La demande en applications gourmandes en bande passante, comme la vidéo interactive et le multimédia, s’est encore accrue rendant l’attribution de la bande passante particulièrement problématique. Ainsi, bien que le multiplexage par répartition en longueur d'onde du réseau optique passif (WDM-PON) est considéré comme un candidat prometteur pour réaliser les réseaux d'accès optiques, de nouvelles générations de systèmes hauts débits plus adaptés apparaissent grâce à la gestion d’une bande passante dédiée pour chaque abonné et de façon générale, une gestion de bande passante plus flexible. La première moitié de cette thèse porte sur trois technologies dans un WDM-PON : un système de recouvrement de multidiffusion, un système de protection automatique de commutation et de diode laser accordable Fabry-Pérot (FP-LD) en régime auto-amorcé. Dans la seconde moitié de la thèse, on étudie un réseau optique WDM distribué, utilisé pour un environnement informatique virtuel reliant des ressources informatiques largement distribuées afin de supporter des applications de calcul scientifique, d'ingénierie ou commerciale distribués à grande échelle. Ce système est ainsi appelé "grille" des systèmes optiques. Les applications de réseaux peuvent aller du simple transfert d'un grand ensemble de données à l'exécution complexe d'un ensemble de tâches interdépendantes. Cependant, dans un tel système impliquant de nombreuses ressources informatiques hétérogènes ainsi que des ressources réseau, les imperfections paraissent inévitables. Cette thèse aborde également en conséquence la question de la maximisation de la disponibilité des applications réseau en temps réel (grille de systèmes optiques) grâce à des techniques de planification des ressources et leurs tolérances face aux pannes. / The bandwidth-intensive applications, such as interactive video and multimedia services, have further increased the demand of bandwidth. Thus wavelength division multiplexing passive optical network (WDM-PON) is viewed as a promising candidate to realize the next generation optical access networks due to its dedicated bandwidth for each subscriber and more flexible bandwidth management. The first half of this thesis will cover three technologies in a WDM-PON, including multicast overlay scheme, automatic protection switching scheme and tunable Fabry-Pérot laser diode (FP-LD) self-seeding scheme. In the second half of the thesis, WDM optical network is utilized as a virtual computing environment, which connects widely distributed computing resources to support large-scale scientific, engineering or commercial computing applications. It is so called “optical Grid” systems. Grid applications may range from the simple transfer of a large data set to the complex execution of a collection of interdependent tasks. However, for such a system involving many heterogeneous computing and network resources, faults seem to be inevitable. This thesis will also address the issue of maximizing grid application availability in real-time optical Grid systems through resource-fault-tolerant scheduling techniques.

Tese de Mestrado Integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 2012

A escória de aciaria LD, principal coproduto da conversão do ferro gusa em aço, se utilizada como agregado na produção de concreto, pode reduzir custos com a estocagem de resíduos e reduzir a extração predatória de agregados naturais. Para tal, este estudo utilizou a escória de aciaria LD em substituição ao agregado miúdo do concreto, a areia, em teores de 0, 25, 50 e 75 %, em massa. O desempenho mecânico do concreto se mostrou próximo ao de referência, com exceção do módulo de elasticidade, que foi significativamente reduzido. A durabilidade dos concretos foi avaliada quanto à resistividade elétrica superficial, absorção de água, índice de vazios permeáveis, resistência à carbonatação acelerada, resistência à migração de cloretos, envelhecimento acelerado e natural. Quanto à durabilidade, apesar de verificada a redução da resistividade do concretos com escória, a substituição parcial da areia não promoveu o aumento da migração de cloretos, o que se atribui a fixação de clores pela formação de sal de Friedel; no entanto, a instabilidade volumétrica da escória se mostrou um fenômeno que gera graves patologias ao material, de modo que os corpos de prova com maior teor de substituição, após 70 dias de envelhecimento acelerado, romperam por expansão. / The basic oxygen furnace (BOF) slag, the main co-product of the process pig iron conversion to steel, if used as an aggregate in the concrete production, can reduce costs with the waste storage and reduce the predatory extraction of natural aggregates. For this, in this study the BOF slag was used in substitution to the small aggregate of the concrete, the sand, in contents of 0, 25, 50 and 75% by mass. The mechanical performance of the concrete was similar to that of reference, with the exception of the elasticity modulus, which was significantly reduced. The durability properties of the concretes were evaluated for surface electrical resistivity, water absorption, permeable voids index, resistance to accelerated carbonation, resistance to chloride migration, accelerated and natural aging. Regarding the durability, despite the reduction of the resistivity of slag concrete, the partial replacement of the sand did not promote the increase of chloride migration, which is attributed to the fixation of chlorides by Friedel Salt formation. However, the volumetric instability of the slag was a phenomenon that causes serious pathologies to the material, so that the specimens with higher substitution content, after 70 days of accelerated aging, ruptured by expansion.

