Development Of Fault Trees Research Articles

Benchmarking the failure assessment of perishable product supply chain using fault tree approach: insights from apple case study of India

PurposeThe purpose of this paper is to facilitate perishable product supply chain (PPSC) managers and practitioners to assess PPSC failure events. The paper proposed fault tree methodology for assessing failures associated with PPSC for evaluating the performance in terms of effective PPSC management adoption.Design/methodology/approachInitially, different failure events were identified from literature and semi-structured interviews from experts. Fault tree model was developed from the identified failure events. Probability of failure events was calculated using Poisson distribution based on the annual reports and interviews conducted from experts. Further, qualitative analysis – minimum cut sets (MCSs), structural importance coefficient (SIC) – and quantitative analysis – Birnbaum importance measure (BIM), criticality importance factor (CIF) and diagnosis importance factor (DIF) – were performed for ranking of failure events. In this study, fault tree development and analysis were conducted on apple supply chain to present the authenticity of this method for failure analysis.FindingsThe findings indicate that the failure events, given as failure at production and procurement (A2), that is, involvement of middleman (BE3), handling and packaging failure (BE4) and transportation failure (A3), hold the highest-ranking scores in analysis of PPSC using fault tree approach.Originality/valueThis research uses the modularization approach for evaluation of failure events of PPSC. This paper explores failures related to PPSC for efficient management initiatives in apple supply chain context. The paper also provides suggestion from managerial perspective with respect to each failure event.

A generic approach to analysing failures in human – System interaction in autonomy

Autonomous systems operation will in the foreseeable future rely on the interaction between software, hardware and humans. Efficient interaction and communication between these agents are crucial for safe operation. Conventional methods for hazard identification and safety assessment focus often on one of the aspects of the system only, e.g., human reliability, software failures, or equipment reliability. The method Human-System Interaction in Autonomy (H-SIA) was recently proposed, focusing on autonomous ships operation and collision scenarios. H-SIA provides a framework for analyzing autonomous ship operation as an entirety, rather than each agent separately. The method comprised initially of two main elements: An Event Sequence Diagram (ESD) and a Concurrent Task Analysis (CoTA). While the ESD models the events that can take place following an initiating event, the CoTA models which tasks the agents must perform for these events to succeed. This paper extends H-SIA to include the paths to failure, through the development of Fault Trees (FTs), which is necessary for risk analysis and identification of risk reduction measures. The FTs development of H-SIA introduces novelties in comparison to common FTs: (i) they model the system as whole, (ii) they are generic and can accommodate a diversity of systems designs; (iii) they lead to basic failure events. The FTs allows for identification of failure events arising through interaction between autonomous ship and human operators, as well as failure propagation through these agents. The basic failure events are applicable for different autonomous concepts. A case study on autonomous ship collision demonstrates the use of the extended method. The case study illustrates H-SIA’s applicability to different designs and levels of autonomy, its potential for identification of failure events, and its use in risk assessments.

Analysis of human-induced initiating events in a multi-unit loss of offsite power scenario

ABSTRACTHuman-induced initiators (category-B actions) are the initiators that are caused by human errors and are rarely explicitly identified and modeled in probabilistic safety assessments (PSAs). The current concern over the safety of multi-unit nuclear power sites is also a motivation for this research. This study proposes a novel process for identifying and quantifying category-B actions and ultimately, how to derive a human-induced initiating event frequency in a multi-unit scenario. Hence, this study fundamentally applies a scenario–system–action search scheme using maintenance and testing procedures, quantifies the human error probability by using the cause-based decision tree and technique for human error rate prediction method, models category-B human actions in the developed fault trees, and derives the human-induced initiating event frequency. The procedure, which is used in this approach, essentially involves system analysis, fault tree development, human error identification, screening, and quantification. The multi-unit loss of offsite power is used as an example accident situation which illustrates the application of the suggested method. Hence, the human-induced initiating event frequency for the loss of off-site power scenario for two units is derived. The application of this method would advance the efforts concerning multi-unit nuclear power plant (NPP) site risk analysis.

Risk Analysis of a Fuel Storage Terminal Using HAZOP and FTA.

The size and complexity of industrial chemical plants, together with the nature of the products handled, means that an analysis and control of the risks involved is required. This paper presents a methodology for risk analysis in chemical and allied industries that is based on a combination of HAZard and OPerability analysis (HAZOP) and a quantitative analysis of the most relevant risks through the development of fault trees, fault tree analysis (FTA). Results from FTA allow prioritizing the preventive and corrective measures to minimize the probability of failure. An analysis of a case study is performed; it consists in the terminal for unloading chemical and petroleum products, and the fuel storage facilities of two companies, in the port of Valencia (Spain). HAZOP analysis shows that loading and unloading areas are the most sensitive areas of the plant and where the most significant danger is a fuel spill. FTA analysis indicates that the most likely event is a fuel spill in tank truck loading area. A sensitivity analysis from the FTA results show the importance of the human factor in all sequences of the possible accidents, so it should be mandatory to improve the training of the staff of the plants.

