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Elementos finitos (via resíduos ponderados) na resolução do problema de segunda ordem das placas. / Second order theory of thin plates. Application of the weighted residual and Finite Element Methods.Costa, Henrique de Britto 29 September 1986 (has links)
Este trabalho aborda os conceitos básicos da teoria de segunda ordem das placas elásticas delgadas, utilizando o Método dos Elementos Finitos (introduzido através do Método dos Resíduos Ponderados, na variante de Galerkin). São deduzidas as matrizes de rigidez geométrica, de rigidez secante e de rigidez tangente, relativas ao problema em consideração. É proposta ainda uma conduta notavelmente simplificada, que facilita sobremaneira a construção da matriz de rigidez tangente. / This paper delas with the basic concepts of the secondf order theory of thin elastic plates, through the use of the Finite Element Method 9introcuced through the Weighted Residual Method, in Galerkin\'s approach). The matrices of geometric stiffness, secant stiffness, and tangent stiffness for the problem under consideration are deduced. It is also proposed an outstandingly simplified conduct, which will greatly easen the construction of the tangent stiffness matrix.
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Estudo randomizado comparando dois dispositivos de proteção cerebral no implante de stent carotídeo: avaliação de novos focos isquêmicos através das sequências de difusão por ressonância magnética. / A randomized study comparing two cerebral protection devices in carotid artery stenting: evaluation of new ischemic lesions through the sequence of diffusion weighted magnetic resonance imagingCano, Manuel Nicolas 03 October 2012 (has links)
Introdução: O Stent Carotídeo (SC) surgiu como uma alternativa à cirurgia de endarterectomia para o tratamento de estenose carotídea extracraniana com o objetivo de prevenir o acidente vascular encefálico (AVE). O sucesso do SC depende de estratégias que minimizem o risco de AVE. No início do estudo não existiam estudos randomizados comparando o implante de stent carotídeo com diferentes tipos de proteção cerebral. Objetivos: Testar de forma aleatória a eficácia de dois diferentes princípios de proteção embólica no território carotídeo (Angioguard®) e Mo.Ma), utilizando a ressonância magnética ponderada em Difusão (RM-PD) para detectar novas lesões isquêmicas no encéfalo analisando número, tamanho e localização. Métodos: Sessenta pacientes submetidos ao implante do stent carotídeo (SC), foram alocados aleatoriamente para utilizar filtro distal Angioguard® (30 pacientes) e balão de oclusão proximal Mo.Ma (30 pacientes) desde julho de 2008 a 2011. Todos os pacientes realizaram RM-PD pré e 48 horas pós o SC. Os resultados foram avaliados por neurologista independente e cego ao tipo de proteção cerebral utilizada. Foram acompanhados por um período de pelo menos um ano. Os dados qualitativos foram resumidos em frequências absolutas e relativas (porcentagens) e comparados utilizando o teste quiquadrado com correção de continuidade de Yates ou o teste exato de Fisher. Os dados quantitativos foram expressos em médias e desvio-padrão, e/ou medianas e intervalos interquartis e foram comparadas utilizando o teste t de Student ou não paramétrico de Mann-Whitney. Resultados: Não houve diferença estatisticamente significativa em quanto a antecedentes clínicos ou características das lesões carotídeas entre os grupos, apenas as lesões eram mais calcificadas no grupo Angioguard® (p < 0,01). Não houve diferença entre os grupos quanto a incidência de novas lesões isquêmicas (63,3% do Angioguard® vs 66,7% do Mo.Ma, p = 0,787). Quando presentes, as lesões isquêmicas por pacientes o fizeram em número significativamente menor no grupo Mo.Ma, entre 1 e 43 lesões (mediana = 6), comparado ao grupo AngioguardÒ, entre 1 e 76 lesões (mediana = 10) com p < 0,001. Três pacientes (5%) apresentaram eventos neurológicos em até 30 dias e no seguimento de um ano, 1 paciente teve um infarto agudo do miocárdio. Conclusão: Foram observadas novas lesões isquêmicas cerebrais em mais de 60% dos pacientes que utilizaram os dois dispositivos de proteção cerebral, entretanto houve significativamente menos lesões por paciente no grupo Mo.Ma, com significância