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  • Physical and mathematical sciences. Physics

  • Methods of synthesis, properties and application of silica-zols for obtaining composite materials Part I

    The article considers examples of obtaining silica sols by ion-exchange methods. An analysis was made of the factors of this method that affect the properties of the resulting sols. The principal technological scheme of an industrial plant for the production of silica-sol by an ion-exchange method were considered. The results of studies of the sol-gel transition in silica-sol obtained by the ion exchange method were presented. The growth kinetics of colloidal silica-sol particles, which were obtained from solutions of polysilicic acid, was investigated. The dependence of the growth kinetics of colloidal particles from solutions of polysilicic acid on the temperature and on the initial pH of the sol was shown. The dependence of the gel time on the dimensions of the colloidal particles in the ash, on temperature, concentration and pH, was shown. The effect of the composition of the liquid phase on the stability of silica sols was established. Influence of the charcoal characteristics on the properties of the xerogels obtained. The effect of silica powder on the properties of the xerogels obtained was analyzed. An analysis of the possibilities of the practical application of silica powder as a binder in the preparation of heat-resistant heat-shielding composite materials was carried out.

    Keywords: silica-sol, ion exchange, sol-gel technology, stability of sols, xerogels, composite materials

  • Calculation of the efficiency of optical radiation input of DFB and VCSEL lasers into a glass integrated optical waveguide

    The efficiency of optical radiation input of semiconductor lasers of various types into an integrated optical ion-exchange buried waveguide in glass was calculated using optical circuits based on spherical, hemi-cylindrical and hemispherical lenses. Calculations were made by using the method of ray tracing. The single-mode waveguide, used in calculations, is the glass (type K-8) waveguide, made by ion exchange with subsequent burying. The results of the calculations indicate a low efficiency of optical radiation input when using single lenses. The use of a pair of microlenses (collimating and focusing) makes it possible to significantly increase the efficiency of optical coupling, which is 79% for a VCSEL laser. Efficiency of input is limited by a sufficient low aperture of the glass waveguide itself - 0.12. For more precise simulations the race tracing method with wave correction was used. The wavelength of optical radiation for calculations is 1.3 micrometer. The use of a single spherical and cylindrical lens has the advantage for it’s simplicity, but will lead to a serious loss of power in the optical system and, correspondingly, an increase of signal attenuation. This is partly due to reason that when using a single cylindrical or spherical lenses, according to the geometry of the calculations, the optical radiation will not be focused at one point, and essential aberrations take place. Efficiency of coupling with the help of two lenses is limited at first, by numerical apertures mismatch and, at second, partial energy transfer to the rings of Airy disk. The ion-exchange waveguide is suitable for coupling with VCSEL lasers for application in planar waveguide concentrators, etc.

    Keywords: integrated optics, optical waveguides, ion exchange in glass, VCSEL laser, ray tracing method, ZEMAX

  • Methods of synthesis, properties and application of silica-zols for obtaining composite materials Part I

    The article considers examples of obtaining silica sols by ion-exchange methods. An analysis was made of the factors of this method that affect the properties of the resulting sols. The principal technological scheme of an industrial plant for the production of silica-sol by an ion-exchange method were considered. The results of studies of the sol-gel transition in silica-sol obtained by the ion exchange method were presented. The growth kinetics of colloidal silica-sol particles, which were obtained from solutions of polysilicic acid, was investigated. The dependence of the growth kinetics of colloidal particles from solutions of polysilicic acid on the temperature and on the initial pH of the sol was shown. The dependence of the gel time on the dimensions of the colloidal particles in the ash, on temperature, concentration and pH, was shown. The effect of the composition of the liquid phase on the stability of silica sols was established. Influence of the charcoal characteristics on the properties of the xerogels obtained. The effect of silica powder on the properties of the xerogels obtained was analyzed. An analysis of the possibilities of the practical application of silica powder as a binder in the preparation of heat-resistant heat-shielding composite materials was carried out.

    Keywords: silica-sol, ion exchange, sol-gel technology, stability of sols, xerogels, composite materials

  • Influence of the method of introducing additives on the composition and porous structure of Co-catalysts for the synthesis of hydrocarbons

    Three batches of Co-MxOy / SiO2 catalysts were prepared with different methods of introducing an oxide additive. Physicochemical studies of catalysts by elemental analysis and Brunauer-Emmett-Taylor (BET) methods have been carried out. The effect of additives of oxide promoters and the method of their introduction on the specific surface, volume and pore sizes for Fischer-Tropsch synthesis catalysts were studied.

