Trishch, Roman

Aircraft maintenance (AM) is a set of operations at the operational stage to maintain airworthiness, the purpose of which is to prepare the aircraft for flights, maintain serviceability, etc. The analysis of possible failures and their consequences during maintenance is carried out “from top to bottom”. As a result of the decomposition, the presence of defects in functional subsystems is analysed. For the coordinated execution of operation processes, it is advisable to use simulation modelling. Therefore, the task of creating a simulation model of technical maintenance and repair of automatic transmission lines, which includes modules for diagnosis, fault finding, accumulation of diagnostic information for further processing, etc., is set and solved. The purpose of the study is to develop a model of multi-level component search for aircraft malfunctions during diagnostic pro-cesses. The subject of the research is the planning and management of operation as a stage of the life cycle of complex equipment. The following mathematical models and methods are used: system analysis, information theory, simulation modelling. A model of multi-level component fault finding during the diagnostics of the automatic transmission system is proposed, which will allow to optimize the duration and cost of maintenance of operational equipment.

The existing functional dependencies between the measured values of quality indicators and their assessment on the dimensionless scale that were used to assess qualimetry objects of various nature have been analyzed. It has been shown that, as a rule, non-linear dependencies should be used for the objective assessment of qualimetry objects. The main task of the researcher is to choose the type of nonlinear dependence, this requires additional scientific research. The tool for choosing one or another non-linear dependence is the understanding of the physical essence of the qualimetry object, that is, the understanding of the regularities of the relationship between the measured value of qualimetry indicators and their assessment. For this, it is important to use methods of expert assessments, because, as a rule, such regularities are unknown. The functional dependence that is used to obtain assessments of indicators of the state of occupational safety in production is stepwise and includes a shape parameter. When the shape parameter changes, the curvature of the dependence changes, thereby changing the assessment on the dimensionless scale. This feature of the applied dependence makes it possible to develop a universal technique, that is, by changing the shape parameter, this dependence can be applied to various indicators of labor safety in any production. As an example, the article examines the machine-building industry and assesses the most dangerous factors. A step-by-step technique for determining a complex indicator of occupational safety in production has been developed, and its effectiveness and universality have been shown by an example of measured numerical values of dangerous factors.

Consumers are increasingly questioning the quality of food products, especially meat, demanding reliable information about its freshness and safety. Traditional methods of assessing meat freshness, such as organoleptic and laboratory methods may be limited and time-consuming. This has led to the need for the development of effective and rapid methods for determining the freshness of meat. In this context, the relevance of using modern technologies, including neural networks, for meat freshness identification arises. Neural networks, which have become powerful tools in data processing and analysis, can provide precise and automated methods for determining the quality of food products. This research proposes combining a sensory network and a neural network to create a smart meat quality control system. This system integrates gas sensors and a color sensor, with the software using a neural network for analysis and decision-making. The authors have proposed the structure of the smart system, its principles of operation, features of the architecture, and the training of the neural network. The authors present the hardware and software components of the meat control and identification system. The project involves the integration of sensors, an Arduino microcontroller, and a Raspberry Pi single-board computer to implement a system capable of accurately and reliably identifying the freshness of meat.

An experimental study was performed to investigate the effect of macrogeometric parameters of the mating surface forms on the strength of the cylindrical interference fit joint: taper, bow, barrel, and ovality. Fifteen couplings were made with a nominal diameter of 60 mm and a mating surface length of 70 mm. The bushings had a regular cylindrical form, and the CNC machining of shafts caused the geometry error. The relative geometric accuracy of the form was assumed to be the maximum allowable and was up to 60% of the tolerance zone. During modeling, the minimum allowable interference fit in the coupling Ø60 H8/u8 was assumed to be 0.04 mm to enhance the effect of form geometry errors. Ranked assembly was used to compensate for the interference fit in joints. The joints were assembled using thermal assembly. The strength was determined by axial pressing on the press with the press diagram recorded. The experiment results showed that form geometry error with maximum allowable values significantly affects the strength of the cylindrical interference fit. The taper reduces the strength to 0.87, barrel to 0.8, bow to 0.59, and ovality to 0.79 of coupling with perfect cylindrical surface geometry. Comparison of experimental results with those previously obtained by finite element modeling showed good agreement, within 10%. It is recommended that for critical couplings, a stricter limitation of the geometric error of the mating surfaces shall be provided.

