Chapter 2 On the usage of the measurements of geographical concentration and specialization with areal data

Measures have been developed to understand tendencies in the distribution of economic activity. The merits of these measures are in the convenience of data collection and processing. In this interim report, investigating the property of such measures to determine the geographical spread of economic activities, we summarize the merits and limitations of measures, and make clear that we must apply caution in their usage. As a first trial to access areal data, this project focus on administrative areas, not on point data and input-output data. Firm level data is not within the scope of this article. The rest of this article is organized as follows. In Section 2, we touch on the the limitations and problems associated with the measures and areal data. Specific measures are introduced in Section 3, and applied in Section 4. The conclusion summarizes the findings and discusses future work.

Concurrency in prolog using threads and a shared database

Concurrency in Logic Programming has received much attention in the past. One problem with many proposals, when applied to Prolog, is that they involve large modifications to the standard implementations, and/or the communication and synchronization facilities provided do not fit as naturally within the language model as we feel is possible. In this paper we propose a new mechanism for implementing synchronization and communication for concurrency, based on atomic accesses to designated facts in the (shared) datábase. We argüe that this model is comparatively easy to implement and harmonizes better than previous proposals within the Prolog control model and standard set of built-ins. We show how in the proposed model it is easy to express classical concurrency algorithms and to subsume other mechanisms such as Linda, variable-based communication, or classical parallelism-oriented primitives. We also report on an implementation of the model and provide performance and resource consumption data.

Automatic unrestricted independent and-parallelism in logic programs

We present new algorithms which perform automatic parallelization via source-to-source transformations. The objective is to exploit goal-level, unrestricted independent andparallelism. The proposed algorithms use as targets new parallel execution primitives which are simpler and more flexible than the well-known &/2 parallel operator, which makes it possible to generate better parallel expressions by exposing more potential parallelism among the literals of a clause than is possible with &/2. The main differences between the algorithms stem from whether the order of the solutions obtained is preserved or not, and on the use of determinacy information. We briefly describe the environment where the algorithms have been implemented and the runtime platform in which the parallelized programs are executed. We also report on an evaluation of an implementation of our approach. We compare the performance obtained to that of previous annotation algorithms and show that relevant improvements can be obtained.

