MIS470 2

Chapter 10: Modeling and Analysis: Heuristic Search Methods and Simulation

Learning Objectives • Explain the basic concepts of simulation and when to

use it

• Understand the concepts and applications of different types of simulation

• Explain what is meant by Monte Carlo and discrete event simulation

Simulation • Simulation is the “appearance” of reality

• It is often used to conduct what-if analysis on the model of the actual system

• It is a popular DSS technique for conducting experiments with a computer on a comprehensive model of the system to assess its dynamic behavior

• Often used when the system is too complex for other DSS techniques

Application Case 10.3

Simulating Effects of Hepatitis B Interventions

Questions for Discussion 1. Explain the advantage of operations research methods such

as simulation over clinical trial methods in determining the best control measure for Hepatitis B.

2. In what ways do the decision and Markov models provide cost-effective ways of combating the disease?

3. Discuss how multidisciplinary background is an asset in finding a solution for the problem described in the case.

4. Besides healthcare, in what other domain could such a modeling approach help reduce cost?

Major Characteristics of Simulation • Imitates reality and captures its richness both in

shape and behavior • “Represent” versus “Imitate”

• Technique for conducting experiments

• Descriptive, not normative tool

• Often to “solve” [i.e., analyze] very complex systems/problems

• Simulation should be used only when a numerical optimization is not possible

Advantages of Simulation

• The theory is fairly straightforward

• Great deal of time compression

• Experiment with different alternatives

• The model reflects manager’s perspective

• Can handle wide variety of problem types

• Can include the real complexities of problems

• Produces important performance measures

• Often it is the only DSS modeling tool for non-structured problems

Disadvantages of Simulation

• Cannot guarantee an optimal solution

• Slow and costly construction process

• Cannot transfer solutions and inferences to solve other problems (problem specific)

• So easy to explain/sell to managers, may lead to overlooking analytical solutions

• Software may require special skills

Simulation Methodology Steps: 1. Define problem 5. Conduct experiments

2. Construct the model 6. Evaluate results

3. Test and validate model 7. Implement solution

4. Design experiments

Simulation Types

• Probabilistic/Stochastic vs. Deterministic Simulation • Uses probability distributions

• Time-dependent vs. Time-independent Simulation • Monte Carlo technique (X = A + B)[A, B, and X are all

distributions]

• Discrete Event vs. Continuous Simulation

• Simulation Implementation • Visual Simulation and/or Object-Oriented Simulation

Visual Interactive Simulation (VIS)

• Visual interactive modeling (VIM), also called Visual Interactive Simulation or Visual interactive problem solving

• Uses computer graphics to present the impact of different management decisions

• Often integrated with 3G and GIS

• Users can perform sensitivity analysis

• Static or dynamic (animation) systems

• Virtual reality, immersive, …

Traffic at an Intersection from the Orca Visual Simulation

Application Case 10.4

Improving Job-Shop Scheduling Decisions Through RFID: A Simulation-Based Assessment

• Background • Problem description • Proposed solution • Results

SIMIO Simulation Software

SIMIO Simulation Software

SIMIO Simulation Software

Simulation Software

• A comprehensive list can be found at • orms-today.org/surveys/Simulation/Simulation.html

• Simio LLC, simio.com

• SAS Simulation, sas.com

• Lumina Decision Systems, lumina.com

• Oracle Crystal Ball, oracle.com

• Palisade Corp., palisade.com

• Rockwell Intl., arenasimulation.com …