Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-24T12:46:26Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Modelagem de sistemas hidrotérmicos interligados utilizando dinâmica de sistemas.pdf: 1401994 bytes, checksum: 2d15d929f0a041f795111bbdb652abcb (MD5) / Approved for entry into archive by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-01-24T12:47:27Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Modelagem de sistemas hidrotérmicos interligados utilizando dinâmica de sistemas.pdf: 1401994 bytes, checksum: 2d15d929f0a041f795111bbdb652abcb (MD5) / Made available in DSpace on 2017-01-24T12:47:27Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Modelagem de sistemas hidrotérmicos interligados utilizando dinâmica de sistemas.pdf: 1401994 bytes, checksum: 2d15d929f0a041f795111bbdb652abcb (MD5) Previous issue date: 2015-08-28 / A matriz de energia elétrica brasileira é composta predominantemente por geração hídrica, este fato faz com que o país dependa do regime de afluências. A fonte de geração complementar para suprir a demanda do país em períodos de baixa afluência é a geração de energia a partir de usinas termelétricas, porém cada vez que estas usinas entram em operação o custo marginal de curto prazo da energia sobe. O país possui um grande sistema elétrico interligado, em que é possível realizar o intercâmbio de energia entre as regiões, porém a decisão sobre o despacho e o intercâmbio de energia é tarefa complexa. Esta decisão é tomada pelo Operador Nacional do Sistema Elétrico (ONS) com auxílio dos modelos Newave e Decomp, porém estes modelos são complexos e pouco flexíveis, além da lenta resposta a uma determinada ação. Devido a este fato, o presente trabalho busca uma alternativa para auxiliar no teste de ações e na obtenção de respostas futuras a partir de ações adotadas no presente, com um tempo rápido de resposta. Para isto é utilizada a técnica de Dinâmica de Sistemas que busca modelar as relações de causa-efeito realimentadas, visando compreender as implicações sobre o desempenho do sistema sob estudo. O modelo elaborado leva em consideração as principais variáveis que compõem o sistema elétrico brasileiro como Energia Natural Afluente (ENA), Geração Termo, Geração Hidro, Geração eólica, Carga de Energia, Energia armazenada e o Custo Variável Unitário (CVU) das unidades térmicas. Os principais objetivos são compreender o funcionamento do Sistema Interligado Nacional, auxiliar na decisão de utilizar a água dos reservatórios no presente ou economizar para o futuro, bem como obter as consequências dessa decisão no Preço de Liquidação das Diferenças(PLD) e no intercâmbio de energia entre os subsistemas, além de analisar a influência de diferentes cenários de ENA e Geração eólica no sistema.Com o modelo desenvolvido foi possível mostrar a importância do intercâmbio de energia entre os subsistemas a fim de evitar possíveis situações de déficit. A principal contribuição do modelo foi obtida com a aplicação de cenários de ENA e Geração Eólica, com um acréscimo de 10% na curva de ENA verifica-se a redução de diversas situações com déficit e do PLD, enquanto que com uma redução de 10% na curva de ENA os períodos com déficit e o PLD alto aumentaram significativamente. / The Brazilian energy matrix is composed predominantly hydroelectric generation, this fact makes the country dependent on the inflow regime. The source of additional generation to meet the country's demand in low peak times is the generation of energy from thermal power plants, but increasingly these plants become operational marginal cost of short-term energy rises. The country has a large interconnected power system, it is possible to carry out the exchange of energy between regions, but the decision about dispatch and exchange of energy is a complex task. This decision is made by the National Electric System Operator (ONS) with the help of Newave and Decomp models, but these models are complex and inflexible, besides the slow response to a particular action. Due to this fact, this paper seeks an alternative to aid in the stock test and obtaining future responses from actions taken in the present, with a fast response time. For this is used the system dynamics technique that seeks to model the relationships of cause and effect fed back, to understand its effects on the performance of the system under study. The elaborate model takes into account the main variables that make up the Brazilian electrical system as Energy Affluent Natural (ENA), Generation Instrument, hydro generation, wind generation, power load, stored energy and the Variable Cost per Unit (CVU) of thermal units. The main objectives are to understand the operation of the National Interconnected System, assist in the decision to use water from reservoirs in the present or save for the future and get the consequences of this decision in the Settlement of Differences Price (PLD) and energy exchange between subsystems, and analyze the influence of different scenarios of ENA and wind generation in the system. With the developed model was possible to show the importance of the exchange of energy between the subsystems in order to avoid possible deficit situations. The main standard contribution was obtained by applying ENA scenarios and Generation Wind, with a 10% increase in ENA curve was possible to eliminate various situations with deficit and reduce the PLD, whereas with a 10% reduction in the curve ENA periods with high deficit and the PLD increased significantly.