Código híbrido avanzado de motores de plasma de efecto Hall

La propulsión eléctrica constituye hoy una tecnología muy competitiva y de gran proyección de futuro. Dentro de los diversos motores de plasma existentes, el motor de efecto Hall ha adquirido una gran madurez y constituye un medio de propulsión idóneo para un rango amplio de misiones. En la presente Tesis se estudian los motores Hall con geometría convencional y paredes dieléctricas. La compleja interacción entre los múltiples fenómenos físicos presentes hace que sea difícil la simulación del plasma en estos motores. Los modelos híbridos son los que representan un mejor compromiso entre precisión y tiempo de cálculo. Se basan en utilizar un modelo fluido para los electrones y algoritmos de dinámica de partículas PIC (Particle-In- Cell) para los iones y los neutros. Permiten hacer uso de la hipótesis de cuasineutralidad del plasma, a cambio de resolver separadamente las capas límite (o vainas) que se forman en torno a las paredes de la cámara. Partiendo de un código híbrido existente, llamado HPHall-2, el objetivo de la Tesis doctoral ha sido el desarrollo de un código híbrido avanzado que mejorara la simulación de la descarga de plasma en un motor de efecto Hall. Las actualizaciones y mejoras realizadas en las diferentes partes que componen el código comprenden tanto aspectos teóricos como numéricos. Fruto de la extensa revisión de la algoritmia del código HPHall-2 se han conseguido reducir los errores de precisión un orden de magnitud, y se ha incrementado notablemente su consistencia y robustez, permitiendo la simulación del motor en un amplio rango de condiciones. Algunos aspectos relevantes a destacar en el subcódigo de partículas son: la implementación de un nuevo algoritmo de pesado que permite determinar de forma más precisa el flujo de las magnitudes del plasma; la implementación de un nuevo algoritmo de control de población, que permite tener suficiente número de partículas cerca de las paredes de la cámara, donde los gradientes son mayores y las condiciones de cálculo son más críticas; las mejoras en los balances de masa y energía; y un mejor cálculo del campo eléctrico en una malla no uniforme. Merece especial atención el cumplimiento de la condición de Bohm en el borde de vaina, que en los códigos híbridos representa una condición de contorno necesaria para obtener una solución consistente con el modelo de interacción plasma-pared, y que en HPHall-2 aún no se había resuelto satisfactoriamente. En esta Tesis se ha implementado el criterio cinético de Bohm para una población de iones con diferentes cargas eléctricas y una gran dispersión de velocidades. En el código, el cumplimiento de la condición cinética de Bohm se consigue por medio de un algoritmo que introduce una fina capa de aceleración nocolisional adyacente a la vaina y mide adecuadamente el flujo de partículas en el espacio y en el tiempo. Las mejoras realizadas en el subcódigo de electrones incrementan la capacidad de simulación del código, especialmente en la región aguas abajo del motor, donde se simula la neutralización del chorro del plasma por medio de un modelo de cátodo volumétrico. Sin abordar el estudio detallado de la turbulencia del plasma, se implementan modelos sencillos de ajuste de la difusión anómala de Bohm, que permiten reproducir los valores experimentales del potencial y la temperatura del plasma, así como la corriente de descarga del motor. En cuanto a los aspectos teóricos, se hace especial énfasis en la interacción plasma-pared y en la dinámica de los electrones secundarios libres en el interior del plasma, cuestiones que representan hoy en día problemas abiertos en la simulación de los motores Hall. Los nuevos modelos desarrollados buscan una imagen más fiel a la realidad. Así, se implementa el modelo de vaina de termalización parcial, que considera una función de distribución no-Maxwelliana para los electrones primarios y contabiliza unas pérdidas energéticas más cercanas a la realidad. Respecto a los electrones secundarios, se realiza un estudio cinético simplificado para evaluar su grado de confinamiento en el plasma, y mediante un modelo fluido en el límite no-colisional, se determinan las densidades y energías de los electrones secundarios libres, así como su posible efecto en la ionización. El resultado obtenido muestra que los electrones secundarios se pierden en las paredes rápidamente, por lo que su efecto en el plasma es despreciable, no así en las vainas, donde determinan el salto de potencial. Por último, el trabajo teórico y de simulación numérica se complementa con el trabajo experimental realizado en el Pnnceton Plasma Physics Laboratory, en el que se analiza el interesante transitorio inicial que experimenta el motor en el proceso de arranque. Del estudio se extrae que la presencia de gases residuales adheridos a las paredes juegan un papel relevante, y se recomienda, en general, la purga completa del motor antes del modo normal de operación. El resultado final de la investigación muestra que el código híbrido desarrollado representa una buena herramienta de simulación de un motor Hall. Reproduce adecuadamente la física del motor, proporcionando resultados similares a los experimentales, y demuestra ser un buen laboratorio numérico para estudiar el plasma en el interior del motor. Abstract Electric propulsion is today a very competitive technology and has a great projection into the future. Among the various existing plasma thrusters, the Hall effect thruster has acquired a considerable maturity and constitutes an ideal means of propulsion for a wide range of missions. In the present Thesis only Hall thrusters with conventional geometry and dielectric walls are studied. The complex interaction between multiple physical phenomena makes difficult the plasma simulation in these engines. Hybrid models are those representing a better compromise between precision and computational cost. They use a fluid model for electrons and Particle-In-Cell (PIC) algorithms for ions and neutrals. The hypothesis of plasma quasineutrality is invoked, which requires to solve separately the sheaths formed around the chamber walls. On the basis of an existing hybrid code, called HPHall-2, the aim of this doctoral Thesis is to develop an advanced hybrid code that better simulates the plasma discharge in a Hall effect thruster. Updates and improvements of the code include both theoretical and numerical issues. The extensive revision of the algorithms has succeeded in reducing the accuracy errors in one order of magnitude, and the consistency and robustness of the code have been notably increased, allowing the simulation of the thruster in a wide range of conditions. The most relevant achievements related to the particle subcode are: the implementation of a new weighing algorithm that determines more accurately the plasma flux magnitudes; the implementation of a new algorithm to control the particle population, assuring enough number of particles near the chamber walls, where there are strong gradients and the conditions to perform good computations are more critical; improvements in the mass and energy balances; and a new algorithm to compute the electric field in a non-uniform mesh. It deserves special attention the fulfilment of the Bohm condition at the edge of the sheath, which represents a boundary condition necessary to match consistently the hybrid code solution with the plasma-wall interaction, and remained as a question unsatisfactory solved in the HPHall-2 code. In this Thesis, the kinetic Bohm criterion has been implemented for an ion particle population with different electric charges and a large dispersion in their velocities. In the code, the fulfilment of the kinetic Bohm condition is accomplished by an algorithm that introduces a thin non-collisional layer next to the sheaths, producing the ion acceleration, and measures properly the flux of particles in time and space. The improvements made in the electron subcode increase the code simulation capabilities, specially in the region downstream of the thruster, where the neutralization of the plasma jet is simulated using a volumetric cathode model. Without addressing the detailed study of the plasma turbulence, simple models for a parametric adjustment of the anomalous Bohm difussion are implemented in the code. They allow to reproduce the experimental values of the plasma potential and the electron temperature, as well as the discharge current of the thruster. Regarding the theoretical issues, special emphasis has been made in the plasma-wall interaction of the thruster and in the dynamics of free secondary electrons within the plasma, questions that still remain unsolved in the simulation of Hall thrusters. The new developed models look for results closer to reality, such as the partial thermalization sheath model, that assumes a non-Maxwellian distribution functions for primary electrons, and better computes the energy losses at the walls. The evaluation of secondary electrons confinement within the chamber is addressed by a simplified kinetic study; and using a collisionless fluid model, the densities and energies of free secondary electrons are computed, as well as their effect on the plasma ionization. Simulations show that secondary electrons are quickly lost at walls, with a negligible effect in the bulk of the plasma, but they determine the potential fall at sheaths. Finally, numerical simulation and theoretical work is complemented by the experimental work carried out at the Princeton Plasma Physics Laboratory, devoted to analyze the interesting transitional regime experienced by the thruster in the startup process. It is concluded that the gas impurities adhered to the thruster walls play a relevant role in the transitional regime and, as a general recomendation, a complete purge of the thruster before starting its normal mode of operation it is suggested. The final result of the research conducted in this Thesis shows that the developed code represents a good tool for the simulation of Hall thrusters. The code reproduces properly the physics of the thruster, with results similar to the experimental ones, and represents a good numerical laboratory to study the plasma inside the thruster.

