Table of contents

The International Conference PhysicA.SPb was held 1-3 November 2016 in Saint-Petersburg, Russia. The Conference continues the tradition of Saint-Petersburg Seminars on Physics and Astronomy originating from mid-90s. Since then PhysicA.SPb maintains both scientific and educational quality of contributions delivered to the young audience. This is the main feature of the Conference that makes it possible to combine the whole spectrum of modern Physics and Astronomy within one event.

PhysicA.SPb/2016 has brought together about 300 students, young scientists and their colleague professors from many universities and research institutes across whole Russia as well as from Belarus, Ukraine, Germany, Finland, Netherlands, and France. Oral and poster presentations were combined into well-defined sections among which one should name Astronomy and Astrophysics, Optics and spectroscopy, Physics of ferroics, Nanostructured and thin-film materials, Mathematical physics and numerical methods, Devices and materials for the THz and microwave ranges, Biophysics, Optoelectronic devices, Surface phenomena, Physics and technology of energy conversion, Plasma physics, hydrodynamics and aerodynamics, Nuclear and elementary particle physics, Impurities and defects in solids, and Physics of quantum structures.

This issue of the Journal of Physics: Conference Series presents the extended contributions from participants of PhysicA.SPb/2016 that were peer-reviewed by expert referees through processes administered by the Presiders of the Organising and Programme Committees to the best professional and scientific standards. This was made possible by the efforts of the Sectional Editors of this Issue: Prof. Petr Arseev (Lebedev Physical Institute), Prof. Yuri Kusraev (Ioffe Institute), Prof. Alexander Ivanchik (Ioffe Institute), Prof. Polina Ryabochkina (Ogarev Mordova State University), Dr. Karina Litvinova (Aston University), Dr. Nikolay Bert (Ioffe Institute), Dr. Yana Kuznetsova (Ioffe Institute), Dr. Prokhor Alekseev (Ioffe Institute), Dr. Mikhail Dunaevskii (Ioffe Institute), Dr. Alexandra Kalashnikova (Ioffe Institute) and Prof. Dmitry Khokhlov (Moscow State University).

The Editors: Nikita S. Averkiev, Sergey A. Poniaev and Grigorii S. Sokolovskii

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The deviations in orbital motion of the asteroid-meteoroid 2008 TC3 and the asteroid, which subsequently became the Chelyabinsk meteorite, under radiation pressure influence were calculated. These celestial objects are of special interest for investigation, since due to the close encounters with the Earth their orbits had dramatically changed, which resulted in their downfall. Calculations were made for several values of albedo of the asteroids in order to compare the extent of deviations. Obtained results allowed estimating the effect of solar radiation pressure depending on changes of surface reflectance of the objects.

The aim of this paper is to represent the results of a structured fractal analysis of gravitational and topographical parameters of Mars on the basis of data obtained from the space missions. To analyze Martian fractal structures the observations from the data received from boards of the space missions including «Mars Global Surveyor» has been used. The models of relief and Mars' gravitational field have been constructed on the basis of harmonic analysis of the expansion in spherical functions of the satellite observations data. As a result, fractal dimensions of Martian relief's anomalies and Mars' gravitational potential by longitude and latitude have been determined. Mean values of the fractal dimensions $\bar{D}$ have been obtained as well: mean fractal dimensions of Martian topographic model by latitude $\bar{D}=0.86$, by longitude $\bar{D}=0.88$; mean fractal dimensions of Martian gravitational potential anomalies by latitude $\bar{D}=1.06$, by longitude $\bar{D}=1.092$.

Discrete variable absorption components in the RZ Psc spectrum are studied. Two hypothesis of their formation are considered. The effective star radiation scattering computation method is presented. The resonance scattering in both cases is modeled. The model spectra are reviewed and analyzed. The conclusion about the possible reasons of the observed spectra formation is made.

The structure of steady one-dimensional shock waves in partially ionized interstellar gas is studied. The model is constructed of so called C-type shocks where the physical parameters characterizing the flow change continuously at the shock front. We present our first results of the modelling of C-type shocks. The model will be employed to study molecular line emission from interstellar shocks, in particular, maser emission.

The persistent X-ray pulsar OAO 1657-415 is associated with a wind-fed High Mass X-ray Binary system and shows a peculiar spin evolution. On a timescale of more than 30 years it is observed to experience a regular spin-up which is superposed on episodic and chaotic variations of the period at a very high rate. We explore a possibility to explain the spin evolution of the pulsar in terms of Magnetic Levitation Accretion scenario in which the neutron star captures material from a magnetized stellar wind of its massive companion and accretes matter from a non-Keplerian magnetized disk (Magnetic Levitating disk or ML-disk). We show this scenario to be applicable if the magnetic field in the wind at a distance of binary separation lies in the interval 20 – 70 mG.

A kinetic model of the mirror instability in highly non-equilibrium anisotropic relativistic plasma is presented. The growth rate is derived for long-wavelength compressible magnetic perturbations in a magnetized collisionless plasma with an anisotropic pressure of the relativistic component. The mirror-type mode perturbations of the magnetic field are growing for the wave vectors preferentially directed transverse to the mean magnetic field. The mirror instability may occur in the vicinity of relativistic particle accelerators in the interstellar and intergalactic media.

The evolution of the inclination angle and precession damping is considered. It is assumed that the neutron star consists of 3 freely rotating components: the crust and two core components, one of them contains pinned superfluid vortices. We suppose that each component rotates as a rigid body. Also the influence of the small-scale magnetic field on the star's breaking process is examined. Within the framework of this model the star simultaneously can have glitch-like events combined with long-period precession (with periods 10 – 10⁴ years). It is shown that the case of the small quantity of pinned superfluid vortices seems to be more consistent with observations.

Nuclear interactions of protons and helium ions accelerated in solar flares with solar atmosphere are simulated using Geant4 toolkit.The long term average spectrum of solar cosmic rays is taken from measurements of cosmogenic isotopes production in lunar soil. Solar atmospheric profiles of ⁶Li, ⁷Li and ¹⁴C generation are calculated. These isotopes outflow into interplanetary space with coronal mass ejections and following implantation into lunar rocks are considered to explain anomaly isotopic composition of thin lunar surface layer. Also, generated energy spectra and angular distributions of neutrons, gamma- and x-rays in space are presented for different spectra of solar flares.

The distribution function for generalized polytropic models has been used to construct a series of numerical models of anisotropic disks. It has been shown with the help of simulation that such systems are unstable with respect to bar formation at any degree of radial elongation of star orbits. The result is completely at variance with the conclusions of earlier works, where similar models were studied. The pattern speeds and amplitudes of the forming bar were found, and the initial distributions of orbit precession rates were calculated. Such systems have been shown to fulfill all conditions for the onset of radial orbit instability, responsible for the formation of a slow bar.

The goal of this work is to investigate the effects of chemical composition of heat blanketing envelopes of neutron stars on their thermal states and thermal evolution. To this purpose, we employ newly constructed models of the envelopes composed of binary ion mixtures (H–He, He–C, C–Fe) varying the mass of lighter ions (H, He or C) in the envelope. The results are compared with those calculated using the standard "onion-like" envelope. For illustration, we apply these results to estimate the internal temperature of the Vela pulsar and to study cooling of neutron stars. We show that uncertainties in the chemical composition of the envelopes can lead up to ~ 2.5 times uncertainty of the internal temperature of the star which significantly complicates theoretical reconstruction of the internal structure of cooling neutron stars from observations of their thermal surface emission.

