Abbasi, WS, Shams-Ul-Islam, Saha, SC, Gu, YT & Ying, ZC 2014, 'Effect of Reynolds numbers on flow past four square cylinders in an in-line square configuration for different gap spacings', Journal of Mechanical Science and Technology, vol. 28, no. 2, pp. 539-552.
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Aljabri, A, Jiang, ZY & Wei, DB 2014, 'Analysis of Thin Strip Profile during Asymmetrical Cold Rolling with Roll Crossing and Shifting Mill', Advanced Materials Research, vol. 894, pp. 212-216.
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Strip profile control during rolling is required to assure the dimensional quality of rolled thin strip is acceptable for customers. Throughout rolling, the strip profile is controlled by using the advanced shape control rolling mill, such as the combination of work roll crossing and shifting during asymmetrical rolling, the one of the valuable methods to control the strip profile quality in rolling process. In this paper, the influences of cold rolling parameters such as the crossing angle and axial shifting value of work rolls on the strip profile are analysed. The strip shape control is discussed under both symmetrical and asymmetrical rolling conditions. The obtained results are appropriate to control the rolled thin strip profile in practice.
Aljabri, A, Jiang, ZY, Wei, DB, Wang, XD & Tibar, H 2014, 'Thin Strip Profile Control Capability of Roll Crossing and Shifting in Cold Rolling Mill', Materials Science Forum, vol. 773-774, pp. 70-78.
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Controlling cold strip profile is a difficult and significant problem has been found in industry during thin strip rolling. At present choosing the new type of strip rolling mill is the one of main methods to control the strip shape quality in cold rolling. The influences of rolling process parameters such as the work roll cross angle and work roll shifting on the strip shape and profile of thin strip are recognised throughout this study. The results show that the roll crossing and shifting is efficient way to control the strip shape. The increase of the work roll crossing angle would lead to improve the strip profile significantly by decreasing the exit strip crown and edge drop. The strip profile would be enhanced if the axial roll shifting was increased. Moreover, the total rolling force was analysed in detail by changing the roll cross angle and axial shifting roll.
Alzanki, T, Bennett, N, Gwilliam, R, Jeynes, C, Bailey, P, Noakes, T & Sealy, B 2014, 'Ion Beam Analysis for Hall Scattering Factor Measurements in Antimony Implanted Bulk and Strained Silicon', JOURNAL OF ENGINEERING RESEARCH, vol. 2, no. 1, pp. 121-132.
Al-Zubaydi, AYT & Dartnall, WJ 2014, 'Design and Modelling of Water Chilling Production System by the Combined Effects of Evaporation and Night Sky Radiation', Journal of Renewable Energy, vol. 2014, pp. 1-8.
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The design and mathematical modelling of thermal radiator panel to be used primarily to measure night sky radiation wet coated surface is presented in this paper. The panel consists of an upper dry surface coated aluminium sheet laminated to an ethylene vinyl acetate foam backing block as an insulation. Water is sprayed onto the surface of the panel so that an evaporative cooling effect is gained in addition to the radiation effect; the surface of a panel then is wetted in order to study and measure the night sky radiation from the panel wet surface. In this case, the measuring water is circulated over the upper face of this panel during night time. Initial TRNSYS simulations for the performance of the system are presented and it is planned to use the panel as calibrated instruments for discriminating between the cooling effects of night sky radiation and evaporation.
Banwell, GH, Roberts, JR, Halkon, BJ, Rothberg, SJ & Mohr, S 2014, 'Understanding the Dynamic Behaviour of a Tennis Racket under Play Conditions', Experimental Mechanics, vol. 54, no. 4, pp. 527-537.
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The 'feel' of tennis rackets is of increasing importance to manufacturers seeking product differentiation in a context where further performance enhancements are prevented by a combination of mechanical limits and regulations imposed to protect the integrity of the sport. Vibrations excited during a shot contribute greatly to the perception of 'feel'. Previous studies have been reported but none has covered the full set of mode families or the frequency range in this study. In-plane vibrations associated with the routine use of topspin shots in modern tennis have not been documented so far in the literature. To consider modal behaviour, multiple measurements during play conditions are required but this is practically impossible. This paper proposes an alternative approach and successfully relates a comprehensive modal analysis on a freely suspended racket to vibration measurements under play conditions. This is achieved through an intermediate stage comprising a necessarily more limited modal analysis on a hand-gripped racket and use of the mass modification modal analysis tool. This stage confirmed the prevailing view that hand-gripping can be considered as a mass modification distributed along the handle of the freely suspended racket but the associated mass was much lower than that of an actual hand and the hand also increased the damping ratio of frame modes significantly. Furthermore, in frame vibration measurements during forehand groundstrokes, a greater reduction in bending mode frequencies was observed, consistent with a mass-loading of around 25 % of the actual hand as a consequence of the tighter grip. In these play tests, the first two bending modes, the first torsional mode, the first eight stringbed modes, the first three hoop modes and the third in-plane bending mode were identified, with the stringbed modes being particularly prominent. © 2013 Society for Experimental Mechanics.
Bhowmick, S, Molla, MM, Mia, M & Saha, SC 2014, 'Non-newtonian Mixed Convection Flow from a Horizontal Circular Cylinder with Uniform Surface Heat Flux', Procedia Engineering, vol. 90, pp. 510-516.
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Blamires, SJ, Hou, C, Chen, L-F, Liao, C-P & Tso, I-M 2014, 'A predator’s body coloration enhances its foraging profitability by day and night', Behavioral Ecology and Sociobiology, vol. 68, no. 8, pp. 1253-1260.
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Brunner, N, Fallböhmer, M, Sousanabady, RJ, Schallow, J & Deuse, J 2014, 'Plattformkonzept für die Montageplanung', Zeitschrift für wirtschaftlichen Fabrikbetrieb, vol. 109, no. 11, pp. 848-852.
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Kurzfassung Die Standardisierung von Montagesystemen stellt eine Möglichkeit dar, die Wettbewerbsfähigkeit produzierender Unternehmen zu sichern. Durch die Wiederverwendung bekannter Systemelemente wird zum einen die Planungszeit verkürzt, zum anderen die Qualität des Ergebnisses gesteigert. Damit die Standards in globalen Planungsnetzwerken angewendet werden können, ist die Unterstützung durch digitale Werkzeuge erforderlich. In diesem Beitrag wird ein Referenzdatenmodell für die digitale Abbildung eines standardisierten Montagesystems sowie die Umsetzung in einem PLM-System beschrieben.
Cagno, E & Trianni, A 2014, 'Evaluating the barriers to specific industrial energy efficiency measures: an exploratory study in small and medium-sized enterprises', Journal of Cleaner Production, vol. 82, pp. 70-83.
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Cai, B, Huang, S, Liu, D & Dissanayake, G 2014, 'Rescheduling policies for large-scale task allocation of autonomous straddle carriers under uncertainty at automated container terminals', ROBOTICS AND AUTONOMOUS SYSTEMS, vol. 62, no. 4, pp. 506-514.
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This paper investigates replanning strategies for container-transportation task allocation of autonomous Straddle Carriers (SC) at automated container terminals. The strategies address the problem of large-scale scheduling in the context of uncertainty (especially uncertainty associated with unexpected events such as the arrival of a new task). Two rescheduling policies-Rescheduling New arrival Jobs (RNJ) policy and Rescheduling Combination of new and unexecuted Jobs (RCJ) policy-are presented and compared for long-term Autonomous SC Scheduling (ASCS) under the uncertainty of new job arrival. The long-term performance of the two rescheduling policies is evaluated using a multi-objective cost function (i.e., the sum of the costs of SC travelling, SC waiting, and delay of finishing high-priority jobs). This evaluation is conducted based on two different ASCS solving algorithms-an exact algorithm (i.e., branch-and-bound with column generation (BBCG) algorithm) and an approximate algorithm (i.e., auction algorithm)-to get the schedule of each short-term planning for the policy. Based on the map of an actual fully-automated container terminal, simulation and comparative results demonstrate the quality advantage of the RCJ policy compared with the RNJ policy for task allocation of autonomous straddle carriers under uncertainty. Long-term testing results also show that although the auction algorithm is much more efficient than the BBCG algorithm for practical applications, it is not effective enough, even when employed by the superior RCJ policy, to achieve high-quality scheduling of autonomous SCs at the container terminals. © 2013 Elsevier B.V. All rights reserved.
Cheng, X, Jiang, Z & Wei, D 2014, 'Effects of oxide scale on hot rolling of an austenitic stainless steel', International Journal of Surface Science and Engineering, vol. 8, no. 2/3, pp. 173-173.
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Cheng, X, Jiang, Z, Wei, D, Zhao, J, Monaghan, BJ, Longbottom, RJ & Jiang, L 2014, 'Characteristics of oxide scale formed on ferritic stainless steels in simulated reheating atmosphere', Surface and Coatings Technology, vol. 258, pp. 257-267.
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© 2014 Elsevier B.V. The aim of this study is to optimise the stainless steel oxidation behaviours during hot rolling. The high temperature oxidation behaviours of ferritic stainless steels B443NT and B445J1M were studied over the temperature range from 1000 to 1150°C in a humid atmosphere containing 18% water vapour, as measured by a thermogravimetric analyser (TGA). The results indicate that breakaway oxidation occurs at 1090°C for the B443NT steel, which is 60°C lower than that for the B445J1M steel. The occurrence of iron oxide nodules on the steels marks the onset of breakaway oxidation; however, the breakaway oxidation phenomenon of B445J1M is different from that of B443NT due to a compact and continuous Mn-Cr spinel which is formed on the surface of B445J1M. The oxide nodules with regenerated Cr 2 O 3 scale underneath the Fe-Cr spinel display better adhesion without showing pores at the metal-scale interface.
Cheng, XW, Jiang, ZY, Luo, GZ, Wei, DB & Hao, L 2014, 'Study on Oxidation Behavior of Stainless Steels in Short Time', Applied Mechanics and Materials, vol. 633-634, pp. 209-214.
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The various chemical compositions of stainless steels can result in complication of the formation of oxide scales in hot rolling process. The time for formation of tertiary oxide scale during finishing rolling is short. In the present study, the oxidation tests with short time period were carried out on eight stainless steel grades by Gleeble 3500 thermal mechanical simulator in a simulated water mist environment. Multi-layers of oxide scale have been developed on all the steel grades during short time oxidation. Internal and intergranular oxides were formed in the steel matrix underneath the inner spinel oxide layer. The cross section of the oxide scales were examined and measured by SEM to understand the oxide scale cross section morphology and thickness.
Fang, Z, Jiang, ZY & Wei, DB 2014, 'Modeling of Grained Heterogeneity with Voronoi Tessellation in Microforming Process', Applied Mechanics and Materials, vol. 553, pp. 66-70.
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Microforming technology has attracted more and more attention because of its high utilization in almost every field. However, due to size effect, the conventional scale mechanical processing theories could not be applicable. Further, the characteristic of each single grain involved in the deformed area activates to play a significant role in the manufacturing process. In order to reflect and investigate the relationship among these grains better, this paper represents a pre-process modeling method with Voronoi tessellation to reveal the grained heterogeneity of workpiece numerically in order to obtain high accuracy and prediction result in finite element (FE) modelling of microforming process. Corresponding micro V-bending experiments have been carried out, and the experimental results are in good agreement with simulation results in terms of final angles after micro bending with consideration of springback.
Fang, Z, Lu, H, Wei, D, Jiang, Z, Zhao, X, Zhang, X & Wu, D 2014, 'Numerical Study on Springback with Size Effect in Micro V-bending', Procedia Engineering, vol. 81, pp. 1011-1016.
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With the development of microforming technology, the demand on accuracy of the metallic micro components is elevating. While springback phenomenon which is inevitable during bending process, can cause unpredicted dimensional error, bringing difficulties to the downstream assembly, and let alone the springback in microforming as the measurements of tools and workpieces downsize hundreds even thousands times. This paper focuses on the springback effect that occurs after the micro V-bending a classic processing method to manufacture microparts. Numerical simulation has been conducted to investigate the size effect in terms of Voronoi tessellation and springback. A finite element (FE) model of the micro V-bending has been established by utilising ABAQUS/Standard commercial software. The grain sizes of 98, 152 and 201 μm have been adopted in FE model to study the relationship between the size effect and springback angle during the V-bending process.
Gao, X, Jiang, Z, Wei, D, Jiao, S, Chen, D, Xu, J, Zhang, X & Gong, D 2014, 'Effects of temperature and strain rate on microstructure and mechanical properties of high chromium cast iron/low carbon steel bimetal prepared by hot diffusion-compression bonding', Materials & Design, vol. 63, pp. 650-657.
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© 2014 Elsevier Ltd. The objective of this study is to develop a hot diffusion-compression bonding process for cladding low carbon steel (LCS) to high chromium cast iron (HCCI) in solid-state. The influence of temperature (950-1150°C) and strain rate (0.001-1s-1) on microstructure, hardness and bond strength of the HCCI/LCS bimetal were investigated. The interface microstructure reveals that the unbonded region can only be found for 950°C due to lack of diffusion, while the intergrowth between the constituent metals occurred at and above 1100°C. When bonding temperature increases to 1150°C, a carbide-free zone was observed near the interface on the HCCI layer, and the thickness of the zone decreases with an increase of bonding strain rate. These evolutions indicate that the bond quality was improved by raising temperature and reducing strain rate due to the increase of element diffusion. The hot compression process of the bonding treatment not only changes the carbide orientation of the HCCI, but also increases the volume fraction of Cr-carbide. Based on the microstructural examinations and mechanical tests, the optimum bonding temperature and bonding strain rate are determined to be 1150°C and 0.001s-1, respectively.
Gao, XJ, Jiang, ZY, Wei, DB, Jiao, SH & Chen, DF 2014, 'Study on Hot-Working Behavior of High Carbon Steel / Low Carbon Steel Composite Material Using Processing Map', Key Engineering Materials, vol. 622-623, pp. 330-339.
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The high carbon steel (HCS)/low carbon steel (LCS) laminated composite made by centrifugal casting technology was subjected to hot compression tests on Gleeble 3500 thermomechanical simulator in a range of temperatures (800-1100oC) and strain rates (0.02-10 s-1). The hot-working behavior of the laminate was characterised by analysing the flow stress-strain curves and constructing the processing map based on dynamic materials model via superimposing efficiency of power dissipation and flow instability maps. The safe and unsafe processing conditions were identified in the processing map which was validated by microstructural examinations. Banded microstructure and micro-shear cracks occurred in the unsafe domains were responsible for the flow instability, while dynamic recrystallisation in stable domains with high efficiency of power dissipation imparted a good workability to the laminate. The optimum hot-working parameters were determined to be: (i) 800-1050oC and 0.02-0.04 s-1, (ii) 800-1045oC and 2.5-10 s-1and (iii) 1050-1100oC and 0.02-2.5 s-1.
Gao, XJ, Jiang, ZY, Wei, DB, Jiao, SH & Han, JT 2014, 'Computational Analysis of Compressive Strain Hardening Exponents of Bimetal with Pearlitic Steel and Low Carbon Steel', Applied Mechanics and Materials, vol. 553, pp. 71-75.
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The compressive strain hardening behaviour of a novel bimetal with pearlitic steel and low carbon steel was investigated by computational analysis based on the isothermal compression tests in a wide range of deformation temperature and strain rate. The Hollomon’s equation was employed to calculate the strain hardening exponent (SHE) with the assistance of mathematical manipulation. The result shows that the logarithmic relationship between the flow stress and plastic strain of the bimetal is highly non-linear, which results in the variation of the SHE of the bimetal. This variation reflects the dynamic competition between the strain hardening and softening mechanism by the varying value of the SHE in the range of 0.4 to-0.4. Furthermore, the influences of deformation temperature and strain rate on the SHE are significant. With decreasing temperature and increasing strain rate, the strain hardening of the bimetal was enhanced, while the dynamic recrystallisation was activated under the opposite conditions with the evidence of negative SHE value.
Gao, XJ, Jiang, ZY, Wei, DB, Kosasih, BY, Jiao, SH & Chen, DF 2014, 'Dry Sliding Wear Behaviour of Full Pearlite Obtained by Cladding Low Carbon Steel to Hypoeutectoid Steel', Advanced Materials Research, vol. 1017, pp. 147-153.
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The dry sliding wear behaviour of the full pearlite in a novel bimetal consisting of low carbon steel and hypoeutectoid steel has been studied by means of pin-on-disc type wear tests at room temperature. Thermomechanical treatments were performed on the bimetallic samples to obtain different interlamellar spacings. It was found that interlamellar spacing decreased with an increase in plastic strain to a great extent initially and followed by a lower extent of decrease. This decrease not only increases the hardness and strain hardening capacity of the fully pearlitic microstructure, but also is in favor of stabilizing the friction coefficient during sliding process. The observations of wear tracks show that delamination dominated the wear process when interlamellar spacing is higher than 200 nm, while pronounced oxidational wear occurred with interlamellar spacing below 200 nm.
Gao, XJ, Jiang, ZY, Wei, DB, Li, HJ, Jiao, SH & Han, JT 2014, 'Effects of Thermomechanical Treatments on Microstructure and Mechanical Behavior of HCS/LCS Bimetal', Advanced Materials Research, vol. 922, pp. 183-188.
