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Recent publications in Engineering

Baker, Stephanie, Xiang, Wei, and Atkinson, Ian (2021) Determining respiratory rate from photoplethysmogram and electrocardiogram signals using respiratory quality indices and neural networks. PLoS ONE, 16 (4). e0249843.
Continuous and non-invasive respiratory rate (RR) monitoring would significantly improve patient outcomes. Currently, RR is under-recorded in clinical environments and is often measured by manually counting breaths. In this work, we investigate the use of respiratory signal quality quantification and several neural network (NN) structures for improved RR estimation. We extract respiratory modulation signals from the electrocardiogram (ECG) and photoplethysmogram (PPG) signals, and calculate a possible RR from each extracted signal. We develop a straightforward and efficient respiratory quality index (RQI) scheme that determines the quality of each moonddulation-extracted respiration signal. We then develop NNs for the estimation of RR, using estimated RRs and their corresponding quality index as input features. We determine that calculating RQIs for modulation-extracted RRs decreased the mean absolute error (MAE) of our NNs by up to 38.17%. When trained and tested using 60-sec waveform segments, the proposed scheme achieved an MAE of 0.638 breaths per minute. Based on these results, our scheme could be readily implemented into non-invasive wearable devices for continuous RR measurement in many healthcare applications.

Tucker, Robert, Khatamifar, Mehdi, Lin, Wenxian, and McDonald, Kyle (2021) Experimental investigation of orientation and geometry effect on additive manufactured aluminium LED heat sinks under natural convection. Thermal Science and Engineering Progress, 23. 100918.
The continued adaptation of light-emitting diodes (LEDs) presents challenges for heat dissipation. LEDs are considered to be high power density devices, as such effective thermal management is imperative for extended usage. In this study, new design considerations such as adapting middle fin, fin height gradient towards the centre of the heat sink, along with fin perforations and a spiral cut out of the central pillar have been incorporated into heat sinks to assist convection. The heat sinks were manufactured out of aluminium alloy (AlSi10Mg) using the selective laser melting (SLM) method. The effects of orientation on the heat transfer of different heat sink geometries were experimentally studied under natural convection conditions. The performance of six different geometries with 6, 8 and 10 long fins (6LF, 8LF and 10LF) with and without middle fins were evaluated under three different heat flux conditions (471.57 , 943.14 and 1257.52 ) for 10 different orientation angles (0-90). The higher fin density heat sinks are found to have lower orientation dependency. The convective fluid flow of the higher fin density geometries is significantly hindered by the overlapping of thermal boundary layers. The increase in the Rayleigh number has the most significant effect on the 6LF heat sink. The overall Nusselt number correlations for the 6LF, 8LF and 10LF heat sinks with short fins are and , respectively. Removing short fins improved heat transfer rate for all heat sinks.

Dong, Liqiang, Lin, Wenxian, and Khatamifar, Mehdi (2021) Experimental study on the intrusion and stratification produced by confined laminar and turbulent round fountains. International Journal of Heat and Fluid Flow, 89. 108785. pp. 1-26.
In this paper, high-speed cameras and flow visualization techniques are used to investigate the behavior of the ‘fountain filling box’ flow resulted from releasing a round fountain in a homogeneous quiescent fluid in a cylindrical container over the ranges of 1.0⩽Fr⩽20.0,102⩽Re⩽1502, and 27.9⩽λ⩽48.75, where Fr,Re and λ are the Froude number, the Reynolds number, and the dimensionless radius of the container, respectively, with λ non-dimensionalized by the fountain source radius. The results show the transition of the flow behavior of the fountain and its secondary flows (i.e., the intrusion, reversed flow and stratification) from laminar to turbulent with increasing Fr, and turbulence of the flow strengthened with increasing Re. For intermediate (e.g., Fr=3.0) and forced turbulent fountains (e.g., Fr=5.0, 8.0, 15.0) with a specific λ, the non-dimensionalized time-scale for the intrusion front to impinge upon the sidewall, τw, is nearly constant for Re≳500. This is because the secondary intrusion flow is dominated by the wall-jet and buoyancy-inertial regimes where the non-dimensionalized intrusion front velocity, vi, is only time-dependent (vi~τ-1/2) or time-dependent but also under the influence of Fr (vi~Fr-1/2τ-1/4). However, τw for the fountains of Re≲204 is significantly different, which may result from the change in the dominant regime for the intrusion or the interaction between the upflow, downflow of the fountain and the ambient fluids. Furthermore, it is found that the non-dimensionalized quasi-steady development rate of the stratification, vs, increases with Fr, but decreases with Re, since the diffusion effect is suppressed with decreasing Fr or increasing Re.

