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Modelling, System-Level Control, Fault Protection, and Power Flow Analysis in Medium-Voltage DC Systems
No full textMedium-voltage DC (MVDC) systems, typically operating between ±0.75 kV and ±50 kV, are emerging as a promising solution for modern power networks. Their potential applications span sub-transmission, distribution, and collection networks, providing enhanced support for the integration of regional renewable energy sources (RESs) and energy storage systems (ESSs). With the rapid growth of DC loads such as electrified transportation and data centers, MVDC systems are increasingly viewed as a viable alternative to traditional AC infrastructure. Furthermore, the integration of DC/DC and AC/DC converters in MVDC systems offers enhanced control flexibility compared to conventional AC architectures. This allows precise power regulation for wind farms, photovoltaic (PV) plants, ESSs, and various DC loads, improving system stability under fluctuating conditions and facilitating more efficient power dispatch.
Three critical challenges facing MVDC systems are identified in this thesis: 1) the devel opment of flexible system-level control strategies under diverse operational scenarios involving RESs, ESSs, and various types of loads; 2) the design of fault handling and fault ride-through schemes for converters used in distribution networks; and 3) the development of fast and accurate power flow (PF) computation methods for both grid-connected and islanded MVDC distribu tion systems operating under different converter control modes, with further extension to hybrid AC/MVDC systems. In addition, five specific research gaps in MVDC distribution systems are addressed. Firstly, existing droop control and adaptive droop control (ADC) strategies fail to consider the coordinated participation of ESSs, limiting their ability to regulate dc voltage and power sharing. Secondly, there is a lack of effective protection schemes specifically designed for valve-side single-phase-to-ground (SPG) faults in modular multilevel converter (MMC)-based MVDC networks. Thirdly, steady-state power distribution characteristics in hybrid AC and multi-terminal MVDC (AC/MT-MVDC) systems remain insufficiently explored, posing chal lenges for system-level planning and optimization. Fourthly, conventional PF algorithms are not well-suited for islanded MVDC and MVAC microgrids. Finally, existing data-driven PF methods often struggle to achieve both high accuracy and robust generalization across diverse MVDC operating scenarios.
Beginning from the exploration of possible network configurations for MVDC systems, this work presents typical system architectures, key converter requirements, and protection strategies at both the system and converter levels, while identifying potential applications and develop ment opportunities in Australia. It further introduces PF modelling approaches for MVDC and interfacing AC systems, alongside the operation principles and electromagnetic transient (EMT) models of symmetrical monopolar and bipolar MMCs. A Th´evenin/Norton equivalent model is developed for detailed fault analysis, and an average-value model is adopted for MT-MVDC system studies. To enhance system resilience, an ADC scheme is proposed to better utilize VSC overloading capability, coordinated through the operational status of heterogeneous ESSs. Two novel control loops are introduced to manage excess power dynamically and ensure effective post-disturbance recovery.
Two numerical (model-driven) PF algorithms are presented to solve the PF problems in hybrid AC/MT-MVDC systems and standalone MVDC & MVAC microgrids, respectively. For hybrid AC/MT-MVDC systems, a sequential Fibonacci search-based Newton-Raphson (FSNR)-based PF method with uniform bus type definitions is introduced, along with a zero-error steady state post-event calculation approach to efficiently determine power distribution following system disturbances. For standalone MVDC microgrids, a generalized accelerated iterative search (AIS)-based algorithm is developed to overcome the limitations of traditional methods under variable slack bus voltage, while an accelerated external search loop-based NR (AESL-NR) PF algorithm is proposed for the MVAC microgrids to deal with variations in both slack bus voltage and frequency.