Considerable effort worldwide has gone into monitoring heat and mass transfer at active volcanoes, as this information may provide clues about changes in volcanic activity and impending eruptions. One method used is the self-potential (SP) method, which has been employed on volcanoes to map hydrothermal systems and structural features and to monitor changes in the hydrothermal system due to volcanic activity. Continuous monitoring of SP has been employed on a few volcanoes and has produced encouraging results. This study presents new time series data collected from continuous monitoring stations at Masaya and Telica, and spatial series data from Masaya, Telica, and Cerro Negro, three active volcanoes in Nicaragua. The primary goals of this study were to determine whether correlations between SP anomalies and CO2 flux exist and to investigate temporal variations in temperature, SP, rainfall, and barometric pressure. To achieve these goals, SP and CO2 flux surveys were conducted on Masaya, Telica, and Cerro Negro, and continuous monitoring stations were installed on Masaya and Telica. The continuous monitoring station on Masaya recorded temperature, SP, rainfall, and barometric pressure. The station on Telica recorded temperature and SP. Profiles collected on Masaya and Cerro Negro show broad correlation between SP and CO2 flux. However, profiles on Telica revealed virtually no SP anomaly or CO2 flux for the majority of the profile, at the time of data collection. Data collected from the continuous monitoring station at Masaya showed a persistent positive SP anomaly that fluctuated between 60 and 240 mV. Rainfall was seen to supress the anomaly for time scales of several hours to several days. Correlations between temperature, SP, and barometric pressure were also seen at Masaya. Curiously, no increases in SP were seen during two temperature transients that occurred during volcanic activity in June and October. Continuous monitoring data from Telica showed only decreases in temperature and SP, which coincided with rainfall. The continuous monitoring data collected in this study and others have begun to provide a better understanding of the nature of SP anomalies, which may aid in the development of the SP method as a volcano monitoring tool.

This dissertation contributes to our understanding of the use of the Li-isotopic composition of seawater as a tracer of the earth system with a focus on the role of low-temperature hydrothermal systems within the lava section of the ocean crust. Experiments were conducted to study the exchange coefficient (D(Li/Ca)) and isotopic fractionation factor (α; 1000ln(α)=Δ) for lithium between inorganic calcite and an aqueous solution as a function of solution chemistry. These experiments show that, under the conditions used, D(Li/Ca) negatively correlates with solution H+/Ca2+ ratio (and the solution pH) and Δ positively correlates with solution pH. The change in D(Li/Ca) with solution chemistry is interpreted as indicating that Li is incorporated into calcite as LiHCO3, and hence depends on solution H+/Ca2+. A series of diffusion experiments were performed to test whether changes in pH led to changes in the aqueous Li speciation that would lead to changes in the relative diffusivity of the two Li-isotopes, but no such changes were observed. It is proposed that the change in Δ with changing solution pH may either reflect a kinetic or equilibrium isotope fractionation associated with changing solution chemistry. These results have important implications for interpreting the Li content of calcite that has undergone any diagenetic modification. The Li-content and isotopic composition of rocks altered by low-temperature, off-axis hydrothermal systems in the upper oceanic crust were studied to better understand the role of these systems in controlling the Li-isotopic composition of seawater. Results of a detailed study of DSDP Holes 417A, 417D and 418A from 119 Myr Western North Atlantic Ocean basin show that the Li content of the lavas decreases with depth in the upper ~30 m below sediments while the Li-isotopic composition increases from a low value and then does not show systematic variation in deeper sections. No evidence was found to support a role for a change in mineralogy