Uno de los problemas más importantes en el mundo es la erosión costera. Alrededor del 70% de las playas de arena están sufriendo erosión. Las costas representan en la mayoría de los casos las zonas turísticas y por lo tanto la prevención de la erosión es una necesidad común. Generalmente, para hacer frente a este problema se realizan regeneraciones y/o obras de defensa costera, lo que conduce a costos económicos. En el caso concreto de España, el turismo es una importante fuente de ingresos, representando entorno al 10,9% del Producto Interior Bruto. En consecuencia, la prevención de la erosión del litoral español es necesaria con el fin de mantener esta entrada económica. Para que la evaluación y comprobación de los proyectos de regeneración de playas o de defensa costera (entre otras) sean eficaces, son necesarios métodos cada vez más precisos y fiables. Es por ello que se requiere habilidades de predicción con las que se pueda cuantificar los errores cometidos para así evaluar los posibles costes relacionados a ese error. En este sentido los modelos lineales, no lineales, redes neuronales artificiales o modelos numéricos pueden desempeñar un papel fundamental para su utilización en los proyectos de regeneración de playas. La presente Tesis Doctoral estudia las playas tanto de arena como de grava que se encuentran en el levante español, concretamente en las provincias de Valencia, Alicante y Murcia, con el objetivo de clasificar los diferentes tipos de playas y modelar el perfil transversal de las playas. En primer lugar, se realiza una clasificación de las playas en nueve tipos dependiendo de la morfología y la proporción y distribución de la arena y la grava en cada playa (Capítulo 1). Para ello se comparan tres métodos: el análisis discriminante, las redes neuronales artificiales y el método SVM (Support Vector Machine). En segundo lugar se modeliza el perfil transversal real de las playas de arena utilizando redes neuronales artificiales, empleando para ello el menor número de variables posibles y que sean fáciles de obtener (Capítulo 2). Para ello se determina la arquitectura óptima de la red neuronal y se comparan varias redes con diferentes parámetros de entrada. Una vez obtenida la red neuronal para el perfil de la playa se genera otra red neuronal siguiendo la misma metodología para determinar los puntos característicos de las barras que se pueden encontrar a lo largo del perfil (Capítulo 3). Por otro lado, se estudia el perfil transversal de las playas de grava. El perfil de estas playas se divide en tres zonas: playa seca, perfil sumergido hasta la profundidad de cierre o el inicio de la pradera de Posidonia oceanica, y el perfil dentro de la pradera. Estos perfiles se ajustan empleando diferentes funciones matemáticas: potenciales, exponenciales, y racionales, seleccionando la que mejor ajusta al perfil real en cada una de las tres zonas (Capítulo 4). Finalmente, se modelizan los parámetros que definen la función potencial que describe el perfil de equilibrio que mejor se ajusta al perfil sumergido de las playas de grava (Capítulo 5). En este caso se compara el funcionamiento de los métodos lineales y los numéricos, generando diferentes modelos en los que se tiene en cuenta o no el tipo de playa en la que se encuentra el perfil. Además se considera para ello variables que no se vean influidas por la constante variación que sufren las playas de grava debido al constante movimiento de la berma y el sedimento por el impacto del oleaje. Con todo esto, se pretende obtener nuevos modelos que nos permitan diseñar futuras regeneraciones empleando los volúmenes de material precisos, sin cometer grandes errores que supongan un coste en exceso. Pues en la actualidad, en España, se emplean formulaciones y/o modelos obtenidos a partir de ensayos en canal u obtenidas empíricamente en zonas con características muy diferentes, y que por lo tanto no contemplan el factor local. Así, se pretende que las nuevas herramientas que se proponen nos permitirán comprobar el funcionamiento futuro en el caso de que algunos de los factores implicados en la clasificación de la playa o en el modelado del perfil transversal se vean modificados, bien por la acción del hombre o por cambios naturales, de manera que sirvan de apoyo para el ingeniero costero a la hora de calcular una regeneración.

