The authors established the chemical and phase compositions of grain fractions of the magnesia carbon scrap disintegrated using industrial cone crushers. The investigations included chemical and XRD analyses and optical investigations. The contents of admixtures: SiO2, CaO, Fe2O3 and Al2O3 increase with the decreasing size of the scrap grain fractions, whereas the C/S ratio decreases in finer and finer fractions due to changes of the phase composition. These relations are caused by the presence of low-fusible silicate phases, characterized by their cleavage and brittleness. Such phases were mainly derived from the graphite ash containing a high silica content. The scrap after removing its finest grain fractions can be recycled and utilized for producing the magnesia-carbon refractory materials. However, the finest grain fractions may be used, e.g. as a component of gunite mixes. Many years of experience collected by the ArcelorMittal Refractories Ltd., Krakow, Poland in the field of refractory scrap utilization has also been presented.
The safe and reliable operation of pressurized water reactors (PWRs) depends on the integrity of structural material. In particular, the failure of steam generator (SG) tubes on the secondary side is one of the major concerns of operating nuclear power plants. To establish remediation techniques and manage damage, it is necessary to articulate the mechanism through which various impurities affect the SG tubes. This research aims to understand the effect of impurities (e.g., S, Pb, and Cl) on the stress corrosion cracking of Alloy 600 and 690.
In order to improve the efficiency and ensure the security of power supply used in a mine, this paper mainly studies the quasi-resonant flyback secondary power supply and analyzes its operational principles based on the requirements of soft-switching technology. In accordance with the maximum energy of a short-circuit and the request of maximum output voltage ripple, this paper calculates the spectrum value of the output filter capacitor and provides its design and procedures to determine the parameters of the main circuit of power supply. The correctness and availability of this theory are eventually validated by experiments.
2018 amendment of the act on the Polish Institute of National Remembrance that was passed by the Polish Sejm in January 2018 raised a vibrant public debate about Polish-Jewish relations. In this article, we try to trace the dynamics of this debate and assess its consequences for contemporary Polish-Jewish relations and present-day representations of the relations between Poles and Jews during the German occupation in 1939–1945. To this end, we present the analysis of social media content, data from search engines, as well as the results of two nationwide polls conducted at the beginning of 2018. These studies indicate that the debate on amendment of the Act on the Institute of National Remembrance has increased the expression of antisemitic prejudice in the media and on the internet, increased the presence of defective codes of memory, and at the same time polarized the Polish debate about the behavior of Poles during the Holocaust. The results of these analyzes are discussed in the context of earlier debates on the Polish-Jewish relations during Nazi occupation, referring to the category of “secondary antisemitism” that receives growing support in current social sciences.