We report the results of a simultaneous analysis of the archival Suzaku and Swift X-ray data of the γ-ray pulsar J1932+1916 field. A point-like source and diffuse emission around it were detected at the γ-ray position of the pulsar. Their spectral properties allow one to suggest that Suzaku and Swift detected the X-ray counterpart of PSR J1932+1916. Using of the interstellar absorption–distance relations, we constrain the distance to the pulsar in the range of 2–6 kpc. We also discuss a possible association of the pulsar with the supernova remnant G54.4–0.3.

This work is devoted to a description of thermodynamic properties of Coulomb crystals which are expected to form in white dwarf interiors. Effects of magnetic field, isotopic impurities, polarization of the electron background and crystal lattice type on the thermal evolution of white dwarfs are discussed. It is shown that the electron polarization could play a noticeable role in the cooling process. While other parameters in concern do not make a significant impact.

In this paper the problem of the lunar center of mass relative to the center of its figure determination on the basis of space observations is considered, since the Moon is the most studied celestial object and there is a complete database on it. The future prospects for lunar laser ranging and radio interferometry require development of adequate theoretical support for modern technologies. The aim of these studies is the distances' measurement between the Moon and the Earth with an accuracy of 1 mm. Thus, determination of the lunar center of mass position, represented in this paper, and development of the selenocentric system will allow to solve the above mentioned problem more accurately and reliably. The new values of the lunar center of mass relative to its center of figure in orthogonal selenographic coordinate system Δξ, Δη, Δζ have been determined; they are: -1.75, -0.75, 0.11 km respectively.

The problem of Cosmic Ray (CR) origin and acceleration is a widely discussed problem of modern astrophysics. It is considered that most likely CR sources are supernova remnant shock waves. One of the methods to study particle injection and acceleration by shock waves is a particle-in-cell computer simulation. In this paper we present results of shock wave simulations based on our self-developed implicit particle-in-cell code. First, we test the code with the well-known two stream and Weibel instabilities and second, simulate shock waves in plasma with different particle composition. Using the obtained results we study the process of charged particle acceleration at the shock front.

The consistent interpretation of the multiwavelength pulsar wind nebula observations require studying of interaction of a relativistic pulsar wind with the interstellar medium (ISM). In this paper we present the results of the Monte-Carlo modeling of the test particle propagation in a pulsar wind nebula beyond the pulsar wind termination shock. The non-thermal electron-positron spectra in the pulsar wind nebula and in the vicinity of the pulsar bow shock are derived in case of the supersonic proper motion of the pulsar through the ISM. The synchrotron emission images of the pulsar wind nebula at photon energies in the far ultraviolet and soft X-ray ranges are constructed. We discuss a possible interpretation of the recent HST and Chandra observations of the pulsar wind nebula associated with the PSR J0437-4715 in the frame of the model.

In this article a technique for the bioelectrical signals acquisition by means of the capacitive sensors is described. A feedback loop for the ultra-high impedance biasing of the input instrumentation amplifier, which provides receiving of the electrical cardiac signal (ECS) through a capacitive coupling, is proposed. The mains 50/60 Hz noise is suppressed by a narrow-band stop filter with an independent notch frequency and quality factor tuning. Filter output is attached to a ΣΔ analog-to-digital converter (ADC), which acquires the filtered signal with a 24–bit resolution. Signal processing board is connected through universal serial bus interface to a personal computer, where ECS in a digital form is recorded and processed.

This article describes the development of the experimental setup for measuring the cell membrane electrical potential by Double -Sucrose-Gap Technique. The double-gap isolation method allows the simultaneous measurement of electrical activity and tension output from contracting segments of muscle fibers. This technique has been widely used as a convenient tool for recording of the membrane activities from myelinated or unmyelinated nerves and muscle preparations. This device can be an effective way to provide undergraduate biomedical engineering students with invaluable experiences in neurophysiology. The installation design and its main characteristics are described. The advantages of the described device are the simplicity of the experiment, relatively low cost, the possibility of long-term experiment.

Fabrication and investigation of specialized Pt-C single nanowhisker probes are carried out for high-precision study of objects with organic and inorganic nature in liquids by atomic force microscopy. The best modes and buffered media were revealed on calibration lattice TGQ1 choosing as reference inorganic structure. Preliminary results of the study of the structure of bacteria E.Coli in the native state were received in the PBS liquid. Fixation of the bacteria was performed on agar-agar with a mass fraction of 1.8%. The significant improvement of image contrast and resolution was found when using nanowhisker probes compare to standard Si tips.

Temperature influences all biochemical processes, in particular, excitation-contraction coupling(ECC) in cardiac cells. In this work we propose a theoretical explanation of temperature effects on an isolated ryanodine receptor calcium release channel (RyR channel) within the electron-conformational (EC) model. We show that the EC model with an Arrhenius-like temperature dependence of the "internal" and "external" frictions and a specific thermosensitivity of the tunnelling "open ↔ closed" transitions can provide both qualitative and quantitative description of the temperature effects for isolated RyR channels. Interestingly that a small change of the activation energy for the "internal" friction can make an ion channel either heat-inhibited or heat-activated while the "external" friction doesn't play a key role in temperature sensitivity: neglect of "external" friction doesn't change the channel's temperature sensitivity qualitatively.

Interaction of synthetic alkaloid of isoquinoline series, which is an analogue of the biologically active compound papaverine, was studied by spectral, microcalorimetric, optical and hydrodynamic methods at different ionic strengths of medium. It was found that the investigated compound may interact with DNA in various ways depending on the ratio of ligand - DNA concentrations and ionic strength of solution (μ). When μ = 0.001, indole-papaverine intercalates into the double helix of DNA. The increase of μ resulted in a decrease of the affinity of the compound to DNA and a change its binding method.

The article gives an overview of present results of a study of the luminescence of living plants in room temperature and also the luminescence of green leaves in a living state and taken from the parent plant. The analysis of obtained results allows to conclude that the photoluminescence spectra for green leaves in all cases represent the two closely spaced bands. Temporal intensity of photoluminescence of green leaves of plants were studied.

Paper presents results of calculation, electromagnetic modelling and measurements of manufactured antenna system on planar Yagi-Uda elements and microstrip coupler. System has summary and subtract modes. Center frequency of system is 1532 MHz with 96 MHz bandwidth. Gain of system is 8 dB in main lobe direction (in-phase mode) and 5 dB (antiphase mode).

Nonlinear dynamics of a microwave optoelectronic oscillator was investigated for the first time with the use of time series analysis. The detailed study of the generated microwave waveforms showed a route from stable monochromatic oscillations to noise through a series of bifurcations. The oscillator demonstrated the periodic and chaotic dynamics in the intermediate regimes of self-generation. Peculiarities of the signals and their spectra for the chaotic and noise regimes were found. The chaotic and noise dynamics were proven with the Grassberger-Procaccia method.

The authors of the paper describe the method of water content measuring using microwaves for oil transported by pipeline. There is a description of the experimental stand used for the determination of water content of oil by using microwaves and of the methodology of the planned experiments. There is also an algorithm for the mass concentration of water in gas-saturated water-oil emulsions determination according to the results of experimental research on the experimental stand.

A new approach allowing to improve frequency-selective properties for a fixed order of N filter is suggested. In all the studies, conducted with the help of numerical electrodynamic analysis of 3D models of microstrip filters based on a multimode resonator, the same substrate with dielectric constant ε=2.8 and thickness h=2 mm (material - FLAN) was used in calculations. The central bandpass frequency of microwave structures f₀≈1.4 GHz was registered and as well as relative bandwidth Δf/f_o≈80%. The strip conductor of central multimode resonator in six studied filters of the sixth and eighth orders has the shape of an irregular meander being electromagnetically connected with four single-mode resonators, a pair of which is located to the left of it, and the other pair is to the right. It is shown that in single-mode quarter-wave resonators building-up the number of portions of identical parallel strip conductors, connected to a screen at one end and connected with each other by a strip conductor jumper, can increase the power of suppression at low-frequency stop band by more than 15 dB, as well as near high-frequency slope of passband by more than 10 dB. Therefore, the level of maximums of return losses in the passband of wideband bandpass filter ranges within a few dB.

