L’intégration monolithique de matériaux semi-conducteurs III-V sur substrat de Silicium est essentielle pour le développement de la photonique sur Silicium. L’objectif est de réaliser une micro-source optique à base d’un réseau ordonné de Nanofils (NFs) III-V (InAsP/InP) placés sur un guide d’onde Si. De par leur aptitude à relaxer les contraintes, les NFs sont d’un grand intérêt. C’est dans ce contexte que s’est déroulée cette thèse axée sur la croissance autocatalysée de NFs InP sur Silicium par épitaxie directe. Nous avons ainsi montré que la croissance auto-catalysée de NFs InP denses et verticaux dépend directement de la nature de l’oxyde de surface du substrat Si. Une distribution monomodale ou bimodale de NFs ont été achevées en fonction des conditions de formation des gouttelettes d’indium ou des paramètres de croissance. Une pression critique et une température critique ont permis de délimiter des domaines favorables à la croissance. Les propriétés optiques intrinsèques des NFs ont été déterminées suffisantes pour l’objectif visé. Enfin, des résultats sur la simulation optique et la polarisation de la lumière émise dans les NFs et le guide d’onde ont permis d’établir un cahier des charges pour la croissance des NFs verticaux sur SOI pour que le couplage/partage de leurs modes optiques soit le plus efficace possible aux longueurs d’onde télécom. / Monolithic integration of III-V semiconductors materials on Si substrate is essential for the Si photonic development. We aim at achieving an optical microsource based on a regular array of III-V (InAsP/InP) nanowires (NWs) standing on top a Si waveguide. Due to their ability to be fully relaxed, nanowires growth is of deep interest. This PhD thesis has been oriented towards such context especially among self-catalyzed InP NWs growth by epitaxy. Thus we have shown that highly dense and vertical self-catalyzed InP NWs accomplishment is related to Si substrate surface oxide. A monomodal or bimodal NWs distribution have been reached through a control of indium droplets formation or growth parameters. A critical pressure and a critical temperature have been found to delimit favorable growth regime. Intrinsic optical properties have been determined to be goal sufficient. Optical simulation modeling and characterization of the polarization light state in NWs and in the Si waveguide have led us to establish functional specifications to grow vertical NWs on SOI as way that their optical modes could be coupled efficiently at telecommunications wavelength.

Utilisés pour leur bon compromis entre propriétés mécaniques, thermiques et électriques, les alliages Cu-Ni-Si à durcissement structural par précipitation sont notamment employés pour la maintenance ferroviaire. Ils sont donc soumis aux passages des trains et aux effets d’environnement. C’est pourquoi la résistance d’un alliage CuNi2Si a été étudiée en fatigue oligocyclique, en corrosion aqueuse et en fatigue-corrosion. Le but est de relier les propriétés macroscopiques aux mécanismes microstructuraux. Les essais de fatigue ont montré un durcissement initial de l’alliage, suivi d’un adoucissement continu jusqu’à la rupture. À l’aide des microscopies électroniques en transmission (MET) et à balayage (MEB), notamment en ECCI (Electron Channeling Contrast Imaging) et en EBSD (Electron BackScattered Diffraction), une formation initiale de cellules de dislocations a été identifiée, ces dernières disparaissant au profil de la formation de bandes dénuées de précipités suite à la dissolution mécanique des précipités δ-Ni2Si. Ceci constitue le mécanisme d’accommodation de la déformation cyclique. L’avancée de la formation de ces bandes explique les différents régimes observés sur le diagramme de Manson-Coffin. L’alliage présente en milieu NaCl à 50 g.L1 un mécanisme de corrosion intergranulaire. La spectroscopie d’impédance électrochimique (SIE) semble indiquer la présente d’un film passif compact en surface de l’alliage. Enfin, une sensibilité à la fatigue-corrosion apparaît, notamment aux plus hauts niveaux de déformation où la durée de vie est réduite d’un tiers. De plus, un faciès de rupture semblable à ceux observés en corrosion sous contrainte est constaté. / Employed for their good balance between mechanical, thermal and electrical properties, precipitation hardened Cu-Ni-Si alloys are used for various purposes, including railway maintenance. In the latter case, they are submitted to train traffic and environmental effects. This is why the low cycle fatigue (LCF), the wet corrosion and the fatigue-corrosion behaviours of a CuNi2Si alloy have been studied. The aim of the present work is to relate the macroscopic properties to the microstructural behaviour. The fatigue life of the alloy is composed of an initial hardening step, followed by a continuous softening until fracture. Thanks to the combination of transmission and scanning electron microscopies (respectively TEM and SEM), including ECCI (Electron Channeling Contrast Imaging) in addition to EBSD (Electron BackScattered Diffraction), the formation of dislocation cells has been identified, which ones are then consumed by the formation of precipitate free bands after the mechanical dissolution of the δ-Ni2Si precipitates. This sequence describes the cyclic strain accommodation mechanism. The progress in the formation of these bands explains the different regimes observed into the Manson-Coffin diagram. The alloy exhibits intergranular corrosion in 50 g.L-1 NaCl solution. The electrochemical impedance spectroscopy (EIS) indicates the formation of a compact passive film at the surface of the alloy. Finally, the alloy seems to be sensible to fatigue-corrosion, especially at high strain range where the number of cycle to failure is reduced by a third. Moreover, a fracture surface similar to a stress corrosion cracking surface is also observed.

