Artigos
URI permanente para esta coleçãohttps://repositorio.fei.edu.br/handle/FEI/798
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Artigo 45 Citação(ões) na Scopus Heuristically accelerated Q-learning: A new approach to speed up reinforcement learning(2004-01-05) Reinaldo Bianchi; RIBEIRO, C. H. C.; COSTA, A. H. R.This work presents a new algorithm, called Heuristically Accelerated Q-Learning (HAQL), that allows the use of heuristics to speed up the well-known Reinforcement Learning algorithm Q-learning. A heuristic function H that influences the choice of the actions characterizes the HAQL algorithm. The heuristic function is strongly associated with the policy: it indicates that an action must be taken instead of another. This work also proposes an automatic method for the extraction of the heuristic function H from the learning process, called Heuristic from Exploration. Finally, experimental results shows that even a very simple heuristic results in a significant enhancement of performance of the reinforcement learning algorithm. © Springer-Verlag 2004.Artigo de evento 4 Citação(ões) na Scopus Elbow flexion and extension movements characterization by means of EMG(2008-01-05) BITTAR, L. M.; Castro, M.C.F.Electromyographic (EMG) signal is the electrical manifestation of neuromuscular activation associated with muscle contraction. The present work intends to characterize the behavior of the muscles biceps and triceps during elbow flexion and extension movements, without load. These movements were performed at horizontal and vertical planes. Three types of test were performed, for each plane, relating EMG signal with joint position. Five men volunteers, ages ranged between 18 and 21 years old, were selected to participate to the tests. The first test consisted to move 10 degrees for each three seconds until the allowed maximum flexion and then, to return at the same way to the initial position. For the second test, the same movement was made but continuously, without stopping at intermediate positions. And for the third test, continuously flexion and extension movements were repeated sequentially but for different amplitudes, increasing by 10 degrees each. The tests were repeated, three times each. Initially, graphical analysis of the data was made for standard behavior detection and, for a quantitative analysis, after EMG preprocessing, averages and variation coefficients were calculated from specific intervals at the beginning, middle and at the end of movement. Although an EMG signals inherent variability, results showed inter and intra subject's repeatability, but only for movements performed at the horizontal plane.Artigo de evento 0 Citação(ões) na Scopus Study of circular gate SOI nMOSFET devices at high temperatures(2008-05-12) ALMEIDA, L. M.; BELLODI, M.The aim of this work is to evaluate the drain leakage current behavior in a Circular Gate (CG) SOI nMOSFET fabricated in 0.13 μm SOI CMOS technology. This technology is analyzed operating since room temperature up to 300°C, where the channel length and the geometrical drain bias terminal influence are analyzed in the drain leakage current behavior, when the devices are operating at high temperatures, through 3D numerical simulations. Since the CG SOI nMOSFET is not a symmetrical structure, it is possible to have two different configurations as following: the one which structure is configured with external drain and another one, with internal drain. Analyzing the drain leakage current behavior as a function of channel length at high temperatures, it is possible to observe that for the same channel length, as the temperature increases, it becomes higher and it increases as the channel length reduces. On the other hand, when the devices are operating with external drain, the drain leakage current becomes lower as compared to the internal drain, for both devices operating at same conditions. The results show that the drain leakage current depends strongly on the channel length and its density distribution is non uniform along the silicon film thickness. Besides it, also was observed that the drain leakage current depends on drain terminal configuration. Then, in order to understand the drain configuration influence in the drain leakage current behavior at high temperatures, the electric field was analyzed into the silicon film.Artigo 8 Citação(ões) na Scopus Study of matching properties of graded-channel SOI MOSFETs(2008-01-05) Michelly De Souza; FLANDRE, D.; Marcelo Antonio PavanelloIn this paper an overall analysis on the matching properties of Graded-Channel (GC) SOI MOSFETs in comparison to conventional SOI transistors is performed. Experimental results show that GC devices present poorer matching behavior in comparison to conventional SOI counterpart for equal mask channel length, whereas for same effective channel length, almost the same matching behavior. The analytical model for the drain current of GC devices is used to investigate the reasons for this matching worsening. Two-dimensional numerical simulations are used to validate the model-based analysis both in linear and saturation regions.