Akbarzadeh, M, Oberst, S, Sepehrirahnama, S & Halkon, B 2023, 'Acoustic radiation force-induced push-pull particle oscillations', Journal of the Acoustical Society of America.
Aldini, S, Singh, AK, Leong, D, Wang, Y-K, Carmichael, MG, Liu, D & Lin, C-T 2023, 'Detection and Estimation of Cognitive Conflict During Physical Human–Robot Collaboration', IEEE Transactions on Cognitive and Developmental Systems, vol. 15, no. 2, pp. 959-968.
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Robots for physical Human-Robot Collaboration (pHRC) often need to adapt their admittance and how they operate due to several factors. As the admittance of the system becomes variable throughout the workspace, it is not always straightforward for the operator to predict the robot’s behaviour. Previous work demonstrated that cognitive conflicts can be detected during one-dimensional tasks. This work assesses whether cognitive conflicts can also be detected during 2D tasks in pHRC and a classification problem is formulated. Different robot admittance profiles anticipating the stimulus translated into different levels of cognitive conflict. Several commonly used classification algorithms for EEG signals were evaluated to classify different levels of cognitive conflict. Results demonstrate that cognitive conflict level is lower when the admittance smoothly decreases before unexpected events when compared to conditions in which the admittance abruptly decreases before the stimulus. Among the classification algorithms, Convolutional Neural Network has shown the best results to classify different levels of cognitive conflict. Results suggest the feasibility of adaptive approaches for future pHRC control systems that close the loop on users through EEG signals. The detected human cognitive state can also be used to assess and improve the predictability of Human-Robot teams in various pHRC applications.
Alfouneh, M, Hoang, V-N, Luo, Z & Luo, Q 2023, 'Topology optimization for multi-layer multi-material composite structures', Engineering Optimization, vol. 55, no. 5, pp. 773-790.
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This article investigates topology optimization of multi-layer multi-material composite structures under static loading. A moving iso-surface threshold optimization method, previously well defined for single or cellular materials, is extended to multi-layer multi-material structures using a physical response function discrepancy scheme. It is also integrated with an alternating active-phase algorithm as an alternative procedure. The proposed methods are applied to three types of objective functions, namely, minimizing compliance, maximizing mutual strain energy and minimizing full-stress designs. The corresponding response functions relevant to each optimization problem according to the proposed topology optimization methods are strain energy density, mutual strain energy density and von Mises stress, respectively. Examples are presented and compared with those available in the literature to verify the derived formulations on topology optimization for multi-layer multi-material structures. Highlights Optimization by integrating MIST with alternating active phase for multi-materials Extended MIST to topology optimization for multi-layer and multi-materials Multimaterial design to maximize mutual energy, minimize compliance and full stress.
Alsouda, F, Bennett, NS, Saha, SC, Salehi, F & Islam, MS 2023, 'Vapor Compression Cycle: A State-of-the-Art Review on Cycle Improvements, Water and Other Natural Refrigerants', Clean Technologies, vol. 5, no. 2, pp. 584-608.
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Air conditioning and refrigeration have become necessary in modern life, accounting for more than 7.8% of greenhouse gases (GHG) emitted globally. Reducing the environmental impact of these systems is crucial for meeting the global GHG emission targets. Two principal directions must be considered to reduce the environmental impact of air conditioning systems. Firstly, reducing the direct effect by looking at less harmful refrigerants and secondly, reducing the indirect effect by searching for options to improve the system efficiency. This study presents the latest developments in the vapor compression cycle and natural refrigerants, focusing on water as a refrigerant. Natural refrigerants, and especially water, could be the ultimate solution for the environmental problems associated with the operation of vapor compression cycle (VCC) cooling systems, including ozone depletion (OD) and global warming (GW). Reducing the environmental impact of building cooling systems is essential, and the recent system improvements made to enhance the system coefficient of performance (COP) are thoroughly discussed in this paper. Though the cycle improvements discussed in this work are essential and could increase the system efficiency, they still need to solve the direct environmental impact of refrigerants. Accordingly, this paper suggests that natural refrigerants, including water, are the most suitable strategic choice to replace the current refrigerants in the refrigeration and air conditioning industry. Finally, this study reviews the latest VCC system improvements and natural refrigerants in order to guide interested researchers with solutions that may reduce the environmental impact of VCC systems and suggest future research areas.
Bala, D, Hossain, MS, Hossain, MA, Abdullah, MI, Rahman, MM, Manavalan, B, Gu, N, Islam, MS & Huang, Z 2023, 'MonkeyNet: A robust deep convolutional neural network for monkeypox disease detection and classification', Neural Networks, vol. 161, pp. 757-775.
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The monkeypox virus poses a new pandemic threat while we are still recovering from COVID-19. Despite the fact that monkeypox is not as lethal and contagious as COVID-19, new patient cases are recorded every day. If preparations are not made, a global pandemic is likely. Deep learning (DL) techniques are now showing promise in medical imaging for figuring out what diseases a person has. The monkeypox virus-infected human skin and the region of the skin can be used to diagnose the monkeypox early because an image has been used to learn more about the disease. But there is still no reliable Monkeypox database that is available to the public that can be used to train and test DL models. As a result, it is essential to collect images of monkeypox patients. The 'MSID' dataset, short form of 'Monkeypox Skin Images Dataset', which was developed for this research, is free to use and can be downloaded from the Mendeley Data database by anyone who wants to use it. DL models can be built and used with more confidence using the images in this dataset. These images come from a variety of open-source and online sources and can be used for research purposes without any restrictions. Furthermore, we proposed and evaluated a modified DenseNet-201 deep learning-based CNN model named MonkeyNet. Using the original and augmented datasets, this study suggested a deep convolutional neural network that was able to correctly identify monkeypox disease with an accuracy of 93.19% and 98.91% respectively. This implementation also shows the Grad-CAM which indicates the level of the model's effectiveness and identifies the infected regions in each class image, which will help the clinicians. The proposed model will also help doctors make accurate early diagnoses of monkeypox disease and protect against the spread of the disease.
Begum, Z, Saleem, M, Islam, SU & Saha, SC 2023, 'Numerical Study of Natural Convection Flow in Rectangular Cavity with Viscous Dissipation and Internal Heat Generation for Different Aspect Ratios', Energies, vol. 16, no. 14, pp. 5267-5267.
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Numerical simulations have been performed to investigate the influence of constant volumetric heat generation and viscous dissipation on the unsteady natural convection flow of an incompressible Newtonian fluid contained in a rectangular cavity. The left vertical wall of the cavity is cooled, while the right vertical wall is heated, and the bottom and top walls are adiabatic. A numerical technique based on the implicit finite difference method (IFDM), along with an upwind finite difference scheme and an iterative successive over relaxation (SOR) technique, is employed to solve the governing equations numerically. The effect of physical parameters, namely the modified Rayleigh number (103≤Ra≤107), aspect ratio (1≤A≤4), Prandtl number (Pr=0.7, 1.0, 6.2, 15), volumetric internal heat generation parameter (Qλ=0, 1), and Eckert number (0≤Ec≤10−6), on the streamlines and isotherms are discussed graphically. Variations of maximum stream function, as well as average and local Nusselt number, are also discussed. The results show that the increase in Eckert number from 0 to 10−4 causes the average heat transfer to decrease, while Pr=0.71, Ra=104, and Qλ=0. Additionally, the average heat transfer decreases as the cavity width increases from 1 to 4, while Pr=0.71, Ra = 5×104, Ec=10−6 and Qλ=1. The results of the numerical model used here are in excellent accord with earlier findings.
Blamires, S, Lozano-Picazo, P, Bruno, AL, Arnedo, M, Ruiz-León, Y, González-Nieto, D, Rojo, FJ, Elices, M, Guinea, GV & Pérez-Rigueiro, J 2023, 'The Spider Silk Standardization Initiative (S3I): A powerful tool to harness biological variability and to systematize the characterization of major ampullate silk fibers spun by spiders from suburban Sydney, Australia', Journal of the Mechanical Behavior of Biomedical Materials, vol. 140, pp. 105729-105729.
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Büscher, J, Paranjape, A, Möhle, R, Polikarpov, M, Plettenberg, N, Zwinkau, R, Deuse, J & Schmitt, RH 2023, 'Bauteile ressourceneffizient reinigen mithilfe von KI', JOT Journal für Oberflächentechnik, vol. 63, no. 1, pp. 40-43.
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Cao, C, Nogueira, L, Zhu, H, Keller, J, Best, G, Garg, R, Kohanbash, D, Maier, J, Zhao, S, Yang, F, Cujic, K, Darnley, R, DeBortoli, R, Drozd, B, Sun, P, Higgins, I, Willits, S, Armstrong, G, Zhang, J, Hollinger, G, Travers, M & Scherer, S 2023, 'Exploring the Most Sectors at the DARPA Subterranean Challenge Finals', Field Robotics, vol. 3, no. 1, pp. 801-836.
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Autonomous robot navigation in austere environments is critical to missions like “search and rescue”, yet it remains difficult to achieve. The recent DARPA Subterranean Challenge (SubT) highlights prominent challenges including GPS-denied navigation through rough terrains, rapid exploration in large-scale three-dimensional (3D) space, and interrobot coordination over unreliable communication. Solving these challenges requires both mechanical resilience and algorithmic intelligence. Here, we present our approach that leverages a fleet of custom-built heterogeneous robots and an autonomy stack for robust navigation in challenging environments. Our approach has demonstrated superior navigation performance in the SubT Final Event, resulting in the fastest traversal and most thorough exploration of the environment, which won the “Most Sectors Explored Award.” This paper details our approach from two aspects: mechanical designs of a marsupial ground-and-aerial system to overcome mobility challenges and autonomy algorithms enabling collective rapid exploration. We also provide lessons learned in the design, development, and deployment of complex but resilient robotic systems to overcome real-world navigation challenges.
Cullen, M, Ji, JC & Parnell, J 2023, 'Real time GMAW weld bead profile mapping using acoustic sensing', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A284-A284.
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Monitoring the penetration profile of Gas Metal Arc Welding (GMAW) is critical in determining the overall quality and structural integrity of the produced weld bead. However, due to the instability and complexity of the GMAW process, it can be difficult to accurately monitor the weld bead formation and penetration profile. Due to this complexity, traditional methods for modeling the welding process, such as CFD analysis, are unable to be computed in real time. In this work, a new analytical method of estimating the weld bead penetration profile in real time using the sound signal is proposed. This method monitors the sound signal generated during the droplet transfer process to estimate both the heat input and material deposition into the weld pool. Using this estimation, a digital twin of the welding process is produced, allowing for the operator to monitor the weld bead formation in real time, guaranteeing the structural integrity of the final weld bead.
Curtis, K, Brown, J, Sharwood, LN, Risi, D, Eager, D, Holland, AJA, Beck, B, Erskine, C, Lockhart, K, Cooke, K, Adams, S, Teague, WJ & Mitchell, R 2023, 'Playground injury prevention: the need for consistent and national implementation of Australian safety standards', Australian and New Zealand Journal of Public Health, vol. 47, no. 2, pp. 100023-100023.
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OBJECTIVES: Hospitalisation rates for injury, including at playgrounds, have not changed in the past decade. There are nine Australian Standards specific to playgrounds. The impact (if any) of these standards on playground injury resulting in hospitalisation is unknown. METHODS: Retrospective data for patients under 18 years presenting to emergency departments and/or admitted between October 2015 and December 2019 due to an injury documented as occurring at a playground were retrieved by the Illawarra Shoalhaven Local Health District Planning, Information and Performance Department. Maintenance and Australian Standard (AS) compliance data for the 401 local playgrounds were requested from the four Local Governments in Illawarra Shoalhaven Local Health District. Descriptive statistics were used. RESULTS: A total of 548 children were treated in emergency departments and/or admitted following playground injury. There was an overall increase of 39.3% in playground injury across the study period, and expenditure rose from $43,478 in 2011 to $367,259 in 2019 (a 744.7% increase). CONCLUSIONS: Playground injury has not decreased in the Illawarra Shoalhaven. Data regarding maintenance and AS compliance are lacking. This is not unique to our region. IMPLICATIONS FOR PUBLIC HEALTH: Without a national approach to adequately resource and monitor playground injury, it is not possible to assess the impact of Australian Standards or any injury prevention program.
Darroch, MM, Cooper-Woolley, B & Halkon, BJ 2023, 'Design and development of SiteHive MEMS based system for real-time vibration monitoring', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A303-A303.
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Construction projects need to proactively manage their works that may cause vibration impacts to nearby structures and stakeholders. Risks of vibration include cosmetic and structural damage to buildings and threats to human comfort. The advent of MEMS accelerometers offers significant opportunities to improve on traditional vibration monitoring practices based on geophones. Geophones measure velocity which preclude acceleration based measurements and calculations like vibration dose value (the measure for human comfort), groundborne noise, and auto-levelling. The inability to capture these results means additional monitoring devices are required to capture all key measurements. MEMS-based vibration monitoring systems can be much cheaper, smaller, and more power efficient than traditional vibration monitoring systems. This enables easier installation, greater mobility, and more monitoring to be conducted. SiteHive has worked extensively with the National Measurement Institute (NMI) and the University of Technology Sydney (UTS) to test and validate the efficacy of the MEMS-based accelerometers and develop a calibration system for MEMS-based devices. This paper will outline the design research and findings that have gone into this development, results from field testing, and details on the value offered by this innovation.
Das, S, Bhattacharjee, M, Thiyagarajan, K & Kodagoda, S 2023, 'Conformable packaging of a soft pressure sensor for tactile perception', Flexible and Printed Electronics, vol. 8, no. 3, pp. 035006-035006.
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Abstract Humans can perceive surface properties of an unfamiliar object without relying solely on vision. One way to achieve it is by physically touching the object. This human-inspired tactile perception is a complementary skill for robotic tactile perception. Robot perception depends on the informational quality of the tactile sensor; thus, packaging sensors and integrating them with robots plays a crucial role. In this work, we investigate the influence of conformable packaging designs on soft polydimethylsiloxane-based flexible pressure sensors that work in a variety of surface conditions and load levels. Four different 3D printed packaging designs capable of maintaining sensor trends have been developed. The low detection limits of 0.7 kPa and 0.1 kPa in the piezoresistive and piezocapacitive sensors, respectively, remain unaffected, and a performance variation as low as 30% is observed. Coefficient of variation and sensitivity studies have also been performed. Limit tests show that the designs can handle large forces ranging from 500 N to more than a 1000 N. Lastly, a qualitative study was performed, which covered prospective use-case scenarios as well as the advantages and downsides of each sensor casing design. Overall, the findings indicate that each sensor casing is distinct and best suited for tactile perception when interacting with objects, depending on surface properties.
Das, S, Bhattacharjee, M, Thiyagarajan, K & Kodagoda, S 2023, 'Nonlinear Response Analysis of a Polymer-Based Piezoresistive Flexible Tactile Sensor at Low Pressure', IEEE Sensors Letters, vol. 7, no. 11, pp. 1-4.
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Farooq, U, Riaz, HH, Munir, A, Zhao, M, Tariq, A & Islam, MS 2023, 'Application of heliox for optimized drug delivery through respiratory tract', Physics of Fluids, vol. 35, no. 10.
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Understanding the transportation and deposition (TD) of inhaled particles in the upper respiratory tract is crucial for predicting health risks and treating pulmonary diseases. The available literature reports highly turbulent flow in the extrathoracic (ET) region during normal breathing, which leads to higher deposition of the drug aerosol in this region. To improve the targeted deposition of inhaled drugs, in the tracheobronchial airways, it is essential to understand the flow and particle transport dynamics and reduce the turbulence behavior at the ET region. The less-dense heliox gas could reduce the turbulence behavior at the ET; however, the knowledge of heliox inhalation therapies in drug aerosol TD remains underachieved to realize the full potential for assisted breathing and drug delivery. Additionally, the impact of the inhalation of heliox mixed with other gases on particle deposition is missing in the literature. Therefore, this study aims to develop a mixture model to advance the knowledge of inhalation therapy. A heliox (78% helium and 22% oxygen) and a mixture of heliox and air are used to understand the flow behavior and particle TD in airways. The impact of different inhalation and Stokes numbers on the deposition efficiencies in the ideal and age-specific upper airways is studied. The study reports that less-dense heliox gas has lower turbulence intensity and results in lower deposition efficiency in the G3–G5 lung airways compared to air and mixture inhalations. Moreover, slightly higher deposition efficiencies during mixture inhalation as compared to air inhalation are found in the upper airways. The deposition patterns of different inhalations obtained in this study could help improve targeted drug delivery into the upper and deeper lung airways.
