Acoustic emission during powder compaction is observed to monitor the compaction process by the AE parameters. Discontinuous type AE produced during powder compaction is due to the successive periodic shear-yields that occurred in the compressed powder bed.
The AE cumulative count was proportional to the fractional volume compaction of the powder bed, and the AE cumulative count-compression strain relationship depends on the compressibility of the powder bed as in the compression stress-strain relationship.
The AE count rate relates to the behavior of particles undergoing compaction, and becomes lower as movement of particles is easier under low stress. These AE parameters are affected by the initial porosity of the bed, the powder property and the loading rate in powder compaction. The high frequency components in the frequency spectrum of the AE wave increase gradually as confined stress in the bed increases, and the frequency components also relate closely to the powder property and compression condition of the powder bed.

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It is already known that the structural strength among particles and the bulk density in a bin change greatly with different filling methods. This being the case, the frictional force acting on a rod inserted in a bin, in the beginning of discharge has to change greatly for each filling method. Therefore, the author investigated the frictional force on a rod inserted into the center in a bin. As a result, it was found that, in the case of the flow using bulk solids such as glass-beads and rapeseed, the frictional force in a dense bed achieved by peripheral feeding roughly doubled in comparison with that of a coarse bed achieved by central feeding. However, the frictional force for bulk solids such as sand did not generally change with each filling method. In this paper, an equation used to calculate the frictional force acting the insert rod was formulated.

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The three dimensional randomly packed systems of uniform-sized spheres were simulated by four kinds of algorithms. From a multi-fractal analysis, two different kinds of fractal dimensions in the packed system were obtained by the scaling method. The results show that the difference in particle packed structure, which cannot be clearly discriminated from the relationship between the average coordination number and the void fraction in a packed system, became discriminatable by using fractal dimensions either on long or short length scales. Therefore, fractal dimensions are useful to quantitatively express the packing structure in the particle packed systems.

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To investigate the flow characteristics with the steady state pneumatic transportation of solids in horizontal pipes at low air velocities, in this paper, instantaneous photographs of solid flow patterns were taken with a camera simultaneously operated with a storoboscope. The experimental results were as follows: solids tend to settle out along the bottom of the pipe and form dunes at a periodic interval. The height and the length of each dune under such condition is related to the solids-gas flow ratios, as well as to air velocity. However, when the solids-gas ratios are more than 10, these values become constant independently of the solids-gas ratios. On the other hand, the angle of slope, and the pitch length of each dune are independent of the extent of air velocity and solids-gas ratios.

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