UWSpace

UWSpace is the University of Waterloo’s institutional repository for the free, secure, and long-term home of research produced by faculty, students, and staff.

Depositing Theses/Dissertations or Research to UWSpace

Are you a Graduate Student depositing your thesis to UWSpace? See our Thesis Deposit Help and UWSpace Thesis FAQ pages to learn more.

Are you a Faculty or Staff member depositing research to UWSpace? See our Waterloo Research Deposit Help and Self-Archiving pages to learn more.

Photo by Waterloo staff

Communities in UWSpace

Select a community to browse its collections.

Recent Submissions

  • Thumbnail Image
    Item type: Item ,
    Evaluating Face Mask Efficiency on Children and Adults
    (University of Waterloo, 2025-12-05) El Khayri, Hicham
    Small infectious aerosols have been a major vector for the spread of diseases such as COVID-19 and influenza. During the recent global pandemic, masking played a key role in reducing airborne transmission, although significant variability has been noted in the ability of different mask types to limit pathogen-laden aerosol dispersion and inhalation. Moreover, there remain significant gaps in the literature regarding mask performance for children. The aim of this thesis is to characterize mask inward protection efficiency for both children and adults, and source control efficiency for children in the 0.2 μm to 1 μm particle size range. An approach based on the conservation of mass guided the experimental methodology used to estimate mask filtration characteristics. For all tested masks, the material filtration efficiency was measured to be at or near 100%, whereas fitted filtration efficiencies for both source control and personal protection were significantly lower. This disparity underscores the highly degrading effects of leakage from gaps at the mask-face interface. Inward protection efficiency of N95, KN95, and surgical masks donned regularly and using the tie and tuck method were estimated on a medium NIOSH adult head form. The tested N95 barrier provided the greatest protection, followed by the KN95 respirator, while the surgical masks offered the least protection. Use of the tie and tuck for surgical masks method yielded only a small, statistically insignificant improvement in inward protection compared to regularly worn variants. Incorporating results from broader literature, mean inward protection efficiency ranges of [67.9%,100%] and [12.5%,79.6%] were determined for the N95 and regularly worn surgical masks, respectively. Both inward protection and apparent filtration efficiencies of adult, modified adult, and child variants of the KN95, CA-N95, and surgical mask as well as the N95 respirator, were estimated on a child manikin. Results further underscore the critical importance of proper fit to mask performance. Child-sized respirators provided higher source control and personal protection compared to other barriers tested. In contrast, the adult-sized surgical mask, which exhibited a loose fit on the child manikin, demonstrated poor performance in both metrics due to the highly degrading effects of leakage. Overall, whenever both variants are available, adult-sized masks demonstrate markedly reduced fitted efficiencies on the child manikin relative to child-sized variants, attributed to larger gaps at the mask-face interface. Flow visualization of air exhaled through the tested barriers qualitatively corroborated these findings, revealing substantially reduced leakage for child-sized variants compared to adult-sized equivalents. Given the increased sensitivity of children to mask breathing resistance, pressure differentials measured across masks donned on the child head form provided relative indicators of breathability. Results demonstrated that masks with similar filtration efficiency can exhibit significant differences in breathability. For example, the child-sized CA-N95 achieved equal or greater fitted filtration efficiency while consistently maintaining lower pressure drops compared to the child KN95. In fact, KN95 respirators showed differential pressures greater than or equal to those of all other tested masks. For a given mask type, better fit was associated with higher differential pressures. However, across different mask designs, higher filtration efficiency did not necessarily compromise breathability.
  • Thumbnail Image
    Item type: Item ,
    FROM THE MOUTHS OF HUNTERS: HUNTER PERCEPTIONS IMPROVE UNDERSTANDING OF THE RELATIONSHIP BETWEEN HUNTERS AND CONSERVATION IN CANADA
    (University of Waterloo, 2025-12-05) Basdeo, Maya
