Contribution to proactivity in mobile context-aware recommender systems

Los sistemas de recomendación son potentes herramientas de filtrado de información que permiten a usuarios solicitar sugerencias sobre ítems que cubran sus necesidades. Tradicionalmente estas recomendaciones han estado basadas en opiniones de los mismos, así como en datos obtenidos de su consumo histórico o comportamiento en el propio sistema. Sin embargo, debido a la gran penetración y uso de los dispositivos móviles en nuestra sociedad, han surgido nuevas oportunidades en el campo de los sistemas de recomendación móviles gracias a la información contextual que se puede obtener sobre la localización o actividad de los usuarios. Debido a este estilo de vida en el que todo tiende a la movilidad y donde los usuarios están plenamente interconectados, la información contextual no sólo es física, sino que también adquiere una dimensión social. Todo esto ha dado lugar a una nueva área de investigación relacionada con los Sistemas de Recomendación Basados en Contexto (CARS) móviles donde se busca incrementar el nivel de personalización de las recomendaciones al usar dicha información. Por otro lado, este nuevo escenario en el que los usuarios llevan en todo momento un terminal móvil consigo abre la puerta a nuevas formas de recomendar. Sustituir el tradicional patrón de uso basado en petición-respuesta para evolucionar hacia un sistema proactivo es ahora posible. Estos sistemas deben identificar el momento más adecuado para generar una recomendación sin una petición explícita del usuario, siendo para ello necesario analizar su contexto. Esta tesis doctoral propone un conjunto de modelos, algoritmos y métodos orientados a incorporar proactividad en CARS móviles, a la vez que se estudia el impacto que este tipo de recomendaciones tienen en la experiencia de usuario con el fin de extraer importantes conclusiones sobre "qué", "cuándo" y "cómo" se debe notificar proactivamente. Con este propósito, se comienza planteando una arquitectura general para construir CARS móviles en escenarios sociales. Adicionalmente, se propone una nueva forma de representar el proceso de recomendación a través de una interfaz REST, lo que permite crear una arquitectura independiente de dispositivo y plataforma. Los detalles de su implementación tras su puesta en marcha en el entorno bancario español permiten asimismo validar el sistema construido. Tras esto se presenta un novedoso modelo para incorporar proactividad en CARS móviles. Éste muestra las ideas principales que permiten analizar una situación para decidir cuándo es apropiada una recomendación proactiva. Para ello se presentan algoritmos que establecen relaciones entre lo propicia que es una situación y cómo esto influye en los elementos a recomendar. Asimismo, para demostrar la viabilidad de este modelo se describe su aplicación a un escenario de recomendación para herramientas de creación de contenidos educativos. Siguiendo el modelo anterior, se presenta el diseño e implementación de nuevos interfaces móviles de usuario para recomendaciones proactivas, así como los resultados de su evaluación entre usuarios, lo que aportó importantes conclusiones para identificar cuáles son los factores más relevantes a considerar en el diseño de sistemas proactivos. A raíz de los resultados anteriores, el último punto de esta tesis presenta una metodología para calcular cuán apropiada es una situación de cara a recomendar de manera proactiva siguiendo el modelo propuesto. Como conclusión, se describe la validación llevada a cabo tras la aplicación de la arquitectura, modelo de recomendación y métodos descritos en este trabajo en una red social de aprendizaje europea. Finalmente, esta tesis discute las conclusiones obtenidas a lo largo de la extensa investigación llevada a cabo, y que ha propiciado la consecución de una buena base teórica y práctica para la creación de sistemas de recomendación móviles proactivos basados en información contextual. ABSTRACT Recommender systems are powerful information filtering tools which offer users personalized suggestions about items whose aim is to satisfy their needs. Traditionally the information used to make recommendations has been based on users’ ratings or data on the item’s consumption history and transactions carried out in the system. However, due to the remarkable growth in mobile devices in our society, new opportunities have arisen to improve these systems by implementing them in ubiquitous environments which provide rich context-awareness information on their location or current activity. Because of this current all-mobile lifestyle, users are socially connected permanently, which allows their context to be enhanced not only with physical information, but also with a social dimension. As a result of these novel contextual data sources, the advent of mobile Context-Aware Recommender Systems (CARS) as a research area has appeared to improve the level of personalization in recommendation. On the other hand, this new scenario in which users have their mobile devices with them all the time offers the possibility of looking into new ways of making recommendations. Evolving the traditional user request-response pattern to a proactive approach is now possible as a result of this rich contextual scenario. Thus, the key idea is that recommendations are made to the user when the current situation is appropriate, attending to the available contextual information without an explicit user request being necessary. This dissertation proposes a set of models, algorithms and methods to incorporate proactivity into mobile CARS, while the impact of proactivity is studied in terms of user experience to extract significant outcomes as to "what", "when" and "how" proactive recommendations have to be notified to users. To this end, the development of this dissertation starts from the proposal of a general architecture for building mobile CARS in scenarios with rich social data along with a new way of managing a recommendation process through a REST interface to make this architecture multi-device and cross-platform compatible. Details as regards its implementation and evaluation in a Spanish banking scenario are provided to validate its usefulness and user acceptance. After that, a novel model is presented for proactivity in mobile CARS which shows the key ideas related to decide when a situation warrants a proactive recommendation by establishing algorithms that represent the relationship between the appropriateness of a situation and the suitability of the candidate items to be recommended. A validation of these ideas in the area of e-learning authoring tools is also presented. Following the previous model, this dissertation presents the design and implementation of new mobile user interfaces for proactive notifications. The results of an evaluation among users testing these novel interfaces is also shown to study the impact of proactivity in the user experience of mobile CARS, while significant factors associated to proactivity are also identified. The last stage of this dissertation merges the previous outcomes to design a new methodology to calculate the appropriateness of a situation so as to incorporate proactivity into mobile CARS. Additionally, this work provides details about its validation in a European e-learning social network in which the whole architecture and proactive recommendation model together with its methods have been implemented. Finally, this dissertation opens up a discussion about the conclusions obtained throughout this research, resulting in useful information from the different design and implementation stages of proactive mobile CARS.

