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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Hydrogeological characterization of watersheds in the semi arid baiano using GIS techniques. / CaracterizaÃÃo hidrogeolÃgica de bacias hidrogrÃficas do semiÃrido baiano atravÃs de tÃcnicas de geoprocessamento

Edivam Josà da Silva 10 February 2009 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / For the adoption of water resources management in dry regions where water availability is limited, knowledge of the different processes of the hydrological cycle is needed, especially the precipitation and flow. Therefore, techniques of GIS are essential in studies of hydrological modeling. The study on maximum flow in a watershed is important because the same act on soil erosion, flooding in urban and rural areas, hydraulic works, among others. The Salitre basin is located in the State of Bahia, Brazil, and its Pacui sub-basin is fully inserted in the Campo Formoso municipio. With a drainage area of 987.74 km2, it is one of the main drainage sub-basin of Salitre river. Hence, the objective of this work was to characterize physiographically the Pacui sub-basin, estimate peak flow by USDA-SCS and Dooge methods, and estimate the hourly evapotranspiration in the sub-basin using the algorithm SEBAL (Surface Energy Balance Algorithms for Land) and images from Landsat 7 - ETM. The Global Mapper software was used for the analysis of land numerical model (SRTM). The ENVI 4.3 software was used for georeferencing of data from topographic maps of SUDENE, and the Arcmap 9.2 software was used for watershed delineation. The time of concentration was determined by USDA and Dooge methods. To determine the radiation balance images from the INPE (National Institute for Space Research) were used and processed by Arcmap  software, within algorithm SEBAL was developed. The basin presented low slope and then tends to reduce the flood peak because of the low speed runoff. ArcHidro proved to be an effective tool in the delineation of river basins and the generation of drainage network and compared with those obtained by maps from SUDENE. The algorithm SEBAL proved to be an agile and efficient tool in evapotranspiration estimation. The use of SRTM provided information of parameters as surface albedo, incident long-wave and shortwave radiations, pixel to pixel. Lower rates of hourly evapotranspiration (<0.15 mm.h-1) were recorded in areas of exposed soils, and higher rates were found in irrigated areas and vegetation, expressing the sensitivity of algorithm SEBAL on evapotranspiration estimation in watershed scale. / Para a adoÃÃo de uma gestÃo adequada dos recursos hÃdricos tendo como unidade de planejamento a bacia hidrogrÃfica, o conhecimento dos diferentes processos do ciclo hidrolÃgico se faz necessÃrio, notadamente da precipitaÃÃo, do escoamento e da evapotranspiraÃÃo. Portanto, tÃcnicas de geoprocessamento sÃo imprescindÃveis nos estudos de modelagem hidrolÃgica a nÃvel de bacias hidrogrÃficas. O estudo sobre o escoamento superficial, em uma bacia hidrogrÃfica à importante pelo fato do mesmo atuar sobre a erosÃo do solo, inundaÃÃes em Ãreas rurais e urbanas, obras hidrÃulicas, entre outros. A bacia do rio Salitre esta localizada no Estado da Bahia, e a sub-bacia do rio Pacui esta inserida totalmente no municÃpio de Campo Formoso, com Ãrea de drenagem de 987,74 km2, constituindo umas das principais subbacias de drenagem para o rio Salitre. Nesse contexto, objetivou-se caracterizar fisiograficamente a sub-bacia rio Pacui e bacia do rio Salitre, analisar a estimativa de vazÃo de pico pelos mÃtodos de SCS-USDA e de Dooge, e estimar a evapotranspiraÃÃo horÃria na bacia do rio Pacui utilizando-se o algoritmo SEBAL (Surface Energy Balance Algorithms for Land) e imagens do Landsat 7 â ETM. Utilizou-se os softwares Global Mapper, para anÃlises do modelo numÃrico do terreno (SRTM), ENVI 4.3, para georeferenciamento dos dados tendo como base as cartas topogrÃficas da SUDENE e do software ArcMap 9.2 para delimitaÃÃo automÃtica de bacias. O tempo de concentraÃÃo foi determinado pelos mÃtodos USDA e de Dooge. Para determinar o balanÃo de radiaÃÃo utilizou-se de imagem da regiÃo obtida junto ao INPE (Instituto Nacional de Pesquisas Espaciais) e processadas na ferramenta Ãlgebra de mapa no software ArcMap onde foi desenvolvido o algoritmo SEBAL. A bacia apresenta baixa declividade, portanto tende a uma reduÃÃo dos picos de descargas devido à baixa velocidade de escoamento superficial. A extensÃo ArcHidro mostrou-se uma ferramenta eficaz na delimitaÃÃo de bacias e na geraÃÃo de rede drenagem, comparando com as obtidas pelas cartas da DSG/SUDENE. O algoritmo SEBAL mostrou-se uma ferramenta Ãgil e eficiente na estimativa da evapotranspiraÃÃo. A utilizaÃÃo do SRTM proporcionou ganhos de informaÃÃes nos parÃmetros albedo da superfÃcie, radiaÃÃo de ondas longas incidente, radiaÃÃo de onda curtas incidente, pixel a pixel. Menores taxas de evapotranspiraÃÃo horÃria (< 0,15 mm.h-1) foram registradas em Ãreas de solos expostos e as maiores nas Ãreas irrigadas e vegetaÃÃo no geral, expressando a sensibilidade do algoritmo SEBAL na estimativa da evapotranspiraÃÃo em escala de bacias hidrogrÃficas.
12

