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Simulation is used in nearly every engineering, scientific, and technological discipline. In the fifty years since its formal definition it has been adapted for a wide variety of applications. Today, the techniques are employed in the design of new systems, the analysis of existing systems, training for all types of activities, and as a form of interactive entertainment.
Design. Designers turn to simulation to allow them to characterize or visualize a system that does not yet exist and for which they wish to achieve the optimum solution. Manufacturing models may describe the capacities of individual machines, the time to prepare material for operation, time to transfer materials from one machine to another, the effects of human operators, and the capacities of waiting queues and storage bins. Simulations of new pieces of equipment may evaluate their performance, stress points, transportability, human interfaces, and potential hazards to the environment. Business process models may evaluate the flow of paperwork through a company to determine where redundancies or unnecessary operations are located, allowing them to redesign operations such that the same work can be performed with a fraction of the labor and time that has evolved into the process. Major airlines use simulations to study complex routing patterns for large numbers of aircraft traveling around the world. The intention is to identify routes that serve the most passengers and use the fewest assets most efficiently. Factors such as aircraft capacity, ground time, flight time, scheduled maintenance, crew availability, weather effects, and unscheduled downtimes are all considered in such models.
Simulation of a Manufacturing Production Line Courtesy of Imagine That Inc.
Analysis:
Analysis refers to the process of determining the behavior or capability of a system that is currently in operation. Unlike design, analysis may be supported by the collection of data from the actual system to establish model behaviors. The model can then be modified to determine the optimum configuration or implementation of the real system. A computer network can be described by the volume of traffic carried, the capacity of the lines and switches, performance of a router, and the path taken from sender to receiver. Based on measured message patterns, the network can be configured to deliver the most information using the shortest or most reliable paths available. In the health care industry, the models are used to schedule doctors, staff, equipment, and patients in an effort to improve service times and reduce costs. Social trends can be simulated to determine what services or goods will be needed at a given time by a specific sector of society. The impacts of aging, health, family composition, and a host of other factors can be predicted from an appropriate social model.
Traffic Flow Simulation Courtesy of Intergraph Computers Inc.
Training:
Training simulations recreate situations that people face on the job and stimulate the trainee to react to the situation until the correct responses are learned. These devices produce well prepared personnel without the expense of making mistakes on the job. Perhaps the best known of these are flight simulators, which model dangerous environments where life threatening situations can be mitigated through learning in a non-lethal environment. Military simulators replicate the performance characteristics of the aircraft, instruments in the cockpit, effects of weapons, support from other combat systems, communications with other pilots, and terrain over which the events occur. Similar systems are used to train the captains of large ocean-going ships to dock without destroying both a real ship and a real dock. Entire mock-ups are made of nuclear power control centers to teach operators how to respond to emergency situations and to identify potential hazards before a crisis occurs. Modern medical equipment is so expensive and scarce that simulations have been constructed to allow interns and nurses to practice, develop, and certify their skills without having to schedule training time on the real equipment, competing for its use by real patients.
Flight Simulator Courtesy of SEOS International Ltd.