ORCID Profile
0000-0002-8946-9993
Current Organisations
University of Queensland
,
University of New South Wales
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Mechanical Engineering | Acoustics and Noise Control (excl. Architectural Acoustics) | Behavioural Ecology | Mechanical Engineering | Interdisciplinary Engineering | Sociobiology And Behavioural Ecology | Other Artificial Intelligence | Mathematics Not Elsewhere Classified | Atomic, Molecular, Nuclear, Particle and Plasma Physics | Ecology | Microwave And Millimetrewave Technology | Engineering And Technology Not Elsewhere Classified | Aerospace Engineering | Artificial Intelligence and Image Processing | Electrical and Electronic Engineering | Aerodynamics (excl. Hypersonic Aerodynamics) | Signal Processing | Turbulent Flows | Optimisation | Information Systems Management | Computational Fluid Dynamics | Interdisciplinary Engineering Not Elsewhere Classified | Research, Science And Technology Policy | Materials Engineering Not Elsewhere Classified | Other Plasma Physics | Fluid Physics |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Biological Sciences | Control of Pests, Diseases and Exotic Species in Urban and Industrial Environments | Preserving the built environment | Other | Control of pests and exotic species | Computer software and services not elsewhere classified | Expanding Knowledge in Engineering | Technological and organisational innovation | Metals (composites, coatings, bonding, etc.) | Emerging Defence Technologies | Control of pests and exotic species | Aerospace equipment | Economic issues not elsewhere classified | Agricultural chemicals | Control of Plant Pests, Diseases and Exotic Species in Forest and Woodlands Environments | Industrial Chemicals and Related Products not elsewhere classified | Other
Related Links
Publications
Control of shear cutting noise: Effectiveness of passive control measures
Publisher: SAGE Publications
Date: 07-2002
DOI: 10.1260/09574560260370079
Abstract: In an attempt to reduce noise from roll former shears three noise abatement enclosures of different designs and sheet d ers were assessed. Results indicate that only a noise reduction of 5dB can be achieved at the operator position by noise abatement enclosures, virtually independent of their designs and materials. This rather poor performance of enclosures is basically caused by structure-borne paths whereby vibrations are transmitted through the metal sheet product itself from the inside of the enclosure to the outside. Sheet d ers which have been designed to reduce the impact induced vibrations of the sheet product achieves a similar noise reduction as the enclosures but at about one quarter of the cost.
Aerodynamic damping of randomly excited plates in stationary and moving air
Publisher: Elsevier BV
Date: 06-2003
An immersed boundary method for fluid–structure–acoustics interactions involving large deformations and complex geometries
Publisher: Elsevier BV
Date: 05-2020
Numerical simulation of transient response of heat transfer from a hot-wire anemometer transducer
Publisher: Elsevier BV
Date: 03-1985
Aerodynamic characteristics of hoverflies during hovering flight
Publisher: Elsevier BV
Date: 04-2019
Numerical Analysis of an Oscillating-Wing Wind and Hydropower Generator
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 07-2011
DOI: 10.2514/1.J050577
Brake squeal: A literature review
Publisher: Elsevier BV
Date: 04-2002
Rotational aerophones
Publisher: Acoustical Society of America (ASA)
Date: 03-2002
DOI: 10.1121/1.1446053
Abstract: Free rotational aerophones such as the bullroarer, which consists of a wooden slat whirled around on the end of a string, and which emits a loud pulsating roar, have been used in many ancient and traditional societies for ceremonial purposes. This article presents an experimental and theoretical investigation of this instrument. The aerodynamics of rotational behavior is elucidated, and relates slat rotation frequency to slat width and velocity through the air. Analysis shows that sound production is due to generation of an oscillating-rotating dipole across the slat, the role of the vortices shed by the slat being relatively minor. Apparent discrepancies between the behavior of a bullroarer slat and a slat mounted on an axle in a wind tunnel are shown to be due to viscous friction in the bearings of the wind-tunnel experiment.
Modelling the vibration behaviour of infinite structures by FEM
Publisher: Elsevier BV
Date: 2000
The sound radiation efficiency of finite length acoustically thick circular cylindrical shells under mechanical excitation I: Theoretical analysis
Publisher: Elsevier BV
Date: 04-2000
A new modified low-Reynolds-number k-ϵ model
Publisher: American Institute of Aeronautics and Astronautics
Date: 15-06-1998
DOI: 10.2514/6.1998-2553
Termites assess wood size by using vibration signals
Publisher: Proceedings of the National Academy of Sciences
Date: 25-02-2005
Abstract: Contrary to the common perception that termites are indiscriminant eaters, termites choose their food carefully however, the methods by which they choose food are not well understood. Using choice experiments and recordings of termites feeding on wooden blocks of different sizes, we show that worker drywood termites ( Cryptotermes domesticus ) use the resonant frequency of a block of wood to assess its size. Drywood termites showed differences in their response to vibration recordings of termites compared with artificially generated signals, suggesting that they can discriminate the source of vibration. Furthermore, fewer workers matured into neotenic reproductives when recorded termite signals were played, suggesting that vibration signals play an important role in termite communication.
Application of the sound intensity technique to measurement of field sound transmission loss
Publisher: Elsevier BV
Date: 1991
Effects of orthodontic therapy on the facial profile in long and short vertical facial patterns
Publisher: Elsevier BV
Date: 11-2000
Abstract: The purpose of the present study was to evaluate the effects of orthodontic treatment on the soft tissue facial profile of patients with long and short facial types. Orthodontic treatment records of 99 white long-faced and short-faced patients were analyzed to determine the effects of edgewise orthodontic treatment over an average period of 2.16 +/- 0.32 years. The average ages at the initiation and conclusion of treatment were 13.40 +/- 0.40 years and 15.61 +/- 0.29 years, respectively. A significant finding in this study was the large variability in soft tissue response to tooth movement. This variability was due to a wide dispersion of in idual results between upper and lower lip change to maxillary and mandibular incisor movement anteriorly or posteriorly. Because of this soft tissue variability among in iduals, definite differences between the long-faced and short-faced types could not be identified, nor was it possible to establish definite ratios for change in lip response to incisor movements.
