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Electronic Theses and Dissertations (ETD) Repository This section preserves Master's theses and doctoral dissertations accepted at Laurentian University and is a mechanism for making this form of scholarly work widely accessible.

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Access status: Open Access ,
Semi-autonomous computer vision-based rockbreaker
(Laurentian University Library & Archives, 2021-01-27) Aslanzadeh, Reza; Dr. Amr Abdel-Dayem
Automating rockbreaker manipulation improves the safety and performance of mining site operations. The goal of this project is to design and develop a semi-autonomous rockbreaker. This research contributed to both the industrial and scientific aspects of this problem. For the industrial part, we implemented a complete semi-autonomous rockbreaker’s chain. Our proposed system will solve teleportation challenges. Also, it will fulfill some of the requirements of a fully autonomous rockbreaker. Besides, it can be used for future research toward a final fully autonomous rockbreaker. We proposed a heuristic path planner algorithm that can compete with a trained operator in terms of both speed and accuracy of reaching the target position. For the scientific part, we proposed a camera-based arm tracking algorithm that overcomes the shortcomings of the current non-camera-based approach. Moreover, it decreases both installation and maintenance costs. Furthermore, it is more stable than the current approach as well. Using our industrial product, we suggested a method to automatically generate labelled data to train our camera-based arm tracking method.
Access status: Open Access ,
Correlation of breast cancer biology and x-ray scatter data
(Laurentian University Library & Archives, 2022-08-24) Pasricha, Prarthana; Dr. Robert Leclair, Dr. Dean Millar
Wide angle x-ray scatter (WAXS) imaging can potentially be used to diagnose ductal carcinoma in situ (DCIS) in breast biopsies. In this work, WAXS signals are used to model healthy and diseased breast tissue. It is accomplished by analysis of the breast tissue’s differential linear scattering coefficients ‘μₛ’. The tissue samples are assumed to consist of varying amount of fat, stroma and cells and their μₛ coefficients can be expressed by the following sum: μₛ(x) = afat • μₛ fat(x) + astr •μₛ str(x) + acell •μₛ cell(x), where x= (1/ λ) sin(θ/2) is the momentum transfer argument, λ is the x-ray wavelength and θ is the scatter angle. Data for breast tissues was taken from literature and that for stroma was estimated using histology studies. The fractional volumes of each of the three components (afat, astr, acell) were evaluated using singular value decomposition (SVD). Fitting results suggest cancer consists of 44% cells as compared to only 8% and 7% for normal and benign tissue, respectively. These results support the argument that an uncontrolled proliferation of cells is the hallmark of cancer. The fat decreases from 56% (normal) to 26% (benign) and to only 3.4% in cancer. This is justified by the fact that invasive ductal carcinoma cells use fat to fuel their growth and spread. Stromal increase from 35% in normal to 67% in benign suggest that benign diseases such as fibroadenoma are characterized by a surge in fibrous tissue. The model predictions of the compositions for normal, benign and malignant tissue are promising. It gives insight into how cancer interacts with its microenvironment. While scatter studies on cells and fat have been done in the past, not much is known about stroma in the same context. Studies show that stroma promotes cancer growth and metastasis, making it an important component to focus on. The second part of this research works on this aspect. A model for stroma made up of 80% collagen, 10% elastin and 10% versican is introduced. μs for stroma is then determined using Independent Atomic Model (IAM) approximation. The scattersignal obtained via this newly introduced stroma model matches with the previous estimation, mainly at the higher values of momentum transfer values. This is because IAM fails at the lower regime due to interference phenomenon. It is observed that the scatter values obtained using IAM are not very sensitive to the change in composition of stroma. In most of the cases, the percentage change with reference to the original model is less than 1%. In the event in which elastin is considered to be the major constituent, a difference of 2.41% to 3.49% is seen. This model gives important information about the structure and function of stroma and highlights its role in cancer progression.
Access status: Open Access ,
The role of personal projects in the relationship between job fit and satisfaction
(Laurentian University Library & Archives, 2022-08-22) Colton, Sarah; Dr. Josée Turcotte, Dr. Bruce Oddson
One of the most common measures of employee well-being is job satisfaction. Person-job fit, the degree to which an individual perceives their fit to their job, is one of the strongest known predictors of job satisfaction. However, the idea of fit does not necessarily capture whether a job fulfills one's requirements for a meaningful life. Under Free Trait Theory, people can act in ways that do not fit their personality when situations are sufficiently important. One characterization that may determine a situation's importance is its relevance to an individual's projects. This suggests that person-job fit could be potentially less relevant to satisfaction when their job satisfies the needs of their personal projects. The present study investigated the role of work- related personal projects in the relationship between job fit and satisfaction. Participants (n=195) were asked about their perceived person-job fit (Person-Job Fit Scale), job satisfaction (Minnesota Satisfaction Questionnaire), and personal projects (Little's personal project analysis methodology) for their current (or most recent job) and for one previous job. Most participants reported having work-related personal projects that were important to them. There was a strong positive relationship between person-job fit and job satisfaction for both current (or most recent) jobs (r=.71) and for previous jobs (r=.60). The importance and the number of work-related personal projects did not contribute to predictions of job satisfaction. They did not moderate the relationship between person-job fit and job satisfaction. These results contribute to the literature on job fit and satisfaction. Specifically, they suggest that any contribution of personal projects to job satisfaction was, in fact, relatively stable across a variety of job situations and people.
