La tesis se inscribe en un doble ámbito científico formado por la Estadística y la Pedagogía. El objetivo de la tesis es la investigación de modelos estadísticos y estrategias de análisis que puedan ser de utilidad en el seguimiento de sistemas de evaluación complejos. Su motivación se encuentra en la necesidad de analizar las Pruebas de Aptitud para el Acceso a la Universidad (PAAU), que regulan el acceso a la universidad en España, desde la perspectiva de la ciencia estadística. La validez y fiabilidad de los exámenes COU (Curso de Orientación Universitaria) y PAAU han merecido una atención especial a lo largo de la investigación. Asimismo, se analizan con detenimiento las principales fuentes de variación de dichas notas: las diferencias entre centros de secundaria y el proceso de corrección de las pruebas PAAU.En la Introducción, una vez resumidas las características del sistema de evaluación de las pruebas PAAU y discutido el papel de la estadística en el tratamiento de datos en educación, se establecen los objetivos concretos de la tesis, a la luz de las necesidades existentes y de los trabajos de investigación realizados hasta el momento.El Capítulo 1 ilustra las diferencias entre los exámenes COU y las pruebas PAAU. Se aborda el estudio de la asociación entre ambas puntuaciones. La modelización de la variación de la nota PAAU individual por medio de modelos de regresión coeficientes aleatorios permite evidenciar (y medir) las diferencias entre centros de secundaria en cuanto a los estándares utilizados en COU. Este primer capítulo contiene una detallada introducción a los modelos de coeficientes aleatorios, también llamados modelos de nivel múltiple, que posteriormente se aplicaran en los capítulos 2 y 4, en la versión de modelos multivariantes de componentes de la varianza. El segundo capitulo, en un enfoque que complementa el anterior, se centra en el estudio de las medias (de COU y de PAAU) de cada centro, en la estructura de covarianza entre ambas. Como resultado relevante cabe citar la aplicación a la selección de la combinación más eficiente. El Capítulo 3 se ha dedicado enteramente a la calidad del sistema de corrección de los exámenes PAAU. La modelización presentada ha permitido evaluar el impacto de los correctores en términos de la varianza debida a las diferencias en el grado de severidad y a la varianza generada por la inconsistencia. Para la obtención de los datos se ha requerido del diseño de experimentos. Dichos experimentos, que han evidenciado una serie de puntos débiles del sistema, deberían ser realizados de manera sistemática cada año en una estrategia de mejora de la calidad del proceso. El Capítulo 4 estudia la covarianza del conjunto de notas PAAU tanto a nivel estudiante como a nivel centro, ofreciendo nuevos elementos de reflexión para la validez de dichas pruebas. El Capítulo 5 resume la aplicación de varias propuestas de la tesis a la primera convocatoria de las pruebas PAAU-LOGSE. El Capítulo 6 incluye las conclusiones de la tesis así como una serie de propuestas de seguimiento y mejora de la calidad global del sistema.

Les systèmes logiciels s'orientent vers des environnements de plus en plus hétérogènes et dynamiques. Cette évolution est induite par différents facteurs : explosion des dispositifs embarqués avec de fortes capacités de calcul, adoption rapide des services distants fournis par des tiers, mobilité des usagers et évolution du contexte associé, etc. Ces facteurs ouvrent de grandes possibilités pour la construction de nouveaux services numériques dans des domaines aussi divers que la santé, le divertissement, la domotique, ou encore le transport. Ces nouveaux domaines d'applications demandent la mise en œuvre des opérations d'intégration dans des contextes dynamiques et hétérogènes. Il est aujourd'hui admis que les approches à services facilitent l'intégration logicielle par la définition de protocoles standard de découverte et de liaison. La problématique d'intégration, au sens médiation, reste néanmoins entière. Le problème principal abordé par cette thèse est l'intégration de services dans des contextes hétérogènes et dynamiques. Plus précisément, nous avons conçu un modèle à composant spécifique à l'intégration logicielle, nommé CILIA. Ce modèle repose sur des composants, appelés médiateurs, et sur un langage d'assemblage de ces médiateurs. CILIA reprend les grands principes du Génie Logiciel tels que l'abstraction, la séparation de préoccupations et la modularité, et s'appuie sur des patrons d'intégration bien connus (Enterprise Integration Patterns). CILIA est implanté sous la forme d'un framework dynamique qui permet la mise à jour à l'exécution des solutions d'intégration. Ce framework CILIA est pleinement opérationnel et disponible en open source. Il est utilisé dans plusieurs projets collaboratifs. / Software systems are moving toward highly dynamic and heterogeneous environments. This dynamism is derived by several factors: the massive arrival of embedded devices with computing capabilities, the rapid adoption of newer distributed services provided by third parties, the user mobility and the constantly changing context, etc. These factors open up great opportunities for the construction of new and innovative services on several application domains, such as health-care systems, entertainment systems, home automation systems, transportation or traceability systems. These new application areas require the implementation of integration operations in dynamic and heterogeneous environments. It is well known that service-oriented computing eases the implementation of integrating systems by defining standard protocols to perform the discovery and the binding. However, some interoperability concerns, such as mediating, have been still unresolved. In this work we address the integration concern of service integration in dynamic and highly evolving environments. Specifically, we have developed an integration-specific component model called CILIA. This model is based on components, called mediators, and its assembly language. CILIA respects software engineering principles such as abstraction, separation of concerns, modularity, and anticipation of change and also it is influenced by the well-known enterprise integration patterns (EIP). CILIA has been developed as a dynamic framework that allows us to perform dynamic modifications at run-time on the integrated solutions. This framework is entirely developed and operational. It is available as an open source project and has been used by several collaborative projects.

