Teses em Engenharia de Recursos Naturais da Amazônia (Doutorado) - PRODERNA/ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/4045

O Doutorado Acadêmico inicou-se em 2006 e pertence ao Programa de Pós-Graduação em Engenharia de Recursos Naturais da Amazônia (PRODERNA) do Instituto de Tecnologia da UFPA (ITEC) da Universidade Federal do Pará (UFPA).

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Acesso aberto (Open Access)
Aço inoxidável nanoestruturado produzido via soldagem a arco elétrico.
(Universidade Federal do Pará, 2021-07-08) LOAYZA, Cristhian Ricardo; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
Manufacturing methods of nanostructured stainless-steel composites (NSSC) have not yet been developed with industrial applicability. To overcome this shortage, the possibility of incorporating nanoparticles by electric arc welding was investigated, using a tubular rod filled with nanostructured flux composed of multi-walled carbon nanotubes (MWCNT) and 304L stainless steel particles. This flux was manufactured by two different methods: mechanical alloying (MA) and chemical treatment (CT) with hydrogen peroxide. The second showed more promising results using control of kinetic parameters of time and temperature, obtaining a lower degree of amorphous carbon, impurities, and crystalline defects, increasing their crystallinity and interaction of the nanotubes with the metallic matrix. MWCNT incorporation decreased the grain size by 64% when compared to the stainless-steel coating, possessing an austenitic matrix with carbide precipitation in the interdendritic spaces and grain boundaries. The microhardness increased 45% and the rate of erosion by vibratory cavitation decreased 64%, in relation to the AISI 304L coating. Additionally, XRD analyses showed a reduction of the γ{200} phase and a growth of γ{111} after the cavitation process. The method of manufacture of the nanocomposites proved to be economically viable and with the possibility of immediate application on a large scale.
Acesso aberto (Open Access)
Análise da transferência de calor convectiva por transformada integral em canais com paredes onduladas
(Universidade Federal do Pará, 2019-12-13) MIYAGAWA, Helder Kiyoshi; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785; https://orcid.org/0000-0001-9365-7498
The hybrid numerical-analytical approach known as the Generalized Integral Transformation Technique (GITT) is employed in the solution of the Navier-Stokes and energy equations that mathematically model the convective heat transfer in corrugated wall channels. The flow is considered laminar, incompressible, and two-dimensional involving a Newtonian fluid with temperature-independent physical properties, while wall temperatures are kept constant along the length of the channel. The streamfunction formulation is adopted, which eliminates the pressure field and automatically satisfies the continuity equation. Extensive convergence analyses are performed for the streamfunction and temperature fields, as well as for the product of friction factor by the Reynolds number and the local Nusselt number to demonstrate the robustness of the method. Verification of GITT results is also performed by comparing the centerline velocity, product of friction factor by the Reynolds number, average temperature, and local Nusselt number with those results obtained with the commercial COMSOL Multiphysics simulation software showing good agreement. The influence of parameters such as Reynolds number, wavy wall amplitude, number of waves, and phase between wall corrugations on the fields of velocity, temperature, and entropy generation are also analyzed, demonstrating their importance for convective heat transfer intensification and energy optimization.
Acesso aberto (Open Access)
Análise das distorções e tensões residuais em painéis enrijecidos soldados com FCAW robotizado e CW-FCAW
(Universidade Federal do Pará, 2022-04-22) RODRIGUES, Lino Alberto Soares; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
Once the influence of welding imperfections in the form of distortions and residual stresses on the resistance of stiffened panels has been proven, monitoring the levels of these imperfections becomes a safety criterion, in view of the uncertainty of the real resistance losses of the panel, without having to measure the magnitudes of these welding imperfections. Thus, this work deals with the measurement of distortion levels and residual stresses by X-ray diffraction and ultrasonic birefringence in stiffened panels. First, the best of three welding sequences were selected using robotic FCAW welding. Sequence 03 showed distortion levels up to 10 times less and a residual stress level closer to neutrality (±100 MPa) compared to sequences 01 and 02. Then, using sequence 03, panels were welded using the CW-FCAW process with 40% cold wire and welding speeds of 100 m/min and 120 m/min. The results showed that the percentage of cold wire with high welding speeds did not reduce distortions, but influenced the level of residual stresses, leading to stresses closer to the neutral line (±100 MPa) on average.
Acesso aberto (Open Access)
Análise de vibrações mecânicas em estruturas esbeltas e flexíveis, como cordas e vigas, sujeitas à movimentação axial utilizando a técnica da transformada integral generalizada
(Universidade Federal do Pará, 2024-05-28) PORFÍRIO, Rogilson Nazaré da Silva; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785; https://orcid.org/0000-0001-9365-7498
The dynamic analysis of vibrations on flexible structures is of an extreme importance in engineering and its solution represents a significant challenge to be tackled. This study has the objective to investigate thin and flexible structures such as beams and ropes, that oscillate in supports clamped-clamped and clamped-concentrated mass, which determine the boundary conditions of the analysis problem. Using the generalized integral transformation technique (GITT) that converts the partial differential equation (PDE) developed by the Hamiltonian method in an Ordinary Differential Equation (ODE), it optimizes the numerical process andcontrols efficiently the relative error of the calculations. In this study, it was developed and applied an innovative method that treats the boundary conditions without the use of filters to homogenize the equations. The calculations methodology was implemented in Fortran, utilizing a sub-routine DIVPAG of IMSL. As reference, a thorough analysis of convergence and stableness was applied, considering the behavior of four different models of ropes and two models of beams. The validation of methodology was approached comparing functional aspects such as transversal displacement, system velocities, frequencies, and damping, with results obtained by GITT and other studies that applied the same simulation conditions. The results of this study were found to be satisfactory, which highlights the relevancy of application of this vibration analysis method. It was also assessed the application of this method in different vibration configurations in each model, which exemplifies its broad potential in problems involving the structures analyzed. Therefore, this study represents a significant contribution to the advance of knowledge in dynamic modeling of thin and flexible structures and highlights the influence of boundary conditions in vibrational characteristics of these structures.Furthermore, it introduces an innovative methodology for treating boundary conditions without the use of filters, expanding the analysis possibilities in this field of engineering.
