An Overview of Modeling and Simulation Processes in Decision Making

1. Chapt 3 Modeling & Simulation Processes • Intro/ steps in the process • Formulate problem • Specify the model • Build model • Simulate model • Use model • Support decision making • AweSim & Visual Slam

2. Formulate Problem Specify Model Build Model Simulate Model Use Model Support Decision Making Modeling & Simulation Processes • Use an iterative process where relationships & parameters are continually redefined & improved.

3. Formulate the Problem Focuses the modeling/ simulation efforts 1) Identify the Goal 2) Specify the system performance measures 3) Set objectives 4)Completely define the systems to be modeled

4. Formulate the Problem • Goals • specify what is to be achieved ie lower cycle time by capital investing • Performance measures • Measurable outputs ie profits/costs, inventory levels, speed, % waiting time • Objectives • More specific, ie reduce queue/bottle neck for process or provide redundant machine for maintenance/ redundancy • Complete definition • Scope and boundary definitions

5. Specify Model • Define system but w/o unnecessary detail • Easily understood but realistic • Reasonable simplifying assumptions • Include interactions of activities • Conceptualize data requirements • collected • use statistical methods

6. Build Model • Develop Simulation model • Interactive & Iterative- continually redefined, updated, modified & extended • Collect data • Time studies, accessing data bases, statistical • Define Experimental Controls • Number of sim runs, report types/ plots/ histograms, status of specific variables ie idle/busy • All steps are interdependent

7. Simulate Model • Run Model • Simulation advances time in accordance with the movement of entities thru nodes and activities • Verify Model • Does the model behave as expected ie correct CPM Does the model work right? • Validate the Model • Reasonable representation of the system, does the model truly represent reality? • Steps are interdependent/ have interactions

8. Use Model • Make the sim runs and interpretation of the data outputs • Make make several runs to find optimal solution • ie try run with one manufacturing set up - find output, tweak manufacturing set up - find out put, continue to tweak… • Evaluate alternatives…one bottle neck solved look for others that may crop up • Interactions….may need to rebuild model once see output

9. Support Decision Making • Presentation and documentation of the results/ outputs of the simulations • Graphical is best

10. AweSim Visual SLAM • Open architecture to databases, MS office, C/C++, Windows based • Project Structure builds scenarios to investigate alternate designs to improve a system • Build networks (models), perform simulations runs, view animations

11. AweSim Visual SLAM

12. AweSim Visual SLAM

13. Modeling & Simulation Process Exercises • # 3-2 Discuss the use of statistics and graphics in each of the steps of a modeling/ sim process • see fig 3-1 pg 36 • #3-4 Using the steps in the modeling/ sim process build an explanatory model of the university system to obtain an MSET • see fig 3-1 pg 36

14. Chapt 4 Application of Simulation • Intro/ steps in the process • Performance measures • Examples • Capital Expenditures in the steel industry • Risk analysis of Pipeline const • MOB using Extend

15. Application of SimulationIntroduction • Widely used by industrial engineering, management, by service industry, industrial products and government. • Manufacturing-plant layout, efficiencies, lean production • Project Controls-cost estimation, risk analysis, planning • Health care, transportation, communications, space flight, etc • Provided examples are only one solution… typically many and may take several iterations

16. Performance Measures • Performance of a systems is measured by the efficiency is achieving its objectives • Objectives vary dependent on type of system involved ie car production vs plant construction… general info provided by looking a manufacturing system

17. Performance Measuresfor Manufacturing Terms • System performance is combined with cost to establish profitability….Sim focuses on performance • Throughput= production rate output/time • Capacity=max throughput • Flow time= amount of time a job spends in the system…want to min this • Resources=people, mtls,equip, machines, etc want to max their utilization=time productive

18. Performance Measuresfor Manufacturing Terms • WIP= Work In Progress…unfinished units awaiting parts, mtl etc = want to min this

19. Dumping Area Basic Oxygen furnace Shop Proposed Desulfurization Area Proposed Scrap Melter Blast Furnace Area C F g H J Capital Expenditure in the Steel Industry • Improve ops involving melting scarp & desulfuring metal by determining # of submarines that cost $1M

20. Dumping Area Basic Oxygen furnace Shop Proposed Desulfurization Area Proposed Scrap Melter Blast Furnace Area C F g H J Capital Expenditure in the Steel Industry • Model scheduling rules, add rule to dump hot metal if submarine is not available to accommodate blast furnace..sim save buying another sub

21. Prep trench Lay Pipe Weld pipe Cover & finish Risk Analysis of Pipeline const • Problem formulation= complete project by specific due dates • Sim construction activities based on weather and inputs to resources (people, equip, etc)

22. Use of Models • Modeling & Sim used to enhance system performance or solve problems, Also for: • Explanatory to understand a problem • Communication to describe • Training • Analysis • Review design alts

23. Application of SimulationExercises • Using a block wiring diagram, develop a model for repairing/replace a building foundation • Want most efficient use of recourses • Activities are: • lift up on jacks/ supports • remove existing foundation • Form/ pour new concrete foundation • Remove form/ lower building • Write what variables to Sim to create most efficient system

24. Application of SimulationMOB