DFTCalc Tool for Computing Failure Probability of Dynamic Fault Trees

Organisation:	University of Twente (THE NETHERLANDS)
Functionality:	Compute the failure probability of DFTs.
Tools used:	CORAL MRMC CADP (Construction and Analysis of Distributed Processes)
Period:	2012
Description:	During the design of a mission-critical component-based system one has to take failures into account. One way to model the failure of a component-based system is by using Dynamic Fault Trees (DFT). A DFT describes the dependencies (edges) the components (nodes) have on each other on multiple levels. Each leaf-node describes a basic component or event and other nodes describe part of the system comprised of one or more basic components or events. With this knowledge, the failure rate of the whole system can be calculated. The DFTCalc tool for calculating the failure probability of a DFT follows the same approach as the CORAL tool, which generates I/O-IMCs by using an intermediate translation into LOTOS. The main differences between the two are that (a) DFTCalc uses the newer LNT language to describe the building blocks; (b) DFTCalc generates an EXP network of automata to glue the building blocks together; (c) DFTCalc is built to support future dynamic additions, such as repair rates. Experiments have shown that DFTCalc is about twice as fast as CORAL. The reason for this speed up can be attributed to several aspects, a major difference being due to the use of smart composition available in SVL, which optimizes the composition of the individual IMCs to the complete IMC representing the DFT.
Conclusions:	Using LNT as the language to model individual nodes in the DFT leads to clean code without sacrificing expressiveness. Future work includes adding repair rates (by extending the implementation of the individual nodes and the EXP glue code) and adding more functionalities (e.g., for calculating averages and evidence).
Publications:	[VanDerBerg-12] Freark van der Berg. "DFTCalc - Calculating DFTs using Lotos NT". Technical Report, University of Twente, May 2012. Available from the CADP Web site in PDF or PostScript [Arnold-Belinfante-vanderBerg-Guck-Stoelinga-13-a] Florian Arnold, Axel Belinfante, Freark Van der Berg, Dennis Guck, and Marielle Stoelinga. "DFTCalc: A Tool for Efficient Fault Tree Analysis". Proceedings of the 32nd International Conference on Computer Safety, Reliability, and Security (SAFECOMP'2013), Toulouse, France, Lecture Notes in Computer Science, volume 8153, pp. 293-301, September 2013. Available on-line at: http://eprints.eemcs.utwente.nl/23820/ or from the CADP Web site in PDF or PostScript [Arnold-Belinfante-vanderBerg-Guck-Stoelinga-13-b] Florian Arnold, Axel Belinfante, Freark Van der Berg, Dennis Guck, and Marielle Stoelinga. "DFTCalc: A Tool for Efficient Fault Tree Analysis (extended version)". Technical Report, Centre for Telematics and Information Technology, University of Twente, Enschede, July 2013. Available on-line at: http://eprints.eemcs.utwente.nl/23404/ or from the CADP Web site in PDF or PostScript [Guck-Spel-Stoelinga-15] Dennis Guck, Jip Spel, and Marielle Stoelinga. "DFTCalc: Reliability Centered Maintenance via Fault Tree Analysis". 17th International Conference on Formal Engineering Methods (ICFEM'2015), Paris, France, Lecture Notes in Computer Science, volume 9407, pp. 304-311, November 2015. Available on-line at: http://eprints.eemcs.utwente.nl/26146/ or from the CADP Web site in PDF or PostScript
Contact:	Marielle Stoelinga Formal Methods and Tools Group University of Twente P.O. Box 217 7500 AE Enschede The Netherlands Tel: +31 53 489 3773 Fax: +31 53 489 3247 Email: marielle@cs.utwente.nl
Further remarks:	This tool, amongst others, is described on the CADP Web site: http://cadp.inria.fr/software

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