Programa de Pós-graduação em Engenharia Elétrica e da Computação

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Modelagem dos movimentos funcionais robótico-assistidos para a reabilitação dos membros superiores: redução dos graus de liberdade de um manipulador antropomórfico
(Universidade Federal de Goiás, 2010-04-19) ABADIA, Fernando Gonçalves; VIEIRA, Marcus Fraga; http://lattes.cnpq.br/4153462617460766
Rehabilitation robotics involves the development of active devices for various processes in the health field. In the rehabilitation case, it replace the physical assistance by a robotic device, under the supervision of the therapist. According to some authors, there is much evidence that repetitive movements can help in the rehabilitation of stroke patients. Therefore, there is feasibility of building a low cost robotic manipulator of an anthropomorphic arm with few degrees of freedom in the rehabilitation of patients in early brain injury phase (muscle hypotony phase). The objective of the study outlined here is to determine, through simulation, the appropriate kinematic of an anthropomorphic robotic manipulator that best approximate the functional movements to be relearned by stroke patients. The kinemetry was the method used to measure the characteristics of these movements. The data acquisition was performed from three subjects who performed the movements of combing hair, drinking from cup, bring it to his mouth and waving, greeting movement. These data were compared with the direct and inverse kinematics of the simulated manipulator in MatLab environment. The results showed that, despite the limitations of movements, the simulated manipulator is feasible for rehabilitation of patients who are in the initial phase of stroke, with a low cost of implementation.
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.
Aplicação de FPGA para controle de sistemas embarcados multiagentes: robôs jogadores de futebol da categoria IEEE very small size soccer
(Universidade Federal de Goiás, 2018-09-14) Aguas, Walisson Gobbo de; Silva, Karina Rocha Gomes da; http://lattes.cnpq.br/1198784669983966; Silva, Karina Rocha Gomes da; Lettinin, Djones Vinícius; Assfalk, Marco Antônio
The development of new technologies is mainly related to the construction of devices that aim in some way to assist the human being in his tasks, making them faster, easier and more precise. Since the discovery of the transistor, more than 70 years ago by John Bardeen and Walter Brattain, there has been a huge revolution, and new research areas have been created, especially in cooperative robotics and multi-agent. With the steady increase in the number of robots in an industrial environment, scientists and technologists have often faced problems of cooperation and coordination between different robots and their self-control in a workspace. This led to the evolution of autonomous multirobotic cooperative systems. Developers of multi-robotic autonomous systems needed a model to test the proposed theories in terms of effectiveness and efficiency. Not surprisingly, they began to focus on robot soccer. Robots soccer players have great demands in all areas of robot technology, mechanics, sensors and artificial intelligence. Thus, the objective of this work is to develop a small multi-agent system (7.5x7.5x7.5cm) intended to play soccer in a predetermined dynamic environment. A prototype will be developed for comparison purposes with a previously developed robot focusing on improvements to the multiagent controller system and the physical structure of the hardware.
Atenuação das componentes oscilantes de conjugado no gerador síncrono de polos salientes
(Universidade Federal de Goiás, 2018-08-30) Aleluia Junior, Leovir Cardoso; Alves, Aylton José; http://lattes.cnpq.br/2762752291082988; Calixto, Wesley Pacheco; http://lattes.cnpq.br/9073478192027867; Calixto, Wesley Pacheco; Alves, Aylton José; Pinheiro Neto, Daywes; Domingos, José Luiz; Oliveira, Marco Antônio Assfalk de
The present work is devoted to the development of a methodology for attenuation of the electromagnetic conjugate oscillations using insertion of AC components added to DC components in the field excitation of the synchronous generator of outgoing poles submitted to non-sinusoidal voltage conditions. It is used mathematical modeling able to consider the effects of harmonic components of current and voltage and study is carried out on the oscillations of conjugate using computational simulations. The synchronous generator is connected to the bus and subjected to sinusoidal and non-sinusoidal voltage conditions with the insertion of linear and non-linear loads. It is verified that the conjugate oscillations are influenced by the insertion of nonlinear loads, inducing the periodic behavior, being the main components of the sixth order and their multiple. The results obtained reduce the oscillating electromagnetic torque components by approximately 50%.