Feng, K, Ji, JC & Ni, Q 2023, 'A novel gear fatigue monitoring indicator and its application to remaining useful life prediction for spur gear in intelligent manufacturing systems', International Journal of Fatigue, vol. 168, pp. 107459-107459.
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With the material degradation of gear over its service lifespan, the gearbox is prone to fatigue, especially under harsh working environments. The interaction between gear fatigue and gear dynamics often results in high complexity measurements. This poses significant challenges to developing effective vibration-based techniques to monitor the gear fatigue propagation and predict its remaining useful life (RUL). To address this issue, a novel transmission error-based indicator is proposed to assess the fatigue severity, and then it is utilized to predict the RUL of the gearbox. The effectiveness of the proposed prognostic methodology is validated using endurance tests.
Feng, K, Ji, JC, Ni, Q & Beer, M 2023, 'A review of vibration-based gear wear monitoring and prediction techniques', Mechanical Systems and Signal Processing, vol. 182, pp. 109605-109605.
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Gearbox plays a vital role in a wide range of mechanical power transmission systems in many industrial applications, including wind turbines, vehicles, mining and material handling equipment, oil and gas processing equipment, offshore vessels, and aircraft. As an inevitable phenomenon during gear service life, gear wear affects the durability of gear tooth and reduces the remaining useful life of the gear transmission system. The propagation of gear wear can lead to severe gear failures such as gear root crack, tooth spall, and tooth breakage, which can further cause unexpected equipment shutdown or hazardous incidents. Therefore, it is necessary to monitor gear wear propagation progression in order to perform predictive maintenance. Vibration analysis is a widely used and effective technique to monitor the operating condition of rotating machinery, especially for the diagnosis of localized failures such as gear root crack and tooth surface spalling. However, vibration-based techniques for gear wear analysis and monitoring are very limited, mainly due to the difficulties in identifying the complex vibration characteristics induced by gear wear propagation. Understanding the effect of gear wear on vibration characteristics is essential to develop vibration-based techniques for monitoring and tracking gear wear evolution. However, no research work has been previously published to summarize the research progress in vibration-based gear wear monitoring and prediction. To fill the research gap, this review paper aims to conduct a state-of-the-art comprehensive review on vibration-based gear wear monitoring, including studying the gear surface features caused by different gear wear mechanisms, investigating the relationships between gear surface features and vibration characteristics, and summarizing the current research progress of vibration-based gear wear monitoring. This review also makes some recommendations for future research work in this area. It is e...
Feng, K, Ji, JC, Ni, Q, Li, Y, Mao, W & Liu, L 2023, 'A novel vibration-based prognostic scheme for gear health management in surface wear progression of the intelligent manufacturing system', Wear, vol. 522, pp. 204697-204697.
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Gearbox has a compact structure, a stable transmission capability, and high transmission efficiency. Thus, it is widely applied and used as a critical transmission system in intelligent manufacturing systems, such as machine tools and robotics. The gearbox usually operates in harsh and non-stationary working environments, making the gear surface prone to wear. The progression of gear surface wear may lead to severe gear failures, such as gear tooth breakage and root crack, potentially damaging the whole gear transmission system. Therefore, it is essential to assess the gear surface wear progression and predict its remaining useful life (RUL) in order to ensure the reliable operation of the gear transmission system. To this end, this paper developed a novel gear wear prognostic scheme based on vibration analysis for gear health management. More specifically, a novel health indicator (HI) is first developed for gear wear monitoring in the proposed prognostic scheme. The novel HI, inferred from the cyclic correntropy and Wasserstein distance (WD), can accurately reflect the wear-induced cyclic correntropy spectra distribution change over time. Therefore, the novel HI can robustly evaluate the gear wear severity with high accuracy. With the developed HI, a network, namely the optimized gated recurrent unit (GRU), is applied for predicting the gear transmission system RUL during surface wear progression. As for the optimized GRU network, the genetic algorithm (GA) is applied to find the optimal hyperparameters adaptively, which can significantly improve the practicality of the developed prognostic scheme. To conclude, the developed prognostic scheme can effectively reveal the gear wear propagation characteristics and predict the RUL accurately. A series of endurance tests are conducted to verify the effectiveness of the developed prognostic scheme for gear health management in surface wear progression.
Feng, K, Ji, JC, Ni, Q, Yun, H, Zheng, J & Liu, Z 2023, 'A novel vibration indicator to monitor gear natural fatigue pitting propagation', Structural Health Monitoring, vol. 22, no. 5, pp. 3126-3140.
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Fatigue pitting can reduce the gear surface durability and induce other severe failures, which will eventually lead to the complete loss of transmission function of the transmission system. Thus, monitoring fatigue pitting progression is vital to avoid unexpected economic losses and incidents. Thanks to the unique characteristics of the gear meshing process, there is a close relationship between the tribological features of fatigue pitting and gear vibration cyclostationarity. Based on the vibration cyclostationarity, this paper develops a novel second-order cyclostationary (CS2) fatigue pitting monitoring indicator, which can accurately assess the degradation status of the gear system and benefit subsequent health management. The advantage of the developed cyclostationary indicator in evaluating and monitoring the process of fatigue pitting propagation is demonstrated with the natural fatigue pitting progression test, through comparisons with other conventional indicators.
Feng, K, Ni, Q, Chen, Y, Ge, J & Liu, Z 2023, 'A cyclostationarity-based wear monitoring framework of spur gears in intelligent manufacturing systems', Structural Health Monitoring, vol. 22, no. 5, pp. 3092-3108.
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The gearbox is widely applied as the mechanical transmission system of intelligent manufacturing systems, such as machine tools and robotics. The harsh working environments make the gear surface prone to wear. The progression of surface wear can bring severe failures to the gear tooth, including gear tooth root crack, surface spalling of gear tooth, and tooth breaking, all of which could damage the whole transmission system. Hence, it is essential to monitor and evaluate the gear surface wear propagation. The gear wear has been proven highly relevant with the vibration second-order cyclostationary (CS2) characteristics. Therefore, this paper develops a novel cyclostationarity-based framework to monitor and evaluate gear wear propagation. More specifically, the squared envelope (SE) of the residual signal, removing deterministic components, is utilized to identify the gear wear distribution and its propagation trends, validated using the measured gear surface morphology. Moreover, a new CS2-based indicator is proposed to assess the severity of gear surface wear, achieving a high correlation with measured surface roughness: [Formula: see text] is more than 0.9. The developed cyclostationarity-based framework can comprehensively evaluate the degradation status of the gear system caused by surface wear, significantly benefiting the health management of the gear transmission system, which is of great practical value for the health management of intelligent manufacturing systems. A series of endurance tests are conducted to verify the effectiveness and superiority of the developed framework for gear wear monitoring compared with the conventional indicators.
Feng, K, Xu, Y, Wang, Y, Li, S, Jiang, Q, Sun, B, Zheng, J & Ni, Q 2023, 'Digital Twin Enabled Domain Adversarial Graph Networks for Bearing Fault Diagnosis', IEEE Transactions on Industrial Cyber-Physical Systems, vol. 1, pp. 113-122.
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Feng, Y, Wang, Q, Yu, Y, Zhang, T, Wu, D, Chen, X, Luo, Z & Gao, W 2023, 'Experimental-numerical-virtual (ENV) modelling technique for composite structure against low velocity impacts', Engineering Structures, vol. 278, pp. 115488-115488.
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Ghalambaz, M, Mehryan, SAM, Ramezani, SR, Hajjar, A, El Kadri, M, Islam, MS, Younis, O & Ghodrat, M 2023, 'Phase change heat transfer in a vertical metal foam-phase change material thermal energy storage heat dissipator', Journal of Energy Storage, vol. 66, pp. 107370-107370.
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Guertler, M, Tomidei, L, Sick, N, Carmichael, M, Paul, G, Wambsganss, A, Hernandez Moreno, V & Hussain, S 2023, 'WHEN IS A ROBOT A COBOT? MOVING BEYOND MANUFACTURING AND ARM-BASED COBOT MANIPULATORS', Proceedings of the Design Society, vol. 3, pp. 3889-3898.
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AbstractCollaborative robots (“cobots”) have attracted growing attention in academia and industry over the last years. Due to in-built safety features and easy programming, they allow for close human-cobot collaboration and support e.g. flexible manufacturing. However, the lack of a common understanding what a cobot is along with its traditional focus on arm-based cobots complicates further research and industry adoption. Thus, this paper analyses the variety of definitions in literature incl. standards and practice examples to derive a consistent and holistic definition and taxonomy of what a collaborative robot is. Aside from contributing a structured overview of various forms of human-robot collaboration, this builds an important foundation for future research as it systematically differentiates different cobot types. Companies and other organisations will benefit by a better understanding of what type of cobot they need and how to ensure safe collaboration.
Guertler, MR, Brackemann, T, Burden, A & Caldwell, G 2023, 'Mapping socio-technical dependencies to enable the successful adoption of collaborative robots in industry', Procedia CIRP, vol. 119, pp. 564-569.
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Guo, Z, Zhao, S, Halkon, BJ & Clemon, L 2023, 'Simulation of active vibration control of a moving stage', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A164-A164.
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Active vibration control (AVC) has gained considerable interest due to its inherent adaptability and cost-effectiveness, with its ability to suppress vibrations in the controlled system across various applications. Existing studies focus on the AVC of non-moving systems and usually assume that the vibration signal to be controlled is known and can serve as the ideal reference signal in feedforward control systems. However, in many practical applications, the ideal reference signal is not accessible, and a sensor must be used to detect the reference signal. This can degrade the AVC performance, especially for a moving system. This study, therefore, aims to explore the potential application of piezoelectric stack actuators (PSA) to control the vibration of a moving stage driven by a stepper motor. The secondary path was estimated offline, and vibration data were collected at different moving speeds. The effects of the location of the reference sensor were initially investigated. Then, extensive simulations were conducted to evaluate the performance of different adaptive control algorithms regarding vibration reduction, convergence speed, computational complexities, etc. This research underlines the potential of integrating PSA within a moving system to effectively control its vibration.
Halkon, BJ, Darwish, A, Rothberg, S, Mohammadi, M & Oberst, S 2023, 'Correction of scanning laser Doppler vibrometer measurements when subjected to six degree-of-freedom base motion', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A74-A74.
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Scanning laser Doppler vibrometer (SLDV) measurements are affected by sensor head vibrations as though they are vibrations of the target surface itself. Previous work has established a fully general theoretical analysis which shows that the only measurement required for measurement correction is of the vibration velocity at the incident point on the final steering mirror in the direction of the outgoing laser beam. Two practical—but not quite perfect—options for measurement correction were presented (one more suitable to manufacturer implementation, one more applicable to the vibration engineer end user). In both cases, placement of the correction transducer is critical with correction working for totally arbitrary instrument vibration and scan angle. Experimental validation, employing frequency-domain based processing, has been completed for one degree-of-freedom, on-axis vibration. Simultaneously, advancements in the data processing approach have realised improved correction in practice, especially for lower frequencies and for transient, as opposed to statistically stationary, vibration. In this paper, extension of the experimental validation to six degree-of-freedom instrument vibration is presented for the first time. In combination with the latest data processing approaches, reductions in the measurement error of 29.4 and 28.2 dB for the frequency- and time-domain processing techniques, respectively, are realised.
Hertrampf, T, Oberst, S & Sepehrirahnama, S 2023, 'Recurrence rate spectrograms for impact localization in wood', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A142-A142.
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Characteristics like cellular grain structure, inhomogeneous density, aging, and altering environmental conditions (moisture, temperature) give wood highly anisotropic viscoelastic properties and non-linear vibrational wave propagation properties. Nonlinearity limits the use of linear methods, such as modal analysis and parameter identification via transfer functions. Acoustic localization of natural damage to wood, like crack growth, is of general interest in structural health monitoring of timber structures. Time-difference of arrival or energy attenuation is commonly used for localization, which are prone to boundary reflections or require the frequency response function. Recent advancements in machine learning-based classification of non-linear signals can achieve a much higher accuracy when recurrence rate-based spectrograms are used compared relative to conventional short-time Fourier transforms, especially in the presence of noise. Hence, in this work, multi-sensor measurements of impulse induced vibration in wood beams are classified by their distance to the excitation, based on their time series, avoiding a priori knowledge of a transfer function for the localization. The machine learning model is trained across various widths and thicknesses of samples, giving a localization estimate independent of beam dimensions. This research will contribute to early detection of damage in the field of vibration-based structural health monitoring of wood.
Hossain, A, Molla, MM, Kamrujjaman, M, Mohebujjaman, M & Saha, SC 2023, 'MHD Mixed Convection of Non-Newtonian Bingham Nanofluid in a Wavy Enclosure with Temperature-Dependent Thermophysical Properties: A Sensitivity Analysis by Response Surface Methodology', Energies, vol. 16, no. 11, pp. 4408-4408.
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The numerical investigation of magneto-hydrodynamic (MHD) mixed convection flow and entropy formation of non-Newtonian Bingham fluid in a lid-driven wavy square cavity filled with nanofluid was investigated by the finite volume method (FVM). The numerical data-based temperature and nanoparticle size-dependent correlations for the Al2O3-water nanofluids are used here. The physical model is a two-dimensional wavy square cavity with thermally adiabatic horizontal boundaries, while the right and left vertical walls maintain a temperature of TC and TH, respectively. The top wall has a steady speed of u=u0. Pertinent non-dimensional parameters such as Reynolds number (Re=10,100,200,400), Hartmann number (Ha=0,10,20), Bingham number (Bn=0,2,5,10,50,100,200), nanoparticle volume fraction (ϕ=0,0.02,0.04), and Prandtl number (Pr=6.2) have been simulated numerically. The Richardson number Ri is calculated by combining the values of Re with a fixed value of Gr, which is the governing factor for the mixed convective flow. Using the Response Surface Methodology (RSM) method, the correlation equations are obtained using the input parameters for the average Nusselt number (Nu¯), total entropy generation (Es)t, and Bejan number (Beavg). The interactive effects of the pertinent parameters on the heat transfer rate are presented by plotting the response surfaces and the contours obtained from the RSM. The sensitivity of the output response to the input parameters is also tested. According to the findings, the mean Nusselt numbers (Nu¯) drop when Ha and Bn are increased and grow when Re and ϕ are augmented. It is found that (Es)t is reduced by raising Ha, but (Es)t rises with the augmentation of ϕ and Re. It is also found that the ϕ and Re numbers have a positive sensitivity to the Nu¯, while the sensitivity of the Ha and Bn numbers is negative.
Hosseini, SAH, Rahmani, O, Hayati, H & Keshtkar, M 2023, 'An exact solution of dynamic response of DNS with a medium viscoelastic layer by moving load', Advances in Materials Research (South Korea), vol. 12, no. 3, pp. 193-210.
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This paper aims to analyze the dynamic response of a double nanobeam system with a medium viscoelastic layer under a moving load. The governing equations are based on the Eringen nonlocal theory. A thin viscoelastic layer has coupled two nanobeams together. An exact solution is derived for each nanobeam, and the dynamic deflection is achieved. The effect of parameters such as nonlocal parameter, velocity of moving load, spring coefficient and the viscoelastic layer damping ratio was studied. The results showed that the effect of the nonlocal parameter is significantly important and the classical theories are not suitable for nano and microstructures.
Ikram, MM, Saha, G & Saha, SC 2023, 'Unsteady conjugate heat transfer characteristics in hexagonal cavity equipped with a multi-blade dynamic modulator', International Journal of Heat and Mass Transfer, vol. 200, pp. 123527-123527.
