Wave amplitude decay driven by anharmonic potential in nonlinear mass-in-mass systems

2020 ◽  
Vol 117 (12) ◽  
pp. 124101
Author(s):  
S. Fiore ◽  
G. Finocchio ◽  
R. Zivieri ◽  
M. Chiappini ◽  
F. Garescì
Keyword(s):  
Wave Amplitude ◽  
Anharmonic Potential

Density Wave Measurements in a Rectangular Clarifier

1983 ◽  
Vol 18 (1) ◽  
pp. 129-150 ◽  
Author(s):  
Mark K. Watson ◽  
R.R. Hudgins ◽  
P.L. Silveston
Keyword(s):  
Power Spectrum ◽  
Internal Wave ◽  
Internal Waves ◽  
Wave Motion ◽  
Wave Amplitude ◽  
Suspended Solids ◽  
Small Volume ◽  
Density Wave ◽  
Measure Concentration ◽  
Wave Measurements

Abstract Internal wave motion was studied in a laboratory rectangular, primary clarifier. A photo-extinction device was used as a turbidimeter to measure concentration fluctuations in a small volume within the clarifier as a function of time. The signal from this device was fed to a HP21MX minicomputer and the power spectrum plotted from data records lasting approximately 30 min. Results show large changes of wave amplitude as frequency increases. Two distinct regions occur: one with high amplitudes at frequencies below 0.03 Hz, the second with very small amplitudes appears for frequencies greater than 0.1 Hz. The former is associated with internal waves, the latter with flow-generated turbulence. Depth, velocity in the clarifier and inlet suspended solids influence wave amplitudes and the spectra. A variation with position or orientation of the probe was not detected. Contradictory results were found for the influence of flow contraction baffles on internal wave amplitude.

scholarly journals Time Course of ECG Depolarization and Repolarization Changes during Ischemia in PTCA Recordings

2004 ◽  
Vol 43 (01) ◽  
pp. 43-46 ◽  
Author(s):  
J. García ◽  
G. Wagner ◽  
R. Bailón ◽  
L. Sörnmo ◽  
P. Laguna ◽  
...  
Keyword(s):  
Time Course ◽  
Wave Amplitude ◽  
Temporal Evolution ◽  
Delayed Response ◽  
S Wave ◽  
Ecg Changes ◽  
T Complex ◽  
Karhunen Loeve Transform ◽  
Low Amplitude ◽  
Electrocardiogram Ecg

Summary Objectives: In this work we studied the temporal evolution of changes in the electrocardiogram (ECG) as a consequence of the induced ischemia during prolonged coronary angioplasty, comparing the time course of indexes reflecting depolarization and those reflecting repolarization. Methods: We considered both local (measured at specific points of the ECG) and global (obtained from the Karhunen-Loève transform) indexes. In particular, the evolution of Q, R and S wave amplitudes during ischemia was analyzed with respect to classical indexes such as ST level. As a measurement of sensitivity we used an Ischemic Changes Sensor (ICS), which reflects the capacity of an index to detect changes in the ECG. Results: The results showed that, in leads with low-amplitude ST-T complexes, the S wave amplitude was more sensitive in detecting ischemia than was the commonly used index ST60. It was found that in such leads the S wave amplitude initially exhibited a delayed response to ischemia when compared to ST60, but its performance was better from the second minute of occlusion. The global indexes describing the ST-T complex were, in terms of the ICS, superior to the S wave amplitude for ischemia detection. Conclusions: Ischemic ECG changes occur both at repolarization and depolarization, with alterations in the depolarization period appearing later in time. Local indexes are less sensitive to ischemia than global ones.

scholarly journals B-PO02-063 ELECTROGRAM R-WAVE AMPLITUDE FOR DIFFERENT SENSING VECTORS ACROSS DIFFERENT POSTURES FOR PATIENTS WITH AN EXTRAVASCULAR IMPLANTABLE CARDIOVERTER DEFIBRILLATOR

Heart Rhythm ◽  
2021 ◽  
Vol 18 (8) ◽  
pp. S121-S122
Author(s):  
Yuanzhen Liu ◽  
Xusheng Zhang ◽  
Paul J. DeGroot ◽  
Christopher Wiggenhorn ◽  
Samuel Liang ◽  
...  
Keyword(s):  
Implantable Cardioverter Defibrillator ◽  
Wave Amplitude ◽  
Cardioverter Defibrillator ◽  
R Wave Amplitude

scholarly journals Rapid estimation of tsunami earthquake magnitudes at local distance

