Simulation Software Survey: To Boldly Go …
Discrete-event simulation software tools explore strange new worlds and re-examine one we thought we already knew.
By James J. Swain
Even the fabled Enterprise cannot surpass the bold new worlds that simulation software can go, beyond what anyone can witness and only limited by what can be imagined. For over 50 years, simulation has truly been used to explore strange new worlds and re-examine the ones that we knew, to make predictions, for insight, or simply for pure entertainment.
The sky is never the limit for simulation, and it has been used to chart the future course of shuttles and satellites, and to ensure that airplanes land safely. For instance, at Marshall Space Flight Center, NASA engineers work to perfect the Ares rockets and plot the path back to the moon and beyond to the planet Mars.
Here on Earth, last spring banks across the country were subjected to a Treasury Department inspired “stress test” to ensure that the U. S. financial system itself did not come crashing down. The test was administered through simulation, subjecting each bank and its portfolio of assets to a range of conditions in the economy, such as unemployment rates and mortgage defaults, to determine whether each institution had sufficient reserves to remain viable over the near horizon. As with a heart patient, the hope was to uncover the risk of a problem prior to an actual emergency, and to begin the necessary treatment.
As with any simulation effort, much discussion has been given about the assumptions employed in the stress tests. Are the tests realistic and sufficiently stressful to provide useful insights? Billions of dollars and the health of the financial sector are at risk, so the importance cannot be minimized.
While the economy and the health of the financial sector have been on everyone’s mind for the last year, not all applications of simulation have such far-reaching consequences. The start of the football season means not only the opportunity to replace speculation and anticipation with results, but the results can be used to drive the fortunes of simulated fantasy teams across the country. An estimated 27 million fans take part in fantasy league teams, finding entertainment and perhaps vindication in tens of millions of simulated matchups, driven by the statistics of the actual game results. The results of the real season will live on in a vast array of simulated games.
Entertainment based on simulation has been growing for over a decade. Simpleminded “shooter” games have given way to realistic and lavishly animated games. One can race a car, pilot an aircraft (or spacecraft) or compete in a variety of sports. You can become a fighter ace from several historic conflicts, using equipment seen only in air shows, or imagine what the fight will be in some future conflict. Multi-user games provide the ability to connect players in close combat or fantasy adventure. The genre is so popular that the U.S. Army exploits it with the America’s Army game as a recruiting and training tool.
Of course, if playing in the NFL or changing the course of WWII in Europe are not sufficiently arresting, the game Spore allows you to design life from micro organism up, and guide evolution to a new direction and colonize the stars. If that is too far reaching, you can build a simulated ant colony or recreate social living through SimAnt and the Sims.
All of these applications only begin to suggest the range and flexibility of simulation as a tool. This versatility is among the characteristic reasons for its success. Because simulation is constructive — we emulate the process that we seek to explore through rules obtained by observation and experience — formulation is fundamentally a descriptive process. The computer is an ideal platform for implementing such a tool, and the software infrastructure to support simulation has grown continuously over the last half-century.
As I have noted in earlier surveys, the migration of simulation into the public arena over the last decade may prove to be the most significant recent change in the field. For most of the history of simulation, specialized professional applications have driven the development of simulation. Even with the government as a major user of simulation, this has limited the applications of simulation. By contrast, commercial simulation products in entertainment have created lucrative markets that have spurred an increasingly rapid pace of innovations.
These innovations should make it possible to increase the role that simulation plays in the classroom. Up to this point training simulators have been rather specialized and expensive, largely the domain of large commercial enterprises. As it becomes easier to build realistic “virtual reality” simulations, these can be used in the classroom to make more realistic (and compelling) case studies, and provide some of the background that only industrial experience could provide before.
OR/MS Today, the magazine of membership of the Institute for Operations Research and the Management Sciences (INFORMS; www.informs.org), recently conducted its eighth biennial survey of simulation software for discrete-event systems simulation and related products (see Swain, 2007, for the previous survey). Vendors provided all product information. Products that run on personal computers to perform discrete-event simulation have been emphasized, since these are the most suitable for usage in management science and operations research. Simulation products whose primary capability is continuous simulation (systems of differential equations observed in physical systems) or training (e.g., aircraft and simulators) are omitted here.
