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Le fichiers qui accompagnent mon document ont été réalisés avec le logiciel Mathematica / Dans cette thèse, nous étudions la théorie des jeux évolutionnaires dans quelques exemples de populations structurées. En particulier, nous analysons l’évolution de la coopération en déterminant des conditions qui la favorisent dans le cas des interactions par paire. On s’intéresse à l’évolution de la coopération dans un espace phénotypique de dimension quelconque. Puis on étudie la coopération dans une population finie, subdivisée en groupes de même quelconques avec une hiérarchie entre les groupes. Finalement, on présente l’effet de l’aspiration sur le processus évolutif dans une population finie répartie sur un cercle où il y a des positions à occuper. / In this thesis, we study some examples of structured populations. In particular, we analyze the evolution of cooperation in the sense of determining conditions that favor it. We study the evolution of cooperation in a phenotype space of any size. We study also the evolution of cooperation in a finite population subdivided into hierarchical groups of any size. Finally, we study the effect of aspiration on the evolutionary process in a finite population distributed on a circle with only a local interaction by pairwise.

Depuis plusieurs décennies, une importante activité scientifique se concentre sur la description numérique, théorique ou expérimentale de l'hydrodynamique des écoulements multiphasiques. Ces écoulements sont caractérisés par l'existence d'interfaces, et d'une force à l'interface, la tension superficielle, séparant généralement deux fluides non miscibles. Un cas d'étude dans ce contexte est le problème du drainage d'une unique goutte dans une phase continue, l'ensemble étant soumis à la gravité. Ce système fait apparaître des écoulements récemment décrits pour une goutte d'eau dans l'huile de paraffine. Ce système constitue également un modèle simple pour l'étude des propriétés aux interfaces, Mais d'un point de vue numérique, se pose alors le problème de la stabilité des algorithmes pouvant être utilisés. Les effets aux interfaces impliquent en effet des domaines spatiaux très limités dans lesquels les grandeurs physiques entre les deux fluides sont discontinues. D'importants artéfacts numériques peuvent alors être générés dans les simulations et faire perdre la richesse de la physico-chimie du système considéré. Le problème de la simulation d'écoulements multiphasiques intéresse aussi bien le monde académique que le monde industriel. L'objectif de ce travail de thèse est donc d'implémenter les techniques numériques les plus récentes et de développer un code pour permettre la simulation de l'hydrodynamique de systèmes dispersés. Pour parvenir à ce but, il reste encore des problèmes algorithmiques importants à résoudre comme la prise en compte des effets thermocapillaires et thermosolutaux. Ces deux derniers points sont l'objet de cette thèse. / For several decades, an important scientific activity has focused on the numerical, theoretical and experimental hydrodynamics of drops. This work presents numerical results of a single droplet in the gravity field and in non-isothermal conditions. The simulation such a multiphase system is important in both academic and industrial world. This is particularly the case in the field of emulsions, wetting problems and evaporation. To achieve this goal, there are still important algorithmic problems due to the free moving interfaces and the description of capillary effects. Here, a Volume of Fluid technique has been implemented with high order temporal and spatial schemes to preserve the sharpness of the drop interface. The system under consideration is a simplified model consisting in a single water droplet in a continuous paraffin oil phase. These liquids are immiscible and non-compressible and the overall evolution is unsteady. Capillary contributions such as temperature and surfactant dependent surface tension are fully accounted for. This presentation is aimed to show the capabilities of VOF techniques for the simulations of unsteady multiphase systems in non-isothermal configurations. The role of the droplet initial position and temperature field is described with good numerical stability. There are still important problems remaining in the simulation of free interface systems with such a technique. Spurious currents induced by the description of capillarity can in particular come into play. But these latter can be controlled once the droplet average velocity due to drainage becomes large enough.

