The paper presents the synthesis of a tracking system for a quadrocopter considered as a solid body with six degrees of freedom and four control actions (rotor lift forces), considering design constraints on velocities and controls. The plant operates under conditions of parametric and external disturbances, as well as incomplete measurements. The trac king loop is designed in a typical way and consists of translational and rotational motion subsystems with three inputs and three outputs each. Reference trajectories are independently specified for the spatial position of the quadrocopter’s center of mass and yaw angle. The pitch and roll angles have a dual function: in the translational motion subsystem they, together with the total lift force, act as controls, which are considered as reference actions in the rotational motion subsystem. Scientific novelty is related to the developed method of dynamic feedback design using piecewise linear feedback with saturation in regulators, state and disturbance observers, as well as dynamic differentiators of reference actions. Application of the block control principle with combined piecewise linear feedbacks with saturation for design of tracking subsystems of spatial and angular positions allowed to provide stabilization of tracking errors at imposed constraints on velocities and controls. Reduced dynamic observers with piecewise linear correction reduce the computational load. Based on tracking error measurements, they recover composite signals including unmeasured velocities, uncertain parameters, and external disturbances to a specified accuracy without the need for individual identification of uncertain parameters. The feedback formation on the variables of such observers ensures robustness of the tracking system. Instead of numerical differentiation operations, which are problematic to implement, dynamic differentiators with piecewise linear correction are used to recover derivatives of reference actions, which are capable of processing piecewise differentiable signals and do not generate surges of estimation signals at special points. The presented results of numerical modeling confirm the effectiveness of the developed algorithms

We have studied the thermal expansion of CaIr4B4, IrB1.1, and CaB6. The results demonstrate that the crystal lattices of these phases expand linearly with temperature and that their thermal expansion coefficients lie in the range (5–10) × 10–6 K–1. We have determined the average microhardness of the CaIr4B4, IrB1.1, and CaB6 phases. The average microhardness of the CaIr4B4 phase is 15 GPa, which is a factor of 3 lower than that of the CaB6 phase.

Experimental studies of the shock wave properties of two epoxy resins with the same composition but different curing temperatures (160 and 200 °C) at up to 330 GPa pressure have been carried out. Laser interferometry was used to record particle velocity profiles at up to 73 GPa pressure while measuring the shock wave velocity. The release sound velocity was experimentally determined in the 3–73 GPa pressure range. Cumulative explosive shock wave generators were used to study the shock Hugoniot of epoxy resins at pressures above 100 GPa. It was shown that the shock compressibility data of both samples are approximated by a single shock Hugoniot within the experimental error. A kink on Hugoniot recorded close to 25 GPa pressure indicates a chemical decomposition in epoxy resin. Above this kink, a change in the shock wave front structure was recorded. Hugoniots of epoxy resin and unidirectional carbon/epoxy composite were compared at up to 370 GPa pressure.

Впервые исследована новая керамика «Идеал», композит алмаз — карбид кремния, полученная в реакционно-диффузионном процессе Тьюринга, что позволяет получать материалы с оптимальным набором физико-механических свойств. Отмечается упруго-хрупкое разрушение, связанное с распространением ударной волны в двухкомпонентной системе. Найден динамический предел упругости, определяемый свойствами карбида кремния, равный 13.4 ГПа. Проведены измерения ее динамического предела упругости и откольной прочности в области упругого деформирования. Определена ударная сжимаемость керамики до давления 625 ГПа.

This paper presents a nonlinear discontinuous control law that allows stabilizing the output voltage of a step-down voltage converter in conditions when the input voltage and load current are unknown. The main idea is based on the use of the so-called vortex algorithms, which ensure invariance with respect to external unmatched disturbances. The efficiency of the developed algorithms is shown by numerical simulation.

