Fragmentation theory

Which of the two fragmentation theories is more appropriate has not yet been firmly established. The more recent energy-horizon theory appears to have a more solid thermodynamic basis and the theory has the potential of providing a broader description of spall fragmentation phenomena. 

Several further comparisons attest to the universal nature of the statistical fragmentation theory. In Fig. 8.28 the consequences of a nuclear fragmentation event brought about by the 70 MeV per nucleon collision of a carbon nucleus with a silver nucleus is shown (Greiner and Stocker, 1985). In this... 

Coupling the column from the GC to a mass spectrometer provides a very powerful combination, GC-MS, which can identify and quantify almost all the compounds in a complex mixture, such as an essential oil or perfume, by reference to libraries of mass spectra of known compounds. Careful investigation of the mass spectrum can be used deductively to determine a possible structure for an unknown material using fragmentation theories to identify sub-structural components of the molecule. Recent developments in benchtop mass spectrometers have brought a range of specialized MS techniques into the realm of GC-MS machines techniques such as chemical ionization and MS-MS are now available, which provide more information on individual sample components and allow better identification of unknown compounds. 

Rost J M 1998 Semiclassical s-matrix theory for atomic fragmentation Phys. Rep. 297 272-344... 

The intennolecular Hamiltonian of the product fragments is used to calculate the sum of states of the transitional modes, when they are treated as rotations. The resulting model [28] is nearly identical to phase space theory [29],... 

QET. quasi-equilibrium theory (of mass spectrometric fragmentation)... 

Theory of Electrophoretic Motion. The study of the mechanics of electrophoresis focuses on the basis of electric potential on the surface of an object, and the relation of the electric potential to the velocity of the particle. Whereas research has been generally limited to nonmolecular particles of weU-defined geometry and is not strictly apphcable to molecules such as proteins and DNA fragments, this work is useful for understanding the physics of electrophoretic motion. 

Each approach emphasizes different physical features observed in the fracture process. Either approach, under certain sets of conditions, may provide a satisfactory theory of fragmentation, although neither is apparently complete. 

Other methods for implementing the energy balance have been proposed and lead to moderate differences in predicted fragment size (Grady, 1982 Glenn and Chudnovsky, 1986). We contrast this earlier kinetic energy based theory with a more recent development in the following section. 

Energy-Horizon Theory of Dynamic Spall and Fragmentation... 

In the energy-horizon theory of fragmentation two physically reasonable... 

We note here that the fragment size predicted through the more recent energy-horizon theory ((8.30) or (8.34)) is between a factor of 2 to 3 smaller in nominal diameter than predicted through the earlier kinetic energy theory ((8.26)). This difference is more marked if a measure of fragment mass is... 

In both applications described above agreement is good, providing strong support for an energy balance theory of fragmentation. Note in particular that no recourse to an inherent fracture flaw distribution was needed. 

The present statistical study has been motivated by a desire to better understand and interpret dynamic fragmentation in mechanical systems. Applications include the blasting of rock with explosives or the fragmentation caused by the impact of a high-velocity projectile. For the reasons noted earlier it is difficult to verify the present statistical theory with experiments. Recently, however, support for the theories have emerged from rather diverse sources. 

Strong support for the statistical theory has been provided by computational dynamic fragmentation experiments (Holian and Grady, 1988). In... 

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