Vulnerability modelling and mitigation strategies for hybrid networks
- Authors: Ur-Rehman, Attiq
- Date: 2023
- Type: Text , Thesis , PhD
- Full Text:
- Description: Hybrid networks nowadays consist of traditional IT components, Internet of Things (IoT) and industrial control systems (ICS) nodes with varying characteristics, making them genuinely heterogeneous in nature. Historically evolving from traditional internet-enabled IT servers, hybrid networks allow organisations to strengthen cybersecurity, increase flexibility, improve efficiency, enhance reliability, boost remote connectivity and easy management. Though hybrid networks offer significant benefits from business and operational perspectives, this integration has increased the complexity and security challenges to all connected nodes. The IT servers of these hybrid networks are high-budget devices with tremendous processing power and significant storage capacity. In contrast, IoT nodes are low-cost devices with limited processing power and capacity. In addition, the ICS nodes are programmed for dedicated functions with the least interference. The available cybersecurity solutions for hybrid networks are either for specific node types or address particular weaknesses. Due to these distinct characteristics, these solutions may place other nodes in vulnerable positions. This study addresses this gap by proposing a comprehensive vulnerability modelling and mitigation strategy. This proposed solution equally applies to each node type of hybrid network while considering their unique characteristics. For this purpose, the industry-wide adoption of the Common Vulnerability Scoring System (CVSS) has been extended to embed the distinct characteristics of each node type in a hybrid network. To embed IoT features, the ‘attack vectors’ and ‘attack complexity vectors’ are modified and another metric “human safety index”, is integrated in the ‘Base metric group’ of CVSS. In addition, the ICS related characteristics are included in the ‘Environmental metric group’ of CVSS. This metric group is further enhanced to reflect the node resilience capabilities when evaluating the vulnerability score. The resilience of a node is evaluated by analysing the complex relationship of numerous contributing cyber security factors and practices. The evolved CVSSR-IoT-ICS framework proposed in the thesis measures the given vulnerabilities by adopting the unique dynamics of each node. These vulnerability scores are then mapped in the attack tree to reveal the critical nodes and shortest path to the target node. The mitigating strategy framework suggests the most efficient mitigation strategy to counter vulnerabilities by examining the node’s functionality, its locality, centrality, criticality, cascading impacts, available resources, and performance thresholds. Various case studies were conducted to analyse and evaluate our proposed vulnerability modelling and mitigation strategies on realistic supply chain systems. These analyses and evaluations confirm that the proposed solutions are highly effective for modelling the vulnerabilities while the mitigation strategies reduce the risks in dynamic and resource-constrained environments. The unified vulnerability modelling of hybrid networks minimises ambiguities, reduces complexities and identifies hidden deficiencies. It also improves system reliability and performance of heterogeneous networks while at the same time gaining acceptance for a universal vulnerability modelling framework across the cyber industry. The contributions have been published in reputable journals and conferences.
- Description: Doctor of Philosophy
- Authors: Ur-Rehman, Attiq
- Date: 2023
- Type: Text , Thesis , PhD
- Full Text:
- Description: Hybrid networks nowadays consist of traditional IT components, Internet of Things (IoT) and industrial control systems (ICS) nodes with varying characteristics, making them genuinely heterogeneous in nature. Historically evolving from traditional internet-enabled IT servers, hybrid networks allow organisations to strengthen cybersecurity, increase flexibility, improve efficiency, enhance reliability, boost remote connectivity and easy management. Though hybrid networks offer significant benefits from business and operational perspectives, this integration has increased the complexity and security challenges to all connected nodes. The IT servers of these hybrid networks are high-budget devices with tremendous processing power and significant storage capacity. In contrast, IoT nodes are low-cost devices with limited processing power and capacity. In addition, the ICS nodes are programmed for dedicated functions with the least interference. The available cybersecurity solutions for hybrid networks are either for specific node types or address particular weaknesses. Due to these distinct characteristics, these solutions may place other nodes in vulnerable positions. This study addresses this gap by proposing a comprehensive vulnerability modelling and mitigation strategy. This proposed solution equally applies to each node type of hybrid network while considering their unique characteristics. For this purpose, the industry-wide adoption of the Common Vulnerability Scoring System (CVSS) has been extended to embed the distinct characteristics of each node type in a hybrid network. To embed IoT features, the ‘attack vectors’ and ‘attack complexity vectors’ are modified and another metric “human safety index”, is integrated in the ‘Base metric group’ of CVSS. In addition, the ICS related characteristics are included in the ‘Environmental metric group’ of CVSS. This metric group is further enhanced to reflect the node resilience capabilities when evaluating the vulnerability score. The resilience of a node is evaluated by analysing the complex relationship of numerous contributing cyber security factors and practices. The evolved CVSSR-IoT-ICS framework proposed in the thesis measures the given vulnerabilities by adopting the unique dynamics of each node. These vulnerability scores are then mapped in the attack tree to reveal the critical nodes and shortest path to the target node. The mitigating strategy framework suggests the most efficient mitigation strategy to counter vulnerabilities by examining the node’s functionality, its locality, centrality, criticality, cascading impacts, available resources, and performance thresholds. Various case studies were conducted to analyse and evaluate our proposed vulnerability modelling and mitigation strategies on realistic supply chain systems. These analyses and evaluations confirm that the proposed solutions are highly effective for modelling the vulnerabilities while the mitigation strategies reduce the risks in dynamic and resource-constrained environments. The unified vulnerability modelling of hybrid networks minimises ambiguities, reduces complexities and identifies hidden deficiencies. It also improves system reliability and performance of heterogeneous networks while at the same time gaining acceptance for a universal vulnerability modelling framework across the cyber industry. The contributions have been published in reputable journals and conferences.