Acesso aberto (Open Access)
Análise do escoamento magnetohidrodinâmico micropolar de sangue e da captura magnética de nanopartículas em vasos sanguíneos
(Universidade Federal do Pará, 2025-05-09) PONTES, Fábio de Andrade; MIYAGAWA, Helder Kiyoshi; http://lattes.cnpq.br/5848592858919971; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
The aim of this work is to numerically analyze the transient two-dimensional magnetohydrodynamic pulsatile flow of micropolar blood considering the heat, mass and momentum transfers through a blood vessel in the presence of a magnetic field applied in the region of a symmetrical stenosis. The flow is considered laminar and incompressible and the magnetic nanoparticles are injected into the blood vessel and captured by the action of the magnetic field in the stenosis. The Method of Lines (MOL) was applied in the spatial discretization of the radial variable of the original 2D-transient model transforming it into a system of 1D-transient PDEs, which was solved numerically by the NDSolve subroutine of the Mathematica 13.1 software. The results of the converged MOL are verified with the results generated by the NDSolve subroutine applied directly to the original 2D-transient model and both are also compared with an analytical solution obtained for the limiting case, obtaining a good agreement between them. The effects of physical model parameters such as Lewis, Hartmann and Womersley numbers, the nanoparticle death kinetic constant and the mass Biot number are studied. The results show that in stenosis the flow is decelerated due to the magnetic field, as well as the microrotation velocity. The nanoparticle fraction field is also affected by the presence of the magnetic field, with concentration being increased in the stenosis region. The average velocity and microrotation increase in stenosis due to the narrowing of the arterial lumen. The average temperature and volumetric nanoparticles fraction are also elevated in the stenotic region due to the action of the magnetic field.
Acesso aberto (Open Access)
Análise energética, exergética e tecnoeconômica de um sistema de condicionamento de ar baseado na regulação natural da energia solar em condições climáticas da Amazônia
(Universidade Federal do Pará, 2023-09-01) SANTOS, Elson Costa dos; MACÊDO, Wilson Negrão; http://lattes.cnpq.br/3386249951714088
This work investigates the behavior of a photovoltaic air conditioning system, without batteries or connection to the electrical grid, operating according to the natural regulation of solar energy, in climatic conditions in the Amazon, a region with significant energy challenges, where in many locations, children, adolescents, adults and the elderly live without one of the main inputs for the development of productive, educational, leisure and even subsistence activities. The simulation results indicate that a system powered by a 1400 Wp photovoltaic generator can maintain thermal comfort conditions, with temperatures between 20 °C and 26 °C and relative humidity between 40% and 80%, for almost half of the operating time. and without any active control. Exergy analyses reveal variations in efficiency and irreversibility of components throughout the day, with the greatest impact on the photovoltaic system, followed by the compressor, condenser, evaporator, and expansion valve. Furthermore, the economic analysis shows that the implementation of these systems in parallel to systems powered by the conventional electrical grid can reduce grid energy consumption by 60.76%, and is strongly related to the tariff charged by the energy concessionaire. Finally, the research demonstrates the use of photovoltaic air conditioning systems as a sustainable solution for cooling, showing its effectiveness with the natural regulation of solar energy and its economic contribution to reducing the consumption of non-renewable energy
Acesso aberto (Open Access)
Análise quase-estacionária de pequena turbina eólica com pás curvadas
(Universidade Federal do Pará, 2023-10-20) VELOSO, Mauro José Guerreiro; CHAVES NETO, Antônio Maia de Jesus; http://lattes.cnpq.br/3507474637884699; VAZ, Jerson Rogério Pinheiro; http://lattes.cnpq.br/1623983294183975
The installed power generation capacity in renewable energy has stood out in Brazil lately. The Anuário Estatístico Energético Nacional 2023 reported that wind energy improved by 14.3% from 2021 to 2022. Despite the wind energy potential generation in Brazil, there are still obstacles to overcome, including challenges in research and development. So, researchers have conducted investigations on renewable energy, focusing on studying wind turbines' design and performance evaluation and other efforts to alleviate that task. Hence, research has not been conducted on the dynamic starting behavior of small wind turbines with different blade curvatures in wind power systems. In this sense, the main objective of this work is to analyze the influence of different angles of blade curvature on the dynamic response on starting the coupled turbine-generator set. Newton's second law, the blade element theory, and the extension of the Palmgren method are applied to obtain the wind turbine behavior at the start. The dynamic behavior measurements available in the literature at the start of the straight-blade wind turbine is been applied as a reference baseline to validate the methodology. Numerical simulations demonstrate that during start-up, turbines with straight blades and forward-swept blades start in less time, are approximately 19.9% faster at starting, and require 10.7% less wind speed than turbines with backward-swept blades. Compared to straight-blade turbines, backward-swept blade turbines increase the dissipative torque up to 5.86% and the dynamic efforts by 22%. These results indicate the significance of blade geometry on turbine performance and the existence of a swept angle at which the turbine performs better than other angles of the swept blade.