Lal, Alvin, and Datta, Bithin (2021) Optimal pumping strategies for the management of coastal groundwater resources: application of Gaussian Process Regression metamodel-based simulation-optimization methodology. ISH Journal of Hydraulic Engineering. (In Press)
The present study utilizes a coupled simulation-optimization (S-O) methodology to develop a multi-objective management strategy for a coastal aquifer system. The aim of the multi-objective management model is to maximize pumping from freshwater wells (FWs) and minimize pumping from the barrier wells (BWs), while keeping salinity concentration in the aquifer within pre-specified limits (optimization constraint). To achieve computational feasibility of the management model, the numerical simulation model is substituted by the relatively new Gaussian Process Regression (GPR) metamodels. The GPR models are used to approximate coastal aquifer responses to variable transient pumping patterns from FWs and BWs. Prediction capabilities of the developed GPR metamodels are quantified using standard statistical parameters. Once trained and validated, the GPR metamodels are coupled to a multi-objective genetic algorithm optimization model and used to prescribe optimal groundwater pumping patterns. The outcomes of this study establishes the potential applicability of the GPR metamodel-based S-O model for developing sustainable coastal groundwater management strategies, which can utilize accurate and efficient prediction of management strategy impacts on the saltwater intrusion (SI) process when the optimal management policy development is based on the trained metamodel predictions. Once implemented, the developed strategy can help in controlling SI in coastal aquifer systems.

Staunton, Kyran M., Crawford, Jacob E., Liu, Jianyi, Townsend, Michael, Han, Yu, Desnoyer, Mark, Howell, Paul, Xiang, Wei, Burkot, Thomas R., Snoad, Nigel, and Ritchie, Scott A. (2021) A low-powered and highly selective trap for male Aedes (Diptera: Culicidae) surveillance: the male Aedes sound trap. Journal of Medical Entomology. (In Press)
As Aedes aegypti (Linnaeus, Diptera: Culicidae) expands its global distribution and vectors a range of debilitating arboviruses there is an increased need for enhanced mosquito surveillance. Consequently, we developed a Male Aedes Sound Trap (MAST) that requires minimal power and is highly species-specific. Two different versions of the MAST were developed, one that uses synthetic pyrethroid to kill captured mosquitoes (MAST Spray) and another which has an internal divider to create a killing chamber in which a sticky panel can be placed to capture mosquitoes (MAST Sticky). We compared weekly capture rates of male Ae. aegypti and bycatch from the two MAST versions to those from BG-Sentinel (BGS) traps and Sound-producing BG-Gravid Aedes Traps (SGATs) throughout Cairns, northern Australia. Weekly mean male Ae. aegypti catches did not significantly differ between trap types. However, the rate of positive weekly detections of male Ae. aegypti was lower for the MAST Sticky than the other three trap types. The MASTs sampled significantly fewer mosquitoes other than male Ae. aegypti, than either the BGS trap or the SGAT. Also, the MASTs and SGATs all caught significantly less non-Culicidae bycatch than the BGS traps. Consequently, we have developed a versatile male Ae. aegypti trap which is potentially of great benefit to Ae. aegypti surveillance programs.

Wheatley, Greg, and Zaeimi, Mohammad (2021) Front impact attenuator design for a race car. International Journal of Crashworthiness. (In Press)
This paper outlines the design, analysis and physical testing of the material for the front impact attenuator for the Motorsports car. The material selected was a 20 mm thick panel of veiled polypropylene honeycomb. The design programme Solidworks was used to produce three impact attenuator geometries for analysis – a solid block, a three-tier pyramid and a four-tier pyramid. The impact attenuator was simplified to solid blocks specified with the honeycomb material strengths and tested in ANSYS 14.0. The simulations did indicate that the four-tier pyramid had the greatest energy absorption behaviours. Two full size prototypes were manufactured and destructively tested. The force-displacement curve determined that prototype MKII achieved total energy absorption of 7591 J. The average deceleration was 17.66 g and maximum deceleration was 30.58 g. The polypropylene honeycomb energy absorption and deceleration values comply with FSAE requirements.

