https://repositorio.unifei.edu.br/jspui/handle/123456789/55 2026-06-03T22:51:49Z https://repositorio.unifei.edu.br/jspui/handle/123456789/3173 Título: Aquisição e validação de sinal de ruído eletroquímico Abstract: Corrosion is a global problem, which implies costs in industrialized countries of up to 4.5% of GDP, with either economic, but also social and environmental impacts. In the case of Brazil, the waste of water supply networks due to leaks loss is quite significant and much of it is caused by network degradation, indicating that corrosion control should be promoted whenever possible. This study proposes a corrosion monitoring system, in system subject to the use of inhibitor, with the approach of passive technique for monitoring corrosion by electrochemical noise (EN), in which the classification of events in a corrosion sensor by EN is part of methodological study for structural integrity (or “health”) monitoring system (SHM). Due to very dynamic and stochastic nature of the signal, this study and analysis of EN measurements (ENM) considers numerical and graphic characteristics of two corrosion systems both in saline aqueous solution: carbon steel and stainless steel. These experiments are repeated for accumulating data, which allow the generation of several graphs in time and frequency domains, from which at least one characteristic is extracted, which has a good correlation with data from corrosion processes. Then, based on a supervised machine learning system, the training data allows the model to be calibrated. From the test data, the correctness rate of the model above 50% is verified. Tipo: Dissertação 2022-02-17T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4427 Título: Detecção automática de AVNRT em pacientes pediátricos utilizando aprendizado de máquina e sinais de ECQ Abstract: This work proposes a computationally efficient and reproducible approach for the automatic detection of beats indicative of AVNRT in electrocardiograms of pediatric patients. The automatic identification of AVNRT in pediatric patients is a subject practically unexplored in the literature, but it has many benefits, including faster triage, support for emergency clinical decisions, and enabling continuous monitoring solutions in wearable devices. For the proposed technique, beats were segmented based on the detection of R peaks, and temporal and morphological characteristics were extracted from each beat, including classic descriptors (amplitudes and RR intervals) and Hjorth parameters (Activity, Mobility, and Complexity), which synthesize information on amplitude, approximate frequency, and temporal variation with low computational cost. The evaluation was conducted using the public database Leipzig Heart Center ECG Database, containing records of 13 pediatric patients diagnosed with AVNRT. Three supervised machine learning models were trained and compared: Support Vector Machine (SVM), Random Forest, and LightGBM. The metrics obtained in the tests indicated performance comparable to or superior to the state of the art in terms of discrimination and balance between precision and sensitivity, with an F1-score of 0.983 and an AUC of 0.989 in SVM; LightGBM presented a comparable F1-score (0.986) with lower prediction latency, suggesting an operational advantage for real-time applications. Compared to previous studies, the results obtained were similar to or superior to those reported in analogous tasks in predominantly adult populations, indicating the potential of the proposed low-complexity methodology as an efficient alternative to deep models, especially in data-scarce scenarios. Tipo: Dissertação 2026-03-13T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4426 Título: Análise dos requisitos de flexibilidade para atendimento à rampa da geração intermitente e o papel dos leilões de reserva de capacidade Abstract: The increasing participation of solar photovoltaic and wind generation in the global and national energy matrix has presented significant challenges for the operation and planning of electrical systems. The intermittent and variable nature of these energy sources necessitates greater flexibility within electrical systems to ensure the stability and reliability of energy supply. In this context, analyzing the flexibility requirements to accommodate the output ramps of intermittent generation becomes essential. Furthermore, capacity reserve auctions emerge as a crucial mechanism to ensure the availability of flexible resources that can respond swiftly to fluctuations in generation. These auctions play a fundamental role in maintaining the balance between supply and demand, thereby promoting energy security and economic efficiency. Consequently, this dissertation aims to deepen the understanding of the strategies and mechanisms that can be implemented to address the challenges posed by the integration of solar photovoltaic and wind energy. The research will contribute to the development of policies and practices that foster the sustainability and resilience of electrical systems, aligning with the objectives of energy transition and climate change mitigation, demonstrating in its results the dichotomy of risk experienced today in the operation of the National Interconnected System, and the growing need for capacity and flexibility attributes, contracted through capacity reserve auctions. Tipo: Dissertação 2026-02-11T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4425 Título: “Revelemo-nos mais por atos do que por palavras”: no rastro dos atos de uma universidade contra o racismo Abstract: The theme of this interdisciplinary research focuses on the quota policy applied to public higher education as a possibility for reflection on hegemonic development and other paths to development. Therefore, it is delimited that this policy can be understood from a sociotechnical perspective based on studies in STS. The chosen framework consists of a sociotechnical analysis of Law 12.711/2012, the Quota Law, within the scope of a federal university in southern Minas Gerais. The rationale for this research is that the recent reformulation of the Quota Law is considered an opportune moment to explore an unusual approach to the law, situating it as a sociotechnical process (technology). This premise opens space for a reflection that goes beyond measuring efficiency, as it also investigates the sociotechnical meanings underlying the artifact. In this effort, the following question is formulated: since the implementation of the Quota Law at the Federal University of Itajubá, what have been its actions and reactions regarding the racial issue? The overall objective is to analyze the implementation of the quota law in an academic environment that maintains a dominant conception of Science and Technology. The main results indicate the evident effectiveness of quotas, although there is still a glaring disparity in internal racial demographics, especially regarding the presence of Black women. Furthermore, what remains unsaid reveals that the university has historically avoided an effectively anti-racist stance. It is guided by a cognitive model that understands development in its conventional aspect, which is incompatible with the principles of subversive rationalization proposed by Black radical critique. Tipo: Dissertação 2025-10-24T00:00:00Z