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Gwen Erdmann - Abstract 24 - Innovate Conference 2025
No full textAcute pediatric illnesses can be challenging for parents to understand and manage. Over the past 20 years we have co-developed innovative arts-based digital knowledge translation (KT) tools with parents to share complex health information and support informed decision-making
Optimizing Battery Price Arbitrage in Alberta’s Electricity Market
No full textThis thesis employs a mixed‐integer linear programming (MILP) framework to explore how battery‐based systems, equipped with vehicle‐to‐grid (V2G) capabilities, can manage charging and discharging schedules in order to minimize, or even reverse, their net electricity costs under varying price conditions. The analysis begins with a single electric vehicle (EV) that is required to maintain 80% of its battery state of charge (SOC) for daily use. Through a cost‐minimization approach, the EV draws energy during lower‐price windows and returns stored energy back to the grid, under V2G, during peak pricing, potentially deriving its net cost below zero. The system constrained is then loosened by shifting the analysis to a fleet of electric buses (EBF), each with a larger battery yet bound by strict route timetables. Although these buses have greater storage capacity, enabling them to take advantage of price spreads, their scheduled service hours often coincide with higher pricing windows, limiting opportunities to fully optimize charging or discharging. As a result, notable cost reductions are achieved, but the magnitude of these savings is largely determined by how effectively off‐peak and on‐peak price intervals align with their operating times. Finally, the thesis analyzes a data center that is free from mobility requirements and maintains a large‐scale battery system perpetually connected to the grid. Unlike the EV and buses, the data center has no fixed operating windows to satisfy; it continuously monitors real‐time electricity prices and adjusts its charging and discharging accordingly. By exploiting the largest price spreads, the data center achieves the lowest overall net cost among the three systems, underscoring how full‐time grid access and higher storage capacity amplify the benefits of arbitrage. All these results show that when a MILP model is used, an adaptive and price‐responsive charging strategy can transform battery systems from mere loads into revenue‐generating assets, whether in personal vehicles, fleet applications, or large‐scale computational facilities
Ionospheric Feedback Instability in Magnetospheric Field Line Resonances and the Ionospheric Alfvén Resonator
No full textThe ionospheric feedback instability (IFI) has been widely proposed to explain the formation of narrow filaments of precipitation in discrete auroral arcs, and even the spontaneous formation of auroral arcs at scales approaching the electron skin depth in the ionosphere. Nearly all published theory ignores the complex interaction between waves and the ionosphere by replacing the latter with a highly idealized height-integrated conductivity (HIC) flat sheet. This oversimplified approximation of the ionosphere is challenged in this thesis by asserting that the real physical system rarely, if ever, matches the requirements for the validity of the HIC model. To prove the assertion, analytic and computational models of coupling between waves and observationally constrained empirical models of the ionosphere are adopted to explore the physical consequences of adopting a more realistic ionosphere in IFI theory.
The thesis begins with one-dimensional (1-D) eigenmode analysis in which the linear dispersion relation of the IFI is derived, accounting for wave parallel electric fields, the magnetospheric convection electric field, and wave propagation within the ionosphere. For representative cases, growth rates are found to be much weaker compared to those obtained under the HIC model assumption. Stabilization is also stronger in shorter systems compared to longer systems, reflecting the faster evolution of wave processes in short systems. To overcome limitations of 1-D eigenmode analysis, a two-dimensional (2-D) multifluid simulation is deployed to investigate the IFI in configurations under the HIC approximation and with plasma dynamics in the E layer spatially and temporally resolved. The results obtained show that the IFI develops only under the flat sheet approximation and is stabilized by strong vertical ion flow velocity shear in a more realistic inhomogeneous ionosphere. It is also found that the development of the IFI in a non-periodic system is convective rather than absolute.
