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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.
131

The evaluation of the repeatability and performance of the cast iron multifacet drill

Chou, Kou-Ching. January 1984 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 126-128).
132

Simulation and interpretation of formation-tester measurements acquired in the presence of mud-filtrate invasion, multiphase flow, and deviated wellbores

Angeles Boza, Renzo Moisés, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2009. / Title from PDF title page (University of Texas Digital Repository, viewed on September 9, 2009). Vita. Includes bibliographical references.
133

Investigation of the effect of waterjet created slots in improving the performance of tricone drill bits in hard rock /

Pederick, Stuart. January 2005 (has links) (PDF)
Thesis (M.Eng.Sc.) - University of Queensland, 2005. / Includes bibliography.
134

Comparison of three drilling technologies to characterize the vadose zone, Hanford Site

Holm, Rochelle Hales, January 2007 (has links) (PDF)
Thesis (M.S. in environmental science)--Washington State University, August 2007. / Includes bibliographical references (p. 19).
135

Characterization of drillability of sandwich structure of carbon fiber reinforced epoxy composite over titanium alloy

Khasawneh, Firas Abdallah. January 2006 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 13, 2007). Vita. Includes bibliographical references.
136

Aspectos da furação do titânio 6Al4V com broca de aço rápido sinterizado e broca de metal duro / Drilling aspects from titanium 6Al4V with sintered high speed steel drill and carbide drill

Allegrini, Alex [UNESP] 14 July 2014 (has links) (PDF)
Made available in DSpace on 2015-03-03T11:52:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-14Bitstream added on 2015-03-03T12:07:08Z : No. of bitstreams: 1 000807370.pdf: 2293849 bytes, checksum: d68b7cab07938392e6c6fbc74359add9 (MD5) / As exigências e a competitividade atual levam, cada vez mais, à busca por soluções mais baratas e eficazes, para qualquer segmento de mercado. Com isso, o ramo aeronáutico tem procurado por ferramentas que possibilitem o mais alto rendimento possível aliado à redução de custos. Este trabalho de furação em placas de titânio 6Al4V tem origem em função da comunalidade de uso deste material nas indústrias, por manter alta resistência mecânica e a altas temperaturas. As ferramentas escolhidas foram brocas de metal duro e brocas de aço rápido sinterizado objetivando um estudo comparativo entre estas, nas mais variadas condições de corte, desde a refrigeração em abundância com utilização de óleo solúvel, passando pela usinagem à seco e finalizando com o sistema da Mínima Quantidade de Lubrificação (MQL) com óleo de corte puro. Os parâmetros de corte adotados foram conforme literatura técnica, para brocas de metal duro, utilizou-se velocidade de corte de 28 m/min, avanço total de 72 m/min e rotação de 2123 RPM e para as brocas de aço rápido sinterizado, velocidade de corte de 11 m/min, avanço total de 29 mm/min e rotação de 876 RPM. Anterior ao inicio dos testes, foi aplicado a ferramenta de Análise do Modo e Efeito de Falha a fim de identificar e prevenir possíveis discrepâncias na execução do processo de furação. A usinagem ocorreu em passes de 8mm de profundidade com interrupção a cada 200mm a 250mm para recolhimento de amostra de cavaco e avaliação parcial dos diversos possíveis desgastes nas ferramentas. Os parâmetros iniciais de finalização de cada broca foram estabelecidos com desgaste de 0,1mm ou tolerância de furos finais acima de H12. Os testes foram repetidos para ambas as brocas sempre em condições idênticas a fim de permitir uma comparação de resultados entre as ferramentas, geração ... (Resumo completo, clicar acesso eletrônico abaixo) / The current requirements and the competitiveness lead, increasingly, to the search for cheaper and more effective solutions, to any segment of the market.Thus the aeronautics the aviation industry has been searching for tools that allow the highest possible income combined with the cost reduction.. This work of drilling in 6Al4V titanium plates originates due to the commonality of use of this material in industries, for maintaining high mechanical strength and high temperatures. The tools chosen were carbide drills and drills of sintered high speed steel aiming at a comparative study between these, in the most varied cutting conditions, since refrigeration in abundance with use of oil soluble, through dry machining and finishing with the system of Minimal Quantity of Lubrication with neat cutting oil. The cutting parameters were adopted as technical literature, for carbide drills, used cutting speed of 28 m/min, total advance of 72 m/min and 2123 RPM rotation and sintered high speed steel drills, cutting speed of 11 m/min, total advance of 29 mm/min and 876 RPM rotation. Prior to the start of the tests, was applied to the analysis tool mode and effect of failure in order to identify and prevent possible discrepancies in the execution of the drilling process. The machining occurred in 8 mm deep steps with interruption every 200 mm to 250 mm for chip sample and partial evaluation of the various possible wear on tools. The initial parameters of completion of each drill were set with 0,1mm wear or tolerance of final holes above H12. The tests were repeated for both drills always in identical terms in order to allow a comparison of results between the tools, chip generation and final diameter. The diameters were measured with standard pins every 20 holes where, even after intense damage, there was no pre-established dimensional limits variation i.e. ... (Complete Abstract click electronic access below)
137

