Computer Simulation Model Research Articles

A dimer between monomers and hexamers-Oligomeric variations in glucosamine-6-phosphate deaminase family.

In bacteria that live in hosts whose terminal sugar is a sialic acid, Glucosamine-6-phosphate deaminase (NagB) catalyzes the last step in converting sialic acid into Fructose-6-phosphate. These bacteria then use the Fructose-6-phosphate as an energy source. The enzyme NagB exists as a hexamer in Gram-negative bacteria and is allosterically regulated. In Gram-positive bacteria, it exists as a monomer and lacks allosteric regulation. Our identification of a dimeric Gram-negative bacterial NagB motivated us to characterize the structural basis of two closely related oligomeric forms. We report here the crystal structures of NagB from two Gram-negative pathogens, Haemophilus influenzae (Hi) and Pasturella multocida (Pm). The Hi-NagB is active as a hexamer, while Pm-NagB is active as a dimer. Both Hi-NagB and Pm-NagB contain the C-terminal helix implicated as essential for hexamer formation. The hexamer is described as a dimer of trimers. In the Pm-NagB dimer, the dimeric interface is conserved. The conservation of the dimer interface suggests that the three possible oligomeric forms of NagB are a monomer, a dimer, and a trimer of dimers. Computational modeling and MD simulations indicate that the residues at the trimeric interface have less stabilizing energy of oligomer formation than those in the dimer interface. We propose that Pm-NagB is the evolutionary link between the monomer and the hexamer forms.

Analysis of models of the mathematical theory of epidemics and recommendations on the use of deterministic and stochastic models

The model of the epidemic/epizootic process, in principle, should reflect the interaction of all its components: the source of the causative agent of infection, the mechanism of its transmission and susceptible individuals. The purpose of the article is to analyze models of the mathematical theory of epidemics (MTE) and provide recommendations on the areas of use of deterministic and stochastic models of MTE. Depending on the research objectives, relatively simple deterministic, stochastic models or more complex computer simulation models are used. Since each stochastic model of the mathematical theory of epidemics/epizootics has its deterministic counterpart, it is of interest to analyze the errors associated with ignoring the stochastic essence of the epidemic/epizootic process using deterministic models in various situations. As an example for error analysis, a widely used general stochastic model was chosen, the deterministic analogue of which is the Kermak model (W.O. Kermak) and Mc Kendrick (A.G. Mc Kendrik) [6]. The article discusses the principles of constructing deterministic and stochastic models of the mathematical theory of epidemics/epizootics (MTE). A comparative study of the results of the use of deterministic and stochastic models using simulation modeling is carried out. Recommendations on the areas of application of deterministic and stochastic models are given. The results of the conducted studies have shown that the choice between deterministic and stochastic models is determined by the population size, the stage of epidemic development, a set of parameters and requirements for the accuracy of mathematical modeling. It is concluded that mathematical modeling systems are designed to obtain a quantitative forecast of the development of the epidemic / epizootic process in order to assess the effectiveness of antiepidemic / antiepizootic measures, to analyze the risk and assess possible economic damage. The possibilities of predictive or retrospective modeling of the spread of infectious diseases are shown.

