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 ,
    Implications of a changing climate in coastal Labrador for caribou and their forage
    (University of Waterloo, 2026-02-17) Lauriault, Patrick
    The majority of Labrador’s coastal lands are below the 60th latitudinal parallel. Even so, the cold Labrador Sea currents, late-lasting sea ice, and frequent high winds, these coastal ecosystems often resemble Arctic and Subarctic ecosystems that are further north. Historically, these landscapes exhibited stunted shrub growth, but as the climate changes, the shrinking sea ice season and the cooling effects of coastal sea ice on nearby landscapes begin to subside, shrubs are now overtaking tundra vegetation communities. These shrubs threaten ground lichen communities in coastal regions. Understanding changes in vegetation allows us to predict changes in the forage available to caribou, a culturally and ecologically significant species in Labrador and other northern regions. Caribou tend to rely heavily on lichen in the wintertime to meet their dietary needs. In this dissertation, I addressed three main research questions: 1) How much lichen forage do caribou need to satisfy their energetic needs over winter? 2) With the state of ground lichen availability at three Labrador sites, what caribou density can be sustainably achieved at each location? 3) With climate change increasing coastal fog, how will lichen productivity respond to fog as a source of hydration? I used a time-series simulation to estimate caribou energetics over winter. After the simulation results, I assessed the state of ground lichen at three sites in coastal Labrador. The combined results are used to determine a sustainable caribou density at each location based on available winter forage. The caribou energetics simulation results showed that the average caribou must eat 1330 kg of lichen over the winter to avoid weight loss. The ground lichen estimates in open tundra at each of the three sites were 0.66 kg/m2 in Pinware (caribou free site), 0.1 kg/m2 in Cartwright (Mealy Mountain caribou) and 0.04 kg/m2 in Nain (George River caribou herd). With current lichen biomass estimates and an assumed 5% annual growth rate, I was able to derive sustainable caribou densities at each of the three sites (Pinware: 24 caribou/km², Cartwright: three caribou/km², Nain: one caribou/km²). I also studied how lichen productivity may be impacted by increased fog-based precipitation. Although lichens cannot compete vertically with shrubs, they may respond to climate change by becoming more productive when using fog water to increase growth in the growing season. Lichens readily use non-rainfall sources such as fog for their metabolism. Using a simulation model for lichen metabolism, I found that fog can encourage productivity in lichens, with my model showing a carbon uptake of 20 g on a 1 m2 ground lichen mat over four months from only observed fog events. Other promising findings from this study show that fog events happen much more frequently in the morning, hydrating the lichens before peak solar radiation. That fog alone will not block enough sunlight to achieve net photosynthesis. However, some troubling findings are that warmer months result in lower lichen productivity due to fog, as respiration begins to outpace photosynthesis at warmer temperatures. Fog water deposition is likely to increase in these environments, potentially altering lichen productivity in the north. Bottom-up constraints to caribou herds, such as a lack of forage, are essential to identify. Considering other threats caribou face can help herd managers and Indigenous people, who rely on caribou for a food supply, determine when intervention is required in a changing northern environment.
  • Thumbnail Image
    Item type: Item ,
    Fracture Characterization and Damage Accumulation Modelling of DP1180 Steel under Proportional and Non-Proportional Loading
    (University of Waterloo, 2026-02-17) Jeyranpourkhameneh, Farinaz
    Lightweighting remains a primary objective in the automotive industry, driven by the need to reduce fuel consumption and greenhouse gas emissions while meeting stringent crashworthiness standards. Advanced High Strength Steels (AHSS), such as Dual Phase 1180 (DP1180), have gained prominence due to their excellent strength-to-weight ratio. However, their complex fracture behavior under multiaxial and non-proportional loading conditions presents challenges for accurate failure prediction in structural simulations. This thesis aims to address these challenges through a systematic experimental investigation and modelling framework tailored to the fracture and damage response of DP1180 steel. The first phase of this work investigates the influence of gauge length on fracture strain in shear-dominated specimens. Conventional Digital Image Correlation (DIC) techniques were refined to enhance local strain measurement accuracy, focusing on strain localization in the shear zone. A series of tests were performed using butterfly shear specimens with varying gauge lengths to assess the lengthscale sensitivity of fracture strain. The results confirmed a strong dependence of measured fracture strain on the gauge geometry, reinforcing the need for standardized specimen design and DIC post-processing protocols. An optimized experimental configuration and robust DIC-based post-processing strategy were established to ensure consistent strain measurements for subsequent studies. The second component focuses on fracture under proportional loading conditions using uniaxial tension tests. Multiple specimen geometries were employed, including standard dogbone and notched samples, as well as conical hole expansion tests, to evaluate the fracture behavior of DP1180 under various constraints. Since fracture initiation under uniaxial tension is complicated by post-necking deformation, post-mortem surface strain analysis was performed to estimate local fracture strains. The study provided a reliable set of fracture strains for proportional loading conditions, allowing for direct comparison between different geometries and stress states. These results form the baseline for calibration and validation of fracture models under simple loading