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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 2 Examinations 2008/
Module Title: Computer Simulation and Modelling
Module Code: COMP 9005
School: Computing & Mathematics
Programme Title: Master of Science in Software Development
Programme Code: KSDEV_9_Y
External Examiner(s): Dr J F Power Internal Examiner(s): Dr J Creagh
Instructions: Answer THREE questions. Note 120 marks maximum.
Duration: 2 Hours
Sitting: Summer 2009
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination paper. If in doubt please contact an Invigilator.
- (a) (i) What are the main properties that a “good” arithmetic random-number generator should posess? (5 marks) (ii) Explain LCG generators. Use m = 7, a = 5, c = 3 and Z (^) o = 6 to generate a sample sequence. (8 marks) (iii) For LCG generators with a very long period, explain the concept of generating different streams. Why are different streams necessary for computer simulation modelling? (7 marks) (iv) Briefly, outline the Fabonacci generator and the expanded version of the Fabonacci generator. What is the main property of the expanded version of the Fabonacci generator that is of benefit to simulation modelling? (7 marks)
(b) (i) Define ‘generating random variates’. (2 marks) (ii) Write an algorithm and give the C/C++ code structure for the generation of exponential continuous random variates. An explanation is required. (11 marks)
- (a) (i) From a modelling viewpoint, explain the usefulness of each of the following distributions:
- Triangular
- Erlang
- Normal (8 marks) (ii) How may you estimate the values of the parameters of the following distributions:
- Normal
- Lognormal
- Beta
- Exponential (6 marks)
- (a) (i) The simulation process proposed by Pegden, Shannon and Sadowski recommend 12 stages. Give a diagram. Also, give a very brief description of each phase. (8 marks) (ii) Give a detailed description of the first 3 stages of the simulation process. Why are these 3 stages so vital to the successful generation of a simulation model? (8 marks)
(b) Multiple random number streams are recommended to reduce variance in a simulation. Explain why this is true? (7 marks)
(c) Consider the classical ‘time shared system’ problem. N terminals exist. The users at a terminal wait and later submit work or a job to a round robin scheduler for a single processor system. Choose your own arrival times and server times. Develop a solution for:
- a flowcharting model
- an event graph model
- a SPN model Compare your solutions. (17 marks)
- (a) (i) Define
- Analytic Simulation
- Simulation Virtual Environments and list characteristics of each. (8 marks) (ii) DIS simulations usually encorporate deadreckoning.
- Give a clear example of deadreckoning.
- What are the advantages of deadreckoning?
- What are the disadvantages of deadreckoning? (8 marks)
(b) Cleary describe the major components of Run-Time Infrastructure (RTI) implementation architecture. An architecture diagram for the following example must clearly illustrate the major components.
EXAMPLE: 3 federations are defined. The BUS federation contains two federates Bus Engine and Passenger. The TRUCK federation contains three federates Truck Engine, Load and Driving Conditions. The CAR federation contains two federates Car Engine and Environment. (14 marks)
(c) With reference to the HLA country population federation case study, describe how to write a program for a time stepped federate. C++ code elements are required. (10 marks)
