Theses

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The theses in UWSpace are publicly accessible unless restricted due to publication or patent pending.

This collection includes a subset of theses submitted by graduates of the University of Waterloo as a partial requirement of a degree program at the Master's or PhD level. It includes all electronically submitted theses. (Electronic submission was optional from 1996 through 2006. Electronic submission became the default submission format in October 2006.)

This collection also includes a subset of UW theses that were scanned through the Theses Canada program. (The subset includes UW PhD theses from 1998 - 2002.)

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Development of Hybrid Non-Enveloped Viral Vectors Using the Bacterial Miniphagemid Platform
(University of Waterloo, 2026-01-30) Hosseinali, Mehraveh
Gene therapy holds significant promise for treating various diseases, with Adeno-associated virus (AAV) vectors being among the most widely used delivery systems. However, current standard AAV production methods relying on costly and inefficient mammalian cell culture limit scalability and clinical accessibility. A similar human virus, Torque teno virus (TTV), also holds great potential for gene therapy; however, it also suffers from problems in its production. To address this manufacturing bottleneck, this study aimed to develop a novel, cost-effective platform for hybrid viral vector production entirely within Escherichia coli. This work advances research on the use of miniphagemids, phages that package a minimal vector genome, to achieve in-bacterial assembly of novel hybrid AAV serotype 2 (AAV2)-based and TTV genotype 19 (TTV19)-based vectors. The hypothesis being tested is that the co-production of single stranded DNA using miniphagemid technology and key AAV or TTV proteins in Escherichia coli can result in AAV-based or TTV-based vectors. The key objectives were therefore: 1) showing recombinant expression of heterologous capsid proteins AAV2 VP1/VP2/VP3 and TTV19 ORF1 in E. coli; 2) producing ssDNA minigenomes flanked by either AAV2 inverted terminal repeat (ITR) or TTV19 untranslated terminal repeat (UTR) sequences; and 3) showing that co-producing protein(s) and ssDNA results in AAV2- or TTV19-based vectors. Results confirmed that AAV2 VP2 and VP3 could be produced in E. coli, albeit expressed primarily as insoluble inclusion bodies. Transformation of cells with a plasmid encoding VP1 resulted in reduced growth and no VP1 was recovered. Expression of TTV19 ORF1 in E. coli produced two histidine-tagged protein products approximately half the size of the expected protein (as previously reported). The ssDNA minigenomes were successfully produced and purified, exhibiting high purity (Objective 2). The central finding was the successful in-bacterial production and purification of functional hybrid vectors, termed AAV-based and TTV-based (Objective 3). Iodixanol gradient ultracentrifugation confirmed particle assembly and density separation. Subsequent qPCR quantification demonstrated high genomic titers in the purified fractions, providing strong evidence of successful ssDNA encapsulation by the heterologous capsids within the E. coli host. The study further found that the TTV19 UTRs likely enhance packaging efficiency in the TTV-based hybrid vector system. In conclusion, this research establishes a robust and scalable E. coli-based platform for producing non-enveloped hybrid viral vectors. This achievement represents a significant step toward revolutionizing gene therapy vector manufacturing, offering a pathway to highly purified, consistent, and affordable therapeutic vectors.
Household, Neighbourhood, and Community Contexts and the Mental Health of Immigrants and Immigrant Mothers: An Ecological Perspective
(University of Waterloo, 2026-01-30) Khan, Tasneem
Abstract There is growing recognition in the public health field that the determinants of mental health extend beyond biological aspects to include one’s living environment and social context. Research from an ecological perspective has emphasized the importance of contextual factors across multiple levels, such as households and neighbourhoods, in determining mental health. In addition, social positions such as immigrant status, being a woman, and motherhood shape exposure to different contexts and influence mental health outcomes. This dissertation investigates how household, neighbourhood, and community-level factors influence the mental health of immigrants as well as immigrant, racialized and ethnic minority mothers in Canada. In the empirical chapters of this dissertation, Statistics Canada’s survey data were analysed to examine the associations between contextual factors at multiple levels and mental health. First, the Canadian Community Health Survey 2015/16 and the Canadian Index of Multiple Deprivation (CIMD) were used to investigate the association between factors in the household, neighbourhood, and community contexts and the mental health of immigrants in Canada. Second, the General Social Survey 2016, 2017, and 2018 were used to explore how family structure, dwelling characteristics, and household contextual factors relate to the mental health of immigrant and Canadian-born mothers. The final study is a scoping review of the literature from Canada and the United States, focusing on identifying risk and protective factors within the neighbourhood and community contexts affecting the mental health of immigrant and racialized and ethnic minority mothers. Evidence emerged for some factors that can be considered risks and others that are protective of mental health across contextual levels. At the household level, socioeconomic disadvantage in the form of low income adequacy and low household income was related to poor mental health among immigrants and Canadian-born mothers. Being a single versus a partnered mother was also associated with poor mental health outcomes. Factors related to children, such as the age and number of children at home, were not associated with mental health outcomes. At the neighbourhood and community level, negative factors included a weak sense of belonging to the local community and living in an area with higher ethnocultural concentration, reflecting marginalization as measured in the CIMD. Negative factors also included a high proportion of dwellings in need of repair and lower education levels, captured using the situational vulnerability dimension in the CIMD. Findings from the scoping review suggested that deteriorated physical conditions and violence within neighbourhoods negatively impact mental health. On the other hand, a larger household size was associated with lower odds of having a mental health condition and was protective for both immigrant and Canadian-born mothers. While the empirical studies did not directly assess the role of social support and community programming, findings from the scoping review suggest that mental health outcomes are shaped by these factors. Community-based programs related to social and mental health services may help mitigate the effects of socioeconomic disadvantage and foster social inclusion. Social support from friends and family was also found to mitigate the relationship between poor neighbourhood environments and depression among racialized mothers. The findings from all three studies could be used to inform strategies for mental health equity at the community and neighbourhood levels in Canada. This includes interventions at the community level with tailored supports for diverse and larger families to promote the mental well-being of immigrant and racialized populations. In addition, affordable childcare and housing supports for single and low-income mothers could also be beneficial for protecting mental health.
