HEAT AND MASS TRANSFER IN DISPERSE AND POROUS MEDIA

COALESCENCE OF AN ENSEMBLE OF NANOPARTICLES IN

A FEMTOLITER DROPLET OF SUPERSATURATED SOLUTION

S. P. Fisenko and Yu. A. Khodyko

UDC 536.423

A numerical analysis of coalescence and growth of an ensemble of nanoparticles on colloid precursors in a

femtoliter droplet was carried out. It is shown that the supersaturation of a solution inside the droplet occurs

due to the evaporative cooling of droplets in an aerosol reactor at a lowered pressure. It has been proved

that in the medium field approximation, particles grow stably only on largest precursors. At short times the

distribution function of nanoparticles is of more complex character.

Keywords: diffusion, medium field approximation, Kelvin effect.

PAGE 487

INFLUENCE OF MAGNETIC AND ACOUSTIC TREATMENT

OF SUPERPLASTICIZER SOLUTIONS ON THE PROPERTIES

OF PORTLAND CEMENT CONCRETES

N. Kh. Belous,^{a} V. V. Azharonok,^{b} S. P. Rodtsevich,^{a}

V. D. Koshevar,^{a} S. V. Goncharik,^{b} N. I. Chubrik,^{b}

A. I. Orlovich,^{c} and V. V. Rubannik^{d}

UDC 666.97.001.015:[53.09+53.06]

We have investigated the influence of the regimes of high-frequency magnetic-impulse and acoustic action on

the physicochemical properties of water solutions of polycarboxylate superplasticizers and technological indices

of fine concretes plasticized by them. The dependences of technological properties of concretes on the

concentration of water solutions of the superplasticizers, the content of impurity ions in the water used for

dilution, and the conditions of acousto-radiowave treatment have been determined. The regimes of activation

of superplasticizer solutions, which permit increasing the mobility and keeping quality of concrete and solution

mixes tempered with water and the density and strength of fine concretes formed from them, have been

established.

Keywords: tempering liquid, superplasticizers, electromagnetic and acoustic activation, portland cement, concretes,

density, compression strength, mobility, index of activity of hydrogen ions, surface tension, shear stress,

dynamic viscosity.

PAGE 493

OBTAINING CARBON SUSPENSIONS

BY THE HYDROMECHANICAL METHOD

O. G. Martynenko, A. A. Bulavko, A. V. Suvorov,

A. V. Vlasov, L. A. Senchuk*, and M. I. Rusakevich

UDC 536.46

This paper presents the results of an investigation of the process of obtaining carbon suspensions with a fraction

of carbon particles of size less than a micrometer by the hydromechanical method with the use of a

gear-type pump and two rotor-type pulsation pulverizers.

Keywords: coal-water slurry, hydromechanical treatment, cavitation.

PAGE 501

MODELING OF THE PROCESS OF TWO-PHASE

TRANSPIRATION COOLING IN THE PRESENCE

OF PERIODIC PERTURBATIONS

A. N. Golovanov and A. S. Yakimov

UDC 536.46:536.245.022

Consideration is given to the interaction between a system of two-phase transpiration cooling and a high-enthalpy

pulsating gas flow. A study is made of the influence of the process of phase transformation on the

characteristics of heat and mass exchange and on the possibility of controlling the process of heat exchange

in a thermal protective material.

Keywords: two-phase cooling, thermal protective material, pulsating gas flow, heat and mass exchange.

PAGE 505

ON CALCULATION OF FILTRATION FLOWS

FROM SPRAYERS OF IRRIGATION SYSTEMS

E . N. Bereslavskii

UDC 532.546

In the hydrodynamic formulation, consideration is given to plane steady filtration in a homogeneous isotropic

ground from sprayers through a soil layer underlain by a highly permeable pressure water-bearing formation

in the presence of the ground capillarity and evaporation from the free surface. Filtration is studied by formulating

a mixed multiparametric boundary-value problem of the theory of analytical functions, which is

solved using the Polubarinova-Kochina method and procedures of conformal mapping of the regions of special

kind that are characteristic of underground-hydromechanics problems. On the basis of the model proposed,

an algorithm of computation of capillary water spread and filtration flow rate was developed in

situations where in the water filtration from sprayers, account is taken of the ground capillarity, evaporation

from the free surface, and of the upthrust from the side of the underlying well-permeable formation. With the

aid of the exact analytical dependences obtained and of numerical calculations, a hydrodynamic analysis is

performed for the structure and characteristic features of the modeled process, and for the influence of all

physical parameters of the scheme on the filtration characteristics. Consideration is given to the limiting and

particular cases associated with the absence of separate factors characterizing the modeled process, such as

the ground capillarity, evaporation from the free surface, and the upthrust from the side of the underlying

water-bearing highly permeable layer. Calculated results for filtration from canals with identical filtration

characteristics and similar filtration schemes are compared.

Keywords: filtration, sprayer, groundwater, pressure underground water, ground capillarity, evaporation from

the free surface, complex flow velocity, conformal mappings, Polubarinova-Kochina method.

PAGE 516

HEAT EXCHANGE IN A RING GRANULAR BED

Yu. S. Teplitskii and M. V. Vinogradova

UDC 532.546

On the basis of a theoretical model of heat exchange in a granular bed, a simple dependence has been obtained

for calculation of the heat-exchange coefficient in an extended ring bed. A comparison the dependence

and the available experimental data has been made.

Keywords: ring granular bed, heat-exchange coefficient, model of heat exchange, active heat insulation, air

heater.

PAGE 539

HYPERBOLIC MODEL OF A MULTIVELOCITY

HETEROGENEOUS MEDIUM

V. S. Surov

UDC 532.529.5

The model of a multivelocity multicomponent medium, which is based on the conservation laws and whose

equations belong to a hyperbolic type, has been presented. A number of problems on disintegration of an arbitrary

discontinuity in a dust-laden gas have been calculated with the Courant–Isaacson–Rees numerical

method.

Keywords: multicomponent multivelocity medium, hyperbolic systems of partial differential equations, numerical

modeling.

PAGE 530

NANOSTRUCTURES

HEAT AND MASS TRANSFER IN THE SYSTEM

HYDROCARBON GAS–POROUS CARBON LAYER–METAL

AND FORMATION OF SUPERSATURATED SOLID CARBON

SOLUTIONS

D. A. Takopulo and S. P. Fisenko

UDC 536.248

It is shown that the carbon layer formed on the catalytic surface of a metal plays an important role in industrial

technologies of obtaining carbon nanofibers. The effective heat conduction of porous carbon samples

was measured. A mathematical model of the heat and mass transfer inside a carbon layer has been developed

and its stationary solutions were investigated. It is shown that a decrease in the thickness of a porous carbon

layer on the surface of a metal as a result of its cleaning and a further growth of this layer lead to the formation

of a supersaturated solid solution of carbon in the metal.

