Eddy current separation aims to recover non-ferrous metals from non-metals utilizing electromagnetic interactions. In order to describe the separation process, a representative model is needed that can accurately calculate the induced forces. Such a model can be used to optimize the efficiency of current equipment as well as designing ones that can offer new capabilities. Models proposed so far for the separation process, using traditional approaches to calculate forces, had limited success due to complex nature of electromagnetic interactions. In this dissertation, a novel method for calculating the magnetic force acting on non-ferrous metal particles was developed. By this method, force calculations can be carried out accurately using intrinsic parameters of particles such as size and shape, as well as its orientation within the field. The method also takes into account the operating parameters of the equipment such as the rotational speed of the magnetic element and the speed of the belt. In order to verify this method and collect empirical data, a novel data acquisition and interpretation approach was developed. A computer simulator was also developed that can calculate trajectories of particles based on operating parameters of the eddy current separator and characteristics of the material being processed. The accuracy of the simulator was verified using empirical data obtained by the novel data acquisition method. This contribution provides a viable option for reducing the cost of analyzing; optimizing and designing eddy current separators. / PHD

With the increased application of large eddy simulations and hybrid Reynolds-averaged Navier-Stokes techniques, the generation of realistic turbulence at inflow boundaries is crucial for the accuracy of numerical results. In this dissertation research, two novel turbulence inflow generation methods are derived and validated. The first method, the Triple Hill's Vortex Synthetic Eddy Method, is a new type of synthetic eddy method, where the fundamental eddy is constructed through a superposition of three orthogonal Hill's vortices. The amplitudes of the three vortices that form the fundamental eddy are calculated from known Reynolds stress profiles through a transformation from the physical reference frame to the principal-axis reference frame. In this way, divergenceree anisotropic turbulent velocity fields are obtained that can reproduce a given Reynolds stress tensor. The model was tested on isotropic turbulence decay, turbulent channel flow, and a spatially developing turbulent mixing layer. The Triple Hill's Vortex Synthetic Eddy Method exhibited a quicker recovery of the desired turbulent flow conditions when compared with other current synthetic turbulence methods. The second method is the Control Forced Concurrent Precursor Method which combines an existing concurrent precursor method and a mean flow forcing method with a new extension of the controlled forcing method. Turbulent inflow boundary conditions are imposed through a region of body forces added as source terms to the momentum equations of the main simulation which transfer flow variables from the precursor simulation. Controlled forcing planes imposed in the precursor simulation, allow for specific Reynolds stress tensors and mean velocities to be imposed. A unique feature of the approach is that the proposed fluctuating flow controlled forcing method can be applied to multiple fluctuating velocity components and couple their calculation to amplify the existing fluctuations present in the precursor flow field so that prescribed anisotropic Reynolds stress tensors can be reproduced. The new method was tested on high and low Reynolds number turbulent boundary layer flows, where the proposed fluctuating flow controlled forcing method greatly accelerated the development of the turbulent boundary layers when compared with cases without controlled forcing and with only the original controlled forcing.

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<p>Forest ecosystems are a significant component of the global carbon (C) cycle. Afforestation is considered a cost-effective and ecologically viable means to sequester atmospheric carbon. However, afforestation requires intensive management practices, including thinning, to maintain and enhance the carbon sequestration capability of the forest. This study examines thinning effects on forest carbon dynamics using eddy covariance (EC) methods. In January 2012, a 74-year-old white pine (<em>Pinus strobus</em>) plantation located in southern Ontario was selectively thinned. Approximately 30% of trees, equating to 2308 m³ of wood (sawlogs and pulpwood), were removed to improve light, water and nutrient availability for remaining trees. Fluxes of energy, water, carbon dioxide (CO₂) as well as meteorological variables were measured throughout the year following thinning and compared to data from the previous 9 years to evaluate effects of thinning on forest carbon dynamics. Mean annual net ecosystem productivity (NEP), gross ecosystem productivity (GEP) and ecosystem respiration (RE) from the 9 years prior to thinning were 290, 1413 and 1118g C m^-2<strong>,</strong> respectively. Post-thinning NEP, GEP and RE were 154, 1509 and 1350 g C m<strong>^-</strong>²<strong> </strong>year^-1, respectively. Post-thinning NEP was significantly less than pre-thinning at the annual time scale due to higher RE, however post-thinning fluxes were still within the range of interannual variability. At this site, approximately 20% of interannual variability in NEP, GEP and RE was explained by environmental conditions. Effects of extreme weather events, particularly heat and drought stress, were demonstrated to negatively impact NEP. Biotic responses to environmental drivers explained the remaining 80% of interannual variability in fluxes. Thinning did not significantly impact these responses. Further, results suggest that thinning may improve tolerance to drought stress by improving water availability for remaining trees. Therefore, thinning has the potential to effectively reduce resource competition and stimulate growth and carbon sequestration in temperate coniferous forests.</p> / Master of Science (MSc)

<p>Northern boreal peatlands represent a globally significant carbon pool that are at risk of drying through land-use change and projected future climate change. The current ecohydrological conceptualization of peatland response to persistent water table (WT) drawdown is largely based on short-term manipulation experiments, but where the long-term response may be mediated by vegetation and microtopography dynamics. The objective of this thesis is to examine the changes to peatland evapotranspiration, soil physical properties, and moisture stress in response to a long-term WT manipulation. The energy balance, hydrology, vegetation, and soil properties were examined at three adjacent peatland sites in the southern sub-boreal region which were subjected to WT manipulations on the order of ±10 cm at two treatment sites (WET, and DRY) compared to the reference site (INT) as a result of berm construction in the 1950s.</p> <p>Sites with an increasing depth to WT were found to have greater microtopographic variation and proportion of the surface covered by raised hummocks. While total abundance of the major plant functional groups was altered, species composition and dominant species of vascular and non-vascular species within microforms was unaltered. Changes in vegetation and microtopography lead to differences in albedo, surface roughness, and surface moisture variability. However, total ET was only significantly different at the WET site. Transpiration losses accounted for the majority of ET, where LAI best explained differences in total ET between sites. Surface moisture availability did not appear to be limiting on moss evaporation, where lab results showed similar moisture retention capacity between microforms and sites, and where low surface bulk density was shown to be a strong controlling factor. Modelling results further suggested that, despite dry surface conditions, surface moisture availability for evaporation was often not limited based on several different parameterizations of peat hydraulic structure with depth.</p> / Doctor of Philosophy (PhD)