Maps and acoustic profiles of free gas distribution, Western Baltic Sea and Kattgat-Skagerrak area

A shallow gas depth-contour map covering the Skagerrak-western Baltic Sea region has been constructed using a relatively dense grid of existing shallow seismic lines. The digital map is stored as an ESRI shape file in order to facilitate comparison with other data from the region. Free gas usually occurs in mud and sandy mud but is observed only when sediment thickness exceeds a certain threshold value, depending on the water depth of the area in question. Gassy sediments exist at all water depths from approx. 20 m in the coastal waters of the Kattegat to 360 m in the Skagerrak. In spite of the large difference in water depths, the depth of free gas below seabed varies only little within the region, indicating a relatively fast movement of methane in the gas phase towards the seabed compared to the rate of diffusion of dissolved methane. Seeps of old microbial methane occur in the northern Kattegat where a relatively thin cover of sandy sediments exists over shallow, glacially deformed Pleistocene marine sediments. Previous estimates of total methane escape from the area may be correct but the extrapolation of local methane seepage rate data to much larger areas on the continental shelf is probably not justified. Preliminary data on porewater chemistry were compared with the free gas depth contours in the Aarhus Bay area, which occasionally suffers from oxygen deficiency, in order to examine if acoustic gas mapping may be used for monitoring the condition of the bay.

Occurrence and chemistry of microtektites of ODP Site 121-758

The Toba lake event, the Australasian microtektite event, and the Cretaceous/Paleogene boundary were analyzed on the basis of foraminifers, carbonate content, trace elements, and spherules (microtektites). The Toba ash event, recovered in Hole 758C, may have had minor influences on the foraminiferal populations. The Australasian tektite event has probably some influence on foraminiferal ecology, because the larger specimens become scarce just above the microtektite layer. Microtektites recovered from Hole 758B closely resemble spherules recovered from several Cretaceous/Paleogene boundary localities in North America. The Cretaceous/Paleogene spherules, however, are usually larger and are completely altered to goyazite in the terrestrial environment and to smectite in a marine environment. The Cretaceous/Paleogene boundary of Hole 752B does not show obvious anomalous trace-element concentrations, and iridium concentrations are below our detection limits. The trace-element pattern is dominated by the alternation of chalk with volcanic ash layers above the Cretaceous/Paleogene boundary.

Underway measurements of halocarbons (air) during POSEIDON cruise POS399 in June 2010

During the DRIVE (Diurnal and Regional Variability of Halogen Emissions) ship campaign we investigated the variability of the halogenated very short-lived substances (VSLS) bromoform (CHBr3), dibromomethane (CH2Br2) and methyl iodide (CH3I) in the marine atmospheric boundary layer in the eastern tropical and subtropical North Atlantic Ocean during May/June 2010. The highest VSLS mixing ratios were found near the Mauritanian coast and close to Lisbon (Portugal). With backward trajectories we identified predominantly air masses from the open North Atlantic with some coastal influence in the Mauritanian upwelling area, due to the prevailing NW winds. The maximum VSLS mixing ratios above the Mauritanian upwelling were 8.92 ppt for bromoform, 3.14 ppt for dibromomethane and 3.29 ppt for methyl iodide, with an observed maximum range of the daily mean up to 50% for bromoform, 26% for dibromomethane and 56% for methyl iodide. The influence of various meteorological parameters - such as wind, surface air pressure, surface air and surface water temperature, humidity and marine atmospheric boundary layer (MABL) height - on VSLS concentrations and fluxes was investigated. The strongest relationship was found between the MABL height and bromoform, dibromomethane and methyl iodide abundances. Lowest MABL heights above the Mauritanian upwelling area coincide with highest VSLS mixing ratios and vice versa above the open ocean. Significant high anti-correlations confirm this relationship for the whole cruise. We conclude that especially above oceanic upwelling systems, in addition to sea-air fluxes, MABL height variations can influence atmospheric VSLS mixing ratios, occasionally leading to elevated atmospheric abundances. This may add to the postulated missing VSLS sources in the Mauritanian upwelling region (Quack et al., 2007).