Dynamic characteristics of a deformable capsule in a simple shear flow
Publisher: American Physical Society (APS)
Date: 07-02-2019
On the potential of uncertainty analysis for prediction of brake squeal propensity
Publisher: Elsevier BV
Date: 09-2016
A non-linear friction work formulation for the analysis of self-excited vibrations
Publisher: Elsevier BV
Date: 03-2019
Acoustic noise of electromagnetic origin in an ideal frequency-converter-driven induction motor
Publisher: Institution of Engineering and Technology (IET)
Date: 1994
Oscillation Frequency and Amplitude Effects on Plunging Airfoil Propulsion and Flow Periodicity
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 11-2012
DOI: 10.2514/1.J051374
Squeal noise in simple numerical brake models
Publisher: Elsevier BV
Date: 09-2015
Transition to chaos in a two-sided collapsible channel flow
Publisher: Cambridge University Press (CUP)
Date: 07-09-2021
DOI: 10.1017/JFM.2021.710
Abstract: The nonlinear dynamics of a two-sided collapsible channel flow is investigated by using an immersed boundary-lattice Boltzmann method. The stability of the hydrodynamic flow and collapsible channel walls is examined over a wide range of Reynolds numbers $Re$ , structure-to-fluid mass ratios $M$ and external pressures $P_e$ . Based on extensive simulations, we first characterise the chaotic behaviours of the collapsible channel flow and explore possible routes to chaos. We then explore the physical mechanisms responsible for the onset of self-excited oscillations. Nonlinear and rich dynamic behaviours of the collapsible system are discovered. Specifically, the system experiences a supercritical Hopf bifurcation leading to a period-1 limit cycle oscillation. The existence of chaotic behaviours of the collapsible channel walls is confirmed by a positive dominant Lyapunov exponent and a chaotic attractor in the velocity-displacement phase portrait of the mid-point of the collapsible channel wall. Chaos in the system can be reached via period-doubling and quasi-periodic bifurcations. It is also found that symmetry breaking is not a prerequisite for the onset of self-excited oscillations. However, symmetry breaking induced by mass ratio and external pressure may lead to a chaotic state. Unbalanced transmural pressure, wall inertia and shear layer instabilities in the vorticity waves contribute to the onset of self-excited oscillations of the collapsible system. The period-doubling, quasi-periodic and chaotic oscillations are closely associated with vortex pairing and merging of adjacent vortices, and interactions between the vortices on the upper and lower walls downstream of the throat.
Flapping foil power generator performance enhanced with a spring-connected tail
Publisher: AIP Publishing
Date: 12-2017
DOI: 10.1063/1.4998202
Abstract: The flexibility effects on the performance of a flapping foil power generator are numerically studied by using the immersed boundary-lattice Boltzmann method at a Reynolds number of 1100. The flapping foil system consists of a rigid NACA0015 foil undergoing harmonic pitch and plunge motions and a passively actuated flat plate pinned to the trailing edge of the rigid foil. The flexibility is modeled by a torsional spring model at the conjuncture of the rigid foil and the tail. Here, a parametric study on mass density and natural frequency is conducted under the optimum kinematic condition of the rigid system identified from the literature and numerical simulations made for reduced frequency f* = 0.04–0.24 and pitch litude θ0 = 40°–90°. Four typical cases are discussed in detail by considering time histories of hydrodynamic loads and tail deformations under the optimal and non-optimal kinematic conditions. Results show that under the rigid-system optimal kinematic condition, a tail with appropriate mass density (μ = 0.60) and resonant frequency ( fr*=1.18) can improve the maximum efficiency by 7.24% accompanied by an increase of 6.63% in power compared to those of a rigid foil with a rigid tail. This is because the deflection of the tail reduces the low pressure region on the pressure surface (i.e., the lower surface during the upstroke or the upper surface during the downstroke) caused by the leading edge vortex after the stroke reversal, resulting in a higher efficiency. At high flapping frequencies, a spring-connected tail ( fr*=0.13) eliminates the large spike in the moment observed in high stiffness cases, reducing the power required for the pitch motion, resulting in 117% improvement in efficiency over that with a rigid tail at a reduced frequency of 0.24.
Sound power radiated from an inverter-driven induction motor: Experimental investigation
Publisher: Institution of Engineering and Technology (IET)
Date: 2002
Flow Structures Around an Oscillating-Wing Power Generator
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 11-2015
DOI: 10.2514/1.J053950
Turbulence wavenumber spectra in fully-developed smooth pipe flow
Publisher: Springer Science and Business Media LLC
Date: 04-1992
DOI: 10.1007/BF00193883
Simulation and Parameter Variation of Flapping-Wing Motion Based on Dragonfly Hovering
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 04-2008
DOI: 10.2514/1.31610
Prediction of the effects on dynamic response due to distributed structural modification with additional degrees of freedom
Publisher: Elsevier BV
Date: 11-2008
Flapping Wing Aerodynamics: Progress and Challenges
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 09-2008
DOI: 10.2514/1.29263
Enhancing the Power-Extraction Efficiency of a Flapping Foil by Active Morphing
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 09-2023
DOI: 10.2514/1.J062291
Abstract: A computational study of two morphing, power-extracting flapping foils (a NACA 0015 at [Formula: see text] and a flat plate at [Formula: see text]) is conducted by considering three strategies: morphing of the leading edge (LE) or trailing edge (TE) alone, and morphing of both LE and TE simultaneously. The morphing variables are the phase shift and frequency of the edge deformation. All cases take into account the power required to morph the foils. The independently morphing LE/TE edge cases show regions of phase angle and frequency that yield improved efficiency over the rigid baseline of up to 16.8% for the NACA 0015 foil and 22.6% in the flat-plate case. The combined LE and TE cases further increase the efficiency, up to 29.7% for the NACA 0015 foil and 36.2% in the flat-plate case. Three physical mechanisms are identified that lead to efficiency increases in the various cases through the interaction between the morphing foil and shed vortex structure. These are the change in projected area during the plunging stroke, the variation of leading-edge vortex shedding timing during the cycle, and the proximity of the shed vortex structure to the foil during the pitching portion of the stroke.
