TY - GEN
T1 - On cycle time approximations for the failure prone G/G/m queue
AU - Kim, Woo Sung
AU - Morrison, James R.
PY - 2011
Y1 - 2011
N2 - As high tech manufacturing systems are very expensive, it is especially important to operate them efficiently. To determine if a system is operating efficiently, one must evaluate its performance. One efficiency issue in practical systems is that tools are not perfectly reliable; tools may fail. Approximate queueing formulae are often used to model system performance such as mean cycle time. While many approximations for failure prone tools have been proposed, the theoretical justification for such formulae is sometimes insufficient. There are few solutions for the failure prone queue, so it can be hard to justify approximation formulae theoretically. In particular, approximation formulae can have significant error in low loading because most focus on heavy traffic. By studying the G/G/m failure prone queue in low loading, we can determine if approximation formulae work well. Assuming Poisson arrivals, exponential service and low loading, we can model the system as an absorbing Markov chain. Using renewal theory, we derive an exact solution for mean cycle time of the system in low loading. Based on our results, we can test common mean cycle time approximations and compare them in low loading. In this paper, we test two common approximations. The result is that one is more accurate than the other. As the number of servers increases, there is greater accuracy difference between the two.
AB - As high tech manufacturing systems are very expensive, it is especially important to operate them efficiently. To determine if a system is operating efficiently, one must evaluate its performance. One efficiency issue in practical systems is that tools are not perfectly reliable; tools may fail. Approximate queueing formulae are often used to model system performance such as mean cycle time. While many approximations for failure prone tools have been proposed, the theoretical justification for such formulae is sometimes insufficient. There are few solutions for the failure prone queue, so it can be hard to justify approximation formulae theoretically. In particular, approximation formulae can have significant error in low loading because most focus on heavy traffic. By studying the G/G/m failure prone queue in low loading, we can determine if approximation formulae work well. Assuming Poisson arrivals, exponential service and low loading, we can model the system as an absorbing Markov chain. Using renewal theory, we derive an exact solution for mean cycle time of the system in low loading. Based on our results, we can test common mean cycle time approximations and compare them in low loading. In this paper, we test two common approximations. The result is that one is more accurate than the other. As the number of servers increases, there is greater accuracy difference between the two.
KW - Absorbing Markov chain
KW - Failure prone tool
KW - Performance evaluation
KW - Queueing approximation formula
UR - http://www.scopus.com/inward/record.url?scp=84856545812&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84856545812
SN - 9781457708350
T3 - International Conference on Control, Automation and Systems
SP - 1558
EP - 1563
BT - ICCAS 2011 - 2011 11th International Conference on Control, Automation and Systems
Y2 - 26 October 2011 through 29 October 2011
ER -