Keywords: effective heat conduction of a porous layer, diffusion of carbon, time of establishment of a stationary

regime, Pade′ approximation, solubility of carbon in a metal.

PAGE 539

PYROLYSIS OF A FEMTOLITER DROP

IN A LOW-TEMPERATURE AEROSOL

REACTOR AT A LOWERED PRESSURE

K. I. Delendik, V. I. Saverchenko,

and S. P. Fisenko

UDC 536.423

The products of low-temperature pyrolysis of a solute in the rapid evaporation of droplets of an aqueous solution

of NiCl2 in an aerosol reactor, were found experimentally. An x-ray spectroscopic analysis has shown

that approximately 37% of nickel atoms pass into oxides. The pyrolysis products possess residual magnetization.

It is also found that the rate of evaporation of nickel and chlorine compounds depends on the radius of

droplets and their mass flow rate.

Keywords: evaporation, nanoparticles, nickel oxide, supersaturated solution, galvanoplastics, x-ray spectroscopic

analysis.

PAGE 549

HEAT AND MASS TRANSFER IN COMBUSTION PROCESSES

ON THE POSSIBILITY OF ENHANCING

THE RATE OF COMBUSTION OF GASES

AND GASEOUS MIXTURES

Yu. V. Polezhaev, O. G. Stonik,

and G. V. Gabbasova

UDC 536.461; 536.25

A classification of combustion regimes is given. The influence of various factors on the combustion rate and

height of a flame is shown. Relationships for determining the rates of laminar and turbulent combustion of a

fuel are given.

Keywords: combustion regimes, flame height, scale of turbulent combustion.

PAGE 554

METHOD FOR CHARACTERIZING AND CHOOSING

THE SOLID MIXED FUEL FOR MICROTHRUSTERS

OF MICROELECTROMECHANICAL SYSTEMS

S. I. Futko,^{a} V. P. Bondarenko,^{b,}

and L. N. Dolgii^{b}

UDC 662.612.2.662.311.1

We propose a method for characterizing and choosing solid mixed fuels for use as the solid-fuel charge of

microthrusters of microelectromechanical systems. The method is based on the solution of the problem on the

dependence of impulse responses of such a microthruster on the diameter of the outlet cross-section of its

combustion chamber and the microkinetic parameters of the fuel. The variants of choosing the above fuels

have been illustrated using glycidyl azide polymer/RDX as the example of a solid fuel mixture. The paper presents

the characteristic criteria determining the composition of mixed fuels for the microthruster of a microelectromechanical

system and considers the main types of "direct" and "inverse" problems arising in

characterizing and choosing such fuels.

Keywords: solid rocket fuel, solid fuel combustion, macrokinetic modeling, solid-fuel rocket engine, microthruster,

thermodynamics, mixed fuel, solid-fuel charge, glycidyl azide polymer, RDX, method, impulse.

PAGE 558

MODELING OF THE PROCESS OF BURNING-OUT

OF COKE–ASH PARTICLES IN A FLUIDIZED BED

B. B. Rokhman UDC 532.529:532.517.4

A generalized statistical model of the process of burning out of coal particles in a fluidized-bed furnace is

constructed. It takes into account the kinetics of heterogeneous chemical reactions, as well as radiant and

convective–conductive heat transfer, which made it possible to considerably expand the region of application

of the existing models. Different schemes of the behavior of ash in the process of burning of carbon particles

are considered. Boundary conditions (conditions of matching) were formulated, and analytical solutions for

the distribution function of particles in small intervals of carbon concentration for surface and bulk reaction

have been obtained.

Keywords: distribution function, combustion, particle, gas, polydispersity, temperature, heterogeneous reaction,

concentration, velocity, aerodynamics, fluidized bed.

PAGE 565

MICROWAVE TECHNOLOGIES IN COAL POWER ENGINEERING

V. V. Salomatov,^{a,c} S. O. Sladkov,^{b}

and S. E′. Pashchenko^{c}

UDC 621.311

An analysis of the modern state and prospects of using microwave radiation in the processes of drying, dispersion,

burning, and fine processing of low-rank coals for the purpose of increasing the energy efficiency of

coal technologies and decreasing harmful emissions from them has been carried out. It is shown that the use

of microwave-radiation energy in coal power engineering is a promising method of complex action on coal in

the process of its preparation and burning.

Keywords: microwave radiation, coal, drying, heating, dispersion, cleaning, ignition, burning, processing.

PAGE 576

TRANSFER PROCESSES IN A LOW-TEMPERATURE PLASMA

INFLUENCE OF CLUSTERING ON THE EFFECTIVE

ADIABATIC EXPONENT OF A LOW-TEMPERATURE

CARBON PLASMA

N. I. Alekseev,^{a,b} B. I. Reznikov,^{a} B. G. Zhukov,^{a}

S. V. Bobashev,^{a} S. A. Ponyaev,^{a} and R. O. Kurakin^{a}

UDC 532.525, 537.523

Calculation of the equilibrium composition and the effective adiabatic exponent of a low-temperature carbon

plasma containing neutral and charged carbon clusters up to the clusters C15 has been carried out. The

range of temperatures and pressures at which carbon atoms associate into multiatomic clusters has been determined.

It has been shown that the effective adiabatic exponent of carbon plasma is a composite nonmonotonic

function of temperature, which has a substantial effect on the flow of a carbon-plasma jet out of

channels and on plasma-flux flow past various obstacles.

Keywords: railtron, rail accelerator, plasma jet, carbon clusters.

NUMERICAL MODELING OF ARC PLASMA

GENERATOR FOR CHEMICAL LASER APPLICATIONS

Vidya Sagar,^{a} Chhaya Ravikant,^{b}

Gaurav Singhal,^{a} and Alok P. Mittal^{c}

UDC 535.2/.3+621.375

The results of the numerical modeling of arc discharge phenomenon relevant to hydrogen fluoride/deuterium

fluoride (HF/DF) laser applications are given. The overall mechanics of arc discharge phenomena on the

basis of numerical modeling employing the commercial code COMSOL is discussed. The equations for a 2D

axisymmetric, weakly compressible, laminar flow with heat transfer and the coupled hydrodynamic and electromagnetic

equations are solved using the SIMPLE algorithm. The variations in the material properties, temperature,

and velocity due to the generated arc are studied. A comparison of the results obtained with those

from the studies available in the literature validates the computational data. Since each designed plasma arc

tunnel is unique in itself and specific in application, this would enable one to alter arc discharge parameters

to optimize a specific laser.

Keywords: HF/DF, arc plasma generator, COMSOL.

