Le travail de thèse est préliminaire à une étude consacrée à l'élaboration et la validation d'une méthodologie permettant de prédire l'avancement des réactions de Maillard lors de la cuisson de la génoise. L'objectif du travail est de développer des outils expérimentaux pour suivre des marqueurs réactionnels et des variables de procédés de manière synchrone. Dans un premier temps, nous avons donc proposé un schéma réactionnel à la lumière de la connaissance expérimentale des composés volatils générés au cours de la cuisson de la génoise et des données de la littérature. Ensuite, un four pilote a été spécialement conçu et instrumenté. Deux dispositifs d'échantillonnage non perturbateur pour prélever les génoises et les vapeurs de cuisson en continu (au cours de la cuisson) ont été développés et validés. Le dispositif d'échantillonnage des vapeurs de cuisson est un système qui assure le piégeage des composés volatils libérés au cours de la cuisson de la génoise. Aprés avoir stabilisé l'environnement thermique de l'extraction et optimisé la méthode pour les marqueurs sélectionnés, nous avons examiné la répétabilité, la linéarité et la robustesse de la méthode et capacité d'une telle méthode à quantifier certains composés d'arôme libérés au cours de la cuisson de la génoise. À cet effet, les coefficients de proportionnalité entre les concentrations dans la phase gazeuse et dans la fibre SPME ont été déterminés. Nous nous sommes enfin intéressés à l'acquisition des données cinétiques des marqueurs avec les outils validés afin d'observer le schéma réactionnel sélectionné. Les essais de cuissons ont été menés selon un plan de cuisson à trois températures d'air, 140°C, 170°C et 200°C. La dégradation des réactifs et la génération des produits de réactions semblent être étroitement liés aux variables de procédés étudiées (température, teneur en eau, humidité de l'air). De plus le suivi de l'évolution des précurseurs au cours de la cuisson de la génoise montre que bien que la réaction de Maillard reste prépondérante, d'autres réactions sont impliquées dans leurs dégradations en fin de cuisson, probablement la réaction de caramélisation et l'isomérisation des sucres. / The thesis is a preliminary study on the development and validation of a methodology to predict the progress of Maillard reactions during the baking of sponge cake. The aim of this work is to develop experimental tools to track markers and reaction process variables synchronously. Initially, we proposed a reaction scheme based on experimental knowledge of the volatile compounds generated during sponge cake baking and literature data. Then, a pilot oven was designed and instrumented. Two non-invasive sampling devices to collect the sponge cakes and baking vapors continuously (during baking) have been developed and validated. The volatiles sampling device is a system that ensures the trapping of volatile compounds released during the cake baking. After we have stabilized the thermal environment of the extraction and optimized the method for the selected markers, we examined the repeatability, linearity and robustness of the method and capacity of such a method to quantify some aroma compounds released during the cake baking. Fot this reason, the proportionality coefficients between the concentrations in the gas phase and the SPME fiber were determined. Finally, we were interested in the acquisition of kinetic data markers with validated tools to observe the selected reaction scheme. The baking experiments were conducted using at three air temperatures, 140 ° C, 170 ° C and 200 ° C. The degradation of the reactants and the generation of reaction products appear to be closely related to studied process variables (temperature, moisture, humidity). Also tracking the evolution of precursors during the baking of the sponge cakes shows that although the Maillard reaction is still predominant, other reactions are involved in their degradation after baking, probably the caramelization and the isomerization of sugars reactions.

Cette thèse s’intéresse à la construction des pratiques tutorales dans le cadre d’une formation ouverte et à distance au sein de Campus Numériques français. L’hypothèse centrale de ce travail est que, malgré de nombreuses contraintes, les tuteurs à distance, en grande majorité, poursuivent cette activité. L’auteur commence par mettre en lumière, par le biais d’une trentaine d’ entretiens semi-directifs, les représentations des tuteurs concernant leur activité : quelles ressources et quels liens entrent dans la construction de leurs pratiques. C’est grâce au « modèle-service » quadripolaire que l’analyse s’effectue : quelles influences peuvent avoir le « système », « les pairs », « la personne-à-qui-s’adresse le service » (les étudiants) et « soi » sur la pratique tutorale à la fois individualisée et sociale. Les conclusions de ce travail permettent à l’auteur d’envisager la poursuite de l’activité tutorale comme une réponse à une ou des logique(s) individuelle(s) idiosyncrasique(s) à chacun des tuteurs dans le cadre de la sociologie de l’expérience. / This dissertation addresses the matter of constructing tutorial practices construction in e-learning French campuses. The main hypothesis of this work is that, despite numerous constraints, most cybertutors pursue their tutorial activity.The author starts her research by in highlighting tutors’ representations of their activity through about thirty semi-directed interviews : which resources and links are required in building their practices. Thanks to the four poles “service-model”, the author can analyze the influences of the “system”, “the peers”, “the students” and “oneself” on tutorial practices which are individual and social in nature.These findings lead the author to consider the pursuit of tutorial activity as an answer to individual idiosyncrasic logic(s) for every tutor. This is accomplished through experience sociology.

