Abstract
This paper analyses the performance of a genetic algorithm using a new concept, namely a fractional-order dynamic fitness function, for the synthesis of combinational logic circuits. The experiments reveal superior results in terms of speed and convergence to achieve a solution.

Abstract
Crop models are useful to improve the management and control of the greenhouse climate. In fact, they are essential if it is intended to optimize the climate control according to a defined production plan. In this paper are reviewed simulation models developed for horticultural crops with emphasis on leaf area and dry matter production. The dynamic crop models are based on the description of the crop photosynthesis and respiration processes. Various models were tested for a tomato crop grown in a greenhouse with a soil medium. The environmental factors such as air temperature and humidity, photosynthetic flux density, carbon dioxide concentration, among others, were measured, with a sampling rate of 1 minute and the mean values were stored with a 30min time interval. Plant leaf area and fresh and dry weights were measured by conducing periodic destructive tests. The results achieved with the different models employed are discussed and their applicability addressed.

Abstract
In the recent past, the distance between the sensing and processing points imposed critical constraints on the application of most PC-based data acquisition and control systems. Nowadays, it is possible to access the control systems installed in remote sites over the Internet. The World Wide Web has revolutionised the Internet by providing a medium for the dissemination of information, and the use of this technology can have a great impact on Agricultural Systems as well. These technologies allow almost any PC with a browser and a communication link to the Greenhouses to be used as an operator workstation, which gives benefits to the users who need remote access to greenhouses. Besides this, modern systems for agricultural applications are based on interconnection and integration of several Local Area Network (LAN) technologies combining data connectivity with user mobility. With a browser, the user is able to download a set of web pages, review information about the status of the system in real time, by running Java Applets, and display it in a browser window. Also, in this way it is possible to remotely configure any network node.

Abstract
This paper describes a computer-based temperature control system for a growth chamber. The system consists of a low cost computer with a data acquisition card acting as the interface between the process and the computer. The software developed has a menu-driven user friendly interface to access execute the functions implemented: choice of the sampling interval, choice of the setpoints, name files, etc.. The user can program up to six different temperature setpoints as constituting six time programmable events along the day. The identification of the thermal process was made from the analysis of the output data collected from the process in response to random generated input signals. Using this model it was possible to establish optimal linear and non linear control strategies in order to achieve the desired setpoint and to minimize the number of actuation. The actuation over the heating and cooling systems were performed with conventional PID and fuzzy controllers and their responses were compared.

Abstract
In this paper climate discrete-time dynamic models for the inside air temperature of two different greenhouses are identified, using data acquired during two different periods of the year. These models employ data from air temperature and relative humidity (both inside and outside the greenhouse), solar radiation, wind speed and control inputs (ventilation, etc.), acquired with a sampling rate of 30s and storage rate of 1 min. Using software developed with Matlab, and its Identification Toolbox, the structure of the dynamic transfer functions is first selected, and its parameters afterwards identified using off-line techniques. Several simulations experiments show that the second-order models identified achieve a close agreement between simulated and experimental data. As different model parameters were obtained for each case studied, implying that the system is time-varying, these models must be obtained in real-time, employing on-line identification techniques. These models will afterwards be used in real-time climate control, where different control strategies will be compared, with respect to set-point accuracy, energy consumption and actuator wear.

Abstract