Theses, Dissertations, and other Required Graduate Degree Essays

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This collection contains digitized SFU theses except for those theses submitted within the last 12 months. If you cannot find the thesis you are looking for please search Recently Submitted Theses as it may be a recently submitted thesis and thus not yet available in Summit.

River network structuring of climate and landscape effects in salmon watersheds

Author: 
Date created: 
2019-01-09
Abstract: 

Climate change is altering historic patterns of temperature and precipitation worldwide with significant implications for the abiotic and biotic dynamics of river ecosystems. Flowing downhill, precipitation aggregates into creeks, streams and eventually rivers, forming a branching network over the landscape architecturally similar to the branches, limbs and trunk of a tree. Linking disparate locations, these river networks integrate the varied expressions of climate within a watershed. Thus, the river network offers a framework for understanding how spatial patterns of climate are organized and become manifest in rivers. By considering the river network's structuring of climate and landscape interactions, we might better understand how climate and land-use change impact river ecosystems and more clearly identify particularly vulnerable biota. In chapter 2, I examine how river networks dampen signals of climate change in hydrologic flow by integrating varied flow trends from upstream. I demonstrate that by integrating a diverse climate portfolio, the network accumulates changing flow regimes of different volatility, direction and magnitude, such that on average downstream climate change trends are moderated. In chapter 3, I consider the match-mismatch potential of juvenile salmon migrating towards the springtime zooplankton resource pulse in the estuary. I show that populations further from, and whose climate is more dissimilar to, the estuary, are more likely to miss the peak zooplankton bloom. These findings suggest migratory distance influences phenological mismatch risk among populations. My fourth chapter develops an unsupervised machine learning method for cleaning stream temperature data to facilitate big data studies. In chapter 5, I gathered temperature data at over 100 locations throughout a watershed the size of Ireland, over 4 years at 2-hour intervals resulting in over 1 million data points. These data informed a spatial stream network model that quantified how landscape features and river connectivity control seasonal temperature dynamics. These temperature dynamics across space and time revealed that different adult salmon migrations have very different exposures to warm temperatures. Collectively, these findings illustrate that river networks: 1. integrate and dampen signals of climate change, 2. structure phenological match-mismatch patterns and 3. organize thermal exposure potential of biota.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jonathan Moore
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) Ph.D.

On the role of possibility in action execution and knowledge in the Situation Calculus

Author: 
Date created: 
2019-01-11
Abstract: 

Formalization of knowledge is an important aspect of reasoning about change. We review how knowledge is formalized in the Situation Calculus (a logical formalism for reasoning about action and change) and discuss the problems that occur when unexecutable actions (those actions whose preconditions are not met at the time of execution) are involved. We then provide a generalized framework that addresses these problems by tracing back source of the problem to the answer provided to the Frame Problem in the Situation Calculus. We develop a more generalized form for Successor Sate Axioms based on the new account of the solution to the Frame Problem and show how this solves the problems related to involvement of unexecutable actions.

Document type: 
Thesis
File(s): 
Senior supervisor: 
James Delgrande
Department: 
Applied Sciences: School of Computing Science
Thesis type: 
(Thesis) M.Sc.

Chinese art worlds in China and abroad: Art Collectors, institutions and cultural identity

Author: 
Date created: 
2019-01-07
Abstract: 

Over the past decades, Chinese art collectors have drawn worldwide attention to their active acquisitions of artworks in both domestic and international art markets. On the one hand, the development of Chinese modern art and contemporary art has been accompanied by anxiety and uncertainty since the beginning of China’s search for modernity. On the other hand, with China’s reopening to the outside world, particularly concerning its economy, the rapid development of China’s art market and involvement in the international art market have brought China to the spotlight of the international art world. Hence, the impacts of the dynamic art market driven by Chinese art collectors in China on shaping the development of contemporary Chinese art and the perceptions of contemporary Chinese art domestically and internationally is worth exploring.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jan Marontate
Department: 
Communication, Art & Technology: School of Communication
Thesis type: 
(Thesis) M.A.