Les écosystèmes marins côtiers subissent de nombreuses perturbations naturelles et anthropiques. Dans le contexte socio-économique actuel, mieux comprendre le fonctionnement et transfert des contaminants dans ces écosystèmes est primordial. L’étude du transfert de la matière organique et des contaminants aux interfaces, constitue un enjeu crucial. Les principaux objectifs sont de caractériser l’ichtyofaune des herbiers de posidonie et comprendre les relations trophiques ; d’établir les niveaux et variabilité spatiale de la contamination en éléments traces ETs et polluants organiques persistants POPs dans les compartiments de l’écosystème ; et d’identifier les sources et les processus influençant les niveaux de contamination le long du réseau trophique à Marseille et Hyères. La caractérisation du peuplement de poissons et des relations trophiques au sein de l’écosystème est nécessaire pour comprendre les niveaux de contamination. Chez les poissons, le phénomène de bioaccumulation des ETs est difficile à mettre en évidence, excepté pour le mercure. L’influence du régime alimentaire, taille et besoins physiologiques et métaboliques est manifeste. La grande stabilité et la rémanence des POPs leur confèrent des propriétés de bioconcentration et de bioamplification importantes. Les concentrations en contaminants mesurées, ainsi que la détection de pesticides toxiques interdits, attestent de la nécessité de considérer cette pollution avec attention, plus forte à Marseille. / The marine ecosystems undergo frequent disturbances. In the current socio-economic context characterized by intensive urban development and industrialization, it is of primordial importance for the management of the environment to achieve a better understanding of the functioning and the transfer of contaminants within these ecosystems. The study of the transfer of organic matter and contaminants to the interfaces is thus a crucial issue. The main objectives are to characterize the fish fauna and to determine the food webs; to establish the levels and patterns of spatial variability of contamination by trace elements TEs and persistent organic pollutants POPs; and to identify the sources and the processes having an influence on the levels of contamination throughout the food webs. The characterization of the fish populations and the trophic relations between the compartments of the ecosystem is necessary in order to understand the levels of contamination in TEs and POPs. For the fishes, it is difficult to provide evidence of the phenomenon of bioaccumulation of TEs, except for mercury, but the influence of diet, size and physiological and metabolic requirements is obvious. The great stability, liposolubility and persistence of the POPs confer on them significant bioconcentration and bioamplification capabilities. The concentrations in TEs and POPs recorded, and the detection of banned toxic pesticides, attest to the necessity of paying close attention to this pollution.

Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2015-01-28T16:44:40Z No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_FerramentaAvaliacaoTransporte.pdf: 2706452 bytes, checksum: 81269da8500d7d33620688ec29b7d1a7 (MD5) / Rejected by Edisangela Bastos (edisangela@ufpa.br), reason: on 2015-01-29T18:12:59Z (GMT) / Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2015-01-29T20:48:39Z No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_FerramentaAvaliacaoTransporte.pdf: 2706452 bytes, checksum: 81269da8500d7d33620688ec29b7d1a7 (MD5) / Approved for entry into archive by Albirene Aires (albireneufpa@gmail.com) on 2015-01-30T15:02:12Z (GMT) No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_FerramentaAvaliacaoTransporte.pdf: 2706452 bytes, checksum: 81269da8500d7d33620688ec29b7d1a7 (MD5) / Made available in DSpace on 2015-01-30T15:02:12Z (GMT). No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_FerramentaAvaliacaoTransporte.pdf: 2706452 bytes, checksum: 81269da8500d7d33620688ec29b7d1a7 (MD5) Previous issue date: 2013 / A Amazônia brasileira detém mais de 60% da água doce disponível no Brasil, por onde passa um dos maiores rios do mundo, o Rio Amazonas, tanto em extensão como em volume de água, além de abrigar uma das maiores redes hidroviárias do Planeta, com centenas de rios caudalosos. É nesse sistema que a presente pesquisa se propôs a fazer uma análise quantitativa e qualitativa da frota de embarcações, terminais e demanda de passageiros que são transportados pelos rios da Amazônia brasileira, visando contribuir para o desenvolvimento tecnológico do transporte hidroviário