University of Wollongong
  • Wollongong, NSW, Australia
Recent publications
Cosmogenic nuclide techniques have advanced the geosciences by providing tools for exposure age dating, burial dating, quantification of denudation rates and more. Advances in geochemistry, accelerator mass spectrometry and atom trap trace analyses are ushering in a new cosmogenic nuclide era, by improving the sensitivity of measurements to ultra-trace levels that now allow new applications of these techniques to numerous Earth surface processes. The advances in cosmogenic nuclide techniques have equipped the next generation of geoscientists with invaluable tools for understanding the planet, but addressing pressing needs requires rising to an even greater challenge: imbuing within the cosmogenic community, and the geosciences as a whole, a commitment to justice, equity, diversity and inclusion that matches our dedication to scientific research. In this Primer, we review the state of the art and recent exciting breakthroughs in the use of cosmogenic nuclide techniques, focusing on erosion factories over space and time, and new perspectives on ice sheet stability. We also highlight promising ways forward in enhancing inclusion in the field, as well as obstacles that remain to be overcome. Cosmogenic nuclide dating techniques provide tools for age dating, burial dating and denudation rates. Advances in accelerator mass spectrometry and atom trap trace analyses are improving measurement sensitivity. In this Primer, Schaefer et al. outline how to use cosmogenic nuclide dating across a range of applications.
Three-dimensional (3D) topological semimetals (TSMs) are a new class of Dirac materials that can be viewed as 3D graphene and are referred to as Dirac semimetals (DSMs) or Weyl semimetals (WSMs) depending on whether time reversal symmetry and/or inversion symmetry are protected, respectively. Despite some interesting results on Dirac- to Weyl-semimetal phase transitions under conditions of low temperature or strong magnetic field (B), all of them are reversible phenomena. Here, we report for the first time a possible permanent transition in a single TSM by ion implantation. A Dirac- to Weyl-semimetal phase transition in a Bi0.96Sb0.04 DSM results from inversion-symmetry breaking induced by implantation with nonmagnetic Au ions for implant fluences (ϕG) ≥ 3.2 × 10¹⁶ Au cm⁻². This phenomenon is evidenced by the ϕG-dependent behavior of the Raman spectra and quantum-oscillation parameters extracted from magnetoresistance (MR) measurements, which show abrupt changes at ϕG ≥ 3.2 × 10¹⁶ Au cm⁻². The verification of the transition is further supported by observations of negative MR in the longitudinal B // electric field orientation, indicating the existence of a chiral anomaly in Weyl fermions induced by implantation with nonmagnetic Au ions. In contrast, implantation with magnetic Mn ions exhibits no such particular behavior. Our findings demonstrate the first realization of a possible permanent DSM-to-WSM phase transition in a single material by the simple approach of implantation using nonmagnetic elements.
Background: This study aimed to investigate the longitudinal changes in emergency department (ED) presentations incurred by patients with alcohol use disorders. Methods: A retrospective quantitative analysis was conducted on patients' ED presentations between December 2011 and January 2019 in an Australian regional health district. The health district has five EDs serving rural, regional, and metropolitan areas. Patients with alcohol use disorders were divided into two groups for comparison: those who had interactions with the community-based Drug and Alcohol (D&A) services and those who did not. Results: A total of 2,519 individual patients with alcohol use disorders made 21,715 ED presentations. Among these patients, 75.4% did not have interactions with the community-based D&A services. Compared with those who had, these patients were older, more likely to be diagnosed with abdominal pain (26.9% vs 12.0%, p < 0.001) and chest pain (16.2% vs 8.6%, p < 0.001), and had longer mean length of ED stay (7 hours and 41.7 minutes vs 6 hours and 25.6 minutes, p < 0.001). For the patients who had interactions with the community-based D&A services, their 28-day re-presentation rates decreased from 55.5% (2013-14) to 45.1% (2017-18); however, were higher than that of those who had no interactions (41.1% to 32.8%). Overall, 21.9%-24.5% of the patients were frequent ED presenters (i.e., ≥4 visits per year). Frequent ED presenters were proportionately higher among the patients who had interactions with the community-based D&A services, consistently over the relevant years. Although patients with alcohol use disorders frequently presented to EDs, their alcohol use disorders were only identified in 8.9% of their presentations. Conclusions: Patients with alcohol use disorders were often unidentified in EDs. Those who did not have interactions with the community-based D&A services were less likely to be diagnosed with alcohol use disorders when presenting to EDs.
