Scheduling resources to avoid deadlock in a manufacturing system has been studied extensively over the past decade. Previous work developed sufficient conditions to avoid deadlocked states.What distinguishes the different approaches is the number of nondeadlocked states that are allowed by the application of the method. This is an important consideration since in all the methods these non-deadlocked states are those with high resource allocation. This paper presents both sufficient and necessary conditions to determine deadlocked states in a manufacturing system. Several examples showing the applications of the theory arc presented and are compared with other methods.

A deadlock avoidance algorithm for flexible manufacturing systems containing both multiple capacity resources and mixed choices in part routing is presented. The method determines whether moving a part to its next step is safe, unsafe, or undetermined.That classification is linear in complexity. Undetermined part movements are further analyzed using another procedure, which attempts to empty the system virtually to determine whether the move is safe or not. It is polynomial in complexity. An example is provided to illustrate how the method can be applied.

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In modern automated production lines, it is common to connect adjacent machines with buffers. Since these buffers are mechanical devices, they are prone to failure. Previous research concerning the steady-state analytical modeling of serial transfer lines assumed that buffers are completely reliable. This paper considers the unreliable buffer and presents a model of the serial transfer line incorporating this concept. A decomposition technique is developed for the general serial transfer line with unreliable buffers, and an algorithm for computing the solution of the model is presented.Index Terms-Discrete-event systems, manufacturing systems, performance modeling, unreliable buffer. R n2n ; i = 1; 111; q, we denote the convex hull of this set (convex matrix polyhedron in R n2n ) by A = conv(A1; 1 11; Aq).

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