Проведены эксперименты по исследованию неустойчивости детонационных волн в смесях нитрометана, тетранитрометана и ФИФО с инертными разбавителями посредством регистрации свечения детонационного фронта скоростной восьмиканальной шестнадцатикадровой электронно-оптической камерой НАНОГЕЙТ-22/16. В области неустойчивости детонации зарегистрировано неоднородное свечение детонационного фронта, которое связывается с турбулентным течением в зоне реакции. Формирование ячеистых структур с реакцией взрывчатого вещества в косых и поперечных волнах в исследованных составах не наблюдалось. Experiments are conducted to study the instability of detonation waves in mixtures of nitromethane, tetranitromethane, and FIFO with inert diluents by recording the detonation front glow with a NANOGATE-22/16 high-speed eight-channel sixteen-frame electron-optical camera. In the detonation instability region, the detonation front exhibits a nonuniform glow, which is associated with a turbulent flow in the reaction region. The formation of cellular structures with the reaction of the explosive in oblique and transverse waves is not observed in the compositions studied.

The detonation properties of mixtures of gelled nitromethane (NM) with hollow glass microballoons (GMBs), the concentration of which varied from 16 to 30 wt. %, have been studied using an optical technique with high temporal and spatial resolution. It is shown that the addition of GMBs up to 30 wt. % does not qualitatively change the reaction zone structure of NM, which is in accordance with the classical detonation theory. However, the detonation parameters of the mixture decrease significantly with increasing GMB concentration—the pressure at the Chapman–Jouguet point drops by more than an order of magnitude at a porosity of 75%. The non-monotonic nature of the change in critical detonation diameter with decreasing mixture density is noted. The dependence of the critical diameter on the porosity of U-shape with the formation of two local minima at 8 and 18 wt. % GMB in the mixture and a local maximum at 13 wt. % GMB is obtained. At a concentration above 20 wt. % GMB, the critical detonation diameter increases dramatically, and at 30 wt. % GMB, the critical diameter becomes comparable to that of gelled NM.

The ternary TaIr2B2 boride was prepared by the reaction between iridium and TaB2 powders. It was shown that a choice in favor of any crystal structure of TaIr2B2 boride using only X-ray powder diffraction analysis and single-crystal XRD is rather difficult to make. The DFT calculations were carried out to predict the energetically preferred crystal structure of TaIr2B2. The 11B solid-state NMR spectrum of TaIr2B2 was recorded for the first time. A combination of diffraction and spectroscopic methods, as well as theoretical calculations, allowed us to make clear choice in favor of the triclinic space group P-1 for the crystal structure of TaIr2B2. The Vickers microhardness value for TaIr2B2 was found to be 17.9 ± 2.3 GPa, and the ternary TaIr2B2 boride can be considered a hard material. Therefore, the family of hard ternary boride phases got a new member. The coefficients of thermal expansion of TaIr2B2 measured by in situ high-temperature XRD analysis are independent of temperature along the a and b axes, but the CTE along the c axis deviates noticeably at elevated temperatures. The findings for the new ternary TaIr2B2 boride are of interest for the rational design of complex structural materials containing Ta–Ir–B-based components and prediction of their high-temperature behavior. Further research into this ternary boride as well as other iridium-containing ternary borides will provide a tool to solve the problems faced by high-temperature materials science.

In this work, numerical experiments were carried out in the framework of the molecular dynamics method to study the impact interaction of metallic nanoclusters of different sizes with a metallic substrate in a wide range of velocities. Analysis of the data obtained showed that the crater volume remains proportional to the impact energy and inversely proportional to the dynamic strength of the material, with the line slope being independent of the cluster size and the cluster–substrate material.

Experiments are performed for studying the process of shock wave initiation of detonation in pure tetranitromethane and its mixtures with acetone, nitrobenzene, and methanol. The glowing of the detonation front is detected using streak cameras and frame-by-frame photography. It is found that detonation both in pure tetranitromethane and in its mixtures with dilutants is initiated at localized sites. The number of these sites, the character of their formation, and the features of their growth and merging depend on the nature of dilutants. The evolution of the wave profiles is registered by a multipoint velocity interferometer system for any reflector (VISAR). The resultant velocity profiles are noticeably different from those predicted by the classical pattern of detonation initiation and evolution under a shock wave action.

