NFC based remote control of services for interactive spaces

Ubiquitous computing (one person, many computers) is the third era in the history of computing. It follows the mainframe era (many people, one computer) and the PC era (one person, one computer). Ubiquitous computing empowers people to communicate with services by interacting with their surroundings. Most of these so called smart environments contain sensors sensing users’ actions and try to predict the users’ intentions and necessities based on sensor data. The main drawback of this approach is that the system might perform unexpected or unwanted actions, making the user feel out of control. In this master thesis we propose a different procedure based on Interactive Spaces: instead of predicting users’ intentions based on sensor data, the system reacts to users’ explicit predefined actions. To that end, we present REACHeS, a server platform which enables communication among services, resources and users located in the same environment. With REACHeS, a user controls services and resources by interacting with everyday life objects and using a mobile phone as a mediator between himself/herself, the system and the environment. REACHeS’ interfaces with a user are built upon NFC (Near Field Communication) technology. NFC tags are attached to objects in the environment. A tag stores commands that are sent to services when a user touches the tag with his/her NFC enabled device. The prototypes and usability tests presented in this thesis show the great potential of NFC to build such user interfaces.

STONE: a stream-based DDoS defense framework

An effective Distributed Denial of Service (DDoS) defense mechanism must guarantee legitimate users access to an Internet service masking the effects of possible attacks. That is, it must be able to detect threats and discard malicious packets in a online fashion. Given that emerging data streaming technology can enable such mitigation in an effective manner, in this paper we present STONE, a stream-based DDoS defense framework, which integrates anomaly-based DDoS detection and mitigation with scalable data streaming technology. With STONE, the traffic of potential targets is analyzed via continuous data streaming queries maintaining information used for both attack detection and mitigation. STONE provides minimal degradation of legitimate users traffic during DDoS attacks and it also faces effectively flash crowds. Our preliminary evaluation based on an implemented prototype and conducted with real legitimate and malicious traffic traces shows that STONE is able to provide fast detection and precise mitigation of DDoS attacks leveraging scalable data streaming technology.

FPGA-Based Wireless Sensor Node Architecture for High Performance Applications

While for years traditional wireless sensor nodes have been based on ultra-low power microcontrollers with sufficient but limited computing power, the complexity and number of tasks of today’s applications are constantly increasing. Increasing the node duty cycle is not feasible in all cases, so in many cases more computing power is required. This extra computing power may be achieved by either more powerful microcontrollers, though more power consumption or, in general, any solution capable of accelerating task execution. At this point, the use of hardware based, and in particular FPGA solutions, might appear as a candidate technology, since though power use is higher compared with lower power devices, execution time is reduced, so energy could be reduced overall. In order to demonstrate this, an innovative WSN node architecture is proposed. This architecture is based on a high performance high capacity state-of-the-art FPGA, which combines the advantages of the intrinsic acceleration provided by the parallelism of hardware devices, the use of partial reconfiguration capabilities, as well as a careful power-aware management system, to show that energy savings for certain higher-end applications can be achieved. Finally, comprehensive tests have been done to validate the platform in terms of performance and power consumption, to proof that better energy efficiency compared to processor based solutions can be achieved, for instance, when encryption is imposed by the application requirements.

Efficient hybrid monocular-stereo approach to on-board, video-based traffic sign detection and tracking

In this paper we propose an innovative method for the automatic detection and tracking of road traffic signs using an onboard stereo camera. It involves a combination of monocular and stereo analysis strategies to increase the reliability of the detections such that it can boost the performance of any traffic sign recognition scheme. Firstly, an adaptive color and appearance based detection is applied at single camera level to generate a set of traffic sign hypotheses. In turn, stereo information allows for sparse 3D reconstruction of potential traffic signs through a SURF-based matching strategy. Namely, the plane that best fits the cloud of 3D points traced back from feature matches is estimated using a RANSAC based approach to improve robustness to outliers. Temporal consistency of the 3D information is ensured through a Kalman-based tracking stage. This also allows for the generation of a predicted 3D traffic sign model, which is in turn used to enhance the previously mentioned color-based detector through a feedback loop, thus improving detection accuracy. The proposed solution has been tested with real sequences under several illumination conditions and in both urban areas and highways, achieving very high detection rates in challenging environments, including rapid motion and significant perspective distortion

