Volume 88, №4
ACCOUNT OF THE NUMBER OF STAGES AND OF CYCLICITY IN THE PROBLEM ON ACIDIC STIMULATION OF AN OIL-BEARING STRATUM
The problem on the change in the porosity when hydrochloric acid is injected into a carbonate-containing stratum has been solved in a cylindrical coordinate system. Expressions for calculating space-time dependences of the porosity and the density of the acid in the solution during the stimulation of carbonate-containing oil- and gasbearing strata have been obtained. The derived expressions take account of the preceding changes in the porosity and the acid density in the previous stages of stimulation
Author: A. I. Filippov, I. F. Kabirov, and A. R. Karimov
Keywords: hydrochloric acid, density, porosity, reaction front
INFLUENCE OF THE TEMPERATURE OF GASES ON THE DEFORMATION CHARACTERISTICS OF MOVING WATER DROPLETS
An experimental analysis of the infl uence of the temperature of gases on the deformation characteristics of water droplets moving through them is carried out. High-speed (up to 105 frames per second) photography with video cameras and cross-correlation complexes, as well as panoramic optical methods of recording the motion parameters of gaseous and liquid flows, were used. The laws governing the movement of water droplets through gases with a temperature of about 1100 K and in air at relatively low (to 280 K) and moderate (about 300 K) temperatures have been studied. The principal characteristics of the deformation of water droplets (duration, extension, and amplitudes of "deformation cycles") have been established. The differences in the characteristic shapes of droplets during their motion in gaseous media (at different temperatures of the latter) have been determined. The times during which droplets retain a certain shape in the deformation process have been calculated
Author: D. V. Antonov, R. S. Volkov, A. O. Zhdanova, G. V. Kuznetsov, and P. A. Strizhak
Keywords: water; droplet; deformation; evaporation; gaseous medium; low, moderate, and high temperatures
DETERMINATION OF HEAT AND MASS TRANSFER EFFICIENCY ON A BUBBLING PLATE WITH ACCOUNT FOR SCALE TRANSITION
The effi ciency of heat and mass transfer in the bubbling bed on the plate has been investigated with the use of the method of combined physical and mathematical modeling based on the representation of the physical process in the form of a combination of elementary phenomena having a hierarchy of scales that permits realizing a scale transition in designing a contact device. The mathematical modeling of the heat and mass transfer in the above bed is based on the idea that the structure of this bed is invariant with its size and the interaction of the phases in it. A parametric investigation of the interaction of various effects in the process of heat and mass transfer in the bubbling bed on the plate and their conjugation has been carried out on the basis of the variational formulation of the conservation laws. Examples of calculating the effi ciencies of the heat and mass transfer processes on bubbling plates are given. The results of calculations were compared with the corresponding experimental data.
Author: A. G. Laptev and E. A. Lapteva
Keywords: bubbling plate, cellular model, variational method, scale transition, heat and mass transfer
INVESTIGATION OF THE RHEOLOGY OF FLUIDS IN FRACTURE AND PORE CHANNELS AND DETERMINATION OF THEIR OPENING
The authors propose a procedure to determine the parameters of a medium on the basis of generalization of results obtained in steady-state motion of viscous and anomalous fl uids in a plane-radial fracture. Also, the authors have developed a procedure to investigate the rheology of fluids and to determine the fracture opening and the equivalent permeability coeffi cient in a fracture system and have shown from these assessments the possibility of fluid inflow from a fractured-porous medium. It has been substantiated that the parameters of fracture and pore channels and rheophysical parameters of fl uids in these channels can only be determined on the basis of experimental investigations.
