School of Mechanical Engineering

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https://hdl.handle.net/2440/294

The School of Mechanical Engineering conducts research in a diverse and wide range of areas. Major areas of interest include the following:

Acoustic, Vibration and Control
Air Conditioning
Tubulence, Energy and Combustion
CRC for Welded Structures
Robotics

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School of Mechanical Engineering
THE UNIVERSITY OF ADELAIDE
SA 5005
AUSTRALIA

Telephone: +61 8 8313 5460
Facsimile: +61 8 8313 4367

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Now showing 1 - 20 of 2972

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14th Australasian Fluid Mechanics Conference - Preface
(Elsevier Science Inc, 2003) Dally, B.; Kelso, R.; Nathan, G.; Denier, J.
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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.
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2D Shaped sensors for feedback control
(2001) Kidner, M.; Johnson, M.; International Congress and Exhibition on Noise Control Engineering (2001 : Hague, Netherlands)
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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.
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3D stockpile modelling and quality calculation for continuous stockpile management
(Elservier Science BV, 2015) Zhao, S.; Lu, T.; Koch, B.; Hurdsman, A.
Abstract not available
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3D stockpile modelling to improve the quality control in iron ore handling
(Avestia, 2014) Zhao, S.; Lu, TF, D.; Koch, B.; Hurdsman, A.; 1st International Conference on Mining, Material and Metallurgical Engineering (MMME'14) (11 Aug 2014 - 12 Aug 2014 : Prague, Czech Republic)
This paper describes a 3D stockpile modelling algorithm to improve quality control and increase operational efficiency in iron ore handling. The 3D model, generated from real measuring data, approximates a stockpile using a group of 3D volumetric element, which able to store information inside it, such as quality compositions of the ore. By associating this model with the cutting geometry of a real reclaimer, the quality of reclaimed material can be calculated and it is then possible to adjust the reclaiming according to the end objective with an optimised and continuous machine movement. This will help convert the current reactive and discontinuous reclaiming procedure into a proactive and unbroken mode. The proposed modelling algorithm was tested on a scaled down stockpile model and results demonstrate good, precise and fast performances.
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4+1>3+2?
(AAEE, 2009) Kestell, C.; Arjomandi, M.; Dally, B.; Grainger, S.; Blazewicz, A.; Australasian Association for Engineering Education Conference (20th : 2009 : Adelaide, South Australia)
The focus of engineering education has dramatically changed in Europe as a direct result of the Bologna process. While the intention of this was to create a more uniform educational system, another outcome has been that professional engineers are now expected to graduate with a Masters Degree rather than a Bachelors Degree. The University of Melbourne has been the first Australian university to proactively approach this issue by introducing the Melbourne Model, which comprises of a three (not four!) year Bachelors Degree (not a BEng!) followed by a two year Masters Degree (3+2). In an environment conditioned to focus on the quality of undergraduate programs, one initial reaction might be that the degree has been watered down. However, this is far from the case because the emphasis is clearly on the students completing five years of study in total. Melbourne University has in fact raised the bar. Never-the-less, their decision to proceed along this pathway has been perceived as risky and expensive, with few Australian universities following as a result. However, there is a real need to refocus on Masters Programs if our graduating students are to be formally recognised globally as world leaders in their professional capacity. The Faculty of Engineering Computing and Mathematical Sciences (ECMS) at the University of Adelaide will therefore introduce an alternative pathway to Masters in 2010, requiring only one additional year of study upon the successful completion of a four-year Bachelor of Engineering degree. This paper is very much a show and tell work in progress, with only very early indicators of the program’s potential success. While it is believed that there are a number of advantages to the Adelaide Four plus One Model, these are not presented as a better option, but simply as an option. Four plus one programs may be perceived as a long-term solution, or even a transitional solution towards a three plus two. Regardless of the preferred pathway, Australian Universities must now prepare for the obviously imminent refocusing of our educational system towards Masters Programs.
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6 degrees of freedom (DOF) maritime robotic simulation framework
(IEEE, 2010) Tan, K.; Anvar, A.; Lu, T.; International Conference on Control, Automation, Robotics and Vision (2010 : Singapore)
Testing and gauging Autonomous Underwater Vehicle (AUV) missions through observations and experimental trials prove to be time consuming and costly. A system capable of verifying the AUV control models prior to practical test is needed. One of the key aspects in the presented framework is AUV modeling which mainly covers the area of AUV dynamics. Based on this designed simulation framework, custom scenarios provided by the user can be modeled and its corresponding 6DOF dynamics can be observed. The simulation framework is built based on a developed AUV test-bed which was jointly upgraded by DSTO and the University of Adelaide.
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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.
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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.
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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.
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 available
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 available
Restricted
A biologically inspired facilitation mechanism enhances the detection and pursuit of targets of varying contrast
(IEEE, 2014) Bagheri, Z.; Wiederman, S.; Cazzolato, B.; Grainger, S.; O'Carroll, D.; 16th International Conference on Digital Image Computing: Techniques and Applications (DICTA) (25 Nov 2014 - 27 Nov 2014 : Wollongong, NSW)
Many species of flying insects detect and chase prey or conspecifics within a visually cluttered surround, e.g. for predation, territorial or mating behavior. We modeled such detection and pursuit for small moving targets, and tested it within a closed-loop, virtual reality flight arena. Our model is inspired directly by electrophysiological recordings from ‘small target motion detector’ (STMD) neurons in the insect brain that are likely to underlie this behavioral task. The front-end uses a variant of a biologically inspired ‘elementary’ small target motion detector (ESTMD), elaborated to detect targets in natural scenes of both contrast polarities (i.e. both dark and light targets). We also include an additional model for the recently identified physiological ‘facilitation’ mechanism believed to form the basis for selective attention in insect STMDs, and quantify the improvement this provides for pursuit success and target discriminability over a range of target contrasts.
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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.
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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.
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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.
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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.
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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.
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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 available

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