Advanced control for floating offshore wind turbines.

El contenido de los capítulos 3, 4 y 5 está sujeto a confidencialidad. 117 p.Los aerogeneradores flotantes presentan diversos retos tecnológicos, entre los cuales, las atenuaciones de la dinámica producida por el empuje del viento y la inducida por el oleaje, debido a la baja rigidez hidrodinámica de la plataforma, son vitales. Estas dinámicas no solo influyen en el funcionamiento normal del aerogenerador, sino que además, incrementan las cargas mecánicas de algunos componentes, como la torre y palas del aerogenerador. Por ello, el objetivo de esta tesis es minimizar las dinámicas de los aerogeneradores flotantes, mejorando el funcionamiento a la vez que se reducen las cargas mecánicas producidas en la torre y palas mediante técnicas de control avanzadas, y así, aumentar la eficiencia del aerogenerador y prolongar la vida útil de dichos componentes.La descripción del trabajo incluye el modelado de plataformas flotantes y el desarrollo de dos lazos de control, que respectivamente realimentan la velocidad de la góndola y los momentos flectores en las raíces de las palas, para la contribución en la regulación del ángulo de pitch de las palas del aerogenerador. Además, se estudia la relación de las dimensiones de las plataformas flotantes y el desempeño del controlador diseñado con el fin de reducir las dimensiones de la plataforma manteniendo las propiedades del funcionamiento del aerogenerador. Se proponen dos métodos innovadores para la linealización de los modelos no lineales de aerogeneradores flotantes y la optimización de los lazos de control diseñados en esta tesis. Los resultados mostrados demuestran la eficacia del controlador diseñado en la consecución de los objetivos propuestos

Advanced control for floating offshore wind turbines.

El contenido de los capítulos 3, 4 y 5 está sujeto a confidencialidad. 117 p.os aerogeneradores flotantes presentan diversos retos tecnológicos, entre los cuales, las atenuaciones de la dinámica producida por el empuje del viento y la inducida por el oleaje, debido a la baja rigidez hidrodinámica de la plataforma, son vitales. Estas dinámicas no solo influyen en el funcionamiento normal del aerogenerador, sino que además, incrementan las cargas mecánicas de algunos componentes, como la torre y palas del aerogenerador. Por ello, el objetivo de esta tesis es minimizar las dinámicas de los aerogeneradores flotantes, mejorando el funcionamiento a la vez que se reducen las cargas mecánicas producidas en la torre y palas mediante técnicas de control avanzadas, y así, aumentar la eficiencia del aerogenerador y prolongar la vida útil de dichos componentes.La descripción del trabajo incluye el modelado de plataformas flotantes y el desarrollo de dos lazos de control, que respectivamente realimentan la velocidad de la góndola y los momentos flectores en las raíces de las palas, para la contribución en la regulación del ángulo de pitch de las palas del aerogenerador. Además, se estudia la relación de las dimensiones de las plataformas flotantes y el desempeño del controlador diseñado con el fin de reducir las dimensiones de la plataforma manteniendo las propiedades del funcionamiento del aerogenerador. Se proponen dos métodos innovadores para la linealización de los modelos no lineales de aerogeneradores flotantes y la optimización de los lazos de control diseñados en esta tesis. Los resultados mostrados demuestran la eficacia del controlador diseñado en la consecución de los objetivos propuestos

Model reduction techniques for the fast inversion of Borehole resistivity Measurements

302 p.Las medidas de resistividad en perforaciones a traves de tubos se utilizan de manera común para obteneruna mejor caracterización del subsuelo de la tierra. El uso de un tubo que cubre el pozo complicaenormemente las simulaciones numéricas debido a su finura y al gran contraste entre la conductividad deltubo y la de las formaciones rocosas. En este trabajo, modelizamos el tubo como una membranacilíndrica fina de grosor uniforme. Basándonos en configuraciones realistas, consideramos que laconductividad del tubo es proporcional a su grosor a la potencia de menos tres. En esta tesis doctoral, nosconcentramos en el problema anterior para obtener condiciones de transmisión de impedancia (ITCs) quesirvan para reemplazar el tubo metálico. Para ello, empezamos por considerar un modelo 2D encoordenadas cartesianas, que sirve como una primera aproximación para resolver el problema 3Dcon simetría axial (empleando coordenadas cilíndricas) considerado en la mayoría de las simulacionesrealistas de perforaciones con tubos. Empezamos por considerar el caso estático (frecuencia nula), y mástarde obtenemos ITCs para frecuencias no nulas, las cuales son importantes para entender ciertosfenómenos físicos que ocurren al obtener medidas de resistividad en pozos a través de tubos, como porejemplo, los efectos de Delaware y Groningen. Después, analizamos estos modelos demostrandoresultados de estabilidad y convergencia, y evaluamos el rendimiento numérico de estos modelosempleando el método de elementos finitos. Por último, obetnemos soluciones semi-analíticas para dichosmodelos, las cuales proporcionan una manera más eficiente de evaluar las soluciones a nuestros modelosaproximados en comparación con soluciones puramente numéricas