Acesso aberto (Open Access)
Aplicação de destilados provenientes do bio- óleo de pirólise de resíduos de gordura animal no asfalto diluído de petróleo
(Universidade Federal do Pará, 2024-08-12) VALENTE, Alex Lopes; MACHADO, Nélio Teixeira; http://lattes.cnpq.bhttp://lattes.cnpq.br/1500327307736428r/5698208558551065; https://orcid.org/0009-0002-4461-7611; BERNAR, Lucas Pinto
Waste animal fats (WAF) can be converted into distillate fractions similar to petroleum solvents and used as biofuels or in other applications through pyrolysis and fractional distillation. The distillate fractions from the pyrolysis of triglycerides exhibit adequate viscosity and volatility compared to petroleum-derived fuels but show acid values between 60-140 mg KOH/g, preventing their direct use as biofuels without considerable purification of the distilled fractions. Diluted petroleum asphalt (DPA), used for priming soil in the construction of flexible pavement, requires adequate viscosity, volatility, and penetration, and the distillate fractions from WAF pyrolysis oil can be used as partial or full substitutes for the standard solvent (kerosene) in DPA production. The aim of this study was to test the compliance of DPAs prepared by substituting kerosene with bio-oil fractions from WAF according to DPA standards. First, WAF is obtained from meat waste through the rendering process. Then, WAF is subjected to pyrolysis in a semi-batch fixed-bed reactor (2L), and the resulting bio-oil is fractionally distilled into gasoline, kerosene, and diesel fractions. The pyrolysis process is analyzed concerning the type of reactor used, with a focus on the influence of temperature and reaction time, as well as the distillation profile. The distilled fractions are characterized by density, viscosity, and acid value before being used in the preparation of DPAs by partial and/or total (0-40% by weight) substitution of standard kerosene. The mixtures were tested for kinematic and Saybolt-Furol viscosity, flash point, and penetration, according to road pavement standards. The results showed that the kerosene and diesel fractions from WAF can be adequately used in the preparation of DPAs as a total substitute for the petroleum kerosene typically used.
Acesso aberto (Open Access)
Caracterização de material compósito incorporado com fibras de bambu (Bambusa Vulgaris) e resíduos sólidos industriais para utilizacao como componente estrutural para a construcao civil
(Universidade Federal do Pará, 2020-03-12) SANTOS, Alessandro José Gomes dos; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
In the industry, the production of materials that bring less environmental impacts and that have high sustainability has been growing, mainly with regard to vegetable fibers and industrial waste. In this work, full isophthalic unsaturated polyester matrix, composites with bamboo vegetable fiber, composites with industrial residues (red mud, kaolin and copper) and hybrid composites with variation in the proportion of residues and fibers were made. The residues were used with granulometry of 100 MESH and the fibers in the lengths of 15mm and 30 mm, randomly arranged within the matrix. These fibers were used in natura and treated with 5% NaOH during the period of 2 (two) hours. The fibers were characterized in terms of their physical, mechanical and morphological properties. The composites were made by hand (hand lay-up) in the form of rectangular plates in metallic mold and pressed. The proportions of the mass fractions of the residues varied by 10%, 20%, 30% and 40%, whereas the mass fraction of fibers was varied by 1%, 2% and 3%. For the production of hybrid composites, the variation occurred up to the maximum saturation level of the matrix, with the proportion of residues / fibers of 10% / 3%, 20% / 3%, 30% / 3% and 40% / 3%, respectively. Bamboo fibers were chemically characterized by analyzing the levels of extractives, lignin and holocellulose. The residues were characterized mineralogically by means of X-Ray Diffraction (XRD). The composites were characterized physically (apparent porosity, water absorption and apparent specific mass), mechanically (traction, flexion and impact), flame retardancy and morphologically through Scanning Electron Microscopy (SEM) analysis. For physical characterization analyzes, 10 specimens (CP’s) were produced for each series. In the mechanical tests, 10 CP's were manufactured for the tensile tests, while for the flexion and impact tests, there were 8 CP's for each series. This same amount was used for the flame retardancy tests. After the physical tests, a small variation was observed with the addition of fibers and an increase in the Apparent Specific Mass with the addition of residues and fibers in the matrix. In the analysis by means of mechanical traction characterization, the best results of resistance limits in the values of 33.05 MPa were obtained for composites with 3% bamboo fibers treated with 15 mm in length and 33.11 MPa with bamboo fibers 30mm long without treatment. With the incorporation of waste, it reached a value of 40.25 MPa. In hybrid fractions the value reached 41.07 MPa with the addition of 20% kaolin residue / 3% bamboo fibers in the 15mm lengths with treatment. In flexion tests, the results were 150.94 MPa for the addition of treated 30mm fibers, 140.34 MPa for the addition of 20% kaolin residue and in the hybrids of 137.27 MPa for the addition of 30% kaolin residue / 3% bamboo fibers with 30mm treated. In the impact tests, the best results were 23.02 kJ / m² for the addition of 10% copper residue and 38.56 kJ / m² for the addition of 20% copper residue / 3% bamboo fibers with 30 mm long treated.