La programmation à base de composants est un paradigme de programmation qui facilite la réutilisation de code et la séparation des préoccupations. Les modèles à composants dits « reconfigurables » permettent de modifier en cours d'exécution la structure d'une application. Toutefois, ces modèles ne sont pas adaptés au calcul haute performance (HPC) car ils reposent sur des mécanismes ne passant pas à l'échelle.L'objectif de cette thèse est de fournir des modèles, des algorithmes et des outils pour faciliter le développement d'applications HPC reconfigurables à base de composants. La principale contribution de la thèse est le modèle à composants formel DirectMOD qui facilite l'écriture et la réutilisation de code de transformation distribuée. Afin de faciliter l'utilisation de ce premier modèle, nous avons également proposé :• le modèle formel SpecMOD qui permet la spécialisation automatique d'assemblage de composants afin de fournir des fonctionnalités de génie logiciel de haut niveau ; • des mécanismes de reconfiguration performants à grain fin pour les applications AMR, une classe d'application importante en HPC.Une implémentation de DirectMOD, appelée DirectL2C, a été réalisée et a permis d'implémenter une série de benchmarks basés sur l'AMR pour évaluer notre approche. Des expériences sur grappes de calcul et supercalculateur montrent que notre approche passe à l'échelle. De plus, une analyse quantitative du code produit montre que notre approche est compacte et facilite la réutilisation. / Component-based programming is a programming paradigm which eases code reuse and separation of concerns. Some component models, which are said to be "reconfigurable", allow the modification at runtime of an application's structure. However, these models are not suited to High-Performance Computing (HPC) as they rely on non-scalable mechanisms.The goal of this thesis is to provide models, algorithms and tools to ease the development of component-based reconfigurable HPC applications.The main contribution of the thesis is the DirectMOD component model which eases development and reuse of distributed transformations. In order to improve on this core model in other directions, we have also proposed:• the SpecMOD formal component model which allows automatic specialization of hierarchical component assemblies and provides high-level software engineering features;• mechanisms for efficient fine-grain reconfiguration for AMR applications, an important application class in HPC.An implementation of DirectMOD, called DirectL2C, as been developed so as to implement a series of benchmarks to evaluate our approach. Experiments on HPC architectures show our approach scales. Moreover, a quantitative analysis of the benchmark's codes show that our approach is compact and eases reuse.

First, this thesis presents an analysis of diversity of component-based software engineering (CBSE) concepts and approaches, and provides a summary of selected runtime-aware component models structured according to newly proposed criteria. As a result of the analysis, hierarchical component models are identified as a CBSE domain still not sufficiently explored in the current research with respect to their lacking penetration into regular industrial use. The major part of the thesis consequently almost exclusively focuses on problems related to application of hierarchical component models to real-life applications development. The motivations for hierarchical structuring of application architectures are presented in the thesis and key advantages of hierarchical component models are thoroughly discussed and shown on examples from commercial software development. To verify the claims, two major case-studies are presented in the thesis and the Fractal component model is successfully applied to model and implement them focusing on formal verifiability of correctness of resulting component-based applications. The thesis proposes novel approaches to model dynamic architectures changing at runtime, to deal with complex error traces and a novel specification language for component environments, all resulting from...

