![[About Institute]](../../graphics/aboutins.gif)
Investigations of the unsteady free-convection heat transfer and the flow structure in a horizontal cylindrical annular gap have revealed that the hydrodynamic structure exerts an essential influence on temperature distribution in the gap and the most important factors, which determine the Nusselt number variation in the presence of eccentricity is mutual position of free-convective vortices in the stagnant zone of the flow as well as a ratio of their scales. An optimal method for forming pulsed-periodic jets and ring-shaped vortices which makes it possible to increase an accuracy of calculations of high-power cooled engines has been proposed.
A physical-mathematical model of dispersing the liquid-liquid system in a shear turbulent flow is developed. Numerical calculations are made of the probability density distribution function of liquid particle diameters in a strong shear turbulent flow. An influence of the mean length scale and turbulence energy on homogenization of the liquid-liquid system is investigated. As a result of the research conducted a disperser-homogenizer has been designed for food industry and, in sight, for power engineering which allows a degree of homogenization and dispersing of the system to be increased and energy consumptions to be reduced.
By numerical modeling of gas mixture combustion in a porous medium consisting of large elements the existence of pulsating and oscillatory modes of combustion is forecast which is of importance for creating the promising working bodies of burners.
Original experimental setups are devised in which the silane-to-disilane conversion in nonequilibrium plasma is accomplished with the desired product yield of up to 85%. A process of oxidation of organic impurities in air in a hyperadiabatic combustion wave with a purification degree reaching practically 100% is realized.
A highly descriptive method and devices of computational infrared thermography are developed for non-destructive testing of the quality of heat insulation of industrial objects and constructions implemented in thermographic investigations of liquid ammonia reservoirs and technological pipelines at the Grodna Production Association "Azot".
A new mathematical model and simulation method for X-ray photons scattering process are developed. It allows the simulation time decreasing more than ten times in comparison with the Monte-Carlo method. The results obtained are applied for the backscattering tomography performance optimization.
The mechanisms of magnetic field action on appearance and formation of acoustic cavitation in magnetic fluids are discovered. It is shown that the growth of erosion activity is caused by separation effect of ponderomotive compressing of the colloid solutions when the magnetic intensity gradient in cavitation zone is increasing.
A model for study of magnetization processes of polycrystalline ferromagnets with taking into account the interdomain magnetostatic interaction is developed. The reasons of nonlinear dependence of magnetization reversible component on an external magnetic field intensity are investigated. The occurrence of nonsymmetric minor loops, formed at a magnetization of ferromagnet by a weak low-frequency and direct current magnetic fields, is explained.
Theoretical models of both diffusive-condensation mechanism and wall film flow mechanism for mass transfer in conical capillary immersed in liquid are worked out. It is established that the second model gives good agreement with experimental results. It testifies to decisive role of film flow mechanism in physical nature of the phenomenon of double-side filling with liquids of one-side-closed conical capillaries.
New theoretical backgrounds, algorithms and technique for limited projections and views X-ray 3-D-tomography are developed, which are based upon the solution of imposed operational equations using a priori knowledge. It allows to reduce strongly (by 10--100 times) the number of necessary projections and expand the range of the objects for tomographic inspection.
The diamond containing coatings have been developed which allows to optimize modes of operation of the abrasive tool and parts of friction units. The processes of creation superficial composite diamond containing layers and ceramic films on parts from different constructional materials have been investigated. The regimes of formation of diamond containing coatings on grinding and diamond cutting wheels have been developed.
For disperse-hardening alloys a mathematical model of a crystal with spherical microcavities chaotically placed in it or inclusions with isomorphic in relation to a matrix phase by a lattice have been developed. The computer programs for calculation of a diffraction of X-ray beams on an ensemble of such particles in view of them interfering interaction have been worked out.
The mathematical models of an emergency condition for elements of complex technical systems have been founded and selected. The theoretical backgrounds of construction of mathematical model of an emergency condition for complex systems as a whole have been developed. The methodical approaches for creation of models of an emergency condition of technical complexes of the Republic of Belarus in view of their influence to an environment have been worked out.
The structures of composite materials on the basis of aluminum with nonmetallic components (oxides, carbides, etc.) and regimes of formation on them of ceramic coatings by method of electrochemical microplasma oxidation have been developed. The pilot samples of friction pairs for face seals from composite materials on the basis of aluminum with the oxide-ceramic coating have been fabricated for main petroleum pumps.