Construction of microstrip bandpass filters is suggested on the basis of 2D electromagnetic crystal consisting of P horizontal and K vertical rows of resonators. Adjacent vertical rows of resonators are connected by additional m_K-1 resonators arranged above and below the outside 2D crystal. Parametric synthesis of six bandpass filters based on crystals with the dimension of 1×2, 2×2, 2×3, 3×1, 3×2 and 3×3 was conducted with use of electrodynamic numerical analysis of 3D models in studied constructions. While calculating substrates with relative permittivity ε=80, h=1 mm thick were used, in this connection, center frequency of bandwidth was registered as follows - f₀≈1.0 GHz, as well as their relative bandwidth Δf/f₀≈20%. High frequency-selective properties of the filters are connected not only with the increase of their N order, but also with the presence of amplitude-frequency characteristics of power attenuation poles located near the bandwidth.

A theoretical model of ferrite film magnonic crystals made with periodic metallization of the film surface was developed taking into account finite metal conductivity. Results show that finite metal conductivity affects to the insertion losses. The theoretical calculations have a good agreement with the experimental results.

Resonant properties of a spin-wave optoelectronic single-loop resonator are experimentally investigated. The resonator is composed of a spin-wave delay line and a microwave photonic delay line based on a single-mode optical fiber. This circuit is equivalent to a comb filter. The microwave photonic delay line provides the main contribution to the delay time and defines mostly the free spectra range (FSR). The spin-wave delay line realizes the reconfiguration of resonator bandwidth and its frequency tuning. Influences of delay time and amplifier gain coefficient on quality-factor are analyzed.

An application of Doppler broadening of annihilation line spectroscopy to samples of beryllium bronze DIN-CuBe2 exposed to sandblasting is presented in performed studies. It is familiar that sandblasting introduces open-volume defects. Samples were sandblasted under different pressure for 1 minute using 110 μm particles of Al₂O₃. For a non-defected sample the constant value of S-parameter was detected. In the cases of sandblasted samples, S-parameter decreased when the depth enhanced. In our studies the thicknesses of defected zones were determined (it was c.a. 30 μm for a sample blasted under pressure of 1 bar and 110 μm – for 5 bar), and it was also observed that if sandblasting pressure is higher the defected zone is larger.

The lattice parameters a, c of iron borate FeBO₃ polycrystals have been measured in the temperature range 25–600°C by the X-ray diffraction method. The thermal expansion coefficients α are calculated from the measured values of the parameters. A substantial anisotropy of the thermal expansion is found. It is shown that the thermal expansion coefficient α_c along the c axis is greater than the thermal expansion coefficient α_a in a plane perpendicular to this axis. By X-ray peak profile analysisthe crystallite size was estimated from Scherrer's formula. We have also investigated the temperature dependence of crystallite size in FeBO₃.

We present a stable random matrix approach to the old standing problem of the boson peak in amorphous dielectrics (glasses). In this paper, we consider a two-dimensional case. We show that in the 2d case the boson peak in the density of vibrational states appears in a natural way in different random matrix models similar to the 3d case. Changing the parameters of random matrices one can shift the boson peak to higher or to lower frequencies depending on the strength of disorder in the model. In all investigated cases the position of the boson peak is correlated with the Young modulus of the lattice.

Systems of parametrical lattice Boltzmann equations (LBE's) are considered. The formulae for the apparent viscosity for the general representation of these systems is obtained by Chapman — Enskog asymptotic expansion on Knudsen number. Obtained expression represents viscosity as a function of the relaxation parameter and parameter of the LBE's. Necessary stability conditions in form of inequalities are derived from the non-negativity condition of the apparent viscosity. The validity of the stability conditions are demonstrated by the solution of lid-driven cavity flow problem.

Explicit finite-difference schemes for the linear advection equations are considered. The schemes may be used in the advective step of the splitting method for the kinetic equations. The time derivative is approximated with first order by special asymmetric approximation. Schemes from first to fourth orders of approximation on space are constructed. Stability analysis is realized by von Neumann method. Stability criteria in the form of inequalities on Courant parameter are obtained. As it is demonstrated, obtained schemes demonstrate better stability properties in cases of high order asymmetric approximations in comparison with well-known explicit schemes.

One of the technological challenges for hydrogen materials science (including the ITER project) is the currently active search for structural materials with various potential applications that will have predetermined limits of hydrogen permeability. One of the experimental methods is thermal desorption spectrometry (TDS). A hydrogen-saturated sample is degassed under vacuum and monotone heating. The desorption flux is measured by mass spectrometer to determine the character of interactions of hydrogen isotopes with the solid. We are interested in such transfer parameters as the coefficients of diffusion, dissolution, desorption. The paper presents a thermal desorption functional differential equations of neutral type with integrable weak singularity and a numerical method for TDS spectrum simulation, where only integration of a nonlinear system of low order ordinary differential equations (ODE) is required. This work is supported by the Russian Foundation for Basic Research (project 15-01-00744).

The arrowhead decomposition method (ADM) for the parallel solution of a block-tridiagonal system of linear equations is presented. The method consists in rearranging the initial linear system into an equivalent one with the "arrowhead" structure of the matrix. It is shown that such a structure provides a good opportunity for parallel solving. The computational speedup of ADM with respect to the sequential matrix Thomas algorithm is analytically estimated based on the number of elementary multiplicative operations for the parallel and serial parts of the methods. A number of parallel processors required to reach the maximum computational speedup is found. A good agreement of the analytical estimations of the computational speedup and practically obtained results is observed.

In northern seas the gas temperature in the pipeline may be lower than the water-ice phase transition temperature, so the glaciation process must be considered. The coefficient smoothing method for the problem of glaciation of the cylinder immersed in seawater is considered. The model of glaciation process is presented as a problem for the linear heat equation in domain with unknown moving boundary. The method of solution is based on the transition to the Dirichlet problem for the nonlinear two-dimensional heat equation in domain with fixed boundaries. The splitting method is applied to the solution of the problem for two-dimensional heat equation. Two approximations for the Dirac delta function are proposed. Calculation of uniform glaciation process was carried out with the using of nonlinear implicit finite-difference schemes. Time moments of the glaciation for different spatial layers are obtained. Results of calculations are compared with the results obtained by the front-tracking method.

We propose a new numerical method to determine the central charge of the conformal field theory models corresponding to the 2D lattice models. In this method, the free energy of the lattice model on the torus is calculated by the Wang-Landau algorithm and then the central charge is obtained from a free energy scaling with respect to the torus radii. The method is applied for determination of the central charge in the site-diluted Ising model.

Deep neural networks with a large number of parameters are a powerful tool for solving problems of pattern recognition, prediction and classification. Nevertheless, overfitting remains a serious problem in the use of such networks. A method of solving the problem of overfitting is proposed in this article. This method is based on reducing the number of independent parameters of a neural network model using the principal component analysis, and can be implemented using existing libraries of neural computing. The algorithm was tested on the problem of recognition of handwritten symbols from the MNIST database, as well as on the task of predicting time series (rows of the average monthly number of sunspots and series of the Lorentz system were used). It is shown that the application of the principal component analysis enables reducing the number of parameters of the neural network model when the results are good. The average error rate for the recognition of handwritten figures from the MNIST database was 1.12% (which is comparable to the results obtained using the "Deep training" methods), while the number of parameters of the neural network can be reduced to 130 times.

