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Item Metadata only 14th Australasian Fluid Mechanics Conference - Preface(Elsevier Science Inc, 2003) Dally, B.; Kelso, R.; Nathan, G.; Denier, J.Item Metadata only 2D modelling of inclined intergranular stress corrosion crack paths(Wiley Publishing, 2017) Griggs, J.; Gamboa, E.; Lavigne, O.Inclined high pH stress corrosion cracking (SCC) is a type of intergranular environmen- tal cracking in gas pipelines, which differs from typical SCC by propagating at an angle from the wall direction. Investigations of Australian and Canadian inclined SCC colonies have not provided a clear indicator of a cause for the abnormal crack growth direction. This paper addresses the possibility of crack tip strain enhanced electrochemistry causing the inclination. Potentiodynamic tests were conducted to quantify the influence of strain on the electrochemistry, and strain was found to increase current density up to 300% in the SCC region. A model was developed that incorporates crack tip strain driven SCC growth, which showed good agreement with field grown cracks, and the aspect ratio of the grains was shown to have an effect on the inclination angle. The result s indicate that crack tip strain enhanced electrochemistry is a plausible cause for inclined SCC.Item Metadata only 3D framework combining CFD and MATLAB techniques for plume source localization research(Pergamon-Elsevier Science Ltd, 2013) Awadalla, M.; Lu, T.; Tian, Z.; Dally, B.; Liu, Z.Sudden release of chemical gas in indoor environments such as office like buildings or industrial warehouses could become hazardous. This has highlighted the need to localize the source of contaminant in least time possible using plume-tracing mobile robots. A simulation framework is outlined for developing, optimizing and testing plume-tracing algorithm in a complex environment. In the first part of the framework, fluid flow process and contaminant transport in a virtual environment is generated by dedicated computational fluid dynamics (CFD) software packages. In the second part of the framework, the exported data of airflow vectors and contaminant concentration from the CFD results is used for the robot to find the source of the contaminant in a three-dimensional search pattern. The virtual robot is built using an in house developed MATLAB code. Several case studies have been addressed at the same complex environment, however at different source locations and source heights as well as at different initial robot start positions. Based on the results, the paper shows the capability of the 3D plume-tracing framework to find the location of the source for strong 3D indoor plumes when tested at different cases. © 2013 Elsevier Ltd.Item Metadata only 3D stockpile modelling and quality calculation for continuous stockpile management(Elservier Science BV, 2015) Zhao, S.; Lu, T.; Koch, B.; Hurdsman, A.Abstract not availableItem Metadata only 802.11 WLAN OWPT measurement algorithms and simulations for indoor localization(Springer, 2010) Wang, X.; Lu, T.; Ao, S.This paper discussed novel algorithms for synchronizations and time resolution improvements of One Way Propagation Time (OWPT) measurements in the 802.11 Wireless Local Area Network (WLAN). In OWPT measurements, the Mobile Station (MS) records each 802.11 Beacon frame’s arrival time. The Beacon frame’s arrival time minus its Timestamp, which is recorded when the Beacon frame is transmitted from an Access Point (AP), is the Beacon frame’s Propagation Time. The Propagation Time represents the distance between the MS and the AP. Rather than microseconds (μs) time resolution Timestamp, the MS could use its high precision clock to record the Beacon frame’s arrival time in nanoseconds (ns). The first part of this paper proposes algorithms which can utilize the ns resolution arrival Time to improve the OWPT measurements time resolution from μs to ns and to highly synchronize the MS with all APs. These algorithms provide an opportunity to apply OWPT in 802.11 WLAN for highly accurate indoor localization. The second part discusses the possibility to utilize existing software and hardware platform to realize the proposed algorithms. At the end of this paper, the shortages of existing MS timing ability were raised and several options are provided for future researches to improve MS timing ability for OWPT application.Item Metadata only A 2-D DNS investigation of extinction and reignition dynamics in nonpremixed flame-vortex interactions(Elsevier Science Inc, 2008) Venugopal, R.; Abraham, J.Two-dimensional (2-D) DNS investigations of extinction and reignition dynamics during interactions of laminar nonpremixed flames with counterrotating vortex pairs are performed. The length and velocity scales chosen for the vortices are representative of those in the near fields of high-Reynolds-number jets such as those occurring in Diesel engines. The governing equations are solved with sixth-order spatial discretization and fourth-order time integration. Chemistry is modeled as an irreversible single-step reaction. Local extinction along the symmetry axis, followed by reignition, is observed. The extinction is characterized by strong unsteady effects, which are captured well by 1-D transient diffusion flamelet libraries, provided the time-history of the instantaneous scalar dissipation rate is taken into account. On the other hand, reignition is essentially a 2-D phenomenon involving flame–flame interactions, which are favored for smaller vortices and increasing flame