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Waves dissipate energy when they propagate through real medium. Theoretical study of waves is one of important way to understand the nature of waves in medium with dissipation. The study points out that the theoretical solution to the wave equation describing a disturbance propagating in a dissipative medium is not unique, which is determined by the dissipation mechanism of the medium. A new general solution is proposed by assuming that the attenuations of disturbance can occur in the time and space domains. The general solution is further used in case studies. The properties of viscoelastic waves propagating in the Kelvin-Voigt medium and electromagnetic waves propagating in conductive medium with the reciprocal attenuation in time and space domains are analyzed. The result shows that the attenuation mechanism has an obvious influence on the properties of waves in the dissipative medium when the wave equations are the same.
The time reversal symmetry of the wave equation allows wave refocusing back at the source. However, this symmetry does not hold in lossy media. We present a new strategy to compensate wave amplitude losses due to attenuation. The strategy leverages t
Experimental results and their interpretations are presented on the nonlinear acoustic effects of multiple scattered elastic waves in unconsolidated granular media. Short wave packets with a central frequency higher than the so-called cut-off frequen
Heterogeneity can be accounted for by a random potential in the wave equation. For acoustic waves in a fluid with fluctuations of both density and compressibility (as well as for electromagnetic waves in a medium with fluctuation of both permittivity
A low loss propagating electromagnetic wave is shown to exist at a gradual interface between two lossy conductive media. The electromagnetic frequency range of this phenomenon may span from UV optics to RF range. In particular, it is demonstrated tha
We show that there exists an exact solution for a lossless and reciprocal periodic surface impedance which ensures full conversion of a single-mode surface wave propagating along the impedance boundary to a single plane wave propagating along a desir