This work aims to contribute to the development, understanding, and advancement of damage detection in composite materials using the technique of vibrothermography. This technique, classified as an active infrared thermography technique, uses vibrations to add energy to the system and thermal mapping of the material's surface to identify temperature profiles or gradients that indicate the possibility of internal damage to the structure. In the search for innovation in numerical analysis applied to the subject, the formulation proposed to evaluate the viscoelastic response of the material was applied, making it possible to detect the damage induced at the interface between the Prepreg and Rohacell Hero 71\textregistered materials. The change in the temperature profile generated on the surface of the material after numerical analysis of the structure made it possible to detect points with greater temperature gradients, such as the crimping region, the force application region and the region where the damage was inserted. In addition to the initial numerical analysis carried out for sinusoidal excitation, experimental tests were carried out to evaluate the generation of internal heat in the structure during excitation. At this stage, the use of different frequencies (natural and unnatural) and different types of signals (composed of sine, triangular or square waves) proposed to investigate the presence of damage in the sandwich beam were evaluated, obtaining different responses for the combinations used. A higher rate of internal heat generation was observed for excitation using the square type signal and lower for triangular type excitation. The measurement of the accelerations at the reference points defined in the test plan, together with the analysis of the thermograms generated for the different combinations, made it possible to verify, for the damage region, greater heat exchange between the beam and the environment when excited at a frequency of 545.65 Hz. At 938.96 Hz, for the damaged region, the lower energy exchange between the beam and the environment and the greater generation of internal heat when compared to the same undamaged region led to a change in the temperature profile, indicating the possibility of damage.

With the growing energy demand, the rise of stricter environmental regulations, and the large-scale application of electric vehicles far from being a reality, new energy vectors for internal combustion engines have been considered. In this sense, biogas, biomethane, and syngas represent options that deserve some attention, despite not being widely used in Brazilian transportation. In addition to the use of new energy sources, innovative techniques – such as the dual fuel mode – can improve even further the potential of different fuels, such as HVO (hydrotreated vegetable oil), in order to optimize the engine operation in terms of efficiency and pollutants emissions. Therefore, the present thesis proposes experimental and numerical analyses in a single-cylinder diesel engine operating in dual fuel mode with fuels adaptable to the Brazilian energy matrix. The potential of theses fuels as partial replacements for diesel was verified, reducing NOx (up to 25.8%) and particulate matter (up to 86%) emissions, associated to a small decrease in thermal (up to 12.5%) and combustion (up to 4.2%) efficiencies. When diesel was replaced by HVO, improvements were observed in both emissions (NOx, CO, CO2, HC and particulate matter) and thermal efficiency. Finally, the combination of gaseous fuels with HVO led to the same trend observed for diesel, but with superior results for efficiency and emissions. In all the studied cases, the ANSYS Forte® CFD model offered additional understanding of experimental results, representing an option for extrapolation of results, optimization, and prediction of engine operation without the need of additional tests.

Faced with an increasingly competitive and demanding market, steel producers of stainless steel have been developing increasingly resistant and cost-effective products for recommended applications. These steels enjoy a favorable scenario for applications in the most varied fields of engineering. However, there is a lack of information regarding the impacts of the welding process parameters on the final quality of the weld bead. Thus, the objective of this work is to evaluate the influence of the welding heat input on the microstructure of the heat-affected zone (HAZ) of Endur 300 commercial stainless steels. is necessary in order to guarantee that both the phase balance and the mechanical properties of the material are not severely impaired in a subsequent application. The work comprises the characterization of the HAZ of welded joints using the GMAW (Gas Metal Arc Welding) process with thermal inputs of 4.2, 6.7 and 9.1 kJ/cm. Welding was carried out in the three chosen thermal inputs, and then proceeded to the analysis of the base metal and weld beads through Vickers Microhardness tests, traction, 180° guided bending, macroscopy, optical microscopy (OM), fracture analysis (SEM) ending with  phase quantification via software. The results showed that the natural cooling rate of the three conditions tested was not enough to cause significant microstructural changes in the balance of the Ferrite and Martensite phases found in the HAZ. Regarding the
mechanical properties, the change in heat input also did not impact the final quality of the welded joints.

In the aeronautical sector, a type of geometry widely used in studies in aerodynamics are the high lift devices. These bodies located on the leading and treailing edges of the aircraft’s wings are responsible for increasing lift, for example, during takeoff and landing where the aerodynamic conditions are different, the wings need these devices to obtain the necessary lift coefficient. This work presentes a study of the flow dynamic involving the aerodynamic airfoil NACA0012 with and without high lift devices, where the objective is to have a better understanding of the effects involved and to define among the evaluated geometries, the one with the best performance in maximixing lift and reduce drag. For the numerical studies, the Navier-Stokes equations were solved to obtain the results using the COMSOL Multiphysics software, which is based on the Finite Element Method. All simulations were carried out in the Heat Transfer Laboratory (LabTC) on the Federal University of Itajubá. Initially, the simulations were performed on the NACA0012 airfoil, called the base airfoil, and then a flap at 10° was added to its trailing edge. It was observed that the addition of the flap generates an increase in the values of the lift and drag coefficients for the same angle of attack. A third test was carried out for the base airfoil with the addition of the flap, where the base airfoil was fixed at 7° and the flap angle was varied, showing that as the angle increases the lift coefficient also increases, this occurs due to the increased curvature of the airfoil. Another simulation performed was adding a slat on the leading edge, proving the this device postpones the stall. Finally, a test was carried out adding a slat and a flap to the base airfoil, stating that the combination of these three elements generates a higher value of the lift coeficiente and a better distribution of the pressure coeficiente. Based on the angle of attack variation, it were performed qualitative and quantitative analyzes of the results of the streamline fields, vorticity fields, pressure fields and aerodynamic coefficients for a Reynolds number equal 1000.

Aluminum alloys are widely used in the aeronautical, automobile, construction and consumer goods industries, mainly due to their low density and high resistance to corrosion. Research aimed at recycling and reuse has increased over the years, and is within SDG objectives 9 and 12. However, one of the greatest difficulties encountered during recycling is the impurity of the iron element, which when present forms phases rich in this element, which are coarse and harmful, which impair the mechanical properties. Therefore, this work aims to analyze the effect of different iron contents on the density and microhardness of alloy 7075 produced by the high-energy grinding/powder metallurgy process from chips. For this, 7075-T6 alloy chips were ground for 40 hours at 400 rpm, then sieved and mixed in a mill for 2 hours at 250 rpm with 2, 4 and 6% by weight of iron. For compaction, values of 400 MPa and 700 MPa were used in a uniaxial press and 250 MPa in an isostatic press, while the sintering time used was 60 and 120 minutes for temperatures of 500°C and 600°C. The density and microhardness results were measured and analyzed using the planning of experiment (DOE) in the Minitab® software, through which it was possible to verify the optimal parameters for each iron addition condition and create mathematical formulas for the density and microhardness, as well how to evaluate the effect of each parameter on the responses. The best sample was produced with the addition of 4% iron, pressure of 700 MPa in the uniaxial press and 250 MPa in the isostatic press, the temperature and sintering time used were 600°C and 60 minutes respectively, with this condition obtaining an average microhardness. of 107.5 HV and density of 2.58 g/cm3.

Aeroderivative gas turbines are widely used on Floating Production Storage and Offloading (FPSO) oil and gas production platforms. These units serve as production, storage, and oil transfer facilities. These turbines are employed either for generating electrical power when connected to an electrical generator or for mechanically driving pumps and compressors when connected to these machines. Oil and gas production is intermittent and demands gas turbines to be available and flexible for safe and reliable operation. To achieve such conditions, monitoring them is a crucial factor to ensure operational safety. Another factor is diagnosing turbine faults, efficiently and reliably identifying where these faults are occurring, so that maintenance planning is effective in keeping the machine operational. In this context, the primary objective of this work is to develop a method to assist in diagnosing faults that affect the performance of aeroderivative gas turbines. To achieve this, a model of an aeroderivative gas turbine, consisting of a two-spool gas generator and a power turbine (PT), was developed using MATLAB/Simulink with the assistance of the T-MATS library. The developed model can represent the behaviour of the gas turbine when operating in a steady-state since the goal is to generate data for different operating conditions and different environmental conditions for subsequent use in a neural network model. The gas turbine model exhibited satisfactory behaviour, with deviations not exceeding 1% when compared to actual operational data. Subsequently, fault conditions were imposed on the model, which provided information about operational parameters of the turbogenerator operating with degradation in some of its components. The data generated by the gas turbine model in MATLAB/Simulink were used to feed a machine learning model for fault diagnosis. The proposed model consists of two parallel feedforward neural networks, one for regression and one for classification. The regression network aims to handle numerical values and the turbine's behaviour, while the classification network aims to identify and classify faults. Both networks performed well for both single and combined fault problems, with mean squared errors not exceeding 5x10-6 for the regression network and a percentage error of 0.37% for the classification network.

The use of composite materials in the most varied industrial sectors has increased considerably in recent years, especially those reinforced with bidirectional carbon fiber/epoxy resin fabrics. These, in the most varied applications in which they are used, experience several types of possible requests, one of them being compression requests. With this increasing use and reports of failures in structures, when submitted to compression requests, there is a need to better understand their behavior when exposed to this type of request. In this context, an experimental set of data to measure damage progression, considering cyclic loads in compression of a bidirectional composite laminate, is presented, involving static and fatigue mechanical characterization, identification of the fatigue deformation limit for lives up to 120,000 cycles and 240,000 cycles, damage mapping through damage parameters extracted from hysteresis cycles, deformation gradient data extracted by Digital Image Correlation (DIC), temperature data obtained by a thermographic camera, characterization of failure modes, and results of a study on the failure mechanisms, performed by scanning electron microscopy (SEM). Although many studies have been reported in the literature on damage progression in composite materials, very few have focused on the analysis of compression fatigue in bidirectional composites using analytical, numerical, and experimental analyses. Thermography proved to be useful in the rapid assessment of fatigue damage and in determining the fatigue strength limit. By obtaining the hysteresis cycles, a mapping of the damage progression for stresses close to the deformation limit was carried out, using the accumulated damage index, loss fator, and stiffness degradation. With the deformation maps obtained by DIC, it was observed that the deformations are not uniform along the surface of the sample, showing that the composite material exhibits an intrinsic mechanical heterogeneity. Finally, fractographic aspects of the fracture surfaces of samples from static, fatigue, and hysteresis tests were analyzed by scanning electron microscopy. The analyses showed that the fracture surfaces were rich in fractographic aspects, and how important is the use of this tool for understanding how the combination of different failure mechanisms interacts and leads to failure of the composite material.