Acesso aberto (Open Access)
. Caracterização física, aspectos morfológicos, comportamentos térmico e mecânico do pecíolo do miriti como um material potencial para aplicações em pás de turbinas eólicas.
(Universidade Federal do Pará, 2024-10-28) GOMES, Igor dos Santos; VAZ, Jerson Rogério Pinheiro; http://lattes.cnpq.br/1623983294183975; WOOD, David Home
In many small wind turbine blades, the internal space between the laminated shells is filled with a core material. In this context, with the aim of enabling the application in both small and large blades, this thesis presents the petiole of the miriti palm (PMP) as a potential material for such applications. PMP is abundant in the Amazon region, and its harvesting does not harm the palm, as the petiole regrows, making the process fully sustainable. This could play an important role in enhancing the sustainability of wind turbine manufacturing. The physical properties, morphological aspects, and thermal and mechanical behaviors of PMP were determined and compared to balsa wood (BW). Additionally, the advantages of using the easily worked petiole for the core in manufacturing were considered, as demonstrated by the construction of a 0.598 m blade and starting performance tests of the turbine in both computational simulations and wind tunnel experiments. The results showed that PMP is about 50% less dense than BW. Consequently, turbine starting simulations indicated that the low density of the small blade made from PMP reduces starting time by 10% compared to EPS and by 42% compared to BW. While PMP and BW have similar morphological aspects as they are natural materials, BW tends to absorb about 3.6% more moisture and around 9% more water than PMP. The thermal behavior of PMP shows stability up to approximately 200°C, making it suitable for most wind turbine manufacturing processes. Regarding mechanical properties such as tensile, compression, bending, and shear strength, both BW and PMP exhibited elastoplastic behavior. Although BW generally possesses higher mechanical properties than PMP, the specific properties of PMP are greater than those of BW, except in cases where the load application does not align with the vascular bundle direction. For instance, the specific elastic strength and specific elastic modulus in tensile with a load applied at 90° in relation to the vascular bundle and in tensile with a load applied at 0° in relation to the vascular bundle of the PMP are approximately 13.5%, 3%, 30% and 61% higher than those of the BW, respectively. PMP’s specific elastic strength in GS compression is approximately 18.5% higher than BW. In shear strength, the specific elastic strength and specific modulus of elasticity of PMP are 20% and 54.5% higher compared to BW. Fatigue results indicate that PMP has a fatigue life of around 106 cycles. Wind tunnel tests showed that, regardless of wind speed, the best results for power coefficient, torque, and thrust were observed in 6-blade configurations, with values of 0.3083, 0.1224, and 2.2993 for λopt equal to 2.519. In analyzing the experimental results for rotation, thrust, torque, and kinetic energy ratio during turbine starting, the periods through which the turbine transitions between transient and steady states were observed, aligning with literature findings. The results presented in this work show that PMP has potential for application in wind turbine blades, as the combination of sustainable materials with significant specific mechanical properties, such as low density, has the potential to improve turbine design, reduce starting time, and extend the high-efficiency operating range.
Acesso aberto (Open Access)
Caracterização morfológica, cristalina e textural de bio-adsorventes produzidos via processamento hidrotérmico de resíduos de palha de milho com H2O sub-crítica: Aplicação na adsorção de ácido acético.
(Universidade Federal do Pará, 2021-12-06) COSTA, Maria Elizabeth Gemaque; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
This work aims to investigate the influence of temperature on the textural, morphological and crystalline characterization of bioabsorbents produced by hydrothermal processing of corn husk residues with hot compressed H2O. The experiments were carried out at 175, 200, 225 and 250 ºC, 240 minutes, heating rate of 2.0 ºC/min and biomass/H2O ratio of 1:10, using a pilot scale reactor of 18,927 L. The process is analyzed in terms of yields of reaction products as a function of temperature. The results showed yields of solids ranging from 62.92 to 35.82% (weight), gas yields ranging from 1.49 to 9.59% (weight) and liquid products ranging from 35.43 to 54.59% ( Weight). The yield of the solid phase decreases with temperature, presenting an inflection region between 200 and 225 °C, in which a drastic change occurs, while that of the liquid phase increases, presenting the same inflection region between 200 and 225 °C. The gas phase yield increases exponentially with temperature up to approximately 10% (weight) in the investigated temperature range. Elemental analysis of solid products shows that the carbon content increases, while the oxygen and hydrogen content decreases with temperature. The textural, morphological and crystalline characterization of solid phase products analyzed by TG/TDG, SEM/EDX, XRD and BET. The solid phase product (bio-adsorbent) obtained by hydrothermal processing of corn husk residues at 225 and 250 °C, 240 minutes, and biomass/H2O ratio of 1:10, were chemically activated with 2.0 NaOH solutions. M and 2.0 M HCl to investigate the adsorption of acetic acid solutions (1.0; 2.0; 3.0; and 4.0 mg/mL). The adsorption kinetics investigated at 30, 60, 120, 240, 480 and 960 seconds. The adsorption isotherm showed that chemically activated carbons were able to remove acetic acid from aqueous solutions.
