Faculty of Graduate Studies Online Theses
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Item Open Access Qualifying and Regulating the Use of Artificial Intelligence in Software Systems for the Canadian Nuclear Sector(2024-10-29) Dahaweer, Samer; Not Applicable; Master of Science; Department of Engineering Mathematics & Internetworking; Not Applicable; Dr. Kamal El-Sankary; Not Applicable; Dr. Farzaneh Naghibi; Dr. Issam HammadThis thesis examines the inadequacies in qualifying Artificial Intelligence (AI) software for the Canadian nuclear energy sector. The nuclear energy sector is a high-risk environment with strict regulations to ensure safety. Despite the rising popularity of new technologies like AI, a compliance assessment would be needed against nuclear qualification procedures. First, the thesis analyzes the existing regulatory framework within the Canadian nuclear sector. This analysis reveals potential gaps that traditional software qualification methods fail to address when applied to AI. The risks of AI, primarily linked to the complexity and opacity of decision-making processes, show the need for a new approach to AI regulation in nuclear. Next, a review of the Canadian regulatory framework focusing on the Canadian Standards Association (CSA) N290.14 with case studies of qualifying commercial software is presented to showcase the software qualification lifecycle. Through these detailed case studies, gaps are identified when applying the software qualifications methods to AI software. The thesis also suggests three methodologies for future AI qualification: model interpretability, feature importance, and data variety. These features are investigated in order to improve the transparency, reliability, and safety of AI applications in high-risk contexts such as nuclear power plants. Finally, the thesis proposes incorporating these three methodologies of AI into the software qualification framework to significantly mitigate the risks and support a safe deployment and operations of AI based software in the nuclear sector.Item Open Access Investigating in-season management strategies for triazine resistant common lambsquarters (Chenopodium album L.) In Atlantic Canadian potato production(2024-10-28) Anderson, Laura; Not Applicable; Master of Science; Department of Plant, Food and Environmental Sciences; Not Applicable; N/A; Not Applicable; Dr. Sameul Asiedu; Dr. Aaron Mills; Dr. Andrew McKenzie-Gopsill; Dr. Scott WhitePotato (Solanum tuberosum L.) producers in Canada’s Atlantic provinces of Prince Edward Island (PE) and New Brunswick (NB) rely on photosystem II (PSII)-inhibiting herbicides to provide season-long weed control. Despite this, a high proportion of common lambsquarters (Chenopodium album L.) populations have been identified as resistant to this class of herbicides. With the absence of new herbicide chemistries, weed science research has regained focus on preventative integrated weed management (IWM) strategies. As such, this project aims to investigate common lambsquarters biology and seedbank dynamics to optimize control tactics that increase mortality, deplete the weed seedbank, and decrease germination and viable seed shed. Crop-topping common lambsquarters post-flowering by mowing or wick-applied glyphosate reduced common lambsquarters harvest index and viable seed production. Soil-incorporation of fast-establishing cover crops reduced the common lambsquarters seedbank as well as populations in subsequent potato crop. Combined, this study demonstrates how alternative integrated weed management strategies can be utilized for seedbank management of herbicide-resistant common lambsquarters in potato production systems.Item Open Access ENHANCING THE COMPREHENSIBILITY OF MEDICAL PREDICTION MODELS WITH KNOWLEDGE GRAPHS: A NEURO-SYMBOLIC EXPLAINABLE AI APPROACH(2024-10-31) Rad, Jaber; Not Applicable; Doctor of Philosophy; Faculty of Computer Science; Not Applicable; Dr. Enea Parimbelli; Not Applicable; Dr. Samina Abidi; Dr. Hassan Sajjad; Dr. Syed Sibte Raza Abidi; Dr. Karthik TennankoreA challenge in using machine learning (ML) for decision support in critical domains such as healthcare is their lack of transparency in making predictions. eXplainable Artificial Intelligence (XAI) aims to explain the underlying decision logic and feature importance of black-box ML models, to build trust in the use of ML models. Despite advance XAI approaches, the comprehensibility of black-box ML model’s explanations remains a challenge. To enhance the comprehensibility of explanations, Neuro-Symbolic (NeSy) explainability approaches incorporate external