de passageiros na região. Através de um método matemático para o cálculo do valor da tarifa por passageiro, que leva em consideração as características físicas e operacionais de cada linha, buscou-se analisar os valores praticados, assim como otimizou-se os parâmetros de uma embarcação com as condições ideais e de menor custo por passageiro transportado. Neste aspecto verificou-se ainda, que o custo do transporte do passageiro pode ser reduzido com um projeto de embarcação mais adequado para cada linha e respectiva demanda. Os dados, informações e previsões sobre a produção do transporte hidroviário de passageiros são apresentados para melhor entendimento do setor de maneira a possibilitar propostas de transportes mais eficientes, de acordo com as características da via navegável e do ambiente operacional. Com o método de avaliação de custo proposto foi possível verificar que o custo do transporte hidroviário de passageiro na Amazônia não é homogêneo, em virtude da grande diversidade de embarcações que operam em cada linha, e que, a otimização do projeto adequado para cada linha pode ter grande reduções no custo do passageiro transportado. / The Brazilian Amazon holds over 60% of available fresh water in Brazil, through which passes one of the largest rivers in the world the Amazon River, both in extent and volume of water, in addition to housing one of the largest networks waterways of the planet, with hundreds of rivers. It is this system that this research aims to make a quantitative and qualitative analysis of the fleet of vessels, terminals and passenger demand which are transported by the rivers of the Brazilian Amazon, to contribute to the technological development of water transportation of passengers in the region. Through a mathematical model for calculating the value of the fare per passenger, which takes into account the physical and operational characteristics of each line, we have analyzed the values practiced in the lines, as well as optimized the parameters of a vessel with ideal conditions and lower cost per passenger. In this regard it was found that the cost of transportation of the passenger can be reduced with a design most suitable for each vessel line and its demand. The data, information and forecasts on the production of passenger water transport are presented for better understanding of the sector in order to enable more efficient transport proposals, according to the characteristics of the waterway and the operating environment. With the evaluation method proposed cost, we found that the cost of passenger waterway transportation in the Amazon is not homogeneous due to the great diversity of vessels operating in each navigation line, and that the optimization of the design suitable for each line can have major reductions in the cost of passenger transported.

Made available in DSpace on 2014-12-17T14:55:03Z (GMT). No. of bitstreams: 1 FabioAPP.pdf: 1226499 bytes, checksum: 476c4c4dd5d62663a94a43090900b128 (MD5) Previous issue date: 2006-05-19 / The popularization of the Internet has stimulated the appearance of Search Engines that have as their objective aid the users in the Web information research process. However, it s common for users to make queries and receive results which do not satisfy their initial needs. The Information Retrieval in Context (IRiX) technique allows for the information related to a specific theme to be related to the initial user query, enabling, in this way, better results. This study presents a prototype of a search engine based on contexts built from linguistic gatherings and on relationships defined by the user. The context information can be shared with softwares and other tool users with the objective of promoting a socialization of contexts / A populariza??o da Internet estimulou o surgimento das M?quinas de Busca, que t?m como objetivo auxiliar os usu?rios no processo de pesquisa da informa??o na Web. Por?m, ? comum usu?rios formularem consultas e receberem resultados que n?o satisfazem a sua inten??o inicial de pesquisa. A t?cnica Information Retrieval in Context (IRiX) permite que informa??es relacionadas a um determinado tema possam ser atribu?das ? consulta formulada originalmente pelo usu?rio, possibilitando, dessa forma, melhores resultados. Este trabalho apresenta um prot?tipo de M?quina de Busca baseada em contextos constru?dos a partir de um conjunto de sintagmas e de relacionamentos definido pelo usu?rio. As informa??es de contextos podem ser compartilhadas com softwares e com outros usu?rios da ferramenta a fim de promover a socializa??o de contextos.