PAGE 605

HYDROGASDYNAMICS IN TECHNOLOGICAL PROCESSES

MODELING OF REFLECTION OF DETONATION

AND SHOCK WAVES FROM A RIGID WALL

IN MIXTURES OF A REACTIVE GAS

AND CHEMICALLY INERT PARTICLES

A. V. Fedorov,^{a} P. A. Fomin,^{b}

D. A. Tropin,^{a} and J.-R. Chen^{c}

UDC 534.222

An algorithm of approximate calculation of the reflection of detonation waves in mixtures of a reactive gas

and chemically inert microparticles has been proposed. Consideration has been given to the case where the

gas behind the wave front is in chemical equilibrium (D → D reflection). It has been shown that the presence

of the condensed phase can substantially decrease the parameters of the reflected wave (its velocity, pressure,

and temperature). Within the framework of a one-dimensional nonstationary approach and with allowance for

the detailed kinetics of chemical reactions, the evolution of the shock wave in a stoichiometric hydrogen-oxygen

mixture with sand particles in its reflection from a rigid wall has been calculated. The limiting particle

concentration below which the reflected wave is of the detonation type and above which it is of the shock

type has been found.

Keywords: suppression of gaseous detonation, gas-particles mixture, explosion safety.

PAGE 614

NUMERICAL SIMULATION OF THE SELF-ORGANIZATION

OF CONVECTIVE STRUCTURES IN A THIN LAYER OF LIQUID

I. N. Shishkova, V. Yu. Levashov,

and A. P. Kryukov

UDC 532.527

Complex convective structures observed experimentally in a thin layer of liquid are investigated numerically.

To study this kind of phenomena, a mathematical model is suggested based on the interaction of two such opposite

factors as the randomness of convective motions in the medium of interest as a whole and intensification

of these motions by local sources that introduce correlations into a random process. The results obtained

by mathematical simulation qualitatively reflect the most characteristic phenomena noted in the experiments.

Keywords: convective structures, numerical simulation, thin liquid layer.

CONDUCTION–CONVECTION–RADIATION EFFECTS

ON THE FLOW OF OPTICALLY DENSE GRAY FLUID

OVER A HORIZONTAL CIRCULAR DISK

S. Siddiqaa and M. A. Hossainb

UDC 536.25

A natural convection boundary-layer flow of an optically dense gray viscous fluid (liquid metal) above a horizontal

circular disk with regard to thermal radiation is discussed. The radiative heat flux term is expressed

by using the optically thick radiation limit. The corresponding boundary-layer equations are solved with the

aid of three distinct numerical techniques: the straightforward finite difference (SFD) method is employed to

solve the problem directly, and then the stream function formulation (SFF) and primitive variable formulation

(PVF) methods based on solving transformed equations are used. The numerical results are interpreted in

terms of the local skin friction coefficient and the local Nusselt number. The influence of the problem parameters

on these characteristics is shown.

Keywords: natural convection, thermal radiation, horizontal circular disk.

LOCAL THEORY OF PARALLEL APPROACH

OF PLATES IN AN INCOMPRESSIBLE LIQUID

S. K. Betyaev

UDC 532.526.2

A flow of an incompressible liquid in a thin layer between two approaching disks or plates located in parallel,

at the final stage of their symmetrical approach, is considered. It is assumed that the velocity of the body

is assigned as a function of time. An inspection analysis of the problem has been made: the types of flows

depending on the law of approaching plates and the conditions under which the pressure in the layer and,

consequently, the acting forces increase infinitely have been determined. Approximate solutions in the plane

and axisymmetric cases are suggested. Exact solutions have been obtained for infinitely small and infinitely

high Reynolds numbers.

Keywords: incompressible liquid, law of approaching plates, viscous flow regime, highly viscous flow regime,

inviscid flow regime.

STERNBERG–KOITER PARADOX IN

PROBLEMS ON INVISCID FLOW OF FLUID

S. K. Betyaev

UDC 532.526.5

The problem on inviscid flow of fluid inside a wedge when the Sternberg–Koiter paradox takes place has

been considered. The flow is divided into potential and vortex and stationary and nonstationary ones. A resolution

of the paradox is given.

Keywords: singularity, bifurcation, self-similarity, superposition.

SOME TWO-DIMENSIONAL FLOWS WITH COUPLE STRESSES

M. Sajid,a N. Ali,b Z. Abbas,b

T. Javed,b and M. Imranc

UDC 532.5

The effect of couple stresses on some two-dimensional flows is considered. The numerical solutions are obtained

by the shooting method using the Runge–Kutta algorithm in the four flow problems for a couple stress

fluid, namely, for the Blasius, Sakiadis, stretching, and stagnation-point flows. The obtained solutions are nonsimilar

for the Blasius and Sakiadis flows. The results are interpreted concerning the influence of the couple

stress parameter which is a measure of the polarity of a fluid. It is shown that for large values of this parameter

the solution converges to the solution for a Newtonian fluid.

Keywords: two-dimensional flow, couple stresses, Blasius flow, Sakiadis flow, stretching flow, stagnation-point

flow, numerical solution.

TRANSFER PROCESSES IN RHEOLOGICAL MEDIA

RHEOLOGY DYNAMICS OF THE BLOOD AND PLASMA

OF RATS AFTER TRANSDERMAL LASER IRRADIATION

OF THE TAIL VEIN IN THE INFRARED RANGE

I. V. Yamaikina,a V. A. Mansurov,b N. B. Gorbunova,c

L. E. Batai,d V. S. Ulashchik,c and V. A. Orlovichd

UDC 577.344.3

Single transdermal laser irradiation of the tail vein of males of white mongrel rats with an average mass of

350–400 g in three different regimes has been carried out. The irradiation doses were chosen to be intermediate

between therapeutic and surgical ones, and the radiation wavelengths were 806 nm and 2 μm. The dynamics

of the packed cell volume, deformability and cytometric indices of erythrocytes, and of the plasma and

blood viscosity have been investigated. The rheological and cytometric changes in the blood caused by the irradiation

stayed for several days. The observed rheologial changes are due to the removal of irradiation-damaged

erythrocytes and the arrival in the blood channel of young and highly deformable red cells.

Keywords: viscosity, blood, plasma, deformability of erythrocytes, infrared spectral range, laser irradiation.

RHEOLOGICAL PROPERTIES OF DISPERSE SYSTEMS

BASED ON HYDROLYZED LIGNIN AND OIL

T. A. Savitskaya,a I. V. Reznikov,a V. A. Shcheglov,a

N. G. Tsygankova,b G. M. Telysheva,c and D. D. Grinshpanb

UDC [66.081.3+665.7]:634.0.864

The rheological properties of oil dispersions of hydrophobized hydrolyzed lignin, which is an effective sorbent

of oil and oil products, have been studied. It has been shown that at a lignin concentration of over 10%,

free-disperse systems with Newton flow go over to coagulation thixotropic structures, demonstrating the

pseudoplastic character of flow. The structural-mechanical characteristics of highly filled (lignin content of

40–45%) dispersions have been determined and the concentration region of existence of an oil-saturated sorbent

in the form of a solid product easily removed from the water surface has been established.