L’augmentation du nombre d’appareils communicants et du débit de données a pour conséquence une montée en fréquence des dispositifs micro-ondes, notamment dans le secteur du spatial. L’optimisation des modules existants n’est pas toujours suffisante. Il faut donc synthétiser de nouveaux circuits. Cependant, la plupart des méthodes de synthèse existantes, inclues dans les logiciels de CAO, ne prennent pas en compte les modèles à pertes des fondeurs. Or, plus la fréquence de fonctionnement est élevée, plus leurs prises en compte est indispensable. Cette thèse propose une nouvelle méthode de synthèse et de conception pour les circuits faible bruit intégrés (amplificateur faible bruit et mélangeur). Elle prend en compte les modèles à pertes des composants passifs des fondeurs, les lignes de connexion, les jonctions et elle combine plusieurs fonctions comme l’amplification et le filtrage ainsi que le mélange et le filtrage. Elle a été validée en simulation et en mesure. / Due to the evolution of wireless systems and data rate, it is necessary to increase microwave operating frequencies, especially in space industry. Optimization of existing circuit topologies are always not enough and therefore, we need to synthetize new circuits. Unfortunately, most of the existing synthesis methods, including in CAD softwares, are only based on lossless passive component models. With the increase of operating frequency, we need to take the effect of losses in the passive component models during synthesis. This thesis introduces a new synthesis and design method for low noise integrated circuits(low noise amplifier and mixer). Lossy passive component models from foundries, connecting wires, junctions and co-design (amplification and filtering or mixing and filtering)are included. The design procedure was validated by simulations and measurements.

Avec l'émergence de l'informatique dans les nuages, une nouvelle approche consiste à externaliser des tâches de calcul, de façon à réduire les coûts d'hébergement et à augmenter la flexibilité des systèmes. L'infrastructure actuelle des services permettant cette externalisation repose sur l'utilisation de centres de traitement de données centralisés, qui sont dédiés à l'approvisionnement de ressources de calcul. Dans cette thèse, nous étudions la possibilité de fournir de tels services en utilisant une infrastructure pair-à-pair, c'est-à-dire une infrastructure totalement décentralisée pouvant être déployée sur une fédération de noeuds de calcul hétérogénes et de provenances diverses. Nous nous focalisons sur le problème de l'allocation des noeuds et présentons Salute, un service d'allocation de noeuds, qui organise les noeuds en réseaux virtuels non-structurés et repose sur des mécanismes de prédiction de disponibilité pour assurer, avec une grande probabilité, que les requêtes d'allocation sont satisfaites dans le temps, malgré le dynamisme de l'environnement hôte. Pour ce faire, le service Salute repose sur la collaboration de plusieurs protocoles pair-à-pair appartenant à la catégorie des protocoles épidémiques. Afin de valider nos propositions, nous évaluons Salute en utilisant des traces provenant d'un échantillonnage de plusieurs systèmes pair-à-pair de référence. / With the emergence of Cloud computing, a new trend is to externalize computing tasks in order to decrease costs and increase flexibility. Current Cloud infrastructures rely on the usage of large-scale centralized data centers, for computing resources provisioning. In this thesis, we study the possibility to provide a peer-to-peer based Cloud infrastructure, which is totally decentralized and can be deployed on any computing nodes federation. We focus on the nodes allocation problem and present Salute, a nodes allocation service that organizes nodes in unstructured overlay networks and relies on mechanisms to predict node availability in order to ensure, with high probability, that allocation requests will be satisfied over time, and this despite churn. Salute's implementation relies on the collaboration of several peer-to-peer protocols belonging to the category of epidemic protocols. To convey our claims, we evaluate Salute using real traces.

The South African economy, which is largely based on heavy industry such as minerals extraction and processing, is by nature very energy intensive. Based on the abundance of coal resources, electricity in South Africa remains amongst the cheapest in the world. Whilst the low electricity price has contributed towards a competitive position, it has also meant that our existing electricity supply is often taken for granted. The economic and environmental benefits of energy efficiency have been well documented. Worldwide, nations are beginning to face up to the challenge of sustainable energy - in other words to alter the way that energy is utilised so that social, environmental and economic aims of sustainable development are supported. South Africa as a developing nation recognises the need for energy efficiency, as it is the most cost effective way of meeting the demands of sustainable development. South Africa, with its unique economic, environmental and social challenges, stands to benefit the most from implementing energy efficiency practices. The Energy Efficiency Strategy for South Africa takes its mandate from the South African White Paper on Energy Policy. It is the first consolidated governmental effort geared towards energy efficiency practices throughout South Africa. The strategy allows for the immediate implementation of low-cost and no-cost interventions, as well as those higher-cost measures with short payback periods. An initial target has been set for an across sector energy efficiency improvement of 12% by 2014. Thermal and energy system simulation is globally recognised as one of the most effective and powerful tools to improve overall energy efficiency. However, because of the usual extreme mathematical nature of most simulation algorithms, coupled with the historically academic environment in which most simulation software is developed, valid perceptions exist that system simulation is too time consuming and cumbersome. It is also commonly known that system simulation is only effective in the hands of highly skilled operators, which are specialists in their prospective fields. Through previous work done in the field, and the design of a dynamic thermal and energy system simulation scheme for cross industry applications, it was shown that system simulation has evolved to such an extent that these perceptions are not valid any more. The South African mining and commercial building industries are two of the major consumers of electricity within South Africa. By improving energy efficiency practices within the building and mining industry, large savings can be realised. An extensive investigation of the literature showed that no general suitable computer simulation software for cross industry mining and building thermal and energy system simulation could be found. Because the heating, ventilation and air conditioning (HVAC) of buildings, closely relate to the ventilation and cooling systems of mines, valuable knowledge from this field was used to identify the requirements and specifications for the design of a new single cross industry dynamic integrated thermal and energy system simulation tool. VISUALQEC was designed and implemented to comply with the needs and requirements identified. A new explicit system component model and explicit system simulation engine, combined with a new improved simulation of mass flow through a system procedure, suggested a marked improvement on overall simulation stability, efficiency and speed. The commercial usability of the new simulation tool was verified for building applications by doing an extensive building energy savings audit. The new simulation tool was further verified by simulating the ventilation and cooling (VC) and underground pumping system of a typical South African gold mine. Initial results proved satisfactory but, more case studies to further verify the accuracy of the implemented cross industry thermal and energy system simulation tool are needed. Because of the stable nature of the new VISUALQEC simulation engine, the power of the simulation process can be further extended to the mathematical optimisation of various system variables. In conclusion, this study highlighted the need for new simulation procedures and system designs for the successful implementation and creation of a single dynamic thermal and energy system simulation tool for cross industry applications. South Africa should take full advantage of the power of thermal and energy system simulation towards creating a more energy efficient society. / Thesis (Ph.D. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2005.