curvature. The effects of unsteadiness and curvature on extinction and reignition are carefully assessed through parametric studies involving a range of vortex and flame characteristics. The interaction outcomes are summarized on Reynolds–Damköhler number (Re–Da) diagrams, which show the combined effects of unsteadiness and curvature on extinction and reignition. The implications of the observed interaction outcomes for turbulent combustion modeling in the near fields of jet diffusion flames are discussed.Item Metadata only A 3DOF system for 3 dimensional stockpile surface scanning using laser(IEEE, 2011) Lu, T.; Zhao, S.; Xu, S.; Koch, B.; Hurdsman, A.; IEEE Conference on Industrial Electronics and Applications (6th : 2011 : Beijing, China)In material handing operations, raw materials are often stacked in a number of layers and subsequently reclaimed by benches. The quality grade may be different between layers. Also, the blending effect happens simultaneously with the stacking and reclaiming operations, how to meet the target grade required by the customers while lowering operation costs are rising academic concerns. By acquiring the shapes and dimensions of the layers of 3D stockpiles, the flows of bulk materials can be tracked, the compositions and distributions predicted, planned and controlled with much ease leading to increased efficiencies in Australia’s current bulk handling infrastructure, consequently increasing export potential and reducing costs. This paper describes a 3DOF laser scanning system which was designed to accurately measure, model and record the quantity of bulk solids in a laboratory environment. Pilot experiments and results demonstrate good, precise and fast performance of the system.Item Open Access A baseline-free and non-contact method for detection and imaging of structural damage using 3D laser vibrometry(Wiley, 2017) Aryan, P.; Kotousov, A.; Ng, C.; Cazzolato, B.Abstract not availableItem Open Access A biochar-producing, dung-burning cookstove for humanitarian purposes(Elsevier, 2014) Birzer, C.; Medwell, P.; MacFarlane, G.; Read, M.; Wilkey, J.; Higgins, M.; West, T.; Vidan, A.; Shoag, D.Abstract not availableItem Metadata only A biomechanical investigation of the anteromedial and posterolateral bands of the porcine anterior cruciate ligament(Professional Engineering Publishing Ltd, 2009) Zhou, T.; Grimshaw, P.; Jones, C.The bipartite nature of the porcine anterior cruciate ligament has been documented, but its biomechanics have not been investigated. The need for such knowledge has recently been heightened with xenografting advances such as the introduction of the porcine patellar tendon as a human anterior cruciate ligament graft. The aim of this study is to compare the biomechanical properties of the intact anterior cruciate ligament with that of its two bands. 15 intact porcine anterior cruciate ligament–bone, 15 anteromedial band–bone, and 15 posterolateral band–bone complexes were prepared for tensile testing at 0.33 mm/s. Structural (load, deformation, stiffness, and energy absorbed) and material (stress, strain, modulus, and strain energy density) properties were analysed. Analysis of variance identified significantly higher ultimate load, stiffness, and energy absorbance in the intact porcine ligament when compared with its anteromedial band (p = 0.028). However, the intact ligament was only significantly higher in ultimate load when compared to its posterolateral band (p = 0.031). All ligament–bone complexes failed at similar deformations and strains, suggesting a strain-dependent failure mechanism. The intact porcine anterior cruciate ligament exhibited higher ultimate load, stiffness, and energy absorption than its two bands in isolation. The posterolateral band of the porcine anterior cruciate ligament constitutes a large proportion of the overall restraining function of the entire anterior cruciate ligament.Item Metadata only A combination of linear and nonlinear activation functions in neural networks for modeling a de-superheater(Elsevier Science BV, 2009) Mohammadzaheri, M.; Chen, L.; Ghaffari, A.; Willison, J.This paper deals with modeling a power plant component with mild nonlinear characteristics using a modified neural network structure. The hidden layer of the proposed neural network has a combination of neurons with linear and nonlinear activation functions. This approach is particularly suitable for nonlinear system with a low grade of nonlinearity, which can not be modeled satisfactorily by neural networks with purely nonlinear hidden layers or by the method of least square of errors (the ideal modeling method of linear systems). In this approach, two channels are installed in a hidden layer of the neural network to cover both linear and nonlinear behavior of systems. If the nonlinear characteristics of the system (i.e. de-superheater) are not negligible, then the nonlinear channel of the neural network is activated; that is, after training, the connections in nonlinear channel get considerable weights. The approach was applied to a de-superheater of a 325 MW power generating plant. The actual plant response, obtained from field experiments, is compared with the response of the proposed model and the responses of linear and neuro-fuzzy models as well as a neural network with purely nonlinear hidden layer. A better accuracy is observed using the proposed approach. © 2008 Elsevier B.V. All rights reserved.Item Metadata only A compact solution for the interface corner stress intensity factor of a cylindrical butt joint(Australian