Design and optimisation of the limaçon rotary compressor
- Lu, Kui
- Authors: Lu, Kui
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The limaçon positive displacement machine is characterised by its internal geometry and unique mechanical motion; both based on a mathematical curve known as the limaçon of Pascal. The limaçon technology offers many advantages, such as compact size and double‐acting functionality, and its great potential for fluid processing applications has been proven by a number of patents and innovative designs in engines, expanders, and pumps. However, no commercial application of the limaçon technology in the field of positive displacement compressors has been reported in the literature. This could be attributed to the fact that the potential of the limaçon technology for gas compression has not been established as yet. The process of establishing potential is necessary before funds and resources are dedicated to investing in prototyping and testing. This process entails a considerable amount of modelling, coding and analysis as one must ensure the embodiment is geometrically capable of delivering suction and compression strokes, ports can be arranged to support the workings of these strokes, a number of measurable parameters can be identified as impacting compressor performance and it is possible to calculate a set of parameters which optimise this performance. To achieve this objective, a comprehensive mathematical model of a limaçon machine, implemented as a compressor,was first developed. The model, which is multi‐physical in nature, spans such domains as kinematics, fluid dynamics, characteristics of the port flow, internal leakage due to seal vibration, dynamics of the discharge valve, and thermodynamics. Subsequently, the simulation of the model has been performed to numerically study the operational characteristics of the limaçon compressor and to investigate the effect of various parameters on the compressor performance. It was found that the increase in the operating speed and pressure ratio would lead to negative effects on machine performance, especially on volumetric efficiency. Additionally, the results of simulations indicated that the level of fluid over‐compression is influenced by the characteristics of the discharge valve. To ensure the suitability of limaçon technology for use in positive displacement compressors, a study was undertaken to determine whether such an embodiment lent itself to optimisation efforts. For this purpose, the thorough mathematical model which has been developed to simulate compressor workings was then used for optimisation purposes whereby a Bayesian optimisation procedure was applied. The optimisation procedure was conducted in a two‐stage fashion where the first stage optimises the machine dimensions to meet volumetric requirements specified by the designer; and the second stage focuses on revealing the optimum combination of port geometries that improves machine performance. A numerical illustration was presented to prove the validity of the presented approach, and the results show that considerable improvements in the isentropic and volumetric efficiencies can be attained. Moreover, the optimised design was tested under different operating speeds and pressure ratios to investigate its robustness. It was found that the optimised design can exhibit relatively stable performance when the working conditions vary within a small bandwidth around that used in the optimisation procedure. The limaçon technology has three embodiments, namely the limaçon‐to‐limaçon (L2L), the limaçon‐to‐circular, and the circolimaçon. The circolimaçon embodiment features using circular arcs, rather than limaçon curves, to develop profiles for the rotor and housing. This embodiment simplifies the manufacturing process and reduces the production cost associated with producing a limaçon technology. A feasibility study of the circolimaçon embodiment was conducted by comparing its performance with that of the L2L type device. The machine dimensions and port geometries obtained from the optimisation procedure were used in the comparative study. A nonlinear three‐degree of freedom model was presented to describe the dynamic behaviour of the apex seal during the machine operation. Additionally, the leakage through the seal‐housing gap was formulated by considering the inertia and viscous effects of the flow. The results from the case study suggest that the circolimaçon embodiment exhibits comparable performance to the L2L‐type machine, despite having more significant seal vibrations. Moreover, it was also discovered that the circolimaçon compressor with a small capacity undergoes a lower level of seal dynamics, indicating better machine reliability.
- Description: Doctor of Philosophy
- Authors: Lu, Kui
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The limaçon positive displacement machine is characterised by its internal geometry and unique mechanical motion; both based on a mathematical curve known as the limaçon of Pascal. The limaçon technology offers many advantages, such as compact size and double‐acting functionality, and its great potential for fluid processing applications has been proven by a number of patents and innovative designs in engines, expanders, and pumps. However, no commercial application of the limaçon technology in the field of positive displacement compressors has been reported in the literature. This could be attributed to the fact that the potential of the limaçon technology for gas compression has not been established as yet. The process of establishing potential is necessary before funds and resources are dedicated to investing in prototyping and testing. This process entails a considerable amount of modelling, coding and analysis as one must ensure the embodiment is geometrically capable of delivering suction and compression strokes, ports can be arranged to support the workings of these strokes, a number of measurable parameters can be identified as impacting compressor performance and it is possible to calculate a set of parameters which optimise this performance. To achieve this objective, a comprehensive mathematical model of a limaçon machine, implemented as a compressor,was first developed. The model, which is multi‐physical in nature, spans such domains as kinematics, fluid dynamics, characteristics of the port flow, internal leakage due to seal vibration, dynamics of the discharge valve, and thermodynamics. Subsequently, the simulation of the model has been performed to numerically study the operational characteristics of the limaçon compressor and to investigate the effect of various parameters on the compressor performance. It was found that the increase in the operating speed and pressure ratio would lead to negative effects on machine performance, especially on volumetric efficiency. Additionally, the results of simulations indicated that the level of fluid over‐compression is influenced by the characteristics of the discharge valve. To ensure the suitability of limaçon technology for use in positive displacement compressors, a study was undertaken to determine whether such an embodiment lent itself to optimisation efforts. For this purpose, the thorough mathematical model which has been developed to simulate compressor workings was then used for optimisation purposes whereby a Bayesian optimisation procedure was applied. The optimisation procedure was conducted in a two‐stage fashion where the first stage optimises the machine dimensions to meet volumetric requirements specified by the designer; and the second stage focuses on revealing the optimum combination of port geometries that improves machine performance. A numerical illustration was presented to prove the validity of the presented approach, and the results show that considerable improvements in the isentropic and volumetric efficiencies can be attained. Moreover, the optimised design was tested under different operating speeds and pressure ratios to investigate its robustness. It was found that the optimised design can exhibit relatively stable performance when the working conditions vary within a small bandwidth around that used in the optimisation procedure. The limaçon technology has three embodiments, namely the limaçon‐to‐limaçon (L2L), the limaçon‐to‐circular, and the circolimaçon. The circolimaçon embodiment features using circular arcs, rather than limaçon curves, to develop profiles for the rotor and housing. This embodiment simplifies the manufacturing process and reduces the production cost associated with producing a limaçon technology. A feasibility study of the circolimaçon embodiment was conducted by comparing its performance with that of the L2L type device. The machine dimensions and port geometries obtained from the optimisation procedure were used in the comparative study. A nonlinear three‐degree of freedom model was presented to describe the dynamic behaviour of the apex seal during the machine operation. Additionally, the leakage through the seal‐housing gap was formulated by considering the inertia and viscous effects of the flow. The results from the case study suggest that the circolimaçon embodiment exhibits comparable performance to the L2L‐type machine, despite having more significant seal vibrations. Moreover, it was also discovered that the circolimaçon compressor with a small capacity undergoes a lower level of seal dynamics, indicating better machine reliability.
- Description: Doctor of Philosophy
Ecology and management of a tropical invasive weed, Cyperus aromaticus (Navua sedge) in Queensland, Australia
- Authors: Chadha, Aakansha
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Cyperus aromaticus (Ridley) Mattf. & Kükenth, commonly known as Navua sedge is an invasive C4 perennial sedge species of the Cyperaceae family found predominantly in tropical environments. A native of tropical Africa, it has spread widely and become problematic in many southwest Pacific islands and in tropical north Queensland, Australia. It is a principal weed infesting pastures, sugarcane, banana and root crops, which causes significant damage across a range of industries including dairy, beef, sugarcane and banana in the highly fertile and productive areas of Queensland. The primary objective of this thesis was to contribute to a significant weed management problem at a stage where intervention is cost effective, efficient and environmentally sensitive. At the centre of this work, was a contribution to fundamental knowledge regarding the ecology of the species. The first objective was to examine the global literature on rhizomatous weeds and C. aromaticus in particular to identify the research problems and knowledge gaps. As C. aromaticus has dual mode of reproduction, via seeds and rhizomes, both these aspects were taken into consideration in the experimental chapters. The project critically addressed the issues related to (i) understanding the fundamental ecological aspects of reproduction via seeds in C. aromaticus, (ii) the regeneration of C. aromaticus from its rhizomes, and (iii) control of C. aromaticus using herbicides. A stepwise approach, involving multiple objectives was used to meet the primary objective of this project. Three experiments were conducted to understand the fundamental ecological aspects of reproduction via seeds. (i) A study was conducted to understand the soil seed bank dynamics of pastures invaded by C. aromaticus. It was found that C. aromaticus is the dominant species in the soil seed bank of pastures invaded by C. aromaticus and can contribute between 62% and 95% of the total seed bank. In this respect, the abundance of C. aromaticus seed in the soil seed bank is positively correlated with the aboveground biomass of C. aromaticus and 83% of the total C. aromaticus seeds was found in the top 0-5 cm layer of soil. (ii) The lifespan of C. aromaticus seeds was estimated by artificial ageing technique in the laboratory whereby the results indicate that long-term management is required to control the recruitment from the soil seed bank even in the absence of additional seed deposition. (iii) Seed germination ecology was investigated to understand the effect of various environmental factors on the germination of C. aromaticus seeds. It was found that light is absolutely required for C. aromaticus seed germination, and there was no germination of seeds above 150 mM NaCl concentration and -0.8 Mpa osmotic potential, or from seeds buried greater than 2 cm below the soil surface. Focussing on the regeneration from C. aromaticus rhizomes, an experiment was conducted to investigate the effect of rhizome size and burial depth on the emergence from rhizomes in different soil types. A positive correlation was found between the total emergence of tillers and rhizome fragment size of C. aromaticus, but a negative correlation was found between the total emergence of tillers and burial depth of rhizomes. Importantly, it was also found that rhizomes when reduced to 10 cm or smaller fragments and buried 15 cm or deeper will prevent emergence. A further two glasshouse experiments were conducted to explore chemical options to control both the aboveground biomass and the belowground rhizomes. (i) The herbicide sensitivity of various rates of halosulfuron-methyl was evaluated at different growth stages using plants with and without established rhizomes. Mortality of 27.5%, 0% and 5% was recorded when treated with 75 g ai ha-1 of halosulfuron-methyl at the mowed, pre-flowering and flowering stages, respectively in plants with established rhizomes. The herbicide was effective in controlling the aboveground growth, however, subsequent emergence of new growth from the rhizome confirms the failure of the herbicide to kill the rhizome. In contrast, application of 75 g ai ha-1 of halosulfuron-methyl provided 100% mortality in plants treated at seedling and pre-flowering stage in plants without established rhizomes. (ii) Another herbicide with an alternate mode of action, florpyrauxifen-benzyl, was assessed at different growth stages again using plants with and without established rhizomes. Results indicate that a single application of florpyrauxifen-benzyl is effective at controlling C. aromaticus seedlings, but not effective at controlling plants with established rhizomes. In summary, this thesis has increased the fundamental knowledge about the ecology of C. aromaticus which will feed into designing of management strategies. Likewise, new tools established in the form of mechanical and chemical control and improving the methods currently used to manage populations will advance the capacity to effectively manage C. aromaticus in the future. Although this investigation is based on a relatively focussed suite of issues relevant to tropical north Queensland, where there is an immediate application of the research outcomes from this study, it is anticipated that they will also inform weed management strategies more broadly in a range of similar environments throughout the world.
