Surface wave of the r order terms due to the point-like horizontal excitation source (L).

In this letter, the higher order terms of the time-harmonic solution due to a point-like horizontal excitation source are investigated. It is found that the surface wave of the r order terms polarize in both radial and azimuthal directions, complementing the findings in the literature. At the ground surface, the polarization distribution of this wave demonstrates similar behavior as the magnetic induction lines of a magnetic dipole.

On Image Fusion of Ground Surface Vibration for Mapping and Locating Underground Pipeline Leakage: An Experimental Investigation.

This paper is concerned with imaging techniques for mapping and locating underground pipeline leakage. Ground surface vibrations induced by the propagating axisymmetric wave can be measured by an array of acoustic/vibration sensors, with the extraction of magnitude information used to determine the position of leak source. A method of connected graph traversal is incorporated into the vibroacoustic technique to obtain the spatial image with better accuracy compared to the conventional magnitude contour plot.

Use of PVDF Wire Sensors for Leakage Localization in a Fluid-Filled Pipe.

The detection and location of pipeline leakage can be deduced from the time difference between the arrival leak signals measured by sensors placed at the pipe access points on either side of a suspected leak. Progress has been made in this area to offer a potential improvement over the conventional cross-correlation method for time delay estimation. This paper is concerned with identifying suitable sensors that can be easily deployed to monitor the pipe vibration due to the propagation of leak noise along the pipeline.