Un code de simulation de plasma à deux dimensions électrostatique à coordonnées cartésiennes Particle-in-cell/ Monte Carlo Collision (PIC/MCC) est présenté, incluant un nouveau traitement de l'équilibre des charges aux limites diélectriques. Il est utilisé pour simuler un plasma dans le gaz Ar dans un réacteur à plaques parallèles à couplage capacitif à radiofréquence a géométrie symétrique avec une paroi latérale diélectrique épaisse. La paroi latérale diélectrique protège efficacement le plasma du champ électrique augmenté au niveau de la jonction entre l'électrode alimentée et l'électrode à la masse, dont on a montré précédemment qu'elle produisait une augmentation localise de la densité de plasma. Néanmoins, un réchauffement accru des électrons est observé dans une région adjacente à la limite diélectrique, conduisant à des maxima de le taux d'ionisation, de la densité du plasma et du flux ionique vers les électrodes dans cette région. Les différents composants du chauffage électronique sont dérivés des simulations PIC/MCC et montrent que cette augmentation du chauffage électronique provient d'un chauffage ohmique accru dans la direction axiale lorsque la densité électronique diminue vers la paroi latérale. Nous avons étudié la validité de différentes formules analytiques pour estimer le chauffage ohmique en les comparant aux résultats PIC. Le chauffage des électrons à composantes x a proximité des coins a été observé aux fréquences d'excitation plus élevées, provenant d'un champ RF oscillant important dans la direction x. / A Cartesian-coordinate two-dimensional electrostatic Particle-in-cell/Monte-Carlo Collision (PIC/MCC) plasma simulation code is presented, including a new treatment of charge balance at dielectric boundaries. It is used to simulate an Ar plasma in a symmetric radiofrequency capacitively-coupled parallel-plate reactor with a thick dielectric side-wall. The dielectric side-wall effectively shields the plasma from the enhanced electric field at the powered-grounded electrode junction, which has previously been shown to produce locally enhanced plasma density. Nevertheless, enhanced electron heating is observed in a region adjacent to the dielectric boundary, leading to maxima in ionization rate, plasma density and ion flux to the electrodes in this region. The electron heating components are derived from the PIC/MCC simulations and show that this enhanced electron heating results from increased Ohmic heating in the axial direction as the electron density decreases towards the side-wall. We investigated the validity of different analytical formulas to estimate the Ohmic heating by comparing them to the PIC results. The x component electron heating near the corners was observed at higher driving frequency, which is caused by a significant RF oscillating field in the x direction.

L’objectif de cette thèse consiste à mettre en place un système d’émulsion catalysé par des nanoparticules de Pickering afin de synthétiser des tensioactifs bio sourcés. Pour cela nous nous sommes intéressés à des matériaux mésoporeux fonctionnalisés (de type MCM-41). Ces matériaux favorisent la formation des émulsions tout en catalysant la réaction.Après une étude bibliographique sur le glycérol, les tensioactifs, les émulsions de Pickering et les matériaux mésoporeux, nous nous sommes intéressés à la synthèse et à la fonctionnalisation de ces matériaux. Puis après les avoir caractérisés, nous les avons testés dans des réactions modèles biphasiques (acétalysation et hydrolyse d’ester). Enfin, nous avons terminé cette étude en testant ces catalyseurs dans notre réaction cible (éthérification du glycérol par des alcools gras). La MCM-41 a été synthétisée en utilisant un chauffage micro-onde.Les fonctions greffées sur nos matériaux ont permis de faire varier la balance hydrophile hydrophobe de nos matériaux tout en leur fournissant une fonction catalytique. Les nanoparticules ont été caractérisées par leur ATG, BET, DRX, analyse élémentaire, acidité et tailles des particules.Des catalyseurs à base d’Aerosil® 200 et de Nanoparticules de carbone ont également été testés.Une longue chaine alkyke (C18) et des nanoparticules de petites tailles (Aerosil® 200 et nanoparticules de carbone) favorisent la stabilité des émulsions. Cependant la présence de pores dans nos matériaux n’apporte pas d’avantage catalytique déterminant. / The objective of this work is the conception of emulsion catalysed by Pickering nanoparticles inorder to synthetize biosurfactant. Our strategy was based on functionalised mesoporous materials(MCM-41). These materials combine both emulsion stabilisation and reaction catalysis.After a bibliographic study on glycerol, surfactants, Pickering emulsions and mesoporousmaterials; our strategy was to functionalise these materials. After charaterisation, these materialswere tested in bipohasic model reactions (acetalysation and ester hydrolysis). We come to the end of this study by testing these catalysts in our target reaction (glycerol etherifaction from fattyalcohol).The MCM-41 was synthetized by using a microwave heating. The grafted functions on our materials can both make several hydrophilic-hydrophobic materialsas possible and provided them some catalytic functions. The nanoparticles were characterized byTGA, BET, XRD, elemental analysis, acidity and particle size.Catalyst from Aerosil® 200 and carbon nanoparticles were also tested. A long alkyl chain (C18) and small nanoparticles (Aerosil® 200 and carbon nanoparticles) supportthe emulsion’s stability. Nevertheless, the porous inside our materials is not interesting on acatalytic point of view.

