Programa de Pós-graduação em Engenharia Elétrica e da Computação

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Acústica aplicada no desenvolvimento de equipamentos para agricultura de precisão
(Universidade Federal de Goiás, 2022-07-08) Furriel, Geovanne Pereira; Calixto, Wesley Pacheco; http://lattes.cnpq.br/9073478192027867; Calixto, Wesley Pacheco; Silva, José Geraldo da; Araújo, Wanderson Rainer Hilário de; Jakelaitis, Adriano; Cruz Junior, Gelson da
This work presents methodology for development of precision agriculture equipment based on acoustic and vibration techniques. The proposed methodology uses the scale reduction method to simulate the induced vibration and the direction of sound pressure fields. After analyzing the scale-down model, the prototype is built in real dimensions to validate the proposed system. Two acoustic induction systems are designed and evaluated, one for applying phytosanitary products and the other for selective fruit harvesting. When applying the phytosanitary product, there is a reduction in drift and an increase in leaf coverage by approximately 45%. In the selective harvest, the proposed method is analyzed, and approximately 40% of the fruits were harvested at the appropriate maturation stage. The acoustic techniques presented applied to agriculture are promising for developing equipment for handling and harvesting in precision coffee farming. The results indicate that using acoustic techniques promotes the reduction of the inherent wear of the harvest in the plants.
Adaptabilidade temática em sistemas tutores inteligentes híbridos
(Universidade Federal de Goiás, 2008-02-23) QUINDERÉ, Pedro Sérgio Gomes; NALINI, Lauro Eugênio Guimarães; http://lattes.cnpq.br/7555089672749145; MARTINS, Weber; http://lattes.cnpq.br/3123848470517021
In the context of efficient information transmission among people and, particularly in the helping of learning and training processes, this investigation presents results on the use of the technology of Hybrid Intelligent Tutoring Systems, based on artificial neural networks and expert rules, developed by Martins [MEA 2004], Melo [MEL 2003] and Meireles [MEI 2003]. Due to the fact that, in its initial empirical validation, neural training data has been originated from courseware in Introduction to Data Processing , some doubts have remained on the applicability of the trained neural network to other scenarios. The present production has approached these issues by the formalization of the content format and by presenting promising empirical results in two other scenarios: Scientific Methodology and Biological Rhythms . Results were analyzed by non-parametric methods with 5% significance. They reinforce the hypotheses that the studied tutoring system is efficient, able to reduce differences of distinct groups and shows thematic adaptability actually
Adaptação de conteúdo para múltiplos contextos
(Universidade Federal de Goiás, 2011-03-15) RICARDO QUINTA, Marcelo; LUCENA, Fábio Nogueira de; http://lattes.cnpq.br/6428011745982173
The 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.
Aferição de usabilidade de interfaces assistivas sob o prisma da computação afetiva
(Universidade Federal de Goiás, 2022-04-07) Mezencio, Rovilson; Lemos, Rodrigo Pinto; http://lattes.cnpq.br/3333000136853156; Lemos, Rodrigo Pinto; Gomide, Renato Sousa; Alves, Ricardo Henrique Fonseca; Guedes, Leonardo Guerra de Rezende; Vasques, Thiago Lara
The usability of interfaces is connected to the perception and emotion of each user. The way each individual feels the world around them is their own. Assess or test an interface from a cognitive point of view and measure with a simple note whether or not it can be improved in a generic way without discovering if groups of individuals need special attention or if they react in a similar way, it is already an ancient science. Affective computing arises to study whether these perceptions, emotions, attitudes and behaviors can be measured and how this can improve interfaces so that there is greater personalization in the use of interfaces. Assistive Software interfaces need to be more personalized than interfaces are general-purpose. Each user has their specific difficulty and different personalities. Psychometric tests in their variety and scientificity have been used to classify sets of users and verify if their needs can be grouped. The idea now is to find out if people within groups with similar skills, competences, personalities, way of acting and thinking may have similar technological needs when using some technology. This work raised the techniques and methodologies for usability assessment of assistive or non-assisted interfaces. Then, a bibliographic research was carried out to understand which would be the best personality classifier available in Portuguese. Furthermore, methodologies were sought in Affective Computing to assess emotions activated in the use of an available and free assistive tool. Then, an attempt was made to assess the quality of an interface, as well as the grade or level it reached Also, the perceptions caused by its use were verified and if there is a way to make a grouping based on the personalities mapped by an inventory based on the Big Five. A survey was carried out with 96 (ninety-six) participants who were grouped into four different personalities in order to verify if different personalities have similar cognitive and emotional perceptions when performing a task in an assistive tool. Compiling the data and using specific statistical techniques for the correlation study, it is concluded that there are indications that people with the same personality, classified using the Personality Characteristics Inventory-ICP, a national method based on the Big Five , may have similar cognitive and emotional perceptions.
