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This study investigates the complex flow structure generated by riparian emergent vegetation along the edge of floodplain. Detailed velocity and boundary shear stress measurements were carried out for various arrangements of emergent rigid cylindric rods of 3 mm, 6 mm and 9 mm diameters and for three different rod densities. In addition, the impact of foliage on the flow field was assessed during a series of experiments where brushes were used instead of smooth rods. The results of these new experiments are first presented. In addition to the laboratory data, field data was obtained through Acoustic Doppler Current Profiler measurements for two flood events in a stretch of the river Rhône that can be approximated to a straight compound channel with vegetated banks. The analysis of the flow structure highlights the presence of strong secondary circulation and increased vorticity on the river banks. The rods on the edge of the floodplain increase significantly flow resistance, reducing velocity and decreasing boundary shear stress. Flow rate was seen to decrease with increasing vegetative density for all cases except when foliage was added. This suggests that an optimum threshold density, for which a smaller density would lead to an increased flow rate might exist. Wakes trailing downstream of the vegetation stem, planform coherent structures advected between the main channel and the floodplain, and eddying motion in the flow due to enhanced turbulence anisotropy are among the defining patterns observed in the studied compound channel flows with one line of emergent vegetation along the edge of the floodplain. The Shiono and Knight Method (SKM) was modified in order to account for the increased turbulence activity due to the rods. The drag force term was introduced in the same way as in the work of Rameshwaran and Shiono (2007). However, a new term was added to the transverse shear stress term in the form of an Elder formulation, incorporating a friction drag coefficient which can be derived from the experimental data. In this proposed version, the advection term was set to zero. Another version of the SKM, similar to Rameshwaran and Shiono (2007), was also tested with the addition of a local drag friction only applied in the rod region. The proposed SKM version without the advection term was favored as it can be more closely related to the experimental data and to physical processes. Finally, the capabilities of Telemac-2D were tested against the experimental data for various turbulence models. The Large Eddy Simulation turbulence model highlighted some unsteady flow patterns that were observed during experiments, while satisfactorily predicting the lateral velocity and boundary shear stress distributions.

Nous étudions des classes d'automates à états finis calculant sur les arbres, étendus par des contraintes permettant de tester des égalités et diségalités entre sous-arbres. Nous nous concentrons sur des automates d'arbres à contraintes globales où les tests sont opérés en fonction des états que l'automate atteint lors de ses calculs. De tels automates ont été introduit dans le cadre de travaux sur les documents semi-structurés. Nous procédons ici à une comparaison détaillée en expressivité entre ces automates et d'autres modèles permettant de réaliser des tests similaires, comme les automates à contraintes entre frères ou les automates d'arbres avec une mémoire auxiliaire. Nous montrons comment de tels automates peuvent être utilisés pour vérifier des propriétés de sécurité sur les protocoles cryptographiques. Les automates d'arbres ont déjà été utilisés pour modéliser les messages échangés lors d'une session d'un protocole. En ajoutant des contraintes d'égalité, nous pouvons décrire précisement des sessions qui utilisent à plusieurs reprises un même message, évitant ainsi une approximation trop grande. Nous répondons ensuite positivement au problème de la décision du vide des langages reconnus par les automates à contraintes globales. En montrant que leur expressivité est très proche de celle des automates opérant sur des représentations de termes par des graphes orientés acycliques, nous en déduisons une procédure de décision du vide en temps non-déterministe doublement exponentiel. Finalement, nous étudions le problème de la décision du vide pour des automates à contraintes globales pour lesquels on autorise des contraintes dites de clé, exprimant intuitivement que tous les sous arbres d'un certain type dans un arbre en entrée sont distincts deux à deux. Le type des clés est classiquement utilisé pour représenter un identifiant unique, comme un numéro de sécurité sociale.Nous décrivons alors une procédure de décision du vide de complexité non-élementaire. Nous montrons que cette procédure est très robuste, et qu'il est possible d'étendre les automates avec des contraintes supplémentaires, comme des contraintes de comptage ou des tests locaux, tout en préservant la décidabilité du vide. / We study here several classes of finite state automata running on trees, extended with constraints that allow to test for equalities or disequalities between subterms. We focus on tree automata with global constraints where the tests are done depending on the states reached by the automaton on its runs. Such automata were introduced in studies on semi-structured documents. We do here a detailed comparison between those automata and other models that allow to operate similar tests, like tree automata with constraints between brothers, or tree automata with an auxiliary memory. We show how such automata may be used to verify security properties on cryptographic protocols. Tree automata have already been used to modelize the messages exchanged during a protocol session. By adding equality constraints, we can describe precisely protocol sessions that use a same message several times, hence avoiding an approximation. Then, we answer positively the decision problem of the emptiness of the languages recognized by tree automata with global constraints. By showing that their expressivity is very close from the one of the automata operating on directed acyclic graphs representations of terms, we infer an emptiness decision procedure in double exponential non-deterministic time. Finally, we study the emptiness decision problem for automata with global constraints where we authorize "key constraints", that intuitively allow that all subtrees of a given type in an input tree are distincts. We give an emptiness decision procedure of non-primitive recursive complexity. Key constraints are classicaly used to represent a unique identifier. We describe a non-primitive recusrive emptiness decision procedure. We show that this procedure is very robust and that it allows to extend the automata with additionnal constraints, like counting constraints or local tests, while preserving decidability.