Examining Enabling Conditions of Multi-loop Social Learning in Integrated Flood Risk Management: Evidence from Ontario’s Conservation Authorities in a Flood Management Network Context
(University of Waterloo, 2026-01-30) Ciardulli, Paolo
Flood risk remains a persistent societal challenge, as no existing measures can offer complete protection against its impacts. Despite advancements in forecasting technologies, infrastructure and policy, flood events continue to result in substantial economic, social and environmental consequences. The complexity of managing flood risk stems from the interaction of dynamic and interrelated factors such as land-use change, risk constructs, governance structures, stakeholder priorities and coordination mechanisms. Integrated Flood Risk Management (IFRM) offers a comprehensive approach, recognizing the need for coordination across governmental levels, sectors and stakeholders while adapting to changing conditions. Within these interconnected socio-ecological systems, continuous learning and adaptation are essential. Social learning, particularly Multi-Loop Social Learning (MLSL), is a key supportive element of IFRM, yet it remains underexplored in this context. This dissertation investigates the presence of theoretically grounded MLSL capacities and enabling conditions in the practices and collaborative processes of Ontario’s Conservation Authorities (CAs). Particular attention is given to their interactions with the broader Ontario flood management network. These MLSL factors are theorized to play a critical role in supporting the development and application of an IFRM strategy. The IFRM strategy used in this research is modeled after a multi-phased, bio-regionally based, iterative, real-world and documented example: the European Union’s Floods Directive. The study examines how MLSL capacities align with the demands of such an IFRM approach in the Ontario context. Therefore, it situates Ontario within a broader Canadian conversation about the intersection of river basin-based water resources management and MLSL. Ontario’s CAs, which are river basin–based organizations with legal mandates in flood risk reduction, served as embed units of analysis within the wider case study (i.e., the CA flood management network) for this research. A two-round Delphi survey was conducted with 20 flood risk management (FRM) experts. Survey questions were designed to reflect MLSL factors derived from a previously developed research framework which focused on said factors in the context of Québec’s watershed management organizations. The modified Delphi approach also made it possible to capture both consensus and divergence between academic and practitioner perspectives. Findings indicate that several enabling MLSL capacities are evident in Ontario’s IFRM setting. These include (1) collaborative partnerships and networks, (2) an intentional approach to learning regarding collaborative processes, (3) sustained participation with governmental stakeholders, (4) cross-sectoral collaboration, (5) internal technical expertise, and (6) learning related to project goals. Respondents attributed these capacities to the CAs’ pivotal roles in flood management networks, long-standing engagement with municipalities and the province, their ecosystem-based approach, and their ability to convene diverse stakeholders across watersheds. CAs were also recognized for their multidisciplinary teams, adaptive management practices, and facilitation skills. Conversely, the study identified several areas where MLSL capacities are lacking. These include (1) shared data access among governmental actors, (2) collaborative decision-making across governmental levels, (3) an enabling democratic environment, (4) in-depth project reflection using formalized assessments, and (5) access to external expertise. Respondents attributed these gaps to uncertainty about data access, staff and funding constraints, inconsistent capacity among CAs, governance limitations, and unclear roles of external experts. These gaps highlight both institutional and policy limitations that impact the potential to fully transition toward IFRM in Ontario. This research isolates and analyzes specific MLSL themes, thus, making it possible to assess specific conditions that enable capacity for MLSL. Two key dimensions emerged: (1) the extent to which MLSL capacities are present and (2) how they manifest across IFRM phases. Together, these insights reveal the degree to which MLSL supports IFRM strategy development and implementation. A cross-comparison with a seminal study found convergence on 9 of 11 MLSL themes. This degree of alignment suggests that MLSL capacity challenges are broadly consistent across Canadian river basin-based water resources management contexts; particularly between Ontario and Québec. This study contributes to scholarly discourse by advancing understanding of MLSL in IFRM settings and offering practical insights for flood management organizations seeking to transition toward more integrated and adaptive approaches. The broader problem this research addressed is the extent to which watershed management agencies, or similar institutions, can effectively transition from one management model to another, particularly when such a transition necessitates the development of specialized MLSL capacities required for implementing the new strategy or model. In parallel, the research highlights policy needs by showing where Ontario’s flood strategy can be reinforced: shared data systems, inclusive decision-making, reflexive evaluation, expanded expertise and sustained multi-sectoral collaboration.
Laurentide Ice Sheet dynamics across multiple glacial-interglacial cycles from Quaternary stratigraphic records in the western Hudson Bay Lowland, central Canada
(University of Waterloo, 2026-01-29) Hodder, Tyler
Understanding the terrestrial Quaternary stratigraphic record is necessary to reconstruct regional- to continental-scale paleo-ice sheet fluctuations and compare how these events relate to oxygen isotope proxies derived from marine sediments, sea level change, and contemporary ice sheets. Regions that contain an extensive stratigraphic record beyond the last glacial maximum are key to understanding the long-term behaviour of ice sheets and provide field-based constraints for ice-sheet reconstructions and modelling. The Hudson Bay Lowland (HBL) is one of these key regions situated in central Canada that contains a fragmented stratigraphic record of at least the last four Laurentide Ice Sheet (LIS) glaciations. The main objectives of this thesis are to 1) reconstruct the spatio-temporal evolution of the LIS from the Quaternary stratigraphic record of three relatively understudied regions of the western HBL and 2) determine the timing and climate conditions that persisted during ice-free periods across multiple glacial-interglacial cycles. To better understand the fragmented stratigraphic record that is dominated by glacial sediments (till), this thesis developed a hybrid lithostratigraphy-allostratigraphy approach that relies on multi-parameter characterization of tills to establish sediment provenance and the ice-flow direction that deposited the sediment. This included detailed study of 70 sections, the collection of 193 stratigraphic ice-flow indicators (154 till fabrics and 39 lodged clasts) and analysis of 393 till samples. Once the till framework was established, the relative age of each nonglacial bed was then determined using the bounding surfaces of designated till units. At least 18 units have been identified this way and correlated across the western HBL. The nonglacial beds were further characterized to assess the timing of sediment deposition using radiocarbon and optical dating methods and paleo-environmental conditions that existed using pollen and foraminifera analysis. Lastly, stratigraphic frameworks presented herein did not rely on geochronology constraints to anchor correlations and the age of identified interglacial beds can be further tested to confirm the age of interglacial beds. The new stratigraphic framework