| 1. |
- Garmabaki, Amir Soleimani, et al.
(författare)
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Fleet-level reliability estimation of repairable units
- 2015
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Ingår i: Safety and Reliability. - London : CRC Press. - 9781138026810 ; , s. 1977-1982
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Konferensbidrag (refereegranskat)abstract
- This paper investigates reliability analysis of a repairable unit at fleet level. In fleet, multiple similar systems are running in different operating environments. In fact, due to the highly censored data as well as high variations in failure rate within the fleet, merging the datasets becomes a challenge. The non-parametric analysis is used to capture the failure trend of repairable units at fleet level. Consequently, fleet data have been aggregated and the actual number of failure has been compared with the expected total number of failures. In addition, parametric models are used to model the reliability trend obtained through a non-parametric approach to identify the reliability parameters at fleet level. Real data are used to demonstrate the applicability and validity of the proposed method. Results shows the accuracy of log-linear process is reasonably acceptable.
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| 2. |
- Hassel, H., et al.
(författare)
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Developing a framework for characterising cascading failures in past events to inform emergency response decisions
- 2015
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Ingår i: Safety and Reliability : Methodology and Applications - Proceedings of the European Safety and Reliability Conference, ESREL 2014 - Methodology and Applications - Proceedings of the European Safety and Reliability Conference, ESREL 2014. - : CRC Press. - 9781138026810 - 9781315736976 ; , s. 33-42
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Konferensbidrag (refereegranskat)abstract
- Increasing interdependencies between critical infrastructures have made these systems more effective, but also more susceptible to cascading failures. In order to reduce the likelihood and consequences of cascading failures, it is essential to develop tools that support incident commander decisions so that an initial failure does not spread to other infrastructures. Here, a framework for generating knowledge from previous events that can feed in to such a tool is outlined. Design science is used to this end which provides a transparent and systematic approach. Moreover, the paper presents an analysis of existing empirical approaches focusing on identifying methodological aspects that can influence the framework. Although further work is needed, the work presented in this paper shows a promising first step to accomplish such a framework.
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| 3. |
- Hoseinie, Hadi, et al.
(författare)
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Maintenance planning for drum shearer machine based on its reliability characteristics and economical sensitivity analysis
- 2015
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Ingår i: Safety and Reliability. - London : CRC Press. - 9781138026810 ; , s. 1257-1262
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Konferensbidrag (refereegranskat)abstract
- Cutting arms are the main productive units of coal shearer machine that contact directly with coal seam. More importantly, the cutting arms operate under a high stress environment. In this paper, in order to suggest an optimum maintenance plan for the subsystem of shearer machine, firstly, we conducted a failure and reliability analysis using the data acquired from the Parvadeh coal mine Iran over the last two years. In doing so, we applied estimated distribution functions and calculated cost parameters to identify the cost-based optimum preventive maintenance interval. The analysis shows that the Power Law Process model provides a good fit to the failure data. Accordingly, the preventive maintenance operation can improve the reliability of the system by 53.5%. Furthermore, we conducted a sensitivity analysis of the studied machine and identified that if we consider the variation of the world price of the raw coal then the maintenance plan is sensitive to the price, however the effects of this change on reliability improvement is almost zero
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| 4. |
- Kumar, Ranjan, et al.
(författare)
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A PSA Level-1 method with repairable components : An application to ASTRID Decay Heat Removal systems
- 2015
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Ingår i: Safety and Reliability. - : CRC Press. - 9781138026810 ; , s. 1611-1617
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Konferensbidrag (refereegranskat)abstract
- Technological advancements in area of sensor-based online maintenance systems have made the possibility of repairing some failed safety support systems of Nuclear Power Plants (NPP) such as electrical supply, I&C systems, ventilation systems. However, the possibility of repair during accident situation is yet to be included into PSA level-1. Therefore, this paper presents a scheme of PSA level-1 by implementing an integrated method of Repairable Event Tree (RET) and Repairable Fault Tree (RFT) analysis. The Core Damage Frequency (CDF) is calculated from consequence probabilities of the RET. An initiating event of Decay Heat Removal (DHR) systems of ASTRID reactor is analyzed. The proportionate CDFs estimated with repair and without repair have been compared and found that the recoveries can reduce CDF. In sum, this paper attempts to deal with the possibility of repair of some safety systems in PSA and its impacts on CDF of the NPP.
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| 5. |
- Landegren, Finn, et al.
(författare)
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Comparing Societal Consequence Measures of Outages in Electrical Distribution Systems
- 2014
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Ingår i: Safety and Reliability : Methodology and Applications - Proceedings of the European Safety and Reliability Conference, ESREL 2014 - Methodology and Applications - Proceedings of the European Safety and Reliability Conference, ESREL 2014. - : CRC Press. - 9781138026810 - 9780429226823 ; , s. 189-196
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Konferensbidrag (refereegranskat)abstract
- Quality of supply regulations are today in use in a large number of countries. While these regu-lations are likely to decrease the direct economical consequences from power outages it is less clear to what extent they take into account the societal criticality of consumers. In order to advance knowledge in this area, two different ways of estimating consequences of power outages are here contrasted. In recent years a system, named Styrel, has been introduced in Sweden, intended to enable prioritization of critical power customers from a societal perspective during times of power shortage. The Styrel prioritizations are here used as a proxy for the societal consequences of power outages. The second way of measuring consequences that arise makes use of the Swedish power outage regulation concerning outage compensations to customers. A case study is carried out for a real-life distribution system in Sweden, where failures of different sizes are simulated and the two consequence measures are calculated for each failure scenario. The overall result is that the present power outage regulation poorly mirrors the societal consequences as estimated by the Styrel prioritizations, leading to the conclusion that present day power outage regulation in Sweden is not satisfactorily taking some aspects of societal criticality into account.
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