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Recent Submissions
Assessment of the Proposed Policies for a Carbon Capture and Storage Regulatory Framework in Ontario
(University of Waterloo, 2025-02-21) Kim, Duckhoon
Since 2022, Ontario has been investigating the possibility of developing a Carbon Capture and Storage (CCS) framework as they aim to reduce carbon emissions and align with the federal government’s goals of net-zero emissions by 2050. This CCS regulatory framework should focus on hard-to-abate sectors where alternative renewable energy technologies are in their early stages, or they are difficult to be transitioned. However, within the research field of CCS in Ontario from a policy perspective, there are minimal journal articles and grey-literature documents that discuss this topic. Therefore, the purpose of this thesis is to understand and analyze Ontario’s proposal of their regulatory framework for CCS and to give recommendations to the CCS framework by comparing it against the information gathered from other jurisdictions (Alberta, Saskatchewan, the United States, Europe and Australia). Key research questions are 1. How can the knowledge gained from other regions regarding CCS help Ontario's hard-to-abate sectors to understand approvals, licensing, and liability? 2. What are some other necessary policies that Ontario would need to expand upon and potentially adopt from various jurisdictions? And 3. How did companies and governments in other jurisdictions communicate to the public about the need for this technology? The thesis first developed a literature review to compare and contrast policies from other jurisdictions by researching and synthesizing various peer-reviewed journal articles and grey literature. Then, a semi-structured interview was needed to explore any unique perspectives from interviewees with expertise in CCS, and also to understand whether the results aligned with the information from the literature review. Following the interviews, the analysis of the results were accomplished by using ‘codes’ and ‘themes’, which allows for a simplified understanding of which information is unique. As a result, there were unique findings from the interviews such as ensuring proper industries are utilizing CCS, explaining the purpose of CCS, ensuring that the regulatory framework for CCS is properly developed, and the potential for CCS to utilize a carbon market through an Emissions Trading System (ETS). In November 2024, Ontario introduced Bill 228, which contains an Act called the Geologic Carbon Storage Act, 2024. This Act contains the key core components of the regulatory framework, such as ownership, liabilities, and approvals and assessments. As a result, a description and analysis of this Act was undertaken to understand how it compares against my research findings. In conclusion, to answer the first research question, the findings resulted in requiring Ontario to vest in the pore space, implement a unitization statue, implement a transfer of liabilities once certain pre-conditions are met and a post-stewardship fund to cover liability costs. As for the second research question, the other necessary policies include expanding upon environmental assessments methods, using a systems analysis approach to understand the outcomes of developing CCS, incorporating CCS into carbon pricing schemes, and Ontario’s plans on how they should utilize their CCS. The findings for the final research question recommend that the Ontario government and companies recognize the social demographic backgrounds of Ontario; ensure that Ontario is integrating and engaging with communities closely; explaining the downsides of not developing a CCS project; and respecting a community’s decision if they do not wish to engage with the project. Bill 228 is consistent with these findings, namely the inclusion of a liability transfer; a stewardship fund to cover the liabilities for the Crown; unitization of pore spaces; risk management; monitoring, measurement and verification (MMV); emergency response; and various approvals and assessments. However, the ownership of pore spaces deviates from these findings, as Ontario vests pore ownership to the surface owners but still allows the Crown to vest in the pore space when required.
Reweighted Eigenvalues: A New Approach to Spectral Theory beyond Undirected Graphs
(University of Waterloo, 2025-02-21) Tung, Kam Chuen
We develop a concept called reweighted eigenvalues, to extend spectral graph theory beyond undirected graphs. Our main motivation is to derive Cheeger inequalities and spectral rounding algorithms for a general class of graph expansion problems, including vertex expansion and edge conductance in directed graphs and hypergraphs. The goal is to have a unified approach to achieve the best known results in all these settings.
The first main result is an optimal Cheeger inequality for undirected vertex expansion. Our result connects (i) reweighted eigenvalues, (ii) vertex expansion, and (iii) fastest mixing time [BDX04] of graphs, similar to the way the classical theory connects (i) Laplacian eigenvalues, (ii) edge conductance, and (iii) mixing time of graphs. We also obtain close analogues of several interesting generalizations of Cheeger’s inequality [Tre09, LOT12, LRTV12, KLLOT13] using higher reweighted eigenvalues, many of which were previously unknown.
