Effectiveness for Ddtecting faults within and outside the scope of testing techniques: an independent replication

The verification and validation activity plays a fundamental role in improving software quality. Determining which the most effective techniques for carrying out this activity are has been an aspiration of experimental software engineering researchers for years. This paper reports a controlled experiment evaluating the effectiveness of two unit testing techniques (the functional testing technique known as equivalence partitioning (EP) and the control-flow structural testing technique known as branch testing (BT)). This experiment is a literal replication of Juristo et al. (2013).Both experiments serve the purpose of determining whether the effectiveness of BT and EP varies depending on whether or not the faults are visible for the technique (InScope or OutScope, respectively). We have used the materials, design and procedures of the original experiment, but in order to adapt the experiment to the context we have: (1) reduced the number of studied techniques from 3 to 2; (2) assigned subjects to experimental groups by means of stratified randomization to balance the influence of programming experience; (3) localized the experimental materials and (4) adapted the training duration. We ran the replication at the Escuela Politécnica del Ejército Sede Latacunga (ESPEL) as part of a software verification & validation course. The experimental subjects were 23 master?s degree students. EP is more effective than BT at detecting InScope faults. The session/program andgroup variables are found to have significant effects. BT is more effective than EP at detecting OutScope faults. The session/program and group variables have no effect in this case. The results of the replication and the original experiment are similar with respect to testing techniques. There are some inconsistencies with respect to the group factor. They can be explained by small sample effects. The results for the session/program factor are inconsistent for InScope faults.We believe that these differences are due to a combination of the fatigue effect and a technique x program interaction. Although we were able to reproduce the main effects, the changes to the design of the original experiment make it impossible to identify the causes of the discrepancies for sure. We believe that further replications closely resembling the original experiment should be conducted to improve our understanding of the phenomena under study.

Drifting plasma collection by a positive biased tether wire in LEO-like plasma conditions: current measurement and plasma diagnostic

BETs is a three-year project financed by the Space Program of the European Commission, aimed at developing an efficient deorbit system that could be carried on board any future satellite launched into Low Earth Orbit (LEO). The operational system involves a conductive tape-tether left bare to establish anodic contact with the ambient plasma as a giant Langmuir probe. As a part of this project, we are carrying out both numerical and experimental approaches to estimate the collected current by the positive part of the tether. This paper deals with experimental measurements performed in the IONospheric Atmosphere Simulator (JONAS) plasma chamber of the Onera-Space Environment Department. The JONAS facility is a 9- m3 vacuum chamber equipped with a plasma source providing drifting plasma simulating LEO conditions in terms of density and temperature. A thin metallic cylinder, simulating the tether, is set inside the chamber and polarized up to 1000 V. The Earth's magnetic field is neutralized inside the chamber. In a first time, tether collected current versus tether polarization is measured for different plasma source energies and densities. In complement, several types of Langmuir probes are used at the same location to allow the extraction of both ion densities and electron parameters by computer modeling (classical Langmuir probe characteristics are not accurate enough in the present situation). These two measurements permit estimation of the discrepancies between the theoretical collection laws, orbital motion limited law in particular, and the experimental data in LEO-like conditions without magnetic fields. In a second time, the spatial variations and the time evolutions of the plasma properties around the tether are investigated. Spherical and emissive Langmuir probes are also used for a more extensive characterization of the plasma in space and time dependent analysis. Results show the ion depletion because of the wake effect and the accumulation of- ions upstream of the tether. In some regimes (at large positive potential), oscillations are observed on the tether collected current and on Langmuir probe collected current in specific sites.

Towards an Optimal Implementation of Cascade

Cascade is an information reconciliation protocol proposed in the context of secret key agreement in quantum cryptography. This protocol allows removing discrepancies in two partially correlated sequences that belong to distant parties, connected through a public noiseless channel. It is highly interactive, thus requiring a large number of channel communications between the parties to proceed and, although its efficiency is not optimal, it has become the de-facto standard for practical implementations of information reconciliation in quantum key distribution. The aim of this work is to analyze the performance of Cascade, to discuss its strengths, weaknesses and optimization possibilities, comparing with some of the modified versions that have been proposed in the literature. When looking at all design trade-offs, a new view emerges that allows to put forward a number of guidelines and propose near optimal parameters for the practical implementation of Cascade improving performance significantly in comparison with all previous proposals.

Demystifying the information reconciliation protocol cascade

Cascade is an information reconciliation protocol proposed in the context of secret key agreement in quantum cryptography. This protocol allows removing discrepancies in two partially correlated sequences that belong to distant parties, connected through a public noiseless channel. It is highly interactive, thus requiring a large number of channel communications between the parties to proceed and, although its efficiency is not optimal, it has become the de-facto standard for practical implementations of information reconciliation in quantum key distribution. The aim of this work is to analyze the performance of Cascade, to discuss its strengths, weaknesses and optimization possibilities, comparing with some of the modified versions that have been proposed in the literature. When looking at all design trade-offs, a new view emerges that allows to put forward a number of guidelines and propose near optimal parameters for the practical implementation of Cascade improving performance significantly in comparison with all previous proposals.

Validation of the burn-up code EVOLCODE 2.0 with PWR experimental data and with a Sensitivity/Uncertainty analysis

A validation of the burn-up simulation system EVOLCODE 2.0 is presented here, involving the experimental measurement of U and Pu isotopes and some fission fragments production ratios after a burn-up of around 30 GWd/tU in a Pressurized Light Water Reactor (PWR). This work provides an in-depth analysis of the validation results, including the possible sources of the uncertainties. An uncertainty analysis based on the sensitivity methodology has been also performed, providing the uncertainties in the isotopic content propagated from the cross sections uncertainties. An improvement of the classical Sensitivity/ Uncertainty (S/U) model has been developed to take into account the implicit dependence of the neutron flux normalization, that is, the effect of the constant power of the reactor. The improved S/U methodology, neglected in this kind of studies, has proven to be an important contribution to the explanation of some simulation-experiment discrepancies for which, in general, the cross section uncertainties are, for the most relevant actinides, an important contributor to the simulation uncertainties, of the same order of magnitude and sometimes even larger than the experimental uncertainties and the experiment- simulation differences. Additionally, some hints for the improvement of the JEFF3.1.1 fission yield library and for the correction of some errata in the experimental data are presented.

