Open Theses & Dissertations

Permanent URI for this collection

https://unbscholar.lib.unb.ca/handle/1882/12778

Browse

Now showing 1 - 20 of 2008

Spherically symmetric space-times in effective LQG
(University of New Brunswick, 2024-12) Kelly, Jarod; Seahra, Sanjeev; Wilson-Ewing, Edward
Black holes are among the most enigmatic objects in our universe. Although many decades have been dedicated to their study, illuminating several of their key features, there is still very little understood about what happens at their center. At this location general relativity leads to a singularity and it is widely believed that a theory of quantum gravity is necessary to understand the structure of space-time in the vicinity of this point. In this thesis, we discuss the application of a candidate theory of quantum gravity, namely loop quantum gravity (LQG), to study spherically symmetric black holes. We start in Chapter 2 by developing a framework for an effective LQG description of spherically symmetric black holes in vacuum and analyze the structure of this space-time in depth. In Chapters 3 and 4, we extend this framework by including matter and study black holes that form due to gravitational collapse. We study the dynamics and causal structure of these space-times in depth to uncover new black hole properties that are not captured by the classical theory including: a space-time that is free from strong singularities (although weak singularities in the form of shell-crossings can and do form quite generically) and the formation of shockwaves that will eventually move beyond the outer horizon, marking the “death” of the black hole. Further, we estimate the black hole lifetime to be on the order of M2, where M is the black hole mass.
Seasonal thermal plasticity of cardiac function in temperate and Arctic fishes with different overwintering strategies
(University of New Brunswick, 2024-12) Williams, Emily; Speers-Roesch, Ben
Fishes can experience large thermal variation over rapid and prolonged time scales, which challenges critical physiological functions. I investigated the seasonal thermal plasticity of acute temperature responses of heart rate and cardiac adrenaline regulation in temperate and Arctic fishes with different overwintering strategies. Though their distinct overwintering strategies impose different cardiac demands, the winter-dormant cunner and winter-active brook char showed a relatively similar ability to acclimate heart rate and adrenergic sensitivity to three seasonally relevant temperatures in the laboratory. In contrast, wild winter-active lake trout from the central Canadian Arctic showed largely consistent thermal performance of heart rates between seasons; however, seasonal changes in the cardiac cycle were apparent in winter. Overall, my studies indicate the potential influence of overwintering strategy on the thermal limits of cardiac function and highlights the wide diversity of cardiac thermal plasticity among fishes along with the importance of conducting physiological research in the field.
Symmetric integer linear programming with a core point approach
(University of New Brunswick, 2024-11) Banihashemi, Seyyedemahsa; Bremner, David
This thesis explains the implementation of two existing algorithms, to solve symmetric integer linear programs (ILPs), using PyScipOpt, a Python interface to the SCIP optimization software. The existing approach focuses on a special feature of circulant matrices to develop new constraints for solving these problems, based on core points, a subset of integral points in symmetric ILPs. We made some modifications to the algorithms. This was achieved by constructing and utilizing essential sets more effectively, calculating the value of big M, and modifying constraints when the matrix is singular. Additionally, we used the two algorithms to compare the outcomes for problems solved by Knitro with those same problems solved using SCIP. We test the algorithms with both feasible and infeasible instances, varying in the number of variables. Moreover, we tested infeasible ILP problems with different polytope shapes, using Algorithm 2, CPLEX, and SCIP to compare the performance of these three solvers.
A centralized voltage control strategy to mitigate effects of highly intermittent PV generation in distribution network
(University of New Brunswick, 2024-11) Khan, Zahid Ali; Diduch, Chris P.; Cardenas, Julian L.
High penetration of photovoltaics in distribution networks creates voltage regulation problems. The local volt-watt and volt-var control of PVIs are capable of voltage regulation however, their uniform control curves lead to unfair utilization of active and reactive power in voltage stability. This unfairness in active and reactive power minimizes the total active power injection into the grid. This research considered a centralized optimization algorithm in an attempt to reduce the unfairness in utilization of active and reactive power in voltage stability. An optimization algorithm is run to set the PVI volt-watt and volt-var control curves setpoints to minimize the unfairness with the objective of prioritizing reactive power capabilities and maximizing active power injection in distribution networks. Test results indicate that the centralized strategy successfully reduces the unfairness in utilization of available resources as well as maximizes the total active power injected into the system.