Este trabalho foi concebido inicialmente através de projeto, montagem e ensaios preliminares de uma unidade analógica, para propósito didático, composta de um servomecanismo controlado pelas clássicas estratégias Proporcional, Integral e Derivativa (PID). Com este equipamento foi demonstrado os conceitos fundamentais da engenharia de controle com seus ensaios e medidas que permitem exemplificar, de forma simples e bastante pedagógica, o funcionamento e os limites operacionais de um controlador prático. Os valores medidos em experimento foram comparados com valores obtidos pela simulação numérica de um modelo equivalente implementado no software MatLab. Utilizando-se da tecnologia PIC (Controlador de Interface Programável), o hardware analógico foi substituído, com a intenção de comparar os resultados para melhor ilustrar os abstratos conceitos da ação PID sobre um dispositivo eletromecânico razoavelmente linear. A unidade desenvolvida permite estabelecer um elo valioso à aprendizagem, buscando unir a teoria clássica, a simulação numérica, a aplicação digital e o comportamento real em uma situação física. Tivemos êxito nos resultados, conseguindo comprovar as modelagens matemáticas em aplicações práticas, além de poder comparar os desempenhos dos resultados analógicos com os resultados digitais. / This work was initially conceived by design, assembly and preliminary tests of an analogic unit, for didactic purpose, composed of a servomechanism controlled by the classic strategies Proportional, Integral and Derivative (PID). With this device was demonstrated the fundamental concepts of control engineering and its trials and measures allow exemplify, in a simple and very interactive way, the functioning and the operational limits of a practical controller. The values measured in assay were compared with values obtained by numerical simulation of an equivalent model implemented in MatLab. By using the technology PIC (Programmable Interface Controller), the analogical hardware will be substituted, in order to compare the results to better explain the abstract concepts of the PID action over a sufficiently linear electromechanical device. The developed unit enables a valuable link to the learning, seeking to unite the classical theory, numerical simulation, digital application and real performance in a physical case. We were successful in results, obtaining proof of the mathematical models in practical applications, besides being able to compare the performances of analogic results with digital ones.