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A high carbon steel (HCS) and low carbon steel (LCS) bimetal was fabricated by centrifugal composite casting. Two different thermomechanical treatments (TMT1 and TMT2) were employed to improve the mechanical properties of the bimetal. TMT1 process includes 60% of overall reduction by hot compression with temperatures of 1100 and 800 oC, respectively. While TMT2 process involves 60% of overall reduction using the two-step deformation method, which is a combination of non-isothermal compression cooling from 1100 to 800 oC and isothermal compression at 800 oC. The flow stress behavior, microstructural evolution and microhardness variation were analysed. Experimental results show that both TMT processes contributed to the improvement in mechanical properties resulting from a refinement of the grain size and an increase of density of pearlitic lamella in HCS layer. However, TMT2 process gave a better efficiency and a more significance in improvement of properties with the evidence of the same overall reduction leading to a higher microhardness.
Gao, XJ, Jiang, ZY, Wei, DB, Li, HJ, Jiao, SH, Xu, J, Zhang, XM, Han, JT & Chen, DF 2014, 'Constitutive analysis for hot deformation behaviour of novel bimetal consisting of pearlitic steel and low carbon steel', Materials Science and Engineering: A, vol. 595, pp. 1-9.
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To understand the high temperature flow behaviour of a novel pearlitic steel (PS) and low carbon steel (LCS) bimetal, hot compression tests in a wide range of temperature and strain rate were conducted on a Gleeble 3500 thermo mechanical simulator, and the constitutive model was developed based on the experimental data. The measured true stress-strain curves exhibited three types of variation patterns, which are (i) a plateau type, (ii) single peak type and (iii) multi peaks type. These patterns well displayed the effects of the deformation temperature, strain rate and plastic strain on the flow behaviour of the bimetal. By incorporating the Zener-Hollomon parameter and material parameter functions of α(ε), n(ε), Q(ε) and A(ε) into Arrhenius-type constitutive equation, the flow stress values predicted by the proposed model show a good agreement with experimental results by the evidence of reproducing true stress-strain curves accurately, high value of correlation coefficient (R=0.9873) and low value of average absolute relative error (AARE=4.81%). The proposed constitutive equation can be used to realise numerical simulation and determine processing parameters during hot-working of the PS/LCS bimetal. © 2013 Elsevier B.V.
Guertler, MR 2014, 'How to assess actors for an open: Innovation-project?', Journal of Modern Project Management, vol. 2, no. 2, pp. 56-63.
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Companies are confronted with an increasing variety of challenges such as shortened development cycles or higher demand of market orientation. One potential solution is collaboration with external partners/actors in terms of Open Innovation (OI). This allows several advantages such as the utilization of external expertise and reduced risk of market fails. However, OI itself bears 'new' risks which are often related to the choice of external actors, e.g. insufficient effort-benefit ratio or knowledge drain. So far, adequate methodical support is limited. To allow an efficient identification and selection of actors, established approaches from other fields, such as stakeholder (SH) analysis, are enhanced by OI-specific methods. This paper presents an integrated assessment approach for determining relevant actors within a previously identified pool of SH. The approach combines elements from SH-analysis and Lead-User identification, enhanced by elements from complexity management.
Halkon, BJ & Rothberg, SJ 2014, 'Angular (pitch and yaw) vibration measurements directly from rotors using laser vibrometry', Mechanical Systems and Signal Processing, vol. 46, no. 2, pp. 344-360.
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Parallel beam laser vibrometers offer direct measurement of pitch and yaw vibration directly from rotors. This paper, intended as an essential guide for the practical parallel beam laser vibrometer practioner, presents exact mathematical expressions for measured angular velocity in the presence of inevitable misalignments and estimates the likely measurement error levels due to such misalignments as well as to other sources of uncertainty through numerical simulation. Cross-sensitivity to the orthogonal vibration component, i.e. cross-sensitivity in a pitch measurement to yaw motion and vice-versa, is confirmed for rough rotors whereas it is shown not to be present when rotors are polished-circular. A complementary experimental investigation of the relationship between surface roughness and cross-sensitivity confirms the identification of two preferred measurement configurations: from the side of a polished-circular rotor and from the end face of a (rough) rotor coated in retro-reflective tape. Rotors with surface roughness up to 50 nm satisfy the former case provided the vibration displacement at the rotor surface does not exceed 20% beam diameter. For surfaces with roughness of 10 nm this can be extended to 50%. For rough rotor end face measurements, post-processing is required to resolve the inherent cross-sensitivity; the need for post-processing is justified quantitatively through numerical simulation. Further simulations incorporating typical levels of instrument misalignment and measurement noise are used to enable quantification of the likely errors in such angular vibration measurements. For measurements from the side of a polished-circular rotor, errors are around 1% for amplitude and 10 mrad at integer orders affected by pseudo-vibration and around one-third of these levels elsewhere. For measurements from a rough rotor end face, errors will be similar at integer orders (from 2). Errors in the rotational speed measurement, required for post-p...
Islam, M, Karim, MA, Saha, SC, Miller, S & Yarlagadda, PKDV 2014, 'Development of Empirical Equations for Irradiance Profile of a Standard Parabolic Trough Collector Using Monte Carlo Ray Tracing Technique', Advanced Materials Research, vol. 860-863, pp. 180-190.
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This article explains a technique in which equations are developed to produce the irradiance profile around the receiver of LS2 collector using a vigorouslyverified MCRT model. A large range of test conditions including daily normal insolation, selective coatings and glass envelop conditions were chosen from the published data by Dudley et al. [1] for the job. The R2 value is excellent that varies between 0.9857 and 0.9999. Therefore, these equations can be used confidently to produce boundary heat flux profile of the collector at normal incident for conjugate heat transfer analyses of the receiver.
Ismail, MF, Hasan, MN & Saha, SC 2014, 'Numerical study of turbulent fluid flow and heat transfer in lateral perforated extended surfaces', Energy, vol. 64, pp. 632-639.
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Ji, JC 2014, 'Design of a nonlinear vibration absorber using three-to-one internal resonances', MECHANICAL SYSTEMS AND SIGNAL PROCESSING, vol. 42, no. 1-2, pp. 236-246.
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A weakly nonlinear vibration absorber is designed to attenuate the primary resonance vibrations of a single-degree-of-freedom weakly nonlinear oscillator having cubic nonlinearity. The linearised natural frequency of the nonlinear absorber is tuned to be approximately one-third the linearised natural frequency of the primary nonlinear oscillator. The low frequency mode for the absorber is favourably considered based on the fact that the nonlinear absorber can be easily realised in practice by using a light-weight mass attachment with small values of linear and nonlinear stiffness of coupling. For a given primary nonlinear oscillator and absorber mass, implementation of three-to-one internal resonances requires the smallest value of the absorber linear stiffness among three options for utilising internal resonances to design nonlinear absorber. The method of multiple scales is used to obtain the averaged equations that determine the amplitudes and phases of the first-order approximate solutions to the vibrations of the primary nonlinear oscillator and nonlinear absorber. It is found that the absorber response may admit either forced vibration having the forcing frequency or a combination of forced vibration and free-oscillation term having one third the forcing frequency. The nonlinear absorber can effectively suppress the amplitude of primary resonance response and eliminate saddle-node bifurcations occurring in the frequency-response curves of the primary nonlinear oscillator. Numerical results are given to show the effectiveness of the nonlinear absorber for suppressing nonlinear vibrations of the primary nonlinear oscillator under primary resonance conditions. © 2013 Elsevier Ltd. All rights reserved.
Ji, JC 2014, 'Secondary resonances of a quadratic nonlinear oscillator following two-to-one resonant Hopf bifurcations', NONLINEAR DYNAMICS, vol. 78, no. 3, pp. 2161-2184.
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© 2014, Springer Science+Business Media Dordrecht. Stable bifurcating solutions may appear in an autonomous time-delayed nonlinear oscillator having quadratic nonlinearity after the trivial equilibrium loses its stability via two-to-one resonant Hopf bifurcations. For the corresponding non-autonomous time-delayed nonlinear oscillator, the dynamic interactions between the periodic excitation and the stable bifurcating solutions can induce resonant behaviour in the forced response when the forcing frequency and the frequencies of Hopf bifurcations satisfy certain relationships. Under hard excitations, the forced response of the time-delayed nonlinear oscillator can exhibit three types of secondary resonances, which are super-harmonic resonance at half the lower Hopf bifurcation frequency, sub-harmonic resonance at two times the higher Hopf bifurcation frequency and additive resonance at the sum of two Hopf bifurcation frequencies. With the help of centre manifold theorem and the method of multiple scales, the secondary resonance response of the time-delayed nonlinear oscillator following two-to-one resonant Hopf bifurcations is studied based on a set of four averaged equations for the amplitudes and phases of the free-oscillation terms, which are obtained from the reduced four-dimensional ordinary differential equations for the flow on the centre manifold. The first-order approximate solutions and the nonlinear algebraic equations for the amplitudes and phases of the free-oscillation terms in the steady state solutions are derived for three secondary resonances. Frequency-response curves, time trajectories, phase portraits and Poincare sections are numerically obtained to show the secondary resonance response. Analytical results are found to be in good agreement with those of direct numerical integrations.
Jiang, Z, Lu, H, Wei, D, Linghu, KZ, Zhao, X, Zhang, X & Wu, D 2014, 'Finite Element Method Analysis of Micro Cross Wedge Rolling of Metals', Procedia Engineering, vol. 81, pp. 2463-2468.
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A newly developed manufacturing technology - micro cross wedge rolling technology is an appropriate method to produce micro axisymmetric components such as micro stepped shafts. The development of this classic cold forming process is limited by a lack of sufficient understanding of geometric and material effects due to the size reduction of the components. In this study, a numerical model is proposed to simulate micro cross wedge rolling where the grain size effect is taken into account. Pure copper is chosen as the raw material. A finite element simulation is implemented where the diameter of the cylindrical workpiece is 0.8 mm and the polycrystalline aggregates are represented by Voronoi tessellation. The mean grain sizes of these workpiece range from 6 to 248 μm, in order to evaluate the grain size effect on the material flow. Meanwhile, a set of experiments are performed on the workpieces that have been heat treated. The experimental results show a good agreement with the simulation results by comparing the rolling forces and evolution of microstructures.
Jiang, ZY, Wei, DB, Cheng, XW, Gao, X, Zhang, JW, Huang, JX, Zhang, AW, Shi, X & Jiao, SH 2014, 'Surface Roughness and Friction in Hot Rolling of Stainless Steels', Materials Science Forum, vol. 783-786, pp. 795-800.
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An experimental method was developed to examine oxidations of austenitic and martensitic stainless steels. The results show that the surface roughness along both rolling and transverse directions decreases with an increase of reduction. When the reheating time is increased, the average thickness of oxide scales of stainless steels increases, which results in relatively rough surface after hot rolling. The effects of oxide scale on the friction condition and surface roughness transfer in hot rolling depend on the oxide scale generated during reheating. The calculated surface roughness is close to the experimental results, which verifies the developed FEM model.
Karvinen, KS, Ruppert, MG, Mahata, K & Moheimani, SOR 2014, 'Direct Tip-Sample Force Estimation for High-Speed Dynamic Mode Atomic Force Microscopy', IEEE Transactions on Nanotechnology, vol. 13, no. 6, pp. 1257-1265.
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Kehrel, U & Sick, N 2014, 'Economic and technological forecasting competencies of German energy companies', International Journal of Energy Sector Management, vol. 8, no. 4, pp. 588-610.
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Purpose – This paper aims to extend the small body of literature on energy industry transitions on firm level. A growing number of articles shed light on paradigm shifts in the energy industry and the influence of renewable energies on industry structures. In the majority of cases, the authors analyze changes on a global or national level. Design/methodology/approach – Energy companies’ forecasting capabilities are particularly important to enable them to react in time to upcoming changes in industry structures. In this context, we analyze annual reports of German energy companies to evaluate their economic and technological forecasting competencies. Findings – Big energy providers offer high economic forecasting quality, but seem to be less able to derive valid forecasts in terms of renewable energies from the currently unstable political frameworks. On the contrary, renewable energy companies do not seem to suffer from these difficulties and provide good foresting accuracy in terms of renewable energy development, but show less accurate economic forecasting quality. Practical implications – Big energy providers need to find the means of responding to the challenges and integrate changing political guidelines and support into their forecasting system. Renewable energy companies, in contrast, should focus on company-level profitability and the respective economic forecasting competencies. ...
Khushaba, RN, Takruri, M, Miro, JV & Kodagoda, S 2014, 'Towards limb position invariant myoelectric pattern recognition using time-dependent spectral features', NEURAL NETWORKS, vol. 55, pp. 42-58.
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Recent studies in Electromyogram (EMG) pattern recognition reveal a gap between research findings and a viable clinical implementation of myoelectric control strategies. One of the important factors contributing to the limited performance of such controllers in practice is the variation in the limb position associated with normal use as it results in different EMG patterns for the same movements when carried out at different positions. However, the end goal of the myoelectric control scheme is to allow amputees to control their prosthetics in an intuitive and accurate manner regardless of the limb position at which the movement is initiated. In an attempt to reduce the impact of limb position on EMG pattern recognition, this paper proposes a new feature extraction method that extracts a set of power spectrum characteristics directly from the time-domain. The end goal is to form a set of features invariant to limb position. Specifically, the proposed method estimates the spectral moments, spectral sparsity, spectral flux, irregularity factor, and signals power spectrum correlation. This is achieved through using Fourier transform properties to form invariants to amplification, translation and signal scaling, providing an efficient and accurate representation of the underlying EMG activity. Additionally, due to the inherent temporal structure of the EMG signal, the proposed method is applied on the global segments of EMG data as well as the sliced segments using multiple overlapped windows. The performance of the proposed features is tested on EMG data collected from eleven subjects, while implementing eight classes of movements, each at five different limb positions. Practical results indicate that the proposed feature set can achieve significant reduction in classification error rates, in comparison to other methods, with ≈8% error on average across all subjects and limb positions. A real-time implementation and demonstration is also provided and made a...
Kirby, R, Amott, K, Williams, PT & Duan, W 2014, 'On the acoustic performance of rectangular splitter silencers in the presence of mean flow', Journal of Sound and Vibration, vol. 333, no. 24, pp. 6295-6311.
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© 2014 Elsevier Ltd. Dissipative splitter silencers are often used to reduce the noise emitted in ventilation and gas turbine systems. It is well known that the acoustic performance of a splitter silencer changes under the influence of the convective effects of a mean gas flow and so in this article a theoretical model is developed to include the effects of mean flow. The theoretical model is based on a hybrid finite element method which enables the inclusion of bull nose fairings and a perforated screen separating the mean gas flow from a bulk reacting porous material. Predictions are compared against experimental measurements obtained both with and without mean flow. Good agreement between prediction and measurement is generally observed in the absence of mean flow, although it is seen that for silencers with a low percentage open area the silencer insertion loss is over predicted at higher frequencies. When mean flow is present, problems with the experimental methodology are observed at relatively modest mean flow velocities, and so comparison between prediction and experiment is limited to relatively low face velocities. However, experiment and theory both show that the insertion loss reduces at low frequencies when mean flow is in the direction of sound propagation, and at high frequencies the influence of mean flow is generally much smaller. Following additional theoretical investigations it is concluded that the influence of mean flow on splitter silencer performance should be accounted for at low frequencies when silencer airway velocities are greater than about 20 m/s; however, at higher frequencies one may generally neglect the effect of mean flow, even at higher velocities. Predictions obtained using the hybrid method are also compared to a simplified point collocation approach and it is demonstrated that the computationally efficient point collocation method may be used to investigate the effects of mean flow in a splitter silencer without l...
Kirby, R, Williams, PT & Hill, J 2014, 'A three dimensional investigation into the acoustic performance of dissipative splitter silencers', The Journal of the Acoustical Society of America, vol. 135, no. 5, pp. 2727-2737.
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Splitter silencers are found in ventilation and gas turbine systems and consist of parallel baffles of porous material placed within a duct so that they split the mean gas flow. Theoretical investigations into dissipative splitter silencers have generally been limited to two dimensions and this limits the analysis to finding the silencer eigenmodes or, for a finite length silencer, to rectangular baffles only. In this article a numerical point collocation approach is used to extend theoretical predictions to three dimensions. This facilitates the analysis of more complex silencer designs such as “bar” silencers and theoretical predictions are validated by comparison with experimental measurements. The insertion loss of different silencer designs is evaluated and the performance of a bar silencer is compared to traditional designs for rectangular and circular ducts. It is shown that a bar silencer with a volume of material identical to an equivalent parallel baffle design delivers a significant improvement in insertion loss at higher frequencies, although this is at the expense of a small reduction in performance at low frequencies. It is also shown that under most circumstances it is possible to get good agreement between prediction and experiment even for relatively large Helmholtz numbers.
Kodagoda, S & Sehestedt, S 2014, 'Simultaneous people tracking and motion pattern learning', Expert Systems with Applications, vol. 41, no. 16, pp. 7272-7280.
