About: http://webisa.webdatacommons.org/308668144

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	In accordance with the present invention, a void in backfill material, such as soil surrounding a buried conduit may be detected from an acoustic frequency response of the conduit resulting from acoustic excitation of the conduit.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com