Quantifying Ant Activity Using Vibration Measurements
Publisher: Public Library of Science (PLoS)
Date: 21-03-2014
Novel Method for Pairing Wood Samples in Choice Tests
Publisher: Public Library of Science (PLoS)
Date: 14-02-2014
Dynamic Behaviours of a Filament in a Viscoelastic Uniform Flow
Publisher: MDPI AG
Date: 22-02-2021
Abstract: The dynamic behaviours of a filament in a viscoelastic uniform flow were investigated by an immersed boundary-lattice Boltzmann method. The effects of the Reynolds numbers (Re, ranging from 10 to 200) and the Weissenberg number (Wi, ranging from 0 to 1.2) on the filament flapping motion and the drag and lift coefficients on the filament were studied. It was found that a higher inertial effect (larger Re) promotes the flapping motion of the filament. In addition, the major effect of the viscoelasticity of the Giesekus fluid is to decrease the critical Reynolds number for the flapping motion of the filament and to promote the flapping motion. The drag coefficient on the filament in a Giesekus uniform flow decreases with the increase of Wi at low Re (Re ), and experiences oscillations with similar litudes at all Wi at a sufficiently high Re (Re ). In contrast, the viscoelasticity of the FENE-CR fluid increases the critical Reynolds number at lower Wi (Wi .8), and shows little influence on the critical Reynolds number at higher Wi (Wi≥0.8). In addition, the viscoelasticity of the FENE-CR fluid hinders the flapping motion of the filament, and increases the drag coefficient on the filament at low Re (Re ).
Comments on vibration analysis of thin cylindrical shells using the wave propagation approach
Publisher: Elsevier BV
Date: 2003
Jet excitation by an oscillating vane
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 06-1981
DOI: 10.2514/3.7810
An extended macroscopic model for solute dispersion in confined porous media
Publisher: Elsevier BV
Date: 15-04-2008
Mechanisms Influencing the Efficiency of Oscillating Airfoil Propulsion
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 07-2007
DOI: 10.2514/1.27628
Chaos in brake squeal noise
Publisher: Elsevier BV
Date: 02-2011
Unsteady effects in mechanically-excited turbulent plane jets
Publisher: Elsevier BV
Date: 12-1984
Vibration power transmission over a rectangular area of an infinite plate subject to uniform conphase velocity excitation
Publisher: Elsevier BV
Date: 10-2002
A review of progress and challenges in flapping foil power generation
Publisher: Elsevier BV
Date: 05-2014
Streamline penetration, velocity error, and consequences of the feedback immersed boundary method
Publisher: AIP Publishing
Date: 09-2022
DOI: 10.1063/5.0101584
Abstract: This paper presents a study on streamline penetration, velocity error, and consequences of a fluid–structure interaction (FSI) solver based on the feedback immersed boundary method (IBM). In the FSI solver, the fluid dynamics is solved by the lattice Boltzmann method the solid structure deformation is solved by the finite difference method and the finite element method for two- and three-dimensional cases, respectively and the feedback IBM is used to realize the interaction between the fluid and the structure. The IBM is implemented in non-iterative and iterative ways. For the non-iterative version, two types of integration are discussed: without and with velocity prediction step. Five benchmark cases are simulated to study the performance of the three implementations: a uniform flow over a cylinder, flow-induced vibration of a flexible plate attached behind a stationary cylinder in a channel, flow through a two-dimensional asymmetric stenosis, a one-sided collapsible channel, and a three-dimensional collapsible tube. Results show that both the IBM with prediction step, the iterative IBM, and one iteration IBM with proper feedback coefficients can suppress the spurious flow penetration on the solid wall. While the velocity error does not significantly affect the force production and structure deformation for external flows, reducing it significantly improves the prediction of the force distribution and structure deformation for internal flows. In addition, the iterative IBM with smaller feedback coefficient has better numerical stability. This work will provide an important guideline for the correct use of the feedback IBMs.
Error considerations for turbulence measurements using laser-two-focus velocimetry
Publisher: IOP Publishing
Date: 02-1989
Sound power radiated from an inverter driven induction motor II: Numerical analysis
Publisher: Institution of Engineering and Technology (IET)
Date: 2004
Control of backward-facing step flow using a flapping foil
Publisher: Springer Science and Business Media LLC
Date: 2002
Instability analysis of friction oscillators with uncertainty in the friction law distribution
Publisher: SAGE Publications
Date: 19-11-2015
Abstract: Despite substantial research efforts in the past two decades, the prediction of brake squeal propensity, as a significant noise, vibration and harshness (NVH) issue to automotive manufactures, is as difficult as ever. This is due to the complexity of the interacting mechanisms (e.g. stick-slip, sprag-slip, mode coupling and hammering effect) and the uncertain operating conditions (temperature, pressure). In particular, two major aspects in brake squeal have attracted significant attention recently: nonlinearity and uncertainty. The fugitiveness of brake squeal could be attributed to a number of factors including the difficulty in accurately modelling friction. In this paper, the influence of the uncertainty arising from the tribological aspect in brake squeal prediction is analysed. Three types of friction models, namely the Amonton-Coulomb model, the velocity-dependent model and the LuGre model, are randomly assigned to a group of interconnected oscillators which model the dynamics of a brake system. The complex eigenvalue analysis, as a standard stability analysis tool, and the friction work calculation are performed to investigate the probability for instability arising from the uncertainty in the friction models. The results are discussed with a view to apply this approach to the analysis of the squeal propensity for a full brake system.