Journal of Mechanical Engineering, 2010) Chang, D.; Harding, S.; Australasian Congress on Applied Mechanics (6th : 2010 : Perth, Western Australia)A cylindrical butt joint is widely utilised in bi-materials structures. Numerous examples can be found in micro-electronics, medicine and composite areas. Such bi-material structures normally have a very strong stress concentration at the interface, which often characterised by linear solutions of the theory of elasticity leading to the appearance of stress singularities. These singular solutions play a very important role in failure assessment of such joints by fracture mechanics approaches. In this paper we develop a compact solution for the generalized stress intensity factor at the interface of a cylindrical bi-material joint loaded by remote tensile loading parallel to the axis of symmetry. Based on a careful numerical modelling, a simple equation maintaining simplicity and accuracy over the wide range of problem’s variables is suggested. Furthermore, the existence of scale effect on the interface corner stress intensity factor for a cylindrical butt joint structure is also discussed in detail.Item Metadata only A comparative approach of inverse modelling applied to an irradiative batch dryer employing several artificial neural networks(Pergamon-Elsevier Science Ltd, 2014) Mirsepahi, A.; Chen, L.; O'Neill, B.The present work has focused on a comparison between commonly employed artificial neural networks (ANNs) in engineering applications to identify the most efficient ANN for the inverse modelling of an irradiating furnace/dryer in terms of accuracy and computing time. To this end, several ANNs were designed, trained and employed to estimate the heat emitted during the irradiative batch drying process with the aid of NeuroSolution®.As part of the study, different ANNs were designed and trained to play the role of the inverse heat transfer model. The reasons for exploiting these ANNs were derived from various studies in the literature, in which ANNs were employed for engineering modelling purposes. The results showed that the multiple layer perceptron (MLP) with the Levenberg-Marquadt (LM) in the back propagation (BP) was the best ANN among the methods evaluated to solve the inverse heat estimation problems used in irradiative batch drying processes. An important advantage of the ANN method in comparison with the classical inverse heat transfer modelling approaches is that a detailed knowledge of geometrical and thermal properties of the system (such as wall conductivity, emissivity, etc.) is not required. Such properties are difficult to measure and may undergo significant changes during the temperature transient mode.In this study, genetic algorithms (GAs) have been employed to determine the key parameters of the employed ANNs. These parameters are normally found heuristically or by a trial and error brute force process. The results demonstrate that the aforementioned parameters may be estimated much more accurately and faster by the GA method. The performance of the networks has been improved as well and the number of required hidden layers has been discovered using a non trial-error method, which eliminates time-consuming repeating procedures and produces more accurate results. © 2014 Elsevier Ltd.Item Metadata only A comparative experimental study of robust sliding mode control strategies for underactuated systems(IEEE, 2018) Din, S.U.; Khan, Q.; Rehman, F.-U.; Akmeliawati, R.This paper presents a comprehensive comparative study for the tracking control of a class of underactuated nonlinear uncertain systems. A given nonlinear model of the underactuated system is, at rst stage, transformed into an input output form and the driving applied control input of the transformed system is then designed via four sliding mode control strategies, i.e., conventional rst order sliding mode control, second order sliding mode, fast terminal sliding mode, and integral sliding mode. At second stage, a ball and beam system is considered and the aforementioned four control design strategies are experimentally implemented. A comprehensive comparative study of the simulation and experimental results is then conducted which take into account the tracking performance, i.e., settling time, overshoots, robustness enhancement, chattering reduction, sliding mode convergences, and control efforts.Item Metadata only A comparative study of different burning time models for the combustion of aluminum dust particles(Elsevier, 2016) Bidabadi, M.; Poorfar, A.; Wang, S.; Bengt, S.Abstract not availableItem Metadata only A comparative study of n-heptane, methyl decanoate, and dimethyl ether combustion Characteristics under homogeneous-charge compression-ignition engine conditions(Elsevier Sci Ltd, 2009) Hoffman, S.; Abraham, J.Item Metadata only A comparative study on preparation of TiO₂ pellets as photocatalysts based on different precursors(Trans Tech Publications Ltd, 2005) Luo, Y.; Zou, L.; Hu, E.; Zhong, Z.Y.; Saka, H.; Kim, T.H.; Holm, E.A.; Han, Y.F.; Xie, X.S.The porous TiO2 pellets were prepared based on pigment grade titaina, P25 titania powder and titanium(IV) butoxide. The characterization was done with X-Ray diffraction, scanning electron microscopy and BET measurements. The result shows that TiO2 pellets by using titanium(IV) butoxide with some addictive have the best surface porosity, with specific surface area of 196.9m2/g. For pigment grade titania and P25 titania powder, it is still effective to enhance the surface area after reassembling. The