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.

Modelling the stability and maneuverability of a manual wheelchair with adjustable seating

Date created: 
2017-08-17
Abstract: 

Manual wheelchairs are generally designed with a fixed frame, which is not optimal for every situation. Spontaneous changes in seating configuration can ease transfers, increase participation in social activities, and extend reaching capabilities. These changes also shift the centre of gravity of the system, altering wheelchair dynamics. In this study, rigid body models of an adjustable manual wheelchair and test dummy were created to characterize changes to wheelchair stability and maneuverability for variations in backrest angle, seat angle, rear wheel position, user position, and user mass. Static stability was evaluated by the tip angle of the wheelchair on an adjustable slope, with maneuverability indicated by the ratio of weight on the rear wheels. Dynamic stability was assessed for the wheelchair rolling down an incline with a small bump. Both static and dynamic simulations were validated experimentally using motion capture of real wheelchair tips and falls. Overall, rear wheel position was the most influential wheelchair configuration parameter. Adjustments to the seat and backrest also had a significant impact on both static and dynamic stability. For wheelchairs with a more maneuverable (or 'tippy') initial configuration, dynamic seating changes could be used to increase stability as required.

Document type: 
Thesis
File(s): 
Example comparison of experimental and simulation dynamic stability trials
Senior supervisor: 
Carolyn Sparrey
Jaimie Borisoff
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Solving multivariate diophantine equations and their role in multivariate polynomial factorization

Date created: 
2017-08-14
Abstract: 

Multivariate polynomial factorization over integers via multivariate Hensel lifting (MHL) is one of the central areas of research in computer algebra. Most computer algebra platforms, such as Maple, Magma and Singular, implement Wang's incremental design of MHL which lifts the factors one variable at a time and one degree at a time. At each step MHL must solve a multivariate diophantine problem (MDP) which Wang solves using the same idea; lifting the solutions one variable and one degree at a time. Although this performs well when the evaluation points are mostly zero, it performs poorly when there are many non-zero evaluation points as the number of MDP problems to be solved can be exponential in the number of variables. In this thesis we introduce a new non-recursive solution to the MDP which explicitly exploits the sparsity of the solutions to the MDP. We use sparse interpolation techniques and exploit the fact that at each step of MHL, the solutions to MDP's are structurally related. We design a probabilistic sparse Hensel lifting algorithm (MTSHL) and give a complete average case complexity analysis for it. We describe a series of experiments based on our implementation of MTSHL, compare its efficiency with Wang's algorithm, and show that MTSHL performs better for many practical applications. We also show that previous probabilistic approaches proposed for MHL as an alternative to Wang's algorithm are not practical whereas MTSHL is practical and the running time is predictable.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Michael Monagan
Department: 
Science: Department of Mathematics
Thesis type: 
(Thesis) Ph.D.

Revaluing “looted” archaeological materials at Fort Apache and Theodore Roosevelt School National Historic Landmark, Arizona

Peer reviewed: 
No, item is not peer reviewed.
Date created: 
2017-07-17
Abstract: 

Between 1960 and 1978, an unauthorized collector removed thousands of artifacts from the site of this study: Fort Apache and Theodore Roosevelt School National Historic Landmark, on White Mountain Apache Tribal lands in east-central Arizona. The physical transformation of this site by a single individual caused me to consider his motives, his methods, and how heritage professionals and lawmakers define looting and looters. I address these issues by considering a series of larger questions: how do different stakeholders value heritage, how do these values change sites physically, and how does that play out in heritage management goals and practices? This study is divided into three major issues: 1) heritage values and how they can determine heritage management strategies; 2) current definitions of looting and looters; and, 3) transformation processes and how artifact collection physically impacts archaeological sites. Fort Apache is the physical focus of this study. I combine interview and field data to examine the issues above. By exploring how, why, and to what end heritage is managed at the individual, community, and state levels, I found that individual and community interests are not always represented by federal heritage legislation. I came to understand that illicit collecting could represent personal practice, rooted in concern for and interest in the artifacts themselves. My study also showed that artifacts that were illicitly collected still retained value as research data. Examining the methods and motives for, and outcomes of, illicit collecting enables a fuller understanding of the life cycle of artifacts, the extent of damage to others’ abilities to value these items, the damage done to archaeological sites, and the removal of opportunity for first-person telling of the history of a site. In addition, landscapes that have been collected from retain characteristics that reflect those collecting activities. I also considered the collector’s process as an analytical tool for understanding the meaning and means by which collectors collect. Finally, my study presents best practices for representing community interests in heritage management programs.

