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Uso das imagens SAR R99B para mapeamento geomorfológico do furo do Ariaú no município de Iranduba - AM / The use of pictures of the Synthetic Aperture Radar (SAR) R99B for geomorphological mapping along the \"Furo do Ariaú\" in the municipality of Iranduba - AMPinto, Willer Hermeto Almeida 29 July 2013 (has links)
O estudo das formas do relevo terrestre teve um avanço expressivo com a utilização das modernas ferramentas de sensoriamento remoto. Na região Amazônica, devido à vasta cobertura de nuvens, bruma e fumaça, quase que o ano inteiro, de certa forma, ocasiona dificuldade para levantamento com sensores ópticos. As melhores imagens para a região, portanto, são as imagens provenientes de radar, pois esse sistema tem a vantagem de adquirir imagens, independente, da presença de nuvens ou fumaça. Desta forma, este trabalho teve por objetivo principal o uso das imagens do Radar de Abertura Sintética (SAR) R99B para o mapeamento geomorfológico ao longo do furo do Ariaú no município de Iranduba. A escolha desta área se justifica por apresentar características naturais e socioeconômicas bem peculiares. Na questão natural, Iranduba está encravado entre os dois maiores caudal da região: rio Negro e Solimões/Amazonas e composto de um ambiente de terra firme e várzea. Na questão socioeconômica, é nesse município que se encontra, também, o maior polo oleiro do estado do Amazonas. A metodologia empregada neste trabalho foi baseada na adaptação dos métodos propostos por Lima (1995), composta de três fases: identificação, análise e interpretação. O método proposto permitiu a interpretação das feições geomorfológicas baseadas na textura das imagens SAR/R99B com múltiplas polarizações para as terras baixas com altitude não ultrapassando 100 m. A fim de buscar entender a dinâmica fluvial da área do Ariaú foi realizado trabalho de campo e levantamento pedológico. Como resultado desta pesquisa, obteve-se mapa da drenagem, mapa geomorfológico das feições fluviais e os principais nutrientes do solo na calha do Ariaú. As imagens do SAR mostraram-se eficientes para as diferentes feições geomorfológicas para o mapeamento de média escala, no entanto, a falta de imagens nos diversos períodos hidrológicos, seca, enchente, cheia e vazante, de certa forma, compromete um melhor entendimento do ambiente. Este trabalho, portanto, coloca-se como uma perspectiva para novas interpretações geomorfológicas dos ambientes fluviais nas áreas baixas da Amazônia. / The study of the forms of terrestrial landscape had a significant progress with the use of modern remote sensing tools. In the Amazon region, due to extensive cloud cover, haze and smoke, almost the entire year, somehow, causes difficulty imaging with optical sensors. The best images for the region, are the pictures from Radar because this system has the advantage of acquiring images, independent of the presence of clouds or smoke. Thus, this work aimed to use pictures of the Synthetic Aperture Radar (SAR) R99B for geomorphological mapping along the Furo do Ariaú in the municipality of Iranduba. The choice of this area is justified due to its peculiar natural and socioeconomic characteristics. In the natural matter, Iranduba is wedged between the two major flow region: Rio Negro and Solimões /Amazonas and composed of an environment of upland and floodplain. In the socioeconomic issue, it is in this city that lays the largest polo potter in the state of Amazonas. The methodology used in this study was based on the adaptation of the methods proposed by Lima (1995), composed of three phases: identification, analysis and interpretation. The proposed method allowed the interpretation of geomorphological features based on texture of SAR/R99B images with multiple polarizations to the lowlands to an altitude not exceeding 100m. In order to try to understand the dynamics of the Ariaú river area fieldwork and soil survey were conducted. As a result of this research a map was obtained, including the drainage map, geomorphological map of the river and the main nutrients in the soil trough Ariaú. The SAR images were effective for different geomorphological mapping to medium scale, however, the lack of pictures in different hydrological periods, drought, flooding and receding somewhat, compromises a better understanding of the environment. This work, therefore, arises as a prospect for new interpretations of fluvial geomorphic low-lying areas of the Amazon.
