Mitsuo Yamashiro

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.

A system where the number of servers changes depending on the queue length

In this note, the system is analyzed in the steady state by assuming that the number of servers change depending on the queue length. In the case of two servers, it is assumed that the service abilities of each server differ. The mean number of customers in the system and the mean queue length of customers are derived as the characteristic values of the system.

A method for solving fuzzy De Novo programming problem by genetic algorithms

Abstract This paper investigates how to solve optimal design problem of system reliability with fuzzy goal that is formulated as De Novo programming problem by genetic algorithms (GA). We propose an implementation of the GA for solving De Novo programming problem with fuzzy goal. The proposed approach has the flexibility that we can consider the fuzziness based on the DMs subjective judgement and the DM can design the system by distributing appropriate resources to each constraint.

The median for a L-R fuzzy number

Abstract When a L-R fuzzy number is adopted as fuzzy data in fuzzy numbers, as this number shows the general model function containing trapezoidal and triangular fuzzy number it has been applied to various problems. In this study, the median of the L-R fuzzy number is proposed and indicated by using some numerical examples.

A repairable system with N failure modes and K standby units

Abstract This paper presents a repairable system with N failure modes and K standby units. Laplace transforms of state probability for such a system are obtained by using the supplementary variable method. Two particular cases are considered.

A repairable system with partial and catastrophic failure modes

Abstract In this paper, we deal with a repairable system with partial and catastrophic failure modes. Laplace transforms of state probability for such a system are obtained by using the supplementary variable method.

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.

A repairable system with N failure modes and one standby unit

Abstract In this paper, we deal with a repairable system with N failure modes and one stanby unit. Laplace transforms of state probability for such a system are obtained by using the supplementary variable method. A particular case is considered.

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.

A decision-making model for optimal production rate in economic volume-flexibility production system

Abstract The classical economic production lot size (EPL) model assumes a predetermined and inflexible production rate and a continuous demand of customers, and does not take raw materials inventory cost into account. In this paper, a production system with volume flexibility is considered which procures raw materials from suppliers and processes them to convert to finished products. We develop a decision-making model for optimal production rate selection in a volume-flexible production system, where finished products are delivered periodically at a fixed quantity with a fixed interval of time. In this model, production rate is perceived as a decision variable and unit production cost becomes a function of production rate. We develop a pragmatic computation approach to solve the proposed model for special unit production cost functions. Some observations are made for optimal production rate analysis. Finally, we conduct a numerical study to illustrate the solution. Also, a set of data with ten problems is tested and compared.