Queen's Graduate Theses and Dissertations

This is a collection of the Queen's University Masters Degree and PhD Theses and Dissertations. Submissions are limited to officially registered Queen's University graduate students, only.


Recent Submissions

Now showing 1 - 5 of 8179
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    Seismic Performance of Bolted Glulam Timber Brace Connections with Internal Steel Plates
    Civil Engineering; Woods, Joshua; Viau, Christian
    Mass timber braced frame systems achieve their ductility through the brace connections. Canadian design standards currently lack guidance on how to detail bolted brace connections to achieve a target system-level ductility as per the National Building Code of Canada. This research aims to develop guidelines on how to detail bolted glulam timber brace connections to achieve moderate or limited ductility. To accomplish this objective, 4, 8, and 12-storey prototype buildings were designed to determine realistic brace design forces. Experimental tests were conducted on brace connections from the prototype buildings and finite element models using ABAQUS were developed to predict and compare to the experimental brace behaviour. A total of 12 brace specimens with one or two slotted-in steel plates and two different bolt sizes were studied with the aim to determine the ductility of the connections and brace assemblies. The use of self-tapping screws as perpendicular-to-grain reinforcement to prevent splitting and enhance brace ductility was also investigated. The results of the experimental study showed that both end connections in a brace can experience larger plastic deformations if the connections exhibit a post-yield hardening response. To ensure a post-yield hardening response, connections can be designed with bolt spacing greater than the minimum allowable in Canadian Wood design standards with the addition of self-tapping screws perpendicular to grain to minimize splitting. The experimental yield strengths were compared to the design yield resistance and the results showed that the design yield resistance was more accurate for connections with two slotted-in steel plates than those with only one. The results of the experimental tests were then compared to finite element models of two of the connections that were calibrated for a connection with a single dowel. The finite element models were reasonably accurate for the connection with the two slotted-in plates and less accurate for the connection with a single slotted-in plate.
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    Generative Adversarial Networks Based on a General Parameterized Family of Generator Loss Functions
    Mathematics and Statistics; Alajaji, Fady; Gharesifard, Bahman
    This thesis introduces a unifying parameterized generator loss function for generative adversarial networks (GANs). We establish an equilibrium theorem for our resulting GAN system under a canonical discriminator in terms of the so-called Jensen-$f$-divergence, a natural generalization of the Jensen-Shannon divergence to the $f$-divergence. We also show that our result recovers as special cases several GANs from the literature, including the original GAN, least square GAN (LSGAN), $\alpha$-GAN and others. Finally, we systematically conduct experiments on three image datasets for different manifestations of our GAN system to illustrate their performance and stability.
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    Light Emission and Charge Transport in Reverse Biased Polymer Junctions
    Physics, Engineering Physics and Astronomy; Gao, Jun
    A semiconductor homojunction such as a p-n junction is at the heart of many modern solid-state devices. Among organic electronic devices, light-emitting electrochemical cells (LECs) are unique in that they possess a true p-n junction formed by in situ electrochemical doping reactions. Similar to an inorganic p-n junction LED in many aspects, LECs have some very desirable device characteristics such as low operating voltage, high efficiency and high tolerance to film thickness variation. However, the LEC junction itself is still poorly understood, especially in its stable, frozen form. My research focuses on the elucidation of electroluminescence (EL) and electrical transport properties of frozen-junction polymer LECs (PLECs) made from a conjugated polymer emitter and a solid polymer electrolyte. Chapter 1 covers the basics and background of LECs, including the materials, operating mechanism and relevant theories on charge transport. Chapter 2 provides a complete account of experimental techniques and procedures used in this dissertation research. Chapter 3 uncovers the underlying mechanism of a puzzling EL phenomenon observed under reverse bias. Careful imaging and transport measurements determined that the reverse bias EL was caused by the tunnel injection and subsequent recombination of charge carriers into the dedoping "i" (intrinsic) region. In Chapter 4, the frozen PLECs were investigated for their temperature dependence. A biased dedoping scheme was used to achieve the strongest ever reverse bias EL. Temperature hypersensitivity of the reverse bias EL was discovered and explained with a recombination model taking account of carrier transit time versus recombination time in the newly formed intrinsic region. In Chapter 5, the as-formed frozen PLEC junction was subjected to a large reverse bias current at a fixed temperature. During this process, the light emission zone was observed to shift into the previously n-doped region. Optical and SEM imaging revealed that significant material loss had occurred in the process. The material loss led to the formation of electrical trees in the n-doped region. We conclude that the treeing was caused by hot electron bombardment, which also caused light emission to become cathodoluminescence. Finally, Chapter 6 provides a conclusion and some suggested directions for future work.