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Uso das imagens SAR R99B para mapeamento geomorfológico do furo do Ariaú no município de Iranduba - AM / The use of pictures of the Synthetic Aperture Radar (SAR) R99B for geomorphological mapping along the \"Furo do Ariaú\" in the municipality of Iranduba - AMWiller Hermeto Almeida Pinto 29 July 2013 (has links)
O estudo das formas do relevo terrestre teve um avanço expressivo com a utilização das modernas ferramentas de sensoriamento remoto. Na região Amazônica, devido à vasta cobertura de nuvens, bruma e fumaça, quase que o ano inteiro, de certa forma, ocasiona dificuldade para levantamento com sensores ópticos. As melhores imagens para a região, portanto, são as imagens provenientes de radar, pois esse sistema tem a vantagem de adquirir imagens, independente, da presença de nuvens ou fumaça. Desta forma, este trabalho teve por objetivo principal o uso das imagens do Radar de Abertura Sintética (SAR) R99B para o mapeamento geomorfológico ao longo do furo do Ariaú no município de Iranduba. A escolha desta área se justifica por apresentar características naturais e socioeconômicas bem peculiares. Na questão natural, Iranduba está encravado entre os dois maiores caudal da região: rio Negro e Solimões/Amazonas e composto de um ambiente de terra firme e várzea. Na questão socioeconômica, é nesse município que se encontra, também, o maior polo oleiro do estado do Amazonas. A metodologia empregada neste trabalho foi baseada na adaptação dos métodos propostos por Lima (1995), composta de três fases: identificação, análise e interpretação. O método proposto permitiu a interpretação das feições geomorfológicas baseadas na textura das imagens SAR/R99B com múltiplas polarizações para as terras baixas com altitude não ultrapassando 100 m. A fim de buscar entender a dinâmica fluvial da área do Ariaú foi realizado trabalho de campo e levantamento pedológico. Como resultado desta pesquisa, obteve-se mapa da drenagem, mapa geomorfológico das feições fluviais e os principais nutrientes do solo na calha do Ariaú. As imagens do SAR mostraram-se eficientes para as diferentes feições geomorfológicas para o mapeamento de média escala, no entanto, a falta de imagens nos diversos períodos hidrológicos, seca, enchente, cheia e vazante, de certa forma, compromete um melhor entendimento do ambiente. Este trabalho, portanto, coloca-se como uma perspectiva para novas interpretações geomorfológicas dos ambientes fluviais nas áreas baixas da Amazônia. / The study of the forms of terrestrial landscape had a significant progress with the use of modern remote sensing tools. In the Amazon region, due to extensive cloud cover, haze and smoke, almost the entire year, somehow, causes difficulty imaging with optical sensors. The best images for the region, are the pictures from Radar because this system has the advantage of acquiring images, independent of the presence of clouds or smoke. Thus, this work aimed to use pictures of the Synthetic Aperture Radar (SAR) R99B for geomorphological mapping along the Furo do Ariaú in the municipality of Iranduba. The choice of this area is justified due to its peculiar natural and socioeconomic characteristics. In the natural matter, Iranduba is wedged between the two major flow region: Rio Negro and Solimões /Amazonas and composed of an environment of upland and floodplain. In the socioeconomic issue, it is in this city that lays the largest polo potter in the state of Amazonas. The methodology used in this study was based on the adaptation of the methods proposed by Lima (1995), composed of three phases: identification, analysis and interpretation. The proposed method allowed the interpretation of geomorphological features based on texture of SAR/R99B images with multiple polarizations to the lowlands to an altitude not exceeding 100m. In order to try to understand the dynamics of the Ariaú river area fieldwork and soil survey were conducted. As a result of this research a map was obtained, including the drainage map, geomorphological map of the river and the main nutrients in the soil trough Ariaú. The SAR images were effective for different geomorphological mapping to medium scale, however, the lack of pictures in different hydrological periods, drought, flooding and receding somewhat, compromises a better understanding of the environment. This work, therefore, arises as a prospect for new interpretations of fluvial geomorphic low-lying areas of the Amazon.
