Kryvyi Rih National University

The object of research is the processes of electromagnetic transformation in powerful asynchronous electric drives during controlled start-up and their impact on the quality of electricity in the power supply network. Distribution networks of industrial enterprises are considered, which have significant dynamic loads during the start-up of powerful machines. The problem to which the research is aimed is to ensure proper quality of electricity in distribution networks of industrial enterprises when performing controlled start-up of powerful asynchronous electric drives from soft starters based on a thyristor voltage regulator. Quantitative indicators of the influence of starting devices on the parameters of electricity quality were calculated using computer modeling in the MATLAB/Simulink environment. Soft start using a thyristor regulator, although it limits the starting current, has a negative impact on the quality of electricity in the distribution network. Reactive power consumption increases, which causes a voltage drop. For the case of starting an asynchronous motor with a capacity of 3500 kW in the network of a sintering factory, it was found that direct start causes a voltage drop of about 350 V. Harmonic voltage distortions with a distortion factor of up to 6% also appear. Power active filters allow to improve the quality of electricity by introducing antiphase currents, which is proven by the application of theoretical methods of electrical engineering. The results obtained are applicable in the design of electric drive systems of powerful mechanisms during the modernization of the power supply of industrial enterprises, in the calculation of reactive power compensation means and in the development of energy quality standards. This will significantly contribute to increasing the reliability of technological equipment, reducing energy losses, and increasing the service life of electrical equipment at the enterprise.

The article provides a comprehensive scientific justification for the need for a methodological synthesis of the philosophy of public administration and the tools of the project approach in the system of organizing scientific activity. The relevance of the study is due to the urgent need to overcome bureaucratic formalism in science management and transition to a model focused on obtaining specific socially significant results. The axiological and theological principles of the modern paradigm of public governance are revealed, within which scientific knowledge is interpreted as a fundamental public good and a strategic resource of the state. The transformation of the role of the state from a strict controller to a strategic partner, providing an ethical framework and resource support for innovative research, is analyzed. It is proven that the project approach in this context acts as a basic technology that ensures the discreteness, manageability and effectiveness of the scientific process. Special attention is paid to risk management and resource allocation mechanisms, which allows adapting the rigid logic of management to the nonlinear nature of scientific creativity. A three-level integrative management model is proposed and detailed, combining the strategic-axiological, methodological-convergent and technological-operational levels. This model provides an effective decomposition of state strategic "missions" into specific scientific projects with clearly defined success indicators. The practical experience of the functioning of modern institutional instruments, such as DARPA (USA) and the Ukrainian DefenseTech cluster (Brave1), is analyzed, which confirms the viability of the proposed synthesis in conditions of crisis challenges and martial law. It is substantiated that the implementation of the synthesized model creates a synergistic effect for the state (due to the transparency of costs), the scientific community (due to the reduction of administrative pressure and clarity of criteria) and society as a whole. It is determined that the final result of such methodological convergence is the construction of an effective system of management decision-making based on scientific evidence, which is extremely important for the sustainable development of national security and the country's innovative potential.

In the context of rapid growth in the tourism industry and increasing attention to sustainability issues, the Global Sustainable Tourism Council (GSTC) standards have become an essential benchmark for the hospitality sector worldwide. As Ukraine moves toward integration into the global tourism market, adopting the Global Sustainable Tourism Council standards is crucial for maintaining environmental, social, and economic sustainability within the industry. The subject of the study is the Global Sustainable Tourism Council standards and indicators of sustainable tourism and hospitality development. The purpose of the article is to analyze international standards and indicators of sustainable tourism and hospitality development, particularly the criteria of the Global Sustainable Tourism Council, and to determine their significance for the Ukrainian tourism and hospitality industry development. The objectives of the study are: to analyze the structure and content of international standards and indicators for sustainable tourism and hospitality development, with a focus on the Global Sustainable Tourism Council criteria; to determine the significance and practical implications of applying GSTC standards for enhancing the competitiveness and sustainability of the Ukrainian tourism and hospitality industry. Research methods: generalization and systematization (to identify groups of criteria and indicators of sustainable development in the tourism and hospitality industry); systemic and comprehensive analysis (to determine the importance of applying global sustainable tourism council standards for the Ukrainian tourism and hospitality industry development); graphical method (for visual representation of theoretical material). Results. A comprehensive review of the standards and recommended indicators of the Global Sustainable Tourism Council (GSTC) for tourism and hospitality has been carried out, with a focus on their structure and key thematic areas. A detailed analysis of the four main blocks of GSTC criteria – effective sustainable management, socio-economic benefits, cultural heritage preservation, and environmental protection – has been conducted. The review demonstrates how these standards align with the United Nations Sustainable Development Goals (SDGs) and serve as a universal basis for assessing the sustainability of tourism enterprises and destinations. The necessity of applying GSTC criteria for the Ukrainian tourism and hospitality industry has been substantiated, emphasizing their role in enhancing competitiveness and sustainability. The strategic importance of these standards for post-crisis recovery, shaping a positive image of Ukraine as a sustainable tourism destination, and ensuring long-term resilience through responsible practices has been highlighted.