- Description: Doctor of Philosophy
Accurate prediction of sewer network flows and assessment of groundwater infiltration volumes in sewer networks
- Authors: Jayasooriya, Mahinda
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Excessive flows due to inflow and infiltration (I&I) in sewer networks contribute to hydraulically overloaded sanitary sewer networks. Understanding the cause–effect relationships associated with sewer network flow generation and accurate quantification of excessive flow volumes entering sewer networks is crucial to developing solutions to resolve this issue. A systematic literature review found a gap in understanding the cause–effect relationships of I&I and no universally accepted method for I&I estimation. This research used three years of data from an Australian sewer catchment in Ballarat, Victoria, as a case study to enhance understanding of the network flow generation process. The aims of this research were to accurately predict sewer network flows, reliably separate the groundwater infiltration (GWI) volume of sewer network flow, improve understanding of associated processes and identify the influential parameters that impact sewer network flow. This research used three methods to achieve these aims. First, commercially available software was used to develop and calibrate a sewer network model to predict flows with data from the case study catchment. The best practice guidelines available in Australia were used to calibrate the model, and a new method was introduced to separate the sewer network flow components. Second, two classical hydrology applications, the recursive filter and the flow duration curve (FDC) methods, were used to separate the GWI component of the total sewer network flow and understand the performance of the sewer catchments. Third, an artificial neural network (ANN) model was developed to predict sewer network flow. Parameters known to influence sewer flows were incrementally introduced to the ANN model to improve performance and understand their relative importance. This study finds that commercially available software can predict total sewer network flows with reasonable accuracy using the Wallingford or triangular hydrograph (RTK) hydrological implementation methods. However, the software cannot replicate the dynamic nature of the complex I&I processes that occur over time or reliably separate the sewer network flow components. A key finding from this study is that commercially available software has clear limitations in separating sewer network flow components. Recursive filter and FDC methods can be successfully used as standalone techniques to calculate the GWI volume. These methods have further value in comparing the I&I between catchments to determine flow characteristics and are straightforward for practising engineers to use. The ANN model predicts sewer flow with a high level of accuracy, and soil moisture is the most critical predictor of the total flow regime. The ANN model is also able to predict the dynamic and complex nature of I&I into sewer networks. More research is needed to achieve effective and reliable separation of individual components in an overall sewer flow regime. ANN and other emerging machine learning techniques show much potential to effectively predict sewer flows across a range of sewer network and catchment characteristics.
- Description: Doctor of Philosophy
- Authors: Jayasooriya, Mahinda
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Excessive flows due to inflow and infiltration (I&I) in sewer networks contribute to hydraulically overloaded sanitary sewer networks. Understanding the cause–effect relationships associated with sewer network flow generation and accurate quantification of excessive flow volumes entering sewer networks is crucial to developing solutions to resolve this issue. A systematic literature review found a gap in understanding the cause–effect relationships of I&I and no universally accepted method for I&I estimation. This research used three years of data from an Australian sewer catchment in Ballarat, Victoria, as a case study to enhance understanding of the network flow generation process. The aims of this research were to accurately predict sewer network flows, reliably separate the groundwater infiltration (GWI) volume of sewer network flow, improve understanding of associated processes and identify the influential parameters that impact sewer network flow. This research used three methods to achieve these aims. First, commercially available software was used to develop and calibrate a sewer network model to predict flows with data from the case study catchment. The best practice guidelines available in Australia were used to calibrate the model, and a new method was introduced to separate the sewer network flow components. Second, two classical hydrology applications, the recursive filter and the flow duration curve (FDC) methods, were used to separate the GWI component of the total sewer network flow and understand the performance of the sewer catchments. Third, an artificial neural network (ANN) model was developed to predict sewer network flow. Parameters known to influence sewer flows were incrementally introduced to the ANN model to improve performance and understand their relative importance. This study finds that commercially available software can predict total sewer network flows with reasonable accuracy using the Wallingford or triangular hydrograph (RTK) hydrological implementation methods. However, the software cannot replicate the dynamic nature of the complex I&I processes that occur over time or reliably separate the sewer network flow components. A key finding from this study is that commercially available software has clear limitations in separating sewer network flow components. Recursive filter and FDC methods can be successfully used as standalone techniques to calculate the GWI volume. These methods have further value in comparing the I&I between catchments to determine flow characteristics and are straightforward for practising engineers to use. The ANN model predicts sewer flow with a high level of accuracy, and soil moisture is the most critical predictor of the total flow regime. The ANN model is also able to predict the dynamic and complex nature of I&I into sewer networks. More research is needed to achieve effective and reliable separation of individual components in an overall sewer flow regime. ANN and other emerging machine learning techniques show much potential to effectively predict sewer flows across a range of sewer network and catchment characteristics.