Seas and oceans provide a clean and renewable energy source widely accessible near major consumption centers. This source offers a valuable option in the energy transition and decarbonization process. Wave energy, along with the Oscillating Water Column (OWC) onshore device, is one of the most prominent forms of ocean energy. The implementation of this device requires locations with rocky outcrops and a steeper slope to ensure the physical installation and reduce energy dissipation due to friction with the seabed. Brazil has approximately 7,490 km of coastline with varied coastal geometries and geomorphologies, some highly suitable for OWC installation. It is estimated that the Brazilian coastline has an exploitable capacity of 114 GW, divided between wave and tidal energy, and this potential is considered to be of great importance for supporting global decarbonization efforts. This study aimed to identify and quantify the energy potential of suitable locations for installing wave energy farms equipped with the OWC onshore device. These locations were surveyed using QGIS software, resulting in a georeferenced map with a database of 319 sites. The survey revealed an exploitable capacity of 9.73 GW in ten of the seventeen coastal states, with an estimated energy output of 83.7 GWh per year, equivalent to two times the energy consumption of the State of Rio de Janeiro, which has a population of approximately 17.5 million. It is concluded that replacing the same amount of gas-fired thermal energy with wave energy would reduce CO2 emissions by about 44.52 million tons of greenhouse gases per year. This result suggests that wave power generation can be included in studies on the expansion of the Brazilian electricity system, acting as a catalyst in the energy transition.

In face of the necessity for the minimization of the environmental impacts in the power sector, of the low and slow pace of strategies formulation for Brazilian decarbonization, this work was placed and justified. The main goal resides in analyze CO2 Capture by Chemical Absorption as an available technological tool for decarbonization in the Brazilian Power Plants, especially, the National Coal-fired Power Plants. Thermodynamic, economic indicators, discussions over performance and costs trade-offs, decision-making, and the impacts of the Carbon, Capture, Utilization and Storage had on the Power Plants typical operation were applied as a methodology for holistic evaluation of such the proposition. The results pointed out that independent of the capture index, post-combustion capture by chemical absorption is unviable due to economic performance. The retrofit cause to the Power Plants efficiency decay between 9% and 40%, and from 14% to 61% energy penalty. The energy penalty was reflected in economic penalty, leading the electricity production cost from 37 to 118 USD/MWh, when Future Scenarios were addressed. Therefore, it was concluded that further action must be taken to decrease energy demand in CO2 capture in order to reach economic competitiveness with chemical absorption. Moreover, the use of Piperazine was economic favorable due to its properties that implied smaller piece of equipment, and also due to its better performance for higher capture rate indexes. Governmental action is expected, however, must be beyond simple subsidies, which were merely relevant for economic penalty. Furthermore, it is shown that the strategy of Carbon Capture systems for Brazil would avoid between 6% and 6,5% of emissions in the South Region. However, to take such undertaking, the equivalent of 58% of announce investment for decarbonization might be compromised.

Cemented carbides are formed by the association of very fine powdered particles of hard carbides with tough metals. They are generally composed by tungsten carbide, which provides high hardness and wear resistance, and cobalt, which increases the material's tenacity. Due to this good combination of properties, they can be applied in several engineering areas, such as machining, mining and construction industry, reducing costs and increasing the useful life of tools, when compared to conventional steel. Cobalt is the most used binder in cemented carbides due to its superiority in relation to other binders in several factors, such as: good wettability in WC, high solubility of WC in cobalt at the sintering temperature and, above all, the width of the carbon window. However, several researches have been carried out searching for alternative binders to cobalt, as the corrosion resistance of conventional tungsten carbide/cobalt cemented carbides is not satisfactory in certain applications, such as the chemical and food industries. Thus, this study compared the corrosion behavior of WC-NiSi, WC-NiAl cemented carbides with that of conventional cemented carbide WC-Co. Samples were characterized by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and Vickers microhardness tests. Microscopy of all the samples showed a typical carbide microstructure, with an appropriate distribution of the binder by the faceted WC grains and without the presence of the undesirable graphite and η phases. The addition of aluminum and silicon to the nickel binder considerably increased the cemented carbide hardness, with the silicon sample providing hardness values similar to cemented carbide WC-Co. All samples showed continuous decreases in weight loss rates during the immersion corrosion test period, with the WC-NiAl sample showing the best corrosion resistance in this test. In the electrochemical tests of open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy, the samples with nickel binder showed nobler potentials, decrease in current density values and a total impedance higher than the sample with cobalt. The WC-NiAl sample showed the best corrosion resistance, with the best response in both the immersion test and in the electrochemical tests.

This work presents an experimental and numerical procedure for estimating the thermal input in the capacitive discharge welding process of K-type thermocouples wire. The objective of the work is to promote improvements in a device at the important temperature, the thermocouple. The work of proposed improvement in the solution of this in metals and also of possible energy solution of risk solution. The thermal model used is based on the equation of transient three-dimensional heat diffusion with phase change, modeled as a function of enthalpy. The thermal properties of chromel and alumel, materials that make up the two wires of k-type thermocouples, were considered temperature-dependent. The model was solved using the program COMSOL Multiphysics. The equation of the power curve in relation to time was defined from theoretical concepts of capacitor discharge. The nonlinear inverse problem technique used to solve the heat conduction problem was the iterative Function Specification Method. This technique estimates the heat rate that minimizes an objective function, defined as the square of the experimental and numerical temperature difference for each time interval. A numerical code was used in MATLAB together with software COMSOL Multiphysics to applied the inverse problem technique. The experimental method was used to obtain temperatures close to the welding region, which were used to apply the inverse problem technique. To calculate the efficiency of the process, the integral of the power estimated by time was used, and the energy stored in the capacitors bank of the equipment, defined by concepts of electricity. The proposed methodology was able for estimating the thermal input and efficiency for the capacitive
discharge welding process.The heat rate was estimated from experimental temperature data, the temperatures calculated computationally, from the estimated heat rate, showed low divergence in relation to the experimental data. In addition, the development of a capacitive discharge welding equipment is presented. The equipment consists of a capacitors bank that stores the energy supplied by a switched source. The amount of energy stored
in capacitors bank is controlled by an Arduino microcontroller. The equipment interface has a liquid crystal display and a button, which allow the operator to select the type of thermocouple he wants to weld. This equipment was able to weld thermocouples wire thicker than 24 AWG.

Fault diagnosis is critical to any maintenance industry, as early fault detection can prevent catastrophic failures as well as a waste of time and money. In view of these objectives, vibration analysis in the frequency domain is a mature technique. Although well established, traditional methods involve a high cost of time and people to identify failures, causing machine learning methods to grow in recent years. The Machine learning (ML) methods can be divided into two large learning groups: supervised and unsupervised, with the main difference between them being whether the dataset is labeled or not. This study presents a total of four different methods for fault detection and diagnosis. The frequency analysis of the vibration signal was the first approach employed. This analysis was chosen to validate the future results of the ML methods. The Gaussian Mixture model (GMM) was employed for the unsupervised technique. A GMM is a probabilistic model in which all data points are assumed to be generated by a finite number of Gaussian distributions with unknown parameters. For supervised learning, the Convolution neural network (CNN) was used. CNNs are feedforward networks that were inspired by biological pattern recognition processes. All methods were tested through a series of experiments with real electric motors. Results showed that all methods can detect and classify the motors in several induced operation conditions: healthy, unbalanced, mechanical looseness, misalignment, bent shaft, broken bar, and bearing fault condition. Although all approaches are able to identify the fault, each technique has benefits and limitations that make them better for certain types of applications, therefore, a comparison is also made between the methods.

The use of clean and renewable sources is a practice that is gaining more and more space and visibility in the energy generation sector. Resources are spent on a daily basis in search of new technologies and new fuels that meet the requirements of reducing pollutant emissions, emission of carbon dioxide and a sustainable development policy. Among the solutions found, the use of biomass as energy sources and improved technologies for combustion, such as the Dual-Fuel technique, are options that promote decarbonization and a reduction in polluting gas emissions in general. In this context, the present work aimed at the experimental study of HVO as a renewable fuel to be applied in a single-cylinder internal combustion engine, neat or in Dual-Fuel combustion with hydrated ethanol, in a dynamometric bench, where performance parameters and emission of polluting gases were evaluated. With the experimental data added to inventory data collected from the literature on the production cycle of HVO from palm oil and soybean oil, a Life Cycle Assessment of the biofuel was carried out. The adopted methodology consisted of developing the test bench with all instrumentation, data analysis methods and calculation of measurement uncertainties, test planning aimed at the application of motor generators, and analysis of the parameters of interest. Tests were carried out using neat HVO compared to neat conventional diesel and tests using dual combustion of Diesel-Ethanol and HVO. For Life Cycle Assessment, the SimaPro 9 software and the ReCiPe 2016 Midpoint (E) calculation method were used. The results obtained with pure HVO showed reductions in specific levels of emissions of NOx, HC, CO and particulate matter (PM) of 30%, 75%, 81% and 55.3%, respectively. The reduction is mainly due to the physicochemical properties of the biofuel. The Dual-Fuel application provides a significant reduction in CO2, NOX and MP emissions. The life cycle analysis showed that the HVO produced from palm oil has an environmental performance superior to that of soy, with a reduction in the Global Warming Potential of up to 75% and impact categories such as Terrestrial Acidification, Ozone Formation and Consumption of Non-Resources renewables present lower levels when compared to diesel. The environmental impact of the 'Dual-Fuel' operation shows a decrease in the levels of Global Warming Potential, Depletion of Fossil Resources and Ozone Formation.

O estudo sobre o fresamento de topo do aço inoxidável duplex vem ganhando destaque, devido aos desafios encontrados em sua baixa usinabilidade. Isso ocorre, pois, esses materiais apresentam baixa condutividade térmica, alta tenacidade e alta taxa de encruamento. Entretanto, para garantir qualidade final em produtos manufaturados, é importante que o processo de fresamento seja bem planejado, visando menores desgastes nas fresas durante o processo e ao mesmo tempo apresentando bons indicadores de produtividade. Assim, este trabalho tem como objetivo realizar uma otimização robusta multiobjetivo no processo de fresamento de topo do aço inoxidável duplex UNS S32205. Foram realizados experimentos seguindo um planejamento composto central combinando as variáveis de controle: velocidade de corte, avanço por dente, profundidade de corte e largura fresada e as variáveis de ruído: desgaste de flanco (vb), vazão de fluido (Q) e o balanço da ferramenta (lt0). As variáveis de respostas avaliadas foram a rugosidade da peça usinada e a taxa de remoção de material. Foram aplicadas as metodologias de superfície de resposta, de projeto de parâmetro robusto, do erro quadrático médio e da interseção normal à fronteira. Em seguida, foram analisados e discutidos os efeitos das variáveis de controle e de ruído, bem como as interações destas sobre as características de interesse. O desgaste da ferramenta foi a variável que mais influenciou a rugosidade Ra. A taxa de remoção de material foi influenciada por todas as variáveis controláveis do processo. Os valores obtidos para a rugosidade Ra variaram entre 0,24 a 1,10 µm e a taxa de remoção de material variou entre 40,39 a 187,52 mm³/s. A otimização da média e da variância de cada característica de interesse foi realizada, bem como a otimização do erro quadrático médio. Assim, 21 soluções Pareto-ótimas foram obtidas, contribuindo para a melhoria da qualidade superficial e da produtividade no processo de fresamento. Nos ensaios de confirmação empregou-se um arranjo ortogonal de Taguchi (L9) onde obteve-se os setups ótimos capazes de mitigar a influência das variáveis de ruído, o que corroborou a boa adequação da metodologia proposta.

