This paper uses quantitative methods to estimate the size of the time buffer in lean operations controlled by the Theory of Constraints(TOC).The main focus of the operations system of TOC is the identification and man...This paper uses quantitative methods to estimate the size of the time buffer in lean operations controlled by the Theory of Constraints(TOC).The main focus of the operations system of TOC is the identification and management of constraints.To protect the constraints,they should be buffered with time buffers,which protecting the system’s output from disruptions and fluctuations.Despite the importance of time buffers,the approaches to identifying the size of the time buffer in literature are very empirical.In this paper,a queuing-theory based method is applied to calculate the time buffer sizes.It provides a mathematically exact expression for the coefficient of variation of waiting time for Markov queues.It then applies the concept of isomorphism to approximate the variance of customer waiting time in a general queue.Simulation experiments are conducted to verify the accuracy of approximation.展开更多
Manufacturing of ship piping system is one of the major production activities in shipbuilding.The schedule of pipe production has an important impact on master schedule of shipbuilding.In this research,the theory of c...Manufacturing of ship piping system is one of the major production activities in shipbuilding.The schedule of pipe production has an important impact on master schedule of shipbuilding.In this research,the theory of constraints(TOC) concept is introduced to solve the scheduling problems of piping factory,and an intelligent scheduling system is developed.The system integrates a product model,an operation model,a factory model and a knowledge database of piping production and can make the process planning and production scheduling automatically.In the paper,details of above points are discussed.Moreover,an application of the system in a piping factory,which achieves a higher level of performance as measured by tardiness,lead time and inventory,is demonstrated at the end of the paper.展开更多
文摘This paper uses quantitative methods to estimate the size of the time buffer in lean operations controlled by the Theory of Constraints(TOC).The main focus of the operations system of TOC is the identification and management of constraints.To protect the constraints,they should be buffered with time buffers,which protecting the system’s output from disruptions and fluctuations.Despite the importance of time buffers,the approaches to identifying the size of the time buffer in literature are very empirical.In this paper,a queuing-theory based method is applied to calculate the time buffer sizes.It provides a mathematically exact expression for the coefficient of variation of waiting time for Markov queues.It then applies the concept of isomorphism to approximate the variance of customer waiting time in a general queue.Simulation experiments are conducted to verify the accuracy of approximation.
文摘Manufacturing of ship piping system is one of the major production activities in shipbuilding.The schedule of pipe production has an important impact on master schedule of shipbuilding.In this research,the theory of constraints(TOC) concept is introduced to solve the scheduling problems of piping factory,and an intelligent scheduling system is developed.The system integrates a product model,an operation model,a factory model and a knowledge database of piping production and can make the process planning and production scheduling automatically.In the paper,details of above points are discussed.Moreover,an application of the system in a piping factory,which achieves a higher level of performance as measured by tardiness,lead time and inventory,is demonstrated at the end of the paper.
