scholarly journals On the Spectrum of an Operator Pencil with Applications to Wave Propagation in Periodic and Frequency Dependent Materials

2009 ◽  
Vol 70 (1) ◽  
pp. 231-247 ◽  
Author(s):  
Christian Engström ◽  
Markus Richter
Keyword(s):  
Wave Propagation ◽  
Operator Pencil ◽  
Frequency Dependent ◽  
Spectrum Of An Operator

scholarly journals Frequency-Dependent Breakdown of Wave Propagation Into Fibrillatory Conduction Across the Pectinate Muscle Network in the Isolated Sheep Right Atrium

2002 ◽  
Vol 90 (11) ◽  
pp. 1173-1180 ◽  
Author(s):  
Omer Berenfeld ◽  
Alexey V. Zaitsev ◽  
Sergey F. Mironov ◽  
Arkady M. Pertsov ◽  
José Jalife
Keyword(s):  
Wave Propagation ◽  
Right Atrium ◽  
Frequency Dependent ◽  
Fibrillatory Conduction

A novel wave propagation method for measuring viscoelastic properties of pre-strained materials

2021 ◽  
pp. 1-19
Author(s):  
Pierre Lemerle
Keyword(s):  
Wave Propagation ◽  
Viscoelastic Properties ◽  
Time History ◽  
Main Concept ◽  
Frequency Dependent ◽  
Damping Characteristics ◽  
History Of ◽  
Propagation Methods ◽  
The Time Domain ◽  
Waveform Pattern

Abstract Viscoelastic materials are widely used for vibroacoustic solutions due to their ability to mitigate vibration and sound. Wave propagation methods are based on the measurement of the waveform pattern of a transitory pulse in one-dimensional structures. The time evolution of the pattern can be used to deduce the material elasticity and damping characteristics. The most popular propagation methods, namely Hopkinson bar methods, assume no dispersion, i.e. the complex elasticity modulus is not frequency-dependent. This is not significant for resilient materials such as elastomers. More recent approaches have been developed to measure frequency-dependent properties from a pulse propagating in a slender bar. We showed in previous works how to adapt these techniques for shorter samples of materials, representing a real advance, as extrusion is a cumbersome process for many materials. The main concept was to reconstruct the time history of the wave propagating in a composite structure composed of a long incident bar made of a known material and extended by a shorter sample bar. Then the viscoelastic properties of the sample material were determined in the frequency domain within an inverse method held in the time domain. In industry, most isolation solutions using mounts or bushings must support structural weights. This is why it is particularly interesting to know the viscoelastic properties of the material in stressed state. Here, we show how to overcome this challenging issue. The theoretical framework of the computational approach is detailed and the method is experimentally verified.

scholarly journals Frequency-dependent characterization of THz Sommerfeld wave propagation on single-wires

2005 ◽  
Vol 13 (26) ◽  
pp. 10815 ◽  
Author(s):  
M. Wächter ◽  
M. Nagel ◽  
H. Kurz
Keyword(s):  
Wave Propagation ◽  
Frequency Dependent

Operator Pencil Approach in an Electromagnetic Problem of Symmetric Wave Propagation in a Plane Shielded Waveguide

2020 ◽  
Vol 41 (7) ◽  
pp. 1363-1370
Author(s):  
V. Yu. Martynova ◽  
M. A. Moskaleva ◽  
D. V. Raschetova ◽  
D. V. Valovik
Keyword(s):  
Wave Propagation ◽  
Operator Pencil ◽  
Symmetric Wave

Influence of frequency and saturation on AVO attributes for patchy saturated rocks

Geophysics ◽  
2014 ◽  
Vol 79 (1) ◽  
pp. B19-B36 ◽  
Author(s):  
Bastien Dupuy ◽  
Alexey Stovas
Keyword(s):  
Wave Propagation ◽  
Mode Conversion ◽  
Water Systems ◽  
Frequency Dependent ◽  
Partially Saturated ◽  
Flow Phenomena ◽  
Induced Flow ◽  
Oil Water ◽  
Avo Attributes ◽  
Attenuation And Dispersion

Partially saturated rocks are considered to be major sources of seismic wave velocity dispersion and attenuation in recorded real data. From the physical description of partially saturated gas-water and oil-water reservoirs, we use upscaling theories to compute an equivalent frequency-dependent porous medium. These homogenization methods are associated with mesoscale description of attenuation and dispersion coming from wave-induced flow phenomena. To compute wave propagation, we use numerical codes in the frequency domain that allow us to take into account all the frequency-dependent parameters without approximation or local time steps. In this way, the Biot slow compressional wave is well modeled and its partially diffusive, partially propagative behavior is completely considered. The attenuation and dispersion of the waves in such media are coming partly from the wave mode conversion into diffusive slow waves, not visible on seismograms. But the amplitude of propagative P- and S-waves are mainly affected by these energy losses at interfaces. Using full waveform modeling, we investigate the amplitude versus offset (AVO) attributes with respect to saturation and frequency. For a simple three-layer case, we compute poroelastic wave propagation, extract maximum amplitude with respect to angle, and, through a least-square fitting method, we obtain the AVO attributes for PP- and PS-reflected events. Due to the influence of mesoscale induced-flow phenomena and relatively to the regime of the Biot slow wave, the main results show a strong variability of the AVO attributes with the frequency and a lower variability with the saturation for reflected PP or PS events. We show that gas-water and oil-water systems have similar behaviors. Strong differences between patchy saturation and effective fluid phase theories are highlighted, especially at high frequency, for PP events and for gas-water systems. Then, we conclude that these AVO attributes carry information about the saturation that can be used to estimate the saturation variations in time-lapse studies.

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