Population and urban growth in Brazil in recent decades have increased the national vehicular fleet, which, in general, uses fossil fuels whose burning results in pollutant emissions. Allied with economic factors, there is an urgent concern to replace these fuels with those from renewable sources. Much of the research in this area uses
experimental techniques, which are not always feasible. Thus, combining computational analysis with these techniques is of great relevance. In this context, this work analyzed computationally the combustion cycle of a Diesel engine operating with fossil diesel, HVO and HVO with biogas. For this purpose, its 3D combustion chamber geometry was modeled in a CAD software and the CFD simulations were carried on ANSYS/Forte software. A kinetic model with 35 species and 74 chemical reactions, together with the RANS RNG k-ε model, the KH-RT model, a uniform injection profile and experimental values for initial pressure and temperature were considered in the modeling step. In addition, a 0-D analysis in ANSYS/Chemkim-Pro software was
performed to estimate some parameters not measured experimentally, and also to obtain two adapted kinetics models to describe the of pure HVO and HVO-biogas blend, which was done together with a mono-objective optimization process by the Lichtenberg algorithm. Both 0-D and 3D approaches were validated with experimental data. From the simulations, in-cylinder pressure and its rise rate, rate of heat release,
and its accumulation, turbulence, and emissions characteristics were obtained as a function of crank angle. 3D fields of velocity, temperature, the spray of diesel, and molar fractions of CO, CO2, NO, and NO2 were also obtained. The in-cylinder pressure obtained computationally showed a good agreement with the experimental ones (which were obtained from the R&D project ROTA 2030 by GETEC-UNIFEI at 2021 and 2022), but with a longer ignition delay. It was observed that the in-cylinder pressure is strongly dependent on the duration of injection. It was also verified that the regions closer to the TDC presented the most variations in the analyzed parameters and with the maximum values. Besides, the combustion of HVO and HVO with Biogas reduced
the peaks of pressure and heat release, as well as NOx and soot emissions and also presented more significant homogeneity in the velocity and temperature fields.

The Brazilian industrial sector has suffered great losses due to abrasive wear, since this type of wear is one of the main factors for machinery and equipment breakdown. In order to mitigate this problem, cemented carbides have been increasingly used in applications involving abrasive wear.
Conventional carbide is a cobalt and WC material, which has certain disadvantages, one of the main ones being the low corrosion resistance due to the cobalt binder. Thus, research conducted by Penrice (1987), Almond and Roebuck (1988), Tracey (1992), point to nickel as more promising and lower cost.
The nickel binder is a less expensive material, has superior performance regarding oxidation and corrosion in acidic and aqueous environments compared to cobalt, but loses in wear resistance by presenting lower hardness. Thus, the combination with auxiliary carbides arises to increase the hardness of the composite.
An important factor regarding the manufacture of carbide, which is by powder metallurgy, is the fact, that the composite produced presents a certain level of porosity. This porosity is responsible for performance losses to abrasive wear. Thus a good final product should have a low level of porosity.
The evaluation of abrasive wear consisteddistância in subjecting three specimens with distinct nickel binder and auxiliary carbides and one with cobalt binder to a microabrasive test, monitoring the wear evolution, the acting micromechanisms, and later comparing the results between both specimens.
Scanning electron microscopy was used to evaluate the worn surface and study the actuating wear mechanisms, where it was possible to observe the action of the two-body and three-body mechanisms.
In the wear test, compared to the samples with the conventional carbide 90WC-10Co, sample 90WC-9.5Ni-0.5Al performed better, sample 90WC-8Ni-2Mo2C performed similar wear behavior, and finally sample 90WC-8Ni-2Cr3C2 showed the lowest performance.
Given the results it is possible to say that cemented carbides produced with nickel and added carbides to improve performance are efficient since they maintain quality in manufacturing in relation to porosity and thus can be an excellent option to replace conventional cemented carbide.

Nodular cast iron is one of the most used ferrous materials by engineering currently, whether
as components for the automotive industry, for the basic sanitation industry or for the
component industries in general. One of the main raw materials for the production of cast iron
is steel scrap. Currently, this raw material is collected from different generating sources and is
composed of different types of steel with different chemical compositions. Many chemical
elements present in steel scrap, even in small percentage concentrations, are undesirable in the
production of cast iron, since some of them have the effect of causing significant changes in
their microstructure. The contribution of this study is to investigate the effect of the elements
copper, nickel, molybdenum and chromium, commonly present in steel scrap, as a promoter of
the martensitic matrix in a nodular cast iron in the as casted state. Contents lower than 1%w
were used for each element investigated and the pieces were produced by centrifugation casting
process. By analyzing the scanning electron microscopy images and semiquantitative analysis
via Energy Dispersive Spectroscopy, it was observed that nickel and copper were uniformly
distributed in the matrix, while chromium and molybdenum formed carbides in the intercellular
contours. Among the four elements investigated, molybdenum proved to be a strong promoter
of martensite formation and the fractions of this phase increased with the increase in the amount
added of this element (35%, 40% and 50%). The results obtained indicate the probable path to
obtain the totally martensitic matrix in as casted state and the possibility of eliminating costs
related to production on an industrial scale, such as the austenitization heat treatment followed
by quenching, which has an estimated operating cost of 26173.35 USD per month. It is
noteworthy that the analysis of the feasibility of eliminating the heat treatment should consider
the cost with the consumption of the ferro-molybdenum alloy and the particularities of the
process of each foundry.

In several regions of the world and diferente countries there is a transition of the electricity matrix in progress, driven mainly by environmental issues. However, there are geopolitical aspects involved, suah as the interests of countries with a strong presence of coal in their energy matrix. In this context, natural gas appears as a fuel for this energy transition. This perspective follows the increase in investments in infrastructure of the natural gas market and the fact that, among fossil fuels, natural gas is the fuel with the lowest greenhouse gas emissions. In addition, natural gas thermal power plants are interesting for the complementarity and reliability of the system and energy security. In addition, natural gas power plants are interestinh fot the complementarity and reliability of the system and energy security. Therefore, the presente work aimed to carry out a comparative analysis of four termal power Generation systems, being three coal-fired power plants (subcritical, supercritical and ultrasupercritical) and a combined cycle plant with natural gas, from the exergetic point of view, emissions of CO2 and annualized eletricity cost. Based on this comparison, a discussion was held about under what conditions the use of natural gas can have its use expanded in the contexto of the energy transition. It has been demonstrated that a combined cycle plant powered by natural gas with 57.95 % exergetic efficiency has an emission factor 60 % lower than that of a subcritical coal plant and avoids about 3.5 Mt of annual CO2 emissions. An economic analysis was also carried out and it was determined that the volatility of fuel prices has a strong influence on the cost of electricity. According to market conditions, supply and demand, the combined cycle plants presented competitive costs.

The present investigation aims to determine the technical and economic potentials of electricity generation from different types of biomasses in the state of Minas Gerais, using different electricity generation technologies, supported by different thermochemical combustion and gasification routes. The five most available biomasses in the state of Minas Gerais were selected: corn, soybeans, coffee, eucalyptus and sugar cane, whose crops produce residues that can be used for electricity generation. Considering the technical, logistical and economic data of the selected biomasses, the research sought to define the most viable types of residual biomass for electricity generation, in different locations within the state, through a multi-criteria decision-making approach (MCDM). A bibliographic review of the maturity of different types of electricity generation technologies from biomass was carried out, based on available information, schemes and operational parameters of real installations. The level of technological readiness of the different alternatives was also evaluated through a survey with specialists in the sector, concluding that the technologies with the highest level of readiness are the conventional Rankine cycle, the organic Rankine cycle and the use of gasifiers integrated with internal combustion. These three technological alternatives were adopted as options for the generation of electricity from biomass, obtaining a scale of the types of biomasses available, through a multicriteria methodology. The determination of the criteria weight was carried out from an integration with the analytical hierarchy process (AHP). In conjunction with a GIS-MCDA approach, different micro-regions were evaluated considering their respective biomass resources, allowing the estimation of costs and performance of different electricity production technologies. A logical algorithm was developed for the selection of alternatives for energy production from biomass, giving priority to technical feasibility, and considering factors such as the availability of biomass and its characteristics such as calorific value, humidity and granulometry. Investment costs, operating costs, as well as logistical costs for generating electricity from the plant, according to the technology used, were surveyed. Typical energy efficiencies for these cycles are between 8 and 30%, with conversion efficiency increasing with generation scale. To be analyzed, the generation systems were divided according to their power ranges in industrial application through power curves, in which plants with power above 5 MWe were to use the conventional Rankine cycle, power between 0.5 and 4.1 MWe using organic Rankine cycles, and the lower capacity potentials adopting the gasification and syngas burning cycles in internal combustion engines. It was found that eucalyptus prevailed as the most suitable biomass for most of the cases analyzed, due to its high energy power, followed by sugarcane residues, which are produced in greater quantities in the state. The conventional Rankine cycle was identified as the most mature technology and also had the lowest generation costs. In the projects that showed economic viability, the generation costs were between US$ 0.10/kWh and US$ 0.24/kWh.

Since CFD simulations for external flow problems may cause high computational costs, the present work presents a viscous/inviscid interaction method that allows to simulate the viscous flow in a reduced computational domain, which encompasses the rotational flow region (also called viscous subdomain). To this end, an interactive methodology is proposed, which consists of: calculate the potential flow outside the rotational region, impose the velocity of potential flow as a boundary condition at the boundary of the viscous subdomain, calculate the transpiration velocity to correct the potential flow, recalculate the field of potential flow velocities outside the rotational region, and update boundary conditions in the viscous subdomain. To determine the transpiration velocity, the velocity decomposition approach was used, which has been explored to develop methods of viscous/inviscid interaction. In this approach, to calculate the transpiration, it is necessary to first determine a boundary where the vorticity is negligible (called the rotational boundary). Determining the rotational boundary can be a complex task. Thus, two proposals were made to address this issue: the use of an auxiliary surface to facilitate the determination of rotational boundary (and to serve as a control surface for the potential flow), and to use of alternative criteria to evaluate the negligible vorticity. Calculations were performed in the viscous subdomain for two-dimensional, incompressible, steady, laminar or turbulent flows problems, on the profile NACA 0012 , bluff bodies and multiple bodies. The use of the proposed methodology allowed to reduce the computational costs, and the results of the aerodynamic coefficients and of the viscous flow fields obtained in the reduced domain, in general, were satisfactory for the engineering levels.

