Controls on denudation in the eastern Bolivian Andes are evaluated by synthesis of new and existing denudation estimates from basin-morphometry, stream - powered fluvial incision, landslide mapping, sediment flux, erosion surfaces, thermochronology, foreland basin sediment volumes, and structural restorations. Centered at 17.5 °S, the northeastern Bolivian Andes exhibit high relief, a wet climate, and a narrow fold- thrust belt. In contrast, the southeastern Bolivian Andes have low relief, a semi-arid climate, and a wide fold-thrust belt. Basin -morphometry indicates a northward increase in relief and relative denudation. Stream-power along river profiles shows greater average incision rates in the north by a factor of 2 to 4. In the south, profile knickpoints with high incision rates are controlled by fold-thrust belt structures such as the surface expressions of basement megathrusts, faults, folds, and lithologic boundaries. Landslide and sediment-flux data are controlled by climate, elevation, basin morphology, and size and show a similar trend; short -term denudation-rate averages are greater in the north (1- 9 mm/yr) than the south (0.3-0.4 mm/yr). Long-term denudation-rate estimates including fission track, basin fill, erosion surfaces, and structural restorations also exhibit greater values in the north (0.2-0.8 mm/yr) compared to the south (0.04-0.3 mm/yr). Controls on long-term denudation rates include relief, orographic and global atmospheric circulation patterns of precipitation, climate change, glaciation, and fold-thrust belt geometry and kinematics. The denudation synthesis supports two conclusions: 1) denudation rates have increased towards the present 2) an along-strike disparity in denudation (greater in the north) has existed since at least the Miocene and has increased towards the present. Denudation rates and controls suggest that Bolivian mountain morphology is controlled by both its orientation at mid-latitude, and the feedbacks between uplift, kinematics, orographic effects on precipitation, glaciation, and the increased erosion that accompanies orogenesis.

Anthropogenic climate change is approaching predicted tipping points and there is an urgent need to de-carbonize energy systems on a global scale. Generation technologies that do not emit greenhouse gas need to be rapidly deployed, and energy grids need to be updated to accommodate an intermittent fluctuating supply. Rapidly advancing battery technology, cost reduction of solar and wind power and other emerging generation technologies are making the needed changes technically and economically feasible. Extracting energy from fast-flowing tidal currents using turbines akin to those used in wind farms, offers a reliable and predictable source of GHG free energy. The tidal power industry has established the technical feasibility of tidal turbines, and is presently up-scaling deployments from single isolated units to large tidal farms containing many turbines. However there remains significant economic uncertainty in financing such projects, partially due to uncertainty in predicting the long-term energy yield. Since energy yield is used in calculating the project revenue, it is of critical importance. Predicting yield for a prospective farm has not received sufficient attention in the tidal power literature. this task has been the primary motivation for this thesis work, which focuses on establishing and validating simulation-based procedures to predict flows through large tidal farms with many turbines, including the back effects of the turbines. This is a challenging problem because large tidal farms may alter tidal flows on large scales, and the slow-moving wake downstream of each rotor influences the inflow to other rotors, influencing their performance and loading. Additionally, tidal flow variation on diurnal and monthly timescales requires long-duration analysis to obtain meaningful statistics that can be used for forecasting. This thesis presents a hybrid simulation method that uses 2D coastal flow simulations to predict tidal flows over long durations, including the influence of turbines, combined with higher-resolution 3D simulations to predict how wakes and local bathymetry influence the power of each turbine in a tidal farm. The two simulation types are coupled using a method of bins to reduce the computational cost within reasonable limits. The method can be used to compute detailed 3D flow fields, power and loading on each turbine in the farm, energy yield and the impact of the farm on tidal amplitude and phase. The method is demonstrated to be computationally tractable with modest high-performance computing resources and therefore are of immediate value for informing turbine placement, comparing turbine farm-layout cases and forecasting yield, and may be implemented in future automated layout optimization algorithms. / Graduate

Made available in DSpace on 2016-08-19T18:20:35Z (GMT). No. of bitstreams: 1 LAURINDA FERNANDA SALDANHA SIQUEIRA.pdf: 940563 bytes, checksum: 997451038c9761fcacf436b4488d38e5 (MD5) Previous issue date: 2010-03-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / What has been observed on the beaches of the island of Maranhao (Brazil) is an intense process of urbanization started from the 70's, not always accompanied by urban space structuring and planning, causing many environmental problems, mainly with respect to environmental sanitation. In coastal areas, the challenge of integrated management is mainly to harmonize urban development with conservation and sustainable use. Whereas improve the quality of decisions in the management of sustainability, are necessary closer links between the results of sustainability monitoring and the policy responses of