Algoritmo de Policiamento de Tráfego para Redes OFDM/TDMA WiMAX Baseado em Modelagem Multifractal e Cálculo de Rede
(Universidade Federal de Goiás, 2011-09-29) SANTOS JUNIOR, Josemar Alves dos; VIEIRA, Flávio Henrique Teles; http://lattes.cnpq.br/0920629723928382
The multifractal modeling is more appropriate in describing some features finding in traffic flows in real networks than other models. This work investigates the behavior of the traffic modeling based policing algorithms found in the literature (Leaky Bucket, Fractal Leaky Bucket, Gaussian Multifractal Leaky Bucket) regarding the buffer utilization, the efficiency for the use of buffer efficiency in describing the accumulated traffic (envelope process), packet dropping and data loss (bytes). First, we compare the envelope process of the considered policing algorithms and the proposed algorithm MAPM (Multifractal Arrival Policing Mechanism), with traffic without policing. Next, it was calculated the system loss rate for a finity buffer system with and without policing algoritm. Using the deterministic Network Calculus, it is also estimated the average queue length (backlog) and delay of bytes by applying the concept of the Min-Plus algebra that presents some differences against the conventional algebra. The proposed policing algorithm was applied to a transmission system based on OFDM (Orthogonal Frequency - Division Multiplexing) / TDMA (Time Division Multiplexing Access) system, where it was evaluated the network performance of the considered policing algorithms. Simulations were carried out with real wireless network trace (Wi-Fi) and wired network trace in order to demonstrate the efficiency of the algorithm proposed in relation to policing algorithms in the literature. The simulations shown the efficiency of the MAPM policing algorithm with traces from wired and wireless networks. We also propose the use of deterministic Network Calculus associated to multifractal envelope process to analyze the traffic behavior in terms of delay and backlog before policing algorithms application in the network. Finally we present the results of buffer utilization, link utilization, delay and backlog to a WiMAX system where the policing algorithm MAPM in general shown delay and backlog increasing in the traffic compared with anothers algorithms and low link utilization
Algoritmos bioinspirados aplicados ao problema de alocação de geração distribuída
(Universidade Federal de Goiás, 2023-02-02) Santos, Josephy Dias; Garcés Negrete, Lina Paola; http://lattes.cnpq.br/3707701912481754; Garcés Negrete, Lina Paola; Belati, Edmarcio Antonio; López Lezama, Jesus Maria; Brito, Leonardo da Cunha
This work presents the performance comparison of different meta-heuristics, two classic and one modern. The implemented optimization algorithms aim to solve the distributed generation allocation problem in electricity distribution networks widely known in the literature. The study confronts the following computational techniques applied in algorithms classified as bioinspired: the Chu-Beasley Genetic Algorithm (AGCB), the Symbiotic Organisms Search (SOS) and the Coronavirus Optimization Algorithm (CVOA). The allocation of DG units in the Electric Power System gives the system advantages and disadvantages. Among the advantages we can mention: reduction of power losses, expansion of investments in the electrical sector, expansion and diversification of the electrical matrix, mostly, use of clean energy and indirect benefits such as job creation. Among the disadvantages are difficulties in charging for the use of the electrical system, possible incidence of undue taxes, need to change operating procedures, indiscriminate elevation of the voltage profile if the penetration factor is high and the allocation of DG is random, increase in short circuit levels, failures in the protection operation, among others. The network operating conditions are verified through the forward and reverse sweep method, specifically using the Power Sum Method. The objective function, in the optimization model for the allocation of distributed generation, aims to minimize the total losses of active power in the system. For the implementations, the allocation of modules (100, 200 and 500kW) of distributed generation is considered, with the number of these modules limited by the penetration factor of each network. The specialized algorithms are tested on four electrical systems: 10, 34, 70 and 126 buses. The results obtained show the rapid convergence and robustness of the AGCB of the implemented algorithms, the same cannot be said about SOS, which had an intermediate performance. The CVOA, as an unprecedented contribution in this work, presented a lower performance than expected, largely due to its nature and architecture of the proposed modeling.