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Purpose: The transient analysis of the thermal response and frictional loss characteristics for flow-modulated conjugate heat transfer phenomena has been investigated in the present study. The flow domain is a partitioned cavity of a hexagonal structure equipped with a multi-blade flow modulator. The clockwise rotating blade is adiabatic and stirrers the internal flow along with the natural convection caused by the bottom heated floor of uniform heat flux. The conjugate behavior is introduced through the solid subdomains consisting of two brick-made partitions and one glass partition of uniform thickness. The material of the partition wall reflects the physical aspects of industrial applications. Approach: The two-dimensional unsteady continuity, momentum, and energy equations are expressed in a non-dimensional form where the buoyant force is modeled through the Boussinesq approximation. The Arbitrary Lagrangian Euler (ALE) finite element is adopted to solve the moving mesh problem by formulating a free triangular discretization scheme. Parametric computational investigations are carried out for air as the working fluid (Pr = 0.71) and 3 different configurations of the rotating modulator while varying the other parameters, i.e., Reynolds number (Re) and Rayleigh number (Ra) for a fixed Biot number (Bi = 104). This dynamic mesh problem encompasses a wide range of parameters, i.e., (100 ≤ Re ≤ 103), and (104 ≤ Ra ≤ 106) for Bi = 104 to evaluate the thermodynamic response of the present thermo-fluid system. Various thermo-fluid system responses are visualized through the spatially average Nusselt number evaluated on the heated surface, system effectiveness, average thermal storage capacity, and frictional power loss of the flow domain. The thermal response is fragmented into individual responses in terms of component signal frequency by the Fast Fourier Transform (FFT) analysis. Findings: According to the current analysis, increasing the number of blades i...
Islam, MS, Rahman, MM, Larpruenrudee, P, Arsalanloo, A, Beni, HM, Islam, MA, Gu, Y & Sauret, E 2023, 'How microplastics are transported and deposited in realistic upper airways?', Physics of Fluids, vol. 35, no. 6.
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Microplastics are tiny plastic debris in the environment from industrial processes, various consumer items, and the breakdown of industrial waste. Recently, microplastics have been found for the first time in the airways, which increases the concern about long-term exposure and corresponding impacts on respiratory health. To date, a precise understanding of the microplastic transport to the airways is missing in the literature. Therefore, this first-ever study aims to analyze the microplastic transport and deposition within the upper lung airways. A computational fluid dynamics-discrete phase model approach is used to analyze the fluid flow and microplastic transport in airways. The sphericity concept and shape factor values are used to define the non-spherical microplastics. An accurate mesh test is performed for the computational mesh. The numerical results report that the highly asymmetric and complex morphology of the upper airway influences the flow fields and microplastic motion along with the flow rate and microplastic shape. The nasal cavity, mouth-throat, and trachea have high pressure, while a high flow velocity is observed at the area after passing the trachea. The flow rates, shape, and size of microplastics influence the overall deposition pattern. A higher flow rate leads to a lower deposition efficiency for all microplastic shapes. The nasal cavity has a high deposition rate compared to other regions. The microplastic deposition hot spot is calculated for shape and size-specific microplastic at various flow conditions. The findings of this study and more case-specific analysis will improve the knowledge of microplastic transport in airways and benefit future therapeutics development. The future study will be focused on the effect of various microplastic shapes on the human lung airways under the healthy and diseased airways conditions.
Jansing, S, Brockmann, B, Möhle, R, Patzelt, D & Deuse, J 2023, 'Potenziale von Motion Capturing bei der Erstellung von Ausführungsanalysen', Zeitschrift für wirtschaftlichen Fabrikbetrieb, vol. 118, no. 1-2, pp. 74-78.
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Abstract Neben der zeitökonomischen Gestaltung gewinnt die ergonomische Optimierung von Arbeitssystemen zunehmend an Bedeutung. Hohe Personalaufwände zur Erstellung bewegungsökonomischer Analysen sind jedoch Hemmnisse in deren industriellen Umsetzung. Markerloses Motion Capturing bietet Potenzial zur aufwandsreduzierten Erstellung entsprechender Analysen auf Basis des Prozessbausteinsystems MTM-Human Work Design. Der Beitrag beschreibt, wie Maschinelles Lernen unter Nutzung abstrahierter Videodaten zur Bewegungsanalyse eingesetzt werden kann.
Kalhori, H, Rafiee, R, Ye, L, Halkon, B & Bahmanpour, M 2023, 'Randomized Kaczmarz and Landweber algorithms for impact force identification on a composite panel', International Journal of Impact Engineering, vol. 176, pp. 104576-104576.
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Kha, J, Karimi, M & Maxit, L 2023, 'Acoustic radiation from a baffled finite shell in an underwater waveguide', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A55-A55.
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Analytical modelling of vibroacoustic systems can help us to understand the physical phenomena involved in more complex problems, and it provides a benchmark solution and reference upon which more complex systems can be built. In the present work, the system of interest consists of a finite elastic cylindrical shell inserted in infinitely rigid cylindrical baffles and immersed in an underwater acoustic waveguide. The latter consists of a finite fluid layer bounded by an upper free surface and a lower rigid floor. In such a fluid domain, the acoustic waves radiated from the excited shell will exhibit reflections off the boundaries. This phenomenon is modelled by the image-source theory and embedded in the fluid loading term, which intervenes in the shell equations. Investigations into the influence on the finiteness of the elastic shell, types of supports (i.e., simply supported, clamped, free, and combinations of these), and depth of the waveguide on the shell’s acoustic radiation are presented.
Kha, J, Karimi, M, Maxit, L, Skvortsov, A & Kirby, R 2023, 'Forced vibroacoustic response of a cylindrical shell in an underwater acoustic waveguide', Ocean Engineering, vol. 273, pp. 113899-113899.
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Kronowetter, F, Pretsch, L, Chiang, YK, Melnikov, A, Sepehrirahnama, S, Oberst, S, Powell, DA & Marburg, S 2023, 'Sound attenuation enhancement of acoustic meta-atoms via coupling', The Journal of the Acoustical Society of America, vol. 154, no. 2, pp. 842-851.
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Arrangements of acoustic meta-atoms, better known as acoustic metamaterials, are commonly applied in acoustic cloaking, for the attenuation of acoustic fields or for acoustic focusing. A precise design of single meta-atoms is required for these purposes. Understanding the details of their interaction allows improvement of the collective performance of the meta-atoms as a system, for example, in sound attenuation. Destructive interference of their scattered fields, for example, can be mitigated by adjusting the coupling or tuning of individual meta-atoms. Comprehensive numerical studies of various configurations of a resonator pair show that the coupling can lead to degenerate modes at periodic distances between the resonators. We show how the resonators' separation and relative orientation influence the coupling and thereby tunes the sound attenuation. The simulation results are supported by experiments using a two-dimensional parallel-plate waveguide. It is shown that coupling parameters like distance, orientation, detuning, and radiation loss provide additional degrees of freedom for efficient acoustic meta-atom tuning to achieve unprecedented interactions with excellent sound attenuation properties.
Larpruenrudee, P, Bennett, NS, Luo, Z, Fitch, R, Sauret, E & Islam, MS 2023, 'A novel design for faster hydrogen storage: A combined semi-cylindrical and central return tube heat exchanger', Journal of Energy Storage, vol. 71, pp. 108018-108018.
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Larpruenrudee, P, Do, DK, Bennett, NS, Saha, SC, Ghalambaz, M & Islam, MS 2023, 'Computational Fluid Dynamics Analysis of Spray Cooling in Australia', Energies, vol. 16, no. 14, pp. 5317-5317.
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Spray cooling technology offers high levels of uniform heat removal with very low fluid volumes and has found recent application in relatively small-scale use cases. Since it is a complex process, research can enable spray cooling to be applied more widely and at larger scales, such as in HVAC, as a means to operate more efficiently. Weather conditions are one of the main parameters that directly affect the effectiveness of spray cooling. This study investigates the spray cooling performance for temperature and humidity conditions in six Australian cities. ANSYS Fluent (2021 R1) software is applied for the numerical simulation. The numerical model is first validated with the available literature before a numerical simulation is conducted to assess each city throughout the year. These include Adelaide, Brisbane, Darwin, Melbourne, Perth, and Sydney. The spray cooling pattern, temperature, and humidity distribution, as well as the evaporation effect on different regions in Australia, is simulated and analysed based on the CFD technique. The results from this study indicate that weather conditions influence spray cooling for all cities, especially in summer. Along the wind tunnel, the temperature significantly drops at the spray cooling area, while the humidity increases. Due to the effect of spray cooling inside the wind tunnel, the temperature at the outlet is still lower than the inlet for all cases. However, the humidity at the outlet is higher than the inlet for all cases.
Li, S, Jiang, Q, Xu, Y, Feng, K, Wang, Y, Sun, B, Yan, X, Sheng, X, Zhang, K & Ni, Q 2023, 'Digital twin-driven focal modulation-based convolutional network for intelligent fault diagnosis', Reliability Engineering & System Safety, vol. 240, pp. 109590-109590.
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Li, T, Lian, S, Zhao, S, Lu, J & Burnett, IS 2023, 'Distributed Active Noise Control Based on an Augmented Diffusion FxLMS Algorithm', IEEE/ACM Transactions on Audio, Speech, and Language Processing, vol. 31, pp. 1449-1463.
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Multichannel active noise control (ANC) systems have been widely investigated for low-frequency noise attenuation over a spatial region. Using a conventional centralized control strategy based on the multichannel filtered-x least mean square (FxLMS) algorithm has been demonstrated to be effective for multichannel ANC systems, but the high computational burden restricts its practical applications. Meanwhile, a decentralized control strategy suffers from stability problems although it has been successful in reducing the computational load. Recently, distributed control strategies, such as the multitask diffusion adaptation scheme, have been introduced to ANC systems and shown to mitigate the stability problems in decentralized systems. However, distributed ANC systems using the diffusion FxLMS algorithm require strong symmetry of acoustic paths because of the dependence on node-based adaptation and neighborhood-based combination. To overcome this limitation, this paper proposes an Augmented Diffusion FxLMS algorithm with neighborhood-based adaptation and node-based combination. A theoretical formulation and convergence analysis are presented and simulations are performed to compare the proposed algorithm with existing ones under different system configurations for tonal, multi-tonal, narrowband and broadband signals. Simulation results demonstrate that the proposed algorithm has the same noise reduction performance as centralized method even if the acoustic paths are strongly asymmetrical, which is superior over existing distributed multitask diffusion strategy.
Li, T, Rao, L, Zhao, S, Duan, H, Lu, J & Burnett, IS 2023, 'An augmented diffusion algorithm with bidirectional communication for a distributed active noise control system', The Journal of the Acoustical Society of America, vol. 154, no. 6, pp. 3568-3579.
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Recent studies on diffusion adaptation for distributed active noise control (DANC) systems have attracted significant research interest due to their balance between computational burden and stability compared to conventional centralized and decentralized adaptation schemes. The conventional multitask diffusion FxLMS algorithm assumes that the converged solutions of all control filters are consistent to each other, which is unrealistic in practice hence results in inferior performance in noise reduction. An augmented diffusion FxLMS algorithm has been proposed to overcome this problem, which adopts a neighborhood-wide adaptation and node-based combination approach to mitigate the bias in the converged solution of the multitask diffusion algorithms. However, the improvement comes at the expense of a higher computational burden and communication cost. All existing DANC systems, including the multitask and augmented diffusion algorithms, assume one-way communication between nodes. By contrast, this paper proposes a bidirectional communication scheme for the augmented diffusion algorithm to further reduce the memory requirement, computational burden, and communication cost. Simulation results in the free field and with measured room impulse responses both demonstrate that the proposed augmented diffusion algorithm with bidirectional communication can achieve a faster convergence speed than that based on one-way communication with a lower memory, computation, and communication burden.
Li, W, Jiang, C, Xiao, J, Xu, C & Deng, M 2023, 'Assessment of Thermal Damage in Polymethyl Methacrylate Using Quasi-static Components of Ultrasonic Waves', Journal of Nondestructive Evaluation, vol. 42, no. 1.
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Li, Y, Wang, X, Zheng, J, Feng, K & Ji, JC 2023, 'Bi-filter multiscale-diversity-entropy-based weak feature extraction for a rotor-bearing system', Measurement Science and Technology, vol. 34, no. 6, pp. 065011-065011.
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Abstract Multiscale-based entropy methods have proven to be a promising tool for extracting fault information due to their high feature extraction ability and easy application. Despite multiscale analysis showing great potential in extracting fault characteristics, it has some drawbacks, such as cutting the data length and neglecting high-frequency information. This paper proposes a bi-filter multiscale diversity entropy (BMDE) to filter comprehensive fault information and address the data length problem. First, the low-frequency information is filtered out by moving average in a multi-low procedure and the high-frequency information is filtered out by an adjacent subtraction in a multi-high procedure. Second, a modified coarse-grained process is introduced to overcome the issue of data length. The validity of the BMDE method is evaluated using both simulation signals and experimental measurements. Results demonstrate that the proposed method offers optimal feature extraction capability with the highest diagnostic accuracy compared with four other traditional entropy-based diagnosis methods.
Li, Z, Gao, W, Kessissoglou, N, Oberst, S, Wang, MY & Luo, Z 2023, 'Multifunctional mechanical metamaterials with tunable double-negative isotropic properties', Materials & Design, vol. 232, pp. 112146-112146.
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Li, Z, Gao, W, Yu Wang, M, Wang, CH & Luo, Z 2023, 'Three-dimensional metamaterials exhibiting extreme isotropy and negative Poisson's ratio', International Journal of Mechanical Sciences, vol. 259, pp. 108617-108617.
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Lin, D, Ji, JC, Wang, X, Wang, Y, Xu, N, Ni, Q, Zhao, G & Feng, K 2023, 'A rigid-flexible coupled dynamic model of a flip-flow vibrating screen considering the effects of processed materials', Powder Technology, vol. 427, pp. 118753-118753.
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Flip-flow vibrating screens (FFVSs) are the critical screening equipment for classifying and dewatering wet materials in mining processing industry. During the screening process, the FFVSs can be regarded as a complex rigid-flexible coupled multi-body system where the screening operation and the dynamics of two screen frames interact. However, there exists no mechanical model that can describe the dynamics of FFVSs during the screening process. The lack of such a dynamic model causes the amplitudes of the main and the floating screen frames unpredictable after the processed materials are loaded on FFVSs, which affects the screening performance and the service life of FFVSs. To bridge this research gap, the loaded dynamic model of a FFVS is established in this paper. First, dynamic tests are performed to investigate the equivalent stiffness and the equivalent damping of the force along the screen surface which is induced by the processed materials. Then, the proposed model of the FFVS is verified qualitatively by existing experimental results, and the effects of the processed materials on the dynamics of the FFVS are explored by comparing the non-load dynamics of the FFVS. Finally, the sensitivities of the main parameters on the dynamic response are investigated based on Sobol's method of global sensitivity analysis. It is shown that the proposed rigid-flexible coupled multi-body dynamic model of the FFVS can not only effectively reveal the dynamic response of FFVS in the screening process, but can also provide a reference for modelling the dynamics of the screening process of other screening equipment.
Lo, Y-C, Blamires, SJ, Liao, C-P & Tso, I-M 2023, 'Nocturnal and diurnal predator and prey interactions with crab spider color polymorphs', Behavioral Ecology and Sociobiology, vol. 77, no. 2.
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Mao, Z, Zhao, L, Huang, S, Jin, T, Fan, Y & Lee, AP 2023, 'Complete region of interest reconstruction by fusing multiview deformable three‐dimensional transesophageal echocardiography images', Medical Physics, vol. 50, no. 1, pp. 61-73.