Examples of PDEs all whose points are characteristic

Let π : FM ! M be the bundle of linear frames of a manifold M. A basis Lijk , j < k, of diffeomorphism invariant Lagrangians on J1 (FM) was determined in [J. Muñoz Masqué, M. E. Rosado, Invariant variational problems on linear frame bundles, J. Phys. A35 (2002) 2013-2036]. The notion of a characteristic hypersurface for an arbitrary first-order PDE system on an ar- bitrary bred manifold π : P → M, is introduced and for the systems dened by the Euler-Lagrange equations of Lijk every hypersurface is shown to be characteristic. The Euler-Lagrange equations of the natural basis of Lagrangian densities Lijk on the bundle of linear frames of a manifold M which are invariant under diffeomorphisms, are shown to be an underdetermined PDEs systems such that every hypersurface of M is characteristic for such equations. This explains why these systems cannot be written in the Cauchy-Kowaleska form, although they are known to be formally integrable by using the tools of geometric theory of partial differential equations, see [J. Muñoz Masqué, M. E. Rosado, Integrability of the eld equations of invariant variational problems on linear frame bundles, J. Geom. Phys. 49 (2004), 119-155]

La dimensión de la subjetividad en la formación del valor inmobiliario : aplicación del método de análisis de ecuaciones estructurales al mercado residencial de Lisboa

The discretionality and the appraisers’ subjectivity that characterize traditional real estate valuation are still allowed to take part in the formation of the asset price even when respecting international standards (EVS, IVS) or Appraisal Institution´s regulations (TEGOVA, RICS, etc.). The application of econometric and statistical methods to real estate valuation aims at the elimination of subjectivity on the appraisal process. But the unanswered question underneath this subject is the following: How important is the subjective component on real estate appraisal value formation? On this study Structural Equation Models (SEM) are used to determine the importance of the objective and subjective components on real estate valuation value formation as well as the weight of economic factors and the current economic context on real estate appraisal for mortgage purposes price formation. There were used two latent variables, Objective Component and Subjective Component, witch aggregate objective observed variables and subjective observed and unobserved variables, respectively. Factorial Exploratory Analysis is the statistical technique used in order to link the observed variables extracted from the valuation appraisal reports to the latent constructs derived from the theoretical model. SEM models were used to refine the model, eliminate non‐significant variables and to determine the weight of Objective and Subjective latent variables. These techniques were applied to a sample of over 11.000 real estate assets appraisal reports throughout the time period between November of 2006 and April of 2012. The real assets used on this study are located on Lisbon’s Metropolitan Area – “Grande Lisboa” –, Portugal. From this study, we conclude that Subjective Component has a considerable weight on real estate appraisal value formation and that the external factor Economic Situation has a very small impact on real estate appraisal value formation.

Adams methods: implementation as predictor-corrector methods

In this paper, Adams explicit and implicit formulas are obtained in a simple way and a relationship between them is established, allowing for their joint implementation as predictor-corrector methods. It is shown the purposefulness, from a didactic point of view, of Excel spreadsheets for calculations and for the orderly presentation of results in the application of Adams methods to solving initial value problems in ordinary differential equations.

Degradation in seawater of structural adhesives for hybrid fibre-metal laminated materials

The adhesives used for applications in marine environments are subject to particular chemical conditions, which are mainly characterised by an elevated chlorine ion content and intermittent wetting/drying cycles, among others.These conditions can limit the use of adhesives due to the degradation processes that they experience. In this work, the chemical degradation of two different polymers, polyurethane and vinylester, was studied in natural seawater under immersion for different periods of time.The diffusion coefficients and concentration profiles of water throughout the thickness of the adhesiveswere obtained.Microstructural changes in the polymer due to the action of water were observed by SEM, and the chemical degradation of the polymer was monitored with the Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The degradation of the mechanical properties of the adhesive was determined by creep tests withMixed Cantilever Beam (MCB) specimens at different temperatures. After 180 days of immersion of the specimens, it was concluded that the J-integral value (depending on the strain) implies a loss of stiffness of 51% and a decrease in the failure load of 59% for the adhesive tested.

