Vol 27, No 2 (2019)

Informatics, Computer Science and Control
Technique of designing immersive simulator for automation of professional training for operators
Glazyrin A.E., Steshina L.A., Petukhov I.V.
Abstract

The technique of immersive simulator designing is presented. It is based on the smart training automation algorithm for operators professional training in ergatic control systems. The technique consists of two levels: low and high level designing. The low- level designing defines the simplest operator’s activities which can be evaluated by means of psychophysiological tests. The high- level designing defines the performance selection metrics: time costs and operating procedure. At each design level, models of fuzzy inference are formed. They include a unified set of rules based on the operator’s performance parameters and the learning environment feedback as difficulty degree changes of the present scenario. The specific feature of the high-level designing is the growing of the rules set because of the increasing number of the environment parameters influencing the difficulty degree of the present scenario.  For solving this problem, a genetic algorithm is used, which is a heuristic combinatorial search for the optimal rule for fuzzy inference. Based on the proposed design methodology, a simulator was developed for training transport-technological machine operators. Experimental data showed an increase in productivity in terms of loading the assortment by 11.6%, a decrease in the time to complete one technological cycle by 10.2% and a decrease in the number of errors by 80%. Thus, the feasibility of using the design methodology in industry for training operators was shown.

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):6-19
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Simulation of the water flow system of a steam boiler
Danilushkin I.A., Kolpashchikov S.A.
Abstract

The paper discusses the experience of developing a dynamic model of a steam boiler water path for creating a computer simulator. The simulator is used to train and evaluate the operating personnel actions of the boiler house when they performs basic technological operations during the working of the boiler. The challenge is to simulate the technological parameters of the plant in all operational modes: from filling the drum with feed water and starting, to working with a nominal load. The model describes the changes in temperature and pressure in the boiler drum, depending on the flow of feed water, continuous and periodic purging, flow of direct steam and gas flow. The model takes into account the heating of the feed water in the furnace walls and the water economizer, as well as the temperature of the feed water entering to the water economizer. The conservation of the energy balance in the model is realized by carrying out all intermediate calculations with respect to the enthalpy of the heat-carrying agent. This implementation allows to correctly take into account the change in the physical parameters of water during heating and pressure growing, ensures the linear behavior of the model, even taking into account the transit of the heat-carrying agent from one state of aggregation to another. The model takes into account the basic technological operations performed by the operating personnel of the boiler house during the boiler starting process. The model identified according to data of the automated control system of a steam boiler obtained during boiler starting. The paper presents experimental data, block diagrams of the main systems of the model, the computer simulation results. It justifies the assumptions that guided the authors in developing the model and describes the limitations that have arisen during its implementation.

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):20-35
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Time-optimal control of the heating process with combined external influences by the boundary conditions
Ilina N.A., Rapoport E.Y.
Abstract

The formulation and method of solving the problem of optimal speed control of the heating process of an unlimited plate with two external influences on the boundary conditions, as one of which is considered the boundary concentrated control of the magnitude of the external heat flow, and the another is the heat flow, determined by a given ambient temperature. The solution of the problem is carried out under the conditions of a given accuracy of uniform approximation of the final temperature distribution over the plate thickness to the specified one. The method of finite integral transformations is used to find the input-output characteristics of an object with distributed parameters with two external boundary effects. The proposed method of solution of this problem is used the preliminary parametrization of control actions based on the analytical conditions of optimality in the form of the Pontryagin maximum principle and the subsequent reduction to the semi-infinite optimization problem, the solution of which is found using the alternance method. The alternance properties of the final resultant temperature state at the end of the optimal process leads to a basic system of relations, which, in the presence of additional information about the shape of the temperature distribution curve, is reduced to a system of equations that is resolved with respect to all the required unknowns. An example of solving the problem of optimal speed control of the temperature field of an unlimited plate with two boundary influences is presented.