The survey that appeared in OR/MS Today included 48 products taken from 25 vendors. The range and variety of these products continues to grow, reflecting the robustness of the products and the increasing sophistication of the users. The information elicited in the survey from the vendors is intended to provide a general gauge of the product’s capability, special features and usage. The survey includes information about experimental run control (e.g., batch run or experimental design capabilities) and special viewing features, including the ability to produce animations or demonstration that can run independent of the simulation software itself. A separate listing gives contact information for all of the vendors whose products are in the survey. The survey is available at (www.lionhrtpub.com/orms/surveys/Simulation/Simulation.html) and will include vendors who missed the publishing deadline. Of course, most of the vendors provide their own Web sites with further details about their products. Many of the vendors also have active users groups that share experience in the specialized use of the software and are provided with special access to training and program updates.
There are a number of technical and professional organizations and conferences devoted to the application and methodology of simulation. The INFORMS publications Management Science, Operations Research and Interfaces publish articles on simulation. The INFORMS Simulation Society sponsors simulation sessions at the national INFORMS meeting and makes awards for both the best simulation publication and recognition of service in the area, including the Lifetime Achievement Award for service to the area of simulation. Further information about the Simulation Society can be obtained from the Web site www.informs-cs.org. This site now provides the complete contents of the Proceedings of the Winter Simulation Conference from 1997 to 2008, and also contains links to many vendors of simulation products and sources of information about simulation, simulation education and references about simulation. The Society for Modeling and Simulation International (www.scs.org) is also devoted to all aspects of simulation. Their conferences include the Huntsville Simulation Conference that takes place annually in Huntsville, Ala.
The INFORMS Simulation Society and the Society for Modeling and Simulation are both sponsors of the annual Winter Simulation Conference. This year’s conference will be held Dec. 13-16 at the Hilton Austin Hotel in Austin, Texas. This year the conference will be held together with the Modeling and Analysis of Semiconductor Manufacturing (MASM) conference. Further information and registration information is available from the site www.wintersim.org.
The range of simulation applications can be surveyed through published sources such as the Proceedings of the Winter Simulation Conference and many of the vendor Web sites. The latter serve to illustrate the range of the products and to provide illustrations about the application of the software, typical means of analysis and success gained from simulation.
Transportation systems and supply chains have been increasingly important objects of simulation. The coordination of different modes of transportation, often over great distances between supply and customer, requires considerable study and tuning. Shipping ports are increasingly busy, increasingly automated and require coordination between different modes of transportation. For instance, containers from large container ships are unloaded, transferred to rail or truck for distribution, or may be loaded onto other ships for coastal or river based distribution. Airports likewise process varied traffic of their own, including arriving and departing passengers, aircraft, and involve the rapid distribution of baggage between aircraft.
Simulation is increasingly being used both for traditional security analyses to defend against terrorist threats of various types. In addition, simulation is a vital adjunct to planning responses to weather threats such as hurricanes, tidal surges, and most recently the spread of infectious diseases. The focus of analysis may be to assess vulnerabilities, assess counter measures, and to determine methods of evacuation in the face of various threats.
While simulation is used for large problems such as transportation and security, it is also useful for smaller-scale investigations. In the area of human factors, for instance, simulation plays an important role in assessing the design of control stations, including the mode, location and frequency of information being presented. Simulation is also used to plan maintenance access and often serves as the basis for maintenance procedures. In extreme cases, such as EVA operations on the space station, virtual simulations are used to test how a mission will be accomplished and then train personnel. Virtual astronauts can be used to perform initial design to estimate the feasibility of an approach and ergonomic characteristics such as limitations to range of motion, difficulty and fatigue.
James J. Swain (firstname.lastname@example.org) is professor and chair of the ISEEM department at the University of Alabama in Huntsville.
1. J. J. Swain, 2007, “Discrete Event Simulation Software: New Frontiers in Simulation,” OR/MS Today, Vol. 34, No. 5, October 2007, pp.32-43.
For an updated list of simulation software vendors who participated in the survey, the performance capabilities of their respective products, new features, comments and other information, visit: