| 1. |
- Flammini, Francesco, Senior Lecturer, 1978-, et al.
(author)
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Evaluating the Hazardous Failure Rate of majority voting computer architectures by means of Bayesian Network models
- 2007
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In: Proceedings of the European Safety and Reliability Conference 2007, ESREL 2007 - Risk, Reliability and Societal Safety. - 0415447860 - 9780415447867 ; , s. 1715-1721
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Conference paper (peer-reviewed)abstract
- Safety-critical control systems are usually based on majority voters. In order to assess the compliance of these architectures with international safety standards, the probability of the occurrence of unsafe events should be evaluated by developing and analyzing proper formal models. In this paper we demonstrate that a Bayesian Network (BN) model can be used to evaluate the Mean Time Between Hazardous Events (MTBHE) of voting architectures. The proposed modeling approach is applied to a "2 out of 2" ("2002") voter consisting of independent computing units. The results obtained from the analysis of the BN model of the "2002" voter can be easily extended to evaluate the hazardous failure rate of more complex voting architectures (e.g. Triple Modular Redundant architectures, based on a 2003 voting). Within this context, BNs have several advantages over other traditional approaches (e.g. Petri Nets or Markov Chains): the model can be directly derived from the analysis of the flow-chart describing the dynamic of hazardous failures and its evaluation is much more efficient, as BN solving algorithms are non state-based; moreover, sensitivity analyses can be automatically performed by using the available user friendly BN tools . Finally, the proposed BN model is quite general and can be easily adapted and/or extended to suit specific computing architectures and fault models. © 2007 Taylor & Francis Group.
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| 2. |
- Ahmadi, Alireza, et al.
(author)
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An overview of trends in aircraft maintenance program development : past, present, and future
- 2007
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In: Risk, Reliability and Societal Safety. - London : Taylor and Francis Group. - 9780415447867 ; , s. 2067-2076
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Conference paper (peer-reviewed)abstract
- The purpose of this paper is to describe the trends in aircraft maintenance program development during the last 50 years, including the reasons for the aircraft industry to change its view of maintenance. The major milestones and fundamental reasons for such development are also discussed and illustrated in relation to a flow diagram, which shows the logical and chronological order of the trends. Finally, the paper describes some possibilities and challenges as regards applying Information & Communication Technology (ICT) within the emerging approach of e-Maintenance in order to enhance the surveillance of aircraft maintenance program performance.
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| 3. |
- Barabady, Javad, et al.
(author)
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Implementation of production availability programmes in engineering projects
- 2007
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In: Risk, Reliability and Societal Safety. - London : Taylor and Francis Group. - 9780415447867 ; , s. 487-494
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Conference paper (peer-reviewed)abstract
- The aim of this paper is to present and discuss a methodology for implementing production availability programmes in engineering projects. The programmes are to ensure that the project goals will be met. The programme describes the production availability activities necessary to fulfil the objectives, how they will be carried out, by whom and when. The activities provide input to decisions regarding concept, design, manufacturing, construction, installation, operation and maintenance. The proposed methodology consists of three primary tasks and decisions. The three primary tasks are i) establish production availability requirements; ii) provide input to the design process and to operations; and iii) monitor production availability achievement and publish periodic report. Establishing the proposed methodology will help ensure that the project has a cohesive and cost-effective production availability programme, reflecting a production availability process and activities defined in view of the actual needs, available personnel resources, budget framework, interfaces, milestones, and access to data and general information.
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| 4. |
- John, Stoop, et al.
(author)
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Public safety investigations - a new evolutionary step in safety enhancement?
- 2007
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In: Risk, Reliability and Societal Safety. - 9780415447867 ; , s. 943-950
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Conference paper (peer-reviewed)abstract
- Over the past years, natural catastrophes have disrupted society: the tsunami in December 2004, hurricane Katrina in the Gulf of Mexico, the earthquakes in Pakistan in 2005, causing massive material destruction and human suffering. In addition, technological accidents in transport, energy and process industry undermine the public faith in risk management, while the uncontrolled spreading of diseases and viruses put high demands on medical and emergency responses and public governance decision making. The use of experiences and lessons learned from such major events is considered a valuable tool in understanding causal mechanisms and in taking appropriate measures to prevent recurrence, reduction of the consequences and restoring public faith in governance and decision making. Started in the transportation industry in the early sixties of the previous century, the phenomenon of independent public safety investigations has now been recognized as a valuable tool for safety enhancement in other industrial sectors and areas of public governance. At an international level, the EU has issued several Guidelines for their mandatory application in high-tech sectors, putting demands on the Member States to install independent governmental agencies, to harmonize concepts and investigation procedures and to feed back their findings and recommendations in EU policy making. Apart from their substantive contribution to improving knowledge about causal phenomena and accident prevention, safety investigations have been advocated as high potential tools in restoring public faith after a major event and in arbitration in societal dissensus about risk acceptability and risk perception. Safety investigations focus on enhancing the systems safety performance in contrast to accident investigations, which have their focus on preventing recurrence of accidents and incidents. Conducting safety investigations have been characterized as a Citizens' Right and Society's Duty. Such a recognition however, also sets a series of challenges for a wider application of this investigation tool outside its original technical domain, expanding the concept to all phases of the accident sequence, before, during and after the event, and to higher levels of the socio-technical systems in which the events are embedded and risk debates require expertise in supporting risk ion making. This contribution is primarily based on observations of trends and patterns as they emerge in society, and by the lack of scientific literature, assessed by expert judgment. It describes and analyses several trends and types of investigations that have developed over the past decade, focusing on their strengths and weaknesses, dilemmas, potential for prevention and ability to change systems safety characteristics. It identifies critical areas of attention for further development focusing on substantive issues as well as specific sectorial and national constraints in their implementation.
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