The article considers the issue of measuring and controlling the parameters of a high-voltage AC circuit using a Bragg grid. A model of a fiber-optic sensor based on the magnetostriction effect, the main component of which is a fiber-Bragg grating, is proposed. The 3D modeling of the magnetostriction process and the design of the block diagram are carried out.
Keywords: optical fiber, magnetostriction, bragg grid, AC, sensor, solenoid, coil, nickel, ferrite, MathCAD, COMSOL
Experimental studies on the formation of nanoscale structures on the surface of gallium arsenide were carried out. To obtain a modified layer on the substrate surface, the method of focused ion beams was used, and the method of plasma-chemical etching was used for the subsequent formation of structures. According to the research results, structures with a width of 90 to 196 nm and a depth of 2 to 9.6 nm were formed. The results of the studies can be applied as structures for the subsequent formation of quantum dots during molecular beam epitaxy.
Keywords: Nanotechnology, focused ion beam, plasma treatment, atomic force microscope, GaAs
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
In the article, a numerical study of the heat sink with a change in the aggregate state of the oil is carried out. Simulation was carried out in Ansys Fluent CAD for two modes, static - with constant heating of the oil at 340K and dynamic, at which the heating temperature varied with time from 340K to 270K. Heat transfer in the event of a change in the aggregate state of a substance is widely used in cases where it is necessary to achieve the maximum efficiency of heat exchange. In this case, the energy is expended on the phase transition of the substance, for example, to evaporation from the liquid phase. The advantage of the heat-sink design described in this work is a rather high rate of heat transfer, greater resistance to various influences, including mechanical ones, which is primarily ensured by the simplicity of construction, eliminating the drawbacks of classical designs, which are cumbersome (the presence of an external cooling circuit ) and the limited rate of heat transfer.
Keywords: heat dissipation, numerical methods, aggregate state, computational experiment, heat exchange efficiency
In the article, the authors carried out a computer experiment in Ansys Fluent CAD to study the efficiency of a heat sink surface in terms of reducing the temperature of a heat-loaded source. Providing optimal thermal conditions for electronic products is one of the most important problems in the design of radio electronic equipment. Increasing the temperature of electronic products significantly reduces the reliability of their work. The work is devoted to numerical modeling of the heat sink surface efficiency of a pin radiator with an internal heat source. A conclusion is drawn about the ineffectiveness of performing a heat sink pin surface, not the entire surface is equally effective.
Keywords: thermal mode of equipment, pin heat sink, numerical methods, aerodynamic flow
The simulation algorithm for the system of microwave electronic devices with the method of nonautonomous blocks is given in this article . The voltage-current characteristic of the wave nonlinear element, which is the basic element in the theory of the electronic wave chain, is calculated.
Keywords: microwave electronic device, electric circuit, wave non-linear element, four-terminal network, the current-voltage characteristic, method of nonautonomous blocks
Numerical physical-topological modeling is carried out to optimize the thickness of perovskite solar cells on the basis of the heterostructure TiO2 / CH3CN3PbI3-xClx / Spiro-OMeTAD. The results of the conducted studies showed that the optimum values of the thicknesses of TiO2 and CH3CN3PbI3-xClx heterostructure films, which make it possible to obtain a high coefficient of efficiency of the solar cell, lie in relatively narrow limits. The carried out researches have shown the possibility of effective use of numerical physical-topological modeling for the development of perovskite solar cells, taking into account the features of photogeneration, recombination and transport of charge carriers in real heterostructures.
Keywords: Solar cell, perovskite, titanium dioxide, heterostructure, numerical simulation.
In this work, a study was made of the efficiency of the heat sink surface of a volumetric body with an internal heat source. An electrostatic analog of the distribution of the thermal field is chosen. A model of the convective flow is proposed, under certain initial and boundary conditions, the thermal conductivity of the medium transforming into heat removal. The conclusion is made about the ineffectiveness of the heat-conducting surface in the form of whip, finned and other designs of existing heat sinks, increasing only the mass, technological complexity of manufacture, thermal resistance and temperature of the heat-loaded element.
