Chapter 1 What Is Simulation Introduction The objective

Chapter 1 What Is Simulation Introduction The objective of simulation – Analysis the system (Model) Analytically the model – a description of some system intended to predict the behavior inside Analysed by simulation Driving certain model with input And obtain the proper output

Modeling What’s being modeled? Computer simulation deals with models of systems. System – a facility or process, either actual or planned; a collection of entities (such as: worker, machine, service) act and interact together to obtain certain logical end (product). The primary goal is to focus attention on understanding how the system currently worked.

Modeling How about just playing with the system?

Modeling Sometimes you cannot play with the system!

Modeling Models Physical Models (Iconic Models) Logical Models (Mathematical Models) A full-scale of a fast-food restaurant Usually represented in a Computer program queueing theory differential equation linear prpgramming simulation

Computer Simulation Thomas and Da. Costa (1979) Survey 137 large firms -Statistical 94% -Simulation 84%

Computer Simulation The Classification of Simulation Model Static vs. Dynamic – Time does’t play a natural rule in static models but does in dynamic models. Continuous vs. Discrete – In a continuous model, the state of the system can change continuously over time. In a discrete model, change can occur only at seperated points in time.

Computer Simulation The Classification of Simulation Model Deterministic vs. Stochastic – Models that have no random input are deterministic. Stochastic models operate with random input.

Computer Simulation Note: State – variable to describe a system at certain time (such as: a single server queue; bankteller, customer, machine, computer jobs ) Ex: Customer arrives randomly and the policy of service is FIFO (first in first out), the times between successive arrivals are A 1, A 2, A 3 , …. The service times are B 1, B 2, B 3, …. Assuming at time 0, system is empty. The state can be (1) # queue at certain time (2) # customer leaving the system (3) state of server (busy or idle)