Acesso aberto (Open Access)
Carbonização hidrotérmica dos caroços de açaí (Euterpe oleracea, mart) com H20 quente comprimida
(Universidade Federal do Pará, 2021-08-13) SILVA, Conceição de Maria Sales da; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
This work aims to investigate systematically the influence of process temperature, biomass-to-water ratio, and production scales (laboratory and pilot) on the chemical composition of aqueous and gaseous phases and mass production of chemical by hydrothermal processing of Açaí (Euterpe Oleraceae, Mart.) seeds. The hydrothermal carbonization carried out at 175, 200, 225, and 250 °C, 2 °C/min, biomass-to-water ratio of 1:10, and at 250 °C, 2 °C/min, and biomass-to-water ratios of 1:10, 1:15, and 1:20, in technical scale, as well as at 200, 225, and 250 °C, 2 °C/min, biomass-to-water ratio of 1:10, in laboratory scale. The elemental composition (C, H, N, S) of solid phase determined to compute the HHV. The chemical composition of aqueous phase determined by GC and HPLC and the volumetric composition of gaseous phase by using an infrared gas analyzer. For the experiments in pilot scale with constant biomass-to-water ratio of 1:10, the yields of solid, liquid, and gaseous phases varied between 53.39 and 37.01% (wt.), 46.61 and 59.19% (wt.), and 0.00 and 3.80% (wt.), respectively. The yield of solids shows a smooth exponential decay with temperature, while that of liquid and gaseous phases a smooth growth. By varying the biomass-to-water ratios, the yields of solid, liquid, and gaseous reaction products varied between 53.39 and 32.09% (wt.), 46.61 and 67.28% (wt.), and 0.00 and 0.634% (wt.), respectively. The yield of solids decreases exponentially with increasing waterto-biomass ratio and that of liquid phase increases in a sigmoid fashion. For constant biomass-to-water ratio, the concentrations of Furfural and HMF decrease drastically with increasing temperature, reaching a minimum at 250 °C, while that of phenols increases. In addition, the concentrations of CH3COOH and total carboxylic acids increase, reaching a maximum at 250 °C. For constant process temperature, the concentrations of aromatics vary smoothly with the temperature. The concentrations of furfural, HMF, and cathecol decrease with temperature, while that of phenols increases. The concentrations of CH3COOH and total carboxylic acids decrease exponentially with temperature. Finally, for the experiments with varying water-tobiomass ratios, the productions of chemicals (furfural, HMF, phenols, cathecol, and acetic acid) in the aqueous phase is highly dependent on the biomass-to-water ratio. For the experiments in laboratory scale with constant biomass-to-water ratio of 1:10, the yields of solid ranged between 55.9 and 51.1% (wt.), showing not only a linear decay with temperature, but also a lower degradation grade. The chemical composition of main organic compounds (furfural, HMF, phenols, cathecol, and acetic acid) dissolved in the aqueous phase in laboratory scale shows the same behavior of those in obtained in pilot scale.
Acesso aberto (Open Access)
Concentração e bioensaios alelopáticos e antifúngicos de princípios ativos da raiz de timbó via extração com CO2 supercrítico, extração com solventes e adsorção de soluções diluídas em leito fixo.
(Universidade Federal do Pará, 2014-12-18) ALMEIDA, Ossalin; ARAÚJO, Marilena Emmi; MACHADO, Nélio Teixeira
Acesso aberto (Open Access)
Controle de qualidade de bauxitas gibbsíticas: predição dos parâmetros AvAl2O3 e RxSiO2 a partir de dados difratométricos por reflexão e transmissão utilizando estatística multivariada
(Universidade Federal do Pará, 2021-02-16) MELO, Caio César Amorim de; PAZ, Simone Patrícia Aranha da; http://lattes.cnpq.br/5376678084716817; https://orcid.org/0000-0002-5880-7638
Currently, traditional wet chemistry methods are used for quality control of bauxites. Such methods indirectly quantify the gibbsite and kaolinite content as available alumina (AvAl2O3) and reactive silica (RxSiO2), respectively, and they are very costly and time-consuming. In order to achieve a rapid and reliable method to estimate these parameters, as alternative to current wet chemistry methods, in this work it is evaluated the use of multivariate statistics – Partial Least Square Regression (PLSR) on XRD data of Brazilian bauxites. The X-ray diffractograms were collected in the reflection and transmission modes, and the data collected by each of these treatments were compared with respect to the quality of the PLSR models. The method was optimized through Principal Component Analysis (PCA) and Factorial Design of Experiments (DOE), from which it was possible to identify outliers, grouping samples with mineralogical similarities into three clusters (C1, C2 and C3), and obtain optimized parameters for the collection and pre-treatment of diffractograms. The best results were obtained using the reflection mode, reducing the 2θ range to 13º – 34º 2θ, increasing the step size from 0.026º to 0.065º, and using standardized data. These collection conditions, although not ideal for most XRD applications, provided both a better accuracy of the predictive models of AvAl2O3 and RxSiO2 and a reduction in the collection time (~ 40 seconds). The results showed that the precision obtained was within the industrially acceptable limits for the quality control of gibbisitic bauxites (AvAl2O3 = 0.49% and 0.83%, and RxSiO2 = 0.32% and 0.23%, respectively for samples of the groups C1 and C2). The prediction was not satisfactory only for marginal bauxites samples (grouped mainly in C3). XRD by transmission allowed the elimination of the preferential orientation effect, however, the accuracy of the model was acceptable only for C1 samples. Compared to the traditional wet chemistry, the proposed method is significantly faster, easier to implement and perform the analyzes, requires less space and manpower, besides no chemical reagents are needed. In addition, with the implementation of X-ray diffraction in the laboratory of the bauxite and alumina industry, it is possible to follow the mineralogy of the ore that feeds the Bayer process and, therefore, to be aware of how variations in the mineralogical composition can impact the process. It is worth noting that such information is still unknown, controlling only the chemical parameters.