Building on the model-driven PF algorithms, two data-driven approaches, using physics in formation guidance in fully convolutional networks (FCNs), are further proposed for the rapid PF estimation of MT-MVDC distribution systems. The first method, a physics-informed FCN (PI-FCN), employs a channel combination layer and a physics-based input reformulation strat egy to enhance prediction accuracy and generalization under varying topologies and operating conditions. The second method, a physics-embedded FCN (PEFCN), incorporates a physics operation layer and redesigned loss functions to suppress outliers and improve robustness. Both methods demonstrate strong performance across diverse scenarios, offering valuable strategies for accurate and efficient PF estimation in practical MVDC networks
Content Analysis and Generation
No full textThis thesis tackles the connected challenges of content analysis and content generation through the development of explainable models for complex datasets. Current approaches often miss hidden information and fail to capture causal progression, limiting their ability to produce coherent, meaningful content. For image generation, creating effective prompts remain another bottleneck, which this work addresses using Large Language
Models (LLMs) for prompt optimisation. These tasks are chosen because, together, they confront the core problem of bridging deep content understanding with the generation of high quality, explainable outputs. Accordingly, this thesis focuses on three main tasks: (i) Developing content models for identifying engaging features using Significant Feature Lasso (SFLASSO), (ii) Proposing content models for generating coherent story endings, and (iii) Designing a prompting approach for generating social media images. To support explainability, this thesis proposes content models based on SFLASSO, which identifies the most significant features influencing a target outcome. It also introduces a variant called SFLASSO-SI, which performs selective inference for a conservative significance test. Furthermore, a two-stage anchoring-and-adjustment approach is proposed: in the first stage, the optimal penalisation value is identified along the regularisation path; in the second stage, features with high Variance Inflation Factor (VIF) are removed to improve the quality of the selected features. For story generation, this thesis introduces content models that generate transitional commonsense sentences between adjacent context sentences, thereby revealing the hidden narrative. By modelling soft causal relations grounded in everyday commonsense knowledge, the approach enhances the causal coherence of generated stories. Causal reasoning and dependency parsing are used to capture long-range
text dependencies, and multi-level Graph Convolutional Networks, along with LLMs, are employed to provide enriched contextual representations. Finally, the thesis presents a prompting approach for generating social media images. While prompt engineering has recently gained attention, most research focuses on text and reasoning. In contrast, this work demonstrates that prompt-aided image generation can outperform images designed by human experts. State-of-the-art models such as Midjourney, DALL·E 3, and Stable Diffusion XL are utilised to generate images from prompts
Exploring the context of Governance, Structure and Evaluation of Australian Infection Prevention and Control
No full textBackground
Infection prevention and control (IPC) is critical to the reduction of healthcare associated infections (HAIs). The COVID-19 pandemic attracted widespread attention and highlighted the importance of IPC programs. This thesis examines Australian IPC programs to assess governance, organisational structure, strategy, and program elements aligned with World Health Organization (WHO) core components, and evaluation.
Method
Three research studies have been conducted, involving participants with experience and expertise in IPC and HAI across the eight Australian jurisdictions. Study one, compared jurisdictional IPC programs using a survey and document analysis. Study two, evaluated the COVID-19 IPC Response and Escalation Framework, employing an online, cross-sectional survey. Study three, investigated the governance, strategy and organisational structures that should underpin Australian IPC programs. The investigation involved a modified Delphi study involving document analysis, questionnaire survey, open group discussion, and expert panel review.
Results
Key findings from the jurisdictional comparison (study one) found variability across governance, organisational structure, staffing, competency, resources and focus on HAI compared with IPC. Jurisdictional programs highlighted a lack of governance and any organisational structure framework. Four of eight jurisdictions did not have a formal statewide IPC program. Australian jurisdictions reported partial compliance with WHO core components for IPC. The evaluation of the IPC response and escalation framework in NSW (study two) determined that a risk assessed framework for implementing IPC strategies was an effective IPC management tool (93%) and was easily adopted by clinicians (85%). Stakeholders emphasised the importance of pandemic preparedness aligned with governance and organisational structure for effectiveness. The three highest priority actions for strengthening future pandemic preparedness are increasing IPC resourcing, embedding IPC specific information into state health and emergency response strategic planning, and establishing standardised, transparent IPC governance structures. Investigations of IPC programs (study three) which surveyed 226 IPC representatives from across Australia, identified substantial jurisdictional variability in IPC program governance and reporting structures. Executive engagement was reported as critical for overall effectiveness and culture driven IPC. Varied staffing, resources and differing priorities contribute to independent jurisdictional planning and operations. Governance arrangements were most commonly situated within patient safety (32%), followed by Communicable (Infectious) Diseases (22%) and Public Health (20%). The remaining programs were distributed across a range of other structures, including clinical governance, policy and regulation, aged care, nursing, or operated by sole or independent practitioners. There is no aligned local, state and national governance and organisational structure framework in place, however there is widespread support for IPC programs as integral to the Australian Centres for Disease Control.
