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Estudo da transferência de calor e massa no processo de secagem em leito vibro-fluidizado
(Universidade Federal de São Carlos, 2003-09-05) Oliveira Júnior, Antonio Batista de; Freire, José Teixeira; https://lattes.cnpq.br/2270677706718167
Drying processes in fluidized and vibro-fluidized beds are nowadays being widely investigated in the literature, because such beds offer many advantages over other types of dryers. The purpose of this work is to contribute for the research in this area by presenting an extensive investigation of the drying process in fluidized and vibro-fluidized beds. The following topics were investigated in this work: a) fluid dynamic studies in fluidized and vibrofluidized beds were carried out using particles of alumina and silica-gel as inerts. The effects of variables such as the frequency and vibration amplitude (which are combined in a dimensioless vibration number), height of the bed and particle diameters on the fluid dynamic behavior of both beds have been analyzed. Simultaneously, an analysis of the fluid dynamic behavior for these beds was carried out using measurements of standard desviations of the pressure drops in the beds as a function of the superficial gas velocity. The results show that in both beds the dimensioless vibration number has a strong influence on the fluid dynamic behavior of the bed of particles. Besides, the increase in the height of particles in the bed, as well as in the particle diameters affects significantly its characteristic curves; b) equilibrium isotherms for alumina and silica-gel particles were obtained experimentally using the static method. Some equations for equilibrium isotherms available in the literature were compared to experimental data and the best fitted model was obtained using a technique based on non-linear estimation of the parameters. The results show that the equation of Sabbah provided the best fitting for both particles of alumina and silica-gel; c) the drying kinetics for alumina and silica-gel were obtained from experimental data for the drying of a thin layer of particles in a fixed bed. The best model for the drying kinetics came from a semi-empirical equations presented in the literature, using a non-linear estimation of parameters technique. The results show that the equation from Mancini provided the best predictions for experimental data of alumina and silica-gel; d) heat an mass transfer coefficients in the fluidized and vibrofluidized beds were estimated using the methodology proposed by Kmiec (1975). In the range of variables investigated, the results show that the heat and mass transfer coefficients for the vibrofluidized beds have not increased significantly as compared to the values obtained in the fluidized beds; e) the moisture content and temperature profiles of the particles were estimated using the mathematical model proposed by Massarani and Silva Telles (1992) with the heat and mass transfer coefficients obtained experimentally. For the range of conditions investigated, the mathematical model has not provided good predictions for the moisture content profiles, but in the other hand, it provided reasonable good predictions for the temperature profiles of the particles.
Evolução da forma e encolhimento de um sistema gel durante a secagem por convecção forçada
(Universidade Federal de São Carlos, 2003-09-05) Arrieche, Leonardo da Silva; Sartori, Dermeval José Mazzini
Knowledge of the shape evolution and shrinkage of a spherical gel system during drying by forced convection significantly enhances the understanding of this process under the vision of the transport phenomena. This work consists in the development of a gel system, with spherical geometry, which allows analyzing the effect of the fluid flow, in the boundary layer, on the moisture transport, shrinkage and on the shape evolution of the sample, during drying in an air stream forced convection equipment. The shrinkage was observed through the capture of images, used for the calculation of shape factors. The process was evaluated under a laminar flow (based on particle diameter), with a agar concentration of 1.5 and 3% (wet basis), fluid velocities varying from 1.0 to 2.0 m/s and initial particle diameters of 1.61.10-2 and 2.66.10-2 m, being the temperature maintained at 50 0C. The results confirmed with good reproducibility, proved statistically, that the circularity and specific mass of the samples decrease according to the formation of accentuated two-dimensional moisture profiles, for moisture contents lower than the critical value. The difference between the maximum and minimum diameters of a sample, during the process, evidenced the variation of the mass transfer rates between the previous and subsequent areas. It was inferred that during the constant drying rate period, the analysis is pondered in relation to the moisture transport, with the circularity and specific mass of the samples staying approximately constant. The gel system used allowed to reach the proposed objective, in a selective way, representing materials intensely affected by the shrinkage.
Reengenharia de interfaces utilizando Wrapping
(Universidade Federal de São Carlos, 2003-09-05) Affonso, Frank José; Penteado, Rosângela Aparecida Dellosso; https://lattes.cnpq.br/4061946080136286
With the technological evolution and the increasing utilization of the Internet, companies and governmental institutions have been looking for modern solution to replace and improve their legacy systems. These kind of solutions require high investments, being able to use the reengineering process in these cases. A maner to modify these systems is through reengineering of their interfaces, by wrapping of their logic. This technique preserves the native environment of system and its functionalities, reducing in time and cost the reengineering process. To support the migration of legacies systems in a general way, there is an Interface Reengineering Process (IRP), whose accomplish the wrapping of its functionalities and connect them with a new user Web interface. This Web interface connects itself with the identified components of the legacy system following the special resources that they offer. The IRP is summarized by the study of the interface and logic of the system. In this way, it possible to accomplish the system organization for the wrapping to be done, which is composed by the legacies functionalities covered by a new software layer. This new layer makes possible the communication with the new user interface, which has developed according to the usability criteria. The systems used as case studies were developed using Delphi environment, with or without object orientation characteristics. In this work only systems developed without object orientation characteristics are presented in details. With the use of the new process proposed here, the interface can be developed in any paradigm, while the legacy code remains as the original, simplyfing the system maintenance.
Investigação do modelo de aprendizagem híbrido genético-baseado em instâncias
(Universidade Federal de São Carlos, 2003-09-05) Nardin, Luciana de; Nicoletti, Maria do Carmo; https://lattes.cnpq.br/6454154048263145
This research work investigates the contribution of genetic algorithms to instance based learning methods, particularly k-NN, IB1 and IB2. The main focus of the investigation is to optimize the performance of three algorithms by means of a genetic algorithm. A computational system that implements each method and its genetic variant is described. Results of experiments in some knowledge domains are presented and analised.