Adapting autonomously classification data mining algorithms for ubiquitous devices

Abstract Due to recent scientific and technological advances in information sys¬tems, it is now possible to perform almost every application on a mobile device. The need to make sense of such devices more intelligent opens an opportunity to design data mining algorithm that are able to autonomous execute in local devices to provide the device with knowledge. The problem behind autonomous mining deals with the proper configuration of the algorithm to produce the most appropriate results. Contextual information together with resource information of the device have a strong impact on both the feasibility of a particu¬lar execution and on the production of the proper patterns. On the other hand, performance of the algorithm expressed in terms of efficacy and efficiency highly depends on the features of the dataset to be analyzed together with values of the parameters of a particular implementation of an algorithm. However, few existing approaches deal with autonomous configuration of data mining algorithms and in any case they do not deal with contextual or resources information. Both issues are of particular significance, in particular for social net¬works application. In fact, the widespread use of social networks and consequently the amount of information shared have made the need of modeling context in social application a priority. Also the resource consumption has a crucial role in such platforms as the users are using social networks mainly on their mobile devices. This PhD thesis addresses the aforementioned open issues, focusing on i) Analyzing the behavior of algorithms, ii) mapping contextual and resources information to find the most appropriate configuration iii) applying the model for the case of a social recommender. Four main contributions are presented: - The EE-Model: is able to predict the behavior of a data mining algorithm in terms of resource consumed and accuracy of the mining model it will obtain. - The SC-Mapper: maps a situation defined by the context and resource state to a data mining configuration. - SOMAR: is a social activity (event and informal ongoings) recommender for mobile devices. - D-SOMAR: is an evolution of SOMAR which incorporates the configurator in order to provide updated recommendations. Finally, the experimental validation of the proposed contributions using synthetic and real datasets allows us to achieve the objectives and answer the research questions proposed for this dissertation.