estatística p = < 0,001. A maioria das lesões foi pequena < 0,5 mm, e encontradas em território ipsilateral. Não foi observado óbito ou AVE maior no seguimento de pelo menos um ano. / Background: Carotid Stent (CAS) has emerged as an alternative to surgical carotid endarterectomy for the treatment of extracranial carotid stenosis in order to prevent stroke. The success of the CAS depends on estrategies that minimize the risk of stroke. When this study began there were no randomized trial comparing different types of cerebral protection during carotid stenting. Objectives: Randomly test the effectiveness of two different embolic protection principles in carotid artery (Angioguard®) vs Mo.Ma) using diffusion-weighted magnetic resonance imaging (DWI) to detect new ischemic lesions in the brain, analyzing the number, size and location of this new ischemic lesions between groups. Methods: Sixty patients undergoing CAS, were randomly assigned to use distal filter AngioguardÒ (30p) and proximal balloon occlusion Mo.Ma (30p) from July 2008 to July 2011. All patients underwent DWI before and 48 hours after the CAS. The results were evaluated by an independent neuroradiologist blind to the type of cerebral protection used. The patients were followed during at least year. Qualitative data were summarized as absolute and relative frequencies (percentages) and compared using chisquare test with Yates continuity correction or Fisher\'s exact test. Quantitative data were expressed as means and standard deviations, and / or medians and interquartile ranges and were compared using the Student t test or nonparametric Mann-Whitney test. Results: Demographic, clinical and lesion characteristics were not different between the two groups, there were more calcified lesion in the Angioguard® group (p < 0.001). There was no difference between groups regarding the incidence of new ischemic lesions in the Angioguard® group compared to the Mo.Ma group (63.3% vs 66.7% p = 0.787). When present, the number of ischemic cerebral lesions per pacient were in fewer number in the Mo.Ma group (1 to 43 lesions; median = 6) compared to the Angioguard® group (1 to 76 lesions; median = 10) p < 0.001 and this difference was significant. Three patients (5%) had neurological events within 30 days with complete regression of symptoms, and one patient develop an infarction during the first year of follow-up. Conclusions: There were new cerebral ischemic lesions detected by DWI in more than 60% of the patients in both groups, on the other hand there were significantly fewer lesions per patient in those allocated to Mo.Ma as compared to Angioguard® with statistical significance p = 0.001. Most lesions were small < 0.5mm, and localized in ipsilateral territory. There was no death or disabling stroke in at least one year of follow-up.
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Model-based calibration of a non-invasive blood glucose monitorShulga, Yelena A 11 January 2006 (has links)
This project was dedicated to the problem of improving a non-invasive blood glucose monitor being developed by the VivaScan Corporation. The company has made some progress in the non-invasive blood glucose device development and approached WPI for a statistical assistance in the improvement of their model in order to predict the glucose level more accurately. The main goal of this project was to improve the ability of the non-invasive blood glucose monitor to predict the glucose values more precisely. The goal was achieved by finding and implementing the best regression model. The methods included ordinary least squared regression, partial least squares regression, robust regression method, weighted least squares regression, local regression, and ridge regression. VivaScan calibration data for seven patients were analyzed in this project. For each of these patients, the individual regression models were built and compared based on the two factors that evaluate the model prediction ability. It was determined that partial least squares and ridge regressions are two best methods among the others that were considered in this work. Using these two methods gave better glucose prediction. The additional problem of data reduction to minimize the data collection time was also considered in this work.
