Buffer Of Limited Capacity Research Articles

Flow-shop problems with intermediate buffers

In this paper the following extension of the classical flow-shop problem is considered: Between each two successive machines a buffer of limited capacity is given in which jobs can be stored. After finishing processing on a machine, a job either directly has to be processed on the following machine or it has to be stored in the buffer between these machines. If the buffer is completely occupied the job may wait on its current machine but blocks this machine for other jobs. The objective is to determine a feasible schedule minimizing the makespan. To model such a problem setting, the classical disjunctive graph model for shop problems is extended. A tabu search procedure is described where neighborhoods based on an extension of the classical block approach theorem are used. Computational results for extended flow-shop benchmark instances are presented.

Optimal dispatching control of an AGV in a JIT production system

This paper deals with an FMS (Flexible Manufacturing System) in a JIT (Just-In-Time) production system. The FMS consists of m workstations, one dispatching station and a single AGV (Automated Guided Vehicle). Each workstation has an input buffer of limited capacity and its processing times are distributed stochastically. When the processing of a new component starts at the workstation, a withdrawal Kanban attached to it is sent to the dispatching station. The AGV chooses one from workstations whose withdrawal Kanbans are accumulated at the dispatching station, and conveys a component with a withdrawal Kanban from the dispatching station to the workstation. The main purpose of this paper is to find an optimal dispatching policy of the AGV that maximizes the long-run expected average reward per unit time. The problem is formulated as a semi-Markov decision process and an optimal dispatching policy is computed. Numerical experiments are performed to make several comparisons.

Decomposition of unreliable assembly/disassembly networks with limited buffer capacity and random processing times

An assembly/disassembly (A/D) network is a manufacturing system in which machines perform assembly and/or disassembly operations. We consider tree-structured systems of unreliable machines that produce discrete parts. Processing times, times to failure and times to repair in the inhomogeneous system are assumed to be stochastic and machine-dependent. Machines are separated by buffers of limited capacity. We develop Markov process models for discrete time and continuous time systems and derive approximate decomposition equations to determine performance measures such as production rate and average buffer levels in an iterative algorithm. An improved parameter updating procedure leads to a dramatic improvement with respect to convergence reliability. Numerical results demonstrate that the methods are quite accurate.

Modeling a Class of Flexible Manufacturing Systems with Reversible Routing

We model a flexible manufacturing system (FMS) as a closed queueing network with a set of stations, each with a local buffer of limited capacity. Based on the theory of reversibility as well as some known approaches in the studies of queueing networks with finite buffers, we derive product-form solutions to a class of such FMS networks that have reversible parts routing (a system with a centralized material handling station being one example). This class also includes a certain type of dynamic routing scheme. For systems with zero-buffer stations, we show that the solutions have product form even for nonexponential processing times.