Abdo, P & Huynh, BP 2021, 'An experimental investigation of green wall bio-filter towards air temperature and humidity variation', Journal of Building Engineering, vol. 39, pp. 102244-102244.
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Green walls show promise in providing thermal comfort. Their benefits include the reduction of the temperature of air layers around them. They are classified as passive and active systems. Active systems are designed with ventilators that force air through the substrate and plant rooting system of the green wall. With a passive system, air is simply diffused through the green wall substrate and the plant foliage. The current work investigates the effect of green walls on the air temperature and humidity. Temperature and humidity are measured at different locations inside an acrylic chamber where different modules with different plant species are placed. The effect of changing the surrounding ambient conditions is also investigated. Experiments lasted at least 24 h to cover day and night time conditions. For the active modules, lower temperatures in the range of 1–3 °C, along with increased humidity levels have been observed when modules are saturated wet. Passive modules have also provided lower temperatures in the range of 0.5–2 °C. None of the plant species studied showed any preference, indicating that the moisture content of the substrate plays the major role affecting the temperature and humidity variations.
Ahmed, SF, Saha, SC, Debnath, JC, Liu, G, Mofijur, M, Baniyounes, A, Chowdhury, SMEK & Vo, D-VN 2021, 'Data-driven modelling techniques for earth-air heat exchangers to reduce energy consumption in buildings: a review', Environmental Chemistry Letters, vol. 19, no. 6, pp. 4191-4210.
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Increasing population and urbanization call for smarter cities where the cycles of matter and energy are optimized, notably in buildings which are actually a source of pollution consuming a lot of energy. The efficiency of building energy has been improved by modelling earth-air heat exchangers, yet selecting the suitable models is challenging. Here we review data-driven earth-air heat exchanger models used for buildings. We discuss issues brought about by assumptions, unmeasured disruptions, and uncertainties in numerical and experimental works. We found that high accuracy can be reached if sufficient data is available. Models are appropriate for real-time activity due to their structure simplicity, yet they display a poor generalization capacity. Model development is limited by the constrained parameters and the complex boundary conditions of the heat exchangers.
Ahmed, T, Hassan, S, F. Hasan, M, M. Molla, M, A. Taher, M & C. Saha, S 2021, 'Lattice Boltzmann Simulation of Magnetic Field Effect on ElectricallyConducting Fluid at Inclined Angles in Rayleigh-B閚ard Convection', Energy Engineering, vol. 118, no. 1, pp. 15-36.
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Al zahrani, S, Islam, MS & Saha, SC 2021, 'Heat transfer enhancement investigation in a novel flat plate heat exchanger', International Journal of Thermal Sciences, vol. 161, pp. 106763-106763.
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Al zahrani, S, Islam, MS & Saha, SC 2021, 'Heat transfer enhancement of modified flat plate heat exchanger', Applied Thermal Engineering, vol. 186, pp. 116533-116533.
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Alempijevic, A, Vidal-Calleja, T, Falque, R, Quin, P, Toohey, E, Walmsley, B & McPhee, M 2021, 'Lean meat yield estimation using a prototype 3D imaging approach', Meat Science, vol. 181, pp. 108470-108470.
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Alfouneh, M, Ji, J & Luo, Q 2021, 'Damping design of harmonically excited flexible structures with graded materials to minimize sound pressure and radiation', Engineering Optimization, vol. 53, no. 2, pp. 348-367.
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© 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group. Topology optimization is an effective method in the design of acoustic media. This article presents optimization for graded damping materials to minimize sound pressure at a reference point or sound power radiation under harmonic excitation. The Helmholtz integral equation is used to calculate an acoustic field to satisfy the Sommerfeld conditions. The equation of motion is solved using a unit dynamic load method. Formulations for the sound pressure or sound power radiation in an integral form are derived in terms of mutual kinetic and strain energy densities. These integrals lead to novel physical response functions for solving the proposed optimization problem to design graded damping materials. The response function derived for individual frequency is utilized to solve the multi-objective optimization problem of minimizing sound pressure at the reference point for excitations with a range of frequencies. Numerical examples are presented to verify the efficiency of the present formulations.
Almotairy, SM, Boostani, AF, Hassani, M, Wei, D & Jiang, ZY 2021, 'Mechanical Properties of Aluminium Metal Matrix Nanocomposites Manufactured by Assisted-Flake Powder Thixoforming Process', Metals and Materials International, vol. 27, no. 5, pp. 851-859.
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© 2019, The Korean Institute of Metals and Materials. Abstract: This study discusses the superior effect of thixoforming process on enhancing the tensile properties of aluminium matrix composite produced using flake metallurgy route. The flake metallurgy process was utilised to manufacture aluminium matrix composites followed by thixoforming process. Microstructural investigations carried out using transmission electron microscope have shown the synergic effect of thixoforming process on rendering uniform distribution of SiC nanoparticles associated with lower porosity content. X-ray diffraction characterisations have revealed the promising effect of uniform dispersion of SiC nanoparticles on restricting the grain growth of aluminium matrix within nanoscale regime (90 nm) even at high semi-solid thixoforming temperatures (575 °C). The achieved results of tensile tests have shown a profound effect of flake metallurgy of aluminium powder through dual speed ball milling. These results are higher than those achieved by low speed and high speed even with higher SiC content. This was attributed to the uniform confinement of SiC nanoparticles within the samples produced using flake-assisted forming process compared to the ones manufactured using ball milling-assisted processes. Graphic abstract: [Figure not available: see fulltext.].
Al-Zahrani, S, Islam, MS & Saha, SC 2021, 'Comparison of flow resistance and port maldistribution between novel and conventional plate heat exchangers', International Communications in Heat and Mass Transfer, vol. 123, pp. 105200-105200.
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Arqam, M, Dao, DV, Mitchell, M & Woodfield, P 2021, 'Transient start-up of an electric swashplate refrigeration compressor', Applied Thermal Engineering, vol. 196, pp. 117351-117351.
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Azzam, R, Alkendi, Y, Taha, T, Huang, S & Zweiri, Y 2021, 'A Stacked LSTM-Based Approach for Reducing Semantic Pose Estimation Error', IEEE Transactions on Instrumentation and Measurement, vol. 70, pp. 1-14.
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© 1963-2012 IEEE. Achieving high estimation accuracy is significant for semantic simultaneous localization and mapping (SLAM) tasks. Yet, the estimation process is vulnerable to several sources of error, including limitations of the instruments used to perceive the environment, shortcomings of the employed algorithm, environmental conditions, or other unpredictable noise. In this article, a novel stacked long short-term memory (LSTM)-based error reduction approach is developed to enhance the accuracy of semantic SLAM in presence of such error sources. Training and testing data sets were constructed through simulated and real-time experiments. The effectiveness of the proposed approach was demonstrated by its ability to capture and reduce semantic SLAM estimation errors in training and testing data sets. Quantitative performance measurement was carried out using the absolute trajectory error (ATE) metric. The proposed approach was compared with vanilla and bidirectional LSTM networks, shallow and deep neural networks, and support vector machines. The proposed approach outperforms all other structures and was able to significantly improve the accuracy of semantic SLAM. To further verify the applicability of the proposed approach, it was tested on real-time sequences from the TUM RGB-D data set, where it was able to improve the estimated trajectories.
Barani, A, Mosaddegh, P, Haghjooy Javanmard, S, Sepehrirahnama, S & Sanati-Nezhad, A 2021, 'Numerical and experimental analysis of a hybrid material acoustophoretic device for manipulation of microparticles', Scientific Reports, vol. 11, no. 1.
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AbstractAcoustophoretic microfluidic devices have been developed for accurate, label-free, contactless, and non-invasive manipulation of bioparticles in different biofluids. However, their widespread application is limited due to the need for the use of high quality microchannels made of materials with high specific acoustic impedances relative to the fluid (e.g., silicon or glass with small damping coefficient), manufactured by complex and expensive microfabrication processes. Soft polymers with a lower fabrication cost have been introduced to address the challenges of silicon- or glass-based acoustophoretic microfluidic systems. However, due to their small acoustic impedance, their efficacy for particle manipulation is shown to be limited. Here, we developed a new acoustophoretic microfluid system fabricated by a hybrid sound-hard (aluminum) and sound-soft (polydimethylsiloxane polymer) material. The performance of this hybrid device for manipulation of bead particles and cells was compared to the acoustophoretic devices made of acoustically hard materials. The results show that particles and cells in the hybrid material microchannel travel to a nodal plane with a much smaller energy density than conventional acoustic-hard devices but greater than polymeric microfluidic chips. Against conventional acoustic-hard chips, the nodal line in the hybrid microchannel could be easily tuned to be placed in an off-center position by changing the frequency, effective for particle separation from a host fluid in parallel flow stream models. It is also shown that the hybrid acoustophoretic device deals with smaller temperature rise which is safer for the actuation of bioparticles. This new device eliminates the limitations of each sound-soft and sound-hard materials in terms of cost, adjusting the position of nodal plane, temperature rise, fragility, production cost and disposability, making it desirable for developing the next gene...
C. Saha, S, M. Sefidan, A, Sojoudi, A & M. Molla, M 2021, 'Transient Free Convection and Heat Transfer in a Partitioned Attic-Shaped Space under Diurnal Thermal Forcing', Energy Engineering, vol. 118, no. 3, pp. 487-506.
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Cetindamar, D, Lammers, T, Kocaoglu, DF & Zhang, Y 2021, 'The Anniversary Tribute of PICMET: 1989-2018.', IEEE Trans. Engineering Management, vol. 68, no. 2, pp. 612-627.
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The Portland International Conference for Management
of Engineering and Technology (PICMET) has become a
world-leading organization in the field of management of engineering
and technology management (MET) since its inception in
1989. PICMET provides a strong platform for academics, industry
professionals, and government representatives to exchange new
knowledge in the field. To celebrate its 30-year journey, this article
examines 20 conferences organized by PICMET covering 6601
accepted papers in order to show the trends in MET research and
implementation through topics, authors, journals, and countries. In
addition to the analysis of the PICMET data, the article delves into
the past ten years (2009–2018) to carry out an in-depth bibliometric
analysis of the citations of more than 3000 PICMET papers available
at Scopus. The detailed analysis sheds light on how PICMET
has developed a rich network of researchers and practitioners
through its conferences over time. PICMET contributes to the
interdisciplinary nature of the MET field and is also affected by
the changes of the field. The article ends with key observations and
a few suggestions for further studies.
Chen, R, Yin, H, Jiao, Y, Dissanayake, G, Wang, Y & Xiong, R 2021, 'Deep Samplable Observation Model for Global Localization and Kidnapping', IEEE Robotics and Automation Letters, vol. 6, no. 2, pp. 2296-2303.
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Chen, Y, Huang, S, Zhao, L & Dissanayake, G 2021, 'Cramér–Rao Bounds and Optimal Design Metrics for Pose-Graph SLAM', IEEE Transactions on Robotics, vol. 37, no. 2, pp. 627-641.
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Two-dimensional (2-D)/3-D pose-graph simultaneous localization and mapping (SLAM) is a problem of estimating a set of poses based on noisy measurements of relative rotations and translations. This article focuses on the relation between the graphical structure of pose-graph SLAM and Fisher information matrix (FIM), Cramér–Rao lower bounds (CRLB), and its optimal design metrics (T-optimality and D-optimality). As a main contribution, based on the assumption of isotropic Langevin noise for rotation and block-isotropic Gaussian noise for translation, the FIM and CRLB are derived and shown to be closely related to the graph structure, in particular, the weighted Laplacian matrix. We also prove that total node degree and weighted number of spanning trees, as two graph connectivity metrics, are, respectively, closely related to the trace and determinant of the FIM. The discussions show that, compared with the D-optimality metric, the T-optimality metric is more easily computed but less effective. We also present upper and lower bounds for the D-optimality metric, which can be efficiently computed and are almost independent of the estimation results. The results are verified with several well-known datasets, such as Intel, KITTI, sphere, and so on.
Chiang, YK, Quan, L, Peng, Y, Sepehrirahnama, S, Oberst, S, Alù, A & Powell, DA 2021, 'Scalable Metagrating for Efficient Ultrasonic Focusing', Physical Review Applied, vol. 16, no. 6, pp. 1-9.
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Acoustic metalenses have been pursued over the past decades due to their pivotal role in a wide variety of applications. Recent research efforts have demonstrated that, at ultrasonic regimes, acoustic levitation can be realized with standing waves, which are created by the interference between incoming and reflected focused waves. However, the conventional gradient-metasurface approach to focus ultrasonic waves is complex, leading to poor scalability. In this work, we propose a design principle for ultrasonic metalenses, based on metagratings - arrays of discrete scatters with coarser features than gradient metasurfaces. We achieve beam focusing by locally controlling the excitation of a single diffraction order with the use of metagratings, with geometry adiabatically varying over the lens aperture. We show that our metalens can effectively focus impinging ultrasonic waves to a focal point with a full width at half maximum of 0.364 of the wavelength. The focusing performance of the metalens is demonstrated experimentally, validating our proposed approach. This metagrating approach to focusing can be adopted for different operating frequencies by scaling the size of the structure, which has coarse features suitable for high-frequency designs, with potential applications ranging from biomedical science to nondestructive testing.
Cullen, M, Zhao, S, Ji, J & Qiu, X 2021, 'Classification of transfer modes in gas metal arc welding using acoustic signal analysis', The International Journal of Advanced Manufacturing Technology, vol. 115, no. 9-10, pp. 3089-3104.
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Gas metal arc welding (GMAW) is a welding process in which an electric arc is formed between a wire electrode and a metal workpiece alongside a shielding gas to protect the arc from contaminants. There are several ways in which the molten electrode droplet can be transferred to the weld pool known as metal transfer modes. Identifying the metal transfer mode automatically is essential to monitor and control the welding process, especially in automated processes employed in modern Industry 4.0 manufacturing lines. However, limited research on this topic has been found in literature. This paper explores the automatic classification of metal transfer modes in GMAW based on machine learning techniques with various signals from the welding process, including acoustics, current, voltage and gas flow rate signals. Time and frequency domain features are first extracted from these signals and are used in a support vector machine classifier to detect the metal transfer modes. A feature selection algorithm is proposed to improve the prediction rate from 80 to 99% when all four signals are utilised. When only the non-intrusive acoustic signal is used, the prediction rates with and without the proposed feature selection algorithm are approximately 96% and 81%, respectively. The high prediction rate demonstrates the feasibility and promising accuracy of the acoustic signal–based classification method for future smart welding technology with real-time adaptive feedback control of the welding process.
Datz, J, Karimi, M & Marburg, S 2021, 'Effect of Uncertainty in the Balancing Weights on the Vibration Response of a High-Speed Rotor', Journal of Vibration and Acoustics, vol. 143, no. 6, pp. 1-12.
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Abstract This work investigates how uncertainties in the balancing weights are propagating into the vibration response of a high-speed rotor. Balancing data are obtained from a 166-MW gas turbine rotor in a vacuum balancing tunnel. The influence coefficient method is then implemented to characterize the rotor system by a deterministic multi-speed and multi-plane matrix. To model the uncertainties, a non-sampling probabilistic method based on the generalized polynomial chaos expansion (gPCE) is employed. The uncertain parameters including the mass and angular positions of the balancing weights are then expressed by gPCE with deterministic coefficients. Assuming predefined probability distributions of the uncertain parameters, the stochastic Galerkin projection is applied to calculate the coefficients for the input parameters. Furthermore, the vibration amplitudes of the rotor response are represented by appropriate gPCE with unknown deterministic coefficients. These unknown coefficients are determined using the stochastic collocation method by evaluating the gPCE for the system response at a set of collocation points. The effects of individual and combined uncertain parameters from a single and multiple balancing planes on the rotor vibration response are examined. Results are compared with the Monte Carlo simulations, showing excellent agreement.
Dombrowski, U, Deuse, J, Ortmeier, C, Henningsen, N, Wullbrandt, J & Nöhring, F 2021, 'Auswahlsystematik für Methoden und Werkzeuge Ganzheitlicher Produktionssysteme 4.0', Zeitschrift für wirtschaftlichen Fabrikbetrieb, vol. 116, no. 6, pp. 398-402.
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Abstract Das produzierende Gewerbe steht aktuell vor der Herausforderung, bestehende Produktionssysteme mit Industrie-4.0-Lösungen zu erweitern, um deren Potenziale zu nutzen und somit die Wettbewerbsfähigkeit zu sichern. Es fehlen insbesondere kleinen und mittleren Unternehmen (KMU) jedoch die Transparenz über die Wirkung und die Auswahl von Industrie-4.0-Lösungen. Im Rahmen des Forschungsprojekts „Ganzheitliche Produktionssysteme 4.0“ (GaProSys 4.0) wurde diese Problematik aufgegriffen. In diesem Beitrag werden die Vorgehensweise zur Entwicklung von GaProSys-4.0-Methoden anhand des elektronischen Shopfloor Managements aufgezeigt und die im Rahmen des Forschungsprojektes erarbeitete Auswahlsystematik präsentiert.
Eager, D, Chapman, C, Qi, Y, Ishac, K & Hossain, MI 2021, 'Additional Criteria for Playground Impact Attenuating Sand', Applied Sciences, vol. 11, no. 19, pp. 8805-8805.
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Falls within children’s playgrounds result in long bone and serious injuries. To lower the likelihood and severity of injury, impact attenuating surfaces (IAS) are installed within the impact area (fall zone). There are three primary IAS materials used, namely: granulated rubber products, wood fibre products, and sand. There is a deficiency with existing IAS test methods in that they do not take account of sand degradation over time. When children use the playground, sand degradation can occur when sand produces fines and smaller particles with low sphericity and angular which fill the voids between the sand particles. These fines and smaller particles tend to bind the sand and lower its impact attenuating performance. This paper proposes an additional IAS test to eliminate sands that degrade above an established threshold rate after installation due to normal usage. IAS degradation properties of fifteen IAS sands were tested including sand particle shape, sand particle distribution, percentage fines and sand particle degradation. This accelerated ageing test method is applicable only to sands and not rubber or wood fibre IAS products. The best IAS sands were sourced from quarries located on rivers that had eroded volcanic outcrops. These sands were shown to degrade the least and had little to no fines, and their particle shape was rounded to well-rounded. The most reliable source for good quality IAS sands on these rivers was on specific bends. The sand mined at these locations consistently had a tight particle size distribution.
Eager, D, Halkon, B, Zhou, S, Walker, P, Covey, K & Braiden, S 2021, 'Greyhound Racing Track Lure Systems—Acoustical Measurements within and Adjacent to the Starting Boxes', Technologies, vol. 9, no. 4, pp. 74-74.
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This study investigates and compares the acoustic signatures of a traditional wire-cable-pulled lure system and two alternative battery-operated lure systems jointly developed by Covey Associates Pty. Ltd. and Steriline Pty. Ltd. to eliminate the hazardous steel-wire cable and make the sport of greyhound racing safer for greyhounds, participants and spectators. The acoustical measurements of these three lure systems were conducted at the Murray Bridge greyhound racing track. The lure sounds were measured by the high-frequency Brüel & Kjær (B&K) Type 4191 microphones for the 395 m and 455 m starts at two positions: within the starting box and on the track adjacent to the starting boxes. The measurements capture the sounds that the greyhounds hear before and after the opening of the starting box gate. The frequency-domain analysis and sound quality analysis were conducted to compare the lure sounds. It was found when the battery-lure was installed with all nylon rollers, it presented less sound energy and lower frequency than the traditional wire-cable-pulled lure. When two of the nylon rollers were replaced with steel rollers, the battery-operated lure emitted a louder and higher frequency sound than the traditional wire-cable-pulled lure. The different acoustic characteristics of these lure systems suggest future research is warranted on the reaction of greyhounds to different lure sounds, particularly their excitement level within the starting box as the lure approaches. This initial research also suggests some greyhounds may not clearly hear the battery-operated lure with all nylon rollers approaching the starting boxes and the timing of these greyhounds to jump may be delayed, particularly during high wind conditions.