knowledge sources to provide contextual information beyond just the use of input features in generating explanations. This thesis proposes a NeSy XAI framework to enhance the comprehensibility of explanations for ML models’ predictions in clinical settings, aiming to bridge the gap between human-comprehensible explanations and those provided by traditional XAI methods. Our approach integrates data-driven and knowledge-driven methodologies to offer conceptually-salient, domain context-rich explanations. The data-driven component of our framework employs model-agnostic surrogate modeling to generate an optimized set of transparent decision paths, based on the metrics of fidelity, coverage, confidence, and compactness, to represent the decision logic of black-box models. The knowledge-driven component of our framework integrates external domain knowledge to the decision paths in terms of a Semantic Explanation Knowledge Graph (SeE-KG) to generate semantically-rich context-sensitive and compressive explanations. We developed a graph-based visualization system that allows users to query the SeE-KG in near-natural language for localized, context-specific insights and to explore dataset-wide trends. The framework’s practical application is demonstrated in the complex task of organ allocation, specifically kidney transplantation. Using a comprehensive dataset of kidney transplants sourced from the Scientific Registry of Transplant Recipients (SRTR), the framework generates explanations for graft survival predictions, highlighting the underlying factors contributing to the outcomes (graft survival or failure) across donor-recipient combinations.Item Open Access ECOSYSTEM SERVICES TRADE-OFFS OF SALT MARSHES AS COASTAL NUTRIENT FILTERS VERSUS GREENHOUSE GAS SINKS(2024-10-28) Steele, Jacob; Not Applicable; Master of Applied Science; Department of Civil and Resource Engineering; Not Applicable; Lisa Kellman; Not Applicable; Rob Jamieson; Lauren SomersSalt marshes are recognized for the ecosystem services they provide as coastal nutrient filters and carbon sinks, but relying on salt marshes to attenuate nutrient pollution comes at the potential cost of enhanced greenhouse gas (GHG) emissions. In this study, we quantify and assess the trade-offs between the nutrient attenuation and carbon sequestration functions of salt marshes in Atlantic Canada. We conducted groundwater monitoring, surface and groundwater sampling, and GHG flux measurements at two salt marshes located adjacent to eutrophic estuaries in Basin Head, PEI and Rushton’s Beach, Nova Scotia. A hydrogeological model was developed to characterize the magnitude and pathways of nitrate transport into, and attenuation by, the Basin Head marsh. Our results indicate that nitrate loading is mainly via tidal flooding from the adjacent eutrophic lagoon and was estimated at 0.06 mmol N m-2 d-1 with 36% of input nitrate retained or converted in the marsh. The net climatic effect of average N2O and CH4 fluxes at Basin Head and Rushton’s Beach results in only a small reduction in the marshes carbon sink (8.3% and 5.0%, respectively).Item Open Access Microfinance, institution-building and development : an Egyptian case study(2008-12) Al Abassi, Soulafa; Not Applicable; Master of Development Economics; Department of Economics; Not Applicable; unknown; Not Applicable; Barry Lesser; Ruth Forsdyke; Ian McAllisterThe purpose of this thesis is: a) to understand the behaviour of microfinance institutions; b) to capture some of the issues that affect their behaviour and development; and c) to focus on 'healthy' institutionalization processes. Two methodologies were used to achieve this purpose: research and field exposure. From frameworks for analysis to the history and waves of the microfinance revolution; from understanding microfinance within a national context to understanding microfinance within an institutional context; to field cases from Cairo, Egypt (four borrowers and four credit officers)... this thesis has argued the necessity of evaluating the performance of microfinance institutions from within and without. A microfinance institution has to be 'healthy' from within and without to evolve in a 'healthy' manner; one cannot be achieved without the other. Furthermore, the indicators of 'health' should reflect both financial and non-financial data.Item Open Access The photosynthetic and respiratory physiology of Palmaria palmata (L.) Stackhouse, as affected by temperature, irradiance, total carbon dioxide, salinity and pH(1976-12) Robbins, Jonathan V.; Not Applicable; Master of Science; Department of Oceanography; Not