Descoberta automatizada de associações com o uso de algoritmo Apriori como técnica de mineração de dados
(Universidade Federal de Goiás, 2011-02-25) ALMEIDA, Derciley Cunha de; BRITO, Leonardo da Cunha; http://lattes.cnpq.br/6660680440182900
Nowadays, the use of modern information systems allows the storage and management of increasingly large amounts of data. On the other hand, the full analysis and the maximum extraction of useful information from this universe of available data present considerable challenges in view of inherent human limitations. This dissertation deals with the subject of data mining, which is the use of technology resources in order to extract information from databases in an automated way. One of the possibilities offered by data mining technologies is the automated search for possible associations within data. Information about such associations can be useful for understanding cause and effect relationships between the involved variables in data analysis for decision making. There are several data mining techniques and many of them can be used for discovering associations. The main goal of this work is to study a particular method for automated search of associations called Apriori , evaluating its capabilities and outcomes. The study focuses on the problem of improving the Apriori algorithm results, taking into consideration that the results of the data mining process might be improved if the data are prepared specifically for Apriori application. The conclusions are drawn from a case study in which the Apriori algorithm was applied to a database with information on drug distribution at a health institute. The results of two experiments are considered in order to evaluate the influence of data preprocessing on the Apriori algorithm's performance. It was found that the Apriori algorithm yields satisfactory results on the discovery of association in data; however, for best results, it is advisable that the data be prepared in advance, specifically for the Apriori application, otherwise many associations in the database might be left undiscovered.
Análise de metodologias para determinação da velocidade e atenuação acústica de materiais poliméricos por ultrassom pulso-eco
(Universidade Federal de Goiás, 2019-11-29) Almeida, Gilyane Oliveira Leão; Vieira, Sílvio Leão; http://lattes.cnpq.br/1254102050392862; Vieira, Ernanni Damião; Oliveira, Lucas Nonato de; Vieira, Sílvio Leão
Sound speed and attenuation coefficient are widely used in the definition of elastic constants, material characterization, differentiation between biological tissues, disease diagnosis, among others. However, due to the viscoelastic and dispersive characteristics, in many of these materials the phase velocity of the wave is not always equal to the group velocity. Thus, depending on the test methodology employed, the estimated values of these quantities change. Thus, the analysis of ultrasound tests can elucidate any existing divergences. Furthermore, the use of automated data acquisition and analysis methods can contribute to the reduction of measurement uncertainties and enable the evaluation of irregular samples. The precise characterization of these acoustic properties is extremely relevant for industry and medicine, as it contributes to the development of materials with better physical properties, as well as increasing diagnostic accuracy between healthy and abnormal tissues. In this work we analyzed pulse-echo ultrasound test methodologies for sound velocity determination and attenuation coefficient in agar-gel, paraffin oil and glycerin samples. Experiments were performed in an acrylic acoustic tank with water. The medium temperature was monitored using a thermocouple system. The ultrasound transducer was held perpendicular to a reflective plate at a greater distance than the near field. The data collection procedure took place in three stages, for each type of sample studied. First, only the properties of water were evaluated. Then a sample of (25.40±0,67) mm in thickness, and finally another of (50.80±0,67) mm. Agar-gel samples were used to validate the measurement system. A custom computational routine was developed and employed to acquire and process signals automatically. Pearson's linear correlation coefficient of 0.78 indicated a low chance that the water used as a reference medium would influence the results of the samples. The thickness obtained with caliper and ultrasound was compatible, whose value was 0.013. The relative percentage error of acoustic velocity with the literature ranged from 0.056% to 0.080%. The automation of the test methods showed a progressive improvement in the determination coefficient, reaching its maximum value of 0.99. The phase velocity method showed higher accuracy compared to the ones that evaluated the group velocity. The quantities obtained automatically had the lowest uncertainties.
Análise de desempenho de plataformas de educação a distância com arquitetura cliente-servidor utilizando teoria de filas
(Universidade Federal de Goiás, 2010-08-19) ALVES, Leonardo Antonio; VIEIRA, Flávio Henrique Teles; http://lattes.cnpq.br/0920629723928382
In this work, we present an analytical model to predict the performance of the client-server system regarding an E-Learning platform. This approach is based on the queuing theory and can adequately describe the performance of an E-Learning platform and its parameters, such as the server response time. It is used a Poisson model to describe the traffic processes in the EaD system, comparing the output of the model to an E-Learning platform working at the MSD Education company. In this study, it was developed a precise tool for designing E-Learning platforms based on client-server model according to the increasing access demand.
