Підвищення якості контуру «літак–система автоматичного керування»

This article deals with model based approach to mathematical modeling process of an aircraftflight control system. Analysis of emergency situations depend on phases of flight is done. Application ofmodern model based technologies for automatic flight control systems development is considered. Theprogram for aircraft-automatic flight control system control loop simulation and visualization is developed.Improvement of the automatic flight control system characteristics is showed. Availability of practicalapplication of developed program in aerospace scope is considered. Use of the mentioned approachallows to facilitate automatic flight control system development, analyze and certification processПредставлен модельно-ориентированный подход к процессу математического моделирования законов системы автоматического управления. Выполнен анализ аварийных ситуаций в зависимости от этапа полета. Рассмотрено применение современной модельно ориентированной технологии разработки законов системы автоматического управления. Разработана программа моделирования и визуализации контура самолет-система автоматического управления. Показано улучшение точности выдерживания параметров системы автоматическогоуправления. Рассмотрена возможность практического применения разработанной программы в авиационнойотрасли. Использование указанного подхода позволит сократить время на разработку, анализ и сертификациюсистемы автоматического управленияПредставлено модельно-орієнтований підхід до процесу математичного моделювання законів системи автоматичного керування. Виконано аналіз аварійних ситуацій в залежності від етапу польоту. Розглянуто використання сучасної модельно-орієнтованої технології розробки законів системи автоматичного керування. Розроблено програму моделювання і візуалізації контуру літак-система автоматичного управління. Показано поліпшення точності витримування параметрів системи автоматичного керування. Розглянуто можливість практичного застосування розробленої програми в авіаційній галузі. Використання вказаного підходу дозволить скоротити час на розробку, аналіз і сертифікацію системи автоматичного керуванн

The crystal growth and properties of novel magnetic double molybdate RbFe5_{5}(MoO4_{4})7_{7} with mixed Fe3+^{3+}/Fe2+^{2+}states and 1D negative thermal expansion

Single crystals of new compound RbFe$_5$(MoO$_4$)$_7$ were successfully grown by the flux method, and their crystal structure was determined using the X-ray single-crystal diffraction technique. The XRD analysis showed that the compound crystallizes in the monoclinic space group P21/m, with unit cell parameters a = 6.8987(4), b = 21.2912(12) and c = 8.6833(5) Å, β = 102.1896(18)°, V = 1246.66(12) Å$^3$, Z (molecule number in the unit cell) = 2, R-factor (reliability factor) = 0.0166, and T = 293(2) K. Raman spectra were collected on the single crystal to show the local symmetry of MoO$_4$ tetrahedra, after the confirmation of crystal composition using energy dispersive X-ray spectroscopy (EDS). The polycrystalline samples were synthesized by a solid-state reaction in the Ar atmosphere; the particle size and thermal stability were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analyses. The compound decomposes above 1073 K in an Ar atmosphere with the formation of Fe(III) molybdate. The thermal expansion coefficient along the c direction has the value α = −1.3 ppm K$^{−1}$ over the temperature range of 298–473 K. Magnetic measurements revealed two maxima in the magnetization below 20 K, and paramagnetic behavior above 50 K with the calculated paramagnetic moment of 12.7 μB per formula unit is in good agreement with the presence of $_3$Fe$^{3+}$ and $_2$Fe$^{3+}$ in the high-spin (HS) state. The electronic structure of RbFe5(MoO4)7 is comparatively evaluated using X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations

Ferromagnetic HfO2/Si/GaAs interface for spin-polarimetry applications

In this letter, we present electrical and magnetic characteristics of HfO2-based metal-oxide-semiconductor capacitors (MOSCAPs), along with the effect of pseudomorphic Si as a passivating interlayer on GaAs(001) grown by molecular beam epitaxy. Ultrathin HfO2 high-k gate dielectric films (3–15 nm) have been grown on Si/GaAs(001) structures through evaporation of a Hf/HfO2 target in NO2 gas. The lowest interface states density Dit at Au/HfO2/Si/GaAs(001) MOS-structures were obtained in the range of (6−13)×101

Constructing g-C3N4/Cd1−xZnxS-Based Heterostructures for Efficient Hydrogen Production under Visible Light

Two types of photocatalysts, 1%Pt/Cd1−x Znx S/g-C3 N4 (x = 0.2–0.3) and Cd1−x Znx S/1% Pt/g-C3 N4 (x = 0.2–0.3), were synthesized by varying the deposition order of platinum, and a solid solution of cadmium and zinc sulfides onto the surface of g-C3 N4. The characterization of photo-catalysts showed that, for 1%Pt/Cd1−x Znx S/g-C3 N4, small platinum particles were deposited onto a solid solution of cadmium and zinc sulfides; in the case of Cd1−x Znx S/1%Pt/g-C3 N4, enlarged platinum clusters were located on the surface of graphitic carbon nitride. Based on the structure of the photocatalysts, we assumed that, in the first case, type II heterojunctions and, in the latter case, S-scheme heterojunctions were realized. The activity of the synthesized samples was tested in hydrogen evolution from triethanolamine (TEOA) basic solution under visible light (λ = 450 nm). A remarkable increase in hydrogen evolution rate compared to single-phase platinized 1%Pt/Cd1−x Znx S photocat-alysts was observed only in the case of ternary photocatalysts with platinum located on the g-C3 N4 surface, Cd1−x Znx S/1%Pt/g-C3 N4. Thus, we proved using kinetic experiments and characterization techniques that, for composite photocatalysts based on Cd1−x Znx S and g-C3 N4, the formation of the S-scheme mechanism is more favorable than that for type II heterojunction. The highest activity, 2.5 mmol H2 g−1 h−1, with an apparent quantum efficiency equal to 6.0% at a wavelength of 450 nm was achieved by sample 20% Cd0.8 Zn0.2 S/1% Pt/g-C3 N4. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This work was supported by the Ministry of Science and Higher Education of the Russian Federation within the governmental order for Boreskov Institute of Catalysis (project AAAA-A21-121011390009-1) and was also funded by the Russian Foundation for Basic Research (project No. 20-33-70086). A.S.V. and I.A.W. thank Minobrnauki research project FEUZ-2020-0059 for financial support

