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 ,
    Advancing the Conditional Source-Term Estimation (CSE) Framework for Turbulent Combustion Modeling and Application to Alternative Aviation Fuels
    (University of Waterloo, 2026-04-16) Mahdipour Dilmaghani, Amir Hossein
    The aviation sector faces increasing pressure to reduce greenhouse gas emissions and pollutant formation while meeting projected growth in global air traffic. Alternative aviation fuels (AAFs), including oxygenated fuels and hydrogen, represent promising pathways toward cleaner combustion, provided that their complex chemistry--turbulence interaction can be accurately predicted. Numerical simulation plays a critical role in this effort, but its reliability depends on the availability of combustion models that are both computationally efficient and sufficiently accurate for complex fuels and turbulent flow regimes. This thesis focuses on the development, assessment, and extension of the Conditional Source-term Estimation (CSE) model for the simulation of turbulent non-premixed flames, with particular emphasis on alternative aviation fuels. First, several CSE formulations are systematically evaluated, including traditional Tikhonov-regularized inversion and a Bernstein-polynomial-based approach, with the aim of improving numerical stability, accuracy, and computational efficiency. Next, a new CSE framework incorporating direct integration of detailed chemical kinetics is introduced, eliminating the reliance on pre-tabulated chemistry and enabling more robust predictions for fuels and conditions that are not well represented by conventional chemistry manifolds. The proposed developments are validated against well-documented laboratory-scale turbulent jet flames, including methane, dimethyl ether (DME), and hydrogen flames, covering different fuels and flow scenarios. The effects of differential diffusion are incorporated into the CSE-direct chemistry framework for hydrogen flames, addressing a key limitation of previous CSE implementations. An adaptive and automated CSE ensemble definition strategy is also presented and tested in large eddy simulation (LES) to capture local extinction dynamics. Overall, this work advances the CSE methodology by enhancing its flexibility, physical fidelity, and applicability to alternative aviation fuels. The results demonstrate that CSE with direct chemistry integration can achieve accurate turbulence–chemistry interaction predictions while maintaining computational efficiency, thereby providing a viable modeling framework for future simulations of advanced combustion systems relevant to sustainable aviation.
  • Thumbnail Image
    Item type: Item ,
    Practical Distributed Key Generation and Signatures
    (University of Waterloo, 2026-04-16) Komlo, Chelsea
    Threshold schemes are a critical cryptographic primitive that allows a set of n total parties and a threshold of at least tparties to collaborate to jointly perform some function, such as generating key material or issuing a digital signature. Threshold schemes allow for improved robustness in the case of failure, and distribute trust among many parties. In particular, the security of the scheme assumes t−1 players are corrupted, and so can deviate arbitrarily from the protocol. The security of the scheme ensures that in spite of a subset of corrupted players, the scheme can provide important properties such as robustness, unforgeability, or indistiguishability from some target distribution. In this work, we examine the special cases of distributed key generation and threshold signing. In particular, we present constructions that optimize for considerations that are important to implementations in practice. Such considerations include simplicity, network round efficiency, computational and bandwidth efficiency, and low use of broadcast channels. Firstly, we present FROST, a Flexible Round-Optimized Schnorr Threshold signature scheme. FROST improves upon prior threshold Schnorr signature schemes in that signatures can be generated with only two network rounds among participants, while remaining secure against concurrent adversaries. We show that FROST is secure under the Algebraic One-More Discrete Logarithm (ℓ-AOMDL) assumption in the Random Oracle Model (ROM). Secondly, we present Storm, a simplified three-round distributed key generation protocol (DKG). Storm presents a simplified alternative to prior DKGs with a similar security model, assuming the Discrete Logarithm Problem (DLP) is hard, and provides a generic construction that may be applicable beyond discrete-logarithm assumptions. Finally, we present Arctic, a two-round deterministic threshold Schnorr signature scheme. Arctic allows signers to remain stateless, with the exception of persisting state of their long-lived signing keys. Arctic requires a slightly weaker trust model in that it assumes the majority of signers are honest, but shows improved efficiency over alternative deterministic threshold Schnorr signature schemes for small signing coalitions (fewer than 25 signers). We show that Arctic is secure assuming DLP in the ROM.