Diseño, optimización y análisis de sistemas basados en técnicas láser, para el modelado geométrico, registro y documentación, aplicados a entidades de interés patrimonial.

El objetivo de la presente tesis doctoral es el desarrollo e implementación de un sistema para mejorar la metodología de extracción de la información geométrica necesaria asociada a los procesos de documentación de entidades de interés patrimonial, a partir de la información proporcionada por el empleo de sensores láser, tanto aéreos como terrestres. Para ello, inicialmente se realiza una presentación y justificación de los antecedentes y la problemática en el registro de información geométrica para el patrimonio, detallando todos aquellos sistemas de registro y análisis de la información geométrica utilizados en la actualidad. Este análisis permitirá realizar la comparación con los sistemas de registro basados en técnicas láser, aportando sugerencias de utilización para cada caso concreto. Posteriormente, se detallan los sistemas de registro basados en técnicas láser, comenzando por los sensores aerotransportados y concluyendo con el análisis pormenorizado de los sensores terrestres, tanto en su aplicación en modo estático como móvil. Se exponen las características técnicas y funcionamiento de cada uno de ellos, así como los ámbitos de aplicación y productos generados. Se analizan las fuentes de error que determinan la precisión que puede alcanzar el sistema. Tras la exposición de las características de los sistemas LiDAR, se detallan los procesos a realizar con los datos extraídos para poder generar la información necesaria para los diferentes tipos de objetos analizados. En esta exposición, se hace hincapié en los posibles riesgos que pueden ocurrir en algunas fases delicadas y se analizarán los diferentes algoritmos de filtrado y clasificación de los puntos, fundamentales en el procesamiento de la información LiDAR. Seguidamente, se propone una alternativa para optimizar los modelos de procesamiento existentes, basándose en el desarrollo de algoritmos nuevos y herramientas informáticas que mejoran el rendimiento en la gestión de la información LiDAR. En la implementación, se han tenido en cuenta características y necesidades particulares de la documentación de entidades de interés patrimonial, así como los diferentes ámbitos de utilización del LiDAR, tanto aéreo como terrestre. El resultado es un organigrama de las tareas a realizar desde la nube de puntos LiDAR hasta el cálculo de los modelos digitales del terreno y de superficies. Para llevar a cabo esta propuesta, se han desarrollado hasta 19 algoritmos diferentes que comprenden implementaciones para el modelado en 2.5D y 3D, visualización, edición, filtrado y clasificación de datos LiDAR, incorporación de información de sensores pasivos y cálculo de mapas derivados, tanto raster como vectoriales, como pueden ser mapas de curvas de nivel y ortofotos. Finalmente, para dar validez y consistencia a los desarrollos propuestos, se han realizado ensayos en diferentes escenarios posibles en un proceso de documentación del patrimonio y que abarcan desde proyectos con sensores aerotransportados, proyectos con sensores terrestres estáticos a media y corta distancia, así como un proyecto con un sensor terrestre móvil. Estos ensayos han permitido definir los diferentes parámetros necesarios para el adecuado funcionamiento de los algoritmos propuestos. Asimismo, se han realizado pruebas objetivas expuestas por la ISPRS para la evaluación y comparación del funcionamiento de algoritmos de clasificación LiDAR. Estas pruebas han permitido extraer datos de rendimiento y efectividad del algoritmo de clasificación presentado, permitiendo su comparación con otros algoritmos de prestigio existentes. Los resultados obtenidos han constatado el funcionamiento satisfactorio de la herramienta. Esta tesis está enmarcada dentro del proyecto Consolider-Ingenio 2010: “Programa de investigación en tecnologías para la valoración y conservación del patrimonio cultural” (ref. CSD2007-00058) realizado por el Consejo Superior de Investigaciones Científicas y la Universidad Politécnica de Madrid. ABSTRACT: The goal of this thesis is the design, development and implementation of a system to improve the extraction of useful geometric information in Heritage documentation processes. This system is based on information provided by laser sensors, both aerial and terrestrial. Firstly, a presentation of recording geometric information for Heritage processes is done. Then, a justification of the background and problems is done too. Here, current systems for recording and analyzing the geometric information are studied. This analysis will perform the comparison with the laser system techniques, providing suggestions of use for each specific case. Next, recording systems based on laser techniques are detailed. This study starts with airborne sensors and ends with terrestrial ones, both in static and mobile application. The technical characteristics and operation of each of them are described, as well as the areas of application and generated products. Error sources are also analyzed in order to know the precision this technology can achieve. Following the presentation of the LiDAR system characteristics, the processes to generate the required information for different types of scanned objects are described; the emphasis is on the potential risks that some steps can produce. Moreover different filtering and classification algorithms are analyzed, because of their main role in LiDAR processing. Then, an alternative to optimize existing processing models is proposed. It is based on the development of new algorithms and tools that improve the performance in LiDAR data management. In this implementation, characteristics and needs of the documentation of Heritage entities have been taken into account. Besides, different areas of use of LiDAR are considered, both air and terrestrial. The result is a flowchart of tasks from the LiDAR point cloud to the calculation of digital terrain models and digital surface models. Up to 19 different algorithms have been developed to implement this proposal. These algorithms include implementations for 2.5D and 3D modeling, viewing, editing, filtering and classification of LiDAR data, incorporating information from passive sensors and calculation of derived maps, both raster and vector, such as contour maps and orthophotos. Finally, in order to validate and give consistency to the proposed developments, tests in different cases have been executed. These tests have been selected to cover different possible scenarios in the Heritage documentation process. They include from projects with airborne sensors, static terrestrial sensors (medium and short distances) to mobile terrestrial sensor projects. These tests have helped to define the different parameters necessary for the appropriate functioning of the proposed algorithms. Furthermore, proposed tests from ISPRS have been tested. These tests have allowed evaluating the LiDAR classification algorithm performance and comparing it to others. Therefore, they have made feasible to obtain performance data and effectiveness of the developed classification algorithm. The results have confirmed the reliability of the tool. This investigation is framed within Consolider-Ingenio 2010 project titled “Programa de investigación en tecnologías para la valoración y conservación del patrimonio cultural” (ref. CSD2007-00058) by Consejo Superior de Investigaciones Científicas and Universidad Politécnica de Madrid.

