Optimising water quality outcomes for complex water resource systems and water grids
- Authors: Dey, Sayani
- Date: 2023
- Type: Text , Thesis , PhD
- Full Text:
- Description: As the world progresses, water resources are likely to be subjected to much greater pressures than in the past. Even though the principal water problem revolves around inadequate and uncertain water supplies, water quality management plays an equally important role. Availability of good quality water is paramount to sustainability of human population as well as the environment. Achieving water quality and quantity objectives can be conflicting and becomes more complicated with challenges like, climate change, growing populations and changed land uses. Managing adequate water quality in a reservoir gets complicated by multiple inflows with different water quality levels often resulting in poor water quality. Hence, it is fundamental to approach this issue in a more systematic, comprehensive, and coordinated fashion. Most previous studies related to water resources management focused on water quantity and considered water quality separately. However, this research study focused on considering water quantity and quality objectives simultaneously in a single model to explore and understand the relationship between them in a reservoir system. A case study area was identified in Western Victoria, Australia with water quantity and quality challenges. Taylors Lake of Grampians System in Victoria, Australia receives water from multiple sources of differing quality and quantity and has the abovesaid problems. A combined simulation and optimisation approach was adopted to carry out the analysis. A multi-objective optimisation approach was applied to achieve optimal water availability and quality in the storage. The multi-objective optimisation model included three objective functions which were: water volume and two water quality parameters: salinity and turbidity. Results showed competing nature of water quantity and quality objectives and established the trade-offs. It further showed that it was possible to generate a range of optimal solutions to effectively manage those trade-offs. The trade-off analysis explored and informed that selective harvesting of inflows is effective to improve water quality in storage. However, with strict water quality restriction there is a considerable loss in water volume. The robustness of the optimisation approach used in this study was confirmed through sensitivity and uncertainty analysis. The research work also incorporated various spatio-temporal scenario analyses to systematically articulate long-term and short-term operational planning strategies. Operational decisions around possible harvesting regimes while achieving optimal water quantity and quality and meeting all water demands were established. The climate change analysis revealed that optimal management of water quantity and quality in storage became extremely challenging under future climate projections. The high reduction in storage volume in the future will lead to several challenges such as water supply shortfall and inability to undertake selective harvesting due to reduced water quality levels. In this context, selective harvesting of inflows based on water quality will no longer be an option to manage water quantity and quality optimally in storage. Some significant conclusions of this research work included the establishment of trade-offs between water quality and quantity objectives particular to this configuration of water supply system. The work demonstrated that selective harvesting of inflows will improve the stored water quality, and this finding along with the approach used is a significant contribution to decision makers working within the water sector. The simulation-optimisation approach is very effective in providing a range of optimal solutions, which can be used to make more informed decisions around achieving optimal water quality and quantity in storage. It was further demonstrated that there are range of planning periods, both long-term (>10 years) and short-term (<1 year), all of which offer distinct advantages and provides useful insights, making this an additional key contribution of the work. Importantly, climate change was also considered where it was found that diminishing water resources, particularly to this geographic location, makes it increasingly difficult to optimise both quality and quantity in storage providing further useful insights from this work.
- Description: Doctor of Philosophy
- Authors: Dey, Sayani
- Date: 2023
- Type: Text , Thesis , PhD
- Full Text:
- Description: As the world progresses, water resources are likely to be subjected to much greater pressures than in the past. Even though the principal water problem revolves around inadequate and uncertain water supplies, water quality management plays an equally important role. Availability of good quality water is paramount to sustainability of human population as well as the environment. Achieving water quality and quantity objectives can be conflicting and becomes more complicated with challenges like, climate change, growing populations and changed land uses. Managing adequate water quality in a reservoir gets complicated by multiple inflows with different water quality levels often resulting in poor water quality. Hence, it is fundamental to approach this issue in a more systematic, comprehensive, and coordinated fashion. Most previous studies related to water resources management focused on water quantity and considered water quality separately. However, this research study focused on considering water quantity and quality objectives simultaneously in a single model to explore and understand the relationship between them in a reservoir system. A case study area was identified in Western Victoria, Australia with water quantity and quality challenges. Taylors Lake of Grampians System in Victoria, Australia receives water from multiple sources of differing quality and quantity and has the abovesaid problems. A combined simulation and optimisation approach was adopted to carry out the analysis. A multi-objective optimisation approach was applied to achieve optimal water availability and quality in the storage. The multi-objective optimisation model included three objective functions which were: water volume and two water quality parameters: salinity and turbidity. Results showed competing nature of water quantity and quality objectives and established the trade-offs. It further showed that it was possible to generate a range of optimal solutions to effectively manage those trade-offs. The trade-off analysis explored and informed that selective harvesting of inflows is effective to improve water quality in storage. However, with strict water quality restriction there is a considerable loss in water volume. The robustness of the optimisation approach used in this study was confirmed through sensitivity and uncertainty analysis. The research work also incorporated various spatio-temporal scenario analyses to systematically articulate long-term and short-term operational planning strategies. Operational decisions around possible harvesting regimes while achieving optimal water quantity and quality and meeting all water demands were established. The climate change analysis revealed that optimal management of water quantity and quality in storage became extremely challenging under future climate projections. The high reduction in storage volume in the future will lead to several challenges such as water supply shortfall and inability to undertake selective harvesting due to reduced water quality levels. In this context, selective harvesting of inflows based on water quality will no longer be an option to manage water quantity and quality optimally in storage. Some significant conclusions of this research work included the establishment of trade-offs between water quality and quantity objectives particular to this configuration of water supply system. The work demonstrated that selective harvesting of inflows will improve the stored water quality, and this finding along with the approach used is a significant contribution to decision makers working within the water sector. The simulation-optimisation approach is very effective in providing a range of optimal solutions, which can be used to make more informed decisions around achieving optimal water quality and quantity in storage. It was further demonstrated that there are range of planning periods, both long-term (>10 years) and short-term (<1 year), all of which offer distinct advantages and provides useful insights, making this an additional key contribution of the work. Importantly, climate change was also considered where it was found that diminishing water resources, particularly to this geographic location, makes it increasingly difficult to optimise both quality and quantity in storage providing further useful insights from this work.
- 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
Efficient texture descriptors for image segmentation
- Authors: Tania, Sheikh
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text: false
- 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
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
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: false
- 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
Revision and validation of the Australian Competency Standards for Occupational Therapy Driver Assessors to ensure best practice
- Authors: Fields, Sally
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Occupational therapy driver assessment and rehabilitation is an advanced and complex area of practice. Users of this service require that occupational therapy driver assessors are, and remain, competent in their role. Competency standards support and inform occupational therapy driver assessment and rehabilitation practice, ensure standardisation of practice, and determine whether practice can be deemed competent. Competency standards for occupational therapy driver assessors in one Australian state, Victoria, were published in 1998 to provide a benchmark for service provision and guide training. Since then, occupational therapy driver assessor practice has undergone further developments and growth, including a significant increase in research evidence underpinning this advanced practice area. As a result, the competency standards required revision to reflect contemporary practice and enable their use and application across all Australian states and territories. The purpose of the research program reported in this thesis was to revise and validate the Australian Competency Standards for Occupational Therapy Driver Assessors and determine if education and practice using these standards led to increased adherence to their use in clinical practice. A sequential, exploratory, mixed methods design was used within a pragmatist research paradigm to revise and validate the competency standards for occupational therapy driver assessors from a national perspective. Four separate research studies were conducted. In the first study, an overview was undertaken to summarise the current evidence for including cognitive and perceptual assessments within fitness-to-drive evaluations, to inform the revision of the competency standards for occupational therapy driver assessors. The second study involved focus groups with Australian occupational therapy driver assessors and expert educators and identified the changes and revisions required to be made to the Victorian competency standards for occupational therapy driver assessors. Content themes and changes were extracted from the focus groups and combined with research evidence to draft the revised standards. The third study collected feedback from consumers and Australian driver licensing authorities to incorporate into the revised draft. This was followed by a two-round Delphi process with Australian occupational therapy driver assessors to achieve consensus and validate the Australian Competency Standards for Occupational Therapy Driver Assessors. A high level of consensus on the content of all competency standards and underlying practice behaviours was obtained in the final round. Finally, a mixed-methods multiple case-study methodology was adopted, and multiple forms of evidence were collected from file audits, semi-structured interviews and an individualised education session with occupational therapy driver assessors. This study demonstrated that, for this sample, occupational therapy driver assessors’ adherence to the Australian Competency Standards for Occupational Therapy Driver Assessors increased following an individually tailored education package about the standards. The research in this thesis has contributed to the evidence base for occupational therapy driver assessor practice. The Australian Competency Standards for Occupational Therapy Driver Assessors have been revised, validated and published, and the impact of an education package to increase adherence has been investigated. These competency standards: (i) assist occupational therapy driver assessors’ clinical practice, support occupational therapy registration and regulatory agencies to evaluate practice against a standard and (iii) provide universities with a framework to deliver postgraduate training in occupational therapy driver assessment and rehabilitation. Finally, this research has described a process that can be utilised in other areas of occupational therapy practice to develop and validate competency standards.