Le domaine de la physique des plasmas froids a émergé avec les premières découvertes fondamentales en physique atomique et en physique des plasmas il y a plus d’un siècle. Toutefois, ce domaine a été rapidement orienté vers les applications. L’une des plus importantes dans la première moitié du XXème est le "Calutron" (California University Cyclotron), inventé par E. Lawrence à Berkeley, qui faisait partie du projet Manhattan, et utilisé comme un spectromètre de masse pour séparer les isotopes de l’uranium. Dans un rapport du projet Manhattan daté de 1949, D. Bohm fait deux observations qui sont fondamentales pour la physique des plasmas froids :(i) Les ions doivent avoir une énergie cinétique minimales lorsqu’ils entrent dans la gaine du plasma, estimée à Te/2, Te étant la température électronique.(ii) Le transport du plasma à travers un champ magnétique est augmenté par des instabilités.La propulsion électrique par plasma est utilisée pour des satellites militaires et des sondes spatiales depuis les années 1960 et a suscité un intérêt grandissant ces vingt dernières années avec le développement des applications commerciales des technologies spatiales. Néanmoins, les mêmes questions que celles auxquelles D. Bohm était confronté, c’est-à-dire le transport multidimensionnel, l’interaction plasma-gaine, et les instabilités, se posent toujours. La théorie et les simulations sont d’autant plus importantes pour la conception des systèmes de propulsion électrique que les tests en conditions réelles nécessitent le lancement d’un satellite dans l’espace.Dans ce travail, nous établissons les équations du transport multidimensionnel dans un plasma isotherme, nous proposons un critère de gaine qui permet de rendre compte de la saturation du champ magnétique dans un plasma froid et faiblement ionisé, et nous modélisons le refroidissement des électrons à travers le filtre magnétique du propulseur PEGASES (Plasma Propulsion with Electronegative Gases). Toutes les théories sont motivées et validées par un grand nombre de simulations particulaires PIC bi-dimensionnelles, en utilisant le code LPPic qui a été partiellement développé dans le cadre du projet. Enfin, les cas de simulation sont étendus à une décharge inductive à plasma dans l’iode, avec un nouvel ensemble de section efficaces de réaction. / The field of low temperature plasma physics has emerged from the first fundamental discoveries in atom and plasma physics more than a century ago. However, it has soon become very much driven by applications. One of the most important of them in the first half of the XXth century is the "Calutron" (California University Cyclotron) invented by E.~Lawrence in Berkeley, that was part of the Manhattan project, and operated as a mass spectrometer to separate uranium isotopes. In a 1949 report of the Manhattan project, D.~Bohm makes two observations that are fundamental for low-temperature plasma physics.(i) The ions must have minimum kinetic energy when they enter the plasma sheath estimated to T_e/2 , Te being the electron temperature in eV ;(ii) Plasma transport across a magnetic field is enhanced by instabilities.Plasma electric propulsion is used on military satellites and space probes since the 1960s and has gained more and more interest for the last twenty years as space commercial applications were developing. However, the same questions as the ones D.~Bohm was faced with, namely multi-dimensional transport, plasma sheath interaction, and instabilities, arise. Theory and simulation are even more important for electric space propulsion systems design since testing in real conditions involves to launch a satellite into space.In this work, we derive the equations of the multi-dimensional isothermal plasma transport, we establish a sheath criterion that causes the magnetic confinement to saturate in low-temperature, weakly ionized plasmas, and we model the electron cooling through the magnetic filter of the PEGASES (Plasma Propulsion with Electronegative Gases) thruster. All the theories are driven and validated with extensive two-dimensional particle-in-cell (PIC) simulations, using the LPPic code that was partially developed in the frame of this project. Finally, the simulation cases are extended to an iodine inductively coupled plasma (ICP) discharge with a new set of reaction cross sections.

There are various digital teaching materials as expected due to the always increasing and changing digitization. Digitization is widespread in our everyday lives and our school system. Teaching mathematics is no exception. The national agency for education in Sweden describes digitization as closely connected to teaching mathematics which can be read in the national curriculum.   The purpose of the survey was to see to what extent teachers use digital teaching materials and how they use it in their mathematics teaching. There were 87 mathematics teachers who participated and answered the questions, to what extent teachers use digital teaching materials and how they use it in their mathematics teaching.    With support of PIC-RAT, MDTDK and Choppin- framework, the answers were analyzed and the results indicate that most teachers use digital teaching materials in mathematics teaching, at least once a week. Many teachers use digital teaching materials several times a week and as a variation and extending the context, by choosing exercises and making adjustments for the students needs and levels. / Det finns mycket olika digitala läromedel vilket kan ses som en effekt då digitaliseringen är en ständigt växande och föränderlig faktor som påverkar både i vardagen såsom i skolverksamheten. Matematikundervisningen är inte ett undantag. Skolverket beskriver digitaliseringen som nära kopplad till just matematikundervisningen vilket kan ses i läroplanen. Syftet med studien var att undersöka i vilken utsträckning som lärare använder digitala läromedel samt hur dem används i matematikundervisningen. I studien svarade 87 lärare som undervisar i matematik på en enkät om hur digitala läromedel används i matematikundervisningen och i vilken utsträckning det görs. Med hjälp av valda ramverken PIC-RAT, MDTDK samt Choppin analyserades svaren från respondenterna. Resultaten visar att en stor andel lärare använder digitala läromedel i matematikundervisningen vid minst ett tillfälle i veckan. Många lärare använder digitala läromedel flera gånger i veckan och för att skapa en variation i undervisningen men även för att bredda matematikundervisningens innehåll. Lärarna gör det genom att välja uppgifter och göra anpassningar i det digitala läromedlet utifrån elevernas behov och nivå.

