85000 research outputs found
Sort by
Preprint: Unpacking previous experience: understanding how wildfire experiences shape risk perception and action
No full textPrevious experience with disasters is assumed to uniformly influence risk perceptions and the adoption of protective actions like mitigation and evacuation behaviour. Yet empirical evidence remains inconsistent, and the reason why is not well understood. As climate change intensifies the frequency and severity of disasters, at-risk communities are more likely to experience repeated disaster exposure over shorter time frames. Therefore, understanding how previous experience shapes risks perceptions and protective actions is critical to ensuring disaster resilience. Using a systematic review methodology, we identify studies (n=26) that explores the effect of previous experience of wildfires (bushfires) on risk perception and protective actions (from 2003-2024). We found that previous experience is not consistently conceptualised or operationalised; there are inconsistent findings for the relationship between previous experience and risk perceptions, yet there is greater, positive consistency in findings between previous experience and protective action. We propose there are three possible pathways that previous experience is influencing protective action: either directly, through a cognitive path (e.g., risk perceptions), or through a coping path (e.g., self-efficacy), which challenges existing models. We outline future research opportunities to improve field level understanding of previous experience of wildfires and its impact on risk perceptions and protective action.</p
Distribution of Emerging Contaminants in the Aquatic Environments of Melbourne, Australia: PFAS and Synthetic Musks
No full textWaterways are experiencing growing impacts from chemical pollution; however, effective management of this issue is hindered by a lack of sufficient scientific data. Therefore, emerging contaminants (ECs) with the potential to harm the environmental and limited environmental occurrence data, including per- and poly-fluorinated alkyl substances (PFAS) and synthetic musks (SMs) were selected to study for their environmental occurrence in the greater Melbourne area (GMA), Australia. The distribution of these compounds across urban areas is not well understood, nor is their potential input from industrial and urban sources. SMs lack validated quantitative analytical methods and have been scarcely studied in Australia, with no prior research conducted in the GMA. In contrast, a small number of PFAS are currently quantifiable. The primary aims of this research were to determine the urban background concentrations of 33 PFAS and 11 SMs in environmental surface waters, examine their distribution across different land-use types, and to develop a method for quantifying SMs. To accomplish this, surface water samples were collected from sites selected based on their predominant catchment land-uses, identified using Geographic Information System (GIS) mapping, which comprised of residential, industrial, municipal wastewater treatment plants (WWTPs), and rural. In Chapter 3, a survey of 33 PFAS was conducted in surface water and sediment samples from 65 sites with varying land-uses across the GMA. Urban background concentrations of PFAS were determined, along with their associations to different land-use types. PFAS were detected at 98 % of sites, suggesting widespread diffusion from common anthropogenic sources. Elevated concentrations of perfluoroalkyl sulfonic acids (PFSAs) including PFOS were found in industrial areas, indicating their ongoing use by industries. The perfluoroalkyl carboxylic acids (PFCAs) including PFOA, were evenly distributed across the urban environment, suggesting that PFCAs and their precursors are used throughout urban areas and subject to atmospheric diffusion. The short-chain PFCA, PFBA was detected in both urban and rural areas, demonstrating its high propensity for atmospheric dispersal. This study confirms the broad urban presence of three major PFAS classes—FTSs, PFSAs, and PFCAs—and highlights the need for regulatory and industrial efforts to prioritise their reduction. To enable the quantification of synthetic musks (SMs) in surface waters, in Chapter 4, an analytical method was developed and validated to quantify 11 SMs using solid phase extraction (SPE) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). The SM compounds were selected based on their likely current use (i.e., those with high production volumes and previously reported in the literature), potential harm to aquatic ecosystems, and the availability of analytical standards. They included seven polycyclic musks (PCMs), three nitro musks (NMs), and one macrocyclic musk (MCM). Experimental parameters were optimised to maximise analyte recoveries during extractions from surface waters using Oasis hydrophobic-lipophilic balance solid phase extraction (HLB SPE) cartridges. This included optimisation of elution solvents, cartridge drying method, and matrix water pH and salinity. Laboratory handling conditions were also investigated, which included the determination of recoveries from nitrogen blowdown and long-term sample storage. The GC-MS/MS method was optimised for injection solvent, injection volume, column temperature program, multiple reaction monitoring (MRM) transitions, collision energies (CEs), and MS dwell times. The method quantification limits (MQLs) ranged from 2 to 13 ng/L, and all analytes showed acceptable linearity (R² > 