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Computational tool to evaluate the efficency of hydrogen in internal combustion engines
(Universidade Federal de Lavras, 2025-03-20) Rincon, Alvaro Ferney Algarra; Alvarez, Carlos Eduardo Castilla; Ensinas, Adriano Viana; Rodriguez, Christian Jeremi Coronado
Behavioral studies on the efficiency of a hydrogen engine are important, as they are part of a global initiative to decarbonize the automotive sector, and this technological route for the use of hydrogen is promising within recent energy transition studies. In this sense, the exploration of new technological development routes around production, commercialization and use of hydrogen for the state of Minas Gerais and for Brazil has been proposed through various government initiatives in recent years. For this reason, this work has developed a computational tool based on a zero-dimensional mathematical model capable of predicting the efficiency of a spark ignition engine when using hydrogen as fuel. The simplicity of the model offers a quick view of the operation and thermodynamics of the engine, which reduces computational effort and produces results that represent the real behavior of hydrogen combustion. This focus helps in the study of combustion and in making decisions about the economic viability of using hydrogen in internal combustion engines. To do this, the compression, combustion and expansion processes in the Otto cycle were mathematically modeled to represent the combustion behavior of the air-hydrogen blend inside the engine cylinder, using code written in MATLAB. The mathematical model was validated with experimental data taken from the research engine bench and those reported in the literature in relation to the pressure curve for the different engines and operating conditions evaluated, and the efficiency produced by the engine under these conditions was estimated. A graphical interface was generated in AppDesigner for the computational tool, making it easier for the user to develop the behavioral and operational study of a hydrogen engine. The results obtained with the computational tool show that the estimated pressure and efficiency values are in good agreement with those found in the literature in all the cases evaluated. The maximum error when comparing the pressure curve was 1.32% for an engine with a speed of 3300 RPM. In addition, the minimum fit of the mathematical model to the experimental data was 86%, which represents a good alternative for estimating the thermal efficiency value.
Sementes de milho popped kernel e furadas: armazenabilidade e classificação de defeitos por meio de algoritmos de aprendizado de máquina
(Universidade Federal de Lavras, 2026-05-19) Briceño Pinzon, Ivan David; Pires, Raquel Maria de Oliveira; Carvalho, Everson Reis; Silva, Laercio Junio da; Andrade, Dayliane Bernardes de; Lima, Renato Ribeiro de; Nery, Marcela Carlota
Corn is one of the most widely produced crops in the world, with great economic and nutritional importance. The seed, as a raw material, is responsible for transferring the advances of genetic improvement, guaranteeing high yields under proper management. Its quality integrates physical, physiological, genetic, and sanitary attributes, forming the basis of the crop's productive potential. However, biotic and abiotic stresses can reduce their quality, favoring the emergence of defective seeds such as popped kernel (PK) and perforated seeds. The objective of this study was to evaluate the physiological quality of corn seeds with PK and perforated defects during storage, as well as to assess the ability to classify these defects using supervised machine learning algorithms. Samples containing five defect ratios (0%, 2,5%, 7,5%, 15% e 25%) were stored under ambient conditions. Physiological quality assessments were performed at baseline and every three months, up to nine months for PK seeds and 12 months for samples with a perforated defect. Images of defective and healthy seeds were captured, and after processing, four supervised learning models and the GroundEye system were used for classification. It was observed that proportions higher than 2.5% for perforated seeds and 7.5% for PK seeds compromise germination and vigor after 3 and 6 months of storage, respectively. The MLP (Multi-Layer Perceptron) and SVM (Support Vector Machine) models demonstrated accuracies above 82% for samples containing perforated seeds and 96% for the prediction of PK seeds, respectively. On the other hand, the GroundEye system, using a reduced number of variables selected by the Kruskal–Wallis method, demonstrated good classification performance, with an accuracy of 98%. Tolerance levels for the presence of defective seeds were determined for each defect without compromising the physiological potential of the seeds. Image-based methodologies can assist laboratory analyses, providing accurate results and reducing subjectivity.