The paper presents the results of radiation monitoring of gray forest soils of reference agricultural plots of the Vladimir region, conducted in 2011 and 2016. The study established background values of specific activities of the studied radionuclides in the soils of reference sites. According to the density of contamination of the arable horizon of soils 137Cs and 90Sr, the level of the ecological situation was determined, which made it possible to attribute the soils of all reference areas of the region to uncontaminated territories suitable without restrictions for agricultural use. The power of the exposure dose of gamma radiation of soils and the contribution of 40K and 137Cs to the formation of the gamma background of soils are established. Correlation ana-lysis determined the influence of individual physical and chemical properties of soils on the behavior and distribution of radionuclides in the soil and the relationship between the radionuclides themselves. Based on the values of the specific activity of 137Cs and 90Sr in plant products grown on the soils of reference sites in 2011 and 2016, rows of cultivated plants were constructed, with a decreasing ability to accumulate these radionuclides from the soil. All grown plant products for all types of crops fully met the sanitary and hygienic standards required to limit the content of 137Cs and 90Sr in plant feeds (green mass, straw and grain) and food products (apples). According to the transition coefficients, it was found that the process of transition of 90Sr from soil to plants of all kinds proceeded more intensively than the transition of 137Cs. The calculated coefficients of linear correlation between the values of the specific activity of 137Cs and 90Sr in soils and plants revealed the strength and nature of their dependencies.

An approach is proposed which makes it possible to lower the silicon melt infiltration temperature in the fabrication of silicon carbide/zirconium diboride matrix ceramic composites via the formation of a silicon–yttrium low-temperature eutectic. Using thermodynamic calculations, we have substantiated the addition of yttrium to a siliciding agent and demonstrated its advantages. Silicon melt infiltration into composites has been carried out for the first time at a temperature below the melting point of silicon, which has ensured a decrease in the degree of carbon fiber degradation, while allowing the matrix to retain high density and uniformity.

Министерство науки и высшего образования Российской Федерации Российское химическое общество им.Д.И.Менделеева Секция по химической термодинамике и термохимии Научного совета РАН по физической химии Сибирское Отделение Российской Академии Наук Институт неорганической химии им.А.В.Николаева СО РАН

In the present study, molecular dynamic simulations of high-velocity impact of 3C-SiC nanorod in a wide range of velocities with a rigid wall, were performed. The influence of different types of artificial defects in the nanorod on the ability to accumulate impact energy was investigated.

The results of radiation monitoring of sod-podzolic soils of reference agricultural plots of the Ivanovo region, conducted in 2014 and 2021, are presented. Background values of the specific activities of the studied radionuclides in the soils of reference sites have been established. According to the pollution density of the arable horizon of soils 137Cs and 90Sr, the level of the ecological situation was determined, which made it possible to attribute the soils of all reference areas of the region to uncontaminated territories suitable without restrictions for agricultural use. The power of the exposure dose of gamma radiation of soils and the contribution of 40K and 137Cs to the formation of the gamma background of soils were determined. Correlation analysis determined the influence of individual physical and chemical properties of soils on the behavior and distribution of radionuclides in the soil and the relationship between the content of the radionuclides themselves. Based on the values of the specific activity of 137Cs and 90Sr in plant products grown in 2014 and 2021, rows of cultivated plants with a decreasing ability to accumulate these radionuclides from the soil were constructed. All grown plant products of all types of crops fully met the veterinary standards required to limit the content of 137Cs and 90Sr in plant feeds (green mass, straw and feed grain). The coefficients of accumulation and transition of 137Cs and 90Sr from soil to plants are calculated. The coefficients of linear correlation between the values of the specific activity of 137Cs and 90Sr in soils and plants revealed the strength and nature of these dependencies.