of alteration products to explain the observed variation in Li composition of lavas. There is also no evidence for the modification of the composition of hydrothermal fluid due to a mixture with sediment pore-fluid. Simple one-dimensional fluid flow and fluid-rock reaction models also cannot explain the observed variation. Instead, a model of free-circulation of seawater through the upper few tens of meters of the lavas, and leakage of modified fluid into the deeper portion of the lava pile seems to explain the observed variations best. To investigate the role of low-temperature off-axis hydrothermal systems on the Li content and isotopic composition of seawater from the Cretaceous to modern era, five DSDP/ODP holes with crustal age spanning from 13.6 to 95 Myr were studied in combination with results from previous studies. Results suggest that the average amount of Li added to the upper oceanic crust decreases, while its average Li-isotopic composition increases, from the Cretaceous to the modern. The simplest explanation for these variations may be a decrease in Li concentration and an increase in Li-isotopic composition, of seawater over this time interval. / Graduate

We present 2-D numerical simulations of two phase flow in seafloor hydrothermal systems using the finite control volume numerical scheme FISHES. The FISHES code solves the coupled non-linear equations for mass, momentum, energy, and salt conservation in a NaCl-H2O fluid to model the seafloor hydrothermal processes. These simulations use homogeneous box geometries at a fixed seafloor pressure of 25 MPa with constant bottom temperature boundary conditions that represent a sub-axial magma chamber to explore the effects of permeability, maximum bottom temperature and system depth on the evolution of vent fluid temperature and salinity, and heat output. We also study the temporal and spatial variability in hydrothermal circulation. The two-phase simulation results show that permeability plays an important role in plume structure and heat output of hydrothermal systems, but it has little effect on vent fluid temperature and salinity, given the same bottom temperature. For some permeability values, multiple plumes can vent at the seafloor above the simulated magma chamber. Temporal variability of vent fluid temperature and salinity and the complexity of phase separation suggest that pressure and temperature conditions at the top of the axial magma chamber cannot be easily inferred from vent fluid temperature and salinity alone. Vapor and brine derived fluids can vent at the seafloor simultaneously, even from neighboring locations that are fed by the same plume. / Master of Science

Submitted by Geyciane Santos (geyciane_thamires@hotmail.com) on 2015-10-21T15:11:06Z No. of bitstreams: 1 Dissertação - Thaís Marcela Fernandes do Nascimento.pdf: 7663370 bytes, checksum: 78675054747a962a6b28925dad30eb5d (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-10-21T18:29:37Z (GMT) No. of bitstreams: 1 Dissertação - Thaís Marcela Fernandes do Nascimento.pdf: 7663370 bytes, checksum: 78675054747a962a6b28925dad30eb5d (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-10-21T18:39:05Z (GMT) No. of bitstreams: 1 Dissertação - Thaís Marcela Fernandes do Nascimento.pdf: 7663370 bytes, checksum: 78675054747a962a6b28925dad30eb5d (MD5) / Made available in DSpace on 2015-10-21T18:39:05Z (GMT). No. of bitstreams: 1 Dissertação - Thaís Marcela Fernandes do Nascimento.pdf: 7663370 bytes, checksum: 78675054747a962a6b28925dad30eb5d (MD5) Previous issue date: 2010-09-22 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / The Igarapé Maneiga W-Sn deposit is composed of a granitic intrusive stock in Paleoproterozoic basement rocks (Jamari Complex) and covered by alluvial-colluvial sediments. The stock granite is formed by two petrographic types: biotite-alkali feldspar granite and topaz-albite granite. The precursor stage magmatic mineralization is attributed to the topaz-albite granite, which displays geochemical signature peraluminous, subalkaline with medium K2O and REE distribution in concave pattern, with negative anomalies in Eu (Eu/EuN = 0.07) and with fractionation absence between LREE and HREE ([La /Yb]N = 0.8). The W-Sn ore (wolframite and cassiterite) is