À ce jour, nous trouvons de nombreux systèmes requérant l'usage du courant continu dans l'industrie automobile, aéronautique, ferroviaire ou encore dans les panneaux solaires. L'ouverture et la fermeture des circuits alimentés (relais, interrupteurs, etc.) engendrent inévitablement un arc électrique (température ~5000 K). Celui-ci provoque des dégradations plus ou moins importantes aux matériaux de contact, telles que l'érosion, la soudure et l'augmentation de la résistance de contact, pouvant engendrer des dysfonctionnements des appareillages et porter atteinte à la sécurité des personnes qui les utilisent. Face à la demande de puissance électrique des appareils actuels, il est nécessaire d'augmenter la tension ou le courant d'alimentation. La tension actuelle à bord d'une voiture est de 14 VDC, il est envisagé d'augmenter cette tension à 42 VDC afin d'augmenter la puissance pour faire face à la croissance des appareils électroniques et électriques embarqués. L'intérêt d'augmenter la tension, notamment pour des applications liées au milieu automobile, permet de maintenir l'intensité du courant donc conserver un faible diamètre de câble pour une puissance plus importante et permet de ne pas rajouter une masse supplémentaire à la voiture. Cependant, le passage d'une tension de 14 VDC à 42 VDC augmente fortement ces dommages causés aux matériaux de contact par les arcs électriques. Il existe différents moyens permettant la diminution de la durée d'arc, par exemple l'optimisation du dispositif mécanique (modification de la vitesse d'ouverture des contacts, double coupure), ou bien l'utilisation d'aimants permanents qui génèrent un champ magnétique et soufflent l'arc hors de la zone de contact ou encore la modification du matériau de contact (composition chimique, forme). Les matériaux caractérisés dans cette étude allient le soufflage magnétique et l'optimisation de la composition chimique de façon à trouver un bon compromis pour limiter les dégâts causés par les arcs d'ouverture et par les arcs de fermeture. En effet, l'action du champ magnétique permet de diminuer la durée de l'arc d'ouverture (diminution d'un facteur 10) mais n'a malheureusement aucun effet sur l'arc de fermeture. D'où la nécessité de modifier la composition chimique du matériau, notamment par ajout d'oxydes métalliques (SnO2) afin de limiter les dommages de l'arc de fermeture. / Nowadays, we find many systems requiring the use of direct current in the automotive, aerospace, rail, or in solar panels. The opening and closing of the powered circuits (as relays, switches, etc.) inevitably generate an electric arc (temperature ~5000 K). This arc causes more or less significant damage to the contact materials, such as erosion, welding and increase the contact resistance, which can lead to malfunction of the equipment and impair the safety of people who use them. Facing the electric power demand of current devices, it is necessary to increase the voltage or the supply current. Currently, the voltage on board a car is 14VDC, it is planned to increase this to 42VDC voltage, to increase the power to deal with the increase of embedded electronics and electrical appliances. The interest to increase the voltage, especially for applications related to the automotive environment, keeps the current intensity therefore maintain a low cable diameter for greater power and allows not to add an additional weight to the car. However, the passage of a voltage of 14VDC to 42VDC greatly increases the damage caused to contact materials by electric arcs. There are different ways to decrease the arc duration, e.g. optimizing the mechanical device (change in opening speed of the contacts, double break), or the use of permanent magnets that generate a magnetic field and blow the arc out of the contact area, or changing the contact material (chemical composition, shape). The materials characterized in this study combine magnetic blowing and optimizing the chemical composition in order to find a good compromise to limit the damage caused by break and make arcs. Indeed, the action of the magnetic field can reduce the duration of the break arc (decrease by a factor 10) but unfortunately has no effect on the make arc. Hence, the need to modify the chemical composition of the material, including adding metal oxide (SnO2) to limit the make arcs damages.