Composto de café e yacon obtido por secagem em camada de espuma
(Universidade Federal de Lavras, 2026-02-25) Marques, Matheus Robim; Correa, Jefferson Luiz Gomes; Figueiredo, Luisa Pereira; Macedo, Leandro Levate; Nascimento, Bruna de Souza; Nascimento, Bruna de Souza
The search for functional foods has been increasing in Brazil, mainly due to the growing interest in bioactive properties capable of supporting metabolic and physiological functions in the body. These compounds are sensitive and degrade through various reactions that occur within the food matrix. In this context, drying emerges as an important preservation method. Among the available techniques, foam mat drying (FMD) is a valid alternative, as it operates at lower temperatures and requires shorter drying times compared to other conventional methods. The objective of this study was to evaluate the potential of FMD technology by investigating the influence of the foaming agent (albumin and whey protein) and drying temperature (50 and 70 °C) on the physicochemical characteristics and functional potential of powders obtained from a mixture of coffee extract and yacon juice. The foams were optimized for density using two central composite rotational designs (CCRD) and were subjected to drying in a convective air tunnel. Drying kinetics were evaluated, and the resulting powders were analyzed for moisture content, hygroscopicity, solubility, water activity, total phenolic content, and fructan retention. Increasing the drying temperature from 50 to 70 °C resulted in reduced drying time and greater solubility and hygroscopicity of the powders. A reduction in total phenolics and fructans was also observed after drying, attributed to thermal sensitivity of the compounds and oxygen exposure. However, formulations dried at 70 °C, especially those containing albumin, showed higher values of total phenolics and fructans compared to the other treatments.
Farmacocinética da progesterona exógena e seus efeitos no trato reprodutor de éguas
(Universidade Federal de Lavras, 2026-02-12) Nunes, Karine Rabelo de Oliveira; Palhão, Miller Pereira; Ferrante, Marcos; Palhão, Miller Pereira; Ferrante, Marcos; Araújo, Reno Roldi de
Progesterone (P4) plays a key role in establishing uterine receptivity for early maintenance ofpregnancy and is widely used pharmacologically in hormonal protocols to prepare recipientmares in embryo transfer programs. Despite its routine use, information regarding thepharmacokinetics of exogenous P4 in acyclic mares remains limited, particularly amongdifferent formulations. The objective of this study was to characterize the pharmacokineticprofile of exogenous injectable P4 administered at two doses (900 mg and 1500 mg) and as avaginal implant (1 g), as well as to evaluate its effects on uterine edema and tone. Serial bloodsamples were collected for P4 quantification by ultra-performance liquid chromatographycoupled with tandem mass spectrometry (UPLC–MS/MS), and pharmacokinetic analysis wasperformed using a non-compartmental model. Daily reproductive tract evaluations wereconducted by ultrasonography and rectal palpation. The 1500 mg dose resulted in a highermaximum plasma concentration and longer systemic persistence, maintaining levels above 2.5ng/mL for more than 216 hours, whereas the 900 mg dose maintained adequate concentrationsfor less than 24 hours. The vaginal implant promoted rapid absorption, maintainingconcentrations close to the minimum threshold for approximately 72 hours. Greater systemicpersistence and prolonged half-life were observed in lighter mares. A progressive reduction inuterine edema and an increase in uterine tone was observed in all treatments, characterizing aprogesterone-influenced uterine environment. In conclusion, the pharmacokinetics ofexogenous P4 in mares are dependent on both formulation and dose. The vaginal implantappears suitable for short-term protocols, whereas the 1500 mg injectable progesteroneformulation is appropriate for prolonged maintenance, although it may impair recipient mareresynchronization.
Proposta de classificação quanto ao dano potencial associado para barragens em cascata
(Universidade Federal de Lavras, 2026-02-26) Silva, Milena Cristina de Paula Carvalho e; Cândido, Eduardo Souza; Ribeiro, André Geraldo Cornélio; Teixeira, Emmanuel Kennedy da Costa
The failure of dams represents one of the highest-risk scenarios associated with hydraulic infrastructure, particularly when these structures are arranged in cascade along the same watercourse. Despite the relevance of this topic, the criteria currently adopted in Brazil for classification regarding potential associated damage (DPA), established within the framework of the National Dam Safety Policy (PNSB), consider dams individually, without explicitly addressing the cumulative effects and hydrodynamic interactions between interconnected structures. In this context, this study aims to evaluate the hydrodynamic behavior of flood waves resulting from the hypothetical failure of dams arranged in cascade, as well as to propose new classification criteria for DPA under such scenarios. To this end, nine sets of earthfill dams for water storage were analyzed, representing different combinations of upstream and downstream dam sizes. The failure simulations were carried out using two-dimensional hydrodynamic modeling in the HEC-RAS software, considering four hydrological scenarios: no precipitation and precipitation events associated with return periods of 500, 1,000, and 10,000 years. The results were analyzed based on maximum depth, velocity, and hydrodynamic hazard maps of the floodplain, and the methodology proposed by Smith et al. (2014) was also considered. The results showed that, in several scenarios, small upstream dams had their impacts attenuated by downstream dams, whereas certain volume combinations led to a significant intensification of hydrodynamic risk, highlighting the importance of integrated assessment. The findings indicate that analyzing dams individually may underestimate or overestimate the associated potential damage, reinforcing the need for specific criteria for cascade dam systems. Thus, this study contributes to the improvement of risk assessment practices and dam classification, providing technical support for a more representative approach to the impacts associated with cascade systems.