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  • Ice Island and Iceberg Fluxes from Canadian High Arctic Sources

    Resource Type:
    Report
    Creator:
    Crawford, Anna, Copland, Luke, Mueller, Derek, and Van Wychen, Wesley
    Date Created:
    2023-02-22

  • The use of EEG and VR in Mental State Recognition

    Resource Type:
    Thesis
    Creator:
    El-Habrouk, Jaser
    Abstract:
    Mental state recognition (MSR) is important to multiple health-related fields. A virtual reality (VR) headset is used to induce mental states through both distractors and stressors. Participants solved arithmetic questions in VR, then outside of VR using a Muse S EEG device. A heart monitor was used throughout. Three research contributions followed: First, heart rate variability (HRV) data were compared between VR and non-VR sessions and correlated with established Test of Variables of Attention (T.O.V.A.) measurements used to asses participants' attention and focus. Second, a classifier was developed to differentiate between clean and noisy EEG data, with 92% accuracy. Lastly, linear regression models were developed, achieving mean squared error scores of 0.65 and 0.63 for 3-level stress and attention prediction from EEG data, respectively. In summary, this thesis explores the use of VR to induce mental states and advances the state of the art in EEG-based MSR.
    Thesis Degree:
    Master of Applied Science (M.App.Sc.)
    Thesis Degree Discipline:
    Engineering, Biomedical
    Date Created:
    2023

  • Anisotropy and Non-coaxial Behaviour of Sand Along Different Strain Paths

    Resource Type:
    Thesis
    Creator:
    Selvarajah, Premnath
    Abstract:
    Anisotropic characteristics of granular soil, consolidated to various initial stress states, were evaluated under generalized strain paths using hollow cylinder torsional shear tests. Fraser River sand samples prepared by water pluviation were subjected to isotropic and anisotropic consolidation stresses and sheared under undrained con- ditions along specific strain paths characterized by constant intermediate principal strain parameter (π‘πœ€) and various fixed principal strain directions (π›Όπœ€). A series of tests along different inclinations of the major principal strain with respect to the vertical depositional direction permitted an assessment of the interaction between principal strain directions and fabric. A decrease in strain hardening tendency is ob- served as the major principal strain aligned towards the bedding plane. Considering different levels of anisotropic consolidation stresses also allowed a detailed examina- tion of how initial static shear affects the responses. In particular, generated principal stresses and their direction, as well as the pore pressure responses, were closely exam- ined. Novel findings, that highlight range of intermediate principal stress parameter (π‘πœŽ) associated with the undrained plane strain condition, and the interaction be- tween π‘πœŽ and π‘πœ€ during shearing are presented. It was found that π‘πœŽ systematically decreases with shear strain in constant π‘πœ€ tests. The π‘πœŽ value in plane strain tests (π‘πœ€=0.5) was found to be in the range of 0.2 to 0.4 depending on the loading path, and the stage of shearing. The relationship between principal stress directions and plastic-strain increment directions was assessed to identify the nature of plasticity in the material. In order to ensure confident assessment of non-coaxiality, total strain was decomposed into elas- tic and plastic strain. The existence of non-coaxiality in Fraser River sand (FRS) was observed when the sand was subjected to undrained shear at fixed principal strain di- rections that do not coincide with the fabric axis of symmetry. Non-coaxiality was not observed when the principal directions of stress/strain coincided with the fabric axis of symmetry. It was also noticed that irrespective of the initial condition, the degree of non-coaxiality reduces with increasing shear strain. The influence of initial fabric and principal strain direction on the degree of non-coaxiality was analyzed in detail. Test results show that irrespective of initial condition, the degree of non-coaxiality reduces as the principal strain direction aligns towards the bedding plane direction. The degree of non-coaxiality in FRS at the phase transformation (PT) state and the effect of intermediate principal stress on non-coaxiality were also examined. Different values of degree of non-coaxiality at PT state indicate that the phase transformation state can not be thought of as a good representation of the critical state even though the friction angle at phase transformation has been found to be similar to that at the critical state. The results revealed that the non-coaxial behaviour of soil is also influenced by the intermediate principal stress parameter (which could alternatively be represented by the Lode angle). The influence of non-coaxiality on stress-dilatancy of sand was investigated under generalized loading conditions, and it was found that the effect of non-coaxiality on stress-dilatancy characteristics of the sand was influenced by its initial fabric anisotropy. The effect of non-coaxiality in stress-dilatancy relationship has been investigated within the theoretical framework developed by Gutierrez and Ishihara (Gutierrez and Ishihara, 2000, Soils Found., 40(2):49–59) and Gutierrez and Wang (Gutierrez and Wang, 2009, Granul. Matter, 11(2):129–137) who extended the Rowe’s stress-dilatancy relation to the non-coaxial conditions. Our research study verifies this framework beyond its original context of 2D simple shear tests.
    Thesis Degree:
    Doctor of Philosophy (Ph.D.)
    Thesis Degree Discipline:
    Engineering, Civil
    Date Created:
    2023

  • Differential Introgression Between the Northern and Southern Extents of the Lodgepole x Jack Pine Hybrid Zone Suggests Environmentally-driven Selection and Local Adaptation.