Made available in DSpace on 2016-08-17T14:53:19Z (GMT). No. of bitstreams: 1 dissertacao Joabe Amaral.pdf: 1492594 bytes, checksum: 667940ee64ccf9cbf29cbf0ed1db27a0 (MD5) Previous issue date: 2012-02-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / In this dissertation, a robust fuzzy PID Takagi-Sugeno control methodology based on gain and phase margins specifications for dynamic systems with time delay in continuous time domain is proposed. A fuzzy model based on the Takagi-Sugeno structure is used to represent the dynamic system to be controlled. Thus, from the input and output data of the dynamic system, the Gustafson-Kessel fuzzy clustering algorithm is used to estimate the parameters of the antecedent proposition (input space) and the rules number of the fuzzy model, while the least mean squares algorithm is used to estimate the parameters of the sub-linear models of the consequent proposition (output space) of the fuzzy model. A mathematical formulation based on PDC (parallel and distributed compensation) strategy is defined from the gain and phase margins specifications for the calculation of PID controllers sub-parameters, in the robust fuzzy PID controller rule base, the linear sub-models parameters of the dynamic system model fuzzy rule base to be controlled. An analysis of necessary and sufficient conditions for robust fuzzy PID controller design, with the proposal of one axiom and two theorems are presented. Computational results to validation of the proposal compared to others control methods widely cited in the literature, with the application in the angular position control of a robotic manipulator, are also presented. / Nesta dissertação é proposta uma metodologia de controle PID nebuloso robusto baseado nas especificações das margens de ganho e fase, para sistemas dinâmicos com atraso, no domínio do tempo contínuo. Um modelo nebuloso com estrutura Takagi-Sugeno é utilizado para representar o sistema dinâmico a ser controlado. Assim, a partir dos dados de entrada e saída do sistema dinâmico, o algoritmo de agrupamento nebuloso Gustafson-Kessel é utilizado para estimar os parâmetros da proposição no antecedente (espaço de entrada) e o número de regras do modelo nebuloso, enquanto que o algoritmo de mínimos quadrados é utilizado para estimar os parâmetros dos sub-modelos lineares da proposição no consequente (espaço de saída) do modelo nebuloso. Uma formulação matemática fundamentada na estratégia de Compensação Paralela e Distribuída (PDC) é definida, a partir das especificações das margens de ganho e fase, para o cálculo dos parâmetros dos sub-controladores PID, na base de regras do controlador PID nebuloso robusto, em função dos parâmetros dos sub-modelos lineares na base de regras do modelo nebuloso do sistema dinâmico a ser controlado. Uma análise das condições necessárias e suficientes de projeto do controlador PID nebuloso robusto, com a proposta de um axioma e dois teoremas, são apresentados. Resultados computacionais para a validação da metodologia proposta comparada a dois métodos de controle nebuloso propostos por Teixeira e Zak (1999) e Wang, Tanaka e Griffin (1996), amplamente utilizados na literatura, com aplicação ao problema de controle de posição angular de um manipulador robótico, também são apresentados.