Author: M. A. Mamedova and R. S. Gurbanov
Keywords: fracture opening, permeability coeffi cient of a porous medium, fluid viscosity, direction of the flow
RESONANCE FREQUENCY OF BUBBLE PULSATIONS (APPROXIMATE SOLUTION)
The problem of bubble pulsations in a volume of a quiescent liquid with periodic external pressure fluctuations has been considered in a linear approximation. The incorrectness of the use of a polytropic approximation is shown. An approximate analytical solution for the resonance frequency of pulsations has been obtained
Author: Yu. B. Zudin, N. Sh. Isakov, and V. V. Zenin
Keywords: bubble pulsations, polytropic approximation, resonance frequency
ATOMIZATION OF NANOPOWDERS FOR ADSORPTION OF TOXIC SUBSTANCES
An experimental investigation of the dispersity and the specifi c surface of the particles of a pseudoboehmite nanopowder atomized by different methods for the purpose of formation of an aerosol has been carried out. It is shown that, as a result of the atomization of this power, the specifi c surface of its particles decreases and that this decrease is smaller in the case were the atomization is performed by the shock-wave method. The results of measurement of the dispersity of the particles of the pseudoboehmite powder in the process of its atomization and the further evolution of the aerosol cloud are presented. Photographs of aerosol particles have been obtained with the use of a scanning electron microscope
Author: O. B. Kudryashova, M. Yu. Stepkina, N. V. Korovina A. A. Antonnikova,a E. V. Muravlev, and A. A. Pavlenko
Keywords: aerosol particles, nanopowder, pseudoboehmite, nanopores, specifi c surface, volume-surface diameter
AIR EJECTION BY A FLUX OF PARTICLES OF A BULK MATERIAL IN A VERTICAL POROUS PIPE WITH A BYPASS CYLINDRICAL CHAMBER
Hydrodynamic equations have been derived for a flux of particles free falling in an air-fi lled circular porous pipe which is surrounded by a cylindrical bypass chamber. In these equations, the reverse infl uence of air on the particles′ dynamics is disregarded. Numerical and analytical investigations of the derived equations made it possible to establish the regularities of change in the velocity of ejected air in the porous chute and in the pressure in the bypass chamber along the chute length as a function of the porosity of the walls and the dimensions of the chamber, and also on the ejection number. A rational range has been determined for ejection parameters ensuring the greatest reduction in the ejection volume due to the recycling of air.
Author: O. A. Averkova, I. N. Logachev, and K. I. Logachev
Keywords: aspiration, bulk load transfers, air ejection.
INFLUENCE OF VOLUME DEFORMATION RATE ON THE INTENSITY OF OIL-BEARING CROP PRESSING-OUT IN RELATION TO RAPE EXTRUDATE
The infl uence of the volume deformation rate on the intensity of piston pressing-out of oil has been investigated. The results of pressing by a piston moving with different speeds are presented. Mathematical simulation is carried out for the stage of pressing-out after the termination of sample loading, when oil release occurs due to the accumulated deformations of the skeleton. It has been assumed that in mechanical pressing there remains the least residual content of oil. A dimensionless complex representing the ratio of the characteristic times of loading to the material response (the process of pressing) has been obtained. The dependence of the rate of oil pressing-out at the stage of pressure relaxation on the dimensionless complex has been determined.
Author: E. V. Slavnov and I. A. Petrov
Keywords: permeability, porous medium, volume deformation rate, fi ltration, pressing intensity, rape
MODELING OF THE FLOW DYNAMICS UPON CHARGE EXPLOSION NEAR A SURFACE
The dynamics of the processes proceeding upon explosion of condensed explosives in the air has been investigated. The paper discusses the physical model, the computing method, and the results of modeling a two-dimensional hydrodynamic fl ow initiated by the explosion of a spherical charge at some height above the ground surface. Explosions of charges at a height comparable to the size of the region occupied by the explosion products are considered. The results of calculations have made it possible to obtain a detailed space–time pattern of the initiated fl ow and investigate the incipient formation, propagation, interaction, and subsequent attenuation of shock waves. It has been shown that the distance to the surface can strongly infl uence the fl ow dynamics and parameters of shock waves.
Author: D. O. Morozov and A. S. Smetannikov
Keywords: shock wave, time, triple point, Mach leg.
MOTION OF A PARTICLE DURING NONLINEAR GAS OSCILLATIONS THROUGH AN OPEN PIPE IN AN UNSTRESSED-WAVE REGIME
The motion of a plane particle in a pipe and in an external field near the open end of the pipe in the case of forced longitudinal oscillations of a gas in an unstressed-wave regime is investigated experimentally. The time dependences of the particle coordinate for various amplitudes and frequencies of excitation are obtained. It is shown that near a piston the particle moves toward the open end of the pipe, whereas near the open end it moves toward the piston and executes longitudinal oscillations. Outside the pipe, the particle moves from the open end into the external wave fi eld virtually without oscillations. The position inside the pipe where the particle executes oscillations according to the harmonic law with no drift to any side along the axis has been determined.