Nous avons étudié les deux structures concessives en français moderne si p, q et même si p, q. Dans le premier chapitre, nous avons résumé certaines études antérieures sur divers sujets. La section sur la concession montre qu'il y a sous-entendue a une phrase telle que même si Jacques est la, je vais partir un rapport du genre si Jacques est Id, je ne vais pas partir; autrement dit, même si p, q implique si p,~ q (Moeschler & de Spengler, Martin, Ducrot). Par contre, une phrase telle que s'il est intelligent, il est brouillon se glose mieux par la paraphrase de Nguyen certes p, mais q: certes il est intelligent, mais il est brouillon. Dans la section sur la valeur de base des phrases en si p, q (concessives ou non concessives), on voit que si est le marqueur d'une supposition, et cette supposition sert comme cadre pour l'énonciation de q qui suit. La section sur même montre que ce mot est le marqueur d'une échelle argumentative (Ducrot), et qu'il est limite par le contexte et« ce à quoi on s'attendrait» (Lycan). Dans le deuxième chapitre, nous avons décrit notre corpus, et nous avons déterminé si les diverses structures proposées au chapitre précédent étaient présentes dans les exemples du corpus. La section sur si concessif montre que la paraphrase certes p, mais q peut toujours paraphraser les phrases concessives de la structure si p, q. Cependant, la structure si p,~ q est aussi présente, mais indirectement. Finalement, nous avons fait certaines observations sur le temps des verbes dans les deux propositions/? et q, et nous avons étudié les combinaisons présent/présent, imparfait/imparfait, passé composé/présent, et plus-que-parfait/imparfait. Les deux premières combinaisons montrent une opposition—par rapport aux si non concessifs— au niveau des temps verbaux, les deux dernières au niveau de l'aspect. La section sur les cas de même si révèle d'une part que toutes les phrases de cette structure possèdent la structure sous-entendue si p, ~ q, et d'autre part que certains exemples acceptent aussi la paraphrase de Nguyen. Ceci correspond à la distinction qu'Eriksson fait des phrases en même si portant sur des faits réels et non réels (virtuels). / Arts, Faculty of / French, Hispanic, and Italian Studies, Department of / Graduate