ІМІТАЦІЙНА КОМП'ЮТЕРНА МОДЕЛЬ ПРОЦЕСІВ РОЗПОВСЮДЖЕННЯ СИГНАЛІВ У КОАКСІАЛЬНОМУ КАБЕЛІ

Background. The paper studies processes of signal propagation in a coaxial cable as a type of artificial long lines. Utilization of analytical methods as well as natural experiments for analyzing these processes is rather difficult and not sufficiently descriptive. The aim of the paper is to develop a simulation computer model of coaxial cable represented as an artificial long line and to use this model for studying processes in it. Main attention is paid to clarify impact of irregularities in the line and matched signal transmission from the source to the load with minimal losses. Methods. Methods of computer simulation as well as complex systems analysis are used. Results. To achieve the set goal, the paper solves the tasks of a coaxial cable equivalent circuit design as an artificial long line, which includes signal source with a certain internal impedance, the line itself with a possibility to vary its parameters and the load; representation of the processes in the developed line with the help of Ohm’s and Kirchhoff’s laws in terms of differential equations of continuous time; transition from the system of differential equations to the one of difference in order to use them for computer simulation; design of a computer simulation model on the base of the obtained system of difference equations; and trial of the computer simulation model in the scenario of signal propagation in the long line with irregularities. Computer simulation results that are obtained in the paper completely correspond to the theoretical notions related to the processes in long lines in different modes of their operation. The results have allowed one to assess numerically and qualitatively, and most impotently descriptively, impact of irregularities in the line on the optimal signal transmission in it. Сonclusions. Developed computer simulation model of a coaxial cable as an artificial long line can be used for tuition processes at universities and for design and modernization of these devices. Keywords: simulation computer model, coaxial cable, artificial long line, line irregularities, matched signal transmission

Визначення оптимальної точки приєднання сонячної електростанції до електричної мережі методом комп’ютерного імітаційного моделювання

The purpose of this study is to minimize the negative impact of the solar power plant on the value of the steady voltage deviation and the level of electricity losses by determining the optimal place for its connection to the distribution network. Currently, quite a large number of methods of optimal placement of renewable sources of electricity in electrical networks have been developed. However, most of them either do not fully take into account the multifunctional influence of renewable energy sources on the parameters of the electric network regime, or are quite difficult to use. In order to solve the problem of optimal placement of renewable sources of electricity in electric networks, it is proposed to use the method of computer simulation modeling. The essence of this method is to determine the optimal place for connecting a renewable energy source to the electrical network based on the analysis of the results of computer simulation modeling of network mode parameters. This approach is the most acceptable in the case of connecting a solar power plant of average power to the electrical network of an industrial enterprise. The developed computer simulation model of a distribution electric network with a solar power plant allows for the research of network mode parameters, including the determination of the level of active power loss in network elements and the level of steady voltage deviation. The specified computer simulation models of the distribution electric network with a solar power plant made it possible to determine the optimal place for connecting the solar power plant based on the values of power losses in the elements of the electric network at the level of the established voltage deviation. The results of computer modeling of an electrical network with a solar power plant confirmed the need to take into account not only the values of the established voltage deviation, but also the amount of electrical energy losses in the network elements in the process of choosing a place to install a solar power plant. The results of the research can be used in solving the problems of determining the place of connection of a medium-power solar power plant to the electrical network of an industrial enterprise.

Оптимізація параметрів мікроклімату в навчальних закладах з системами локальної рекуперації повітря

The aim is to develop an automatic local air recovery system to ensure thermal comfort and the normative composition of the air environment in educational institution premises. Improving the efficiency of local air recovery systems while maintaining optimal microclimate parameters is possible through the enhancement of automatic control systems for local recovery devices. An automatic air local recovery control system has been developed, which guarantees optimal microclimate parameters in educational institution premises. Computer simulation modeling has been applied to control the microclimate system based on temperature and CO2 concentration. The advantages of the proposed system have been identified, which reduced the duration of exceeding the maximum allowable level of CO2 concentration by 49.5% and decreased the CO2 concentration by 13.1% within the specified temperature limits.

Designing a Computer Simulation Model to Study the Failure Mechanism in Rotating Shaft

The phenomenon of the failure of rotating mechanical structures is considered one of the dangerous phenomena that researchers are trying to study to find effective ways to avoid it. Many mathematical models describing the mechanism of crack formation in structures and the occurrence of failure in them have been adopted. In this paper, a computer simulation model of the failure mechanism in the intermediate conduction shaft of the ship's propeller (oil shuttle tanker) was designed based on the mathematical model that describes the stages of failure according to the number of revolutions that the shaft bears and the dimensions of fatigue cracks in it. In the beginning, a detailed mathematical model of the crack propagation mechanism was deduced as an initial stage, through which the differential equations that express the failure of the shaft were described. In the second stage, numerical simulations were implemented using the Euler and Rung-Kutta numerical methods used in solving ordinary differential equations. Also, for both methods using the Matlab language to reach the results and accurate graphs and analyze them. In this way it is possible to predict the number of cycles that the column will bear before the collapse, and this will reduce the occurrence of sudden collapses and save time, effort, and costs.

