Donald D. Eisenstein

Bucket brigades on in-tree assembly networks

In a network of subassembly lines, balance becomes more difficult to achieve as it requires that all subassembly lines be synchronized to produce at the same rate. We show how to adapt the ‘‘bucket brigade’’ protocol of work-sharing so that balance emerges spontaneously. 2004 Elsevier B.V. All rights reserved.

Managing Hospital Inpatient Bed Capacity Through Partitioning Care into Focused Wings

We consider the partitioning of care types into wings from the perspective of a hospital administrator who wishes to optimize the use of a fixed number of beds that provide services for heterogeneous care types. The hospital administrator decides on the number of wings to form, the number of beds to allocate to each wing, and the set of care types to assign to each wing to maximize the total utility to the hospital. The administrator faces an inherent trade-off between forming large wings to pool demand and bed capacity, and forming specialized wings to focus on narrow ranges of care types. Specialized wings not only provide advantages from focused care but also allow the protection of beds for high-utility care types. We provide an optimization model for the wing formation decision and address the advantages of focus endogenously in our model. Using data from a large urban teaching hospital in the United States along with a national database, we report on a number of managerial insights. In particular, as the overall demand increases across all care types, wings are formed to reserve more beds for higher-utility types, which leads to higher overall hospital utility but also some disparity across types, such as increased hospital access for some and decreased access for others. Furthermore, overall bed occupancy decreases as the hospital is split into wings. However, if sufficient focus is attained, shorter lengths-of-stay associated with focused care may increase overall patient throughput. We also observe that when patients are willing to wait longer for admission, the hospital tends to form more wings. This implies that hospitals that garner longer waits can form more specialized wings and thereby benefit from focused care, whereas hospitals that cannot will tend to form fewer, if any, wings, choosing to pool demand and bed capacity.

Separating Logistics Flows in the Chicago Public School System

The central Chicago Public School warehouse was responsible for the distribution of supplies to 600 schools, including over

Managing Hospital Bed Capacity Through Partitioning Care into Focused Wings

10 million annually of engineering and educational supplies. The system was fraught with problems-deliveries were not made according to schedule, schools were hoarding inventories, and some schools were paying a premium for reliable service from third party suppliers. This paper reports how we improved this logistics system. We built a mathematical model of the system, validated our model using historical data, and used the model to evaluate the impact of potential changes to the system. Our recommended changes were implemented throughout the system. We report the impact on system performance. The redesigned system shows a dramatic reduction in lead times, a reduction in capacity requirements, and an overall reduction in system costs.

Building a Self-Organizing Urban Bus Route

We consider the partitioning of care types into wings from the perspective of a hospital administrator, who wishes to optimize the use of a fixed number of beds that provide services for heterogeneous care types. Patients of each care type request admission to the hospital stochastically, and if admitted, require a stochastic length-of-stay and provide the hospital some utility. If a bed is not immediately available, patients wait a random amount of time for admission, which may take place in a physical queue (as in an emergency room) or in a virtual queue (as in scheduled procedures). If their wait becomes excessive, they abandon the queue to seek care elsewhere. The hospital administrator decides on the number of wings to form, the number of beds to allocate to each wing, and the set of care types to assign to each wing in order to maximize the total utility to the hospital. The administrator faces an inherent trade-off between forming large wings to pool demand and bed capacity, and forming specialized wings to focus on narrow ranges of care types. Specialized wings not only provide advantages from focused care, but also allow the protection of beds for high utility care types. We provide an optimization model for the wing formation decision and address the advantages of focus endogenously in our model. Using data from a large urban teaching hospital in the United States along with a national database, we report on a number of managerial insights. In particular, as the overall demand increases across all care types, wings are formed to reserve more beds for higher utility care types, which leads to higher overall hospital utility but also some disparity across care types, as hospital access increases for some care types and decreases for others. Furthermore, as more wings are formed, overall bed occupancy in the hospital decreases. However, if sufficient focus is attained, shorter lengths-of-stay associated with focused care may increase overall patient throughput. We also observe that when patients are willing to wait longer for admission, the hospital tends to form more wings. This implies that hospitals that garner longer waits can form more specialized wings, and thereby benefit from focused care, whereas hospitals that cannot will tend to form fewer, if any, wings, choosing to pool demand and bed capacity.

Editorial: Interfaces at the Speed of the Internet

We built a control system to realize the idea of self-coordinating buses recently proposed by Bartholdi and Eisenstein. It has been extensively tested and by the end of 2012 will manage the most heavily-traveled bus route through the campus of the Georgia Institute of Technology in Atlanta, GA, USA. Here we review the idea, describe the architecture of a control system that implements it, and provide a snapshot of progress towards full implementation.

A Production Line that Balances Itself

Few organizations have been unaffected by the rapid change and availability of information technology (IT), especially the ubiquitous Internet. INFORMS has recently taken an important step to make a new kind of Internet service available with INFORMS Pubs Online (IPOL). IPOL (http://pubsonline.informs.org) provides the ability to access and perform a full text search of current INFORMS journals. As the new editor of Interfaces, I want to describe some of the recent Internet-based features and capabilities we have put in place for the journal.