https://repositorio.unifei.edu.br/jspui/handle/123456789/87 2026-06-13T07:16:23Z 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/123456789/4438 Título: Estudo das interações intermoleculares de ciclodextrinas com fármacos antidiabéticos Abstract: Metformin hydrochloride (MET) and phenformin hydrochloride (FEN) are antihyperglycemic drugs belonging to the biguanide class, with MET being a first-line therapy for the treatment of type II diabetes mellitus (DMII). MET is limited by its low bioavailability, whereas FEN was withdrawn from the market due to adverse side effects associated with its use. Cyclodextrins (CDs) are of great interest to industry, particularly the pharmaceutical sector, because of their ability to modify intrinsic drug properties such as solubility, stability, and bioavailability. The aim of this study was to investigate the thermodynamic parameters involved in the interactions between the drugs FEN and MET and natural cyclodextrins (α-CD, β-CD, and γ-CD), as well as modified cyclodextrins (CM-β-CD, HP-β-CD, and M-β-CD), and to structurally characterize the compounds formed. Thermodynamic parameters were determined using isothermal titration calorimetry (ITC); additionally, the effect of temperature variation was evaluated for the FEN:CM-β-CD system. Solid-state inclusion compounds were obtained by freeze drying. The inclusion compounds were characterized by vibrational spectroscopy in the infrared region (FTIR-ATR), and inclusion was confirmed by one- and two-dimensional 1H NMR experiments. By comparing the systems formed by MET and FEN using calorimetric titration, it was possible to verify that the presence of an aromatic ring in the FEN structure favored the formation of inclusion compounds with α-CD, β-CD, and CM-β-CD. Based on the 1H NMR results, the formation of inclusion compounds was confirmed for the FEN:β-CD and FEN:CM-β-CD systems, and possible structures for the complexes formed were proposed. Tipo: Dissertação 2026-03-13T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4437 Título: Otimização da geometria do sistema de gases dos fuzis IMBEL IA2 utilizando métodos de delineamento de experimentos aplicados a simulação DFD Abstract: This work presents a geometric optimization study of the gas system of the IMBEL IA2 rifles using Computational Fluid Dynamics (CFD) combined with Design of Experiments (DOE) methods. The IA2 operating system, responsible for diverting part of the propellant gases from the barrel and converting them into mechanical energy for weapon cycling, was originally dimensioned through empirical procedures. Considering the absence of gas regulation in the current design and the requirement for high reliability under different operational conditions, a detailed understanding of the transient flow phenomena inside the system becomes essential. Experimental tests were conducted by instrumenting the rifle with pressure transducers, enabling the acquisition of real pressure curves inside the barrel and gas cylinder. High-speed camera recordings were also performed to determine the displacement–time curve of the bolt carrier. These experimental data were used to validate a two-dimensional transient numerical model with dynamic mesh and moving wall motion equation implemented in ANSYS Fluent. After validation of the baseline configuration, a factorial design was applied to evaluate the influence of relevant geometric parameters, in this case gas port diameter and initial gas cylinder length, on objective functions related to peak pressure, peak time, and total impulse delivered to the system. An analysis of variance (ANOVA) was performed, and response surfaces were generated for each objective function, enabling the identification of the most influential parameters. Finally, alternative geometries were proposed and assessed, including the addition of a relief orifice and a pressure accumulation chamber. The results indicate that it is possible to delay and smooth the pressure curve inside the gas cylinder, reducing peak pressure without compromising the total impulse required for proper cycling. The study provides technical support for the optimization of the IA2 gas operating system and for the development of future IMBEL firearms, contributing to improved reliability and reduced experimental effort during the design process. Tipo: Dissertação 2026-03-30T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4436 Título: O impacto da organização do trabalho e suas implicações nas condições de saúde no comércio varejista de móveis e eletrodomésticos na cidade de Itajubá MG Abstract: This research investigates the impact of work organization on productivity management and predictors of illness in the retail sector. The study aimed to analyze the configuration of work processes, the impact of online sales on in-person sales, and the risks to worker health. Methodologically, a qualitative, descriptive, and exploratory approach was adopted, based on the theoretical framework of Ergology and the methodological framework of the Collective Subject Discourse (CSD). After ethical approval, open interviews were conducted with salespeople, whose data were processed using the MAXQDA software. The analysis revealed ten central categories: Individualization, Inefficiency/Bureaucratization, Resignation, Instability/Insecurity, Pressure, Overload, Helplessness, Invisibility, Recognition, and Blaming. The results highlight the prevalence of Pressure and Overload, simultaneously evidencing movements of renormalization among salespeople as a strategy for preserving health and adapting to the environment. The findings confirm that the management model based on goals undermines health, generating physical and mental exhaustion in 100% of the sample and the use of psychotropic drugs in 40%. It is concluded that neoliberal logic and technological innovations intensify professional instability and transform the worker into a disposable resource, where competitiveness replaces solidarity and illness is silenced by individual blame. The urgency of a management model that prioritizes human value over sales metrics to mitigate occupational burnout is highlighted. Tipo: Dissertação 2025-12-08T00:00:00Z