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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.
11

[pt] ALGORITMO PARA MEDIR DESLOCAMENTOS EM GRANDES ESTRUTURAS A PARTIR DE SINAIS ACELEROMÉTRICOS / [en] METHOD TO DETERMINE DISPLACEMENTS FROM ACCELEROMETER MEASUREMENTS IN LARGE STRUCTURES

JOSE GERALDO TELLES RIBEIRO 19 October 2012 (has links)
[pt] Em estudos de integridade estrutural devem-se realizar medições de deslocamentos, pois estes são diretamente relacionados aas deformações. Contudo, nos casos em que este estudo é realizado em grandes estruturas, como pontes e estádios, torna-se difícil realizar esta medição com os transdutores disponíveis, tais como medidores de deslocamento resistivos e LVDT’s, pois há necessidade de se ter uma referência fixa perto do ponto onde se deseja realizar a medição. Existem muitos transdutores novos que utilizam tecnologia laser para a realização destas medições, contudo, este tipo de transdutor é ainda relativamente caro. Outra forma de se obter deslocamentos é através da integração dupla de sinais acelerométricos, contudo os integradores duplos analógicos comerciais disponíveis apresentam muitos problemas relacionados à sua Resposta Dinâmica e não são uma boa solução. Dessa forma, nesta tese é proposta uma forma de se realizar esta integração dupla de forma digital,obtendo-se então um sistema de medição de deslocamentos que utiliza acelerômetros. / [en] The measurement of displacements is very important of structural integrity, because they are directly related to the deformations. However, when the measurements are supposed to be made in huge structures, as bridges and stadiums, it becomes very difficult, because the available transducers, like LVDT’s, need to be fastened to a fixed reference. There are many new transducers the use laser to make these measurements, but, this kind of transducer are still expensive. Another form to measure displacements is through the double integration of accelerometer signals, however the analog double irregrators available presents many problems related to its Dynamic Response and can’t be used for this purpose. In this thesis it is proposed a digital way of making this double integration, allowing us to obtain a displacement measurement system that uses accelerometers.
12

Nature and Mechanisms of Displacements at Wolf Creek Dam, Jamestown, Kentucky

Wiles, Sarah Grace 04 December 2013 (has links)
No description available.
13

The Accuracy of Measuring Lumbar Vertebral Displacements Using a Dynamic MRI Sequence

Goubeaux, Craig A. January 2017 (has links)
No description available.
14

Characterisation of point defects in SiC by microscopic optical spectroscopy

Evans, Geraint Andrew January 2001 (has links)
No description available.
15

Verschiebungsmuster in Böschungen während Aushubvorgängen / Displacement patterns in slopes during excavation processes

Nitzsche, Kornelia 06 December 2016 (has links) (PDF)
After the excavation of a cut slope ongoing deformations on the slope surface can often be measured. These deformations can be induced due to various processes and can also be used as an indicator of slope stability. If the reasons for the deformations are known, selective stabilization methods can help to decelerate, or stop, the movements. The potential for the recognition of displacement patterns in excavated slopes is studied in this dissertation. In the laboratory, the analysis of displacement patterns due to various processes is difficult as identical initial test conditions can hardly be reproduced. Furthermore, measurements of displacements can only be conducted to a limited degree. Therefore, numerical calculations using the finite element method were applied to simulate excavation processes and analyse the displacements. In addition, a suitable mathematical model has to be used to represent the stress-strain behaviour during the unloading process. Three different advanced constitutive soil models were chosen to calculate an excavation process of an idealized slope assuming drained conditions: - elasto-plastic Modified-Cam-Clay model - rate-independent hypoplastic model according to Masin - rate-dependent visco-hypoplastic model according to Niemunis Before conducting the excavation simulation, the soil parameters of the constitutive models were calibrated by means of numerical element tests, depicting the stress paths of conventional laboratory tests. Within the literature, those conventional laboratory tests are recommended for the determination of parameters for the constitutive models. A parameter set for the visco-hypoplastic model was chosen from literature. The parameters were adapted for the remaining models. Thus, all three models predicted approximately the same stress-strain behaviour during conventional laboratory tests. Despite the correlations during the element tests, the constitutive models predicted different displacements during the calculation of the excavation of an idealized slope under drained conditions. Thereupon, load-controlled triaxial compression tests were conducted reproducing the characteristic stress paths during an excavation process. At the same time, numerical calculations were carried out to reproduce the triaxial compression tests, and the measured and calculated displacement behaviour was compared. Different processes such as pure unloading due to excavation, excavation in overconsolidated soil, excavation coupled with consolidation, excavation coupled with previous ground water lowering and consolidation as well as the influence of creep effects were considered in the analysis of the displacement patterns during an excavation. It can be stated that the evaluation of displacements and changes in displacements in a single point on the slope surface cannot provide sufficient information about a certain physical process. Only the combination of displacement paths at different survey points will lead to a reliable conclusion. Thus, representative displacement patterns for different processes are recognizable during and after the excavation, which can be used for the identification. During the numerical simulation of an in-situ model test, where a slope was brought to failure by excavation, the calculated displacements were analysed for identifiable displacement patterns. It can be stated that despite different slope systems, consistencies were found within characteristic survey points. These points can be used to identify patterns within the displacement contours.
16

