Dean Uyeno

PASSIM: a discrete-event simulation package for PASCAL

This paper describes a set of procedures that can be used to construct discrete-event simulation models in PASCAL. The set of procedures is called PASSIM for PASCAL-based SIMulation The approach combines scheduler and entity concepts from GPSS with pointer- based data structures and control structures from PASCAL. The procedures employ only standard PASCAL statements to ensure portability.

RESOLVING SPLITS IN LOCATION/ALLOCATION MODELING: A HEURISTIC PROCEDURE FOR TRANSIT CENTER DECISIONS

A heuristic procedure is developed to assign buses to transit centers (garages) in such a way that all the buses on a particular route are assigned to a single transit center. This research builds on an optimal mixed integer programming location/allocation model that splits the bus assignments when capacity limitations were reached at a transit center. The heuristic procedure adopts a two-step process: namely, assignment of all buses of a route to a unique transit center, then switching of routes to alternative transit centers to enforce capacity limitations. The procedure is shown to still provide cost savings over current locations and allocations for the Vancouver Regional Transit System (VRTS), Canadas largest urban transit network.

A simulation-based methodology for optimization of ambulance service policies

Abstract A simulation-based methodology for the evaluation of the emergency ambulance system in the Vancouver, Canada, metropolitan area has been created. Outputs from the simulation of the system are utilized in the creation of the objective function of a branch and bound optimization procedure. The solutions are thus obtained at a significantly lower cost than if only simulation were used. The final solutions were verified by simulation runs.

Efficient search procedures for extreme pollutant values.

Extreme pollutant values are of great interest in water quality monitoring because of their frequent toxicological significance. The principal barrier to the detection of these values, however, is the cost of extensive and comprehensive monitoring. This paper demonstrates an efficient method to determine the maximum sample measurement from a finite set of sequential samples without explicitly testing them all. It is assumed that the process of sample measurement is distinct from collection and has higher costs. It is further assumed that the measurements have high positive autocorrelation.A methodology is presented based on a common industrial testing procedure referred to as composite sampling—the physical pooling or compositing of a set of sequential samples before measurement. A method known as primary first order compositing (PFOC) was found to be superior to the traditional technique of random sampling, particularly if small composite sizes are utilized.

TRANSIT CENTRE LOCATION - ALLOCATION DECISIONS

A computationally feasible methodology to locate, size, and determine the number of transit centres (bus barns or garages) for an urban transit system is described. This methodology, known by the acronym BUBLS (BUs Barn Location System), is applied to a case study with BC Transit, a large Canadian urban transit system. As the case study illustrates, BUBLS is currently employed in capital projects planning.

Vancouver regional health planning model

An aggregate simulation model of the health care system existing in Vancouver, Canada has been created as part of a multi-purpose regional simulation project. The model requires data on population trends, morbidity, health resource trends. Under a variety of possible policies (ZPG, for example) the effects in terms of surpluses and shortages of resources, untreated cases, and a scale of social impact attributable to Holmes are delineated over a n-year horizon. The results are intended to provide policy-makers with contingency forecasts for priority assignment, resource formation, and demand-resource matching.

Monte Carlo simulation on microcomputers

Monte Carlo analysis is a practical tech nique for including the effects of uncertainty in a model intended for decision support. It has been infrequently used, however, perhaps because it has been tedious and boring to do. A recently available software add-in to 1-2-3 named @Risk makes Monte Carlo analysis much easier. This paper demonstrates Monte Carlo analysis in spreadsheet simulation in 1-2-3 so that you are better able to judge whether or not you should employ it.

Emergency health care system models

Many models of emergency health care systems have been created, aided by the openness of the system to inspection, and the ready availability of data and research assistants. Simulation has been particularly popular due to the complex nature of models and I/0, the interest in the tails of response time distributions, and the probabilistic nature of performance criteria.In Vancouver, Canada, a number of simulation models have been created and results have been implemented. Current interest lies in multi-level ambulance models due to the relative scarcity of paramedic ambulances. Research in emergency health care systems is likely to continue

Risk management and consumer participation in medical decision making.

THE demand by consumers for a voice in decisions which affect their lives can be observed in many sectors of Western society. The health industry is one of these, as practitioners in public health can well testify. The concept of consumer sovereignty which is one of the basic premises of the free market system has seen little application in health care decision making. Differences between physicians and patients on the values associated with different courses of medical and preventive actions are to be expected. The physician views the world through a web of medical ethics, professional norms, and a subjective view of the patients life situation which the physician obtains in increasingly brief glimpses during his harried schedule of appointments. The consumer-patient views the world through his experiences and may give differing importance to such concerns as absence from his job, financial sacrifice, or absence from his family. The physician faced with a choice among alternative courses of medical action for a patient would benefit from greater knowledge of the attitudes of the patient toward the possible outcomes associated with each course of action and toward associated risks. Our purpose is to investigate choices involving risk in medical decision making and to identify factors and strategies which may improve the quality of direct and indirect consumer participation in medical decisions. In addition, we will explore possible research and development directed to such improvements. The questions of risk and consumer participation concern the public health sector in two ways: first, in preventive campaigns, such as mass immunization in schools, decisions are often made for the public without reference to its preferences among risk alternatives (should the public assume the risk associated with immunization or the deferred risk of contracting the disease?); second, the public health sector must assume major reBoth authors are with the University of British Columbia. Dr. Vertinsky is assistant professor of management science and ecology, and Dr. Uyeno is assistant professor of management science. Dr. Vertinsky is also assistant professor of epidemiology at the Tulane University School of Public Health and Tropical Medicine, New Orleans, La. Tearsheet requests to Dr. Ilan Vertinsky, University of British Columbia, Vancouver 8, B.C.

Forecasting the demand for maternity services.

Faced with demands on maternity services exceeding design capacity, one British Columbia hospital commissioned forecasting studies to determine trends in demand and if accurate forecasts could be obtained. In addition to describing the forecasting method employed, the data used and the results, the authors look at what literature is available on obstetrics forecasting.