The study and analysis of the sound generated by flows has become increasingly important in several areas of the industry, from household appliances to aeronautical propulsion systems. A particular case is the noise generated by axial fans applied to the cooling systems in the generator sets. These equipment represent considerable noise sources that must be treated so as not to exceed the permissible limits. In this sense, several studies have been carried out with the aim of analyzing and proposing noise control techniques caused by the fan flow.
Therefore, aeroacoustics has become an important topic to be considered for the study and identification of noise sources and for the analysis of noise reduction techniques generated by rotor flow that can be incorporated from the design stage.
This work presents a methodology for the aeroacoustic design of axial flow fan rotors, considering the lift wing theory, the radial equilibrium condition, the free and non-free vortex condition and the incorporation of the sweep effect based on a cubic function, as an aerodynamic noise control technique. The analysis methodology used is based on the integration of Computational Fluid Dynamics techniques and noise prediction models to determine the main performance characteristics of fans and to evaluate the influence of the incorporated geometric variations (sweep) in the acoustic and aerodynamic fields of the fan.
Numerical analyzes were performed based on steady-state simulations to obtain fan characteristic curves and identify local noise sources. In a second approach, in transient regime, the sound pressure level was analyzed as a function of frequency for the analysis of the aeroacoustic behavior considering the ISO 13347-3: 2004 standard for the positioning of the receivers. The simulation methodology to obtain the aerodynamic magnitudes was validated through the experimental tests of a fan with constant thickness blades without torsion.
The experiments were carried out in the test bench suitable for ASHRAE (Norma 5175) / AMCA (Norma 210-74) standards of the Ventilator Laboratory (LabVent) of IEM/UNIFEI.
The main contribution of the methodology proposed in this work is the incorporation of aerodynamic noise control mechanisms from the design stage through an approach with low computational cost that consists of a sensitivity analysis to determine the parameters that allow reducing the local sources of aerodynamic noise without compromising the aerodynamic performance characteristics.
The results showed that designs incorporating sweep based on free vortex and forced vortex condition reduce noise sources and improve the aerodynamic performance of the fan compared to the base rotor geometry. It is important to highlight that the designed axial fan rotors present a consistent aerodynamic behavior in terms of hydraulic efficiency and total pressure, since the maximum efficiency values are far from the stall region.

Welding processes may cause undesirable residual stresses and their detection is possible using different methods. Some residual stress detection methods or techniques are destructive or semi-destructive, therefore not always applicable. Some methods are non-destructive, such as X-ray diffraction, neutron diffraction, and ultrasound. However, they are complex and high cost. One possible non-destructive method to detect welding residual stresses, lower cost than the current techniques, is being studied by some researchers. This method is based in the phenomenon which a structure natural frequencies vary when welding residual stress is applied. It consists in measuring the structure natural frequencies after welding, and comparing them to natural frequency values considered ideal values. These ideal values are obtained from finite element method simulation. However, the welding process simulation is not trivial; it implies at least four finite element analysis which can be executed in different manners. Different researchers have been developing studies with different types of structures, materials and results. The aim of this study is to analyze which parameters can improve Finite Element Method (FEM) model performance for obtaining simulation results closer to experiments. In this study, five models were developed and validated with experimental studies. It was observed that models using 2D shell elements generate better results than odels using 3D solid elements. In addition, it was observed that the symmetry technique which can be used in plate simulations leads to significant lower computational times, but affect modal results and, in addition, do not generate natural frequency values for all vibrational modes; therefore, the symmetry technique should be avoided in this type of analysis. The birth and death technique, which simulates filler metal deposition, was also analyzed and it was concluded that this technique has small effect in the results. Finally, this work proposes an interpolation technique for the natural frequency values to evaluate the modal results variation due to welding residual stresses.

This thesis addresses studies carried out in order to integrate the adaptive control techniques and the Universal Integral Regulator (UIR). The studies started with the implementation of a non-constant gain, but based on the error. This controller was called MUIR (Modified Universal Integral Regulator). This will be the first step towards implementing adaptive gains. Simulations with flight control of a quadrotor were performed. In order to validate the proposed technique, comparisons were made with the UIR, MRAC (Model Reference Adaptive Control) techniques and combinations of these techniques were tested. Comparisons were based on the results plotted on graphs and on the calculation of two performance indices: the accumulated error (AE) and the control demand (CD). An analytical stability demonstration of the MUIR control technique was also presented. After that, ways of integrating adaptive control with UIR were analyzed, and the obtained ways were tested. The contributions of this work were the presentation and detailed study of the MUIR controller applied to a quadrotor, and the initial studies carried out in order to design a Universal Integral Regulator with adaptive gains (AUIR).

Vanadis 8 tool steel is a material manufactured by powder metallurgy, widely used in the manufacture of dies, punches, tools for cutting and cold forming. This high-performance steel has a high carbon content in its chemical composition combined with the alloy elements Chromium, Molybdenum and Vanadium, with mechanical properties of high wear resistance, high tenacity, excellent dimensional stability, being applied in tools that require high durability. Furthermore, Vanadis 8 has high value-added , and when this material is machined, the process generates chips that are sold as scrap to companies that use remelting in their processes, an expensive technique that degrades the environment environment. Thus, this study aims to reuse Vanadis 8, using the powder metallurgy route. For this, it was realized the obtaining of the powders by the High Energy Milling in two phases. In the first phase of HEM, carbides of (Vanadium VC and Molybdenum Mo2C) were added during the milling process with a concentration of 3 %, in order to improve the mechanical properties. The parameters used were rotation 350 rpm, mass / ball ratio (1:15) and milling time 4, 8 and 12 hours.
In order to technically determine the most efficient configuration, analyzes were made such as: MO, SEM, DRX, Laser Diffraction, average crystallite size and degree of crystallinity. In the second phase of HEM, the factorial DOE and the DOE RSM were used to define the most significant parameters and to equate the model obtained by the responses of the laser diffraction and screening experiments. The parameter ranges in the second phase of the HEM were rotation 300–400 rpm, mass / ball ratio (1:15) and grinding time 12–50 hours. The analysis of variance (ANOVA) of the experiments, showed that for the laser diffraction the adjustments for the answers were inconclusive, due to the low value of R2 ad j. For the sieving experiment the adjustment of the responses showed a modeling within the acceptable limits, in which it is possible to obtain its equation. Through the results it was possible to
conclude that the mixing of the powder of V 8 with the addition of 3%of VC was the most efficient configuration for the reduction of particles, and with DOE RSM, it was determined that rotation was the most significant parameter. In addition, it was possible to notice by the DOE RSM modeling, that the greater the rotation and the time, the smaller the particle size, being that in the rotation of 400 rpm and time of 50 hours of grinding, the process managed to transform 78 % of the powders in particles with the same characteristics as those sold commercially, while with 400 rpm and 28 hours of grinding the process managed to reach 60 % efficiency, this configuration being the most economically viable.

This work presents an optimization procedure through the variation of the sweep curve of a two bladed Horizontal Axis Wind Turbine, previously tested by the National Renewable Energy Laboratory (NREL).

The simulation was conducted using unstructured mesh on whole domain, steady state with multiple reference frames: a moving reference frame around the rotor, and a steady reference frame on the far field region. The turbulence model was the k-ω SST, the coupling algorithm was the SIMPLE, and the discretization scheme was the first order upwind for the moment. It was also conducted a grid indepence study and a validation with experimental data from NREL Phase VI, using the moment as the control variable, whereby it was concluded that the numerical method was validated for a range of wind speeds from 5 m/s to 16 m/s.
In addition, it has been also made an integration of processes of geometry generation, mesh generation and simulation, aiming to optimize the power coefficient of the blades, by means of introducing the sweep angle on the geometry of the blades. The parameters of sweep, such as radial position of sweep start, maximum displacement of the tip and the exponent of the curve, were chosen as the design variables, and varied during the optimization process through genetic algorithm, with the power coefficient being the objective function.

As a result of the optimization process, it was possible to obtain two optimized geometries for the blade, one with forward sweep with an increase of 4,49% on the power coefficient; and another one with backward sweep, which has resulted in an increase of 5,62% on power coefficient. Both cases were tested for a wind speed of 11 m/s, which was the speed with the highest moment within the stable range of operation. Furthermore, it was built a metamodel, aiming to fastly get a better optimum point. The optimization with metamodel has yielded a turbine with 5,93% more Cp in comparison with the baseline turbine. Moreover, both geometries yielded greater power coefficients for all wind speeds between 10 m/s and 15 m/s.

This work presents a methodology for the conceptual design of Pelton turbines, where
configurations or dimensions are determined as a function of the nominal load condition. To
determine the energy and hydraulic efficiency of the turbine, losses in terms of specific
energy are introduced, and leakage and mechanical losses are then considered. This
methodology allows obtaining the spatial coordinates that represent the concave surface of the
bucket. The preliminary results of the project are compared with a numerical model in
transient regime (CFD), procedures and methodologies for the simulation are presented in
details, such as the construction of the mesh in the non-inertial domain, represented by five
buckets and sliding mixing interfaces between the inertial and non-inertial domains. The
multiphase, VOF and turbulence k-ω / SST models were selected considering step time values
around 0.000185 s., in order to represent the instantaneous torque resulting from the
interaction between the buckets and the jet. Simulation results were extended to analysis of
hydraulic efficiency, at the design point and at part load

Two-phase flows are widely found in the most diverse practical applications, such as refrigeration systems, nuclear reactors, oil refineries, power generation units and many others. Among the equipment employing two-phase flows, microfluidic devices have been gaining more prominence lately. These devices have dimensions on the order of a few microns and are used in different branches of industry (pharmaceutical, electronics, cosmetics, medical, etc.). In this context, the importance of studying the characteristics of two-phase flows is highlighted, as well as the processes involved in them, such as the formation, breakup and coalescence of droplets/bubbles. This work aims to study the flow of a droplet in a two-dimensional microchannel with a T-shaped junction. The behavior of the droplet at the junction and the breakup or non-breakup regimes of the droplet are investigated, as well as the influence of parameters such as capillary number and droplet length on its flow. The study is conducted by means of numerical simulations performed in the commercial software COMSOL Multiphysics®, which uses the Finite Element Method to discretize the governing equations of a physical phenomenon. The Phase Field Method, available in COMSOL, is used to represent the interface between the continuous phase and the dispersed phase of the two-phase flow. In addition, local mesh refinement and adaptive mesh refinement techniques are applied in regions of greater interest in the domain, such as the walls and the interface between the fluids, in order to improve the accuracy of the numerical solution. Different cases were studied, each with a combination of capillary number and droplet length as it reaches the T-junction. Data such as the droplet breakup regime and the temporal evolution of the minimum thickness of the droplet neck at the junction were obtained. All results were compared with results present in the literature, in order to validate the methodology used. Finally, it was found that the numerical results obtained were in good agreement with the literature.

