In this work, the basic relations of relativistic rocket dynamics in the case of a multicomponent jet jet are obtained and investigated. Various types of relativistic rockets with a single-component jet jet are considered as special cases of the general theory. The limiting transition to nonrelativistic rocket dynamics has been made.

Keywords: relativistic dynamics, multicomponent jet stream, ion engine, photon rocket

This study analyzes the microstructures of hot-deformed powder materials, considers the physics of processes, what physical changes the powder grains have undergone, which is monocrystallites of different sizes and configurations, the direction of crystallographic planes to the plane of the slot. The influence of the size of the initial particles on the structure formation of powder alloys, taking into account the features of homogenization during sintering, was investigated. The nature of deformation of particles of porous compacts from steel of two types of charge (coarse and fine iron powder, with different porosity) was considered.

Keywords: Physics of processes, fusion surfaces, quantitative characteristics, hot-deformed powder materials, microstructures, single crystallites, structure formation, particle size, homogenization

The global economy growth and active industrial development are limited, among other things, by the capabilities of existing technology. The potential for improving the functional characteristics of classical materials is practically exhausted, and the widespread use of new composite materials and high-enthalpy alloys is limited by the high cost and complexity of the technological process of their manufacture and processing. Knowledge of the materials physical-mechanical, thermophysical and chemical characteristics proves that the surface structural-phase state in many cases is crucial in the processes of wear, fracture, chemical and thermal destruction. Thus, the issue of developing technologies and equipment for modifying the surface layer and creating multicomponent coatings, including nanocomposite ones, is urgent. Current article presents the results of a study devoted to the creation of a facility for such coatings deposition by plasma spraying. One of the key elements of technological equipment for this method is a vacuum chamber, which is exposed to intense thermal stress during operation. Thus, the issue of designing a cooling system is relevant. To reduce the material and time resources at the design and experimental development, the temperature state of the chamber was simulated. It is shown that to ensure safe operation, it is advisable to use water cooling. The simulation results confirm the operability of the vacuum chamber cooling system under operating conditions. The following operating parameters were determined: the inlet pressure is 0.6 MPa, the water flow rate is 2 l/s, and the mass average temperature of the outlet water is about 40°C.

Keywords: plasma spraying, thermal state simulation, vacuum chamber, cooling system

The presence of vibration loads in any node or unit almost always leads to negative consequences in one way or another. Vibrations affect both biological objects and materials. High level of vibrations, under certain conditions can even lead to the destruction of the surfaces of parts and node as a whole. The purpose of these studies was to study the vibration-absorbing ability of zinc electroplating, used to restore the seating holes of the housing parts of machines. The main task was to determine the presence and the level of vibration-absorbing ability of zinc in relation to grey cast iron SCh18. The research was carried out on a laboratory prototype of a gearbox (gear reducer) with the use of vibration sensors and an oscilloscope. As a result, the vibration damping ability of galvanic zinc was proved and the comparative level of vibration damping in comparison with Cr18 cast iron was determined. For this study, zinc was electroplated from sulfuric acid electrolyte on the inner surface of the cast iron shells. First, readings were taken without zinc plating, then a 0.1 mm zinc layer was applied and readings were taken. After obtaining the data, the zinc layer was removed mechanically, the next 0.2 mm coating layer was applied and the readings were taken. The process was repeated with a coating interval of 0.1 mm until the zinc electroplating thickness of 0.6 mm was reached.

Keywords: load, vibration, vibration-absorbing capacity, electroplating, substrate, vibration velocity, vibration acceleration, oscillograms, sulfuric acid electrolyte, zinc coating, gray cast iron

Carbon formation in diesel engines affects an increase in the temperature of the sleeve, a decrease in the thickness of the oil film, an increase in oil fumes, which causes more intensive wear of the piston group cylinder parts. According to the theory of heat exchange, the heat flow from the working fluid (combustion products) is directed perpendicular to the surface of the piston bottom and is proportional to the equivalent temperature to the average heat transfer coefficient per cycle. Heat can also be supplied to the side surface of the piston bottom, but since the thermal gap between the piston head and the cylinder is small, the heat flow is insignificant. The deposition of carbon deposits on the bottom of the piston and cylinder head causes a slight decrease in its temperature, but at the same time the temperature of the cylinder liner increases, which causes a change in the gaps of the "piston-sleeve" interfaces. Experimental determination of interface gaps on a running engine is associated with significant difficulties. As a result, a computational and theoretical analysis of changes in the magnitude of thermal gaps was performed with a decrease in the thickness of the carbon layer on the bottom of the piston. The deposition of carbon deposits on the bottom of the piston indicates less favorable operating conditions of the piston-sleeve conjugations due to an increase in the dynamic performance of the cycle.