Optimización de la composición del hueco de fachada en materia de eficiencia energética. Propuesta de indicador como herramienta para el análisis integral del elemento acristalado = Energy performance optimization of window systems. Proposal of an indicator as a tool for an integrated analysis of glazing

La hipótesis de esta tesis es: "La optimización de la ventana considerando simultáneamente aspectos energéticos y aspectos relativos a la calidad ambiental interior (confort higrotérmico, lumínico y acústico) es compatible, siempre que se conozcan y consideren las sinergias existentes entre ellos desde las primeras fases de diseño". En la actualidad se desconocen las implicaciones de muchas de las decisiones tomadas en torno a la ventana; para que su eficiencia en relación a todos los aspectos mencionados pueda hacerse efectiva es necesaria una herramienta que aporte más información de la actualmente disponible en el proceso de diseño, permitiendo así la optimización integral, en función de las circunstancias específicas de cada proyecto. En la fase inicial de esta investigación se realiza un primer acercamiento al tema, a través del estado del arte de la ventana; analizando la normativa existente, los componentes, las prestaciones, los elementos experimentales y la investigación. Se observa que, en ocasiones, altos requisitos de eficiencia energética pueden suponer una disminución de las prestaciones del sistema en relación con la calidad ambiental interior, por lo que surge el interés por integrar al análisis energético aspectos relativos a la calidad ambiental interior, como son las prestaciones lumínicas y acústicas y la renovación de aire. En este punto se detecta la necesidad de realizar un estudio integral que incorpore los distintos aspectos y evaluar las sinergias que se dan entre las distintas prestaciones que cumple la ventana. Además, del análisis de las soluciones innovadoras y experimentales se observa la dificultad de determinar en qué medida dichas soluciones son eficientes, ya que son soluciones complejas, no caracterizadas y que no están incorporadas en las metodologías de cálculo o en las bases de datos de los programas de simulación. Por lo tanto, se plantea una segunda necesidad, generar una metodología experimental para llevar a cabo la caracterización y el análisis de la eficiencia de sistemas innovadores. Para abordar esta doble necesidad se plantea la optimización mediante una evaluación del elemento acristalado que integre la eficiencia energética y la calidad ambiental interior, combinando la investigación teórica y la investigación experimental. En el ámbito teórico, se realizan simulaciones, cálculos y recopilación de información de distintas tipologías de hueco, en relación con cada prestación de forma independiente (acústica, iluminación, ventilación). A pesar de haber partido con un enfoque integrador, resulta difícil esa integración detectándose una carencia de herramientas disponible. En el ámbito experimental se desarrolla una metodología para la evaluación del rendimiento y de aspectos ambientales de aplicación a elementos innovadores de difícil valoración mediante la metodología teórica. Esta evaluación consiste en el análisis comparativo experimental entre el elemento innovador y un elemento estándar; para llevar a cabo este análisis se han diseñado dos espacios iguales, que denominamos módulos de experimentación, en los que se han incorporado los dos sistemas; estos espacios se han monitorizado, obteniéndose datos de consumo, temperatura, iluminancia y humedad relativa. Se ha realizado una medición durante un periodo de nueve meses y se han analizado y comparado los resultados, obteniendo así el comportamiento real del sistema. Tras el análisis teórico y el experimental, y como consecuencia de esa necesidad de integrar el conocimiento existente se propone una herramienta de evaluación integral del elemento acristalado. El desarrollo de esta herramienta se realiza en base al procedimiento de diagnóstico de calidad ambiental interior (CAI) de acuerdo con la norma UNE 171330 “Calidad ambiental en interiores”, incorporando el factor de eficiencia energética. De la primera parte del proceso, la parte teórica y el estado del arte, se obtendrán los parámetros que son determinantes y los valores de referencia de dichos parámetros. En base a los parámetros relevantes obtenidos se da forma a la herramienta, que consiste en un indicador de producto para ventanas que integra todos los factores analizados y que se desarrolla según la Norma UNE 21929 “Sostenibilidad en construcción de edificios. Indicadores de sostenibilidad”. ABSTRACT The hypothesis of this thesis is: "The optimization of windows considering energy and indoor environmental quality issues simultaneously (hydrothermal comfort, lighting comfort, and acoustic comfort) is compatible, provided that the synergies between these issues are known and considered from the early stages of design ". The implications of many of the decisions made on this item are currently unclear. So that savings can be made, an effective tool is needed to provide more information during the design process than the currently available, thus enabling optimization of the system according to the specific circumstances of each project. The initial phase deals with the study from an energy efficiency point of view, performing a qualitative and quantitative analysis of commercial, innovative and experimental windows. It is observed that sometimes, high-energy efficiency requirements may mean a reduction in the system's performance in relation to user comfort and health, that's why there is an interest in performing an integrated analysis of indoor environment aspects and energy efficiency. At this point a need for a comprehensive study incorporating the different aspects is detected, to evaluate the synergies that exist between the various benefits that meet the window. Moreover, from the analysis of experimental and innovative windows, a difficulty in establishing to what extent these solutions are efficient is observed; therefore, there is a need to generate a methodology for performing the analysis of the efficiency of the systems. Therefore, a second need arises, to generate an experimental methodology to perform characterization and analysis of the efficiency of innovative systems. To address this dual need, the optimization of windows by an integrated evaluation arises, considering energy efficiency and indoor environmental quality, combining theoretical and experimental research. In the theoretical field, simulations and calculations are performed; also information about the different aspects of indoor environment (acoustics, lighting, ventilation) is gathered independently. Despite having started with an integrative approach, this integration is difficult detecting lack available tools. In the experimental field, a methodology for evaluating energy efficiency and indoor environment quality is developed, to be implemented in innovative elements which are difficult to evaluate using a theoretical methodology This evaluation is an experimental comparative analysis between an innovative element and a standard element. To carry out this analysis, two equal spaces, called experimental cells, have been designed. These cells have been monitored, obtaining consumption, temperature, luminance and relative humidity data. Measurement has been performed during nine months and results have been analyzed and compared, obtaining results of actual system behavior. To advance this optimization, windows have been studied from the point of view of energy performance and performance in relation to user comfort and health: thermal comfort, acoustic comfort, lighting comfort and air quality; proposing the development of a methodology for an integrated analysis including energy efficiency and indoor environment quality. After theoretical and experimental analysis and as a result of the need to integrate existing knowledge, a comprehensive evaluation procedure for windows is proposed. This evaluation procedure is developed according to the UNE 171330 "Indoor Environmental Quality", also incorporating energy efficiency and cost as factors to evaluate. From the first part of the research process, outstanding parameters are chosen and reference values of these parameters are set. Finally, based on the parameters obtained, an indicator is proposed as windows product indicator. The indicator integrates all factors analyzed and is developed according to ISO 21929-1:2011"Sustainability in building construction. Sustainability indicators. Part 1: Framework for the development of indicators and a core set of indicators for buildings".

