https://repositorio.unifei.edu.br/jspui/handle/123456789/55 2026-05-23T16:55:51Z https://repositorio.unifei.edu.br/jspui/handle/123456789/3173 Aquisição e validação de sinal de ruído eletroquímico 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. Dissertação 2022-02-17T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4402 Avaliação técnico econômica e ambiental da planta de produção de hidrogênio usando fontes renováveis (H2V): diagnóstico, otimização, avaliação dos impactos ambientais Population growth and industrialization present the challenge of providing more energy with fewer greenhouse gas emissions. In this context, hydrogen stands out as one of the most promising energy carriers, in addition to being essential for the production of ammonia, methanol, steel, glass industry products, among others. This study aims to analyze the technical, economic, and environmental potential of hydrogen production from renewable energy sources in the state of Minas Gerais. The first process analyzed was biomass residue gasification. For this, the 66 microregions of Minas Gerais were considered in the analysis of nine selected types of residues, under different gasifying agent conditions and with the possibility of gas upgrading. A chemical equilibrium model based on Gibbs free energy minimization was developed for this purpose, validated under gasification conditions with air, pure oxygen, and air-steam mixtures. Additionally, a Monte Carlo simulation was applied for the economic analysis, along with a life cycle assessment (LCA) of the gasification process. The second process evaluated was proton exchange membrane (PEM) electrolysis powered by renewable sources. The electrolysis process was modeled and, after model validation, sensitivity analyses were carried out to determine the operating points that maximize hydrogen production. With the maximum production points defined for both the electrolysis and gasification processes, an economic analysis was performed using the Levelized Cost of Hydrogen (LCOH) as a metric. The main results indicated that, in the case of gasification, the highest theoretical hydrogen production potential in Minas Gerais was obtained from sugarcane residues, representing 82% of the total. Only nine microregions concentrated about 80% of this potential. The economic potential was evaluated under three residue collection and usage scenarios, with Frutal and Uberaba standing out as the regions with the best economic prospects, reaching LCOH values below US$3/kg of hydrogen under optimistic waste utilization conditions across all gasifying agent scenarios. In the Monte Carlo simulation, the input parameters that most influenced the LCOH in gasification were: minimum attractive rate of return (MARR), residue recovery factor, capital expenditures (CAPEX), Chemical Engineering Plant Cost Index (CEPCI), and local taxes. The life cycle assessment indicated that using the purge gas from the PSA (Pressure Swing Adsorption) process in gasification is environmentally necessary, and that the process emissions were below 2.44 kgCO₂eq/kgH₂, which is considered low according to Law 14,948 of 2024, from the Brazilian code. For electrolysis, it was found that hydrogen purity requirements considerably increase the levelized cost. Furthermore, the addition of electrolysis modules showed a more significant economy of scale effect at lower production capacities. It was also found that self-generation of electricity cannot compete with auction-based tariffs from the same renewable sources (solar and wind), as these benefit from economies of scale, resulting in lower costs. Tese 2025-04-23T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4401 Avaliação técnico econômica e ambiental da planta de produção de hidrogênio usando fontes renováveis (H2V): diagnóstico, otimização, avaliação dos impactos ambientais Population growth and industrialization present the challenge of providing more energy with fewer greenhouse gas emissions. In this context, hydrogen stands out as one of the most promising energy carriers, in addition to being essential for the production of ammonia, methanol, steel, glass industry products, among others. This study aims to analyze the technical, economic, and environmental potential of hydrogen production from renewable energy sources in the state of Minas Gerais. The first process analyzed was biomass residue gasification. For this, the 66 microregions of Minas Gerais were considered in the analysis of nine selected types of residues, under different gasifying agent conditions and with the possibility of gas upgrading. A chemical equilibrium model based on Gibbs free energy minimization was developed for this purpose, validated under gasification conditions with air, pure oxygen, and air-steam mixtures. Additionally, a Monte Carlo simulation was applied for the economic analysis, along with a life cycle assessment (LCA) of the gasification process. The second process evaluated was proton exchange membrane (PEM) electrolysis powered by renewable sources. The electrolysis process was modeled and, after model validation, sensitivity analyses were carried out to determine the operating points that maximize hydrogen production. With the maximum production points defined for both the electrolysis and gasification processes, an economic analysis was performed using the Levelized Cost of Hydrogen (LCOH) as a metric. The main results indicated that, in the case of gasification, the highest theoretical hydrogen production potential in Minas Gerais was obtained from sugarcane residues, representing 82% of the total. Only nine microregions concentrated about 80% of this potential. The economic potential was evaluated under three residue collection and usage scenarios, with Frutal and Uberaba standing out as the regions with the best economic prospects, reaching LCOH values below US$3/kg of hydrogen under optimistic waste utilization conditions across all gasifying agent scenarios. In the Monte Carlo simulation, the input parameters that most influenced the LCOH in gasification were: minimum attractive rate of return (MARR), residue recovery factor, capital expenditures (CAPEX), Chemical Engineering Plant Cost Index (CEPCI), and local taxes. The life cycle assessment indicated that using the purge gas from the PSA (Pressure Swing Adsorption) process in gasification is environmentally necessary, and that the process emissions were below 2.44 kgCO₂eq/kgH₂, which is considered low according to Law 14,948 of 2024, from the Brazilian code. For electrolysis, it was found that hydrogen purity requirements considerably increase the levelized cost. Furthermore, the addition of electrolysis modules showed a more significant economy of scale effect at lower production capacities. It was also found that self-generation of electricity cannot compete with auction-based tariffs from the same renewable sources (solar and wind), as these benefit from economies of scale, resulting in lower costs. Tese 2025-04-23T00:00:00Z https://repositorio.unifei.edu.br/jspui/handle/123456789/4399 Mudanças climáticas e saúde mental: percepção e memória de pessoas idosas de Santa Rita do Sapucaí Population aging is a growing reality on a global scale and poses significant challenges to public policies, especially regarding the protection of mental health in later stages of life. Throughout aging, specific physical, emotional, and social conditions emerge that, in certain environmental contexts, influence coping mechanisms. Simultaneously, climate change is intensifying, with its impacts becoming more frequent and severe, disproportionately affecting territories marked by socio-environmental inequalities where older people construct their life trajectories and aging processes. In this context, this study aimed to understand how older people perceive and psychologically experience ongoing climate change, investigating its impacts on the mental health of the elderly population in the municipality of Santa Rita do Sapucaí, in southern Minas Gerais, a region characterized by the recurrence of extreme weather events, such as floods. It is based on the understanding that the intersection between population aging and climate change exacerbates vulnerability, demanding coordinated responses from different sectors of public policy. A qualitative approach was adopted, based on the Collective Subject Discourse method, using interviews conducted with elderly residents of the municipality. The analysis of the discourses allowed for the identification of emerging categories that express shared meanings, emotions, and interpretations about the climate phenomenon. The results indicate that climate change is perceived as a concrete and progressive process, associated with the loss of climate predictability, the recurring fear of new extreme events, and an increased feeling of insecurity and helplessness. Manifestations of psychological distress are observed, such as anxiety, constant worry, and fear, frequently anchored in previous experiences with floods and in the memory of a past climate perceived as more stable. These narratives reveal the formation of a collective climate memory, in which recollections of extreme events and past environmental transformations shape the current perception of risk and guide ways of coping with and giving meaning to suffering. Furthermore, the fragility of local public policies in the psychosocial care of the elderly population in contexts of climate risk is evident. It is concluded that climate change significantly impacts the mental health of the elderly population, articulating emotional, social, and symbolic dimensions of aging. The study highlights the need for public policies that integrate mental health, climate justice, and social protection, recognizing older people as central actors in the processes of adaptation to and coping with climate change, with strategies sensitive to territory, memory, and socio-environmental inequalities. Dissertação 2026-02-10T00:00:00Z