- Description: Doctor of Philosophy
- Authors: Fields, Sally
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Occupational therapy driver assessment and rehabilitation is an advanced and complex area of practice. Users of this service require that occupational therapy driver assessors are, and remain, competent in their role. Competency standards support and inform occupational therapy driver assessment and rehabilitation practice, ensure standardisation of practice, and determine whether practice can be deemed competent. Competency standards for occupational therapy driver assessors in one Australian state, Victoria, were published in 1998 to provide a benchmark for service provision and guide training. Since then, occupational therapy driver assessor practice has undergone further developments and growth, including a significant increase in research evidence underpinning this advanced practice area. As a result, the competency standards required revision to reflect contemporary practice and enable their use and application across all Australian states and territories. The purpose of the research program reported in this thesis was to revise and validate the Australian Competency Standards for Occupational Therapy Driver Assessors and determine if education and practice using these standards led to increased adherence to their use in clinical practice. A sequential, exploratory, mixed methods design was used within a pragmatist research paradigm to revise and validate the competency standards for occupational therapy driver assessors from a national perspective. Four separate research studies were conducted. In the first study, an overview was undertaken to summarise the current evidence for including cognitive and perceptual assessments within fitness-to-drive evaluations, to inform the revision of the competency standards for occupational therapy driver assessors. The second study involved focus groups with Australian occupational therapy driver assessors and expert educators and identified the changes and revisions required to be made to the Victorian competency standards for occupational therapy driver assessors. Content themes and changes were extracted from the focus groups and combined with research evidence to draft the revised standards. The third study collected feedback from consumers and Australian driver licensing authorities to incorporate into the revised draft. This was followed by a two-round Delphi process with Australian occupational therapy driver assessors to achieve consensus and validate the Australian Competency Standards for Occupational Therapy Driver Assessors. A high level of consensus on the content of all competency standards and underlying practice behaviours was obtained in the final round. Finally, a mixed-methods multiple case-study methodology was adopted, and multiple forms of evidence were collected from file audits, semi-structured interviews and an individualised education session with occupational therapy driver assessors. This study demonstrated that, for this sample, occupational therapy driver assessors’ adherence to the Australian Competency Standards for Occupational Therapy Driver Assessors increased following an individually tailored education package about the standards. The research in this thesis has contributed to the evidence base for occupational therapy driver assessor practice. The Australian Competency Standards for Occupational Therapy Driver Assessors have been revised, validated and published, and the impact of an education package to increase adherence has been investigated. These competency standards: (i) assist occupational therapy driver assessors’ clinical practice, support occupational therapy registration and regulatory agencies to evaluate practice against a standard and (iii) provide universities with a framework to deliver postgraduate training in occupational therapy driver assessment and rehabilitation. Finally, this research has described a process that can be utilised in other areas of occupational therapy practice to develop and validate competency standards.
- Description: Doctor of Philosophy
Single- and multiobjective reinforcement learning in dynamic adversarial games
- Authors: Kurniawan, Budi
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis uses reinforcement learning (RL) to address dynamic adversarial games in the context of air combat manoeuvring simulation. A sequential decision problem commonly encountered in the field of operations research, air combat manoeuvring simulation conventionally relied on agent programming methods that required significant domain knowledge to be manually encoded into the simulation environment. These methods are appropriate for determining the effectiveness of existing tactics in different simulated scenarios. However, in order to maximise the advantages provided by new technologies (such as autonomous aircraft), new tactics will need to be discovered. A proven technique for solving sequential decision problems, RL has the potential to discover these new tactics. This thesis explores four RL approaches—tabular, deep, discrete-to-deep and multiobjective— as mechanisms for discovering new behaviours in simulations of air combat manoeuvring. Itimplements and tests several methods for each approach and compares those methods in terms of the learning time, baseline and comparative performances, and implementation complexity. In addition to evaluating the utility of existing approaches to the specific task of air combat manoeuvring, this thesis proposes and investigates two novel methods, discrete-to-deep supervised policy learning (D2D-SPL) and discrete-to-deep supervised Q-value learning (D2D-SQL), which can be applied more generally. D2D-SPL and D2D-SQL offer the generalisability of deep RL at a cost closer to the tabular approach.
- Description: Doctor of Philosophy
- Authors: Kurniawan, Budi
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis uses reinforcement learning (RL) to address dynamic adversarial games in the context of air combat manoeuvring simulation. A sequential decision problem commonly encountered in the field of operations research, air combat manoeuvring simulation conventionally relied on agent programming methods that required significant domain knowledge to be manually encoded into the simulation environment. These methods are appropriate for determining the effectiveness of existing tactics in different simulated scenarios. However, in order to maximise the advantages provided by new technologies (such as autonomous aircraft), new tactics will need to be discovered. A proven technique for solving sequential decision problems, RL has the potential to discover these new tactics. This thesis explores four RL approaches—tabular, deep, discrete-to-deep and multiobjective— as mechanisms for discovering new behaviours in simulations of air combat manoeuvring. Itimplements and tests several methods for each approach and compares those methods in terms of the learning time, baseline and comparative performances, and implementation complexity. In addition to evaluating the utility of existing approaches to the specific task of air combat manoeuvring, this thesis proposes and investigates two novel methods, discrete-to-deep supervised policy learning (D2D-SPL) and discrete-to-deep supervised Q-value learning (D2D-SQL), which can be applied more generally. D2D-SPL and D2D-SQL offer the generalisability of deep RL at a cost closer to the tabular approach.
- Description: Doctor of Philosophy
Teaching with difference : barriers and enablers for teachers with impairments in their professional roles
- Authors: Skene, Gerrard
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Amidst the current groundswell of inclusive practices adopted in learning institutions, there would appear to be a paucity of research regarding the barriers and enablers experienced by teachers with impairments in Australian education systems (Burke, 2016; Pritchard, 2010; Sheridan & Kotevski, 2014). This thesis presents an examination of national and international literature where an imprecise range of issues for teachers with impairments is identified. The social model of disability has been adopted as the overarching theoretical perspective for this study. The conceptualisation of teaching with impairment, rather than about impairment, embodies the notion of teachers with impairments as being culturally relevant educators (Pritchard, 2010). Narrative inquiry, in conjunction with Clandinin and Connelly’s (2000) three-dimensional space approach as a thematical analysis methodology, has been employed and supports the investigation of ten teachers with impairments working in professional education roles within Australia. Narrative interviews were conducted with each of the ten participants with the aim of identifying barriers and enablers within the lived experiences of teachers with impairments. This study identified a silence in relation to teachers with impairments, and to address this silence has amplified the voices of teachers with impairments. Five primary themes emerged from the data to provide insights into barriers and enablers experienced by teachers with impairments. These themes are: Thinking about becoming a teacher; The limiting attitudes of others; Connecting with students and parents; Notions of teaching spaces; and I get by with a little help from my friends. This study found that teachers with impairments do experience adverse attitudes and biases in Australian teaching institutions despite there being laws that have been specifically designed to prevent disability discrimination. Bias, experienced as discrimination towards teachers with impairments, extends to career promotion and workplace advancement opportunities. Conversely, the study also found that respectful conversations about impairment which took place both inside and outside teaching places, highlighted how having open conversations about reasonable adjustments can lead to actions that become enablers for teachers with impairments. This study commences the important work of giving voice to teachers with impairments and creates a space to challenge dominant perspectives. The thesis concludes that more needs to be done to challenge the constructed normative attitudes that are responsible for setting teachers with impairments apart and resulting in them being mostly undetected within the teacher population; Doctor of Philosophy
- Authors: Skene, Gerrard
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Amidst the current groundswell of inclusive practices adopted in learning institutions, there would appear to be a paucity of research regarding the barriers and enablers experienced by teachers with impairments in Australian education systems (Burke, 2016; Pritchard, 2010; Sheridan & Kotevski, 2014). This thesis presents an examination of national and international literature where an imprecise range of issues for teachers with impairments is identified. The social model of disability has been adopted as the overarching theoretical perspective for this study. The conceptualisation of teaching with impairment, rather than about impairment, embodies the notion of teachers with impairments as being culturally relevant educators (Pritchard, 2010). Narrative inquiry, in conjunction with Clandinin and Connelly’s (2000) three-dimensional space approach as a thematical analysis methodology, has been employed and supports the investigation of ten teachers with impairments working in professional education roles within Australia. Narrative interviews were conducted with each of the ten participants with the aim of identifying barriers and enablers within the lived experiences of teachers with impairments. This study identified a silence in relation to teachers with impairments, and to address this silence has amplified the voices of teachers with impairments. Five primary themes emerged from the data to provide insights into barriers and enablers experienced by teachers with impairments. These themes are: Thinking about becoming a teacher; The limiting attitudes of others; Connecting with students and parents; Notions of teaching spaces; and I get by with a little help from my friends. This study found that teachers with impairments do experience adverse attitudes and biases in Australian teaching institutions despite there being laws that have been specifically designed to prevent disability discrimination. Bias, experienced as discrimination towards teachers with impairments, extends to career promotion and workplace advancement opportunities. Conversely, the study also found that respectful conversations about impairment which took place both inside and outside teaching places, highlighted how having open conversations about reasonable adjustments can lead to actions that become enablers for teachers with impairments. This study commences the important work of giving voice to teachers with impairments and creates a space to challenge dominant perspectives. The thesis concludes that more needs to be done to challenge the constructed normative attitudes that are responsible for setting teachers with impairments apart and resulting in them being mostly undetected within the teacher population; Doctor of Philosophy
The association of circular RNAs with hypertension
- Authors: Woods, Bradley
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis contains six chapters in total with chapter 1 being a literature overview and chapter 2 being a summary of material and methods. The three results chapters contain all my own work unless stated otherwise and lastly chapter 6 is discussion and conclusions linking together the work undertaken in this thesis.