Aplicação da teoria da propagação do campo magnético na análise da máquina síncrona
(Universidade Federal de Goiás, 2020-06-17) Alves, Renato Silva; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Paula, Geyverson Teixeira de; Silva, Rui Vagner Rodrigues da
This work presents a methodology of analysis of the smooth poles synchronous machine in steady state using the theory of magnetic field propagation to obtain the V curve for a given active operating power and various operating factors. This theory is based on the division of the synchronous machine into layers and the application of Maxwell’s equations. This methodology is capable of considering magnetic saturation and the anisotropy of electric steel. The predefined current model is used to estimate the radial and tangential flow density of the layer. The results obtained are compared with the Park equations in steady state. For the validation of the methodology, it was a threephase synchronous four-pole smooth generator is used. The results obtained were very promising when compared to the Park equations on a permanent basis.
Estudo de geração fotovoltaica distribuída: análise econômica e o uso de redes neurais artificiais
(Universidade Federal de Goiás, 2017-03-09) Alves, Ricardo Henrique Fonseca; Deus Júnior, Getúlio Antero de; http://lattes.cnpq.br/8531659368461322; Lemos, Rodrigo Pinto; http://lattes.cnpq.br/3333000136853156; Lemos, Rodrigo Pinto; Deus Júnior, Getúlio Antero de; Cerqueira, Jês de Jesus Fiais; Castro, Marcelo Stehling de
The main goal of this work is to propose a methodology for the selection of 51 consumers in Nova Veneza-GO connected to two transformers in the pre-Smart Grid network. The methodology consists of ten stages ranging from the grouping of consumers with the same power consumption profile using a neural network, that is, a Non Parametric Self-Organizing Map (PSOM), until the complete and optimal allocation of financial resources through of an Integer Linear Programming. We obtained 12 different groups (clusters) of consumers of the two transformers with the same power consumption profile using the network PSOM algorithm. This grouping (clustering) was considered in the dimensioning and design of Photovoltaic Systems Connected to the Grid (Grid-Tie Systems) using three different computational tools, among them, an approach based on the PVSyst software, trial version V6.39. In addition, a study of Economic Engineering was carried out to expand the R&D pilot project aiming at the implementation of Grid Tie Systems for all the consumers of Nova Veneza-GO and Goiânia-GO, considering consumption data available by Celg-D and also considering two different scenarios based on the implementation of photovoltaic systems with and without government incentive. An Economic Engineering analysis was performed considering that 1%, 5%, 10%, 20%, 30% and 100% of Consumer Units (UC) adhere to the implantation of solar systems in Goiânia-GO. Environmental results were found for the city of Nova Veneza-GO and Goiânia-GO, evidencing an expressive reduction in CO2 emissions and a great saving of water.
Projeto e implementação de um piloto automático aplicado a aeromodelos de asa fixa e asa móvel
(Universidade Federal de Goiás, 2015-09-30) Alves, Rubens Antônio; Nerys, José Wilson Lima; http://lattes.cnpq.br/6816730643886734; Nerys, José Wilson Lima; http://lattes.cnpq.br/6816730643886734; Fleury, Cláudio Afonso; Marra, Enes Gonçalves
This Project, in the electrical engineering area, consists in the development of a complete control system, hardware and software, for controlling model airplanes of the fixedwing and rotary-wing types, aiming the implementation of an automatic control system compatible with the necessity of autonomous and aided flights, applied to critical systems monitoring.The final system consists of a controller, or automatic pilot, with specific hardware and software, capable of controlling a model airplane using GPS coordinates, in a way that allows the airplane to go through a planned route and go back to the starting point in an autonomous way. The controller should receive, in ground, the programmed route; the model should answer to the pilot commands, within a visual range when operating in the aided mode, and should go through the programmed route in the autonomous mode, after confirmation of the pilot. After reaching the end of the programmed route, the model airplane should return to the starting point, keeping the maximum flight level of the route as the reference height. The model airplane will carry in a communication system to allow the monitoring process from a ground station, able to keep updated the airworthy conditions, as well as the level of accuracy between the actual and the planned route. The communication may be carried out directly using a radio link, with the receiver allocated in a mobile ground station, monitored by a pilot, to make higher the security level. However, the model airplane may transfer the data through a GPRS link, connected to the web system, which transfers the data to the ground station. In this case, the ground station must be connected to the web.The route saved in the model control system is built based on online maps directly linked by the software for the mission programming and monitoring, which can carry out the treatment and storage of the model data and parameters. The programming of the stability control and route, with primary data of latitude, longitude and height allows the real time monitoring of the model, related to the planned route and throught images captured by embedded video cameras. All data are storage following a timeline process, such that they can be recovered for futher analysis.