La planificación estratégica en los procesos de conformación de las ciudades globales: Los casos de Singapur y Dubái

La globalización, en las últimas décadas, ha tenido una amplia repercusión e influencia sobre la evolución de los procesos que intervienen en la gestión y la ordenación urbano-territorial. Esta influencia ha sido especialmente destacable en los procesos de conformación de las Ciudades Globales (CG). No obstante, dentro de los procesos actuales, y de los ya iniciados décadas atrás, se encuentran discordancias tanto con respecto a los modelos de gestión urbanoterritoriales como con relación a los procesos de conformación de las CG. Esto es debido a que cada territorio o CG no ha seguido un proceso homogéneo; sino que, a través del modelo empresarial de la “Planificación Estratégica” (PE) cada proceso ha sido adaptado para poder atender y potenciar las características más singulares de cada territorio, y de esta forma, poder alcanzar las ambiciosas posiciones de liderazgo. Por este motivo, el éxito de la PE se ha basado en simplificar la complejidad de los modelos y agentes que participan en los procesos de conformación de los territorios y ciudades globales. En esta investigación se propone analizar el valor de la PE como proceso de gestión y ordenación urbano-territorial; al igual que se pretende esclarecer tanto los modelos como los elementos de los que se compone. Para, poder así, identificar las relaciones que se producen entre los modelos y elementos principales de los que se compone una PE. Por motivos relacionados con la necesaria acotación de toda investigación, y mediante el apoyo de tanto el tutor de esta investigación como de expertos externos consultados, se ha acordado analizar los aspectos más característicos del proceso estratégico, como son: los territoriales, los económicos y los de gobernanza. Esta investigación se ha llevado a cabo a través del uso del método estudio de casos, mediante un proceso de recogida de información compuesto por dos estudios de campo, Singapur y Dubái, con similitudes tanto en el proceso como en los resultados. También se han realizado consultas a expertos multidisciplinares, cuya información y aportaciones se han articulado y procesado mediante la utilización del sistema de análisis de realidades complejas, presentado en el marco conceptual. Los resultados del estudio de los casos de Singapur y de Dubái muestran como las acciones urbano-territoriales que se han llevado a cabo en ambas ciudades y en sus territorios circundantes son consecuencia del uso de la planificación estratégica en beneficio de un mejor posicionamiento dentro del contexto global. De esta forma, mediante el análisis de las asimetrías y de las relaciones existentes entre el proceso, los casos de estudio y el contexto global, se identifica y se esclarece los términos relacionados con las ciudades globales referentes, consolidadas y emergentes. A su vez, a lo largo del marco conceptual se correlaciona y esclarece los procesos territoriales, económicos y de gobernanza, identificando las responsabilidades entre las instituciones, los organismos, los agentes y los actores (tanto públicos como privados) que inician y gestionan tanto el plan estratégico como los procesos derivados de él. Para finalizar, el análisis cruzado de los resultados demuestra la relación existente entre la planificación estratégica, la ordenación urbano-territorial, la gestión económica y la gobernanza. Pudiéndose identifican las asimetrías producidas durante la implantación de un plan estratégico, de forma que, tras un análisis del sistema de realidades complejas, estas asimetrías puedan ser solventadas. RESUMO Nas últimas décadas, a globalização tem tido um grande impacto sobre a evolução dos processos de gestão e planejamento urbano-territorial. Essa influência foi particularmente notável nos processos de formação das cidades globais (CG). No entanto, comparando os processos atuais e aqueles iniciados há décadas, as discrepâncias são encontradas tanto no que diz respeito aos modelos de uso do solo urbano, como em relação aos processos de formação e gestão das CG. Isso ocorre porque cada território ou CG não tem seguido um processo uniforme; mas, por meio do modelo de negócios de "Planejamento Estratégico" (PE) cada processo foi adaptado para servir e melhorar as características mais singulares de cada território para alcançar posições de liderança global. Portanto, o sucesso do PE é baseado na simplificação da complexidade dos modelos e atores envolvidos nos processos de formação dos territórios e das cidades globais. Esta pesquisa tem como objetivo analisar o valor do PE como um processo de gestão territorial e urbana; como também esclarecer os modelos e elementos do PE estudados. Para, então, poder identificar as relações que ocorrem entre os modelos e os principais elementos integrantes de um PE. Como recorte de pesquisa, após consultas com o tutor da pesquisa e com outros pesquisadores especialistas, decidiu-se analisar os aspectos mais característicos do processo estratégico, sendo eles: os territoriais, os econômicos e os de governabilidade. Esta pesquisa ’e um estudo de casos. Para realizá-lo, foram escolhidos dois estudos de campo (Dubai e Cingapura) e além de consultas com especialistas multidisciplinares, cujas informações e colaborações foram analisadas por um sistema de analise de realidades complexas, explicado na parte conceitual dessa tese. Os resultados do estudo dos casos de Dubai e Cingapura mostra como as ações urbanoterritoriais que foram realizadas em ambas cidades e em seus territórios circundantes são resultado do uso do planejamento estratégico em prol de uma melhor localização no contexto global. Assim, através da análise das assimetrias e da relação entre o processo, os estudos de caso e o contexto global, identifica-se e esclarece os termos relacionados com as cidades globais referentes, consolidadas e emergentes. Também, no arcabouço conceitual correlacionase e esclarecem-se os processos econômicos, territoriais e de governabilidade, identificando as responsabilidades das instituições, agências, agentes e atores (públicos e privados), que iniciam e gerenciam tanto o plano estratégico, como os processos derivados. A análise cruzada dos resultados demonstra a relação entre o planejamento estratégico, o planejamento urbano-territorial, a gestão econômica e a governabilidade. A pesquisa é capaz de identificar as assimetrias produzidas durante a implementação de um plano estratégico, para que depois da análise do sistema de realidades complexas, essas assimetrias possam ser resolvidas. ABSTRACT Globalization, in recent decades, has had a wide impact and influence on the evolution of the processes involved in the urban planning management. This influence has been particularly notable in the formation processes for the Global Cities (GC). However, within the current processes, even in those started decades ago, discrepancies are found between the urbanterritorial models and their relation to the processes of formation for the CG. This is because each territory, or CG, has not followed a uniform process; although, each process has been adapted through the business model of the "Strategic Planning" (SP) to serve and enhance the most unique characteristics of each urban territory, until reaching the ambitious global leadership positions. Therefore, the success of SP is based on simplifying the complexity of the models and actors involved in the processes of formation of the GCs and territories. This research aims to analyze the value of SP as a process for the urban and territorial management; intended to clarify both models and elements of which it is composed. And, for so, identify the relationships that occur between them. For reasons related to the required limits of all research, and through the support of this research by both the tutor and the consulted outside experts, has agreed to analyze the most characteristic aspects of the strategic process, which are: territory, economy and governance. This research was conducted through the use of the case study methodology; by a process of information collection of two field studies, Singapore and Dubai, with similarities in both the process and the results; and through consultation with a variety of multidisciplinary experts. Whose information and input has been articulated and processed by the use of a system prepared for the complex analysis of realities presented in the research’s conceptual framework. Thus, analyzing the asymmetries and relationship between the results of the study cases of Singapore and Dubai, have shown how the urban-territorial actions, which have been carried out in both cities and in their surrounding territories, are the result of the use of the strategic planning process for the benefit of a better position with respect to the global context. Meanwhile, along the conceptual framework correlates and clarifies the territorial, economic and governance processes, identifying responsibilities between the institutions, agencies, agents and actors (public and private) that initiate and manage both strategic planning and processes derived from it. Finally, the cross-analysis of the results shows the relationship between strategic planning, urban and territorial planning, economic management and governance. Being able to identify and eliminate the asymmetries produced during the implementation of a strategic planning for the formation of a Global City.