Conclusion
The findings underscore the need for a national governance framework that can be applied consistently across local, state, and national levels. Essential components include: strong IPC leadership and expertise; a consistent and transparent organisational structure; and, executive engagement and adequate resourcing.
The proposed framework aligns with WHO core components and supports pandemic preparedness. The AusCDC is positioned as the overarching governance authority, working in collaboration with the ACSQHC to ensure national consistency and accountability in IPC programs
Autonomous Orbit Determination of Lunar Navigation Satellites Based on Inter-Satellite Links
No full textTo support a future lunar navigation satellite system, this study proposes and validates an inter–satellite link (ISL) –centric framework for autonomous orbit determination. The simulation employs one–way range and range–rate satellite–to–satellite tracking (SST) between relay satellites in distant retrograde orbits (DROs) and navigation satellites in elliptical lunar frozen orbits (ELFOs), with a customised unscented Kalman filter that estimates their orbital and clock states without direct ground support to the navigation satellite. Performance is assessed under both a simplified circular restricted three–body problem (CR3BP) model and a high–fidelity dynamic model; first–order uncertainty from the relay satellite is introduced in the filter to improve its adaptability, robustness, consistency and hence overall estimation performance. Monte Carlo method and NEES/NIS checks are conducted for validations. In the CR3BP case, three evenly phased DRO relays substantially accelerate convergence and improve accuracy; the navigation satellite attains ~11 m 3–D position and 1.58 mm/s velocity accuracy, with position performance reaching that of the relays. In the high–fidelity case, two scenarios are examined: (i) a 2–day initial ground–tracking handover followed by SST only, and (ii) SST–only throughout, showing that the handover strategy expedites convergence and stabilises estimation, yielding ~1 km 3–D position and 10 mm/s velocity accuracy for the navigation satellite. Sensitivity analyses highlight the roles of measurement baseline, update interval, and filter tuning. Overall, the approach is feasible and scalable, laying groundwork for a resilient, autonomous cislunar positioning, navigation and timing (PNT) infrastructure and related deep–space missions
Social Technology Use and Loneliness: Exploring Online and Offline Patterns and Preferences in Young, Middle-Aged, and Older Adults
No full textThis study examines socialisation patterns, preferences, and the relationship between social technology use and loneliness in young, middle-aged, and older adults. Survey data was collected from 1079 adults aged 18–90 (M age = 53.5, SD = 18.64). ANOVA was used to make comparisons between age groups while Spearman’s correlation and binary logistic regression were used to examine associations between social technology use and loneliness. The results show varying patterns of social technology use and associations with loneliness across age groups. For middle-aged and older adults, in-person socialization, phone calls, and texting (older adults only) reduced odds of loneliness by 16% to 30%. For young and middle-aged adults, the number of virtual contacts was associated with decreased loneliness, while for older adults only face-to-face interactions were associated with reduced loneliness. These findings highlight generational preferences in social contact and reinforce the importance of face-to-face interactions for alleviating loneliness. However, they also provide insights into virtual connections that are effective in reducing loneliness when in-person interactions are not available
HIV, viral hepatitis and sexually transmissible infections among people from culturally and linguistically diverse backgrounds in Australia: Enhanced surveillance report
Full text linkBA v The King and the law of home
Full text linkIn BA v The King the High Court decided, by majority, that the offence of breaking and entering did not lie where a man kicked down a door and assaulted his former partner, because the man was still a co-tenant. The judgments show a profound difference in analytical frameworks, with the majority guided by property rights, and the minority guided by a concept of home. In light of criticism of the underdevelopment of the legal concept of home, this contemporary comment critically unpacks the legal decisions taken by the prosecution and judges through the proceedings culminating in BA v The King. The comment then considers recent progress and shortcomings in tenancy laws relating to the ending of co-tenant relationships and domestic and family violence in New South Wales and other Australian jurisdictions