associated with greisens, breccia and veins-veinlets systems. In the greisens the wolframite and cassiterira crystals occur associated with quartz, topaz, Li-mica, fluorite, sphalerite, pyrite, marcasite, pyrrhotite, galena, chalcopyrite, molybdenite, bismuthinite, siderite, phengite, monazite, xenotime and hematite. The ore in the breccia occurs distributed so widespread and irregular, while in the veins-veinlets system can be identified at least two generations, usually surrounded by Li-mica crystals arrangement in comb and stocksheider structures, with the ore occupying both the edges as the central parts associated with pyrite, chalcopyrite, galena, molybdenite, bismuthinite and siderite. The preliminary study about fluid inclusions in greisens has recognized two fluid systems: H2O-NaCl and H2O-CO2-NaCl. The system H2O-NaCl is dominant, which has low density (0.8 to 0.9 g/cm3) and salinity between 0.1 to 6.7 wt% NaCl, while the system H2O-CO2-NaCl has salinity 9-9.8 wt% NaCl. Overall, the main temperature range of total homogenization of the fluid system is between 250 and 300º C. Analyses of oxygen (δ18O) and sulfur (δ34S) isotopes show that the ore hydrothermal fluid is likely magmatic, whose temperature isotopic to crystallization of the mineral pair wolframite-quartz is between 220 and 270° C, consistent with the preliminary data from fluid inclusions studies. The 40Ar/39Ar ages obtained for the Li-micas from greisens determine value of 988 ± 5 Ma, interpreted as the age-cooling of the system hydrothermal, which occurred around 350° C. The geological evolution proposed to the Igarapé Manteiga W-Sn deposit involved in the late-stage of crystallization of the topaz-albite granite magmatic phase, a segregation process of two stages: magmatic and hydrothermal. The hydrothermal stage driven by volatile adduced vast majority of incompatible elements, lodging at the interface granite and host-rocks. The tension in the hall host- rock provided a burst relieving of tension and generating fractures that have spread over the granite dome, producing hydrothermal breccia and a second generation of veins-veinlets systems, lowering the temperature in the hydrothermal fluid and provided the precipitation of ore-metallic content. This process took place under a temperature range 200-300º C, and confining pressure estimated at between 0.5-1.5 kbar and about of 988 ± 5 Ma. / O depósito de W-Sn Igarapé Manteiga é formado por um stock granítico intrusivo em rochas do embasamento paleoproterozóico (Complexo Jamari) e encoberto por sedimentos colúvio-aluvionares sub-atuais. O stock granítico é composto pelos tipos petrográficos biotita-álcali feldspato granito e topázio-albita granito. A fase magmática precursora da mineralização é atribuída ao topázio-albita granito, a qual exibe caráter peraluminoso, subalcalina de médio K2O e padrão côncavo de distribuição dos ETR, com anomalia negativa em Eu (Eu/EuN = 0,07) e ausência de fracionamento dos ETR leves em direção aos ERT pesados ([La/Yb]N = 0,8). A mineralização de W-Sn (wolframita e cassiterita) está associada a greisens, brechas e sistemas de veios e vênulas. Nos greisens, wolframita e cassiterira ocorrem associados a quartzo, topázio, mica-Li, fluorita, esfalerita, pirita, marcassita, pirrotita, galena, calcopirita, molibidenita, bismutinita, siderita, fengita (mica branca), monazita, xenotímio e hematita. Na brecha a mineralização ocorre disseminada e/ou formando fragmentos de tamanhos variados distribuídos de modo caótico. No sistema de veios e vênulas é possível identificar, pelo menos, duas gerações. Esse sistema é normalmente contornado por cristais de mica-Li em arranjo do tipo comb e stocksheider, com a mineralização ocupando tanto as bordas como as partes centrais, associada à pirita, calcopirita, galena, molibidenita, bismutinida e siderita. Estudo preliminar sobre inclusões fluidas nos greisens demonstram a existência de dois sistemas fluidos: H2O-NaCl e H2O-CO2-NaCl. O sistema H2O-NaCl é dominante, o qual apresenta densidade baixa (0,8 a 0,9 g/cm3) e salinidade entre 0,1 a 6,7 wt%NaCl, enquanto que o sistema H2O-CO2-NaCl apresenta salinidade entre 9 e 9,8 wt%NaCl. No geral, o principal intervalo de temperatura de homogeneização total do sistema fluido