Theoretical reasons for rapid heating of vegetable oils by microwaves

Water and high-moisture foods are readily heated in microwaves due to their relatively high dielectric loss factors. Vegetable oil, on the other hand, has a much smaller loss factor (about 1/100th that of water), and is generally believed to be unsuitable for microwave heating. In this study, we conducted experiments to compare heating rates between vegetable oil and pure water in a 2450 MHz microwave oven. We found that the vegetable oil samples were heated rapidly in microwaves, and even faster (1.4–2.0 times) than the water samples. To provide a theoretical explanation, we developed a 3-D computer simulation model. The simulation revealed an approximately 10-fold stronger electric field in oil compared to water, resulting in a similar amount of microwave power being absorbed by the oil and water samples. As the absorbed microwave power was converted into thermal energy, the oil samples were heated faster due to their smaller specific heat (1/2 that of water). But we also found that when the dimensions of oil are smaller than half the microwave wavelength, oil is heated slower than water due to the absence of hot spot areas. This study provides a theoretical explanation for microwave heating of vegetable oils and demonstrates opportunities for utilizing microwave energy to electrify industrial heating of vegetable oils.

Automation of warehouse resource planning process by using a cloud demand forecasting tool

Purpose: Research paper is an extension of the concept connected with demand forecasting function acquisition by logistics operators in the whole distribution network (concept is considered among others in the following papers: (Kmiecik, 2021a, 2021b, 2020). The concept of centralized forecasting assumes that a logistics operator, whose attributes coincide with the features selected through analysis of forecasting-able entities in the distribution networks and flagship enterprises, is able to take over the forecasting function for the whole distribution network. Paper, which is based on the mentioned concept, shows one of the first stages of its implementation. This stage is the implementation of the forecasting tool in the logistics operator's actions to support his operational activities. Currently, the logistics operator doesn't conduct the forecasting activity, but there are attempts aimed at implementation of forecasting tool and increasing the offered services' added value level. Operational activity, which will be first to be supported, is the process of planning the warehouse resources. Mentioned resources concern the human and internal transportation resources, which are needed for fulfilling the processes connected with SKU (Stock Keeping Units) releasing from the warehouse. The main paper purpose to examine the concept the of automated cloud-based resource planning process at the selected 3PL entity which provides logistics services to wide range of manufacturers in the distribution network using the computer simulation model with comparison with the current resource planning process. Design/methodology/approach: Following research paper based on analysis the survey results and analyzing the simulation results. In the survey were tested the warehouse managers which are responsible for resource planning process. The analysis provides the general requirements of managers about resource planning process supported by automated cloud-based demand forecasting solution and information about expected forecasting tool accuracy. In the paper there were also created two simulation models based on BPMN 2.0 standard. First model reflects the current shape of resource planning process and was created to compare to the second, improved model. Improved model includes the examining of automated cloud-based resource planning solution. Findings: The main expectations of 3PL operational managers about usage the demand forecasting tool is to support of warehouse resource planning. They also state that the expected accuracy of such a tool is the weekly MAPE not greater than 5%. The main benefits of proposed solution are the time decreasing, increasing the level of automation, showing the main areas when the agile point of view should be implemented and show the perspective of resource possibility of usage in the different activities (beside the resource planning process). Originality/value: Automation and fully cloud integration will allow to reduce the process time more than 60% (in total and in average one process time). There are also some disadvantages of proposed solution which could be reduced by using other trends connected with Industry 4.0 development and by developing the collaborative strategies of the particular nodes of distribution networks. Keywords: logistics operator; distribution network; warehouse management; demand forecasting; BPMN 2.0 model. Category of the paper: research paper.

