This paper addresses the problem of order-picking in a rectangular warehouse that contains crossovers only at the ends of aisles. An algorithm is presented for picking an order in minimum time. The computational effort required is linear in the number of aisles. The procedure has been implemented on a microcomputer A 50-aisle problem requires only about 1 minute to solve.

This paper is concerned with an integer progranming characterization of a cut i n a network. provides a fundamentat equivalence between directed pseudosymm e t r k netuorks and undirected netuorks. I t aZso i d e n t i f i e s a ctass of problems which can be sotved as minimum cut probtems on a network. This chaxacteAzation

A fundamental problem of cyclic staffing is to size and schedule a minimum-cost workforce so that sufficient workers are on duty during each time period. This may be modeled as an integer linear program with a cyclically structured 0-1 constraint matrix. We identify a large class of such problems for which special structure permits the ILP to be solved parametrically as a bounded series of network flow problems. Moreover, an alternative solution technique is shown in which the continuous-valued LP is solved and the result rounded in a special way to yield an optimum solution to the ILP.

No abstract

This paper addresses duration-of-stay-based shared storage policies for a unit load warehouse. We show that, for single command storage and retrieval, shared storage policies based on duration of stay of individual unit loads have the potential to significantly decrease travel time. An optimal storage policy with respect to travel time and storage space is developed for systems with balanced input and output. Based on the same principles, two heuristic policies are developed for more complex systems. Simulation results are provided which compare travel times for dedicated storage, random storage, turnover-based storage classes, and duration-of-stay-based storage classes.inventory/production, materials handling

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The n most vital links of a flow network are defined as those n arcs whose simultaneous removal from the network causes the greatest decrease in the throughput capability of the remaining system between a specified pair of nodes. These n arcs are shown to be the n largest capacity arcs in a particular cut. A solution procedure is developed which involves sequentially modifying the network so as to make this cut eventually become the cut with smallest capacity. An algorithm with computational results is presented.

We consider the problem of finding locations for new facilities in an imbedded tree network with respect to existing facilities, with upper bounds imposed on distances between all pairs of facilities. We obtain necessary and sufficient conditions, termed separation conditions, for the distance constraints to be consistent. We find string models useful in obtaining insight into the conditions. These separation conditions involve shortest paths through an associated network that has as arc lengths the upper bounds on pair-wise facility distances. Also, we give an algorithm that constructs a feasible solution to the distance constraints if one exists. As an application of the separation conditions, we solve a multifacility minimax location problem. Most of the results obtained in this paper are also true when distances are Tchebyshev between facilities in Rp, p ≥ 1, or are rectilinear between facilities in R2. Further, the results of this paper should be useful in addressing “nonlinear” minimax location problems and multiobjective, multifacility location problems.