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Apathy and impulsivity in frontotemporal lobar degeneration syndromesLansdall, Claire Jade January 2017 (has links)
There has been considerable progress in the clinical, pathological and genetic fractionation of frontotemporal lobar degeneration syndromes in recent years, driving the development of novel diagnostic criteria. However, phenotypic boundaries are not always distinct and syndromes converge with disease progression, limiting the insights available from traditional diagnostic classification. Alternative transdiagnostic approaches may provide novel insights into the neurobiological underpinnings of symptom commonalities across the frontotemporal lobar degeneration spectrum. In this thesis, I illustrate the use of transdiagnostic methods to investigate apathy and impulsivity. These two multifaceted constructs are observed across all frontotemporal lobar degeneration syndromes, including frontotemporal dementia, progressive supranuclear palsy and corticobasal syndrome. They cause substantial patient morbidity and carer distress, often coexist and are undertreated. Using data from the Pick’s disease and Progressive supranuclear palsy Prevalence and INcidence (PiPPIN) Study, I examine the frequency, characteristics and components of apathy and impulsivity across the frontotemporal lobar degeneration spectrum. A principal component analysis of the neuropsychological data identified eight distinct components of apathy and impulsivity, separating patient ratings, carer ratings and behavioural tasks. Apathy and impulsivity measures were positively correlated, frequently loading onto the same components and providing evidence of their overlap. The data confirmed that apathy and impulsivity are common across the spectrum of frontotemporal lobar degeneration syndromes. Voxel based morphometry revealed distinct neural correlates for the components of apathy and impulsivity. Patient ratings correlated with white matter changes in the corticospinal tracts, which may reflect retained insight into their physical impairments. Carer ratings correlated with grey and white matter changes in frontostriatal, frontotemporal and brainstem systems, which have previously been implicated in motivation, arousal and goal directed behaviour. Response inhibition deficits on behavioural tasks correlated with focal frontal cortical atrophy in areas implicated in goal-directed behaviour and cognitive control. Diffusion tensor imaging was highly sensitive to the white matter changes underlying apathy and impulsivity in frontotemporal lobar degeneration syndromes. Diffusion tensor imaging findings were largely consistent with voxel-based morphometry, with carer ratings reflecting widespread changes while objective measures showed changes in focal, task-specific brain regions. White matter abnormalities often extended beyond observed grey matter changes, providing supportive evidence that white matter dysfunction represents a core pathophysiology in frontotemporal lobar degeneration. Apathy was a significant predictor of death within two and a half years from assessment, consistent with studies linking apathy to poor outcomes. The prognostic importance of apathy warrants more accurate measurement tools to facilitate clinical trials. Although causality remains unclear, the influence of apathy on survival suggests effective symptomatic treatments may also prove disease-modifying. These findings have several implications. First, clinical studies for apathy/impulsivity in frontotemporal lobar degeneration syndromes should target patients who present with these symptoms, irrespective of their diagnostic category. Second, data-driven approaches can inform the choice of assessment tools for clinical trials, and their link to neural drivers of apathy and impulsivity. Third, the components and their neural correlates provide a principled means to measure (and interpret) the effects of novel treatments in the context of frontotemporal lobar degeneration.
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Análise da influência das propriedades radiativas de um meio participante na interação turbulência-radiação em um escoamento interno não reativoFraga, Guilherme Crivelli January 2016 (has links)
A interação turbulência-radiação (TRI, do inglês Turbulence-Radiation Interaction) resulta do acoplamento altamente não linear entre flutuações da intensidade de radiação e flutuações da temperatura e da composição química do meio, e tem-se demonstrado experimentalmente, teoricamente e numericamente que este é um fenômeno relevante em diversas aplicações envolvendo altas temperaturas, especialmente em problemas reativos. Neste trabalho, o TRI é analisado em um escoamento interno não reativo de um gás participante que se desenvolve em um duto de seção transversal quadrada, para diferentes intensidades de turbulência do escoamento e considerando duas espécies distintas para a composição do fluido de trabalho (dióxido de carbono e vapor de água). O objetivo central é avaliar como a inclusão ou não da variação espectral das propriedades radiativas do meio no cálculo influencia a