Dimensionless wave height parameter for preliminary design of scour protection in offshore wind farms

This article describes the results of an investigation aimed at the analysis methods used in the design of the protections against scour phenomenon on offshore wind farms in transitional waters, using medium and large diameter monopile type deep foundations.

Investigaciones dendrogeomorfológicas aplicadas a la gestión de los impactos por erosión hídrica acelerada de suelos en las sendas del parque nacional de Monfragüe

En muchos espacios naturales protegidos, el flujo peatonal de visitantes se concentra en determinados sectores del área de uso público, sobre todo en la proximidad de las principales vías de acceso (carreteras, núcleos de población...) y en un reducido número de sendas y caminos peatonales que comunican los elementos más visitados. Es el caso del camino hacia la Cola de Caballo en el parque nacional de Ordesa y Monte Perdido; el camino a la ermita de San Frutos en el parque natural de las Hoces del río Duratón; o la senda que comunica el Salto del Gitano con el castillo y la ermita en el parque nacional de Monfragüe, por citar algunos ejemplos. Esta concentración de actividades de senderismo produce en determinados tramos de estos caminos y sendas (zonas con suelos arenosos o limosos y altas pendientes) una erosión hídrica acelerada por el efecto físico del pisoteo, compactación y continua fricción. En ocasiones se llegan a formar regueros, pequeños barrancos y se pierden grandes cantidades de suelos fértiles, que además fosilizan y aterran aquéllas zonas donde va a parar la escorrentía, produciendo importantes impactos en estos espacios singulares. Existen numerosos ejemplos de ingentes partidas económicas que los gestores de estos espacios protegidos tienen que destinar a la reparación y recuperación de estas sendas y su entorno. Para ayudar a los gestores es básico disponer de metodologías y herramientas que cuantifiquen esta erosión hídrica (en mm/año) delimitando qué tramos de estas sendas y caminos tienen los mayores problemas erosivos, para así determinar cuáles deben ser prioritarios en su corrección, o qué acciones de restricción de paso o determinación de capacidad de acogida, son necesarias adoptar. Para esta cuantificación son muy útiles, desde hace décadas, las técnicas dendrogeomorfológicas aplicadas a las raíces de árboles que han quedado expuestas a la intemperie por la erosión acelerada en las sendas. En este trabajo se propone una nueva metodología de medición del suelo denudado en relación con la raíz, basado en el estudio microtopográfico de la superficie utilizando moldes y réplicas de alta resolución realizados en diferentes tipos de siliconas, latex y escayolas, y su posterior escaneo tridimensional. La zona piloto donde se ha ensayado esta metodología son los senderos y caminos del parque nacional de Monfragüe (Cáceres), que presentan raíces expuestas debido a la intensa erosión hídrica acelerada como consecuencia de la elevada concentración de visitantes. Los estudios son financiados por el proyecto de investigación IDEA-GesPPNN, del OAPN (MAGRAMA).

Secundary school profile in science and technology versus the first year at the Technical University of Madrid. Cause of failure or quitting?

Se analiza el absentismo, el fallo y el abandono de los estudiantes en los primeros semestres del grado sobre la base de su formación en la educación secundaria.

Ingeniería Forestal y ambiental en medios insulares

Las Islas Canarias a pesar de su reducida extensión y del relativo poco peso específico a nivel mundial, no es ajena a los problemas globales detectados en la conservación de bosques y en la importancia que éstos tienen para obtener beneficios económicos, socioculturales y ambientales. La gestión forestal sostenible es en este sentido esencial para asegurar y compatibilizar los diversos beneficios del bosque. El papel específico de los bosques y su gestión son sin embargo temas aún por conocer en nuestras islas, por lo que el Año Internacional de los Bosques ha representado una oportunidad única para dar a conocer el mundo forestal y acercarlo a nuestra sociedad. El presente libro consta de 25 capítulos donde se ha contemplado la mayoría de los aspectos a tener en cuenta en la planificación y gestión del medio forestal y natural. Desde la historia forestal del archipiélago, hasta el uso y técnicas de manejo de los recursos naturales, incluyendo el agua, la energía en forma de biomasa y la selvicultura.

