This project investigated the manufacturing of large diameter welded PTFE rings.This welding process is time consuming and can take over ten hours for one complete weld cycle. Additionally, the welds can have poor quality in the center of the material due to insufficient heating across the weld face. The goal of this research was to address these two issues by analyzing the current process to determine the root cause of weld failures while also determining the feasibility of reducing the weld cycle time. The scope of this thesis was to develop a model to better understand and simulate the current process which could then be used for design future improvements.<div><br></div><div>A MATLAB model of the current process was developed to simulate the transient heating cycle of the most common weld cycle for PTFE currently used by a manufacturer of PTFE seals. The data for the material properties was gathered from the manufacturer test data as well as from Lau et al. (1984). Temperature dependent material properties were used in the program because the PTFE is heated above its melting point during the weld cycle. Because of the complexity of this heat transfer problem, the heat flux in the model was tuned so that it accurately reflected the current process. This is because the goal of this study was not to determine the exact heat fluxas it was unknown, but to develop an accurate model. Thus, the heat flux was assumed and the model was then verified with process data. Results from the model were compared to validation results from a FLIR thermal camera. The model predicted the compared temperatures to within 3.1% error at both 15-minute and 90-minute intervals. Though there are many potential sources of error in the process and the thermal camera measurement, the model was deemed acceptable as a model of the current process. A semi-infinite heat analysis was calculated to simulate a hot plate welding method on the PTFE. This showed that the temperature of the weld face could be raised by 57.275°C. It is believed that a method similar to hot plate welding applied to PTFE could heat the material faster and more evenly than the current process, reducing the weld failures and cycle time.<br></div>

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The threespine stickleback (Gasterosteus aculeatus) is an important model for studying evolution. Sticklebacks are widely distributed in the northern hemisphere and inhabit freshwater, brackish, and marine waters. Anadromous and marine populations (hereafter marine) are assumed to be homogenous in space and invariant in time in their phenotypic characteristics, despite marine environments varying on regional and local scales. Recent studies suggest there is in fact genetic and phenotypic structure in marine sticklebacks, yet the ecological causes remain unclear. My goal was to assess trait variation in marine stickleback populations around Southern coastal British Columbia (BC), and to determine whether or not oceanographic and habitat characteristics explained this variation. The area around Vancouver Island was ideal because four distinct oceanographic regions surround the island with varying coastal habitat types. Between May-July 2019, I sampled ~600 sticklebacks from 15 sites. I then characterized trait variation using two-dimensional (2D) geometric morphometric analysis to compare individuals between oceanographic regions and coastal habitats. I focused on five traits: armour phenotype, head size, body size, head shape, and body shape. I chose these traits because they are ecologically important and well-studied in freshwater populations, where their ecological drivers are known. I found that marine sticklebacks did vary morphologically among and between regions and habitats, but the variation was not immediately related to environmental variation, nor obviously comparable to variation in freshwater populations. Sexual dimorphism was the largest source of variation in the data, a well-established finding. But oceanographic and habitat variables influenced differences between males and females. I concluded that marine sticklebacks offer abundant opportunities for expanding our knowledge of drivers of morphology in nature. / Graduate / 2022-04-11

Flight data recorders (FDRs) play a critical role in determining root causes of aviation mishaps. Some aircraft record limited amounts of information during flight (e.g. T-1A Jayhawk), while others have no FDR on board (B-52 Stratofortress). This study explores the use of image-based flight data acquisition to overcome a lack of available digitally-recorded FDR data. In this work, images of cockpit gauges were unwrapped vertically, and 2-D cross-correlation was performed on each image of the unwrapped gauge versus a template of the unwrapped gauge needle. Points of high correlation between the unwrapped gauge and needle template were used to locate the gauge needle, and interpolation and extrapolation were performed (based on locations of gauge tick marks) to quantify the value to which the gauge needle pointed. Results suggest that image-based flight data acquisition could provide key support to mishap investigations when aircraft lack sufficient FDR data.

The first part of the thesis includes examining inorganic/organic hybird layered solids, also termed “clay mimics.” Transmission and scanning electron microscopy techniques were used to characterize particles before and after intercalation of pyridine based groups. The particle sizes, shape, and surface morphology were studied for a control and five intercalated species, and evidence for change in particle size and shape was found. The second part of the thesis involves a study in the area of inorganic-organic perovskite networks. Variations in the nature of the cationic organic portion as well as the divalent metal halides have been used to try to better predict the type of network formed. In the work reported here, metal halide and ortho-substituted anilines are combined to relate metal halide network dimensionalities to the steric demands of the ortho- substituents on aniline species. The study involved divalent d10 metal halides, and the halides used were: chloride, iodide, and bromide. The anilines used had varied substituents ortho- to the ammonium group, in order to encompass a wide range of substituents. The goal of the study was to determine if the nature of the ortho-substituent caused consistent effects on the resulting crystal structure. Crystals were grown using slow evaporation techniques and viable crystals were characterized using single crystal X-ray diffraction.

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No / The paper presents a 2-D large eddy simulation (LES) modelling approach to investigate the properties of the plunging waves. The numerical model is based on the smoothed particle hydrodynamics (SPH) method. SPH is a mesh-free Lagrangian particle approach which is capable of tracking the free surfaces of large deformation in an easy and accurate way. The Smagorinsky model is used as the turbulence model due to its simplicity and effectiveness. The proposed 2-D SPH-LES model is applied to a cnoidal wave breaking and plunging over a mild slope. The computations are in good agreement with the documented data. Especially the computed turbulence quantities under the breaking waves agree better with the experiments as compared with the numerical results obtained by using the k- model. The sensitivity analyses of the SPH-LES computations indicate that both the turbulence model and the spatial resolution play an important role in the model predictions and the contributions from the sub-particle scale (SPS) turbulence decrease with the particle size refinement.

Deployment of antenna arrays is a very promising solution to reduce the Multiple Access Interference (MAI) from high data rate users in the Wideband Code Division Multiple Access (W-CDMA) system. Combining the antenna array with a RAKE receiver, both of which exploits multipath diversity, can significantly improve the system performance. In this research, we investigate the performance of these beamformer-RAKE receivers, also known as two-dimensional (2-D) RAKE receiver, for the reverse link of the W-CDMA system. We consider three different Pilot Symbol Assisted (PSA) beamforming techniques, Direct Matrix Inversion (DMI), Least-Mean Square (LMS) and Recursive Least Square (RLS) adaptive algorithms. Two different Geometrically Based Single Bounce (GBSB) statistical channel models are considered, one, which is more suitable for array processing, and the other is conductive to RAKE combining. The performances of the 2-D RAKE receivers are evaluated in these two channel models as a function of the number of antenna elements and RAKE fingers. It is shown that, in both the cases, the 2-D RAKE receiver outperforms the conventional RAKE receiver and the conventional beamformer by a significant margin. Also, the output SINR expression of a 2-D RAKE receiver with the general optimum beamformer is derived. / Master of Science