Eager, D, Hossain, I, Ishac, K & Robins, S 2021, 'Analysis of Racing Greyhound Path Following Dynamics Using a Tracking System', Animals, vol. 11, no. 9, pp. 2687-2687.
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The University of Technology Sydney (UTS) has been working closely with the Australasian greyhound industry for more than 5 years to reduce greyhound race-related injuries. During this period, UTS has developed and deployed several different techniques including inertial measurement units, drones, high-frame-rate cameras, track geometric surveys, paw print analysis, track soil spring-force analysis, track maintenance data, race injury data, race computer simulation and modelling to assist in this task. During the period where the UTS recommendations have been adopted, the injury rate has dropped significantly. This has been achieved by animal welfare interventions that lower racing congestion, and lower transient forces and jerk rates the greyhounds experience during a race. This study investigated the use of a greyhound location tracing system where small and lightweight signal emitting devices were placed inside a pocket in the jackets of racing greyhounds. The system deployed an enhanced version of a player tracking system currently used to track the motion of human athletes. Greyhounds gallop at speeds of almost 20 m/s and are known to change their heading direction to exceed a yaw rate of 0.4 rad/s. The high magnitudes of velocity, acceleration and jerk posed significant technical challenges, as the greyhounds pushed the human tracking system beyond its original design limits. Clean race data gathered over a six-month period were analysed and presented for a typical 2-turn greyhound racing track. The data confirmed that on average, greyhounds ran along a path that resulted in the least energy wastage, which includes smooth non-linear paths that resemble easement curves at the transition between the straights to the semi-circular bends. This study also verified that the maximum jerk levels greyhounds experienced while racing were lower than the jerk levels that had been predicted with simulations and modelling for the track path. Furthermore...
Fan, Z, Holmes, DW, Sauret, E, Islam, MS, Saha, SC, Ristovski, Z & Gu, Y 2021, 'A multiscale modeling method incorporating spatial coupling and temporal coupling into transient simulations of the human airways', International Journal for Numerical Methods in Fluids, vol. 93, no. 9, pp. 2905-2920.
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AbstractIn this article, a novel multiscale modeling method is proposed for transient computational fluid dynamics (CFD) simulations of the human airways. The developed method is the first attempt to incorporate spatial coupling and temporal coupling into transient human airway simulations, aiming to improve the flexibility and the efficiency of these simulations. In this method, domain decomposition was used to separate the complex airway model into different scaled domains. Each scaled domain could adopt a suitable mesh and timestep, as necessary: the coarse mesh and large timestep were employed in the macro regions to reduce the computational cost, while the fine mesh and small timestep were used in micro regions to maintain the simulation accuracy. The radial point interpolation method was used to couple data between the coarse mesh and the fine mesh. The continuous micro solution–intermittent temporal coupling method was applied to bridge different timesteps. The developed method was benchmarked using a well‐studied four‐generation symmetric airway model under realistic normal breath conditions. The accuracy and efficiency of the method were verified separately in the inhalation phase and the exhalation phase. Similar airflow behavior to previous studies was observed from the multiscale airway model. The developed multiscale method has the potential to improve the flexibility and efficiency of transient human airway simulations without sacrificing accuracy.
Feng, Y, Wang, Q, Wu, D, Luo, Z, Chen, X, Zhang, T & Gao, W 2021, 'Machine learning aided phase field method for fracture mechanics', International Journal of Engineering Science, vol. 169, pp. 103587-103587.
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Geissinger, A, Laurell, C, Öberg, C, Sandström, C, Sick, N & Suseno, Y 2021, 'Social media analytics for knowledge acquisition of market and non-market perceptions in the sharing economy', Journal of Knowledge Management, vol. 25, no. 2, pp. 500-512.
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PurposeUsing the case of Foodora, this paper aims to assess the impact of technological innovation of an emerging actor in the sharing economy through stakeholders’ perceptions in the market and non-market domains.Design/methodology/approachUsing a methodological approach called social media analytics (SMA) to explore the case of Foodora, 3,250 user-generated contents in social media are systematically gathered, coded and analysed.FindingsThe findings indicate that, while Foodora appears to be a viable provider in the marketplace, there is mounting public concern about the working conditions of its employees. In the market domain, Foodora manages its status as an online delivery platform and provider well, but at the same time, it struggles with its position in the non-market sphere, suggesting that the firm is vulnerable to regulatory change. These insights highlight the importance of simultaneously exploring and balancing market and non-market perceptions when assessing the impact of disruptive innovation.Originality/valueThis study offers originality by providing an integrative approach to consider both the market and non-market domains. It is also novel in its use of SMA as a tool for knowledge acquisition and management to evaluate the impact of emerging technologies in the sharing economy.
Ghalambaz, M, Mehryan, SAM, Ayoubi Ayoubloo, K, Hajjar, A, Islam, MS, Younis, O & Aly, AM 2021, 'Thermal behavior and energy storage of a suspension of nano-encapsulated phase change materials in an enclosure', Advanced Powder Technology, vol. 32, no. 6, pp. 2004-2019.
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Ghalambaz, M, Mohammed, HI, Naghizadeh, A, Islam, MS, Younis, O, Mahdi, JM, Chatroudi, IS & Talebizadehsardari, P 2021, 'Optimum Placement of Heating Tubes in a Multi-Tube Latent Heat Thermal Energy Storage', Materials, vol. 14, no. 5, pp. 1232-1232.
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Utilizing phase change materials in thermal energy storage systems is commonly considered as an alternative solution for the effective use of energy. This study presents numerical simulations of the charging process for a multitube latent heat thermal energy storage system. A thermal energy storage model, consisting of five tubes of heat transfer fluids, was investigated using Rubitherm phase change material (RT35) as the. The locations of the tubes were optimized by applying the Taguchi method. The thermal behavior of the unit was evaluated by considering the liquid fraction graphs, streamlines, and isotherm contours. The numerical model was first verified compared with existed experimental data from the literature. The outcomes revealed that based on the Taguchi method, the first row of the heat transfer fluid tubes should be located at the lowest possible area while the other tubes should be spread consistently in the enclosure. The charging rate changed by 76% when varying the locations of the tubes in the enclosure to the optimum point. The development of streamlines and free-convection flow circulation was found to impact the system design significantly. The Taguchi method could efficiently assign the optimum design of the system with few simulations. Accordingly, this approach gives the impression of the future design of energy storage systems.
Gharleghi, R, Wright, H, Luvio, V, Jepson, N, Luo, Z, Senthurnathan, A, Babaei, B, Prusty, BG, Ray, T & Beier, S 2021, 'A multi-objective optimization of stent geometries', Journal of Biomechanics, vol. 125, pp. 110575-110575.
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Guertler, MR & Sick, N 2021, 'Exploring the enabling effects of project management for SMEs in adopting open innovation – A framework for partner search and selection in open innovation projects', International Journal of Project Management, vol. 39, no. 2, pp. 102-114.
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© 2020 Open Innovation (OI) facilitates a multitude of innovation opportunities through allowing access to a broad variety of external partners, expertise and knowledge. Although OI has been established in academia and the corporate world, implementation by SMEs remains a formidable challenge, especially concerning the identification and selection of suitable OI partners. Given methodical support for such an endeavour is currently lacking, this article investigates how project management can support OI projects. Based on evidence from an exploratory multi-case study with four SMEs, this article develops a Situational Open Innovation framework that provides methodical support for SMEs in leveraging the complementarities between OI and project management towards effective partner search and selection. The findings illustrate how sensing capabilities for OI opportunities can benefit from systematic problem and stakeholder analyses as they allow for identifying and focussing on the most relevant innovation tasks and partners.
Gunatilake, A, Piyathilaka, L, Tran, A, Vishwanathan, VK, Thiyagarajan, K & Kodagoda, S 2021, 'Stereo Vision Combined With Laser Profiling for Mapping of Pipeline Internal Defects', IEEE Sensors Journal, vol. 21, no. 10, pp. 11926-11934.
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Underground potable water pipes are essential infrastructure assets for any country. A significant proportion of those assets are deteriorating due to pipe corrosion which results in premature failure of pipes causing enormous disruptions to the public and loss to the economy. To address such adverse effects, the water utilities in Australia exploit advanced pipelining technologies with a motive of extending the service life of their pipe assets. However, the linings are prone to defects due to improper liner application and unfavorable environmental conditions during the liner curing phase. To monitor the imperfections of the pipe linings, in this article, we propose a mobile robotic sensing system that can scan, detect, locate and measure pipeline internal defects by generating three-dimensional RGB-Depth maps using stereo camera vision combined with infrared laser profiling unit. The system does not require complex calibration procedures and it utilizes orientation correction to provide accurate real-time RGB-D maps. The defects are identified and color mapped for easier visualization. The robotic sensing system was extensively tested in laboratory conditions followed by field deployments in buried water pipes in Sydney, Australia. The experimental results show that the RGB-D maps were generated with millimeter (mm) level accuracy with demonstrated liner defect quantification.
Hasan, M, Zhao, J, Jia, F, Wu, H, Ahmad, F, Huang, Z, Wei, D, Ma, L & Jiang, Z 2021, 'Optimisation of sintering parameters for bonding nanocrystalline cemented tungsten carbide powder and solid high strength steel', Composite Interfaces, vol. 28, no. 5, pp. 477-492.
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© 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group. In this study we examined the effects of compaction pressure for bonding nanocrystalline cemented tungsten carbide (WC-10Co) and high-strength steel (AISI4340) and successfully fabricated a bilayered composite of ceramic and steel. The obtained results were compared with our previous studies, and then the optimised sintering conditions were suggested. The compaction pressure examined varied from 120–200 MPa at 1150°C for 20 min. The study shows that the change in experimental parameters has significant effects on both the sintering properties of nanocrystalline WC-10Co powders and their bonding with AISI4340 steel. The microstructure reveals a successful metallurgical bonding between ceramic and steel. Bonding temperature determines, to a great extent, the diffusion processes across the bonding interface and has found to be the most influential variable compared to sintering time and compaction pressure. The obtained average maximum bonding strength of the bimetal composite is 226 MPa, which is higher than that of previous studies.
Hossain, I, Zhou, S, Ishac, K, Lind, E, Sharwood, L & Eager, D 2021, 'A Measurement of ‘Walking-the-Wall’ Dynamics: An Observational Study Using Accelerometry and Sensors to Quantify Risk Associated with Vertical Wall Impact Attenuation in Trampoline Parks', Sensors, vol. 21, no. 21, pp. 7337-7337.
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This study illustrates the application of a tri-axial accelerometer and gyroscope sensor device on a trampolinist performing the walking-the-wall manoeuvre on a high-performance trampoline to determine the performer dynamic conditions. This research found that rigid vertical walls would allow the trampolinist to obtain greater control and retain spatial awareness at greater levels than what is achievable on non-rigid vertical walls. With a non-rigid padded wall, the reaction force from the wall can be considered a variable force that is not constrained, and would not always provide the feedback that the trampolinist needs to maintain the balance with each climb up the wall and fall from height. This research postulates that unattenuated vertical walls are safer than attenuated vertical walls for walking-the-wall manoeuvres within trampoline park facilities. This is because non-rigid walls would provide higher g-force reaction feedback from the wall, which would reduce the trampolinist’s control and stability. This was verified by measuring g-force on a horizontal rigid surface versus a non-rigid surface, where the g-force feedback was 27% higher for the non-rigid surface. Control and stability are both critical while performing the complex walking-the-wall manoeuvre. The trampolinist experienced a very high peak g-force, with a maximum g-force of approximately 11.5 g at the bottom of the jump cycle. It was concluded that applying impact attenuation padding to vertical walls used for walking-the-wall and similar activities would increase the likelihood of injury; therefore, padding of these vertical surfaces is not recommended.
Hossain, SI, Gandhi, NS, Hughes, ZE & Saha, SC 2021, 'Computational Studies of Lipid-Wrapped Gold Nanoparticle Transport Through Model Lung Surfactant Monolayers', The Journal of Physical Chemistry B, vol. 125, no. 5, pp. 1392-1401.
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Colloidal nanoparticles, such as gold nanoparticles (AuNPs), are promising materials for the delivery of hydrophilic drugs via the pulmonary route. The inhaled nanoparticle drug carriers primarily deposit in lung alveoli and interact with the alveolar surface known as lung surfactants. Therefore, it is vital to understand the interactions of nanocarriers with the surfactant layer. To understand the interactions at the molecular level, here we simulated model lung surfactant monolayers with phospholipid (PL)-wrapped AuNPs at the vacuum-water interface using coarse-grained molecular dynamics simulations. The PL-wrapped AuNPs quickly adsorbed into the surfactant layer, altered the structural properties of the monolayer, and at high concentrations initiated the compressed monolayer to collapse/buckle. Among the surfactant monolayer lipid components, cholesterol adsorbed to the AuNPs preferentially over PL species. The position of the adsorbed PL-AuNPs within the monolayer, and subsequent monolayer perturbation, vary depending on the monolayer phase, monolayer composition, and species of PL used as a ligand. Information provided by these molecular dynamic simulations helps to rationalize why some colloidal nanoparticles work better as nanocarriers than others and aid the design of new ones, to avoid biological toxicity and improve efficacy for pulmonary drug delivery.
Hossain, SI, Luo, Z, Deplazes, E & Saha, SC 2021, 'Shape matters—the interaction of gold nanoparticles with model lung surfactant monolayers', Journal of The Royal Society Interface, vol. 18, no. 183.
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The lung surfactant monolayer (LSM) forms the main biological barrier for any inhaled particles to enter our bloodstream, including gold nanoparticles (AuNPs) present as air pollutants and under investigation for use in biomedical applications. Understanding the interaction of AuNPs with lung surfactant can assist in understanding how AuNPs enter our lungs. In this study, we use coarse-grained molecular dynamics simulations to investigate the effect of four different shape D AuNPs (spherical, box, icosahedron and rod) on the structure and dynamics of a model LSM, with a particular focus on differences resulting from the shape of the AuNP. Monolayer-AuNP systems were simulated in two different states: the compressed state and the expanded state, representing inhalation and exhalation conditions, respectively. Our results indicate that the compressed state is more affected by the presence of the AuNPs than the expanded state. Our results show that in the compressed state, the AuNPs prevent the monolayer from reaching the close to zero surface tension required for normal exhalation. In the compressed state, all four nanoparticles (NPs) reduce the lipid order parameters and cause a thinning of the monolayer where the particles drag surfactant molecules into the water phase. Comparing the different properties shows no trend concerning which shape has the biggest effect on the monolayer, as shape-dependent effects vary among the different properties. Insights from this study might assist future work of how AuNP shapes affect the LSM during inhalation or exhalation conditions.
Hossain, SI, Saha, SC & Deplazes, E 2021, 'Phenolic compounds alter the ion permeability of phospholipid bilayersviaspecific lipid interactions', Physical Chemistry Chemical Physics, vol. 23, no. 39, pp. 22352-22366.
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How phenolic compounds interact with biological membranes and alter the menbrane properties.
Hosseini, SAH, Rahmani, O, Hayati, H & Jahanshir, A 2021, 'Surface effect on forced vibration of DNS by viscoelastic layer under a moving load', Coupled Systems Mechanics, vol. 10, no. 4, pp. 333-350.
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The surface effect for a forced vibration of a double-nanobeam-system (DNS) coupled by a viscoelastic layer under a moving constant load is studied in this paper. The viscoelastic layer that couples the nanobeams to each other, is modelled as spring-damper system. The Euler- Bernoulli theory and a simply supported boundary condition are considered for both nanobeams. By using the analytical solution, the dynamic displacement is obtained by considering the surface elasticity and residual tension effect on each nanobeams. Furthermore, the several significant parameters such as the velocity of the moving load, spring constant, damping coefficient and also the surface effect have been studied using some plots and examples. Finally, by observing the diagrams it was concluded that as the length of the beams reduces, the surface effect has a considerable effect on each of nanobeams especially at Nano scale, where it was not achieved by classic theories.
Huo, X, Luo, Q, Li, Q & Sun, G 2021, 'Measurement of fracture parameters based upon digital image correlation and virtual crack closure techniques', Composites Part B: Engineering, vol. 224, pp. 109157-109157.
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Husain, S, Adil, M, Arqam, M & Shabani, B 2021, 'A review on the thermal performance of natural convection in vertical annulus and its applications', Renewable and Sustainable Energy Reviews, vol. 150, pp. 111463-111463.
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Ikram, MM, Saha, G & Saha, SC 2021, 'Conjugate forced convection transient flow and heat transfer analysis in a hexagonal, partitioned, air filled cavity with dynamic modulator', International Journal of Heat and Mass Transfer, vol. 167, pp. 120786-120786.
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Ishac, K & Eager, D 2021, 'Evaluating Martial Arts Punching Kinematics Using a Vision and Inertial Sensing System', Sensors, vol. 21, no. 6, pp. 1948-1948.
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Martial arts has many benefits not only in self-defence, but also in improving physical fitness and mental well-being. In our research we focused on analyzing the velocity, impulse, momentum and impact force of the Taekwondo sine-wave punch and reverse-step punch. We evaluated these techniques in comparison with the martial arts styles of Hapkido and Shaolin Wushu and investigated the kinematic properties. We developed a sensing system which is composed of an ICSensor Model 3140 accelerometer attached to a punching bag for measuring dynamic acceleration, Kinovea motion analysis software and 2 GoPro Hero 3 cameras, one focused on the practitioner’s motion and the other focused on the punching bag’s motion. Our results verified that the motion vectors associated with a Taekwondo practitioner performing a sine-wave punch, uses a unique gravitational potential energy to optimise the impact force of the punch. We demonstrated that the sine-wave punch on average produced an impact force of 6884 N which was higher than the reverse-step punch that produced an average impact force of 5055 N. Our comparison experiment showed that the Taekwondo sine-wave punch produced the highest impact force compared to a Hapkido right cross punch and a Shaolin Wushu right cross, however the Wushu right cross had the highest force to weight ratio at 82:1. The experiments were conducted with high ranking black belt practitioners in Taekwondo, Hapkido and Shaolin Wushu.
Islam, MS, Larpruenrudee, P, Hossain, SI, Rahimi-Gorji, M, Gu, Y, Saha, SC & Paul, G 2021, 'Polydisperse Aerosol Transport and Deposition in Upper Airways of Age-Specific Lung', International Journal of Environmental Research and Public Health, vol. 18, no. 12, pp. 6239-6239.
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A comprehensive understanding of airflow characteristics and particle transport in the human lung can be useful in modelling to inform clinical diagnosis, treatment, and management, including prescription medication and risk assessment for rehabilitation. One of the difficulties in clinical treatment of lung disorders lies in the patients’ variable physical lung characteristics caused by age, amongst other factors, such as different lung sizes. A precise understanding of the comparison between different age groups with various flow rates is missing in the literature, and this study aims to analyse the airflow and aerosol transport within the age-specific lung. ANSYS Fluent solver and the large-eddy simulation (LES) model were employed for the numerical simulation. The numerical model was validated with the available literature and the computational results showed airway size-reduction significantly affected airflow and particle transport in the upper airways. This study reports higher deposition at the mouth-throat region for larger diameter particles. The overall deposition efficiency (DE) increased with airway size reduction and flow rate. Lung aging effected the pressure distribution and a higher pressure drop was reported for the aged lung as compared to the younger lung. These findings could inform medical management through individualised simulation of drug-aerosol delivery processes for the patient-specific lung.