Performance of artificial neural networks and genetical evolved artificial neural networks unfolding techniques

With the Bonner spheres spectrometer neutron spectrum is obtained through an unfolding procedure. Monte Carlo methods, Regularization, Parametrization, Least-squares, and Maximum Entropy are some of the techniques utilized for unfolding. In the last decade methods based on Artificial Intelligence Technology have been used. Approaches based on Genetic Algorithms and Artificial Neural Networks have been developed in order to overcome the drawbacks of previous techniques. Nevertheless the advantages of Artificial Neural Networks still it has some drawbacks mainly in the design process of the network, vg the optimum selection of the architectural and learning ANN parameters. In recent years the use of hybrid technologies, combining Artificial Neural Networks and Genetic Algorithms, has been utilized to. In this work, several ANN topologies were trained and tested using Artificial Neural Networks and Genetically Evolved Artificial Neural Networks in the aim to unfold neutron spectra using the count rates of a Bonner sphere spectrometer. Here, a comparative study of both procedures has been carried out.

Effectiveness of combined sharing and freeness analysis using abstract interpretation

This paper presents improved unification algorithms, an implementation, and an analysis of the effectiveness of an abstract interpreter based on the sharing + freeness domain presented in a previous paper, which was designed to accurately and concisely represent combined freeness and sharing information for program variables. We first briefly review this domain and the unification algorithms previously proposed. We then improve these algorithms and correct them to deal with some cases which were not well analyzed previously, illustrating the improvement with an example. We then present the implementation of the improved algorithm and evaluate its performance by comparing the effectiveness of the information inferred to that of other interpreters available to us for an application (program parallelization) that is common to all these interpreters. All these systems have been embedded in a real parallelizing compiler. Effectiveness of the analysis is measured in terms of actual final performance of the system: i.e. in terms of the actual speedups obtained. The results show good performance for the combined domain in that it improves the accuracy of both types of information and also in that the analyzer using the combined domain is more effective in the application than any of the other analyzers it is compared to.