The diagnostic models of an evaluation of the qualitative characteristics of drive mechanisms on the basis of their diagnostics without any disassembly have been developed, the fundamental schemes of diagnostic complexes have been created. The microprocessor systems and hardware-software means for studies of tooth and cog meshing and accelerated estimation of the service characteristics of lubricant materials allowing to reduce essentially terms of creation of new engineering products significantly have been created.
From the positions of evaluating the complex influence of heat, dynamic and metallurgical parameters on the process of shaping a transition area when getting the bimetallic casting, cardinal principles are formulated and novel methods are offered of getting the bimetallic stocking up, in which components are connected in a liquid phase condition not mixing in the process unceasing lithoes.
A series of heat exchange apparatuses ensuring a deep heat recovery of ash-laden and toxic removal gases of industrial plants and furnaces with simultaneous purification from fine-dispersed ash and soluble substances with the term of self-compensation of 1.5 years has been developed.
The analysis of the ways of the development of Belarus system of electro-generating sources with due account of the schedule of the units of plants being put into operation and being decommissioning has been carried out. With the help of WASP III+ software, having been developed in the Aragonne National Laboratories (USA) with the IAEA assistance, it has been shown that still to 2005 the deficit of the installed capacity will constitute about 2,000 MW in the Republic of Belarus, and up to 2010 - about 6,000 MW. One can expect a sufficient decreasing of the cost of energy generation when 4 units of NPP being put into operation.
An express method for determination of nitrozometylamine and nitrites with the help of analytical spectrometric complex "Kanas-1" has been first developed and tested on the samples of soils, water and air. It allows to control the level of the contamination of the environment in the places of nuclear power plants' location which effect on the increasing of the level of the contamination of the given locality with carcinogenic substance.
Samples of different types of soils have been analyzed as to the content of transuranium elements. The correlation of radionuclides has been studied and an instrumental method for the control of plutonium content according to the measured g-activity of 241Am has been suggested on its basis. The g-spectra of soil irradiation from the zone of the Chernobyl accident, Semipalatinsk Proving Ground (Kazakhstan), the region of Chemical Group of Enterprises "Mayak" (Russia) have been studied. (In co-operation with the Moscow Engineering-Physical Institute, Russia and the National Nuclear Center, Kazakhstan.)
The calculations supporting the project of experimental investigations on transmutation of long-lived nuclear power plant waste (fission products and minor actinides) in a subcritical assembly driven by a neutron generator have been carried out. It has been shown that such approach gives an opportunity to investigate most important regularity of long-lived radionuclides transmutation avoiding expenditure for very expensive proton or nuclei accelerator. In such subcritical assembly it is possible to simulate different neutron spectra that may be characteristic for Accelerator Driven Systems. The neutron generator NG-12-1, one of the most intense in Europe, has been put into operation. Recent efforts were devoted to putting into operation a graphite column (thermal assembly) for carrying out the neutron activation analysis.
The effect of irradiation on radiative-chemical decomposition of vapor in the presence of silicon-aluminas with ratio of SiO2/Al2O3=42.3, silicon-boron glasses, industrial catalysts (alumino-platinum AÏ-56 and palladium ÏÊ-3Ø), copper-magnesium and high porous ceramics on base of Al2O3, SiO2, ZrO2, MgO under the temperatures 400, 450, and 500 oC and dose rates up to 2 Gy/s has been investigated. It was shown that temperature increase did not effect the yield of molecular hydrogen; it depends on dose rate only.
A mathematical model of gaseous coolant motion through a heat releasing fuel assembly with micro-spherical fuel elements inside an annular gap between inner porous plug and outer drums with the coolant supply into inner hole and fuel layer has been developed. On the basis of the mathematical model a technique and computer code for thermodynamic calculation of the fuel assembly have been worked out.
Exactly solvable models for quantum theory of scattering for multidimensional and three-body problems in the regular and singular cases have been worked out. The examples are given of exactly solvable models taking into account the procedure of Bargman's potentials application to parametric family of inverse problems and systems of equations with covariant derivative. The problem of level crossing has been investigated proceeding from exactly solvable models of parametric inverse problem and analysis of two-channel exactly solvable models. It was shown that quantum systems with Bargman's regular potentials take a geometric phase by level crossing even in one-dimensional case of slow motion but they are not revealed by even number of crossings.