magnitude do TRI. Isso é feito através de simulações numéricas no código de dinâmica dos fluidos computacional Fire Dynamics Simulator (FDS), que resolve, através do método dos volumes finitos, as equações fundamentais que regem o problema – isto é, os balanços de massa, de quantidade de movimento e de energia e a equação de estado – em uma formulação adequada para baixos números de Mach, utilizando um algoritmo de solução explícito e de segunda ordem no tempo e no espaço. A turbulência é modelada através da simulação de grandes escalas (LES, do inglês Large Eddy Simulation), empregando-se o modelo de Smagorinsky dinâmico para o fechamento dos termos submalha; para a radiação térmica, o método dos volumes finitos é utilizado na discretização da equação da transferência radiativa e os modelos do gás cinza e da soma-ponderada-de-gases-cinza (WSGG, do inglês Weighted-Sum-of-Gray-Gases) são implementados como forma de desconsiderar e de incluir a dependência espectral das propriedades radiativas, respectivamente. A magnitude do TRI sobre o problema é avaliada através de diferenças entre as médias temporais dos fluxos de calor superficiais e do termo fonte radiativo obtidas em cálculos que consideram os efeitos do fenômeno e cálculos que os negligenciam. Em geral, a interação turbulência-radiação mostrou ser pouco importante em todos os casos considerados, o que concorda com resultados de outros estudos sobre o tema em escoamento não reativos. Com o modelo WSGG, as contribuições do fenômeno foram maiores do que com a hipótese do gás cinza, evidenciando que a inclusão da variação espectral na solução do problema radiativo tem um impacto sobre a magnitude dos efeitos do TRI. Além disso, é feita uma discussão, em parte inédita no contexto do TRI, sobre diferentes metodologias para a análise do fenômeno. Finalmente, é proposto um fator de correção para o termo fonte radiativo médio no modelo WSGG, que é validado através de sua implementação nos casos simulados. Em estudos futuros, uma análise de sensibilidade sobre os termos constituintes desse fator de correção pode levar a um melhor entendimento de como as flutuações de temperatura se correlacionam com o fenômeno da interação turbulência-radiação. / Turbulence-radiation interaction (TRI) results from the highly non-linear coupling between fluctuations of radiation intensity and fluctuations of temperature and chemical composition of the medium, and its relevance in a number of high-temperature problems, especially when chemical reactions are included, has been demonstrated experimentally, theoretically, and numerically. In the present study, the TRI is analyzed in a channel flow of a non-reactive participating gas for different turbulence intensities of the flow at the inlet and considering two distinct species for the medium composition (carbon dioxide and water vapor). The central objective is to evaluate how the inclusion or not of the spectral variation of the radiative properties of a participating gas in the radiative transfer calculations affects the turbulence-radiation interaction. With this purpose, numerical simulations are performed using the computational fluid dynamics Fortranbased code Fire Dynamics Simulator, that employs the finite volume method to solve a form of the fundamental equations – i.e., the mass, momentum and energy balances and the state equation – appropriate for low Mach number flows, through an explicit second-order (both in time and in space) core algorithm. Turbulence is modeled by the large eddy simulation approach (LES), using the dynamic Smagorinsky model to close the subgrid-scale terms; for the thermal radiation part of the problem, the finite volume method is used for the discretization of the radiative transfer equation and the gray gas and weighted-sum-of-gray-gases (WSGG) models are implemented as a way to omit and consider the spectral dependence of the radiative properties, respectively. The TRI magnitude in the problem is evaluated by differences between values for the time-averaged heat fluxes at the wall (convective and radiative) and for the time-averaged radiative heat source calculated accounting for and neglecting the turbulence-radiation interaction effects. In general, TRI had little importance over all the considered cases, a conclusion that agrees with results of previous studies. When using the WSGG model, the contributions of the phenomenon were greater that with the gray gas hypothesis, demonstrating that the inclusion of the spectral variance in the solution of the radiative problem has an impact in the TRI effects. Furthermore, this paper presents a discussion, partly unprecedented in the context of the turbulence-radiation interaction, about the different methodologies that can be used for the TRI analysis. Finally, a correction factor is proposed for the time-averaged radiative heat source in the WSGG model, which is then validated by its implementation in the simulated cases. In future studies, a sensibility analysis on the terms that compose this factor can lead to a better understanding of how fluctuations of temperature correlate with the turbulence-radiation interaction phenomenon.
