In recent years, the export volumes of Russian coal to the Asia-Pacific countries have been continuously growing. Coal dust is among of the strongest air pollutants. The article describes the study of airborne particulate matter in large transport hubs of the Primorsky Krai (Russian Far East): Nakhodka city and Posyet urban-type settlement using the method of measuring the mass and quantitative concentrations of particulate matter. It is shown that the air of these areas is polluted with particulate matter with diameter below 10 microns (PM10). The absolute dominance of 0.3 μm and 0.5 μm particles was revealed in the air of both areas. According to the Russian hygienic standard, the maximum permissible concentrations of PM were exceeded only at several sampling points. However, when compared to some international standards, the content of PM exceeded maximum permissible values at 42% of sampling points in Nakhodka city and at 43% of sampling points in Posyet settlement. It is advisable to install systems for continuous environmental monitoring of air pollution with coal dust particles near coal terminals.
In the paper the authors provide the method for calculating the heat content of the molten electrode metal droplets according to the energy parameters of the power supplies for manual metal arc welding. It was established that the type of the welding power supply has a significant impact upon the temperature, mass and active surface area of the electrode droplets.
A method is described to determine geometrical dimensions of electrode metal droplets depending on short circuit duration. It provides a quantitative evaluation of the electrode metal transfer and the energy impact on metal parts being welded. It is proved that using inverter power source decreases the size of droplets transferred to the welding pool by 24% in average if compared with a diode power source. It also reduces overheating of the droplets which improves efficiency of transferring chemical elements from the electrode to the weld metal.
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