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The field of Human Robot Interaction (HRI) encompasses many difficult challenges as robots need a better understanding of human actions. Human detection and tracking play a major role in such scenarios. One of the main challenges is to track them with long term occlusions due to agile nature of human navigation. However, in general humans do not make random movements. They tend to follow common motion patterns depending on their intentions and environmental/physical constraints. Therefore, knowledge of such common motion patterns could allow a robotic device to robustly track people even with long term occlusions. On the other hand, once a robust tracking is achieved, they can be used to enhance common motion pattern models allowing robots to adapt to new motion patterns that could appear in the environment. Therefore, this paper proposes to learn human motion patterns based on Sampled Hidden Markov Model (SHMM) and simultaneously track people using a particle filter tracker. The proposed simultaneous people tracking and human motion pattern learning has not only improved the tracking robustness compared to more conservative approaches, it has also proven robustness to prolonged occlusions and maintaining identity. Furthermore, the integration of people tracking and on-line SHMM learning have led to improved learning performance. These claims are supported by real world experiments carried out on a robot with suite of sensors including a laser range finder.
Kuhlang, P, Erohin, O, Krebs, M, Deuse, J & Sihn, W 2014, 'Morphology of time data management - systematic design of time data management processes as fundamental challenge in industrial engineering', International Journal of Industrial and Systems Engineering, vol. 16, no. 4, pp. 415-415.
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During the last 10 to 15 years, a renaissance of industrial engineering can be observed in manufacturing industry, as well as in scientific research. As a consequence, time and motion studies (TMS) become more important again. During the downturn of methodical approaches in industrial engineering in the 1980s, TMS-related competencies were lost in industry. Many companies are still missing the know-how for establishing a proper time data management (TDM). This paper presents a morphology of time data management (MoTDM), which was developed in order to create a comprehensive view on the processes of TDM as well as to detect relevant areas of improvement. The MoTDM can be used to optimise TDM processes within a company and also acts as scientific fundament for research in the field of industrial engineering.Copyright © 2014 Inderscience Enterprises Ltd.
Kyzar, KB, Chiu, C, Kemp, P, Aldersey, HM, Turnbull, AP & Lindeman, DP 2014, 'Feasibility of an Online Professional Development Program for Early Intervention Practitioners', Infants & Young Children, vol. 27, no. 2, pp. 174-191.
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Lecou, C, Sick, N & Leker, J 2014, 'Selection patterns in front-end decision making - determining the probability of idea progress within the internal innovation process', International Journal of Technology Marketing, vol. 9, no. 2, pp. 101-101.
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Li, H, Jiang, Z, Wei, D & Gao, X 2014, 'Influence of Friction on Surface Asperity Flattening Process in Cold Uniaxial Planar Compression (CUPC)', Tribology Letters, vol. 53, no. 2, pp. 383-393.
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Atomic force microscope and electron back-scattering diffraction measurement methods were used to study the effects of friction on surface asperity flattening and surface texture during the uniaxial planar compression of annealed aluminum alloy. With an increase in gauged reduction, surface asperity tended to be flattened. Friction could boost the surface asperity flattening process by reducing the flow stress in deformation. The development of surface asperity features demonstrated that friction can effectively hinder the development of the Goss orientation component {011} < 100 > and clearly promote the generation of brass orientation {011} < 100 > orientation. Regardless of whether the sample was compressed with lubricant or not, a few S orientation component {123} < 634 > formed in sample edge area.
LIM, K-M & RAHNAMA, SS 2014, 'CALCULATION OF ACOUSTIC RADIATION FORCE AND MOMENT IN MICROFLUIDIC DEVICES', International Journal of Modern Physics: Conference Series, vol. 34, pp. 1460380-1460380.
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The ability to compute the acoustic radiation force and torque acting on a particle is critical to the design of microfluidic devices and the operating conditions for separation of different species of particles or biological cells using this force field. Closed-form formulae had been reported in the literature for calculating the acoustic radiation force acting on simple geometries such as spheres and ellipsoids. Also, these analytical formulae are limited to objects that are small compared to the wavelength of sound in the surrounding fluid. Numerical methods provide a more flexible way to calculate the acoustic radiation force and torque on suspended objects of arbitrary shape and size. In this paper, we will present results of using the finite element method and the multipole expansion method to calculate the acoustic radiation force and moment. For harmonic excitation, the Helmholtz equation is solved for the velocity potential of the acoustic field with the appropriate boundary conditions imposed on the surface of the spherical or ellipsoidal objects. The resultant force and torque were then calculated by performing a surface integral of the second order, time-averaged Brillouin stress over the object. The numerical results show good agreement with the analytical results for small size spheres and ellipsoids. When the object size is comparable to the wavelength of the acoustic field, the analytical results breakdown and numerical methods are necessary to obtain accurate results.
Linghu, K, Jiang, Z, Zhao, J, Li, F, Wei, D, Xu, J, Zhang, X & Zhao, X 2014, '3D FEM analysis of strip shape during multi-pass rolling in a 6-high CVC cold rolling mill', The International Journal of Advanced Manufacturing Technology, vol. 74, no. 9-12, pp. 1733-1745.
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© 2014, Springer-Verlag London. A 3D elastic–plastic finite element method (FEM) model of cold strip rolling for 6-high continuous variable crown (CVC) control rolling mill was developed. This model considers the boundary conditions such as accurate CVC curves, total rolling forces, total bending forces and roll shifting values. The rolling force distributions were obtained by the internal iteration processes instead of being treated as model boundary conditions. The calculated error has been significantly reduced by the developed model. Based on the rolling schedule data from a 1,850-mm CVC cold rolling mill, the absolute error between the simulated results and the actual values is obtained to be less than 10 μm and relative error is less than 1 %. The simulated results are in good agreement with the measured data. The developed model is significant in investigating the flatness control capability of the 6-high CVC cold rolling mill in terms of work roll bending forces, intermediate roll bending forces and intermediate roll shifting values.
Lu, HN, Wei, DB & Jiang, ZY 2014, 'Investigation on Dimensional Accuracy in Micro Cross Wedge Rolling of Metals', Key Engineering Materials, vol. 622-623, pp. 943-948.
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A novel microforming process - Micro Cross Wedge Rolling (MCWR) has been developed. It is a very promising technology in the field of microforming due to its advantages such as high product rate and minimised material consumption. How to control geometrical accuracy of the produced micro parts is one of the major challenges in the development of microforming technology. Geometrical accuracy was still concentrated in term of springback. When the wedge tools loads are removed after forming step, a portion of the deformation recovers, which causes a change in the shape of micro parts. In other word, springback happens, which should be determined and controlled especially in microforming technology. A series of MCWR experiments of pure copper and aluminium have been carried out using the machine designed by authors in this study. Cylindrical workpieces were deformed into stepped shafts with cross-sectional area reductions of 35, 52.73 and 75%. Corresponding finite element simulation has also been conducted in consideration of the size effect on the material flow. The springback was proposed to account for the geometrical error of micro products. The effect of grained heterogeneity on the height of surface asperity after rolling was assessed quantitatively.Keywords: Micro cross wedge rolling, Size effect, Dimensional accuracy, Springback
Luo, L, Jiang, Z, Lu, H, Wei, D, Linghu, K, Zhao, X & Wu, D 2014, 'Optimisation of Size-controllable Centroidal Voronoi Tessellation for FEM Simulation of Micro Forming Processes', Procedia Engineering, vol. 81, pp. 2409-2414.
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Voronoi tessellation has been employed to characterise material features in Finite Element Method (FEM) simulation, however, a poor mesh quality of the voronoi tessellations causes problems in explicit dynamic simulation of forming processes. Although centroidal voronoi tessellation can partly improve the mesh quality by homogenisation of voronoi tessellations, small features, such as short edges and small facets, lead to an inferior mesh quality. Further, centroidal voronoi tessellation cannot represent all real micro structures of materials because of the almost equal tessellation shape and size. In this paper, a density function is applied to control the size and distribution of voronoi tessellations and then a Laplacian operator is employed to optimise the centroidal voronoi tessellations. After optimisation, the small features can be eliminated and the elements are quadrilateral in 2D and hexahedral in 3D cases. Moreover, the mesh quality is significantly higher than that of the mesh generated on the original voronoi or centroidal voronoi tessellation. This work is beneficial for explicit dynamic simulation of forming processes, such as micro deep drawing processes.
Luo, L, Jiang, ZY, Wei, DB & He, X 2014, 'Study on Micro Hydroforming of Metals', Advanced Materials Research, vol. 887-888, pp. 1133-1138.
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Micro hydroforming has an ability to manufacture complex 3D micro parts at a high production rate and has drawn increasing attentions. Brief understanding of macro hydroforming, for instance, deep drawing, is necessary to understand the principle of micro hydroforming. Then, special phenomena, such as size effects, occurred at micro scale are discussed and the related theories explaining these phenomena are introduced. Based on the similarities and differences between micro and macro hydroforming, experiments and simulation which consider the size effects are reviewed.
Maschek, T, Heuser, C, Hasselmann, V-R, Deuse, J & Willats, P 2014, 'Variabilitätsbasierte Klassifizierung von Produktionssystemen', Zeitschrift für wirtschaftlichen Fabrikbetrieb, vol. 109, no. 9, pp. 591-594.
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Kurzfassung Ansatzpunkt jeder Verbesserung von Produktionssystemen ist Variabilität. Daher liegt eine Klassifizierung von Produktionssystemen bzgl. ihrer Variabilitätseigenschaften nahe. Die Übertragbarkeit diesbezüglicher Erkenntnisse aus der Erforschung des Toyota Produktionssystems auf Produktionsszenarien ohne Seriencharakter ist jedoch nicht immer gegeben. Dieser Beitrag stellt einen Ansatz zur variabilitätsbasierten Typisierung von Produktionssystemen vor.
Oberst, S, Baro, EN, Lai, JCS & Evans, TA 2014, 'Quantifying Ant Activity Using Vibration Measurements', PLoS ONE, vol. 9, no. 3, pp. e90902-e90902.
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Oberst, S, Evans, TA & Lai, JCS 2014, 'Novel Method for Pairing Wood Samples in Choice Tests', PLoS ONE, vol. 9, no. 2, pp. e88835-e88835.
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Patel, M, Miro, JV, Kragic, D, Ek, CH & Dissanayake, G 2014, 'Learning object, grasping and manipulation activities using hierarchical HMMs', Autonomous Robots, vol. 37, no. 3, pp. 317-331.
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This article presents a probabilistic algorithm for representing and learning complex manipulation activities performed by humans in everyday life. The work builds on the multi-level Hierarchical Hidden Markov Model (HHMM) framework which allows decomposition of longer-term complex manipulation activities into layers of abstraction whereby the building blocks can be represented by simpler action modules called action primitives. This way, human task knowledge can be synthesised in a compact, effective representation suitable, for instance, to be subsequently transferred to a robot for imitation. The main contribution is the use of a robust framework capable of dealing with the uncertainty or incomplete data inherent to these activities, and the ability to represent behaviours at multiple levels of abstraction for enhanced task generalisation. Activity data from 3D video sequencing of human manipulation of different objects handled in everyday life is used for evaluation. A comparison with a mixed generative-discriminative hybrid model HHMM/SVM (support vector machine) is also presented to add rigour in highlighting the benefit of the proposed approach against comparable state of the art techniques. © 2014 Springer Science+Business Media New York.
Perrin, R, Elford, DP, Chalmers, L, Swallowe, GM, Moore, TR, Hamdan, S & Halkon, BJ 2014, 'Normal modes of a small gamelan gong', The Journal of the Acoustical Society of America, vol. 136, no. 4, pp. 1942-1950.
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Studies have been made of the normal modes of a 20.7 cm diameter steel gamelan gong. A finite-element model has been constructed and its predictions for normal modes compared with experimental results obtained using electronic speckle pattern interferometry. Agreement was reasonable in view of the lack of precision in the manufacture of the instrument. The results agree with expectations for an axially symmetric system subject to small symmetry breaking. The extent to which the results obey Chladni's law is discussed. Comparison with vibrational and acoustical spectra enabled the identification of the small number of modes responsible for the sound output when played normally. Evidence of non-linear behavior was found, mainly in the form of subharmonics of true modes. Experiments using scanning laser Doppler vibrometry gave satisfactory agreement with the other methods.
Saha, SC & Gu, YT 2014, 'Transient air flow and heat transfer in a triangular enclosure with a conducting partition', Applied Mathematical Modelling, vol. 38, no. 15-16, pp. 3879-3887.
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Saha, SC, Khan, MMK & Gu, YT 2014, 'Unsteady buoyancy driven flows and heat transfer through coupled thermal boundary layers in a partitioned triangular enclosure', International Journal of Heat and Mass Transfer, vol. 68, pp. 375-382.
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Saha, SC, Lei, C & Patterson, JC 2014, 'Effect of aspect ratio on natural convection in attics subject to periodic thermal forcing', ANZIAM Journal, vol. 49, pp. 677-677.
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© 2007 Austral. Mathematical Soc. We consider the heat transfer through the attics of buildings under realistic (periodic) thermal forcing. The objective of this study is to investigate numerically the effect of the aspect ratio (height to base ratio) on the heat transfer through the attics. A fixed Grashof number 1:33×106 is considered for three different aspect ratios 0.2, 0.5 and 1.0. The Prandtl number is also fixed at 0.71 for air. The details of the numerical model as well as the ow structures and heat transfer data are presented.
Saha, SC, Sauret, E & Gu, YT 2014, 'Magnetic Convection Heat Transfer in an Open Ended Enclosure Filled with Paramagnetic Fluids', Applied Mechanics and Materials, vol. 553, pp. 109-114.
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Numerical simulations of thermomagnetic convection of paramagnetic fluids placed in a micro-gravity condition (g ≈ 0) and under a uniform vertical gradient magnetic field in an open ended square enclosure with ramp heating temperature condition applied on a vertical wall is investigated in this study. In presence of the strong magnetic gradient field thermal convection of the paramagnetic fluid might take place even in a zero-gravity environment as a direct consequence of temperature differences occurring within the fluid. The thermal boundary layer develops adjacent to the hot wall as soon as the ramp temperature condition is applied on it. There are two scenario that can be observed based on the ramp heating time. The steady state of the thermal boundary layer can be reached before the ramp time is finished or vice versa. If the ramp time is larger than the quasi-steady time then the thermal boundary layer is in a quasi-steady mode with convection balancing conduction after the quasi-steady time. Further increase of the heat input simply accelerates the flow to maintain the proper thermal balance. Finally, the boundary layer becomes completely steady state when the ramp time is finished. Effects of magnetic Rayleigh number, Prandtl number and paramagnetic fluid parameter on the flow pattern and heat transfer are presented.
Sahni, V, Miyoshi, T, Chen, K, Jain, D, Blamires, SJ, Blackledge, TA & Dhinojwala, A 2014, 'Direct Solvation of Glycoproteins by Salts in Spider Silk Glues Enhances Adhesion and Helps To Explain the Evolution of Modern Spider Orb Webs', Biomacromolecules, vol. 15, no. 4, pp. 1225-1232.
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Saleem, M, Hossain, MA & Saha, SC 2014, 'Double Diffusive Marangoni Convection Flow of Electrically Conducting Fluid in a Square Cavity With Chemical Reaction', Journal of Heat Transfer, vol. 136, no. 6.
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Double diffusive Marangoni convection flow of viscous incompressible electrically conducting fluid in a square cavity is studied in this paper by taking into consideration of the effect of applied magnetic field in arbitrary direction and the chemical reaction. The governing equations are solved numerically by using alternate direct implicit (ADI) method together with the successive over relaxation (SOR) technique. The flow pattern with the effect of governing parameters, namely the buoyancy ratio W, diffusocapillary ratio w, and the Hartmann number Ha, is investigated. It is revealed from the numerical simulations that the average Nusselt number decreases; whereas the average Sherwood number increases as the orientation of magnetic field is shifted from horizontal to vertical. Moreover, the effect of buoyancy due to species concentration on the flow is stronger than the one due to thermal buoyancy. The increase in diffusocapillary parameter, w causes the average Nusselt number to decrease, and average Sherwood number to increase.
Saleem, M, Hossain, MA, Saha, SC & Gu, YT 2014, 'Heat Transfer Analysis of Viscous Incompressible Fluid by Combined Natural Convection and Radiation in an Open Cavity', Mathematical Problems in Engineering, vol. 2014, pp. 1-14.
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The effect of radiation on natural convection of Newtonian fluid contained in an open cavity is investigated in this study. The governing partial differential equations are solved numerically using the Alternate Direct Implicit method together with the Successive Overrelaxation method. The study is focused on studying the flow pattern and the convective and radiative heat transfer rates are studied for different values of radiation parameters, namely, the optical thickness of the fluid, scattering albedo, and the Planck number. It was found that, in the optically thin limit, an increase in the optical thickness of the fluid raises the temperature and radiation heat transfer of the fluid. However, a further increase in the optical thickness decreases the radiative heat transfer rate due to increase in the energy level of the fluid, which ultimately reduces the total heat transfer rate within the fluid.
SATO, H, MANABE, K-I, ITO, K, WEI, D & JIANG, Z 2014, 'Development of Servo-Type Micro-Hydromechanical Deep-Drawing Apparatus and Micro Deep-Drawing Experiments of Circular Cups', Journal of the Japan Society for Technology of Plasticity, vol. 55, no. 636, pp. 44-49.
