Operads for complex system design specification, analysis and synthesis

As the complexity and heterogeneity of a system grows, the challenge of specifying, documenting and synthesizing correct, machine-readable designs increases dramatically. Separation of the system into manageable parts is needed to support analysis at various levels of granularity so that the system is maintainable and adaptable over its life cycle. In this paper, we argue that operads provide an effective knowledge representation to address these challenges. Formal documentation of a syntactically correct design is built up during design synthesis, guided by semantic reasoning about design effectiveness. Throughout, the ability to decompose the system into parts and reconstitute the whole is maintained. We describe recent progress in effective modelling under this paradigm and directions for future work to systematically address scalability challenges for complex system design.

Understanding the Impact of Decision Making on Robustness During Complex System Design: More Resilient Power Systems

Robust design strategies continue to be relevant during concept-stage complex system design to minimize the impact of uncertainty in system performance due to uncontrollable external failure events. Historical system failures such as the 2003 North American blackout and the 2011 Arizona-Southern California Outages show that decision making, during a cascading failure, can significantly contribute to a failure's magnitude. In this paper, a scalable, model-based design approach is presented to optimize the quantity and location of decision-making agents in a complex system, to minimize performance loss variability after a cascading failure, regardless of where the fault originated in the system. The result is a computational model that enables designers to explore concept-stage design tradeoffs based on individual risk attitudes (RA) for system performance and performance variability, after a failure. The IEEE RTS-96 power system test case is used to evaluate this method, and the results reveal key topological locations vulnerable to cascading failures, that should not be associated with critical operations. This work illustrates the importance of considering decision making when evaluating system level tradeoffs, supporting robust design.

Integrating Security Requirements Engineering into MBSE: Profile and Guidelines

Model-Based System Engineering (MBSE) provides a number of ways on how to create, validate, and verify the complex system design; unfortunately, the inherent security aspects are addressed neither by the SysML language that is the main MBSE enabler nor by popular MBSE methods. Although there are many common points between MBSE and security requirements engineering, the key advantages of MBSE (such as managed complexity, reduced risk and cost, and improved communication across a multidisciplinary team) have not been exploited enough. This paper reviews security requirements engineering processes and modeling methods and standards and provides the MBSE security profile as well, which is formalized with the UML 2.5 profiling capability. The new UML-based security profile conforms to the ISO/IEC 27001 information security standard. In addition to the MBSE security profile, this paper also presents the security profile application use case and the feasibility study of current status for security and systems engineering processes.