The article considers the features of the distribution, morphology and mineral associations of dispersed gold in modern coastal-marine, deltaic and alluvial deposits of Southern Ukraine. The results of comprehensive studies of river valley and shelf zone deposits are analyzed, as well as technological approaches to the extraction of flaky and dispersed gold. The prospects of exploration of such deposits and the introduction of innovative methods for their development are substantiated.

Purpose. Extreme situations at industrial facilities often lead to fires, in particular, fires occur in the event of drone attacks on oil storage facilities. In such cases, a significant amount of chemically hazardous substances (fuel combustion products) are released into the air, posing a risk of thermal injury to workers. Various means and structures are used to reduce the risk of thermal injury. When designing protective structures, it is necessary to determine in advance their effectiveness and the time of possible destruction. This requires the development and use of specialized mathematical models. This work is devoted to the development of numerical models that allow predicting thermal fields at an industrial site in case of fire and assessing the risk of destruction of a protective wall (barrier). Methodology. To numerically solve aerodynamic problems (determining the wind speed field), calculate areas of thermal pollution of the air at an industrial site, and determine the dynamics of temperature changes inside a protective barrier (wall), we use fundamental models of continuum mechanics. Finite difference schemes are used for the numerical solution of simulation equations. Findings. A computer program has been developed that makes it possible to solve a «coupled» problem of determining the zone of thermal pollution of air at an industrial site and the dynamics of heating of a protective barrier (wall). Using the proposed numerical model and computer program, it is possible to solve the problem of thermal conductivity and heat transfer in real time. Originality. A fast-calculation numerical model is presented for estimating the time of destruction of a protective barrier at an industrial site where a fire occurs. The analysis of thermal fields at an industrial site and inside the protective barrier was carried out by numerical integration of a multivariable heat transfer and heat conduction equation. The aerodynamics problem was solved based on a potential motion model. These numerical models require little computer time for practical implementation. Practical value. The proposed numerical models can be used for a preliminary assessment of the temperature field inside the protective barrier to determine its effectiveness in terms of protecting areas from thermal pollution at an industrial site. This info can be useful at the preliminary design stage of protective structures.

Purpose of the Study. The study aims to investigate various approaches to mitigating the impact of renewable energy sources on the stability of the power system and to determine the optimal combination of conventional and renewable energy sources to ensure stable and reliable energy supply. The effectiveness of different approaches to minimizing the impact of renewable energy on grid stability is evaluated. Materials and Methods. Methods of eigenvalue analysis and transient process modeling were used. Correlation and regression analysis methods were used to assess the impact of renewable energy sources (RES) on the stability of the energy system. Data from the system operator «Ukrenergo» were used, including power system load schedules (hourly, daily, seasonal). Data from the Ukrainian Hydrometeorological Center for the years 2023–2024 were used to model RES generation: data on solar radiation (hourly, daily) and wind speed (hourly, daily). Technical specifications of solar panels and wind turbines installed in Ukraine were also used. The QGIS software was utilized for geoinformation analysis. The study employed artificial neural network theory, optimization methods based on linear programming and logical production rules, as well as methods for assessing and regulating steady-state operating conditions of the system, taking into account energy storage devices. Results. The scientific novelty lies in the development of an innovative method for assessing the reduction of the impact of renewable energy sources on power system stability. The feasibility of using artificial neural networks to forecast wind and solar power generation was demonstrated, as well as the optimization of the model structure and parameters to improve forecasting accuracy. The optimal combination of conventional and renewable energy sources was determined to ensure stable and reliable operation of the power system. Practical Significance. Based on experimental and theoretical research, specific recommendations and solutions are provided aimed at ensuring the stability of the power system during the integration of renewable energy sources, including optimization of management, use of new technologies, and infrastructure development

