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Monitoramento da integridade estrutural a partir de sensoreamento de baixo-custo: Investigação de técnicas de inteligência artificial para classificação de danos estruturais
(Universidade Federal de São Carlos, 2023-11-16) Hagihara, Rodrigo Jun; Shiki, Sidney Bruce; https://lattes.cnpq.br/0573973677787523; https://lattes.cnpq.br/7402833011834318
In engineering, a structure is designed considering its possible failure due to damage that occurs over time. In this context, in order to extend the useful life of components, avoid failures and operational problems, periodic maintenance is carried out. Several studies are conducted on maintenance based on real-time monitoring of the state of a structure, anticipating the detection of damage. The high precision and constant dependence on human resources to obtain conclusive parameters makes the process costly. Therefore, the biggest obstacle for monitoring is differentiating between damaged and undamaged structures using low-cost equipment and statistical pattern recognition algorithms. In the present work, supervised learning techniques were used to analyze simulated vibration signals and vibration signals of a structure for correlation with different types of damage. Using MATLAB, ADXL335 accelerometer and ESP-32 microcontroller to monitor the state of a simple two-story structure excited by external impact-type forces, it was possible to extract the natural frequencies and damping coefficients as main attributes for classifying the dimension of the associated damage. . At the end of the study, it was found that the different classifiers Medium Gaussian SVM, Medium KNN, Medium Tree and Linear Discriminant achieved accuracy greater than 85% to highlight the differences between damage conditions. Different performance metrics were analyzed to prove their accuracy, such as: true positive rate, true negative rate, positive predictive values, false discovery rate, false positive rate, ROC curve and AUC. By comparing the results obtained with the structure and simulated signals, the effectiveness of artificial intelligence and the feasibility of using economically accessible instrumentation to monitor structural integrity in small structures were evaluated. Despite the need for a large amount of data to obtain good results, it is believed that the model obtained can contribute to the generation of new algorithms capable of classifying different types of damage to structures.
Estudo do comportamento de alvenaria estrutural com juntas finas de composto polimérico
(Universidade Federal de São Carlos, 2023-11-16) Sipp, Gustavo; Margarido, Ana Paula; https://lattes.cnpq.br/2507101291061830; Parsekian, Guilherme Aris; https://lattes.cnpq.br/7798651726059215; https://lattes.cnpq.br/3638400400620590
This research aimed to evaluate the behavior of concrete block structural masonry built with thin polymer composite mortar. The construction of structural masonry with thin joints has been used for some years in Europe, and some countries already have design standards considering its application. However, there are still no standards for the design of structural masonry with thin joints made of polymeric compounds, due to the lack of knowledge about the behavior of masonry laid with this type of material. This research was developed to evaluate the behavior of masonry in compression through tests carried out on prisms, small walls and walls. A step was also developed to evaluate the influence of filling the vertical joint on the shear behavior of the masonry. The flexural behavior of the masonry was also evaluated through bending resistance tests carried out on prisms according to the procedure described in ABNT NBR 16868-3 (2020) and also using the lever method provided for in the Australian standard AS 3700 (2017). Three types of concrete blocks with a nominal size of 140x190X290 mm were used, with different values of compressive strength and also two polymeric compounds from different producers. Procedures were proposed for performing tests to characterize the mechanical properties of polymeric compounds. When performing compressive strength tests, it was possible to notice differences between the compounds from the two producers. This difference would not be perceived just by carrying out the characterization tests specified in NBR 16590-2 (ABNT, 2017); therefore, they can be used to differentiate the properties of different polymeric compounds with greater precision. The use of plastic wedges can assist in the laying process, to ensure the alignment of the rows. NBR 16590-1 (ABNT, 2017), points out filling the vertical joint as optional, however, shear resistance tests indicate that there is a decrease of around 60% in shear resistance for samples built without filling the joint vertically, indicating the need to fill it out. The tests show that the equations and expressions used for conventional masonry cannot describe the behavior of thin-joint masonry laid with polymeric compounds. For conventional masonry there is a considerable increase in the modulus of elasticity of the masonry as the compressive strength of the block used increases, however, in the case of thin joint masonry this behavior was not observed, and the modulus did not vary much with the use of blocks of different resistance levels. An equation was proposed to predict the modulus of the masonry based on the characteristics of the blocks and polymeric compounds, enabling greater precision in estimating the modulus of this type of masonry. Performance tests were carried out on wall specimens without the presence of rendering mortar or any other surface coating. The results showed satisfactory behavior for the suspended load and hard body impact tests. For the thermal shock test, moisture was observed passing to the opposite side of the wall during water spraying, indicating the need to apply a coating so that this type of masonry is capable of guaranteeing watertightness.
Uma leitura política dos contos Rip Van Winkle (1819) e A lenda do cavaleiro sem cabeça (1820), de Washington Irving (1783-1859)
(Universidade Federal de São Carlos, 2023-11-16) Prearo, Paula Aline; Ferreira, Carla Alexandra; https://lattes.cnpq.br/5522506928191940; https://lattes.cnpq.br/5277481874887785
The objective of this master's thesis is to investigate the short stories Rip Van Winkle and The legend of Sleepy Hollow - The legend of the headless horseman -, by Washington Irving, from the perspective of dialectics, in other words, of sociological criticism, as postulated by the American theorist Fredric Jameson in The political unconscious (1992) and two other great exponents, who contribute to the delineation of the theoretical contribution of the analysis: the Brazilian literary critic Antonio Candido and Roberto Schwarz, active critic in the literary sphere. In this way, we seek to investigate, in a dialogue between literature and society, or between form and content, how the two tales mobilize, in their intrinsic organization of form, the idealization of the dream of American nation-building and its identity clashes in the face of various regional, cultural, economic, and political divisions that made up a precursor and original identity of the United States, beyond the children's reading attributed to the tales nowadays. The analysis is guided by the three interpretative levels proposed by Fredric Jameson, in which the first deals with the manifest content of the work - the text itself - and its proximity to the universe of literature for children, the second deals with the social problems that interpellate the tales, and the third expands semantically, through the ideology of the form, the interpretation of the tales as inherent parts of the construction of the history of the country, of the formation of the American nation, besides clarifying, through the form itself, the reasons why the tales are attributed the classification of children's literature.