Simple initiating impulse

Dependence of detonation velocity on density is shown in Fig. 2.1. Mercury fulminate belongs to the group of primary explosives with a long predetonation zone. In other words, it means that it takes a long time, and uses significant amounts of charge, before the decomposition reaction accelerates from simple initial impulse to fully developed detonation (slow deflagration to detonation transition... 

Scanning electron microscopy Silver fulminate Simple initiating impulse... 

Memory-effect phenomena occur because the typical relaxation times for polymer solutions correspond to times readily accessed experimentally. A disturbance or fluctuation takes place in a polymer solution, and the response to the initial impulse lasts long enough to be experimentally significant. In principle, memory-effect phenomena are equally found for simple liquids and small-molecule solutions. However, characteristic relaxation times for a small-molecule liquid are... 

The spinal cord is the most anatomically inferior portion of the CNS and its functions are at the lowest level of sophistication (see Table 6.1). As mentioned earlier, the spinal cord receives sensory input from the periphery of the body and contains the cell bodies of motor neurons responsible for voluntary and involuntary movements. Once again, the involuntary and neurologically simple reflexes are processed entirely at the level of the spinal cord. Voluntary, deliberate movements are initiated and controlled by thought processes in the cerebrum. The second important function of the spinal cord is to transmit nerve impulses to and from the brain. Ascending pathways carry sensory input to higher levels of the CNS and descending pathways carry impulses from the brain to motor neurons in the spinal cord. 

Although the curves in Figures 13-15 were developed for transient loads defined by total applied forces and inpulses, we could as easily have developed them by initially specifying an applied pressure transient loading, with its accompanying specific impulse, plus a loaded area. So, the concept certainly applies to simple structures under blast loading. The inportant inferences to be drawn from the simple- analyses are that structures respond primarily to peak overpressure if their vibration periods are much shorter than the blast duration, while they respond primarily to specific impulse if their vibration periods are much longer than the blast duration. 

A widely-used model in this class is the direct-interaction with product repulsion (DIPR) model [173—175], which assumes that a generalised force produces a known total impulse between B and C. The final translational energy of the products is determined by the initial orientation of BC, the repulsive energy released into BC and the form of the repulsive force as the products separate. This latter can be obtained from experiment or may be assumed to take some simple form such as an exponential decay with distance. Another method is to calculate this distribution from the quasi-diatomic reflection approximation often used for photodissociation [176]. This is called the DIPR—DIP model ( distributed as in photodissociation ) and has given good agreement for the product translational and rotational energy distributions from the reactions of alkali atoms with methyl iodide. 

Although the mathematics may look a little complicated, the model is in fact very simple. Each phrase is initiated with an impulse, which when passed through the filter, makes the FO contour rise to a local maximum value and then slowly decay. Successive phrases are added to the tails of the previous ones, thus creating the type of pattern seen in figure 9.10. The time constant, a, governs how quickly the phrase reaches its maximum value, and how quickly it falls off after this. 

There are numerous different types of equipment available for use as sonochemical reactors. The initial source of ultrasound comes from transducer devices which convert alternating electrical impulses to mechanical vibrations. Generally these are constructed of either piezoelectric or magnetostrictive material (p. 5). A purely mechanical low-frequency emitter is the whistle system, not frequently used by sonochemists, but of widespread usage in food processing (p. 311). Several set-ups are used to produce low-frequency ultrasoimd, from the simple cleaning baths to much more sophisticated emitters, sometimes using two... 

Whether an explosive is dropped, burned, scraped, or shocked to furnish the first impulse that starts the initiation process, a shock is formed. Initiation of an explosive always goes through a stage in which a shock wave is an important feature. Most theoretical studies at Los Alamos of the initiation properties of explosives have been primarily studies of initiation by shock waves. Modeling of simple pressure-dependent burning combined with shock decomposition of the explosive has resulted in numerical simulation of the burning to detonation process. 

---