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    Numerical Investigation of Compact Flow-Field Designs in Proton Exchange Membrane Fuel Cell Bipolar Plates Using Integrated Flow Rectifiers
    (University of Waterloo, 2026-11-02) Amirsoleymani, Amirhossein
    Bipolar plates (BPs) are crucial components of proton exchange membrane fuel cells (PEMFCs), responsible for reactant distribution, current collection, and water/thermal management. In parallel-channel BP configurations, a header region is required to achieve uniform reactant delivery over the active area, especially at high current densities. However, the header can occupy approximately 30-40% of the BP area, increasing material cost and reducing volumetric power density. Therefore, compact headers with flow rectifiers are investigated in this dissertation to improve flow uniformity, control pressure drop and enhance electrochemical performance. At the flow-field design level, this thesis first investigates GuideVane (GV) structures as flow rectifiers in PEMFC bipolar plate headers. A three-dimensional steady-state CFD model is developed to examine how GV configurations affect Single-Phase reactant distribution in the header and parallel-channel regions. Key parameters, including GV number, gap aspect ratio, obstacle size, and GV arrangement, are evaluated in terms of flow uniformity and pressure-drop behavior. The results show that properly designed GV structures with multi-gap structure can form rectangular Pin-Type flow-rectifying elements, redistributing reactant flow more uniformly across the active area without excessive hydraulic loss. This observation motivates the next stage of the study, where compact headers with equidistant Pin-Type obstacles are investigated. The second part of this thesis extends the study to a three-dimensional computational investigation of compact header designs with integrated flow obstacles in a proton exchange membrane fuel cell bipolar plate. The analysis examined how header size, obstacle geometry, and porous-region characteristics affect reactant distribution, pressure drop, and overall cell performance. A combined performance metric was used to evaluate the trade-off between flow uniformity and hydraulic losses. The results showed that compact headers can improve the effective use of the bipolar plate area and increase apparent power density; however, they also create challenges related to flow maldistribution and pressure loss. The findings further indicated that performance is governed by the coupled interaction between header dimensions, obstacle size, and porosity, rather than by a single parameter. Therefore, compact header designs require strategically placed flow rectifiers to improve reactant distribution while preserving the benefits of reduced inactive plate area. Building on these rectifier studies, two compact header layouts with different flow rectifiers were developed: GuideVane and Pin-Type designs. Both configurations were refined through iterative design optimization to improve flow uniformity while maintaining acceptable pressure loss. The optimized designs were then evaluated using a three-dimensional multiphysics proton exchange membrane fuel cell model under Single-Phase electrochemical operating conditions. This analysis connected header geometry to cell-level performance by examining current-density distribution, species transport, and electrochemical response. Compared with the bare case (without flow rectifiers), both optimized compact headers improved reactant utilization, reduced localized transport limitations, and increased volumetric power density. Under Single-Phase conditions, the GuideVane design showed better overall performance for compact header applications. Finally, the optimized compact-header configurations are examined under Two-Phase operating conditions using coupled Volume of Fluid (VOF) and electrochemical modeling frameworks. This analysis investigates how GV- and Pin-Type rectifier geometries affect liquid-water transport, water accumulation, flooding tendency, pressure drop, and cell performance at high current density. The results show that compact-header geometry strongly influences both reactant delivery and water-removal pathways, offering advantages over larger header designs. The comparison further shows that Pin-Type rectifiers provide stronger water-removal capability by promoting pressure-driven droplet evacuation within the header and flow-field regions. By integrating compact-header design, optimized flow rectifiers, and Two-Phase performance analysis, this thesis lays the groundwork for developing PEMFC bipolar plates with improved flow distribution, enhanced water management, higher volumetric power density, and more reliable operation.
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    Development and Validation of a Miniaturized Ultrasonic Measurement System for Acoustic Characterization of Human Urine Samples
    (University of Waterloo, 2026-11-02) Cain, Liam
    Urine analysis is a common method of diagnosing conditions in a medical context. Common testing methods, such as a urinalysis dipstick test, use colour-changing pads to detect analytes within the composition of the urine. However, collecting and analyzing a sample using this method introduces contaminants and requires qualitative assessment with introduces human error which may affect the results. Ultrasound (US) wave propagation offers a potential non-invasive method of characterizing urine by measuring acoustic properties like the speed of sound (SoS) and the acoustic attenuation coefficient (AC). These properties vary depending on the physical properties of the medium, including density and composition. Although the SoS and AC of human urine exhibit potential as effective biomarkers for pathological conditions, the SoS and AC of human urine have rarely been investigated in literature. By utilizing the properties of ultrasound wave propagation to characterize the acoustic properties of urine, acoustic information can be collected from individual samples to form a well-defined dataset. A recruited population of 40 volunteer participants, over 18 years of age, provided samples which were analyzed using a custom experimental setup. Transducers transmit pulses in a pitch-catch orientation at variable distances (1 – 10 cm) to obtain both SoS and AC values at two temperatures (37 °C and 23 °C). The measured distance value, along with the time-of-flight of the signal, are used to obtain the SoS. Total signal loss obtained from the amplitude at various distances, is made up from attenuation, diffraction, and system losses. Using characterization and references to isolate and fit the attenuation gives us the AC. The density of the urine was also measured through a simple mass/volume relationship. The 40-volunteer dataset of AC and SoS values were compiled paired with defined typical and non-typical analyte readings. SoS and AC values ranged from 1490 – 1580 m/s and 0.035 – 0.45 dB/cm at 5 MHz across the two measured temperatures. The AC, SoS, and density values for both typical and non-typical samples were statistically compared and analyzed for significance to determine key identifiers within urine such as bilirubin and hemoglobin (p < 0.05). This thesis involves creating and implementing a new instrument design that is used to obtain a reference of urine acoustic properties and demonstrates feasibility of ultrasound-based urine characterization. Lessons learned through the course of the study lead to the refinement of the measurement apparatus, implementing a more accessible form factor while maintaining most functionality. The study findings provide a foundation for investigating AC and SoS as potential biomarkers for pathological conditions and to inform future studies that stem from this work.