Effects of cross sections tables generation and optimization on rod ejection transient analyses

Best estimate analysis of rod ejection transients requires 3D kinetics core simulators. If they use cross sections libraries compiled in multidimensional tables,interpolation errors – originated when the core simulator computes the cross sections from the table values – are a source of uncertainty in k-effective calculations that should be accounted for. Those errors depend on the grid covering the domain of state variables and can be easily reduced, in contrast with other sources of uncertainties such as the ones due to nuclear data, by choosing an optimized grid distribution. The present paper assesses the impact of the grid structure on a PWR rod ejection transient analysis using the coupled neutron-kinetics/thermal-hydraulicsCOBAYA3/COBRA-TF system. Forthispurpose, the OECD/NEA PWR MOX/UO2 core transient benchmark has been chosen, as material compositions and geometries are available, allowing the use of lattice codes to generate libraries with different grid structures. Since a complete nodal cross-section library is also provided as part of the benchmark specifications, the effects of the library generation on transient behavior are also analyzed.Results showed large discrepancies when using the benchmark library and own-generated libraries when compared with benchmark participants’ solutions. The origin of the discrepancies was found to lie in the nodal cross sections provided in the benchmark.

Effectiveness for detecting faults within and outside the scope of testing techniques: an independent replication

The verification and validation activity plays a fundamental role in improving software quality. Determining which the most effective techniques for carrying out this activity are has been an aspiration of experimental software engineering researchers for years. This paper reports a controlled experiment evaluating the effectiveness of two unit testing techniques (the functional testing technique known as equivalence partitioning (EP) and the control-flow structural testing technique known as branch testing (BT)). This experiment is a literal replication of Juristo et al. (2013). Both experiments serve the purpose of determining whether the effectiveness of BT and EP varies depending on whether or not the faults are visible for the technique (InScope or OutScope, respectively). We have used the materials, design and procedures of the original experiment, but in order to adapt the experiment to the context we have: (1) reduced the number of studied techniques from 3 to 2; (2) assigned subjects to experimental groups by means of stratified randomization to balance the influence of programming experience; (3) localized the experimental materials and (4) adapted the training duration. We ran the replication at the Escuela Polite?cnica del Eje?rcito Sede Latacunga (ESPEL) as part of a software verification & validation course. The experimental subjects were 23 master?s degree students. EP is more effective than BT at detecting InScope faults. The session/program and group variables are found to have significant effects. BT is more effective than EP at detecting OutScope faults. The session/program and group variables have no effect in this case. The results of the replication and the original experiment are similar with respect to testing techniques. There are some inconsistencies with respect to the group factor. They can be explained by small sample effects. The results for the session/program factor are inconsistent for InScope faults. We believe that these differences are due to a combination of the fatigue effect and a technique x program interaction. Although we were able to reproduce the main effects, the changes to the design of the original experiment make it impossible to identify the causes of the discrepancies for sure. We believe that further replications closely resembling the original experiment should be conducted to improve our understanding of the phenomena under study.

A Semantic Approach to Problem-Based Learning with Conceptual Models

El aprendizaje basado en problemas se lleva aplicando con éxito durante las últimas tres décadas en un amplio rango de entornos de aprendizaje. Este enfoque educacional consiste en proponer problemas a los estudiantes de forma que puedan aprender sobre un dominio particular mediante el desarrollo de soluciones a dichos problemas. Si esto se aplica al modelado de conocimiento, y en particular al basado en Razonamiento Cualitativo, las soluciones a los problemas pasan a ser modelos que representan el compotamiento del sistema dinámico propuesto. Por lo tanto, la tarea del estudiante en este caso es acercar su modelo inicial (su primer intento de representar el sistema) a los modelos objetivo que proporcionan soluciones al problema, a la vez que adquieren conocimiento sobre el dominio durante el proceso. En esta tesis proponemos KaiSem, un método que usa tecnologías y recursos semánticos para guiar a los estudiantes durante el proceso de modelado, ayudándoles a adquirir tanto conocimiento como sea posible sin la directa supervisión de un profesor. Dado que tanto estudiantes como profesores crean sus modelos de forma independiente, estos tendrán diferentes terminologías y estructuras, dando lugar a un conjunto de modelos altamente heterogéneo. Para lidiar con tal heterogeneidad, proporcionamos una técnica de anclaje semántico para determinar, de forma automática, enlaces entre la terminología libre usada por los estudiantes y algunos vocabularios disponibles en la Web de Datos, facilitando con ello la interoperabilidad y posterior alineación de modelos. Por último, proporcionamos una técnica de feedback semántico para comparar los modelos ya alineados y generar feedback basado en las posibles discrepancias entre ellos. Este feedback es comunicado en forma de sugerencias individualizadas que el estudiante puede utilizar para acercar su modelo a los modelos objetivos en cuanto a su terminología y estructura se refiere. ABSTRACT Problem-based learning has been successfully applied over the last three decades to a diverse range of learning environments. This educational approach consists of posing problems to learners, so they can learn about a particular domain by developing solutions to them. When applied to conceptual modeling, and particularly to Qualitative Reasoning, the solutions to problems are models that represent the behavior of a dynamic system. Therefore, the learner's task is to move from their initial model, as their first attempt to represent the system, to the target models that provide solutions to that problem while acquiring domain knowledge in the process. In this thesis we propose KaiSem, a method for using semantic technologies and resources to scaffold the modeling process, helping the learners to acquire as much domain knowledge as possible without direct supervision from the teacher. Since learners and experts create their models independently, these will have different terminologies and structure, giving rise to a pool of models highly heterogeneous. To deal with such heterogeneity, we provide a semantic grounding technique to automatically determine links between the unrestricted terminology used by learners and some online vocabularies of the Web of Data, thus facilitating the interoperability and later alignment of the models. Lastly, we provide a semantic-based feedback technique to compare the aligned models and generate feedback based on the possible discrepancies. This feedback is communicated in the form of individualized suggestions, which can be used by the learner to bring their model closer in terminology and structure to the target models.

Rate-Adaptive LDPC-based key reconciliation for high performance quantum key distribution

The postprocessing or secret-key distillation process in quantum key distribution (QKD) mainly involves two well-known procedures: information reconciliation and privacy amplification. Information or key reconciliation has been customarily studied in terms of efficiency. During this, some information needs to be disclosed for reconciling discrepancies in the exchanged keys. The leakage of information is lower bounded by a theoretical limit, and is usually parameterized by the reconciliation efficiency (or inefficiency), i.e. the ratio of additional information disclosed over the Shannon limit. Most techniques for reconciling errors in QKD try to optimize this parameter. For instance, the well-known Cascade (probably the most widely used procedure for reconciling errors in QKD) was recently shown to have an average efficiency of 1.05 at the cost of a high interactivity (number of exchanged messages). Modern coding techniques, such as rate-adaptive low-density parity-check (LDPC) codes were also shown to achieve similar efficiency values exchanging only one message, or even better values with few interactivity and shorter block-length codes.