0.99). Matrix-matched corrected recoveries ranged from 80–120 % across the linear range. Validation experiments for intra- and inter-day precision indicated expanded uncertainties (U' at 95 % confidence with a coverage factor of 2) of 27-44 %, well below the acceptable limit of 50 % as defined from EU proficiency tests and outlined in SANTE/11312/2021. This method provides a solid foundation for further optimisation, validation, and analysis of SMs in environmental samples. As SM are rarely included in monitoring programs and are often only investigated in wastewater impacted environments, Chapter 5 reported the associations of SMs to land-uses using data obtained from a survey of surface waters from 25 sites in the GMA. This used the validated extraction and analysis methodology described in Chapter 4. Passive samplers collected during the sampling campaign enabled the production of additional semi-quantitative data, revealing that a greater number of SMs were present (seven) than was detected in the grab water samples (four). The SMs galaxolide, tonalide, cashmeran, celestolide, traseolide, phantolide and musk ketone were detected in urban waterways. Galaxolide was detected at the highest concentrations of all SMs (maximum water concentration = 1553.84 ng/L), with treated wastewater as the major source to the urban environment, although residential areas were also a major source. Tonalide was found across the study area, suggesting widespread atmospheric transport. Dissolved cashmeran was detected at 60 % of residential areas, suggesting it may have entered waters directly from domestic activities. Musk ketone which is internationally banned in cosmetics was prevalent in industrial areas indicating the source may be non-cosmetic fragrances. Findings presented in Chapter 5 illustrate that while wastewater is an important source of SMs, especially galaxolide, residential areas and industrial areas are also contributing to urban pollution from a range of SMs and that they may have moved between catchments atmospherically. The presence of both PCMs and NMs across the urban environment highlights the need for targeted regulatory actions and reduction strategies to mitigate their environmental impact. This work increases analytical capabilities for SMs and provides background concentration data for both PFAS and SMs. These findings are instrumental in guiding future monitoring efforts and in establishing environmentally relevant toxicity thresholds. Although the present research focused on 33 PFAS and 11 SMs, the potential for additional ECs is vast, with thousands of PFAS remaining unexamined. Consequently, the chemical pollution reported in these studies is likely to be an underestimated. Further development and application of analytical techniques are recommended, such as the use of Total Organic Fluorine (TOF) testing to measure total PFAS, and Quadrupole Time-of-Flight (Q-TOF) mass spectrometry to identify other ECs. Given the evolving trends of chemical pollution in the environment, continuous monitoring is advised to guide effective management strategies.</p
The challenges of Safety-Critical Certification of Reinforcement Learning Agents
No full textThe aerospace industry's adoption of autonomous systems mandates reliable, safe, and efficient solutions within deterministic safety-critical workflows. This thesis investigates the challenges inherent to certification of autonomous systems applications based on artificial intelligence for Aerospace and Defence. This research is motivated by the need for Aerospace and Defence systems operating autonomously while adhering to stringent safety standards. The methodology involves utilising state-of-the-art AI systems, particularly reinforcement learning, integrated into a comprehensive Autonomous Systems stack. Reinforcement learning has been proven to generalise problems in large state-spaces, which is exponentially difficult for deterministic methods, but the question still lies in its ability to function within large state-spaces which are also high-dimensional (large number of possible actions). A sizeable portion of this research is dedicated to the application of novel policy-based reinforcement learning algorithms to test its efficiency in real world implementations. Furthermore, it investigates the implications of sparse rewards and intrinsic curiosity-driven modules within the policy-based approach and how well it generalises to more complex applications. The incorporation of FlightGoggles, a photorealistic UAV platform, and the SpaceX Crew Dragon simulator, enables the practical implementation and demonstration of different developed autonomous systems within high-dimensional computer vision processing scenarios. It also provides a novel implementation of an Autonomous Analyst by embedding of human knowledge expertise into reinforcement learning training workflows via Propositional Logic Networks while leveraging an Actor-Checker architecture to provide a reasonable Safety case for certification of non-deterministic agents. This multi-domain approach provides all the base knowledge needed to formulate and propose a novel solution for one of the most dominant challenges in the field of Artificial Intelligence: the disproportionate challenge of certifying non-deterministic systems through traditional certification workflows, such as DO-178C, which presents the most demanding requirements around traceability and success rates for mission-critical applications. By incorporating several of the most utilised artificial intelligent applications cohesively to execute in critical mission scenarios, a practical application is constructed providing realistic metrics and workflows for the analysis and definition of a safety case argument for the use of reinforcement learning agents in safety-critical settings. In doing so this research seeks to answer a question yet to be responded by industry and academia and contribute to the advance of the discipline of Artificial Intelligence into safety-critical applications.</p