PPP in light rail transit systems in Spain

Light rail systems have proliferated in Spain in the last decade, following a tendency that is common not only in other European countries but also in other parts of the world. This paper reviews the benefits of light rail systems, both related to environmental issues and mobility issues. It analyses the evolution of light rail projects in Spain and shows that light rail systems in this country have evolved towards an extensive use of public-private partnerships. The analysis of the Spanish projects, however, does not contribute any conclusive evidence about whether public-private partnerships have been more efficient than publicly owned enterprises in building and operating light rail systems.

Characterization of the environmental performance of the insulating materials in the enveloping of the building.

Insulating materials in buildings are one of the main factors that should be taken into account when talking about sustainability since with a correct application it could imply important savings for the citizens. In the course of its life, a building requires a series of supplies to perform the duties it has been built for, generating an impact on the environment. The selection of one material or another will establish partly the global environmental impact of the building. Choosing the right insulating material will determine the building's general degree of sustainability, both in its heating savings (energy consumption) and in the environmental impacts caused by its LCA (greenhouse gas emissions). Therefore, we propose to establish guidelines to characterize the insulating material with a better environmental performance in all the stages of its life cycle, taking into account the construction system, the use of the building and its location.

An open-source simulation tool of grid-connected PV systems.

This paper will present an open-source simulation tool, which is being developed in the frame of an European research project1. The tool, whose final version will be freely available through a website, allows the modelling and the design of different types of grid-connected PV systems, such as large grid-connected plants and building-integrated installations. The tool is based on previous software developed by the IES-UPM2, whose models and energy losses scenarios have been validated in the commissioning of PV projects3 carried out in Spain, Portugal, France and Italy, whose aggregated capacity is nearly 300MW. This link between design and commissioning is one of the key points of tool presented here, which is not usually addressed by present commercial software. The tool provides, among other simulation results, the energy yield, the analysis and breakdown of energy losses, and the estimations of financial returns adapted to the legal and financial frameworks of each European country. Besides, educational facilities will be developed and integrated in the tool, not only devoted to learn how to use this software, but also to train the users on the best design PV systems practices. The tool will also include the recommendation of several PV community experts, which have been invited to identify present necessities in the field of PV systems simulation. For example, the possibility of using meteorological forecasts as input data, or modelling the integration of large energy storage systems, such as vanadium redox or lithium-ion batteries. Finally, it is worth mentioning that during the verification and testing stages of this software development, it will be also open to the suggestions received from the different actors of the PV community, such as promoters, installers, consultants, etc.

A multi-resource load balancing algorithm for cloud cache systems

With the advent of cloud computing model, distributed caches have become the cornerstone for building scalable applications. Popular systems like Facebook [1] or Twitter use Memcached [5], a highly scalable distributed object cache, to speed up applications by avoiding database accesses. Distributed object caches assign objects to cache instances based on a hashing function, and objects are not moved from a cache instance to another unless more instances are added to the cache and objects are redistributed. This may lead to situations where some cache instances are overloaded when some of the objects they store are frequently accessed, while other cache instances are less frequently used. In this paper we propose a multi-resource load balancing algorithm for distributed cache systems. The algorithm aims at balancing both CPU and Memory resources among cache instances by redistributing stored data. Considering the possible conflict of balancing multiple resources at the same time, we give CPU and Memory resources weighted priorities based on the runtime load distributions. A scarcer resource is given a higher weight than a less scarce resource when load balancing. The system imbalance degree is evaluated based on monitoring information, and the utility load of a node, a unit for resource consumption. Besides, since continuous rebalance of the system may affect the QoS of applications utilizing the cache system, our data selection policy ensures that each data migration minimizes the system imbalance degree and hence, the total reconfiguration cost can be minimized. An extensive simulation is conducted to compare our policy with other policies. Our policy shows a significant improvement in time efficiency and decrease in reconfiguration cost.

Side-Channel Attack Protection Techniques in FPGA Systems using Enhanced Dual-Rail Solutions