for the western HBL provides important field-based constraints for LIS reconstructions. This includes evidence that there was asynchronous growth of the two major domes of the LIS during the last two glaciations, with accelerated early growth of the Quebec–Labrador Dome relative to the Keewatin Dome. In each glaciation, the Keewatin Dome becomes more active relatively later in glaciation and persists until deglaciation. During the last glaciation, ice-flowing from the Keewatin Dome likely did not occur until MIS 2 and this S-trending ice-flow transitions into late-glacial SW-trending ice-streams. During the penultimate glaciation (~MIS 6), till deposition by S- to SW-trending ice was extensive and one of the main ice-flow events across the western HBL when the Keewatin Dome was likely situated in northern mainland Nunavut. Furthermore, during deglaciation the Keewatin Dome or an ice divide was likely situated in the western HBL. There is widespread evidence across the western HBL that sediments belonging to at least three pre-Holocene interglacial periods exists, which provides an important archive to understanding past climatic conditions in central Canada. For two of these interglacials there is evidence of marine inundation which likely occurred during Termination II (~130 ka) and Termination III (~243 ka). In the Churchill River region, the marine limits for both marine incursions are higher compared to the Tyrrell Sea (Holocene) marine limit, providing important field-based constraints for LIS modelling. Importantly, new age estimations from the uppermost intertill nonglacial sediments, combined with consideration of the paleobotanical datasets in the western HBL stratigraphic record, suggest that the region was last deglaciated during MIS 5e. This implies that the HBL, and likely Hudson Bay, remained glaciated during MIS 3. The presence of weathered bedrock within the western HBL indicates that glacial erosion of bedrock was negligible in places during the Quaternary Period. Relict landscapes across northeastern Manitoba, such as preserved streamlined landform flowsets that are situated outside the margins of late-glacial ice streams, provide evidence of limited erosion following initial glacial advance into the area. The results of this thesis have provided an updated Quaternary stratigraphic framework for the western HBL, a key region for understanding the long-term evolution of the LIS. The Quaternary stratigraphic record is highly fragmented, which reflects patchy erosion and deposition over multiple glacial-interglacial cycles of the region. The new stratigraphic frameworks developed provide an increased understanding of the growth, evolution and retreat of the LIS during the past two glaciations and insights into pre-Illinoian glaciations, which are essential to improving reconstruction and modelling of the ice sheet throughout the Middle and Late Pleistocene.
Correlation-Aware Rendering: Improving Sampling and Denoising for Realistic Image Synthesis
(University of Waterloo, 2026-01-29) Zhou, Weijie
In realistic image synthesis, Monte Carlo integration is the foundation of most rendering algorithms, but it inevitably introduces noise. To reduce such noise, advanced sampling strategies—such as Markov chain Monte Carlo (MCMC), resampled importance sampling (RIS), and modern denoising techniques—have been proposed. However, these methods of ten introduce correlations that can manifest as new artifacts. This thesis investigates three distinct research directions, spanning from mitigating correlation to actively exploiting it. The first direction tackles correlation in MCMC methods. Traditional MCMC often suffers from low acceptance rates, producing visually “spiky” noise. We propose combining MCMCwithpathguiding techniques to improve acceptance probabilities, thereby reducing correlation artifact and improving image quality. The second direction addresses correlation artifacts in the widely used Reservoir-based Spatiotemporal Importance Resampling (ReSTIR) algorithm. While ReSTIR achieves ef f icient sampling by reusing samples across pixels and frames, this reuse can lead to blotchy artifacts, as many pixels may end up sharing only a few important samples. Observing par allels between ReSTIR and MCMC, we introduce a new spatiotemporal MCMC framework that replaces reservoir resampling. Applied to both direct illumination and path tracing, our approach significantly reduces correlation artifacts while retaining efficiency. The final direction shifts from reducing correlation to exploiting it. We present a gener alized combination framework that leverages spatial, temporal, and multiscale correlations to reduce error. This method enables robust cross-domain fusion, effectively suppressing systematic artifacts and improving temporal coherence—particularly crucial in animation. Through extensive experiments, we demonstrate that our framework enhances temporal stability, visual appearance, and residual error reduction across diverse rendering scenarios.
Towards Secure and Efficient Route Computation for Cross-Chain Message Delivery
(University of Waterloo, 2026-01-29) Rezaei, Amin
Demand for blockchain applications has led to a surge of new public blockchains. However, this fragments liquidity and pushes users to bridge across unfamiliar protocols, increasing risk and complexity. Cross-chain communication enables interoperability, allowing contracts to execute logic and move assets across chains. Yet current delivery solutions either support message passing only between directly connected chains, limiting connectivity, or are centralized and route through a single hub chain that introduces a single point of failure and requires trust in the hub operator. Inter-blockchain communication can become more robust by leveraging concepts from traditional network architectures, including routing, name resolution, and policy-based message delivery. These mechanisms can increase connectivity by enabling chains that are not directly connected to communicate securely over multi-hop routes. This thesis studies the problem of policy-driven cross‑chain routing: Current cross-chain routing is largely ad-hoc and manual, and does not reliably respect users' security or cost preferences when no direct connection exists. Given a dynamic inter‑chain topology and user policies (e.g., security thresholds, fee budgets, latency targets), we compute routes over multi‑hop Inter-Blockchain Communication (IBC) while ensuring (a) security constraints are strictly enforced on-chain and (b) preference constraints (e.g., minimizing gas costs) are met with practical guarantees. This is challenging because the required inputs (e.g., fees, validator sets, congestion, and application-specific state) change independently on each chain, yet the resulting route and its policy compliance must be verifiable on the destination chain at a reasonable cost. We present a modular stack: a Transport Layer with Policy Enforcement Module, a Relayer Control Plane for route computation, and a Relayer Data Plane for execution, which separates concerns between policy specification, route computation, and delivery. We introduce three routing methods: (1) Single‑Relayer routing, which computes routes off‑chain independently by off-chain relayer nodes, (2) zkRouter, which computes routes off‑chain with a succinct zero‑knowledge proof of policy compliance and (3) Relayer Network, a new collaborative overlay that distributes operational load (client updates, packet relaying) across relayers. Our prototypes demonstrate that our stack is practical and achieves higher decentralization, better connectivity, and greater scalability, enabling richer and safer cross-chain applications while preserving IBC’s security assumptions and without significant fee overhead. Our evaluation shows: (1) near 90% connectivity vs. 15% for hub-and-spoke; (2) more than 30% connectivity after removing top four chains, reaching 50% with topology upgrades; (3) less than $0.10 on-chain cost per message; (4) scales to more than 10^6 messages maintaining low processing time.