3D Computer Vision-based Production and Simulation Modeling Technologies, Geolocation Data Mining and Tracking, and Cognitive Mapping and Navigation Tools in the Industrial Metaverse

3D Computer Vision-based Production and Simulation Modeling Technologies, Geolocation Data Mining and Tracking, and Cognitive Mapping and Navigation Tools in the Industrial Metaverse

ОПРЕДЕЛЕНИЕ ДИАГНОСТИЧЕСКОГО СИГНАЛА ДЛЯ МОНИТОРИНГА СИНХРОННЫХ ДВИГАТЕЛЕЙ С ПОСТОЯННЫМИ МАГНИТАМИ

Relevance Nowadays, it is possible to achieve a significant increase in the technical and economic indicators of enterprises by improving the reliability of electrical and mechanical equipment. In this case, the time between current and overhaul repairs is increased and operating costs and, together with them, material and other resources are significantly reduced. Metallurgical production is the most expensive in terms of electrical consumption and a significant number of electric drives are concentrated there. For more than a hundred years, asynchronous electric machines have occupied key positions in regulated AC electric drives. Along with them, new types of electric machines have been actively developed in recent decades, which structurally in the active part do not contain windings on the rotor, the rotor is asymmetrical in magnetic relation, the stator can have one or two windings. Such machines include synchronous reactive and inductor electromechanical converters. All studies are of a private nature and do not cover the whole class of electric machines as a whole. There are no unified analytical dependencies for electromagnetic torque, active and reactive powers, power factor, methods of engineering calculations of machines, optimization methods, unified approaches to the synthesis of control actions on stator windings, calculation of losses, the peculiarities of synthesis of such machines for specific production mechanisms are not considered, taking into account the nature of load and speed diagrams and modes of operation in an extended range of speeds and load torques. In connection with the above-mentioned, a comprehensive study of permanent magnet synchronous motor (PMSM) is relevant, and there is a need to determine the diagnostic signs of faults both incipient and manifested. Aim of research The article is devoted to the issues of obtaining diagnostic information in the generator mode of PMSM. It is shown that the generator mode is an effective mode for obtaining a diagnostic signal, allowing to fully implement the methods of mathematical analysis of signals, without introducing errors in the form of spectral components from the work of converters. Research methods The methods of theoretical and experimental research were applied in the work. To conduct theoretical studies used software packages Excel and MathCad; software package MatLab for wavelet analysis and Fourier analysis; software package Elcut to develop a computer model and simulation modeling; the basics of wavelet theory. Results The generator mode is an effective mode of obtaining the diagnostic signal, which allows to fully implement the methods of mathematical analysis of signals without introducing errors in the form of spectral components, which inevitably occur during the operation of converters of any type. The use of the generator mode in PMSM diagnostic systems allows obtaining a much cleaner diagnostic signal, which increases the diagnostic accuracy, reduces the number of false diagnoses and minimizes the masking effect. This mode does not require any changes in the structure of the control system, because during the operation of any PMSM, one way or another, when the speed is reduced or stopped, the motors briefly operates in generator mode.

3D МОДЕЛЮВАННЯ ПРОЦЕСУ МАНЕВРУВАННЯ ЧОТИРИВІСНОГО КОЛІСНОГО ШАСІ З ДВОМА ПОВОРОТНИМИ ПЛАТФОРМАМИ

One of the ways to increase the maneuverability of the wheeled vehicles of the National Guard of Ukraine is to use a four-axle wheeled chassis with two turntables, which will allow the machine to turn with the smallest radius, move crab, sideways and turn around its own vertical axis. The creation of such a chassis is associated with a large amount of various experiments and tests of the finished sample. The development of computer technology and technologies has led to the creation of software applications for computer (simulation) modeling, which allow research and study of the properties of technical objects and systems under different conditions. The article developed a digital model of the chassis of a four-axle machine with two turntables and identified its features. For modeling, a powerful package of solid modeling Autodesk Inventor was chosen, which provides a comprehensive flexible set of tools for 3D design, visualization, instrumentation, analysis and calculations. When building a general 3D model of the chassis, the main features of the layout of parts and assemblies of this wheeled vehicle were taken into account. The forced rotation of the wheels and the rotation of the platforms were modeled by entering the value of a single parameter or setting using a graph. Depending on the needs of the experiment, graphs were set for displacements, speed or acceleration. In the course of a visual experiment, a simulation of the maneuvering of a four-axle vehicle was carried out for three options: turning the chassis to move in the opposite direction; changing the direction of movement through the turn of the chassis is a difficult maneuver; turning the chassis for sideways movement. The analysis of virtual studies showed that the control of the front, rear or both turntables is a promising way to increase the maneuverability of wheeled vehicles. In addition, the created computer prototype allows you to determine the main characteristics of the future product, carry out analysis, upgrade and necessary modification, set the desired trajectory of movement, including when passing through obstacles.

