scholarly journals Dependability analysis of systems with on-demand and active failure modes, using dynamic fault trees

2002 ◽  
Vol 51 (2) ◽  
pp. 240-251 ◽  
Author(s):  
L. Meshkat ◽  
J.B. Dugan ◽  
J.D. Andrews
Keyword(s):  
Failure Modes ◽  
Fault Trees ◽  
On Demand ◽  
Dependability Analysis

Automatic Fault Tree Generation From Multidisciplinary Dependency Models for Early Failure Propagation Assessment

2018 ◽  
Author(s):  
Nikolaos Papakonstantinou ◽  
Joonas Linnosmaa ◽  
Jarmo Alanen ◽  
Bryan O'Halloran
Keyword(s):  
Failure Modes ◽  
Cooling System ◽  
Fault Tree ◽  
System Engineering ◽  
Automatic Generation ◽  
Worst Case ◽  
Fault Trees ◽  
Starting Point ◽  
Failure Propagation ◽  
Event Trees

Safety engineering for complex systems is a very challenging task and the industry has a firm basis and trust on a set of established methods like the Probabilistic Risk Assessment (PRA). New methodologies for system engineering are being proposed by academia, some related to safety, but they have a limited chance for successful adoption by the safety industry unless they provide a clear connection and benefit in relation to the traditional methodologies. Model-Based System Engineering (MBSE) has produced multiple safety related applications. In past work system models were used to generate event trees, failure propagation scenarios and for early human reliability analyses. This paper extends previous work, on a high-level interdisciplinary system model for early defense in depth assessment, to support the automatic generation of fault tree statements for specific critical system components. These statements can then be combined into fault trees using software already utilized by the industry. The fault trees can then be linked to event trees in order to provide a more complete picture of an initiating event, the mitigating functions and critical components that are involved. The produced fault trees use a worst-case scenario approach by stating that if a dependency exists then the failure propagation is certain. Our proposed method doesn’t consider specific failure modes and related probabilities, a safety expert can use them as a starting point for further development. The methodology is demonstrated with a case study of a spent fuel pool cooling system of a nuclear plant.

A MULTIFORMALISM MODULAR APPROACH TO ERTMS/ETCS FAILURE MODELING

2014 ◽  
Vol 21 (01) ◽  
pp. 1450001 ◽  
Author(s):  
FRANCESCO FLAMMINI ◽  
STEFANO MARRONE ◽  
MAURO IACONO ◽  
NICOLA MAZZOCCA ◽  
VALERIA VITTORINI
Keyword(s):  
Failure Modes ◽  
Stochastic Petri Nets ◽  
System Level ◽  
Design Parameters ◽  
Modular Approach ◽  
Reference Architecture ◽  
Critical Systems ◽  
Fault Trees ◽  
Availability Analysis ◽  
Railway Traffic

European Railway Traffic Management System/European Train Control System (ERTMS/ETCS) is a recent standard aimed at improving performance, safety and inter-operability of modern railways. In order to be compliant to ERTMS/ETCS, a railway signalling system must meet strict nonfunctional requirements on system level failure modes. In this paper, a multiformalism model is employed to perform an availability analysis of an ERTMS/ETCS reference architecture at early phases of its development cycle. At this aim, a bottom-up analysis is performed from subsystem failure models (expressed by means of Generalized Stochastic Petri Nets, Fault Trees and Repairable Fault Trees) up to the overall system model. The modular approach, here used, allows to evaluate the influence of basic design parameters on the probability of system-level failure modes and demonstrates that system availability is within the bound required by the ERTMS/ETCS specification. The results show that the multiformalism modeling approach helps to cope with complexity, eases the verification of availability requirements and can be successfully applied to the analysis of complex critical systems.

Uncertainty analysis of common cause failure in safety instrumented systems

2011 ◽  
Vol 225 (4) ◽  
pp. 450-460 ◽  
Author(s):  
W Mechri ◽  
C Simon ◽  
K Ben Othman
Keyword(s):  
Fuzzy Numbers ◽  
Epistemic Uncertainty ◽  
Monte Carlo Sampling ◽  
Fault Trees ◽  
Common Cause ◽  
Common Cause Failure ◽  
On Demand ◽  
Safety Integrity Level ◽  
Imperfect Knowledge ◽  
The Common

This paper analyses the problem of epistemic uncertainty in assessing the performance of safety instrumented systems (SIS) using fault trees. The imperfect knowledge concerns the common cause failure (CCF) involved in the SIS in low demand mode. The point-valued CCF factors are replaced by fuzzy numbers, allowing experts to express their uncertainty about the CCF values. This paper shows how these uncertainties propagate through the fault tree and how this induces an uncertainty to the values of the SIS failure probability on demand and to the safety integrity level of the SIS. For the sake of verification and comparison, and to show the exactness of the approach, a Monte Carlo sampling approach is proposed, where by a uniform or triangular second-order probability distribution of CCF factors is considered.

