Analysis of natural time domain entropy fluctuations of synthetic seismicity generated by a simple stick–slip system with asperities

2015 ◽  
Vol 419 ◽  
pp. 23-28 ◽  
Author(s):  
C.A. Vargas ◽  
E.L. Flores-Márquez ◽  
A. Ramírez-Rojas ◽  
L. Telesca
Keyword(s):  
Slip System ◽  
Time Domain ◽  
Stick Slip ◽  
Natural Time

scholarly journals Entropy in the natural time domain

2004 ◽  
Vol 70 (1) ◽  
Author(s):  
P. A. Varotsos ◽  
N. V. Sarlis ◽  
E. S. Skordas ◽  
M. S. Lazaridou
Keyword(s):  
Time Domain ◽  
Natural Time

scholarly journals A plausible universal behaviour of earthquakes in the natural time-domain

2004 ◽  
Vol 80 (6) ◽  
pp. 283-289 ◽  
Author(s):  
Haruo TANAKA ◽  
Panayiotis A. VAROTSOS ◽  
Nicholas V. SARLIS ◽  
Efthimios S. SKORDAS
Keyword(s):  
Time Domain ◽  
Natural Time ◽  
Universal Behaviour

scholarly journals Entropy in Natural Time and the Associated Complexity Measures

2017 ◽  
Author(s):  
Nicholas V. Sarlis
Keyword(s):  
Complex System ◽  
Time Domain ◽  
Time Reversal ◽  
Southern Oscillation ◽  
Complexity Measures ◽  
Natural Time ◽  
Electric Signals ◽  
Atmospheric Phenomena ◽  
Analysis Of Time Series ◽  
New Time

Natural time is a new time domain introduced in 2001. The analysis of time series associated with a complex system in natural time may provide useful information and may reveal properties that are usually hidden when studying the system in conventional time. In this new time domain, an entropy has been defined and complexity measures based on this entropy as well as its value under time-reversal have been introduced and found applications in various complex systems. Here, we review these applications in the electric signals that precede rupture, e.g., earthquakes, in the analysis of electrocardiograms, as well as in global atmospheric phenomena like the El Nino/La Nina Southern Oscillation.

Forced Response Analysis of Shrouded Blades by an Alternating Frequency/Time Domain Method

2006 ◽  
Author(s):  
Shi Yajie ◽  
Hong Jie ◽  
Shan Yingchun ◽  
Zhu Zigen
Keyword(s):  
Relative Motion ◽  
Time Domain ◽  
Dry Friction ◽  
Nonlinear Response ◽  
Harmonic Component ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Response Analysis ◽  
Stick Slip ◽  
Moving Contact

In turbine jet engine, the rotating blades are subjected to cyclic loading, which makes the blades experience the so-called High Cycle Fatigue (HCF). Dry friction is often employed in turbine design to attenuate the blade vibration and increase aeroclastic stability of the turbine. The dry friction dampers are often classified into four types, i.e., blade-to-blade, blade-to-ground, shrouds, and wedge damper, respectively. Compared with the under-platform dampers, shrouds make fan behavior be significantly more complex. It is very difficult to model and predict the nonlinear response of shrouded blades. In the present study, an efficient approach to investigate the nonlinear response of the shrouded blades is suggested using an alternating frequency/time domain (AFT) method. On one hand, the friction force between shrouds is numerically solved in time-domain. The trajectory of relative motion of the moving contact point is traced, and the stick-slip-separation transition for 3-D relative motion of the shroud-contact interface is considered. On the other hand, the response of the shrouded blades is iteratively solved in frequency-domain using Harmonic Balance Method (HBM). In this approach, the influence of high frequency modes of blade, and the coupling of each harmonic component on damping behavior can be taken into account. As an application, the performance of shroud damper is systematically investigated using the AFT method. The influence of shroud-to-shroud preload and contact stiffness on the shroud damping potential is studied. Some valuable results are got to the design of the shroud contact.

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