SAE 599 - Modeling and Simulation for Systems Architecting and Engineering

1. SAE 599 - Modeling and Simulation for Systems Architecting and Engineering Dr. Raymond Madachy September 26, 2007

2. Outline Course Project Status Continuous Systems Modeling with Demonstrations Extend Demonstration

3. Course Project Status Projects Tony DiCarlo - xx Jared Fortune � EZSIM II architecting and acceptance testing (EZSIM) Pernell Gray - Airport system delays Ben Haas - Laser clearinghouse Harry Johnson � Sustaining engineering for the International Space Station integration processes (Simulink) Lloyd Matthews � xx Mauricio Pe�a - Fotochatter social network Jared Smith - Resource adaptability model for disasters and terrorist attacks David Voracek - NASA Dryden hiring and training process Initial status presentations extended to October 10

4. Continuous Systems Examples Hiring delay Learning curves Exhaustion Rayleigh effort curve ODC COQUALMO defect dynamics Earned value Integrated project model Inspection model Some are discrete systems modeled as continuous

5. Delays Time delays are ubiquitous in processes They are important structural components of feedback systems. Example: hiring delays in software development. the average hiring delay represents the time that a personnel requisition remains open before a new hire comes on board

6. Learning Curve

7. Learning Curve Models

8. Exhaustion Model Assumptions Workers increase their effective hours by decreasing slack time or working overtime The maximum shortage that can be handled varies. Workers are less willing to work hard if deadline pressures persist for a long time. The overwork duration threshold increases or decreases as people become more or less exhausted. The exhaustion level also increases with overwork. The multiplier for exhaustion level is 1 when people work full 8 hour days, and goes over 1 with overtime. The exhaustion increases at a greater rate in overtime mode up to the maximum tolerable exhaustion. The exhaustion level slowly decreases when the threshold is reached or deadline pressures stop with an exhaustion depletion delay. During this time, workers don�t go into overwork mode again until the exhaustion level is fully depleted.

9. Exhaustion Model

10. Exhaustion Model Relationships

11. Exhaustion Behavior

12. Rayleigh Manpower Distribution Rayleigh curve is a popular model of personnel loading Assumptions: Only a small number of people are needed at the beginning of a project to carry out planning and specification. As the project progresses and more detailed work is required, the number of staff builds up to a peak. After implementation and unit testing is complete, the number of staff required starts to fall until the product is delivered. The number of people working on a project is approximately proportional to the number of problems ready for solution at that time

13. Rayleigh Formula A Rayleigh curve describes the rate of change of manpower effort per the following first order differential equation: where C(t) is the cumulative effort at time t, K is the total effort, and p(t) is a learning function. The learning function is linear and can be represented by where a is a positive number. The manpower rate of change represents the number of people involved in development at any time (staffing profile). The a parameter is an important determinant of the peak personnel loading called the manpower buildup parameter.

14. Rayleigh Curve Applicability Rayleigh curve was based on initial studies of hardware research and development projects resemble traditional waterfall development for unprecedented systems Rayleigh staffing assumptions don�t hold well for COTS, reuse, architecture-first design patterns, 4th generation languages or staff-constrained situations However an �ideal� staffing curve is proportional to the number of problems ready for solution (from a product perspective).

15. Rayleigh Model

16. Interactive Rayleigh Model Demo

17. Dynamic ODC COQUALMO Portion Portion for Requirements Completeness defects only:

18. Dynamic ODC COQUALMO Sample Outputs Example of applying increased V&V for Execution Testing and Tools at 18 months:

19. Earned Value Earned value is a method for measuring project performance. It compares the amount of work that was planned with what was actually accomplished to determine if cost and schedule performance is as planned. Cost performance index (CPI) is the ratio of budgeted costs to actual costs (BCWP/ACWP) Schedule performance index (SPI) is the ratio of work performed to work scheduled (BCWP/BCWS)

20. Guidelines for Using Earned Value If effort is more than 15% complete and your baseline estimates are being overrun, you cannot recover. The overrun at completion will be greater than current overrun (based on over 700 DoD contracts). far term estimates are probably worse than short-term estimates Adjust far-term estimates and figure out how to not get worse.

21. Earned Value Example Project #2 (hard problems first) finishes sooner

22. Earned Value Model

23. Introduction to Inspection Model Research problem addressed What are the dynamic effects to the process of performing inspections? Model used to evaluate process quantitatively demonstrates effects of inspection practices on cost, schedule and quality throughout lifecycle can experiment with changed processes before committing project resources benchmark process improvement support project planning and management Model parameters calibrated to Litton and JPL data error generation rates, inspection effort, efficiency, productivity, others Model validated against industrial data

24. System Diagram

26. Effects of Inspections

27. Inspection Policy Tradeoff Analysis Varying error generation rates shows diminishing returns from inspections [Madachy 94]:

28. Derivation of Phase Specific Cost Driver

29. Contributions of Inspection Model Demonstrated dynamic effects of performing inspections. New knowledge regarding interrelated factors of inspection effectiveness. Demonstrated complementary features of static and dynamic models. Techniques adopted in industry.

30. Abdel-Hamid Integrated Project Model

31. Abdel-Hamid Model Behavior

32. QA Policy Tradeoff Analysis

33. Planning

34. Human Resources

35. Estimation

36. Manpower Allocation

37. Testing

38. Control (1/2)

39. Control (2/2)

40. Quality Assurance

41. Software Development Productivity

42. Software Development