Estudo sobre a sensibilidade dos parâmetros do método SCS na determinação de hidrogramas de cheia em bacias urbanas / Study on the SCS method parameter sensitivity in determination of flood hydrographs in urban basin

Paloma Fernandes Paulino 30 September 2014 (has links)
Para simular o comportamento da bacia hidrográfica diante de eventos chuvosos e, a partir da quantificação das vazões de cheias, encontrar soluções para os problemas causados pelas enchentes, é essencial a utilização de modelos de transformação chuva-vazão. Há diferentes métodos para o cálculo do deflúvio superficial ou precipitação excedente para uma dada bacia hidrográfica. Entre estes, um dos mais utilizados pela comunidade técnica é o método desenvolvido pelo Departamento de Conservação do Solo norte-americano: SCS (Soil Conservation Service, atual National Resources Conservation Service), aplicável principalmente quando não se dispõe de séries históricas de dados hidrológicos. A utilização deste método depende da seleção do parâmetro CN (Curve Number), que por sua vez requer o conhecimento das características da bacia hidrográfica em estudo, como: tipos de solo, cobertura vegetal, uso da terra, teor de umidade do solo anterior à chuva. A partir da precipitação excedente total do evento chuvoso, para se construir um hidrograma de cheia, é necessário distribuir a chuva ao longo do tempo, ou seja, construir o hietograma da precipitação excedente. O SCS também propõe um método baseado no hidrograma unitário triangular sintético para gerar o hidrograma de cheia a partir de um certo hietograma. O parâmetro básico para se obter esse hidrograma sintético é o tempo de concentração da bacia hidrográfica (tc). Para a determinação deste parâmetro existem diversas fórmulas empíricas baseadas nas características físicas da bacia hidrográfica, uma vez que a sua determinação numa bacia sem dados hidrométricos torna-se impossível. Deste modo, para uma estimativa coerente do tc, é necessário avaliar para cada caso a ser estudado a fórmula mais adequada e os dados disponíveis. Neste sentido, o presente estudo tem como objetivo analisar a sensibilidade do método SCS em relação à classificação do uso e ocupação do solo e ao tempo de concentração, a partir de aplicação deste para a bacia do córrego do Mineirinho situada em São Carlos, SP. A análise da sensibilidade em relação ao CN foi realizada através da comparação dos resultados produzidos utilizando-se mapas de classificação dos usos do solo, produzidos a partir de imagens de satélite de alta resolução, as quais não são disponibilizadas gratuitamente, e imagens gratuitas de baixa resolução. Em relação ao tempo de concentração, foram analisadas e comparadas as diversas fórmulas disponíveis para sua determinação para uma bacia urbana. Outro aspecto estudado foi a distribuição temporal da chuva crítica. Existem diversos métodos indicados na literatura, como o dos blocos alternados, Huff e Bureau of Reclamation. Analisou-se o efeito que cada método produz nos hidrogramas de cheia resultantes. O método SCS apresenta-se bastante sensível em relação aos três parâmetros analisados. As diferenças entre os valores de CN, obtidos a partir das imagens de alta e baixa resolução, foram as que resultaram em maiores diferenças nas vazões de pico. A imagem de baixa resolução tende a subestimar as vazões de pico. Os métodos de distribuição temporal da chuva como Blocos Alternados e Huff 2°. Quartil, apesar serem métodos diferentes, produziram resultados semelhantes. / To simulate the behavior of the basin before rain events and, from the quantification of flow of floods, find solutions to the problems caused by flooding, it is essential the use of models of processing rain-flow. There are different methods for calculating the surface runoff or excess rainfall for a given basin. Among these, one of the most used by technical community is the method developed by the Department of Soil Conservation American: SCS (Soil Conservation Service, current National Resources Conservation Service), mainly applicable when there is no historical series of data hydrological. The use of this method is dependent on the selection of the parameter CN (Curve Number), which in turn requires the knowledge of the characteristics of the basin under study, such as: soil types, vegetation cover, land use, soil moisture content prior to the rain. From the total surplus precipitation of rain event, in order to build a hydrograph, it is necessary to distribute the rain over time, i.e. build the hyetogram of excess rainfall. The SCS also proposes a method based on unit hydrograph triangular synthetic. The basic parameter to obtain this synthetic hydrograph is the time of concentration of the basin (tc). For the determination of this parameter there are several empirical formulas based on the physical characteristics of the basin, since its determination in a basin without hydrometrical data becomes impossible. Thus, for a consistent estimate of tc, it is necessary to evaluate the most suitable formula and the data available for each case to be considered. In this sense, the aim of the present study is to analyze the sensitivity of the SCS method in relation to the classification of the use and occupation of the soil and the time of concentration, from application of this model to the basin of the Mineirinho located in São Carlos, SP. The sensitivity analysis in relation to the CN was performed through the comparison of the results produced using maps of classification of soil uses, produced from high-resolution satellite images, which are not made available for free, and free images of low resolution. In relation to the time of concentration, the various formulas available were analyzed and compared for its determination to an urban basin. Another aspect studied, was the temporal distribution of critical rainfall. There are several methods given in the literature, such as the Alternating Block, Huff and Bureau of Reclamation. This study aimed to analyze the effect each method produces in the resulting flood hydrographs. The SCS method is quite sensitive in relation to the three parameters analyzed. The differences between the values of CN, obtained from the images of high and low resolution, were the ones that resulted in greater differences in flow of peak. The low resolution image tends to underestimate the flow of peak. The methods of temporal distribution of rainfall as Alternating Block and Huff 2°. Quartil, despite being different methods, produced similar results.
13