Document type: 
Thesis
File(s): 
Senior supervisor: 
John R. Welch
Department: 
Environment: Department of Archaeology
Thesis type: 
(Thesis) Ph.D.

The role of pathogen diversity on the evolution of resistance

Author: 
Date created: 
2017-09-21
Abstract: 

My aim is to determine whether baculovirus diversity affects the rate at which resistance evolves. Using Trichoplusia ni as a host, changes in resistance against single versus mixtures of AcMNPV variants were examined in an evolution experiment. AcMNPV variants were isolated using dilution cloning and characterized using RFLP and pathogenicity bioassay. I found that the rate of evolution of resistance to more diverse pathogen infections to be less than that of single variants and the level of resistance was reduced by over 284-fold compared to specific single variants. Identity of the single variants had a major influence on the rate of evolution of resistance. Additionally, I found evidence of higher fitness costs of resistance to more diverse infections. My findings indicate that pathogen diversity should be factored into resistance management strategies for microbial insecticides and provide insight into the role of pathogen diversity on the evolution of resistance to pathogens.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jenny Cory
Department: 
Science: Biological Sciences Department
Thesis type: 
(Thesis) M.Sc.

Characterization of signaling pathways enabling coordinated morphogenesis of tissues during Drosophila dorsal closure

Author: 
Date created: 
2017-06-30
Abstract: 

Drosophila dorsal closure (DC) is the best-characterized model system for studying wound healing. During DC, a hole in the dorsal epidermis, covered by an epithelium called the amnioserosa (AS), is sealed by migration of the epidermal flanks. Seamless closure is achieved through coordinated morphogenesis of the AS and epidermis, which is facilitated by communication between the two tissues via bidirectional signaling networks. To better understand this crosstalk, three diffusible signals present during DC were analyzed, and their signaling roles were identified: 1.) Folded gastrulation (Fog), which may act as an upstream activator of a JNK pathway in the epidermis; 2.) the TGF-β ligand, Decapentaplegic (Dpp), which regulates production of the steroid hormone, 20- hydroxyecdysone (ecdysone) in the AS; 3.) ecdysone, which interacts with the transcription factor AP-1 to regulate gene transcription in the AS. Signaling via these molecules ultimately regulates myosin contractility necessary for morphogenesis of both tissues during DC.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Nicholas Harden
Department: 
Science: Department of Molecular Biology and Biochemistry
Thesis type: 
(Thesis) M.Sc.

Archaeologists and Indigenous Traditional Knowledge in British Columbia

Date created: 
2017-07-21
Abstract: 

Archaeologists who study the past histories and lifeways of Indigenous cultures have long used Indigenous traditional knowledge as a source of historical information. Initially, archaeologists primarily accessed traditional knowledge second-hand, attempting to extract historical data from ethnographic sources. However, as archaeologists increasingly work with (and sometimes for) Indigenous communities, they have the opportunity to access traditional knowledge directly. Traditional knowledge is a powerful resource for archaeology, but working with it raises significant socio-political issues. Additionally, integrating traditional knowledge with archaeology’s interpretive frameworks can present methodological and epistemological challenges.This thesis examines the implications of archaeologists’ engagement with traditional knowledge in British Columbia, Canada, where changes at both a disciplinary and broader societal level indicate that archaeologists will increasingly need to find effective and ethical ways to work with traditional knowledge (and knowledge-holders). Through a series of in-depth interviews with practicing archaeologists from around the province, I explore how personal histories, professional circumstances, social realities, and theoretical frameworks affect how traditional knowledge is used in British Columbian archaeology. I conclude by highlighting five emergent interview themes: 1) the significance of personal background and social context in determining how researchers approach traditional knowledge; 2) the importance of long-term relationships between archaeologists and individual First Nations communities; 3) the value of traditional knowledge for illuminating more “ephemeral” aspects of the past; 4) the need for researchers to develop regionally and culturally specific understandings of traditional knowledge in order to work with it responsibly; and 5) the tension between studying Indigenous epistemologies and incorporating them into archaeological interpretations.