- Description: Doctor of Philosophy
Adapting port cluster theory to contextualise the remarkable rise of the gold rushes port of Melbourne: 1851–1861
- Authors: Taylor, Peter
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The research question that forms the basis of this thesis asks how and what drove the port of Melbourne to advance 30–50 years growth in less than ten during the 1850s gold era. To answer this question this thesis modifies and tests a new methodological approach to read the port’s growth driven by a close reading and evaluation of port cluster theory. Developed in the early 2000s the theory synthesises elements that constitute a port and operations through a wide range of components and activities. Recognising that a twenty-first-century port is not the same as a mid-nineteenth-century port, through advances brought on by a wide range of modern technologies, the theory has been historicised to dismantle the 1851–1861 gold era port of Melbourne to recognise its parts and how it was built. One of the tools to be enhanced and expanded for this is the cluster table of components and activities, providing specifics for activities undertaken at a mid-nineteenth-century port. A key constituent this propels the research forward when applied at Melbourne’s four ports of central Melbourne, Sandridge (Port Melbourne), Williamstown, Footscray and the Saltwater (Maribyrnong) River (combined). The argument is made that the ports evolved to be a port cluster reinforced by the exploration of specific themes of defence, security, river punts, entrepreneurs, ballast trade, quarrying, railways, noxious industries, shipwreck salvage, shipbuilding, ship repairs, tourism and wharf construction as topics. This thesis then uses the evidence gained to claim that the port did indeed evolve into a cluster port by 1861. The wider implication of this research is that a new framework exists for understanding the complexities of a mid-nineteenth-century port and how this can be done in a systematic way. For this methodology to demonstrate utility outside the port of Melbourne, requires further testing at sites within Australia, and worldwide, for confirmation of universality.
- Description: Doctor of Philosophy
- Authors: Taylor, Peter
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: The research question that forms the basis of this thesis asks how and what drove the port of Melbourne to advance 30–50 years growth in less than ten during the 1850s gold era. To answer this question this thesis modifies and tests a new methodological approach to read the port’s growth driven by a close reading and evaluation of port cluster theory. Developed in the early 2000s the theory synthesises elements that constitute a port and operations through a wide range of components and activities. Recognising that a twenty-first-century port is not the same as a mid-nineteenth-century port, through advances brought on by a wide range of modern technologies, the theory has been historicised to dismantle the 1851–1861 gold era port of Melbourne to recognise its parts and how it was built. One of the tools to be enhanced and expanded for this is the cluster table of components and activities, providing specifics for activities undertaken at a mid-nineteenth-century port. A key constituent this propels the research forward when applied at Melbourne’s four ports of central Melbourne, Sandridge (Port Melbourne), Williamstown, Footscray and the Saltwater (Maribyrnong) River (combined). The argument is made that the ports evolved to be a port cluster reinforced by the exploration of specific themes of defence, security, river punts, entrepreneurs, ballast trade, quarrying, railways, noxious industries, shipwreck salvage, shipbuilding, ship repairs, tourism and wharf construction as topics. This thesis then uses the evidence gained to claim that the port did indeed evolve into a cluster port by 1861. The wider implication of this research is that a new framework exists for understanding the complexities of a mid-nineteenth-century port and how this can be done in a systematic way. For this methodology to demonstrate utility outside the port of Melbourne, requires further testing at sites within Australia, and worldwide, for confirmation of universality.