- Application of Haar's wavelets in the method of moments to solve electrostatic problems(2004-09-01) Aldo Belardi; ROBERTO CARDOSO J.; FRANCA SARTORI, C. A.Presents the mathematical basis and some results, concerning the application of Haar's wavelets, as an expansion function, in the method of moments to solve electrostatic problems. Two applications regarding the evaluation of linear and surface charge densities were carried out: the first one on a finite straight wire, and the second one on a thin square plate. Some optimization techniques were used, whose main computational performance aspects are emphasized. Presents comparative results related to the use of Haar's wavelets and the conventional expansion functions. © 2004, Emerald Group Publishing Limited
- Wavelet's application in electrostatic and their computing aspects(2004-01-05) Aldo Belardi; Cardoso J. R.; Sartori C. A. F.This paper presents the mathematical basis, and some results, concerning the application of the Haar's Wavelets as the expansion function in the method of moments. Some computational optimization techniques are used, and their main aspects are stressed in the paper. As an example, the surface charge density on a finite and thin plane plate calculation is presented, in winch the main computational performance aspects are evaluated.
- Graded-channel SOI nMOSFET model valid for harmonic distortion evaluation(2006-05-17) Michelly De Souza; Marcelo Antonio Pavanello; CERDEIRA, A.; FLANDRE, D.In this paper an evaluation of the harmonic distortion of graded-channel SOI nMOSFETs is performed. The analysis is carried out by comparing an analytical continuous model and experimental results. The total harmonic distortion, as well as the third and second order terms are used as figures of merit in this comparison. It is shown that GC SOI devices present better gain and linearity behavior than conventional devices and that these advantages are well described by the proposed analytical model. The results show that the proposed set of equations is able to describe the linearity behavior of GC devices, indicating its potential to be used in analog circuit simulation and design. © 2006 IEEE.
- Contribution to application of wavelets in electrostatics Contribuição a aplicação das wavelets na eletrostática(2005-01-05) Aldo Belardi; CARDOSO, J. R.; SARTORI, C. A. F.This work presents the methodology from the determination the charge's superficial density, in two simple structure a to straight thread and in plane plates, both finite and submitted to a constant potential. That involves the method of the moments using as expansion function the wavelets instead of the pulse function, in order to reach a good precision and reducing the computational execution time. We also intends to take advantages of the wavelets application through the Cholesky decomposition, talking about formation of scattered matrixes, and the detection of nulls values.
- Saturation threshold voltage degradation in deep-submicrometer fully depleted SOI nMOSFETs operating in cryogenic environments(2005-10-03) Marcelo Antonio Pavanello; MARTINO, J. A.; SIMOEN, E.; CLAEYS, C.
- Electron valence-band tunnelling excess noise in twin-gate silicon-on-insulator MOSFETs(2006-01-05) SIMOEN, E.; CLAEYS. C.; LUKYANCHIKOVA, N.; GARBER, N.; SMOLANKA, A.; DER AGOPIAN, P. G.; MARTINO, J. A.The impact of using a twin-gate (TG) configuration on the Electron Valence-Band (EVB) tunnelling-related floating-body effects has been studied in partially depleted (PD) SOI MOSFETs belonging to a 0.13 μm CMOS technology. In particular, the influence on the so-called linear kink effects (LKEs), including the second peak in the linear transconductance (gm) and the associated Lorentzian noise overshoot was investigated. It is shown that while there is a modest reduction of the second gm peak, the noise overshoot may be reduced by a factor of 2. At the same time, little asymmetry is observed when switching the role of the slave and the master transistor, in contrast to the case of the impact ionization related kink effects. Two-dimensional numerical simulations support the observations and show that both the gm, the second gm peak and the body potential are changed in the TG structure compared with a single transistor. © 2005 Elsevier Ltd. All rights reserved.