Redundancy, e.g. structural redundancy, is one of the primary methods of improving the dependability, ensures failsafety and fault tolerance of components, devices and systems. According to the International Patent Classification (IPC), the class of systems and methods G06F11/18 is defined as «using passive fault-masking of the redundant circuits, e.g. by quadrupling or by majority decision circuits». Obviously, «fault-masking» masks not only faults, but failures as well. The majority decision circuits (MDC) in the minimal configuration implements a «2-out-of-3» choice. According to the above definition, such redundancy should not require a special decision circuit. However, that is not always the case. In cases when the resulting signal out of a quadruple logic is delivered to, for instance, an executive device, a «3-outof-4» selection circuit is required anyway. Another dependability-improving solution is defined by class G06F 11/20, «using active fault-masking, e.g. by switching out faulty elements or by switching in spare elements». The word «active» is missing here, thus we have active and passive fault tolerance. The paper examines passive fault tolerance that uses triplication and quadrupling and compares the respective probabilities of no-failure.The Weibull distribution is used that most adequately describes dependability in terms of radiation durability under the effects of heavy ions. It shows that in a number of cases quadrupling has a lower redundancy than triplication. A formula is proposed that describes the conditions of preferability of quadrupling at transistor level.

Aim. The paper examines the problems caused by the conventional interpretation of dependability that prevent the practical use of dependability analysis (assessment) as a tool for engineers involved in the creation of unique highly vital systems and substantiates proposals for their resolution.

Methods. The paper analyzes the problem of quantitative estimation of the dependability of unique highly vital systems without the use of probability statistical models. The view of dependability as a physical property of a product (as a result of changes in its internal state) allows at the physical level ensuring lasting capability to fulfil the required functions and quantitatively estimating the criteria of the required functions’ performance, that can be defined by, for instance, specifying a set of parameters for each function that characterize the capability to perform, as well as the permissible limits of such parameters’ variation. Such approach causes the requirement to take the origin of dependability into consideration and examine the causes of unlikely failures that are to be identified by means of additional analysis in parallel with calculations and experiments performed to support dependability. The solution to the problems of fuzzy terminology allows revealing the interrelation between the quality and the dependability, thus enabling using the single information basis of design and process engineering solutions the analysis, synthesis and assessment of the dependability of unique highly vital systems based on performance parameters without the use of probabilistic statistical models.

Results. The solution of the above dependability-related problems allows ensuring dependability based on the physicality (causal connections) and physical necessity (consistency with the laws of nature) of the causes of failures. The dependability of unique highly vital systems must be ensured from the very early lifecycle stages based on consecutive execution of certain design, process engineering and manufacturing procedures, as well as application of engineering and design analysis of dependability, which also allows solving problems indirectly related to dependability, e.g. improving the quality and reducing the cost of the manufactured products.

Conciusions. The paper shows that the application of design engineering methods for the dependability analysis (assessment) allows within the framework of existing views, yet with certain corrections solving dependability-related problems without the use of the mathematics of the classic dependability theory. High dependability can be achieved by the same ways as undependability comes about, i.e. through design and process engineering solutions. The analysis, substantiation of engineering solutions and specification of necessary and sufficient requirements for the manufacturing process allows achieving the target dependability by engineering means through higher quality of design and process engineering. If we regard dependability as a multiparametric property, parametric models of products can be developed that enable the evaluation of the temporal stability of parameter values using methods of individual design dependability and/or design engineering analysis of dependability. The principles of unity of the design concept and its implementation in manufacture enables the development of products and assessment of their dependability based on a single foundation, i.e. the design and process engineering solutions directly associated with the capabilities of a specific manufacturing facility.