Keywords: quality, surface, part, performance properties, roughness, friction, wear, research, processing, physical and mechanical properties, hardening, deformation

A computer mathematical model was developed to predict the course of working processes in the device. To estimate the reliability of the obtained model, the study of mass-exchange characteristics of the experimental cooling device was carried out. Analyzing the graphs of mass-exchange characteristics of the model and the experimental cooling device it is possible to conclude about their correspondence. The conducted tests allowed to reveal three characteristic zones of distribution of two-phase gas-liquid flows arising in the working zone of the atomizer at the atomizer's output in the steady-state operation mode. It is proved that the optimum air pressure at the inlet of the vortex chamber can be considered as 0.10...0.15 MPa.

Keywords: ejection, cutting zone cooling, mathematical model, dispersant, emulsion, aerosol, lubrication, turbulence, pressure, mass transfer, atomization

In this work, the phonon format of graphane nanoribbons is calculated in the Hamiltonian formulaism. The geometric model is presented in the form of a graphene plane with hydrogen atoms attached to it. The unit cell of graphane contains two carbon atoms from solid graphene and two carbon atoms. The curvature of the graphene plane as a result of attachment to hydrogen atoms and hybridization of the outer electron orbitals of carbon atoms from sp2 to sp3, as well as the interaction between hydrogen atoms, are not taken into account. Analysis of the obtained phonon spectra shows that, for any type and width of graphane nanoribbons, there is a gap between acoustic and optical vibrational modes, in contrast to graphene, which can serve as an indicator for a given structure. Also, for the material under study, the values ​​of the speed of sound and the Debye temperature were calculated.

Keywords: graphene, graphane, nanoribbon, unit cell, vibrational spectrum, dispersion equation

The results of studies of the kinetics of the iron-catalytic oxidation of hydrogen sulfide by atmospheric oxygen in a reactor with a membrane separator are presented. The studies were carried out on a laboratory experimental complex. The dependences were obtained experimentally showing the effect of the catalyst dose - Fe (OH) 3¬, the pH of the medium, and the contact time of the water being purified with the reaction medium on the effect of water purification from hydrogen sulfide.

Keywords: hydrogen sulfide, iron catalytic oxidation, air oxygen, iron hydroxide, membrane separation, ultrafiltration

This article analyzes the existing methods of obtaining helium at the oil and gas condensate fields of the Russian Federation. The prospects of using membrane technology for obtaining helium from natural gas are considered, based on a comparative assessment of the use of various methods of helium extraction. Taking into account the different permeability of methane and helium, the possibility of using different types of membrane installations for the production of helium is shown. As membrane elements, the greatest effect is obtained from the use of artificial polymer fibers of cellulose acetate, as well as quartz glass. These membrane materials have chemical resistance, including to acid gases that are present in the composition of natural gas, as well as high resistance to temperature amplitudes.

Keywords: helium, membrane technology, natural gas, gas condensate field, cellulose acetate polymer fibers

One of the methods of thermodynamic stabilization of AN (ammonium nitrate) crystals, which is currently used not only as nitrogen fertilizer, but also as an environmentally friendly oxidant for gas-generating fuels for various purposes, is the technology of obtaining low-defect crystal structures. It is known that the potassium ion is a phase stabilizer of AN, and chlorine-containing compounds affect the rate of thermal decomposition of AN; therefore, there has been made an attempt to use a modifier, which includes both elements: potassium salt of monochloroacetic acid (PMCHAA) and to study its effect on phase transitions and thermal decomposition of AN depending on the amount of additive, type of solvent and crystallization temperature. As a result of the tests, it has been found out that a sample containing 1% PMCHAA (obtained at 80 ° C from an aqueous medium) most fully meets the requirements for EnCS oxidizers: the rate of thermal decomposition of the sample is 2.65 times higher than that of AN crystals recrystallized under the same conditions; the rate of modification transition IV – III has been reduced by almost 3 times

Keywords: ammonium nitrate, oxidizer, gas-generating compositions, polymorphic transition, thermal decomposition, additive, kinetics, thermodynamics, potassium salt of monochloroacetic acid, solvent, co-crystallization

The paper is devoted to cellular automaton modeling based on the class of cellular automata with the Margolus neighborhood. A simulation of the kinetics of gas emission in the final volume of coal, including: convection, diffusion, sorption, is performed. To organize this kind of evolutionary process, the cell-automaton modeling method was supplemented with the Monte Carlo method.