Government CEO pay regulation and corporate innovation performance: The role of CEO’s career horizon and shareholding
No full textThis study investigates the effect of government pay policy for chief executive officer’s (CEO’s) compensation on corporate innovation (CI). Furthermore, it explores the role of the CEO’s career horizon and shareholding in this nexus. Utilizing the difference-in-differences method to analyze Chinese-listed state-owned enterprises from 2010 to 2020, the baseline findings indicate that government pay policies have had a negative impact on CI. In addition, CEOs with shorter career horizons and higher shareholding demonstrate an enhanced ability to counteract the adverse effects of pay policy, thereby sustaining high levels of innovation. Our findings indicate a necessity for regulatory bodies to re-evaluate mandated constraints on CEO compensation. These restrictions lead to a decline in firm innovation, ultimately affecting shareholder interests. Importantly, the study conclusions remain robust even after rigorous analysis using parallel trend assumptions, propensity score matching, alternative pay policy and innovation metrics, and placebo tests.</p
Delivering Demand Response Services to the Power Grid via Smart Building Load Flexibility
No full textPower systems worldwide face stability challenges as renewable energy integration transforms electricity networks. Renewable energy sources’ fundamentally different operation, intermittency, and physics versus traditional synchronous generators primarily drive these challenges. Ancillary services, traditionally delivered by synchronous generators as a by-product of electricity production, help keep power system voltage and frequency within bounds. However, renewable energy sources can complicate their provision. Demand response is a power balancing method that encourages customers to adjust their energy usage in response to price signals. Buildings are particularly attractive participants owing to their significant energy consumption and high flexibility in energy control. Digitalisation and advances in communications technologies, artificial intelligence, and machine learning enhance buildings’ potential for demand response provision. This paper explores demand response service provision via smart building load flexibility. We show how building energy flexibility can be characterised by power adjustment direction, capacity, availability, predictability, and response time. Key flexibility sources include shiftable loads like electric vehicles, non-shiftable loads such as lighting, and controllable loads like heating and ventilation. Electric vehicles—particularly those with vehicle-to-grid technology—and heating, ventilation, and cooling systems are the most attractive building loads for demand response owing to their flexibility, response time, and duration. We also analyse ancillary service frameworks in Australia, Hong Kong, and Mainland China. Australia’s well-established market supports demand response projects like vehicle to-grid initiatives. Hong Kong and Mainland China are in earlier development stages, with opportunities for modernisation and expanded market frameworks.
Promising technologies for enhancing grid support include smart sensors, loads and inverters, as well as artificial intelligence. They can help optimise building energy management, facilitate real-time control, and provide predictive capabilities from historical data. Solar façades may also help buildings participate more in grid service provision, while advanced building insulation materials can help improve energy efficiency. The paper concludes by examining the regulatory and policy landscapes across Australia, Hong Kong, and Mainland China and posing open industry and research questions. In Australia, reform has sought to drive greater flexibility, reform trader services, and provide fit-for-purpose consumer protections. Meanwhile, Mainland China is implementing more demand-side management measures, guidelines, and policies to enhance energy efficiency and grid stability through demand response uptake. Hong Kong has only implemented a few demand-side management measures—it has yet to fully develop direct regulations or policies addressing building load flexibility engagement in grid support ancillary services. Effective regulations, policies, and market mechanisms will be critical for unlocking building load flexibility. Overall, advancements in electric vehicles, artificial intelligence, smart energy conversion, and digitalisation provide substantial opportunities for leveraging smart building load flexibility for demand response services to power grids.</p
Breaking Stiffness‐Tunability Trade‐offs in Metamaterials: a Minimal Surface Guided Hybrid Lattice Strategy
