High-current semiconductor polycrystalline thermistors of high power of coaxial type have a large mass and consequently, considerable heat capacity and heat resistance. Due to this, the thermophysical and electrophysical processes in them are different in the steady and transient regimes, which is especially important in regimes. which lasts a fraction or a unit of seconds. The main variants of operation of such thermistors in dynamic modes are considered and various characteristics are given.
Keywords: Thermistor, thermal and electrophysical characteristics, electric motors, electrophysical and thermal characteristics of semiconductor thermo-resistors of coaxial type
The physical and chemical properties of cobalt catalysts for Fischer-Tropsch synthesis have been studied. The effect of copper and iron oxides on the specific surface, pore volume and dimensions, and the degree of reduction of metallic cobalt on the surface of the Co-Al2O3 / SiO2 catalyst have been studied.
Keywords: Fischer-Tropsch synthesis, synthetic hydrocarbons, catalyst, cobalt, promoter, carrier, specific surface, porous structure, catalytic activity, reduction degree
The paper contains an analysis of the results of experiments on obtaining radiative structures based on gallium antimonide, formed by the method of thermal melt migration in a semiconductor matrix. The epitaxial process modes within the selected range were optimized for such parameters as the wavelength corresponding to the fundamental transition, a small lattice discrepancy, a small discrepancy in the coefficients of thermal expansion of the growing TP and the matrix. An original effect is described - an increase in the solubility of the Bi content in solid solutions, isoperiodic binary compounds A3B5 under conditions of a gradient temperature field. This effect allows a wide variation in the optical parameters of the element base of instruments based on solid solutions of GaSbBi / GaSb. The mechanisms of the generation of dislocations in a crystallized solid solution and the features of electrophysical and photoelectric parameters are analyzed. A structural solution of a light-emitting diode with strip geometry is proposed.
Keywords: solid solutions, recrystallization, gradient liquid-phase epitaxy, thermomigration, indium antimonide-bismuthide, melt thickness, temperature gradient, components, growth coordinate, epitaxial layers
In this paper, the modeling of phase equilibria in multicomponent systems of A3B5 compounds was carried out and the compositions of the liquid phase equilibrated with a given solid solution were calculated. A model of excess thermodynamic functions is used, which takes into account the formation of associates in the melt near the solidus temperatures. The developed algorithm allows solving a direct problem (in which the input parameters are the growth temperature of the layers and the composition of the solid phase corresponding to the expected instrument characteristics) and the inverse problem (the growth temperature and composition of the solid solution are sought for the given liquid phase). The limiting concentrations of the alloying components, arsenic and bismuth, are determined. The structural and electrophysical characteristics of multicomponent semiconductor A3B5 heterosystems are discussed, the solid solutions of which crystallize from the liquid phase in a gradient thermal field. The mechanism for introducing impurities into the lattice of epitaxial layers of multicomponent solid solutions is described for the first time. With an increase in the thickness of the crystallizable film, the thermodynamically equilibrium substitution by antimony bismuth atoms is completed and the introduction of Bi atoms into the interstices takes place. The interaction of neighboring atoms with the valence electron shells of Bi becomes more symmetrical, which causes an increase in concentration. The concentration of film defects near its rear surface also increases. The obtained values of electrophysical parameters make it possible to draw a conclusion about the instrumental suitability of the materials under study.
Keywords: solid solutions, mesostructure, antimonide, alloying, liquid phase, phase transformations, binary compounds, associates, lattice constant, multicomponent systems
Annotation: Several ways of utilizing the generated heat, produced by the final gas of boiler unit are analyzed in this article. The first method consists of implementing of heat pump into the process flow diagram of boiler-house plant. The second method encompasses the implementation of axifugal dry box into the process flow diagram. The dry box is implemented into the smoke removal system and also serves as axifugal smoke exhauster. The most widespread method is copious cooling of combustion product gas in steam condensing plants. The copious cooling of smokestack exhaust gases in steam condensing plants allows the full incorporation of sensible heat of smokestack exhaust gases (low heat value). The copious cooling allows the extraction of condensation heat of moistere vapours. The result would be the increasing ratio of utilization of boiler unit by 10-12 percent in optimum performance [ 5,6]. The implementation of steam condensing plant allows to decrease the concentration of nitrogen oxide in smokestack exhaust gases. The same effect can be achieved by implementation of heat pump plant. The efficiency of project implementation of steam condensing plant installation depends to a greater extent on the measure of the amount of hours of operation on peak capacity in recycling mode . Therefore, the way of optimization of boiler flow diagram with the implementation of steam condensing plant, is suggested. This article contains calculations and technical and economic assessment of implementation heat-exchange facility, installed on bypass pipe of opetational block-modulator boiler-house plant with capability of 0,2 Gcal/hr, located in Spassk .