A review on probabilistic graphical models in evolutionary computation

Thanks to their inherent properties, probabilistic graphical models are one of the prime candidates for machine learning and decision making tasks especially in uncertain domains. Their capabilities, like representation, inference and learning, if used effectively, can greatly help to build intelligent systems that are able to act accordingly in different problem domains. Evolutionary algorithms is one such discipline that has employed probabilistic graphical models to improve the search for optimal solutions in complex problems. This paper shows how probabilistic graphical models have been used in evolutionary algorithms to improve their performance in solving complex problems. Specifically, we give a survey of probabilistic model building-based evolutionary algorithms, called estimation of distribution algorithms, and compare different methods for probabilistic modeling in these algorithms.

On a mathematical model arising in MHD perturbed equilibrium for Stellarator devices. A numerical approach.

Abstract?We consider a mathematical model related to the stationary regime of a plasma of fusion nuclear, magnetically confined in a Stellarator device. Using the geometric properties of the fusion device, a suitable system of coordinates and averaging methods, the mathematical problem may be reduced to a two dimensional free boundary problem of nonlocal type, where the corresponding differential equation is of the Grad?Shafranov type. The current balance within each flux magnetic gives us the possibility to define the third covariant magnetic field component with respect to the averaged poloidal flux function. We present here some numerical experiences and we give some numerical approach for the averaged poloidal flux and for the third covariant magnetic field component.

A hierarchical strategy for real-time tracking on-board UAVs

In this paper, we present a real-time tracking strategy based on direct methods for tracking tasks on-board UAVs, that is able to overcome problems posed by the challenging conditions of the task: e.g. constant vibrations, fast 3D changes, and limited capacity on-board. The vast majority of approaches make use of feature-based methods to track objects. Nonetheless, in this paper we show that although some of these feature-based solutions are faster, direct methods can be more robust under fast 3D motions (fast changes in position), some changes in appearance, constant vibrations (without requiring any specific hardware or software for video stabilization), and situations where part of the object to track is out the field of view of the camera. The performance of the proposed strategy is evaluated with images from real-flight tests using different evaluation mechanisms (e.g. accurate position estimation using a Vicon sytem). Results show that our tracking strategy performs better than well known feature-based algorithms and well known configurations of direct methods, and that the recovered data is robust enough for vision-in-the-loop tasks.

AUTOFLY-Aid: Flight Deck Automation Support with Dynamic 4D Trajectory Management for Responsive and Adaptive Airborne Collision Avoidance

AUTOFLY-Aid Project aims to develop and demonstrate novel automation support algorithms and tools to the flight crew for flight critical collision avoidance using “dynamic 4D trajectory management”. The automation support system is envisioned to improve the primary shortcomings of TCAS, and to aid the pilot through add-on avionics/head-up displays and reality augmentation devices in dynamically evolving collision avoidance scenarios. The main theoretical innovative and novel concepts to be developed by AUTOFLY-Aid project are a) design and development of the mathematical models of the full composite airspace picture from the flight deck’s perspective, as seen/measured/informed by the aircraft flying in SESAR 2020, b) design and development of a dynamic trajectory planning algorithm that can generate at real-time (on the order of seconds) flyable (i.e. dynamically and performance-wise feasible) alternative trajectories across the evolving stochastic composite airspace picture (which includes new conflicts, blunder risks, terrain and weather limitations) and c) development and testing of the Collision Avoidance Automation Support System on a Boeing 737 NG FNPT II Flight Simulator with synthetic vision and reality augmentation while providing the flight crew with quantified and visual understanding of collision risks in terms of time and directions and countermeasures.

