Generated by an explosion

Maximum reduced explosion overpressure PreThe maximum pressure generated by an explosion of a dust-air mixture in a vented or suppressed vessel under systematically varied dust concentrations. 

In experiments of Skidmore Hart, the overdriven detonation waves were generated by an "explosive driven plate impact technique , which was essentially as follows (Ref 15, p 48) ... 

The airborne shock wave or acoustic transient generated by an explosion -> Detonation. 

Depending on the medium in which the pressure-wave generated by an explosive expands into its surroundings, one can distinguish between... 

The seismic wave generated by an explosion is a compression wave the vibration is parallel to the direction of propagation of the wave. On the surface, the initial movement of this wave corresponds to a lifting of the ground. However, this is not the only propagation mode for seismic waves. Three other types are possible shear wave. Love wave and Rayleigh wave. 

The airborne acoustic or shock wave generated by an explosion - Detonation, -> Fuel Air Explosives, - Thermobaric Explosives. 

In process plants apparatuses are connected by pipes. Therefore pressure waves generated by an explosion in an apparams can cause pressure loads in other apparatuses. In order to avoid this, isolation of apparatuses can be achieved by flame arresters (or other devices). They are described below following [14—16]. These impede the propagation of an explosion and hence reduce its consequences (level 4 of Table 4.1). They can be applied to mixtures of flammable gases or vapours with oxidants (usually the oxygen in air) or mixtures of dusts and oxidants. 

Figure 17-6. Time history of the pressure difference generated by an explosive wave.

Besides the protection afforded by barriers, sometimes the reinforcement of structures exposed to a possible explosive blast is considered. It is useful to remember in this connection that the time history of the pressure difference with reference to the preexisting one, generated by an explosive wave at a point a certain distance from the blast, is of the type shown in Figure 17-6. 

The intensity of the shock wave generated by an explosion depends on the height of the explosion and distance from the explosion. However, for objects on the ground and for explosions within a few kilometres, the peak pressure generated is shown in Figure 22-2 for the equivalent energy of 1 kt. 

The free surface motion of water-air Interface accelerated by the impact of a shock Impulse generated by an explosive has been observed by means of holographic technique. The results of the analysis of the holograms allowed us to confirm and to clarify the role of cavitation phenomena, which ... 

Then a final apparently steady, deton was established at 8280 m/sec 4) Skidmore Hart (Bet 88) produced overdriven detonation waves in Comp B carrying increased velocities and pressures up to twice the C-J pressure by an explosive driven plate impact technique. The basis of the technique is to explosively propel a metal driver plat e at a similar target plate on which rests a sample layer of expl backed by a further layer of inert solid. When the driver plate vel is sufficiently high this process generates a steady overdriven deton wave in the expl unless (or until) it is overtaken by the rarefaction wave from the rear of the driver plate. 

Detonation is a chemical reaction given by an explosive substance in which produces a shock wave. High temperature and pressure gradients are generated in the wave front, so that the chemical reaction is initiated instantaneously. Detonation velocities lie in the approximate range of 1500 to 9000 m/s = 5000 to 30000 ft/s slower explosive reactions, which are propagated by thermal conduction and radiation, are known as -> Deflagration. 

Reactive chemicals sometimes cause an explosion after long storage. The cause of the explosion may be the generation of an explosive peroxide. In order to avoid such accidents, one should be familiar with the atomic groups which generate peroxides. These groups are listed in the table 3 41. Based on Bretherick s book, a table 8 of spontaneously combustible substances, water—reactive substances, and unstable substances has been prepared. This table is in the Japanese edition of this book. It may be helpful for individuals to prepare similar tables of structural formulas specific to hazardous substances by using data from references. 

Selection algorithms must be able to select building blocks in a way that an optimized set of products is generated by combinatorial explosion. Genetic or evolutionary algorithms are most commonly used for this optimization step [70, 101, 109, 130]. 

Today there are several other ways of diamond synthesis besides the HPHT method. For example, it is possible to utilize the pressure of a shock-wave generated in an explosion. This process mostly yields powdery products with particle sizes in the range of micrometers (1 mm at max.) that may be employed for industrial purposes as well. Moreover, very small diamonds (5-20 nm) can be made by reacting explosives in confined containers. Diamond films are produced on various substrates by chemical vapor deposition (CVD method using methane as a carbon source. Detonation synthesis and vapor deposition will be described in detail in Chapters 5 and 6. 

Besides the direct generation of nanodiamond in a detonation, the required pressure can also be achieved by the achon of an external shock wave. Usually, the latter is induced by an explosion too and compresses the carbon material that is enclosed in a kind of capsule. A catalyst Hke, for example, copper, iron, aluminum, nickel, or cobalt is frequently employed in this process. It has already been mentioned in the introduction that nanoscale diamond particles had been prepared quite early by the conversion of other carbon materials in a shock wave. Soon after this discovery, researchers of the DuPont Corp. developed a method also based on shock action that yields very small diamond particles. These are processed by subsequent sintering to give utterly durable cutting and poHshing tools. 

Industrial flres are known to cause disasters, affecting both life and property. Literature is rich on this subject If the loss of human life is not caused as a result of convected and radiant heat or direct contact with flames, it may be caused by suffocation due to the inhalation of toxic combustion products or to lack of oxygen. In an explosion workers may by injured by direct impact from debris or by the blast or over-pressure generated by the explosion. Some chemicals are specifically fomulated to explode and are referred to as explosives. Others such as the organic peroxides and some azo and nitro compounds, explode because they are unstable. These may be formed as intomediates in chemical reactions or as the result of a reaction between incompatible chemicals. Table... 

Meteorites come from more massive parents (mainly minor planets - i.e, asteroids - but also Mars and our Moon) and to get to Earth, their immediate predecessors - meteoroids - can only be excavated from its parent body by an explosive impact. This impact almost always generates short-lived but intense shock effects, results of which are present in many individual meteorites and groups of them (7) but which I do not discuss further here. The impact also provides the impulse necessary for the meteoroid to exceed the parent body s escape velocity e.g. 5.4 km/s for Mars. Thus, meteoritic minerals provide barometers for shock pressures up to -60 GPa (6x10 atm) corresponding to post-shock temperatures >1250°C at much higher pressures (temperatures), these materials vaporize. Incidentally, this explains why Earth receives meteorites from Mars but not Venus, which is closer Venus escape velocity is... 

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