Keywords: Boiler-house plant, Steam condensing plant, final gas, heating agent, heat supply system, heat recovery unit, process flow diagram of boiler-house plant, optimization, boiler unit, smokestack exhaust gases, heat producing plant, condensing, heat-exchange
A complex of technological operations for the formation of a cathode liner based on manganese dioxide is of particular importance in the production of tantalum oxide-semiconductor capacitors. Electrical characteristics and reliability indicators of capacitors are laid at this stage in their manufacture. In according with the classical technology, the formation of a semiconductor coating of MnO2 on tantalum capacitors is associated with multiple heating of oxidized anodes with the previous impregnation in solutions of manganese nitrate. It has a negative effect on the quality of the Ta2O5-dielectric. To minimize the defect formation in the dielectric, is realized a periodic electrochemical anodization of the tantalum anode in the acetic acid solution by anodic connection of the sections of the capacitors to the direct current source. The authors proposed to modify the process of reanodization of sections of tantalum oxide-semiconductor capacitors by changing the composition of the electrolyte. The results of the investigation of the electrochemical anodizing of a tantalum anode in aqueous solutions of nitric acid and manganese nitrate are presented, the morphology of the obtained coatings, their phase composition, as well as electrical parameters of the sections of capacitors manufactured by the proposed method are analyzed.
Keywords: Tantalum oxide-semiconductor capacitor, reanodization, manganese nitrate, capacitance, leakage current, dielectric loss tangent, electrolyte
The analysis of the influence of heating on the depth of polymerization of composite materials of light curing is carried out. An electronic micrometer was used to measure the polymerization depth. The greatest difference in the depth of polymerization before and after heating was obtained from Filtek ULTIMATE "3M ESPE" composite material. The smallest difference in the depth of polymerization before and after heating of Nexcomp "MetabioMEDCo". After heating, the plastic and flow properties of the materials are improved, which improves the adaptation to the walls of the cavity during the restoration.
Keywords: Light-cured composite materials, polymerization, heating of composites, micrometre
The problem of the propagation of nonlinear surface waves in a magnetized liquid of infinite depth is solved. The dependence of the frequency of wave oscillations on the magnitude of the magnetic field strength is shown in the graphs. Trajectories of motion of particles of liquid are found. The effect of a magnetic field on the height of a wave is investigated. The results of the study can be used to calculate various technical devices and technological processes.
Keywords: surface waves, magnetizable liquid, magnetic field, wave number, frequency of wave oscillation, magnetic field intensity
When modeling the transport of hot carriers in strong electric fields and using various mathematical relationships describing these processes, usually do not take into account inhomogeneities of impurity doping, which affect the field distribution and the density of the output current. In this paper, we calculated the field distribution along the length of the diode chip. In this case, a one-dimensional model and a phenomenological approach to the description of carrier behavior were used. The results obtained allow one to estimate the influence of the inhomogeneity on the operating modes of the Gunn diode and can be used to create models of higher orders.
Keywords: Gunn diode, numerical modeling, heterogeneity doping physical topological model
In the framework of simple volumetric models of electron concentration in the F layer of the polar ionosphere, the influence of non-stationary convection on the state of radio paths in high latitudes is considered. Calculations of three-dimensional trajectories of HF-radio beams showed a significant difference for quiet and disturbed conditions
Keywords: ionosphere, refraction, convection, plasma, radio beams, high latitudes
The paper presents the characteristics of wind and solar resources of the Southern Federal District on the basis of which the assessment of the prospects for introducing innovative innovations such as perovskite photovoltaic cells and Vertical-axis wind turbines into the process of district energy production is given.
Keywords: Vertical-axis wind turbines, alternative energy source, wind power, wind turbine, renewable energy source, perovskite photocell, solar battery, solar energy, energy resources of the Southern Federal District, energy saving
The article is devoted to the analysis of emergency situations related to the damage of gas-insulated switches on ultrahigh-voltage lines. The results of mathematical modeling of aperiodic oscillatory process produced in the Simulink system, which occurs when a high-voltage power line containing shunt reactors is switched on under the nominal voltage, are presented. The variants of using a switch with a set of pre-switched resistors in order to minimize the destructive influence of the aperiodic process that occurs when an overvoltage pulse occurs are considered. The results of the simulation of the switching process in the application of high-voltage switches with a set of pre-switched resistors. The simulation was performed on the parameters of the current transmission line with a nominal voltage of 500 kV on the site of the substation "Eletskaya" - nuclear power plant "Donskaya".