- Description: Doctor of Philosophy
- Authors: Chadha, Aakansha
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Cyperus aromaticus (Ridley) Mattf. & Kükenth, commonly known as Navua sedge is an invasive C4 perennial sedge species of the Cyperaceae family found predominantly in tropical environments. A native of tropical Africa, it has spread widely and become problematic in many southwest Pacific islands and in tropical north Queensland, Australia. It is a principal weed infesting pastures, sugarcane, banana and root crops, which causes significant damage across a range of industries including dairy, beef, sugarcane and banana in the highly fertile and productive areas of Queensland. The primary objective of this thesis was to contribute to a significant weed management problem at a stage where intervention is cost effective, efficient and environmentally sensitive. At the centre of this work, was a contribution to fundamental knowledge regarding the ecology of the species. The first objective was to examine the global literature on rhizomatous weeds and C. aromaticus in particular to identify the research problems and knowledge gaps. As C. aromaticus has dual mode of reproduction, via seeds and rhizomes, both these aspects were taken into consideration in the experimental chapters. The project critically addressed the issues related to (i) understanding the fundamental ecological aspects of reproduction via seeds in C. aromaticus, (ii) the regeneration of C. aromaticus from its rhizomes, and (iii) control of C. aromaticus using herbicides. A stepwise approach, involving multiple objectives was used to meet the primary objective of this project. Three experiments were conducted to understand the fundamental ecological aspects of reproduction via seeds. (i) A study was conducted to understand the soil seed bank dynamics of pastures invaded by C. aromaticus. It was found that C. aromaticus is the dominant species in the soil seed bank of pastures invaded by C. aromaticus and can contribute between 62% and 95% of the total seed bank. In this respect, the abundance of C. aromaticus seed in the soil seed bank is positively correlated with the aboveground biomass of C. aromaticus and 83% of the total C. aromaticus seeds was found in the top 0-5 cm layer of soil. (ii) The lifespan of C. aromaticus seeds was estimated by artificial ageing technique in the laboratory whereby the results indicate that long-term management is required to control the recruitment from the soil seed bank even in the absence of additional seed deposition. (iii) Seed germination ecology was investigated to understand the effect of various environmental factors on the germination of C. aromaticus seeds. It was found that light is absolutely required for C. aromaticus seed germination, and there was no germination of seeds above 150 mM NaCl concentration and -0.8 Mpa osmotic potential, or from seeds buried greater than 2 cm below the soil surface. Focussing on the regeneration from C. aromaticus rhizomes, an experiment was conducted to investigate the effect of rhizome size and burial depth on the emergence from rhizomes in different soil types. A positive correlation was found between the total emergence of tillers and rhizome fragment size of C. aromaticus, but a negative correlation was found between the total emergence of tillers and burial depth of rhizomes. Importantly, it was also found that rhizomes when reduced to 10 cm or smaller fragments and buried 15 cm or deeper will prevent emergence. A further two glasshouse experiments were conducted to explore chemical options to control both the aboveground biomass and the belowground rhizomes. (i) The herbicide sensitivity of various rates of halosulfuron-methyl was evaluated at different growth stages using plants with and without established rhizomes. Mortality of 27.5%, 0% and 5% was recorded when treated with 75 g ai ha-1 of halosulfuron-methyl at the mowed, pre-flowering and flowering stages, respectively in plants with established rhizomes. The herbicide was effective in controlling the aboveground growth, however, subsequent emergence of new growth from the rhizome confirms the failure of the herbicide to kill the rhizome. In contrast, application of 75 g ai ha-1 of halosulfuron-methyl provided 100% mortality in plants treated at seedling and pre-flowering stage in plants without established rhizomes. (ii) Another herbicide with an alternate mode of action, florpyrauxifen-benzyl, was assessed at different growth stages again using plants with and without established rhizomes. Results indicate that a single application of florpyrauxifen-benzyl is effective at controlling C. aromaticus seedlings, but not effective at controlling plants with established rhizomes. In summary, this thesis has increased the fundamental knowledge about the ecology of C. aromaticus which will feed into designing of management strategies. Likewise, new tools established in the form of mechanical and chemical control and improving the methods currently used to manage populations will advance the capacity to effectively manage C. aromaticus in the future. Although this investigation is based on a relatively focussed suite of issues relevant to tropical north Queensland, where there is an immediate application of the research outcomes from this study, it is anticipated that they will also inform weed management strategies more broadly in a range of similar environments throughout the world.
- Description: Doctor of Philosophy
Efficient texture descriptors for image segmentation
- Authors: Tania, Sheikh
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Colour and texture are the most common features used in image processing and computer vision applications. Unlike colour, a local texture descriptor needs to express the unique variation pattern in the intensity differences of pixels in the neighbourhood of the pixel-of-interest (POI) so that it can sufficiently discriminate different textures. Since the descriptor needs spatial manipulation of all pixels in the neighbourhood of the POI, approximation of texture impacts not only the computational cost but also the performance of the applications. In this thesis, we aim to develop novel texture descriptors, especially for hierarchical image segmentation techniques that have recently gained popularity for their wide range of applications in medical imaging, video surveillance, autonomous navigation, and computer vision in general. To pursue the aim, we focus in reducing the length of the texture feature and directly modelling the distribution of intensity-variation in the parametric space of a probability density function (pdf). In the first contributory chapter, we enhance the state-of-the-art Weber local descriptor (WLD) by considering the mean value of neighbouring pixel intensities along radial directions instead of sampling pixels at three scales. Consequently, the proposed descriptor, named Radial Mean WLD (RM-WLD), is three-fold shorter than WLD and it performs slightly better than WLD in hierarchical image segmentation. The statistical distributions of pixel intensities in different image regions are diverse by nature. In the second contributory chapter, we propose a novel texture feature, called ‘joint scale,’ by directly modelling the probability distribution of intensity differences. The Weibull distribution, one of the extreme value distributions, is selected for this purpose as it can represent a wide range of probability distributions with a couple of parameters. In addition, gradient orientation feature is calculated from all pixels in the neighbourhood with an extended Sobel operator, instead of using only the vertical and horizontal neighbours as considered in WLD. The length of the texture descriptor combining joint scale and gradiet orientation features remains the same as RM-WLD, but it exhibits significantly improved discrimination capability for better image segmentation. Initial regions in hierarchical segmentation play an important role in approximating texture features. Traditional arbitrary-shaped initial regions maintain the uniform colour property and thus may not retain the texture pattern of the segment they belong to. In the final contributory chapter, we introduce regular-shaped initial regions by enhancing the cuboidal partitioning technique, which has recently gained popularity in image/video coding research. Since the regions (cuboids) of cuboidal partitioning are of rectangular shape, they do not follow the colour-based boundary adherence of traditional initial regions. Consequently, the cuboids retain sufficient texture pattern cues to provide better texture approximation and discriminating capability. We have used benchmark segmentation datasets and metrics to evaluate the proposed texture descriptors. Experimental results on benchmark metrics and computational time are promising when the proposed texture features are used in the state-of-the-art iterative contraction and merging (ICM) image segmentation technique.
- Description: Doctor of Philosophy
- Authors: Tania, Sheikh
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Colour and texture are the most common features used in image processing and computer vision applications. Unlike colour, a local texture descriptor needs to express the unique variation pattern in the intensity differences of pixels in the neighbourhood of the pixel-of-interest (POI) so that it can sufficiently discriminate different textures. Since the descriptor needs spatial manipulation of all pixels in the neighbourhood of the POI, approximation of texture impacts not only the computational cost but also the performance of the applications. In this thesis, we aim to develop novel texture descriptors, especially for hierarchical image segmentation techniques that have recently gained popularity for their wide range of applications in medical imaging, video surveillance, autonomous navigation, and computer vision in general. To pursue the aim, we focus in reducing the length of the texture feature and directly modelling the distribution of intensity-variation in the parametric space of a probability density function (pdf). In the first contributory chapter, we enhance the state-of-the-art Weber local descriptor (WLD) by considering the mean value of neighbouring pixel intensities along radial directions instead of sampling pixels at three scales. Consequently, the proposed descriptor, named Radial Mean WLD (RM-WLD), is three-fold shorter than WLD and it performs slightly better than WLD in hierarchical image segmentation. The statistical distributions of pixel intensities in different image regions are diverse by nature. In the second contributory chapter, we propose a novel texture feature, called ‘joint scale,’ by directly modelling the probability distribution of intensity differences. The Weibull distribution, one of the extreme value distributions, is selected for this purpose as it can represent a wide range of probability distributions with a couple of parameters. In addition, gradient orientation feature is calculated from all pixels in the neighbourhood with an extended Sobel operator, instead of using only the vertical and horizontal neighbours as considered in WLD. The length of the texture descriptor combining joint scale and gradiet orientation features remains the same as RM-WLD, but it exhibits significantly improved discrimination capability for better image segmentation. Initial regions in hierarchical segmentation play an important role in approximating texture features. Traditional arbitrary-shaped initial regions maintain the uniform colour property and thus may not retain the texture pattern of the segment they belong to. In the final contributory chapter, we introduce regular-shaped initial regions by enhancing the cuboidal partitioning technique, which has recently gained popularity in image/video coding research. Since the regions (cuboids) of cuboidal partitioning are of rectangular shape, they do not follow the colour-based boundary adherence of traditional initial regions. Consequently, the cuboids retain sufficient texture pattern cues to provide better texture approximation and discriminating capability. We have used benchmark segmentation datasets and metrics to evaluate the proposed texture descriptors. Experimental results on benchmark metrics and computational time are promising when the proposed texture features are used in the state-of-the-art iterative contraction and merging (ICM) image segmentation technique.
- Description: Doctor of Philosophy
Enhancing Culturally and Linguistically Diverse (CALD) community understanding and utilisation of mental health services in Victoria
- Authors: Radhamony, Reshmy
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The increase in cultural diversity (CD) in Victoria, Australia, demands healthcare professionals to acquire cultural competence. Literature reveals that people from Culturally and Linguistically Diverse (CALD) communities can be disadvantaged in terms of mental health service access and utilisation and the appropriateness of the health care they receive following access. Cultural competence has been advocated as a necessary step to alleviate health disparities and reduce bias and prejudices associated with culturally diverse people. Cultural competence has been endorsed in the government and professional bodies’ policies and guidelines for a long time. Whether this has prepared the mental health nursing workforce with sufficient knowledge, skills, and attitude necessary to be culturally competent, is still questionable. Evidence shows that significant barriers such as language and communication, cultural differences, and a lack of cultural sensitivity by mental health nurses (MHN) limit the quality of care provided to people from various non-dominant cultures. The primary aim of this study was to examine whether an educational intervention can improve mental health nurses' knowledge, behaviour, and attitude. Hence this multiple-method study focused on the educational needs of a cross-section of MHNs in Victoria, utilising online surveys and semi-structured interviews. This project undertook a gap analysis through telephone interviews with the CALD community members in Victoria regarding their mental health service needs and experiences. Then developed, implemented, and evaluated an online education package – “Acknowledging Diversity”, regarding cultural awareness and responsiveness for mental health nurses working with people from CALD communities. A CIPP (Context, Input, Process and Product) model evaluation of the education package confirmed its effectiveness. Andersen's Behavioural Model of Health service use (ABMHSU) was the underlying theoretical framework for this study. The study's findings were further analysed using the contextual variables of Andersen’s model. The study outcome for mental health nurses was improved knowledge, attitude, and competence about the needs of people from CALD backgrounds, even though the findings were not statistically significant. However, it has been conceded that cultural competence cannot be achieved in a single education session. Therefore, attaining cultural proficiency is a continuous process that requires motivation and persistence from MHNs and ongoing cultural encounters with the CALD population. Examining how educational interventions improved MHNs’ cultural competency to facilitate CALD community understanding and utilisation of mental health services also identified the gaps in knowledge to report future research areas.
