Explosion centre

Procida-Vivara islands 55 to 17 ka - Coalescing explosive centres formed of basalt, K-trachybasalt to trachyte pyroclastics. 

The dose resulting from the initial nuclear radiation depends in a complex way on the explosion power and on distance, and on the density variations of air due to the blast (the hydrodynamic increment due to the rarefaction of air behind the shock wave at high explosion energies). Tables 22-1 and 22-2 detail three values of gamma and neutron doses, respectively, and distance (in air from the explosion centre) for three typical explosion energies. Other values can be interpolated or extrapolated. The uncertainty is equal to a factor of two in both ways. 

For an explosion of 1 Mt, about 40 J cm at 3000 m in air from the explosion centre can be observed. Other values can be obtained by the simple scaling laws above. 

There is a finite time interval required for the blast wave to move out from the explosion centre to any particular location. This time interval is dependent upon the energy yield of the explosion and the distance involved. At 1.6 km from a 1 megaton burst, the arrival time would be about 4 s. Initially, the velocity of the shock front is quite high, many times the speed of sound, but as the blast wave progresses outwards, so it slows down as the pressure at the front weakens. Finally, at long ranges, the blast wave becomes essentially a sound wave and its velocity approaches ambient sound velocity. 

The estimate of the explosion energy suffers from the same type of inconvenience of Brode s equation, and the analogy of the explosion of a pressurized gas vessel to a TNT one appears improper in the near field, since the vessel cannot be regarded as a point source. In this case, the correction method uses a virtual distance from the explosion center (Petes, 1971), to fictitiously move the explosion centre with respect to the surface of the expanding gas. The maximum overpressure of the shock wave, i.e. that at the contact surface between the initial expanding gas sphere and the air, is evaluated as (Baker et al., 1983 Prugh, 1988) ... 

Both methods cannot be safely extrapolated in the near field, and both require some adjustment procedure using Baker s method, a discontinuity will occur, not only at the scaled distanc /J = 2, limit for the near field zone, but also at Ji = 3.5, due to a multiplier factor to be used for cylindrical yessels, which change its value from 1.6 to 1.4 at = 3.5 (AIChE/CCPS, 2000). On the contrary, Prugh s method makes use of a virtual distance, to properly adjust the distance from the explosion centre, and no discontinuity is observed in the peak overpressure profiles. Nevertheless, in the near field, the estimates obtained applying both methods likely suffer from greater uncertainty on the other hand, it should be honestly admitted that, in the near field, peak overpressure values often... 

I would like to thank Dr. Geraint O. Thomas (Centre for Explosion Studies, Department of Physics, University of Wales, Aberystwyth, UK) for offering to write Chapter 4. He prepared the first draft, but due to a sabbatical in Japan and other research commitments, he was unable to write the revisions. However, he did make constructive comments and suggestions on the revisions that I wrote. In addition, I would like to thank the following other individuals who provided me with technical data and other assistance based on their knowledge of flame arresters and combustion science and technology G. Binks (IMI Amal), R. Butler (Enardo). K. Chatrathi... 

Kjaldman, L., and R. Huhtanen. 1985. Simulation of flame acceleration in unconfined vapor cloud explosions. Research Report No. 357. Technical Research Centre of Finland. 

Finally, CCPS is grateful to Dr. B. H. Hjertager, Telemark Institute of Technology and Telemark Innovation Centre, Porsgrunn, Norway, for preparing A Case Study of Gas Explosions in a Process Plant Using a Three-dimensional Computer Code (Appendix F). 

Kind R (2007) Evidence for Ferroelectric Nudeation Centres in the Pseudo-spin Glass System Rbi x(ND4)xD2P04 A 87Rb NMR Study. 124 119-147 Klapotke TM (2007) New Nitrogen-Rich High Explosives. 125 85-121 Kobuke Y (2006) Porphyrin Supramolecules by Self-Complementary Coordination 121 ... 

The violent or explosive reactions exhibited by glycerol in contact with many solid oxidants are due to its unique properties of having three centres of reactivity, of being a liquid which ensures good contact, and of high boiling point and viscosity which prevents dissipation of oxidative heat. The difunctional, less viscous liquid glycols show similar but less extreme behaviour. 