Islam, MS, Larpruenrudee, P, Paul, AR, Paul, G, Gemci, T, Gu, Y & Saha, SC 2021, 'SARS CoV-2 aerosol: How far it can travel to the lower airways?', Physics of Fluids, vol. 33, no. 6, pp. 061903-061903.
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The recent outbreak of the SARS CoV-2 virus has had a significant effect on human respiratory health around the world. The contagious disease infected a large proportion of the world population, resulting in long-term health issues and an excessive mortality rate. The SARS CoV-2 virus can spread as small aerosols and enters the respiratory systems through the oral (nose or mouth) airway. The SARS CoV-2 particle transport to the mouth–throat and upper airways is analyzed by the available literature. Due to the tiny size, the virus can travel to the terminal airways of the respiratory system and form a severe health hazard. There is a gap in the understanding of the SARS CoV-2 particle transport to the terminal airways. The present study investigated the SARS CoV-2 virus particle transport and deposition to the terminal airways in a complex 17-generation lung model. This first-ever study demonstrates how far SARS CoV-2 particles can travel in the respiratory system. ANSYS Fluent solver was used to simulate the virus particle transport during sleep and light and heavy activity conditions. Numerical results demonstrate that a higher percentage of the virus particles are trapped at the upper airways when sleeping and in a light activity condition. More virus particles have lung contact in the right lung than the left lung. A comprehensive lobe specific deposition and deposition concentration study was performed. The results of this study provide a precise knowledge of the SARs CoV-2 particle transport to the lower branches and could help the lung health risk assessment system.
Islam, MS, Larpruenrudee, P, Saha, SC, Pourmehran, O, Paul, AR, Gemci, T, Collins, R, Paul, G & Gu, Y 2021, 'How severe acute respiratory syndrome coronavirus-2 aerosol propagates through the age-specific upper airways', Physics of Fluids, vol. 33, no. 8, pp. 081911-081911.
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The recent outbreak of the COVID-19 causes significant respirational health problems, including high mortality rates worldwide. The deadly corona virus-containing aerosol enters the atmospheric air through sneezing, exhalation, or talking, assembling with the particulate matter, and subsequently transferring to the respiratory system. This recent outbreak illustrates that the severe acute respiratory syndrome (SARS) coronavirus-2 is deadlier for aged people than for other age groups. It is evident that the airway diameter reduces with age, and an accurate understanding of SARS aerosol transport through different elderly people's airways could potentially help the overall respiratory health assessment, which is currently lacking in the literature. This first-ever study investigates SARS COVID-2 aerosol transport in age-specific airway systems. A highly asymmetric age-specific airway model and fluent solver (ANSYS 19.2) are used for the investigation. The computational fluid dynamics measurement predicts higher SARS COVID-2 aerosol concentration in the airway wall for older adults than for younger people. The numerical study reports that the smaller SARS coronavirus-2 aerosol deposition rate in the right lung is higher than that in the left lung, and the opposite scenario occurs for the larger SARS coronavirus-2 aerosol rate. The numerical results show a fluctuating trend of pressure at different generations of the age-specific model. The findings of this study would improve the knowledge of SARS coronavirus-2 aerosol transportation to the upper airways which would thus ameliorate the targeted aerosol drug delivery system.
Jahirul, MI, Rasul, MG, Brown, RJ, Senadeera, W, Hosen, MA, Haque, R, Saha, SC & Mahlia, TMI 2021, 'Investigation of correlation between chemical composition and properties of biodiesel using principal component analysis (PCA) and artificial neural network (ANN)', Renewable Energy, vol. 168, pp. 632-646.
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© 2020 Elsevier Ltd Biodiesel will provide a significant renewable energy source for transportation in the near future. In the present study, principal component analysis (PCA) has been used to understand the relationship between important properties of biodiesel and its chemical composition. Finally, several artificial intelligence-based models were developed to predict specific biodiesel properties based on their chemical composition. The experimental study was conducted in order to generate training data for the artificial neural network (ANN). Available (experimental) data from the literature was also employed for this modeling strategy. The analytical part of this study found a complex multi-dimensional correlation between chemical composition and biodiesel properties. Average numbers of double bonds in the chemical structure (representing the unsaturated component in biodiesel) and the poly-unsaturated component in biodiesel had a great impact on biodiesel properties. The simulation result in this study demonstrated that ANN is a useful tool for investigating the fuel properties from its chemical composition which eventually can replace the time consuming and costly experimental test.
Ji, JC, Luo, Q & Ye, K 2021, 'Vibration control based metamaterials and origami structures: A state-of-the-art review', Mechanical Systems and Signal Processing, vol. 161, pp. 107945-107945.
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Vibration and sound control is critical to many practical engineering systems in order to minimise the detrimental effects caused by unavoidable vibrations and noises. Metamaterials and origami-based structures, which have attracted increasing interests in interdisciplinary research fields, possess many peculiar physical properties, including negative Poisson's ratios, bi- or multi-stable states, nonlinear and tuneable stiffness features, and thus offer promising applications for vibration and sound control. This paper presents a review of metamaterials and origami-based structures as well as their applications to vibration and sound control. Metamaterials are artificially engineered materials having extremal properties which are not found in conventional materials. Metamaterials with abnormal features are firstly discussed on the basis of the unusual values of their elastic constants. Recent advances of auxetic, band gap and pentamode metamaterials are reviewed together with their applications to vibration and sound mitigations. Origami, as the ancient Japanese art of paper folding, has emerged as a new design paradigm for different applications. Origami-based structures can be adopted for vibration isolation by using their multi-stable states and desirable stiffness characteristics. Different origami patterns are reviewed to show their configurations and base structures. Special features, such as bi- or multi-stable states, dynamic Poisson's ratios, and nonlinear force–displacement relationships are discussed for their applications for vibration control. Finally, possible future research directions are elaborated for this emerging and promising interdisciplinary research field.
Jiang, C, Li, W, Deng, M & Ng, C-T 2021, 'Static component generation and measurement of nonlinear guided waves with group velocity mismatch', JASA Express Letters, vol. 1, no. 5.
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This study focuses on static component generation (SCG) and its measurement wherein a group velocity mismatch (GVM) exists between the primary guided wave and the generated static component (SC). The SCGs by primary S0, A0, and SH0 waves are investigated. It is confirmed that the SCs are S0 mode. The GVM causes the temporal waveforms of the SCs to tend to increase in width with propagation distance. A feasible method is proposed accordingly for measurement of SCG with GVM using only lead zirconic titanate based transducers, wherein the SCs generated by two counter-propagating primary waves are modulated and superposed on each other.
Jiao, Y, Wang, Y, Ding, X, Fu, B, Huang, S & Xiong, R 2021, '2-Entity Random Sample Consensus for Robust Visual Localization: Framework, Methods, and Verifications', IEEE Transactions on Industrial Electronics, vol. 68, no. 5, pp. 4519-4528.
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Krätzig, O & Sick, N 2021, 'Exploring the role of entrepreneurial passion for facilitating university technology commercialization: Insights from battery research as an interdisciplinary field', Journal of Engineering and Technology Management, vol. 60, pp. 101627-101627.
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University-industry technology commercialization (UTC) from interdisciplinary environments is promising to contribute to solutions for major socio-economic challenges. However, UTC requires considerable coordination and mediation effort and thus intrinsic motivation from the involved researchers. Thus, the objective of the present study is to explore entrepreneurial passion as a means to facilitate researchers’ intrinsic motivation for UTC activities. The interdisciplinary field of battery research is used as a representative environment for the expert interview study. Drawing on qualitative content analysis, a framework is developed, which links researchers’ intrinsic motivation to respective UTC activities, resulting in three distinct UTC-promoting roles. Implications for policy makers seeking to promote UTC, for research managers responsible for the implementation of transfer projects as well as actors from industry who have an interest in collaborative R&D with public research institutions are provided.
Li, H, Zhao, S, Pei, L, Qiao, Z, Han, D, Liu, Z, Lian, Q, Zhao, G & Wang, Z 2021, 'Thermal properties of polybenzoxazine exhibiting improved toughness: Blending with cyclodextrin and its derivatives', High Performance Polymers, vol. 33, no. 9, pp. 1012-1024.
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Polybenzoxazines are emerging as a class of high-performance thermoset polymers that can find their applications in various fields. However, its practical application is limited by its low toughness. The cyclic β-cyclodextrin and a newly synthesized derivative (β-cyclodextrin-MAH) were separately blended with benzoxazine to improve the toughness of polybenzoxazine. The results revealed that the maximum impact strength of the blend was 12.24 kJ·m−2 and 14.29 kJ·m−2 when 1 wt.% of β-Cyclodextrin and β-Cyclodextrin-MAH, respectively, were used. The strengths were 53% and 86% higher than that of pure polybenzoxazine. The curing reaction, possible chemical structures, and fractured surface were examined using differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques to understand the mechanism of generation of toughness. The results revealed that the sea-island structure and the presence of hydrogen bonds between polybenzoxazine and β-cyclodextrin and β-cyclodextrin-MAH resulted in the generation of toughness. Furthermore, the curves generated during thermogravimetric analysis did not significantly change, revealing the good thermal properties of the system. The phase-separated structure and the hydrogen bonds present in the system can be exploited to prepare synergistically tough polybenzoxazine exhibiting excellent thermal properties. This can be a potential way of modifying the thermoset resins.
Liu, L, Fryc, S, Wu, L, Vu, TL, Paul, G & Vidal-Calleja, T 2021, 'Active and Interactive Mapping With Dynamic Gaussian Process Implicit Surfaces for Mobile Manipulators', IEEE Robotics and Automation Letters, vol. 6, no. 2, pp. 3679-3686.
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In this letter, we present an interactive probabilistic mapping framework for a mobile manipulator picking objects from a pile. The aim is to map the scene, actively decide where to go next and which object to pick, make changes to the scene by picking the chosen object, and then map these changes alongside. The proposed framework uses a novel dynamic Gaussian Process (GP) Implicit Surface method to incrementally build and update the scene map that reflects environment changes. Actively the framework computes the next-best-view, balancing the terms of object reachability for picking and map information gain (IG) for fidelity and coverage. To enforce a priority of visiting boundary segments over unknown regions, the IG formulation includes an uncertainty gradient-based frontier score by exploiting the GP kernel derivative. This leads to an efficient strategy that addresses the often conflicting requirement of unknown environment exploration and object picking exploitation given a limited execution horizon. We demonstrate the effectiveness of our framework with software simulation and real-life experiments.
Liu, X, Zheng, G, Luo, Q, Li, Q & Sun, G 2021, 'Fatigue behavior of carbon fibre reinforced plastic and aluminum single-lap adhesive joints after the transverse pre-impact', International Journal of Fatigue, vol. 144, pp. 105973-105973.
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Luo, L, Jiang, Z, Wei, D & Jia, F 2021, 'A study of influence of hydraulic pressure on micro-hydromechanical deep drawing considering size effects and surface roughness', Wear, vol. 477, pp. 203803-203803.
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Luo, L, Wei, D, Zu, G & Jiang, Z 2021, 'Influence of blank holder-die gap on micro-deep drawing of SUS304 cups', International Journal of Mechanical Sciences, vol. 191, pp. 106065-106065.
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Mao, Z, Zhao, L, Huang, S, Fan, Y & Pui-Wai Lee, A 2021, 'Direct 3D ultrasound fusion for transesophageal echocardiography', Computers in Biology and Medicine, vol. 134, pp. 104502-104502.
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BACKGROUND: Real-time three-dimensional transesophageal echocardiography (3D TEE) has been increasingly used in clinic for fast 3D analysis of cardiac anatomy and function. However, 3D TEE still suffers from the limited field of view (FoV). It is challenging to adopt conventional multi-view fusion methods to 3D TEE images because feature-based registration methods tend to fail in the ultrasound scenario, and conventional intensity-based methods have poor convergence properties and require an iterative coarse-to-fine strategy. METHODS: A novel multi-view registration and fusion method is proposed to enlarge the FoV of 3D TEE images efficiently. A direct method is proposed to solve the registration problem in the Lie algebra space. Fast implementation is realized by searching voxels on three orthogonal planes between two volumes. Besides, a weighted-average 3D fusion method is proposed to fuse the aligned images seamlessly. For a sequence of 3D TEE images, they are fused incrementally. RESULTS: Qualitative and quantitative results of in-vivo experiments indicate that the proposed registration algorithm outperforms a state-of-the-art PCA-based registration method in terms of accuracy and efficiency. Image registration and fusion performed on 76 in-vivo 3D TEE volumes from nine patients show apparent enlargement of FoV (enlarged around two times) in the obtained fused images. CONCLUSIONS: The proposed methods can fuse 3D TEE images efficiently and accurately so that the whole Region of Interest (ROI) can be seen in a single frame. This research shows good potential to assist clinical diagnosis, preoperative planning, and future intraoperative guidance with 3D TEE.
Maxit, L, Karimi, M & Guasch, O 2021, 'Spatial coherence of pipe vibrations induced by an internal turbulent flow', Journal of Sound and Vibration, vol. 493, pp. 115841-115841.
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McCammon, S, Marcon dos Santos, G, Frantz, M, Welch, TP, Best, G, Shearman, RK, Nash, JD, Barth, JA, Adams, JA & Hollinger, GA 2021, 'Ocean front detection and tracking using a team of heterogeneous marine vehicles', Journal of Field Robotics, vol. 38, no. 6, pp. 854-881.
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AbstractOcean monitoring is an expensive and time consuming endeavor, but it can be made more efficient through the use of teams of autonomous robots. In this paper, we present a system for the autonomous identification and tracking of ocean fronts by coordinating the sampling efforts of a heterogeneous team of autonomous surface vehicles (ASVs) and autonomous underwater vehicles (AUVs). The primary contributions of this study are (1) our algorithm for performing autonomous coordination using general autonomy principles: Sequential Allocation Monte Carlo Tree Search (SA‐MCTS) which incorporates domain knowledge into the environmental estimation through both augmenting a standard Gaussian process with a nearest neighbors prior and planning in a drifting reference frame, (2) our decision support user interface to help human operators oversee the autonomous system, and (3) the demonstration of the system's operation in a 2‐week long deployment in the Gulf of Mexico using a heterogeneous team of four Slocum gliders and two robotic ocean surface samplers. With these contributions, we aim to bridge the gap between state of the art autonomy algorithms and marine vehicle planning methods that have been tested in large‐scale field trials. This paper presents the first deployment of a general, heuristic‐based, multi‐robot coordination algorithm for an extended sampling mission.
Mondal, RN, Hasan, MS, Islam, MS, Islam, MZ & Saha, SC 2021, 'A Computational Study on Fluid Flow and Heat Transfer Through a Rotating Curved Duct with Rectangular Cross Section', International Journal of Heat and Technology, vol. 39, no. 4, pp. 1213-1224.
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The understanding of fluid flow and heat transfer (HT) through a rotating curved duct (RCD) is important for different engineering applications. The available literature improved the understanding of the fluid flow and HT through a large-curvature rotating duct. However, the comprehensive knowledge of fluid flow and HT through an RCD with small curvature is little known. This numerical study aims to perform fluid flow characterization and HT through an RCD with curvature ratio 0.001. The spectral based numerical approach investigates the effects of rotation on fluid flow and HT for the Taylor number −1000≤Tr≤1500. A constant pressure gradient force, the Dean number Dn = 100, and a constant buoyancy force parameter, the Grashof number Gr = 500 are used for the numerical simulation. Fortran code is developed for the numerical computations and Tecplot software is used for the post-processing purpose. The numerical study investigates steady solutions and a structure of two-branches of steady solutions is obtained for positive rotation. The transient solution reports the transitional flow patterns and HT through the rotating duct, and two- to four-vortex solutions are observed. In case of negative rotation, time-dependent solutions show that the Coriolis force exhibits an opposite effect to that of the curvature so that the flow characteristics exhibit various flow instabilities. The numerical result shows that convective HT is increased with the increase of rotation and highly complex secondary flow patterns influence the overall HT from the heated wall to the fluid. To validate the numerical results, a comparison with the experimental data is provided, which shows that a good agreement is attained between the numerical and experimental investigations.
Munasinghe, N & Paul, G 2021, 'Radial slicing for helical-shaped advanced manufacturing applications', The International Journal of Advanced Manufacturing Technology, vol. 112, no. 3-4, pp. 1089-1100.
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The fourth industrial revolution (Industry 4.0) is transforming industries all around the world focusing on areas including advanced robotics and automation, sensor technology and data analytics. The authors are involved in a project developing a multi-robot material extrusion 3D printer to print a Gravity Separation Spiral (GSS), an instrument used in the mining industry to separate mineral slurry into different density components. Compared to traditional mould-based manufacturing, this new additive manufacturing method will significantly reduce manufacturing tooling costs, improve the customisation to enable the production of bespoke GSS that each process different minerals, and reduce worker exposure to hazardous materials. Slicing and printing large scale helical objects in conventional horizontal layer addition would result in an unreasonable amount of waste material from support structures, and poor surface quality due to step-wise bumps. This paper presents a novel slicing algorithm using concentric vertical ray lines to slice objects radially, enabling layers to be deposited progressively in the same fashion. This method can be applied in large scale additive manufacturing where objects are printed by a robot in a radial direction, which is different from layered vertical printing in conventional additive systems. An example GSS is sliced to generate motion plans for a print head affixed to the end effector of a robot arm. Then through simulations, it is shown how a robot's expected manipulability measure can be used to predict and ensure the successful completion of the print.
Neri, A, Cagno, E, Lepri, M & Trianni, A 2021, 'A triple bottom line balanced set of key performance indicators to measure the sustainability performance of industrial supply chains', Sustainable Production and Consumption, vol. 26, pp. 648-691.
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The measurement of sustainability within industrial supply chains is becoming increasingly relevant, with both industry and academia calling for the development of a general and manageable set of key performance indicators (KPIs). With more than 2,000 performance measures already identified by the previous literature, the real challenge lays in the development of the right set of indicators. Stemming from a thorough literature review, we propose a novel set of KPIs, based on a Balance Score Card - Supply Chain Operations Reference integrated framework. Whilst including a limited number of KPIs, the proposed set: i) assures a balanced coverage of the sustainability pillars and related intersections; ii) addresses different decision-making levels, financial bases and components of performance; iii) simultaneously tackles the sustainability performance of an entire supply chain. We empirically validated the set in 3 supply chains and 7 focal firms, by assessing its completeness, usefulness and ease of use. The set resulted suitable for different contexts of application and appropriate for the evaluation of the sustainability performance of an overall supply chain. We conclude with remarks for academia, industry and policy-makers, also sketching directions for further research.
Nguyen, L, Kodagoda, S, Ranasinghe, R & Dissanayake, G 2021, 'Mobile Robotic Sensors for Environmental Monitoring using Gaussian Markov Random Field', Robotica, vol. 39, no. 5, pp. 862-884.
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SUMMARYThis paper addresses the issue of monitoring spatial environmental phenomena of interest utilizing information collected by a network of mobile, wireless, and noisy sensors that can take discrete measurements as they navigate through the environment. It is proposed to employ Gaussian Markov random field (GMRF) represented on an irregular discrete lattice by using the stochastic partial differential equations method to model the physical spatial field. It then derives a GMRF-based approach to effectively predict the field at unmeasured locations, given available observations, in both centralized and distributed manners. Furthermore, a novel but efficient optimality criterion is then proposed to design centralized and distributed adaptive sampling strategies for the mobile robotic sensors to find the most informative sampling paths in taking future measurements. By taking advantage of conditional independence property in the GMRF, the adaptive sampling optimization problem is proven to be resolved in a deterministic time. The effectiveness of the proposed approach is compared and demonstrated using pre-published data sets with appealing results.