Keywords: cellular automaton, Margolus neighborhood, Monte Carlo method, diffusion, convection, sorption, porous medium, coal

In this work the data about the surface properties of melts on a base of Sn, Pb, Inare given. It is shown, that the best effect of wetting at brazing alloys Al- 4 аt.% Li is attained with the help of an eutecticum of system stannum - aluminium. It is shown, that at photon bakeout of films of stannum on siliciums within 3-4 seconds improvement of their wetting by melts on a base of stannum is provided. Perspectivity of use of composition solders on a base of copper and a nickel imbued by melts of stannum with small additives alkaline and alkaline-earth elements is marked.

Keywords: surface properties, brazing, ceramics, wetting, photon annealing, aluminum, surface tension

Method of hyperresonance desperation was applying for producing 4 types of organic nanopowders. We have discussed arias of application of such nano-powders.

Keywords: organic nano-powders, hyperresonance dispergator, application of organic nano-powders

The article describes the design of the integral micromechanical sensor of linear accelerations of the capacitive type; A construction method is briefly described using the self-assembly operation based on controlled self-organization of mechanically stressed semiconductor GaAs / InAs layers. The design of the capacitive accelerometer was modeled in the CAD system ANSYS, where static and modal analysis were performed. The results of mathematical modeling meet the requirements of modern micromechanical accelerometers, and allow them to be used for the further development of structures of this type. The obtained data can be used in particular for calculating the recommended parameters in the development of methods for designing capacitive sensors of angular velocities and linear accelerations and for developing more accurate models of MEMS structures.

Keywords: MEMS, microelectromechanical system, accelerometer, modeling, design, sensor, sensor, mathematical model

hydroxyapatite, non-collagenous protein, implant, quantum-chemical analysis, molecular model, one-electron spectrum, vibrational mode, osseointegration.

Keywords: hydroxyapatite, non-collagenous protein, implant, quantum-chemical analysis, molecular model, one-electron spectrum, vibrational mode, osseointegration

The work investigated the behavior of volumetric electrical conductivity (and its components) of various biological liquid media in order to determine the possibility of influencing the processes of life. In the frequency range 0-50 GHz, the following biological liquid media were studied: cold-pressed sunflower oil; sunflower oil obtained using heat treatment; fresh egg yolk and protein; Bacillus amyloliquifaciens bacteria; bacteria Escherichia coli MG1655 pXen-lux. The presence of fluctuations in the dielectric permittivity parameters, the unevenness of the frequency characteristics, in the range of 35-37 GHz, the “bursts” of values ​​characteristic of the resonance nature of this dependence were observed on the frequency characteristics of the loss angle tangents.

Keywords: biological liquid medium, dielectric constant, complex dielectric constant, loss tangent, medium conductivity, frequency response, fluctuation, frequency range, biophysical parameter

Various methods are used to scatter warm fogs: direct combustion of fuel in the fog; electric heating of the fog; introduction of streams or jets of warm and dry air into the fog; use of radiant energy for direct evaporation of hydrometeors; using explosions of highly heat-forming substances, etc. [4]. In this paper, artificially sprayed water droplets are used to scatter warm fogs. Refined calculations were made to investigate the possibility of fog scattering by artificial droplets. The model describes the fall of drops of radius r2 through the fog, consisting of drops of radius r1, the concentration of which is equal to n1. Detailed equations of gravitational coagulation are used taking into account the hydrodynamic interaction of droplets. The temporal characteristics of fog scattering (increase in visibility range) depending on the size of artificial droplets and their concentration are investigated. The size of artificial drops and their concentration, at which the maximum effect on fog scattering is achieved, are determined.

Keywords: scattering of warm fogs, meteorological visibility range, concentration of fog drops, fog water content, artificial influence on fog

The aim of this work is to estimate the density of the electron spectrum of objects with a dispersion bond, such as liquid helium, for example. The interest in its electronic properties is caused by the recently discovered dynamic polarization in the second sound wave, which made the study of its zone structure relevant. In this paper, the objects under study are modeled after born by a linear chain of coupled oscillators. The dispersion bond is considered on the basis of the quasi-classical London approximation, which takes into account the correlations of the oscillating dipole moments of atoms. The first part of the work is preparatory. A brief review of the new experimental data for helium II is given, and the problem statement is formulated. On simple examples (lines of two and three coupled oscillators) the research methodology is worked out. This section is of independent importance for rapid estimates of the density of the electron spectrum in dispersion coupling, and identifies trends in the change of spectrum parameters with an increase in the number of structural units. It is obtained, in particular, that the band width increases and the specific binding energy decreases slightly. In the second part, a long chain of coupled oscillators is investigated on the basis of the developed techniques. The density of the electron spectrum is calculated both for specific chains and in the thermodynamic limit. The results obtained in this work are planned to be used in the future for the development of dynamic polarization models for helium II

Keywords: dispersion forces, helium II, dipole moment, harmonic oscillator, coupled oscillations, normal mode, electron spectrum, density, narrow band, binding energy

The technologies for producing ultrafine copper powders are examined. The influence of various parameters on the processes of electrocrystallization of particles is studied. Various mechanisms for producing particles in the presence of water-soluble polymers are presented. The ultrafine copper powders obtained using different electrolysis modes. A review of advanced electrochemical methods for producing ultrafine copper powders with the addition of various stabilizers particle growth, further ways of developing the technology of these technologies are highlighted.

