https://sci.ldubgd.edu.ua/jspui/handle/123456789/15859 2026-04-06T08:05:24Z https://sci.ldubgd.edu.ua/jspui/handle/123456789/15867 Title: Distribution of Heavy Metals in the Coal Mine Waste Dumps Based on Statistical Analysis Authors: Menshykova, Olga; Vasyl, Popovych; Voloshchyshyn, Andriy; Yaroslav, Genyk; Мykhaylo, Petlovanyi; Bogdan, Ilkiv Abstract: At the UN Climate Change Conference in Glasgow in autumn 2021 (COP26), world leaders and participants decided to phase out coal energy and gradually replace fossil fuels. At COP26, Ukraine has committed to shutting down state-owned coal-fired power plants by 2035, reducing methane emissions by 30% by 2030 and halting deforestation. The waste dumps are also a detrimental factor in coal mining. The determination of the heavy metals content in the waste dumps of coal mines is a topical issue today, as the results of such studies are part of the monitoring of the environmental safety of mining regions. This scientific article considers the results of research on the heavy metals content in the waste dumps and their distribution in one of the largest coal mines in the Lviv-Volyn coal basin –‘Chervonohradska’ (Ukraine). 2.9 million m3 of rock have accumulated in the dump since 1971. Every year, 40,000 m3 of fresh rock is dumped. Samples were taken uniformly from all sides of the dump in places with no vegetation cover. Note that exceeding the maximum allowable concentrations of the studied heavy metals is observed in all areas except for Zn. Statistical analysis of the results of semi-quantitative spectral studies of waste dumps rockat the Chervonohradska mine site was performed using the Statistica 8 applied statistics package. 2023-01-01T00:00:00Z https://sci.ldubgd.edu.ua/jspui/handle/123456789/15866 Title: Determination of frequency of transverse oscillations of an elasticly fixed disc of a circular saw Authors: Menshykova, Оlha; Dziuba, Lidiia; Chmyr, Oksana; Lishchynska, Khrystyna Abstract: The object of the study is a circular saw blade. An annular plate of constant thickness with a free outer contour and a fixed inner contour was taken as the calculation scheme of the saw blade. The real conditions for fixing the internal circuit correspond to the elastic fixing of the saw blade with clamping flanges on the shaft of the machine. For the accepted calculation scheme of the circular saw, the dynamic model was a fourth-order nonlinear differential equation of the transverse oscillations of the annular plate with the corresponding boundary conditions. The rotation of the circular saw was taken into account in the dynamic model due to the radial force in the middle surface of the ring plate. This force arises as a result of the action of centrifugal forces during the rotation of the saw blade. The solution to the fourth-order nonlinear differential equation was constructed using the Bubnov-Galyorkin numerical method. 2023-01-01T00:00:00Z