The increase in the requirements on the reliability of units makes it
necessary to analyze the relationship between mathematicalmeth- ods of
calculating reliability and the physical nature of fail- ures. The
difficulty of such an analysis is obvious. On the one hand, in making a
representation of the physical picture of a phe- nomenon, one can make
an error in the direction of excessive sim- plification. On the other
hand, in the mathematical treatment of the physical scheme, it may be
necessary to use extremely complex and fine analytical methods, and
their simplified exposition bor- ders on vulgarization. Without the aid
of a large number of specialists working in the field of analysis and
calculation of systems reliability, an ex- posi tion of models of
failures and their mathematical treatment would be unobtainable. The
authors take this opportunity to express their gratitude to Academicians
N. G. B r u y vic e h and Y u. V. Lin n i k conversations with whom
clarified a number of problems treated, to active member of the Academy
of Sciences of the UkrSSR B. V.