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3D modelling of the hydraulic performance of open-graded asphalt using the DEM and CFD methods
No full textIn this study, we propose a modelling approach that combines computational fluid dynamics (CFD) and the discrete element method (DEM) to simulate the hydraulic performance of three-dimensional (3D) porous asphalt (PA) specimens. Initially, realistic aggregate appearances are captured through the image analysis technique. This information is then transferred to DEM software for the reconstruction of pore structure with distinct aggregate shapes following the real particle size distribution (PSD) as identified by local construction standards. The pore structure, reproduced via DEM, is used as input for CFD simulation to assess the hydraulic performance. To capture the dynamic of water motion simulation, the multiphase model, volume of fluid method (VOF), within CFD is applied to track and predict the interactions between different material phases, and the effect of porous structure to the hydraulic behaviour and performance. Results of numerical simulations indicate that PA samples with higher total porosity (air voids) have better pore connectivity and more effective porosity. For samples with the total porosity of 20%, the difference between the total porosity and the effective porosity was 14.8%; while a much lower difference of 8.3% was found for the higher porosity (25%) specimen. Compared with effective porosity, the reduction in active porosity reaches 58.8% in deeper layers for the sample at 20% total porosity, and only 32.2% for the sample at 25% total porosity. Overall, the results show that there is about a 4.57 times difference in hydraulic performance represented by mass flow rate among PA samples with 5% total porosity difference
Musculoskeletal Injury in Australian Professional Musical Theatre Shows: A 5-Year Retrospective Observation Study of 2,249 Medical Attention Injuries
No full textOBJECTIVE: To investigate the frequency and trends of musculoskeletal medical attention injuries occurring in Australian professional musical theatre performers over two consecutive Australian city tours. METHODS: Medical attention performance-related injuries were prospectively reported from 269 professional Australian music theatre performers across nine professional music theatre productions from 2015 to 2020. Medical attention injuries were defined as a presentation to physiotherapy for assessment or treatment of a body region that may or may not have resulted in time lost on stage. RESULTS: 844 injuries were reported in City 1 and 776 injuries were reported in the City 2. The proportion of performers reporting injuries in City 1 ranged from 39.5% to 96.4% and in City 2, from 15.4% to 92.9%. Cervical spine injuries (ncity1 = 194, ncity2 = 187) were the most prevalent musculoskeletal presentation to physiotherapy followed by lumbar spine (ncity1 = 124, ncity2 = 117) and thoracic spine (ncity1 = 124, ncity2 = 90). There were more acute injuries reported in City 1 than City 2 (adj residuals = –4.09, p < 0.001) and more persistent injuries in City 2 (adj residuals = 4.09, p < 0.001). CONCLUSION: Almost half of all injuries requiring medical attention in Australian professional music theatre performers were related to the cervical, thoracic and lumbar spine, with an increasing trend of cervical spine injury frequency across show durations. The study suggests a need for targeted injury prevention strategies in this population
Linking demographic and habitat suitability modelling identifies the environmental determinants of successfully controlling invasive common carp (Cyprinus carpio) in south-eastern Australia
No full textCommon carp (Cyprinus carpio) are a serious invasive species of riverine habitats in Australia and several control measures have been proposed. The strategy and potential success of any control measure will be influenced by carp population dynamics. Carp survival and distribution are driven by abiotic environmental factors (e.g., water flow rates and habitat availability), which vary greatly in space and time in Australian river systems. To inform realistic control strategies, we developed a mechanistic (process-based) carp metapopulation model with parameters explicitly linked to spatio-temporal estimates of habitat suitability. To demonstrate the use of this model, we evaluated how recovery times following a one-time management action (that results in population reduction) varied across five river catchments in the Murray-Darling Basin (MDB), eastern Australia, using reconstructed environmental conditions from the early 1990s to 2016. We found that recovery time at the catchment scale can be highly dependent on the flood-drought cycle, with recovery varying from to 2 to 10 years between wet and dry periods. In more stable catchments, however, ~ 6 years (range 4–8 years) is more likely. Our results are consistent with the paradigm that carp are a highly successful invasive species, with strong recovery potential, especially during periods of access to quality nursery habitat (i.e., during floodplain and wetland inundation)
Blood Homocysteine Levels Mediate the Association Between Blood Lead Levels and Cardiovascular Mortality