Access status: Open Access ,
The Åkulla volcanic-hosted Au-Te deposit, Skellefte District, Sweden : characterization of host rocks, alteration and mineralization
(Laurentian University Library & Archives, 2025-04-29) Nordfeldt, Paulina; Dr. Harold Gibson, Dr. Iain Pitcairn
The Åkulla Au-Te deposit is located in the Skellefte District (SD), Northern Sweden, a worldclass mineral district with abundant volcanic massive sulphide (VMS) deposits. The Åkulla Au-Te deposit is one of 4 active mines in SD. The deposit has produced and currently contains 11.8 Mt of ore grading 4.1 g/t Au, 7.7 g/t Ag, 150.0 g/t Te, 89.7 g/t Bi and 1.0 wt% S since production started in 2012. The Åkulla Au-Te deposit is hosted by an upward-pointing, irregular lens shaped body of strongly altered coherent dacites, andesites and breccias, oriented sub-parallel to the steeply dipping volcanic strata. The hydrothermal alteration is strongly zoned with a quartztopaz±sericite±andalusite core, surrounded by sericite-quartz ± chlorite ± andalusite ± base metal sulfide association with minor occurrences of corundum in sericite-chlorite rock, followed outwards by sericite ± andalusite ± base metal sulfides and chlorite ±base metal sulfides associations. The outer sulfide-bearing alteration zones continue to surface to the small Åkulla Östra semi-massive VMS deposit, which was mined as an open pit. The mineralization and host rocks have been metamorphosed to upper greenschist facies and are flattered and elongated subparallel to the D2 foliation and lineation, indicating their formation pre-deformation. The Åkulla Au-Te deposit differs from other VMS deposits in SD by being sulphide poor (<3%), and native gold and telluride enriched. The four main breccia facies that host the deposit formed through synvolcanic quench brecciation and subsequent synvolcanic hydrothermal brecciation. The occurrence and variations of quartz and topaz alteration within coherent units, breccia clasts and matrices indicate that the rocks were altered before and during brecciation. The near vertical orientation of the graded beds in mass flow deposits is a product of block rotation during synvolcanic extension and subsequent deformation (Paper I). Alteration mineral- and elemental-zoning show a strong correlation. Au and Te enrichments are found in almost every alteration zone. However, the quartz and topaz dominant core is strongly depleted in major, chalcophile and some HFS elements, but enriched in Si, Ag, Bi, Sb and Mo. Corundum occurrences correlate with Si depletion and Al, Ti, Zr, Nb enrichment. Above and irregularly surrounding the central core, a zone of Fe, S, Cu, Zn, Ni and Pb enrichment occurs (Paper III). This distinct pattern reflects a systematic change in the bulk composition of the host rocks due to interaction with a hot and acidic fluid in the core, to progressively lower temperatures and reduced acidity fluids towards the margins. Hydrothermal alteration conditions based on an interpreted synvolcanic formation of topaz and corundum (Paper II) in addition to the elemental zoning suggest a core of relatively low pH (2-4) and temperatures ≥400°C, decreasing to around 375°C in the corundum bearing zone to an outer, near neutral pH and lower temperature (<250°C) zone (Paper II-III). The Åkulla Au-Te deposit is interpreted as a synvolcanic magmatic-hydrothermal deposit that formed at or near the seafloor. The relationship between brecciation and alteration, the abundance of F-rich topaz, the zonation of alteration minerals and elements suggest that an acidic, high temperature, F-rich fluid most likely of magmatic-hydrothermal origin was responsible for the brecciation, alteration and mineralization. The Åkulla Au-Te deposit represents a magmatic end-member style of VMS deposit in the SD. The distinct hydrothermal alteration conditions and mineralization styles at the Åkulla Au-Te deposit have implications for exploration models in the SD and other VMS districts.
Access status: Open Access ,
Étude du développement de la pensée critique chez les élèves de l’élémentaire issus de la première génération d’immigrants africains : points de vue des enseignants et enseignantes de l’Ontario
(Laurentian University Library & Archives, 2025-10-03) Kra, Edwige Amoin Anicette
Cette recherche doctorale s’intéresse au développement de la pensée critique chez les élèves de l’élémentaire issus de la première génération d’immigrants africains dans le système éducatif ontarien. Dans un contexte marqué par la diversité culturelle, elle explore les mécanismes didactico-pédagogiques mobilisés par les enseignant.e.s pour favoriser cette compétence essentielle, reconnue pour son rôle transversal dans la réussite scolaire et la préparation à la citoyenneté active. Inscrite dans une posture épistémologique herméneutique, l’étude adopte une approche qualitative pour interroger les conceptions, les stratégies pédagogiques et la prise en compte de la culture des élèves dans les mécanismes de développement de la pensée critique. Les résultats révèlent une pluralité de conceptions de la pensée critique, oscillant entre une approche psychopédagogique, centrée sur le développement progressif de compétences, et une approche philosophique, fondée sur le questionnement et le jugement éclairé. Les stratégies pédagogiques identifiées s’inscrivent dans une logique active et pédocentrique, où l’élève est considéré comme un acteur réflexif et autonome de son apprentissage. Cette approche vise le développement global de l’enfant, en tenant compte de ses besoins, intérêts et rythmes d’évolution. Cependant, l’étude met en lumière une prise en compte encore marginale du facteur culturel dans l’enseignement de la pensée critique. Les pratiques observées demeurent souvent génériques et peu contextualisées aux réalités des élèves immigrants africains, ce qui peut limiter leur accès à une pensée critique authentique. En s’appuyant sur une perspective sociologique et interculturelle, la recherche souligne l’importance de valoriser les parcours migratoires et les ressources cognitives des élèves issus de la diversité. Enfin, cette étude propose des pistes pour de futures recherches, notamment l’observation directe des pratiques en classe, l’exploration du point de vue des élèves, et le développement d’outils didactiques contextualisés. Elle plaide pour une éducation inclusive et équitable, capable de promouvoir une véritable justice cognitive et de faire de l’école un lieu d’émancipation intellectuelle.