How Cyanobacteria Bore

January 2010 (has links)
abstract: Some cyanobacteria, referred to as boring or euendolithic, are capable of excavating tunnels into calcareous substrates, both mineral and biogenic. The erosive activity of these cyanobacteria results in the destruction of coastal limestones and dead corals, the reworking of carbonate sands, and the cementation of microbialites. They thus link the biological and mineral parts of the global carbon cycle directly. They are also relevant for marine aquaculture as pests of mollusk populations. In spite of their importance, the mechanism by which these cyanobacteria bore remains unknown. In fact, boring by phototrophs is geochemically paradoxical, in that they should promote precipitation of carbonates, not dissolution. To approach this paradox experimentally, I developed an empirical model based on a newly isolated euendolith, which I characterized physiologically, ultrastructurally and phylogenetically (Mastigocoleus testarum BC008); it bores on pure calcite in the laboratory under controlled conditions. Mechanistic hypotheses suggesting the aid of accompanying heterotrophic bacteria, or the spatial/temporal separation of photosynthesis and boring could be readily rejected. Real-time Ca2+ mapping by laser scanning confocal microscopy of boring BC008 cells showed that boring resulted in undersaturation at the boring front and supersaturation in and around boreholes. This is consistent with a process of uptake of Ca2+ from the boring front, trans-cellular mobilization, and extrusion at the distal end of the filaments (borehole entrance). Ca2+ disequilibrium could be inhibited by ceasing illumination, preventing ATP generation, and, more specifically, by blocking P-type Ca2+ ATPase transporters. This demonstrates that BC008 bores by promoting calcite dissolution locally at the boring front through Ca2+ uptake, an unprecedented capacity among living organisms. Parallel studies using mixed microbial assemblages of euendoliths boring into Caribbean, Mediterranean, North and South Pacific marine carbonates, demonstrate that the mechanism operating in BC008 is widespread, but perhaps not universal. / Dissertation/Thesis / Ph.D. Microbiology 2010
138

Aspectos da furação do titânio 6Al4V com broca de aço rápido sinterizado e broca de metal duro /

Allegrini, Alex. January 2014 (has links)
Orientador: Marcos Valério Ribeiro / Banca: José Vitor Candido de Souza / Banca: Alessandro Roger Rodrigues / Resumo: As exigências e a competitividade atual levam, cada vez mais, à busca por soluções mais baratas e eficazes, para qualquer segmento de mercado. Com isso, o ramo aeronáutico tem procurado por ferramentas que possibilitem o mais alto rendimento possível aliado à redução de custos. Este trabalho de furação em placas de titânio 6Al4V tem origem em função da comunalidade de uso deste material nas indústrias, por manter alta resistência mecânica e a altas temperaturas. As ferramentas escolhidas foram brocas de metal duro e brocas de aço rápido sinterizado objetivando um estudo comparativo entre estas, nas mais variadas condições de corte, desde a refrigeração em abundância com utilização de óleo solúvel, passando pela usinagem à seco e finalizando com o sistema da Mínima Quantidade de Lubrificação (MQL) com óleo de corte puro. Os parâmetros de corte adotados foram conforme literatura técnica, para brocas de metal duro, utilizou-se velocidade de corte de 28 m/min, avanço total de 72 m/min e rotação de 2123 RPM e para as brocas de aço rápido sinterizado, velocidade de corte de 11 m/min, avanço total de 29 mm/min e rotação de 876 RPM. Anterior ao inicio dos testes, foi aplicado a ferramenta de Análise do Modo e Efeito de Falha a fim de identificar e prevenir possíveis discrepâncias na execução do processo de furação. A usinagem ocorreu em passes de 8mm de profundidade com interrupção a cada 200mm a 250mm para recolhimento de amostra de cavaco e avaliação parcial dos diversos possíveis desgastes nas ferramentas. Os parâmetros iniciais de finalização de cada broca foram estabelecidos com desgaste de 0,1mm ou tolerância de furos finais acima de H12. Os testes foram repetidos para ambas as brocas sempre em condições idênticas a fim de permitir uma comparação de resultados entre as ferramentas, geração ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The current requirements and the competitiveness lead, increasingly, to the search for cheaper and more effective solutions, to any segment of the market.Thus the aeronautics the aviation industry has been searching for tools that allow the highest possible income combined with the cost reduction.. This work of drilling in 6Al4V titanium plates originates due to the commonality of use of this material in industries, for maintaining high mechanical strength and high temperatures. The tools chosen were carbide drills and drills of sintered high speed steel aiming at a comparative study between these, in the most varied cutting conditions, since refrigeration in abundance with use of oil soluble, through dry machining and finishing with the system of Minimal Quantity of Lubrication with neat cutting oil. The cutting parameters were adopted as technical literature, for carbide drills, used cutting speed of 28 m/min, total advance of 72 m/min and 2123 RPM rotation and sintered high speed steel drills, cutting speed of 11 m/min, total advance of 29 mm/min and 876 RPM rotation. Prior to the start of the tests, was applied to the analysis tool mode and effect of failure in order to identify and prevent possible discrepancies in the execution of the drilling process. The machining occurred in 8 mm deep steps with interruption every 200 mm to 250 mm for chip sample and partial evaluation of the various possible wear on tools. The initial parameters of completion of each drill were set with 0,1mm wear or tolerance of final holes above H12. The tests were repeated for both drills always in identical terms in order to allow a comparison of results between the tools, chip generation and final diameter. The diameters were measured with standard pins every 20 holes where, even after intense damage, there was no pre-established dimensional limits variation i.e. ... (Complete Abstract click electronic access below) / Mestre
139