Author: D. A. Gubaidullin, R. G. Zaripov, L. A. Tkachenko, and L. R. Shaidullin
Keywords: forced longitudinal oscillations, spherical particle, resonances, external wave field, experiment
SIMULATION OF SUPERSONIC FLOW IN A CHANNEL WITH A STEP ON NONSTRUCTURED MESHES WITH THE USE OF THE WENO SCHEME
A numerical simulation of flow in a channel with a right-angled step has been performed on nonstructured meshes having different resolving powers with the use of high-accuracy WENO schemes. The calculated shock-wave structure of this fl ow was compared with analogous structures described in the literature. Accuracy criteria of numerical calculations, associated with the position of shock-wave structures, are discussed. Recommendations on practical use of high-accuracy difference schemes for calculations on nonstructured meshes are given.
Author: P. V. Bulat and K. N. Volkov
Keywords: channel, step, supersonic fl ow, numerical simulation, WENO scheme
NUMERICAL SIMULATION OF THE CONVECTIVE HEAT EXCHANGE IN THE SEPARATION AIR AND OIL FLOWS IN A STAGGERED BANK OF ROUND TUBES IN A WIDE RANGE OF CHANGE IN THE REYNOLDS NUMBER
An analysis of the convective heat exchange in the separation air and oil fl ows in banks of heated round tubes and their hydraulic losses at Reynolds numbers changing in a wide range from 100 to 400 for the laminar fl ow and from 103 to 8·103 for the turbulent flow has been performed. For solving the Navier–Stokes and energy equations, multiblock computational technologies realized in the VP2/3 package and original procedures for correction of the pressure gradient in a fl ow and its mean-mass temperature were used. The Reynolds-averaged Navier–Stokes equations were closed using the Menter shear-stress transfer model modifi ed with account for the curvature of streamlines within the framework of the Leshtsiner–Rody approach with an Isaev–Kharchenko–Usachov constant equal to 0.2. The results of numerical simulation were compared with the corresponding experimental data of A. Zhukaukas. The dependence of the local and integral characteristics of a fl ow of a heat-transfer agent in a staggered bank of round tubes on the properties of this agent was determined.
Author: S. A. Isaev, Yu. V. Zhukova, and D. A. Malyshkin
Keywords: heat transfer, hydraulic losses, round-tube bank, air, transformer oil, pressure-correction procedure, multiblock computational technologies
SIMULATION OF THE TURBULENT AIR FLOW OVER A CIRCULAR CAVITY WITH A VARIABLE OPENING ANGLE IN AN U-SHAPED CHANNEL
A numerical investigation of the influence of the opening angle of a circular cavity in an U-shaped channel and the Reynolds number of a fluid flow in this channel on the local characteristics and turbulence of this flow has been performed based on the solution of the Reynolds equations, closed by the old and new Menter shear-stress transfer models and two variants of this model accounting for the curvature of streamlines, with the use of multiblock computational technologies realized in the VP2/3 package. The results of calculations were compared with each other and with experimental data of I. Castro and R. Savelsberg. This comparison has shown that the best agreement between the numerical predictions and experiments is obtained in the case where calculations are performed within the framework of the Leshtsiner–Rody–Isaev approach with correction for the eddy viscosity of the fluid flow. It was established that with increase in the Reynolds number and in the opening angle of the cavity the circulation fl ow in the near-wall layer of the vortex trapped in the cavity intensifi es at a practically constant vorticity in the core of the vortex.
Author: S. A. Isaev, P. A. Baranov, A. E. Usachov, Yu. V. Zhukova, A. A. Vysotskaya, and D. A. Malyshkin
Keywords: vortex cell, U-shaped channel, circular cavity, trapped vortex, turbulence
HEAT TRANSFER AND FLOW OF A CASSON FLUID DUETO A STRETCHING CYLINDER WITH THE SORET AND DUFOUR EFFECTS
Numerical solutions of the problem on flow and heat transfer of a non-Newtonian fluid outside a stretching permeable cylinder are obtained with regard to suction or blowing and the Soret and Dufour effects. The Casson fl uid model is used to characterize the non-Newtonian fluid behavior. The governing partial differential equations are reduced to a system of nonlinear ordinary differential equations by employing similarity transformations, and the obtained equations are solved numerically by using the shooting technique. The main purpose of the study is to investigate the effect of the governing parameters, namely, the Casson, Soret, and Dufour parameters, the suction/injection parameter, and the Prandtl and Reynolds numbers, on the velocity and temperature profi les, as well as on the skin friction coefficient and temperature gradient at the surface.
