Page 71 - DCAP601_SIMULATION_AND_MODELING

Unit 4: Discrete System Simulation (I)

4.3 Summary Notes

 In discrete-event simulation, the operation of a system is represented as a chronological
sequence of events. Each event occurs at an instant in time and marks a change of state in
the system.
 Although, discrete event simulation could conceivably be carried out by hand it can be
computationally intensive, therefore will invariably involve computers and software.
 Using on-screen animations in a simulation model enables the status of the model to be
viewed as it progresses e.g. a machine that breaks down may change its color to red. This
enables visual cues to be passed back to the operator of the simulation model, so action
could be taken.
 The main difference between traditional program development and Object
Oriented techniques is the way in which the data and the program code are stored and
manipulated.

 In a fixed time step model, a timer or clock is simulated by computer. This clock is
modernized by a fixed time interval (say, tau) and the system is observed to view if any
event has taken place during this unit time interval.
 In next-event simulation model the computer advances time to the incidence of the
subsequent event. So, shift is from event to event.

4.4 Keywords

Discrete-event Simulation: In discrete-event simulation, the operation of a system is represented
as a chronological sequence of events.

Entities: Representations of real-life elements e.g. in manufacturing these could be parts or
machines.
Fixed Time step Model: In a fixed time step model, a timer or clock is simulated by computer.

4.5 Self Assessment

Fill in the blanks:
1. In ...................... simulation, the operation of a system is represented as a chronological
sequence of events.

2. The simulation maintains at least one list of simulation events. This is sometimes called
the ......................
3. ...................... is responsible for controlling the time advance and executing discrete events.

4. With ...................... the prime motivation is not only portrayal of the running simulation
model but also the interaction with it.
5. Our Discrete-system Simulator (DSS) is used by ......................, the largest Greek telecom
company.
6. DSS provides an abstract model for the description of any ...................... network which is
independent of details of the underlying technology.
7. The full infection timeline in our malaria models corresponds to the “......................” in
Macdonald’s model.

LOVELY PROFESSIONAL UNIVERSITY 65