Doctoral Theses

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The Doctoral Theses collection contains digital copies of AUT doctoral theses deposited with the Library since 2004 and made available open access. All theses for doctorates awarded from 2007 onwards are required to be deposited in Tuwhera Open Theses unless subject to an embargo.

For theses submitted prior to 2007, open access was not mandatory, so only those theses for which the author has given consent are available in Tuwhera Open Theses. Where consent for open access has not been provided, the thesis is usually recorded in the AUT Library catalogue where the full text, if available, may be accessed with an AUT password. Other people should request an Interlibrary Loan through their library.

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    The Importance of Surface Treatment of Aluminium Surface in the Context of Cost-Effective Fibre Reinforced Polymer/Metal Joint Structural Frameworks
    (Auckland University of Technology, 2023) Saniee, Ardeshir
    The joining of dissimilar materials, including metals and carbon fiber reinforced polymers (CFRPs), has emerged as a critical area of research in various advanced industries, including aerospace, automotive, electronics, and construction. This is driven by the growing demand for lightweight structures, improved performance, and enhanced functionality. The combination of aluminium and CFRP offers a unique opportunity for achieving lightweight and high-strength structures. Among the various joining techniques, adhesive bonding had garnered significant attention due to its unique advantages which can enables the formation of durable and resilient joints between aluminium and CFRP, providing good load transfer, fatigue resistance, and overall joint integrity. However, the full realisation of this potential is hindered by certain limitations and dependencies associated with adhesive bonding, specifically related to surface treatment and the challenges posed by the aluminium surface. Surface treatment plays a crucial role in enhancing the adhesion strength and durability of bonded joints. Yet, the effectiveness of surface treatments in achieving optimal bonding performance is still a subject of ongoing research. Additionally, the high level of dependency on surface characteristics, such as surface roughness and chemistry, further complicates the adhesive bonding process. In the case of aluminium and CFRP bonding, the aluminium surface presents particular challenges due to its oxide layer and modified chemical composition. These factors require careful consideration and specialised surface preparation techniques to ensure successful adhesive bonding. Addressing the limitations and dependencies of adhesive bonding for surface treatment, particularly in aluminium and CFRP bonding, is crucial to fully exploit the potential of adhesive bonding and realise its benefits in creating durable and high-performance structures. In light of these limitation and significance of surface treatment for aluminium surfaces in adhesive bonding, this study aims to provide further insights and advancement in this field. By delving into the intricate details of surface treatment techniques, including mechanical abrasion, chemical etching, and surface modification methods such as deposition of coupling agents, a comprehensive understanding of their impact on the adhesion performance both initial and exposed of the adhesively aluminium adhesively bonded joints can be gained. As a result, to investigate the influence of different set of surface treatments, both individually and in combination to each other, on the adhesion performance of the adhesively bonded joints different approaches, analytical and experimental, were conducted. For this purpose, sandpapering with mesh sizes of 240, 120 and 80, etching in diluted NaOH solution and deposition of silane, dipodal silane and zirconate were selected as the mechanical, chemical and modification methods of surface treatment, respectively, Initially, the influence of abovementioned surface treatment on different surface characteristics of the aluminium alloy, such as surface roughness parameters as well as total surface free energy and its polar and dispersive components, were investigated. Then the single lap joint and Boeing wedge test were conducted to investigate the influence of the selected surface treatment on initial and exposed performance of the adhesively bonded joints, respectively. A total of 80 treated specimens were fabricated to investigate the influence of selected surface treatment on five different surface roughness parameters, surface free energy and its polar and dispersive components and elemental composition. The polished condition of aluminium surface was selected as a benchmark in this study. The result form this study shows that etching aluminium alloy in NaOH solution can significantly alter the surface roughness parameters such as Sa and Sq of the polished aluminium surface, which was misjudged in the literature due to the lack of systematic comparison. In addition to this it was argued that the rough surface texture developed by sandpapering can enhance the effectiveness of NaOH treatment and depositing the coupling agents. First, it