The purpose of this paper is to analyse a special case of the non-pre-emptive single machine scheduling problem where the distinct due dates for each job are related to processing times according to the Equal-Slack rule. The scheduling objective is to minimize the sum of earliness and tardiness penalties. After determining some properties of the problem, the unrestricted case is shown to be equivalent to a polynomial time solvable problem, whereas the restricted case is shown to be NP-hard, and suggestions are made for further research.
A number of pull production systems reported in the literature are found to be equivalent to a tandemqueue so that existing accurate tandem-queue approximation methods can be used to evaluate such systems. In this study, we consider developing an exact performance evaluation model for a non-tandemqueue equivalent pull production system using discrete-time Markov processes. It is a periodically controlled serial production system in which a single-item is processed at each stage with an exponential processing time in order to satisfy the Poisson finished product demand. The selected performance measures are throughput, inventory levels, machine utilizations and service level of the system. For large systems, which are difficult to evaluate exactly because of large state-spaces involved, we also propose a computationally feasible approximate decomposition technique together with some numerical experimentations.
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