Yes / Fault tree analysis (FTA) is a powerful technique that is widely used for evaluating system safety and reliability. It can be used to assess the effects of combinations of failures on system behaviour but is unable to capture sequence dependent dynamic behaviour. A number of extensions to fault trees have been proposed to overcome this limitation. Pandora, one such extension, introduces temporal gates and temporal laws to allow dynamic analysis of temporal fault trees (TFTs). It can be easily integrated in model-based design and analysis techniques. The quantitative evaluation of failure probability in Pandora TFTs is performed using exact probabilistic data about component failures. However, exact data can often be difficult to obtain. In this paper, we propose a method that combines expert elicitation and fuzzy set theory with Pandora TFTs to enable dynamic analysis of complex systems with limited or absent exact quantitative data. This gives Pandora the ability to perform quantitative analysis under uncertainty, which increases further its potential utility in the emerging field of model-based design and dependability analysis. The method has been demonstrated by applying it to a fault tolerant fuel distribution system of a ship, and the results are compared with the results obtained by other existing techniques.

The thesis deals with project management body of knowledge with focus on a risk management. It explained the importance of risk management in software developing projects. Risk management cycle and used methodology is described. The core unit of second part is requirements analysis for risk management support system, description of the application via UML and implementation of application which was created in development environment NetBeans IDE 6.5 in Java language. Conclusion of my thesis contains a short summary and possible way of extension.

Nuclear-based hydrogen generation is a promising way to supply hydrogen for this large market in the future. This thesis focuses on one of the most promising methods, a thermochemical Cu-Cl cycle, which is currently under development by UOIT, Atomic Energy of Canada Limited (AECL) and the Argonne National Laboratory (ANL). The safety issues of the Cu-Cl cycle are addressed in this thesis. An investigation of major accident scenarios shows that potential tragedies can be avoided with effective risk analysis and safety management programs. As a powerful and systematic tool, fault tree analysis (FTA) is adapted to the particular needs of the Cu-Cl system. This thesis develops a new method that combines FTA with a reliability analysis tool, multi-state system (MSS), to improve the accuracy of FTA and also improve system reliability. / UOIT

A method able to analyze and optimize subsystems could be useful to reduce project cost, increase subsystem reliability, improve overall aircraft safety and reduce subsystem weight. The earlier the optimization of development of an aircraft in the design phase can be performed, the better the yield of the optimization becomes. This master thesis was formed in order to construct an automatic analysis method, implementing a Matlab script, evaluating devices forming aircraft subsystems using a Genetic Algorithm. In addition to aircraft subsystems, the method constructed in the work is compatible with systems of various industries with minor modifications of the script.

Modern society is unquestionably heavily reliant on supply of electricity. Hence, the power system is one of the important infrastructures for future growth. However, the power system of today was designed for a stable radial flow of electricity from large power plants to the customers and not for the type of changes it is presently being exposed to, like large scale integration of electric vehicles, wind power plants, residential photovoltaic systems etc. One aspect of power system control particular exposed to these changes is the design of power system control and protection functionality. Problems occur when the flow of electricity changes from a unidirectional radial flow to a bidirectional. Such an implication requires redesign of control and protection functionality as well as introduction of new information and communication technology (ICT). To make matters worse, the closer the interaction between the power system and the ICT systems the more complex the matter becomes from a reliability perspective. This problem is inherently cyber-physical, including everything from system software to power cables and transformers, rather than the traditional reliability concern of only focusing on power system components. The contribution of this thesis is a framework for reliability analysis, utilizing system modeling concepts that supports the industrial engineering issues that follow with the imple-mentation of modern substation automation systems. The framework is based on a Bayesian probabilistic analysis engine represented by Probabilistic Relational Models (PRMs) in com-bination with an Enterprise Architecture (EA) modeling formalism. The gradual development of the framework is demonstrated through a number of application scenarios based on substation automation system configurations. This thesis is a composite thesis consisting of seven papers. Paper 1 presents the framework combining EA, PRMs and Fault Tree Analysis (FTA). Paper 2 adds primary substation equipment as part of the framework. Paper 3 presents a mapping between modeling entities from the EA framework ArchiMate and substation automation system configuration objects from the IEC 61850 standard. Paper 4 introduces object definitions and relations in coherence with EA modeling formalism suitable for the purpose of the analysis framework. Paper 5 describes an extension of the analysis framework by adding logical operators to the probabilistic analysis engine. Paper 6 presents enhanced failure rates for software components by studying failure logs and an application of the framework to a utility substation automation system. Finally, Paper 7 describes the ability to utilize domain standards for coherent modeling of functions and their interrelations and an application of the framework utilizing software-tool support. / <p>QC 20140505</p>