GaN-Nanodrähte können mit einer hohen strukturellen Perfektion auf verschiedenen kristallinen und amorphen Substraten gewachsen werden. Sie bieten somit faszinierende Möglichkeiten, sowohl zur Untersuchung von fundamentalen Eigenschaften des Materialsystems, als auch in der Anwendung in optoelektronischen Bauteilen. Obwohl bereits verschiedene Prototypen solcher Bauteile vorgestellt wurden, sind viele grundlegende Eigenschaften von GaN-Nanodrähten noch ungeklärt, darunter die interne Quanteneffizienz (IQE), welche ein wichtiges Merkmal für optoelektronische Anwendungen darstellt. Die vorliegende Arbeit präsentiert eine detaillierte Untersuchung der Rekombinationsdynamik von Exzitonen, in selbst-induzierten und selektiv gewachsenen GaN Nanodraht-Proben, welche mit Molekularstrahlepitaxie hergestellt wurden. Die zeitaufgelösten Photolumineszenz (PL)-Experimente werden durch Simulationen ergänzt, welche auf Ratengleichungs-Modellen basieren. Es stellt sich heraus, dass die Populationen von freien und gebundenen Exzitonen gekoppelt sind und zwischen 10 und 300 K von einem nichtstrahlenden Kanal beeinflusst werden. Die Untersuchung von Proben mit unterschiedlichem Nanodraht-Durchmesser und Koaleszenzgrad zeigt, dass weder die Nanodraht-Oberfläche, noch Defekte als Folge von Koaleszenz diesen nichtstrahlenden Kanal induzieren. Daraus lässt sich folgern, dass die kurze Zerfallszeit von Exzitonen in GaN-Nanodrähten durch Punktdefekte verursacht wird, welche die IQE bei 10 K auf 20% limitieren. Der häufig beobachtete biexponentiellen PL-Zerfall des Donator-gebundenen Exzitons wird analysiert und es zeigt sich, dass die langsame Komponente durch eine Kopplung mit Akzeptoren verursacht wird. Motiviert durch Experimente, welche eine starke Abhängigkeit der PL-Intensität vom Nanodraht-Durchmesser zeigen, wird die externen Quanteneffizienz von geordneten Nanodraht-Feldern mit Hilfe numerischer Simulationen der Absorption und Extraktion von Licht in diesen Strukturen untersucht. / GaN nanowires (NWs) can be fabricated with a high structural perfection on various crystalline and amorphous substrates. They offer intriguing possibilities for both fundamental investigations of the GaN material system as well as applications in optoelectronic devices. Although prototype devices based on GaN NWs have been presented already, several fundamental questions remain unresolved to date. In particular, the internal quantum efficiency (IQE), an important basic figure of merit for optoelectronic applications, is essentially unknown for GaN NWs. This thesis presents a detailed investigation of the exciton dynamics in GaN NWs using continuous-wave and time-resolved photoluminescence (PL) spectroscopy. Spontaneously formed ensembles and ordered arrays of GaN NWs grown by molecular-beam epitaxy are examined. The experiments are combined with simulations based on the solution of rate equation systems to obtain new insights into the recombination dynamics in GaN NWs at low temperatures. In particular, the free and bound exciton states in GaN NWs are found to be coupled and affected by a nonradiative channel between 10 and 300 K. The investigation of samples with different NW diameters and coalescence degrees conclusively shows that the dominating nonradiative channel is neither related to the NW surface nor to coalescence-induced defects. Hence, we conclude that nonradiative point defects are the origin of the fast recombination dynamics in GaN NWs, and limit the IQE of the investigated samples to about 20% at cryogenic temperatures. We also demonstrate that the frequently observed biexponential decay for the donor-bound exciton originates from a coupling with the acceptor-bound exciton state in the GaN NWs. Motivated by an experimentally observed, strong dependence of the PL intensity of ordered GaN NW arrays on the NW diameter, we perform numerical simulations of the light absorption and extraction to explore the external quantum efficiency of these samples.