Optical memory with twisted nematic liquid crystal (TNLC) devices

A design for obtaining memory in optical bistability with liquid crystals is reported. This design uses optical feedback on a twisted nematie liquid crystal ( TNLC ) through an optoelectronic system. A constant input light is the read-out and its value depends on the desired initial working point, usually at the bottom of the T(V) vs. V curve. Light levels depend on the feedback. An input light pulse change the working point to the top of the transmission curve. When this pulse vanishes, the working point remains at the upper part of the curve. Hence a memory function is obtained. Minimum pulse width needed was 1msec. ON-OPF ratio was 100:3.

Dominance intensity measure within fuzzy weight oriented MAUT: an application

We introduce a dominance intensity measuring method to derive a ranking of alternatives to deal with incomplete information in multi-criteria decision-making problems on the basis of multi-attribute utility theory (MAUT) and fuzzy sets theory. We consider the situation where there is imprecision concerning decision-makers’ preferences, and imprecise weights are represented by trapezoidal fuzzy weights.The proposed method is based on the dominance values between pairs of alternatives. These values can be computed by linear programming, as an additive multi-attribute utility model is used to rate the alternatives. Dominance values are then transformed into dominance intensity measures, used to rank the alternatives under consideration. Distances between fuzzy numbers based on the generalization of the left and right fuzzy numbers are utilized to account for fuzzy weights. An example concerning the selection of intervention strategies to restore an aquatic ecosystem contaminated by radionuclides illustrates the approach. Monte Carlo simulation techniques have been used to show that the proposed method performs well for different imprecision levels in terms of a hit ratio and a rank-order correlation measure.

Numerical and experimental study of overtopping and failure of rockfill dams

This paper aims to present and validate a numerical technique for the simulation of the overtopping and onset of failure in rockfill dams due to mass sliding. This goal is achieved by coupling a fluid dynamic model for the simulation of the free surface and through-flow problems, with a numerical technique for the calculation of the rockfill response and deformation. Both the flow within the dam body and in its surroundings are taken into account. An extensive validation of the resulting computational method is performed by solving several failure problems on physical models of rockfill dams for which experimental results have been obtained by the authors.

Solution of optimal continuous low-thrust transfer using Lie transforms

This paper addresses the problem of optimal constant continuous low-thrust transfer in the context of the restricted two-body problem (R2BP). Using the Pontryagin’s principle, the problem is formulated as a two point boundary value problem (TPBVP) for a Hamiltonian system. Lie transforms obtained through the Deprit method allow us to obtain the canonical mapping of the phase flow as a series in terms of the order of magnitude of the thrust applied. The reachable set of states starting from a given initial condition using optimal control policy is obtained analytically. In addition, a particular optimal transfer can be computed as the solution of a non-linear algebraic equation. Se investiga el uso de series y transformadas de Lie en problemas de optimización de trayectorias de satélites impulsados por motores de bajo empuje

Efficient computation of current collection in bare electrodynamic tethers in and beyond OML regime

One key issue in the simulation of bare electrodynamic tethers (EDTs) is the accurate and fast computation of the collected current, an ambient dependent operation necessary to determine the Lorentz force for each time step. This paper introduces a novel semianalytical solution that allows researchers to compute the current distribution along the tether efficient and effectively under orbital-motion-limited (OML) and beyond OML conditions, i.e., if tether radius is greater than a certain ambient dependent threshold. The method reduces the original boundary value problem to a couple of nonlinear equations. If certain dimensionless variables are used, the beyond OML effect just makes the tether characteristic length L ∗ larger and it is decoupled from the current determination problem. A validation of the results and a comparison of the performance in terms of the time consumed is provided, with respect to a previous ad hoc solution and a conventional shooting method.