Monastic Diets and Aquatic Species: Examining Potential Fish Consumption at the Ghazali Monastery, Sudan Through Stable Isotope Analysis of Sulphur
(University of Waterloo, 2026-01-28) Tham, Carita
Stable isotope analysis can be applied in bioarchaeological contexts as a tool to assess paleodiet as this technique relies on naturally occurring differences in isotopic values in different food sources and environments. Previous research has been conducted to assess possible dietary composition of the monastic inhabitants of at the medieval Makurian site of Ghazali (ca. 680-1275 CE), Nubia using stable isotope analyses of carbon (δ13C) and nitrogen (δ15N) on bone collagen of its monastic inhabitants. This showed a varied diet evidently comprising of both terrestrial plants and animals. Additionally, δ15N values observed in five individuals suggest potential aquatic species consumption in conjunction with terrestrial animal protein. However, no remains of aquatic species were identified during excavations at Ghazali, and little aquatic species were identified at other Makurian sites. This lack of evident aquatic species (e.g. fish) consumption at Ghazali brings forth numerous questions surrounding dietary practices both at Ghazali and within the broader region of similar Makurian monasteries. This research utilized stable isotope analysis of sulphur (δ34S) on human bone collagen in conjunction with previously presented δ15N values, in tandem with existing textual and bioarchaeological evidence from Egypt and Byzantium, to determine the presence or absence of fish in the diet of the monastic inhabitants at Ghazali. The sample consisted of 20 individuals from Cemetery 2, where 18 of these individuals were male monks. Analysis of δ34S, when coupled with previous δ15N values, revealed that four of these individuals showed evidence of possible fish consumption alongside terrestrial animal protein consumption.
Utilizing Existing Data to Measure Ecological Connectivity for Planning Southern Ontario’s Urban Growth: A Case Study of the Waterloo Region
(University of Waterloo, 2026-01-27) Wiens, Cassandra
Urbanization is an increasing threat to global biodiversity. Urban areas are often thought to preclude native plants and animals but are capable of supporting some species if properly managed. Urban planning tends to focus on maximizing human benefits of the urban landscape; however, urban greenspaces can enhance ecological services for humans and promote natural species diversity. Habitat quantity and quality should be the top priorities when managing urban greenspaces. In urban areas, quantity and quality may be limited by the area available, so other tools are needed to make advancements. Connectivity represents a metric that could help plan urban greenspaces. To explore the utility of connectivity tools for cities in Southern Ontario, resistance maps were developed for Kitchener, Ontario based on four animals (bats, deer, shrews and snakes) using 2019 aerial data. Scenarios were developed based on potential changes to the city by increasing either the number of habitat cells by 5% or 10% (showing potential backyard and small greenspace restorations) or the number of buildings cells to meet projected growth targets. These were created by selecting cells randomly and reassigning values based on desired fragmentation of the land type. The resulting resistance maps were analyzed using an “omnidirectional” method developed for Circuitscape that enabled landscape level analysis of connectivity. Urban connectivity differed for the four species based on the dispersal capability of each species with bats and deer having the most connectivity with maximum resistance values of 0.53 and 0.76 respectively and shrews and snakes the least connectivity with maximum resistance values of 1.07 and 1.33. Connectivity decreased with increasing urbanization, showing a gradient of increasing current as building density increased and urban green spaces decreased. All urban greenspaces, from yards to natural areas, were important for landscape connectivity and need to be maintained if not enhanced. Buildings represented the primary barrier for all species other than bats (due to their ability to fly over them). Roads and paved areas also posed barriers to all species and represented the strongest barrier for bats. Mitigation methods should be considered for these areas, with greenspaces planned through highly built areas. Of the three models, increased building density had the largest effect on habitat connectivity, changing the resistance values by 25-33% for deer, shrew, and snakes. Bats species only had a 5-6% increase in resistance because buildings are less of a barrier to bats. The models with increasing habitat amounts were difficult to visually differentiate from the 2019 baseline, and changes in resistance value were less than 1%. These maps did show some benefits for urban species. This was expected due to the larger number of cells changed in the increased building density scenario. Planning mitigation efforts around densification should be the top priority for maintaining connectivity, but creating and maintaining greenspaces should not be forgotten as increasing habitat provides benefits beyond connectivity. Overall, these results were expected, but this analysis did show the utility of connectivity mapping for Kitchener. Connectivity analysis is potentially a valuable tool for urban planners in Southern Ontario cities if habitat quantity and quality are already being maximized and with the caveat that connectivity planning should not justify the removal of existing habitat patches and care should be taken to avoid undervaluing small patches.
Mobility and the Landscape: Investigating mobility of individuals at Wadi Faynan 100 using minimally invasive strontium isotope analysis
(University of Waterloo, 2026-01-27) Mah, Jessica
In comparison to other sites in Jordan, life at the Early Bronze Age (~3600-3000BC) site of Wadi Faynan 100 (WF100) is still largely a mystery. To better understand the use of this site in relation to the EBA transformation of social organization toward urbanism, this study explores strontium isotopic variation using laser ablation-multicollector-inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) to observe movement to and from the local area. Strontium (Sr) isotope ratios throughout the developmental periods of human enamel were used to indicate locality and patterns of mobility at WF100. Thirty-one samples consisting of a collection of permanent incisors, premolars, and first and third molars, in addition to two deciduous molars were analyzed alongside eleven local faunal samples. Initial results indicate variable patterns of mobility throughout the individual’s childhood development, with some increased instances of consistent locality in later childhood. This supports arguments for a more diversified and regionally specific social organization in EBA Jordan and Wadi Faynan, that may embrace a spectrum of sedentism and transhumance in childhood. These results highlight both the potential for, and challenges of conducting further LA-MC-ICP-MS analysis of Sr in the broader Jordan landscape and provide novel insights into EBA mobility using sequential dental sampling.