- Description: Doctor of Philosophy
An evaluation of the effectiveness of a consumer-led educational program about stigma in mental illness and recovery attitudes among Mental Health Nurses
- Authors: Sreeram, Anju
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Fear, frustration and myths about mental illness engenders negative attitudes towards mental illness. Such negative attitudes impede the recovery of people diagnosed with mental illness. Despite an increasing emphasis on stigma and recovery-focused practices, evidence shows prejudicial attitudes towards mental illness and the recovery of people with mental illness among mental health professionals still exist. Anti-stigma initiatives and recovery-oriented interventions can aid in enhancing the attitudes of mental health professionals. Contact-based interventions have the greatest impact on attitudes among the mental health professionals including nurses. However, research regarding initiatives targeting stigma of mental illness and recovery attitudes among Mental Health Nurses working in the acute inpatient psychiatric units is limited. Therefore, the aim of the current study was to evaluate the effectiveness of a consumer-led education package on stigma about mental illness and recovery attitudes of Mental Health Nurses. A sequential explanatory mixed-method, with a pre-test and post-test design was used to evaluate the effect of consumer-led education. This research involved three phases. In the first phase, the study explored Mental Health Nurses' attitudes towards mental illness and recovery using surveys and non-participant observation. The second phase focused on the co-development and co-implementation of a consumer-led education package. The effectiveness of the intervention was evaluated using immediate post-test assessment and again three months later. The final phase focused on exploring the results obtained in the first and second phases of the study through an in-depth interview.
- Description: Doctor of Philosophy
- Authors: Sreeram, Anju
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Fear, frustration and myths about mental illness engenders negative attitudes towards mental illness. Such negative attitudes impede the recovery of people diagnosed with mental illness. Despite an increasing emphasis on stigma and recovery-focused practices, evidence shows prejudicial attitudes towards mental illness and the recovery of people with mental illness among mental health professionals still exist. Anti-stigma initiatives and recovery-oriented interventions can aid in enhancing the attitudes of mental health professionals. Contact-based interventions have the greatest impact on attitudes among the mental health professionals including nurses. However, research regarding initiatives targeting stigma of mental illness and recovery attitudes among Mental Health Nurses working in the acute inpatient psychiatric units is limited. Therefore, the aim of the current study was to evaluate the effectiveness of a consumer-led education package on stigma about mental illness and recovery attitudes of Mental Health Nurses. A sequential explanatory mixed-method, with a pre-test and post-test design was used to evaluate the effect of consumer-led education. This research involved three phases. In the first phase, the study explored Mental Health Nurses' attitudes towards mental illness and recovery using surveys and non-participant observation. The second phase focused on the co-development and co-implementation of a consumer-led education package. The effectiveness of the intervention was evaluated using immediate post-test assessment and again three months later. The final phase focused on exploring the results obtained in the first and second phases of the study through an in-depth interview.
- Description: Doctor of Philosophy
An investigation of heat stress epidemiology, prevention guidelines, and sporting environment
- Authors: Gonsalves, Marlon
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: As temperatures rise, the frequency of heatwaves, extreme summer heat and less night-time cooling increases. An uncontrolled increase in heat production affects performance and subsequently affects the health of the athlete resulting in exertional heat illness (EHI). EHI is a result of an uncontrollable rise in core body temperature arising from a thermoregulatory response. With rising temperatures, the risk of EHI when exercising or participating in sport increases. However, assessing the risk of EHI is contingent on accurate epidemiological data and addressing the risk of EHI is reliant on effective evidence-based interventions. This thesis assessed the risk of EHI through four interlinked studies: (ⅰ) an analysis of heat-related sports and leisure hospitalisations and emergency department presentations to determine trends in incidence rates and compare them with meteorological trends; (ⅱ) a document analysis of all sports and leisure activity heat-related injury prevention resources in Australia to develop an understanding of the content within those resources; (ⅲ) an investigation of surface temperatures of commonly used artificial sports surfaces to assess the risk posed by such surfaces and measure the differences in microclimates; and, (ⅳ) an assessment of the concordance of meteorological data of multiple artificial sports surfaces with meteorological data from the nearest Bureau of Meteorology (BOM) weather station and a local City of Ballarat (COB) environmental monitoring system (EMS). A total of 1055 heat injury hospitalisations and emergency department (ED) presentations were recorded between July 2008 and June 2018, which included 171 sport-related hospitalisations,139 ED presentations, 83 leisure-related hospitalisations and 662 ED presentations. There were significant correlations between ED presentations for heat-related sports injuries and mean, minimum and maximum temperature, mean and maximum temperature anomaly, summer maximum temperature, and summer maximum temperature anomaly. Three overarching categories emerged through the document analysis process: preventive strategies (n=299, 63.9%), risk factors (n=94, 20.1%), and treatment (n=75, 16.0%). Activity modification, which included information on rescheduling games and extra breaks, was