Abstract
Using the new trend of energy harvesting, an envisioned electromagnetic power transducer that uses human gait to produce electrical energy is presented as a solution to energize biomedical devices. Regardless of the walking speed, starting at 0.7 Hz, it is possible to store a total energy of 2.2 mJ, using two 1000 mu F capacitors as energy storage elements. Afterwards, this energy becomes available to the telemetric system through an efficient power management module. Since the end application, an implantable biomedical telemetric system, needs a total of 360 mu J to operate, the here presented power transducer is well suited for implant power needs.

Abstract
This article describes a new electrical conductance converter method suitable for very low power applications, where energy constraints prevails over speed and measurement accuracy. Method idea gather voltage time integration and shopper stabilization techniques to process noisy low amplitude signals and to overcome severe limitations of weak inversion channel CMOS circuitry. Main features and tradeoffs are exploited. A 1.2V ASIC implementation on standard 0.35µm CMOS schematics is also presented. Post-layout simulations shows a total power consumption lower than 900nW including current source excitation inherent to the conductance measurement. Such low power consumption allows the measurement of several physical parameters on self-powered wireless networks. © 2010 by Department of Microelectronics & Computer Science, Technical University of Lodz.

Abstract
This paper describes the implementation of a wireless data acquisition network for agricultural applications based on the Microchip PIC16C71, and the Intel 87C592 microcontrollers. The system uses a set of solar powered wireless data-acquisition stations (SPWAS) linked by radio frequency to a base station (BS). The base station has as main functions the control of the data-acquisition stations and the storage of the data collected by them. The network has been applied to collect outdoor and indoor climate data from a set of greenhouses located at Universidade de Tras-os-Montes e Alto Douro (UTAD), in the northwest of Portugal. Experimental tests are being done since mid June 1996, and the results obtained shows that the communications to the BS station were performed without errors and no loss of data.

Abstract
Greenhouse control computers are an essential part of modern greenhouse operation. Climate, irrigation and nutrient supply must be controlled, in an economical way, to produce the best crop conditions. Current research on CO2 enrichment and optimal growth strategies implies the use of powerful tools, either based on hardware or software. This paper describes the design and implementation of a distributed data acquisition and control system for computerised agricultural management systems that is being developed at Universidade of Tras-os-Montes and Alto Douro, Vila Real. Different communications platform concepts, such as Controller Area Network (CAN), Wireless Technologies, Ethernet and Internet tools supported by Transfer Control Protocol/Internet Protocol (TCP/IP) and e-mail tools supported by Simple Mail Transfer Protocol (SMTP) were used to achieve a network with a low-cost, flexible, and functional characteristics. The system management and maintenance tasks are divided into two types of performance levels. At a lower supervision level, a Local Controller placed in the greenhouses performs the monitoring/control and communications actions. The management decisions are performed at the higher level. The techniques and tools, which provide to the user a transparent, friendly and intuitive Graphical User Interface (GUI) will be presented.

Abstract
This paper describes the goals and some of the results obtained in the project entitled "Computerised Management of Greenhouses", that has started in November 1995. This project has a duration of three years and is sponsored by JNICT (Portuguese Institute for Scientific Research Funding). At present, the experimental set-up is composed of a greenhouse with a floor area of 210m(2) equipped with several actuators and sensors that are connected to an acquisition and control system developed at the Engineering Department of UTAD University. The set-points for the air temperature and humidity, CO2 concentration, soil moisture and ambient radiation inside the greenhouse are calculated on-line as a function of the greenhouse climate, outside weather and the specified optimal set of values for the plants, in this case tomato. The results show that the climate control system performs well and that has been achieved a reduction of the energy consumption compared with the case when the set-points are fixed. In the second year it will be implemented a distributed control system for monitoring and control the environment of four greenhouses located at the University campus. Also, in one of the greenhouses, will be used renewable energies such as the solar photovoltaic and the solar thermal energies. The first is to deliver power to the electronic equipment and to some of the actuators and the second for heating the greenhouses. During this period and the third year it will be implemented and compared different real-time control strategies with respect to set-point accuracy and energy consumption.

Abstract
Improvement of crop quality and yields is a demand in modern greenhouse production systems. Also, production costs must be kept as low as possible to guarantee market competitiveness. The achievement of these goals implies the use of complex management and control systems to regulate, in an efficient way, a large amount of interactive physical variables. Recent developments in hardware and software tools, namely microprocessors and microcontrollers, lead to the integration of complex control and management tasks in agricultural exploitations. In this paper is presented a data acquisition and control network that was implemented with the aim of being applied to any agricultural environment. The network has three main operating levels. At the lower level, a set of remote microcontroller stations perform data acquisition and radio frequency transmission to a collecting and control station. The control station, which generates actuating signals, is linked to a higher-level network based on PC's. The management and supervision of the entire greenhouse system is performed at this lever. Also, the results achieved with its application to the environmental control of a set of greenhouses located in the north of Portugal are described. The proposed architecture is now being installed in several commercial exploitations in order to evaluate its performance and introduce any improvements required by the growers. After this phase, the network will be available commercially through a joint Venture between UTAD University and a Portuguese greenhouse constructor.