La façon dont les musiciens parviennent à reconnaître les notes, par l’écoute seule ou en pratiquant leur art, a toujours fait l’objet d’une certaine fascination. Eux-mêmes, du reste, ne savent que rarement les raisons particulières qui leur permettent de disposer ainsi d’une excellente oreille musicale : « on est doué ou on ne l’est pas » reste alors souvent le raccourci qui permet de ne pas s’aventurer plus loin dans la quête d’une véritable explication. Il faut bien admettre que cette propension à pouvoir identifier des hauteurs perçues paraît ne pas trouver de véritable fondement, et ce d’autant plus que le son musical se trouve être invisible, impalpable et relativement fugace. Pour tenter de mieux comprendre les raisons liées à cette capacité mystérieuse, nous avons pris le parti d’interroger des musiciens, professionnels ou en apprentissage, afin de les questionner sur les procédures mentales qu’ils mettent en oeuvre à l’instant de l’identification notale. La description détaillée des plus petits éléments mentaux (ou la plus petite cohabitation de microéléments mentaux) que les musiciens utilisent pour effectuer cette tâche nous fait alors entrer dans un monde fascinant, qui révèle progressivement l’organisation de nombreuses actions de bas niveau, aussi ajustées à leurs fonctions que particulièrement discrètes. Ces fragments de pensées, que nous avons nommés appuis mentaux (les musiciens se repèrent en fonction de points d’ancrages mentaux adaptés pour accéder à l’identification) peuvent être décrits, sont variés dans leurs formes d’émergence à l’esprit et adoptent différents types de missions. Il a été possible de classer l’ensemble des configurations décrites en plusieurs catégories d’approches stratégiques. Certains de ces infimes gestes internes se sont tellement automatisés au fil du temps qu’ils se trouvent enfouis dans le registre inconscient. Ils deviennent alors très difficiles, voire parfois impossibles à détecter. En y regardant de plus près, nous pouvons imaginer que ces mécanismes hautement spécialisés, décrits dans un secteur restreint du monde musical, relèvent de principes fonctionnels généraux qui semblent s’activer, en réalité, à tout instant de notre vie quotidienne, pour chaque opération que nous sommes appelés à effectuer : calculer, orthographier, créer, faire du sport, cuisiner, bricoler ou bien penser tout simplement. C’est ce que la seconde partie de recherche tente de montrer dans un premier temps, pour exposer ensuite une bien étrange problématique, concernant les rapports interactifs qui s’opèrent entre contenus perceptifs et représentationnels (de nombreux témoignages font en effet état de situations où les appuis mentaux s’invitent directement sur la scène perceptive). La confrontation de ces deux univers, à travers le maniement de ce que nous avons appelé les reprojections mentales, nous met en situation de questionner les rouages qui sont en jeu dans l’édification de la cognition humaine, et interroge sur les conséquences qu’ils impliquent vis-à-vis de notre compréhension du réel. / The way musicians identify notes has always been a fascinating subject. In order to understand this competence of theirs, we have opted to interview professional and learner musicians so as to analyse the mental methods they use to fulfil this task. A detailed description of the faintest mental processes involved in so doing opens on a bewildering world which exposes an organisation of many low level actions as adapted to their functions as they are subtle. These fragments of thoughts - which we have called mental anchor points - can be described, are varied in their ways of surfacing and can engage in diverse mission types. When subjected to closer scrutiny, we can imagine that these highly specialised mechanisms fall within the sphere of general functional principles which seem to be active at every moment of our lives, for whichever operation we try to perform: calculating, taking part in sports activities, cooking or simply thinking. This is what the second part of this study first tries to show, before disclosing a strange system of issues concerning interactive relations between perceptions and representations. Many testimonies mention situations in which mental anchor points play a prominent part in our perceptive behaviour. The confrontation of these two universes, thanks to the use of what we have called mental reprojections, makes it possible for us to examine the machinery at stake in our cognitive constructions and to analyse the consequences they imply concerning our comprehension of the real world.

L'objet de ce travail est de mieux comprendre ce qui se produit lorsque l'on perturbe un système complexe, en utilisant les automates cellulaires comme modèle. Nous nous intéressons principalement à deux perturbations. La première concerne l'écoulement du temps : contrairement au modèle habituel, nous utilisons des mises à jour asynchrones, c'est-à-dire que, à chaque étape, seulement une partie des cellules sont mises à jour. L'autre perturbation concerne la topologie, c'est-à-dire le graphe d'interaction entre les cellules.<br>Une première partie étudie expérimentalement l'apparition de la percolation dirigée dans les automates cellulaires, notamment dans le cadre du "damage spreading". Le dernier chapitre de cette partie prouve une équivalence entre une classe d'automates cellulaires probabilistes et les automates cellulaires asynchrones.<br>La seconde partie étudie dans un premier chapitre l'interaction des deux perturbations évoquées: asynchronisme et topologie. Alors que le modèle habituel utilise une grille Zd, nous étudions une grille où certains liens sont temporairement coupés. Puis un second chapitre démontre des propriétés théoriques sur la règles minorité lorsque la topologie est un arbre.<br>Nous avons dans cette thèse mené à la fois des études expérimentales et des études théoriques. Une préoccupation transversale est la simulation formelle entre modèles. L'enjeu de ces travaux est, à terme, de savoir comment obtenir des systèmes ayant un comportement global prédéfini, ou bien comment rendre robuste à certaines perturbations un système complexe donné.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