Keywords: rheological properties, oil, lignin, dispersion.

MATHEMATICAL MODELING OF THE FORMATION

OF CLOTS IN BLOOD VESSELS

E ′

. M. Khramchenkov and M. G. Khramchenkov UDC 532.546

A mathematical model of the formation of a clot (thrombosis) has been constructed in which the fibrin of the

clot is considered as an elastically deformable solid phase of variable mass and the prothrombin, thrombin,

fibrinogen, and fibrin monomers as components of the liquid phase. As a result of numerical solution of the

model, data on the influence of various parameters of the process of thrombosis on the rate of clot formation

have been obtained.

Keywords: blood vessels, clot, thrombosis, vessel wall, thrombin, prothrombin, fibrinogen, fibrin network.

HEAT CONDUCTION AND HEAT EXCHANGE IN TECHNOLOGICAL PROCESSES

ON THE INFLUENCE OF ASYMMETRY ON THE VELOCITY

OF MOTION OF ISOTHERMS NEAR THE THERMAL CENTER

OF A COOLED BODY

V. V. Vinogradov,a I. L. Tyazhel’nikova,a

and E. P. Vinogradovab

UDC 536.2

A study has been made of the influence of asymmetric cooling of bodies due to the temperature difference on

the surfaces, the difference in thermophysical characteristics of the media, and the geometry of the body on

the velocity of motion of isotherms as they approach the thermal center. The results have been used for elucidation

of the causes of certain thermophysical features appearing when continuously cast ingots solidify in

horizontal continuous casting plants and when the bloom molds are replaced by slab molds in continuous

ingot casting machines. An analytical expression for the displacement of the thermal center of a plate in formation

of media with different thermal-diffusivity coefficients has been obtained.

Keywords: cooling of an ingot, velocity of motion of isotherms, thermal center, asymmetry, heat-conduction

equation, solidification of a continuously cast ingot, thermal diffusivity.

ANISOTROPY OF THERMAL CONDUCTIVITY

OF FERRO-FILLED POLYVINYLCHLORIDE

B. B. Kolupaev UDC 541.64:532.72

The contribution of the constant external magnetic field to the anisotropy of thermal conductivity of polyvinylchloride

(PVC) containing powders of highly dispersed ferromagnetics (iron and magnetite) as a filler has

been determined. The relationship between the thermal conductivity coefficient of such PVCs, the direction of

the heat-flux vector, and the normal to the isotherm of the composite has been established. It has been shown

that for the systems "PVC + 2.0 vol. % Fe" and "PVC + 2.0 vol. % Fe3O4" formed on exposure to an external

magnetic field, the value of the principal axes of the thermal-conductivity coefficient depends on the

type of filler. A comparison of the calculated and experimental values of the sought quantities has been made.

Keywords: anisotropy, magnetite, heat conduction, heat flux.

TOWARDS THE DYNAMICS OF THE TEMPERATURE FIELD

GRADIENT IN A LAYER OF AN INORGANIC MATERIAL

UNDER RADIATION HEATING ACCORDING TO THE DATA

OF EXPERIMENTS AND NUMERICAL MODELING

V. R. Sobol,a P. N. Goman,b

and O. N. Mazurenkoc

UDC 536.331

We have investigated the process of temperature field formation in a layer of a weakly conducting medium

with the example of wood and green moss under irradiation of one side with an energy flux and contact heat

removal through the opposite back surface of the material onto an asbestos-cement support. The experimental

results were compared with the data calculated on the basis of the relations of nonstationary heat transfer in

the approximations of closeness and openness of the system. The conditions for heat removal suppression have

been concretized and the role of the energy exchange under the prolonged action of radiant energy for estimating

the thermal stability parameters of related materials has been elucidated. The obtained data can be

used to control radiant fluxes in treating wood, for effective heating of living and industrial premises, improving

the methods for opposing high energy fluxes, and preventing the propagation of fire in inhabited localities

and in park and forest zones.

Keywords: temperature, temperature gradient, heat flow, heat conductivity, heat capacity, heating, heat removal,

green moss, flammability.

THERMAL AND NEUTRON-PHYSICAL FEATURES

OF THE NUCLEAR REACTOR FOR A POWER

PULSATION PLANT FOR SPACE APPLICATIONS

E ′

. G. Gordeev,a A. S. Kaminskii,a G. V. Konyukhov,b

V. A. Pavshuk,b and T. A. Turbinaa

UDC 621.039.5

We have explored the possibility of creating small-size reactors with a high power output with the provision

of thermal stability and nuclear safety under standard operating conditions and in emergency situations. The

neutron-physical features of such a reactor have been considered and variants of its designs preserving the

main principles and approaches of nuclear rocket engine technology are presented.

Keywords: nuclear power plant, nuclear rocket engine, modular design, energy production, thermal stability,

nuclear safety, reactivity effects, burnable neutron poison, fission density.

INVESTIGATION OF THE PHOTOELECTRIC

CHARACTERISTICS OF PHOTODIODE STRUCTURES

WITH SILICON-BASED POTENTIAL BARRIERS

O. A. Abdulkhaev, G. O. Asanova,

D. M. Yodgorova, and A. V. Karimov

UDC 621.383.52:535.243

Based on silicon with a base region thickness of 300 μm, phototransforming Au–nSi–Au structures with potential

barriers are prepared. The diode structures obtained possess high photosensitivity in the spectral region

0.9–1.1 μm at low illumination intensities of 10 lux (up to 5 A/W). Based on investigations of the

photoelectric characteristics, it has been established that the Au–nSi–Au structures in the range of temperatures

from room temperature to 40oC at low working voltages (0.1–0.2 V) are distinguished by the weak temperature

dependence of photocurrents. In principle, in the spectral range 0.7–1.1 μm the Au–nSi–Au

structures obtained can easily replace both gallium arsenide and classical silicon photodiodes with one rectifying

junction in optoelectronic devices.

Keywords: photoelectric characteristics, photocurrent, potential barriers, base region, silicon, photodiode structure.

REFLECTIONLESS TRANSMISSION OF ELECTROMAGNETIC

RADIATION THROUGH A MAGNETIC–DIELECTRIC SYSTEM

G. A. Mamedov, E′. G. Ismibeili,

and S. R. Kasimova

UDC 621.365

The conditions and frequency band of reflectionless transmission of electromagnetic radiation through a plane

absorbing layer of a magnet that separates two semi-infinite nonabsorbing dielectric media have been found.