Installation, commissioning, and acceptance measurements of EMMA

Author: 
Date created: 
2018-12-13
Abstract: 

The ElectroMagnetic Mass Analyzer EMMA is a vacuum mode recoil mass spectrometer that is capable of horizontally dispersing reaction recoils according to their mass/charge ratio at its focal plane station. The recoils enter into two consecutive gas-filled proportional counters, one that detects their positions and the other to measure their energy loss per unit length as well as the residual energy so that the recoils may be uniquely identified. EMMA was designed to exhibit excellent beam suppression so that reaction channels that are weakly populated may be extracted from the unreacted beam and high-yield background channels. EMMA has undergone several commissioning tests to determine how it performs compared to its design specifications. This thesis covers a subset of the tests which involved using a radioactive alpha source as well as accelerated ion beam backscattering to determine its energy/charge and angular acceptances as well as its mass/charge dispersion and acceptance as part of the commissioning of the spectrometer.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Bernd Stelzer
Department: 
Science: Department of Physics
Thesis type: 
(Thesis) M.Sc.

Sub-regional variation in the structure, composition and ecology of old-growth floodplain forests in the Pacific Coastal Temperate Rainforest

Author: 
Date created: 
2018-12-06
Abstract: 

A strong understanding of regional variation in structure and composition of old-growth floodplain forests and ecosystem drivers is critical for improving riparian old-growth management. We reviewed the literature to develop a framework to evaluate these and the relative roles of climate, disturbance, other drivers and their interactions. We then examined forest structure from 17 plots across ~11° of latitude along the northern Pacific Coastal Temperate Rainforest (PCTR). Mean annual temperature and precipitation were the most influential drivers of stand structure. Several flood proxies correlated with structural attributes suggesting that hydrological disturbance is a key driver of structure, likely driving greater variability among floodplain stands than upland stands. Northern plots showed slower stand development compared to southern plots, differences in structure suggest a need to re-evaluate sub-regional boundaries of the PCTR. Delineating sub-regional boundaries are important for monitoring and predicting how climate change will affect these forests and their disturbance regimes.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Ken Lertzman
Department: 
Environment: School of Resource and Environmental Management
Thesis type: 
(Project) M.R.M. (Planning)

3D architecture electrodes for energy storage applications

Author: 
Date created: 
2018-12-10
Abstract: 

Micro-scale energy storage devices have been developed for the demand of required energy autonomy of the portable and small-scale electronics. One main drawback in realization of micro-scale energy storage devices is limited areal capacitance due to low material loading per unit area on the substrate. 3-D electrodes with high aspect ratio could be promising strategy to overcome this, resulting in higher device performance. Specially, 3D printing technology offers numerous advantages to generate 3D electrodes for energy storage devices, which includes time-saving, cost-effective manufacturing, and realization of tailorable complex electrode designs. In this thesis, novel hierarchical 3D designs were printed by photo-curable 3D printing. Photo-curable resins with conductive fillers were optimized for conductive 3D electrode formation. Finally, energy storage devices with the hierarchical 3D electrodes have been demonstrated for the application of micro-supercapacitors (MSCs). The fabricated 3D hierarchical electrodes demonstrated low electrical resistance to be used as feasible MSCs electrodes. Energy storage from redox reactions was demonstrated in 3D architecture electrodes designed with mechanically durable 3D octet trusses.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Woo Soo Kim
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Statistical inference using large administrative data on multiple event times, with application to cancer survivorship research

Author: 
Date created: 
2018-12-20
Abstract: 

Motivated by the breast cancer survivorship research program at BC Cancer Agency, this dissertation develops statistical approaches to analyzing right-censored multivariate event time data. Following the background and motivation of the research, we introduce the framework of the dissertation, and provide a literature review and a list of the research questions. A description of the motivating study data is then given together with a preliminary analysis before presenting the proposed approaches as follows. We consider firstly estimation of the joint survivor function of multiple event times when the observations are subject to informative censoring due to a terminating event. We formulate the potential dependence of the multiple event times with the time to the terminating event by the Archimedean copulas. This may account for the informative censoring and, at the same time, allow to adapt the commonly used two-step procedure for estimating the joint distribution of the multiple event times under a copula model. We propose an easy-to-implement pseudo-likelihood based estimation procedure under the model, which reduces computational intensity compared to its MLE counterpart. A more flexible approach is then proposed to handling informative censoring with particular attention to observations on bivariate event time potentially censored by a terminating event. We formulate the correlation of the bivariate event time with the censoring time by embedding the bivariate event time distribution in a bivariate copula model. This yields the convenience of inference under the conventional copula model. At the same time, the proposed model is more flexible, and thus potentially more appropriate in many practical situations than modeling the event times and the associated censoring time jointly by a single multivariate copula. Adapting the commonly used two-stage estimation procedure under a copula model, we develop an easy-to-implement estimator for the joint survivor function of the two event times. A by-product of the proposed approaches is an estimator for the marginal distribution of a single event time with semicompeting-risks data. Further, we extend the approach to regression settings to explore covariate effects in either parametric or nonparametric forms. In particular, adjusting for some covariates, we compare two populations based on an event time with observations subject to informative censoring. We conduct both asymptotic and simulation studies to examine the consistency, efficiency, and robustness of the proposed approaches. The breast cancer program that motivated this research is employed to illustrate the methodological development throughout the dissertation.