- Description: Doctor of Philosophy
- Authors: Woods, Bradley
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis contains six chapters in total with chapter 1 being a literature overview and chapter 2 being a summary of material and methods. The three results chapters contain all my own work unless stated otherwise and lastly chapter 6 is discussion and conclusions linking together the work undertaken in this thesis.
- Description: Doctor of Philosophy
The effect of moxonidine on atherosclerosis
- Authors: Nguyen, Dinh Tam
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Background: Atherosclerosis is an inflammatory disease with hypertension as a risk factor. Moxonidine decreases blood pressure and has an anti-inflammatory effect. Aim: To investigate the effect of moxonidine on atherosclerosis: Key methods and results: For the in vivo experiment, twenty male apolipoprotein E-deficient mice were randomized into two groups: the control and moxonidine treatment groups. The mice from the moxonidine treatment group were treated with moxonidine via drinking water (69 mg/L) which equated to a dose of 18 mg/kg body weight per day, whereas the mice from the control group received normal drinking water without moxonidine. All the mice received angiotensin II (1
- Description: Doctor of Philosophy
- Authors: Nguyen, Dinh Tam
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Background: Atherosclerosis is an inflammatory disease with hypertension as a risk factor. Moxonidine decreases blood pressure and has an anti-inflammatory effect. Aim: To investigate the effect of moxonidine on atherosclerosis: Key methods and results: For the in vivo experiment, twenty male apolipoprotein E-deficient mice were randomized into two groups: the control and moxonidine treatment groups. The mice from the moxonidine treatment group were treated with moxonidine via drinking water (69 mg/L) which equated to a dose of 18 mg/kg body weight per day, whereas the mice from the control group received normal drinking water without moxonidine. All the mice received angiotensin II (1
- Description: Doctor of Philosophy
The idea of audience : audience development and the creative industries in Australia's small-to-medium performing arts sector
- Authors: Piening, Simon
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: In recent decades, the governance of arts and culture in Australia has been dominated by the “creative industries” model, which is a market-driven approach to cultural policy that seeks to bring together those workers who operate in the realm of creativity with those who have the knowledge and resources to monetise their creative output. The increased focus on market outcomes has resulted in the need for arts organisation to pay much greater attention to developing audiences and cultivating consumers for the arts. However, strikingly absent from much of the discussion concerning audience development in the arts has been the voices of the artists and arts workers themselves, whose work sits at the very heart of any relationship with the audience. The research study that is the subject of this thesis sought to better understand the audience relationship from the perspective of artists and arts workers operating in Melbourne’s small-to-medium performing arts sector, which is a not-for-profit niche of the performing arts industry that has been charged with creating new works and pushing creative boundaries. In light of the increasingly marketised environment for cultural production, the study asked two broad questions: How do these arts professionals conceptualise their relationship with the audience?; and What role do they envisage for the performing arts in their communities? Through individual interviews and a series of group discussions occurring over a 12-month period between 2017 and 2018, arts professionals from the small-to-medium performing arts sector in Melbourne, Australia, discussed the ways in which the rise of the market-oriented creative industries had been impacting on their understanding of, and relationship with, the audience. The study found that the growing demands of the market and the commodification of artistic work had, for many arts professionals, increased the sense of distance between the artist and the audience and had resulted in confusion over the role and value of art in contemporary society. Despite this, arts workers, through their craft, were seeking greater engagement with their communities and were contributing to a more diverse and robust public sphere. As the authors and architects of the aesthetic experience, artists, arts workers and arts organisations have a profound impact in shaping the audience’s understanding of, and relationship with, the arts (Belfiore & Bennett, 2008). Yet much audience development research and practice has focused on understanding the attitudes and motivations of audience members in relation to the arts and ignored or minimised the important contribution that artists themselves might be making to developing audiences. This study’s aim was to address a significant gap in the understanding of the needs and motivations of arts professionals with regard to their relationship with the audience, and, in so doing, argued for a re-imagining of the field and practice of audience development that considers the needs of both the producers and consumers of culture.
- Description: Doctor of Philosophy
- Authors: Piening, Simon
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: In recent decades, the governance of arts and culture in Australia has been dominated by the “creative industries” model, which is a market-driven approach to cultural policy that seeks to bring together those workers who operate in the realm of creativity with those who have the knowledge and resources to monetise their creative output. The increased focus on market outcomes has resulted in the need for arts organisation to pay much greater attention to developing audiences and cultivating consumers for the arts. However, strikingly absent from much of the discussion concerning audience development in the arts has been the voices of the artists and arts workers themselves, whose work sits at the very heart of any relationship with the audience. The research study that is the subject of this thesis sought to better understand the audience relationship from the perspective of artists and arts workers operating in Melbourne’s small-to-medium performing arts sector, which is a not-for-profit niche of the performing arts industry that has been charged with creating new works and pushing creative boundaries. In light of the increasingly marketised environment for cultural production, the study asked two broad questions: How do these arts professionals conceptualise their relationship with the audience?; and What role do they envisage for the performing arts in their communities? Through individual interviews and a series of group discussions occurring over a 12-month period between 2017 and 2018, arts professionals from the small-to-medium performing arts sector in Melbourne, Australia, discussed the ways in which the rise of the market-oriented creative industries had been impacting on their understanding of, and relationship with, the audience. The study found that the growing demands of the market and the commodification of artistic work had, for many arts professionals, increased the sense of distance between the artist and the audience and had resulted in confusion over the role and value of art in contemporary society. Despite this, arts workers, through their craft, were seeking greater engagement with their communities and were contributing to a more diverse and robust public sphere. As the authors and architects of the aesthetic experience, artists, arts workers and arts organisations have a profound impact in shaping the audience’s understanding of, and relationship with, the arts (Belfiore & Bennett, 2008). Yet much audience development research and practice has focused on understanding the attitudes and motivations of audience members in relation to the arts and ignored or minimised the important contribution that artists themselves might be making to developing audiences. This study’s aim was to address a significant gap in the understanding of the needs and motivations of arts professionals with regard to their relationship with the audience, and, in so doing, argued for a re-imagining of the field and practice of audience development that considers the needs of both the producers and consumers of culture.
- Description: Doctor of Philosophy
The role of immune cells in ovarian cancer
- Authors: Ahmady, Farah
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Ovarian cancer remains the leading cause of gynaecological disease related death in women worldwide. Patients given standard treatment have low survival rates and immunotherapy remains unsuccessful. This is largely due to the suppressive tumour microenvironment (TME) and the interaction of the different cells being poorly understood. This has sparked interest in understanding the functions of immune cells and their contribution to the TME. In chapter 3, B and T cells were characterised in samples collected from chemo-naïve highgrade serous ovarian cancer (HGSOC) patients and compared to benign and healthy controls. B cells were able to express the T cell exhaustion marker T cell immunoglobulin and mucin domain-3 (TIM-3) on their surface. Blood derived B cells of benign patients expressed less TIM-3 compared to high-grade and healthy donors. Alterations in TIM-3 expression on B cells suggests that the TME may not be causing B cells to harbour an exhaustion phenotype. The frequency of circulating mucosal-associated invariant T cells (MAIT cells) was reduced in benign and high-grade patients compared to healthy donors. Blood derived MAIT cells of healthy donors stimulated with 5-OP-RU antigen and cultured with ovarian cancer cell line supernatants had a reduced capacity of producing tumour necrosis factor (TNF)-a compared to control. The reduced frequency of MAIT cells at the premalignant state of the disease indicates that malignancy of the disease is not necessarily the contributing factor in the reduction observed. As TNF-a is a key anti-tumour cytokine expressed by MAIT cells, the impaired production may indicate defects in their function. Low dose-dense (LDD) chemotherapy has recently shown promise as depicted in a clinical study by Kannourakis et al. where LDD treated HGSOC patients had longer survival than those treated with maximum tolerated dose (MTD). It is postulated that this may be due to aspects of the immune system, however the effects of LDD chemotherapy on immune cells remains unknown. In chpter 4, circulating B and T cells of LDD treated patients were characterised and compared to untreated controls. The key finding of this study was the immunostimulatory attributes of LDD regimen in a range of B and T cell populations via their increased expression of TNF-a compared to untreated controls and healthy donors. The frequency of MAIT cells, however, was reduced in LDD treated patients, suggesting that these cells may not contribute to the immunostimulatory aspects, and that this regimen may impact their frequency by creating an environment which may not be compatible for MAIT cell survival. In chapter 5, expression of immuno-oncology protein markers in benign and high-grade primary and metastasised tumours were determined for alterations in hot and cold tumour regions using Digital Spatial Profiling (DSP). An increased expression of immune cell, costimulatory and inhibitory markers were apparent in high-grade tumours compared to benign. The stimulator of interferon genes (STING) marker was studied further, and its expression was also higher in high-grade tumours compared to benign, with cisplatin further enhancing its expression in ovarian cancer cell lines. There were alterations in the expression of some downstream molecules, however interferon (IFN)-b, the key cytokine produced in the activated STING pathway, was virtually non-existent. This suggests a defect in the pathway which if restored, may contribute to some of the known anti-tumour functions of the pathway. The results from these studies provide an understanding of differences in the immune profile of non-malignant and malignant ovarian cancer. These findings work together to improve our understanding of the unique TME with the aim to identify potential immune therapeutic targets for future study.