Author: A. Mahdy
Keywords: stretching cylinder, Casson fl uid, suction/injection, Soret and Dufour effects
ANALYSIS OF THE CHARACTERISTICS OF THE RETARDATION AND ENTRAINMENT OF DROPLETS IN A POLYDISPERSE WATER FLOW BY HIGH-TEMPERATURE GASES UNDER CONDITIONS OF INTENSE PHASE TRANSFORMATIONS
The processes of retardation and subsequent entrainment of droplets of size 50–500 μm of a polydisperse water flow by high-temperature (about 1100 K) gases are investigated by means of the "Particle Image Velocimetry" and "Interferometric Particle Imaging" optical methods, cross-correlation cameras, and pulsed lasers. The initial velocities of motion of water droplets and gases varied within the ranges 0.5–5 m/s and 0.5–2.5 m/s. The limiting relationships between the initial velocities and dimensions of droplets at which the conditions for the entrainment of them by a gas countercurrent fl ow are implemented established. A dimensionless criterion for prognostic evaluation of the retardation conditions and of the subsequent entrainment of water droplets by high-temperature gases under analyzed conditions is introduced into consideration.
Author: R. S. Volkov, G. V. Kuznetsov, and P. A. Strizhak
Keywords: water, droplets, polydisperse dropping liquid fl ow, high-temperature gases, phase transformations, entrainment
INFLUENCE OF BIOFUEL ADDITIONS ON THE IGNITION DELAY OF SINGLE DIESEL FUEL DROPS
The behavior of single drops of two- and three-component mineral diesel fuel blends with ethanol and rapeseed oil methyl ester in a heated atmosphere has been investigated. With the use of the known quasi-stationary approach, the infl uence of the thermal properties of fuel blend components and their composition on the ignition delay time of the drop has been investigated. It has been established that under inert heating conditions of the drop, additions of low-boiling ethanol to diesel fuel should shorten the duration of the preignition period, and additions of rapeseed oil methyl ester should, on the contrary, prolong it. Analysis of the obtained data has made it possible to determine the optimal composition of the fuel blend for the most economical operation of the diesel. The prognostic estimates made are confi rmed by laboratory experiments and bench tests of fuel blends.
Author: A. K. Kopeika, V. V. Golovko, A. N. Zolotko, L. Raslavičius, and V. M. Lubarskii
Keywords: biofuel, diesel fuel, fuel blend, drop, ignition, ignition delay time
STUDY OF THE PHYSICAL AND ENERGY PROPERTIES OF FUEL GRANULES BASED ON A THERMOMODIFIED WOOD RAW MATERIAL
The authors present the results of experimental studies of the basic properties of fuel granules that have been produced from wood raw material treated in different temperature regimes. The authors have established the infl uence of the temperature of pretreatment of the raw material on the hygroscopicity, swelling, fl ame-maintenance effi ciency, and heat of combustion of fuel granules. A comparative analysis of the energy effi ciency of torrefacted pellets and regular fuel granules has been made.
Author: R. R. Safi n, R. R. Khasanshin, A. L. Timerbaeva, and A. V. Safina
Keywords: biofuel, wood, fuel granules, pellets, torrefaction, biocoal, torreficate, energy efficiency
EXPERIMENTAL INVESTIGATIONS OF THE ENERGY AND ENVIRONMENTAL INDICES OF OPERATION OF A LOW-CAPACITY COMBINED GAS PRODUCER AND HOT-WATER BOILER
It has been shown that the introduction of combined gas producers and boilers on renewable energy sources is a pressing issue. A structural diagram of a low-capacity combined gas producer and boiler on renewable energy sources has been given; a bench and procedures for investigation and processing of results have been developed. Experimental investigations of the energy and environmental indices of a 40-kW combined gas producer and hotwater boiler burning wood have been carried out. Results of the experimental investigations have been analyzed. Distinctive features have been established and a procedure of thermal calculation of the double furnace of a lowcapacity combined gas producer and boiler burning solid fuel has been proposed. The calculated coeffi cients of heat transfer from the gases in the convection bank have been compared with the obtained experimental results. A calculation dependence for the heat transfer from the gases in convection banks of low-capacity hot-water boilers has been proposed. The quantities of harmful emissions from the combined gas producer and boiler on renewable energy sources have been compared with the existing Ukrainian and foreign standards. It has been established that the environmental effi ciency of the boiler under study complies with most of the standard requirements of European countries.