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Infra-red vision in ferrets (Mustela furo)Newbold, Haylie Goldene January 2007 (has links)
Ferrets are labelled Unwanted Organisms under the Biosecurity Act (1993) due to their predation on New Zealand's native protected species and their status as potential vectors of Bovine Tuberculosis. There was suspicion that ferrets could detect the infrared light-emitting equipment used to monitor predator and prey behaviour. A two-alternative forced-choice operant procedure was used to test whether five pigmented male ferrets could detect infrared (870 and 920 nm) light. First, the ferrets were taught to press a lever under a lit visible (white) light emitting diode (LED) for food rewards. After up to 101 40-minute sessions, each ferret could lever press under the lit-light at or above the pass criteria of 75% responses over four consecutive (or five out of six) sessions. The same ferrets were then tested for stimulus generalisation over different stimulus properties by changing the wavelength/colour and intensity of the lit-light. The overall mean accuracy of each ferret's response to each coloured light varied between 92% and 84%. When a red light was systematically dimmed to halve the intensity nine times, all five ferrets still met the set pass criteria with overall accuracies of between 88% and 78%. This indicated that changing the properties of the light stimuli would not disrupt the ferrets' abilities to perform the learned task. This test was a necessary prerequisite before changing the light stimuli to potentially invisible wavelengths in the infrared spectrum. The light stimulus was changed to a single infrared (870) nm LED. Two of five ferrets showed strong evidence (response accuracies of 77% 4 and 72% 2) and one ferret showed weak evidence (60% 3) that they could see the light at this wavelength. Extraneous cues such as ultrasound emitted at the onset of a stimulus light or a predictable schedule of reinforcement were eliminated as potential response cues. These tests helped to prove that the ferrets were using only the light stimulus to discriminate which stimulus was lit. It may be possible that at least some feral ferrets can detect the light produced from infrared monitoring equipment that emits light wavelengths at or below 870 nm. This has significant implications for conservation because infrared equipment is used by conservation agencies in New Zealand and overseas to monitor predator and prey behaviour in the wild. If the infrared lighting is detected by the subject being observed, then it may potentially influence the behaviour of the animal, or attract a predator towards threatened native species.
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Conception de ligands mixtes mélatoninergiques et sérotoninergiques à structure azaindolique et furopyridinique / Conception of new azaindolic and furopyridinic ligands with melatoninergic and serotoninergic activityCouhert, Audrey 19 February 2015 (has links)
La mélatonine est une neurohormone sécrétée en période nocturne dans la glande pinéale. Elle régule les rythmes biologiques et influe sur différents processus physiologiques. Son implication ainsi que celle de la sérotonine, un neurotransmetteur, dans certains troubles de l’humeur font des récepteurs associés à ces deux hormones (MT1, MT2 et 5-HT2C respectivement) des cibles innovantes pour le développement de nouveaux antidépresseurs. Dans le cadre de cette thèse, des ligands mixtes mélatoninergiques et sérotoninergiques en série 7-azaindolique ont été synthétisés et testés biologiquement. L’élaboration de dérivés furo[3,2-b]pyridiniques a permis d’évaluer le potentiel biologique de ce squelette original et de mettre au point une nouvelle méthode de synthèse de ce motif. Ces travaux ont également été l’occasion d’étudier l’influence sur l’affinité et l’activité mélatoninergiques de la présence de différents groupements aryles plus ou moins volumineux en position 2 du noyau. Le dernier objectif a consisté dans le développement d’une voie d’accès à des analogues furopyridiniques tricycliques. Le raisonnement méthodologique poursuivi réside dans la mise en place d’une séquence réactionnelle permettant d’accéder aux structures désirées via une procédure courte et efficace. / Melatonin is a neurohormone secreted in the pineal gland during dark phases. This regulator of the biological clock is thus involved in several physiological process. Melatonin and serotonin, a neurotransmitter, are involved in some mood disorders, leading to consider associated receptors (MT1, MT2 and 5-HT2C respectively) as innovative targets for the development of new antidepressant.During this PhD, some 7-azaindolic ligands with both melatoninergic and serotoninergic activity were synthesized and tested from a biological point of view.Elaboration of furo[3,2-b]pyridinic derivatives allow us to evaluate the biological potential of this scaffold and to develop a new synthetic pathway to this pattern. This work has been the opportunity to study the influence of bulky aryl groups at C2 position over affinity and activity of these molecules towards melatoninergic receptors.The last aim consisted in developing a new methodology to access tricyclic furopyridinic analogues with a short and efficient chemical sequence.