- Description: Doctor of Philosophy
- Authors: Ahmady, Farah
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Ovarian cancer remains the leading cause of gynaecological disease related death in women worldwide. Patients given standard treatment have low survival rates and immunotherapy remains unsuccessful. This is largely due to the suppressive tumour microenvironment (TME) and the interaction of the different cells being poorly understood. This has sparked interest in understanding the functions of immune cells and their contribution to the TME. In chapter 3, B and T cells were characterised in samples collected from chemo-naïve highgrade serous ovarian cancer (HGSOC) patients and compared to benign and healthy controls. B cells were able to express the T cell exhaustion marker T cell immunoglobulin and mucin domain-3 (TIM-3) on their surface. Blood derived B cells of benign patients expressed less TIM-3 compared to high-grade and healthy donors. Alterations in TIM-3 expression on B cells suggests that the TME may not be causing B cells to harbour an exhaustion phenotype. The frequency of circulating mucosal-associated invariant T cells (MAIT cells) was reduced in benign and high-grade patients compared to healthy donors. Blood derived MAIT cells of healthy donors stimulated with 5-OP-RU antigen and cultured with ovarian cancer cell line supernatants had a reduced capacity of producing tumour necrosis factor (TNF)-a compared to control. The reduced frequency of MAIT cells at the premalignant state of the disease indicates that malignancy of the disease is not necessarily the contributing factor in the reduction observed. As TNF-a is a key anti-tumour cytokine expressed by MAIT cells, the impaired production may indicate defects in their function. Low dose-dense (LDD) chemotherapy has recently shown promise as depicted in a clinical study by Kannourakis et al. where LDD treated HGSOC patients had longer survival than those treated with maximum tolerated dose (MTD). It is postulated that this may be due to aspects of the immune system, however the effects of LDD chemotherapy on immune cells remains unknown. In chpter 4, circulating B and T cells of LDD treated patients were characterised and compared to untreated controls. The key finding of this study was the immunostimulatory attributes of LDD regimen in a range of B and T cell populations via their increased expression of TNF-a compared to untreated controls and healthy donors. The frequency of MAIT cells, however, was reduced in LDD treated patients, suggesting that these cells may not contribute to the immunostimulatory aspects, and that this regimen may impact their frequency by creating an environment which may not be compatible for MAIT cell survival. In chapter 5, expression of immuno-oncology protein markers in benign and high-grade primary and metastasised tumours were determined for alterations in hot and cold tumour regions using Digital Spatial Profiling (DSP). An increased expression of immune cell, costimulatory and inhibitory markers were apparent in high-grade tumours compared to benign. The stimulator of interferon genes (STING) marker was studied further, and its expression was also higher in high-grade tumours compared to benign, with cisplatin further enhancing its expression in ovarian cancer cell lines. There were alterations in the expression of some downstream molecules, however interferon (IFN)-b, the key cytokine produced in the activated STING pathway, was virtually non-existent. This suggests a defect in the pathway which if restored, may contribute to some of the known anti-tumour functions of the pathway. The results from these studies provide an understanding of differences in the immune profile of non-malignant and malignant ovarian cancer. These findings work together to improve our understanding of the unique TME with the aim to identify potential immune therapeutic targets for future study.
- Description: Doctor of Philosophy
The role of sprint training in hamstring strain injury prevention for field sport athletes
- Authors: Freeman, Brock
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Hamstring strain injuries (HSI) are regularly reported as the most common injury in many field-based sports with a high-speed running (HSR) component. Typically, these injuries occur during sprinting efforts, predominantly in the Biceps Femoris Long Head (BFLH). Furthermore, the burden of HSI is amongst the highest in field sports, and the risk of recurrent injury is elevated, and inflated by age. It is of interest to managers, technical coaches, physical preparation staff and athletes to reduce the risk of sustaining a HSI. Therefore, extensive research in HSI has identified several non-modifiable and modifiable risk factors, such as eccentric hamstring strength, BFLH fascicle length, and HSR exposure. Currently, almost all interventions designed to reduce the risk of HSI have utilised resistance training or stretching interventions. This is despite the scientific literature indicating that; 1) sprinting is the most common mechanism associated with hamstring strain injury, and 2) sprinting places a far greater demand on the hamstrings than interventions that are resistance or flexibility based. Therefore, the primary aim of this thesis was to establish the role of sprint training in HSI prevention in field sport athletes. The aim of Study 1 was to understand the beliefs and practices of professional Australian Football (AF) physical performance coaches towards the training and assessment prescribed to mitigate the risk of HSI. A Delphi-validated mixed methods survey was implemented to assess the beliefs and practices of High-Performance Managers of professional AF teams. All the participants in this study reported that they believed sprinting (acceleration and maximum speed) was the most common activity associated with HSI. Similarly, all participants also indicated they performed sprint training for injury prevention purposes. However, a range of relative speeds were reported to quantify HSR, whilst a sprint was reported as 85%Vmax. Whilst respondents reported they believed that sprint training was important, one participant indicated that they felt the need to be conservative with the prescription of sprint training for fear of injury, and the consequences associated with this. Due to the identified discrepancies in speed thresholds used in practical setting (Study 1) and academic settings (Literature Review), Study 2 was designed to determine the absolute, and relative speeds associated with jogging, running, striding, near maximum sprinting, and sprinting. The secondary aim was to visually describe the gait patterns associated with HSR and sprinting. Fifteen participants completed two data collection periods, where they performed a series of run throughs at different gait patterns. These gait patterns were adapted from a review of time-motion research in field sports. The running gaits of jogging, running, striding, near-maximum sprinting, and sprinting correspond with the relative speeds of 56%Vmax, 66%Vmax, 78%Vmax, 87%Vmax, and 100%Vmax, respectively. Significant (p = 0.01) differences were observed for all variables between striding, near-maximum sprinting, and sprinting. This highlights that previously reported thresholds in Study 1 are likely not quantifying the true sprinting demands. Publicly available injury information indicates a spike in HSI during the 2018 Australian Football League (AFL) season, a trend that occurred in the relatively uninterrupted 2020 AFL season. As Study 2 indicated that thresholds used to quantify the demands of sprinting in training and competition, Study 3 primarily aimed to determine the amount of running completed in relative speed bands during the pre-season and then the first eight weeks of the season. The secondary aim was to determine how individual athletes vary from the group average across the pre-season and the first eight rounds of the season. This study completed a retrospective analysis of 55 professional Australian footballers during the pre-season and first eight rounds of the 2019 season. Significantly less (p < 0.05) weekly volume was reported during the first 8 weeks of the season in the speed thresholds of 71-80%Vmax, 81-90%Vmax, and 91-100%Vmax. However, athletes in this study only completed an average of 18m above 90%Vmax in the pre-season, a stimulus too low to achieve an injury prevention and conditioning effect. Individual analysis highlighted that whilst a small number of athletes achieved a consistent sprinting load, several athletes did not achieve more than 2m above 90%Vmax during both the pre and in-season periods. This lack of preparation may provide a rationale for the injury rates during the first eight rounds. To improve the preparation of athletes using a sprinting stimulus, Study 4 focussed on addressing modifiable risk factors for HSI. The primary aim of this study examined the effects of acceleration and maximum speed sprint training of eccentric hamstring strength, BFLH fascicle length, and sprint performance. Initially, a training study with 60 participants was planned, but due to the Victorian Government’s COVID-19 restrictions, this was modified to a case study design with 11 participants. A 6-week training intervention consisting of acceleration sprinting (<15m) or maximum speed sprinting with a gradual build up (flying 10-20m) was implemented. Participants that performed acceleration or maximum speed sprinting improved Biceps Femoris fascicle length by 23% and 20%, respectively. This was an increase of more than the Minimum Detectable Change (MDC95 = 0.96cm, 95% CI =0.93 – 0.99cm). The participants who completed normal training experienced no change in the BFLH fascicle length. Neither sprint training intervention produced a change in eccentric hamstring strength that was greater than the typical error in the test. Both sprinting interventions improved sprint performance outcomes, however both acceleration and maximum speed training produced a larger improvement in maximum speed (-11% and -9%, respectively) than in acceleration qualities (-2% and -3%, respectively). Both acceleration and maximum speed training incurred positive improvement in relative force production (F(0) (N/kg)) and relative power production (Pmax (W/kg)). This was similar for DRF and RFpeak and indicates that sprint training without resistance will improve Force-Velocity-Power Variables. This project has provided new information regarding the role of sprint training for hamstring strain injury prevention. Firstly, both 6 weeks of low volume acceleration and maximum speed sprinting improve BFLH fascicle length. Secondly, currently employed velocity thresholds in professional AF are likely too slow to quantify the HSR and sprinting demands. Thirdly, analysis using thresholds that are faster than previously reported revealed that the overall volume of sprinting (>90%Vmax) is too low to elicit an injury prevention or training stimulus. This information will inform the future practices of key stakeholders surrounding sprint training in field sport athletes. The identification of the positive benefits of maximum speed sprinting, and a faster, more accurate definition of sprinting has large potential to improve hamstring strain injury prevention and increase physical performance.
