Navegando por Assunto "Integral transforms"

Agora exibindo 1 - 5 de 5

Acesso aberto (Open Access)
Análise teórico-experimental da biotransferência de calor em tecidos sintéticos aquecidos por ultrassom
(Universidade Federal do Pará, 2016-04-14) AMORIM, Nelson de Souza; COTTA, Renato Machado; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
The inverse problem of parameter estimation for the bioheat transfer problem in sintetic tissue was analyzed. Initially an experimental analysis was developed by heating a synthetic tissue using a ultrasound transducer. Different temperature profiles were obtained for 3 cases involving intensity variations: 1W/cm2, 1.5W/cm2 and 2W/cm2 for 3 thermocouples positioned along the sintetic tissue. A mathematical model was develeped to represent the experimental problem. The solution of this model was obtained using the Classical Integral Transform Technique (CITT). The Levenberg-Marquardt Method was used to solve the parameter estimation for the attenuation of sintetic tissue. A comparison between experimental solution and the mathematical model was performed.
Acesso aberto (Open Access)
Aplicação da transformada integral generalizada em mancais radiais operando com fluidos não-newtonianos tipo lei da potência
(Universidade Federal do Pará, 2016-02-29) MAGNO, Rui Nelson Otoni; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
This work present a study of the hydrodynamic lubrication of full journal bearings with non-Newtonian lubricants, obeying the power-law model. The formulation of the problem is obtained from the general equations of motion, after being taken over some simplifying assumptions inherent of the problem were taken. The regular perturbation method is applied on the governing equations for determining velocity profiles, and on generalized Reynolds Equation for Non-Newtonian lubricant. Solutions for borderline cases were obtained analytically. Then the generalized Reynolds equation is resolved through the Generalized Integral Transform Technique (GITT). For the calculation a computer code was developed in FORTRAN 90/95 which used the BVPFD subroutine from IMSL Library (2014). Numerical results for operational performance parameters such as pressure field, load capacity, Sommerfeld number, attitude angle, friction coefficient and axial flow rate were established and showed excellent agreement when compared with results available in the literature, for different eccentricities, aspect ratios "" and power-law index "n". Also it was studied the influence of surface texture, using sinusoidal, positive full and half wave roughness (transversal roughness). The transversal positive full wave is best for increasing the pressure, load carrying capacity and axial flow, again the results are excelente agreement with data available in the literature.
Acesso aberto (Open Access)
Estudo da magnetohidrodinâmica em dutos usando transformadas integrais
(Universidade Federal do Pará, 2015-11-27) LOBATO, Benedito; SOUZA, Marcelo José Raiol; http://lattes.cnpq.br/2980566423137880; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
The present work presents the study of magnetohydrodinamics for the outflow of fluids in ducts with different geometric shapes. The integral transforms technics, in this case GITT, were used to obtain solutions of the momentum and energy transfer equations. In each case a hybrid (analytical-numerical) solution was obtained, and they were treated with computational codes that allowed the analysis of the velocity, temperature and entropy fields. The results were compared with the results obtained in classic situations of the literature and also with the actual results, showing the efficiency and capacity of the utilized technique.
Acesso aberto (Open Access)
Solução híbrida da equação de advecção-dispersão em meios porosos
(Universidade Federal do Pará, 2013-03-21) SILVA, Elizeu Melo da; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
This work consists of the hybrid solution of one-dimensional Advection-dispersion Equation for solute in porous media heterogeneous or homogeneous, single component, with coefficients of retardation, dispersion, average speed, production and decay depend on distance traveled by the solute. We will study the cases where dispersion-advection retardation, dispersion, flow rate, production and decay vary linearly as dispersivity assume linear, parabolic or exponential. For the solution of the equation was applied to Generalized Integral Transform Technique. The results obtained in this work show good agreement between the sample problems and their analytical or numerical solutions in the literature and indicate a better match in the use of models in the study of parabolic advection-dispersion in short time, while the linear model converges faster in times of prolonged simulation. The convergence of the series proved to have direct dependence on the length of the field, the dispersion model and dispersivity adopted, converging with terms up to 60, reaching NT = 170, for the heterogeneous cases, using the model of exponential dispersion respecting the criterion adopted 10-4.
Acesso aberto (Open Access)
A técnica da transformada integral na modelagem e simulação de processos de separação de metais por membranas difusivas poliméricas
(Universidade Federal do Pará, 2012-11) CARDOSO, Simone de Aviz; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
The Generalized Integral Transform Technique (GITT) was used in the analysis of the metal extraction process with flat and tubular membranes. For the study of flat membrane, we analyzed the extraction of metals cadmium, Cd (II), gold, Au (III) and palladium, Pd (II) in polymeric diffusive membrane with Aliquat 336/PVC and the equations of chemical species were solved by the GITT methodology. In a second study, the Coupled Integral Equations Approach (CIEA) was used to analyze the same problem. In the study of hollow-fiber tubular membrane, the GITT methodology was also utilized for analyzing the influence of transport conditions for the solute of interest at the interface fluid and membrane phases of a mass separation process in tubular membranes as a function of the governing parameters of the problem. In this type of extraction, liquid extractants are used in the pores of the fiber membrane to facilitate the separation of the mass. In both studies, comparisons were made with those results from the literature demonstrating the potential of this technique in dealing with problems of such natures.