Analise radiografica da região de furca, apos a confecção e contaminação de trepanações experimentais em dentes de cães seladas com diferentes materiais

Rodrigues, Ronaldo Rogerio 13 December 2000 (has links)
Orientador: Fabricio Batista Teixeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-07-27T10:31:53Z (GMT). No. of bitstreams: 1 Rodrigues_RonaldoRogerio_M.pdf: 2173324 bytes, checksum: 4537dbe5cef51b274531cf00699f4749 (MD5) Previous issue date: 2000 / Resumo: O objetivo deste trabalho foi analisar radiograficamente a perda óssea na região de furca, em dentes de cães, intencionalmente perfurados e contaminados pela exposição ao meio oral, frente ao emprego de vários materiais seladores da cavidade de acesso coronário. Foram utilizados 6 cães adultos, pesando entre 9 e 15Kg, fêmeas e de raça indefinida. Perfurações foram produzidas na região de furca dos 2°, 3° e 4° pré-molares inferiores direitos e esquerdos, permanecendo expostas à cavidade oral por um período de 30 dias. Após este intervalo de tempo, tendo constatado a formação das lesões de furca através de radiografias periapicais, os dentes foram limpos e tratados de acordo com a divisão dos grupos experimentais. As perfurações dos 2°, 3° e 4° pré-molares foram preenchidas com sulfato de cálcio hemidratado e seladas com guta-percha, IRM e resina Z-100, respectivamente, sendo descontaminadas com c1orexidina gel a 2% somente os dentes do lado direito. Radiografias padronizadas foram realizadas no início do experimento, 3 O dias após a exposição das perfurações à cavidade oral e 180 dias após o emprego dos materiais seladores. As imagens foram transportadas para o computador e mensuradas as áreas de perda óssea utilizando o programa "ImageLab". Os resultados foram analisados estatisticamente e as imagens demonstraram menor perda de estrutura óssea quando as perfurações foram seladas com resina Z-100, ao serem comparadas com IRM e guta-percha, demonstrando menor perda óssea com a utilização da c1orexidina gel a 2% para a descontaminação / Abstract: The objective of this work was to analysis radiographically the bony loss in the furcation region, in dog's teeth, intentionally perforated and contaminated with oral fluids, about the employment of several sealer materiaIs. It was utilized 6 adult dogs, weighing from 9 to 15 kilograms, females and the indefmite race. Perforations were produced in the furcation's region from the 2°, 3°, and 4° inferior right and left premolars, and they stayed exposed to the oral cavity for a period of 30 days. Afterwards this interview of time, was found the formation of furcation' s lesions by periapical radiography, the teeth were cleaned and treated in accord to the experimental groups division. The perforation of the 2°, 3°, and 4° premolars were fulfilled with hemihydrated calcium sulfate and sealed with gutta-percha, IRM and Z-100 resin, respectively, and just the right side teeth's perforation were decontaminated with 2% gel chlorhexidine. Padronized radiographic were made in the beginning of the experiment, 30 days after the exposition of the perforations to the oral cavity and 180 days after the employment of the sealer materiaIs. The images were transported to the computer and the areas of the bony loss were measured utilizing the "ImageLab" programo The results were analyzed statically andthe images demonstrated minor loss of bony structure when the perforation were sealed with Z-100 resin, in comparation to IRM and gutta-percha, demonstrating minor bony loss with the utilization of 2% gel chlorhexidine for the decontamination / Mestrado / Endodontia / Mestre em Clínica Odontológica
140