- Description: Doctor of Philosophy
- Authors: Radhamony, Reshmy
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The increase in cultural diversity (CD) in Victoria, Australia, demands healthcare professionals to acquire cultural competence. Literature reveals that people from Culturally and Linguistically Diverse (CALD) communities can be disadvantaged in terms of mental health service access and utilisation and the appropriateness of the health care they receive following access. Cultural competence has been advocated as a necessary step to alleviate health disparities and reduce bias and prejudices associated with culturally diverse people. Cultural competence has been endorsed in the government and professional bodies’ policies and guidelines for a long time. Whether this has prepared the mental health nursing workforce with sufficient knowledge, skills, and attitude necessary to be culturally competent, is still questionable. Evidence shows that significant barriers such as language and communication, cultural differences, and a lack of cultural sensitivity by mental health nurses (MHN) limit the quality of care provided to people from various non-dominant cultures. The primary aim of this study was to examine whether an educational intervention can improve mental health nurses' knowledge, behaviour, and attitude. Hence this multiple-method study focused on the educational needs of a cross-section of MHNs in Victoria, utilising online surveys and semi-structured interviews. This project undertook a gap analysis through telephone interviews with the CALD community members in Victoria regarding their mental health service needs and experiences. Then developed, implemented, and evaluated an online education package – “Acknowledging Diversity”, regarding cultural awareness and responsiveness for mental health nurses working with people from CALD communities. A CIPP (Context, Input, Process and Product) model evaluation of the education package confirmed its effectiveness. Andersen's Behavioural Model of Health service use (ABMHSU) was the underlying theoretical framework for this study. The study's findings were further analysed using the contextual variables of Andersen’s model. The study outcome for mental health nurses was improved knowledge, attitude, and competence about the needs of people from CALD backgrounds, even though the findings were not statistically significant. However, it has been conceded that cultural competence cannot be achieved in a single education session. Therefore, attaining cultural proficiency is a continuous process that requires motivation and persistence from MHNs and ongoing cultural encounters with the CALD population. Examining how educational interventions improved MHNs’ cultural competency to facilitate CALD community understanding and utilisation of mental health services also identified the gaps in knowledge to report future research areas.
- Description: Doctor of Philosophy
Enhancing illusionism within the encased contemporary art diorama through the integration of screen-based animated film
- Authors: Kronberger, Kenneth
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: In the late nineteen eighties artists started to create a highly illusionistic type of small scaled diorama, which I refer to as the encased contemporary art diorama. Such dioramas are typically presented encased in a box-like structure with a glazed viewing window situated at the front. Artifice such as realistically coloured and shaped miniature forms, strategically positioned mirrors and quantified atmospheric lighting are used to enhance the verisimilitude of the mimetic resemblance to life-sized reality. As a maker of animated films, I became curious about the ways in which illusionism within such dioramas might be enhanced through the integration of screen-based animated film. To pursue this line of enquiry, I first strove to understand how illusionism functions within encased contemporary art dioramas, and I travelled to Lyon, France to view an exhibition of such dioramas at the Musee Miniature et Cinema. As there is an apparent lack of text on how illusionism functions within such dioramas, I modelled my initial research on texts about illusionism in representational pictures, how artists create visual illusions and the role of the viewer in the formation and perception of illusions. I engaged the writing of Michael Fish to assist in identifying different illusion types. To fully view the interior of an encased contemporary art diorama, the viewer must alter the location of their eyes in relation to the diorama and its contents, concurrently the encasement prevents any tactile appraisal of the diorama’s contents. I refer to Maurice Merleau-Ponty’s phenomenology of embodiment to account for the ways the viewer’s embodiment can influence their perception of dioramic illusions. The outcomes of my studio practice include animated films, and dioramas both with and without screen-based animated film integrated within them. The resulting illusions achieved are appraised and discussed, limitations are identified, and future potentials contemplated.
- Description: Doctor of Philosophy
- Authors: Kronberger, Kenneth
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: In the late nineteen eighties artists started to create a highly illusionistic type of small scaled diorama, which I refer to as the encased contemporary art diorama. Such dioramas are typically presented encased in a box-like structure with a glazed viewing window situated at the front. Artifice such as realistically coloured and shaped miniature forms, strategically positioned mirrors and quantified atmospheric lighting are used to enhance the verisimilitude of the mimetic resemblance to life-sized reality. As a maker of animated films, I became curious about the ways in which illusionism within such dioramas might be enhanced through the integration of screen-based animated film. To pursue this line of enquiry, I first strove to understand how illusionism functions within encased contemporary art dioramas, and I travelled to Lyon, France to view an exhibition of such dioramas at the Musee Miniature et Cinema. As there is an apparent lack of text on how illusionism functions within such dioramas, I modelled my initial research on texts about illusionism in representational pictures, how artists create visual illusions and the role of the viewer in the formation and perception of illusions. I engaged the writing of Michael Fish to assist in identifying different illusion types. To fully view the interior of an encased contemporary art diorama, the viewer must alter the location of their eyes in relation to the diorama and its contents, concurrently the encasement prevents any tactile appraisal of the diorama’s contents. I refer to Maurice Merleau-Ponty’s phenomenology of embodiment to account for the ways the viewer’s embodiment can influence their perception of dioramic illusions. The outcomes of my studio practice include animated films, and dioramas both with and without screen-based animated film integrated within them. The resulting illusions achieved are appraised and discussed, limitations are identified, and future potentials contemplated.
- Description: Doctor of Philosophy
Evaluating explanations of artificial intelligence decisions : the explanation quality rubric and survey
- Authors: Young, Charlotte
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The use of Artificial Intelligence (AI) algorithms is growing rapidly (Vilone & Longo, 2020). With this comes an increasing demand for reliable, robust explanations of AI decisions. There is a pressing need for a way to evaluate their quality. This thesis examines these research questions: What would a rigorous, empirically justified, human-centred scheme for evaluating AI-decision explanations look like? How can a rigorous, empirically justified, human-centred scheme for evaluating AI-decision explanations be created? Can a rigorous, empirically justified, human-centred scheme for evaluating AI-decision explanations be used to improve explanations? Current Explainable Artificial Intelligence (XAI) research lacks an accepted, widely employed method for evaluating AI explanations. This thesis offers a method for creating a rigorous, empirically justified, human-centred scheme for evaluating AI-decision explanations. It uses this to create an evaluation methodology, the XQ Rubric and XQ Survey. The XQ Rubric and Survey are then employed to improve explanations of AI decisions. The thesis asks what constitutes a good explanation in the context of XAI. It provides: 1. a model of good explanation for use in XAI research 2. a method of gathering non-expert evaluations of XAI explanations 3. an evaluation scheme for non-experts to employ in assessing XAI explanations (XQ Rubric and XQ Survey). The thesis begins with a literature review, primarily an exploration of previous attempts to evaluate XAI explanations formally. This is followed by an account of the development and iterative refinement of a solution to the problem, the eXplanation Quality Rubric (XQ Rubric). A Design Science methodology was used to guide the XQ Rubric and XQ Survey development. The thesis limits itself to XAI explanations appropriate for non-experts. It proposes and tests an evaluation rubric and survey method that is both stable and robust: that is, readily usable and consistently reliable in a variety of XAI-explanation tasks.
- Description: Doctor of Philosophy
- Authors: Young, Charlotte
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The use of Artificial Intelligence (AI) algorithms is growing rapidly (Vilone & Longo, 2020). With this comes an increasing demand for reliable, robust explanations of AI decisions. There is a pressing need for a way to evaluate their quality. This thesis examines these research questions: What would a rigorous, empirically justified, human-centred scheme for evaluating AI-decision explanations look like? How can a rigorous, empirically justified, human-centred scheme for evaluating AI-decision explanations be created? Can a rigorous, empirically justified, human-centred scheme for evaluating AI-decision explanations be used to improve explanations? Current Explainable Artificial Intelligence (XAI) research lacks an accepted, widely employed method for evaluating AI explanations. This thesis offers a method for creating a rigorous, empirically justified, human-centred scheme for evaluating AI-decision explanations. It uses this to create an evaluation methodology, the XQ Rubric and XQ Survey. The XQ Rubric and Survey are then employed to improve explanations of AI decisions. The thesis asks what constitutes a good explanation in the context of XAI. It provides: 1. a model of good explanation for use in XAI research 2. a method of gathering non-expert evaluations of XAI explanations 3. an evaluation scheme for non-experts to employ in assessing XAI explanations (XQ Rubric and XQ Survey). The thesis begins with a literature review, primarily an exploration of previous attempts to evaluate XAI explanations formally. This is followed by an account of the development and iterative refinement of a solution to the problem, the eXplanation Quality Rubric (XQ Rubric). A Design Science methodology was used to guide the XQ Rubric and XQ Survey development. The thesis limits itself to XAI explanations appropriate for non-experts. It proposes and tests an evaluation rubric and survey method that is both stable and robust: that is, readily usable and consistently reliable in a variety of XAI-explanation tasks.
- Description: Doctor of Philosophy
Every crypto breath in the world : the current global position of the cryptocurrency market and future prediction
- Authors: Jayawardhana, Asanga
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: This study was motivated by the breakthrough of cryptocurrencies in 2018. The other main reasons behind the motivation are the total market capitalisation of one trillion-dollar diversification possibilities and the lack of preceding scientific research to identify the portfolio diversification possibilities of cryptocurrencies from many angles. Four empirical studies were conducted to provide a holistic view of cryptocurrency as an investment tool. The first study investigated the portfolio diversification possibilities between cryptocurrencies and traditional financial markets. A quantitative method was employed with Cointegration, ARDL bound testing approach, causality, and co-movement testing. Applying Modern portfolio theory to identify the diversification possibilities between the aforementioned markets enabled the study to highlight how investors can reap the benefits of cryptocurrencies. The second study extended the investigation of the portfolio diversification possibilities of cryptocurrency by including precious metals and cryptocurrencies in the same investment basket. Investors switch from traditional investment assets, such as equity and debt market instruments, to precious metal markets to reap benefits. Therefore, this study investigates how cryptocurrency can be an alternative source of investment to include in an investment portfolio. The daily precious metal and cryptocurrency data from 2017 to 2022 was utilised through an ARDL framework to obtain the Cointegration between cryptocurrency, precious metal and across cryptocurrencies. Modern portfolio theory is used to identify the diversification possibilities in this study with different portfolio diversification strategies. The third study clarified the cryptocurrency stakeholders to identify the global perception of cryptocurrency investments. A qualitative method was employed with sentiment analysis, followed by data extractions from the global databases using machine learning algorithms. The study identified the percentage of stakeholder groups' positive, negative, and neutral perceptions of cryptocurrency. The main obstacles hindering cryptocurrency investment growth are the fear of current scams, lack of definitional issues and the absence of a legal framework in some countries. The fourth study included the findings from the first, second and third studies to develop a cryptocurrency predictive model by factoring in macroeconomic variables. Panel data regression with fixed and dynamic effects was employed to analyse the data from 2017 to 2002. The findings suggest the impact of each macroeconomic variable selected in the study for the cryptocurrency price changes while adding more significance to technological variables. The overall findings provide strong support for the portfolio diversification possibilities of cryptocurrencies. Inclusions of the wide range of investment classes, exploring stakeholder perception and highlighting the macroeconomic variables' influence on the cryptocurrency price prediction generate new insights and valuable comparisons about cryptocurrency markets for academia, crypto issuers, investors, government, policymakers, and fund managers to use as an investment and decision-support tools. Keywords: Cryptocurrency, ARDL, Financial Markets, Cointegration, Causality, Portfolio diversification, Precious Metals, Predictive model.