Minas Gerais is the biggest charcoal producer in Brazil. This production happens in carbonization kilns that emit waste gases to the atmosphere, wasting useful energy and causing an environmental impact. In this work, an evaluation of the electricity generation potential from the effluent gases of the charcoal production in Minas Gerais was carried out using different electricity conversion technologies. A survey of charcoal producers in the State and their production was conducted in order to calculate the energy potential available in 2020 with a projection until 2030. For the electricity generation studies, three technologies were considered, namely: The Steam Rankine Cycle (SRC), the Organic Rankine Cycle (ORC) and the Externally Fired Gas Turbine (EFGT). For each technology, the efficiencies were calculated and applied for each of the previously surveyed producers. Efficiencies ranged from 5% to 24% depending on the type of technology power, ranging from 100kW to 2000kW. Maps of the power generation potentials in Minas Gerais were created, showing a concentration in the North and Northeast regions of the state. The highest power generation potential for the state was 1348 GWh/year using the ORC cycle with regeneration, superheating and n-decane as the working fluid. An economic analysis was also made, taking into account auctions for the energy sale in the energy market, together with a sensitivity analysis for each variable considered: Power, energy sale price, minimum attractiveness rate of return, taxes, plant operation time, and capital expenditure. The results demonstrate that the current technical and economic scenarios are not favorable for the implementation of electricity generation plants based on waste heat recovery from gases in charcoal production plants in the State of Minas Gerais, making feasibility in plants smaller than 10 MW practically impossible over a 10-year horizon. All technologies had energy sales prices above 100 US$/MWh, which is higher than the average of the last 3 years. However, the technological development in the charcoal production kilns and electricity conversion technologies, combined with an economic incentive based on environmental benefits, may provide an improvement in this scenario in the future.

RIBEIRO, A. R. B. (2021),Vibration Analysis in Sandwich Structures with Composite
Materials and Viscoelastic Core Using the Differential Transform Method, 208pp. Doctoral
Thesis, Institute of Mechanical Engineering, Federal University of Itajubá.
In this thesis a dynamic analysis is made through the solution of the differential equation
of motion of a composite beam model composed of three layers, two with composite material
and one with a viscoelastic core. Initially, the differential equation that governs the free vibration movement is obtained through the composite beam theory applying Hamilton’s Principle.
This equation is solved using the Differential Transform Method. Modal parameters such as natural frequencies and vibration modes are obtained. We describe step by step the development of specimens made with fiberglass material and epoxy resin, where the viscoelastic layer is embedded together between the layers of the fiberglass mat in the vacuum infusion process known as VARTM. The damping factors for composite beams with viscoelastic core are determined, using the velocity response in time of the free vibration test, using for this the representation of a system with one degree of freedom. Finally, the numerical results obtained are compared with other authors, theoretical and experimental results, in order to analyze the effectiveness of the theoretical equation and the solution method used. A good agreement between theoretical and experimental results is observed.

Decarbonization of the electrical matrix is a key component of mitigation strategies for environmental impacts aimed at reducing levels of carbon dioxide concentration in the atmosphere. The energy transition from fossil sources to renewable sources is an adequate measure to manage the reduction of emissions resulting from the energy generation process, while promoting the socioeconomic development of the regions where this strategy is applied. The present study aims to assess the long-term changes in the environmental and economic performance of Brazil's electricity matrix, based on the government plan. In order to achieve this objective, prospective scenarios were defined: the reference scenario is based on the government's energy expansion plan for the 2030-2050 horizon, and three others were drawn up based on this. For these, it was considered that there would be no growth in fossil energy sources in the future, and their participation would be constant, according to the generation values for the year 2019. Thus, in the second scenario, it was considered that the possible growth of the fuel fossil would be replaced by the maximum penetration of biomass in the 2030-2050 government plan, as well as in the third scenario it was considered that this replacement was made by the maximum penetration of the wind source and finally, the fourth scenario was considered the maximum penetration of the source photovoltaic (PV). The increase in the fossil source would only happen if the amount of maximum renewable energy penetration was not sufficient to supply the future energy increment. In order to analyze the environmental performance of the analyzed scenarios, the Life Cycle Analysis methodology was used and for economic performance, the leveled cost of energy (LCOE). The results show that the best performance for the Global Warming Potential (GWP) was for the scenario of maximizing the wind source, with an average value of 0.121 kgCO2/kWh and the worst performance for the scenario of government energy expansion, with the average value of 0.167 kgCO2/kWh. The lowest average leveled cost of electricity was for the wind expansion scenario, with 0.0438 USD/kWh and the highest leveled cost of electricity was for the biomass expansion scenario, with 0.0476 USD/kWh. The results of this study can support the formulation of policies for the future planning of Brazilian bioenergy.

In aerospace industry, composite materials offer several advantages, such as high weight-to-strength ratio and corrosion resistance. Aerospace materials are costly and have high safety standards, frequently using non-destructive testing in order to evaluate the material without incurring in further damage. Acoustic emission is a non-destructive testing method, which allows the signal processing to evaluate material performance during mechanical tests for determining material defects, for example. This study focused in the machining process of composite plates, in terms of surface finishing evaluation with comprehension of process phenomenology using non-destructive testing. Manufacturing processes are complex, especially the machining of composite materials, due to their specific properties and characteristics. The detection and prediction of surface finishing and occurrence of defects during manufacturing using non-destructive techniques is industrially useful, in terms of increasing automated manufacturing systems to increase productivity and quality control. The aim of this study is to show the possibility of online monitoring of the cutting process and to understand mechanism behind variables of control, with comparisons of different milling parameters and focusing in their impacts in acoustic emission signals, infrared thermography and surface finishing. The results indicates the relationship between cutting process and acoustic emission signals, with a key differentiation of other studies because it shows the not only the capability of detecting anomalies during cutting process and to predict surface quality by acoustic emission signal analysis, but also that is possible to develop new methods of monitoring in real time machined surface of composite parts quality using acoustic emission signals.

This work numerically investigates new interference patterns on flows around two circular cylinders aligned in tandem at subcritical Reynolds number regime. The origin of these interference patterns is hitched to surface roughness effects; consequently, the interactions viscous wake-body and viscous wake-viscous wake establish new vorticity dynamics for the problem. Overall, the numerical results reveal the potentialities of the present numerical approach to capture drag reduction accompanied of base pressure increasing, intermittence of vortex shedding and wake destruction under certain interference patterns. There is a lack of data published in the literature discussing roughness interference on flows around cylindrical structures in cross flow, which motived the present study. The analysis of the main numerical results enables important conclusions and, mainly, contributes to science evolution. Two contributions of this work can be highlighted: (i) implementation of an in-house vortex code to include surface roughness effects from a two-dimensional Lagrangian vortex method with LES type turbulence modeling, and (ii) implementation and parallel programming of the vortex code using OpenMP with Fortran. The numerical results confirm that the present model of surface roughness effects is much more sensitive than a simple two dimensional turbulence modeling. However, the turbulence modeling provided earlier the development of the model of surface roughness effects utilized in the present study. The latter utilizes points set near every solid boundary combining the generation of vortex elements and instantaneous change in the vorticity field into the boundary layer by introducing momentum because of roughness protruding out of the surface.

Prosthetic tubes are generally tubular structures without joints or moving parts. In lower limb amputations replaces the tibia and fibula bones as support structure and load transfer during walking or running. Commonly, prosthetic tubes are manufactured using metal materials such as stainless steel, aluminum and titanium. The mass of these tubes is generally high compared to tubes made of carbon fiber reinforced polymer matrix composite. Therefore, the main objective of this work is to optimize a new tube concept, made of composite material, which makes use of lattice structure and internal layer. For the development of the work, a Response Surface Methodology (RSM) technique was used to define in what quantity, under what conditions and which data should be collected during a given experiment, seeking to satisfy two objectives: the highest possible statistical precision in the response and the lowest cost. After the initial RSM
analysis, finite element method was used for the structural calculations and tube validation for each condition of the experiment generated by RSM. With the results obtained, it was possible to find equations that governs the problem. Later, by obtaining as meta-model equations, it was possible to optimize the parameters of the equations that were translated as responses applied to a lattice structure tube by the particle swarm algorithm (PSO) and genetic algorithm (GA). These optimal configurations have been computationally analyzed and found to be viable for use. By optimizing the Tsai Wu coefficient, when the structure is subjected to compression, it was able to decrease it approximately 83 %. Optimizing the mass, it was possible to decrease it by 14 % and have a lower Tsai Wu coefficient 22 %. In multi-objective optimization, the compression Tsai Wu was reduced by 63 %. Therefore, the objective of obtaining an optimal configuration for a new concept of tube for prosthesis of lower limbs was reached.

With the increase in consumption of raw materials, energy and waste generation, recycling is necessary for environmental and industrial reasons. Thus, the high energy grinding process together with the powder metallurgy technique, provides the production of duplex stainless steel powders with the addition of carbides becomes a new method for chip recycling. The objective of this work was the production of UNS S31803 duplex steel powders using high energy grinding from the chip, with the addition of vanadium carbides as reinforcements. Vanadium carbide provided greater comminution power in the milling process, with an average particle size of 42.27 μm. The complete factorial design was used to obtain the best sintering conditions for duplex stainless steel, taking into account the three most important factors in sintering which are temperature, compaction pressure and time. Two levels were used for each factor; sintering temperature (1200, 1240 and 1280 ° C), uniaxial compaction pressure (700, 800 and 900 MPa), and sintering time (1, 1.5 and 2 hours). Particle size analysis, scanning electron microscopy and X-ray diffraction were used to measure particle size and characterize powders. Statistical data revealed that compaction temperature and pressure are the most influential terms in the sintering process. The highest density obtained was 82% and the hardness value obtained was 72% in relation to the sample as received. The sintered material presented the phases ferrite, austenite, in addition to the martensitic phase induced by the deformation. And from the analysis of the properties it was verified that this method is viable, becoming an alternative route for the reuse of chips of a stainless steel.