Applicable; unknown; Not Applicable; unknown; James CraigieA chamber of variable volume was designed in which photosynthesis and respiration of the red alga Palmaria palmata could be measured under a variety of environmental conditions. The chamber was equipped with a polarographic oxygen electrode, pH electrode, injection port, and a sample removal tube. Using this apparatus, the effects of temperature, irradiance, total carbon dioxide concentration, salinity, and pH on the photosynthetic and respiratory rates of intact P. palmata plants were measured. The photosynthetic rates of seasonally adapted plants showed relatively little variation and no seasonal changes in respiration were detectable. P. palmata was shown to be a stenothermal plant, with a temperature optimum for photosynthesis of 10 and 15°c . . The photosynthetic rate became light saturated above 212 microEinsteins, with Pmax being temperature dependent. The compensation point for plants in late winter was found to be approximately 6.6 microEinsteins. Ambient sea water concentrations of inorganic carbon were shown to be insufficient to produce a maximum photosynthetic rate. By raising the concentration of total carbon dioxide to 6.0 - 7.0 mM, it was possible to stimulate photosynthesis by about 2.7 fold over the rate at normal concentrations. Maximum rates for photosynthesis and respiration were observed at a salinity of 32.0°/oo. A pH of 6.5 to 7.5 stimulated photosynthesis when compared to rates at pH 8.1, but below pH 6.5 photosynthesis dropped off sharply. At pH values above 8.0, a nearly linear decrease in the photosynthetic rate was observed.Item Open Access Heat flow : heat production studies in Nova Scotia(1974) Rankin, Douglas Stuart; Not Applicable; Doctor of Philosophy; Department of Earth and Environmental Sciences; Not Applicable; unknown; Not Applicable; unknown; Roy HyndmanInstruments and techniques were developed to measure heat flow in shallow and deep lakes. For the latter, they are an adaptation of the oceanic method using a lightweight thermogradient probe. Heat flow measured with this instrument is 1.51 ±0.23 μcal/cm 2 sec (63 ±9 mW/m 2 ) in Bras d'Or Lake, N.S. For shallow lakes, temperatures were measured at successive depths in the sediments to determine the thermal gradient. In Chocolate Lake and Card Lake the heat flows are 1.42 ±0.21 μcal/cm 2 sec (59 ±9 mW/m 2 ) and 1.92 ±0.29 μcal/cm 2 sec (82 ±12 mW/m 2 ) respectively. The former compares well with the heat flow in a nearby bore hole at Halifax, N.S. As a heat flow province (q = 1.08 + 9 A0) Nova Scotia appears to be distinct from others, especially the New England States heat flow province. The total heat flux and the components from heat flow provinces (q0 and DA0 ) when averaged for tectonic age decrease with tectonic age. It appears that erosion can account for the long term decay of the crustal component DA0 and a sinking low velocity zone can account for the decay of the mantle component q with age.Item Open Access Bioenergetics of the Australian giant cuttlefish (Sepia apama)(2001-02) Aitken, Jill P.; Not Applicable; Master of Science; Department of Biology; Not Applicable; unknown; Not Applicable; Alan Pinder; Dale Webber; Ron O'DorThe giant Australian cuttlefish is found on rocky reefs in the temperate waters of South Australia between Southern Queensland and North Western Australia (Norman et al. 1999). Sepia apama are known as the 'chameleon of the reef for their extraordinary camouflage ability. The cuttlefish are a favourite site for divers as they come out of hiding to investigate bright coloured SCUBA clothing and equipment. Although they are spectacular animals, little is known of their biology, behaviour and reproduction.Item Open Access Symmetry and Dynamics(1968-05) Tom, Jack; Not Applicable; Master of Science; Department of Physics & Atmospheric Science; Not Applicable; unknown; Not Applicable; unknown; D. KiangThe relation between symmetry groups and dynamics is studied, The study is concentrated on the two well known classical systems, namely, the Kepler problem and the isotropic harmonic oscillator. An extensive study of these two systems is conducted by applying the theory of transformations and the theory of Lie groups. The relation between symmetry and degeneracy will be shown and several methods to construct generators of the Lie groups 0(4) and SU(3) for the Kepler and harmonic oscillator problems are discussed.Item Embargo Inventing a Bountiful Earth: Settler Science in the Making of New Brunswick, 1763-1859(2024-10-28) Yeomans, Richard; Not Applicable; Doctor of Philosophy; Department of History; Not