The battery management system (BMS) is the main safeguard of a battery system for electric propulsion and machine electrification. It is tasked to ensure reliable and safe operation of battery cells connected to provide high currents at high voltage levels. In addition to effectively monitoring all the electrical parameters of a battery pack system, such as the voltage, current, and temperature, the BMS is also used to improve the battery performance with proper safety measures within the system. With growing acceptance of lithium-ion batteries, major industry sectors such as the automotive, renewable energy, manufacturing, construction, and even some in the mining industry have brought forward the mass transition from fossil fuel dependency to electric powered machinery and redefined the world of energy storage. Hence, the functional safety considerations, which are those relating to automatic protection, in battery management for battery pack technologies are particularly important to ensure that the overall electrical system, regardless of whether it is for electric transportation or stationary energy storage, is in accordance with high standards of safety, reliability, and quality. If the system or product fails to meet functional and other safety requirements on account of faulty design or a sequence of failure events, then the environment, people, and property could be endangered. This paper analyzed the details of BMS for electric transportation and large-scale energy storage systems, particularly in areas concerned with hazardous environment. The analysis covers the aspect of functional safety that applies to BMS and is in accordance with the relevant industrial standards. A comprehensive evaluation of the components, architecture, risk reduction techniques, and failure mode analysis applicable to BMS operation was also presented. The article further provided recommendations on safety design and performance optimization in relation to the overall BMS integration.
Cutaneous squamous cell carcinoma (cSCC) is a disease with globally rising incidence and poor prognosis for patients with advanced or metastatic disease. Epithelial-mesenchymal transition (EMT) is a driver of metastasis in many carcinomas, and cSCC is no exception. We aimed to provide a systematic overview of the clinical and experimental evidence for EMT in cSCC, with critical appraisal of type and quality of the methodology used. We then used this information as rationale for potential drug targets against advanced and metastatic cSCC. All primary literature encompassing clinical and cell-based or xenograft experimental studies reporting on the role of EMT markers or related signalling pathways in the progression of cSCC were considered. A screen of 3443 search results yielded 86 eligible studies comprising 44 experimental studies, 22 clinical studies, and 20 studies integrating both. From the clinical studies a timeline illustrating the alteration of EMT markers and related signalling was evident based on clinical progression of the disease. The experimental studies reveal connections of EMT with a multitude of factors such as genetic disorders, cancer-associated fibroblasts, and matrix remodelling via matrix metalloproteinases and urokinase plasminogen activator. Additionally, EMT was found to be closely tied to environmental factors as well as to stemness in cSCC via NFκB and β-catenin. We conclude that the canonical EGFR, canonical TGF-βR, PI3K/AKT and NFκB signalling are the four signalling pillars that induce EMT in cSCC and could be valuable therapeutic targets. Despite the complexity, EMT markers and pathways are desirable biomarkers and drug targets for the treatment of advanced or metastatic cSCC. Graphical Abstract
Introduction We explored the footwear profiles and foot-related problems reported by netball players and whether these differed between males and females. Methods Two thousand nine hundred and twenty-five amateur, sub-elite and elite netball players (men n = 279; women n = 2646; age 26.4 ± 10.0 years) completed a custom-designed online survey with questions related to netball experience, current netball footwear habits and history of foot-related problems. Footwear profiles and foot-related problems were considered in logistic regressions against sex and competition level to ascertain significant relationships ( p < 0.05) and predictive values (odds ratio). Results Although 80.4% of respondents reported wearing netball-specific shoes, females were 13.2 times more likely to wear netball-specific shoes than males. Foot-related problems and foot pain were reported by 84.3% and 56.8% of netball players, respectively; with blisters, ankle sprain/strains and calluses being most common. Although women were significantly more likely to suffer from foot-related problems than men, males were significantly more likely to believe their foot pain was caused by the footwear they wore for netball. Conclusion The high prevalence of foot-related problems and pain reported by all netball players suggests that the shoes players are currently wearing for netball are not meeting the requirements of players, particularly regarding fit, comfort and functionality. As male netball players have significantly different footwear profiles to female players, men are likely to require netball-specific footwear that differs to the netball-specific shoes designed for female players.
