Quantification of Simultaneous-AND Gates in Temporal Fault Trees

Fault Tree Analysis has been a cornerstone of safety-critical systems for many years. It has seen various extensions to enable it to analyse dynamic behaviours exhibited by modern systems with redundant components. However, none of these extended FTA approaches provide much support for modelling situations where events have to be "nearly simultaneous", i.e., where events must occur within a certain interval to cause a failure. Although one such extension, Pandora, is unique in providing a "Simultaneous-AND" gate, it does not allow such intervals to be represented. In this work, we extend the Simultaneous-AND gate to include a parameterized interval - referred to as pSAND - such that the output event occurs if the input events occur within a defined period of time. This work then derives an expression for the exact quantification of pSAND for exponentially distributed events and provides an approximation using Monte Carlo simulation which can be used for other distributions

Qualitative temporal analysis: Towards a full implementation of the Fault Tree Handbook

The Fault tree handbook has become the de facto standard for fault tree analysis (FTA), defining the notation and mathematical foundation of this widely used safety analysis technique. The Handbook recognises that classical combinatorial fault trees employing only Boolean gates cannot capture the potentially critical significance of the temporal ordering of failure events in a system. Although the Handbook proposes two dynamic gates that could remedy this, a Priority-AND and an Exclusive-OR gate, these gates were never accurately defined. This paper proposes extensions to the logical foundation of fault trees that enable use of these dynamic gates in an extended and more powerful FTA. The benefits of this approach are demonstrated on a generic triple-module standby redundant system exhibiting dynamic behaviour

FAILURE MAPPING PROCESS: AN APPLIED STUDY IN A SHIPYARD FACILITY

Faults represent non-conformities in productive activities. Therefore, approaches to their mitigation are relevant. Risk management techniques enable effective company’s strategic planning and the adoption of process controls towards failure reduction and assurance of adequate occupational health and safety. This research purported to integrate four widespread techniques, which are usually applied as stand-alone tools, to provide a robust risk management approach. A literature review about Process Mapping, Preliminary Hazard Analysis (PHA), Fault Tree Analysis (FTA), and Failure Mode and Effect Analysis (FMEA) is provided and their integration feasibility is analyzed, followed by an application study in a shipyard located in Rio de Janeiro state, Brazil

Analysis of time-sequential failure logic

東京商船大学博士学位論文 平成11年度(1999) 海洋情報システム工学指導教員: 佐藤吉信全文公表年月日: 2011-11-22東京商船大学199

Statistical modeling and reliability analysis for multi-component systems with dependent failures

Reliability analysis of systems based on component reliability models has drawn the great interest of many researchers so far, as one of the fundamental aspects of reliability assessment issues. In particular, reliability analysis considering dependent failure occurrences of system components is important because the components may fail mutually due to sharing workloads such as heat, tasks and so on. In such a situation, we are liable to incorrectly estimate the reliability of the system unless we consider the possibility of the dependent failure occurrence phenomena. Thus, there are many publications about this topic in the literature. Most of the existing studies deal with the dependent failure between any two components in a multi-component system since its mathematical formulation is comparatively easy. However, the dependent failure may occur among two or more components in actual cases.In this thesis, we aim at developing reliability analysis techniques when several components of a system break down dependently. First, we newly formulate a reliability model of systems with the dependent failure by using a multivariate Farlie-Gumbel-Morgenstern (FGM) copula. Based on the model, we investigate the effect of the dependent failure occurrence on the system\u27s reliability. Secondly, we deal with the parameter estimation for the model in order to evaluate the dependence among the components by using their failure times. To do so, we propose a useful estimation algorithm for the multivariate FGM copula. In addition, we theoretically reveal the asymptotic normality of the proposed estimators and numerically investigate the estimation accuracy. Finally, we present a new method for the detection of the dependent failure occurrence in an n-component parallel system. These results are helpful to both quantitative and qualitative reliability assessment of the system under the possibility of the dependent failure occurrences. Also, our estimation method is especially applicable not only the reliability analysis but also other research fields.博士(工学)法政大学 (Hosei University

状態-作用生起順序に着目したハザードの同定・分析及び抑制策導出手法の研究

国立大学法人長岡技術科学大

Utilizaçãoda metodologia "RAMS" na análise de barreiras de segurança de instalações industriais de risco elevado

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 201