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):36-51
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Efficiency analysis of the second-order identifier application in closed loop time-optimal control systems for distributed parameter objects with incomplete information about the plant characteristics
Levin I.S.
Abstract

This paper devoted to one of the most complicated current problem of the modern control theory which is the problem of searching such an optimal control that operates under conditions of incomplete information about the plant characteristics. The statement of a time-optimal control problem is given. The solution of synthesis of optimal control closed-loop system of the induction heating process of cylindrical billets before forging was found. It was found under representative conditions of interval uncertainty of the initial temperature and heat losses values that were considered as the uncertain parameters of the process. An obtained time-optimal control algorithm with feedback was completed initially with a first-order identifier. It is given as a linear function where the uncertain parameters and the feedback coefficients are depends upon the values of measured temperatures at selected points on the billet. The necessity of a second-order identifier were proposed and analyzed. As one of the results of analysis procedure a non-linear correlation between the feedback coefficients and the convection surface heat transfer coefficient was found. The structure of the time-optimal control system for the obtained control algorithm with feedback and the second order identifier was proposed. After the procedure of modeling the obtained closed-loop control systems with first-order identifier and second-order identifier the results have been compared and it was shown that the control system with the identifier of second order provides a much more accurate temperature distribution at the end of time-optimal process that is closer to a deterministic one with complete information about the process parameters.

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):52-63
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Automation of the manufacture of high-frequency wired communication cables of high regularity with cellular insulation
Mitroshin V.N., Kuleshova D.I., Kolesnikova Y.v.
Abstract

The proposed method of controlling the imposition of cellular insulation in the manufacture of high-frequency wired communication cables of high regularity, ensuring the achievement of the required characteristics of the products. The main tasks are formulated when automating the technological process of imposing cellular insulation with extrusion lines. Systems have been developed to stabilize the pressure in the cable head of the extruder and stabilization of the polymer melt temperature in the dosing zone of the extruder have been developed. The analysis of the work of the systems for stabilization of the operating parameters of the process equipment carried out using computer simulation proved their high efficiency.

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):64-76
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System analysis of reliability of district heat supply in Samara
Salov A.G., Sagitova L.A.
Abstract

The paper analyzes the technical conditions of heat supply systems in Samara city. A model for estimating the status of probability of no-failure during the heating season was proposed. The analysis of the technical conditions of the Samara city’s heating networks from 2006 to 2016 was carried on. Analysis revealed that by the beginning of 2017 the length of the heating networks in service and identified for replacement was indicating as 36,7% from entire length of the heating networks.  A mathematical model as exponentiation not uniform function for the assessment of the probability of the trouble-free operation of the heat supply system was developed. The model constructed attributes the length of the networks identified for replacement and the length of the networks maintained in good working order to the probability of the trouble-free operation. The parameters of the constructed mathematical model were identified. The correlation of calculated values with probability calculated from statistical data was evaluated.  Quality assessment criteria for the constructed model attest to a good convergence of model results with calculations based on statistical data.

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):77-87
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Instrumentation, Metrology and Informative-measurings devices and systems
Automatic determination of viscosity by rotary viscosimeter vrts
Korganova O.G., Kuznetsov V.A.
Abstract

If it is necessary to determine the viscosity at a given temperature, various viscometers of various types, mostly rotational ones can be used. These viscometers need to stabilize the frequency of rotation of the measuring rotor and the use of thermostats, since the viscosity is strongly dependent on temperature. A method for measuring viscosity without these disadvantages is proposed. A viscometer contains two channels: a viscosity measuring channel and a temperature measuring channel. Rotation of the measuring rotor is carried out by a drive through a calibrated spring, the angle of its twisting is proportional to the torque, which is converted into a pulse-width signal. The microcontroller measures and analyzes PWM signal and a stress proportional to temperature, converts them into a digital code and outputs the information on viscosity and temperature through the output port in a digital form. The algorithm proposed for processing measurement information eliminates the need to stabilize the frequency of rotation of the measuring rotor.

