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REM - International Engineering Journal, Volume: 75, Número: 2, Publicado: 2022
  • The importance of urban geological mapping Editorial

    Coelho, Jório
  • Post-Occupancy Evaluation of an educational building: Case study of the ETS-UESC Building Civil Engineering

    Carvalho, Thayse Gama de; Reg, Suânia Fabiele Moitinho da Silva; Oliveira, Maurício dos Santos; Silva, Renan Leão; Lima, Cleverson Alves de; Lins, Vanessa de Freitas Cunha

    Resumo em Inglês:

    Abstract The physical and environmental conditions of educational institutions are determining factors for occupant comfort. The Post-Occupancy Evaluation (POE) presents itself as a methodology for verifying environmental aspects in full use, considering the technical criteria and the users' perception. This article discusses the particularities of the ETS-UESC building, in Brazil, applying POE with an emphasis on the environmental comfort of the classrooms. For this, an exploratory research was carried out where the users' perception of ambience was verified, through the application of targeted forms and on-site measurements of the thermal and lighting conditions using a thermohygrometer and a lux meter, and natural ventilation conditions by design analysis, in the light of current regulations. The opinions were compared with the environmental measurements to identify the limitations of the building and to find the dissonant points. About 85% of users are bothered by the thermal conditions where they are exposed to high daily temperatures, above 30 ºC. In spring and summer, room temperatures are above those recommended by NR 17 standard. The quality of natural lighting is questioned by approximately 80% of users, even having illuminance above the recommended limit of 300 lux in the daytime cycle. How thermal and lighting conditions restrict the use of spaces was proven, making it necessary to discuss active or passive technical solutions to mitigate these problems. Therefore, some factors and technical solutions were pointed out that will assist in the suitability of the project in question.
  • Evaluation of moisture content variation on strength and stiffness properties of Cedrella sp. wood specie Civil Engineering

    Aquino, Vinicius Borges de Moura; Soares, Larissa Soriani Zanini Ribeiro; Ruthes, Heloiza Candeia; Arroyo, Felipe Nascimento; Fraga, Iuri Fazolin; Lahr, Francisco Antonio Rocco; Christoforo, André Luis

    Resumo em Inglês:

    Abstract In order to evaluate the influence of moisture content on wood physical and mechanical properties, the present research analyzed the influence of moisture content variation on Cedrella sp. on 12 strength and stiffness properties, considering 12% moisture content up to Fiber Saturation Point (FSP) were considered. Brazilian Standard consider a correction on wood properties obtained on moisture content different of 12%, reducing the properties. Eight properties from these twelve were significantly influenced by moisture content according to statistical analysis (5% significance level). ANOVA, Anderson Darling and Multiple Comparison tests were used at 5% significance level. Considering that most of properties were affected by moisture content, the equations to estimate wood properties according to moisture decrease are quite precise, but most of estimations were higher than the experimental values at 12% moisture content, indicating the need of a standard review for such estimators, which may lead to an unsafe timber structure design. For a conclusive consideration of moisture content variation influence on wood products, further researches with other tropical wood species are required.
  • Optimum design of steel columns filled with concrete via genetic algorithm: environmental impact and cost analysis Civil Engineering

    Guimarães, Sane Alves; Klein, Diego; Calenzani, Adenilcia Fernanda Grobério; Alves, Élcio Cassimiro

    Resumo em Inglês:

    Abstract The use of concrete-filled tubular columns as part of structural systems has steadily increased throughout the years. The growing demand for structural elements of this nature is a direct result of the possibility to use various cross-section shapes that have increased strength, along with resistance to fire and other corrosive agents. The main objective of this article is to present the formulation for optimizing the design of composite columns in accordance with prescriptions from ABNT NBR 16239: 2013, considering financial cost and CO2 emission during manufacturing as objective functions. A Genetic Algorithm was used to solve three examples of composite tubular columns subjected to combined bending and compression, considering major axis and unsymmetrical bending. The financial cost in Brazilian currency and the CO2 emission in kilograms attributed to manufacturing concrete-filled composite columns were calculated and the optimization procedure was implemented on composite columns featuring CHS, RHS and SHS steel members. This study also considers the different concrete strengths and the optional inclusion of longitudinal rebar. For the cases analyzed, the financially and environmentally optimum design corresponds to a CHS composite column with no longitudinal rebar and the highest concrete strength tested, except when unsymmetrical bending is applied, in which case the optimum solution includes longitudinal rebar. Furthermore, results indicate that structural steel has the highest impact on the CO2 emission of the optimal designs. For the column with longitudinal rebar, the reinforcement steel presents the second highest financial impact, while concrete is responsible for the highest influence on CO2 emission.
  • Contribution to the forecast of horizontal displacements in continuous fight auger piles in granular soil profile Civil Engineering

    Oliveira, Felipe Freitas de; Moura, Alfran Sampaio

    Resumo em Inglês:

    Abstract This article presents a series of propositions for the prediction of horizontal displacements for continuous fight auger piles in granular soil profiles through modifying the parameters Ay and By from the method proposed by Matlock and Reese (1961). Empirical proposals were also presented for calculating the horizontal soil reaction coefficient (nh) for granular soils. Data from ten horizontal static load tests, conducted in the city of Paulino Neves (State of Maranhão, Brazil) were used to develop and validate the propositions. The data regarding results of nine static load tests (PCH 1 to PCH 9) were used to develop the propositions, whereas results for PCH 10 and other data from other studies (Cases A and B) were used in the validation step. Modifying the parameters used in Matlock and Reese’s method resulted in convergent and coherent predictions for all the propositions assessed in this study. In addition, predictions made for piles used in the validation phase yielded results very congruent with experimental displacements.
  • Kinetic study and thermodynamic equilibrium modeling of the Co(II) and Mn(II) bioadsorption using the Rhodococcus opacus strain Mining