Combined cycle power plants are increasing their role in the electricity generation worldwide. These plants stand out for their higher efficiency, lower electricity production costs and relatively low greenhouse gas emissions. In Brazil, a country with mostly renewable energy generation, these plants have been increasing their participation in electricity production. It is noteworthy that combined cycle power plants can show off as an alternative to diversify the Brazilian energy matrix and increase the reliability of the system, preventing supply crisis just like happened in the past. In this context, this works performs an energetic, exergetic and exergoeconomic analysis of a combined cycle power plant, using a full-scope simulator, which digitally and faithfully reproduces the operation of the EDF Norte Fluminense Power Plant, located in Macaé-RJ. Briefly, the simulator presents an exact duplicate of the real power plant and its operation is identical to the operation of the EDF Norte Fluminense Power Plant.
The results show that the energy efficiency of the studied plant is equal to 51.47% and the exergetic efficiency is equal to 49.25%. In addition, it was found that the equipment parts that are responsible for the main irreversibilities are: combustion chamber, gas turbines and heat recovery steam generators. From the exergoeconomic analysis, it was found that the cost of electricity production, for the base case, was calculated to be 0.3891 R$/MWh, which is 10% lower than the CVU calculated by ANEEL for the studied power plant. Finally, it was found that a longer plant’s annual operation time imply in the reduction of the cost of electricity production, which may motivate the use of combined cycle power plants as base load power plants, reducing the hydroelectric power plants dependence and providing to the final consumer lower tariffs than those observed in conventional thermal power plant operation.

Brazil has been on the spotlight since it is a country investing more and more in terms of generating electric energy by renewable sources. Building a Hydroelectric Power Plants of small medium and big capacities using the water movements is one of the most effective way of generating clean electric power. Then, it is possible to estimate future and past electric generation gain and losses correlating both data from the water critical periods and power plant installations. This paper presents a study of the reduction of hydroelectric energy generation for some Hydropower Generating Plants, due to the aging of forced pipes lead by the increase of the roughness of these pipes. This reduction is calculated using physical data from the plant, when compared to a generation scenario within the critical hydrological period of the system. An increase of the load loss and consequent reduction of the system power capacity was calculated from the pipes roughness temporal and internal evolution. Then, this study shows the effects of the phenomenon described above in terms of system performance throughout the years.

This research has the goal of exploring the biojet fuel production, by different routes, in
biorefineries scenarios integrated with palm oil mills and biodiesel plants. The biorefineries
are separated into four case studies, which have extraction, transesterification and a secondgeneration
ethanol plant, besides the plants for biojet fuel production, via HEFA and ATJ.
Furthermore, each one of the biorefineries has a cogeneration plant that is responsible for
supplying all the processes with thermal and electric energy. The biorefineries are thermodynamically
evaluated by means of the First and Second Laws of Thermodynamics, also are evaluated
by an exergoeconomic and an exergoenvironmental approach, an economical evaluation, and a
life cycle analysis. The results of the thermodynamical analysis point towards the immature character
of the biojet fuel production chain, due to the irreversibilities on those processes, and as in
the ATJ process are founded the highest exergetic and monetary costs of production among the
biofuels. The surplus of electricity produced at the cogeneration station has higher exergetic and
monetary costs in all the biorefineries. The economic analysis showed that Case Study 2 is the
most economical attractive case because it takes the lowest initial investment. Environmentally
the results indicate that the biojet fuel production is an alternative that can mitigate the effects
of global warming when the HEFA route is considered. The diversification of the biorefineries’
products contribute to the finances of the plant, but technically the production chains are not
fully prepared, once the best energy and exergy efficiencies are found in Baseline Case.

The stall is a well-know aerodynamic effect that consists of a lift abrupt fall due to the flow detachment from the body. Several studies were made in an attempt to suppress this effect, both to avoid air accidents and to improve aircraft aerodynamics and efficiency. This work presents numerical studies of viscous and incompressible Newtonian fluid flow on a pitching NACA0012 airfoil to analyze the dynamic stall delay and suppression. The boundary layer detachment control methods studied were with the introduction of slats, air jets, and suction in the suction region of the airfoil. For these studies, the COMSOL Multiphysics simulation program was used with the k-ω turbulence model and all simulations were carried out at the Heat Transfer Laboratory (LabTC) of the Federal University of Itajubá. The first study to suppress the dynamic stall effect was made by introducing slats to the airfoil, generating a stall delay and reducing the drag peak by 15.52%. In the second study, the implementation of blowing jets was carried out in three leading-edge positions with speeds varying from one to four times the flow speed. All cases with inflated jets there was a delay in the dynamic stall and for the cases with positioning of 2,5%c and 5%c, where c is airfoil chord, using inflation speed four times the free-flow speed the stall was tottaly suppress. The third study was aimed at adding a suction point in the upper region of NACA0012 where suction did not inhibit the dynamic stall, but made it possible to delay this effect. Qualitative and quantitative analyzes of the results were carried out through the pressure and velocity fields and the aerodynamic coefficients to demonstrate the delay and suppression of the dynamic stall effect. A validation study of the methodology used was also carried out comparing the results obtained with numerical and experimental results from other authors to demonstrate the good reliability of the methodology.

The present work consists of the study of two phenomena involved in fluid-structure interaction analysis, that is, the ground effect and Vortex-Induced Vibrations (V.I.V.). The purely Lagrangian Discrete Vortex Method is used for the numerical solution of the forced oscillation problem on a circular cylinder immersed in a fluid flow, with the body having a degree of freedom to oscillate only in the in-line direction, that is, in the streamwise direction. Under these conditions, there is an intense interaction between fluid and structure, and complex phenomena that characterize V.I.V. studies are manifested, such as the appearance of different regimes of formation and structural vortex shedding, the competition between these regimes and the phenomenon of synchronous coupling, lock-on, or lock-in. For the study and accuracy of fluid dynamic loads in the situation of forced vibration, this work contributes to the theoretical development and numerical implementation in the calculation of inertial effects in the integral formulation of the specific stagnation enthalpy. Separately, investigations are carried out regarding the influence caused purely by the proximity of a flat surface to the cylinder immersed in a flow using a numerical artifice which decouples the boundary layer originated along the flat wall, which produces a similar effect to the situation where the ground moves at the same speed as the fluid. The occurrence of phenomena such as the change in the stagnation point and the separation points of the boundary layer on the stationary bluff body, significant variations in the loads and suppression of the vortex shedding regime when the distance between the ground and the cylinder is very small were verified. In the end, investigations were carried out where situations of ground and V.I.V. effects are simultaneously present, investigating the dominance of one phenomenon over the other in situations where the effects were adverse. All simulations are performed for a Reynolds number equal to hundred thousand. In general, the studies had excellent correspondence with the literature. However, a study involving a similar situation with the performance of the two interference effects is rarely found in the literature for comparison.

Development of equipment for obtaining circular samples (diameters of 4mm) in
Powder Metallurgy (PM) by Compaction by Electric Discharge (EDC) and Sintering by
Electric Discharge (EDS), capable of performing Hot Compaction (HP) and Electric
Current Plasma Sintering (SPS) with the union of the two process steps in a single
equipment without the need to demould the sample. Dimension high amperage and low
voltage transformers (HALV) and develop a mold (matrix and / or punches) using the
thermal energy generated by the Joule Effect (JE) from alternating electric current (AC)
as a source of heat without casting. Sample. The operating ranges are: temperature
(room at 400ºC), time of each electric discharge (0 to 16s), pressure (0 to 9GPa) and
actuator travel (0 to 150mm) all independent variables, simultaneous or instantaneous.
The final shape of the electrodes has commercial characteristics, adapted for molds of
parts with recesses and thicknesses of 20mm in a stationary matrix, of simple action,
uniaxial and free atmosphere with registration of parameters applicable to ceramic
powders, polymers, metals, oxides, silicates and their mixtures in any compositions.

This study is focused on the assessment of the mechanical performance and the failure mechanisms of composites based on a liquid thermoplastic resin under several loading conditions compared to epoxy-based composites. Composite laminates reinforced by carbon fibers were manufactured by VARTM (Vacuum-assisted resin transfer molding ). The composites were subjected to mode II loading conditions in order to verify its damage tolerance. In this case, the thermoplastic composites presented 40 % more resistance to interlaminar fracture in comparison to epoxy composites. These materials obtained superior performance in crack propagation resistance because it tends to absorb the energy associated with crack propagation in the form of plastic deformation in comparison to epoxy composites. Tensile strength and in-plane shear tests were also performed to evaluate both materials response in non-conditioned and conditioned samples. The thermoplastic composites presented 30 % more tensile resistance in comparison to epoxy composites. For conditioned specimens, this difference was 14%. These results were related to plasticization which tends to favor the polymer softening providing a greater matrix plastic deformation, promoting a ductile fracture of the composite. On the other hand, the in-plane shear properties were 30 % higher for the thermosetting laminates for both conditions. In this case, moisture may have favored the formation of surface cracks and weakened the fiber/matrix interfacial adhesion. Additional analysis based on the design of experiments has shown that the Elium® 150 resin significantly affects all responses and presented in fact a better behavior in comparison to epoxy resin. While the conditioning effects have featured a statistically noticeable contribution to the tensile strength, the presence of the moisture did not provide a significant enhancement to the in-plane shear strength. The analysis based on accelerated test methodology of Carbon Fiber/Elium® 150 composites shows that the high frequencies increase the glass transition (Tg) to higher values probably favored by polymer chains movement. The artificial neural network evidenced an excellent agreement between the trained and experimental values. The long-term life prediction using master curves confirms that this new material can be considered to acoustic or vibrational damping purposes, considering its use in temperatures below Tg.

The multi-objective optimization algorithms commonly used in real engineering designs are based on evolutionary strategies. These algorithms often require a large number of evaluations of the objective function to achieve a good approximation of the Pareto front. In the case in which these algorithms are used to solve a real engineering optimization problem, which usually has computationally expensive objective functions, the time required to achieve convergence can be some time unfeasible. In this sense, the focus of this research was to develop a multi-objective optimization algorithm, based on a metamodeling strategy, to improve the optimization processes in engineering problems. The algorithm was developed, based on metamodel construction using radial based functions, to approximate the computationally expensive functions. These metamodels are optimized in an iterative sampling process to obtain new points in the decision space, with which the next expensive function evaluations must be made. In addition to being able to apply to multi-objective problems, the results showed a very satisfactory performance of the developed algorithm when applied to the select test problems chosen herein and in three real engineering problems: optimized design of wind turbine blades, aerodynamic optimization of wing geometry, and optimized design of linear cascades of axial flow machines. In most cases, the number of evaluations of expensive functions used by the developed algorithm was at least 3 times less than the expensive function evaluation employed, during the direct application of the evolutionary multi-objective optimization algorithm to achieve convergence with similar average values of coverage and diversity metrics of Pareto front.