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):88-98
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Approximation method for determining the pulse signal form and its intensity measurement with an available random noise
Lange P.K., Yaroslavkina E.E.
Abstract

The paper deals with the issues of the operational measurement of a single pulse intensity, as well as the determination of its approximation model. The radar impulse envelope, as well as the peak signal of the analytical instrument, was chosen as the pulse. The pulse square and dispersion were chosen as a measure of intensity. To solve the problem, we use a spline-approximation of discrete samples of the pulse signal. The error of the spline - approximation of the pulse signal discrete values, as well as the error of approximation in the presence of random interference is determined. It is shown that the use of spline approximation reduces the effect of random noise. The characteristics of the proposed method are determined using parabolic¸ as well as cubic spline approximation. The analysis of the error of the considered method caused by the presence of a random additive interference is given. The characteristics of the considered method are determined when analyzing the Gaussian signal. The dependence of the error of the considered method on the intensity of the random noise is determined. The study was conducted for a uniform distribution of random noise. The structure of the system that implements the described method of spline-approximation of the signal samples is described. It is proposed to use the considered approximation method of measuring the pulsed Gaussian signal intensity when solving problems of its detecting against a noise background, as well as determining its boundaries. It is proposed to use the described methods, if necessary, to promptly determine the effective value of a periodic non-harmonic signal (during no more than half of its period) by determining the dispersion of its one half-wave. It is also proposed to use the described methods to determine the informative parameters of a pulse signal (the position of its beginning, end, amplitude).

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):99-112
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Computation of continuous wavelet transform of signals in the basis of the Chebyshev-Hermite functions
Sayfullin R.T., Bochkarev A.V.
Abstract

The paper deals with the development of basis for computation wavelet-transform from the coefficients given by decomposition original signal with Chebyshev-Hermite functions. Decomposition with Chebyshev-Hermite functions allow to transform original signal into coefficients, that can be used for reconstructing different transforms of original signal like Fourier transform, derivatives of different orders, wavelet transform and others. These transforms can be obtained by using corresponding bases. In this paper considered basis for wavelet-transform with derivative of Gauss functions as wavelet. This basis is computed by applying continuous wavelet transform with derivative of Gauss functions as wavelet into the Chebyshev-Hermite functions. For estimating error of Chebyshev-Hermite wavelet basis reduced error are used. Arrays of the wavelet coefficients are presented as 3D plots. The Mathematica 11.3 computer algebra system was used to calculations and graph the results.

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):113-124
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Mathematical model of multi-channel analog-digital converter with optimum code selection procedure
Khrisanov N.N.
Abstract

Multichannel converters are usually built based on the traditional multiplexer-analog digital converter (ADC) scheme, and the increase in speed is ensured by the improvement of the element base, the use of improved circuit design solutions. Based on the application of the principle of logical deployment, a structure of a multichannel analog-to-digital converter is proposed, a distinctive feature of which is the use of an optimal code selection procedure that takes into account the dynamic parameters of the digital-to-analog converter (DAC) and the probabilistic characteristics of the input signals. The process of functioning of a multi-channel ADC is represented as the execution of a certain set of strategies for searching for a set of codes corresponding to the input signals. Each strategy consists of a sequence of tests, characterized by execution time, and the probability of its positive or negative outcome. The execution time of each test depends on the number of the previous one. The probability of a particular outcome of the test depends on the distribution function of the input signals. The derivation of the formula for calculating the average execution time of search strategies is given. he method of solving the construction of optimal strategies based on the branch and bound method, with the calculation of  lower bounds by solving the problem of the least coverage, is indicated. The estimation of the increase in the ADC speed is given taking into account the probability characteristics of the input signal, taking into account the dynamic parameters of the DAC. It is shown that the application of the proposed transformation scheme allows to increase the conversion speed several times.

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):125-135
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Electrical Engineering
Numerical mathematical model demagnetization of rails in rail welding production
Khristinich A.R., Khristinich R.M., Khristinich E.V.
Abstract

A three-dimensional numerical mathematical model is considered for studying the effectiveness of rail lash demagnetization in rail welding production. The main assumptions for solving the electromagnetic problem of the «inductor-rail» system are presented, the boundary conditions are determined, the current loads of the sources of the electromagnetic field are specified, and the boundary conditions of the problem are determined. The calculation of the electromagnetic field of the model «inductor-rail» is performed in the ANSYS software package. The numerical mathematical model allows to investigate the process of rail demagnetization when exposed to a lower frequency electromagnetic field. The effective parameters and characteristics of the rail demagnetization unit are determined to achieve the greatest effect of rail demagnetization.

Vestnik of Samara State Technical University. Technical Sciences Series. 2019;27(2):136-147
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