TEDE Coleção:http://www.bdtd.uerj.br/handle/1/36812024-03-28T14:49:39Z2024-03-28T14:49:39ZEstudo do comportamento estrutural estático e dinâmico de tanques de aço para armazenamento de líquidosLopes, Matheus Abreuhttp://www.bdtd.uerj.br/handle/1/215232024-03-05T14:29:29Z2023-12-15T00:00:00ZTítulo: Estudo do comportamento estrutural estático e dinâmico de tanques de aço para armazenamento de líquidos
Autor: Lopes, Matheus Abreu
Primeiro orientador: Silva, José Guilherme Santos da
Abstract: The scenario of increasing oil production in the Brazilian oil and gas industry has been demanding more efficiency in the operation and maintenance of logistic assets, such as cylindrical steel tanks used for the storage of oil and its derivatives. On the other hand, these equipment experience damage throughout their lifespan, such as structural deformations due to their high slenderness ratio, because of their very low thickness-to-diameter ratios. In this context, it is necessary to assess the integrity of these equipment in the presence of these structural damages to ensure a safe operational continuity. The consideration of imperfections in the calculation models must be as realistic as possible to obtain a precise assessment of the structure in the presence of defects. However, methods for the dimensional inspection of large structures like storage tanks often involve topographical surveys at specific points on the structure, which may not be very suitable for accurately quantifying imperfections. Therefore, the use of 3D laser scanning inspection tools can be an excellent ally. Regarding failure modes, tanks are susceptible to wind-induced buckling, especially in the presence of structural imperfections. Wind, which is a phenomenon with unstable and random behavior, is typically considered as a static load with a deterministic formulation. However, this consideration may not reveal certain behaviors, such as the dynamic buckling of tanks. Therefore, considering the dynamic and non-deterministic effects of wind is recommended to capture these events. In addition, other failure modes such as plastic collapse and excessive localized plastic strains can compromise structural integrity and should be investigated through calculation models that allow for the assessment of the structure in its current state, with a precise representation of its geometry. Thus, this work aims to develop a methodology for the structural analysis of operating storage tanks containing imperfections (deformations) in their structure. The methodology involves the precise dimensional survey of the structure using 3D laser scanning, with the results used to calibrate a finite element model. The developed model is employed in static analyses focused on evaluating failure due to plastic collapse and excessive localized plastic deformations, with considerations and proposals related to internationally recognized normative criteria. Dynamic analyses, considering complete nonlinearity, are conducted to assess susceptibility to dynamic buckling induced by wind when non-deterministic behavior is considered. Among the various conclusions of this work, it is highlighted that the non-deterministic dynamic behavior of wind can lead deformed tanks to dynamic structural instability, and structural reinforcement elements can be of great help in restoring buckling resistance, increasing the latter by an average of up to 711%.
Instituição: Universidade do Estado do Rio de Janeiro
Tipo do documento: Tese2023-12-15T00:00:00ZTransferência de calor em aletas porosas por métodos analíticos e numéricos em problemas não linearesQuirino, Jonatas Mottahttp://www.bdtd.uerj.br/handle/1/185242024-02-27T18:31:06Z2022-09-13T00:00:00ZTítulo: Transferência de calor em aletas porosas por métodos analíticos e numéricos em problemas não lineares
Autor: Quirino, Jonatas Motta
Primeiro orientador: Correa, Eduardo Dias
Abstract: The analysis of heat dissipation problems involving fins a re t ypically expressed in situations of thermal dissipation, which is increased by the extended surface. Many problem models of this type have already been developed, where each model starts from presuppositions, simplifications or approximations that allow or c ollaborate with the solution of the problem. In this sense, this work seeks a new approach to the problem, proposing an analytical and a numerical perspective in a modeling that includes factors and phenomena disregarded by the specific l iterature for an application where there is heat dissipation from a primary surface, in which it is connected a porous fin. The fin porosity makes the situation more sophisticated, and this analysis in many studies is not performed properly, as the internal pores of the fin allow the heat exchange surface to be maximized. Allied to this, a non-linear model will be implemented, as the heat Exchange by thermal radiation, as well as thermal convection will be evaluated, which makes the equation that governs the problem a non-linear model. For modeling, the equation is based on Darcy’s method for porous media, in which numerical simulations seek the solution of a sequence of linear problems, where each element of this sequence has an equivalente minimum principle, which has as its limit the solution of the original problem. The Finite Differences method is applied to the nonlinear equation that governs the problem and, thus, the proposed sequence of linear problems and their convergence are studied. Finally, the influence of the physical parameters of radiation and how it brings the model closer to real situations is investigated.