Laser diodes (LDs) experiencing external optical feedback (OF) are known to demonstrate complex nonlinear dynamics and found various applications. Typical sensing configuration using an LD with OF is called optical feedback interferometry (OFI) that can produce an interferometric-like fringe signal (called OFI fringe) with a fringe resolution as half laser wavelength for displacement measurement. This work uses a dual-cavity OFI and operates the LD at Period-One (P1) state. By optimal configuration for such system, a microwave photonic (MWP) signal can be generated in oscillation form at a very high frequency with its amplitude modulated by an OFI fringe signal. The high frequency component contained in the MWP signal is used for subdivision of an OFI fringe to greatly improve sensing resolution. Both simulation and experiment are conducted to confirm the proposed approach for OFI fringe subdivision.
Three stages of nitrogen (N2) injection enhanced gas drainage through underground in-seam boreholes were carried out in a coal mine located in the southern Sydney basin. Due to the high CO2 content and low permeability, hard-to-drain coals were encountered during the excavation process in this coal mine. Two parallel in-seam boreholes (the length of 36 m, the diameter of 96 mm and the borehole space of 5 m) were drilled on the rib of the gateroad. A total of ten-cylinder packs of nitrogen (approximately 1500 m³) were injected into the coal seam. Different nitrogen injection pressures (150 KPa, 250 KPa, 350 KPa and 450 KPa) and injection methods (continuous injection and cyclic injection) were employed. Gas flow rates and gas compositions from the production borehole were recorded during and after the nitrogen injection process. It was observed that gas breakthrough was tightly related to the nitrogen injection pressure. The higher injection pressure was, the shorter breakthrough time was. Specifically, no gas breakthrough was obtained when the injection pressure was 150 KPa. The minimum of breakthrough time was 35 min when 450 KPa’s injection pressure was employed. Strong post-injection effect was monitored after each stage of injection and it was affected by the volume of the injected nitrogen. Under the current injection conditions, the performances of different injection methods were like each other, which was out of our expectation. After the injections, the results of cores showed that less than 5 % of the total injected nitrogen was remained in the coal seam. The coal seam gas content dropped 0.99–1.65 m³/t after these three stages of injection. All these findings provide implications and guidance not only for laboratory experiment and numerical modelling, but also for the field application of this new technology.
Due to the widespread proliferation of distributed generation resources and the current market situation, ensuring the security and reliability of power grids against fault events has become a more challenging task. The aim of this paper is to compare different power flow techniques for power grid vulnerability assessment against symmetrical fault incidents using bus impedance matrix. In this study, first, the relationship of the post-fault voltage phasor at each bus with the pre-fault voltage phasors at that bus and the faulted bus, impedance matrix elements, and fault impedance is investigated through power system analysis under pre-fault and post-fault circumstances. Subsequently, the accuracy of different iterative and non-iterative power flow algorithms, i.e. Newton Raphson (NR), Fast Decoupled (FD), and Direct Current (DC) methods, for the power grid vulnerability assessment is compared. To achieve this, the fault analysis at each bus is performed commencing with a very large fault impedance and ending with the fault impedance at which one of the buses reaches the low voltage violation limit. Finally, to appraise the proposed strategy, several simulations have been undertaken on IEEE 14 bus system using MATLAB software. The simulation results indicate that the power grid vulnerability against symmetrical faults is highly influenced by the type of applied power flow technique.
