Safety-Critical Computing: Hazards, Practices, Standards, and Regulation

Jacky, Jonathan

doi:10.1016/b978-0-12-415040-9.50146-9

Cited by 5 publications

(1 citation statement)

References 37 publications

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“…When the operator switched from X-ray to electron mode, the machine was supposed to withdraw the target and set the beam back to low intensity. This would be the case, and had indeed been the case until then, unless the whole sequence of operations took less than 8 seconds (Jacky, 1996).…”

Section: The Role Of Users In Learning From Accidentsmentioning

confidence: 94%

Moral Hazard and the Role of Users in Learning from Accidents1

Fauchart¹

2006

J Contingencies & Crisis Man

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Most technological accidents studied in the literature consist of a single event occurring in a single location (Challenger, Chernobyl, Ariane 5, Bhopal, etc.). However, a significant number of accidents comprise a series of incidents taking place in multiple and unconnected locations. This may happen whenever a given technology is used by multiple decentralized users -as is the case for medical devices or diving equipment, for instance. In this paper, we argue that such a structural characteristic raises specific problems and issues in terms of learning from accidents. We focus on a specific issue and problem: information asymmetries between the users and the manufacturer in favor of the manufacturer and the risk of ''moral hazard'' that they can induce. Using second hand information on a well known case (Therac-25), we show how the manufacturer behaved opportunistically when it came to learn from a series of decentralized incidents and we argue that this opportunism was made possible by information asymmetries. Following predictions from the principal-agent theory, we then argue that for users to monitor manufacturers' behavior in a sense favorable to the taking place of learning from accident, it is necessary to ensure communication among users of risky technologies. Besides reducing information asymmetries conducive to moral hazard this would moreover improve risk prevention. Yet, as communication among decentralized users is unlikely to arise spontaneously in most cases, we argue that this makes the case for public intervention in the form of publicly sponsored user groups.n Laboratoire d'é conomé trie, Conservatoire national des arts et mé tiers

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Section: The Role Of Users In Learning From Accidentsmentioning

confidence: 94%

Moral Hazard and the Role of Users in Learning from Accidents1

Fauchart¹

2006

J Contingencies & Crisis Man

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Intelligent technologies for nuclear power systems: heuristic and neural tools

Nissan

1998

Expert Systems with Applications

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Experiences with specification and verification in LOTOS: a report on two case studies

Kirkwood

Thomas

Proceedings of 1995 IEEE Workshop on Industrial-Strength Formal Specification Techniques

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We consider the problems of verifying properties of LOTOS speci cations with speci c reference t o t w o case studies, one of which was proposed b y a n i n d u strial collaborator. The case studies present quite different veri cation requirements and we study a range of veri cation and validation techniques, based o n various behavioural congruences and preorders, which may be applied, also using some mechanised t o ol support. We consider the implications of the (formal) proofs which succeed or fail with respect to our desired properties, and draw some conclusions about the verication process. what we can conclude about the state of the art in LOTOS veri cation. In this paper we g i v e a n o verview of some of the work we h a ve carried out, including the techniques and tools used, and two kinds of case studies considered. We describe our experiences with two particular case studies in some detail: a communications protocol and a control device for a dual mode radiotherapy m a c hine. The former case study originates from a major U.K. defence contractor and the latter is an abstraction of a real machine. While some aspects of these two particular studies have been reported elsewhere, e.g. in 13] and 24], we use these two studies here to illustrate what we h a ve learned about various aspects of the veri cation issues given above, as well as reporting on further work on the studies. LOTOSThe reader is referred to the LOTOS standard 10] and 1] for an introduction to LOTOS. LOTOS consists of two parts: so-called Basic LOTOS, for describing interaction and ow o f c o n trol, and ACT ONE, for describing equationally speci ed abstract data types. Basic LOTOS is very similar to CCS 21], drawing some aspects, particularly multi-way s y n c hronisation, from CSP 9].The semantics of LOTOS speci cations are given by structured labelled transition systems (de ned by inference rules). Various relations based on observable behaviour may be de ned over these systems we have found the most useful relations for veri cation purposes are weak bisimulation congruence and the testing relation cred. The full de nitions of these relations may be found in 10].Brie y, t wo processes are weak bisimulation congruent if they have the same observable behaviour in all contexts, ignoring occurrences of the internal action, and two processes are related via the cred preorder if, in all contexts, whenever one process passes a test, the other process does too. We c hoose these relations as the system under examination will probably have t o interact with other systems, therefore it is important that it behaves in the same way in all contexts.

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Safety-Critical Computing: Hazards, Practices, Standards, and Regulation

Cited by 5 publications

References 37 publications

Moral Hazard and the Role of Users in Learning from Accidents1

Moral Hazard and the Role of Users in Learning from Accidents1

Intelligent technologies for nuclear power systems: heuristic and neural tools

Experiences with specification and verification in LOTOS: a report on two case studies

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