Document type: 
Thesis
File(s): 
Senior supervisor: 
George Nicholas
Department: 
Environment: Department of Archaeology
Thesis type: 
(Thesis) M.A.

The Multiplicative Assignment Problem

Author: 
Date created: 
2017-07-06
Abstract: 

The quadratic assignment problem (QAP) is an extensively studied combinatorial optimization problem. The special case of QAP where the cost matrix is of rank one is called the multiplicative assignment problem (MAP). MAP is not well studied in literature, particularly in terms of experimental analysis of algorithms. In this thesis we present some mixed integer linear programming formulations and compare their selective strength using experimental analysis. We also present exact and heuristic algorithms to solve MAP. Our heuristic algorithms include improvements in existing FPTAs, as well as local search and tabu search enhancements. Results of extensive experimental analyses are also reported.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Abraham Punnen
Department: 
Science: Department of Mathematics
Thesis type: 
(Thesis) M.Sc.

The effects of auditory, visual, and gestural information on the perception on Mandarin tones

Date created: 
2017-08-04
Abstract: 

In multimodal speech perception, strategic connections between auditory and visual- spatial events can aid in the disambiguation of speech sounds. This study examines how co-speech hand gestures mimicking pitch contours in space affect non-native Mandarin tone perception. Native English as well as Mandarin perceivers identified tones with either congruent (C) or incongruent (I) Audio+Face (AF) and Audio+Face+Gesture (AFG) input. Mandarin perceivers performed at ceiling rates in the Congruent conditions, but showed a partially gesture-based response in AFG-I, revealing that gestures were perceived as valid cues for tone. The English group’s performance was better in congruent than incongruent AF and AFG conditions. Their identification rates were also highly skewed towards the visual tone when gesture was presented in the AFG compared to AF conditions. These results indicate positive effects of facial and especially gestural input on non-native tone perception, suggesting that crossmodal resources can be recruited to aid auditory perception when phonetic demands are high.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Yue Wang
Department: 
Arts & Social Sciences: Department of Linguistics
Thesis type: 
(Thesis) M.A.

Observations and Reflections: Made in the Course of a Journey through France and Italy 1786-1787, by Lady Aphrodite Macbain

Date created: 
2017-07-17
Abstract: 

This paper is an historical fiction-- a travel journal written by Lady Aphrodite Macbain, an aristocratic English woman who records her observations and thoughts during her European tour in 1786-1787. Three voices tell this tale: Lady Aphrodite Macbain, a twenty-first century editor, Elizabeth Macbain, and the author of this text, Elizabeth Kidd. Elizabeth Macbain introduces the "found" journal, provides a biography of Lady Macbain and inserts historical background information on the eighteenth century, while Elizabeth Kidd (E.K.) provides background information on the cities visited, critical commentary and explanatory footnotes to the text. Included in the journal are the author's own botanical illustrations.Three primary issues relating to the eighteenth century will be addressed: the changing role of women in European society; the emerging interest in botanical sciences, and the role of the Grand Tour in promoting social change. Experiences of three main characters, Lady Macbain, her brother Andrew and her niece Belinda, offer opportunities to explore these issues from different perspectives.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Stephen Duguid
Betty Schellenberg
Department: 
Arts & Social Sciences: Liberal Studies Program
Thesis type: 
(Project) M.A.L.S.

CVE Programs and Initiatives through the Ages: A snapshot of the past, present, and future

Date created: 
2017-08-03
Abstract: 

We have now reached the stage where there are many countering violent extremism (CVE) programs and initiatives in existence. Each program leaves a unique imprint, making it possible to trace these efforts through the ages, as well as give some indication as to what is working and not working. An extensive literature review surveying academic publications and independent/government reports regarding radicalization theory, and more specifically, deradicalization, disengagement, rehabilitation, and prevention efforts is used to build the framework for this study’s database. A content analysis utilizing data triangulation is then conducted on 67 existing or previously existing CVE programs/initiatives. The Information drawn from these programs is used to develop a timeline of where CVE efforts have been, where they are now, and provides an idea of where they might be going. Some impressions made by these efforts have been marked – good and bad, lending pertinent information to the development of these types of programs. This study is intended to inform and improve the next generation of CVE programming.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Garth Davies
Department: 
Arts & Social Sciences: School of Criminology
Thesis type: 
(Thesis) M.A.