    Pimentel, Amanda M. Rodrigues; Quispe, Patricia Reynoso; Torres, Rita J. Cabello; Gonzales, Lorgio G. Valdiviezo; Olivera, Carlos A. Castañeda; Merma, Antonio Gutiérrez; Santos, Iranildes Daniel dos; Torem, Maurício Leonardo

    Resumo em Inglês:

    Abstract Microbial biomass is considered a renewable and environmentally friendly resource. Thus, the research conducted a kinetic study and thermodynamic equilibrium modeling of the cobalt (Co) and manganese (Mn) bioadsorption process using the Rhodococcus opacus (RO) strain as a biosorbent. The inactive biomass subjected to 0.1 M NaOH pretreatment was brought into contact with synthetic solutions of Co and Mn. The experimental data for the Co(II) and Mn(II) bioadsorption process were fit to the Langmuir model with kads of 0.65 and 0.11 L.mg-1, respectively. A better statistical fit was also obtained for the pseudo-second order kinetic model (R2Co(II) = 0.994 and R2Mn(II) = 0.995), with 72.3% Co(II) and 80% Mn(II) removals during the first 10 min. In addition, a higher affinity of RO for the Co(II) ion was observed, with maximum uptake values of 13.42 mg.g-1; however, a higher adsorption rate was observed for Mn(II) ion (k = 0.21 g.mg-1.min-1 at 318 K). The bioadsorption process was spontaneous and dependent on temperature, being endothermic and irreversible for the Co(II) ion (∆H = 2951.91 J.mol-1) and exothermic and reversible for the Mn(II) ion (∆H = -2974.8 J.mol-1). The kinetic and thermodynamic equilibrium modeling allowed to identify the main mechanisms involved in the biosorption process of both metals.
  • Performance analysis of the beneficiation process of bauxite from the Juruti Mine. Industrial sampling and performance evaluation Mining

    Paiva, Monica Katyusca Nunes de; Delboni Junior, Homero; Jatobá, Thiago

    Resumo em Inglês:

    Abstract Sampling campaigns were conducted at the industrial bauxite wash circuit of the Juruti Bauxite Mine in Pará, Brazil. The beneficiation circuit consisted of crushing, scrubber washing, wet screening, hydrocyclone classification, and fltration. Considering laboratory processing of samples and statistical analyses of historical operation databases, mass balances were obtained. Integrated analyses of historical databases, mass balances and operating parameters enabled the calculation of performance indices, which constitute the basis for the identification and hierarchy of the bottlenecks in terms of washability efficiency; that is, removal of the fraction below 0.037 mm. Typically, the focus of bauxite ore concentration in the Amazon region is the removal of the 0.037 mm fraction in the concentrate streams via disaggregation and mud washing. Consolidated mass balances indicated consistent values based on the size of the sample particles and percentage of solids, as well as the values obtained from the integrated information systems of the plant; this consistency indicated the stability and representativeness of the process conditions during the sampling campaigns. The base case of the Juruti plant operation, from which the performance indices that allowed the quantification of the efficiency of each process step was calculated, was obtained as a result.
  • Characterization of micaceous minerals occurring in phosphate ores in Brazil: emphasis on the interstratified phyllosilicates Mining

    Carvalho, Juliana Angélica Evangelista; Brandao, Paulo Roberto Gomes; Henriques, Andreia Bicalho

    Resumo em Inglês:

    Abstract Micaceous minerals were characterized in three phosphatic ores from mines in Western Minas Gerais State, Brazil, all having complex chemical and mineralogical compositions, with emphasis on interstratified phyllosilicates. Knowledge of the relationship between the physical and chemical characteristics of the phyllosilicates contributed to a better understanding of the physicochemical processes in the mineral processing stages. Characterization of the minerals was carried out mainly by X-ray diffractometry (XRD), which allowed identifying vermiculite and three interstratified phyllosilicate phases. These minerals presented regular stratification of the unit cell, with different percentages of vermiculite and mica. Complementary studies by scanning electron microscopy (SEM) with EDS microanalysis, thermogravimetry and chemical analysis confirmed the identifications by XRD.
  • Development of innovation routes for iron ore using high intensity magnetic separators Mining

    Menezes, Késsius Bortolan; Gonçalves, Ana Vitória de Moura; Rodrigues, Otávia Martins Silva; Reis, Érica Linhares

    Resumo em Inglês:

    Abstract The mineral processing of low-grade iron ores commonly generates large volumes of slime, which are disposed as tailings. Modern mining requires strives to eliminate the use of tailings dams in a maximum effort to increase metallurgical recovery, the security and reduction of the operational cost. This research aims for the recovery of iron contained in the slime, which consists of a material with 38% Fe and <40 µm, originating from the desliming cyclones. Pilot tests were performed on the Wet High-Intensity Magnetic Separator (WHIMS) and on the Vertical Ring Pulsating High Gradient Magnetic Separator (VPHGMS) considering different configurations in terms of operating parameters and routes. The best results were obtained for VPHGMS with an iron content in the concentrate of 67.06% and mass and metallurgical recovery of 32.42% and 56.86%, respectively. In the best condition tested, around 540 thousand tons of concentrate can be incorporated into production and has great environmental relevance.
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