Study into torsion compression of hybrid blank made of Al—3Ca—Mn—Zn—Fe—Si alloy

Experimental studies of two blanks made of the same Al—3Ca—Mn—Zn—Fe—Si aluminum alloy are performed. The technology for obtaining a composite (hybrid) blank is associated with a torsion compression scheme and consists in the joint deformation of components from materials assembled into a composite blank, as a result of which they seize under the action of pressure, temperature, and also an increasing deformation in the frictional area of the rotating tool. In this case, the temperature in the joint zone does not reach the values typical for the stir welding process. The results of full-scale experiments and computer simulation modeling performed using the found rheological model of the Al—3Ca—Mn—Zn—Fe—Si alloy are presented. Examples of manufacturing of hybrid blank made of various alloys are given for a comparative comparison of the joint quality.

A system dynamics approach to strategy planning by small and medium-sized enterprises in the renewable energy sector

Small and medium-sized enterprises (SMEs) are key drivers of sustainability. Using a system dynamics computer simulation model, this paper aims to provide a general dynamic model for strategy planning in SMEs working within Iranian renewable energy industry. The model structure covers issues related to sales and marketing, innovation, production, installation, and maintenance. Results from this research showed that as strategies SMEs should build alliances like joint ventures or mutual investment corporations, implement effective mechanisms to capture and use knowledge and experience, and provide their customers, particularly the major and profitable ones with diverse services. The main contributions of this paper are the insights into the SMEs of the renewable energy sector and designing their dynamic work structure to support chief executive officers in strategy planning, and finally, proposing general strategies for the purpose of faster dealing with inquiries and fulfilling the orders regarded as primary attributes of performance.

Combining Soil Water Content Data with Computer Simulation Models for Improved Irrigation Scheduling

Highlights Stand-alone irrigation scheduling models were compared to models combined with soil water content data. Use of soil water content data reduced irrigation recommendations compared to stand-alone models. Cotton fiber yield and water productivity were often not significantly impacted by the reduced irrigation amounts. Weather station aridity and other measurement uncertainties must be addressed to improve the methodology. Abstract. Irrigation scheduling models can be used to guide irrigation management decisions, but their simulations often deviate from reality. Combining in-season field data with models may improve the simulations, leading to better irrigation decisions and improved agronomic outcomes. The objective of this study was to evaluate cotton fiber yield and water productivity outcomes from a field trial that compared three computer simulation models for irrigation scheduling: (1) AquaCrop-OSPy (AQC), (2) the CROPGRO-Cotton module within the DSSAT Cropping System Model (CSM), and (3) the pyfao56 evapotranspiration-based, soil water balance model (FAO). Six irrigation scheduling treatments were established, including the three models used as stand-alone scheduling tools (AQC, CSM, and FAO) and the use of the three models in combination with weekly soil water content (SWC) data from neutron moisture meters (AQCSWC, CSMSWC, and FAOSWC). Two cotton varieties were also evaluated (NexGen 3195 and NexGen 4936). The field trial was conducted during the 2021 and 2022 cotton growing seasons at Maricopa, Arizona. Seasonal irrigation amounts were different among irrigation scheduling treatments (p < 0.05), with 9–21% less water recommended for the AQCSWC, CSMSWC, and FAOSWC treatments as compared to AQC, CSM, and FAO. In 2021, the differences in irrigation amount did not lead to any statistical differences in fiber yield among irrigation treatments, but water productivity for the stand-alone CSM model was significantly reduced compared to the other five irrigation treatments (p < 0.05). In 2022, treatments based on soil water content data reduced yield by 15% as compared to stand-alone model treatments, but the reduction was significant only for FAOSWC. Water productivity differences in 2022 were due to the choice of model rather than the inclusion of soil water content data. In both years, the shorter-season cotton variety (NexGen 3195) yielded greater than the longer-season variety (NexGen 4926), and the former achieved greater water productivity than the latter through the yield improvements (p < 0.05). Taken together, the results suggest that combining soil water content data with irrigation scheduling models was useful for reducing irrigation amounts while often maintaining cotton fiber yield and water productivity; however, issues with weather station aridity and other measurement uncertainties must be addressed to improve the methodology. Keywords: Cotton, Evapotranspiration, Irrigation, Management, Sensor, Simulation, Water.

