Sevastopol State University
Author list of organization
List of articles written by the authors of the organization
-
MATHEMATICAL MODELING IN THE SYSTEM OF STRATEGIC PLANNING OF ECONOMIC SUBJECTS IN THE TOURISM SPHERE
DescriptionThe sphere of internal tourism is one of the state priorities of the Russian Federation. The development of tourism in the Crimea will ensure the integration of the region into the Russian economy. The main instrument of using the competitive advantages of the tourist destination is Crimea - public-private partnership (PPP). The state has formed a legislative base for the use of PPP. The main role in the dynamic development of tourism business belongs to business entities. For the hospitality industry, the challenge is to build an effective management system in which strategic planning plays an important role. The analysis of the strategic planning processes at the level of economic entities in the hospitality industry revealed a number of problems, one of which is the failure to use progressive methods of strategic planning, including mathematical modeling. The purpose of the study is to determine the directions for improving the strategic planning of economic entities by developing a qualitative model of the organization's development that will allow to form an information base for making sound strategic plans. To determine the construction of a qualitative model of the development strategy of organizations in the sector under study, it is proposed to use a number of average industry indicators obtained by summarizing individual indicators: the efficiency of economic activity (Y); financial stability (X). The trend modeling (Y) indicates positive moderate dynamics, while the generalized indicator Y reaches 55.7826 in 2021. Similar results were obtained in modeling the generalized index of financial stability. Both analyzed indicators X and Y change the direction of their dynamics to the opposite - upward, starting from 2016, which indicates a favorable industry-wide situation. The results of the analysis will make it possible to increase the validity of managerial decisions when formulating strategic alternatives and choosing the optimal development strategy
-
Description
This article is devoted to solving the critical task of improving the reliability of the power systems for agricultural processing plants. The article’s material is exploratory in nature, reflected in the fact that the proposed mathematical models for the analysis of groups of high-voltage induction motors will allow to investigate various modes of symmetric groups of asynchronous motors more effectively. We present the analysis of the existing mathematical models of induction motors considering the design features of such machines that directly affect the dependence of resistance and inductance on the rotor current frequency. The assumptions taken into consideration to obtain a more accurate mathematical model of the induction motor are also formulated. The article provides a comparison of different reference frames used in the mathematical modeling of asynchronous motors. It is proved that the use of the generalized coordinate vector for mathematical modeling of asynchronous motors is the most optimal approach. The equivalent circuit of asynchronous deep-bar motor in generalized vector coordinates derived in the work is used for analysis of transient behavior as well as the steady state operation. The results of the study are suitable for transient analysis of electrical power supply systems of agricultural enterprises with large number of high-power electric motors, for example, CHP of sugar processing plants and grain elevators
-
MODELING DEEP BAR INDUCTION MOTORS FOR SUGAR FACTORY ELECTRICAL POWER SUPPLY SYSTEMS
DescriptionThe article is devoted to solving the urgent task, which is improving the accuracy of transient simulation modes of power supply systems of sugar factories. The material of the article is exploratory in nature, manifested in the fact that we have studied various mathematical models designed for the analysis of symmetric modes of deep bar induction motors. A number of the provisions of article have scientific novelty, which lies in the approach to the choice of the coordinate system for modeling deep bar induction motors. We have formulated the requirements for transient analysis method for deep bar induction motor. We have developed the mathematical models of high-voltage induction motors in different coordinate systems for the analysis of steady-state and transient modes of operation. Based on double-circuit rotor model of induction motor, an analytical expression for the frequency characteristic of the deep bar induction motor is obtained. As an example, we have calculated and presented real and imaginary parts of the frequency characteristic of the induction motor type 2АЗМ-2000 with slip s = 1. The mathematical models of induction motors allow using mathematical apparatus more efficiently to explore different symmetrical modes of engines. The study proposed to use transients in the power supply systems of sugar factories for the analysis. The authors suggest an approach to modeling, which can also be useful for modeling induction generators
-
OBTAINING OF FREQUENCY CHARACTERISTICS FOR INDUCTION MOTORS USING THE RESULTS OF THE EXPERIMENT
DescriptionThe article is devoted to the solution of the urgent task, which is to increase the reliability of the power supply systems of enterprises for processing agricultural products. The material of the article has a research character, which consists in the fact that the obtained expressions for the frequency characteristics of high-voltage induction motors allow us to investigate the symmetric modes of their operation by means of a more efficient and simple apparatus. A number of provisions of the article have a scientific novelty, which consists in obtaining frequency characteristics for induction motors as a result of the experiment. A convenient procedure for obtaining the frequency response of an induction motor based on the results of an experiment using the mathematical model of an induction motor in the coordinates of the generalized vector and the Fourier transform has been developed. As an example, oscillograms of the stator current of an induction motor of the A-12-52-4 type are given for the initial stage of the start-up. For the stator current of this induction motor, a transition is made from the phase coordinate system to the coordinates of the generalized vector. The dependences of the stator current on the D and Q axes on time are constructed. The real and imaginary parts of the frequency characteristic of the engine are calculated for sliding s = 1, the calculations are illustrated by the corresponding graphical characteristics. The results of the study are proposed to be used for the calculation of transients in power supply systems for enterprises engaged in the processing of agricultural products