© Yilmaz “Introduction to Discrete-Event Simulation” 1 Introduction to Discrete-Event Simulation Dr. Levent Yilmaz M&SNet: Auburn M&S Laboratory Computer Science & Software Engineering Auburn University, Auburn, AL COMP8700 Agent-Directed Simulation

© Yilmaz “Introduction to Discrete-Event Simulation” 2 Use of Simulation for AgentsUse of Agents for Simulation Agent Simulation: simulation of agent systems. Agent simulation is already used in several categories of application areas such as: - Engineering applications: electrical engineering, irrigation systems, manufacturing systems, mechatronics, networks, robotics, software, as well as transportation/logistics; - Management/economy applications: economy, e- commerce, and management; - Social systems and human behaviour applications: social systems, psychology/human behaviour, physiology, negotiation, and organization theory; - Environment applications: ecosystems, land use; - Military applications. Agent-supported Simulation: use of agents in a simulation study for at least one of the following purposes: (in a computer-aided simulation environment –including simulation-based problem solving environments): - to provide computer assistance for front-end and/or back-end interface functions; - to process elements of a simulation study symbolically (for example, for consistency checks and built-in reliability); and - to provide cognitive abilities to the elements of a simulation study, such as learning or understanding abilities. Agent-based Simulation: use of agents for the generation of model behavior in a simulation study Agent-Directed Simulation

© Yilmaz “Introduction to Discrete-Event Simulation” 3 Aim The aim of this lecture is to overview the fundamentals, underlying principles, conceptual frameworks, and the life-cycle of a discrete-event simulation study.

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© Yilmaz “Introduction to Discrete-Event Simulation” 28 The initialization include the assignment of initial values to all the attributes. Fixed time increment is as the time flow mechanism. If an activity’s condition is satisfied, the actions of that activity are executed.

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© Yilmaz “Introduction to Discrete-Event Simulation” 30 The three phase approach combines activity scanning and event scheduling frameworks. Unlike the two-phased approach the time flow mechanism implements a variable time increment approach. All B (bound to occur – unconditional) activities with occurrence times equal to the simulation clock are executed before activity scanning takes place.

© Yilmaz “Introduction to Discrete-Event Simulation” 31 Under this framework the life cycle of an object that moves through and interacts with the processes of the system is represented. Initialization phase creates the attributes and dynamic objects. In the clock update phase the time is advanced to the move time of the front-end object of the FOL. All objects with equivalent move time are transferred to COL, which is processed in the scan phase.

© Yilmaz “Introduction to Discrete-Event Simulation” 32 Problem formulation is the process by which the initially communicated problem is translated into a formulated problem sufficiently well defined to enable specific research action. Not enough attention is given in the life cycle. The accuracy of problem formulation greatly affects the acceptability and credibility of simulation results.

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