Abstract
In cattle breeding industry, where artificial insemination techniques are employed, the successful detection of estrus onset leads to considerable cost-saving in herd management. One of the most reliable approaches is based on the determination of progesterone concentration in milk. However, these methods rely on the biosensor concept where a biological substrate is used in a chemical-binding reaction to directly or indirectly produce some effect (electrical or light) that is used at the transducer level. These methods present several drawbacks concerning real-time measurements due to the complexity of the reactions involved and reagent/waste handling. Another approach is to combine measurements of temperature and electrical resistance of reproductive tissues to predict estrus. Using a low-power microsystem with wireless capabilities it is possible to take these measurements in situ and more frequently. The proposed microsystem comprises a second-order delta-sigma modulator for analog-to-digital conversion and a class-E radio-frequency (RF) transmitter operating in the ISM-band of 433 MHz to transfer acquired data to a collar. Electrical resistance is measured by using a modified Wenner array and temperature by the on-chip temperature sensor. System (including battery and antenna) package is made of a tissue-compatible material to allow implantation in the cow's vulvar muscle. Since estrus prediction is based on relative changes of the two correlated parameters, calibration is not necessary. Some preliminary results regarding the measuring concept are presented.

Abstract
In studies of vadose zone flow and transport processes, there is a need for a multi-functional probe for small-scale measurements of different soil properties measured within identical soil volumes. The proposed multi-functional probe was designed for simultaneous measurement of temperature, volumetric water content, water flow, and salinity in small-scale soil volumes. The probe, without the heater element, will be a 21.4 mm diameter by 50 mm long cylinder. The proposed system includes signal processing circuits, a microcontroller, and a RF transceiver with ZigBee (TM) protocol. Heat-pulse simulations results showed a reasonably good agreement between measured and fitted data with small deviations at the tail of temperature response curves. In addition, results indicate that the Wenner array configuration provides an excellent tool for EC measurements in soil. In conclusion, results also show that it is possible to implement the multi-functional in a small-scale microsystem.

Abstract
This paper describes a CMOS mixed-signal interface with a RF transmitter. This die is assembled in a Multi-Chip-Module (MCM) micro-system together with the micromachined soil moisture sensor to achieve a cost-effective solution with accurate and reliable measurements for soil moisture in agriculture. The soil moisture probe, based on Dual-Probe Heat-Pulse (DPHP) method, is fabricated in bulk-micromachining technology. The DPHP method is based on the measurement of the maximum temperature rise at some distance from the heater, after applying a heat-pulse. The measurement of the temperature rise is obtained by subtracting soil temperature from the probe temperature. The mixed-signal interface is based on a pre-amplification stage and first-order sigma-delta modulator. The bit-stream output of the modulator is then applied to a counter as a first order decimation filter thus providing a 12-bit readout sample. Prior to transmission, data is encoded as a pulse width modulated (PWM) signal and then transmitted by means of an amplitude shift-keying (ASK) modulation. ne transmitter features a VCO phase locked to the quartz crystal reference of 13.56 MHz to achieve a carrier frequency of 433.92 MHz. A RF power amplifier based on class E topology was chosen. The CMOS mixed-signal interface with a RF transmitter has been implemented in a single-chip using a standard CMOS process (AMI 0.7 mum, n-well, 2 metals and I Poly).

Abstract
A soil moisture sensor (SMS) was built around RISC-like microcontroller and common peripherals to perform data acquisition, signal processing, configuration, fault-detection and data communication with a control/management system. The SMS employs capacitance and heat-pulse techniques to determine the soil water content. The sensor uses the capacitance technique as the main method while the heat-pulse readings, acquired at a lower rate, are used for calibration and fault detection purposes. The temperature sensors and the heater were assembled in a four-needle probe. Several experiments were conducted for different types of soil. The results showed that this sensor could be applied in an effective way to measure the soil water content. Several tests are being performed to conclude about the sensor dependence with soil temperature and chemical composition as well about its long-term stability.

Abstract
This work presents an on-chip silicon bulk-micromachined Soil Moisture Sensor (SMS) suited for irrigation control and management applications. The same basic fabrication concepts and materials, which made microelectronics successful, are now being adapted to making low-cost, small, high-performance sensor systems with integrated electronics on the same chip. As a result, this system-on-a-chip includes the SMS, readout electronics, self-test, calibration facilities and a digital bus interface for external data transmission, Moreover, since this sensor has low-cost, it could be employed several sensors networked together with the 1-wire bus, to achieve an accurate measure of the soil moisture at the plant root level. A 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. This method is based on the Joule effect (heater probe shank) and in Seebeck effect (thermopile - temperature probe shank). The heater and the thermopile are suspended on a dielectric window to reduce undesired heat conduction to the substrate (silicon is a good heat conductor). Thermal simulations of the bulk-micromachined SMS are performed to test sensor performance. In order to validate the method, simulations are made and experimental results were achieved with a macrosensor based on this technique. The results were compared with the measurements performed by the conventional thermo-gravimetric method.

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].