    Keywords: Fischer-Tropsch synthesis, carbon-containing resources, catalyst, active component, silicate carrier, Al2O3 and ZrO2 promoters, elemental analysis, BET method, surface area, volume and pore size

  • Influence of the method of introducing a promoter on the properties of the active component Co catalysts for the synthesis of hydrocarbons

    Using the methods of thermo-programmed reduction (TPV) and thermo-programmed hydrogen desorption (TPD H2), physico-chemical studies of Co-MxOy / SiO2 catalysts obtained by various methods of introducing a promoter additive were carried out. The effect of the introduction method and the nature of the promoting oxide additive on the properties of the active component of the Fischer-Tropsch synthesis catalysts was studied.

    Keywords: Fischer-Tropsch synthesis, catalyst, active component, silicate carrier, Al2O3 and ZrO2 promoters, TPV and TPD H2 methods, crystallite size, degree of reduction, dispersity

  • Methods for solving the problem of crystal-chemical design of composite coatings with anti-friction properties

    The interrelation of tribological properties of composite coatings with the properties, structure and distribution of surface phases, as well as the mechanism of formation of surface phases is discussed.

    Keywords: the structure of crystals, structural phase disorder, tribological properties of the surface phases of the composite coating

  • Physical and chemical properties of cobalt catalysts with promoting additives of copper and zirconium

    Physical and chemical properties of cobalt catalysts for Fischer-Tropsch synthesis are investigated. The influence of copper and zirconium oxides on the specific surface area, cobalt concentration, pore volume and size, the degree of reduction of the catalyst Co-Al2O3/SiO2 was studied.

    Keywords: Fischer-Tropsch synthesis, carbonaceous resources, catalyst, active component, silicate carrier, CuO and ZrO2 promoters, elemental analysis, recovery rate, BET method, specific surface area

  • Self-consistent model of the sol-gel process of film formation on substrates with homogeneous precipitation of particles of hydrated oxides

    This article analyzes the regularities of precipitation of solid colloidal particles of hydrated metal oxides on the surface of various substrates. Two models of this process are proposed. The proposed α-model is a process of continuous nucleation of interaction centers, at random points of a free surface throughout the process. The proposed β-model provides for the instantaneous nucleation of these centers when they are randomly distributed over the entire surface of the substrate. Based on the proposed models, the average values of the following values are calculated: the thickness of the gel film; its roughness and specific surface area. The calculations carried out in the article showed that these parameters are universal functions of the degree of filling of the surface and do not depend on the specific model of the mechanism of the process.

    Keywords: modeling, homogeneous precipitation, formation of thin films, sorbents, catalysts, heat-resistant composites

  • Research of influence of additives on physical and chemical properties of cobalt catalysts of Fischer-Tropsch synthesis

    The study of physical and chemical properties of cobalt catalysts in the synthesis of hydrocarbons by the Fischer-Tropsch method is carried out. The effect of additives promoters NiO, Fe2O3, MnO2, on the specific surface area, pore volume, size of cobalt crystallites, the degree of catalyst reduction is considered

    Keywords: Fischer-Tropsch synthesis, synthetic hydrocarbons, catalyst, promoter, carrier, specific surface area, porous structure, catalytic activity, dispersion, cobalt crystallites

  • Analysis of modern technologies for the use of vacuum and microwave effects in the dehydration of food products

    An analysis of the use of modern technologies based on the use of physical phenomena, namely, vacuum and microwave effects in the dehydration of food products, is given. On the basis of generalization and analysis of studies of domestic and foreign scientists it was shown that these technologies are promising for such plant raw materials as fruits and vegetables, and their effectiveness depends on the characteristics of the raw materials being enriched

    Keywords: vacuum, microwave exposure, dehydration of food, drying

  • Spatial equations of mechanics of composite solid for viscoelasticity models containing in one-dimensional case of two elastic and one viscous element

    For the first time, in the generalization to the spatial case of a one-dimensional viscoe-lasticity model for one viscous and two elastic elements, the stress deviators, deformations, and also the stress and strain rates were used. It is established that the model of a standard viscoelastic body (standard linear solid model) is more universal. The second model cannot be used to solve problems for a weighty body, or dynamic problems, since leads to the solution of an auxiliary physically unjustified boundary or initial-boundary value problem for doubled values of the accelerations. It means that the second model can be applied only to the solution of quasistatic problems for weightless bodies. It is established that the model of a standard viscoelastic body (standard linear solid model) is applicable only to the study of unsteady creep, while the second model is suitable for investigating the steady rheological behavior of a weightless material. Generalization of both models viscoelasticity for composite body was created. The effective Kravchuk-Tarasyuk values of the Poisson ratio, the Young's modulus, and the viscosity of composite material were defined.

