This thesis is a literature study on how existing research on embodied tool use may support the use of the use of the computer mouse within three dimensional environments, followed by an analysis of a typical scenario in the use of three dimensional environment. Problems with interaction in this domain are well known to designers of 3d programs but not well understood, which results in programs in which mouse controllers are used to control three dimensional objects being more difficult to learn and less efficient to use than would be possible if the interaction was better understood. The problems are often identified by their symptoms, such as the drag-threshold problem, picking problem, and the object rotation/viewpoint management problem, but this thesis will explore what the cause of those problems is, and identifies them all as a single cognitive problem which is found to be caused by a rift between the functioning of the two dimensional tool in use (the mouse and cursor) and the simulated three dimensional environment with which the cursor is interacting. Analyses are performed on a scenario, and result in a pinpointing of the problem and possible solutions to the interaction part of the problem (with design guidelines emerging), as well as finding the possibility that the cognitive roots of the problem result from an incompatibility between body-schema frames of reference for movement between the two dimensional parts of the action and the three dimensional part of the action.

The aim of the study was to investigate how four pupils in sixth grade use language when writing narrative texts, examined in relation to the typical structure and linguistic features of a narrative text. Another aim was to explore the similarities and differences between texts which received an A or B grade and texts with a D or E grade. The pupils’ texts are analysed from a systemic-functional perspective on language and on the basis of the typical structure and language of a narrative text, with the focus on expressions of time, processes, descriptions and nominal groups (cf. Johansson & Sandell Ring 2012). The main finding is that the four pupils in their texts master the normal structure of a narrative text and that their texts have expressions of time, processes, descriptions and nominal groups, but they differ in extent and scope. The greatest differences between the narratives in the different grading categories are found in the introductions to the texts, the way of marking dialogue in the structure, and how the pupils use processes, circumstances and nominal groups to achieve descriptions. The text that received an E grade differs from the other texts that were graded as A, B and D, in that the writer has the shortest introduction to the text; the introductions to the other texts are relatively long. The E-graded text also differs from the other texts in the way it marks dialogue. That pupil uses quotation marks to indicate where dialogues occur, whereas the texts with A, B and D grades use a quotation dash to mark speech. All the pupils’ texts contain expressions of time. The texts also include several kinds of processes, except for the text that received a B grade, where there were no mental processes. The texts graded as A, B and D use expanded nominal groups and also various processes and circumstances to create descriptions. The text that received an E grade is the one that uses most expanded nominal groups for descriptive purposes.

Ce manuscrit présente les travaux de thèse réalisés dans le cadre d’une convention CIFRE entre Renault Trucks et le LMFA. Une stratégie de contrôle d’écoulement, associant un volet déflecteur et des actionneurs de type jets pulsés et synthétiques, est étudiée expérimentalement en vue de réduire la traînée aérodynamique de corps non profilés à culot droit. Une première approche consiste à étudier l’influence de cette stratégie sur une maquette bidimensionnelle. Des mesures de vitesse dans le sillage proche par TR-PIV et par anémométrie à fil chaud démontrent qu’une certaine gamme de fréquence d’actionnement permet à l’écoulement de recoller sur le volet et de diminuer les fluctuations de vitesse dans la zone de recirculation, ce qui engendre une augmentation de la pression au culot. Une analyse par moyenne de phase et la détermination de corrélations spatio-temporelles permettent d’identifier les perturbations induites par le contrôle conduisant à ces modifications de l’écoulement. Un système de jets synthétiques est ensuite intégré à une maquette simplifiée de véhicule poids lourd à l’échelle 1/8e, dont le sillage est représentatif des remorques réelles. Des gains en traînée significatifs sont obtenus et sont associés aux mêmes phénomènes aérodynamiques que pour la maquette bidimensionnelle. Enfin, une étude paramétrique montre la robustesse du contrôle aux caractéristiques de la couche limite incidente aux jets et à la longueur du volet déflecteur. / This document presents the research work realized in the scope of a PhD thesis with Renault Trucks and the LMFA. A flow control strategy, combining an inclined flap with pulsed or synthetic jets, is experimentally studied to reduce the aerodynamic drag of square-back bluff bodies. A first approach consists in studying the effect of this strategy on the flow behind a twodimensional model. The near-wake flow is characterized by the use of velocity measurements obtained by Time-Resolved Particles Image Velocimetry and hot-wire Anemometry. These measurements show that the increase in rear base pressure, obtained in a specific range of actuation frequencies, is associated with the reattachment of the flow on the flap and with a decrease in velocity fluctuations within the recirculation area. A phase average analysis and the determination of space-time correlations allow identifying the aerodynamic disturbances induced by the control system and leading to these modifications of the wake flow. A synthetic jet system is integrated to a 1 :8 scale simplified truck model, with a wake flow similar to this of real trailers. Significant drag reductions are obtained using active control and are associated with the same flow phenomena as these observed in the two-dimensional model study. Eventually, a parametric study is performed and shows the robustness of the flow control strategy to the characteristics of the boundary layer developing on the model roof and to the flap length.