decision makers. Under the hypothesis that increasing levels of total coliform in the beaches water, as indicative of contamination by domestic sewage and therefore a poor urban planning, are results of the performance variables of urban sprawl and sanitation indicators, had the objective to propose tools to aid the integrated management and sustainability in the form of time series and numerical predictive models of levels of total coliform bacteria in water from the beaches of Ponta da Areia, São Marcos, Calhau, Olho d Água and Araçagy, coastline of the island of Maranhao (Brazil). To this end, a study was performed documental and field research to obtain data about urban sprawl, sanitation and water quality of the beaches studied for construction and analysis of time series of total coliform in water, study the correlations between variables urban expansion and sanitation on the levels of total coliforms and construction and proposal of numerical models based in correlations found and peculiarities of the beaches studied. The results indicate confirmation of research hypothesis. The analysis of time series indicated a significant increase in levels of total coliform in the water of the beaches studied, being more significant on the beaches Calhau, São Marcos and Olho d Água, and less significant on the beaches of Ponta da Areia and Araçagy. The amplitude of the seasonal behavior of these levels was variable, subject to seasonal multiplicative factors responsible for checking the variability, this strike was obtained which allowed equations to calculate them for each time period. The variables explained most of the growth of total coliforms in water and are used in the construction of predictive numerical models, was urban population, population density, number of households connected to the sewer system, number of households with inadequate sewage, water pH and release numbers in natura sewage on the beaches, associated characteristics of each beach in the form of seasonal factors obtained by the time series analysis. This study is an indirect measurement and should be used as an alternative tool in the sustainable management of the area studied and evaluation of public policies to the management of water resources. The research merit on integrated coastal management was to represent reverse direction to the your proposed goals and sustainability of the coastline of the island of Maranhão (Brazil). / O que se tem observado nas praias da Ilha do Maranhão (Brasil) é um processo intenso de urbanização iniciado a partir da década de 70, nem sempre acompanhado por uma estruturação e planejamento do espaço urbano, ocasionando inúmeros problemas ambientais, principalmente no que concerne ao saneamento ambiental. Nas áreas costeiras o desafio do gerenciamento integrado está, sobretudo, em harmonizar o desenvolvimento urbano com a conservação e o uso sustentável. Neste âmbito, considerando a melhoria da qualidade das decisões em gestão da sustentabilidade, são necessárias relações mais estreitas entre os resultados do monitoramento da sustentabilidade e as respostas políticas dos tomadores de decisão. Sob a hipótese de que os níveis crescentes de coliformes totais na água das praias, como indicativos de contaminação por esgotos domésticos e, por conseguinte de um planejamento urbano deficiente, são resultado da atuação de variáveis de expansão urbana e de indicadores de saneamento básico, teve-se o objetivo propor ferramentas de auxilio ao gerenciamento costeiro integrado na forma de séries temporais e modelos numéricos preditivos dos níveis de coliformes totais na água das praias da Ponta da Areia, São Marcos, Calhau, Olho d água e Araçagy, da orla marítima da Ilha do Maranhão (Brasil). Neste intuito, foi realizada pesquisa documental e em campo para obtenção de dados referentes à expansão urbana, ao saneamento básico e à qualidade da água das praias estudadas, para construção e análise das séries temporais de coliformes totais na água, estudo das correlações entre as variáveis de expansão urbana e saneamento básico sobre os níveis de coliformes totais e para construção e proposição de modelos numéricos com base nas correlações identificadas e nas peculiaridades das praias estudadas. Os resultados indicam confirmação da hipótese da pesquisa. A análise das séries temporais indicou haver tendência crescente nos níveis de coliformes totais na água das praias em estudo, sendo mais significativa nas praias do Calhau, São Marcos e Olho d Água, e menos significativa nas praias da Ponta da Areia e Araçagy. A amplitude da sazonalidade do comportamento destes níveis foi variável, condicionada a fatores sazonais multiplicativos responsáveis por conferir a variabilidade, neste intento obteve-se equações que permitiram calculá-los para cada período de tempo. As variáveis que mais explicaram o crescimento dos níveis de coliformes totais na água, sendo utilizadas na construção dos modelos numéricos preditivos, foram população urbana, densidade populacional, número de domicílios ligados a rede coletora de esgotos, número de domicílios com estruturas inadequadas de esgotamento sanitário, pH da água e números de lançamento de esgoto in natura nas praias, associadas as peculiaridades de cada praia na forma de fatores sazonais obtidos pela análise das séries temporais. Há de se ter em mente que este estudo é uma aferição indireta e que deve ser utilizada como instrumento subsidiário na gestão sustentável do espaço estudado e na avaliação das políticas públicas traçadas na área de gerenciamento dos recursos hídricos. O mérito da pesquisa diante o gerenciamento costeiro integrado foi verificar o retrocesso em direção às suas metas e à sustentabilidade da orla marítima da Ilha do Maranhão (Brasil).