High-purity hydrogen is required for clean energy and a variety of chemical technology processes. Different alloys, which may be well-suited for use in gas-separation plants, were investigated by measuring specific hydrogen permeability. One had to estimate the parameters of diffusion and sorption to numerically model the different scenarios and experimental conditions of the material usage (including extreme ones), and identify the limiting factors. This paper presents a nonlinear mathematical model taking into account the dynamics of sorption-desorption processes and reversible capture of diffusing hydrogen by inhomogeneity of the material's structure, and also modification of the model when the transport rate is high. The results of numerical modelling allow to obtain information about output data sensitivity with respect to variations of the material's hydrogen permeability parameters. Furthermore, it is possible to analyze the dynamics of concentrations and fluxes that cannot be measured directly. Experimental data for Ta₇₇Nb₂₃ and V₈₅Ni₁₅ alloys were used to test the model. This work is supported by the Russian Foundation for Basic Research (Project No. 15-01-00744).

In this paper a wide-range equation of state for computer simulation of metal ablation by femtosecond laser pulses is proposed. The simulation results are compared with experimental data for several metals (Al, Au, Cu, Ni). A good agreement for numerical results with experimental data shows that this equation of state together with two-temperature hydrodynamic model can be employed for choosing laser parameters to receive better accuracy in simulation of metal ablation.

The efficiency of computer ECG analysis depends on the accurate detection of QRS-complexes. This paper presents an algorithm for QRS complex detection based of support vector machine (SVM). The proposed algorithm is evaluated on annotated standard databases such as MIT-BIH Arrhythmia database. The QRS detector obtained a sensitivity Se = 98.32% and specificity Sp = 95.46% for MIT-BIH Arrhythmia database. This algorithm can be used as the basis for the software to diagnose electrical activity of the heart.

Experimental study of the iodine nanoparticles effect on the optical and electrical properties of zeolite - based matrix nanocomposite materials has been carried out. Phase transitions in the nanocomposites under study have been found.

The paper examines the effect of doping with tungsten on switching in hydrated vanadium pentoxide films. The switching effect is associated with the metal-insulator transition in a vanadium dioxide channel that forms in the initial film due to the process of electrical forming (EF). Doping is carried out by the plasma immersion ion implantation method. It is shown that implanting small tungsten doses improves the switching parameters after EF. When implanting large doses, switching is observed without EF, and if EF is applied, the switching effect, on the contrary, disappears.

Liquid crystals are one of the most interesting materials for various applications. The article considers the influence of temperature to the phase change and the value of surface potential of 4'-n-octyl-4-p-cyanobiphenyl liquid crystal Langmuir monolayers. These parameters have a critical role in process of transfer monolayers to the solid substrate and for further using of them. It is shown that with increasing temperature of subphase leads to the monolayer of liquid crystal becomes isotropic and exhibits a gradual decrease in the surface potential in process of compression.

VO₂ switches with threshold voltages less than 2 V were fabricated. Synchronization between two oscillators based on VO₂ switches coupled through resistance and capacitance was investigated. For resistive coupling range of resistances in which synchronization appeared was defined and phase instability was observed. For capacitive coupling two synchronization modes were found. Simulation of changing of the relative phase for two oscillators in the case of capacitive coupling for both synchronization modes has been carried out. The relative phase variation range more than 310° was obtained.

The paper presents results of a study of indium-zinc oxide nanofibers sensitivity to ultraviolet radiation in the range 230-290 nm. Nanofibers are synthesized by electrospinning. It is shown that the largest increase in photoconductivity is observed at the indium to zinc concentration ratio of about 1:1.

The data on the growth peculiarities and physical properties of GaAs insertions embedded in AlGaAs nanowires grown on Si (111) substrates by Au-assisted molecular beam epitaxy are presented. It is shown that by varying of the growth parameters it is possible to form structures like quantum dots emitting in a wide wavelengths range for both active and barrier parts. The technology proposed opens new possibilities for the integration of direct-band A^IIIB^V materials on silicon platform.

This is a study of the fractal micro- and nanostructures formation caused by the electrical breakdown of the indium-tin oxide (ITO) covered with various organic coatings. The samples were created by covering a glass substrate with a 1 to 10um-thick layer of indium-tin oxide. Some of the samples were then coated with organic layers of polycarbonate, poly(methyl methacrylate) and others. In order to create high local electrical field densities a special setup based on a eutectic GaIn liquid needle was created: it allowed for the contact area of 60um in diameter and application of the step voltage swept from 20 to 300 volts. The setup also contained a spectrometer for measuring the spectra of the breakdown optical effects. The results showed that the destruction of ITO led to the formation of the spiral fractal nanostructures, parameters of which depended on the thickness of the layer and the presence of the organic cover. In case of the latter, polymer coating was shown to visualize and zoom the topography of the nanostructures which might be used as a method of "polymer photography" for such fractal formations. The analysis of the spectra showed their dependence on the parameters of the structures which proves the possibility of conducting optical diagnostics of the created structures.

The paper presents the possibility to build a tension gauge capable to discriminate different kinds of deformations: compression and twisting (induced by torsion strain) based on the magnetoelastic effect in new metallic glasses Fe_80−xCo_xP₁₄B₆. Applied loads increase coercive field H_c, saturation induction B_s and rectangularity of magnetic hysteresis loop. For example, hysteresis loop traced for 1 mm narrow, 50 cm long and 30 μm thick Fe₄₀Co₄₀P₁₄B₆ straight ribbon subjected to longitudinal stress of 346 MPa shown increased B_s from 1.24 to 1.7 T and squareness from 0.55 to 0.88 compared to unloaded specimen. For twisting, on the contrary, both squareness and coercive field vary whereas the value of B_s remains unchanged.

The design of the sensor materials with challenging gas-sensitivity can be solved by materials selection and their compatibility with the manufacturing technologies that allows to operate the process of formation of nanocomposite structure and to receive the required material. The polyacrylonitrile (PAN) as the conducting polymer with a highly π-conjugated polymeric chain due to flexibility for tailoring the structure of the final products by the pyrolysis method under the influence of incoherent IR-radiation is chosen. The aim of the work was to study the peculiarities of formation procedure of cobalt-containing PAN films. The gas-sensing Co-containing PAN films have been fabricated. The different temperature and time have been used to form the films. Depending on intensity and exposure time of IR-radiation the thermostructured PAN films with resistance values of · 10⁸ Ω to 10¹⁰ Ω have been fabricated. It is shown that the heat-treated PAN is the p-type semiconductor. Irrespective of the level of the modifying additive in film-forming solution and the time-temperature modes little change of film resistance has been found. It has been found that the Co-containing PAN films are gas-sensing films and have high selectivity to Cl₂ and NO₂. A stationary state gas distribution method was used for testing gas-sensing properties. Obtained the Co-containing PAN films are perspective for low-temperature applications as Cl₂ and NO₂ sensors.

This paper investigates a hydrophobicity/hydrophilicity of porous silicon by the contact angle method. Porous silicon series were obtained by electrochemical anodic etching of n-Si (100) and (111) under the current anodization density range of 5-120 mA/cm². For this purpose the original laboratory installation and the software «Measurement of contact angle» were developed. It is shown that, the contact angle can vary significantly (up to 80 degrees for (100)) depending on the current anodization Discussion of the results is carried out taking in account the composition of the functional groups and of surface morphology of the porous silicon. These results are important for developing porous silicon particles as nanocontainers in the targeted drug delivery.