Algoritmos de inteligência computacional aplicados à otimização de sistemas de controle em acionamentos elétricos
(Universidade Federal de Goiás, 2023-03-29) Santos, Guilherme Fernandes dos; Silva, Wander Gonçalves da; http://lattes.cnpq.br/4669127331497967; Cruz Junior, Gelson da; http://lattes.cnpq.br/4370555454162131; Cruz Junior, Gelson da; Silva, Wander Gonçalves da; Pickert, Volker; Oliveira, Marco Antonio Assfalk de; Cardoso, Alisson Assis
This work presents the use of different computational intelligence methods applied to the tuning of a set of PI controllers for a DC motor drive with speed and position control. For position control, three closed control loops are used: armature current, speed and position. For speed control, only the armature current and speed loops are considered. In both cases, the outputs of the PI armature current and speed regulators are limited to the rated armature voltage and current, respectively. Then, it is possible to use higher gains for the controllers, what makes the system to respond faster. However, the windup phenomenon can arise. To avoid it, anti-windup circuits are also used and therefore, the system becomes non-linear. Because of this, an optimum tuning of the controllers may become a difficult task. In order to explore different possibilities, firstly, the speed and position control problems are formulated so that only one objective is minimised. Within this single-objective optimisation context, the PSO and SA algorithms are used to tune the controller parameters, them, the capability of each one is investigated when compared to each other. Multiobjective formulations are also explored to address three objectives simultaneously. In this part of the work, the multi-objective evolutionary algorithms NSGA-II and SPEA2 are used. All algorithms were implemented in MATLAB and the electric drive models were developed in the SIMULINK environment. Simulation results are presented showing that for the single-objective formulation, for both, the for speed and position control problems, the PSO algorithm outperformed the SA. For the multi-objective formulation, the SPEA2 algorithm presented better characteristics with respect to the Spread quality indicator in the only, when compared to NSGA-II. Furthermore, it’s shown to outperform the NSGA-II with respect to the Hypervolume indicator within the position control problem. A series of tests were carried out by varying the values of the main parameters setting for each algorithm. However, in most cases, no statistically significant advantage was observed. In general, the results presented demonstrate the ability of the algorithms to find optimal tuning for the controllers, either for the single-objective or the multiple and conflicting objectives problem.
Algoritmos genéticos compactados para estimação de direção de chegada e conformação de feixe num arranjo de antenas em ambiente CDMA
(Universidade Federal de Goiás, 2015-07-06) Beltrán, Diego Fernando Burgos; Lemos, Rodrigo Pinto; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4790612H4; Lemos, Rodrigo Pinto; Menezes, Leonardo Rodrigues Araújo Xavier de; Vieira, Flávio Henrique Teles; Brito, Leonardo da Cunha
The continuous technological advances in the areas of electronics and programming made the signal processing techniques much easier to implement, allowing them to be incorporated in the communication systems, improving their performance. This work approaches the problem of estimating direction of arrival or angle of incidence (DOA) of electromagnetic wave fronts of a linear antenna array, and of beamforming of the array. Among the various techniques that exist in the literature, the Least Mean Squared algorithm (LMS) is a deterministic method that stands out for its simplicity, ease of implementation and the tendency to find local minima. On the other hand, the Genetic Algorithm (GA) is a heuristic method that ensures more comprehensive exploration possibilities avoiding the tendency of sticking to local minima, but offering greater difficulty of implementation, and higher computational complexity. The recently proposed Compact Genetic Algorithm (cGA) is a tool that shares all the virtues of GA, but without requiring the large computational cost that a GA entails. Since this method has not yet been used for controlling antenna arrays, this paper proposes to use it as the estimation of DOA and beamforming, in addition to enhance it with a number of modifications to make it more robust and more complete, though making it computationally heavier. This work presents simulations where the proposed adaptive receiver is evaluated under different scenarios of signal to noise ratio (SNR), number of interfering sources and convergence velocity. Moreover, moving users tracking situations are simulated, where the receiver's ability to adapt its radiation pattern is tested. All tests were done in the code division multiple access (CDMA) environment, where the only information available to the receiver are the sources spreading codes. To verify the operation of the cGA, its performance was compared with that of the LMS algorithm simulation under the same simulation conditions. The development of this thesis allowed to publish the articles named Adaptive Beamforming for Moving Targets Using Genetic Algorithms and a CDMA Reference Signal in the IEEE Colombian Conference on Communications and Computing COLCOM 2015, and Adaptive Beamforming for Moving Targets Using Genetic Algorithms in the IEEE Workshop on Engineering Applications WEA 2015 – International Congress on Engineering. The last one was accepted as an extended version to be publish in the magazine INGENIERÍA that belongs to the Distrital Francisco José de Caldas University in Bogotá, Colombia.