Túneis escavados em solo por máquina tuneladora: conceituação, comportamento do maciço e modelagem numérica. / Tunnels excavated in soil by tunneling machine: conceptualization, ground behavior and numerical modeling.

Gustavo Aguiar 06 April 2017 (has links)
Este trabalho apresenta um estudo a respeito do comportamento do solo durante a escavação de um túnel, com foco na metodologia de escavação mecanizada. São abordadas diretrizes para a modelagem numérica de túneis com o emprego de diferentes métodos de cálculo, distintos modelos constitutivos para representação do comportamento do solo e duas maneiras de se representar o revestimento da escavação. Alguns conceitos fundamentais relacionados a escavações de túneis de grande diâmetro em solo com o emprego de máquinas tuneladoras são descritos, como os tipos de máquinas existentes (com ênfase nas máquinas do tipo EPB - Earth Pressure Balance), princípios de funcionamento e modos de operação, além de uma comparação deste método com a metodologia sequêncial tradicional. É realizada uma revisão bibliográfica sobre distintos métodos de cálculo para estimar a estabilidade de uma escavação, a previsão da deformação no maciço e os esforços atuantes no revestimento do túnel. O trabalho também apresenta uma revisão de publicações recentes a respeito da modelagem numérica de túneis escavados mecanicamente, destacando algumas diferenças em relação à metodologia sequencial. Uma das diferenças é com relação à simulação do revestimento do túnel, com a possibilidade de se considerar as propriedades das juntas dos anéis. Outro ponto distinto é o método de cálculo empregado, levando em conta na simulação aspectos específicos da escavação mecanizada, como pressão de frente aplicada, vazio anelar e injeção de grout. É feita uma breve introdução e são apresentados os conceitos básicos de dois modelos constitutivos do solo: o modelo elastoplástico perfeito conhecido como Mohr-Coulomb e o modelo elastoplástico com endurecimento Hardening Soil. Utilizando alguns dos conceitos estudados na revisão bibliográfica, são realizadas análises numéricas bidimensionais retroanalisando um caso real de escavação com tuneladora. Foi utilizado o programa de elementos finitos Plaxis para realizar comparações entre os métodos de cálculo do alívio de tensões e da contração, além da simulação do revestimento com ou sem a consideração das juntas. Por fim é feita uma análise crítica dos resultados obtidos nas diferentes modelagens numéricas. / This research presents a study about the soil behavior during the excavation of a tunnel, focusing on the mechanized excavation methodology. Guidelines for the numerical modeling of tunnels with the use of different calculation methods, distinct constitutive models to characterize the soil behavior and two ways of representing the lining of the excavation are addressed. Relevant aspects regarding excavations of large diameter tunnels in soil with the use of TBM (Tunnel Boring Machine) are presented, like types of machines, with the focus on the Earth Pressure Balance (EPB) machines, fundamental concepts of the methodology and operation modes, besides a comparison of this method with the traditional sequential methodology. A literature review on different methods of calculation to estimate the excavation stability, the prediction of ground deformation and the efforts acting in the tunnel lining is made. The research also presents a review of recent publications regarding numerical modeling of mechanically excavated tunnels, highlighting some differences with the sequential method. One of these differences is related to the simulation of the tunnel lining, with the possibility of considering the properties of the ring joints. Another different point is the calculation method employed, considering in the simulation specific aspects of mechanized excavation, as front pressure applied, ring void and grout injection. A brief introduction is made about constitutive models to represent the soil behavior and the basic concepts of two constitutive soil models are presented: Mohr-Coulomb and Hardening Soil. Using some of the concepts studied in the literature review, it is performed two-dimensional numerical analysis with a back-analysis of a real case, using the finite element model program Plaxis, comparing the calculation methods of stress relieving and contraction, as well as the tunnel lining simulation with or without consideration of the joints. Finally, it is made a critical analysis of the results of the numerical simulations.

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