Nursing shortages and quality of care: The perspectives of New Brunswick registered nurses
(University of New Brunswick, 2024-11) Moulaisson, Jennifer; O'Donnell, Sue
New Brunswick (NB) is facing an unprecedented nursing shortage, which has raised paramount concerns regarding its impact on registered nurses (RNs), the quality of care they deliver, and their overall retention within the healthcare system. However, existing literature surrounding this domain remains limited, highlighting the need for further investigation. This grounded theory study explores the experiences of eight RNs in NB hospitals, focusing on how they navigate delivering quality care in the context of the current nursing shortage. Through in-depth, semi-structured interviews and grounded theory analysis, the study develops a middle-range theory, defining nursing shortage and quality care from RNs’ perspectives. Findings highlight facilitators, barriers, and strategies for quality care, offering insights to improve RN well-being and patient care quality in NB hospitals. This research informs strategies that can strengthen the well-being of the nursing workforce and elevate the quality of care provided in NB hospitals.
Naturalistic countersinging and movement for the hermit thrush (Catharus guttatus)
(University of New Brunswick, 2024-11) McLean, Luke; Roach, Sean
The study of birdsong helps with conservation strategies, the neuroscience of vocal learning, and our understanding of communication. Many interactive singing behaviours have been demonstrated among songbird species. Evidence suggests that the dawn chorus is a time when communities of birds negotiate their social relationships, but the specific communication dynamics remain unclear. This study explored singing during the dawn chorus for the hermit thrush. Using microphone arrays, researchers were able to capture territorial singing and triangulate bird locations and movements. Neighbouring birds were found to be regularly interacting through song overlap, frequency match avoidance, conventional matching, and adjustments of song rate, song switch rate, and syntax consistency. Behaviours also varied with distance between birds, suggesting a complex singing and movement dynamic. This study contributes to our understanding of the hermit thrush, songbird communication, and territorial behaviour.
A new low field magnet for Overhauser Dynamic Nuclear Polarization magnetic resonance studies
(University of New Brunswick, 2024-11) Morin, Devin Mathieu; Balcom, Bruce J.
Low-cost portable magnetic resonance (MR) instruments have significantly evolved over the past several decades, offering diverse applications in medical diagnostics, material science, and beyond. Instruments for MR that employ permanent magnets are advantageous given that they are low-cost, portable, and simple to construct. This is not true for conventional superconducting magnets. Improvement of the instruments and measurement techniques employed in portable MR is essential for better material characterization. In this thesis, we present several portable magnet designs, based on permanent magnets, with diverse applications. An essential element of each design is that they are simple to construct, encouraging their use by others. The first magnet design is an improvement upon the existing three-magnet array design. We employ computer simulation to optimize the magnet placements for a large homogenous region displaced far from the magnet surface. We explored the usage of this instrument for measurement of liquid samples and water-oil content determination. The second magnet design is termed the CLAM (Ceramic Low-field Angled Magnet) magnet. It was employed for the dual purpose of flow velocity measurement and Overhauser Dynamic Nuclear Polarization (O-DNP). Ceramic magnets offer the advantage ii of being cost-effective and supporting efficient O-DNP enhancement due to their lower field strength. The design naturally led to two configurations: a homogeneous magnet for O-DNP, and a constant gradient magnet for flow measurements. The ability to spatially enhance 1H spins through local O-DNP enhancement was explored in the gradient configuration, which continued in the following study. The culmination of this work is demonstrated through O-DNP selective enhancement of water or oil. The free-radical species 4-Hydroxy-TEMPO and 4-Hydroxy-TEMPO benzoate were employed to selectively enhance the signal from oil or water based on the solubility of the TEMPO agent. The preferential solubility of the free radical species in a chosen phase permitted the enhancement of a single species of interest. A new 1D profiling CLAM magnet design was created to image O-DNP selective enhancement. Studies of rock core flooding confirmed and validated this technique for exploring material characterization beyond what was previously possible with standard MR techniques.