Acesso aberto (Open Access)
Custo de oportunidade (trade-off) para diferentes estratégias de manutenção de trilhos ferroviários na Amazônia
(Universidade Federal do Pará, 2022-12-22) CURCINO, Gabrielle dos Anjos; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
The emergency maintenance of railway assets in the Brazilian Amazon has generated revenue losses and opportunity costs. The general objective of this study was to identify the importance of opportunity cost in decision-making for corrective and preventive maintenance strategies. The methodology proposed the modeling of the variables referring to the economic and operational data of railway maintenance in the last ten years, by non-parametric Gradient Boosting Regression Tree machine learning, and hybridizing it with the analysis of the opportunity cost for the trade-off decision making of an ore railroad in the Brazilian Amazon. The results showed that the GBDT was efficient in fitting the training data with r2 equal to one. Similarly, the test data presented satisfactory r2 values, close to one, where the degree of importance of the independent variables in the prediction of the dependent variables was obtained. Pearson's method was used to construct the correlation matrix for each pair of variables. From the generated model, eight forecast groups were created for the year 2022. Then, conflict levels were established, suggested by the economic literature, between the forecast scenarios, where the opportunity cost was identified among the alternatives with the best benefit to maintenance strategies. In this way, the opportunity cost combined with machine learning serves as an instrument to help companies in the search for better maintenance decisions, which contributes to the improvement of rail asset management.
Acesso aberto (Open Access)
Descontaminação de máscaras N95 em hospital público de Belém/PA: apresentação e avaliação de protocolo simplificado
(Universidade Federal do Pará, 2024-11-25) MATTOS, Simone Lopes de; DIAS, Carmen Gilda Barroso Tavares; http://lattes.cnpq.br/2113791118142177
he author presents a protocol for decontamination of N95 filter masks by means of short wave ultraviolet irradiation (UV-C), as well as the results of the microbiological validation testing of the UV-C device and qualitative research on the adherence of professionals from the João de Barros Barreto University Hospital, of the University Hospital Complex of the Federal University of Pará (HUJBB) to the aforementioned protocol. The microbiological tests demonstrated the efficacy of the decontamination protocol, as there was no bacterial growth in culture media inoculated with swabs of masks used in the hospital and decontaminated in the UV-C device, which proved the germicidal efficiency of UV-C irradiation. The results of the qualitative research point to the adherence of nursing professionals to the practice of mask decontamination, recognizing the practicality and contribution of the protocol to biosafety and occupational safety. As part of the same protocol, an alternative packaging for storing masks in the intervals of use of N95 masks is presented, considering their safe reuse. The protocol also has the following advantages: low cost and practicality of use, in addition to contributing to the reduction of infectious waste. Descriptors: Decontamination. Ultraviolet Rays. Radiation Dosimeters. Personal Protective Equipment. Respiratory Protection Devices. biosecurity.he author presents a protocol for decontamination of N95 filter masks by means of short wave ultraviolet irradiation (UV-C), as well as the results of the microbiological validation testing of the UV-C device and qualitative research on the adherence of professionals from the João de Barros Barreto University Hospital, of the University Hospital Complex of the Federal University of Pará (HUJBB) to the aforementioned protocol. The microbiological tests demonstrated the efficacy of the decontamination protocol, as there was no bacterial growth in culture media inoculated with swabs of masks used in the hospital and decontaminated in the UV-C device, which proved the germicidal efficiency of UV-C irradiation. The results of the qualitative research point to the adherence of nursing professionals to the practice of mask decontamination, recognizing the practicality and contribution of the protocol to biosafety and occupational safety. As part of the same protocol, an alternative packaging for storing masks in the intervals of use of N95 masks is presented, considering their safe reuse. The protocol also has the following advantages: low cost and practicality of use, in addition to contributing to the reduction of infectious waste. Descriptors: Decontamination. Ultraviolet Rays. Radiation Dosimeters. Personal Protective Equipment. Respiratory Protection Devices. biosecurity.he author presents a protocol for decontamination of N95 filter masks by means of short wave ultraviolet irradiation (UV-C), as well as the results of the microbiological validation testing of the UV-C device and qualitative research on the adherence of professionals from the João de Barros Barreto University Hospital, of the University Hospital Complex of the Federal University of Pará (HUJBB) to the aforementioned protocol. The microbiological tests demonstrated the efficacy of the decontamination protocol, as there was no bacterial growth in culture media inoculated with swabs of masks used in the hospital and decontaminated in the UV-C device, which proved