The team has tested the device on a variety of different kinds of pipes -- concrete, PVC, clay -- blocked up with a different sizes and amounts of sandbags and bricks. The technique is not affected by twists and turns in the pipes. For the moment, only empty, air-filled pipes have been tested. In theory, the technique should work just as well with fluid-filled pipes, though further work would be needed to compensate for the dynamics of the fluid.
The talk "Detecting and localizing pipe changes via matched field processing" (4aSP7) by Alex Tolstoy et al is at 10:45 on Thursday, May 21. Abstract: http://asa.aip.org/web2/asa/abstracts/search.may09/asa874.html
14) LISTENING TO LEVEES
Many dams are made of earthen substances such as soil, a granular material with tiny constituent particles that interact amongst themselves. When water is also present in soil, capillary (suction) forces are at work too. Sound waves can be sent into soil to measure properties such as porosity, temperature, and water content. This kind of testing is particularly important when an upper layer of soil is dry and an underlying layer wet. Then the upper layer becomes unstable and landslides can occur.
Zhiqu Lu of the University of Mississippi will report on a newer, higher-precision device, one employing laser sensing of ground vibrations, for the monitoring of levees and dams using sound waves in a non-invasive way down to depths of several meters. (Paper 1pPA2)
The talk "Effects of soil water potential and moisture content on sound speed" (1pPA1) by Zhiqu Lu et al is at 1:30 p.m. on Monday, May 18. Abstract: http://asa.aip.org/web2/asa/abstracts/search.may09/asa159.html<
|Contact: Jason Bardi|
American Institute of Physics