Abstract
An adaptive greenhouse climate controller was implemented to regulate the air temperature, humidity and carbon dioxide concentration, with the aim of achieving set-point accuracy and reduce energy consumption. An optimization algorithm, based on the minimization of a cost function, was used to tune a Proportional-Integral-Derivative controller. The cost function is computed over a future time horizon of one hour as a function of the errors between the predicted and desired outputs and the predicted energy demand. Since the controller must be able to predict the greenhouse climate, it was needed to employ recursive identification algorithms to estimate in real-time the parameters of the climate model. When compared with commercially available controllers, this adaptive controller proved to have better performance regarding set-point accuracy and energy consumption.

Abstract
Competitive and cooperative artificial co-evolution using genetic algorithms are proposed to design PID control structures. A competitive coevolutionary based technique is proposed to design robust single-input single-output PID controllers to deal with prescribed parametric uncertainties. A cooperative coevolutionary approach and structured genetic algorithms are merged to cope with the identification of a multi-input multi-output plant within the problem of auto-tuning decentralised multivariable PI controllers. Simulated illustrative examples of both co-evolutionary techniques are presented. Copyright (C) 2000 IFAC.

Abstract

Abstract
The main objective of this paper is to present a study on the wind energy potential that is being developed in the Region of Tras-os-Montes and Alto Douro. This study started in July 1996 and will continue until the end of 1998. In order to have an adequate characterisation of the wind energy potential in this region it is necessary to measure the wind speed and direction in several places. At this moment the data are being collected at nine places. Due to lack of space, only four places will be addressed in this article. The Region of Douro and Alto Tras-os-Montes has an area of 12,235 km(2). It is located in the Northeast part of Portugal and represents 57.7% of the North Region. Other projects refer to this region as having great potential in the field of renewable energies [1,2]. From the analysis of the collected data, it seems that wind energy in Marao and Alvao mountains is one of the most interesting renewable energies [3,4].

Abstract
Psychrometer sensors are widely used for monitoring greenhouse air humidity because of its simplicity, low cost and accuracy. For proper operation the wick, which is immersed in a water reservoir, must maintain a continuous supply of water to the wet bulb temperature sensor. This implies the need to refill periodically the water reservoirs, which is the major limitation of these sensors. To avoid this problem an electronic psychrometric sensor was developed. A microcontroller is used to read the wet and dry bulbs temperatures and compute the vapor pressure and relative humidity. In addition, it controls a micro heat pump to supply continuously water to the reservoir.

Abstract
This paper presents an on-chip silicon bulk-micromachined Soil Moisture Sensor (SMS) for irrigation control in greenhouses. The system-on-a-chip includes the SMS, readout electronics, self-test, calibration facilities and a digital bus interface for external data transmission. Moreover, this low-cost device can be applied in several locations (e. g. per each plant root), and networked together with the 1-wire bus. The heat-pulse technique is used (for measuring the maximum temperature on a distant point) to determine the volumetric heat capacity and hence the water content of a porous media, such as soil. In order to validate this method, experimental results were achieved with a macrosensor based on the heat-pulse and capacitance methods. The capacitance method relates the volumetric water content with the capacitance change (dielectric properties) of a probe, inserted in the soil. Several tests were performed for different type of soils and water contents. These results are compared with the measurements achieved using the conventional thermogravimetric method.