Pipeline transportation systems are used in various industries for the purpose of delivering various substances and materials to consumers. If, as the result of an accident development, a certain number of random linear elements (pipelines) consecutively fail, such scenario of events is called progressive damage. If several pipelines converging at a node fail simultaneously, such point element of the system is blocked. Progressive blocking of a certain set of nodes of a pipeline system in random order is called a progressive blocking. Simultaneous development within a system of progressive damage to linear elements and blocking of transportation nodes represents mixed damage. Mixed damage is a hazardous form of emergency, and its development causes fast degradation of a system’s transportation capabilities.

The Aim of the paper is to study the characteristic properties and patterns of the progress of mixed damage affecting network structures of pipeline systems, as well as evaluating such systems’ capability to resist its development.

Methods of research. The characteristics of network entities’ resilience to the development of mixed damage were identified by means of computer simulation. The nature of the effects to which a system is exposed was defined with a cyclogram, whose integer parameters indicate the alternation of the process of sequential damage of linear elements and nodes of a network structure.

Results. It has been established that a correct comparison of the resilience of various network structures to mixed damage is only possible with regard to comparable facilities. For that purpose, the analyzed systems must have identical numbers of nodes, linear elements and end product consumers. Additionally, such systems must be exposed to effects with identical cyclograms. It is shown that the correlation of the resilience of comparable network structures does not depend on the specific type of mixed damage cyclogram, but is defined by the nature of the connections within a particular system.

Conclusions. Mixed damage is a hazardous development scenario of an emergency situation that is associated with rapid degradation of the transportation capacity of pipeline systems. The ability of network structures of pipeline systems to resist mixed damage is evaluated based on indicators that are defined by means of simulation. A correct comparison of the resilience of various structures to mixed damage is only possible in case they are comparable. For that purpose, they must have identical numbers of nodes, linear elements and product consumers. Additionally, such systems must be exposed to damage procedures with identical cyclograms. The correlation of the resilience of network structures that comply with the comparability conditions does not depend on the adopted damage cyclogram, but is defined by the existing set of connections within a particular system.

The Aim of the paper consists in improving the efficiency of dependability indicator estimation for the plan of tests with addition, i.e. probability of no-failure and mean time to failure. Due to economic considerations, determinative dependability tests of highly dependable and costly products involve minimal numbers of products, expecting failure-free testing or testing with one failure, thus minimizing the number of tested products. The latter case is most interesting. By selecting specific values of the acceptance number Q and number of tested products, the tester performs a preliminary estimation of the dependability indicator, while selecting Q = 1 the tester minimizes the risks caused by an unlikely random failure. However, as the value Q grows, the number of tested products does so as well, which makes the testing costly. Therefore, the reduction of the number of products tested for dependability is the firstpriory problem and, in this context, economic planning of testing with addition is becoming increasingly important. We will consider binomial tests (original sample) with addition of one product (oversampling) to testing in case of failure of any of the initially submitted products. Testing ends when all submitted products have been tested with any outcome (original sampling and oversampling). Hereinafter it is understood that the testing time is identical for all products. Testing with the acceptance number of failures greater than zero (Q > 0) conducted with addition allows reducing the number of tested products through successful testing of the original sample.

Methods. Efficient estimation is based on the integral approach formulated in many papers. The integral approach is based on the formulation of the rule of efficient estimate selection specified on the vertical sum of absolute (or relative) biases of estimates selected out of a certain set based on the distribution law parameter, where n is the number of products initially submitted to testing. The criterion of selection of an efficient estimate of the probability of failure (or PNF) at a set of estimates is based on the total square of absolute (or relative) biases of the mathematical expectation of estimates from probability of failure p for all possible values of p, n.

Conclusions. The paper examines the probability of no-failure estimates for the plan of tests with addition. For the case of n > 3, the estimates and composite estimate are more efficient in comparison with estimate . The composite estimate of the probability of no-failure should be used in failure-free tests. For the case of n > 3, testing with the acceptance number of failures greater than zero (Q > 0) conducted with addition allows reducing the number of tested products through successful testing of the original sample. The composite estimate of the mean time to failure is bias-efficient among the proposed mean time to failure estimates. The obtained composite estimates and are of practical significance in the context of failure-free testing with addition.

