A ordem econômico-constitucional e o mercado de etanol: diretivas de um marco regulatório para o estado democrático de direito

Pós-graduação em Direito - FCHS

Energetic-environmental assessment of a scenario for Brazilian cellulosic ethanol

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Proposta de metodologia para aplicação de eficiência energética em uma usina hidrelétrica

Pós-graduação em Engenharia Mecânica - FEG

Transient stability analysis of electric energy systems via a fuzzy ART-ARTMAP neural network

This work presents a methodology to analyze transient stability (first oscillation) of electric energy systems, using a neural network based on ART architecture (adaptive resonance theory), named fuzzy ART-ARTMAP neural network for real time applications. The security margin is used as a stability analysis criterion, considering three-phase short circuit faults with a transmission line outage. The neural network operation consists of two fundamental phases: the training and the analysis. The training phase needs a great quantity of processing for the realization, while the analysis phase is effectuated almost without computation effort. This is, therefore the principal purpose to use neural networks for solving complex problems that need fast solutions, as the applications in real time. The ART neural networks have as primordial characteristics the plasticity and the stability, which are essential qualities to the training execution and to an efficient analysis. The fuzzy ART-ARTMAP neural network is proposed seeking a superior performance, in terms of precision and speed, when compared to conventional ARTMAP, and much more when compared to the neural networks that use the training by backpropagation algorithm, which is a benchmark in neural network area. (c) 2005 Elsevier B.V. All rights reserved.

Measurement of Radiant Energy using Pyroelectric Polymer/Ceramic Composite

Monitoring non-ionizing radiant energy is increasingly demanded for many applications such as automobile, biomedical and security system. Thermal type infrared (IR) sensors can operate at room temperature and pyroelectric materials have high sensitivity and accuracy for that application. Working as thermal transducer pyroelectric sensor converts the non-quantified thermal flux into the output measurable quantity of electrical charge, voltage or current. In the present study the composite made of poly(vinylidene fluoride) -PVDF and lead zirconate titanate (PZT) partially recovered with polyaniline (PAni) conductor polymer has been used as sensor element. The pyroelectric coefficient p(T) was obtained by measuring the pyroelectric reversible current, i.e., measuring the thermally stimulated depolarization current (TSDC) after removing all irreversible contribution to the current such as injected charge during polarization of the sample. To analyze the sensing property of the pyroelectric material, the sensor is irradiated by a high power light source (halogen lamp of 250 W) that is chopped providing a modulated radiation. A device assembled in the laboratory is used to change the light intensity sensor, an aluminum strip having openings with diameters ranging from 1 to 10 mm incremented by one millimeter. The sensor element is assembled between two electrodes while its frontal surface is painted black ink to maximize the light absorption. The signal from the sensor is measured by a Lock-In amplifier model SR530 -Stanford Research Systems. The behavior of the output voltage for an input power at several frequencies for PZT-PAni/PVDF (30/ 70 vol%) composite follows the inverse power law (1/ f) and the linearity can be observed in the frequency range used.