está entre 250 e 300º C. Análises de isótopos de oxigênio (δ18O) e enxofre (δ34S) demonstram que o fluido hidrotermal responsável pela mineralização é de natureza magmática, cujas temperaturas isotópicas de cristalização do par mineral wolframita-quartzo está entre 220 e 270º C, compatível com os dados preliminares de inclusões fluidas. A idade 40Ar/39Ar do obtida para micas-Li de greisens, determinam valor de 988 ± 5 Ma, interpretado como a idade de resfriamento desse sistema hidrotrermal, a qual ocorreu por volta de 350º C. A evolução do depósito de W-Sn Igarapé Manteiga envolveu no final da cristalização da fase magmática topázio-albita granito um processo de separação das fases magmática e hidrotermal, que se tornaram imiscíveis. A fase hidrotermal impulsionada pelos voláteis carreou grande maioria dos elementos incompatíveis, alojando-se na interface cúpula granítica - rocha encaixante. A tensão sob a carapaça de rocha encaixante proporcionou a ruptura da mesma, aliviando a tensão e gerando fraturas de extensão que se propagaram acima da cúpula granítica, produzindo brechas hidrotermais e uma segunda geração de veios e vênulas, abaixamento da temperatura no sistema hidrotermal e proporcionou a precipitação do conteúdo metálico. Tal processo ocorreu sob um intervalo de temperatura entre 200º e 300º C, sob pressão confinante estimada entre 0,5 e 1,5 kbar e ha cerca de 988 ± 5 Ma atrás.

Mid-ocean ridge hydrothermal systems play an important role in the cycling of energy and mass between the solid earth and oceans. The on-axis low-temperature diffuse fluids (temperature lower than ~100 °C) carry ~90% of the on-axis heat fluxes, but diffuse fluids generation is poorly constrained. This study uses the abundance of the chalcophile elements, which form metal-sulphides in the rock record, to test models for diffuse fluids generation. These include mixing between seawater and high-temperature hydrothermal fluids and conductive cooling of high- temperature hydrothermal fluids. This thesis determined the concentrations of the elements of interest (As, Mo, Ag, Cd, Sn, and Tl) in geological reference materials using standard addition method in ICP-MS. These values were used to calibrate the analysis of samples from Pito Deep to trace the abundance of these elements within the upper oceanic crust. The results show that the Zn, Cu, As, Ag, Cd, Tl, and Pb are generally depleted in sheeted dikes and enriched in the lava unit and/or the transition zone, which is consistent with previous studies on fast-spreading EPR crust at Hole 504B, Hess Deep and Hole 1256D. The enrichment of these elements in the lava unit and/or the transition zone suggests that cooling high-temperature hydrothermal fluids to form diffuse fluids occurred in this iii iv area of the oceanic crust. Molybdenum and Sb are added into all units of the crust by recharging seawater. The concentrations of chalcophile elements in diffuse fluids were calculated by a mass balance. The results of this study favored a diffuse fluids generation model that involves mixing of seawater and high-temperature hydrothermal fluids. Results also show that the observed concentrations of Mo and Sb requires extra input source besides recharging seawater and oceanic crust, possibly particulates in seawater. / Graduate / juliatian2013@gmail.com

Neste trabalho estudamos um controlador denominado rastreador linear quadrático (RLQ) com custo médio de longo prazo (CMLP) para sistemas lineares com saltos markovianos (SLSM). Mostramos que o conceito de detetabilidade uniforme, juntamente com a hipótese de que o regulador linear quadrático associado ao RLQ tenha custo uniformemente limitado, são suficientes para que o controle obtido seja estabilizante em um certo sentido. A partir deste resultado, e considerando as mesmas hipóteses, demonstramos a existência do CMLP. Com isto, estendemos os resultados dispostos na literatura desde que consideramos um sistema variante no tempo e uma estrutura mais geral para a cadeia deMarkov. Além disto, avaliamos a aplicação deste controlador no planejamento da operação de um sistema hidrotérmico. Para isto, utilizamos o sistema de usinas do rio São Francisco, em dois casos de estudo, para comparar o desempenho do controlador estudado em relação à