Selected topics in the Hydrodynamics of floating offshore wind turbines: heave damping and second order surge motions

La Energía eléctrica producida mediante tecnología eólica flotante es uno de los recursos más prometedores para reducir la dependencia de energía proveniente de combustibles fósiles. Esta tecnología es de especial interés en países como España, donde la plataforma continental es estrecha y existen pocas áreas para el desarrollo de estructuras fijas. Entre los diferentes conceptos flotantes, esta tesis se ha ocupado de la tipología semisumergible. Estas plataformas pueden experimentar movimientos resonantes en largada y arfada. En largada, dado que el periodo de resonancia es largo estos puede ser inducidos por efectos de segundo orden de deriva lenta que pueden tener una influencia muy significativa en las cargas en los fondeos. En arfada las fuerzas de primer orden pueden inducir grandes movimientos y por tanto la correcta determinación del amortiguamiento es esencial para la analizar la operatividad de la plataforma. Esta tesis ha investigado estos dos efectos, para ello se ha usado como caso base el diseño de una plataforma desarrollada en el proyecto Europeo Hiprwind. La plataforma se compone de 3 columnas cilíndricas unidas mediante montantes estructurales horizontales y diagonales, Los cilindros proporcionan flotabilidad y momentos adrizante. A la base de cada columna se le ha añadido un gran “Heave Plate” o placa de cierre. El diseño es similar a otros diseños previos (Windfloat). Se ha fabricado un modelo a escala de una de las columnas para el estudio detallado del amortiguamiento mediante oscilaciones forzadas. Las dimensiones del modelo (1m diámetro en la placa de cierre) lo hacen, de los conocidos por el candidato, el mayor para el que se han publicado datos. El diseño del cilindro se ha realizado de tal manera que permite la fijación de placas de cierre planas o con refuerzo, ambos modelos se han fabricado y analizado. El modelo con refuerzos es una reproducción exacta del diseño a escala real incluyendo detalles distintivos del mismo, siendo el más importante la placa vertical perimetral. Los ensayos de oscilaciones forzadas se han realizado para un rango de frecuencias, tanto para el disco plano como el reforzado. Se han medido las fuerzas durante los ensayos y se han calculado los coeficientes de amortiguamiento y de masa añadida. Estos coeficientes son necesarios para el cálculo del fondeo mediante simulaciones en el dominio del tiempo. Los coeficientes calculados se han comparado con la literatura existente, con cálculos potenciales y por ultimo con cálculos CFD. Para disponer de información relevante para el diseño estructural de la plataforma se han medido y analizado experimentalmente las presiones en la parte superior e inferior de cada placa de cierre. Para la correcta estimación numérica de las fuerzas de deriva lenta en la plataforma se ha realizado una campaña experimental que incluye ensayos con modelo cautivo de la plataforma completa en olas bicromaticas. Pese a que estos experimentos no reproducen un escenario de oleaje realista, los mismos permiten una verificación del modelo numérico mediante la comparación de fuerzas medidas en el modelo físico y el numérico. Como resultados de esta tesis podemos enumerar las siguientes conclusiones. 1. El amortiguamiento y la masa añadida muestran una pequeña dependencia con la frecuencia pero una gran dependencia con la amplitud del movimiento. siendo coherente con investigaciones existentes. 2. Las medidas con la placa de cierre reforzada con cierre vertical en el borde, muestra un amortiguamiento significativamente menor comparada con la placa plana. Esto implica que para ensayos de canal es necesario incluir estos detalles en el modelo. 3. La masa añadida no muestra grandes variaciones comparando placa plana y placa con refuerzos. 4. Un coeficiente de amortiguamiento del 6% del crítico se puede considerar conservador para el cálculo en el dominio de la frecuencia. Este amortiguamiento es equivalente a un coeficiente de “drag” de 4 en elementos de Morison cuadráticos en las placas de cierre usadas en simulaciones en el dominio del tiempo. 5. Se han encontrado discrepancias en algunos valores de masa añadida y amortiguamiento de la placa plana al comparar con datos publicados. Se han propuesto algunas explicaciones basadas en las diferencias en la relación de espesores, en la distancia a la superficie libre y también relacionadas con efectos de escala. 6. La presión en la placa con refuerzos son similares a las de la placa plana, excepto en la zona del borde donde la placa con refuerzo vertical induce una gran diferencias de presiones entre la cara superior e inferior. 7. La máxima diferencia de presión escala coherentemente con la fuerza equivalente a la aceleración de la masa añadida distribuida sobre la placa. 8. Las masas añadidas calculadas con el código potencial (WADAM) no son suficientemente precisas, Este software no contempla el modelado de placas de pequeño espesor con dipolos, la poca precisión de los resultados aumenta la importancia de este tipo de elementos al realizar simulaciones con códigos potenciales para este tipo de plataformas que incluyen elementos de poco espesor. 9. Respecto al código CFD (Ansys CFX) la precisión de los cálculos es razonable para la placa plana, esta precisión disminuye para la placa con refuerzo vertical en el borde, como era de esperar dado la mayor complejidad del flujo. 10. Respecto al segundo orden, los resultados, en general, muestran que, aunque la tendencia en las fuerzas de segundo orden se captura bien con los códigos numéricos, se observan algunas reducciones en comparación con los datos experimentales. Las diferencias entre simulaciones y datos experimentales son mayores al usar la aproximación de Newman, que usa únicamente resultados de primer orden para el cálculo de las fuerzas de deriva media. 11. Es importante remarcar que las tendencias observadas en los resultados con modelo fijo cambiarn cuando el modelo este libre, el impacto que los errores en las estimaciones de fuerzas segundo orden tienen en el sistema de fondeo dependen de las condiciones ambientales que imponen las cargas ultimas en dichas líneas. En cualquier caso los resultados que se han obtenido en esta investigación confirman que es necesaria y deseable una detallada investigación de los métodos usados en la estimación de las fuerzas no lineales en las turbinas flotantes para que pueda servir de guía en futuros diseños de estos sistemas. Finalmente, el candidato espera que esta investigación pueda beneficiar a la industria eólica offshore en mejorar el diseño hidrodinámico del concepto semisumergible. ABSTRACT Electrical power obtained from floating offshore wind turbines is one of the promising resources which can reduce the fossil fuel energy consumption and cover worldwide energy demands. The concept is the most competitive in countries, such as Spain, where the continental shelf is narrow and does not provide space for fixed structures. Among the different floating structures concepts, this thesis has dealt with the semisubmersible one. Platforms of this kind may experience resonant motions both in surge and heave directions. In surge, since the platform natural period is long, such resonance can be excited with second order slow drift forces and may have substantial influence on mooring loads. In heave, first order forces can induce significant motion, whose damping is a crucial factor for the platform downtime. These two topics have been investigated in this thesis. To this aim, a design developed during HiPRWind EU project, has been selected as reference case study. The platform is composed of three cylindrical legs, linked together by a set of structural braces. The cylinders provide buoyancy and restoring forces and moments. Large circular heave plates have been attached to their bases. The design is similar to other documented in literature (e.g. Windfloat), which implies outcomes could have a general value. A large scale model of one of the legs has been built in order to study heave damping through forced oscillations. The final dimensions of the specimen (one meter diameter discs) make it, to the candidate’s knowledge, the largest for which data has been published. The model design allows for the fitting of either a plain solid heave plate or a flapped reinforced one; both have been built. The latter is a model scale reproduction of the prototype heave plate and includes some distinctive features, the most important being the inclusion of a vertical flap on its perimeter. The forced oscillation tests have been conducted for a range of frequencies and amplitudes, with both the solid plain model and the vertical flap one. Forces have been measured, from which added mass and damping coefficients have been obtained. These are necessary to accurately compute time-domain simulations of mooring design. The coefficients have been compared with literature, and potential flow and CFD predictions. In order to provide information for the structural design of the platform, pressure measurements on the top and bottom side of the heave discs have been recorded and pressure differences analyzed. In addition, in order to conduct a detailed investigation on the numerical estimations of the slow-drift forces of the HiPRWind platform, an experimental campaign involving captive (fixed) model tests of a model of the whole platform in bichromatic waves has been carried out. Although not reproducing the more realistic scenario, these tests allowed a preliminary verification of the numerical model based directly on the forces measured on the structure. The following outcomes can be enumerated: 1. Damping and added mass coefficients show, on one hand, a small dependence with frequency and, on the other hand, a large dependence with the motion amplitude, which is coherent with previously published research. 2. Measurements with the prototype plate, equipped with the vertical flap, show that damping drops significantly when comparing this to the plain one. This implies that, for tank tests of the whole floater and turbine, the prototype plate, equipped with the flap, should be incorporated to the model. 3. Added mass values do not suffer large alterations when comparing the plain plate and the one equipped with a vertical flap. 4. A conservative damping coefficient equal to 6% of the critical damping can be considered adequate for the prototype heave plate for frequency domain analysis. A corresponding drag coefficient equal to 4.0 can be used in time domain simulations to define Morison elements. 5. When comparing to published data, some discrepancies in added mass and damping coefficients for the solid plain plate have been found. Explanations have been suggested, focusing mainly on differences in thickness ratio and distance to the free surface, and eventual scale effects. 6. Pressures on the plate equipped with the vertical flap are similar in magnitude to those of the plain plate, even though substantial differences are present close to the edge, where the flap induces a larger pressure difference in the reinforced case. 7. The maximum pressure difference scales coherently with the force equivalent to the acceleration of the added mass, distributed over the disc surface. 8. Added mass coefficient values predicted with the potential solver (WADAM) are not accurate enough. The used solver does not contemplate modeling thin plates with doublets. The relatively low accuracy of the results highlights the importance of these elements when performing potential flow simulations of offshore platforms which include thin plates. 9. For the full CFD solver (Ansys CFX), the accuracy of the computations is found reasonable for the plain plate. Such accuracy diminishes for the disc equipped with a vertical flap, an expected result considering the greater complexity of the flow. 10. In regards to second order effects, in general, the results showed that, although the main trend in the behavior of the second-order forces is well captured by the numerical predictions, some under prediction of the experimental values is visible. The gap between experimental and numerical results is more pronounced when Newman’s approximation is considered, making use exclusively of the mean drift forces calculated in the first-order solution. 11. It should be observed that the trends observed in the fixed model test may change when the body is free to float, and the impact that eventual errors in the estimation of the second-order forces may have on the mooring system depends on the characteristics of the sea conditions that will ultimately impose the maximum loads on the mooring lines. Nevertheless, the preliminary results obtained in this research do confirm that a more detailed investigation of the methods adopted for the estimation of the nonlinear wave forces on the FOWT would be welcome and may provide some further guidance for the design of such systems. As a final remark, the candidate hopes this research can benefit the offshore wind industry in improving the hydrodynamic design of the semi-submersible concept.