Membranes of nanoporous aluminum oxide (alumina) have been obtained using the electrochemical etching technique by varying technological regimes. They were investigated by the Rutherford backscattering technique. The obtained spectra revealed distribution of elements over the entire thickness of the layer. It has been shown that almost all ions, which fly in the beam, fall into the channel - por Al₂O₃. This leads to a focusing of the charged particles beam.

Hybrid lead halide perovskite based optoelectronics is a promising area of modern technologies yielding excellent characteristics of light emitting diodes and lasers as well as high efficiencies of photovoltaic devices. However, the efficiency of perovskite based devices hold a potential of further improvement. Here we demonstrate high photoluminescence efficiency of perovskites thin films via deposition of resonant silicon nanoparticles on their surface. The deposited nanoparticles have a number of advances over their plasmonic counterparts, which were applied in previous studies. We show experimentally the increase of photoluminescence of perovskite film with the silicon nanoparticles by 150 % as compared to the film without the nanoparticles. The results are supported by numerical calculations. Our results pave the way to high throughput implementation of low loss resonant nanoparticles in order to create highly effective perovskite based optoelectronic devices.

We derive equations describing the electron tunneling ionization of the molecular orbitals without symmetry. The modified method of smooth matching the asymptotic wave functions with molecule's wave functions is suggested, to use the results of numerical calculations of the molecules in the GAUSSIAN. The spatial distribution of the current is considered for tunneling ionization the fullerene C₆₀. We obtained the ionization probability of individual orbitals and spatial distribution of the electron currents at different values of the field, a distance to the screen and orientation of the fullerene.

The process flow of unified integral multi-axis micromechanical gyroscopes and accelerometers fabrication by surface micromachining was developed. The process flow for typical n-type silicon wafer Si (100) contains over 20 primary operations, including 5 lithography steps using 5 masks with minimum features size of 1 pm. Special operations were discussed. Experimental results of sacrificial SiO₂ etching for poly-Si-on-SiO₂ structures using buffered solution of hydrofluoric acid and ammonium fluoride (1:4) were obtained. The undercut etching rate was approximately of about 20 nm/sec and the minimum time required for sacrificial SiO₂ removing under beams of 0.5-2.5 width was in in the range of 11 to 62.5 seconds. Finally two and three-axis micromechanical gyroscopes and accelerometers were fabricated.

We present the atomistic model and the simulation of a self-assembled growth of a silver nanoisland film and small groups of nanoislands on a glass substrate after thermal poling of the glass with a profiled electrode. The calculations were performed in molecular dynamics simulator LAMMPS taking into account the diffusion of the metal atoms towards and along the glass surface and their clustering. Lennard-Jones potential was used to describe metal-metal and metal-glass interaction. The potential parameters were determined to provide qualitative coincidence of the simulated configurations of the metal nanostructures and the experimental ones, such as an isolated nanoisland, a pair and a set of three nanoislands and a "plasmonic molecule".

This paper presents a method for online treatment of the distribution pattern of emission sites on the emitter surface, combined with a multichannel registration and processing system of the IVC. Using computerized field emission projector we have studied nanocomposite emitter based on carbon nanotubes "Taunit M" and polystyrene. The distribution pattern of emission sites over the brightness level was obtained as well as the emission area of the sample was determined. Time dependences of the current level, the total brightness and the emission area were registered.

Porous silicon nanopowders for target drug delivery were obtained by electrochemical anodic etching in a hydrofluoric acid solution using the monocrystalline silicon n-type conductivity. Porous silicon powders were obtained by sonification of porous silicon layers. The powders were functionalized by antibiotic Kanamycin and fluorophore Indocyanine Green by the passive adsorption method. The peculiarities of absorption spectra in 190-600 nm region were revealed for functionalized porous silicon powders dispersions in water.

The paper describes simulation of matrix field emission nanostructures on the basis of graphene on a semi-insulating silicon carbide. The planar spike-type field emission cathodes were measured. The electric field distribution in an interelectrode gap of the emission structure was obtained. The models take into account the distance between cathode tops. Screening effect condition was detected in planar field emission structure and a way of eliminating was proposed.

We considered the Coulomb explosion of single-component cylindrical nanoclusters. The analytical expression for the energy spectra of ions is obtained, as well as the spectral dependence on the cluster geometrical size is investigated. The laser ionization efficiency for cylindrical and spherical clusters is compared. It is shown that cylindrical targets are preferable in comparison with spherical ones, allowing obtain accelerated ions with higher energy at the same target radius.

Strongly interacting quark-gluon plasma (sQGP) was discovered in central heavy ion collisions at RHIC energies. Jet quenching is one of the sQGP evidence observed in particle yields suppression related to yields measured in elementary nucleon-nucleon collisions. System of Cu+Au collisions is characterized by special nuclear overlap geometry different to other large systems (such as Au+Au). Study of such collision systems will help to estimate sQGP properties with higher accuracy. Neutral mesons such as π⁰ give a good opportunity for studying sQGP effects especially jet quenching due to their large production rate. This paper presents results on neutral pion invariant differential spectra and nuclear modification factors measured with PHENIX experiment.

This article considers the reasons stimulating the research and development of a comparatively new method of analyzing the composition of liquids based on the spectral analysis of radiation of an electric discharge. Approaches to creating discharge cells for further analysis are described, including the scheme of the cell developed by the authors. To maintain the discharge has been developed a simple but rather effective electrical scheme with the use of a half-bridge driver. Emission spectra of the deionized and mains water shown in this work allow concluding that the sensitivity of the developed device is sufficient to detect even small concentrations of the substances dissolved in liquid.

Laser Doppler flowmetry (LDF) is a method widely used in diagnosis of microcirculation diseases. It is well known that information about frequency distribution of Doppler spectrum of the laser radiation scattered by moving red blood cells (RBC) usually disappears after signal processing procedure. Photocurrent's spectrum distribution contains valuable diagnostic information about velocity distribution of the RBC. In this research it is proposed to compute the indexes of microcirculation in the sub-ranges of the Doppler spectrum as well as investigate the frequency distribution of the computed indexes.

The paper discusses the features of the signal registration of nuclear magnetic resonance in a weak magnetic field from small volume of condensed medium. Method for determining the state of condensed medium in express mode, using measured by nuclear magnetic resonance relaxation time constants T1 and T2, is proposed. We have developed the new method of determining the composition of the investigated mixture and relative concentrations of its components. That method is applicable for mixtures that formed by condensed media similar in both physical structure and chemical composition.

We demonstrate numerically the possibility of multipole interference in the TiO₂ (titanium dioxide) microcylinders and microfrustums in the wavelength range 210-300 μm. Resonantly strong destructive interference between toroidal and electric dipole contributions to the scattered field is achieved by a geometry tuning. The toroidal and electric dipole mode overlapping at the resonant wavelength with almost total suppression of the total electric dipole moment is achieved.

We study radiation from hybrid Yagi-Uda nanoantennas composed of metal-dielectric core-shell nanoparticles. We show that due to the presence of two types of resonances in each particle at close frequencies the hybrid Yagi-Uda nanoantenna can operate in two different regimes. In the first regime at low frequencies it operates similarly to plasmonic and all-dielectric Yagi-Uda nanoantennas, and it is characterized with highly directive emission in a forward direction. In the second regime at higher frequencies the hybrid nanoantenna can emit with a high directivity in backward direction due to the presence of the hybrid dispersion branch with negative group velocity. Moreover by choosing the appropriate nanoantenna parameters one can achieve the operation regime when due to excitation of dark magnetic dipole modes in nanoantenna high values of directivity and Purcell factor are realized simultaneouslly in extremely narrow frequency range.