CloudRoom: módulo de gestión de cursos online, abiertos y masivos

La razón de este proyecto, es la de desarrollar el módulo de cursos de la plataforma de Massive Online Open Courses (MOOCs), CloudRoom. Dicho módulo está englobado en una arquitectura orientada a servicios (SOA) y en una infraestructura de Cloud Computing utilizando Amazon Web Services (AWS). Nuestro objetivo es el de diseñar un Software as a Service (SaaS) robusto con las cualidades que a un producto de este tipo se le estiman: alta disponibilidad, alto rendimiento, gran experiencia de usuario y gran extensibilidad del sistema. Para lograrlo, se llevará a cabo la integración de las últimas tendencias tecnológicas dentro del desarrollo de sistemas distribuidos como Neo4j, Node.JS, Servicios RESTful, CoffeeScript. Todo esto siguiendo un estrategia de desarrollo PLAN-DO-CHECK utilizando Scrum y prácticas de metodologías ágiles. ---ABSTRACT---The reason of this Project is to develop the courses‟ module of CloudRoom, a Massive Online Open Courses platform. This module is encapsulated in a service-oriented architecture (SOA) based on a Cloud Computing infrastructure built on Amazon Web Services (AWS). Our goal is to design a robust Software as a Service (SaaS) with the qualities that are estimated in a product of this type: high availability, high performance, great user experience and great extensibility of the system. In order to address this, we carry out the integration of the latest technology trends in the development of distributed systems: Neo4j, Node.JS, RESTful Services and CoffeeScript. All of this, following a development strategy PLAN-DO-CHECK, using Scrum and practices of agile methodologies.

Sistema de monitorización de sistemas distribuidos

La computación distribuida ha estado presente desde hace unos cuantos años, pero es quizás en la actualidad cuando está contando con una mayor repercusión. En los últimos años el modelo de computación en la nube (Cloud computing) ha ganado mucha popularidad, prueba de ello es la cantidad de productos existentes. Todo sistema informático requiere ser controlado a través de sistemas de monitorización que permiten conocer el estado del mismo, de tal manera que pueda ser gestionado fácilmente. Hoy en día la mayoría de los productos de monitorización existentes limitan a la hora de visualizar una representación real de la arquitectura de los sistemas a monitorizar, lo que puede dificultar la tarea de los administradores. Es decir, la visualización que proporcionan de la arquitectura del sistema, en muchos casos se ve influenciada por el diseño del sistema de visualización, lo que impide ver los niveles de la arquitectura y las relaciones entre estos. En este trabajo se presenta un sistema de monitorización para sistemas distribuidos o Cloud, que pretende dar solución a esta problemática, no limitando la representación de la arquitectura del sistema a monitorizar. El sistema está formado por: agentes, que se encargan de la tarea de recolección de las métricas del sistema monitorizado; un servidor, al que los agentes le envían las métricas para que las almacenen en una base de datos; y una aplicación web, a través de la que se visualiza toda la información. El sistema ha sido probado satisfactoriamente con la monitorización de CumuloNimbo, una plataforma como servicio (PaaS), que ofrece interfaz SQL y procesamiento transaccional altamente escalable sobre almacenes clave valor. Este trabajo describe la arquitectura del sistema de monitorización, y en concreto, el desarrollo de la principal contribución al sistema, la aplicación web. ---ABSTRACT---Distributed computing has been around for quite a long time, but now it is becoming more and more important. In the last few years, cloud computing, a branch of distributed computing has become very popular, as its different products in the market can prove. Every computing system requires to be controlled through monitoring systems to keep them functioning correctly. Currently, most of the monitoring systems in the market only provide a view of the architectures of the systems monitored, which in most cases do not permit having a real view of the system. This lack of vision can make administrators’ tasks really difficult. If they do not know the architecture perfectly, controlling the system based on the view that the monitoring system provides is extremely complicated. The project introduces a new monitoring system for distributed or Cloud systems, which shows the real architecture of the system. This new system is composed of several elements: agents, which collect the metrics of the monitored system; a server, which receives the metrics from the agents and saves them in a database; and a web application, which shows all the data collected in an easy way. The monitoring system has been tested successfully with Cumulonimbo. CumuloNimbo is a platform as a service (PaaS) which offers an SQL interface and a high-scalable transactional process. This platform works over key-value storage. This project describes the architecture of the monitoring system, especially, the development of the web application, which is the main contribution to the system.