Motivée par les contraintes économiques et les exigences environnementales, l'industrie du transport tente de réduire ses dépenses énergétiques. Elle concentre notamment ses efforts sur la traînée de frottement. Bien que d'origine visqueuse, celle-ci est fortement amplifiée par les mouvements turbulents. La capacité à manipuler les fluctuations turbulentes, complexes et chaotiques, offre alors des perspectives de gain énergétique substantiel, mais nécessite une bonne compréhension des phénomènes physiques. Parmi les stratégies de contrôle les plus prometteuses, l'utilisation de revêtements rainurés, nommés riblets, est étudiée dans ce mémoire. Bien que leur capacité de réduction de frottement soit connue depuis plusieurs décennies, les mécanismes par lesquels ils interagissent avec la turbulence restent à préciser. À ces fins, une méthode pour leur simulation numérique est mise au point. En redéfinissant la position de l'origine virtuelle, c'est-à-dire de la paroi plane équivalente, une forte similitude est établie entre les écoulements contrôlé et canonique. D'un point de vue applicatif, cela permet notamment de quantifier les performances de réduction de traînée atteignables à haut nombre de Reynolds. Enfin, le potentiel a priori prometteur des riblets tridimensionnels est exploré. En s'appuyant sur les rares résultats précurseurs de la littérature, il s'agit de proposer une géométrie industriellement réalisable optimale en termes de réduction de traînée. Pour chacune des géométries novatrices testées, les simulations révèlent avec finesse que les éventuels bénéfices sur le frottement sont systématiquement surpassés par l'influence délétère des efforts de pression. / Economical constrains and environmental requirements lead the transportation industry to progress towards energy expenditure reduction. Efforts are especially focused on the skin-friction drag. Friction drag, while due to viscosity, is greatly amplified by turbulent motions. The ability to manipulate the complex and chaotic near-wall turbulent fluctuations thus offers prospects for substantial energy saving, but also requires a solid understanding of the physical phenomena.Among the most promising control strategies, the present manuscript focuses on riblet-covered surfaces. Even though their drag-reducing capability has been observed from decades, the mechanisms by which they interact with the near-wall turbulent motions still need to be clarified. Towards these ends, a numerical method for ensuring their proper simulation is developed. The virtual origin—interpreted as the equivalent flat wall location—is redefined, which highlights a strong similarity between the controlled and the canonical flows. As a practical interest, this similarity enables an improved evaluation of the drag reduction capabilities achievable at high Reynolds numbers.Additionally, the promising potential for three-dimensional riblets is examined. Based on the scattered precursory results of the literature, we intend to come up with a design which demonstrates optimal drag reduction capabilities under the constraint of industrial feasibility. For each of the prospected innovative designs, the numerical simulations accurately reveal that the potential profit on skin-friction is consistently exceeded by the harmful influence of pressure stresses.