Esta tesis doctoral se centra principalmente en técnicas de ataque y contramedidas relacionadas con ataques de canal lateral (SCA por sus siglas en inglés), que han sido propuestas dentro del campo de investigación académica desde hace 17 años. Las investigaciones relacionadas han experimentado un notable crecimiento en las últimas décadas, mientras que los diseños enfocados en la protección sólida y eficaz contra dichos ataques aún se mantienen como un tema de investigación abierto, en el que se necesitan iniciativas más confiables para la protección de la información persona de empresa y de datos nacionales. El primer uso documentado de codificación secreta se remonta a alrededor de 1700 B.C., cuando los jeroglíficos del antiguo Egipto eran descritos en las inscripciones. La seguridad de la información siempre ha supuesto un factor clave en la transmisión de datos relacionados con inteligencia diplomática o militar. Debido a la evolución rápida de las técnicas modernas de comunicación, soluciones de cifrado se incorporaron por primera vez para garantizar la seguridad, integridad y confidencialidad de los contextos de transmisión a través de cables sin seguridad o medios inalámbricos. Debido a las restricciones de potencia de cálculo antes de la era del ordenador, la técnica de cifrado simple era un método más que suficiente para ocultar la información. Sin embargo, algunas vulnerabilidades algorítmicas pueden ser explotadas para restaurar la regla de codificación sin mucho esfuerzo. Esto ha motivado nuevas investigaciones en el área de la criptografía, con el fin de proteger el sistema de información ante sofisticados algoritmos. Con la invención de los ordenadores se ha acelerado en gran medida la implementación de criptografía segura, que ofrece resistencia eficiente encaminada a obtener mayores capacidades de computación altamente reforzadas. Igualmente, sofisticados cripto-análisis han impulsado las tecnologías de computación. Hoy en día, el mundo de la información ha estado involucrado con el campo de la criptografía, enfocada a proteger cualquier campo a través de diversas soluciones de cifrado. Estos enfoques se han fortalecido debido a la unificación optimizada de teorías matemáticas modernas y prácticas eficaces de hardware, siendo posible su implementación en varias plataformas (microprocesador, ASIC, FPGA, etc.). Las necesidades y requisitos de seguridad en la industria son las principales métricas de conducción en el diseño electrónico, con el objetivo de promover la fabricación de productos de gran alcance sin sacrificar la seguridad de los clientes. Sin embargo, una vulnerabilidad en la implementación práctica encontrada por el Prof. Paul Kocher, et al en 1996 implica que un circuito digital es inherentemente vulnerable a un ataque no convencional, lo cual fue nombrado posteriormente como ataque de canal lateral, debido a su fuente de análisis. Sin embargo, algunas críticas sobre los algoritmos criptográficos teóricamente seguros surgieron casi inmediatamente después de este descubrimiento. En este sentido, los circuitos digitales consisten típicamente en un gran número de celdas lógicas fundamentales (como MOS - Metal Oxide Semiconductor), construido sobre un sustrato de silicio durante la fabricación. La lógica de los circuitos se realiza en función de las innumerables conmutaciones de estas células. Este mecanismo provoca inevitablemente cierta emanación física especial que puede ser medida y correlacionada con el comportamiento interno del circuito. SCA se puede utilizar para revelar datos confidenciales (por ejemplo, la criptografía de claves), analizar la arquitectura lógica, el tiempo e incluso inyectar fallos malintencionados a los circuitos que se implementan en sistemas embebidos, como FPGAs, ASICs, o tarjetas inteligentes. Mediante el uso de la comparación de correlación entre la cantidad de fuga estimada y las fugas medidas de forma real, información confidencial puede ser reconstruida en mucho menos tiempo y computación. Para ser precisos, SCA básicamente cubre una amplia gama de tipos de ataques, como los análisis de consumo de energía y radiación ElectroMagnética (EM). Ambos se basan en análisis estadístico y, por lo tanto, requieren numerosas muestras. Los algoritmos de cifrado no están intrínsecamente preparados para ser resistentes ante SCA. Es por ello que se hace necesario durante la implementación de circuitos integrar medidas que permitan camuflar las fugas a través de "canales laterales". Las medidas contra SCA están evolucionando junto con el desarrollo de nuevas técnicas de ataque, así como la continua mejora de los dispositivos electrónicos. Las características físicas requieren contramedidas sobre la capa física, que generalmente se pueden clasificar en soluciones intrínsecas y extrínsecas. Contramedidas extrínsecas se ejecutan para confundir la fuente de ataque mediante la integración de ruido o mala alineación de la actividad interna. Comparativamente, las contramedidas intrínsecas están integradas en el propio algoritmo, para modificar la aplicación con el fin de minimizar las fugas medibles, o incluso hacer que dichas fugas no puedan ser medibles. Ocultación y Enmascaramiento son dos técnicas típicas incluidas en esta categoría. Concretamente, el enmascaramiento se aplica a nivel algorítmico, para alterar los datos intermedios sensibles con una máscara de manera reversible. A diferencia del enmascaramiento lineal, las operaciones no lineales que ampliamente existen en criptografías modernas son difíciles de enmascarar. Dicho método de ocultación, que ha sido verificado como una solución efectiva, comprende principalmente la codificación en doble carril, que está ideado especialmente para aplanar o eliminar la fuga dependiente de dato en potencia o en EM. En esta tesis doctoral, además de la descripción de las metodologías de ataque, se han dedicado grandes esfuerzos sobre la estructura del prototipo de la lógica propuesta, con el fin de realizar investigaciones enfocadas a la seguridad sobre contramedidas de arquitectura a nivel lógico. Una característica de SCA reside en el formato de las fuentes de fugas. Un típico ataque de canal lateral se refiere al análisis basado en la potencia, donde la capacidad fundamental del transistor MOS y otras capacidades parásitas son las fuentes esenciales de fugas. Por lo tanto, una lógica robusta resistente a SCA debe eliminar o mitigar las fugas de estas micro-unidades, como las puertas lógicas básicas, los puertos I/O y las rutas. Las herramientas EDA proporcionadas por los vendedores manipulan la lógica desde un nivel más alto, en lugar de realizarlo desde el nivel de puerta, donde las fugas de canal lateral se manifiestan. Por lo tanto, las implementaciones clásicas apenas satisfacen estas necesidades e inevitablemente atrofian el prototipo. Por todo ello, la implementación de un esquema de diseño personalizado y flexible ha de ser tomado en cuenta. En esta tesis se presenta el diseño y la implementación de una lógica innovadora para contrarrestar SCA, en la que se abordan 3 aspectos fundamentales: I. Se basa en ocultar la estrategia sobre el circuito en doble carril a nivel de puerta para obtener dinámicamente el equilibrio de las fugas en las capas inferiores; II. Esta lógica explota las características de la arquitectura de las FPGAs, para reducir al mínimo el gasto de recursos en la implementación; III. Se apoya en un conjunto de herramientas asistentes personalizadas, incorporadas al flujo genérico de diseño sobre FPGAs, con el fin de manipular los circuitos de forma automática. El kit de herramientas de diseño automático es compatible con la lógica de doble carril propuesta, para facilitar la aplicación práctica sobre la familia de FPGA del fabricante Xilinx. En este sentido, la metodología y las herramientas son flexibles para ser extendido a una amplia gama de aplicaciones en las que se desean obtener restricciones mucho más rígidas y sofisticadas a nivel de puerta o rutado. En esta tesis se realiza un gran esfuerzo para facilitar el proceso de implementación y reparación de lógica de doble carril genérica. La viabilidad de las soluciones propuestas es validada mediante la selección de algoritmos criptográficos ampliamente utilizados, y su evaluación exhaustiva en comparación con soluciones anteriores. Todas las propuestas están respaldadas eficazmente a través de ataques experimentales con el fin de validar las ventajas de seguridad del sistema. El presente trabajo de investigación tiene la intención de cerrar la brecha entre las barreras de implementación y la aplicación efectiva de lógica de doble carril. En esencia, a lo largo de esta tesis se describirá un conjunto de herramientas de implementación para FPGAs que se han desarrollado para trabajar junto con el flujo de diseño genérico de las mismas, con el fin de lograr crear de forma innovadora la lógica de doble carril. Un nuevo enfoque en el ámbito de la seguridad en el cifrado se propone para obtener personalización, automatización y flexibilidad en el prototipo de circuito de bajo nivel con granularidad fina. Las principales contribuciones del presente trabajo de investigación se resumen brevemente a continuación: Lógica de Precharge Absorbed-DPL logic: El uso de la conversión de netlist para reservar LUTs libres para ejecutar la señal de precharge y Ex en una lógica DPL. Posicionamiento entrelazado Row-crossed con pares idénticos de rutado en redes de doble carril, lo que ayuda a aumentar la resistencia frente a la medición EM selectiva y mitigar los impactos de las variaciones de proceso. Ejecución personalizada y herramientas de conversión automática para la generación de redes idénticas para la lógica de doble carril propuesta. (a) Para detectar y reparar conflictos en las conexiones; (b) Detectar y reparar las rutas asimétricas. (c) Para ser utilizado en otras lógicas donde se requiere un control estricto de las interconexiones en aplicaciones basadas en Xilinx. Plataforma CPA de pruebas personalizadas para el análisis de EM y potencia, incluyendo la construcción de dicha plataforma, el método de medición y análisis de los ataques. Análisis de tiempos para cuantificar los niveles de seguridad. División de Seguridad en la conversión parcial de un sistema de cifrado complejo para reducir los costes de la protección. Prueba de concepto de un sistema de