Filter Performance Optimization for Protozoan Pathogen and Particulate Contaminant Removal During Drinking Water Treatment
(University of Waterloo, 2026-01-27) De Silva, Kalani
Physico-chemical filtration (chemically assisted filtration; CAF) remains a critical barrier for the removal of particulate contaminants, including Cryptosporidium oocysts and emerging contaminants such as microplastics, during drinking water treatment. Ensuring consistent CAF performance becomes particularly challenging for systems reliant on high-quality source waters—those with low turbidity and low dissolved organic carbon concentrations—where traditional performance indicators such as turbidity may provide limited insight into the adequacy of coagulation, as source waters often already meet treated-water turbidity criteria prior to coagulation. Under these conditions, coagulant inadequacy or under-dosing may not be readily apparent, potentially resulting in insufficient particle destabilization and overestimation of Cryptosporidium oocyst removal by CAF and associated regulatory treatment credits. The goal of this research was to demonstrate the importance of particle destabilization for achieving reliable removal of protozoan pathogens and other particulate contaminants (including microplastics) by CAF for systems reliant on high-quality source waters. While the importance of coagulation in destabilizing particles for effective CAF is well known, its regulatory and operational relevance—particularly for HQSW—needs to be revisited given the public health importance of drinking water treatment. Pilot-scale performance demonstrations were conducted to: (1) demonstrate the inadequacy of filter effluent turbidity as an indicator of coagulant demand required to achieve ≥3-log protozoan removal by CAF; (2) evaluate zeta potential as an operational tool to indicate the sufficiency of particle destabilization needed to maximize protozoan removal by CAF; (3) investigate direct in-line CAF’s ability to achieve ≥3-log protozoan removal; (4) determine whether removal of microplastics exhibit behavior consistent with other colloidal particles during CAF; and (5) evaluate key methodological factors that contribute to variability and uncertainty in performance demonstrations to enhance confidence in interpreting measured CAF performance. Collectively, the findings reinforce that adequate coagulation and particle destabilization are fundamental drivers of CAF performance across particle types, treatment configurations, and methodological approaches. This work demonstrated that turbidity alone cannot indicate adequacy of coagulant application for high-quality source waters, whereas zeta potential offers a tool to guide coagulant dosing and confirm the particle destabilization needed to achieve ≥3-log protozoan removal by CAF, recognizing that sufficient destabilization range and associated coagulant doses vary with system and water quality specific conditions. At the same time, it also demonstrated performance demonstration methods commonly used to evaluate protozoan removal remain reliable and yield consistent results when particle destabilization is optimized. This work highlights opportunities to strengthen treatment guidance for the removal of protozoan pathogens by CAF for systems reliant on low-turbidity, low-DOC source waters, provides pilot-scale evidence supporting reconsideration of treatment credits assigned to direct in-line CAF, and offers foundational process understanding needed to inform regulatory policy on microplastics.
Semantic Segmentation of LiDAR Point Clouds for 3D Mapping of Underground Space
(University of Waterloo, 2026-01-27) Fatholahi, Sarah N.
Underground space is among the most challenging environments for 3D mapping because the Global Navigation Satellite Systems (GNSS) signals are often inaccessible. This thesis investigates the use of the LiDAR-based Simultaneous Localization and Mapping (SLAM) technology to map such underground space. Underground parking lots, as an example, offer valuable solutions to the challenges posed by growing populations and urbanization, such as limited surface area, traffic congestion, and environmental concerns. They are GNSS-denied, geometrically repetitive, highly occluded by vehicles and pillars, and contain large, low-texture and specular surfaces that degrade sensing and registration. To support rigorous evaluation under these conditions, this thesis contributes three site-specific underground parking datasets captured using a hand-held LiDAR device, GeoSLAM. Each dataset provides clean point clouds and semantic labels for the core structural and operational classes: wall, pillar, vehicle, and ground, enabling controlled benchmarking. Since low-cost LiDAR scans yield sparse, non-uniform point distributions that omit fine structural features, the first study of the thesis addresses point cloud upsampling, an essential step for creating high-definition maps that preserve fine structural details while ensuring uniform data distribution for downstream tasks. Five deep learning upsampling models including PU-Net, PU-GAN, PU-GCN, PU-Transformer, and RepKPU are trained and tested in a unified pipeline and evaluated with Chamfer Distance for average surface fidelity, Hausdorff Distance for worst-case deviation, and inference time for deployability. RepKPU consistently delivers the best accuracy–latency trade-off in underground setting. Since accurate semantic understanding is crucial for structure-aware mapping and autonomous navigation in complex indoor environments, the second and third studies target semantic segmentation for underground parking spaces, first using Transformer-based backbones and then extending the evaluation to Mamba-based architectures. For Transformer-based methods (PT, PCT, and 3DGTN), the generalization across the three different parking lots is assessed using overall accuracy (OA), mean Intersection over Union (mIoU), and F1-score. The results establish 3DGTN as the most accurate and stable Transformer framework across all three sites. Complementing the Transformer study, Mamba-based methods (PointMamba, PoinTramba, and 3D-UMamba) are compared on the same datasets with 3D-UMamba offering the best overall performance.
UEPVGA: A Novel Unreal Engine 5 Based Methodology for Airport Photovoltaic Glare Assessment
(University of Waterloo, 2026-01-26) Lyu, Hongliang
Airports have significant potential for deploying solar photovoltaic (PV) systems because they have large amounts of available land and high energy demands. However, the deployment of PV systems in and around airports in Canada and the United States is constrained by concerns from pilots and ground personnel regarding glare risks and formalized in policy that restricts their deployment without a comprehensive glare risk assessment. To address these issues, we developed a novel Unreal Engine PV Glare Assessment (UEPVGA) framework. The framework uses real-time game engine rendering to create photorealistic, dynamic glare simulations. It employs physically based rendering techniques to model the optical properties of PV modules that accurately reflect the relationship between incident angle and reflectance. Astronomical algorithms precisely simulate the sun's position and trajectory across the sky throughout the year. Simulated glare from the UEPVGA was validated against observational data at different altitudes and angles from real-world PV panels that were acquired by a remotely piloted aircraft. Validation results demonstrated that the simulated solar position and glare intensity of solar panels highly correlate with observational data. The framework was then used to conduct a glare assessment of a study area considering three hypothetical zones for PV panel installations. Results revealed pronounced seasonal risk patterns and identified specific high-risk zones, demonstrating the framework's practical value for operational safety planning. This study suggests the feasibility of using game engines as environmental simulation platforms and highlights their potential to support aviation safety and other fields.