Master of Engineering (Research) / Educational standards are having a significant impact on e-Learning. They allow for better exchange of information among different organizations and institutions. They simplify reusing and repurposing learning materials. They give teachers the possibility of personalizing them according to the student’s background and learning speed. Thanks to these standards, off-the-shelf content can be adapted to a particular student cohort’s context and learning needs. The same course content can be presented in different languages. Overall, all the parties involved in the learning-teaching process (students, teachers and institutions) can benefit from these standards and so online education can be improved. To materialize the benefits of standards, learning resources should be structured according to these standards. Unfortunately, there is the problem that a large number of existing e-Learning materials lack the intrinsic logical structure required, and further, when they have the structure, they are not encoded as required. These problems make it virtually impossible to share these materials. This thesis addresses the following research question: How to make the best use of existing open learning resources available on the Internet by taking advantage of educational standards and specifications and thus improving content reusability?In order to answer this question, I combine different technologies, techniques and standards that make the sharing of publicly available learning resources possible in innovative ways. I developed and implemented a three-stage tool to tackle the above problem. By applying information extraction techniques and open e-Learning standards to legacy learning resources the tool has proven to improve content reusability. In so doing, it contributes to the understanding of how these technologies can be used in real scenarios and shows how online education can benefit from them. In particular, three main components were created which enable the conversion process from unstructured educational content into a standard compliant form in a systematic and automatic way. An increasing number of repositories with educational resources are available, including Wikiversity and the Massachusetts Institute of Technology OpenCourseware. Wikivesity is an open repository containing over 6,000 learning resources in several disciplines and for all age groups [1]. I used the OpenCourseWare repository to evaluate the effectiveness of my software components and ideas. The results show that it is possible to create standard compliant learning objects from the publicly available web pages, improving their searchability, interoperability and reusability.

