DFTCalc: Reliability Centered Maintenance via Fault Tree Analysis (Tool Paper)

Guck, Dennis; Spel, Jip; Stoelinga, Mariëlle

doi:10.1007/978-3-319-25423-4_19

Cited by 25 publications

(28 citation statements)

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“…acting before component failure [20]. In [13] a tool is presented to compute RAMS metrics from DFTs in the presence of a maintenance policy. FMTs offer a formalism for this: They are a superset of DFTs which can model and assess various maintenance concepts [19].…”

Section: Preliminariesmentioning

confidence: 99%

Modelling Smart Buildings Using Fault Maintenance Trees

Abate

Budde

Cauchi

et al. 2018

Computer Performance Engineering

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Increasingly many industrial spheres are enforced by law to satisfy strict RAMS requirements-reliability, availability, maintainability, and safety. Applied to Fault Maintenance Trees (FMTs), formal methods offer flexible and trustworthy techniques to quantify the resilience of (abstract models of) systems. However, the estimated metrics are relevant only as far as the model reflects the actual system: Refining an abstract model to reduce the gap with reality is crucial for the usefulness of the results. In this work, we take a practical approach at the challenge by studying a Heating, Ventilation and AirConditioning unit (HVAC), ubiquitous in smart buildings. Using probabilistic and statistical model checking, we assess RAMS metrics of a basic fault maintenance tree HVAC model. We then implement four modifications augmenting the expressivity of the FMT model, and show that reliability, availability, expected number of failures, and costs, can vary by orders of magnitude depending on involved modelling details.

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Section: Preliminariesmentioning

confidence: 99%

Modelling Smart Buildings Using Fault Maintenance Trees

Abate

Budde

Cauchi

et al. 2018

Computer Performance Engineering

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“…The tree inFig. 2models a railway-signal system, which fails if its high voltage and relay cabinets fail[25,46].…”

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confidence: 99%

Rare Event Simulation for Non-Markovian Repairable Fault Trees

Budde

Biagi

Monti

et al. 2020

Tools and Algorithms for the Construction and Analysis of Systems

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Dynamic fault trees (dft) are widely adopted in industry to assess the dependability of safety-critical equipment. Since many systems are too large to be studied numerically, dfts dependability is often analysed using Monte Carlo simulation. A bottleneck here is that many simulation samples are required in the case of rare events, e.g. in highly reliable systems where components fail seldomly. Rare event simulation (res) provides techniques to reduce the number of samples in the case of rare events. We present a res technique based on importance splitting, to study failures in highly reliable dfts. Whereas res usually requires meta-information from an expert, our method is fully automatic: By cleverly exploiting the fault tree structure we extract the so-called importance function. We handle dfts with Markovian and non-Markovian failure and repair distributions-for which no numerical methods existand show the efficiency of our approach on several case studies. Fault trees.A fault tree (ft) describes how component failures occur and propagate through the system, eventually leading to system failures. Technically, an ft is a directed acyclic graph whose leaves model component failures, and $ This work was partially funded by NWO, NS, and ProRail project 15474 (SE-whose other nodes (called gates) model failure propagation. Using fault trees one can compute dependability metrics to quantify how a system fares w.r.t. certain performance indicators. Two common metrics are system reliability-the probability that there are no system failures during a given mission time-and system availability-the average percentage of time that a system is operational.Static fault trees (aka standard fts) contain a few basic gates, like AND and OR gates. This makes them easy to design and analyse, but also limits their expressivity. Dynamic fault trees (dfts [21,52]) are a common and widely applied extension of standard fts, catering for more complex dependability patterns, like spare management and causal dependencies. To model these patterns, dfts come with additional gates, for instance SPARE, PAND, and FDEP.Such gates make dfts more difficult to analyse. In static fts it only matters whether or not a component has failed, so they can be analysed with Boolean methods, such as binary decision diagrams [32]. Dynamic fault trees, on the other hand, crucially depend on the failure order, so Boolean methods are insufficient. Moreover and on top of these two classes, repairable fault trees (rft [7]) permit components to be repaired after they have failed. This is crucial to model faulttolerant systems more realistically. Yet repairs make analyses even harder: it does not suffice to know which components failed, or in which order, but also if they are simultaneously failed. The general rule is that the more complex the formalism, the more realistic the model, and the harder the analyses. Fig. 2 is an rft with a top AND gate, a SPARE (Rcab), and three leaves.Fault tree analysis. The reliability/availability of a fault tree can be computed via...

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“…The industrial case models a redundant system of relays and high-voltage cabinets used in railway signalling, and was taken from [GSS15]. The other two cases are the fault-tolerant parallel processor (FTPP) [DBB90] and the hypothetical example computer system (HECS) [SVD + 02].…”

Section: Case Studies and Resultsmentioning

confidence: 99%

“…This case, provided by the consulting company Movares in [GSS15], is a model of a redundant system of relay and high-voltage cabinets used in railway signalling.…”

Section: Railway Cabinetsmentioning

confidence: 99%

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Zen and the Art of Railway Maintenance

Ruijters¹

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DFTCalc: Reliability Centered Maintenance via Fault Tree Analysis (Tool Paper)

Cited by 25 publications

References 16 publications

Modelling Smart Buildings Using Fault Maintenance Trees

Modelling Smart Buildings Using Fault Maintenance Trees

Rare Event Simulation for Non-Markovian Repairable Fault Trees

Zen and the Art of Railway Maintenance

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