Reliability and safety of complex software-intensive systems are proved to be a crucial matter since most of these systems fulfil tasks, where a failure could lead to catastrophic consequences. For example, in space systems such as satellites, a failure could result in the loss of the satellite. Therefore, a certain level of reliability and safety must be assured for such systems to trust the services they provide. Standards set this level and put requirements for the analysis and assurance of these properties using documented evidence. In particular, European Cooperation for Space Standardization (ECSS) standards for space systems require Fault Tree Analysis(FTA) for identifying the causes of system failure and consequently safety hazards, as well as fault trees as evidence for the assurance of reliability and safety. In this thesis, we present a tool supported model-based approach to generate fault tree automatically from an existing system modelling and analysis toolset. CHESS is a system and dependability modelling toolset and integrates Concerto-FLA to enable the support of failure logic analysis. We proposed a model-based transformation from Concerto-FLA to fault tree model and implemented it as an Eclipse plugin in CHESS toolset. A case study is performed in the aerospace domain; more specifically we modelled Attitude Control System (ACS) and automatically generated IEC-61025-compliant fault trees. / AMASS project

Made available in DSpace on 2014-10-09T12:27:40Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:16Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Orientador: Katia Lucchesi Cavalca / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-05T06:52:34Z (GMT). No. of bitstreams: 1 Morello_MarceloGuimaraes_M.pdf: 1601336 bytes, checksum: 655c77577c3e8d4b8a3a47267a03ffa5 (MD5) Previous issue date: 2005 / Resumo: O trabalho tem como objetivo determinar a vida útil de componentes de veículos comerciais, e obter uma árvore de falha (Failure Tree Analyis-FTA) reduzida para caixas de câmbio. Nesta redução são utilizados modelos estatísticos de confiabilidade para ajustar os parâmetros dos componentes que geram falhas, sendo complementada com uma aplicação de planejamento fatorial com dois fatores, para se identificar os componentes mais sensíveis à variação dos parâmetros nas distribuições de confiabilidade. A árvore de falhas foi construída considerando os seguintes parâmetros: vida característica (a) e parâmetro de forma (b), para distribuição de Weibull, e para as distribuições Lognormal e Normal, vida média (µ) e desvio-padrão (s) para cada componente. Considerando os componentes mais críticos com a utilização da FTA, pode-se reduzir a árvore de falhas em relação ao número de componentes, em aproximadamente em 30%, facilitando o direcionamento de melhorias em função do aumento da confiabilidade do produto, neste caso, caixas de câmbio. Esse método pode ser ampliado a outros sistemas de um veículo, permitindo a modelagem estatística do sistema, para a identificação dos principais componentes que causam ou conduzem às falhas em determinadas quilometragens / Abstract: This work has the objective of assembling a reduced fault tree for sensitivity analysis applied to gearboxes in commercial vehicles. This reduction contains the study of the most representative statistical models for reliability evaluation of all components of the system that generate failures, being complemented with an application of factorial planning with two factors to identify the most sensible components to the variation of the parameters in the reliability distributions. Thus, fault tree was constructed from the factors: characteristic life (a) and parameters form (b) to Weibull distribution and life mean (µ) and standard deviation (s) to Normal and Lognormal distribution, for each component. With these techniques, the FTA can be reduced as well as the number of components around 30%, whose contributes directly in the improvement of the product¿s reliability, in this case, gearboxes. This method can be extended to other systems of a vehicle, allowing the statistical modeling of the system that can also contribute to the identification of the main components that are the cause or lead to the failures in specific kilometers / Mestrado / Mecanica dos Solidos e Projetos / Mestre em Engenharia Mecânica