calefacción auto-adaptativo para mitigar los impactos eléctricos debido a la variación del proceso de silicio de manera dinámica. La presente tesis doctoral se encuentra organizada tal y como se detalla a continuación: En el capítulo 1 se abordan los fundamentos de los ataques de canal lateral, que abarca desde conceptos básicos de teoría de modelos de análisis, además de la implementación de la plataforma y la ejecución de los ataques. En el capítulo 2 se incluyen las estrategias de resistencia SCA contra los ataques de potencia diferencial y de EM. Además de ello, en este capítulo se propone una lógica en doble carril compacta y segura como contribución de gran relevancia, así como también se presentará la transformación lógica basada en un diseño a nivel de puerta. Por otra parte, en el Capítulo 3 se abordan los desafíos relacionados con la implementación de lógica en doble carril genérica. Así mismo, se describirá un flujo de diseño personalizado para resolver los problemas de aplicación junto con una herramienta de desarrollo automático de aplicaciones propuesta, para mitigar las barreras de diseño y facilitar los procesos. En el capítulo 4 se describe de forma detallada la elaboración e implementación de las herramientas propuestas. Por otra parte, la verificación y validaciones de seguridad de la lógica propuesta, así como un sofisticado experimento de verificación de la seguridad del rutado, se describen en el capítulo 5. Por último, un resumen de las conclusiones de la tesis y las perspectivas como líneas futuras se incluyen en el capítulo 6. Con el fin de profundizar en el contenido de la tesis doctoral, cada capítulo se describe de forma más detallada a continuación: En el capítulo 1 se introduce plataforma de implementación hardware además las teorías básicas de ataque de canal lateral, y contiene principalmente: (a) La arquitectura genérica y las características de la FPGA a utilizar, en particular la Xilinx Virtex-5; (b) El algoritmo de cifrado seleccionado (un módulo comercial Advanced Encryption Standard (AES)); (c) Los elementos esenciales de los métodos de canal lateral, que permiten revelar las fugas de disipación correlacionadas con los comportamientos internos; y el método para recuperar esta relación entre las fluctuaciones físicas en los rastros de canal lateral y los datos internos procesados; (d) Las configuraciones de las plataformas de pruebas de potencia / EM abarcadas dentro de la presente tesis. El contenido de esta tesis se amplia y profundiza a partir del capítulo 2, en el cual se abordan varios aspectos claves. En primer lugar, el principio de protección de la compensación dinámica de la lógica genérica de precarga de doble carril (Dual-rail Precharge Logic-DPL) se explica mediante la descripción de los elementos compensados a nivel de puerta. En segundo lugar, la lógica PA-DPL es propuesta como aportación original, detallando el protocolo de la lógica y un caso de aplicación. En tercer lugar, dos flujos de diseño personalizados se muestran para realizar la conversión de doble carril. Junto con ello, se aclaran las definiciones técnicas relacionadas con la manipulación por encima de la netlist a nivel de LUT. Finalmente, una breve discusión sobre el proceso global se aborda en la parte final del capítulo. El Capítulo 3 estudia los principales retos durante la implementación de DPLs en FPGAs. El nivel de seguridad de las soluciones de resistencia a SCA encontradas en el estado del arte se ha degenerado debido a las barreras de implantación a través de herramientas EDA convencionales. En el escenario de la arquitectura FPGA estudiada, se discuten los problemas de los formatos de doble carril, impactos parásitos, sesgo tecnológico y la viabilidad de implementación. De acuerdo con estas elaboraciones, se plantean dos problemas: Cómo implementar la lógica propuesta sin penalizar los niveles de seguridad, y cómo manipular un gran número de celdas y automatizar el proceso. El PA-DPL propuesto en el capítulo 2 se valida con una serie de iniciativas, desde características estructurales como doble carril entrelazado o redes de rutado clonadas, hasta los métodos de aplicación tales como las herramientas de personalización y automatización de EDA. Por otra parte, un sistema de calefacción auto-adaptativo es representado y aplicado a una lógica de doble núcleo, con el fin de ajustar alternativamente la temperatura local para equilibrar los impactos negativos de la variación del proceso durante la operación en tiempo real. El capítulo 4 se centra en los detalles de la implementación del kit de herramientas. Desarrollado sobre una API third-party, el kit de herramientas personalizado es capaz de manipular los elementos de la lógica de circuito post P&R ncd (una versión binaria ilegible del xdl) convertido al formato XDL Xilinx. El mecanismo y razón de ser del conjunto de instrumentos propuestos son cuidadosamente descritos, que cubre la detección de enrutamiento y los enfoques para la reparación. El conjunto de herramientas desarrollado tiene como objetivo lograr redes de enrutamiento estrictamente idénticos para la lógica de doble carril, tanto para posicionamiento separado como para el entrelazado. Este capítulo particularmente especifica las bases técnicas para apoyar las implementaciones en los dispositivos de Xilinx y su flexibilidad para ser utilizado sobre otras aplicaciones. El capítulo 5 se enfoca en la aplicación de los casos de estudio para la validación de los grados de seguridad de la lógica propuesta. Se discuten los problemas técnicos detallados durante la ejecución y algunas nuevas técnicas de implementación. (a) Se discute el impacto en el proceso de posicionamiento de la lógica utilizando el kit de herramientas propuesto. Diferentes esquemas de implementación, tomando en cuenta la optimización global en seguridad y coste, se verifican con los experimentos con el fin de encontrar los planes de posicionamiento y reparación optimizados; (b) las validaciones de seguridad se realizan con los métodos de correlación y análisis de tiempo; (c) Una táctica asintótica se aplica a un núcleo AES sobre BCDL estructurado para validar de forma sofisticada el impacto de enrutamiento sobre métricas de seguridad; (d) Los resultados preliminares utilizando el sistema de calefacción auto-adaptativa sobre la variación del proceso son mostrados; (e) Se introduce una aplicación práctica de las herramientas para un diseño de cifrado completa. Capítulo 6 incluye el resumen general del trabajo presentado dentro de esta tesis doctoral. Por último, una breve perspectiva del trabajo futuro se expone, lo que puede ampliar el potencial de utilización de las contribuciones de esta tesis a un alcance más allá de los dominios de la criptografía en FPGAs. ABSTRACT This PhD thesis mainly concentrates on countermeasure techniques related to the Side Channel Attack (SCA), which has been put forward to academic exploitations since 17 years ago. The related research has seen a remarkable growth in the past decades, while the design of solid and efficient protection still curiously remain as an open research topic where more reliable initiatives are required for personal information privacy, enterprise and national data protections. The earliest documented usage of secret code can be traced back to around 1700 B.C., when the hieroglyphs in ancient Egypt are scribed in inscriptions. Information security always gained serious attention from diplomatic or military intelligence transmission. Due to the rapid evolvement of modern communication technique, crypto solution was first incorporated by electronic signal to ensure the confidentiality, integrity, availability, authenticity and non-repudiation of the transmitted contexts over unsecure cable or wireless channels. Restricted to the computation power before computer era, simple encryption tricks were practically sufficient to conceal information. However, algorithmic vulnerabilities can be excavated to restore the encoding rules with affordable efforts. This fact motivated the development of modern cryptography, aiming at guarding information system by complex and advanced algorithms. The appearance of computers has greatly pushed forward the invention of robust cryptographies, which efficiently offers resistance relying on highly strengthened computing capabilities. Likewise, advanced cryptanalysis has greatly driven the computing technologies in turn. Nowadays, the information world has been involved into a crypto world, protecting any fields by pervasive crypto solutions. These approaches are strong because of the optimized mergence between modern mathematical theories and effective hardware practices, being capable of implement crypto theories into various platforms (microprocessor, ASIC, FPGA, etc). Security needs from industries are actually the major driving metrics in electronic design, aiming at promoting the construction of systems with high performance without sacrificing security. Yet a vulnerability in practical implementation found by Prof. Paul Kocher, et al in 1996 implies that modern digital circuits are inherently vulnerable to an unconventional attack approach, which was named as side-channel attack since then from its analysis source. Critical suspicions to theoretically sound modern crypto algorithms surfaced almost immediately after this discovery. To be specifically, digital circuits typically consist of a great number of essential logic elements (as MOS - Metal Oxide Semiconductor), built upon a silicon substrate during the fabrication. Circuit logic is realized relying on the countless switch actions of these cells. This mechanism inevitably results in featured physical emanation that can be properly measured and correlated with internal circuit behaviors. SCAs can be used to reveal the confidential data (e.g. crypto-key), analyze the logic architecture, timing and even inject malicious faults to the circuits that are implemented in hardware system, like FPGA, ASIC, smart Card. Using various comparison solutions between the predicted leakage quantity and the measured leakage, secrets can be reconstructed at much less expense of time and computation. To be precisely, SCA basically encloses a wide range of attack types, typically as the analyses of power consumption or electromagnetic (EM) radiation. Both of them rely on statistical analyses, and hence