Methodology for computer aided fuzzy fault tree analysis

Probabilistic risk assessment (PRA) is a comprehensive, structured and logical analysis method aimed at identifying and assessing risks of complex process systems. PRA uses fault tree analysis (FTA) as a tool to identify basic causes leading to an undesired event, to represent logical dependency of these basic causes in leading to the event, and finally to calculate the probability of occurrence of this event. To conduct a quantitative fault tree analysis, one needs a fault tree along with failure data of the basic events (components). Sometimes it is difficult to have an exact estimation of the failure rate of individual components or the probability of occurrence of undesired events due to a lack of sufficient data. Further, due to imprecision in basic failure data, the overall result may be questionable. To avoid such conditions, a fuzzy approach may be used with the FTA technique. This reduces the ambiguity and imprecision arising out of subjectivity of the data. This paper presents a methodology for a fuzzy based computer-aided fault tree analysis tool. The methodology is developed using a systematic approach of fault tree development, minimal cut sets determination and probability analysis. Further, it uses static and dynamic structuring and modeling, fuzzy based probability analysis and sensitivity analysis. This paper also illustrates with a case study the use of a fuzzy weighted index and cutsets importance measure in sensitivity analysis (for system probabilistic risk analysis) and design modification.

Methodology for Computer-Aided Fault Tree Analysis

Fault tree analysis is a systematic, deductive and probabilistic risk assessment tool which elucidates the causal relations leading to a given undesired event. Quantitative fault tree (failure) analysis requires a fault tree and failure data of basic events. Development of a fault tree and subsequent analysis require a great deal of expertise, which may not be available all the time. Computer-aided fault tree analysis is an easy-to-use approach, which not only provides reliable results but also facilitates the validation and repeatability of the analysis. This enhances the overall results of the fault tree analysis and quantitative risk analysis. This paper presents a revised methodology for computer-aided fault tree analysis. The methodology includes fault tree development, minimal cutsets determination, cutsets optimization and probability analysis. The methodology uses advanced concepts of fault tree development and static and dynamic modularizing for complex and large fault trees. Furthermore, it enables sensitivity analysis of the system for design modification and risk-based decision making. Application of the proposed methodology to a process system is also discussed in the paper.

Development of Fault Trees for Risk Assessment of Dam Gates and Associated Operating Equipment

AbstractThis article deals with development of fault-trees for risk assessment of dam gates and associated operating equipment. The first part of the paper deals with background information leading to the selection of Lafitte Method as the preferred method for risk assessment. The article also discusses in detail the initiating events, consequential events, and the consequences, dealing with transient and persistent overtopping results of the sensitivity analysis along with a detailed list of various failure events, the associated failure modes and their cause/effect dealing with dam gates. Actual detailed fault-trees for dam gates and associated operating equipment are presented.

Development of Fault Trees for Risk Assessment of Dam Gates and Associated Operating Equipment

This article deals with development of fault-trees for risk assessment of dam gates and associated operating equipment. The first part of the paper deals with background information leading to the selection of Lafitte Method as the preferred method for risk assessment. The article also discusses in detail the initiating events, consequential events, and the consequences, dealing with transient and persistent overtopping results of the sensitivity analysis along with a detailed list of various failure events, the associated failure modes and their cause/effect dealing with dam gates. Actual detailed fault-trees for dam gates and associated operating equipment are presented.

System Hazard Analysis of the Selespeed Gearbox

This paper presents a method for the risk assessment of complex systems, with particular attention to the automotive field. It relies on a preliminary top-down analysis, similar to the one adopted in the development of Fault Trees, aimed at providing a graphical, high level, representation of the system functional dependencies and of the failure propagation paths. The resulting graph is pruned to consider any system failure, or top event, in any operating mode of interest and to isolate the components failures, or basic events, causing it. Finally, this information is collected in a Failure Mode and Effect Analysis (FMEA) table, which represents the final result of the procedure. The approach proposed has been used here to complete the hazard analysis of an automated manual gearbox.

