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Data-driven Surrogate Models for Wind Turbine Design and Maintenance Applications
No full textThere is a gap between the current contribution of wind energy to the global electricity generation mix and its potential capacity. This discrepancy underscores the necessity for addressing social, economic, and technical hurdles that are impeding the broader integration and acceptance of wind energy. The research focuses on tackling the modelling challenges in wind energy by employing Surrogate Model (SM) techniques, combining probabilistic methods, machine learning, and simulation technologies.
This dissertation aims to develop SMs capable of mapping wind time series to the power output as well as extreme and fatigue loads on wind turbines. In this dissertation, I try to answer a number of crucial questions: determining the most effective type of SM for this mapping, identifying the optimal sampling method for building these SMs, extending the applicability of the developed SMs with minimal effort, and leveraging publicly available simulation tools and wind turbine models for turbine health assessment. These objectives are essential for improving wind turbine design, operation, and maintenance, enhancing their efficiency and reliability.
Throughout the dissertation, there is an effort to bridge the gap between theoretical research and practical application. The surrogate models developed are presented as a contribution to the integration of theoretical concepts with practical applications in the field of wind turbine design and maintenance. Central to this research is the development of SMs for effectively mapping wind time series to the extreme and fatigue loads experienced by wind turbines. The aim is to find the optimal SM type that balances accuracy with computational feasibility. As the wind turbine faces diverse conditions, I propose adaptable methodologies to optimize the SM performance across various settings. Additionally, I investigate the potential of combining publicly available wind turbine models with probabilistic data-driven models to assess turbine health.
First, a non-intrusive Polynomial Chaos Expansion (PCE) is constructed based on the outputs from the NREL 5MW Blade Element Momentum (BEM) model, demonstrating the convergence of sectional statistics in the results. Subsequently, I utilize the SM to estimate thrust and torque on the rotor and perform a sensitivity analysis of the extreme loads to the number of Monte Carlo Simulations (MCS) in the SM. Transitioning from the PCE realm, I adopt a sequential Machine Learning (ML) method to map wind time series to the Damage Equivalent Load (DEL) of wind turbine loads. I demonstrate that the developed SM, based on a Temporal Convolutional Network (TCN)-Fully Connected Neural Network (FCNN) architecture, is capable of capturing the wind turbine structural dynamics. It demonstrates adaptability in digesting the upstream wakes and accurately estimating the DEL utilizing Transfer Learning (TL). Moving beyond purely synthetic data, I propose the development of a probabilistic data-driven model, integrating limited wind turbine measurements with synthetic data for wind turbine health assessment purposes. I illustrate that an Approximate Gaussian Process Regression (AGPR) trained on a year’s worth of Supervisory Control and Data Acquisition (SCADA) data, combined with simulation outputs from a publicly available wind turbine model, emerges as a promising probabilistic tool for wind turbine health assessment.Graduat
Expanding democratic employee ownership in Canada: Policy options
Get PDFThis report examines policy options to expand democratic employee ownership of businesses in Canada. Whether taking the form of worker cooperatives, employee ownership trusts, or employee stock ownership plans, employee-owned firms have enjoyed considerable successes in jurisdictions like Italy, Spain, the United States, France, and the United Kingdom. But they remain relatively rare in Canada, despite the fact that they tend to be at least as productive as conventional investor-owned firms and have significant benefits for workers, firms, and society.Simon Pek would like to acknowledge financial support through his appointments as a Social Capital Partners Fellow at the Institute for the Study of Employee Ownership and Profit Sharing and as a University of Victoria President’s Chair.FacultyUnreviewe
Male fitness and the persistence of a selfish X chromosome in Drosophila testacea