surface area increased from 11.6 to 29.2 m2/g for pigment grade titania and from 50 to 84.4 m2/g for P25 titania powder. Furthermore, it has been investigated on how to optimize and get the highest surface area by controlling the sintering temperature, reaction temperature, pH of solution, and the amount of alcohol and addictive of surfactant during preparation. The experimental photocatalytic degradation of acetone and toluene was performed using titania pellets made from P25 titania powder.Item Metadata only A comparative study on the microstructures and mechanical properties of the Mg-xCa/Mn/Ce alloys and pure Mg(Elsevier, 2021) Zhao, D.; Li, G.; Li, P.; Zhou, J.; Cheng, K.; Liu, Y.; Yang, Y.; Duan, J.; Ghomashchi, R.; Wang, X.A comparative study on the microstructures and mechanical properties of the extruded Mg-xCa/Mn/Ce (x = 0.25, 0.5, 1, 2.0 wt%) alloys and pure Mg has been carried out. It was found that when the addition of Ca, Mn and Ce was more than 0.25 wt%, 0.5 wt% and 0.5 wt% respectively, microstructures with fine grain sizes smaller than 5 μm can be achieved by extruding at 375 ◦C with a extrusion ratio of 30 and a ram speed of 0.8 mm/s. While the grain size of pure magnesium extruded under the same condition was 26.6 μm. The addition of Ca, Mn or Ce has significant effects on the textures of the extruded Mg-xCa/Mn/Ce alloys. The maximum intensity peaks in PF and IPF of Mg are all deviated by a certain degree with the addition of Ca, Mn or Ce. In the 12 extrusion alloys, Mg-0.5Ca、Mg–2Mn and Mg–1Ce exhibited better mechanical properties, whose ultimate tensile strength and elongation are 243.6 MPa, 233.7 MPa, 321.5 MPa and 25.6%, 20.7%, 7.6%. While the ultimate tensile strength and elongation of as-extruded pure Mg is 173.8 MPa and 16.0% respectively. Mg-xCa and Mg-0.25Ce alloys with weak texture showed weaker tension-compression asymmetry. The experimental results showed that it is feasible to prepare fine grained (<5 μm) Mg-xCa/Mn/Ce alloys with much improved mechanical properties using conventional extrusion.Item Metadata only A comparative study on the use of black box modelling for piezoelectric actuators(Springer London Ltd, 2012) Mohammadzaheri, M.; Grainger, S.; Bazghaleh, M.In this article, different approaches of the use of black box modelling techniques for piezoelectric actuators are particularly addressed, regardless of the employed technique/algorithm. A modelling approach in this paper refers to two matters: the first, the role of black box techniques in modelling (i.e. if physics-based techniques are also involved in modelling; if so, how and to what extent). From this aspect, the spectrum of approaches ranges from those merged with/inspired by classical phenomenological models to an approach based on purely system identification-based techniques. The second aspect of modelling approaches, in this article, is the input variables to the model. Current and previous values of input voltage, previous values of the output (displacement), derivatives and extremum values of the system's input/output have been used as the inputs to the model so far. Both aforementioned aspects of modelling approaches are addressed appropriately in this article, and various modelling approaches in the literature are categorized and presented in a uniform and comparable manner, so that readers can easily identify research trends in this area and the gaps in the literature. One of the identified unanswered questions in the literature is whether the extremum values of the system's input/output should/should not be used as an input to black box models of piezoelectric actuators. There are works in the literature which have/have not used the aforementioned input variables, but there is no published investigation to evidently answer the proposed question. This article, in the last section, answers this question by reporting and discussing an experimental study.Item Metadata only A comparison of filter design structures for multi-channel acoustic communication systems(Acoustical Soc Amer Amer Inst Physics, 2008) Dumuid, P.; Cazzolato, B.; Zander, A.The application of inverse filter designs as a means of providing improved communication performance in acoustic environments is investigated. Tikhonov regularized inverse filters of channel transfer functions calculated in the frequency domain are used as a means of obtaining multi-channel filters. Three classifications of inverse filter structures have been considered using time-domain simulations. The performance of Tikhonov regularized inverse filters designed according to each of these classifications is compared with each other and against a filter design developed by Stojanovic [Stojanovic, M. (2005). "Retrofocusing techniques for high rate acoustic communications," J. Acoust. Soc. Am. 117, 1173-1185]. It is shown that the filter design developed by Stojanovic requires less regularization and outperforms the Tikhonov regularized inverse filter designs when communicating over a single channel. While the filter developed by Stojanovic is designed to use multiple transmitters to transmit to a single receiver, the filter was implemented in a multi-channel system and proposed to have a focusing similar to that obtained using time-reversal. It was found that for the scenario used in the simulation, the Tikhonov regularized inverse design for full multi-channel inversion achieved better focusing than the design by Stojanovic, where simulation results show 20 dB less cross-talk at the expense of around 2 dB loss in signal strength.