6 use [3]. Ultimately, wear can be considered as an integral process leading to the final result: a decrease in initial shell velocity and an increase in its spread from shot to shot as a random variable [4]. In addition to the military-applied aspect, the artillery barrel wear has a material economic aspect. The cost of barrels of current large-caliber artillery systems is estimated at 30-35 % of the cost of the system in general. Further operation of the barrel which has reached the maximum level of wear can lead to its complete, irrecoverable failure. In this case, the measures of replacement and disposal of out-of-service barrels lead to large economic and time losses. The methods used today for assessing wear of artillery barrels are either obsolete and rather approximate or based on modern technologies requiring expensive job-dedicated equipment. The latter methods are very costly and time-consuming. At the same time, it is known that an artillery shot creates powerful acoustic fields that can be recorded at sufficiently large distances. According to [5], analysis of the acoustic fields accompanying firing can be used to find out 6 APPLIED PHYSICS

6 (accompanying the shell flight) and muzzle (created by powder gases flowing out of the gun barrel under high pressure). To determine coordinates of the firing gun, acoustic waves can be recorded by a system of spaced microphone sensors. In 1. Introduction Powerful acoustic fields are formed with each artillery shot. These fields are mainly formed by two waves: ballistic

No abstract

An artillery shot is accompanied by the release of combustion products of powder gases from the barrel. It is proposed to usemuzzle ejection to classify the level of barrel wear during firing. A full-scale experiment was carried out with high-speed video recording in the visible and infrared ranges of the dynamics of the development of muzzle ejection when firing guns with a defect-free and worn barrel. Muzzle ejection when fired from a large-caliber gun consists of three spatial regions: frontal and two side, associated with the emission of powder gases through the openings of the compensators. A technique for analyzing three synchronized video streams has been developed. The technique made it possible to quite fully investigate the processes of muzzle ejectiondevelopment dynamics in defect-free and worn barrels. Informative signs are chosen, which are different for the dynamics of muzzle ejection from defect-free and worn barrels. This madeit possible to build a binary classifier of the condition of the trunks by the level of wear based on the support vector machine with least squares. In contrast to the classical SVM classifier, thisallowed us to reduce the calculation time and reduce the required size of the training set. To assess the quality of classification, it is proposed to rely on only errors of the first and second kind, but also an integral indicator –the probability of error-free classification. To increase the reliability of the classification, the concept of a universal binary classifier is proposed, which uses both video recording of the muzzle ejection and acoustic fields of the shot –ballistic and muzzle waves –to diagnose the state of the barrel. On the basis of experimental data, it is shown that the use of all physical fields accompanying an artillery shot for the binary SVM classification allows obtaining a high value of the error-free classification probability.

The widespread use of current transformers both in relay protection systems and for measuring purposes makes the task of estimating their errors quite urgent. The permissible error levels of modern measuring current transformers should not exceed a fraction of a percent. Moreover, the errors of multi-range current transformers with incomplete filling of the magnetic circuit with secondary windings are determined distribution of the magnetic field in the magnetic system, depending on the scattering fluxes of the windings. The analysis of the capabilities of various software products that implement the finite element method for the calculation of electromagnetic systems. It has been established that, to the greatest extent, for the study of the magnetic field of current transformers by users without special training, is the FEMM software package. Using this program, we studied the distribution of the magnetic field of the current transformer when the magnetic system is not completely filled with turns of the secondary winding and with a different arrangement of the return wire of the multi-turn primary winding relative to the secondary winding for a current transformer with a toroidal magnetic system. For a transformer with a rectangular magnetic system, a magnetic field is simulated for one and two secondary coils. The characteristics of the distribution of the magnetic field in the magnetic system and the normal component of the scattering field of the transformer have been obtained. The diagrams of the magnetic field vectors are constructed for different sections of the transformer magnetic system. It is shown that when the magnetic system is incompletely filled with turns of the secondary winding, a significant uneven distribution of magnetic induction along the magnetic circuit occurs, which leads to an increase in the error of the current transformer. Studies have shown the effectiveness of the finite element method for modeling magnetic fields and error estimation of current transformers. The FEMM software environment used for research is a universal and accurate information technology for calculating current transformers, convenient for users without special training.