solução ótima para o problema, encontrada com o uso da programação dinâmica estocástica, e em relação à solução obtida via programação dinâmica determinística. Os resultados sugerem que o RLQ pode representar uma alternativa interessante para o problema de planejamento hidrotérmico / In the present work we study the reference tracking controller (RTC) for the long run average cost (LRAC) problem for Markov jump linear systems. We show that uniform detectability and an hypothesis that the linear quadratic regulator associated with the RTC has uniformly bounded cost, together, are sufficient conditions for the obtained control be exponentially stabilizing in a certain sense. This result allows us to demonstrate the existence of the LTAC under the same hypotheses. The results can be regarded as an extension of previous works, since we have considered a more general framework with time-varying systems and quite general Markov chains. As an applicatioin, we consider the operational planning of hydrothermal systems. We have considered some power plants of the Sao Francisco river, in two different scenarios, and we have compared the performances of the RTC and standard controls obtained by deterministic and stochastic dynamic programming, indicating that the RTC may be an interesting alternative for the hydrothermal planning problem

Este trabalho aborda o problema de modelagem de séries de vazões afluentes aos aproveitamentos hidrelétricos. A previsão de vazão natural fluvial é realizada semanalmente para 158 usinas hidrelétricas do Sistema Interligado Nacional (SIN), pois trata-se de insumo fundamental para o planejamento e operação do sistema elétrico brasileiro. Diversos modelos são utilizados na determinação destas previsões, entre os quais podem ser citados os modelos físicos, os estatísticos e aqueles que aplicam sistemas inteligentes. Apesar de contínuos aprimoramentos terem sido incorporados ao processo de previsão de vazão, existem alguns aproveitamentos hidrelétricos para os quais os resultados de estimação têm apresentado grandes desvios. Neste contexto, com a motivação de se obter uma resposta acurada, investigam-se os sistemas fuzzy como modelos concorrentes aplicados à previsão de vazões semanais. O objetivo do trabalho é reduzir os erros de estimação para uma usina piloto, incorporando à previsão de vazão os dados de precipitação. Para a construção da série histórica de precipitação média da bacia hidrográfica, fez-se uma exaustiva pesquisa por estações pluviométricas, seguida por tratamento de dados de medição e método de interpolação. Ao final do trabalho, é apresentada uma análise comparativa entre os resultados obtidos com o Modelo Autorregressivo Periódico (PAR) e o sistema de inferência fuzzy. Com base no desempenho observado, superior ao modelo autorregressivo, comprova-se a adequação do modelo proposto para a modelagem do processo hidrológico. / This work addresses the modelling problem of hydropower plants reservoir streamflow series. The natural streamflow forecasting for 157 hydroelectric power plants of the National Interconnected System - NIS is updated on a weekly basis, which is an essential input for the planning and operation of the Brazilian Electric Power System. Several models are used to determine this prediction, such as physicals, statisticals and the ones that use intelligent systems. Despite the improvements to natural streamflow forecasting, substantial deviation has been found for the expected results of some hydropower plants. Highlighted the importance of this variable, fuzzy systems applied to weekly streamflows forecasts will be investigated as alternative models, in order to obtain better results. The purpose of this work is to reduce the estimation errors for a pilot hydropower plant, incorporating precipitation data into the forecast. Therefore, an exhaustive research to acquire data from hydrometeorological stations was conducted. After being treated, a variable selection method was applied to the data, defining the most relevant input variables for the prediction model. At the end, a comparative analysis shows that the fuzzy model presents a better performance than the periodic autoregressive model used by ONS to plan the operation of the electric power system.