Turbocharged spark-ignited engines may encounter stochastic events of premature ignition of the fuel-air mixture, termed as pre-ignition. Pre-ignition often leads to extremely high peak pressure and pressure oscillations, causing engine damage. A review of pre-ignition in historic times is done in this dissertation, and the similarities and differences compared to modern pre-ignition issue are brought forth. Experiments conducted with varying injection strategies yielded varying pre-ignition tendency. The pre-ignition tendency correlated with the charge cooling tendency and the mass of liquid fuel impinging on the cylinder liner and diluting the oil film. The diluted oil is trapped in the piston ring area and from time-to-time gets launched into the combustion chamber near top dead center. The fuel-oil mixture droplet may ignite the surrounding charge before the spark timing. Experiments conducted with varying exhaust back pressure showed dependence of pre-ignition tendency on in-cylinder temperature near top dead center, for cases when intake pressure is higher than exhaust pressures. For exhaust pressure higher than intake pressure, fuel wall impingement was critical to pre-ignition. This research also devised ion-current based sensors for pre-ignition detection. Initial experiments were done with DC-power based ion-current sensor, which detected a pre-ignition event when a flame brushed past the sensor. There was a need of faster-response sensor with high signal-to-noise ratio, that would allow pre-ignition detection at its inception stage, thereby giving enough time to trigger an evasive action. In this regard, an AC-powered ion-current sensor was devised and patented. Sudden fuel enrichment at the time of pre-ignition detection was investigated as an evasive method. Various strategies were investigated for their pre-ignition suppression tendency. Split injection, water injection, Octane-on-Demand, injecting different fluids in late compression stroke and dual fuel operation with gasoline and methane were found to be highly effective at suppressing pre-ignition completely. Use of ethanol in blends with different FACE gasolines is investigated to suggest fuel effects on pre-ignition. The strategies were successful at either reducing the mass of liquid fuel impinging the liner, reducing the in-cylinder temperature near top dead center or reducing the potential of residual gas content to trigger pre-ignition in the next cycle.

Polymer based microelectromechanical systems (MEMS) micromachining is finding more interest in research and applications. This is due to its low cost and less time processing compared with silicon MEMS. SU-8 is a photo-patternable polymer that is used as a structural layer for MEMS and microfluidic devices. In addition to being processed with low cost, it is a biocompatible material with good mechanical properties. Also, amorphous silicon (α-Si) has found use as a sacrificial layer in silicon MEMS applications. α-Si can be deposited at large thicknesses for MEMS applications and also can be released in a dry method using XeF2 which can solve stiction problems related to MEMS applications. In this thesis, an SU-8 MEMS process is developed using amorphous silicon (α-Si) as a sacrificial layer. Electrostatic actuation and sensing is used in many MEMS applications. SU-8 is a dielectric material which limits its direct use in electrostatic actuation. This thesis provides a MEMS process with two conductive metal electrodes that can be used for out-of-plane electrostatic applications like MEMS switches and variable capacitors. The process provides the fabrication of dimples that can be conductive or non-conductive to facilitate more flexibility for MEMS designers. This SU-8 process can fabricate SU-8 MEMS structures of a single layer of two different thicknesses. Process parameters were tuned for two sets of thicknesses which are thin (5-10μm) and thick (130μm). Chevron bent-beam structures and different suspended beams (cantilevers and bridges) were fabricated to characterize the SU-8 process through extracting the density, Young’s Modulus and the Coefficient of Thermal Expansion (CTE) of SU-8. Also, the process was tested and used as an educational tool through which different MEMS structures were fabricated including MEMS switches, variable capacitors and thermal actuators.

Been There Together is a single player game in an online and offline form of cards inspired by event scores. The game is designed to be played by individuals in public spaces, while they are surrounded by strangers. It serves as a pretext for social inclusion. The game can be played online, as a mobile phone application and as a DIY card game for download. The game was designed as an alternative to mobile games, and instead of pulling the player into a virtual reality, it encourages their perception of society and the surroundings. By providing challenges, context and aesthetic pleasure, it creates an exciting experience that contrasts with ordinary daily activities. Its purpose is to overcome the individual's alienation in society. By simple questions and tasks, the player is drawn into a magic circle of play in reality, in areas that are not normally intended for play. It creates a temporary world in the midst of an ordinary world, transforming everyday experience and the individual's perception of public spaces. The game is inspired by Fluxus group's "event scores" as well as by the Situationist International's concept of "dérive", a method of unplanned journeying through urban landscapes. The player can choose between 4 difficulty levels and decide which intensity of play they prefer. Its unobtrusive design allows the player to play the game without noticeably changing their behaviour in public, and it is entirely their decision if they want to admit that they are playing the game to bystanders. Thanks to the guise of a game, the player feels safe to interact with a stranger, to ask for help or to ask questions of people whom they are encountering for the first time. The game creates real social interaction, with legal and economic consequences that reach beyond the magic circle.

