Programa de Pós-Graduação em Engenharia de Recursos Naturais da Amazônia - PRODERNA/ITEC

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/4044

O 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), em nível de Doutorado, tem como objetivos principais: formar quadros profissionais qualificados na área de Engenharia de Recursos Naturais; incentivar a pesquisa e o aprofundamento dos estudos técnicos e científicos relacionados ao uso e a transformação de recursos naturais; e contribuir para o desenvolvimento científico e tecnológico da região Norte.

Navegar

Agora exibindo 1 - 20 de 54

Acesso aberto (Open Access)
Adsorção de ciprofloxacino e norfloxacino em solução aquosa por carvão ativado produzido a partir da casca do cupuaçu (theobroma grandiflorum)
(Universidade Federal do Pará, 2024-09-19) NASCIMENTO, Rafael Alves do; COSTA, Cristiane Maria Leal; http://lattes.cnpq.br/0581730621014796; FARIA, Lênio José Guerreiro de; http://lattes.cnpq.br/7428609361678173; https://orcid.org/0000-0002-9534-9998
The extensive use of antibiotics has caused several negative consequences for the environment and human health. Fluoroquinolones (FQs), present in the aquatic environment, are of particular concern. This study investigated the removal of ciprofloxacin (CIP) and norfloxacin (NOR) from aqueous solutions using activated carbon derived from cupuaçu bark (CAC), an unconventional and low-cost adsorbent. The CAC was characterized physicochemically and the adsorption experiments followed the Box-Behnken design, evaluating the effects of contact time, adsorbate concentration and adsorbent dosage on the removal and adsorption capacity of CIP and NOR. The optimal conditions of the adsorption process were determined by the desirability function, and under these conditions the kinetic, isothermal and thermodynamic adsorption experiments were carried out. CAC showed a similar yield (50.22%) to other activated carbons with H3PO4, low humidity (4.81%) and ash (4.27%). Acidic functional groups were identified in CAC in greater quantities (3.982 mg Eq/g) than basic ones (0.092 mg Eq/g), and the pHPcz was found to be 3.85. A high surface area was quantified (1335.66 m²/g), with an average pore volume and diameter of 0.753 cm³/g and 2.206 nm, respectively. Due to the zwitterionic characteristics of CIP and NOR, adsorption was more efficient at pH 5.0. In this condition, the CAC assumes a basic character and as the CIP and NOR molecules are predominantly in their cationic forms, the electrostatic interaction is facilitated. The optimal conditions for CIP adsorption were: time of 266.40 min, concentration of 192 mg/L and dosage of 0.57 g/L; for NOR, 273.60 min, 186 mg/L and 0.55 g/L. The pseudo-second order (PSO) model and the external mass transfer resistance (EMTR) model best fitted the experimental data, indicating that external mass diffusion was the controlling step of adsorption. The Langmuir model indicated that adsorption occurred in a monolayer, with CIP adsorption capacities of 6.02 mg/g and NOR of 5.70 mg/g. Thermodynamic analysis revealed that the adsorption of CIP and NOR on CAC predominantly involves physisorption. The suggested mechanism for the adsorption of CIP and NOR on CAC may involve electrostatic forces, π-π interactions and hydrogen bonds. CAC regeneration was more effective with NaOH, but after two cycles of use, the percentage of CIP and NOR removal decreased to less than 50%. Thus, CAC proved to be an effective and low-cost adsorbent for the removal of CIP and NOR, also contributing to the reuse of cupuaçu biomass.