There is suggestion of obtaining exact position in this work, based on GPS and GSM modules controlled by PIC microcontroller. Layout of this work is electronic schematic, PCB footprint and theoretical analysis of used modules. The practical part of work is also dealing with software for both microprocessor and web interface. The function prototype will be created and tested in next phases of this project.

This report summarizes the work conducted during a six-month internship at Lawrence Berkeley National Laboratory. The main objective was to implement the interactions between particles and surfaces in the particle-in-cell code WarpX. This work specifically addressed the scenario where particles collide with embedded surfaces, which can potentially result in the emission of secondary particles. The implementation represents a significant advancement in the development of WarpX, enabling users to include interactions such as secondary particle emission and reflection in their simulations. Furthermore, this work also offered initial insights into the spacecraft charging problem and other scenarios involving particle-surface interactions. / Denna rapport sammanfattar det arbete som utförts under en sex månader lång praktikperiod vid Lawrence Berkeley National Laboratory. Huvudsyftet var att implementera interaktionen mellan partiklar och ytor i partikel-i-cell-koden WarpX. Detta arbete behandlade specifikt scenariot där partiklar kolliderar med inbäddade ytor, vilket potentiellt kan leda till utsläpp av sekundära partiklar. Implementeringen utgör ett betydande framsteg i utvecklingen av WarpX, vilket gör det möjligt för användare att inkludera interaktioner som emission och reflektion av sekundära partiklar i sina simuleringar. Dessutom gav detta arbete också inledande insikter i rymdfarkostens laddningsproblem och andra scenarier som involverar interaktioner mellan partiklar och ytor.

The design and analysis of various distributed space time block coding schemes for cooperative relay networks is considered in this thesis. Rayleigh frequency flat and selective fading channels are assumed to model the links in the networks, and interference suppression techniques together with an orthogonal frequency division multiplexing (OFDM) type transmission approach are employed to mitigate synchronization errors at the destination node induced by the different delays through the relay nodes. Closed-loop space time block coding is first considered in the context of decode-and-forward (regenerative) networks. In particular, quasi orthogonal and extended orthogonal coding techniques are employed for transmission from four relay nodes and parallel interference cancellation detection is exploited to mitigate synchronization errors. Availability of a direct link between the source and destination nodes is studied. Outer coding is then added to gain further improvement in end-to-end performance and amplify-and-forward (non regenerative) type networks together with distributed space time coding are considered to reduce relay node complexity. A novel detection scheme is then proposed for decode-and-forward and amplify-and-forward networks with closed-loop extended orthogonal coding and closed-loop quasi-orthogonal coding which reduce the computational complexity of the parallel interference cancellation. The near-optimum detector is presented for relay nodes with single or dual antennas. End-to-end bit error rate simulations confirm the potential of the approach and its ability to mitigate synchronization errors.