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Aplicação do modelo da soma-ponderada-de-gases-cinza na simulação da transferência radiativa em chamas difusivas laminares de metano diluído com CO2 e N2Rodrigues, Luís Gustavo Pires January 2016 (has links)
Simulações acopladas do escoamento reativo e dos processos de transferência de calor para o estudo de chamas são problemas dispendiosos computacionalmente. A transferência de calor por radiação em processos de combustão, devido às elevadas temperaturas, é o processo de troca energética dominante. Ainda, o comportamento altamente irregular do coeficiente de absorção com o comprimento de onda se constitui em uma dificuldade adicional na modelagem da transferência radiativa em meios participantes. Para contornar essa dificuldade modelos espectrais foram desenvolvidos com o objetivo de simular o comportamento de um gás real. Dentre esses modelos destacam-se o gás cinza (GG: Gray Gas), o mais simples, que negligencia o comportamento espectral do coeficiente de absorção, e o modelo da soma-ponderada-de-gases-cinza (WSGG: Weighted-Sum-of-Gray-Gases) onde a integração sobre todo o espectro é substituída por um número finito de gases cinza. Com o avanço de ferramentas computacionais, principalmente códigos CFD (Computational Fluid Dynamics), abordagens computacionais se tornaram atrativas frente ou em complemento às abordagens experimentais. Desse modo, o presente trabalho tem por objetivo a aplicação dos modelos WSGG e GG com novas correlações na simulação detalhada de chamas difusivas laminares de metano diluído com dióxido de carbono e nitrogênio com o código CFD comercial ANSYS/Fluent. Foram desenvolvidas rotinas de usuário (UDF: User-Defined Functions) para o acoplamento dos modelos espectrais ao código CFD. A verificação das rotinas de usuário foi realizada comparando os resultados obtidos via simulação Fluent com dados obtidos pelo modelo WSGG com um código FORTRAN próprio desenvolvido pelo grupo de pesquisa do Laboratório de Radiação Térmica (LRT/UFRGS) para o problema unidimensional de superfícies negras e infinitas preenchidas por um meio não-isotérmico e não-homogêneo. Os erros encontrados para o fluxo de calor radiativo nas superfícies e para o termo fonte radiativo ao longo do meio foram da ordem de 1% indicando o funcionamento correto das rotinas UDF acopladas ao Fluent. Por fim, as rotinas foram aplicadas na simulação numérica para chamas de potência constante com diluição dos reagentes e os dados obtidos com a solução numérica foram comparados com dados experimentais para a fração radiante e fluxo de calor radiativo. Os desvios médios encontrados para o fluxo de calor radiativo ficaram em torno de 10% para todas as chamas, excetuando as chamas com diluição de CO2 de 30%, 40% e 50%, em volume, para as quais os desvios médios ficaram em torno de 15%. O termo fonte para as chamas apontou para a predominância da emissão do meio em relação à absorção. Todas as chamas estudadas se encontram no regime opticamente fino (optically thin) para o qual, segundo apontam estudos da literatura, a escolha do modelo espectral possui impacto pequeno em resultados globais da chama como a temperatura e a concentração das espécies na mistura. Nesse aspecto os resultados encontrados concordaram com a previsão da literatura, entretanto para a transferência radiativa, o modelo GG se mostrou sensivelmente menos preciso em comparação ao modelo WSGG, principalmente para a fração radiante e para o fluxo radiativo na região da pluma aquecida, indicando a dependência do modelo espectral adotado. / Coupled simulations of the reactive flow with the heat transfer processes for flame studying are computationally demanding problems. The radiative transfer in combustion processes is the main heat transfer mechanism due to the high temperatures involved. However, the highly irregular behavior o f the absorption coefficient with the wavenumber composes in an additional difficulty on modeling the radiative transfer in participating media. In order to overcome this issue, spectral models were developed with the objective of simulate the behavior of real gases. Some of the most known models are the gray gas (GG) for which the spectral behavior of the radiative properties of the medium is neglected and the weighted-sum-of-gray-gases (WSGG) for which the integration over the entire spectrum is replaced by a summation over a finite number of gray gases with constant absorption coefficients. With the development of computational tools, mainly Computational Fluid Dynamics (CFD) codes, numerical approaches became attractive instead or in complement of experimental set ups. In this way, the present work aims to couple the WSGG and the GG models with new correlations in a detailed simulation of diffusive laminar flames of methane diluted with carbon dioxide and nitrogen with the commercial CFD code ANSYS/Fluent. User-defined functions (UDF) were developed to the coupling of the spectral models. The verification was carried out through the WSGG model by comparing the Fluent solution with a solution obtained with a FORTRAN code developed by the Thermal Radiation Laboratory (LRT/UFRGS) research group for the one-dimensional system of black surfaces filled with a non-homogeneous and non-isothermal medium. The deviations for the radiative heat flux for the walls and the radiative heat source along the domain were of 1% or less, indicating the correct coupling between the UDF routines and the CFD code. Finally, the UDF were applied in the solution of constant power flames with fuel diluted with carbon dioxide and nitrogen. The obtained data was then compared with experimental measurements for the radiant fraction and the radiative heat flux along the flame axis. The average deviations found were in order of 10% for all flames, except for the flames with 30%, 40% and 50% of CO2 dilution, in volume, for which the deviatioms found were in order of 15%. The radiative heat source was plotted and indicated for the medium emission predominance in comparison with the medium absorption. All flames studied were optically thin flames for which, studies pointed, the spectral model have minor impact over global results as flame temperature and mixture concentration. For this aspect the results found showed agreement with the literature studies predictions, however the GG model showed itself less accurate in comparison with the WSGG model for the radiant fraction and the radiative heat flux computations. So the spectral models have influence on the radiative transfer even if its effect on flame structure can be negligible.