  • Thumbnail Image
    Item type: Item ,
    Development of Cross-Conjugated Polymers for Sensing Applications
    (University of Waterloo, 2026-04-16) Zhao, Naixin
    Conjugated polymers are an important class of materials for electronic applications. Compared to conventional inorganic semiconductors, they offer mechanical flexibility, solution processability, and tunable electronic properties. Recently, the research interest in polymer-based sensing technology has grown considerably due to the increasing demand from emerging fields such as the Internet of Things (IoT), smart packaging, and healthcare electronics. Sensors based on conjugated polymers have demonstrated promising performance towards various stimuli such as liquid chemicals, gaseous compounds, and temperature. However, they still suffer from several limitations, including insufficient stability, reversibility, and manufacturing challenges. This thesis aims to address these issues through the exploration of novel material designs based on cross-conjugated building blocks, which have received less research interest compared to linear conjugated structures due to their inherent lower carrier mobility. For sensing applications, their unique ability to transform into a linear conjugated structure under specific stimuli could be beneficial for enhanced sensor sensitivity and selectivity. Additional design strategies are employed for enhanced sensing performance, including the incorporation of hydrogen-bonding sites for reversible sensing and the development of intrinsically conductive polymers to eliminate the need for external dopants, potentially improving device stability. In the first part of the study, dihydropiperazine (DHP) is chosen as the target cross-conjugated building block. A novel building block bisindolin-dihydropiperazine (IDHP) is developed and further copolymerized with a thienothiophene (TT) unit to constitute the cross-conjugated polymer, PIDHPTT. IDHP monomer exists as a cross-conjugated lactam but converts to a conjugated lactim form within the polymer. Neighboring DHP units in the lactim form facilitate this process through π-bridges, demonstrating a vinylogous effect, which has previously only been observed in small molecules. The OH groups in the lactim DHP interact more strongly with fluoride ions (F-) than other halides (Cl-, Br-). A water-gated organic field effect transistor (WGOFET) sensor based on PIDHPTT shows excellent sensitivity (LOD = 0.28 μM) and selectivity for fluoride ions over other halide ions, in addition to excellent reversibility and high stability in ambient and aqueous environments, demonstrating the potential of this polymer design for aqueous chemical sensing applications. Next, two thiophene-flanked DHP-based polymers, PTDbT-ET and PTDbT-T, are developed and synthesized with the eco-friendly DArP method. Incorporation of tri-ethylene glycol (TEG) side chain significantly raises their HOMO energy level higher than the ambient oxygen oxidative potential, enabling spontaneous doping by oxygen gas in the presence of moisture. Due to the higher abundance of TEG groups in PTDbT-T, it possesses a larger energy trap between its HOMO and oxygen oxidative potential, forming a more stable charge transfer complex (CTC) and can maintain its conductivity by storing in a moisture-free environment. When tested toward volatile organic compound (VOC) gaseous analytes, PTDbT-T-based chemiresistive sensors demonstrate excellent repeatability and stability, in addition to high sensitivity and selectivity to ethanol (LOD = 3.07 ppm) over other alcohol species, demonstrating the potential of this alternative strategy to develop dopant-free conductive polymers for chemiresistive gas sensor applications. In the second part of the study, a novel cross-conjugated polymer and the first polymeric analogue of a quinhydrone-like charge-transfer complex with intrinsic conductivity, poly(3,4-dihydroxythiophene-alt-thiophene-3,4-dione) (P(HOT-DOT)), is designed and synthesized. The ammonia-coordinated polymer P3 generates a perfectly balanced 1:1 donor-acceptor architecture that promotes self-doping and stabilizes polarons with spontaneous air oxidation. The polymer exhibits a narrow bandgap, broad near-infrared absorption, and high intrinsic conductivity (∼0.29 S cm-1), enabled by an ultrasmall π-π stacking distance (3.25 Å) despite its cross-conjugated backbone. Flexible temperature sensors fabricated from P3 show high stability, rare positive temperature coefficient (PTC) behavior, and reproducible and linear thermal responses over multiple cycles (TCR = 0.113 ± 0.00045%/°C). Ongoing and future studies of this material should focus on expanding other basic coordination groups for higher material stability and targeting unique electronic properties for high-performance organic electronics applications.