This paper presents the results of investigation Stark shift effect influence on the long-term stability of a dual scheme of quantum magnetometers. Such scheme allows suppressing Stark shift components when a certain pumping light polarization is applied. As a result, long-term stability of a quantum sensor increases. However, when low-frequency (LF) and microwave fields are attached to a single vapor cell a coherence circulation in hyperfine structure of alkali atoms takes place. Physical origin of this effect is associated with the so called "dressed" atom theory, when atom is "dressed" by LF field. It yields in multiphoton absorption and resonance frequency shift. First estimates for this shift based on density matrix evolution formalism are provided in the paper.

Nanocrystalline Eu³⁺-doped Mg2SiO4 powders were prepared with combined Pechini-solid phase synthesis. The structural properties were investigated with XRD, SEM and Raman spectroscopy. XRD pattern indicated that Mg₂SiO₄:Eu³⁺ were obtained with formation of other phase: MgO. Raman spectrum revealed good homogeneity and crystallinity of synthesized nanopowders. The luminescence properties were studied with measurement of excitation and emission spectra and decay curves. The effect of Eu³⁺ concentration on ⁵D₀ level lifetime was studied. Most probably, the observed shortening of ⁵D₀ level lifetime with Eu³⁺ concentration is caused by increase of nonradiative process probability.

The paper shows the possibility of assessing the functional state of microcirculatory-tissue systems of patients with diabetes mellitus by laser Doppler flowmetry (LDF), diffuse reflectance spectroscopy (DRS) and fluorescence spectroscopy (FS) methods. A review of the existing non-invasive optical technologies used to assess the state of microcirculation and oxygen metabolism in tissues of patients with diabetes is conducted. A series of experimental studies involving 76 patients with diabetes and 46 healthy volunteers was carried out. A wavelet analysis of LDF-grams was used to evaluate the adaptive changes of microcirculation during the temperature tests. The obtained data revealed that the proposed methodology in the form of combined use of several diagnostic technologies (LDF, FS and DRS) allows us to detect the presence or absence of trophic disorders and to evaluate adaptation processes during thermal tests.

We have investigated near field intensity distributions of InGaAs/GaAs/AlGaAs lasers possessing broadened waveguides based on coupled large optical cavity structures (CLOC) by scanning near-field optical microscopy (SNOM). The concept allows effective suppressing of the transverse high-order mode lasing. The obtained results can be considered to be the direct proof of pure transverse single-mode emission of the CLOC lasers.

A theory of plasmonic reflectance anisotropy spectroscopy (RAS) is developed for nanocluster layer at an interface. The model of identical ellipsoidal metal particles occupying the sites of rectangular lattice is used to calculate the effective plasmonic polarizability of nanoparticles. The anisotropic local field due to optically induced dipole plasmons and their interface-conditioned images is taken into account. Within the theory, resonant reflectance anisotropy spectra recently observed for In nanoclusters on InAs surface are explained, the anisotropy being associated with the difference between frequencies of plasmons with orthogonal in-layer polarizations. The frequency difference is treated in terms of anisotropy of the particles shape or/and the layer structure, its sign being opposite for the two types of anisotropy. The plasmonic RAS is concluded to serve as a method for investigating the anisotropy of nanocluster arrays.

Gold nanoparticles are widely used as a nano-sources of heat, but their properties are governed by skin depth which is usually less than 10 nm. In this work, we propose a mechanism for increasing efficiency of gold nanoparticles heat absorption in optical range. By 'wrapping' Au sphere in Si spherical layer we achieved significantly increased heating the nanoparticle in comparison with the gold filled sphere of the same size. The strong heating is caused by radiative losses suppression and more effective electric field concentration around the gold nanoparticle owing to adding of the Si layer.

Here we describe the efficiency of methods for obtaining optical wavefronts with the predetermined parameters, consider the main techniques of the wave field formation, and conduct the analysis of the applicability of these methods to specific problems. We also developed and analyzed the combination of wavefront formation methods. Among the results is the new method of the light beam synthesis based on the combination of the adaptive wavefront optimization approach and the direct prescription of the phase distribution via scalar diffraction theory.

We studied optical and second order nonlinear optical effects in arrays of frustum-shaped microstructures composed of orange-red dye by self-assembling technique.

Application of spectral devices for the detection of small concentrations of substances presents high demands on the signal dynamic range. Commonly used multielement photodetectors have a substantial nonuniformity of both sensitivity and dark signal that significantly narrows the dynamic range. For correction of such situation it was designed an amplifier with individual correction of gain and offset of a dark signal for each pixel that considerably enhances dynamic range and presents an ability to effectively detect weak signals.

Electroluminescence of InAs(Sb,P) heterostructures grown on InAs substrates was studied in the temperature range T = 4.2−300 K. At low temperatures (T = 4.2−50 K), stimulated emission was observed. This effect was due to optical resonator, which was formed between the lower face of the LED chip with the solid metal contact and the upper face with semiconductor/air interface. The emission became spontaneous at higher temperatures due to the effect of CHHS Auger recombination process, when the energy of a recombining electron-hole pair was transferred to another hole with the latter transitioning to the spin-orbit-splitted band. The results obtained show that structures based on InAs(Sb,P) are a promising material for fabrication of vertical-emitting mid-infrared lasers.

In this paper we present a study on temperature and current stability of far-field patterns of lasers based on the coupled large optical cavity (CLOC) concept. Previously it has been shown that the CLOC structures allows effective suppressing of high-order mode lasing in broadened waveguides. For the first time we report on transverse single-mode emission from the CLOC lasers with 4.8 μm thick waveguide. Using broadened waveguide allowed us to reduce the divergence of the far-field patterns down to 14° in continuous-wave (CW) regime. Far-field patterns proved to be insensitive to current and temperature changes.

Phosphor mixture based on colloidal quantum dots (CQDs) has been developed. Devices based on nitride LEDs and phosphor mixtures of CQDs have been created. CRI value of the devices exceeded 95.

In our investigation, we have modelled the quantum efficiency of the photodetecting structures based on the p-n junction and metal-semiconductor contacts. The calculation has been performed based on the solution of the continuity equation, taking into account the impact of the surface recombination. In most cases, this process has an adverse effect on the parameters of instruments; in particular, in photodetectors, this effect should reduce sensitivity. However, in our investigation it is shown that the effect of the surface recombination may be used as a useful factor for developing selective photodetectors. The effect of the surface recombination process will significantly increase with an increase of the absorption coefficient, since in this case more photons will be absorbed at the surface. Since there is a significant dependence of the absorption coefficient on the incident photon energy in semiconductors, the effect of the surface recombination on the photodetector sensitivity in the long-wave and short-wave regions of the spectral range will be significantly different.

Results of indium phosphide structures research, showing the possibility of using it in the near inferred range (NIR) photocathodes of InP / InGaAs, are represented. An optimal method of obtaining the atomically clean indium phosphide surface was suggested. The activation process of indium phosphide was shown and its spectral characteristics were given. Researches of the photoemission dependence of the structure with surface grid electrode upon different bias voltages were carried out.

The method of molecular beam epitaxy demonstrates the possibility to create high quality heterostructures of quantum cascade lasers in a spectral range of 7-8 μm containing 50 quantum cascades in an active region. Design based on the principle of two-phonon resonant scattering is used. X-ray diffraction and transmission electron microscopy experiments confirm high structural properties of the created heterostructures, e.g. the identity of the composition and thickness of epitaxial layers in all 50 cascades. Edge-emitting lasers based on the grown heterostructure demonstrate lasing with threshold current density of 2.8 kA/cm² at a temperature of 78 K.