[en] REFUGE, ADDRESS UNFINISHED CREATURE: RECOGNITION AND RIGHTS OF DISPLACED PEOPLE / [pt] REFÚGIO, A MORADA DA CRIATURA INACABADA: RECONHECIMENTO E DIREITOS DOS POVOS DESLOCADOS

MARIA LEILA SALES 19 January 2015 (has links)
[pt] O presente texto tem como objetivo relatar o universo do refúgio na cidade do Rio de Janeiro; analisando os fatores socioeconômicos e culturais que permeiam o movimento de entrada e permanência dessa população no município. Aborda principalmente questões relativas aos direitos humanos, problematizando ao mesmo tempo, sua existência por vezes abstrata, fator que dificulta a inserção dos deslocados na sociedade, aumentando com isso, as fraturas existentes entre eles e o Estado-Nação. Fez-se uma tentativa no sentido de compreender quais os lugares ocupados pelos deslocados nessa nova territorialidade em que se privilegia o fim das limitações comerciais e econômicas, garantindo livre fluxo de capitais em detrimento do próprio fluxo da vida humana. / [en] This text is intended to provide a report on the refuges universe in Rio de Janeiro by analyzing social, economic and cultural aspects which permeate the motion and permanence of this population. It approaches questions concerning the human rights, arguing at the same time its own existence, sometimes abstract, which makes difficult the social insertion of the refugees and increases the rupture between this social group and the state-nation. There was an attempt to understand the places occupied by the refugees in this new territoriality where the end of commercial and economic limitations and the free flow of capital is encouraged rather of the flow of human life.
17

[en] TODAY I FEEL AFRICAN: IDENTITIES (RE)CONSTRUCTION PROCESSES IN A GROUP OF CAPE VERDEAN STUDENTS IN RIO DE JANEIRO / [pt] HOJE EU ME SINTO AFRICANA: PROCESSOS DE (RE)CONSTRUÇÃO DE IDENTIDADES EM UM GRUPO DE ESTUDANTES CABO-VERDIANOS NO RIO DE JANEIRO

OLIVIA NOGUEIRA HIRSCH 02 June 2008 (has links)
[pt] A pesquisa busca compreender os processos de (re)construção identitária vividos por um grupo de estudantes cabo-verdianos no Rio de Janeiro. Identificados majoritariamente como negros e mulatos pelos brasileiros, esses estudantes vêm de uma sociedade que atribui à mestiçagem a especificidade da identidade nacional. Esse discurso, construído por uma elite que muito se apropriou das idéias de Gilberto Freyre, buscava diferenciar os cabo-verdianos das populações das demais colônias portuguesas na África, garantindo ao ilhéu o posto de segundo colonizador. No Rio de Janeiro, porém, foi possível constatar que a maioria desses jovens construiu um olhar mais crítico em relação à mestiçagem. Esse processo foi acompanhado de uma valorização de uma identidade afro-referenciada, possivelmente por influência do intenso debate sobre a implementação de políticas de identidade no Brasil. Mas as transformações vividas pelos estudantes cabo-verdianos não se limitam à identidade étnica. Provenientes de um país onde há mais habitantes fora do que dentro de seus limites geográficos, estudar no exterior significa para esses jovens não apenas estar em vias de conformar a futura elite intelectual do arquipélago, mas também construir-se como cabo-verdiano, na medida em que a adaptação a outras culturas é percebida como uma especialidade nacional. / [en] The research focuses on the identities (re)construction processes experienced by a group of Cape Verdean students in Rio de Janeiro. Mainly identified by Brazilians as blacks and mulattoes, those students come from a society where miscegenation is seen as a national identity specificity. This speech, constructed by an elite that eagerly adopted Gilberto Freyre`s ideas, intended to differentiate the Cape Verdeans from the populations of the other Portuguese colonies in Africa granting the islanders a second colonizer status. In Rio de Janeiro, however, it was possible to verify that the majority of those youngsters had developed a more critical view regarding the idea of miscegenation. This process occurred simultaneously to the valorization of an afro identity, possibly influenced by the intense debate regarding the implementation of identities politics in Brazil. Nevertheless, the transformations experimented by the Cape Verdean students can not be reduced to the ones regarding the ethnic identity. Coming from a country where there are more inhabitants outside than inside their geographical borders, to study abroad means for those youngsters not only to be in the path to become part of the archipelago`s future intellectual elite, but also to construct themselves as Cape Verdeans, since adaptation to other cultures is perceived as a national specialty.
18

Avaliação da rigidez rotacional em estruturas planas de madeira concebidas por elementos unidimensionais com dois parafusos por nó / Evaluation of the rigidity rotational in plane structures of wood become pregnant by one-dimensional elements with two screws by node