The main aim of this research project is to extend theories of four-wheel-steering as developed by J. Ackermann to include an individually steered four-wheel steering system for passenger vehicles. Ackermann’s theories, including theories available in this subject area, dwell much on vehicle system dynamics developed from what is called single track model and some call it a bicycle model. In the bicycle model, the front two wheels are bundled together. Similarly, the rear wheels are bundled together. The problem with this is that it assumes two front wheels or two rear wheels to be under the same road, vehicle and operating conditions. The reality on the ground and experiments that are conducted are to the contrary. Therefore this study discusses vehicle disturbance rejection through robust decoupling of yaw and lateral motions of the passenger vehicle. A mathematical model was developed and simulated using Matlab R2008b. The model was developed in such a way that conditions can be easily changed and simulated. The model responded well to variations in road and vehicle conditions. Focus was in the ability of the vehicle to reject external disturbances. To generate yaw moment during braking, the brake on the left front wheel was disconnected. This was done because lateral wind generators, as used by Ackermann, were not available. The results from both simulations and experiments show disturbance rejection in the steady state. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Mechanical and Aeronautical Engineering / unrestricted

The connection of high penetrations of new low carbon technologies such as PV and electric vehicles onto the distribution network is expected to cause power quality problems and the thermal capacity of feeder cables may be exceeded. Replacement of existing infrastructure is costly and so feeder cables are likely to be operated close to their hosting capacity. Network operators therefore require accurate simulation models so that new connection requests are not unnecessarily constrained. This work has reviewed recent studies and found a wide range of assumptions and approximations that are used in network models. A number of these have been investigated further, focussing on methods to specify the impedances of the cable, the impacts of harmonics, the time resolution used to model demand and generation, and assumptions regarding the connectivity of the neutral and ground conductors. The calculation of cable impedances is key to the accuracy of network models but only limited data is available from design standards or manufacturers. Several techniques have been compared in this work to provide guidance on the level of detail that should be included in the impedance model. Network modelling results with accurate impedances are shown to differ from those using published data. The demand data time resolution has been shown to affect estimates of copper losses in network cables. Using analytical methods and simulations, the relationship between errors in the loss estimates and the time resolution has been demonstrated and a method proposed such that the accuracy of loss estimates can be improved. For networks with grounded neutral conductors, accurate modelling requires the resistance of grounding electrodes to be taken into account. Existing methods either make approximations to the equivalent circuit or suffer from convergence problems. A new method has been proposed which resolves these difficulties and allows realistic scenarios with both grounded and ungrounded nodes to be modelled. In addition to the development of models, the voltages and currents in a section of LV feeder cable have been measured. The results provide a validation of the impedance calculations and also highlight practical difficulties associated with comparing simulation models with real measurement results.

Due to its inherent stability and compactness, integrated optics can allow for experimental complexity not currently achievable with bulk optics. This opens up the possibility for large-scale quantum technological applications, such as quantum communication networks and quantum information processing. Quantum information processing relies on efficient sources of entangled photon pairs. Most demonstrations in integrated photonics so far have featured the on-chip manipulation of photon states using a free-space bulk-optic source of photons. This has the drawback of introducing loss due to the spatial mode mismatch between waveguide modes of the chip and modes of the produced photons. In this way, loss limits the number of photons that are simultaneously carried in the integrated optical device, and thus limits the number of qubits. One way to avoid this loss is to generate the photons in another waveguide device. This can be done through, for example, spontaneous four-wave mixing (SFWM). In this third-order nonlinear process, two pump photons spontaneously scatter off each other to create two photons of two new frequencies, satisfying momentum and energy conservation. This has been studied in birefringent optical fibers and photonic crystal fibers. In this work, we investigate the SFWM generation of photons in a waveguide coupler comprised of two touching tapered optical fibers, which we call a microcoupler. The two silica fibers are kept in contact and tapered to be 1 micron in diameter in the 10 cm long uniform interaction region. This device has three main advantages over a standard telecom 2x2 fiber coupler. 1) The small mode area enhances the photon generation rate; 2) The microcoupler supports four modes which is the minimum number required for two-photon entanglement. So in principle the device should be able to produce polarization-entangled photon pairs; 3) The strong waveguide-waveguide coupling and waveguide dispersion (due to the tapering) forces the photons to be far in wavelength from the background light around the pump. We present the 28 allowed phasematching processes for the microcoupler, as well as predict the frequencies of the generated photons. We report the first experimental observation of photon pairs produced via SFWM in a microcoupler. We also analyze the polarization state of the observed photons to figure out which phasematching processes are responsible for generating the photons. We expect to observe more photon pairs in future devices, with the ultimate goal being the generation of polarization-entangled photon pairs for integrated optics.