Spectra of Translation-Invariant Function Algebras of Compact Groups
(University of Waterloo, 2026-01-26) Zhang, Zhihao
Let G be a compact group and let Trig(G) denote the algebra of trigonometric polynomials of G. For a translation-invariant subalgebra A of Trig(G), one can consider the completions of A under the uniform norm and the Fourier norm. We show in Chapter 2 using techniques developed by Gichev that both completions have the same Gelfand spectrum, answering a question posed in a paper of Spronk and Stokke. In the same paper, a theorem describing of the Gelfand spectrum of the Fourier completion of finitely-generated such algebras A was given. In Chapter 3, we extend this theorem to the case of countably-generated, translation-invariant subalgebras, A. In Chapter 4, we give a brief overview of the Beurling--Fourier algebra, a weighted variant of the classical Fourier algebra studied by Ludwig, Spronk, and Turowska. The addition of a weight for these particular algebras invites new spectral data in contrast to its classical counterpart. In Chapter 5, we show for Beurling--Fourier algebras of compact abelian groups G that its weight can be used to construct a seminorm on tensor product of the real numbers with the Pontryagin dual of G that remembers the spectral data of the algebra.
Characterization and Comparison of Flammability Properties and Trace Emissions of Select Native and Invasive Canadian Wildland Fire Fuels
(University of Waterloo, 2026-01-26) Lakhani, Ayaan
Fire has played an integral role in the evolution, formation, and sustainability of North American forest ecosystems. Historically, Indigenous peoples have employed fire as a deliberate land management tool to maintain forest health, shape landscapes, and achieve early industrial objectives. With the landing of European settlers, and changes in governmental policy, the use of fire as a land/fuel management tool was greatly diminished. In addition to the suppression of fire as a tool, the intentional and accidental introduction of non-native plant species to Canadian forest ecosystems has dramatically altered its structure from the 17th century through to today. In addition, emissions of CO₂ and other greenhouse gases have been rapidly increasing since industrialization, which has warmed the planet, resulting in extreme weather events like droughts and storms that occur at increasing frequency and severity. This has culminated in wildfire conditions that are drastically different to those that shaped the historical evolution of Canadian forests. Key changes in forest fuels include larger spatial distributions of fuel types and moisture content, which affect fire growth and development. Over the past few decades it has become evident that understanding these factors of fuel types, moisture content, and fire growth and development are critical to improve performance of predictive models, as well as our overall understanding of how to combat and minimize the damage caused by these severe wildfire events. Assessment of wildfires has generally taken two approaches: the first being a largescale analysis of a real wildfire event, which characterizes total emissions and bulk burning behaviour, and the second being small-scale studies that often focus only on one specific fire performance metric or a limited set of emissions. While both approaches have yielded significant data in terms of bulk fire performance metrics and separate emissions data, this separation has led to a dearth of integrated, detailed, and comparative data. This comparative data is critically important because the lack of species-specific flammability metrics and associated detailed emissions data under varying conditions hinders the accurate prediction of fire behaviour and the development of effective land management strategies. Furthermore, the absence of data explicitly linking exposure conditions to trace emission profiles (the toxic fraction of smoke) leads to misestimates in both emission inventories and air quality models, potentially compromising environmental safety assessments. In this research, a pair of native species and a pair of invasive species are tested at small scale for their flammability properties, major, and trace emissions. Testing was conducted under two different levels of fuel moisture and two different radiation exposures, with twelve replicates per condition. The native species are trembling aspen and ironwood while the invasive species are buckthorn and barberry. All four species were tested under reference conditions (35 kW m⁻² incident heat flux, and naturally dry conditions), buckthorn and trembling aspen were tested under elevated heat flux (50 kW m⁻² incident heat flux, and naturally dry conditions), and barberry and ironwood were tested at elevated moisture conditions (35 kW m⁻² incident heat flux, and field-tested moisture conditions). Across the tests, flammability properties, such as ignition delay time and heat release rate, were compared as well as real-time concentrations of CO₂, CO, and VOCs. In addition to these three gases, thermal desorption tubes were employed to sample the smoke plume at three phases during a test – pyrolysis, open flaming, and smouldering – and were analyzed using GC-MS to identify and group key emissions, then develop a qualitative sensitivity of trace emissions to species and burning conditions. To properly frame the discussion surrounding the production of trace emissions, the lignocellulosic compositions (% cellulose, % hemicellulose, and % lignin) and the apparent activation energy of each of the species was determined using thermogravimetric analysis. Finally, inductively coupled plasma-optical emission spectroscopy and X-ray diffraction were employed to identify and quantify metallic emission differences in the post-burn particulate matter and the fire smoke plume. A broad summary of the results shows that species composition (lignocellulosic makeup) and intrinsic physical characteristics (sample piece sizes and packing geometry) are the dominant factors driving differences in fire performance and flammability under reference conditions. When exposed to a higher heat flux, the external energy largely overcame the impacts of geometry, allowing compositional differences to become the sole dominant factor dictating distinct species responses in peak heat release rate and emissions. The exposure to the increased heat flux also greatly reduced the ignition delay time and increased the heat release rates for both native and invasive species. Conversely, increased fuel moisture content led to a clear and consequential shift toward less efficient, incomplete combustion processes, resulting in substantial increases ignition delay time, reductions in heat release rate and increases in CO and VOC emission factors during the pyrolysis, flaming, and smouldering phases. Thermogravimetric analysis confirmed a compositional-kinetic relationship where the apparent activation energy varied by up to 24% across species. This kinetic variation, coupled with data from thermal desorption-gas chromatography–mass spectrometry, highlighted the dependent nature of trace species production on the specific species composition and apparent activation energy. Different species produced distinct groups of trace emissions and showed differing responses to both elevated heat flux (where some experienced volatile suppression and others persistent intermediates) and varying moisture conditions (where smouldering emissions were dramatically amplified or altered).