Get PDFSelfish X chromosomes bias their own transmission during reproduction by interfering with Y-bearing sperm, a phenomenon best characterized in flies. Male flies carrying a selfish X chromosome produce almost exclusively female offspring, with potentially negative fitness consequences. Left unchecked, selfish X chromosomes may spread to fixation and result in extinction; therefore, one major question in the field is to understand how these chromosomes persist in nature. My research investigated one of two main hypotheses for selfish X persistence: the potential fitness consequences of harbouring the selfish element. The Palearctic woodland fly, Drosophila testacea, was recently found to carry an ancient selfish X chromosome, which serves as a great model for understanding how selfish X chromosomes persist over evolutionary time. My research investigated the contribution of male fitness effects in the persistence of this selfish X chromosome. I asked (1) if male age affects drive strength; (2) if males that carry a selfish X chromosome have reduced survival; (3) if female flies preferentially mate with wildtype or driver males; (4) if female mate choice interacts with male age; (5) if male mate success is affected by drive presence; and (6) if female propensity to remate is affected by male genotype. I found that male age does not alter strength of drive, driver males do not suffer reduced survival compared to wildtype males, females do not exhibit mate discrimination against driver males, and male mate success and female propensity to remate are not affected by male genotype. The present study suggests that while some male fitness effects play a role in drive persistence in D. testacea, male age, longevity, and mate success do not. Selfish X chromosomes are increasingly recognized as major players in organismal biology. Research on meiotic drive systems such as the selfish X chromosome in D. testacea will deepen our understanding of how gene drive persists over evolutionary time, and may provide insight on the prospect of synthetic gene drives.Graduate2025-05-0
Examining the Feasibility of Sentinel-1 InSAR data for landslide monitoring and failure forecasting in western Canada.
Get PDFLandslides are geological hazards that significantly threaten human life, infrastructure, and biotic
habitat in areas with steep slopes. Precursory signs of a landslide can be undetectable or non-
existent, making the evacuation of residents unlikely. The ongoing climatic cycles and geological
triggers imposed on regions susceptible to landslides exhibit long-term ground movement
superimposed with accelerations due to seismicity or precipitation. Landslide monitoring and
forecasting aims to understand the structural dynamics of the slide accelerations to estimate
when there will be a catastrophic failure. The thesis explores the potential of InSAR technology
for monitoring slope movement in the western Canadian Cordillera. The study takes a two-
pronged approach: first, investigating the capability of the technique to detect movement on
slopes that have already undergone previous landslide activity, focussing on the Garibaldi
Volcanic Complex (GVC) as a case study, and second, analyzing five sites that have recently
experienced landslides to determine if InSAR technology could have forecasted the failures.
The InSAR results presented in the thesis show that ground displacement occurred on the slopes
of all the study sites, which corresponded with previous landslide activity. However, InSAR
results collected during winter months were less detailed and frequent than those collected using
a seasonal approach. The forecasting study discovered that all the sites displayed signs of
preceding movement on the slopes, which were successfully detected by InSAR. Furthermore,
each site encountered extreme weather conditions, resulting in catastrophic failure. The Elliot
Lake and Ecstall River sites experienced seismic activity the same afternoon as the landslide
events, potentially connected to glacial loss and retreat. Results obtained during snowfall were
less reliable than the summer acquisitions.
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The results from the thesis demonstrate that the Sentinel-1 mission's temporal resolution is
inadequate for creating a real-time monitoring system for landslide-prone slopes in western
Canada. Factors that trigger landslide acceleration, such as precipitation, seismicity, and
geological processes, can occur over decades or hours. Hence, the primary role of Sentinel-1 in
landslide monitoring is identifying large-scale moving slopes. Future InSAR platforms could
provide a promising solution with high temporal resolution, making landslide forecasting and
monitoring a reality.Graduat
Substance use among transgender and non-binary people in Canada
No full textBackground
Substance use is a public health concern. There is a paucity of population research comparing substance use between transgender and non-binary (TGNB) people and the general population and examining substance use correlates among TGNB sex/gender groups. My dissertation aims to 1) estimate and compare substance use prevalence among TGNB people and the general population in Canada; 2) examine correlates of hazardous alcohol drinking among TGNB people in Canada; and 3) examine how cigarette and e-cigarette use changed between pre-COVID-19 and after the first six months of the COVID-19 pandemic and examine the effects of COVID-19 impacts on changes in cigarette and e-cigarette use among TGNB people in Canada.