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[en] MEASUREMENT OF RESIDUAL STRESSES IN PIPES DRIVING THE DETERMINING OF EFFORTS IN BURIED PIPELINES / [pt] MEDIÇÃO DE TENSÕES RESIDUAIS EM TUBOS VISANDO A DETERMINAÇÃO DE ESFORÇOS EM DUTOS ENTERRADOSLEONARDO DANTAS RODRIGUES 30 August 2007 (has links)
[pt] O conhecimento dos esforços de flexão e normal provocados
por
movimentação de solo é importante para a análise de
integridade estrutural de
dutos. A existência de tensões residuais é um dos
principais obstáculos para
obtenção de resultados precisos na determinação de tais
esforços. Este trabalho
foi desenvolvido com o objetivo de analisar o
comportamento das tensões
residuais de fabricação em tubos ao longo de sua
circunferência e de seu
comprimento. Foram feitas medições de tensões residuais em
corpos de prova de
um tubo novo e de outros retirados de operação utilizando
a técnica de furo cego e
uma nova técnica de seccionamento. As medições foram
realizadas ao longo da
circunferência e em diferentes seções dos tubos. As
medições com a técnica de
seccionamento proposta, denominada técnica do furo
elíptico, mostraram-se
coerentes com as medições com o furo cego, principalmente
para as tensões
longitudinais. A partir dos resultados obtidos nos
experimentos realizados, foram
feitas recomendações e propostas metodologias para separar
as tensões residuais
de fabricação das tensões atuantes no duto em operação.
Para cada método
proposto foi feita uma simulação para avaliar seus erros.
As tensões residuais de
fabricação circunferenciais e longitudinais possuem
magnitudes consideráveis
(por vezes até próximas à resistência ao escoamento dos
tubos). Desprezá-las em
medições realizadas em campo, como é feito na maioria das
vezes para calcular
os esforços existentes, pode acarretar grandes erros na
determinação dos esforços
agindo sobre o duto. Os resultados das simulações
mostraram que, se as tensões
residuais forem baixas, os esforços de trabalho obtidos
desconsiderando-as são
próximos dos valores reais. No mais, os procedimentos
propostos para a
determinação dos esforços, mediante a separação das
tensões residuais existentes,
apresentaram erros menores ou, no mínimo, próximos aos
encontrados quando o
cálculo foi feito negligenciando-se as tensões residuais. / [en] The knowledge of the bending and axial efforts caused by
soil movement is
important for the structural integrity analysis of
pipelines. The existence of
residual stresses is one of the main obstacles for
obtaining good results in the
determination of such efforts. This work was developed to
analyze the behavior of
the residual stresses of manufacturing in pipes throughout
its circumference and
length. Measurements of residual stresses had been made in
samples of a new pipe
and others samplers removed from operation, using the hole
drilling technique and
a new sectioning technique. The measurements had been
carried throughout the
circumference and different sections of the pipes. The
measurements with the
sectioning technique proposed, called elliptical hole
technique, are coherent with
the measurements of the hole drilling technique, mainly
for the longitudinal
stresses. From the experimental results, recommendations
had been made and
methodologies had been proposed to separate the
manufacturing residual stresses
from the operating stresses in the pipelines. For each
method considered in this
work, a simulation was made to evaluate its errors. The
circumferential and
longitudinal residual stresses of manufacturing have
considerable magnitudes
(sometimes next to the yield strength of the pipes). Not
considering the residual
stresses in measurements carried through in situ to
calculate the existing loads, as
it is made most of the time, can cause significant errors
in the determination of the
efforts acting on the pipeline. The results of the
simulations had shown that, if the
residual stresses are low, the work loads obtained when
the residual stresses are
not considered are comparable with the correct loads. The
procedures proposed
for the determination of loads, considering the separation
of the existing residual
stresses, had presented smaller errors or closer to those
when the calculation was
made neglecting the residual stresses.
