Yasunobu Yuasa

An experimental study on the relationships between compressibility, fluidity and cohesion of powder solids at small tapping numbers

Abstract Measurements of cohesion and fluidity are important for industrial control of the properties of powder solids. The compressibility, the fluidity and the cohesion of powder solids are investigated by the method of tapping. In the traditional reports, intervals of N, the tapping number, of 10, 20, 30, 50, 100, … have been widely used. In particular, for powder solids having a small rather than a large particle diameter, the degree of volume reduction C should change significantly with change in tapping number. C decreases gradually if N exceeds a certain value and then does not change when N is increased beyond the tapping number limit. In this report, therefore, C is measured at small intervals of tapping number (1 or 2). A linear relationship between N/C and N is obtained as shown in Fig. 3 as well as from the traditional results and no unusual phenomenon was observed. It is found, moreover, that Kawakitas formula relating to compression is applicable and a comparison between the various kinds of powder solids can be made by physical interpretation of the constants in his formula.

Repair system where the repairmen change depending on the failed machines

In this study, the repair system of the machines having multi-input sources is analyzed in the steady state by assuming that the repairmen change is dependent on the failed machines. In the cases of two and three repairmen, it is assumed that the service abilities of each repairman differ. The mean number of failed machines and the mean waiting failed machines are derived as the characteristic values of the system.

Parallel-series and series-parallel redundant systems consisting of units having two kinds of failure rates

Abstract In this study, four parallel-series and series-parallel redundant systems consisting of units having two kinds of failure rates are considered and the reliability of each system and MTBF (Mean Time Between Failures) are evaluated. Next, as a special case of the systems in this study, MTBF relating to each system consisting of four units are evaluated. The large and small relations of the MTBF between systems are made clear.

Comparison of MTBF in the parallel string configuration and the quad configuration systems

In this study, four redundant systems having the parallel string configuration and the quad configuration consisting of 2n identical units are considered and the reliability of each system and MTBF (Mean Time Between Failures) are evaluated. Next, as the special case of the systems in this study, the case of four units corresponds to the Keenes system and MTBF of each system agreed with his results. Further, as the results evaluated MTBF relating to each system consisting of 6, 8 and 10 units, the large and small relations of the MTBF between systems are made clear.

Penetrating properties into a powder solids layer when various weights are dropped on to a cylindrical rod from a fixed height

Abstract Experiments are carried out in which weights fall freely from a fixed height on to a cylindrical rod which penetrates into a powder solids layer of styrol resin or glass beads. The relationships between the penetrated depth and the weight or the falling height are considered. Further, an emery paper is pasted on the bottom of a cylindrical rod and the effect of its roughness on the penetrated depth is investigated.