  • Thumbnail Image
    Item type: Item ,
    Roadway Illumination Level Assessment for Driver Safety and Comfort: A Multimodal Human Factors Evaluation of Visual Behavior, Physiological Arousal, and Driving Performance in a High-Fidelity Driving Simulator
    (University of Waterloo, 2026-04-16) Abdalla, Shene
    Nighttime driving remains a major road safety concern because reduced illumination can impair visibility, delay hazard detection, and increase visual strain. Although roadway lighting is intended to improve safety, greater brightness does not always produce better driving conditions. Excessive illumination may introduce glare, discomfort, and unnecessary energy use without meaningfully improving driver response. This thesis investigates how different nighttime illuminance levels influence driver safety and comfort by examining their relationship with multimodal safety-related measures, with the aim of identifying the illumination level that best supports visual detection, driving performance, physiological stability, and perceived visibility, comfort, and safety. A controlled mixed-design experiment was led in a high-fidelity virtual driving simulator using a replicated real-world street environment under three nighttime illuminance levels, low, medium, and high, established in accordance with roadway lighting standards. Thirty licensed drivers participated in the study, equally divided between younger adults aged 20 to 45 years and older adults aged 65 years and above. Driver response was evaluated using a multimodal framework integrating eye-tracking (Time to First Fixation (TTFF), Dwell Time), simulator-based driving measures (PRT, Speed, Hazard-related Deceleration), physiological markers (Heart Rate (HR), Electrodermal Activity (EDA)), subjective ratings of perceived visibility, comfort, and safety, and qualitative feedback. The results showed a clear relationship between illuminance level and driver response. Low illuminance was associated with delayed visual detection, slower hazard response, higher physiological arousal, and poorer ratings of visibility, comfort, and safety. Increasing illuminance from low to medium improved TTFF and PRT, enhanced perceived visibility and comfort, and supported greater physiological stability, whereas increasing illuminance from medium to high produced little additional benefit and occasionally introduced glare-related discomfort. Older adults showed higher physiological arousal and more conservative braking behavior than younger adults, but both age groups followed the same overall pattern across illuminance levels. Overall, the findings show that effective nighttime roadway lighting is not achieved by maximizing brightness, but by selecting an illumination level that supports visual effectiveness, driver response, comfort, and physiological stability. Among the conditions examined, medium illuminance provided the most favorable overall balance for safer and more efficient driving. These findings provide practical guidance for roadway lighting design and planning by suggesting that moderate illumination may offer the most effective balance between safety, comfort, and physiological stability.
  • Thumbnail Image
    Item type: Item ,
    Personality, Individuality, and the Social Lives of Bats
    (University of Waterloo, 2026-04-16) Ryan, Caleb
    Individual animals are unique and often differ substantially in their behaviour. Explaining how and why behavioural variation persists among individuals is central to behavioural ecology and requires methods that can capture both stability and uncertainty in complex data. In this thesis, I use a modelling approach to estimate the repeatability of behaviours observed from subjective assessments, standardized personality assays, and long-term monitoring of social interactions in the wild. Using bats as a study system, I investigate the extent of individual behavioural variation, how consistent differences contribute to sociality, and how individuality persists over evolutionary time. In Chapter 2, “Conserving cryptic complexity: Bats with broker roles structure the maternity societies of an endangered bat species”, I examine how individuals with distinct social roles contribute to the cohesion of Little Brown Bat (Myotis lucifugus) maternity colonies. I use a permutation-based network analysis to determine the positions of individuals in the social network across multiple years. My results reveal that a small subset of individuals can consistently act as brokers, meaning they bridge otherwise disconnected roost-area subgroups and maintain population-level social cohesion. Given that the same phenomenon is observed in two separate maternity societies of different sizes, this result suggests that these individualized social roles may be a feature of little brown bat sociality. Further, these results simulate how the loss of a small number of individuals from bat populations post-white-nose syndrome could have devastating impacts on social cohesion. This highlights the need to protect surviving individuals that persist on the landscape following population collapse. In Chapter 3, “Experimentally quantified personality traits are consistent across multiple years yet cannot explain observed differences in the social behaviour of bats on the landscape”, I test whether consistent individual differences in social behaviour among Little Brown Bats are linked to personality. Here I combine Bayesian social relations models of network structure with Bayesian hierarchical models of personality test scores to statistically propagate uncertainty from both social network estimates and behavioural assays into a joint analysis. I find strong evidence that behavioural tendencies are repeatable within individuals across multiple years. This finding is consistent with the concept of personality. However, assayed personality traits do not predict individual differences in social network positions, despite the repeatability of both. These findings suggest that personality and social network position, though both individually consistent, may be shaped by different processes. In Chapter 4, “Statistically upset: Fear response as a species-typical behaviour among neotropical bats”, I extend my behavioural comparison to apply a subjective personality assay to quantify fear-response behaviour in >3400 individuals from 55 Neotropical bat species across four countries. Using Bayesian hierarchical and phylogenetic mixed models, I investigate the sources of among-individual behavioural variation across species at multiple levels. I find that fear-response exhibits weak phylogenetic signal, with closely related species often differing markedly. I also find that species-typical fear-responses remain consistently distinct across geographic regions, suggesting that fear-response is a result of species-level differences and not shared environmental factors. None of the explanations for variation in fear-response investigated yielded positive results. That is, neither individual physiology nor species’ ecological and social traits explained the observed variation. Finally, I show that consistent individual differences are detectable across species, suggesting that species-level divergence in fear-response may arise through the accumulation of within-species individuality.