JSC «SSC RIAR» is developing a design of an irradiation device (ED) for in-reactor tests of absorbing materials of nuclear reactor control bodies. Dysprosium titanate was chosen as the absorbing material because this compound has high chemical and thermal stability, increased corrosion and radiation resistance. The structure of the DT consists of a suspension with a flange, a working section, in which the sample with the absorbing material is placed, a flow splitter and an absorbing screen. The flow divider is made of 12X18H10T steel. The absorbing screen, designed to reduce the fraction of thermal neutrons in the spectrum, consists of two cylinders made of boron steel and aluminum, goggled by 12X18H10T steel. In the course of the work, neutron-physical calculations obtained with the MCU-FR code and thermal hydraulic calculations of the SE structure obtained with the SolidWorks PC were performed. Neutron-physical calculations showed that the use of boron steel and aluminum shields allows correcting the ratio of fast and thermal neutron flux during in-reactor tests of absorbing materials.

The results of thermal-hydraulic calculations have shown that the required temperature regime of irradiation of the sample with absorbing material made of dysprosium titanate in the third row of the SM-3 reactor reflector is provided under the conditions of forced circulation.

Pulse propagation in optical fiber described by the generalized Kaup–Newell equation with arbitrary refractive index is investigated. Using traveling wave variables the generalized Kaup–Newell equation is reduced to a system of nonlinear differential equations. Compatibility conditions for the system of equations are found. Exact solutions of the equation with fixed n = 1 expressed by an elliptic Weierstrass function and an elliptic sine are obtained. Using the generalized simplest equation method, exact solutions of the equation in the form of solitary waves are found for an arbitrary refractive index. Mathematical model with periodical boundary conditions is formulated. Using pseudo-spectral method the numerical solution on a regular grid is constructed. The program code of the numerical solution for the problem is verified by comparing the numerical solution with the analytical one in the form of solitary waves. The error dependence on a step of grid is studied taking into account the restrictions on the model parameters. Figures of analytical and numerical solutions were constructed and analyzed.

Transformations for non-linear partial differential equations with a variable coefficient are presented. It is shown that the integrability properties for some equations with variable coefficients are satisfied in a natural way, since these equations are transformed to well-known integrable partial differential equations.

The article describes the air monitoring system of office premises designed to assess air quality. The urgency of the task of creating air quality monitoring systems is due to the fact that the air environment contaminated with harmful chemicals can have a negative impact on humans.

The developed system includes information-measuring and information-analytical blocks that meet certain requirements, such as sensitivity, selectivity, speed and compactness. The main task of the information and measurement module is the detection and identification of harmful chemicals. The purpose of the information and measurement module is to determine concentration, velocity and temperature fields at any time at any point in the room.

The approbation of the developed system was carried out on the basis of experimental studies. Butyl acetate was selected as a contaminant. The source of the contamination was located near the ventilation system. Modeling of the spread of pollutants in the room is performed in the Solidworks 2020 software package. The distribution of butyl acetate concentration in an office space at the level of the human respiration layer is obtained, taking into account the location of the source of pollution and the workplace, as well as taking into account the time of year. The values of butyl acetate concentration at various points of time at the employee's workplace were determined.

The simulation results showed that in the summer, due to a slight difference in outdoor and indoor air temperatures, the concentration of butyl acetate at the employee's workplace reaches the maximum permissible values much faster than in winter.

In this paper, we propose an approach for the pinpoint detection of inoperable sensors based on the analysis of diagnostic parameters. Such parameters can be the "sliding correlation" coefficients, the fourth eigenvalue and the relative deviation of the reconstructed sensor reading. With the help of the above diagnostic parameters, it is possible to immediately determine the fuel assembly in which one of the DPZ is presumably out of order, then analyze the level correlations between each other and, using the restored value, make a final judgment on the performance of each altitude sensor.

The developed software makes it possible to carry out an express analysis of the archive of the VVER reactor. This has scientific and practical value in the context of improving the quality of work of operational personnel and analyzing situations that require additional attention and more detailed analysis. The application of this approach can help detect malfunctions in sensors and take timely measures to prevent possible problems and emergencies, which is an important step in ensuring the safety and efficiency of the VVER reactor monitoring and control system.

Strontium hexaferrite with the formula SrFe₁₂O₁₉ was obtained due to citrate method. A feature of the synthesis is a relatively low production temperature – 700 °С. The X-ray diffraction study revealed the single-phase state of the obtained material due to the complete correspondence of the positions of the diffraction maxima on the experimental XRD pattern with the positions on the reference XRD pattern of strontium hexaferrite from the ICDD data base. An image of the sample obtained with a SEM method at a magnification of 50000 indicates the nanodispersed state of strontium hexaferrite particles. The method of DSC revealed the Curie point located at 450.9 °С. An analysis of the hysteresis loops obtained at 300 and 50 K indicates the obtained magnetically hard material in a single-domain state and the growth of magnetic parameters in conditions of low temperatures, which slows down upon cooling to 100 K. The studies were carried out using a Rigaku Ultima IV diffractometer with CuK_α radiation and a scanning speed of 2°/min, a JEOL JSM-7001F electron microscope with an EDS Oxford INCA X-max 80 energy-dispersive spectrometer, a Netzsch STA449C F1 «Jupiter» thermal analyzer upon heating to 600 °C with a speed of 10 °С/min in air atmosphere, Quantum Design PPMS VersaLab vibrating magnetometer at a temperature of 300 and 50 K with an applied magnetic field of up to 3 T.

An experimental study of the use of lithium niobate substrates for radio frequency identification 64-bit tags on surface acoustic waves (SAW) in the frequency band of 33 MHz at the center frequency of 870 MHz was carried out. Marks make it easy to distinguish between orthogonal codes, since they have sufficient dynamic range and an acceptable noise level. Aspects of manufacturing technology and the effect of spraying reflectors in marks on the main parameters of products are considered. It is shown that the use of strips in reflectors instead of IDTs improves the uniformity of impulse responses, but leads to an increase in insertion loss. RFID tags were studied, in which the deposition thickness of the aluminum film, from which the IDT and reflectors were made, had different thicknesses. Studies have shown that the deposition thickness has a significant effect on the electrical parameters of the label. The deposition thickness depends on the number of reflectors in the marks and is selected in such a way as to ensure minimum insertion loss and maximum dynamic range. The technology is selected in such a way that, with a high probability, responses are obtained with an unevenness of no more than 3 dB, insertion loss in the range of 38–40 dB.

Methods of generalized and functional separation of variables used to find exact solutions to nonlinear equations of mathematical physics are considered. A direct method for constructing reductions (in many ways similar to methods of functional separation of variables) and its more general version based on the principle of splitting are described. The equations of heat and mass transfer, wave theory, hydrodynamics, nonlinear optics, combustion theory, chemical technology, biology and other physics, heat and mass transfer equations, hydrodynamic equations are studied.