Algorithms are presented for feature extraction of geometrical shape of particles. The system consists of microcomputer, and an image scanner which scans the micrograph of particles and transmits the compressed image data. Methods for shape analysis are 1) calculation of fundamental particle shape parameters (Feret diameter, area, perimeter, first moment, second moment), 2) fractal analysis, 3) opening method and 4) separation of circular primary particles from an agglomerate. Connectivity of particle boundary is recognized for five cases (continuation, termination, creation, split and merge), and fundamental shape features are calculated according to it. Validity and accuracy of these methods are examined by comparing the calculated and theoretical shape parameters for standard figures. A new index is proposed for the structuring element number of two-dimensional particle shape in opening analysis. These methods are applied to the shape analysis of agglomerated aerosol particles generated from an electric furnance and by CVD method, and it is shown that the fractal dimension as a particle distribution is useful for quantitative description of shape feature.
A Mie laser radar was used for observing diffusion of exhaust gases from motorcars running on a straight road over a flat terrain. Pointing the laser radar horizontally to the road at a right angle, time-range distribution patterns of aerosol concentration were obtained; this showed downwind transport of aerosols. This aerosol distribution pattern reflects the traffic flow intervals which is controlled by traffic lights at the intersections. Because of the intermittency, instantaneous concentrations of exhaust gases, including aerosols, are possibly sometimes higher than those averaged over long time. It is necessary to take into account the traffic intermittency when constructing models for simulating diffusion and reaction processes of exhaust gases.
To calibrate instruments using polystyrene particles as a reference size material, it is necessary that the sizes of polystyrene particles are measured accurately, however, we have sometimes experienced that there are differences between manufacturers' nominal sizes and actual measurement values. Size measurement by Transmission Electron Microscope (TEM) photographs has commonly been used, but, it has not been under proper control. Magnification errors, growing or shrinking of particles have been among those problems. We have developed a measuring method of particle size, and in this paper, the method of measuring the particle size of polystyrene particles by a TEM and exact sizes of polystyrene particles are reported.