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Elaboration of stochastic models to comprehensive evaluation of occupational risks in complex dynamic systems

Bochkovskyi A. P.

Journal of Achievements in Materials and Manufacturing Engineering

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2021

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Vol. 104, nr 1

31--41

EN

Purpose: Elaborate stochastic models to comprehensive evaluation of occupational risks in “man - machine - environment” systems taking into account the random and dynamic nature of the impact on the employee of negative factors over time. Design/methodology/approach: Within study, the methods of probability theory and the theory of Markov processes - to find the limit distribution of the random process of dynamic impact on the employee of negative factors over time and obtain main rates against which the level of occupational risks within the "man - machine - environment" systems can be comprehensively evaluated; Erlang phases method, Laplace transform, difference equations theory, method of mathematical induction - to elaborate a method of analytical solution of the appropriate limit task for a system of differential equations in partial derivatives and appropriate limit conditions were used. Findings: A system of differential equations in partial derivatives and relevant limit conditions is derived, which allowed to identify the following main rates for comprehensive evaluation of occupational risks in systems "man - machine - environment": probability of excess the limit of the employee's accumulation of negative impact of the harmful production factor; probability of the employee’s injury of varying severity in a random time. An method to the solution the limit task for a system of differential equations, which allows to provide a lower bounds of the probability of a certain occupational danger occurrence was elaborated. Research limitations/implications: The elaborated approach to injury risk evaluation is designed to predict cases of non-severe injuries. At the same time, this approach allows to consider more severe cases too, but in this case the task will be more difficult. Practical implications: The use of the elaborated models allows to apply a systematic approach to the evaluation of occupational risks in enterprises and to increase the objectivity of the evaluation results by taking into account the real characteristics of the impact of negative factors on the employee over time. Originality/value: For the first time, a special subclass of Markov processes - Markov drift processes was proposed and substantiated for use to comprehensive evaluation of occupational risks in “man - machine - environment” systems.

2

Elaboration of occupational risks evaluation models considering the dynamics of impact of harmful factors

Bochkovskyi A. P.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 102, nr 2

76--85

EN

Purpose: Elaborate and substantiate stochastic models of occupational risk evaluation for application in the occupation health and safety. Design/methodology/approach: Analysis of scientific and technical literature and regulatory framework for risk evaluation in the occupation health and safety; methods of probability theory, theory of Markov processes; methods of restoration theory. Findings: A system of differential equations and limit conditions for finding the limit distribution of probabilities of a random process of occupational dangers is derived. Based on the results of solving the limit value task, expressions to determine a number of key indicators by which the level of occupational risk can be evaluated are obtained. Research limitations/implications: The proposed approach aims to evaluation the risk associated with the impact on the employee of harmful factors, but can also be used to evaluate the injury risk. But in this case the received limit value task will be much more difficult. Practical implications: The application of the proposed approach allows to increase the level of occupational safety by taking into account the stochastic characteristics of the negative factors impact on the employee during occupational risks evaluating, as well as the possibility of setting such values of controllable parameters that will allow with a certain probability to ensure not to exceed the level of impact accumulation in the employee of the consequences of these factors. Originality/value: Stochastic models of occupational risk evaluation based on the application of Markov drift processes for the modeling the hybrid nature of the negative factors impact on the employee, which occurs within the real systems "man - technical system - production environment" were elaborated and substantiated for the first time.

3

Health-aware and fault-tolerant control of an octorotor UAV system based on actuator reliability

Salazar Jean Carlo, Sanjuan Adrián, Nejjari Fatiha, Sarrate Ramon

International Journal of Applied Mathematics and Computer Science

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2020

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Vol. 30, no. 1

47--59

EN

A major goal in modern flight control systems is the need for improving reliability. This work presents a health-aware and fault-tolerant control approach for an octorotor UAV that allows distributing the control effort among the available actuators based on their health information. However, it is worth mentioning that, in the case of actuator fault occurrence, a reliability improvement can come into conflict with UAV controllability. Therefore, system reliability sensitivity is redefined and modified to prevent uncontrollable situations during the UAV’s mission. The priority given to each actuator is related to its importance in system reliability. Moreover, the proposed approach can reconfigure the controller to compensate actuator faults and improve the overall system reliability or delay maintenance tasks.

4

Postural analysis in HMI design: an extension of OCRA standard to evaluate discomfort level

Naddeo A., D’Oria C., Cappetti N., Pappalardo M.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 39, nr 1

60-70

EN

Purpose: The aim of this work consists in developing a design methodology for preventive ergonomics and comfort analyses of Human-Machine-Interface (HMI). Design/methodology/approach: Our method is based on the simulation of the main posture that a digital human model (a manikin representing, for example, a car’s driver) takes while using a machine (in this work, driving a car), in order to judge human safety and comfort during interaction with dashboard, instruments’ panel, levers and other commands. The ergonomic analyses are made using an appropriately modified OCRA (Occupational Repetitive Actions Index) protocol, in order to evaluate different involvement degrees of upper limb segments in comfort action range. Findings: The three-F principle -Human fit, form and function- is becoming the most addressed guideline for improvement and appeal-increasing of product in the current demanding global marketplace. Our work uses modern technologies and new design methods, developed by our research team, and allows to manage and optimize Human Machine Interface under “comfort” point of view. Research limitations/implications: Today, designers attempt to elaborate product development methodologies that conform itself towards best comfort performance; our work helps them to override several problems that a product development plan shows. Future developments can be made using biomechanical parameters and studies in order to better quantify and evaluate the comfort parameters. Practical implications: Using our approach and methods, comfort analysis can be made in the earliest part of the design development of a product so that designers can appreciably reduce time to market and improve and innovate comfort performances. Originality/value: First paper on this matter has been presented by one of the authors in 2008 in a World Automotive Congress; it has been the first paper on this specific matter. All over the world, new research frontier, on these topics, is going towards HMI evaluation under physical comfort and cognitive ergonomics point of view. Our paper represents, today, the newest and more specific development method, especially in automotive field of research.

5

Influence of management system on the safety level in chosen enterprise

Spilka M., Kania A.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 39, nr 1

95-102

EN

Purpose: In this paper the analysis of influence of management system on safety level in extractive industry was carried out. The effects of the occupational health and safety management system implementation were presented. The necessity of threats monitoring and preventive treatments were showed. Design/methodology/approach: In this article the essence of industrial safety was presented. The problem of occupational risk and the results of threats on the work position were talked over. Moreover, the occupational health and safety management according to PN-N-18001 standard was characterized. Findings: The analysis of enterprise functioning, developed in respect of infrastructure and occurring threats taking into consideration industrial safety after occupational health and safety management system introduced was carried out. Research limitations/implications: According to continuous improvement principle the necessity of supervise actions in direction to improvement of health and work conditions of workers exist. Practical implications: The implementation of the occupational health and safety management system brings profits as reducing of heavy and fatal accidents index. In enterprises observed minimizing of negative health effects caused by industrial accidents. Originality/value: In this paper indicated that present coal-mining needs effective system actions which should be directed on threats reducing causing industrial accidents.