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UNB Scholar is an institutional repository initiative of UNB Libraries intended to collect, preserve, showcase, and promote the open access scholarly output of the UNB community. Use UNB Scholar to explore specific collections, or search all content in the repository. Material submitted to the repository will also be freely discoverable online through Google and other major search engines.
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Recent Submissions
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.
Comparison of the environmental monitoring systems for protected areas of Canada and the European Union
(University of New Brunswick, 2024-10) Preuss, Ina Maite; Forbes, Graham; Sitzia, Tommaso
The global challenges of climate change and declining biodiversity have prompted many countries to develop nature protection strategies, collaborate in international organizations, and set common thresholds and goals. To measure the success of these efforts, effective monitoring systems are essential, but integrating data from different monitoring systems can be challenging. Canada and the European Union have developed advanced monitoring systems under varying circumstances. Both countries joined the Global Biodiversity Framework. To assess and compare these systems and their data, all parties must agree on basic standards. The individuals responsible for operating these systems play a crucial role in ensuring data completeness. Their work must be evaluated based on its complexity, adaptability, and comparability. This thesis compares the monitoring systems at three levels of governmental structure, assessing them against fundamental criteria with the aim of identifying overlapping areas and proposing enhancements. A unified approach could significantly enhance global biodiversity monitoring efforts.
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.