The stress that affects structures and their mechanical and geometrical parameters are random values. For that reason, the dependability of a construction facility (technical system) is generally evaluated in terms of the probability of no-failure over the estimated period of operation. The paper shows the feasibility of dependability analysis of building systems in the course of their design using logical and probabilistic methods, presents algorithms for regulating their dependability. It examines the feasibility of assuring the dependability of a construction project using the example of a double-span whole hinged beam. The paper also establishes the requirement of accounting for all possible destruction models of a building system. The dependability of a double-span whole hinged beam is estimated based on the probability of non-occurrence of all possible destruction models or one of a set of possible kinematic mechanisms. A kinematic mechanism forms a chain of plastic hinges or a chain of progressive failures of effective sections. In other words, the task of preventing progressive collapse comes down to ensuring the required dependability of both the building as a whole, and its individual members (effective sections) by adjusting qualitative and quantitative indicators of the dependability structure. The dependability of a member is understood as its ability to maintain internal force within the effective section at least as high as the external force. It is shown that correct design solutions, rational choice of materials and load non-exceedance probabilities enables specified dependability of a building system. In some cases that allows saving materials, in others enables lower probabilities of failure. Constructing the dependability structure of a technical system enables a quantitative estimation of the most hazardous design models of destruction, rational management of the choice of safety factors of load bearing members, redistribution of such safety factors, thus preventing progressive collapse. The introduced differential characteristics of the members’ “weight”, “significance”, “contribution” and “specific contribution” allows demonstrating the distribution of the roles of each member within the specified structure in terms of specific problems, including accounting for the possibility of progressive collapse. The study has shown that the removal of undependable vertical load bearing structures does not solve the problem of dependability of a construction project, including protection against progressive collapse. It has been established that the design of structures, including in terms of considerations of progressive failure, must involve constructing a system dependability structure using kinematic analysis, identifying the most important and significant members of such structure and – using special adjustment techniques – obtaining the required structure dependability. That will enable significant resource saving and reduction of costs associated with the development of construction operations.

Historically, dependability services originated within design units of companies. A design engineer had his/her own ideas about the quality control of released products. As the initial application field of the dependability theory was the aerospace industry, he/she understood that the presence of errors and omissions within a product could cause catastrophic consequences [1]. Along with the dependability unit the quality and technical supervision service was developing, and that was primarily tasked with organizing and conducting acceptance testing, receiving inspection and prevention of a product’s non-compliance with technical documentation. At one point, a conflict arouse between the two branches, which lead to a general misunderstanding of responsibilities and disorganization of the product dependability control. As a result, in some companies the dependability service is integrated with the quality service, in others it is subordinated to the design bureau. Additionally, operational dependability evaluation requires an uninterruptible source of reliable information on the reliability and maintainability of the equipment. The quality of this information depends on the interaction between the dependability service and the maintenance service. The latter is to compare the repair reports that specify the recovery time and operation time of the product and promptly submit that data for dependability calculation. Thus, the following questions arise: which activities are to be performed by the dependability service, who is to be subordinated to whom, who is the owner of the processes associated with the estimation of dependability parameters? It is important to understand the purpose of establishing a dependability unit in a company, what authority its employees possess, what results the management expects to obtain. The formalization of the research findings presents a problem. As of today, there is no single approach to formalized calculations, preparation of dependability analysis reports. The research findings are to be sent to all the involved business units, therefore a convenient form of information representation must be developed. A special attention must be given to personnel training in terms of technical system dependability. Industrial products become more and more complex, new technologies are developed, and old approaches to dependability calculation and analysis do not always ensure acceptable results. That is not surprising, as the significance of the use of reliable and substantiated methods of dependability estimation is very understated. That is due to the fact, that many believe that the dependability theory is based on the research of the physical, design-specific causes of failure, physicochemical processes, etc., meaning that a dependability engineer is first and foremost a design or process engineer. However, it should not be forgotten that the general dependability theory is subdivided into the mathematical (mathematical methods of the probability theory), statistical (method of mathematical statistics) and physical (research of materials properties variations). Subsequently, a dependability service is to conduct analysis based on competent application of mathematics alongside activities associated with products design research. Proposals regarding future developments in this area, including the education system, will be welcome.

