Abstract
It is shown how the design possibilities offered by double-layer uniform-waist tapered optical fibers (DLUWTs) permit to move the wavelength detection range to adapt the response of the sensors to varied conditions. In particular, we have obtained very good experimental curves showing that we can achieve plasmon resonances in the C-band of the optical communications, around 1.5 mu m, for the range of refractive indices of aqueous media, highly interesting in the biosensors field. Also, we show results for other interesting wavelength region, around 500 nm, where we can take advantage of the absorption peaks of the analytes. Finally, we explore the possibilities of using InN as a dielectric material for the second layer of the deposition. These results contribute to considerably expand the applicability and performance of SPR fiber sensors.

Abstract
This work introduces the coastal geo-engineering issues for a suitable selection and geomaterial characterisation of quarries. The development of the research had two main phases: (i) the field survey, applied cartography and inspection of maritime structures and (ii) the geological and geotechnical quarry assessment. This study reports results from the second phase which comprises the evaluation of quarries and the identification of potential areas for the extraction of armourstone with quality and availability to supply maritime structures. It was proposed a zoning of the NW Portugal region and taken into account some features like the land use, urban and settlement plans, geological setting, geotechnical and geomechanical description/typification of the rock masses. 459 quarries were identified, georeferenced and distributed in a total area of 14.010km2. More than 200 sites were selected, characterised and included in the GIS database project with interactive support (e.g. hyperlinks for the datasheets, photos or essential information). A total area of 4,1% was calculated, including relevant geological conditions and comprising existent quarries (active/inactive) or new places (suitable or predictable areas). A multidisciplinary perspective must be adopted providing a cost-effective method useful to the incorporation of important concepts (durability and integrity) in geo-monitoring coastal plans and highlighting GIS coastal projects.

Abstract
This study presents the results of a multidisciplinary approach, using hydrogeochemical, isotopic and ecotoxicological analyses, performed to assess the nature and suitability for use of Paranhos and Salgueiros spring waters (Porto city, NW Portugal). Based on the surface activities located along the course of the springs, 23 water samples were collected. All the samples were analysed for major element concentrations. The isotopic techniques employed included delta(2)H, delta(18)O and (3)H. Standard acute bioassays with Daphnia magna were also performed. The hydrogeochemical analyses showed a nitrate and sulphate-enriched composition for these groundwaters, resulting mainly from urban drainage and sewer leakage. In the ecotoxicological analyses, no significant mortality was observed in any of the tests performed. The results obtained in this study suggest that Porto urban groundwater could be suitable for irrigation uses.

Abstract
The Porto settlement (Northwest Portugal, Iberian Peninsula) was originally built in the twelfth century and has been developed on granitic hill slopes of the Douro riverside, being one of the oldest cities in Europe. In the urban area of Porto, the second most important city of the Portuguese mainland, there is a population of about 216,000 inhabitants. This study highlights the importance of urban speleological mapping applied to groundwater and geo-engineering studies. All the water that flows from the so-called Paranhos or Arca D'Agua springs is captured by catchwork galleries and their utilization date back around 1120 AD. Paranhos spring galleries catchworks (c. 3,3 km extension and a -21m below ground level) was one of the main water supplies to Porto City for more than six centuries and, nowadays, these waters are still appropriate for irrigation uses. Topographical, geological, geophysical and hydrogeological data were collected and interpreted, allowing the definition of a hydrogeotechnical zoning. All these features were mapped and overlaid using GIS mapping techniques. This multidisciplinary approach offers a good potential for reliable urban speleological and geo-engineering studies of Arca D'Agua site.

Abstract
A new approach to gas leakage detection in high pressure distribution networks is proposed, where the pipeline is modelled as a Linear Parameter Varying (LPV) System driven by the source node mass flow with the pressure as the scheduling parameter, and the system output as the mass flow at the offtake. Using a recently proposed successive approximations LPV system subspace identification algorithm, the pipeline is thus identified from operational data. The leak is detected using a Kalman filter where the fault is treated as an augmented state. The effectiveness of this method is illustrated with an example with a mixture of real and simulated data.

Abstract
The fitting of physical dynamical models to stimulus-response data such as the chemical concentration measured after a gas has been released to the environment, or the plasma concentration measured after an intravenous or oral input of a drug, are important problems in the area of system identification. Using models of different structures, one can obtain relevant statistical information on the parameters of the model from an array of software packages available in the literature. A meaningful interpretation of these parameters requires that in the presence of error-free data and an error-free model structure, a unique solution for the model parameters is guaranteed. This problem is known as a priori identifiability. Once the model is deemed identifiable, the parameters are then obtained, usually via a nonlinear least squares technique. In addition to identifiability, there is the problem of convergence of the parameters to the true values. It is a known fact that nonlinear parameter estimation algorithms do not always converge to the true parameter set. This is due to the fact that estimating the parameters of a nonlinear model can at times be an ill-conditioned problem. In this paper we use the same state space analysis techniques used to determine identifiability, to estimate the model parameters in a linear fashion. We approach the problem from a system identification point of view and then take advantage of the similarity transformation between the physical model and the identified model. We formulate the similarity relations and then transform them into a null space problem whose solution leads to the physical parameters. The novelty of our approach is in the use of a state space system identification algorithm to identify a black-box system, followed by a physical parameter extraction step using robust numerical tools such as the singular value decomposition.