Lal, Alvin, and Datta, Bithin (2021) Application of the group method of data handling and variable importance analysis for prediction and modelling of saltwater intrusion processes in coastal aquifers. Neural Computing and Applications, 33. pp. 4179-4190.
Data-driven mathematical models are powerful prediction tools, which are utilized to approximate solution responses obtained using numerical saltwater intrusion simulation models. Employing data-driven prediction models as a replacement of the complex groundwater flow and transport models enables prediction of future scenarios. Most important, it also helps save computational time, effort and requirements when developing optimal coastal aquifer management methodologies using complex and large-scale coupled simulation-optimization models. In this study, a new data-driven mathematical model, namely group method of data handling (GMDH)-based prediction models, is developed and utilized to predict salinity concentration in a coastal aquifer by mimicking the responses of a variable-density flow and solute transport numerical simulation model. For comparison and evaluation purpose, the prediction performances of GMDH models were compared with well-established support vector machine regression and genetic programming based models. In addition, one important characteristic of the GMDH models is explored and evaluated, i.e. the ability to identify a set of most influential input predictor variables (pumping rates) that had the most significant impact on the outcomes (salinity concentration at monitoring locations). To confirm variable importance, 3 tests are conducted in which new GMDH models are constructed using subsets of the original datasets. In TEST 1, new GMDH models are constructed using a set of most influential variables (consisting of pumping rates at selected locations) only. In TEST 2, a subset of 20 variables (10 most and least influential variables) is used to develop new GMDH models. In TEST 3, a subset of the least influential variables is used to develop GMDH models. The performance evaluation results demonstrate that GMDH models developed using the entire dataset had reasonable prediction accuracy and efficiency. The comparison performance evaluation results for the three test scenarios highlighted the importance of the appropriate selection of relevant input pumping rates when developing accurate prediction models. The results suggested that incorporating the least influential variables deteriorate the accuracy of the prediction models; thus, considering the most influential pumping rates it is possible to develop more accurate and efficient salinity prediction models. Overall, the evaluation results from this study establish that the GMDH models and the inherent input variable ranking capability can be utilized as accurate and efficient coastal saltwater intrusion prediction models. Hence, GMDH models are viable saltwater intrusion modelling tools, which can be employed in future regional-scale saltwater intrusion prediction and management investigations.

Steinemann, Anne, Nematollahi, Neda, Rismanchi, Behzad, Goodman, Nigel, and Kolev, Spas D. (2021) Pandemic products and volatile chemical emissions. Air Quality, Atmosphere and Health, 14. pp. 47-53.
The recent pandemic (COVID-19) has seen a sweeping and surging use of products intended to clean and disinfect, such as air sprays, hand sanitizers, and surface cleaners, many of which contain fragrance. However, exposure to fragranced cleaning products has been associated with adverse effects on human health. Products can emit a range of volatile chemicals, including some classified as hazardous, but relatively few ingredients are disclosed to the public. Thus, relatively little is known about the specific emissions from these products. This study investigates the volatile organic compounds (VOCs) emitted from "pandemic products" that are being used frequently and extensively in society. In addition, among these emissions, this study identifies potentially hazardous compounds, compares so-called green and regular versions of products, and examines whether ingredients are disclosed to the public. Using gas chromatography/mass spectrometry, 26 commonly used pandemic products, including 13 regular and 13 so-called green versions, were analyzed for their volatile emissions. Product types included hand sanitizers, air disinfectants, multipurpose cleaners, and handwashing soap. All products were fragranced. The analyses found the products collectively emitted 399 VOCs with 127 VOCs classified as potentially hazardous. All products emitted potentially hazardous compounds. Comparing regular products and green products, no significant difference was found in the emissions of the most prevalent compounds. Further, among the 399 compounds emitted, only 4% of all VOCs and 11% of potentially hazardous VOCs were disclosed on any product label or safety data sheet. This study reveals that pandemic products can generate volatile emissions that could pose risks to health, that could be unrecognized, and that could be reduced, such as by using fragrance-free versions of products.