    As a group of nature-based outdoor recreationists, hunters in Canada are not well understood, particularly in the context of their role in conservation. Hunters in Canada are not typically equated with being conservation actors, however there is a dearth of current academic literature that addresses the relationship between hunting and conservation in Canada and thus hunters may not accurately be represented within conservation circles. Collaboration between different groups of conservationists could be improved, and gaining a better understanding of how hunters perceive their place in conservation may contribute to greater unity around issues of conservation concern. The research question I explored was “Do hunters in Canada perceive they contribute to conservation, and if so, in what ways?”. I used an anonymous online questionnaire to survey hunters across Canada using Qualtrics as the survey tool. The survey link was distributed through six provincial and territorial hunting-conservation organizations affiliated with the Canadian Wildlife Federation: Ontario Federation of Anglers & Hunters, Manitoba Wildlife Federation, Saskatchewan Wildlife Federation, Alberta Wildlife Federation, B.C. Wildlife Federation, and Yukon Fish & Game Association. The survey consisted of 23 questions and was conducted over a six-week period in the fall of 2023. 4022 valid responses were received from every province and territory, with the majority from Ontario. Four key themes emerged from the survey results of hunters in Canada: hunters identified more strongly as conservationists than as hunters, hunters identified numerous ways in which they participate in and support conservation, hunters are political actors, and hunters can be allies for conservation. Focusing on hunter perceptions was a necessary first step in exploring the relationship between hunters and conservation in Canada. The breadth of these results highlight opportunities for further empirical research and the need for more research to be conducted in Canada on this topic.
  • Thumbnail Image
    Item type: Item ,
    Quantum Fields in Curved Spacetimes: From Detector Entanglement to Black Hole Thermodynamics
    (University of Waterloo, 2025-12-05) Bhattacharya, Dyuman
    This thesis presents two independent investigations into quantum field theory in curved spacetime. The first concerns relativistic quantum information, with a focus on entanglement harvesting and detector-based probes of quantum fields in curved spacetimes. The second addresses semiclassical aspects of black hole thermodynamics in AdS braneworld settings, incorporating the backreaction of quantum fields to all orders of perturbation theory, and extending previous studies of quantum black holes to include both charge and spin. In Part I, we study the entanglement of quantum fields in curved spacetime, using localized particle detectors interacting with a scalar field. We analyze scenarios involving both flat and curved backgrounds, including gravitational shock waves, the BTZ black hole, and general dimensional anti–de Sitter and de Sitter spacetimes. For the case of initially entangled detectors, we find that interactions with the field can lead to either degradation or amplification of entanglement, depending on the initial state and spacetime geometry. We further derive exact expressions for density matrix elements, at the lowest perturbative order, in the form of infinite analytical series, for detectors on static worldlines in various spacetimes. The transition rate of an in-falling detector in the BTZ black hole spacetime is also derived as an infinite series. These analytic results allow for exact evaluation of quantities, namely the entanglement measures of concurrence and negativity, which are typically computed numerically. In addition, we provide a new example of the ability of detectors to distinguish topologically distinct spacetimes which are locally identical outside of horizons, focusing on the ℝP² and Swedish geons built from the BTZ spacetime. Our results show that localized measurements are sensitive not only to curvature but also to topological features of the underlying geometry. Part II is concerned with the construction and thermodynamic analysis of quantum-corrected black holes in a doubly holographic braneworld model. We obtain a charged and rotating solution localized on an AdS₃ brane embedded in an AdS₄ bulk, incorporating the full backreaction from conformal fields to all orders of perturbation theory. We compute the thermodynamic properties of these black holes, and examine their behavior in extended thermodynamic phase space where the cosmological constant is a variable. We find that the inclusion of charge or spin removes re-entrant phase transitions present in the neutral-static case, and that the critical exponents of these objects match those predicted by classical mean-field theory. The re-entrant phase transitions of the neutral-static quantum black hole has critical exponents which differ from the mean-field values
  • Thumbnail Image
    Item type: Item ,
    Woodland ecosystem services of the past and present in Herstmonceux and South England
    (University of Waterloo, 2025-12-05) Pita, Katie