Correction system for polyphonic piano recordings

M.I. Martin-Erdozain, I. Barbancho, A. Rosa-Pujazon, A.M. Barbancho, "Correction system for polyphonic piano recordings", XXVIII Simposium Nacional de la Unión Científica Internacional de Radio, Santiago de Compostela, España, 2013n this paper, a support tool for piano rehearsal is presented. The system analyses a given piano polyphonic recording to find the times, pitch and duration of the notes and figures played, taking into account the possibility of playing more than one note simultaneously as well as covering the whole piano frequency range. In order to do so, the system uses an onset detection algorithm to segment the input signal into partitions which are then analysed in the time and frequency domains. Then, the system correlates the data extracted from the partitions with the score of the original piece, identifying the positions and type of the mistakes performed by the user, and providing her/him with the corresponding feedback. The experiments conducted showed that the application is capable of analysing a given recording and indicate the musician the mistakes made.This work has been funded by the Ministerio de Economia y Competitividad of the Spanish Government under Project No. TIN2010-21089-C03-02 and by the Ministerio de Industria, Turismo y Comercio under Project No. TSI-090100-2011-25

Fast simulation of through-casing resistivity measurements using semi-analytical asymptotic models. Part 1: Accuracy study

When trying to obtain a better characterization of the Earth's subsurface, it is common to use borehole through-casing resistivity measurements. It is also common for the wells to be surrounded by a metal casing to protect the well and avoid possible collapses. The presence of this metal case highly complicates the numeric simulation of the problem due to the high conductivity of the casing compared to the conductivity of the rock formations. Here we present an application of some theoretical asymptotic methods in order to deal with complex borehole scenarios like cased wells. The main idea consist in replacing the part of the domain related to the casing by a transmission impedance boundary condition. The small thickness of the casing makes it ideal to apply this kind of mathematical technique. When eliminating the casing from the computational domain, the computational cost of the problems considerably decreases, while the effect of the casing does not disappear due to the impedance transmission conditions. The results show that when applying an order three impedance boundary condition for a simplified domain, it only generates a negligible approximation error, while it considerably reduces the computational cost

Asymptotic Models for the Electric Potential across a Highly Conductive Casing

We analyze a configuration that involves a steel-cased borehole, where the casing that covers the borehole is considered as a highly conductive thin layer. We develop an asymptotic method for deriving reduced problems capable of efficiently dealing with the numerical difficulties caused by the casing when applying traditional numerical methods. We derive several reduced models by employing two different approaches, each of them leading to different classes of models. We prove stability and convergence results for these models. The theoretical orders of convergence are supported by numerical results obtained with the finite element method

Using Multiple Fidelity Numerical Models for Floating Offshore Wind Turbine Advanced Control Design

This paper summarises the tuning process of the Aerodynamic Platform Stabiliser control loop and its performance with Floating Offshore Wind Turbine model. Simplified Low-Order Wind turbine numerical models have been used for the system identification and control tuning process. Denmark Technical University's 10 MW wind turbine model mounted on the TripleSpar platform concept was used for this study. Time-domain simulations were carried out in a fully coupled non-linear aero-hydro-elastic simulation tool FAST, in which wind and wave disturbances were modelled. This testing yielded significant improvements in the overall Floating Offshore Wind Turbine performance and load reduction, validating the control technique presented in this work.This work was partially funded by the Spanish Ministry of Economy and Competitiveness through the research project DPI2017-82930-C2-2-R

El igualitarismo de la suerte, Kant y la injusticia de tolerar la pobreza en el mundo

Este artículo pretende ofrecer una defensa plausible y renovada de los principios morales de la ya familiar corriente de filosofía política 'igualitarismo de la suerte', la cual, amparándose no solo en el programa moral kantiano sino también en una serie de intuiciones notablemente arraigadas en nuestros días, goza de una justificación suficientemente sólida como para constituirse en referente ético global, a partir del cual la erradicación de la pobreza sea considerada como un deber moral positivo y, en contraposición, su tolerancia como una clara injusticia. Las tesis presentadas parten de la idea ampliamente aceptada en filosofía moral de que "todas las personas somos iguales en valor moral fundamental", argumentándose que los principios que rigen la doctrina del igualitarismo de la suerte satisfacen dicha máxima hasta sus últimas consecuencias y conforman una teoría sostenible de justicia que es capaz de superar de forma razonable las críticas más importantes que han mermado su mérito en tiempos recientes