require a number of samples. The crypto algorithms are not intrinsically fortified with SCA-resistance. Because of the severity, much attention has to be taken into the implementation so as to assemble countermeasures to camouflage the leakages via "side channels". Countermeasures against SCA are evolving along with the development of attack techniques. The physical characteristics requires countermeasures over physical layer, which can be generally classified into intrinsic and extrinsic vectors. Extrinsic countermeasures are executed to confuse the attacker by integrating noise, misalignment to the intra activities. Comparatively, intrinsic countermeasures are built into the algorithm itself, to modify the implementation for minimizing the measurable leakage, or making them not sensitive any more. Hiding and Masking are two typical techniques in this category. Concretely, masking applies to the algorithmic level, to alter the sensitive intermediate values with a mask in reversible ways. Unlike the linear masking, non-linear operations that widely exist in modern cryptographies are difficult to be masked. Approved to be an effective counter solution, hiding method mainly mentions dual-rail logic, which is specially devised for flattening or removing the data-dependent leakage in power or EM signatures. In this thesis, apart from the context describing the attack methodologies, efforts have also been dedicated to logic prototype, to mount extensive security investigations to countermeasures on logic-level. A characteristic of SCA resides on the format of leak sources. Typical side-channel attack concerns the power based analysis, where the fundamental capacitance from MOS transistors and other parasitic capacitances are the essential leak sources. Hence, a robust SCA-resistant logic must eliminate or mitigate the leakages from these micro units, such as basic logic gates, I/O ports and routings. The vendor provided EDA tools manipulate the logic from a higher behavioral-level, rather than the lower gate-level where side-channel leakage is generated. So, the classical implementations barely satisfy these needs and inevitably stunt the prototype. In this case, a customized and flexible design scheme is appealing to be devised. This thesis profiles an innovative logic style to counter SCA, which mainly addresses three major aspects: I. The proposed logic is based on the hiding strategy over gate-level dual-rail style to dynamically overbalance side-channel leakage from lower circuit layer; II. This logic exploits architectural features of modern FPGAs, to minimize the implementation expenses; III. It is supported by a set of assistant custom tools, incorporated by the generic FPGA design flow, to have circuit manipulations in an automatic manner. The automatic design toolkit supports the proposed dual-rail logic, facilitating the practical implementation on Xilinx FPGA families. While the methodologies and the tools are flexible to be expanded to a wide range of applications where rigid and sophisticated gate- or routing- constraints are desired. In this thesis a great effort is done to streamline the implementation workflow of generic dual-rail logic. The feasibility of the proposed solutions is validated by selected and widely used crypto algorithm, for thorough and fair evaluation w.r.t. prior solutions. All the proposals are effectively verified by security experiments. The presented research work attempts to solve the implementation troubles. The essence that will be formalized along this thesis is that a customized execution toolkit for modern FPGA systems is developed to work together with the generic FPGA design flow for creating innovative dual-rail logic. A method in crypto security area is constructed to obtain customization, automation and flexibility in low-level circuit prototype with fine-granularity in intractable routings. Main contributions of the presented work are summarized next: Precharge Absorbed-DPL logic: Using the netlist conversion to reserve free LUT inputs to execute the Precharge and Ex signal in a dual-rail logic style. A row-crossed interleaved placement method with identical routing pairs in dual-rail networks, which helps to increase the resistance against selective EM measurement and mitigate the impacts from process variations. Customized execution and automatic transformation tools for producing identical networks for the proposed dual-rail logic. (a) To detect and repair the conflict nets; (b) To detect and repair the asymmetric nets. (c) To be used in other logics where strict network control is required in Xilinx scenario. Customized correlation analysis testbed for EM and power attacks, including the platform construction, measurement method and attack analysis. A timing analysis based method for quantifying the security grades. A methodology of security partitions of complex crypto systems for reducing the protection cost. A proof-of-concept self-adaptive heating system to mitigate electrical impacts over process variations in dynamic dual-rail compensation manner. The thesis chapters are organized as follows: Chapter 1 discusses the side-channel attack fundamentals, which covers from theoretic basics to analysis models, and further to platform setup and attack execution. Chapter 2 centers to SCA-resistant strategies against generic power and EM attacks. In this chapter, a major contribution, a compact and secure dual-rail logic style, will be originally proposed. The logic transformation based on bottom-layer design will be presented. Chapter 3 is scheduled to elaborate the implementation challenges of generic dual-rail styles. A customized design flow to solve the implementation problems will be described along with a self-developed automatic implementation toolkit, for mitigating the design barriers and facilitating the processes. Chapter 4 will originally elaborate the tool specifics and construction details. The implementation case studies and security validations for the proposed logic style, as well as a sophisticated routing verification experiment, will be described in Chapter 5. Finally, a summary of thesis conclusions and perspectives for future work are included in Chapter 5. To better exhibit the thesis contents, each chapter is further described next: Chapter 1 provides the introduction of hardware implementation testbed and side-channel attack fundamentals, and mainly contains: (a) The FPGA generic architecture and device features, particularly of Virtex-5 FPGA; (b) The selected crypto algorithm - a commercially and extensively used Advanced Encryption Standard (AES) module - is detailed; (c) The essentials of Side-Channel methods are profiled. It reveals the correlated dissipation leakage to the internal behaviors, and the method to recover this relationship between the physical fluctuations in side-channel traces and the intra processed data; (d) The setups of the power/EM testing platforms enclosed inside the thesis work are given. The content of this thesis is expanded and deepened from chapter 2, which is divided into several aspects. First, the protection principle of dynamic compensation of the generic dual-rail precharge logic is explained by describing the compensated gate-level elements. Second, the novel DPL is originally proposed by detailing the logic protocol and an implementation case study. Third, a couple of custom workflows are shown next for realizing the rail conversion. Meanwhile, the technical definitions that are about to be manipulated above LUT-level netlist are clarified. A brief discussion about the batched process is given in the final part. Chapter 3 studies the implementation challenges of DPLs in FPGAs. The security level of state-of-the-art SCA-resistant solutions are decreased due to the implementation barriers using conventional EDA tools. In the studied FPGA scenario, problems are discussed from dual-rail format, parasitic impact, technological bias and implementation feasibility. According to these elaborations, two problems arise: How to implement the proposed logic without crippling the security level; and How to manipulate a large number of cells and automate the transformation. The proposed PA-DPL in chapter 2 is legalized with a series of initiatives, from structures to implementation methods. Furthermore, a self-adaptive heating system is depicted and implemented to a dual-core logic, assumed to alternatively adjust local temperature for balancing the negative impacts from silicon technological biases on real-time. Chapter 4 centers to the toolkit system. Built upon a third-party Application Program Interface (API) library, the customized toolkit is able to manipulate the logic elements from post P&R circuit (an unreadable binary version of the xdl one) converted to Xilinx xdl format. The mechanism and rationale of the proposed toolkit are carefully convoyed, covering the routing detection and repairing approaches. The developed toolkit aims to achieve very strictly identical routing networks for dual-rail logic both for separate and interleaved placement. This chapter particularly specifies the technical essentials to support the implementations in Xilinx devices and the flexibility to be expanded to other applications. Chapter 5 focuses on the implementation of the case studies for validating the security grades of the proposed logic style from the proposed toolkit. Comprehensive implementation techniques are discussed. (a) The placement impacts using the proposed toolkit are discussed. Different execution schemes, considering the global optimization in security and cost, are verified with experiments so as to find the optimized placement and repair schemes; (b) Security validations are realized with correlation, timing methods; (c) A systematic method is applied to a BCDL structured module to validate the routing impact over security metric; (d) The preliminary results using the self-adaptive heating system over process variation is given; (e) A practical implementation of the proposed toolkit to a large design is introduced. Chapter 6 includes the general summary of the complete work presented inside this thesis. Finally, a brief perspective for the future work is drawn which might expand the potential utilization of the thesis contributions to a wider range of implementation domains beyond cryptography on FPGAs.