The existence of humankind on Earth largely depends on the energy at its disposal. It is mostly generated by processing minerals extracted from the Earth’s crust by open-cut mining. The quality and low cost of extraction are largely defined by the dependability of employed machines and mechanisms, plants and process engineering solutions. Various types of excavators are the backbone of a mining machine fleet. Their parts that principally interact with the environment (rock) are components of implements, i.e. primarily the buckets and components of bucket(s). It must be noted that in the process of interaction with the environment (rock) the excavator implements and their components are exposed to so-called abrasive wear. Since abrasive wear of implement components (most frequently excavator bucket teeth) causes their recurrent replacement, this inevitably affects the performance of the excavator as a whole and those process flows it is part of. Occasional interruptions of operation and repairs reduce the availability factor, the most important complex indicator of equipment dependability. Given the above, the aim of this paper is to refine the previously known formula proposed more than thirty years ago in VNIISDM (Reysh A.K.) for evaluation of the rate of abrasive wear of excavator bucket teeth. For the first time, with a sufficient accuracy we examined the multitude of operating modes of mining equipment, i.e. operation of excavators in various conditions, e.g. on different soils. Additionally, we extended Reysh’s approach from single-bucket machines to continuous operation multi-bucket ones. For that purpose, the authors used a method of data integration from known sources, method of full-scale experiment under the operating conditions of a specific excavator and method of mathematical simulation (a form of the Monte Carlo method). All of that allowed revising the values of the parameters in the Reysh formula. The refined formula that we obtained can now be used for the dependability evaluation of machines operating under varying conditions, as well as for the purpose of appointing the time of preventive inspections.

The Aim of this paper is to study the effect of the structural features of pipeline systems on the development of emergency situations by the mechanism of progressive blocking of transportation nodes. The blocking of an individual point element of a system is considered as the result of simultaneous failure of all the pipelines converging into the node. The process of progressive blocking of a certain set of nodes of a pipeline system in random order is called a progressive blocking. The development of progressive blocking is associated with the disconnection of the consumers from the source of end product and is a dangerous scenario of emergency development. The system’s resilience against progressive blocking is estimated by the resilience indicator F„, the average share of the system’s nodes whose blocking in a random order causes the disconnection of all consumers from the source of the end product.

Methods of research. The values of 0 <F„< 1 were identified by means of computer simulation. After each fact of damage associated with a random blocking of an individual node, the connection between the source and consumers of the end product was established. The statistical characteristics of the process of progressive blocking were evaluated according to the results of repeated simulation of the procedure of damage of the analyzed network structure. In general, the structure of a pipeline system is characterized by a graph that describes the connections between point elements. The valence of an individual graph node is the number of edges that converge into it. Similarly, the valence of the respective network node is the number of converging linear elements (pipelines). Furthermore, an important characteristic of an individual node is the composition of the converging linear elements. Thus, the set of a system’s linear elements includes the following varieties that ensure the connection between: the source and the consumer (subset G1), two consumers (subset G2), a consumer and a hub (subset G3), two hubs (subset G4), the source and a hub (subset G5).

Results. The author analyzed and examined the effect of the structural characteristics on the ability of pipeline systems to resist the development of emergency situations through the mechanism of progressive blocking of nodes. It was established that with regard to structural optimization the most pronounces positive effect associated with the increase of the values F^ is observed as the valence of the source node grows and additional linear elements of subset G1 are included in the system.

Conclusions. The process of progressive blocking of pipeline transportation system nodes is a hazardous development scenario of an emergency situation. The most efficient method of improving pipeline system resilience against progressive blocking consists in increasing the valence of the source node and inclusion of additional linear elements of subset G1 in the system. Structural optimization of pipeline systems should be achieved by defining the values F^ for each of the alternatives with subsequent adoption of a substantiated design solution.

The Aim of this paper consists in the development of a method of improving the functional dependability of the control systems of unmanned aerial vehicles (UAV CS) affected by electromagnetic effects in flight and failures within the functional component of the onboard test instrumentation (OBTI).That is achieved through the identification of the failed functional element, the functional component of OBTI, the capability of performing the target objective of the UAV CS and decision-making regarding the initiation of the flexible operation algorithm. The existing and future UAV CS under development use binary reliability models, i.e. two states are distinguished: up and disabled. Therefore, each in-flight failure is classified as the UAV CS failure regardless of the current mission. If we regard a CS as a multifunctional system, it becomes obvious that the failure of not any UAV CS functional element causes flight termination.