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    People, Places, Spaces: Creating A Foundation For Women’s Safety In Hostels To Allow Social Connections To Flourish
    (University of Waterloo, 2026-11-02) Wonnacott, Hannah
    This thesis is centered around a woman who is solo-travelling, who stays in hostels and wishes to connect and share experiences with like-minded people. However, it is not always considered safe for a woman to be travelling by themselves. This thesis explores how the hostel can provide opportunity for meaningful connections with other travellers while balancing the needs of personal safety and privacy in a shared space. Through a combination of user surveys, precedent analysis, design guidelines, and architectural investigation, this thesis identifies the spatial conditions that encourage social interaction and the design strategies that establish safety and privacy among travellers. The findings of this research was translated into three design proposals that respond to typical urban lot typologies: infill, open, and corner. Each design explores a distinct architectural strategy but maintains a shared approach to safety, privacy, and social interaction. Together, these designs demonstrate there is no singular architectural model for a socially connected and safe hostel; rather, connection can emerge through different spatial responses to context. Ultimately, the thesis proposes the hostel as a temporary network of people, places, and spaces, where architecture creates the conditions for strangers to arrive, connect, and then continue on their separate journeys.
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    Prosthesis and Prejudice: Potential Bias, Procurement, and Prescribing Patterns in Canadian Knee Arthroplasty
    (University of Waterloo, 2026-11-02) Loughlin, Naomi
    Background Total knee arthroplasty (TKA) implant selection is influenced by patient, surgical, institutional, and implant-specific factors, yet national data describing these patterns in Canada remain limited. This thesis used data from the Canadian Joint Replacement Registry (CJRR) to characterize TKA implant use and examine variation in implant selection across Canada from 2019 to 2023. Methods An open-source implant reference library and validation pipeline were developed to improve the identification and classification of implant manufacturers and models. These tools were used to characterize national and provincial trends in fixation method, patellar resurfacing, implant stability, and manufacturer and model utilization. Finally, clustering methods were applied to identify latent implant prescribing configurations and assess whether patient characteristics explained cluster membership. Results The implant reference library substantially improved the usability and granularity of CJRR data and demonstrated potential for retrospective data validation. Cementless fixation increased substantially over the study period and was more common among male and younger patients. Patellar resurfacing and posterior-stabilized design utilization declined as medial-pivot designs increased, while cruciate-retaining designs remained relatively stable. Substantial provincial variation was observed across fixation, resurfacing, stability, and manufacturer- and model-level implant selection. Manufacturer trends indicated that some observed practice changes were likely influenced by market composition. Of note, the Stryker Triathlon system accounted for much of the shift toward cementless fixation. Clustering identified six distinct TKA prescribing configurations, primarily differentiated by fixation, stability, and implant model. Similar configurations emerged when model identity was excluded as a clustering input, demonstrating convergence on broad functional design categories across manufacturers. Patient characteristics did not substantially explain cluster membership. Conclusions TKA implant selection in Canada converged on broad functional design configurations alongside some model-specific trends (e.g., Stryker Triathlon cementless), with substantial variation across patient groups and provinces. The findings of this thesis suggest that market composition, procurement practices, and unmeasured institutional and surgical factors may contribute to the observed prescribing patterns. Strengthening registry data usability through standardized implant identification and incorporating additional surgical and institutional variables could enable more granular analyses of implant selection. Future research should link these prescribing patterns to clinical outcomes to determine whether observed variation influences patient care and identify opportunities to improve the quality and value of TKA in Canada.
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    Analysis and Evaluation of Non-Blocking Interpolation Search Trees
    (ACM, 2020-01-02) Prokopec, Aleksandar; Brown, Trevor; Alistarh, Dan
    We start by summarizing the recently proposed implementation of the first non-blocking concurrent interpolation search tree (C-IST) data structure. We then analyze the individual operations of the C-IST, and show that they are correct and linearizable. We furthermore show that lookup (and several other non-destructive operations) are wait-free, and that the insert and delete operations are lock-free. We continue by showing that the C-IST has the following properties. For arbitrary key distributions, this data structure ensures worst-case O(log n+p) amortized time for search, insertion and deletion traversals. When the input key distributions are smooth, lookups run in expected O(log log n+p) time, and insertion and deletion run in expected amortized O(log log n+p) time, where p is a bound on the number of threads. Finally, we present an extended experimental evaluation of the non-blocking IST performance.