The wettability and phase change phenomena of water are ubiquitous on biological and artificial surfaces. Properties like water repellency, self-cleaning, coalescence induced condensation jumping, anti-frosting, and dew harvesting arise on surfaces with particular structures and chemistry and are of particular interest for energy and water saving. This thesis collects different studies of wettability and phase change on natural and artificial surfaces: growth and self-ejection of condensation droplets on micro and nanostructured surfaces we fabricated, their applications, the Sliding on Frost of condensation droplets observed on the Cotinus Coggygria leaf, the dew harvesting property of the Old Man of the Andes Cactus enhanced by distance coalescence through microgrooves and finally, a theoretical study of viruses viability in sessile droplets. The first chapter introduces the theoretical framework of wettability and phase changes on surfaces. In the second chapter, we present the self-ejection of condensation droplets from hydrophobic nanostructured microstructures. We modelled analytically the droplets jumping and fabricated surfaces to verify the predictions. The fabricated geometry was inspired by the modelling and the available fabrication techniques. We tested the surfaces in condensation conditions. Using a high frame rate camera coupled with a long working distance microscopy objective, we investigated the growth and ejection transient. We then compared the experimental self-ejection velocity for various structures geometry with our analytical models. In Chapter 3, we investigated the applications of the fabricated surfaces reported in Chapter 2. In Chapter 4, we explore the condensation frosting on the leaf of Cotinus Coggygria, native of our woods and with interesting hydrophobic properties. Covered by wax nanotubules, it exhibits coalescence-induced condensation jumpings that may be a useful cleaning tool. Furthermore, the frost is delayed but not only for the jumping. Surprisingly, at temperatures some degrees below zero, we observed what we called ‘droplet Sliding on Frost bridges’, that further delays frosting. We described the feasibility of this sliding in terms of dynamic contact angles of the surface and contact angles of supercooled water on ice. By capturing high temporal and spatial resolution videos we investigated the sliding on frost and droplet recalescence (fast dendrite growth that partially solidify the liquid). The responsible for the failure of sliding for temperatures from about -8 ° C down appears to be the advancing angle of water on ice that increases with the subcooling rather than the recalescence that blocks the drop in place. These results add a piece to the fundamental research on the supercooled water-ice-vapour interfaces. As it often happens, biological surfaces offer a starting point for the study of fundamental mechanisms and the development of artificial surfaces with optimized properties. In the Chapter 5, the multifunctional roles of hairs and spines in Old Man of the Andes Cactus (Oreocereus trolli) are studied. We study the morphology of the appendages, the hairs wettability, mechanical properties of both, and the dew formation on spines. The longitudinal microgrooves on the spines cause a particular phenomenon of distant coalescence (DC), in which smaller droplets flow totally or partially into larger ones through the microgrooves, with consequent accumulation of water in a few large drops. An earlier study has shown artificial micro-grooved surfaces that exhibit DC are more efficient than flat ones at collecting and sliding dew, and thus these cactus spines could act as soil dew conveyors. The agreement between our analytical model and experimental data verifies that the flow is driven by the Laplace pressure difference between the drops. This allowed us to obtain a general criterion for predicting the total or partial emptying of the smaller drops as a function of the dynamic contact angles of a surface. Based on this criterion, an hydrophilic material with small contact angle hysteresis would allow a greater number of complete drops emptying. The COVID-19 pandemic has raised the problem of contagion from airborne and deposited droplets. In the last chapter, we report the state of the art of experiments on the viability of viruses in deposited droplets. Up to date, it has been experimentally highlighted that the relative viability of some viruses (RV) depends on the material chemistry, temperature, and interestingly, on relative humidity (RH) with a U-shaped trend. One of the current hypotheses is that the cumulative dose of salt concentration (CD) affects RV. We model the RV of viruses in sessile droplets by inserting a RV-CD relation in a model of droplet evaporation. By considering a saline water droplet (one salt) as the simplest approximation of real solutions, we analytically simulate the time evolution of salt concentration, vapor pressure, and droplet volume varying contact angles, droplet sizes, and RH in the range 0–100%. The results elucidate some previously not yet well-understood dynamics, demonstrating how three main regimes—directly implicated in nontrivial experimental trends of virus RV—can be recognized as the function of RH. The proposed approach could suggest a chart of a virus fate by predicting its survival time at a given temperature as a function of RH and contact angle. We found a good agreement with experimental data for various enveloped viruses and predicted in particular for the Phi6 virus, a surrogate of coronavirus, the characteristic U-shaped dependence of RV on RH. Given the generality of the model, once experimental data are available that link the vulnerability of a certain virus (such as SARS-CoV-2) to the concentrations of salts or other substances in terms of CD, it is envisioned that this approach could be employed for antivirus strategies and protocols for the prediction/reduction of human health risks associated with SARS-CoV-2 and other viruses.