L’introduction des systèmes électriques notamment des dispositifs d’électronique de puissance « embarqués » dans le domaine de transport aérien, requiert une forte compacité et une forte intégration des systèmes de conversions électriques ainsi des fonctionnalités électroniques a des hautes t ambiantes dépassant les 200°C.Mais pour répondre à ces besoins, le silicium a atteint ses limites d'où le recours à des nouveaux matériaux semi-conducteurs comme ceux à grand gap.Dans le cadre de ses recherches, Thales, en collaboration avec le laboratoire SATIE , mènent des investigations sur les performances des semi-conducteurs en technologie sic pour développer des convertisseurs aéronautiques de nouvelle génération.Ces travaux de thèse s'inscrivent dans le cadre d'une étude des potentialités des premiers composants SiC disponibles sur le marché. Cette étude permet de comparer les principales performances de ces dispositifs ainsi que les contraintes spécifiques induites lors de leur intégration dans les convertisseurs aéronautiques. / The potential of wide band gap transistors based on silicon carbide are remarkable and open new prospects for improvement (high efficiency, high breakdown voltage, high switching frequency and high operating temperature ...). This leads to volume and weight reduction for future converters. In order to improve new generation of power converters for future needs, Thales, in cooperation with SATIE and LTN IFSTTAR laboratories, performs investigations on the performances, advantages and disadvantages of SiC technology semiconductors. This comparative study will assess the strengths and weaknesses as well as the stresses induced during integration into aircraft converters of commercially available devices.

Curcuminoids have strong anticancer activities but have low bioavailability. The highest rate of cancer deaths comes from lung tumours; therefore, inhaled curcuminoids could treat lung cancer locally. To date, there are no nebulised formulations of curcuminoids, and there are no inhalable curcuminoids particles without excipients using air jet mill and sonocrystallisation methods for DPI formulations. It is the first time; the aerodynamic parameters of curcumin, demethoxycurcumin and bisdemethoxycurcumin were measured individually using NGI. The size, shape, free surface energy, and the crystal polymorphism of the produced inhalable curcuminoid particles were characterised using laser diffraction, SEM, IGC, DSC and XRPD, respectively. Several DPI formulations with a variable particle size of curcuminoids were prepared in two drug-carrier ratios (1:9 and 1:67.5). The best performance of the DPI formulations of the sonocrystallised particles, which exist in crystal structure form1, were obtained from ethanol- heptane, as illustrated FPF 43.4%, 43.6% and 43.4% with MMAD of 3.6µm, 3.5µm and 3.4µm, whereas the best DPI formulation of the air jet milled particles was presented FPF 38.0%, 38.9%, and 39.5% with MMAD of 3.6µm, 3.4µm and 3.2µm for curcumin, demethoxycurcumin and bisdemethoxycurcumin, respectively. Nebulised curcuminoids using nanoemulsion and microsuspension formulations were prepared. The physical properties, such as osmolality, pH and the viscosity of the aerosolised nanoemulsion and the microsuspension formulations were determined. The FPF% and MMAD of nebulised nanoemulsion ranged from 44% to 50% and from 4.5µm to 5.5µm respectively. In contrast, the FPF% of microsuspension ranged from 26% to 40% and the MMAD from 5.8µm to 7.05µm. A HPLC method was developed and validated in order to be used in the determination of curcuminoids from an aqueous solution.

No description available.

Ce travail de thèse consiste en l’élaboration d’une méthodologie d’étude de monuments historiques, appliquée au château de Chambord. Il s’agit de mettre en place le carnet de santé de l’édifice, et de le compléter par une expérimentation en laboratoire, afin de réaliser un diagnostic d’altération.Les archives historiques concernant le château ont été rassemblées et analysées pour concevoir des cartographies de dates de pose et de nature des pierres. L’examen in situ des façades a ensuite conduit à réaliser des cartographies d’altération. La synthèse des informations concernant le passé et le présent du monument a permis d’établir une liste des principaux facteurs environnementaux associés aux altérations, de même que la chronologie de leur développement, pour ainsi aboutir à une première estimation des cinétiques de progression.C’est la desquamation en plaques, détérioration courante du tuffeau, à la fois la plus dommageable et la plus complexe, qui a été ciblée pour le diagnostic d’altération. Les analyses physico-chimiques réalisées sur des prélèvements in situ ont conduit à l’identification systématique du gypse dans les fissures des desquamations. Des simulations expérimentales ont été mises en place pour appréhender le rôle du gypse, son mode de transport et son origine. La pollution atmosphérique mettant en oeuvre du SO2 gazeux reproduit bien la distribution du gypse telle que mesurée dans les desquamations en plaques observées au château de Chambord. Un mécanisme incluant ce phénomène a été proposé, pour expliquer le développement de cette altération, et qui pourrait être à la base des prévisions de l’évolution des altérations, afin d’envisager le futur du monument. / This thesis is dedicated to the establishment of a methodology to study the built cultural heritage, applied to the castle of Chambord. It consists in realizing the health record of the monument, and completing it by an experimental sequence in laboratory, in order to provide a diagnosis of the state of degradation.Historical archives about the castle were gathered and analysed to obtain mappings of dating and nature of stone. By mean of in situ observations, a mapping of degradation has been added. A synthesis of the information concerning the past and the present of the monument allowed establishing a list of the main factors associated to degradations and to a chronology of development of these degradations, so as to estimate their kinetics.Spalling, which is the most damaging and complex usual degradation, has been chosen as case of study for the diagnosis of degradation. The physic-chemical characterisations made on in situ coring lead to systematically found gypsum in spalling’s cracks. Various artificial ageing tests have been performed to enlighten the role of gypsum, its transport mode, and its origin. Atmospheric pollution including gaseous SO2 reproduces well the distribution of gypsum observed in spalling at Chambord. A global mechanism taking into account this phenomenon has been proposed to clarify the development of this degradation.

