• Jens Braband, Rüdiger von Hövel and Hendrik Schäbe,
  PROBABILITY OF FAILURE ON DEMAND – THE WHY AND THE HOW

In the paper, we will study the PFD and its connection with the probability of failure per hour  and failure rates of equipment using very simple models. We describe the philosophies that are standing behind the PFD and the THR. A comparison shows, how the philosophies are connected and which connections between PFH and PFD are implied. Depending on additional parameters, there can be deviations between safety integrity levels that are derived on the basis of the PFD and the PFH. Problems are discussed, which can arise when working with the PFD. We describe, how PFD and PFH in IEC 61508 are connected with the THR defined in the standard EN 50129.We discuss arguments that show, why care is needed when using the PFD. Moreover, we present a reasoning, why a probability of failure on demand (PFD) might be misleading.
Keywords: Probability of failure on demand, rate of dangerous failures, safety integrity level.

Structural reliability. The theory and practice

• V. Gapanovich, E. Rozenberg, I. Shubinsky
  MODEL OF RELIABILITY OF A RESTORED TECHNICAL DEVICE IN VIEW
  OF IDLE TIMES IN WORK

Indices of non-failure operation and availability of technique, stated in the domestic standard of GOST 27.002-89 and international standard IEC 62278:2002 (RAMS) are compared in the article. The large similarity of indices is marked that testifies to fundamentality of positions of the specified domestic standard. At the same time, the divergence in interpretation of such an important complex parameter as factor of availability takes place. On an example of reliability model of the controlled and restored device with the latent failures it is shown by authors, that the modern standard on RAMS more really considers practical conditions for insuring availability of technical equipment than that does the specified domestic standard and it provides more correct approach to the definition of formula expression of availability factor of technical equipment.  
Keywords: non-failure operation, availability, latent failure, non-ideal control, probability of correct detection, probability of failure missing, factors of availability and unavailability, average time between failures (ATBF), average time between refusals, average time before restoration, reliability model.

• Nosov M.V.
  LIMIT EVALUATION SYSTEM RELIABILITY NETWORKED
  (Part 1)

The method of justification for limiting assessment (software) reliability of systems with network structure, which uses some properties of the Shannon expansion formula. Formulated and proved the existence of conditions on, and given the structure of evaluation of graphs and their corresponding formal expressions for the calculation of the probability of connectivity (probably disconnected) bipolar random graphs.
Key words and accepted abbreviations:
SNS - a system with a network structure, SC - the system of communication, LA - limiting the assessment; PC - the probability of connectedness, PD - probability disconnected; BRG - bipolar random graph, SC - a simple circuit; SI - a simple incision, RF - readiness factor; UP - upper bound, BA - bottom assessment; EV - the exact value; EEP - evaluation of Esar-Proshan; ELU - evaluation Litvak-Ushakov.

• Petrov G.A.,  Rezinovsky A.Y.
  PROPOSALS FOR OPTIMIZATION METHOD CORRECTIONS OF THE STOCKS IN SPARE PARTS, TOOLS AND ACCESSORY COMPLEXES.

The widespread design method of the projected spare parts, tools and accessories complex is considered based on the expense optimization for the stocks in it (that is on the assumption of simultaneous meeting requirement and the complex sufficiency indexes and its costs (mass or dimensions)).
At that the zero reserve unsubstantial rather often recommended by this method is underlined.
It is proposed to replace the reserve expense optimization for the quantity optimization of spares (from one for each type) as a matter of long – term practice of the spare parts, tools and accessories complex estimates for the multiple products and tested experienced models.
Keywords: spare parts, tools and accessories; reserve (stock); spare part; spare parts, tools and accessories complex; reserve sufficiency indexes; initial reserve level; spare part expense in whole; primary and auxiliary reserves; reserve supplement strategy.

• Grishunina J.B.    
  OPTIMAL STRATEGY OF  REPAIR IN SEMI-MARKOV MODEL OF     TECHNICAL MAINTENANCE.

A technical system with two possible types of maintenance is considered. The first type of maintenance is an emergency repair, by the termination of which tear and wear of the system doesn't change. The second type is the major repair by a termination of which the system is totally updated. The decision about the type of the repair is taken according to the distribution of the solution set that depends on the tear and wear of the system at the moment of the failure. We formulate and solve the problem of optimal choice of the repair type with the maximization target of functional average specific income. It was proved that the optimal control is singular. Moreover, in the case of an increasing failure rate (IFR) lifetime  distribution the optimal control is singular and has a form of a threshold with no more than one switching point.
Keywords: controlled semi-Markov process, homogeneous Markov randomized strategy of control, additive functional of income, Pontryagin’s maximum principle, increasing failure rate (IFR) distribution, optimal control.

• Volodarsky V.A.
  THE REPAIRABLE SYSTEM MEAN TIME BETWEEN FAILURES

The research result of the repair frequency influence and reliability restoration intensity on the value of technical systems mean time between failures is applied.
Keywords: reliability, mean time between failures, restoration intensity, repair.

• Pavlov Nikolay
  SOLDER JOINT RELIABILITY IN SPECIAL-PURPOSE EQUIPMENT

Manufacture of special (military, space, medical and of some other responsible branches) technicians is one of priority problems for any state. Except functional characteristics of one of the main one reliability of a product in operation is. Considering, what all modern workings out have “an electronic stuffing” It is necessary to consider as special reliability section is reliability soldering connections and reliability of components.
Keywords: Solder joint reliability, special-purpose equipment, lead-free technology, thermal fatigue stresses

• Markin A.V., Polesskey S.N., Zhadnov V.V.  
  METHODS OF THE ESTIMATION OF MECHANICS ELEMENTS RELIABILITY AND ELECTROMECHANICS OF ELECTRONIC MEANS AT EARLY DESIGN STAGES

The classical apparatus of reliability theory of complex systems which is based on hypothesis about constancy failure rate of elements, is widely used in engineering practice for the analysis of reliability electronic means. At carrying out of these jobs value failure rate of mechanics and electromechanics elements are defined in the directory «Надежность ЭРИ» or aren't considered at all. If to take into consideration that last edition of the Directory is dated 2006, and the share of the standardized of mechanics and electromechanics elements in modern electronic means is constantly reduced to become obvious requirement for engineering methods of settlement estimation of reliability such elements.
Keywords: reliability, designing, electronic means, mechanics and electromechanics elements, mathematical model, failure rate

Pages of history.

• Kashtanov V.A.
  About teachers. Aleksandr Dmitrievich Solov'ev