Methods
To meet the first aim (manuscript 1), I estimated and compared substance use prevalence (using standardized prevalence differences) among 2,294 TGNB people (from Trans PULSE Canada survey - TPC) and the general population in Canada from two national population-based surveys, the 2017 Canadian Tobacco, Alcohol, and Drugs Survey (CTADS) and the 2017-2018 Canadian Community Health Survey (CCHS).
For my second aim (manuscript 2), I employed minority stress theory to examine potential predictors of hazardous alcohol drinking (HAD) among 2,324 TGNB individuals from the TPC. Logistic regression models were fit to examine the effects of 1) minority stressors and discrimination and 2) stress-buffering factors on the likelihood of HAD, stratified by gender.
For my third aim (manuscript 3), within-person changes in cigarette and e-cigarette use between the two time points among 767 TGNB individuals who participated in the TPC (baseline) and the Trans PULSE Canada Cohort COVID survey (follow-up) were calculated. Multinomial logistic regression models were fit to examine mental health, social support, and pandemic-related predictors of changes (compared with no change) in cigarette and e-cigarette use.
Results
I found that TGNB people used fewer cigarettes and alcohol, but more e-cigarettes, cannabis, and unregulated drugs than the general population in Canada.
Enacted discrimination predicted higher odds of HAD in all four TGNB sex/gender groups. Social support was associated with lower odds of HAD in trans men, non-binary assigned female at birth (NB-AFAB), and non-binary assigned male at birth (NB-AMAB) groups, but with higher odds of HAD in trans women. Mixed effects of gender distress, gender positivity, and gender-affirming medical care were also reported across sex/gender groups.
More participants reduced (6.1%) than increased (3.3%) their cigarette use. Approximately equal numbers of participants increased (4.8%) and decreased (4.1%) their e-cigarette use. Increased e-cigarette use (compared with no change) was associated with working more during COVID-19 and a negative impact of COVID-19 on one’s financial security. Greater depression at baseline was associated with higher odds of reduced cigarette use. Higher social support was associated with lower odds of increased cigarette use.
Conclusions
My dissertation provides an understanding of different aspects of substance use among TGNB people in Canada, including robust population-level evidence on substance use disparities between TGNB groups and general population, understanding about predictors of past-year HAD within and across the TGNB population, and change in cigarette/e-cigarette use and predictors of such change following onset of the COVID-19 pandemic. Substance use patterns also differed by TGNB sex/gender groups, calling for tailored public health strategies to substance by TGNB groups. My dissertation findings also suggest that harms of substance use could be mitigated through public health policy and interventions that consider reducing structural discrimination, strengthening social support, ensuring financial security, and addressing mental health problems, tailored for distinct TGNB sex/gender groups.Graduat
Community-engaged care for rare, threatened and endangered species in an urban nature park
No full text• Supporting the basic psychological needs of autonomy (i.e., feeling volitional), competence (i.e., feeling skillful) and relatedness (i.e., feeling socially connected) in context of promoting environmentally sustainable actions can help increase motivation to perform such actions.
• Need fulfillment can be facilitated through provision of a need-supportive environment/conditions (e.g., providing explanations for why someone would want to engage in a behavior can support autonomy; toleration of failure can support competence; teamwork can support relatedness).
• Feeling connected to nature is a crucial first step to caring more about the welfare of the environment, and thus can lead to greater engagement in PEBs. Nature connectedness can be facilitated through nature exposure, participating in stewardship (and other PEBs), and practicing mindfulness.
• We must change the way we think so that we may be better able to address challenges, including better serving equity-deserving groups. Some of the ways this could be done is through thinking outside the box, shifting perspectives and worldviews, and the use of pro-environmental communication.