The study aims to improve the quality of the thermal assembly technology of engineering elements by introducing a methodology for determining the size of the closing link in the calculation of assembly dimensional chains, taking into account the influence of temperature gaps. The presented analysis of the technological preparation of production revealed the need to include the calculation of dimensional chains as one of the elements of dimensional analysis, which is determined by a set of calculation and analytical procedures carried out during the development and analysis of structures and technological processes. The effectiveness of dimensional chain calculation using the probabilistic method largely depends on the extent to which the influence of random factors on the values of the component links and the closing link is considered. Studies have confirmed that the calculation of the nominal value of the closing link does not meet the requirements set forth when compared with the results obtained during the calculation without considering the influence of temperature gaps. However, the practical assembly of the feed pump rotor, taking into account the influence of temperature gaps, can lead to an improvement in the axial assembly accuracy by 5% to 13% and a decrease in the gap between the ends of the rotor wheel and the discharge disk by 6% to 10% without the need to use additional technological equipment.

Requirements of the international standard ISO 45001:2018 were analysed to identify the need for monitoring, measuring and analysing the functioning of the occupational health and safety management system. This analysis has made it clear that the effectiveness of the development and implementation of the occupational health and safety management system depends on the assessment methodology. The study focused on existing studies and publications on the assessment of processes, including those related to occupational safety, assessment methods or qualitative methods, and statistical methods used for assessment. As a result, the topic has been proven relevant, and the goal of the article was determined: to study the possibility of using qualimetric methods for evaluating the labour safety management system. A survey was conducted among workers at a machine-building enterprise to evaluate the occupational health and safety management system. Verbal scales were proposed to process the study results as they allow quantitative ratings to be obtained on the coded scale of the desirability function. The study result is a technique for obtaining a quantitative assessment of the occupational health and safety management system. This technique is universal and can be applied to any enterprise. It can also be used to make managerial decisions regarding the improvement of the occupational health and safety management system.

Assessment of occupational safety risks at work is a requirement of the Occupational Health and Safety Management System, which is regulated by international standards. For quantitative risk assessment, it is proposed to use qualimetric methods. It is proposed to obtain estimates of hazardous factors on a dimensionless scale using the error function (erf). Knowing the density function of the law of distribution of random variables of quantitative values of negative factors, the density function of their estimates on a dimensionless scale was obtained. Functionally dependent statistics were obtained. The density function makes it possible to determine the risk of a hazardous factor score falling into the hazardous assessment interval.

The study discusses approaches to assessing the quality of sustainable development indicators and analyses sustainable development indicators in general, for which the desirability function and the approach of translating sustainable development indicators into a dimensionless scale are used. This approach makes it possible to analyse the processes of achieving the sustainable development goals and relevant tasks on the basis of statistical data, as well as to compare indicators with different characteristics. For the purpose of qualimetric assessment, the article proposes to divide the indicators of sustainable development into four groups characterized by the following parameters: the lowest value is the best, the highest value is the best, the average value is the best, and the values that simultaneously tend to the lowest and the highest. It is proposed to evaluate sustainable development indicators in accordance with the group, taking into account the significance of the indicator, for which the form parameter and the evaluation step are selected by the expert evaluation method. For example, several sustainable development indicators for different groups are presented, and calculations are made to determine the dimensionless indicator, taking into account its significance according to the opinion of experts. As a result, we obtained dimensionless values for each of the sustainable development indicators (FQ = 0.92, 0.98, 0.86, 0.28, and 0.54), which characterize the achievement of sustainable development goals and allow us to assess progress in both a prospective and retrospective context.

Investment, the entry of foreign firms depends of a large extent on the country’s goodwill, which is reflected in various ratings. This representation of the situation is approximate, as it does not estimate the differences between the values of the indicators with adjacent grades. This can be avoided by dividing countries into homogeneous groups. It is appropriate to do so on the basis of non-linear grouping rather than linear grouping. It is based on the transformation of data into a dimensionless scale and linear grouping. In the case, its homogeneity increases thanks to the level-ling of the most distinctive values and the alignment of the statistical characteristics of the groups. The aim of the article is to propose in principle, a new approach to the ranking of countries on the basis of their level of economic development. It was found that the nonlinear decision of countries into homogenous groups and compared to the linear grouping more accurately reflect the current situation.