This article considers the criteria for the existence of established modes of power systems. Nonlinear nodal equations of steady-state modes are presented, which have many solutions or do not have any physically realizable solutions. Criteria for the existence of solutions are given based on derivatives of power losses depending on the parameters of the power system modes. Equivalent circuit of the electrical system was performed using the South-Western MEN (MAIN ELECTRIC NETWORKS). The paper highlights the results of calculations of steady-state modes of the electrical system at weighted values of node 12. The maximum normal modes of electrical systems for the power of nodes was determined by the criteria are set ∂ Δ P c ∂ Π i = ∞ .

When studying the topic, the author analyzes the implementation of reforms and their impact on the development of the agricultural sector of the Republic of Uzbekistan. Special attention is paid to the pandemic crisis that has affected all spheres of the economy and the life of the population. The importance of the actions taken by the state in relation to the improvement of the agricultural sector, not only through the production of agricultural raw materials, but also in other ways, is revealed. One of these ways is the production of products that can compete on the world market, the production of semi-finished products, and others. Methods of analysis, synthesis, grouping, observation, and deduction were used in the study of the material. Using these methods, the authors were able to come to a better conclusion, and make suitable conclusions and suggestions. In conclusion, the ways to improve the efficiency of agricultural production, through the introduction of resource-saving technologies, innovative technologies, and especially the removal of state attention to the agricultural sector, are revealed. The article also focuses on the state of agriculture during and after the pandemic, and compares it with other countries of the world. The authors made proposals that are most suitable for the development of agriculture, ensuring food security and independence of the population.

The article presents an analysis of the dynamic response of an underground main pipeline under the action of a longitudinal wave, propagating in soil along the pipe. It is assumed that the elastic pipe has a finite length. A linear viscoelastic model of the "pipe-soil" system interaction is considered. The influence of a pulse in the form of a triangle on the deformed state of an underground main pipeline is investigated. The article presents a comparative analysis of the results obtained for some values of the coefficients of elastic and viscous interaction, the propagation velocity, and the duration of the pulse. In the case of elastic interaction of the "pipe-soil" system, the reflection of the wave propagating in the underground pipeline on the boundaries of the pipeline when it coincides with the wave propagating in the soil leads to an increase in the maximum deformation of the underground pipeline, the value of deformation can double. The viscosity coefficient of interaction at the pipe-soil system contact leads to the wave front attenuation in the underground pipeline. For soils with the coefficient of viscous interaction higher than 100 kN∙s/m2, this leads to complete attenuation of the bursts at the wave front in the pipeline. The influence of the wave propagation in soil on the deformation values at the wave front was also studied.

No abstract

The fishing industry has a special role in the development of the agricultural economy. Fish farming in cages is currently very important and is a promising and economically profitable form of growing marketable fish. The fishing industry has many advantages, such as beneficial effects on the health of the population, on the environment, and on the world’s economy. Activities carried out in the fish farming industry provide ample opportunities. These activities are the organization of fish farming clusters, the use of intensive methods and resource-saving technologies, the transportation of compound feed and mineral fertilizers to fish farms. Intensive fish farming can reduce the cost of fish and maintain the existence of many types of commercial fish.