    Keywords: deviator of stresses, deviator of strains, deviator of stress rates, deviator of strain rates, viscosity, standard linear solid model

  • Study of the bond strength of zinc electroplating with the surface of the machine parts from gray cast iron by planning a factorial experiment

    To ensure the stability of the galvanic deposition process and the high quality of the precipitate obtained, it is necessary to know the dependence of all processes on technological factors and modes. The degree of influence of technological factors on the behavior of machine parts made of gray iron, etching and deposition of zinc electroplating is not the same, so there is a need for electrochemical studies in the laboratory. The methodology of such studies has a General orientation and particular conditions in each case. The article describes in detail the method of electrochemical studies of gray cast iron in the sulfuric acid electrolyte of galvanizing during the restoration of machine parts by galvanic deposition of zinc coating. The basic conditions necessary for obtaining reliable comprehensive results that will determine the optimal conditions for galvanizing machine parts made of gray cast iron are considered.

    Keywords: technological factor, electrochemical studies, polarization curves, electrochemical cell, electrode, potentiostat

  • A new type of vortex-free flows of helium II in a rotating cylinder

    Within the framework of the two-fluid Landau theory, flows into helium II inside a rotating cylinder are investigated. Special attention is paid to the analysis of excitation by centrifugal forces of counter-current (by super-fluid and normal components) flows. In the approximation of incompressible fluid, an analytical solution of the equations of motion, vortex-free for both components is obtained. The tangential velocities for it are the same as those of a rotating solid body, with the normal and superfluid components moving in opposite directions, with different angular velocities. It's resulting vorticity is compensated by a spiraled counter-current radical movements. Such solution has no axial symmetry and has a tangential gap along the radius. Despite its instability, it is of some interest. First, it can be corrected by stabilizing deformations. In addition, it shows the paths of loss of stability of high-symmetric States. In particular, in our opinion, this type of disturbance are intermediate flow from Landau (superfluid component is at rest) one to the rotation of the Feynman type (in the superfluid part of a system of vortices).

    Keywords: helium II, rotating cylinder, two-fluid theory, counter-current flows, centrifugal forces, vorticity compensation

  • Determination of the yield stress of the material by static indentation

    For the first time, using the simplest model of an elasto-ideally-plastic coating, a relationship between the Meyer hardness and the absolute value of the yield stress of the material under compression was established for all types of indenters used for static hardness testing. The necessity for an accurate determination of the thickness of the layer in the simplest coating model is eliminated, when using the Prandtl bilinear diagram corresponding to an elasto-perfectly-plastic material as the equation of state. If the linear dimension of the test mark of the hardness is equal to 90 percent of the linear dimension of the total contact area, taking into account the elastic deformations, than the Meyer hardness is the absolute value of the compressive yield strength for the material under compression.

    Keywords: surface hardness, Meyer hardness, yield strength, ball indenter, conic indenter, pyramidal indentor

  • To the theory of electromagnetic waves in gradient structures with chiral meta-environment

    We investigated the process of propagation of the surface waves in the chiral meta-spectrum with gradient dielectric, magnetic and magnetoelectric permittivities in our work. We have found a condition for the existence of nonclassical plane electromagnetic waves in it. We have proved that the dispersion equation for the gradient chiral medium leads to four roots for the normalized wave vector. Thus, in this artificial environment, as in a homogeneous chiral medium, in general, four waves can propagate, differing in the direction of propagation. We took into account an anomalous propagation of waves in such an environment, when there can be more or less than two counter modes. So, we solved the most important mathematical problems of uncertainty or lack of solution (an unusual combination of signs of the transverse and longitudinal components of the wave vector) in our decision. Dependences of the component of the normalized propagation vector on the chirality parameter of the meta-environment and the components of the normalized wave vector on the parameters of the gradient of the spatial profiles of the material characteristics of the artificial medium were obtained.

    Keywords: gradient chiral meta-medium, compositional structure, plane electromagnetic waves, gradient tensors of material characteristics, normalized wave vector

  • Experience of using a moisture meter in studies of the kinetics of drying liquid lignosulfonate

    The article deals with the main problems of obtaining experimental data on drying liquid dispersed products. The main difficulties of using a moisture meter to obtain kinetic curves of drying difficult-to-dry liquid materials are given. On the example of lignosulfonate drying curves of samples of liquid product in different conditions are obtained. Presented that the application of the proposed method of the experiment on the moisture meter does not lead to early completion of the operation of the analysis of the drying process.

    Keywords: kinetics, moisture meter, drying, moisture, solvent, evaporation, lignosulfonates

  • Fractural analysis of pre-cracked simply supported beam

    the article considers behaviour of a simply supported pre-cracked beam made of elasto-plastic material. The aim of the work is to study propagation of min-span fractures in the beam, defining of its behaviour in the local area and developing of techniques and methods to prevent further growth of a crack. There were applied vary verify methods to analyse deflections, internal forces and stress intensity factor in the area of crack propagation. Analytical and numerical calculation had been used. For numerical solution ANSYS software is used, based on finite element method. According the solutions key features and conclusions are given.

