Chap018s-Simulation.ppt

7/28/2019 Chap018s-Simulation.ppt

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18s-1 Simulation

William J. Stevenson

Operations Management

8th edition


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18s-2 Simulation

CHAPTER

18s

Simulation

McGraw-Hill/Irwin

Operations Management, Eighth Edition, by William J. StevensonCopyright 2005 by The McGraw-Hill Companies, Inc. All rights reserved.


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18s-3 Simulation

SimulationSimulation: a descriptive technique that enablesa decision maker to evaluate the behavior of a

model under various conditions.

Simulation models complex situations

Models are simple to use and understand

Models can play what if experiments

Extensive software packages available


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18s-4 Simulation

Simulation Process1. Identify the problem

2. Develop the simulation model

3. Test the model

4. Develop the experiments

5. Run the simulation and evaluate results

6. Repeat 4 and 5 until results are satisfactory


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18s-5 Simulation

Monte Carlo SimulationMonte Carlo method: Probabilistic simulation

technique used when a process has a randomcomponent

Identify a probability

distribution

Setup intervals ofrandom numbers tomatch probability distribution

Obtain the random numbers

Interpret the results


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18s-6 Simulation

Example S-1


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18s-7 Simulation

Example S-1


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18s-8 Simulation

Simulating Distributions Poisson

Mean of distribution is required

Normal

Need to know the mean and standarddeviation

Simulatedvalue Mean Randomnumber Standarddeviation+ X=


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18s-9 Simulation

Uniform Distribution

a b0 x

F(x)

Simulated

valuea + (b - a)(Random number as a percentage)=

Figure 18S.1


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18s-10 Simulation

Negative Exponential DistributionFigure 18S.2

F(t)

0 T t

P t T RN( ) .

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18s-11 Simulation

Computer Simulation

Simulation languages SIMSCRIPT II.5

GPSS/H

GPSS/PC

RESQ

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18s-12 Simulation

Advantages of Simulation

Solves problems that are difficult or impossible tosolve mathematically

Allows experimentation without risk to actualsystem

Compresses time toshow long-term effects

Serves as training tool

for decision makers

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18s-13 Simulation

Limitations of Simulation Does not produce optimum solution

Model development may be difficult

Computer run time may be substantial

Monte Carlo simulation only applicable to

random systems

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18s-14 Simulation

Additional PowerPoint slides

contributed byGeoff Willis,

University of Central Oklahoma.

CHAPTER

18s

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18s-15 Simulation

Why Simulate?

Math too complicated Easier to manipulate than reality

Software and hardware permit modeling

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18s-16 Simulation

Simulation Steps

Problem formulation Model building

Data acquisition

Model translation

Verification & validation

Experiment planning & execution

Analysis

Implementation & documentation

Chap018s-Simulation.ppt

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