An echelon inventory-based single-stage cost function for a two-station tandem system

We propose an alternative cost-accounting function for inventory control problems on a make-to-stock setting. Our proposal is based on observing that the traditional holding and backlog parameters introduce some odd short term distortions on the inventory state space. Our single-stage cost function accounts for echelon inventories and possesses a pair of cost parameters for each echelon inventory variable, depending on whether it is positive or negative. With the modified cost-accounting function, we study a twostation tandem system producing a single product, and investigate how it compares with the performances obtained with the usual single-stage cost function. The results available so far show that the optimal policies approach a multi-echelon base stock structure for each machine. Also, the service levels achieved are better under the modified function without increasing the levels of finished goods inventory.     

构筑支持企业可持续发展的四大梯队

企业及其可持续经营与发展是构成社会可持续发展的系统要素.从 根本上说,企业可持续经营与发展依赖于企业自身具有梯队结构和内容的支持系统,主要包括1.产品技术梯队-企业可持续经营与发展的核心;2人力资源梯队-企业可持续经营与发展的源泉;3.管理机制梯队-企业可持续经营与发展的保证;4.领导能力梯队-企业可持续经营与发展的关键.     

A NOTE ON ARMA PARAMETERISATION*

This paper considers the relationship between ARMA parameterisations of models for y(t) and Ay(t), where A is invertible and y(t) is a vector time series (t = 0,±1,…). An ARMA model for the transformed series Ay(t) may have fewer parameters than a model for y(t). This paper shows that such a saving is illusory because the apparently saved parameters are exactly balanced by the number of new parameters appearing in A.