Les modulateurs electro-optiques (EOM) sont des composants importants dans les systemes de telecommunication. Malheureusement, ils ne sont pas parfaitement stables dans Ie temps et leur fonction de transfert (TF) a tendance a se decaler durant Ie temps d'operation. La derive de la TF d'un EOM peut etre expliquee par des effets differents tels que les changements de la temperature ambiante, de la polarisation ou de l'efficacite de couplage optique. La these presente une methode de me sure de la derive de la TF de I'EOM (a grace d'estimation du comportement non-linearite du modulateur, NLl), et propose deux systemes instrumentaux pour ameliorer son fonctionnement: Ie premier pour contraler la temperature de l'EOM, il est possible de forcement reduire cette derive, Ie deuxieme pour compenser la derive (la stabilisation du point de fonctionnement autour du point quadrature est obtenue jusqu'au 0,22% ou la fluctuation de phase est de 0,44°). Ces techniques ont ete aussi appliquees pour ameliorer Ie comportement d'un oscillateur optoelectronique haute frequence. Nous avons realise les experiences par asservissement de temperature, par compensation de la derive. Pour une stabilite de I'OEO a court terme, la stabilisation de la frequence est amelioree jusqu'a 28% en utilisant un contrale de temperature seule etjusqu'a 71 % avec les deux processus. Pour une stabilite de l'OEO a long terme, en deux cas sans contra Ie, I'OEO fonctionne pendant 3 heures et pendant 1,6 heure (puis I'OEO ne marche plus). En utilisant une compensation de la derive de la TF de I'EOM, l'OEO fonctionne bien meme apres 7 heures et 8 heures. / Electro-optic modulators (EOM) are important components in telecommunication systems. Unfortunately, there are some physical effects like ambient temperature variations, polarization and inherent photorefractive coefficient which are due to the drift of EOM transfer function (TF). The thesis presents a method for measuring the drift of the TF of EOM (based on a nonlinearity behavior of modulator - NLl), and propose two instrumentation systems to improve their operations: one to control the temperature of EOM, it is possible to significantly reduce the drift, the second to compensate the drift (the bias point stabilization around the quadrature point is obtained up to 0.22% or the phase fluctuation is 0.44°). These techniques have been applied to improve the behavior of an optoelectronic oscillator high frequency. Four experiments are carried out by controlling the EOM temperature and by compensating the EOM drift. For a short-term stability of OEO, the stabilization of the frequency is obtained with 28% with using a temperature control, up to 71 % with the two techniques. For a long-term stability of OEO, in cases without any control, the OEO has worked for 3 hours and for 1.6 hours (then, the OEO does not work anymore). By using the drift compensation of the EOM FT, the OEO has correctly worked even more than 7 hours and 8 hours.

La escasez de registros sísmicos de gran magnitud en algunas regiones del mundo limita la determinación de la respuesta sísmica de una edificación. En este sentido, los acelerogramas artificiales representan una alternativa para definir el evento sísmico porque consideran las condiciones específicas del sitio en estudio. Esta investigación analiza la respuesta sísmica de las estructuras para diversos registros sísmicos artificiales generados de espectros de diseño para distintas condiciones geotécnicas. El procedimiento de análisis empleado será el dinámico tiempo historia no lineal para obtener una mayor precisión en la respuesta sísmica. Los resultados obtenidos muestran que las derivas de entrepiso de las señales artificiales creadas con la función de intensidad de Liu se ajustan mejor a las derivas obtenidas del sismo real escalado. / The lack of large seismic records in some world regions limits the determination of the seismic response of a building. For that reason, artificial accelerograms represent an alternative to define the seismic event because they consider specific conditions of study site. This research analyses the structures seismic response for various artificial seismic records generated from design spectra and different geotechnical conditions. Dynamic nonlinear time history analyzing was used to obtain greater precision in the seismic response. The results obtained show that the mezzanine drifts of the artificial signals created with the Liu intensity function better fit the drifts obtained from the scaled real earthquake. / Trabajo de investigación

