Far-field effects

Although values for TNT equivalency ranging from 0.3% to 4% have been observed, Brasie and Simpson recommend, for predictive purposes, conservative values for TNT equivalency as follows 2% for near-field, and 5% for far-field effects (based on energy), applied to the full quantity of fuel released. 

In short fiber composites, energy absorption mechanisms, such as interfacial debonding and matrix cracking, most often occur at the fiber ends (Curtis et al., 1978). The damage model proposed by Bader et al. (1979) assumes that short fiber composites fail over a critical cross-section which has been weakened by the accumulation of cracks, since the short fibers bridging this critical zone are unable to carry the load. In fatigue loading, sudden fracture takes place as a direct result from the far-field effect of the composite, rather than due to the near field of the crack tip... 

Satyavratam and Vedam also make the important point that the theory of underwater energy measurements was developed for relatively far-field effects, whereas the performance of commercial... 

No interference occurs between the scattered waves (far-field effects). This leads to a limit on the minimum value of Cl A., where C is the average interparticle clearance. However, most packed beds are made of large particles and can therefore be assumed to be above any such limit. 

De Braijne CH, Andriessen PAM (2002) Far field effects of Alpine plate tectorrism in the Iberian microplate recorded by farrlt related denudation in the Spanish Central system. Tectonophysics 349 161-184... 

Usually one distinguishes between "near field" and "far field" effects of radioactivity releases. Near field effects are observed close to the release source, as for example the nuclear power plant or nuclear waste storage facility. The dissolution of nuclear waste by rain or ground water is a typical near field problem. As the source is known, it can be controlled and its environment monitored. If the radioactivity exceeds permitted levels, access to the contaminated area can be restricted. Far field effects involve the behavior of radionuclides which have spread out of such a restricted area, caused either by nuclear power accidents and weapons tests or by leakage from nuclear power plants. 

In this paragraph we briefly describe some of the largest anthropogenic sources causing far field effects, i.e. nuclear weapons tests and nuclear power plant accidents. The cause of the releases is discussed in Chapter 19. Chapter 22 discusses both near and far field effects in further detail, particulary with regard to chemical properties liquid releases from nuclear power plants, dissolution of solidified nuclear waste and of fall-out particles, migration in the environment, and possible consequences. 

In convenAonal microscopy, the evanescent field is not uAlized instead, far field effects are employed, which results in the diffraction limit of resoluAon. 

For far field effects, that is, effects at large distances downwind from the release, the predicted consequences are highly sensitive to the dispersion and toxic effects models. As the distance from the release increases, the area impacted increases as the square of the distance. This increases the sensitivity of the consequences. For instance. Example 34 demonstrates that a change in probit concentration exponent from n = 2.75 to = 2.50 changes the predicted consequence dramatically— this is well within the variability range for published probit equations. 

Effects of Spin Coating and Substrate Interaction. Effects of spin coating and interactive interfaces on shear mechanical properties of ultrathin unannealed PEP elastomer films were discussed. It was found that a stressed boundary layer is formed, 7-10 Rg thick. This imexpected far-field effect for a polymer has recently also been observed for annealed PEP films (1), The degree of disentanglement depends strongly on the distance towards the interactive interface. Strained film surfaces were found to determine the film stability, and thus, can be responsible for spontaneous autophobicity. 

Special care should be taken particularly in the case of gas cloud explosions as the TNT method overpredicts near field effects and underpredicts far field effects. In some States the application of TNT equivalency is limited to overpressure values of 0.5 bar and other approaches are used for higher values, such as multienergy methods in which the separate effects from pressure and drag wind coming from different explosion cells are accounted for. However, the use of different TNT equivalencies in the near and far fields can overcome such a modelling deficiency. In general, TNT methods are considered suitable for greater distances from the source, for which the source mechanism is less important and such a simplified approach is more realistic and widely valid. 

Long Term Trends in Far-Field Effects of Marine Radioactivity... 

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