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AbstractBackgroundWhile three‐dimensional transesophageal echocardiography (3D TEE) has been increasingly used for assessing cardiac anatomy and function, it still suffers from a limited field of view (FoV) of the ultrasound transducer. Therefore, it is difficult to examine a complete region of interest without moving the transducer. Existing methods extend the FoV of 3D TEE images by mosaicing multiview static images, which requires synchronization between 3D TEE images and electrocardiogram (ECG) signal to avoid deformations in the images and can only get the widened image at a specific phase.PurposeThis work aims to develop a novel multiview nonrigid registration and fusion method to extend the FoV of 3D TEE images at different cardiac phases, avoiding the bias toward the specifically chosen phase.MethodsA multiview nonrigid registration and fusion method is proposed to enlarge the FoV of 3D TEE images by fusing dynamic images captured from different viewpoints sequentially. The deformation field for registering images is defined by a collection of affine transformations organized in a graph structure and is estimated by a direct (intensity‐based) method. The accuracy of the proposed method is evaluated by comparing it with two B‐spline–based methods, two Demons‐based methods, and one learning‐based method VoxelMorph. Twenty‐nine sequences of in vivo 3D TEE images captured from four patients are used for the comparative experiments. Four performance metrics including checkerboard volumes, signed distance, mean absolute distance (MAD), and Dice similarity coefficient (DSC) are used jointly to evaluate the accuracy of the results. Additionally, paired t‐tests are performed to examine the significance of the results....
Martins, D, Karimi, M, Maxit, L & Kirby, R 2023, 'Non-negative intensity for a heavy fluid-loaded stiffened plate', Journal of Sound and Vibration, vol. 566, pp. 117891-117891.
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Localisation of sound sources on vibrating structures is a critical part of the design in many engineering applications. In structures with stiffeners, so-called Bloch–Floquet waves are generated due to the interaction between the flexural waves in the host structure and the flexural/torsional waves of the stiffeners. It is known that the Bloch–Floquet waves have a significant contribution to the radiated sound. However, it is not understood which area of the vibrating stiffened structures contributes significantly to the radiation in the far-field. Non-negative intensity (NNI) is a powerful tool developed recently to locate the surface regions on structures that can contribute to the radiated sound power. Although NNI has been used for several distinct structures under different excitations, it has not been considered for analysing structures with stiffeners. In this work, NNI is evaluated for an infinite fluid-loaded stiffened plate subjected to a point force to localise the sources of sound and to shed light on the mechanism involved in the far-field radiation. An analytical model formulated in the wavenumber domain is presented to carry out fast calculations of the plate vibroacoustic responses and the NNI maps. A parametric study is then performed by comparing the vibroacoustic responses with the NNI maps to highlight the capability of NNI for sound source localisation. This is achieved by analysing the results for stiffened/unstiffened structures with excitation on/between the stiffeners, and at frequencies either in a passband or in a stopband. Moreover, the NNI maps are further explained and interpreted using identified Bloch–Floquet radiating bands.
Mohsan, AUH & Wei, D 2023, 'Advancements in Additive Manufacturing of Tantalum via the Laser Powder Bed Fusion (PBF-LB/M): A Comprehensive Review', Materials, vol. 16, no. 19, pp. 6419-6419.
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Additive manufacturing (AM) exhibits a prime increment in manufacturing technology development. The last few decades have witnessed massive improvement in this field of research, including the growth in the process, equipment, and materials. Irrespective of compelling technological advancements, technical challenges provoke the application and development of these technologies. Metal additive manufacturing is considered a prime sector of the industrial revolution. Various metal AM techniques, including Selective Laser Sintering (SLS), Laser Powder Bed Fusion (PBF-LB/M), and Electron Beam Powder Bed Fusion (PBF-EB/M), have been developed according to materials and process classifications. PBF-LB/M is considered one of the most suitable choices for metallic materials. PBF-LB/M of tantalum has become a hot topic of research in the current century owing to the high biocompatibility of tantalum and its high-end safety applications. PBF-LB/M of porous Ta can direct unexplored research prospects in biomedical and orthopedics by adapting mechanical and biomedical properties and pioneering implant designs with predictable features. This review primarily examines the current advancements in the additive manufacturing of tantalum and related alloys using the PBF-LB/M process. The analysis encompasses the evaluation of process parameters, mechanical properties, and potential biological applications. This will offer the reader valuable insights into the present state of PBF-LB/M for tantalum alloys.
Munasinghe, N, Romeijn, T & Paul, G 2023, 'Voxel-based sensor placement for additive manufacturing applications', Journal of Intelligent Manufacturing, vol. 34, no. 2, pp. 739-751.
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Nerse, C, Mohapatra, AR, Oberst, S, Navarro-Payá, D, Etxeberria, J, Matus, JT, Bianco, L, Tucci, MR, Cumino, E, Casacci, LP & Barbero, F 2023, 'Model updating of flowering snapdragon (Antirrhinum litigiosum) biomechanical responses to vibro-acoustic stimuli', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A172-A172.
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The combined variation in gene expression and environmental conditions during flower development can result in phenotypic differences in shape, size, and material composition. Biomechanical responses in flower organs due to external stimuli can be mechanically measured at various levels. Here, we investigate snapdragon (Antirrhinum litigiosum) response to vibro-acoustic stimuli by an interdisciplinary model updating framework. In a climate-controlled setup, sweep signals and artificial signals representative of plant pollinator species were given as excitation input through a loudspeaker to a set of plants; vibrations of the flower organs were measured by laser Doppler vibrometry. Geometric features of the plants were identified using LiDAR combined with photogrammetry, while the density distribution in the flower organs and internal dimensions were estimated using micro-computed tomography scans. A computer model using finite element method was used to identify material properties of the flower organs by combining time domain measurements and dimensional classification. Results demonstrate density and stiffness gradient in the corolla contributing to a modal activity that is adaptive to local conditions and pollinators, but resilient against external noise. The framework outlined herein may give clues to which pollinators induce early-plant responses. [The authors acknowledge the support of the Human Frontier Science Program (HFSP) grant RGP0003/2022.]
Ni, Q, Ji, JC & Feng, K 2023, 'Data-Driven Prognostic Scheme for Bearings Based on a Novel Health Indicator and Gated Recurrent Unit Network', IEEE Transactions on Industrial Informatics, vol. 19, no. 2, pp. 1301-1311.
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The prognosis of bearings is vital for condition-based maintenance of rotating machinery. This article proposes a systematic prognostic scheme for rolling element bearings. The proposed scheme infers the degradation progression by developing a novel health indicator (HI). This novel HI, derived from the spectral correlation, Wasserstein distance, and linear rectification, can reflect the changes in the probability distribution of all cyclic power-spectra over time. In other words, any form of variation in modulation characteristics can be revealed through the proposed novel indicator, even for the weak information buried by the internal or external noise. Furthermore, the developed HI can eliminate random fluctuations that often impair the remaining useful life (RUL) prediction accuracy. Then, a 3 ${\boldsymbol{\sigma }}$ criterion-based technique is introduced to divide health stages. After that, the gated recurrent unit network is employed to predict the RUL of the bearing system, integrated with the Bayesian optimization algorithm to tune the optimal hyperparameters adaptively. This renders the establishment of an intelligent prognosis model with high prediction accuracy and generalization ability. Finally, experimental validations are conducted using the run-to-failure datasets of bearings. The obtained results demonstrate that the proposed HI has better monotonicity, and the proposed prognostic scheme can predict the RUL with high accuracy.
Ni, Q, Ji, JC, Halkon, B, Feng, K & Nandi, AK 2023, 'Physics-Informed Residual Network (PIResNet) for rolling element bearing fault diagnostics', Mechanical Systems and Signal Processing, vol. 200, pp. 110544-110544.
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Various deep learning methodologies have recently been developed for machine condition monitoring recently, and they have achieved impressive success in bearing fault diagnostics. Despite the capability of effectively diagnosing bearing faults, most deep learning methods are tremendously data-dependent, which is not always available in industrial applications. In practical engineering, bearings are usually installed in rotating machinery where speed and load variations frequently occur, resulting in difficulty in collecting large training datasets under all operating conditions. Additionally, physical information is usually ignored in most deep learning algorithms, which sometimes leads to the generated results of low compliance with the physical law. To tackle these challenges, a novel Physics-Informed Residual Network (PIResNet) is proposed for learning the underlying physics that is embedded in both training and testing data, thus providing a physical consistent solution for imperfect data. In the proposed method, a physical modal-property-dominant-generated layer is adopted at first to generate the modal-property-dominant feature. Then, a domain-conversion layer is constructed to enable the feasibility of extracting the discriminative bearing fault features under varying operating speed conditions. Lastly, a parallel bi-channel residual learning architecture that can automatically extract the bearing fault signatures is meticulously established to incorporate the bearing fault characteristics. Experimental datasets under variable operating speeds and loads, and time-varying operating speeds are utilized to demonstrate the superiority of the PIResNet under non-stationary operating conditions.
Nie, X, Liu, L, He, L, Zhao, L, Lu, H, Lou, S, Xiong, R & Wang, Y 2023, 'Weakly-Interactive-Mixed Learning: Less Labelling Cost for Better Medical Image Segmentation', IEEE Journal of Biomedical and Health Informatics, vol. 27, no. 7, pp. 3270-3281.
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Oberst, S & Sepehrirahnama, S 2023, 'A case study on generative learning approaches in a studio and flipped class-room setting for increased learning outcomes', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A59-A59.
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Teaching and learning during Covid-19 have been strongly affected by lockdowns, isolated online learning, and the sudden requirement to alternatively assess students while considering the effect internet-based information sources. Here, we present outcomes on the learning outcome of students returning from distance learning into the face-to-face mode, studying the subject “Embedded Mechatronic Systems” employing increasingly methods of Generative Learning Theory (GLT) in a flipped classroom environment, using studio and project-based learning approaches. By introducing a group project component, the formerly disconnected laboratory components become strongly connected with students being exposed to practical aspects and teamwork, generating reflected reports and videos of their practical work. To overcome the effects of Covi-d19, tighter assessments, and in-person engagements is emphasised. Viva-voces have been introduced and AI invigilated final exams have been altered to in-class room quizzes, while monitoring the cohort’s performance over 3 sessions. Our data indicate that face-to-face learning and hands-on practice with peers using self-testing and self-explaining strategies enacts higher outcomes, opposed to remote modes of teaching. Our results exemplify on how to move back into face-to-face teaching with future steps to increase learning outcomes using the flipped classroom, GLT, and a studio setting being discussed.
Ostermeier, FF, Jaehnert, J & Deuse, J 2023, 'Joint modelling of the order-dependent parts supply strategies sequencing, kitting and batch supply for assembly lines: insights from industrial practice', Production & Manufacturing Research, vol. 11, no. 1.
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Perrin, R, Halkon, BJ & Guo, Z 2023, '(Re-)exploring the normal modes of axisymmetric structures: An English church bell case study', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A74-A74.
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The normal modes of axisymmetric structures are of interest to structural engineers, physicists and musical acousticians. Previously, some of the present authors have made studies of church bells, hand bells, elephant bells, various gongs and rings. Group theoretical arguments have been used, with considerable success, in classifying the normal modes of these structures and in understanding how “beats” arise from split degenerate doublets. It is now pointed out that further information can be obtained from group theory using a variety of additional arguments. In particular, it infers a basic distinction between “in-extensional” and “extensional” types of modes. In the present work, we concentrate on the case of an English church bell, as an example axisymmetric structure, whose normal modes were previously measured in a frequency range of up to about 10 kHz. In that earlier work, the results were analyzed with what was then considered a state-of-the-art finite-element package. We now repeat this exercise with a modern finite-element package to explore the differences between the types of modes and validate the Group theory observations. The agreement with experiment is much improved and some new level of understanding of the spectrum of the bell is achieved.
Phillips, L, Oberst, S & Sepehrirahnama, S 2023, 'Sensor fusion for simultaneous measurement of micro-vibrations', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A141-A142.
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Low-amplitude micro-vibrations are common in nature and engineering, throughout structural applications, and biology. The ability to accurately measure and analyse these vibrations in the presence of noise (unwanted signal content) has far reaching consequences across many fields of acoustics. Methodologies for the enhancement and improvement of such signals are, therefore, sought. We explore the capability of sensor fusion in combination with Kalman filtering (KF), using pairs of accelerometers to improve measurement of low-amplitude micro-vibrations. Prior research of pairing sensor fusion with machine learning approaches like KF, support vector machines, or coherence analysis reported up to 90% reductions in “ghost” detections. This research attempts to extend this success to micro-vibrations where broadband noise, and external perturbations can have dramatic impacts on measurability. A pair of accelerometers has been placed both parallel and perpendicular to the axis of an excitation in pine timber planks of varying dimensions and cuts. Simultaneous measurement of ∼5 N excitations with an automated hammer at varying distances are recorded and patterns observed in the time domain through preliminary analysis in MATLAB. Features identifiable from this data become clearer as compared to conventional approaches and have potential applications in non-invasive early predictive analysis of structures for timber pest control.
Pradhan, S, Zhang, G, Qiu, X, Ji, JC & Parnell, J 2023, 'Robust improved multiband-structured subband adaptive filter for active noise control with impulsive interference', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A121-A121.
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The feedforward filtered-x least mean square algorithm is extensively implemented for active control of broadband noise. However, the control performance is substantially deteriorated due to colored noise and the presence of uncorrelated disturbances near the reference and error sensors. To tackle these issues, in this paper, a robust improved multiband-structured subband adaptive filter based on logarithmic and total least squares method is proposed for active control. Unlike the conventional method of total least squares, the proposed algorithm adopts logarithmic and Rayleigh quotient functions. The closed loop implementation of the improved multiband-structured subband adaptive filter is adopted to meet the delayless requirement. The proposed algorithm is well-suited for environments where the reference signal is highly correlated and the residual noise is contaminated by impulsive noise. Furthermore, an affine combination of the proposed algorithm is developed to meet the complementary requirements of faster convergence and improved noise reduction. Eventually, the stability and computational complexity are studied. Simulation results using measured acoustic paths in an anechoic chamber and a normal room illustrate the effectiveness of the proposed algorithm for controlling broadband noise with impulsive interference. In addition, the tracking control performance is evaluated in a time-varying acoustic environment.
Pradhan, S, Zhang, G, Zhao, S, Niwa, K & Bastiaan Kleijn, W 2023, 'On eigenvalue shaping for two-channel decentralized active noise control systems', Applied Acoustics, vol. 205, pp. 109260-109260.
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Recent works show that two-channel decentralized active noise control (DANC) systems are able to achieve optimal noise reduction performance with guaranteed convergence by proper matrix eigenvalue shaping for each frequency. In this paper, we study the impact of three eigenvalue shaping approaches on the performance of a time-domain two-channel DANC system, where the first two approaches are from the literature and the third one is newly proposed as an extension of one of the two approaches. By theoretical analysis and experimental investigation of the three approaches, it is found that the eigenvalues of the 2 × 2 so-called characteristic matrices in the frequency-domain should be shaped by considering two aspects. Firstly, the two eigenvalues for each matrix need to be pushed towards the positive real axis to ensure stability. Secondly, the eigenvalues inherently affect the two auxiliary filters in the time-domain. They should be shaped so that the two filters have roughly the same magnitudes to facilitate implementation. Simulation results using the measured acoustic paths demonstrate the efficacy of the proposed eigenvalue shaping approach and the adaptive filtering technique for controlling sinusoidal noise, multitone noise, white noise and traffic noise. Experimental result shows the efficacy of the proposed approach for controlling white noise in three dimensional space.
Rahaman, MM, Bhowmick, S, Mondal, RN & Saha, SC 2023, 'A Computational Study of Chaotic Flow and Heat Transfer within a Trapezoidal Cavity', Energies, vol. 16, no. 13, pp. 5031-5031.