The investigations of A-mass range applicability of the optical model built using soft nonaxial rotator nuclear Hamiltonian has been carried out by couple channel method. An analysis of the experimental data on neutron scattering by 12C nucleus has shown that this method may be used for the deformed nuclei in the range of A~10. The computer code has been developed using neutron penetration values of the model for analysis of processes running along with compound nucleus creation.
The principles of classification of regional ecological-social-economic systems (RES) by the level of chemical and radiation contamination, the properties of functioning and development of RES have been considered. The concept of interference as the way of support of stability and development of RES has been formulated. The organization of the subsystems of planning and management of radiation-ecological safety at the governmental, sectoral and regional levels. The hierarchical structure of RES problems in remediation of contaminated territories is suggested. The criteria of evaluation of the actual state of the environment objects, human health and dependence on the value of detriment have been formulated. The results obtained make it possible to work out the more well-founded plans for remediation, taking into account the expenditures on carrying out the countermeasures.
The forms of existence of 137Cs and 90Sr radionuclides in the radioactive wastes generated after decontamination in disposal sites located in the nearest (the Pripyat trace) and in the distant (the Sozh trace) zones of deposition of radionuclides in the Gomel Region were studied. It has been found out that in the radioactive wastes of the nearest zone these values are equal to 0.1--0.2%, 5.6--9.8% and 90--94.3%, respectively. In the wastes of the nearest zone there are 0.6--33% of radiostrontium in water-soluble form, in exchangeable -- 8.2--31.6%, and in non-exchangeable -- 65.1--91.2%. In the distant zone these values are equal to 5--8%, 45--57% and 35--50%, respectively.
The calculation model for determination of gas-pollution of the territories near high-ways by the exhaust gases of the motor transport has been developed. The model takes into account the effect of town planning, climatic, high-way characteristics and characteristics of traffic flows. It makes it possible to calculate the discharge of harmful substances in the surface air layer of the urban highways, the concentration of harmful substances in the surface air layer of the urban highways, the limited permissible concentrations from the traffic flow for each urban high-way or its part.
The methods of the agrochemical effect on the increase of mobility of radiocaesium in various types of the soil have been studied. It has been shown that the treatment of the soil by potassium nitrates, ammonium and caesium changes the mobility of 137Cs increasing its biological accessibility approximately by 2 times. The increased ability to desorption by the above extragents is seen for sod-sand and sod-podzol soils. The investigations have been also carried out on fixing the mobile forms of radiostrontium by introduction of various additives into the soil, such as sulphate (gypsum water, sodium sulphate) and phosphate (ammophos, one-substituted sodium phosphate, sodium polyphosphate) compounds. The greatest effect of fixation of mobile forms of radiostrontium is seen after introduction of phosphate additives (20--80%) and depends on the type of the soil and granulometric composition.
The physical-chemical foundations of the processes of synthesis and sintering ceramic materials in high-frequency fields are worked out. The technology of high-frequency fire of wares from ceramics are elaborated. The ceramic materials on the base of ferrites and refractory oxides for wares of electronics and ceramic tools are proposed.
Some alloying elements such as Mg, Ba, Se, Ti, Mn, Cr and others are determined. They allow to decrease film/silicium substrate interaction and transition resistance values between levels, to modify film structures and increase electromigration and thermal stability. The developed systems of three- and four-component alloys correspond to the requirements of a given level of current-carrying systems. The ranges of varying the alloying element concentrations in these alloy systems are determined.
The deposition of Al2O3-base ceramic coatings on aluminum alloys has been investigated by the method of microarc oxidation. It is established that color characteristics of coatings can be controlled with the aid of a proper selection of electrolyte compositions and oxidation conditions and a wide color scale can be obtained from milk-white to black colors. A subsequent e.b. surface heating is shown to result in densifying a ceramic layer and improvement of its structure.
The composite aluminum-graphite alloys were investigated regarding to an interaction between aluminum and graphite that is added into a melt in the form of fine particles. It is established that AlC4 and AlC carbides are formed. When alloying the alloy with carbide-forming elements such as Si and Fe, a carbide formation is increased and with the elements which do not form carbides it is decreased. These elements are Cu, Zn and Ni. The addition of surface-active elements such as Sn, Pb and Cd suppresses the carbide formation. Therefore, it is possible to make a specific control of a structure of aluminum-graphite alloys and consequently their service characteristics.
