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Your search keyword '"Almeida, Pedro"' showing total 155 results
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155 results on '"Almeida, Pedro"'

6. Hands Tech: An AR-Based Framework for Real-Time Monitoring and its Application in 4.0 Industry

Author

De Maria Calado Machado Soares, Lívia, primary, Silva De Almeida, Pedro Henrique, additional, Pereira Santos, Lilian Giselly, additional, Freitas Ferreira Cavalcante, Mário Sérgio, additional, De Araújo Tiburtino Neves, Tácito Trindade, additional, De Lima Torres, Winnie, additional, De Medeiros Martins, Allan, additional, and Queiroz de Araújo, Ícaro Bezerra, additional

Published
2023
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17. Frequency-Based Active Ripple Compensation Technique to Reduce Bulk Capacitance in Integrated Offline LED Drivers.

Author

Ferraz, Ruan M., Resende, Lucas H. G., Braga, Henrique A. C., Almeida, Pedro S., Alonso, J. Marcos, and Soares, Guilherme M.

Subjects
LIGHT emitting diodes, POWER density
Abstract

In order to increase the power density and the lifespan of light-emitting diodes (LED) drivers, several studies have proposed active ripple compensation (ARC) techniques for minimizing the converter bulk capacitance. However, a common side effect of the ARC method is the increase in the total harmonic distortion (THD) of the converter input current. In this context, a frequency-based ARC technique is proposed as an alternative to the conventional ARC methodology, in which the duty cycle is modulated. The analyses presented in this article show that the frequency-based ARC approach applied to resonant converters has a better performance than the one used in hard-switching converters, since it allows for a huge capacitance reduction with a small THD increase. Furthermore, this article presents a generalized analysis of ARC techniques applied to integrated offline LED drivers, which reduce the number of components and the overall LED driver cost. The input current harmonic content and the output ripple reduction have been theoretically predicted for several converters. Experimental results gathered from a 96-W laboratory prototype supplied from a 127-V 60-Hz grid attested the superior performance of the frequency-based active ripple compensation, since a capacitance reduction of 66.6% has been obtained with an increase of only 0.9% in the THD. [ABSTRACT FROM AUTHOR]

Published
2022
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18. Multivariable Optimal Control Applied to a Back-to-Back Power Converter.

Author

Souza, Igor D. N., Almeida, Pedro Machado de, Fogli, Gabriel A., Barbosa, Pedro Gomes, and Ribeiro, Paulo Fernando

Subjects
*SINGULAR value decomposition, *TRACKING control systems, *REACTIVE power
Abstract

This article proposes the analysis and control design of back-to-back (BTB) converter using multivariable approach. Singular value decomposition and relative gain array are used to analyze the BTB converter as a multiple-input multiple-output system and decide which variables should be controlled in a given frequency range. Based on the aforementioned analysis, a suitable low- and high-frequency controllers are included in order to asymptotically track the references and reject disturbances. A systematic approach, analyzing the sensitivity and complementary sensitivity functions, is carried out to tune a centralized optimal linear quadratic multivariable control. Experimental results are presented to validate the analysis and control design. [ABSTRACT FROM AUTHOR]

Published
2022
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31. Scaling the assessment of emotion regulation effectiveness with a low-cost psychophysiological system

Author

Moreira, Pedro Miguel Silva, Chaves, Pedro, Almeida, Pedro R., Dias, N. S., and Universidade do Minho

Subjects
Electrodermal activity, Science & Technology, Emotion regulation, Ciências Médicas::Medicina Básica, Psychophysiology
Abstract

In this work, we assessed the reliability of a low-cost psychophysiological system - the James One device - to monitor the electrodermal activity during an emotion induction paradigm. We observed that during emotional expression in response to negative stimuli, participants displayed increased amplitudes of the skin conductance responses, in comparison to the natural observation of neutral pictures and to emotion regulation. These results are in accordance with previous findings obtained with medical-grade devices. Altogether, these results highlight the potential of this system to be implemented in large-scale settings, particularly in psychopathological conditions marked by severely impaired emotion regulation ability, such as depression and anxiety., (undefined)

Published
2019

41. Computational and Experimental Study of Time-Averaged Characteristics of Positive and Negative DC Corona Discharges in Point-Plane Gaps in Atmospheric Air.