Nematollahi, Neda, Weinberg, Justine Lew, Flattery, Jennifer, Goodman, Nigel, Kolev, Spas D., and Steinemann, Anne (2021) Volatile chemical emissions from essential oils with therapeutic claims. Air Quality, Atmosphere and Health, 14. pp. 365-369.
Essential oils emit many volatile organic compounds (VOCs), with some considered potentially hazardous. However, little is known about specific emissions from essential oils that make therapeutic claims for health and well-being. This study investigated VOCs emitted from 14 commercially available essential oils with therapeutic claims, such as beneficial for coughs, colds, flus, relaxation, sleep, tension, headaches, stress, or skin irritation. The essential oils were selected from different brands and types, such as tea tree oil, lavender oil, eucalyptus oil, geranium oil, peppermint oil, bergamot oil, orange oil, and oil blends. Analyses were performed using headspace gas chromatography/mass spectrometry (GC/MS). The analyses found 1034 VOCs emitted from the 14 essential oils, representing 378 VOC identities. The most prevalent VOCs (in more than 90% of the oils) were acetaldehyde, alpha-phellandrene, alpha-pinene, camphene, limonene, methanol, terpinolene, 3-carene, acetone, beta-phellandrene, ethanol, and gamma-terpinene. Among the 1034 VOCs emitted, 251 VOCs, representing 60 VOC identities, are classified as potentially hazardous. The most prevalent potentially hazardous VOCs were acetaldehyde, limonene, methanol, acetone, ethanol, and 3-carene. Toluene was found in more than 70% of the essential oils. Each of the essential oils emitted 9 or more potentially hazardous VOCs. Fewer than 1% of all VOCs identified and fewer than 1% of all potentially hazardous VOCs were listed on any essential oil label, safety data sheet, or website. Results from this study provide new findings on VOC emissions from essential oils with therapeutic claims, which can help to improve public awareness about potential exposures and risks.

Li, Xingshuo, Wen, Huiqing, Hu, Yihua, Du, Yang, and Yang, Yong (2021) A comparative study on photovoltaic MPPT algorithms under EN50530 dynamic test procedure. IEEE Transactions on Power Electronics. (In Press)
Dynamic performance of maximum power point tracking (MPPT) algorithms is important to ensure high-power output under practical operating conditions. In this article, after reviewing three dynamic test procedures, including stepped operation procedure, day-by-day operation procedure, and EN50530 dynamic test procedure, three typical MPPT algorithms such as the fixed-step-size perturb and observe (P&O), variable-step-size incremental conductance, and hybrid-step-size beta method are evaluated experimentally under the EN50530 dynamic test procedure. Two dynamic EN50530 test sequences are adopted for the performance evaluation to cover different irradiance changing conditions. The PV model for EN50530 dynamic test sequences is built, and the effects of wrong-step changes by using three MPPT algorithms are analyzed systematically. The experimental comparison of three MPPT algorithms in terms of the tracking routines, accumulated energy, and tracking efficiency is presented. The research shows that the 0.5% fixed-step-size P&O may fail to track the MPP due to the tracking drift, whereas the beta algorithm exhibits the highest tracking efficiency under both dynamic sequences. The average tracking efficiency improvement of the beta algorithm compared with other two algorithms are experimentally measured as 24.2% and 18.8%, respectively.

Madhukumar, Neethu, Wang, Eric, Zhang, Yi-Fan, and Xiang, Wei (2021) Consensus forecast of rainfall using hybrid climate learning model. IEEE Internet of Things Journal. (In Press)
Rainfall event forecasting is prominently done using climate models (CMs) to produce multiple forecasts for the same rainfall event. The best forecast is complicated to find and hence has not yet been explored in the CMs. Recent advances in deep learning methods have provided an exceptional ability to investigate intricate weather patterns from big climate data. In this paper, a hybrid climate learning model (HCLM) is proposed that utilises both the CM and the deep learning models for improving the rainfall forecast. More specifically, a probabilistic multi-layer perceptron (PMLP) network evaluates multiple forecasts from the CM-generated forecasts and selects the best one. The selected forecast is next passed onto a hybrid deep long short term memory (HD-LSTM) network, which looks back and learns the relationship of the selected forecast with corresponding rainfall and temperature observations to produce the next-day rainfall forecast. The experimental results from various climate zones in Australia show that the HCLM outperforms existing state-of-the-art climate and deep learning models.