provides a larger surface area for NaOH treatment to react with the aluminium surface. Secondly, it can facilitate mechanical interlocking, which can favour higher adhesion between adhesive and adherend in the case of adhesive bonding. On the other hand, a total of 180 aluminium-to-aluminium bonded specimens were fabricated to study the influence of the investigated surface treatment and identify the correlation between different surface parameters and initial and exposed performance of the adhesively bonded joints. The results reveal that the NaOH treatment can significantly enhance the ultimate shear strength of adhesively bonded joints. This enhancement can be accurately predicted by the combination of surface roughness parameters Sa and Sq, as a direct relationship was observed. Furthermore, it was found that surface roughening of the aluminium alloy can indirectly affect the inital adhesion performance of the bonded joint. Specifically, roughening the aluminium surface can increase the reaction zone for NaOH treatment, thereby leading to an increase in the shear strength of the bonded joint. It was also found that the surface roughening of aluminium surface prior to NaOH treatment and coupling agent application can enhance initial adhesion performance compared to polished specimens, as observed in this study. The most significant improvement, with a 22.33% increase of ultimate shear strength, was achieved by roughening the aluminium surface with #120 grit prior to NaOH treatment, followed by zirconate deposition. This finding highlights the importance of surface preparation in achieving optimal adhesion performance in aluminium-to-aluminium bonding. Furthermore, in order to achieve the best exposed performance of the PUR adhesively bonded joint, it was found that the optimal surface roughness should be in the range of 2-2.5µm, which can be achieved through a combination of sandpapering prior to NaOH treatment and dipodal silane. It has been observed that having a high fracture toughness in dry conditions does not necessarily ensure better exposed performance of the PUR adhesively bonded joint. The fracture toughness of the PUR adhesively bonded joint decreased to 30% of its original value within the first three days of exposure time when only surface roughness was altered through manual sandpapering and NaOH treatment. This phenomenon was also observed when coupling agents were used. The study revealed that silane and dipodal silane coupling agents had better exposed performance in chamber environmental conditions compared to a zirconate coupling agent, despite having lower initial fracture toughness values.
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    Making-with Marlo: An Exploration of Cross-Species Sentience Through Nosey Means-to-an-End Props and Other Attempts
    (Auckland University of Technology, 2023) Kosovac, Ena
    Along with the project’s cocreator, Marlo (a Rottweiler), this research explores a domain of cross-species sentience. It attempts to reach across irreducible differences and access experiences that disrupt or transcend a human-centric lens. Manoeuvring within frameworks of ‘surface encounters’ and ‘sympathetic leaps,’ this practice-led project operates through a methodology of making-with cross-species. By employing a studio-based, speculative approach to art-making that includes sculpture and participatory events, the research positions the making of props as a facilitating action, enabling potential access to cross-species knowledge. Also at play, are attempts to take deeper notice of the indefinable in other beings through cocreated social intimacies and a collaborative commitment to a ‘worlding’ of mutual grounds––all mediated through sculptural props as gadgets of play and tools exploring mutual sensory borders. From these approaches, the research probes the capacity of objects to transcend the varied and shifting human signs we attach to them. It grapples with their ability to act as repositories of, or conduits towards, enigmatic cross-subjective knowledge that goes beyond accountable experience. The practice negotiates the possibility of embodied actions to bring an artwork into strange realms. It considers provisional objects as props to provoke or invite relation–– what I call means-to-an-end props––bespoke props with a nosey purpose, that being a desire to experience life as someone else. The thesis references the writings of Ron Broglio on animal phenomenology and surface encounters; Donna Haraway on companion species and collaborative assemblages; Science-fiction’s core principles and select narratives, pondering the potential of science-fictional thinking as an approach to art-making; Susan Ballard on ecological sympathies; and others. The practice finds synchronicities (and differences) with artworks involving other animals, such as works by Catherine Bagnall, Shannon Te Ao, Kalisolaite ‘Uhila, Malcolm Whittaker, Diane Borsato, Joseph Beuys, and Lucy Meyle. The research also references artists Franz Erhard Walther, Lygia Clark, Natalie Jeremijenko, Layne Waerea, Chris Braddock, Monique Redmond, Eva Koťátková, Sandy Gibbs, James Tapsell-Kururangi, and (the film) Interstellar, that explore the way props can act as conduits towards relations.