The relationship is determined between morphology, structure, phase state of powder-like magnetic-hard material particles of Fe-Nd-B system and hysteresis properties of permanent magnets produced using the method of plastic compacting in vacuum. Phase components and their morphology are shown to affect a mechanism of steel magnetization reversal. A high-coercitivity state is achieved due to retarding the domain walls and a magnetization results from a rotation of magnetization vectors of separate domains.
The investigation is made of a titanium effect on physical-chemical processes which occur in the zone where grains of AC-6 synthetic diamond contact with iron and iron-carbon alloys. Strength properties of diamond-containing copper-tin base composites are also investigated. It is established that adhesion of titanium takes place on diamond grains and it chemically interacts with a free carbon under the conditions of microcutting with high pressure and temperature when a speed of relative motion is equal to 15 to 20 m/s. This leads to formation of protective films 5 to 10 (m thick which results in decrease of wear and failure of grains and bond by a factor of 1.5 to 1.8. The hardness of a diamond-containing composite is 14 to 20 kgf/mm2.
On the basis of experimental and theoretical investigations in the field of physics and mechanics of solid friction a theoretical analysis has been accomplished of the actual contact spot (ACS) dependence on temperature at friction. It is established that the ACS passes its minimum under the growing contact temperature and a certain correlation of thermophysical and mechanical properties of contacting materials. The minimum is conditioned by the competing influence of the material heat expansion and impairment of its mechanical characteristics at frictional heating.
The kinetics of temperature field variation on a single contact spot and neighboring areas has been theoretically studied. The cyclicity has been established of heat loading concentration on the actual contact spots. An experimentally verified concept is suggested of thermomechanical wearing of a tribosystem with a thermoelastically unstable contact. The results obtained are of a major practical importance for heat dynamics, design and calculation of friction joints in machines and mechanisms, etc.
Wear of highly filled frictional polymer composites was found to follow adhesion mechanism. This is mainly because of weak boundary layers formed due to adsorption on fiber and dispersed filler surface in the plasticizer liquid phase. A model has been elaborated to calculate temperature fields on the friction contact surface for the case of axially directed linear frictional heat flow. The model accounts for structural changes in contacting materials as applied to inertia tests of braking systems.
The chemical composition of epoxyphenolic adhesive polycondensation products both in the bulk and thin layer bordering on metal surface has been studied. It is shown that the composition of the volume polycondensation products differs much from that of products liberated during oligomer solidification in the thin boundary layer. Variation of chemical composition is governed by thermosorption processes on the metal surface. Most prominent action on the polymer boundary layer structure and properties is exerted by desorbed from metal surface carbon oxides participating in carbonylation and carboxylation. Based on the results obtained new composites have been developed and adopted at the Production Association "Belaruskalii" to produce abrasive tools and wear-resistant coatings on suction dredge parts and pipelines for chemically reactive solutions containing abrasive particles.
A method has been elaborated to investigate thermal stability of polymers and composites on their base in conditions of intense IR-heating. Thermostability of a series of thermoplastic polymers has been estimated under different intensity IR- and UV-irradiation. In particular, polyethylene terephthalate shows a considerable (up to 2 times) increase in crystallinity under IR-radiation and negligible under UV-radiation, while prolonged heating at 150 oC does not change noticeably its structural state. Transformations induced by thermodestruction were not observed in both cases. Increase in IR-heating intensity leads to simultaneously running processes of macromolecular cross-linking and their destruction; UV-action initiates thermooxidative processes. The established regularities are the base for creation of new efficient composite materials in gas-thermal processes.
Adsorption of polyethylene macromolecular melt has been studied on metal oxides surface using paramagnetic probing. It has been found out that with increasing mineral filler content in the polymer matrix a transition of the stable iminoxylic radical is observed in the region of critical concentrations from the area of fast transformations to the slow one. The concentration critical values are dependent on the components phase interaction. They drop with increasing specific area and reducing particle size of mineral fillers. The data obtained serve the basis for the method of selecting mineral filler by its sorption activity, granulometric state and specific surface area when developing polymer composites.
![[About Center]](../../graphics/aboutcen.gif)
The investigations of structure and element-chemical composition of diamond-like carbon films (DLC films), prepared by the method of pulsed electroerrosive deposition in vacuum, have been carried out. By methods of IR spectroscopy, ESCA, electron microscopy and electronography it have been shown that DLC films are the three-dimensional system consisting of transition layer on the substrate-film boundary, containing carbides of the substrate material, surface layer in width up to 5 nm, having admixtures up to 3% of adsorbed oxygen and other gases in its composition. Element composition of the third main film layer practically coincides with the composition of atomized cathode.