- Description: Doctor of Philosophy
- Authors: Freeman, Brock
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Hamstring strain injuries (HSI) are regularly reported as the most common injury in many field-based sports with a high-speed running (HSR) component. Typically, these injuries occur during sprinting efforts, predominantly in the Biceps Femoris Long Head (BFLH). Furthermore, the burden of HSI is amongst the highest in field sports, and the risk of recurrent injury is elevated, and inflated by age. It is of interest to managers, technical coaches, physical preparation staff and athletes to reduce the risk of sustaining a HSI. Therefore, extensive research in HSI has identified several non-modifiable and modifiable risk factors, such as eccentric hamstring strength, BFLH fascicle length, and HSR exposure. Currently, almost all interventions designed to reduce the risk of HSI have utilised resistance training or stretching interventions. This is despite the scientific literature indicating that; 1) sprinting is the most common mechanism associated with hamstring strain injury, and 2) sprinting places a far greater demand on the hamstrings than interventions that are resistance or flexibility based. Therefore, the primary aim of this thesis was to establish the role of sprint training in HSI prevention in field sport athletes. The aim of Study 1 was to understand the beliefs and practices of professional Australian Football (AF) physical performance coaches towards the training and assessment prescribed to mitigate the risk of HSI. A Delphi-validated mixed methods survey was implemented to assess the beliefs and practices of High-Performance Managers of professional AF teams. All the participants in this study reported that they believed sprinting (acceleration and maximum speed) was the most common activity associated with HSI. Similarly, all participants also indicated they performed sprint training for injury prevention purposes. However, a range of relative speeds were reported to quantify HSR, whilst a sprint was reported as 85%Vmax. Whilst respondents reported they believed that sprint training was important, one participant indicated that they felt the need to be conservative with the prescription of sprint training for fear of injury, and the consequences associated with this. Due to the identified discrepancies in speed thresholds used in practical setting (Study 1) and academic settings (Literature Review), Study 2 was designed to determine the absolute, and relative speeds associated with jogging, running, striding, near maximum sprinting, and sprinting. The secondary aim was to visually describe the gait patterns associated with HSR and sprinting. Fifteen participants completed two data collection periods, where they performed a series of run throughs at different gait patterns. These gait patterns were adapted from a review of time-motion research in field sports. The running gaits of jogging, running, striding, near-maximum sprinting, and sprinting correspond with the relative speeds of 56%Vmax, 66%Vmax, 78%Vmax, 87%Vmax, and 100%Vmax, respectively. Significant (p = 0.01) differences were observed for all variables between striding, near-maximum sprinting, and sprinting. This highlights that previously reported thresholds in Study 1 are likely not quantifying the true sprinting demands. Publicly available injury information indicates a spike in HSI during the 2018 Australian Football League (AFL) season, a trend that occurred in the relatively uninterrupted 2020 AFL season. As Study 2 indicated that thresholds used to quantify the demands of sprinting in training and competition, Study 3 primarily aimed to determine the amount of running completed in relative speed bands during the pre-season and then the first eight weeks of the season. The secondary aim was to determine how individual athletes vary from the group average across the pre-season and the first eight rounds of the season. This study completed a retrospective analysis of 55 professional Australian footballers during the pre-season and first eight rounds of the 2019 season. Significantly less (p < 0.05) weekly volume was reported during the first 8 weeks of the season in the speed thresholds of 71-80%Vmax, 81-90%Vmax, and 91-100%Vmax. However, athletes in this study only completed an average of 18m above 90%Vmax in the pre-season, a stimulus too low to achieve an injury prevention and conditioning effect. Individual analysis highlighted that whilst a small number of athletes achieved a consistent sprinting load, several athletes did not achieve more than 2m above 90%Vmax during both the pre and in-season periods. This lack of preparation may provide a rationale for the injury rates during the first eight rounds. To improve the preparation of athletes using a sprinting stimulus, Study 4 focussed on addressing modifiable risk factors for HSI. The primary aim of this study examined the effects of acceleration and maximum speed sprint training of eccentric hamstring strength, BFLH fascicle length, and sprint performance. Initially, a training study with 60 participants was planned, but due to the Victorian Government’s COVID-19 restrictions, this was modified to a case study design with 11 participants. A 6-week training intervention consisting of acceleration sprinting (<15m) or maximum speed sprinting with a gradual build up (flying 10-20m) was implemented. Participants that performed acceleration or maximum speed sprinting improved Biceps Femoris fascicle length by 23% and 20%, respectively. This was an increase of more than the Minimum Detectable Change (MDC95 = 0.96cm, 95% CI =0.93 – 0.99cm). The participants who completed normal training experienced no change in the BFLH fascicle length. Neither sprint training intervention produced a change in eccentric hamstring strength that was greater than the typical error in the test. Both sprinting interventions improved sprint performance outcomes, however both acceleration and maximum speed training produced a larger improvement in maximum speed (-11% and -9%, respectively) than in acceleration qualities (-2% and -3%, respectively). Both acceleration and maximum speed training incurred positive improvement in relative force production (F(0) (N/kg)) and relative power production (Pmax (W/kg)). This was similar for DRF and RFpeak and indicates that sprint training without resistance will improve Force-Velocity-Power Variables. This project has provided new information regarding the role of sprint training for hamstring strain injury prevention. Firstly, both 6 weeks of low volume acceleration and maximum speed sprinting improve BFLH fascicle length. Secondly, currently employed velocity thresholds in professional AF are likely too slow to quantify the HSR and sprinting demands. Thirdly, analysis using thresholds that are faster than previously reported revealed that the overall volume of sprinting (>90%Vmax) is too low to elicit an injury prevention or training stimulus. This information will inform the future practices of key stakeholders surrounding sprint training in field sport athletes. The identification of the positive benefits of maximum speed sprinting, and a faster, more accurate definition of sprinting has large potential to improve hamstring strain injury prevention and increase physical performance.
- Description: Doctor of Philosophy
Undergraduate nursing students’ team communication skills within a simulated emergency setting : a grounded theory study
- Authors: Bourke, Sharon
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Recognising and managing clinical deterioration is considered a high priority in health care with ineffective communication being a significant contributing factor to poor clinical outcomes for patients. Nurses are in a unique position to make a difference in influencing improvements in team communication. In Australia, nurse education has become more complicated and demanding with nursing students focus on behaviour skills, such as communication, becoming more difficult in a saturated curriculum. Simulation-based education has provided an experiential way to learn these complex skills. Although there has been much work in the healthcare literature on clinical teamwork, including communication and its intersection with patient safety, there is still a gap in explaining how individuals within the team contribute to communication. The purpose of this study was to explore and explain how nursing students communicate in simulated emergency settings and how factors, such as culture, language, gender, age and power, affect nursing students’ team communication. This study investigated how transitioning nursing students are prepared with the necessary skills to achieve effective team communication at the point of transition to clinical practice as registered nurses. In order to address the aims of the study, a constructivist grounded theory methodology, informed by Kathy Charmaz (2006), was employed. Using purposive sampling, third year nursing students were recruited from one Australian university, to undertake a structured team simulation experience. Participants worked in teams of three or four to experience the team communication whilst working together to care for a deteriorating patient in the form of a mannequin. Simulations were video recorded after which individual, in-depth, semi-structured interviews were conducted with 21 participants. In line with a grounded theory approach, data collection and analysis were conducted concurrently until theoretical saturation was achieved. In response to the central problem of how nursing students communicate in simulated emergency settings, a core process was established that explained the factors that affect team communication. This problem is conceptualised as Navigating uncertainty: Explaining communication of nursing students within an emergency setting. This theoretical construct helps to explain nursing students’ actions and insights into factors that influence their communication within emergency teams. The core process is represented in three transitional stages of the theory comprising: Finding a place in the team, Understanding and working out differences and Looking to the future: Developing strategies to improve communication. This process was mediated by contextual conditions of the student, the simulation and the team. The phases are reinforced by the three main categories of Having a place in the team, Knowing yourself, and Transitioning from student to registered nurse. These categories represent the key activities that nursing students were engaged with that led to the development of the core category and process. The generated findings and theory offer valuable insights into factors that influence team communication skills within emergency settings. The theory raises awareness of social processes undertaken by nursing students during team communication, and highlights obstacles that can assist educators and academics to structure team communication education to better meet the needs of nursing students transitioning to practice settings.
