UNIVERSITY EXAMINATIONS: 2011/2012
SECOND YEAR EXAMINATION FOR THE BACHELOR OF
SCIENCE IN INFORMATION TECHNOLOGY
BIT 2201 SIMULATION AND MODELLING
DATE: JULY, 2012 TIME: 2 HOURS
INSTRUCTIONS: Answer Question ONE and any other TWO
QUESTION ONE
a) Define the following terms:
i. Simulation (2 Marks)
ii. System (2 Marks)
iii. System State (2 Marks)
iv. System Image (2 Marks)
v. Simulation Algorithm (2 Marks)
b) Describe any two tests carried out on random numbers. (4 Marks)
c) Describe the three main characteristics that describe congestion in a system.
(6 Marks)
d) i. Use a congruential mixed random number generator with a = 11, c = 37,
m = 31, Xo = 23 to generate the first five random variates on the interval
(0,1) (5 Marks)
ii. Discuss the “build model right-build right model” philosophy of model
verification and validation. (5 Marks)
QUESTION TWO
a) Distinguish between verification and validation. (4 Marks)
b) Consider a single server queuing system. The system starts at time t=0. The
arrival times are 0.2, 0.3, 0.5, 0.7, 0.8, 1.0, 2.2, 2.9, 3.3, 3.6 4.0 and 4.5. The
departures are at times 1.4, 2.0, 3.2, 3.8, 4.2, 4.8 and 5.0. Simulate this system for
eight customers and hence estimate.
i. Average delay in queue. (5 Marks)
ii. Average number of clients in the queue. (9 Marks)
iii. Expected utilization of the server. (2 Marks)
QUESTION THREE
a) Define discrete event simulation. (2 Marks)
b) Describe the components found in most discrete event simulation models.
(10 Marks)
c) There’s logical organization for the components in (b) above that promotes the
programming, debugging and future changing of the simulation models computer
program. Using a well labeled flow chart, explain, the flow of control among
these components. (8 Marks)
QUESTION FOUR
a) For a queuing system where the service time t is exponentially distributed, such
that
Explain how you would estimate parameter λ . (8 Marks)
b) Most simulation programming systems include a report generator to print out
statistics gathered during the run. Describe any SIX common required statistics,
which are usually included in the output. (12 Marks)
QUESTION FIVE
a) Describe the three main characteristics that describe congestion in a system.
(6 Marks)
b) State five capabilities of a good simulation language. (5 Marks)
c) Among the most compelling reasons for using simulation are the benefits gained
by managers. Explain any THREE benefits. (9 Marks)