Redox flow deionization (RFD) is an emerging derivative of redox flow cell technology that desalinizes salt water while simultaneously storing energy. However, conventional RFDs are limited by high specific energy consumption and low salt removal rates caused by low ionic conductivity in low-salinity ranges (especially < 3000 mg L–1). This study investigates the potential of ion transport channels composed of ion exchangers to enhance ionic conductivity in low-salinity ranges. The RFD cell with ion exchangers (IE-RFD) exhibited significantly lower resistance and specific energy consumption than conventional RFD cells when processing low salinity feeds. A finite element analysis demonstrated that the current density in the ion exchangers, especially where the ion exchangers were in contact, was much higher than that of the surrounding solution, indicating effective ion transport in low-salinity ranges. The IE-RFD cell showed excellent desalination performance (99.4% at 10 000 mg L–1) and low energy consumption (0.99 Wh L–1). We did not observe any deterioration in performance over 10 d of continuous desalination. Compared with other electrochemical desalination technologies, e.g., membrane capacitive deionization, flow capacitive deionization, and traditional RFD, the IE-RFD is superior in terms of energy consumption, salt removal ability, and stability. This study described an efficient strategy to enhance the desalination performance of RFDs through ion transport channels. With further optimization, this technology could help to alleviate the critical global demand for fresh water using minimal energy.
This paper addresses digital transformation in higher education by exploring the engagement and use of e-textbooks through an affordance theory lens. Drawing on the insights from in-depth interviews (n = 18), focus group discussions (n = 15), a pilot survey (n = 83) and the main survey (n = 344) in Australia, we developed and validated an affordance actualisation model for the engagement and use of e-textbooks. The partial least squares (PLS) technique was used to validate the dimensions of affordance actualisation and its relationship with e-textbooks engagement and affordance effect. The findings indicate the efficacy of the two affordance constructs, as well as the significant mediating effect of engagement. An important lesson for the e-textbook industry is that firms need to consider affordance actualisation dimensions (i.e., portability, accessibility, searchability, highlighting, copying, browsing, hedonic and utilitarian value) when enhancing digital engagement and use of e-textbooks.
The vision of “lead-free” instead of “lead” is growing as people pay more attention to environmental problems, especially since performance improvement of lead-free piezoelectric materials is imminent. The introduction of local heterogeneity, relaxor behavior, and nanodomain engineering based on heterovalent-ions has been proved to be highly effective for further increasing of performance of piezoelectric materials. However, how the doping level will work towards improving the piezoelectric performance, especially the lead-free piezoelectrics is an open question. In this work, we have assembled (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramics based on the traditional phase-structure construction strategy and used microscale heterovalent-ion Al element doping to regulate its piezoelectric properties. The optimization of piezoelectric properties, on the one hand, comes from large lattice distortion caused by appropriate Al doping, leading to high asymmetry and enhancement of the displacement of B−site ions. On the other hand, the behavior of a ceramic with a low defect concentration and an N-type conductivity mechanism is guided by its defect chemistry. The defect configuration analysis explains in detail the process of Al³⁺ ions entering A-sites and B-sites in turn with change in the doping concentration, that is, from donor doping to acceptor doping, and the influence of the change in defect concentration caused by this process on piezoelectric properties. When the doping level of Al³⁺ ions is 0.25 mol%, it is exciting to find that the piezoelectric performance is significantly high (piezoelectric coefficient d33 = 638 pC/N, electromechanical coupling factor kp = 54%). The interpretation of heterovalent-ion doping in this work is different from the strategy for traditional high-performance piezoelectric materials. This discovery facilitates a new mechanism of doping for improving piezoelectricity, which will help to further improve the piezoelectric performance of different piezoelectric materials.