the most common intervention. Cricket, soccer, swimming, and triathlon had the most complete set of heat resources. During the 2020–2021 summer period a total of 1245 measurements were recorded across five artificial sports surfaces: athletics, hockey, lawn bowls, soccer, tennis. The lawn bowls turf was the hottest surface with a mean surface temperature of 54.43 (± 13.46) °C. An increase in surface temperature corresponded to an increase in air temperature, wet bulb temperature and a decrease in relative humidity but the effect varied across the five surfaces. An increase in solar radiation and air temperature also corresponded to an increase in surface temperature. On all five surfaces measured, the BOM air temperatures were the lowest, followed by the on-site air temperatures and then the COB air temperatures on all surfaces. The highest Wet Bulb Globe Temperature (WBGT) measurements of 24.38 (± 2.39) °C were recorded by the COB sensor, while the lowest WBGT measurements 20.76 (± 1.99) °C were recorded by the BOM. There was a statistically significant difference in the WBGT categorisation between on-site estimate measurements and BOM measurements, p <0.001. The incidence of heat-related hospitalisations and ED presentations provides a baseline from which heat-related guidelines and interventions can be developed, evaluated, and modified. Heat resources considered in the document analysis suggest EHI is preventable if appropriate precautions are implemented. With a focus on preventing EHI, heat resources mainly provided recommendations on modifying activities and reducing exposure to extreme conditions. These results imply the EHI risk posed by artificial sport surfaces are not uniform and safety polices should be updated to reflect the link between air temperature and surface temperature. Understanding how surface temperature is influenced by air temperature, solar radiation and cloud cover allows for more accurate predictions of playing conditions on these artificial sport surfaces. Differences were observed between the individual meteorological measurements, the WBGT measurements and the heat stress categorisation. Overall, a significant discord existed for both individual meteorological variables and WBGT modelled from multiple sources of available data. The findings from this thesis have implications for athlete welfare and strengthening future interventions. Overall, this doctoral research project quantifies the scale of heat-related injuries, reviews the policies to address these heat-related injuries and provides new knowledge on the risk posed by artificial sports surfaces.
- Description: Doctor of Philosophy
- Description: As temperatures rise, the frequency of heatwaves, extreme summer heat and less night-time cooling increases. An uncontrolled increase in heat production affects performance and subsequently affects the health of the athlete resulting in exertional heat illness (EHI). EHI is a result of an uncontrollable rise in core body temperature arising from a thermoregulatory response. With rising temperatures, the risk of EHI when exercising or participating in sport increases. However, assessing the risk of EHI is contingent on accurate epidemiological data and addressing the risk of EHI is reliant on effective evidence-based interventions. This thesis assessed the risk of EHI through four interlinked studies: (
- Authors: Gonsalves, Marlon
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: As temperatures rise, the frequency of heatwaves, extreme summer heat and less night-time cooling increases. An uncontrolled increase in heat production affects performance and subsequently affects the health of the athlete resulting in exertional heat illness (EHI). EHI is a result of an uncontrollable rise in core body temperature arising from a thermoregulatory response. With rising temperatures, the risk of EHI when exercising or participating in sport increases. However, assessing the risk of EHI is contingent on accurate epidemiological data and addressing the risk of EHI is reliant on effective evidence-based interventions. This thesis assessed the risk of EHI through four interlinked studies: (ⅰ) an analysis of heat-related sports and leisure hospitalisations and emergency department presentations to determine trends in incidence rates and compare them with meteorological trends; (ⅱ) a document analysis of all sports and leisure activity heat-related injury prevention resources in Australia to develop an understanding of the content within those resources; (ⅲ) an investigation of surface temperatures of commonly used artificial sports surfaces to assess the risk posed by such surfaces and measure the differences in microclimates; and, (ⅳ) an assessment of the concordance of meteorological data of multiple artificial sports surfaces with meteorological data from the nearest Bureau of Meteorology (BOM) weather station and a local City of Ballarat (COB) environmental monitoring system (EMS). A total of 1055 heat injury hospitalisations and emergency department (ED) presentations were recorded between July 2008 and June 2018, which included 171 sport-related hospitalisations,139 ED presentations, 83 leisure-related hospitalisations and 662 ED presentations. There were significant correlations between ED presentations for heat-related sports injuries and mean, minimum and maximum temperature, mean and maximum temperature anomaly, summer maximum temperature, and summer maximum temperature anomaly. Three overarching categories emerged through the document analysis process: preventive strategies (n=299, 63.9%), risk factors (n=94, 20.1%), and treatment (n=75, 16.0%). Activity modification, which included information on rescheduling games and extra breaks, was the most common intervention. Cricket, soccer, swimming, and triathlon had the most complete set of heat resources. During the 2020–2021 summer period a total of 1245 measurements were recorded across five artificial sports surfaces: athletics, hockey, lawn bowls, soccer, tennis. The lawn bowls turf was the hottest surface with a mean surface temperature of 54.43 (± 13.46) °C. An increase in surface temperature corresponded to an increase in air temperature, wet bulb temperature and a decrease in relative humidity but the effect varied across the five