The optimal allocation of buffers in serial production systems is one of the
oldest and most researched problems in Industrial Engineering. In general, there
are three main approaches to the buffer allocation problem when the objective is to
maximize throughput. The first is basically a systematic trial and error procedure
supported either by discrete event simulation or analytical models. A second
approach is to allocate buffers based on general design rules that have been
established in the research literature through experimentation. And the third
approach is to apply a buffer allocation optimization algorithm to a specific
production line. All these approaches have limitations and could be time and
resource consuming. Additionally, most of the existing research on buffer
allocation only considers production systems modeled with an infinite supply of
raw materials before the first workstation and an unlimited capacity for finished
goods after the last workstation. In reality many production systems are designed
as closed systems where an interaction between the last and the first workstations in
the line is present. In a closed production system, there is a finite buffer after the
last workstation and the number of "carriers" holding jobs that move through the
line is fixed.
The objective of this thesis was to develop efficient heuristic algorithms for
the buffer allocation problem in closed production systems. Two heuristics for
buffer allocation were implemented. Heuristic H 1 uses the idea that highly utilized
workstation stages require any available buffer more than sub-utilized stages.
Heuristic H2 uses information stored in the longest path of a network representation
of job flow to determine where additional buffers are most beneficial.
An experiment was designed to determine if there are any statistically
significant differences between throughput values with buffer allocations obtained
with a genetic algorithm, also developed in this research, and through puts with
buffer allocations generated by Hi and H2. Several types of closed production
systems were examined in eight different test cases. No significant differences in
performance were observed. The efficiency of the heuristics was also analyzed. A
significant difference between the speeds of Hi and H2 is found.
The analysis performed in this research indicates that heuristic H2 is
sufficiently effective and accurate for determining near optimal buffer allocations in
closed production systems. / Graduation date: 2005
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/30021 |
| Date | 28 April 2005 |
| Creators | Vergara Arteaga, Hector A. |
| Contributors | Kim, David S. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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