PROGRAMA DE PÓS GRADUAÇÃO EM ENGENHARIA DE ELETRICIDADE - PPGEE

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    Classificação de Fibrilação Atrial utilizando Curtose
    (Universidade Federal do Maranhão, 2017-02-16) OLIVEIRA jÚNIOR, Alfredo Costa; BARROS FILHO, Allan Kardec Duailibe; 340225893-53; http://lattes.cnpq.br/0492330410079141
    Atrial fibrilation(AF) is one of the most common cardiac arrhythmias worldwide. Thus, there are ample efforts to implement AF diagnosis systems. The main noninvasive way to assess cardiac health is through electrocardiogram (ECG) signal analysis, which represents the electrical activity of the cardiac muscle, and has characteristic temporal markings: P, Q, R, S and T waves. Some authors use filtering techniques, statistical analysis and even neural networks for detecting AF based on the RR interval, that is given by the temporal difference between the peaks of the R wave. However, analises of the RR interval allows for evaluating changes occurring only in the R wave of the ECG signal, not allowing to assess, for example, variations in the P wave provoked by the AF. In face of that, we propose characterize the ECG signal amplitude aiming at classifying both healthy and AF patients. The ECG signal was analyzed in the proposed methodology through the following statistics: variance, asymmetry, and kurtosis. Herein, we use the MIT-BIH Atrial Fibrillation and MIT-BIH Normal Sinus Rhythm database signals to evaluate AF and normal heartbeat intervals. Our study shown that kurtosis outperfomed variance and asymmetry with respect to sensibility (Se = 100%), specificity (Sp = 88.33%) and accuracy (Ac = 91.33%). The results were expected since kurtosis is a non-Gaussian measure and the ECG signal has sparse distribution. The proposed methodology also requires a lower number of pre-processing stages, and its simplicity allows for implementations in imbedded systems supporting the clinical diagnosis.
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    Desenvolvimento de um chaveador baseado em topologia spdt associado a sensores interdigitados para medicao de parametros de capacitancia e impedancia em misturas pseudobinarias diesel/biodiesel
    (Universidade Federal do Maranhão, 2019-04-11) ANDRADE, Cassio Daniel Salomao Silva; MENDES, Francisco Savio; 008865174-60; http://lattes.cnpq.br/5984945942545807; BARROS FILHO, Allan Kardec Duailibe; 340225893-53; http://lattes.cnpq.br/0492330410079141; BARROS FILHO, Allan Kardec Duailibe; 927999733-53; http://lattes.cnpq.br/0492330410079141; MENDES, Francisco Savio; 008865174-60; http://lattes.cnpq.br/5984945942545807; RIBEIRO, Aurea Celeste da Costa; lattes.cnpq.br/7281004775553558; CASAS, Vicente Leonardo Paucar; http://lattes.cnpq.br/1155686983267102; NETO, Joao Viana da Fonseca; http://lattes.cnpq.br/0029055473709795
    The increasing addition of biodiesel to diesel has reached significant market importance and methods for detecting these levels, in these blends, have been essential in the monitoring of their quality. In this context, it is proposed the design, construction and evaluation of an 8- channel microcontrolled switcher based on miniature electromechanical armature relays that, in association with an LCR meter, allows the measurement of capacitance and impedance parameters in multiple diesel/biodiesel blend samples, using, for this purpose, an interdigitated electrode to investigate the feasibility of multiple measurements of these parameters and to evaluate the applicability of this methodology in the detection of biodiesel contents in those samples. A functional test to determine the mean percentage errors and measurement uncertainties associated with each switcher channel, relatively to reference values – obtained with an ordinary capacitor directly connected to the LCR bridge terminals –, as well as a significance test to evaluate the differences between the the measured values with and without interposing switcher were performed. It is suggested, subsequently, an apparatus for detection of organoleptic patterns in substances (electronic tongue/nose), electrochemical and/or biochemical (electronic probing device).