Instituição: Universidade do Estado do Rio de Janeiro
Tipo do documento: Tese2022-09-13T00:00:00ZDeterminação das propriedades do revestimento metálico obtido por aspersão térmica e análise de sua influência na eficiência da transferência de calor em tubos de caldeiras de usinas termelétricasCampos, Pamella Kesseler dehttp://www.bdtd.uerj.br/handle/1/183182024-02-27T18:31:06Z2022-03-25T00:00:00ZTítulo: Determinação das propriedades do revestimento metálico obtido por aspersão térmica e análise de sua influência na eficiência da transferência de calor em tubos de caldeiras de usinas termelétricas
Autor: Campos, Pamella Kesseler de
Primeiro orientador: Diniz, Marília Garcia
Abstract: Mineral coal is a fuel that can be used by thermoelectric plants to generate electricity, however, the solid residues of its combustion, so-called ash, cause erosion and corrosion in the internal components of boilers that operate at high temperatures, causing failures in the system. This study proposes a metallic coating based on Fe-Cr-Si, obtained using the electric arc thermal spray technique as an alternative for protecting the most affected parts of boiler tubes by the ash impact. Optical microscopy (OM), scanning electron microscopy (SEM), semi-quantitative chemical analysis by Energy Dispersive Spectroscopy (EDS), X-ray diffraction (XRD), roughness measurements, pull-off adhesion tests were used. Thermal diffusivity measurements and mathematical modelling were elaborated to evaluate the thermal exchange efficiency impact of the coating in thermoelectric plant boiler tubes. The results showed that the chemical components of the sprayed wire were well incorporated into a coating with a hardness of 730.54 ± 164.28 HV, approximately three times greater than the hardness of boiler pipes and only 11% less than the hardness of ash. XRD identified the presence of crystalline phases in the coating and adhesion tests showed that the failures were cohesive without substrate exposure. The presence of the coating reduced heat exchange of approximately 0.64% / tube length. These results showed that the proposed coating, which has a lower cost compared to others, be a promising solution to avoid unscheduled shutdowns in thermoelectric boilers.
Instituição: Universidade do Estado do Rio de Janeiro
Tipo do documento: Tese2022-03-25T00:00:00ZStochastic mathematical-computational simulations to unravel mechanical relations of fluid flow and influence of actin regulators on filopodial dynamicsLeal, Thiago Francohttp://www.bdtd.uerj.br/handle/1/177982024-02-27T18:31:06Z2020-12-28T00:00:00ZTítulo: Stochastic mathematical-computational simulations to unravel mechanical relations of fluid flow and influence of actin regulators on filopodial dynamics
Autor: Leal, Thiago Franco
Primeiro orientador: Moura, Carlos Antônio de
Abstract: A actina é a proteína mais abundante nas células eucarióticas, onde formam polímeros filamentosos (actina-F) e se organizam em redes que fornecem o esqueleto das células e desempenham papéis vitais em muitas funções celulares. Por exemplo, feixes paralelos proeminentes de actina-F mediam a formação e a dinâmica dos filopódios, que são longas protrusões de membrana, semelhantes a dedos, em células ou neurônios em crescimento. Os filopódios têm funções importantes na migração e comunicação celular, relevantes para o desenvolvimento neural, envelhecimento, degeneração e regeneração. No filopódio, a actina-F exibe um padrão de “esteira” constante, isto é, refluxo de todo o feixe de actina-F impulsionado por sua polimerização na ponta distal do filopódio e sua desmontagem concomitante na base do filopódio. Sabe-se que várias proteínas reguladoras da actina mediam e regulam esses processos. Além disso, grandes quantidades de actinas monoméricas são necessárias como blocos de construção na ponta dos filopódios e precisam percorrer todo o estreito espaço interno ao longo do comprimento dos filopódios. Para entender as bases mecânicas da esteira de actinas no filopódio, este trabalho apresenta uma formulação alternativa de modelo estocástico que simula os deslocamentos de moléculas. Ele considera não apenas difusão como fenômeno de transporte essencial, mas inclui fluxo citoplasmático na direção do topo (a fim de repor o volume removido pelo fluxo retrógrado dos filamentos de actina), mas também as propriedades e afinidades específicas dos reguladores de actina, em particular profilina e Ena/VASP. Uma implementação que integra parâmetros físicos e bioquímicos em um modelo computacional foi possível por meio de simulações centradas em partículas, uma abordagem que se mostra sem precedente em modelagem na biologia. Quando aplicado, o modelo centrado em partículas desenvolvido gerou filopódios de até 40 µm de comprimento, a dinâmica do fluxo interno no filopódio pôde ser deduzida e nos permitiu testar como os diferentes parâmetros contribuem para esta dinâmica. Além disso, tem a capacidade de ser refinado ao adicionar gradualmente mais ou melhores parâmetros obtidos por estudos biológicos ou físicos, servindo assim como um meio interativo de previsão e validação. O modelo centrado nas partículas desenvolvido aqui demonstra claramente o potencial desta estratégia para uma ampla aplicação em problemas biológicos.
Instituição: Universidade do Estado do Rio de Janeiro
Tipo do documento: Tese2020-12-28T00:00:00Z