Modelling and analysing risk is one of the most critical activity in system engineering. However, in literature approaches like Fault Tree Analysis, Event Tree Analysis, Failure Modes and Criticality Analysis focus on the system-to-be without considering the impact of the associated risks to the organization where the system will operate. The Tropos framework has been proved effective in modell...

The importance analysis provides a means of analyzing the contribution of potential low-level system failures to identify and assess vulnerabilities of safety-critical systems. Common approaches attempt to enhance the system safety by addressing vulnerabilities using an iterative analysis process, while considering relevant constraints, e.g., cost, for optimizing the improvements. Typically, da...

Conventional fault tree analysis in safety analysis of complex engineering systems calculates the occurrence probability of the top undesired event using probabilistic failure rates. However, it is often very difficult to obtain those failure rates well in advance due to insufficient data, environment changing or new components. Fuzzy numbers can be applied to estimate failure rates by handling...

As programmable logic controllers (PLCs) are often used to implement safety–critical embedded software, safety demonstration of PLC code is needed. In this paper, we propose a fault tree analysis technique on Function Block Diagrams (FBDs) which is one of the most widely used PLC programming languages. FBD is currently being used to develop Reactor Protection System (RPS) for a nuclear power pl...

Fault diagnosis on a gear box is a difficult problem due to the non-stationary type of vibration signals it generates. Usually, one method of fault diagnosis can only inspect one corresponding fault category. Vibration based condition monitoring using machine learning methods is gaining momentum. In this paper, rough sets theory, is used to diagnose the fault gears in a gear box. Through the an...

This paper discusses the modeling and analysis of three major fault-tolerant software system architec-tures: DRB (Distributed Recovery Blocks), NVP (N-Version Programming) and NSCP (N Self-Checking Programming). In the system-level reliability modeling domain, fault tree analysis techniques and Markov reward modeling techniques are combined to incorporate transient and permanent hardware faults...

Radical Maintenance (RM) takes the root causes of failures as executive objects to make maintenance decisions. A Root Cause Analysis (RCA) is carried out on the function failure of equipment to performRMand to create a maintenance plan using the combined methods of Failure Mode, Effects and Criticality Analysis (FMECA), and Fault Tree Analysis (FTA). Evaluation criteria andmatrixes of criticali...

Classical combinatorial fault trees can be used to assess combinations of failures but are unable to capture sequences of faults, which are important in complex dynamic systems. A number of proposed techniques extend fault tree analysis for dynamic systems. One of such technique, Pandora, introduces temporal gates to capture the sequencing of events and allows qualitative analysis of temporal f...