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This thesis is a study into the response and seismic safety of three-dimensional multi-storey concrete structures under concurrent orthogonal seismic excitations. It employs the nonlinear time-history method as its analysis tools. Time-history analyses rely heavily on their utilised earthquake records. Accordingly, this study examines the different approaches of selecting earthquake suites and develops a methodology of selecting representative earthquake scenarios. This methodology is credibly implemented in selecting a far- and a near field suites representative of the New Zealand seismic hazard. The study investigates the response of 6-, 9- and 12-storey concrete structures of different n-X-bays × m-Y-bays. Bidirectional responses of these considered structures are examined and consequently the current combination rules are scrutinised. Consequently this study strongly recommends the use of the 40-percent combination rule in lieu of the widely used 30-percent rule; and the use of time-history analysis in lieu of quasi/equivalent static and response modal analysis methods to avoid their strong dependence on combination rules. An intensive study is conducted employing the incremental dynamic analysis (IDA) technique to investigate structural demands of interstorey drifts, lateral storey drifts and storey accelerations. The study utilises the developed far-field suite and identifies the 50th and 90th percentile demands. Hence it provides easy-to-use expressions to facilitate rapid calculation of the structural demands and the effects of biaxial interactions. An implementation into the Demand and Capacity Factor Design (DCFD) format is presented that infers confidence in the performance levels of the considered structures. The study also draws attention to the importance of considering storey accelerations as their storey values reach as high as 10 × PGA. A sensitivity study is conducted by repeating the IDA investigation while using the developed near-field suite. Subsequently a comparison between the near- and the far-field results is conducted. The results were markedly similar albeit of less magnitudes until the (seismic hazard) intensity measure IM = Sa(T₁) = 0.4g when the near-field results show sudden flat large increase in demands suggesting a brittle collapse. This is attributed to the higher content of the higher mode frequencies contained in near-field ground motions. Finally, the study examines the (vectorial) radial horizontal shear demands in columns and beam-column joints of the previous far- and near-field studies. The combined radial shear demands in corner, edge and internal columns and joints are evaluated that roughly show a square-root proportional relationship with IM that exhibit somewhat brittle failure at IM ≥ 0.35g. Shears demands in the (4-way) internal columns and the (2-way) corner joints show highest magnitude in their respective class. The results suggest transverse joint shear reinforcement of 1.5, 1.0 and 0.5 of the longitudinal reinforcement of the neighbouring beam respectively for corner, edge and internal joints. An implementation of a proposed practical (and simpler) DCFD format shows satisfactory confidence in columns performance in shear up to IM = 0.35g, conversely to joints unsatisfactory performance in shear at the onset of inelastic behaviour (IM > 0.05g).

L’objectif de ce mémoire de maîtrise est de développer des outils de diagnostics non-invasifs et de caractériser in-situ les dérives de procédé dans un réacteur industriel utilisé en production pour la gravure profonde du silicium par le procédé Bosch. Ce dernier repose sur l’alternance d’un plasma de SF6 pour la gravure isotrope du Si et d’un plasma de C4F8 pour la passivation des parois dans l’optique d’obtenir des tranchées profondes et étroites. Dans un premier temps, nous avons installé une sonde courant-tension sur la ligne de transmission du signal rf au porte-substrat pour l’étude de son impédance caractéristique et un spectromètre optique pour l’étude de l’émission optique du plasma. Nos travaux ont montré que l’évolution temporelle de l’impédance constitue un excellent moyen pour identifier des changements dans la dynamique du procédé, notamment une gravure complète de la photorésine. De plus, à partir des spectres d’émission, nous avons pu montrer que des produits carbonés sont libérés du substrat et des parois lors de l’alternance passivation/gravure et que ceux-ci modifient considérablement la concentration de fluor atomique dans le plasma. Dans un second temps, nous avons développé un réacteur à « substrat-tournant » pour l’analyse in-situ des interactions plasma-parois dans le procédé Bosch. Nos travaux sur ce réacteur visaient à caractériser par spectrométrie de masse l’évolution temporelle des populations de neutres réactifs et d’ions positifs. Dans les conditions opératoires étudiées, le SF6 se dissocie à près de 45% alors que le degré de dissociation du C4F8 atteint 70%. Le SF6 est avant tout dissocié en F et SF3 et l’ion dominant est le SF3+ alors que le C4F8 est fragmenté en CF, CF3 et CF4 et nous mesurons plusieurs ions significatifs. Dans les deux cas, la chaîne de dissociation demeure loin d’être complète. Nous avons noté une désorption importante des parois de CF4 lors du passage du cycle de passivation au cycle de gravure. Un modèle d’interactions plasmas-parois est proposé pour expliquer cette observation. / The purpose of this master thesis is to develop non-invasive diagnostic tools for in-situ characterization of process drifts in an industrial reactor used in production for deep silicon etching by the Bosch process. This process alternates between a SF6 plasma for isotropic Si etching and a C4F8 plasma for sidewall passivation to achieve deep and narrow trenches. In this context, a current-voltage probe was installed on the rf transmission line to the substrate holder for impedance studies and an optical spectrometer for plasma optical emission spectroscopy. We have shown that the time evolution of the impedance represents an excellent tool for monitoring changes in the process dynamics, including the complete removal of the photoresist due to process drifts. In addition, based on emission spectroscopy, we have demonstrated that carbon products are released from the substrate and reactor walls during etching. A « spinning-wall » reactor was also developed for in-situ analysis of plasma-wall interactions. The main objective of our work on this reactor was to characterize the time evolution of the population of reactive neutrals and positive ions by plasma sampling mass spectrometry. Over the range of experimental conditions investigated, the percent dissociation of SF6 was 45%, while the one of C4F8 was 70%. SF6 was mostly dissociated in F and SF3, with SF3+ as the dominant ion. C4F8 is essentially fragmented in CF, CF3 and CF4 with many significant ions. In both cases, the dissociation chain remained incomplete. An important desorption of CF4 from the reactor walls was observed when going from passivation to etching cycles. A plasma-wall interaction model was proposed to explain such observation.