The dependence of these conditions on the separating layer thickness, magnetic and dielectric properties of

the layer substance, and of the adjacent substrate is investigated.

Keywords: absorption of electromagnetic wave, magnetic coating, dielectric substrate.

HEAT AND MASS TRANSFER IN DISPERSE AND POROUS MEDIA

COALESCENCE OF AN ENSEMBLE OF NANOPARTICLES IN

A FEMTOLITER DROPLET OF SUPERSATURATED SOLUTION

S. P. Fisenko and Yu. A. Khodyko UDC 536.423

A numerical analysis of coalescence and growth of an ensemble of nanoparticles on colloid precursors in a

femtoliter droplet was carried out. It is shown that the supersaturation of a solution inside the droplet occurs

due to the evaporative cooling of droplets in an aerosol reactor at a lowered pressure. It has been proved

that in the medium field approximation, particles grow stably only on largest precursors. At short times the

distribution function of nanoparticles is of more complex character.

Keywords: diffusion, medium field approximation, Kelvin effect.

INFLUENCE OF MAGNETIC AND ACOUSTIC TREATMENT

OF SUPERPLASTICIZER SOLUTIONS ON THE PROPERTIES

OF PORTLAND CEMENT CONCRETES

N. Kh. Belous,a V. V. Azharonok,b S. P. Rodtsevich,a

V. D. Koshevar,a S. V. Goncharik,b N. I. Chubrik,b

A. I. Orlovich,c and V. V. Rubannikd

UDC 666.97.001.015:[53.09+53.06]

We have investigated the influence of the regimes of high-frequency magnetic-impulse and acoustic action on

the physicochemical properties of water solutions of polycarboxylate superplasticizers and technological indices

of fine concretes plasticized by them. The dependences of technological properties of concretes on the

concentration of water solutions of the superplasticizers, the content of impurity ions in the water used for

dilution, and the conditions of acousto-radiowave treatment have been determined. The regimes of activation

of superplasticizer solutions, which permit increasing the mobility and keeping quality of concrete and solution

mixes tempered with water and the density and strength of fine concretes formed from them, have been

established.

Keywords: tempering liquid, superplasticizers, electromagnetic and acoustic activation, portland cement, concretes,

density, compression strength, mobility, index of activity of hydrogen ions, surface tension, shear stress,

dynamic viscosity.

OBTAINING CARBON SUSPENSIONS

BY THE HYDROMECHANICAL METHOD

O. G. Martynenko, A. A. Bulavko, A. V. Suvorov,

A. V. Vlasov, L. A. Senchuk*, and M. I. Rusakevich

UDC 536.46

This paper presents the results of an investigation of the process of obtaining carbon suspensions with a fraction

of carbon particles of size less than a micrometer by the hydromechanical method with the use of a

gear-type pump and two rotor-type pulsation pulverizers.

Keywords: coal-water slurry, hydromechanical treatment, cavitation.

MODELING OF THE PROCESS OF TWO-PHASE

TRANSPIRATION COOLING IN THE PRESENCE

OF PERIODIC PERTURBATIONS

A. N. Golovanov and A. S. Yakimov UDC 536.46:536.245.022

Consideration is given to the interaction between a system of two-phase transpiration cooling and a high-enthalpy

pulsating gas flow. A study is made of the influence of the process of phase transformation on the

characteristics of heat and mass exchange and on the possibility of controlling the process of heat exchange

in a thermal protective material.

Keywords: two-phase cooling, thermal protective material, pulsating gas flow, heat and mass exchange.

ON CALCULATION OF FILTRATION FLOWS

FROM SPRAYERS OF IRRIGATION SYSTEMS

E ′

. N. Bereslavskii UDC 532.546

In the hydrodynamic formulation, consideration is given to plane steady filtration in a homogeneous isotropic

ground from sprayers through a soil layer underlain by a highly permeable pressure water-bearing formation

in the presence of the ground capillarity and evaporation from the free surface. Filtration is studied by formulating

a mixed multiparametric boundary-value problem of the theory of analytical functions, which is

solved using the Polubarinova-Kochina method and procedures of conformal mapping of the regions of special

kind that are characteristic of underground-hydromechanics problems. On the basis of the model proposed,

an algorithm of computation of capillary water spread and filtration flow rate was developed in

situations where in the water filtration from sprayers, account is taken of the ground capillarity, evaporation

from the free surface, and of the upthrust from the side of the underlying well-permeable formation. With the

aid of the exact analytical dependences obtained and of numerical calculations, a hydrodynamic analysis is

performed for the structure and characteristic features of the modeled process, and for the influence of all

physical parameters of the scheme on the filtration characteristics. Consideration is given to the limiting and

particular cases associated with the absence of separate factors characterizing the modeled process, such as

the ground capillarity, evaporation from the free surface, and the upthrust from the side of the underlying

water-bearing highly permeable layer. Calculated results for filtration from canals with identical filtration

characteristics and similar filtration schemes are compared.

Keywords: filtration, sprayer, groundwater, pressure underground water, ground capillarity, evaporation from

the free surface, complex flow velocity, conformal mappings, Polubarinova-Kochina method.

HEAT EXCHANGE IN A RING GRANULAR BED

Yu. S. Teplitskii and M. V. Vinogradova UDC 532.546

On the basis of a theoretical model of heat exchange in a granular bed, a simple dependence has been obtained

for calculation of the heat-exchange coefficient in an extended ring bed. A comparison the dependence

and the available experimental data has been made.

Keywords: ring granular bed, heat-exchange coefficient, model of heat exchange, active heat insulation, air

heater.

HYPERBOLIC MODEL OF A MULTIVELOCITY

HETEROGENEOUS MEDIUM

V. S. Surov UDC 532.529.5

The model of a multivelocity multicomponent medium, which is based on the conservation laws and whose

equations belong to a hyperbolic type, has been presented. A number of problems on disintegration of an arbitrary

discontinuity in a dust-laden gas have been calculated with the Courant–Isaacson–Rees numerical

method.

Keywords: multicomponent multivelocity medium, hyperbolic systems of partial differential equations, numerical

modeling.

NANOSTRUCTURES

HEAT AND MASS TRANSFER IN THE SYSTEM

HYDROCARBON GAS–POROUS CARBON LAYER–METAL

AND FORMATION OF SUPERSATURATED SOLID CARBON

SOLUTIONS

D. A. Takopulo and S. P. Fisenko UDC 536.248

It is shown that the carbon layer formed on the catalytic surface of a metal plays an important role in industrial

technologies of obtaining carbon nanofibers. The effective heat conduction of porous carbon samples

was measured. A mathematical model of the heat and mass transfer inside a carbon layer has been developed

and its stationary solutions were investigated. It is shown that a decrease in the thickness of a porous carbon

layer on the surface of a metal as a result of its cleaning and a further growth of this layer lead to the formation

of a supersaturated solid solution of carbon in the metal.