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Design and synthesis of pyrimido[4,5-b]indoles and furo[2,3-d]pyrimidines as single agents with combination chemotherapy potential or as inhibitors of tubulin or thymidylate synthaseDevambatla, Ravi Kumar Vyas 18 May 2016 (has links)
This dissertation describes an introduction, background and research progress in the areas of multitargeted single agents and tubulin inhibitors in cancer chemotherapy and selective Toxoplasma gondii TS inhibitors for the treatment of toxoplasmosis.<br>
Tubulin inhibitors are important antitumor agents that disrupt microtubule dynamics. Thymidylate synthase (TS) inhibitors prevent cell division by interfering with de novo thymidylate synthesis. Antiangiogenic agents target tumor angiogenesis crucial for tumor growth and metastasis. Under normal circumstances, angiogenesis is typically limited to tumor cells and is mediated by receptor tyrosine kinases (RTKs). Combination chemotherapies of RTK inhibitors with cytotoxic agents that target either TS or tubulin have shown significant promise and several preclinical and clinical studies with such combinations are in progress. Multitargeted single agents with dual antiangiogenic and cytotoxic mechanisms could avoid the major limitations associated with cancer chemotherapy: multidrug resistance and dose limiting toxicities. This dissertation focuses on the design and synthesis of pyrimido[4,5-b]indoles and furo[2,3-d]pyrimidines as potential single agents with dual antiangiogenic and cytotoxic activities. These efforts led to the identification of structural features that are necessary for inhibition of RTKs and/or tubulin polymerization. Novel synthetic strategies were developed for efficient synthesis of 2,4-diamino-5-thioaryl-pyrimido[4,5-b]indoles and 4-anilino-5-methyl-furo[2,3-d]pyrimidines.<br>
Taxanes and vinca alkaloids are widely used tubulin inhibitors in cancer chemotherapy. However, their clinical use is compromised by two major mechanisms of drug resistance: the overexpression of Pgp and bIII-tubulin. This dissertation describes the design and synthesis of pyrimido[4,5-b]indoles as tubulin inhibitors that circumvent Pgp and bIII-tubulin mediated resistance. This work identified the structural features crucial for tubulin inhibition for the pyrimido[4,5-b]indole scaffold.<br>
Infection by Toxoplasma gondii can lead to toxoplasmosis in immune compromised patients such as organ transplant, cancer and AIDS patients. Current therapy involving combination of sulfadiazine and pyrimethamine is limited by drug resistance and treatment failures. The thymidylate synthase‒dihydrofolate reductase enzyme is important for thymidylate synthesis in T. gondii, and hence can be targeted to treat T. gondii infection. TS is highly conserved across species and selectivity for tgTS over human TS is significantly more challenging. The present work provides an efficient synthesis of 2-diamino-4-oxo-5-thioaryl-pyrimido[4,5-b]indoles as selective tgTS inhibitors. / Mylan School of Pharmacy and the Graduate School of Pharmaceutical Sciences; / Medicinal Chemistry / PhD; / Dissertation;
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Synthèse et fonctionnalisation des furo[3,2-b]- et [2,3-c]pyridines par voie organométallique / Synthesis and functionalisation of furo [3,2-b]- et [2,3-c]pyridines by using an organometallic wayChartoire, Anthony 22 October 2010 (has links)
Le travail décrit dans ce mémoire concerne l'étude de la métallation régiosélective de deux bicycles fusionnés complexes : les furo[3,2-b]- et [2,3-c]pyridines. L'influence de la nature du système basique sur le cours de la réaction et sur la régiosélectivité de la lithiation a été étudiée avec différentes bases : n-BuLi, LTMP, LDA et [n-BuLi/LiDMAE]. D'un point de vue fondamental, cette étude nous a permis d'établir quelques règles pour la fonctionnalisation des hétérocycles complexes, ce qui nous a conduit à l'obtention efficace et rapide d'une vaste chimiothèque de furo[3,2-b]- et [2,3-c]pyridines polyfonctionnalisés et refonctionnalisables. Quelques composés préparés ont ainsi été mis en jeu dans des réactions de couplage catalysées par les métaux de transition (Pd, Ni). Les difficultés rencontrées au cours de ce travail nous ont permises de mettre en évidence une séquence de double fonctionnalisation des hétérocycles ?