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Numerical Study of Thermal Conduction and Convection Using Lattice Boltzmann and Finite Difference Methods
No full textThis paper presents a 2D numerical analysis of thermal conduction and convection phenomena using a hybrid Lattice Boltzmann-Finite Difference (LB-FD) model. The study focuses on the simulation of conjugate heat transfer in a cavity filled with air. This cavity is characterized by two cold vertical walls and a relatively thick bottom part, considered solid and heated from below. The study aims to examine the impact of the choice of solid material on the heat exchange process. Analysis of the findings indicates that increasing the value of the thermal conductivity of the material increases the rate of heat transfer inside the cavity. For example, for a Rayleigh number set at 106, the results show that heat exchange increases by 156.97% when the solid/air thermal conductivity ratio is increased from 1 to 800. The study suggests that the LB-FD approach is an appropriate method to simulate thermal conduction and convection phenomena and can be employed to study more complex thermal problems with conjugate heat transfer. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024
Potential financial loss and risk factors for hamstring muscle injuries in elite male Brazilian soccer players : a season-long prospective cohort pilot study
Get PDFPurpose: The aim of this pilot study was to analyze the potential financial loss and a range of potential risk factors for hamstring muscle injuries in elite Brazilian soccer. Methods: Thirty-four male players (age: 25 ± 6 years; stature: 180 ± 8 cm; body mass: 78 ± 9 kg; minutes played in matches: 2243 ± 1423 min) from an elite professional soccer club were monitored during a 12-month season. Muscle injury was identified by magnetic resonance imaging and the severity was defined according to the number of days away: minimal (1–3 days), mild (4–7 days), moderate (8–28 days), severe (>28 days). Potential financial loss due to the team's under achievements was determined. Dorsiflexion range of motion, eccentric knee flexor strength and isokinetic tests were performed during the pre-season. Association between dependent variables and the occurrence of injury was evaluated. Results: Nine hamstring muscle injuries with moderate severity were found in 8 athletes. Recovery time was 22 days off the field on average. Potential financial loss was $-43.2 million USD and earnings on merit money was 21%. Previous injury, increased flexor deficit 60° /sec and increased flexor fatigue index 300°/sec were all associated with a greater chance of hamstring muscle injury. Ankle dorsiflexion range of motion was significantly lower in the injured group (35.6 ± 3° vs. 39.1 ± 4.9°; p = 0.017, effect size
Experimental and numerical investigations on the ultimate flexural strength of concrete beams reinforced with grade 750 steel bars
Get PDFHigh strength steel bars have recently been added to design code provisions for reinforced concrete structures. However, there is a gap in the current knowledge on the flexural strength of beams reinforced with ultra-high strength steel, with nominal yield strength exceeding 690 MPa. Grade 750 ultra-high strength steel bars offer a 50 % increase in yield strength over traditional grade 500 bars alongside other benefits such as reduced mass, diminished reinforcement congestion and lower carbon emissions. To address this knowledge gap and evaluate the applicability of current design codes, a series of experimental tests were conducted on concrete beams longitudinally reinforced with commercially manufactured grade 750 steel. Equivalent beam designs employing grade 500 steel bars were tested for comparative analysis. The outcomes of these experiments revealed that current standard guidelines tend to provide conservative predictions for the moment capacity of beams reinforced with grade 750 steel. For further investigations on the ultimate flexural capacity of concrete beams reinforced with ultra-high strength steel, a finite element model was developed and validated against the experimental results. This model incorporated combined damage plasticity for concrete, nonlinear damage for steel and a three-dimensional bond-slip mechanism capturing the steel-concrete interface. Furthermore, a detailed analytical method was presented based on the constitutive behaviour of grade 750 steel. The strength predictions generated by this model were compared to results obtained from experiments and finite element simulations. This model demonstrated increased accuracy in predicting the ultimate flexural strength of beams reinforced with grade 750 steel bars to 92 %. © 2024 The Author
Isolation and characterization of enterococci from poultry reveals high incidence of Enterococcus thailandicus in Victoria, Australia