- Description: Doctor of Philosophy
- Authors: Jayawardhana, Asanga
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: This study was motivated by the breakthrough of cryptocurrencies in 2018. The other main reasons behind the motivation are the total market capitalisation of one trillion-dollar diversification possibilities and the lack of preceding scientific research to identify the portfolio diversification possibilities of cryptocurrencies from many angles. Four empirical studies were conducted to provide a holistic view of cryptocurrency as an investment tool. The first study investigated the portfolio diversification possibilities between cryptocurrencies and traditional financial markets. A quantitative method was employed with Cointegration, ARDL bound testing approach, causality, and co-movement testing. Applying Modern portfolio theory to identify the diversification possibilities between the aforementioned markets enabled the study to highlight how investors can reap the benefits of cryptocurrencies. The second study extended the investigation of the portfolio diversification possibilities of cryptocurrency by including precious metals and cryptocurrencies in the same investment basket. Investors switch from traditional investment assets, such as equity and debt market instruments, to precious metal markets to reap benefits. Therefore, this study investigates how cryptocurrency can be an alternative source of investment to include in an investment portfolio. The daily precious metal and cryptocurrency data from 2017 to 2022 was utilised through an ARDL framework to obtain the Cointegration between cryptocurrency, precious metal and across cryptocurrencies. Modern portfolio theory is used to identify the diversification possibilities in this study with different portfolio diversification strategies. The third study clarified the cryptocurrency stakeholders to identify the global perception of cryptocurrency investments. A qualitative method was employed with sentiment analysis, followed by data extractions from the global databases using machine learning algorithms. The study identified the percentage of stakeholder groups' positive, negative, and neutral perceptions of cryptocurrency. The main obstacles hindering cryptocurrency investment growth are the fear of current scams, lack of definitional issues and the absence of a legal framework in some countries. The fourth study included the findings from the first, second and third studies to develop a cryptocurrency predictive model by factoring in macroeconomic variables. Panel data regression with fixed and dynamic effects was employed to analyse the data from 2017 to 2002. The findings suggest the impact of each macroeconomic variable selected in the study for the cryptocurrency price changes while adding more significance to technological variables. The overall findings provide strong support for the portfolio diversification possibilities of cryptocurrencies. Inclusions of the wide range of investment classes, exploring stakeholder perception and highlighting the macroeconomic variables' influence on the cryptocurrency price prediction generate new insights and valuable comparisons about cryptocurrency markets for academia, crypto issuers, investors, government, policymakers, and fund managers to use as an investment and decision-support tools. Keywords: Cryptocurrency, ARDL, Financial Markets, Cointegration, Causality, Portfolio diversification, Precious Metals, Predictive model.
- Description: Doctor of Philosophy
Examining the assessment and development of a fundamental motor skill and the efficacy of peer teaching instructional approaches
- Authors: Beseler, Bradley
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The overall purpose of this dissertation was to examine the process of assessing and developing the Fundamental Motor Skills (FMS) of overarm throwing. This dissertation involved two foci: qualitative assessment of FMS and the efficacy of peer teaching approaches. The first focus was to contribute to qualitative assessment of FMS research by examining an assessment system commonly used to assess overarm throwing development. The second focus was to examine the efficacy of peer teaching instructional approaches on improving overarm throwing performance of pre-service physical education (PE) teachers to determine whether these approaches could facilitate pre-service PE teachers to efficiently develop FMS proficiency. PE teachers who can proficiently perform FMS are better equipped to teach these skills; their demonstrations provide the learners a “blueprint” of the skill they are trying to acquire. The research includes four separate studies. The first two studies examined Roberton’s levels (Roberton & Halverson, 1984), a qualitative assessment system used extensively for over four decades to research overarm throwing development, primarily examining the technique of children and older throwers. Study 1 attempted to validate one of the backswing sequences (Haywood et al., 1991) to authenticate it for assessing the backswing component of university-aged throwers. The findings provided preliminary support that the Haywood et al. backswing sequence, previously only validated for assessing the backswing technique of older throwers, was suitable for assessing the backswing of the university-aged throwers. Study 2 examined the impact of the follow-through on throwing velocity. Findings showed the follow-through had the second largest impact on throwing velocity of all the six components, providing preliminary support for the inclusion of the follow-through component to the existing five components of Roberton’s (Roberton & Halverson, 1984) levels, making this system more accurate and comprehensive. Study 3 and 4 both utilised a quasi-experimenal between-subjects pre-test, intervention, post-test, and retention test designs. The participants were allocated to one of three experimental groups: a Video Analysis Group (VAG), a Verbal Group (VG), and a Control Group (CG). During the interventions the VAG and VG worked in pairs in a Reciprocal style of peer teaching (Mosston & Ashworth, 2002). The VAG and VG interventions were identical except the VAG had access to video analysis technology and the CG completed unrelated course work. Study 3, a single session intervention, and Study 4, a three-session intervention, attempted to ascertain whether video analysis affects throwing technique of participants working in reciprocal peer teaching settings. The findings indicated the impact of video analysis may be dependent on the number of intervention sessions. In Study 3, video analysis in a single session intervention appeared to accelerate the participants throwing improvement. Study 4 revealed video analysis was not vital over the course of the three sessions. The VAG and VG achieved similar throwing improvements that were superior to the CG who did not experience the peer teaching intervention. The findings from this dissertation have identified scope for the Roberton’s levels (Roberton & Halverson, 1984) to be refined and the two peer teaching instructional approaches examined have been shown to be effective when trying to develop overarm throwing. Furthermore, these findings can inform Physical Education Teacher Education Programs, potentially preparing graduate PE teachers more effectively to develop their students’ FMS, which may increase the involvement of children and adolescents in sport and physical activity because they will have the necessary skills to successfully engage in these activities.
- Description: Doctor of Philosophy
- Authors: Beseler, Bradley
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The overall purpose of this dissertation was to examine the process of assessing and developing the Fundamental Motor Skills (FMS) of overarm throwing. This dissertation involved two foci: qualitative assessment of FMS and the efficacy of peer teaching approaches. The first focus was to contribute to qualitative assessment of FMS research by examining an assessment system commonly used to assess overarm throwing development. The second focus was to examine the efficacy of peer teaching instructional approaches on improving overarm throwing performance of pre-service physical education (PE) teachers to determine whether these approaches could facilitate pre-service PE teachers to efficiently develop FMS proficiency. PE teachers who can proficiently perform FMS are better equipped to teach these skills; their demonstrations provide the learners a “blueprint” of the skill they are trying to acquire. The research includes four separate studies. The first two studies examined Roberton’s levels (Roberton & Halverson, 1984), a qualitative assessment system used extensively for over four decades to research overarm throwing development, primarily examining the technique of children and older throwers. Study 1 attempted to validate one of the backswing sequences (Haywood et al., 1991) to authenticate it for assessing the backswing component of university-aged throwers. The findings provided preliminary support that the Haywood et al. backswing sequence, previously only validated for assessing the backswing technique of older throwers, was suitable for assessing the backswing of the university-aged throwers. Study 2 examined the impact of the follow-through on throwing velocity. Findings showed the follow-through had the second largest impact on throwing velocity of all the six components, providing preliminary support for the inclusion of the follow-through component to the existing five components of Roberton’s (Roberton & Halverson, 1984) levels, making this system more accurate and comprehensive. Study 3 and 4 both utilised a quasi-experimenal between-subjects pre-test, intervention, post-test, and retention test designs. The participants were allocated to one of three experimental groups: a Video Analysis Group (VAG), a Verbal Group (VG), and a Control Group (CG). During the interventions the VAG and VG worked in pairs in a Reciprocal style of peer teaching (Mosston & Ashworth, 2002). The VAG and VG interventions were identical except the VAG had access to video analysis technology and the CG completed unrelated course work. Study 3, a single session intervention, and Study 4, a three-session intervention, attempted to ascertain whether video analysis affects throwing technique of participants working in reciprocal peer teaching settings. The findings indicated the impact of video analysis may be dependent on the number of intervention sessions. In Study 3, video analysis in a single session intervention appeared to accelerate the participants throwing improvement. Study 4 revealed video analysis was not vital over the course of the three sessions. The VAG and VG achieved similar throwing improvements that were superior to the CG who did not experience the peer teaching intervention. The findings from this dissertation have identified scope for the Roberton’s levels (Roberton & Halverson, 1984) to be refined and the two peer teaching instructional approaches examined have been shown to be effective when trying to develop overarm throwing. Furthermore, these findings can inform Physical Education Teacher Education Programs, potentially preparing graduate PE teachers more effectively to develop their students’ FMS, which may increase the involvement of children and adolescents in sport and physical activity because they will have the necessary skills to successfully engage in these activities.
- Description: Doctor of Philosophy
Factors affecting the organisational adoption of blockchain technology in australia : a mixed-methods approach
- Authors: Malik, Muhammad Saleem
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Blockchain (BCT) is an emerging technology that promises many benefits for organisations, such as disintermediation, data security, data transparency, a single version of the truth, and trust among trading partners. Despite its multiple benefits, the adoption rate of BCT among organisations has not reached a significantly high level worldwide. The present thesis addresses this issue in the Australian context. There is a knowledge gap in what specific factors, among the plethora of factors reported in the extant scholarly and commercial literature, affect Australian organisations while deciding to adopt BCT. To fill this gap, this thesis uses a mixed-methods approach known as sequential exploratory mixed methods. In this approach, the research starts with a qualitative phase as an initial phase followed by a quantitative phase. During the qualitative phase, data were collected through semi-structured interviews of the BCT experts and decision-makers working with the ifferent Australian organisations that adopted or were in the process of adopting BCT. The Technology, Organisation, Environment (TOE) framework, based on the qualitative interpretative approach, was used as a theoretical lens during the qualitative phase. The qualitative data were analyzed using the thematic analysis technique with the SQR NVivo software. The analysis shows that the different factors, belonging to the technological, organisational, and environmental contexts, affect the organisational decision to adopt BCT in Australia. The technological factors include perceived benefits, perceived computability, perceived complexity, perceived disintermediation, and perceived information transparency; organisational factors are organisational innovativeness, organisational learning capability, top management support; environmental factors consist of government support, standards uncertainty, competition intensity, and trading partners readiness. The qualitative analysis also shows the direct and moderating effect of the perceived risks between the relationship of the identified factors and organisational adoption of BCT. Based on the findings of the qualitative phase, the thesis develops a theoretical conceptual model, which shows the relationship between the factors and the organisational adoption of BCT. To increase the external validity of the developed conceptual model, the thesis started a quantitative phase with the administration of an online survey for data collection. Certain criteria were set to screen out the irrelevant participants in the survey. During this phase, hypotheses were proposed for the relationship of the factors identified in the qualitative phase and the organisational adoption of BCT. The survey data was analyzed using the PLS Structural Equation Modelling (SEM) technique with the SmartPLS 3 software. The quantitative analysis confirms the findings of the qualitative phase that the perceived benefits, perceived compatibility, perceived information transparency, perceived disintermediation, organisational innovativeness, organisational learning capability, top management support, competitive intensity, government support, and trading partner readiness have a positive effect on the organisational adoption of BCT. Whereas the perceived complexity, standards uncertainty, and perceived risks have a negative effect. The analysis also shows that the moderating effects of perceived risks are significant in the relationship of perceived compatibility, perceived information transparency, perceived disintermediation, organisational innovativeness, organisation innovativeness, competition intensity, and organisational adoption of BCT. Contrary to the qualitative findings, ‘perceived risks’ has no moderating effects on the relationship of perceived benefits, organisational learning capability, top management support, government support, trading partner readiness, and the adoption of BCT. The thesis has both theoretical and practical contributions, which are useful both for theory development and decision-making for the adoption of BCT in Australia. Theoretically, this thesis contributes to the existing IT adoption literature in several ways. Firstly, the thesis provides empirical evidence about the factors affecting organisational adoption of BCT in Australia. This is the first in-depth sequential exploratory mixed methods research that bridges this knowledge gap in the extant literature. The identification of such factors is important, particularly for the Australian government and organisations interested in the value creation of BCT. Second, the thesis reports the effect of new factors, namely, perceived information transparency, perceived disintermediation, organisational innovativeness, organisational learning capability, standards uncertainty, trading partner readiness, and competition intensity on BCT adoption that are exclusively identified in this research. Third, this thesis confirms the findings of the past studies that the factors of perceived benefits and perceived compatibility, perceived complexity, and top management support have an effect on the organisational adoption of BCT. Fourth, according to the best of the authors' knowledge, this is the first research that has used the qualitative interpretive research approach to investigate the organisational adoption of BCT. Therefore, the thesis confirms the suitability of the qualitative interpretive research approach for BCT adoption. Lastly, most of the researchers have used the TOE framework in either in qualitative or quantitative research. This thesis proves its validity in mixed methods research as well. The thesis's practical contributions are discussed in chapter 7.