• It is necessary to decolonize our thinking. One way this could be done is through Two-Eyed Seeing, which considers the strengths of Indigenous and Western ways of knowing equally in order to determine best solutions in order to sustain the Earth. This method can also help facilitate more meaningful engagement in collaborative settings.
• Partnering and outreach with organizations that serve equity-deserving groups as well as Indigenous Knowledge Keepers can help reduce barriers to nature accessibility. Building respectful and trustworthy relationships with equity-deserving groups is essential.
• In communicating with someone who does not or cannot be convinced to care about the environment, communication strategies such as message framing may be more effective, as they can be used to appeal to a person’s existing values and attitudes. Message framing works best when they communicate support for basic psychological needs and intrinsic goals. To find out these attitudes, it can be helpful to approach a person with acceptance, openness, and curiosity rather than judgement.Swan Lake Christmas Hill Nature SanctuaryGraduat
An Intersectional Analysis of Client Satisfaction with Home Care in Canada
No full textHome care is a priority for all Canadians but evidence from literature suggests that the home care system is generally prone to inequality. Client satisfaction is an integral component of home care, which measures the quality of home care. This study used the intersectional framework of gender and Indigenous identity to analyze client satisfaction with home care among home care recipients in Canada to determine the existence of inequalities in client satisfaction with home care.
The study design was based on secondary data analysis. The data source was the Canadian Community Health Survey 2021. The study population was respondents who received home care in the last 12 months. Intersectional strata (dummy variables) were created from gender and Indigenous identity. The outcome variable was client satisfaction (a binary variable with 0 “Not satisfied/Undecided” and 1 “Satisfied”). The control variables were age, income, sexual orientation, and language often spoken. Provincial/Territory variable was used for clustering the standard errors to account for heteroscedasticity across the clusters of observations. Quantitative analyses were conducted using frequencies, percentages, and multiple linear regression models. Statistical significance was set at p<0.05.
The non-Indigenous men and the non-Indigenous women together accounted for about 75 percent of the respondents, while the Indigenous men and the Indigenous women together accounted for about three percent of the respondents. Among the non-Indigenous men and the non-Indigenous women, 90.7 percent and 90.1 percent respectively expressed satisfaction with home care; meanwhile, 82.0 percent of Indigenous men and 88.8 percent of Indigenous women respectively expressed satisfaction with home care. Overall, 90.4 percent of the respondents were satisfied with home care. After controlling for age, income, sexual orientation, and languages, the regression analysis identified the Indigenous women and the non-Indigenous women as significantly (p<0.05) having a 9.6 percentage point and a 10.2 percentage point lower satisfaction with home care respectively, relative to “men with other identities”.
The study findings suggest the existence of inequalities in client satisfaction with home care, which is a barrier to the fundamental objectives of the program in Canada. The inequality in client satisfaction with home care identified in this study can be tackled in two ways. One approach involves community-based intervention, where experts lead strategy development and the community helps carry it out, gradually taking over responsibility. Alternatively, community development work emphasizes empowering community groups to identify and address disparities themselves, focusing on long-term sustainability and community empowerment. This approach prioritizes community involvement in resolving underlying issues.Graduat
Using living crystallization-driven self-assembly to form functional π-conjugated nanostructures for potential optoelectronic device applications
Get PDFAt the micro- and nanoscale, mimicking the level of complex organization observed in nature is difficult, and reproduction of these materials has been a key challenge in the fields of materials science and synthetic chemistry. Solution self-assembly of amphiphilic block copolymers (BCPs) is a promising route towards the construction of nanoscale assemblies with various sizes, morphologies, and material properties. Living crystallization-driven self-assembly (CDSA) of polymers with a crystallizable core-forming block has emerged as a valuable method to exert control over the dimensions of one- and two-dimensional (1D and 2D) nanostructures. This method reliably produces nanostructures with predictable sizes and low size distributions.
