M.Sc Student | Bendavid Illana |
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Subject | Economic Optimization of Off-Line Inspection in a Process that Produces also Non-Conforming Units when In-Control and also Conforming Units when Out-of Control |

Department | Department of Industrial Engineering and Management |

Supervisor | Professor Yale Herer |

A finite batch of units is
produced by a process subject to random failures. This process starts from the
IN state and may shift, while producing a unit, to the OUT state. We consider
the case that inspection is conducted after all the units of the batch have
been produced and when the production order of the units is preserved. Until
now, it was assumed that in the IN state, the process produces only conforming
units and in the OUT state, it produces only non-conforming ones. In our
research we consider that in the IN state the process may also produce
non-conforming units and in the OUT state, it may also produce conforming ones.
We develop an optimal inspection/disposition policy that finds which units to
inspect and how to dispose of uninspected units in order to minimize the total
expected cost, which includes inspection cost and penalty costs due to
classification errors. This optimal policy is obtained by formulating the
problem and solving it as a dynamic programming problem. Although optimal, this
solution is limited since the computational complexity
of the dynamic programming algorithm is *0*(3* ^{n}*). In addition to
the optimal policy we explore four heuristic policies. We conduct an extensive
computational study on the optimal policy to check the influence of the model
parameters on several aspects of the optimal solution. We then conduct
computational studies on the heuristic policies to check their performance
relative to the optimal policy and also to compare between the different
heuristic policies in cases for which we were not able to compute the optimal
policy.