Desempenho de métodos clássicos e meta-heurísticas aplicadas à sintonia de controladores PID sob o aspecto do fator de incontrolabilidade
(Universidade Federal de Goiás, 2023-03-30) Andrade Filho, Alfredo de Paulo; Cardoso, Alisson Assis; http://lattes.cnpq.br/8216536516894987; Cruz Júnior, Gelson da; http://lattes.cnpq.br/4370555454162131; Cruz Júnior, Gelson da; Avelar, Henrique José; Teixeira, Edilberto Pereira
The PID (Proportional Integral Derivative) is one of the most used in industry, and has been employed around the world for decades in industrial control systems. Its popularity can be attributed in part, to its robust performance, in a wide range of operating conditions, and their functional simplicity, which allows engineers to operate them in a simple and direct way. However, tuning such controllers effectively, represents a challenge to control engineers, since it directly affects the efficiency of the system. In the context of modern industry, the setback is even greater, due to the complexity of the processes involved, in which the presence of the Dead Time and the Time Constant of the system, have a great impact on its response. Tuning of PID controllers aims to satisfy some specifications imposed on the transient and steadystate characteristics of the response of the system being controlled. Generally, these specifications fall on the values of Rise Time (Tr), Settlement Time (Ts), Maximum Value overshoot (Mp) and a maximum acceptable Stationary Error (Ess) value. Within the scope of control problems that offer great complexity, either because of the impossibility of previously knowing the transfer function of the system, or due to its multivariable characteristics, several researches have been carried out within the scope of optimizing the tuning of PID controllers using meta-heuristics. In many situations, the system PID cannot be accurately modeled, and still malfunctions in the presence of noise or external disturbances due to the adjustment problem of its parameters that are challenging in practice, as they depend on characteristics of the environment. In this work, we sought to evaluate the performance of the PID controller under the aspect of Uncontrollability Factor when tuned by Genetic Algorithm heuristics (GA) and Particle Swarm (PSO), which have been shown to be more effective in compared to classical tuning methods. Six case studies were evaluated, with varied Uncontrollability Factors.
Aplicação de técnicas SPWM na segmentação dos polos da máquina síncrona de ímãs permanentes para redução na ondulação do torque
(Universidade Federal de Goiás, 2020-08-20) Andrade Júnior, Khristian Marques de; Paula, Geyverson Teixeira de; http://lattes.cnpq.br/0140145167826333; Paula, Geyverson Teixeira de; Alvarenga, Bernardo Pinheiro de; Silva, Wander Gonçalves da
In the present work, six methods are proposed considering the application of PWM techniques in the pole segmentation of permanent magnet synchronous machines in order to reduce the value of the torque ripple. Such methods reduce this ripple by eliminating the back-emf low-order harmonics and reducing the amplitude of the cogging torque. The PWM techniques considered here are the unipolar sinusoidal, bipolar, trapezoidal and sinusoidal with harmonic injection. A finite element analysis of the designed machines, under no load and under load conditions, is carried out in order to validate the presented methods. Method 1 presents the best results when the amplitude modulation index was kept constant and with unit value, guaranteeing a reduction in the cogging torque of 78.54%, however also reducing the electromagnetic torque by 17.87%. The major disadvantage of Methods 2, 5 and 6 is the presence of low order harmonics in their back-emf. The effect of using fractional-pitch winding is evaluated when these methods are considered to surpass the mentioned problem, however it is observed that, contrary to what is desired, the the torque ripple increases, while its average value reduces. Furthermore, the elimination of segments with width of less than 5◦ results, in general, in an increase of the back-emf harmonics and a behavior of the cogging torque without an apparent trivial pattern. Finally, an optimization process is carried out for Methods 1, 5 and 6, as these present the best results, to determine the optimal values of the amplitude and frequency modulation indices that guarantee a reduction in the cogging torque and mitigate the depreciation in the machine torque. In this scenario, Method 6 has the best results, reducing the torque ripple by about 88.02%, and increasing the fundamental density of the air gap flux by 4.55% in relation to that one of the reference machine.