Keywords: Temperature field, convective heat transfer, effective heat sink area, electrostatic analog, similarity theory
Theoretical studies of the temperature distribution during laser heating of the TiO2 precursor film on the FTO/glass substrate have been 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 TiO2. It was shown that on the surface of the TiO2 precursor the temperature reaches a maximum value at a time point of 133 ns with the Gaussian temporal form of the laser pulse. The optimum energy density for crystallization of the TiO2 precursor film with the nanosecond pulse duration is 1.3-1.6 J/cm2, when the film thickness temperature corresponds to 400-500 °C. The obtained results of the simulation are consistent with experimental studies.
Keywords: numerical simulation, laser heating, temperature distribution, TiO2 film, solar cell
In this paper, the temperature distribution from a point source of heat under convective heat transfer is studied. The Navier-Stokes equation describing the steady two-dimensional laminar motion of a fluid is solved numerically. The distribution of the temperature field of a heat-loaded point source is obtained under appropriate boundary conditions, supplemented by the boundary conditions for the flow velocity to equal zero on the paraboloid walls by numerical integration using the control volume method.
Keywords: Radiator protrusion shape, thermal conductivity, thermal apparatus mode, the temperature of the heat source
TiO2 thin films are widely used as a transparent layer n-type conductivity in the perovskite solar cells. Nanocrystalline TiO2 films were deposited on the surface of glass substrates coated with tin oxide with fluorine (FTO) by spin-coating and subsequent laser annealing radiation with a wavelength of 1064 nm. The effect of laser annealing on grain size in the TiO2 film and spin-coating speeds on its thickness. It is found that the grain diameter in the resulting TiO2 films on average 17-64 nm at a power of laser annealing 30-70 W. It was found that the thickness of the TiO2 film is changed in the range of 72-124 nm spin-coating speed. Optimal parameters TiO2 thin film formed by laser annealing can enhance the efficiency of the perovskite solar cell.
Keywords: thin film, TiO2, centrifugation, laser annealing, surface morphology, thickness
The influence of the laser material on the structure of the photocell based on thin films of zinc oxide and amorphous silicon on glass. It was modeled recrystallization processes in the solid state, considered the interaction of the surface of silicon by pulsed laser radiation, calculations are made for the surface temperature at the recrystallization of the amorphous film on Nd:YAG laser installation with length wave 532 nm. The proposed thermal model of the solution of the problem showed that the structure melt is already at the earliest stage of processing and the temperature distribution in the amorphous layer will depend on the structure of the ZnO film, as evidenced by modeling in ANSYS. According to the results of experimental studies performed, it can be said that the thermal conditions at the plant are poorly worked out, as evidenced by the roughness of the film of the amorphous layer. The mechanism of crystallization of the melt also requires refinement. The obtained results showed the prospects of the direction of silicon-on glass and ZnO
Keywords: solar cells , laser recrystallization , an amorphous layer , ZnO film , thermal model , modeling of thermal modes , tube scan
Nanocrystalline TiO2 films are used as transparent layer n-type conductivity in the perovskite solar cells. The work presents the numerical diffusion-drift modeling of the transport processes and the accumulation of charge carriers in the heterostructure of TiO2 / perovskite / p-type semiconductor. The basis of the simulation put stationary physical and topological model based on drift-diffusion equations and semiconductor system allowing to model perovskite solar cells with a variety of electro-technological and constructive parameters. Obtained photovoltaic solar cell characteristics and plotted the efficiency of the TiO2 film thickness. The optimal thickness of the TiO2 film is 50-100 nm, thereby increasing the perovskite solar cell efficiency.
Keywords: Solar cell, thin film, titanium dioxide, p-i-n structure, numerical modeling
The results of an analytical study of diffraction of surface waves in anisotropic gradient open planar structures were presented in this work. The solutions of the wave equation and the possible values of the constants of propagation for waves in the complex plane transverse wave numbers were found. We obtained a graphical expression of the reflection coefficient of the first guided magnetic modes from the given size of the cross-structure for different values of the gradient parameters in the transverse profiles of the elements of the dielectric tensor of waveguide layer. We finally showed the possibility of practical applications of all results.