Estudio de la dinámica no lineal de vórtices magnéticos en nanodots

En el presente trabajo se ha realizado un estudio sobre el comportamiento dinámico de vórtices magnéticos en su aplicación en osciladores de espín-torque. A partir de los modelos matemáticos elaborados en [4] sobre estos osciladores de espín-torque, se han simulado y estudiado usando MATLAB, entre otras herramientas, para tratar de verificar su concordancia con el comportamiento físico observado en el laboratorio. Es importante señalar que el estudio tiene en cuenta la dinámica no lineal, esencial para describir correctamente un sistema oscilante en la práctica. El análisis matemático del sistema que describe la órbita del núcleo de un vórtice magnético sometido a la acción de un campo magnético externo oscilatorio, muestra la posibilidad de la existencia de hasta tres soluciones especiales, según la geometría del dot y el valor del campo magnético de excitación, tanto de su frecuencia como de su amplitud. Estas soluciones corresponden a estados estacionarios del vórtice caracterizados como una órbita circular, aunque en el caso de existir tres equilibrios uno de ellos es inestable. El modelo matemático ha sido estudiado y analizado para reproducir los resultados obtenidos en [4] y adicionalmente se ha implementado el caso de la energía potencial del vórtice con el término no lineal distinto de [4] (con una constante β negativa). Los resultados obtenidos bajo esta suposición muestran una cierta disparidad respecto al caso de β positiva y reflejan la existencia de comportamientos muy diferentes. En la dinámica del vórtice bajo la suposición de β negativa también surgen bifurcaciones de pliegue (fold-over) en la trayectoria del núcleo del vórtice: siempre se obtienen tres equilibrios a bajas frecuencias y aparecen a veces dos intervalos con tres equilibrios en lugar de uno solo, a diferencia del caso de β positiva. El comportamiento del núcleo del vórtice sigue un proceso de histéresis en ambos casos, cuando se dan ciertas condiciones. ABSTRACT. This work is a study about the dynamic behaviour of magnetic vortex in its application in spin-torque oscillators. Starting from mathematical models developed in [4] on this subject, a further analysis has been performed using MATLAB to simulate the behaviour of vortex-based spin-torque oscillators as different relevant parameters vary. The main aim of the study is to check if the obtained results can explain the observed physical behaviour, and an important observation is that fully nonlinear effects are taken into consideration. The mathematical analysis of the system that describes the orbit of the vortex core under the influence of an external oscillatory magnetic field shows that there are up to three possible special solutions depending on the dot geometry and the magnetic driving field value, both on its amplitude as well as its frequency. These solutions correspond to a stable circular orbit of the vortex core, but when the system has three solutions one of them is unstable. This mathematical model has been analyzed and studied to reproduce the results obtained in [4] and, additionally, the effect of a negative value of the nonlinear part of the vortex potential (constant β). Results derived from this assumption exhibit certain differences with respect to the case of a positive constant (β) and reflect the existence of very different patterns. Vortex dynamics under the supposition of a negative β also yield fold-over bifurcations in the trajectory of the vortex core: there are always three solutions at low frequencies and there may be two different intervals with three solutions as opposed to the case of positive β. The vortex core follows a hysteresis process in both cases, when certain conditions are met.