Electroluminescence in the Classical and Quantum Regime in Undoped GaAs/AlGaAs Heterostructures
(University of Waterloo, 2026-01-26) Harrigan, Stephen
Quantum information processing holds the promise to radically change the way we perform computations and transmit information. In the realm of quantum computing, there has been enormous progress in the last few decades in a huge variety of quantum systems and it is unclear which platform will be the leading system to execute quantum computations. Conversely, photons have always remained the front-runner for the long distance transfer of quantum information since photons travel at the speed of light and have limited mechanisms of decoherence (as compared to other carriers of quantum information) when traveling over long distances. The method used to generate single photons remains the pertinent open question. Current state-of-the-art single-photon sources (SPSs) are optically-active quantum dots driven by an external laser source. For laboratory-scale experiments, they have proven fruitful in order to demonstrate key components of a quantum network, as well as performing fundamental tests on the nature of quantum mechanics. However, one challenge associated with these optically active quantum dots is two-qubit interactions since the quantum dots are usually spatially isolated. Conversely, two-qubit interactions for spin qubits in gate-defined quantum dots is routinely achieved via the Heisenberg exchange interaction. Thus, it would be highly desirable to have a way to convert the quantum information of the spin state of gate-defined quantum dots to photon polarization. Furthermore, for the prospects scaling of the technology, it would be highly desirable for this quantum information transfer to be all-electrical in order to leverage conventional multiplexing techniques. In the first part of this thesis, we outline our proposal for an all-electrical SPS where single-photon emission is driven by electroluminescence (EL) at the single-charge to single-photon level. In order to control carriers at the single-charge level, we propose using non-adiabatic single-electron pumps (SEPs) previously investigated as quantized current sources for metrology. We have also previously developed a lateral p—n junction whose geometry allows direct integration with a SEP. We compare our proposed SPS to existing electrically-driven SPS in the literature, highlighting anticipated strengths of our proposed device, including a fabrication process compatible with standard semiconductor fabrication techniques. Given the key role SEPs play in our proposed SPS, we describe the established theory underpinning the high fidelity operation of SEPs. We also highlight practical considerations for the operation of SEPs, including device fabrication challenges faced during the course of this research, and demonstrate how to measure and characterize a SEP. A secondary focus of this thesis has been investigating EL from lateral p—n junctions in regimes where there was no attempt to control carriers at the single-charge level. While measuring lateral p—n junctions, we noticed an unconventional form of EL that did not require a forward bias to be applied. By swapping the polarity of the top gate voltage of our ambipolar induced devices, existing carriers recombine radiatively with incoming carriers of the opposite charge. Due to the flow of carriers in and out of the device, we called this form of luminescence the tidal effect. We develop a model to explain the non-monotonic frequency-dependent EL intensity and perform temperature-dependent measurements to identify the species responsible for the observed EL. We also further investigate a similar phenomenon when two adjacent top gates are periodically swapped with a phase difference between the two signals. We demonstrate that this form of EL is more efficient over larger areas than the tidal effect, and therefore may be more suitable for general illumination purposes. Lastly, we also performed the first EL measurements from lateral p—n junctions in single heterojunction interfaces. Despite the lack of a bottom barrier in these devices, our measurements suggest that carrier recombination is occurring near the interface. We characterize the EL spectra and observed the so-called H-band, a type of space-indirect exciton created in proximity to a populated single heterojunction interface, which has only previously been observed in photoluminescence experiments. Time-resolved EL experiments suggest reduced dimensionality of neutral excitons. We show that the lifetime of the H-band can be tuned electrically. We also demonstrate that the tidal effect can also be observed in these single heterojunction interfaces.
Designing Public Health Surveillance for Urban Air Quality in LMICs: Community Insights, Technology Acceptance, and System Design for Low-Resource, High Vulnerability Settings
(University of Waterloo, 2026-01-26) Salim, Shahan
Climate change is tightening exposure windows and widening inequalities in urban air quality, especially across low- and middle-income countries. Many cities lack dense regulatory networks, timely analytics, and trusted communication pathways, which means signals arrive after decisions are due. Grounded in Ulaanbaatar, Mongolia, this thesis begins by asking how people make sense of pollution in their daily lives, what actions are realistically available, and which institutions are expected to respond. These lived accounts specify what usable guidance must deliver in contexts where resources are limited and risks are uneven. Guidance must be fast, intelligible, transparent about uncertainty, and aligned with social roles and constraints that vary. A second qualitative strand examines technology acceptance of digital monitoring and early warnings. It identifies what confers legitimacy, including credible data provenance, visible accountability, and delivery pathways that match capabilities such as low connectivity, limited time, and competing obligations. Together, these qualitative insights establish system requirements and the conditions under which guidance is likely to be acted upon. Based on these insights and in partnership with UNICEF Mongolia, the thesis designs, develops, and evaluates a real-time air quality pipeline for Ulaanbaatar. Low-cost sensors feed an automated device to database workflow that stabilizes sparse and noisy inputs. A sequence modeling approach produces continuous predictions with calibrated error suitable for communication and decision support under intermittent power and limited connectivity. Evaluations suggests the system performs reliably under these constraints and can be adopted within existing civic workflows. The integrated contribution is a pathway from qualitative insights to deployable infrastructure that supports proportional protection. The thesis advances empirical understanding of disproportionate risks in an LMIC city, delivers a validated and operational monitoring and prediction pipeline build from locally derived requirements, and offers policy and design guidance that ties technical accuracy to local relevance and shared accountability so that evidence arrives in time to reduce harm.
