Ground vibration boom Ground vibration boom Ground vibration boom is a phenomenon of very large increase in ground vibrations generated by high-speed railway trains travelling at speeds higher than the velocity of Rayleigh surface waves in the supporting ground. This phenomenon, which is similar to a sonic boom from supersonic aircraft, was theoretically predicted in 1994. Its first experimental observation took place in 1997-1998 on the newly built high-speed railway line in Sweden (from Gothenburg to Malmo) for high-speed trains X 2000. At some locations along this line characterised by very soft ground (near Ledsgard) the Rayleigh wave velocity was as low as
Shock tube detonator One manufacturer estimates that over 2 billion feet of shock tube are used each year worldwide, in commercial blasting, military demolition, theatrical special effects, automobile airbags, aircraft escape systems, IED initiation and professional fireworks. Shock tube detonator A shock tube detonator is a non-electric explosive fuze or initiator in the form of small-diameter hollow plastic tubing used to transport an initiating signal to an explosive charge by means of a percussive wave traveling the length of the tube. It was invented by Per Anders Persson of Nitro Nobel AB, patented, and sold by them under the registered trademark Nonel, containing