Investigation on the Mechanisms of Elastomechanical Behavior of Resilin

Khandaker, Md Shahriar K. 08 December 2015 (has links)
Resilin is a disordered elastomeric protein and can be found in specialized regions of insect cuticles. Its protein sequence, functions and dynamic mechanical properties vary substantially across the species. Resilin can operate across the frequency range from 5 Hz for locomotion to 13 kHz for sound production. To understand the functions of different exons of resilin, we synthesize recombinant resilin-like hydrogels from different exons, and investigate the water content and dynamic mechanical properties, along with estimating surface energies relevant for adhesion. The recombinant resilin-like hydrogel has 80wt% water and does not show any sign of tack even though it satisfies the Dahlquist criterion. Finally, doubly shifted dynamic moduli master curves are developed by applying the time-temperature concentration superposition principle (TTCSP), and compared to results obtained with natural resilin from locusts, dragonflies and cockroaches. The resulting master curves show that the synthetic resilin undergoes a prominent transition, though the responsible mechanism is unclear. Possible explanations for the significant increase in modulus include the formation of intramolecular hydrogen bonds, altered structural organization, or passing through a glass transition, all of which have been reported in the literature for polymeric materials. Results show that in nature, resilin operates at a much lower frequency than this glass transition frequency at room temperature. Moreover, recombinant resilins from different clones have comparable resilience with natural resilin, though the modulus is around 1.5 decades lower. Results from the clones with and without chitin binding domains (ChBD) indicate that the transition for the clone without ChBD occurs at lower frequencies than for those with the ChBD, perhaps due to the disordered nature of the clone without ChBD. Atomistic molecular modeling is applied on the repetitive motifs of resilin and different elastomeric proteins to better understand the relationship between elastomeric behavior and amino acid sequences. Results show that the motifs form a favorable bent conformation, likely enabled by glycine's lack of steric hindrance and held in place through intramolecular hydrogen bonds. During Steered Molecular Dynamic (SMD) pulling of these motifs, the hydrogen bonds break and they reform again when the peptides are released to move freely, returning to similar bent conformations. The transition seen in the master curves of recombinant resilins might be due to either these intramolecular hydrogen bonds or to glass transition behavior, though evidence indicates that the transition probably due to the glass transition. What we learned from the synthesized recombinant resilin and simulating the repetitive motifs of resilin may be applicable to the biology and mechanics of other elastomeric biomaterials, and may provide deeper understanding of their unique properties. / Ph. D.

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