Keywords: effective heat conduction of a porous layer, diffusion of carbon, time of establishment of a stationary

regime, Pade′ approximation, solubility of carbon in a metal.

PYROLYSIS OF A FEMTOLITER DROP

IN A LOW-TEMPERATURE AEROSOL

REACTOR AT A LOWERED PRESSURE

K. I. Delendik, V. I. Saverchenko,

and S. P. Fisenko

UDC 536.423

The products of low-temperature pyrolysis of a solute in the rapid evaporation of droplets of an aqueous solution

of NiCl2 in an aerosol reactor, were found experimentally. An x-ray spectroscopic analysis has shown

that approximately 37% of nickel atoms pass into oxides. The pyrolysis products possess residual magnetization.

It is also found that the rate of evaporation of nickel and chlorine compounds depends on the radius of

droplets and their mass flow rate.

Keywords: evaporation, nanoparticles, nickel oxide, supersaturated solution, galvanoplastics, x-ray spectroscopic

analysis.

HEAT AND MASS TRANSFER IN COMBUSTION PROCESSES

ON THE POSSIBILITY OF ENHANCING

THE RATE OF COMBUSTION OF GASES

AND GASEOUS MIXTURES

Yu. V. Polezhaev, O. G. Stonik,

and G. V. Gabbasova

UDC 536.461; 536.25

A classification of combustion regimes is given. The influence of various factors on the combustion rate and

height of a flame is shown. Relationships for determining the rates of laminar and turbulent combustion of a

fuel are given.

Keywords: combustion regimes, flame height, scale of turbulent combustion.

METHOD FOR CHARACTERIZING AND CHOOSING

THE SOLID MIXED FUEL FOR MICROTHRUSTERS

OF MICROELECTROMECHANICAL SYSTEMS

S. I. Futko,a V. P. Bondarenko,b

and L. N. Dolgiib

UDC 662.612.2.662.311.1

We propose a method for characterizing and choosing solid mixed fuels for use as the solid-fuel charge of

microthrusters of microelectromechanical systems. The method is based on the solution of the problem on the

dependence of impulse responses of such a microthruster on the diameter of the outlet cross-section of its

combustion chamber and the microkinetic parameters of the fuel. The variants of choosing the above fuels

have been illustrated using glycidyl azide polymer/RDX as the example of a solid fuel mixture. The paper presents

the characteristic criteria determining the composition of mixed fuels for the microthruster of a microelectromechanical

system and considers the main types of "direct" and "inverse" problems arising in

characterizing and choosing such fuels.

Keywords: solid rocket fuel, solid fuel combustion, macrokinetic modeling, solid-fuel rocket engine, microthruster,

thermodynamics, mixed fuel, solid-fuel charge, glycidyl azide polymer, RDX, method, impulse.

MODELING OF THE PROCESS OF BURNING-OUT

OF COKE–ASH PARTICLES IN A FLUIDIZED BED

B. B. Rokhman UDC 532.529:532.517.4

A generalized statistical model of the process of burning out of coal particles in a fluidized-bed furnace is

constructed. It takes into account the kinetics of heterogeneous chemical reactions, as well as radiant and

convective–conductive heat transfer, which made it possible to considerably expand the region of application

of the existing models. Different schemes of the behavior of ash in the process of burning of carbon particles

are considered. Boundary conditions (conditions of matching) were formulated, and analytical solutions for

the distribution function of particles in small intervals of carbon concentration for surface and bulk reaction

have been obtained.

Keywords: distribution function, combustion, particle, gas, polydispersity, temperature, heterogeneous reaction,

concentration, velocity, aerodynamics, fluidized bed.

MICROWAVE TECHNOLOGIES IN COAL POWER ENGINEERING

V. V. Salomatov,a,c S. O. Sladkov,b

and S. E′. Pashchenkoc

UDC 621.311

An analysis of the modern state and prospects of using microwave radiation in the processes of drying, dispersion,

burning, and fine processing of low-rank coals for the purpose of increasing the energy efficiency of

coal technologies and decreasing harmful emissions from them has been carried out. It is shown that the use

of microwave-radiation energy in coal power engineering is a promising method of complex action on coal in

the process of its preparation and burning.

Keywords: microwave radiation, coal, drying, heating, dispersion, cleaning, ignition, burning, processing.

TRANSFER PROCESSES IN A LOW-TEMPERATURE PLASMA

INFLUENCE OF CLUSTERING ON THE EFFECTIVE

ADIABATIC EXPONENT OF A LOW-TEMPERATURE

CARBON PLASMA

N. I. Alekseev,a,b B. I. Reznikov,a B. G. Zhukov,a

S. V. Bobashev,a S. A. Ponyaev,a and R. O. Kurakina

UDC 532.525, 537.523

Calculation of the equilibrium composition and the effective adiabatic exponent of a low-temperature carbon

plasma containing neutral and charged carbon clusters up to the clusters C15 has been carried out. The

range of temperatures and pressures at which carbon atoms associate into multiatomic clusters has been determined.

It has been shown that the effective adiabatic exponent of carbon plasma is a composite nonmonotonic

function of temperature, which has a substantial effect on the flow of a carbon-plasma jet out of

channels and on plasma-flux flow past various obstacles.

Keywords: railtron, rail accelerator, plasma jet, carbon clusters.

NUMERICAL MODELING OF ARC PLASMA

GENERATOR FOR CHEMICAL LASER APPLICATIONS

Vidya Sagar,a Chhaya Ravikant,b

Gaurav Singhal,a and Alok P. Mittalc

UDC 535.2/.3+621.375

The results of the numerical modeling of arc discharge phenomenon relevant to hydrogen fluoride/deuterium

fluoride (HF/DF) laser applications are given. The overall mechanics of arc discharge phenomena on the

basis of numerical modeling employing the commercial code COMSOL is discussed. The equations for a 2D

axisymmetric, weakly compressible, laminar flow with heat transfer and the coupled hydrodynamic and electromagnetic

equations are solved using the SIMPLE algorithm. The variations in the material properties, temperature,

and velocity due to the generated arc are studied. A comparison of the results obtained with those

from the studies available in the literature validates the computational data. Since each designed plasma arc

tunnel is unique in itself and specific in application, this would enable one to alter arc discharge parameters

to optimize a specific laser.

Keywords: HF/DF, arc plasma generator, COMSOL.

