Phase-velocity dispersion curves and small-scale geophysics using noise correlation slantstack technique

Measurement of phase velocity dispersion curves and group velocities in a plate using leaky Lamb waves

The guided wave has been widely employed to characterize thin plates and layered media. The dispersion curves of phase and group velocities are essential for the quantitative application of guided waves. The technique using leaky Lamb wave (LLW) is one of the excellent methods to obtain dispersion curves. In the present work, a fully automated system for the measurement of LLW has been develope...

Repulsion of phase-velocity dispersion curves and the nature of plate vibrations

Direct Imaging of Group Velocity Dispersion Curves in Shallow Water

Geometric dispersion is commonly observed in shallow water marine data due to post-critical multiples in the water layer over a hard seafloor. Characteristics of the guided waves include formation of distinct propagation modes and associated divergence of phase and group velocity. Methods have been available since 1981 to image phase velocity dispersion curves. Here we report a method to direct...

Phase-Induced Intensity Noise Reduction with Improved Group Velocity Dispersion Tolerance in SAC-OCDMA Systems

The demand for efficient optical communication systems has fuelled considerable research in developing techniques for eradicating phase-induced intensity noise (PIIN) in spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA). This paper investigates the use of modified-AND subtraction detection technique to mitigate PIIN in SAC-OCDMA systems. The simulation results show tha...

Noise Suppressor using Zero Phase Signal and Accumulated Spectrum Technique

This paper proposes a wide-band noise reduction method using temporal accumulated spectrum and zero phase (ZP) signal. In the previous study, we replace the ZP signal around the origin with the ZP signal in the second or latter period to get an estimated speech ZP signal. For very low SNR environment, reliable period estimation is difficult. This paper presents a study of period estimation in n...