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Patrons d'organisation des traits aériens et racinaires en prairies humides : liens avec la production primaire (quantité et qualité). / Root and shoot trait patterns in wet grasslands : effects on fodder provision.Chanteloup, Pierre 16 January 2013 (has links)
Les prairies semi-naturelles constituent des espaces multifonctionnels susceptibles de rendre de nombreux services à la société. Ce sont en particulier des agro-écosystèmes favorables à l’expression d’une grande diversité floristique et faunistique permettant de concilier enjeux écologiques et agronomiques. Ce travail de thèse vise à analyser (i) l'influence des facteurs environnementaux sur l'assemblage des communautés in situ et (ii) les relations entre la structure fonctionnelle des assemblages (i.e. valeurs de traits agrégées et diversité fonctionnelle) et leurs performances (i.e. production de biomasse et digestibilité de cette biomasse). Cette étude s'appuie sur des approches expérimentales et de terrain dans les prairies humides pâturées du Marais Poitevin. Nos résultats montrent des réponses très différentes des traits aériens et racinaires étudiés aux gradients de stress et de perturbation rencontrés dans ces prairies. Ils ont également permis de mettre en évidence l'influence prépondérante des valeurs de traits agrégées sur la fourniture de services écosystémiques (i.e. productivité et digestibilité du fourrage), en accord avec la "Biomass ratio hypothesis" énoncée par Grime. L'influence du niveau de diversité fonctionnelle sur les services rendus par les assemblages varie selon le service considéré. Contrairement aux résultats attendus selon la "Diversity hypothesis" énoncée par Tilman, le niveau de diversité fonctionnelle est lié négativement à la productivité des assemblages. En revanche, un effet positif de la diversité fonctionnelle sur la digestibilité a été mis en évidence. Cette étude a par ailleurs permis de montrer un compromis entre la productivité des assemblages et la digestibilité de la biomasse produite dans ces prairies humides. Ce travail suggère que des outils de diagnostics de la valeur fourragère du couvert peuvent être construits sur la base de la structure fonctionnelle des assemblages, et ce avec un haut niveau de fiabilité. Il met également en avant les bénéfices agronomiques associés à l'hétérogénéité des couverts végétaux rencontrés dans ces prairies. / Semi-natural grasslands form multifunctional areas susceptible to serve the society from many aspects. Indeed, they are agro-ecosystems that promote expression of a large floristic and faunistic diversity, which allows conciliating ecologic and agronomic issues. This PhD work aims at analysing (i) influence of environmental factors on natural communities' assembly rules and (ii) the relationships between the functional structure of assemblages (i.e. community weighted mean trait values and functional diversity) and their performances (i.e. biomass production and its digestibility). This study is based on both experimental and field approaches in the Marais Poitevin wet grasslands. Our results show that the studied aerial and root traits display a wide diversity of answers to stress gradients and disturbances encountered in these grasslands. Our results also highlighted the crucial influence of community weighted mean trait values on provision of ecosystem services (i.e. forage productivity and digestibility), in agreement with the Biomass ratio hypothesis set out by Grime. The influence of the functional diversity level on services provided by the assemblages differs depending on the service considered. Contrary to the results expected according to the Diversity hypothesis of Tilman, the functional diversity level is negatively correlated with the productivity of the assemblages. However, our study points to a positive feedback between functional diversity and digestibility. Furthermore, this study demonstrated the existence of trade-off between the productivity of assemblages and the digestibility of biomass produced in these wet grasslands. This work suggests that highly reliable tools can be established, based on the functional structure of assemblages, to evaluate the feeding value of a vegetal cover. This work finally illustrates the agronomic benefits associated with heterogeneous vegetal covers encountered in these grasslands.