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A micro-hydromechanical deep-drawing (MHDD) apparatus for manufacturing a micro-complex-shape components and increasing of drawn cup accuracy has been developed in this study. This apparatus with a simple forming process mechanism can achieve high dimensional accuracy using servo press mechanics with a double-action type, one-stroke forming process without transferring and positioning, force control, and fine flow rate control of the pressure medium. It is confirmed that the MHDD apparatus developed can prevent wrinkling by applying an appropriate constant gap and stably generate the counterpressure. Micro-drawn cups of 0.8mm diameter are successfully fabricated. Also, the effects of counterpressure on drawability and dimensional accuracy at the bottom of the cup are investigated for phosphor bronze, stainless-steel, and pure titanium foils with a thickness of 50µm. The appropriate counterpressure applied in MHDD results in wrinkling constraint and a reduction in frictional drawing force. Consequently, it is concluded that the forming limit and dimensional accuracy can be improved by MHDD.
Sato, H, Manabe, K-I, Kondo, D, Wei, D & Jiang, Z 2014, 'Formability of Micro Sheet Hydroforming of Ultra-fine Grained Stainless Steel', Procedia Engineering, vol. 81, pp. 1463-1468.
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The formability of ultra-fine grained stainless steel is investigated in micro hydromechanical deep drawing. The materials used are ultra-fine grained stainless steel and SUS304-H with thickness of 20 and 50 μm. The micro cups are successfully fabricated for the ultra-fine grained stainless steel but it cannot be fabricated for SUS304-H with thickness of 20 μm. The fracture type of ultra-fine grained stainless steel foil is the shortage of tensile strength at plain strain state and does not change with a decrease of the thickness. In contrast, the fracture type of SUS304-H foil changes to the bending deformation with decreasing the thickness due to its low ductility. The ultra-fine grained metal foil is required to obtain the high formability and fabricate the sharp micro cups.
Schallow, J, Erohin, O, Ernst, J, Roubanov, D, Deuse, J & Eigner, M 2014, 'Prospektive Ermittlung von Montagearbeitsinhalten', Zeitschrift für wirtschaftlichen Fabrikbetrieb, vol. 109, no. 11, pp. 843-847.
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Kurzfassung Das Ziel einer prospektiven Ermittlung und einheitlichen Abbildung von Montagearbeitsinhalten in der Digitalen Fabrik wird durch die Entwicklung einer modularen Gesamtsystematik unter durchgängigem Einsatz digitaler Werkzeuge in unterschiedlichen Phasen des Produktentstehungsprozesses realisiert. Die Gesamtsystematik wird hierbei nahtlos in bestehende Softwarelandschaften von der Produktentwicklung über die Prozessplanung bis hin zum Arbeits- und Zeitstudium integriert und stellt die Konsistenz der digitalen Abbildung von Montagearbeitsinhalten sicher.
Schallow, J, Ludevig, J, Schmidt, M, Deuse, J & Marczinski, G 2014, 'Future prospects for digital manufacturing Understanding, realization status and development potential of digital production planning', WT Werkstattstechnik, vol. 104, no. 3, pp. 139-145.
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Within an extensive survey carried out by the Institute of Production Systems (IPS) at TU Dortmund University and CIM Aachen GmbH, a precise evaluation of the realization status and expected trends in digital manufacturing has been won. Main potential for the future, identified by 83 experts from all branches, are transparent and standardized planning workflows, modular and open data standards and an improved utilization of existing digital information.
Sick, N, Blug, M & Leker, J 2014, 'The Influence of Raw Material Prices on the Development of Hydrogen Storage Materials: The Case of Metal Hydrides', Journal of the Knowledge Economy, vol. 5, no. 4, pp. 735-760.
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© Springer Science+Business Media New York 2012. Hydrogen holds a prominent role as renewable energy carrier of the future due to its high gravimetric energy density. However, the most urgent technological challenge—especially concerning mobile applications in fuel cell vehicles—is the development of appropriate hydrogen storage options. In this context, metal hydrides are promising candidates in terms of development potential and increasing storage density. Our research outlines the so-far neglected influence of raw material prices on the decision which metal hydride is to date the most capable option to pursue. Using scenario analysis, we picture the impact of possible price developments depending on diffusion speed of fuel cell technologies into the automotive market, further applications of the corresponding raw materials, and other external influence factors. The main practical implication of our approach consists in enhancing the understanding of constantly changing market conditions—in our case scarcity and prices of the needed raw materials—and their impact on technology assessment in an early stage of the innovation process. In a superior context, our results in terms of metal hydrides can be adapted to other technologies and thus contribute to design a general model illustrating the influence of raw material prices on the development of energy technologies.
Siddiqa, S, Hossain, MA & Saha, SC 2014, 'The effect of thermal radiation on the natural convection boundary layer flow over a wavy horizontal surface', International Journal of Thermal Sciences, vol. 84, pp. 143-150.
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Sojoudi, A, Mazloomi, A, Saha, SC & Gu, YT 2014, 'Similarity Solutions for Flow and Heat Transfer of Non-Newtonian Fluid over a Stretching Surface', Journal of Applied Mathematics, vol. 2014, pp. 1-8.
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Similarity solutions are carried out for flow of power law non-Newtonian fluid film on unsteady stretching surface subjected to constant heat flux. Free convection heat transfer induces thermal boundary layer within a semi-infinite layer of Boussinesq fluid. The nonlinear coupled partial differential equations (PDE) governing the flow and the boundary conditions are converted to a system of ordinary differential equations (ODE) using two-parameter groups. This technique reduces the number of independent variables by two, and finally the obtained ordinary differential equations are solved numerically for the temperature and velocity using the shooting method. The thermal and velocity boundary layers are studied by the means of Prandtl number and non-Newtonian power index plotted in curves.
Sojoudi, A, Saha, SC, Khezerloo, M & Gu, YT 2014, 'Unsteady Natural Convection Within a Porous Enclosure of Sinusoidal Corrugated Side Walls', Transport in Porous Media, vol. 104, no. 3, pp. 537-552.
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Steffen, M & Deuse, J 2014, '5 Thesen zur organisationalen Kompetenz für Produktionssystemverbesserungen', Zeitschrift für wirtschaftlichen Fabrikbetrieb, vol. 109, no. 10, pp. 708-712.
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Kurzfassung Ziel des Beitrags ist die Diskussion empirischer Forschungsergebnisse in Bezug auf verschiedene Elemente organisationaler Kompetenz für Produktionssystemverbesserungen sowie die Ableitung von Handlungsempfehlungen. Grundlage bilden Projektergebnisse über Herausforderungen und Folgen neuer Produktionssysteme. Durch Analyse von über 30 Interviews wurden verschiedene Thesen herausgearbeitet. Ein Auszug von 5 Thesen über Kompetenzanforderungen, -entwicklung und -verankerung wird im Beitrag vorgestellt.
STEIN, NV & SICK, N 2014, 'TECHNOLOGICAL DISTANCE IN ACADEMIC COLLABORATIONS: EVIDENCE FROM BATTERY RESEARCH', International Journal of Innovation Management, vol. 18, no. 06, pp. 1440011-1440011.
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Technological distance is one important factor within research projects to enhance or prevent successful knowledge transfer for innovation. To get a better understanding of bridging mechanisms of diverging technological distances, we compare publication-based and individually perceived technological distances of collaboration partners in a multi-disciplinary battery research project. Differences hint at already bridged or non-bridged technological distances. Further information, given during expert interviews, present reasons for different knowledge transfer and recombination mechanisms in different dyadic collaborations. We generally find evidence that technological distance can be bridged by reducing geographical or social distances. When research activities are really complementary and collaboration partners have a common (technical) language, there is less need of decreasing other distances. Integrating research along the traditional battery value chain needs more social or geographical proximity to decrease and not just bridge technological distance at least in a practical way.
Sun, Y, Zhao, L, Huang, S, Yan, L & Dissanayake, G 2014, 'L-2-SIFT: SIFT feature extraction and matching for large images in large-scale aerial photogrammetry', ISPRS JOURNAL OF PHOTOGRAMMETRY AND REMOTE SENSING, vol. 91, pp. 1-16.
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The primary contribution of this paper is an efficient feature extraction and matching implementation for large images in large-scale aerial photogrammetry experiments. First, a Block-SIFT method is designed to overcome the memory limitation of SIFT for extracting and matching features from large photogrammetric images. For each pair of images, the original large image is split into blocks and the possible corresponding blocks in the other image are determined by pre-estimating the relative transformation between the two images. Because of the reduced memory requirement, features can be extracted and matched from the original images without down-sampling. Next, a red-black tree data structure is applied to create a feature relationship to reduce the search complexity when matching tie points. Meanwhile, tree key exchange and segment matching methods are proposed to match the tie points along-track and across-track. Finally, to evaluate the accuracy of the features extracted and matched from the proposed L2-SIFT algorithm, a bundle adjustment with parallax angle feature parametrization (ParallaxBA1The ParallaxBA source code is available open-source at OpenSLAM http://openslam.org/ParallaxBA.html. The features of the test datasets in this paper as the input to ParallaxBA are also available at OpenSLAM.1) is applied to obtain the Mean Square Error (MSE) of the feature reprojections, where the feature extraction and matching result is the only information used in the nonlinear optimisation system. Seven different experimental aerial photogrammetric datasets are used to demonstrate the efficiency and validity of the proposed algorithm. It is demonstrated that more than 33 million features can be extracted and matched from the Taian dataset with 737 images within 21h using the L2-SIFT algorithm. In addition, the ParallaxBA involving more than 2.7 million features and 6 million image points can easily converge to an MSE of 0.03874. The C/C++ source code for th...
To, AW-K, Paul, G & Liu, D 2014, 'Surface-Type Classification Using RGB-D.', IEEE Trans Autom. Sci. Eng., vol. 11, no. 2, pp. 359-366.
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This paper proposes an approach to improve surface-type classification of images containing inconsistently illuminated surfaces. When a mobile inspection robot is visually inspecting surface-types in a dark environment and a directional light source is used to illuminate the surfaces, the images captured may exhibit illumination variance that can be caused by the orientation and distance of the light source relative to the surfaces. In order to accurately classify the surface-types in these images, either the training image dataset needs to completely incorporate the illumination variance or a way to extract color features that can provide high classification accuracy needs to be identified. In this paper diffused reflectance values are extracted as new color features to classifying surface-types. In this approach, Red, Green, Blue-Depth (RGB-D) data is collected from the environment, and a reflectance model is used to calculate a diffused reflectance value for a pixel in each Red, Green, Blue (RGB) color channel. The diffused reflectance values can be used to train a multiclass support vector machine classifier to classify surface-types. Experiments are conducted in a mock bridge maintenance environment using a portable RGB-Depth sensor package with an attached light source to collect surface-type data. The performance of a classifier trained with diffused reflectance values is compared against classifiers trained with other color features including RGB and Lcolor spaces. Results show that the classifier trained with the diffused reflectance values can achieve consistently higher classification accuracy than the classifiers trained with RGB and Lab features. For test images containing a single surface plane, diffused reflectance values consistently provide greater than 90% classification accuracy; and for test images containing a complex scene with multiple surface-types and surface planes, diffused reflectance values are shown to provide an increase i...
Trianni, A, Cagno, E & De Donatis, A 2014, 'A framework to characterize energy efficiency measures', Applied Energy, vol. 118, pp. 207-220.
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Wang, C, Peng, Q, Wu, J, He, X, Tong, L, Luo, Q, Li, J, Moody, S, Liu, H, Wang, R, Du, S & Li, Y 2014, 'Mechanical characteristics of individual multi-layer graphene-oxide sheets under direct tensile loading', Carbon, vol. 80, pp. 279-289.
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Wei, D, Lu, H, Jiang, Z & Manabe, K-I 2014, 'Surface Morphology of Micro Stepped Components in Micro Cross Wedge Rolling', Procedia Engineering, vol. 81, pp. 1902-1908.
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A novel microforming process - Micro Cross Wedge Rolling has been proposed, which is very promising in producing micro stepped components. It is inevitable to confront with huge challenges in the development of micro cross wedge rolling technology. The influences of miniaturization, especially size effect, on process, accuracy control and product quality have to be studied. A micro cross wedge rolling testing rig has been designed and manufactured. Micro stepped components have been fabricated successfully by adopting flat wedge tools on this rig. The effects of surface roughness of tool, grain size in workpiece and cross sectional area reduction on surface morphology of rolled workpiece have been investigated.
Wei, DB, Lu, HN, Jiang, ZY & Manabe, K 2014, 'Optimization of Micro Cross Wedge Rolling and Surface Morphology of Micro Stepped Components', Key Engineering Materials, vol. 622-623, pp. 964-969.
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A novel microforming process - Micro Cross Wedge Rolling (MCWR) has been developed, which is promising for fabricating micro stepped components used in micro electro-mechanical systems. Numerical simulations have been established and the effect of geometrical and process parameters such as forming angle α, stretching angle β and reduction ΔA have been studied. Micro stepped components have been fabricated successfully on a MCWR testing rig by adopting flat wedge tools. The effects of initial surface roughness of tool, grain size and cross section area reduction on surface morphology have been assessed quantitatively.
Wiegand, M, Konrad, B, Sousanabady, RJ, Willats, P & Deuse, J 2014, 'Quantification of variability by use of big data technology', Productivity Management, vol. 19, no. 5, pp. 35-38.
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Low variability is a major prerequisite in order to successfully implement methods of lean production. Yet, in practice minimizing and controlling variability cannot be achieved to a sufficient level. Therefore, this paper presents a new approach for a production management scheme of highly variable production systems, which is based on technologies and methods of Big Data Analysis.
Williams, PT, Kirby, R, Malecki, C & Hill, J 2014, 'Measurement of the bulk acoustic properties of fibrous materials at high temperatures', Applied Acoustics, vol. 77, pp. 29-36.
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It is common for fibrous porous materials to be used in high temperature applications such as automotive and gas turbine exhaust silencers. Understanding the effect of temperature on the acoustic properties of these materials is crucial when attempting to predict silencer performance. This requires knowledge of the bulk acoustic properties of the porous materials and so this article aims to quantify the effect of temperature on the bulk acoustic properties of three fibrous materials: rock wool, basalt wool and an E-glass fibre. Measurements are undertaken here using a standard impedance tube that has been modified to accommodate temperatures of up to 500 C. It is shown that measured data for the bulk acoustic properties may be collapsed using a standard Delany and Bazley curve fitting methodology provided one modifies the properties of the material flow resistivity and air to account for a change in temperature. Moreover, by using a previously proposed power law describing the dependence of the flow resistivity with temperature, one may successfully collapse data measured at every temperature and obtain the Delany and Bazley coefficients in the usual way. Accordingly, to predict the bulk acoustic properties of a fibrous material at elevated temperatures it is necessary only to measure these properties at room temperature, and then to apply the appropriate temperature corrections to the properties of the material flow resistivity and air when using the Delany and Bazley formulae. © 2013 Elsevier Ltd. All rights reserved.
Wu, J, Luo, Z, Zhang, Y & Zhang, N 2014, 'An interval uncertain optimization method for vehicle suspensions using Chebyshev metamodels', Applied Mathematical Modelling, vol. 38, no. 15-16, pp. 3706-3723.
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Xu, F & Saha, SC 2014, 'Transition to an unsteady flow induced by a fin on the sidewall of a differentially heated air-filled square cavity and heat transfer', International Journal of Heat and Mass Transfer, vol. 71, pp. 236-244.
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Yu, X, Jiang, Z, Zhao, J, Wei, D, Zhou, C & Huang, Q 2014, 'Effect of a grain-refined microalloyed steel substrate on the formation mechanism of a tight oxide scale', Corrosion Science, vol. 85, pp. 115-125.
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Zhang, A-W, Jiang, Z-Y, Wei, D-B, Jiao, S-H & Xu, C 2014, 'Analysis of Fishscaling Resistance of Low Carbon Heavy Plate Steels', Journal of Iron and Steel Research International, vol. 21, no. 4, pp. 469-475.
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The precipitates and hydrogen permeation behavior in three kinds of hot rolled low carbon heavy plate steels for enameling were analyzed; then, both sides of the steels were enameled. The experimental results show that a large amount of coarse Ti 4 C 2 S 2 and fine Ti(C, N) particles exist in the optimized Ti-bearing steel, quite a lot of fine Ti(C, N) particles exist in the optimized carbon steel, but only a little bit fine Ti(C, N) particles exist in the carbon steel. The fishscaling resistance of the steels can be correlated to the effective hydrogen diffusion coefficient, and a model of correlation between the effective hydrogen diffusion coefficient and the volume fraction of the precipitates was established and verified. The effective hydrogen diffusion coefficient should be lower than 3. 96 × 10 6 cm 2 /s to avoid fishscaling in heavy plate steels. © 2014 Central Iron and Steel Research Institute.
Zhao, J, Ding, H, Jiang, Z, Wei, D & Linghu, K 2014, 'Effects of Hydrogen on the Critical Conditions for Dynamic Recrystallization of Titanium Alloy During Hot Deformation', Metallurgical and Materials Transactions A, vol. 45, no. 11, pp. 4932-4945.
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Zhao, J, Ding, H, Zhao, W, Huang, M, Wei, D & Jiang, Z 2014, 'Modelling of the hot deformation behaviour of a titanium alloy using constitutive equations and artificial neural network', Computational Materials Science, vol. 92, pp. 47-56.
