Navegando por Assunto "Mathematical model"

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Acesso aberto (Open Access)
Desenvolvimento de sistema computacional integrado de dimensionamento e representação gráfica de canais de macrodrenagem
(Universidade Federal do Pará, 2022-05-23) MARTINS, Vania Carla Dias; PEREIRA, José Almir Rodrigues; http://lattes.cnpq.br/9918600634569244; https://orcid.org/0000-0002-3144-1787
Develops an integrated computer system for the design and graphic representation of macrodrainage channels, including the hydrological, hydraulic, hydrodynamic design steps and graphic design elements. The system conceived and named SIDCAM was developed with a central model built in Java (MACRO 1.0), which is integrated with three external software, Google Earth, HEC-RAS and AutoCAD. For this, the research was carried out in three stages: (1) identification of methods and software, necessary for the development of a macrodrainage project; (2) development of the software in Java, for the hydrological and hydraulic design stages (phase 1), and, development of tools for integration, import and export of data, between the hydraulic module and the HEC-RAS and AutoCAD software (3 ) evaluation of the functionality and reliability of SIDCAM, through its application in the case study of the macrodrainage project of Tucunduba, Belém/PA. SIDCAM is composed of four modules: the hydrological module, for the generation of hyetograms and project hydrographs, using the alternating blocks and triangular hydrograph (SCS) methods; the hydraulic module, for making the geometric design of the channel and the coincidence of flow peaks with high tide peaks; the hydrodynamic module, to validate the SIDCAM geometric design; and the graphic module, for the automatic production of editable graphic pieces, of longitudinal and transverse profiles. In addition to the modules, import directories of IDF and tide gauge curves were built, fed by two databases, for IDF coefficients of 165 Brazilian municipalities and tide gauge curves of 334 stations of the Brazilian Navy. In the analysis of the water levels in the channel, simulated by the developed system, most of the results were classified as “Good” and “Very Good”, with Nash-Sutcliffe coefficients greater than 0.97, a minimum percentage error of 1.19% and a maximum of 14.72%. In view of these results, the proposed tool is promising, especially because it is a model that concentrates a good part of the processes necessary for a macrodrainage project, in a single integrated structure, thus filling gaps left by current models, which have a dissociative approach to the different stages of the project.
Acesso aberto (Open Access)
Determinação de parâmetros de transferência de massa do processo de extração supercrítica
(Universidade Federal do Pará, 2013-03-01) SANTANA, Ádina Lima de; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065; ARAÚJO, Marilena Emmi; http://lattes.cnpq.br/8983914018546682
Supercritical fluid extraction of liquid and solid materials sparked interest for industrial applications in recent decades, particularly under the concept of green chemistry and biorefineries, so it is essential to make a modeling of this process in order to optimize and simulate operating conditions process. The objective of this work consists in determining the parameters of mass transfer of supercritical extraction of solid matrix by employing carbon dioxide as solvent, from kinetic data extraction and five systematic evaluation of mathematical models to describe the kinetics extraction of oils from the peel and pulp of buriti, oil from açaí and oleoresin from turmeric, measured in Supercritical Extraction Laboratory, Faculty of Chemical Engineering (UFPA) in order to contribute to the study of scale-up and production cost analysis. Were evaluated the models of Tan and Liou, Goto et al. (1993), Martinez et al. (2003), Esquível et al. (1999), and Sovová (1994). The extraction kinetics modeling was performed using computer applicatives developed and validated in this work from different experimental data published in the literature. Facing 40 kinetic measurements with different extraction equipment, bed settings, types of raw materials, preparation of materials, pressure and temperature and other process parameters (especially income and global flow solvent), was built an overview of results ability of the models on the mass transfer in more different curves describing the overall extraction. Generally, the model Goto et al. (1993) and Sovová (1994) showed the best predictions to experimental data of raw materials treated in this work with smaller values of chi-square, relative errors, range and standard error and R2 values close to unity.
Acesso aberto (Open Access)
Modelagem e simulação da solidificação direcional vertical ascendente de ligas binárias: solução via método das linhas
(Universidade Federal do Pará, 2015-07-08) GIRARD, Cássia Karina Teixeira; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
Method of Lines (MOL) was used to analyze the equations that describe the heat transfer process during solidification of binary alloys. The physical model consisted of simulating the solidification of these alloys based on experimental results available in the literature, obtained in a vertical upward directional solidification device. A computer code based on FORTRAN 90/95 programming language, using the subroutine library DIVPAG IMSL, was developed to numerically solve ordinary differential systems of equations. Thermal variables such as growth rate of liquidus isotherm (VL), thermal gradient (GL) and cooling rate (TR) were determined from the cooling curves for alloys of three different systems used in this study (Al-Sn, Al-Cu and Sn-Pb). Finally, comparisons of numerical results obtained in this study with literature values were performed, demonstrating the potential of the technique used in treating such problems.
Acesso aberto (Open Access)
Proposta de modelo matemático e estimativa de parâmetros cinéticos da lixiviação da lama vermelha através de técnicas bayesianas
(Universidade Federal do Pará, 2019-09-13) VIEGAS, Bruno Marques; ESTUMANO, Diego Cardoso; http://lattes.cnpq.br/5521162828533153; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
Red mud, a residue from the alumina production industry, is obtained during bauxite processing through the Bayer process. Because it is generated in large quantities and has many oxides of industrial interest, the kinetics of red mud leaching have become the object of study by many researchers. This work proposes the mathematical model and the estimation of the kinetic parameters of the leaching of the red mud, using the Markov Chain Monte Carlo method with the Metropolis-Hastings algorithm. To estimate the parameters, actual data were used, obtained from different experiments involving red mud leaching with sulfuric acid. Based on the shrinking core model, a mathematical model was proposed, in terms of a system of coupled differential equations, aiming to represent the kinetics of the waste leaching. The proposed mathematical model was validated by reproducing experimental data and the use of Bayesian statistics was adequate.