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Madrid, Spain

Fernandez Serrano R.,CEDEX | Fernandez Serrano R.,University Polite Cnica Of Madrid | Fernandez Serrano R.,New York University | Iskander M.,New York University | Tabe K.,Sharda University
Geotechnique Letters | Year: 2011

A physical model based on transparent soil technology is presented as a novel laboratory tool for ground contamination research. The model aims to reproduce both unsaturated and saturated conditions within a Spanish soil formation known as Miga sand. A soil surrogate made of a waterabsorbing polymeric gel was employed. Multi-phase flow froma leaking underground storage tank was simulated in both saturated and unsaturated conditions in order to illustrate the usefulness of the technique in simulating a hypothetical spill of a light non-aqueous phase liquid under well-controlled test conditions. The plume observed was found to be spatially variable. The technique permits, for the first time, the simulation of specific grain size distributions in a transparent soil surrogate and visualization of plume development in three dimensions. Preliminary results indicate that the model is a potentially powerful tool for visualising pollutant transport in porous media. A brief description of the test setup, and a summary of the advantages, limitations, and prospective applications are presented.


Karadimou E.,York EMC Services | Armstrong R.,York EMC Services | Adin I.,Centro de estudios e investigaciones tecnicas de Gipuzkoa | Deniau V.,IFSTTAR | And 4 more authors.
IEEE International Symposium on Electromagnetic Compatibility | Year: 2015

The research presented here deals with the electromagnetic compatibility in the railway environment. In particular it focuses on four research areas: the spot signalling systems, the track circuits, the GSM-R and the broadcasting services. A review of the current railway standards is followed by a research on the immunity limits, the worst case scenarios and cross acceptance EMC tests for the four areas. © 2015 IEEE.


Carvalho L.,European Commission - Joint Research Center Ispra | Carvalho L.,UK Center for Ecology and Hydrology | Mcdonald C.,UK Center for Ecology and Hydrology | de Hoyos C.,CEDEX | And 8 more authors.
Journal of Applied Ecology | Year: 2013

Summary: A safe, clean water supply is critical for sustaining many important ecosystem services provided by freshwaters. The development of cyanobacterial blooms in lakes and reservoirs has a major impact on the provision of these services, particularly limiting their use for recreation and water supply for drinking and spray irrigation. Nutrient enrichment is thought to be the most important pressure responsible for the widespread increase in cyanobacterial blooms in recent decades. Quantifying how nutrients limit cyanobacterial abundance in lakes is, therefore, a key need for setting robust targets for the management of freshwaters. Using a data set from over 800 European lakes, we highlight the use of quantile regression modelling for understanding the maximum potential capacity of cyanobacteria in relation to total phosphorus (TP) and the use of a range of quantile responses, alongside World Health Organisation (WHO) health alert thresholds for recreational waters, for setting robust phosphorus targets for lake management in relation to water use. The analysis shows that cyanobacteria exhibit a nonlinear response to phosphorus with the sharpest increase in cyanobacterial abundance occurring in the TP range from about 20 μg L-1 up to about 100 μg L-1. The likelihood of exceeding the World Health Organisation (WHO) 'low health alert' threshold increases from about 5% exceedance at 16 μg L-1 to 40% exceedance at 54 μg L-1. About 50% of the studied lakes remain below this WHO health alert threshold, irrespective of high summer TP concentrations, highlighting the importance of other factors affecting cyanobacteria population growth and loss processes, such as high flushing rate. Synthesis and applications. Developing a more quantitative understanding of the effect of nutrients on cyanobacterial abundance in freshwater lakes provides important knowledge for restoring and sustaining a safe, clean water supply for multiple uses. Our models can be used to set nutrient targets to sustain recreational services and provide different levels of precaution that can be chosen dependent on the importance of the service provision. Developing a more quantitative understanding of the effect of nutrients on cyanobacterial abundance in freshwater lakes provides important knowledge for restoring and sustaining a safe, clean water supply for multiple uses. Our models can be used to set nutrient targets to sustain recreational services and provide different levels of precaution that can be chosen dependent on the importance of the service provision. © 2013 British Ecological Society.


Lechuga A.,CEDEX
Natural Hazards and Earth System Sciences | Year: 2013

In past decades theoretical studies have been carried out with the double aim of improving knowledge of the main characteristics of the rogue wave and of attempting to predict its sudden appearance. We have tried to generate rogue waves in a water wave tank, using a symmetric spectrum (Akhmediev et al., 2011a) as input on the wave maker.

The next step has been to apply a theoretical model to the amplitude envelope of these waves. After some considerations we agreed the best model to be an analog of the Ginzburg-Landau equation. © 2013 Author(s).


Alaejos P.,CEDEX | Alaejos P.,Polytechnic University of Mozambique | Lanza V.,CEDEX
Cement and Concrete Research | Year: 2012

In this research, the effect on the reactivity of aggregates containing different quartz crystal sizes (0-10 μm; 10-60 μm, 60-130 μm) has been studied, proposing a unique limit for all of them applied to their weighted sum (Equivalent Reactive Quartz). For this aim, the expansion in mortar bars has been correlated with the content of reactive components, and values of the individual mathematic weights for different crystal sizes have been obtained: 8.3 vol.% of quartz 10-60 μm; and 2.6 vol.% of quartz < 10 μm (corresponding to 0.1% expansion at 14 days). The results show that 60-130 μm crystal size of quartz has a negligible effect on the expansion. These individual limits can be reduced to a unique one equal to 2.6 vol.% applied to the Equivalent Reactive Quartz. The use of this concept allows to evaluate the reactivity of aggregates in which there are simultaneously different reactive quartz crystal sizes. © 2011 Elsevier Ltd. All rights reserved.

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