Contribución al conocimiento de los primeros geotécnicos del siglo XX

Leyendo distintos artículos en la Revista de Obras Públicas (Jiménez Salas, 1945) uno recuerda a las grandes figuras como Coulomb (1773), Poncelet (1840), Rankine (1856), Culmann (1866), Mohr (1871), Boussinesq (1876) y otros muchos, que construyeron la base de un conocimiento que poco a poco irían facilitando la complicada tarea que suponía la construcción. Pero sus avances eran aproximaciones que presentaban notables diferencias frente al comportamiento de la naturaleza. Esas discrepancias con la naturaleza llegó un momento que se hicieron demasiado patentes. Importantes asientos en la construcción de los modernos edificios, rotura de presas de materiales sueltos y grandes corrimientos de tierras, por ejemplo durante la construcción del canal de Panamá, llevaron a la Sociedad Americana de Ingenieros Civiles (ASCE) a crear un comité que analizase las prácticas de la construcción de la época. Hechos similares se producían en Europa, por ejemplo en desmontes para ferrocarriles, que en el caso de Suecia supusieron unas cuantiosas perdidas materiales y humanas. El ingeniero austriaco-americano Karl Terzaghi (1883) había podido comprobar, en su práctica profesional, la carencia de conocimientos para afrontar muchos de los retos que la naturaleza ofrecía. Inicialmente buscó la respuesta en la geología pero encontró que ésta carecía de la definición necesaria para la práctica de la ingeniería, por lo que se lanzó a una denodada tarea investigadora basada en el método experimental. Comenzó en 1917 con escasos medios, pero pronto llegó a desarrollar algunos ensayos que le permitieron establecer los primeros conceptos de una nueva ciencia, la Mecánica de Suelos. Ciencia que ve la luz en 1925 con la publicación de su libro Erdbaumechanik auf bodenphysikalischer Grundlage. Rápidamente otras figuras empezaron a hacer sus contribuciones científicas y de divulgación, como es el caso del ingeniero austriaco-americano Arthur Casagrande (1902), cuya iniciativa de organizar el primer Congreso Internacional de Mecánica de Suelos e Ingeniería de Cimentaciones proporcionó el altavoz que necesitaba esa nueva ciencia para su difusión. Al mismo tiempo, más figuras internacionales se fueron uniendo a este período de grandes avances e innovadores puntos de vista. Figuras como Alec Skempton (1914) en el Reino Unido, Ralph Peck (1912) en los Estados Unidos o Laurits Bjerrum (1918) en Noruega sobresalieron entre los grandes de la época. Esta tesis investiga las vidas de estos geotécnicos, artífices de múltiples avances científicos de la nueva ciencia denominada Mecánica de Suelos. Todas estas grandes figuras de la geotecnia fueron presidentes, en distintos periodos, de la Sociedad Internacional de Mecánica de Suelos e Ingeniería de Cimentaciones. Se deja constancia de ello en las biografías que han sido elaboradas a partir de fuentes de variada procedencia y de los datos cruzados encontrados sobre estos extraordinarios geotécnicos. Así, las biografías de Terzaghi, Casagrande, Skempton, Peck y Bjerrum contribuyen no solo a su conocimiento individual sino que constituyen conjuntamente un punto de vista privilegiado para la comprensión de los acontecimientos vividos por la Mecánica de Suelos en el segundo tercio del siglo XX, extendiéndose en algunos casos hasta los albores del siglo XXI. Las aportaciones científicas de estos geotécnicos encuentran también su lugar en la parte técnica de esta tesis, en la que sus contribuciones individuales iniciales que configuran los distintos capítulos conservan sus puntos de vista originales, lo que permite tener una visión de los principios de la Mecánica de Suelos desde su mismo origen. On reading several articles in the journal, Revista de Obras Públicas (Jiménez Salas, 1945), one recalls such leading figures as Coulomb (1773), Poncelet (1840), Rankine (1856), Culmann (1866), Mohr (1871) and Boussinesq (1876) among many others, who created the basis of scientific knowledge that would make the complicated task of construction progressively easier. However, their advances were approximations which suffered considerable discrepancies when faced with the behaviour of the forces of nature. There came a time when such discrepancies became all too evident. Substantial soil settlements when constructing modern buildings, embankment dam failures and grave landslides, during the construction of the Panama Canal for example, led the American Society of Civil Engineers (ASCE) to form a committee in order to analyse construction practices of the time. Similar incidents had taken place in Europe, for example with railway slides, which in the case of Sweden, had resulted in heavy losses in both materials and human lives. During the practice of his career, the Austrian-American engineer Karl Terzaghi (1883) had encountered the many challenges posed by the forces of nature and the lack of knowledge at his disposal with which to overcome them. Terzaghi first sought a solution in geology only to discover that this lacked the necessary accuracy for the practice of engineering. He therefore threw himself into tireless research based on the experimental method. He began in 1917 on limited means but soon managed to develop several tests, which would allow him to establish the basic fundamentals of a new science; Soil Mechanics, a science which first saw the light of day on the publication of Terzaghi’s book, Erdbaumechanik auf bodenphysikalischer Grundlage. Other figures were quick to make their own scientific contributions. Such was the case of Austrian-American engineer, Arthur Casagrande (1902), whose initiative to organize the first International Congress of Soil Mechanics and Foundation Engineering provided the springboard that this science needed. At the same time, other international figures were becoming involved in this period of great advances and innovative concepts. Figures including the likes of Alec Skempton (1914) in the United Kingdom, Ralph Peck (1912) in the United States, and Laurits Bjerrum (1918) in Norway stood out amongst the greatest of their time. This thesis investigates the lives of these geotechnical engineers to whom we are indebted for a great many scientific advances in this new science known as Soil Mechanics. Moreover, each of these eminent figures held the presidency of the International Society of Soil Mechanics and Foundation Engineering, record of which can be found in their biographies, drawn from diverse sources, and by crosschecking and referencing all the available information on these extraordinary geotechnical engineers. Thus, the biographies of Terzaghi, Casagrande, Skempton, Peck and Bjerrum not only serve to provide knowledge on the individual, but moreover, as a collective, they present us with an exceptional insight into the important developments which took place in Soil Mechanics in the second third of the 20th century, and indeed, in some cases, up to the dawn of the 21st. The scientific contributions of these geotechnical engineers also find their place in the technical part of this thesis in which the initial individual contributions which make up several chapters retain their original approaches allowing us a view of the principles of Soil Mechanics from its very beginnings.

Optimización de cimentaciones directas de medianería y esquina mediante modelos de elementos finitos

