Hydrogen is a valuable and versatile energy currency; it may be produced by harvesting solar energy and later used as a fuel to generate electricity any time of the day. This energy transaction of solar energy to hydrogen is evaluated in this work by employing a one-to-one multi-junction solar cell to proton exchange membrane combined system in a laboratory setting. Both components of the system were commercially available. The energy conversion efficiency of each isolated system was first evaluated to determine the ideal operation conditions of each respective system. For input currents in the range of 60 mA to 440 mA, the proton exchange membrane converted electrical energy to chemical potential energy with an efficiency greater than 90%. The multi-junction solar cell reached efficiencies of up to 33% while under a solar concentration of 30 Suns. The current and voltage characteristics, which resulted in the optimal operation of the isolated systems did not align and therefore, both systems were not operating at their ideal operation conditions when in the combined system. The overall energy conversion efficiency of the system was measured to be at most 19.1% under 25 Suns, an efficiency higher than systems employing traditional silicon solar cells. It was theorized that if the two system were operating under ideal conditions, the overall energy conversion efficiency would be 30.3% between 10 and 15 Suns. Methods to align the ideal operation conditions of the two systems are presented.

Le mixe énergétique du futur réseau électrique doit intégrer une grande quantité de source renouvelable intermittentes (RES). L’intermittence naturelle de ces sources sera,dans un premier moment, négligeable vis-à-vis de la stabilité du réseau électrique. Par contre,pour une large pénétration de RES, cette intermittence doit être intégrée à l'étude de la stabilité du réseau électrique. Pour une grande pénétration de RES à l'échelle européenne, un grand système de stockage d'énergie doit être mis en place. C'est déjà le cas aujourd'hui où les stations de transfert d'énergie par pompage(STEP) sont déjà utilisées. En effet, les STEP sont le moyen de stockage plus fiable et mature pour le stockage en haut puissance. Cependant,elles sont utilisées à ce jour, plutôt dans un cycle journalier et hebdomadaire d'équilibrage. La plupart des usines fonctionne de façon binaire(soit on, soit off) et ne participe pas à l'équilibrage du réseau électrique.Les nouvelles technologies envisagent de nouvelles utilisations pour les STEP. Les STEP à vitesse variable (Variable Speed PSP - de l'anglais Variable Speed Pumped Storage Plant)sont prévues de d'être utilisées en temps réel pour l'équilibrage du réseau électrique. L'objective de ce projet de ce projet est d'étudier les contributions de la STEP à vitesse variable à l'équilibrage du réseau électrique. Du point de vue du réseau, la STEP à vitesse variable est composée de deux systèmes en cascade séparés par les échelles de temps différentes. Le système peut réagir en 100ms avec la puissance nominale de la machine mais pour un temps limité (entre 5- 10s); le deuxième étage est le système hydraulique qui réagit moins vite (après 15s)mais qui peut tenir sa puissance pendant un longtemps (plusieurs heures). Ces différentes échelles de temps sont très importantes pour l'équilibrage du réseau électrique. Elles permettent que la STEP à vitesse variable soit utilisée pour différents problèmes d'équilibrage, mais comment l'utilisée reste encore un problème ouvert. Parmi d'autres,ce projet a comme objective répondre aux questions suivantes:Serait-il possible d'utiliser la STEP à vitesse variable pour l'équilibrage du réseau électrique à courant alternatif (AC) et/ou continu (DC)? Comment combiner, de façon intelligente, les réseaux continus à haute tension (HVDC - de l'anglais High Voltage Direct Current) et STEP à vitesse variable?Combinaison optimale de réaction rapide et lente pour équilibrer un réseau hybride AC et DC? La STEP à vitesse variable est-il un bon outil dynamique de stockage pour augmenter la capacité du réseau HVDC? Comment intégrer le contrôle d'une ligne HVDC et ce d'une STEP à vitesse variable?La STEP à vitesse variable peut atténuer les oscillations du réseau? / The future energy mix used toproduce electricity will include large shares ofrenewable energy sources (renewables). Theintrinsic time varying nature of these sourceswill be in the first a hinder to power systems'stability, but as their share will increase theypower of the machine but only for a limited time(typically 5 – 10 seconds); the second stage isthe hydraulic system that reacts slower (afterapprox. 15 seconds) but has a lot of energystored.These different time scales can be of uppermostUniversité Paris-SaclayEspace Technologique / Immeuble DiscoveryRoute de l’Orme aux Merisiers RD 128 / 91190 Saint-Aubin, Francemust be explicitly taken into account in thefuture when stabilizing the network. Forconstant use of renewables, in a Europe-widemanner, large storage will be capital. This isalready partially the case today, where pumpedwater storage is largely used. In fact waterstorage still is the most reliable and efficientstorage system for large amounts of power. Buttoday this is still mainly dedicated to findnight/day or weekly equilibrium of productionand consumption. These store plants are ratherplanned for an on/off utilization and do notparticipate on ancillary services (dynamicparticipation on the short term equilibrium of aninterconnection of systems or regions).New technologies allow envisaging new usesfor large storage systems. Variable SpeedPumped Storage Plants (Variable Speed PSP)are now expected to be used in real time toprovide ancillary services, effectivelyparticipating in the stabilization of powersystems. The objectives of this work are to studysome of these possibilities. It will look atdifferent aspects of stabilization: Variable SpeedPSP can be seen from the outside like a twostage systems in cascade that reacts with timeconstants that are one order of magnitude apart.The system can react within 100ms with ratedimportance when considering system's stability.They allow Variable Speed PSP to be used as thecontrol input for different stabilizationproblems, but how to do it is still an openproblem. Today these stations are only used asstandard storage, allowing the match ofproduction and consumption within a region ornetwork. The objective now is to study their useto further applications, and in particular, to studythe possibility of using them as one of the keycomponents of the future Multi-terminal HVDCnetworks. Several questions are open, this workaims to answer part of them:Is it possible to use Variable Speed PSP forancillary services (transient stability forexample) in AC and/or HVCD networks?How to combine in an intelligent way HVDCand Variable Speed PSP?Optimum combination of fast and slow reactionin order to stabilize a power grid that combinesDC and AC?Is Variable Speed PSP a good way to increasethe capability of HVDC by adding a verydynamic storage element?How to merge the control of the HVDC line andthe Variable Speed?Can this setup help to damp oscillations in thegrid?

