Dmitry A. Maevsky, Helen D. Maevskaya, Alexander A. Leonov

The article describes the main provisions of the new theory of software reliability, which is not based on probability theory and the theory of non-equilibrium processes. Emerging from the operation of software systems, defects are considered as the result of the forward and reverse defect flows. Relations are developed to predict the number of identified and introduced to system defects and they are opening the possibility of modeling the reliability of software systems, taking into account the secondary defects. It is shown that the majority of existing software reliability models can be derived from the provisions of the dynamics of software systems.

A. Bochkov, I. Ushakov

The problem of optimal resources allocation for antiterrorism preventive measures is naturally based on subjective estimates made by experts in this field. Relying on expert estimates is inevitable in this case: there is no other possibility to get input data for the system survivability analysis. There is no such phenomenon like “collecting real data”, moreover, there is no “homogenous samples” for consistent statistical analysis of observations, since any case is unique and non-reproducible. Nevertheless, quantitative analysis of necessary level of protection has to be performed. First of all, we should underline that concept of “optimal solution” relates only to mathematical models. In practice unreliable (and even inconsistent) data and inevitable inaccuracy of the model (i.e. difference between a model and reality) allow us to say only about “rational solutions”. Nevertheless, in practice the problem exists and in any particular case has to be solved with or without using mathematical models. Our objective is to analyze stability of solutions of the optimal resources allocation under fuzziness of experts’ estimates.

A. Orekhova, V. Kharchenko, V. Tilinskiy

A safety assessment approach for human-machine interfaces (HMI) of Nuclear Power Plant (NPP) instrumentation and control systems (I&Cs) based on the Safety Case methodology is proposed. I&C assessment model is described taking into account human factor impact. Normative profile based on harmonization and standard requirements selection for choice of HMI safety assessment methods is developed. Ranking of major design principles of safe HMI is provided. Set of methods for comprehensive human machine interface safety assessment at life cycle stages is analyzed and adopted taking into consideration features of HMI safety attribute.

G.Tsitsiashvili

In this paper a problem to define direct and inverse sets of nodes connected with failed node is considered. This problem is solved by a calculation of connectivity matrix. To simplify initial network a problem of a minimization of its numbers of nodes and arcs is solved also. Calculation complexity of this solution is approximately cubic by a number of nodes.

O.V. Abramov, D.A.Nazarov

An approach to ensure the reliability of engineering systems at design stage is considered in this paper. This approach is associated with construction of an acceptable region inside the system parameter space. A model that describes an acceptable region constructed on the basis of multidimensional grid is offered. The methods for reducing amount of data with respect of resource limitations and particulars of data decomposition for its parallel processing are described.

G. Tsitsiashvili

In this paper a problem of asymptotic estimate for connectivity probability of non oriented connected graph with fold and low reliable arcs is solved. An algorithm of a calculation of asymptotic constants with cubic complexity by a number of nodes is constructed. This algorithm is based on Kirchhoff`s theorem for a calculation of a number of spanning trees and relative characteristics.

Yu. Paramonov, R. Chatys, J. Andersons, V. Cimanis, M. Kleinhofs

This paper is a review integrating, amending, and developing the approach applied in authors’ previous works devoted to the tensile and fatigue reliability analysis of unidirectional composite material considered as a series system the links of which are, in general case, complex parallel systems with redistribution of load after failure of some items. By processing experimental data it is shown that the models based on the Markov chains  (MCh) theory  allow (1) to describe connection of cdf of tensile strength of fibers (strands) and a composite specimen, (2) to perform nonlinear regression analysis of fatigue curve and prediction of its changes due to a change of tensile strength characteristics of the composite components, (3) to predict the fatigue life at a program loading, (4) to estimate  the cdf of the residual strength and residual life after a preliminary fatigue load.

Igori B. Spiridonov, Armen S. Stepanyants, Valentina S. Victorova

This paper summarizes the result of an effort to develop a unified approach to design-driven testability evaluation of avionic systems. These systems include both internal diagnostic equipment referred to as built-in-test (BIT) and external off-line test equipment. At the designing stage an adequate database to evaluate the quality of the BIT is the failure mode and effect analysis. In the paper various mathematical indices are suggested and constructed to quantify testability of avionic systems. The indices provide the needed flexibility for representing structural and reliability properties of the controlled system. Analytical model for evaluation BIT performance impact on the system’s reliability is discussed.

G.Tsitsiashvili

In this paper limit theorems for closed queuing networks with excess of servers are formulated and proved. First theorem is a variant of the central limit theorem and is proved using classical results of V.I. Romanovskiy for discrete Markov chains. Second theorem considers a convergence to chi square distribution. These theorems are mainly based on an assumption of servers excess in queuing nodes.

Igor Ushakov