We consider the advantages and disadvantages of various designs of waveguide for heterostructures of quantum cascade lasers (QCL) in a spectral region of 7.5 μm. Based on a numerical calculation we make a comparison of light wave distribution in QCL waveguides with different designs. We demonstrate the benefits of practical QCL realization with an extended five-layered waveguide formed by introducing extra layers of InGaAs, which allows to modify the spatial distribution of the light wave and get the rectangular shape of the spatial distribution of light wave intensity in the laser active area.

On the basis of the phenomenological theory of Landau was simulated electrocaloric response in ferroelectric. The obtained data were used for computer simulating of cooling of layered structure

This paper presents the technique of spectrum tuning in the multi-lamp solar simulator's workspace and accuracy (uncertainty) evaluation for measurement results of spectral irradiance in order to determine its suitability for GaInP/Ga(In)As/Ge multi-junction solar cells testing has been performed.

Domain walls in ferrimagnetic iron garnet films move under the influence of the applied static electric field and thus show the magnetoelectric behavior. We study theoretically two mechanisms proposed to describe this phenomenon. First one is based upon the inhomogeneous magnetoelectric interaction and the second one relies on the change of magnetic anisotropy parameters caused by electric field. We show that neither mechanism can be excluded by the general qualitative arguments.

A comparison of spectrum characteristics of ferrite and multiferroic magnonic crystals has been made for the first time. It is shown that ferrite-ferroelectric magnonic crystal band gaps shift in the low frequencies against ferrite magnonic crystal. Theoretical and experimental results are in good agreement.

We investigated two Rydberg atoms successively passing a vacuum or a thermal cavity taking into account the detuning. The atoms was assumed to be initially prepared in the Bell types entangled atomic states. Calculating the negativity we investigated the dynamics of atom-atom entanglement both for the vacuum and the thermal field. The special features of negativity behavior have been studied comprehensively foe small and large values of detunings. For thermal field and small detunings we established the effect of sudden death and birth of entanglement.

In a metal sample, where at least one of the dimensions is comparable with the de Broglie wavelength of conduction electrons, the quantum size effects (QSE) should be observed. QSEs manifest themselves as non-monotonic dependencies of various material properties as function of relevant dimension. QSE should be particularly noticeable in materials with charge carrier(s) effective mass less than the free electron mass. Bismuth is one of the most suitable semi-metal to observe QSE due to small effective masses and small the Fermi energy. However, bismuth has a high anisotropic energy spectrum. Hence to observe QSE which can be interpreted with reasonable accuracy, it is mandatory to fabricate single-crystal nanostructure with known orientation of crystallographic axes. In this paper several short bismuth nanowires (nanorods) were investigated, and oscillating dependence of electric resistance on effective cross section was found. Theoretical calculations provide a reasonable agreement with experiment. The quantum-size phenomena are important for operation of a wide spectrum of nanolelectronic devices.

The Kane's equations are written and solved with taking into account nonsphericity of the kp Hamiltonian. Charge carrier energy spectra and wave functions are obtained and analized. Subbands of dimensional quantization in the AlSb/InAs_0.84Sb_0.16/AlSb system are calculated with taking subband mixing into account. CHHS Auger process coefficient in the AlSb/InAs_0.84Sb_0.16/AlSb system is calculated with and without taking energy spectra nonsphericity and subband mixing into account. It is obtained that energy spectra nonsphericity and subband mixing lead to Auger matrix element and CHHS Auger process rate decrease.

We report an experimental study of the nonlinear response of single GaAs/AlGaAs quantum well. It was shown that bleaching effect manifested as reversible exciton spectral lines broadening can be suppressed by additional above-barrier illumination.

Plasmonic core/shell nanoparticles Ag/SiO₂ with different shell thicknesses were synthesized. Localized plasmon resonance was investigated by UV-vis spectroscopy. Arranged layers of plasmonic nanoparticles and quantum dots were obtained on a quartz substrate using a spin-coating technique. Plasmon-enhanced photoluminescence excited by 405 nm laser corresponding to the plasmon resonance was studied on CdS and PbS quantum dots structures. The possibilities of twofold and fourfold intensity increase are demonstrated for CdS and PbS quantum dots respectively.

In this work current-voltage characteristics of a glow discharge in neon and helium in long discharge tubes of various diameters at different pressures are investigated. Dependence of the longitudinal gradient of the plasma potential in the positive column of the pressure for different diameter of the discharge tube is found. Depending on the accommodation coefficient of electrons in various diameters, pressures and gas filling discharge gaps are obtained. The possibility of using described techniques for the calculation of parameters of the plasma glow discharge laser is shown.

Formation of the carbon films and coatings of different structural modifications can be efficiently achieved by sputtering graphite in a vacuum-arc plasma source. In this case the plasma flux is shaped in a form of a current-carrying jet with fairly distinct lateral borders. Spectral analysis shows that this plasma flux contains positively charged, excited and neutral carbon particles. In this paper is shown that for a technological cycle of deposition of a carbon-based coating it is possible to form a sublayer of the substrate material carbide, providing a possibility for the later growth of a well-formed coating.

An investigation of Improved Delayed Detached Eddy Simulation (IDDES) with Δy⁺-insensitive Near Wall Treatment (NWT) for prediction of turbulent heat transfer is performed in the framework of general-purpose CFD code ANSYS-Fluent for both fully attached and separated flows. The obtained results show that the considered approach is capable to predict the mean and RMS temperature with sufficient accuracy on the grids with the wall-adjacent step of about 1% of the velocity boundary layer thickness.

Beams of alkali atoms are typically used in precise quantum devices, such as atomic beam frequency standards. In order to know more exactly parameters of atomic beam tubes and frequency standards (frequency instability), it is necessary to investigate the propagation of Cs atoms after the channel exit. In this work theoretical calculations of angular distribution of Cs atomic flow from a microchannel are carried out. The Monte-Carlo direct numerical simulation of Cs atom propagation is also performed to estimate the influence of interatomic collisions on the atomic flow.

The most important unit of the plasma torch mainly subjected to the thermal load of the electric arc is electrode. Tungsten, hafnium, yttrium, aluminum, copper, iron and their alloys are used as electrode materials depending on the plasma-forming gas. Copper-based alloys can be rationally used for gases containing oxygen. The experiments were performed on the three-phase alternating current vortex plasma torch with power of 120 kW working on a mixture of steam, carbon dioxide, methane and carbon tetrachloride for the following flow rates 2.9 g/s, 2.9 g/s, 1.21 g/s and 2.44 g/s respectively. The material of erosion of copper rod electrodes was sampled from water-cooled walls of electric arc plasma torch channels made of stainless steel. The sample was divided into magnetized and non-magnetic parts. According to the energy-dispersive elemental analysis the products of electrode erosion contain oxides and chlorides of copper and iron, as well as metallic copper and iron.

The contribution deals with 2D laminar unsteady natural convection in a wedge-shaped reservoir model induced by the isothermal surface heating of a water basin being colder than surrounding atmosphere. The problem formulation considered corresponds to large-scale convection development during a cloudy day when the solar radiation impact is negligible. Numerical simulation was performed using an in-house Navier-Stokes code SINF. The focus of the paper is on the accurate resolution of the initial period of the convective circulation pattern development. The dependence of the predicted convective structures on the computational domain size as well as on the boundary condition at the free surface is analysed. The influence of geometry on the buoyancy-induced flow formation is discussed.

Supersonic MHD flow around a blunted body with a constant external magnetic field has been simulated for a number of geometries as well as a range of the flow parameters. Solvers based on Balbas-Tadmor MHD schemes and HLLC-Roe Godunov-type method have been developed within the OpenFOAM framework. The stability of the solution varies depending on the intensity of magnetic interaction The obtained solutions show the potential of MHD flow control and provide insights into for the development of the flow control system. The analysis of the results proves the applicability of numerical schemes, that are being used in the solvers. A number of ways to improve both the mathematical model of the process and the developed solvers are proposed.