The Asymmetric Spacer layer Tunnel (ASPAT) diode is a new diode invented in the early 90s as an alternative to the Schottky barrier diode (SBD) technology for microwave detector applications due to its highly stable temperature characteristics. The ASPAT features a strong non-linear I-V characteristic as a result of tunnelling through a thin barrier, which enables RF detection at zero bias from microwaves up to submillimetre wave frequencies. In this work, two heavily doped GaAs contact layer on top and bottom layers adjacent to lightly doped GaAs intermediate layers, enclose undoped GaAs spacers with different lengths sandwiching an undoped AlAs layer that acts as a tunnel barrier. The ultimate ambition of this work was to develop a MMIC detector as well as a frequency source based on optimized ASPAT diodes for millimetre wave (100GHz) applications. The effect of material parameter and dimensions on the ASPAT source performances was described using an empirical model for the first time. Since this is a new device, keys challenges in this work were to improve DC and RF characteristic as well as to develop a repeatable, reproducible, and ultimately manufacturable fabrication process flow. This was investigated using two approaches namely air-bridge and dielectric-bridge fabrication process flows. Through this work, it was found that the GaAs/AlAs heterostructures ASPAT diode are more amenable to the dielectric-bridge technique as large-scale fabrication of mesa area up to 4×4Âμm2 with device yields exceeding 80% routinely produced. The fabrication of the ASPAT using i-line optical lithography which has the capability to reduce emitter area to 4×4Âμm2 to lower down the device capacitance for millimetre wave application has been made feasible in this work. The former challenge was extensively studied through materials and structural characterisations by a SILVACO physical modelling and confirmed by comparison with experimental data. The I-V characteristic of the fabricated ASPAT demonstrated outstanding scalability, demonstrating robust processing. A fair comparison has been made between ASPAT and SBD fabricated in-house; indicating ASPAT is extremely stable to the temperature. The RF characterisations were carried out with the aid of Keysight ADS software. The DC characteristic from fabricated GaAs/AlAs ASPAT diodes were absorbed into an ADS simulation tool and utilized to demonstrate the performance of MMIC 100GHz detector as well as 20GHz/40GHz signal generators. Zero bias ASPAT with mesa area of 4×4Âμm2 with video resistance of 90KΩ, junction capacitance of 23fF and curvature coefficient of 23V-1 has demonstrated detector voltage sensitivity above 2000V/W, while the signal source conversion loss and conversion efficiency are 28dB and 0.3% respectively. An estimate noise equivalent power (NEP) for this particular device is 18.8pW/Hz1/2.

In Sweden, during the 1920s, the past played a definite part in the folklore research. The folklore scholars argued for collecting the cultural memories (folkminnen) of “the people”, as they were understood to disappear due to a threat from the modern civilization, which was thought to spread across the countryside at an ever-accelerating pace. This study shows that the past is constructed through discourse – not as a predefined object but rather as a dynamic process of temporal constructions. This study analyses the construction of the past in folklore research in Sweden during the 1920s. Two methodological tools have been primarily used to help unfold the process in which the past is constructed. First, by discourses of the past (förflutenhetsdiskurser) which is how, in my case the scholars, relate to the past by various verbal practices. Secondly, by identifying binary characterizations. In this study, the construction of the past, in folklore research, has been shown through three main themes. First, by understanding the importance of collecting the cultural memories of “the people” as an urgent project – due to their inevitable disappearing – but also as a duty towards the people of the past and as a duty towards future generations. Secondly, by identifying three different dichotomies which all functioned as part of the process of the construction of the past. Thirdly, by analyzing “the people” as a category that best is described as a compound of both culture and human.

