Abstract
Geophysical data represent subsoil structure in a specific area and can be used to extract subsoil information for various purposes. In this work we used this data type to detect anomalies/contamination in the subsoil. Our case study was based on data acquired around a landfill and the main objective is identifying contaminated areas as a result of leakage in landfill. This involves the application of statistical methods to detect anomalous values taking into account the whole data set, subdividing it in sublevels in relation to the surface, instead of using a single threshold (as usual). This work combines in the same software package the anomaly statistical analysis and several 3D representations of the results to validate and also helps understanding the final results of the analysis. Given that the original data used in the analysis, resistivity sections, is normally very sparse, a kriging geostatistical process was used to interpolate data in order to provide a volumetric representation of the subsoil in the area, providing a continuous spatial visualization. © 2012 IEEE.

Abstract
In the present moment, the sustainable water management is a major concern throughout the world. Mountain areas are more and more recognized as the world's water towers (UNESCO IHP-VI PROGRAMME). Since a large number of mountains are located at high altitude and are crossed by roads, deicing operations are inevitable. The use of deicing chemicals such as sodium chloride and calcium chloride to promote snow and ice melting in roads is an environmental problem of scientific, economic and social relevance. Due to its geological, geomorphological and climate characteristics, the Serra da Estrela mountain plays a strategic role in the water management in Portugal. This paper presents hydrogeochemical results that illustrate the process of groundwater contamination by road deicing salts in this mountain area. © 2012 LNEG.

Abstract

Abstract
Ultrasound transducers are typically based on piezoelectric materials, due to their good response at high frequencies. Depending on the application, ceramics, polymers and composite materials can be used. In this work, an optimization study of ultrasound transducers for underwater communications is addressed, focusing on a piston type emitter transducer operating in thickness mode (d(33)). The piston is constituted by an active element disk with optimized dimensions. It is discussed how the acoustic impedance, thickness, resonance frequency and structure affect the transducer performance. This work allows a better understanding of the emitter transducer characteristics allowing reaching the optimum point of operation for specific applications. Focusing on underwater communication, the acoustic channel is defined and the transducer is optimized by finite element computer simulations. The results were compared with experimental tests, which show that four-layer structures increase up to 16 dB in performance versus single-layer.

Abstract

Abstract