No full textA longstanding trade-off between stiffness and tunability has significantly constrained the multifunctional potential of architected metamaterials. Here, a generalizable design framework is introduced that integrates shell- and plate-based lattice architectures via a spatially compensated Boolean fusion strategy. The design enables tunable architectures with optimized mechanical robustness. The capability is demonstrated through two representative configurations: one based on Primitive TPMS and one on IWP TPMS, each fused with simple cubic plate lattices. The resulting structures are fabricated with high geometric fidelity using PolyJet printing and evaluated across multiple scales using homogenization, quasi-static compression testing, and finite element analysis. Compared with similarly ultrastiff plate lattices, the hybrid structure achieves a 213.98% increase in the tunable range of effective elastic modulus. The hybrid lattices reach 137.34% and 110.84% of the Hashin-Shtrikman upper bound for Young's modulus at relative densities of 0.33 and 0.34, respectively. Compared to single lattices, the hybrid designs show significant improvements: ultimate stress increased by up to 690% and specific energy absorption increased by 110%. The proposed metamaterials offer excellent tunability and mechanical performance, providing the flexibility to tailor structural behaviors for diverse applications such as biomedical engineering, acoustic isolation, and intelligent infrastructure systems.</p
Fair Event Influence Analysis in Social Networks
No full textSocial network platforms have become an important tool to analyse the influence spread of real-world events. Two core challenges remain in event influence analysis: how to model an event’s propagation within a social network and how to optimize the propagation to maximize user-event engagement. Existing information propagation models deliver a large volume of irrelevant messages to users with good information access, while rarely activating users who lack sufficient information access. This unequal information access exacerbates the disparity of influence received by individual users, resulting in a fairness issue. Existing influence maximization solutions focus on activating the maximal number of users for a piece of information, but they lack adaptability to event-related information in a streaming environment where the content or context of an event evolves over time. Overlooking this dynamic nature of events leads to inaccurate influence estimation for users, which further hinders the effective propagation of events. Furthermore, existing solutions lack explanations for their results. Both influence and fairness are evaluated by predefined score functions. However, it is difficult for audiences without prior knowledge of social influence analysis to comprehend the implications of such scores. Consequently, in this thesis, two main contributions are made to analyse events’ influence in social networks: maximizing fair event-aware influence in microblogs and visualizing the spread of event influence.We propose a Fair Event-aware Influence Maximization (FEIM) framework, which allows the influence analysis system to coordinate message propagation in an event-sensitive and fair manner. Specifically, we first build an event-aware social graph that dynamically captures the probability of each user being activated by different event messages. Then, a novel Ensemble Activation Forest (EAF) model is developed to enable an equal number of messages sent to each receiver in the information diffusion process. Finally, we design a set of optimization strategies, including a Dijkstra-like Fast Reachability Calculation (DFRC) algorithm, a Greedy Reachability-based Seed Selection (GRSS) algorithm and a Fair Edge Selection (FES) algorithm to improve the effectiveness and efficiency of fair event propagation. Extensive experiments are conducted to prove the superiority of our FEIM framework.In our second study, we examine three case studies to visualize the event propagation of FEIM and two state-of-the-art Influence Maximization (IM) methods. Each case follows a consistent procedure. First, for each method, we construct a propagation graph using shared raw data to illustrate how the method perceives and responds to event-related content. Second, we depict the message transmission along each edge of these graphs during event propagation as planar figures to clearly and intuitively showcase influence spread results and fairness issues. Specifically, in the case of Nepal Earthquake 2015, we construct propagation graphs using social messages about sub-events “food” and “blood”; in the case of Texas Flood 2015, we investigate the propagation paths of sub-events “usa” and “water”; in the case of World Cup 2014, we focus on sub-events “team” and “game”.</p
For Louise Nevelson
No full textBackground This research investigates the performative relationship between language and object-making, examining how written statements function as invocations that activate sculptural works. Drawing parallels between magical practice and research frameworks, the work explores how words combined with objects shape meaning and reality—analogous to how research statements construct relationships with artworks. The research engages with established scholarship connecting art and occult practices, including Katy Siegel's "The Black Wallpaper: Louise Nevelson's Gothic Modernism," and recent curatorial investigations such as the State Library's 'The Creative Act' (examining spiritual connections and rituals in artistic practice), McLellan Gallery's 'Eternal Oblivion: death & the afterlife', and Buxton Contemporary's 'The Veil' (exploring uncanny and supernatural qualities in contemporary art). This positions the work