Implementación de algoritmos para la manipulación de curvas concoides en diseño geométrico

Este proyecto se enmarca dentro de la Computación Simbólica y de los fundamentos matemáticos del Diseño Geométrico Asistido por ordenador (CAGD). Se abordara uno de los problemas principales en el ámbito del CAGD y que es la manipulación de las Curvas Concoide. La importancia del avance en la manipulación de las curvas concoide radica en el papel fundamental que desempeñan en múltiples aplicaciones en la actualidad dentro de campos de diversa índole tales como la medicina, la óptica, el electromagnetismo, la construcción, etc. El objetivo principal de este proyecto es el diseño e implementación de algoritmos para el estudio, cálculo y manipulación de curvas concoides, utilizando técnicas propias del Calculo Simbólico. Esta implementación se ha programado utilizando el sistema de computación simbólica Maple. El proyecto consiste en dos partes bien diferenciadas, una parte teórica y otra más practica. La primera incluye la descripción geométrica y definición formal de curvas concoide, así como las ideas y propiedades básicas. De forma más precisa, se presenta un estudio matemático sobre el análisis de racionalidad de estas curvas, explicando los algoritmos que serán implementados en las segunda parte, y que constituye el objetivo principal de este proyecto. Para cerrar esta parte, se presenta una pequeña introducción al sistema y a la programación en Maple. Por otro lado, la segunda parte de este proyecto es totalmente original, y en ella el autor desarrolla las implementaciones en Maple de los algoritmos presentados en la parte anterior, así como la creación de un paquete Maple que las recoge. Por último, se crean las paginas de ayudas en el sistema Maple para la correcta utilización del paquete matemático anteriormente mencionado. Una vez terminada la parte de implementación, se aplican los algoritmos implementados a una colección de curvas clásicas conocidas, recogiendo los datos y resultados obtenidos en un atlas de curvas. Finalmente, se presenta una recopilación de las aplicaciones más destacadas en las que las concoides desempeñan un papel importante así como una breve reseña sobre las concoides de superficies, objeto de varios estudios en la actualidad y a los que se considera que el presente proyecto les puede resultar de gran utilidad. Abstract This project is set up in the framework of Symbolic Computation as well as in the implementation of algebraic-geometric problems that arise from Computer Aided Geometric Design (C.A.G.D.) applications. We address problems related to conchoid curves. The importance of these curves is the fundamental role that they play in current applications as medicine, optics, electromagnetism, construction, etc. The main goal of this project is to design and implement some algorithms to solve problems in studying, calculating and generating conchoid curves with symbolic computation techniques. For this purpose, we program our implementations in the symbolic system “Maple". The project consists of two differentiated parts, one more theoretical part and another part more practical. The first one includes the description of conchoid curves as well as the basic ideas about the concept and its basic properties. More precisely, we introduce in this part the mathematical analysis of the rationality of the conchoids, and we present the algorithms that will be implemented. Furthermore, the reader will be brie y introduced in Maple programming. On the other hand, the second part of this project is totally original. In this more practical part, the author presents the implemented algorithms and a Maple package that includes them, as well as their help pages. These implemented procedures will be check and illustrated with some classical and well known curves, collecting the main properties of the conchoid curves obtained in a brief atlas. Finally, a compilation of the most important applications where conchoids play a fundamental role, and a brief introduction to the conchoids of surfaces, subject of several studies today and where this project could be very useful, are presented.

