More efficient satellite launch platform on the horizon

An efficient and cost-effective satellite launch platform could soon be a reality in Australia thanks to a world first engine that's being developed by University of Sydney combustion experts.

LLNL releases newly declassified nuclear test videos

Researchers at Lawrence Livermore National Laboratory (LLNL) released 62 newly declassified videos today of atmospheric nuclear tests films that have never before been seen by the public.

Remembering the Vela incident

Thirty-six years ago today, a strange event was detected over the Southern Indian Ocean that remains controversial. On September 22nd, 1979, an American Vela Hotel satellite detected an atmospheric explosion over the southern ...

Geophysicists prep for massive 'ultrasound' of Mount St. Helens

(Phys.org) —A small army of 75 geophysicists is set to converge on Mount St. Helens this weekend to begin final preparations for the equivalent of a combined ultrasound and CAT scan of the famous volcano's internal plumbing. ...

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Detonation

Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases. The velocity of detonations in solid and liquid explosives is much higher than that in gaseous ones, which allows far clearer resolution of the wave system in the latter.[clarification needed What does phrase "resolution of the wave system" mean?]

Gaseous detonations normally occur in confined systems but are occasionally observed in large vapor clouds. They are often associated with a gaseous mixture of fuel and oxidant of a composition, somewhat below conventional flammability limits. There is an extraordinary variety of fuels that may be present as gases, as droplet fogs and as dust suspensions. Other materials, such as acetylene, ozone and hydrogen peroxide are detonable in the absence of oxygen, fuller lists are given by both Stull and Bretherick. Oxidants include halogens, ozone, hydrogen peroxide and oxides of nitrogen and chlorine.

In terms of external damage, it is important to distinguish between detonations and deflagrations where the exothermic wave is subsonic and maximum pressures are at most a quarter[citation needed] of those generated by the former. Processes involved in the transition between deflagration and detonation are covered thoroughly by Nettleton.

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