Modelagem ambiental de uma casa de vegetação utilizando rede de osciladores de Van Der Pol. / Greenhouse environmental modeling using Van Der Pol oscillator network.

AUTOR(ES)

Marcos Alberto Bussab

DATA DE PUBLICAÇÃO

2007

RESUMO

Agricultural automation is an important area in the development of Brazilian production in recent years. Often, measurement and control of the internal conditions of greenhouses are not easy to implement at a reasonable cost. Researches in this area look for models using computational theory, foreseeing the behavior of internal variables of a greenhouse from the measurement of external variables. The objective of this work is to consider and evaluate the environmental modeling of a greenhouse using a Van der Pol oscillator network. The use of trustworthy models for forecasting internal conditions of a greenhouse is important for improving agricultural productivity. Some researches present an analytical and fuzzy model used to forecast the relative humidity and internal temperature of a greenhouse. As first approach, a model based on a multilayer neural network was implemented. The neural network activation functions change for a Van Der Pol oscillator can produce better results when modeling non-linear process, and in this case, reduced estimate errors without compromising its computational performance. The measured experimental data and the estimated data were compared with statistical criteria. The relative error for the measured values of temperature varied from 0.0% through 1.5%, while the relative error of the measured values for the relative humidity varied from 0.5% through 6.9%. The relative error for both measured variables presented better behavior for the model considered in relation to the analytic, fuzzy, and neural network models. The average computational performance of the model with Van Der Pol oscillators, when compared with the neural network model, considering the number of iterations decreased approximately 7.8%. The results demonstrate that modeling based on Van der Pol oscillators is viable for forecasting the internal variables of a greenhouse.

ASSUNTO(S)

oscillators estufas variáveis ambientais internas (modelagem) internal envirionmental variables (modeling) osciladores greenhouse

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