Contribution to flexible service coordination in mobile prosumer environments

Este trabajo de Tesis se desarrolla en el marco de los escenarios de ejecución distribuida de servicios móviles y contribuye a la definición y desarrollo del concepto de usuario prosumer. El usuario prosumer se caracteriza por utilizar su teléfono móvil para crear, proveer y ejecutar servicios. Este nuevo modelo de usuario contribuye al avance de la sociedad de la información, ya que el usuario prosumer se transforma de creador de contenidos a creador de servicios (estos últimos formados por contenidos y la lógica para acceder a ellos, procesarlos y representarlos). El objetivo general de este trabajo de Tesis es la provisión de un modelo de creación, distribución y ejecución de servicios para entorno móvil que permita a los usuarios no programadores (usuarios prosumer), pero expertos en un determinado dominio, crear y ejecutar sus propias aplicaciones y servicios. Para ello se definen, desarrollan e implementan metodologías, procesos, algoritmos y mecanismos adaptables a dominios específicos, para construir entornos de ejecución distribuida de servicios móviles para usuarios prosumer. La provisión de herramientas de creación adaptadas a usuarios no expertos es una tendencia actual que está siendo desarrollada en distintos trabajos de investigación. Sin embargo, no se ha propuesto una metodología de desarrollo de servicios que involucre al usuario prosumer en el proceso de diseño, desarrollo, implementación y validación de servicios. Este trabajo de Tesis realiza un estudio de las metodologías y tecnologías más innovadoras relacionadas con la co‐creación y utiliza este análisis para definir y validar una metodología que habilita al usuario para ser el responsable de la creación de servicios finales. Siendo los entornos móviles prosumer (mobile prosumer environments) una particularización de los entornos de ejecución distribuida de servicios móviles, en este trabajo se tesis se investiga en técnicas de adaptación, distribución, coordinación de servicios y acceso a recursos identificando como requisitos las problemáticas de este tipo de entornos y las características de los usuarios que participan en los mismos. Se contribuye a la adaptación de servicios definiendo un modelo de variabilidad que soporte la interdependencia entre las decisiones de personalización de los usuarios, incorporando mecanismos de guiado y detección de errores. La distribución de servicios se implementa utilizando técnicas de descomposición en árbol SPQR, cuantificando el impacto de separar cualquier servicio en distintos dominios. Considerando el plano de comunicaciones para la coordinación en la ejecución de servicios distribuidos hemos identificado varias problemáticas, como las pérdidas de enlace, conexiones, desconexiones y descubrimiento de participantes, que resolvemos utilizando técnicas de diseminación basadas en publicación subscripción y algoritmos Gossip. Para lograr una ejecución flexible de servicios distribuidos en entorno móvil, soportamos la adaptación a cambios en la disponibilidad de los recursos, proporcionando una infraestructura de comunicaciones para el acceso uniforme y eficiente a recursos. Se han realizado validaciones experimentales para evaluar la viabilidad de las soluciones propuestas, definiendo escenarios de aplicación relevantes (el nuevo universo inteligente, prosumerización de servicios en entornos hospitalarios y emergencias en la web de la cosas). Abstract This Thesis work is developed in the framework of distributed execution of mobile services and contributes to the definition and development of the concept of prosumer user. The prosumer user is characterized by using his mobile phone to create, provide and execute services. This new user model contributes to the advancement of the information society, as the prosumer is transformed from producer of content, to producer of services (consisting of content and logic to access them, process them and represent them). The overall goal of this Thesis work is to provide a model for creation, distribution and execution of services for the mobile environment that enables non‐programmers (prosumer users), but experts in a given domain, to create and execute their own applications and services. For this purpose I define, develop and implement methodologies, processes, algorithms and mechanisms, adapted to specific domains, to build distributed environments for the execution of mobile services for prosumer users. The provision of creation tools adapted to non‐expert users is a current trend that is being developed in different research works. However, it has not been proposed a service development methodology involving the prosumer user in the process of design, development, implementation and validation of services. This thesis work studies innovative methodologies and technologies related to the co‐creation and relies on this analysis to define and validate a methodological approach that enables the user to be responsible for creating final services. Being mobile prosumer environments a specific case of environments for distributed execution of mobile services, this Thesis work researches in service adaptation, distribution, coordination and resource access techniques, and identifies as requirements the challenges of such environments and characteristics of the participating users. I contribute to service adaptation by defining a variability model that supports the dependency of user personalization decisions, incorporating guiding and error detection mechanisms. Service distribution is implemented by using decomposition techniques based on SPQR trees, quantifying the impact of separating any service in different domains. Considering the communication level for the coordination of distributed service executions I have identified several problems, such as link losses, connections, disconnections and discovery of participants, which I solve using dissemination techniques based on publish‐subscribe communication models and Gossip algorithms. To achieve a flexible distributed service execution in mobile environments, I support adaptation to changes in the availability of resources, while providing a communication infrastructure for the uniform and efficient access to resources. Experimental validations have been conducted to assess the feasibility of the proposed solutions, defining relevant application scenarios (the new intelligent universe, service prosumerization in hospitals and emergency situations in the web of things).