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Risk-informed maintenance for non-coherent systemsTao, Ye 01 December 2010 (has links)
Probabilistic Safety Assessment (PSA) is a systematic and comprehensive methodology to evaluate risks associated with a complex engineered technological entity. The information provided by PSA has been increasingly implemented for regulatory purposes but rarely used in providing information for operation and maintenance activities. As one of the key parts in PSA, Fault Tree Analysis (FTA) attempts to model and analyze failure processes of engineering and biological systems. The fault trees are composed of logic diagrams that display the state of the system and are constructed using graphical design techniques.
Risk Importance Measures (RIMs) are information that can be obtained from both qualitative and quantitative aspects of FTA. Components within a system can be ranked with respect to each specific criterion defined by each RIM. Through a RIM, a ranking of the components or basic events can be obtained and provide valuable information for risk-informed decision making. Various RIMs have been applied in various applications. In order to provide a thorough understanding of RIMs and interpret the results, they are categorized with respect to risk significance (RS) and safety significance (SS) in this thesis. This has also tied them into different maintenance activities. When RIMs are used for maintenance purposes, it is called risk-informed maintenance.
On the other hand, the majority of work produced on the FTA method has been concentrated on failure logic diagrams restricted to the direct or implied use of AND and OR operators. Such systems are considered as coherent systems. However, the NOT logic can also contribute to the information produced by PSA. The importance analysis of non-coherent systems is rather limited, even though the field has received more and more attention over the years. The non-coherent systems introduce difficulties in both qualitative and quantitative assessment of the fault tree compared with the coherent systems.
In this thesis, a set of RIMs is analyzed and investigated. The 8 commonly used RIMs (Birnbaum‘s Measure, Criticality Importance Factor, Fussell-Vesely Measure, Improvement Potential, Conditional Probability, Risk Achievement, Risk Achievement Worth, and Risk Reduction Worth) are extended to non-coherent forms. Both coherent and non-coherent forms are classified into different categories in order to assist different types of maintenance activities. The real systems such as the Steam Generator Level Control System in CANDU Nuclear Power Plant (NPP), a Gas Detection System, and the Automatic Power Control System of the experimental nuclear reactor are presented to demonstrate the application of the results as case studies. / UOIT
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Development of a computer-aided fault tree synthesis methodology for quantitative risk analysis in the chemical process industryWang, Yanjun 17 February 2005 (has links)
There has been growing public concern regarding the threat to people and
environment from industrial activities, thus more rigorous regulations. The investigation
of almost all the major accidents shows that we could have avoided those tragedies with
effective risk analysis and safety management programs. High-quality risk analysis is
absolutely necessary for sustainable development.
As a powerful and systematic tool, fault tree analysis (FTA) has been adapted to
the particular need of chemical process quantitative risk analysis (CPQRA) and found
great applications. However, the application of FTA in the chemical process industry
(CPI) is limited. One major barrier is the manual synthesis of fault trees. It requires a
thorough understanding of the process and is vulnerable to individual subjectivity. The
quality of FTA can be highly subjective and variable.
The availability of a computer-based FTA methodology will greatly benefit the
CPI. The primary objective of this research is to develop a computer-aided fault tree
synthesis methodology for CPQRA. The central idea is to capture the cause-and-effect
logic around each item of equipment directly into mini fault trees. Special fault tree
models have been developed to manage special features. Fault trees created by this
method are expected to be concise. A prototype computer program is provided to
illustrate the methodology. Ideally, FTA can be standardized through a computer
package that reads information contained in process block diagrams and provides
automatic aids to assist engineers in generating and analyzing fault trees.
Another important issue with regard to QRA is the large uncertainty associated
with available failure rate data. In the CPI, the ranges of failure rates observed could be
quite wide. Traditional reliability studies using point values of failure rates may result in
misleading conclusions. This dissertation discusses the uncertainty with failure rate data
and proposes a procedure to deal with data uncertainty in determining safety integrity
level (SIL) for a safety instrumented system (SIS). Efforts must be carried out to obtain
more accurate values of those data that might actually impact the estimation of SIL. This
procedure guides process hazard analysts toward a more accurate SIL estimation and
avoids misleading results due to data uncertainty.
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Variable Retention Harvesting: Mortality of Residual Trees and Natural Regeneration of White SpruceSolarik, Kevin Unknown Date
No description available.
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Variable Retention Harvesting: Mortality of Residual Trees and Natural Regeneration of White SpruceSolarik, Kevin 11 1900 (has links)
In this thesis I examined the impacts of variable retention harvesting on residual tree mortality and natural regeneration of white spruce [Picea glauca (Moench (Voss)] in northern Alberta. The VR was done in four overstory canopy compositions (ranging from deciduous dominated to conifer dominated) and at six rates of canopy retention (2%, 10%, 20%, 50%, 75% and 100%). After 10 years there was 32.9 % mortality of aspen (Populus tremuloides Michx.) and 16.9 % mortality of spruce in the VR cuts. Mortality of individual trees was greater with low density of trees, in the conifer stands and for trees with short live crowns, which are large and trees near machine corridors. Natural regeneration of spruce was greatest with higher availability of seed trees (>30 ha-1) and on machine corridors, where stocking reached 74%. By contrast, stocking was 14% on retention strips, when seed tree density was 11 seed trees ha-1. / Forest Biology and Management
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Analise da confiabilidade do sistema de suprimento de energia eletrica de emergencia de um reator nuclear de pequeno porteBONFIETTI, GERSON 09 October 2014 (has links)
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09246.pdf: 5265828 bytes, checksum: 4d1524b4005b3c1696584a11c7c97252 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Calculo das probabilidades de falha de suprimento de energia eletrica dos barramentos de classe IE da usina de Angra 1BORBA, P.R. 09 October 2014 (has links)
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Frequencia de danos no nucleo por blecaute em reator nuclear de concepcao avancadaCARVALHO, LUIZ S. 09 October 2014 (has links)
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Sistemas colaborativos de apoio à decisão: uma proposta de combinação de metodologias para a geração de alternativas estratégicas / Collaborative decision support systems: a proposal for combining methodologies in the generation of strategic alternativesMASSUCHETTO, VINICIUS A. 03 February 2016 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-02-03T11:55:07Z
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Analise da confiabilidade do sistema de suprimento de energia eletrica de emergencia de um reator nuclear de pequeno porteBONFIETTI, GERSON 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:48:42Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:03Z (GMT). No. of bitstreams: 1
09246.pdf: 5265828 bytes, checksum: 4d1524b4005b3c1696584a11c7c97252 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Calculo das probabilidades de falha de suprimento de energia eletrica dos barramentos de classe IE da usina de Angra 1BORBA, P.R. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:50:31Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:58Z (GMT). No. of bitstreams: 1
00048.pdf: 1060879 bytes, checksum: fa889f74fac825b31f349ea5fafec184 (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP
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