Purpose. The work is aimed at developing a mathematical model that allows to quickly calculate the area of chemical air pollution during the emission of hazardous substances from solid waste landfills. The mathematical model takes into account meteorological parameters, geometric shape of the landfill, intensity of emission of hazardous substances from the landfill. Methodology. The two-dimensional equation of convective diffusion transfer of a conservative impurity from the atmosphere is used to analyze the intensity and size of chemical air pollution during the emission of hazardous substances from the landfill. A difference scheme of splitting is used to numerically solve the equation of convective-diffusive transfer of an impurity. The emission of hazardous substances from the landfill is modeled using the Dirac delta function. Findings. The developed mathematical model takes into account the main physical factors that affect the process of dispersion of hazardous substances from the landfill. On the basis of the developed numerical model, a computational experiment was conducted to assess the impact of the landfill on the environment. Originality. On the basis of the developed numerical model, a computer code was developed that allows predicting chemical pollution of the atmospheric wind and the underlying surface in the event of emission of hazardous substances from the surface of a solid waste landfill. The developed model and computer code make it possible to quickly assess the extent and intensity of environmental pollution from landfills, which is important when selecting sites for new or reconstructed landfills. Practical value. The software implementation of the developed numerical model was carried out, and a computational experiment was conducted to illustrate the effectiveness of using the model to solve applied problems related to the impact of landfills on the environment. The results of the numerical experiment are presented.

Abstract This research examines the behavior of long concrete-filled steel tubular elements under load, focusing on their deformation and failure mechanisms. The study employs mathematical modeling and laboratory tests to analyze concrete-filled steel tubes (CFST) and hollow pipes of 1600 mm length. The experiments introduce eccentric loading conditions with varying eccentricities of 0, 10, and 20 mm to simulate realistic scenarios. Mechanical properties of the steel and concrete are assessed through separate tests on short pipes and concrete prisms. Mathematical modeling using ANSYS software incorporates the Drucker-Prager model for concrete and bilinear isotropic hardening for steel, with frictional contact between materials. Three models are established: fully loaded CFST, hollow pipes, and CFST loaded only through the concrete core. The study assesses longitudinal and transverse deformations and stress distribution, revealing significant differences dependent on eccentric loading. Results indicate a strong correlation between model predictions and experimental data, validating the methodological approach. The research offers insights into stress concentration areas and interaction between concrete and steel, providing a basis for optimizing the design of tubular concrete structures under diverse loading conditions.

The study aims to develop critical thinking in the context of global warming, analyze existing approaches to solving this problem, and propose alternative methods of combating climate change. Materials and methods: Scientific literature was analyzed, including IPCC reports and studies on atmospheric physics and climatology. Theoretical research methods included comparative analysis, mathematical calculations, and a systems approach to assessing climate change. Calculations were made on the efficiency of mirrors in reflecting solar energy with an area ratio of 1:10,000. Results: It is revealed that the existing theory about the dominant influence of CO₂ on global warming requires critical rethinking. It is established that the content of water vapor in the atmosphere exceeds the content of CO₂ by 100 times. An asymmetric method of combating global warming through mirrors is proposed, demonstrating high potential efficiency. A comparative analysis of three main approaches to solving the problem is carried out: "space umbrella", installation of distributed mirrors, and achieving "carbon neutrality". Conclusions: A comprehensive approach to solving the problem of global warming is needed, including traditional methods of combating CO₂ emissions and innovative solutions. Mirrors are a promising, cost-effective, and reversible method of fighting global warming. Developing critical thinking is key in finding practical solutions to the climate crisis.