The second main result is Cheeger inequalities for directed graphs. The idea of Eulerian reweighting is used to effectively reduce these directed expansion problems to the basic setting of edge conductance in undirected graphs. Our result connects (i) Eulerian reweighted eigenvalues, (ii) directed vertex expansion, and (iii) fastest mixing time of directed graphs. This provides the first combinatorial characterization of fastest mixing time of general (non-reversible) Markov chains. Another application is to use Eulerian
reweighted eigenvalues to certify that a directed graph is an expander graph.
Several additional results are developed to support this theory. One class of results is to show that adding $\ell_2^2$ triangle inequalities [ARV09] to reweighted eigenvalues provides simpler semidefinite programming relaxations, that achieve or improve upon the previous best approximations for a general class of expansion problems. These include edge expansion and vertex expansion in directed graphs and hypergraphs, as well as multi-way variations of some undirected expansion problems. Another class of results is to prove upper bounds on reweighted eigenvalues for special classes of graphs, including planar, bounded genus, and minor free graphs. These provide the best known spectral partitioning algorithm for finding balanced separators, improving upon previous algorithms and analyses [ST96, BLR10, KLPT11] using ordinary Laplacian eigenvalues.
Imagining Shared Food Futures: honouring Canada's obligations towards Anishinaabek foodways
(University of Waterloo, 2025-02-20) Koberinski, Jodi
Sustainability scholars characterize climate breakdown and biodiversity loss as converging crises tied directly to settler colonial ‘resource management’ regimes. Canada gestures toward mitigating these crises by ‘including’ Indigenous knowledges in environmental impact assessments and policy. Canada prioritizes commodity market profitability over mitigating these crises by excluding Indigenous knowledges in resource management decisions when acting on that knowledge would disrupt industry-favoured practices. One such practice is glyphosate use in forest ‘management.’ Glyphosate is a broad-spectrum agricultural herbicide repurposed to ‘manage’ regrowth after clearcutting forests. Banned by Quebec in 2001, Ontario embraced this practice. In 2013, Anishinaabek Elders along the north shore of the Great Lakes formed the Traditional Ecological Knowledge Elders to campaign for a moratorium on glyphosate use, which is counter to Anishinaabek environmental governance. Proponents claim herbicide use speeds stand regeneration, yet that regeneration converts food-bearing forests to pine plantations. Ontario legislators are not seeing the forest for the trees.
This dissertation contributes to radical food geographies scholarship by characterizing the cumulative impacts of forestry policies on Indigenous foodways. Foodways include economic, material, linguistic, spiritual, intergenerational, scientific, ceremonial, and social dimensions of a culture’s food governance. This study concludes that efforts to imagine shared food futures in Canada’s settler colonial context require reframing ‘renewable’ resource extraction as Indigenous foodways disruption. Applying case study and participatory action research methods, I offer three manuscripts that together characterize the limitations of settler colonial knowledge in imagining shared food futures that meet settler treaty obligations. These three studies conclude that converting Anishinaabek food-bearing forests to pine plantations undermines the conditions required for Canada to meet treaty obligations to protect Anishinaabek foodways.
In the first manuscript, I adapt Vivero Pol’s multi-governance framework to Canada’s settler colonial context to analyze customary and contemporary Indigenous food initiatives through a food commons lens. This study reveals the limitations of settler colonial frameworks for imagining shared food futures. The second manuscript seeks to overcome these limitations by centring an Anishinaabek research paradigm in collaboration with Traditional Ecological Knowledge Elders of the North Shore of Lake Huron. Our case study examining the cumulative impacts of changes to forestry legislation on Anishinaabek foodways centres TEK Elders’ efforts to stop glyphosate use in forestry. Reflecting on Ontario’s Bill 197, we characterize the limitations of settler colonial knowledge systems for understanding the impacts of forest ‘management’ decisions on settler treaty obligations. To better understand the limitations raised in the first two manuscripts, I apply participatory action research methods in the third manuscript to analyze transcripts from the Canadian Society of Ecological Economics’ bi-annual conferences I co-organized between 2019 and 2021. I ask what Indigenous knowledge holders have to say about the repackaging of Indigenous concepts by sustainability researchers within colonial knowledge systems. Despite gestures towards ‘inclusion’ of Indigenous knowledge, settler colonial frameworks depoliticize Indigenous resistance and resurgence, often reinforcing colonial narratives of land cessation and dispossession. Without addressing the underlying settler colonial assumptions and structures, sustainability scholars and settler governments relying on their research risk replicating the violence inherent in food policy frameworks built on settler supremacy. Collectively, these manuscripts identify actions settler colonial scholars have the responsibility to take up, beginning with transforming settler colonial narratives.