Keywords: shunt reactor, aperiodic process, high-voltage power lines
The dispersion parameters of the active component of cobalt catalysts promoted by nickel for Fischer-Tropsch synthesis by the temperature-programmed hydrogen desorption method (TPD H2) were studied. The influence of the polymorph (γ, θ, α) of the support on the physicochemical properties of the Co-Ni / Al2O3 catalyst was studied.
Keywords: Fischer-Tropsch synthesis, biomass, catalyst, support, Ni promoter, polymorphic Al2O3 modifications, TPD H2 method, active surface, dispersity, cobalt crystallites
Numerical modeling of the temperature distribution during heating (annealing) by a pulsed Nd: YAG laser of an amorphous silicon (a-Si) film on the surface of an AZO glass substrate is carried out. The simulation was performed on the basis of a numerical solution of the heat equation in the Matlab program to determine the energy density of the laser radiation necessary for crystallization of the a-Si film. For a wavelength of 1064 nm, it was obtained that the temperature at the surface of the a-Si film reaches a maximum value at a time point of 146 ns with a laser pulse with a Gaussian time-shape. It is shown that for the crystallization of an a-Si film with a thickness of about 800 nm with laser radiation with a nanosecond pulse duration, the optimum energy density is 600-700 mJ / cm2 when the temperature across the thickness of the a-Si film corresponds to 550-1250 ° C.
Keywords: Numerical simulation, laser annealing, temperature distribution, a-Si film, solar cell
This work relates to the technology of inorganic substances. It can be used in the production of aluminum-silicon and iron-silicon flocculants-coagulants. With their help, methods for treating wastewater from industrial enterprises, as well as storm water containing oil products. In this paper, concrete examples of the research results on the purification of natural, industrial and oily wastewater. With the use of new nanocomposite silica-alumina and iron-silicon flocculants-coagulants ASFC and ISFC, obtained by the new technology. The authors have developed and patented the technology of obtaining flocculants-coagulants of this type in solid form. Method of matrix isolation of active components has been used to prepare such composite materials. Performance evaluation was given to the action of coagulants, flocculants and ASFC ISFC. A comparison was made with the new composite materials commonly used for these purposes the conventional art, coagulants - aluminum sulphate and iron sulphate. With their help, the methods of treating wastewater from industrial enterprises, as well as storm water containing oil products. An assessment was made of the effectiveness of the action of coagulant flocculants ASFC and ISFC on real industrial wastewater.
Keywords: reagent purification of water, Natural water, Wastewater, Flocculants-coagulants, Matrix isolation, Nanocomposites; ASFC, ISFC
The scheme of calculation of nonstationary temperatures in the bodies heated by the radiation which based on the established dependencies between them is presented in the article. To study the process of radiation heating of bodies, the method of linearization functions proposed by one of the authors is used. The idea of the method is as follows. The linearizing transformation leads nonlinear boundary conditions to linear boundary conditions of the third kind. The solution of the linear problem in the stage of regular temperature regime is found by multiplying the corresponding solutions of one-dimensional transfer problems. After the transformations, equations are obtained that allow calculating the temperature fields in multidimensional bodies, if the temperature distribution along the coordinate axes or on the surface is known. There is no need to know the physical parameters of the material and the degree of blackness of the body surface.
Keywords: temperature field, radiation heating, multidimensional bodies, linearizing transformation, linear boundary conditions of the third kind
The paper presents the results of studies of the process of hydrated alumina homogeneous precipitation. The variants of this process are considered. As the most convenient embodiment of this process, precipitation of hydrated alumina from its salts using auxiliary substances. As such auxiliary substances, it is proposed to use urea. Urea hydrolysis proceeds slowly even with heating, which allows a homogeneous precipitation process under the most mild conditions. It is shown that the process of hydrolytic precipitation in the aluminum salt-urea system proceeds according to the dissociative mechanism SN1. For SN1, a two-step mechanism is characteristic, in which the first step is slow monomolecular hydrolytic dissociation, followed by a rapid coordination reaction with the second reagent. To determine the nature of the interaction of the aluminum salt with alkaline agents, experiments were conducted on potentiometric titration of the aluminum salt with solutions of ammonia and sodium hydroxide in the presence of various amounts of ammonium chloride and urea. When titrating with sodium hydroxide solution, the process proceeds to the formation of sodium aluminate, titration with a solution of ammonia produces a precipitate of hydrated alumina. Addition of ammonium salts shifts the equilibrium of the hydrolysis reaction towards the formation of aluminum hydroxide. The presence of urea virtually does not affect the course of the deposition process. To determine the uniformity of the formed sediment, the laser radiation scattering method. For these purposes, a special installation has been created that allows the capillary to be scanned through a focused laser beam. The homogeneity of the hydrated alumina precipitate formed was shown. Studies have been carried out on the use of homogeneously precipitated aluminum hydroxide as a binder in lightweight fibrous refractory materials. The process of precipitation of aluminum hydroxide particles proceeds primarily on the filler fibers, covering them with a thin film. The resulting film acts as a gluing agent. After drying and calcination, the gel deposited by the thin film becomes a solid that binds the fibers into a single monolith. The resulting materials have a developed specific surface area and porosity.
