When mining coal from the working face, the main roof withstands the overlying strata. The main roof’s first weighting and periodic weighting may cause accidents, such as crushing the working face hydraulic supports. A mechanical model of the main roof was constructed, and the contributing factors of first and periodic weights on the main roof were examined in order to prevent such accidents. The thickness of the main roof was found as the most contributory factor to the main roof’s stability. Therefore, a new directional roof crack (DRC) technique is proposed, which produces directional cracks in the main roof through directional blasting and makes part of it collapse in advance so as to reduce the thickness and relieve the first and periodic weighting. To verify the effectiveness of DRC, the mechanism of DRC was analysed. A mechanical model of the hydraulic support was constructed, and the DRC techniques were tested on-site. Field experiments with a complete set of monitoring schemes showed that, with DRC technology, the roof periodic weighting interval decreased by 35.36%, and the hydraulic support pressure decreased by 17.56%. The theoretical analysis was consistent with the measured results. Therefore, the DRC technology is feasible and effective to ensure mining safety at the working face.

Increasing of the efficiency of convective cooling of the inner surface of a short duct by changing its geometry was studied by the use of electrochemical limiting current technique (ELDCT). The duct consisted of seven identical, cylindrical segments. The changes of the duct geometry were obtained by mutual displacement of neighbouring segments, towards the radial direction. Mean values of the mass transfer coefficient for each segment and friction losses for the whole channel were measured for Reynolds numbers spanning the range 7700–35300 at the five values of displacement parameter. The results were used for estimation of cooling efficiency. Recommended values of displacement were determined to point the favourable conditions of heat/mass transfer in the duct. The results may be used, e.g. in the design of heat exchangers and channels for cooling of turbine blades and electronic equipment.

The author supports the claim that attempts to formulate a universal definition of the term “populism” are not worthwhile, because the sense of the term is usually determined by a specific social context. Understanding the utopian nature of populism provides a better understanding of the utopian nature of democracy and allows for a humble departure from dreams of a perfect social order, because, as has been shown in numerous survey studies, the contemporary shift of social mood, attitudes, and opinions toward some version of populism is a relatively simple consequence of the deficiencies of democracy in its neoliberal version.

This study examines whether the lowering interest-rate environment in CEE countries since the early 2000’s increased bank risk-taking behaviour. We employ 6,979 annual observations from the Bankscope database over the period 1997‒2011 and find a positive relationship between bank risk-taking, measured by risk assets, and interest rates. On the contrary, there is a negative relationsh ipbetween non-performing loans and interest rates. These results are robust across a number of different specifications that account,inter alia, for the potential endogeneity of interest rates and/or the dynamics of bank risk. Moreover, we provide evidence that these findings are mainly driven by the banking sector of the Russian Federation rather than that of the rest CEE countries.