La paralysie cérébrale (PC) cause souvent d’importants troubles de la marche. Suite à un examen clinique et une analyse quantifiée de la marche (AQM), ces troubles peuvent être traités par une chirurgie orthopédique, dite multi-sites, au cours de laquelle plusieurs corrections chirurgicales sont faites simultanément à différents niveaux des membres inférieurs. Les améliorations cinématiques apportées par ce traitement, bien que parfois très efficaces, demeurent à ce jour difficilement prévisibles. L’objectif de cette thèse est de simuler par apprentissage statistique supervisé l’effet de la chirurgie sur les signaux de marche, notamment les signaux cinématiques.Ce simulateur vise à montrer le résultat probable de la marche postopératoire afin d’aider à la décision chirurgicale. Une base de données constituée de 134 enfants atteints de PC, ayant été opérés et ayant eu au moins une AQM avant et après la chirurgie, a été exploitée. Les signaux cinématiques ont été prétraités et les données cliniques manquantes ont été imputées.Des caractéristiques des données prétraitées ont été extraites en utilisant différentes méthodes telles que l’approximation des courbes, la sélection de variables et la réduction de dimension par analyse en composantes principales. Ensuite des régressions ont été faites en utilisant différentes méthodes telles que la régression multilinéaire, la régression non linéaire avec des réseaux de neurones et l’apprentissage par ensembles. Les différentes méthodes testées ont été comparées entre elles, ainsi qu’avec d’autres méthodes trouvées dans la littérature. Il s’agit de la première fois que l’effet de la chirurgie sur la marche paralysée cérébrale est simulé de façon quantitative pour des nombreuses combinaisons chirurgicales et des nombreux patterns de marche. / Cerebral Palsy frequently leads to gait troubles. After a physical examination and a Clinical Gait Analysis (CGA), these walking troubles are usually treated by orthopedic surgery, called single event multi-level surgery (SEMLS), in which several surgical corrections are simultaneously done at different levels of the lower limbs. Kinematic improvements obtained by this treatment are sometimes very efficient, but at this moment they remain difficultly predictable. The objective of this thesis is to simulate the effect of surgery on gait parameters, using supervised statisticalmachine learning. The purpose of the simulator is to show the most likely gait outcome in order to improve decision-making in SEMLS. The database was composed of 134 children with cerebral palsy that have undergone surgery and have had at least one CGA before and after the treatment. Gait signals were preprocessed and physical examination missing data were imputed. Features of the preprocessed data were extracted using different techniques such ascurve fitting, variable selection and dimensionality reduction. Then regressions were performed utilizing different methods such as multiple linear regression, feedforward neural networks and ensemble learning. The tested methods and their performances were compared between them andto other methods in the literature. This work represents the first time that the effect of surgery on cerebral palsy gait is quantitatively simulated for a large number of surgical combinations and numerous different gait patterns.