The most common type of electric propulsion in space exploration is the Hall Effect Thruster (HET), mainly due to its high specific impulse and high thrust to power ratio. However, uncertainties about the thruster's lifetime prediction have prevented widespread integration of HETs. Among these limitations, wall erosion of acceleration channel is of greatest concern. The experimental methods of erosion are time consuming and costly, and they are often limited to one single configuration. Hence, developing a computational model not only decreases the costs but also shortens the design time of a HET. This thesis investigates the feasibility of a uid erosion modelling with a multi-physics software (COMSOL) to further decrease the time and the development cost. First of all, this thesis provides an overview of available plasma modelling techniques and the physics behind the erosion phenomenon. Moreover, the effective parameters and available modules in the multiphysics software as well as their theoretical background were studied and discussed in detail. The Electron Anomalous phenomenon and pressure instability are determined as the main limiting factors for such a model. A non-magnetized model is included to find an optimal value for pressure and to reduce the probability of pressure instability occurrence in magnetized model. To fulfill this task, several simulations for various pressure values (0.005 Torr, 0.05 Torr, and 0.5 Torr) were conducted. Next, the simulation of magnetized/full model has been carried out with addition of magnetic coils in non-magnetized model. To avoid the Electron Anomalous phenomenon, the Bohm diffusion approach was implemented. In addition, a full Particle-In-Cell (PIC) simulation of a typical HET (SPT-100) with the similar input parameters as in fluid model was conducted, and the results were compared and validated using experimental data. The PIC model was intended to be utilized to investigate the accuracy of erosion model in multiphysics software. The results of this thesis indicate that current application of erosion model in COMSOL is not possible whilst high accuracy of the erosion model based on PIC approach can be achieved. Finally, the application of semi-empirical method through direct input of magnetic field data can allow short time simulation of a HET in COMSOL to gain insight about the preliminary behaviour of plasma, however, the simulation of an erosion model requires either a built-in PIC algorithm in COMSOL or a PIC based code.

Les buts de cette thèse étaient d’évaluer les taux de 25(OH)D chez des jeunes adultes Libanais et d’explorer les relations entre la 25(OH)D, la vitamine D libre et plusieurs paramètres osseux dans la même population. Dans un premier temps, nous avons démontré que l’insuffisance en 25(OH)D est très fréquente chez les jeunes adultes libanais (66 % des femmes vs. 50,7 des hommes) et que les taux de 25(OH)D ne sont pas des déterminants positifs de la DMO. Dans un deuxième temps, nous avons démontré que la 25(OH)D était positivement corrélée au BSI et au CSI dans les deux sexes et que certaines de ces corrélations ont persisté même après ajustement pour l’IMC. Dans un troisième temps, nous avons démontré que les taux de 25(OH)D sont positivement corrélés au TBS dans les deux sexes et que les valeurs de TBS sont supérieures chez les sujets ayant des taux suffisants (> 30 ng/ml) en 25(OH)D par rapport aux sujets ayant des taux insuffisants (< 30 ng/ml) en 25(OH)D. Dans un dernier temps, la vitamine D libre était positivement corrélée à plusieurs paramètres osseux dans les deux sexes ; certaines corrélations ont persisté même après ajustement pour le poids corporel. En conclusion, la 25(OH)D est un déterminant positif de plusieurs paramètres osseux chez les jeunes adultes Libanais. De plus, la vitamine D libre semble être un déterminant positif de plusieurs paramètres osseux dans cette population. La mesure des deux formes de vitamine D (25(OH)D et vitamine D libre) est intéressante pour l’évaluation et la prévention de l’ostéoporose. / The aims of this study were to evaluate the levels of 25(OH)D in a group of young Lebanese adults and to explore the relations between 25(OH)D, free vitamin D and many bone parameters in the same population. First, we have demonstrated that vitamin D insufficiency is very frequent in young Lebanese adults (66% in women vs. 50.7 % in men) and that levels of 25(OH)D are not positive determinants of BMD. Second, we have shown that 25(OH)D was positively correlated to BSI and CSI in both sexes, and some of these correlations remained significant after adjustment for BMI. Third, we have demonstrated that 25(OH)D levels were positively correlated to TBS in both sexes and that TBS values were higher in vitamin D sufficient (> 30 ng/ml) subjects compared to vitamin D insufficient subjects (< 30 ng/ml). Finally, free vitamin D was positively correlated to many bone parameters in both sexes; some of these correlations remained significant after adjustment for body weight. In conclusion, 25(OH)D is a positive determinant of many bone parameters in young Lebanese adults. Moreover, free vitamin D seems to be a positive determinant of many bone parameters in this population. The measurement of both forms of vitamin D (25(OH)D and total vitamin D) is interesting for the evaluation and the prevention of osteoporosis.