    Resource Type:
    Thesis
    Creator:
    Yaremchuk, Danya Daria
    Abstract:
    Lodgepole and jack pine form a mosaic hybrid zone in western Canada. Introgression occurs between lodgepole and jack pine through this hybrid zone by repeated backcrossing with advanced generation hybrid progeny. Using environmentally-associated SNPs identified by redundancy analyses, we examined patterns of introgression between the northern and southern extents of this hybrid zone to identify differential introgression. Through genomic cline analyses, we found extensive introgression of these SNPs through the hybrid zone. Twenty-eight SNPs had significantly different patterns of introgression between the northern and southern extents. Fine-scale patterns revealed several SNPs that were introgressing more frequently than expected, suggesting adaptive introgression. We found that adaptive introgression is occurring more frequently in the northern hybrid extent compared to the southern hybrid extent, suggesting different environmental pressures. Using gene annotations and major allele frequency maps, we identified evidence of differing environmental pressures resulting in putative local adaptation within this hybrid zone.
    Thesis Degree:
    Master of Science (M.Sc.)
    Thesis Degree Discipline:
    Biology
    Date Created:
    2023

  • Toward a "Just, Peaceful and Safe Society:" How Risk Factors and Criminogenic Needs Align with Parole Decisions

    Resource Type:
    Thesis
    Creator:
    Mularczyk, Kimberly Patrycia
    Abstract:
    Board members (BMs), as gatekeepers between continued imprisonment and freedom, decide upon the potential release of incarcerated individuals considered for parole in Canada. Although a focal concern of BMs is community protection, annual Canadian government reports do not contain information on parole populations' criminogenic needs. Literature provides little insight into what factors might relate to parole decisions. In addition, prior research has not compared the risk profiles and release decisions of those who applied for day parole (DP) or full parole (FP) exclusively to those who applied simultaneously. The current dissertation addresses these gaps in two studies using an archival sample of federally sentenced individuals (N = 3,613). The sample includes conditional release and detention decisions made by the Parole Board of Canada between 2010 and 2017 (age at decision: M = 39 years old, SD = 12.80). Study 1 showed that risk/need scores and some institutional (e.g., CSC recommendation) and parole factors (e.g., decision type) predicted conditional release. CSC recommendations predicted release probability for DP (Adjusted Odds Ratio [AOR] = 35.33), FP (AOR = 18.83), and SR (men at a detention review; AOR = 43.94). Moreover, Study 1 found that among those who reoffended on FP (10-32% at one and two-year fixed follow-up) or men who reoffended on statutory release after a detention review (44-80%; at one and two-year fixed follow-up), most revocations (72-75%) first occurred for breaches as opposed to new crimes. Study 2 showed that BMs often imposed special conditions concerning alcohol, avoiding certain persons, drugs, reporting and disclosures, and treatment. Study 2 also found that after accounting for risk/need, the number of special conditions imposed on FP did not predict revocations for any breaches or crimes on FP at one-year (AOR = 1.11) or two-year (AOR = 0.82) fixed follow-up. Future research is required to untangle the potential overlapping variance that unmeasured variables (e.g., prior conditional release successes or revocations) may share with CSC recommendations. Overall, findings support the assertion that BMs use risk/need information to inform decisions and that the number of special conditions imposed does not influence revocation rates after accounting for risk/need.
    Thesis Degree:
    Doctor of Philosophy (Ph.D.)
    Thesis Degree Discipline:
    Psychology
    Date Created:
    2023

  • Role of TrkB.T1 in Glial Inflammatory Response Elicited by MHV

    Resource Type:
    Thesis
    Creator:
    Heiratifar, Noora Donna
    Abstract:
    In the present thesis, we used a rodent analogous coronavirus, murine hepatitis virus (MHV), in culture to directly assess its impact on astrocytic and microglial cells. Given the increasing importance of the brain neurotrophic factor (BDNF)-TrkB signaling system in glial functioning, we also assessed whether the unique TrkB.T1 truncated isoform (the only BDNF receptor on astrocytes) would modulate glial reactivity to MHV viral infection. Our results largely support the notion that MHV readily infects astrocytes and caused a degree of toxicity of these cells. The addition of microglia to the astrocytic culture modulated the magnitude of this effect and greatly increased pro-inflammatory cytokine release. Furthermore, TrkB.T1 deficiency appeared to greatly reduce astrocyte viability and microglial morphology. These data may have useful implications for better understanding the nature of glial responses to coronaviral infection and the importance of TrkB in such responses.
    Thesis Degree:
    Master of Science (M.Sc.)
    Thesis Degree Discipline:
    Neuroscience
    Date Created:
    2023

  • Towards a critique of state secrecy: Uncovering the rhetorical practices of secret keepers and their legitimization by the discourse of law