Methods. Solving the problem involved the use of a CS diagnostic model in the form of binary relations between the control actions and combinatorial subsets of functional elements, risk of losses estimation method as part of improving the functional dependability of UAV CS in flight, decision theory and combined branch-and-bound method. The mission performance probability is used as the efficiency criterion. This criterion is applicable when changes in a UAV CS’ characteristics cause only partial reduction of the functional efficiency.

Results. The purpose of CBTI self-supervision is failure location with the depth that allows determining its ability to perform the basic operations with the probability not lower than required by the customer, as well as the allowed set of elementary checks (EC) in this case. Based on the current results of elementary self-checks (ESC), one of the following decisions can be taken: stop the checks and discard CBTI; continue location; stop failure location and continue UAV CS mission per modified algorithm. At each stage of failure location in CBTI, based on the results of ESC, the area of covering check (ACC) and part of set suspected of failure (PSSF) are analyzed, which includes verifying the ACC for sufficient coverage of the PSSF, based on which appropriate decisions are taken. The following areas are formed: the area of observable data (processes of changes in the ACC and PSSF areas), within which the decision is taken to continue the checks, and the area, within which it is finally decided to terminate the checks. If It Is decided to continue the failure location, another ESC is selected, which Is associated with the risk of loss. The probability of false discarding of CBTI due to ESC selected out of ACC Is taken as the risk of loss. The moment of termination of CBTI self-supervision depends not only on the set of decisions, but their sequence as well. Thus, the task at hand comes down to designing the optimal ESC strategy that minimizes the probability of false discarding. The idea of combined branch-and-bound method (CBBM) as part of the design of the optimal CBTI self-supervision algorithm consists in the consecutive selection at each stage of ESC implementation process, out of the subset of minimum risk checks of the next ESC till a one-element subset is obtained and/or the corresponding decision is taken.

Conclusions. The developed method allows continuing the performance of the target objectives of a UAV CS In flight when affected by failures In CBTI.

As it is known, load-lifting rail cranes of various models employed as part of Russian Railways repair and recovery trains are high-risk facilities. They normally have large dimensions and powerful engines that generate significant thrust and high energy. The paper examines the effects of harmful occupational factors of physical nature, i.e. industrial noise and vibration on the performance and health of rail crane operators.

Aim. Based on the analysis of the causes of incidents that occurred in the course of operation of rail cranes, generalizing the experimental findings regarding the effects of industrial noise and vibration on crane operators and identifying the correlation between the clinical signs of distress in this category of workers and the levels of the above harmful physical industrial factors.

Methods. Experimental studies and the subsequent evaluation of the effect of industrial noise and vibration generated by the mechanisms of cranes were conducted with the use of an Assistant Total+ noise and vibration analyzer in the course of operation of rail cranes of various models when handling cargo, as well as when crane engines idle. Measurements were conducted at workstations where the operator is to be at during the operation and maintenance of the crane, i.e. the control cabins, operator seat, control handles, near the crane engine.

Results. The paper provides a classification of sources of noise and vibration that affect crane operators, experimental findings regarding the levels of industrial noise, general and local industrial vibration for various models of cranes. Clinical signs of distress are identified, a list is set forth of the most typical occupational health problems for this category of workers.

Conclusions. The paper concludes that the reduction of industrial noise and vibration caused by the mechanisms of rail cranes is a relevant engineering and socioeconomic problem. From the socioeconomic point of view the solution to this problem will allow improving the working conditions of crane operators, while in terms of engineering it will enable higher technical and operational characteristics of crane mechanisms.

