The mine seals in coal mines with a good impact resistance and air tightness are mainly used to isolate abandoned mining areas from active workings. For one thing, it can prevent the leakage of harmful gases, such as toxic gas from abandoned areas. For another, once an underground mine explosion happens, it can effectively block the spread of the explosion between the abandoned mining areas and the active workings. Hence, it is of great significance to study the explosion-proof performance and mechanical properties of the mine seals. First of all, the effect of slotting on the stability of the seals in coal mines under explosion load was explored in this study. By numerical simulations, the mechanical response characteristics of the seals with or without cutting a slot under the explosion load were compared in detail. The results show that slotting improved the stress concentration at the contact surface of surrounding rock by transferring partial impact received by mine seals to the surrounding rocks, thus, to achieve the effect of buffering explosion impact. Besides, such effect will be enhanced with increasing cutting depth into rock, and will stabilize when the depth is 20 cm. On this basis, the mechanical properties and damage of the seals constructed by different materials (standard brick and #C40 concrete) under the explosion load were compared. It was found that once a slot was set, the maximum deformation of the concrete seal was reduced, while the maximum deformation of the brick seal increased. Since the non-deformability of the concrete seal is obviously stronger than that of the brick seal, with the impact resistance stronger than that of the brick seal, the concrete seal is more suitable for slotting. Moreover, the damage of the seals in underground coal mines under the strata ground pressure was studied; the results of which show that the damage state under the ground pressure can be divided into 3 levels, i.e. no damage, minor damage and rapid development of damage. Meanwhile, it was found that the prestressed structure formed by the ground pressure at the level of no damage can enhance the protective effect of the seals in coal mines. However, when the ground pressure was further developed, the seal itself was destroyed and the protective effect was lost. In addition, the influence of roof to floor moving convergence, a deformation parameter of the roadway, on the seals was also investigated. The results show that the ground pressure and roof-to-floor convergence act on the seals in coal mines in the same way, thus roof to floor moving convergence can replace the ground pressure to analyze other related mechanical properties of the seals in coal mines in the future researches.

The paper presents results of a parametric analysis of a hightemperature nuclear-reactor cogeneration system. The aim was to investigate the power efficiency of the system generating heat for a high-temperature technological process and electricity in a Brayton cycle and additionally in organic Rankine cycles using R236ea and R1234ze as working fluids. The results of the analyses indicate that it is possible to combine a 100 MW high-temperature gas-cooled nuclear reactor with a technological process with the demand for heat ranging from 5 to 25 MW, where the required temperature of the process heat carrier is at the level of 650°C. Calculations were performed for various pressures of R236ea at the turbine inlet. The cogeneration system maximum power efficiency in the analysed cases ranges from ~35.5% to ~45.7% and the maximum share of the organic Rankine cycle systems in electric power totals from ~26.9% to ~30.8%. If such a system is used to produce electricity instead of conventional plants, carbon dioxide emissions can be reduced by about 216.03–147.42 kt/year depending on the demand for process heat, including the reduction achieved in the organic Rankine cycle systems by about 58.01–45.39 kt/year (in Poland).

The justification for the document Study of the Conditions and Directions of the Spatial Management of a Commune created by Cracow’s Municipality Planning Office, reveals the numerous of intercommunal dysfunctions included in these documents for different communes and shows differences between Studies and Voivodeship Spatial Management Plan of Małopolska. The main purpose of the article is the discussion on the issue, showing the research methodology of intercommunal relationships analysis (conducted in the Justification) and inquiry for the solutions in Polish law system, which could resolve the problem.

The paper presents the results of optimizing the coefficient of the share of cogeneration expressed by an empirical formula dedicated to designers, which will allow to determine the optimal value of the share of cogeneration in contemporary cogeneration systems with the thermal storages feeding the district heating systems. This formula bases on the algorithm of the choice of the optimal coefficient of the share of cogeneration in district heating systems with the thermal storage, taking into account additional benefits concerning the promotion of high-efficiency cogeneration and the decrease of the cost of CO2 emission thanks to cogeneration. The approach presented in this paper may be applicable both in combined heat and power (CHP) plants with back-pressure turbines and extraction-condensing turbines.

The article describes features of Jerzy Topolski’s narrative in economic history. It focuses on four important threads and moments in his research on this field: great manor property, estimation of national income in the history of Poland, the birth of capitalism in Europe, social dependencies in the manor economy system.