Ventilation might seem like a minor consideration, but when properly installed, it can extend the life of the attic and roof structure of residential buildings saving huge dollar amounts in repair costs. The objectives of this study were to measure the wind effect on different kind of vents as the problem is vents are subjected to high wind loads during hurricane events and often fail causing water penetration and damage of interior contents. Wind-induced failure of rooftop vents during a hurricane may result in large openings in the roof that will allow water to penetrate into the building, a puncturing of the roof membrane, again allowing water infiltration, and detached rooftop vents can pose considerable threats as windborne debris. The study found that water infiltration through a vent system is dependent upon the differential pressure as well as the vent mechanism. For vents experiencing higher differential pressures, vent covers can be used during storms to reduce water infiltration. Active controls can also be designed to close the vents automatically as differential pressure increases based on the wind speed and wind angle of attack.

La combustion en boucle chimique (CLC) est un procédé du type oxy-combustion où des particules sont utilisées pour fournir de l'oxygène à la combustion. Des études sont nécessaires pour l'extrapolation et l'optimisation du procédé CLC, fonction des propriétés des particules du groupe B et de la technologie CFB. Les études hydrodynamiques ont été faites dans un riser de 18 m de hauteur. Des profils axiaus de pression, ainsi que les profils radiaux de flux et de quantité de mouvement ont été obtenus. Trois types de particules ont été utilisées ayant un diamètre de Sauter entre 250 et 300 μm et une densité entre 2600 et 3300 kg/ m3. Un impact de la sphéricité des particules sur la perte de charge a été révélé. Dans des conditions identiques, les billes de verre génèrent des pertes de charge d'environ 50% inférieures à celles du sable. Dans la zone d'écoulement développée, la présence du régime cœur-anneau a été détectée. Un modèle hydrodynamique 1D du riser qui est à la fois fondé sur des données expérimentales et sur les équations gaz-solide Euler-Euler, a été développé. Une nouvelle corrélation pour la force de traînée moyennée sur la section est proposée. Une nouvelle corrélation des conditions limite dans la partie inférieure du riser a aussi été établie. Le modèle 1D final est en mesure de prédire la perte de charge du riser pour différentes conditions opératoires et en tenant compte des propriétés des particules, comme la densité, la taille et la forme. Une étude sur la pertinence de l'utilisation du logiciel Barracuda CPFD® pour simuler des particules du groupe B en régime de transport a été réalisée. Il a été montré que le code sous-estime la perte de charge pour le sable / Chemical Looping Combustion (CLC) is an oxy-combustion like process where particles are used to supply oxygen to combustion. Further work is still needed for extrapolation and optimization of the CLC process, concerning properties of Group B particles and CFB technology. Hydrodynamic tests were made on a 18 m tall riser. Axial pressure profiles as well as radial flux profiles and radial momentum quantity profiles were obtained. Three types of Group B particles were used with Sauter mean diameters between 250 and 300 μm and densities between 2600 and 3300 kg/m²s. An important impact of particle sphericity on riser pressure drop has been revealed. At identical conditions, glass beads present about half the pressure drop generated by sand. In the developed region of the riser, the core-annulus regime has been found. A 1D model of the riser, based on experimental results and on the Euler-Euler gas-solid equations, has been developed. Moreover, a new cross section averaged drag force correlation is presented. A new boundary condition on the bottom of the riser has been investigated. The final 1D model is capable of predicted riser pressure drop from the operating conditions and it takes into account particle properties such as density, size and shape. A study on the adequacy of the use of the commercial CFD code Barracuda to simulate risers with Group B particles was made. It was shown that the code under estimates pressure drop along the riser for sand simulations