Herramienta web para la ayuda a la generación de consenso

En la actualidad encontramos una gran y creciente cantidad de información en las redes sociales. Esta información en su mayoría se encuentra desestructurada o no organizada de forma adecuada, esto produce que sea difícil alcanzar consensos en argumentaciones y además impide la rápida participación de nuevos agentes en las mismas. Se han estudiado diferentes soluciones para alcanzar consensos en áreas concretos y en su mayoría centrados en el entorno académico, sin embargo se pueden encontrar pocas aplicaciones que traten de acercarse a una solución dentro de un contexto abierto como son las redes sociales. El contexto de las redes sociales es complejo pues no existe un control sobre los usuarios, los hilos de argumentación pueden desvirtuarse y es complejo alcanzar consensos cuando no existe una figura de experto bien definida como suele ocurrir en el contexto académico. Este trabajo trata de crear una herramienta web en forma de red social, con una base en sistemas inteligentes que permita a los usuarios poder obtener suficiente información de una conversación minimizando el esfuerzo para poder participar activamente.---ABSTRACT---Nowadays a large and an increasing amount of information can be found on social networks. This information is mostly unstructured and not properly organized, which is a problem when conclusions are needed to reach a consensus in argumentations. In addition new participants can find difficulties to join argumentations. Different solutions have been studied to solve these problems focused in academic contexts, however few applications which attempt to solve these problems on social networks can be found. It is not a simple task to handle the complexity of arguments on a social network. Besides, the free context and the lack of control over users make reaching a consensus even harder. This academic work seeks to create a tool in the form of an intelligent systems based social networks which may allow users to minimize the effort needed to join and participate in an argumentation.

Estudio teórico-experimental sobre el deterioro en tableros de puentes de hormigón producido por la acción del hielo-deshielo con sales de fundentes