Monitorización y seguimiento del esfuerzo realizado por los estudiantes y de su asistencia a actividades presenciales

Este artículo documenta el planteamiento, la metodología y los primeros resultados de un plan de monitorización detallada del esfuerzo y de asistencia a actividades presenciales por parte de los estudiantes de las titulaciones ofertadas por la Escuela Técnica Superior de Ingenieros Navales de la Universidad Politécnica de Madrid durante el segundo cuatrimestre del curso 2011-2012. Se ha establecido un sistema mecánico de recogida de datos de esfuerzo por parte de los estudiantes utilizando una hoja tipo test especialmente configurada al efecto. Se pasa una hoja en todas y cada una de las actividades presenciales realizadas y en la hoja se solicita información sobre el trabajo "fuera de clase". Se documenta en este artículo cómo se ha estructurado esa hoja, qué tipo de datos se recogen, cómo se tratan mediante una base de datos creada al efecto, qué tipo de análisis se puede realizar y qué resultados preliminares obtenemos de dichos análisis.

Generación procedimental de contenidos en videojuegos

Este proyecto consiste en el desarrollo de un sistema completo de generación procedimental de misiones para videojuegos. Buscamos crear, mediante un encadenamiento de algoritmos y un modelado del juego y sus componentes, secuencias de acciones y eventos de juego encadenados entre sí de forma lógica. La realización de estas secuencias de acciones lleva progresivamente hacia un objetivo final. Estas secuencias se conocen en el mundo de los juegos como misiones. Las dos fases principales del proceso son la generación de una misión a partir de un estado de juego inicial y la búsqueda de una misión óptima utilizando ciertos criterios que pueden estar ligados a las propiedades del jugador, dando lugar a misiones adaptativas. El proyecto contempla el desarrollo íntegro del sistema, lo que incluye tanto el sistema de generación y búsqueda como un videojuego donde integrar el resto del sistema para completarlo. El resultado final es plenamente funcional y jugable. La base teórica del proyecto proviene de la simbiosis de dos artes: la generación procedimental de contenido y la narración interactiva. This project involves the development of a complete procedural game quest generation system. We seek to build, by linking a series of algorithms, game and game component models, sequences of logically chained game actions and events. The ordered accomplishment of these sequences lead progressively to the fulfillment of a final objective. These sequences are known as quests in the videogame world. The two main parts of the process are quest generation from an initial game state and optimal quest search. This last is achieved by using certain criteria that can defined by the player properties, thus giving birth to adaptive quests. In this project. The system is comprehensively developed, including the quest generation and optimal search, as well as a full videogame, in which the rest of the system will be embedded so as to complete it. The final result is fully functional and playable. The theoretical basis of the project comes from the symbiosis of two different arts: procedural content generation and interactive storytelling.

Storm evolution characterization for analysing stone armour damage progression

Storm evolution is fundamental for analysing the damage progression of the different failure modes and establishing suitable protocols for maintaining and optimally sizing structures. However, this aspect has hardly been studied and practically the whole of the studies dealing with the subject adopt the Equivalent triangle storm. As against this approach, two new ones are proposed. The first is the Equivalent Triangle Magnitude Storm model (ETMS), whose base, the triangular storm duration, D, is established such that its magnitude (area describing the storm history above the reference threshold level which sets the storm condition),HT, equals the real storm magnitude. The other is the Equivalent Triangle Number of Waves Storm (ETNWS), where the base is referred in terms of the real storm's number of waves,Nz. Three approaches are used for estimating the mean period, Tm, associated to each of the sea states defining the storm evolution, which is necessary to determine the full energy flux withstood by the structure in the course of the extreme event. Two are based on the Jonswap spectrum representativity and the other uses the bivariate Gumbel copula (Hs, Tm), resulting from adjusting the storm peaks. The representativity of the approaches proposed and those defined in specialised literature are analysed by comparing the main armour layer's progressive loss of hydraulic stability caused by real storms and that relating to theoretical ones. An empirical maximum energy flux model is used for this purpose. The agreement between the empirical and theoretical results demonstrates that the representativity of the different approaches depends on the storm characteristics and point towards a need to investigate other geometrical shapes to characterise the storm evolution associated with sea states heavily influenced by swell wave components.