-déficients par une séquence "one-pot" combinant le piégeage d'un intermédiaire lithié par un électrophile et l'addition nucléophile d'une espèce réactive générée in-situ. Le développement de cette séquence nous a conduits à l'obtention directe de pyrazines, pyridines et furo[3,2-b]pyridines disubstituées / The work described in this PhD thesis concerns a regioselective metalation study of two fused heterocycles : the furo[3,2-b]- et [2,3-c]pyridines. The influence of the lithiated agent on the reaction course and on the selectivity of the lithiation has been studied with several bases : n-BuLi, LTMP, LDA and [n-BuLi/LiDMAE]. From a fundamental point of view, this study allowed us to establish some rules concerning the functionalisation of fused heterocycles, and then, a chemical library of polyfunctionalised furo[3,2-b]- and [2,3-c]pyridines has been designed. Some of the compounds obtained in this way were engaged in metallo-catalysed coupling reactions. The difficulties we met during this work allowed us to discover a double functionalisation sequence of ?-deficient heterocycles via a cascade process combining the trapping of lithiated intermediates and the nucleophilic addition of some in-situ released species. The development of this sequence afforded direct access to difunctionalised pyrazines, pyridines and furo[3,2-b]pyridines
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Inference on the host status of feral ferrets (Mustela furo) in New Zealand for Mycobacterium bovis infectionCaley, Peter, n/a January 2001 (has links)
This thesis is about making inference on the host status of feral ferrets in New
Zealand for Mycobacterium bovis, the aetiological agent of bovine tuberculosis. The
central question addressed is whether the rate of intra-specific transmission of M. bovis
among ferrets is sufficient for the disease to persist in ferret populations in the absence
of external, non-ferret sources of infection (inter-specific transmission). The question is
tackled in three parts�firstly using model selection to identify suitable models for
estimating the force of M. bovis infection in ferret populations; secondly applying
statistical hypothesis testing to the results of planned manipulative field experiments to
test the relationship between M. bovis infection in brushtail possums and that in ferrets;
and thirdly using modelling to estimate intra-specific disease transmission rates and the
basic reproductive rate (Ro) of M. bovis infection in ferrets.
The model selection approach clearly identified the hypothesis of oral infection
related to diet was, as modelled by a constant force of infection from the age of
weaning, the best approximation of how M. bovis infection was transmitted to ferrets.
No other form of transmission (e.g., during fighting, mating, or routine social
interaction) was supported in comparison. The force of infection (λ) ranged from 0.14
yr-1 to 5.77 yr-1, and was significantly higher (2.2 times) in male than female ferrets.
Statistical hypothesis testing revealed transmission of M. bovis to ferrets
occurred from both brushtail possums and ferrets. The force of M. bovis infection in
ferrets was reduced by 88% (λ=0.3 yr-1 vs. λ=2.5 yr-1) at sites with reductions in the
population density of sympatric brushtail possum populations. A smaller decline in the
force of infection resulting from the lethal cross-sectional sampling of the ferret
populations was also demonstrated.
The modelling approach estimated the basic reproductive rate (Ro) of M. bovis
infection in ferrets in New Zealand to vary from 0.17 at the lowest population density
(0.5 km-2) recorded to 1.6 at the highest population density (3.4 km-2) recorded. The
estimates of Ro were moderately imprecise, with a coefficient of variation of 76%.
Despite this imprecision, the Ro for M. bovis infection in ferrets was significantly less
than unity for all North Island sites surveyed. Hence it is inferred ferrets are spillover
hosts (0<Ro<1) for M. bovis infection in these environments. That is, M. bovis infection
will progressively disappear from these ferret populations if the source of inter-specific
transmission is eliminated. The estimates of Ro for M. bovis infection in South Island
ferret populations were above one (the level required for disease establishment) for a
number (5/10) of populations, though the imprecision made it impossible to ascertain
whether Ro was significantly greater than one. The estimated threshold population
density (Kt) for disease establishment was 2.9 ferrets km-2. It is inferred that, given
sufficient population density (>Kt), the rate of intra-specific transmission of M. bovis
among ferrets is sufficient for the disease to establish in ferrets in the absence of interspecific
transmission. In these areas, ferrets would be considered maintenance hosts for
the disease. Active management (e.g., density reduction or vaccination) of ferrets
would be required to eradicate M. bovis from ferret populations in these areas, in
addition to the elimination of sources of inter-specific transmission, particularly brushtail possums.