- Description: Doctor of Philosophy
- Authors: Bourke, Sharon
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Recognising and managing clinical deterioration is considered a high priority in health care with ineffective communication being a significant contributing factor to poor clinical outcomes for patients. Nurses are in a unique position to make a difference in influencing improvements in team communication. In Australia, nurse education has become more complicated and demanding with nursing students focus on behaviour skills, such as communication, becoming more difficult in a saturated curriculum. Simulation-based education has provided an experiential way to learn these complex skills. Although there has been much work in the healthcare literature on clinical teamwork, including communication and its intersection with patient safety, there is still a gap in explaining how individuals within the team contribute to communication. The purpose of this study was to explore and explain how nursing students communicate in simulated emergency settings and how factors, such as culture, language, gender, age and power, affect nursing students’ team communication. This study investigated how transitioning nursing students are prepared with the necessary skills to achieve effective team communication at the point of transition to clinical practice as registered nurses. In order to address the aims of the study, a constructivist grounded theory methodology, informed by Kathy Charmaz (2006), was employed. Using purposive sampling, third year nursing students were recruited from one Australian university, to undertake a structured team simulation experience. Participants worked in teams of three or four to experience the team communication whilst working together to care for a deteriorating patient in the form of a mannequin. Simulations were video recorded after which individual, in-depth, semi-structured interviews were conducted with 21 participants. In line with a grounded theory approach, data collection and analysis were conducted concurrently until theoretical saturation was achieved. In response to the central problem of how nursing students communicate in simulated emergency settings, a core process was established that explained the factors that affect team communication. This problem is conceptualised as Navigating uncertainty: Explaining communication of nursing students within an emergency setting. This theoretical construct helps to explain nursing students’ actions and insights into factors that influence their communication within emergency teams. The core process is represented in three transitional stages of the theory comprising: Finding a place in the team, Understanding and working out differences and Looking to the future: Developing strategies to improve communication. This process was mediated by contextual conditions of the student, the simulation and the team. The phases are reinforced by the three main categories of Having a place in the team, Knowing yourself, and Transitioning from student to registered nurse. These categories represent the key activities that nursing students were engaged with that led to the development of the core category and process. The generated findings and theory offer valuable insights into factors that influence team communication skills within emergency settings. The theory raises awareness of social processes undertaken by nursing students during team communication, and highlights obstacles that can assist educators and academics to structure team communication education to better meet the needs of nursing students transitioning to practice settings.
- Description: Doctor of Philosophy
Women’s lived experiences of their partners’ referral to a men’s behaviour change program : a feminist interpretative phenomenological analysis
- Authors: Zeuschner, Lauren
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Family violence (FV) is a significant social issue across Australia, where one woman is murdered by her current or former partner every week (State Government of Victoria, 2020). In an effort to increase the safety of women and children living in the state of Victoria, perpetrators of FV are routinely referred to a group intervention known as a Men’s Behaviour Change Program (MBCP). This research study sought to lay a foundation for understanding how women experience their partners’ referral to an MBCP, while exploring the meaning they ascribe to such an experience. At a fundamental level, the study aimed to elevate the voices of women and to contextualise their experiences. It was anticipated that this study would illuminate the profound insights of women regarding their experiences of such referrals, which have not been previously considered or acknowledged as being important. Nine women living in the regional city of Ballarat, Victoria, took part in this community-based research project, which was designed in collaboration with industry partners. Each woman engaged in a qualitative interview that was underpinned by the emergent methodology of feminist interpretative phenomenological analysis. Consequently, these interviews focused on the women’s thoughts, feelings and interpretations of the referral experience. Through analysis and discussion of the women’s narratives, referral to an MBCP was shown to have involved experiences of significant meaning, depth and consequence for victim survivors – clearly demonstrating an effect beyond perpetrator engagement with an MBCP. The findings from this study have revealed the way in which MBCP referrals fashion a new environment for victim survivors. It is an environment characterised by heightened hopes of change, experiences of being blamed and judged by external parties and includes a rising sense of indignation. This form of referral has also been exposed to be a period of pivotal assessment for victim survivors, and at a fundamental level, as an event in and of itself. The new understandings achieved through this study provide a foundation on which FV services, researchers and policymakers can now build. This study has also reinforced the notion that in order to be effective, FV services must be informed by the knowledge and experiences of the people who are most affected by those services.
- Description: Doctor of Philosophy
- Authors: Zeuschner, Lauren
- Date: 2022
- Type: Text , Thesis , PhD
- Full Text:
- Description: Family violence (FV) is a significant social issue across Australia, where one woman is murdered by her current or former partner every week (State Government of Victoria, 2020). In an effort to increase the safety of women and children living in the state of Victoria, perpetrators of FV are routinely referred to a group intervention known as a Men’s Behaviour Change Program (MBCP). This research study sought to lay a foundation for understanding how women experience their partners’ referral to an MBCP, while exploring the meaning they ascribe to such an experience. At a fundamental level, the study aimed to elevate the voices of women and to contextualise their experiences. It was anticipated that this study would illuminate the profound insights of women regarding their experiences of such referrals, which have not been previously considered or acknowledged as being important. Nine women living in the regional city of Ballarat, Victoria, took part in this community-based research project, which was designed in collaboration with industry partners. Each woman engaged in a qualitative interview that was underpinned by the emergent methodology of feminist interpretative phenomenological analysis. Consequently, these interviews focused on the women’s thoughts, feelings and interpretations of the referral experience. Through analysis and discussion of the women’s narratives, referral to an MBCP was shown to have involved experiences of significant meaning, depth and consequence for victim survivors – clearly demonstrating an effect beyond perpetrator engagement with an MBCP. The findings from this study have revealed the way in which MBCP referrals fashion a new environment for victim survivors. It is an environment characterised by heightened hopes of change, experiences of being blamed and judged by external parties and includes a rising sense of indignation. This form of referral has also been exposed to be a period of pivotal assessment for victim survivors, and at a fundamental level, as an event in and of itself. The new understandings achieved through this study provide a foundation on which FV services, researchers and policymakers can now build. This study has also reinforced the notion that in order to be effective, FV services must be informed by the knowledge and experiences of the people who are most affected by those services.
- Description: Doctor of Philosophy
A comparative analysis of the motivational factors of Chinese and non-Chinese tourists visiting Melbourne
- Authors: Soldatenko, Daria
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: This study is devoted to a comparison of motivational factors of travellers from China and non-Chinese countries visiting the same destination (Melbourne). Given the importance of the Chinese market to Australia, it seems important to explore this market in terms of motivational factors and understand its specifics and peculiarities. In addition, the topicality of such research was revealed through a content analysis of cross-cultural push/pull motivational studies in tourism relating to nationalities. Leiper’s model of tourist’s pre-trip psychological process (2004) was adapted and modified in terms of push and pull factors that combine not only needs and destination attributes, but also include a number of additional factors, such as information about recreation possibilities of visiting places, expectation about potential experiences during the trip, as well as means, namely money, time and absence of other constraints. The model enables an understanding of the linkages and relationships between the various motivational variables and their influence on destination choice. This study employs quantitative methods to examine and compare the motivational factors of two studied samples. Data were collected through an online survey, which was provided in two languages (English and Chinese). The data analysis was undertaken in Statistical Package for the Social Sciences (SPSS) - 26.0 software by the means of various descriptive and inferential statistical techniques, such as Principal Component Analysis (PCA), Independent T-tests, Multiple regression analysis, and Canonical correlation analysis. In addition, the relationships between motivational variables in a proposed model were examined by using Partial Least Squares Structural Equation Modelling (PLS-SEM). The present study revealed a number of differences in trip characteristics and tourist motivational factors between the Chinese and non-Chinese samples. The differences identified between the two target markets are closely related to traits of individualist and collectivist cultures. This conclusion verifies the findings of previous tourism research that culture influences travel behaviour. The knowledge of cultural differences in motivation is very important for enhancing the efficiency and effectiveness of international tourism marketing. In addition, customising the services, products, and marketing programs for specific markets results in a high level of tourist satisfaction, and that in turn, leads to an increase in financial benefits associated with customer satisfaction and loyalty. This research has both theoretical and practical scientific significance. One significant contribution of this research is the development of a model of interrelated motivational factors in the travel decision-making process that enables the identification of the most influential motivational factors in travel decisions. The relationships between the push and pull factors, such as motivations, destination attributes, information sources, expectations and constraints, and their influence on destination choice, were examined. In the present study, a close positive relationship between personal motivations and destination attributes, as well as a significant influence of information sources on expectations and destination choice were found. Such results highlight the importance of properly developed advertising and promotion strategies with special attention to their contents, emphasising particular push and pull factors for particular tourist markets or segments. In addition, the current study identified possible product bundles of tourists’ motivations and destination attributes and segmentation of visitors to Melbourne that might present valuable information for destination practitioners and marketers, as successful matching of push and pull factors is a prerequisite for effective and successful actions on attraction and retention of visitors. Identified similarities and differences between Chinese and non-Chinese samples in terms of their demographic profiles, trip characteristics, motivations for travelling, preferences of destination attributes, information source usage, trip expectations, constraints for travelling, and their evaluation of destination choice criteria provided useful information for developing specifically customised tourist products and services, as well as promotion programs, that are tailored to each market. Moreover, from theoretical perspective, the present study adds new depth to understanding the nature of motivational factors, affecting the travel decision-making process, and causal relationships among them. Thus, the study contributes to advancing both tourist behaviour research as well as tourism decision-making literature. In addition, this research identifies and addresses the gap in empirical research investigating tourists' behaviour patterns across economically and culturally different countries. As comparative motivational research of tourists from China and non-Chinese countries travelling to Australia had yet to be undertaken, this study might be considered important because it provides valuable information for targeting the main source countries for Australia. Such research may be especially valuable in post-COVID times when international borders open up and carefully planned marketing will be needed.