Applicable; Daniel Samson; Not Applicable; Aaron Wright; Erin Morton; Jerry BannisterInventing a Bountiful Earth explores the ways in which the production of natural and/or scientific knowledge shaped the development of the British settler colony of New Brunswick. It examines the ways in which both the British Imperial government and, after 1786, the House of Assembly of New Brunswick employed science, both its practical application and as an idea, in state formation. Science was an important tool used in the service of empire: through exploration; processes of drawing, surveying, or collecting; and disseminating knowledge about a particular locale via a web of scientific networks circulating across Britain’s expanding empire. Doing so gave Britain an invented dominion over vast swaths of land, including New Brunswick, and projected a form of sovereignty that reinforced the empire’s claim and access to resources across the globe that settler colonies later reproduced.Item Embargo Chronic Testosterone Deficiency Promotes Maladaptive Remodeling in The Hearts of Aging Male Mice(2024-10-28) Banga, Shubham; Yes; Doctor of Philosophy; Department of Pharmacology; Received; Dr. Céline Fiset; Yes; Dr. Ketul Chaudhary; Dr. James Fawcett; Dr. Susan HowlettTestosterone levels decrease with age in men, while the risk for cardiovascular diseases (CVDs) increases. Low testosterone levels are associated with CVDs. Testosterone primarily exerts its effects via androgen receptors (AR), which are also present in the heart. The impact of testosterone on the aging heart is not well understood. We hypothesized that chronically low testosterone levels in aging will have deleterious effects on heart structure and function. However, first we wanted to understand whether physiological testosterone levels in male mice can impact the heart. We found that both young and aged mice with higher testosterone levels had thicker left ventricular (LV) walls and higher LV mass. Testosterone levels in young mice did not influence systolic function, and young mice with higher testosterone levels had prolonged relaxation. By contrast, aged mice with higher testosterone levels had increased ejection fraction and shorter relaxation times. Next, we investigated the effects of chronic testosterone deficiency on heart structure and function across the life course of the mice by subjecting the mice to an early life gonadectomy (GDX). Our results indicated that by 18 months of age, GDX mice had smaller left ventricles and developed signs of diastolic dysfunction. Aged GDX mice also showed QT prolongation and more arrhythmias. Studies in isolated ventricular myocytes revealed increased triggered activity and prolonged action potentials caused by an increase in late inward sodium current (INa-L) in GDX mice. Blocking NaV1.8 channels normalized electrical activity. Since some older men take anti-androgenic drugs for conditions like prostate cancer, we also wanted to understand the effects of flutamide (AR antagonist) on aged hearts. Our results showed that flutamide treatment reduced LV size and mass. Flutamide also prolonged relaxation as well as slowed repolarization. Hearts from flutamide-treated mice also had lower rates of pressure development and decay and increased mRNA expression of certain calcium reuptake genes. Therefore, testosterone levels can influence cardiac structure and function and chronically low levels of testosterone or blocking androgen receptors can cause maladaptive structural remodeling, promote diastolic dysfunction, and slow ventricular repolarization in aging, increasing the risk of developing arrhythmias and heart failure with preserved ejection fraction.Item Embargo NUMERICAL INVESTIGATION OF DRILLING-INDUCED CORE DAMAGE IN HARD BRITTLE ROCKS(2024-10-27) Amiri Ramsheh, Fatemeh; Not Applicable; Doctor of Philosophy; Department of Civil and Resource Engineering; Not Applicable; Dr. Gabriel Walton; Yes; Dr. Gordon Fenton; Dr. Dmitry Garagash; Dr. Navid BahraniAt different design stages of underground excavations, cored samples are taken and tested to obtain geotechnical design parameters. When samples are retrieved from high-stress environments, damage in the form of micro-cracks may result in incorrect estimates of these parameters. This research investigates the impact of coring and overcoring on damage formation and the subsequent implications for geotechnical design parameters, using the well-documented case of the Underground Research Laboratory (URL) in Canada. It involves the generation of two-dimensional (2D) models: a) continuum-based heterogeneous (four mineral types) and