- Description: Doctor of Philosophy
- Authors: Malik, Muhammad Saleem
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Blockchain (BCT) is an emerging technology that promises many benefits for organisations, such as disintermediation, data security, data transparency, a single version of the truth, and trust among trading partners. Despite its multiple benefits, the adoption rate of BCT among organisations has not reached a significantly high level worldwide. The present thesis addresses this issue in the Australian context. There is a knowledge gap in what specific factors, among the plethora of factors reported in the extant scholarly and commercial literature, affect Australian organisations while deciding to adopt BCT. To fill this gap, this thesis uses a mixed-methods approach known as sequential exploratory mixed methods. In this approach, the research starts with a qualitative phase as an initial phase followed by a quantitative phase. During the qualitative phase, data were collected through semi-structured interviews of the BCT experts and decision-makers working with the ifferent Australian organisations that adopted or were in the process of adopting BCT. The Technology, Organisation, Environment (TOE) framework, based on the qualitative interpretative approach, was used as a theoretical lens during the qualitative phase. The qualitative data were analyzed using the thematic analysis technique with the SQR NVivo software. The analysis shows that the different factors, belonging to the technological, organisational, and environmental contexts, affect the organisational decision to adopt BCT in Australia. The technological factors include perceived benefits, perceived computability, perceived complexity, perceived disintermediation, and perceived information transparency; organisational factors are organisational innovativeness, organisational learning capability, top management support; environmental factors consist of government support, standards uncertainty, competition intensity, and trading partners readiness. The qualitative analysis also shows the direct and moderating effect of the perceived risks between the relationship of the identified factors and organisational adoption of BCT. Based on the findings of the qualitative phase, the thesis develops a theoretical conceptual model, which shows the relationship between the factors and the organisational adoption of BCT. To increase the external validity of the developed conceptual model, the thesis started a quantitative phase with the administration of an online survey for data collection. Certain criteria were set to screen out the irrelevant participants in the survey. During this phase, hypotheses were proposed for the relationship of the factors identified in the qualitative phase and the organisational adoption of BCT. The survey data was analyzed using the PLS Structural Equation Modelling (SEM) technique with the SmartPLS 3 software. The quantitative analysis confirms the findings of the qualitative phase that the perceived benefits, perceived compatibility, perceived information transparency, perceived disintermediation, organisational innovativeness, organisational learning capability, top management support, competitive intensity, government support, and trading partner readiness have a positive effect on the organisational adoption of BCT. Whereas the perceived complexity, standards uncertainty, and perceived risks have a negative effect. The analysis also shows that the moderating effects of perceived risks are significant in the relationship of perceived compatibility, perceived information transparency, perceived disintermediation, organisational innovativeness, organisation innovativeness, competition intensity, and organisational adoption of BCT. Contrary to the qualitative findings, ‘perceived risks’ has no moderating effects on the relationship of perceived benefits, organisational learning capability, top management support, government support, trading partner readiness, and the adoption of BCT. The thesis has both theoretical and practical contributions, which are useful both for theory development and decision-making for the adoption of BCT in Australia. Theoretically, this thesis contributes to the existing IT adoption literature in several ways. Firstly, the thesis provides empirical evidence about the factors affecting organisational adoption of BCT in Australia. This is the first in-depth sequential exploratory mixed methods research that bridges this knowledge gap in the extant literature. The identification of such factors is important, particularly for the Australian government and organisations interested in the value creation of BCT. Second, the thesis reports the effect of new factors, namely, perceived information transparency, perceived disintermediation, organisational innovativeness, organisational learning capability, standards uncertainty, trading partner readiness, and competition intensity on BCT adoption that are exclusively identified in this research. Third, this thesis confirms the findings of the past studies that the factors of perceived benefits and perceived compatibility, perceived complexity, and top management support have an effect on the organisational adoption of BCT. Fourth, according to the best of the authors' knowledge, this is the first research that has used the qualitative interpretive research approach to investigate the organisational adoption of BCT. Therefore, the thesis confirms the suitability of the qualitative interpretive research approach for BCT adoption. Lastly, most of the researchers have used the TOE framework in either in qualitative or quantitative research. This thesis proves its validity in mixed methods research as well. The thesis's practical contributions are discussed in chapter 7.
- Description: Doctor of Philosophy
False data injection attack detection in smart grid
- Authors: Rashed, Muhammad
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Smart grid is a distributed and autonomous energy delivery infrastructure that constantly monitors the operational state of its overall network using smart techniques and state estimation. State estimation is a powerful technique that is used to determine the overall operational state of the system based on a limited set of measurements collected through metering systems. Cyber-attacks pose serious risks to a smart grid state estimation that can cause disruptions and power outages resulting in huge economical losses and are therefore a big concern to a reliable national grid operation. False data injection attacks (FDIAs), engineered on the basis of the knowledge of the network configuration, are difficult to detect using the traditional data detection mechanisms. These detection schemes have been found vulnerable and failed to detect these FDIAs. FDIAs specifically target the state data and can manipulate the state measurements in such a way that these false measurements appear real to the main control systems. This research work explores the possibility of FDIA detection using state estimation in a distributed and partitioned smart grid. In order to detect FDIAs we use measurements for residual-based testing which creates an objective function; and the probability of erroneous data is determined from this residual test. In this test, a preset threshold is determined based on the prior history of the state data. FDIA cases are simulated within a smart grid considering that the Chi-square detection state estimator fails in identifying such attacks. We compute the objective function using the standard weighted least problem and then test the objective function against the value in the Chi-square table. The gain matrix and the Jacobian matrix are computed. The state variables are computed in the form of a voltage magnitude. The state variables are computed after the inception of an attack to assess these state magnitude results. Different sizes of partitioning are used to improve the overall sensitivity of the Chi-square results. Our additional estimator is based on a Kalman estimation that consists of the state prediction and state correction steps. In the first step, it obtains the state and matrix covariance prediction, and in the second step, it calculates the Kalman gain and the state and matrix covariance update steps. The set of points is created for the state vector x at a time instant t. The initial vector and covariance matrix are based on a priori knowledge of the historical estimates. A set of sigma points is estimated by the state update function. Sigma points refer to the minimal set of sampling points that are selected and transformed using nonlinear function, and the new mean and the covariance are formed out of these transformed points. The idea behind this is that it is easier to compute a Gaussian distribution than an arbitrary nonlinear function. The filter gain, the mean and the covariance are used to estimate the next state. Our simulation results show that the combination of Kalman estimation and distributed state estimation improves the overall stability index and vulnerability assessment score of the smart grid. We built a stability index table for a smart grid based on the state estimates value after the inception of an FDIA. The vulnerability assessment score of the smart grid is based on common vulnerability scoring system (CVSS) and state estimates under the influence of an FDIA. The simulations are conducted in the MATPOWER program and different electrical bus systems such as IEEE 14, 30, 39, 118 and 300 are tested. All the contributions have been published in reputable journals and conferences.
- Description: Doctor of Philosophy
- Authors: Rashed, Muhammad
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Smart grid is a distributed and autonomous energy delivery infrastructure that constantly monitors the operational state of its overall network using smart techniques and state estimation. State estimation is a powerful technique that is used to determine the overall operational state of the system based on a limited set of measurements collected through metering systems. Cyber-attacks pose serious risks to a smart grid state estimation that can cause disruptions and power outages resulting in huge economical losses and are therefore a big concern to a reliable national grid operation. False data injection attacks (FDIAs), engineered on the basis of the knowledge of the network configuration, are difficult to detect using the traditional data detection mechanisms. These detection schemes have been found vulnerable and failed to detect these FDIAs. FDIAs specifically target the state data and can manipulate the state measurements in such a way that these false measurements appear real to the main control systems. This research work explores the possibility of FDIA detection using state estimation in a distributed and partitioned smart grid. In order to detect FDIAs we use measurements for residual-based testing which creates an objective function; and the probability of erroneous data is determined from this residual test. In this test, a preset threshold is determined based on the prior history of the state data. FDIA cases are simulated within a smart grid considering that the Chi-square detection state estimator fails in identifying such attacks. We compute the objective function using the standard weighted least problem and then test the objective function against the value in the Chi-square table. The gain matrix and the Jacobian matrix are computed. The state variables are computed in the form of a voltage magnitude. The state variables are computed after the inception of an attack to assess these state magnitude results. Different sizes of partitioning are used to improve the overall sensitivity of the Chi-square results. Our additional estimator is based on a Kalman estimation that consists of the state prediction and state correction steps. In the first step, it obtains the state and matrix covariance prediction, and in the second step, it calculates the Kalman gain and the state and matrix covariance update steps. The set of points is created for the state vector x at a time instant t. The initial vector and covariance matrix are based on a priori knowledge of the historical estimates. A set of sigma points is estimated by the state update function. Sigma points refer to the minimal set of sampling points that are selected and transformed using nonlinear function, and the new mean and the covariance are formed out of these transformed points. The idea behind this is that it is easier to compute a Gaussian distribution than an arbitrary nonlinear function. The filter gain, the mean and the covariance are used to estimate the next state. Our simulation results show that the combination of Kalman estimation and distributed state estimation improves the overall stability index and vulnerability assessment score of the smart grid. We built a stability index table for a smart grid based on the state estimates value after the inception of an FDIA. The vulnerability assessment score of the smart grid is based on common vulnerability scoring system (CVSS) and state estimates under the influence of an FDIA. The simulations are conducted in the MATPOWER program and different electrical bus systems such as IEEE 14, 30, 39, 118 and 300 are tested. All the contributions have been published in reputable journals and conferences.
- Description: Doctor of Philosophy
History of the Ballarat Trades and Labour Council 1856-2000
- Authors: Beacham, Jennifer
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The Ballarat Trades and Labour Council (BT&LC) is the second oldest trades and labour council in the world, founded in 1883, although it has existed in various forms since 1856. This thesis examines the history of the BT&LC in terms of five related themes – ideological conflict, solidarity, labourism, masculinity, and spatiality. I approached this research project from the perspective of a labour historian, which also included issues of gender. While being resolute in writing the history of this institution, my aim was also to capture an aspect of Ballarat history that had not been examined before – the role of workers and their families. The BT&LC sets the parameters of its history from the Eureka Rebellion and gaining the Eight Hour Day for Ballarat stonemasons in 1856 a fortnight after their Melbourne counterparts. Since that time, the BT&LC has built the substantial Trades Hall in Camp Street, which it still occupies and hosted the Seventh Intercolonial Trade Union Congress in 1891 when the decision to seek political representation was formally endorsed. It witnessed the emergence of the new elites and the ideological struggle that became more bitter as the Catholic Church, Protestant Freemasons, and the very active Communist Party battled for supremacy, with it ending inevitably in a divisive public separation in 1955. The Whitlam years saw their resurgence with a new face to unionism as public sector workers, teachers and nurses became militant and women began to take significant roles. In Ballarat while this has meant political ascendancy since 1980, the success of the political wing has not necessarily been mirrored in the fortunes of the peak union organisation. Ballarat’s overall union membership has declined. The old loyalties have been difficult to maintain and the capacity to build new alliances is challenging. However, one thing remains clear: strong individuals who understand the underpinnings of solidarity and unity have ensured that the Ballarat Trades and Labour Council has remained a significant feature of the Ballarat public landscape.
- Description: Doctor of Philosophy
- Authors: Beacham, Jennifer
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The Ballarat Trades and Labour Council (BT&LC) is the second oldest trades and labour council in the world, founded in 1883, although it has existed in various forms since 1856. This thesis examines the history of the BT&LC in terms of five related themes – ideological conflict, solidarity, labourism, masculinity, and spatiality. I approached this research project from the perspective of a labour historian, which also included issues of gender. While being resolute in writing the history of this institution, my aim was also to capture an aspect of Ballarat history that had not been examined before – the role of workers and their families. The BT&LC sets the parameters of its history from the Eureka Rebellion and gaining the Eight Hour Day for Ballarat stonemasons in 1856 a fortnight after their Melbourne counterparts. Since that time, the BT&LC has built the substantial Trades Hall in Camp Street, which it still occupies and hosted the Seventh Intercolonial Trade Union Congress in 1891 when the decision to seek political representation was formally endorsed. It witnessed the emergence of the new elites and the ideological struggle that became more bitter as the Catholic Church, Protestant Freemasons, and the very active Communist Party battled for supremacy, with it ending inevitably in a divisive public separation in 1955. The Whitlam years saw their resurgence with a new face to unionism as public sector workers, teachers and nurses became militant and women began to take significant roles. In Ballarat while this has meant political ascendancy since 1980, the success of the political wing has not necessarily been mirrored in the fortunes of the peak union organisation. Ballarat’s overall union membership has declined. The old loyalties have been difficult to maintain and the capacity to build new alliances is challenging. However, one thing remains clear: strong individuals who understand the underpinnings of solidarity and unity have ensured that the Ballarat Trades and Labour Council has remained a significant feature of the Ballarat public landscape.