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Numerical findings of natural convection flows in a trapezoidal cavity are reported in this study. This study focuses on the shift from symmetric steady to chaotic flow within the cavity. This cavity has a heated bottom wall, a cooled top wall, and adiabatic inclined sidewalls. The unsteady natural convection flows occurring within the cavity are numerically simulated using the finite volume (FV) method. The fluid used in the study is air, and the calculations are performed for different dimensionless parameters, including the Prandtl number (Pr), which is kept constant at 0.71, while varying the Rayleigh numbers (Ra) from 100 to 108 and using a fixed aspect ratio (AR) of 0.5. This study focuses on the effect of the Rayleigh numbers on the transition to chaos. In the transition to chaos, a number of bifurcations occur. The first primary transition is found from the steady symmetric to the steady asymmetric stage, known as a pitchfork bifurcation. The second leading transition is found from a steady asymmetric to an unsteady periodic stage, known as Hopf bifurcation. Another prominent bifurcation happens on the changeover of the unsteady flow from the periodic to the chaotic stage. The attractor bifurcates from a stable fixed point to a limit cycle for the Rayleigh numbers between 4 × 106 and 5 × 106. A spectral analysis and the largest Lyapunov exponents are analyzed to investigate the natural convection flows during the shift from periodic to chaos. Moreover, the cavity’s heat transfers are computed for various regimes. The cavity’s flow phenomena are measured and verified.
Richter, R, Syberg, M, Deuse, J, Willats, P & Lenze, D 2023, 'Creating lean value streams through proactive variability management', International Journal of Production Research, vol. 61, no. 16, pp. 5692-5703.
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Complex product and production systems often result in high variability in the production flow, prohibiting the sustainable implementation of lean practices. In this paper the authors introduce a PDCA cycle to analyse and reduce variability in value streams. The value stream is divided into zones, which are then qualified as stable or unstable. Lean practices can be applied in stable zones, unstable zones remain expert-driven. Measures are introduced to reduce variability in unstable zones with the ultimate target, to turn them into stable zones, extending sustainable lean activities in the value stream, step by step. An IT system is developed to acquire, process and visualise the vast amount of data to provide structured information for experts and management for the reduction of variability in production.
Romeijn, T, Fletcher, DF & de Andrade, A 2023, 'Evaluation of numerical approaches for the simulation of water-flow in gravity-driven helical mineral separators', Separation Science and Technology, vol. 58, no. 14, pp. 2519-2538.
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Saboj, JH, Nag, P, Saha, G & Saha, SC 2023, 'Entropy Production Analysis in an Octagonal Cavity with an Inner Cold Cylinder: A Thermodynamic Aspect', Energies, vol. 16, no. 14, pp. 5487-5487.
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Understanding fluid dynamics and heat transfer is crucial for designing and improving various engineering systems. This study examines the heat transfer characteristics of a buoyancy-driven natural convection flow that is laminar and incompressible. The investigation also considers entropy generation (Egen) within an octagonal cavity subject to a cold cylinder inside the cavity. The dimensionless version of the governing equations and their corresponding boundary conditions have been solved numerically using the finite element method, employing triangular mesh elements for discretization. The findings indicated that incorporating a cold cylinder inside the octagonal cavity resulted in a higher heat transfer (HT) rate than in the absence of a cold cylinder. Furthermore, using the heat flux condition led to a higher average Nusselt number (Nuavg) and a lower Bejan number (Be) than the isothermal boundary condition. The results also showed that HT and Egen were more significant in the Al2O3-H2O nanofluid than the basic fluids such as air and water, and HT increased as χ increased. The current research demonstrates that employing the heat flux condition and incorporating nanoparticles can enhance the rate of HT and Egen. Furthermore, the thermo-fluid system should be operated at low Ra to achieve greater HT effectiveness for nanofluid concerns.
Saha, G, Al-Waaly, AAY, Paul, MC & Saha, SC 2023, 'Heat Transfer in Cavities: Configurative Systematic Review', Energies, vol. 16, no. 5, pp. 2338-2338.
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This study is a systematic review of research on heat transfer analysis in cavities and aims to provide a comprehensive understanding of flow and heat transfer performance in various kinds of cavities with or without the presence of fins, obstacles, cylinders, and baffles. The study also examines the effects of different forces, such as magnetic force, buoyancy force, and thermophoresis effect on heat transfer in cavities. This study also focuses on different types of fluids, such as air, water, nanofluids, and hybrid nanofluids in cavities. Moreover, this review deals with aspects of flow and heat transfer phenomena for only single-phase flows. It discusses various validation techniques used in numerical studies and the different types and sizes of mesh used by researchers. The study is a comprehensive review of 297 research articles, mostly published since 2000, and covers the current progress in the area of heat transfer analysis in cavities. The literature review in this study shows that cavities with obstacles such as fins and rotating cylinders have a significant impact on enhancing heat transfer. Additionally, it is found that the use of nanofluids and hybrid nanofluids has a greater effect on enhancing heat transfer. Lastly, the study suggests future research directions in the field of heat transfer in cavities. This study’s findings have significant implications for a range of areas, including electronic cooling, energy storage systems, solar thermal technologies, and nuclear reactor systems.
Saha, SC, Ahmed, SF, Ahmed, B, Mehnaz, T & Musharrat, A 2023, 'A review of phase change materials in multi-designed tubes and buildings: Testing methods, applications, and heat transfer enhancement', Journal of Energy Storage, vol. 63, pp. 106990-106990.
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Scussel, O, Brennan, MJ, Iwanaga, MK, Almeida, FCL, Karimi, M, Muggleton, JM, Joseph, PF & Rustighi, E 2023, 'Analysis of phase data from ground vibration measurements above a leaking plastic water pipe', Journal of Sound and Vibration, vol. 564, pp. 117873-117873.
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Sepehrirahnama, S, Oberst, S, Croft, BE & Hanson, D 2023, 'Investigating sound absorption in rail tunnels using wave decomposition', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A180-A180.
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Acoustic noise in trains is a more prevalent problem in tunnels as compared to open track scenarios. This is mainly due to less acoustic radiation relative to increasing contributions of reflections and reverberation. Sound absorbing panels on a tunnel wall and in the track four-foot perform better above 1 kHz with absorption coefficients larger than 0.8. To investigate sound absorption below 1 kHz, we employ wave decomposition into incidence, reflection and absorption components for a section of a given underground tunnel design. A Finite Element (FE) 2D model of a carriage and tunnel is developed, representing a tangent portion of a rail track and including the noise power spectra from the rail-wheel interactions for three different roughness scenarios. The FE model, compared to a Ray Tracing one, provides precisely imposed boundary conditions and the pressure field of the entire tunnel interior. Our results can identify the performance of current panels, absorbing significantly less noise power in the lower frequency range, especially within the 0.3–0.5 kHz interval. The insights from wave decomposition analysis can lead to solutions to increase absorption by changing the reflection pattern below 1 kHz band, improving the passenger comfort during a longer train ride.
Singh, K, Saikia, M, Thiyagarajan, K, Thalakotuna, D, Esselle, K & Kodagoda, S 2023, 'Multi-Functional Reconfigurable Intelligent Surfaces for Enhanced Sensing and Communication', Sensors, vol. 23, no. 20, pp. 8561-8561.
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In this paper, we propose a reconfigurable intelligent surface (RIS) that can dynamically switch the transmission and reflection phase of incident electromagnetic waves in real time to realize the dual-beam or quad-beam and convert the polarization of the transmitted beam. Such surfaces can redirect a wireless signal at will to establish robust connectivity when the designated line-of-sight channel is disturbed, thereby enhancing the performance of wireless communication systems by creating an intelligent radio environment. When integrated with a sensing element, they are integral to performing joint detection and communication functions in future wireless sensor networks. In this work, we first analyze the scattering performance of a reconfigurable unit element and then design a RIS. The dynamic field scattering manipulation capability of the RIS is validated by full-wave electromagnetic simulations to realize six different functions. The scattering characteristics of the proposed unit element, which incorporates two p-i-n diodes have been substantiated through practical implementation. This involved the construction of a simple prototype and the subsequent examination of its scattering properties via the free-space measurement method. The obtained transmission and reflection coefficients from the measurements are in agreement with the anticipated outcomes from simulations.
Taheri, MH, Askari, N, Feng, Y, Nabaei, M, Islam, MS, Farnoud, A & Cui, X 2023, 'Swirling flow and capillary diameter effect on the performance of an active dry powder inhalers', Medicine in Novel Technology and Devices, vol. 18, pp. 100240-100240.
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Tran, T, Nerse, C, Oberst, S, Halkon, BJ, Sawalhi, N & Sepehrirahnama, S 2023, 'Vibrational timber characterization through the use of model updating', The Journal of the Acoustical Society of America, vol. 154, no. 4_supplement, pp. A75-A75.
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The characterization of orthotropic materials has challenged the vibration and acoustics community for quite some time. Complex composite materials such as wooden structures require attention to factors including moisture, grain boundaries in addition to macroscopic features. Here we devise a basic model developed by measuring the vibrational response in two separate axes to determine the material characteristics of a timber dowel. A proposed benchtop procedure utilises vibrometers and accelerometers to gather data before the updating process, for which, FEMtools was used. Based on the input material parameters, uncovered by previous studies, provide a starting point for the model updating procedure where experimental mode shapes and frequency responses are correlated to the finite element model. With the focus on radiata pine, the results show radial and tangential values converge similar to previous literature but with variation in the longitudinal direction and shear planes. Overall, this study provides a solid foundation to the characterization process of orthotropic materials like timber which can be further expanded into fields of structural health monitoring, damage detection and potential use in digital twins. The authors acknowledge the support of the Australian Research Council Linkage Project LP200301196.
Wambsganss, A, Bröring, S, Salomo, S & Sick, N 2023, 'Technology strategies in converging technology systems: Evidence from printed electronics', Journal of Product Innovation Management, vol. 40, no. 5, pp. 705-732.
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AbstractNovel technology systems, such as “fiber optics” and “printed electronics,” increasingly emerge at the interface of hitherto unrelated technology areas. As such, new technology systems often arise through technology convergence, characterized by integrating technology components and knowledge from different technology systems, resulting in a novel system architecture. This phenomenon is of utmost societal relevancy but simultaneously poses tremendous challenges for firms' technology strategies. Firms must not only cope with unrelated knowledge rooted in hitherto different technologies but also have to decide deliberately how systemic (i.e., complete technology system) versus focused (i.e., single component of the technology system) their engagement in technology development in the converging technology system ought to be. In addition, firms need to decide strategically to what extent to develop specialized or design knowledge. Extant concepts of technology strategy fall short of capturing this complexity inherent in converging technology systems. Therefore, to address how technology strategies co‐evolve along with the emergence of new technology systems, this study adds a systems perspective to technology strategy by developing the concept of technology system coverage. This novel dimension of technology strategy is formed by the scope (i.e., focused vs. systemic coverage of the technology system) and type of technological knowledge (i.e., specialized or design knowledge). We empirically apply this novel angle of technology strategy to the convergence field of printed electronics. Based on a longitudinal set of 828 patents over 30 years, 74 relevant corporate actors are identified. The underlying taxonomy enables us to reveal four technology strategies and develop five propositions. The results indicate that all firms build design knowledge over time, whereas ...
Wang, D, Han, Q, Xu, S, Zheng, Z, Luo, Q & Mao, J 2023, 'Damage and deformation of new precast concrete shear wall with plastic damage relocation', STEEL AND COMPOSITE STRUCTURES, vol. 48, no. 4, pp. 385-403.
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Wang, E, Chen, C, Zhang, G, Luo, Q, Li, Q & Sun, G 2023, 'Multiaxial mechanical characterization of additively manufactured open-cell Kelvin foams', Composite Structures, vol. 305, pp. 116505-116505.
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Wang, T, Lu, W, Yu, H & Liu, D 2023, 'Modular transfer learning with transition mismatch compensation for excessive disturbance rejection', International Journal of Machine Learning and Cybernetics, vol. 14, no. 1, pp. 295-311.
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Underwater robots in shallow waters usually suffer from strong wave forces, which may frequently exceed robot’s control constraints. Learning-based controllers are suitable for disturbance rejection control, but the excessive disturbances heavily affect the state transition in Markov Decision Process (MDP) or Partially Observable Markov Decision Process (POMDP). This issue is amplified by training-test model mismatch. In this paper, we propose a transfer reinforcement learning algorithm using Transition Mismatch Compensation (TMC), that learns an additional compensatory policy through minimizing mismatch of transitions predicted by the two dynamics models of the source and target tasks. A modular network of learning policies is applied, composed of a Generalized Control Policy (GCP) and an Online Disturbance Identification Model (ODI). GCP is first trained over a wide array of disturbance waveforms. ODI then learns to use past states and actions of the system to predict the disturbance waveforms which are provided as input to GCP (along with the system state). We demonstrated on a pose regulation task in simulation that TMC is able to successfully reject the disturbances and stabilize the robot under an empirical model of the robot system, meanwhile improve sample efficiency.
Wang, X, Thiyagarajan, K, Kodagoda, S & Zhang, M 2023, 'PIPE-CovNet: Automatic In-Pipe Wastewater Infrastructure Surface Abnormality Detection Using Convolutional Neural Network', IEEE Sensors Letters, vol. 7, no. 4, pp. 1-4.
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Wang, Y, Yang, S, Luo, Q, Li, Q & Sun, G 2023, 'Experimental characterization of impact damage in foam-core sandwich structures using acoustic emission, optical scanning and X-ray computed tomography techniques', Composites Part B: Engineering, vol. 265, pp. 110919-110919.
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Wei, Y, Luo, Q, Li, Q & Sun, G 2023, 'On adhesively bonded joints with a mixed failure mode—An experimental and numerical study', Thin-Walled Structures, vol. 192, pp. 110987-110987.
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Williams, P, Kirby, R & Karimi, M 2023, 'The effect of axial boundary conditions on breakout noise from finite cylindrical ducts', International Journal of Mechanical Sciences, vol. 242, pp. 107951-107951.
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Ductborne noise within HVAC and exhaust systems may transfer into the surrounding environment through the walls of the duct. This breakout noise normally needs to be lowered in order to meet health and safety guidelines. This means that the ability of the duct walls to lower breakout noise needs to be predicted during the design stage of the duct systems. Significant work has been conducted into the prediction of breakout noise for infinite length ducts, however there is little to be found on finite length ducts. In particular there are very few studies on the difference between finite and infinite length duct breakout, especially where the noise source lies within the internal fluid. The aim of this work is therefore to investigate the difference in breakout noise between finite length and equivalent infinite length ducts when excited by an internal noise source. This is performed through numerical experiments using the semi analytical finite element method which enables the equations of elasticity for the duct wall, as well as a surrounding fluid, to be accommodated. Axial continuity equations at each end of a finite length elastic duct are then enforced through the point collocation method. It is observed that high sound power levels are emitted at axial resonances of the finite length duct. In the low frequency region these resonances have a narrow bandwidth and are expected to be of little practical significance. However, above the critical frequency the resonance bandwidth increases and this is observed to significantly lower the transverse transmission loss of the duct wall when compared to an infinite length duct. This phenomenon is observed for both clamped and simply supported ducts, as well as for two different internal sound sources. It is concluded that breakout noise from axial resonances in finite length ducts should be examined in design calculations in order to avoid excessive breakout noise.
Wu, J, Jiang, C, Fang, H & Ng, C-T 2023, 'Damage detection in the T-welded joint using Rayleigh-like feature guided wave', NDT & E International, vol. 135, pp. 102806-102806.
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Wu, L, Lee, KMB, Le Gentil, C & Vidal-Calleja, T 2023, 'Log-GPIS-MOP: A Unified Representation for Mapping, Odometry, and Planning', IEEE Transactions on Robotics, vol. 39, no. 5, pp. 4078-4094.
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Whereas dedicated scene representations are required for each different task in conventional robotic systems, this article demonstrates that a unified representation can be used directly for multiple key tasks. We propose the log-Gaussian process implicit surface for mapping, odometry, and planning (Log-GPIS-MOP): a probabilistic framework for surface reconstruction, localization, and navigation based on a unified representation. Our framework applies a logarithmic transformation to a Gaussian process implicit surface (GPIS) formulation to recover a global representation that accurately captures the Euclidean distance field with gradients and, at the same time, the implicit surface. By directly estimating the distance field and its gradient through Log-GPIS inference, the proposed incremental odometry technique computes the optimal alignment of an incoming frame and fuses it globally to produce a map. Concurrently, an optimization-based planner computes a safe collision-free path using the same Log-GPIS surface representation. We validate the proposed framework on simulated and real datasets in 2-D and 3-D, and benchmark against the state-of-the-art approaches. Our experiments show that Log-GPIS-MOP produces competitive results in sequential odometry, surface mapping, and obstacle avoidance.
