Simulation N Modeling

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  • Topic: Queueing theory, Time, Computer simulation
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System Modeling And Simulation Notes ­—­—­—­—­—­—­ ­ Presented By

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CHAPTER – 1

INTRODUCTION TO SIMULATION

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Simulation A Simulation is the imitation of the operation of a real-world process or system over time. Brief Explanation • The behavior of a system as it evolves over time is studied by developing a simulation model. • This model takes the form of a set of assumptions concerning the operation of the system. The assumptions are expressed in o Mathematical relationships o Logical relationships o Symbolic relationships Between the entities of the system. Measures of performance The model solved by mathematical methods such as differential calculus, probability theory, algebraic methods has the solution usually consists of one or more numerical parameters which are called measures of performance. 1.1 When Simulation is the Appropriate Tool • Simulation enables the study of and experimentation with the internal interactions of a complex system, or of a subsystem within a complex system. • Informational, organizational and environmental changes can be simulated and the effect of those alternations on the model’s behavior can be observer. • The knowledge gained in designing a simulation model can be of great value toward suggesting improvement in the system under investigation.

• Simulation can be used as a pedagogical device to reinforce analytic solution methodologies.

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• By changing simulation inputs and observing the resulting outputs, valuable insight may be obtained into which variables are most important and how variables interact.

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• Simulation can be used to experiment with new designs or policies prior to implementation, so as to prepare for what may happen. • Simulation can be used to verify analytic solutions. • By simulating different capabilities for a machine, requirements can be determined. • Simulation models designed for training, allow learning without the cost and disruption of on-the-job learning. • Animation shows a system in simulated operation so that the plan can be visualized. • The modern system(factory, water fabrication plant, service organization, etc) is so complex that the interactions can be treated only through simulation.

1.2 When Simulation is Not Appropriate • Simulation should be used when the problem cannot be solved using common sense. • Simulation should not be used if the problem can be solved analytically. • Simulation should not be used, if it is easier to perform direct experiments. • Simulation should not be used, if the costs exceeds savings. • Simulation should not be performed, if the resources or time are not available. • If no data is available, not even estimate simulation is not advised.

• If there is not enough time or the person are not available, simulation is not appropriate.

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• If managers have unreasonable expectation say, too much soon – or the power of simulation is over estimated, simulation may not be appropriate. • If system behavior is too complex or cannot be defined, simulation is not appropriate.

1.3 Advantages of Simulation • Simulation can also be used to study systems in the design stage. • Simulation models are run rather than solver. • New policies, operating procedures, decision rules, information flow, etc can be explored without disrupting the ongoing operations of the real system. • New hardware designs, physical layouts, transportation systems can be tested without committing resources for their acquisition. • Hypotheses about how or why certain phenomena occur can be tested for feasibility. • Time can be compressed or expanded allowing for a speedup or slowdown of the phenomena under investigation. • Insight can be obtained about the interaction of variables. • Insight can be obtained about the...
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