histories. The third phase of the work extends the investigation to combined loading paths involving simple shear and uniaxial tension. This approach enabled the evaluation of fracture behavior under intermediate stress states between pure shear and uniaxial tension. The resulting force-displacement responses and post-mortem strain measurements were used to validate the predictive capability of an existing phenomenological fracture model without necessitating re-calibration. The observed agreement between simulation and experiment under these combined stress states provides a robust validation of the model and highlights the versatility of the butterfly test methodology. To further extend the applicability of the framework, a novel experimental approach was developed to characterize fracture under non-proportional (bi-linear) loading paths. In this methodology, specimens were subjected to controlled proportional loading, after which miniature fracture specimens were extracted along different orientations and stress states. These samples were subsequently tested to failure, capturing the influence of pre-straining on fracture response. The collected data enabled an assessment of existing damage accumulation models under realistic forming conditions. Comparison with model predictions revealed that strain path changes significantly affect fracture strain evolution, especially for loading sequences that cross between tension- and shear-dominated states. These findings demonstrate the limitations of path-independent fracture criteria and underscore the importance of incorporating load history effects into damage modelling strategies. Overall, this thesis presents a comprehensive experimental framework for fracture characterization of AHSS under a wide range of loading conditions. The key contributions include: (1) development of a reliable shear fracture testing methodology that quantifies gauge-length sensitivity in DIC-based strain measurements, demonstrating variations in measured fracture strain depending on the selected length scale, (2) resolution of fracture strain identification under uniaxial tension through the combined use of multiple specimen geometries and post-mortem surface strain analysis, enabling the construction of a consistent proportional fracture dataset across a range of stress triaxialities, (3) validation of a phenomenological fracture model under combined shear–tension loading paths without re-calibration, showing good agreement between experimental observations and numerical predictions across intermediate stress states; and (4) development and application of a two-stage experimental methodology for evaluating fracture under non-proportional loading histories, providing a systematic assessment of path-dependent damage accumulation. Experimental results demonstrated that non-proportional loading generally leads to reduced fracture strains compared to monotonic proportional loading, with pronounced deviations governed by strain-path sequence and material anisotropy. Evaluation of the Generalized Incremental Stress State–Dependent Damage Model (GISSMO) showed that a damage exponent of 𝑛 = 2 provided the most consistent agreement with experimentally measured fracture strains across the investigated non-proportional loading conditions. Based on experimental repeatability and strain-field reliability, a hierarchy of confidence in the non-proportional fracture data was established, with v-bending tests exhibiting the highest confidence, followed by mini-biaxial, hole expansion, and shear tests. Collectively, these findings advance the understanding of path-dependent fracture and damage accumulation in DP1180 steel and provide experimentally validated guidance for improving the fidelity of forming and crashworthiness simulations involving advanced high-strength steels.
  • Thumbnail Image
    Item type: Item ,
    Tailoring Native and Transition Metal Catalytic Sites in Graphitic Carbon Nitride for Sustainable Material Design
    (University of Waterloo, 2026-02-17) Pennings, Joel
    Graphitic carbon nitride (g-C3N4) has emerged as a promising material for sustainable energy conversion applications due to its unique electronic structure, earth-abundant composition, and facile synthesis. However, its practical implementation is hindered by limitations in charge separation and catalytic activity. This thesis presents a comprehensive investigation into tailoring g-CN through advanced synthesis, exfoliation, and metal doping strategies, with a focus on enhancing its performance in air-metal batteries and photoelectrochemical systems. A novel femtosecond laser irradiation technique for g-C3N4 exfoliation is introduced, demonstrating superior control over layer thickness and defect density compared to conventional methods. The exfoliation process is optimized to yield exfoliated g-C3N4 nanosheets with tunable bandgaps and increased active surface area. Subsequently, a systematic study of metal doping (Cu, Fe, Ni, Co) on exfoliated g-C3N4 is conducted. The influence of dopant type, concentration, and incorporation method on the material's electronic structure and catalytic properties is elucidated through experimental characterization. Particular emphasis is placed on correlating the metal-nitrogen coordination environments with observed enhancements in charge transfer and oxygen reduction/evolution kinetics. The tailored M-g-C3N4 materials are then evaluated in air-metal battery and photoelectrochemical cell configurations. Viable improvements in battery capacity, cycle life, and conversion efficiency are demonstrated relative to undoped g-C3N4 and benchmark catalysts. Mechanistic insights into the enhanced performance are provided through in-situ spectroscopic studies and post-operation material characterization. Finally, the environmental impact and scalability of the developed materials and processes are assessed, providing a holistic perspective on their potential for real-world implementation in green catalysis and energy storage applications. This work establishes design principles for optimizing g-C3N4-based materials and demonstrates their promise as sustainable alternatives to precious metal catalysts in next-generation energy conversion devices.