This thesis is focused on adsorption of phthalocyanines on tin and indium passivated silicon Si(111) surfaces with the √3 × √3 reconstruction at room temperature. Scanning tunneling microscopy was used for obtaining atomically resolved surface images. Molecules on these surfaces predominantly adsorb on Si-substitutional defects. Local density of states (LDOS) of strongly adsorbed molecules was obtained by scanning tunneling spectroscopy. The origin of fuzzy imaging of molecules sitting on Si-substitutional double defects was probed. Voltage dependence of mean lifetime of two observed states, between which the "fuzzy" molecule is switching, was measured by analysis of tunneling current fluctuations. We discussed the influence of external parameters on the switching between the two states. We attribute the fuzzy behaviour of the molecule and resulting tunneling current fluctuations to the motion of the molecule in a double-well potential and propose two most likely kinds of the motion which most closely agree with the obtained data.

Under de senaste 10 åren har ett projekt utvecklats på Europeiskt Supplemental Instruction (SI) centrum i Lund som innebär att införa SI-verksamhet i gymnasieskolan. Då SI-verksamhet på gymnasieskolenivå är relativt nytt kunskapsområde har det inte hunnits göra så mycket forskning inom ämnet. Det har därför väckts ett intresse hos författaren kring hur SI påverkar elevers möjlighet att utveckla deras problemlösningsförmåga. Syftet med denna studie har varit att studera SI och traditionell undervisning och se hur samtalsutrymmena i de olika undervisningsmetoderna ger utrymme för eleverna att uppfylla de förmågor i ämnet matematik för gymnasieskolan som rör problemlösning. Detta har gjorts genom observationer av SI-pass och traditionella lektioner. Resultatet och slutsatsen visar att eleverna får mer utrymme på SI-passen att träna sig i matematiskt resonemang och diskutera lösningsstrategier. Studien har även visat att läraren spelar en stor roll i hur eleven ges möjlighet att utveckla problemlösningsförmågan, dels genom hur mycket de tillåter eleverna att prata men också genom vilken typ av uppgifter som eleverna ges.

Rechargeable lithium ion batteries (LIBs) have long been used to power not only portable devices, e.g., mobile phones and laptops, but also large scale systems, e.g., electrical grid and electric vehicles. To meet the ever increasing demand for renewable energy storage, tremendous efforts have been devoted to improving the energy/power density of LIBs. Known for its high theoretical capacity (4200 mAh/g), silicon has been considered as one of the most promising negative electrode materials for high-energy-density LIBs. However, diffusion-induced stresses can cause fracture and, consequently, rapid degradation in the electrochemical performance of Si-based negative electrodes. To mitigate the detrimental effects of the large volume change, several strategies have been proposed. This dissertation focuses on two promising approaches to make high performance and durable Si electrodes for high capacity LIBs. First, the effect of polymeric binders on the performance of Si-based electrodes is investigated. By studying two types of polymeric binders, polyvinylidene fluoride (PVDF) and sodium alginate (SA) using peel tests, SEM, XPS, and FTIR, I show that the high cohesive strength at the binder-silicon interface is responsible for the superior cell performance of the Si electrodes with SA as a binder. Hydrogen bonds formed between SA and Si is the main reason for the high cohesive strength since neither PVDF nor SA bonds covalently with Si. Second, the fabrication of high performance Si/polyacrylonitrile (PAN) composite electrode via oxidative pyrolysis is investigated. We show that high performance Si/polyacrylonitrile (PAN) composite negative electrodes can be fabricated by a robust heat treatment in air at a temperature between 250 and 400oC. Using Raman, SEM, XPS, TEM, TGA, and nanoindention, we established that oxidation, dehydration, aromatization, and intermolecular crosslinking take place in PAN during the heat treatment, resulting in a stable cyclized structure which functions as both a binder and a conductive agent in the Si/PAN composite electrodes. With a Si mass loading of 1 mg/cm2, a discharge capacity of ~1600 mAh/g at the 100th cycle is observed in the 400oC treated Si/PAN composite electrode when cycled at a rate of C/3. These studies on the structure-property-performance relations of Si based negative electrode may benefit the LIB community by providing (1) a guide for the design and optimization of binder materials for Si electrodes and (2) a facile method of synthesizing Si-based composite negative electrodes that can potentially be applied to other Si/polymer systems for further increasing the power/energy density and lower the cost of LIBs for electric vehicle applications and beyond.

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