An evaluation of the first safer supply program in New Brunswick: The River Stone Recovery Centre
(University of New Brunswick, 2024-11) Thornton, Adrienne; Brunelle, Caroline
In response to the opioid poisoning crisis, safer supply programs (SSPs) have been implemented across Canada, and provide individuals access to prescription medications as an alternative to the illicit drug supply. River Stone Recovery Centre’s injectable opioid agonist treatment program is the only SSP currently operating in New Brunswick. Semi-structured interviews were completed with participants (N = 22), and follow-up interviews (N = 18) were conducted six months later, to assess participant’s experiences and outcomes related to their program involvement. Participants reported positive program experiences and impacts, such as improvements in quality of life, that were attributed to the non-stigmatizing care they were receiving, and to the low-threshold, harm reduction approach of the program. The results from this study demonstrate the positive impact of SSPs in reducing the harms associated with the opioid toxicity crisis, but also highlight areas of unmet needs that can inform harm reduction strategies.
Learning based collaborative task allocation
(University of New Brunswick, 2024-10) Muntaha, Mahjabin; Song, Wei
In the digital era, Mobile Crowdsensing Systems (MCS) utilize mobile and wearable devices for large-scale data collection, forming participatory sensor networks. A primary challenge in MCS is collaborative task allocation, where multiple workers must coordinate to complete tasks. Our approach integrates workers’ social connections, recognizing that those with similar backgrounds collaborate more effectively. We frame this task allocation problem as a graph-based combinatorial optimization task, complicated by spatial, temporal, and social constraints. To ad dress the limitations of traditional heuristics, we propose a Heterogeneous Graph Attention Network-based Double Deep Q-Network (HGDQN). The HGDQN agent autonomously explores and learns to address complex scenarios by capturing nuanced worker-task relationships through subgraphs within the heterogeneous graph. Experimental results show that HGDQN surpasses traditional heuristic methods such as Greedy and ACO methods in scalability, adaptability, and generalization, providing a robust solution for collaborative task allocation in MCS.
It’s all in there, no it isn’t: A Critical Discourse Analysis of the Adolescent Education Programme of India as it relates to gender and sexuality hierarchies
(University of New Brunswick, 2024-10) Singh, Rohina; Rogers, Matt W.B.
This qualitative study takes up Critical Discourse Analysis and thematic document analysis to show how power operates through taken-for-granted schooling policies and practices in India. Specifically, this work addresses power by identifying gaps and inequitable discourses in the Adolescent Education Programme (AEP) regarding gender and sexuality. My data analysis has revealed three salient themes, all of which act as mechanisms of gender inequity: (i) the perpetuation of patriarchal gender norms, (ii) the privileging of heteronormativity, and (iii) biases and discrimination against sexual and gender minorities. Sexuality education geared toward youth in India has the potential to address culture-specific gender norms and attitudes before they crystallize. However, for this to happen, it is vital for Indian youth to engage critically with the discourses sexuality education enacts and perpetuates by critiquing, challenging, and questioning issues of power, marginalization, and representation.
The effects of language use on responses in English/East Asian bilingual individuals: A meta-analysis
(University of New Brunswick, 2024-10) Schriver, Jordan; Perunovic, W.Q. Elaine
According to the linguistic relativity hypothesis, language use can influence the way individuals interact with the world (Whorf, 1956). Compelling evidence for this claim comes from research on bilingual individuals. Specifically, experimental studies in which bilingual individuals have been randomly assigned to communicate in one language or another have shown that language use can affect the way that bilingual individuals think (e.g., Lechuga & Wiebe, 2011), feel (e.g., Alvarado & Jameson, 2011), and behave (e.g., So, 2010). An attempt has not yet been made to integrate these findings, and establish a unified understanding of how the language used by bilingual language users affects their behaviours. Therefore, with this dissertation I addressed this gap by conducting a systematic review and meta-analysis, wherein I attempted to gather all available published and unpublished research up until 2022 in which bilingual individuals proficient in English and an East Asian language were assigned to complete a culturally relevant task in either language, and in which outcomes from the task in each language were compared. Through multilevel meta-analysis including 269 effect sizes drawn from 63 independent samples reflecting the responses of 6693 participants, I found an overall significant effect (g = .27), indicating that when language is manipulated, responses are generally consistent with the cultural norms associated with the language being spoken. The magnitude of this language effect, however, was moderated by the East Asian language being used, and the Task Type under examination. The language effect was not moderated by the Design of the study, Language Acquisition Style, the Country or the City in which the study took place. This meta-analysis offers a synthesis of an existing research program and poses intriguing questions that warrant investigation in future studies.