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 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 do processo de despolimerização de resíduos de resinas dentárias à base de pmma em diferentes escalas de produção
(Universidade Federal do Pará, 2024-06-26) RIBEIRO, Haroldo Jorge da Silva; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065; BORGES, Luiz Eduardo Pizarro; http://lattes.cnpq.br/8756886156388456; https://orcid.org/0000-0002-2337-4238
In recent years, the increasing use of plastics has brought economic and industrial benefits but has also led to a significant rise in waste, representing a global environmental challenge. In this context, pyrolysis emerges as a promising technology, offering potential solutions to address the growing problem of plastic waste and promote a more sustainable circular economy. This study investigated the thermal decomposition of dental waste based on poly(methyl methacrylate) (PMMA), focusing on the thermodynamic characterization and optimization of pyrolysis processes at different production scales. Thermogravimetric analysis (TG) showed that PMMA waste remains stable up to 200 ºC, with degradation starting as mass loss occurs beyond this temperature. Thermal decomposition was observed to occur in a single stage, with a decomposition peak at 366 ºC, within the range of 327 ºC to 405 ºC, primarily due to radical depolymerization under inert nitrogen and argon atmospheres. Differential Scanning Calorimetry (DSC) analysis revealed an endothermic peak between 370 ºC and 433 ºC, highlighting the complexity of the pyrolysis processes. The energy characterization showed specific values of 423 J/g for total heat, 1748 J/g for gasification heat, and approximately 820 J/g for decomposition heat, indicating discrepancies that require further investigation for a more complete understanding. In studies using semi-batch fixed-bed reactors, a temperature gradient along the bed was observed to have an adverse impact on the liquid yield and MMA concentration, especially in technical and pilot scales, where the gradient was more pronounced due to the thicker bed. Two critical variables were identified: reactor load and power load, both of which decreased as the process scale increased, leading to lower pyrolysis temperatures and negatively affecting MMA production. Additionally, higher temperatures were found at the edges of the fixed bed, which increased gas production and reduced liquid yield. The liquid fraction analysis revealed a predominance of MMA at the beginning of the reaction, with a gradual transition to aromatic hydrocarbons in the final stages, associated with the pyrolysis of residual char, which increased with the scale of production. The results highlight the effectiveness of temperatures below 450 ºC in producing MMA-rich liquid fractions, even under temperature gradient conditions, emphasizing the importance of moderate heating rates for efficient PMMA depolymerization in semi-batch systems. These findings provide valuable insights for reactor design and are essential for the economic evaluation and optimization of PMMA recycling processes through pyrolysis at various production scales.
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)
Biocompósito a partir de PLA, Biovidro e Nanotubos de Carbono por Impressão 3D visando Regeneração Óssea
(Universidade Federal do Pará, 2023-03-31) VASCONCELOS, Esleane Vilela; REIS, Marcos Allan Leite; http://lattes.cnpq.br/8252507933374637; https://orcid.org/0000-0003-2226-2653; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403
Bone involvement promoted by aging and accidents has aroused interest in biomaterials and technologies for bone regeneration purposes. Thus, 3D printing technology gained prominence in the production of scaffolds due to its versatility in the production of complex geometries with interconnected pores. In this work, scaffolds composed of poly (lactic acid) (PLA), bioglass (BV) and carbon nanotubes (NTC) were produced by 3D printing, using hexagonal geometry, similar to honeycomb, interleaved. Poly (lactic acid) is a biopolymer already used in biomaterials, while bioglass has proven to be an excellent strategy for use in bone regeneration due to its excellent properties of biocompatibility, bioactivity and osteointegration, however they have low mechanical resistance and carbon nanotubes have shown excellent mechanical reinforcement in composite biomaterials. Thus, the main objective of this study was to produce and characterize a biocomposite of PLA, bioglass and carbon nanotubes by 3D printing and to study its chemical structure, crystallineity and morphology, using fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction and scanning electron microscope. The thermal stability of the composite was evaluated by thermogravimetry, mechanical properties by compression tests and cell viability was determined by the Alamar Blue test. The bioglass was synthesized by sol-gel method presenting bioactive phases of silicate. The scaffolds were produced by 3D printing with hexagonal structures in honeycomb in PLA, PLA/BV and PLA/NTC that were impregnated with bioglass on its surface. The results of the scaffolds demonstratedinterconnected and well-defined pores, ranging from 130 μm to 800 μm. Raman spectroscopy confirmed the interaction of BV in the polymer matrix through new peaks in the spectrum between 1400 and 2600 cm-1 and the presence of the D, G and 2D bands of NTC. In the compression assay, PLA scaffolds with 2 mm diameter showed higher compression stress of 14.88 ± 2.35 MPa, while PLA/NTC higher modulus of apparent compression, 0.58 ± 0.36 GPa. In cell viability, statistical tests showed that there was no significant difference between scaffolds with 2 and 4 mm diameter. The results reveal promising results for the use of 3D printed composites in bone repair sponges. Thus, we suggest the composite of PLA/NTC of 4mm impregnated with BV on the surface as the best bone substitute, however, the application in implants remains limited in relation to osteogenic integration.