Text in English / The study focused on the characterisation and management of non-formal solid waste disposal sites in Harare, the capital city of the Republic of Zimbabwe. In many developing countries, increasing urbanisation surpasses the development of urban infrastructure and this has led to the proliferation of informal settlements, illegal dumping sites and uncontrolled vending in cities like Harare. The researcher investigated the prevalence of non-formal dumping sites in Harare, including the composition, locational attributes and internal linkages of solid waste. Practices regarding the management of non-formal solid waste disposal sites were examined and areas of good practice and conformity to international standards were complemented while recommendations and suggestions were made on areas that were found wanting. An integrated management system was recommended for the sustainable management of solid waste. To support this recommendation, management window of responsibilities (EMWR) model was created so that the Harare City Council can enhance stakeholder participation. The research results show that most residents used non-conventional ways to store waste, like mealie-meal bags and sacks, and this posed a danger to human health. It also emerged that the city of Harare has not updated some of its by-laws, some of which were enacted about 33 years ago while others remained drafts for decades. This made it difficult for the city to effectively implement them. / Environmental Sciences / M.Sc. (Environmental Management)

Ces travaux de thèse concernent l'analyse de la robustesse (stabilité et performance) de systèmes linéaires incertains de grande dimension avec une structure hiérarchique. Ces systèmes sont obtenus en interconnectant plusieurs sous-systèmes incertains à travers une topologie hiérarchique. L'analyse de la robustesse de ces systèmes est un problème à deux aspects : la robustesse et la grande dimension. La résolution efficace de ce problème en utilisant les approches usuelles est difficile, voire impossible, à cause de la complexité et de la grande taille du problème d'optimisation associé. La conséquence de cette complexité est une augmentation importante du temps de calcul nécessaire pour résoudre ce problème d'optimisation. Afin de réduire ce temps de calcul, les travaux existants ne considèrent que des classes particulières de systèmes linéaires incertains de grande dimension. De plus, la structure hiérarchique de ces systèmes n'est pas prise en compte, ce qui montre, de notre point de vue, les limitations de ces résultats. Notre objectif est d'exploiter la structure hiérarchique de ces systèmes afin de ramener la résolution du problème d'analyse de grande taille à la résolution d'un ensemble de problèmes d'analyse de faible taille, ce qui aura comme conséquence une diminution du temps de calcul. De plus, un autre avantage de cette approche est la possibilité de résoudre ces problèmes en même temps en utilisant le calcul parallèle. Afin de prendre en compte la structure hiérarchique du système incertain de grande dimension, nous modélisons ce dernier comme l'interconnexion de plusieurs sous-systèmes incertains qui sont eux-mêmes l'interconnexion d'autres sous-systèmes incertains, etc.. Cette technique récursive de modélisation est faite sur plusieurs niveaux hiérarchiques. Afin de réduire la complexité de la représentation des systèmes incertains, nous construisons une base de propriétés de dissipativité pour chaque sous-système incertain de chaque niveau hiérarchique. Cette base contient plusieurs éléments qui caractérisent des informations utiles sur le comportement de systèmes incertains. Des exemples de telles caractérisations sont : la caractérisation de la phase incertaine, la caractérisation du gain incertain, etc.. L'obtention de chaque élément est relaxée comme un problème d'optimisation convexe ou quasi-convexe sous contraintes LMI. L'analyse de la robustesse de systèmes incertains de grande dimension est ensuite faite de façon hiérarchique en propageant ces bases de propriétés de dissipativité d'un niveau hiérarchique à un autre. Nous proposons deux algorithmes d'analyse hiérarchique qui permettent de réduire le temps de calcul nécessaire pour analyser la robustesse de ces systèmes. Un avantage important de notre approche est la possibilité d'exécuter des parties de ces algorithmes de façon parallèle à chaque niveau hiérarchique ce qui diminuera de façon importante ce temps de calcul. Pour finir et dans le même contexte de système de grande dimension, nous nous intéressons à l'analyse de la performance dans les réseaux électriques et plus particulièrement «l'analyse du flux de puissances incertaines dans les réseaux électriques de distribution». Les sources d'énergies renouvelables comme les éoliennes et les panneaux solaires sont influencées par plusieurs facteurs : le vent, l'ensoleillement, etc.. Les puissances générées par ces sources sont alors intermittentes, variables et difficiles à prévoir. L'intégration de telles sources de puissance dans les réseaux électriques influencera les performances en introduisant des incertitudes sur les différentes tensions du réseau. L'analyse de l'impact des incertitudes de puissances sur les tensions est appelée «analyse du flux de puissances incertaines». La