Desenvolvimento de um sistema de termometria por ultrassom para monitoramento de temperatura
(Universidade Federal de Goiás, 2017-05-05) Andrade, Patrícia Cardoso de; Vieira, Sílvio Leão; http://lattes.cnpq.br/1254102050392862; Carneiro, Antônio Adilton Oliveira; Oliveira, Lucas Nonato de
Measuring internal temperature and/or temperature gradient in materials is of fundamental interest in both engineering and basic sciences because the temperature is closely related to the properties of the material. The purpose of this study was to develop an ultrasound thermometry system for internal temperature gradient monitoring of materials subjected to a heat source. A low cost oscilloscope was used as a system for the acquisition of ultrasonic signals. Jointly, was developed a computational algorithm responsible for estimating the internal temperature distribution of materials. For this purpose was used a low cost oscilloscope as a system for the acquisition of ultrasonic signals. Measurements were taken during the heating and cooling regimen of an aluminum block. A thermocouple temperature measurement system was used to verify and validate the temperature distribution obtained by the ultrasound thermometry method. The development of the computational algorithm responsible for communication and data collection provided real-time temperature measurements. The comparison of the temperature measurements derived from both methods showed agreement greater than 96%, with differences lower than 0.70°C. The methodology presented was relevant within the laboratory context to estimate the internal temperature of heated materials.
Aplicação da otimização por enxame de partículas com topologia "multi-ring" na estimação de parâmetros de linhas de transmissão
(Universidade Federal de Goiás, 2015-11-03) Arruda, Sérgio Alexandre Martins; Calixto, Wesley Pacheco; http://lattes.cnpq.br/9073478192027867; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Alvarenga, Bernardo Pinheiro de; Martins, Alessandro; Garcés Negrete, Lina Paola
Present world demands high availability of electricity for various equipment, in a context in which dominates the intensive use of technology. The electricity is transported from generation centers to consumers through Transmission Lines (TLs), which in Brazil have significant dimensions, given the continental size of the country, his predominantly hydro power plant generation, located long distances from major centers consumption. To ensure compliance of this high demand, often the electric power companies overload these TLs, generating undesirable effects, such as the formation of arrow in the conductors, for example. Monitoring of TL operating conditions is key part, therefore, to ensure system availability and security. This work aims in this context to present a method to assist in the monitoring of three-phase TLs of simple circuit based on measurement of electric and magnetic fields of the line and in application of an optimization procedure based on Particle Swarm Optimization metaheuristic, with a topology denominated Multi-Ring, to estimate simultaneously the values of current, voltage, cable-ground clearance of conductors and distance between phases, in a cross section of the line, assisting electric power companies and the National Electric System Operator (ONS) in the monitoring task. The good results achieved, combined with its simplicity of implementation compared to other methods and its robustness, indicate their suitability for estimating these parameters. Associated with this, the reasonably low times obtained in the execution make it promising for use by the electric power company and by the system operator as an auxiliary tool in monitoring TLs.
Cálculo do cogging torque em carga nas máquinas síncronas de ímãs permanentes no rotor
(Universidade Federal de Goiás, 2018-12-07) Assis, Lucas Franco de; Alvarenga, Bernardo Pinheiro de; http://lattes.cnpq.br/9850449311607643; Paula, Geyverson Teixeira de; http://lattes.cnpq.br/0140145167826333; Paula, Geyverson Teixeira de; Alvarenga, Bernardo Pinheiro de; Almeida, Thales Eugênio Portes de
This work investigates the different strategies of on-load cogging torque calculation in permanent magnet synchronous machine (PMSM) with the aid of the Finite Element Method along with the Frozen Permeability Method. Numerous researches have been carried throughout the years in order to accomplish the task of segregating the torque components and figure out the origins of torque oscillations. However, most of them have failed as they usually attribute the torque ripple only to the cogging torque and taking general conclusions based only in one type of PMSM. Here, in the present text, the investigation is carried out comparing the most cited and recent methods of on-load cogging torque assessment taking into account the electromagnetic saturation in different PMSM topologies. The results and discussion show that the most suitable methodology is not based on electromagnetic energy neither based on the electromagnetic coenergy but based on flux distribution.
Utilização de um sistema de realidade virtual não imersiva como ferramenta para a reabilitação de membros superiores de indivíduos hemiparéticos
(Universidade Federal de Goiás, 2008-09-05) BARBOSA, Dagoberto Miranda; OLIVEIRA, Marco Antonio Assfalk de; http://lattes.cnpq.br/5601509957082902; SANTOS, Euler Bueno dos; http://lattes.cnpq.br/5005722083309404
Metodologia de otimização de lentes para lâmpadas de LED
(Universidade Federal de Goiás, 2013-06-14) Barbosa, José Luiz Ferraz; Brito, Leonardo da Cunha; Calixto, Wesley Pacheco; http://lattes.cnpq.br/9073478192027867; Calixto, Wesley Pacheco; Brito, Leonardo da Cunha; Yamanaka, Keiji; Alves, Aylton José; Marra, Enes Gonçalves
The purpose of this work is to present a methodology for optimizing the geometry of the Light Emitting Diode (LED) secondary lens, in non-imaging applications, which focuses on the distribution of illuminance on a target plane. The simulation of Ray Tracing is produced by stochastic method and the optimization process based on heuristic search interacts with Ray Tracing to nd the optimized parameters of the LED secondary lens geometry.