Este trabalho aborda o problema de modelagem de séries de vazões afluentes aos aproveitamentos hidrelétricos. A previsão de vazão natural fluvial é realizada semanalmente para 158 usinas hidrelétricas do Sistema Interligado Nacional (SIN), pois trata-se de insumo fundamental para o planejamento e operação do sistema elétrico brasileiro. Diversos modelos são utilizados na determinação destas previsões, entre os quais podem ser citados os modelos físicos, os estatísticos e aqueles que aplicam sistemas inteligentes. Apesar de contínuos aprimoramentos terem sido incorporados ao processo de previsão de vazão, existem alguns aproveitamentos hidrelétricos para os quais os resultados de estimação têm apresentado grandes desvios. Neste contexto, com a motivação de se obter uma resposta acurada, investigam-se os sistemas fuzzy como modelos concorrentes aplicados à previsão de vazões semanais. O objetivo do trabalho é reduzir os erros de estimação para uma usina piloto, incorporando à previsão de vazão os dados de precipitação. Para a construção da série histórica de precipitação média da bacia hidrográfica, fez-se uma exaustiva pesquisa por estações pluviométricas, seguida por tratamento de dados de medição e método de interpolação. Ao final do trabalho, é apresentada uma análise comparativa entre os resultados obtidos com o Modelo Autorregressivo Periódico (PAR) e o sistema de inferência fuzzy. Com base no desempenho observado, superior ao modelo autorregressivo, comprova-se a adequação do modelo proposto para a modelagem do processo hidrológico. / This work addresses the modelling problem of hydropower plants reservoir streamflow series. The natural streamflow forecasting for 157 hydroelectric power plants of the National Interconnected System - NIS is updated on a weekly basis, which is an essential input for the planning and operation of the Brazilian Electric Power System. Several models are used to determine this prediction, such as physicals, statisticals and the ones that use intelligent systems. Despite the improvements to natural streamflow forecasting, substantial deviation has been found for the expected results of some hydropower plants. Highlighted the importance of this variable, fuzzy systems applied to weekly streamflows forecasts will be investigated as alternative models, in order to obtain better results. The purpose of this work is to reduce the estimation errors for a pilot hydropower plant, incorporating precipitation data into the forecast. Therefore, an exhaustive research to acquire data from hydrometeorological stations was conducted. After being treated, a variable selection method was applied to the data, defining the most relevant input variables for the prediction model. At the end, a comparative analysis shows that the fuzzy model presents a better performance than the periodic autoregressive model used by ONS to plan the operation of the electric power system.

Les Champs Phlégréens, situés dans la métropole napolitaine (Italie du sud), forment l’une des plus grandes structures volcaniques au monde. Depuis 1950, ce complexe volcanique manifeste un regain d’activité, qui s’est amplifié au cours de la dernière décennie. Cette accélération s’exprime au travers d’une intensification de la sismicité, de la déformation du sol ainsi qu’une extension de la zone de dégazage. L’ensemble des récentes études s’accorde à dire que le système s’achemine actuellement vers un point critique, sans toutefois pouvoir préciser quand et où pourrait avoir lieu une éventuelle éruption. Cette difficulté à prédire l’état réel du système est principalement associée à la présence d’un système hydrothermal relativement développé. Aux Champs Phlégréens, il est en effet difficile de déconvoluer les signaux provenant du forçage magmatique de ceux résultant de la réponse hydrothermale. L’objectif de cette thèse est donc d’améliorer les connaissances actuelles du système hydrothermal superficiel du volcan de la Solfatara, lieu où se concentre actuellement la reprise d’activité. Pour cela, une approche multidisciplinaire a été menée en deux phases : l’imagerie géophysique du volcan puis la modélisation de son système hydrothermal.La tomographie haute-résolution de résistivité électrique 3-D du cratère a permis de reconnaître les principales formations géologiques et leurs connexions avec les structures et écoulements hydrothermaux. L’interprétation du modèle de résistivité électrique a été réalisée grâce à un ensemble de mesures superficielles complémentaires : flux de CO2, température, potentiel spontané, capacité d’échange cationique et pH du sol. Deux panaches à dominante liquide ont été identifiés : la mare de boue de la Fangaia et la fumerole de Pisciarelli. À