Wheatley, Greg, and Rubel, Robiul Islam (2021) Analysis of conveyor drive power requirements in the mining industry. Acta Logistica, 8 (1). pp. 37-43.
This article presents the analysis of conveyor drive power requirements for three typical mining conveyors. One of the conveyors was found not to be able to start when fully loaded. The analysis indicates that two of the conveyors are adequately powered while one is underpowered. This was found to be primarily the result of the maximum tonnage of the two adequately powered conveyors being 1500 tonnes per hour (TPH) while the inadequately powered conveyor was classed with a maximum tonnage of 1800 TPH. It is recommended that the current draw for each motor when fully loaded be measured. This will be compared to the design. Further analysis was done to allow 2000 TPH on all conveyors. The required upgraded drive size is presented. This article does not address the structural adequacy of the supporting structure. Rather, only the capabilities of the conveyor belt and drives to transport the required TPH.

Vuppaladadiyam, Arun K., Antunes, Elsa, Sanchez, Paula Blanco, Duan, Huabo, and Zhao, Ming (2021) Influence of microalgae on synergism during co-pyrolysis with organic waste biomass: a thermogravimetric and kinetic analysis. Renewable Energy. (In Press)
The synergistic influence of microalgae on the two forms of organic waste biomasses, namely biomass wastes (BW) and its digested form (DBW), during co-pyrolysis was evaluated based on the thermal decomposition behaviour, gas yields, extent of thermal decomposition and reaction kinetics. The biomasses and their blends were co-pyrolysed at three different heating rates (10, 15 and 20C/min) in a thermogravimetric analyzer coupled with a mass spectrometer. Initial assessment, based on TG-DTG data, revealed that the thermal degradation can be divided into three zones (50-150C, 150-550C and 550-800C) for all the biomasses and their blends. The thermogravimetric data was used to evaluate the kinetic triplet, which include apparent activation energy (Ea), pre-exponential factor (A) and reaction mechanism, f(a). Semi-quantitative method was used to quantify the gas species, H2, CO2 and CO were dominant species, implying the water gas reactions and oxidation reactions were predominant. The synergistic influence of microalgae was clearly evident in terms of reaction kinetics, as noted in the reduction in the apparent activation energy and increase in the total gas yields. The obtained kinetic triplet and thermodynamic parameters are expected to facilitate the design and optimization of co-pyrolysis of microalgae with other forms of organic wastes.

Varsha, S.S.V., Vuppaladadiyam, Arun K., Shehzad, Farrukh, Ghaedi, Hosein, Murugavelh, S., Dong, Weiguo, and Antunes, Elsa (2021) Co-pyrolysis of microalgae and municipal solid waste: a thermogravimetric study to discern synergy during co-pyrolysis process. Journal of the Energy Institute, 94. pp. 29-38.
Synergism during the co-pyrolysis of microalgae (CC), municipal solid waste (MSW), and their blends(CC/MSW) (w/w %), 25/75 (CM-1), 50/50 (CM-2), and 75/25 (CM-3), was evaluated based on thermal decomposition pattern, evolved gases, rate and extent of thermal decomposition, and kinetic parameters. Three stages of devolatilization attributed to dehydration, devolatilization of major structural com-pounds of biomass and decomposition of solid residues were noticed during the co-pyrolysis of biomass samples. The main pyrolysis stages for CC, MSW, CM-1, CM-2 and CM-3 were 175e520, 151-523, 164-504,168-510, 160e501 °C, respectively. Microalgae, CC, appeared to be thermally resistant, while MSW is noticed to be thermally sensitive. The kinetics analysis was studied by deconvoluting the DTG profile into independent stages, followed by application of isoconversional methods to evaluate the activation energy and the pre-exponential factor. Furthermore, the reaction mechanism of each stage was determined by using the master plot method. The semi-quantitative method was used to evaluate the evolved gases and CO, CO2 and H2 were noticed to be the dominant gas species. The obtained thermal and kinetic data for co-pyrolysis of microalgae and MSW can serve are basis for scale-up and reactor design of pyrolysis process for similar kind of waste streams.