Thermal Infrared Radiance Transfer Modeling of the Urban Landscape at Ultrahigh Spatial Resolution

The land surface temperature (LST) of urban is a key factor in the field of urban environmental monitoring, and thermal infrared (TIR) remote sensing is an efficient method to obtain it. An important assumption of the traditional thermal radiance transfer model is that the land surface is flat, which has now proven difficult to hold under the urban landscape. Most of the existing urban thermal radiance transfer models have been developed for remote sensing images with a spatial resolution of tens of meters. Currently, airborne TIR sensors have the observation capability to acquire remote sensing images with an ultra-high spatial resolution (1 cm to 1 m), and the model needs to be improved. This paper proposed a new ultra-high spatial resolution urban thermal radiance transfer model (UHURT) after analyzing the transfer processes within the urban canopy at ultra-high spatial resolution. Various radiance components, the emitted radiance, reflected atmospheric downward radiance, and adjacent radiance, were modeled separately. The results of the traditional model and the UHURT model were compared with the results of a ray-tracing computer simulation model, which showed that the new model successfully quantifies the multiple scattering and adjacent effects, and obtained images closer to the computer simulation images. Besides, the LST retrieval of the computer-simulated images was performed using the traditional model and the UHURT model, and the proposed model successfully reduced the errors of the retrieval results and weakened the spatial correlation between the residual distribution and the geometric characteristics of the urban landscape.

Computer Simulation Modeling for Pressure Visualization Measurement in Human Motion Mechanics Experiment

With the gradual dissemination of the idea of national fitness, more and more people are paying attention to exercise, which has made human motion mechanics a focus of current research, and the visualization measurement of human motion pressure has also become a focus of discussion. However, current pressure visualization measurement technologies often have problems such as inaccurate measurement results, low visualization level, and low clarity of pressure presentation, which has led to a bottleneck in research on human motion mechanics. In order to better promote the development of human motion mechanics, this article conducted research on the current popular computer simulation modeling technology, indicating that this technology has unique advantages in pressure visualization measurement of human motion mechanics. The measurement effect of computer simulation modeling technology has been demonstrated through experiments. Compared to traditional measurement methods, this method achieved 800 at a pressure of 300 Newton. Compared to traditional methods under the same pressure, the method presented in this article has higher visual clarity and can visually display the pressure situation. This not only benefits people in better studying the mechanics of human motion, but also helps to better formulate exercise plans and engage in correct and scientific exercise. It plays an important role in clinical medical diagnosis, biomechanics, and sports.

Development of a mathematical model of the oscillatory system of agricultural mobile power equipment with attachments for the creation of their adaptive springing systems

A mathematical model of oscillations of a mobile energy means (MEM) is presented and investigated. The proposed MEM oscillation model makes it possible to determine the positions of the MEM center of mass points in various situations on a support base (agrophone) with a different microprofile. Differential equations have been compiled for computer simulation. The solution of differential equations describing the oscillations of the MEM during its movement in a compound with attachments, as well as a computational experiment-simulation modeling were performed in the software complexes Mathcad and MATLAB Simulink. The initial data used are the mass-dimensional and elastic-damping properties of the structural elements of the MEM, based on the TK-3-180 tractor, obtained by calculation and experiment and a real support base (agrophone) with a known micro- and macro profile. The model makes it possible to study the dynamic processes of the oscillatory system “Support base (agrophone) – running system – machine frame with attachments – cab”. The results of computer simulation modeling are presented – graphs showing fluctuations of sprung and unsprung masses of MEM when moving on different backgrounds.