Existe un amplio catálogo de posibles soluciones para resolver la problemática de las zapatas de medianería así como, por extensión, las zapatas de esquina como caso particular de las anteriores. De ellas, las más habitualmente empleadas en estructuras de edificación son, por un lado, la utilización de una viga centradora que conecta la zapata de medianería con la zapata del pilar interior más próximo y, por otro, la colaboración de la viga de la primera planta trabajando como tirante. En la primera solución planteada, el equilibrio de la zapata de medianería y el centrado de la respuesta del terreno se consigue gracias a la colaboración del pilar interior con su cimentación y al trabajo a flexión de la viga centradora. La modelización clásica considera que se logra un centrado total de la reacción del terreno, con distribución uniforme de las tensiones de contacto bajo ambas zapatas. Este planteamiento presupone, por tanto, que la viga centradora logra evitar cualquier giro de la zapata de medianería y que el pilar puede, por ello, considerarse perfectamente empotrado en la cimentación. En este primer modelo, el protagonismo fundamental recae en la viga centradora, cuyo trabajo a flexión conduce frecuentemente a unas escuadrías y a unas cuantías de armado considerables. La segunda solución, plantea la colaboración de la viga de la primera planta, trabajando como tirante. De nuevo, los métodos convencionales suponen un éxito total en el mecanismo estabilizador del tirante, que logra evitar cualquier giro de la zapata de medianería, dando lugar a una distribución de tensiones también uniforme. Los modelos convencionales existentes para el cálculo de este tipo de cimentaciones presentan, por tanto, una serie de simplificaciones que permiten el cálculo de las mismas, por medios manuales, en un tiempo razonable, pero presentan el inconveniente de su posible alejamiento del comportamiento real de la cimentación, con las consecuencias negativas que ello puede suponer en el dimensionamiento de estos elementos estructurales. La presente tesis doctoral desarrolla un contraste de los modelos convencionales de cálculo de cimentaciones de medianería y esquina, mediante un análisis alternativo con modelos de elementos finitos, con el objetivo de poner de manifiesto las diferencias entre los resultados obtenidos con ambos tipos de modelización, analizar cuáles son las variables que más influyen en el comportamiento real de este tipo de cimentaciones y proponer un nuevo modelo de cálculo, de tipo convencional, más ajustado a la realidad. El proceso de investigación se desarrolla mediante una etapa experimental virtual que utiliza como modelo un pórtico tipo de edificación, ortogonal, de hormigón armado, con dos vanos y número variable de plantas. Tras identificar el posible giro de la cimentación como elemento clave en el comportamiento de las zapatas de medianería y de esquina, se adoptan como variables de estudio aquellas que mayor influencia puedan tener sobre el citado giro de las zapatas y sobre la rigidez del conjunto del elemento estructural. Así, se han estudiado luces de 3 m a 7 m, diferente número de plantas desde baja+1 hasta baja+4, resistencias del terreno desde 100 kN/m2 hasta 300 kN/m2, relaciones de forma de la zapata de medianería de 1,5 : 1 y 2 : 1, aumento y reducción de la cuantía de armado de la viga centradora y variación del canto de la viga centradora desde el mínimo canto compatible con el anclaje de la armadura de los pilares hasta un incremento del 75% respecto del citado canto mínimo. El conjunto de pórticos generados al aplicar las variables indicadas, se ha calculado tanto por métodos convencionales como por el método de los elementos finitos. Los resultados obtenidos ponen de manifiesto importantes discrepancias entre ambos métodos que conducen a importantes diferencias en el dimensionamiento de este tipo de cimentaciones. El empleo de los métodos tradicionales da lugar, por un lado, a un sobredimensionamiento de la armadura de la viga centradora y, por otro, a un infradimensionamiento, tanto del canto de la viga centradora, como del tamaño de la zapata de medianería y del armado de la viga de la primera planta. Finalizado el análisis y discusión de resultados, la tesis propone un nuevo método alternativo, de carácter convencional y, por tanto, aplicable a un cálculo manual en un tiempo razonable, que permite obtener los parámetros clave que regulan el comportamiento de las zapatas de medianería y esquina, conduciendo a un dimensionamiento más ajustado a las necesidades reales de este tipo de cimentación. There is a wide catalogue of possible solutions to solve the problem of party shoes and, by extension, corner shoes as a special case of the above. From all of them, the most commonly used in building structures are, on one hand, the use of a centering beam that connects the party shoe with the shoe of the nearest interior pillar and, on the other hand, the collaboration of the beam of the first floor working as a tie rod. In the first proposed solution, the balance of the party shoe and the centering of the ground response is achieved thanks to the collaboration of the interior pillar with his foundation along with the bending work of the centering beam. Classical modeling considers that a whole centering of the ground reaction is achieved, with uniform contact stress distribution under both shoes. This approach to the issue presupposes that the centering beam manages to avoid any rotation of the party shoe, so the pillar can be considered perfectly embedded in the foundation. In this first model, the leading role lies in the centering beam, whose bending work usually leads to important section sizes and high amounts of reinforced. The second solution, consideres the collaboration of the beam of the first floor, working as tie rod. Again, conventional methods involve a total success in the stabilizing mechanism of the tie rod, that manages to avoid any rotation of the party shoe, resulting in a stress distribution also uniform. Existing conventional models for calculating such foundations show, therefore, a series of simplifications which allow calculation of the same, by manual means, in a reasonable time, but have the disadvantage of the possible distance from the real behavior of the foundation, with the negative consequences this could bring in the dimensioning of these structural elements. The present thesis develops a contrast of conventional models of calculation of party and corner foundations by an alternative analysis with finite element models with the aim of bring to light the differences between the results obtained with both types of modeling, analysis which are the variables that influence the real behavior of this type of foundations and propose a new calculation model, conventional type, more adjusted to reality. The research process is developed through a virtual experimental stage using as a model a typical building frame, orthogonal, made of reinforced concrete, with two openings and variable number of floors. After identifying the possible spin of the foundation as the key element in the behavior of the party and corner shoes, it has been adopted as study variables, those that may have greater influence on the spin of the shoes and on the rigidity of the whole structural element. So, it have been studied lights from 3 m to 7 m, different number of floors from lower floor + 1 to lower floor + 4, máximum ground stresses from 100 kN/m2 300 kN/m2, shape relationships of party shoe 1,5:1 and 2:1, increase and decrease of the amount of reinforced of the centering beam and variation of the height of the centering beam from the minimum compatible with the anchoring of the reinforcement of pillars to an increase of 75% from the minimum quoted height. The set of frames generated by applying the indicated variables, is calculated both by conventional methods such as by the finite element method. The results show significant discrepancies between the two methods that lead to significant differences in the dimensioning of this type of foundation. The use of traditional methods results, on one hand, to an overdimensioning of the reinforced of the centering beam and, on the other hand, to an underdimensioning, both the height of the centering beam, such as the size of the party shoe and the reinforced of the beam of the first floor. After the analysis and discussion of results, the thesis proposes a new alternative method, conventional type and, therefore, applicable to a manual calculation in a reasonable time, that allows to obtain the key parameters that govern the behavior of party and corner shoes, leading to a dimensioning more adjusted to the real needings of this type of foundation.