Keywords: compositional structure, waves of the discrete spectrum, the gradient tensor of the dielectric suseptibulity, the reflection coefficient of the first magnetic modes
The mathematical basics of the non-classical approach to the logical synthesis of k-valued digital structures, based on the replacement of the classic mathematical apparatus of logic synthesis (Boolean algebra) to the proposed mathematical apparatus - linear algebra are considered. The limiting properties of Boolean algebra, preventing further improve the technical ICs characteristics are discussed. One of the possible directions of overcoming these properties is the transition to a multi-valued logic. A new in a logical synthesis concept of linear synthesis of digital structures is proposed. A strong definition of linear algebra and its basic properties are shown. The logic synthesis process of two valued and multi-valued digital structures in linear algebra, including the formation of bases of a linear space, the original representation of the implemented logical function, obtaining decomposition of logic function according to the system of basis vectors are considered.
Keywords: multi-valued logic, Boolean algebra, linear algebra, linear logic synthesis, linear digital structures, bases of the linear space, decomposition of logic functions, logical variable, logical synthesis, digital logical elements
Results of research of abrasive treatment influence on process of defects formation in sapphire crystals are presented in article. On the basis of the received results recommendations about determination of properties of sapphire near-surface layers and about improvement of crystal quality are developed. Researches of influence of abrasive treatment on process of defects formation in sapphire crystals allow to choose the optimum modes of process of receiving sapphire monocrystals products.
Keywords: sapphire, abrasive treatment, defect, optimum mode, crack, near-surface layer, grinding, polishing
The author presents the method of calculation of temperature and thermoelastic fields during sapphire crystals growth by horizontal directed crystallization method. Realization of the offered technique allows to carry out the analysis of changes of the temperature and thermoelastic fields in the crystal taking into account spatial and geometrical characteristics of heaters by means of computing experiment. On the basis of the analysis we can carry out redistribution of defects in sapphire, and increasment quality of the grown crystals.
Keywords: sapphire, temperature fields, thermoelastic stresses, horizontal directed crystallization method, technique, computing experiment
Piezoceramics phases of (1-х)PbTiO3-xPbZrO3 is the basis of most high-performance piezoelectric materials. Electrophysical and mechanical properties of these materials can be varied over a wide range by varying the composition and by processing methods: the methods and modes of sintering conditions polarization. Topical to study the influence on the properties of PZT materials processing methods at the stages of manufacturing piezoelectric samples. In the role model of the object has been selected multicomponent system PbTiO3-PbZrO3-PbNb2/3Zn1/3O3-PbW1/2Mg1/2O3-PbSb2/3Mn1/3O3. Samples of piezoelectric elements for the study were obtained in two ways: in the first case, the sintering samples was carried out by the usual ceramic technology, and in the second by hot pressing. The grain structure was formed in both cases in the presence of the glass phase, the quantity of which decreases with increasing temperature, while in the first case, an increase in the velocity of the secondary recrystallization, and in the second of its suppression. It was found that regardless of the technology of the samples εT33/ε0, d33 and VЕ1 at high temperatures, due to the increase of grain and coercive field, which complicates the process of polarization. Maximum values εT33/ε0, d33 and VЕ1 samples prepared by hot pressing at 10 - 15% higher than if received by conventional ceramic technology.
Keywords: Piezoelectric ceramics, doping, combination, pezophase, piezomaterial
Pedestrian navigation systems with redundant number of inertial information sensors have a great potential in reliability, measurement accuracy and low level of noise. Therefore the aim of this article is to investigate the features of constructing the inertial measurement unit comprising the redundant number of the primary information sensors. To achieve this goal, the mathematical model of the measurement unit implemented as a square pyramid with combined sensors of the acceleration, angular velocity and magnetic field strength on its faces was first analyzed. Then, the data processing algorithm of the measurement module was discussed. Finally, the conclusion is made about the feasibility of using the considered redundant measurement unit as the sensing element of a miniature pedestrian navigation systems to provide improved navigation performance.