homogeneous (one mineral) models; and b) hybrid continuum-discontinuum models consisting of triangular and Voronoi grains. The 2D models are calibrated against the laboratory properties of Lac du Bonnet (LdB) granite and subjected to an unloading (coring) stress path obtained from a 3D continuum model. The simulation results using continuum models highlight the importance of grain-scale property heterogeneity in the formation of unloading-induced damage. The simulated grain and grain boundary damage in the heterogeneous model result in a reduction in Young’s modulus and Unconfined Compressive Strength (UCS) by up to 29% and 22%, respectively. Using the hybrid method, it is demonstrated how grain-scale heterogeneities promote tensile stresses, leading to micro-crack initiation and opening, and subsequent nonlinearity in the stress-strain curve due to crack closure. In the next step, core drilling and overcoring are explicitly simulated using three-dimensional (3D) continuum and discontinuum models for various in situ stress magnitudes and borehole orientations at the URL. The tensile strength and crack initiation stress level of intact LdB granite are used to assess the potential for damage in the 3D continuum models. This, combined with the number of micro-cracks from the 3D discontinuum models, demonstrate an increase in potential for core and overcore damage with increasing depth, with fewer micro-cracks observed in samples drilled parallel to the major principal stress.Item Open Access Exploring Nitrogen Cycling in Lagos Lagoon, Nigeria: First Steps Towards an Integrated Monitoring Program(2024-08-18) Orji, Chukwuka; Not Applicable; Master of Science; Department of Earth and Environmental Sciences; Not Applicable; Dr. Suzanne Budge; Not Applicable; Dr. Carolyn Buchwald; Dr. Shannon Sterling; Dr. Douglas Wallace; Dr. Owen SherwoodLagos lagoon, a critical coastal ecosystem in West Africa, faces escalating pollution threats from dense human habitation, yet lacks a coordinated water quality monitoring program. This study aimed to provide an integrated baseline of nutrient levels using stable isotope analyses of carbon (δ¹³C) and nitrogen (δ¹⁵N) in sediments, biota, and water. In Chapter 2, δ¹³C values were lower in freshwater-influenced zones and higher in marine-influenced areas, reflecting differences in carbon sources. δ¹⁵N showed predictable trophic enrichment, with minor seasonal effects. Baseline δ¹⁵N values were within the natural range of seawater and soil nitrate, complicating attribution of anthropogenic impacts. Chapter 3 compared nutrient analysis between Canadian and Nigerian labs, revealing discrepancies potentially due to procedural differences. These findings offer a baseline for future monitoring and highlight the need for standardized methods and international collaboration to improve nutrient measurement accuracy and reliability in Lagos lagoon.Item Open Access ASSESSING THE COMPLETION TIME OF ON-SCENE RESCUE MISSIONS IN THE MARITIME AREAS OF THE CANADIAN ARCTIC USING MARINE OR AIR(2024-10-28) Rezaei, Parsa; Not Applicable; Master of Applied Science; Department of Industrial Engineering; Not Applicable; n/a; Not Applicable; Dr. Robert Brown; Dr. Colleen Dewis; Dr. Ronald Pelot; Dr. Floris GoerlandtIncreasing shipping in the Canadian Arctic enabled by climate change and economic growth heighten the need for efficient search and rescue (SAR) operations. Understanding rescue response times, including the maximum expected time of rescue (METR), is crucial. Current research lacks detailed metrics on rescue duration, which this study aims to address by modeling on-scene rescue mission durations based on various influencing factors. The research employs discrete event simulation (DES) and a Monte Carlo (MC) approach to estimate the duration of maritime rescue missions in the Canadian Arctic. It combines expert models to evaluate the weather factors and parameter uncertainties, using scenarios based on expert insights and literature. The DES model is tested across different Canadian Arctic locations. The research indicates that on-scene rescue missions in the Canadian Arctic are notably prolonged during winter compared to summer, with additional time required if icebreaking is needed in the vicinity of the incident. Key factors influencing rescue duration include wave conditions, visibility, air temperature, and wind speed. Adverse sea conditions and darkness extend on-scene rescue times. The study primarily considers rescues from lifeboats or life rafts and suggests future research should explore a broader range of rescue scenarios and vessel types.Item