Christoforo, André Luis 27 June 2003 (has links)
Neste trabalho, é desenvolvido um programa através do método dos deslocamentos, em que o mesmo leva em consideração a influência do efeito da semi-rigidez rotacional nas ligações formadas por dois parafusos sobre o comportamento mecânico da estrutura. Esta configuração de parafusos é devidamente escolhida em função de sua corrente aplicação em estruturas de madeira, principalmente em estruturas auxiliares ou de cobertura. Vários exemplos de estruturas típicas de cobertura são executados considerando-se as três formas que o presente programa analisa, evidenciando-se a importância do comportamento semi-rígido sobre as ligações. / In this work, a program is developed through the method of the displacements, in that the same get the worst of the influence of the effect of semi-rigidity rotational in the connections formed by two screws about the mechanical behaviour of the structure. This configuration of screws is chosen properly in function of your current application in wood structures, mainly in auxiliary structures or of covering. Several examples of typical structures of covering are executed being considered the three analysis forms in that the present program executes, being evidenced the importance of the semi-rigid behaviour about the connections.
19

Contribuição ao estudo de estruturas de cabos para coberturas de grandes áreas livres, considerando as não linearidades física e geométrica / Contribution to the study of cable structures for large span roofs by considering material and geometric non-linearity

Aguiar, Elizabeth Oshima de 01 October 1999 (has links)
A pesquisa foi desenvolvida com a finalidade de se analisar o comportamento elástico e inelástico de estruturas de cabos, sob carregamento estático, pela técnica dos elementos finitos. Para a discretização das estruturas de cabos adotou-se um elemento retilíneo isoparamétrico, e na formulação dos princípios variacionais foram considerados a não linearidade física do material e a não linearidade geométrica, inerente às estruturas de cabos. Empregou-se o método incrementai-iterativo de Newton-Raphson para a resolução do sistema de equações não lineares. Alternativamente a solução foi obtida da minimização direta da função energia potencial total da estrutura de cabos, utilizando-se o método do Gradiente Conjugado. Vários exemplos de estruturas de cabos comumente empregadas em coberturas de grandes vãos foram estudados. Os resultados obtidos segundo os dois procedimentos foram analisados e a eficiência elos métodos foi comprovada. / The research was developed with the purpose of analyzing the elaslic and the inelaslic behaviour of cable slructures, under static load. The finite element method with straight isoparametric element was used. In the formulation of the variational principles, the material and the geometric non-linearity were considered. The Newton-Raphson method was used to resolve the non-linear equations system. Alternatively the solution was obtained of the direct minimization of the total potential energy of the cable structure; in this case using the Conjugated Gradient Method. Several examples of cable structures, commonly employed in roofs of large spaces were studied. The results were obtained according to both processes and the efficiency of the methods was verified.
20

Análise de edifícios altos submetidos a terremotos pela técnica do meio contínuo / Analysis of tall buildings subject to earthquakes using the continuous medium technique

Espezúa Llerena, César Alfredo 27 August 2009 (has links)
Nesta dissertação emprega-se um método simplificado de análise elástica baseado na técnica do meio contínuo para edifícios altos submetidos a terremoto formados por painéis paredes, pórticos e núcleos de seção aberta de parede delgada. Na ligação dos diferentes painéis, supõe-se que existe uma considerável quantidade de diafragmas horizontais rígidos em seu próprio plano, distribuídos continuamente ao longo da vertical 0z. Levando-se em conta a equação constitutiva dos painéis individuais pode-se obter a solução de analise estrutural para o edifício mediante equações diferenciais acopladas para deslocamento e rotações ao longo do eixo vertical do edifício. Com base nesses resultados, todos os esforços internos podem, então, ser obtidos. O método de análise proposto oferece um simples e rápido meio de obtenção da deformada e das forças internas dos diferentes painéis do edifício alto em fases iniciais do projeto. A utilidade e a aproximação do método são examinadas mediante exemplos numéricos, sendo a solução aproximada comparada com aquela obtida com o emprego do método de elementos finitos elaborado pelo programa SAP2000. / This work presents a simplified method of elastic analysis based on the continuous medium technique for tall building structures formed by shear wall panels, frames and core thin walled sections. In order to connect the various panels, it is assumed that there exist a considerable amount of rigid diaphragms continuously distributed along the vertical 0z. The building is subject to lateral earthquake load. Taking into account the constitutive equation of the individual panel, one can achieve a solution through coupled differential equations for displacement and rotation of the building. Based on that, all of the internal forces can be obtained. The analysis is extended to structures formed by singular panel configuration. The proposed method offers a relatively simple and rapid way to obtain the displacements and internal forces of different structural systems of tall buildings, especially indicated for preliminary stages of calculation. The usefulness of the approach and method are illustrated by numerical examples, where the approximated solution is compared with that obtained by finite element calculations.

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