One of the major goals of mining science is to develop models that connect monitoring signals with the dynamics accompanying hazards. Whether the triggering process of an outburst produces observable signatures is a fundamental question related to the potential for outburst early warning realization and probabilistic forecasting. Inspired by a recent discovery that certain volcanoes often generate infrasound waves before eruption, we hypothesize that a similar infrasound-generating mechanism occurs in select outburst-triggering processes. In the laboratory, we designed an experimental program to verify our hypothesis, which considered the presence of a gas pocket at the trigger stage. The results indicated that periodic infrasonic tremors spontaneously emerge if gas temporarily accumulates in the gas pocket before escaping from the simulated coal seam. Moreover, the tremor frequency systematically decreases with increasing pocket thickness. Therefore, we proposed a viable model to explain the origin of these periodic tremors. In particular, our model demonstrated that the pressure in the gas pocket is governed by the equation of a linear oscillator. Hence, under proper conditions, infrasonic tremors emerge due to periodic pressure oscillations in the gas pocket. More importantly, our model predicted that different outburst-triggering processes (e.g., fracture development and excavation) can leave distinct footprints in the tremor properties. If this model holds true for actual coal seams, it could be possible to predict outbursts. Our tremor model also opens new perspectives for dynamics monitoring within coal seams.
Cyberbullying behavior (CB) on social media is complex because its perpetrators exhibit varied demographic characteristics and personalities. Prior studies have applied Big Five (Big5) and Dark Tetrads (Dark4) personality traits (PTs) along with demographic attributes, using symmetrical modelling, but revealed mixed and inconsistent results. This paper applies an asymmetric modelling approach using complexity and configurational theories to develop configurations of PTs and demography to predict CB. The online survey data have been analyzed using fuzzy set qualitative comparative analysis (fsQCA) technique. Regarding Big5 PTs, our findings reveal that, for instance, people scoring high in conscientiousness, neuroticism, openness and low in agreeableness undertake cyberbullying. For Dark4 PTs, the combination of either psychopathy and sadism or Machiavellianism and psychopathy leads to cyberbullying. As for demographic attributers, educated young married people, irrespective of gender, are likely to commit cyberbullying. Our all-inclusive model reveals that social media bullies, regardless of their gender, marital status, and social media experience, are young, educated, neurotic, conscientious, psychopathic, and sadistic with high Machiavellianism and low agreeableness. Further, we suggest configurations to reduce cyberbullying. The findings are discussed with implications for theory and practice.
Developing solar-powered electric bus networks in high-density cities can greatly mitigate their increasing energy and environmental challenges such as carbon emission, street-level air pollution, and renewable penetration to the power grid. However, such solar-powered electric bus networks face a charging control issue that is caused by the severe and frequent mismatch between PV power generation and bus charging demand. Without proper consideration of this mismatch, renewable energy generation cannot be effectively utilized, and heavy grid dependence (i.e., energy exports/imports to/from power grids as solar power surplus/insufficient) will still exist. Meanwhile, the electric bus network charging issue is a complex constraint-based and high-dimensional control problem that requires holistically coordinating charging operations of a large number of electric buses (i.e., when and at which terminus to charge) while satisfying various constraints (e.g., bus schedule, bus battery capacity and charging power limits, limited charging stations in a terminus). Existing charging control methods of solar-powered electric vehicles may not be applicable for this problem. To address this knowledge gap, this study proposed a mixed-integer-linear-programming-based control strategy for solar-powered electric bus networks with improved renewable energy on-site consumption and reduced grid dependence. A case study of a bus network with reference to 10 real bus terminuses in Hong Kong was used to validate the performance of the proposed control in comparison to a rule-based one (i.e., first-come-first-served [FCFS]). The results showed that the proposed control can significantly improve the renewable energy on-site consumption ratio from 0.457 to 0.813, while the grid dependence indicator was reduced from 0.809 to 0.451. The in-depth analysis showed that the proposed control can realize both temporal and spatial demand shifting which mainly contributes to the performance improvements. The results also revealed to achieve the same performance of the proposed control, the FCFS control requires installing a large-sized battery storage system, i.e., 45-MWh. The proposed control can be used to facilitate the development of solar-powered electric bus networks in high-density cities, thereby alleviating associated carbon emissions and air pollution.