Open Access EXPERIMENTAL AND THEORETICAL STUDY OF SUSTAINABLE SANDWICH STRUCTURES WITH RECYCLED PET CORE(2024-10-18) Kassab, Raghad; Not Applicable; Doctor of Philosophy; Department of Civil and Resource Engineering; Not Applicable; Dr. Douglas Tomlinson; Not Applicable; Dr. Kyle Tousignant; Tamunoiyala Koko; Dr. Pedram SadeghianThis thesis investigates the use of recycled polyethylene terephthalate (R-PET) in the cores of sandwich structures to assess their suitability for integration as part of structural components. It commences with an experimental examination and comparative analysis of beams comprised of two configurations of R-PET cores: R-PET foam and R-PET honeycomb. Building on previous studies, which focused solely on a limited number of sandwich beams with PET fibre-reinforced polymer (FRP) facings and R-PET foam cores; this research expands the scope by systematically varying core thickness, density, and facing thickness across these configurations. To enhance the sustainability of the sandwich beams, the effect of utilizing bio-resin in the FRP composite facings was studied, examining how changes in polymer type impact the flexural strength of the beams. Additionally, this study incorporates finite element simulation alongside experimental testing of the sandwich beams to deepen the understanding of the structural properties and potential applications of these materials. The research progresses from beam bending testing and analysis, providing insights into the anticipated flexural performance of large-scale sandwich panels, to creating condensed guidelines for designing structural floors, roofs, and walls using these panels. The final phase involves testing full-scale sandwich panels, with each panel measuring 8 feet (2438 mm) in length, 4 feet (1219 mm) in width, and a core thickness of 6 inches (152 mm), under cyclic transverse loading, reflecting real-world dimensions and conditions. The experimental results are validated through modelling, leading to the creation of a detailed design table. This table provides essential guidance for designers, specifying the maximum allowable spans for the panels under typical dead and live loads, considering both strength and deflection criteria. Through these methods, the research offers insights and practical guidelines for the integration of R-PET core sandwich panels in structural applications.Item Open Access Design and Evaluation of LifeLink: A Persuasive Mobile Application for Caregivers Dealing with Suicidality(2024-10-16) Jha, Smriti; Yes; Master of Computer Science; Faculty of Computer Science; Received; N/A; Not Applicable; Dr. Bonnie MacKay; Dr. Mayra Barrera Machuca; Dr. Rita OrjiSuicide is a complex phenomenon wherein, in addition to the individual experiencing suicidal thoughts, its effects seep into many lives including their caregivers. Caregivers seek help everywhere but face unique challenges including limited access to timely resources and personal mental health struggles. Mobile health apps offer a promising solution, but addressing caregivers’ specific needs and challenges remains a concern. To address this gap, we developed LifeLink, a persuasive mobile app to support caregivers of individuals experiencing suicidal thoughts. The app was developed in three phases. First, we reviewed 80 existing suicide prevention apps from app stores and the academic literature to identify gaps and different persuasive strategies’ implementations using the Persuasive System Design (PSD) model. Second, based on review findings, we designed a low-fidelity prototype of LifeLink, implementing various evidence-based persuasive strategies. Through a survey and semi-structured interviews, 45 caregivers evaluated the LifeLink app prototype and shared their perspectives, challenges, needs when supporting individuals experiencing suicidal thoughts. We refined the app, incorporating caregivers’ feedback. Finally, we developed and evaluated LifeLink app in another study with 50 caregivers after a week of use. Results show that LifeLink is user-friendly, engaging, elicits a positive user experience and effectively empowers caregivers. The app’s persuasive strategies were found to be significantly persuasive in influencing caregiver behaviours toward supporting individuals experiencing suicidal thoughts. LifeLink usage was associated with improved mental wellbeing, increased mental health literacy and a more supportive environment for caregivers. We provide insights from two qualitative studies on caregivers’ needs and challenges, design recommendations for suicide prevention apps and highlight the importance of