    Resource Type:
    Thesis
    Creator:
    Lefebvre, Stephane
    Abstract:
    This thesis examines the rhetorical devices that secret keepers in Canada, the United Kingdom and the United States use to justify the non-disclosure of state secrets. It also examines the manner in which judges in these three countries write and speak about state secrets. By embracing the rhetorical devices used by secret keepers and materializing them in reported decisions, judges add legitimacy to the discourse of secret keepers and directly assist in its reproduction and distribution. Taken together, the discourse of the state and the discourse of law on state secrecy sets up the dominant interpretive frames with which any public engagement, whether supportive or critical, must engage. While the persuasive social effect and perceived legitimacy of this combined discourse may ebb and flow, it appears enduring and difficult to challenge despite the existence of counter-discourses and concessions such as the adoption of access to information legislation. This thesis seeks to understand how state secrecy discourse becomes or appears preeminent, and how it reproduces itself, as a first step in formulating a fuller critique of this discourse.
    Thesis Degree:
    Doctor of Philosophy (Ph.D.)
    Thesis Degree Discipline:
    Legal Studies
    Date Created:
    2023

  • Modular Verification of Hierarchical Component-Based Software Systems

    Resource Type:
    Thesis
    Creator:
    Baak, James Alec William
    Abstract:
    Using Component-based Software Engineering approaches with Formal Methods has seen an influx of interest in the recent decades. The joining of these two disciplines have been stifled though due to unclear component specifications and expensive formal verification techniques, which hurt the reusability and scalability of complex software systems. In this work, we expand on current component-port-connector metamodels for formally specifying a system's architectural and behavioural requirements into a hierarchical component system structure by using abstract Composite Components. The Composite Components of a system model can then utilize modular verification for isolating the verification process into modules surrounding Composite Components and generating higher level properties. We formalize our metamodel in Alloy 6 and present a template for specifying system properties for modular verification which enables the reuse of previous verification efforts on satisfied modules. We conclude with an example case study system and analysis of the modular verification strategy.
    Thesis Degree:
    Master of Applied Science (M.App.Sc.)
    Thesis Degree Discipline:
    Engineering, Electrical and Computer
    Date Created:
    2023

  • A NUMERICAL STUDY OF THE IMPACT OF MAKE-UP AIR VELOCITY ON THE SMOKE CONDITIONS IN AN ATRIUM

    Resource Type:
    Thesis
    Creator:
    Boakyewah, Barbara
    Abstract:
    This research numerically investigates the effect of make-up air on the smoke conditions in an atrium under different make-up air velocities and fire sizes. A total of twenty-four (24) simulations were conducted using the Fire Dynamics Simulator (FDS) to consider different scenarios of fire located at the center (axisymmetric), northwest corner and southeast corner of the atrium. Fire sizes of 1 MW, 3 MW and 5 MW along with different make-up air velocities of 1 m/s, 1.5 m/s, 2.5 m/s and 3.5 m/s were simulated to investigate their effect on smoke conditions the atrium. The results showed that the simulation predicted slightly higher temperatures and lower smoke layer heights when compared to the experimental tests. The position of the fire source at different locations showed different and increasing temperatures when the velocity changes from 1 m/s to 3.5 m/s, however the effects of make-up air velocities were minor.
    Thesis Degree:
    Master of Applied Science (M.App.Sc.)
    Thesis Degree Discipline:
    Engineering, Civil
    Date Created:
    2023

  • A Web Based Architecture to Operationalize Geospatial Simulation Environments

    Resource Type:
    Thesis
    Creator:
    St-Aubin, Bruno
    Abstract:
    Simulation is inherently multi-disciplinary. It requires knowledge about the system under study, expertise in simulation theory to define models and programming skills to implement models. Geospatial simulation requires an additional layer of expertise in topology, geospatial data structures, spatial analysis, computational geometry, and other related topics. Commercial modeling and simulation software can be used to provide an environment to facilitate simulation studies for users. However, these software tend to be narrowly scoped to specific business applications and tightly couple model and simulator. As such, it is difficult to expand their usage and reuse them outside of the application domain they were intended for. The Discrete Event System Specification (DEVS) is a modular and hierarchical simulation formalism that clearly separates the model, simulator and experiments. It can be used break down the disciplinary silos within which single-use simulators are built and allow users to study real-world systems from a broad range of application domains. In this research, we present an architecture that facilitates the operationalization of DEVS based, geospatial simulation environments in multidisciplinary projects. The architecture relies on a clear definition of roles and responsibilities to leverage the different skillsets in an organization. It considers a series of business processes for modelers, subject matter experts, web developers and end users. It relies on a web-based architecture to provide simulation as a service capability and support users across the entire simulation lifecycle. It seeks to democratize DEVS simulation by making use of the strengths and skills available in larger organizations and by providing the necessary tools for collaboration. Importantly, it preserves key features of DEVS (genericity, modularity, flexibility, etc.) and encourages users to follow best practices in model documentation to foster model reusability and improve model discoverability. It relies on modeling and simulation as a service to overcome technological barriers of entry for DEVS simulation and provide a set of reusable tools to design simulation-based, web applications for end users.
    Thesis Degree:
    Doctor of Philosophy (Ph.D.)
    Thesis Degree Discipline:
    Engineering, Electrical and Computer
    Date Created:
    2023