Use of a scrapped ship as a floating breakwater for shore protection

The purpose of this research is to assess the effectiveness of a ship used as a detached floating breakwater for coastal protection and forming salients of sand or tombolos. Floating breakwaters have been extensively used as port or coastal protection structures and display advantages in terms of construction and ecology, amongst others. However, the greatest problem these structures present is the limited range of wave heights and periods for which they are really effective. Furthermore, ships may be considered as floating structures which, used as breakwaters, would keep the advantages of floating breakwaters and would increase their range of applicability. The possibility of using ships at the conclusion of their useful life for this purpose would also involve greater economic and environmental advantages. Tests were carried out to assess the ship’s effectiveness as a detached floating breakwater using a scaled down physical model to determine the vessel’s transmission coefficient (Kt) as to regular waves with significant periods of 5 sec to 12 sec and significant wave heights of 1.5 m to 4 m at depths from 20 m to 35 m. The ship proves effective for waves up to 4 m significant height and significant periods up to 9 sec. Hanson and Kraus and Pilarzyk’s analytical models, which take transmission coefficients into account, were used to analyse the shore’s response to the breakwater protection. The results obtained show that salients form for waves with periods between 6 sec and 9 sec. It is also concluded that the depths tested are far different from the more usual shallow water involved in constructing detached breakwaters and the shore’s response is therefore scarce.

Storm characterization for analyzing stone armour damage progression

Storm evolution is fundamental for analysing the damage progression of the different failure modes and establishing suitable protocols for maintaining and optimally sizing structures. However, this aspect has hardly been studied and practically the whole of the studies dealing with the subject adopt the Equivalent triangle storm. As against this approach, two new ones are proposed. The first is the Equivalent Triangle Magnitude Storm model (ETMS), whose base, the triangular storm duration, D, is established such that its magnitude (area describing the storm history above the reference threshold level which sets the storm condition),HT, equals the real storm magnitude. The other is the Equivalent Triangle Number of Waves Storm (ETNWS), where the base is referred in terms of the real storm's number of waves,Nz. Three approaches are used for estimating the mean period, Tm, associated to each of the sea states defining the storm evolution, which is necessary to determine the full energy flux withstood by the structure in the course of the extreme event. Two are based on the Jonswap spectrum representativity and the other uses the bivariate Gumbel copula (Hs, Tm), resulting from adjusting the storm peaks. The representativity of the approaches proposed and those defined in specialised literature are analysed by comparing the main armour layer's progressive loss of hydraulic stability caused by real storms and that relating to theoretical ones. An empirical maximum energy flux model is used for this purpose. The agreement between the empirical and theoretical results demonstrates that the representativity of the different approaches depends on the storm characteristics and point towards a need to investigate other geometrical shapes to characterise the storm evolution associated with sea states heavily influenced by swell wave components.

Cover cracking of the reinforced concrete due to rebar corrosion induced by chloride penetration

This paper is focused on the problem of the chloride-induced corrosion of the rebar in reinforced concrete, with special application to the slabs and decks of the bridges. High superficial concentrations may be usual in these structures (marine environments or de-icing salts in roadway bridges, e.g.). Like any aggressive agent such as water, gases or other dissolved ions, chloride induced deterioration is very conditioned by possibilities of transport through concrete mass.

Cover cracking of the reinforced concrete due to rebar corrosion induced by chloride penetration

Este artículo estudia el proceso de fisuración del hormigón por corrosión de la armadura. Se presenta un modelo de transporte de cloruros en el hormigón, que contempla la no-linealidad de los coeficientes de difusión, las isotermas de absorción y el fenómeno de convección. A partir de los resultados de penetración de cloruros, se establece la corrosión de la armadura con la consiguiente expansión radial. La fisuración del hormigón se estudia con un modelo de fisura embebida. Los dos modelos (iniciación y propagación) se incorporan en un programa de elementos finitos. El modelo se contrasta con resultados experimentales, obteniéndose un buen ajuste. Una de las dificultades es establecer el umbral de concentración de cloruros que da lugar al inicio de la corrosión de la armadura.This paper is focused on the chloride-induced corrosion of the rebar in RC. A comprehensive model for the chloride ingress into concrete is presented, with special attention to non-linear diffusion coefficients, chloride binding isotherms and convection phenomena. Based on the results of chloride diffusion, subsequent active corrosion is assumed and the radial expansion of the corroded reinforcement reproduced. For cracking simulation, the Strong Discontinuity Approach is applied. Both models (initiation and propagation corrosion stages) are incorporated in the same finite element program and chained. Comparisons with experimental results are carried out, with reasonably good agreements being obtained, especially for cracking patterns. Major limitations refer to difficulties to establish precise levels of basic data such as the chloride ion content at concrete surface, the chloride threshold concentration that triggers active corrosion, the rate of oxide production or the rust mechanical properties.