Nos travaux portent sur l’étude du dimensionnement d’une chaîne d’actionnement au moyen d’une optimisation multi-physique. L’approche est de type « système », puisqu’il s’agit d’étudier l’association de filtres électroniques, d’un convertisseur de puissance DC-DC, d’un moteur à courant continu et d’une commande, en prenant en compte la transformation électromécanique de l’énergie ainsi que les comportements thermiques du système. L’intégration de la problématique de compatibilité électromagnétique (CEM) conduite est aussi abordée. Le travail consiste tout d’abord à modéliser chacune des physiques à prendre en compte pour chacun des sous-systèmes, puis de coupler les modèles obtenus afin de pouvoir mener des optimisations. L’algorithme d’optimisation utilisé est de type évolutionnaire. La démarche est appliquée sur le cas industriel d’une vanne EGR (Exhaust Gas Recirculation). Dans ce cadre, l’objectif est de minimiser l’encombrement du système tout en s’assurant que ses performances sont cohérentes avec le cahier des charges ainsi que les contraintes thermiques et CEM. Au-delà de l’application, la démarche permet de s’interroger sur les différents niveaux de modélisation et les moyens de couplages adéquats des modèles, dans le cadre d’une optimisation coûteuse en temps de calcul. / This thesis focuses on the design of a power conversion system using a multiphysic optimization. A system approach is applied, since the electronic filters, a DC-to-DC converter, a DC motor, and the system control are considered simultaneously. The electromechanical energy transformation is of prime importance, although the thermal behavior of the entire system is also significant. Conducted electromagnetic compatibility (EMC) issues are discussed and integrated in our approach. The first step of the methodology is the establishment of the various physical models for each sub-system. Then, these models must be coupled so that an optimization algorithm can be applied. In this work, an evolutionary algorithm is used. The approach is tested on an industrial study-case – an EGR (Exhaust Gas Recirculation) valve. In this framework, the objective is to minimize the geometrical size of the system, while ensuring that the performance imposed by the specifications is achieved and that we conform to the thermal and EMC constraints.Beyond this application, the underlying issues of the modeling level and the means of coupling the various models are addressed in the context of a time-consuming optimization.

The flock-guidance problem enjoys a challenging structure where multiple optimization objectives are solved simultaneously. This usually necessitates different control approaches to tackle various objectives, such as guidance, collision avoidance, and cohesion. The guidance schemes, in particular, have long suffered from complex tracking-error dynamics. Furthermore, techniques that are based on linear feedback or output feedback strategies obtained at equilibrium conditions either may not hold or degrade when applied to uncertain dynamic environments. Relying on potential functions, embedded within pre-tuned fuzzy inference architectures, lacks robustness under dynamic disturbances. This thesis introduces two adaptive distributed approaches for the autonomous control of multi-agent systems. The first proposed technique has its structure based on an online fuzzy reinforcement learning Value Iteration scheme which is precise and flexible. This distributed adaptive control system simultaneously targets a number of flocking objectives; namely: 1) tracking the leader, 2) keeping a safe distance from the neighboring agents, and 3) reaching a velocity consensus among the agents. In addition to its resilience in the face of dynamic disturbances, the algorithm does not require more than the agent’s position as a feedback signal. The effectiveness of the proposed method is validated with two simulation scenarios and benchmarked against a similar technique from the literature. The second technique is in the form of an online fuzzy recursive least squares-based Policy Iteration control scheme, which employs a recursive least squares algorithm to estimate the weights in the leader tracking subsystem, as a substitute for the original reinforcement learning actor-critic scheme adopted in the first technique. The recursive least squares algorithm demonstrates a faster approximation weight convergence. The time-invariant communication graph utilized in the fuzzy reinforcement learning method is also improved with time-varying graphs, which can smoothly guide the agents to reach a speed consensus. The fuzzy recursive least squares-based technique is simulated with a few scenarios and benchmarked against the fuzzy reinforcement learning method. The scenarios are simulated in CoppeliaSim for a better visualization and more realistic results.

The problem of this thesis in creative production is concerned with the use of multi-media in an oral interpretation program so as not to obscure the author's message. The production attempted to utilize literature chosen to represent a basic theme and present it with selected media so that a positive response is evoked from the audience. The study also attempts to show, through example, that a program of oral interpretation using multi-media can sustain audience interest for a full evening of entertainment. An attempt is also made to show that multi-media need not be in constant use, that some literature can best utilize the "subtractive theory" which intensifies the message by deleting a majority of media.

