Doutorado em Engenharia Elétrica e da Computação (EMC)

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Navegando Doutorado em Engenharia Elétrica e da Computação (EMC) por Por Área do CNPQ "ENGENHARIAS::ENGENHARIA ELETRICA"

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    Localização em ambiente interno usando a rede celular
    (Universidade Federal de Goiás, 2024-07-15) Conceição, Paulo Francisco da; Rocha, Flávio Geraldo Coelho; http://lattes.cnpq.br/5583470206347446; Rocha, Flávio Geraldo Coelho; Vieira, Robson Domingos; Silva, Hugo Vinícius Leão e; Lemos, Rodrigo Pinto; Vieira, Flávio Henrique Teles
    In this work, we propose an approach for Simultaneous Localization and Mapping (SLAM) of the Mobile Station (MS) and scatterers (SCs) in indoor environments using the cellular network. The approach, named IndoorLoc, employs a Single bounce scattering model and treats signals as rays, representing each radio frequency signal originating from multiple paths in an indoor environment where reflections occur at SCs. The estimation of the MS and SCs positions involves three main stages: (1) channel modeling, employing millimeter waves (mmWave) and a massive number of antennas (massive MIMO - mMIMO) arranged in a rectangular array; (2) parameter estimation, using an adaptive method based on Compressed Sensing (CS), the Distributed Compressed Sensing Simultaneous Orthogonal Matching Pursuit (DCS-SOMP); and (3) localization of the MS and SCs, applying geometric methods to detect Line of Sight (LoS) and Non-Line of Sight (NLoS) conditions and specific algorithms for each of these conditions. For IndoorLoc, two geometric methods are proposed: one for LoS conditions, which uses Time of Arrival (ToA) and Angle of Departure (AoD) parameters to determine the direction of propagation and the distance between the BS and the MS, and another for NLoS conditions, which uses ToA, AoD, and Angle of Arrival (AoA) to determine intersection points of the trajectories. This intersection point serves as the initial estimate of the MS localization and acts as an input for further refinement using a Gauss-Newton-based estimator, which minimizes the localization error using a nonlinear model derived from the ToA, AoD, and AoA parameters. The performance of the localization algorithms is evaluated through comparisons of the Root Mean Square Error (RMSE) values with existing methods in the literature. Additionally, simulations were conducted in an indoor environment configured according to the specifications of the 3rd Generation Partnership Project (3GPP). The results demonstrate that the accuracy of IndoorLoc meets the standards of the Federal Communications Commission (FCC) and 3GPP.
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    Extensão da Transformada dq para Máquina Síncrona de Imãs Permanentes Não Senoidal com Corrente de Sequência Zero
    (Universidade Federal de Goiás, 2025-01-30) Lemes Filho, Celio Corrêa; Paula, Geyverson Teixeira de; http://lattes.cnpq.br/0140145167826333; Paula, Geyverson Teixeira de; Alvarenga, Bernardo Pinheiro de; Pereira, William César de Andrade; Monteiro, José Roberto Boffino de Almeida; Paula, Marcelo Vinícius de
    This work proposes a novel generalized extension of the Park transformation (dq), which facilitates the control of permanent magnet synchronous machines with open-end winding or Y-connected machines with an accessible neutral, where the back electromotive force (BEMF) waveform is non-sinusoidal. The proposed transformation, called dqy, enables the utilization of all harmonic components present in the back electromotive force for electromagnetic torque production. The proposed extension is applied to a permanent magnet synchronous machine through a magnitude amplification coefficient and a rotation angle. The new coordinate system allows for the reduction of power losses in the stator winding, as all current flowing through the machine contributes to the production of electromagnetic torque. The results obtained through simulation and experimental testing validate the effectiveness of the proposed vector control
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    Controle de potência reativa para adequação de valores de tensão e redução de perdas em redes elétricas com geração distribuída fotovoltaica
    (Universidade Federal de Goiás, 2024-05-06) Lopes Filho, Gilberto; Vieira, Flávio Henrique Teles; http://lattes.cnpq.br/0920629723928382; Vieira, Flávio Henrique Teles; Negrete, Lina Paola Garces; Corrêa, Henrique Pires; Franco, Ricardo Augusto Pereira; Souza, Gustavo Souto de Sá e