Get PDFAims: Antibiotic resistance is a global health crisis. Roughly two-thirds of all antibiotics used are in production animals, which have the potential to impact the development of antibiotic resistance in bacterial pathogens of humans. There is little visibility on the extent of antibiotic resistance in the Australian food chain. This study sought to establish the incidence of antibiotic resistance among enterococci from poultry in Victoria. Methods and results: In 2016, poultry from a Victorian processing facility were swabbed immediately post-slaughter and cultured for Enterococcus species. All isolates recovered were speciated and tested for antibiotic susceptibility to 12 antibiotics following the Clinical Laboratory Standards Institute guidelines. A total of 6 farms and 207 birds were sampled and from these 285 isolates of Enterococcus were recovered. Eight different enterococcal species were identified as follows: E. faecalis (n = 122; 43%), E. faecium (n = 92; 32%), E. durans (n = 35; 12%), E. thailandicus (n = 23; 8%), E. hirae (n = 10; 3%), and a single each of E. avium, E. gallinarum, and E. mundtii. Reduced susceptibility to older classes of antibiotics was common, in particular: erythromycin (73%), rifampin (49%), nitrofurantoin (40%), and ciprofloxacin (39%). Two vancomycin-intermediate isolates were recovered, but no resistance was detected to either linezolid or gentamicin. Conclusions: The relatively high numbers of a recently described species, E. thailandicus, suggest this species might be well adapted to colonize poultry. The incidence of antibiotic resistance is lower in isolates from poultry than in human medicine in Australia. These results suggest that poultry may serve as a reservoir for older antibiotic resistance genes but is not driving the emergence of antimicrobial resistance in human bacterial pathogens. This is supported by the absence of resistance to linezolid and gentamicin. Impact Statement Antimicrobial use in Australian poultry rearing does not drive resistance to antibiotics critical in human medicine; Enterococcus thailandicus is prevalent in Australian poultry. © The Author(s) 2024
Building the status of teaching-focused positions as prestigious roles to improve teaching quality
Get PDFTeaching-focused roles provide an ideal opportunity to improve the quality of teaching in higher education. However, such roles are commonly presented as pragmatic solutions for academics not fulfilling research expectations rather than quality improvement interventions. Workload allocations can be shifted to ensure that unproductive researchers are not counted as research-active in university ranking assessments and, at the same time, help balance salary budgets. These measures to address underperforming researchers have shifted focus from the potential to improve teaching quality that teaching-focused roles promised. We argue that a successful implementation of a supported approach for teaching-focused academics can help to foster a culture of excellence in teaching that should deliver career development and associated benefits for those in teaching-focused roles. This paper discusses a considered approach to improving teaching in higher education by supporting teaching-focused roles in an Australian university. Strategies to raise the profile of teaching-focused academics included a high-level champion, a merit-based application process, and a development program. These strategies aimed to address mis-focused perceptions and stigma related to teaching-focused positions and contribute to a culture of excellence in teaching. We put this approach forward as a model for institutions wanting to improve teaching quality, implement or enhance teaching-focused career paths or review existing models
Closing the employment gap : estimations of Indigenous employment in Indigenous- and non-Indigenous-owned businesses in Australia
Get PDFIndigenous-owned businesses in Australia are strong employers of Indigenous people, maintaining rates of Indigenous employment that are not seen across the breadth of the Australian economy. Despite an increasing focus from governments and private organisations to improve rates of Indigenous employment, there is limited evidence to suggest that substantial improvements are being made. Despite acknowledgement from government of the crucial role played by Indigenous employers in creating Indigenous employment, there has been little focus on what may be learned from the Indigenous business sector in informing public and private Indigenous workplace and recruitment policies. Given the significantly strong levels of Indigenous employment in Indigenous-owned businesses, it is important to interrogate the extent to which this employment differs from that in non-Indigenous businesses and the potential explanations for such divergence. Using data from Supply Nation (2,291 Indigenous-owned businesses) and a survey of 680 non-Indigenous businesses, this paper finds that Indigenous businesses employ Indigenous people at a rate 12 times higher than non-Indigenous businesses. Regression analyses and Oaxaca-Blinder decompositions reveal that these divergent employment outcomes cannot be explained by the broad characteristics of the two sectors (such as industry, location, or profit status). These findings help confirm that the unique workplace practices of Indigenous businesses may explain their strong Indigenous employment and, therefore, provide the template for all Australian businesses to be better employers of Indigenous people. © The Author(s), 2024. Published by Cambridge University Press on behalf of The University of New South Wales
Self-efficacy, grit, and rural career aspirations among early career nurses: a repeated cross-sectional study