Since the 18th-century scientists are studying diatoms, fascinated by their beauty and diversity. Their nano- and micropatterned biosilica cell walls are outstanding examples of biologically controlled mineral formation. Although the knowledge about diatom cell wall formation increased over the last 60 years, the process is still far away from being completely understood. Diatom cell walls exhibit highly interesting material properties, making them appealing to material scientists. Due to those properties, diatom cell walls are on the brink of becoming powerful tools in nanotechnology. However, the production of tailored silica structures for nanotechnology requires a much better understanding of the processes and components involved in cell wall morphogenesis. Recent studies set the focus on insoluble organic matrices as important parts of this process, suggesting that they act as templates in silica morphogenesis. Therefore, in this study, the occurrence of insoluble organic matrices and their possible silica precipitation activity was analyzed in the three diatom species T. pseudonana, T. oceanica and C. cryptica. For all three species girdle band and valve derived insoluble organic matrices could be identified. The extracted insoluble organic matrices exhibited structural features present in the corresponding biosilica cell walls. The highest similarities were found in the valve derived matrices of C. cryptica. Accessibility studies showed that the biosilica associated insoluble organic matrices of T. pseudonana were only partially accessible, arguing for an entrapment of insoluble organic matrices in the silica, rather than an attachment to the surface of the cell wall. All examined insoluble organic matrices of the three species exhibited intrinsic silica precipitation activity. The most intriguing structures were formed by the insoluble organic matrices of C. cryptica, yielding a porous silica pattern. The addition of biosilica derived soluble components or long-chain polyamines promoted this process and moreover lead to the reconstitution of biosilica-like hierarchical silica pore patterns. The generated silica structures were templated by the underlying structure of the insoluble organic matrix. The result presented in this thesis make this the first study reporting the in vitro generation of diatom biosilica-like hierarchical silica pore patterns using all natural cell wall components. It supports the hypothesis of microplates acting as templates for biosilica morphogenesis and introduces an interesting experimental setup for silica-based in vitro studies on the mechanism of pore formation in diatoms.

Our planet is traversing the age of human-induced climate change and biodiversity loss. Projected global warming of 1.5 ºC above pre-industrial levels and related greenhouse gas emission pathways will bring about detrimental and irreversible impacts on the interconnected natural and human ecosystem. A global warming of 2 ºC could further exacerbate the risks across the sectors of biodiversity, energy, food, and water. Time- and cost-effective solutions and strategies are required for strengthening humanity’s response to the present environmental and societal challenges. Coastal seascape ecosystems including seagrasses, corals, mangrove forests, tidal flats, and salt marshes have been more recently heralded as nature-based solutions for mitigating and adapting to the climate-related impacts. This is due to their ability to absorb and store large quantities of carbon from the atmosphere. Focusing on seagrass habitats, although occupying only 0.2% of the world’s oceans, they can sequestrate up to 10% of the total oceanic carbon pool, all the while providing important food security, biodiversity, and coastal protection. But seagrass ecosystems, as all of their blue carbon seascape neighbors, are losing 1.5% of their extent per year due to anthropogenic activities. This has adverse implications for global carbon stocks, coastal protection, and marine biodiversity. Seagrass and seascape recession necessitates their science and policy-based management, protection, conservation which will ensure that our planet will remain within its sustainable boundaries in the age of climate change. The present PhD Thesis and research aim is to develop algorithms for seagrass mapping and monitoring leveraging the recent emergences in remote sensing technology―new satellite image archives, machine learning frameworks, and cloud computing―with field data from multiple sources. The main PhD findings are the demonstration of the suitability of Sentinel-2, RapidEye, and PlanetScope satellite imagery for regional to large-scale seagrass mapping; the introduction and incorporation of machine learning frameworks in the context of seagrass remote sensing and data analytics; the development of a semi-analytical model to invert the bottom reflectance of seagrasses; the design and implementation of multi-temporal satellite image approaches in coastal aquatic remote sensing; and the introduction, design and application of a scalable cloud-based tool to scale up seagrass mapping across large spatial and temporal dimensions. The approaches of the present PhD cover the gaps of the existing scientific literature of seagrass mapping in terms of the lack of spatial and temporal scalability and adaptability; the infancy in seagrass and seascape-related artificial intelligence endeavours; the restrictions of local server and mono-temporal approaches; and the absence of new methodological developments and applications using new (mainly open) satellite image archives. I anticipate and envisage that the near-future steps after the completion of my PhD will address the scalability of the designed cloud-native, data-driven mapping tool to standardise, automate, commercialise and democratise mapping and monitoring of seagrass and seascape ecosystems globally. The synergy of the developed momentum around the global seascape with the technological potential of Earth Observation can contribute to humanity’s race to adapt to and mitigate the climate change impacts and avoid cross tipping points in climate patterns, and biodiversity and ecosystem functions.