Developing and validating a positive mental health scale for the global south construction industry: the construction industry positive mental health inventory (CI-PMHI)
Full text linkPurpose: Promoting positive mental health is increasingly being encouraged as the focus of research and policies on the mental health of construction personnel. Most measures of mental health, however, typically use negative indicators such as depression and anxiety and are not specifically developed for the construction workforce, especially those with a Global South background. These limitations have made it challenging to measure construction personnel’s positive mental health. The purpose of this study was, therefore, to develop a scale for measuring the positive mental health of construction personnel with a Global South background. Design/methodology/approach: Guided by Keyes’ two-continua model of mental health, the study objectives were addressed through a mixed-methods study using the case of Ghana. Qualitative data collected from eight key stakeholder groups using 16 interviews and two rounds of focus group discussions were analysed thematically. Quantitative data were obtained through a survey of 425 construction personnel and analysed using confirmatory factor analysis and correlation analysis. Findings: Thematic analysis revealed a four-dimensional structure of positive mental health, namely, emotional, psychological, social and spiritual. Confirmatory factor analysis and correlation analysis of the results indicated good instrument validity and reliability. Originality/value: Existing measures of positive mental health are based on a three-dimensional model, i.e. emotional, social and psychological well-being. By including spiritual well-being, this study proposes a four-dimensional measurement model as a more comprehensive and promising measure to use in surveys of positive mental health among the construction workforce, especially those with a Global South background, and to develop suitable interventions for them
Nanotechnology innovations for neurodegenerative disease biomarker detection and nitric oxide therapeutics
Full text linkNanotechnology has revolutionized biomedical research, providing innovative solutions for both disease detection and therapeutic delivery. Building on these advancements, this PhD thesis focuses on utilizing nanomaterials to not only enhance the detection of neurodegenerative diseases, specifically Alzheimer's disease, but also improve the delivery of nitric oxide (NO) for therapeutic purposes.
Alzheimer’s disease (AD) presents significant challenges due to its complex pathologies and difficulties in achieving early and accurate diagnosis. To address this, the first project presents the development of a nanozyme-based colorimetric sensor for the rapid and sensitive detection of AD biomarkers. By synthesizing a zirconium-based metal-organic framework, UiO-66-NH2, and doping it with iron, copper, or platinum, the catalytic properties of the nanozymes were significantly enhanced. Among these, platinum-doped UiO-66-NH2 exhibited the highest performance, detecting amyloid-beta (Aβ) with a limit of 2.76 nM within 5 minutes, highlighting its potential as a rapid diagnostic tool for AD.
Shifting focus from diagnostics to therapeutics, the second project investigates the stability of NO donors, specifically S-nitrosothiols (RSNOs), under diverse laboratory and physiological conditions. NO is a potent molecule that can reduce infections by preventing bacterial growth and biofilm formation. Understanding the stability profiles of NO donors is crucial, as it impacts the release dynamics of NO, which has implications for their use in various medical applications. Building on this, the third project explores the development of catheter nanocoatings to enhance the delivery of NO from an RSNO, specifically S-nitrosoglutathione (GSNO). A 'one-pot' synthesis method was used to apply a NO-generating biocompatible coating onto polyvinyl chloride (PVC) tubes using tannic acid and selenocystamine. The coating ensures a tunable, sustained NO flux rate at 5 to 70 × 10-10 mol cm−2 min−1 for at least 3 days, offering a promising strategy to reduce inflammations associated with medical devices.
Collectively, this thesis highlights the potential of nanomaterials in advancing point-of-care diagnostics and therapeutic delivery systems. These innovations can lead to the development of the next generation of biomedical devices, offering new pathways for clinical applications
Curating the Public Domain - Care and Country
No full textA recent shift in curatorial approaches to public space reflects Australia’s growing appreciation and respect for threatened natural environments and First Nations cultures and encapsulates the original meaning of the word ‘curator’ — to care