Ce travail de thèse est consacré à l'élaboration de composés à transition de spin et l'étude de leurs propriétés induites par irradiation lumineuse ou par une variation de la température. L'induction à l'état solide de la transition de spin par la lumière, via les effets appelés Light-Induced Excited Spin State Trapping (LIESST) et Ligand Driven Light-Induced Spin Change (LD-LISC)) a été étudiée. La préparation de nanoparticules et leur mise en forme ont été ensuite développées à partir de composés à transition de spin de nature moléculaire, puis leurs propriétés de commutation ont été examinées. Deux familles de matériaux aux propriétés optimisées pour l'étude du mécanisme de photo-conversion par effet LIESST aux temps ultra-courts ont été examinées et les premiers résultats de mesures résolues en temps sont présentés. Par ailleurs, l'étude de l'effet photomagnétique LD-LISC a été menée avec les composés de FeII(stpy)4(NCSe)2 (stpy = 4-styrylpyridine, ligand photo-isomérisable), soit en dispersant les composés dans une matrice polymérique, soit à l'état cristallin. L'influence du milieu sur la photo-réactivité du composé a été démontrée et, dans le solide cristallin, une isomérisation unidirectionnelle du ligand stpy via un mécanisme original mettant en jeu des états excités MLCT a été mise en évidence. Le développement de méthodes originales permettant la préparation de nanoparticules à transition de spin à partir de composés moléculaires a été effectuée. Tout d'abord, la chimie sol-gel a été utilisée afin d'obtenir des nano-objets dispersés dans un film mince de silice. Cette approche élégante a permis un bon contrôle de la taille des objets et l'obtention de solides de bonne qualité optique, dans lesquels une conversion thermo- et photo-induite a été observée avec le composé [FeII(mepy)3tren](PF6)2. Une autre méthode de synthèse, consistant en la précipitation rapide d'objets, éventuellement limitée par la présence de polymère a été appliquée avec succès à l'étude de plusieurs composés moléculaires à transition de spin. Avec le composé [FeIII(3-OMeSalEen)2]PF6, des objets de taille contrôlée ont été synthétisés et, de manière remarquable, un effet, relativement faible, de la réduction de taille sur la coopérativité a été observé. Enfin, l'étude de microcristaux FeII(phen)2(NCS)2, a permis de démontrer de manière indiscutable que la présence de polymère enrobant les objets pouvait influer sur leur transition thermo- et photo-induite en induisant des contraintes au niveau des particules.

Space-time coding techniques are widely used in multiple-input multiple-output communication systems to mitigate the effect of multipath fading in wireless channels. An important subset of space-time codes are linear dispersion (LD) codes, which are used for quasi-static Rayleigh flat fading channels when the channel state information (CSI) is only available at the receiver side. In this thesis, we propose a new receiver structure for LD codes. We suggest to use widely-linear minimum-mean-squared-error (WL-MMSE) estimates of the transmitted symbols in lieu of the sufficient statistics for maximum likelihood (ML) detection of these symbols. This structure offers both optimal and suboptimal operation modes. The structures of the proposed receivers in both modes are derived for general LD codes. As special cases, we study two important subsets of LD codes, namely orthogonal and quasi-orthogonal codes, and examine the performance of the proposed receivers for these codes.

Space-time coding techniques are widely used in multiple-input multiple-output communication systems to mitigate the effect of multipath fading in wireless channels. An important subset of space-time codes are linear dispersion (LD) codes, which are used for quasi-static Rayleigh flat fading channels when the channel state information (CSI) is only available at the receiver side. In this thesis, we propose a new receiver structure for LD codes. We suggest to use widely-linear minimum-mean-squared-error (WL-MMSE) estimates of the transmitted symbols in lieu of the sufficient statistics for maximum likelihood (ML) detection of these symbols. This structure offers both optimal and suboptimal operation modes. The structures of the proposed receivers in both modes are derived for general LD codes. As special cases, we study two important subsets of LD codes, namely orthogonal and quasi-orthogonal codes, and examine the performance of the proposed receivers for these codes.