Due to the variety of BCPs capable of crystallization, a wide array of hierarchically organized nanostructures have been fabricated which show promising potential for application to a broad assortment of fields such as optoelectronics, biomedicine, and catalysis. The work presented in this thesis focuses on expanding the library of materials known to be compatible with living CDSA by introducing a new crystallizable π-conjugated core-forming block. This work also seeks to extend controlled self-assembly techniques in systems where precise nanoscale control is highly sought-after and deepen our understanding of the processes that govern π-conjugated block copolymer self-assembly by establishing structure-property relationships; the practical realization of which are all key goals in modern energy, materials, and nanoscience research.Graduate2025-06-1
A chemical characterization of the Endeavour non-buoyant plume, Juan de Fuca Ridge
Get PDFThis study aims to provide a quantitative chemical characterization of the Endeavour non-buoyant plume and examine the processes that impact trace metal transport from vent sites to the ocean interior. The chemistry of the Endeavour non-buoyant plume was analyzed using filtered and unfiltered seawater samples collected at 5 stations, starting on-axis at the Main Endeavour Vent field and extending ~45 km southwest of the axial valley. The spatial distribution of these trace metals is likely controlled by a number of processes, including metal sulfide precipitation, oxidation, sedimentation, and plume mixing.
Iron (Fe) and manganese (Mn) are limiting or co-limiting nutrients for primary productivity, nitrogen fixation and other biogeochemically important processes in the ocean. The transport of metals associated with hydrothermal plumes and the processes that impact their fate are poorly understood. High concentrations of dFe (24-68 nmol kg-1) and dMn (46-98 nmol kg-1), relative to ambient seawater concentrations at similar depths in the region, were observed proximal to the vent field, followed by a sharp decrease to 1.2-2.9 nmol kg-1 dFe and 0.76-1.4 nmol kg-1 dMn 45 km southwest of the axial valley. Roughly 66% of the Fe present in the non-buoyant plume proximal to the vent field is in the particulate phase (defined as the difference between total dissolvable and dissolved). The particulate phase decreases to ~45% at the most distal station. Particulate Mn increases with distance from the vent field with 25% proximal to the vent field and 56% 45 km off-axis. This study hypothesizes that the spatial distribution and size partitioning of Fe and Mn can be explained by a combination of sulfide precipitation near-field, oxidation and oxide formation, and plume mixing with surrounding seawater.
Chalcophile elements including cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), lead (Pb) and cadmium (Cd), are trace metals often associated with hydrothermal systems. Due to precipitation processes, these trace metals are not typically found in non-buoyant plumes far from vent fields. Correlations between these chalcophile elements with particulate Fe at END1 indicate similar removal pathways and highlight the importance near-field processes (precipitation, oxidation, mixing) play in controlling their net-input to the ocean. When compared to the geochemistry of sediments at the Main Endeavour Vent field, non-buoyant plume chemistry shows similar spatial trends. Furthermore, high mass accumulations of Fe, Zn and Cu on-axis along with the presence of chalcopyrite, pyrite, and sphalerite help explain the higher proportion of the particulate phase of these elements proximal to the vent field.Graduat
Evaluating the design of the first marine protected area network in Pacific Canada under a changing climate
No full textMarine protected area (MPAs) networks can buffermarine ecosystems from the impacts of climate change by allowing species to redistribute as conditions change and by reducing other stressors. There are, however, few examples where climate change has been considered in MPA network design. In this paper, we assess how climate change considerations were integrated into the design of a newly released MPA network in the Northern Shelf Bioregion in British Columbia, Canada, and then evaluate the resulting network against projected physical and biogeochemical changes and biological responses.We found that representation, replication, and size and spacing recommendations integrated into the design phase were met in most cases. Furthermore, despite varying degrees of projected changes in temperature, dissolved oxygen, and aragonite saturation across the MPA network, suitable habitat for demersal fish species is projected to remain in the network despite some redistribution among sites.We also found that mid-depthMPAs are particularly important for persistence, as fish are projected to move deeper to avoid warming in shallower areas. Our results highlight that a representative MPA network with adequate replication, that incorporates areas of varying climate change trajectory, should buffer against the impacts of climate change.FacultyReviewe