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Surface Currents in Chiral P-Wave SuperconductorsAshby, Phillip E. C. January 2008 (has links)
<p> It is believed that Sr2RuO4 is a triplet superconductor that breaks time reversal symmetry, and it is expected to have spontaneous magnetization both at the sample edge, as well as at domain walls. Recent magnetic microscopy results place upper limits on the magnetic fields differing from previous theoretical calculations by 2 orders of magnitude. Using a Ginzburg-Landau formalism we investigate the effects of a rough surface as well as parameter choices which differ from the typical weak coupling parameters on the magnitudes of the spontaneous supercurrents and magnetic fields. The dependance on surface roughness is found to be small resulting in only a 20% reduction for the weak coupling parameters. Changing the parameters from weak coupling in addition to pair breaking surface effects is also found to affect the magnitudes of the spontaneous fields weakly, except in certain unphysical parameter regimes. The effects of the surface stabilizing another non-magnetic
order parameter are considered, and give rise to field distributions with similar features to those present at domain walls.</p> / Thesis / Master of Science (MSc)
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Stored-grain Monitoring Utilizing Radio Wave ImagingAsefi, Mohammad 20 June 2016 (has links)
Storage of large amounts of grain post-harvest is common during drying, distribution and preservation of crops. During storage, where grain is usually held in a large metallic container or bin, changes in temperature, moisture, and insect infestation can cause grain to spoil annual post-harvest crop losses are estimated up to 30% in some countries while Canadian losses of 2% exceed a billion dollars. Currently, locally-sensitive temperature and moisture sensors are a common way to monitor grain bins. Sensors are generally strung on heavy duty cables that can withstand the forces generated when unloading grain. This monitoring method provides a coarse sampling of the storage environment due to system cost and the fact that using many sensor cables would require significantly reinforcing the bin. Further, these cables are not suitable for monitoring stored crops that are dried by a combination of stirring and aeration.
Over the past four years, I have developed multiple electromagnetic imaging based grain-monitoring systems with the goals of overcoming the deficiencies of existing sensor technology and allowing farmers and distributors a robust way to preserve our food stores and increase revenue. The proposed technology aims to produce global, quantitative images of grain properties throughout the bin from measurements taken by a few side-mounted antennas used to interrogate the bin contents.
To develop this technology intensive research was put into the design of low profile, robust antennas as well as numerical analysis of the effects of different field distributions within conducting boundaries. Both electric and magnetic field sensitive antennas were built and tested in small lab-scale as well as full-scale grain bins to experimentally evaluate the performance of such imaging system. This thesis provides details on different system designs and analysis and describes the advantages and challenges associated with the techniques described. / October 2016
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Influence of Surface Currents in the Dispersal Pathways of Eggs of Cubera Snapper, Lutjanus cyanopterus (Cuvier, 1828), at a Spawning Aggregation Site at Gladden Spit, BelizeMendez-Jimenez, Adriana 2012 August 1900 (has links)
Most large reef fish use a migratory reproductive strategy and tend to spawn in aggregations that occur at predictable locations and times. Though numerous hypotheses have been formulated to explain the reasons behind this phenomenon, there remain few data to evaluate the relative merits of various hypotheses. Oceanographic variables and lunar cycles are believed to drive the timing and location of this reproductive strategy. However, the dynamics of the interaction between coastal currents, water temperature, biomass concentrations, spawning site selection and gamete transport are still unclear. This study aimed to examine the influence that currents exert on gametes released at spawning aggregations of Cubera snapper Lutjanus cyanopterus (Cuvier, 1828) at Gladden Spit, Belize. It was hypothesized that surface currents flowed offshore at the time and location of spawning. However, observations from this study, using Lagrangian and Eulerian methods, indicated that eggs most likely travel westerly towards the reef and into the reef channel. The dispersal rate of eggs appeared to be explained by a power relationship, with buoyant fertilized eggs dispersing horizontally such that the area of the spawning cloud increased with time. Egg density within the spawning cloud generally decreased over time as it dispersed with the predominant surface currents. Most importantly low-cost surface drifters area an appropriate, highly replicable way to monitor surface ocean currents at spawning sides in areas where more sophisticated methods are not available. Understanding how abiotic factors influence the occurrence of multispecies spawning aggregations will lead to better conservation and management strategies in the Western Caribbean.
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