La incorporació de les noves Tecnologies de la Informació i la Comunicació (TIC) al camp de l'educació ha fet possible la creació de nous entorns per l'educació que faciliten els processos d'ensenyament i aprenentatge, afegint noves eines de treball i funcionalitats i fent possible la formació per a qualsevol individu de manera no presencial i asíncrona. En aquest sentit, la Universitat Oberta de Catalunya (UOC) és una universitat sorgida de la societat de la informació que disposa del seu propi entorn virtual d'aprenentatge, un laboratori únic per a la innovació docent. Seguint la “Declaració de Bolonya” i l'Espai Europeu d'Educació Superior (EEES), el model educatiu de la UOC està centrat en el concepte d'activitat com un mitjà per a que l'estudiant assoleixi noves competències i, cada vegada més, aposta per la flexibilitat i adaptació del procés d'aprenentatge. En aquest marc, el present treball de tesi fa servir les TIC com un mitjà per a facilitar els procés d'adquisició de competències de cada estudiant. Es proposa la creació d'itineraris formatius adaptatius (IFAs) mitjançant l'especificació IMS-Learning Design (IMS-LD) per treballar la formació adaptativa. Aquesta consisteix en proporcionar als estudiants, en cada moment, les activitats i els recursos que més s'ajusten al seu perfil, oferint a cada estudiant un itinerari concret de formació. Conseqüentment, es produeix una adaptació constant a la progressió de l'estudiant que pot afavorir el seu procés d'aprenentatge, esdevenint un primer pas cap a la personalització, un dels objectius de l'EEES. Amb aquest objectiu, es descriu com es realitza tant el disseny conceptual dels itineraris formatius adaptatius, com la seva creació i implementació amb IMS-LD. També es descriu el procés d'edició i execució dels itineraris amb les eines seleccionades (ReCourse i CopperCore) i es mostren les limitacions existents per implementar la formació adaptativa i com s'han abordat. Finalment, per demostrar la seva viabilitat i aplicació real en un entorn virtual d'aprenentatge, es realitzen dues proves pilot en el marc dels estudis d'Informàtica, Multimèdia i Telecomunicació a la UOC. En aquestes proves pilot s'han implementat diferents itineraris formatius adaptatius creats amb IMS-LD, proporcionant les bases d'un primer pas cap a la introducció de la formació adaptativa en l'educació superior. / The inclusion of Information and Communication Technologies (ICT) in the field of education has made possible the creation of new environments for education that facilitate the processes of teaching and learning, adding new tools and features and making possible training for any individual using a distance and asynchronous model. The Open University of Catalonia (UOC) is a university arising from the information society that has its own virtual learning environment, a unique laboratory for educational innovation. Following the ``Bologna Declaration'' and the European Higher Education Area (EHEA), the UOC's educational model is centered on the concept of activity as a means for the student to achieve new competences and, as a distance learning institution, the UOC is increasingly committed to flexibility and adaptability of the learning process. In this context, this thesis tries to facilitate the learning process of each student by means of ICT. The work presented proposes adaptive learning paths using IMS-Learning Design (IMS-LD) in order to achieve adaptive learning. Adaptive learning provides students, at all times, activities and resources that best fits their profile, giving each student a specific learning path. Consequently, there is a constant adaptation to the progression of the students that can facilitate their learning process, becoming a first step towards personalization, one of the EHEA main objectives. Our proposal describes the conceptual design of adaptive learning paths as well as their creation and implementation using IMS-LD. It also analyzes the edition and run-time processes of the adaptive learning paths using the selected tools (ReCourse and CopperCore) showing their limitations when this adaptive scenario is taken into account and providing solutions to the encountered shortcomings. Finally, as a proof of concept, we present two different experiments performed with subjects of the department of Computer Science, Multimedia and Telecommunications of the UOC. In these experiments, different adaptive learning paths have been implemented and tested using IMS-LD, providing the basis for a first step towards the introduction of adaptive learning paths in higher education.

