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Recent Submissions

Access status: Embargo ,
Terrain-Adaptive Compensation for Rover Wheel-Slip with Controllers Selected by Quality Diversity
(2026-05-29) Grant, Jasper; Yes; Master of Applied Science; Department of Electrical & Computer Engineering; Not Applicable; n/a; Not Applicable; Jason Gu; Hany El Naggar; Mae Seto
Wheel-slip in planetary rovers creates localization error, wasted power, worn tires and occasionally, mission failure. While wheel-slip estimation and sensing has advanced, active online compensation for wheel-slip has received less attention. Existing approaches use real-time terrain measurements or respond to proprioceptive feedback with only adjusted wheel speeds and torques. Therefore, there is potential to improve proprioceptive-only strategies by not only leveraging wheel speeds, but also potentially steering angles and active suspension, to actively respond to slip. A solution which uses these additional inputs is not confined to conventional driving and can consider unconventional gaits such as ``walking” or ``inch worm” style locomotion. Unconventional gaits can increase the range of navigable slopes beyond limits established by previous rovers. Despite their improved performance, unconventional gaits still rely on terrain parameter knowledge. Existing physics-based models also require knowledge of the soil properties of the navigated terrain. A proposed two-stage offline then online learning framework generates wheel-slip compensation controllers that are not confined to conventional gaits and iterates until a controller is identified to be high-performing on the terrain considered without directly sensing the terrain parameters. Results of this adaptation successfully converge on controllers that perform well on the simulated terrain. This contribution includes a software framework to evaluate and validate rover wheel-slip compensation solutions on realistic deformable terrain. Future work will trial this system on a rover model on real terrain.
Access status: Open Access ,
Artificial Neural Network Applications for Investigating Microwave Radiative Transfer in Polar Environments
(2026-06-02) Henschel, Colleen; Not Applicable; Doctor of Philosophy; Department of Physics & Atmospheric Science; Not Applicable; Dr. Randy Scharien; Not Applicable; Dr. Thomas Trappenberg; Dr. Glen Lesins; Dr. Thomas J. Duck
Accurate retrievals of surface and atmospheric parameters in polar regions are essential for climate monitoring, yet these environments pose unique challenges for remote sensing. Snow and ice exhibit strong spatial and temporal variability in properties such as depth, density, and grain size, leading to large variations in microwave penetration depth which complicates the interpretation of passive microwave satellite observations. This variability, combined with limited in situ observations, makes polar regions particularly difficult to characterize using traditional retrieval methods. This thesis explores whether Artificial Neural Networks (ANNs) can improve retrievals of geophysical parameters from passive microwave observations made by the Advanced Technology Microwave Sounder (ATMS), while also using these retrievals to investigate the physical properties of snow and ice. The study develops and validates two ANN-based retrieval approaches: a single-pixel Multi-Layer Perceptron (MLP) model and an image-to-image Swin-UNet model, which incorporates spatial context. Both models are trained using RTTOV-simulated brightness temperatures and validated against independent ground-based datasets, including measurements made by radiosondes, pyrgeometers, and ice mass balance buoys. The single-pixel retrievals demonstrate strong agreement with in situ observations for atmospheric profiles, emissivities, and frequency-dependent effective surface temperatures, while the image-to-image model further improves spatial coherence and retrieval stability by exploiting spatial structure in satellite swaths. Comparisons with ERA5 show that these ANN approaches often achieve comparable performance using this single-instrument retrieval, while also providing additional surface information in the effective surface temperatures and effective emissivities at lower frequencies. Finally, the retrieved effective surface temperatures and emissivities are compared to physics-based radiative transfer simulations using the Improved Born Approximation (IBA) and the Snow Microwave Radiative Transfer (SMRT) model. These comparisons demonstrate that the ANN retrievals encode physically meaningful information about snow. In particular, the 23.8 GHz effective surface temperature can be used as a proxy for the snow-ice interface temperature for snow-covered ice, while the 183.3 GHz effective surface temperature provides a reasonable approximation for the snow-air interface temperature, thereby providing estimates of the snow temperature gradients. Additionally, the retrieved emissivities can be used to interpret surface and snowpack conditions, where their frequency-dependent behaviour reflects physical changes in the surface state, providing qualitative indicators of evolving snow and ice surface conditions. By capturing the physical relationships between microwave emissions and snow properties, these ANN-based retrievals open new avenues for monitoring polar environments and refining our understanding of their role in the Earth’s climate system.
Access status: Open Access ,
Comprehensive Study of LFP and LMFP/Graphite Lithium-ion Batteries
(2026-06-02) Yue, Meng; Not Applicable; Doctor of Philosophy; Department of Physics & Atmospheric Science; Not Applicable; Dr. Karim Zaghib; Yes; Dr. Michael Metzger; Dr. Penghao Xiao; Dr. Jeff Dahn
Although phosphate-based cathodes are valued for their safety and low cost, their lifetime remains limited by capacity fade associated with lithium inventory loss and transition-metal dissolution. This thesis integrates the author’s published and unpublished work to investigate the degradation of LFP/graphite and LMFP/graphite lithium-ion cells. Electrochemical, physical, and chemical techniques, including cycling tests, impedance spectroscopy, X-ray fluorescence, and liquid-phase NMR, were used to study degradation at elevated temperatures. The results show that cell degradation is strongly influenced by electrolyte additives, salt chemistry, electrolyte quantity, and residual N-methyl pyrrolidone from electrode manufacturing. Increasing vinylene carbonate (VC) suppresses Fe deposition on graphite and improves the lifetime of LFP/graphite cells. In contrast, higher VC content accelerates Mn deposition in LMFP/graphite cells, highlighting the greater complexity of transition-metal dissolution in LMFP systems and the need for further electrolyte optimization to extend cell lifetime.
