The spatial distributions of particles for each reference shape or size can be measured using the Multiplexed Matched Spatial Filtering Method. In this method, auto-correlation peaks which determine the shape and size of particles are moved with the movement of input particles. Under its principle, it is experimentally clarified that the behavior of input particles can be measured by the loci of auto-correlation peaks, and the velocity of particles for individual shape or size can be determined by the movement of auto-correlation peaks. The fundamental research and experimental results are shown in this paper.
The usual liquid immersion method is modified for accurate measurement of refractive index of polydisperse fine particles. Instead of the direct observation of scattered light intensity, we developed new optical arrangement based on a multi-line laser and an optical multichannel analyser. It was applied to the measurement of monodisperse Silica sphere and polydisperse Allophane particles. The liquid immersion method, which was conventionally used to measure the refractive index, determine the rafractive index by observing the change of the scattered light intensity from fine particles immersed in dispersion liquid by eyes, on the other hand the modified method by measuring the scattered light intensity from fine particles irradiated with a multi beam laser by an optical multichannel analyzer. It was eatimated that the refractive indices determined by the modified method were mostly equivalent to the specific values of Silica particles and refractive indices of Allophane particles found in the references.
Numerical and experimental investigations are carried out to characterize the pressure drop of a separator-type HEPA filter, by studying the pressure drop of a filter element with a different separator height. The element for pleated filter is assumed to have square cross-section bounded by the separator walls, consisting of two square flow channels separated by the filter medium. The total pressure drop was numerically calculated and compared with the experimental pressure drop measured with two dimensional model filter elements. It was found that, for a given configuration of filter element, there exists an optimal separator height that gives the minimum pressure drop. The pressure drop through filter medium determines the total pressure drop of the filter at a large separator height, while at a small separator height the friction in the flow channel dominates the total pressure drop.