Alocação adaptativa de banda e controle de fluxos de tráfego de redes utilizando sistemas Fuzzy e modelagem multifractal
(Universidade Federal de Goiás, 2014-06-26) Cardoso, Alisson Assis; Vieira, Flávio Henrique Teles; http://lattes.cnpq.br/0920629723928382; Vieira, Flávio Henrique Teles; Carvalho, Cedric Luiz de; Brito, Leonardo da Cunha
Inthispaperweproposeafuzzymodel,calledFuzzyLMScomAutocorrela¸c˜aoMultifractal, whose weights are updated according to information from multifractal traﬃc modeling. These weights are calculated by incorporating an analytical expression for the autocorrelation function of a multifractal model in the training algorithm of the fuzzy model that is based on the Wiener-Hopf ﬁlter. We evaluate the prediction performance of the proposed network traﬃc prediction algorithm with respect to other predictors. Further, we propose a bandwidth allocation scheme for network traﬃc based on the fuzzy prediction algorithm. Comparisons with other bandwidth allocation schemes in terms of byte loss rate, link utilization, buﬀer occupancy and average queue size veriﬁes the eﬃciency of the proposed scheme. Also, We propose an other adaptive fuzzy algorithm, called Fuzzy-LMS-OBF com alfa adaptivo , for traﬃc ﬂow control described by theβMWM model. The proposed algorithm uses Orthonormal Basis Functions (OBF) and its training based on the LMS algorithm. We also present an expression for the optimal traﬃc source rate derived from Fuzzy LMS. Then, we evaluate the performance of the Fuzzy-LMS-OBF com alfa adaptivo algorithm with respect to other methods. Through simulations, we show that the proposed control scheme is beneﬁted from the superior performance of the proposed fuzzy algorithm. Comparisons with other methods in terms of mean and variance of the queue size in the buﬀer, Utilization rate of the link, Loss rate and Throughput are presented.
Alocacao de blocos de recurso em redes LTE e utilizando logica fuzzy e estimacao adaptativa de banda efetiva
(Universidade Federal de Goiás, 2015-03-19) Abrahao, Diego Cruz; Vieira, Flavio Henrique Teles; http://lattes.cnpq.br/0920629723928382; Vieira, Flavio Henrique Teles; Carvalho, Henrique Portela de; Deus Júnior, Getúlio Antero de; http://lattes.cnpq.br/8531659368461322
In this paper we propose two schemes for allocating resource blocks for transmission LTE downlink to maximize the throughput of the system, to guarantee QoS (Quality of Service) parameters for the users and reduce the data loss rate of network. The first proposed scheme uses the Max-min criterion and the second employs a fuzzy inference system to calculate the priorities of users and make scheduling decisions. Both schemes use an estimated effective bandwidth of traffic flows of users. The effective bandwidth of a traffic flow is the rate required to meet a criterion of probability of data loss rate. In this work, the effective bandwidth is estimated adaptively by the parameters of multifractal modeling βMWM (β-Multifractal Wavelet Mode). Are made simulations of the algorithms proposed, considering different propagation models with multipath fading and with different numbers of users in the network. The simulation results are compared with other algorithms presented in the literature, using parameters such as: throughput of the system, data loss rate and fairness index. It is also proposed to use predict of the SNR (Signal-to-Noise Ratio) of users, in the scheduling algorithms, using linear prediction of multi-step filter, in view of the delay in receipt of the channel quality information of the users in the base station and the variation of the signal propagation conditions. The multi-step prediction filter is used with the algorithms of allocation of resource blocks proposed in this work to estimate the signal-to-noise-ratio of users and set well, modulation schemes and code to be used in the LTE network.