Cette thèse présente une étude expérimentale et numérique des forces s'exerçant sur un objet en mouvement dans un milieu granulaire. La compréhension précise de ces forces présente en effet d'importants intérêts fondamentaux (rhéologie des milieux granulaires, phénomène de ségrégation) et appliqués (robotique, locomotion animale ...). Expérimentalement, un cylindre horizontal est mis en rotation à faible vitesse dans un bac de billes de verre. Les forces s'exerçant sur cet objet dans la direction du mouvement (forces de traînée) et dans la direction verticale (forces de portance) sont mesurées.Lors du premier demi-tour, avant que le cylindre ne repasse dans son propre sillage, nous mettons en évidence l'existence d'une force de portance élevée sur l'objet (bien qu'il soit symétrique), de l'ordre de 20 fois la poussée d'Archimède du milieu, et indépendante de la profondeur. Des études numériques de dynamique moléculaire (méthode éléments discrets) permettent de comprendre comment cette portance émerge de la modification de l'écoulement granulaire par la présence d'un gradient de pression dans le milieu. Aux temps longs, après plusieurs rotations du cylindre, on observe une chute de la force de traînée, qui devient indépendante de la profondeur. Le milieu se structure sous l'effet des passages répétés du cylindre dans son sillage, ce qui écrante le poids des grains situés au dessus. Enfin, une étude numérique des forces sur une grosse particule en écoulement avec le milieu granulaire est ébauchée, en lien avec le phénomène de ségrégation granulaire. / This thesis presents an experimental and numerical study of the forces experienced by an object moving in granular media. This problem, which is of practical importance in many applications (robots, animal locomotion), is also of fundamental interest (rheology of granular materials, granular segregation). The experiment consists in a horizontal cylinder rotating around the vertical axis in glass beads. Both drag forces and lift forces experienced by the cylinder are measured.During the first half rotation, before the cylinder crosses its own wake, we measure a strong lift force (despite the symmetry of the object), about 20 times the buoyancy of the cylinder, and independent of its depth. Molecular dynamic simulations (Discrete Element Method) shed lights on how this lift force arises from the modification of the grain flow due to the pressure gradient in the medium. After several rotations, when the cylinder goes through its own wake, the drag force drops and becomes independent of depth. The rotation of the cylinder induces a structure in the granular packing, which screens the weight of the grains above it. Finally, a numerical study of forces on a large particle flowing with the granular medium is sketched, in relation with the phenomenon of granular segregation.

La gamme des ondes terahertz (THz) se situe à l'interface des domaines électronique et optique. Malgré un potentiel d'applications élevé, elle souffre d'un manque de dispositifs performants. Dans ce cadre, cette thèse se concentre sur l'étude fondamentale et la réalisation de nouvelles fonctionnalités associées à différentes sources THz, en utilisant la spectroscopie THz dans le domaine temporel (TDS). Cet outil puissant permet de mesurer le profil temporel d'un champ électrique THz et est utilisé pour explorer l'émission THz de lasers à cascade quantique (LCQ) et de graphène.Dans une première partie, la réponse ultrarapide de LCQs est étudiée. Un contrôle de la phase du champ électrique de LCQs THz via la technique "d'injection seeding" est réalisé puis optimisé. Il nous permet de mesurer le profil temporel de l'émission laser. A l'appui de cette expérience et de simulations, une description quantitative de la dynamique du gain est faite. Ces informations sont critiques pour la production d'impulsions courtes. Une modulation rapide du gain de LCQ est ensuite réalisée et conduit à la génération d'impulsions courtes (durée ~ 15 ps) en régime de blocage de modes. Ces études permettent notamment d'envisager les LCQs comme sources puissantes pour la TDS. Dans une seconde partie, nous montrons que le graphène peut émettre un rayonnement THz sous excitation optique par un effet non linéaire d'ordre 2. Cette émission résulte d'un transfert de quantité de mouvement des photons aux électrons du graphène ("photon drag"). Elle permet ainsi d'explorer des propriétés subtiles du graphène, telles que de très faibles différences de comportement entre les électrons et trous photogénérés. / The terahertz (THz) range is a region of the electromagnetic spectrum which lies at the limit between the electronic and optical domain. Currently, THz applications suffer from the lack of sources and detectors. In this context, this thesis focuses on the fundamental study and the development of new functionalities of different THz sources, usingTHz time-domain spectroscopy (TDS) as a base. This powerful tool enables to acquire the temporal profile of a THz electric field and is used to explore the THz emission properties of quantum cascade lasers (QCLs) and graphene.In the first part, the ultrafast response of QCLs is investigated. A phase control of the electric field of THz QCLs via injection seeding is realised and optimised. This enables the measurement of the amplitude and temporal profile of the laser emission. Throughthese experiments and simulations, a quantitative description of the gain dynamics can be accessed. This information is critical for modelocking. Finally, a fast modulation of the gain of QCLs is realized and leads to short pulses generation (15 ps) in a modelocked regime. These studies open the way for using QCLs as powerful sources in TDS.In the second part, THz radiation generation from graphene under optical excitation is demonstrated by a second order non-linear process. The THz emission results from themomentum transfer from the photons to the electrons of graphene (photon drag). As well as broadband THz generation, novel bandstructure properties of graphene can be explored such as the different dynamics between the photogenerated electrons and holes.