Aim. To propose an approach to the organization of the dependability service in a modern machine-building company taking into account advanced methods and concepts of dependability analysis at all lifecycle stages of a product.

Conclusions. The paper suggests an organizational structure of a dependability unit for a transport machine building company. The interactions between the dependability service and other business units is examined. A number of factors affecting the efficient operation of the dependability service are identified.

The paper describes the design concept of the DIALOG simulation software suite (SSS) intended for calculating the dependability indicators of electronic systems (ES) of random configuration, as well as solving problems associated with assuring the functional dependability of such systems. The DIALOG SSS employs a specially designed DIALOG-SINTEZ technology that enables automatic synthesis of event simulation models in the form of programs in the selected programming language. In DIALOG SSS, the input data include: system composition in the form of a combination of conventional blocks; criteria of failure event occurrence and repairs; random value parameters (failures of system components in various modes of operation, SPTA requests, etc.); stages of system operation and types of repairs; list of calculated indicators. For the purpose of ensuring the required indicators, the simulation models undergo statistical testing under modified indicators of random values in each new test. Based on the accumulated results of all the performed tests the required indicators are calculated. The DIALOG SSS consists of four components: DIALOG-NRS is intended for the calculation of dependability indicators of non-repairable redundant systems; DIALOG-RRS is intended for the calculation of dependability indicators of repairable redundant systems, as well as the number of and cost of warranty repairs; DIALOG-ZIP-NS is intended for SPTA sets calculation for simple non-redundant systems; DIALOG-ZIP-RS is intended for SPTA sets calculation for any redundant systems. SPTA set calculation is normally done using standard procedures described in regulatory documents. In solving the direct problem of optimal SPTA set calculation, the input data includes the required value of one of the two SPTA sufficiency indicators (SI) and type of costs that are to be optimized (minimized) in order to achieve the target values of SI. In solving the inverse problem of optimal SPTA set calculation, it is required to ensure the specified costs of the initial SPTA supply. As the SPTA supply SI, the mean spare parts (SP) supply delay time out of SPTA Δt_d.SPTA and SPTA availability coefficient C_a.SPTA are used. SPTA optimization using the DIALOG-ZIP SSS allows improving user options through the following additional characteristics: SPTA SP failure logging; optimization of SP count and accounting for the their characteristic features for the purpose of SP emergency delivery (ED); capability to use products with any type of redundancy; when using SPTA-G group set, capability to include differently-structured products into ESs. The paper sets forth the structure diagram of the DIALOG SSS programs interaction, that implies three modes of operation of the simulation model: SI calculation for specific SPTA contents; calculation of preliminary SPTA supply before the beginning of optimization; calculation of optimal SPTA set. The authors examine the matters related to the selection of the required number and duration of simulation model testing.

The Aim. This paper examines the problem of reliability of aptitude screening currently in place in commercial aviation in terms of its indiscriminate applicability to males and females. The task consisted in evaluating some professionally important qualities in males and females, who have successfully completed aptitude screening while being admitted to the aviation school, and identify the presence or absence of differences between the obtained results. For that purpose, a research was conducted that involved 60 third-year traffic controller students of the Saint Petersburg State University of Civil Aviation (35 males and 25 females).

Methods. The psychodiagnostic method included the Prognoz-1 and Prognoz-2 stress tolerance evaluation forms developed in the S.M. Kirov Military Medical Academy, H.J. Eysenck intellectual development test, A. Buss and A. Durkee hostility assessment forms. The authors’ earlier findings were also used. Statistical processing was performed using correlation analysis and Pearson’s chi-squared test.

Results. The analysis of psychodiagnostic findings has shown the absence of positive differences in the intellectual development of males and females in the observed group. In general, the intelligence of the study participants was sufficiently high (121.17 average IQ for males and 123.04 for females). The assessment of the stress tolerance of the surveyed group using two different variants of the Prognoz forms also has not identified any significant differences between males and females (stress tolerance of females is somewhat lower, than that of males, but the identified difference is obviously not crucial). However, both among males (1 person) and females (1 person) participants were identified, for whom the prediction per both diagnostic method was “unfavourable”. Positive differences between the examined males and females were identified in terms of tendency towards physical aggression (A. Buss and A. Durkee test).

