Particles rounded

In the three matrix elements shown in the bottom half of Fig. 13.14, there appear to be less pronounced differences between spheres and nonspherical particles. Perry et al. pointed out that near the forward direction S 34/511 is rather sensitive to the parameters of the size distribution, while measurements for both kinds of particles—rounded and cubic—agree quite well with calculations. Similar agreement between calculations for spheres and spheroids was noted by Asano and Sato (1980). This combination of sensitivity to size distribution and insensitivity to shape might be put to good use in particle sizing. 

Particle shape is of the greatest importance for agglomeration. Typical characteristics are particle roundness or the general overall shape and surface roughness. For some binding mechanisms and/or agglomeration methods, the particle shape is the most decisive particle characteristic. 

The equivalent diameter is sometimes defined as the diameter of a sphere of equal volume. For fine granular materials, however, it is difficult to determine the exact volume and surface area of a particle, and Dp is usually taken to be the nominal size based on screen analyses or microscopic examination. The surface area is found from adsorption measurements or from the pressure drop in a bed of particles, and then Eq. (28.1) is used to calculate < >,. For many crushed materials 4>j is between 0.6 and 0.8, as shown in Table 28.1, but for particles rounded by abrasion d>j may be as high as 0.95. 

The initial cell model in this study is a rigid particle rounded by a thin shell, representing a cell with membrane, with homogeneous, lossy and dispersive dielectric properties for each layer [7], This model allows us to determine the response of electric fields on the entire cell, including plasma and intracellular membrane. 

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