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Akio Katsumata ◽  
Masayuki Tanaka ◽  
Takahito Nishimiya
Keyword(s):  
Magnitude Estimation ◽  
Seismic Wave ◽  
Seismic Waves ◽  
Wave Amplitude ◽  
Amplitude Distribution ◽  
Distribution Method ◽  
Finite Fault ◽  
Tsunami Earthquakes ◽  
Tsunami Earthquake ◽  
The Moment

AbstractA tsunami earthquake is an earthquake event that generates abnormally high tsunami waves considering the amplitude of the seismic waves. These abnormally high waves relative to the seismic wave amplitude are related to the longer rupture duration of such earthquakes compared with typical events. Rapid magnitude estimation is essential for the timely issuance of effective tsunami warnings for tsunami earthquakes. For local events, event magnitude estimated from the observed displacement amplitudes of the seismic waves, which can be obtained before estimation of the seismic moment, is often used for the first tsunami warning. However, because the observed displacement amplitude is approximately proportional to the moment rate, conventional magnitudes of tsunami earthquakes estimated based on the seismic wave amplitude tend to underestimate the event size. To overcome this problem, we investigated several methods of magnitude estimation, including magnitudes based on long-period displacement, integrated displacement, and multiband amplitude distribution. We tested the methods using synthetic waveforms calculated from finite fault models of tsunami earthquakes. We found that methods based on observed amplitudes could not estimate magnitude properly, but the method based on the multiband amplitude distribution gave values close to the moment magnitude for many tsunami earthquakes. In this method, peak amplitudes of bandpass filtered waveforms are compared with those of synthetic records for an assumed source duration and fault mechanism. We applied the multiband amplitude distribution method to the records of events that occurred around the Japanese Islands and to those of tsunami earthquakes, and confirmed that this method could be used to estimate event magnitudes close to the moment magnitudes.

Motion periodicity and bifurcation of a wave excited hopping ball

2019 ◽  
Vol 475 (2228) ◽  
pp. 20190137
Author(s):  
Gaurang Ruhela ◽  
Anirvan DasGupta
Keyword(s):  
Wave Amplitude ◽  
Harmonic Wave ◽  
Inelastic Collisions ◽  
Loss Of Stability ◽  
Elastic Surface ◽  
Minimum Frequency ◽  
Surface Motion ◽  
Return Map ◽  
Ball Problem ◽  
Subsequent Loss

We consider the problem of a hopping ball excited by a travelling harmonic wave on an elastic surface. The ball, considered as a particle, is assumed to interact with the surface through inelastic collisions. The surface motion due to the wave induces a horizontal drift in the ball. The problem is treated analytically under certain approximations. The phase space of the hopping motion is captured by constructing a phase-velocity return map. The fixed points of the return map and its compositions represent periodic hopping solutions. The linear stability of the obtained periodic solution is studied in detail. The minimum frequency for the onset of periodic hops, and the subsequent loss of stability at the bifurcation frequency, have been determined analytically. Interestingly, for small values of wave amplitude, the analytical solutions reveal striking similarities with the results of the classical bouncing ball problem.

Study on Nonlinear Motion Behavior of Coupled Heave-Pitch for the Classic Spar Platform Based on AQWA

2012 ◽  
Vol 170-173 ◽  
pp. 2170-2174 ◽  
Author(s):  
Song Sang ◽  
Yuan Zhou ◽  
Xue Liang Jiang
Keyword(s):  
Incident Wave ◽  
Wave Amplitude ◽  
Wave Period ◽  
Critical Periods ◽  
Spar Platform ◽  
Natural Period ◽  
Nonlinear Motion ◽  
Motion Characteristic ◽  
Instability Parameter ◽  
Motion Behavior

This paper used AQWA software to research the nonlinear motion characteristic of heave-pitch coupling of classical Spar platform in regular waves. With classic Spar platform as an example, the wave amplitude and periodic changes’ effect to the nonlinear motion behavior of coupled heave-pitch is researched. After calculation, the critical periods corresponding to the different incident wave amplitude are obtained, based which, gets the instability parameter domain of coupling resonance of platform in the wave period-amplitude plane. The results in this paper show that the heave-pitch coupled resonance of platform depends on the wave amplitude and the ratio of the natural period of heave and pitch, and the incident wave period.

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