Analysis of wave attenuation and shore protection of a bulk carrier ship performing as a detached floating breakwater

Análisis de la atenuación del oleaje por un carguero funcionando como dique flotante y aplicación a dos casos de protección portuaria y costera. The effectiveness of a bulk carrier working as a detached floating breakwater to protect a stretch of coast and form salients or tombolos is assessed in this paper. Experiments were conducted in the Madrid CEDEX facilities in a 30 m long, 3 m wide, 1/150 scale flume. The bulk carrier ship is 205 m long, 29 m wide and 18 m in height with a draught of 13 m, and has been subjected to irregular waves with significant heights from 2 m to 4 m and peak periods from 6 s to 12 s at a depth of 15 m, all prototype dimensions. Three probes were placed between the wave paddle and the ship to record incident and reflected waves and four probes were placed between the ship and the coastline to measure the transmitted waves. Transmission, reflection and dissipation coefficients (Ct, Cr, Cd) were calculated to determine wave attenuation. Results show good shelter in the lee of the ship with values of Ct under 0.5 for peak periods from 6 s to 11 s. In addition, forces on the mooring chains were measured showing maximum values of about 2000 tons at a 10 speak period. Finally, two analytical models were used to determine the shoreline’s response to the ship’s protection and to assess the possible forming of salients or tombolos. According to the results, salients - but not tombolos - are formed in all tests.

Estudio geológico preliminar y reconstrucción paleoambiental de la cuenca endorreica de "El Hito" (Cuenca)

Mediante técnicas geofísicas (S.E.V.) y la caracterización hidroquímica de las aguas (determinación de aniones predominantes), se han obtenido datos sobre la estratigrafía y el funcionamiento de la Laguna efímera de El Hito (Cuenca), situada sobre yesos, y próxima al vecino emplazamiento del Almacén Temporal Centralizado (ATC) en Villar de Cañas. Asimismo, a partir del estudio del registro sedimentario de un sondeo manual en el que se recogieron muestras en las que se determinaron los compuestos orgánicos se realizó la reconstrucción de las condiciones paleoambientales. ABSTRACT Through geophysics techniques like vertical and electrical drillings, and hydrochemistry characterization of the waters (development of main anions), it has been obtained some data related to the stratigraphy and performance of the ephemeral lake in “El Hito”, Cuenca, Spain. El Hito´s lake is placed on a basin of plasters and it is next to site of the Centralized Temporary Storage in Villar de Cañas, Cuenca, Spain. Additionally, manual drillings will be conducted by collecting samples to determine the organic compounds in order to carry out a reconstruction of the paleoenvironmental conditions.

The effect of scour protections in offshore wind farms

The installation of offshore scour protection systems in offshore wind farms allows avoid the effect of scour phenomenon around these structures. Up to date, numerous research projects have been carried out to justify the necessity of the scour protection systems and also to optimize their design. Protection systems based on riprap is frequently used due to its low cost and easy availability compared to other solutions such as geotextile bags or prefabricated concrete blocks. The sizing of these structures can be performed according to a series of recommendations that can optimize the costs associated with them, but there have been only few studies with real data up to now which have allowed identify the need for such protections. This investigation aims to assess the functionality of the scour protections adopted through the available data about their characteristics and the scour depth developed around the foundations. In this sense, this paper presents the results of a study that analyzes the functionality of scour protections in different European offshore wind farms.

An analysis of recent changes in Spanish Coastal Law

Spanish coastal legislation has changed in response to changing circumstances. The objective of the 1969 Spanish Coastal Law was to assign responsibilities in the Public Domain to the authorities. The 1980 Spanish Coastal Law addressed infractions and sanctions issues. The 1988 Spanish Coastal Law completed the responsibilities and sanctions aspects and included others related to the delimitation of the Public Domain, the private properties close to the Public Domain, and limitations on landuse in this area. The 1988 Spanish Coastal Law has been controversial since its publication. The “European Parliament Report on the impact of extensive urbanization in Spain on individual rights of European citizen, on the environment and on the application of EU law, based upon petitions received”, published in 2009 recommended that the Spanish Authorities make an urgent revision of the Coastal Law with the main objective of protecting property owners whose buildings do not have negative effects on the coastal environment. The revision recommended has been carried out, in the new Spanish Coastal Law “Ley 2/2013, de 29 de mayo, de protección y uso sostenible del litoral y de modificación de la Ley 22/1988, de 28 de Julio, de Costas”, published in May of 2013. This is the first major change in the 25 years since the previous 1988 Spanish Coastal Law. This paper compares the 1988 and 2013 Spanish Coastal Law documents, highlighting the most important issues like the Public Domain description, limitations in private properties close to the Public Domain limit, climate change influence, authorizations length, etc. The paper includes proposals for further improvements.