Vladimir A. Rodionov

Identifying and assessing the most critical work-related hazards is essential for implementing effective corrective actions through Occupational Health and Safety Risk Assessment (OHSRA). Due to the inherent ambiguity of human judgment, it is often difficult to evaluate occupational risks using precise numerical values during the OHSRA process. To address this challenge, various mathematical techniques have been developed to support risk-based decision-making by managing uncertainty, identifying optimal solutions, and ranking alternatives. This study introduces a novel OHSRA model for assessing and prioritizing occupational hazards, integrating Modified Failure Mode and Effects Analysis (MFMEA), Shannon entropy, and the Combined Compromise Solution (CoCoSo) method. Specifically, the risk assessment is based on five criteria: severity (S), occurrence (O), detectability (D), prevention (P), and cost (C). To manage the complexity and vagueness of expert evaluations, Shannon entropy is used to determine the weights of the criteria, while the CoCoSo method ranks the identified hazards. The robustness of the proposed framework is evaluated through a one-at-a-time (OAT) sensitivity analysis by varying each criterion weight by ±0.05, ±0.10, and ±0.20. A case study of the stone crusher unit in the ceramic industry showcases the practical applicability of the proposed methodology. The key advantages of the proposed approach include its flexibility in handling complex expert data and its effectiveness in delivering reliable and discriminative risk evaluations of occupational hazards.

Relevance. The need to improve methods for calculating the operating parameters of jet fans in mine workings. The use of jet fans operating without air stopping is a promising option for increasing the efficiency of ventilation of large-section mine working systems. Operational analysis of the effectiveness of the selected parameters of jet fans and mixing chambers is possible only if there are sufficiently universal and accurate methods for calculating equivalent characteristics. While the approaches existing today have, as a rule, only one of the above properties. Aim. To determine the patterns of changes in the aerodynamic parameters of the air flow as it moves through a mine working with the jet fan operating without air stopping. Objects. Air flows generated in a large-section mine working as a result of the operation of the jet fan with a mixing chamber. Methods. Three-dimensional numerical simulation of steady-state turbulent air flow in a mine working, comparative analysis of calculation results for different locations of the jet fan, comparative analysis of numerically calculated equivalent characteristics of the jet fan with an analytical formula. Results. The authors have determined the patterns of changes in mechanical energy and static pressure of the air flow as it moves along the mine working. Multiparameter numerical simulation for various airflow rates at the entrance to the mine working made it possible to obtain equivalent pressure characteristics of the VM-8 jet fan with a mixing chamber, which can be used in one-dimensional calculations of the steady-state distribution of flow rates in the mine ventilation networks. A comparative analysis of simulation data with a known analytical dependence of the pressure drop made it possible to determine the directions for further improvement of analytical methods for describing air flow in mine workings with jet fans equipped with mixing chambers.

The results of the analysis of statistical data on accidents at Russian mines caused by explosions in the workings space have shown that explosions of methane-dust-air mixtures at underground coal mines are the most severe accidents in terms of consequences. A detailed analysis of literature sources showed that in the total number of explosions prevails total share of hybrid mixtures, i.e. with the simultaneous participation of gas (methane) and coal dust, as well as explosions with the possible or partial involvement of coal dust. The main causes contributing to the occurrence and development of dust-air mixture explosions, including irregular monitoring of by mine engineers and technicians of the schedule of dust explosion protective measures; unreliable assessment of the dust situation, etc., are given. The main problem in this case was the difficulty of determining the location and volume of dust deposition zones in not extinguished and difficult to access for instrumental control workings. Determination of the class-shape of coal dust particles is a necessary condition for constructing a model of the dust situation reflecting the aerosol distribution in the workings space. The morphological composition of coal mine dust fractions with dispersion less than 0.1 has been studied. Particle studies conducted using an LEICA DM 4000 optical microscope and IMAGE SCOPE M software made it possible to establish the different class-shapes of dust particles found in operating mines. It was found that the coal dust particles presented in the samples correspond to the parallelepiped shape to the greatest extent. The mathematical model based on the specialized ANSYS FLUENT complex, in which this class-form is incorporated, is used for predicting the distribution of explosive and combustible coal dust in the workings space. The use of the obtained model in production conditions will allow to determine the possible places of dust deposition and to develop measures to prevent the transition of coal dust from the aerogel state to the aerosol state and thereby prevent the formation of an explosive dust-air mixture.

The article is devoted to the study of the problem of spontaneous combustion of energy grades of coal not only during storage, but also during transportation. As the main samples for the study, the energy grades of SS and Zh coals were selected. The main task of the scientific research was to study the rate of cooling and heating of coal depending on their thermophysical parameters and environmental parameters. To solve this problem, the authors used both the author's installations designed to study the thermophysical parameters of the spontaneous combustion process (the Ya.S.Kiselev method), and the NETZSCH STA 449 F3 Jupiter synchronous thermal analysis device, the NETZSCH Proteus Termal Analysis software package. On the basis of a complex study of the spontaneous combustion process, the authors of the article obtained the kinetic characteristics of the spontaneous heating process (activation energy and pre-exponential multiplier). Nomograms of the permissible size of coal density of different types and shapes of accumulation depending on the ambient temperature are presented, practical recommendations for the prevention (avoidance) of spontaneous combustion of coal fuel are given.

Purpose: Currently, the use of space observation systems (ESS) with spacecraft (SC), the angles of destabilization of which have signifi cant deviations from the standard values, is of particular relevance. The article offers an approach to evaluating the possible results of the use of the ESR in these conditions. Materials and methods. The article offers an original approach based on the use of methods and models of the theory of the effectiveness of space systems to assess the impact of the SPACECRAFT roll on the effectiveness of solving the problem of observing marine objects. Results. In order to solve the tasks set, the authors of the article improved the scenario-time method for evaluating the effectiveness of the use of SSC for conditions of changing the angle of roll of the SPACECRAFT. The article shows how, by implementing this improved method in simulation models of the functioning of the OSN and drawing possible scenarios for the actions of the monitoring object (МО), it is possible to evaluate the possible results of the system and plan its application in the interests of information consumers. Conclusion: The proposed improved scenario-time method for evaluating the effectiveness of the use of an ESR for conditions of changing the angle of roll of the SPACECRAFT has great prospects, since it is based on fundamental and applied results obtained so far in the theory and practice of using space systems for various purposes.

The paper is devoted to the creation of methane and dust explosion risk assessment method for coal mines for implementation of the risk-oriented approach to supervisory activities and also for solving the information support problems in managerial decisions making procedures, which aims to reducing the probability of methane and dust explosions in underground workings of coal mines. The premises for transition to the dynamic model of the risk-oriented approach are indicated. The information about dynamics of fatal injuries coefficient for underground coal mining for the last 10 years is provided. The model of expert system, based on fuzzy logic, is proposed. The model is designed for risk assessment in condition of information uncertainty in case of incompleteness or lack of reliable data about the impact of risk factors on the mine safety level. On the basis of the investigation of accidents materials in Russia in 2006-2017, the structural scheme of the expert system was created. Input parameters of the model and results of expert assessment of risk factors are described. The fuzzy logic inference knowledge base was created with using of the MATLAB Fuzzy Logic Toolbox computing environment for taking into account the influence of the complex of geological, technical and subjective factors on the risk of methane and dust explosions. The developed model allows ranking the coal mine sites according to the explosions risk levels, which was proved by processing of the initial data sample. The developed model can be integrated into multifunctional safety systems to assess the risk of various type accidents in real time.