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Compósitos poliméricos reforçados por tecidos multiaxiais acoplados: anisotropia, configuração e concentração da deformaçãoFontes, Raphael Siqueira 14 December 2017 (has links)
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Previous issue date: 2017-12-14 / A proposta desta Tese de Doutorado é determinar a influência na resposta mecânica de laminados compósitos à base de tecidos multiaxiais acoplados de fibras de vidro-E e matriz epóxi éster vinílica, quando em presença de descontinuidade geométrica, aqui caracterizada por um furo circular. Nesse estudo do fenômeno da concentração de tensão é dado ênfase ao comportamento da deformação na vizinhança do furo, tendo em vista a característica do tecido de reforço ter suas camadas básicas acopladas através de fios de costura, tornando-os mais compactos em sua capacidade de suporte de carga. Esse estudo é desenvolvido a partir da medição das deformações na vizinhança do furo, utilizando a técnica de medição por Extensometria, frente aos ensaios de tração uniaxial. Por fim, serão apresentados os resultados em termos quantitativos sobre o efeito da presença da descontinuidade geométrica, mediante os cálculos da Resistência Residual (RS), do Módulo Residual (RM) e dos Fatores de Concentração de Tensão (K, calculados a partir de variados métodos analíticos), além da determinação das distribuições das deformações (obtidas das leituras dos extensômetros) na vizinhança do furo nos laminados em estudo, nas orientações 0°, 90° e 45° dos CPs. Essas distribuições são validadas utilizando a solução analítica proposta por Lekhnitskii (1968) e Konish e Whitney (1975), amplamente utilizada para materiais compósitos ortotrópicos. Ao ser efetuada a comparação entre os valores medidos experimentalmente e as distribuições analíticas das deformações, observou-se pouca interferência dos valores de K adotados para a obtenção das curvas analíticas, resultando numa concordância entre os valores obtidos pelos extensômetros e o modelo analítico. / The proposal of this Doctoral Thesis is to determine the influence on the mechanical response of composite laminates based on E-glass multiaxial Non-Crimp Fabrics and epoxy vinyl ester matrix, with the presence of geometric discontinuity, here characterized by a circular hole. In this study of the stress concentration phenomenon, emphasis is given to the strain behavior in the vicinity of the hole, since the reinforcing fabric characteristic, whose basic layers are coupled by stitching, making them more compact in their load support capacity. This study is developed from the strain measurement in the vicinity of the hole, using the technique of measurement by strain gages, during uniaxial tensile tests. Finally, the effect of the presence of the geometric discontinuity will be presented in quantitative terms, by means of the Residual Strength (RS), Residual Modulus (RM) and the Stress Concentration Factors (K, obtained by different analytical methods), in addition to the determination of strain distributions (obtained from strain gage measurements) in the vicinity of the hole in the laminates under study, in 0°, 90° and 45° orientations of the specimens. These distributions are validated using the analytical solution proposed by Lekhnitskii (1968) and Konish and Whitney (1975), widely used for orthotropic composite materials. When comparing the experimentally measured values with the analytical distributions of the strains, was observed little interference of the K values adopted to obtain the analytical curves, resulting in an agreement between the values obtained by the strain gages and the analytical model.
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[pt] CONCENTRAÇÃO DE TENSÕES PROVOCADA POR UM FURO NA PAREDE LATERAL DE UM CILINDRO OCO / [en] STRESS CONCENTRATION CAUSED BY A HOLE IN THE SIDE WALL OF A HOLLOW CYLINDERLUIZ OTÁVIO BRITO DE SOUZA FERREIRA 24 November 2011 (has links)
[pt] A determinação do fator teórico ou geométrico de concentração de tensões em um cilíndrico oco de paredes espessas com furo lateral oblíquo é o objeto deste estudo. É analisada a influência do ângulo de ineliação do furo lateral sobre o fator teórico de concentração de tensões. Foi usado na análise, o método fotoelástico. Os cilindros foram fabricados com uma mistura de araldite CY-205, anidrido ftálico e anidrido maleico. O carregamento é feito, introduzindo-se no cilindro um pino fabricado com o mesmo material. É usada a técnica do congelamento das tensões. Para determinar as tensões, o cilindro é cortado em fatias que são analisados em um polariscópio. São apresentadas conclusões, formuladas a partir dos resultados obtidos na experiência. Com este trabalho, novos dados são acrescidos ao problema de concentração de tensões, ampliando os recursos para aqueles que se dedicam ao projeto de máquinas. / [en] The study deals with the problem of concentration of stress introduced by the oblique hole in th thick wall cylinder. The influence of the angle of the axes of hole and cylinder in the stress concentration factor is studied by the method of three-dimensional photoelasticity. The cylinder was manufactured from the CIBA CY-205 epoxy resin cured by mixture of phtalic and maleic anhydrides, loaded by the inner pin and studied by the stress freezing method. The results are presented, which forms of dimensionless diagrams, which permits designer to calculate stresses using the simple Lame’s formula.
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