Currently combustion processes represent the largest amount of energy generated in the world, energy used to sustain the current lifestyle, therefore it is also an important source of pollutants that promote the main contemporary environmental problems. Over time, due to its importance, researches regarding the improvement of combustion processes have been conducted in a variety of fields, such as yield improvement and use of new types of fuels. Among the new technologies used, flameless combustion offers basically a good yield combined to low emission of NOx and CO, and it is researched widely with gaseous fuels. The use of liquid and solid fuels has still been explored in the last years in a limited form, comparing with gaseous fuels. In this thesis, a combustion chamber was designed and built operating in a flameless combustion regime using non-traditional liquid fuels (waste tire Pyrolitic Oil) and diesel, for this purpose an effervescent injector was designed to guarantee the atomization inside the chamber. A computational simulation model was created and validated using the commercial Fluent/ANSYS® Academic Student 2019 R2 software to numerically determine the conditions under which flameless combustion using S-10 diesel would take place. The simulation results were compared to experiments performed in flameless chambers of similar geometry observing the results of the temperatures and the internal recirculation patterns (current lines) of the burned gases. The best recirculation conditions and temperature homogeneity were obtained for coefficients of excess air (λ) higher than 1.2. From the results of the fluid dynamics simulation, an effervescent type injector and a small combustion chamber, designed to work with up to 20kW, were designed and built. This chamber was tested with S-10 Diesel and with mixtures of S-10 Diesel and TPO (tyre pyrolysis oil) in mixtures of: 98% S-10 Diesel & 2% TPO, 95% S-10 Diesel & 5% TPO and 90% S-10 Diesel & 10% TPO. The carried out tests resulted in obtaining the flameless combustion regime with the extinction of the traditional flame, besides homogenization of temperatures within the chamber and a drop in NOx gas emissions.

There are two groups of methods to control wake destructive behavior and vortex shedding behind bluff bodies. The first one is the active method, where an external source of energy is needed to control the flow. The second one is the passive method, which is characterized by the modification of the body's geometry. Thus, the combination of the surface roughness of a body (passive control) and the approximation of that body to a moving horizontal flat surface (active control) was recently classified as a “hybrid control technique of vortex shedding and suppression”, during the development of this Doctoral Thesis. However, it is reported in the literature that some restrictions imposed by the current roughness models need to be overcome. Furthermore, there are few results in the literature combining both effects of surface roughness and ground plane. And for certain flow conditions, the results of a third overlap, which would be the effect of structural vibration of the body induced by the vortex shedding, are very rare. Especially if high numbers of Reynolds of practical interest are considered. In this Doctoral Thesis, a new roughness model is designed and developed, which is integrated with the Discrete Vortex Method, which already has an adaptation with the inclusion of a Large Eddy Simulation turbulence model. With this contribution, simulations and investigations of the effect of the surface roughness of a two-dimensional circular cylinder in the control of vortex shedding of it are performed for flows in a wide range of high Reynolds numbers. Other flow configurations are also simulated to test the sensitivity of the computational method. Parallel programming in the OpenMP standard is implemented to reduce the final processing time. The new roughness model was successfully implemented and was named the Lagrangian Dynamic Roughness Model – MLDRVL. The vortex formation regimes downstream of the body and the reduction of the drag force were mapped in accordance with the physics of the problem. The drag crisis was captured and investigated for 8 different surfaces of the circular cylinder, including flows in the critical and supercritical regimes which have greater difficulty in being numerically simulated. In particular, the results for the drag coefficient show a good approximation to the values obtained experimentally. The developed method was able to capture, even, the so-called separation bubble, which is a phenomenon that is difficult to reproduce, both by numerical simulation and by experimental investigation. The surface roughness of the circular cylinder isolated from other solid boundaries was able to reduce the drag coefficient by up to 51.6% compared to a smooth surface under the same flow conditions. The application of the hybrid control technique of vortex shedding allowed the drag coefficient to be reduced by 45.4% for the stationary circular cylinder and 57.7% for the circular cylinder vibrating in-line with the incident flow. Finally, parallel programming allowed a significant reduction in the processing time of a typical simulation, around 67% on average.

The use of aluminum in the most varied industries areas is a trend, justified by the range of properties of his alloys, besides the relative ease of their conformation; among them is the aluminum-zinc alloy Al 7075-T6, that stands out for its combination of density with good hardness and resistance to corrosion. Made in principle for aeronautical use, that alloy has been used for various activities, from structurals to plastic injection molds. Therefore, it is justifiable that the machining processes of this alloy must be more studied and understood. In this context, this work proposes the study of the Al 7075-T6 alloy turning, through an analysis based on Design of Experiments of the explanatory variables Cutting Speed (Vc), Feed (f) and Depth of Cut (ap) on the responses Roughness average (Ra) and Vibration (Cutting and Feed Direction) using coated and uncoated carbide tools with the same geometry. The results show that the coated insert gave slightly inferior surface roughness values when compared to the values obtained with the uncoated insert. It was also observed a bigger tool wear of the coated insert, which could indicate reaction between the elements of the coating with the aluminum. Therefore, it was observed that the Feed rate had a statistical significance influence on the surface roughness, and it was a significant relationship between roughness and cutting direction vibration. Finally, it was verified that the vibration, although influenced by the three explanatory variables, is influenced by other factors not foreseen in the study.

In many applications is necessary to, in a controlled way, project the mechanical properties of the materials applied. Examples can be found in biomechanical applications (implants and prosthesis), where the variety of materials that can be used is limited. Additionally, this material behaves in a completely different way from the ones found in the body natural structure component material. Such differences end up inflicting pain, discomfort and even wearing the joints. In this way, the possibility of defining the mechanical properties of structures allows a better control of the last improving and increasing the variety of applications. Motivated by the architected materials evolution – Metamaterials – and by the evolution of the additive manufacture techniques, the present work developed truss like structures with controlled mechanical behavior. The metamaterials here developed are compound of a repetitive cubic cell with truss like elements spread across its interior. This work aims to optimize these cells internal configuration to achieve the desired Poisson coefficient, simulating a material continuum with different properties from the one which the truss structure is made of. A methodology to optimize the base cell, in order to achieve a specific Poisson Coefficient, was formulated with a genetic algorithm and the finite element method. The formulation used is written in function of the nodal position, realizing a geometric non-linear analysis. The results show that the methodology adopted allows to project, in a controlled way, the mechanical properties, specifically the Poisson coefficient, allowing to obtain architected materials to diverse applications.

The Dish-Stirling systems are commonly installed at open fields with high wind
availability, so these solar energy conversion systems are often exposed at strong winds (Sun
et al., 2014). The incident winds on solar dish concentrators at high speeds makes the energy
conversion system be turn off in order to avoid damage to the solar concentrator (Sun et al.,
2014). Therefore, wind availability establishes a limitation in the operating time of this solar
energy conversion system. However, the main limitation of Dish-Stirling systems, intrinsic on
all solar energy conversion systems, concerning at the operating time of these systems limited
at the daytime, therefore there is no conversion of energy at night.
The presented proposal consists at the integration of the wind energy conversion in Dish-
Stirling systems, creating a new concept of the hybrid system. The hybridization will allow
the increase in the operating time of Dish-Stirling systems for the night time, allowing the
electrical power generation during the twenty-four hours of the day.
The technical proposed of the dissertation consists in Dish-Stirling system hybridization
based on development of a new concept of dish concentrator, the hybrid dish concentrator.
The conception of the hybrid dish concentrator consists in a solar dish concentrator associated
at wind blades turbines in the same structure, making the conversion of solar energy and the
conversion of wind energy. Therefore, the hybrid dish concentrator design basically includes
its solar project and its wind project.
The solar project of the hybrid dish concentrator was developed by applying the
geometrical sizing and thermal design methodology of the Dish-Stirling systems proposed by
Castellanos et al. (2017) and Hafez et al. (2016). The wind project of the hybrid dish
concentrate was developed by applying the blade element momentum theory (BEM)
combined by the fan sizing methodologies, and the computational fluid dynamics (CFD).
The technical feasibility of the hybrid system was analyzed through a comparative study
between the annual electricity generation of its system and the annual electricity generation of
the suchlike Dish-Stirling system, both installed in the same localization.
The results of the comparative study shown that the hybrid system presents a small
increase at the annual electricity generation than the Dish-Stirling system, confirming the
technical feasibility of the proposed hybridization. The analysis established by the design
parameters shown that the optimization studies applied on the hybrid system would result in
relevant increase of the electric power generation.

The increase in the biodiesel production in Brazil and in the world is generating a glycerol oversupply, making its prices to plummet down. The growing quantities of this by-product, along with its decreasing economic value is making the energetic valorization of glycerol object of several studies, which can configure an option for supplying the energy demanded by the biodiesel industry through the so-called cogeneration technique. In this context, the viability of supplying both electricity and heat from glycerol in a biodiesel production facility was assessed. For this, a biodiesel facility previously simulated by Galarza (2017) was used to estimate the quantity of glycerol and the energy demand to be considered in the simulation of the glycerol combustion and steam reforming, both through Aspen HYSYSTM software. Afterwards, the potential for electricity generation by using of a solid oxide fuel cell was evaluated through mathematical modelling using MATLABTM software. Finally, an economical analysis was used in order to evaluate the viability of the proposed configuration in a real system. It was found that, although the solid oxide fuel cell has presented high potential for electricity generation from the reform gas, being able to generate the 5,8 kW of demanded electricity, the economic aspect still pose a major barrier to the implementation of similar systems in real applications. Both the hydrogen and electricity production costs remained above market values for all scenarios, as the electricity was generated at values higher than 0,40 USD/kWh while the average value in the market is 0,12 USD/kWh.
Keywords: biodiesel; glycerol; cogeneration; biohydrogen; fuel cells;

Hybrid solar-biofuel turbines are interesting from the economic and environmental point of view, thus many researches are being performed in the field, as well as implemented in industries over the last years. The aim of this dissertation is to assess the performance of a solar hybrid micro gas turbine operating either with ethanol or natural gas and solar energy, including the economic viability of its hybridization. The microturbine computationally simulated was the Capstone C30, which is a regenerative gas turbine engine that operates with natural gas in standard condition. To simulate specific operational conditions, it was used the software GateCycleTM 6.1.2, using ethanol and natural gas as fuel, simulating a solar energy receiver located either in the high pressure or in the low pressure lines. The results showed a significant reduction in fuel consumption as the solar receiver increases the air temperature, particularly when the receiver is located in the high-pressure line, directly affecting the cost of the energy generated. In the hybrid cycle, despite the higher power output using natural gas, the ratio fuel energy by net power is lower when using ethanol. The cost of electric energy generation without solar energy is more attractive for the fuel natural gas, but the ethanol microturbine is more attractive to solarization. The lowest payback time was 4.4 years, obtained for the hybrid solar-ethanol gas microturbine for the receiver placed in the high pressure line and the highest 14.3 years, obtained for the hybrid solar-natural gas microturbine for the receiver located in the low pressure line. The solarization of these two turbine represents a revenue of US$ 376 227 and US$ 39 221 in 20 years, respectively.