Rare-earth-containing magnetic liquid crystals

Rare-earth-containing metallomesogens with 4-alkoxy-N-alkyl-2- hydroxybenzaldimine ligands are reported. The stoichiometry of the complexes is [Ln(LH)3(NO3)3], where Ln is the trivalent rare-earth ion (Y, La, and Pr to Lu, except Pm) and LH is the Schiff base. The Schiff base ligands are in the zwitterionic form and coordinate through the phenolic oxygen only. The three nitrate groups coordinate in a bidentate fashion. The X-ray single- crystal structures of the nonmesogenic homologous complexes [Ln(LH)3(NO3)3], where Ln = Nd(III), Tb(III), and Dy(III) and LH = CH3OC6H3(2-OH)CH=NC4H9, are described. Although the Schiff base ligands do not exhibit a mesophase, the metal complexes do (SmA phase). The mesogenic rare-earth complexes were studied by NMR, IR, EPR, magnetic susceptibility measurements, X-ray diffraction, and molecular modeling. The metal complexes in the mesophase have a very large magnetic anisotropy, so that these magnetic liquid crystals can easily be aligned by an external magnetic field

Memristors Based on Many-Layer Non-Stoichiometric Germanosilicate Glass Films

Nonstoichiometric GeSixOy glass films and many-layer structures based on them were obtained by high-vacuum electron beam vapor deposition (EBVD). Using EBVD, the GeO2, SiO, SiO2, or Ge powders were co-evaporated and deposited onto a cold (100 °C) p+-Si(001) substrate with resistivity ρ = 0.0016 ± 0.0001 Ohm·cm. The as-deposited samples were studied by Fourier-transformed infrared spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. A transparent indium–tin–oxide (ITO) contact was deposited as the top electrode, and memristor metal–insulator–semiconductor (MIS) structures were fabricated. The current–voltage characteristics (I–V), as well as the resistive switching cycles of the MIS, have been studied. Reversible resistive switching (memristor effect) was observed for one-layer GeSi0.9O2.8, two-layer GeSi0.9O1.8/GeSi0.9O2.8 and GeSi0.9O1.8/SiO, and three-layer SiO2/a–Ge/GeSi0.9O2.8 MIS structures. For a one-layer MIS structure, the number of rewriting cycles reached several thousand, while the memory window (the ratio of currents in the ON and OFF states) remained at 1–2 orders of magnitude. Intermediate resistance states were observed in many-layer structures. These states may be promising for use in multi-bit memristors and for simulating neural networks. In the three-layer MIS structure, resistive switching took place quite smoothly, and hysteresis was observed in the I–V characteristics; such a structure can be used as an “analog” memristor

Quantifying the surface modification induced by the argon cluster ion bombardment of KGd(WO4)2: Nd single crystal

The damage in an inorganic single crystal surface caused by gas cluster ion bombardment is still an open issue. In this work, the influence of the kinetic energy per atom in the clusters E/N on the physicochemical structure of KGd(WO4)2:Nd single crystals was evaluated using XPS, Raman spectroscopy and XRD techniques. The highenergy mode with an energy per atom in the cluster E/N of about 100 eV provides a sufficient sputtering efficiency, while the low-energy mode with an energy of a several eV provides the minimal surface damage. The results revealed no substantial damage to the subsurface crystal structure after the cluster bombardment processing. Nevertheless, the unexpected increase in the relative concentration of O atoms by 12% and depletion of K atoms by a factor of 2 in the subsurface layer of KGd(WO4)2:Nd crystals were detected. The features of surface sputtering of inorganic single crystals at different E/N-modes are discussed

Flux crystal growth and the electronic structure of BaFe12O19 hexaferrite

The barium hexaferrite, BaFe12O19, microcrystals were obtained by the flux crystal growth method and were characterized by XRD, SEM, and TEM methods. XPS measurements were carried out on a powder sample. The binding energy differences between the O 1s and cation core levels, ΔBa = BE(O 1s) – BE(Ba 3d5/2) and ΔFe = BE(O 1s) – BE(Fe 2p3/2), were used to characterize the valence electron transfer on the formation of Ba–O and Fe–O bonds. The chemical bonding effects were considered on the basis of our XPS results measured for BaFe12O19 and the earlier published structural and XPS data for other Ba- or Fe-containing oxide compounds. The band structure of BaFe12O19 was calculated by spin-polarized DFT methods and compared to the valence band spectrum measured by the XPS method

Flux crystal growth and the electronic structure of BaFe12O19 hexaferrite

The barium hexaferrite, BaFe12O19, microcrystals were obtained by the flux crystal growth method and were characterized by XRD, SEM, and TEM methods. XPS measurements were carried out on a powder sample. The binding energy differences between the O 1s and cation core levels, ΔBa = BE(O 1s) – BE(Ba 3d5/2) and ΔFe = BE(O 1s) – BE(Fe 2p3/2), were used to characterize the valence electron transfer on the formation of Ba–O and Fe–O bonds. The chemical bonding effects were considered on the basis of our XPS results measured for BaFe12O19 and the earlier published structural and XPS data for other Ba- or Fe-containing oxide compounds. The band structure of BaFe12O19 was calculated by spin-polarized DFT methods and compared to the valence band spectrum measured by the XPS method