Made available in DSpace on 2014-10-09T12:27:40Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:16Z (GMT). No. of bitstreams: 0 / Este trabalho teve como objetivo o desenvolvimento de um sistema computacional (software) de gerenciamento de risco, viabilizando o diagnóstico dos riscos dos processos de radioesterilização de tecidos biológicos. O gerenciamento de risco pode ser entendido como uma gestão sistemática que tem por objetivo identificar, registrar e controlar os riscos de um processo. Para a execução do gerenciamento de risco são requisitos fundamentais: a experiência, o discernimento e o julgamento de uma equipe multidisciplinar, direcionada por meio de ferramentas de qualidade, no intuito de proporcionar padronização no processo investigativo das causas e efeitos dos riscos; dinamismo também é requisito no alcance do objetivo desejado: a redução e o controle do risco. Nesse sentido, a aplicação do gerenciamento de risco torna-se uma atividade complexa, devido à variedade de profissionais envolvidos. Por isso, o apoio de um sistema computacional é tão importante, pois, no que tange ao gerenciamento de risco, o software facilita as tarefas do responsável pelo processo de radioesterilização de tecidos biológicos, que pode, inclusive, contar com a utilização de normas e guias específicos. Essas informações de sumária importância são indexadas nos diagnósticos de riscos, o que torna possível ao responsável qualificado a execução de ações corretivas para a garantia da segurança do processo. A metodologia adotada neste trabalho foi a pesquisa-ação, segundo a qual o pesquisador desempenha um papel ativo no equacionamento dos problemas encontrados, bem como no acompanhamento e avaliação das ações desencadeadas em função dos problemas observados. O cenário dessa pesquisa-ação foi o Laboratório de Tecidos Biológicos (LTB) no Centro de Tecnologia das Radiações (CTR, IPEN/CNEN-SP, Brasil). O software foi desenvolvido em linguagem PHP e Flash/MySQL e está hospedado num servidor que o torna disponível na internet via endereço www.vcrisk.com.br, podendo, então, ser acessado de qualquer lugar pelo usuário , por meio de um login/senha previamente encaminhados por e-mail. O sistema computacional apresenta uma navegabilidade amigável, o que permite que o usuário seja guiado, passo a passo, no processo investigativo do risco até as suas medidas de redução. Tal sistema direciona o usuário a apresentar a efetividade das ações tomadas para redução do risco dentro de prazos previstos. Assim, o uso desse sistema proporciona à organização (LTB/CTR/IPEN) uma comunicação dinâmica e efetiva entre os membros da equipe multidisciplinar: a) na tomada de decisões; b) nas lições aprendidas; c) no conhecimento do novo risco e suas ações para mantê-lo controlado; e d) no gerenciamento de falhas e riscos, garantindo a realização da principal meta de um laboratório de radioesterilização de tecidos biológicos que é a excelência de qualidade do tecido radioesterilizado. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

This thesis deals with design of a suitable approach for managing the supply of spare parts for machines approaching decommissioning. The appropriate balance between outstanding risks related to equipment downtime and costs of holding spare parts is predicted by proposed systematic algorithm. Determination of key parameters affecting the whole process of spare parts inventory management and their subsequent use as a basis for Event Tree Analysis lead to finding an optimum set-up, which mitigates the overall impact of the planned reduction in spare parts storage levels. The new approach has a number of advantages including versatility of application for many types of machines, as well as a different outlook on a solution for the current issue in spare parts management.