A new automatic high-order hybrid central-difference/upwind scheme is developed for the finite-volume approximation of the inviscid fluxes within global hybrid RANS-LES approaches. Performance of the scheme is illustrated by examples of computations of three types of flow: a flow with massive separation with the use of Delayed Detached-Eddy Simulation (DDES), a flow with separation and reattachment with the use of DDES with shear-layer adapted subgrid length scale, and a fully attached flow with the use of Improved DDES (IDDES).

Hot Jupiters (HJ) are exoplanets, gas giants with low orbits (≤ 0.1 a.u.). The stellar X-ray and ultraviolet (XUV) radiation energy deposition result in heating ionization and the consequent expansion of planetary atmosphere. Expansion of upper atmosphere under certain conditions could be so large that the majority of light atmospheric constituents overcome the gravitational binding and escape from the planet in a form of hydrodynamic wind. Besides interaction of two counter-streaming plasma flows (stellar wind and ionized upper layers of planet atmosphere), each of this flows interact with planetary magnetic field. In such complex situation laboratory simulation can provide data that can't be obtained by computer simulation or observation. Experiment was carried out on KI-1 facility: high-vacuum chamber 5m long, 1.2 m in diameter with pressure ∼ 10^-6 Torr. Magnetic dipole with two attached laser targets played the role of a planet, and background plasma from θ-pinch used for simulation of stellar wind. As a result, data on a behavior of plasma density and magnetic field were obtained. The novel phenomenon was registered: magnetic field is transferred by the cloud of laser plasma, which was not observed before in experiments or calculations.

Four differential models for laminar-turbulent transition prediction were tested with different freestream turbulence levels on two cases: turbulent boundary layer and flow around NACA0021 airfoil. Computational results show that none of the considered models are able to predict transition in a wide range of freestream conditions. SA e^N model is applicable only for natural transition scenario with low freestream turbulence intensity and predicts fully turbulent solutions in other cases. Among γ-based models SST γ-Re_θ and SST γ have shown better agreement with experiment than SA γ.

Non-linear correction for the k-ω SST model based on the WJ-BSL-EARSM model was developed and tested for a wide range of flows. For the basic turbulence flows the corrected model (SST-NL) results are close to those of the linear SST model and surpass WJ-BSL-EARSM ones. At the same time non-linear correction is capable to predict secondary motion in rectangle channels and prevents false corner separation for flows around a wing-body junction as well as the WJ-BSL-EARSM model.

A mathematical model of the glaciation dynamics of the multilayer cylinder is suggested. The model reflects the specific feature of glaciation in salt water. The choice of effective model parameters and thermal characteristics of the increasing ice is considered. The calculations of problem using front-tracking finite difference method and using analytical solution found in quasi-stationary approximation are presented.

Temperature and the electric potential distributions in anisotropic thermoelements situated on substrates with different thermal properties are calculated. The influence of the geometric dimensions and thermophysical properties of the thermoelement and the substrate material to the electrical signal of the sensor is investigated. It is shown that at the initial stage of heating the influence of the thermal conductivity anisotropy of the thermoelement is negligible. On further heating the thermal properties of the substrate significantly affect to the temperature and potential distribution. Using a sensors with long thermoelements situated on the substrate with high thermal diffusivity can greatly simplify the processing of the measurement results.

New developments in the physics of plasma are presented, specifically, research of completely new method of atoms' and molecules' detection in gaseous phase – collisional electron spectroscopy. As a result, the microplasma sensor for quality and quantity analysis of the gaseous mixture was created. It works in the discharge afterglow mode using He as a buffer gas. In addition, the modification of the sensor using resonance photon photoionization was developed. This consideration gives the opportunity for wide practical appliance as an individual gas analyzer for industrial and medical purposes.

The eigen axisymmetric oscillations of a cylindrical gas bubble surrounded by an incompressible fluid with free deformable interface are considered. The bubble has an equilibrium cylindrical shape and is bounded axially by two parallel solid surfaces. Dynamics of contact lines is taken into account by an effective boundary condition: velocity of the contact line is assumed to be proportional to contact angle deviation from the equilibrium value. The equilibrium contact angle is right. Eigen frequency decreases with liquid outer free surface radius decreasing and increases with the radius-to-height ratio increasing. It's found that the eigen frequency can vanish in some wetting parameter interval for the volume mode of natural oscillations (which describes the radial compression of the bubble). The length of this interval increases with increasing ratio of the equilibrium bubble radius to the height. The eigen frequencies of other modes decrease with increasing Hocking's constant. The lowest natural frequency is observed for the freely sliding bubble.

The forced oscillations of incompressible fluid drop under the alternating electric field are considered. In equilibrium, the drop has the form of a rotational figure with arbitrary contact angle bounded axially parallel solid planes. The drop is surrounded by an incompressible fluid with another density. The external uniform electric field acts as an external force that causes motion of the contact line. In order to describe this contact line motion the modified Hocking boundary condition is applied: the velocity of the contact line is proportional to the deviation of the contact angle and the speed of the fast relaxation processes, which frequency is proportional to twice the frequency of the electric field. Using of this equation can qualitatively describe the experimental dependence of the contact angle vs voltage in contrast to the Young-Lippmann equation.

In this paper we studied the stationary states of plasma diode in the presence of a transverse magnetic field. We considered regimes without and with electron turnaround by the magnetic field. Stationary solutions depending on the electric field strength at the emitter for different values of the electrode gap, the applied voltage and the magnetic field were found. The stability of solutions was studied.

The paper deals with 2D laminar natural convection in vertical air-filled cavities of aspect ratio 20, 30 and 40 with differentially heated sidewalls. The airflow and heat transfer were simulated numerically with an in-house Navier-Stokes code SINF. The focus is on the appearance of stationary vortex structures, "cat's eyes", and their transition to unsteady regime in the Rayleigh number range from 4.8×10³ to 1.3×10⁴. The dependence of the predicted flow features and the local and integral heat transfer on the aspect ratio value is analysed.

It is proposed to use an organomineral additive based on glyoxal and saponite-containing waste in order to stabilize the road base. Preliminary studies have shown that soil modification with the organomineral additive with a quantitative ratio of components of glyoxal − 0.52 % and saponite-containing material − 17 % of sand mass increases its specific cohesion by 50 times. However, it is necessary to study the mechanism of interaction between the additive components and soil to optimize the composition and technology of additive introduction into the soil. This paper examines dispersion interaction in glyoxal/silica organomineral system. The Hamaker constant was chosen as a main parameter to evaluate dispersion interaction. This constant is determined based on the principle of measuring the contact angle of wetting with service fluids and calculating the dispersion component of material surface tension. The Hamaker constant in the glyoxal/silica organomineral system was 0.25·10⁻²⁰ – 2.8·10⁻²⁰ J at different glyoxal contents, while its maximum value was observed at 0.52 % glyoxal content. The results compared with literature and previously obtained data demonstrated good reproducibility.

The sorption mechanism of the mineral additive showed that self-saturation of the saponite-containing material with water vapors has a long-term nature (12 days). The nature of desorption differs from adsorption isotherm, i.e. the adsorption/desorption hysteresis is observed. Saponite-containing material samples studied after moisture desorption using infrared spectroscopy demonstrated that chemical compounds in the material have the ability to form calcium silicate hydrates when saturated with water. This fact along with the additive capability to control the water-cement ratio during concrete curing contributes to significantly better physical and chemical properties (strength, frost resistance) of the concrete composite.