Ni, Q, Ji, JC, Feng, K & Halkon, B 2021, 'A novel correntropy-based band selection method for the fault diagnosis of bearings under fault-irrelevant impulsive and cyclostationary interferences', Mechanical Systems and Signal Processing, vol. 153, pp. 107498-107498.
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Demodulation analysis is one of the most effective methods for bearing fault diagnosis. However, in practical applications, the interferences from ambient noises or other rotating components may create great challenges to demodulation analysis and thus decrease its effectiveness. Generally, a selection procedure for the most informative frequency band (IFB) is usually implemented in advance to extract the fault features that are hidden by the interferences. The fast kurtogram (FK) has been utilized as a benchmark for the IFB selection. Although designed to identify the most impulsive part of the signal, the FK is inevitably affected by the fault-irrelevant impulsive and cyclostationary interferences due to the dual sensitiveness to the impulsiveness and cyclostationarity of the kurtosis, and thus it may produce a misleading band for demodulation. To address this issue, a novel and robust IFB selection method based on the fault energy of correntropy (named FECgram) is proposed in this paper to replace the FK, through which the IFB can capture the fault symptom without being influenced by the fault-irrelevant impulsive and cyclostationary interferences. The superiority of the FECgram in combination with the squared envelope spectrum (SES) is validated on both simulation data and three different challenging experimental datasets.
Oberst, S, Halkon, B, Ji, J & Brown, T 2021, 'Preface', Vibration Engineering for a Sustainable Future: Numerical and Analytical Methods to Study Dynamical Systems, Vol. 3, pp. v-vi.
Oberst, S, Halkon, B, Ji, J & Brown, T 2021, 'Preface', Vibration Engineering for a Sustainable Future: Experiments, Materials and Signal Processing, Vol. 2, vol. 2, pp. v-vi.
Oberst, S, Martin, R, Halkon, BJ, Lai, JCS, Evans, TA & Saadatfar, M 2021, 'Submillimetre mechanistic designs of termite-built structures', Journal of The Royal Society Interface, vol. 18, no. 178, pp. 1-10.
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Termites inhabit complex underground mounds of intricate stigmergic labyrinthine designs with multiple functions as nursery, food storage and refuge, while maintaining a homeostatic microclimate. Past research studied termite building activities rather than the actual material structure. Yet, prior to understanding how multi-functionality shaped termite building, a thorough grasp of submillimetre mechanistic architecture of mounds is required. Here, we identify for Nasutitermes exitiosus via granulometry and Fourier transform infrared spectroscopy analysis, preferential particle sizes related to coarse silts and unknown mixtures of organic/inorganic components. High-resolution micro-computed X-ray tomography and microindentation tests reveal wall patterns of filigree laminated layers and sub-millimetre porosity wrapped around a coarse-grained inner scaffold. The scaffold geometry, which is designed of a lignin-based composite and densely biocementitious stercoral mortar, resembles that of trabecula cancellous bones. Fractal dimension estimates indicate multi-scaled porosity, important for enhanced evaporative cooling and structural stability. The indentation moduli increase from the outer to the inner wall parts to values higher than those found in loose clays and which exceed locally the properties of anthropogenic cementitious materials. Termites engineer intricately layered biocementitious composites of high elasticity. The multiple-scales and porosity of the structure indicate a potential to pioneer bio-architected lightweight and high-strength materials.
Pan, Y, Xu, X, Ding, X, Huang, S, Wang, Y & Xiong, R 2021, 'GEM: Online Globally Consistent Dense Elevation Mapping for Unstructured Terrain', IEEE Transactions on Instrumentation and Measurement, vol. 70, no. 99, pp. 1-13.
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IEEE Online dense mapping gives a representation of the unstructured terrain, which is indispensable for safe robotic motion planning. In this paper, we propose such an elevation mapping system, namely GEM, to generate a dense local elevation map in constant real-time for fast responsive local planning, and maintain a globally consistent dense map for path routing at the same time. We model the global elevation map as a collection of submaps. When the trajectory estimation of the robot is corrected by SLAM, only relative poses between submaps are updated without re-building the submap. As a result, this deformable global dense map representation is able to keep the global consistency online. Besides, we accelerate the local mapping by integrating traversability analysis into the mapping system to save the computation cost by obstacle awareness. The system is implemented by CPU-GPU coordinated processing to guarantee constant real-time performance for in-time handling of dynamic obstacles. Substantial experimental results on both simulated and real-world dataset validate the efficiency and effectiveness of GEM.
Paul, AR, Khan, F, Jain, A & Saha, SC 2021, 'Deposition of Smoke Particles in Human Airways with Realistic Waveform', Atmosphere, vol. 12, no. 7, pp. 912-912.
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Exposure to toxic particles from smoke generated either from bush fire, stable burning, or direct smoking is very harmful to our health. The tiny particles easily penetrate deep into the lungs after exposure and damage the airways. Tobacco smoking causes the direct emission of 2.6 million tons of CO2 and 5.2 million tons of methane annually into the atmosphere. Nevertheless, it is one of the significant contributors to various respiratory diseases leading to lung cancer. These particles’ deposition in the human airway is computed in the present article for refining our understanding of the adverse health effects due to smoke particle inhalation, especially cigarette smoke. Until recently, little work has been reported to account for the transient flow pattern of cigarette smoking. Consideration of transient flow may change the deposition pattern of the particle. A high-resolution CT scan image of the respiratory tract model consisting of the oral cavity, throat, trachea, and first to sixth generations of the lungs helps predict cigarette smoke particle (CSP) deposition. With the same scan, a realistic geometric model of the human airways of an adult subject is used to simulate the transport of air and particle. The CSP deposition is determined at different locations from the oral cavity to the sixth generation of the bronchi. In addition, an unsteady breathing curve indicative of realistic smoking behavior is utilized to represent the breathing conditions accurately. The discrete phase model (DPM) technique is used to determine smoke particle deposition in the human airways. It is found that the deposition increases with the size of the smoke particle. Particles tend to deposit in the oral cavity around the bifurcation junction of the airways. The deposition fraction of CSP with the realistic waveform of smoking is found to be smaller compared to that during the stable flow condition. It is also observed that the fine particles (0.1–1.0 micron) ...
Pei, L, Zhao, S, Li, H, Zhang, X, Fan, X, Wang, W, Zhang, C, Zhao, G & Wang, Z 2021, 'Preparation of low temperature cure polybenzoxazine coating with enhanced thermal stability and mechanical properties by combustion synthesis approach', Polymer, vol. 220, pp. 123573-123573.
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Peng, J, Parnell, J & Kessissoglou, N 2021, 'Spatially differentiated profiles for road traffic noise pollution across a state road network', Applied Acoustics, vol. 172, pp. 107641-107641.
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Priam, SS, Ikram, MM, Saha, S & Saha, SC 2021, 'Conjugate natural convection in a vertically divided square enclosure by a corrugated solid partition into air and water regions', Thermal Science and Engineering Progress, vol. 25, pp. 101036-101036.
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Quin, P, Nguyen, DDK, Vu, TL, Alempijevic, A & Paul, G 2021, 'Approaches for Efficiently Detecting Frontier Cells in Robotics Exploration.', Frontiers Robotics AI, vol. 8, pp. 616470-616470.
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Many robot exploration algorithms that are used to explore office, home, or outdoor environments, rely on the concept of frontier cells. Frontier cells define the border between known and unknown space. Frontier-based exploration is the process of repeatedly detecting frontiers and moving towards them, until there are no more frontiers and therefore no more unknown regions. The faster frontier cells can be detected, the more efficient exploration becomes. This paper proposes several algorithms for detecting frontiers. The first is called Naïve Active Area (NaïveAA) frontier detection and achieves frontier detection in constant time by only evaluating the cells in the active area defined by scans taken. The second algorithm is called Expanding-Wavefront Frontier Detection (EWFD) and uses frontiers from the previous timestep as a starting point for searching for frontiers in newly discovered space. The third approach is called Frontier-Tracing Frontier Detection (FTFD) and also uses the frontiers from the previous timestep as well as the endpoints of the scan, to determine the frontiers at the current timestep. Algorithms are compared to state-of-the-art algorithms such as Naïve, WFD, and WFD-INC. NaïveAA is shown to operate in constant time and therefore is suitable as a basic benchmark for frontier detection algorithms. EWFD and FTFD are found to be significantly faster than other algorithms.
Rahman, MM, Zhao, M, Islam, MS, Dong, K & Saha, SC 2021, 'Aging effects on airflow distribution and micron-particle transport and deposition in a human lung using CFD-DPM approach', Advanced Powder Technology, vol. 32, no. 10, pp. 3506-3516.
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Rahman, MM, Zhao, M, Islam, MS, Dong, K & Saha, SC 2021, 'Numerical study of nanoscale and microscale particle transport in realistic lung models with and without stenosis', International Journal of Multiphase Flow, vol. 145, pp. 103842-103842.
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Richmond, JL & Halkon, BJ 2021, 'Speaker Diarisation of Vibroacoustic Intelligence from Drone Mounted Laser Doppler Vibrometers', Journal of Physics: Conference Series, vol. 2041, no. 1, pp. 012011-012011.
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Roche, CD, Zhou, Y, Zhao, L & Gentile, C 2021, 'A World-First Surgical Instrument for Minimally Invasive Robotically-Enabled Transplantation of Heart Patches for Myocardial Regeneration: A Brief Research Report', Frontiers in Surgery, vol. 8, p. 653328.
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Graphical Abstract
Romeijn, T, Singh, K, Behrens, M & Paul, G 2021, 'Effect of accelerated weathering on the creep behaviour of additively manufactured Polyethylene Terephthalate Glycol (PETG)', Journal of Polymer Research, vol. 28, no. 9, p. 352.
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As additively manufactured components move away from short-term usability, such as single-use prototypes, towards commercial products used for longer periods of time, the long-term material properties, such as ageing and creep, are becoming increasingly important design considerations. Moreover, when additively manufactured components are designed for outdoor use, environmental stressors affect these long-term material properties in a process known as ‘weathering’. In this research paper, an initial set of experiments assessed the flexural creep behaviour of pellet-printed PETG after exposure to three accelerated environmental stressors: UV radiation, temperature and humidity. The outcomes thereof indicated that UV exposure was the only stressor to increase the creep compliance. A subsequent set of experiments increase the UV exposure duration from 100 to 200 h and excluded the effects of ageing on creep behaviour during creep tests. The outcome of this second series of experiments showed that the increase in creep compliance can be attributed to the effects of UV alone.
Ruppert, MG, Fleming, AJ & Yong, YK 2021, 'Active atomic force microscope cantilevers with integrated device layer piezoresistive sensors', Sensors and Actuators A: Physical, vol. 319, pp. 112519-112519.
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Saroya, M, Best, G & Hollinger, GA 2021, 'Roadmap Learning for Probabilistic Occupancy Maps With Topology-Informed Growing Neural Gas', IEEE Robotics and Automation Letters, vol. 6, no. 3, pp. 4805-4812.
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We address the problem of generating navigation roadmaps for uncertain and cluttered environments represented with probabilistic occupancy maps. A key challenge is to generate roadmaps that provide connectivity through tight passages and paths around uncertain obstacles. We propose the topology-informed growing neural gas algorithm that leverages estimates of probabilistic topological structures computed using persistent homology theory. These topological structure estimates inform the random sampling distribution to focus the roadmap learning on challenging regions of the environment that have not yet been learned correctly. We present experiments for three real-world indoor point-cloud datasets represented as Hilbert maps. Our method outperforms baseline methods in terms of graph connectivity, path solution quality, and search efficiency. Compared to a much denser PRM*, our method achieves similar performance while enabling a 27× faster query time for shortest-path searches.
Seethaler, R, Mansour, SZ, Ruppert, MG & Fleming, AJ 2021, 'Position and force sensing using strain gauges integrated into piezoelectric bender electrodes', Sensors and Actuators A: Physical, vol. 321, pp. 112416-112416.
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Sepehrirahnama, S, Oberst, S, Chiang, YK & Powell, D 2021, 'Acoustic radiation force and radiation torque beyond particles: Effects of nonspherical shape and Willis coupling', Physical Review E, vol. 104, no. 6, pp. 1-11.
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Acoustophoresis mainly deals with the manipulation of subwavelength scatterers in an incident acoustic field. The geometric details of manipulated particles are often neglected by replacing them with equivalent symmetric geometries such as spheres, spheroids, cylinders, or disks. It has been demonstrated that geometric asymmetry, represented by Willis coupling terms, can strongly affect the scattering of a small object; hence neglecting these terms may miss important force contributions. In this work, we present a generalized formalism of acoustic radiation force and radiation torque based on the polarizability tensor, where Willis coupling terms are included to account for geometric asymmetry. Following Gorkov's approach, the effects of geometric asymmetry are explicitly formulated as additional terms in the radiation force and torque expressions. By breaking the symmetry of a sphere along one axis using intrusion and protrusion, we characterize the changes in the force and torque in terms of partial components, associated with the direct and Willis coupling coefficients of the polarizability tensor. We investigate the cases of standing and traveling plane waves and show how the equilibrium positions and angles are shifted by these additional terms. We show that while the contributions of asymmetry to the force are often negligible for small particles, these terms greatly affect the radiation torque. Our presented theory, providing a way of calculating radiation force and torque directly from polarizability coefficients, shows that it is essential to account for shape of objects undergoing acoustophoretic manipulation, with important implications for applications such as the manipulation of biological cells.
Shams, M, Rafiq, N, Kausar, N, Ahmed, SF, Mir, NA & Chandra Saha, S 2021, 'Inverse Family of Numerical Methods for Approximating All Simple and Roots with Multiplicity of Nonlinear Polynomial Equations with Engineering Applications', Mathematical Problems in Engineering, vol. 2021, pp. 1-9.
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A new inverse family of the iterative method is interrogated in the present article for simultaneously estimating all distinct and multiple roots of nonlinear polynomial equations. Convergence analysis proves that the order of convergence of the newly constructed family of methods is two. The computer algebra systems CAS-Mathematica is used to determine the lower bound of convergence order, which justifies the local convergence of the newly developed method. Some nonlinear models from physics, chemistry, and engineering sciences are considered to demonstrate the performance and efficiency of the newly constructed family of inverse simultaneous methods in comparison to classical methods in the literature. The computational time in seconds and residual error graph of the inverse simultaneous methods are also presented to elaborate their convergence behavior.
Stender, M, Tiedemann, M, Spieler, D, Schoepflin, D, Hoffmann, N & Oberst, S 2021, 'Deep learning for brake squeal: Brake noise detection, characterization and prediction', Mechanical Systems and Signal Processing, vol. 149, pp. 107181-107181.
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Despite significant advances in modeling of friction-induced vibrations and brake squeal, the majority of industrial research and design is still conducted experimentally, since many aspects of squeal and its mechanisms involved remain unknown. In practice, measurement data is available in large amounts. We report here for the first time on novel strategies for handling data-intensive vibration testings to gain better insights into friction brake system vibrations and noise generation mechanisms. Machine learning-based methods to detect and characterize vibrations, to understand sensitivities and to predict brake squeal are applied with the aim to illustrate how interdisciplinary approaches can leverage the potential of data science techniques for classical mechanical engineering challenges.
In the first part, a deep learning brake squeal detector is developed to identify several classes of typical friction noise recordings. The detection method is rooted in recent computer vision techniques for object detection based on convolutional neural networks (CNN). It allows to overcome limitations of classical approaches that solely rely on instantaneous spectral properties of the recorded noise. Results indicate superior detection and characterization quality when compared to a state-of-the-art brake squeal detector. In the second part, a recurrent neural network (RNN) is employed to learn the parametric patterns that determine the dynamic stability of an operating brake system. Given a set of multivariate loading conditions, the RNN learns to predict the noise generation of the structure. The validated RNN represents a virtual twin model for the squeal behavior of a specific brake system. It is found that this model can predict the occurrence and the onset of brake squeal with high accuracy and that it can identify the complicated patterns and temporal dependencies in the loading conditions that drive the dynamical structure into regimes of instability. Large data se...
Sun, G, Kong, X, Wang, Z, Luo, Q & Li, Q 2021, 'Experimental investigation into stamping of woven CF/PP laminates: Influences of molding temperature on thermal, mesoscopic and macroscopic properties', Composite Structures, vol. 263, pp. 113507-113507.
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Sun, G, Li, W, Luo, Q & Li, Q 2021, 'Modal identification of vibrating structures using singular value decomposition and nonlinear iteration based on high-speed digital image correlation', Thin-Walled Structures, vol. 163, pp. 107377-107377.
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This study aims to develop an effective method to identifying modal parameters of vibrating structures using digital image correlation (DIC) technique, in which singular value decomposition (SVD) and nonlinear least square iteration are integrated. The proposed approach was first used to measure modal parameters of a cantilever plate to verify its effectiveness and accuracy. The obtained results were compared with those measured with the forced normal mode test, operating deflection shape measurement, accelerometer, Laser Doppler Vibrometer and finite element techniques. In the experiment, synchronization of the hammer hitting and high-speed camera signals was achieved via the data acquisition cards and Labview program. Natural frequency and damping ratios were obtained through the enhanced frequency response functions with a nonlinear least square algorithm; and the mode shapes were determined through singular value decomposition. The experimental modal parameters of the cantilever plate identified by the present method agreed well with those identified by the Polymax modal estimator in the commercial code LMS test.lab and rational fraction polynomial. It is demonstrated that use of DIC technique for vibration analysis is of considerable advantages in comparison with the accelerometer and LDV techniques. Finally, a real-life case study was performed for vibratory modal analysis of a passenger car bonnet in this study. It is shown that the experimental modal parameters of the real car bonnet identified by the present method agreed well with those identified by the forced normal mode and the accelerometer tests. The proposed technique is anticipated to provide an effective approach for identification of modal parameters of vibrating structures in practical applications.
Sun, G, Xia, X, Liu, X, Luo, Q & Li, Q 2021, 'On quasi-static behaviors of different joint methods for connecting carbon fiber reinforce plastic (CFRP) laminate and aluminum alloy', Thin-Walled Structures, vol. 164, pp. 107657-107657.
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This paper reports an experimental investigation into mechanical behaviors and failure mechanisms of different joint methods for dissimilar materials, including adhesive joints, rivet joints, and hybrid joints with adhesive and rivet. In this study, a series of quasi-static tensile tests were conducted for different joint methods. The digital image correlation (DIC) technique was used to scrutinize the deformation and failure process in situ in real time. The failure modes were identified through macro-/microscopic analyses. The effects of rivet directions and filling enhancement on the joint behavior were characterized by means of experimental and theoretical methods. The results indicated that the hybrid connection exhibited the best mechanical characteristics among these three types of joints. Importantly, an interactive enhancement effect between the rivet and adhesive was identified in the hybrid joints. It was further found that the filling adhesive in a preformed hole of the substrate could better disperse the stress around it and effectively reduce the stress concentration near the hole edge. This paper provides some new insights into the design of different joint methods for dissimilar materials through a comparative study, which exhibits considerable potential and credibility for applying hybrid joints in engineering practice.
Sun, G, Zuo, W, Chen, D, Luo, Q, Pang, T & Li, Q 2021, 'On the effects of temperature on tensile behavior of carbon fiber reinforced epoxy laminates', Thin-Walled Structures, vol. 164, pp. 107769-107769.