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    Transitional Acts: Suspension and Materiality in the Event
    (Auckland University of Technology, 2023) McIntosh , Jill
    The making of a new artwork emerges through potential and process within the ‘event.’ It results from a trajectory that may be interrupted or delayed, but continues moving and varying perpetually.1 Particulate and fluid matter move continuously and permeate our world. Rain falls and flows into streams; streams become rivers and run into the sea; seawater evaporates and descends again as rain. This rain nourishes trees that grow in the earth and eventually decay, feeding new seedlings. Matter has what Jane Bennett calls “vitality,”—an energy that ruptures from an event opening new possibilities and new relationships.2 Vitality and agency in material allow for complex and fluid changes in art making and this energy reveals potential, affect relations, sensation, and duration. Art is both time as it moves and time as it is held. In working with particulate matter and fluidity in this project—specifically carbon and water—I consider how continual emergent events are experienced through material change and how the suspension of material through duration and inevitability unfolds with shuddering newness. At the time of making, there is a hiatus or moment of uncertainty that is experienced as suspended movement. I conceptually map this experience onto the suspension of particles floating in a medium. As the artist immersed in the perception of this suspension, my thoughts and sensations are left hanging, unable to find stable ground, and are led by the quality of darkness and intensity of affect. By lingering in this indeterminate material state, I evoke time, change and the transience of our world. This practice-led research centres on the experiential, conceptual, and material state of suspension—on the floating, transferring, and binding of saturated material. This project finds simultaneous occurrences that are significant in relation to the practices of artists Tania Kovats, Roni Horn, Nina Canell, and Tue Greenfort in their use of elemental materials—particulate matter, water, light, and air—and their exploration of the relational interconnection with our threatened planet. Enfolded in the research are the artworks of Marie Shannon, Ralph Hotere, Lydia Ourahmane, Agnieszka Kurant and Francis Alÿs who reflect on memory, intimacy, darkness, space and continuous events in the temporality of our lives. This research is non-linear where multiple logics of reasoning and reality exist simultaneously. My methodologies of shifting and suspension respond to sensation, events, and semblance. They are situated within post-structural and post-qualitative methodologies, by exploring the complexities and the opening of questions in approaching art practice. 1 Brian Massumi, Parables for the Virtual: Movement, Affect, Sensation, (Durham and London: Duke University Press, 2002), 6. 2 Jane Bennett, Vibrant Matter: A Political Ecology of Things, (Durham and London: Duke University Press, 2010), viii.
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    Triggering Tourist Pro-environmental Behaviour Through the Priming Effect of Environmental Self-Identity
    (Auckland University of Technology, 2023) Lin, Mao-Tang
    Human actions lead to various environmental issues, such as air and water pollution and climate change. Encouraging tourists to adopt pro-environmental behaviours has received attention from researchers and policymakers because it contributes to the preservation of natural resources, reducing environmental stress. The purpose of this study is to advance the current knowledge of tourists’ pro-environmental behaviours. Specifically, this PhD research focuses on investigating the priming effect of environmental self-identity on tourists' pro-environmental behaviours. Furthermore, this research measures pro-environmental behaviours through both self-reported behaviour and actual behaviour to strengthen the validity of the research results. A systematic review of the literature shows that although environmental self-identity has been identified as a predictor of tourists' pro-environmental behaviours, how different forms of self-identities can be shaped by external cues has been overlooked. Based on self-congruity theory, the present study examines two different priming techniques to activate environmental self-identity, which in turn triggers pro-environmental behaviours. The first priming effect, which focuses on recalling past environmental behaviours, is associated with the notion of the actual self, while the second priming effect labelling individuals as proud and environmentally friendly targets their ideal self. In addition, this study identifies the mediating roles of environmental self-identity and anticipated emotions to gain a deeper understanding of tourist pro-environmental behaviours. Given that two different measures are used to manipulate environmental self-identity, this study postulates that tourists are motivated by different intrinsic emotions, namely anticipated guilt, and pride. Considering the significance of boundary conditions, this research investigates three moderators: culture (Taiwan vs. US), psychological distance (spatial distance (close vs. far) and temporal distance (short vs. long)), and choice architecture (decision mode - choice vs rejection) to confirm whether the effectiveness of the priming effects varies in different circumstances. The present study employs a quantitative methodology with an experimental design to identify the causal relationship between priming effects and pro-environmental behaviours. A series of experiments, including both laboratory experiments and quasi-experiments, are conducted for hypothesis testing. In the laboratory experiments, five different scenario-based experiments involving a total of 1695 participants evaluated the priming effects of environmental self-identity on the preference for sustainable hotels. In addition, mediators and moderators are examined in laboratory experiments. The quasi-experiment assesses recycling behaviour in a real-life setting to overcome the limitation of relying on self-reported behaviour measure. The research findings show that tourists who are primed by recalling their previous pro-environmental behaviours or are labelled as environmentally friendly have