within broader discourse on how contemporary sculpture engages with esoteric knowledge systems and the performative function of institutional language. Contribution The sculpture contributes to understanding of cyclical making processes and material transformation through an ongoing practice of creating, destroying, and remaking works from scavenged plastic. This generates a self-cannibalising system where sculptures provide their own detritus for subsequent iterations—a sustainable, low-cost process that challenges conventional notions of the finished artwork. The work functions as a conceptual repository for investigating Louise Nevelson's assemblage practice and relationships between art and occult traditions, while simultaneously interrogating how institutional frameworks (research statements, exhibition contexts, collection acquisitions) operate as contemporary forms of invocation that determine an object's meaning and value. This contributes to discourse on materiality, process-based practice, and the performative dimensions of research documentation in creative practice. Significance The work's significance is evidenced through selection as a finalist in The Deakin University Contemporary Small Sculpture Award (shortlisted from approximately 300 entries to 40 finalists), judged by Professor Emeritus Barbara van Ernst and Dr. Dan Wollmering. The sculpture's acquisition by Deakin University Art Collection represents institutional validation equivalent to peer review processes, demonstrating the work's contribution to contemporary sculpture discourse. The 8 week exhibition period at Deakin University Art Gallery provided extended public engagement and critical reception, establishing the work's relevance to ongoing conversations about material practice, cyclical processes, and the intersection of contemporary art with esoteric knowledge systems.</p
Communication Studies and Pedagogy: Challenges, Innovations, Solutions
No full textCommunication Studies programs in Australian Higher Education face new and evolving pedagogical challenges as they respond to the increasingly diverse and rapidly evolving technologically world we live in. The prevalence of generative AI usage, for instance, has disrupted both the education and communication spaces. Against this backdrop, and with a view to understanding how universities can create innovative pedagogical solutions to the rapidly changing communication and media ecosystems humans inhabit, we convened two online roundtable discussion, one with seven industry professionals and one with six higher-education academics and post-graduate students across Australia, New Zealand, the United States of America and Vietnam. We found that the teaching of non-vocational subjects, courses and material compliments Communication Studies degree programs with active listening, adaptability, and ethical research being key. These skills provide context for students who will be the communication professionals of tomorrow with an understanding of the diverse world they inhabit. Moreover, this project found that curiosity which is encouraged through humanities, arts and social sciences provides students with an appreciation of lifelong learning, as our societies face challenges due to rapidly evolving communication technological ecosystems leading to social and cultural change.</p
Acoustic modelling of textile fibre reinforced mortars and their sound absorption performance
No full textThis study focuses on the acoustic behaviour of fibre-reinforced mortars incorporating polyester, nylon, cotton, and elastane fibres. Micro-computed tomography was employed to estimate key acoustic pore characteristics, including open porosity, flow resistivity, and tortuosity. These parameters served as initial inputs for inverse estimation using the Johnson-Champoux-Allard acoustic model. The model's accuracy was validated through impedance tube measurements of the sound absorption coefficient and surface acoustic impedance. The model demonstrated strong predictive accuracy, with an average root mean square error of 0.0025 ± 0.0012 within the 500–1500 Hz frequency range, corresponding to the typical range of traffic noise. This suggests that the model can be effectively used to predict the sound absorption of textile fibre-reinforced mortars for traffic noise mitigation applications, eliminating the need for laboratory testing. Sensitivity analysis showed that open porosity and flow resistivity have a significant influence on acoustic performance, while tortuosity has a moderate impact. Good agreement was observed between micro-computed tomography-derived porosity and inverse-estimated porosity for all fibre-reinforced mortars. However, the limited resolution of micro-computed tomography, along with assumptions of the Johnson-Champoux-Allard model, such as homogeneous and isotropic pore geometry led to discrepancies in the predicted flow resistivity and tortuosity of specific mortars. Correlation analysis of micro-computed tomography derived pore characteristics with the average sound absorption revealed a strong relationship between open porosity and the sound absorption average. Based on this, a linear regression model was proposed to predict the sound absorption average using open porosity values. This work represents one of the first comprehensive studies to acoustically model textile fibre-reinforced mortars by combining microstructural analysis with theoretical predictions, supporting the development of sustainable, sound-absorbing cementitious materials.</p