Author: L. A. Bodnar, D. V. Stepanov, and A. N. Dovgal′
Keywords: combined gas producer and boiler, double furnace, coeffi cient of heat transfer from the gases, correction factor, environmental indices, nitric oxide, carbon oxide
REFINED MODEL OF HEAT TRANSFER IN COMPOSITE BODIES REINFORCED WITH TUBES WITH A LIQUID HEAT-TRANSFER AGENT MOVING IN A DEVELOPED TURBULENT REGIME
The author has obtained equations describing thermal conductivity of composite bodies spatially reinforced with a system of smooth tubes in which an incompressible liquid heat-transfer agent is pumped in a developed turbulent regime. The corresponding boundary-value heat-conduction problem was formulated and its qualitative analysis was made. Specific calculations were performed for steady-state temperature fi elds in cylindrical concrete shells spirally reinforced with steel tubes through which a heat-transfer agent (air) is pumped. A study has been made of the influence of the reinforcement parameters and of the velocity and direction of the heat-transfer agent in the tubes and the dimensions of their cross sections on the temperature fi eld. It has been established that variation of these characteristics enables one to substantially change the intensity of heat removal from the shells, opening up wide opportunities for effi cient control of the heat transfer in them.
Author: A. P. Yankovskii
Keywords: heat conduction, composite structures, reinforcement with tubes, liquid heat-transfer agent, heat and mass transfer, structural model, turbulent flow.
MODELING OF THE TEMPERATURE AND STRESSED-STRAINED STATES OF THE REFLECTOR OF A MIRROR SPACE ANTENNA
Results of modeling of the temperature and stressed-strained states of the refl ector of a mirror space antenna installed on a spacecraft that conducts a fl ight on geostationary and low near-earth orbits have been presented.
Author: S. V. Reznik, P. V. Prosuntsov, and A. V. Azarov
Keywords: reflector, mirror space antenna, spacecraft, geostationary and low near-earth orbits
ON DETERMINATION OF INHOMOGENEOUS THERMOMECHANICAL CHARACTERISTICS OF A PIPE
Structures from inhomogeneous materials are widely used in various fields of technology with large thermomechanical loads. The effi ciency of use of such materials depends on the knowledge of exact laws of inhomogeneity, which requires solution of inverse coeffi cient thermoelasticity problems. In the present work, we give versions of statement of inverse thermoelasticity problems for an inhomogeneous cylindrical pipe. Investigation of the primal problem on radial oscillations of the pipe is reduced to solution of a system of ordinary differential equations of 1st order in Laplace transforms on the basis of the targeting method and the employment of the inversion technique implemented in accordance with the Durbin method. For solution of a nonlinear inverse problem on the basis of the linearization method, we construct an iterative process each stage of which is used for solution of the Fredholm integral equation of the 1st kind. Consideration is given to specifi c examples of reconstruction of thermomechanical characteristics of an inhomogeneous cylinder. Computational experiments show the effi ciency of this approach to reconstruction of different inhomogeneity laws.
Author: A. O. Vatul′yan and S. A. Nesterov
Keywords: inverse coeffi cient problem, thermoelasticity, pipe
EFFECT OF TEMPERATURE AND DENSITY VARIATIONS ON THERMAL CONDUCTIVITY OF POLYSTYRENE INSULATION MATERIALS IN OMAN CLIMATE
The thermal and energy performance of buildings depends on the thermal characteristics of the building envelope and particularly on the thermal resistance of the insulation material used. The ability of a thermal insulation material to transmit heat in the presence of a temperature gradient is determined by its thermal conductivity. The thermal conductivity values of building insulation materials are generally given at 24oC according to ASTM standards. Actually, such a material when used in a building envelope is exposed to signifi cant and continuous temperature changes, essentially due to the changes in outdoor temperature and solar radiation, especially in harsh climate. The main objective of this study is to investigate the relationship between the temperature and the thermal conductivity of polystyrene, which is widely employed as a building insulation material in Oman, at various densities, using the developed experimental setup based on the guarded hot plate method. The results show that higher temperatures lead to higher thermal conductivities and the lower is the material density, the higher is the thermal conductivity. The envelope-induced cooling load for a simple building is also calculated, and it is shown that a lesser cooling load is needed for a high-density insulation.
Author: M. Khoukhi and M. Tahat
Keywords: building insulation, thermal conductivity, polystyrene, cooling load
SIZE EFFECTS IN THE COURSE OF TRAPPING IMPURITY ATOMS BY NANOPARTICLES GROWING IN A SUPERSATURATED VAPOR
The infl uence of size effects on the coeffi cient of trapping impurity atoms by a growing nanoparticle as well as on the concentration of impurity atoms in it is studied theoretically.