Kinematic optimization of a flapping foil power generator using a multi-fidelity evolutionary algorithm
Publisher: Elsevier BV
Date: 03-2019
Improving power-extraction efficiency of a flapping plate: From passive deformation to active control
Publisher: Elsevier BV
Date: 11-2014
Application of the sound intensity technique to noise source identification: A case study
Publisher: Elsevier BV
Date: 1991
The preferred mode of a tube jet
Publisher: Elsevier BV
Date: 09-1991
The role of flow characteristics in corrosion-erosion of tube inlets in the inlet channel of shell and tube heat exchangers
Publisher: Elsevier BV
Date: 05-1979
An FSI solution technique based on the DSD/SST method and its applications
Publisher: World Scientific Pub Co Pte Lt
Date: 24-08-2015
DOI: 10.1142/S0218202515400084
Abstract: This paper presents a fluid–structure interaction (FSI) solution technique in which the incompressible fluid dynamics involving moving boundaries is solved with the deforming-spatial-domain/stabilized space–time (DSD/SST) method and the structural dynamics is solved with the finite difference (FD) method. The DSD/SST and FD solvers are coupled by an implicit partitioned coupling strategy based on staggered subiterations. Three types of relaxation are applied on the FSI surface velocity and hydrodynamic force. The first one is applied to delay the coupling conditions at the beginning of each simulation the second one is applied to relax the increment during each subiteration and the third one is applied to filter high frequency oscillations between each time step. A pitching plate in a uniform flow is calculated to validate the FSI technique. The present results are in good agreement with data predicted by other methods. In addition, two problems are calculated to demonstrate the capability of this solver: an orbital flow over flapping foil propulsion and energy harvesting and a flexible plate in a cavity excited by an external force.
Numerical solution of periodically pulsed laminar free jets
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 06-1981
DOI: 10.2514/3.7820
Effects of distributed structural dynamic modification with reduced degrees of freedom
Publisher: Elsevier BV
Date: 10-2009
Effects of wing flexibility on bumblebee propulsion
Publisher: Elsevier BV
Date: 2017
Renewable Hydrogen Production Using Sailing Ships
Publisher: ASME International
Date: 20-02-2014
DOI: 10.1115/1.4026200
Abstract: Vast ocean areas of planet Earth are exposed year-round to strong wind currents. We suggest that this untapped ocean wind power be exploited by the use of sailing ships. The availability of constantly updated meteorological information makes it possible to operate the ships in ocean areas with optimum wind power so that the propulsive ship power can be converted into electric power by means of ship-mounted hydro-power generators. Their electric power output then is fed into ship-mounted electrolyzers to convert sea water into hydrogen and oxygen. In this paper, we estimate the ship size, sail area, and generator size to produce a 1.5 MW electrical power output. We describe a new oscillating-wing hydro-power generator and present results of model tests obtained in a towing tank. Navier-Stokes computations are presented to provide an estimate of the power extraction efficiency and drag coefficient of such a generator which depends on a range of parameters such as foil maximum pitch angles, plunge litude, phase between pitch and plunge and load. Also, we present a discussion of the feasibility of sea water electrolysis and of the reconversion of hydrogen and oxygen into electricity by means of shore-based hydrogen-oxygen power plants.
Oscillating reed valves - An experimental study
Publisher: Acoustical Society of America (ASA)
Date: 07-2000
DOI: 10.1121/1.429473
Abstract: The results of experiments on the threshold behavior and large- litude oscillation of “outward-swinging door” vibrating flap valves in an air environment are reported and compared with the predictions of a simple nonlinear theory that parametrizes aerodynamic effects by means of a simple d ing coefficient together with a contraction coefficient for the flow. The agreement is acceptably good for the threshold blowing pressure for valve oscillation, the large-signal vibration litude, the pressure jump in the transition from threshold to large-signal behavior, and the variation in vibration frequency, all as functions of reservoir volume. The calculated pressure waveform in the reservoir has the observed phase and magnitude but fails to reproduce finer details. It is concluded that the simple theory provides an adequate account of the behavior of such valves. There are just two parameters in the theory, describing jet contraction and aerodynamic d ing, respectively. Since these may depend significantly upon the detailed geometry, valves with different shapes may behave in quantitatively different ways.
Analytical Prediction of Noise of Magnetic Origin Produced by Permanent Magnet Brushless Motors
Publisher: IEEE
Date: 05-2007
Effects of wing shape, aspect ratio and deviation angle on aerodynamic performance of flapping wings in hover
Publisher: AIP Publishing
Date: 11-2016
DOI: 10.1063/1.4964928
Abstract: This numerical study is focused on assessing the effect on the aerodynamic hovering performance of wing shapes defined by the radius of the first moment of the wing area (r1¯) and aspect ratio (AR). In addition, the effect of introducing a deviation angle in the kinematics is examined. The performance of r1¯=0.43, 0.53, and 0.63 wings with AR of 1.5, 2.96, 4.5, and 6.0 is investigated at Reynolds numbers (Re) = 12, 400, and 13 500. The performance trends of the wing shapes have been observed to be independent of Re for both 2-angle and 3-angle kinematics. This is because high suction pressures associated with the leading-edge vortex are predominantly spread in the distal (away from the wing root) and leeward regions (towards the trailing-edge) of high flapping velocities for all the cases. While the deviation angle is detrimental to the production of lift and power economy (PE, defined as the ratio of the mean lift coefficient to the mean aerodynamic power coefficient) at Re = 12 due to strong viscous effects, it improves PE at Re = 400 and 13 500. A high instantaneous angle of attack at the stroke reversal results in high lift peak for 3-angle kinematics but its effect at Re = 400 and 13 500 is attenuated by strong vortical structures on the underside of the wing. Maximum PE is achieved at AR = 2.96, as a low AR wing does not produce enough lift and high AR wings consume more aerodynamic power. Although the lift is maximized using high r1¯ and AR wings, our results show that low r1¯ and high AR wings are best for maximizing PE for a given lift in insects.