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Sobre reticulados de Coxeter-Toda / On Coxeter-Toda latticesEber Daniel Chuño Vizarreta 29 March 2016 (has links)
Esse trabalho visa a investigar a estrutura bi-Hamiltoniana de uma classe de sistemas dinâmicos. Depois de introduzir as ferramentas necessárias, a saber, as noções de variedade de Poisson, de grupo de PoissonLieedenetworknodiscoenoanêl,introduziremosossistemasdinâmicos relevantes nessa dissertação, chamados de reticulados de Coxeter-Toda. Esses sistemas dinâmicos, cujo espaço de fase pode ser identicado com umoportunoquocientedeumacéluladupladeCoxeter-Bruhatdogrupo linear geral, são obtidos por redução do sistema de Toda em GLn. Na parte nal do presente trabalho apresentaremos alguns resultados relacionado à um sistema dinâmico discreto chamado de aplicação do pentagrama, o qual pode ser obtido através uma oportuna discretização do sistema dinâmico de Boussinesq. / This work aims to study the bi-Hamiltonian structure of a class of dynamical systems. After introducing the relevant tools, namely the notions of Poisson manifold, Poisson-Lie group and of network dened in a disc and in an annulus, we will introduce the dynamical systems of interest for this dissertation, i.e., the Coxeter-Toda lattices. These dynamical systems, whose phase-space can be identied with a suitable quotient of a Coxeter double Bruhat cell of the general linear group, are obtained by reduction starting from the Toda ow on GLn. In the nal part of the present work will be presented some results concerning a discrete integrable system close to the so called Pentagram map, which is a discretization of the Boussinesq dynamical system..
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Estudo para adaptação de um método de classificação de estradas não pavimentadas às condições do Município de São Carlos/SP / not availableHeliana Barbosa Fontenele 26 November 2001 (has links)
Este trabalho trata do estudo para adaptação de um método de classificação de estradas não pavimentadas às condições encontradas em campo no município de São Carlos-SP. O trabalho foi desenvolvido a partir de avaliações subjetivas e objetivas levadas a efeito por um painel de avaliadores que executou levantamento de campo planejado, com base nas informações contidas nos relatórios técnicos sobre o desenvolvimento de dois métodos de classificação das condições de estradas - método do Pavement Condition Index e método do Unsurfaced Road Condition Index. O painel de avaliadores atribuiu notas a 140 unidades amostrais de 30 metros de comprimento, a cada defeito presente na unidade amostral e aos 14 trechos estudados. Paralelamente, cada unidade amostral e cada trecho receberam uma classificação de acordo com o método do Unsufaced Road Condition Index. Concluiu-se que, para o presente estudo, não há correlação entre os resultados da avaliação subjetiva executada apenas com o emprego de uma escala de notas e da objetiva, calculada segundo o método do Unsurfaced Road Condition Index. Conclui-se também que a avaliação subjetiva global do trecho tem uma boa correlação com a avaliação subjetiva do conjunto das unidades amostrais que compõem o referido trecho, indicando ser coerente a avaliação do painel de avaliadores. / This work deals with a study for adapting an unpaved road rating method to the field condition prevailing in São Carlos County. The research was carried out through subjective and objective evaluations performed by a panel of raters during field inspections. The experiment was planned accordingly to the technical reports information about the development of two roads condition rating methods - the Pavement Condition lndex and the Unsurfaced Road Condition lndex. The panel rated 140 sample unities of 30 m long attributing a value for the unity, for each defect they have and for 14 road sections studied. The ranks were also calculated accordingly to Unsurfaced Road Condition lndex method. It was concluded that, for the present research, there is no correlation between the subjective evaluation executed with a simple scale and the objective rating calculated following the Unsurfaced Road Condition lndex method. It was also concluded that the global subjective rank of the road section has a good correlation with the subjective rank of the set of sample unities that composes this section, indicating the coherence of the rating panel evaluation.
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Stanovení hodnoty podniku působícího ve stavebnictví / Estimation of the Value of the Firm from the Construction BranchBaranovičová, Zuzana January 2015 (has links)
The diploma thesis deals with the determination of the value of the company from the construction branch. The thesis is divided into two parts. The first part aims at the methods of the determination of the value of the company. The theoretical knowledge is applied in the second part, namely in subsections about strategic, financial analysis and the evaluation by the yield method of discounted cash flow. Programs Stratex and Evalent are used to determine the value. The conclusion of the thesis includes the determination of the value of the company applied to 1st January 2014.
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