    This thesis quantifies ecosystem services from broad- and mixed-leaved woodlands in the southern United Kingdom. Synthesizing concepts and approaches from historical ecology, environmental history, community ecology, dendrological allometry, and punctuated equilibrium theory, this thesis illuminates the multifaceted ways in which woodlands provide ecosystem services that are valued by people in the UK, both socially and ecologically. A complex relationship between people and woodlands emerges through time, which can be understood directly via management decisions, but also more abstractly through the sentiments that people attach to trees. Both of these approaches carry normative implications about the value of particular woodland ecosystem services. While the values that guided past decisions in woodland management are not always explicit, archival maps and remotely sensed data can reveal the nature of land use changes that manifest over long periods of time, i.e., 150 years. Within a case study context in Herstmonceux, East Sussex, archival data demonstrated a progression towards a modern day multifunctional wooded landscape. Within this modern context, historical woodland management regimes like coppicing drive specific ecosystem services like biodiversity and carbon storage to change measurably on a near-annual basis. This indicates that historic management regimes have important implications for ecosystem service provision not just over the course of generations, but also on fairly short time frames, e.g., 15 years. Land managers of coppice woodlands must therefore be cognizant of how everyday land management decisions can impact the ecosystem services, and therefore values (both intrinsic and instrumental) derived from them. Importantly, land management decisions and regimes also change abruptly in response to exogenous factors. When extreme damage was caused to trees and woodlands as a result of the October 1987 Great Storm, there occurred a traceable punctuation reflected in both the public sentiment and the priorities of woodland managers regarding trees. Changes in woodland ecosystem services can thus be slow-moving or sudden. Ultimately, it is this complex, always-changing relationship between humans and the environment that shape not only the actual provision of ecosystem services, but also perceptions of that provision, and, furthermore, how ecosystem services themselves are valued. The ecosystem services perspective, therefore, may be applied to and represent both intrinsic and instrumental values, rather than solely instrumental values, which has been a longstanding critique of the framework. However, researchers aiming to employ the ecosystem services framework in this manner must be intentional and explicit in their doing so, in order to shift the guiding paradigms in conservation away from “nature for people,” and towards a “people are nature” perspective.
  • Thumbnail Image
    Item type: Item ,
    An Experimental-Cohesive Zone Model Approach to Predict Fatigue Life of Adhesive Joints with Varying Modes of Loading and Joint Configurations for Automotive Applications
    (Taylor & Francis, 2024-10-03) Ibrahim, Ahmed Hanafy; Watson, Brock; Jahed, Hamid; Rezaee, Saeid; Cronin, Duane
    Predictive fatigue life models of adhesive joints are necessary to enable the assessment of automotive bonded structures while reducing costly experimental testing. However, contemporary models have typically been calibrated for specific joint configurations and modes of loading, limiting their applicability to large-scale structures. Additionally, available models are based on simulation of cumulative fatigue cycling, making them computationally prohibitive. In the current study, fatigue experimental tests were undertaken on adhesive joints in cross-tension (CT) (load angles of 0°, 45°, and 90°) and single-lap shear joint (SLJ) configurations. A total of nine joint configurations, having symmetrical (same material and thickness) and asymmetrical (dissimilar material or unequal thickness) joints, were tested. Fatigue tests at load levels between 25-75% of the static peak load were performed until joint failure or to runout (two million load cycles). The static tests of the joints were simulated to failure using finite element (FE) models with the cohesive zone method (CZM). The maximum fracture energy release rates (Gmax) were calculated within the adhesive bond line at static loads corresponding to the peak loads of the fatigue tests. The Gmax values, computed from single cycle, specimen-specific FE simulations, were correlated with the measured fatigue life (Nf) of the adhesive joints with varying modes of loading and joint configurations. The fatigue life prediction model, based on Gmax − Nf correlation, predicted the cycles to failure for 85% of the fatigue tests, and 81% of the independent validation tests. The proposed fatigue life prediction approach provides computational efficiency and large-scale compatibility.