An algebra of temporal faults

• Autor(a) principal: DIDIER, André Luís Ribeiro
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UFPE
• Texto Completo: https://repositorio.ufpe.br/handle/123456789/25855
• topic: Ciência da computação; Análise de falhas

Fault modelling is essential to anticipate failures in critical systems. Traditionally, Static Fault Trees are employed to this end, but Temporal and Dynamic Fault Trees have gained evidence due to their enriched power to model and detect intricate propagation of faults that lead to a failure. In a previous work, we showed a strategy based on the process algebra CSP and Simulink models to obtain fault traces that lead to a failure. From the fault traces we discarded the ordering information to obtain structure expressions for Static Fault Trees. Instead of discarding such an ordering information, it could be used to obtain structure expressions of Temporal or Dynamic Fault Trees. In this work we present: (i) an algebra of temporal faults (with a notion of fault propagation) to analyse systems’ failures, and prove that it is indeed a Boolean algebra, and (ii) a parametrized activation logic to express nominal and erroneous behaviours, including fault modelling, provided an algebra and a set of operational modes. The algebra allows us to inherit Boolean algebra’s properties, laws and existing reduction techniques, which are very beneficial for fault modelling and analysis. With expressions in the algebra of temporal faults we allow the verification of safety properties based on Static, Temporal or Dynamic Fault Trees. The logic created in this work can be combined with other algebras beyond those shown here. Being used with the algebra of temporal faults it is intended to help analysts to consider all possible situations in complex expressions with order-related operators, avoiding missing subtle (but relevant) faults combinations. Furthermore, our algebra of temporal faults tackles the NOT operator which has been left out in other works. We illustrate our work on simple but real case studies, some supplied by our industrial partner EMBRAER. Isabelle/HOL was used to mechanize the theorems proofs of the algebra of temporal faults.