The seed size and shape of lentil are important traits because they determine the market class, cooking time, and can influence quality and yield of milled lentils. Understanding the genetic control of seed size and shape can help breeders develop varieties with improved seed size and shape characteristics such as seed diameter, seed thickness and seed plumpness. The objectives were to determine the heritability of seed size and shape and identify the genomic regions controlling these traits. This involved i) developing a linkage map for the LR-18 population (CDC Robin x 964a-46) using a recently developed single nucleotide polymorphism (SNP) assay; ii) analyzing the LR-18 population for seed size and shape QTLs; iii) analyzing an association mapping panel for seed size and shape QTLs. Phenotyping trials were grown at two different locations in Saskatchewan, Canada. The mapping population was grown in two different years while the association panel was only grown in one. Seed diameter and thickness were measured using sieves and this data were used to calculate seed plumpness. Days to flowering was also recorded to determine if it had any effect on seed size or shape. A linkage map consisting of 537 SNPs, 10 SSRs and 4 morphological markers on seven linkage groups was constructed and used for the QTL analysis. The heritability estimates were high for seed diameter and seed plumpness (0.92 and 0.94, respectively) while for seed thickness and days to flowering they were more moderate (0.60 and 0.45, respectively). QTL analysis revealed QTLs on five of the seven linkage groups. The association mapping study revealed similar heritability estimates of 0.97, 0.62, 0.94, and 0.62 for seed diameter, seed thickness, seed plumpness and flowering time, respectively. There were 31 different significant marker trait associations, however only 5 of those were significant for both locations. Four of those five markers did not map in the LR-18 linkage map so their genomic locations are still to be determined. Results showed that there are key regions in the genome that control seed size and shape and flowering time in lentil. These markers could be used for marker-assisted selection or for further candidate gene analysis.

The purpose of the current study is to increase the understanding of different steelmaking processes at the decarburization stages by use of mathematical modeling. More specifically, two De-Laval nozzles from a VOD (Vaccum Oxygen Decarburization) process, which is used for producing stainless steels with ultra-low carbon grades, was investigated for different vessel pressures. Moreover, the post combustion phenomena in a BOF or LD (Linz-Donawitz) process as well as an AOD (Argon Oxygen Decarburization) process were studied focusing on the decarburization stage. Two industrial VOD nozzles were numerically studied and compared at different temperatures and ambient pressures. Flow patterns of the oxygen jet under different ambient pressures were predicted and the flow information at different positions from the nozzle was analyzed. In addition, the effects of different ambient temperatures on the jet velocity and the dynamic pressure were compared. The predictions revealed that a little under-expansion is somewhat helpful to improve the dynamic pressure. The jet dynamic pressure and its width for the specific nozzle geometry were also studied. It was observed that a variation in the ambient pressure can influence the jet momentum and its width. In addition, a high ambient temperature was found to have a positive effect on the improvement of the jet dynamic pressure. Furthermore, it was found that a change in ambient pressure has a stronger effect on the jet force than a change in the ambient temperature. In addition, it was proved that the profiles of the dynamic pressure at a certain blowing distance fit well to Multi-Gaussian distribution. Post combustion in a BOF/LD and an AOD process during decarburization was also studied. Two mathematical models were created to show the post combustion phenomenon inside the converters, respectively. For the CFD modeling of the two processes, the realizable k-ɛ model, the species transport model and the discrete ordinate were adopted to calculate the turbulence, gas reaction and radiation present in the gas phase in the converter. For the BOF/LD modeling, a series of plant tests were conducted to collect data, which were used in the current model. These include the off-gas information, emissivity data, oxygen blowing parameters and the chemical composition of steel. After the simulation, the predicted flow pattern and detailed information of the gases taking part in the post combustion were compared to plant data. Specifically, the off-gas data from the plant was used for the model verification. The measured CO2 concentration was 15-20 wt% and the predicted value from the modeling was 16.7 wt%. For the AOD converter of interest in the current work, a fan is installed in the end of the AOD flue to help extract the off-gas from the converter. The influence of different fan gauge pressures as well as temperatures of the gas mixture, containing the generated CO and argon, on the post combustion in the whole AOD system was studied. It was indicated from the modeling results that the post combustion was only present in the flue for the present modeling conditions. Moreover, a critical fan gauge pressure (approx.. -550 Pa) was found which could yield a maximum post combustion in the flue gas. For both two models (BOF/LD and AOD), simulations indicated that a change of the converter temperature from 1500 to 1700 °C did not influence the post combustion reaction to a large degree. In addition, these two models can be regarded as the first step for a future more in-depth modeling work of the post combustion. / <p>QC 20130913</p>