To investigate convective growth of the IFI analytically, an analysis based on a 2-D box model system is conducted under the HIC sheet approximation. The evolution of an injected pulse of shear Alfvén waves impinging on a Gaussian-shaped envelope of localized HIC conductivity perturbation is studied using a Green’s function approach, which reveals characteristic features of the evolution of the IFI, including spatial growth and ultimately damping of the excited disturbances after they have propagated relatively far from the source of their excitation, a situation further exacerbated by the effects of ionospheric inhomogeneity. The results of the thesis challenge the long-established theory of the IFI by demonstrating that for the spatially resolved ionospheric conditions specified, the instability is hard to achieve and unphysically overestimated under the height-integrated flat sheet conductivity approximation
Multi-Variable Implementation Optimization of Dual Active Bridge Converters Considering Multi-Objective Trade-Offs Between Cost and Efficiency
No full textThis thesis presents a comprehensive optimization framework aimed at improving
both the efficiency and cost-effectiveness of Dual Active Bridge (DAB) converters.
The efficiency and reliability of DAB converters strongly depend on multiple implementation
variables, such as gate drive voltages, gate resistances, snubber capacitances,
number of parallel switches, and dead time. Optimal selection of these
parameters is inherently application-specific, necessitating a multi-objective optimization
that balances converter efficiency, cost, thermal management, and operational
reliability for various use cases. For instance, energy storage applications require high
efficiency at low power ranges, where converters predominantly operate, whereas photovoltaic
(PV) systems demand optimization of the California Energy Commission
(CEC) efficiency to maximize energy extraction over a typical daily solar profile.
The methodology simultaneously tunes critical design variables, including dead
time, snubber capacitance, gate resistances, and gate drive voltages. Detailed loss
modeling is performed for both Silicon (Si) and Gallium Nitride (GaN) devices, incorporating
effects such as hard and soft switching transitions, reverse conduction,
gate drive losses, and magnetic core losses. Unlike traditional approaches that focus
solely on minimizing conduction and switching losses, the proposed framework employs
a multi-objective optimization strategy targeting single-point efficiency more
suitable for energy storage applications or, California Energy Commission (CEC)
weighted efficiency suitable for PV applications, and overall cost of implementation.
Thermal constraints are rigorously enforced through an iterative thermal modeling
loop integrated into the loss calculation process.\nThe framework is validated through extensive simulation and experimental results
at multiple power levels, including 1 kW, 4 kW, and across the CEC load
profile. The results demonstrate that dynamic dead-time adjustment and coordinated
snubber-gate parameter optimization significantly enhance overall efficiency
and reduce switching losses. The optimized converter achieves a peak efficiency of
98.88% at 4 kW and sustains high performance across the entire load range, making
it well-suited for applications such as electric vehicle chargers and energy storage
systems. An alternative optimization targeting cost yields a converter with slightly
reduced efficiency (98.01%) but significantly lower component and implementation
costs, offering a viable trade-off for cost-sensitive applications
Poverty Policy: Historic Institutional Approaches to Poor Relief in Canada
No full textIn Canada, social assistance programs act as a ‘safety net’ to prevent those living in poverty from reaching destitution. However, this safety net comes with expectations – in the form of welfare-to-work programs that mandate beneficiaries’ participation in work-related activities. Underlying these welfare-to-work programs are ideas surrounding citizenship, activation, dependency, and the role of the state in supporting the welfare of its citizens. Embedded in these programs are the ideas of market citizenship and activation, two ideas that tell the story of the ideal citizen in Canada: a self-sufficient and appropriately activated market citizen, who fulfils their obligation of supporting themselves through participation in paid employment. Subsequently, through the ideas of market citizenship and activation, social assistance beneficiaries represent the antagonist to the ideal citizen: an unmotivated, dependent, support-needing citizen. Although scholars often situate the emergence of the ideas of market citizenship and activation during the late 20th century period of welfare reform in Canada, this perspective negates the history of these ideas in social assistance policies. Informed by the theory of Critical Human Ecology and the methodology of Ideational Analysis, this thesis explores the development of the ideas of market citizenship and activation across institutional approaches to poor relief in Canada. By taking a long-term historical perspective, this thesis finds evidence of the ideas of market citizenship and activation as early as the 17th century in Canadian institutional approaches to poor relief, and counters the prevailing perspective that market citizenship and activation emerged in the late 20th century in Canadian institutional approaches to poor relief
Parametric Design Program: Enhancing Architects’ Early-Stage Design Decision-making
No full textUniversity students including both undergraduates and graduates face numerous challenges in their living environments, particularly in university-provided dormitories or off-campus rental accommodations. These residential spaces are frequently constrained by limited size, poor lighting conditions, and inefficient furniture layouts, creating ongoing design challenges for architects and developers. One of the most critical tasks in designing student housing is to establish spatial layouts that are both efficient and supportive of living and learning.