Implementación de una herramienta de productividad para el desarrollo y despliegue de aplicaciones

En la actualidad se está viviendo el auge del Cloud Computing (Computación en la Nube) y cada vez son más las empresas importantes en el sector de las Tecnologías de la Información que apuestan con fuerza por estos servicios. Por un lado, algunas ofrecen servicios, como Amazon y su sistema IaaS (Infrastructure as a Service) Amazon Web Services (AWS); por otro, algunas los utilizan, como ocurre en el caso de este proyecto, en el que Telefonica I+D hace uso de los servicios proporcionados por AWS para sus proyectos. Debido a este crecimiento en el uso de las aplicaciones distribuidas es importante tener en cuenta el papel que desempeñan los desarrolladores y administradores de sistemas que han de trabajar y mantener todas las máquinas remotas de uno o varios proyectos desde una única máquina local. El ayudar a realizar estas tareas de la forma más cómoda y automática posible es el objetivo principal de este proyecto. En concreto, el objetivo de este proyecto es el diseño y la implementación de una solución software que ayude a la productividad en el desarrollo y despliegue de aplicaciones en un conjunto de máquinas remotas desde una única máquina local, teniendo como base una prueba de concepto realizada anteriormente que prueba las funcionalidades más básicas de las librerías utilizadas para el desarrollo de la herramienta. A lo largo de este proyecto se han estudiado las diferentes alternativas que se encuentran en el mercado que ofrecen al menos parte de la soluci6n a los problemas abordados, pese a que los requisitos de la empresa indicaban que la herramienta debía implementarse de forma completa. Se estudió a fondo después la prueba de concepto de la que se partía para, con los conocimientos adquiridos sobre el tema, mejorarla cumpliendo los objetivos marcados. Tras el desarrollo y la implementaci6n completa de la herramienta se proponen posibles caminos a seguir en el futuro. ---ABSTRACT---Nowadays we are experiencing the rise of Cloud Computing and every day more and more important IT companies are betting hard for this kind of services. On one hand, some of these companies offer services such as Amazon IaaS (Infrastructure as a Service) system Amazon Web Services (AWS); on the other hand, some of them use these services, as in the case of this project, in which Telefonica I+D uses the services provided by AWS in their projects. Due this growth in the use of distributed applications it is important to consider the developers and system administrators' roles, who have to work and do the maintenance of all the remote machines from one or several projects from a single local machine. The main goal of this project is to help with these tasks making them as comfortable and automatically as possible. Specifically, the goal of this project is the design and implementation of a software solution that helps to achieve a better productivity in the development of applications on a set of remote machines from a single local machine, based on a proof of concept developed before, in which the basic functionality of the libraries used in this tool were tested. Throughout this project the different alternatives on the market that offer at least part of the solution to the problem addressed have been studied, although according to the requirements of the company, the tool should be implemented from scratch. After that, the basic proof of concept was thoroughly studied and improved with the knowledge acquired on the subject, fulfilling the marked goals. Once the development and full implementation of the tool is done, some ways of improvement for the future are suggested.

A sharing-based approach to supporting adaptation in service compositions

Data-related properties of the activities involved in a service composition can be used to facilitate several design-time and run-time adaptation tasks, such as service evolution, distributed enactment, and instance-level adaptation. A number of these properties can be expressed using a notion of sharing. We present an approach for automated inference of data properties based on sharing analysis, which is able to handle service compositions with complex control structures, involving loops and sub-workflows. The properties inferred can include data dependencies, information content, domain-defined attributes, privacy or confidentiality levels, among others. The analysis produces characterizations of the data and the activities in the composition in terms of minimal and maximal sharing, which can then be used to verify compliance of potential adaptation actions, or as supporting information in their generation. This sharing analysis approach can be used both at design time and at run time. In the latter case, the results of analysis can be refined using the composition traces (execution logs) at the point of execution, in order to support run-time adaptation.