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Zhao, S, Hu, Y, Lu, J, Qiu, X, Cheng, J & Burnett, I 2014, 'Delivering Sound Energy along an Arbitrary Convex Trajectory', SCIENTIFIC REPORTS, vol. 4.
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Accelerating beams have attracted considerable research interest due to their peculiar properties and various applications. Although there have been numerous research on the generation and application of accelerating light beams, few results have been published on the generation of accelerating acoustic beams. Here we report on the experimental observation of accelerating acoustic beams along arbitrary convex trajectories. The desired trajectory is projected to the spatial phase profile on the boundary which is discretized and sampled spatially. The sound field distribution is formulated with the Green function and the integral equation method. Both the paraxial and the non-paraxial regimes are examined and observed in the experiments. The effect of obstacle scattering in the sound field is also investigated and the results demonstrate that the approach is robust against obstacle scattering. The realization of accelerating acoustic beams will have an impact on various applications where acoustic information and energy are required to be delivered along an arbitrary convex trajectory.
Abeywardena, D, Wang, Z, Dissanayake, G, Waslander, SL, Kodagoda, S & IEEE 1970, 'Model-aided State Estimation for Quadrotor Micro Air Vehicles amidst Wind Disturbances', 2014 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS 2014), IEEE/RSJ International Conference on Intelligent Robots and Systems, IEEE, Chicago, Illinois, pp. 4813-4818.
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© 2014 IEEE. This paper extends the recently developed Model-Aided Visual-Inertial Fusion (MA-VIF) technique for quadrotor Micro Air Vehicles (MAV) to deal with wind disturbances. The wind effects are explicitly modelled in the quadrotor dynamic equations excluding the unobservable wind velocity component. This is achieved by a nonlinear observability of the dynamic system with wind effects. We show that using the developed model, the vehicle pose and two components of the wind velocity vector can be simultaneously estimated with a monocular camera and an inertial measurement unit. We also show that the MA-VIF is reasonably tolerant to wind disturbances, even without explicit modelling of wind effects and explain the reasons for this behaviour. Experimental results using a Vicon motion capture system are presented to demonstrate the effectiveness of the proposed method and validate our claims.
Ang, KCS 1970, 'The accidental collaborator: participatory action research as an emergent framework for sustainable multi-stakeholder engagement', Australasian Association of Engineering Education (AAEE) Conference 2014, Australasian Association of Engineering Education (AAEE) Conference 2014, AAEE 2014, Wellington.
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BACKGROUNDAs part of a three-year review cycle, a series of post-graduate program review initiatives were conducted in 2013 by the Faculty of Engineering and Information Technology (FEIT) at the University of Technology, Sydney (UTS), Australia. This was conducted through an Industry Engagement Project utilising multiple research methods to gather information from various stakeholders.PURPOSEThis paper aims to present two levels of project reflections based on the postgraduate review initiatives conducted. Firstly, it reflects on the mechanisms that lead to the emergence of a multi-stakeholder action-research framework that is practitioner-orientated, reflective and collaborative. Secondly, it reflects on the attributes and skills necessary to inform such a framework.DESIGN/METHODThis paper draws from academic literature about emergent research processes and action-research mechanisms to support the reflections made. This paper reflects on the collaborative stakeholder engagement process that commenced in 2013 as a participatory action research process. The research process involved a series of research initiatives as consultation and collaborative mechanisms to investigate and review the current postgraduate courses on offer.RESULTSInformation elucidation through traditional research approaches (surveys, interviews) is perceived as insufficient for project robustness, sustainable engagement and knowledge validation. Through various research strategies, a pragmatic stakeholder engagement framework applicable to education and industry collaborative processes emerged. The collaborative action-research initiatives provided added momentum for a series of incremental changes in different Engineering and Information Technology (EIT) courses. Another key outcome is the inception of discipline-specific Professional Advisory boards (PAb) in 2014. These are networks of academics, students, graduates and industry members that undertake to advice and review ...
Ang, KCS & Aubrey, T 1970, 'Transforming multiple stakeholder insights into education action: developing a pragmatic EIT professional advisory framework', Proceedings of the Australasian Association of Engineering Education (AAEE) Conference 2014, AAEE - Annual Conference of Australasian Association for Engineering Education, AAEE 2014, Wellington.
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BACKGROUNDThis paper discusses the formation of a stakeholder engagement framework for a Professional Advisory board (PAb). These collaborative undertakings were initially conducted to review post-graduate programs in the Faculty of Engineering and Information Technology (FEIT) at the University of Technology Sydney (UTS). This led to the realisation of a pragmatic and collaborative engagement process that benefits industry and the education sector whilst developing students that are able to deal with current and emergent challenges.PURPOSE OR GOALThe PAb is a network of academics, students, alumni and industry members that undertakes to engage, advice and review discipline-specific faculty programs from multiple perspectives to ensure that programs remain relevant and valuable to industry. As the faculty moves towards reengineering their approach to teaching and learning as part of a university-wide initiative known as ‘Learning 2014’ (L2014), this provides the opportunity to shape a more engaged and collaborative teaching and learning culture within its programs.DESIGN/METHODSThe collaborative stakeholder process was built upon an intensive series of mixed methods and action research initiatives as engagement mechanisms. These pragmatic and emergent mechanisms involved quantitative surveys, focus groups, in-depth interviews, industry workshops and multiple rounds of academic consultations.RESULTSThe PAb framework was piloted in June 2014. Initial results from a feedback survey are also reported. The collaborative framework, whilst promising, engaging and conceptually robust, has not yet reached a stable state. The framework will be extended to other EIT disciplines in order to evaluate its outcomes across various disciplinary contexts and to optimise the framework’s efficacy for future iterations. This paper suggests a pragmatic and robust framework to integrate industry and stakeholder expectations with faculty program deliverables in a way th...
Aoun, C, Ang, K & Vatanasakdakul, S 1970, 'Where is the feedback! a decomposition of feedback mechanisms in an introductory information systems course', 20th Americas Conference on Information Systems, AMCIS 2014, Americas Conference on Information Systems, AMCIS, Savannah, Georgia, USA.
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While the importance of feedback to learning is well acknowledged in the pedagogical literature, the perceptions of multiple forms of feedback among learners is yet to attract significant attention, particularly in the IS context. Consequently, this research investigates the antecedent constituents of feedback and how they contribute to an overall perception of feedback in an introductory IS course. Building upon such investigation, the study explores how such an overall perception of feedback contributes to a favourable experience in a course. To such end, a research model grounded in the pedagogical literature was operationalised and quantitative empirical data collected and analysed using PLS. The results indicate that summative and generic assessment feedback were found to be significant towards formulating an overall perception of feedback, and that such perception is significant in influencing a learner's experience in a course. The findings hold important implications to theory and practice, particularly for IS education.
Barnes, B, Abeywardena, D, Kodagoda, S & Dissanayake, G 1970, 'Evaluation of feature detectors for KLT based feature tracking using the odroid U3', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, ARAA, Melbourne.
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Feature tracking is an integral part of most vision-based state estimation frameworks. However, tracking features at a sufficient frame rate is a challenging task for mobile robots such as Micro Aerial Vehicles (MAVs) due to their fast dynamics and limited on-board computing resources. Recent developments in smartphone processors have led to embedded computing platforms that are ideal on-board computers for MAV state estimation. This paper analyses the performance of a Kanade-Lucas-Thomasi (KLT) based feature tracker on a state-of-theart embedded computing platform suitable for on-board MAV state estimation. It compares the performance of different implementations of the feature tracker using four different lowcomplexity feature detectors. The experimental results presented herein may serve as guidelines for the selection of a feature detector, image resolution, framerate and feature quantity when developing on-board feature tracking systems based on ARM Cortex-A9 embedded computers.
Barthelmey, A, Störkle, D, Kuhlenkötter, B & Deuse, J 1970, 'Cyber Physical Systems for Life Cycle Continuous Technical Documentation of Manufacturing Facilities', Procedia CIRP, Elsevier BV, pp. 207-211.
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Continuous rising of requirements to create technical documentation results in high effort in terms of time and costs to create a complete and up to date documentation for manufacturers. In case of any technical modifications of machines the technical documentation also has to be updated. In fact these updates are lacking in most cases. In this paper, the authors propose a methodology for a self-organized creation of technical documentation to enable an up to date state throughout the Product Life Cycle. A complete and up to date technical documentation provides benefits to customers as well as suppliers of manufacturing facilities. The new approach is based on integration and communication of all components and modules such as machine tool, transportation and handling technology etc. via "Cyber Physical Systems". © 2014 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.
Best, G & Anstee, S 1970, 'Motion planning for autonomous underwater vehicle supervision', Australasian Conference on Robotics and Automation, ACRA.
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Autonomous Underwater Vehicles (AUV) play an important role in surveying undersea environments. It is often essential for AUV operators to be able to supervise the progress of their vehicles during missions, to enable informed decisions in real-time. In this paper we consider supervision of an AUV executing a preplanned mission from a mobile surface vessel equipped with an acoustic communications system. We consider the surface vessel to be supervising effectively if it is stationary and located within a fixed maximum range from the AUV. When the supervising vessel is not stationary, we assume it is transiting to the next supervision point. We seek trajectory plans that maximise the proportion of time the supervising vessel is able to supervise the AUV effectively. In this paper we propose two solutions to this trajectory planning problem; a greedy planner, which instructs the supervising vessel to move when the AUV moves beyond its effective range but restricts the vessel to points along the path of the AUV; and a global optimiser based on a genetic algorithm that relaxes this limitation. Sea-trial and simulation results demonstrate the effectiveness of our proposed solutions.
Best, G & Moghadam, P 1970, 'An evaluation of multi-modal user interface elements for tablet-based robot teleoperation', Australasian Conference on Robotics and Automation, ACRA.
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For robot teleoperation systems, tablet and smart phone user interfaces provide portability and accessibility to allow anyone anywhere to connect to the system quickly and easily. This can be highly advantageous for disaster-relief robot systems where timing is critical. However, the small screen size and unconventional input methods mean that traditional teleoperation user interface elements, such as multiple visual windows, keyboards and mice, are no longer effective. In this paper we propose and investigate multi-modal user interface design principles as a solution for effective tablet-based teleoperation. We present our tablet user interface that features multiple complementary modalities of control and feedback mechanisms. It allows the operator to perceive the robot's environment and state by exciting their senses of vision, hearing and touch with overlaying visual displays, virtual 3-D audio and vibration feedback. The operator commands actions to the robot through the use of intuitive input methods utilising the touch screen and accelerometer. We analyse these design principles by performing a user study that focuses on finding what aspects of the multi-modal user interface affect the system performance during a navigation task. The study highlights advantages of multimodal user interfaces for robot teleoperation and makes several findings to be considered when developing similar systems.
Cagno, E, Trianni, A, Worrell, E & Miggiano, F 1970, 'Barriers and Drivers for Energy Efficiency: Different Perspectives from an Exploratory Study in the Netherlands', Energy Procedia, 6th International Conference on Applied Energy (ICAE), Elsevier BV, Taipei, TAIWAN, pp. 1256-1260.
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Carmichael, MG, Moutrie, B & Liu, D 1970, 'A framework for task-based evaluation of robotic coworkers', 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), IEEE, Singapore, pp. 1362-1367.
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© 2014 IEEE. Compared to a robotic system that performs a task alone, a robot coworker performing tasks in collaboration with a human operator is subject to additional constraints which can limit the ability of the system to perform the task as required. This work presents a framework for analyzing the ability of a robotic coworker to perform specific tasks in collaboration with a human. The framework allows systematic evaluation of robotic systems based on traditional robot performance measures such as reachable workspace and payload capacity, as well as considering additional factors which arise due to the task being performed collaboratively with a human; such as the reach and strength of the human, human-robot collision, and satisfying desired assistance paradigms. Application of the framework is demonstrated in a case study analyzing a robot designed to assist a human during a materials handling task.
Chan, ENK, Huynh, P & Nguyen, TT 1970, 'An investigation on the effects of chamber wall's elasticity on blood flow in a LVAD pump', Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014, Australasian Fluid Mechanics Conference, RMIT University, Melbourne, Australia.
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Left Ventricular Assist Device (LVAD) is a pump that is designed to provide life support to patients with end stage heart failure. In an effort to ensure the safety of LVAD, the pumping mechanics must not exert excessive stress on the blood or hemolysis would occur. This study investigates the effects of chamber wall's elasticity (isotropic) from common materials on blood flow in a LVAD, especially the shear stress resulted therein. The materials considered are titanium, diamond-like carbon (DLC), 2-methacryloyloxy ethyl phosphorylcholine (MPC) polymer, segmented polyurethane (SPU), polyurethane (PEU), and a material with properties corresponding to blood vessels, which is used as the reference. The study employs a Fluid Structure Interaction (FSI) simulation software suite to couple Computational Fluid Dynamics (CFD) with mechanical simulation (ANSYS). The test system is a centrifugal pump based on a 2012-Jarvik Patent. The flow through the pump is driven by an impeller rotating at set speed to achieve a pre-set blood flowrate. The results show that there is no significant difference in turbulent dissipation rate among the different chamber-wall materials, with PEU giving closest figure to the blood vessels'. On the other hand, regarding wall shear stress which is an important factor in hemolysis, titanium, DLC and SPU result in similar maximum values, whereas MPC, PEU and blood vessel material give noticeably lower ones.
Dantanarayana, L, Ranasinghe, R, Tran, A, Liu, D & Dissanayake, G 1970, 'A Novel Collaboratively Designed Robot to Assist Carers', SOCIAL ROBOTICS, International Conference on Social Robotics (ICSR), SPRINGER-VERLAG BERLIN, Sydney, Australia, pp. 105-114.
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© Springer International Publishing Switzerland 2014. This paper presents a co-design process and an assisted navigation strategy that enables a novel assistive robot, Smart Hoist, to aid carers transferring non-ambulatory residents. Smart Hoist was codesigned with residents and carers at IRT Woonona residential care facility to ensure that the device can coexist in the facility, while providing assistance to carers with the primary aim of reducing lower back injuries, and improving the safety of carers and patients during transfers.The Smart Hoist is equipped with simple interfaces to capture user intention in order to provide assisted manoeuvring. Using the RGB-D sensor attached to the device, we propose a method of generating a repulsive force that can be combined with the motion controller’s output to allow for intuitive manoeuvring of the Smart Hoist, while negotiating with the environment.Extensive user trials were conducted on the premises of IRTWoonona residential care facility and feedback from end users confirm its intended purpose of intuitive behaviour, improved performance and ease of use.
Deuse, J, Roßmann, J, Kuhlenkötter, B, Hengstebeck, A, Stern, O & Klöckner, M 1970, 'A Methodology for the Planning and Implementation of Service Robotics in Industrial Work Processes', Procedia CIRP, Elsevier BV, pp. 41-46.
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© 2014 Published by Elsevier B.V. The gap between capability and practical application of service robotics increases constantly, especially regarding to SMEs. In order to overcome the affiliated obstacles, easily applicable methods supporting users in the planning and implementation of robot solutions need to be developed. Therefore, the proposed methodology determines a useful degree of automation for manual work processes by the help of four main components. A potential customer will be able to join an internet portal. Via this portal, the customer may add data on specific manual work processes, adjacent influencing parameters and additional framework conditions. This data is then forwarded to an associated planning kernel which derives information on different service robot components from a data base. By comparing the requirements regarding the specific manual work process with the different robot characteristics, the planning kernel produces results in two categories. First, the system recommends robot components that can be applied for the specific work process and second, motion plans for the selected service robot system. In order to enhance practical usability and transparency for the customer, the planning kernel is connected to a simulation. Regarding this simulation, the robot components and motions will be automatically visualized to the customer. Consequently, the customer will be able to easily decide on a potential robot implementation in order to support employees and improve the work processes. In practical application, this solution can especially improve the competitiveness of SMEs.
Falque, R, Vidal-Calleja, T, Miro, JV, Lingnau, DC & Russell, DE 1970, 'Background segmentation to enhance remote field eddy current signals', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, ARAA, Melbourne University.
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Pipe condition assessment is critical to avoid breakages. Remote Field Eddy Current (RFEC) is a commonly used technology to assess the condition of pipes. The nature of this technology induces some particular noise into its measurements. In this paper, we develop a 3D simulation based on the Finite Element Analysis to study the properties of this noise. Moreover, we propose a filtering process based on a modified version of graph-cuts segmentation method to remove the influence of this noise. Simulated data together with an experimental data-set obtained from a real RFEC inspection show the validity of the proposed approach.
Gallage, HNP, Saha, SC & Gu, YT 1970, 'Deformation of a three-dimensional red blood cell in a stenosed micro-capillary', 8th Australasian Congress on Applied Mechanics, ACAM 2014, as Part of Engineers Australia Convention 2014, pp. 273-279.