On Spoken Confidence: Characteristics of Explicit Metacognition in Reasoning
(University of Waterloo, 2025-02-20) Stewart, Kaiden
In this thesis, I assess how explicit, subjective evaluations of confidence influence monitoring and control (i.e., metacognitive) processes in reasoning. Metacognitive processes play a crucial role in modern dual-process theories of reasoning and decision-making, the consequences of which have been implicated in numerous significant real-world decisional outcomes. It is tacitly assumed that monitoring one’s reasoning for the purpose of optimal deployment of controlled, deliberative processing functions similarly to monitoring one’s reasoning for the purpose of providing a judgment of confidence, despite evidence from other domains indicating otherwise. This thesis takes a critical step toward evaluating metacognitive theories of reasoning and their broader application by assessing the degree to which standard approaches represent realistic accounts of metacognitive processes. To aid in interpretation of the work directly testing this possibility, I first present six experiments addressing foundational issues with respect to the operation of metacognition in reasoning. Chapter 2 provides evidence for a causal relationship between confidence judgments and controlled behavior (specifically deliberation), a reality often assumed in the absence of direct evidence. I demonstrate across four experiments that processing manipulations affect confidence and influence control behavior, consistent with a causal relationship, but also that it is possible to target control behaviour without mirroring effects on confidence. Chapter 3 develops a simple predictive model of confidence that identifies heretofore unidentified, item-based predictors of confidence. This simple model allows a unique approach to testing the central question in Chapter 4. Chapter 4 investigates whether the relationship between confidence and controlled behavior partly depends on the requirement to make explicit confidence judgments. Using a paradigm adapted from research involving nonhuman primates, I compare implicit and explicit confidence conditions. Results reveal small differences in controlled behavior and substantial differences in monitoring. In the present thesis, I provide evidence of plausibly systematic influences of common measurement approaches on reasoning. To this effect, it is likely that the reasoning processes in which individuals engage in day-to-day life are reliably different than those commonly assessed in the lab. This has practical, but also theoretical implications which I discuss.
Wideband Signal Generation at Millimeter-Wave and Sub-THz Frequencies
(University of Waterloo, 2025-02-20) Su, Zi Jun
The rise of sixth-generation (6G) wireless technology has created a need for wideband signal generation at high radio frequencies (RF). However, current digital-to-analog converters (DACs) face limitations, offering either wide bandwidth with low resolution or high resolution with limited bandwidth. This thesis proposes two methods that utilize multiple DACs to generate multiple narrowband sub-bands of a wideband signal, that are combined to produce the desired wideband signal. These methods employ distinct digital processing approaches tailored to specific applications, such as instrumentation or real-time Orthogonal Frequency Division Multiplexing (OFDM) signal generation.
To address non-idealities in frequency-stitching-based transmitters, a frequency-domain calibration technique using multi-tone signals is introduced. Experiments at X-band (9.6 GHz) and D-band (129.6 GHz) validate these methods, demonstrating up to 8 GHz bandwidth and achieving an error vector magnitude (EVM) as low as 0.3\% for a 7.2 GHz 256-QAM OFDM signal. A comparative study of three signal generation approaches—direct Arbitrary Waveform Generator (AWG) generation, baseband in-phase and quadrature (IQ) generation with up-conversion, and frequency stitching—shows EVMs of 1.5\%, 0.8\%, and 1\%, respectively, for an 8 GHz OFDM signal.
A novel architecture using phase-coherent IQ-DACs and mixers for each sub-band is also presented. Calibration using non-uniformly interleaved tones corrects IQ imbalances and distortions, enabling the generation of a 256-QAM OFDM signal with 12 GHz bandwidth at D-band (149 GHz) and achieving a peak data rate of 96 Gbps. Calibration improves EVM and normalized mean square error (NMSE) from 82.6\% and 23.8\% to below 2\% and 1\%, respectively. Additionally, D-band amplifier linearization with a 4 GHz modulation bandwidth improves adjacent channel power ratio (ACPR) from -27.8/-26 dBc to -42.8/-43.1 dBc and EVM from 8.5\% to 1.2\%.
Finally, two architectures for sub-band combination are compared. One generates a wideband signal at intermediate frequency (IF) and up-converts it, while the other up-converts narrowband IF signals and combines them. The second approach demonstrates superior ACPR at high IF power levels, enhancing ACPR by up to 8 dB when generating a 1.2 GHz modulated signal at 142.5 GHz.
These results highlight the efficacy of the proposed methods for generating and linearizing high-quality wideband signals, supporting advanced applications in millimeter wave and sub-THz frequency bands for 6G technologies.