Energy-based Fair Queuing: Energy-centric Processor Scheduling Algorithm for Battery-limited Mobile Systems

Los dispositivos móviles modernos disponen cada vez de más funcionalidad debido al rápido avance de las tecnologías de las comunicaciones y computaciones móviles. Sin embargo, la capacidad de la batería no ha experimentado un aumento equivalente. Por ello, la experiencia de usuario en los sistemas móviles modernos se ve muy afectada por la vida de la batería, que es un factor inestable de difícil de control. Para abordar este problema, investigaciones anteriores han propuesto un esquema de gestion del consumo (PM) centrada en la energía y que proporciona una garantía sobre la vida operativa de la batería mediante la gestión de la energía como un recurso de primera clase en el sistema. Como el planificador juega un papel fundamental en la administración del consumo de energía y en la garantía del rendimiento de las aplicaciones, esta tesis explora la optimización de la experiencia de usuario para sistemas móviles con energía limitada desde la perspectiva de un planificador que tiene en cuenta el consumo de energía en un contexto en el que ésta es un recurso de primera clase. En esta tesis se analiza en primer lugar los factores que contribuyen de forma general a la experiencia de usuario en un sistema móvil. Después se determinan los requisitos esenciales que afectan a la experiencia de usuario en la planificación centrada en el consumo de energía, que son el reparto proporcional de la potencia, el cumplimiento de las restricciones temporales, y cuando sea necesario, el compromiso entre la cuota de potencia y las restricciones temporales. Para cumplir con los requisitos, el algoritmo clásico de fair queueing y su modelo de referencia se extienden desde los dominios de las comunicaciones y ancho de banda de CPU hacia el dominio de la energía, y en base a ésto, se propone el algoritmo energy-based fair queueing (EFQ) para proporcionar una planificación basada en la energía. El algoritmo EFQ está diseñado para compartir la potencia consumida entre las tareas mediante su planificación en función de la energía consumida y de la cuota reservada. La cuota de consumo de cada tarea con restricciones temporales está protegida frente a diversos cambios que puedan ocurrir en el sistema. Además, para dar mejor soporte a las tareas en tiempo real y multimedia, se propone un mecanismo para combinar con el algoritmo EFQ para dar preferencia en la planificación durante breves intervalos de tiempo a las tareas más urgentes con restricciones temporales.Las propiedades del algoritmo EFQ se evaluan a través del modelado de alto nivel y la simulación. Los resultados de las simulaciones indican que los requisitos esenciales de la planificación centrada en la energía pueden lograrse. El algoritmo EFQ se implementa más tarde en el kernel de Linux. Para evaluar las propiedades del planificador EFQ basado en Linux, se desarrolló un banco de pruebas experimental basado en una sitema empotrado, un programa de banco de pruebas multihilo, y un conjunto de pruebas de código abierto. A través de experimentos específicamente diseñados, esta tesis verifica primero las propiedades de EFQ en la gestión de la cuota de consumo de potencia y la planificación en tiempo real y, a continuación, explora los beneficios potenciales de emplear la planificación EFQ en la optimización de la experiencia de usuario para sistemas móviles con energía limitada. Los resultados experimentales sobre la gestión de la cuota de energía muestran que EFQ es más eficaz que el planificador de Linux-CFS en la gestión de energía, logrando un reparto proporcional de la energía del sistema independientemente de en qué dispositivo se consume la energía. Los resultados experimentales en la planificación en tiempo real demuestran que EFQ puede lograr de forma eficaz, flexible y robusta el cumplimiento de las restricciones temporales aunque se dé el caso de aumento del el número de tareas o del error en la estimación de energía. Por último, un análisis comparativo de los resultados experimentales sobre la optimización