For steady free-stream, zero and favorable pressure gradient turbulent boundary layers, the unsteadiness in the form of turbulent fluctuations was investigated. Phase ensemble-averaged flow characteristics of a large amplitude periodic unsteady turbulent boundary layer was also investigated at a reduced frequency k = 0.61 based on the length of the converging and diverging test section with amplitude to mean velocity ratio of 0.8. In steady flow cases, both zero and favorable pressure gradient flows show good two-dimensional flow characteristics and mean flow characteristics are compared with other researchers’ data. Measured power spectral data show good agreement with those of Klebanoff, Ueda and Hinze, Perry, Lim and Henbest for the zero pressure gradient flows and Jones and Launder for the favorable pressure gradient flow. The power spectral data measured in the turbulent wall region of the zero pressure gradient flow closely follow the model equation proposed by Perry, Lim and Henbest. Convective wave speed also show good agreement with those of Favre, Gaviglio and Dumas and Sternberg within the experimental uncertainties. In the inner region of the boundary layer where y+ < 40, convective wave speed is higher than local mean velocity at all eddy scales as observed by Kline, Reynolds, Schraub and Runstadler. In the unsteady flow case, in the absence of flow reversal, the flow behaves in a quasi-steady manner and can be described by the steady flow structure as in the case of moderate amplitude flows. The Ludwieg·Tillmann skin friction equation and the Perry-Schofield universal velocity defect law hold at these phases. Except the laminariscent velocity profile observed during the acceleration phases, the large amplitude unsteady flow shows basically the same flow characteristics as the moderate amplitude flows. / Master of Science

<p> The role of plastic deformation in the initiation and propagation of cracks in Cu-17Al alloy embrittled by liquid mercury has been studied. It is proposed that extensive plastic deformation and work hardening must occur at the crack-tip during propagation in order to raise the local flow stress to a critical level at which the maximum normal stress is equal to the cohesive strength. A crack initiation mechanism is proposed involving grain boundary diffusion enhanced by the stress concentration at the head of dislocation pile-ups at the grain boundary. Micro-cracks are formed at the weakened grain boundary and a period of stable crack growth made over a period of increasing applied stress may be necessary before the crack is long enough to become unstable.</p> / Thesis / Master of Science (MSc)

<p> A quasi-steady state optimization of an adiabatic, fixed bed tubular reactor, with catalyst decay, is considered.</p> <p> The optimal inlet temperature (distribution) To(t), is sought, so as to maximize the total amount of reaction in a fixed given period of time. Upper and lower bounds are placed on the inlet temperature.</p> <p> A single irreversible reaction is considered with a reaction rate expressible as separable functions of inlet temperature, conversion and catalyst activity.</p> <p> The rate of catalyst decay is expressed in an analogous manner and in particular, the conversion dependence is maintained.</p> <p> The optimal policy of choosing the temperature so as to maintain the exit conversion constant in time when catalyst decay is independent of conversion, is examined.</p> <p> The extension of this constant conversion policy to the present system is discounted.</p> <p> New optimum seeking methods are developed and numerical calculations presented to illustrate the optimal profiles.</p> / Thesis / Master of Engineering (MEngr)

<p> In contrast to the fast-paced changes and lifestyle that are endemic to modem, secular society, the Old Order Mennonites live a simple, religious life and aim to keep it that way by mediating change. How they are actively able to preserve their culture is the focus of this dissertation. The Old Order Mennonite community of Waterloo Region in southwestern Ontario, Canada served as the case study for understanding the minded aspects of social change and continuity. Fourteen in-depth, qualitative interviews were held with current and former Old Order Mennonites. A further five interviews were conducted with public school teachers and principals. Two interviews with health care providers and four interviews with members of more liberal Mennonite churches were also carried out. These additional interviews offered perspectives on the dynamics of Old Order Mennonite to non Mennonite interaction and provided general background data on the Old Order way of life. Participant-observation in participants' homes, workplaces, schools, and churches was also undertaken. </p> <p> Building on Barth's (1969) notion of social boundary maintenance and working from an interactionist perspective on social change, I argue that the key ways in which the Old Order manage change revolve around: (a) social distancing through isolation (e.g., farming, separate schooling) and insulation (e.g., technological barriers such as the continued use of the horse and buggy, distinct language, and conservative dress); (b) taking a "prescribed" approach to change such that the group's leaders control and dictate change through the Ordnung (church rules) and manage both internal issues (e.g., problems with youth) and external threats to continuity (e.g., a turbulent farm industry); and, (c) constructing and maintaining an ideology which reinforces the Old Order way of life as sacred and worthy of preservation. </p> / Thesis / Doctor of Philosophy (PhD)

