On the terminology of dependability

Aim. Currently, there is a fully-fledged system of Russian dependability standards, the GOST R 27.ххх series. However, due to the suspension of the terminology standard (GOST R 27.002-2009) this system is now incomplete. In this situation, a compromise solution can be found with dual designation in the current dependability standard in Russia. The aim of the paper is to define the proposals for improved basic terminology in dependability. Methods. The paper uses methods of system analysis in respect to dependability terminology. The last decade was marked by active discussions regarding dependability terminology. Not only particular definitions, but the definition of the term “dependability” itself are addressed. The dependability terminology in the Russian Federation is currently represented in two standards: the Russian GOST R 27.002-2009 (suspended indefinitely) and the interstate GOST 27.002-2015. This paper continues the discussion regarding a limited set of concepts and terms that interest the author most. Such concepts as item, entity, failure, property, ability, calculation, estimation, prediction, requirements for dependability are examined. It is noted that the concept of technical entity is based on the product, the study object as a finished result of some technical activity, i.e. to make and at the same time provide the product with the ability to perform certain functions. It is shown that a product’s properties characterize its abilities, therefore, while identifying, the focus should be on the ability of a product provided with properties (features) required for the performance of certain functions. The features (properties) themselves are primary only for the purpose of identification of the entity’s required ability and are secondary for the purpose of dependability identification. It is demonstrated that there is no need to substitute the concepts of “calculation” and “estimation”. The correctness of the definition of “prediction” in the Russian standard GOST R 27.002-2009, i.e. a computational process aimed at predicting the values of quantitative characteristics, is noted. Conclusions. Based on the terminological analysis performed in the paper, the following proposals were developed. Dependability terminology should be complemented with the definition of entity. An entity should be understood as a functional unit provided with abilities defined by the required properties. A failure should be understood as an event consisting in the disruption of the product’s up state. The concept of item should be interpreted as in GOST R 27.001-2009: an item (entity, system) that is considered individually in terms of dependability, that consists of hardware and software or their combinations. The terms of dependability, reliability, durability, etc. should be defined as the identified ability of the product to perform the required function in the given circumstances. The term “requirements for dependability” should be specified in the dependability standards. The term “dependability estimation” should not be introduced in the interstate standard GOST 27.002-2015.

item, entity, failure, property, ability, calculation, estimation, prediction, requirements for dependability

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