Audits and inspections are never enough: a critique to enhance food safety

Internal and external food safety audits are conducted to assess the safety and quality of food including on-farm production, manufacturing practices, sanitation, and hygiene. Some auditors are direct stakeholders that are employed by food establishments to conduct internal audits, while other auditors may represent the interests of a second party purchaser or a third-party auditing agency. Some buyers conduct their own audits or additional testing, while some buyers trust the results of third-party audits or inspections. Third-party auditors, however, use various food safety audit standards and most do not have a vested interest in the products being sold. Audits are conducted under a proprietary standard, while food safety inspections are generally conducted within a legal framework. There have been many foodborne illness outbreaks linked to food processors that have passed third-party audits and inspections, raising questions about the utility of both. Supporters argue third-party audits are a way to ensure food safety in an era of dwindling economic resources. Critics contend that while external audits and inspections can be a valuable tool to help ensure safe food, such activities represent only a snapshot in time. This paper identifies limitations of food safety inspections and audits and provides recommendations for strengthening the system, based on developing a strong food safety culture, including risk-based verification steps, throughout the food safety system

GLOBAL POVERTY AND FOREIGN AID

Sebbene sia comunemente riconosciuto che la povert\ue0 non rappresenti una condizione auspicabile in nessuna societ\ue0, alla luce della grande quantit\ue0 di dati e studi in materia, diventa difficile difendere la persistenza della stessa a causa dell'impossibilit\ue0 di trovare un efficace metodo per sradicarla. Le prove presentate per sostenere l'idea che la povert\ue0 globale sia prevenibile, sono l\u2019essenza delle forze motivazionali che guidano l'elaborazione di questa tesi. Esse sono, in ultima analisi, innescate da un genuino interesse per la comprensione dei fattori che, attualmente, costringono circa 1 miliardo di persone a vivere in una condizione di precariet\ue0. Inoltre, tale interesse \ue8 nutrito dal paradosso per il quale nonostante le persone in genere rifiutino e condannino la miseria umana, gli strumenti principali che sono stati messi in atto dalla comunit\ue0 internazionale per sradicare tale fenomeno \u2014basandosi in modo significativo su aiuti pubblici allo sviluppo (APS)\u2014 godano di grande legittimit\ue0 anche se non presentano n\ue9 risultati chiari n\ue9 pure intenzioni di sviluppo. In sede di esame del sistema di cooperazione internazionale, sembra emergere un divario tra la realt\ue0 e la retorica tradizionale sul tema , il quale pu\uf2 generare alcuni dubbi non solo circa l'adeguatezza delle attuali pratiche di lotta alla povert\ue0, ma anche riguardo le normative su cui si basano tali pratiche. Questa tesi di dottorato analizza la povert\ue0 globale \u2014cos\uec come l\u2019APS\u2014 non solo da un punto di vista della pratica politica (attraverso la ricerca quantitativa e qualitativa), ma anche da una prospettiva filosofico-normativa. Dopo un primo capitolo descrittivo riguardante l\u2019APS, i risultati di questa strategia multidisciplinare vengono presentati divisi in tre capitoli corrispondenti ai tre approcci (quantitativi, qualitativi e normativi), ciascuno dei quali \ue9 incluso in un documento accademico. Nel complesso, essi indicano l'idea che oggi - anche se ci sono abbastanza elementi che sembrano innescare chiari e imperativi doveri morali positivi che impongono di combattere la povert\ue0 globale - ci troviamo immersi in un paradigma di sviluppo che \ue8 intensamente rafforzato dai principali attori coinvolti, che dedicano sforzi eccezionali a diffondere ampiamente lodi e complimenti a un sistema di cooperazione internazionale i cui risultati sono fortemente discutibili.Although it seems commonly agreed upon that poverty does not represent a desirable outcome in any society, in light of the large amount of data and studies on the subject, it becomes hard to defend the persistence of poverty as a result of the impossibility of finding the right path to eradicate it. The evidence raised to support the idea that global poverty is preventable is at the core of the motivational forces driving the elaboration of this thesis, which is ultimately triggered by a genuine interest in understanding the underlying factors that allow around 1 billion people to live precariously at the present moment. Moreover, such interest is nourished by the paradox that although people generally reject and condemn human misery, the main instruments that have been put in place by the international community to eradicate it \u2014relying significantly on Official Development Assistance (ODA)\u2014enjoy great legitimacy even though they do not exhibit nor clear results neither pure developmental intentions. A gap between reality and the traditional rhetoric on the topic seems to emerge when scrutinising the international cooperation apparatus; a gap that can provoke some doubts not only about the adequacy of the current practices for fighting poverty but also regarding the normative grounds on which such practices rest. Hence, this doctoral thesis analyses the global poverty issue\u2014 as well as ODA\u2014 not only from a policy practice perspective (through quantitative and qualitative research) but also from a normative philosophical angle. The results of this multidisciplinary strategy are exposed after a first descriptive chapter on ODA, in three chapters corresponding to the three approaches (quantitative, qualitative and normative), each of them reflected in an academic paper. Overall, they point to the idea that today \u2014even though there are enough elements that seem to trigger clear and imperative positive moral duties that dictate to fight global poverty\u2014 we find ourselves immersed in a development paradigm that is intensively reinforced by the main actors involved in it, who devote outstanding efforts to widely spreading praise and compliments to an international cooperation system whose achievements are highly debatable