Compilation-based spatial query processing
(University of New Brunswick, 2024-10) Sahni, Rahul; Ray, Suprio
The proliferation of spatial data applications and rising spatial data volumes demand efficient processing capabilities. Although most relational databases support spatial extensions of SQL, they offer limited scalability. Traditional relational database follows a pull-based model of query processing. This is inefficient for processing large volumes of data. Specialized systems, such as those extending Hadoop and Spark, improve scalability but often lack comprehensive SQL support or suffer from the overheads of the pull-based model. This thesis introduces a distributed spatial query processing system using the Push-based query compilation approach, generating C++/UPC++-based query plans for both single node and distributed execution on a high-performance framework using the Partitioned Global Address Space paradigm. It also proposes two new morsel-driven parallelism algorithms for scalable spatial query execution. Experiments on real-world datasets show significant performance gains over leading systems, including Apache Sedona, Citus - a distributed database based on PostgreSQL, and PostgreSQL in single-node configurations.
The Lock: A play about wrongful convictions
(University of New Brunswick, 2024-10) Leggott, Rosie; Finlay, Triny; Falkenstein, Len
Imagine growing up poor in Canada in the 1950s. Your father has PTSD from the war, your mother struggles with addictions, and your best friend dies in your arms. You are sixteen years old when you are sentenced to life in prison for a murder you didn't commit. This is what happens to Kenneth in The Lock. The Lock is a two-act stage play intermixed with poetry that argues the case for modern ideas of prison abolitionism. Kenneth reflects on his story while suffering from Alzheimer's disease. His broken collection of memories confronts issues of rehabilitation, recidivism, and the human cost of incarceration. The integration of poetic elements within the play serves as a powerful medium for conveying the raw humanity and poignant introspection of those living within the confines of the prison system. The Lock challenges narratives of Canadian exceptionalism, highlighting the nation's history of unjust incarcerations, and shows just how much it takes to break the human spirit.
Development and prototyping of a biologically inspired knee prosthesis
(University of New Brunswick, 2024-10) Lufkin, Jacob Andrew; McGibbon, Chris; Carretero, Juan
A design for a biologically inspired knee prosthesis is presented. The design comes from using spring-driven devices in an antagonistic fashion to control both the position and stiffness of the knee joint. This work presents a proof-of-concept design that seeks to both develop an understanding of how to design and build a usable model and compare that physical model against a simulated model of the knee. The design was made in a pragmatic fashion and sources of error were mitigated during development. The final design following an intensive iterative design project allowed for quasi-static stiffness testing. The model was compared against simulated data. The model showed stiffening behavior and control over the position of the tibial component. It also showed a high amount of correlation to the simulated data. This holds promise for the future of the design, as it is proven to be feasible to build and simulations of optimized geometries can be trusted to yield valid data.