the germicidal efficiency of UV-C irradiation. The results of the qualitative research point to the adherence of nursing professionals to the practice of mask decontamination, recognizing the practicality and contribution of the protocol to biosafety and occupational safety. As part of the same protocol, an alternative packaging for storing masks in the intervals of use of N95 masks is presented, considering their safe reuse. The protocol also has the following advantages: low cost and practicality of use, in addition to contributing to the reduction of infectious waste. Descriptors: Decontamination. Ultraviolet Rays. Radiation Dosimeters. Personal Protective Equipment. Respiratory Protection Devices. biosecurity.he author presents a protocol for decontamination of N95 filter masks by means of short wave ultraviolet irradiation (UV-C), as well as the results of the microbiological validation testing of the UV-C device and qualitative research on the adherence of professionals from the João de Barros Barreto University Hospital, of the University Hospital Complex of the Federal University of Pará (HUJBB) to the aforementioned protocol. The microbiological tests demonstrated the efficacy of the decontamination protocol, as there was no bacterial growth in culture media inoculated with swabs of masks used in the hospital and decontaminated in the UV-C device, which proved the germicidal efficiency of UV-C irradiation. The results of the qualitative research point to the adherence of nursing professionals to the practice of mask decontamination, recognizing the practicality and contribution of the protocol to biosafety and occupational safety. As part of the same protocol, an alternative packaging for storing masks in the intervals of use of N95 masks is presented, considering their safe reuse. The protocol also has the following advantages: low cost and practicality of use, in addition to contributing to the reduction of infectious waste. Descriptors: Decontamination. Ultraviolet Rays. Radiation Dosimeters. Personal Protective Equipment. Respiratory Protection Devices. biosecurity.he author presents a protocol for decontamination of N95 filter masks by means of short wave ultraviolet irradiation (UV-C), as well as the results of the microbiological validation testing of the UV-C device and qualitative research on the adherence of professionals from the João de Barros Barreto University Hospital, of the University Hospital Complex of the Federal University of Pará (HUJBB) to the aforementioned protocol. The microbiological tests demonstrated the efficacy of the decontamination protocol, as there was no bacterial growth in culture media inoculated with swabs of masks used in the hospital and decontaminated in the UV-C device, which proved the germicidal efficiency of UV-C irradiation. The results of the qualitative research point to the adherence of nursing professionals to the practice of mask decontamination, recognizing the practicality and contribution of the protocol to biosafety and occupational safety. As part of the same protocol, an alternative packaging for storing masks in the intervals of use of N95 masks is presented, considering their safe reuse. The protocol also has the following advantages: low cost and practicality of use, in addition to contributing to the reduction of infectious waste.
Acesso aberto (Open Access)
Desenvolvimento de ligas de alumínio nanoestruturadas para a utilização em cabos elétricos
(Universidade Federal do Pará, 2023-03-15) PRAZERES, Emerson Rodrigues; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
Aluminum nanocomposites demonstrate the ability to improve mechanical properties, thermal and electrical conductivity. For aluminum, the incorporation of multi-walled carbon nanotubes (NTCPM) using conventional melting methods is an old problem, due to disintegration of the walls of carbon nanotubes when subjected to high temperatures. In this study, aluminum nanocomposites were manufactured by the conventional casting method, using stainless steel powder (304LSS), nanostructured silicon and nickel. The carbon nanotubes were treated with hydrogen peroxide, allowing adhesion by polar interaction with the particles of the metallic powders. The nanostructured compounds were added to the aluminum matrix by means of conventional casting. After obtaining the material as a melt, it went through the machining process to a diameter of 18.5 mm and then through the cold working process until a diameter of 3.0 mm was obtained. The alloys were characterized mechanically through tensile and microhardness tests, electrically through electrical resistance tests, using a 2-point kelvin bridge, and structurally through macrostructure and microstructure analyses. The 304LSS powder added alloying elements, refined the grains and the NTC improved electrical conductor performance, with electrical conductivity gains in the range of 10%. Associates associated with carbon-associated components not linked to chains of protein chains are compounds of carbon, associated with proteins, aggregates, associated with carbon, associated with proteins, associated with significant proteins in the LRT. The alloys with Ni and carbon nanotubes contributed to significant gains in electrical conductivity and LRT, with the alloy with 2% nickel and 0.1% NTC showing gains of approximately 8% in electrical and mechanical properties. Nanostructured alloys were also superior in terms of electrical and mechanical properties than commercial alloys.