Keywords: homogeneous precipitation, hydrated alumina, composite materials, urea
The paper discusses the flow induced by centrifugal forces in helium II on the outside of the rotating cylinder. The analysis was carried out in the framework of Landau's two-fluid theory, in the approximation of a plane incompressible fluid. A two-parameter family of solutions of the equations of motion is revealed, in which the centrifugal forces for the normal component are fully compensated by counter-current (normal and super-fluid components) flows. According to preliminary estimates, the most stable of them is the flow, in which the pressure forces in the superconducting part are also compensated, The results show that in the analysis of helium II rotations it is necessary to take into account countercurrent instabilities.
Keywords: helium II, rotating cylinder, two-fluid theory, counter-current flows, stability, centrifugal forces, pressure compensation
The technique of improving the quality of remote diagnostics of cars is proposed. This method makes it possible to learn real-time and real-time information about the status of the functional units of the car, thereby assessing its technical condition.
Keywords: remote diagnostics, car service, car
The urgency of estimating the content of nitrates in food products to ensure environmental safety at an individual level is discussed in the article. Data on the negative effect of increased nitrate content in plant foods on human health are given. The results of the study on the determination of the content of nitrates in food products using a household nitrate counter "Soek nuk-019-2" are discussed. This device makes a conclusion about the concentration of nitrates by comparing the reference electrical conductivity of different types of vegetables / fruits with the electrical conductivity of a particular controlled product. It is determined that exceeding the MPC is observed in potatoes and onions, which are sold through a network of stores that occupy leading positions in the prevalence in Taganrog. Excess of MAC in carrots is observed only in its central part (core). Based on the results obtained, practical recommendations are given to ensure the safety of food consumption.
Keywords: food safety, food, nitrate content, household nitrate
The paper describes the regression model of the change in the ice coverage of the White Sea, obtained on the basis of satellite data of NSIDC. Changes in the ice coverage of the White Sea are mathematically described by a polynomial of the 6th degree, the quality of which is characterized by a coefficient of determination of 0.78. On the basis of the obtained mathematical model, the terms and duration of the phases of the ice regime of the White Sea are established, and also the analysis of the rate of formation and destruction of ice formations is given.
Keywords: ice coverage, ice phenomena, regression model, White Sea, satellite data of NSIDC
The article describes the algorithm of recognition of schematic diagrams in the framework of structural design of complex technical objects. It is specified that at statement of a problem of development of the specialized vectorizer it is necessary to define: software subsystems of the simplest tracer; algorithms of the analysis of images; formats of representation of the end result; initial data (formats) for recognition. As a result, it was concluded that for structural and circuit design, during which the vertex of the final portrait of the graph of the projected system is replaced, obtained after optimization by the criterion of the set of the smallest external stability, it is necessary to recognize images of graphic elements. The proposed algorithm allows for adequate recognition of the elements of electronic circuits, which further makes it possible to automatically replenish the database of elements with new elements in a given format.
Keywords: vectorization, concept recognition algorithm, structural design, graphic, element, raster image, electronic circuits, semi-graphical display, block-the functional distribution of the tracer
The comparison of different methods of selection of signs for identification of objects on digital images of microscopic preparations of sputum, colored by the method of tsilya-Nilsen. The following methods were considered: the method of intersections, Shannon, kulbaka and accumulated frequencies. It is concluded that the method of intersections allows the selection of features from the entire feature space so that the classification models allow to obtain the maximum accuracy of classification with the least number of input parameters.
Keywords: method Ziehl-Nielsen, object recognition, image recognition, selection of features, the method of cumulative frequencies, the method of Shannon, Kullback, the method of intersections, logistic regression, classification tree, discriminant analysis