Huy T. Tran

A framework for the quantitative assessment of performance-based system resilience

Increasing system complexity and threat uncertainty require the consideration of resilience in the design and analysis of engineered systems. While the resilience engineering community has begun to converge on a definition and set of characteristics for resilience, methods for quantifying the concept are still limited in their applicability to system designers. This paper proposes a framework for assessing resilience that focuses on the ability of a system to absorb disruptions, recover from them, and adapt over time. The framework extends current approaches by explicitly considering temporal aspects of system responses to disruptions, volatility in system performance data, and the possibility of multiple disruption events. Notional system performance data is generated using the logistic function, providing an experimental platform for a parametric comparison of the proposed resilience metric with an integration-based metric. An information exchange network model is used to demonstrate the applicability of the framework towards system design tradeoff studies using stochastic simulations. The presented framework is domain-agnostic and flexible, such that it can be applied to a variety of systems and adjusted to focus on specific aspects of resilience.

Evaluating the agility of adaptive command and control networks from a cyber complex adaptive systems perspective

Command and control (C2) networks are critical components of modern military systems, enabling information sharing and communications between systems. These systems operate in complex environments characterized by uncertain and evolving threats, creating a need for agile C2 networks. This paper presents a Cyber Complex Adaptive Systems approach for assessing the agility of adaptive C2 networks. Agent-based modeling is used to simulate the performance of a C2 network connecting unmanned aerial vehicles for a collaborative surveillance mission. Due to the importance of information sharing in C2, information entropy-based awareness is used to quantitatively evaluate C2 performance. Complex network methods are used to define initial network topologies and threats. Network adaptation through random rewiring is shown to recover lost C2 capabilities following network attacks, and in some cases improve performance relative to initial topologies. Inverse average path length and largest connected component fraction are shown to be important factors for maintaining C2 awareness, with inverse average path length being the better indicator of awareness.

Metrics-based analysis and evaluation framework for engineering resilient systems

The DoDs ERS initiative calls for affordable, effective, and adaptable systems development. In support of this, a metrics-based analysis framework is introduced to address certain challenges for the design of future C2 military System-of-Systems (SoS). The interpretation of the concept of resilience, as well as a supporting threat analysis procedure for military SoS applications, have been the key driver for the evaluation of a systems ability to maintain its mission capability and health, when under attack due to given threats. An agent-based C2 UAV communication network application has been developed for the demonstration of the framework. Scenario-based case studies that involved communication jamming by the adversary forces are introduced for the evaluation the C2 systems response to a threat, including both degradation and recovery periods.

Designing resilient system-of-systems networks

The networked nature of many system-of-systems (SoS) requires consideration of resilience in their design and analysis. We present an approach for the design space exploration of such resilient SoS networks. We model candidate network designs using complex network methods, and generate and analyze a network design space with Design of Experiments. Results show an interaction between adaptation strategy and threat type, indicating that the best adaptation strongly depends on the threat faced. However, no interaction is seen with initial topology, suggesting that random initial topologies provide more resilience than scale-free ones regardless of the threat or adaptation strategy.

A system-of-systems approach for assessing the resilience of reconfigurable command and control networks

Increasing complexity and connectivity of military systems has created a need to investigate novel Command and Control (C2) approaches. In addition to being effective, C2 approaches must also be resilient to handle operating conditions characterized by uncertainty and mission volatility. This paper proposes an SoS approach to assessing C2 resilience, focusing on C2 architectures defined by information sharing and decision authority networks. Network reconfiguration based on random rewiring is used to improve the resilience of C2 architectures. C2 capability is measured by information entropy-based battlespace awareness and used as the primary metric for evaluating the resilience of C2 architectures. Awareness results are supplemented by complex network metrics to provide additional insights into the behavior of C2 architectures. An agent-based simulation of a network-centric unmanned aerial vehicle surveillance mission is used to simulate C2 architecture performance. Results show that random rewiring improves the resilience of C2 architectures to random and targeted node removal. Network largest component size is shown to accurately predict the awareness of a C2 architecture, indicating that C2 resilience can be achieved by maintaining network connectivity. Algebraic connectivity and inverse average path length also show similar trends to awareness. These results suggest the use of connectivity and path length network metrics to design reconfiguration strategies for C2 resilience.