- Description: Doctor of Philosophy
Initiating temperate grassland restoration by controlling the dominant weed species; a case study with Nassella trichotoma
- Authors: Humphries, Talia
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Temperate grasslands are globally important biomes, in that they (i) provide habitat for a wide diversity of species, (ii) sequester large stocks of carbon, and (iii) provide forage for important pollinators (Chapter 1). These ecosystems often fall within highly fertile areas, and consequently humans have come to depend on them to provide high quality forage for grazing livestock and land for agricultural development. Temperate grasslands are considered to be critically endangered on a global scale. The grazing industry relies upon healthy and productive grasslands for the production of a substantial proportion of human food products, however, when these systems incorporate unsustainable land-management practises, such as over-grazing and continual fertilisation with inorganic matter, has resulted in a significant decline in important native grass species. This has resulted in encroachment of unpalatable, noxious plants, which decrease the quality of available forage. One such noxious weed species, Nassella trichotoma, known commonly as serrated tussock, is having a significance impact on the constitution of temperate grasslands and grazing systems, globally, due to its unpalatability and competitive growth form. In order to return temperate grasslands to a fully-functional and a high-quality forage state, human intervention in terms of ecosystem restoration is required. The control of noxious species, together with the reintroduction and establishment of native species, is a critical step for restoration efforts with the return of native plant diversity, and the re-establishment of ecosystem services, such as habitat for higher trophic levels. This thesis reviews and overlaps the scientific disciplines of ecosystem restoration (Chapter 2), weed science relating to N. trichotoma (Chapter 3), and environmental management in order to provide solutions for controlling N. trichotoma in non-native grassland communities (Chapter 4). The effect of direct herbicide application, soil tillage, grazing exclusion, fire, and broadcasting native seeds for the control of this dominant weeds in a total of 13 different combinations is investigated. The experimental plots were surveyed over a four-year period and soil cores were collected over a three-year period to survey the seedbank density. It was found that the inclusion of fire significantly increased the establishment of the native broadcast species. Also, without the integration of fire or tillage, N. trichotoma recovered, and consequently was observed to be the dominant species in the final sampling period. To support the findings of Chapter 4, research into the seed longevity and seedbank persistence of N. trichotoma was undertaken in Chapter 5. It was found that less than 10% of the seeds were observed to be viable after 12 months of burial in field. In addition to this, the longevity of the seeds was determined by rapidly ageing the seeds through exposure to high relative humidity and temperature. This process determined that N. trichotoma produces transient seedbanks, referring to those that persist for 12 months or less, and therefore the seedbank would be reliant on new seed input annually to remain a competitive threat. This implies that management control of new seed fall is essential to prevent the reestablishment of the seed bank. The seedbank persistence for N. trichotoma is complicated by disturbance events such as fire. To investigate this impact, four different collection years; 2016, 2017, 2018, and 2019 were subjected to increasing heat (80, 100, 120, or 140OC) and time of exposure (1, 3, 6 or 9 minutes) by placing them into a temperature-controlled oven for the given treatment. It was found that only the 140OC treatment was significant for killing N. trichotoma, as detailed in Chapter 6. High moisture content (95%) increased the seeds sensitivity to radiant heat, with all tested temperature effective for killing this species. The seedlings were not killed by the tested treatments. Management implications and recommendations for the control of N. trichotoma in temperate grasslands (Chapter 7) include; (i) the use of herbicide in Autumn to prevent seed set in the following summer, and (ii) in addition to initial herbicide, use, subsequent fire treatment and broadcasting native seeds appear to provide ongoing competition against N. trichotoma reestablishment in treated areas. Further, high fire intensities, where the soil is heated to 140OC or more, can kill N. trichotoma’s seedbank and prevent its recruitment. In all cases of treatment, monitoring recruitment from the seedbank is recommended for up to one year after treating a site. This thesis suggests that localised eradication of N. trichotoma is achievable in as little as three years if (i) above-ground plants are treated, (ii) seedling recruitment from the seedbank is managed intensely within the first year, (iii) high densities of native grass is established to provide competition, and (iv) the addition of new seed is prevented.
- Description: Doctor of Philosophy
- Authors: Humphries, Talia
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Temperate grasslands are globally important biomes, in that they (i) provide habitat for a wide diversity of species, (ii) sequester large stocks of carbon, and (iii) provide forage for important pollinators (Chapter 1). These ecosystems often fall within highly fertile areas, and consequently humans have come to depend on them to provide high quality forage for grazing livestock and land for agricultural development. Temperate grasslands are considered to be critically endangered on a global scale. The grazing industry relies upon healthy and productive grasslands for the production of a substantial proportion of human food products, however, when these systems incorporate unsustainable land-management practises, such as over-grazing and continual fertilisation with inorganic matter, has resulted in a significant decline in important native grass species. This has resulted in encroachment of unpalatable, noxious plants, which decrease the quality of available forage. One such noxious weed species, Nassella trichotoma, known commonly as serrated tussock, is having a significance impact on the constitution of temperate grasslands and grazing systems, globally, due to its unpalatability and competitive growth form. In order to return temperate grasslands to a fully-functional and a high-quality forage state, human intervention in terms of ecosystem restoration is required. The control of noxious species, together with the reintroduction and establishment of native species, is a critical step for restoration efforts with the return of native plant diversity, and the re-establishment of ecosystem services, such as habitat for higher trophic levels. This thesis reviews and overlaps the scientific disciplines of ecosystem restoration (Chapter 2), weed science relating to N. trichotoma (Chapter 3), and environmental management in order to provide solutions for controlling N. trichotoma in non-native grassland communities (Chapter 4). The effect of direct herbicide application, soil tillage, grazing exclusion, fire, and broadcasting native seeds for the control of this dominant weeds in a total of 13 different combinations is investigated. The experimental plots were surveyed over a four-year period and soil cores were collected over a three-year period to survey the seedbank density. It was found that the inclusion of fire significantly increased the establishment of the native broadcast species. Also, without the integration of fire or tillage, N. trichotoma recovered, and consequently was observed to be the dominant species in the final sampling period. To support the findings of Chapter 4, research into the seed longevity and seedbank persistence of N. trichotoma was undertaken in Chapter 5. It was found that less than 10% of the seeds were observed to be viable after 12 months of burial in field. In addition to this, the longevity of the seeds was determined by rapidly ageing the seeds through exposure to high relative humidity and temperature. This process determined that N. trichotoma produces transient seedbanks, referring to those that persist for 12 months or less, and therefore the seedbank would be reliant on new seed input annually to remain a competitive threat. This implies that management control of new seed fall is essential to prevent the reestablishment of the seed bank. The seedbank persistence for N. trichotoma is complicated by disturbance events such as fire. To investigate this impact, four different collection years; 2016, 2017, 2018, and 2019 were subjected to increasing heat (80, 100, 120, or 140OC) and time of exposure (1, 3, 6 or 9 minutes) by placing them into a temperature-controlled oven for the given treatment. It was found that only the 140OC treatment was significant for killing N. trichotoma, as detailed in Chapter 6. High moisture content (95%) increased the seeds sensitivity to radiant heat, with all tested temperature effective for killing this species. The seedlings were not killed by the tested treatments. Management implications and recommendations for the control of N. trichotoma in temperate grasslands (Chapter 7) include; (i) the use of herbicide in Autumn to prevent seed set in the following summer, and (ii) in addition to initial herbicide, use, subsequent fire treatment and broadcasting native seeds appear to provide ongoing competition against N. trichotoma reestablishment in treated areas. Further, high fire intensities, where the soil is heated to 140OC or more, can kill N. trichotoma’s seedbank and prevent its recruitment. In all cases of treatment, monitoring recruitment from the seedbank is recommended for up to one year after treating a site. This thesis suggests that localised eradication of N. trichotoma is achievable in as little as three years if (i) above-ground plants are treated, (ii) seedling recruitment from the seedbank is managed intensely within the first year, (iii) high densities of native grass is established to provide competition, and (iv) the addition of new seed is prevented.
- Description: Doctor of Philosophy
Machine learning-based optimal load balancing in software-defined networks
- Authors: Sharma, Aakanksha
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The global advancement of the Internet of Things (IoT) has poised the existing network traffic for explosive growth. The prediction in the literature shows that in the future, trillions of smart devices will connect to transfer useful information. Accommodating such proliferation of devices in the existing network infrastructure, referred to as the traditional network, is a significant challenge due to the absence of centralized control, making it tedious to implement the device management and network protocol updates. In addition, due to their inherently distributed features, applying machine learning mechanisms in traditional networks is demanding. Consequently, it leads to an imbalanced load in the network that affects the overall network Quality of Service (QoS). Expanding the existing infrastructure and manual traffic control methods are inadequate to cope with the exponential growth of IoT devices. Therefore, an intelligent system is necessary for future networks that can efficiently organize, manage, maintain, and optimize the growing networks. Software-defined network (SDN) has a holistic view of the network and is highly suitable for handling dynamic loads in the traditional network with a minimal update in the network infrastructure. However, the standard SDN architecture control plane has been designed for a single controller or multiple distributed controllers that faces severe bottleneck issues. Our initial research created a reference model for the traditional network, using the standard SDN (SDN) in a network simulator called NetSim. Based on the network traffic, the reference models consisted of light, modest and heavy networks depending on the number of connected IoT devices. Furthermore, the research was enhanced with a priority scheduling and congestion control algorithm in the standard SDN, named extended SDN (eSDN), which minimized the network congestion and performed better than the existing SDN. However, enhancement was suitable only for the small-scale network because, in a large-scale network, the eSDN does not support dynamic controller mapping in the network. Often, the same controller gets overloaded, leading to a single point of failure. Our exhaustive literature review shows that the majority of proposed solutions are based on static controller deployment without considering flow fluctuations and traffic bursts that lead to a lack of load balancing among controllers in real-time, eventually increasing the network latency. Often, the switch experiences a traffic burst, and consequently, the corresponding controller might overload. Therefore, to maintain the Quality of Service (QoS) in the network, it becomes imperative for the static controller to neutralize the on-the-fly traffic burst. Addressing the above-mentioned issues demands research critical to improving the QoS in load balancing, latency minimisation, and network reliability for next- generation networks. Our novel dynamic controller mapping algorithm with multiple- controller placement in the SDN is critical in solving the identified issues. In the dynamic controller approach (dSDN), the controllers are mapped dynamically as the load fluctuates. If any controller reaches its maximum threshold, the rest of the traffic will be diverted to another controller, significantly reducing delay and enhancing the overall performance. Our technique considers the latency and load fluctuation in the network and manages the situations where static mapping is ineffective in dealing with the dynamic flow variation. In addition, our novel approach adds more intelligence to the network with a Temporal Deep Q Learning (tDQN) approach for dynamic controller mapping when the flow fluctuates. In this technique, a multi-objective optimization problem for flow fluctuation is formulated to dynamically divert the traffic to the best-suited controller. The formulated technique is placed as an agent in the network controller to take care of all the routing decisions, which can solve the dynamic flow mapping and latency optimization without increasing the number of optimally placed controllers. Extensive simulation results show that the novel approach proposed in this thesis solves dynamic flow mapping by maintaining a balanced load among controllers and outperforms the existing traditional networks and SDN with priority scheduling and congestion control. Compared to traditional networks, tDQN provides a 47.48% increase in throughput, a 99.10% reduction in delay and a 97.98% reduction in jitter for heavy network traffic. The thesis also presents a few future research directions as possible extensions of the current work for further enhancement.
