System safety concept compared

LOPA is a semi-quantitative tool for analyzing and assessing risk. This method includes simplified methods to characterize the consequences and estimate the frequencies. Various layers of protection are added to a process, for example, to lower the frequency of the undesired consequences. The protection layers may include inherently safer concepts the basic process control system safety instrumented functions passive devices, such as dikes or blast walls active devices, such as relief valves and human intervention. This concept of layers of protection is illustrated in Figure 11-16. The combined effects of the protection layers and the consequences are then compared against some risk tolerance criteria. 

Essential medicines are those that satisfy the priority health care needs of the population. They are selected with due regard to public health relevance, evidence on efficacy and safety, and comparative cost effectiveness. Essential medicines are intended to be available within the context of functioning health systems at all times in adequate amounts, in the appropriate dosage forms, with assured quahty and adequate information, and at a price the individual and the community can afford. The implementation of the concept of essential medicines is intended to be flexible and adaptable to many different situations exactly which medicines are regarded as essential remain a national responsibility... 

ABSTRACT The draft document of the NATO allied ordnance publication (AOP) 52 gives guidance on software safety design and assessment of ammunition-related computing systems. The content of the draft is reviewed and compared with the lEC 61508 standard for functional safety of electrical/electronic/programmable electronic (E/E/PE) systems. We discuss the overall development model, the safety-lifecycle model and proposed techniques and measures. We also investigate whether the functional safety concept of lEC 61508 is incorporated in the document. 

The Department of Defense s Standard Practice for System Safety, MIL-STD-882, was originally issued in 1969. It was a seminal document at that time, and three revisions of it have been issued over the span of 31 years. This standard has had considerable influence on the development of risk assessment, risk elimination, and risk control concepts and methods. Much of the wording on risk assessments and hierarchies of control in safety standards and guidelines issued throughout the world is comparable to that in the various versions of MIL-STD-882. 

For different assumptions of concepts the results of their applications in practice have not been the same. From these reasons in next paragraphs we compare mentioned concepts, especially in engineering disciplines and judge the vahdity of their use with regard to their capabiUty to ensure human system safety, i.e. human security, existence and sustainable development. 

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