Alocação de blocos de recursos em redes LTE utilizando estimativa de limitante de retardo através de cálculo de rede
(Universidade Federal de Goiás, 2015-12-11) Ferreira, Marcus Vinícius Gonzaga; Vieira, Flávio Henrique Teles; http://lattes.cnpq.br/0920629723928382; Vieira, Flávio Henrique Teles; Borges, Vinicius da Cunha Martins; Lemos, Rodrigo Pinto
In this work we propose an algorithm to allocate resource blocks for LTE (Long Term Evolution) communication systems that takes into account the maximum delay guarantee and MCS (Modulation and Coding Scheme) constraints on the downlink transmission. At first, we propose an allocation algorithm which tries to reduce user‘s delay using the information of the network real delay and the channel transmission quality. Next, we propose an allocation algorithm which considers the channel transmission quality and the delay target, which is estimated through Network Calculus using service curve and MFBAP (Multifractal Bounded Arrival Process) envelope process, in order to decide on the scheduling of available radio resources. Comparisons with other allocation algorithms are carried out through QoS (Quality of Service) parameters such as average delay, total throughput, loss rate, fairness and processing time, verifying the efficiency of the proposed algorithm.
Alocação de recursos em redes sem fio multiportadoras com ondas milimétricas utilizando aprendizado por reforço baseado em modelo Markoviano
(Universidade Federal de Goiás, 2022-07-08) Carneiro, Daniel Porto Queiroz; Cardoso, Alisson Assis; http://lattes.cnpq.br/8216536516894987; Vieira, Flávio Henrique Teles; http://lattes.cnpq.br/0920629723928382; Vieira, Flávio Henrique Teles; Soares, Anderson da Silva; Cardoso, Alisson Assis; Lemos, Rodrigo Pinto
In this dissertation, we present reinforcement learning-based resource allocation algorithms for a multicarrier communication system considering multiple users and the effects of multipath and average path loss in a transmission assuming millimeter waves. To this end, it is proposed that the communication system can be described by a Markovian model represented by queue states in buffers and channel states. For the resource allocation algorithms of this work, we introduce reward functions to be used in the reinforcement learning algorithm Q-learning. The results obtained in the simulations show that the application of the proposed algorithms for resource scheduling provides, in general, an improvement in the performance parameters of the considered communication system, such as, for example, increased throughput and decreased packet loss. Comparisons with other algorithms presented in the literature are carried out, also showing that the use of the proposed reward function and considered Markovian model makes the scheduling of users and the sharing of resources more efficient. Furthermore, a solution for resource and power allocation using a Deep Q-Network is presented. The modeling of states proposed for the DQN network covers some limitations encountered with the matrix representation of states and extends the limits for the size of the buffer.
Alocação de recursos em sistemas Internet das Coisas utilizando aprendizagem por reforço
(Universidade Federal de Goiás, 2021-08-04) Vasconcelos, Matheus Matos; Cardoso, Álisson Assis; http://lattes.cnpq.br/8216536516894987; Vieira, Flávio Henrique Teles; http://lattes.cnpq.br/0920629723928382; Vieira, Flávio Henrique Teles; Cardoso, Kleber Vieira; Rocha, Flávio Geraldo Coelho; Cardoso, Álisson Assis
This paper proposes a utilization of a reinforcement learning (RL) algorithm to control the packet transmission of multiple devices of a Cognitive Internet of Things (IoT) wireless communication system. The proposed approach consists of adopting a Markov chain to model the states of the communication system and its transitions, providing the required parameters to determine actions to the system using a Q-Learning algorithm. This paper also presents a performance evaluation of the developed algorithm in comparison to some scheduling algorithms in terms of: utility function, flow rate, buffer occupancy, packet loss rate, etc.