surfaces. An increase in solar radiation and air temperature also corresponded to an increase in surface temperature. On all five surfaces measured, the BOM air temperatures were the lowest, followed by the on-site air temperatures and then the COB air temperatures on all surfaces. The highest Wet Bulb Globe Temperature (WBGT) measurements of 24.38 (± 2.39) °C were recorded by the COB sensor, while the lowest WBGT measurements 20.76 (± 1.99) °C were recorded by the BOM. There was a statistically significant difference in the WBGT categorisation between on-site estimate measurements and BOM measurements, p <0.001. The incidence of heat-related hospitalisations and ED presentations provides a baseline from which heat-related guidelines and interventions can be developed, evaluated, and modified. Heat resources considered in the document analysis suggest EHI is preventable if appropriate precautions are implemented. With a focus on preventing EHI, heat resources mainly provided recommendations on modifying activities and reducing exposure to extreme conditions. These results imply the EHI risk posed by artificial sport surfaces are not uniform and safety polices should be updated to reflect the link between air temperature and surface temperature. Understanding how surface temperature is influenced by air temperature, solar radiation and cloud cover allows for more accurate predictions of playing conditions on these artificial sport surfaces. Differences were observed between the individual meteorological measurements, the WBGT measurements and the heat stress categorisation. Overall, a significant discord existed for both individual meteorological variables and WBGT modelled from multiple sources of available data. The findings from this thesis have implications for athlete welfare and strengthening future interventions. Overall, this doctoral research project quantifies the scale of heat-related injuries, reviews the policies to address these heat-related injuries and provides new knowledge on the risk posed by artificial sports surfaces.
- Description: Doctor of Philosophy
- Description: As temperatures rise, the frequency of heatwaves, extreme summer heat and less night-time cooling increases. An uncontrolled increase in heat production affects performance and subsequently affects the health of the athlete resulting in exertional heat illness (EHI). EHI is a result of an uncontrollable rise in core body temperature arising from a thermoregulatory response. With rising temperatures, the risk of EHI when exercising or participating in sport increases. However, assessing the risk of EHI is contingent on accurate epidemiological data and addressing the risk of EHI is reliant on effective evidence-based interventions. This thesis assessed the risk of EHI through four interlinked studies: (
Are nurse academics technology ready? A mixed methods study of Australian nurse academics’ attitudes to technologies in teaching
- Authors: Browning, Mark
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Technology use in higher education teaching has become widespread and ubiquitous, affecting many areas of teaching and learning (Bond et al., 2020). Nurse education has been impacted by this shift with increasing use of technologies in the classroom (Koch, 2014). Although there has been a large research focus relating to students’ elearning, there has been less focus on the academic and their elearning role, in particular, how academic attitudes influence technology use in teaching (Drysdale et al., 2013; Martin, Polly, et al., 2020). The aim of this study was to explore nurse academics’ attitudes to technology and the influence attitude has on their use of technologies in teaching. There were three objectives: 1) To investigate nurse academics’ attitudes to technology through the Technology Readiness Index 2.0 (TRI 2). 2) To develop an understanding of how and why nurse academics engage with technology through individual interviews. 3) To integrate the quantitative (Objective 1) and qualitative (Objective 2) findings in order to gain a holistic understanding of academics’ use of technologies in teaching. A mixed methods sequential explanatory design consisting of two phases was used to address the aim. The first phase was a survey based on a previously validated, 16 item questionnaire, the Technology Readiness Index 2.0 (TRI 2), which was distributed to Australian nurse academics. The second phase included semi-structured individual interviews focussed on academics’ use and attitudes to technology, incorporating elements from the survey. The Technology Readiness Index 2.0 (TRI 2) was used in this study for the first time with nurse academics. The phase one findings indicate that nurse academics were technology ready, had higher overall TRI mean score than the general population (Parasuraman & Colby, 2015), but with similar outcomes to previous nurse academic research. Of note was that TRI was significantly associated with frequency of technology use, number of technologies used and self-rated confidence to use technology. The findings revealed three main Technology Readiness groups, representing three attitudes to technology in teaching: Explorers, Sceptics and Hesitators. Explorers were found to be innovative, positive and confident in their use of technology; Sceptics showed aversion to technology, were cautious when considering the impact on pedagogy and concerned about the impact on interpersonal skills; Hesitators showed preference for traditional teaching and distrust and were anxious about technology use. Overall, attitudes were found to be complex, based on experience and the potential impact technology may have on nursing students. The groups identified in this thesis explain behaviours and enable institutes to support academics in their engagement with technology. Recommendations include flexible training to meet the needs of academics, the use of simple and reliable technology across TR groups and adjusting workloads to account for the time-consuming nature of technology. There is also a need for academics to consider their attitudes to technology and the impact this may have on their teaching. This thesis demonstrates that technology engagement is not a binary choice but a complex process based on attitudes and other factors.