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L’analyse dynamique des structures de grandes dimensions incluant de nombreux paramètres incertains et des non-linéarités localisées ou réparties peut être numériquement prohibitive. Afin de surmonter ce problème, des modèles d’approximation peuvent être développés pour reproduire avec précision et à faible coût de calcul la réponse de la structure.L’objectif de la première partie de ce mémoire est de développer des modèles numériques robustes vis-à-vis des modifications structurales (non-linéarités localisées, perturbations ou incertitudes paramétriques) et « légers » au sens de la réduction de la taille. Ces modèles sont construits, selon les approches de condensation directe et par synthèse modale, en enrichissant des bases de réduction tronquées, modale et de Craig-Bampton respectivement, avec des résidus statiques prenant compte des modifications structurales. Pour propager les incertitudes, l’accent est mis particulièrement sur la méthode du chaos polynomial généralisé. Sa combinaison avec les modèles réduits ainsi obtenus permet de créer des métamodèles mono et bi-niveaux, respectivement. Les deux métamodèles proposés sont comparés à d’autres métamodèles basés sur les méthodes du chaos polynomial généralisé et du Latin Hypercube appliquées sur des modèles complets et réduits. Les métamodèles proposés permettent d’approximer les comportements structuraux avec un coût de calcul raisonnable et sans perte significative de précision.La deuxième partie de ce mémoire est consacrée à l’analyse dynamique des structures périodiques non-linéaires en présence des imperfections : perturbations des paramètres structuraux ou incertitudes paramétriques. Deux études : déterministe ou stochastique, respectivement, sont donc menées. Pour ces deux configurations, un modèle analytique discret générique est proposé. Il consiste à appliquer la méthode des échelles multiples et la méthode de perturbation pour résoudre l’équation de mouvement et de projecter la solution obtenue sur des modes d’ondes stationnaires. Le modèle proposé conduit à un ensemble d’équations algébriques complexes couplées, fonctions du nombre et des positions des imperfections dans la structure. La propagation des incertitudes à travers le modèle ainsi construit est finalement assurée par les méthodes du Latin Hypercube et du chaos polynomial généralisé. La robustesse de la dynamique collective vis-à-vis des imperfections est étudiée à travers l’analyse statistique de la dispersion des réponses fréquentielles et des bassins d’attraction dans le domaine de multistabilité. L’étude numérique montre que la présence des imperfections dans une structure périodique renforce sa non-linéarité, élargit son domaine de multistabilité et génère une multiplicité de branches multimodale. / Dynamic analysis of large scale structures including several uncertain parameters and localized or distributed nonlinearities may be computationally unaffordable. In order to overcome this issue, approximation models can be developed to reproduce accurately the structural response at a low computational cost.The purpose of the first part of this thesis is to develop numerical models which must be robust against structural modifications (localized nonlinearities, parametric uncertainties or perturbations) and reduce the size of the initial problem. These models are created, according to the direct condensation and the component mode synthesis, by enriching truncated reduction modal bases and Craig-Bampton transformations, respectively, with static residual vectors accounting for the structural modifications. To propagate uncertainties through these first-level and second-level reduced order models, respectively, we focus particularly on the generalized polynomial chaos method. This methods combination allows creating first-level and second-level metamodels, respectively. The two proposed metamodels are compared to other metamodels based on the polynomial chaos method and Latin Hypercube method applied on reduced and full models. The proposed metamodels allow approximating the structural behavior at a low computational cost without a significant loss of accuracy.The second part of this thesis is devoted to the dynamic analysis of nonlinear periodic structures in presence of imperfections: parametric perturbations or uncertainties. Deterministic or stochastic analyses, respectively, are therefore carried out. For both configurations, a generic discrete analytical model is proposed. It consists in applying the multiple scales method and the perturbation theory to solve the equation of motion and then on projecting the resulting solution on standing wave modes. The proposed model leads to a set of coupled complex algebraic equations, depending on the number and positions of imperfections in the structure. Uncertainty propagation through the proposed model is finally done using the Latin Hypercube method and the generalized polynomial chaos expansion. The robustness the collective dynamics against imperfections is studied through statistical analysis of the frequency responses and the basins of attraction dispersions in the multistability domain. Numerical results show that the presence of imperfections in a periodic structure strengthens its nonlinearity, expands its multistability domain and generates a multiplicity of multimodal branches.