System of systems dependability – Theoretical models and applications examples

• A framework for evaluation of system of systems dependability is presented.
• The model is based on the service continuity concept and consists of two parts.
• The static part can be created as a fuzzy logic-oriented advisory expert system.
• The dynamic, risk oriented part, is related to the concept of throughput chain.
• A new definition of dependability engineering is proposed.

The aim of this article is to generalise the concept of "dependability" in a way, that could be applied to all types of systems, especially the system of systems (SoS), operating under both normal and abnormal work conditions. In order to quantitatively assess the dependability we applied service continuity oriented approach. This approach is based on the methodology of service engineering and is closely related to the idea of resilient enterprise as well as to the concept of disruption-tolerant operation. On this basis a framework for evaluation of SoS dependability has been developed in a static as well as dynamic approach. The static model is created as a fuzzy logic-oriented advisory expert system and can be particularly useful at the design stage of SoS. The dynamic model is based on the risk oriented approach, and can be useful both at the design stage and for management of SoS. The integrated model of dependability can also form the basis for a new definition of the dependability engineering, namely as a superior discipline to reliability engineering, safety engineering, security engineering, resilience engineering and risk engineering.