El deterioro del hormigón por ciclos de hielo-deshielo en presencia de sales fundentes es causa frecuente de problemas en los puentes e infraestructuras existentes en los países europeos. Los daños producidos por los ciclos de hielo-deshielo en el hormigón pueden ser internos, fundamentalmente la fisuración y/o externos como el descascarillamiento (desgaste superficial). La España peninsular presenta unas características geográficas y climáticas particulares. El 18% de la superficie tiene una altura superior a 1000mts y, además, la altura media geográfica con respecto al nivel del mar es de 660mts (siendo el segundo país más montañoso de toda Europa).Esto hace que la Red de Carreteras del Estado se vea afectada, durante determinados periodos, por fenómenos meteorológicos adversos, en particular por nevadas y heladas, que pueden comprometer las condiciones de vialidad para la circulación de vehículos. Por este motivo la Dirección General de Carreteras realiza trabajos anualmente (campañas de vialidad invernal, de 6 meses de duración) para el mantenimiento de la vialidad de las carreteras cuando éstas se ven afectadas por estos fenómenos. Existen protocolos y planes operativos que permiten sistematizar estos trabajos de mantenimiento que, además, se han intensificado en los últimos 10 años, y que se fundamentan en el empleo de sales fundentes, principalmente NaCl, con la misión de que no haya placas de hielo, ni nieve, en las carreteras. En zonas de fuerte oscilación térmica, que con frecuencia en España se localizan en la zona central del Pirineo, parte de la cornisa Cantábrica y Sistema Central, se producen importantes deterioros en las estructuras y paramentos de hormigón producidos por los ciclos de hielo- deshielo. Pero además el uso de fundentes de vialidad invernal acelera en gran medida la evolución de estos daños. Los tableros de hormigón de puentes de carretera de unos 40-50 años de antigüedad carecen, en general, de un sistema de impermeabilización, y están formados frecuentemente por un firme de mezcla asfáltica, una emulsión adherente y el hormigón de la losa. En la presente tesis se realiza una investigación que pretende reproducir en laboratorio los procesos que tienen lugar en el hormigón de tableros de puentes existentes de carreteras, de unos 40-50 años de antigüedad, que están expuestos durante largos periodos a sales fundentes, con objeto de facilitar la vialidad invernal, y a cambios drásticos de temperatura (hielo y deshielo). Por ello se realizaron cuatro campañas de investigación, teniendo en cuenta que, si bien nos basamos en la norma europea UNE-CEN/TS 12390-9 “Ensayos de hormigón endurecido. Resistencia al hielo-deshielo. Pérdida de masa”, se fabricaron probetas no estandarizadas para este ensayo, pensado en realidad para determinar la afección de los ciclos únicamente a la pérdida de masa. Las dimensiones de las probetas en nuestro caso fueron 150x300 mm, 75 x 150mm (cilíndricas normalizadas para roturas a compresión según la norma UNE-EN 12390-3) y 286x76x76 (prismáticas normalizadas para estudiar cambio de volumen según la norma ASTM C157), lo cual nos permitió realizar sobre las mismas probetas más ensayos, según se presentan en la tesis y, sobre todo, poder comparar los resultados con probetas extraídas de dimensiones similares en puentes existentes. En la primera campaña, por aplicación de la citada norma, se realizaron ciclos de H/D, con y sin contacto con sales de deshielo (NaCl en disolución del 3% según establece dicha norma). El hormigón fabricado en laboratorio, tratando de simular el de losas de tableros de puentes antiguos, presentó una fc de 22,6 MPa y relación agua/cemento de 0,65. Las probetas de hormigón fabricadas se sometieron a ciclos agresivos de hielo/deshielo (H/D), empleando una temperatura máxima de +20ºC y una temperatura mínima de -20ºC al objeto de poder determinar la sensibilidad de este ensayo tanto al tipo de hormigón elaborado como al tipo de probeta fabricado (cilíndrica y prismática). Esta campaña tuvo una segunda fase para profundizar más en el comportamiento de las probetas sometidas a ciclos H/D en presencia de sales. En la segunda campaña, realizada sobre probetas de hormigón fabricadas en laboratorio iguales a las anteriores, la temperaturas mínima del ensayo se subió a -14ºC, lo que nos permitió analizar el proceso de deterioro con más detalle. (Realizando una serie de ensayos de caracterización no destructivos y otros destructivos, y validando su aplicación a la detección de los deterioros causados tras los ensayos acelerados de hielodeshielo. También mediante aplicación de técnicas de microscopía electrónica.) La tercera campaña, se realizó sobre probetas de hormigón de laboratorio similares a las anteriores, fc de 29,3Mpa y relación a/c de 0,65, en las que se aplicó en una cara un revestimiento asfáltico de 2-4cms, según fueran prismáticas y cilíndricas respectivamente, compuesto por una mezcla asfáltica real (AC16), sobre una imprimación bituminosa. (Para simular el nivel de impermeabilización que produce un firme sobre el tablero de un puente) La cuarta campaña, se desarrolló tras una cuidadosa selección de dos puentes de hormigón de 40-50 años de antigüedad, expuestos y sensibles a deterioros de hielodeshielo, y en carreteras con aportación de fundentes. Una vez esto se extrajeron testigos de hormigón de zonas sanas (nervios del tablero), para realizar en laboratorio los mismos ensayos acelerados de hielo-deshielo y de caracterización, de la segunda campaña, basados en la misma norma. De los resultados