In order to reduce energy consumption, several technological innovations have been incorporated into the cement production process. As an example, we can show the following technologies that were used in this work five- and six-stage cyclone preheaters and the bypass system. The five- and six-stage cyclone preheaters allow you to make the most of the residual heat from the rotary kiln exhaust gases, resulting in a reduction in the specific heat consumption of the process. Another example is the bypass system, where the objective is to remove the chlorine and alkali content of the exhaust gases from the raw materials to avoid the formation of cyclone incrustations and the formation of cracks in the exhaust gas concrete. This paper presents an energetic and exergetic analysis of three different cement factories, besides evaluating the factors that lead to the formation and the gaseous emissions. Case Study 1 presents an oven clinker production system equipped with four-stage preheaters and a precalciner. This facility has a bypass system with a deviation of 100% of the total volume of furnace exhaust gas. Case study 2 refers to an installation with a five-stage preheater furnace and precalciner equipped with a bypass system that deviates 15% of the total exhaust gas volume from the furnace. In case study 3, the clinker production system is composed of an oven that has six-stage preheaters and precalciner. The results show that for the three case studies, the preheater / calciner is the main source of irreversibility, as expected. The overall exergetic efficiency obtained for case study 1 was 30.87%, for case study 2 it was 28.94% and for case study 3 32.09%. The CO2 emission from the raw material from case study plants 1 and 2 was higher than the emission from the raw material from case study 3. Therefore, there was a significant increase in the efficiency of the case study. 3, as well as a significant reduction in the environmental impact of CO2 emissions.

In this study, gasification of oil sludge (OS) from crude oil refinery process has been investigated. Gasification process was simulated by Aspen-Hysys® (v.8.6) tools to evaluate the possibilities of hydrogen-enriched syngas production and its potential use in thermochemical conversion process. Five cases of study were evaluated in order to valorize OS wastes from oil refining. These cases include hydrogen production from syngas reforming and its potential use in the diesel oil hydrodesulphurization process (Case 1), synthetic liquid fuels production (Case 2), power electric generation (Case 3), ammonia (Case 4) and methanol (Case 5) production. Simulation of OS gasification process was carried out considering a kinetic model for main chemical reaction rate, according to OS compounds. Air and superheated steam mixtures were used as gasifying agents and its influence over gasification temperature, gas yield, chemical composition and heating value of gas, ash specific production, hot and cold gasification efficiencies were evaluated. Results from simulation work showed that OS thermochemical conversion require an operational temperature of gasifier above 1300 °C in order to ensure high conversion (> 90%) of heavy hydrocarbons content in OS waste. Thermal energy requirement for gasification was estimated between 0,80 and 1,25 kWh/kg OS, considering equivalence ratio (ER) and steam/oil sludge (SOS) ratio between 0,25-0,37 and 0,20-1,50 kg steam/kg OS, respectively. Specific gas yield from OS gasification between 2,14 and 3,34 Nm3/kg OS is expected, with hydrogen molar composition of about 10-25,0 mol%, indicating that a specific hydrogen production in the range of 0,21-0,84 Nm3 H2/kg OS gasified could be obtained as syngas reforming is reformed. Furthermore, a lower heating value (LHV) of produced gas in the range of 7,0-11,1 MJ/Nm3 was achieved,  while  ash production ranged between 0,10 and 0,17 kg ash/kg OS. For Case 1, hydrogen potential production was found to be 1,87 Nm3/kg OS, indicating that 28% of total hydrogen required for diesel oil hydrodesulphurization process could be replaced by hydrogen from OS gasification. For Case 2 and Case 3, a specific production of synthetic liquid fuels and electricity index close to 0,48 L/kg OS and 1,54 kWh/kg OS were calculated, respectively. Likewise, for Case 4 and Case 5, simulation results showed a synthetic ammonia and methanol production of about 1,41 L NH3/kg OS and 1,61 L CH3OH/kg OS, respectively. Finally, the five cases analyzed in this work represent promising technological alternatives to treatment and environmental management of OS wastes from crude oil refinery and its energetic added value before final disposal.  
 

Knowledge about the weldability of ferritic stainless steels of great academic and industrial importance by the potential for increasing the applicability of this alloy in various industry branches. Although the nature of welding processes can interfere with the microstructure joining materials by the combination of simultaneous heat actuation and deformation both present in the RSW (Resistance Spot Welding) process alters the magnetic properties, residual stress and grain size of ferritic stainless steels. Changes in addition to low resistance to welding limit the field of application of this material. In addition the present interstitial elements contribute to decreased toughness and corrosion resistance. Depending on the end use the magnetization present in the metal also becomes a complicating factor. Thus this thesis aimed to quantify the influence of RSW welding on the magnetic microstructural and residual stress properties of AISI 444 ferric stainless steel. DOE (Design of Experiments) statistical methods were used as an analysis tool. The process variables chosen were the current the time the pressure and the downward slope of the welding current. The possibility of demagnetization of the welded spot during the welding process was evaluated. Starting from an optimized condition the welding tests were performed together with an inductive displacement sensor to quantify the welding deformation. Evidence has shown that RSW welding parameterization has a significant influence on grain size and this in turn may influence some of the material's magnetic and tensional properties. Minimization of magnetic changes can be achieved during the welding process.

Nuclear power is a source with firm power, high capacity factor, greenhouse gas emissions
similar to renewable plants, and its high implementation costs are compensated by low
generation and maintenance costs. As such plants have high power and operate for long periods
uninterruptedly, small fluctuations or malfunctioning of their equipment imply significant
energy losses. Therefore, efficient operation plant is important to ensure maximum energy
production. The use of monitoring and diagnostic techniques in nuclear power plants are
fundamental in this process, in order to locate points of unplanned energy losses, allowing to
understand its origin and seeking alternatives to mitigate or even eliminate these losses. This
work makes use of exergy to evaluate three nuclear power plants with PWR reactors seeking to
identify and quantify the equipment irreversibilities, when the plant operates in the design
condition and in Valve Wide Open (VWO) condition. The analyses of high and low pressure
turbines of nuclear power plants were evaluated according to ASME standards (ASME PTC 6,
ASME 6A and ASME 6S). The use of ASME standards allowed us to obtain for the lowpressure
turbine: corrected enthalpy in its exhaust, the steam expansion curve, its effectiveness
and the quantification of the extracted water. The results allow us to conclude that the variation
in mass flow in the nuclear power plant may contribute to increasing the irreversibility of some
equipment, but it may favour the reduction of others, according to the operating condition of
the secondary circuit. In general, it was observed that the equipment irreversibilities will follow
a tendency of growth, or reduction, according to the different operating conditions of the plant,
but this tendency of growth or reduction is not observed for the exergetic efficiencies of the
equipment, which presented very distinct results between the conditions and the analyzed in the
power plants. The analyses also allowed us to perceive that the low-pressure turbine in the
condition of wide open valves (VWO) has a higher irreversibility than the one for the design
condition, although its power gain is substantially higher, thus compensating the increase of its
irreversibility in this condition.

This work aimed to analyze the influence on the mechanical, rheological and durability properties of a Self Compacting Concrete - SCC that had different percentages of sand replaced by metal slag and the simultaneous use of marble powder residue as a filler. To this end, a SCC Mix Reference was developed to meet all parameters of the ABNT NBR 15823: 2017. This SCC-REF was changed with the inclusion of four increasing proportions of metal slag (MS) (25, 37.5, 50 and 75%), then these new concretes were tested, and its properties, both fresh and hardened, were compared. The elaboration of the mix control assumed the principle of particle packing and paste optimization. The SCC-REF had the factor water/cement a / c = 0.35, silica fume SF / cement = 0.06, superplasticized/cement SP / c = 0.008. A new sequence of mixing concrete components in the concrete mixer was adopted in this research, which proved to be very efficient. The paste and mortar tests of the SCC-REF demonstrated the characteristics of a high flowability and moderate viscosity. The SCC-REF achieved all parameters of a fresh and hardened self-compacting concrete where it presented excellent results for parameters such as strength and durability. For the production of the mixtures aces with metal chips, small corrections of SF / c and a / c were necessary in some substitutions. Every SCC -MS mix reached all parameters of a fresh state SCC, with the exception of the SCC -MS 75, which did not reach the parameters of the L box. Comparing the results of all concretes, it can be concluded that the replacement of sand by MS is very viable and with replacement up to 50% does not significantly change any of the properties registered by the SCC-REF in both fresh and hardened state. According to the ABNT NBR 8953:2015 all concretes have achieved resistance to a compressive that classify them as structural and high performance. The splitting tensile strength of every concrete is around 10% of its compressive strengths. The values of the module of elasticity decreased with the increment of the substitution. The SCC -MS 75 presented a module of elasticity 20% lower than the mix REF. The surface hardness of concrete grows up to 37.5 of substitution, above this value, it decreases, but maintains a value equivalent to the SCC -REF. The Absorption A% and void index Iv% of concretes increased with the enhance of the substitution, but their low values indicate a durable concrete. Only the SCC -CM 75 is classified as inefficient. All concretes presented low capillary absorption values. Every concrete presented electrical resistivity at 28 days between 100 and 200 Ω.m. Meaning low probability of corrosion. The SCC -CM75 had a high probability of corrosion.  
 

This work presents an optimization methodology to increase the hydraulic efficiency of a prototype of ultra-low head turbine through the geometric modification of the draft tube, with the objective of maximizing the pressure recovery coefficient, Cp. In a first approach, in the 2D meridional plane, curves were parameterized and the introduction of a hydrofoil in the draft tube. For calculating the flow, a commercial tool of Computational Fluid Dynamics - CFD (ANSYS Fluent®) was used, integrated with stochastic optimization algorithms MOSA (Multi-Objective Simulated Annealing), based on Simulated Annealing, through the population of combinations of 12 geometric variables carried out through a random design of experiments plan. The result obtained with the optimization was compared with other geometric configurations of the draft tube featuring a higher Cp value. Based on the 2D approach, the cases analyzed were extended to three-dimensional analyzes, with the objective of comparing quantitatively and qualitatively the results of the hydrodynamic behavior in the draft tube. Finally, a comparative analysis by CFD between the turbine composed by the original draft tube and the turbine with optimized draft tube was performed, proving an increase in the hydraulic efficiency of the turbine from 82% to 84%. The applied methodology was satisfactory considering the optimization of the draft tube geometry, which represented an increase in the hydraulic efficiency of the turbine. This 2D-3D analysis methodology has the advantage of low computational cost in the integration of CFD and optimization algorithms, even with a considerable number of design variables.