Xu, Y, Feng, K, Yan, X, Yan, R, Ni, Q, Sun, B, Lei, Z, Zhang, Y & Liu, Z 2023, 'CFCNN: A novel convolutional fusion framework for collaborative fault identification of rotating machinery', Information Fusion, vol. 95, pp. 1-16.
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Xu, Y, Ji, JC, Ni, Q, Feng, K, Beer, M & Chen, H 2023, 'A graph-guided collaborative convolutional neural network for fault diagnosis of electromechanical systems', Mechanical Systems and Signal Processing, vol. 200, pp. 110609-110609.
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Collaborative fault diagnosis has become a hot research topic in fault detection and identification, greatly benefiting from emerging multisensory fusion techniques and newly developed convolutional neural network (CNN) models. Existing CNN models take advantage of various fusion techniques to identify machine health status by utilizing multiple sensory signals. Nevertheless, a few of them are able to simultaneously explore modality-specific features and intrinsic shared features among multi-source signals, limiting the capability of the exploration of multisource data. To address this issue, this paper proposes a novel convolutional network called a graph-guided collaborative convolutional neural network (GGCN) for highly-effective fault diagnosis of electromechanical systems. The main contributions of this study include: (1) developing a novel graph-guided CNN algorithm for collaborative fault detection; (2) establishing a graph reasoning fusion module (GRFM) to explore the inherent correlations between multisource signals; and (3) advancing the current approaches by taking into account both the distribution gap and the intrinsic correlation between different signals simultaneously. The developed GGCN is expected to shed new light on collaborative fault diagnosis using the graph-convolution-based intermediate fusion scheme. Two experimental datasets namely, the cylindrical rolling bearing dataset and the planetary gearbox dataset, are applied in this paper to verify the efficacy of the GGCN. Experimental results demonstrate that GGCN outperforms seven other state-of-the-art approaches, particularly under noisy conditions.
Xu, Y, Zheng, R, Zhang, S, Liu, M & Huang, S 2023, 'CARE: Confidence-Rich Autonomous Robot Exploration Using Bayesian Kernel Inference and Optimization', IEEE Robotics and Automation Letters, vol. 8, no. 10, pp. 6755-6762.
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In this letter, we consider improving the efficiency of information-based autonomous robot exploration in unknown and complex environments. We first utilize Gaussian process (GP) regression to learn a surrogate model to infer the confidence-rich mutual information (CRMI) of querying control actions, then adopt an objective function consisting of predicted CRMI values and prediction uncertainties to conduct Bayesian optimization (BO), i.e., GP-based BO (GPBO). The trade-off between the best action with the highest CRMI value (exploitation) and the action with high prediction variance (exploration) can be realized. To further improve the efficiency of GPBO, we propose a novel lightweight information gain inference method based on Bayesian kernel inference and optimization (BKIO), achieving an approximate logarithmic complexity without the need for training. BKIO can also infer the CRMI and generate the best action using BO with bounded cumulative regret, which ensures its comparable accuracy to GPBO with much higher efficiency. Extensive numerical and real-world experiments show the desired efficiency of our proposed methods without losing exploration performance in different unstructured, cluttered environments.
Ye, K & Ji, JC 2023, 'A Novel Morphing Propeller System Inspired by Origami-Based Structure', Journal of Mechanisms and Robotics, vol. 15, no. 1.
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Abstract For a standard propeller system, the thrust output and the energy dissipation are proportionally dependent on its rotating speed, as its physical characteristics and working conditions are normally fixed during its operation. In order to improve the system performance and meet special application requirements, this paper presents the design of a novel two-stage propeller system with a morphing blade structure for higher thrust output and energy efficiency in operations. Based on the stacked Miura-ori (SMO) pattern, an origami-based structure is designed to enable a change in blade length for a propeller system and thus improve the system performance. The unique snap-through feature of the proposed origami structure is utilized to provide a two-stage working condition according to its rotating speed. The geometric parameter analysis of the SMO structure is first investigated, specifically focusing on the operating mechanism due to the snap-through behavior. Then, the implementation of the SMO structure into a rotating system is studied. The effects of design parameters on the critical transition points, which correspond to two operating states of the proposed propeller system, are numerically discussed. The simulation results confirm the performance improvement in the thrust output and energy-saving. The feasibility of using origami-based structures provides valuable insights into more applications in similar domains, such as fan system and wind turbine blades.
Ye, K & Ji, JC 2023, 'Dynamic analysis of the effects of self-weight induced structural and damping nonlinearity on the performance of an origami-inspired vibration isolator', Journal of Sound and Vibration, vol. 547, pp. 117538-117538.
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Origami-inspired structure has shown strong nonlinearity on its force response during morphing process between phases. When the origami-inspired structure is applied as vibration isolation system, the structural weight is rare to be considered and discussed in the modelling and analysis of vibration isolation system. The effects of the structural self-weight on the dynamic behaviour of the isolation system is not yet fully understood. Thus, this study aims to investigate the influence of the self-weight induced structural and damping nonlinearity on the dynamic performance of an origami-based vibration isolator. A three-mass body, which includes the payload mass, top facets’ mass and bottom facets’ mass, with multiple degree-of-freedom (DOF) motion is proposed to describe the vibration isolation system. First, a quasi-zero-stiffness feature is designed and its static performance is discussed for a set of specifically selected system parameters. Then, the equation of motion for such three-mass body with spring damping considered is derived by using the harmonic balance method (HBM) on its Lagrange's formulation, where the effects of strong nonlinearity on its dynamic performance can be investigated. The analytical expression is verified with the numerical solutions, which are obtained using the Newmark numerical integration method. The influences of each important system parameter on the dynamic nonlinearity are also discussed. It is expected that this study would provide valuable insights to the effects of structural self-weight in a quasi-zero-stiffness isolation system.
Ye, K, Ji, JC & Fitch, R 2023, 'Further investigation and experimental study of an origami structure-based quasi-zero-stiffness vibration isolator', International Journal of Non-Linear Mechanics, vol. 157, pp. 104554-104554.
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A quasi-zero stiffness (QZS) vibration isolator formed from a truss-spring stacked Miura-ori (TS-SMO) origami structure can provide a desired ultra-low dynamic stiffness for vibration isolation while remaining a high-static stiffness for load supporting capacity. This paper further investigates the design parameters and experimentally studies the dynamic performance of the proposed TS-SMO vibration isolation system. The effects of the spring parameters and the initial setup conditions on its static response are analysed. With the proper parameter selection, the resultant supporting force generated by the origami structure can be expressed as a polynomial containing the static force and dynamic force components which does not have the linear term. The displacement transmissibility of the proposed system is calculated to evaluate its isolation performance. Analytical and numerical results are in good agreement and both demonstrate an ultra-low resonance frequency for vibration isolation. The dynamic behaviour of the proposed system is also investigated under different conditions to enhance the vibration isolation performance. A proof-of-concept prototype is designed, fabricated and tested to verify both static and dynamic performances of the TS-SMO QZS isolator. The comparative experimental results between the corresponding linear isolation system and the proposed nonlinear QZS system validate the design of origami-inspired structure for vibration isolation and further confirm the effectiveness of the QZS vibration isolator. It is hoped that this research would provide a solid foundation for designing and modelling the TS-SMO structure adopted for vibration isolation in practical engineering applications.
Yu, X, Wang, F, Luo, Z, Kang, Z & Wang, Y 2023, 'Design of hierarchical microstructures with isotropic elastic stiffness', Materials & Design, vol. 229, pp. 111895-111895.
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Elastic stiffness is one of the most fundamental properties of materials. Design of the microstructures with isotropic stiffness has been an attractive area in the field of metamaterials for over three decades. Despite many classes of isotropic microstructures, exploring novel isotropic microstructures based on innovative mechanics principles has attracted great and continuing interests. This paper presents a novel family of isotropic hierarchical microstructures (Iso-HMs). These hierarchical microstructures are modeled by replacing the solid parts of prescribed single-level microstructures with arrayed microstructures in the second level, where the key task is to identify the correct geometries of the second-level microstructures by conducting parameter space exploring. These Iso-HMs realize isotropic stiffness based on synergistic deformations of the members in the two levels, which is essentially different from existing isotropic microstructures replying on deformations of the members in a single level. Two categories of Iso-HMs with rectangular holes and Vidergauze-type struts are designed. Considering the large size difference in the designed Iso-HMs, additive manufacturing becomes a unique technique for manufacturing the designed Iso-HMs, where the size ratio between the 3D-printed specimens and the minimal features reaches 400:1. Both numerical and experimental results validate the isotropic stiffness of the designed Iso-HMs. Furthermore, the results of a microstructural instability analysis show that the designed Iso-HMs can gain improved buckling strength up to a hundred times higher than their single-level counterparts. The hierarchical design provides a new way to identify novel functional microstructures for applications, and the hierarchical configurations expand the space of the already-known families of isotropic microstructures.
Zareei, SM, Sepehrirahnama, S, Jamshidian, M & Ziaei-Rad, S 2023, 'Three-dimensional numerical simulation of particle acoustophoresis: COMSOL implementation and case studies', Engineering with Computers, vol. 39, no. 1, pp. 735-750.
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Zhang, H, Li, B, Karimi, M, Saydam, S & Hassan, M 2023, 'Recent Advancements in IoT Implementation for Environmental, Safety, and Production Monitoring in Underground Mines', IEEE Internet of Things Journal, vol. 10, no. 16, pp. 14507-14526.
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Zhang, Y, Falque, R, Zhao, L, Chen, Y, Huang, S & Li, H 2023, 'Structure-to-Shape Aortic 3-D Deformation Reconstruction for Endovascular Interventions', IEEE Transactions on Robotics, vol. 39, no. 4, pp. 2954-2972.
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Fluoroscopy-guided endovascular interventions by using X-ray images are challenging. The catheter needs to be manipulated precisely inside the aorta, while only 2-D views from the X-ray fluoroscopy are currently used to help the surgeons. Because the catheter is operated in a 3-D space, a visualization of the deforming 3-D aorta will be useful as guidance for catheter manipulation. Existing 3-D reconstruction methods fall short in only focusing on the deformation reconstruction of the aortic 3-D centerline, or using additional prior knowledge of 3-D catheter position for estimating the aortic 3-D deformation. In this article, we propose a novel framework that reconstructs the aortic 3-D deformation by fusing a preoperative 3-D model and two intraoperative X-ray images. Different from existing methods, the proposed framework reconstructs aortic deformation using a coarse-to-fine pipeline by first reconstructing the aortic 3-D centerline and then reconstructing the 3-D shape. To obtain the accurate features for the fluoroscopic-based 3-D reconstruction, we extract semantic features from the X-ray images, and compute the distance field to efficiently calculate the 3-D-2-D nonrigid correspondence. Nonlinear least squares optimization is used to solve the deformation of both centerline and shape. The proposed framework is validated using phantom and patient datasets, whose results demonstrate improved efficiency and accuracy compared with the existing methods. This framework provides a valuable clinical tool for endovascular interventions.
Zhang, Z, Song, Y, Huang, S, Xiong, R & Wang, Y 2023, 'Toward Consistent and Efficient Map-Based Visual-Inertial Localization: Theory Framework and Filter Design', IEEE Transactions on Robotics, vol. 39, no. 4, pp. 2892-2911.
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This article focuses on designing a consistent and efficient filter for visual-inertial localization given a prebuilt map. First, we propose a new Lie group with its algebra based on which a novel invariant extended Kalman filter (invariant EKF) is designed. We theoretically prove that, when we do not consider the uncertainty of map information, the proposed invariant EKF is able to naturally preserve the correct observability properties of the system. To consider the uncertainty of map information, we introduce a Schmidt filter. With the Schmidt filter, the uncertainty of map information can be taken into consideration to avoid overconfident estimation while the computation cost only increases linearly with the size of the map keyframes. In addition, we introduce an easily implemented observability-constrained technique because directly combining the invariant EKF with the Schmidt filter cannot maintain the correct observability properties of the system that considers the uncertainty of map information. Finally, we validate our proposed system's high consistency, accuracy, and efficiency via extensive simulations and real-world experiments.
Zhao, F, Cao, S, Luo, Q & Ji, J 2023, 'Enhanced design of the quasi-zero stiffness vibration isolator with three pairs of oblique springs: Theory and experiment', Journal of Vibration and Control, vol. 29, no. 9-10, pp. 2049-2063.
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Quasi-zero stiffness vibration isolators have been extensively studied due to superior passive vibration isolation performance. As the quasi-zero stiffness region of the isolators is generally small, the research on their responses to the excitation with high amplitude is currently quite limited. This paper presents an improved design of the quasi-zero stiffness isolator with three pairs of oblique springs to increase the amplitude of the excitation. Theoretical formulations are derived for stiffness and force, and then the influences of three independent parameters on the quasi-zero stiffness region are studied to obtain optimal design parameters. A prototype is fabricated and tested for displacement excitations with amplitudes of 5 mm, 10 mm, and 15 mm in a frequency range of 1.5–10 Hz. The absolute displacement transmissibility of the enhanced quasi-zero stiffness isolator is theoretically and experimentally compared with that of the corresponding linear isolator and that of the previous isolators with three pairs of oblique springs using the same parameter conditions of the loaded mass, the horizontal length of oblique springs, and the vertical spring. The experimental results show that the enhanced design of the quasi-zero stiffness isolator with three pairs of oblique springs can achieve lower displacement transmissibility and deal with the displacement excitation with higher amplitude.
Zhong, J, Zhuang, T, Li, M, Kirby, R, Karimi, M, Lu, J & Zhang, D 2023, 'Sidelobe Suppression for a Steerable Parametric Source Using the Sparse Random Array Technique', IEEE/ACM Transactions on Audio, Speech, and Language Processing, vol. 31, pp. 3152-3161.
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Zuo, W, Luo, Q, Li, Q & Sun, G 2023, 'Effect of thermal and hydrothermal aging on the crashworthiness of carbon fiber reinforced plastic composite tubes', Composite Structures, vol. 303, pp. 116136-116136.
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Adams, C & Oberst, S 1970, 'Modelling of noise due to impulsive excitation using nonlinear time series analysis', Noise and Vibrations Emerging Methods, Auckland, New Zealand.
Akbarzade, M, Oberst, S, Sepehrirahnama, S & Halkon, B 1970, 'Sensitivity and bifurcation analysis of an analytical model of a trapped object in an externally excited acoustic radiation force field', Proceedings of NOVEM23, Noise and Vibration Emerging Methods, Auckland, New Zealand, pp. 1-10.
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Acoustic radiation force (ARF) is a nonlinear acoustic phenomenon for which the acoustic field properties and, to an even greater extent, the explicit dynamics of the object, have received limited attention in the published literature to date. Any oscillations due to the flow field or external perturbations are thereby negligible while the particle is trapped in a stable position. By changing the viewpoint from the acoustic field to the dynamics of a levitated particle, the amplitude and frequency of external oscillation is non-negligible, we ask the question of how external excitation changes the dynamics of the object. We explicitly derive an analytical formulation of a trapped object in the form of a Duffing-like equation with its constants being defined by the object itself, the fluid, the acoustic wave, and the external vibration properties. In this case, the bifurcation behaviour is studied, and we show this together with a sensitivity analysis to represent correct dynamic behaviour in certain regimes of the bifurcation diagram.
Banuelos, DP, Falque, R, Patten, T & Alempijevic, A 1970, 'Skirting Line Estimation Using Sparse to Dense Deformation', 2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), IEEE.
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Bayat, A, Oberst, S & Lai, JCS 1970, 'NUMERICAL SIMULATION OF HEAT TRANSFER IN TERMITE MOUNDS', Proceeding of International Heat Transfer Conference 17, International Heat Transfer Conference 17, Begellhouse.