An Innovative Signal Processing Method to Extract Ants’ Walking Signals
Publisher: Springer Science and Business Media LLC
Date: 18-03-2015
Sound power radiated from an inverter-driven induction motor. Part 3: Statistical energy analysis
Publisher: Institution of Engineering and Technology (IET)
Date: 2005
Nonlinear transient and chaotic interactions in disc brake squeal
Publisher: Elsevier BV
Date: 04-2015
VISUALIZING VORTEX FORMATION IN THE WAKES OF TURBINE BLADES AND OSCILLATING AEROFOILS
Publisher: Begell House
Date: 2007
Discussions on on the number of modes required for statistical energy analysis-based calculations
Publisher: Elsevier BV
Date: 03-2005
ARMAX modal parameter identification in the presence of unmeasured excitation-I: Theoretical background
Publisher: Elsevier BV
Date: 05-2007
ARMAX modal parameter identification in the presence of unmeasured excitation-II: Numerical and experimental verification
Publisher: Elsevier BV
Date: 05-2007
Effects of hawkmoth-like flexibility on the aerodynamic performance of flapping wings with different shapes and aspect ratios
Publisher: AIP Publishing
Date: 09-2018
DOI: 10.1063/1.5044635
Abstract: The effect of hawkmoth-like flexibility on the aerodynamic hovering performance of wings at a Reynolds number of 400 has been assessed by conducting fluid structure interaction simulations incorporating a finite difference based immersed boundary method coupled with a finite-element based structure solver. The stiffness distribution of a hawkmoth forewing was mapped onto three wing shapes (r¯1 = 0.43, 0.53, and 0.63) defined by the radius of the first moment of wing area each with aspect ratios, AR = 1.5, 2.96, 4.5, and 6.0 using elliptic mesh generation, the Jacobi method for iterations, and the concept of the barycentric coordinate system. The results show that there is a dominant chordwise deformation at AR = 1.5, and the wings also deform in the spanwise direction and their tips deviate from the horizontal stroke plane as AR increases. At AR = 1.5, 2.96, and 4.5, flexibility increases the mean lift (up to 39%, 18%, and 17.6%, respectively) for all wing shapes. At AR = 6.0, the r1¯ = 0.53 and 0.63 flexible wings give lesser lift than the rigid equivalents because of negative lift or small positive lift during the early stroke as the vortical structures remain on the bottom surface. This is attributed to the rapid pitch-down rotation, lesser stroke angular velocity than the rigid wing, and upward motion of the wingtip, away from the horizontal stroke plane. From the design perspective, the anisotropic flexible wings (except r1¯ = 0.53 and 0.63 with AR = 6.0) can be used in micro aerial vehicles for high lift requirements, such as for a high payload. Results here show that in nature, the hawkmoth wings with r1¯ and AR of 0.43-0.44 and 2.73-2.92, respectively, appear to have a combination of the shape, AR, and flexibility that optimizes power economy.
Investigation of Oscillating-Foil Power Generation in Constrained Flow
Publisher: Elsevier BV
Date: 2017
The Role of Nonlinearity and Uncertainty in Assessing Disc Brake Squeal Propensity
Publisher: SAE International
Date: 15-06-2016
DOI: 10.4271/2016-01-1777
Energy harvesting of inverted piezoelectric flags in an oscillating flow
Publisher: Elsevier BV
Date: 11-2022
Experimental measurement of surface mobility over a rectangular contact area subject to a uniform conphase velocity excitation
Publisher: Elsevier BV
Date: 07-2001
Optimal Efficiency and Heaving Velocity in Flapping Foil Propulsion
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 06-2021
DOI: 10.2514/1.J059866
Revisiting stigmergy in light of multi-functional, biogenic, termite structures as communication channel
Publisher: Elsevier BV
Date: 2020
Discrete Vortex Method with Flow Separation Corrections for Flapping-Foil Power Generators
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 02-2017
DOI: 10.2514/1.J055267
Reynolds number, thickness and camber effects on flapping airfoil propulsion
Publisher: Elsevier BV
Date: 02-2011
The influence of nonuniform coating and taylor dispersion on the evaluation of capillary column inverse gas chromatography
Publisher: Elsevier BV
Date: 10-2005
DOI: 10.1016/J.CHROMA.2005.07.043
Abstract: A mathematical model which takes into account the combined effect of Taylor dispersion and film eccentricity on the elution profiles has been developed for the analysis of a capillary column inverse gas chromatography (CCIGC) experiment. In this paper, we present an additional improvement on the model presented by Hamdan et al. [E. Hamdan, J. F. Milthorpe, J. C. S. Lai, J. Chromatogr. A, 1078 (2005) 144] to include the effect of coating nonuniformity. The new model shows that while Taylor dispersion effect has a very significant effect on the elution profiles at low values of beta and gamma, the general effect of film asymmetry is to reduce this effect. At sufficiently large gamma and/or beta values, Taylor dispersion effect becomes negligible and the elution profiles will be mainly affected by film asymmetry. The inclusion of Taylor dispersion effect will increase the variance of the elution curves which could significantly affect the estimated value of the diffusivity Dp. The error in the estimated Dp values obtained using the Pawlisch et al. [C. A. Pawlisch, J. R. Bric, R.L. Laurence, Macromolecules 21 (1988) 1685] nonuniform model increases as gamma and/or beta are reduced and when the coated polymer exhibits less deviation from uniform films.