The research used the Thomas-Kilman Conflict Mode Instrument (TKI) (more specifically, TKI-R, the Russian adaptation by N.V. Grishina) psychodiagnostic procedure to assess the behaviour strategy in conflict situations, as well as the Buss-Durkee Inventory to determine the tendency of subjects to various forms of aggressive behaviour. Statistical processing of the findings was done using the Bravais-Pearson correlation coefficient and Pearson’s criterion.

Results. At the first stage of the multipurpose experiment 48 student dispatchers were surveyed, at the second stage the total of 603 subjects were surveyed (students of the Saint Petersburg State University of Civil Aviation and the Institute of Philology, Foreign Languages and Media Communications of the Irkutsk State University), i.e. while emphasizing operator professions in order to improve the validity of the experiment the sample was significantly extended to include, among others, students of the humanities. It was found that the results of the Buss-Durkee Inventory have an inverse correlation with the tendency to an adaptation strategy and direct correlation with the tendency to rivalry and collaboration strategies. According to Pearson’s fitting criterion, there are significant differences in the manifestation of such behaviour styles as rivalry and avoidance between pilot and humanities students, while for the samples of males and females the differences are in the manifestation of such behaviour stiles as rivalry, avoidance and compromise. Females are significantly less inclined to rivalry and somewhat more inclined to avoidance and compromise as compared to males. There are also no observable crucial differences between the intercorrelations of the TKI-R results of the first and second stages of the experiment. The authors’ findings were compared with the published results of the survey of the students of the Tuvan State University and Yaroslavl State Medical University, as well as with the results of surveys of athletes and business owners.

Conclusions. By generalizing own findings and those set forth in other authors’ publications, we can conclude that uncooperative behaviour of all tested students is dominated by average manifestation of strategies of competing, collaborating, compromising, avoiding and accommodating, which indicates the ability of the subjects of this age for flexible behaviour in conflict situations subject to the specific conditions of interaction. That means that students, unlike the success-seeking business owners, while prioritizing collaboration and compromise in conflict situations, flexibly use other behaviour strategies. This must be taken into consideration when planning measures aimed at improving the reliability of professional psychological selection in commercial aviation. It appears that in view of the above reasons, the application of the TKI-R procedure in the professional psychological selection of aviation specialists is unviable.

Aim.The development of the Russian railway industry is associated with the growing number of operated buildings, rolling stock, more complex business processes of infrastructure maintenance and client service. In this context, JSC Russian Railways (JSC RZD) needs to manage the fire safety of more than ten thousand units of traction rolling stock and hundreds of buildings, where potential fires may cause harm to passengers or interruption of service. Fire safety management of both fixed and mobile railway facilities is performed at all lifecycle stages from design to disposal. Implementing the processes of fire safety diagnostics and prediction requires the development of a man-machine system whose core would be an automated fire risk control system (ACS) that allows – basedon the fire risk prediction – makingdecisions regarding the requirement for the repairs, replacement or maintenance of railway facilities and fire safety systems. 

Methods.The methods of the automatic control theory, expert assessment were used. The study aimed to develop an algorithm of automated auditing of railway facilities fire safety. 

Results.It is established that the majority fire safety control systems use gas concentration sensors to detect symptoms of hazard before flame development. This approach is hardly effective in terms of fire safety of railway facilities. For railway facilities whose actual state has an effect on the probability of fire a fire audit algorithm was developed that is based on the existing service and repair system, as well as statistical data on the states of railway facilities that precede fire. In order to enable systematic risk management measures in a large number of railway facilities, the paper proposes the structure of an automated fire risks management system that includes a fire safety management center and a mobile hardware and software system for fire safety auditing. 

Conclusions. It shows the importance of developing a proactive fire safety management system based on fire risk assessment. It was identified that information on the states preceding fires in railway facilities can be obtained from both the existing automated failure reporting and risk assessment systems and the diagnostic results of the actual state of objects as part of scheduled preventive maintenance. A method of automated assessment of fire hazard is proposed for systematic management of fire risks in many railway facilities.