ABSTRACT
One often forgets the vast extent of particulate material utilized by society. For example, 100 million tons of steel produced a year implies something like 400,000,000 tons of ore was dug, crushed, processed, and an equal amount of overburden removed. A new method of quantitatively characterizing particles was developed independently by four investigators in the late 1960s. To characterize a particle, one takes the projected area of the particle and records points on the particle outline. Think of a silhouette of a particle with the maximum projected area, taking discrete points along that silhouette edge. Besides Fourier there are other orthonormal functions that can be used to analyze the particle's silhouette. Among the more familiar are the Walsh and the Haar. Each of the orthonormal functions yields a series of coefficients. These coefficients are linearly related to the coefficients of every other orthonormal function.
