An analytical investigation of the scheduling problem for capacitated re-entrant lines

The basic definition of the re-entrant line ignores completely the effects and complications arising from additional operational issues like the finite buffering capacity of the system workstations/production units. Yet, as the semiconductor industry moves to more extensive modes of automation, the explicit characterization and control of these additional operational features is of paramount importance for the robust and stable operation of the entire system. The work presented undertakes an analytical treatment of the scheduling problem of capacitated re-entrant lines, providing (i) a formal framework for the systematic integrated modeling of the system behavior and the super-imposed operational control logic, (ii) an analytical formulation of the scheduling problem in the context of this framework, and (iii) a qualitative characterization of the structure of the optimal scheduling policy. The proposed methodology is exemplified through application on a small system configuration, and while it suffers from a very high computational complexity, it is expected that the obtained characterizations will provide valuable analytical insights for developing pertinent approximating techniques