error depends on the phase resolution of the phase shifters as well as the performance of other parts of the antenna system. The size of the phase shifter in such systems is most of the time needed to be small, which necessitates the MMIC implementation. In the context of this thesis, an X band 7 bit MMIC phase shifter of 2.8125 degree phase resolution, including its layout, is designed using the design kit of OMMIC&reg / Foundry. All bits of the phase shifter are designed to have low return loss so as to minimize the performance egradation due to loading effects upon cascading. Also some structures studied using the design kit of WIN&reg / Foundry are presented. Both designs were performed using ADS&reg / . For the optimum cascading of 7 bits, a MATLAB code was written and used.
50

William Sylvis, pioneer of American labor a study of the labor movement during the era of the civil war,

Grossman, Jonathan, January 1945 (has links)
Issued also as Thesis (Ph. D.)--Columbia University. / Bibliography: p. 285-294.

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