No full textLead is a heavy, toxic metal and its exposure to humans can lead to increased risk of cardiovascular disease development and mortality. Lead exposure has been shown to induce hyperhomocysteinemia (HHCy) which may be a major pathogenic risk for the risk of CVDs. The aim of this study was to investigate whether homocysteine (Hcy) mediates the effect of lead on cardiovascular mortality. A total of 17,915 adults aged ≥ 20 who participated in the National Health and Nutrition Examination Survey (1999 to 2006). Information on mortality was ascertained via probabilistic matching to the death certificates from the National Death Index recorded up to December 31, 2015. Cox proportional hazards regression was performed to assess the association between blood lead levels and mortality. Mediation via Hcy was examined using a logit model. During a mean follow-up of 11.6 years, the incidences of CVD mortality were 0.73, 2.18, 3.03 and 4.94 per 1000 person-years across quarterlies of blood lead levels from low to high. Following multivariable adjustment, blood lead levels were strongly associated with CVD mortality in all mortality models (p-trend < 0.001). This association remained statistically significant after further adjusting for quartiles of homocysteine (model 3; HR 1.38 (95% CI 1.01—1.89) p-trend < 0.001). Furthermore, blood lead levels increased the odds of CVD mortality via homocysteine (indirect effect) (OR 1.42 (95% CI 1.30—1.55)), demonstrating the mediatory effect of homocysteine. This the first study that demonstrates that increased homocysteine mediates nearly half of CVD mortality related to blood lead levels
In-depth investigation of air quality and CO2 lock-up phenomenon in pilots’ local environment
No full textThe understanding of the cockpit environment with regard to air quality and contaminant suspension is currently very limited. With the escalating concerns of pilots’ health and flight performance being revealed with association to these two aspects, this study numerically investigated the air quality and CO2 lock-up phenomenon in pilots’ local environment based on the actual dimensions of widely used aircraft prototype—Boeing 737, using computational fluid dynamics (CFD) approach. Three ventilation layouts and configurations with real operational conditions were considered and their performance and effectiveness in diluting the contaminants (CO2) released from pilots’ mouths, were carefully assessed with the indoor air-related indices. The results revealed that only relying on the cockpit diffusers could hardly achieve a good air mixing from the pilots’ breathing level while activating the windshield inlets and personal gaspers could both be effective. Using the personal gaspers was found the most cost-effective way to facilitate the local air mixing in the breathing zone. The current three ventilation strategies were not optimal in minimising the CO2 concentration in pilots’ micro-environment. Significant CO2 lock-up phenomenon with concentrations from 700 to 1000 ppm can be noticed. When the design priority is to effectively minimise the local contaminant in pilots’ breathing zone, appropriately changing the location of the vents could be more effective than increasing the mass flow rate. With current ventilations, nearly 6%–15% of pilots would fail the pilot manoeuvring performance under the FAA Practical Test Standards and from a healthy perspective, several sick building syndromes can be initiated, such as nose/sinus irritation, sore throat, and wheeze
Multidisciplinary design and optimization of intelligent Distributed Satellite Systems for EARTH observation
No full textRecent advances in small, connected and intelligent satellite systems have created a wide range of opportunities for the adoption of intelligent Distributed Satellite Systems (iDSS) in communication, navigation and Earth Observation (EO) missions. iDSS are goal-oriented systems comprising of multiple satellites or modules that interact, communicate and/or cooperate with each other to accomplish the desired mission goals. The ability to mass-produce low-cost small satellites and contemporary developments in avionics/astrionics technology have spurred interest in iDSS, especially for Low Earth Orbit (LEO) satellite constellations and regional clusters. The SmartSat Cooperative Research Centre (CRC) and Australian space roadmap, as well as the landmark National Space Programme strategy and priorities, encompass EO. To date, insufficient progress and no conclusive outcome was made in terms of how contemporary Multidisciplinary Design Optimization (MDO) models and tools can be best tailored to the new capabilities and specificities of iDSS. The MDO of iDSS is challenging because it introduces new variables and highly non-linear interactions. In this context, we propose an MDO methodology to optimize an iDSS for persistent coverage over the entire Australian landmass. Several aspects of the iDSS are considered in this work, including the constellation model, subsystem models and the coupling interactions between different satellite subsystems and constellation design parameters. The constellation configuration, as well as the subsystems, are modelled using OpenMDAO, which is used to analyze and visualize the planned iDSS EO mission. The iDSS is then optimized using the Multidisciplinary Feasible (MDF) architecture approach and the iDSS interdependencies are numerically treated using the Nonlinear Block Gauss-Seidel (NLBGS) iterative solver. The resulting N2 diagrams are presented and the proposed solution is both spatially and temporally optimized, demonstrating that th
Risk assessment and management of rainfall‑induced landslides in tropical regions: a review
No full textExcessive rainfall is considered the major landslide triggering mechanism, especially in tropical climate regions. During rainfall, water infiltrates into the subsurface; reducing the matric suction, increasing pore water pressure, and decreasing the shear strength of the soil. The prevailing unfavourable ground and geomorphological conditions can further exacerbate the vulnerability and severity of catastrophic landslides. Hence, it is vital to identify different landslide mechanisms, key drivers for rainfall-induced landslides, and risk assessment methods for adopting appropriate failure mitigation strategies. This study captures a comprehensive review and in-depth analysis based on 200 articles published in literature including authors own case studies to describe the risk management strategies of rain-induced landslides in tropical countries. First, a clear relationship between the rainfall patterns and the landslide