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The present study deals with an optimal inspection policy for a scale where the inspection for a scale is conducted when the elapsed time since the previous inspection or adjustment reaches T (> 0) for the purpose of detecting its uncalibrated or inaccurate state and where its uncalibrated state can also be detected empirically or accidentally. The design variable under such a policy is T (> 0). The expected cost per unit of time is formulated as an objective function to be minimized. The conditions under which an optimal inspection scheduled time T exists are then clarified. Numerical examples are presented to illustrate the theoretical underpinnings of the proposed formulation. The proposed model is also compared with the conventional one to show that the proposed model can reduce the cost.

This study proposes a new modified discrete preventive maintenance policy where failures of a system can be detected only by inspections and be fixed by minimal repairs. The maximum number of minimal repairs allowed to the system is, however, a prespecified integer, N. Under the proposed policy, inspections are conducted at times T, 2T, ...(T>0) to detect and fix failures by minimal repairs, and the whole system is preventively replaced by a new one when the cumulative number of failures detected becomes equal to an integer, k or more. The expected cost per unit time is formulated under the proposed maintenance policy. The existence of an optimal integer k=k* which minimizes the expected cost is then shown. Numerical examples are also presented to illustrate the theoretical underpinnings of the proposed formulation.

To make a theoretical comparison between two scale‐inspection and warranty policies for weight‐quality, one practical and the other theoretically grounded.

Comparison is made in a Stackelberg game framework considering the consumer's as well as the manufacturer's viewpoint.

The practical policy is more profitable for the manufacturer than the theoretical policy in many cases.

The study confines itself to scale‐inspection and warranty policies, but the underlying approach used in this paper can also be applied to other topics.

The proposed model can also provide a lower bound for the warranty.

The study compares a practical policy with a theoretical one from both the consumer's and manufacturer's point of view.

At a store of chain retailers in Japan, a manager must select some new products from the list offered by the head office and, at the same time, he must determine which products should be replaced by the new products he selects. For the purpose of supporting such a decision, the authors have already proposed a new brand monitoring strategy for a certain category at a retail store and provided its mathematical model. Reviews their model emphasizing its practical aspects, and applies their model to actual data on grocery products collected from a convenience store with a discussion on the characteristics of their model.

There exist some reliability models whose performances increase by partitioning them into parts. Such a typical model is the basic inspection policy in which an operating unit is checked at suitable times for a finite time span and its failure is detected. This paper applies the concept of the basic inspection policy to five models: back‐up for hard disk, checkpoint for double modular redundancy, job partition, garbage collection, and network partition. The performances of each model are analytically evaluated.

The present study proposes two types of periodical inspection policies for a scale which weighs products in the final stage of manufacturing some specific products, such as chemical products. The scale is inspected at time iT(i=1,2, … ). Under ModelI, an inspection operation involves detection of a scale malfunction or inaccuracy as well as an adjustment activity. Under ModelII, an inspection is conducted only to detect a scale malfunction. If a scale malfunction is detected, an adjustment activity follows. For each model, the fraction defective and the long‐run average cost are formulated. We then examine the existence of an inspection interval T_α which makes the fraction defective under a prespecified value α (0< α <1). An economical inspection interval T^* minimizing the long‐run average cost is also discussed.