- Description: Doctor of Philosophy
- Authors: Sharma, Aakanksha
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The global advancement of the Internet of Things (IoT) has poised the existing network traffic for explosive growth. The prediction in the literature shows that in the future, trillions of smart devices will connect to transfer useful information. Accommodating such proliferation of devices in the existing network infrastructure, referred to as the traditional network, is a significant challenge due to the absence of centralized control, making it tedious to implement the device management and network protocol updates. In addition, due to their inherently distributed features, applying machine learning mechanisms in traditional networks is demanding. Consequently, it leads to an imbalanced load in the network that affects the overall network Quality of Service (QoS). Expanding the existing infrastructure and manual traffic control methods are inadequate to cope with the exponential growth of IoT devices. Therefore, an intelligent system is necessary for future networks that can efficiently organize, manage, maintain, and optimize the growing networks. Software-defined network (SDN) has a holistic view of the network and is highly suitable for handling dynamic loads in the traditional network with a minimal update in the network infrastructure. However, the standard SDN architecture control plane has been designed for a single controller or multiple distributed controllers that faces severe bottleneck issues. Our initial research created a reference model for the traditional network, using the standard SDN (SDN) in a network simulator called NetSim. Based on the network traffic, the reference models consisted of light, modest and heavy networks depending on the number of connected IoT devices. Furthermore, the research was enhanced with a priority scheduling and congestion control algorithm in the standard SDN, named extended SDN (eSDN), which minimized the network congestion and performed better than the existing SDN. However, enhancement was suitable only for the small-scale network because, in a large-scale network, the eSDN does not support dynamic controller mapping in the network. Often, the same controller gets overloaded, leading to a single point of failure. Our exhaustive literature review shows that the majority of proposed solutions are based on static controller deployment without considering flow fluctuations and traffic bursts that lead to a lack of load balancing among controllers in real-time, eventually increasing the network latency. Often, the switch experiences a traffic burst, and consequently, the corresponding controller might overload. Therefore, to maintain the Quality of Service (QoS) in the network, it becomes imperative for the static controller to neutralize the on-the-fly traffic burst. Addressing the above-mentioned issues demands research critical to improving the QoS in load balancing, latency minimisation, and network reliability for next- generation networks. Our novel dynamic controller mapping algorithm with multiple- controller placement in the SDN is critical in solving the identified issues. In the dynamic controller approach (dSDN), the controllers are mapped dynamically as the load fluctuates. If any controller reaches its maximum threshold, the rest of the traffic will be diverted to another controller, significantly reducing delay and enhancing the overall performance. Our technique considers the latency and load fluctuation in the network and manages the situations where static mapping is ineffective in dealing with the dynamic flow variation. In addition, our novel approach adds more intelligence to the network with a Temporal Deep Q Learning (tDQN) approach for dynamic controller mapping when the flow fluctuates. In this technique, a multi-objective optimization problem for flow fluctuation is formulated to dynamically divert the traffic to the best-suited controller. The formulated technique is placed as an agent in the network controller to take care of all the routing decisions, which can solve the dynamic flow mapping and latency optimization without increasing the number of optimally placed controllers. Extensive simulation results show that the novel approach proposed in this thesis solves dynamic flow mapping by maintaining a balanced load among controllers and outperforms the existing traditional networks and SDN with priority scheduling and congestion control. Compared to traditional networks, tDQN provides a 47.48% increase in throughput, a 99.10% reduction in delay and a 97.98% reduction in jitter for heavy network traffic. The thesis also presents a few future research directions as possible extensions of the current work for further enhancement.
- Description: Doctor of Philosophy
Meaning-sensitive noisy text analytics in the low data regime
- Authors: Kasthuriarachchy, Buddhika
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Digital connectivity is revolutionising people’s quality of life. As broadband and mobile services become faster and more prevalent globally than before, people have started to frequently express their wants and desires on social media platforms. Thus, deriving insights from text data has become a popular approach, both in the industry and academia, to provide social media analytics solutions across a range of disciplines, including consumer behaviour, sales, sports and sociology. Businesses can harness the data shared on social networks to improve their organisations’ strategic business decisions by leveraging advanced Natural Language Processing (NLP) techniques, such as context-aware representations. Specifically, SportsHosts, our industry partner, will be able to launch digital marketing solutions that optimise audience targeting and personalisation using NLP-powered solutions. However, social media data are often noisy and diverse, making the task very challenging. Further, real-world NLP tasks often suffer from insufficient labelled data due to the costly and time-consuming nature of manual annotation. Nevertheless, businesses are keen on maximising the return on investment by boosting the performance of these NLP models in the real world, particularly with social media data. In this thesis, we make several contributions to address these challenges. Firstly, we propose to improve the NLP model’s ability to comprehend noisy text in a low data regime by leveraging prior knowledge from pre-trained language models. Secondly, we analyse the impact of text augmentation and the quality of synthetic sentences in a context-aware NLP setting and propose a meaning-sensitive text augmentation technique using a Masked Language Model. Thirdly, we offer a cost-efficient text data annotation methodology and an end-to-end framework to deploy efficient and effective social media analytics solutions in the real world.
- Description: Doctor of Philosophy
- Authors: Kasthuriarachchy, Buddhika
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Digital connectivity is revolutionising people’s quality of life. As broadband and mobile services become faster and more prevalent globally than before, people have started to frequently express their wants and desires on social media platforms. Thus, deriving insights from text data has become a popular approach, both in the industry and academia, to provide social media analytics solutions across a range of disciplines, including consumer behaviour, sales, sports and sociology. Businesses can harness the data shared on social networks to improve their organisations’ strategic business decisions by leveraging advanced Natural Language Processing (NLP) techniques, such as context-aware representations. Specifically, SportsHosts, our industry partner, will be able to launch digital marketing solutions that optimise audience targeting and personalisation using NLP-powered solutions. However, social media data are often noisy and diverse, making the task very challenging. Further, real-world NLP tasks often suffer from insufficient labelled data due to the costly and time-consuming nature of manual annotation. Nevertheless, businesses are keen on maximising the return on investment by boosting the performance of these NLP models in the real world, particularly with social media data. In this thesis, we make several contributions to address these challenges. Firstly, we propose to improve the NLP model’s ability to comprehend noisy text in a low data regime by leveraging prior knowledge from pre-trained language models. Secondly, we analyse the impact of text augmentation and the quality of synthetic sentences in a context-aware NLP setting and propose a meaning-sensitive text augmentation technique using a Masked Language Model. Thirdly, we offer a cost-efficient text data annotation methodology and an end-to-end framework to deploy efficient and effective social media analytics solutions in the real world.
- Description: Doctor of Philosophy
Revision and validation of the Australian Competency Standards for Occupational Therapy Driver Assessors to ensure best practice
- Authors: Fields, Sally
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Occupational therapy driver assessment and rehabilitation is an advanced and complex area of practice. Users of this service require that occupational therapy driver assessors are, and remain, competent in their role. Competency standards support and inform occupational therapy driver assessment and rehabilitation practice, ensure standardisation of practice, and determine whether practice can be deemed competent. Competency standards for occupational therapy driver assessors in one Australian state, Victoria, were published in 1998 to provide a benchmark for service provision and guide training. Since then, occupational therapy driver assessor practice has undergone further developments and growth, including a significant increase in research evidence underpinning this advanced practice area. As a result, the competency standards required revision to reflect contemporary practice and enable their use and application across all Australian states and territories. The purpose of the research program reported in this thesis was to revise and validate the Australian Competency Standards for Occupational Therapy Driver Assessors and determine if education and practice using these standards led to increased adherence to their use in clinical practice. A sequential, exploratory, mixed methods design was used within a pragmatist research paradigm to revise and validate the competency standards for occupational therapy driver assessors from a national perspective. Four separate research studies were conducted. In the first study, an overview was undertaken to summarise the current evidence for including cognitive and perceptual assessments within fitness-to-drive evaluations, to inform the revision of the competency standards for occupational therapy driver assessors. The second study involved focus groups with Australian occupational therapy driver assessors and expert educators and identified the changes and revisions required to be made to the Victorian competency standards for occupational therapy driver assessors. Content themes and changes were extracted from the focus groups and combined with research evidence to draft the revised standards. The third study collected feedback from consumers and Australian driver licensing authorities to incorporate into the revised draft. This was followed by a two-round Delphi process with Australian occupational therapy driver assessors to achieve consensus and validate the Australian Competency Standards for Occupational Therapy Driver Assessors. A high level of consensus on the content of all competency standards and underlying practice behaviours was obtained in the final round. Finally, a mixed-methods multiple case-study methodology was adopted, and multiple forms of evidence were collected from file audits, semi-structured interviews and an individualised education session with occupational therapy driver assessors. This study demonstrated that, for this sample, occupational therapy driver assessors’ adherence to the Australian Competency Standards for Occupational Therapy Driver Assessors increased following an individually tailored education package about the standards. The research in this thesis has contributed to the evidence base for occupational therapy driver assessor practice. The Australian Competency Standards for Occupational Therapy Driver Assessors have been revised, validated and published, and the impact of an education package to increase adherence has been investigated. These competency standards: (i) assist occupational therapy driver assessors’ clinical practice, support occupational therapy registration and regulatory agencies to evaluate practice against a standard and (iii) provide universities with a framework to deliver postgraduate training in occupational therapy driver assessment and rehabilitation. Finally, this research has described a process that can be utilised in other areas of occupational therapy practice to develop and validate competency standards.
- Description: Doctor of Philosophy
- Authors: Fields, Sally
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Occupational therapy driver assessment and rehabilitation is an advanced and complex area of practice. Users of this service require that occupational therapy driver assessors are, and remain, competent in their role. Competency standards support and inform occupational therapy driver assessment and rehabilitation practice, ensure standardisation of practice, and determine whether practice can be deemed competent. Competency standards for occupational therapy driver assessors in one Australian state, Victoria, were published in 1998 to provide a benchmark for service provision and guide training. Since then, occupational therapy driver assessor practice has undergone further developments and growth, including a significant increase in research evidence underpinning this advanced practice area. As a result, the competency standards required revision to reflect contemporary practice and enable their use and application across all Australian states and territories. The purpose of the research program reported in this thesis was to revise and validate the Australian Competency Standards for Occupational Therapy Driver Assessors and determine if education and practice using these standards led to increased adherence to their use in clinical practice. A sequential, exploratory, mixed methods design was used within a pragmatist research paradigm to revise and validate the competency standards for occupational therapy driver assessors from a national perspective. Four separate research studies were conducted. In the first study, an overview was undertaken to summarise the current evidence for including cognitive and perceptual assessments within fitness-to-drive evaluations, to inform the revision of the competency standards for occupational therapy driver assessors. The second study involved focus groups with Australian occupational therapy driver assessors and expert educators and identified the changes and revisions required to be made to the Victorian competency standards for occupational therapy driver assessors. Content themes and changes were extracted from the focus groups and combined with research evidence to draft the revised standards. The third study collected feedback from consumers and Australian driver licensing authorities to incorporate into the revised draft. This was followed by a two-round Delphi process with Australian occupational therapy driver assessors to achieve consensus and validate the Australian Competency Standards for Occupational Therapy Driver Assessors. A high level of consensus on the content of all competency standards and underlying practice behaviours was obtained in the final round. Finally, a mixed-methods multiple case-study methodology was adopted, and multiple forms of evidence were collected from file audits, semi-structured interviews and an individualised education session with occupational therapy driver assessors. This study demonstrated that, for this sample, occupational therapy driver assessors’ adherence to the Australian Competency Standards for Occupational Therapy Driver Assessors increased following an individually tailored education package about the standards. The research in this thesis has contributed to the evidence base for occupational therapy driver assessor practice. The Australian Competency Standards for Occupational Therapy Driver Assessors have been revised, validated and published, and the impact of an education package to increase adherence has been investigated. These competency standards: (i) assist occupational therapy driver assessors’ clinical practice, support occupational therapy registration and regulatory agencies to evaluate practice against a standard and (iii) provide universities with a framework to deliver postgraduate training in occupational therapy driver assessment and rehabilitation. Finally, this research has described a process that can be utilised in other areas of occupational therapy practice to develop and validate competency standards.
