7,497 research outputs found
Tim Waters
No full textFurman University Marching Band sousaphone player, Tim Waters, playing performing during a halftime show
Parameterised Spin Model For FePt
No full textDataset supporting: Waters, J. M. et. al. (2019). Resolving Anomalies in the Critical Exponents of FePt Using Finite-Size Scaling in Magnetic Fields. Physical Review Applied. DOI:10.1103/PhysRevApplied.11.024028
Interaction strengths between Fe atoms in a parameterised spin model of FePt in the L10 crystal structure.
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On the performance of a nonlinear vibration isolator consisting of axially loaded curved beams
No full textA desirable characteristic for nonlinear vibration isolators is a high static stiffness and a low dynamic stiffness. A curved beam is a possible candidate for this role provided that the amplitude of vibration about the static equilibrium position is sufficiently small. However, for large amplitude oscillations, the nonlinear dynamics may have a detrimental effect. This paper considers the force transmissibility of a single degree-of-freedom system where the stiffness element is a curved, axially loaded beam. The transmitted force is calculated by numerical time domain integration of the equations of motion. The exact force-deflection relation for the beam is used for the spring. By comparison, a frequency domain solution is sought using the Harmonic Balance (HB) method in which the system is modelled as a Duffing oscillator. It is shown that the HB and time domain solutions are in close agreement for small amplitudes of excitation and both predict advantageous performance of the nonlinear isolator compared with its equivalent linear counterpart. However, significant discrepancies occur between the two solutions for large excitation since the beam can no longer be approximated by a linear and a cubic stiffness. It is also strongly asymmetric – soft in compression but stiff in extreme extension– which gives rise to an impulse in the transmitted force in each fundamental period. This numerical problem is alleviated by inserting a linear spring in series with the beam isolator with a modest compromise in isolation performance at the excitation frequency
Do dolphins benefit from nonlinear mathematics when processing their sonar returns?
No full textAn interview with author Tim Leighton about the paper
Focussing acoustic waves with intent to control biofouling in water pipes
No full textThe colonisation of water pipes by macro-fouling organisms,such as barnacles and mussels, has presented a significant problem toindustries drawing water from infested sources. Some of these creatureshave been shown to be sensitive to low frequency sound and vibration,which have the potential to disrupt settlement and control populationgrowth without the need for chemical interventions. The applicability ofacoustic techniques to this problem is critically dependent on the achievablerange of guided waves in the fluid or pipe wall which attenuate withdistance from the actuation position due to mechanical losses.In this paper, fluid waves are considered owing to their typically lowerattenuation rates. A fluid-filled pipe is modelled analytically as a 2D rigidwalled duct. Higher order acoustic waves, which are dispersive immediatelyabove cut-on, are focussed at a target position using a transient excitation.The input waveform is obtained by filtering and time-reversingthe impulse response so as to compensate for dispersion thereby compressingthe signal in time and space. Simulations show that peak pressurescan be obtained that are more than an order of magnitude higherthan those achievable by harmonic excitation. Future work will modelfocussing of waves in a 3D pipe with fluid-structure coupling for whichexperimental validation will be sought
Opportunities for linking young surveyors across professional surveying member organisations and FIG
No full textTim Di Muzio on 'Sabotage'
No full textIn a series of essays published in 2013 and 2014 on capitaspower.com, political economist Tim Di Muzio explored the concept of ‘sabotage’ as it applies to capitalist power. I recently rediscovered these essays and was so impressed by them that I have reposted them here as a single piece.
About the author: Tim Di Muzio is a researcher at the University of Wollongong. He is the author of numerous books, including Debt as power, Carbon capitalism, and The 1% and the Rest of us
Semi-analytical finite-element analysis for free and forced wave propagation using COMSOL and LiveLink for Matlab
No full textThe Semi-Analytical Finite-Element (SAFE) method represents one of the most established numerical approaches for predicting the propagation of elastic waves in one-dimensional structures of arbitrary cross-sections. Its implementation in the commercial finite-element software COMSOL Multiphysics has been proposed in recent years; however, it is limited to only the free wave propagation for computing dispersion curves. To overcome this limitation, this paper proposes an extension of this approach that combines COMSOL and its Livelink for Matlab tool. This enables the extraction from COMSOL of the assembled mass and stiffness SAFE matrices to solve problems of both free and forced wave propagation in the Matlab environment. The resulting customised software takesadvantage of both the potential of commercial FE software and the power of Matlab without worrying about compatibility issues. A model of a simply supported plate strip and that of a more complex geometry are implemented to validate, respectively, the SAFE matrix extraction procedure and the implemented forced response formulation. The results agree well with corresponding analytical and numerical results validating the proposed implementation of the SAFE method
1996-1997 Tim Gautreaux
No full textTim Gautreaux is the author of three novels and two earlier short story collections. His work has appeared in The New Yorker, The Best American Short Stories, The Atlantic, Harper’s, and GQ. After teaching for thirty years at Southeastern Louisiana University, he now lives, with his wife, in Chattanooga, Tennessee. (Photo credit: Randy Bergeron)https://egrove.olemiss.edu/grisham_res/1023/thumbnail.jp
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