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Beni, HM, Mortazavi, H, Scataglini, S, Truijen, S, Islam, MS & Paul, G 1970, 'Fluid-Structure Interaction Modeling of Peak Expiratory-Inspiratory Flow in a Stented Upper Airway Using Experimental Data', Springer Nature Switzerland, pp. 106-114.
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Boiar, D, Killich, N, Schulte, L, Hernandez Moreno, V, Deuse, J & Liebig, T 1970, 'Forecasting Algae Growth in Photo-Bioreactors Using Attention LSTMs', Springer International Publishing, pp. 26-37.
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Bourahmoune, K, Ishac, K & Carmichael, M 1970, 'A remote training platform for learning physical skills using an AI powered virtual coach and a novel IoT sensing mat', SIGGRAPH Asia 2023 Posters, SA '23: SIGGRAPH Asia 2023, ACM.
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Chaisumdet, D, Tung Le, D, Khoa Nguyen, DD, Sutjipto, S, Rizvi, D & Paul, G 1970, 'Enhancing the Intuitiveness of Remote Mobile Industrial Robots with Haptic Devices', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, ARRA, Sydney.
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This paper presents the potential integration of Haptic Devices to complement the current Virtual Reality interfaces used for a remote mobile industrial robot. The integration of haptic feedback devices provides proper kinaesthetic awareness to operators, facilitating a feeling of total immersion, as if physically present. The ability to touch and feel, provided by these devices, allows for greater dexterity when operating these robotic systems. It can also solve issues when working within fragile and precision-required environments where current forms of remote teleoperation are lacking. A summary of the teleoperated manipulator, controlled by a haptic device, is outlined in this paper. This system is tested, and the findings from a human user study using the examined control method are presented. The human user study explores the effect of varying environments and modes of visual feedback on the participants’ performance. These results demonstrate the most practical form of visualising an unknown environment when leveraging haptic force feedback.
Cooper-Woolley, B, Darroch, MM, Cong, J, Hendriks, X, Zhu, Q, Xiao, T, Zhao, S & Halkon, B 1970, 'Initial design, development & calibration of MEMS based sound level meter for real-time construction monitoring', 2022 Conference of the Acoustical Society of New Zealand, 2022 Conference of the Acoustical Society of New Zealand, Wellington, New Zealand.
Eager, D & Zhou, S 1970, 'EXPERIMENTAL ANALYSIS OF GREYHOUND RACING TRACK PADDING IMPACT ATTENUATION PERFORMANCE', Proceedings of the International Congress on Sound and Vibration.
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To reduce injuries to greyhounds caused by collisions with fixed racing track objects such as the outside fence or the catching pen structures, padding systems are widely adopted. However, there are currently neither recognized standards nor minimum performance thresholds for greyhound industry padding systems. This research investigates the impact attenuation characteristics of different padding systems for use within the greyhound racing industry for the enhanced safety and welfare of racing greyhounds. A standard head injury criterion (HIC) meter was used to examine padding impact attenuation performance based on the maximum g-force, HIC level and HIC duration. Since padding impact attenuation characteristics are affected by the installation and substrate, on-site testing was conducted to obtain the padding system impact attenuation performance in actual greyhound racing track applications. The test results confirm that the padding currently used within the greyhound industry is adequate for the fence but inadequate when used for rigid structural members such as the catching pen gate supports. Thus, increasing the padding thickness is strongly recommended if it is used at such locations. More importantly, it is also recommended that, after the installation of padding on the track, its impact attenuation characteristics should be tested according to the methodology developed herein to verify the suitability for protecting greyhounds from injury.
Falque, R, Le Gentil, C & Sukkar, F 1970, 'Dynamic Object Detection in Range data using Spatiotemporal Normals', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, Sydney.
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On the journey to enable robots to interact with the real world where humans, animals, and unpredictable elements are acting as independent agents; it is crucial for robots to have the capability to detect dynamic objects. In this paper, we argue that the detection of dynamic objects can be solved by computing the spatiotemporal normals of a point cloud. In our experiments, we demonstrate that this simple method can be used robustly for LiDAR and depth cameras with performances similar to the state of the art while offering a significantly simpler method.
Falque, R, Vidal-Calleja, T & Alempijevic, A 1970, 'Semantic Keypoint Extraction for Scanned Animals using Multi-Depth-Camera Systems', 2023 IEEE International Conference on Robotics and Automation (ICRA), 2023 IEEE International Conference on Robotics and Automation (ICRA), IEEE.
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Fan, Y & Liu, D 1970, 'An equivalent two section method for calculating the workspace of multi-segment continuum robots', 2023 IEEE International Conference on Robotics and Automation (ICRA), 2023 IEEE International Conference on Robotics and Automation (ICRA), IEEE.
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Hossain, MI & Eager, D 1970, 'Predicting greyhound speed in the race by creating a historical data plane of race data', Proceedings of the 18th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering, International Symposium on Computer Methods in Biomechanics and Biomedical Engineering, Paris, France.
Khoa Le, DD, Hu, G, Liu, D, Khonasty, R, Zhao, L, Huang, S, Shrestha, P & Belperio, R 1970, 'The QUENDA-BOT: Autonomous Robot for Screw-Fixing Installation in Timber Building Construction', 2023 IEEE 19th International Conference on Automation Science and Engineering (CASE), 2023 IEEE 19th International Conference on Automation Science and Engineering (CASE), IEEE.
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Li, T, Song, Y, Walker, P, Pan, K, van de Graaf, VA, Zhao, L & Huang, S 1970, 'A Closed-Form Solution to Electromagnetic Sensor Based Intraoperative Limb Length Measurement in Total Hip Arthroplasty', Springer Nature Switzerland, pp. 365-375.
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Manitta, M, Jayasuriya, M & Liu, D 1970, 'A Vector Field-Based Method for Human Action Representation and Recognition During Human-Robot Collaboration.', CASE, 2023 IEEE 19th International Conference on Automation Science and Engineering (CASE), IEEE, pp. 1-7.
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Mitchell, C, Best, G & Hollinger, G 1970, 'Sequential Stochastic Multi-Task Assignment for Multi-Robot Deployment Planning', 2023 IEEE International Conference on Robotics and Automation (ICRA), 2023 IEEE International Conference on Robotics and Automation (ICRA), IEEE.
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Nerse, C, Oberst, S, Navarro-Payá, D, Etxeberria, J, Matus, JT, Bianco, L, Casacci, LP & Barbero, F 1970, 'PROPENSITY TO EFFICIENTLY TRANSMIT VIBRATIONS IN SNAPDRAGONS IN RESPONSE TO VIBROACOUSTIC SIGNALLING', Proceedings of the International Congress on Sound and Vibration, Proceedings of the 29th International Congress on Sound and Vibration, Prague, Czech Republic.
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The coevolution of angiosperms and pollinating insects has drawn a diverse repertoire of plant-pollinator interactions leading to different mechanisms of pollen transfer. Buzz pollination is a dynamic pollen removal process between plants and insects that is thought to have emerged due to ecological and evolutionary factors. The floral morphology in buzz-pollinated flowers restricts the pollen access to non-pollinating insects to increase the conditions that favour fertilisation. Efficient pollinators such as bumblebees use sonication to vibrate the anthers of the flower, thereby causing pollen grains to be expelled through the apical pores of the anthers. Recent studies have shown that the conditions in which buzz pollination occurs vary with respect to the floral morphology and vibration signals produced by the bees mainly determined by the duration, amplitude, and frequency of the vibration. The structural topology and material properties of the flower also induce resonance and damping behaviour, thus mediating the transmission of substrate-borne vibrations. Along with the best-studied mechanism of buzz pollination, it is increasingly clear that vibroacoustic (VA) signals may have played a role in co-evolutionary responses that significantly impact several aspects of plant and insect ecology. However, studies on the material properties in terms of VA transmission are still in their infancy. Therefore, in this study, we numerically investigate the sensitivity of the floral topology on transmission of vibrations from a source signal. For this purpose, stamen structures at different scales and loading conditions are modelled and analysed in a finite element software package. A representative VA signal is implemented as the excitation at locations impacting the flower during feeding events. The results demonstrate that natural frequencies and mode shapes of the stamen may influence the conditions in which the vibrational energy is scattered across the fl...
Nugroho, KA, Amirul Haq, M, Wang, C-K, Ruan, S-J, Polikarpov, M, Wagstyl, D & Deuse, J 1970, 'Towards Smart Manufacturing using Reinforcement Learning in a Sparse-Rewarded Environment for Through-Hole Technology', 2023 IEEE 12th Global Conference on Consumer Electronics (GCCE), 2023 IEEE 12th Global Conference on Consumer Electronics (GCCE), IEEE.
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Nuñez, A, Kong, FH, Seiler, KM, Cantos, AG & Fitch, R 1970, 'Optimal ship routing via Spherical Visibility Graphs', OCEANS 2023 - Limerick, OCEANS 2023 - Limerick, IEEE.
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Oberst, S, Sepehrirahnama, S, Halkon, B, Lai, JCS, Atkinson, T & Evans, TAE 1970, 'A microactuator device for the detection of termite damage in timber poles', International Union of Forest Research Organisations, Cairns.
Oberst, S, Sepehrirahnama, S, Nerse, C, Brodzeli, Z, Lai, JCS, Mankowski, M, Atkinson, T, Arango, R, Kirker, G & Evans, T 1970, 'Towards a microactuator-sensing network for structural health monitoring of timber poles', Proceedings IRG Annual Meeting, International Research Group on Wood Protection, The International Research Group on Wood Protection, Cairns, Queensland, Australia, pp. 1-9.
Ostermeier, F, West, N & Deuse, J 1970, 'How Moderator Variables Affect Scheduling Objectives in Unpaced Mixed-Model Assembly Lines', Lecture Notes in Production Engineering, Springer International Publishing, pp. 419-431.
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Besides the sequence itself also additional factors serving as moderator variables affect the value of scheduling objectives. For mixed-model assembly lines, especially number and heterogeneity of different products, their volume mix proportions, average workload of the jobs to process and the degree of grouping of identical jobs within the sequence play a major role. By means of a simulation study based on data from a real unpaced mixed-model assembly line in the automotive industry, this work analyzes the impact of these moderating variables on various scheduling objectives. The analyzed scheduling objectives encompass flow-related objectives like mean flow time, productivity-related objectives like makespan, customer-related objectives like mean earliness, the supplier-related objective part usage rate variation and the human-related objectives mean learning effect and mean deterioration effect per job. Simulation scenarios are defined that differ regarding number and heterogeneity of products from three homogeneous to seven more heterogeneous products. Within every simulation scenario the volume mix proportions of the products, and inherently also the average workload of jobs, are systematically varied. Every simulation scenario is analyzed for five sequence types differing in the degree of grouping of identical jobs. For almost all scheduling objectives, strong dependencies on the volume mix proportions can be perceived, particularly for mean flow time. Homogeneous volume mixes with a dominating product in the mix often lead to other objective values compared to heterogeneous volume mixes that allow using alternation effects between various products in a sequence. Concerning degree of grouping, while some scheduling objectives like part usage rate variation are always strongly affected by the degree of grouping for every volume mix, other objectives like throughput show strong dependence only for some mixes and makespan does not even show any tende...
Pan, K, Zhang, S, Zhao, L, Huang, S, Zhang, Y, Wang, H & Luo, Q 1970, '3D Reconstruction of Tibia and Fibula using One General Model and Two X-ray Images', 2023 IEEE International Conference on Robotics and Automation (ICRA), 2023 IEEE International Conference on Robotics and Automation (ICRA), IEEE, pp. 4732-4738.
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The 3D reconstruction of patient specific bone models plays a crucial role in orthopaedic surgery for clinical evaluation, surgical planning and precise implant design or selection. This paper considers the problem of reconstructing a patient-specific 3D tibia and fibula model from only two 2D X-ray images and one 3D general model segmented from the lower leg CT scans of one randomly selected patient. Currently, the bone 3D reconstruction mainly relies on computed tomography (CT) and magnetic resonance imaging (MRI) scanning-based mode segmentation which result in high radiation exposure or expensive costs. While, the proposed algorithm can accurately and efficiently deform a 3D general model to achieve a patient-specific 3D model that matches the patient's tibia and fibula projections in two 2D X-rays. The algorithm undergoes a preliminary deformation, 2D contour registration, and opti-misation based on the deformation graph that represents the shape deformation of models. Evaluations using simulations, cadaver and in-vivo experiments demonstrate that the proposed algorithm can effectively reconstruct the patient's 3D tibia and fibula surface model with high accuracy.
Parnell, J 1970, 'Challenges in predicting and managing construction noise impacts in urban environments. Case studies from Sydney, Australia', INTER-NOISE and NOISE-CON Congress and Conference Proceedings, Institute of Noise Control Engineering (INCE), pp. 6844-6852.
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Approval of major infrastructure projects in Australia is contingent on a vigorous environmental assessment process demonstrating that the impacts from such proposals are acceptable and can be satisfactorily managed. As part of this process, an assessment of construction noise is undertaken by predicting the level and duration of impact. Given the scale, complexity and programs for delivery of major infrastructure projects such as the Sydney Metro, the approach to assessment of environmental impacts is typically undertaken based on early concept designs, and assumptions which enable potential worst-case impacts to be considered. Ongoing design development and construction methodologies continue to occur, and are finalised by the contractor responsible for delivering the package of works for the project. Layers of conservatism could therefore be built into the process to ensure that environmental impacts are understood, and appropriate mitigation measures are considered. Moreover, common predictive noise modelling tools are believed to under-estimate the level of barrier insertion loss provided by residential buildings in urban scenarios, further exacerbating the over-prediction of construction noise impacts. By use of case studies, the present paper examines the challenges of assessing and managing construction noise associated with a major infrastructure project in Sydney, Australia.
Powell, K, Kodagoda, S & Vidal-Calleja, T 1970, 'Towards Context Aware Emotion Recognition in HRI for Social Robots', Australasian Conference on Robotics and Automation, ACRA.
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Social robots are becoming more prevalent in our daily environments but continue to struggle communicating in human-robot interactions, often misunderstanding people and thus making the interaction uncomfortable. Many attempts have been made to improve their understanding of people and their emotions but they still lack the socio-emotional intelligence humans often use in human-human interactions. A new approach previously explored in computer science is using context emotion recognition to interpret a scene for clues to a person’s emotional state. In this paper, we state that context emotion recognition will benefit the fields of human-robot interaction and social robotics. Further, we extend upon the EMOTIC model successfully adding a graphical representation of the emotion probabilities over time to the model output and with the addition of a facial feature extractor module that obtains an encouraging improvement over the original model. The algorithm was validated through data coming from two robotic platforms, namely PR2 and Pepper. The results show a promising way towards context aware emotion recognition in human-robot interactions with social robots, with 88% accuracy when comparing with 66% accuracy of the base model.
Ranasinghe, U, Abeyrathne, S, Samaranayake, L, Weerakoon, T, Harischandra, N & Dissanayake, G 1970, 'Enhanced Frequency Domain Analysis for Detecting Wild Elephants in Asia using Acoustics', 2023 IEEE 17th International Conference on Industrial and Information Systems (ICIIS), 2023 IEEE 17th International Conference on Industrial and Information Systems (ICIIS), IEEE, pp. 140-145.
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Human-elephant conflict in Asia and Africa calls for an early warning system to reduce risks and harm for both elephants and humans. Acoustic based warning systems offer a promising solution due to their non-invasive and cost-effective nature. In this paper, we propose a novel approach for detecting wild elephants using acoustic signals, targeting the Asian elephant population in Sri Lanka. The proposed method introduces a unique data preprocessing technique, followed by feature extraction using a deep convolutional neural network followed by fully connected layers for classification. Spectro-grams are used as input data, and transfer learning is employed with YAMNet model layers. Additionally, we have developed a hardware system capable of capturing infra sound signals, although a detailed description of the system is beyond the scope of this paper as it is crucial for detecting elephant activity. The proposed method is evaluated on a large data set recorded under natural field conditions in Sri Lanka, and it demonstrates 97.77% accuracy in detecting elephants and robustness to noise sources. Proposed approach has the potential to develop into a non-invasive early warning system for elephant detection in the wild, contributing to the mitigation of human-elephant conflict and wildlife preservation.