Submitted in partial compliance with the requirements for the Masters Degree in Technology: Chiropractic, Durban University of Technology, Durban, South Africa, 2016. / Background In sport, competitive athletes are required to perform to the best of their ability, with some athletes seeking the use of chiropractic treatment to improve performance. For example, hockey players are required to perform at peak physical function whilst executing a drag flick. The action of a drag flick involves a player hunched over low down in front of the ball and the hook of the hockey stick makes contact with the ball, which is then ball is pushed along the ground with the ball moving slightly up the shaft of the stick. The player then performs ‘slinging’ action, which means they ‘flick’ the ball towards the goal posts. The drag flick is an explosive sequential movement involving the player’s pelvis, trunk and upper limbs, requiring the use of the spine to generate the speed of the stick and ball. As a result any decreased spinal movement could reduce performance. Therefore this study attempted to assess the use of spinal manipulative therapy (SMT) in improving the drag flicking performance of hockey players. SMT has been shown to be a safe and effective way of increasing spinal joint mobility Objectives To determine and compare the effect of placebo and spinal manipulative therapy in terms of subjective and objective measurements on drag flicking performance of premier league field hockey players. Methods A comparative, experimental study of forty asymptomatic premier league hockey drag flickers were divided into two groups of twenty each. Group A received SMT of fixated joints of the spine (cervical, thoracic and lumbar) as determined by motion palpation by an experienced qualified chiropractor. Group B received sham manipulation. Pre and post intervention ROM of the spine and drag flicking speed where measured using CROM, Inclinometer, BROM II and Speed TracX Speed Sport Radar. The subject’s perception of a change in drag flicking speed post intervention was also recorded. SPSS version 21 was used to analyse the data. A p value of 0.05 was considered statistically significant. Results Significant differences in ROM were noticed in the inter-group analysis in cervical: extension; LLF; RR PA, thoracic: extension; LLF, RLF, lumbar: extension, LLF, RLF. There was a significant increase in drag flicking speed post SMT, but between the SMT and sham manipulation groups were not significantly different. A significant correlation was seen between subjects’ perception of change in drag flicking speed post intervention and the objective results obtained. Conclusion The immediate effect of SMT on drag flicking performance of hockey players was inconclusive. The outcomes of this study suggests that SMT results in an increase in the average speed of drag flicking, however further larger studies are required to confirm this. / M

Psykopatiska drag kan ge negativa konsekvenser såsom ett antisocialt beteende och låg empati. För att kunna förebygga har forskningen tittat på olika orsaker till att sådana drag utvecklas. Man har bland annat tittat på om otrygga anknytningsstilar har ett samband med psykopatiska drag.   I den här studien deltog 102 personer i ett bekvämlighetsurval. Av de som svarade var 83,3% kvinnor och resten män, de flesta var i åldersgrupperna mellan 41–64 år.   Denna studie visade ett svagt samband mellan otrygg-undvikande anknytningsstil och psykopatiska drag. Andra studier har gjorts med andra urvalsgrupper med problematik såsom psykiatrisk diagnos och kriminalitet. Förmodligen hade resultatet blivit annorlunda med ett annat urval. Tendensen är dock att det finns ett samband mellan otrygg-undvikande anknytningsstil och psykopatiska drag. / Psychopathic traits can have negative consequences such as antisocial behaviour and low empathy. In order to be able to prevent it, research has looked at various reasons why such traits develop. Among other things, they have looked at whether insecure attachment styles have a connection with psychopathic traits.   In this study, 102 people participated in a convenience sample. Of those who responded, 83.3% were women and the rest were men, most were in the age groups between 41–64 years.   This study showed a weak association between insecure-avoidant attachment style and psychopathic traits. Other studies have been done with other sample groups with problems such as psychiatric diagnosis and crime. Probably the result would have been different with a different selection. The tendency, however, is that there is a connection between insecure-avoidant attachment style and psychopathic traits.