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  • Author: Tibor Krenický x
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Abstract

Technological progress, as well as the development of the sciences on occupational health and safety, increased safety and improved working conditions in enterprises of even the most onerous industries. To maintain the required level of safety, preventive actions are taken to identify all hazards in the workplace. In practice, many methods are used to identify hazards depending on the type of technological processes and the types of workstations analyzed. The article presents the advantages of the fault tree analysis method as a tool to support the process safety management in the enterprise. The article presents features of the fault tree analysis method as a tool for better security management in an enterprise. Cause and effect relationships between events in the fault tree schema on selected examples were examined. Indirect and direct causes of accidents and failures in the enterprise have been identified, including human errors (human factor). The use of the fault tree analysis method to support accident and failure risk assessment in an industrial plant was also analyzed.

Abstract

Numerical simulation method of the working process of a centrifugal unit contactless face impulse seal is proposed. A seal functioning physical model was created. Its operation key aspects that are not taken into account in the traditional methods of calculating contactless impulse seals are identified. A numerical simulation of seal working process based on the Reynolds equation solution for the medium vortex-free motion in the gap between moving surfaces is proposed. Hypothesis that simplify the equation’s numerical solution for the face impulse seal is formulated. The numerical solution is obtained using the boundary element method. Based on the obtained numerical solution, the distribution of the working medium pressure field in the seal gap is simulated.

Abstract

Polyurethanes are materials usable in wide spectrum of applications. This article is aimed at the properties tailoring of selected polymers by an alteration in initial materials. To achieve that goal, we proposed form the polyurethane matrix by mixing materials that have a different ratio of the initial components. Mathematical model has been developed that describes relationship of structure and strength, deformation, rheological and tribotechnical characteristics of linear block-polyurethanes based on oligoether blends. Oligoethers blend samples were obtained by injection moulding on an automatic thermoplastication machine with varying proportions of the starting components over the whole concentration range. A significant change of properties over the whole concentration range was observed and compositions with unique combination of characteristics have been determined. Obtained dependencies allow to predict the composition of the binary mixture with a tailored level of strength, deformation, rheological and tribotechnical characteristics. The obtained results are fully consistent with the practical experience of processing and exploitation of initial polyurethanes.