The transport of cosmic rays in the heliosphere is studied by making use of a newly developed modulation model. This model employes stochastic differential equations to numerically solve the relevant transport equation, making use of this approach’s numerical advantages as well as the opportunity to extract additional information regarding cosmic ray transport and the processes responsible for it. The propagation times and energy losses of galactic electrons and protons are calculated for different drift cycles. It is confirmed that protons and electrons lose the same amount of rigidity when they experience the same transport processes. These particles spend more time in the heliosphere, and also lose more energy, in the drift cycle where they drift towards Earth mainly along the heliospheric current sheet. The propagation times of galactic protons from the heliopause to Earth are calculated for increasing heliospheric tilt angles and it is found that current sheet drift becomes less effective with increasing solar activity. Comparing calculated propagation times of Jovian electrons with observations, the transport parameters are constrained to find that 50% of 6 MeV electrons measured at Earth are of Jovian origin. Charge-sign dependent modulation is modelled by simulating the proton to anti-proton ratio at Earth and comparing the results to recent PAMELA observations. A hybrid cosmic ray modulation model is constructed by coupling the numerical modulation model to the heliospheric environment as simulated by a magneto-hydrodynamic model. Using this model, it is shown that cosmic ray modulation persists beyond the heliopause. The level of modulation in this region is found to exhibit solar cycle related changes and, more importantly, is independent of the magnitude of the individual diffusion coefficients, but is rather determined by the ratio of parallel to perpendicular diffusion. / PhD (Space Physics), North-West University, Potchefstroom Campus, 2013

The transport of cosmic rays in the heliosphere is studied by making use of a newly developed modulation model. This model employes stochastic differential equations to numerically solve the relevant transport equation, making use of this approach’s numerical advantages as well as the opportunity to extract additional information regarding cosmic ray transport and the processes responsible for it. The propagation times and energy losses of galactic electrons and protons are calculated for different drift cycles. It is confirmed that protons and electrons lose the same amount of rigidity when they experience the same transport processes. These particles spend more time in the heliosphere, and also lose more energy, in the drift cycle where they drift towards Earth mainly along the heliospheric current sheet. The propagation times of galactic protons from the heliopause to Earth are calculated for increasing heliospheric tilt angles and it is found that current sheet drift becomes less effective with increasing solar activity. Comparing calculated propagation times of Jovian electrons with observations, the transport parameters are constrained to find that 50% of 6 MeV electrons measured at Earth are of Jovian origin. Charge-sign dependent modulation is modelled by simulating the proton to anti-proton ratio at Earth and comparing the results to recent PAMELA observations. A hybrid cosmic ray modulation model is constructed by coupling the numerical modulation model to the heliospheric environment as simulated by a magneto-hydrodynamic model. Using this model, it is shown that cosmic ray modulation persists beyond the heliopause. The level of modulation in this region is found to exhibit solar cycle related changes and, more importantly, is independent of the magnitude of the individual diffusion coefficients, but is rather determined by the ratio of parallel to perpendicular diffusion. / PhD (Space Physics), North-West University, Potchefstroom Campus, 2013