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    Kinesiology and Health Studies; Gurd, Brendon
    Enhancements in maximal aerobic capacity (VO2max) resulting from exercise training have garnered attention among individuals focused on exercise performance and well-being. Importantly, improvements in VO2max are associated with a considerable reduction in the risk of all-cause mortality and cardiovascular disease. Concurrently, there is considerable interest surrounding ‘individual response classification’ – comprised of various approaches that improves our understanding of individual changes in performance parameters and/or assesses exercise-induced responses across individual’s or populations. As such, this thesis attempts to address two novel questions pertaining to the field of individual response: i) what is the influence of a supramaximal verification phase during repeat measurement of VO2peak on the typical error (TE) and the response rate following exercise training? and, ii) do individual response classification for surrogate markers of CRF agree with response classification for VO2peak? Our results pertaining to question i) indicated that incorporation of supramaximal verification consistently reduced the standard deviation (SD) of individual response, typical error, and confidence interval widths. However, SDs were statistically similar across exercising and non-exercising groups (p>0.05). Response rates increased when incorporating either one (INCR1 to INCR1+; 24% to 48%, p=0.07) or two (INCR2 to INCR2+; 28% to 48%, p=0.063) supramaximal verification phase(s). Moreover, our results pertaining to question ii) indicated that changes in resting heart rate (RHR) (p=0.02, r2=0.39) and training performance (p=0.02, r2=0.36) significantly correlated with changes in VO2peak. We also observed consistently poor agreement between response classification for VO2peak and surrogate markers of cardiorespiratory fitness (CRF) with classification agreement falling below 60% for all outcomes. Therefore, our findings demonstrate that i) supramaximal verification phase reduced uncertainty when classifying individual VO2peak responses, and ii) response classification of surrogate markers of CRF demonstrate poor agreement between individual changes in VO2peak.
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    Mining Engineering
    Boron ores have distinct issues related to their sparingly soluble nature, resulting in the accumulation of undesirable levels of solubilized species spreading to the surrounding area and water contamination. The presence of arsenic sulphides such as realgar and orpiment can potentially cause even greater problems to the environment due to their toxicity. Arsenic contamination in water sources is a significant environmental issue in some regions, leading to adverse health impacts and requiring remediation measures. A detailed experimental investigation was conducted to study the fundamental surface properties of arsenic-bearing minerals. Based on the previous research on the relationship between native floatability and crystal structure, realgar and orpiment were known to be inherently hydrophobic. In this work, realgar is shown to be more hydrophobic than orpiment due to the additional role of its capacity to form elemental sulphur. Such differences were studied through the determination of wettability profiles from film-flotation experiments for arsenic-bearing minerals, but also other sulphide minerals. Although, it is an oxidation product from arsenic sulphides, arsenolite (As2O3) was found to be strongly hydrophobic, which was characterized with respect to pH and reactions with metal ions. A UV method was developed based on quantitative analysis of elemental sulphur from solvent extraction of sulphide minerals, which was correlated with their film-flotation profiles. Monoclinic pyrrhotite indicates much greater amounts of elemental sulphur on its surface than hexagonal pyrrhotite. FTIR studies provided additional support for the presence of elemental sulphur on sulphide minerals, but the quantitative correlation with film-floatability and UV studies was lacking, which was attributed to the much finer particle size range required in the KBr methodology. Micro-flotation experiments were carried out with single minerals and mixed minerals involving realgar-orpiment-arsenolite and colemanite. Micro-flotation results were in general agreement with film-flotation results. Both direct flotation and reverse flotation approaches were tested for the separation of arsenic minerals. The kerosene flotation system involving sodium silicate as a depressant for colemanite was found to be the best option for the removal of arsenic minerals.

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