Keywords: ultrafine copper powders, electrocrystallization, production methods, particle stabilization, water-soluble polymers, double electric layer, vibrocathode

The article presents the results of experimental studies of the parameters of micro-sized metal particles and sprayed films obtained by the method of electric explosion of metallic conductors (EVP) and electro-explosive spraying (EVN), respectively. Copper (Cu) and aluminum (Al) metal wires were used as explosive conductors. Geometrical parameters and physicochemical analysis of the obtained microparticles and thin films were carried out by means of the universal two-beam electronic system Versa 3D. From the analysis of the obtained samples of sprayed thin films and fine particles, it follows that with a discharge current density J≈10 ^ 10 A / m ^ 2 millisecond, the film thickness and particle sizes can reach values ​​less than micron scale.

Keywords: electrical explosion of conductors, thin metal films, fine particles

The aim of this work is to estimate the density of the electron spectrum of objects with a dispersion bond, such as liquid helium, for example. The interest in its electronic properties is caused by the recently discovered dynamic polarization in the second sound wave, which made the study of its zone structure relevant. In this paper, the objects under study are modeled after born by a linear chain of coupled oscillators. The dispersion bond is considered on the basis of the quasi-classical London approximation, which takes into account the correlations of the oscillating dipole moments of atoms. The first part of the work is preparatory. A brief review of the new experimental data for helium II is given, and the problem statement is formulated. On simple examples (lines of two and three coupled oscillators) the research methodology is worked out. This section is of independent importance for rapid estimates of the density of the electron spectrum in dispersion coupling, and identifies trends in the change of spectrum parameters with an increase in the number of structural units. It is obtained, in particular, that the band width increases and the specific binding energy decreases slightly. In the second part, a long chain of coupled oscillators is investigated on the basis of the developed techniques. The density of the electron spectrum is calculated both for specific chains and in the thermodynamic limit. The results obtained in this work are planned to be used in the future for the development of dynamic polarization models for helium II

Keywords: dispersion forces, helium II, dipole moment, harmonic oscillator, coupled oscillations, normal mode, electron spectrum, density, narrow band, binding energy

Paper presents a review of scientific works investigating of effect of carbon nanotubes (CNT) concentration on electrical conductivity and pizeresistive properties of concrete. Different values of the percolation threshold for nanomodified concrete obtained by different authors are given. Recommendations for specifying the favorable concentration of nanotubes in composites are considered. As a result of review a need for additional dedicated research for the assessment of relation between favorable CNT concentration and their characteristics, method for the producing of composite and conditions of its application is stated.

Keywords: concrete, sensor, carbon nanotubes, percolation threshold, electrical conductivity, monitoring of stress-strain state

The article presents the results of experimental studies of the parameters of micro-sized metal particles and sprayed films obtained by the method of electric explosion of metallic conductors (EVP) and electro-explosive spraying (EVN), respectively. Copper (Cu) and aluminum (Al) metal wires were used as explosive conductors. Geometrical parameters and physicochemical analysis of the obtained microparticles and thin films were carried out by means of the universal two-beam electronic system Versa 3D. From the analysis of the obtained samples of sprayed thin films and fine particles, it follows that with a discharge current density J≈10 ^ 10 A / m ^ 2 millisecond, the film thickness and particle sizes can reach values ​​less than micron scale.

Keywords: electrical explosion of conductors, thin metal films, fine particles

First-principles simulation of ultrathin amorphous carbon films has been performed. Nanohybrid graphene-C60 systems were considered. Total energy calculations were performed using pseudopotential method within density functional theory. Local atomic structure and electronic energy spectrum of the systems were studied. It was demonstrated that fullerene-graphene interaction results in significant deformation of their local atomic structure. Obtained results are in good agreement with experimental X-ray UV spectra of hydrogenated amorphous carbon

Keywords: Phase-change resistive memory, ab-initio simulation, pseudopotential method, Kohn-Sham method, graphene, fullerenes, amorphous carbon, atomic structure, electronic structure, adsorption energy

The use of polymer concrete sleepers based on rubber concrete (RubCon®) with non-metallic composite reinforcement and the method of manufacturing such sleepers are described.

Keywords: sleepers, polymer concrete, rubber concrete, composites, reinforcement, manufacturing methods