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Red blood cells (RBCs) exhibit different types of motions and deformations when the blood flows through capillaries. Interestingly, due to the complex three-dimensional structure of the RBC membrane, RBCs show three-dimensional motions and deformations in the blood flow. These motions and deformations of the RBCs highly depend on the stiffness of the RBC membrane and on the geometrical parameters of the capillary through which blood flows. However, capillaries always do not have uniform cross sections and some capillaries have stenosed segments, where cross sectional area suddenly reduces. Further, some diseases can alter the stiffness of the RBC membrane drastically. In this study, the deformation behaviour of a single three-dimensional RBC is examined, when it moves through a stenosed capillary. A three-dimensional spring network is used to model the RBC membrane. The RBC's inside and outside fluids are discretized into a finite number of mass points and treated by smoothed particle hydrodynamics (SPH) method. The capillary is considered as a rigid tube with a stenosed section. The deformation index, mean velocity and total energy of the RBC are analysed when it flows through the stenosed capillary. Further, motion and deformation of the RBCs with different membrane stiffness (KB) are compared when they flow through the stenosed segment of the capillary. The simulation results demonstrate the RBCs are subjected to a larger deformation when they move through the stenosed part of the capillary and the RBCs with lower KB values easily pass through the stenosed segment of the capillary. Further, RBCs having higher KB values have a lower mean velocity and it leads to slow down the overall blood flow rate.
Guertler, MR, Elezi, F & Lindemann, U 1970, 'How to assess actors for an Open Innovation-project?', RISK AND CHANGE MANAGEMENT IN COMPLEX SYSTEMS, 16th International Dependency and Structure Modelling Conference (DSM), Carl Hanser Verlag GmbH & Co. KG, Paris, FRANCE, pp. 359-368.
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Guertler, MR, Holle, M & Lindemann, U 1970, 'Open Innovation: Industrial Application and Demands – a Qualitative Study', The R&D Management Conference 2014, Fraunhofer Verlag, Stuttgart, pp. 1024-1030.
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Open Innovation (OI) opens a company’s innovation process to its environment in order to enable a purposeful collaboration. Over the last 10 years OI has become an important part within the innovation management in industry and academia. Therefore, we conducted an explorative interview study in 2012 to analyse how and with which results and success OI is applied in industry. The goal was to evaluate benefits and risks mentioned in literature as well as to analyse the utilization of OI-methods, and to identify (so far) unconsidered challenges and potential solution strategies for barriers against OI. Based on this, industry demands in terms of research gaps were derived. Participants of the study in 2012 were 13 German large-scale enterprises (including one SME) from different branches, and with different product/services portfolios and types of customers. In addition to companies with OI experience, we also interviewed companies without OI experience to allow the identification of possible concerns against OI. Though the overall feedback was positive, also some critical feedback, challenges and needs regarding the application of OI were stated. The results of the study are consistent with previous studies but reveal additional challenges and demands which have not been in the focus so far. To evaluate the pre-published results of the study, we conducted a workshop with eight Bavarian medium-scale enterprises from different industries and with different types of products/services and types of customers. These companies had no or only small experience with OI. The goal of the workshop was to identify expectations towards OI as well as concerns against OI, in order to evaluate the results of the interview study. This paper presents the results of the study and the workshop, and derives research gaps and future demands.
Guertler, MR, Holle, M, Guber, D & Lindemann, U 1970, 'How to determine a company's open innovation situation?', Proceedings of International Design Conference, DESIGN, 13th International Design Conference, DESIGN SOC, Dubrovnik, COLOMBIA, pp. 1541-1550.
Guertler, MR, Lewandowski, P & Lindemann, U 1970, 'Stakeholder-Analysis featuring Open Innovation', XXV ISPIM Conference - Innovation for Sustainable Economy and Society, Dublin, pp. 1-19.
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By opening a company’s innovation process to its environment, Open Innovation (OI) allows advantages such as better market orientation, reduced development risks and the utilization of external expertise. However, so far, the selection of appropriate external and internal OI-project actors is still a challenge for companies; adequate methodological support is limited and existing OI-specific selection processes or processes from other fields bear several deficits. Therefore our goal is the development of an OI-specific integrated selection approach. Based on a systematic comparison of stakeholder- and Lead-User identification processes as well as OI-specific requirement analysis, this work presents a first integrated approach for identifying and selecting OI-actors by combining stakeholder and Lead-User identification. An initial evaluation of the approach in industrial application was successful. Observed benefits and existing points of improvement are discussed.
Halkon, B, Mitchell, S, Payne, T & Carbo, J 1970, 'Biomechanical Measurements of Human Impacts in Basketball', Procedia Engineering, 10th Conference of the International-Sports-Engineering-Association, Elsevier BV, Sheffield Hallam Univ, Sheffield, ENGLAND, pp. 214-219.
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Despite significant advances in materials and manufacturing techniques applied to sports protective equipment in recent years, sports injuries due to impact, contusions in particular, continue to occur. In this paper, a test methodology aimed at collecting data from laboratory-simulated human-on-human impacts in Basketball is presented. The study was executed in three stages with data being collected from: i) human on instrumented bag; ii) impactor on instrumented bag and iii) impactor on instrumented human impacts. In all cases, high-speed video and/or kinematic motion data capture systems were used to obtain parameters such as inbound/outbound velocities, contact durations while resistive ink technology pressure sensing films were used to estimate parameters such as pressure distributions, peak pressures, contact areas, impact forces. Elite-level athletes were used in all human trials to ensure that impact techniques and levels representative of the elite game were obtained and that tolerance to impacts was similarly representative. Two common strikes were simulated: knee on thigh and elbow on rib/torso. Five participants were used to collect the human-on-bag data while 12 participants were used to collect the impactor-on-human data. Between three and five impacts per scenario were performed to enable noise averaging and, importantly, likely injurycausing outlier capture. © 2014 Published by Elsevier Ltd.
Harfield, P, Halkon, B, Mitchell, S, Phillips, I & May, A 1970, 'A Novel, Real-time Biomechanical Feedback System for Use in Rowing', Procedia Engineering, 10th Conference of the International-Sports-Engineering-Association, Elsevier BV, Sheffield Hallam Univ, Sheffield, ENGLAND, pp. 126-131.
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Biomechanical feedback in water-based rowing is traditionally presented as paper reports or video overlaid with data once a session has been completed. Research into the provision of extrinsic feedback in sport suggests that real-time feedback can lead to skill acquisition and, when appropriately applied, lead to skill retention during competition and therefore a positive performance outcome. This paper presents a novel system architecture that delivers real-time feedback using commercially available off-the-shelf components. The development of a rowing specific system to test a range of feedback strategies is presented, including fading feedback, mixing feedback modalities and varying of the frequency and timing of feedback. MoSync, a cross-platform smartphone development language, was used to write the client application while the server was written as an embedded application in C and Lua that ran on top of the OpenWrt open-source router operating system. Data was transmitted wirelessly across a Wi-Fi network. A human-centred design process was led by a group of highperformance athletes and coaches and the system was shown to deliver data to up to 10 clients simultaneously. Future research will investigate the efficacy of a variety of different feedback strategies to rowers. © 2014 Published by Elsevier Ltd.
Hassan, M, Liu, D, Huang, S & Dissanayake, G 1970, 'Task oriented area partitioning and allocation for optimal operation of multiple industrial robots in unstructured environments', 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), IEEE, Marina Bay Sands, Singapore, pp. 1184-1189.
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© 2014 IEEE. When multiple industrial robots are deployed in field applications such as grit blasting and spray painting of steel bridges, the environments are unstructured for robot operation and the robot positions may not be arranged accurately. Coordination of these multiple robots to maximize productivity through area partitioning and allocation is crucial. This paper presents a novel approach to area partitioning and allocation by utilizing multiobjective optimization and voronoi partitioning. Multiobjective optimization is used to minimize: (1) completion time, (2) proximity of the allocated area to the robot, and (3) the torque experienced by each joint of the robot during task execution. Seed points of the voronoi graph for voronoi partitioning are designed to be the design variables of the multiobjective optimization algorithm. Results of three different simulation scenarios are presented to demonstrate the effectiveness of the proposed approach and the advantage of incorporating robots' torque capacity.
Khosoussi, K, Huang, S & Dissanayake, G 1970, 'Novel insights into the impact of graph structure on SLAM', 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2014), IEEE, Chicago, IL, pp. 2707-2714.
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© 2014 IEEE. SLAM can be viewed as an estimation problem over graphs. It is well known that the topology of each dataset affects the quality of the corresponding optimal estimate. In this paper we present a formal analysis of the impact of graph structure on the reliability of the maximum likelihood estimator. In particular, we show that the number of spanning trees in the graph is closely related to the D-optimality criterion in experimental design. We also reveal that in a special class of linear-Gaussian estimation problems over graphs, the algebraic connectivity is related to the E-optimality design criterion. Furthermore, we explain how the average node degree of the graph is related to the ratio between the minimum of negative log-likelihood achievable and its value at the ground truth. These novel insights give us a deeper understanding of the SLAM problem. Finally we discuss two important applications of our analysis in active measurement selection and graph pruning. The results obtained from simulations and experiments on real data confirm our theoretical findings.
Kirchner, N, Alempijevic, A, Virgona, A, Dai, X, Plöger, PG & Venkat, RK 1970, 'A robust people detection, tracking, and counting system', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, Australasian Robotics and Automation Association, Melbourne, Australia, pp. 1-8.
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The ability to track moving people is a key aspect of autonomous robot systems in real-world environments. Whilst for many tasks knowing the approximate positions of people may be sufficient, the ability to identify unique people is needed to accurately count people in the real world. To accomplish the people counting task, a robust system for people detection, tracking and identification is needed. This paper presents our approach for robust real world people detection, tracking and counting using a PrimeSense RGBD camera. Our past research, upon which we built, is highlighted and novel methods to solve the problems of sensor self-localisation, false negatives due to persons physically interacting with the environment, and track misassociation due to crowdedness are presented. An empirical evaluation of our approach in a major Sydney public train station (N=420) was conducted, and results demonstrating our methods in the complexities of this challenging environment are presented.
Kool, R & Trianni, A 1970, 'Introduction to panel 3 matching policies and drivers: Policies and directives to drive industrial efficiency', Eceee Industrial Summer Study Proceedings, pp. 259-260.
Lapko, Y, Trucco, P, Trianni, A & Nuur, C 1970, 'Implications for Collaborative Development of Reverse Distribution Network: A System Perspective', ADVANCES IN PRODUCTION MANAGEMENT SYSTEMS: INNOVATIVE AND KNOWLEDGE-BASED PRODUCTION MANAGEMENT IN A GLOBAL-LOCAL WORLD, APMS 2014, PT II, IFIP WG 5.7 International Conference on Advances in Production Management Systems (APSM), Springer International Publishing, Ajaccio, FRANCE, pp. 351-357.
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Lee, JJH, Frey, K, Fitch, R & Sukkarieh, S 1970, 'Fast path planning for precision weeding', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, ARAA, Melbourne, Australia.
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Agricultural robots have the potential to reduce herbicide use in agriculture and horticulture through autonomous precision weeding. One of the main challenges is how to efficiently plan paths for a robot arm such that many individual weeds can be processed quickly. This paper considers an abstract weeding task among obstacles and proposes an efficient online path planning algorithm for an industrial manipulator mounted to a mobile robot chassis. The algorithm is based on a multi-query approach, inspired by industrial bin-picking, where a database of high-quality paths is computed offline and paths are then selected and adapted online. We present a preliminary implementation using a 6-DOF arm and report results from simulation experiments designed to evaluate system performance with varying database and obstacle sizes. We also validate the approach using a Universal Robots UR5 manipulator and ROS interface.
Liu, DK, Dissanayake, G, Valls Miro, J & Waldron, KJ 1970, 'Infrastructure Robotics: Research Challenges and Opportunities', Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC), 31st International Symposium on Automation and Robotics in Construction, International Association for Automation and Robotics in Construction (IAARC), Sydney, Australia, pp. 43-49.
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Infrastructure robotics is about research on and development of methodologies that enable robotic systems to be used in civil infrastructure inspection, maintenance and rehabilitation. This paper briefly discusses the current research challenges and opportunities in infrastructure robotics, and presents a review of the research activities and projects in this field at the Centre for Autonomous Systems, University of Technology Sydney.
Lobocki, T & Brown, TA 1970, 'Root cause and fatigue analysis of traction winch failures', 8th Australasian Congress on Applied Mechanics, ACAM 2014, as Part of Engineers Australia Convention 2014, Australasian Congress on Applied Mechanics, Informit, Barton, ACT, pp. 540-548.
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This paper describes the investigation, analysis and proposed solutions to the problem of a regularly failing traction winch that resulted in significant and unacceptable downtime of crucial production machines. The winch's wire ropes fail on average about once a month. The reliability of the machine investigated is critical to the success of the business. A Root Cause Analysis (RCA) of the failing machine was conducted which identified the physical, human and latent root causes of the traction winch failures. The average number of cycles to failure for the wire ropes was only 1088 cycles (equating to approximately 24 days of service). Physical root causes were identified through theoretical fatigue analysis and visual inspection and scanning electron microscopy (SEM) to examine the fracture surface of the failed wire ropes. The analysis indicated that there were extensive bending fatigue cracks leading to total rope failure. It was concluded that the leading physical root cause of the premature failure of the traction winch was the bending fatigue failure in the wire rope caused by the specification of an undersized sheave and drum in the traction winch design.
Luo, L, Jiang, ZY, Wei, DB & He, XF 1970, 'Surface Modification of Titanium and its Alloys for Biomedical Application', Advanced Materials Research, International Conference on Advances in Manufacturing and Materials Engineering, Trans Tech Publications, Ltd., Kunming, PEOPLES R CHINA, pp. 1115-1120.
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Titanium and its alloys have excellent properties and are promising biomaterial in medical engineering field. A bioactive surface on a Ti substrate is a prerequisite for great performance and long service life of implants. Based on the mechanism for inducing cell/tissue responses, three kinds of methods, namely morphological, physicochemical and biochemical methods, are reviewed in this paper. Hybrid methods that integrate individual methods or have additional functions are also discussed.
Mondal, RN & Islam, MS 1970, 'Pressure-driven Flow Instability with Convective Heat Transfer Through a Curved Rectangular Duct of Small Aspect Ratio', Procedia Engineering, Elsevier BV, pp. 268-274.
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Nguyen, LV, Kodagoda, S, Ranasinghe, R & Dissanayake, G 1970, 'Mobile robotic wireless sensor networks for efficient spatial prediction', 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2014), IEEE, Chicago, IL, USA, pp. 1176-1181.
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This paper addresses the issue of monitoring physical spatial phenomena of interest utilizing the information collected by a network of mobile, wireless and noisy sensors that can take discrete measurements as they navigate through the environment. The spatial phenomenon is statistically modelled by a Gaussian Markov Random Field (GMRF) with hyperparameters that are learnt as the measurements accumulate over
time. In this context, the GMRF approximately represents the spatial field on an irregular lattice of triangulation by exploiting a stochastic partial differential equation (SPDE) approach, which benefits remarkably in computation due to the sparsity
of the precision matrix. A technique of the one-step-ahead forecast is employed to predict the future measurements that are required to find the optimal sampling locations. It is shown that optimizing the sampling path problem with the logarithm
of the determinant either of a covariance matrix using a GP model or of a precision matrix using a GMRF model for mobile robotic wireless sensor networks (MRWSNs) even by a greedy algorithm is impractical. This paper proposes an efficient novel
optimality criterion for the adaptive sampling strategy to find the most informative locations in taking future observations that minimize the uncertainty at unobserved locations. The computational complexity of our proposed method is linear, which makes the MRWSN scalable and practically feasible. The effectiveness of the proposed approach is compared and demonstrated using a pre-published data set with appealing results.
Niktash, A & Huynh, BP 1970, 'Numerical Simulation and Analysis of the Two-Sided Windcatcher Inlet\Outlet Effect on Ventilation Flow Through a Three Dimensional Room', Volume 2: Simple and Combined Cycles; Advanced Energy Systems and Renewables (Wind, Solar and Geothermal); Energy Water Nexus; Thermal Hydraulics and CFD; Nuclear Plant Design, Licensing and Construction; Performance Testing and Performance Test Codes; Student Paper Competition, ASME 2014 Power Conference, American Society of Mechanical Engineers, Baltimore, Maryland, USA, pp. 1-6.
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A windcatcher is a structure placed on the roof of a building for providing natural ventilation for interior space working by wind power. It draws out the inside stale air to the outside and supplies the outside fresh air for the building’s interior space. In this paper, the effect of different types of windcatcher’s inlet\outlet on the air flow, flow velocity and flowrate through a three-dimensional room fitted with a two-sided windcatcher is observed numerically, using a commercial computational fluid dynamics (CFD) software package. The standard RANS K-ε CFD method is used in the simulations. The flow pattern, flow velocity and flowrate of the inside ventilation flow is considered for the six different types of a two-sided windcatcher’s inlet\outlet. It is found that the shape of the inlet\outlet of windcatcher strongly affects flow pattern, flow velocity and flowrate and the performance of square windcatcher is higher than the circular one specially in ventilating the living area (lower part) of a room.
Norouzi, M, Miro, JV, Dissanayake, G & Vidal-Calleja, T 1970, 'Path planning with stability uncertainty for articulated mobile vehicles in challenging environments', 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2014), IEEE, Chicago, IL, pp. 1748-1753.