To respond to that challenge, this study develops and presents a user-centered parametric design program. Rather than provide predetermined solutions, it assists architectural judgment through rapid generating, testing, and refining of usable and desirable preliminary interior spatial layouts and furniture arrangement concepts at the conceptual stage, increasing the likelihood of discovering design solutions that can enhance students' living experiences. The parametric design program presented in this study was developed within the Grasshopper visual programming environment, combining spatial relationships, spatial functions, and users’ preferences into a flexible and iterative framework. This study demonstrates that parametric design can support designers in exploring more potential design options and assist them in identifying optimized design solutions. Methodologically, the study combines primary research—including informal interviews and questionnaire surveys with students (end users) and architects (primary users)—with secondary research into parametric design literature, as well as the technical development of the parametric design program within the Grasshopper platform. The study does not focus on Grasshopper programming or detailed software development. It emphasizes the potential impact of parametric design on optimizing early stage design workflows and accelerate preliminary design concept iteration.
This study contributes to broader discussions on the approach of transforming user needs into parameters and rules, and linking them into a parametric design system that enables designers to quickly iterate on design concepts responding to users’ requirements across architecture, industrial design, and other design fields
Association Between Parental Practices and Preschool-Aged Children's Physical Activity and Screen Time
No full textBackground: A healthy balance of regular physical activity and minimal screen time in the preschool years (3-5 years) is important for optimal development. Parents play an integral role in shaping children’s health behaviours. Understanding key parental practices that shape physical activity and screen time behaviours can inform interventions to support families and children’s healthy development. This thesis consists of two manuscripts. The objective of manuscript 1 was to examine the associations of parental-reported and device-based parental physical activity modelling and parent-child co-participation in physical activity with preschool-aged children’s physical activity. The objective of manuscript 2 was to examine the associations of parental-reported screen time modelling, restriction, and discussion with preschool-aged children’s screen time.
Methods: For manuscript 1, a cross-sectional sample of 122 parents with preschool-aged children (3-5 years) from the baseline time-point of the PLAYshop randomized controlled trial was utilized. Parental physical activity modelling was measured with accelerometers (parental light-intensity physical activity [LPA], moderate- to vigorous-intensity physical activity [MVPA], total physical activity [TPA]; 10 min/day) and via a parental-report questionnaire. Parent-child co-participation was measured with accelerometers using a Bluetooth proximity feature that can identify minutes of physical activity that parents and children were in close proximity (co-MVPA, co-TPA; 10 min/day) and via a parental questionnaire. Multiple linear regression models were conducted adjusting for covariates, including children’s age, sex, race/ethnicity, hours in childcare, and parental education. For manuscript 2, a cross-sectional sample of 350 parents with preschool children (3, 3.5, 4 years) from the baseline time-point of the longitudinal TECH project was utilized. Parental screen time practices, including modelling (parental screen time as a proxy), restriction (5 items; α=0.90; e.g., set specific viewing hours), and discussion (5 items; α=0.62; e.g., explain what something on the screen means) were measured via a parental-report questionnaire. Preschool-children’s screen time (TV/video viewing, video/computer games, and total screen time), across multiple devices, was also measured via a parental-report questionnaire. Multiple linear and logistic regression models were conducted that adjusted for demographic covariates, including children’s age, sex, race/ethnicity, number of siblings, hours in childcare as well as parental education and stress. Results: In regards to manuscript 1, device-based parental