Vivienda y fondo edificatorio: análisis de las consecuencias del parámetro fondo en el edificio de vivienda colectiva

Este estudio ofrece una herramienta de aproximación al espacio morfológico-métrico en el que se formula la ciudad de alta densidad desde la vivienda colectiva. La vivienda colectiva es la célula básica de la ciudad. El estudio configurativo y dimensional del tejido urbano muestra la importancia del fondo edificatorio como parámetro clave a mitad de camino entre la vivienda y la ciudad. El fondo edificatorio traza el margen de la arquitectura en la ciudad y desde él se equipa y cuantifica el territorio urbano. Sus dinámicas van caracterizando los distintos entornos, mientras en su interior se formula el tipo en un ajuste de continua verificación y adaptación. La forma de la ciudad y sus distintas posibilidades configurativas —en cuanto masa construida y espacio público, pero sin perder de vista la relación entre ambos— depende en gran medida del fondo edificatorio. Se trata, por tanto, de un parámetro importante de relación entre las distintas configuraciones del espacio exterior e interior. Al proyectar, una vez establecido un fondo, algunas propiedades se adaptan con facilidad mientras que otras requieren un cierto grado de interpretación o deben ser descartadas. Dada una superficie, la especificación del fondo fuerza la dimensión del frente en las configuraciones posibles. Ambas dimensiones son vitales en el valor del factor de forma del continuo edificado y en su relación se produce el complejo rango de posibilidades. Partiendo de la ciudad, un gran fondo encierra y mezcla en su interior todo tipo de usos sin distinción, repercute un menor coste por unidad de superficie edificada y comparte su frente reduciendo los intercambios térmicos y lumínicos. Sin embargo la ciudad de fondo reducido ajusta la forma al uso y se desarrolla linealmente con repetitividad a lo largo de sus frentes exteriores. En ella, el fuerte intercambio energético se opone a las grandes posibilidades del espacio libre. En cambio desde la casa las distintas medidas del fondo se producen bajo determinados condicionantes: clima, compacidad, ocupación, hibridación, tamaño de casa, etc., mientras que el tipo se desarrolla en base a una métrica afín. Este trabajo parte de esta dialéctica. Estudia la relación de dependencia entre las condiciones del edificio de viviendas y su métrica. Jerarquiza edificios en base al parámetro “fondo” para constituir una herramienta que como un ábaco sea capaz de visibilizar las dinámicas relacionales entre configuración y métrica bajo la condición de alta densidad. Para ello en una primera fase se gestiona una extensa muestra de edificios representativos de vivienda colectiva principalmente europea, extraída de tres prestigiosos libros en forma de repertorio. Se ordenan y categorizan extrayendo datos conmensurables y temas principales que ligan la profundidad de la huella a la morfología y posteriormente, esta información se estudia en diagramas que ponen de manifiesto convergencias y divergencias, acumulaciones y vacíos, límites, intervalos característicos, márgenes y ejes, parámetros y atributos... cuya relación trata de factorizar el lugar morfológico y métrico de la casa como metavivienda y ciudad. La herramienta se establece así como un complejo marco relacional en el que posicionar casos concretos y trazar nexos transversales, tanto de tipo morfológico como cultural, climático o técnico, normativo o tecnológico. Cada nuevo caso o traza añadida produce consonancias y disonancias en el marco que requieren interpretación y verificación. De este modo este instrumento de análisis comparativo se tempera, se especializa, se completa y se perfecciona con su uso. La forma de la residencia en la ciudad densa se muestra así sobre un subsistema morfológico unitario y su entendimiento se hace más fácilmente alcanzable y acumulable tanto para investigaciones posteriores como para el aprendizaje o el ejercicio profesional. ABSTRACT This research study offers a tool to approach the morphometric space in which (multi-family) housing defines high-density cities. Multi-family housing is the basic cell of the city. The configuration and dimension studies of the urban fabric render the importance of building depth as a key parameter half way between the dwelling and the city. The building depth traces de limit of architecture in the city. It qualifies and quantifies the urban territory. Its dynamics characterize the different environments while in its essence, an adjustment process of continuous verification and adaption defines type. The shape of the city and its different configuration possibilities —in terms of built fabric and public space, always keeping an eye on the relationship between them— depend majorly on the building depth. Therefore, it is a relevant parameter that relates the diverse configurations between interior and exterior space. When designing, once the depth is established, some properties are easily adpated. However, others require a certain degree of interpretation or have to be left out of the study. Given a ceratin surface, the establishment of the depth forces the dimensions of the facade in the different configurations. Both depth and facade dimensions are crucial for the form factor of the built mass. Its relationship produces a complex range of possibilities. From an urban point of view, great depth means multiple uses (making no distinction whatsoever,) it presents a lower cost per unit of built area and shares its facade optimizing temperature and light exchange. On the contrary, the city of reduced depth adjusts its shape to the use, and develops linearly and repetitively along its facades. The strong energy exchange opposes to the great possibilities of free space. From the perspective of the dwelling, the different dimensions of depth are produced under certain determinants: climate, compactness, occupancy, hybridization, dwelling size, etc. Meanwhile, the type is developed based on a related meter (as in poetry). This work starts from the previous premise. It studies the dependency relation bewteen the conditions of the dwellings and their meter (dimensions). It organizes buildings hierarchically based on the parameter “depth” to create a tool that, as an abacus, is able to visibilise the relational dynamics between configuration and dimension in high density conditions. For this, in the first stage a large group of representative multi-family housing buildings is managed, mostly from Europe, picked from three prestigious books as a repertoir. They are categorized and ordered drawing commensurable data and key issues that link the depth of the fooprint to its morphology. Later, this information is studied deeply with diagrams that bring out connections and discrepancies, voids and accumulations, limits, charasteristic intervals, margins and axii, parameters, attributes, etc. These relationships try to create factors from a morphological and metrical point of view of the house as a metadwelling. This tool is established as a complex relation frame in which case studies are postitioned and cross-cutting nexii are traced. These can deal with morphology, climate, technique, law or technology. Each new case or nexus produces affinities and discrepancies that require interpretation and verification. Thus, this instrument of comparative analysis is fine-tuned, especialized and completed as its use is improved. The way housing is understood in high density cities is shown as a unitary metric subsystem and its understanding is easy to reach and accumulate for future researchers, students or practicing architects.

