PPGEM https://repositorio.ufpb.br/jspui/handle/tede/4458 2026-09-01T12:46:29Z 2026-09-01T12:46:29Z Almeida, Ana Natália Fragoso de https://repositorio.ufpb.br/jspui/handle/123456789/38824 2026-09-01T10:44:13Z 2026-03-16T00:00:00Z

Título: Desenvolvimento de metodologia de caracterização e quantificação de materiais policristalinos Autor(es): Almeida, Ana Natália Fragoso de Orientador: Torres, Sandro Marden Abstract: The need for legal expertise in public works has intensified in recent years, making it essential to verify the composition and compliance of the materials used in relation to the technical standards established in tender notices. Among the main materials used in civil construction are clinker, cement, mortar, and concrete, whose proper characterisation is essential to ensure the structural integrity, durability, and performance of buildings. Considering the variability in structural performance according to the proportions of materials used, this study proposes a methodology focused on the technical assessment of materials used in civil engineering, with an emphasis on identifying conformities with the standards established in tender notices, which may compromise safety or constitute irregularities in public works. However, there is a need to develop accessible methodologies that allow for consolidated quantitative assessments of polyphasic material compositions using advanced microstructural characterisation techniques, and which can be used in the conduct of forensic examinations. This methodological integration provides greater accuracy in verifying composition and diagnosing non-conformities, technically supporting the work of Legal Engineering. The approach employed uses a combination of advanced characterisation techniques, such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) applied to the quantification of the crystalline phases of clinker and Portland cement, mortars and concretes. The results obtained demonstrate the applicability of the proposed methodology as a robust and reliable tool for quality control and expert verification of materials used in civil construction. Editor: Universidade Federal da Paraíba Tipo: Tese

2026-03-16T00:00:00Z Silva, Aline Karla Barbosa da https://repositorio.ufpb.br/jspui/handle/123456789/38822 2026-09-01T10:24:47Z 2025-12-15T00:00:00Z

Título: Desenvolvimento de ligas quasicristalinas (AlCuFeCo) a partir de elementos precursores reciclados para uso potencial aplicações em engenharia Autor(es): Silva, Aline Karla Barbosa da Orientador: Lima, Danielle Guedes de Abstract: The development of high-performance quasicrystalline alloys is traditionally associated with the use of high-purity raw materials, leading to increased costs and environmental impact. In this context, this thesis aimed to develop Al–Cu–Fe quasicrystalline alloys doped with Co using recycled precursors, and to evaluate their microstructural, mechanical, surface, and electrochemical performance in comparison with alloys produced from pure elements. Al₆₅Cu₂₂Fe₉Co₄ alloys were fabricated by conventional casting and subjected to heat treatments Characterization was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Vickers microhardness, wettability measurements (contact angle in distilled and saline water), and corrosion tests.XRD results confirmed the formation and stability of icosahedral (ψ) and decagonal (D) quasicrystalline phases under all investigated conditions, coexisting with β and β₂ and λ approximant phases. Heat treatment promoted the stabilization of the icosahedral phase in alloys produced from pure elements, while the decagonal phase remained more persistent in recycled alloys. EDS analyses indicated that microstructural evolution occurs through internal chemical redistribution, maintaining compositions within the quasicrystalline stability domain despite the presence of residual impurities. Microhardness measurements showed high and stable hardness values, with only minor variations. Wettability tests revealed consistently high contact angles, indicating low surface wettability typical of quasicrystalline materials..Overall, the results demonstrate that recycled precursors can be successfully employed to produce Al–Cu–Fe–Co quasicrystalline alloys with properties comparable to those obtained from high-purity raw materials, validating a sustainable and efficient processing route. Editor: Universidade Federal da Paraíba Tipo: Tese

2025-12-15T00:00:00Z Medeiros, Viviano de Sousa https://repositorio.ufpb.br/jspui/handle/123456789/38816 2026-09-01T06:11:07Z 2024-07-30T00:00:00Z

Título: Estudo de caso para predição de falhas em redes de abastecimento de água utilizando Redes Neurais Autor(es): Medeiros, Viviano de Sousa Orientador: Santos, Moisés Dantas dos Abstract: The water supply is considered an important service for cities because provides an essential asset for the lives of its inhabitants, as for the proper functioning of industries, institutions, and harming the social well-being of people. Faults in water supply systems can considerably affect people’s lives with losses and damages, in addition to causing damage to the economy of entire regions. Proposing solutions that optimize the water supply process, reducing losses and improving the quality of the service offered can aggregate value to people, companies, governments and cities. This work aims to investigate and propose solutions for the prevention of failures in water distribution networks based on Predictive Analysis and Machine Learning techniques, using real data from a water supply and sewage concessionaire. Editor: Universidade Federal da Paraíba Tipo: Tese

2024-07-30T00:00:00Z Valença, Antonio Karlos Araújo https://repositorio.ufpb.br/jspui/handle/123456789/38734 2026-08-21T06:12:38Z 2026-03-30T00:00:00Z

Título: Desenvolvimento e validação de protótipo experimental para estudo do envelhecimento fototérmico de superfícies seletivas solares Autor(es): Valença, Antonio Karlos Araújo Orientador: Gomes, Kelly Cristiane Abstract: The increasing demand for renewable energy sources has driven the use of solar thermal collectors, whose performance depends on the efficiency and durability of selective surfaces. However, these coatings undergo degradation under harsh operating conditions, requiring accessible photothermal evaluation methods. Given this context, this work presents the development and validation of an experimental prototype for the photothermal aging analysis of solar selective surfaces. The prototype utilizes halogen dichroic lamps as radiation sources, with temperature data acquisition performed via an Arduino microcontroller and thermocouple sensors. The methodology consisted of subjecting selective films to different ultraviolet radiation conditions (UV-C and UV-A) and thermal stress within the developed device. Chromium-based surfaces were investigated in three configurations: Cr (S1), Cr+Cr/Cr2O3 (S2) and Cr/Cr2O3 (S3), deposited by Magnetron Sputtering. The samples were characterized using UV-Vis-NIR, XRD, and Optical Profilometry. Results indicated losses in the absorptivity of the exposed substrates, with a mean reduction of 1.28%. Among the fabricated films, the S1 configuration demonstrated the highest stability (a variation of only -0.09%), while S2 showed the lowest resistance (-15.89% loss). XRD analysis revealed that the film structure maintained an amorphous character across all configurations and exposure environments, indicating phase stability. However, profilometry pointed out that the exposure of the S2 film to the prototype caused a greater roughness reduction effect compared to other environments. The prototype operated stably at 80 °C, validating its effectiveness as an innovative and low-cost tool for studying the durability of absorber coatings. Editor: Universidade Federal da Paraíba Tipo: Tese

2026-03-30T00:00:00Z