<p>  </p> <p>Water scarcity is a global problem impacting a majority of the world population. A significant proportion of the global population is deprived of clean drinking water, an impact felt by the rural as well as urban population. Saltwater desalination provides an attractive option to produce clean water. Some technologies to generate potable water include reverse osmosis (RO), multi-stage flash distillation (MSF), vapor compression distillation and multi-effect distillation (MED). Distillation plants such as those in MED often have falling-film evaporators operating at low energy conversion efficiency and hence distillation is performed over multiple stages (or effects). Porous materials can be utilized as evaporators in such plants with the objective of leveraging their superior efficiency. This can potentially decrease the number of effects over which distillation occurs. However, evaporation of high-salinity salt solution eventually results in salt precipitation which can cause fouling and induce structural damages, especially if the precipitates appear within the porous medium. Crystallization-induced structural damages are also of significant concern to building materials and for their role in weathering of historical monuments. It is thus crucial to understand the mechanisms governing salt precipitation in a porous medium.</p> <p>Transport of solute in such a medium is either driven by flow of the solution (advection) or by concentration gradients (diffusion). The dynamics of solute transport is further complicated due to the involvement of a reaction term accounting for any salt precipitation. The relative strengths of these driving forces determine the solute transport behavior during an evaporation-driven process. The wide-scale applications of solute transport and its complicated nature warrant investigation, both experimental and theoretical, of the dependence of solute transport and the subsequent precipitation on the operating conditions and the properties of the porous medium.</p> <p>This dissertation first focuses on developing a novel modeling framework for evaluating the transient behavior of the solute mass fraction profile within the domain of a one-dimensional porous medium, and extending its capability to predict the formation of salt precipitate in the medium.  Experimental investigations are then performed to study the formation of precipitate on sintered porous copper wicks of different particle-size compositions, and developing a mechanistic understanding of the governing principles.</p> <p>A numerical modeling framework is developed to analyze evaporation-driven solute transport. Transient advection-diffusion equations govern the salt mass fraction profile of the solution inside the porous medium. These governing equations are solved to obtain the solute mass fraction profile within the porous medium as well as the effloresced salt crust. Further accounting for precipitation allows a study of the formation and growth of efflorescence and subflorescence. Crystallization experiments are performed by allowing a NaCl solution to evaporate from a porous medium of copper particles and the subflorescence trends predicted by the model are validated. The modeling framework offers a comprehensive tool for predicting the spatio-temporal solute mass fraction profiles and subsequent precipitation in a porous medium.</p> <p>The dependence of efflorescence pattern on the properties of a porous medium is also investigated. Efflorescence patterns are visually observed and characterized on sintered copper particle wicks with spatially unimodal and bimodal compositions of different particle sizes. Efflorescence is found to form earlier and spread readily over a wick made from smaller particles, owing to their lower porosity, while it is limited to certain areas of the surface for wicks composed of the larger particles. A scaling analysis explains the observed efflorescence patterns in the bimodal wicks caused by particle size-induced non-uniform porosity and permeability. The non-uniformity reduces the advective flux in a high-permeability region by diverting flow towards a low-permeability region. This reduction in advective flux manifests as an exclusion distance surrounding a crystallization site where efflorescence is not expected to occur. The dependence of this exclusion distance on the porosity and permeability of the porous medium and the operating conditions is investigated. A large exclusion distance associated with the regions with bigger particles in the bimodal wicks explains preferential efflorescence over the regions with smaller particles. This novel scaling analysis coupled with the introduction of the exclusion distance provides guidelines for designing heterogeneous porous media that can localize efflorescence.</p> <p>Additionally, droplet interactions with microstructured superhydrophobic surfaces as well as soft surfaces were investigated during the course of this dissertation, separate from the above investigations. These investigations involve the interplay of surface energies with electrical or elastic energies and are studied both experimentally and through theoretical models, and therefore are retained as additional chapters in the thesis as being of relevant interest.  Electrowetting experiments are performed on superhydrophobic surfaces with re-entrant structures to study their resilience to the Cassie-to-Wenzel transition. The deformation of soft surfaces caused by forces exerted by microscale droplets is studied and the resulting interaction between multiple droplets is explored. </p>