ISSN 0021-3454 (print version)
ISSN 2500-0381 (online version)
Summaries of the issue


In the process of experimental testing of an aircraft being created, it is impossible to obtain homogeneous data on its control system characteristics, due to differences in test conditions for individual samples. To improve the quality of the characteristics assessment, the test results are recalculated to some preset conditions. Two methods are proposed for determining recalculation operators, which make it possible to improve the accuracy of estimating the control system characteristics. A demo example is provided.
The influence of the choice of a discrete quadratic quality index in calculation of a digital servo system on the character of its transient response is considered. It is shown that when choosing a quality indicator in the form of the sum of squares of the first difference of the discrete transient response, the overshoot turns out to be the smallest. A necessary and sufficient condition for eliminating hidden oscillations is proved, which requires that “all zeros” of the numerator of the discrete transfer function of the continuous part be included in the numerator of the desired transfer function. It is established that in order to improve the quality of the transient process, it is necessary to reduce the sampling period while maintaining the time of the transient process.
The computational processes of obtaining input data, data processing, preprocessing in the database, storing in the database, and also outputting data to the user are considered. Graphic-analytical and software models of the computational process are developed. With the help of these models, it is possible to verify the computational process in the information system. As an example, the computational processes in the 1C:Enterprise information system are considered.
A method for digital processing of the image of sighting target contour in the frequency domain is presented, which makes it possible to significantly improve the accuracy of the optoelectronic device when measuring the angular coordinates of objects. The contour of the sighting target image is represented in the complex plane by constructing its profilogram relative to the base circle. To analyze and calculate the errors in determining the contour, the Fourier image of the expanded profilogram of the target contour is obtained by applying a discrete Fourier transform, which makes it possible to determine the scattering characteristics of the random component of the error in measuring the coordinates of the center of the sighting target contour and to evaluate the errors of its image parameters measurement. The contour parameters of the sighting target are determined using the Spragg formulas by solving the optimization problem of calculating the minimum of a smooth objective function. According to results of target image filtering with the help of an ideal high-pass filter, the absolute error in measuring the sighting target angular coordinates is reduced by more than two times relative to results obtained using the least squares method. The application of methods of digital image processing of the sighting target in the frequency domain enables to bring the measurement error of the angular coordinates of the optoelectronic device within the limits of the permissible average square error of angle measurement for a total station of technical accuracy class.


TESTING OF IR SENSORS USING A REFERENCE THERMAL SIGNAL GENERATOR Evgeny V. Larkin, Dmitry V. Titov, Tatiana A. Akimenko, Tamara A. Shirabakina
Methods for testing IR sensors, which are widely used as a source of information about the environment in various sectors of the national economy, are being investigated. It is shown that due to the transformation of the informative parameters of the observed scene by the sensor, information loss at the output of the device is possible. Conditions are derived under which there is no loss of information, and three general cases of transmission of informative parameters with losses are specified. The structure of the testing system is developed, the main element of which is a patented generator of reference test signals, which makes it possible to evaluate such informative parameters as a thermal signal characteristic, distortion, and resolution. The heat signal characteristic is built as a result of heated plates scanning, statistical processing of measurement data, and approximation of the results of statistical processing by a linear dependence. Distortion is inferred from results of measuring the IR LEDs coordinates in the scene created with the reference test signals generator. The resolution is estimated based on the results of constructing the surface of values of the output signal of the IR sensor when scanning the heat-generating plates. For each case, an appropriate assessment methodology is proposed.
The purpose of the work is to modify the known transformer oil moisture meter by mounting a thermostat on the desorption column with the possibility of raising the temperature and to study the degree of completeness of water extraction from the oil matrix. The principle of operation of the moisture meter is based on the electrochemical method, which includes several successive stages: extraction of water molecules from the oil matrix by dry gas in a desorption column at elevated temperature, transfer of the vapor-gas phase by dry gas to a sensitive element, and subsequent electrolysis of water. A measure of the water content in oil is the current strength required for the electrical decomposition of water absorbed per unit time. The modified moisture meter (desorption column with thermostat), in contrast to the standard version of the device (desorption column without thermostat), allows one to measure the mass fraction of water in old oxidized oils from existing high-voltage transformers with higher accuracy. Results of performed research show that heating a liquid dielectric sample to 80 °C leads to a decrease in the viscosity of transformer oil. This fact contributes to the most complete extraction of water from the matrix of the insulating liquid. Reliable measurement of the mass fraction of water in a liquid dielectric is one of the important tasks in diagnosing the state of the insulation system of expensive high-voltage transformers.
The issues of studying the optical properties of aviation technical washing liquids in the ultraviolet wavelength range are considered. Correct identification of cleaning fluids for washing the gas-air path of a gas turbine engine is essential for ensuring flight safety. The method of ultraviolet spectroscopy is presented and the optical scheme of the spectrofluorimetric analyzer is given. The spectral dependences of the absorption coefficient of the studied media mixed with distilled water are measured, and the maximum values of the absorbance of the studied samples in the ultraviolet wavelength range are determined.


A method of designing forming parts of injection molds is presented. Results of analysis of the gating system parameters are presented in the form of a table of dependences on parameters of a polymer product. The obtained results can be used in the development of a knowledge base.


The necessity of increasing the efficiency of automatic classification of visual stimuli by single evoked potentials on the observer's electroencephalogram is substantiated. The factors affecting the accuracy of recognition of the type of presented visual stimuli (living/non-living, clear/blurred) are determined. A data processing algorithm is developed that makes it possible to identify significant differences in the amplitudes of single evoked potentials.
A technology of centering IR lenses with one aspherical surface is considered. The centering procedure is combined with shaping the aspherical surface on a diamond micro-turning machine. Recommendations are given on setting tolerances for lens thickness and air gaps in IR lenses when using this technology.