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© 2014 IEEE. This article proposes a probabilistic approach to account for robot stability uncertainty when planing motions over uneven terrains. A novel probabilistic stability criterion derived from the cumulative distribution of a tip-over metric is introduced that allows a safety constraint to be dynamically updated by available sensor data as it becomes available. The proposed safety constraint authorizes the planner to generates more conservative motion plans for areas with higher levels of uncertainty, while avoids unnecessary caution in well-known areas. The proposed systematic approach is particularly applicable to reconfigurable robots that can assume safer postures when required, although is equally valid for fixed-configuration platforms to choose safer paths to follow. The advantages of planning with the proposed probabilistic stability metric are demonstrated with data collected from an indoor rescue arena, as well as an outdoor rover testing facility.
Oberst, S, Nava-Baro, E, Lai, JCS & Evans, TA 1970, 'An innovative signal processing technique for the extraction of ants' walking signals', INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control, INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control.
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Eusocial insects such as bees, ants and termites communicate multi-modally using chemical, visual, tactile and vibrational cues. While much work has been done on chemical and visual communications, the tactile and vibrational communication channel is somewhat neglected. Recent research indicates that structural vibrations caused by ants can be used to identify their activity level. However, these structural vibrations are caused by the response of the substrate excited by ants walking. The objective of this study is to determine the footprint of ants walking by separating the response of the substrate from the walking signal. The vibration of the substrate (in this case, a wooden veneer) caused by ants walking is measured by a laser vibrometer in an experimental setup isolated from environmental vibrations. By filtering the recorded vibration signal using a technique based on the dynamics in phase space followed by deconvolution from the response of the veneer using TIKHONOV regularisation, the ant's walking signal is extracted and its nature determined.
Parnell, J & Wassermann, J 1970, 'Communicating the noise message', INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control.
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This paper revisits the key aspects of noise communication addressed by the authors in a previous paper and provides a summary of current practice and suggests strategies for improving the communication of information on noise so that it achieves the best outcomes. A discussion is presented on the limitations of noise assessments and public understanding as well as the consequences of good/bad noise communication. In addition, this paper also examines contemporary issues of changing expectations in communities and the dissemination of misinformation.
Patel, M, Miro, JV & Dissanayake, G 1970, 'A probabilistic approach to learn activities of daily living of a mobility aid device user', 2014 IEEE International Conference on Robotics and Automation (ICRA), 2014 IEEE International Conference on Robotics and Automation (ICRA), IEEE, Hong Kong, pp. 969-974.
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© 2014 IEEE. The problem of inferring human behaviour is naturally complex: people interact with the environment and each other in many different ways, and dealing with the often incomplete and uncertain sensed data by which the actions are perceived only compounds the difficulty of the problem. In this paper, we propose a framework whereby these elaborate behaviours can be naturally simplified by decomposing them into smaller activities, whose temporal dependencies can be more efficiently represented via probabilistic hierarchical learning models. In this regard, patterns of a number of activities typically carried out by users of an ambulatory aid device have been identified with the aid of a Hierarchical Hidden Markov Model (HHMM) framework. By decomposing the complex behaviours into multiple layers of abstraction the approach is shown capable of modelling and learning these tightly coupled human-machine interactions. The inference accuracy of the proposed model is proven to compare favourably against more traditional discriminative models, as well as other compatible generative strategies to provide a complete picture that highlights the benefits of the proposed approach, and opens the door to more intelligent assistance with a robotic mobility aid.
Piyathilaka, L & Kodagoda, S 1970, 'Active visual object search using affordance-map in real world: A human-centric approach.', ICARCV, International Conference on Control, Automation, Robotics and Vision, IEEE, Singapore, pp. 1427-1432.
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Human context is the most natural explanation why objects are placed and arranged in a particular order in an indoor environment. Usually, humans arrange objects in order to support their intended activities in a given environment. However, most of the common approaches for robotic object search involve modelling object-object relationships. In this paper, we hypothesize such relationships are centered around humans and bring human context to object search by modelling human-objects
relationships through affordance-map. It identifies locations in a 3D map which support a particular affordance using virtual human models. Therefore, our approach does not require to observe real humans in the scene. The affordance-map and object-human-robot relationship are then used to infer the object search
strategy. We tested our algorithm using a mobile robot that actively searched for the object “computer monitors” in an office environment with promising results
Piyathilaka, L & Kodagoda, S 1970, 'Affordance-map: A map for context-aware path planning', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, Australian Robotics and Automation Association Inc, Melbourne, pp. 1-8.
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'Context-awareness' could be one of the most desired fundamental abilities that a robot should have when sharing a workspace with humans co-workers. Arguably, a robot with appropriate context-awareness could lead to a better human robot interaction. In this paper, we address the problem of combining contextawareness with robotic path planning. Our approach is based on affordance-map, which involves mapping latent human actions in a given environment by looking at geometric features of the environment. This enables us to learn human context in an given environment without observing real human behaviours which themselves are a non-trivial task to detect. Once learned, affordance-map allows us to assign an affordance cost value for each grid location of the map. These cost maps are later used to develop a context-aware global path planning strategy by using the well known A∗ algorithm. The proposed method was tested in a real office environment and proved our algorithm is capable of moving a robot in a path that minimises the distractions to human co-workers.
Quin, P, Alempijevic, A, Paul, G & Liu, D 1970, 'Expanding wavefront frontier detection: An approach for efficiently detecting frontier cells', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, Australasian Robotics and Automation Association, Melbourne, pp. 1-10.
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Frontier detection is a key step in many robot exploration algorithms. The more quickly frontiers can be detected, the more efficiently and rapidly exploration can be completed. This paper proposes a new frontier detection algorithm called Expanding Wavefront Frontier Detection (EWFD), which uses the frontier cells from the previous timestep as a starting point for detecting the frontiers in the current timestep. As an alternative to simply comparing against the naive frontier detection approach of evaluating all cells in a map, a new benchmark algorithm for frontier detection is also presented, called Naive Active Area frontier detection, which operates in bounded constant time. EWFD and NaiveAA are evaluated in simulations and the results compared against existing state-of-the-art frontier detection algorithms, such as Wavefront Frontier Detection and Incremental-Wavefront Frontier Detection.
Ramirez-Portilla, A, Cagno, E & Trianni, A 1970, 'Is Innovation an Enabler of Energy Efficiency? An Exploratory Study of the Foundry Sector', Energy Procedia, 6th International Conference on Applied Energy (ICAE), Elsevier BV, Taipei, TAIWAN, pp. 1191-1195.
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Ranasinghe, R, Dantanarayana, L, Tran, A, Lie, S, Behrens, M & Liu, L 1970, 'Smart hoist: An assistive robot to aid carers.', ICARCV, International Conference on Control, Automation, Robotics and Vision, IEEE, Singapore, pp. 1285-1291.
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© 2014 IEEE. Assistive Robotics(AR) is a rapidly expanding field, implementing advanced intelligent machines capable of working collaboratively with a range of human users; as assistants, tools and as companions. These AR devices can provide assistance to stretched carers when transferring non-ambulatory patients safely. This paper presents the preliminary outcomes of the design, development and implementation of a patient lifting AR device, Smart Hoist. This device, an enhanced conventional patient lifter (standard hoist), is fitted with several sensors capable of interacting with the device operator and its environment, and a set of powered wheels. The assisted manoeuvring functionality of the Smart Hoist may help reduce prevailing lower back injuries among the carers while improving the safety of carers and patients. Results collected from an evaluation of the preliminary version of the Smart Hoist conducted at the premises of IRT Woonona residential care facility confirms the system is easy to use and it reduces the effort of the operator, which may help in reducing lower back injuries.
Roser, C, Lorentzen, K & Deuse, J 1970, 'Reliable Shop Floor Bottleneck Detection for Flow Lines through Process and Inventory Observations', Procedia CIRP, Elsevier BV, pp. 63-68.
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© 2014 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license. Bottleneck detection in manufacturing is the key to improving production efficiency and stability in order to improve capacity. Yet common bottleneck detection methods in industry and academia lack either accuracy or practicability, or both, for dynamic systems. The new methodology is conducted by the observation of processes and inventories. Blocked processes and full inventories indicate a downstream bottleneck. Starved processes and empty inventories indicate an upstream bottleneck. Through subsequent observations of multiple process states and inventory levels within a system, it is possible to determine the direction of the bottleneck at the given time and hence to find the momentary bottleneck in the system. The shifting of bottlenecks can be observed directly. Work-sampling techniques can be used to obtain a long-term picture of the dynamically shifting bottleneck. The new methodology does not require any calculations, statistics, or time measurements. Hence the method is suited for practical use by shop floor supervisors and clerks. The direct observation of the bottleneck also gives additional information about the underlying causes of the bottlenecks, simplifying the improvement of the system capacity. Extensive field testing of the method received positive feedback not only from management but also shop floor operators. The method is already in use at the Robert Bosch GmbH, where it is known as the bottleneck walk.
Ruppert, MG & Moheimani, SOR 1970, 'Novel Reciprocal Self-Sensing Techniques for Tapping-Mode Atomic Force Microscopy', IFAC Proceedings Volumes, Elsevier BV, pp. 7474-7479.
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Saha, S, Hossen, S, Hasib, MH & Saha, SC 1970, 'Onset of transition in mixed convection of a lid-driven trapezoidal enclosure filled with water-Al2O3 nanofluid', Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014.
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A numerical study is carried out to investigate the transition from laminar to chaos in mixed convection heat transfer inside a lid-driven trapezoidal enclosure. In this study, the top wall is considered as isothermal cold surface, which is moving in its own plane at a constant speed, and a constant high temperature is provided at the bottom surface. The enclosure is assumed to be filled with water-Al2O3 nanofluid. The governing Navier-Stokes and thermal energy equations are expressed in non-dimensional forms and are solved using Galerkin finite element method. Attention is paid in the present study on the pure mixed convection regime at Richandson number, Ri = 1. The numerical simulations are carried out over a wide range of Reynolds (0.1 ≤ Re ≤ 103) and Grashof (0.01 ≤ Gr ≤ 106) numbers. Effects of the presence of nanofluid on the characteristics of mixed convection heat transfer are also explored. The average Nusselt numbers of the heated wall are computed to demonstrate the influence of flow parameter variations on heat transfer. The corresponding change of flow and thermal fields is visualized from the streamline and the isotherm contour plots.
Saha, SC & Gu, YT 1970, 'Natural convection heat transfer in a baffled triangular enclosure', Proceedings of the 19th Australasian Fluid Mechanics Conference, AFMC 2014.
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To reduce the natural convection heat loss from enclosures many researchers used convection suppression devices in the past. In this study a single baffle is used under the top tip to investigate numerically the natural convection heat loss in an attic shaped enclosure which is a cost effective approach. The case considered here is one inclined wall of the enclosure is uniformly heated while the other inclined wall is uniformly cooled with adiabatic bottom wall. The finite volume method has been used to discretize the governing equations, with the QUICK scheme approximating the advection term. The diffusion terms are discretized using central-differencing with second order accuracy. A wide range of governing parameters are studied (Rayleigh number, aspect ratio, baffle length etc.). It is observed that the heat transfer due to natural convection in the enclosure reduces when the baffle length is increased. Effects of other parameters on heat transfer and flow field are described in this study.
Saha, SC, Rannie, M, Sauret, E & Gu, YT 1970, 'Numerical modelling for improved underground-mine ventilation systems', 8th Australasian Congress on Applied Mechanics, ACAM 2014, as Part of Engineers Australia Convention 2014, pp. 747-754.
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Diesel engine is commonly used in the underground mining heavy vehicle. However, particle emissions from combustion engine have been declared to be a serious concern for the human health as well as the environment. Diesel engines are one of the most important sources of particulate and NOx emissions which consumes significant amount of oxygen which is dangerous for the mine workers as they will receive insufficient oxygen supply. Therefore, we need to design a proper ventilation system so that adequate oxygen can be supplied and keep the hazardous gas or ultrafine particles concentration as an allowable level in the mining tunnels. The main objective of this study is to find a high concentration area in the mining tunnel and propose and examine various ventilation strategies to control the concentration level to ensure health and safety, work efficiency and cost related to energy consumption. The well-established computational fluid dynamics (CFD) approach has been carried out to investigate the airflow, particle tracing and the position of the ventilation system. A three dimensional unsteady model is developed in this study for an underground mine tunnel with heavy vehicle is in operation. The commercial CFD software, ANSYS 15 (CFX) has been used for the numerical simulation. An Eulerian-Lagrangian approach is used to respectively model the main flow and particules' trajectories.
Sato, H, Manabe, K-I, Wei, D, Jiang, Z & Kondo, D 1970, 'Potential of fluid pressure use for achieving high formability in micro sheet forming process', AIP Conference Proceedings, INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2014 (ICCMSE 2014), AIP Publishing LLC, Greece, pp. 327-330.
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© 2014 AIP Publishing LLC. This study decsribesa potential offluid pressure in micro hydromechanical deep drawingto achieve high formability. The FE simulation is carried out using the stainless steel foil with 50μm thickness. The friction holding effect can be obtained by applying the fluid pressure and it becomes high at high D p /t in MHDD. By applying the counter and radial pressure in MHDD, the desired lubrication condition can be obtained and the friction force can be reduced. By the friction holding effect and lubrication effect in MHDD, the micro cups can be successful fabricated in MHDD. Consequently, it is clarify that the fluid pressure has a potential to achieve the high formability because it makes the friction holding, radial pressure and lubrication effects in MHDD.
Sauret, E, Hooman, K & Saha, SC 1970, 'CFD Simulations of Flow and Heat Transfer Through the Porous Interface of a Metal Foam Heat Exchanger', Volume 1: Fuels and Combustion, Material Handling, Emissions; Steam Generators; Heat Exchangers and Cooling Systems; Turbines, Generators and Auxiliaries; Plant Operations and Maintenance; Reliability, Availability and Maintainability (RAM); Plant Systems, Structures, Components and Materials Issues, ASME 2014 Power Conference, American Society of Mechanical Engineers, Baltimore, MD.
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This paper offers numerical modelling of a waste heat recovery system. A thin layer of metal foam is attached to a cold plate to absorb heat from hot gases leaving the system. The heat transferred from the exhaust gas is then transferred to a cold liquid flowing in a secondary loop. Two different foam PPI (Pores Per Inch) values are examined over a range of fluid velocities. Numerical results are then compared to both experimental data and theoretical results available in the literature. Challenges in getting the simulation results to match those of the experiments are addressed and discussed in detail. In particular, interface boundary conditions specified between a porous layer and a fluid layer are investigated. While physically one expects much lower fluid velocity in the pores compared to that of free flow, capturing this sharp gradient at the interface can add to the difficulties of numerical simulation. The existing models in the literature are modified by considering the pressure gradient inside and outside the foam. Comparisons against the numerical modelling are presented. Finally, based on experimentally-validated numerical results, thermo-hydraulic performance of foam heat exchangers as waste heat recovery units is discussed with the main goal of reducing the excess pressure drop and maximising the amount of heat that can be recovered from the hot gas stream.
Skinner, B, Vidal-Calleja, T, Miro, JV, De Bruijn, F & Falque, R 1970, '3D point cloud upsampling for accurate reconstruction of dense 2.5D thickness maps', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, ARAA, Melbourne University.
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This paper presents a novel robust processing methodology for computing 2.5D thickness maps from dense 3D collocated surfaces. The proposed pipeline is suitable to faithfully adjust data representation detailing as required, from preserving fine surface features to coarse interpretations. The foundations of the proposed technique exploit spatial point-based filtering, ray tracing techniques and the Robust Implicit Moving Least Squares (RIMLS) algorithm applied to dense 3D datasets, such as those acquired from laser scanners. The effectiveness of the proposed technique in overcoming traditional angular aliasing and corruption artifacts is validated with 3D ranging data acquired from internal and external surfaces of exhumed water pipes. It is shown that the resulting 2.5D maps can be more accurately and completely computed to higher resolutions, while significantly reducing the number of raytracing errors when compared with 2.5D thickness maps derived from our current approach.
Tong, LY & Luo, QT 1970, 'Selection of Integral Functions for Normal Mode Analysis in Topology Optimization', Applied Mechanics and Materials, Trans Tech Publications, Ltd., pp. 795-800.
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This article investigates topology optimization for normal mode analysis using a moving iso-surface threshold method. Fundamental natural frequency needs to be calculated for many engineering structures and maximizing its value is an interesting topic in topology optimization. Optimal design for the maximum fundamental frequency may appear to be a trivial issue or impractical design. Reinforcements by introducing non-designable elements and non-structural mass or concentrated mass are often used. In this article, these issues will be solved by choosing an appropriate Φ function that is an integral function in the moving iso-surface threshold method. The proposed Φ function is expressed as strain and kinetic energy densities for a series of normal modes. By selecting the energy densities of different mode shapes, optimal topologies to maximize structural fundamental frequency are studied.
Trianni, A, Cagno, E & Farnè, S 1970, 'An Empirical Investigation of Barriers, Drivers and Practices for Energy Efficiency in Primary Metals Manufacturing SMEs', Energy Procedia, 6th International Conference on Applied Energy (ICAE), Elsevier BV, Taipei, TAIWAN, pp. 1252-1255.
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Ulapane, N, Alempijevic, A, Vidal-Calleja, T, Miro, JV, Rudd, J & Roubal, M 1970, 'Gaussian process for interpreting pulsed eddy current signals for ferromagnetic pipe profiling', 2014 9th IEEE Conference on Industrial Electronics and Applications, 2014 IEEE 9th Conference on Industrial Electronics and Applications (ICIEA), IEEE, Hangzhou, PEOPLES R CHINA, pp. 1762-1767.
