Ensuring access to sustainable, affordable and clean energy sources is a top priority of the global energy agenda. It is reflected in the seventh goal of the UN Sustainable Development Agenda with the three dimensions of economic growth, social inclusion and environmental protection. The seventh goal is aimed at providing the sustainable development of energy systems whilst taking into account these dimensions. To assess the development trends of national energy systems within the framework of the global energy agenda, certain methods of quantitative measurement have acquired particular relevance. Approaches to assessing energy security mainly depend on the interpretation of the “energy security” concept. The main methods for the integrated assessment of the energy security of states are generally compiled by international organizations. An important indicator for the measurement of the sustainable development of energy systems is the Energy Trilemma Index, built within the framework of the “energy trilemma” concept. It allows quantifying the ability of states to ensure energy security, energy equity and environmental sustainability, taking into account the national context.
Special attention is paid to the analysis of the energy systems of Russia, Kazakhstan and Armenia through the Energy Trilemma Index 2022. The studied countries actively participate in the integration processes in the Eurasian and post-Soviet space. Thus, the analysis of the Energy Trilemma Index 2022 allows us to become acquainted with the main trends of the energy sector development in the Eurasian space, exploring the conjuncture of energy markets and their main challenges. The study of the energy systems of Russia, Kazakhstan and Armenia through the energy trilemma index enables the identification the methodological significance of the index for assessing the sustainable development of national energy systems. The practical relevance of the index in the formation of the state energy policy for the sustainable development of the energy systems has also been emphasized.

Modelling quasigeoid with centimetre accuracy requires taking into account irregularities of topography in the vicinity of a gravity station. i.e. the terrain correction w surveyed gravity. Accuracy of determination of the terrain correction affects quality of quasi geoid model determined. It depends on the resolution and accuracy of terrain data that usually is provided in the form of a digital terrain model DTM. Investigations were conducted with the use of the Digital Terrain Elevation Data - DTED2 model developed for Poland according to the NATO-STANAG 3809 standard, as well as global models SRTM3 and SRTM30 (The Shuttle Radar Topography Mission). Also height data from the gravity database was considered. The prism method of determination of terrain corrections was applied in majority of numerical tests. Practical method for determining the optimum radius of the integration cap considering roughness of topography as well as required accuracy of terrain corrections was developed. The effect of vertical and horizontal uncertainty of a DTM as well as its resolution on the quality of the terrain corrections was investigated. The terrain corrections obtained using a prism method were also compared with the respective ones calculated using the FIT approach. The usefulness of the available topography data for precise terrain correction computation in Poland was discussed. The results of the investigations were used to determining the strategy of computation of the terrain corrections to point gravity data in the gravity database for Poland. The "2005" terrain correction set calculated for I 078 046 gravity stations contributes to the increase of precision of gravimetric quasigeoid models developed for Poland.

The authors present a proposal for modelling the process of scraping of load units (packages) from sorting belt conveyors with the use of deflection scrapers. The continuous scraping process was subjected to discretisation. Characteristic stages of the process were distinguished, such that determine different kinematics-dynamic properties of the load. The created model makes it possible to test the scraping process, and to optimise it.

A lumped parameter type code, called HEPCAL, has been worked out in the Institute of Thermal Technology of the Silesian University of Technology for simulations of a pressurized water reactor containment transient response to a loss-of-coolant accident. The HEPCAL code has been already verified and validated against available experimental data, which in fact have been taken from separate effect tests mainly. This work is devoted to validation of the latest version of the HEPCAL code against experimental data from more complex tests. These experiments have been performed on three different test rigs (called TOSQAN,MISTRA and ThAI) and a part of them became the basis of the International Standard Problem No. 47 (ISP-47) dedicated to containment thermal-hydraulics. Selected experiments realized within the framework of the ISP-47 project have been simulated using the HEPCAL-AD code. The obtained results allowed for drawing of some important conclusions concerning heat and mass transfer models (especially steam condensation), two-phase flow model and buoyancy effects.