Keywords: accelerometer, gyroscope, redundancy, inertial navigation, inertial measurement module, aggregation, magnitometer, micromechanical sensor, wearable electronics, personal navigation
Created single-stage model of silicon solar cell using PC1D v.5.9 program, designed to simulate the photovoltaic devices. In the process of simulation change the level of doping and thickness of the n + type layer of the front, as well as applied texturing the front surface. The influence of the doping level and the thickness of the n + type layer in the photovoltaic solar cell characteristics. It was determined that with the increase of the doping level and the thickness of the front n + -layer a decrease in the efficiency of solar cells. It was found that the use of texturing the front surface leads to an increase in efficiency and is associated with reduced reflection losses and an increase in the photocurrent.
Keywords: Silicon solar cell thickness, doping levels, texturing, current-voltage characteristic
Currently, laser annealing are widely used to create a polycrystalline silicon film, which is promising for use in thin film solar cell, and transistors, liquid crystal displays and sensors due to recrystallization of amorphous and nanocrystalline silicon films. The study of morphology and surface conductivity of single-crystal silicon film on a glass substrate by laser annealing power. Laser annealing is carried Nd: YAG laser with a wavelength of 532 nm, speed of movement of the stage with a specimen of 5 mm/s and a laser power ranging from 34 to 86 watts. The laser beam was focused on the sample in the form of a narrow line width of 10 microns and 60 mm in length. The dependence of the size of the nanocrystals and the conductivity of silicon films on the power of the laser annealing radiation. It is shown that the power of the laser radiation in the range of 60 to 70 W is optimal for the best electrical parameters silicon film for the purpose of its use in high-performance thin-film solar cells.
Keywords: silicon film, laser annealing, surface morphology, electrical conductivity, thin film solar cell
The author describes the technological schemes of films formation on sapphire surface for gas-sensitive sensors with use of laser radiation with wavelength of 1064 nm. It is defined that laser radiation allows to increase productivity at gas-sensitive elements reception, to modify crystal and defective structure of materials, to increase quality of oxide film, reproducibility of film parameters and their stability.
Keywords: sapphire, film, gas-sensitive sensor, laser radiation sensitive element, technological scheme, semiconductor materials
The technological scheme of sapphire and glassy dielectric PbO – B2O3 – ZnO juncture formation is suggested. The centrifugation method was used for sapphire and glassy dielectric PbO – B2O3 – ZnO juncture formation. It allows to form uniform films with thickness of units to tens of microns. Researches of the received films surface morphology were made by method of atomic force microscopy.
Keywords: sapphire, glassy dielectric, technological process.
"One of the major drawbacks of modern alloyed metal cathodes Pd-Ba is the inhomogeneous distribution of the intermetallic Pd5Ba in the matrix Pd. This fact leads to an underestimation of life and technical performance of devices of microwave electronics on the basis of the cathodes. A substantial improvement in uniformity of cathode alloys Pd-Ba should lead the operation of mechanical activation of powder Pd, carried out prior to its compression process. The paper studied the effect of mechanical activation on the particle shape, particle size distribution and dispersion of powder Pd. It is shown that mechanical activation results in a substantial reduction in the average size and average particle size of Pd powder, as well as a substantial increase of the specific surface of the particles. The optimal regimes of mechanical activation of powder of Pd with a view to its use for metallosplavnyh cathodes."
Keywords: alloyed metal cathodes Pd-Ba, mechanical activation, dispersion, particle size distribution, average particle size, surface area, the emission properties
The paper proposes a modification of earlier mentioned method reduces the number of computing operations and improve the accuracy of estimating the phase shift, which is close to the limit set by the Cramer-Rao inequality. The article also presents the results of numerical modeling of systematic and random errors parametric estimation of the phase shift angle of the proposed method.
Keywords: phase shift quasi-harmonic signal, Cramer-Rao lower band, parametric method