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)
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)
Compósitos híbridos reforçados com tecidos de curauá, carnaúba e aramida com aplicações em blindagem balística
(Universidade Federal do Pará, 2023-01-31) OLIVEIRA FILHO, Edwillson Gonçalves de; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809
The development of effective ballistic armor systems is essential to ensure human and vehicle protection. These shields are usually made up of different materials, such as fiber-reinforced polymeric composites, which are used when a good weight/ballistic protection ratio is desired. In addition, the search for ecologically correct materials, which associate good mechanical performance with sustainability, has been very frequent nowadays. The present work was directed to the study of the mechanical and ballistic properties presented by composites reinforced with lignocellulosic fibers, intended for armoring applications. An investigation was carried out regarding the characteristics of curaua (Ananas erectifolium) and carnauba (Copernicia prunifera) fibers, examining the average diameter, morphological and chemical analyses. The mechanical characterization of the composites was carried out using curaua and carnauba fibers in continuous and aligned distributions through manual production of polyester-fiber composites with 10, 20 and 30%v/v, through tensile, flexural and Charpy impact. From these results, laminated polyester composites were produced for the first time, using hybrid systems with layers of Aramid-Curaua, Aramid-Carnauba and Curaua-Carnauba fabrics, adopting the molding process by cold pressing. All proposed hybrid composites have 30%v/v of fibers and were produced in non-alternating configuration, being submitted to ballistic impact tests considering the level of protection and residual velocity. The ballistic results showed that the Curaua-Carnauba systems were perforated, unlike the Aramid-Curaua and Aramid-Carnauba systems, which were not pierced, which obtained a level I of ballistic protection. In addition, through the residual velocity results, it confirmed the need for fabrics, not blankets, to be used for ballistic applications of these composites. The results are a strong indication of the possible potential of similar hybrid composite solutions.
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)
Energy generation by renewable hybrid sources with pumped storage
(Universidade Federal do Pará, 2022-10-25) FURTADO, Gilton Carlos de Andrade; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
With the increase in the use of renewable sources, the need for energy storage becomes important to ensure that energy generation can meet the demand for electricity. This work aims to explore the potential of energy generation and storage existing in hydroelectric plants and dams. The case of Tucuruí is analyzed, in which the locks and the islands formed in the upper reservoir offer the opportunity to implement renewable systems. In a literature review, similar systems existing in the southern hemisphere are researched, with emphasis on the cases of Brazil and Africa. For the locks, initially, the feasibility of implementing a solar with pumped storage hybrid system is evaluated, comparing it with a purely photovoltaic proposal. In sequence, an optimized system is proposed considering the tariff differences provided in the rules of the Brazilian electricity sector. On the studied island, the advantages of using pump as turbines as a means of energy production and storage are analyzed. The cases studied showed interesting results from a technical and economic point of view, presenting below average payback times, reduced initial investments and ease of maintenance. The physical structure of the already existing locks and dams is favorable to systems of this nature, demonstrating that the expansion of waterway transport in Brazil and in the world must be planned to provide energy storage in sync with renewable generation sources.