The South African economy, which is largely based on heavy industry such as minerals extraction and processing, is by nature very energy intensive. Based on the abundance of coal resources, electricity in South Africa remains amongst the cheapest in the world. Whilst the low electricity price has contributed towards a competitive position, it has also meant that our existing electricity supply is often taken for granted. The economic and environmental benefits of energy efficiency have been well documented. Worldwide, nations are beginning to face up to the challenge of sustainable energy - in other words to alter the way that energy is utilised so that social, environmental and economic aims of sustainable development are supported. South Africa as a developing nation recognises the need for energy efficiency, as it is the most cost effective way of meeting the demands of sustainable development. South Africa, with its unique economic, environmental and social challenges, stands to benefit the most from implementing energy efficiency practices. The Energy Efficiency Strategy for South Africa takes its mandate from the South African White Paper on Energy Policy. It is the first consolidated governmental effort geared towards energy efficiency practices throughout South Africa. The strategy allows for the immediate implementation of low-cost and no-cost interventions, as well as those higher-cost measures with short payback periods. An initial target has been set for an across sector energy efficiency improvement of 12% by 2014. Thermal and energy system simulation is globally recognised as one of the most effective and powerful tools to improve overall energy efficiency. However, because of the usual extreme mathematical nature of most simulation algorithms, coupled with the historically academic environment in which most simulation software is developed, valid perceptions exist that system simulation is too time consuming and cumbersome. It is also commonly known that system simulation is only effective in the hands of highly skilled operators, which are specialists in their prospective fields. Through previous work done in the field, and the design of a dynamic thermal and energy system simulation scheme for cross industry applications, it was shown that system simulation has evolved to such an extent that these perceptions are not valid any more. The South African mining and commercial building industries are two of the major consumers of electricity within South Africa. By improving energy efficiency practices within the building and mining industry, large savings can be realised. An extensive investigation of the literature showed that no general suitable computer simulation software for cross industry mining and building thermal and energy system simulation could be found. Because the heating, ventilation and air conditioning (HVAC) of buildings, closely relate to the ventilation and cooling systems of mines, valuable knowledge from this field was used to identify the requirements and specifications for the design of a new single cross industry dynamic integrated thermal and energy system simulation tool. VISUALQEC was designed and implemented to comply with the needs and requirements identified. A new explicit system component model and explicit system simulation engine, combined with a new improved simulation of mass flow through a system procedure, suggested a marked improvement on overall simulation stability, efficiency and speed. The commercial usability of the new simulation tool was verified for building applications by doing an extensive building energy savings audit. The new simulation tool was further verified by simulating the ventilation and cooling (VC) and underground pumping system of a typical South African gold mine. Initial results proved satisfactory but, more case studies to further verify the accuracy of the implemented cross industry thermal and energy system simulation tool are needed. Because of the stable nature of the new VISUALQEC simulation engine, the power of the simulation process can be further extended to the mathematical optimisation of various system variables. In conclusion, this study highlighted the need for new simulation procedures and system designs for the successful implementation and creation of a single dynamic thermal and energy system simulation tool for cross industry applications. South Africa should take full advantage of the power of thermal and energy system simulation towards creating a more energy efficient society. / Thesis (Ph.D. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2005.