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Ammonia has shown great potential as a carbon-free fuel, in particular for marine transportation and energy production. Its low laminar flame speed, and the tradeoff between ammonia slip and NOx emission, pose challenges for industrial applications, and a more in-depth understanding of the combustion of ammonia is therefore needed. Raman spectroscopy is a powerful diagnostic often employed to investigate turbulence chemistry interactions and resolve the thermo-chemical structure of hydrogen and hydrocarbon-air flames. However, this technique has been used extensively in hydrocarbons (HCs) and hydrogen flames, but no quantitative Raman spectroscopy is available for ammonia flames, despite the current interest in ammonia combustion. First, this work extends Raman spectroscopy to the instantaneous and spatially resolved measurement of major species concentrations and temperatures in ammonia flames. The lack of detailed ammonia spectra at high temperatures, the strong flame luminosity, and fluorescence interference are the major obstacles to the implementation of Raman spectroscopy to ammonia flames. This thesis introduces a novel approach to estimating the temperature dependence of the Raman signal and fluorescence interference contributions from a series of counterflow diffusion flames. Species concentrations and temperature profiles from measurements are shown, and their accuracy and precision are discussed. Next, this work obtains the first quantitative Raman measurements of temperature, mass fractions, and mixture fractions in two turbulent ammonia/hydrogen/nitrogen diffusion jet flames simulating 14% (CAJF14) and 28% (CAJF28) partial ammonia cracking ratio with Reynolds numbers of 11,200. The scalar structure in turbulent flames is examined using conditional mean and RMS radial profiles, scatterplots in mixture fraction space, as well as statistics conditioned on mixture fraction and physical spaces. Finally, the probability of localized extinction and the differential diffusion (diff-diff) effects are analyzed in two turbulent flames. Lastly, an improved Raman/Rayleigh system is introduced for ammonia combustion at atmospheric pressure, which enables the 1D simultaneous laser-induced fluorescence (LIF) measurements of the amidogen (NH2) radical and interference-free Raman/Rayleigh measurements of major species and temperature in non-premixed and premixed NH3/H2-air flames.

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The Rayleigh-Ritz method is a convenient tool for the analysis of deflections in structures subjected to external forces. Bending moment relations can be developed and reliable values obtained for bending moments. In this thesis the Rayleigh-Ritz method is used for the analysis of a single-span, pin-connected circular arch subjected to uniform load along the arch. The method is explained, equations for deflections and moments are developed and the results of an illustrated problem are tabulated. The illustrated problem is also solved by a conventional method using the dummy load and virtual work techniques. Results are compared and found to be good. In both methods, account is taken of bending and axial forces; shear distortion is neglected. For the Rayleigh-Ritz method where undetermined coefficients are evaluated, a tabulation of the rate of convergence is presented. Computer programs for both methods are included. / Master of Science

The transport of a species in complex flow fields is an important phenomenon related to many areas in science and engineering. There has been significant progress theoretically and experimentally in understanding active transport in steady, periodic flows such as a chain of vortices but many open questions remain for transport in complex and chaotic flows. This thesis investigates the active transport in a three-dimensional, time-dependent flow field characterized by a spatiotemporally chaotic state of Rayleigh-Be?nard convection. A nonlinear Fischer-Kolmogorov-Petrovskii-Piskunov reaction is selected to study the transport within these flows. A highly efficient, parallel spectral element approach is employed to solve the Boussinesq and the reaction-advection-diffusion equations in a spatially-extended cylindrical domain with experimentally relevant boundary conditions. The transport is quantified using statistics of spreading and in terms of active transport characteristics like front speed and geometry and are compared with those results for transport in steady flows found in the literature. The results of the simulations indicate an anomalous diffusion process with a power law 2 < ? < 5/2 a result that deviates from other superdiffusive processes in simpler flows, and reveals that the presence of spiral defect chaos induces strongly anomalous transport. Additionally, transport was found to most likely occur in a direction perpendicular to a convection roll in the flow field. The presence of the spiral defect chaos state of the fluid convection is found to enhance the front perimeter by t^3/2 and by a perimeter enhancement ratio r(p) = 2.3. / Master of Science