A hybrid solar photovoltaic-thermal collector is the combination of a solar thermal unit and a photovoltaic panel for the simultaneous generation of heat and electricity. In these systems, a fluid is used to cool photovoltaic panels and, thus, prevent their reduction of electrical efficiency. The hot fluid leaving the system can also be used in various kinds of engineering applications, from agriculture to heating, ventilation and air conditioning units, and process heat in utilities. Coolants used in photovoltaic-thermal units include air, water and nanofluids, among which air is less efficient than water and nanofluids due to its low specific heat capacity. Although extensive research has been done on the exergy performance of photovoltaic-thermal units, the number of published review articles in this field is very limited. This paper presents a critical review with some recommendations for future research on the topic of exergy examination of water-based and nanofluid-based photovoltaic-thermal units. As a first step, the concept and mathematical exergy relations are introduced. Then, water-based and nanofluid-based photovoltaic-thermal units are exergetically discussed in detail, followed by the description of novel units. At the end of each section, some suggestions are presented for future exergy examination of those types of photovoltaic-thermal units.
The potential of microalgae in wastewater treatment and resource utilization has received considerable interest. For better outcomes in large-scale cultivations, it is usually essential to optimize the microalgal culture parameters in a sub-pilot cultivation system. Herein, a series of experiments were carried out to investigate the effects of photoperiod, CO2 concentration and aeration intensity on nutrients removal and biomass production of Tetradesmus dimorphus under the 50 L culture scale. The results showed that the removal rates of chemical oxygen demand (CODcr), NH4⁺-N and total phosphorus (TP) in primary effluent (PE) were 93.9 %, 92.3 % and 84.8 %, respectively. Compared with 15 h:9 h (15 h light and 9 h dark cycle), the maximum Chlorophyll-a content of 2797.78 mg/m³ was reached at 24 h:0 h. The maximum microalgae biomass (OD680 = 0.56) was obtained when the CO2 concentration was 200 mL/min, but CO2 enrichment inhibited nitrogen removal. At optimal aeration intensity (60 L/h), the highest chlorophyll-a content was recorded on day 3. The removal rates of NH4⁺-N and TP were 92.1 % and 89.7 %, respectively.
CMT-Wire Arc Additive Manufacturing (CMT-WAAM) has the advantages of low heat input and high production efficiency. However, the surface geometric accuracy of the CMT- fabricated sample is inferior, especially for the deposition of titanium alloy. The focus of this study was to analyze the metal transfer behavior during CMT-WAAM of titanium alloys by a high-speed camera. The metal transfer and molten pool behaviors during the single-layer and multi-layer deposition in both CMT and CMT + P modes were compared to optimize the characteristic process parameters. The results showed that the hybrid metal transfer mode, including the short-circuit transition and the globular transition, occurred in the CMT + P mode. The effect of Ip1 on the droplet diameter was more significant than that of tp1. Under these two modes, the size and spread ability of the molten pool increased with the increase of Iboost, tp1 and Ip1. While in the CMT + P mode, Ip1 did not yield a significant influence compared with tp1. Simultaneously, noticeable oxide skin was observed on the surface of the flowing molten pool when Iboost reached 350 A in the CMT mode. Compared with the CMT mode, new spatter types were generated by arc force and droplet free-fall motion in the CMT + P mode. Ultimately, the maximum effective rate of 70.4 % was obtained in the CMT + P mode when the parameters were selected as Ip1 = 400 A and tp1 = 4 ms.
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12,390 members
Mark Dowton
  • School of Biological Sciences
Mitchell Byrne
  • School of Psychology
Madeleine Du Toit
  • School of Mechanical, Materials & Mechatronic Engineering
Paul Goldberg
  • School of Earth, Atmospheric and Life Sciencess
Jackie Street
  • School of Health and Society
1 Northfields Avenue, 2522, Wollongong, NSW, Australia
Head of institution
Professor Paul Wellings