The aim of the thesis is to propose a change of strategy of corporate social responsibility at PricewaterhouseCoopers. The first partial goal is to analyse the current PwC employees' attitude to current activities of social responsibility at PwC. The online questionnaire is used to analyse employees 'opinions and ideas. Subsequently, the questionnaires will be analysed using statistical methods. The second sub-objective is to compare these activities with other companies of Big Four (Deloitte, EY, KPMG). The third sub-objective is to evaluate the effect of parent companies for socially responsible behaviour in the field of consulting. Finally, the changes of the corporate social responsibility strategy at PwC will be proposed. Moreover, thanks to my collaboration with CSR coordinator at PwC, the proposed changes will be followed by implementation at PwC.

Adequate and affordable housing for low-income residents is essential for the well being of the community. In the City of Vancouver, the majority of available low-income housing is located in the inner city and, in particular, the area around the Downtown Eastside neighborhood. The continued loss of units due to redevelopment and conversion is a serious concern in relation to the lagging replacement of units. This study explores the relationship between inner city gentrification and social housing provision. It looks at current gentrification trends in Canadian inner cities and uses the case example of the Four Sisters Housing Cooperative in the Downtown Eastside neighborhood to illustrate a possible model for future housing. Gentrification is shown to be a major factor behind the increased pressure for residential development and the conversion of existing units in the inner city. A second contributing factor is the planned redevelopment of large parts of the inner city. Both are considered by-products of the restructuring of the urban economy from manufacturing to the service industries, which increases competition for and around the central business district. The study provides a cursory examination of current theory on gentrification with an emphasis on the impact on social housing provision. A number of factors are shown to influence the demand for residential accommodation in Vancouver’s inner city. These are: -the favourable central location of the inner city relative to suburban locations; -the shift of the economy to the service sector, which has resulted in the growth of residential opportunities to capture the growing market of downtown workers; -the increase in tertiary and quaternary employment; -new consumer preferences which value the inner city lifestyle; -significant demographic changes related to the age, household size and composition, employment profile, and income of inner-city population; -the continued economic dominance of the downtown. Research carried out in various Canadian cities indicates that gentrification is becoming more complex, often moderate or gradual, and potentially chaotic. The observed encroachment of development activity, growth in the number of families, and the prognosis for new residents with a higher socioeconomic status, is a concern in terms of the future ability to develop housing for local residents and establish policy for the protection of existing private housing. The study shows that the Four Sisters Cooperative has achieved both practical and political goals by providing secure, long-term accommodation for Downtown Eastside residents, providing further economic stability in the area, and adding to the needed stock of family housing. Through its income base, the Four Sisters also caters to a rising demand for low-end market housing in the inner city. The new advocacy for family accommodation in the inner city on the part of the Vancouver Planning Department is evidence of the success of the project. The findings suggest that, as the Canadian inner city becomes more economically and socially diverse, initiatives like the Four Sisters are uniquely suited to respond effectively to the future need for long-term, low-income accommodation. However, the Four Sisters model is unlikely to be readily replicated in the difficult economic times ahead, particularly given the deep level of subsidy that it requires and the current fiscal constraints which all levels of government are under. This implies that future housing solutions must be formulated through government leadership and in cooperation with the community, all levels of government, the non-profit sector, and the private sector. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate

M.A. (English) / Please refer to full text to view abstract

Studien syftar till att bidra med kunskap om, i vilken utsträckning läromedel i matematik föreslår laborativa aktiviteter. Forskning visar att det är gynnsamt för elever att arbeta laborativt. Metoden som valdes är en kvalitativ innehållsanalys. Det skapades ett analysschema med hjälp av tidigare forskning och läroplanen från 2011, specifikt för den här studien. Utifrån analysschemat analyserades tre olika läromedel för årskurs fyra i matematik. Studien har använt det sociokulturella perspektivet för att skapa förståelse för laborativa aktiviteter. En laborativ aktivitet genomförs antingen med ett laborerande arbetssätt eller ett konkretiserande arbetssätt. För att analysera och tolka resultaten har tidigare forskning och variationsteorin används.  Resultatet visar att laborativa aktiviteter främst förekommer inom kunskapsområde Taluppfattning och tals användning. Det visar även att det är laborerande arbetssätt som används mer än konkretiserande arbetssätt vid de laborativa aktiviteterna.  Pedagogiska material föreslås till störst andel av de laborativa aktiviteterna. Läromedlen i studien föreslår laborativa aktiviteter i olika stor utsträckning. Ett läromedel som föreslår få laborativa aktiviteter kräver mer av läraren. Det betyder att läraren själv får hitta och producera laborativa aktiviteter. Läromedel som föreslår många laborativa aktiviteter skapar förutsättningar för lärare att arbeta laborativt. Studien har bidragit till mer kunskap om laborativa aktiviteter i läromedel. / This study aims to contribute knowledge of what extent teaching materials in mathematics suggest laboratory activities. The teaching materials in the study suggest laboratory activities to various extent. The method chosen is a qualitative content analysis. An analysis scheme was created using previous research and curriculum from 2011, specifically for this study. Based on the analysis scheme, three different teaching materials for grade four, mathematics were analyzed. The study has used the socio-cultural perspective to create an understanding of laboratory activities. A laboratory activity is carried out either with a laboratory method or a concretized method. In order to analyze and interpret the results, previous research and the theory of variation have been used. The result shows that laboratory activities mainly occur in the knowledge areas of numerical understanding and the use of numbers. It also shows that laboratory methods are used more often than concretized methods in the laboratory activities. Educational materials are suggested for most laboratory activities. Research shows that it is beneficial for students to work with laboratory activities. A teaching material that suggests few laboratory activities requires more from the teacher. This means that teachers themselves have to find and produce laboratory activities. Teaching materials that suggest many laboratory activities creates conditions for teachers to work laboratory. This study has contributed to more knowledge about laboratory activities in teaching materials.