Access status: Embargo ,
Using fats and combined anti-methanogenic feeding strategies to modulate the dairy microbiome and reduce enteric methane emissions
(2026-05-29) Foster, Jacob; Not Applicable; Master of Science; Department of Animal Sciences and Aquaculture; Received; Dr Anne Laarman; No; Dr Natalie Diether; Dr Rhea Lumactud; Dr Stephnanie Collins; Dr Renée Petri
As the Canadian diary industry aims to achieve net-zero emissions by 2050, anti-methanogenic feeding strategies are needed to reduce enteric methane. This research utilized two approaches to investigate how dietary strategies influence rumen microbial communities and fermentation characteristics associated with methanogenesis. Experiment one used a linseed-based product (LP) and a semi-continuous in vitro model to test increasing dietary inclusion levels of LP. Addition of LP did not reduce methane production or alter fermentation dynamics or microbial populations. Experiment two used an in vivo approach to assess the addition of cultivated red seaweed in TMR diets. Seaweed inclusion did not affect rumen pH or overall microbial diversity. However, there were differences in beta diversity and relative abundances. Likewise, methane was reduced with the addition of cultivated seaweed to TMR diet. Using both in vitro and in vivo methods provides insight into how dietary strategies can reduce emissions from the dairy industry.
Access status: Open Access ,
DESIGN AND CONSTRUCTION OF GENETIC CIRCUITS FOR ENGINEERING METHYL SELECTIVE DNA BINDING DOMAINS
(2026-05-29) Cucksey, Jordan; Not Applicable; Master of Science; Department of Biochemistry & Molecular Biology; Not Applicable; na; Not Applicable; Dr. K. Vanya Ewart; Dr. Barbara Karten; Dr. James M. Kramer; Dr. James Davey
DNA methylation is a crucial epigenetic modification that modifies protein-DNA interactions and regulates many essential processes in prokaryotes and eukaryotes. Control over DNA methylation has applications in disease characterization and treatment, memory-based genetic circuits, and cellular reprogramming. However, current approaches to studying and modifying DNA methylation lack the ability to selectively target methylated sequence-specific DNA. Furthermore, the conventional protein engineering workflow for designing DNA-binding proteins with methyl-selective, sequence-specific DNA recognition relies on inefficient multi-step screening processes. To address these limitations, a genetic circuit is proposed as a high-throughput selection platform for engineering sequence-specific, methylation-selective DNA-binding domains. The pCD plasmid was designed to present a helix-turn-helix repressor library with both methylated and unmethylated operators, and to integrate methylation-selective DNA recognition into an output that could be interrogated by GFP screening and kanamycin resistance selection. The pCD plasmid was successfully constructed using PCR-based DNA assembly of modular circuit components. Kanamycin growth results supported the use of kanamycin resistance as a selection marker to evaluate the binding specificity of engineered DNA-binding domains. The initial failure to establish circuit controls suggested the incorporation of a non-functional repressor construct, Rz. A simplified plasmid, pAD.02, was designed to further investigate the interaction between RZ and the corresponding operator, ZZ. RZ variants, XSN, XAN, XKR, and KSX were paired with TTA, TGT, GAC, and CGG operators, respectively, based on previously characterized LacI DNA-binding-domain operator interactions. These interactions were assessed across the proximal, core, and distal operator positions and revealed that the established LacI DNA-binding domain-operator pairings are not fully compatible within the RZ architecture. In total, 14 functional RZ-ZZ operator pairings were identified and can be incorporated as regulatory components in pCD. Overall, this work advances the development of a genetic circuit-based screening and selection platform for engineering methyl-selective DNA-binding proteins and suggests that surrounding structural features may influence DNA binding domain-operator interactions.
Access status: Open Access ,
Current measurements in the Drake Passage
(1972) Foster, Leslie Alexander; Not Applicable; Master of Science; Department of Oceanography; Not Applicable; unknown; Not Applicable; Dr. D. J. Lawrence; R.R. Lively; C.R. Mann
As part of the Hudson 'TO Expedition, an array of 12 current meters was moored in the Drake Passage near longitude 68° W for 10 days in February, 1970. A hydrographic section was run across the passage at the beginning and end of the mooring period. The geostrophic currents using assumed levels of no motion gave results similar to past studies. The current meter records indicated that a minimum velocity is found in the middle of the water column and they also showed the presence of a semi-diurnal tidal component. The best compromise between the current meter data and the hydrographic data is a variable level of no motion with a net transport qf 5 sverdrups toward the west, but because of lack of current meter data at the convergence zone, an unambiguous transport figure could not be determined.