Foraging vibration signals attract foragers and identify food size in the drywood termite, Cryptotermes secundus
Publisher: Springer Science and Business Media LLC
Date: 18-09-2007
Effects of distributed structural dynamic modification with additional degrees of freedom on 3D structure
Publisher: Elsevier BV
Date: 07-2010
Control of corrosion-erosion of tube inlets of shell and tube heat exchangers
Publisher: Elsevier BV
Date: 05-1979
Instantaneous velocity measurements in a vane-excited plane jet
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 08-1985
DOI: 10.2514/3.9058
Prediction of acoustic noise from variable-speed induction motors: Deterministic versus statistical approaches
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2002
Cryptic termites avoid predatory ants by eavesdropping on vibrational cues from their footsteps.
Publisher: Wiley
Date: 23-01-2017
DOI: 10.1111/ELE.12727
Abstract: Eavesdropping has evolved in many predator-prey relationships. Communication signals of social species may be particularly vulnerable to eavesdropping, such as pheromones produced by ants, which are predators of termites. Termites communicate mostly by way of substrate-borne vibrations, which suggest they may be able to eavesdrop, using two possible mechanisms: ant chemicals or ant vibrations. We observed termites foraging within millimetres of ants in the field, suggesting the evolution of specialised detection behaviours. We found the termite Coptotermes acinaciformis detected their major predator, the ant Iridomyrmex purpureus, through thin wood using only vibrational cues from walking, and not chemical signals. Comparison of 16 termite and ant species found the ants-walking signals were up to 100 times higher than those of termites. Eavesdropping on passive walking signals explains the predator detection and foraging behaviours in this ancient relationship, which may be applicable to many other predator-prey relationships.
Mass spectrometric determination of nitrogen oxides in turbocharged diesel engine exhaust
Publisher: SAE International
Date: 02-1983
DOI: 10.4271/830454
Termites live in a material world: exploration of their ability to differentiate between food sources
Publisher: The Royal Society
Date: 13-03-2007
Abstract: Drywood termites are able to assess wood size using vibratory signals, although the exact mechanism behind this assessment ability is not known. Important vibratory characteristics such as the modal frequencies of a wooden block depend on its geometry and boundary conditions however, they are also dependent on the material characteristics of the block, such as mass, density and internal d ing. We report here on choice experiments that tested the ability of the drywood termite Cryptotermes secundus to assess wooden block size using a solid wooden block paired with a composite block, the latter made of either wood and aluminium or wood and rubber. Each composite block was constructed to match mass or low-frequency vibratory modes (i.e. fundamental frequency) of the solid wooden block. The termites always chose the blocks with more wood they moved to the solid wooden blocks usually within a day and then tunnelled further into the solid wooden block by the end of the experiment. Termites offered composite blocks of wood and rubber matched for mass were the slowest to show a preference for the solid wooden block and this preference was the least definitive of any treatment, which indicated that mass and/or d ing may play a role in food assessment. This result clearly shows that the termites were not fooled by composite blocks matched for mass or frequency, which implies that they probably employ more than a single simple measure in their food assessment strategy. This implies a degree of sophistication in their ability to assess their environment hitherto unknown. The potential importance of alternative features in the vibrational signals is discussed.
Coupling performance of two tandem and side-by-side inverted piezoelectric flags in an oscillating flow
Publisher: Elsevier BV
Date: 05-2023
Vibro-acoustic and nonlinear analysis of cadavric femoral bone impaction in cavity preparations
Publisher: EDP Sciences
Date: 2018
DOI: 10.1051/MATECCONF/201814814007
Abstract: Owing to an ageing population, the impact of unhealthy lifestyle, or simply congenital or gender specific issues (dysplasia), degenerative bone and joint disease (osteoarthritis) at the hip pose an increasing problem in many countries. Osteoarthritis is painful and causes mobility restrictions amelioration is often only achieved by replacing the complete hip joint in a total hip arthroplasty (THA). Despite significant orthopaedic progress related to THA, the success of the surgical process relies heavily on the judgement, experience, skills and techniques used of the surgeon. One common way of implanting the stem into the femur is press fitting uncemented stem designs into a prepared cavity. By using a range of compaction broaches, which are impacted into the femur, the cavity for the implant is formed. However, the surgeon decides whether to change the size of the broach, how hard and fast it is impacted or when to stop the excavation process, merely based on acoustic, haptic or visual cues which are subjective. It is known that non-ideal cavity preparations increase the risk of peri-prosthetic fractures especially in elderly people. This study reports on a simulated hip replacement surgery on a cadaver and the analysis of impaction forces and the microphone signals during compaction. The recorded transient signals of impaction forces and acoustic pressures (≈ 80 μ s - 2 ms) are statistically analysed for their trend, which shows increasing heteroscedasticity in the force-pressure relationship between broach sizes. T ikhonov regularisation, as inverse deconvolution technique, is applied to calculate the acoustic transfer functions from the acoustic responses and their mechanical impacts. The extracted spectra highlight that system characteristics altered during the cavity preparation process: in the high-frequency range the number of resonances increased with impacts and broach size. By applying nonlinear time series analysis the system dynamics increase in complexity and demand for a larger minimum embedding dimension. The growing number of resonances with similar level of the transfer function indicates a higher propensity to dissipate energy over sound the change in embedding dimension indicates a decrease in linearity. The spectral changes as well as the altered dimension requirements indicate either an improved coupling between the bone and the broach or the onset of micro-fractures caused by growing stress levels within the bone.
