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RT&A 2017, # 1(44) Vol.12


 

V. Rykov, A. Bochkov, E. Gnedenko

Editorial 

For the preceding year in the life of Gnedenko Forum and our journal there were essential changes. The President of the Forum came off duty and the members of the Editorial Board of the journal were considerably renewed. We hope that all of us together not only will keep spirit and the atmosphere of our journal, but also, we will manage to give to the business begun by Igor Ushakov, a new impulse.

 

M. Yastrebenetsky, A. Klevtsov, Y. Rozen, S. Trubchaninov

 

Fukushima Lessons for Safety of Critical Control Systems 

The accident at Japan nuclear power plant (NPP) “Fukushima-Daiichi” has influenced not only to future development of the nuclear energetics as whole and different NPP systems (including, of course, their control systems). However, the lessons of this accident are important for safety of critical control systems in different branches of industry. Some propositions for their safety assurance followed from nuclear post-Fukushima experience are discussed below.

 

I. Shubinsky, I. Rozenberg, L. Papic

Adaptive Fault Tolerance in Real-Time Information Systems 

Real-time information systems (IS) control mission-critical processes. Violation of functioning in these systems may lead to dangerous errors in control and to intolerable risks. The general disadvantage of traditional ways of IS reliability assurance is an autonomous implementation of fault tolerance mechanisms, as well as breaks of calculation which is unacceptable for real-time systems. All known ways to assure IS reliability are based on the application of large volumes of artificial structure and information redundancy. The technology of adaptive fault tolerance proposed in this article consists in the active use of natural time and structure redundancy, as well as in the active (and automatic) reassignment of available computer power not only for operational processing of information, but also for implementation of observability of the system under the conditions of limited control means. The technology of adaptive fault tolerance in information systems when solving real tasks in limited time conditions provides for a timely automatic detection and handling of failures and glitches by means of operational localization of faulty computation modules and by subsequent automatic rearrangement of the system with removal of faulty modules from the process of functioning.

 

V. Sklyar

 

Application of Reliability Theory to Functional Safety of Computer Control Systems  

Taxonomy for Dependability and Security has been updated to reflect all used attributes as well to refine orthogonality relations between attributes. Functional Safety is a part of Reliability that has dealt with Safety Functions and related dangerous failures. From this point of view, all the Reliability Theory methods, models and indicators may be applied for the Functional Safety domain without any essential change. The three main types of architecture of modern safety critical computer control systems are considered (Embedded Systems, Industrial Control Systems, and Internet of Things). Application of Reliability and Safety indicators to Industrial Control Systems of Nuclear Power Plants is given. Internet of Things has just started to be applied to safety critical systems during the last years. Research and Development program is proposed to the study of Reliability and Functional Safety.

 

À. Antonov, V. Chepurko

Mathematical Model for Calculating Reliability Characteristics NPP Equipment Under Honhomogeneous Flows Failure 

Describes the different mathematical models of nonhomogeneous in time event streams. A review of the literature on the subject of the study. The basic premise models of nonhomogeneous Poisson processes, gamma processes, geometric renewal process, the trend renewal process, the processes Kijima-Sumita. Defines the main features of the model normalizing of the flow function to calculate the required parameters of reliability. A special case of this model is an nonhomogeneous Poisson process. This model will form the basis of calculation methods of NPP equipment reliability indicators change over time and the conditions of their condition. The paper describes a method for estimating the parameters of NPP equipment reliability, which allows to take into account heterogeneity failure flow. It noted the specificity of the incoming statistical data on failures. Noted the specificity of the incoming statistical data on failures. The application of the model normalizing the flow function to calculate the required parameters of reliability. An example of a practical analysis of the failures of some elements of the reactor protection management system (PMS) NPP Bilibino.

 

G. Johnson, A. Duchac

The Development of the New Idea Safety Guide for Design of Instrumentation and Control Systems for Nuclear Power Plants

The International Atomic Energy Agency (IAEA) is a United Nations organization that was formed to "accelerate and enlarge the contribution of nuclear energy to peace, health and prosperity throughout the world." The IAEA prepares Safety Standards in accordance with the IAEA. These Standards are not binding on Member States, but may be adopted by them. The Safety Standards are, however, binding for the IAEA's own activities (safety reviews, technical cooperation missions, training activities), on the IAEA, and on Member States. IAEA Safety Standards are organized into three levels: Safety Fundamentals, Safety Requirements, and Safety Guides. It is necessary to take the measures recommended. Currently nearly 120 safety guides are in effect. The article gives an extensive review of existing documents.

 

V. Koroliuk, D. Koroliouk

Heuristic Principles of Phase Merging in Reliability Analysis 

B.V. Gnedenko was the founder of reliability analysis for stochastic systems. His works [1]-[2] have inspirited, in reliability theory, the development of analytical methods of phase state merging principles for Markov and semi-Markov processes.

 

I. Gertsbakh, Y. Shpungin

System Reliability for Shock and Lottery Models 

In this note we consider how system signatures (D-spectra) can be used in computing system reliability for "shock" and "lottery" models of system reliability.

 

M. Manoharan , Vidhya G Nair

Evaluation of System Performance Measures of Multi State Degraded System with Minimal Repair 

There is a recent surge of interest in multi state systems mainly due to their wide applications in engineering. Multi state degraded systems have been used in modeling of power generating-supply systems, communication systems and transportation systems etc. In this article we propose a new approach ie, a combination of stochastic process approach and Universal Generating Function(UGF) technique by decomposing system in to several subsystems. Analyzing models through this approach, several system performance measures are evaluated. A real data obtained from a power station modeled as a MSS which has two subsystems with many states of degradation, has been used for illustration to apply the approach presented here.

 

 

 

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