    Keywords: fracture, pre-cracked beam, stress intensity factor, load-bearing capacity, elasto-plastic material, finite element method

  • Technical science. Instrument making, metrology and information and measuring devices and systems

  • Hierarchical classifier constructing problems for radio-photon sensor systems based on addressable fiber Bragg structures

    Radio-photon sensor systems represent a wide range of measurement information systems that use today's standardized parallel and sequential type optical analog chains with filtering, which allows to functionally display information received in the optical range in the radio frequency. One of the main, most widely used elements in the RPSS, which solves the problems of forming, filtering and measuring the conversion of optical radiation, including for the stage of further generation of radio-frequency carriers, is the fiber Bragg grating. The cumulative analysis made it possible to propose for the design of RFSSS a new class of sensors - address fiber Bragg structures (AFBS) constructed on the basis of FBG with two symmetrical discrete phase shifts or two identical FBGs potentially having improved metrological and technical and economic characteristics, as well as enhanced functionality compared with existing, widely used resonance sensors, based on the effects of Bragg and Fabry-Perot in fiber optics. AFBS, by its designation, should become a multifunctional element of the RPSS that act as sensors, formers of two-frequency optical radiation, the basis for generating in each of them a unique difference radio frequency carrying measurement information, which is also the address for their multiplexing. This made it possible to propose a new, separate class of the RPSS, which was named "Radiophotonic sensor systems on adressed fiber Bragg structures", the hierarchical classifier for the creation of which was the main subject of this article.

    Keywords: radio-photon sensor system, addressed fiber Bragg structure, integrated fiber-optic sensor, interrogation, multiplexing, hierarchical classifier of construction problems, system approach

  • Frequency-asymmetric two-band optical vector spectrum analyzer

    The article deals with the theoretical substantiation and computer modeling of an optical vector spectrum analyzer based on asymmetric optical two-band modulation using a parallel two-channel Maha-Zehnder modulator. The proposed method and device make it possible to achieve twice the measurement range in comparison with the classical optical vector analyzer based on single-band modulation and to realize a simpler and more reliable configuration in comparison with the previously presented amplitude asymmetric optical vector analyzer with two sidebands. It can be possible to measure the frequency characteristics of a fiber Bragg grating with a width of up to 0.5 nm (60 GHz) with a resolution of up to 1 MHz (about 5-10 fm) using electrooptical modulators with a bandwidth of up to 30 GHz.

    Keywords: optical spectrum analyzer, two-frequency modulation, frequency asymmetry, measurement range, fiber Bragg grating

  • Testing "sensor waterscout sm100" to monitor the soil moisture of the subgrade in the actual operating conditions of the road

    This article describes the approbation of the humidity sensor in the real operating conditions of the road. The authors have developed a protective design of humidity sensors that meets the requirements for their laying in the ground floor, developed a mobile portable data reader. The technology of calibration, calibration and laying of sensors in the soil of the roadbed is presented. The analysis of the data obtained after calibration of the sensors.

    Keywords: the soil subgrade, moisture monitoring in the conditions of the road, the humidity sensors

  • The method of rapid diagnosis of diesel engines of automotive equipment equipped with an electronic fuel system

    The article is devoted to the increasing role of new operational methods of Express diagnosis of diesel engines equipped with modern fuel equipment with electronic control, which allow non-destructive testing of technical condition. The method of rapid diagnosis of diesel engines of automotive equipment equipped with an electronic fuel system. Thus, the developed method of rapid diagnosis using a multi-cycle auto scan and diagnostic kit "Tester CR" allows to determine the technical condition of all elements of the power system "Common Rail" for any diesel engine, where such a system is provided, without dismantling the fuel pump and EGF.

    Keywords: Express diagnosis, technical diagnostics, fault, diesel, electronic control unit, fuel equipment, fuel pump, electro-hydraulic nozzle

  • Super resolution in digital holography

    The article considers a method of increasing the resolution of images in holographic systems based on subpixel shift algorithms. Methods of solving systems of equations of large dimension by reducing to block form are considered. The simplest solution is obtained when a set of matrices with an increased resolution is formed from a set of matrices with a shift in one direction, and then the resultant matrix is formed from the resulting set.

    Keywords: super resolution, subpixel shift, holography, solution of systems of equations, holographic interferometry, aperture

  • Techniques for technical diagnosis of cylinder-piston group of diesel engines with cold starting cranking of the crankshaft

    The main disadvantages of the methods of diagnosing the cylinder-piston group used at present are indicated in the article. Mathematical dependencies and the technique of technical diagnosing of a cylinder-piston group of diesel engines with a cold starting cranking of a cranked shaft developed on their basis are offered.

    Keywords: engine, cylinder-piston group, compression,diagnosis, cold idle cranking of the crankshaft