- Description: Doctor of Philosophy
- Authors: Soldatenko, Daria
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: This study is devoted to a comparison of motivational factors of travellers from China and non-Chinese countries visiting the same destination (Melbourne). Given the importance of the Chinese market to Australia, it seems important to explore this market in terms of motivational factors and understand its specifics and peculiarities. In addition, the topicality of such research was revealed through a content analysis of cross-cultural push/pull motivational studies in tourism relating to nationalities. Leiper’s model of tourist’s pre-trip psychological process (2004) was adapted and modified in terms of push and pull factors that combine not only needs and destination attributes, but also include a number of additional factors, such as information about recreation possibilities of visiting places, expectation about potential experiences during the trip, as well as means, namely money, time and absence of other constraints. The model enables an understanding of the linkages and relationships between the various motivational variables and their influence on destination choice. This study employs quantitative methods to examine and compare the motivational factors of two studied samples. Data were collected through an online survey, which was provided in two languages (English and Chinese). The data analysis was undertaken in Statistical Package for the Social Sciences (SPSS) - 26.0 software by the means of various descriptive and inferential statistical techniques, such as Principal Component Analysis (PCA), Independent T-tests, Multiple regression analysis, and Canonical correlation analysis. In addition, the relationships between motivational variables in a proposed model were examined by using Partial Least Squares Structural Equation Modelling (PLS-SEM). The present study revealed a number of differences in trip characteristics and tourist motivational factors between the Chinese and non-Chinese samples. The differences identified between the two target markets are closely related to traits of individualist and collectivist cultures. This conclusion verifies the findings of previous tourism research that culture influences travel behaviour. The knowledge of cultural differences in motivation is very important for enhancing the efficiency and effectiveness of international tourism marketing. In addition, customising the services, products, and marketing programs for specific markets results in a high level of tourist satisfaction, and that in turn, leads to an increase in financial benefits associated with customer satisfaction and loyalty. This research has both theoretical and practical scientific significance. One significant contribution of this research is the development of a model of interrelated motivational factors in the travel decision-making process that enables the identification of the most influential motivational factors in travel decisions. The relationships between the push and pull factors, such as motivations, destination attributes, information sources, expectations and constraints, and their influence on destination choice, were examined. In the present study, a close positive relationship between personal motivations and destination attributes, as well as a significant influence of information sources on expectations and destination choice were found. Such results highlight the importance of properly developed advertising and promotion strategies with special attention to their contents, emphasising particular push and pull factors for particular tourist markets or segments. In addition, the current study identified possible product bundles of tourists’ motivations and destination attributes and segmentation of visitors to Melbourne that might present valuable information for destination practitioners and marketers, as successful matching of push and pull factors is a prerequisite for effective and successful actions on attraction and retention of visitors. Identified similarities and differences between Chinese and non-Chinese samples in terms of their demographic profiles, trip characteristics, motivations for travelling, preferences of destination attributes, information source usage, trip expectations, constraints for travelling, and their evaluation of destination choice criteria provided useful information for developing specifically customised tourist products and services, as well as promotion programs, that are tailored to each market. Moreover, from theoretical perspective, the present study adds new depth to understanding the nature of motivational factors, affecting the travel decision-making process, and causal relationships among them. Thus, the study contributes to advancing both tourist behaviour research as well as tourism decision-making literature. In addition, this research identifies and addresses the gap in empirical research investigating tourists' behaviour patterns across economically and culturally different countries. As comparative motivational research of tourists from China and non-Chinese countries travelling to Australia had yet to be undertaken, this study might be considered important because it provides valuable information for targeting the main source countries for Australia. Such research may be especially valuable in post-COVID times when international borders open up and carefully planned marketing will be needed.
- Description: Doctor of Philosophy
A multi-proxy approach to track ecological change in Gunbower Wetlands, Victoria, Australia
- Authors: Mall, Neeraj
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: The wetlands of the Murray-Darling Basin have come under the threat of a drying climate, the over-allocation of water for irrigation agriculture and widespread catchment disturbance. A synthesis of many paleolimnological assessments undertaken in the upper and lower sections of the Murray floodplain, and the Murrumbidgee, reveal considerable ecological change in wetlands from early in European settlement. The wetlands of the Gunbower Forest lie in the middle reaches of the Murray River. They are located on Gunbower Island that is deemed a wetland of international significance under the Ramsar Convention and an icon site under the Living Murray Initiative. Many Gunbower Island wetlands are located in protected forests, while others are within a zone developed for irrigation, mostly dairy, agriculture. This study analysed the sedimentary records of two wetlands within the forest estate and two within irrigation lands intending to compare long term change in the Gunbower wetlands to studies on floodplains both up and downstream, and to assess the relative impact of regional causes of change and that of local land use. Sediments constitute natural archives of past environmental changes. Sediment records were recovered from four wetlands and radiometric dating and multi-proxy paleoecological techniques were applied to assess how these wetlands have responded to changes in human occupation and other factors, such as climate. Then, extracted sediment cores were taken from Black (core length: 84 cm) and Green (86 cm) Swamps located in the forest, and Taylors (94 cm) and Cockatoo (74 cm) Lagoons were situated amongst dairy farms. In order to reconstruct ecological and water quality changes from the study sites, the cores were analysed using four different analysis techniques, i.e., Itrax-XRF (X-Ray Fluorescence) scanning, Lead-210 (210Pb) dating, Stable isotope and diatom analysis. XRF scanning provided evidence of the elemental composition of the cores. Detrital enrichment in the lower parts of all cores was observed, indicating elevated erosion rates or low water levels. In addition to this, some recent metal pollution was evident with high Cu, Ni and Pb inputs. Stable isotopes provided limited information on the carbon and nitrogen sources. The
- Description: Doctor of Philosophy
- Authors: Mall, Neeraj
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: The wetlands of the Murray-Darling Basin have come under the threat of a drying climate, the over-allocation of water for irrigation agriculture and widespread catchment disturbance. A synthesis of many paleolimnological assessments undertaken in the upper and lower sections of the Murray floodplain, and the Murrumbidgee, reveal considerable ecological change in wetlands from early in European settlement. The wetlands of the Gunbower Forest lie in the middle reaches of the Murray River. They are located on Gunbower Island that is deemed a wetland of international significance under the Ramsar Convention and an icon site under the Living Murray Initiative. Many Gunbower Island wetlands are located in protected forests, while others are within a zone developed for irrigation, mostly dairy, agriculture. This study analysed the sedimentary records of two wetlands within the forest estate and two within irrigation lands intending to compare long term change in the Gunbower wetlands to studies on floodplains both up and downstream, and to assess the relative impact of regional causes of change and that of local land use. Sediments constitute natural archives of past environmental changes. Sediment records were recovered from four wetlands and radiometric dating and multi-proxy paleoecological techniques were applied to assess how these wetlands have responded to changes in human occupation and other factors, such as climate. Then, extracted sediment cores were taken from Black (core length: 84 cm) and Green (86 cm) Swamps located in the forest, and Taylors (94 cm) and Cockatoo (74 cm) Lagoons were situated amongst dairy farms. In order to reconstruct ecological and water quality changes from the study sites, the cores were analysed using four different analysis techniques, i.e., Itrax-XRF (X-Ray Fluorescence) scanning, Lead-210 (210Pb) dating, Stable isotope and diatom analysis. XRF scanning provided evidence of the elemental composition of the cores. Detrital enrichment in the lower parts of all cores was observed, indicating elevated erosion rates or low water levels. In addition to this, some recent metal pollution was evident with high Cu, Ni and Pb inputs. Stable isotopes provided limited information on the carbon and nitrogen sources. The
- Description: Doctor of Philosophy
A patient agent controlled customized blockchain based framework for internet of things
- Authors: Uddin, Md Ashraf
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Although Blockchain implementations have emerged as revolutionary technologies for various industrial applications including cryptocurrencies, they have not been widely deployed to store data streaming from sensors to remote servers in architectures known as Internet of Things. New Blockchain for the Internet of Things models promise secure solutions for eHealth, smart cities, and other applications. These models pave the way for continuous monitoring of patient’s physiological signs with wearable sensors to augment traditional medical practice without recourse to storing data with a trusted authority. However, existing Blockchain algorithms cannot accommodate the huge volumes, security, and privacy requirements of health data. In this thesis, our first contribution is an End-to-End secure eHealth architecture that introduces an intelligent Patient Centric Agent. The Patient Centric Agent executing on dedicated hardware manages the storage and access of streams of sensors generated health data, into a customized Blockchain and other less secure repositories. As IoT devices cannot host Blockchain technology due to their limited memory, power, and computational resources, the Patient Centric Agent coordinates and communicates with a private customized Blockchain on behalf of the wearable devices. While the adoption of a Patient Centric Agent offers solutions for addressing continuous monitoring of patients’ health, dealing with storage, data privacy and network security issues, the architecture is vulnerable to Denial of Services(DoS) and single point of failure attacks. To address this issue, we advance a second contribution; a decentralised eHealth system in which the Patient Centric Agent is replicated at three levels: Sensing Layer, NEAR Processing Layer and FAR Processing Layer. The functionalities of the Patient Centric Agent are customized to manage the tasks of the three levels. Simulations confirm protection of the architecture against DoS attacks. Few patients require all their health data to be stored in Blockchain repositories but instead need to select an appropriate storage medium for each chunk of data by matching their personal needs and preferences with features of candidate storage mediums. Motivated by this context, we advance third contribution; a recommendation model for health data storage that can accommodate patient preferences and make storage decisions rapidly, in real-time, even with streamed data. The mapping between health data features and characteristics of each repository is learned using machine learning. The Blockchain’s capacity to make transactions and store records without central oversight enables its application for IoT networks outside health such as underwater IoT networks where the unattended nature of the nodes threatens their security and privacy. However, underwater IoT differs from ground IoT as acoustics signals are the communication media leading to high propagation delays, high error rates exacerbated by turbulent water currents. Our fourth contribution is a customized Blockchain leveraged framework with the model of Patient-Centric Agent renamed as Smart Agent for securely monitoring underwater IoT. Finally, the smart Agent has been investigated in developing an IoT smart home or cities monitoring framework. The key algorithms underpinning to each contribution have been implemented and analysed using simulators.