HYDROGASDYNAMICS IN TECHNOLOGICAL PROCESSES

MODELING OF REFLECTION OF DETONATION

AND SHOCK WAVES FROM A RIGID WALL

IN MIXTURES OF A REACTIVE GAS

AND CHEMICALLY INERT PARTICLES

A. V. Fedorov,a P. A. Fomin,b

D. A. Tropin,a and J.-R. Chenc

UDC 534.222

An algorithm of approximate calculation of the reflection of detonation waves in mixtures of a reactive gas

and chemically inert microparticles has been proposed. Consideration has been given to the case where the

gas behind the wave front is in chemical equilibrium (D → D reflection). It has been shown that the presence

of the condensed phase can substantially decrease the parameters of the reflected wave (its velocity, pressure,

and temperature). Within the framework of a one-dimensional nonstationary approach and with allowance for

the detailed kinetics of chemical reactions, the evolution of the shock wave in a stoichiometric hydrogen-oxygen

mixture with sand particles in its reflection from a rigid wall has been calculated. The limiting particle

concentration below which the reflected wave is of the detonation type and above which it is of the shock

type has been found.

Keywords: suppression of gaseous detonation, gas-particles mixture, explosion safety.

NUMERICAL SIMULATION OF THE SELF-ORGANIZATION

OF CONVECTIVE STRUCTURES IN A THIN LAYER OF LIQUID

I. N. Shishkova, V. Yu. Levashov,

and A. P. Kryukov

UDC 532.527

Complex convective structures observed experimentally in a thin layer of liquid are investigated numerically.

To study this kind of phenomena, a mathematical model is suggested based on the interaction of two such opposite

factors as the randomness of convective motions in the medium of interest as a whole and intensification

of these motions by local sources that introduce correlations into a random process. The results obtained

by mathematical simulation qualitatively reflect the most characteristic phenomena noted in the experiments.

Keywords: convective structures, numerical simulation, thin liquid layer.

CONDUCTION–CONVECTION–RADIATION EFFECTS

ON THE FLOW OF OPTICALLY DENSE GRAY FLUID

OVER A HORIZONTAL CIRCULAR DISK

S. Siddiqaa and M. A. Hossainb UDC 536.25

A natural convection boundary-layer flow of an optically dense gray viscous fluid (liquid metal) above a horizontal

circular disk with regard to thermal radiation is discussed. The radiative heat flux term is expressed

by using the optically thick radiation limit. The corresponding boundary-layer equations are solved with the

aid of three distinct numerical techniques: the straightforward finite difference (SFD) method is employed to

solve the problem directly, and then the stream function formulation (SFF) and primitive variable formulation

(PVF) methods based on solving transformed equations are used. The numerical results are interpreted in

terms of the local skin friction coefficient and the local Nusselt number. The influence of the problem parameters

on these characteristics is shown.

Keywords: natural convection, thermal radiation, horizontal circular disk.

LOCAL THEORY OF PARALLEL APPROACH

OF PLATES IN AN INCOMPRESSIBLE LIQUID

S. K. Betyaev UDC 532.526.2

A flow of an incompressible liquid in a thin layer between two approaching disks or plates located in parallel,

at the final stage of their symmetrical approach, is considered. It is assumed that the velocity of the body

is assigned as a function of time. An inspection analysis of the problem has been made: the types of flows

depending on the law of approaching plates and the conditions under which the pressure in the layer and,

consequently, the acting forces increase infinitely have been determined. Approximate solutions in the plane

and axisymmetric cases are suggested. Exact solutions have been obtained for infinitely small and infinitely

high Reynolds numbers.

Keywords: incompressible liquid, law of approaching plates, viscous flow regime, highly viscous flow regime,

inviscid flow regime.

STERNBERG–KOITER PARADOX IN

PROBLEMS ON INVISCID FLOW OF FLUID

S. K. Betyaev UDC 532.526.5

The problem on inviscid flow of fluid inside a wedge when the Sternberg–Koiter paradox takes place has

been considered. The flow is divided into potential and vortex and stationary and nonstationary ones. A resolution

of the paradox is given.

Keywords: singularity, bifurcation, self-similarity, superposition.

SOME TWO-DIMENSIONAL FLOWS WITH COUPLE STRESSES

M. Sajid,a N. Ali,b Z. Abbas,b

T. Javed,b and M. Imranc

UDC 532.5

The effect of couple stresses on some two-dimensional flows is considered. The numerical solutions are obtained

by the shooting method using the Runge–Kutta algorithm in the four flow problems for a couple stress

fluid, namely, for the Blasius, Sakiadis, stretching, and stagnation-point flows. The obtained solutions are nonsimilar

for the Blasius and Sakiadis flows. The results are interpreted concerning the influence of the couple

stress parameter which is a measure of the polarity of a fluid. It is shown that for large values of this parameter

the solution converges to the solution for a Newtonian fluid.

Keywords: two-dimensional flow, couple stresses, Blasius flow, Sakiadis flow, stretching flow, stagnation-point

flow, numerical solution.

TRANSFER PROCESSES IN RHEOLOGICAL MEDIA

RHEOLOGY DYNAMICS OF THE BLOOD AND PLASMA

OF RATS AFTER TRANSDERMAL LASER IRRADIATION

OF THE TAIL VEIN IN THE INFRARED RANGE

I. V. Yamaikina,a V. A. Mansurov,b N. B. Gorbunova,c

L. E. Batai,d V. S. Ulashchik,c and V. A. Orlovichd

UDC 577.344.3

Single transdermal laser irradiation of the tail vein of males of white mongrel rats with an average mass of

350–400 g in three different regimes has been carried out. The irradiation doses were chosen to be intermediate

between therapeutic and surgical ones, and the radiation wavelengths were 806 nm and 2 μm. The dynamics

of the packed cell volume, deformability and cytometric indices of erythrocytes, and of the plasma and

blood viscosity have been investigated. The rheological and cytometric changes in the blood caused by the irradiation

stayed for several days. The observed rheologial changes are due to the removal of irradiation-damaged

erythrocytes and the arrival in the blood channel of young and highly deformable red cells.

Keywords: viscosity, blood, plasma, deformability of erythrocytes, infrared spectral range, laser irradiation.

RHEOLOGICAL PROPERTIES OF DISPERSE SYSTEMS

BASED ON HYDROLYZED LIGNIN AND OIL

T. A. Savitskaya,a I. V. Reznikov,a V. A. Shcheglov,a

N. G. Tsygankova,b G. M. Telysheva,c and D. D. Grinshpanb

UDC [66.081.3+665.7]:634.0.864

The rheological properties of oil dispersions of hydrophobized hydrolyzed lignin, which is an effective sorbent

of oil and oil products, have been studied. It has been shown that at a lignin concentration of over 10%,

free-disperse systems with Newton flow go over to coagulation thixotropic structures, demonstrating the

pseudoplastic character of flow. The structural-mechanical characteristics of highly filled (lignin content of

40–45%) dispersions have been determined and the concentration region of existence of an oil-saturated sorbent

in the form of a solid product easily removed from the water surface has been established.