Alocação de taxa de transmissão utilizando predição do tráfego de rede baseada no expoente de Lyapunov e no parâmetro de Hurst
(Universidade Federal de Goiás, 2021-02-25) Rosa, Évelynn Regina da Costa; Rocha, Flávio Geraldo Coelho; http://lattes.cnpq.br/5583470206347446; Rocha, Flávio Geraldo Coelho; Vieira, Flávio Henrique Telles; Souza, Marcos Antonio de; Cardoso, Alisson Assis
This project describes a standard approach to analyze and measure experimental and synthetic data, which display linear and non-linear characteristics, within the spectrum of Chaos Theory and its canonical procedures, evaluating the performance of several algorithms. The main goal of this work is to propose a method to predict traffic and perform a dynamic traffic rate allocation for the network servers based on the Lyapunov exponent and the Hurst parameter, considering the analysis of a range of traffic samples and synthetic data, in order to quantify them with the use of mathematical methods that reveal their intrinsic features. Some of the characteristic processes described are self-similarity, long-range dependency among samples and multiscale behavior. Thus, it is necessary to: reconstruct phase space and the attractor with the ideal delay $\tau$, while describing a couple of methods to compute it; to determine embedding and correlation dimensions ($m$ and $D_2$, respectively); to calculate the Lyapunov exponent $\lambda$ and Hurst parameter $H$; to perform principal component analysis ($PCA$); to predict the traffic within the longest predictable duration constrained by the inverse of the Lyapunov exponent, and finally perform dynamic transmission rate allocation for the network servers. The simulations performed confirmed the efficiency of the proposed approach, regarding the sequence adopted in this work and the classification of data, especially in cases of mixed behavior between randomness and determinism.
Alocação e dimensionamento ótimo de geração distribuída utilizando o fluxo de potência intervalar
(Universidade Federal de Goiás, 2021-11-30) Nogueira, Wallisson Calixto; Garcés Negrete, Lina Paola; http://lattes.cnpq.br/3707701912481754; Garcés Negrete, Lina Paola; Brigatto, Gelson Antônio Andrea; Belati, Edmarcio Antonio
Modern Power Systems must deal with high levels of uncertainty in their planning and operation, these uncertainties are mainly due to variations in loads and distributed generation introduced by new technologies. This scenario brings new challenges for system planners and operators who need new tools to carry out more assertive analysis of the state of the network. This work presents an optimization methodology capable of considering uncertainties in the problem of sizing and sitting distributed generation in the networks. The proposed methodology uses the interval power flow (ILF) in order to add uncertainties to the combinatorial optimization problem that is solved through the meta-heuristics Symbiotic Organism Search (SOS) and Particle Swarm Optimization (PSO) for performance comparison purposes. The addition of uncertainties by ILF is validated by the probabilistic power flow (PLF) solved by Monte Carlo Simulation (MCS). This methodology was implemented in Python®, and was applied in the IEEE 33-bus, IEEE 34-bus and IEEE 69-bus test networks where distributed generation sizing and sitting problems were solved in order to minimize technical losses and to improve the voltage levels of the network. For the addition of uncertainties, the results obtained from the proposed ILF in the tested networks are compatible with those obtained by the PLF, thus showing the robustness and applicability of the proposed method. For the solution of the optimization problem, the SOS meta-heuristic proved to be robust, since it was able to find the best solutions that present the lowest losses, keeping the voltage levels regulated to the predetermined levels. On the other hand, the PSO meta-heuristic presents less satisfactory results, because for all the systems tested, the solution has a lower quality than that found by SOS, thus showing that the PSO algorithm presents difficulties to escape the minimum locations found during the simulation.
Alocação otimizada de dispositivos indicadores de faltas em linhas aéreas de distribuição utilizando busca em vizinhança variável
(Universidade Federal de Goiás, 2017-05-30) Vasconcelos, Jáder de Alencar; Alves, Antônio César Baleeiro; http://lattes.cnpq.br/1188328474646154; Alves, Antônio César Baleeiro; Morais, Flávio José de Oliveira; Brito, Leonardo da Cunha
Electricity distribution networks are constantly subject to contingencies that can lead to interruption of supply, bringing disruption to consumers of electric energy and increasing the cost of compensation for violation of individual indicators of continuity. In this context, Fault Indicator Devices (PIs) have been shown to be a promising alternative to improve Quality of Service. As the use of these equipments requires considerable investments, the use of IFs in arbitrary stretches of the network is prohibitive, making necessary the development of a methodology for the optimal allocation of these devices. In this sense, it is understood that a good methodology should minimize the average time of displacement of the maintenance teams to the locations of the defects, implying in the significant reduction of the other indicators dependent on this time, especially the Equivalent Duration of Interruption per Consumer Unit (DEC). The main contribution of this dissertation is the implementation of a meta-heuristic Variable Neighborhood Search (VNS), in order to determine the positions for the installation of the IFs, in order to reduce to the maximum the DEC estimation. In the methodology developed, the chosen network positions (sections) contemplate both the main trunk and the extensions, in addition to considering the influence of other protection devices in the network. In addition, the estimation of the average search time in the presence of these devices considers the failure rates and lengths of the stretches, extending the estimates made in other works. The results, obtained for a real feeder, in most of the studied situations, led to the allocation of IFs in sections of branches, bringing a more significant reduction in the Quality of Service indicators and demonstrating the effectiveness of the proposed methodology.
