Programa de Pós-graduação em Engenharia Elétrica e da Computação
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Item Uso de sistemas tutores inteligentes na compreensão de leitura(Universidade Federal de Goiás, 2009-11-28) BORGES, Fabrícia Neres; BRITO, Leonardo da Cunha; http://lattes.cnpq.br/6660680440182900Brazilian students have achieved poor results in the National Student Performance Exam (ENADE) in 2006. ENADE has shown reading is badly cultivated among undergraduates. The low interest on reading is justified by the fact that most of students have jobs and are enrolled in evening courses, without enough time to studies. The current research proposes the use of intelligent tutoring systems to improve student reading comprehension. The main goal is to develop the technique of underlining among undergraduates to assist in the analysis of academic texts. Two groups of students, A and B, participated in data collection. The difference between the groups is the amount of exercises performed in each group. Students of Group A have received 20 exercises with four levels of difficulty. In Group B, an Artificial Neural Network, Multilayer Perceptron (MLP), decides the amount of exercises that the student must perform at each level of difficulty by controlling what is the next exercise after each exercise is finished. The approach used in Group B adapts to the characteristics of knowledge retention of each student. Therefore, the tutoring system adapts the degree of exercise difficulty to the student. Statistical data analysis has indicated significant differences between groups A and B.Item ROTEAMENTO AUTOMÁTICO DE ALIMENTADORES NO PLANEJAMENTO DE SISTEMAS DE DISTRIBUIÇÃO DE ENERGIA ELÉTRICA(Universidade Federal de Goiás, 2008-11-07) ROCHA, Adson Silva; BRITO, Leonardo da Cunha; http://lattes.cnpq.br/6660680440182900The present work deals with the problem of planning the distribution system of electricity and is divided into three parts: Problem Definition, Resolution Approaches and Results and Conclusions. The energy distribution networks are of great economic importance in countries like Brazil. On one hand, there are fixed costs of physical installation and operation of the network, mainly due to the costs of energy losses and, secondly, the natural obstacles along the possible passages of network s links. The large amount of these costs, together with lack of efficient methods when it comes to real applications in the matter, justify the development of this research. The study of such aspects, the precise definition of the problem and the reasons that motivated this work can be found on the first part of this work. The second part shows the approaches for resolution. Three proposals methods were adopted: the first uses the algorithm Prim associated with the method Nelder-Mead Simplex. In the second proposal uses Dynamic Programming and, finally, we take the metaphor of Ant Colony also associated with the Nelder-Mead Simplex. The results, presented at the third part of this work, demonstrated the effectiveness of the proposed methods, especially the good compromise between performance and applicability obtained by the third proposal.Item A Utilização de Redes Neurais Artificiais na Estimação da Cobertura do Sinal de Televisão Digital(Universidade Federal de Goiás, 2009-08-21) SILVA, Douglas Dias da; DEUS JÚNIOR, Getúlio Antero de; http://lattes.cnpq.br/8531659368461322THIS works presents information about signal intensity obtained on field and from simulations for one-seg and full-seg receptions, the city of Goi ania. The values obtained from measurements were used for a comparisson among propagation models that are presented in literature, and the goal is to determine the real condition of digital TV signal in the region of Goi ania. The propagation models presented are available in literature and can be implemented in digital transmission system. The studied models were Free Space model, Log-Distance model, Hata model and ITU-R P.1546-1 method, and the objective was to determine the signal intensity of digital television transmission in the city of Goi ania (RAPPAPORT, 1996) (UNION, 2003). Focusing on the development of a tool for signal intensity estimation, some researches were done about neural networks theory and its applications. Perceptron and Multilayer Perceptron were the analised architectures, emphasyzing on the last one and on its supervisioned trainning through the backpropagation error algorithm (HAYKIN, 2001). The Brazilian Digital Television System was described by reference rules made by Associa¸c ao Brasileira de Normas T´ecnicas, which has detailed its transmission system and reception devices (T´ECNICAS, 2008a) (T´ECNICAS, 2008h). Measurements of signal intensity for one-seg and full-seg reception methods were made on field in the region of Goi ania. These measurements followed the sugestions presented by Report ITU-R BT. 2035-1 and it used a radiofrequency analyzer and a Global Positioning System (GPS). With the obtained data, the digital signal covering situation in the city of Goi ania was mapped, which revealed a lower intensity level to the studied models. A tool for signal intensity estimation was developed using Artificial Neural Networks, which was trained with the dada obtained from the performed measurements. This tool was used to obtain the signal intensity for several proposed scenarios. The signal intensity estimation for the scenario that has tree density and target absence distinguished as the one that was closest to the reality of Goi ania, which is a consequence of high density of trees.