de la experiencia del usuario demuestra que, primero, EFQ es más eficaz y flexible que los algoritmos tradicionales de planificación del procesador, como el que se encuentra por defecto en el planificador de Linux y, segundo, que proporciona la posibilidad de optimizar y preservar la experiencia de usuario para los sistemas móviles con energía limitada. Abstract Modern mobiledevices have been becoming increasingly powerful in functionality and entertainment as the next-generation mobile computing and communication technologies are rapidly advanced. However, the battery capacity has not experienced anequivalent increase. The user experience of modern mobile systems is therefore greatly affected by the battery lifetime,which is an unstable factor that is hard to control. To address this problem, previous works proposed energy-centric power management (PM) schemes to provide strong guarantee on the battery lifetime by globally managing energy as the first-class resource in the system. As the processor scheduler plays a pivotal role in power management and application performance guarantee, this thesis explores the user experience optimization of energy-limited mobile systemsfrom the perspective of energy-centric processor scheduling in an energy-centric context. This thesis first analyzes the general contributing factors of the mobile system user experience.Then itdetermines the essential requirements on the energy-centric processor scheduling for user experience optimization, which are proportional power sharing, time-constraint compliance, and when necessary, a tradeoff between the power share and the time-constraint compliance. To meet the requirements, the classical fair queuing algorithm and its reference model are extended from the network and CPU bandwidth sharing domain to the energy sharing domain, and based on that, the energy-based fair queuing (EFQ) algorithm is proposed for performing energy-centric processor scheduling. The EFQ algorithm is designed to provide proportional power shares to tasks by scheduling the tasks based on their energy consumption and weights. The power share of each time-sensitive task is protected upon the change of the scheduling environment to guarantee a stable performance, and any instantaneous power share that is overly allocated to one time-sensitive task can be fairly re-allocated to the other tasks. In addition, to better support real-time and multimedia scheduling, certain real-time friendly mechanism is combined into the EFQ algorithm to give time-limited scheduling preference to the time-sensitive tasks. Through high-level modelling and simulation, the properties of the EFQ algorithm are evaluated. The simulation results indicate that the essential requirements of energy-centric processor scheduling can be achieved. The EFQ algorithm is later implemented in the Linux kernel. To assess the properties of the Linux-based EFQ scheduler, an experimental test-bench based on an embedded platform, a multithreading test-bench program, and an open-source benchmark suite is developed. Through specifically-designed experiments, this thesis first verifies the properties of EFQ in power share management and real-time scheduling, and then, explores the potential benefits of employing EFQ scheduling in the user experience optimization for energy-limited mobile systems. Experimental results on power share management show that EFQ is more effective than the Linux-CFS scheduler in managing power shares and it can achieve a proportional sharing of the system power regardless of on which device the energy is spent. Experimental results on real-time scheduling demonstrate that EFQ can achieve effective, flexible and robust time-constraint compliance upon the increase of energy estimation error and task number. Finally, a comparative analysis of the experimental results on user experience optimization demonstrates that EFQ is more effective and flexible than traditional processor scheduling algorithms, such as those of the default Linux scheduler, in optimizing and preserving the user experience of energy-limited mobile systems.