This dissertation focuses on the significance of containment relations between the above mentioned classes of ideals. The main problem considered in Chapter II is determining conditions which lead a ring to be a P-ring, D-ring, or AM-ring when every regular ideal is a P-ideal, D-ideal, or AM-ideal, respectively. We also consider containment relations between classes of regular ideals which guarantee that the ring is a quasi-valuation ring. We continue this study into the third chapter; in particular, we look at the conditions in a quasi-valuation ring which lead to a = Jr, sr - f, and a = v. Furthermore we give necessary and sufficient conditions that a ring be a discrete rank one quasi-valuation ring. For example, if R is Noetherian, then ft = J if and only if R is a discrete rank one quasi-valuation ring.

Performance and reliability of solid state laser diodes in the IR region exceeds those in the visible and UV part of the light spectrum. Single frequency visible and UV laser diodes with higher than 500 mW power are not available commercially. However we successfully stabilized a multi-longitudinal mode IR laser to 860 mW single frequency. This means high efficiency harmonic generation using this laser can produce visible and UV laser light not available otherwise. In this study we examined three major leading nonlinear crystals: PPMgO:SLN, PPKTP and PPMgO:SLT to generate blue light by second harmonic generation. We achieved record high net conversion efficiencies 81.3% using PPMgO:SLT (~500 mW out), and 81.1% using PPKTP (~700 mW out). In both these cases an external resonance buildup cavity was used. We also studied a less complicated single pass waveguide configuration (guided waist size of ~ 5 um compared to ~60 um) to generate blue. With PPMgO:SLN we obtained net 40.4% and using PPKT net 6.8% (110mW and 10.1 mW respectively).

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

La recombinaison hétérogène de molécules diatomiques influence de manière déterminante la réactivité chimique de certains plasmas froids vis à vis des matériaux. Dans ce travail la dynamique de formation de molécules d'azote (N2) sur des surfaces modèles de tungstène (W) est théoriquement décrite. La méthode des trajectoires quasi-classiques est employée pour simuler l'abstraction directe d'atomes d'azote initailement pré-adsorbés sur la surface, par les atomes provenant de la phase gazeuse : la recombinaison Eley Rideal. L'utilisation d'un modèle d'interactions suffisamment précis, basé sur un fit multidimensionnel de calculs ab initio, révèle les mécanismes de recombinaisons à l'échelle moléculaire et en particulier le rôle prépondérant joué par la répulsion à moyenne lors de l'approche des deux atomes d'azote. La possible dissipation aux phonons du matériau ainsi que le rôle de la température de surface sont pris en compte par un modèle effectif d'oscillateur de Langevin généralisé. L'influence de la symétrie de surface est enfin abordée par la comparaison de la dynamique de recombinaison pour deux surfaces d'orientation cristallographique différente W (100) et W (110). / Abstract

