Programa de Pós-graduação em Engenharia Elétrica e da Computação
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Item Proposta e avaliação de um modelo computacional de gerador central de padrões(Universidade Federal de Goiás, 2011-06-02) BORGES, Marco Aurélio de Faria; VIEIRA, Marcus Fraga; http://lattes.cnpq.br/4153462617460766The concept of Central Pattern Generator-CPG can be described as neural network capable of producing coordinated rhythmic locomotor activity apart from any external rhythm or sensorial stimuli. As this group of neurons are autonomic and are located in the spinal medulla, is experimentally observed that brainless animal‟s exhibit robotized locomotor activity, for its march has no defined direction nor respond to any obstacles. Studies has shown that is possible to activate this specialized networks using specific drugs or electric stimuli depending only of the access area as brainstem, medulla or some brain areas. For this paper many models proposed in current literature were evaluated, in its majority conceptual models. Within this models the Rybak (2006) computational model was chosen to be reproduced and evaluated regarding its robustness. The model in question consist in a CPG based in experimental data collected in cats and it posses two level of neurons based in the half-center models in its structure, the Rhythmic Generator-RG and the Pattern Formation-PF. This groups control the activity of the motoneurons flexors and extensors in an articulation. For its implementation were necessary a simplification in the original model and new parameterization of the variables. The implemented model allows a locomotor activity simulation produced by the CPG when stimulating a Mesencephalic Locomotion Region. Two protocols of variation of conductance inn GR were applied intending to evaluate its strength. The results show that the CPG computer model created operates within physiological values in variations up to . This model presents an adaptation in the first and the current is the current that plays a major role in the occurrence of outbreaks. The conductance has a direct relationship with the period as a result of its increase, a decrease in frequency of the bursts occurs. The conductance of has an inverse relationship with the period and as a result of its increase, a decrease in the period and increased in the frequency of the bursts occurs. The conductance has a direct relation with the period of the bursts before the 100% and a reverse relation after 100% of the reference value. The default behavior extensor/ flexor dominant not only depend on the synaptic weight of RLM, but rather the result of all the conductance values that make up the neuron GR.Item Estudo empírico de avaliação inteligente computadorizada de questões abertas baseado em colaboração(Universidade Federal de Goiás, 2009-09-12) CORRÊA, Kleber Pullig; MACHADO, Paulo César Miranda; http://lattes.cnpq.br/8831309316416795This research submits to experimental tests in real-world environment, the Conexionist Collaborative Intelligent Evaluation System idealized by Martins (2004) and tested with simulations by Guimarães (2004), who have noticed consistent and promising results when dealing with synthetic datas. The system explores the Learning Theory by Kolb (1984), Peer Collaboration Evaluation and Artificial Intelligence (multilayer perceptrons neural networks), which are capable to apply and correct tests with open (free) questions. To get a real-world data, some students from the course of Engineer registered at Universidade Federal de Goiás (UFG) on the period of june 2008 to july 2009 were taken in heterogeneous groups composed by men and women in age from 16 to 26 years old and at least 18 students per test. The software SAICOweb, developed specifically to this data collection, allows the computerized evaluations of open (free) questions, by using methods and stages described at Guimarães (2004) research. SAICOweb system were experimental validited in a satisfactory way by an unique group composed by 38 students (by using two tests with 08 open questions each). The analisys of the results with Pearson correlation shows strong association (0,81) between grades given by SAICOweb and the human grades (corrected by professors). Another important result is the satisfaction of professor and students when evaluating Software SAICOweb, evaluation method, pedagogical experience and anonymity. Specific itens were identified and suggested as future updates, when more experimental tests should be designed to validade other aspects of the System.Item Adaptação de conteúdo para múltiplos contextos(Universidade Federal de Goiás, 2011-03-15) RICARDO QUINTA, Marcelo; LUCENA, Fábio Nogueira de; http://lattes.cnpq.br/6428011745982173The mobile technology The increasing of mobile technology usage popularity for internet access enables educational content access in anyplace, anytime. However, the use of this flexibility requires considerable effort, because the content sponsor must produce not just one material version, but as many ones as the number of different devices used. This work discusses the content adaptation support in actual learning management systems, the problems associated with the use of different devices to access educational content and presents Odin. The Odin solution offers transparency on automatic adaptation of audio, video image ant text for suitable adhibition of adapted content in different machines, SCORM support and can be described as an extension in learning management systems application servers.Item Amplificação sináptica e interações não lineares na arborização dendrítica de modelos de motoneurônios(Universidade Federal de Goiás, 2010-04-23) RODRIGUES, Fábio Barbosa; VIEIRA, Marcus Fraga; http://lattes.cnpq.br/4153462617460766From motoneurons models (MN) of complex geometry and structure, able to reproduce the characteristics of a real motoneuron, the aim of this work is to verify the functional differences between proximal and distal synapses, investigating the nonlinearities in passive equivalent dendrites of motoneuron models and to study the influence of persistent calcium channels type L (Cav1.3), present in the dendrites, in the synaptic amplification. The original models developed by Vieira and Kohn (2007), implemented in C++, were expanded. This allowed to accomplish tests in order to verify the functional differences of synapses that occur near the soma and along of the dendrites. Persistent channels of calcium (CaV1.3) were modeled in dendrites and the influence of these channels in the amplification of the synaptic currents along the dendrites was verified. Finally, the nonlinearities of responses degree in the dendritic tree for different synaptic activation was evaluated. In order to verify the functional differences between proximal and distal synapses pure sinusoids were injected in different dendritic compartments of the models. The results showed attenuation at higher frequencies and the cutoff frequency is smaller as we move along the dendrites far from the soma. The influence of persistent calcium channels was verified comparing the functional differences between proximal and distal synapses along of the soma, with and without them. The initial results showed a notable amplification of synaptic activation. Nonlinear interactions were evaluated using sinusoids synaptic inputs with different frequencies in two or more equivalent dendrites in different compartments. The frequency spectrum of the current between the initial segment and the soma was analyzed by comparing the peak amplitude of harmonics and spurious bands with the peak amplitude of the fundamental frequency of smaller amplitude: the smaller these differences were, greater was degree of nonlinearity between synaptic activation in different dendritic segments. The results showed a high degree of nonlinearity between the dendrites. The cases where the synaptic conductance was varied showed greater degree of nonlinearity in relation to the cases in which the synaptic current was varied.