a positive influence on pro-environmental behaviours. This indicates that environmental self-identity can be shaped by external stimuli and affect subsequent pro-environmental behaviours without direct interference. Moreover, the relationship between the priming effects and pro-environmental behaviours is sequentially mediated by environmental self-identity and anticipated emotions. When primed individuals are reminded of their past pro-environmental behaviours, environmental self-identity and anticipated guilt serve as sequential mediators between the priming effect and pro-environmental behaviours. However, the priming effect of labelling people as environmentally friendly influences environmental self-identity and anticipated pride, leading to pro-environmental behaviours. The present study also identifies that culture, as a moderator, influences the relationship between priming effects and pro-environmental behaviours. Specifically, the priming effect that focuses on a person's actual self is effective in Taiwan, whereas the priming effect targeting an individual's ideal self is only significant among the participants from USA. In terms of the moderator of psychological distance, the findings reveal that the priming effect of recalling past pro-environmental behaviours is effective to elicit pro-environmental behaviour when the travel time or destination is in the near future and close proximity. On the other hand, the priming effect of identity labelling results in increased adoption of pro-environmental behaviour when the travel time or destination is more distant. Regarding the interaction between the priming effect of environmental self-identity and the choice architecture, the priming effect that recalls tourists' past pro-environmental behaviours does not vary between choice and rejection mode. However, the identity labelling technique that highlights the positive feelings associated with being an environmentally friendly person has an impact on pro-environmental behaviour in choice mode but not in rejection mode. The present study makes significant contributions to the existing literature. It is the first study to examine how priming environmental self-identity can develop actual and ideal self-congruency, leading to tourists' pro-environmental behaviours. Additionally, no previous studies have investigated whether priming effects on pro-environmental behaviours can vary by culture, psychological distance, and choice architecture. The study provides theoretical and practical implications, along with detailed recommendations for researchers and professionals in the field of tourism.
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    Heart Rate Measurement from Videos using Feed Forward Back Propagation Neural Network with Artificial Bee Colony Optimization
    (Auckland University of Technology, 2022) Kaur, Gaganjot
    The overall aim of the research reported in this thesis was to build a new non-invasive method for Heart Rate monitoring using videos and investigate the algorithms for selecting a region of interest to enable the extractions of more useful features for the measurement of Heart Rate. Analysis of these image features will assist in the creation of a more effective database for monitoring Heart Rate. Heart Rate is important for monitoring and diagnosing medical conditions of a individuals health. Several techniques are available to measure heart rate, these used sensors, which need to be in direct contact with the surface of the skin, that may cause discomfort and soreness to the patient, especially for sensitive skin patients. However, recent advances in computer vision have shown that several physiological factors linked to the heart may be evaluated without invasive methods. Heart rate monitoring can be done using video observation on the subject by analysing specific facial parts like eyes, forehead, cheeks etc. The literature has observed and shown that the facial colour changes, leading to redness from the normal face colour when the heart rate goes up. However, the changes are so minute that they cannot be observed from the naked eye, the frame responsible for detecting needs to be magnified. This research work has utilised Euler video modification as it has been cited as one of the most efficient techniques for magnifying specified portions of the face. The research was carried out by recording 30 participants, and a pulse oximeter was used to measure the heart rate. The research first extracts the frames from the input video, and then face detection is done using cascaded object detection. Then, evaluate the face's forehead using histogram equalization, magnifies it, and optimize the magnified part using Swarm Intelligence oriented Artificial Bee Colony (ABC). Modified grouping behaviour has been presented, and a novel fitness function based on the pixel distribution has been applied. Due to the shortage of samples for the training section as the global pandemic affected the entire world, the training has been done by conventional neural networks that work with Levenberg Back Propagation algorithm. The result section has been designed based on frame analysis with true-positive rate, false-positive rate, Accuracy and Kappa coefficient. The results contain the analysis based on the variation of the total number of samples in the data repository. The results compared analysis of the algorithms used in this research, Convolutional Neural Network (CNN) and Feed Forward Back Propagation (FFBPNN) with optimization method ABC and without optimization. Overall, the results compared with the proposed algorithm FFBPNN-L with ABC compared to CNN with ABC that TPR has been improved by 8.24%, Kappa coefficient has been improved by 4.58%. The limited dataset shows better results for FFBPNN-L, such that ABC with FFBPNN-L resulted in 4.25% better accuracy than ABC with CNN. Thus, FFBPNN-L with the integration of ABC shows improved results than when ABC is integrated with CNN. CNN extracts the features and does not require any external feature extraction support. This outcome with better performance of FFBPNN over CNN is mainly due to the smaller dataset size available for the research. The findings of this research, which demonstrate methodologies that can be used to monitor heart rate, also identify directions for future work in medical engineering
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