obtenidos se concluye que cuando se emplean sales fundentes se acelera de forma significativa el deterioro, aumentando tanto el contenido de agua en los poros como el gradiente generado (mecanismo de deterioro físico). Las sales de deshielo aceleran claramente la aparición del daño, que se incrementa incluso en un factor de 5 según se constata en esta investigación para los hormigones ensayados. Pero además se produce un gradiente de cloruros que se ha detectado tanto en los hormigones diseñados en laboratorio como en los extraídos de puentes existentes. En casi todos los casos han aparecido cambios en la microestructura de la pasta de cemento (mecanismo de deterioro químico), confirmándose la formación de un compuesto en el gel CSH de la pasta de cemento, del tipo Ca2SiO3Cl2, que posiblemente está contribuyendo a la alteración de la pasta y a la aceleración de los daños en presencia de sales fundentes. Existe un periodo entre la aparición de fisuración y la pérdida de masa. Las fisuras progresan rápidamente desde la interfase de los áridos más pequeños y angulosos, facilitando así el deterioro del hormigón. Se puede deducir así que el tipo de árido afecta al deterioro. En el caso de los testigos con recubrimiento asfáltico, parece haberse demostrado que la precipitación de sales genera tensiones en las zonas de hormigón cercanas al recubrimiento, que terminan por fisurar el material. Y se constata que el mecanimo de deterioro químico, probablemente tenga más repercusión que el físico, por cuanto el recubrimiento asfáltico es capaz de retener suficiente agua, como para que el gradiente de contenido de agua en el hormigón sea mucho menor que sin el recubrimiento. Se constató, sin embargo, la importancia del gradiente de cloruros en el hormigon. Por lo que se deduce que si bien el recubrimiento asfáltico es ciertamente protector frente a los ciclos H/D, su protección disminuye en presencia de sales; es decir, los cloruros acabarán afectando al hormigón del tablero del puente. Finalmente, entre los hormigones recientes y los antiguos extraídos de puentes reales, se observa que existen diferencias significativas en cuanto a la resistencia a los ciclos H/D entre ellos. Los hormigones más recientes resultan, a igualdad de propiedades, más resistentes tanto a ciclos de H/D en agua como en sales. Posiblemente el hecho de que los hormigones de los puentes hayan estado expuestos a condiciones de temperaturas extremas durante largos periodos de tiempo les ha sensibilizado. La tesis realizada, junto con nuevos contrastes que se realicen en el futuro, nos permitirá implementar una metodología basada en la extracción de testigos de tableros de puente reales para someterlos a ensayos de hielo-deshielo, basados en la norma europea UNECEN/ TS 12390-9 aunque con probetas no normalizadas para el mismo, y, a su vez, realizar sobre estas probetas otros ensayos de caracterización destructivos, que posibilitarán evaluar los daños ocasionados por este fenómeno y su evolución temporal, para actuar consecuentemente priorizando intervenciones de impermeabilización y reparación en el parque de puentes de la RCE. Incluso será posible la elaboración de mapas de riesgo, en función de las zonas de climatología más desfavorable y de los tratamientos de vialidad invernal que se lleven a cabo. Concrete damage by freeze-thaw cycles in the presence of melting salts frequently causes problems on bridges and infrastructures in European countries. Damage caused by freeze-thaw cycles in the concrete can be internal, essentially cracking and / or external as flaking (surface weathering due to environmental action). The peninsular Spain presents specific climatic and geographical characteristics. 18% of the surface has a height greater than 1,000 m and the geographical average height from the sea level is 660 m (being the second most mountainous country in Europe). This makes the National Road Network affected during certain periods due to adverse weather, particularly snow and ice, which can compromise road conditions for vehicular traffic. For this reason the National Road Authority performs works annually (Winter Road Campaign, along 6 months) to maintain the viability of the roads when they are affected by these phenomena. There are protocols and operational plans that allow systematize these maintenance jobs, that also have intensified in the last 10 years, and which are based on the use of deicing salts, mainly NaCl, with the mission that no ice sheets, or snow appear on the roads. In areas of strong thermal cycling, which in Spain are located in the central area of the Pyrenees, part of the Cantabrian coast and Central System, significant deterioration take place in the structures and wall surfaces of concrete due to freeze-thaw. But also the use of deicing salts for winter maintenance greatly accelerated the development of such damages. The concrete decks for road bridges about 40-50 years old, lack generally a waterproofing system, and are often formed by a pavement of asphalt, an adhesive emulsion and concrete slab. In this thesis the research going on aims to reproduce in the laboratory the processes taking place in the concrete of an existing deck at road bridges, about 40-50 years old, they are exposed for long periods to icing salt, to be performed in order to facilitate winter maintenance, and drastic temperature changes (freezing and thawing). Therefore four campaigns of research were conducted, considering that while we rely on the European standard UNE-CEN/TS 12390-9 "Testing hardened