https://repositorio.ufpb.br/jspui/handle/tede/5433 PPGECAM 2026-05-30T07:56:52Z https://repositorio.ufpb.br/jspui/handle/123456789/38099 Título: Estudo analítico-numérico de placas submetidas a ações pontuais e distribuídas em linha Autor(es): Siqueira, Ana Clara Ferreira Orientador: Mendonça, Ângelo Vieira Abstract: This work aims to discuss aspects of obtaining analytical and numerical solutions for plate problems, with or without elastic foundation support, subjected to point loads and/or line-distributed loads, using Kirchhoff and Mindlin plate theories. The analytical solutions for these problems were derived by manipulating the Dirac delta function (δ) for concentrated loads and the Heaviside function (H) for line distributions. Additionally, the strategies for obtaining the analytical solutions were based on the Levy and Navier methods. To enable numerical solutions for the plate problems, stiffness matrices associated with Winkler and Pasternak foundations were derived through mathematical manipulations compatible with the finite element formulations of DKT (Discrete Kirchhoff Triangle) and DST (Discrete Shear Triangle) elements, combined with linear or pseudo-consistent interpolations of transverse displacements within the element domain. Several analyzes were carried out involving different properties, boundary conditions and loading, the results of which were validated with analytical and/or numerical responses Editor: Universidade Federal da Paraíba Tipo: Dissertação 2025-07-31T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38097 Título: Análise dinâmica de placas duplas e delgadas pelo método dos elementos de contorno Autor(es): Rodrigues, Moab Bezerra Orientador: Mendonça, Ângelo Vieira Abstract: Plates are structural elements widely used in engineering applications, appearing in fields such as Civil Engineering, Mechanical Engineering, and Aerospace Engineering. Double- plate systems, in particular, are found in sandwich structures, nanometric structures, and highway and railway pavements, the latter two often being subjected to dynamic loading conditions. Accurate analysis of these systems is essential, especially when their interaction with elastic foundations is considered. Although analytical solutions are important, they are frequently restricted to simple geometries and boundary conditions, which limits their applicability. In this context, the primary objective of this work is to develop numerical solutions, using the Boundary Element Method (BEM), for thin double-plate systems connected by a Winkler elastic foundation under steady-state dynamic conditions. In addition, secondary discussions are extended to isolated single plates or single plates supported by a Winkler elastic foundation. The construction and validation of the numerical solutions presented in this study follow these steps: initially, the differential equations of motion defined in the continuous medium (plate) are transformed into equivalent integral equations valid over the domain and/or boundary of the plate through the application of the weighted residual method (where the equations of motion are weighted by fundamental solutions). A key contribution of this work is the original derivation of the fundamental solutions for the dynamic problem of double plates, which were previously unavailable in the literature. The discrete solution of the dynamic plate problem is obtained by discretizing the boundary into linear isoparametric boundary elements. After evaluating the corresponding integrals, an algebraic system is assembled. Finally, once the boundary conditions are imposed, the dynamic responses can be determined. Several examples using the BEM solution are presented and validated against analytical and/or numerical solutions, yielding relative errors lower than 1% for a discretization with 32 straight elements in rectangular plates and 8 curved (arc) elements in circular plates, implying on consistence of BEM solution showed. Editor: Universidade Federal da Paraíba Tipo: Dissertação 2026-03-27T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38094 Título: Drenagem urbana e soluções baseadas na natureza : estratégias para o controle de alagamentos em João Pessoa, Paraíba Autor(es): Souza, Sara Angélica Santos de Orientador: Silveira, José Augusto Ribeiro da Abstract: The intensification of urbanization and the increase in soil impermeabilization have amplified the occurrence of urban flooding. This research analyzed how urban drainage is addressed in the normative instruments of the municipality of João Pessoa, Paraíba, evaluating the potential for incorporating sustainable measures based on Nature-based Solutions (NbS) as a complementary strategy to mitigate the hydrological impacts associated with flooding events. The study combined documentary analysis of municipal legislation, interviews with two public managers, and hydrological modeling using the Storm Water Management Model. The empirical application was conducted in the Torre neighborhood, where critical rainfall scenarios were simulated with the implementation of permeable pavements and rain gardens in 50% of the analyzed impermeable area. The results indicate that, although there are instruments related to sanitation and climate adaptation, sustainable drainage is not yet fully institutionalized in the municipality. The interviews revealed technical recognition of the importance of NbS, but also pointed to normative, financial, and institutional barriers. The modeling indicated a significant reduction in the maximum water depth and accumulated volume. Regarding the maximum accumulated volume, Section 2 presented the most expressive result, with a reduction of 82.7%, suggesting greater sensitivity to the implemented interventions. This behavior indicates that the adopted measures acted efficiently in retaining and infiltrating water at the source, delaying surface runoff. Concerning maximum water depths, Section 1 showed the greatest reduction compared to the other sections, reaching 33%, which may be associated with hydraulic limitations of the inlet structures present at the site. Regarding the emptying time, Section 2 also showed the greatest reduction (17%). The more modest results suggest that the final runoff remains conditioned by the structural capacity of the existing drainage network. In other words, drainage efficiency continues to be limited by the installed infrastructure. It is concluded that the implementation of NbS is feasible and necessary; however, it depends on legislative advances, intersectoral integration, and the strengthening of specific public policies for sustainable urban drainage. Editor: Universidade Federal da Paraíba Tipo: Dissertação 2026-03-10T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38084 Título: Estudo teórico e experimental da produção de biogás e do substrato bovino e humano em biodigestor: caracterização do escoamento em modelagem cilíndrica Autor(es): Carvalho, Igor Antonio de Oliveira Orientador: Santos, Carlos Antônio Cabral dos Abstract: This thesis investigates experimentally and theoretically the production of biogas from bovine and human substrates in biodigesters, as well as the modeling of the flow of these substrates. The dual methodology combined the construction and operation of batch and continuous prototypes with the rheological characterization of the substrates, the quantification of biogas, and the analysis of its composition by gas chromatography. In parallel, a mathematical model based on conservation equations was developed and solved using the Generalized Integral Transform Technique to characterize the velocity, temperature, and concentration profiles. The results revealed the clear superiority of the human substrate, which generated 636.2 liters of biogas with 63.9% methane from 5 kg, surpassing the 506.9 liters and 51.5% methane of the bovine substrate. Standardizing the total solids content at 10.85% allowed for a fair comparison and the generation of a comprehensive set of dimensionless numbers from experimental data, including Reynolds, Prandtl, Schmidt, Sherwood, Biot, and Péclet. These parameters serve as a tool for analyzing real systems. Modeling via GITT, validated with the literature, predicts radial temperature and concentration gradients, revealing low-conversion zones that limit overall efficiency. Crucially, the distributed study for sizing and maximum rate operation defined that a continuous feed, after the substrate transformation period, allows for maximum operation of the biodigester, with the minimum reactor capacity. It is concluded that human substrate is more efficient for biogas production. The GITT methodology proved to be accurate in characterizing the transport specifications in the reactor. As its main contribution, the thesis provides an integrated methodological framework and a set of critical operational and dimensional parameters that enable the design, performance prediction, and improvement of biodigestion systems, with direct impacts on renewable energy generation and sustainability. Editor: Universidade Federal da Paraíba Tipo: Tese 2025-10-28T00:00:00Z