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As a highly promising lightweight material, carbon fiber reinforced plastics (CFRP) composites have been widely used in aerospace, marine and automotive industries, which could expose to low or high thermal environments with varying material properties. This study investigated the effects of temperature variation ranging from −30 °C to 160 °C on tensile properties of CFRP experimentally and theoretically. The specimens were prepared using thermo-forming technology; and the glass transition temperatures of epoxy resins were measured by dynamic mechanical analysis (DMA). Digital image correlation (DIC) technique was used to capture the variation in strain and damage fields. By means of scanning electron microscopy (SEM), the failure mechanisms, delamination and resin softening, were identified by scrutinizing the images of fracture areas subject to different temperatures. The two-parameter Weibull analysis was conducted to evaluate the theoretical tensile strengths from relatively discrete data. The obtained Weibull parameters are considered useful for the reliability analysis of CFRP structures. It is found that the tensile strength decreases with the increase of temperature in a nonlinear fashion, which can be modeled in terms of a tanh function by correlating with the temperature-dependent experimental data. The study is anticipated to provide fundamental understanding and a predictive tool for mechanical strength of composite structures operating under different thermal conditions.
Tiwari, A, Jain, A, Paul, AR & Saha, SC 2021, 'Computational evaluation of drug delivery in human respiratory tract under realistic inhalation', Physics of Fluids, vol. 33, no. 8, pp. 083311-083311.
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In recent years, pulmonary diseases have posed severe health problems because of increasing air pollution. Some of the promising drug delivery devices for administering the active pharmaceutical ingredients through the pulmonary route include a pressurized metered-dose inhaler and dry powder inhaler (DPI) for the management of respiratory illness. The drug settling (deposition) efficiency in different regions of a human respiratory tract (HRT) for different drug particle sizes is computed using the discrete phase model in the current study. A computer tomography-based realistic HRT replica is used for this purpose with different inhalation rates following a realistic inhalation profile through the DPI device. Unsteady flow analysis is carried out in a human respiratory system up to the sixth-generation bronchi. The particle force balance equation is used in the discrete-phase model to simulate the motion of drug particles in the HRT. Low, moderate, and high inhalation rates following realistic inhalation profiles are used in the present study. The particles of larger size are deposited more in the oral cavity and are deposited higher at a higher inhalation rate due to higher inertia force. It is also observed that drug particle size plays a key role in drug delivery through dry powder inhalers. It is also found that drugs should contain smaller-sized particles (called fine particles) to enable their reach in the distal bronchi.
Trianni, A, Cagno, E, Dolšak, J & Hrovatin, N 2021, 'Implementing energy efficiency measures: do other production resources matter? A broad study in Slovenian manufacturing small and medium-sized enterprises', Journal of Cleaner Production, vol. 287, pp. 125044-125044.
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© 2020 Elsevier Ltd Literature has largely investigated barriers to energy efficiency in industrial firms. Recently, research is looking at the non-energy benefits accompanying the adoption of energy efficiency measures that may contribute to overcoming these barriers. In our study we take an innovative perspective by specifically exploring the relationships between energy efficiency measures and other production resources, being assessed by their importance and capability of firms to manage them efficiently. By analysing 10% of Slovenian small and medium-sized manufacturing firms, our exploratory findings show that decision-makers carefully look at the multiple effects (either positive or negative) energy efficiency measures may have on a number of other production resources, particularly on those closer to the production (shop floor). Additionally, companies seem to struggle in efficiently managing the most important production resources, thus suggesting that energy efficiency measures should be looked in close consideration to other resources, which represents a new barrier to energy efficiency not accounted by previous research. Further, we could not detect significant differences between clusters of small versus medium-sized firms and energy intensive versus non-energy intensive ones, differently from previous research that was emphasizing the larger perception of barriers in smaller and less energy intensive firms. Our findings may challenge the discussion over incentive schemes for energy efficiency measures by promoting those with the largest (positive) implications for other production resources.
Ulapane, N, Thiyagarajan, K, Miro, JV & Kodagoda, S 2021, 'Surface Representation of Pulsed Eddy Current Sensor Signals for Improved Ferromagnetic Material Thickness Quantification', IEEE Sensors Journal, vol. 21, no. 4, pp. 5413-5422.
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Wang, X, Bhowmick, S, Tian, ZF, Saha, SC & Xu, F 2021, 'Experimental study of natural convection in a V-shape-section cavity', Physics of Fluids, vol. 33, no. 1, pp. 014104-014104.
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Natural convection in a V-shaped section cavity heated from below and cooled from above is investigated experimentally for the first time in the literature. Temperature measurements using fast-response thermistors and flow visualization using the shadowgraph technology have been performed. The natural convection development in the cavity including the conductional, the transitional, and the fully developed stages is described. It is experimentally proven that the scaling law of the thermal boundary layer thickness is δT ∼ (κt)1/2 and the scaling law of the plume velocity is vp ∼ κRa7/15/l. Furthermore, the occurrence of Hopf bifurcation in the transition to chaos and the flow structure are also identified experimentally. The power spectral density of the temperature time series reveals that the dominant frequency of the oscillations of the unsteady flow depends on the Rayleigh number, which is quantified.
Wang, Z, Xie, H, Luo, Q, Li, Q & Sun, G 2021, 'Optimizaition for formability of plain woven carbon fiber fabrics', International Journal of Mechanical Sciences, vol. 197, pp. 106318-106318.
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How to take full advantages of the strong designability of plain woven carbon fiber fabric is a key problem urgently needed to be solved in the application of plain woven carbon fiber fabric reinforced thermoplastics (PW-CFRTPs). This study explored formability of plain woven carbon fiber fabric experimentally and numerically through stamping process, and attempted to develop efficient multiobjective optimization for further improving formability of plain woven carbon fiber fabric. First, the mechanical properties and formability of the carbon fiber fabric were characterized using the experimental tests, and then the finite element (FE) analysis involving the hypoelastic constitutive model was carried out to capture non-orthogonal behaviors of the fabric. Second, influences of blank holding force as well as blank holding area (BHA) on the formability of the fabric were investigated, and the forming characteristics including shear angle distribution, wrinkling strain and draw-in features were analyzed using the validated finite element model. Finally, a global multiobjective optimization algorithm based upon the Kriging Believer strategy was employed to optimize the formability of the fabric. The results indicated that the wrinkling strain along fiber increased with increasing shear angle; and the formability of carbon fiber fabric was largely improved through the optimization in comparison with the baseline design.
Wilkinson, S, Carmichael, M & Khonasty, R 2021, 'Towards smart green wall maintenance and Wallbot technology', Property Management, vol. 39, no. 4, pp. 466-478.
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PurposeThe UN forecast of a 3-degree Celsius global temperature increase by 2,100 will exacerbate excessive heat. Population growth, urban densification, climate change and global warming contribute to heat waves, which are more intense in high-density environments. With urbanisation, vegetation is replaced by impervious materials which contribute to the urban heat island effect. Concurrently, adverse health outcomes and heat- related deaths are increasing, and heat stress affects labour productivity. More green infrastructure, such as green walls, is needed to mitigate these effects; however maintenance costs, OH&S issues and perceptions of fire risk inhibit take up. What if these barriers could be overcome by a green Wallbot? This research examines the feasibility of integrating smart technology in the form of a Wallbot.Design/methodology/approachThe research design comprised two workshops with key stakeholders; comprising green wall designers and installers, green wall maintenance teams, project managers and building owners with green wall installations, horticulture scientists, designers and mechatronics engineers. The aim was to gain a deeper understanding of the issues affecting maintenance of green walls on different building types in New South Wales Australia to inform the design of a prototype robot to maintain green walls.FindingsThe Wallbot has great potential to overcome the perceived barriers associated with maintaining green walls and also fire risk and detection. If these barriers are addressed, other locations, such as the sides of motorways or rail corridors, could be used for more green wall installations thereby increasing mitigation of UHI. This innovation woul...
Woolfrey, J, Lu, W & Liu, D 2021, 'Predictive End-Effector Control of Manipulators on Moving Platforms Under Disturbance', IEEE Transactions on Robotics, vol. 37, no. 6, pp. 2210-2217.
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This article proposes a predictive end-effector control method for manipulators operating on mobile platforms subjected to unwanted base motion. Time series is used to forecast the base motion using historical state information. Then, a trajectory specified in the inertial frame is transformed to a predicted trajectory with respect to the manipulator. By tracking this transformed trajectory, the manipulator negates the base motion. A model-predictive control problem is formulated via quadratic programming (QP) to track said trajectory over the prediction horizon. Only the first control action in the control sequence is constrained by kinematic feasibility. In this manner, QP can be swiftly solved with linear inequality constraints. It is shown that the actual joint trajectory executed by the manipulator is always kinematically feasible. Moreover, tracking error can still be reduced despite future predicted control actions being infeasible. The method is validated through both simulation and experiment. The proposed method can reduce pose error by over 60% compared to a proportional-integral feedback controller.
Wu, L, Lee, KMB, Liu, L & Vidal-Calleja, T 2021, 'Faithful Euclidean Distance Field From Log-Gaussian Process Implicit Surfaces', IEEE Robotics and Automation Letters, vol. 6, no. 2, pp. 2461-2468.
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Xiao, T, Zhao, S, Qiu, X & Halkon, B 2021, 'Using a Retro-Reflective Membrane and Laser Doppler Vibrometer for Real-Time Remote Acoustic Sensing and Control', Sensors, vol. 21, no. 11, pp. 3866-3866.
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Microphones have been extensively studied for many decades and their related theories are well-established. However, the physical presence of the sensor itself limits its practicality in many sound field control applications. Laser Doppler vibrometers (LDVs) are commonly used for the remote measurement of surface vibration that are related to the sound field without the introduction of any such physical intervention. This paper investigates the performance and challenges of using a piece of retro-reflective film directly as an acoustic membrane pick-up with an LDV to sense its vibration to form a remote acoustic sensing apparatus. Due to the special properties of the retro-reflective material, the LDV beam can be projected to the target over a wide range of incident angles. Thus, the location of the LDV relative to the pick-up is not severely restricted. This is favourable in many acoustic sensing and control applications. Theoretical analysis and systematic experiments were conducted on the membrane to characterise its performance. One design has been selected for sensing sound pressure level above 20 dB and within the 200 Hz to 4 kHz frequency range. Two example applications—remote speech signal sensing/recording and an active noise control headrest—are presented to demonstrate the benefits of such a remote acoustic sensing apparatus with the retro-reflective material. Particularly, a significant 22.4 dB noise reduction ranging from 300 Hz to 6 kHz has been achieved using the demonstrated active control system. These results demonstrate the potential for such a solution with several key advantages in many applications over traditional microphones, primarily due to its minimal invasiveness.
Xue, H, Saha, SC, Beier, S, Jepson, N & Luo, Z 2021, 'Topological Optimization of Auxetic Coronary Stents Considering Hemodynamics', Frontiers in Bioengineering and Biotechnology, vol. 9.
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This paper is to design a new type of auxetic metamaterial-inspired structural architectures to innovate coronary stents under hemodynamics via a topological optimization method. The new architectures will low the occurrence of stent thrombosis (ST) and in-stent restenosis (ISR) associated with the mechanical factors and the adverse hemodynamics. A multiscale level-set approach with the numerical homogenization method and computational fluid dynamics is applied to implement auxetic microarchitectures and stenting structure. A homogenized effective modified fluid permeability (MFP) is proposed to efficiently connect design variables with motions of blood flow around the stent, and a Darcy-Stokes system is used to describe the coupling behavior of the stent structure and fluid. The optimization is formulated to include three objectives from different scales: MFP and auxetic property in the microscale and stenting stiffness in the macroscale. The design is numerically validated in the commercial software MATLAB and ANSYS, respectively. The simulation results show that the new design can not only supply desired auxetic behavior to benefit the deliverability and reduce incidence of the mechanical failure but also improve wall shear stress distribution to low the induced adverse hemodynamic changes. Hence, the proposed stenting architectures can help improve safety in stent implantation, to facilitate design of new generation of stents.
Yang, Y, Ma, B, Liu, X, Zhao, L & Huang, S 2021, 'GSAP: A Global Structure Attention Pooling Method for Graph-Based Visual Place Recognition', Remote Sensing, vol. 13, no. 8, pp. 1467-1467.
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The Visual Place Recognition problem aims to use an image to recognize the location that has been visited before. In most of the scenes revisited, the appearance and view are drastically different. Most previous works focus on the 2-D image-based deep learning method. However, the convolutional features are not robust enough to the challenging scenes mentioned above. In this paper, in order to take advantage of the information that helps the Visual Place Recognition task in these challenging scenes, we propose a new graph construction approach to extract the useful information from an RGB image and a depth image and fuse them in graph data. Then, we deal with the Visual Place Recognition problem as a graph classification problem. We propose a new Global Pooling method—Global Structure Attention Pooling (GSAP), which improves the classification accuracy by improving the expression ability of the Global Pooling component. The experiments show that our GSAP method improves the accuracy of graph classification by approximately 2–5%, the graph construction method improves the accuracy of graph classification by approximately 4–6%, and that the whole Visual Place Recognition model is robust to appearance change and view change.
Ye, K, Ji, JC & Brown, T 2021, 'A novel integrated quasi-zero stiffness vibration isolator for coupled translational and rotational vibrations', Mechanical Systems and Signal Processing, vol. 149, pp. 107340-107340.
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Yin, H, Wang, Y, Tang, L, Ding, X, Huang, S & Xiong, R 2021, '3D LiDAR Map Compression for Efficient Localization on Resource Constrained Vehicles', IEEE Transactions on Intelligent Transportation Systems, vol. 22, no. 2, pp. 837-852.
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Yu, J, Nerse, C, Chang, K-J & Wang, S 2021, 'A framework of flexible locally resonant metamaterials for attachment to curved structures', International Journal of Mechanical Sciences, vol. 204, pp. 106533-106533.
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Zhang, S, Zhao, L, Huang, S, Ye, M & Hao, Q 2021, 'A Template-Based 3D Reconstruction of Colon Structures and Textures From Stereo Colonoscopic Images', IEEE Transactions on Medical Robotics and Bionics, vol. 3, no. 1, pp. 85-95.
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This article presents a framework for 3D reconstruction of colonic surface using stereo colonoscopic images. Due to the limited overlaps between consecutive frames and the nonexistence of large loop closures during a normal screening colonoscopy, the state-of-art simultaneous localization and mapping (SLAM) algorithms cannot be directly applied to this scenario, thus a colon model segmented from CT scans is used together with the colonosocopic images to achieve the colon 3D reconstruction with high accuracy. The proposed framework includes 3D scan (point cloud with RGB information) reconstruction from stereo images, a visual odometry (VO) based camera pose initialization module, a 3D registration scheme for matching texture scans to the segmented colon model, and a barycentric-based texture rendering module for mapping textures from colonoscopic images to the reconstructed colonic surface. A realistic simulator is developed using Unity to simulate the procedures of colonoscopy and used to provide experimental datasets in different scenarios. Experimental results demonstrate the good performance of the proposed 3D colonic surface reconstruction method in terms of accuracy and robustness. Currently, the framework requires a pre-operative colon model as the template for colon reconstruction and can reconstruct 3D colon maps when the colon has no large deformation and the colon structure is clearly visible. The datasets used in this article and the developed simulator are made publicly available for other researchers to use (https://github.com/zsustc/colon_reconstruction_dataset).
Zhang, X, Ye, H, Wei, N, Tao, R & Luo, Z 2021, 'Design optimization of multifunctional metamaterials with tunable thermal expansion and phononic bandgap', Materials & Design, vol. 209, pp. 109990-109990.
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Zhao, F, Ji, J, Luo, Q, Cao, S, Chen, L & Du, W 2021, 'An improved quasi-zero stiffness isolator with two pairs of oblique springs to increase isolation frequency band', Nonlinear Dynamics, vol. 104, no. 1, pp. 349-365.
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Quasi-zero stiffness (QZS) isolators can achieve superior performance in vibration isolation; however, this superiority is often effective only for an excitation with the small excitation amplitude due to the narrow QZS region around the static equilibrium positions. A QZS isolator with multi-pairs of oblique springs can increase the QZS region, but its isolation frequency band is still narrow owing to the large static deflection. This article presents an improved isolator with two pairs of oblique springs by setting an initial position to be located between the supporting points of the upper pair of oblique springs and the equilibrium position so that the static deflection is significantly decreased, and thus, the isolation frequency band can be considerably increased. New formulations of stiffness and displacement transmissibility are derived for the improved QZS isolator. A prototype is designed, fabricated and tested to verify benefits of the present QZS isolator for vibration mitigation. Numerical results of the present isolator predicted by experiment and theory are compared with those of the corresponding linear isolator and previous QZS isolator to show advantages of the innovated design for vibration isolation.
Zhao, F, Ji, J, Ye, K & Luo, Q 2021, 'An innovative quasi-zero stiffness isolator with three pairs of oblique springs', International Journal of Mechanical Sciences, vol. 192, pp. 106093-106093.
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© 2020 Elsevier Ltd This paper presents an innovative design of the quasi-zero stiffness (QZS) isolator with three pairs of oblique springs. Formulations of stiffness are firstly derived and parameter study is then conducted to obtain an optimal design of the proposed isolator. The proposed isolator initially has five independent parameters. By imposing stiffness and its second order derivative to be zero at the static equilibrium position, there exist three independent parameters that can be optimised to design this type of QZS isolator. A distinctive feature of the proposed isolator is that there exists a nearly horizontal straight line near the equilibrium position in the stiffness curve as the nonlinear coefficient of the Taylor expansion up to the third order of the elastic force or the Duffing differential equation is very small; thus a wider QZS region with lower transmissibility can be achieved in the present isolator. Static and dynamic analyses are presented with focusing on dynamic response in terms of displacement transmissibility. A prototype is fabricated and tested to evaluate the proposed design. The experimental results validate the present formulations in static and dynamic analyses and show lower transmissibility as compared to the corresponding QZS isolator with one pair of oblique springs and the linear isolator.
Zhao, J, Li, T, Yang, T, Zhao, L & Huang, S 2021, '2D Laser SLAM With Closed Shape Features: Fourier Series Parameterization and Submap Joining', IEEE Robotics and Automation Letters, vol. 6, no. 2, pp. 1527-1534.
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One of the valuable directions in feature based SLAM is to parameterize and estimate features accurately. In the real world, closed shape features are especially common. It is necessary to study the feature based SLAM problem on closed shape features. The main contribution of this letter is a 2D laser SLAM approach with Fourier series based feature parameterization and submap joining. In this letter, the Fourier series are introduced to parameterize irregular closed shape features and the SLAM problem with Fourier series feature parameterization is formulated. A submap joining process is also derived in order to reduce the high dependence on precise initial guess and the computing time. The proposed method has been evaluated on both synthetic and actual data and is able to obtain accurate trajectory and feature boundaries. The practical experiment also shows that our method surpasses Cartographer under certain scenarios. We also show that our method has the ability to be applied to the general environment.
Zhao, S, Pei, L, He, J, Zhang, X, Hu, W, Yan, H, Zhao, G, Zhang, C & Wang, Z 2021, 'Curing mechanism, thermal and ablative properties of hexa-(4-amino-phenoxy) cyclotriphosphazene/benzoxazine blends', Composites Part B: Engineering, vol. 216, pp. 108838-108838.
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Zhao, S, Qiu, X, Burnett, I, Rigby, M & Lele, A 2021, 'A lumped-parameter model for sound generation in gas metal arc welding', Mechanical Systems and Signal Processing, vol. 147, pp. 107085-107085.
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It is found that the welding sound generated in Gas Metal Arc Welding (GMAW) can help human welders to improve welding quality; however, little work has been reported on the sound generation and prediction in GMAW processes. To investigate the sound generation in GMAW, this paper proposes a lumped-parameter model to predict the sound signals at the short-circuiting mode in GMAW, where the power source is modeled by a simple resistor–inductor electrical circuit and the metal droplet dynamics is modeled by a mass-spring model. The simulation results of the welding current, arc voltage, and sound signals are found to be in a reasonable agreement with the experimental measurements. Both simulation and experiment results show that the welding current increases from a base value in the arcing phase to a peak value in the short-circuiting phase first and then slumps to the base value; the voltage is close to zero in the short-circuiting phase corresponding to the current peaks and fluctuates in the arcing phase due to the uncertainties in the arc resistance; and an acoustic impulse is formed at each peak current and valley voltage in the short-circuiting phase, indicating that the sound generation is related to the energy release during the arc re-ignition process. The proposed lumped-parameter model can be used to investigate the effect of the input welding parameters on the welding sound.