The Madden-Julian oscillation (MJO), also known as the 30-60day oscillation, is the strongest of the intraseasonal climate oscillations in the tropics and has significant derivative effects on extratropical circulation and intraseasonal climate. It has recently been shown that the stratospheric quasi-biennial oscillation (QBO) modulates the amplitude of the boreal winter MJO such that MJO amplitudes are larger on average during the easterly phase (QBOE) than during the westerly phase (QBOW). A major possible mechanism is the decrease in static stability in the lowermost stratosphere under QBOE conditions resulting from relative upwelling associated with the QBO-induced meridional circulation. Here evidence is presented that tropical upwelling changes related to the 11year solar cycle also modulate the boreal winter MJO. Based on 37.3years of MJO amplitude data, the largest amplitudes and occurrence rates, and the weakest static stabilities in the tropical lower stratosphere, occur during the QBOE phase under solar minimum (SMIN) conditions while the smallest amplitudes and strongest static stabilities occur during the QBOW phase under solar maximum (SMAX) conditions. Conversely, when the QBO and solar forcings are opposed (QBOW/SMIN and QBOE/SMAX), the difference in occurrence rates becomes statistically insignificant. During the coming solar minimum, at least one additional winter in the QBOE/SMIN category should occur (possibly as early as 2017/2018) during which especially large MJO amplitudes are expected and an initial test of these results will be possible. Plain Language Summary An ongoing issue in climate science is the extent to which upper atmospheric processes, including solar forcing, can influence tropospheric climate. It has recently been shown that an internal oscillation of the stratosphere, the quasi-biennial oscillation, can modulate the amplitude and occurrence rate of intraseasonal climate oscillations in the tropical Pacific during northern winter. These intraseasonal oscillations, the most important of which is the 30-60day Madden-Julian oscillation, have significant derivative effects on climate outside of the tropics, including impacts on rainfall events over the continental United States. Here evidence is presented that the amplitude of the Madden-Julian oscillation during northern winter is also modulated by the 11year solar cycle. The modulation is such that amplitudes and occurrence rates are largest under solar minimum conditions when the quasi-biennial oscillation is in its easterly phase and smallest under solar maximum conditions when the quasi-biennial oscillation is in its westerly phase. However, the available time record (37.3years of satellite measurements) is limited. During the coming solar minimum, at least one additional winter in the solar minimum/easterly category should occur (possibly as early as 2017/2018) during which larger-than-average amplitudes are expected and an initial test of the proposed relationship will be possible.

Doctor of Philosophy / Department of Mathematics / Diego Maldonado / Originally introduced in 1961 by Carl Gustav Axel Harnack [36] in the context of harmonic functions in R[superscript]2, the so-called Harnack inequality has since been established for solutions to a wide variety of different partial differential equations (PDEs) by mathematicians at different times of its historical development. Among them, Moser's iterative scheme [47-49] and Krylov-Safonov's probabilistic method [43, 44] stand out as pioneering theories, both in terms of their originality and their impact on the study of regularity of solutions to PDEs. Caffarelli's work [12] in 1989 greatly simplified Krylov-Safonov's theory and established Harnack's inequality in the context of fully non-linear elliptic PDEs. In this scenario, Caffarelli and Gutierrez's study of the linearized Monge-Ampere equation [15, 16] in 2002-2003 served as a motivation for axiomatizations of Krylov-Safonov-Caffarelli theory [3, 25, 57]. The main work in this dissertation is a new axiomatization of Krylov-Safonov-Caffarelli theory. Our axiomatic approach to Harnack's inequality in spaces of homogeneous type has some distinctive features. It sheds more light onto the role of the so-called critical density property, a property which is at the heart of the techniques developed by Krylov and Safonov. Our structural assumptions become more natural, and thus, our theory better suited, in the context of variational PDEs. We base our method on the theory of Muckenhoupt's A[subscript]p weights. The dissertation also gives an application of our axiomatic approach to Harnack's inequality in the context of infinite graphs. We provide an alternate proof of Harnack's inequality for harmonic functions on graphs originally proved in [21].

Master of Science / Department of Statistics / Leigh Murray / This case study was motivated by the need for effective statistical analysis for a series of poultry feeding experiments conducted in 2006 by Kansas State University researchers in the department of Animal Science. Some of these experiments involved an automated auger feed line system commonly used in commercial broiler houses and continuous, proportion response data. Two of the feed line experiments are considered in this case study to determine if a statistical model using a non-normal response offers a better fit for this data than a model utilizing a normal approximation. The two experiments involve fixed as well as multiple random effects. In this case study, the data from these experiments is analyzed using a linear mixed model and Generalized Linear Mixed Models (GLMM’s) with the SAS Glimmix procedure. Comparisons are made between a linear mixed model and GLMM’s using the beta and binomial responses. Since the response data is not count data a quasi-binomial approximation to the binomial is used to convert continuous proportions to the ratio of successes over total number of trials, N, for a variety of possible N values. Results from these analyses are compared on the basis of point estimates, confidence intervals and confidence interval widths, as well as p-values for tests of fixed effects. The investigation concludes that a GLMM may offer a better fit than models using a normal approximation for this data when sample sizes are small or response values are close to zero. This investigation discovers that these same instances can cause GLMM’s utilizing the beta response to behave poorly in the Glimmix procedure because lack of convergence issues prevent the obtainment of valid results. In such a case, a GLMM using a quasi-binomial response distribution with a high value of N can offer a reasonable and well behaved alternative to the beta distribution.