Causal and Fault Trees Analysis of Proton Exchange Membrane Fuel Cell Degradation

2015 ◽  
Vol 12 (5) ◽  
Author(s):  
Kais Brik ◽  
Faouzi Ben Ammar ◽  
Abdesslam Djerdir ◽  
Abdellatif Miraoui
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Internal State ◽  
Cell Model ◽  
Proton Exchange ◽  
Fault Trees ◽  
Dependability Analysis ◽  
Cell Energy ◽  
Conversion Performance ◽  
Exchange Membrane

This paper presents a reliability approach to analyze the degradation of proton exchange membrane fuel cell. This approach is based on the dependability analysis tools such as the causal and fault trees to establish an analysis of the internal state of the fuel cell energy conversion performance and evaluate its lifetime. The elaboration of causal tree offers powerful tools to a deductive analysis, which consists on seeking the various combinations of events leading to the fuel cell degradation. The parameters of fuel cell model are identified in order to found the degree of degradation. The experimental determination of the variation interval of the parameters is done according to each of degradation modes. A diagnostic method is proposed in order to identify the depth of each aging process of the fuel cell. The diagnosis is done by comparing the experimental output characteristic at beginning of life of the fuel cell with the used fuel cell to qualify and quantify the depth of degradation.

Characterization of the Quasi-static Deformation of LAAG Joints Adhering Machined Steel Surfaces

2005 ◽  
Vol 127 (2) ◽  
pp. 350-357 ◽  
Author(s):  
Edward C. De Meter
Keyword(s):  
Static Loading ◽  
Steel Surface ◽  
Failure Modes ◽  
Axial Loading ◽  
Adhesive Bond ◽  
Shear Loading ◽  
Adhesive Joints ◽  
On Demand ◽  
Steel Surfaces

Light Activated Adhesive Gripper (LAAG) workholding technology is a means by which a workpiece is held by adhesive joints that can be instantaneously cured or destroyed, on demand. A LAAG joint is the adhesive bond between the gripper pin and workpiece. Due to the novelty of this concept, no knowledge exists with regard to how LAAG joints deform and fail during quasi-static loading. This paper describes an investigation that was carried out to characterize the strength, ductility, and failure modes of a LAAG joint adhering a machined, steel surface subject to axial loading and shear loading.

scholarly journals Automation of Aseptic Sterile Preparation: Risk Analysis and Productivity Comparison with Manual Process

2019 ◽  
Vol 4 (1) ◽  
pp. 15-28 ◽  
Author(s):  
Jeanne Heloury ◽  
Guillaume Bouguéon ◽  
Thomas Deljehier ◽  
Audrey Jourand ◽  
Aude Berroneau ◽  
...  
Keyword(s):  
Risk Analysis ◽  
Control Systems ◽  
Failure Modes ◽  
Bulk Solution ◽  
Automatic Process ◽  
Robot Design ◽  
Time Analysis ◽  
Worst Case ◽  
On Demand ◽  
Criticality Analysis

Abstract Two automation methods for aseptic preparation in hospital pharmacy, robot and peristaltic pump, were compared to manual process both for risk analysis using Failure Modes Effects and Criticality Analysis (FMECA) method and for productivity using time analysis grids built for each process. The results obtained with the different workflow organizations showed that the worst-case conditions for productivity was production “on demand” of tailor-made preparations. in that case, the manual process was not significantly different from the robotic process (p-value=0.72). For the standardized preparations, the semi-automatic process preparing a batch from bulk solution from “to be reconstituted” drugs was significantly superior to the robotic process preparing repetitive series of doses (p-value<0.01). Productivity of the robot was dramatically increased when the robot performed standardized preparations either from ready to use solutions or mixed cycles due to the robot design. When different processes were FMECA analyzed for risk analysis the robotic process was found as the safer process in comparison to others with a total of Criticality Indexes of 1060, 719, 656 for manual, semi-automatic and robot, respectively. Except for the robotic, semi-automatic and manual processes needed additional IT control systems to limit the risk of failures.

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