Zheng, G, He, Z, Wang, K, Liu, X, Luo, Q, Li, Q & Sun, G 2021, 'On failure mechanisms in CFRP/Al adhesive joints after hygrothermal aging degradation following by mechanical tests', Thin-Walled Structures, vol. 158, pp. 107184-107184.
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Zheng, Y, Wang, Y, Luo, Z, Lu, X & Qu, J 2021, 'Concurrent design for structures and material microstructures under hybrid uncertainties', Materials & Design, vol. 205, pp. 109728-109728.
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Zhong, J, Kirby, R, Karimi, M & Zou, H 2021, 'A cylindrical expansion of the audio sound for a steerable parametric array loudspeaker', The Journal of the Acoustical Society of America, vol. 150, no. 5, pp. 3797-3806.
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In this work, a cylindrical expansion for the audio sound generated by a steerable baffled parametric array loudspeaker (PAL) based on the phased array technique is derived from the Westervelt equation. The expansion is a series of twofold summations with uncoupled angular and radial components in the cylindrical coordinate system. The angular component is determined by the trigonometric functions, and the radial component is an integral containing the Bessel functions and an arbitrary excitation velocity profile. The numerical results for a typical steerable PAL are presented and compared to those obtained using the convolution model. It is found that the prediction of the audio sound using the proposed cylindrical expansion improves the agreement with the experimental results when compared to the existing models. This is because no further approximations are required in the cylindrical expansion of the quasilinear solution of the Westervelt equation, whereas the complex near field nonlinear interactions between the ultrasonic waves cannot be correctly captured in a convolution model. The proposed cylindrical expansion does, therefore, provide an alternative approach to modeling a phased array PAL and high accuracy with a relatively low computational cost.
Zhu, M & Zhao, S 2021, 'An iterative approach to optimize loudspeaker placement for multi-zone sound field reproduction', The Journal of the Acoustical Society of America, vol. 149, no. 5, pp. 3462-3468.
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Various array patterns, such as circular, linear, and arc-shaped arrays, have been used in multi-zone sound field reproduction, but most of them are based on empirical rather than judicious selection. This article proposes an iterative optimization method to select the loudspeaker positions from a large set of candidate locations. Both the number and locations of the loudspeakers can be designed with superior performance. Both single-frequency and broadband simulations based on the acoustic contrast control method are performed to validate the proposed scheme, and the performance of the optimized array is compared with that of an arc-shaped array and that of an array optimized with an existing method.
Abbasnejad, B, Mcgloin, D & Clemon, L 1970, 'A Flexible Hair-Like Laser Induced Graphitic Sensor for Low Flow Rate Sensing Applications'.
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Akbarzadeh, M, Oberst, S, Sepehrirahnama, S & Halkon, B 1970, 'Modulated acoustic radiation force in a carrier standing wave', Acoustofluidics, Acoustofluidics, USWNet (online, virtual conference).
Aldini, S, Lai, Y, Carmichael, MG, Paul, G & Liu, D 1970, 'Real-time Estimation of the Strength Capacity of the Upper Limb for Physical Human-Robot Collaboration', 2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), IEEE, Mexico, pp. 4533-4536.
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In physical Human-Robot Collaboration (pHRC), having an estimate of the operator’s strength capacity can help implement control strategies. Currently, the trend is to integrate devices that can measure physiological signals. This is not always a viable option, especially for highly dynamic tasks. For pHRC tasks, the physical interaction point usually occurs at the operator’s hand. Therefore, a musculo-skeletal model was used to have a real-time estimation of the strength capacity of the operator’s upper limb. First, the model has been simplified to reduce the complexity of the problem. The model was used to obtain offline estimations of the strength capacity, that were then curve-fitted to enable real-time estimation. An experiment was carried out to compare the results of the approximated model with human data. Results suggest that this method for estimating the strength capacity of the upper limb is a viable solution for real-time applications.
Aldini, S, Singh, AK, Carmichael, M, Wang, Y-K, Liu, D & Lin, C-T 1970, 'Prediction-Error Negativity to Assess Singularity Avoidance Strategies in Physical Human-Robot Collaboration', 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021 IEEE International Conference on Robotics and Automation (ICRA), IEEE, Xi'an, China, pp. 3241-3247.
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In physical human-robot collaboration (pHRC), singularity avoidance strategies are often critical to obtain stable interaction dynamics. It is hypothesised a predictable singularity avoidance strategy is preferred in pHRC as humans tend to maximise predictability when using complex systems. By using an electroencephalogram (EEG), it is possible to assess the predictability of a task through a feature found in event-related potentials (ERP) and called prediction-error negativity (PEN). In this paper, two research questions are addressed. Can a complex pHRC singularity avoidance strategy generate a detectable PEN? Are PEN and human preferences related when comparing different control settings in a singularity avoidance strategy? Fourteen participants compared two different sets of parameters (modes) in a singularity avoidance strategy based on the exponentially damped least-squared (EDLS) method. ERP results are presented in terms of power spectral density (PSD). ERP results were then compared with human preferences to see whether they are related. Results show that the mode that causes PEN is also the one that participants did not like, suggesting that a lack of predictability might have an impact on human preference.
Banuelos, DP, Falque, R, Patten, T & Alempijevic, A 1970, 'Skirting Line Annotation via Deformation Modelling', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, Melbourne, VIC.
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Automating the process of wool handling has the potential to drastically improve the productivity of on-farm operations that would result in significant cost savings for wool growers. Towards this goal, we present a method to automatically extract the skirting line (i.e., the separation between clean and contaminated wool) by comparing pre- and post-skirted RGB images of freshly shorn wool fleece. The intention is to provide annotation to support downstream learning methods. Our approach detects feature correspondences then performs non-rigid outlier rejection to overcome the challenge of deformation when the wool is handled. The final alignment, and hence identification of the skirting line, is achieved through the use of a non-rigid deformation method. A controlled experiment shows, quantitatively, that our approach outperforms a rigid registration baseline. We then demonstrate the applicability to the real use case by presenting qualitative results on images of skirted fleeces collected from a wool shed.
Bhowmick, S, Saha, GK, Xu, F & Saha, SC 1970, '2D study of the bifurcations in a V-shaped cavity', Proceedings of the 13th International Conference on Mechanical Engineering (ICME2019), Proceedings of the 13th International Conference on Mechanical Engineering (ICME2019), AIP Publishing.
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Byun, H, Kim, J, Liu, D & Woolfrey, J 1970, 'Towards a Pantograph-based Interventional AUV for Under-ice Measurements', Australasian Conference on Robotics and Automation, ACRA.
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This paper addresses the design of a novel interventional robotic platform, aiming to perform an autonomous sampling and measurement under the thin ice in the Antarctic environment. We propose a pantograph mechanism, which can effectively generate a constant interaction force to the surface during the contact, which is crucial for reliable measurements. We provide the proof-of-concept design of the pantograph with a robotic prototype with foldable actuation. Preliminary results of the pantograph mechanism and the localisation system are provided, confirming the feasibility of the system.
Chen, S, Han, R, Zhao, L, Hang, S & Hao, Q 1970, 'Multi-robot Feature-based SLAM using Submap Joining', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, ARAA, Melbourne, Australia, pp. 1-8.
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This paper considers the feature-based SLAM using multiple robots. To reduce the computational complexity and data storage, a distributed multi-robot feature-based SLAM algorithm under submap joining scheme is proposed. Each robot first independently builds a submap using the information collected by its sensors. Once the robots can observe each other, the submaps can then be fused together to obtain a global map. We implemented and tested the proposed algorithm in both simulation and real world environments. Both simulation and experimental results have validated the robustness and accuracy of the proposed algorithm.
Clemon, L 1970, 'Directed Graphical Model for Real-Time Process Monitoring in Additive Manufacturing'.
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Clemon, L & Christopher, K 1970, 'Increased Strength of 3D Printed Parts With Z-Pin Approach', Volume 2A: Advanced Manufacturing, ASME 2021 International Mechanical Engineering Congress and Exposition, American Society of Mechanical Engineers.
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Abstract Current extrusion-based 3D printing technologies adopt a layer-by-layer material deposition approach which is equivalent to stacking layers of material. This traditional 2.5D deposition plan is limited to depositing discrete, cross-sectional layers of the model. Such stacked layers are well known to induce anisotropic material behavior subject to part orientation during fabrication. Parts are loaded in their build direction (perpendicularly to layers), have up to a 50% decrease in tensile strength, and a significant 95% decrease in toughness when compared to x-y plane loading. In this work, we adopt a z-pinning approach inspired by traditional composite manufacturing methods to create cross-layer pins for part reinforcement. Our z-pins aim to reinforce the weaker interfaces between 3D printed layers, by facilitating stronger layer adhesion and by obstructing crack propagation through the planar structure of traditional 3D prints. This adaptation of the pin reinforcement concept for 3D printing is implemented on a consumer-grade Fused Filament Fabrication machine without the need for additional hardware. The fabrication machine is a standard linear 3-axis gantry design with off-the-shelf components. We create a custom workflow for editing the part mesh and toolpath plan that is inserted in the workflow between open-source slicing of the part file and part fabrication by the machine. This reads and edits the g-code instructions to insert the z-pin reinforcements into the existing deposition plan. A total of thirty-six tensile and flexural test specimens were fabricated using Polylactic Acid filament (PLA). The depth of the reinforcement pins, pin spacing, infill percentage, and the orientation of the build are perturbed to evaluate the effectiveness of the method. Tests were conducted on a calibrated Instron ElectroPuls E10000 using standard rectilinear test sample geometries. Test results show pinn...
Cuciti, S & Halkon, B 1970, 'Vibration Analysis of Robotic End Effector Components for Industrial Scale Microlithography', 10th Australian Congress on Applied Mechanics.
Cullen, M, Zhao, S & Ji, JC 1970, 'Acoustic based classification of transfer modes in gas metal arc welding', Annual Conference of the Australian Acoustical Society 2021: Making Waves, AAS 2021, pp. 51-57.
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Gas Metal Arc Welding (GMAW) is a welding process which involves forming an electric arc between a consumable wire electrode and a metal work piece while protecting the arc from contaminants using a shielding gas. In this form of welding, there are several varying ways in which the molten droplets can be transferred from the end of the welding wire into the weld pool known as transfer modes. Identifying these transfer modes is crucial in monitoring and controlling the welding process, especially in automated applications such as industry 4.0 manufacturing lines. Currently in industry, these transfer modes can be identified by expert welders by using the sound signal that is generated throughout the welding process. However, there has been limited research on using the acoustic signal to detect these transfer modes in automated welding applications.This paper explores a new method of automatic GMAW transfer mode detection using machine learning techniques to analyse the acoustic signal generated during the welding process. Several time and frequency domain features are extracted from the acoustic signal and used to train a support vector machine classifier to accurately classify the transfer modes. In addition to this, a new feature selection algorithm is proposed to improve the prediction accuracy of the support vector machine classifier and a final prediction rate of 94% was achieved. This high prediction rate demonstrates the feasibility and promising accuracy of using the acoustic signal as a basis for transfer mode classification in future smart welding technology with real-time adaptive feedback control.
D'Urso, G, Heon Lee, JJ, Pizarro, O, Yoo, C & Fitch, R 1970, 'Hierarchical MCTS for Scalable Multi-Vessel Multi-Float Systems', 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021 IEEE International Conference on Robotics and Automation (ICRA), IEEE.
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Eager, D, Hossain, MI, Lind, E & Ishac, K 1970, 'Unattenuated vertical walls in trampoline parks are Safer than attenuated vertical walls', Congress of the European Society of Biomechanics, Congress of the European Society of Biomechanics, Milan, Italy.
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This paper discusses a novel use of vibration equipment to assess the safety of whether to pad or not to pad the vertically orientated walls within trampoline parks used specifically for an activity known as walk-the-walk.The CEN/TC 136 WG 17 is currently drafting EN ISO 23695:202x Trampoline Parks – Safety requirements. The joint CEN/ISO Working Group is divided on whether to allow a padded or rigid vertical surface for the walk-the-walk activity. In general, all surfaces within the falling space of a forced movement device such as a trampoline shall be impact attenuated.This paper presents the finding of research undertaken by the University of Technology Sydney to provide the CEN/ISO Working Group with guidance.The walk-the-walk activity is where a trampolinist walks up a vertical wall using a high-performance trampoline to obtain sufficient vertical height and momentum.
Edwards, R & Clemon, L 1970, 'Influencing the Mechanical Properties of Fused Filament Fabrication Parts by Non-Planar Material Extrusion', Volume 2A: Advanced Manufacturing, ASME 2021 International Mechanical Engineering Congress and Exposition, American Society of Mechanical Engineers.
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Abstract Current applications of Fused Filament Fabrication in additive manufacturing tend to produce heavily anisotropic parts. This is largely due to the discretisation of heterogeneous planar layers, resulting in surface artefacts, stress concentrations and weak thermal fusion bonding that fundamentally limit the strength of end-use parts. In an effort to improve the mechanical properties of parts produced by Fused Filament Fabrication, this work developed a novel method by which to implement non-planar toolpath generation for a conventional three-axis machine. Utilising Boolean-based mesh approaches, arbitrary sinusoidal surfaces were used to generate non-planar tool-paths for the test specimens. To do so, a point cloud representing a non-planar surface was triangulated to form a surface mesh. A Boolean intersection between this non-planar surface mesh and the specimen mesh was then used to return the non-planar surface bounded by the geometry of the specimen; an edge traversal technique was then employed to obtain three-dimensional toolpaths. The frequency and amplitude of the non-planar sinusoidal surfaces were incrementally increased from the planar case until the geometric limits of the print-head were reached. Test specimens were then manufactured on a conventional three-axis machine and subject to a three-point bending test. There was a strong negative correlation between the flexural moduli of the specimens and the frequency and maximum tangential angle of their non-planar surfaces, while there was a strong positive correlation between the toughness of the specimens and the frequency of their non-planar surfaces. Non-planar specimens also exhibited more prominent yield points, and were better able to dissipate energy and resist crack propagation. A key finding was the significant increase in plastic strain exhibited by the non-planar samples; certain specimen types were able to withstand an aver...
Falque, R, Vidal-Calleja, T, McPhee, M, Toohey, E & Alempijevic, A 1970, 'VirtualButcher: Coarse-to-fine Annotation Transfer of Cutting Lines on Noisy Point Cloud Reconstruction', 2021 IEEE 21st International Symposium on Computational Intelligence and Informatics (CINTI), 2021 IEEE 21st International Symposium on Computational Intelligence and Informatics (CINTI), IEEE.
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Fattoruso, V, Oberst, S, Lai, JCS & Evans, TA 1970, 'Exploring the effects of acoustic camouflage studying termite inquiline-host relationships', XI AISASP Student Meeting, XI AISASP Student Meeting, Italy.
Furukawa, T, Steckenrider, JJ & Dissanayake, G 1970, 'State Estimation of a Partially Observable Multi-Link System with No Joint Encoders Incorporating External Dead-Reckoning', 2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), IEEE.
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Gunasekara, S, Jayasuriya, M, Harischandra, N, Samaranayake, L & Dissanayake, G 1970, 'A Convolutional Neural Network Based Early Warning System to Prevent Elephant-Train Collisions.', ICIIS, 2021 IEEE 16th International Conference on Industrial and Information Systems, IEEE, Kandy, Sri Lanka, pp. 271-276.
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One serious facet of the worsening Human-Elephant Conflict (HEC) in nations such as Sri Lanka involves elephant-train collisions. Endangered Asian elephants are maimed or killed during such accidents, which also often results in orphaned or disabled elephants. Furthermore, railway services incur significant financial losses and disruptions to services annually due to such accidents. Most elephant-train collisions occur due to a lack of adequate reaction time due to poor driver visibility at sharp turns, night-time operation, and poor weather conditions. Initial investigations also indicate that most collisions occur in localised “hotspots” where elephant pathways/corridors intersect with railway tracks. Taking these factors into consideration, this work proposes the leveraging of recent developments in Convolutional Neural Network (CNN) technology to detect elephants using an RGB/infrared capable camera, around known hotspots along the railway track. The CNN was trained using a curated dataset of elephants collected on field visits to elephant sanctuaries and wildlife parks in Sri Lanka. With this vision-based detection system at its core, a prototype unit of an early warning system was designed and tested. Initial results indicate that detection accuracy is sufficient under varying lighting situations, provided that comprehensive training datasets that represent a wide range of challenging conditions are available. The overall hardware prototype was shown to be robust and reliable. We envision a network of such units may help contribute to reducing the problem of elephanttrain collisions and has the potential to act as an important surveillance mechanism in dealing with the broader issue of the human-elephant conflict.
Gunatilake, A, Galea, M, Thiyagarajan, K, Kodagoda, S, Piyathilaka, L & Darji, P 1970, 'Using UHF-RFID Signals for Robot Localization Inside Pipelines', 2021 IEEE 16th Conference on Industrial Electronics and Applications (ICIEA), 2021 IEEE 16th Conference on Industrial Electronics and Applications (ICIEA), IEEE, pp. 1109-1114.
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Underground water pipes are important to any country's infrastructure. Overtime, the metallic pipes are prone to corrosion, which can lead to water leakage and pipe bursts. In order to prolong the service life of those assets, water utilities in Australia apply protective pipe linings. Long-term monitoring and timely intervention are crucial for maintaining those lining assets. However, the water utilities do not possess the comprehensive technology to achieve it. The main reasons for lacking such technology are the unavailability of sensors and accurate robot localization technologies. Feature based localization methods such as SLAM has limited use as the application of liners alters the features and the environment. Encoder based localization is not accurate enough to observe the evolution of defects over a long period of time requiring unique defect correspondence. This motivates us to explore accurate contact-less and wireless based localization methods. We propose a cost-effective localization method using UHF-RFID signals for robot localization inside pipelines based on Gaussian process combined particle filter. Experiments carried out in field extracted pipe samples from the Sydney water pipe network show that using the RSSI and Phase data together in the measurement model with particle filter algorithm improves the localization accuracy up to 15 centimeters precision.
Gunatilake, A, Thiyagarajan, K & Kodagoda, S 1970, 'Evaluation of Battery-free UHF-RFID Sensor Wireless Signals for In-pipe Robotic Applications', 2021 IEEE Sensors, 2021 IEEE Sensors, IEEE.
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Halkon, B 1970, 'Making waves in vibration measurement with laser Doppler vibrometry', Annual Conference of the Australian Acoustical Society 2021: Making Waves, AAS 2021, pp. 391-392.
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The impact of the invention of the laser cannot be over-stated. In vibration and acoustics engineering, the laser Doppler vibrometer has revolutionised the means by which scientists and engineers can interpret and control the natural and man-made environment, both on and off the planet. Combining high sensitivity, dynamic and frequency ranges, non-invasiveness and high spatial resolution, laser Doppler vibrometers (LDVs) have received significant and increasing attention in both research and industry. This paper will briefly investigate the origins, working principles and evolution of LDVs, focusing on industrially relevant, practical applications. Particular focus will be on overcoming specific challenges associated with making successful measurement campaigns in challenging scenarios, including directly from rotating equipment and from vibrating platforms, a UTS topic of interest.