Keywords: rheological properties, oil, lignin, dispersion.

MATHEMATICAL MODELING OF THE FORMATION

OF CLOTS IN BLOOD VESSELS

E ′

. M. Khramchenkov and M. G. Khramchenkov UDC 532.546

A mathematical model of the formation of a clot (thrombosis) has been constructed in which the fibrin of the

clot is considered as an elastically deformable solid phase of variable mass and the prothrombin, thrombin,

fibrinogen, and fibrin monomers as components of the liquid phase. As a result of numerical solution of the

model, data on the influence of various parameters of the process of thrombosis on the rate of clot formation

have been obtained.

Keywords: blood vessels, clot, thrombosis, vessel wall, thrombin, prothrombin, fibrinogen, fibrin network.

HEAT CONDUCTION AND HEAT EXCHANGE IN TECHNOLOGICAL PROCESSES

ON THE INFLUENCE OF ASYMMETRY ON THE VELOCITY

OF MOTION OF ISOTHERMS NEAR THE THERMAL CENTER

OF A COOLED BODY

V. V. Vinogradov,a I. L. Tyazhel’nikova,a

and E. P. Vinogradovab

UDC 536.2

A study has been made of the influence of asymmetric cooling of bodies due to the temperature difference on

the surfaces, the difference in thermophysical characteristics of the media, and the geometry of the body on

the velocity of motion of isotherms as they approach the thermal center. The results have been used for elucidation

of the causes of certain thermophysical features appearing when continuously cast ingots solidify in

horizontal continuous casting plants and when the bloom molds are replaced by slab molds in continuous

ingot casting machines. An analytical expression for the displacement of the thermal center of a plate in formation

of media with different thermal-diffusivity coefficients has been obtained.

Keywords: cooling of an ingot, velocity of motion of isotherms, thermal center, asymmetry, heat-conduction

equation, solidification of a continuously cast ingot, thermal diffusivity.

ANISOTROPY OF THERMAL CONDUCTIVITY

OF FERRO-FILLED POLYVINYLCHLORIDE

B. B. Kolupaev UDC 541.64:532.72

The contribution of the constant external magnetic field to the anisotropy of thermal conductivity of polyvinylchloride

(PVC) containing powders of highly dispersed ferromagnetics (iron and magnetite) as a filler has

been determined. The relationship between the thermal conductivity coefficient of such PVCs, the direction of

the heat-flux vector, and the normal to the isotherm of the composite has been established. It has been shown

that for the systems "PVC + 2.0 vol. % Fe" and "PVC + 2.0 vol. % Fe3O4" formed on exposure to an external

magnetic field, the value of the principal axes of the thermal-conductivity coefficient depends on the

type of filler. A comparison of the calculated and experimental values of the sought quantities has been made.

Keywords: anisotropy, magnetite, heat conduction, heat flux.

TOWARDS THE DYNAMICS OF THE TEMPERATURE FIELD

GRADIENT IN A LAYER OF AN INORGANIC MATERIAL

UNDER RADIATION HEATING ACCORDING TO THE DATA

OF EXPERIMENTS AND NUMERICAL MODELING

V. R. Sobol,a P. N. Goman,b

and O. N. Mazurenkoc

UDC 536.331

We have investigated the process of temperature field formation in a layer of a weakly conducting medium

with the example of wood and green moss under irradiation of one side with an energy flux and contact heat

removal through the opposite back surface of the material onto an asbestos-cement support. The experimental

results were compared with the data calculated on the basis of the relations of nonstationary heat transfer in

the approximations of closeness and openness of the system. The conditions for heat removal suppression have

been concretized and the role of the energy exchange under the prolonged action of radiant energy for estimating

the thermal stability parameters of related materials has been elucidated. The obtained data can be

used to control radiant fluxes in treating wood, for effective heating of living and industrial premises, improving

the methods for opposing high energy fluxes, and preventing the propagation of fire in inhabited localities

and in park and forest zones.

Keywords: temperature, temperature gradient, heat flow, heat conductivity, heat capacity, heating, heat removal,

green moss, flammability.

MISCELLANEOUS

THERMAL AND NEUTRON-PHYSICAL FEATURES

OF THE NUCLEAR REACTOR FOR A POWER

PULSATION PLANT FOR SPACE APPLICATIONS

E ′

. G. Gordeev,a A. S. Kaminskii,a G. V. Konyukhov,b

V. A. Pavshuk,b and T. A. Turbinaa

UDC 621.039.5

We have explored the possibility of creating small-size reactors with a high power output with the provision

of thermal stability and nuclear safety under standard operating conditions and in emergency situations. The

neutron-physical features of such a reactor have been considered and variants of its designs preserving the

main principles and approaches of nuclear rocket engine technology are presented.

Keywords: nuclear power plant, nuclear rocket engine, modular design, energy production, thermal stability,

nuclear safety, reactivity effects, burnable neutron poison, fission density.

INVESTIGATION OF THE PHOTOELECTRIC

CHARACTERISTICS OF PHOTODIODE STRUCTURES

WITH SILICON-BASED POTENTIAL BARRIERS

O. A. Abdulkhaev, G. O. Asanova,

D. M. Yodgorova, and A. V. Karimov

UDC 621.383.52:535.243

Based on silicon with a base region thickness of 300 μm, phototransforming Au–nSi–Au structures with potential

barriers are prepared. The diode structures obtained possess high photosensitivity in the spectral region

0.9–1.1 μm at low illumination intensities of 10 lux (up to 5 A/W). Based on investigations of the

photoelectric characteristics, it has been established that the Au–nSi–Au structures in the range of temperatures

from room temperature to 40oC at low working voltages (0.1–0.2 V) are distinguished by the weak temperature

dependence of photocurrents. In principle, in the spectral range 0.7–1.1 μm the Au–nSi–Au

structures obtained can easily replace both gallium arsenide and classical silicon photodiodes with one rectifying

junction in optoelectronic devices.

Keywords: photoelectric characteristics, photocurrent, potential barriers, base region, silicon, photodiode structure.

REFLECTIONLESS TRANSMISSION OF ELECTROMAGNETIC

RADIATION THROUGH A MAGNETIC–DIELECTRIC SYSTEM

G. A. Mamedov, E′. G. Ismibeili,

and S. R. Kasimova

UDC 621.365

The conditions and frequency band of reflectionless transmission of electromagnetic radiation through a plane

absorbing layer of a magnet that separates two semi-infinite nonabsorbing dielectric media have been found.

The dependence of these conditions on the separating layer thickness, magnetic and dielectric properties of

the layer substance, and of the adjacent substrate is investigated.

Keywords: absorption of electromagnetic wave, magnetic coating, dielectric substrate.