- Description: Doctor of Philosophy
Single- and multiobjective reinforcement learning in dynamic adversarial games
- Authors: Kurniawan, Budi
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis uses reinforcement learning (RL) to address dynamic adversarial games in the context of air combat manoeuvring simulation. A sequential decision problem commonly encountered in the field of operations research, air combat manoeuvring simulation conventionally relied on agent programming methods that required significant domain knowledge to be manually encoded into the simulation environment. These methods are appropriate for determining the effectiveness of existing tactics in different simulated scenarios. However, in order to maximise the advantages provided by new technologies (such as autonomous aircraft), new tactics will need to be discovered. A proven technique for solving sequential decision problems, RL has the potential to discover these new tactics. This thesis explores four RL approaches—tabular, deep, discrete-to-deep and multiobjective— as mechanisms for discovering new behaviours in simulations of air combat manoeuvring. Itimplements and tests several methods for each approach and compares those methods in terms of the learning time, baseline and comparative performances, and implementation complexity. In addition to evaluating the utility of existing approaches to the specific task of air combat manoeuvring, this thesis proposes and investigates two novel methods, discrete-to-deep supervised policy learning (D2D-SPL) and discrete-to-deep supervised Q-value learning (D2D-SQL), which can be applied more generally. D2D-SPL and D2D-SQL offer the generalisability of deep RL at a cost closer to the tabular approach.
- Description: Doctor of Philosophy
- Authors: Kurniawan, Budi
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis uses reinforcement learning (RL) to address dynamic adversarial games in the context of air combat manoeuvring simulation. A sequential decision problem commonly encountered in the field of operations research, air combat manoeuvring simulation conventionally relied on agent programming methods that required significant domain knowledge to be manually encoded into the simulation environment. These methods are appropriate for determining the effectiveness of existing tactics in different simulated scenarios. However, in order to maximise the advantages provided by new technologies (such as autonomous aircraft), new tactics will need to be discovered. A proven technique for solving sequential decision problems, RL has the potential to discover these new tactics. This thesis explores four RL approaches—tabular, deep, discrete-to-deep and multiobjective— as mechanisms for discovering new behaviours in simulations of air combat manoeuvring. Itimplements and tests several methods for each approach and compares those methods in terms of the learning time, baseline and comparative performances, and implementation complexity. In addition to evaluating the utility of existing approaches to the specific task of air combat manoeuvring, this thesis proposes and investigates two novel methods, discrete-to-deep supervised policy learning (D2D-SPL) and discrete-to-deep supervised Q-value learning (D2D-SQL), which can be applied more generally. D2D-SPL and D2D-SQL offer the generalisability of deep RL at a cost closer to the tabular approach.
- Description: Doctor of Philosophy
- Authors: Olson, Ashley
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text: false
- Description: A fundamental goal of biogeography is to determine how communities of species assemble. Islands offer an excellent opportunity to study community assembly because they have discrete boundaries, their species compliment can be readily quantified, and biogeographic processes operating at broad spatial scales can be separated from the effects of local interactions. Indeed, islands have contributed extensively to the development of biogeographical theory. Historically, the focus of island biogeography studies has been to predict the species richness of their communities. Yet, species richness provides no information about the ecological differences among the species that comprise a community, and thus cannot explain why different types of species do, or do not, appear in island communities. The niche of any particular species represents all of the abiotic and interspecific interactions that determine the survival of that species in a given location. Thus, a niche-based description of island communities differs from a richness-only description as it can link biogeography to the ecological interactions that ultimately drive successful colonisation and evolution on an island. However, island isolation and island area - the key predictors of species immigration and extinction, respectively - and the influence of the composition of the regional species pool have rarely been investigated for their effect on niche differences among species occupying an island. Understanding how the regional species pool, isolation and area influence niche-based diversity on islands provides an important link between biogeography and the ecological interactions that ultimately determine the composition of island communities. I used data on the island birds across Melanesian archipelagos to explore the role of biogeography in driving the niche-based structure of island communities. Specifically, I studied how the composition of the regional species pool, island isolation and island area influence: i) variation in a key functional trait (body size), ii) occupancy and saturation of niches, and iii) the phylogenetic structure of island communities. To do so, I studied three Melanesian archipelagos; the Bismarck, Solomon and Vanuatu islands, each of which represent a separate biogeographic region with a different degree of isolation from the primary source of avian colonists, mainland New Guinea. As such, the influence of oceanic dispersal barriers on the composition of the avifauna of each archipelago can be clearly distinguished. Using this model system, I demonstrate that the effects of island isolation and island area extend beyond determining the number of species on an island to influencing maximum body size, niche occupancy and the phylogenetic structure of island communities. Further, the research I describe in this thesis demonstrates that the influence of island isolation and area on the ecological and evolutionary differences among species that comprise each island community is mediated by the diversity of the regional species pool. Thus, the species observed in island communities, and the niches they occupy, may not be a product of local ecological interactions. Rather, immigration from the regional species pool may determine the persistence of a species on an island.
- Description: Doctor of Philosophy
Stella’s story : writing a fictional representation of historic poland set during the Second World War
- Authors: Clinnick, Andrew
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: For my Ph.D. Literature thesis, I have produced a historical novel titled Stella’s Story, supported by an exegesis, which explores the Polish experience of WWII. Both novel and exegesis will challenge common misconceptions as perpetuated by the popular mainstream Western media—as expressed in such works as The German New Order in Poland (1943) and God’s Playground (1981), and novels such as Sophie’s Choice (1979) and The Polish Officer (2005)—that, during WWII, Poland was a predominant white-Catholic nation, bullied by the Nazis. Instead, I demonstrate that, rather than being homogenous or a caricature of a passive victim, Poland was a diverse and multi-cultural nation, where eclectic sectors of society resisted Nazi-German rule, despite the complexities wrought by Poland’s own history of antisemitism and the threat posed by those Poles who collaborated with the Nazis. This exegesis will also examine the outsider experience and the contribution to Poland’s wartime effort by women; as well as the relationship between oral history, myth and the historical records. Finally, this exegesis will explore the methods I have used to create a historical fiction about Nazi-occupied Poland.
- Description: Doctor of Philosophy
- Authors: Clinnick, Andrew
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: For my Ph.D. Literature thesis, I have produced a historical novel titled Stella’s Story, supported by an exegesis, which explores the Polish experience of WWII. Both novel and exegesis will challenge common misconceptions as perpetuated by the popular mainstream Western media—as expressed in such works as The German New Order in Poland (1943) and God’s Playground (1981), and novels such as Sophie’s Choice (1979) and The Polish Officer (2005)—that, during WWII, Poland was a predominant white-Catholic nation, bullied by the Nazis. Instead, I demonstrate that, rather than being homogenous or a caricature of a passive victim, Poland was a diverse and multi-cultural nation, where eclectic sectors of society resisted Nazi-German rule, despite the complexities wrought by Poland’s own history of antisemitism and the threat posed by those Poles who collaborated with the Nazis. This exegesis will also examine the outsider experience and the contribution to Poland’s wartime effort by women; as well as the relationship between oral history, myth and the historical records. Finally, this exegesis will explore the methods I have used to create a historical fiction about Nazi-occupied Poland.
- Description: Doctor of Philosophy
Teaching with difference : barriers and enablers for teachers with impairments in their professional roles
- Authors: Skene, Gerrard
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Amidst the current groundswell of inclusive practices adopted in learning institutions, there would appear to be a paucity of research regarding the barriers and enablers experienced by teachers with impairments in Australian education systems (Burke, 2016; Pritchard, 2010; Sheridan & Kotevski, 2014). This thesis presents an examination of national and international literature where an imprecise range of issues for teachers with impairments is identified. The social model of disability has been adopted as the overarching theoretical perspective for this study. The conceptualisation of teaching with impairment, rather than about impairment, embodies the notion of teachers with impairments as being culturally relevant educators (Pritchard, 2010). Narrative inquiry, in conjunction with Clandinin and Connelly’s (2000) three-dimensional space approach as a thematical analysis methodology, has been employed and supports the investigation of ten teachers with impairments working in professional education roles within Australia. Narrative interviews were conducted with each of the ten participants with the aim of identifying barriers and enablers within the lived experiences of teachers with impairments. This study identified a silence in relation to teachers with impairments, and to address this silence has amplified the voices of teachers with impairments. Five primary themes emerged from the data to provide insights into barriers and enablers experienced by teachers with impairments. These themes are: Thinking about becoming a teacher; The limiting attitudes of others; Connecting with students and parents; Notions of teaching spaces; and I get by with a little help from my friends. This study found that teachers with impairments do experience adverse attitudes and biases in Australian teaching institutions despite there being laws that have been specifically designed to prevent disability discrimination. Bias, experienced as discrimination towards teachers with impairments, extends to career promotion and workplace advancement opportunities. Conversely, the study also found that respectful conversations about impairment which took place both inside and outside teaching places, highlighted how having open conversations about reasonable adjustments can lead to actions that become enablers for teachers with impairments. This study commences the important work of giving voice to teachers with impairments and creates a space to challenge dominant perspectives. The thesis concludes that more needs to be done to challenge the constructed normative attitudes that are responsible for setting teachers with impairments apart and resulting in them being mostly undetected within the teacher population; Doctor of Philosophy
- Authors: Skene, Gerrard
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Amidst the current groundswell of inclusive practices adopted in learning institutions, there would appear to be a paucity of research regarding the barriers and enablers experienced by teachers with impairments in Australian education systems (Burke, 2016; Pritchard, 2010; Sheridan & Kotevski, 2014). This thesis presents an examination of national and international literature where an imprecise range of issues for teachers with impairments is identified. The social model of disability has been adopted as the overarching theoretical perspective for this study. The conceptualisation of teaching with impairment, rather than about impairment, embodies the notion of teachers with impairments as being culturally relevant educators (Pritchard, 2010). Narrative inquiry, in conjunction with Clandinin and Connelly’s (2000) three-dimensional space approach as a thematical analysis methodology, has been employed and supports the investigation of ten teachers with impairments working in professional education roles within Australia. Narrative interviews were conducted with each of the ten participants with the aim of identifying barriers and enablers within the lived experiences of teachers with impairments. This study identified a silence in relation to teachers with impairments, and to address this silence has amplified the voices of teachers with impairments. Five primary themes emerged from the data to provide insights into barriers and enablers experienced by teachers with impairments. These themes are: Thinking about becoming a teacher; The limiting attitudes of others; Connecting with students and parents; Notions of teaching spaces; and I get by with a little help from my friends. This study found that teachers with impairments do experience adverse attitudes and biases in Australian teaching institutions despite there being laws that have been specifically designed to prevent disability discrimination. Bias, experienced as discrimination towards teachers with impairments, extends to career promotion and workplace advancement opportunities. Conversely, the study also found that respectful conversations about impairment which took place both inside and outside teaching places, highlighted how having open conversations about reasonable adjustments can lead to actions that become enablers for teachers with impairments. This study commences the important work of giving voice to teachers with impairments and creates a space to challenge dominant perspectives. The thesis concludes that more needs to be done to challenge the constructed normative attitudes that are responsible for setting teachers with impairments apart and resulting in them being mostly undetected within the teacher population; Doctor of Philosophy
The association of circular RNAs with hypertension
- Authors: Woods, Bradley
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis contains six chapters in total with chapter 1 being a literature overview and chapter 2 being a summary of material and methods. The three results chapters contain all my own work unless stated otherwise and lastly chapter 6 is discussion and conclusions linking together the work undertaken in this thesis.
- Description: Doctor of Philosophy
- Authors: Woods, Bradley
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis contains six chapters in total with chapter 1 being a literature overview and chapter 2 being a summary of material and methods. The three results chapters contain all my own work unless stated otherwise and lastly chapter 6 is discussion and conclusions linking together the work undertaken in this thesis.
- Description: Doctor of Philosophy