events has been proposed through the comprehensive data sets reviewed. Then key influencing factors for landslides in the tropical region have been identified with in-depth discussion from past reported studies. Moreover, landslide risk assessment and management framework are discussed with the key steps involved. The framework provides a better-structured approach to discuss on identifying, analysing, evaluating, and managing risk associated with landslides. The complex geological conditions, lack of rainfall and impact data, and rapid change in land use make quantitative risk assessment challenging in the tropical region. The review finally recommends effective risk mitigation strategies from the authors' experience on past projects and reported literature case studies. The outcomes from the review are beneficial for engineers and authorities for adopting risk mitigation approaches in tropical regions
Wearable Accelerometer and Gyroscope Sensors for Estimating the Severity of Essential Tremor
No full textBackground: Several validated clinical scales measure the severity of essential tremor (ET). Their assessments are subjective and can depend on familiarity and training with scoring systems. Method: We propose a multi-modal sensing using a wearable inertial measurement unit for estimating scores on the Fahn-Tolosa-Marin tremor rating scale (FTM) and determine the classification accuracy within the tremor type. 17 ET participants and 18 healthy controls were recruited for the study. Two movement disorder neurologists who were blinded to prior clinical information viewed video recordings and scored the FTM. Participants drew a guided Archimedes spiral while wearing an inertial measurement unit placed at the mid-point between the lateral epicondyle of the humerus and the anatomical snuff box. Acceleration and gyroscope recordings were analyzed. The ratio of the power spectral density between frequency bands 0.5-4 Hz and 4-12 Hz, and the sum of power spectrum density over the entire spectrum of 2-74 Hz, for both accelerometer and gyroscope data, were computed. FTM was estimated using regression model and classification using SVM was validated using the leave-one-out method. Results: Regression analysis showed a moderate to good correlation when individual features were used, while correlation was high (r2 = 0.818) when suitable features of the gyro and accelerometer were combined. The accuracy for two-class classification of the combined features using SVM was 91.42% while for four-class it was 68.57%. Conclusion: Potential applications of this novel wearable sensing method using a wearable Inertial Measurement Unit (IMU) include monitoring of ET and clinical trials of new treatments for the disorder
Augmented reality, deep learning and vision-language query system for construction worker safety
No full textLow situational awareness contributes to safety incidents in construction. Existing Deep Learning (DL)-based applications lack the capability to provide context-specific and interactive feedback that is essential for workers to fully understand their surrounding environments. This paper proposes the Visual Construction Safety Query (VCSQ) system. The system encompasses real-time Image Captioning (IC), safety-centric Visual Question Answering (VQA), and keyword-based Image-Text Retrieval (ITR), integrated with head-mounted Augmented Reality (AR) devices. System validation includes benchmarks and real-world images. The ITR module posted high recall rates of 0.801 and 0.835 for Recall@5 and @10. The VQA module achieved an 89.7% accuracy rate, and the IC module had a SPICE score of 0.449. Feasibility tests and surveys confirmed the system's practical advantages in different construction scenarios. This study establishes an integration roadmap adaptable to future advancements in interactive DL and immersive AR
Tailored nanoparticles for magnetic hyperthermia: Highly stable aqueous dispersion of Mn-substituted magnetite superparamagnetic nanoparticles by double surfactant coating for improved heating efficiency
No full textThis study presents a significant advancement in cancer therapy through the application of Mn-substituted magnetite superparamagnetic (SPM) nanoparticles, highlighting the potential of magnetic fluid hyperthermia (MFH) as an effective modality. However, its clinical applications have been limited by challenges such as low heating performance, agglomeration of magnetic nanoparticles (MNPs) in blood veins, and cytotoxicity. To address these crucial issues, surface engineered MNPs were synthesised by adopting a reverse micelles-based co-precipitation approach that effectively overcomes MNP agglomeration, ensuring uniform dispersion of the nanoparticles. Through careful optimization of Mn ion substitution within magnetite, we have achieved a significant enhancement in the heating performance of the magnetite SPM nanoparticles. The substitution of Mn2+ ions in magnetite has notably increased the specific absorption rate (SAR) value, as evidenced by a remarkable 181% increase (SAR: 510 kW/kg) obtained using the Box Lucas Method. This enhancement can be attributed to the elevated saturation magnetization resulting from the appropriate cation distribution within the MNPs. Furthermore, the increase in spin relaxation time with higher Mn concentration also contributes to the improvement in SAR values as MNPs retain their magnetic moments for an extended period before relaxing, leading to enhanced energy dissipation and higher SAR values. The hemolysis assays demonstrated minimal hemolysis rates (90% cell viability) for Human Embryonic Kidney (HEK-293) cells across all compositions, further affirming the potential of these MNPs for clinical treatments. Overall, this study unveils a sustainable approach for cancer therapy using Mn-substituted magnetite SPM nanoparticles. Their remarkable heating performance and excellent biocompatibility make them promising for clinical applications in MFH