Les liaisons opto-hyperfréquences sont appelées à jouer un rôle important dans les futurs systèmes micro-ondes. Elles permettent par exemple de transporter des signaux radars ou des oscillateurs locaux sur porteuse optique sur de longues distances. Elles permettent également de réaliser un certain nombre de fonctions comme des déphasages, l’introduction de retards vrais sur de larges bandes passantes, le filtrage reconfigurable des signaux, ou même des fonctions plus complexes comme de l’analyse spectrale ou de la corrélation de signaux hyperfréquences. Comme tous les systèmes opto-hyper, elles souffrent de pertes dues soit à la conversion opto-hyper, soit tout simplement à la propagation. Les amplificateurs classiques, par exemple à fibre dopée erbium, à semi-conducteur, ou à effet Raman dans les fibres, ne permettent pas de compenser ces pertes sans dégrader le rapport signal sur bruit. L’objectif de la thèse est l’étude et la réalisation expérimentale d’un amplificateur optique sensible à la phase basé sur des fibres hautement non linéaires (HNLF) pour amplifier des signaux analogiques sans ajouter du bruit. La majeure partie de ce travail de thèse a été consacrée à la mise en œuvre d’une expérience qui porte sur l’amplification sensible à la phase avec une seule pompe. Notre étude a également porté sur l’étude des performances de cet amplificateur en termes de linéarité et de bruit. La linéarité de l’amplificateur a été testée en comparant les produits d’intermodulation d’ordre 3 (IMD3) lorsque le PSA est activé et le PSA est désactivé. Nous avons montré à partir de ces mesures que l’introduction de l’amplificateur sensible à la phase dans la liaison n’a pas dégradé la dynamique libre de parasite (SFDR). De plus, nous avons étudié les performances de notre amplificateur sensible à la phase en termes de bruit en effectuant des mesures de son facteur de bruit (NF). En effet, nous avons mesuré un facteur de bruit de -2.07 dB dans le cas où l’on ne détecte que le signal, tandis qu’un facteur de bruit de 0.2 dB est obtenu lors de la détection de l’ensemble « signal et idler ». / Microwave photonic links are expected to play an important role in future RF systems. Based on low loss optical fibers, analog photonic links (APLs) have become the heart of the emerging field of microwave photonics, in which various functionalities are explored such as the generation and distribution of radar signals and local oscillators, phase shifting, reconfigurable true time delays, or even more complex functions such as spectrum analysis or correlation of RF signals. Unavoidably, microwave photonics systems undergo losses due either to microwave-to-optical conversion or to propagation. Classical amplifiers based on erbium doped fibers, semiconductor amplification, or Raman scattering in fibers, do not allow to compensate for these losses without degrading the signal-to-noise ratio. The aim of this thesis is to address this issue and to theoretically study and experimentally an optical phase-sensitive amplifier based on highly nonlinear fiber (HNLF) in order to amplify an analog signals without adding noise. We experimentally investigate the linearity of a phase sensitive amplifier based on nonlinear optical fiber in the context of microwave photonics. The linearity of the PSA amplifier is assessed by performing third order intermodulation distortion products (IMD3) measurements using two RF tones. The results show that the PSA is, in the explored domain, perfectly linear for the RF modulation, leading to amplification without any increase of distortion, thus proving the compatibility with future microwave photonics applications. In addition, we study the performance of our PSA in terms of noise by taking measurements of the noise figure (NF). Indeed, we measure a noise factor of -2.07 dB in the case where when we detect only the signal, while a 0.2 dB noise factor is obtained when both "signal and idler" are detected.