Halkon, B & Eager, D 1970, 'Acoustic measurements of the murray bridge greyhound racing track lure systems', 'Advances in Acoustics, Noise and Vibration - 2021' Proceedings of the 27th International Congress on Sound and Vibration, ICSV 2021, 27th International Congress on Sound and Vibration, Prague.
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This study investigated preliminary acoustical recordings that were conducted at the Murray Bridge greyhound racing track. The purpose of the investigation was to undertake a feasibility study to subsequently collect more detailed measurements of the acoustic signatures of a traditional cable driven lure system and compare and contrast these with two alternative, battery-operated lure systems under development by Steriline Racing. This paper comprehensively reports the measurement campaign conducted - including the various environmental, practical and logistical challenges - and offers an early insight into the different nature of the acoustical signals observed for the three lure systems. Future work will include better integration between measurement and lure/track control systems, yielding higher quality, more readily handled signals, with more sophisticated processing techniques.
Han, S, Ji, JC & Ye, K 1970, 'Elimination of High-Frequency Whistle Noise in a Residential Ducted Air-Conditioning System Using a Dedicated Pipe Muffler Design', Springer International Publishing, pp. 11-19.
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Hanna, P, Carmichael, M & Clemon, L 1970, 'Development of an Organisational Framework for the Optimal and Efficient Selection of Actuators', Volume 5: Biomedical and Biotechnology, ASME 2021 International Mechanical Engineering Congress and Exposition, American Society of Mechanical Engineers, Virtual.
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Abstract Actuators are a vital component, and more often than not one of the limiting factors in robotics and robotics related applications. For the use of actuators in robotics related to humanoids, exoskeletons, prosthetics and orthoses, there are more factors that influence the selected actuator than the basic mechanical outputs, size, backlash, material and power consumption. The main interest within these applications is that because the device is being carried by the human user, thus weight, power consumption and form factor are important selection parameters. The correct selection of an actuator for these applications is a difficult and lengthy process to perform. This paper creates an organizational framework and database for searching the wide range of actuators. This dataset is organized into a design tool that plots the properties of each actuator on varying graphs creating trade-off Ashby charts to rapidly narrow the selection space for designers. A case study is performed to demonstrate the use of this design tool in human-centric actuation applications. The database is utilized in the selection of the ideal actuator based on lines of best fit and a multivariate regression analysis for the optimization of parameters about the required specifications. In addition, a meta-analysis identifies clusters of current actuators, gaps for new developments, and trends. This work provides research direction into developing specific actuators to fit into these trend gaps which offers substantial benefits to humanoids, exoskeletons, prosthetics and orthosis.
Hanson, D, Wolfgang, B, Williams, P, Kirby, R & Neville, M 1970, 'Engine Exhaust Silencers for Older Locomotives - a Case Study', Annual Conference of the Australian Acoustical Society 2021: Making Waves, AAS 2021, pp. 383-390.
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Mitigating engine exhaust noise from older locomotives is a substantial challenge. The engine noise is broadband, but also includes prominent low-frequency tones that vary with engine speed. There is very little space inside the locomotive, so while a silencer would ideally be as large as possible, it must fit within tight constraints around other locomotive equipment. Many older locomotives have two-stroke engines that are highly sensitive to back pressure and were designed to run with direct ventilation to atmosphere. This imposes tight constraints on the flow resistance that a silencer can introduce, thereby constraining the design options. This paper presents a successful case study in mitigating engine noise from an older locomotive. A team of Hushpak Engineering, UTS Tech Lab and Acoustic Studio designed, built and commissioned silencers for the C Class locomotives. The paper discusses how the design challenges of space, back-pressure and low-frequency tones were addressed. It also describes how developing the acoustic solution was not enough to deliver a successful project. The team had also to design and implement an upgraded crankcase ventilation system to maintain correct engine operation with the silencer in place. This project showed that silencers for older locomotives can be efficient, effective and inexpensive, and highlights a way forward for addressing noise across the fleet of older locomotives that will remain in service for years to come.
Henke, T & Deuse, J 1970, 'Applying Packing Problems to Optimize Throughput Time and Human Ergonomics in Project Shops', Springer International Publishing, pp. 92-99.
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Huang, S, Chen, Y, Zhao, L, Zhang, Y & Xu, M 1970, 'Some Research Questions for SLAM in Deformable Environments', 2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), IEEE.
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Ishac, K & Eager, D 1970, 'Injuries in Greyhound Racing: Number of Starters', 26th Congress of the European Society of Biomechanics, 26th Congress of the European Society of Biomechanics, Virtual.
Islam, MZ, Hossain, SI, Deplazes, E, Bhowmick, S & Saha, SC 1970, 'Molecular dynamics study of prednisolone concentration on cholesterol based lung surfactant monolayer', Proceedings of the 13th International Conference on Mechanical Engineering (ICME2019), Proceedings of the 13th International Conference on Mechanical Engineering (ICME2019), AIP Publishing, p. 060008.
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Jenkin, L, Peng, J & Parnell, J 1970, 'Comparison of five general noise prediction models and their performance in estimating low frequency noise propagation', Annual Conference of the Australian Acoustical Society 2021: Making Waves, AAS 2021, pp. 106-107.
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Predicting noise impact is a valuable tool for acoustic consultants. In Australia, five common models are used to determine the propagation loss from a source to a receiver; being ISO-9613-2, CONCAWE, ENM, CNOSSOS-EU, and NORD2000. Emissions data for common construction equipment is used to compare the predicted A and C-weighted levels from these models to show there are large differences in predictions, even for simple scenarios.
Kalhori, H, Halkon, B, Abbasnejad, B, Li, B & Shooshtari, A 1970, 'Nonlinear Vibration of an Electrostatically Excited Capacitive Microplate', Springer, 2020, Asia-Pacific Vibration Conference, Springer International Publishing, University of Technology Sydney UTS, Sydney, Australia, pp. 3-9.
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This study aims at understanding the transient vibration of an electrostatically excited microplate considering the effects of different boundary conditions. The partial differential equations of motion of rectangular microplate-based microelectromechanical systems (MEMS) are derived within the framework of the classical plate theory and von Kármán geometric nonlinearity. The nonlinear terms are due to the electrostatic force nonlinearity and the mid-plane stretching of the plate. The Galerkin procedure is used to obtain a second-order nonlinear ordinary differential equation in time with quadratic, cubic, quartic, and higher-order nonlinear terms. Attention is focused mainly on the method of elimination of singularity in the electrostatic force; two methods are proposed to treat the singularity. It is indicated that for nondimensional voltages lower than 75, both methods give rise to a similar system response. Finally, an analytical expression representing the transient dynamic behavior of the system is proposed. Experimental verification will be conducted in the next phase of the study.
Kiss, SH, Katuwandeniya, K, Alempijevic, A & Vidal-Calleja, T 1970, 'Probabilistic Dynamic Crowd Prediction for Social Navigation', 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021 IEEE International Conference on Robotics and Automation (ICRA), IEEE.
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Lai, Y, Sutjipto, S, Carmichael, MG & Paul, G 1970, 'Preliminary Validation of Upper Limb Musculoskeletal Model using Static Optimization', 2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), IEEE, Mexico, pp. 4509-4512.
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Musculoskeletal models are powerful analogues to simulate human motion through kinematic and dynamic analysis. When coupled with feature-rich software, musculoskeletal models form an attractive platform for the integration of machine learning for human motion analysis. Performing realistic simulations using these models provide an avenue to overcome constraints when collecting real-world data sets. This motivates the need to further investigate the validity, efficacy, and accuracy of each available model to ensure that the resultant simulations are transferable to real-world applications. Using the open-source software, OpenSim, the primary aim of this paper is to validate an upper limb musculoskeletal model widely used in research. Muscle activation results from static optimization are evaluated against real-world data. A secondary aim is to investigate the effects of two muscle force generation constraints when evaluating the model’s validity. Results show an agreement between the optimized muscle activation trends and real-world sEMG readings. However, it was found that static optimization of the musculoskeletal model is unable to identify voluntary co-contractions since the redundant model has more muscles than the system’s degrees of freedom. Thus, future work will look to utilize additional channels of information to incorporate this during analysis.
Lee, CYH, Best, G & Hollinger, GA 1970, 'Optimal Sequential Stochastic Deployment of Multiple Passenger Robots', 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021 IEEE International Conference on Robotics and Automation (ICRA), IEEE.
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Lee, CYH, Best, G & Hollinger, GA 1970, 'Stochastic Assignment for Deploying Multiple Marsupial Robots', 2021 International Symposium on Multi-Robot and Multi-Agent Systems (MRS), 2021 International Symposium on Multi-Robot and Multi-Agent Systems (MRS), IEEE.
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Liu, D, Peng, J, Parnell, J & Kessissoglou, N 1970, 'A GIS-based heavy vehicle noise emission model', Annual Conference of the Australian Acoustical Society 2021: Making Waves, AAS 2021, pp. 395-396.
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Prediction of road traffic noise is important for environmental impact assessments. In this work, a GIS-based heavy vehicle noise emission model is presented. The GIS-based model accounts for the influence of translational vehicle dynamics for a heavy vehicle on grade to enable accurate prediction of vehicle speed as well as operating conditions such as acceleration and deceleration. These kinematic variables in turn assist with accurate estimation of engine noise and rolling noise. To illustrate the model, a case study based on a freight route of the Great Western Highway in New South Wales is presented.
Mao, Z, Zhao, L, Huang, S, Fan, Y & Lee, AP-W 1970, 'Direct Bundle Adjustment for 3D Image Fusion with Application to Transesophageal Echocardiography', 2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), IEEE, Prague, Czech Republic, pp. 548-554.
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In this paper, we propose a novel algorithm for fusing a sequence of 3D images, named as Direct Bundle Adjustment (DBA). This algorithm simultaneously optimizes the global pose parameters of image frames and the intensity values of the fused global image using the 3D image data directly (without extracting features from the images). This one-step 3D image fusion approach is achieved by formulating the problem as an optimization problem to minimize the intensity differences between the global image and the corresponding points in the different local images. The proposed DBA method is particularly useful in the scenarios where distinct features are not available, such as Transesophageal Echocardiography (TEE) images. We validate the proposed method via simulated and in-vivo 3D TEE images. It is shown that the proposed method is robust to intensity noises and much more accurate than the conventional sequential fusion method.
Milton, J, Hall, M, Chiang, YK, Halkon, B, Oberst, S & Powell, D 1970, 'Exploring the effect of underwater burial on the resonant behaviour of simplified shell geometries', Annual Conference of the Australian Acoustical Society 2021: Making Waves, AAS 2021, Australian Acoustics Society - Acoustics 2021, Wollongong, pp. 15-22.
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Naval mines and unexploded ordnance litter large areas of the ocean floor resulting in many coastlines being abandoned due to their deadly and indiscriminate threat. Over time, many become buried within the seabed, becoming less visible and thereby presenting a challenge to existing image-based detection techniques. Alternative approaches might rely on acoustic scattering, and it is therefore necessary to understand how the signatures of such objects may change when burial occurs. In this paper, the scattering spectra of several simple shell geometries have been evaluated through complementary but independently developed numerical and analytical modelling techniques. Scenarios investigated include air and fluid-filled spherical targets surrounded either by seawater or saturated sand, representative of burial within the seabed. The results show how embedding the objects within saturated sand results in a decrease in frequency of the dominant scattering resonances. In general, these frequencies were reduced by a factor of between 1.2 and 1.4.
Munasinghe, N, Masangkay, J & Paul, G 1970, 'Temperature Compensated 3D Printed Strain Sensor for Advanced Manufacturing Applications', 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021 IEEE International Conference on Robotics and Automation (ICRA), IEEE, Xi’an China.
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Nerse, C & Wang, S 1970, 'Modeling of Complex Modes with Wave-Based Scaling', Vibration Engineering for a Sustainable Future, Springer International Publishing, pp. 25-29.
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Nerse, C, Schadeberg, R & Oberst, S 1970, 'Novel resonator geometry for easily manufactured tunable locally resonant metamaterial', Annual Conference of the Australian Acoustical Society 2021: Making Waves, AAS 2021, Annual Conference of the Australian Acoustical Society, AAS, Wollongong, Australia, pp. 68-72.
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Mechanical waves and sound waves have complex propagation characteristics that are manipulated by periodic structures such as elastic metamaterials and phononic crystals for the purposes of wave guiding, vibration isolation and sound absorption. System parameters are tuned to induce auxetic physical properties such as negative effective mass density and negative Poisson's ratio. Locally resonant metamaterial (LRM) uses Fano-type interference to manipulate elastic wave propagation from the host structure by formation of a band gap due to local resonance. Not restricted by the Bragg interference limit, such sub-wavelength structures are particularly effective in attenuation of the low frequency oscillations. Tunability of the lower and upper bounds of the band gap through simple geometrical and material variations has made the LRMs a strong candidate for the noise and vibration control of automotive and industrial applications. In this study, we demonstrate a tunable LRM design that can be fabricated by injection moulding and vacuum casting. The mould for the fabrication of the resonator features a cylindrical hollow section. Pins of different diameter can be inserted into the mould to vary the material distribution in the cavity, thereby changing the resonance. A numerical model using COMSOL Multiphysics has been developed to investigate the dispersion mechanism. A parametric study of the pin diameter with respect to target band gap frequency demonstrates the capability of broadband vibration attenuation while keeping the overall size of the resonator small and constant. These results are promising for practical implementation of LRMs.
Nguyen, L, Thiyagarajan, K, Ulapane, N & Kodagoda, S 1970, 'Multimodal Sensor Selection for Multiple Spatial Field Reconstruction', 2021 IEEE 16th Conference on Industrial Electronics and Applications (ICIEA), 2021 IEEE 16th Conference on Industrial Electronics and Applications (ICIEA), IEEE, pp. 1181-1186.
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The paper addresses the multimodal sensor selection problem where selected colocated sensor nodes are employed to effectively monitor and efficiently predict multiple spatial random fields. It is first proposed to exploit multivariate Gaussian processes (MGP) to model multiple spatial phenomena jointly. By the use of the Matérn cross-covariance function, cross-covariance matrices in the MGP model are sufficiently positive semi-definite, concomitantly providing efficient prediction of all multivariate processes at unmeasured locations. The multimodal sensor selection problem is then formulated and solved by an approximate algorithm with an aim to select the most informative sensor nodes so that prediction uncertainties at all the fields are minimized. The proposed approach was validated in the real-life experiments with promising results.
Nguyen, L, Thiyagarajan, K, Ulapane, N & Kodagoda, S 1970, 'Multivariate versus Univariate Sensor Selection for Spatial Field Estimation', 2021 IEEE 16th Conference on Industrial Electronics and Applications (ICIEA), 2021 IEEE 16th Conference on Industrial Electronics and Applications (ICIEA), IEEE, pp. 1187-1192.
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The paper discusses the sensor selection problem in estimating spatial fields. It is demonstrated that selecting a subset of sensors depends on modelling spatial processes. It is first proposed to exploit Gaussian process (GP) to model a univariate spatial field and multivariate GP (MGP) to jointly represent multivariate spatial phenomena. A Matérn cross-covariance function is employed in the MGP model to guarantee its cross-covariance matrices to be positive semi-definite. We then consider two corresponding univariate and multivariate sensor selection problems in effectively monitoring multiple spatial random fields. The sensor selection approaches were implemented in the real-world experiments and their performances were compared. Difference of results obtained by the univariate and multivariate sensor selection techniques is insignificant; that is, either of the methods can be efficiently used in practice.
Nikoloska, R, Vitanage, D, Bykerk, L, Valls Miro, J, Liang, B, Xu, J & Wang, Y 1970, 'Advances in Leak Prevention to Minimise Unaccounted Water', Australia's International Water Conference and Exhibition, OzWater'21 Australia's International Water Conference and Exhibition, Adelaide.
Panusch, T, Möhle, R, Zwinkau, R & Deuse, J 1970, 'Reduction of Human Effort in Technical Cleanliness Inspection Through Advanced Image Processing Approaches', Springer International Publishing, pp. 108-115.
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Patten, T, Alempijevic, A & Fitch, R 1970, 'Learning Image-Based Contaminant Detection in Wool Fleece from Noisy Annotations', Computer Vision Systems, Springer International Publishing, pp. 234-244.
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This paper addresses the problem of detecting natural contaminants in freshly shorn wool fleece in RGB images using deep learning-based semantic segmentation. The challenge of inconsistent annotation is overcome by learning the probability of contamination as opposed to a discrete class. From the continuous value predictions, contaminated regions can be extracted by selectively thresholding on the probability of contamination. Furthermore, the imbalance of the class distributions is accounted for by adaptively weighting each pixel’s contribution to the loss function. Results show that the adaptive weight improves the prediction accuracy and overall outperforms learning an approximated representation by quantising the distributions.
Patten, T, Park, K, Leitner, M, Wolfram, K & Vincze, M 1970, 'Object Learning for 6D Pose Estimation and Grasping from RGB-D Videos of In-hand Manipulation', 2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2021 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), IEEE.
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Richter, R, Deuse, J, Willats, P, Syberg, M & Lenze, D 1970, 'Managing Variability in Production', IFIP Advances in Information and Communication Technology, International-Federation-of-Information-Processing-Working-Group-5.7 (IFIP WG 5.7) International Conference on Advances in Production Management Systems (APMS), Springer International Publishing, ELECTR NETWORK, pp. 730-738.
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The corresponding author worked for many years with Toyota coaches, supporting Bosch in the development of pilot value streams for the Bosch Production system. The coaches spent considerable time and effort to analyze and decouple production from customer fluctuations and to stabilize the flow of production with adequate inventory buffers and capacity. The project team, on the other hand, was impatient, wanting to redesign lines, install Kanban and perform Kaizen activities. They did not understand that their coach was reducing unevenness and overload, so called Mura and Muri, striving for basic stability, as a precondition for lean activities. Later, they denoted a line possessing this basic stability in Bosch as an “improvable system”. In this paper the authors develop methods to analyze and reduce variability in value streams. The value stream is divided into zones, which are then qualified as stable or unstable. Measures are introduced to turn unstable into stable zones, step by step, enabling sustainable improvement activities in those stabilized zones. An IT system is developed to acquire and process the vast amount of data needed for variability measurements, and to provide structured information to support the management of variability in production.
Rudorf, M, Oberst, S, Stender, M & Hoffmann, N 1970, 'Bifurcation Analysis of a Doubly Curved Thin Shell Considering Inertial Effects', Vibration Engineering for a Sustainable Future, Asia-Pacific Vibration Conference, Springer International Publishing, Australia, pp. 51-57.
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Thin-elastic structures can be found in nature as well as in many technical applications, including plant material (leaves) or insect appendages (wings) and aircraft outer bodies, optical mirrors and membranes, solar panels or satellite antennas. Numerical modelling of those structures is commonly conducted using shell elements. Especially doubly curved shells have found much attention due to their applicability in thin shell or sandwich structures used in the automotive, aerospace and space industry. In the design process it is generally assumed that these structures behave linearly, however, considering their curvature and how thin they are, large deflections easily become an issue as shown experimentally. Yet, the numerical modelling does conventionally assume that inertia e ffects can be neglected. Here we derive the equations of motion of a simply supported configuration of a doubly curved shell with 9 degrees of freedom with and without inertial coupling terms. We show by conducting a bifurcation analysis that the additional inertia effects cannot be neglected and that care has to be taken when structures as such are being employed as appendages on real-life satellites.
Saha, SC & Islam, MS 1970, 'Airflow and Particle Transport to the Terminal Bronchioles During Heliox Breathing', Springer Singapore, pp. 535-544.
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Scheide, E, Best, G & Hollinger, GA 1970, 'Behavior Tree Learning for Robotic Task Planning through Monte Carlo DAG Search over a Formal Grammar', 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021 IEEE International Conference on Robotics and Automation (ICRA), IEEE.