  • Thumbnail Image
    Item type: Item ,
    Life Cycle Assessment of Milk Packaging in Canada: Evaluating Reusable Packaging under Prospective Energy Grid Scenarios
    (University of Waterloo, 2026-02-17) Cha, Alexander
    Plastic pollution remains a persistent environmental challenge in Canada, prompting growing policy attention toward single-use plastics. Yet, the life cycle implications of shifting materials or adopting reuse systems for food products, specifically milk packaging, are not well understood. This thesis conducts an ISO 14040/14044 aligned attributional life cycle assessment (LCA) comparing the environmental impacts of refrigerated milk packaging in Canada, including high-density polyethylene (HDPE) jugs, polyethylene terephthalate (PET) bottles, plastic milk pouches, liquid packaging board cartons, and glass bottles in both single-use and reusable systems. The functional unit is 12-L of pasteurized, refrigerated dairy milk contained in milk packaging. System boundaries are from cradle-to-grave for single-use formats and cradle-to-cradle for reuse scenarios, modeled in openLCA using the ecoinvent database and ImpactWorld+ impact methodology. Baseline packaging impacts are examined under current grid and recycling rates, and a scenario analysis is conducted under a prospective 2050 net-zero grid in Canada. Results show the packaging production stage dominates overall life cycle impacts, with lightweight flexible plastic milk bags performing best across most impact categories. Single-use glass exhibits the highest environmental impacts, while reusable glass shows improvement with increased reuse, though sanitization and transportation remain critical contributing stages as reuse increases. Under a decarbonized grid, reusable systems glass systems outperform select single-use packaging types but rarely surpass reusable plastic systems. Grid decarbonization improves electricity-intensive processes and strengthens relative performance of glass reuse, but does not outperform the advantages of lightweight, plastic-based systems. However, results are limited by data quality, availability, and quantification of microplastic impacts. Findings indicate that achieving circular packaging outcomes depends less on material substitution and more on system design. This study contributes novel, Canada-specific insight in how grid decarbonization and reuse interact in determining sustainable packaging strategy.
  • Thumbnail Image
    Item type: Item ,
    Analysis and Design of Lens Antennas for Power-Constrained Applications
    (University of Waterloo, 2026-02-13) Esfarayeni, Nita
    The ever-increasing demand for faster data rates as well as overcrowding in the sub-6 GHz spectrum has driven the shift to using higher frequency bands. While the use of higher frequencies can facilitate bandwidth requirements needed to meet the required data rates, they struggle with high Free-Space Path Loss (FSPL) which require specialized solutions to overcome. Phased Array Antennas (PAAs) have attracted immense attention in recent years. PAAs are able to make use of a large quantity of antennas to produce a gain high enough to overcome FSPL while also benefiting from compactness and the ability to rapidly steer and shape the beam. While they have been shown to be effective solutions for many applications, most PAAs depend on a large number of active amplifiers, which entails higher upfront costs, high power consumption, and high thermal dissipation. Such challenges must be addressed for power-constrained or heat-sensitive applications. This thesis presents a detailed analysis of existing solutions in literature and examines their trade-offs. The Lens Antenna Subarray (LAS) architecture is proposed as a solution, which offers low power consumption while keeping the Gain Over Noise Temperature (G/T) figure of merit for performance competitive with active arrays by leveraging both the directive properties of dielectric lenses as well as the flexibility of traditional PAAs. This thesis focuses on the design of a single lens and its feed network, referred to as a subarray. To produce a practical example, a Satellite Communication (SATCOM) receiver is chosen as the target application, and a subarray is designed. An ultra-wideband lens with a novel permittivity profile is designed which can provide up to ±64° of -3 dB steering, an improvement over similar Printed Circuit Board (PCB) compatible designs which typically do not provide more than ±50° of steering. Additionally, feed antennas are designed to provide wideband operation over the SATCOM receiving frequency range of 17.7 to 21.2 GHz. A total of 19 antennas are arranged in a novel feeding arrangement which enables the use of circular polarization with the lens, which has not yet been shown in literature. As the concept of LASs are relatively new to literature, there are many potential directions in which the concept can be developed. Further improvements to the lens, the simplification of feeding antennas, and array-level design are all areas which can be investigated in detail.