Procedures relevant to safe handling and use are discussed. Perchloryl fluoride is stable to heat, shock and moisture, but is a powerful oxidiser comparable with liquid oxygen. It fonns flammable and/or explosive mixtures with combustible gases and vapours [1,2]. It only reacts with strongly nucleophilic centres, and the by-product, chloric acid is dangerously explosive in admixture with organic compounds [3], Safety aspects of practical use of perchloryl fluoride have been reviewed [4],... 

An unknown event disturbed the equilibrium of the interstellar cloud, and it collapsed. This process may have been caused by shock waves from a supernova explosion, or by a density wave of a spiral arm of the galaxy. The gas molecules and the particles were compressed, and with increasing compression, both temperature and pressure increased. It is possible that the centrifugal forces due to the rotation of the system prevented a spherical contraction. The result was a relatively flat, rotating disc of matter, in the centre of which was the primeval sun. Analogues of the early solar system, i.e., protoplanetary discs, have been identified from the radiation emitted by T Tauri stars (Koerner, 1997). 

A GW gives rise to a quadrupolar deformation normal to the direction of propagation. The deformation can be described by means of a dimensionless strain amplitude h = AL/L, where AL is the deformation of a region of space-time separated by a distance L. For example, a supernova explosion, with a mass conversion into GWs of 1% of the total mass, at a distance of 10 kpc (roughly in the centre of our galaxy), would cause a strain on earth of h 3 x 10-18 [50],... 

Figure 9.2 Left 4396 standard accelerometer. Centre ATEX 5874 Accelerometer which is certified for use where explosion proof sensors are required. Right Acoustic Emission (AE) sensor from Kistler. Reprinted from [7]. Copyright 2006, with permission from Elsevier.

Fig. 5.4. Schematic evolution of the internal structure of a star with 25 times the mass of the Sun. The figure shows the various combustion phases (shaded) and their main products. Between two combustion phases, the stellar core contracts and the central temperature rises. Combustion phases grow ever shorter. Before the explosion, the star has assumed a shell-like structure. The centre is occupied by iron and the outer layer by hydrogen, whilst intermediate elements are located between them. CoUapse followed by rebound from the core generates a shock wave that reignites nuclear reactions in the depths and propels the layers it traverses out into space. The collapsed core cools by neutrino emission to become a neutron star or even a black hole. Most of the gravitational energy liberated by implosion of the core (some 10 erg) is released in about 10 seconds in the form of neutrinos. (Courtesy of Marcel Amould, Universite Libre, Brussels.)...

This treatment, which is due to Semenov, includes two assumptions, a uniform reactant temperature and heat loss by convection. While these may be reasonable approximations for some situations, e.g. a well-stirred liquid, they may be unsatisfactory in others. In Frank-Kamenetskii s theory, heat transfer takes place by conduction through the reacting mixture whose temperature is highest at the centre of the vessel and falls towards the walls. The mathematics of the Frank-Kamenetskii theory are considerably more complicated than those of the simple Semenov treatment, but it can be shown that the pre-explosion temperature rise at the centre of the vessel is given by an expression which differs from that already obtained by a numerical factor, the value of which depends on the geometry of the system (Table 7). 

Another method was to dip blackpowder pellets in paraffin wax. This rendered them waterproof, and also surrounded them with a cooling sheath . A blasting powder made in this form called Bobbinite was introduced in Great Britain. It will be discussed later. These half-measures brought little improvement and attention was centred on the use of ammonium nitrate explosives. 

The explosives in Belgium are now classified into 4 types, according to 1 Association de Fabricants Beiges d Explosifs et le Centre de Recherches Scientifiques et Techniques pour l lndustrie des Produits Explosifs [76] (Tables 110-112). 

Nitrocubanes are probably the most powerful explosives with a predicted detonation velocity of >10,000 ms-1. Cubanes were first synthesised at the University of Chicago, USA by Eaton and Cole in 1964. The US Army Armament Research Development Centre (ARDEC) then funded development into the formation of octanitrocubane [(ONC) (C8N8016)] and heptanitrocubane [(HpNC) (C8N7014)]. ONC and HpNC were successfully synthesised in 1997 and 2000 respectively by Eaton and co-workers. The basic structure of ONC is a cubane molecule where all the hydrogens have been replaced by nitro groups (1.6). HpNC is denser than ONC and predicted to be a more powerful, shock-insensitive explosive. 

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