SIMULATION: Transactions of The Society for Modeling and Simulation International

Sullivan, Jim

doi: 10.1177/003754979205800603pmid: N/A

Ozel, Filiz

doi: 10.1177/003754979205800604pmid: N/A

A simulation model (BGRAF) capable of representing the emergency egress behavior of people in fires was developed at the University of Michigan. The software, written in Fortran, can be used to test different hypothesis about human behavior in fires. The cognitive effects of the physical environment were also incorporated into the decision making process simulated in this model. The graphic output animates the actions of the simulated people on a building plan on the screen. Tabular output is also provided. A building data base created by CAEADS computer-aided design software developed at the University of Michigan with partial funding from the U.S. Army Corps of Engineers is accessed by BGRAF during the input phase. The use of a CAD data base to model the physical environment was critical in creating an accurate model, since the actions of the simulated persons hinged upon the limitations of the physical environment.

doi: 10.1177/003754979205800605pmid: N/A

Saeed, Khalid

doi: 10.1177/003754979205800606pmid: N/A

This paper suggests that the possibility to experiment with relationships using system dynamics should lend the method easily to introducing experimental learning in economics and, possibly, also other social science disciplines. This would, however, require modifying teachingformats and creating new text materials and user- friendly computer programs incorporating the possibility to assemble hypothesized relationships by students with little computer or mathematical expertise. The paper reports work in progress towards the development of a simulation laboratory consisting of a text and a user friendly simulation program on issues of economic development as an example of the materials needed for integrating practicum with teaching.

Kleijnen, Jack P. C.

doi: 10.1177/003754979205800607pmid: N/A

In the December 1991 issue of this journal, Wild and Pignatiello proposed an experimental design strategy for designing robust systems using discrete-event simulation; their strategy used Taguchi's method for improving product and process quality in manufacturing. Now I propose two alternative techniques. One technique requires fewer observa tions than Taguchi's technique does. The second technique requires many more observations, but pays off since it quantifies the risk caused by uncontrollable environmental conditions.

Wild, Rosemary H.; Pignatiello, Joseph J.

doi: 10.1177/003754979205800608pmid: N/A

Gagliano, Ross A.; Fraser, Martin D.; Schaefer, Mark E.

doi: 10.1177/003754979205800609pmid: N/A

In this article, an alternative approach to control for computing systems, with possible distributed, parallel, or multilprocess application, is proposed and evaluated through simulation. Functions normally handled by centralized controllers, schedulers, arbiters and priority schemes are accomplished through a decentral ized model of control. Resource allocation, one important control function, is resolved within a Challenge Ring (CR) in which individual computing tasks independently (or without a host, hence their interaction is called hostless) exercise algorithms to gain access to computing resources.Simulated system performance is monitored by analyzing individual task processing times, total system times, resource availability, resource utilization, and system efficiency. Our preliminary experimental results indicate that such decentralized (or hostless) models can be superior to some standard centralized (or hosted) versions. Moreover, tasks in CR networks that interact through cooperative strategies in some cases exhibit better performance. Our overall results encourage the further exploration of decentralized control models which could be useful in the continuing pursuit of alternative machine constructs (e.g. non-von Neumann architectures) and new distributed operational schemes (e.g. hostless network operating systems).

Kleijnen, Jack P. C.; van Ham, Greet; Rotmans, Jan

doi: 10.1177/003754979205800610pmid: N/A

Sensitivity analysis is needed for valida tion, what-if analysis, and optimization of complicated simulation models. One set of techniques for sensitivity analysis consists of least squares curve fitting, regression analysis, and statistical designs such as factorial designs. In this case study these techniques are applied to several modules of a large integrated assessment model for the greenhouse effect, developed in The Nether lands. The regression models turn out to be valid approximations to the simulation models. Some estimated effects are quite surprising for the simulation users.