MVPA modelling was significantly associated with each children’s physical activity outcome (B=3.42-7.51). Device-based parental LPA and TPA were also significantly associated with children’s LPA (B=1.25-1.29) and TPA (B=1.86-1.91). Parent-child co-TPA was significantly associated with each children’s physical activity outcomes (B=1.77-4.27). Parent-child co-MVPA was also significantly associated with children’s MVPA (B=32.73; 95%CI:12.76-52.71) and TPA (B=50.44; 95%CI:13.08-87.80). No significant associations were found between parental-reported modelling and co-participation and children’s physical activity. Regarding manuscript 2, higher frequency of parental screen time restriction (possible range 1-4) was associated with significantly lower min/day of preschool children’s TV/video viewing (B=
-11.68; 95%CI: -21.63, -1.73) and total screen time (B=-12.96; 95%CI: -25.08, -0.83). Conversely, higher hr/day of parental screen time was significantly associated with higher min/day of preschool children’s TV/video viewing (B=5.82; 95%CI: 1.85, 9.80) and total screen time (B=7.77; 95%CI: 2.94, 12.61). Parental screen time discussion was not associated with preschool children’s screen time. Additionally, none of the parental practices were associated with higher odds of playing video/computer games.
Conclusions: This thesis addressed important gaps and limitations in the literature and findings help identify potential key targets for future family-based interventions aiming to support healthy physical activity and screen time behaviours in the preschool years. Specifically, given the strength of association observed for co-MVPA and children’s MVPA, this may be an important parental practice to target in future interventions. Findings also suggest parental screen time modelling and discussion may be important targets for future interventions aiming to minimize screen time in the preschool years. Future research with more rigorous study designs that recruit samples with more socioeconomic diversity are needed to build on this work
Deciphering Ahsa1: A Biochemical and Proteome-Wide Analysis of Its Role in Chaperone Regulation
No full textHsp90 is an essential molecular chaperone that plays a key role in maintaining protein homeostasis by assisting the folding, activation, and maturation of diverse client proteins. Hsp90 functions through a dynamic conformational cycle that is coupled to ATP hydrolysis. Its ATP driven conformational cycle is finely regulated by post translational modifications and a network of co chaperones. Among these regulators, Accelerator of Hsp90 ATPase 1 (Ahsa1) is the most potent stimulator of Hsp90 ATPase activity, yet its mechanistic role in metazoans, and its potential Hsp90 independent functions, remain incompletely understood. This thesis dissects the biochemical and cellular functions of a conserved 20-residue N-terminal segment of Ahsa1, termed the intrinsic chaperone domain (ICD), and evaluates Ahsa1-dependent proteome turnover. Quantitative ATPase assays, structure guided mutagenesis, and cell based co immunoprecipitation revealed that removing the ICD accelerates Hsp90 ATPase activity in vitro and impairs stable Ahsa1–Hsp90 recruitment in cells. Surprisingly, this region has also recently been shown to contribute to an Hsp90-independent chaperone role. The work here also demonstrates that the NxNNWHW motif is also essential in the mammalian protein function, revealing key differences and similarities in yeast and metazoan protein. To probe cellular roles of Ahsa1, a novel proteome wide bioorthogonal non-canonical amino acid tagging (BONCAT) pulse chase workflow was performed to measure in cell protein degradation kinetics. BONCAT profiling showed that Ahsa1 knock down modestly destabilises a select set of proteins, whereas over expression, especially of the ICD deleted variant, reshapes the half lives of hundreds of proteins, including factors beyond the canonical Hsp90 client repertoire. These data, coupled with in vitro holdase assays, support dual Hsp90 dependent and autonomous activities for Ahsa1. The study has also uncovered previously unappreciated roles for Ahsa1 in signalling and innate immune pathways. Together, these findings expand the current understanding of co-chaperone function by revealing new structural and functional roles for Ahsa1 in proteome maintenance. This work introduces BONCAT pulse chase proteomics as a powerful tool for studying chaperone mediated proteome dynamics and advancing understanding of co chaperone biology