Sistemas web con alta disponibilidad en cloud

Este trabajo contiene el estudio de las tecnologías que se están usando actualmente en web, tratando de explicar cuáles son sus principales componentes, su objetivo y funcionamiento. En base a un supuesto teórico de un montaje para un servicio web con un número muy alto de usuarios, y basándose en las tecnologías estudiadas, se propone un posible montaje completo de un sistema, que sería capaz de gestionar correctamente todas las peticiones, evitando fallos y tiempos de indisponibilidad. Se a~nade un análisis teórico de los costes deribados de la implantación del sistema, comparándolo con un sistema web convencional, y otro análisis con el funcionamiento de una caché y los benéficos, en carga, derivados de su uso.---ABSTRACT---This work contains a study about new web technologies. Its objective is to explain the web technologies componentes with their particular usage and performance. Based on a theorical postulation about a preparation of a web service with a large number of users, and working with the studied technologies, a complete system assembling is proposed. This system will be able to attend all the incoming requests, without failures nor downtimes. It is attached a theorical study of the derivative costs associated to the system implementation, compared to a traditional one. In addition, another study is included with the work ow of a cache and the benefits derived of its usage in work terms.

Towards cost reduction in concentrating solar power: innovative design for an efficient fresnel based solar field

Energía termosolar (de concentración) es uno de los nombres que hacen referencia en español al término inglés “concentrating solar power”. Se trata de una tecnología basada en la captura de la potencia térmica de la radiación solar, de forma que permita alcanzar temperaturas capaces de alimentar un ciclo termodinámico convencional (o avanzado); el futuro de esta tecnología depende principalmente de su capacidad para concentrar la radiación solar de manera eficiente y económica. La presente tesis está orientada hacia la resolución de ciertos problemas importantes relacionados con este objetivo. La mencionada necesidad de reducir costes en la concentración de radiación solar directa, asegurando el objetivo termodinámico de calentar un fluido hasta una determinada temperatura, es de vital importancia. Los colectores lineales Fresnel han sido identificados en la literatura científica como una tecnología con gran potencial para alcanzar esta reducción de costes. Dicha tecnología ha sido seleccionada por numerosas razones, entre las que destacan su gran libertad de diseño y su actual estado inmaduro. Con el objetivo de responder a este desafío se desarrollado un detallado estudio de las propiedades ópticas de los colectores lineales Fresnel, para lo cual se han utilizado métodos analíticos y numéricos de manera combinada. En primer lugar, se han usado unos modelos para la predicción de la localización y la irradiación normal directa del sol junto a unas relaciones analíticas desarrolladas para estudiar el efecto de múltiples variables de diseño en la energía incidente sobre los espejos. Del mismo modo, se han obtenido analíticamente los errores debidos al llamado “off-axis aberration”, a la apertura de los rayos reflejados en los espejos y a las sombras y bloqueos entre espejos. Esto ha permitido la comparación de diferentes formas de espejo –planos, circulares o parabólicos–, así como el diseño preliminar de la localización y anchura de los espejos y receptor sin necesidad de costosos métodos numéricos. En segundo lugar, se ha desarrollado un modelo de trazado de rayos de Monte Carlo con el objetivo de comprobar la validez del estudio analítico, pero sobre todo porque este no es preciso en el estudio de la reflexión en espejos. El código desarrollado está específicamente ideado para colectores lineales Fresnel, lo que ha permitido la reducción del tiempo de cálculo en varios órdenes de magnitud en comparación con un programa comercial más general. Esto justifica el desarrollo de un nuevo código en lugar de la compra de una licencia de otro programa. El modelo ha sido usado primeramente para comparar la intensidad de flujo térmico y rendimiento de colectores Fresnel, con y sin reflector secundario, con los colectores cilíndrico parabólicos. Finalmente, la conjunción de los resultados obtenidos en el estudio analítico con el programa numérico ha sido usada para optimizar el campo solar para diferentes orientaciones –Norte-Sur y Este-Oeste–, diferentes localizaciones –Almería y Aswan–, diferentes inclinaciones hacia el Trópico –desde 0 deg hasta 32 deg– y diferentes mínimos de intensidad del flujo en el centro del receptor –10 kW/m2 y 25 kW/m2–. La presente tesis ha conducido a importantes descubrimientos que deben ser considerados a la hora de diseñar un campo solar Fresnel. En primer lugar, los espejos utilizados no deben ser plano, sino cilíndricos o parabólicos, ya que los espejos curvos implican mayores concentraciones y rendimiento. Por otro lado, se ha llegado a la conclusión de que la orientación Este-Oeste es más propicia para localizaciones con altas latitudes, como Almería, mientras que en zonas más cercanas a los trópicos como Aswan los campos Norte-Sur conducen a mayores rendimientos. Es de destacar que la orientación Este-Oeste requiere aproximadamente la mitad de espejos que los campos Norte-Sur, puediendo estar inclinados hacia los Trópicos para mejorar el rendimiento, y que alcanzan parecidos valores de intensidad térmica en el receptor todos los días a mediodía. Sin embargo, los campos con orientación Norte-Sur permiten un flujo más constante a lo largo de un día. Por último, ha sido demostrado que el uso de diseños pre-optimizados analíticamente, con anchura de espejos y espaciado entre espejos variables a lo