Multi-patch integrodifference models and their eigenvalue problems in spatial ecology
(University of New Brunswick, 2024-10) Beykzadeh, Ali; Watmough, James
In the realm of spatial ecology, we grapple with fundamental questions: How can we design effective nature reserves to safeguard the survival of species? In the context of fisheries, how wide can a fishing zone be without compromising the stability of fish populations? These inquiries have fueled my motivation to delve into the subject matter of this thesis. While we acknowledge that precise answers to such questions remain elusive, I have endeavored to contribute to our understanding of these critical issues. Our journey begins with an exploration of integrodifference equations (IDEs) in spatial ecology in Chapter 1. These mathematical models serve as powerful tools for unraveling the intricate spatial and temporal dynamics of populations characterized by discrete generations and continuous spatial domains. Imagine a population confined to a single isolated patch — a scenario akin to a lake surrounded by hard boundaries. Within this patch, there exists a gap devoid of reproduction, effectively separating the population. Consider, for instance, a protected fishing zone within a lake. Our focus in Chapter 2 lies on understanding the persistence of such populations. We model their life cycles using IDEs and present a method to calculate the maximum allowable gap size that ensures population persistence. The concept of critical patch size takes center stage in Chapter 3. It refers to the minimum favorable area below which a population faces the risk of extinction. Our investigation accounts for the demographic and dispersal traits of individuals, recognizing that these traits may vary across patches. Surprisingly, we find that the smallest critical patch size occurs when individuals exhibit a propensity to leave the patch. Conversely, the largest critical patch size arises when boundaries are more restrictive, limiting the chances of individuals leaving the patch. In the patchy landscape, Chapter 4 introduces an approximation method that simplifies equilibrium population calculations. Our approach involves a form of the redistribution approximation tailored for piecewise continuous kernels. The accuracy of our estimate improves as movement biases near patch boundaries intensify. Key factors influencing our estimate include the growth term’s derivative and the deviation of the equilibrium solution from its average across patches.
Rejecting maternal healthism: A grounded theory
(University of New Brunswick, 2024-10) Baxter, Carolyn; Taylor, Petrea
Many women of childbearing age are living with a higher BMI. Challenges among women living with a higher BMI as they become mothers include experiencing weight stigma and judgment from health care providers. Seven women were interviewed, and a grounded theory methodology is used to understand how women cope with the increased physiological risks and the stigma associated with obesity as they become mothers. Maternal healthism places the responsibility for the health of the baby on maternal behaviours leading to feelings of shame when mothers are unable to meet the expectations of what is “healthy.” Rejecting maternal healthism is a productive response to negative judgment; women living with a higher BMI recognize that the problem is maternal healthism, not their body, and not their ability to be a good mother. Education of health care providers related to rejecting maternal healthism can help to better support women as they become mothers.
Key barriers and career challenges that hinder women from advancing in New Brunswick Information and Communication Technology (ICT) sector
(University of New Brunswick, 2024-10) Abbasi, Katya; Shaikh, Ibrahim
This study aims to understand better the key barriers and challenges that limit women’s participation in senior leadership roles within the Information and Communication Technology (ICT) sector in New Brunswick, including identifying effective response strategies. This study adopted a holistic approach to identify the issue's root cause, consisting of a three-level dimensional analysis. Empirical findings were based on the qualitative analysis of a sample of 27 interviews. Interviews were not limited to women operating in the ICT sector; ecosystem stakeholders, such as Not-for-Profit Organizations (NPOs), public officials, governmental representatives, and the representatives of companies in which those women operate were also interviewed. Significant discrepancies were found regarding the description of the issue by different segments. Emerging findings in the context of the New Brunswick ecosystem, such as “Imposter Syndrome” and “Leaky Boat Syndrome,” were considered key barriers to women’s advancement.