- Description: Doctor of Philosophy
- Authors: Browning, Mark
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Technology use in higher education teaching has become widespread and ubiquitous, affecting many areas of teaching and learning (Bond et al., 2020). Nurse education has been impacted by this shift with increasing use of technologies in the classroom (Koch, 2014). Although there has been a large research focus relating to students’ elearning, there has been less focus on the academic and their elearning role, in particular, how academic attitudes influence technology use in teaching (Drysdale et al., 2013; Martin, Polly, et al., 2020). The aim of this study was to explore nurse academics’ attitudes to technology and the influence attitude has on their use of technologies in teaching. There were three objectives: 1) To investigate nurse academics’ attitudes to technology through the Technology Readiness Index 2.0 (TRI 2). 2) To develop an understanding of how and why nurse academics engage with technology through individual interviews. 3) To integrate the quantitative (Objective 1) and qualitative (Objective 2) findings in order to gain a holistic understanding of academics’ use of technologies in teaching. A mixed methods sequential explanatory design consisting of two phases was used to address the aim. The first phase was a survey based on a previously validated, 16 item questionnaire, the Technology Readiness Index 2.0 (TRI 2), which was distributed to Australian nurse academics. The second phase included semi-structured individual interviews focussed on academics’ use and attitudes to technology, incorporating elements from the survey. The Technology Readiness Index 2.0 (TRI 2) was used in this study for the first time with nurse academics. The phase one findings indicate that nurse academics were technology ready, had higher overall TRI mean score than the general population (Parasuraman & Colby, 2015), but with similar outcomes to previous nurse academic research. Of note was that TRI was significantly associated with frequency of technology use, number of technologies used and self-rated confidence to use technology. The findings revealed three main Technology Readiness groups, representing three attitudes to technology in teaching: Explorers, Sceptics and Hesitators. Explorers were found to be innovative, positive and confident in their use of technology; Sceptics showed aversion to technology, were cautious when considering the impact on pedagogy and concerned about the impact on interpersonal skills; Hesitators showed preference for traditional teaching and distrust and were anxious about technology use. Overall, attitudes were found to be complex, based on experience and the potential impact technology may have on nursing students. The groups identified in this thesis explain behaviours and enable institutes to support academics in their engagement with technology. Recommendations include flexible training to meet the needs of academics, the use of simple and reliable technology across TR groups and adjusting workloads to account for the time-consuming nature of technology. There is also a need for academics to consider their attitudes to technology and the impact this may have on their teaching. This thesis demonstrates that technology engagement is not a binary choice but a complex process based on attitudes and other factors.
- Description: Doctor of Philosophy
Continuing professional development of allied health professionals : A regional study
- Authors: Schenk, Peter
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Background The Australian healthcare system is challenged by an ageing population and lifestyle risk factors that disproportionately affect people in regional (non-metropolitan) geographic regions. In addition, the allied health professionals who work in knowledge-intensive occupations in regional Victoria face barriers regarding profession related learning. Allied health professionals provide diagnostic and therapeutic patient care services, and within these professions, healthcare diagnoses and treatments are expected by society and government to be founded on scientific evidence. Therefore, remaining up-to-date with rapidly developing knowledge requires continuing professional development (CPD). Purpose This study explores pertinent issues affecting the CPD programs of allied health professionals and the interaction with regional Victorian public hospitals’ knowledge management (KM) approaches. Consequently, the study identifies opportunities for improving profession related learning, enhancing evidence-based practice and the efficacy of diagnoses and treatments. The proposed outcome of this study addresses perceived inadequacies of allied health professionals’ CPD and its contribution to medical errors. Furthermore, greater availability and effectiveness of profession related learning in these occupations should improve patients’ health outcomes. The study described in this thesis answers the primary research question: 1) What factors significantly influence the availability and effectiveness of continuing professional development (CPD) for allied health professionals (radiographers, sonographers and physiotherapists)? In addition, it also answers the secondary research question: 2) How can the findings of this research be represented to improve the CPD of allied health professionals and knowledge management (KM) in regional Victorian public hospitals? Methodology This study explores subjective phenomena involving human behaviour; therefore, the philosophical foundations of this study are post-positivist, with knowledge claims of interpretivist research. This research employs multi-site embedded case studies, defined as empirical enquiries investigating contemporary phenomena in real-world contexts. Therefore, they are suitable for this investigation, where participant experiences and contexts are equally important. Case selection in this study expresses regionalism through remoteness classifications of inner and outer regional areas, and hospital size comparing small/medium and large/referral regional hospitals. The 37 respondents to semi-structured interviews include hospital managers and purposefully selected allied health professionals (radiographers, sonographers and physiotherapists). The interviews were conducted from March to June 2017, with thematic analysis completed thereafter. Results Respondents in this study propose a holistic concept of CPD, encompassing all profession related learning opportunities, including learning from CPD activities and practice-based learning. Furthermore, the allied health professionals had various motivations for undertaking CPD, including maintaining and enhancing profession related knowledge, personal interest, supporting hospital needs, and meeting mandatory requirements. In addition, they discussed the factors that influenced their CPD planning, including their preference for formal face-to-face CPD activities, the availability of hospital-provided or local CPD activities, online learning, and overcoming barriers of their regional location. Finally, the factors influencing allied health professionals’ CPD include their planning of CPD programs, the influence of hospitals’ KM, and the competencies they consider necessary for good practice. Conclusion The thematic analysis in this study represents this study’s findings as a normative conceptual model in answer to the secondary research question. The Model of Allied Health Professionals’ CPD (described in section 6.7) proffers a heuristic framework depicting reflective feedback and the process of deliberative planning of CPD. Extrapolating knowledge from the literature and respondents’ experiences with CPD, the model’s elements include interrelationships between allied health professionals’ CPD planning and activities, hospitals’ approaches to KM, and informal workplace learning. Furthermore, the combined outcomes of CPD and KM contribute to allied health professionals’ competencies and expertise, presumably contributing to improving patients’ healthcare, including diagnoses and treatments.