Formación y determinación del valor del suelo: confrontación y discrepancias entre mecanismos de mercado y regulaciones administrativas

La determinación del valor del suelo implicado en los procesos de urbanización se mueve en una compleja dialéctica en la que algunos fenómenos de naturaleza morfológica como el modelado del espacio social, o el que se deduce de las determinaciones del planeamiento (aprovechamiento especialmente) se enfrentan a instrumentos de regulación que se rigen por normas de carácter administrativo (urbanísticas y expropiatorias, fiscales, financieras-hipotecarias etc.). En ese marco en el que las discrepancias son frecuentes se pretende analizar las posibles actuaciones encaminadas a influir sobre la formación de ese valor en el sentido de limitar las expectativas de aprovechamiento tradicionalmente vinculadas al sistema urbanístico establecido, destacando al respecto la implantación de criterios de sostenibilidad y participación ciudadana, así como que la utilización de normas administrativas de valoración con la finalidad de reducir tales expectativas y tratar de influir sobre el sistema urbanístico en su conjunto, no se considera suficiente para conseguir el logro de tales objetivos. Añadiendo, respecto del conjunto de normas administrativas de determinación del valor del suelo, que si bien las reglas urbanísticas y expropiatorias establecen actualmente reglas objetivas de valoración, a través de la normativa de valoración destinada a entidades financieras, o de carácter fiscal, se introducen criterios subjetivos que tratan de aproximarse al mercado, incluso en el caso del valor catastral, estructuralmente reglado. Esta separación de criterios ha llevado a un enfrentamiento al que ha venido a dar respuesta la reciente sentencia del Tribunal Supremo de 30 de mayo de 2014, que impone los criterios urbanísticos de consideración de situaciones básicas de suelo, frente a los fiscalmente regulados en relación con la normativa catastral en cuanto a la consideración de suelo urbanizable sin desarrollar, que pasa a ser considerado como en situación rural, siendo por tanto aplicables sobre el mismo las reglas de valoración que la normativa catastral establece para esta categoría de suelo (rústico) que no considera, incluso con la posterior modificación, de junio de 2015, incorporada para adaptarse a la mencionada sentencia, expectativas de aprovechamiento. Pero como se ha señalado, la exclusiva utilización de la normativa urbanística de valoración no se considera suficiente para evitar los efectos que sobre el valor de suelo produce la asignación de tales aprovechamientos, por lo que acuerdo con la actual legislación de suelo, deben asimismo potenciarse actuaciones encaminadas a un desarrollo sostenible así como a la participación ciudadana, la transparencia y el control, con la finalidad de lograr un mayor rigor en la utilización del suelo que ha de traducirse en su valoración. ABSTRACT Determining the land value involved in the urbanisation process implies a complex dialectic in which certain morphological natural phenomena like the modelling of social space or that deduced from planning determinations (especially land use) face regulatory instruments governed by administrative norms (urban planning and expropriator, tax, financial-mortgage etc.). In this context where discrepancies are common, the purpose is to analyse the possible actions geared to influence the formation of that value in the sense of limiting land use expectations traditionally linked to the established urban planning system, highlighting the implementation of sustainability criteria and citizen participation, as well as to consider that the administrative standards of evaluation for reducing said expectations, and trying to influence the urban system as a whole, are not considered sufficient for achieving these objectives. We might add, with respect to the set of administrative norms for determining the land value, that while urban and expropriations norms currently provide objective rules of valuation, subjective criteria are introduced trying to approach the market, including the structurally regulated cadastral value through valuation rules aimed at financial or fiscal institutions. This separation of criteria has led to a confrontation to which the recent ruling of the Supreme Court of May 30, 2014 responds. The aforementioned judgement imposes the urban core criteria for basic land use situations against those fiscally regulated in relation to cadastral regulations regarding the consideration of undeveloped building land, which is considered to be in a rural situation, making it subject to the same rules that cadastral valuation norms established for this category of land use (rustic) which do not consider, even with the subsequent amendment of June 2015, introduced to fit that judgment, use expectations. But as noted, the exclusive use of valuation planning regulations is not considered sufficient to avoid the effects on the land value produced by the allocation of said uses, so that according to the current land use legislation, actions aimed at sustainable development as well as citizen participation, transparency and control, shall be enhanced in order to achieve greater rigor in the use of land which should be translated in their valuation.