WSC 2004 Final Abstracts

Wednesday 8:30:00 AM 10:00:00 AM
General Applications of Simulation I
Chair: Feng Yang (Northwestern University)

Web Based Evaluation of Material Handling Alternatives for Automated Manufacturing: A Parallel Replications Approach
William E. Biles and John Brian Casebier (University of Louisville)

Abstract:
This paper describes the application of a master/slave configuration of processors to study a comparison of alternative material handling configurations for automated manufacturing. Such a study usually requires a large number of simulation replications, and carrying out those replications on a multi-processor platform yields significant savings in elapsed time. In the present application, a master processor carries out the statistical computations for a 2k factorial design on up to eight slave processors. This paper will compare the results from using two, four and eight processors.

Validation and Calibration of Human Performance Models to Support Simulation-Based Acquisition
Floyd Glenn, Kelly Neville, James Stokes, and Joan Ryder (CHI Systems, Inc.)

Abstract:
We present a methodology under development for calibration and validation of human performance models in support of simulation-based acquisition processes — a human performance modeling validation program. We describe a conceptual framework based on an investigation of the characteristics of a wide variety of performance modeling frameworks and application domains. We offer initial taxonomies of model actions and empirical performance actions that will support the necessary mappings between model predictions and empirical observations for all models over the full range of required representation detail, and across all stages of the acquisition process in order to establish a solid analytic basis for calibration and validation of SBA processes and human performance modeling frameworks. We describe methods for specifying performance measures so that for any given design decision, performance measures captured using a model can be mapped to performance measures obtained during live test and evaluation.

Dynamic Radiation Dose Visualization in Discrete-Event Nuclear Facility Simulation Models
George Tompkins, Drew E. Kornreich, Robert Y. Parker, Andrew C. Koehler, Johnell M. Gonzales-Lujan, and Robert J. Burnside (Los Alamos National Laboratory)

Abstract:
To improve its process modeling capabilities, Los Alamos has worked toward integrating dose modeling tools with advanced discrete-event simulation tools. To date, dose information for a model was preprocessed and then incor-porated into a process model. In this paper, we describe a quantum improvement in our capabilities by linking a dose calculation kernel to the discrete-event modeling environ-ment through the customizable routine capabilities pro-vided by the Flexsim™ code. The Flexsim™ model uses ray-tracing routines to calculate the source and detector lo-cations and determines the materials, thickness, and order of any shields between the source and detector. With this information, the dose calculation kernel is then able to cal-culate, in a post-processing setting, the associated dose. Thus, we are able to determine the time-varying and inte-grated exposure of workers to ionizing radiation, which will be integral to planning for future nuclear facilities in the DOE complex.

Abstract:
In order to support the conceptualization and specification of simulation models of complex systems, several formalisms or world views exist. Petri nets, differential equations, discrete event system specification and process interaction are typical examples. Throughout the last decade many have attempted to implement theprocess interaction formalism in Java. These initiatives mostly resulted in multi-threaded simulation languages in which a Process extends a Thread. These threads are then sequentially suspended and resumed. The article "Why are Thread.stop, Thread.suspend and Thread.resume Deprecated?" (Sun Microsystems, 1999) implicitly ended most of these deadlock prone initiatives. This paper introduces a unique single-threaded implementation of this world view by introducing a Java-based Java interpreter, which is used only to interpret pausable processes. This interpreter supports all Java programming constructs and hopefully serves as a cornerstone for renewed development of process oriented Java based simulation languages.

Integration of the FreeBSD TCP/IP-Stack into the Discrete Event Simulator OMNet++
Roland Bless and Mark Doll (University of Karlsruhe)

Abstract:
The discrete event simulator OMNeT++, that is programmed in C++, shows a steady growing popularity. Due to its well-structured nature, it is easy to understand and easy to use. A shortcoming of it, however, is the limited number of available simulation models. Especially, for network simulations a validated TCP implementation was missing. In order to avoid a re-implementation of a full-featured TCP, including all potential implementation errors and costly validation tests, we integrated a TCP/IP stack of a real operating system into OMNeT++. In this paper we show that such a port is feasible with reasonable effort and we describe difficulties of the integration process as well as the applied solutions. We also present some evaluation results that outline memory and CPU usage.

Single-Threaded Specification of Process-Interaction Formalism in Java
Peter H.M. Jacobs and Alexander Verbraeck (Delft University of Technology)