ancho del campo, pueden implicar aumentos de la energía generada por metro cuadrado de espejos de hasta el 6%. El rendimiento óptico anual de los colectores cilíndrico parabólicos es 23 % mayor que el rendimiento de los campos Fresnel en Almería, mientras que la diferencia es de solo 9 % en Aswan. Ello implica que, para alcanzar el mismo precio de electricidad que la tecnología de referencia, la reducción de costes de instalación por metro cuadrado de espejo debe estar entre el 10 % y el 25 %, y que los colectores lineales Fresnel tienen más posibilidades de ser desarrollados en zonas de bajas latitudes. Como consecuencia de los estudios desarrollados en esta tesis se ha patentado un sistema de almacenamiento que tiene en cuenta la variación del flujo térmico en el receptor a lo largo del día, especialmente para campos con orientación Este-Oeste. Este invento permitiría el aprovechamiento de la energía incidente durante más parte del año, aumentando de manera apreciable los rendimientos óptico y térmico. Abstract Concentrating solar power is the common name of a technology based on capturing the thermal power of solar radiation, in a suitable way to reach temperatures able to activate a conventional (or advanced) thermodynamic cycle to generate electricity; this quest mainly depends on our ability to concentrate solar radiation in a cheap and efficient way. The present thesis is focused to highlight and help solving some of the important issues related to this problem. The need of reducing costs in concentrating the direct solar radiation, but without jeopardizing the thermodynamic objective of heating a fluid up to the required temperature, is of prime importance. Linear Fresnel collectors have been identified in the scientific literature as a technology with high potential to reach this cost reduction. This technology has been selected because of a number of reasons, particularly the degrees of freedom of this type of concentrating configuration and its current immature state. In order to respond to this challenge, a very detailed exercise has been carried out on the optical properties of linear Fresnel collectors. This has been done combining analytic and numerical methods. First, the effect of the design variables on the ratio of energy impinging onto the reflecting surface has been studied using analytically developed equations, together with models that predict the location and direct normal irradiance of the sun at any moment. Similarly, errors due to off-axis aberration, to the aperture of the reflected energy beam and to shading and blocking effects have been obtained analytically. This has allowed the comparison of different shapes of mirrors –flat, cylindrical or parabolic–, as well as a preliminary optimization of the location and width of mirrors and receiver with no need of time-consuming numerical models. Second, in order to prove the validity of the analytic results, but also due to the fact that the study of the reflection process is not precise enough when using analytic equations, a Monte Carlo Ray Trace model has been developed. The developed code is designed specifically for linear Fresnel collectors, which has reduced the computing time by several orders of magnitude compared to a wider commercial software. This justifies the development of the new code. The model has been first used to compare radiation flux intensities and efficiencies of linear Fresnel collectors, both multitube receiver and secondary reflector receiver technologies, with parabolic trough collectors. Finally, the results obtained in the analytic study together with the numeric model have used in order to optimize the solar field for different orientations –North-South and East-West–, different locations –Almería and Aswan–, different tilts of the field towards the Tropic –from 0 deg to 32 deg– and different flux intensity minimum requirements –10 kW/m2 and 25 kW/m2. This thesis work has led to several important findings that should be considered in the design of Fresnel solar fields. First, flat mirrors should not be used in any case, as cylindrical and parabolic mirrors lead to higher flux intensities and efficiencies. Second, it has been concluded that, in locations relatively far from the Tropics such as Almería, East-West embodiments are more efficient, while in Aswan North- South orientation leads to a higher annual efficiency. It must be noted that East-West oriented solar fields require approximately half the number of mirrors than NS oriented fields, can be tilted towards the Equator in order to increase the efficiency and attain similar values of flux intensity at the receiver every day at midday. On the other hand, in NS embodiments the flux intensity is more even during each single day. Finally, it has been proved that the use of analytic designs with variable shift between mirrors and variable width of mirrors across the field can lead to improvements in the electricity generated per reflecting surface square meter up to 6%. The annual optical efficiency of parabolic troughs has been found to be 23% higher than the efficiency of Fresnel fields in Almería, but it is only around 9% higher in Aswan. This implies that, in order to attain the same levelized cost of electricity than parabolic troughs, the required reduction of installation costs per mirror square meter is in the range of 10-25%. Also, it is concluded that linear Fresnel collectors are more suitable for low latitude areas. As a consequence of the studies carried out in this thesis, an innovative storage system has been patented. This system takes into account the variation of the flux intensity along the day, especially for East-West oriented solar fields. As a result, the invention would allow to exploit the impinging radiation along longer time every day, increasing appreciably the optical and thermal efficiencies.