concrete. Freezethaw resistance. Mass loss", nonstandard specimens were fabricated for this test, actually conceived to determine the affection of the cycles only to the mass loss. Dimensions of the samples were in our case 150x300 mm, 75 x 150mm (standard cylindrical specimens for compression fractures UNE-EN 12390-3) and 286x76x76 (standard prismatic specimens to study volume change ASTM C157), which allowed us to carry on same samples more trials, as presented in the thesis, and especially to compare the results with similar sized samples taken from real bridges. In the first campaign, by application of that European standard, freeze-thaw cycles, with and without contact with deicing salt (NaCl 3% solution in compliance with such standard) were performed. Concrete made in the laboratory, trying to simulate the old bridges, provided a compressive strength of 22.6 MPa and water/cement ratio of 0.65. In this activity, the concrete specimens produced were subjected to aggressive freeze/thaw using a maximum temperature of +20ºC and a minimum temperature of - 20°C in order to be able to determine the sensitivity of this test to the concrete and specimens fabricated. This campaign had a second phase to go deeper into the behavior of the specimens subjected to cycled freeze/thaw in the presence of salts. In the second campaign, conducted on similar concrete specimens manufactured in laboratory, temperatures of +20ºC and -14ºC were used in the tests, which allowed us to analyze the deterioration process in more detail (performing a series of non-destructive testing and other destructive characterization, validating its application to the detection of the damage caused after the accelerated freeze-thaw tests, and also by applying electron microscopy techniques). The third campaign was conducted on concrete specimens similar to the above manufactured in laboratory, both cylindrical and prismatic, which was applied on one side a 4 cm asphalt coating, consisting of a real asphalt mixture, on a bituminous primer (for simulate the level of waterproofing that produces a pavement on the bridge deck). The fourth campaign was developed after careful selection of two concrete bridges 40- 50 years old, exposed and sensitive to freeze-thaw damage, in roads with input of melting salts. Concrete cores were extracted from healthy areas, for the same accelerated laboratory freeze-thaw testing and characterization made for the second campaign, based on the same standard. From the results obtained it is concluded that when melting salts are employed deterioration accelerates significantly, thus increasing the water content in the pores, as the gradient. Besides, chloride gradient was detected both in the concrete designed in the laboratory and in the extracted in existing bridges. In all cases there have been changes in the microstructure of the cement paste, confirming the formation of a compound gel CSH of the cement paste, Ca2SiO3Cl2 type, which is possibly contributing to impair the cement paste and accelerating the damage in the presence of melting salts. The detailed study has demonstrated that the formation of new compounds can cause porosity at certain times of the cycles may decrease, paradoxically, as the new compound fills the pores, although this phenomenon does not stop the deterioration mechanism and impairments increase with the number of cycles. There is a period between the occurrence of cracking and mass loss. Cracks progress rapidly from the interface of the smallest and angular aggregate, thus facilitating the deterioration of concrete. It can be deduced so the aggregate type affects the deterioration. The presence of melting salts in the system clearly accelerates the onset of damage, which increases even by a factor of 5 as can be seen in this investigation for concrete tested. In the case of specimens with asphalt coating, it seems to have demonstrated that the precipitation of salts generate tensions in the areas close to the concrete coating that end up cracking the material. It follows that while the asphalt coating is certainly a protection against the freeze/thaw cycles, this protection decreases in the presence of salts; so the chlorides will finally affect the concrete bridge deck. Finally, among the recent concrete specimens and the old ones extracted from real bridges, it is observed that the mechanical strengths are very similar to each other, as well as the porosity values and the accumulation capacity after pore water saturation. However, there are significant differences in resistance to freeze/thaw cycles between them. More recent concrete are at equal properties more resistant both cycles freeze/thaw in water with or without salts. Possibly the fact that concrete bridges have been exposed to extreme temperatures for long periods of time has sensitized them. The study, along with new contrasts that occur in the future, allow us to implement a methodology based on the extraction of cores from the deck of real bridges for submission to freeze-thaw tests based on the European standard UNE-CEN/TS 12390-9 even with non-standard specimens for it, and in turn, performed on these samples other destructive characterization tests, which will enable to assess the damage caused by this phenomenon and its evolution, to act rightly prioritizing interventions improving the waterproofing and other repairs in the bridge stock of the National Road Network. It will even be possible to develop risk maps, depending on the worst weather areas and winter road treatments to be carried out.