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© 2014 IEEE. This paper describes a Gaussian Process based machine learning technique to estimate the remaining volume of cast iron in ageing water pipes. The method utilizes time domain signals produced by a commercially available pulsed Eddy current sensor. Data produced by the sensor are used to train a Gaussian Process model and perform inference of the remaining metal volume. The Gaussian Process model was learned using sensor data obtained from cast iron calibration plates of various thicknesses. Results produced by the Gaussian Process model were validated against the remaining wall thickness acquired using a high resolution laser scanner after the pipes were sandblasted to remove corrosion. The evaluation shows agreement between model outputs and ground truth. The paper concludes by discussing the implications or results and how the proposed method can potentially advance the current technological setup by facilitating real time pipe profiling.
Van Nguyen, L, Kodagoda, S, Ranasinghe, R & Dissanayake, G 1970, 'Spatially-distributed prediction with mobile robotic wireless sensor networks', 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), IEEE, Marina Bay Sands, Singapore, pp. 1153-1158.
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This paper presents a distributed spatial estimation and prediction approach to address the centrally-computed scheme of Gaussian Process regression at each robotic sensor in resource-constrained networks of mobile, wireless and noisy agents monitoring physical phenomena of interest. A mobile sensor independently estimate its own parameters using collective measurements from itself and local neighboring agents as they navigate through the environment. A spatially-distributed prediction algorithm is designed utilizing methods of Jacobi overrelaxation and discrete-time average consensus to enable a robotic sensor to update its estimation of obtaining the global model parameters and recursively compute the global goal of inference. A distributed navigation strategy is also considered to drive sensors to the most uncertain locations enhancing the quality of prediction and learning parameters. Experimental results in a real-world data set illustrate the effectiveness of the proposed approach and is highly comparable to those of the centralized scheme.
Van Nguyen, L, Kodagoda, S, Ranasinghe, R, Dissanayake, G, Bustamante, H, Vitanage, D & Nguyen, T 1970, 'Spatial prediction of hydrogen sulfide in sewers with a modified Gaussian process combined mutual information', 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), IEEE, Marina Bay Sands, Singapore, pp. 1130-1135.
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© 2014 IEEE. This paper proposes a data driven machine learning model for spatial prediction of hydrogen sulfide (H2S) in a gravity sewer system. The gaseous H2S in the overhead of the gravity sewer is modelled using a Gaussian Process with a new covariance function due to constraints of sewer boundaries. The covariance function is proposed based on the distance between two locations computed along the lengths of the sewer network. A mutual information based strategy is used to choose the best k sensor measurements and their locations from among n potential sensor observations and their locations. This provably NP-hard combinatorial sensor selection problem is addressed by maximizing the mutual information between the selected locations and the locations that are not selected or do not have any sensor deployments. A proof-of-concept study was carried out comparing the spatial prediction of H2S with a complex model currently used by Sydney Water. The proposed approach is shown to be effective in both modelling and predicting the H2S spatial concentrations in sewers as well as identifying optimal number of H2S sensors and their locations for a required level of prediction accuracy.
Vidal-Calleja, T, Miro, JV, Martin, F, Lingnau, DC & Russell, DE 1970, 'Automatic detection and verification of pipeline construction features with multi-modal data', 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2014), IEEE, Chicago, IL, USA, pp. 3116-3122.
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© 2014 IEEE. Assessment of the condition of underground pipelines is crucial to avoid breakages. Autonomous in-line inspection tools provided with Non-destructive Technology (NDT) sensors to assess large sections of the pipeline are commonly used for these purposes. An example of such sensors based on Eddy currents is the Remote Field Technology (RFT). A crucial step during in-line inspections is the detection of construction features, such as joints and elbows, to accurately locate and size specific defects within pipe sections. This step is often performed manually with the aid of visual data, which results in slow data processing. In this paper, we propose a generic framework to automate the detection and verification of these construction features using both NDT sensor data and visual images. Firstly, supervised learning is used to identify the construction features in the NDT sensor signals. Then, image processing is employed to verify the selection. Results are presented with data from a RFT tool, for which a specialised descriptor has been designed to characterise and classify its signal features. Furthermore, the construction feature is displayed in the image, once it is identified in the RFT data and detected in the visual data. A visual odometry algorithm has been implemented to locate the visual data with respect to the RFT data. About 800 meters of these multi-modal data are evaluated to test the validity of the proposed approach.
Vidal-Calleja, T, Su, D, De Bruijn, F & Miro, JV 1970, 'Learning spatial correlations for Bayesian fusion in pipe thickness mapping', 2014 IEEE International Conference on Robotics and Automation (ICRA), 2014 IEEE International Conference on Robotics and Automation (ICRA), IEEE, Hong Kong, pp. 1-8.
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Wallis, R, Erohin, O, Klinkenberg, R, Deuse, J & Stromberger, F 1970, 'Data Mining-supported Generation of Assembly Process Plans', Procedia CIRP, 5th CIRP Conference on Assembly Technologies and Systems (CATS), Elsevier BV, Dresden, GERMANY, pp. 178-183.
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Wallis, R, Stjepandic, J, Rulhoff, S, Stromberger, F & Deuse, J 1970, 'Intelligent utilization of digital manufacturing data in modern product emergence processes', Advances in Transdisciplinary Engineering, pp. 261-270.
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The application of digital manufacturing tools has been continuously increasing in order to deal with product and process complexity in shortened product lifecycles. The resulting comprehensive digital documentation of the product emergence process provides an opportunity to support concurrent engineering processes. By identifying correlations and recurrent patterns with the aid of data mining techniques, tacit planning knowledge can be revealed and reintegrated into new process planning workflows in order to enhance planning efficiency and facilitate decision making. Based on the classification and clustering of both product and process data and the determination of their respective linkages, this paper presents a novel approach for the knowledge-based support of product emergence processes.
Wang, Y & Huang, S 1970, 'Towards dense moving object segmentation based robust dense RGB-D SLAM in dynamic scenarios', 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), IEEE, Singapore, pp. 1841-1846.
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© 2014 IEEE. Based on the latest achievements in computer vision and RGB-D SLAM, a practical way for dense moving object segmentation and thus a new framework for robust dense RGB-D SLAM in challenging dynamic scenarios is put forward. As the state-of-the-art method in RGB-D SLAM, dense SLAM is very robust when there are motion blur or featureless regions, while most of those sparse feature-based methods could not handle them. However, it is very susceptible to dynamic elements in the scenarios. To enhance its robustness in dynamic scenarios, we propose to combine dense moving object segmentation with dense SLAM. Since the object segmentation results from the latest available algorithm in computer vision are not satisfactory, we propose some effective measures to improve upon them so that better results can be achieved. After dense segmentation of dynamic objects, dense SLAM can be employed to estimate the camera poses. Quantitative results from the available challenging benchmark dataset have proved the effectiveness of our method.
Wang, Y, Luo, Z & Zhang, N 1970, 'The topological design of materials with specified thermal expansion using a level set-based parameterization method', 11th World Congress on Computational Mechanics, WCCM 2014, 5th European Conference on Computational Mechanics, ECCM 2014 and 6th European Conference on Computational Fluid Dynamics, ECFD 2014, 11th World Congress on Computational Mechanics (WCCM) / 5th European Conference on Computational Mechanics (ECCM) / 6th European Conference on Computational Fluid Dynamics (ECFD), INT CENTER NUMERICAL METHODS ENGINEERING, Barcelona, SPAIN, pp. 625-632.
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In this paper, a level set-based parameterization method is proposed to design the three-phase composite material with specified thermal expansion coefficient. The composites are comprised by periodic base cells, and made of a three-phase material (two different material phases and a void phase). The numerical homogenization method is applied to compute effective elastic and thermal expansion properties of the composite based on a finite-element discretization of the base cell. The optimal distribution of material phases within the periodical unit cell is found using level set-based parameterization method under certain constraints, such as elastic symmetry, volume fractions of the constituent phases, and lower limit of bulk modulus. A MATLAB program is developed to conduct the composite material design and the results demonstrate that materials with zero and negative effective thermal expansion coefficients can be achieved by three-phase materials.
Ward, PK, Manamperi, P, Brooks, P, Mann, P, Kaluarachchi, W, Matkovic, L, Paul, G, Yang, C, Quin, P, Pagano, D, Liu, D, Waldron, K & Dissanayake, G 1970, 'Climbing Robot for Steel Bridge Inspection: Design Challenges', Proceedings for the Austroads Publications Online, Austroads Bridge Conference, ARRB Group, New South Wales, pp. 1-13.
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Inspection of bridges often requires high risk operations such as working at heights, in confined spaces, in hazardous environments; or sites inaccessible by humans. There is significant motivation for robotic solutions which can carry out these inspection tasks. When inspection robots are deployed in real world inspection scenarios, it is inevitable that unforeseen challenges will be encountered.Since 2011, the New South Wales Roads & Maritime Services and the Centre of Excellence for Autonomous Systems at the University of Technology, Sydney, have been working together to develop an innovative climbing robot to inspect high risk locations on the Sydney Harbour Bridge. Many engineering challenges have been faced throughout the development of several prototype climbing robots, and through field trials in the archways of the Sydney Harbour Bridge. This paper will highlight some of the key challenges faced in designing a climbing robot for inspection, and then present an inchworm inspired robot which addresses many of these challenges.
Williams, PT & Kirby, R 1970, 'The effect of higher order modes on the performance of large diameter dissipative silencers', Proceedings of Forum Acusticum, Forum Acusticum, Krakow, Poland.
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Within the gas turbine industry dissipative silencers are regularly used to reduce broadband noise within duct systems. Silencer performance is normally quantified using the insertion loss due to a plane wave incident sound field. However for larger silencers the widths of these duct systems are large enough to allow higher order modes to propagate over much of the frequency range of interest (31-8kHz octave bands), which may have a significant effect upon silencer performance that is not normally accounted for. The performance of dissipative parallel baffle and bar silencers in the presence of different types of incident sound field is investigated through a numerical model which uses the finite element method and point collocation to predict insertion loss. Excitation of the silencer using an equal modal energy density sound field is found to have a large effect upon performance compared to plane wave excitation. Increases to insertion loss are predicted at high frequencies for the geometries modelled and it is found that plane wave predictions do not necessarily give the worst case performance.
Wu, K, Ranasinghe, R & Dissanayake, G 1970, 'A fast pipeline for textured object recognition in clutter using an RGB-D sensor', 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), IEEE, Marina Bay Sands, Singapore, pp. 1650-1655.
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This paper presents a modular algorithm pipeline for recognizing textured household objects in cluttered environment and estimating 6 DOF poses using an RGB-D sensor. The method draws from recent advances in this area and introduces a number of innovations that enable improved performances and faster operational speed in comparison with the state-of-the-art. The pipeline consists of (i) support plane subtraction (ii) SIFT feature extraction and approximate nearest neighbour based
matching (iii) feature clustering using 3D Eculidean distances (iv) SVD based pose estimation in combination with a outlier rejection strategy named SORSAC ( Spatially ORdered RAndom Consensus ) and (v) a pose combination and refinement step to
combine overlapping identical instances and to refine the pose estimation result by removing incorrect hypothesis. Quantitative comparisons with the MOPED [1] system on self-constructed dataset are presented to demonstrate the effectiveness of the pipeline.
Zhang, T, Huang, S & Liu, D 1970, 'Comparison of two strategies of path planning for underwater robot navigation under uncertainty', 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), 2014 13th International Conference on Control Automation Robotics & Vision (ICARCV), IEEE, Singapore, pp. 901-906.
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© 2014 IEEE. This paper considers path planning for underwater robot in navigation tasks. The main challenge is how to deal with uncertainties in the underwater environment such as motion model error and sensing error. To overcome this challenge, two high level control methods have been presented and compared, which are based on the Model Predictive Control (MPC) strategy and the Partially Observable Markov Decision Process (POMDP) model, respectively. Navigation time, collision frequency, energy consumption and accuracy in localization are used as the assessment criteria for the two methods. It is shown that the MPC-based method is more efficient for our application scenarios while the POMDP-based method can provide more robust solutions.
Zhang, T, Huang, S & Liu, D 1970, 'Comparison of Two Strategies of Path Planning for Underwater Robot Navigation Under Uncertainty', 2014 13TH INTERNATIONAL CONFERENCE ON CONTROL AUTOMATION ROBOTICS & VISION (ICARCV), 13th International Conference on Control Automation Robotics & Vision (ICARCV), IEEE, Singapore, SINGAPORE, pp. 901-906.
Zhang, Z, Oberst, S & Lai, JCS 1970, 'A stochastic approach to predicting brake squeal propensity', 21st International Congress on Sound and Vibration 2014, ICSV 2014, 21st International Congress on Sound and Vibration 2014, ICSV 2014, pp. 629-636.
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Brake squeal as a significant noise, vibration and harshness (NVH) issue to the automotive industry is triggered by friction-induced self-excited vibration. Validating theoretical predictions using analytical or numerical models against experiments is difficult because the test results are often not repeatable even under apparently similar operating conditions. The poor repeatability of brake squeal could be attributed to the nonlinearity of the dynamics involved and the uncertainties associated with material properties, boundary conditions (such as contact pressure, temperature, stiffness, exact area of contact) and operating conditions. In this paper, a stochastic approach to predicting brake squeal propensity is examined using an analytical model of a popular 4-DOF friction oscillator with constant friction coefficient. Instability of this model is first estimated using the conventional linear complex eigenvalue analysis (CEA) and compared with calculations of positive friction work. The sensitivity of this deterministic model to variations of parameters such as spring stiffness and damping coefficient is studied. To account for uncertainties in the exact values of parameters, the analytical model is studied using polynomial chaos expansions with beta distribution on a set of Jacobi polynomials. Probabilities for instabilities based on positive friction work are determined and the implications for estimating squeal propensity in a full brake system are discussed.
Zhang, Z, Oberst, S & Lai, JCS 1970, 'Instability prediction of brake squeal by nonlinear stability analysis', INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control, INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control.
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Prediction of brake squeal as unwanted high frequency noise above 1 kHz remains a challenging problem despite substantial research efforts in the past two decades. Brake squeal, triggered by friction-induced self-excited vibration, can be caused by many different and interacting mechanisms with nonlinear origins in material properties and boundary conditions. Although brake squeal is essentially a nonlinear phenomenon, the standard industrial practice for prediction of brake squeal relies on the linear complex eigenvalue analysis which may under-predict or over-predict the number of unstable vibration modes. Brake squeal can be considered in nonlinear dynamics terms to be caused by a friction-induced self-excitation driven into instability and oscillating in a limit cycle through super-critical Andronov-Hopf bifurcations. In this paper, a nonlinear stability analysis that may be applied to a full brake system is examined using an unforced 4-DOF friction oscillator with cubic nonlinearity. The local bifurcation behaviour of this model is studied using the normal form theory and the nonlinear stability boundary is evaluated. Differences between results of linear and nonlinear analyses are discussed and the limitations of the linear analysis are highlighted. The energy provided by friction and consumed by damping is calculated by multiple scales method to provide a physical explanation for instability generation.
Zhao, L, Huang, S & Dissanayake, G 1970, 'Linear MonoSLAM: A linear approach to large-scale monocular SLAM problems', 2014 IEEE International Conference on Robotics and Automation (ICRA), 2014 IEEE International Conference on Robotics and Automation (ICRA), IEEE, Hong Kong, China, pp. 1517-1523.
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© 2014 IEEE. This paper presents a linear approach for solving monocular simultaneous localization and mapping (SLAM) problems. The algorithm first builds a sequence of small initial submaps and then joins these submaps together in a divide-and-conquer (D&C) manner. Each of the initial submap is built using three monocular images by bundle adjustment (BA), which is a simple nonlinear optimization problem. Each step in the D&C submap joining is solved by a linear least squares together with a coordinate and scale transformation. Since the only nonlinear part is in the building of the initial submaps, the algorithm makes it possible to solve large-scale monocular SLAM while avoiding issues associated with initialization, iteration, and local minima that are present in most of the nonlinear optimization based algorithms currently used for large-scale monocular SLAM. Experimental results based on publically available datasets are used to demonstrate that the proposed algorithms yields solutions that are very close to those obtained using global BA starting from good initial guess.
Zhao, S, Qiu, X & Lu, J 1970, 'Curving sound field reproduction in free field', 21st International Congress on Sound and Vibration 2014, ICSV 2014, 21st International Congress on Sound and Vibration 2014, pp. 2297-2304.
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Curving sound field reproduction refers to recreating sound propagating along a curving trajectory without disturbing the other side. This kind of sound could bypass the obstacle to reach the region behind the obstacle, which is difficult for conventional sound field reproduction system. Curving sound field reproduction can find applications in various situations, for example, speech signal could be delivered to a person without disturbing another person in front of him/her. This paper investigates the mechanisms for generating sound field based on the wave equation and the spatial sampling theory and the method of using linear loudspeaker arrays to generate such a sound field. A method based on ray acoustics to determine the loudspeaker weights is proposed and the simulation results are in good agreement with the theory. Extension to wideband situation of the method is also investigated and proved to be effective in a broad range of frequencies covering the human speech signal spectrum from 300 Hz to 3400 Hz.