- Description: Doctor of Philosophy
- Authors: Uddin, Md Ashraf
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Although Blockchain implementations have emerged as revolutionary technologies for various industrial applications including cryptocurrencies, they have not been widely deployed to store data streaming from sensors to remote servers in architectures known as Internet of Things. New Blockchain for the Internet of Things models promise secure solutions for eHealth, smart cities, and other applications. These models pave the way for continuous monitoring of patient’s physiological signs with wearable sensors to augment traditional medical practice without recourse to storing data with a trusted authority. However, existing Blockchain algorithms cannot accommodate the huge volumes, security, and privacy requirements of health data. In this thesis, our first contribution is an End-to-End secure eHealth architecture that introduces an intelligent Patient Centric Agent. The Patient Centric Agent executing on dedicated hardware manages the storage and access of streams of sensors generated health data, into a customized Blockchain and other less secure repositories. As IoT devices cannot host Blockchain technology due to their limited memory, power, and computational resources, the Patient Centric Agent coordinates and communicates with a private customized Blockchain on behalf of the wearable devices. While the adoption of a Patient Centric Agent offers solutions for addressing continuous monitoring of patients’ health, dealing with storage, data privacy and network security issues, the architecture is vulnerable to Denial of Services(DoS) and single point of failure attacks. To address this issue, we advance a second contribution; a decentralised eHealth system in which the Patient Centric Agent is replicated at three levels: Sensing Layer, NEAR Processing Layer and FAR Processing Layer. The functionalities of the Patient Centric Agent are customized to manage the tasks of the three levels. Simulations confirm protection of the architecture against DoS attacks. Few patients require all their health data to be stored in Blockchain repositories but instead need to select an appropriate storage medium for each chunk of data by matching their personal needs and preferences with features of candidate storage mediums. Motivated by this context, we advance third contribution; a recommendation model for health data storage that can accommodate patient preferences and make storage decisions rapidly, in real-time, even with streamed data. The mapping between health data features and characteristics of each repository is learned using machine learning. The Blockchain’s capacity to make transactions and store records without central oversight enables its application for IoT networks outside health such as underwater IoT networks where the unattended nature of the nodes threatens their security and privacy. However, underwater IoT differs from ground IoT as acoustics signals are the communication media leading to high propagation delays, high error rates exacerbated by turbulent water currents. Our fourth contribution is a customized Blockchain leveraged framework with the model of Patient-Centric Agent renamed as Smart Agent for securely monitoring underwater IoT. Finally, the smart Agent has been investigated in developing an IoT smart home or cities monitoring framework. The key algorithms underpinning to each contribution have been implemented and analysed using simulators.
- Description: Doctor of Philosophy
Agoraphilic navigation algorithm in dynamic environment
- Authors: Hewawasam, Hasitha
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis presents a novel Agoraphilic (free space attraction [FSA])-based navigation algorithm. This new algorithm is capable of undertaking local path planning for robot navigation in static and dynamic environments with the presence of a moving goal. The proposed algorithm eliminates the common weaknesses of the existing navigation approaches when operating in unknown dynamic environments while using the modified Agoraphilic concept. The Agoraphilic Navigation Algorithm in Dynamic Environment (ANADE) presented in this thesis does not look for obstacles (problems) to avoid; rather, it looks for free space (solutions) to follow. Therefore, this algorithm is also a human-like optimistic navigation algorithm. The proposed algorithm creates a set of Free Space Forces (FSFs) based on the current and future growing free space around the robot. These Free Space Forces are focused towards the current and future locations of a moving goal and finally generate a single attractive force. This attractive force pulls the robot through current free space towards the future growing free space leading to the goal. The new free space concept allows the ANADE to overcome many common problems of navigation algorithms. Several versions of the ANADE have been developed throughout this research to overcome the main limitation of the original Agoraphilic algorithm and address the common weaknesses of the existing navigation approaches. The ANADE I uses an object tracking method to identify the states (locations) of moving objects accurately. The ANADE II uses a dynamic obstacle prediction methodology to identify the robot’s future environments. In the ANADE III, a novel controller based on fuzzy logic was developed and combined with the new FSA concept to provide optimal navigational solutions at a low computational cost. In the ANADE III, the effectiveness of the ANADE II was further improved by incorporating the velocity vectors of the moving objects into decision-making. In the ANADE IV, a self-tuning system was successfully applied to the ANADE III to take advantage of the performances of free space attraction-based navigation algorithms. The proposed final version of the algorithm (ANADE V) comprises nine main modules. These modules are repeatedly used to create the robot’s driving force, which pulls the robot towards the goal (moving or static). An obstacle tracking module is used to identify the time-varying free spaces by tracking the moving objects. Further, a tracking system is also used to track the moving goal. The capacity of the ANADE was strengthened further by obstacle and goal path prediction modules. Future location prediction allowed the algorithm to make decisions by considering future environments around the robot. This is further supported by a self-tuning, machine learning–based controller designed to efficiently account for the inherent high uncertainties in the robot’s operational environment at a reduced computational cost. Experimental and simulation-based tests were conducted under dynamic environments to validate the algorithm. Further, the ANADE was benchmarked against other recently developed navigation algorithms. Those tests were focused on the behaviour of the algorithm under challenging environments with moving and static obstacles and goals. Further, the test results demonstrate that the ANADE is successful in navigating robots under unknown, dynamically cluttered environments.
- Description: Doctor of Philosophy
- Authors: Hewawasam, Hasitha
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis presents a novel Agoraphilic (free space attraction [FSA])-based navigation algorithm. This new algorithm is capable of undertaking local path planning for robot navigation in static and dynamic environments with the presence of a moving goal. The proposed algorithm eliminates the common weaknesses of the existing navigation approaches when operating in unknown dynamic environments while using the modified Agoraphilic concept. The Agoraphilic Navigation Algorithm in Dynamic Environment (ANADE) presented in this thesis does not look for obstacles (problems) to avoid; rather, it looks for free space (solutions) to follow. Therefore, this algorithm is also a human-like optimistic navigation algorithm. The proposed algorithm creates a set of Free Space Forces (FSFs) based on the current and future growing free space around the robot. These Free Space Forces are focused towards the current and future locations of a moving goal and finally generate a single attractive force. This attractive force pulls the robot through current free space towards the future growing free space leading to the goal. The new free space concept allows the ANADE to overcome many common problems of navigation algorithms. Several versions of the ANADE have been developed throughout this research to overcome the main limitation of the original Agoraphilic algorithm and address the common weaknesses of the existing navigation approaches. The ANADE I uses an object tracking method to identify the states (locations) of moving objects accurately. The ANADE II uses a dynamic obstacle prediction methodology to identify the robot’s future environments. In the ANADE III, a novel controller based on fuzzy logic was developed and combined with the new FSA concept to provide optimal navigational solutions at a low computational cost. In the ANADE III, the effectiveness of the ANADE II was further improved by incorporating the velocity vectors of the moving objects into decision-making. In the ANADE IV, a self-tuning system was successfully applied to the ANADE III to take advantage of the performances of free space attraction-based navigation algorithms. The proposed final version of the algorithm (ANADE V) comprises nine main modules. These modules are repeatedly used to create the robot’s driving force, which pulls the robot towards the goal (moving or static). An obstacle tracking module is used to identify the time-varying free spaces by tracking the moving objects. Further, a tracking system is also used to track the moving goal. The capacity of the ANADE was strengthened further by obstacle and goal path prediction modules. Future location prediction allowed the algorithm to make decisions by considering future environments around the robot. This is further supported by a self-tuning, machine learning–based controller designed to efficiently account for the inherent high uncertainties in the robot’s operational environment at a reduced computational cost. Experimental and simulation-based tests were conducted under dynamic environments to validate the algorithm. Further, the ANADE was benchmarked against other recently developed navigation algorithms. Those tests were focused on the behaviour of the algorithm under challenging environments with moving and static obstacles and goals. Further, the test results demonstrate that the ANADE is successful in navigating robots under unknown, dynamically cluttered environments.
- Description: Doctor of Philosophy