Transverse oscillations of a rod with hysteresis energy dissipation under random excitation

1987 ◽  
Vol 19 (2) ◽  
pp. 213-218
Author(s):  
L. M. Ryzhkov ◽  
Yu. A. Mamzenko
Keyword(s):  
Energy Dissipation ◽  
Random Excitation ◽  
Transverse Oscillations

scholarly journals Excitation of decay-less transverse oscillations of coronal loops by random motions

2020 ◽  
Vol 633 ◽  
pp. L8 ◽  
Author(s):  
A. N. Afanasyev ◽  
T. Van Doorsselaere ◽  
V. M. Nakariakov
Keyword(s):  
Broad Band ◽  
Random Excitation ◽  
Forced Oscillations ◽  
Oscillatory Process ◽  
Coronal Loops ◽  
Alternative Mechanism ◽  
Steady Flows ◽  
Kink Waves ◽  
Random Motions ◽  
Transverse Oscillations

Context. The relatively large-amplitude decaying regime of transverse oscillations of coronal loops has been known for two decades and has been interpreted in terms of magnetohydrodynamic kink modes of cylindrical plasma waveguides. In this regime oscillations decay in several cycles. Recent observational analysis has revealed so-called decay-less, small-amplitude oscillations, in which a multi-harmonic structure has been detected. Several models have been proposed to explain these oscillations. In particular, decay-less oscillations have been described in terms of standing kink waves driven with continuous mono-periodic motions of loop footpoints, in terms of a simple oscillator model of forced oscillations due to harmonic external force, and as a self-oscillatory process due to the interaction of a loop with quasi-steady flows. However, an alternative mechanism is needed to explain the simultaneous excitation of several longitudinal harmonics of the oscillation. Aims. We study the mechanism of random excitation of decay-less transverse oscillations of coronal loops. Methods. With a spatially one-dimensional and time-dependent analytical model taking into account effects of the wave damping and kink speed variation along the loop, we considered transverse loop oscillations driven by random motions of footpoints. The footpoint motions were modelled by broad-band coloured noise. Results. We found the excitation of loop eigenmodes and analysed their frequency ratios as well as the spatial structure of the oscillations along the loop. The obtained results successfully reproduce the observed properties of decay-less oscillations. In particular, excitation of eigenmodes of a loop as a resonator can explain the observed quasi-monochromatic nature of decay-less oscillations and the generation of multiple harmonics detected recently. Conclusions. We propose a mechanism that can interpret decay-less transverse oscillations of coronal loops in terms of kink waves randomly driven at the loop footpoints.

Parameter Optimization of Liquid Viscous Damper Based on Energy and Control Indexes under Random Excitation

2015 ◽  
Vol 777 ◽  
pp. 64-68
Author(s):  
Li Xian Wang ◽  
Qi Yang Liu ◽  
Sheng Kui Di ◽  
Chang Sheng Xiang
Keyword(s):  
Energy Dissipation ◽  
Structural Control ◽  
Seismic Waves ◽  
Random Excitation ◽  
Steel Tube ◽  
Arch Bridge ◽  
Energy Evaluation ◽  
Evaluation Functions ◽  
Optimization Parameters ◽  
Control Evaluation

The damper parameter of a concrete-filled steel tube arch bridge is optimized. Random Fourier spectrum based on physical model is used to synthesis the random time-domain excitation. Four evaluation functions have been constructed as optimization of the objective functions based on energy dissipation and structural control indexes. Comparing two energy evaluation function combinations and traditional control evaluation functions, the damper optimization parameters have been obtained. Result shows that: Optimized damper parameters of concrete-filled steel tubular arch bridge under various seismic waves have high damping effect. After introducing the energy dissipation indexes, evaluation functions avoided the extreme value disadvantages of the traditional target, the final optimization results could be more economical and practical.

Study on Reliability of Structure with Energy Dissipation Dampers

2011 ◽  
Vol 383-390 ◽  
pp. 6396-6403
Author(s):  
Zhi Qiang Bai ◽  
Wen Feng Liu ◽  
Huan Qiang Luan
Keyword(s):  
Energy Dissipation ◽  
Random Excitation ◽  
Viscoelastic Dampers ◽  
Random Method ◽  
Determinant Factor

In this paper, Kanai-Tajimi spectrum as earthquake random excitation is applied. A Structure with Viscoelastic Dampers is analyzed by random method and reliability of energy dissipation is presented. The effect of energy dissipation of viscoelastic dampers added to building is studied under four working situations. The result of calculation indicates that the reliability of energy dissipation will be higher if more dampers are installed. Supposing that the quantity of dampers is fixed, the reliability of energy dissipation will be decrescent if energy dissipation degree is larger. If the reliability of energy dissipation is fixed, the dampers parameter is the determinant factor.

Energy Dissipation Processes of Singlet Excited 1-Hydroxyfluorenone and its Hydrogen-Bonded Complex with N-Methylimidazole

2004 ◽  
Author(s):  
Krisztina Sebők-Nagy ◽  
László Biczók ◽  
Akimitsu Morimoto ◽  
Tetsuya Shimada ◽  
Haruo Inoue
Keyword(s):  
Energy Dissipation ◽  
Dissipation Processes ◽  
Hydrogen Bonded
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