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Changes in the composition of the surface layer of Nevaflon polyvinylidene fluoride film after treatment in gas discharges of various types (glow, dielectric barrier, corona) have been studied. The influence of the discharge type on the kinetics of etching and surface modification of polyvinylidene fluoride is shown. It has been found that the plasma treatment of polyvinylidene fluoride leads to a change in the modified surface layer of the polymer. [ABSTRACT FROM AUTHOR]

Numerical studies on the effect of surface relaxation, namely, the equilibrium change in the interplanar distance, exerted on the values of the magnetic and energy characteristics of a Fe/Pt/Fe system have been performed. The contribution of spin-orbit coupling to the value of magnetic anisotropy energy is studied as a function of ferromagnetic film thickness. [ABSTRACT FROM AUTHOR]

In this paper we report on results of an investigation of a transparent mesh electrode in a wide wavelength range 550–2000 nm with low electrical resistance manufactured by laser ablation with using an aluminum film with a thickness of 30 pm on a polyimide substrate with a thickness of 20 μm. The method is implemented using a fiber ytterbium nanosecond laser with a wavelength of radiation 1064 nm. The structure we have obtained has a transmittance >50% in the designated spectrum range and the electrical resistance <1.5 Ω/sq. [ABSTRACT FROM AUTHOR]

The energy and magnetic properties of Fe/Cr/Fe and Fe/Pt/Fe systems are studied using the spin density functional theory and the VASP software. Calculated dependences of the total energy on the angle of the magnetic moment of atoms show the advantage of the perpendicular anisotropy of Fe/Cr/Fe for all considered Fe film thicknesses and surface orientations. A more complex dependence is observed for Fe/Pt/Fe, but easy-plane anisotropy predominates upon an increase in the iron film thickness. [ABSTRACT FROM AUTHOR]

Methods for fabrication of materials that simultaneously exhibit high transparency in the visible spectral range and radio shielding in a wide frequency band are considered. The main structures of such materials (multilayer coatings and mesh structures) are analyzed and compared, and several technological procedures are considered. It is shown that optimization of the thickness and chemical composition of multilayer coatings and geometrical parameters of mesh structures can significantly improve their properties. Promising structures are proposed to obtain an optical transmission coefficient of 90–98% and a radio shielding coefficient of 50–65 dB. [ABSTRACT FROM AUTHOR]

A solution to the problem of design and technological optimization (DTO) of resonant-tunneling diodes (RTDs) based on the electrical parameters of nonlinear frequency converters (FCs) is proposed to ensure their reliability in given operating conditions. A software package has been developed that makes it possible to perform an analysis of the reliability of FC microwave radio signals based on RTDs and to carry out DTO of the electrical characteristics of the FC in order to ensure reliability under specified operating conditions The developed software complex is tested on a wideband RTD-based balanced microwave frequency mixer. It was revealed that performing DTO on the mentioned mixer allows us to increase its gamma-percentage resource by 7.5 times, which proves that DTO is a perspective way to ensure RTD-based FC reliability. [ABSTRACT FROM AUTHOR]

An investigation is performed of substitutional adsorption in an Fe/Ag system using two approaches: variational spin density functional with allowance for temperature effects and ab initio using VASP. The dependence of the energy of adsorption and magnetic moment on the orientation of the face and the fraction of adatoms in the film is obtained. The strong effect of mixing and the energy advantage of forming a sandwich structure are revealed. [ABSTRACT FROM AUTHOR]

The potential of construction of machine learning models was considered as applied to water level forecasting in mountain river reaches in Krasnodar Krai based on observation data on water levels at automated hydrological complexes of the Automated System of Flood Conditions Monitoring in Krasnodar Krai. The study objects were two mountain rivers in Krasnodar Krai―the Pshish and Mzymta. These rivers flow in different natural conditions and differ in their water regimes and the character of lateral inflow in the reaches under consideration. The study focused on three widely used machine learning architectures: regression model of decision trees M5P, gradient boosting of decision trees XGBoost, and artificial neural network based on multilayer perceptron. The forecast quality was evaluated for lead time from 1 to 20 h; variations for rivers with different water regimes and the potential of the examined models as applied to operational forecasting are discussed. The optimal lead time for the Pshish river was found to be 15–18 h (with S/σΔ varying within 0.38–0.39 for XGBoost model); the simulation quality for the Mzymta river is evaluated as good; however, the necessary forecast efficiency is not attained (at the lead time of 5 h, we have S/σΔ = 0.87 for MLP model). The obtained results allow the machine learning models to be regarded as acceptable for short-term hydrological forecasting based on high-frequency water level observation data. [ABSTRACT FROM AUTHOR]

The solution of the resonant-tunneling diode-based subharmonic microwave radio signals mixer's reliability in given operating conditions are presented. The goal was achieved by design and technological optimization of the device's electrical parameters. The optimal combination of the mixer's electrical parameters was determined by a software suite developed by the authors. The gamma-percentage resource was increased by 1.49 times after optimization. [ABSTRACT FROM AUTHOR]

The problem of reinforcing the mirror surfaces of space-based astronomical optics and their protection against external factors is discussed. To solve this problem, the possibility of the deposition of diamond-like coatings onto them is considered. Using mirrors with Al and Cu coatings as an example, it has been experimentally demonstrated that the pulsed laser deposition of a carbon layer with a thickness of 30 nm onto them leads to an increase in the surface hardness by 25 and 100%, respectively. It has been established that the reinforcing coating has no effect on the shape deviations of mirrors and decrease their surface roughness. In this case, the reflection factor appreciably decreases in the visible region (400–780 nm), whereas its decrease in the infrared region (above 780 nm) is no more than 5%. [ABSTRACT FROM AUTHOR]

A technique for assessing the quality of AlAs/GaAs nanoscale resonant-tunneling heterostructures from the viewpoint of their resistance to diffusion destruction is developed. The diffusive spreading of AlAs/GaAs heterostructure layers is revealed by infrared (IR) spectral ellipsometry and the Al and Si diffusion coefficients in GaAs are determined. [ABSTRACT FROM AUTHOR]

The article presents a study on the application of infrared (IR)-spectroscopic ellipsometry in studying the changes of a polytetrafluoroethylene (PTFE) sample in terms of roughness, thickness, and chemical structure. It says that the ellipsometric model was made with the construction of the PTFE absorption peaks based on the parameters of the oscillators. The results showed that the thickness was reduced due to the direct-current discharge.