involving caregivers in the design process. Our findings contribute to a deeper understanding of the development of persuasive technology for suicide prevention that is user-friendly, impactful and has a positive user experience.Item Open Access Investigation of Heat Exchangers for a Solar Domestic Hot Water System(2024-10-10) Latouf, Elie; Not Applicable; Master of Applied Science; Department of Mechanical Engineering; Not Applicable; Michael Cada; Not Applicable; Ismet Ugursal; Peter AllenThis study evaluates the hydraulic and thermal performance of three heat exchangers used in hot water solar systems: shell and tube, shell and twisted tube, and brazed plate. The shell and tube heat exchanger is provided by Thermo Dynamics Ltd., while the brazed plate (type M14A) and shell and twisted tube (type PL45) models are supplied by SEC Ltd. SEC Ltd.'s data for the Brazed Plate and Shell and Twisted Tube heat exchangers are intended for high-power applications of 12 kW and above, however, this study investigates their performance at lower power levels, up to 3 kW. In addition to these three heat exchangers, the study also includes a comparative analysis with a shell and coil heat exchanger, as studied by (Gharbia, 2010). In the experimental setup, a 40% propylene glycol solution is circulated through one side of each heat exchanger, with water flowing through the other due to buoyancy-induced flow. The heat exchangers vary in surface area: Shell and Tube (0.36 m²), Shell and Twisted Tube (0.15 m²), Brazed Plate (0.14 m²). The study indicates that the brazed plate heat exchanger has superior thermal performance compared to both the shell and twisted tube as well as shell and tube configurations. However, it exhibits lower performance in comparison to the shell and 4-coils heat exchanger, which is currently used by Thermo Dynamics Ltd. for hot water solar systems.Item Open Access Bearing Capacity of Footings Under Vertical and Inclined Loads on Layered Soils(1978) Hanna, Adel M.; Not Applicable; Doctor of Philosophy; Department of Civil and Resource Engineering; Not Applicable; unknown; Not Applicable; J.D. Brown; H.G. Sherwood; G.G. MeyerhofThe bearing capacity of shallow foundations under axial vertical and inclined loads has been investigated for model strip and circular footings on layered soils. Two main cases have been considered, first, when the subsoil consists of a strong layer overlying a deep weak layer, and second, when a weak layer is overlying a deep strong layer. Extensive theoretical and experimental studies have been found in the available literature on footings under vertical loads on a strong layer overlying a deep weak layer. Except for Meyerhof's theory - (1974) for the case of footings under vertical loads on a weak layer overlying a strong layer, no other attempts have been made to develop a rational solution. Further, there does not appear to be any theoretical analysis or experimental data reported on footings on layered soils subjected to inclined loads. In this investigation, the case of a strong layer overlying a weak layer was simulated in the laboratory by testing footings on a dense and layer overlying loose sand, compact sand, and clay respectively. In the case of a weak layer overlying a strong layer, loose sand and compact sand overlying a dense sand were tested respectively. Homogeneous soils used in layer combinations were tested with the proposed footings under vertical and inclined loads. Results of these tests were verified according to established theories, and were used in the analyses of the test results of footings on layered systems. Further, these results provided an evaluation of the behaviour of the test materials. The ultimate bearing capacity of footings on the mentioned soil layers was noted to vary between the ultimate bearing capacities of the homogeneous upper and lower layers, Increasing the load inclination resulted in a decrease in this ultimate bearing capacity. New approach.es for the analysis were developed by extending Meyerhof's theories (1974). The present test results, test results of other researchers, and the available data were found to be in reasonable agreement with proposed theories. As a concluding part of the study, suitable design procedures are suggested for predicting the footing capacity in two layered soils and further research. points on the subject are recommended.Item Open Access Receipt books and the politics of food in early modern English women's writing(2008) Bassnett, Madeline; Not Applicable; Doctor of Philosophy; Department of English; Not Applicable; unknown; Not Applicable; Ronald