A statistical approach to estimate the Lyapunov spectrum in disc brake squeal
Publisher: Elsevier BV
Date: 2015
Energy harvesting of two inverted piezoelectric flags in tandem, side-by-side and staggered arrangements
Publisher: Elsevier BV
Date: 06-2020
Numerical Simulation of Fully Passive Flapping Foil Power Generation
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 11-2013
DOI: 10.2514/1.J052542
Sound transmission loss measurements using the sound intensity technique Part 1: The effects of reverberation time
Publisher: Elsevier BV
Date: 1993
Flow around an Oscillating Tandem-Wing Power Generator
Publisher: American Institute of Aeronautics and Astronautics
Date: 03-01-2015
DOI: 10.2514/6.2015-1751
New approach for evaluation of capillary column inverse gas chromatography
Publisher: Elsevier BV
Date: 06-2005
DOI: 10.1016/J.CHROMA.2005.05.021
Abstract: A mathematical model has been developed for the analysis of a capillary column IGC experiment. An important feature in the derivation of the model is the inclusion of Taylor dispersion effect. The model shows that Taylor dispersion effect has a very significant effect on elution profiles at low values of beta and gamma. Taylor dispersion effect causes more spread in the longitudinal direction and the peaks become broader. Taylor dispersion becomes more significant as beta becomes smaller. The model presented in this paper is more general than the usual IGC models and sets criteria equations to determine under what conditions the Taylor dispersion effect can be made negligible. A comparison between the present and usual IGC models above and near the glass temperature of the polymer is conducted. The analysis also describes the effect of kurtosis on pulse dispersion at extremely low diffusivities.
Acoustic noise prediction in a vector controlled induction machine
Publisher: IEEE
Date: 2003
Influences of serrated trailing edge on the aerodynamic and aeroacoustic performance of a flapping wing during hovering flight
Publisher: AIP Publishing
Date: 2022
DOI: 10.1063/5.0070450
Abstract: The influences of serrated trailing edge on the aerodynamic and aeroacoustic performance of a flapping wing during hovering flight are investigated using a hybrid framework of an immersed boundary Navier–Stokes solver for the flow field and the Ffowcs Williams–Hawkings (FW–H) analogy for the sound field. A rigid rectangular wing with an aspect ratio of 2 undergoes pitching and stroke motions at a Reynolds number (Re) of 310 and a Mach number (M) of 0.012. Simulations are conducted by varying the dimensionless wavenumber k* from 2π to 10π and wave litude 2h* from 0.25 to 1.0. We find that at k*=8π and 2h*=1.5 (D4), the average sound power level is reduced by up to 6.8 dB within the Strouhal number (St) between 2.0 and 4.0 compared to that of a plain trailing edge while the lift coefficient is maintained. The directivity at St = 0.2, St = 0.4, St = 2.2, and St = 2.4 is discussed. It is found that the serrations of D4 do not affect the directivity for the first two frequencies and significantly reduce the magnitude of the directivity for the last two frequencies. The serrations of D4 considerably alter the flow field near the wing surface and reduced the surface pressure fluctuations near the wing tip, leading to the noise reduction. The lift coefficient of D4 is not significantly changed, because the reduction in the pressure-contributed lift is compensated by an increase in the shear stress-contributed lift. The serrations with higher 2h* and k* have larger shear stress-contributed lift.
Termites eavesdrop to avoid competitors
Publisher: The Royal Society
Date: 26-08-2009
Abstract: Competition exclusion, when a single species dominates resources due to superior competitiveness, is seldom observed in nature. Termites compete for resources with deadly consequences, yet more than one species can be found feeding in the same wooden resource. This is especially surprising when drywood species, with colonies of a few hundred, are found cohabiting with subterranean species, with colonies of millions. Termites communicate vibro-acoustically and, as these signals can travel over long distances, they are vulnerable to eavesdropping. We investigated whether drywood termites could eavesdrop on vibration cues from subterranean species. We show, using choice experiments and recordings, that the drywood termite Cryptotermes secundus can distinguish its own species from the dominant competitor in the environment, the subterranean termite Coptotermes acinaciformis . The drywood termite was attracted to its own vibration cues, but was repelled by those of the subterranean species. This response increased with decreasing wood size, corresponding with both increased risk and strength of the cue. The drywood termites appear to avoid confrontation by eavesdropping on the subterranean termites these results provide further evidence that vibro-acoustic cues are important for termite sensory perception and communication.
Modelling termites’ tunnelling and decision-making behaviors
Publisher: Cold Spring Harbor Laboratory
Date: 08-10-2023
Termites manipulate moisture content of wood to maximize foraging resources
Publisher: The Royal Society
Date: 07-2019
Abstract: Animals use cues to find their food, in microhabitats within their physiological tolerances. Termites build and modify their microhabitat, to transform hostile environments into benign ones, which raises questions about the relative importance of cues. Termites are desiccation intolerant and foraging termites are attracted to water, so most research has considered moisture to be a cue. However, termites can also transport water to food, and so moisture may play other roles than previously considered. To examine the role of moisture, we compared Coptotermes acinaciformis termite foraging decisions in laboratory experiments when they were offered dry and moist wood, with and without load. Without load, termites preferred moist wood and ate it without any building, whereas they moistened dry wood after wrapping it in a layer of clay. For the ‘With load’ units, termites substituted some of the wood for load-bearing clay walls, and kept the wood drier than on the unloaded units. As drier wood has higher compressive strength and higher rigidity, it allows more of the wood to be consumed. These results suggest that moisture plays a more important role in termite ecology than previously thought. Termites manipulate the moisture content according to the situational context and use it for multiple purposes: increased moisture levels soften the fibre, which facilitates foraging, yet keeping the wood dry provides higher structural stability against buckling which is especially important when foraging on wood under load.