Röhrl, K, Bauer, D, Patten, T & Vincze, M 1970, 'TrackAgent: 6D Object Tracking via Reinforcement Learning', Computer Vision Systems, Springer Nature Switzerland, pp. 323-335.
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Tracking an object’s 6D pose, while either the object itself or the observing camera is moving, is important for many robotics and augmented reality applications. While exploiting temporal priors eases this problem, object-specific knowledge is required to recover when tracking is lost. Under the tight time constraints of the tracking task, RGB(D)-based methods are often conceptionally complex or rely on heuristic motion models. In comparison, we propose to simplify object tracking to a reinforced point cloud (depth only) alignment task. This allows us to train a streamlined approach from scratch with limited amounts of sparse 3D point clouds, compared to the large datasets of diverse RGBD sequences required in previous works. We incorporate temporal frame-to-frame registration with object-based recovery by frame-to-model refinement using a reinforcement learning (RL) agent that jointly solves for both objectives. We also show that the RL agent’s uncertainty and a rendering-based mask propagation are effective reinitialization triggers.
Schwenken, J, Klupak, C, Syberg, M, West, N, Walker, F & Deuse, J 1970, 'Development of a Transdisciplinary Role Concept for the Process Chain of Industrial Data Science', Lecture Notes in Networks and Systems, Springer Nature Singapore, pp. 81-88.
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In recent years, there has been an increasing interest in using industrial data science (IDS) in manufacturing companies. Structured IDS projects proceed according to process models such as the cross industry standard process for data mining (CRISP-DM), knowledge discovery in databases (KDD), or the process chain of industrial data science. Because of the process Chain’s transdisciplinary procedure, the participation of different people in the analysis with different tasks and competencies is necessary. Therefore, a concept to define specific roles is required, since it provides unequivocal descriptions of the respective tasks. As no role concept for the process chain of IDS exists, this paper develops and presents a transdisciplinary role concept including the four essential roles: Data engineer, analyst, user, and project manager. These roles are described in terms of their characteristics to enable structured cooperation between them. In addition, this paper presents the AKKORD platform for learning and collaboration, which especially should make an important contribution for small and medium-sized enterprises (SME) to develop knowledge in the usage of the process chain of IDS. The platform provides the opportunity for the users to train the essential roles with their characteristics in the company through targeted competence development.
Sepehrirahnama, S 1970, 'Elastic wave reflection in beams with acoustic black hole termination under axial excitations', INTER-NOISE and NOISE-CON Congress and Conference Proceedings, Noise and Vibration: Emerging Methods, Institute of Noise Control Engineering (INCE), Auckland, New Zealand, pp. 186-195.
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The wave speed in structures can be controlled by altering their stiffness through variations of the geometry and dimensions of the cross-section along its length. Theoretically, slowing down the elastic waves can lead to a zero-reflection effect, which is referred to as acoustic black hole (ABH). ABH has been demonstrated in metallic structures with isotropic-like material properties; while the effects of material anisotropy such as wood mechanical properties on the ABH effect are yet to be explored. We demonstrate numerically and experimentally the ABH effect in wood beams (Pinus radiata) of different lengths by applying an exponential reduction of the circular cross-section. The beams are knot-free and made of cuts of 40mm, 80mm, 100mm, 120mm and 160mm length along the grain, which could lead to a small Poisson ratio by about one order of magnitude. An increase in moisture content of the ABH wood beams by about 8-10% of the dry weights(N=5 samples) and a higher volume fraction of fibrous grains have been shown to reduce the wave reflection, as the drier and lower volume fraction the fibre, the higher the reflection becomes. This work can lead to design of novel elastic wave-guides for timber structures as used in buildings and wooden infrastructure or construction processes
Sepehrirahnama, S, Sansom, T, Lai, JCS & Oberst, S 1970, 'DESIGN OF A MINIATURISED MICRO-FORCE PLATE TO STUDY THE LOCOMOTION OF SMALL ARTHROPODS', Proceedings of the International Congress on Sound and Vibration, 29, International Institute of Acoustics and Vibrations (IIAV) - IIAV CZECH s.r.o., Prague, Czech Republic.
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Walking insects exhibit various types of locomotory gaits to adjust to their environment, for foraging activities, defence, building, courtship and communication. Among hexapods, the walking gaits of ants had been studied by measuring the ground reaction force from their steps with a Micro-Force Plate, which is a bespoke and sensitive thin plate mounted on a structure similar to the suspension system of a vehicle. Compared to ants, termites have quieter footsteps on the same substrate (peak velocity of 0.004 ms-1 compared to 0.4 ms-1 for ants). To study common gaits of small arthropods, we designed a miniaturised micro-force plate capable of measuring forces in the order of 1 μN in the z-direction (out-of-plane); an order of magnitude smaller than the one used for study of ants walking gaits. This is achieved by more compliant beams (halved width, at least 50% longer in the x and y-directions) from 3D-printed resin with minimum required curing; compared to the one for ants from the completed stereolithography. The improved design is assessed numerically by characterising its vibration response in terms of settling time due to an axial force excitation. Our micro-force plate can be used to increase the signal-to-noise ratio, as measured for a 3D-printed prototype, and better resolved force (approximately 1 μN without using any MEMS component). Results presented here indicate our micro-force plate is suitable for studying quiet tiny hexapods to provide insights for bio-inspired engineering of robotic locomotion systems.
Sharma, S, Brian Lee, KM, Brown, M & Best, G 1970, 'Instructing Robots with Natural Language via Bi-RNNs for Temporal Logic Translation', Australasian Conference on Robotics and Automation, ACRA.
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We consider the problem of planning trajectories that satisfy natural language instruction. We explore translating natural language commands to temporal logic formulae to resolve ambiguities for planning. Our main contribution is a new bi-directional recurrent neural network (Bi-RNN) architecture for this translation task. We experimentally show that the proposed Bi-RNN architecture achieves 1.6% better accuracy, 20% faster inference time, and 98% faster training time compared to leading models owing to bidirectional processing. The overall system, including a planning algorithm, exhibits useful diverse behaviours that satisfy given instructions.
Stephen, B, Kacprzak, M, Li, B, Guo, T, Wang, Y, Viswanathan, V, Kodagoda, S, Thiyagarajan, K & Vitanage, D 1970, 'Use of Machine Learning and Robotics To Target Renewals in Concrete Gravity Sewers', OzWater'23, OzWater'23, Sydney.
Suchi, M, Neuberger, B, Salykov, A, Weibel, J-B, Patten, T & Vincze, M 1970, '3D-DAT: 3D-Dataset Annotation Toolkit for Robotic Vision', 2023 IEEE International Conference on Robotics and Automation (ICRA), 2023 IEEE International Conference on Robotics and Automation (ICRA), IEEE.
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Sukkar, F, Moreno, VH, Vidal-Calleja, T & Deuse, J 1970, 'Guided Learning from Demonstration for Robust Transferability', 2023 IEEE International Conference on Robotics and Automation (ICRA), 2023 IEEE International Conference on Robotics and Automation (ICRA), IEEE, London, United Kingdom, pp. 5048-5054.
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Learning from demonstration LfD has the potential to greatly increase the applicability of robotic manipulators in modern industrial applications Recent progress in LfD methods have put more emphasis in learning robustness than in guiding the demonstration itself in order to improve robustness The latter is particularly important to consider when the target system reproducing the motion is structurally different to the demonstration system as some demonstrated motions may not be reproducible In light of this this paper introduces a new guided learning from demonstration paradigm where an interactive graphical user interface GUI guides the user during demonstration preventing them from demonstrating non reproducible motions The key aspect of our approach is determining the space of reproducible motions based on a motion planning framework which finds regions in the task space where trajectories are guaranteed to be of bounded length We evaluate our method on two different setups with a six degree of freedom DOF UR5 as the target system First our method is validated using a seven DOF Sawyer as the demonstration system Then an extensive user study is carried out where several participants are asked to demonstrate with and without guidance a mock weld task using a hand held tool tracked by a VICON system With guidance users were able to always carry out the task successfully in comparison to only 44 of the time without guidance
Sukkar, F, Moreno, VH, Vidal-Calleja, T & Deuse, J 1970, 'Guided Learning from Demonstration for Robust Transferability'.
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Learning from demonstration (LfD) has the potential to greatly increase theapplicability of robotic manipulators in modern industrial applications. Recentprogress in LfD methods have put more emphasis in learning robustness than inguiding the demonstration itself in order to improve robustness. The latter isparticularly important to consider when the target system reproducing themotion is structurally different to the demonstration system, as somedemonstrated motions may not be reproducible. In light of this, this paperintroduces a new guided learning from demonstration paradigm where aninteractive graphical user interface (GUI) guides the user duringdemonstration, preventing them from demonstrating non-reproducible motions. Thekey aspect of our approach is determining the space of reproducible motionsbased on a motion planning framework which finds regions in the task spacewhere trajectories are guaranteed to be of bounded length. We evaluate ourmethod on two different setups with a six-degree-of-freedom (DOF) UR5 as thetarget system. First our method is validated using a seven-DOF Sawyer as thedemonstration system. Then an extensive user study is carried out where severalparticipants are asked to demonstrate, with and without guidance, a mock weldtask using a hand held tool tracked by a VICON system. With guidance users wereable to always carry out the task successfully in comparison to only 44% of thetime without guidance.
Sukkar, F, Savery, R, Haque, N, Le Gentil, C, Falque, R & Vidal-Calleja, T 1970, 'A Robotic System For Imitating Human Percussionists', Australasian Conference on Robotics and Automation, ACRA, Australasian Conference on Robotics and Automation, Sydney.
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Robot musicians have the potential to revolutionise the way humans perceive and create music. Recent breakthroughs in this field have tended to focus more on the digital generation of music. Instead, we address how a musician’s physical embodiment can be translated to a robotic arm. Robots endowed with human-like musical capability open the possibility for wider applications such as human-robot bands, musical education and musical art. Prior work in this area tends to rely on pre-programmed actuation which is limited to simple motion and sound. In this paper, we propose a robotic system capable of imitating a human musician, with a focus on percussion instruments. Our system consists of a method for recording the human demonstration, a compact continuous representation of the demonstrated motion and a motion reproduction method which considers the dynamic constraints of the robot. We present results of our system and show that it is capable of closely reproducing the motion of the human percussionist.
Tomidei, L, Sick, N, Guertler, M, Schallow, J, Lenze, D & Deuse, J 1970, 'Dynamic value stream mapping: How Industry 4.0 can help us to learn to see better', 9th Changeable, Agile, Reconfigurable and Virtual Production Conference, Bologna, Italy.
Tomidei, L, Sick, N, Guertler, M, Schallow, J, Lenze, D & Deuse, J 1970, 'Dynamic Value Stream Mapping—How Industry 4.0 Can Help Us to Learn to See Better', Springer International Publishing, Daejeon City, South Korea, pp. 753-762.
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Trung Le, NT, Bray, E, Brian Lee, KM & Best, G 1970, 'Adaptive Trajectory Library Planner for Fast Outdoor Robots', Australasian Conference on Robotics and Automation, ACRA.
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High-speed autonomous operation in outdoor environments requires fast computation of dynamically feasible, collision-free paths. To this end, we propose a new local path planning algorithm called Adaptive Trajectory Library. This approach relies on the selection of a suitable trajectory from a precomputed library to reduce online computation. A subset of trajectories that are dynamically feasible are considered, from which one is chosen to best move the robot towards a goal location while avoiding obstacles. In simulated experiments, the proposed algorithm significantly outperforms the Dynamic Window Approach [Fox et al., 1997] with 84.2 % less travel time and 39.5 % shorter path length. Hardware experiments in outdoor environments show that the proposed planner is able to reliably compute paths for a robot to follow to reach goals at high speeds in off-road terrain while avoiding obstacles.
Tung Le, D, Sutjipto, S, Khoa Nguyen, DD, Long Vu, T, Thong Vu, PD, Munasinghe, N & Paul, G 1970, 'HALO: a Rock Scaling Mobile Manipulator with Interactive Virtual Reality Live Digital Twin', Australasian Conference on Robotics and Automation, ACRA, Sydney.
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The High Access Localised Operations (HALO) system is a mobile manipulator that amalgamates advancements in digital twins, and virtual reality (VR) to enable safer rock scaling operations in the mining industry. Currently, the essential geotechnical activity of rock scaling is performed by certified workers suspended on the side of the rock wall, who perform the physically demanding task of removing loose rock debris. The HALO system enables a remote operator immersed in a VR environment that visualises the digital twin of the robot and its sensor data in real-time to interact with the robot intuitively. This eliminates the need for people to be exposed to the hazards associated with performing manual rock scaling, while enabling them to apply their existing expertise when operating the robot in VR. In this work, we present a summary of the HALO hardware and its interaction architecture, encompassing a framework for real-time remote scene reconstruction and natural interaction. Findings from preliminary site trials are also be presented to provide preliminary evaluation of the system.
Wambsganss, A, Tomidei, L, Sick, N, Bröring, S, Salomo, S & Schultz, C 1970, 'Machine-based anticipation of converging technology systems: The case of printed electronics', International Society for Professional Innovation Management, Ljubljana, Slovenia.
Wang, Q, Liu, D, Carmichael, MG & Lin, C-T 1970, 'Robot Trust and Self-Confidence Based Role Arbitration Method for Physical Human-Robot Collaboration', 2023 IEEE International Conference on Robotics and Automation (ICRA), 2023 IEEE International Conference on Robotics and Automation (ICRA), IEEE, ENGLAND, London, pp. 9896-9902.
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Role arbitration in human-robot collaboration (HRC) is a dynamically changing process that is affected by many factors such as physical workload, environmental changes and trust. In order to address this dynamic process, a trust-based role arbitration method is studied in this research. A computational model of robot trust and self-confidence (TSC) in physical human-robot collaboration (pHRC) is proposed. The TSC model is defined as a function of objective robot and human co-worker performance. A role arbitration method is then proposed based on the TSC model presented. The human-in-the-loop experiments with a collaborative robot are conducted to verify the TSC-based role arbitration method. The results show that the proposed method could achieve superior human-robot combined performance, reduce human co-workers' workload, and improve subjective preference.
Wu, L, Gentil, CL & Vidal-Calleja, T 1970, 'Pseudo Inputs Optimisation for Efficient Gaussian Process Distance Fields', 2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), IEEE.
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Xing, V, Zhao, L & Best, G 1970, 'CoordLight-YOLOv5: A Lightweight Object Detection Algorithm for Autonomous Motorsport', Australasian Conference on Robotics and Automation, ACRA.
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Autonomous motorsport is a rapidly developing field, among which autonomous racing based on cone tracks is a challenging testing and racing environment. Object detection is one of its indispensable technologies. We propose an improved lightweight model, CoordLightYOLOv5, motivated by autonomous racing projects that require a high frame rate and detection accuracy by onboard embedded computing. In the proposed method, we deleted large object detection feature maps from the backbone and neck network in order to reduce model training and detection time and reduce model computational costs. Furthermore, we introduce CoordConv layer in the neck network to enhance object localisation ability in Cartesian coordinates without using spatial transformations. Our experiments with five autonomous racing datasets show that compared to YOLOv5s, the average number of model parameters is reduced by 91.5%, the average floating-point operation is reduced by 78%, the detection speed has been increased from the original 94 frames per second to 117 frames per second, and the average detection accuracy decreased by only 2.5%.
Xu, B, Guertler, M & Sick, N 1970, 'Analyzing Industry 4.0 Adoption Barriers of Small and Medium-sized Enterprises and Existing Support', IEEE Conference on Engineering Informatics, Melbourne, pp. 1-10.
Zhang, Y, Cheng, C, Falque, R, Zhao, L, Huang, S & Chen, Y 1970, '3D Intra-articular Dense Reconstruction from Arthroscopic Images', 2023 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2023 IEEE International Conference on Robotics and Biomimetics (ROBIO), IEEE.
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