From the experimental data analysis and the structure simulation of near structure order it have been shown that DLC film is cluster material with impregnation of polycrystal dimensions and separate monocrystals of graphite and carbon (less than 1--3%). Clusters are ordered fragments of londsaylit and turbostructure graphite like carbon of a 0.5--3 nm size. Characteristic ESCA spectra and electronogram maxima testify to presence of chain fragments of sp1 hybridizated carbon atoms in films. The hybridizated sp3-bonds of carbon atoms, character for diamond, are the main type of chemical bond in DLC film. The estimation of the quantity content of this bonds is up to 70%.
The investigations of the electrotransfer properties dependence on the texturation degree of YBaCuO films prepared by the pulsed laser condensation method are carried out. It is established that as against polycrystal films with arbitrary grains orientation, having the resistance dependence on temperature R(T) character for metals, texture films in which the current direction coincides with the axis direction c (the texture axis) have the characteristic semiconductor type R(T) from 200 K to the transition temperature in semiconductor state. From the measurements of the electrical film characteristics it is established that the temperature dependence distinctions of the films resistance with the different texture degree are caused by the distinctions of the current-transfer mechanisms along axes (a, b and c).
It was created the experimental deposition technology of abrasive coatings on the diamond-like carbon films base. The polymeric tape material in width 400 mm was used as the wearer. The experimental patterns for the precise superfinish details treatment of total square 20 m2 were manufactured. Using the preliminary results of the tests carried out in the firm 3M (USA) the optimization of the technological manufacture regime of the present abrasive was made.
Complex methodology of synthesis of optimum mass-geometrical parameters of high-effective transport mobile machines is developed on the basis of mathematical modeling of operational regimes and of multicriterial optimization.
New search method for simulation of vehicle real vibration loads based on identification is developed increasing the convergence of control algorithms in 1.7 times comparing to known methods.
A set of algorithms and programs for calculation of speed parameters, fuel consumption and loading of elements of transmission of the heavy mobile machine on the basis of computer modeling of its movement in characteristic road conditions with the purpose of optimization of process of power unit control is developed.
On the basis of theoretical analysis of large experimental data volume the possibility for using the diagram of cycle crack-resistance -- dependence of fatigue crack development from intensity strength coefficient for metal fatigue diagnostics is found.
The concept of automated system for testing of automotive power unit's microprocessor control system (ÌÑS) in on board and in laboratory conditions and algorithms of program modules for system of realization of tests ÌÑS of the diesel engine and transmission of the automobile are developed.
![[About Division]](../../graphics/aboutdiv.gif)
The construction of electrochemical cell for scanning tunneling microscope has been developed. In the air for cleavage of pylolitic graphite the atomic resolution has been obtained. Using Scanning Atomic Force Microscopy and Surface Enchanced Raman Scattering the structures of thiamin and flavine adenine dinucleotide adsorbed on a silver electrode were investigated. It has been proved that both short- and long-range enhancement mechanisms are significant. (In cooperation with the Ya.Kupala Grodna State University.)
The main values and action trajectories of expansion stresses occurred under influence friction forces in high-filled composites under high temperature extrusion were obtained analytically and experimentally. The dimensions of expansion area for typical forms of extrusion channels were found. The influence of rheological condition of deformed composite in sluggish state on conditions of surface defects (the cracks) occurrence. The calculation method for extrusion mechanisms accounting peculiarities of particle-to-particle friction in high filled composites under its processing was developed.
Source: "Main Results of Fundamental Research. 1996--1997". Eds. F.A.Lakhvich and N.N.Kostyukovich. National Academy of Sciences of Belarus, Minsk, 1998.
 Academy |
| The NASB Presidium Information Server Links: | ||||
| About Academy • Organizations • Academy Activities • Other Sites • Full Index | ||||
|
History • Officers • Membership • Staff • International Relations • Academy's Prizes Departments • Institutes • R&D Activities • Research Programs • Conferences Legislation • Publications • Library • Museums • Archive • Publishing House |
![[NASB Home]](../../graphics/homebutton.gif){kind=small} Home |
![[Scientific Sites]](../../graphics/sciencebutton.gif){kind=small} Science |
![[Belarus Sites]](../../graphics/countrybutton.gif){kind=small} Country |
![[World Sites]](../../graphics/worldbutton.gif){kind=small} World |
[ Home | Science | Country | World ]