la Fangaia, une étude conjointe des modèles de résistivité électrique et de vitesses du sous-sol (obtenues par l’INGV) établit la présence de forts gradients, à la frontière entre panache hydrothermal et zone de dégazage diffus. Au niveau du principal secteur fumerolien, le modèle de résistivité électrique et la localisation des sources acoustiques révèlent clairement l’anatomie d’une zone fumerolienne. Deux conduits séparés, saturés en gaz, alimentent les fumeroles de Bocca Grande et de Bocca Nuova, depuis un même réservoir de gaz situé à ~50 mètres de profondeur. L’intense dégazage diffus produit à proximité de ces fumeroles occasionne la condensation de vapeur. Le modèle de résistivité électrique met en évidence la circulation souterraine de cet important volume d’eau, canalisée à l’intérieur d’une zone fracturée.En utilisant l’ensemble de ces informations structurelles, un modèle thermodynamique des écoulements multiphasiques de la principale zone fumerolienne a été réalisé. Ce modèle reproduit fidèlement les observables des fumeroles : température, flux et rapport CO2/H2O. Il valide l’imagerie géophysique et confirme l’interaction entre la circulation d’eau de condensation et l’un des conduits fumeroliens. Ainsi, cette simulation explique, pour la première fois par un effet d’interaction superficiel, les différentes signatures géochimiques des deux fumeroles : Bocca Nuova et Bocca Grande. L’approche multidisciplinaire, employée dans cette thèse, constitue une nouvelle étape vers une meilleure connaissance des interactions hydrothermales. Celles-ci doivent être prise en compte dans l’objectif de réaliser des modélisations dynamiques précises permettant d’appréhender in fine l’état réel du système volcanique. / The Campi Flegrei caldera is located in the metropolitan area of Naples (Italy), and it is one of the largest volcanic systems on Earth. Since 1950, this volcanic complex shows significant unrest, which accelerated over the last decade with a rise in the seismic activity, ground deformation, and the extent of the degassing area. Recent studies indicate that the volcanic system is potentially moving toward a critical state, although their authors remain unable to point out when and where a possible eruption could take place. The difficulty of predicting the real volcanic state is here mainly related to the hydrothermal system. Indeed, at the Campi Flegrei, it is difficult to separate the magmatic input signal from the hydrothermal response. Hence, the aim of this thesis is to improve our knowledge on the shallow hydrothermal system of the Solfatara volcano, where most of the renewal activity takes place. A multidisciplinary approach has been performed in two steps: first a geophysical imagery of the volcano and second the modeling of its hydrothermal system.The 3-D electrical resistivity tomography of the crater allows to recognize the main geological units, and their connection with hydrothermal fluid flow features. The interpretation of the resistivity model has been realized thanks to numerous soil complementary measurements: CO2 flux, temperature, self-potential, Cation Exchange Capacity and pH. We identify two liquid-dominated plumes: the Fangaia mud pool and the Pisciarelli fumarole. In the Fangaia area, the comparison between electrical resistivity and velocity models reveals strong gradients related to a sharp transition at the border between the hydrothermal plume and the high diffuse degassing region. Combining electrical resistivity model with hydrothermal tremor sources localization reveal the anatomy of the main fumarolic area. Two separated conduits, gas-saturated, feed the two fumaroles Bocca Grande and Bocca Nuova. These conduits originate from the same gas reservoir located 60 m below the surface. The intense degassing activity, produced in the vicinity of fumaroles, creates large amounts of vapor condensation. The resistivity model reveals this condensate circulation, within a fractured area.All these results are incorporated into a multiphase flow model of the main fumarolic area. The simulation accurately reproduces the fumaroles observables: temperature, flux and CO2/H2O ratio. The model validates the geophysical imagery and confirms the interaction between Bocca Nuova fumarolic conduit and the condensate flow. Hence, this simulation explains for the first time the distinct geochemical signature of the two fumaroles due to a shallow water-interaction. The multidisciplinary approach performed in this thesis constitutes a new step toward a better understanding of hydrothermal interactions. Those phenomena have to be taken into account in order to perform dynamic modelling, and thus apprehend the real state of the volcanic system.