Huebert; John Baxter; Christina LuckyjIn this discussion of printed and manuscript receipt books and women's literary writings, I show that a political discourse of food existed in early modem England, and that women were participants in this discourse. Over the course of the seventeenth century, receipt books communicated increasingly identifiable political perspectives, supporting or detracting from current regimes in prefatory material and even in recipes themselves. Frequently gendered, with the promotion of receipt books to women, and the establishment of women as integral to hospitable entertainment, the food discourse of receipt books is simultaneously adopted and developed by women writers of the period. The puritan advocacy of maternal nursing provided by Dorothy Leigh and Elizabeth Clinton, Countess of Lincoln, Lady Mary Wrath' s promotion of a Protestant plain-style dining practice in her romance the Urania, the use of food and fasting in the pamphlets of sectarian women Sarah Wight and Anna Trapnel, and the focus on hospitality in the diaries and memoir of Lady Anne Clifford and Ann, Lady Fanshawe reveal that food discourse is complexly integrated with numerous other cultural, social, and political concerns. The performance of the court, the practice and guidelines of hospitality and religious belief, the influx of foreign and novel foods, interpretations of health and physiological function, and visions of national identity all come into play as women turn to food to express their own dissatisfactions with current regimes, from James I to Charles II. Although rooted in domesticity, food and its rituals become important rhetorical indicators of women's critical engagement with the political sphereItem Open Access UNDERSTANDING SOCIAL VULNERABILITY IN AGING POPULATIONS: INSIGHTS ACROSS DIFFERENT HEALTHCARE SETTINGS(2024-10-10) Mah, Jasmine C; Yes; Doctor of Philosophy; Medical Research Graduate Program; Received; Dr. Kate Walters; Yes; Dr. Kenneth Rockwood; Dr. Janice Keefe; Susan Stevens; Dr. Melissa AndrewSocial vulnerability is the degree to which a person’s overall social circumstances leave them susceptible to adverse events, driven by the relative disadvantages from the conditions in which they were born, live, work and age. This thesis explores the complex nature of social vulnerability, conceptualizes its measurement through social vulnerability indices (SVIs), and examines its associations with health outcomes for older adults. Across eleven chapters, social vulnerability is explored using systematic and scoping reviews, qualitative interviews and quantitative data analyses in different populations of community dwelling and hospitalized older adults, primarily in Nova Scotia. This thesis begins with an exploration of the potential value of intervening to reduce social vulnerability by demonstrating complex interventions with a predominant social component were associated with improved function, better subjective health and lower hospital use. The next chapters describe the theory, method, and strengths of constructing a multiple level and multiple domain SVI and demonstrate feasibility in both a smaller clinical study and a larger population-based dataset. Using the SVI to understand how social vulnerability influences hospital outcomes among older adults in the emergency department showed that while frailty drove admission and mortality, social vulnerability prolonged hospitalization and increased risk of long-term care home entry. Within the hospital setting, qualitative interviews revealed healthcare providers’ perceptions of “socially admitted” patients including individual, institutional, and system challenges to providing patient centred care for this population. In later chapters, dynamic relationships are found between social vulnerability and mortality, home care hours, and long-term care home entry even after accounting for frailty and cognition. The findings presented in this thesis support the importance of considering social vulnerability for older adult health and use of healthcare and home care resources. The findings also suggested healthcare systems appear less responsive to older adults with high social vulnerability and potentially, unintentionally, facilitate care pathways towards institutionalization. Lastly, this thesis presents a model of caring for older adults at risk of frailty and social vulnerability across healthcare settings to guide future research, emphasizing the need for systems level thinking, comprehensive redesign, and proportional funding reform to effectively support the goal of aging-in-place in Canada.