Morphogenesis of the intricate patterns of diatom silica cell walls is a protein-guided process, yet to date only very few such silica biomineralization proteins have been identified. Therefore, it is currently unknown whether all diatoms share conserved proteins of a basal silica forming machinery, and whether unique proteins are responsible for the morphogenesis of species-specific silica patterns. To answer these questions, we extracted proteins from the silica of three diatom species (Thalassiosira pseudonana, Thalassiosira oceanica, and Cyclotella cryptica) by complete demineralization of the cell walls. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis of the extracts identified 92 proteins that we name ‘soluble silicome proteins’ (SSPs). Surprisingly, no SSPs are common to all three species, and most SSPs showed very low similarity to one another in sequence alignments. In-depth bioinformatics analyses revealed that SSPs could be grouped into distinct classes based on short unconventional sequence motifs whose functions are yet unknown. The results from the in vivo localization of selected SSPs indicates that proteins, which lack sequence homology but share unconventional sequence motifs may exert similar functions in the morphogenesis of the diatom silica cell wall.

Η παρούσα μεταπτυχιακή διατριβή επικεντρώνεται στην μελέτη της παράκτιας ζώνης της νήσου Λέρου στο Νοτιοανατολικό Αιγαίο, παρουσιάζοντας τα αποτελέσματα της ερμηνείας των γεωφυσικών στοιχείων που συλλέχθηκαν από το Εργαστήριο Θαλάσσιας Γεωλογίας και Φυσικής Ωκεανογραφίας (Ε.ΘΑ.ΓΕ.Φ.Ω.) τον Ιούνιο του 2011. Η έρευνα φιλοδοξεί να συνεισφέρει στην ανάδειξη της υποθαλάσσιας πολιτιστικής και φυσικής κληρονομιάς του νησιού, καθώς η συλλογή, επεξεργασία και ερμηνεία του συνόλου των δεδομένων επέτρεψε την αναγνώριση και την λεπτομερή χαρτογράφηση υποθαλάσσιων στόχων μεγάλης ιστορικής και περιβαλλοντικής σημασίας. Ως εκ τούτου, η διατριβή κινείται σε δύο κατευθύνσεις. Η πρώτη κατεύθυνση αφορά στον εντοπισμό στόχων πιθανής ιστορικής σπουδαιότητας που εντοπίστηκαν στην επιφάνεια του πυθμένα ενώ η δεύτερη κατεύθυνση αφορά στον εντοπισμό και την αποτύπωση βιογενών σχηματισμών και συγκεκριμένα λειμώνων P. Oceanica και ασβεστιτικών ροδοφυκών (corallegene formations). Οι θαλάσσιες έρευνες πραγματοποιήθηκαν σε δύο διακριτά στάδια, στην συστηματική αποτύπωση του πυθμένα με ηχοβολιστή πλευρικής σάρωσης (EG&G 272 TD) και την οπτική επιβεβαίωση των αποτελεσμάτων της ηχοβολιστικής αποτύπωσης με σύστημα συρόμενης υποβρύχιας κάμερας. Η ανάλυση και επεξεργασία των ηχογραφιών οδήγησε στον εντοπισμό ναυαγίων που συνδέονται με τη Μάχη της Λέρου (9-10/1943), ένα από τα σημαντικότερα πολεμικά γεγονότα που έλαβαν χώρα κατά τη διάρκεια του Δευτέρου Παγκοσμίου πολέμου, στην ανατολική Μεσόγειο και τα οποία αποτελούν πολύτιμα ιστορικά στοιχεία σε παγκόσμια κλίμακα, μεταξύ των οποίων το βυθισμένο ελληνικό αντιτορπιλικό Βασίλισσα ‘Ολγα (D15). Στο πλαίσιο της δεύτερης κατεύθυνσης εντοπίστηκαν και χαρτογραφήθηκαν οι λειμώνες P. Oceanica και οι σχηματισμοί των ασβεστιτικών ροδοφυκών σχεδόν ανά όρμο περιμετρικά της νήσου. Η σχεδίαση των αντιστοίχων υποθαλάσσιων θεματικών χαρτών της παράκτιας ζώνης της Λέρου αναμένεται να αποτελέσουν ένα σημαντικό εργαλείο στην προστασία και στην ανάδειξη της σημαντικής υποθαλάσσιας ιστορικής και φυσικής κληρονομιάς του νησιού / The