    This work presents contributions aimed at improving the electrical voltage profile in compliance with regulatory standards and reducing or minimizing losses in a radial electrical network with distributed photovoltaic generation. By injecting reactive power in a controlled manner through inverters connecting their respective photovoltaic generators to the distribution network buses, it is possible to control network voltages and losses. This work proposes three distinct approaches. The first algorithm, based on observations of the electrical network’s behavior, determines generated reactive power values capable of reducing electrical losses and regulating voltage for various levels of distributed generation penetration and load power factor. The allocation of photovoltaic generators and power values is randomly generated, and through a Monte Carlo simulation, the performance of the proposal can be analyzed. The second proposal uses heuristic algorithms (Genetic Algorithm and Firefly Algorithm) to estimate optimal reactive power values at the buses, aiming at voltage regulation, minimization of electrical losses, or minimization of losses with constraints on voltage magnitude values. The third proposal employs analytical relationships between reactive power, power loss, and voltage deviation to control reactive power injections into the electrical network. These analytical relationships, derived from the equations in this work, ensure computational simplicity while optimizing loss reduction and voltage deviation. This proposal includes the Loss Reduction Algorithm (LRA) and the Voltage Regulation Algorithm (VRA) and introduces an approach to efficiently switch between them called the Combined Control Strategy (CCS). The CCS seeks to provide a balance between voltage regulation and the reduction of electrical losses. Computational simulations are conducted to validate and analyze the performance of each proposal, varying various parameters of the algorithms and the network. All such Proposals are compared with other methods described in the literature, highlighting the superiority of the contributions presented in this work
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    Aplicação da transformada de Hilbert-Huang e da seleção paraconsistente de características no campo da entomologia agrícola: uma abordagem para identificação e estimativa de densidade de cigarras em lavouras cafeeiras
    (Universidade Federal de Goiás, 2023-12-01) Souza, Uender Barbosa de; Escola, João Paulo Lemos; http://lattes.cnpq.br/5894769490673984; Brito, Leonardo da Cunha; http://lattes.cnpq.br/6660680440182900; Brito, Leonardo da Cunha; Vieira, Flávio Henrique Teles; Lemos, Rodrigo Pinto; Escola, João Paulo Lemos; Maccagnan, Douglas Henrique Bottura
    The sounds emitted by various insect species carry specific and reliable acoustic characteristics. For this reason, acoustic identification of insects has been widely investigated by the scientific community in the field of pattern recognition. In Brazil, the cicada species Quesada gigas is considered a pest in coffee crops due to its sap-feeding habits, which can cause losses to farmers during intense attacks. Given this scenario, and considering the fact that the most striking characteristic of cicadas is sound emission for reproductive purposes, this work proposes a system designed to assist in the management of pest insects in coffee crops. Specifically, this system aims to detect the presence of cicadas or estimate their density through acoustic signals. The approach innovatively combines the extraction and analysis/selection of sound features through the Hilbert-Huang Transform (HHT) and Paraconsistent Feature Engineering, two emerging methods of growing interest in the scientific community. A detailed study was conducted on the influence of eight stopping criteria for the Empirical Mode Decomposition, the first step of HHT, considering variations of parameters, temporality, signal sampling, and also the encoding of these signals in two formats. The first defines vectors by the energies of the Intrinsic Mode Functions (IMFs) in order of extraction, while the second distributes the energies of the IMFs according to the 25 frequency bands of the Bark Scale. Additionally, the dimensional variation of the vectors was analyzed. The experiments allowed determining low computational cost configurations, showcasing the efficacy of the proposed system, with models based on Support Vector Machines achieving accuracies above 98% in both identification and density estimation of cicadas. Thus, this document details the theoretical foundations, design, development of the system, discussions about possibilities for its practical application, and an initial analysis of a developed application for smartphones. This proposal has the potential to encourage the reuse of old electronic equipment, promoting sustainable and economically viable practices.