<p> This thesis is an experimental study of the effects of injecting dilute polymer solutions into a turbulent boundary layer developed on a flat plate submerged in water.</p> <p> A flat plate having a plexiglass surface together with a separate leading edge piece were specially designed for observing the boundary layer phenomena. Aqueous polymer solutions were introduced into the boundary layer through a slit situated in the leading edge piece. Hot-film anemometer technique was employed in the measurements of velocity profiles, turbulence intensities and lateral correlation coefficients at several locations on the plate. The investigation was carried out for two Reynolds Numbers, based on the length of the plate, of 2.4 x 10^5 and 6.4 x 10^5. The variation in the drag force with respect to the polymer concentrations and the injection rates was assessed based on the velocity profile data. It was found that the momentum diffusivity was smaller than for pure water, and that the presence of the polymer molecules seemed to promote a more uniform distribution of the sizes of the turbulence eddies.</p> / Thesis / Master of Engineering (MEngr)

Bounded analytic functions on the open unit disk D = {z ∈ C | |z| < 1} are a fre-quent area of study in complex function theory. While it is easy to understand thebehavior of analytic functions on sequences with limit points inside D, the theorybecomes much more complicated as sequences converge to the boundary, ∂D. In thisthesis, we will explore boundary theorems, which can guarantee specific desired be-havior of these analytic functions. The thesis describes an elementary approach toproving Fatou’s Non-Tangential Limit Theorem, as well as proofs and discussion ofthe subsequent classical boundary theorems for specific points, Julia’s Theorem andthe Julia-Carathéodory Theorem. This thesis serves as a synthesis of these boundarytheorems in order to fill a gap in the overarching literature.

The behavior of animals is often complex and requires them to interact with their surroundings. Within the brain, there are specialized neural systems in place to create and store representations of space. In order to effectively utilize these spatial mappings, there must be coordination between sub-cortical systems, which are responsible for allocentric spatial processing, and cortical regions, which handle sensory processing in egocentric coordinates. The retrosplenial cortex is a candidate for the role in facilitating the transformation between different coordinates, as it is anatomically located between the hippocampus and sensory cortical areas and exhibits both egocentric and allocentric spatial responses. The first experiment explored the firing properties of neurons in the retrosplenial cortex in response to boundaries defined in egocentric coordinates. Based on previous research conducted in our lab, which showed that cells in the striatum respond to such boundaries, rats were implanted with electrodes to record the activity of neurons in the retrosplenial cortex while they roamed freely in an open field. The response properties of these neurons were analyzed as the arena was expanded, its shape altered, and boundaries were added and removed. A subgroup of neurons, referred to as Egocentric Boundary Cells, showed increased or decreased firing when the rat was at a specific distance and direction from any of the arena's boundaries. These cells showed no preference for any particular boundary, and their firing was not biased by the animal's angular velocity or turning behavior, suggesting that they respond to boundaries in a general manner, regardless of the features of the boundary or the animal's behavior. Building on experiment one, the second experiment examined the behavior of retrosplenial neurons in rats during open field exploration when alterations were made to the environment. In three separate sessions, a subset of neurons recorded showed either an increase or decrease in their mean firing rate throughout the entire session in which the environment was altered, then returned to prior levels when the environment was returned to a familiar configuration. These alterations included the introduction of an object, rotation of boundaries, expansion of boundaries, changes in the arena's geometry, and removal of boundaries. Similar proportions of neurons exhibited increases or decreases in firing rate for all experimental manipulations. Furthermore, the majority of retrosplenial neurons showed strong speed sensitivity. Some neurons showed an increase in firing rate as speed increased, others showed a decrease in firing rate as speed increased, and some had a specific speed at which their firing rate was the highest. These results support the idea that the RSC is involved in contextual and memory processing, scene processing, as well as transmitting information about self-movement to downstream regions. The third experiment analyzed the different poses of rats as they moved through open field arenas, using simultaneous high-resolution thermal, depth, and RGB cameras. This was organized into a new open-source dataset called Rodent3D. The three-dimensional posture of the animal was reconstructed from the two-dimensional videos using a model called OptiPose. We investigated aspects of the environment where the animals spent the most time looking, such as boundaries and objects, and the frequency and duration of behaviors such as rearing and changes in heading. Finally, we discuss the significance of our model and the potential uses of our unique dataset for the fields of neuroscience and computer vision, as well as future research plans. These experiments demonstrated that the retrosplenial cortex is a vital region for spatial processing, particularly emphasizing egocentric responses. We show that aspects of the environment, such as boundaries, the presence of objects, and changes to the local features induce multiple changes in spatial firing properties of neurons. We also provide a novel open-source model and dataset that provides an innovative tool for more rigorous behavioral analysis that can be used in many disciplines. Altogether, these results suggest that the retrosplenial cortex plays a crucial role as a hub for egocentric spatial processing and coordinating of spatial reference frames to support spatial memory and navigation.

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