Methodology for developing and application outsourcing in the cloud using SOA

New technologies such as, the new Information and Communication Technology ICT, break new paths and redefines the way we understand business, the Cloud Computing is one of them. The on demand resource gathering and the per usage payment scheme are now commonplace, and allows companies to save on their ICT investments. Despite the importance of this issue, we still lack methodologies that help companies, to develop applications oriented for its exploitation in the Cloud. In this study we aim to fill this gap and propose a methodology for the development of ICT applications, which are directed towards a business model, and further outsourcing in the Cloud. In the former the Development of SOA applications, we take, as a baseline scenario, a business model from which to obtain a business process model. To this end, we use software engineering tools; and in the latter The Outsourcing we propose a guide that would facilitate uploading business models into the Cloud; to this end we describe a SOA governance model, which controls the SOA. Additionally we propose a Cloud government that integrates Service Level Agreements SLAs, plus SOA governance, and Cloud architecture. Finally we apply our methodology in an example illustrating our proposal. We believe that our proposal can be used as a guide/pattern for the development of business applications.

A novel energy-driven computing paradigm for e-health scenarios

A first-rate e-Health system saves lives, provides better patient care, allows complex but useful epidemiologic analysis and saves money. However, there may also be concerns about the costs and complexities associated with e-health implementation, and the need to solve issues about the energy footprint of the high-demanding computing facilities. This paper proposes a novel and evolved computing paradigm that: (i) provides the required computing and sensing resources; (ii) allows the population-wide diffusion; (iii) exploits the storage, communication and computing services provided by the Cloud; (iv) tackles the energy-optimization issue as a first-class requirement, taking it into account during the whole development cycle. The novel computing concept and the multi-layer top-down energy-optimization methodology obtain promising results in a realistic scenario for cardiovascular tracking and analysis, making the Home Assisted Living a reality.

Enhancing regression models for complex systems using evolutionary techniques for feature engineering

This work proposes an automatic methodology for modeling complex systems. Our methodology is based on the combination of Grammatical Evolution and classical regression to obtain an optimal set of features that take part of a linear and convex model. This technique provides both Feature Engineering and Symbolic Regression in order to infer accurate models with no effort or designer's expertise requirements. As advanced Cloud services are becoming mainstream, the contribution of data centers in the overall power consumption of modern cities is growing dramatically. These facilities consume from 10 to 100 times more power per square foot than typical office buildings. Modeling the power consumption for these infrastructures is crucial to anticipate the effects of aggressive optimization policies, but accurate and fast power modeling is a complex challenge for high-end servers not yet satisfied by analytical approaches. For this case study, our methodology minimizes error in power prediction. This work has been tested using real Cloud applications resulting on an average error in power estimation of 3.98%. Our work improves the possibilities of deriving Cloud energy efficient policies in Cloud data centers being applicable to other computing environments with similar characteristics.

Towards a unified sentiment lexicon based on graphics processing units

This paper presents an approach to create what we have called a Unified Sentiment Lexicon (USL). This approach aims at aligning, unifying, and expanding the set of sentiment lexicons which are available on the web in order to increase their robustness of coverage. One problem related to the task of the automatic unification of different scores of sentiment lexicons is that there are multiple lexical entries for which the classification of positive, negative, or neutral {P, Z, N} depends on the unit of measurement used in the annotation methodology of the source sentiment lexicon. Our USL approach computes the unified strength of polarity of each lexical entry based on the Pearson correlation coefficient which measures how correlated lexical entries are with a value between 1 and -1, where 1 indicates that the lexical entries are perfectly correlated, 0 indicates no correlation, and -1 means they are perfectly inversely correlated and so is the UnifiedMetrics procedure for CPU and GPU, respectively. Another problem is the high processing time required for computing all the lexical entries in the unification task. Thus, the USL approach computes a subset of lexical entries in each of the 1344 GPU cores and uses parallel processing in order to unify 155802 lexical entries. The results of the analysis conducted using the USL approach show that the USL has 95.430 lexical entries, out of which there are 35.201 considered to be positive, 22.029 negative, and 38.200 neutral. Finally, the runtime was 10 minutes for 95.430 lexical entries; this allows a reduction of the time computing for the UnifiedMetrics by 3 times.