Analysis and synthesis of the behaviour of complex programmable electronic systems in conditions of failure

This paper introduces a new method for safety analysis which modifies, automates and integrates a number of classical safety analysis techniques to address some of the problems currently encountered in complex safety assessments. The method enables the analysis of a complex programmable electronic system from the functional level through to low levels of its hardware and software implementation. In the course of the assessment, the method integrates design and safety analysis and harmonises hardware safety analysis with the hazard analysis of software architectures. It also introduces an algorithm for the synthesis of fault trees, which mechanises and simplifies a large and traditionally problematic part of the assessment, the development of fault trees. In this paper, we present the method and discuss its application on a prototypical distributed brake-by-wire system for cars. We argue that the method can help us rationalise and simplify an inherently creative and difficult task and therefore gain a consistent and meaningful picture of how a complex programmable system behaves in conditions of failure. q 2001 Elsevier Science Ltd. All rights reserved.

PROFAT: A user friendly system for probabilistic fault tree analysis

AbstractA methodology has been developed to conduct probabilistic fault tree analysis during risk assessment in chemical process industries. The methodology is based on a system involving (a) development of fault tree, (b) determination of minimum cutsets or shortest pathways leading from initiating events (malfunctioning) to the top event (the major accident), (c) probability analysis, and (d) working out improvement index values. To this end techniques of Boolean algebra, structure moduling, analytical method of cutsets finding (top‐to‐bottom algorithm), Monte‐Carlo simulation, optimization technique and fuzzy probability set have been used.We named the methodology Analytical ‐Simulation Methodology (ASM) and we developed a software package PROFAT (PRObabilistic fault tree analysis) to facilitate the use of the methodology in a rapid and eflective, yet user‐friendly manner. PROFAT enables the user to find out, in an industry, (i) initiating events which may eventually lead to a major accideizt, (ii) shortest routes (minimum cutsets) a series of initiating events may take place while aiding each other in causing the accideizt. (iii) the probabilities of occurrence of such initintirig events, (iv) relative contributiom of each of the initiating events and, finally, (v) identfiing initiating events with the greatest potential to cause the top event (major accident) so that accident prevention strategies aud emergency preparedness plans can be focused on them.The noteworthy attributes of the system are: resilience towards lack of precision in the basic data, swift processing with moderate requirements of computation cupacity (sophistication of computers needed), ease of use, and direct1y utiliz‐able output. The applicability of PROFAT has been denionstrated with a case study of a sulfolane manufacturing unit.

Fault tree developed by an object-based method improves requirements specification for safety-related systems

Abstract Fault tree analysis is frequently used to improve system reliability and safety. To be suitable for analysis of software in computerised safety-related systems, it has to be modified accordingly. This paper presents a new application: the fault trees developed by an object-based method. The object-based method integrates structural and behavioural models of a system. The developed fault tree includes information on structure and the failure behaviours of classes of the system. Away from traditional use of the fault tree, which for traditional systems emphasises qualitative and quantitative results, the result of the new application emphasises the process of fault tree development and its qualitative results. Such fault tree application reduces the probability of failures in the requirements specification phase within the software life cycle, which increases the reliability of its product; however, it does not confirm this in a quantitative manner.

A task analysis-linked approach for integrating the human factor in reliability assessments of nuclear power plants

Abstract This paper describes an emerging Task Analysis-Linked Evaluation Technique (TALENT) for assessing the contributions of human error to nuclear power plant systems unreliability and risk. Techniques such as TALENT are emerging as a recognition that human error is a primary contributor to plant safety, however, it has been a peripheral consideration to date in plant reliability evaluations. TALENT also recognizes that involvement of persons with behavioral science expertise is required to support plant reliability and risk analyses. A number of state-of-knowledge human reliability analysis tools are also discussed which support the TALENT process. The core of TALENT is comprised of task, timeline and interface analysis data which provide the technology base for event and fault tree development, serve as criteria for selecting and evaluating performance shaping factors, and which provide a basis for auditing TALENT results. Finally, programs and case studies used to refine the TALENT process are described along with future research needs in the area.

CAFTA+: a comprehensive fault tree development work station : Jim Koren, John Gaertner, Jeff Riley and Blake Putney. Proc. a. Reliab. Maintainab. Synp., 6 (1986)

CAFTA+: a comprehensive fault tree development work station : Jim Koren, John Gaertner, Jeff Riley and Blake Putney. Proc. a. Reliab. Maintainab. Synp., 6 (1986)

Development of fault tree for reliability studies of a data-processing system

In this paper a systematic approach is developed for generating the fault-tree logic, which is the basic requirement in any reliability studies of large complex systems using Monte Carlo simulation or deterministic approaches. The entire network is decomposed into sub-networks, each sub-network involving several loops, and it becomes quite easy to determine failure logic for these loops and thus for the subnetworks. Failure of such subnetworks between the source and the sink node leads to a major system failure and therefore this successive development results in a fault tree for the whole network.These loops can be automatically generated. The failure event for each node in such an approach can also be accounted for. The advantage of the present methodology is that the fault-tree logic is automatically developed, which can be directly used as a sub-programme on a computer for various reliability studies of the system.