Khakbaz, Hadis, Ruberu, Kalani, Kang, Lingzhi, Talebian, Sepehr, Sayyar, Sepidar, Filippi, Benjamin, Khatamifar, Mehdi, Beirne, Stephen, and Innis, Peter C. (2021) 3D printing of highly flexible, cytocompatible nanocomposites for thermal management. Journal of Materials Science, 56. pp. 6385-6400.
Highly flexible biocompatible materials that are both thermally conductive and electrically insulating are important for implantable and wearable bioelectronics applications. The ability to thermally process these materials into useful structures using additive manufacturing approaches opens up new opportunities for its use in bespoke structures. Here we investigate the three-dimensional (3D) printing of a medical-grade thermoplastic polyurethane (PU) elastomer, which is thermally insulating and enhance its thermal and mechanical properties through the incorporation of boron nitride (BN) as a filler. Via a simple solution compounding approach, a highly flexible and thermally conductive BN nanoparticle/ PU composite has been developed and subsequently processed into simple bio-scaffolds structures via a 3D pneumatic melt extrusion printing process. The addition of up to 20% w/w of BN to the PU significantly enhances the tensile modulus by 659%, from 1.74 to 13.2 MPa, while supporting high mechanical flexibility. The thermal conductivity of 20% w/w BN/PU composite increases by 74% with respect to the unmodified PU. The 3D printed BN/PU composite scaffolds exhibit good biocompatibility and cell attachment enhancement with L929 fibroblast cells.

Islam, Md Anwarul, Jacob, Mohan V., and Antunes, Elsa (2021) A critical review on silver nanoparticles: from synthesis and applications to its mitigation through low-cost adsorption by biochar. Journal of Environmental Management, 281. 111918.
Silver nanoparticles are one of the most beneficial forms of heavy metals in nanotechnology applications. Due to its exceptional antimicrobial properties, low electrical and thermal resistance, and surface plasmon resonance, silver nanoparticles are used in a wide variety of products, including consumer goods, healthcare, catalysts, electronics, and analytical equipment. As the production and applications of silver nanoparticles containing products increase daily, the environmental pollution due to silver nanoparticles release is increasing and affecting especially the aqueous ecosystem. Silver nanoparticles can kill useful bacteria in soil and water, and bioaccumulate in living organisms even at low concentrations from 10−² to 10 μg/mL silver can show antibacterial effect. On the other hand, the maximum silver discharge limit into freshwater is 0.1 μg/L and 3.2 μg/L for Australia and the USA, respectively. To reduce its toxic consequences and meet the regulatory guidelines, it is crucial to remove silver nanoparticles from wastewater before it is discharged into other water streams. Several technologies are available to remove silver nanoparticles, but the adsorption process using low-cost adsorbents is a promising alternative to mitigate silver nanoparticle pollution in the bulk stage. As one of the low-cost adsorbents, biochar produced from the biomass waste could be a suitable adsorbent. This review focuses on collating the latest evidence on silver nanoparticle production, applications, environmental consequences, and cost-effective technological approaches for silver removal from wastewater.

Belson, Bruce, Xiang, Wei, Holdsworth, Jason, and Philippa, Bronson (2021) C++20 coroutines on microcontrollers - what we learned. IEEE Embedded Systems Letters, 13 (1). pp. 9-12.
Coroutines will be added to C++ as part of the C++20 standard. Coroutines provide native language support for asynchronous operations. This study evaluates the C++ coroutine specification from the perspective of embedded systems developers. We find that the proposed language features are generally beneficial but that memory management of the coroutine state needs to be improved. Our experiments on an ARM Cortex-M4microcontroller evaluate the time and memory costs of coroutines in comparison with alternatives, and we show that context switching with coroutines is significantly faster than with thread-based real time operating systems. Furthermore, we analysed the impact of these language features on prototypical IoT sensor software. We find that the proposed language enhancements potentially bring significant benefits to programming in C++ for embedded computers, but that the implementation imposes constraints that may prevent its widespread acceptance among the embedded development community.

