This research focuses on the effect of setup time on lot sizing. The setting is the Capacitated Lot Sizing Problem (the single-machine lot sizing problem) with nonstationary costs, demands, and setup times. A Lagrangian relaxation of the capacity constraints of CLSP allows it to be decomposed...

This paper concerns the modeling of low inventory lines. Currently, most models assume that processing times are independent. We consider the differences in behavior of workers in low- and high-inventory production lines. Using a laboratory experiment we show that workers speed up when they are...

In practice, most multi-echelon inventory systems are managed using adaptations of single location methods. This paper shows that such methods can be dramatically inferior to methods designed to take advantage of a system's structure. This is especially true in repair parts inventory systems...

This paper investigates a multi-item, multi-level production scheduling problem with linear costs and production and inventory constraints at one key facility. Two multi-item problems---one in which the constraint was on shipping capability and one in which there was a final stage bottleneck...

This research addresses a system of flexible worker assignments in a setting where there are more workers than machines. When organized using this system, a production line balances itself by shifting the workloads continuously and automatically in response to changes in the state of the system....

The problem of determining both lot sizes and repeating sequences for N products on one facility is difficult due to the combinatorial and continuous nature of the problem. The work that has been done on the problem has made various assumptions ("zero-switch rule" or "equal lot size," for...

In this paper we present a heuristic method, based on Lagrangian relaxation, for multilevel lot-sizing when there is a single bottleneck facility. A series of Lagrangian relaxations (one for each item in the product structure) is imbedded in a branch and bound procedure. The objective is to find...

In this Note we present an alternative formulation to the MRP lot sizing model of Steinberg and Napier (SN) (Steinberg, E., H. A. Napier. 1980. Optimal multi-level lot sizing for requirements planning systems. Management Sci. 26 (2) 1258--1271.). The alternative is more parsimonious and the...

In this Note, we address the issue of safety stock considerations in an MRP environment through the use of a single identical component as a replacement for a set of multiple components. We indicate where the results reported by Collier (Collier, David A. 1982. Aggregate safety stock levels and...

Customer service has assumed strategic importance in most manufacturing environments. Corporate reputations often depend on how reliably promised lead times are met. A goal of filling orders within a service window of T time units is often encountered in practice. This goal ignores the...