Hichem Boudali

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Dependability tools are becoming an indispensable tool for modeling and analyzing (critical) systems. However the growing complexity of such systems calls for increasing sophistication of these tools. Dependability tools need to not only capture the complex dynamic behavior of the system components, but they must be also easy to use, intuitive, and(More)
Dynamic fault trees (DFT) extend standard fault trees by allowing the modeling of complex system components' behaviors and interactions. Being a high level model and easy to use, DFT are experiencing a growing success among reliability engineers. Unfortunately, a number of issues still remains when using DFT. Briefly, these issues are (1) a lack of(More)
Fault trees (FTs) are among the most prominent formalisms for reliability analysis of technical systems. Dynamic FTs extend FTs with support for expressing dynamic dependencies among components. The standard analysis vehicle for DFTs is state-based, and treats the model as a continuous-time Markov chain (CTMC). This is not always possible, as we will(More)
We present a continuous-time Bayesian network (CTBN) framework for dynamic systems reliability modeling and analysis. Dynamic systems exhibit complex behaviors and interactions between their components; where not only the combination of failure events matters, but so does the sequence ordering of the failures. Similar to dynamic fault trees, the CTBN(More)
This paper proposes a formally well-rooted and extensible framework for dependability evaluation: Arcade (architectural dependability evaluation). It has been designed to combine the strengths of previous approaches to the evaluation of dependability. A key feature is its formal semantics in terms of input/output-interactive Markov chains, which enables(More)
We present <i>DFTSim</i>, a simulation tool for dynamic fault trees (DFT). The simulation is carried out by directly sampling the failure distributions attached to the leaves (called basic events) of the tree and propagating the failure times upwards in the tree. Sampling the distributions of the DFT leaves is however not obvious. To sample from the(More)
Dynamic fault trees (DFTs) are a versatile and common formalism to model and analyze the reliability of computer-based systems. This paper presents a formal semantics of DFTs in terms of input/output interactive Markov chains (I/O-IMCs), which extend continuous-time Markov chains with discrete input, output and internal actions. This semantics provides a(More)
Non-functional properties, such as timeliness, resource consumption and reliability are of crucial importance for today&#x02019;s software systems. Therefore, it is important to know the non-functional behavior before the system is put into operation. Preferably, such properties should be analyzed at design time, at an architectural level, so that changes(More)
Dynamic Fault Trees in Reliability Engineering. Reliability and availability measures, such as system failure probability during a given mission time and system meantime-between-failures, are often important measures to assess in embedded systems design. There exist several techniques and formalisms for reliability/availability assessment. One such(More)