OBJECT PROGRAMMING IN MATLAB RADIO ENGINEERING APPLICATIONS

System objects integrate well with the MATLAB programming language, both when writing simple functions that work interactively in the command window, and when creating large applications. In contrast to MATLAB functions, system objects automatically manage state information, data indexing, and buffering, which is especially useful for iterative calculations or streaming data processing. Such an organization of calculations makes it possible to efficiently process long data arrays. System objects support fixed-point arithmetic and C-code generation from MATLAB and SIMULINK. With system objects, you can generate code for a computer or for an external device. System objects can be used in SIMULINK models in the form of MATLAB function blocks. The issues of the methodology for using MATLAB program modules (files), which are usually called system objects, are discussed. Each such object is a simulation computer model of a real radio engineering device or radio engineering system. Examples of such system objects are given and the effectiveness of their use in the educational process at a technical university is illustrated.

Имитационное моделирование адаптивного идентификатора скорости асинхронного двигателя агломерационной машины

By means of simulation computer modeling, an effective variant of constructing an identifier for the speed of an asynchronous motor of an electromechanical system of a sintering machine is analyzed. The mathematical and algorithmic basis of the adaptive speed identifier (ASI) of an induction motor with a squirrel-cage rotor (ACIM) is given. Using the developed mathematical description of ASI with a reference model and using the apparatus of Lyapunov functions, an adequate computer simulation model was created. Compared with the existing methods for constructing identifiers in sensorless asynchronous electric drives, the proposed version of the ASI allows taking into account the discrete nature of the supply voltage of the ACIM at the output of the frequency converter with pulse-width modulation (PWM) of the output voltage and changing a larger number of equivalent circuit parameters. The stability of the speed identification process is provided in a wide range, sufficient to stabilize the speed of the trolleys according to the requirements of the technological process of sintering machines. As a result, the accuracy of speed identification in static and dynamic modes of operation of the electric drive increases. Simulation confirmed the operability of the proposed version of the identifier, proposed options for setting the AIS components. Universal, important for practical application results have been obtained, which allow both to build a high-precision system for identifying the ACIM speed in general and to refine the setting of the coefficients of the proposed version of the identifier in particular. An important property of the developed version of the ASI is its operability without loss of accuracy at near-zero and zero speeds of rotation and close to the nominal load torque on the ACIM shaft. In this regard, the practical application of the developed version, in addition to the drive of the sintering machine, is also possible in high- precision positioning systems for electric drives for various purposes.

Programming of marine engineers' simulator training

Continuous improvement of the technical equipment of sea vessels is inevitably accompanied by the development and complication of the training base for marine specialists. Simulator training based on a computer model of operating the units of the liquefied natural gas tanker of the Veliky Novgorod type includes interactive computer programs for learning management, created using the e-Tutor computer module included in the simulator delivery set. In the course of systematizing the experience of using specialized programming tools for educational and research activities of students in organizing and conducting simulator training for electrical engineers on computer simulation models of sea vessels, a system of conventional graphic symbols for the elements of the flowchart of the training exercise program has been formed and their description has been given. Training and control exercises include familiarization with the mnemonic diagrams of the integrated marine vessel automation system and assessment of the state of the ship's electrical power system with their help, starting the propulsion electrical installation, providing energy to the operating propulsion electrical installation under load changes, switching on the backup diesel generator unit for parallel operation with the network in normal and emergency modes, acceleration of the vessel to the given speed in accordance with the tasks of the instructor. The advantages of training programming using the e-Tutor computer module are the ability to use the simulator in self-study mode with automated teaching support.