A geotechnical composite foundation system that has become increasingly popular over the years is a column-supported, geosynthetic-reinforced embankment. This system consists of strong columns or piles placed in soft clay, a bridging layer of sand or sand and gravel, and one or more layers of geosynthetic reinforcement. It is often used in soft ground situations where there is a need for faster construction and/or where there are adjacent structures that would be affected by settlement caused by the new embankment. The geosynthetic reinforcement is placed in the bridging layer to help transfer the load to the columns and decrease the total and differential settlements. Current methods of analysis for this material are extremely simplified, and do not thoroughly model the behavior of the system. Therefore, a more comprehensive analysis needs to be conducted that will better predict the true effect of the geosynthetic layer or layers. In this thesis, one geosynthetic layer was considered. Models were developed using two different computer programs: Mathematica and ABAQUS. In Mathematica, the Rayleigh-Ritz method was used to approximate the deflections and tensile forces in the membrane. This method considered the geosynthetic reinforcement as a plate and minimized the total energy of the system. In ABAQUS, a finite element modeling program, the membrane was analyzed as a shell, and results were compared with some results from Mathematica. A parametric study was completed in Mathematica to determine the effects of different parameters. The parameters varied involved the geogrid properties (Poisson's ratio, modulus of elasticity, and thickness), the vertical load, the soil stiffness above the piles, the soil stiffness between the piles, the size of the piles, and the distance between the piles. / Master of Science

Le travail de recherche mené au cours de cette thèse a été effectué dans le cadre d’une collaboration industrielle et a porté sur la technologie de prilling et le développement de microparticules lipidiques par cette technique originale. La première partie de ce travail a consisté à sélectionner des excipients lipidiques puis à étudier leurs comportements lors des deux grandes étapes du procédé : la formation de la goutte par rupture vibrante et la cristallisation par refroidissement brutal dans la tour de prilling. Ces études ont permis de mettre en évidence des paramètres clés pour la réussite du procédé et donc pour la qualité du produit fini : la viscosité et les propriétés thermiques et structurales des lipides. Ces paramètres devront donc faire l’objet d’une étude systématique avant d’envisager leur application à la technologie de prilling. La seconde partie de ce travail concerne la formulation de trois molécules actives par prilling : le Kétoprofène, la Dronédarone et la Fexofénadine. Ces trois exemples ont permis d’illustrer différents modes d’incorporation du principe actif dans le procédé et leurs problématiques associées : la fusion, la solubilisation ou la mise en suspension d’un principe actif dans les excipients fondus. / This work was conducted within the framework of an industrial collaboration and focused on the prilling technology and the development of lipid microparticles by this original technique.The first part of this work was to select lipid excipients and to study their behavior in the two main steps of the process: the droplet’s formation by vibrating nozzle and the droplet’s crystallization by quenching in the prilling tower. These studies highlight the critical key parameters involves in the success of the process and therefore the quality of the final product: viscosity and thermal and structural properties of lipids. These parameters should be therefore systematically studied before considering their application to technology prilling.The second part of this work concerns the formulation of three active molecules by prilling: Ketoprofen, Dronedarone and Fexofenadine. These three examples were used to illustrate different ways of incorporating the active ingredient in the process and their associated problems: the melting, the solubilisation and the suspension of active molecules in melted lipids.

Le développement des instabilités hydrodynamiques lors d'une expérience de fusion par confinement inertiel représente un sévère obstacle à l'obtention des conditions nécessaires à l'allumage et l'auto-entretien des réactions thermonucléaires. Il est ainsi crucial de comprendre, modéliser et éventuellement contrôler ces instabilités. L'instabilité se développant au front d'ablation est particulièrement étudiée dans le cadre du schéma d'attaque directe, à cause notamment du phénomène d'empreinte laser. Cependant le stade fortement non-linéaire de l'instabilité de Rayleigh-Taylor au front d'ablation reste peu explore. Cette étude vise donc à analyser ce régime.Dans un premier temps, une nouvelle plateforme expérimentale est développée sur le laser National Ignition Facility (NIF) permettant l'étude de phénomènes hydrodynamiques avec plusieurs dizaines de nanosecondes d'impulsion laser. Cette plateforme est ensuite calibrée avec l'étude de la croissance d'une perturbation 2D sous l'effet de l'instabilité de Rayleigh-Taylor. Une plateforme de simulations numériques 2D est également développée sur le code hydrodynamique CHIC capable de modéliser les expériences réalisées.L'étude du régime fortement non-linéaire de l'instabilité de Rayleigh-Taylor est réalisée a partir d'une perturbation multimode 3D imprimée par laser.L'impact de la condition initiale est étudiée en utilisant un faisceau d'empreinte lisse d'une part et non lisse d'autre part. L'analyse des données de radiographie dans l'espace de Fourier et dans l'espace réel permet d'évaluer tous les différents paramètres de l'instabilité (taux de croissance linéaire, vitesses de saturation, taux de coalescence de bulles et paramètre de croissance auto-semblable ) et de comparer les mesures aux modèles existants.L'importance de la condition initiale au stade fortement non-linéaire de la perturbation est ainsi démontrée dans les résultats obtenus. / Experimental and numerical study of the non-linear stage of the ablative Rayleigh-Taylor instability in direct drive