We retrieve reflected plane waves by applying seismic interferometry to the recorded ground motion from a cluster of earthquakes. We employ upgoing/downgoing P/S wavefield decomposition, time windows, time reversal, and multi-dimensional deconvolution (MDD) to improve the quality of the extraction of reflected waves with seismic interferometry. Because MDD interferometry requires the separation...

Multiple-scattered waves usually are not useful for creating deterministic images of the interior of elastic media. However, in many applications, one is not so much interested in making a deterministic image as in detecting changes in the medium. Cases in point are volcano monitoring and measuring the change in hydrocarbon reservoirs during enhanced recovery operations. Coda wave interferometr...

AN OPTIC FIBER SENSOR FOR PARTIAL DISCHARGE ACOUSTIC DETECTION by Xiaodong Wang Partial discharge (PD) is a very common problem in operating power transformers and is one of the factors that could lead to failure of power transformers, leading to power outage and expensive repairs. The acoustic wave induced by PD can be measured and used for monitoring, diagnosing, and locating potential failur...

This study introduces optical feedback interferometry as a simple and effective technique for the two-dimensional visualisation of acoustic fields. We present imaging results for several pressure distributions including those for progressive waves, standing waves, as well as the diffraction and interference patterns of the acoustic waves. The proposed solution has the distinct advantage of extr...

We propose a novel spatial phase-shifting interferometry that exploits a genetic algorithm to compensate for geometric errors. Spatial phase-shifting interferometry is more suitable for measuring objects with properties that change rapidly in time than the temporal phase-shifting interferometry. However, it is more susceptible to the geometric errors since the positions at which interferograms ...