Acesso aberto (Open Access)
Estudo da eficiência de uma turbina hidrocinética com difusor projetada para o aproveitamento da energia remanescente da barragem de Tucuruí
(Universidade Federal do Pará, 2023-05-15) LIMA, Adry Kleber Ferreira de; LINS, Erb Ferreira; http://lattes.cnpq.br/5272283698536321; https://orcid.org/0000-0002-6643-5889; VAZ, Jerson Rogério Pinheiro; http://lattes.cnpq.br/1623983294183975; https://orcid.org/0000-0001-6440-4811
Harnessing the remaining energy downstream of dams has recently attained great attention as the kinetic energy transported by the water current is indeed considerable. This work develops a study on the performance of a horizontal-axis hydro turbine under di!user e!ect, in order to quantify the energy gain by comparing both turbines with and without di!user. A 3-bladed hydro turbine with 10 m diameter shrouded by a flanged conical di!user is employed. A numerical modeling using computational fluid dynamics is carried out based on the Reynolds Averaged Navier-Stokes formulation, using the Ÿ – Ê – SST (Shear Stress Transport) turbulence model. The results yield good agreement with experimental and theorical data available in literature.
Acesso aberto (Open Access)
Estudo da incorporação de resíduos industriais, lama vermelha e caulim, nas propriedades de compósitos de matriz poliéster reforçados com fibras de juta e malva
(Universidade Federal do Pará, 2022-07-18) RIBEIRO, Maurício Maia; SILVA, Alisson Clay Rios da; http://lattes.cnpq.br/7389345867032737; https://orcid.org/0000-0001-9186-2287; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403
The Amazon region of Brazil is a major producer of bauxite and kaolin, with the state of Pará accounting for a large national share of the production of these materials. The processing of these raw materials generates considerable amounts of waste that is then stored in sedimentation ponds which can cause serious environmental damage, therefore it is very important to explore reasonable methods of utilizing the red mud and kaolin waste, and thus reduce their landfill volumes. Many recent studies have been conducted and presented various ways of comprehensive utilization of these wastes. Natural fiber reinforced composites with insertion of these industrial wastes have received increasing attention in recent decades, as good specific mechanical properties can be achieved and industrial wastes can be reduced and used in a useful form. In this work, polyester matrix composite materials reinforced by jute and mallow fibers in continuous configuration and aligned at 0° and 90° in the loading direction, and composite materials with insertion of industrial waste were manufactured. The polyester matrix used was a pre-accelerated orthophytalic and cured at room temperature with methyl ethyl ketone peroxide 1.0% by mass. The Jute and mallow fibers were manually cut in length of 300 mm and manually arranged in a continuous manner and aligned and without surface treatment. Fiber composites were produced by vacuum-assisted hand lay-up/vaccum-bagging procedure. The proportions of the fiber volume fraction have varied by 5, 15 e 25 %. The composites with kaolin and red mud residues were manufactured by a manual process in the form of silicone and pressed mold. The proportions of the mass fractions of waste have varied by 5, 10, 15, 20, 25 e 30 %. The residues were characterized in terms of their physical, morphological and chemical aspects and the fibers in terms of their physical and mechanical aspects and the experimental values are similar to that presented from old newspaper. Just as the composites manufactured had their specific mass determined, which resulted in an increase in the average value of the specific mass of the composites with insertion of red mud and kaolin residues. In the case of composites reinforced with fibers of jute and mallow, there was a reduction in the average value when compared to the matrix. Tensile and shear properties were observed for the composites with industrial waste, red mud and kaolin. The composite 5RC exhibited tensile strength value closer to the matrix, as well as for 5RLV, 10RLV and 15 RLV which exhibited the same behavior. For shear strength the composites 10RLV and 15 RLV were closer to the matrix. As well as the composites reinforced with jute fibers 0° presented the highest tensile strength were 0J5, 0J15 and 0J25, exceeding in 2%, 150% and 166% the tensile strength of polyester. For the composites reinforced with mallow fibers 0° showed the highest tensile strength were 0M15 and 0M25, exceeding in 67% and 96% the tensile strength of polyester. For shear strength the composites reinforced with jute (0J15 and 0J25) and mallow (0M15 and 0M25) fibers exceeded the matrix in 201%, 206%, 71% and 144%, respectively. The tensile strength of the three-phase composites (0JRLV, 0JRC, 0MRLV and 0MRC) exceeded the matrix by 129|%, 100%, 54% and 21%, respectively. For shear strength they exceeded the matrix by 49%, 47%, 63% and 52%. Composites with 0-aligned fibers showed satisfactory mechanical behavior for application in composite materials presenting reinforcement characteristics.
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.