Get PDFBackground: Global nursing workforce shortage represents an impediment to the delivery of safe, evidence-based healthcare. Despite collective efforts, a consistent stream of nurses leaving the profession remains, particularly within the first five years of practice, which is exacerbated in rural communities. The aim of the study was to compare self-efficacy, grit, and rural career aspirations among nursing graduates between their second and fourth year of their nursing profession. Methods: As part of a longitudinal investigation, a repeated cross-sectional design was utilised. Participants included, 117 (response rate 52.2%) who completed an online questionnaire 18–24 months after graduating, and 32 participants (response rate of 21.0%) who agree to repeat the questionnaire 36–48 months after graduating. The questionnaire included demographic, employment, and measures examining general and occupational self-efficacy, grit, and rural career aspirations. Results: No differences between general and occupational self-efficacy or grit were identified between second- and fourth-year nurses. In addition, the importance placed on undertaking rural career also remains unchanged. However, a higher proportion of fourth year nurses were more likely to be in management or were considering leaving the profession. Conclusions: This examination of early career nurses, now in their second and fourth-year post-graduation highlights self-efficacy, grit, and rural career aspirations remains stable between two- and four-years following graduation, while nursing in their fourth year were more likely to consider leaving the profession. Nursing retention is a ‘Wicked Problem’ that is unavoidably a complex amalgam of macro, meso and micro factors that we are yet to fully appreciate. © 2024, The Author(s)
A review of electronic devices for tracking small and medium migratory shorebirds
Get PDFSmall- to medium-sized shorebirds (< 200 g) can be particularly difficult to track with electronic devices due to their small size and long-distance migrations which place restrictions on device weight and size. A lack of comparative information on suitable tracking devices makes selecting the most appropriate technology time consuming and complex and can result in duplication of effort for each research project. The purpose of this paper is to address this issue by presenting a review of the scientific literature and commercially available devices to help inform device selection as well as options for attachment. The ideal device for tracking small to medium migratory shorebirds would be light weight (< 5% of a bird bodyweight), flat in profile, durable, have high battery longevity, remote data download, easy to attach from a bird welfare perspective, high spatiotemporal resolution and would be low in cost (so that a large enough sample size can be obtained). This ideal device does not yet exist due to the limitations on the weight of the power supply necessary to obtain frequent, high resolution location fixes over long time periods. As a result, the current choice of device depends on the purpose of the study. Platform Transmitter Terminal (PTT) doppler devices are suitable for tracking long distance movement due to their smaller size and lighter weight (around 2 g), but produce lower resolution location data and are expensive. For tracking smaller-scale movements (i.e., tens of kilometres), Global Positioning System (GPS) devices are more suitable, because they produce higher-resolution location data and are often more cost effective but tend to be heavier. Other device options for obtaining movement data include radio telemetry and light-level geolocators, which are generally lighter and cheaper than GPS or Doppler devices but require more effort to retrieve data and often produce lower resolution location data. Attachment methods and materials vary, but the most suitable is usually leg loop harnesses made with soft materials that are likely to degrade (e.g., elastic). Device type and harness design need to be carefully chosen to minimize potential impacts on the animal. © The Author(s) 2024
Optimizing process parameters and materials for the conversion of plastic waste into hydrogen
Get PDFThis study has investigated hydrogen production from waste plastics using pyrolysis, steam methane reforming, and water-gas-shift reactions modelled via Aspen Plus. After evaluating multiple alternatives, polypropylene (PP) was selected as the feedstock. The research has been focused on how reformer temperature, steam-to-fuel ratio (S/F), reformer pressure, and pyrolysis temperature impact syngas composition, heating values, syngas (H2/CO) ratios, and yields of hydrogen (H2), methane (CH4), and carbon dioxide (CO2). Key findings have indicated that raising reformer temperatures to around 1000°C maximizes hydrogen production in syngas, reaching peak levels of 2360 Nm3/Ton and 2525 Nm3/Ton for reformer temperature and steam-to-fuel ratio (S/F) ratios, respectively, via processes like steam methane reforming and the water-gas-shift reaction. Moreover, other parameters like steam-to-fuel (S/F) ratio and reformer pressure have produced the highest amount of hydrogen at 0.25 and 1 atm, respectively. Optimizing reformer temperature and steam-to-fuel ratio (S/F) have been selected as key in hydrogen production, with peak lower heating values (LHV) of 1.15 MJ/kg for temperature and 1.035 MJ/kg for S/F ratios, highlighting the importance of balancing these parameters for efficiency. Additionally, syngas' hydrogen (H2) composition increased with pyrolysis temperature, peaking at 8.5% at 700°C. Finally, this research has provided valuable insights into optimizing process parameters for sustainable hydrogen production. Moreover, the simulation process has provided cost-effective adjustments and informed decision-making for sustainable and scalable technologies, benefiting researchers, investors, engineers, and policymakers involved in innovative hydrogen generation. © 2024 The Author(s). Published by IOP Publishing Ltd