Construction cost and energy consumption resulting from energy retrofitting in an apartment building in Madrid (Spain).

This theoretical study analyzes the relation between the measures necessesary for the energy retrofitting of a residential building constructed in Madrid, their cost and the improvement of the energy rating of the dwellings. The aim of this work is to establish an evaluation methodology that allows developers and architects to obtain conclusions and orientates therm in the decisioin-making process. It will allow finding the most suitable cost-effective solutions in each case. This paper describes the methodology and the findings obtained. Energy retrofitting and the improvement of the energy behaviour of the building depend on the selection of the retrofitting solutions and also on the investment. In this case study to achieve the best energy rates it is necessary to improve the thermal performance of the envelope as well as the energy systems. Energy retrofitting means an increase in property value but it can't only be considered in economic terms. It is necessary to take into account unquantifiable aspects as increased comfort, improved sound insulation, livability, health, or the elimination of energy poverty situations.

Energy Storage Systems for Electric Vehicles: Performance Comparison based on a Simple Equivalent Circuit and Experimental Tests

The decision to select the most suitable type of energy storage system for an electric vehicle is always difficult, since many conditionings must be taken into account. Sometimes, this study can be made by means of complex mathematical models which represent the behavior of a battery, ultracapacitor or some other devices. However, these models are usually too dependent on parameters that are not easily available, which usually results in nonrealistic results. Besides, the more accurate the model, the more specific it needs to be, which becomes an issue when comparing systems of different nature. This paper proposes a practical methodology to compare different energy storage technologies. This is done by means of a linear approach of an equivalent circuit based on laboratory tests. Via these tests, the internal resistance and the self-discharge rate are evaluated, making it possible to compare different energy storage systems regardless their technology. Rather simple testing equipment is sufficient to give a comparative idea of the differences between each system, concerning issues such as efficiency, heating and self-discharge, when operating under a certain scenario. The proposed methodology is applied to four energy storage systems of different nature for the sake of illustration.