Acesso aberto (Open Access)
Desenvolvimento de processo de zeólita A utilizando o caulim da Amazônia e aplicação na adsorção de Cu+2
(Universidade Federal do Pará, 2014-08-22) MORAES, Cristiane Gomes; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
Around the world millions of tons of inorganic waste are produced every day in mining and mineral processing. These wastes are stored in sedimentation basins or discarded in landfills, and very often are thrown directly into the environment without any treatment process. However, alternative recycling and/or reuse should be investigated and, where possible. This work shows studies in order to reuse the kaolin waste from Amazon, from a kaolin processing company for paper covering. For the synthesis of the zeolite in static and dynamic hydrothermal processes, was used as the silicon source and the aluminum kaolin waste, which passed through the calcination procedure in a muffle at 600°C to obtain metakaolin; and as sodium source chose to 5M sodium hydroxide solution. In the static method was used stainless steel autoclaves, in an oven at 110°C, using 1,75g of metakaolin, varying the time of synthesis and the mass of sodium hydroxide and the dynamic process, we used 100g of metakaolin, mass 34,5g sodium hydroxide; at 95°C under stirring system, varying the time of synthesis, in order to determine the optimal conditions in the synthesis of the zeolite in the process. Matches materials and zeolitic products obtained in the syntheses were characterized by: X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis and thermogravimetric (DTA/TG), X-ray fluorescence (XRF) and particle size analysis. There is the possibility of scale-up, since the zeolite obtained, the dynamic process in time of 30 min. Data from adsorption experiments determined by iodometric technique copper alloys and metal and minerals, adjusted by Langmuir and Freundlich suggest that the static and dynamic zeolitic materials have good adsorptive capacity reached 95% efficiency for concentrations in the range of 50 to 100mg/L, thereby demonstrating that these materials are efficient and cost effective alternative when used for the removal of heavy metals, in the case of copper, the treatment of industrial effluents.
Acesso aberto (Open Access)
Eletrodeposição e caracterização de revestimento de cobre/nanotubos de carbono dopados com iodo em fios de alumínio liga 1350
(Universidade Federal do Pará, 2023-09-19) RODRIGUES, Fabrício Augusto dos Santos; LEITE, Marcos Allan Reis; http://lattes.cnpq.br/8252507933374637
Nanocomposites based on copper and carbon nanotubes (Cu/NTC) in metallic matrix have been providing improvements in the electrical and thermal properties of materials, presenting great potential for application in areas such as the electrical sector. Great challenges are encountered in the transmission and distribution of electrical energy, such as technical losses, mainly due to the Joule effect, resulting in low efficiency of conventional aluminum (Al) conductors. In this sense, new nanostructured conductors were developed based on functionalized copper/carbon nanotubes and doped with iodine (Cu/NTC-f), as a coating for Al 1350 aluminum wires, using the electrophoretic deposition process in copper sulfate solution, under electrical currents of 1.2 A, 1.5 A and 1.8 A, were investigated for their electrical and mechanical properties. Al@Cu/NTC-f conductors were characterized by scanning electron microscopy; X-ray diffraction; Raman spectroscopy; tensile test, in addition to electrical measurements, at room temperature and under heating, via Kelvin bridge. The results show an increase of approximately 18% of the IACS with good stability under heating compared to the commercial aluminum conductor Al 1350, due to the intrinsic properties of the NTCs, functionalization, good dispersion and the doping effect of iodine, confirmed by Raman spectroscopy with redshifts in the Gint and Gext subbands. The characteristic morphology of the thin films of Cu/NTC-f, presented pyramidal structures, agglomerates, copper structures involved the NTC, as well as NTC homogeneously electrodeposited in the aluminum substrate with good crystallinity, cultivated in the directions (311) and Cu (220), Cu (200), favoring the formation of thin films with good crystallinity. This method of electrodeposition of Cu/NTC-f on the surface of metallic wires shows promise for the production of nanostructured metallic conductors of high ampacity, thermal stability, low density and high performance, applied in electric power transmission lines.
Acesso aberto (Open Access)
Estudo da influência da distribuição granulométrica dos finos de minério de ferro na liquefação durante o transporte marítimo
(Universidade Federal do Pará, 2022-05-06) MOREIRA, Debora Dias Costa; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
In recent decades, many incidents with bulk carriers have occurred due to the liquefaction of solid bulk cargoes, with iron ore being responsible for the largest volume of solid cargo business in the world. The liquefaction of solid bulk cargoes in bulk carriers has been one of the main causes of serious accidents, including loss of life and vessels. iron ore fines (IOF) are products prepared from the refining of iron ore and were reclassified, in 2011, by the International Maritime Organization (IMO), as a liquefiable material of the ' A group'. Currently, the transportable moisture limit (TML) is the only parameter used by the IMO to minimize the risk of liquefaction of 'Group A' cargoes for maritime transport. In this thesis, two methodologies were proposed to investigate the liquefaction potential of IOF, the first methodology aimed to classify the liquefaction potential of IOF samples considering the TML and the Coulomb cohesion factor and the second methodology aimed to use the table test of vibration for analysis of the liquefaction potential of the IOF through proposed indicators. The studies were performed with IOF samples prepared with particle sizes from 9.5 mm to 25 µm in different fines contents (particles < 150 µm) and moisture. In the first part of the thesis, the direct shear tests showed that the addition of fines content in the IOF samples provides great influence on the shear strength. It was also observed, through the Proctor/Fagerberg test and the flow table test, that the addition of fines content in the IOF samples produced an increase in TML. These results were used to propose a methodology for classifying the liquefaction potential of IOF. In the second part of the thesis, the modified Proctor/Fagerberg test showed that there is a transition fine content for the TML. Through the experimental methodology proposed for the vibration table test, it was observed that the liquefaction potential of the IOF has a correlation with the migration of moisture to the surface and values of void ratio, degree of saturation and density are equivalent to the methodology of modified Proctor/Fagerberg test compression. It ends with the proposition of the indicators, Ip and ISWC, which are useful parameters to evaluate the potential for liquefaction of IOF in samples with different contents of fines and moisture; for the tested IOF, Ip ≤ 3.63 indicated that there was no liquefaction and ISWC > 0 indicated liquefaction.