### INFORMATION TECHNOLOGIES AND SYSTEMS, COMPUTER TECHNIQUE

METHOD FOR ESTIMATING THE PERFORMANCE
OF LARGE INFORMATION SYSTEMS WITH TRANSACTION CLUSTERING
Shelest Maria N. , Tatarnikova Tatiana M.

623

A method for estimating the upper and lower bounds of large information system performance with the account for the system data integrity requirement, is proposed. The integrity is ensured by locking the computing resources necessary for the transaction execution and releasing them when the transaction is completed or cancelled. Clustering of transactions allows for parallel processing of different user requests belonging to different clusters. The features of query processing give no way of analytical assessment of large information systems performance, and a full-scale or simulation experiment is time consuming. The model of a large information system is formalized in the form of a mass service network. The complete set of routes in the queuing network is given by the number of clusters of similar transactions. The performance is estimated by the system response time.

APPLICATION OF METHODS
OF FRACTAL IMAGES ANALYSIS IN SOLVING ENVIRONMENTAL ASSESSMENT
AND OBJECT RECOGNITION PROBLEMS
Oleg V. Esikov, Dmitry V. Titov

630

An approach to improving the efficiency of the image pattern recognition system in monitoring and sensing complexes, and in unmanned vehicles based on the use of an additional classification feature is proposed. Tasks to be solved in sensing complexes when constructing an object recognition system are listed. To form an additional characteristic of the object, the value of the fractal dimension (fractal signature) of its contour image is used. Results of fractal analysis of traffic objects images are presented. Fractal analysis of images of territories affected by natural disasters is demonstrated. To construct a dimension map and a fractal dimension histogram, the application of the Minkowski dimension is proposed. The results of experimental verification of the proposed methods and algorithms operability are presented.

MODEL FOR ASSESSING
THE READINESS OF COMPLEX TECHNICAL SYSTEMS
TAKING INTO ACCOUNT
THE METROLOGICAL CHARACTERISTICS OF CONTROL TOOLS
Ekaterina А. Kopeyka, Alexander L. Kopeyka, Anatoly M. Baranovsky

640

The issues of ensuring the reliable functioning of complex technical systems during operation by carrying out scheduled maintenance with the use of controls are considered. The possibility of conducting simulation modeling in order to evaluate the most important indicators of system reliability, for example, the availability coefficient, taking into account the metrological characteristics of the control means, is being investigated. The study is declared to be of great importance for confirming theoretical statements about the influence of quality control on reliability indicators. Analytical and simulation models for assessing the readiness indicators of a complex technical system are proposed. Simulation modeling is carried out on the basis of the AnyLogic software environment, the obtained results are used to construct dependences of the system readiness coefficient on the metrological characteristics (control errors) of applied control tools and service parameters.

ALGORITHM FOR PREDICTING THE STATE OF EQUIPMENT
BASED ON MACHINE LEARNING
Maxim R. Salikhov, Radda A. Yureva

648

Analysis of production equipment sensors readings is carried out and a data aggregation technique is presented to assess the probability of equipment failure. The study relevance is due to the insufficient development of the scientific and methodological apparatus for assessing equipment condition based on big data. In order to form a data set intended for development of a predictive model of the equipment state, a number of features characterizing the state of machine with numerical program control are constructed. Practical significance of the study is related with the possibility of including the generated data set in the production process and using it to save the values of equipment parameters in time and within the established limits, which characterize its ability to perform the required functions in the specified modes and under the necessary conditions of use.

### DEVICES AND SYSTEMS OF AUTOMATIC CONTROL

COORDINATED WORK OF TWO MOBILE ROBOTS
WHEN PERFORMING OPERATIONS AUTOMATICALLY
IN A COMPLEX ENVIRONMENT
Vladimir V. Filaretov, Alexey A. Katsurin

656

The problem of controlling a manipulator mounted on the main mobile robot performing operations in cramped working environment conditions when objects of work are out of sight of the robot's technical vision system, is considered. In this situation, location of the invisible objects is first determined using the technical vision system of an auxiliary and more maneuverable mobile robot in its associated coordinate system, and then this information is transmitted via communication channels with unavoidable errors to the associated coordinate system of the main manipulation robot. An algorithm is proposed to determine and eliminate the aroused errors, which as a result provides the possibility of accurate automatic execution of the required operations with the objects of work. The proposed mathematical apparatus allows for accounting variations in current spatial orientation of the base platforms of both mobile robots at the angles of roll, pitch and yaw in the absolute coordinate system. The results of experiments confirming the operability and high efficiency of the proposed method of coordinated automatic operation of two mobile robots in cramped environmental conditions are presented.

### HEAT REGIMES AND RELIABILITY OF INSTRUMENTS AND SYSTEMS

PROMISING METHODS FOR MEASURING THE THERMAL CONDUCTIVITY OF SOLIDS
Vyacheslav P. Hodunkov, Yury P. Zarichnyack

668

Two new methods of measuring the thermal conductivity of solids are considered, based on the use of absolute and relative measurements of the initial thermal quantities that determine the value of the measured parameter. In the presented methods, the influence of traditional negative factors of experimental technique on the accuracy of the results obtained is maximally reduced.

### SCIENTIFIC AND PRACTICAL DEVELOPMENTS

MODEL OF SPATIAL-TEMPORAL SYNTHESIS
OF THE COMBINED APERTURE FUNCTION
OF SPACED ANTENNA ARRAYS
Andrey P. Aleoshkin , Pavel V. Savochkin, Aleksandеr V. Chestnykh, Stanislav N. Balakirev

677

A technique for narrowing the antenna pattern based on joint spatial-temporal processing of signals received at successive moments of time by spatially separated receiving antenna arrays of a quasi-monostatic decameter early warning radar system is presented. The technique application makes it possible to increase the probability of detecting objects located outside the line of sight against the background of powerful interfering interference caused by both the propagation medium and reflections from the underlying surface. The implementation of the methodology will improve the reliability of determining objects located by decameter radar systems.

CALCULATION OF OBSERVATION PERSISTENCE DURING RADAR SURVEY
Vladimir V. Zaytsev

685

A mathematical approach is proposed to calculate the duration of survey by a spacecraft equipped with a synthetic aperture radar to assess the potential capabilities of the observation system. The geometry of the radar survey is characterized by a system of three equations governing the slant range, the rotation ellipsoid, and the Doppler frequency of the received signal, which are specified in a three-dimensional inertial coordinate system associated with the Earth. This system of equations does not have an explicit solution, therefore, a variant of solving the problem of identifying the analytical relationship between the parameters characterizing the position of the spacecraft on the trajectory and the angles of its rotation, the angles of deflection of the antenna pattern, and the parameters of probing pulses is proposed. To simplify the solution, the local sphericity of the Earth is assumed in the survey area with a known local radius. Determination of the survey duration is required to select the necessary radar operation mode in order to obtain a radar image of the observation area with the wanted resolution within a given capture band. A technique for planning an area survey with a radar based on calculation of the observation duration is presented. Relationships are obtained that make it possible to evaluate the capabilities of a radar in solving survey problems or in designing a surveillance system, as well as to determine reasonable requirements for choosing the main characteristics of a radar and ballistic parameters of a spacecraft constellation.