Economic Optimization of Off-Line Inspection

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Joint work with
Tzvi Raz and Avraham Grosfeld-Nir

In this talk we explore the problem of determining the optimal inspection/disposition policy for a finite batch of items produced by a machine which is subject to random breakdowns. This talk will explore two separate, but related works.

In the first work we apply information theory to the problem of finding the first nonconforming unit in the batch at minimum cost. Two distinct but related aspects of this problem are treated: determining which units should be inspected and determining how many units should be sent for inspection at the same time. The solution is based on the principles of inspecting the units that maximize the reduction in the uncertainty regarding the location of the first nonconforming unit and of minimizing the cost per unit of uncertainty reduced. These principles are formalized by means of a series of theorems leading to an easy-to-implement algorithm for managing parallel inspection. This approach is successfully compared to the optimal solution obtained with dynamic programming and to other heuristics.

In the second work, we investigate situations in which the disposition of some of the units can be made without definitely identifying their status. The model considers three costs: the cost of inspection, the cost of rejecting a conforming unit, and the cost of accepting a nonconforming unit. We identify which units should be inspected and in which order so as to minimize costs. We place special emphasis on three different policies: the cost minimizing policy; the policy of perfect information, i.e. we insist on determining the quality of each unit; and the policy of zero-defects, i.e. we insist that all accepted units are known to conform to specifications, allowing the rejection of units of unknown quality.


  • Workflow Status: Published
  • Created By: Barbara Christopher
  • Created: 10/08/2010
  • Modified By: Fletcher Moore
  • Modified: 10/07/2016


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