Ambiente virtual para reabilitação de membros superiores utilizando visão computacional
(Universidade Federal de Goiás, 2012-05-02) GOMIDE, Renato de Sousa; VIEIRA, Marcus Fraga; http://lattes.cnpq.br/4153462617460766
The use of computing devices used in virtual reality has been exploited to provide solutions in healthcare, specifically in functional rehabilitation. There are studies that indicate that immersion caused by the use of virtual environments in rehabilitation presents positive results on the evolution of a patient in therapy. From this information, there was motivation for this study, which aims at developing a low cost solution consisting in a virtual environment for upper limbs rehabilitation. This work describes the internal elements of the computing device and also the development of the virtual environment. The user interacts with the virtual environment through computer vision techniques, having a webcam as a data input device. Acquired images by the webcam are processed so that an object of interest may be in evidence by algorithms of image segmentation. There were analyzed five techniques of image segmentation in RGB and HSV color spaces. By the results obtained in the development environment, it wasn't possible to classify the best method of segmentation, and the performance of the methods varies according to the color of the object of interest and lighting of the external environment. The virtual environment was modeled after technical visits made in rehabilitation center supported by physiotherapists and occupational therapists. The virtual environment was tested only in research environment. Therefore it is necessary to employ the system in rehabilitation clinic in partnership with health professionals so that there is a validation of the virtual environment developed in this project in the area of rehabilitation.
Ambiente virtual utilizando o sensor kinect combinado com avaliação biomecânica para reabilitação dos membros superiores de pacientes acometidos de acidente vascular encefálico
(Universidade Federal de Goiás, 2015-06-23) Carvalhaes, Millys Fabrielle Araujo; Vieira, Marcus Fraga; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4772863U3; Vieira, Marcus Fraga; Nora, Fernanda Grazielle da SIlva; Vieira, Silvio Leão
This study proposes a computational tool to support motor rehabilitation of the upper limbs in post stroke patients. This tool was designed to be used in combination with Virtual Environment, which is also being developed at Bioengineering and Biomechanics Laboratory. Thereby, while the virtual environment focus is the patient interaction and immersion through Kinect Xbox 360 sensor, the main goal of this study is a biomechanical analysis of the movements performed by the patients via the data generated by the Kinect during the patient’s interaction with the virtual environment. Furthermore, since Kinect Xbox 360 is not designed for clinical analysis, tests were performed to compare the precision with respect to a standard motion capture system, the Vicon system, considered the gold standard, widely used in laboratories of biomechanics for kinematic analysis of movements. In this respect, statistical tests were used to compare the results of both systems. In addition, vector analysis using the Statistical Parametric Mapping method allowed provided about information about which coordinates had greater influence at the results.
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/4153462617460766
From 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.
Análise comparativa de métodos de otimização aplicados à sintonia do controlador PI
(Universidade Federal de Goiás, 2014-10-06) Reis, Márcio Rodrigues da Cunha; Calixo, Wesley Pacheco; http://lattes.cnpq.br/9073478192027867; Calixto, Wesley Pacheco; Viajante, Chunter Paulo; Marra, Enes Gonçalves; Silva, Wander Gonçalves da
This paper presents a comparative analysis of some methodologies for deterministic and heuristic optimization, applied to a classic problem in control theory. The aim is to determine the parameters tuning Proportional and Integral (PI) controller. The PI controller is used to control the speed of the DC motor. The mathematical model of the DC motor and the independent excitation of the AC-DC converter that is used in driving it is developed. From the mathematical model, the computational model is developed to perform the analysis of a commercial DC motor. In order to validate the computational model, a training bench is built, tests are performed and the results of the comparison between the methods of optimization are presented.

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