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Schlegl, T, Schlegl, S, Sciberras, A, West, N & Deuse, J 1970, 'Margin-based Greedy Shapelet Search for Robust Time Series Classification of Imbalanced Data', 2021 IEEE International Conference on Big Data (Big Data), 2021 IEEE International Conference on Big Data (Big Data), IEEE, Orlando, FL, USA, pp. 5266-5274.
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Many real-world big data applications in domains like finance, telecommunication and manufacturing rely on the detection of exceedingly rare patterns in large time series data sets. In principle, machine learning models can be trained to detect and classify such patterns. However, these models often lack the necessary robustness for practical applications and do not generalize well in production. Additionally, their intransparent decision-making hampers systematic debugging and improvement. Time series shapelets are a popular data mining primitive that can be used to extract a shape-based feature representation from the data. However, existing algorithms do not adequately consider the robustness and redundancy of these features. While these drawbacks can be compensated if sufficient labeled data is available, this is not possible for highly imbalanced data. We propose alterations to the current state-of-the-art shapelet algorithm that consider the margin of separation and the multivariate dependencies between the extracted features. This results in more robust and diverse features, which in turn translates to higher classification accuracy. We compare our algorithm to the current state-of-the-art using a public benchmark data set. Additionally, we showcase its applicability to highly imbalanced data using a suitable data set from the manufacturing domain.
Schlegl, T, Schlegl, S, West, N & Deuse, J 1970, 'Scalable anomaly detection in manufacturing systems using an interpretable deep learning approach', Procedia CIRP, Conference on Manufacturing Systems, Elsevier BV, Athens, Greece, pp. 1547-1552.
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Anomaly detection in manufacturing systems has great potential for the prevention of critical quality faults. In recent years, unsupervised deep learning has shown to frequently outperform conventional methods for anomaly detection. However, tuning, deploying and debugging deep learning models is a time-consuming task, limiting their practical applicability in manufacturing systems. We approach this problem by developing a deep learning model that learns interpretable shapes that can be used for anomaly detection in temporal process data. Application of the model to assembly tightening processes in the automotive industry shows a significant improvement in model interpretability and scalability.
Sepehrirahnama, S, Oberst, S, Chiang, YK & Powell, D 1970, 'Effects of shape and Willis coupling on acoustic radiation force and torque, Acoustic traps revisited!', Acoustofluidics, USWNet (online, virtual conference).
Sutjipto, S, Woolfrey, J, Carmichael, MG & Paul, G 1970, 'Cartesian Inertia Optimization via Redundancy Resolution for Physical Human-Robot Interaction', 2021 IEEE 17th International Conference on Automation Science and Engineering (CASE), 2021 IEEE 17th International Conference on Automation Science and Engineering (CASE), IEEE, Lyon, France, pp. 570-575.
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The objective of introducing robotic manipulators into human-centric domains is to improve the efficacy of tasks in a safe and practical manner. The shift toward collaborative manipulator platforms has facilitated physical human-robot interaction (pHRI) in such environments. Often, these platforms are kinematically redundant and possess more degrees of freedom (DOF) than needed to complete a desired task. When no additional task is defined, it is possible for the manipulator to converge upon joint configurations that are unfavourable for the collaborative task. Consequently, there is potential for the posture of the manipulator to affect the interaction experienced. This paper investigates an inertia-based optimization control method for redundant manipulators interacting with an active agent. The inertia-based reconfiguration is evaluated through simulations and quantified with real-life experiments conducted with a robot-robot dyad. It was found that resolving redundancy to reconfigure the Cartesian inertia reduced the energy expenditure of the active agent during the interaction.
Ulapane, N, Thiyagarajan, K & Kodagoda, S 1970, 'Gaussian Process As a Benchmark for Optimal Sensor Placement Strategy', 2021 IEEE Sensors, 2021 IEEE Sensors, IEEE.
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Ulapane, N, Thiyagarajan, K, Kodagoda, S & Nguyen, L 1970, 'D-Optimal Design for Information Driven Identification of Static Nonlinear Elements', 2021 IEEE 16th Conference on Industrial Electronics and Applications (ICIEA), 2021 IEEE 16th Conference on Industrial Electronics and Applications (ICIEA), IEEE, Chengdu, China, pp. 492-497.
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Identification of static nonlinear elements (i.e., nonlinear elements whose outputs depend only on the present value of inputs) is crucial for the success of system identification tasks. Identification of static nonlinear elements though can pose several challenges. Two of the main challenges are: (1) mathematical models describing the elements being unknown and thus requiring black-box identification; and (2) collection of sufficiently informative measurements. With the aim of addressing the two challenges, we propose in this paper a method of predetermining informative measurement points offline (i.e., prior to conducting experiments or seeing any measured data), and using those measurements for online model calibration. Since we deal with an unknown model structure scenario, a high order polynomial model is assumed. Over fit and under fit avoidance are achieved via checking model convergence via an iterative means. Model dependent information maximization is done via a D-optimal design of experiments strategy. Due to experiments being designed offline and being designed prior to conducting measurements, this method eases off the computation burden at the point of conducting measurements. The need for in-the-loop information maximization while conducting measurements is avoided. We conclude by comparing the proposed D-optimal design method with a method of in-the-loop information maximization and point out the pros and cons. The method is demonstrated for the single-input-single-output (SISO) static nonlinear element case. The method can be extended to MISO systems as well.
Vu, TL, Le, DT, Nguyen, DDK, Sutjipto, S & Paul, G 1970, 'Investigating the Effect of Sensor Data Visualization Variances in Virtual Reality', Proceedings of the 27th ACM Symposium on Virtual Reality Software and Technology, VRST '21: 27th ACM Symposium on Virtual Reality Software and Technology, ACM.
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West, N, Gries, J, Brockmeier, C, Gobel, JC & Deuse, J 1970, 'Towards integrated Data Analysis Quality: Criteria for the application of Industrial Data Science', 2021 IEEE 22nd International Conference on Information Reuse and Integration for Data Science (IRI), 2021 IEEE 22nd International Conference on Information Reuse and Integration for Data Science (IRI), IEEE, Las Vegas, NV, USA, pp. 131-138.
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The application of Industrial Data Science in context of connected Smart Products requires modeling and structuring data for its design, development and use. Especially for Smart Products, a comprehensive handling of data quality is mandatory, because of their interdisciplinary character and broad range of heterogeneous stakeholders covering the entire product lifecycle. The overall goal of data preparation is to provide high-quality data for application and evaluation by users. Established process models for industrial data analysis often treat the specification and assurance of data quality as a single-point activity with a defined conclusion. Providing end-to-end data quality has received little attention in the field of industrial data analytics. In this paper, we will (1) structure four distinct phases for ensuring end-to-end data quality along data analytics activities, (2) define a set of criteria and measures for meeting and quantifying data quality requirements based on established criteria, and (3) provide a step-by-step model for establishing and maintaining high Data Quality for Industrial Data Science applications. The quality criteria aim to identify pointwise and continuous actions during the data analysis process. Such criteria target a shared responsibility for maintaining data quality during analyses between analyst and user. The developed model provides an actionable approach for assessing and ensuring the requirements of Data Analysis Quality.
WEST, N, SCHLEGL, T & DEUSE, J 1970, 'Feature extraction for time series classification using univariate descriptive statistics and dynamic time warping in a manufacturing environment', 2021 IEEE 2nd International Conference on Big Data, Artificial Intelligence and Internet of Things Engineering (ICBAIE), 2021 IEEE 2nd International Conference on Big Data, Artificial Intelligence and Internet of Things Engineering (ICBAIE), IEEE, Nanchang, China, pp. 762-768.
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The decade-long trend toward process automation and end-to-end machine connectivity has fueled an enormous growth of data recorded in the manufacturing industry. Leveraging this potential requires manufacturing companies to extract actionable insights from the data sources. In particular, handling time series data on a large scale requires the use of feature extraction for dimensionality reduction. For this purpose, we propose a new algorithmic approach that uses Dynamic Time Warping to extract maximally discriminative features in a multivariate data set. A benchmark against `time series feature extraction based on scalable hypothesis tests' and state-of-the-art methods, such as InceptionTime, Convolutional Neural Network or ResNet classifier, to evaluate the overall effectiveness. While the proposed algorithm underperforms for an example data set with comparably low dimensionality, scoring 16.67% and 22.80% lower average accuracy than the benchmarks, it achieves competitive results for the real-world application in a manufacturing environment. Here, the average accuracy reaches a delta of just 12.20 % and simultaneously reduces computational effort by 97.90 %.
Williams, P, Kirby, R & Karimi, M 1970, 'Parametric study of circular duct breakout transmission loss', Annual Conference of the Australian Acoustical Society 2021: Making Waves, AAS 2021, pp. 41-46.
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Breakout from ducts can be a major source of noise on industrial sites. The emitted noise is harmful at sufficient levels and must be reduced. Reducing noise levels using appropriate methods after the fact can be both costly and time consuming. This can be avoided by correctly predicting duct transmission loss before the duct is installed and choosing a suitable construction. In this paper the breakout from circular ducts will be presented as part of a parametric study. Parameters such as duct radius and wall thickness will be used to allow for a suitable choice of duct construction. In practical systems duct radii can be several metres in diameter and this is reflected by the range of the study. The breakout noise is calculated using a semi analytic finite element method. The first step in this method requires determination of the duct's modal properties which is calculated using a numerical eigenvalue analysis. The waves are then propagated along the duct using an analytic expression. A monopole sound source is used to excite the system, simulating the complex acoustic field within HVAC ducts with the transmission loss calculated from the difference between radially propagating sound power to axially propagating sound power.
Xiao, T, Qiu, X & Halkon, B 1970, 'Using a Laser Doppler Vibrometer to Estimate Sound Pressure in Air', Springer, The 18th Asia-Pacific Vibration Conference, Springer International Publishing, Sydney, pp. 371-377.
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Xu, M, Song, Y, Chen, Y, Huang, S & Hao, Q 1970, 'Invariant EKF based 2D Active SLAM with Exploration Task', 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021 IEEE International Conference on Robotics and Automation (ICRA), IEEE, Xi'an, China, pp. 5350-5356.
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Right invariant extended Kalman filter (RIEKF) based simultaneous localization and mapping (SLAM) proposed recently has shown to be able to produce more consistent SLAM estimates as compared with traditional EKF based SLAM methods, including some improved EKF SLAM methods such as observability constrained-EKF (OC-EKF) SLAM. Latest results have demonstrated that its performance is very close to optimization based SLAM algorithms such as iSAM. In this paper, we propose to use RIEKF SLAM algorithm in active SLAM where both the predicted SLAM results for choosing control actions and the actual estimated SLAM results applying the selected control actions are computed using RIEKF algorithms. The advantages over traditional EKF based active SLAM are the more accurate and consistent predicted uncertainty estimates which result in robustness of the active SLAM algorithm. The advantages over optimization based active SLAM is the reduced computational cost. Simulation results are presented to validate the advantages of the proposed algorithm3.
Yang, S, Yu, K, Lammers, T & Chen, F 1970, 'Artificial Intelligence in Pilot Training and Education – Towards a Machine Learning Aided Instructor Assistant for Flight Simulators', HCI International 2021 - Posters, International Conference on Human-Computer Interaction, Springer International Publishing, Virtual Event, pp. 581-587.
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The aviation industry was set to see unprecedented growth over the next two decades. Key occupations predicted to be in shortage included not only pilots, but also flight instructors. Undoubtedly, Covid-19 is currently having a huge impact on the industry. Nevertheless, the current environment further strengthens the need for pilots to maintain their training. Consequently, there is pressure to deliver high-quality training outcomes for an increasing number of pilots and trainees with limited resources available. Current simulator-based training schemes are limited by placing a significant reliance on the personal experience of flight instructors to assess pilot performance. Finding ways to increase the quality and efficiency of simulator-based training is therefore of high importance. With recent advances in artificial intelligence, it is possible to use machine learning techniques to extract latent patterns from massive datasets, to analyze pilot trainees’ activities, and to provide feedback on their performance by processing hundreds of different parameters available on flight simulators. An ML-aided pilot training and education framework is needed that exploits the power of the ML techniques for more objective performance evaluation. In this paper, we describe a conceptual framework for such a system and outline steps toward the development of a full digital instructor system with the potential to overcome current limitations and enabling comprehensive and meaningful feedback that is tailored to the individual need of the trainee.
Yoo, C, Heon Lee, JJ, Anstee, S & Fitch, R 1970, 'Path Planning in Uncertain Ocean Currents using Ensemble Forecasts', 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021 IEEE International Conference on Robotics and Automation (ICRA), IEEE, Xi'an, China, pp. 8323-8329.
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We present a path planning framework for marine robots subject to uncertain ocean currents that exploits data from ensemble forecasting, which is a technique for current prediction used in oceanography. Ensemble forecasts represent a distribution of predicted currents as a set of flow fields that are considered to be equally likely. We show that the typical approach of computing the vector-wise mean and variance over this set can yield meaningless results, and propose an alternative approach that considers each flow field in the ensemble simultaneously. Our framework finds a sequence of vehicle controls that minimises the root-mean-square error distance (RMSE) over the full set of ensemble-induced trajectories. The key to achieving computational efficiency in this approach is our use of Monte Carlo tree search (MCTS) with a specialised heuristic that improves convergence rate while preserving asymptotic optimality and the anytime property. We demonstrate our results using real ensemble forecasts provided by the Australian Bureau of Meteorology, and provide comparisons with the deterministic mean-based approach where we observe RMSE reductions of 92% and 43% in two example scenarios. Further, we argue that the framework can be used in a plan-as-you-go manner where ensemble forecasts change over time. These results help to introduce ensemble forecasts as a viable source of data to improve path planning in marine robotics.
Zhang, S, Zhao, L, Huang, S, Ma, R, Hu, B & Hao, Q 1970, '3D Reconstruction of Deformable Colon Structures based on Preoperative Model and Deep Neural Network', 2021 IEEE International Conference on Robotics and Automation (ICRA), 2021 IEEE International Conference on Robotics and Automation (ICRA), IEEE, Xi'an, China, pp. 11457-11462.
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In colonoscopy procedures, it is important to rebuild and visualize the colonic surface to minimize the missing regions and reinspect for abnormalities. Due to the fast camera motion and deformation of the colon in standard forward-viewing colonoscopies, traditional simultaneous localization and mapping (SLAM) systems work poorly for 3D reconstruction of colon surfaces and are prone to severe drift. Thus in this paper, a preoperative colon model segmented from CT scans is used together with the colonoscopic images to achieve the 3D colon reconstruction. The proposed framework includes dense depth estimation from monocular colonoscopic images using a deep neural network (DNN), visual odometry (VO) based camera motion estimation and an embedded deformation (ED) graph based non-rigid registration algorithm for deforming 3D scans to the segmented colon model. A realistic simulator is used to generate different simulation datasets with ground truth. Simulation results demonstrate the good performance of the proposed 3D colonic surface reconstruction method in terms of accuracy and robustness. In-vivo experiments are also conducted and the results show the practicality of the proposed framework for providing useful shape and texture information in colonoscopy applications.
Zhang, Z, Oberst, S & Lai, JCS 1970, 'Towards Overcoming the Challenges of the Prediction of Brake Squeal Propensity', Springer International Publishing, Switzerland, pp. 47-53.
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Despite significant efforts made in the last two decades for the
analysis and prediction of brake squeal propensity, brake squeal remains a major source of customer dissatisfaction and warranty-related costs. Brake squeal is a fugitive nonlinear self excitation phenomenon induced by friction. Traditional linear complex eigenvalue analysis (CEA) combined with noise dynamometer tests has achieved some success in the analysis of brake squeal and in designing countermeasures in suppressing brake squeal. However, prediction of brake squeal propensity without experimental testings is generally unreliable because of three main challenges. Firstly, most conventional analysis methods used are linear but brake squeal could be caused by nonlinearities. Secondly, while non-linear time-domain simulations have achieved some success, they require substantial high-performance computing resources and are too time consuming for practical applications. Thirdly, even if the second challenge can be overcome, there are many determining and interacting factors that are not known exactly such as material properties of pad and disc, operating conditions (brake pad pressure, temperature, speed), contact conditions between pad and
disc, non-linear boundary conditions and modelling of friction. In this paper,
examples are given to illustrate the success and limitations of the CEA. To address difficulties in predicting brakes squeal posed by nonlinearity, uncertain contact conditions and friction modelling, examples will be given to illustrate how a stochastic approach using the traditional linear eigenvalue analysis could be used to improve the prediction of brake squeal by identifying unstable vibration modes that are not too sensitive to these uncertainties.
Zhao, E, Walker, PD, Ong, A & Al-Widyan, F 1970, 'Measuring Road Conditions with an IMU and GPS Monitoring System', Springer International Publishing, pp. 95-101.
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Zhao, L, Mao, Z & Huang, S 1970, 'Feature-Based SLAM: Why Simultaneous Localisation and Mapping?', Robotics: Science and Systems XVII, Robotics: Science and Systems 2021, Robotics: Science and Systems Foundation, virtual.
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Zhao, S & Qiu, X 1970, 'An Experimental Study on Virtual Sound Barrier Performance in Workplaces', Vibration Engineering for a Sustainable Future: Active and Passive Noise and Vibration Control, Asia-Pacific Vibration Conference, Springer International Publishing, Australia, pp. 321-326.
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Virtual sound barrier (VSB) represents an array of loudspeakers and microphones forming an acoustic barrier to create a quiet zone without blocking light and air circulation. Although the concept of VSB has been proposed for many years, practical applications are still rare due to its performance and cost. This chapter explores two application scenarios of implementing VSB in workplaces: one is an eight-channel circular VSB system in a small room to create a quiet zone and the other is an eight-channel planar VSB system mounted to the door of the small room to prevent the outside noise from propagating inside. For the circular VSB system, the loudspeakers are uniformly placed along a circle with a diameter of 1.4 m to create a quiet zone with a diameter of 0.8 m. The experimental results show that the system is effective in reducing the low-frequency noise from 100 Hz to 250 Hz, and the noise reduction can reach 8 dB at 100 Hz. For the planar VSB system, the loudspeakers are placed at the door to reduce the noise propagating from the outside to inside. The experimental results show that the low-frequency noise below 250 Hz is effectively reduced by up to 6 dB at 80 Hz. These results demonstrate the feasibility of VSB for blocking low-frequency noise propagation, but further improvements are needed at higher frequencies above 400 Hz.
Zhao, S & Zhu, Q 1970, 'Comparative study of loudspeaker position optimization techniques for multizone sound field reproduction', INTER-NOISE and NOISE-CON Congress and Conference Proceedings, Institute of Noise Control Engineering (INCE), pp. 2486-2493.
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Mutlizone sound field reproduction aims to generate personal sound zones in a shared space with multiple loudspeakers. Conventionally, loudspeakers are placed to form a regular pattern such as circular, arc or linear array, which are empirical rather than optimal mainly for the convenience of physical placement. Recently, several algorithms have been proposed to select a fixed number of loudspeaker locations from a large set of candidate positions, such as the sparse regularization (i.e. Lasso and Elastic Net) methods, the Constrained Match Pursuit (CMP) method, the Gram-Schmidt Orthogonalization (GSO) method etc. Most of these methods were investigated for single-zone rather than mulit-zone sound field reproduction based on the pressure matching techniques. This paper compares the performance of the state-of-the-art techniques for loudspeaker position optimization in a multizone sound field reproduction system in terms of reproduction error, acoustic contrast and array effort. Simulation results demonstrate that the CMP-LS method shows the best performance in terms of lower MSE and higher AC while the Lasso method needs the lowest AE.