Author: V. V. Levdansky, J. Smolik, V. Zdimal, and P. Moravec
Keywords: nanoparticles, condensation, impurity, trapping coeffi cient, size effects
PRODUCTION OF AMORPHOUS AND NANOCRYSTALLINE SILICON FILMS BY THE HOT-WIRE ACTIVATION METHOD
Thin fi lms of amorphous silicon with inclusions of a nanocrystalline silicon phase have been obtained by the method of gas-phase chemical deposition with hot-wire activation of the precursor. The influence of the gas pressure and of the hydrogen–monosilane ratio on the rate of growth and the degree of crystallinity of the deposited silicon has been investigated. Characteristic values of the synthesis parameters for obtaining silicon fi lms of various degrees of crystallinity have been established.
Author: M. N. Andreev, A. K. Rebrov, A. I. Safonov,a N. I. Timoshenko, K. V. Kubrak, and V. S. Sulyaeva
Keywords: gas-phase chemical deposition with hot-wire activation, thin silicon fi lms, amorphous silicon, nanocrystalline silicon
CHARACTERISTIC FEATURES OF THE THERMOPHYSICAL PROPERTIES OF A SYSTEM BASED ON POLYETHYLENE OXIDE AND CARBON NANOTUBES
The results of experimental and computational investigations of the thermophysical characteristics of polymer nanocomposites based on polyethylene oxide and carbon nanotubes are presented. It has been established that the thermal conductivity of a system depends substantially on the structure of the polymer matrix and content of nanotubes. It is shown that the thermal conductivity displays percolation behavior and is described within the framework of the percolation theory. The percolation threshold equals 0.6%. It has been revealed that before the percolation threshold the thermal conductivity correlates well with the degree of crystallinity of the polymer matrix.
Author: É. A. Lysenkov and V. V. Klepko
Keywords: polymer nanocomposites, percolation behavior, carbon nanotubes, thermal conductivity, degree of crystallinity
APPROXIMATE KINETIC ANALYSIS OF INTENSE EVAPORATION
An approximate kinetic analysis of the process of intense evaporation has been carried out. The analytical solutions obtained for temperatures, pressures, and mass velocities of vapor agree well with the available numerical and analytical solutions. The evaporation limiting mass velocity has been calculated.
Author: Yu. B. Zudin
Keywords: kinetic analysis, intense evaporation, analytical solution, limiting mass velocity
DEFORMATION OF A STEP COMPOSITE BEAM IN A TEMPERATURE FIELD
Consideration is given to thermal force deformation of an elastic three-layer beam with a stepwise thickness of one supporting layer. To describe the kinematics of a rod that is asymmetric across the bundle, the hypotheses of a broken normal are adopted. A system of equilibrium equations is derived and its general analytical solution in displacements is obtained. A numerical parametric analysis of the stressed-strained state of a metal-polymer threelayer beam is carried out.
Author: É. I. Starovoitov, Yu. M. Pleskachevskii, D. V. Leonenko, and D. V. Tarlakovskii
Keywords: temperature, deformation, composite beam, step thickness
NONLINEAR EFFECTS IN MSM STRUCTURES BASED ON Ag4SSe
MSM structures W–Ag4SSe–W have been produced and their volt–ampere characteristics in the temperature range 290–350 K and at a temperature of 77 K were investigated. It is shown that the volt–ampere characteristic of such an MSM structure is substantially nonlinear and takes an N-like shape at different polarities of the voltage applied to the structure and that the portion of this characteristic corresponding to the negative resistance of the structure is preceded by the portion with a zero slope. It was established that the breakdown voltage of the volt– ampere characteristic of an W–Ag4SSe–W structure is determined by its temperature and is equal to ~0.3 V, which corresponds to the strength 1 V/cm of the electric field in it, and that the breakdown current of the structure changes by the law I ~ T 0.25 with increase in its temperature. The nonlinearity of the volt–ampere characteristics with a negative-resistance portion of the W–Ag4SSe–W structures obtained is explained by the existence of the trapping level in them at a certain state of the electrons at the metal–semiconductor interface
Author: G. S. Gadzhieva, I. A. Akhmedov, and N. N. Abdul-zade
Keywords: MSM structure, volt–ampere characteristic, negative resistance
REGRESSION ALGORITHM USING THE RANK MEASURE
A method for extending the uncertainty paradigm to regression analysis is presented. The properties of the rankmeasure-based algorithm as applied to the classical parametric regression problem are analyzed. The rank measure algorithm is compared with other uncertainty recalculation algorithms and the classical criteria regression algorithms.
Author: E. V. Chernukho
Keywords: parametric regression models, rank measure, uncertainty