détermination de bornes sur les modules des différentes tensions est formulée comme un problème d'optimisation convexe sous contraintes LMI. / This PhD thesis concerns robustness analysis (stability and performance) of uncertain large scale systems with hierarchical structure. These systems are obtained by interconnecting several uncertain sub-systems through a hierarchical topology. Robustness analysis of these systems is a two aspect problem: robustness and large scale. The efficient resolution of this problem using usual approaches is difficult, even impossible, due to the high complexity and the large size of the associated optimization problem. The consequence of this complexity is an important increase of the computation time required to solve this optimization problem. In order to reduce this computation time, the existing results in the literature focus on particular classes of uncertain linear large scale systems. Furthermore, the hierarchical structure of the large scale system is not taken into account, which means, from our point of view, that these results have several limitations on different levels. Our objective is to exploit the hierarchical structure to obtain a set of small scale size optimization problems instead of one large scale optimization problem which will result in an important decrease in the computation time. Furthermore, another advantage of this approach is the possibility of solving these small scale optimization problems in the same time using parallel computing. In order to take into account the hierarchical structure, we model the uncertain large scale system as the interconnection of uncertain sub-systems which themselves are the interconnection of other uncertain sub-systems, etc.. This recursive modelling is performed at several hierarchical levels. In order to reduce the representation complexity of uncertain systems, we construct a basis of dissipativity properties for each uncertain sub-system at each hierarchical level. This basis contains several elements which characterize different useful information about uncertain system behaviour. Examples of such characterizations are: uncertain phase characterization, uncertain gain characterization, etc.. Obtaining each of these elements is relaxed as convex or quasi-convex optimization problem under LMI constraints. Robustness analysis of uncertain large scale systems is then performed in a hierarchical way by propagating these dissipativity property bases from one hierarchical level to another. We propose two hierarchical analysis algorithms which allow to reduce the computation time required to perform the robustness analysis of the large scale systems. Another key point of these algorithms is the possibility to be performed in parallel at each hierarchical level. The advantage of performing robustness analysis in parallel is an important decrease of the required computation time. Finally and within the same context of robustness analysis of uncertain large scale systems, we are interested in robustness analysis of power networks and more precisely in "the uncertain power flow analysis in distribution networks". The renewable energy resources such as solar panels and wind turbines are influenced by many factors: wind, solar irradiance, etc.. Therefore, the power generated by these resources is intermittent, variable and difficult to predict. The integration of such resources in power networks will influence the network performances by introducing uncertainties on the different network voltages. The analysis of the impact of power uncertainties on the voltages is called "uncertain power flow analysis". Obtaining the boundaries for the different modulus of these voltages is formulated as a convex optimization problem under LMI constraints

Text in English / The study focused on the characterisation and management of non-formal solid waste disposal sites in Harare, the capital city of the Republic of Zimbabwe. In many developing countries, increasing urbanisation surpasses the development of urban infrastructure and this has led to the proliferation of informal settlements, illegal dumping sites and uncontrolled vending in cities like Harare. The researcher investigated the prevalence of non-formal dumping sites in Harare, including the composition, locational attributes and internal linkages of solid waste. Practices regarding the management of non-formal solid waste disposal sites were examined and areas of good practice and conformity to international standards were complemented while recommendations and suggestions were made on areas that were found wanting. An integrated management system was recommended for the sustainable management of solid waste. To support this recommendation, management window of responsibilities (EMWR) model was created so that the Harare City Council can enhance stakeholder participation. The research results show that most residents used non-conventional ways to store waste, like mealie-meal bags and sacks, and this posed a danger to human health. It also emerged that the city of Harare has not updated some of its by-laws, some of which were enacted about 33 years ago while others remained drafts for decades. This made it difficult for the city to effectively implement them. / Environmental Sciences / M.Sc. (Environmental Management)