Geography

Aeolian transport of sand particles is an important geomorphic process that occurs over a significant portion of the earth's land surface. Wind tunnel simulations have been used for more than 75 years to advance the understanding of this process; however, there are still several principles that lack validation from direct sampling of the sand particles in flight. Neither the three-dimensional dispersion of, nor the momentum carried by particles in flight have been properly measured. This has resulted in the inability to validate numerical particle dispersion models and the key boundary-layer momentum partitioning model that serves as the framework for understanding the air-sand feedback loop. The primary impediment to these measurements being made is a lack of tools suited for the task. To this end, this PhD aims to improve existing particle tracking technology, thus enabling the collection of particle measurements during wind tunnel experiments that would address the aforementioned knowledge gaps.

Through the design and implementation of the Expected Particle Area Searching method, a fully automated particle tracking velocimetry system was developed with the capability to measure within ½ grain diameter of the bed surface under steady state transport conditions. This tool was used to collect the first 3-D data set of particle trajectories, from which it was determined that a mere 1/8th of sand transport is stream aligned and 95% is contained within ± 45o of the mean wind direction. Particles travelling at increasing spanwise angles relative to the stream aligned flow were found to exhibit different impact and ejection velocities and angles. The decrease in the number of particles with increasing height in the saltation cloud, very close to the bed is observed to transition from a power to a linear relation, in contrast to previous literature that observed an exponential decay with coarser vertical resolution.

The first direct measurements of particle-borne stress were captured over a range of wind velocities and were compared with earlier fluid stress measurements taken using Laser Doppler Anemometry. In support of established saltation theory, impacting particle momentum is found to contribute strongly to particle entrainment under equilibrium conditions. In opposition to established theory, however, particle-borne stress was found to reach a maximum above the surface and does not match the change in air-borne stress with increasing distance from the surface. Near surface splashed particles, measured herein for the first time, appear to play a greater role in stress partitioning than previously thought. This study suggests that research is needed to investigate the role of bed load transport on stress partitioning, to differentiate between airborne trajectory types, and to develop particle tracking tools for field conditions.

Author Keywords: Aeolian Transport, Eolian Transport, Particle Tracking Velocimetry, Saltation, Stress Partitioning, Wind Tunnel Simulation

Since 1984, poetry slams have emerged as a politicized expressive movement of performing the personal and political through poetry competitions. Slams are also discursively spatialized, often represented as "spaces" that are "safe," "inclusive," etc. In this thesis, I investigate how, why, and to what effect the Peterborough Poetry Slam produces, consolidates, and challenges such "resistant spaces." Drawing on interviews and participant observation, I consider how the slam's reiterative practices facilitate its space-making by encouraging performances that resist, reimagine, and sometimes inadvertently reify dominant societal norms. I argue that this space-making is imperfect yet productive: though not resistant space in any straightforward or static way, the slam continuously produces possibilities to challenge norms and confront power. This thesis contributes to scholarship on performative space and creative resistance movements. In an era when political resistance to power structures is often silenced, this research offers insights of potential significance to other resistant space-makings.

Author Keywords: Nogojiwanong Peterborough, performative space, poetry slam, resistance, space-making, spoken word