Novel Class Discovery for 3D Point Cloud Semantic Segmentation in Large-Scale Environments
(University of Waterloo, 2026-01-23) Du, Jing
Modern urban environments undergo continuous transformation as emerging infrastructure appears worldwide. Traditional semantic segmentation methods for 3D point clouds operate on fixed taxonomies, producing static representations that cannot adapt to novel categories. This dissertation addresses novel class discovery (NCD) in large-scale 3D point cloud segmentation through geometry-aware mechanisms, adaptive multi-source fusion, and hybrid supervision frameworks. The first study establishes geometric foundations through voxel-geometry integration with region-centric organization, termed CHNCD. The framework couples voxel representations with original spatial coordinates via index mapping, identifies semantically informative points within clusters, accelerates neighbor retrieval through proximity hash mapping, and consolidates localized features with global context via spatial attention. Experiments on S3DIS, Toronto-3D, SemanticSTF, and SemanticPOSS demonstrate consistent improvements over discovery baselines. The second study deepens representation through adaptive geometric sequence modeling, dynamic Gaussian embeddings, and gated multi-source fusion, termed AGDNet. Adaptive geometric sequence modeling employs learnable dimension weighting and dynamic grouping adjusted to local point density. Dynamic Gaussian embeddings represent point clouds as 3D Gaussians and compute Mahalanobis distances to generate multi-scale spatial embeddings. Gated multi-source fusion intelligently weights features through context-aware mechanisms. Three knowledge-transfer objectives operate at category, instance, and distribution levels to bridge semantic gaps. Evaluation on Toronto-3D, SemanticSTF, and SemanticPOSS demonstrates substantial improvements. The third study integrates discovery with operational land cover mapping, termed 3DLCDM. The framework processes features through a supervised head for established categories and a dual unsupervised head comprising a primary branch with fixed prototypes and an over-segmentation branch with progressive scheduling. Temporal Sinkhorn-Knopp normalization with adaptive temperature scheduling stabilizes pseudo-labels, while dynamic weighting combines per-batch and global frequency statistics to address class imbalance. Evaluation on DALES and H3D datasets demonstrates substantial improvements for continuous land cover discovery mapping. Taken together, the three studies advance a progressive research agenda unifying discovery and 3D segmentation for large-scale point cloud scenes. The dissertation demonstrates consistent gains across six benchmark datasets, exhibits generalization across sensors and acquisition geometries, and provides a principled route to maintain updated urban maps as new structures emerge.
Signals of Legitimacy or Tools of Strategy? Investigating ESG Score Drivers in the Age of Sustainability Accounting Standardization, an Analysis of Canadian Firms
(University of Waterloo, 2026-01-23) Scarfone, Joseph
ESG scores non-financial reporting sustainability reporting legitimacy theory TSX firms positive accounting
How Gender Shapes Youth Perspectives on the Health Impacts of Urban Design in High-Rise Environments
(University of Waterloo, 2026-01-23) Asafo-Agyei, James Kusi
This thesis investigates how urban design in high-rise neighborhoods shapes adolescent health, with a particular focus on gendered experiences. Guided by an adapted framework from the CIP Healthy Communities guide and using the Gender-Based Analysis Plus (GBA+) lens, the study identified neighborhood spaces where youth engage in health-related activities and examined how gender influences youth perceptions of urban design and its impact on physical, mental, and social well-being. A participatory qualitative methodology was employed, involving 22 adolescents also described as youth or teens aged 13–18, from two Ontario cities using ‘go-along’ interviews and participant-directed photography. Thematic and content analysis revealed that parks, recreational centers, and urban public spaces serve as key sites for youth health engagement. Boys reported greater ease accessing sports and outdoor spaces, often taking safety and mobility for granted, while girls expressed heightened concern over sanitation, environmental stressors, and personal safety. These findings demonstrate how gender and spatial design intersect to create unequal health experiences for adolescents. The study calls for gender-responsive urban planning that centers youth voices and promotes inclusive, safe, and accessible high-rise environments that support holistic adolescent well-being.
Mine Tailings as Sources of Greenhouse Gas Emissions: A Multi-Site Investigation Incorporating Isotopic Signatures
(University of Waterloo, 2026-01-23) Wang, Jiahe
Tailings are the slurry waste product from mining operations deposited in impoundments in large quantities and are associated with challenging environmental issues such as acid mine drainage. Sulfide-rich tailings can be oxidized due to O2 ingress and water infiltration, producing H+ that dissolves surrounding carbonate minerals, leading to CO2 production. To characterize the seasonal CO2 emissions from tailings impoundments with various cover systems and explore the geochemical and physical controls on the emissions, field studies were conducted at five mine tailings sites in Canada. The sites included tailings that are uncovered (Giant Mine, NT), sand/gravel-covered (South Bay Mine, Long Lake Mine, and Nickel Rim North Tailings, ON), and multi-layer-covered with O2-consuming-organic material and desulfurized tailings (Strathcona Tailings Management Area, ON). Physical properties were measured and analyzed including tailings water content, soil temperature, particle density, and porosity. Tailings solid and pore water samples were collected via manual coring and squeezing extraction from core samples. Gas depth profile sampling and gas flux chambers were used to quantify subsurface gas concentrations and CO2 fluxes in the subsurface and to the atmosphere. To characterize the stable carbon isotope signatures across phases and source-trace CO2 transport, the δ13C values of solid, aqueous, and gaseous phases in the investigated tailings systems were determined. At uncovered and sand/gravel covered sites with high sulfide content, acidic conditions (pH <2), rapid O2 depletion, high subsurface CO2 concentrations (>20 vol.%), and substantial surface fluxes (up to 140 kg ha-1 day-1) to the atmosphere were measured. Effective covers (composite desulfurized tailings/organic materials) suppressed acid generation but still sustained considerable CO₂ fluxes to the atmosphere (~100-120 kg ha⁻¹ day⁻¹). Sites rehabilitated with different cover systems showed CO2 fluxes in June and July that were twice as high compared to September and October. δ13C values (-4‰ to +3‰) of pore-gas CO2 samples suggest that CO2 originated from geogenic carbonate mineral dissolution at the sand/gravel-covered site. At the multi-layer-covered site, the δ13C-CO2 values of <-20‰ in the organic material cover and -10‰ to -5‰ in the deeper desulfurized tailings, suggest mixed sources of CO2 production. This study demonstrates that tailings emit CO2 at rates exceeding or comparable to wetlands, forests, and farmland sites. A large portion of the CO2 is derived from primary carbonate minerals contained within the mine wastes. Integrating CO2 emissions into global C budgets is critical, and future cover designs must balance remediation control with C management to mitigate climate impacts.

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