present study describes the submarine geophysical survey which was carried out in Leros Island, Aegean Sea and presents the results of the geophysical data analysis. The data were collected by the Laboratory of Marine Geology & Physical Oceanography, department of Geology, University of Patras during the period 11-17 June 2011. The research aims to contribute to the enhancement of underwater cultural and natural heritage of the island, as the collection, processing and interpretation of all of the data has allowed the identification of underwater targets of great historic and environmental importance. Geophysical survey in Leros Island, using a side scan sonar (EG&G 272 TD), coupled with ground-truthing by deploying a Towing Camera System of historic shipwrecks from World War II and of the major seabed habitats, namely Posidonia oceanica and coralligène formations. The survey revealed a great number of shipwrecks associated with the Battle of Leros (9-10/1943), one of the most important military events that took place during the World War II, in the Eastern Mediterranean which are considered as valuable historic data on a global scale, including the sunken Greek destroyer Queen Olga (D15). The design of the thematic maps of the coastal zone of Leros is expected to become an important tool in both protecting and promoting the significant underwater cultural and natural heritage of the island.

Made available in DSpace on 2015-03-04T18:50:51Z (GMT). No. of bitstreams: 1 Tese_Antonio_Boness.pdf: 1734195 bytes, checksum: 60769d0cc4e992347a83d1cf365a0030 (MD5) Previous issue date: 2007-08-02 / Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Apresentamos um modelo matemático geral, baseado na teoria de Cosserat para estruturas flexíveis unidimensionais, em regime de deslocamentos finitos e sujeitas a restrições unilaterais. Ao modelo geral agregamos a hipótese de inextensibilidade e, desprezando os efeitos do cisalhamento e das forças inerciais, formulamos o problema variacionalmente tanto na forma cinemática quanto em Lagrangiano Aumentado. Para esta última formulação, construímos aproximações por elementos finitos de Galerkin e utilizamos um algoritmo do tipo Uzawa para a solução do problema aproximado. Apresentamos estudos numéricos com o intuito de avaliar a formulação, validar o algoritmo de solução e exemplificar possíveis aplicações práticas do modelo. Buscando viabilizar uma análise numérica, realizamos uma linearização consistente do modelo geral apresentado anteriormente, produzindo um modelo em regime de pequenos deslocamentos e deformações, descrito no espaço tridimensional. Para este problema, introduzimos uma aproximação por elementos finitos mistos estabilizados, adicionando à formulação de Galerkin formas residuais de mínimos quadrados provenientes das equações de equilíbrio. Provamos que esta formulação atende às condições suficientes para existência e unicidade de solução, independente da esbeltez da estrutura. Apresentamos estimativas de erro indicando taxas de convergência e resultados numéricos comprovando tais taxas. Apresentamos algumas aplicações dos modelos ao estudo de estabilidade de dutos aquecidos e enterrados, na análise da estabilidade de armaduras de risers e umbilicais e, na área biológica, apontamos as possibilidades de suas utilizações na modelagem de moléculas de ADN.