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Giffin M., de Weck O., Bounova G., Keller R., Eckert C., Clarkson J., “Change Propagation Analysis in Complex Technical Systems”, DETC2007-34652, ASME 2007 Design Engineering Technical Conferences, DETC2007-34871, Las Vegas, NV, September 4-7, 2007
In Press: ASME Journal of Mechanical Design
Sponsor: Raytheon Integrated Defense Systems
ProblemAddressed
Understanding change propagation patterns in large technicalprojects involving hardware, software and human operators
ScientificContribution
Developed procedure for data-mining of a large change request database (9 years, 41,500 changes) and analyzing change patterns (“motifs”) as well as classification of system components with a Change Propagation Index (CPI)
Outcome, Impact Applied to a large USAF Radar System project at Raytheon. Identified areas that are likely candidates for flexibility infusion
Areas found to be strong multipliers 16: hardware performance evaluation 25: hardware functional evaluation 5: core data processing logic 32: system evaluation tools 19: common software services 3: graphical user interface (GUI)
Areas found to be perfect reflectors 27, 41: look like perfect absorbers but actually zero changes implemented despite numerous changes proposed = perfect reflectors
Insights Inverse relationship between change magnitude and frequency of occurrence
Large changes are infrequent, small ones are ubiquitous
Many change requests are never implemented Some are rejected, others are ignored (~ 50%)
Changes may form complex networks over time. Most are small (<10 changes), a few large ones exist (beware of these !) Change networks form through coalescence and not necessarily through multi-
step causal change propagation
Changes can propagate between areas that are not direct neighbors in the system DSM (not shown here, but we found this is so)
Subsystems can be classified as: Multipliers CPI > ~0.3 Carriers -0.1<CPI<1.0 Absorbers CPI<-0.3
Reflectors of Change CRI>CAI Acceptors of Change CAI>CRI
Analysis of change database revealed that Real world change processes more complex than expected Industry data tends to be “noisy” Potential for deriving change impact and likelihood for future projects
Data Processing: Standardize methods for recording and processing data, tracing large change
networks in greater depth- attempt to reconstruct logic
Staffing and Organization: Analyze effects of staffing on changes and components Patterns based on which personnel/organization work on the changes?
Contractual: Can change propagation be used to write better prime and sub-contracts?
Statistical: Are there critical numbers for change propagation? Limits on the number of
propagation steps? .
CMI-Sponsored Workshop on Engineering ChangeMIT Endicott House, October 30-31, 2008~ 12 firms from various industries (aerospace, auto, printing, construction)
Problems discovered during production and operations in the field such as retrofits, recalls ….(melioration)
Customization of product variants for different customers and market segments (globalization)
Infusion of new technologies during product refreshes or major “block” upgrades (innovation)
Cost reduction Initiatives, response to new features introduced by other firms (competition)
New government regulations (e.g. fuel economy standards, no lead in electronics …(compliance)
Others ….?
Workshop Goals
Obtain multi-faceted industry perspective on state-of-the art in engineering change practice
Present academic perspective and recent research advances to industry
Establish a research agenda for the next 5 years Put in place basis for Special Issue of RED* Stimulate interest in follow-up collaboration Establish user community for advanced engineering change methods
and tools
* Research in Engineering Design (RED) Journal
Invited Companies
UK Rolls Royce (A/C
Engines)* Perkins (Diesel)* Volvo (Trucks, Engines)* BAE Systems (Defense)* Bosch (Auto Supplier)* BMW (Cars)* BP (Oil & Gas)* MAN Roland (Printing
Systems) Arup (Construction)
US Xerox (Printing Systems) Ford, GM (Cars and Trucks) Agusta Westland (Helicopters) Boeing (Aircraft) General Mills (Food) Fluor (Construction) Mack (Highway Trucks) Gerber (Textile Machines) NASA (Spacecraft) Raytheon (Defense Systems) Ventana Systems (S/W) Aberdeen Group United Technologies Corp.
Strategic Engineering is the process of designing systems and products in a way that deliberately accounts for customization and future uncertainties such that their lifecycle value is maximized.