Building a decision support system with a knowledge modeling tool

Knowledge modeling tools are software tools that follow a modeling approach to help developers in building a knowledge-based system. The purpose of this article is to show the advantages of using this type of tools in the development of complex knowledge-based decision support systems. In order to do so, the article describes the development of a system called SAIDA in the domain of hydrology with the help of the KSM modeling tool. SAIDA operates on real-time receiving data recorded by sensors (rainfall, water levels, flows, etc.). It follows a multi-agent architecture to interpret the data, predict the future behavior and recommend control actions. The system includes an advanced knowledge based architecture with multiple symbolic representation. KSM was especially useful to design and implement the complex knowledge based architecture in an efficient way.

Methodology for estimating building integrated photovoltaics electricity production under shadowing conditions and case study

Building integrated photovoltaic (BIPV) systems are a relevant application of photovoltaics. In countries belonging to the International Energy Agency countries, 24% of total installed PV power corresponds to BIPV systems. Electricity losses caused by shadows over the PV generator have a significant impact on the performance of BIPV systems, being the major source of electricity losses. This paper presents a methodology to estimate electricity produced by BIPV systems which incorporates a model for shading losses. The proposed methodology has been validated on a one year study with real data from two similar PV systems placed on the south façade of a building belonging to the Technical University of Madrid. This study has covered all weather conditions: clear, partially overcast and fully overcast sky. Results of this study are shown at different time scales, resulting that the errors committed by the best performing model are below 1% and 3% in annual and daily electricity estimation. The use of models which account for the reduced performance at low irradiance levels also improves the estimation of generated electricity.

Building resilience to water scarcity in Southern Spain: A case study of rice farming in Doñana protected wetlands

Agricultural water management needs to evolve in view of increased water scarcity, especially when farming and natural protected areas are closely linked. In the study site of Don?ana (southern Spain), water is shared by rice producers and a world heritage biodiversity ecosystem. Our aim is to contribute to defining adaptation strategies that may build resilience to increasing water scarcity and minimize water conflicts among agricultural and natural systems. The analytical framework links a participatory process with quantitative methods to prioritize the adaptation options. Bottom-up proposed adaptation measures are evaluated by a multi-criteria analysis (MCA) that includes both socioeconomic criteria and criteria of the ecosystem services affected by the adaptation options. Criteria weights are estimated by three different methods?analytic hierarchy process, Likert scale and equal weights?that are then compared. Finally, scores from an MCA are input into an optimization model used to determine the optimal land-use distribution in order to maximize utility and land-use diversification according to different scenarios of funds and water availability. While our results show a spectrum of perceptions of priorities among stakeholders, there is one overriding theme that is to define a way to restore part of the rice fields to natural wetlands. These results hold true under the current climate scenario and evenmore so under an increased water scarcity scenario.

Building memristor applications: from device model to circuit design

Since the memristor was first built in 2008 at HP Labs, no end of devices and models have been presented. Also, new applications appear frequently. However, the integration of the device at the circuit level is not straightforward, because available models are still immature and/or suppose high computational loads, making their simulation long and cumbersome. This study assists circuit/systems designers in the integration of memristors in their applications, while aiding model developers in the validation of their proposals. We introduce the use of a memristor application framework to support the work of both the model developer and the circuit designer. First, the framework includes a library with the best-known memristor models, being easily extensible with upcoming models. Systematic modifications have been applied to these models to provide better convergence and significant simulations speedups. Second, a quick device simulator allows the study of the response of the models under different scenarios, helping the designer with the stimuli and operation time selection. Third, fine tuning of the device including parameters variations and threshold determination is also supported. Finally, SPICE/Spectre subcircuit generation is provided to ease the integration of the devices in application circuits. The framework provides the designer with total control overconvergence, computational load, and the evolution of system variables, overcoming usual problems in the integration of memristive devices.

Building an ontology catalogue for smart cities

Apart from providing semantics and reasoning power to data, ontologies enable and facilitate interoperability across heterogeneous systems or environments. A good practice when developing ontologies is to reuse as much knowledge as possible in order to increase interoperability by reducing heterogeneity across models and to reduce development effort. Ontology registries, indexes and catalogues facilitate the task of finding, exploring and reusing ontologies by collecting them from different sources. This paper presents an ontology catalogue for the smart cities and related domains. This catalogue is based on curated metadata and incorporates ontology evaluation features. Such catalogue represents the first approach within this community and it would be highly useful for new ontology developments or for describing and annotating existing ontologies.

Analysis of the suitability of existing medical ontologies for building a scalable semantic interoperability solution supporting multi-site collaboration in oncology

Semantic interoperability is essential to facilitate efficient collaboration in heterogeneous multi-site healthcare environments. The deployment of a semantic interoperability solution has the potential to enable a wide range of informatics supported applications in clinical care and research both within as ingle healthcare organization and in a network of organizations. At the same time, building and deploying a semantic interoperability solution may require significant effort to carryout data transformation and to harmonize the semantics of the information in the different systems. Our approach to semantic interoperability leverages existing healthcare standards and ontologies, focusing first on specific clinical domains and key applications, and gradually expanding the solution when needed. An important objective of this work is to create a semantic link between clinical research and care environments to enable applications such as streamlining the execution of multi-centric clinical trials, including the identification of eligible patients for the trials. This paper presents an analysis of the suitability of several widely-used medical ontologies in the clinical domain: SNOMED-CT, LOINC, MedDRA, to capture the semantics of the clinical trial eligibility criteria, of the clinical trial data (e.g., Clinical Report Forms), and of the corresponding patient record data that would enable the automatic identification of eligible patients. Next to the coverage provided by the ontologies we evaluate and compare the sizes of the sets of relevant concepts and their relative frequency to estimate the cost of data transformation, of building the necessary semantic mappings, and of extending the solution to new domains. This analysis shows that our approach is both feasible and scalable.