EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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Item Automatic detection of corrosion in large-scale industrial buildings based on artificial intelligence and unmanned aerial vehicles.(2023) Lemos, Rafael; Cabral, Rafael; Ribeiro, Diogo; Santos, Ricardo; Alves, Vinicius Nicchio; Dias, AndréIn recent years, Artificial Intelligence (AI) provided essential tools to enhance the productivity of activities related to civil engineering, particularly in design, construction, and maintenance. In this framework, the present work proposes a novel AI computer vision methodology for automatically identifying the corrosion phenomenon on roofing systems of large-scale industrial buildings. The proposed method can be incorporated into computational packages for easier integration by the industry to enhance the inspection activities’ performance. For this purpose, a dedicated image database with more than 8k high-resolution aerial images was developed for supervised training. An Unmanned Aerial Vehicle (UAV) was used to acquire remote georeferenced images safely and efficiently. The corrosion anomalies were manually annotated using a segmentation strategy summing up 18,381 instances. These anomalies were identified through instance segmentation using the Mask based Region-Convolution Neural Network (Mask R-CNN) framework adjusted to the created dataset. Some adjustments were performed to enhance the performance of the classification model, particularly defining an adequate input image size, data augmentation strategy, Intersection over a Union (IoU) threshold during training, and type of backbone network. The inferences show promising results, with correct detections even under complex backgrounds, poor illumination conditions, and instances of significantly reduced dimensions. Furthermore, in scenarios without a roofing system, the model proved reliable, not producing any false positive occurrences. The best model achieved metrics’ values equal to 65.1% for the bounding box detection Average Precision (AP) and 59.2% for the mask AP, considering an IoU of 50%. Regarding classification metrics, the precision and recall were equal to 85.8% and 84.0%, respectively. The developed methodology proved to be extremely valuable for guiding infrastructure managers in taking physically informed decisions based on the real assets condition.Item Effect of PWHT on laser-welded duplex stainless steel : the effects of postweld heat treatments on the microstructure, tensile behavior, and corrosion resistance of laser-welded duplex stainless steel were investigated.(2020) Magalhaes, Aparecida Silva; Magalhães, Charles Henrique Xavier Morais; Lima, Milton Sérgio Fernandes de; Alves, Juliane Ribeiro da Cruz; Godefroid, Leonardo Barbosa; Bertazzoli, Rodnei; Faria, Geraldo Lúcio deThe welded joints of duplex stainless steels (DSSs) have been widely used in petrochemical, nuclear, pulp, and paper industries. Welds require a good, superficial finishing and a combination of mechanical and corrosion properties in these types of high-quality, demanding applications. Even though laser welding promotes narrow weld beads and a small heataffected zone, when it is applied to DSSs, it can produce dangerous microstructural discontinuities. In this context, the effects of subsequent heat treatments on the microstructure, corrosion resistance, microhardness, and tensile properties of DSS laser-welded joints are investigated. In this study, samples of UNS S32304 DSS were submitted to two different conditions of laser welding. Subsequently, the plates submitted to the best welding condition were subjected to isothermal heat treatments at different temperatures (850°, 950°, 1050°, and 1150°C) for 10 min. Then they were microstructurally characterized. Phase fraction measurements and microhardness tests were performed. Based on the obtained results, postweld heat-treated samples at 1150°C, which is the best condition, were subjected to corrosion and tensile tests. It was possible to conclude the corrosion properties of the welded joint were significantly improved after the heat treatment. However, the mechanical behavior was strongly influenced by the presence of volumetric discontinuities and intermetallic compounds, which considerably deteriorated the mechanical strength of the material.Item The importance of underpaint corrosion caused by damage to paint on steel structures.(2020) Ribeiro Filho, Guido Lessa; Ribas, Rovadávia Aline de Jesus; Paula, Geraldo Donizetti deThe impact of varying the dry paint film thickness (DFT) on the underpaint corrosion of steel plates obtained from the floor of an offshore oil platform is evaluated. The specimens were all prepared using the same material and paint scheme, and the DFT and exposure conditions in a salt spray chamber were varied and compared with the results obtained in a real situation. The results indicated that corrosion initiated at sites where the paint was damaged, may be more important than corrosion through the undamaged paint due to permeation, even in cases where the DFT is thin. In specimens whose substrates were previously damaged, there were pathological manifestations of osmotic blistering. The underpaint corrosion that occurred after the paint was damaged in the field occurred at an intensity like that observed for the tested specimens.Item The use of rapid prototyping in the joining of fractured historical silver object.(2017) Silva, Maria Luiza Seixas de Souza e; Assis, Paulo Santos; Figueiredo Junior, João Cura D'Ars; Pinto, Maria Aparecida; Paula, Daniella Gualberto CaldeiraPurpose – This paper aims to present a proposal for the restoration of a silver crown by means of fitting pieces produced by the process of 3D modelling and rapid prototyping. It also analyses the benefits of this procedure in restoration of objects weakened by corrosive processes. Design/methodology/approach – Elemental chemical analysis was carried out in the alloy used in the manufacture of the crown and the constructive and corrosive processes present were studied. Three fitting pieces were modelled and prototyped in wax casting by the stereolithography apparatus system aiming to restore the part and protect the original metal against impacts and external tensions which could speed up some deterioration processes. Findings – The procedure presented in this paper has shown that formal and dimensional accuracy, only achieved by means of 3D technologies, made the restoration and mechanical stability of the crown possible without the use of adhesives or welding. Originality/value – The proposed procedure is a new restoration alternative which causes minimal impact to the object and abides by the main standards for modern conservation. It is made with metal which is compatible with the original piece, retractable and easily identifiable.Item Estudo do fenômeno de corrosão na Ponte Marechal Hermes no Rio São Francisco.(2008) Brinck, Fabiana Malta; Cândido, Luiz Cláudio; Neves, Francisco de Assis dasA corrosão é uma das causas mais importantes da deterioração de pontes metálicas. Entre os vários fatores contribuintes para instaurar e acelerar o processo de corrosão em pontes metálicas podem-se citar o envelhecimento das pontes, o aumento da carga de tráfego, ataque ambiental e, algumas vezes, a inadequação de projetos, detalhamento e construção da estrutura. A degradação em geral começa no ponto mais debilitado da estrutura, sendo, portanto, necessário procurar por evidências visuais de sua ocorrência. A ocorrência e extensão dos danos e defeitos encontrados em inspeções sucessivas são usadas para estimar a deterioração de componentes estruturais. Os resultados dessas inspeções servem, portanto, como critério na tomada de decisão para a aplicação de medidas de manutenção e reabilitação. O objetivo deste trabalho é investigar e diagnosticar o fenômeno de corrosão desenvolvido na Ponte Marechal Hermes (PMH), sobre o Rio São Francisco, que se encontra num estado avançado de degradação, além de descrever a metodologia adotada de inspeção.