The work described in this thesis focuses on the effects that adsorption processes on catalytic surfaces pose in controlling key steps that can affect and control reaction pathways. To that, the development of Nuclear Magnetic Resonance (NMR) relaxometry methods and the comparison with traditional catalytic was performed with a series of C5 and C6 unsaturated hydrocarbons on two different alumina supports, γ- and θ-Al2O3. The developed techniques were applied in the study of liquid phase selective hydrogenation of citral on 5% Pt/SiO2. Infrared (IR) spectroscopy, volumetric adsorption isotherms, dynamic isotherms via a Tapered Element Oscillating Microbalance (TEOM), temperature programmed desorption (TPD) as well as 13C T1 NMR and 1H 2D T1-T2 relaxometry methods were employed. Energies of adsorption as a function of coverage were obtained via adsorption isotherms and the particular surface adsorbate interactions were described with IR spectroscopy. For example, 1-pentyne showed the strongest interaction with the alumina (94 kJ mol-1) while 1-pentene presented a weaker interaction (46 kJ mol-1) on θ-Al2O3. Desorption energies obtained from TPD ranged 85 – 130 kJ mol-1, irrespective of the adsorbate. Reactivity of the aluminas was captured with TPD, TEOM and NMR relaxometry. Interaction of adsorbates with hydrocarbon occurred predominantly on weak adsorption sites. 13C NMR T1 relaxometry provided in addition atom-specific adsorbate-adsorbent interaction strengths, showing the molecular geometry of adsorption, and applied in co adsorption measurements. The selective hydrogenation of citral as a model α,β-unsaturated aldehyde and the effect of different solvents on the activity and product distribution was studied at 298 and 373 K. A series of polar protic, polar aprotic and non polar solvents was investigated. Results showed higher initial reaction rates in non polar solvents but higher selectivities towards desired products on polar protic solvents. Solvent used also affected by product formation. The strong variations in reaction rates and selectivities reported were related with adsorbate catalyst interactions, as well as solvent reactant interactions. For example, adsorption isotherms showed that ethanol notably reduced the adsorption capacity of citral as compared with hexane, related with the rate differences observed. ATR-IR measurements indicated solvent citral interactions were solely present in polar protic solvents in line with higher yields of geraniol and nerol. Finally, 13C T1 NMR and 1H 2D T1-T2 correlation experiments determined that the geometry of adsorption of citral, influenced by solvent, affected product selectivity, and that product adsorption affected selectivity and deactivation.

La mondialisation économique et l'internationalisation des échanges ont engendré l'ouverture des frontières et la mobilité professionnelle. Par conséquent, de nouveaux besoins communicatifs émergent. En effet, les institutions, les organismes, les administrations et les entreprises recrutent, aujourd'hui, des professionnels capables de communiquer en plusieurs langues lors de leurs activités professionnelles. Pour répondre à cette demande, des établissements scolaires et universitaires ont mis en œuvre des dispositifs d'enseignement bi-plurilingue. La présente thèse s'intéresse aux Filières Universitaires Francophones (FUF) bi-plurilingues, et a pour objectif d'analyser le dispositif Discipline(s) Non Linguistique(s) (DNL)/cours de français, censé garantir la réussite universitaire et professionnelle des étudiants allophones. Ainsi, nous avons mené une enquête de terrain au sein d'une FUF d'économie en Egypte pour y étudier les pratiques linguistiques et didactiques. Notre recherche montre que l'intégration d'un cours de Français sur Objectif Universitaire (FOU) et de Français sur Objectif Spécifique (FOS) dans le programme de formation des FUF vise la réussite des étudiants. Par ailleurs, les résultats de notre investigation nous ont conduite à élaborer différents outils permettant aux enseignants de français d'élaborer plus facilement des cours de FOS/FOU. Il s'agit précisément de la conception d'un référentiel de compétences langagières, d'un programme de formation de FOS/FOU et d'activités pédagogiques. / The economic globalization and internationalization of exchanges led to the opening of borders and professional mobility. As a result, new communication needs are emerging. Indeed, institutions, organizations, administrations and enterprises are nowadays recruiting professionals who can communicate in different languages during their workplace activities. To meet this demand, schools and universities have implemented bi-multilingual teaching. This thesis focuses on bi-multilingual French-language University Courses (FUF) and aims to analyze the framework including non-linguistic subject(s) (DNL) in French and French courses, which is intended to ensure the academic and professional success of allophone students. Thus, we conducted a field survey within the Economics courses of a FUF in Egypt so as to study the linguistic and teaching practices. Our research shows that the integration of French for Specific Purposes (FSP) and French for Academic Purposes (FAP) courses in the FUF’s academic program aims at student achievement. Furthermore, the results of our investigation led us to develop different tools which will enable French teachers to create FSP/FAP courses more easily. More specifically, it is the construction of a competency framework, the design of a training program and educational activities.