Timbs, Kalen, Khatamifar, Mehdi, Antunes, Elsa, and Lin, Wenxian (2021) Experimental study on the heat dissipation performance of straight and oblique fin heat sinks made of thermal conductive composite polymers. Thermal Science and Engineering Progress, 22. 100848.
Heat sink can effectively dissipate heat in a range of thermal applications for improved performance and reliability. Thermally conductive polymer composites show great promise in solving the overheating issue in electronic devices. This experimental study investigates the heat dissipation performance of straight and oblique fin heat sinks made of thermally conductive polymer composites under forced convection conditions over , where Re is the Reynolds number. The heat sinks were 3D printed using Ice9 Flex (carbon filled polymer), copper filled filament (polylactic acid with 80 wt% copper particles) and bronze filled filament (polylactic acid with 80 wt% bronze particles), respectively. Oblique fins were found to effectively reduce the thermal resistance of heat sinks, increase the convective heat transfer and the inner-fin velocity which results in lower pressure drop, in comparison to straight fins. The carbon-filled polymer (Ice9 Flex) heat sink was shown to have much superior heat dissipation capability compared to metal filled filament heat sinks.

Wheatley, Greg, and Popoola, Samuel (2021) Autonomous transmission control of a 2017 Yamaha Grizzly 700 all-terrain vehicle. Scientific Journal of Silesian University of Technology. Series transport, 110. pp. 183-198.
Investigation on a designed and modified standard automatic transmission for a 2017 Yamaha Grizzly All-Terrain Vehicle was carried out to allow it to be controlled remotely and autonomously while maintaining its ability to be manually operated. The vehicle is a part of a project named AutoWeed. This project aims at developing a vehicle which can be used in the Australian outback to control and eradicate weeds. Preliminary tests were conducted on the vehicle to determine the performance parameters required to replace the movement supplied by the operator. Several devices used to achieve this motion were explored. It was concluded that the Motion Dynamics HB-DJ806 - LALI10010 electromechanical linear actuator be used as a proof of concept device for this application. This device is capable of exerting 200 N at 35 mm/seconds. It has a stroke length of 50 mm and was powered by a 12V DC motor, which drew 3 amps at maximum load. Through testing, it was found that the selected actuator did not have enough stroke length to cycle through the five gears on the ATV. This error was rectified allowing the system to function as intended. To achieve a reliable design, however, the Linak LA14 actuator was purchased as a final design as it was stronger, faster and had feedback capabilities. Before procurement, the new actuator was digitally modelled using SolidWorks 2017 and 3D printed to confirm the mounting position and method. An ANSYS FEA was conducted on all the custom-made components including the actuator bracket and mounting plate to ensure reliability. The bracket model was manufactured using 3D printing from ABS. It was recommended that for reliability, the bracket should be constructed from a stronger material such as aluminium. The results gained from testing proved that the autonomous transmission system implemented was reliable and repeatable. This was justified as the system achieved a 100% success rate when cycling through gears.

Malekzadeh, M., Sivakugan, Siva, and Clark, M.W. (2021) Effect of aqueous environment on sedimentation of dredged mud and kaolinite. Marine Georesources & Geotechnology. (In Press)
Port development results in production of large quantities of dredged marine sediments. Once dredged, sediments often have high water contents and are pumped to near-shore or in-water bunded marine impoundments for port expansion. However, dredged material disposal to freshwater onshore or empty impoundments typically changes sedimentation conditions that may change the effective grain-size distribution, mineral specific surface areas, settling particle orientations, resulting in settling rate changes. Salinity, temperature, water content, mineralogy, filling rate, and organic matter content may also influence sediment settlement and resulting consolidation. This study investigates the effect of salinity and sediment mineralogy on sediment settlement behaviour when deposited in saltwater, freshwater, or to empty ponds. For this purpose, slurries of dredged mud and kaolinite with water contents of 1.7 times their liquid limit were prepared and disposed into a series of 1000 mm long, 50 mm wide, and 500 mm high settlement columns. Result shows that the sediments settle faster in saltwater than freshwater or air, through divalent surface complexation and flocculation provided by seawater Ca and Mg. However, this is true if the salinity remains below 10 PSU, but the mixed mineral dredge spoil ultimately provides the densest sediment and lowest water sediment interface.

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