Termites utilise clay to build structural supports and so increase foraging resources
Publisher: Springer Science and Business Media LLC
Date: 08-02-2016
DOI: 10.1038/SREP20990
Abstract: Many termite species use clay to build foraging galleries and mound-nests. In some cases clay is placed within excavations of their wooden food, such as living trees or timber in buildings however the purpose for this clay is unclear. We tested the hypotheses that termites can identify load bearing wood and that they use clay to provide mechanical support of the load and thus allow them to eat the wood. In field and laboratory experiments, we show that the lower termite Coptotermes acinaciformis , the most basal species to build a mound-nest, can distinguish unloaded from loaded wood and use clay differently when eating each type. The termites target unloaded wood preferentially and use thin clay sheeting to camouflage themselves while eating the unloaded wood. The termites attack loaded wood secondarily and build thick, load-bearing clay walls when they do. The termites add clay and build thicker walls as the load-bearing wood is consumed. The use of clay to support wood under load unlocks otherwise unavailable food resources. This behaviour may represent an evolutionary step from foraging behaviour to nest building in lower termites.
Statistical analysis of brake squeal noise
Publisher: Elsevier BV
Date: 06-2011
Addendum to “A review of progress and challenges in flapping foil power generation” [Prog. Aerosp. Sci., in press]
Publisher: Elsevier BV
Date: 05-2014
Effect of wall inclination on the mean flow and turbulence characteristics in a two-dimensional wall jet
Publisher: Elsevier BV
Date: 08-1996
Flapping foil power generation: Review and potential in pico-hydro application
Publisher: IEEE
Date: 10-2015
Turbulence suppression in an elliptic jet
Publisher: Elsevier BV
Date: 03-1992
Effects of time-varying camber deformation on flapping foil propulsion and power extraction
Publisher: Elsevier BV
Date: 07-2015
Foraging choice and replacement reproductives facilitate invasiveness in drywood termites
Publisher: Springer Science and Business Media LLC
Date: 27-11-2011
Vortex Lock-In Phenomenon in the Wake of a Plunging Airfoil
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 02-2007
DOI: 10.2514/1.23594
Vibro-acoustic and nonlinear analysis of cadavric femoral bone impaction in cavity preparations
Publisher: Elsevier BV
Date: 08-2018
Pitch perturbation effects on a revolving wing at low Reynolds number
Publisher: American Physical Society (APS)
Date: 12-10-2023
Flow structures generated by pressure-controlled self-oscillating reed valves
Publisher: Elsevier BV
Date: 10-2001
The role of pad-modes and nonlinearity in instantaneous mode squeal
Publisher: ASA
Date: 2013
DOI: 10.1121/1.4800947
An immersed boundary-lattice Boltzmann method for fluid-structure interaction problems involving viscoelastic fluids and complex geometries
Publisher: Elsevier BV
Date: 08-2020
Radiation efficiency of acoustic guitars
Publisher: Acoustical Society of America (ASA)
Date: 09-1990
DOI: 10.1121/1.399699
Abstract: The transfer functions between acceleration and force (‘‘accelerance’’) at the driving point and radiation efficiencies for the top plates of guitars have been investigated. A vibration exciter was used for driving the guitar at the bridge and the transfer functions and cross-power spectra were measured at the driving point with the aid of an impedance head. The frequency spectrum of the accelerance function determined in this manner showed good agreement with those reported for the same guitar using a different excitation and measurement method. The output acoustic intensity was measured with a sound-intensity probe and the radiated sound power from the top plate was determined. The radiation efficiency, determined from the ratio of the top plate radiated sound power and the input power, is presented for different guitars and for a guitar with a modified top plate.
Instantaneous velocity measurements in a periodically pulsed plane turbulent jet
Publisher: American Institute of Aeronautics and Astronautics (AIAA)
Date: 12-1980
DOI: 10.2514/3.7740
Effects of flexibility on the hovering performance of flapping wings with different shapes and aspect ratios
Publisher: Elsevier BV
Date: 08-2018
Metal-Cutting Machinery Noise and Vibration Prediction and Control
Publisher: Wiley
Date: 19-09-2008
A novel geometry-adaptive Cartesian grid based immersed boundary–lattice Boltzmann method for fluid–structure interactions at moderate and high Reynolds numbers
Publisher: Elsevier BV
Date: 12-2018
The sound radiation efficiency of finite length circular cylindrical shells under mechanical excitation II: Limitations of the infinite length model
Publisher: Elsevier BV
Date: 04-2001
Effect of Vibratory Soldier Alarm Signals on the Foraging Behavior of Subterranean Termites (Isoptera Rhinotermitidae)
Publisher: Oxford University Press (OUP)
Date: 02-2009
DOI: 10.1603/029.102.0117
Abstract: Termite soldiers produce a vibratory alarm signal to warn conspecific workers. This study recorded and characterized the alarm signals of Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinotermitidae) and then investigated the effect of playing these recorded alarm signals on C. acinaciformis feeding activity. Foraging groups of termites were offered paired wooden blocks: either one block, continuously stimulated with a vibratory alarm signal, paired with a nonstimulated block (the alarm treatment), continuously stimulated with a pink noise signal, paired with a nonstimulated block (control for nonspecific vibrations) or two nonstimulated blocks (control for environmental effects), for 4 wk. The amount of wood eaten in the blocks stimulated by the alarm signals was significantly less than the paired nonstimulated blocks, while there seemed to be no preference in the case of the pink noise playback or control for direction. Importantly, the termites seemed not to have adapted to the recorded alarm signal over the 4-wk duration of the experiment, unlike previous studies using nonbiologically derived signals.
Analysis of unsteady flow effects on the Betz limit for flapping foil power generation
Publisher: Cambridge University Press (CUP)
Date: 14-09-2020
DOI: 10.1017/JFM.2020.612
A hydrostatic transmission for a load-haul-dump vehicle
Publisher: SAE International
Date: 09-1987
DOI: 10.4271/871599
Guidelines for numerical vibration and acoustic analysis of disc brake squeal using simple models of brake systems
Publisher: Elsevier BV
Date: 04-2013
Numerical study of rigid and flexible wing shapes in hover
Publisher: IOP Publishing
Date: 11-04-2017
Pad-mode-induced instantaneous mode instability for simple models of brake systems
Publisher: Elsevier BV
Date: 10-2015
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