Author

Ferreira, Nuno G. C., Almeida, Pedro G. C., Benilov, Mikhail S., Panarin, Victor A., Skakun, Victor S., Tarasenko, Victor F., and Naidis, George V.

Subjects
*CORONA discharge, *GLOW discharges, *CURRENT-voltage characteristics, *RADIATION, *VOLTAGE control
Abstract

The use of stationary solvers instead of approximate solution methods or time-dependent solvers, which are standard tools in gas discharge modeling, allows one to develop a very fast and robust numerical model for studying the time-averaged characteristics of dc corona discharges. Such an approach is applied to dc corona discharges in point-plane gaps in ambient air. A wide range of currents of both voltage polarities and various gap lengths are investigated, and the simulation results are validated by comparing the computed current–voltage characteristics and spatial distributions of the radiation intensity with experimental results. Specific features of the numerical and experimental results at both polarities are discussed. [ABSTRACT FROM AUTHOR]

Published
2020
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42. An Enhanced Visualization of DBT Imaging Using Blind Deconvolution and Total Variation Minimization Regularization.

Author

Mota, Ana M., Clarkson, Matthew J., Almeida, Pedro, and Matela, Nuno

Subjects
DECONVOLUTION (Mathematics), SIGNAL-to-noise ratio, TOMOSYNTHESIS, VISUALIZATION
Abstract

Digital Breast Tomosynthesis (DBT) presents out-of-plane artifacts caused by features of high intensity. Given observed data and knowledge about the point spread function (PSF), deconvolution techniques recover data from a blurred version. However, a correct PSF is difficult to achieve and these methods amplify noise. When no information is available about the PSF, blind deconvolution can be used. Additionally, Total Variation (TV) minimization algorithms have achieved great success due to its virtue of preserving edges while reducing image noise. This work presents a novel approach in DBT through the study of out-of-plane artifacts using blind deconvolution and noise regularization based on TV minimization. Gradient information was also included. The methodology was tested using real phantom data and one clinical data set. The results were investigated using conventional 2D slice-by-slice visualization and 3D volume rendering. For the 2D analysis, the artifact spread function (ASF) and Full Width at Half Maximum (FWHMMASF) of the ASF were considered. The 3D quantitative analysis was based on the FWHM of disks profiles at 90°, noise and signal to noise ratio (SNR) at 0° and 90°. A marked visual decrease of the artifact with reductions of FWHMASF (2D) and FWHM90° (volume rendering) of 23.8% and 23.6%, respectively, was observed. Although there was an expected increase in noise level, SNR values were preserved after deconvolution. Regardless of the methodology and visualization approach, the objective of reducing the out-of-plane artifact was accomplished. Both for the phantom and clinical case, the artifact reduction in the z was markedly visible. [ABSTRACT FROM AUTHOR]

Published
2020
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43. A Compensation Strategy Based on Consumer's Voltage Unbalance Assessment for a Distribution Static Synchronous Compensator.

Author

Neves Duarte, Samuel, Cortes de Souza, Bruno, Machado de Almeida, Pedro, Ramos de Araujo, Leandro, and Gomes Barbosa, Pedro

Abstract

This paper presents a new control algorithm for a distribution static synchronous compensator (DSTATCOM) based on consumer's voltage unbalance assessment. The proposed controller quantifies, in real time, the parcels of voltage unbalances due to the supplier (utility) and consumer by using local measurements of voltages and currents. The compensator mathematical model is used to derive small signal models in such a way to design controllers to compensate for the negative sequence voltage caused by a consumer. Two inner control loops, designed in synchronous reference frame, assure the DSTATCOM tracks the reference signals generated by the voltage controllers. Digital simulation results obtained with an unbalanced distribution network are used to validate the proposed methodology. The comparison of the results shows that the capacity of the compensator can be significantly reduced when only the unbalanced voltage portion caused by the load is compensated. [ABSTRACT FROM AUTHOR]

Published
2020
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