- Description: Doctor of Philosophy
- Authors: Schenk, Peter
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Background The Australian healthcare system is challenged by an ageing population and lifestyle risk factors that disproportionately affect people in regional (non-metropolitan) geographic regions. In addition, the allied health professionals who work in knowledge-intensive occupations in regional Victoria face barriers regarding profession related learning. Allied health professionals provide diagnostic and therapeutic patient care services, and within these professions, healthcare diagnoses and treatments are expected by society and government to be founded on scientific evidence. Therefore, remaining up-to-date with rapidly developing knowledge requires continuing professional development (CPD). Purpose This study explores pertinent issues affecting the CPD programs of allied health professionals and the interaction with regional Victorian public hospitals’ knowledge management (KM) approaches. Consequently, the study identifies opportunities for improving profession related learning, enhancing evidence-based practice and the efficacy of diagnoses and treatments. The proposed outcome of this study addresses perceived inadequacies of allied health professionals’ CPD and its contribution to medical errors. Furthermore, greater availability and effectiveness of profession related learning in these occupations should improve patients’ health outcomes. The study described in this thesis answers the primary research question: 1) What factors significantly influence the availability and effectiveness of continuing professional development (CPD) for allied health professionals (radiographers, sonographers and physiotherapists)? In addition, it also answers the secondary research question: 2) How can the findings of this research be represented to improve the CPD of allied health professionals and knowledge management (KM) in regional Victorian public hospitals? Methodology This study explores subjective phenomena involving human behaviour; therefore, the philosophical foundations of this study are post-positivist, with knowledge claims of interpretivist research. This research employs multi-site embedded case studies, defined as empirical enquiries investigating contemporary phenomena in real-world contexts. Therefore, they are suitable for this investigation, where participant experiences and contexts are equally important. Case selection in this study expresses regionalism through remoteness classifications of inner and outer regional areas, and hospital size comparing small/medium and large/referral regional hospitals. The 37 respondents to semi-structured interviews include hospital managers and purposefully selected allied health professionals (radiographers, sonographers and physiotherapists). The interviews were conducted from March to June 2017, with thematic analysis completed thereafter. Results Respondents in this study propose a holistic concept of CPD, encompassing all profession related learning opportunities, including learning from CPD activities and practice-based learning. Furthermore, the allied health professionals had various motivations for undertaking CPD, including maintaining and enhancing profession related knowledge, personal interest, supporting hospital needs, and meeting mandatory requirements. In addition, they discussed the factors that influenced their CPD planning, including their preference for formal face-to-face CPD activities, the availability of hospital-provided or local CPD activities, online learning, and overcoming barriers of their regional location. Finally, the factors influencing allied health professionals’ CPD include their planning of CPD programs, the influence of hospitals’ KM, and the competencies they consider necessary for good practice. Conclusion The thematic analysis in this study represents this study’s findings as a normative conceptual model in answer to the secondary research question. The Model of Allied Health Professionals’ CPD (described in section 6.7) proffers a heuristic framework depicting reflective feedback and the process of deliberative planning of CPD. Extrapolating knowledge from the literature and respondents’ experiences with CPD, the model’s elements include interrelationships between allied health professionals’ CPD planning and activities, hospitals’ approaches to KM, and informal workplace learning. Furthermore, the combined outcomes of CPD and KM contribute to allied health professionals’ competencies and expertise, presumably contributing to improving patients’ healthcare, including diagnoses and treatments.
- Description: Doctor of Philosophy
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