Simulation TechniquesPaulus TangkereIndustrial Model SimulationSession 4

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Simulation Imitation of reality. to understand the behavior of a system. to insure that we are doing the right thing.

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Simulation ModelingThe process of designing and creating a computerized model of a real or proposed system for the purpose of numerical experiment to develop better understanding of the behavior/dynamics of that system under a given set of conditions.Simulation is a powerful tool for design, modeling, analysis, and optimization of systems.

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Simulation ProcessMain ProgramInitialization RoutineTiming RoutineEvent RoutineLibrary RoutineReport GeneratorIs simulation over?

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Systems Modeling and Simulation Steps

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Elements of Simulation ModelEntities: items being processed by and flow through the system, e.g. parts, cars, customersAttributes: properties/characteristics assigned to entities, e.g. part types, time arrived in a queueVariables: changeable quantities defined to reflect the characteristics of the system, e.g. we may define two state variables for a M/M/1 system:Server status (states): idle or busyNumber of items waiting in queue

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Events: an event is an occurrence of something that changes the state of the system (e.g. arrival or departure of a customer in a M/M/1 system)Resources: means by which to process entities (e.g. machines, operators, fork-trucks)Queues (buffers, waiting lines): storage space for entities waiting for required resource)Activities/processes: an activity is a period of time during which an entity (entities) is serviced (e.g. processed or transferred). The duration of an activity is known a priori, and can be scheduled (e.g. processing time, transfer time)Elements of Simulation Model

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Statistical accumulators: variables that collect and keep track of statistics during the progress of simulation to obtain required output performance measures.Simulation clock: a mechanism to keep track of current (simulated) time in a simulation. It lurches from the time of one event to the time of next event.Elements of Simulation Model

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Case Service Station A customer who arrives and finds the server idle enters service immediately and the service times are random variables that are independent of the inter-arrival times. A customer who arrives and finds the server busy joins the end of a single queue. Upon completing service for a customer, the server chooses a customer from the queue (if any) in FIFO manner.The simulation will begin in the empty-and-idle state (no customers are present and the server is idle).

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Case Service Station

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Case Service Station

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Case Service Station

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Case Service Station

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Case Service Station

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Case Service Station