Masanori Kodama

Reliability Considerations for a 2-Unit Redundant System with Erlang-Failure and General Repair Distributions

This paper considers the case of a 2-identical-unit redundant system with Erlang-failure and general repair distributions. Two cases are considered: 1) the failure of each unit is independent of the other; 2) when one unit fails, the failure distribution in the other unit changes. The Laplace transforms of the distribution of time to system failure and the explicit formula for the mean time to system failure are derived.

Mission Reliability for a 1-Unit System with Allowed Down-Time

This paper considers a 1-unit system; the unit is repaired upon failure. The failure and repair rates need not be constant. The system fails if the unit is not repaired within a fixed time, or if the number of failures during the mission exceeds a fixed number. As a special case, that number is allowed to be ``infinite. The Laplace transforms of the reliability and mean time to system failure are derived; they are not easily solved. The special case of constant failure and repair rates is treated. The results are compared with those of Calabro.

Sensitivity analysis of an economic order quantity for dynamic inventory models with discrete demand

We study a sensitive analysis of probabilistic inventory problems of multi-period in which demand is a discrete random variable. In the typical inventory model with general demand pattern, we presented a method to decide an optimal policy, which enables us to investigate the effect of the variance of purchasing cost, holding cost and shortage cost on the economic ordering quantity in the inventory system of N-period. Moreover, we compare the optimal policies of inventory examples where demand is a binomial or Poisson random variable.

An application of dynamic probabilistic inventory models with piecewise cost functions

It is shown how to use a mathematical model of the probabilistic inventory problems with piecewise cost functions. An example is presented and various properties in this model are applied to this. We give some sufficient conditions which are able to deal with treatments on an optimal policy.

Some probabilistic inventory problems with various demand pattern

Abstract We consider the probabilistic inventory models with various partial returns and additional orders. There are the ordering costs, holding costs and penalty costs in the models. Specific values of the variables that minimize the total expected costs in one stage are found. Mathematical generalization of these problems is made and various properties are discussed.

Reliability analysis of a 2-dissimilar units redundant system with erlang-failure and general repair distributions

Abstract This paper considers the case of two dissimilar unit redundant system with Erlang-failure and general repair distributions. Three cases are considered. (1) warm stand-by redundancy; (2) warm stand-by redundancy with priority; and (3) parallel redundancy in which case the failures of the units are not statistically independent. In models (1) and (2), the failure of each unit is independent of the other. The Laplace transforms of the reliability and the explicit formula for the mean time to system failure are derived.

Dynamic programming on the probabilistic inventory problems with multiple piecewise cost functions

A mathematical model of the probablistic inventory problems with piecewise cost functions is presented and various properties are discussed. And also some sufficient conditions on cost functions are found to ensure simple treatment on a optimal policy.

On a Multichannel Queueing System with Semi-Ordered Entry

Abstract This paper deals with a multichannel queueing system with semi-ordered entry. The transient and stationary solutions about this system are obtained numerically. The model described here has wide applications; for example, to production systems with closed-loop conveyors.