Controle postural de idosos em superfícies inclinadas: descritores clássicos e modernos
(Universidade Federal de Goiás, 2014-11-28) Barbosa, Renata da Costa; Vieira, Marcus Fraga; http://lattes.cnpq.br/4153462617460766; Vieira, Marcus Fraga; Oliveira, Leandro Luís Galdino de; Nora, Fernanda Graziele da Silva Azevedo
Understanding how the postural control system is impaired with aging can help identify elderly at risk of falling. In order to study the postural control, center of pressure (CP) behavior can be analyzed. Classical descriptors are commonly used for the CP analysis, however, modern descriptors have been developed aiming to provide more information about the underlying processes involved in the postural control. Aims: Analyze and compare classical and modern descriptors used to analyze the postural control in elderly subjects in quiet standing posture, using data acquired from a force platform in horizontal and inclined surfaces. Methods: The study sample consisted of 17 elderly subjects who remained on a force platform in the upright posture for 70 seconds. The data acquisition was performed with the platform on a horizontal surface and again on a surface inclined at 14 degrees with dorsiflexion and later with plantar flexion of the ankle. For each slope, the procedure was repeated three times with eyes open (EO ) and three times with eyes closed (EC). The initial 10 seconds were discarded and then, CP times series were analyzed in the anteroposterior (AP) and mediolateral (ML) directions. The classical descriptors used were in the time in the frequency domain and the modern descriptors were: Detrended Fluctuations Analysis (DFA), Stabilogram Diffusion Analysis (SDA) and the Sway Density Curve (SDC). Results: In the classical analysis, the results showed significant differences in all comparisons made and, in the modern analysis, the variables provided by the SDA and SDC also showed significant differences between comparisons, however, the DFA did not provide any difference between the conditions. Conclusion: Results provided by the classical variables and by the SDA and the SDC suggest a lower stability of elderly subjects in the inclined surface with dorsiflexion followed by plantar flexion and the eyes closed condition. More studies with the modern descriptors are necessary to better understand their results.
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.
Avaliação de características e previsão de sucesso de canções populares brasileiras por meio de aprendizado de máquina
(Universidade Federal de Goiás, 2021-04-13) Bertoni, André Augusto; Lemos, Rodrigo Pinto; http://lattes.cnpq.br/3333000136853156; Lemos, Rodrigo Pinto; Vieira, Flávio Henrique Teles; Calixto, Wesley Pacheco; Almeida, Anselmo Guerra de
This work aims to develop algorithms capable of predicting whether a Brazilian popular song can become a commercial success, using the help of Machine Learning techniques. To achieve this goal, a bank of popular Brazilian songs performed on the radio from 2014 to 2019 was created, applying the number of radio plays as the criterion for separating the songs into a successful group and another of non-successful. Several techniques of Data Analysis were studied and applied to optimize the databases and extract statistical characteristics of the songs. From the study of music theory, a set of musical semantic characteristics extracted from each song was also defined to support the Machine Learning algorithms, and then employ Data Science techniques to predict if a song can become a commercial success. Classification algorithms with supervised training were used, both by the classical approach and by means of Deep Neural Networks. For training and validation, cross-validation was used with ten subsets for the classical approach, and five subsets for convolutional networks. The performance of the algorithms was compared basically in terms of accuracy, precision, sensitivity and specificity. The discussion of the results of this work showed that statistical characteristics extracted from the songs brought satisfactory results in several metrics, such as: Accuracy (69.63%), Precision: (69.03%), Sensitivity (71.55%), Balanced Accuracy (69.75%) and ROC (69.75%), using classic techniques as: Naive Bayes, Decision Tree, Random Forest, kNN, Logistic Regression, SVM and MLP - which represents an excellent result, when compared to several other works of literature. Deep Neural Networks of the Convolutional type did not bring good results, with little better accuracy than randomness. The best scenario was achieved by combining three distinct banks of characteristics: a) statistics; b) spectrographs extracted from the Main Voice Melody; c) Musical Melodic Semantic information. With the combination of these three distinct banks of characteristics, 74.54% Accuracy was obtained.

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