Multi-epoch analysis allows a decision-maker to evaluate metrics between and across epochs to gauge the impact of uncertainties on system value. This includes the evaluation of short run passive and active strategies for achieving value sustainment such that systems can maintain value delivery across different missions or changing contexts. A system that is passively robust is insensitive to changing conditions and continues to deliver acceptable value. Alternatively, a system that suffers deterioration in value due to evolving conditions may benefit from the use of change options that make them flexible, adaptable or resilient. The example shown here provides an example of how an interactive application can be used during changeability analysis.
When determining the changeability of a design a metric that is often examined is filtered outdegree (FOD). Outdegree counts how many available end state designs can be reached by exercising the use of change options. A decision-maker will likely want to apply filters to restrict the allowable change time or costs associated with change as was done for a few hand-picked cases by Fitzgerald [1]. Different stakeholders may have different preferences for allowable change time and cost or may need help understanding how restrictions they place on these variables constrain the space of available designs. The application shown below demonstrates how these types of changeability analysis questions can be examined via an interactive application. As described in [2,3] the interactive visualizations shown below applies Online Analytical Processing (OLAP), multiple coordinated views and binned aggregation to allow an analyst to concurrently trade design variables and operational variables against cost and FOD. Note that while this example uses a data set with only 384 designs to consider it can easily scale to examine thousands or millions of data points.
[1] Fitzgerald, M.E., Managing Uncertainty in Systems with a Valuation Approach for Strategic Changeability, Master of Science Thesis, Aeronautics and Astronautics, MIT, June 2012.
[2] Curry, M, and Ross, A.M., "Considerations for an Extended Framework for Interactive Epoch-Era Analysis," 13th Conference on Systems Engineering Research, Hoboken, NJ, March 2015.
[3] Curry, M, and Ross, A.M., "Designing for System Value Sustainment using Interactive Epoch Era Analysis: A Case Study for On-orbit Servicing Vehicles," 14th Conference on Systems Engineering Research, Huntsville, AL, March 2016.