Document type: 
Thesis
File(s): 
Senior supervisor: 
X. Joan Hu
John J. Spinelli
Department: 
Science: Department of Statistics and Actuarial Science
Thesis type: 
(Thesis) Ph.D.

Early evolution of a forearc basin: Georgia Basin, Vancouver Island, Canada

Author: 
Date created: 
2018-12-18
Abstract: 

The Late Cretaceous lower Nanaimo Group was deposited in the forearc Georgia Basin of BC, Canada along the western margin of the Canadian Cordillera, and records its initiation and early depositional evolution. Nanaimo Group strata are currently subdivided into 11 lithostratigraphic units, which are identified based on lithology, texture (i.e., dominantly coarse- or fine-grained), and position relative to the basal nonconformity and to one another. Paleotopography on the basal nonconformity, however, ensures that these lithostratigraphic units are not time correlative, and hence, cannot reliably be used to reconstruct basin evolution. Herein, transgressive-regressive sequence stratigraphy is employed to construct a stratigraphic framework for the lower Nanaimo Group. Eight depositional phases are identified in the lower Nanaimo Group. Depositional phases are separated by flooding surfaces, regressive surfaces, or unconformities. The stratigraphy of the lower Nanaimo Group reflects net transgression, manifested as an upwards transition from braided fluvial conglomerates through to marine mudstones.

Document type: 
Thesis
Senior supervisor: 
Shahin Dashtgard
Department: 
Science: Department of Earth Sciences
Thesis type: 
(Thesis) M.Sc.

MagnetoRheological dampers for mass and energy sensitive applications

Date created: 
2018-12-05
Abstract: 

MagnetoRheological (MR) dampers have been used as reliable electronically adjustable shock and motion control devices in the past few years. Although these dampers have proven their performance in practice and the cost has decreased, their usage has been limited to high-end applications. The main drawback of MR dampers is their relatively large weight and energy consumption when compared to their passive counterparts. In this thesis, we investigate factors affecting weight and energy consumption of MR dampers and devise solutions to achieve energy-efficient and light-weight dampers. To this end, an analytic approach is presented to design and build a low-energy consumption and lightweight MR damper. It is shown that the proposed configuration can decrease the mass of MR damper significantly and reduce the energy consumption when AlNiCo alloys are utilized in the magnetic core. A proof-of-concept MR damper for mountain bike applications is designed, fabricated, characterized, and tested in the field, which meets the requirements in mountain bike industry in terms of energy consumption, compression and rebound forces, mass, size, and on-the-fly adjustability of the damping forces, by the user.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Mehrdad Moallem
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Towards optical readout of Si:Se+

Author: 
Date created: 
2018-12-12
Abstract: 

The demonstration of a qubit system in silicon, with efficient optical control and readout of robust electronic and nuclear spin states, would change the current dominant industrial trends in quantum devices. Singly ionized deep double donors in silicon (Si:Se+) have shown promise as examples of such industry-changing qubit candidates. The (Si:Se+) system possesses a long-lived spin qubit with photonic access through a spin-selective optical transition. Under the assumption that this optical transition is radiatively efficient, it has been proposed that this optical transition be exploited for direct emission-based spin-state readout, or alternatively used as a much-sought-after silicon-integrated single-photon source. In the first part of this thesis, we present the measurement of the T1 lifetime of the optically excited state which in turn allowed us to determine a natural radiative efficiency of 0.80(1)%. Fortunately, this spin-photon interface can be coupled to photonic cavity modes for indirect spin-state read-out or to improve the emission rate through the Purcell effect. In the second part of this thesis, we present the hardware and software details of an adaptable automated photonics testing system that can be used to characterize integrated photonic devices.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Stephanie Simmons
Department: 
Science: Department of Physics
Thesis type: 
(Thesis) M.Sc.