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Chip Multi-Processor (CMP) platforms, well-established in the server, desktop and embedded domain, succeeded in overcoming the power consumption and heat dissipation bottlenecks by integrating multiple cores, less complex and powerful than their single-core ancestors, in a single die. A major issue induced by the design of the CMPs is contention for the shared resources of the platform, Last Level Cache (LLC) and main memory bandwidth. Applications, running concurrently on the cores, compete with each other for the shared resources, and are subject to performance degradation. The way applications are assigned to the CMP, is crucial for the overall performance of the system. A scheduling policy that accounts for contention will bring high performance speed-ups, whereas an agnostic one will generate unpredictable contention conditions. For this reason the significance of the scheduler has been elevated, as it is the component that determines which applications utilize the resources each time period.In this thesis, we address cross-core interference on CMP platforms, by designing scheduling policies that improve performance and fairness. We deal with contention in three ways. In our first approach, we incorporate the notion of progress in order to balance unfairness among the applications of the workload. Performance degradation is not evenly distributed and progress greatly varies among them. In order to provide a fair execution environment, we monitor, at run-time, applications assigned to the CPU and prioritize them based on the extent at which they are affected by contention.In our second approach, we target performance by mitigating contention on shared resources. It is necessary to decide, out of all the possible application schedules, the one that generates the least amount of resource interference. To achieve that, the first indispensable step is to extract an interference profile for the applications executed on the CMP. We accomplish that by applying pressure to all levels of memory hierarchy and identifying the point at which performance is compromised. From our analysis, we understand that shared resources can tolerate pressure of certain amount; applications can be grouped together if the overall generated pressure does not reach the saturation point of the shared resources. Having extracted this information, we proceed to the placement of the application in such a way that overall resource requirements are as balanced as possible across the execution.Finally, we design a policy in order to improve performance and fairness at the same time. Applications that heavily rely on the LLC are separated from those with high main memory bandwidth, in order to avoid the destructive effects caused by the LLC thrashing behavior of the latter. The group executed on the CPU is determined based on the key observation that the overall requirements of the group should not exceed the saturation limits of the CMP. Additionally, during execution, the progress for each application is estimated and those with the least accumulated progress are prioritized.Our proposed policies are evaluated in an Intel Xeon E5-2620 v3 processor. A variety of benchmark suites were utilized to generate mixes of diverse characteristics. Our methodologies are implemented in user-space and can be deployed on Linux-based systems. Experimental results show the benefits of tackling contention in shared resources. We achieve throughput gains of up to 16% and unfairness is reduced by 2.37x on average compared to Linux scheduler.

With the growing threat of orbital debris impacts to space structures, the development of space shielding concepts has been a critical research topic. In this study, numerical simulations of the hypervelocity impact response of stacked aluminum 6061-T6 sheets were performed to assess the effects of layering on penetration resistance. This work was initially motivated by set of experimental tests where a stack of four aluminum sheets of equal thickness was observed to have a higher hypervelocity ballistic resistance than a monolithic aluminum sheet with the same total thickness. A set of smoothed particle hydrodynamic simulations predicted a 40% increase in the ballistic limit for a 6-layer target compared to a monolithic sheet. In addition, the effect of variable sheet thickness and sheet ordering on the impact resistance was investigated, while still maintaining a constant overall thickness. A set of thin layers in front of a thick layer generally lead to a higher predicted ballistic limit than the inverse configuration. This work demonstrates an increase in the performance of advanced space shielding structures associated with multi-layering. This suggests that it may be possible to dramatically improve the performance of such structures by tailoring the material properties, interfaces, and layering concepts.

Antimicrobial resistance (AMR) poses a substantial threat to public health and clinical medicine. By 2050, it’s predicted that AMR will be responsible for a yearly mortality rate of 10 million people, surpassing the mortality of cancer. Despite this daunting future we face, there are many efforts currently employed to combat the growth of AMR. One significant effort involves surveillance and early identification of novel resistant bacteria circulating in high antibiotic exposure environments. The second chapter of this thesis focuses on sampling 25 patients from a hospital environment, rich with antibiotics, to build a collection of AMR bacteria that will be tested and added to surveillance efforts/future study. This chapter allowed for the identification of several worrying AMR bacteria that provide greater insights into circulating AMR in Canadian hospitals and their patients. From the AMR collection created in chapter 2, we are also able to advance our scientific understanding of how antibiotic resistance develops within us and causes issues with treatment. In chapter 3, we looked at the effects of antibiotic administration routes on the level of AMR observed in our patient sample. We saw that current approaches to limit selection for AMR in the gut still resulted in clinically significant and concerning increases in AMR. Furthermore, this chapter allowed greater understanding of contributors to increased AMR in patients. AMR increases are not fully explained by exposure/colonization in hospital settings, but also by evolution of AMR originating from non-resistant bacteria in the gut. Additionally, analysis of these bacteria will inform expected AMR evolutionary trajectories and help us plan against them. During analysis of patient data, we also came across evolution of a less understood resistance phenotype, hetero-resistance, to a very important antibiotic, colistin. We investigated a commonly prescribed antifungal, fluconazole, for its ability to promote this resistance phenotype; however, it appeared that fluconazole did not promote this phenotype. Ultimately, this thesis serves as a valuable reservoir of AMR bacteria for future study and contributes to a greater understanding of AMR development in patients, one day leading to more informed clinical decision making. / Thesis / Master of Science (MSc)