https://repositorio.ufu.br/handle/123456789/5145 2026-09-13T15:00:59Z 2026-09-13T15:00:59Z https://repositorio.ufu.br/handle/123456789/50188 2026-09-10T06:21:01Z 2026-08-06T00:00:00Z

Title: Uma análise da proteção de sobrecorrente com restrição por tensão (51V) em contexto da minigeração distribuída Abstract: The increasing integration of distributed minigeneration into distribution networks changes the behavior of power systems during faults and creates new challenges for overcurrent protection. In installations with inverter-based sources, the limitation of the current supplied by power converters may hinder the operation of conventional protection functions, requiring the assessment of alternatives that consider additional electrical quantities. In this context, this study analyzes the application of ANSI function 51V, voltage-restrained overcurrent protection, in networks with distributed generation connected at medium voltage. The study comprises an overview of the protection functions associated with the connection of generating facilities, a literature review concerning the application of function 51V, and an analysis of the technical documents adopted by Brazilian distribution utilities. Additionally, simulations were performed in MATLAB/Simulink to evaluate voltage and current behavior under different fault conditions, as well as the sensitivity of functions 51 and 51V. The results showed that the combined analysis of these quantities provides a more comprehensive characterization of fault conditions. In cases where the current contribution from the generating facility remained limited, conventional function 51 showed difficulty in reaching its operating threshold, whereas voltage restraint reduced the operating threshold of function 51V and enabled the identification of conditions not detected through overcurrent alone. Nevertheless, its response remained dependent on voltage-sag severity, fault characteristics, and the selected settings. Accordingly, function 51V proved to be a complementary alternative for improving protection sensitivity in networks with inverter-based generation, especially when fault current is limited by power converters. However, its application requires system-specific studies and coordination with other protection functions.

2026-08-06T00:00:00Z https://repositorio.ufu.br/handle/123456789/50161 2026-09-09T06:18:11Z 2026-04-08T00:00:00Z

Title: Análise bibliométrica do emprego de metodologias ágeis na engenharia eletrônica: o caso do desenvolvimento de softwares Abstract: This paper presents a bibliometric analysis of the use of agile methodologies in Electronic Engineering, focusing on software development, and investigates the influence of artificial intelligence (AI) in this context. The study was conducted based on 173 scientific articles published between 2000 and 2025, extracted from the Web of Science, and analyzed using tools such as VOSviewer and Bibliometrix. The results reveal that Scrum is the most widely used agile framework, standing out for its flexibility in complex projects, such as embedded systems. The integration of AI has shown promise, with tools such as Jira and GitHub Copilot optimizing processes such as test automation and code generation. However, ethical and technical challenges, such as algorithmic bias and the potential erosion of human collaboration, require attention. The adoption of agile methodologies in Electronic Engineering is still in its infancy compared to pure software development, due to barriers such as hardware-software integration and strict compliance requirements. The analysis identified gaps in literature, such as the scarcity of studies on agile in hardware and highly regulated environments, as well as opportunities for future research, such as the combination of agile with DevOps and IoT. This work contributes to the field by mapping the scientific literature on the topic, highlighting emerging trends, and proposing directions for further research. Limitations include the restriction to specific databases and the quantitative nature of the analysis, suggesting the need for complementary qualitative studies.

2026-04-08T00:00:00Z https://repositorio.ufu.br/handle/123456789/50147 2026-09-05T06:22:06Z 2026-07-07T00:00:00Z

Title: Simulação Monte Carlo em irradiação de corpo inteiro: validação de feixe clínico e avaliação dosimétrica em objetos antropomórficos virtuais adulto e infantil Abstract: Radiotherapy plays a pivotal role in the management of cancer and is indicated for a substantial proportion of patients, with curative, adjuvant, or palliative intent. Among its applications, Total Body Irradiation (TBI) stands out as an integral component of conditioning regimens for bone marrow transplantation, especially in patients with acute myeloid leukemia (AML). However, TBI presents specific dosimetric challenges related to the large extent of the irradiated volume, anatomical heterogeneity, and the need for dose homogeneity throughout the patient's body. In this context, the present study aimed to develop and validate, using the Monte Carlo (MC) method with the MCNP 6.3 code, a computational model of the 6 MV clinical beam from a VersaHD linear accelerator and apply it to the simulation of a TBI scenario with a long source to-surface distance (SSD). The dose distribution in adult and pediatric anthropomorphic MRCP mesh phantoms of both sexes, developed by the ICRP, was evaluated. The modeling included the implementation of a phase-space-based virtual source already described in the literature, as well as the geometric representation of the collimation system (MLC and backup jaws). Model validation was performed by comparing simulated results with experimental data, using percentage-depth dose (PDD) curves, beam profiles at different depths, and the TPR20,10 beam quality index. Agreement within clinically acceptable limits was observed, with percentage differences on the order of 3% for the reference field, 10 × 10 cm². After beam validation, the model was applied to the simulation of the TBI scenario, allowing the estimation of the absorbed dose in organs at risk and the comparison of the dose distribution between pediatric and adult models of the MRCP phantoms. The results show variations associated with anatomical and dimensional differences between the phantom objects, highlighting the importance of individualized approaches in dose estimation for each patient. It is concluded that the developed model demonstrated dosimetric robustness and clinical applicability, proving to be a reliable tool for dose distribution analysis in TBI and contributing to the improvement of the characterization of radiotherapy beams in complex scenarios.

2026-07-07T00:00:00Z https://repositorio.ufu.br/handle/123456789/50146 2026-09-05T06:22:05Z 2026-08-05T00:00:00Z

Title: Análise comparativa do torque em atuadores robóticos acionados por controle de 6 passos e controle por orientação de campo (FOC) aplicados à reabilitação de membros superiores Abstract: Loss of upper-limb motor function, often resulting from stroke, is one of the main challenges in physical rehabilitation, and assistive robotics has emerged as an alternative for delivering more intensive, consistent, and measurable therapy. In this context, the control strategy adopted by the electric actuator directly affects the quality of the torque delivered to the patient. This work aims to compare the performance of two driving techniques for permanent magnet synchronous motors (PMSM) — six-step commutation and Field-Oriented Control (FOC) — with respect to torque generation, within the context of a robotic rehabilitation platform for the upper limbs inspired by the MIT-Manus. Both strategies were modeled and compared in a MATLAB/Simulink environment; in parallel, a custom outrunner PMSM (14 pole pairs) and a dedicated driver built around the STSPIN32G4 system-in-package were developed, and the experimentally identified electrical parameters of the physical motor were incorporated into the simulation model for a higher-fidelity validation. Results showed that, for an equivalent average torque (approximately 1.03 N.m), FOC produced a peak-to-peak torque ripple of 0.323 N.m (31.4 \%), about 4.8 times lower than that observed with six-step commutation (1.547 N.m, 150.1 \%), along with a superior speed dynamic response. It is concluded that FOC is the most suitable control strategy for rehabilitation applications requiring smooth and precise torque delivery, with physical experimental validation of the prototype remaining as the next development step.

2026-08-05T00:00:00Z