Introduction
The Group of Technologies in hostile Environments (GTE) from the University of Zaragoza is constituted by a team of professors and researchers (nowadays about 14 people) from the University of Zaragoza which are also members of several consolidated groups (Real time,Perception and Robotics group, Power Electronics and Microelectronics group, Computer Architecture group, Applied Superconductivity group) and experts in many different areas: geology, electronics, communications, computer architecture, system engineering, embedded systems and real time systems. All Ph.D professors of the group belong to the Instituto de Investigación en Ingeniería de Aragón (I3A).
In addition to the Campus Río Ebro facilities of the University of Zaragoza in Zaragoza, since January 2005, the GTE is involved in the Laboratorios de Investigación Avanzada (Advanced Research Laboratories) of the WALQA technological park (Huesca) thanks to the signed agreement between the Gobierno de Aragón and the Instituto de Investigación en Ingeniería de Aragón (I3A).
Research activities
Confined environment communication
The wireless communication in confined environments poses though problems due to the fact that surrounding material (rock, soil, concrete, water, etc) has a conductivity which makes material to behave as a dissipative medium. This behaviour is known as skin effect. Therefore, in the vast majority of situations, radiofrequency waves are not capable of propagating through these materials more than a few meters. This conductivity also affects propagation of radiofrequency waves in tunnels or galleries. This effect is well known in mining and in railway tunnels. A transmission with a carrier frequency of 10MHz, usually can not be used farther than a mere 30m inside of a tunnel. Because of that, generally used wireless communications can not be used in confined environments. With these constraints, research objectives for the GTE group related to confined environments are:
- Voice and Data links using Through The Earth (TTE) communication. Research is oriented to several communication aspects such as: study and model of rock as a communication channel, study of noise and interferences present in the communication channel, study and optimisation of channel access, comparative study of the behaviour of different types of modulation techniques, voice compression algorithms, coding algorithms, filtering, etc for a given communication channel.
- Ad-Hoc networks oriented to easy the work of several activities like rescue, surveillance, exploitation, emergency, either for human or robot teams. Thus, research is focused on mobile ad-hoc networks capable of managing real time traffic for interfacing robots without previously deployed infrastructure and in ad-hoc protocols which support both QoS (voice or video) and real time traffic.
Radiolocation
Underground radiolocation is usually defined as the tracking down of an underground point in three dimensions (length, latitude and depth) from the surface. In order to make a radiolocation, a magnetic radio beacon is placed in the underground point. Nevertheless, radiofrequency waves suffer from a fast attenuation when travelling through rock and water depending on the frequency used. As long as the frequency decreases, wave penetration depth becomes larger. Classic radiolocation is based on the pattern of the magnetic field generated by the radio beacon. Soil conductivity, besides making the magnetic field propagation worse, it also distorts its radiation pattern, leading usually to errors in the finding of the underground point. As a part of the main research, a study to measure the relevance and magnitude of these errors in the radiolocation process and the development of new techniques to improve the precision is being made.
An ARVA (Appareil de Recherche de Victimes d'Avalanches) is a device designed to track down the victims of snow avalanches which are usually buried in the snow. The ARVA is also a radio beacon similar to the used in underground radiolocation and therefore it has the same problems with the magnetic field distortion. Its pretended to further expand underground radiolocation techniques and to research in the development of new ones, oriented to improve the speed and precision when tracking down victims of snow avalanches.
Karstic Hidrology
Another GTE research line is the study of karstic springs through new system identification techniques developed initially for system engineering. The main objective is to obtain models of karstic aquifers which allow its study, simulation and planning of the hydric resources it contains.