Remembering collective violence: A study of the memories of violence for Indian Sikh and Muslim immigrants in Canada
(University of New Brunswick, 2024-10) Maitreyi, Misha; Holtmann, Cathy
This dissertation examines individual and collective memories of collective violence among Indian Sikh and Muslim immigrants in Canada, focusing on the anti-Sikh violence of 1984 and the anti-Muslim violence of 2002 in India. Drawing on qualitative interviews with 19 participants, the research examines the composition of collective memories, the significance of these memories and their impacts on the daily lives of Sikh and Muslim immigrants in Canada. By integrating concepts of collective memory (Halbwachs, 1992), social memory studies (Olick & Robbins, 1998), revised versions of collective consciousness (Durkheim, 1984[1893]) and collective effervescence (Durkheim, 1965[1912]), and religion as power (Woodhead, 2011; Juergensmeyer, 2010; Friedland, 2001), this study underlines participants’ recollections of mob violence, gendered violence, survival strategies, diverse forms of trauma they have endured and still feel while living in Canada. The findings reveal a common narrative regarding the role of state institutions in orchestrating the violence in both cases. Religious nationalism was deliberately deployed in the 2002 violence against the Muslim minority, moving away from the principles of secularism towards the formation of a Hindu ethnostate. The analysis shows commonalities in the recollection of mob violence and their characteristics such as the use of fire and violence against women. I also highlight how participants’ recollections of similar survival strategies foster collective solidarity and resilience within the communities. Additionally, the participants view the violence in political terms rather than attributing blame to any religion or religious community. Ultimately, by analysing the stories and experiences of violence, I draw parallels with scholarly perspectives on mob violence, shared affect, the political nature of violence, and the instrumentalisation of religious nationalism to demonstrate that while memories can be transient in nature, collective memory persists and reveals significant truths consistent with scholarly explanations. By underscoring the importance of understanding collective memories, I argue that such experiences of collective violence influence perceptions of democracy, minority identities, and human rights as they impact the relationship of immigrants with their countries of origin and residence.
Processing, microstructure, and mechanical properties of additively manufactured IN718 nickel-based superalloy
(University of New Brunswick, 2024-10) Hasani, Navid; Mohammadi, Mohsen
Inconel 718 (IN718) is a widely used superalloy in aerospace applications requiring high strength at elevated temperatures. This thesis comprehensively explores the processing, microstructure, and mechanical behavior of IN718 manufactured by wire arc additive manufacturing (WAAM) and via laser powder bed fusion (LPBF). First, WAAM-produced hybrid IN718-S275 components were investigated, examining interfacial characteristics and texture evolution. Notably, laves phase persistence was observed near the interface even after solution treatment. Neutron diffraction was used to validate the texture of the hybrid components where a strong texture parallel to the build direction in WAAM-IN718 was identified. Elastic-field models were utilized to understand dislocation mobility and Peierls-Nabarro stress, elucidating the role of heat treatment in modifying mechanical properties. Next, differential scanning calorimetry (DSC) was employed to optimize the solutionizing temperature for the complete dissolution of undesirable phases (δ and laves) in LPBF-IN718, with subsequent microstructural characterization. This led to the elimination of micro-segregation and significant Laves dissolution, resulting in a hardness comparable to wrought IN718 alloys. Furthermore, the dynamic deformation behavior of LPBF-IN718 was studied under various elevated strain rates. AMS 5664 heat treatment resulted in a remarkable 28% increase in ultimate compressive strength. Microstructural analysis revealed the presence of strengthening γ" and γ' phases in abundance, and high-density dislocation networks was observed. The influence of strain rate on grain size, texture, and adiabatic shear band formation was thoroughly investigated. The research presented in this thesis provides a comprehensive understanding of how processing techniques and post-fabrication treatments influence the microstructure and mechanical behavior of IN718. This knowledge contributes to optimizing manufacturing processes and developing tailored IN718 heat treatments for aerospace applications. Additionally, this work offers valuable insights into the mechanical response of additively manufactured IN718 under high-strain-rate loading conditions, enhancing the understanding of its performance in critical aerospace and engineering applications.
Privacy-preserving data analytics in advanced metering infrastructure utilizing TEE
(University of New Brunswick, 2024-10) Kariznovi, Arash; Mandal, Kalikinkar
With the rise of the smart grid, modern electrical grids now support two-way communication of energy and data, enabling system optimization through data analytics. However, this also introduces cybersecurity vulnerabilities. While research has focused on using smart meter data to enhance grid performance, security and privacy concerns remain underexplored. This research proposes a secure and privacy-preserving framework for smart meter data transmission and analytics. It combines lightweight cryptography and transport layer security for end-to-end data protection, while Intel SGX ensures private data processing in the cloud. We implemented an efficient LSTM model for energy consumption prediction, demonstrating the framework’s practicality. Our approach balances security, privacy, and functionality, allowing data owners to retain control while leveraging third-party cloud resources.

Browse

Recent Submissions