Conclusions. The psychodiagnostic method used as part of this work have not identified fundamental gender differences. An exception is the tendency towards physical aggression. In females this indicator is clearly lower, though there are girls who display high aggressiveness. Most experimental subjects demonstrated high stress tolerance and sufficiently high level of intellectual development. And while the examined group does not display clear differences in IQ (there are reasons to believe that the larger is the surveyed group the less significant are the positive differences between males and females in terms of intellectual development), however, the trend of female aviation specialists having overall higher IQ can be observed. The research must continue, extending the range of assessment methods, including alternative approaches that do not involve personality inventories, while simultaneously evaluating the extent of professionally important psychological qualities of aviation specialists, yet not with respect to gender, but in accordance with a candidate’s identified gender type.

Aim. This paper aims to compare the two primary approaches to ensuring the structural strength and safety of potentially hazardous facilities, i.e. the deterministic approach that is based on ensuring standard values of a strength margin per primary limit state mechanisms, and the probabilistic approach, under which the strength condition criterion is the nonexceedance by the target values of probability of damage per various damage modes of the standard maximum allowable values.

. The key problem of ensuring the structural strength is the high level of uncertainties that are conventionally subdivided into two types: (1) the uncertainties due to the natural variation of the parameters that define the load-carrying ability of a system and the load it is exposed to, and (2) the uncertainties due to the human factor (the limited nature of human knowledge of a system and possibility of human error at various stages of system operation). The methods of uncertainty mitigation depend on the approach applied to strength assurance: under the deterministic approach the random variables “load” and “carrying capacity” are replaced with deterministic values, i.e. their mathematical expectations, while the fulfillment of the strength conditions subject to uncertainties is ensured by introducing the condition that the relation of the mathematical expectation of the loadcarrying capacity and strength must exceed the standard value of strength margin that, in turn, must be greater than unity. As part of the probabilistic approach, the structural strength is assumed to be ensured if the estimated probability of damage per the given mechanism of limit state attainment does not exceed the standard value of the probability of damage.

Conclusions. The two approaches (deterministic and probabilistic) can be deemed equivalent only in particular cases. The disadvantage of both is the limited capability to mitigate the uncertainties of the second type defined by the effects of the human factor, as well as the absence of a correct procedure of accounting for the severity of consequences caused by the attainment of the limit state. The above disadvantages can be overcome if risk-based methods are used in ensuring structural strength and safety. Such methods allow considering uncertainties of the second type and explicitly taking into consideration the criticality of consequences of facility destruction.

The Aim of the paper is to show that the risk to critical infrastructure facilities (CIF) of structurally complex systems (SCS) should be considered as a multicomponent vector, whose set of parameters is subject to changes. Real safety estimation using the risk-oriented approach is impossible without a sufficient base of quantitative and qualitative characteristics of risk factors, as well as data on the status of facilities and processes that are exposed to such risk factors. Risk assessment always aims to estimate its quantitative indicators, which allows it to be used not only to assess industrial safety, but also to substantiate the economic efficiency of taken measures, conduct economic calculations of the required relief or compensation of lost health of workers and environmental damage.

Method. The author suggests a method of risk synthesis (with game definition of the problem of countering possible external effects of various nature on CIF SCS) as one of the foundations of the design of advanced systems for monitoring safety threats to SCS. A special attention must be given to the effect of risk factors on the system of balanced safety and risk indicators, as prediction based on single indicators does not create a holistic image of the systems’ status and development trends.

Result. Key methodological premises were formulated: from general problem definition of safety management through the synthesis the model of a controlled facility and its external and internal connections, solution to the problem of selection of priority protection facilities in terms of assuring efficient operation and general safety of SCS. As the basis of advanced systems for monitoring safety threats and risks, the paper suggests the concept of risk management aiming to create the mechanism, method and tools for the synthesis, analysis and prediction of emergency risks.

Conclusion. The proposed method can be applied to a wide range of tasks of primary analysis, synthesis and quantitative estimation of the CIF-related risks and safety management of SCS of various purpose.